Crystal structure of bis-[(oxalato-?²O¹,O²)(1,4,8,11-tetra-aza-cyclo-tetra-decane-?⁴N)chromium(III)] dichromate octa-hydrate from synchrotron X-ray data.

ABSTRACT: The asymmetric unit of the title compound, [Cr(C₂O₄)(C₁₀H₂₄N₄)]₂[Cr₂O₇]·8H₂O (C₁₀H₂₄N₄ = 1,4,8,11-tetra-aza-cyclo-tetra-decane, cyclam; C₂O₄ = oxalate, ox) contains one [Cr(ox)(cyclam)]⁺ cation, one half of a dichromate anion that lies about an inversion centre so that the bridging O atom is equally disordered over two positions, and four water mol-ecules. The terminal O atoms of the dichromate anion are also disordered over two positions with a refined occupancy ratio 0.586?(6):0.414?(6). The Cr^III ion is coordinated by the four N atoms of the cyclam ligand and one bidentate oxalato ligand in a cis arrangement, resulting in a distorted octa-hedral geometry. The Cr-N(cyclam) bond lengths are in the range 2.069?(2)-2.086?(2)?Å, while the average Cr-O(ox) bond length is 1.936?Å. The macrocyclic cyclam moiety adopts the cis-V conformation. The dichromate 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 donors, and the O atoms of oxalate ligand, water mol-ecules and the Cr₂O₇^2- anion as acceptors, giving rise to a three-dimensional network.

SUBMITTER: Moon D 

PROVIDER: S-EPMC5347064 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature