Wechselwirkungen in Molekülkristallen, 111. Kristallzüchtung und Strukturbestimmung von Donator/Akzeptor‐Komplexen aus 1,2,4,5‐Tetrakis(alkylthio)benzolen und Brom oder Iod

Abstract

Interactions in Crystals, 111Part 110: Ref.[1]. . — Crystallization and Structure Determination of Donor/Acceptor Complexes between 1,2,4,5‐Tetrakis(alkylthio)benzene Derivatives and Bromine or Iodine Based on preceding cyclovoltammetric and UV/Vis measurements, red crystals of the donor/acceptor complex {1,2,4,5‐tetrakis(ethylthio)benzene…(Br2)2} are grown by using Br2 gasphase diffusion into a CCl4 solution of 1,2,4,5‐tetrakis(ethylthio)benzene. In addition, the corresponding iodine complex {1,2,4,5‐tetrakis(isopropylthio)benzene ⃛(I2)3} is crystallized. The structure determinations prove for the I2 adduct an interesting packing motif, in which two crystallographically independent I2 acceptors bridge each four sulfur donors. The Br2 adduct shows a three‐dimensional network with subunits >S ⃛BrBr ⃛S<, in which the BrBr bond is surprisingly elongated by 13 pm (!) relative to the gasphase electron diffraction value for bromine. — The structure discussion is based on iodine acceptor complexes listed in the Cambridge Structural Database and reveals angular‐dependent iodine coordination vectors to sulfur as well as a correlation between II bond lengths and contact distances S ⃛I. Density functional calculations for the model system (H3C)2S ⃛BrBr ⃛S(CH3)2 with the experimentally determined structural parameters suggest that a charge of ‐0.25 is transferred to the BrBr acceptor molecule, which allows to rationalize its 13‐pm elongation on complexation to {1,2,4,5‐tetrakis(ethylthio)benzene ⃛(Br2)2}.