Crystal structure of bis-[(oxalato-κ2O1,O2)(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4N)chromium(III)] dichromate octa-hydrate from synchrotron X-ray data.
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 CrIIIion is coordinated by the four N atoms of the cyclam ligand and one bidentate oxalato ligand in acisarrangement, 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 thecis-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 Cr2O72-anion as acceptors, giving rise to a three-dimensional network.
Pohang Accelerator Laboratory, POSTECH, Pohang 37673, Republic of Korea.
Dohyun
D
Moon
Department of Chemistry, Andong National University, Andong 36729, Republic of Korea.
Jong-Ha
JH
Choi
bidentate oxalato ligand; chro­mium(III) complex; cis-V conformation; crystal structure; cyclam; dichromate anion; hydrogen bonding; synchrotron radiation