Abstract
<p>The intrinsic potential of transition metal complexes to function as catalysts and to activate small molecules mainly originate from electronic unsaturation which can be induced by the coordination of sterically demanding ligands on the metal center. Chemistries of two electron deficient N-heterocyclic carbene (NHC)-platinum complexes were studied. The complex [Pt(IPr)(SnBu<sup>t</sup><sub>3</sub>)(H)] with an extremely bulky tritertbutylstannane group was found to be highly efficient in the catalysis of alkyne and alkene hydrostannation exhibiting high product selectivity. Studies on the unsaturated mixed phosphine carbene complex [Pt(IBu<sup>t</sup>)(PBu<sup>t</sup><sub>3</sub>)] showed its potential in small molecule activation and functionalization. Kinetic and computational studies on carboxylative cyclization of propargylamine with gold-NHC complexes were performed to gain further insights into the catalytic mechanism involving gold. The dinuclear gold(I) complex, [Au<sub>2</sub>(L)Cl<sub>2</sub>], (L = eightmethylene bridged bis(IPr)) studied shown to have a faster rate compared to the classic catalyst [Au(IPr)Cl]. Based on the detailed kinetic and computational studies on the [Au(IPr)Cl] system, a modified mechanism is proposed the rate and activation parameters for the conversion of the key intermediate to product were determined. Hyponitrite is an important intermediate in the oxidation of nitrous oxide to nitrite, where a potential metal oxo complex is involved in nitrous oxide binding. Reactivity of <em>cis</em>-[Pt(PPh<sub>3</sub>)<sub>2</sub>(η<sup>2</sup>-O<sub>2</sub>N<sub>2</sub>)] was investigated with carbon dioxide and mild acids. Experimental and computational studies on thermal and catalytic decomposition of <em>trans</em>-[R<sub>3</sub>(μ-ON=NO)SnR<sub>3</sub>] (R = cyclohexyl and phenyl) complexes were also performed where the rates and activation parameters for decomposition were determined.<br />
Furthermore, the results obtained for <em>cis</em> and <em>trans</em> forms of hyponitrites studied showed different trends of reactivity.</p>