Sythesis, electrochemistry, phase studies and computational chemistry of gamma-substituted betadiketonato-carbonyl complexes of rhodium(I)

Synthetic routes to prepare β-substituted and γ-substituted β-diketones, rhodium(I)dicarbonyl and rhodium(I)monocarbonyltriphosphine complexes were developed and optimised, All complexes were characterised with 1H NMR, 31P NMR, and IR. Further characterisation of the complexes was done by means of the electrochemical techniques, DSC and POM. Cyclic voltammetry of the studied complexes shows irreversable chemical and electrochemical behaviour for both the reduction of the ligands and the oxidation of Rh(I). DFT calculations were used to optimise the neutral, the reduced, doubly reduced and triply reduced β-diketones, as applicable. Phase study of the synthesized compounds was done by means of a differential scanning calorimeter and a polarizing optical microscope. It was found that β-diketones exhibit different liquid crystalline mesophases before melting to an isotropic liquid. Rhodium(I)dicarbonyl complexes exhibit clear crystalline solid and isotropic liquid phase, while [Rh(β-diketonato)(CO)(PPh3)] has no crystal packing.