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

Abstract

• Phosphorous(V) corroles exist in penta-hexa coordination in non-coordinating solvents. • Hexa-coordinated geometries were obtained in coordinating solvents. • Solid state geometries prefer to be in hexa-coordinated systems. • 31 P, 1 H and 19 F NMR provide proof for penta-hexa behavior. ABA (where A = nitrophenyl, and B = pentafluorophenyl group) corrole was isolated as hexacoordinate P(V) complexes that contained two axial hydroxyl groups. NMR spectroscopy ( 1 H, 19 F and 31 P) in CDCl 3 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 CH 3 OH and CD 3 OD, 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 CHCl 3, CH 2 Cl 2 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 -OCH 3 groups were confirmed by X-ray crystallography.