||Reaction of Os(por)O2 [por = TTP, 5,10,15,20-tetra([italic]p-tolyl) porphyrinate(-II); OEP, 2,3,7,8,12,13,17,18-octaethylporphyrinate(-II)] with SOCl2 gave Os(por)Cl2 in good yields. Treatment of Os(por)CI2 with RLi (R = Ph, Me3SiCH2) gave air-stable diamagnetic dialkyl compounds Os(por)R2, which have been characterised by X-ray crystallography. The cyclic voltammogram of Os(TTP)Ph2 exhibits reversible Os(V)/(IV) couple at 0.32 V [italic]vs Cp2Fe+/0 (Cp2Fe = ferrocene). Oxidation of Os(TTP)Ph2 by AgBF4 afforded [Osv(TTP)Ph2][BF4]. Reaction of Ru(TBPP)O2 [TBPP = 5,10,15,20-tetrakis[italic]p-[italic]t- butylphenyl)porphyrinate(-II)] with Me3SiCl gave Ru(TBPP)Cl2. Treatment of Ru(TBPP)Cl2 with ArNH2 (Ar = [italic]p-XC6H4NH2, X = Me, H, Cl, I) afforded the first mono-imido-RuIV complexes Ru(TBPP)(NAr). Ru(TBPP)(NAr) exhibit reversible Ru(V)/Ru(IV) couple at [italic]ca 0.4 V [italic]vs Cp2Fe+/0. Treatment of Ru(TBPP)(NAr) with AgI or CeIV afforded [Ruv(TBPP)(NAr)][subperscript +]. The reductions of Ru(TBPP)(NAr) by PMe2Ph and PMe2 and PMe3 show saturation kinetics, suggesting binding of phosphine to the Ru(IV) complex prior to rate-limiting intramolecular imido transfer. The first-order rate constant ([italic]k[l) and phosphine binding constant ([italic]K) for the reduction of Ru(TBPP)(NC6H4Me-[italic]p) by PMe2Ph at 25.0 [degrees celsious] in toulene were determined to be 6.72 ± 0.19 x 10-4 s-1 and 38.4 ± 6.6 x 103, respectively. The activation enthalpy ([delta italic H double dagger]) and entropy ([delta italic S double dagger]) for the above reaction are 125 ± 1 kJ mol-1 and 113 ± 21 J K-1 mol-1, respectively. The Co-C stretching frequencies for Co(bpb)R(OH2), [Co(bpb)CH3]+ (bpb = 1,2-bis(2-pyridinecarboxamido)benzene) and Co(por)CH3 (por = porphyrinate(-II)) have been unambiguously determined by near-IR FT-Raman spectroscopy. Oxidation of Co(bpb)CH3(OH2) with Ce(IV) gave [CoIV(bpb)CH3]+ characterised by EPR spectroscopy. The Co-C stretching frequencies for CoIII(bpb)CH3(OH2) and [CoIV(bpb)CH3]+ have been determined to be 515 and 491 cm-1, respectively. Reactions of Li([italic]t-BuL-NS) (lithium bis(4-[italic]t-butylphenyl)-2- pyridylmethanthiolate(l-)) with MCl2 (M = Zn, Ni, Pt) afforded the respective M([italic]t-BuL-NS)2 complexes in good yields. Treatment of CuCl2 and PdCl2(PhCN)2 with Li([italic]t-BuL-NS) afforded dimeric compounds [Cu([italic]t-BuL-NS)Cl(OH2)]2 and [Pd([italic]t-BuL-NS)](μ-Cl)2, respectively. The interaction of Li([italic]t-BuL-NS) with [Ru(CO)2Cl2n and [Rh(cod)Cl]2 (cod =l,5-cyclooctadiene) gave respectively, [italic]cis-[Ru([italic] t-BuL-NS)2(CO)2] and the structurally characterised Rh([italic]t-BuL-NS)(cod). Ni, Ru and Cu complexes were found to catalyse oxidation of olefins by iodosylbenzene and [italic]tert-butylhydroperoxide. The Rh complex is an active catalyst for hydrogenation of olefin under ambient conditions.