Abstract:
Recent interest in the insertion reactions of carbon monoxide and isocyanides into metal alkyl and aryl bonds have been stimulated by the industrial uses of such processes. This thesis describes the single crystal structures of a precursor aryl complex of Ru(II) and three intermediate complexes in this insertion process.
The crystal structure of RuRCl(CO) (PPh3)2 exhibits a ruthenium-carbon bond and is five-coordinate with α-hydrogens of the phosphines in the sixth position. The model is disordered with respect of the chlorine and carbonyl ligands.
The structure of the dihapto-iminoacyl complex Ru[C(p-tol)N(p-tol)]Cl(CO) (PPh3), made by reaction of isocyanide with the above is again disordered. The dihaptoiminoacyl ligand is approximately symmetrically bound through both carbon and nitrogen atoms forming a three centre bond. The angle at the bound carbon atom varies significantly from the ideal sp2 value and an explanation is proposed.
Carbonylaton of methyl and tolyl complexes of Ru(II) gives the acyl complexes Ru[C(O)R]Cl(CO) (PPh3)2 (R = Me, p-tol). Crystal structure analyses of these were undertaken. Both were dihapto complexes with both carbon and oxygen atoms bound. The angles at the bound carbon were close to the sp2 ideal.
Much confusion surrounds the wide-ranging complexing forms of Mo(VI). Preparation of an ammonium molybdate complex of the sugar xylose was carried out followed by analysis and i.r. characterisation. A subsequent analysis showed a dinuclear complex with a triple-bridge system. The ligand had been epimerized to the sugar lyxose which complexes in a furanose form with a very unusual conformation.
Finally a citric acid complex of ammonium molybdate was prepared and characterized. X-ray analysis was initially confused by a twinning problem. The final structure shows a tetranuclear centre for the metal atoms with two tetra-dentate citrate ligands. Hydrogen bonding is extensive.
