Bidentate phosphinophenol ligands. Preparation and electrochemistry of the Re(III) complexes of 2-(diphenylphosphinomethyl)-4-methylphenol (P 1OH) and 2-diphenylphosphinophenol (P 2OH). Crystal and molecular structure of mer-Re[P 1O] 3

• Published in: Inorganica Chimica Acta Vol. 306; no. 1; pp. 94 - 100
• Main Authors: Loiseau, Frédérique, Connac, Fabienne, Lucchese, Yolande, Dartiguenave, Michèle, Fortin, Sébastien, Beauchamp, André L, Coulais, Yvon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 11.08.2000
• Subjects: Crystal structures; Electrochemistry; Phosphinophenol complexes; Rhenium complexes; Electrochemistry; Crystal structures; Rhenium complexes; Phosphinophenol complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(00)00156-0

The reaction of 2-(diphenylphosphinomethyl)-4-methylphenol (P 1OH) and 2-diphenylphosphinophenol (P 2OH) on ReCl 3(MeCN)(PPh 3) 2 in a 3:1 ratio leads to the formation of the homoleptic Re(III) complexes Re(P 1O) 3 ( 1) and Re(P 2O) 3 ( 2) in high yield. 1 is reasonably stable in air in the solid state and in solution, which is not the case for 2. Orange–red crystals of 1 contain distorted octahedral Re entities in which the metal is coordinated to three bidentate phosphinophenolato ligands in the mer configuration. Cyclic voltammetry of 1 and 2 shows two well defined monoelectronic quasi-reversible redox waves, one reductive attributed to the Re(III)/Re(II) couple and one oxidative due to the Re(III)/Re(IV) one. A second oxidative wave, attributed to the Re(IV)/Re(V) couple, is reversible only for 1, indicating the lower stability of 2 toward oxidation. In agreement with this, 2 gives, in air, the Re(V)-oxo species ReO(OP 2O)(P 2O) 2 ( 3) quantitatively, whose structure is confirmed by X-ray diffraction.