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The synthesis of a range of phosphine-diamine, phosphine-amino-alcohol, and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterised by X-ray crystallography. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h−1 were observed at 85 °C. However, turnover is slow at near ambient temperatures. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of aromatic esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalised esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective reduction of the ester function in conjugated dienoate ethyl sorbate could deliver (2 E,4 E)-hexa-2,4-dien-1-ol, a precursor to leaf alcohol. The monounsaturated alcohol ( E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of CO over the diene is elusive. High chemoselectivity for the reduction of an ester over an alkyne group was observed in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymerisation reduction of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymerisations were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved. [ABSTRACT FROM AUTHOR]

The first ‘fluorous soluble’ metal complexes derived from a phosphino-amine are reported. Attaching a single perfluorinated ‘ponytail’ to the (C6F5)2P fragment is sufficient to give rhodium complexes that show high partition co-efficients between perfluoromethylcyclohexane and toluene. [Copyright &y& Elsevier]

The reaction of several tertiary amine functionalised phosphines with [Pt(COD)Cl2] has been studied. Reactions with ratios of L:Pt=2 proceeded cleanly to give either cis or trans complexes depending on the cone angle of the phosphines. The trans complexes could also be prepared by reaction with Zeise''s salt. Reactions of [Pt(COD)Cl2] with L:Pt=1 are less straightforward, and a mixture of cis and trans monodentate complexes, and in one example, a chelate complex have been isolated. The X-ray crystal structures of [PtCl2(η2-iPr2PN(Me)CH2CH2NMe2)] and a monodentate complex [trans-PtCl2(η1-iPr2PNH-c-NC5H10)2] are reported. [Copyright &y& Elsevier]

Ir complexes of chiral phosphine-diamine ligands catalyse the hydrogenation and transfer hydrogenation of aryl-piperidin-4-yl methanones, and ketones bearing both an aryl group and secondary alkyl substituent with up to 98% e.e., and with substrate to catalyst ratios of up to 4000. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of the very bulky phosphine ligands containing both tert-butyl and ortho-trifluoromethylphenyl substituents with [PdCl2(PhCN)2] have been studied, in order to assess the impact of steric and electronic effects on a ligand''s coordination ability. The palladium complexes of tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine and tert-butyl(ortho-trifluoromethylphenyl)(n-butyl)phosphine were characterised by X-ray crystallography and shown to be good precatalysts for the hydroxy- and alkoxycarbonylation of alkenes relative to Pd complexes of tricyclohexylphosphine and triphenylphosphine. A notable feature of Pd complexes of tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine is significantly enhanced regioselectivity relative to previous state-of-the-art catalysts in the hydroxycarbonylation of styrene, even if lithium chloride co-catalysts are not used. These catalysts derived from large cone angle ligands consistently give higher regioselectivity in the alkoxycarbonylation of styrene using ethanol, n-propanol, and i-propanol as nucleophiles. These Pd complexes are also active in the Suzuki coupling of activated aryl chlorides, and in both carbonylation and Suzuki reactions, tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine gives more productive catalysts than its bulkier analogues. [Copyright &y& Elsevier]

Abstract: Reaction of [Rh(CO)2](μ-Cl)]2 with bis-1,2-(di{4-dimethylaminophenyl)phosphino-ethane (L) gives the monomeric Rh(I) complex of type cis-[RhCl(L)(CO)] that was separated from a side product of type [Rh(L)2]Cl, and characterised by X-ray crystallography. This complex reacts with methyl iodide at high temperature to give the Rh(III) acetyl complex, [Rh(I)2(C(O)Me)(L)], which was also structurally characterised by X-ray crystallography. There is no sign of quaternisation of the dimethylamino groups under these conditions. This complex is soluble in organic solvent and insoluble in the polar media used in methanol carbonylation (AcOH/H2O/MeOH). However, in the presence of HI, this complex is readily soluble in AcOH/H2O/MeOH, in contrast to [Rh(I)2(C(O)Me)(dppe)] and most other Rh-acetyl complexes of diphosphine ligands. [Copyright &y& Elsevier]