Crystal structure of bis-[trans-(ethane-1,2-di-amine-κ(2) N,N')bis-(thio-cyanato-κN)chromium(III)] tetra-chlorido-zincate from synchrotron data.

The structure of the title compound, [Cr(NCS)2(C2H8N2)2]2[ZnCl4], has been determined from synchrotron data. In the asymmetric unit, there are four independent halves of the Cr(III) complex cations, each of which lies on an inversion centre, and one tetra-chlorido-zincate anion in a general position. The Cr(III) atoms are coordinated by the four N atoms of two ethane-1,2-di-amine (en) ligands in the equatorial plane and two N-bound NCS(-) anions in a trans arrangement, displaying a slightly distorted octa-hedral geometry with crystallographic inversion symmetry. The Cr-N(en) and Cr-N(NCS) bond lengths range from 2.0653 (10) to 2.0837 (10) Å and from 1.9811 (10) to 1.9890 (10) Å, respectively. The five-membered metalla-rings are in stable gauche conformations. The ZnCl4 anion has a distorted tetra-hedral geometry. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the en NH2 or CH2 groups as donors and chloride ligands of the anion and S atoms of NCS(-) ligands as acceptors.