Reactions of methylene active compounds with peroxo-rhodium phosphino complexes. Formation of hydro-peroxorodhium complexes.

Reactions of active methylene compounds HA (malononitrile, \u3b2-diketones, cyclopentadiene) with the dioxygen adduct [Rh(dppe)O2]BF4 give new hydroperoxorhodium(III) complexes of the type [Rh(dppe)(A)OOH]BF4. The complexes readily convert PPh3 into OPPh3, but do not oxidise ketones or olefins, which instead undergo extensive isomerization

Thermolysis mechanism of monoalkylplatinum(II) complexes with tertiary phosphine ligands. Methyl radical elimination from trans-Pt(I)(CH3)[P(CH3)3]2.

Thermolysis of the complexes trans-Pt(I)(Me)(PR3)2 (R = CH3, CD3, C2H5, C6H5, C6H11, Me = CD3) in deuterated or non-deuterated hydrocarbons at 120\ub0C produces MeH and/or MeD. Appropriate isotopic labeling has revealed the existence of two decomposition pathways. The main route involves homolytic splitting of the platinum-methyl bond to give methyl radicals, which then form methane by abstraction of hydrogen from the R groups of the phosphines or from the solvent. The second, less important, route has a molecular mechanism involving coordinate methyl groups

Thermal Stability of the organopalladium compounds. Non radical methyl elimination from [PdXMe(PEt3)2].

The thermolysis of the palladium complexes [PdX(Me){P(C2H5)3}2] (X = Br, I, CN; Me = CH3, CD3) in decalin or toluene under argon, in the temperature range 120–160°C, produces methane, ethane and ethylene, in ratios which vary with the temperature. Deuterium labelling shows that the methane is mainly formed through intramolecular abstraction of hydrogen from the phosphine ligands by the coordinated methyl group and not through homolytic fission of the PdMe bond. The thermal stability and the decomposition mechanisms of the organopalladium complexes are compared with those of the platinum analogues, which are remarkably more stable. At the higher temperatures, the thermal decomposition involves cleavage of the PEt bonds in the phosphine ligands, and this leads to the formation of ethane and ethylene. The rate of generation of methane from the PdMe moieties is increased by a factor of 10 by the presence of an excess of dioxygen. Deuterium isotopic labelling shows that the rate increase is accompanied by a change from an intramolecular to a radical mechanism involving the abstraction of hydrogen by the methyl groups

Allylplatinum and platinum(O) complexes with phosphorus-sulfur mixed ligands.

Monomeric \u3b71-allyl complexes [PtCl(C3H5)(PSR)], (PSR = Ph2P(CH2)2SR, R = Me, Ph) are rapidly converted in polar media into the \u3b73-allyl derivatives [Pt(C3H5)(PSR)]BF4. The NMR characteristics of both types of complex are discussed

Halogen chemistry.

A large number of halogenated organics have been produced commercially in the past few decades, which have been used for a variety of purposes. The quest for enviromentally friendly technology in general has risen to a substantial thrust to get away from chlorocarbons and halogenated materials altogether, due to the generic deleteriousness associated to them. Halogenated compounds continue to be produced and utilized, however, as they still remain both the best solvents for some high-tech processes and flexible starting materials for a variety of organic syntheses

HYPOCHLORITE-OXYFUNCTIONALIZATION OF SATURATED-HYDROCARBONS CATALYZED BY RUTHENIUM(II) COMPLEXES

Hydroxylation or ketonization of alkanes is achieved using lithium or sodium hypochlorite in the presence of catalytic amounts of ruthenium(II) complexes in a biphasic dichloromethane-water system, at room temperature. The oxidation of cyclooctane is first order both in substrate and in catalyst: a kinetic isotope effect (k(H)/k(D)) = 5.6 was measured using cyclohexane-d12. A discussion is included concerning the origin of the different regioselectivities

Ruthenium(II) catalysts for the homogeneous oxygenation of aliphatic hydrocarbons and ethers.

Hydroxylation or ketonization of alkanes and selective conversion of ethers to esters or b-keto-ethers are achieved with hypochlorite and a choice of ruthenium(II) complexes as catalysts, in a biphasic water-dichloromethane system

Mechanism of oxidative addition of benzonitriles to di[1,4-bis(diethylphosphino)-butane]nickel(0).

A kinetic study of the oxidative addition of RC6H4CN (R = H, m-CN, p-CN) to Ni(DEPB)2 (DEPB = 1,4-bis(diethylphosphino)butane) suggests a template mechanism leading to the fission of one C-CN bond. The reaction products are trans-planar cyano-organonickel(II) complexes, Ni2(\u3bc-DEPB)2(RC6H4)2(CN)2 and Ni(\u3b71- DEPB)(RC6H4)(CN), in equilibrium. through exchange of DEPB