R.J. Puddephatt

Preparation and electronic spectra of some alkyl- and aryl(2,2′-bipyridine)platinum(II) complexes

Abstract A series of alkyl- and aryl-(2,2′-bipyridine)-platinum (II) complexes has been prepared by displacement of the diene ligand in the corresponding cyclooctadiene complexes with 2,2′-bipyridine. Dimethyl(1,10-phenanthroline)platinum(II) was prepared in an analogous way. The electronic spectra of the complexes contain metal to ligand charge transfer bands whose energy is dependent on the nature of the substituents on platinum and on the solvent. It is suggested that π-bonding is important in the phenyl—platinum bond.

Some reactions of methylplatinum and methylgold compounds with phenylselenol, diphenylphosphine, diphenylarsine, N-bromosuccinimide and 2-nitrophenylsulphenyl chloride

Abstract Phenylselenol, diphenylphosphine and diphenylarsine react with methyl derivatives of platinum(II), gold(I) and gold(III) to cleave the methyl—metal bond, but N -bromosuccinimide and 2-nitrophenylsulphenyl chloride oxidise methylplatinum(II) complexes to methylplatinum(IV) complexes without cleavage of the methyl-platinum bonds.

Solvent effects on the rate of oxidative addition of methyl iodide to diphenyl(2,2′-bipyridine)platinum(II)

Abstract The reaction of methyl iodide with diphenyl(2,2′-bipyridine)platinum(II) to give iodo(methyl)diphenyl(2,2′-bipyridine)platinum(IV) follows the rate law, rate = k 2 [PtPh 2 (2,2′-bipyridine)][MeI]. The values of k 2 increase with increasing polarity of the solvent suggesting a polar transition state for the reaction.

Oxidative addition reactions of methyl iodide with some methylgold(I) compounds

Abstract Reactions of methyl iodide with MeAuL (L = PMe 3 , PMe 2 Ph or PMePh 2 ) rapidly give an equimolar mixture of Me 3 AuL and IAuL. A slower reaction then takes place to give cis -Me 2 AuIL when L = PMe 3 or PMe 2 Ph and a mixture of cis -Me 2 AuIL (and the products of its subsequent reaction with methyl iodide) and IAuL + C 2 H 6 when L = PMePh 2 . The kinetics of the reactions when L = PMe 3 have been studied, and possible mechanisms are discussed.

1H,13 and 195Pt NMR studies of some platinumcyclopropane compounds

The 1H, 13C and 195Pt NMR spectral parameters of some platinum—cyclopropane complexes are reported. The NMR parameters, particularly the 13CH coupling constants, suggest the presence of a PtCH2CH2CH2 ring in these compounds. However, there is probably some interaction between platinum and the β-carbon atom acioss the 4-membered ring.

Platinumolefin bond strength in Pt(PPh3)2(CH2CH2) and Pt(PPh3)2 {C(CN)2C(CN)2}

Abstract The enthalpy of the reaction: Pt(PPh 3 ) 2 (CH 2 CH 2 )(cryst.) + C(CN) 2 C(CN) 2 (g) → Pt(PPh 3 ) 2 {C(CN) 2 C(CN) 2 }(cryst.) + CH 2 CH 2 (g) has been determined as Δ H 298 =−155.8±8.0 kJ·mol −1 , from solution calorimetry. The interpretation, that the platinumethylene bond is much weaker than the platinumtetracyanoethylene bond, is contrary to conclusions drawn recently from electron emission spectroscopic studies, but in agreement with available structural data.

Organolead chemistry : III. 207Pb chemical shifts in some organolead compounds☆

207Pb chemical shifts are reported for the compounds (CH3)4−nPb Xn, where n = 1 · 4, X = 4-FC6H4; n = 1, 2, 4, X = CH3 CC; n = 1, 4, X = CH2CH; n = 1, X = Cl, CH3O, CH3CO2. A correlation between δ(207Pb) and δ(19F) for the 4-fluorophenyl derivatives is discussed, and solvent effects on δ(207Pb) for the propynyl derivatives are interpreted in terms of complex formation.

Methyl transfer reactions between platinum(II) and platinum(IV) complexes and some apparent methyl for hydride exchange reactions

Abstract cis-[PtMe2(PM2Ph)2] reacts with [PtX2Me2(PMe2Ph)2] (X = I, NO2, NO3) to give [PtXMe(PMe2Ph)2] and [PtXMe3(PMe2Ph)2]. When X = I, the isomer cis-cis-trans-[PtX2Me2(PMe2Ph)2] fails to react with cis-[PtMe2(PMe2Ph)2] through the trans-cis-cis isomer does react. By labelling studies, it is shown that when X = NO3 the reaction occurs by methyl for nitrate exchange rather than by a redox mechanism, though when X = NO2 the situation was more complex. trans-[PtIHL2] (L = PMe3 or PMe2Ph) reacted with [AuMeL] or cis-[PtMe2L2] to give trans-[PtIMeL2], a reaction which appears to involve methyl for hydride exchange.

Photolysis of di-η5-cyclopentadienyldimethyltitanium(IV): application of free-radical polymerization in a study of the mechanism

Photolysis of di-η5-cyclopentadienyldimethyltitanium(IV) (λ 435.8 nm) leads to the initiation of free-radical polymerization. Labelling studies reveal that no free methyl is formed on photolysis and it is suggested that initiation occurs through interaction with monomer of a labile-photolysis product containing titanium.

Reactions and properties of some trimethyleneplatinum(IV) complexes

Summary The photolysis of platinum-cyclopropane compounds, [X2PtCH2CH2CH2(L L)][where X = Cl, Br and L L = 2,2′-bipyridine, 1,10-phenanthroline] in solution at 25°C gives cyclopropane (plus a little propene) and [X2Pt(L L)]. The kinetics indicate that the C3H6moiety is ejected from the excited molecule in a single step.