Design, Syntheses, Characterization and Substrate Transformation by Model Oxo-Molybdenum Complexes of Dithione

A series of monooxo molybdenum(IV) dithione complexes were synthesized by reacting N,N dimethyl piperazine 2,3 dithione (Me2Pipdt) or N,N diisopropyl piperazine 2,3 dithione (i-Pr2Pipdt), with MoVCl5. These complexes reduce nitrate, DMSO and TMAO, which were probed by spectroscopy. The oxidized complex can be reduced to the parent Mo(IV) center by tertiary phosphine. The phosphine oxide has been detected by 31P NMR spectroscopy. The phosphine also coordinates the Mo(IV) center, thus acts as an inhibitor. In the presence of pyridine, monooxo Mo(IV) complex converts to a desoxo Mo cluster with four Mo metal centers. Structure of this cluster reveals long metal-metal interaction and weak coordination by the BF4 anion. Its synthesis and characterization will be discussed in the third Chapter. Fourth Chapter describe a series of cationic nickel complexes synthesized using the same ligands and identified that, [(i-PrPipdt)2Ni][BF4]2 complex, converted to [(i-PrPipdt)3Ni][BF4]2 in methanol in air. The structure shows an interesting packing feature. The redox potentials of the complex does not depend on the counter ion. The synthesis, structural and spectroscopic characterization of the (Me2Pipdt)Mo(CO)4 complex is discussed in the final chapter. The molecular structure underscores the flexibility of the NC(S)C(S)N fragment in both the free ligand and the metal complex. The complex shows solvatochromic properties