Crystal Structure, Raman Spectrum and Tl+ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB11H12]

Bareiß, Kevin U.; Enseling, David; Jüstel, Thomas; Schleid, Thomas

doi:10.3390/cryst12121840

Open AccessArticle

Crystal Structure, Raman Spectrum and Tl⁺ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB₁₁H₁₂]

by

Kevin U. Bareiß

¹,

David Enseling

²,

Thomas Jüstel

²

and

Thomas Schleid

^1,*

¹

Institute for Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany

²

Department of Chemical Engineering, FH Münster—University of Applied Sciences, Stegerwaldstraße 39, 48565 Steinfurt, Germany

^*

Author to whom correspondence should be addressed.

Crystals 2022, 12(12), 1840; https://doi.org/10.3390/cryst12121840

Submission received: 29 November 2022 / Revised: 8 December 2022 / Accepted: 9 December 2022 / Published: 16 December 2022

(This article belongs to the Special Issue Advances of Carborane Compounds)

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Abstract

:

Tl[CB₁₁H₁₂] was prepared with a reaction of Tl₂[CO₃] with the acid of the monocarba-closo-dodecaborate anion (H₃O)[CB₁₁H₁₂] in aqueous solution as prismatic colorless single crystals by isothermal evaporation from the clear brine. It crystallizes in a monoclinic primitive structure with the space group P2₁/c (a = 685.64(3) pm, b = 1978.21(9) pm, c = 1006.89(5) pm, β = 132.918(3)° for Z = 4), which can be derived from the halite-type arrangement if the closo-carbaborate cages are considered as spheres. Due to the different atoms in the [CB₁₁H₁₂]⁻ anion, Tl[CB₁₁H₁₂] features interesting C–H^δ+ ∙∙∙ ^δ−H–B interactions near to non-classical hydrogen bridges (“dihydrogen bonds”) and exhibits considerably different luminescence properties compared to regular closo-hydroborates, such as Tl₂[B₁₀H₁₀], Tl₂[B₁₂H₁₂] and Tl₃Cl[B₁₂H₁₂]. Tl[CB₁₁H₁₂] shows strong photoluminescence (PL) at 390 nm, while the excitation bands for this broad band are located at 245 and 280 nm. It is caused by an interconfigurational [Xe]4f¹⁴5d¹⁰6s² (³P₁) to [Xe]4f¹⁴5d¹⁰6s¹6p¹ (¹S₀) transition, which is also known as lone-pair luminescence. The quantum yield is rather low (<10 %), which is likely caused by the rather large Stokes shift. In addition, temperature-dependent emission spectra were recorded to determine the thermal quenching curve and the respective quenching temperature.

Keywords:

carborates; thallium(I) salts; monocarba-closo-hydroborates; single-crystal X-ray diffraction; Raman spectra; photoluminescence; stokes shift; thermal quenching

1. Introduction

Dodecahydro-monocarba-closo-dodecaborate monoanions [CB₁₁H₁₂]⁻ feature the same three-dimensional aromaticity like regular closo-dodecaborate dianions [B₁₂H₁₂]²⁻, which explains the striking thermodynamical stability of such species. Despite their high stability, which makes them easy to handle under atmospheric conditions, structural research on binary inorganic salts with [CB₁₁H₁₂]⁻ anions is still rather uncommon. Up to now only the crystal structures of the alkali-metal salts A[CB₁₁H₁₂] (A = Li–K and Cs) [1,2,3,4] have been reported, of which Li[CB₁₁H₁₂] and Na[CB₁₁H₁₂] were moved into the research focus due to their high cationic conductivity [1,2]. Their crystal structures are often based on simple structure types like the anti-fluorite-type for [B₁₂H₁₂]²⁻ containing salts A₂[B₁₂H₁₂] and the halite-type for those with [CB₁₁H₁₂]⁻ anions. Contrary to the closo-dodecaborates, monocarba-closo-dodecaborates do not crystallize within the cubic crystal system at room temperature, although they typically feature phase transitions into highly disordered cubic phases, as soon as the rotational barrier for the [CB₁₁H₁₂]⁻ anion is thermally abrogated [1,2,3,5].

In this study, we present the synthesis and characterization of the previously unknown thallium(I) salt Tl[CB₁₁H₁₂]. As the combination of cations with electronic lone pairs and closo-hydroborate anions provided salts with interesting photoluminescence properties, such as Tl₂[B₁₂H₁₂] [6,7], Tl₂[B₁₀H₁₀] [6], and Tl₃Cl[B₁₂H₁₂] [8], already it was a matter of particular interest to see, how the luminescence properties of Tl⁺ will change, when a carbon atom is substituted into the closo-borate cage within the [CB₁₁H₁₂]⁻ counter anion.

2. Materials and Methods

2.1. Synthesis

Thallium(I) dodecahydro-monocarba-closo-dodecaborate Tl[CB₁₁H₁₂] was prepared with a reaction of thallium(I) oxocarbonate Tl₂[CO₃] (Merck-Schuchardt, Hohenbrunn, Germany, 99 %) with the acid of the monocarba-closo-dodecaborate anion (H₃O)[CB₁₁H₁₂] in an aqueous solution. The free acid (H₃O)[CB₁₁H₁₂] itself was accessed by passing a concentrated aqueous solution of Cs[CB₁₁H₁₂] (Katchem, Prague, Czech Republic, 97 %) solution through a column filled with the highly acidic cation exchange resin Amberlite IR-120 (Merck, Darmstadt, Germany). Colorless prismatic single crystals of Tl[CB₁₁H₁₂] were obtained by isothermal evaporation from the clear solution of the initial reaction mixture.

2.2. Single-Crystal X-ray Diffraction

The selected single-crystal specimen of Tl[CB₁₁H₁₂] was prepared in a 0.1 mm glass capillary and measured on a κ-CCD four-circle single-crystal X-ray diffractometer (Bruker-Nonius, Delft, Netherlands) at room temperature. The diffractometer is equipped with a 1K CCD detector, a Mo-K_α X-ray tube and a graphite monochromator. Structure solution and refinement were carried out on basis of the SHELX-2013 program package [9].

2.3. Optical Spectroscopy

Raman-spectroscopic measurements were carried out on a XploRA Raman spectroscope (Horiba Jobin Yvon, Bensheim, Germany) equipped with a BX51 polarisation microscope (Olympus, Hamburg, Germany) and two solid-state lasers with wavelenghts of 532 nm (25 mW) and 638 nm (24 mW). For hardware calibration, the T_2g mode (521 cm⁻¹) of a silicon wafer was used.

The emission and excitation spectrum at room temperature as well as the temperature-dependent emission spectra of Tl[CB₁₁H₁₂] were collected using a fluorescence spectrometer FLS920 (Edinburgh Instruments, Livingston, UK) equipped with a 450 W Xenon discharge lamp (Osram, Munich, Germany). Additionally, a mirror optic for powder samples was used. The detection served a R2658P single-photon-counting photomultiplier tube (Hamamatsu, Herrsching am Ammersee, Germany). Temperature-resolved spectra were recorded by using a cryostat “MicrostatN” from Oxford Instruments (Abingdon, UK), wherein the powder sample was mounted.

For the determination of the reflection spectrum, the sample was placed into a Ba[SO₄] coated integrating sphere as part of an FLS920 (Edinburgh Instruments) spectrometer equipped with a 450 W Xenon lamp, and a cooled (–20 °C) single-photon counting photomultiplier (Hamamatsu R928). Ba[SO₄] was also used as a white reflectance standard. The excitation and emission band widths were 10.00 and 0.06 nm, respectively. The applied step width was 1 nm and the integration time was 0.5 s.

3. Results and Discussion

3.1. Crystal Structure

The thallium(I) dodecahydro-monocarba-closo-dodecaborate Tl[CB₁₁H₁₂] crystallizes in the monoclinic space group

P 2_{1} / c

with lattice parameters of a = 685.64(3) pm, b = 1978.21(9) pm, c = 1006.89(5) pm and

β

= 132.918(3)° for four formula units per unit cell. Further crystallographic data for the determination of the structure are given in Table 1 and the corresponding atom sites, thermal displacement parameters and selected inter-atomic distances can be found in Table 2, Table 3 and Table 4.

Due to the quite similar atomic form factors of carbon and boron [12], they cannot be distinguished in the Fourier syntheses unambigously, which is why the position of the single carbon atom of the [CB₁₁H₁₂]⁻ anion had to be determined by the structural differences between the different atom sites within the [CB₁₁H₁₂]⁻ cage as shown in Figure 1. So C1 shows the shortest intramolecular distances of 170 to 172 pm within the icosahedron, followed by C2 with values between 170 and 175 pm, whereas the distances between the boron atoms B2–B10 range from 175 to 180 pm, which is rather typical for B–B bond lengths in closo-dodecaborates. In addition to these differences in bond lengths, the hydrogen atoms H11 and H12 at the corresponding C1 and C2 atoms do not show any Tl–H interactions, hence predicting a reciprocally polarized C^δ−–H^δ+ bond in comparison with the B^δ+–H^δ− bonds. Therefore, it can be assumed that only one carbon site of the carbaborate cage is occupied at a time, due to a orientational disorder of the [CB₁₁H₁₂]⁻ anion within the crystal structure. This effect was observed for measurements both at room temperature as well as at −196 °C, suggesting a static instead of a dynamic disorder.

The differences in coordination of the individual hydrogen atoms of the [CB₁₁H₁₂]⁻ anion are shown in Figure 2. Clearly visible are the missing Tl–H contacts at the two possible carbon sites, but also the fact that three Tl⁺ cations are coordinated via edges or faces of the pseudo-icosahedral cages, but the remaining three on the top and at the right hand side of Figure 2 graft only terminally. The resulting distorted octahedral coordination of the [CB₁₁H₁₂]⁻ anion by Tl⁺ cations thus divides into three more distant terminal Tl⁺ cations with Tl–H distances from 286 to 307 pm with B–H–Tl angles of 138 to 152° and three closer Tl⁺ cations coordinated via edges (or faces) at distances from 272 to 298 pm, but much smaller angles of 109 to 116°. The three closer Tl⁺ cations always show a third contact to the [CB₁₁H₁₂]⁻ anion, which is emphasized as fragmented bond each due to the very long Tl∙∙∙H distances of 335–358 pm.

Regarding the coordination environment of the singular Tl⁺ cation in Tl[CB₁₁H₁₂] (Figure 3 and Figure 4), it also shows a distorted octahedral coordination of six [CB₁₁H₁₂]⁻ anions leading to a simple AB structure, if the [CB₁₁H₁₂]⁻ anions are treated as spheres, which is why the structure can be deduced from the NaCl-type arrangement. Figure 5 shows the resulting extended unit cell within the crystal structure of Tl[CB₁₁H₁₂], in which bilayers of [CB₁₁H₁₂]⁻ anions with intercalated Tl⁺ cations stacked along [010] are found. These bilayers feature surprisingly short H∙∙∙H contacts of 247 and 258 (2×) pm that all belong to C–H^δ+ ∙∙∙ ^δ−H–B contacts. These distances are significantly longer than non-classical dihydrogen bonds covering a typical range between 170 and 220 pm [13,14,15], however, but especially 248 pm as the shortest of them appear very close to twice of the van der Waals radii of hydrogen equaling 240 pm [16] and thus should yield a non-negligible electrostatic interaction. This also supports the proposed orientational disorder of the [CB₁₁H₁₂]⁻ anion, as only the positively partial charged hydrogen atoms bound to carbon show such short contacts.

The already known potassium monocarbaborate K[CB₁₁H₁₂] was reported to crystallize in the space group P2₁/c as well with a = 997.92(6) pm, b = 1967.82(6) pm, c = 998.41(6) pm and β = 93.267(2)° for eight formula units per unit cell on basis of ab-initio calculations and Rietveld refinements of X-ray powder diffraction data [2]. According to the shown unit cells in Figure 6, K[CB₁₁H₁₂] crystallizes isostructurally with Tl[CB₁₁H₁₂] as an ordered variant with an enlarged unit cell. Doubling the P2₁/c unit cell of Tl[CB₁₁H₁₂] along the a-axis leads to the one of K[CB₁₁H₁₂] in the P2₁/n setting and then can be transformed into the literature known P2₁/c cell of K[CB₁₁H₁₂] as shown in Figure 7. As we did not find any further reflections indicating a larger unit cell along the reciprocal a-axis in the reconstructed reciprocal diffraction images of Tl[CB₁₁H₁₂] (Figure 8), it can be stated that there is no ordering in our measured single-crystalline specimen of Tl[CB₁₁H₁₂]. The decision, whether rotational or orientational disorder is present, would be subject of further temperature-dependent investigations. The rotational disorder of the [CB₁₁H₁₂]⁻ anion around a pseudo-twofold axis, however, mimics roughly the structural arrangement of the neutral closo-dicarbadodecaborane o-[C₂B₁₀H₁₂] (1,2-[C₂B₁₀H₁₂]: monoclinic, Pc) [17].

3.2. Raman Spectrum

The single-crystal Raman spectrum of Tl[CB₁₁H₁₂] (Figure 9) appears almost identical to the known Raman spectrum of Cs[CB₁₁H₁₂] already described in the literature [3,18]. A sharp band with slight splitting can be seen at 3047 cm⁻¹, which originates from the C–H valence vibration [19]. This confirms the presence of carbon in the dodecaborate cage and also supports the assumption of alternating occupation of the C1 and C2 positions. Subsequently, in the region of the asymmetric breathing vibration of the carbaborate cage from 2600 to 2400 cm⁻¹, a splitting into several signals at 2583, 2563 and 2517 cm⁻¹ is observed. On the basis of density functional theory calculations, the interaction-free carbaborate anion [CB₁₁H₁₂]⁻ should even show seven different B–H stretching vibrations or vibration combinations according to its ideal C_5v symmetry [18]. In the solid state and coordinated to cations, both further splitting or reduction of the number of bands is possible. Next, from 1200 to 850 cm⁻¹, the B–H and C–H bending-vibration area can be observed, which is followed by the symmetric breathing mode of the carbaborate cage at 758 cm⁻¹ as most intense and sharp band in the whole spectrum. Subsequently, several B–B and C–B bending vibrations from 726 to 490 cm⁻¹ and finally the phalanx of lattice vibrations at 55 cm⁻¹ with a shoulder extending up to 140 cm⁻¹ are encountered.

3.3. Optical Spectra

The reflection spectrum of a Tl[CB₁₁H₁₂] sample (Figure 10) shows a high reflectance over most of the visible range, which is in line with the observation of a white body color of the microcrystalline powder. From the blue to violet range, the reflectance starts to decline, whereby over the whole UV range a broad unstructured absorption appears, which is assigned to absorption processes attributed to Tl⁺. A weaker shoulder at about 420 nm is visible, too, in which the origin may be caused by Urbach tailing (i.e., structural defect related absorption processes) [20].

The emission spectrum (Figure 11) upon excitation with UV radiation (280 nm) shows a broad-band peaking at 410 nm (23800 cm⁻¹) with a pretty large full width at half maximum of about 6200 cm⁻¹ and a tailing at the low energy edge, which extends to about 600 nm (16700 cm⁻¹).

It is assumed, that the photoluminescence process is caused by an interconfigurational [Xe]4f¹⁴5d¹⁰6s² (¹S₀) to [Xe]4f¹⁴5d¹⁰6s¹6p¹ (³P_J) transition (lone-pair luminescence) of Tl⁺. The detailed interpretation of the Tl⁺ luminescence was delivered by Seitz a long time ago [21]. He described the ground state of the free Tl⁺ ion as a non-degenerated singlet term ¹S₀ while the excited states are assigned as spin-orbit levels of the triplet term, viz. ³P₀, ³P₁, and ³P₂, as well as the singlet term ¹P₁ in sequence of increasing energy [21,22]. In view of the energy levels mentioned before, the strong excitation bands at 245 nm (40800 cm⁻¹) and 280 nm (35700 cm⁻¹) are assigned to the ¹S₀→³P₂ and ¹S₀→³P₁ transitions of Tl⁺, while the strong spin-orbit coupling in the case of the Tl⁺ cation lifts the spin-selection rule on these transitions [22]. The broad emission band and the large Stokes shift of about 11900 cm⁻¹ are reasonable for s² ions [23].

The fitting of the thermal quenching curve (Figure 12) between 100 and 500 K is done using the formula developed by Struck and Fonger [24,25,26]; see the equation below. We found that the activation energy E_a of the quenching process is solely 0.097 eV, and thus the quenching temperature T_1/2 is rather low, viz. at 230 K.

\frac{I (T)}{I_{0}} = {[1 + A e^{\frac{- E_{a}}{k_{b} T}}]}^{- 1}

Therefore, the photoluminescence is widely quenched at room temperature, and thus the quantum yield at 293 K is lower than 10 %. Such an observation is typically made for s²-cation activated luminescent materials with a large Stokes shift [23]. Due to the sole moderate signal-to-noise ratio of the emission spectra, the calculation of color coordinates or luminous efficacy values were not considered.

4. Conclusions

The previously unknown thallium(I) dodecahydro-monocarba-closo-dodecaborate Tl[CB₁₁H₁₂] was obtained as several millimeters large single crystals from aqueous solution. Its structure could be determined on basis of single-crystal X-ray diffraction data, which showed differences in terms of the carbon-versus-boron positions within the crystal structure as compared to the otherwise isostructural potassium salt K[CB₁₁H₁₂] [2]. Reconstructed reciprocal diffraction images were evaluated to prove the carbon-atom disorder in the crystal structure of Tl[CB₁₁H₁₂]. Therefore, Tl⁺ cations and [CB₁₁H₁₂]⁻ anions form a distorted halite-type structure with double layers of [CB₁₁H₁₂]⁻ cages and intercalated Tl⁺ cations. As for the closo-carbaborates, the usual hydrogen atoms bound to carbon atoms of the cage stay coordinatively inactive, thus the layers are stabilized by electrostatic C–H^δ+∙∙∙^δ−H–B interactions, which may be referred to as very weak non-classical hydrogen bonds (“dihydrogen bonds”).

In terms of optical properties, Tl[CB₁₁H₁₂] shows 6s² lone-pair luminescence with a maximum emission at 420 nm at 280 nm excitation. The quantum yield of less than 10 % at room temperature is rather low and can be explained by the low activation energy for thermal quenching, which is also reflected in temperature-dependent measurements showing maximum emission intensity in a range of 77 to 100 K. Compared to the luminescence properties of the already known related thallium(I) salts Tl₂[B₁₂H₁₂], Tl₂[B₁₀H₁₀] and Tl₃Cl[B₁₂H₁₂], the presented Tl[CB₁₁H₁₂] shows no red shifting of the photoluminescence like Tl₂[B₁₂H₁₂] or Tl₂[B₁₀H₁₀] (emissions at 522 and 510 nm) and has the highest full width at half maximum of 6200 cm⁻¹ compared to 4000 to 4700 cm⁻¹ of the closo-hydroborate salts. In the end, it cannot cope with the strong luminescence properties of Tl₃Cl[B₁₂H₁₂]; however, the mixed coordination sphere of chloride and hydridic hydrogen of the [B₁₂H₁₂]²⁻ anions seem to favour strong emission intensity and a high quantum yield (Figure 13) [6,8].

Author Contributions

Conceptualization, all authors; methodology, all authors; software, all authors; validation, all authors; formal analysis, all authors; investigation, all authors; resources, all authors; data curation, all authors; writing—original draft preparation, all authors; writing—review and editing, all authors; visualization, all authors; supervision, all authors; project administration, all authors.; funding acquisition, all authors. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Atom-numbering scheme of the [CB₁₁H₁₂]⁻ anion in Tl[CB₁₁H₁₂] with the atomic positions C1, C2, B1–B10, H1–H10, H11 and H12, where due to the orientational disorder only one of the two carbon sites is occupied at a time.

Figure 2. Heavily distorted octahedral coordination sphere of the anionic [CB₁₁H₁₂]⁻ cage by six Tl⁺ cations in the crystal structure of Tl[CB₁₁H₁₂].

Figure 3. Coordination sphere of the singular Tl⁺ cation in the crystal structure of Tl[CB₁₁H₁₂] by twelve hydrogen atoms (C.N. = 9 + 3) of six monocarbaborate anions [CB₁₁H₁₂]⁻.

Figure 4. Reduced coordination scheme of the Tl⁺ cation by hydrogen in the crystal structure of Tl[CB₁₁H₁₂] confined to the first coordination sphere of atoms with triangular planes to indicate the coordination of the monocarbaborate cages [CB₁₁H₁₂]⁻ via edges or faces.

Figure 5. Representation of two extended unit cells of Tl[CB₁₁H₁₂] along [101] with highlighted electrostatic C^δ−–H^δ+ ∙∙∙ ^δ−H–B^δ+ interactions.

Figure 6. Comparison of the ordered K[CB₁₁H₁₂] (left) and the disordered Tl[CB₁₁H₁₂] structure (right), showing that the determined positions of C1 and C2 are the same for both monoclinic arrangements after superimposition.

Figure 7. Symmetry relationship of the monoclinic unit cells of the literature-known K[CB₁₁H₁₂] [2] (red and blue) and the new Tl[CB₁₁H₁₂] (green).

Figure 8. Reconstructed reciprocal diffraction images of Tl[CB₁₁H₁₂], indicating no further h values that would lead to an ordering of the carbon-atom sites in the crystal structure of Tl[CB₁₁H₁₂].

Figure 9. Single-crystal Raman spectrum of Tl[CB₁₁H₁₂] recorded at an excitation wavelength of λ = 532 nm.

Figure 10. Reflection spectrum of a microcrystalline Tl[CB₁₁H₁₂] sample versus the white reflectance standard Ba[SO₄].

Figure 11. Room-temperature emission spectrum (black) under 280 nm excitation and the excitation spectrum (red) monitored at 420 nm of a white powder sample of Tl[CB₁₁H₁₂].

Figure 12. Temperature-dependent emission spectra (left) and temperature-dependent emission spectra integrals from 350 to 600 nm (right) of Tl[CB₁₁H₁₂] under 280 nm excitation between 100 and 500 K.

Figure 13. Comparison of the emission spectra of four different thallium(I) closo-hydroborates at an excitation wavelength of λ = 160 nm.

Table 1. Crystallographic data of Tl[CB₁₁H₁₂] and their determination.

empirical formula	Tl[CB₁₁H₁₂]
crystal system	monoclinic
space group	$P 2_{1} / c$ (no. 14)
lattice parameters
$a$ /pm	685.64(3)
$b$ /pm	1978.21(9)
$c$ /pm	1006.89(5)
$β$ /°	132.918(3)
number of formula units, $Z$	4
calculated density, $D_{x}$ /g ${cm}^{- 3}$	2.307
molar volume, $V_{m}$ / ${cm}^{3}$ ${mol}^{- 1}$	150.57
diffractometer	$κ$ -CCD (Bruker-Nonius)
radiation wavelength	Mo- $K_{α}$ : $λ = 71.07$ pm
diffraction limit, 2 $Θ_{m a x}$ /°	54.92
hkl range, $\pm h$ _max, $\pm k$ _max, $\pm l$ _max	8, 25, 12
$F$ (000)/ $e^{-}$	616
absorption coefficient, $μ$ / ${mm}^{- 1}$	16.07
extinction coefficient, ε	0.0114(5)
measured reflections	17,476
unique reflections	2283
$R_{i n t}$ , $R_{σ}$	0.064, 0.038
$R_{1},$ $w R_{2},$ GooF	0.034, 0.081, 1.028
Residual electron density(max., min. / $e^{-} 10^{- 6}$ ${pm}^{- 3}$ )	1.31, –1.14
CCDC number	2221677

Table 2. Fractional atomic coordinates and equivalent isotropic displacement parameters of Tl[CB₁₁H₁₂] (all atoms occupy the general Wyckoff site 4e).

Atom	$x$ / $a$	$y$ / $b$	$z$ / $c$	$U_{e q}$ $/ {pm}^{2}$
Tl	0.62389(6)	0.094958(15)	0.73978(4)	627(2)
C1\|B11 *	0.4456(14)	0.1820(3)	0.0867(9)	501(2)
H11	0.380	0.218	−0.021	601
C2\|B12 *	0.7656(15)	0.1829(4)	0.2906(10)	484(2)
H12	0.916	0.218	0.322	581
B1	0.5088(16)	0.2123(4)	0.2735(10)	493(2)
H1	0.489	0.266	0.293	592
B2	0.2288(14)	0.1606(4)	0.1112(10)	447(2)
H2	0.025	0.180	0.024	536
B3	0.3194(14)	0.1016(4)	0.0286(10)	459(2)
H3	0.175	0.083	−0.112	551
B4	0.6534(15)	0.1166(4)	0.1404(10)	468(2)
H4	0.727	0.108	0.073	562
B5	0.8532(15)	0.1012(4)	0.3737(10)	489(2)
H5	1.057	0.082	0.459	587
B6	0.7650(15)	0.1614(4)	0.4569(9)	489(2)
H6	0.912	0.181	0.596	587
B7	0.4234(14)	0.1461(3)	0.3429(10)	414(2)
H7	0.347	0.156	0.408	497
B8	0.3074(15)	0.0776(4)	0.1926(10)	443(2)
H8	0.156	0.042	0.160	665
B9	0.5716(13)	0.0500(3)	0.2102(9)	417(2)
H9	0.592	−0.003	0.190	500
B10	0.6406(15)	0.0775(4)	0.4084(10)	437(2)
H10	0.707	0.043	0.517	524

* These C-atom sites are both occupied by carbon and boron at an equivalent 1:1 molar ratio. Hydrogen atoms have been refined with a distance of 110 pm to their respective covalent binding partners (C and B) at 1.2 times of their equivalent isotropic displacement parameters using the SHELX command AFIX 153 [10,11].

Table 3. Selected intramolecular distances (d/pm) within the [CB₁₁H₁₂]⁻ anion in Tl[CB₁₁H₁₂].

C1\|B11	$-$ C2\|B12	170.1(10)	C2\|B12	$-$ C1\|B11	170.1(10)
	$-$ B3	171.1(9)		$-$ B5	172.8(11)
	$-$ B4	171.7(10)		$-$ B6	173.0(10)
	$-$ B2	171.7(9)		$-$ B4	173.7(10)
	$-$ B1	172.4(9)		$-$ B1	174.7(10)
	$-$ H11	110		$-$ H12	110
B1	$-$ C1\|B11	172.5(9)	B2	$-$ C1\|B11	171.7(9)
	$-$ C2\|B12	174.7(10)		$-$ B8	174.9(10)
	$-$ B6	175.9(11)		$-$ B7	175.1(10)
	$-$ B7	176.3(9)		$-$ B1	176.9(10)
	$-$ B2	176.9(10)		$-$ B3	177.3(10)
	$-$ H1	110		$-$ H2	110
B3	$-$ C1\|B11	171.0(9)	B4	$-$ C1\|B11	171.7(10)
	$-$ B9	175.2(10)		C2\|B12	173.8(10)
	$-$ B4	175.7(10)		$-$ B9	175.4(10)
	$-$ B2	177.3(10)		$-$ B3	175.7(10)
	$-$ B8	177.4(10)		$-$ B5	176.1(10)
	$-$ H3	110		$-$ H4	110
B5	$-$ C2\|B12	172.9(11)	B6	$-$ C2\|B12	173.0(10)
	$-$ B4	176.1(10)		$-$ B1	175.9(11)
	$-$ B9	177.1(10)		$-$ B10	177.6(10)
	$-$ B10	177.8(10)		$-$ B5	178.2(10)
	$-$ B6	178.2(10)		$-$ B7	179.8(10)
	$-$ H5	110		$-$ H6	110
B7	$-$ B2	175.1(10)	B8	$-$ B2	174.9(10)
	$-$ B1	176.3(10)		$-$ B7	176.6(10)
	$-$ B8	176.7(10)		$-$ B3	177.3(10)
	$-$ B10	177.6(10)		$-$ B9	178.0(9)
	$-$ B6	179.8(10)		$-$ B10	178.4(10)
	$-$ H7	110		$-$ H8	110
B9	$-$ B3	175.2(10)	B10	$-$ B6	177.5(10)
	$-$ B4	175.5(10)		$-$ B7	177.6(10)
	$-$ B5	177.1(10)		$-$ B5	177.8(10)
	$-$ B8	178.0(9)		$-$ B8	178.4(10)
	$-$ B10	179.3(9)		$-$ B9	179.3(9)
	$-$ H9	110		$-$ H10	110

Table 4. Distances (d/pm) between the Tl⁺ cations and coordinatively relevant hydrogen atoms of the [CB₁₁H₁₂]⁻ anions in Tl[CB₁₁H₁₂] up to 400 pm.

Tl	$-$ H9	272.5
	$-$ H7	275.0
	$-$ H2	280.7
	$-$ H10	285.4
	$-$ H5	286.3
	$-$ H4	293.3
	$-$ H8	293.4
	$-$ H3	298.1
	$-$ H1	306.5
	∙∙∙ H10	335.4
	∙∙∙ H8	335.9
	∙∙∙ H6	357.6

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Bareiß, K.U.; Enseling, D.; Jüstel, T.; Schleid, T. Crystal Structure, Raman Spectrum and Tl⁺ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB₁₁H₁₂]. Crystals 2022, 12, 1840. https://doi.org/10.3390/cryst12121840

AMA Style

Bareiß KU, Enseling D, Jüstel T, Schleid T. Crystal Structure, Raman Spectrum and Tl⁺ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB₁₁H₁₂]. Crystals. 2022; 12(12):1840. https://doi.org/10.3390/cryst12121840

Chicago/Turabian Style

Bareiß, Kevin U., David Enseling, Thomas Jüstel, and Thomas Schleid. 2022. "Crystal Structure, Raman Spectrum and Tl⁺ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB₁₁H₁₂]" Crystals 12, no. 12: 1840. https://doi.org/10.3390/cryst12121840

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