THE X-RAY STRUCTURE-ANALYSIS OF BIS-2,2',N,N'-BIPYRIDYL KETONE COBALT(III) NITRATE DIHYDRATE

An X-ray structural analysis of bis-2,2',N,N'-bipyridyl ketone cobalt(III) nitrate dihydrate, CoC22H20N4O4+. NO3-.2H2O, M(r)=559.38 g/mol, P1BAR, a=8.862(2), b=16.195(3), c=8.772(2) angstrom, alpha=103.54(2), beta=95.74(3), gamma=105.07-degrees, V=1164.4(4) angstrom3, Z=2, D(x)=1.595 g/cm3, Mo Kalpha radiation (lambda=0.71073 angstrom), mu=7.8 cm 1 and R = 0.079, revealed a Co(III) cation in a slightly distorted octahedral environment. The structure reveals that the ligand di-2-pyridyl ketone (dpk) has undergone a hydration reaction across the ketone double bond and one of the hydrate oxygen atoms coordinated to the metal forming a tridentate chelate. This new Co(dpk-hydrate)2+ complex displays the least distorted geometry yet reported for either 1:1 or 1:2 (metal:ligand) complexes. A geometry optimization using the INDO model Hamiltonian as implemented in the program ZINDO was performed on the title complex with the Co3+ modeled as a singlet. The result of the computation corroborates the geometry of the title complex as that expected for Co3+.