38496-28-5Relevant articles and documents
Electron-Transfer Catalysis. Radical Chain Mechanism for the Ligand Substitution of Metal Carbonyls
Hershberger, J.W.,Klingler, R.J.,Kochi, J.K.
, p. 3034 - 3043 (1982)
A novel chain process for the ligand substitution of metal complexes is revealed by bulk and transient electrochemical methods.The large turnover numbers that are obtained for the ligand substitution of the tris(acetonitrile) complexes of molybdenum and tungsten carbonyls with phosphines and isocyanides underscore the electrocatalytic phenomenon.The efficient chain process derives from the substitution lability of the cation radicals, which are formed by the one-electron oxidation of metal carbonyls and subsequently undergo rapid electron transfer, as in Scheme II.Th e driving force for ligand substitution is related to the relative stabilities of the cation radicals.Electron-transfer equilibria between these cation radicals can be evaluated from the standart reduction potentials E0 or the cyclic voltammetric peak potentials Ep.The initiation of the chain process is finely tuned to the value of E0 and Ep for the various metal carbonyls.The effectiveness of metal carbonyls as catalysts in the enhanced oxidation of nucleophiles such as triphenylphosphine is also described.
Intramolecular hydrogen-bonding, cation - π, and π-stacking interactions affecting cisltrans isomerization: Hexacarbonyltungsten derivatives of pyridyl-substituted arylphosphane ligands
Hirsivaara, Leeni,Haukka, Matti,Pursiainen, Jouni
, p. 2255 - 2262 (2007/10/03)
A series of triphenylphosphane- and diphenyl(2-pyridyl)phosphane-substituted tetracarbonyltungsten derivatives has been prepared. Attractive intramolecular interactions between the phosphane ligands have been studied in both the neutral and protonated complexes; π-stacking, hydrogen-bonding, and cation - π bonding interactions were identified and were found to have an influence on the cis/trans isomerism of the complexes. It was found that the cis/trans isomerism could be switched by protonation or deprotonation of the diphenyl(2-pyridyl)phosphane derivatives. The complexes have been characterized by 31P-, 1H-, and 13C NMR spectroscopy, X-ray crystallography, IR spectroscopy, and mass spectrometry.
