Kenneth C. Moss

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.

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.

Oxidation and reduction of some tungsten, molybdenum, and vanadium chlorides by chlorinated alkyl cyanides

Tungsten(V) chloride is oxidised by trichloroacetonitrile to give a tungsten(VI) complex containing a tungsten-nitrogen triple bond. CCl3·CCl2NWCl4,CCl3CN; tungsten(VI) chloride gives the same complex with trichloroacetonitrile and analogous complexes with monochloroacetonitrile and 1-cyano-1,1,2-trichloroethane. The i.r. spectra of molybdenum(V) complexes formed in the reactions of trichloroacetonitrile with molybdenum(V) chloride and molybdenum(IV) chloride are interpreted on the basis of a triple molybdenum–nitrogen bond being formed. Molybdenum(V) oxytrichloride forms simple adducts with trichloroacetonitrile, but no complex could be isolated from the reaction of this ligand or 1-cyano-1,1,2-trichloroethane with vanadium(IV) chloride; this halide was reduced with mono- or di-chloroacetonitrile to give vanadium(III) adducts VCl3,3L.

The oxidation of titanium(III) chloride by chlorinated alkyl cyanides

Monochloro-, dichloro-, and trichloro-acetonitrile and 1-cyano-1,1,2-trichloroethane oxidise titanium(III) chloride to yield titanium(IV) chloride–alkyl cyanide complexes. The organic reaction products were isolated from the reaction media. A mechanism for the oxidation and structures for the complexes are proposed.