Crystal structure of bis-[ cis-(1,4,8,11-tetra-aza-cyclo-tetra-deca-ne-κ4N)bis(thio-cyanato-κ N)chrom-ium(III)] dichromate monohydrate from synchrotron X-ray diffraction data

Dohyun Moon; Masahiro Takase; Takashiro Akitsu; Jong-Ha Choi

doi:10.1107/S2056989016020120

Crystal structure of bis-[ cis-(1,4,8,11-tetra-aza-cyclo-tetra-deca-ne-κ⁴N)bis(thio-cyanato-κ N)chrom-ium(III)] dichromate monohydrate from synchrotron X-ray diffraction data

Acta Crystallogr E Crystallogr Commun. 2017 Jan 1;73(Pt 1):72-75. doi: 10.1107/S2056989016020120.

Authors

Dohyun Moon¹, Masahiro Takase², Takashiro Akitsu², Jong-Ha Choi³

Affiliations

¹ Pohang Accelerator Laboratory, POSTECH, Pohang 37673, Republic of Korea.
² Department of Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
³ Department of Chemistry, Andong National University, Andong 36729, Republic of Korea.

Abstract

The structure of the complex salt, cis-[Cr(NCS)₂(cyclam)]₂[Cr₂O₇]·H₂O (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-decane, C₁₀H₂₄N₄), has been determined from synchrotron data. The asymmetric unit comprises of one [Cr(NCS)₂(cyclam)]⁺ cation, one half of a Cr₂O₇^2- anion (completed by inversion symmetry) and one half of a water mol-ecule (completed by twofold rotation symmetry). The Cr^III ion is coordinated by the four cyclam N atoms and by two N atoms of cis-arranged thio-cyanate anions, displaying a distorted octa-hedral coordination sphere. The Cr-N(cyclam) bond lengths are in the range 2.080 (2) to 2.097 (2) Å while the average Cr-N(NCS) bond length is 1.985 (4) Å. The macrocyclic cyclam moiety adopts the cis-V conformation. The bridging O atom of the dichromate anion is disordered around an inversion centre, leading to a bending of the Cr-O-Cr bridging angle [157.7 (3)°]; the anion has a staggered conformation. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the cyclam N-H groups and water O-H groups as donor groups, and the O atoms of the Cr₂O₇^2- anion and water mol-ecules as acceptor groups, giving rise to a three-dimensional network.

Keywords: chromium(III) complex; cis-V conformation; crystal structure; cyclam; dichromate anion; hydrogen bonding; synchrotron radiation; thiocyanate ligand.