(+ac,-ac)-trans-Bis(hinokitiolato)copper(II) and its chloroform disolvate.

The complex trans-bis(hinokitiolato)copper(II) [systematic name: trans-bis(3-isopropyl-7-oxocyclohepta-1,3,5-trienolato)copper(II); abbreviated name: trans-Cu(hino)2], [Cu(C10H11O2)2], is a biologically active compound. Three polymorphs of this square-planar monomer, all with (+sp,-sp) isopropyl substituents, have been reported previously. A fourth polymorph containing (+ac,-ac) isopropyl groups and its chloroform disolvate, [Cu(C10H11O2)2].2CHCl3, both exhibiting nonmerohedral twinning and with all Cu atoms on centers of crystallographic inversion symmetry, are reported here. One of the differences between all of these polymorphs is the relative conformation of the isopropyl groups with respect to the plane of the molecule. Stacking and Cu...olefin pi distances ranging from 3.214 (4) to 3.311 (2) A are observed, and the chloroform solvent molecules participate in bifurcated C-H...O hydrogen bonds [H...O = 2.26-2.40 A, C...O = 3.123 (5)-3.214 (5) A, C-H...O = 127-151 degrees and O...H...O = 74 degrees].