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Article

Crystal Structures of Xenon(VI) Salts: XeF5Ni(AsF6)3, XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), and XeF5A2F11 (A = Nb, Ta)

by
Zoran Mazej
* and
Evgeny Goreshnik
Department of Inorganic Chemistry and Technology, Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana, Slovenia
*
Author to whom correspondence should be addressed.
Molecules 2023, 28(8), 3370; https://doi.org/10.3390/molecules28083370
Submission received: 20 March 2023 / Revised: 7 April 2023 / Accepted: 9 April 2023 / Published: 11 April 2023
(This article belongs to the Special Issue Synthesis, Characterization and Crystal Structure of Coordination Compounds II)
Browse Figures
Versions Notes

Abstract

:
Experiments on the preparation of the new mixed cations XeF5M(AF6)3 (M = Cu, Ni; A = Cr, Nb, Ta, Ru, Rh, Re, Os, Ir, Pt, Au, As), XeF5M(SbF6)3 (M = Sn, Pb), and XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn) salts were successful only in the preparation of XeF5Ni(AsF6)3. In other cases, mixtures of different products, mostly XeF5AF6 and XeF5A2F11 salts, were obtained. The crystal structures of XeF5Ni(AsF6)3, XeF5TaF6, XeF5RhF6, XeF5IrF6, XeF5Nb2F11, XeF5Ta2F11, and [Ni(XeF2)2](IrF6)2 were determined for the first time on single crystals at 150 K by X-ray diffraction. The crystal structures of XeF5NbF6, XeF5PtF6, XeF5RuF6, XeF5AuF6, and (Xe2F11)2(NiF6) were redetermined by the same method at 150 K. The crystal structure of XeF5RhF6 represents a new structural type in the family of XeF5AF6 salts, which crystallize in four different structural types. The XeF5A2F11 salts (M = Nb, Ta) are not isotypic and both represent a new structure type. They consist of [XeF5]+ cations and dimeric [A2F11]− anions. The crystal structure of [Ni(XeF2)2](IrF6)2 is a first example of a coordination compound in which XeF2 is coordinated to the Ni2+ cation.

1. Introduction

The synthesis of XeF6 was first described in 1962 [1]. It was prepared by the reaction between xenon and fluorine (molar ratio 1:20) at 700 °C and a pressure of ~200 bar F2. Later systematic studies showed that XeF6 can be prepared under milder conditions (molar ratio 1:10; 200 °C; and a total pressure of 33 bar) [2]. In general, XeF6 is prepared by heating a mixture of Xe and F2 (molar ratio 1:20) at 300 °C and a total pressure of ~50 bar [3]. In the presence of a NiF2 catalyst, XeF6 forms explosively from the gaseous mixture of xenon and fluorine in a molar ratio of 1:5 already at 120 °C [4]. An alternative method with high yield for the preparation of high-purity XeF6 is the reaction between Xe and F2 at low pressure and high filament temperature in a “hot wire” reactor [5]. At room temperature, XeF6 is solid (Tm.p. = 49.48 °C, Tb.p. = 75.57 °C) with a vapor pressure of about 0.03 bar at 23 °C [6]. The color of solid XeF6 has been reported to range from colorless to intense yellow. An explanation for these color variations of solid XeF6 is not apparent to date [7]. Liquid XeF6 and its vapors are yellow-green [6]. There are six, possibly seven, different modifications of solid XeF6 [7]. In CF2Cl2/SO2ClF solution, XeF6 exists as a tetramer (XeF6)4 [8], while in the gas phase XeF6 exists as a monomer [9,10,11]. The presence of a sterically active free valence electron pair on Xe leads to the XeF6 molecule being fluxional [12]. Consequently, the structure of monomeric XeF6 has been a major challenge for theoretical computational chemistry [12,13,14,15,16,17]. Experiments have clearly shown that XeF6 is not octahedral (Oh) but most likely has the shape of a slightly distorted octahedron (C3v), naturally in a dynamical form [18]. Both conformers are energetically very close to each other [15]. Because of the low barrier of interconversion, XeF6 is a highly fluoxinal molecule that rapidly converts between the 8-fold degenerate C3v structures via the octahedral minimum even at low temperatures [15]. In further studies, XeF6 was theoretically shown to exhibit a genuine quantum mechanical fluorine tunneling rearrangement, where it “jumps” rapidly between isomers even near 0 K [16]. In solid argon and neon matrices, there are significant interactions between isolated XeF6 monomers and the noble gas host [15]. The results of infrared spectroscopy of XeF6 in Ne matrix, supported by theoretical calculations, agreed with the C3v conformer [15].
Shortly after the first report on the synthesis of XeF6, it was found that XeF6 is a good fluoride ion donor that reacts with Lewis acids AF5 (A = As, Sb, Pt, V, P) to form nXeF6⋅AF5 adducts [19,20,21,22,23]. Crystal structure determination of XeF6⋅PtF5 revealed a molecular geometry consistent with the ionic formula [XeF5]+[PtF6]− [24]. The compounds XeF6⋅2AF5 are also [XeF5]+ salts [25], while the compounds 2XeF6⋅AF5 are [Xe2F11]+ salts [26,27,28]. The next step was the discovery that XeF5AF6 salts can bind neutral molecules as XeF2 [29,30,31]. Later, this was extended to HF [32], XeOF4 [33], and even KrF2 [32]. Recently, the XeF5SbF6 salt was also found to react with other MSbF6 and M(SbF6)2 salts to give XeF5M(SbF6)2 (M = NO2+, Rb+, Cs+) [28,34], XeF5M(SbF6)3 (M2+ = Mg, Mn, Co, Ni, Cu, Zn, Pd), and (XeF5)3[M(HF)2](SbF6)7 (M = Hg) [34,35] or even more complex salts (H3O)(XeF5)2M2(SbF6)7∙nHF (M = Ca, Cd) [36] and (O2)(XeF5)2Sr4(SbF6)11∙8HF [36] with three different cations. In addition, mixed anion salts Cs[XeF5][BixSb1-xF6] [28] and [XeF5][As1-xSbxF6) (x~0.5 and 0.7) [37] have also been reported.
XeF6 is a stronger oxidizing and fluorinating agent than XeF2 and XeF4. Theoretically, XeF6 could be used as a fluorinating agent. Unfortunately, XeF6 and its XeF5+ salts are very sensitive to moisture. When they are exposed to water, they hydrolyze and eventually form XeO3. The latter is an unstable compound that is extremely sensitive to impact and poses a dangerous explosion hazard when in contact with organic materials. For this reason, XeF6 and its XeF5+ salts currently have no practical significance.
This contribution reports the results of experiments on the preparation of XeF5M(SbF6)3 (M = Sn, Pb), XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn), and XeF5M(AF6)3 salts (M = Cu, Ni; A = Cr, Nb, Ta, Ru, Rh, Re, Os, Ir, Pt, Au, As). The experiments were successful only in the preparation of XeF5Ni(AsF6)3, and many other phases were obtained in other experiments. The crystal structures of XeF5Nb2F11, XeF5TaF6, XeF5Ta2F11, XeF5RhF6, XeF5IrF6, and Ni(XeF2)2(IrF6)2 were determined for the first time. The crystal structures of XeF5NbF6 [30], XeF5PtF6 [24], XeF5RuF6 [38], XeF5AuF6 [39], and (Xe2F11)2(NiF6) [40] were redetermined with higher accuracy than previously reported.

2. Results

2.1. Attempted Preparation of the Salts XeF5M(AF6)3 (M = Cu, Ni; A = Cr, Nb, Ta, Ru, Rh, Re, Os, Ir, Pt, Au, As), XeF5M(SbF6)3 (M = Sn, Pb), and XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn)

The proposed synthetic methods lead to a mixture of substances. The work carried out is an X-ray diffraction study of some crystal phases of these mixtures. In addition, some of the products were also confirmed by Raman spectroscopy (Supplementary Materials).
Reactions between XeF2, MF2 (M = Cu, Ni), AsF5, and UV-irradiated F2 in anhydrous hydrogen fluoride (aHF) resulted in clear colorless (Cu) and yellow (Ni) solutions (Table S1). In the case of nickel, single crystals of XeF5Ni(AsF6)3 were obtained upon crystallization (Table 1), while in the case of copper a mixture of single crystals of XeF5AsF6 [41] and CuFAsF6 [42] was observed in the crystallization product. In all other experiments where mixtures of XeF2/MF2 (M = Ni, Cu) with addition of AF3 (A = Cr, Au), AF5 (A = Nb, Ta), or metal powder A (A = Re, Ru, Rh, Os, Ir, Pt) were treated with UV-irradiated F2 (Table S1), the insoluble material did not disappear even after several days. For crystallization, the clear supernatant, which contained no visible sediments, was decanted into the side arm of the double-arm crystallization vessel. Only single crystals of XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au) and XeF5A2F11 salts (A = Nb, Ta) were grown from the corresponding solutions (Table S1). In the case of Ru and Pt, traces of O2AF6 salts (A = Ru, Pt) [43,44] were also present. Although the remaining insoluble solids were not characterized, it can be assumed that they probably consisted of M(AF6)2 salts (M = Ni, Cu; A = Nb, Ta, Ru, Rh, Ir, Pt, Au). Of these, only Cu(AuF6)2 and Ni(AuF6)2 [45] are known, while the others have not yet been synthesized. Similar to the M[AuF6]2 salts, unlike the M(AF6)2 salts (A = As, Sb) [46], they are probably not well soluble or they are insoluble in anhydrous HF. For the M(AF6)2 salts (M = Ni, Cu; A = Nb, Ta, Ru, Rh, Os, Ir, Pt), their lattice energy appears to overcome the solvation energy. This would explain their insolubility in aHF and the preferential formation of mixtures of M(AF6)2 (insoluble in aHF) and XeF5AF6 (soluble in aHF) instead of XeF5M(AF6)3 salts (M = Cu, Ni; A = Nb, Ta, Ru, Rh, Ir, Pt, Au).
In the XeF2/NiF2/Ir/UV-irradiated F2/aHF system single crystals of XeF5IrF6 and Ni(XeF2)2(IrF6)2 were found in the same batch after crystallization (Table S1). This means that either the F2 concentration was too low to oxidize all of the Xe(II) to Xe(VI), or that partial reduction of Xe(VI) occurred during crystallization.
In the XeF2/NiF2/Re/UV-irradiated F2 system, few single crystals of (Xe2F11)2(NiF6) were detected as crystallization product (Table S1). When pure Re powder is treated with UV-irradiated F2 in aHF, it oxidizes to volatile ReF6 [47]. The latter does not react in aHF even with a very good fluorine ion donor such as CsF [47]. In the XeF2/NiF2/Re/UV-irradiated F2/aHF system, all the Re is oxidized to inert gaseous ReF6. When the NiF2/F2 reaction mixture in aHF is irradiated with UV light, the particles of pale yellow-green NiF2, which is insoluble in aHF, turn black. This indicates that NiF2 is first fluorinated to NiF2+x (x ≤ 1) [47]. When only XeF2 (XeII) is present without other compounds, XeF2 is oxidized to XeIV (XeF4) by elemental fluorine under UV light in aHF [47]. Our experiment has shown that in the presence of Ni(II) and Xe(II) as reagents, oxidation to Ni(IV) and Xe(VI) occurs, giving (Xe2F11)2(NiF6) [40]. The A’2NiF6 salts (A’ = Li, Na, K, Cs) can also be prepared by oxidation of NiF2 at about 20 °C by sunlight or UV-irradiated F2 in liquid aHF containing dissolved alkali metal fluorides (LiF, NaF, KF, CsF) [48].
In the XeF2/CuF2/Os/UV-irradiated F2/HF system, a colorless solution was observed over white insoluble material. Upon cooling the reaction vessel to 77 K, a strong yellow coloration of the solid aHF was observed, indicating the presence of yellow OsF6 [49]. When crystallized from the decanted clear solution, only two small colorless crystals were formed. One of them was detected as XeF4 by Raman spectroscopy, while the other exploded on the diffractometer goniometer.
An attempt to prepare XeF5Cu(CrF6)3 or to detect the formation of XeF5CrF6 salt was unsuccessful. Crystallization yielded only single crystals of (XeF5CrF5)4⋅XeF4 [50]. Although A’CrF6 salts (A’ = Na, K, Rb, Cs) are known [51], the salt XeF5+CrF6− is not. The reaction between CrF5 and XeF6 proceeds at room temperature in aHF with release of fluorine and formation of XeF5CrF5 [52]. In the presence of XeF4, the very stable (XeF5CrF5)4⋅XeF4 is formed [50].
Attempts to prepare XeF5M(SbF6)3 salts (M = Sn, Pb) failed (Table S1). The crystals grown from clear decanted solutions corresponded mainly to XeF5Sb2F11 [25] and XeF5SbF6 [25]. Various approaches to prepare XeF5M(BF4)x(SbF6)3-x salts (x = 1, 2, 3; M = Co, Mn, Ni, Zn) also failed. In the case of Co and Mn, oxidation of M(II) to M(III) occurred, while only crystals of XeF5SbF6 and XeF5Sb2F11 were found between powdered material. In an attempt to prepare (XeF5)Ni(BF4)3, only single crystals of XeF5BF4 [28] were found (Table S1).

2.2. Crystal Structures of the Salts XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), XeF5A2F11 (A = Nb, Ta), (Xe2F11)2(NiF6)2, and Ni(XeF2)2(IrF6)2

Crystal structures were determined on single crystals by X-ray diffraction. Details of the data acquisition parameters and other crystallographic information for the salts XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), XeF5A2F11 (A = Nb, Ta), and (Xe2F11)2(NiF6)2 and Ni(XeF2)2(IrF6)2 are given in Table 1 and Table 2. The crystal structures of XeF5NbF6 [30], XeF5PtF6 [24], XeF5RuF6 [38], XeF5AuF6 [39], and (Xe2F11)2(NiF6) [40] were redetermined at low temperature with higher accuracy than previously reported.
The crystal structures of XeF5AF6 (A = Nb, Ta, Ru, Ir, Pt, Sb) are isotypic. The crystal structures of XeF5AsF6 and XeF5AuF6 are also isotypic, but differ from the previous structures. The crystal structure of XeF5RhF6 is a unique representative of a new type of structure. Some geometric parameters of the XeF5AF6 salts are listed in Table 3 and Table 4.
The crystal structures of XeF5Nb2F11 and XeF5Ta2F11 are not isotypic and they also differ from the previously known crystal structure of XeF5Sb2F11 [25]. Some geometric parameters are listed in Table 5.
The crystal structure of XeF5Ni(AsF6)3 is isotypical to the previously reported crystal structures of XeF5M(SbF6)3 (M2+ = Mg, Mn, Co, Ni, Cu, Zn, Pd) [34,35]. Some geometric parameters are given in Table 6.
The crystal structure of [Ni(XeF2)2](IrF6)2 is isotypical of crystal structure of [Cu(XeF2)2](SbF6)2 reported previously [54]. Some geometric parameters are listed in Table 7.

3. Discussion

3.1. Crystal Structures of XeF5AF6 (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb)

Prior to this study, the crystal structures of XeF5NbF5 (293 K) [30], XeF5RuF5 (RT; room temperature) [38], XeF5PtF5 (RT) [24], XeF5AuF5 (RT) [39], XeF5AsF6 (80 K, 100 K, 150 K, 298 K) [37,41,53], XeF5SbF6 (150 K, 296 K) [25,37], and mixed anion [XeF5][As0.3Sb0.7F6] (200 K, 295 K) and [XeF5][As0.5Sb0.5F6] (150 K, 295 K) salts [37] were known. X-ray powder diffraction (XPD) images showed that XeF5AF6 (A = Os, Ir, Pt, and Ru) are isotypic [39].
The crystal structures of XeF5AF5 (A = Nb, Ru, Pt, Au) determined at 150 K are the same as at room temperature. The crystal structure of XeF5IrF5 agrees with the XPD data [39], while the crystal structures of XeF5TaF6 and XeF5RhF6 have been determined for the first time. Based on the results of this study and the data known from the literature, the crystal structures of the XeF5AF6 salts (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb) can be classified into four types of structures (type I, II, III, and IV).

3.1.1. Type I; XeF5AF6 (A = Nb, Ta, Ru, Os, Ir, Pt, Sb) Salts

The crystal structure of XeF5PtF6 was described as the first example of type I [24]. The crystal structures of the salt XeF5AF6 (A = Nb, Ta, Ru, Os, Ir, Sb) are isotypic to this type (Table 1 and Table 3). The members of type I crystallize in the orthorhombic Pnma space group, in which the asymmetric structural unit consists of a crystallographically unique [XeF5]+ cation and [AF6]− anion (Figure 1).
Each [XeF5]+ cation exhibits the typical geometry, i.e., a pseudo-octahedral AX5E VSEPR arrangement of the bond pairs (X) and the lone pair (E). The Xe–Fax bonds are shorter than the other four Xe–Feq distances (Table 4, Figure 2). Each XeF5 unit forms four secondary contacts with the fluorine atoms of four AF6 groups (Figure 2). Each [AF6]− anion participates in four secondary contacts with four different XeF5 groups (Figure 2).

3.1.2. Type II; XeF5AF5 (A = As, Au) Salts

The crystal structures of XeF5AuF6 and the monoclinic form of XeF5AsF6 are examples of type II (Table 1 and Table 4). They crystallize in the monoclinic space group P21/c. The asymmetric structural unit of type II consists of a crystallographically equivalent [XeF5]+ cation and an [AF6]− anion (Figure 3).
The geometry of the [XeF5]+ in the salts of type II is the same as in type I [d(Xe–Fax) < d(Xe–Feq); Table 4, Figure 4), while the number of secondary contacts between [XeF5]+ cations and [AF6]− anions is different. In type II, each [XeF5]+ cation forms three secondary contacts with the fluorine atoms of two AF6 groups and each [AF6]− anion participates in three secondary contacts with two different XeF5 groups (Figure 4).

3.1.3. Type III; XeF5AF5 (A = Rh) Salts

The crystal structure of XeF5RhF6 is the only representative of type III (Table 1 and Table 4). It crystallizes in the orthorhombic space group Pbca. The asymmetric structural unit of type III consists of a crystallographically equivalent [XeF5]+ cation and an [AF6]− anion (Figure 5).
The geometry of the [XeF5]+ in the type III salts is similar to that in the type I and II compounds (d(Xe–Fax) < d(Xe–Feq); Table 4, Figure 6), while the nature of the secondary interaction contacts between the [XeF5]+ cations and the [AF6]− anions is different. In type III, each [XeF5]+ cation forms four secondary contacts with the fluorine atoms of three AF6 groups, while each [AF6]− anion participates in four secondary contacts with three different XeF5 groups (Figure 6).

3.1.4. Type IV; Orthorhombic XeF5AsF6 and Mixed Anionic [XeF5][As0.3Sb0.7F6) and [XeF5][As0.5Sb0.5F6) Salts

The crystal structure of XeF5AsF6 was first determined at room temperature [41] and later redetermined at 150 K [37]. When the crystal first measured at 150 K was cooled to 80 K and data were collected, no phase transition was observed [37]. In both cases, only a monoclinic phase was obtained (150 K; P21/c, Z = 4, a = 5.8222 (6) Å, b = 16.3566 (15) Å, c = 7.9247 (8) Å, β = 90.729 (9) o). However, single crystals of orthorhombic XeF5AsF6 (Table 8) crystallized from aHF solution between 22 and −30 °C [53]. The corresponding aHF solution was prepared by redox decomposition of [FKrFXeF][AsF6]⋅0.5KrF2⋅2HF heated stepwise and four different times, from −65 °C to 22 °C. The asymmetric structural unit consists of two crystallographically nonequivalent [XeF5]+ cations and two [AsF6]− anions [53].
Similar unit cell parameters (Table 8) were determined for orthorhombic [XeF5][As0.3Sb0.7F6] (100–295 K) and β-[XeF5][As0.5Sb0.5F6] (295 K), both of which have a (3 + 1)-dimensional incommensurately modulated crystal structure (superspace group Ama2(00γ)s0s) [37]. At 150 K, the α-[XeF5][As0.5Sb0.5F6] salt is also orthorhombic, but not modulated (space group Pca21) and with doubled c-axis (Table 8) [37]. In [XeF5][As0.3Sb0.7F6] and β-[XeF5][As0.5Sb0.5F6] there are two crystallographically nonequivalent [XeF5]+ cations and two crystallographically independent sites for pnictogen atoms, while in α-[XeF5][As0.5Sb0.5F6] there are four crystallographically nonequivalent [XeF5]+ cations and four crystallographically different sites for pnictogen atoms.
All the compounds listed in Table 8 are structurally related, as indicated by the similar packing in their crystal structures (Figure 7). It is practically identical in the orthorhombic XeF5AsF6, [XeF5][As0.3Sb0.7F6], and β-[XeF5][As0.5Sb0.5F6] and slightly different in α-[XeF5][As0.5Sb0.5F6] due to the different inclination of some AF6 (A = As, Sb)octahedra.
In the orthorhombic [XeF5][AsF6] [53] each [Xe(1)F5]+ cation forms three shorter (<3 Å) and one longer secondary contact (3.451 (7) Å) with the fluorine atoms of four AsF6 groups. The sum of the Xe···F van der Waals radii is 3.63 Å [55]. The other [Xe(2)F5]+ cation is also involved in four secondary interactions (<3 Å), but only with three AsF6 groups. Each [As(1)F6]− anion interacts with four [XeF5]+ cations and each [As(2)F6]− anion interacts with only three [XeF5]+ cations (Figure 8).
In α-[XeF5][As0.5Sb0.5F6] [37], the cations [Xe(1)F5]+ and [Xe(2)F5]+ each form four secondary contacts (<3 Å) with the fluorine atoms of three AF6 groups (A = As, Sb), while [Xe(3)F5]+ and [Xe(4)F5]+ have three shorter (<3 Å) and one longer (3.437(7) Å and 3.420(7) Å, respectively) contact with four AF6 groups (Figure 9). Each of the crystallographically unique [A(1)F6]− and [A(2)F6]− anions forms four interactions with three [XeF5]+ cations, while the [A(3)F6]− and [A(4)F6]− anions form four interactions with four [XeF5]+ cations, (Figure 10).

3.1.5. General Considerations for XeF5AF6 Salts (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb)

Table 9 lists the effective ionic radii r(A5+) (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb) for coordination number six [56], the formula units (molecular) volumes VFU of LiAF6, CsAF6, and XeF5AF6, and the average A–F bond lengths in LiAF6 and XeF5AF6. The molecular volumes of LiAF6, CsAF6, and XeF5AF6 are shown in Figure 11. The crystal structures of LiAF6 (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, and Au) were determined by synchrotron X-ray powder diffraction at 299 K [57]. The crystal structures of LiAsF6 and LiSbF6 were determined by X-ray diffraction on powdered material and single crystals, respectively, at room temperature (RT) [58,59]. With the exception of CsAsF6 and CsSbF6, whose complete crystal structures were determined on single crystals at RT, only unit cells determined at RT are available for the other CsAF6 salts [60]. The crystal structures of CsAF6 (A = Rh, Pt, Ir, Os, and Au) were also determined on single crystals at 150 K [61]. The crystal structures of XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au, As [37], Sb [25]) were determined at 150 K and some of them also at RT (A = As [41], Au [39], Pt [24], Ru [38], Sb [37], Nb [30]).
Although the formula unit volumes VFU of the LiAF6 and CsAF6 salts (Figure 11) show a similar trend, this is not the case for the XeF5AF6 salts, with the VFU of XeF5RhF6 and XeF5AuF6 being particularly prominent. For LiAF6 and CsAF6, the VFU are smallest for the As, Rh, and Au salts and largest for the Sb, Nb, and Ta salts. For the [XeF5]+ salts, the VFU of XeF5AuF6 is almost identical to the VFU of XeF5TaF6, while XeF5RhF6 has the smallest value VFU of all XeF5AF6 salts (Table 9, Figure 11).

3.2. Crystal Structures of XeF5A2F11 (A = Nb, Ta, Sb)

In the XeF6–AF5 (A = Nb, Ta) system, only the salts XeF5AF6 and Xe2F11AF6 have been known so far [30,62,63]. The salts XeF5Nb2F11 and XeF5Ta2F11 were prepared for the first time in this study. As in the case of XeF5Sb2F11 [25] (Figure 12) the crystal structures of XeF5A2F11 (A = Nb, Ta) consist of discrete [XeF5]+ cations and dimeric [A2F11]− anions interacting through secondary fluorine bridge Xe⋅⋅⋅F–A contacts (Figure 13 and Figure 14). Each crystal structure of the XeF5A2F11 salts (A = Sb, Nb, Ta) represents a unique example (Table 2 and Table 5).
In XeF5Nb2F11, each [XeF5]+ cation forms three secondary contacts with the fluorine atoms of two Nb2F11 groups, whereas in XeF5Sb2F11 and XeF5Ta2F11, each [A2F11]− anion (A = Nb, Ta) participates in four secondary contacts with three different A2F11 dimers (Figure 12, Figure 13 and Figure 14). In all three salts, the Xe–Fax bonds are shorter than the other four Xe–Feq distances (Table 5). The A–Fb–A bridge (Table 5) in the dimeric [A2F11]− anion (A = Sb, Nb, Ta) is not linear as in [A2F11]− (M = Nb, Ta) salts of protonated 1,3-dimethoxybenzene but bent as in many other examples [64]. In XeF5Sb2F11, the four Feq atoms of the Sb(1)F6 unit are in staggered position in respect to the four Feq of the Sb(2)F6 group with a torsion angle of ~37.5 o, while in the corresponding Nb and Ta salts they are almost in an eclipsed position.

3.3. Crystal Structure of XeF5Ni(AsF6)3

The crystal structure of XeF5Ni(AsF6)3 (Figure 15) is isotypical to the crystal structure of XeF5Ni(SbF6)3 [35]. The cation Ni2+ is coordinated by six fluorine atoms provided by six octahedral anions [AsF6]− forming almost regular NiF6 octahedra. The Ni−F bond lengths in both salts are virtually identical (Table 6). They range from 1.989 (1) to 2.013 (1) Å. Due to the sharing of fluorine atoms, the NiF6 and AsF6 octahedra are connected to form a three-dimensional framework. The [XeF5]+ cations are located inside the cavities. The geometry of the [XeF5]+ cations is almost identical in both Ni salts (Table 5).

3.4. Crystal Structures of the Salts (Xe2F11)2(NiF6)2 and Ni(XeF2)2(IrF6)2

The crystal structure of (Xe2F11)2(NiF6)2 determined at 150 K is the same as that at room temperature [40], which means that there is no phase transition in the 150–296 K range.
It has been reported that the reaction between Mn+(AF6)n− and XeF2 in anhydrous aHF (aHF) leads to coordination compounds [Mn+(XeF2)p](AF6)n− (where XeF2 is coordinated to a metal cation Mn+) only when the Lewis acidity of Mn+ is not high enough to withdraw F− ions from XeF2 to form MFn and Xe2F3+AF6− [65]. Since the reaction between Ni(AsF6)2 and XeF2 in aHF gave NiF2 and Xe2F3AsF6, the preparation of [Ni(XeF2)2](IrF6)2 was a small surprise.
The crystal structure of [Ni(XeF2)2](IrF6)2 is isotypical to the crystal structure of [Cu(XeF2)2](SbF6)2 [54]. In both structures, adjacent [M(XeF2)2]2+ units are connected via two [AF6]− units with bridging fluorine atoms in the cis position to form infinite chains that are parallel to the x–axis (Figure 16). These chains are interconnected by weak F2Xe···F–AF5 contacts and form a three-dimensional network.
The metal cation Ni2+ is sixfold coordinated by fluorine atoms of two XeF2 ligands and four [IrF6]− anions. In [Cu(XeF2)2](SbF6)2, the Cu2+ cation is coordinated by two XeF2 molecules (Cu–F = 2 × 1.857 (5) Å) and four fluorine atoms provided by four [SbF6] units with two shorter and two longer Cu–F bonds (2 × 2.090 (5) Å and 2 × 2.123 (5) Å) [54]. In contrast, the Ni–F(Ir) bonds in the Ni(XeF2)2(IrF6)2 salt are almost the same length (2 × 2.016 (9) Å and 2 × 2.023 (7) Å). The Ni–F(XeF2) bonds are much longer (2 × 1.938(6) Å) than in the [Cu(XeF2)2](SbF6)2 salt (2 × 1.857 (5) Å), indicating a weaker M2+–FXeF interaction in the Ni salt. Consequently, Xe–Fb (Fb = bridging F atom) is shorter (2.078 (6) Å) in the Ni salt than in the Cu salt (2.102 (5) Å) and the opposite is true for Xe−Ft bonds [Ft = terminal fluorine atom; 1.920 (7) Å (Ni salt) and 1.906 (5) Å (Cu salt)].

4. Materials and Methods

CAUTION: Anhydrous HF and some fluorides are highly toxic and must be handled under a well-ventilated hood, and protective clothing must be worn at all times!

4.1. Apparatus, Techniques, and Reagents

The handling of volatile (anhydrous HF, F2, AsF5, BF3) and nonvolatile materials and the type of the reaction and crystallization vessels have already been reported [35,47,66]. Metallic Re powder (Alfa Aesar, Haverhill, MA, USA, 99.99%), Ru sponge (Alfa Aesar, 99.95%), Rh sponge (BDH, 99.9%), Os powder (Alfa Aesar, 99.8%), Ir sponge (Alfa Aesar, 99.95%), Pt powder (Aldrich, St. Louis, MO, USA, 99.9%), elemental F2 (Solvay Fluor and Derivate GmbH, Hannover, Germany 99.98%), CrF3 (Messer Griesheim, Bad Soden, Germany, 99.9%), and BF3 (Union Carbide Austria, GmbH, 99.5%) were used as supplied. Anhydrous HF (Linde AG, Pullach, Germany, 99.995%) was treated with K2NiF6 (Advance Research Chemicals Inc, Catoosa, OK, USA, 99.9%) for several hours before use. NiF2 (Alfa Products, Bedford Park, IL, USA, 99.5%) and CuF2 (Aldrich, 98%) were treated with elemental F2 at 220 °C for several hours before use. NbF5 (Alfa Aesar, 99%) and TaF5 (Alfa Aesar, 99.9%) were sublimed before use. AuF3 [66], XeF2 [67], AsF5 [68], XeF5SbF6 [34], Sn(SbF6)2 [69,70], Pb(SbF6)2 [69,70], and Zn(SbF6)2 [69,70] were synthesized as described previously.
Raman spectra were recorded at room temperature using a Renishaw Raman Imaging Microscope System 1000 or a Horiba Jobin Yvon LabRam-HR spectrometer [66].

4.2. Attempted Preparation of XeF5M(AF6)3 (M = Cu, Ni; A = Cr, Nb, Ta, Ru, Rh, Re, Os, Ir, Pt, Au, As), XeF5M(SbF6)3 (M = Sn, Pb), and XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn)

The solid starting reagents were loaded into reaction vessels in a dry box (Table S1). The solvent HF and optionally BF3, AsF5, and SbF5 were condensed at 77 K to solid reagents, and the reaction vessel was warmed to ambient temperature. Fluorine was slowly added to the reaction vessel at room temperature. A medium-pressure mercury lamp (Hg arc lamp, 450 W, Ace Glass, Vineland, NJ, USA) was used as the UV source. After several days of intensive stirring at room temperature, the volatiles were pumped off and the Raman spectra of the obtained solids were recorded (Figures S1–S11).
For crystallization, the clear supernatant, which contained no visible sediment, was decanted into the side arm of the crystallization vessel, which consisted of two tubes made of fluoropolymer. Evaporation of the solvent from the side arm was achieved by maintaining a temperature gradient of about 10–20 °C between the two tubes for several weeks. Slow distillation of aHF resulted in crystal growth.
Crystals were immersed in perfluorodecalin (melting point 263 K) in a dry box, selected under the microscope, and mounted on the goniometer head of the diffractometer in a cold nitrogen stream (265–273 K). Some of them were sealed in quartz capillaries used to record Raman spectra at several random positions (Figures S1–S11).

4.3. Crystal Structure Determination

Single-crystal X-ray diffraction data of reported crystal structures were acquired at 150 K (for XeF5IrF6 also at 285 K) with a Gemini A diffractometer equipped with an Atlas CCD detector using graphite monochromated MoKα radiation. The data were processed using the CrysAlisPro software suite program package [71]. Analytical absorption corrections were applied to all data sets. All structures were solved using the dual-space algorithm of the program SHELXT [72] implemented in the Olex crystallographic software [73]. Structure refinement for all structures was performed using the software SHELXL-2014 [74]. The crystals of the Ni(XeF2)2(IrF6)2 salt showed reproducible pseudo-merohedral twinning. This problem was solved at the data processing stage, and final refinement was performed using reflections from the main domain. The figures were created using the software Balls and Sticks [75]. The compound XeF5Nb2F11 crystallizes in the acentric space group P21. The very-close-to-zero value of the Flack’s parameter (−0.031 (11)) confirms the correctness of the absolute structure.
The supplementary crystallographic data for this work are provided free of charge by the joint Cambridge Crystallographic Data Centre and the Fachinformationszentrum Karlsruhe Access Structures service www.ccdc.cam.ac.uk/structures (accessed on March 10, 2023): CSD-2246135 [(Xe2F11)2NiF6], CSD-2246136 [Ni(XeF2)2(IrF6)2], CSD-2246137 [XeF5AuF6], CSD-2246138 [XeF5IrF6, 150 K], CSD-2246139 [XeF5Nb2F11], CSD-2246140 [XeF5PtF6], CSD-2246141 [XeF5RuF6], CSD-2246142 [XeF5IrF6, 280 K], CSD-2246143 [XeF5Ta2F11], CSD-2246144 [XeF5NbF6], CSD-2246145 [XeF5Ni(AsF6)3], CSD-2246146 [XeF5TaF6], CSD-2246147 [XeF5RhF6].

5. Conclusions

Although the experiments to prepare XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn), XeF5M(SbF6)3 (M = Sn, Pb), and XeF5M(AF6)3 salts (M = Cu, Ni; A = Cr, Nb, Ta, Ru, Rh, Re, Os, Ir, Pt, Au, As) were successful only in the preparation of XeF5Ni(AsF6)3, further valuable results were obtained:
(a)
In view of the successful preparation of XeF5Ni(AsF6)3, we assume that it is reasonable to attempt the preparation of other compounds with other M2+ cations (M = Mg, Fe, Co, Zn, etc.).
(b)
Crystal structure determination of XeF5RhF6 reveals a new type of structure. Together with the crystal structures of XeF5TaF6 and XeF5IrF6, which were determined for the first time, and the redetermined crystal structures of XeF5NbF6, XeF5PtF6, XeF5RuF6, and XeF5AuF6, they contribute to the understanding of the possible crystal phases in the family of XeF5AF5 salts.
(c)
The crystal structures of the XeF5Nb2F11 and XeF5Ta2F11 salts were determined. These compounds were previously unknown, and for the XeF5A2F11 salts, only the crystal structure of XeF5Sb2F11 [25] was known. These three [A2F11]− salts are not isotypic and each of them represents a unique structural type.
(d)
The crystal structure of XeF5IrF6 determined at 150 K and at room temperature is identical. The crystal structures of the salts XeF5NbF6, XeF5PtF6, XeF5RuF6, XeF5AuF6, XeF5AsF6 [37], and (Xe2F11)2NiF6 redetermined at 150 K are also identical to those determined at room temperature, indicating that there is no phase transition in the range from 150 K to 298 K.
(e)
All the new data on the XeF5AF6 and XeF5A2F11 salts help to fill the gaps in our knowledge of the XeF6-AVF5 system (Table 10).
(f)
The preparation of Ni(XeF2)2(IrF6)2 has shown that it is worthwhile to try the preparation of some other [Mn+(XeF2)p](AF6)n− salts (A = Rh, Ru, Os, Ir, Pt, Au, Nb, Ta) where attempts to stabilize such salts with [AF6]− (A = As, Sb) have failed.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/molecules28083370/s1, Table S1: Experimental conditions and observed products upon crystallization for the reactions between UV-irradiated F2, XeF2, MF2 (M = Cu, Ni) and metal A (A = Ru, Rh, Re, Os, Ir, Pt), MF3 (A = Cr, Au), and AF5 (M = Nb, Ta, As), respectively, in anhydrous HF. The products observed upon crystallization and the experimental conditions for the reactions between XeF5SbF6 and M(SbF6)2 (M = Sn, Pb) are also given.; Table S2: Experimental conditions and observed products upon crystallization in the experiments to prepare XeF5M(BF4)x(SbF6)3-x (x = 1, 2, 3; M = Co, Mn, Ni, Zn) salts.; Figures S1–S10. Raman spectra of XeF5NbF6, XeF5TaF6, XeF5RhF6, XeF5RuF6, XeF5IrF6, XeF5PtF6, XeF5Nb2F11, XeF5Ta2F11, O2PtF6, and O2RuF6 recorded on a single crystal; Figure S11. Raman spectra of single crystals after crystallization of the reaction product between XeF2, Os powder and UV-irradiated F2 in anhydrous HF: XeF4 and unknown product.

Author Contributions

Conceptualization, Z.M.; formal analysis, Z.M. and E.G.; investigation, Z.M. and E.G.; writing—original draft preparation; visualization, Z.M.; All authors have read and agreed to the published version of the manuscript.

Funding

The authors gratefully acknowledge financial support of the Slovenian Research Agency (research core funding No. P1–0045; Inorganic Chemistry and Technology).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

Sample Availability

Samples of the compounds are available from the authors.

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Molecules 28 03370 g001 550
Figure 1. Two different views of the packing of [XeF5]+ cations and [IrF6]− anions in the crystal structure of [XeF5][IrF6] (type I).
Figure 1. Two different views of the packing of [XeF5]+ cations and [IrF6]− anions in the crystal structure of [XeF5][IrF6] (type I).
Molecules 28 03370 g001
Molecules 28 03370 g002 550
Figure 2. Secondary contacts between the [XeF5]+ cations and [IrF6]− anions in the crystal structure of [XeF5][IrF6] (type I).
Figure 2. Secondary contacts between the [XeF5]+ cations and [IrF6]− anions in the crystal structure of [XeF5][IrF6] (type I).
Molecules 28 03370 g002
Molecules 28 03370 g003 550
Figure 3. Two different views of the packing of [XeF5]+ cations and [AuF6]− anions in the crystal structure of [XeF5][AuF6] (type II).
Figure 3. Two different views of the packing of [XeF5]+ cations and [AuF6]− anions in the crystal structure of [XeF5][AuF6] (type II).
Molecules 28 03370 g003
Molecules 28 03370 g004 550
Figure 4. Secondary contacts between the [XeF5]+ cations and [AuF6]− anions in the crystal structure of [XeF5][AuF6] (type II).
Figure 4. Secondary contacts between the [XeF5]+ cations and [AuF6]− anions in the crystal structure of [XeF5][AuF6] (type II).
Molecules 28 03370 g004
Molecules 28 03370 g005 550
Figure 5. Two different views of the packing of [XeF5]+ cations and [RhF6]− anions in the crystal structure of [XeF5][RhF6] (type III).
Figure 5. Two different views of the packing of [XeF5]+ cations and [RhF6]− anions in the crystal structure of [XeF5][RhF6] (type III).
Molecules 28 03370 g005
Molecules 28 03370 g006 550
Figure 6. Secondary contacts between the [XeF5]+ cations and [RhF6]− anions in the crystal structure of [XeF5][RhF6] (type III).
Figure 6. Secondary contacts between the [XeF5]+ cations and [RhF6]− anions in the crystal structure of [XeF5][RhF6] (type III).
Molecules 28 03370 g006
Molecules 28 03370 g007 550
Figure 7. Packing of [XeF5]+ cations and [AF6]− anions (A = As, Sb) in the crystal structures of (a) orthorhombic [XeF5][AsF6]; (b) α-[XeF5][As0.5Sb0.5F6]; (c) average structure of [XeF5][As0.3Sb0.7F6]. The last figure is reproduced from Ref. [37] and published under the terms and conditions of the Creative Commons Attribution 4.0 International License CC BY 4.0.
Figure 7. Packing of [XeF5]+ cations and [AF6]− anions (A = As, Sb) in the crystal structures of (a) orthorhombic [XeF5][AsF6]; (b) α-[XeF5][As0.5Sb0.5F6]; (c) average structure of [XeF5][As0.3Sb0.7F6]. The last figure is reproduced from Ref. [37] and published under the terms and conditions of the Creative Commons Attribution 4.0 International License CC BY 4.0.
Molecules 28 03370 g007
Molecules 28 03370 g008 550
Figure 8. Secondary contacts between the [XeF5]+ cations and the [AsF6]− anions in the crystal structure of orthorhombic [XeF5][AsF6] (type IV).
Figure 8. Secondary contacts between the [XeF5]+ cations and the [AsF6]− anions in the crystal structure of orthorhombic [XeF5][AsF6] (type IV).
Molecules 28 03370 g008
Molecules 28 03370 g009 550
Figure 9. Secondary contacts between the [XeF5]+ cations and the surrounding [AF6]− anions (A = As, Sb) in the crystal structure of α-[XeF5][As0.5Sb0.5F6].
Figure 9. Secondary contacts between the [XeF5]+ cations and the surrounding [AF6]− anions (A = As, Sb) in the crystal structure of α-[XeF5][As0.5Sb0.5F6].
Molecules 28 03370 g009
Molecules 28 03370 g010 550
Figure 10. Secondary contacts between the [AF6]− (A = As, Sb) anions and the surrounding [XeF5]+ cations in the crystal structure of α-[XeF5][As0.5Sb0.5F6].
Figure 10. Secondary contacts between the [AF6]− (A = As, Sb) anions and the surrounding [XeF5]+ cations in the crystal structure of α-[XeF5][As0.5Sb0.5F6].
Molecules 28 03370 g010
Molecules 28 03370 g011 550
Figure 11. Formula unit volumes of LiAF6 (for A = Rh, Au, Pt, Ir, Ru, Os, Nb, Ta at 299 K and for A = As, Sb at room temperature), CsAF6 (all data at room temperature), and XeF5AF6 salts (all data at 150 K).
Figure 11. Formula unit volumes of LiAF6 (for A = Rh, Au, Pt, Ir, Ru, Os, Nb, Ta at 299 K and for A = As, Sb at room temperature), CsAF6 (all data at room temperature), and XeF5AF6 salts (all data at 150 K).
Molecules 28 03370 g011
Molecules 28 03370 g012 550
Figure 12. Secondary contacts between the [XeF5]+ cations and the [Sb2F11]− anions in the crystal structure of XeF5Sb2F11.
Figure 12. Secondary contacts between the [XeF5]+ cations and the [Sb2F11]− anions in the crystal structure of XeF5Sb2F11.
Molecules 28 03370 g012
Molecules 28 03370 g013 550
Figure 13. Secondary contacts between the [XeF5]+ cations and the [Nb2F11]− anions in the crystal structure of XeF5Nb2F11.
Figure 13. Secondary contacts between the [XeF5]+ cations and the [Nb2F11]− anions in the crystal structure of XeF5Nb2F11.
Molecules 28 03370 g013
Molecules 28 03370 g014 550
Figure 14. Secondary contacts between the [XeF5]+ cations and the [Ta2F11]− anions in the crystal structure of XeF5Ta2F11.
Figure 14. Secondary contacts between the [XeF5]+ cations and the [Ta2F11]− anions in the crystal structure of XeF5Ta2F11.
Molecules 28 03370 g014
Molecules 28 03370 g015 550
Figure 15. Part of the crystal structure of XeF5Ni(AsF6)3.
Figure 15. Part of the crystal structure of XeF5Ni(AsF6)3.
Molecules 28 03370 g015
Molecules 28 03370 g016 550
Figure 16. Part of the crystal structure of [Ni(XeF2)2](IrF6)2.
Figure 16. Part of the crystal structure of [Ni(XeF2)2](IrF6)2.
Molecules 28 03370 g016
Table
Table 1. Summary of crystal data and refinement results for XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au).
Table 1. Summary of crystal data and refinement results for XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au).
FormulaXeF5NbF6XeF5TaF6XeF5RuF6XeF5RhF6
T (K)150150150150
Crystal SystemOrthorhombicOrthorhombicOrthorhombicOrthorhombic
Space GroupPnmaPnmaPnmaPbca
a (Å)16.8078 (10)16.8312 (12)16.6197 (12)9.0028 (4)
b (Å)8.2491 (6)8.2399 (6)8.0530 (6)8.8181 (4)
c (Å)5.6064 (3)5.6488 (4)5.6373 (4)18.2581 (8)
V (Å3)777.32 (8)783.41 (10)754.49 (9)1449.47 (11)
Z4448
Dcalcd (g/cm3)3.7024.4193.8864.062
λ (Å)0.710730.710730.710730.71073
μ (mm−1)5.98818.4366.6527.118
GOF a1.0911.0521.1091.044
R1 b0.02530.03550.02440.0226
wR2 c0.05030.07570.05210.0430
FormulaXeF5IrF6XeF5IrF6XeF5PtF6XeF5AuF6
T (K)150285150150
Crystal SystemOrthorhombicOrthorhombicOrthorhombicMonoclinic
Space GroupPnmaPnmaPnmaP21/c
a (Å)16.5720 (10)16.7456 (14)16.5286 (13)5.8447 (5)
b (Å)7.9954 (5)8.1444 (8)7.9642 (5)16.6324 (10)
c (Å)5.7412 (4)5.6998 (6)5.7779 (5)8.0536 (5)
β (o) 90.781 (6)
V (Å3)760.71 (8)777.35 (13)760.58 (10)782.82 (9)
Z4444
Dcalcd (g/cm3)4.6504.5504.6754.559
λ (Å)0.710730.710730.710730.71073
μ (mm−1)22.08821.61522.98623.202
GOF a1.0811.1741.0781.064
R1 b0.02670.03980.02470.0364
wR2 c0.04910.08150.04450.0798
a GOF = [Σw(Fo2 − Fc2)2/(No − Np)]1/2, where No = no. of reflns and Np = no. of refined parameters. b R1 = Σ׀׀Fo׀ − ׀Fc׀׀/Σ׀Fo׀. c wR2 = [Σw(Fo2 − Fc2)2/Σ(w(Fo2)2]1/2.
Table
Table 2. Summary of crystal data and refinement results for XeF5A2F11 (A = Nb, Ta), XeF5Ni(AsF6)3, (Xe2F11)2(NiF6)2, and Ni(XeF2)2(IrF6)2.
Table 2. Summary of crystal data and refinement results for XeF5A2F11 (A = Nb, Ta), XeF5Ni(AsF6)3, (Xe2F11)2(NiF6)2, and Ni(XeF2)2(IrF6)2.
FormulaXeF5Nb2F11XeF5Ta2F11XeF5Ni(AsF6)3(Xe2F11)2(NiF6)2Ni(XeF2)2(IrF6)2
T (K)150150150150150
Crystal SystemMonoclinicMonoclinicMonoclinicMonoclinicMonoclinic
Space GroupP21I2/aP21/nI2/cP21/c
a (Å)5.2717 (2)8.9972 (5)10.2200 (3)17.2498 (11)5.43790 (10)
b (Å)14.1920 (5)9.3302 (5)10.1973 (3)5.3239 (3)14.6396 (5)
c (Å)7.6489 (2)14.0691 (8)14.5606 (4)21.0164 (11)9.1039 (3)
β (o)92.412 (3)99.281 (5)90.072 (2)102.510 (6)92.003 (2)
V (Å3)571.75 (3)1165.58 (11)1517.45 (8)1884.3 (2)724.31 (4)
Z24442
Dcalcd (g/cm3)3.6084.5433.7283.9344.630
λ (Å)0.710730.710730.710730.710730.71073
μ (mm−1)5.11521.81410.2168.35824.375
GOF a1.0561.0571.0621.0451.072
R1 b0.02050.02730.02690.02140.0429
wR2 c0.04270.06650.05630.04630.1305
a GOF = [Σw(Fo2 − Fc2)2/(No − Np)]1/2, where No = no. of reflns and Np = no. of refined parameters. b R1 = Σ׀׀Fo׀ − ׀Fc׀׀/Σ׀Fo׀. c wR2 = [Σw(Fo2 − Fc2)2/Σ(w(Fo2)2]1/2.
Table
Table 3. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F bond lengths (Å) in the crystal structures of isotypic XeF5AF6 (A = Nb, Ta, Ru, Ir, Pt, Au) and literature data for XeF5SbF6.
Table 3. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F bond lengths (Å) in the crystal structures of isotypic XeF5AF6 (A = Nb, Ta, Ru, Ir, Pt, Au) and literature data for XeF5SbF6.
Nb aTa aRu aIr aPt aSb b
Orthorhombic Pnma
150 K150 K150 K150 K150 K150 K
Xe–Fax1.808 (3)1.803 (7)1.807 (3)1.809 (5)1.809 (5)1.804 (3)
Xe–Feq1.839 (2)1.839 (5)1.843 (2)1.835 (3)1.838 (3)1.841 (2)
1.839 (2)1.839 (5)1.843 (2)1.835 (3)1.838 (3)1.841 (2)
1.842 (2)1.843 (5)1.846 (2)1.843 (3)1.839 (3)1.844 (2)
1.842 (2)1.843 (5)1.846 (2)1.843 (3)1.839 (3)1.844 (2)
Xe···F2.540 (3)2.562 (6)2.562 (3)2.602 (5)2.604 (5)2.617 (3)
2.535 (2)2.560 (6)2.587 (3)2.616 (4)2.646 (4)2.638 (3)
2.887 (2)2.894 (5)2.856 (2)2.822 (3)2.817 (3)2.860 (2)
2.887 (2)2.894 (5)2.857 (3)2.822 (3)2.817 (3)2.860 (2)
A–F1.835 (3)1.849 (7)1.820 (3)1.841 (5)1.857 (4)1.857 (3)
1.852 (3)1.873 (7)1.823 (3)1.861 (5)1.871 (4)1.859 (3)
1.886 (2)1.880 (5)1.854 (3)1.879 (3)1.884 (3)1.882 (2)
1.886 (2)1.880 (5)1.854 (3)1.879 (3)1.884 (3)1.882 (2)
1.925 (3)1.930 (6)1.878 (3)1.892 (4)1.894 (4)1.895 (3)
1.941 (3)1.939 (6)1.885 (3)1.906 (5)1.897 (4)1.898 (3)
a This work. b Ref. [25].
Table
Table 4. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F bond lengths (Å) in the crystal structures of XeF5AF6 (A = Rh, Au) and literature data for XeF5AsF6 (monoclinic and orthorhombic phase).
Table 4. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F bond lengths (Å) in the crystal structures of XeF5AF6 (A = Rh, Au) and literature data for XeF5AsF6 (monoclinic and orthorhombic phase).
Rh aAu aAs bAs c
Orthorhombic PbcaMonoclinic P21/cMonoclinic P21/cOrthorhombic Ama2
150 K150 K150 K100 K
Xe (2)/Xe (1)
Xe–Fax1.814 (2)1.804 (5)1.794 (3)1.815 (7)/1.800 (8)
Xe–Feq1.833 (2)1.823 (6)1.826 (3)1.844 (5)/1.840 (6)
1.841 (2)1.834 (6)1.828 (3)1.833 (8)/1.838 (6)
1.842 (2)1.835 (5)1.833 (3)1.833 (8)/1.838 (6)
1.842 (2)1.836 (5)1.836 (3)1.832 (8)/1.840 (6)
Xe···F2.603 (2)2.575 (6)2.643 (3)2.705 (5)/2.615 (6)
2.664 (2)2.746 (5)2.722 (3)2.705 (5)/2.615 (6)
2.761 (2)2.785 (6)2.782 (3)2.767 (6)/2.796 (6)
2.844 (2) 2.767 (6)/3.451 (7)
As (2)/As (1)
A–F1.871 (2)1.872 (6)1.688 (3)1.709 (5)/1.657 (7)
1.873 (2)1.876 (5)1.696 (3)1.709 (5)/1.657 (7)
1.874 (2)1.884 (5)1.696 (3)1.741 (6)/1.699 (6)
1.879 (2)1.903 (5)1.738 (3)1.749 (5)/1.699 (6)
1.799 (2)1.910 (5)1.744 (3)1.749 (5)/1.712 (6)
1.815 (2)1.911 (5)1.750 (3)1.710 (7)/1.712 (6)
a This work. b Ref. [37]. c Ref. [53].
Table
Table 5. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F (A = Nb, Ta) bond lengths (Å) and A–Fb–A angles (o) in the crystal structures of XeF5A2F11 (A = Nb, Ta) and literature data for XeF5Sb2F11.
Table 5. Geometric parameters (Å) of the [XeF5]+ cations, secondary Xe···F contacts (Å), and A–F (A = Nb, Ta) bond lengths (Å) and A–Fb–A angles (o) in the crystal structures of XeF5A2F11 (A = Nb, Ta) and literature data for XeF5Sb2F11.
Nb aTa aSb b
Monoclinic P21Monoclinic I2/aTriclinic P 1 ¯
150 K150 K200 K
Xe–Fax1.801 (3)1.802 (6)1.883 (3)
Xe–Feq1.826 (3)1.838 (3)2.019 (3)
1.836 (3)1.838 (3)2.029 (3)
1.837 (3)1.839 (4)1.837 (3)
1.838 (4)1.839 (4)1.838 (3)
Xe···F2.582 (3)2.666 (4)2.915 (3)
2.633 (3)2.872 (3)2.848 (3)
2.667 (3)2.872 (3)2.775 (3)
2.814 (3)
A (1)–Ft1.823 (3)1.824 (4)1.838 (3)
1.840 (4)1.849 (4)1.846 (3)
1.846 (4)1.855 (4)1.853 (3)
1.847 (4)1.900 (4)1.866 (3)
1.918 (3)1.910 (4)1.883 (3)
A (1)–Fb2.096 (3)2.0657 (6)2.019 (3)
2.0657 (6)
A (2)–Ft1.821 (4) 1.837 (3)
1.832 (3) 1.838 (3)
1.833 (4) 1.843 (3)
1.910 (3) 1.870 (3)
1.923 (3) 1.878 (3)
A (2)–Fb2.038 (3) 2.029 (3)
A–Fb–A155.63 (19)169.6 (3)145.09 (16)
a This work. b Ref. [25].
Table
Table 6. Experimental geometric parameters (Å) of the two crystallographically independent Ni+ cations, geometric parameters (Å) of the [XeF5]+ cations, and secondary Xe···F contacts in the crystal structures of XeF5Ni(AsF6)3 and literature data for XeF5Ni(SbF6)3.
Table 6. Experimental geometric parameters (Å) of the two crystallographically independent Ni+ cations, geometric parameters (Å) of the [XeF5]+ cations, and secondary Xe···F contacts in the crystal structures of XeF5Ni(AsF6)3 and literature data for XeF5Ni(SbF6)3.
XeF5Ni (AsF6)3 aXeF5Ni (SbF6)3 b
P21/n
150 K
Ni (1)–F2.000 (2)2.002 (1)
2.000 (2)2.002 (1)
1.994 (2)1.989 (1)
1.994 (2)1.989 (1)
2.006 (2)2.013 (1)
2.006 (2)2.013 (1)
Ni (2)–F1.999 (2)1.991 (1)
1.999 (2)1.991 (1)
2.006 (2)1.979 (1)
2.006 (2)1.979 (1)
2.010 (2)2.006 (1)
2.010 (2)2.006 (1)
Xe–Fax1.782 (2)1.800 (2)
Xe–Feq1.818 (2)1.825 (2)
1.819 (2)1.828 (2)
1.820 (2)1.826 (2)
1.822 (2)1.832 (2)
Xe···F2.903 (2)2.866 (2)
2.919 (3)2.928 (2)
2.931 (2)2.944 (2)
2.971 (3)2.898 (2)
a This work. b Ref. [35].
Table
Table 7. Experimental geometric parameters (Å) in the crystal structure of [Ni(XeF2)2](IrF6)2 and literature data for [Cu(XeF2)2](SbF6)2.
Table 7. Experimental geometric parameters (Å) in the crystal structure of [Ni(XeF2)2](IrF6)2 and literature data for [Cu(XeF2)2](SbF6)2.
[Ni (XeF2)2] (IrF6)2 a[Cu (XeF2)2] (SbF6)2 b
P21/c
150 K200 K
M–Fb (AF6)2.016 (6)2.090 (5)
2.016 (6)2.090 (5)
2.023 (7)2.123 (5)
2.023 (7)2.123 (5)
M–Fb (XeF2)1.938 (6)1.857 (5)
1.938 (6)1.857 (5)
Xe–Ft1.920 (7)1.906 (5)
Xe–Fb2.078 (6)2.102 (5)
A–Fb1.921 (7)1.891 (5)
1.934 (7)1.917 (5)
A–Ft1.843 (8)1.841 (6)
1.852 (8)1.843 (6)
1.858 (8)1.861 (6)
1.861 (8)1.870 (6)
a This work. b Ref. [54].
Table
Table 8. Summary of crystal data for the orthorhombic XeF5AsF6 and mixed anion [XeF5][As0.3Sb0.7F6) and [XeF5][As0.5Sb0.5F6) salts.
Table 8. Summary of crystal data for the orthorhombic XeF5AsF6 and mixed anion [XeF5][As0.3Sb0.7F6) and [XeF5][As0.5Sb0.5F6) salts.
CompoundCrystal SystemSpace GroupZa
/Å		b
/Å		c
/Å		T
/K
XeF5AsF6 aorthorhombicAma289.796 (2)13.272 (10)11.578 (2)100
[XeF5][As0.3Sb0.7F6] borthorhombicAma2(00γ)s0s810.031 (1)13.362 (1)11.808 (1)200
β-[XeF5][As0.5Sb0.5F6] borthorhombicAma2(00γ)s0s810.1196 (5)13.4517 (6)11.8999 (5)295
α-[XeF5][As0.5Sb0.5F6] borthorhombicPca21169.9738 (2)13.2492 (4)23.3701 (7)150
a Ref. [53]. b Ref. [37].
Table
Table 9. Effective ionic radii r(A5+) (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb) for coordination number six (Å), formula unit (molecular) volumes VFU (Å3) of LiAF6, CsAF6, and XeF5AF6, and average A–F bond lengths dav[A–F] (Å) in LiAF6 and XeF5AF6.
Table 9. Effective ionic radii r(A5+) (A = Nb, Ta, Ru, Rh, Os, Ir, Pt, Au, As, Sb) for coordination number six (Å), formula unit (molecular) volumes VFU (Å3) of LiAF6, CsAF6, and XeF5AF6, and average A–F bond lengths dav[A–F] (Å) in LiAF6 and XeF5AF6.
AAsRhAuPtIrRuOsSbNbTa
r(A5+) a0.460.550.570.570.570.5650.5750.600.640.64
LiAF6
VFU94.6 b98.64 c99.12 c99.61 c100.77 c100.5 c102.41 c105.3 d110.92 c111.26 c
dav[A–F]1.741.8551.8741.8871.8791.8511.8721.8771.8631.859
CsAF6
VFU e138.6141.2138.95143.4143.6141.7144.5149147.9149.3
VFU f 137.07 138.42138.97138.35139.97
XeF5AF6
TypeIIIIIIIIIIIIII
VFU g196.15 203.03196.35194.34193.26 199.42200
VFU h188.67181.18195.71190.15190.18188.62 195.11194.33195.85
dav[A–F]1.7191.8521.8931.8811.8761.852 1.8791.8881.892
a Ref. [56]. b Room temperature (RT); Ref. [58]. c 299 K; Ref. [57]. d RT; Ref. [59]. e RT; Ref. [60]. f 150 K; Ref. [61]. g 285 K for Ir salt (this work); others RT (Refs. [24,30,37,38,39,41]). h This work (150 K) except XeF5AsF6 (150 K) [37] and XeF5SbF6 (150 K) [25].
Table
Table 10. List of known xenon(VI) fluoridometallates including the determined crystal structures (letters in bold). Crystal structures reported in this work are highlighted in green.
Table 10. List of known xenon(VI) fluoridometallates including the determined crystal structures (letters in bold). Crystal structures reported in this work are highlighted in green.
Formula A5+
[Xe2F11][AF6]V aNb bTa cRu d Ir ePt fAu dU gP hAs iSb jBi k
[XeF5][AF6]V lNb mTa cRu nRhOs oIr ePt pAu fU r As sSb tBi u
[XeF5][A2F11]V lNbTa Sb t
a Refs. [21,27], b Ref. [62], c Ref. [63], d Refs. [26,39], e Refs. [23,39], f Ref. [39], g Ref. [76], h Ref. [22], i Refs. [22,29], j Refs. [19,28], k Ref. [77], l Ref. [78], m Refs. [30,62], n Ref. [38], o Ref. [39], p Ref. [24], r Ref. [79], s Refs. [20,22,41], t Refs. [19,25], u Ref. [80].
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Mazej, Z.; Goreshnik, E. Crystal Structures of Xenon(VI) Salts: XeF5Ni(AsF6)3, XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), and XeF5A2F11 (A = Nb, Ta). Molecules 2023, 28, 3370. https://doi.org/10.3390/molecules28083370

AMA Style

Mazej Z, Goreshnik E. Crystal Structures of Xenon(VI) Salts: XeF5Ni(AsF6)3, XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), and XeF5A2F11 (A = Nb, Ta). Molecules. 2023; 28(8):3370. https://doi.org/10.3390/molecules28083370

Chicago/Turabian Style

Mazej, Zoran, and Evgeny Goreshnik. 2023. "Crystal Structures of Xenon(VI) Salts: XeF5Ni(AsF6)3, XeF5AF6 (A = Nb, Ta, Ru, Rh, Ir, Pt, Au), and XeF5A2F11 (A = Nb, Ta)" Molecules 28, no. 8: 3370. https://doi.org/10.3390/molecules28083370

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