Opening the Third Century of Polyhalide Chemistry: Thermally Stable Complex with “Trapped” Dichlorine

Abstract

Unlike polyhalides of heavierh alogens, polychlorides still remaine xotic curiosities. Herein, we report preparation and investigation of complexes Cat 2 {[TeCl 6 ](Cl 2)} (cat = 1-methylpyridinium (1)a nd tetramethylammonium (2)) where dichlorine units are "trapped" by chlorotellurate(IV) anions via as ystemo fn on-covalent Cl•••Cl interactions. Complex 2 reveals ar ecord thermal stability (> 100 8C) for inclusion compounds with Cl 2 ,i ndications that such compoundsc an be used as solid Cl 2 source.

Oxochloroselenate(IV) with Incorporated {Cl2}: The Case of Strong Cl⋅⋅⋅Cl Halogen Bonding

“…As follows from the TGA data (Figure 5; see Supporting Information for details), 1 demonstrates remarkable thermal stability: the first step, corresponding to the loss of {Cl 2 } unit, is observed at > 150°C. This fact confirms that great stability found by us for TMA 2 {[MCl 6 ](Cl 2 )} [33,34] is not exceptional, and its appearance is not limited to the compounds of single structural type.…”

“…The shorter SeÀ μ 2 À Cl do have some covalent contribution (À G(r)/V(r) < 1), being rather strong (up to 6.8 kcal/mol [52] ), while the longer are purely non-covalent (À G(r)/V(r) > 1) with energies [52] not exceeding 2.4 kcal/mol. Third, despite our expectations based on XRD data, the Cl•••Cl halogen bonds (Figure 4) do not have any covalent contribution as well, despite relatively high energy (up to 3.5 kcal/mol, being almost twice greater than in other relevant complexes [33] ).…”

“…Most of these compounds contain polyiodides (these compounds are of interest due to their lower optical band gaps, [23,24] assuming their potential applicability in photovoltaics) or, less commonly, -bromides; meanwhile, complexes with "trapped" {Cl 2 } are yet very rare. The earlier single report describing Cat 2 {[MCl 6 ](Cl 2 )] (M=Sn IV and Pd IV[2] remained generally overlooked; very recently, we showed [33] that such complexes can be also prepared for Te IV[33] and Pb IV , [34] demonstrating unusually high thermal stability in the case of cat = TMA + .Despite it can be seen now that dichloro-chlorometalates can be prepared for, at least, four elements (Sn, [2,34] Te, [33] Pb [34] and Pd [2] ), their structural chemistry is yet not rich: all known structures are based on [M IV Cl 6 ] 2À building blocks which are…”

“…Despite it can be seen now that dichloro-chlorometalates can be prepared for, at least, four elements (Sn, [2,34] Te, [33] Pb [34] and Pd [2] ), their structural chemistry is yet not rich: all known structures are based on [M IV Cl 6 ] 2À building blocks which are…”

“…The Cl(1)•••Cl(2) distances (2.944 Å) are not only prominently less than the sum of r vdW for two Cl (3.50 Å [45,46] ), but also shorter than those in (1-MePy) 2 {[TeCl 6 ](Cl 2 )} (3.155 Å). [33] [a] Dr. A. N. Usoltsev This fact allows us expecting that this Cl•••Cl interaction must be significantly stronger than those in other dichlorine-chlorometalates. Unfortunately, the most straightforward approach (experimental charge density study via high resolution XRD; it was shown to be efficient for halogen bonding examination [47] ) is, most likely, inapplicable in the case of 1 due to disordering of TMA cations.…”