Elektrontransfer-katalysierte carbonyl-substitution: I. Synthese und spektroskopie von phosphantricarbonylmetall-komplexen der bidiazine

摘要: Abstract New phosphane tricarbonylmetal complexes fac-(R3P)(CO)3M(bdz) (R = n Bu, iPr; M  Mo, W) of the four isomeric bidiazine (bdz) chelate ligands 3,3′-bipyridazine, 2,2′-bipyrazine, 2,2′- and 4,4′-bipyrimidine were obtained via electron transfer catalyzed CO substitution tetracarbonylmetal precursors in good yields. The preparative procedure involves use sub-stoichiometric amounts (10–20 mol%) potassium metal to generate ESR-detectable anion radical intermediates, which then undergo selective one cis carbonyl group by way hyperconjugative charge from reduced ligand fragment. A catalytic cycle results because tricarbonyl can reduce tetracarbonyl precursors, seen electrochemistry. Ligand-centered ETC is fairly slow but proceeds at least order magnitude faster than daylight-induced process lead dissociation partially sensitive tricarbonyls. compounds are distinguished long-wavelength metal-to-ligand (MLCT) absorption bands resulting transitions between electron-rich low-lying π* orbitals bidiazines. Advantages disadvantages ligand-induced activation fragments discussed.