| Co-Investigator(Kenkyū-buntansha) |
KITA Masakazu Nagoya University Research Associate, 理学部, 助手 (20177827)
KOJIMA Masaaki Nagoya University Research Associate, 理学部, 助手 (20022725)
NONOYAMA Matsuo Nagoya University Research Associate, 理学部, 助手 (40022701)
KASHIWABARA Kazuo Nagoya University Associate Professor, 理学部, 助教授 (60004496)
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| Research Abstract |
A large number of metal complexes which comprise of soft ligands such as phosphines, arsines or their aminoalkyl derivatives and hard metals such as Co(III), the same group Rh(III) or Ir(III) were prepared, and their structures and physical and chemical properties were investigated. Most of the complexes are stable in the air, but some Co(III) complexes tend to liberate unidentate ligands trans to the phosphine in solution due to the trans effect of phosphine ligands. For example, ammine ligands are liberated by acids, arlthough ammines are very strong ligands in Co(III) complexes. X-ray analysis revealed lengthening of metal-ligand bonds trans to the phosphine, and a correlation. between M-P and M-N (M=Co, Rh) bond distances of the linear P-M-N group recognized. From electronic spectra the ligand field strength for 5B group donor atoms was obtained as P>As>N. Positive epi(P) values were obtained by spectral analysis of Co(III)-phosphine complexes, indicating that the Co-dpi orbitals are destabilized by coordination of phosphine ligands. The destabilization of Co-dpi orbitals by phosphine ligands are also indicated on redox potentials of the complexes. Oxidation potentials of phosphine pomplexes were observed more negative than those of the corresponding ammine complexes. Since the oxidation potential gives approximate energy of the HOMO of a complex, the result indicates that the Co-dpi orbitals (HOMO) in phosphine complexes are destabilized compared with those of the corresponding ammine complexes involving essentially no dpi-ppi interaction. A good linear relation between DELTAE=[oxidation potential - reduction potential] and nu(d-d) (the first d-d transition energy) was obtained for observed potentials of about 50 mixed phosphine complexes. The relation will be useful for elucidating the character of dpi (HOMO) and dsigma (LUMO) orbitals in metal complexes. Photo-reactivity of phosphine complexes was also studied.
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