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

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.

SUBMITTER: Moon D 

PROVIDER: S-EPMC5209776 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature