Masato Kamata

Mo(IV) Complexes of cysteine-containing peptides and their interaction with 4Fe ferredoxin model complexes

Abstract Mo(Ac-cys-OH)4, Mo(S-tBu)2 (Z-Ala-cys-OMe)2 (Z = carbobenzoxy), and Mo(Z-cys-Ala-Ala-cys-OMe)2 were prepared from Mo(S-tBu)4 and the corresponding peptides using a ligand exchange method. The Mo(IV) complexes were characterized by 1H NMR, visible, and CD spectra. Reaction of these complexes with 4Fe ferredoxin model complexes, [Fe4S4(SR)4]2−, was examined by CD spectroscopy to reveal ligand exchange between these complexes. Formation of a MoFe mixed cluster was implied by the Cd results.

Molybdo-Iron Mixed Cluster as a Fe-Mo Cofactor Model

Recently, an iron-molybdenum cofactor (Fe-Moco) of low molecu lar weight (less than 5000 Dalton) was isolated from the ironmolybdenum protein of A. vinelandi and C. pasteurianum nitrogenases.1,2 The molybdenum environment in the Fe-Moco was studied by EXAFS3 (extended X-ray absorption fine structure) spectroscopy, which implicated molybdenum in a Mo-Fe-S cluster unit, possibly 1 or 2.4 Apparently prompted by these findings, bi-cluster compounds, 3 5 Open image in new window and 46 , have been prepared, whose structures were established by X-ray analysis. We were able to synthesize a mono-cluster compound whose framework is believed to be similar to 1. This paper describes Open image in new window it’s characterization and catalytic activity for acetylene half-reduction.