SYNTHESIS AND ELECTROCHEMICAL STUDY OF A NEW DOUBLY-METALATED COMPOUND WITH THE FERROCENE-LABELED PHOSPHINE PPH2(C5H4)FE(C5H5)

Direct reaction of the metallated compound Rh2(mu-O2CCH3)3[mu2-(C6H4) PPh2].(H2O)2 with PPh2Fc [Fc = (C5H4)Fe(C5H5)] in chloroform solution yields the corresponding mono-adduct Rh2(O2CCH3)3[(C6H4)PPh2].(PPh2Fc) (1), which has been characterized by P-31 NMR spectroscopy. Photochem ical irradiation of 1 in chloroform gives the compound 2CCH3)2(eta2-O2 CCH3)[mu2-(C6H4)PPh2][PPh2Fc].(H2O) (2) in practically quantitative yi eld. Compound 2, by thermal treatment in chloroform solution, yields c leanly the doubly-metallated compound 2-O2CCH3)2[mu2-(C6H4)PPhFC][mu2- (C6H4)PPh2].(H2O)2 (3). Complex 3 acts as a multiple electron-transfer system, showing by cyclic voltammetry in CH2Cl2 two well-defined one- electron oxidation processes: the first at 0.52 V, assigned to the red ox couple Fe(II)/Fe(III), and the second at 1.00 V, due to the redox c ouple Rh-2(+4)/Rh-2(+5).