Theoretical Studies On The Transition Metal Carbonyl Compounds

The transition metal carbonyl chemistry is one of the important fields of organometallicchemistry. In the present thesis, two kinds of transition metal carbonyl compounds，namely,Co4(CO)n(n=10,9), Cp4V4(CO)4and Cp3V3(CO)9, were investigated at the BP86/DZP and PBE/DZPlevels of theory. The main results are listed as follows:(1) For the transition metal cobalt carbonyl compounds Co4(CO)n(n=10,9), both of the singletand triplet stable structures have been studied, and the results indicated that the central Co4networkfor most of the low-lying energy Co4(CO)n(n=10,9) structures is butterfy with five single Co–Cobonds, which is different with its Ir4(CO)n(n=12,11,10,9,8) analogues. In addition, varies carbonylcoordination modes have been found in the Co4(CO)n(n=10,9) complexes, including the terminalCO, μ-CO, μ3-CO and μ4-CO. However, Ir4(CO)n(n=12,11,10,9,8) compounds only have the sinpleterminal CO and bridging μ-CO groups. Meanwhile, the theoretical vibrational frequencies provideuseful information for experimentalist to synthesis this type of metal carbonyl compound.(2) For the transition metal vanadium carbonyl compounds Cp4V4(CO)4and Cp3V3(CO)9, theglobal minimum structure of Cp4V4(CO)4has four face-bridging μ3-CO groups around the V4tetrahedron, and one of them is a six-electron donor bridging CO group. Another unusual carbonylgroup, i.e., the four-electron donor η2-μ4-CO group bridging four vanadium atoms, has been foundin the next energetically low-lying isomers. None of the ten Cp4V4(CO)4structures has any terminalCO groups, which is disagreement with the experimental observation of terminal (CO) frequenciesin the infrared spectrum, and the experimental supposed structure was unstable. The globalminimum structure Cp3V3(CO)9has all terminal CO groups around the central equilateral V3triangle. In addition, the thermochemistry suggests that Cp3V3(CO)9is easily fragmentated into thestable compounds CpV(CO)4and Cp2V2(CO)5, which was the reason of Cp3V3(CO)9with low yieldfrom the Cp2V2(CO)5pyrolysis.