STRUCTURAL AND ELECTRONIC IMPACT OF FLUORINE IN THE ORTHO POSITIONS OF THE PHENOXY GROUPS OF PHENYL-PHOSPHONITE AND PHENYL-PHOSPHINITE LIGANDS IN COMPOUNDS OF PLATINUM-GROUP METALS

The phosphonites PPh(OPh)(2) I and PPh(OC6H3F2-2,6)(2) II, and the pho sphinites PPh2(OPh) III and PPh2(OC6H3F2-2,6) IV reacted with [{RhCl(m u-Cl)(eta(5)-C5Me5)}(2)] to yield the complexes [RhCl2L(eta(5)-C5Me5)] [L = PPh(OPh)(2) 1, PPh(OC6H3F2-2,6)(2) 2, PPh2(OPh) 3 or PPh2(OC6H3F 2-2,6) 4]. The perprotio-phosphonite and -phosphinite, I and III, reac ted with [{PtCl(mu-Cl)(PEt3)}(2)] to yield exclusively the cis isomers of [PtCl2(PEt3){PPh(OPh)(2)}] 5 and [PtCl2(PEt3){PPh2(OPh)}] 7. The f luorine-containing phosphonite and phosphinite, II and IV, reacted wit h [{PtCl(mu-Cl)(PEt3)}(2)] to give the trans isomers of [PtCl2(PEt3){P Ph(OC6H3F2-2,6)(2)}] 6a and [PtCl2(PEt3){PPh2(OC6H3F2-2,6)}] 8a, which isomerize slowly in acetone solution to yield the cis isomers 6b and 8b. Values of (1)J(RhP) and (1)J(PtP) strongly suggest that the presen ce of fluorine atoms in the ortho positions of the phenoxy groups has a negligible effect on the electronic properties of the phosphorus ato ms of these ligands. X-Ray single-crystal structural studies on 1, 4, 6a, 6b, 7, 8a and 8b revealed that the fluorine atoms do, however, exe rt a profound steric influence.