The synthesis, coordination chemistry and catalytic applications of phosphinite, phosphonite and phosphite ligands containing perfluoroalkyl substituents

Abstract

A review is presented of the development and application of liquid-liquid biphase systems in homogeneous catalysis and the concept and application of fluorous biphase systems (FBS) in catalysis. Novel monodentate phosphorus(III) ligands of general formula PhxP(OC6H4-4-C6F,3)3.x and PhCHF-* (x = 0, 1 or 2), and the phosphite ligands P(OC6H4-4-C8Fl7)3, P(OC6H4-4-C10F2i)3, P(OC6H4-3-C6F13)3 and P(OC6H4-2-C6Fi3)3 have been synthesised and fully characterised by 'H, 19F and 3,P{lcub}1H{rcub} NMR spectroscopy, mass spectrometry and elemental analysis. The monodentate phosphinite, phosphonite and phosphite ligands (L) have been reacted with a variety of transition metal complexes to form complexes of the type cis- and trans- MC 2L2 (M = Pt, Pd), cw- PtCl2(PEt3)L , M(n5-C5Me5)Cl2L (M = Ir, Rh) and RI1CIL3 . The complexes have been isolated and characterised using analytical techniques including H, 19F and 31P{lcub}!H{rcub} NMR spectroscopy, mass spectrometry, IR spectroscopy, X-ray crystallography and elemental analysis. The steric and electronic influences of the perfluoroalkyl substituents on the chemical and physical properties of the metal complexes have been assessed by comparison of their spectroscopic and structural data with that for their related protio complexes. Preliminary catalytic studies involving P(OC6H4-4-C6Fi3)3 as a modifying ligand in the rhodium-catalysed hydroformylation of 1-hexene and 1-nonene under FBS conditions have been undertaken. The influence of the perfluoroalkyl substituents on the rate of reaction, product selectivity and catalyst/product separation has been examined. The synthesis of bidentate phosphonite and phosphite ligands containing perfluoroalkyl substituents has been investigated. The derivatised bidentate phosphonite ligands (C6F13-4-C6H40)2PCH2CH2P(OC6H4-4-C6F, 3)2 and {lcub}5,5' - (C6F13)2-2,2,-02C,2H6{rcub}PCH2CH2P{lcub}2,2,-02C,2H6-5,5,-(C6F13)2{rcub} (L-L) have been reacted with transition metal complexes to form coordination complexes of the type PtCl2(L-L) and Rh(u-C1)(L-L)]2