Giuliano Dolcetti

Metal–metal complexes with iridium–gold, iridium–copper, and rhodium–copper bonds

Metal–metal bonded complexes of the type [Cl2(CO)(PPh3)2Ir–AuPPh3], [Cl2(CO)M(PPh3)2Ir–Cu(PPh3)], [Cl2(CO)(PPh3)2Rh–Cu(PPh3)] obtained by reaction of RhI and IrI carbonyl derivatives of the type [Cl(CO)M(PPh3)2] with PPh3AuCl and PPh3CuCl in benzene or acetone are reported. Reactions of these complexes in benzene or dichloromethane with (i) Cl2, HCl, ICl, IBr (X–Y type), (ii) 1,2-bis(diphenylphosphino)ethane, 2,2′-bipyridyl (L–L type), carbon monoxide, and (iii) tetracyanoethylene, p-toluenesulphonyl chloride have been examined. The first type of reactants brings about cleavage of the metal–metal bond leading to the IrIII and RhIII derivatives [Cl2Y(CO)(PPh3)2MIII]. The second type leads to reductive elimination resulting in the IrI and RhI complexes of the type trans-[MI(PPh3)2(CO)Cl]. With the third type of reactant cleavage of the metal–metal bond occurs to give some well known 6-co-ordinate complexes.

Adducts of tertiary stibines with mercury(II) halides

The preparation of Lewis-acid–base adducts of the type R3SbHgX2(R = phenyl, o- and p-tolyl; X = Cl, Br, and I) are reported. Reaction of the o-tolylstibine with HgCl2 in benzene yields Hg2Cl2 and R3SbCl2. In tetrahydrofuran the reaction products are R2SbCl and RHgCl. These results are interpreted in terms of a scrambling occurring via a five-co-ordinate antimony labile intermediate formed via oxidative addition of the stibine by HgCl2.Reaction of R3Bi with HgCl2 leads to the scrambling products R2BiCl and RHgCl.

Preparation and reactivity of cationic platinum(II) hydrido-complexes

The preparation is reported of the cationic hydrides [Pt(PEt3) diphos (H)]Cl (I) and [Pt(PEt3)2(PR3)H]X (II)(R = Et or Ph; X = ClO4 or BF4) from the reaction of 1,2-bis(diphenylphosphino)ethane (diphos) or monodentate phosphine PR3 with trans-[Pt(PEt3)2(H)Cl] in benzene or dichloroethane. Conductivity and i.r. spectral data are given. The reaction of (I) with hydrogen chloride in dichloroethane leads to the complex [Pt(PEt3) diphos Cl]Cl with evolution of hydrogen. (I) reacts with SnCl2 in methanol to give the four-co-ordinate [Pt(PEt3) diphos H]-SnCl3.

Catalytic hydrogenation of non-activated olefins in the presence of iridium hydrido-complexes

The hydrogenation of non-activated olefins, i.e. ethylene and hex-1-ene by [Ir(PPh3)2H3] in dichloromethane at room temperature is reported. Under these experimental conditions [Ir(PPh3)3H3] is not effective. Hex-1-ene is hydrogenated in dichloromethane by molecular hydrogen under normal conditions in the presence of [Ir(PPh3)2H-(solvent)] acting as the catalyst; hex-2-ene is formed only in traces.