Penta -hexa coordination behaviour of ABA-P(V) corrole

Abstract ABA (where A = nitrophenyl, and B = pentafluorophenyl group) corrole was isolated as hexacoordinate P(V) complexes that contained two axial hydroxyl groups. NMR spectroscopy (1H, 19F and 31P) in CDCl3 indicated that the hexacoordinated P(V) complexes were prone to axial-ligand dissociation to form pentacoordinated P(V) complexes. Although, in the presence of strong coordinating solvents, such as CH3OH and CD3OD, the P(V) corrole complexes were observed to exist in a hexacoordinated geometry in which the strong solvent molecules acted as the ligands at the axial position. Also, we report here the existence of the hexacoordinated P(V) complexes in non-coordinating solvents such as CHCl3, CH2Cl2 by using fluoride and methyl substituted silyloxy groups acting as the ligands at the axial position. Moderately bulky nature and electron-donation effect of silyloxy groups proved to be of great aid to prevent the axial ligand dissociation of silyloxy substituted hexacoordinated P(V) complex and strong P-F bond in non-coordinating solvents. The structure of hexacoordinate P(V) complex containing two axial -OH groups and hexacoordinate P(V) complex containing two axial -OCH3 groups were confirmed by X-ray crystallography.