Peter J. Thompson

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.

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.

Reactions and properties of some trimethyleneplatinum(IV) complexes: VII. Kinetics and mechanism of displacement of cyclopropane by alkenes☆

The kinetics of the reaction of alkenes (e.g. cis-pent-2-ene, hex-1-ene, cyclopentene) with [PtX2(CH2CH2CH2)(THF)2] (X = Cl or Br, THF = tetrahydrofuran) or with [PtCl2(CHPhCH2CH2)(THF)2] in THF solution have been studied. The reactions occur with displacement of cyclopropane or phenylcyclopropane to give [PtCl2(olefin)(THF)], and follow essentially second order kinetics, first order in both platinum complex and olefin. The mechanism of reaction is discussed.

Isomerisation in the chemistry of platinacyclobutane complexes

Abstract The platinacyclobutane complexes PtCl2L2(C3H5Me)], L  pyridine, CD3CN, or tetrahydrofuran, exist as mixtures of isomers containing P tCH 2 CHMeC H2 or P tCHMeCH 2 CH 2 groups in rapid equilibrium. Decomposition occurs in some cases to give [PtCl2L(CH3CH2CHCH2)]. Stereospecific skeletal isomerisation also occurs in metallocyclobutanes containing the groups P tCHRCHRC H2  P tCHRCH 2 C HR, when R  aryl further decomposition gives ν-allylplatinum complexes.

Catalysis of methyl for halogen exchange reactions in platinum(II) complexes

The symmetrisation reaction between cis-[PtMe2 (PMe2Ph)2] and cis-[PtCl2-(PMe2Ph)2] to give cis-[PtClMe(PMe2Ph)2] is catalysed by [Pt2Cl2 (μ-Cl)2-(PMe2Ph)2].

Magnetic double-resonance studies of platinum-195 chemical shifts in organoplatinum compounds

Platinum-195 chemical sifts and coupling constants obtained by 1H-{31P} and 1H-{195Pt} double resonance are reported for 78 platinum compounds, of which most have direct platinum–carbon bonds. Empirical trends are noted and where possible assessed in terms of current theories. Electronic excitation energy, interbond angle, and substituent bulk and/or polarizability all appear to make significant contributions to the 195Pt nuclear shielding.

Retention of stereochemistry at both platinum centres in the symmetrisation reaction between cis-[PtMe2(PMe2Ph)2] and cis-[Pt(NO3)2(PMe2Ph)2]

Reaction of cis-[PtMe2(PMe2Ph)2] with cis-[Pt(NO3)2(PMe2Ph)2] in dichloromethane solution gives only cis-[PtMe(NO3)(PMe2Ph)2] which then isomerises slowly to the more stable trans-isomer.

Observation by electron spin resonance spectroscopy of free radicals in reaction of dialkylplatinum(II) complexes with alkenes

Free radicals are formed under mild conditions, and have been identified by e.s.r. spectroscopy, in reactions of dialkyplatinum(II) complexes with alkenes.

The chemistry of the trivalent actinoids. Part 5. Uranium(III) complexes with bidentate organic amides

Uranium(III) forms air-sensitive tetrakis complexes with the amides Me2N·CO·[CH2]n·CO·NMe2 and Me2N·CO·CH2·CMe2·CH2·CO·NMe2[series (I; n= 1–4)] and Et2N·CO·[CH2]n·CO·NEt2 and Et2N·CO·CH2·CMe2·CH2·CO·NEt2[series (II; n= 1–4)] using [BPh4]– or [PF6]– as the counter anion. The i.r. spectral results indicate interaction through the ligand oxygen atoms and non-participation of the anions in co-ordination, leading to the UO8 chromophore which has low symmetry. The complexes are black, mauve, or green. Differences in the energies of f–d transitions are explained in terms of nephelauxetic effects. Similar changes have been observed in the energies of bands observed at shorter wavelengths, which are assigned to metal ion-to-ligand electron transfer. The spectra of NNN′N′-tetramethyldiamide and corresponding NNN′N′-tetraethyldiamide complexes are not noticeably different, indicating that changes in the N-alkyl substitution pattern may have little effect on amide base strength. The magnetic properties of the NNN′N′-tetramethylmalonamide complex with tetraphenylborate are normal for UIII with µeff.(294 K)= 2.97 B.M. With 4,4′-methylenebis[1,5-dimethyl-2-phenylpyrazol-3(2H)-one], air-sensitive, lilac-mauve, tris complexes have been prepared with the same anions. The change in stoicheiometry is attributed to steric effects but, apart from a broadening of the f–d transitions, there are no obvious spectral effects which distinguish the UO6 chromophore.

Alkyl-exchange reactions and their catalysis in platinum(II) complexes

A study of the symmetrisation reactions ot [PtR2L2] with [PtX2L2] to give [PtXRL2] has been made (R = Me, Ph, or CCMe; L = PEt3, PMe3, PMe2Ph, or AsMe3; X = Cl, I, NCS, NO2, or NO3). The dependence of the reaction rate and stereochemistry on the substituents R, X, and L has been studied and the reaction mechanism is discussed. The reaction of cis-[PtCl2(PMe2Ph)2] with cis-[PtMe2(PMe2Ph)2] to give cis-[PtClMe(PMe2Ph)2] is catalysed by [Pt2Cl4(PMe2Ph)2], but the catalyst is destroyed in a competing reaction with cis-[PtMe2(PMe2Ph)2] to give cis-[Pt2(µ-Cl)2Me2(PMe2Ph)2].