PdCl2 Complexes Research Articles

Phosphinohydrazines. Part III. Coordination compounds of N,N-dimethyl,N′-diphenylphosphinohydrazine and N,N-dimethyl,N′-diphenylthiophosphinatohydrazine

Reactions between N,N-dimethyl,N′-diphenylphosphinohydrazine, Me2NNHP(C6H5)2, (DPH), or N,N-dimethyl,N′-diphenylthiophosphinatohydrazine, Me2NNHP(S) (C6H5)2, (DPS), and appropriate metal salts have yielded the new coordination complexes Pd(DPH)Cl2, Pd(DPH)2Cl2, Pd(DPH)2Cl(ClO4), Pt(DPH)2Cl2, Pt(DPH)Cl4, Hg(DPH)Cl2, Pd(DPS)Cl2, Pt(DPS)Cl4, Ag(DPS)NO3, Zn(DPS)Cl2, Cd(DPS)Cl2, and Hg(DPS)Cl2. Notably, complexes of 1:1 ligand:metal stoichiometry predominate, the only exceptions being Pd(DPH)2Cl2 and Pt(DPH)2Cl2. In reactions between DPH and Zn(II) or Cd(II) salts, ready cleavage of the P—N bond was observed; the metal complexes of dimethylhydrazine were isolated in both instances. With the ligand DPS, however, the P—N bond was consistently stable against cleavage. Many reactions involving Co(II), Ni(II), Ag(I), Au(III), In(III), and Sn(II) resulted in the formation of intractable oils, or in reduction to the metallic state.

Sulphur-nitrogen chelating agents. IV. Metal complexes of o-methylthioaniline

Complexes of o-methylthioaniline (NH2-SMe) have been obtained with nickel(II), palladium(II), platinum(II), and copper(II). They are of the following types: NiX2(NH2-SMe)2 (X = Cl, Br, I); PdX2(SH2-SMe) (X = Cl, Br, I, SCN); PdCl2(NH2-SMe)2; [Pd(NH2-SMe)2](PF6)2; PtX2(NH2-SMe) (X = Br, I, SCN); [Pt(NH2-SMe)2][PtCl4]; and CuX2(NH2-SMe) (X = Cl, Br). A conductimetric titration of [Pd(NH2-SNe)2]2+ with iodide ion in nitrobenzene solution shows that one molecule of ligand is displaced to give PtI2(NH2-SMe). If the complexes PdCl2(NH2-SMe) and [Pt(NH2-SMe)2][PtCl4] are heated in dimethylformamide, S-demethylation of the ligand occurs to yield the thiolo-bridged complexes M2Cl2(NH2-S)2(M = Pd, Pt). The nickel complex NiI2(NH2-SMe)2 is not demethylated under the same conditions.

Nuclear magnetic resonance studies in coordination chemistry. Part II: Kinetic studies of reactions occurring in the system [(π‐C4H7)PdCl]2‐triphenylarsine

AbstractAn NMR study has been made of the reactions occurring in systems which contain either the monomeric complex (π‐C4H7)PdCl(Ph3As) and the dimer [(π‐C4H7)PdCl]2, or only monomer and free triphenylarsine (in CDCl3). In the former case reactions were observed of Ph3As ‐ formed by the dissociation of the monomer (reaction (a)) ‐ with the dimer (b) and the monomer (c), respectively: In the latter case, where only monomer and Ph3As are present, two reactions were studied. The first, which was observed between ‐70° and ‐40° with a very small excess of Ph3As, and which involves the exchange of Ph3As (reaction (c)), is first‐order in the arsine ligand. This reaction and the reactions in the presence of dimer were studied by measuring the rates at which the syn‐protons (or the anti‐protons) of the allyl group become magnetically equivalent. The second reaction, in which also exchange of Ph3As takes place, was measured between +10° and +80° with a higher excess of free Ph3As. This reaction is also first‐order in Ph3As, but involves the formation of either a s̀‐allyl intermediate or an activated state resembling the s̀‐allyl form. The activation energies and frequency factors of the above reactions are reported.At still higher excess of Ph3As (Ph3As/Pd ∼ 2‐3) an equilibrium (π‐C4H7)PdCl(Ph3As) + Ph3As ⇆ [(π‐C4H7)Pd(Ph3As)2]+Cl− becomes notticeable. This equilibrium moves to the right with increasing Ph3As/Pd ratio and decreasing temperature. The amount of ionic species, however, is so small that the kinetics of the above reactions are but little influenced by it.

Nuclear magnetic resonance studies in coordination chemistry. I: Structure and conformational rearrangements of π‐allyl complexes containing group‐V donor ligands

AbstractNuclear magnetic resonance has been employed to investigate the structure of the complexes (π‐allyl) PdCl(L) (L = phosphine, Ph3As, Ph3Sb) and the conformational rearrangements of the allyl group in these compounds as affected by the ligand, the ligand‐to‐metal ration and the temperature (in CDCl3).Several types of rearrangement were observed, depending on the choice of the variables mentioned above. At low temperatures a short‐lived σ‐allyl intermediate was found in the case of the phosphines only, whereas at higher temperatures rotation of the π‐allyl group was inferred for all the ligands. At very high temperatures and high ligand‐to‐metal ratios a σ‐allyl group had to be postulated to explain the NMR spectra, which are analogous to those of σ‐allyl‐magnesium halide compounds.A molecular orbital description has been used to rationalize some of the experimental results.