Pentacoordinated and hexacoordinated compounds

As in recent years, a lot more emphasis has been placed on understanding chemical and biological mechanisms in which pentacoordinated intermediates and transition states are involved. These include their role in the origin and evolution of life, the mechanisms of the phosphate transfers, the first step of Mitsunobu reaction, the formation of pentacoordinated species in the reactions of P-halogenylide with some carbonyl compounds and in the amidation of carboxylic acid mediated by the triphenylphosphine-iodine system. Pentacoordinated intermediates have also been postulated in the fluorination of glucose-like oxaphosphinane and in the mechanism of deoxygenative condensation of α-keto esters and carboxylic acids or as transition states in theoretical calculations of the catalytic activity of human tyrosyl-DNA phosphodiesterase I (hTdp1). There have been NMR studies of the configuration and internal rotation of selected spirophosphoranes. The chemistry of hexacoordinated phosphorus compounds has mostly concerned the explanation of the action of phosphoryl transfer enzymes, at the synthesis of novel macrocyclic derivatives and a series of salts bearing hexacoordinated phoshorus as well as at application of perfluorinated phosphate as a catalyst in the Diels–Alder reaction.