title: Crystal structure of bis-[trans-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ(4) N)bis-(thio-cyanato-κN)chromium(III)] tetra-chlorido-zincate from synchrotron data.
abstract: The structure of the title compound, [Cr(NCS)2(cyclam)]2[ZnCl4] (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-decane, C10H24N4), has been determined from synchrotron data. The asymmetric unit contains two independent halves of the Cr(III) complex cations and half of a tetra-chlorido-zincate anion. In each complex cation, the Cr(III) atom is coordinated by the four N atoms of the cyclam ligand in the equatorial plane and by two N-bound NCS(-) anions in a trans axial arrangement, displaying a distorted octa-hedral geometry with crystallographic inversion symmetry. The mean Cr-N(cyclam) and Cr-N(NCS) bond lengths are 2.065 (4) and 1.995 (6) Å, respectively. The macrocyclic cyclam moieties adopt centrosymmetric trans-III configurations with six- and five-membered chelate rings in chair and gauche configurations, respectively. The [ZnCl4](2-) anion, which lies about a twofold rotation axis, has a slightly distorted tetra-hedral geometry. The crystal packing is stabilized by hydrogen-bonding inter-actions between the N-H groups of the cyclam ligands, the S atoms of the NCS(-) groups and the Cl(-) ligands of the anion.
authors.affiliation: Pohang Accelerator Laboratory, POSTECH, Pohang 790-784, Republic of Korea.
authors.forename: Dohyun
authors.initials: D
authors.lastname: Moon
authors.affiliation: Department of Chemistry, Andong National University, Andong 760-749, Republic of Korea.
authors.forename: Keon Sang
authors.initials: KS
authors.lastname: Ryoo
authors.affiliation: Department of Chemistry, Andong National University, Andong 760-749, Republic of Korea.
authors.forename: Jong-Ha
authors.initials: JH
authors.lastname: Choi
keywords: chromium(III) complex; crystal structure; cyclam; hydrogen bonding; synchrotron radiation; thio­cyanate ligand; trans-III configuration