Passing Me over: platinum-to-copper methyl transfer is observed upon collision-induced dissociation (CID) of the cations formed by the interaction of the [(R(3)P)Cu](+) fragment with [(dmpe)PtMe(2)] (R=Me, Ph, Cy, tBu; dmpe=bis(dimethylphosphino)ethane; see X-ray crystal structure of coordination spheres for R=tBu). The thermochemistry of these processes for R=Me is investigated by mass-spectrometric methods.

A series of new, dicationic platinum(II) CNC pincer complexes were prepared and characterized by NMR and X-ray diffraction analysis. Oxidative addition of methyl iodide and iodine yielded the mostly unstable platinum(IV) complexes, which readily underwent reductive elimination to yield the platinum(II) precursors. Nonetheless, a platinum(IV) iodide adduct was isolated and was characterized by X-ray diffraction analysis. Additionally, a platinum(II) ethylene complex was isolated and found to be a moderately active yet highly selective catalyst in the co-dimerization of 2-methyl-2-butene with ethylene.

In the present study we describe the efficient synthesis of various Au(I) complexes supported by NHC ligands. Some of these ligands have a pendant pyridine arm that is linked with various tethers (CH 2 ) n to the NHC backbone (n = 0-2). The chloride in the Au(I) complexes is easily and cleanly replaced by an aryl group upon reaction with an aryl-Grignard reagent. The thus obtained aryl Au(I) complexes are cleanly oxidized to the corresponding Au(III) complexes with phenyliodoso dichloride, as are the corresponding halide Au(I) complexes. The attempted salt metathesis with the parent Au(III) complex led to the oxidative coupling of the aryl residues with formation of the Au(I) complex. Some of the complexes are promising catalysts in the cycloisomerization of an ω-alkynylfuran to isobenzofuranol in the presence of a silver salt. For those precursors with pendant pyridine arms, a cationic dimeric Au complex was isolated and characterized, which represents a catalyst resting state and forms under reaction conditions.

We report Pt(II)-to-Au(I) methyl transfer reactions that occur in the gas phase and in solution. The heterobimetallic Pt(II)/Au(I) complexes {[(dmpe)PtMe(2)][AuPR(3)]}(+) (R = Me (2a), Ph (2b), (t)Bu (2c)), observed in the gas phase by means of electrospray ionization, were subjected to collision induced dissociation (CID) from which we could observe Pt-to-Au transmetalation along two reaction pathways involving formation of a Au-Me bond, analogous to those observed for the Pt(II)/Cu(I) complex recently reported. In the first pathway, neutral AuMe is generated with concomitant migration of PR(3) from Au(I) to the Pt(II) center, forming cation [(dmpe)PtMe(PR(3))](+) (R = Me (5a) or Ph (5b)). In the second pathway, the monophosphine stays attached to the gold center, yielding cation [(dmpe)PtMe](+) (7) and R(3)PAuMe. Quantitative energy-resolved collision induced dissociation experiments as well as density functional theory (DFT) calculations were used to investigate the potential surface involved in the transmetalation processes. Energy barriers of 22.3 and 47.9 kcal mol(-1) for the two reaction processes of 2b and of 45.4 kcal mol(-1) for the single reaction process of 2c were obtained. Parallel reactivity is observed in THF solution, allowing for a comparison of the product distributions with those observed in the gas phase, and the postulation of simple steric control of the branching ratio between the two pathways. DFT calculations at the M06-2X//BP86/TZP level were in good agreement with the experiments.

Carbonyl-containing Ru and Fe heterobimetallic complexes were prepared and tested as electrocatalysts for the oxidation of methanol and ethanol. GC analysis of the electrolyte solution during bulk electrolysis indicated that CpRu­(CO)­(μ-I)­(μ-dppm)­PtI2 (1), CpFe­(CO)­(μ-I)­(μ-dppm)­PtI2 (2), and CpRu­(CO)­(μ-I)­(μ-dppm)­PdI2 (3) were catalysts for the electrooxidation of methanol and ethanol, while CpFe­(CO)­(μ-I)­(μ-dppm)­PdI2 (4), CpRu­(CO)­I­(μ-dppm)­AuI (5), and CpFe­(CO)­I­(μ-dppm)­AuI (6) did not function as catalysts. The oxidation of methanol resulted in two- and four-electron oxidation to formaldehyde and formic acid, respectively, followed by condensation with unreacted methanol to yield dimethoxymethane and methyl formate as the observed products. The oxidation of ethanol afforded 1,1′-diethoxyethane as a result of two-electron oxidation to acetaldehyde and condensation with excess ethanol. FTIR analysis of the headspace gases during the electrochemical oxidation of methanol indicated formation of CO2. Isotopic labeling experiments demonstrated that the CO2 resulted from oxidation of the CO ligand instead of complete oxidation of CH3OH.