Photochemistry of multiple metal coordination compounds with and without metal-metal bonding

The purpose of this work is twofold. First, the study of the photochemistry of metal-metal bonded compounds in the presence of stannylenes and the proposition of the mechanisms of the reactions may aid in possible uses of these compounds as radical scavengers, as catalysts for hydrogenation of olefins and also in desulfurization of coal and petroleum feedstocks, also as super reducing agents and bifunctional catalysts for Fischer-Tropsch process. Secondly, in the iron(III)-carboxylate photochemistry the determination of the factors influencing the photochemistry are crucial in solving the important questions of photoreactivity. This study is important as one of the possible ways in the treatment of the waste water and contaminated soil.;The photochemistry of metal-metal bonded carbonyl (Timers [CpW(CO) 3]2, [CpMo(CO)3]2, [CpFe(CO)2 ]2 and the mixed dimer [CpW(CO)3Fe(CO)2Cp] in the presence of cyclic bis(amino)stannylenes R2Si(N tBu)2Sn was investigated using visible light lambda=546 nm). The irradiation resulted in a homolytic cleavage of the metal-metal bond, and the production of the insertion products of the general formula [CpM(CO) xSn(R2Si(NtBu)2)M(CO) xCp], where R is either methyl or phenyl. Possible mechanisms of the formation of the insertion product include a 19-electron intermediate, photochemical disproportionation, or a bridged three-centered complex. Based on the experimental evidence, the involvement of the 19-electron radical is maintained and the photochemical disproportionation and the three-centered complex mechanisms were excluded. Quantum yield determinations were realized by UV/Vis spectroscopy. The quantum yields were dependent on the concentration of the cyclic stannylene and the intensity of the incident light. The insertion products were characterized by high-resolution mass spectrometry (HRMS), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and infra (IR) spectroscopy.;There are several factors influencing the photochemistry of iron(III)-carboxylate complexes. Our research focused on the influence of a variety of carboxylic acids (citric, 3-hydroxybutyric, pyruvic, amino acids) and also the influence of pH and constant ionic strength on the iron(III)-carboxylate photochemistry. The efficiency of the iron(III) carboxylate photochemistry was evaluated according to the quantum yield, which involves the reduction of Fe(III) to Fe(II). The study was performed by irradiation with UV-light, lambda=366 nm.