Collect. Czech. Chem. Commun. 1982, 47, 1721-1732

Electrochemical behaviour of molybdenum-nitrosyl complexes of the type Mo(NO)2Cl2L2 and Mo(NO)Cl3L2

Jiří Mašeka, Jan Fiedlera, Jiří Klímaa, Karl Seyferthb and Rudolph Taubeb

a The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 121 38 Prague 2
b Technical University „Carl Schorlemmer", Leuna-Merseburg, 42 Merseburg, G.D.R.


Electrochemical behaviour of 22 molybdenum-nitrosyl complexes of the title types serving as catalyst precursors of olefin metathesis reactions was investigated and the odd-electron localization in the 1-electron reduction products was determined by ESR spectroscopy. It was found that the mononitrosyl complexes containing the fragment {Mo(NO)}4 are reduced in a potential region more positive and distinctly separated from that of the dinitrosyl complexes containing the fragment {Mo(NO)2}6. In the reduction of the former complexes the electrons are accepted into a MO having prevailingly metal d-character while with the latter class of complexes the electrons accepted in the reduction are accommodated in a π-NO based MO. The comparison of the electrochemical results with the catalytic activity of the corresponding systems shows that the ability of the precursor complexes to form the catalytically active species depends on their substitution lability rather than on their redox properties.