Martin A. R. Smith

A new synthesis of platinum—carbon bonds

Abstract Syntheses of cis-[PtCl(CH2COCH3)(PEt3)2], cis-[PtCl(CH2NO2) (PEt3)2], and trans-[Pt(CCPh)2 (PEt3)2] are described. The procedure involves reaction of cis-[PtCl2(PEt3)2] with Ag2O and acidic CH bonds to precipitate AgC1 and generate a PtC bond. The method may represent a new general route to platinum—carbon bonds.

Trifluoromethylthio-complexes of platinum(II): measurement of trans-influence by fluorine-19 nuclear magnetic resonance spectroscopy

The synthesis and characterization of the following new complexes is reported: trans-[PtX(SCF3)(PEt3)2](X = Ph, Me, H, CF3, C2F3, CN, NO2, SCF3, N3, I, NCS, NCO, Br, Cl, or NO3), cis-[PtX(SCF3)(PEt3)2](X = NO2, SCF3, N3, NCS, NCO, Cl, or NO3), cis-[Pt(SCF3)2L2][L = PBun3, P(OPh)3, PPh3, P(OMe)3, PCIPh2, or C5H5N], trans-[Pt(SCF3)2L2](L = PBun3, PPh3, or C5H5N). trans-[Pt(SCF3)(CH3)(PPh3)2], and trans-[Ptl(CF3)(PEt3)2]. Values of 3J(Pt–F) in trans-[PtX(SCF3)(PEt3)2] and cis-[Pt(SCF3)2L2] complexes are used to establish a scale of trans-influence for the X and L ligands and the results are discussed in terms of existing theories of the Fermi contact interaction. It is concluded that an equation similar to those used previously for directly bound and two-bond couplings is still approximately valid for the longer-range 3J(Pt–F) couplings. The question of nonzero intercepts in plots comparing trans-influence scales derived from couplings to different indicator ligands is discussed. A perturbation approach to the problem shows that non-zero intercepts arise when the indicator ligands have different sensitivities to the perturbation. One possible cause of differing sensitivities is the polarizability of the indicator ligand.

cis- and trans-Influences in platinum(II) complexes. X-Ray crystal structure analysis of tetraethylammonium trichloro(triethylphosphine)-platinate(II)

Crystals of the title compound are monoclinic, space group P21/c, with Z= 4 in a unit cell of dimensions a= 1.03232(17), b= 0.92006(20), c= 2.27101(55) nm, β= 97.33(3)°. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to R 3.9%. The anion has bond angles at platinum within 1.4° of 90° and perturbations by interionic forces appear negligible. The 4° fold about the approximately linear P–Pt–Cl axis and the orientation of the PC3 moiety with respect to the complex plane are explained by C ⋯ Cl repulsions. The bond lengths Pt–P [221.5(4)], Pt–Cl (trans to P)[238.2(4)], and Pt–Cl [230.2(4), 229.9(4) pm] are compared with those in cis-[PtCl2(PMe3)2] and the Pt–P lengths are consistent with n.m.r. coupling constants 1J(Pt–P). Complexes of form [PtCl3L] are shown to be suitable as a basis for measurements of cis- and trans-influences of ligands L.

Synthesis, reactivity, and fluorine-19 nuclear magnetic resonance spectra of binuclear trifluoromethylthio-complexes of platinum and palladium

The preparation of [M2(SCF3)2(PR3)4]X2 complexes (M = Pd or Pt; R = Et or Ph; X = BF4 or ClO4) is described. 19F N. m.r. spectra of these complexes are used to assign structures and to demonstrate the existence of syn- and anti-isomers. Bridge-cleavage reactions with PR3 pyridine, p-toluidine, or chloride give monomeric species, cis-[Pt(SCF3)(L)(PR3)2]X or cis-[PtCl(SCF3)(PR3)2], and demonstrate theweakness of the SCF3 bridge compared to SR bridges (where R = hydrocarbon radical). The preparation of the unusual complex [Pt(SCF3)(ClO4)(PPh3)2] is also described.

Synthesis and fluorine-19 nuclear magnetic resonance spectra of trifluoromethylthio-complexes of platinum, palladium, nickel, and iridium

Oxidative addition reactions of (SCF3)2 to low oxidation state metal complexes and metathetical reactions of AgSCF3 with metal halide complexes lead to the synthesis of the new complexes cis- and trans-[Pt(SCF3)2(PPh3)2], cis- and trans-[PtCl(SCF3)(PPh3)2], trans-[PtH(SCF3)(PPh3)2], trans-[PtH(SCF3)(PEt3)2], cis-[PtCl(SCF3)-(PEt3)2], cis- and trans-[Pd(SCF3)2(PPh3)2], trans-[PdCl(SCF3)(PPh3)2], trans-[PdCl(SCF3)(PEt3)2], trans-[Ni(SCF3)2(PPh3)2] and trans-[Ir(SCF3)(CO)(PPh3)2]. 19F N.m.r. spectra of these complexes are described and used to assign the stereochemistry. The trans-influence of the SCF3 ligand is discussed and the platinum–fluorine coupling constants in a series of SCF3 complexes are used to establish a trans-influence series: H > PEt3∼ PPh3 > SCF3 > Cl.

Measurement of the trans influence in 1-platinacyclopent-4-ene-2,3-dione complexes : a proton, carbon-l 3, and phosphorus-31 nuclear magnetic resonance study

The preparation of a series of 1-platinacyclopent-4-ene-2,3-dione complexes [[graphic omitted]Hv][L =AsPh3, PPh3, PEt2Ph, PEt3, PMePh2, PMe2Ph, P(OPh)3, Ph2PCH2CH2PPh2(dppe), pyridine (py), 2,2′-bipyridine (bipy), or 1,10-phenanthroiine (phen)] is described. Measurement of the coupling 2J(PtHv) between the vinylic proton. Hv, and platinum is expected to provide a measure of the trans influence of L. Instead an apparent trans-influence order AsPh3∼ PPh3 > P(OPh)3 > PMePh2 > PEt2Ph > PMe2Ph > PEt3 > dppe > py is indicated, more or less the reverse of what is expected. Determination of 1J(Pt13Cv) from 13C n.m.r. spectra of a selection of the complexes. however, has indicated the correct order. Phosphorus-31 n.m.r. spectra of the complexes L = PEt3, PMePh2 and PPh3 indicate that the COCO half of the chelate has a considerably lower trans influence than the vinylic half.

Kinetics of ring opening of substituted cyclobutenediones by platinum(0) complexes

Kinetic data are reported for ring opening of benzocyclobutene-1,2-dione, 3-phenylcyclobutene-1,2-dione, 4-methoxy-3-phenylcyclobutene-1,2-dione, and 3,4-dimethoxycyclobutene-1,2-dione with the zerovalent platinum complexes [Pt(trans-PhCHCHPh)(PPh3)2] and [Pt(PhCCPh)(PPh3)2]. Possible mechanisms, intramolecular in chloroform and dissociative in benzene, are proposed in the light of these results.