BINUCLEAR COMPLEXES OF TRANSITION-METALS CONTAINING CARBONATE LIGANDS - PREPARATION, PROPERTIES, AND CRYSTAL-STRUCTURE OF (NH3)4CO(MU-NH2)(MU-OH)CO(CO3)2.5H2O

The reaction of a solution of μ-amido-μ-hydroxo-bis[tetraamminecobalt(III)] chloride and sodium bicarbonate at 40 °C resulted in the isolation of black needlelike crystals of μ-amido-μ-hydroxo-tetraamminebis(carbonato)cobalt(III) pentahydrate. The complex has been characterized unambiguously by means of a three-dimensional X-ray diffraction study. The complex crystallizes in the monoclinic space group P21/c [C2h5; No. 14] with a = 9.557 (2)Å, b = 15.848 (3)Å, c = 9.804 (2)Å, β = 90.31 (1)Å, V = 1484.8 (5)Å3,ρ(obsd) = 1.864 (13) g cm-3, andρ(calcd) = 1.919 g cm-3for Z = 4 and mol wt 429.11. Diffraction data were collected on a Syntex P2Xautomated four-circle diffractometer by using a coupled 8-28 scan and Mo Kα radiation. The structure was solved via direct methods and refined by difference Fourier and least-squares refinement techniques. The final discrepancy indices were RF= 4.4% and RvF= 3.8% for those 3435 total reflections in the range of 3.5° ≤ 2θ ≤ 50.0°. The cobalt(III) complex has the structure (NH3)4CO(μ-NH2)(μ-OH)CO(C03)2—i.e., both of the incoming carbonate ligands are chelated to the same cobalt atom. The cobalt(III) ions are each in an octahedral coordination environment, the Co(l)—Co(2) distance being 2.862 (1)Å. Important bond distances are Co-(ju-OH) = 1.932 (3) and 1.908 (2)Å, CO-(μ-NH2) = 1.916 (3) and 1.899 (3)Å, CO-NH3= 1.960 (3)-1.986 (3)Å, and Co-O(Co3) = 1.914 (2)—1.963 (2)Å. © 1979, American Chemical Society. All rights reserved.