The synthesis of the tripodal phosphine CH3C{CH2P(m-CF3C6H4) 2}3 and its rhodium coordination chemistry

Abstract

The new tripodal phosphine CH3C{CH2P(m-CF3C6H4) 2}3, CF3PPP, was prepared by reacting CH3C(CH2Br)3 with Li+P(m-CF3C6H4)2 -, the latter being best obtained by adding Li+NiPr2- to PH(m-CF3C6H4)2. The rhodium complexes [RhCl(CO)(CF3PPP)], [Rh(LL)(CF3PPP)](CF3SO3) (LL=2 CO or NBD), [RhX3(CF3PPP)], [RhX(MeCN)2(CF3PPP)](CF3SO3) 2 (X=H and Cl), [RhCl2(MeCN)(CF3PPP)](CF3SO3) and [Rh(MeCN)3(CF3PPP)](CF3SO3) 3 were prepared and characterized. The X-ray crystal structure of [Rh(NBD)(CF3PPP)](CF3SO3) is reported. The lower oxygen sensitivity of the CF3PPP rhodium(I) complexes, relative to the corresponding species with the parent ligand CH3C(CH2PPh2)3, is attributed to the higher effective nuclear charge on the metal centers caused by the presence of the six CF3 substituents on the terdentate phosphine. A similar effect may be responsible for the easier hydrolysis of the CF3PPP-containing, cationic rhodium(III) complexes relative to the corresponding compounds of the parent ligand. © 1998 Elsevier Science S.A.