A molecular loop with interstitial channels in a chiral environment and study of formation of metal-metal bonds in dinickel, dipalladium and dititanium complexes
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This dissertation consists of two independent topics: (1) a molecular loop with interstitial channels in a chiral environment; (2) study of formation of metal-metal bonds in dinickel, dipalladium and dititanium complexes On the first topic, a study of the reaction products of the interaction of cis- Mo2(DAniF)2(CH3CN)4 2+ corner pieces with ortho-, meta- and para- isomers of enatiomerically pure ??O2CCH(CH3)C6H4CH(CH3)CO2 ?? dicarboxylate was performed. First, an enantiomerically pure molecular loop based on two dimolybdenum units and two para-dic arboxylate linkers was synthesized and structurally characterized. Similar reactions with isomeric ortho- and meta- dicarboxylate linkers, as well as with some nonchiral ligands, showed that the structure of the obtained products depends on the geometry of the ligand. Meta- dicarboxylate linker favors the formation of the chelated product and ortho- dicarboxylate linker produces the mixture of chelated molecules and loops. On the second topic, an investigation of the formation of metal-metal bonds was performed. Study of the one-electron bond obtained upon oxidation of Ni2 4+ and Pd2 4+ to Ni2 5+ and Pd2 5+, respectively, was made. The compounds synthesized were studied with various physical methods, such as X-ray crystallography, UV-visible spectroscopy and EPR spectroscopy. The nature of oxidized species as well as the dependence of metalmetal interactions on electron-donating abilities of bridging ligands was studied. It was shown that oxidation takes place on a metal center. The formation of one-electron bond in oxidized species is proposed. Finally formation of Ti2 6+ single bonded compounds by the reduction of two Ti4+ monomers to Ti2 6+ dimer was studied. The nature of the species obtained in solution and in solid state is discussed. The crystal structure shows the presence of two types of hpp ligands ?? chelating and bridging. NMR study of this compound in solution proposes the rearrangement of this structure to a paddlewheel.