X-ray Crystal Structures and Two-dimensional π···π Stacking Interaction of Cr III (X 4 SQ) 3 ·4C 6 H 6 (X=Cl and Br)

Abstract

Tris(tetrahalogeno- o -semiquinonate) chromium (III) complexes, Cr III (Cl 4 SQ) 3 ·4C 6 H 6 ( 1 ) and Cr III (Br 4 SQ) 3 ·4C 6 H 6 ( 2 ), crystallize in an isostructural form; tetragonal, P 4 1 2 1 2 with a = 13.452(2) Å 3 , c = 24.78(2) Å, V = 4484(3) Å 3 and a = 13.7465(7) Å, c = 25.680(1)Å, V = 4852.6(4) Å 3 for 1 and 2 , respectively. The inner coordination environments of the complex molecules are similar to that of previously reported crystal, Cr III (Cl 4 SQ) 3 ·CS 2 ·1/2C 6 H 6 , while both complexes show strong π···;π interaction between the three SQ ligands and the four solvate benzene molecules, resulting the formation of two-dimensional π···π stacking array. The effect of π·π interactions was evaluated by thermogravimetric and differential scanning calorimetric analysis where the weigh loss corresponding to the four benzene molecules was observed up to 500 K indicative of the interactions between the ligands and solvated benzene molecules.