Molybdenum compounds

The presence of multiply bonded dimetal units in materials offers opportunities for tuning properties of solids. Materials containing molybdenum-molybdenum quadruple bonds have recently begun being reported. This thesis reports the products of the reactions of dimethyl sulfide (DMS), acetonitrile (ACN) and acetate complexes, Mo2CI4(DMS)4, Mo2(ACN)10ABF4, and Mo2(0Ac)4
with 2,2';6,2"-terpyridine, 4'-phenyl 2,2';6,2"-terpyridine, 2,3,5,6-tetrakis (alpha-pyridyl) pyrazine and 1,3-bis(4-methylimino)isoindoline. Among these ligands, 2,3,5,6-tetrakis (alpha-pyridyl) pyrazine may lead to linear arrays of metal-metal bonds as well as other ordered structures. 1H-NMR, electronic absorption, and infrared data will be quoted to support any structural assignments.

The reduction of Mo2O4 (cysteine)2^2-, a model complex for molybdenum
redox enzymes, was studied using pr e parative and electrochemical
techniques. Molybdenum(IV) complexes prepared were Mo2O3(cysteine)^4- and Mo2O3 (cysteine)2^2-. Electrochemical reduction of Mo2O4 (cysteine)2^2- produced the monomeric molybdenum(IV)-cysteine complex. The
electrode reaction mechanism was found to be an ECE process and
involved two one-electron reduction steps. The intermediate in this
process was a Mo(V)/Mo(IV) mixed valence dimer, and its rate of
dissociation into Mo(V) and Mo(IV) monomers was 50 sec^-1 at pH 9.2 and 22°C. Mo2O4 (cysteine)2^2- was observed to react with free cysteine at pH 8-10. This reaction was first order in Mo2O4 (cysteine)2^2- and
first order in cysteine; the rate constant in pH 9.2 borate buffer was 10.9 ± 1.8 x 10^-3 M^-1 sec^-1 at 22°C. Cysteine was catalytically
regenerated in this reaction. The reaction was formulated as a cysteine-catalyzed
autooxidation-reduction of Mo2O4 (cysteine)2^2- yielding a
molybdenum(IV)-cystine dimer as the product.