Trimethylammonium Sn(IV) and Pb(IV) Chlorometalate Complexes with Incorporated Dichlorine

: Supramoleculardichloro-chlorostannate(IV)and-plumbate(IV)complexes(Me 3 NH) 2 {[MCl 6 ]Cl 2 } (M = Sn ( 1 ), Pb ( 2 )) feature dichlorine units incorporated into a halometalate framework. Both compounds were characterized by X-ray diffractometry and Raman spectroscopy.


Materials and Methods
All reagents were used as purchased.Caution: All experiments with Cl 2 require obligatory safety precautions-sufficient exhaust ventilation (fume hood must be used), and obligatory eye (goggles) and skin (gloves) protection.Soluble Pb(II) salts are toxic.

Preparation of 2
111 mg (0.22 mmol) of PbO and 96 mg (1 mmol) of Me 3 NHCl were dissolved in 5 mL of concentrated HCl at 60 • C. Then gaseous Cl 2 was bubbled through the solution at the same temperature for 10 min.After that, the flask was closed and slowly cooled to room temperature, resulting in formation of transparent crystals of 1 within several hours.The yield was 71%.The element analysis for C 6 H 20 N 2 PbCl 6 is (see Discussion): calculated, %: C, 13.38; H, 3.74; N, 5.20; found C, 13.33; H, 3.77; N, 5.27.).The only one major crystal domain of 1 and both major domains of 2 were used for the intensity integration via SAINT.Scaling and absorption corrections of the experimental intensities were performed empirically in the medium absorber (3 odd/6 even orders for spherical harmonics, spherical correction µ•r = 0.2) and strong absorber models (7 odd/8 even OSH, µ•r = 1.2) using SADABS and TWINABS programs for 1 and 2, respectively.The structures were solved by SHELXT [45] and refined using the full-matrix least-squares by SHELXL [46] assisted with Olex2 GUI [47].
Non-H atoms for all structures were located from the electron density map and refined in the anisotropic approximation.H atoms were located from the electron difference maps and refined in a riding model with the constrained U iso .Site occupation factors of Cl atoms of guest Cl 2 molecules, located around special positions (Wyckoff positions 6a, 32 point symmetry) were fixed as 1/3 (i.e., the guest positions are singly occupied by Cl 2 molecules).The crystallographic characteristics, experimental data, and structure refinement indicators are shown in Table 1.The crystallographic data and experimental details were deposited in the Cambridge Crystallographic Data Centre under the deposition codes CCDC 2154812 (1) and 2167558 (2) and can be obtained at https://www.ccdc.cam.ac.uk/structures (accessed on 10 November 2022).

Raman Spectroscopy
Raman spectra were collected using a LabRAM HR Evolution (Horiba) spectrometer with the excitation by the 633 nm line of the He-Ne laser.The spectra at room temperatures were obtained in the backscattering geometry with a Raman microscope.The laser beam was focused to a diameter of 2 µm using a LMPlan FL 50×/0.50Olympus objective.The spectral resolution was 0.7 cm −1 .The laser power on the sample surface was about 0.03 mW.

Results and Discussion
Both complexes were prepared via bubbling of Cl 2 through HCl solution of corresponding chlorometalate(IV) (in the case of Pb, it is generated in situ during dissolution of oxide in HCl) with trimethylammonium chloride, resulting in crystals suitable for XRD.Both compounds are isostructural.There are mononuclear [MCl 6 ] 2− anions (M-Cl = 2.425-2.427and 2.504-2.507Å for Sn and Pb, respectively).Similar to (Me 4 N) 2 {[MCl 6 ](Cl 2 )} (M = Sn, Pb) described earlier [43], the dichlorine units (the Cl-Cl bond lengths are 1.994 in 1 and 1.996 in 2, respectively) are disordered over three positions with equal occupancies so the system of Cl•••Cl non-covalent interactions (Figure 1       Both complexes demonstrate poor stability while kept outside the Cl 2 -containing mother liquor, and lose Cl 2 , transforming into (Me 3 NH) 2 [MCl 6 ], as follows from element analysis of residues (see Experimental part).The PXRD data (Figures 3 and 4) confirm that after 1 h the samples of 1 and 2 contain up to 33% of "dichlorine-free" salts (for comparison of the structural data, we used the XRD information for (Me 3 NH) 2 [SnCl 6 ] which was described earlier [48]; the (Me 3 NH) 2 [PbCl 6 ] salt was found to be isostructural).Hirshfeld surface analysis of the structures of 1 and 2 is given in Supplementary materials.The stability of compounds did not allow performance of TGA experiments; however, we succeeded in recording of Raman spectra (Figures 5 and 6).The bands corresponding to the {Cl2} unit vibrations (518-531 and 508-520 cm −1 , respectively) are shifted to the lower wavelengths; this is a common feature for the compound of this family [43] (for gaseous Cl2, the bands were detected at 539, 547 and 554 cm −1 [52]).There are also It is worth mentioning that supramolecular complexes with halide•••dichlorine noncovalent interactions are yet very rare.Apart from polychlorides extensively studied in last decade by Riedel et al. [49][50][51], the number of such examples is very limited.
Hirshfeld surface analysis of the structures of 1 and 2 is given in Supplementary Materials.The stability of compounds did not allow performance of TGA experiments; however, we succeeded in recording of Raman spectra (Figures 5 and 6).The bands corresponding to the {Cl 2 } unit vibrations (518-531 and 508-520 cm −1 , respectively) are shifted to the lower wavelengths; this is a common feature for the compound of this family [43] (for gaseous Cl 2 , the bands were detected at 539, 547 and 554 cm −1 [52]).There are also bands at 312, 242, 165 cm −1 for 1 and 278, 218, 143 cm −1 for 2 corresponding to ν 1 , ν 2 (stretching) and ν 5 (deformation) vibrations in {MCl 6 } octahedral units [53].Hirshfeld surface analysis of the structures of 1 and 2 is given in Supplementary materials.The stability of compounds did not allow performance of TGA experiments; however, we succeeded in recording of Raman spectra (Figures 5 and 6).The bands corresponding to the {Cl2} unit vibrations (518-531 and 508-520 cm −1 , respectively) are shifted to the lower wavelengths; this is a common feature for the compound of this family [43] (for gaseous Cl2, the bands were detected at 539, 547 and 554 cm −1 [52]).There are also bands at 312, 242, 165 cm −1 for 1 and 278, 218, 143 cm −1 for 2 corresponding to ν1, ν2 (stretching) and ν5 (deformation) vibrations in {MCl6} octahedral units [53].

Conclusions
To conclude, the series of Sn and Pb dichlorine-contanining supramolecular compounds featuring Type I Cl•••Cl interactions (according to the classification proposed by Metrangolo et al. [54]) was expanded by adding two new complexes.It is noteworthy that,

Conclusions
To conclude, the series of Sn and Pb dichlorine-contanining supramolecular compounds featuring Type I Cl•••Cl interactions (according to the classification proposed by Metrangolo et al. [54]) was expanded by adding two new complexes.It is noteworthy that, unlike tetramethylammonium-containing relatives, 1 and 2 demonstrate poor stability.This observation confirms the crucial role of multiple cation•••anion hydrogen bonds in overall stabilization of the compounds of this type.While all complexes of this family reported contained dichlorine units, we, as stated previously [43], cannot exclude the existence of compounds where other, more sophisticated polychlorine fragments would be stabilized (the overall progress in research of polychlorides [49,50,55] encourages this hypothesis).The corresponding experiments are underway in our group.

2. 1 .
Preparation of 1 50 mg (0.22 mmol) of SnCl 2 •2H 2 O and 42 mg (0.44 mmol) of Me 3 NHCl were dissolved in 4 mL of concentrated HCl at 60 • C. Then gaseous Cl 2 was bubbled through the solution at the same temperature for 10 min.After that, the flask was closed and slowly cooled to room temperature, resulting in the formation of transparent crystals of 1 within several hours.The yield was 69%.The element analysis for C 6 H 20 N 2 SnCl 6 is (see Discussion): calculated, %: C, 16.00; H, 4.48; N, 6.23; found C, 15.94; H, 4.52; N, 6.29.

Figure 2 .
Figure 2. Crystal packing in the structures of 1 and 2. C and H: grey, N: deep blue, metal: black, Cl: light green.

Figure 2 .
Figure 2. Crystal packing in the structures of 1 and 2. C and H: grey, N: deep blue, metal: black, Cl: light green.

Figure 2 .
Figure 2. Crystal packing in the structures of 1 and 2. C and H: grey, N: deep blue, metal: black, Cl: light green.

Table 1 .
Details of the XRD experiments for 1 and 2.