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 CrIII 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 Cr2O72- anion as acceptors, giving rise to a three-dimensional network.
Highlights
The asymmetric unit of the title compound, [Cr(C2O4)(C10H24N4)]2[Cr2O7]8H2O (C10H24N4 = 1,4,8,11-tetraazacyclotetradecane, 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 disordered over two positions, and four water molecules
The terminal O atoms of the dichromate anion are disordered over two positions with a refined occupancy ratio 0.586 (6):0.414 (6)
The Cr—N(cyclam) bond lengths are in the range 2.069 (2)–2.086 (2) Å, while the average Cr—
Summary
Chromium (Cr) is considered a trace element essential for the proper functioning of living organisms and is a highly toxic material (Yusof & Malek, 2009). It has been found that cyclam derivatives and their metal complexes exhibit anti-HIV activity (Ronconi & Sadler, 2007; De Clercq, 2010; Ross et al, 2012). Knowledge of the conformation and hydrogen-bonding interactions in CrIII–CrVI complex systems containing the cyclam ligand has become important in the development of new anti-HIV drugs (De Clercq, 2010). The use of such complexes for the more effective removal of toxic metals is important (Guzel et al, 2016).
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