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Platinum(II) olefin compounds [PtMe(N,N′-imino, amide)(η2-olefin)] have been found to dimerize spontaneously in solution, yielding dinuclear complexes through an oxidative coupling. The extended conjugation within the molecules produces an intense blue color, and the properties of the compounds have been investigated through NMR spectroscopy, optical measurements, and theoretical calculations. The solid-state structure of a representative compound has been solved.

The coordinated olefin in dicationic platinum(II) and palladium(II) complexes [M(PNP)(olefin)](SbF6)2 (M = Pt, Pd; PNP = 2,6-bis(diphenylphosphinomethyl)pyridine; olefin = ethene, propene) is electrophilic enough to react with benzene rings activated by methoxy substituents. If the proton released by the aromatic ring is trapped by a base, stable σ-alkyl derivatives of the type [M(PNP)CH2CH(R)Ar](SbF6) or [M(PNP)CH(R)CH2Ar](SbF6) (R = H, Me) are formed; otherwise the M−C σ-bond can be cleaved by the proton, setting up a catalytic cycle that leads to the alkylated aromatic compound. The molecular structure of the σ-alkyl derivative [(PNP)PtCH2CH2−C6H2(OMe)3](BF4) has been determined by X-ray diffraction analysis, and the factors affecting the mechanism and the rates of the catalytic reaction have been qualitatively investigated and rationalized, showing that the rates of C−C bond formation and M−C bond cleavage are inversely correlated.

The ability of chiral diamine silver complexes to bind chiral and prochiral alkenes has been analyzed in detail. The stereoselectivity in binding of alkenes to a chiral ethanediamine silver complex has been investigated by NMR. The low-energy conformations of several small model complexes have been explored by DFT methods. By successive substitution of the computational model complexes, it has been possible to elucidate the role of each amine substituent in achieving successful discrimination of alkenes. The conformational space has been fully explored using small model systems, allowing an unbiased calculation of stereoselectivities that match well the experimental results. For a chiral allylic alcohol substrate, the correct stereoselectivity was obtained only when the structures were optimized with a continuum representation of the solvent. The discrepancy between gas phase and solution data is found to result from a competition between internal stabilization and solvation of the OH group of the substrate.

The dicationic palladium(II) and platinum(II) complexes [(PNP)M(C2H4)](BF4)2 (1a, M = Pt; 1b, M = Pd; PNP = 2,6-bis((diphenylphosphino)methyl)pyridine) and [(PPP)Pt(C2H4)](BF4)2 (7; PPP = triphos) catalyze a cross-coupling reaction of ethylene with tri- and tetrasubstituted olefins, which can lead to both hydrovinylation and cyclopropanation products. The product ratio is strongly affected by the choice of the ligand and of the metal, the two limiting cases being 1a and 7, which selectively give the hydrovinylation and the cyclopropanation products, respectively.

The fragment [(chiral diamine)Ag]+ is a very useful reagent, both for the resolution of racemic alkenes and for the 1H or 13C NMR determination of the enantiomeric abundances of chiral olefinic compounds.