Martin J. Hanton

A 1,1′-ferrocenyl phosphine-borane: synthesis, structure and evaluation in Rh-catalyzed hydroformylation

The new ambiphilic ligand Ph2P–(1,1′-ferrocenyl)–BMes2, prepared by sequential lithiation/electrophilic trapping of 1,1′-dibromoferrocene, adopts a monomeric structure free of dative P → B and Fe → B interactions. This flexible phosphine-borane and the related o-phenylene bridged system have been evaluated in Rh-catalyzed hydroformylation.

The oxidative addition of a chlorophosphine to Pd0: formation and characterisation of a 42-electron triangulo palladium clusterElectronic supplementary information (ESI) available: General considerations and syntheses. See http://www.rsc.org/suppdata/dt/b4/b408519a/

The reactions that lead to the formation of the 42-electron cluster [PdCl(P(NPr(i)(2))(2))](3) from various sources of the [P(NPr(i)(2))(2)] moiety are investigated, and the structure of the triangulo cluster confirmed by X-ray crystallography.

The ‘one-pot’ syntheses of α,α′-diphosphino-substituted imines: a unique reaction of bulky bis(dialkylamino)chlorophosphines

The reaction between various bis(dialkylamino)chlorophosphines and N-isopropyl-substituted lithium amides afforded bis(α,α′-phosphino)imines in a ‘one-pot’ procedure. These compounds react with sulfur to generate intramolecularly hydrogen-bonded ylide derivatives. The molecular structure of (Pr2iN)2PCH2C(NBut)CH2P(NPri)2 has been determined by X-ray crystallography.

N-Phosphino-amidines and -guanidines: synthesis, structure and P,N-chelate chemistry

The syntheses of the cyclic N-phosphino-amidines and -guanidines Ph2PN(Pri)C(NPri2)N(Pri) ( 1) and Ph2PN(c-Hex)C(R)N(c-Hex) [R = piperazino ( 2), morpholino ( 3), Me ( 4), and Ph ( 5)] are reported. DFT studies have identified the preferred structures for compounds 1-5 with the E-configuration being the most stable form for the N-phosphino-amidines, while the Z-conformation is preferred for the N-phosphino-guanidines something that highlights the potential of such systems to act as kappa2-P,N-chelates. The differences in donor characteristics of 2-5 have been probed through the study of their corresponding P(V) selenide derivatives ( 6-9) and their complexes with the cis-RhCl(CO) (10-12) and cis-PdCl2 (13-17) fragments. In line with the DFT studies both the amidines and guanidines are found to coordinate as kappa2-P,N-chelates, with the latter being moderately weaker donor ligands. The molecular structures of compounds 3 and 4, together with those of the Rh and Pd complexes 10 and 15, respectively, have been determined in the solid state by X-ray crystallography, the latter confirming bidentate kappa2-P,N-chelation.

Synthesis and Reactivity of Group 6 and 10 Complexes of the Bis(dialkylaminophosphanyl)imineiPrN=C[CH2P(NiPr2)2]2

The coordination behaviour of the readily prepared, potentially ambidentate, bis(α,α′-phosphanyl)imine (iPr2N)2PCH2C(=NiPr)CH2P(NiPr2)2 (1, PNP) has been investigated. Treatment of palladium(II), platinum(II), chromium(0), and molybdenum(0) sources with ligand 1 afforded complexes in which 1 was coordinated solely in a bidentate P,N-chelating fashion with a non-coordinating bis(diisopropylamino)phosphanyl-substituted pendant arm. Ligand 1 and complexes [PdCl2(PNP-κ2P,N)] (2) and [Mo(CO)4(PNP-κ2P,N)] (10) were characterised in the solid state by X-ray crystallography. The preparation of cationic PdII derivatives of PNP is discussed.

Coordination chemistry of 2,6-dixylyl-4-phenylphosphabarrelene with selected transition metals

The 2,6-dixylyl-4-phenylphosphabarrelene has been synthesised from the parent phosphinine and its properties as a ligand explored through the preparation and characterisation of the complexes W(CO)(5)(L), Re(CO)(4)(L)Cl, (eta(6)-cymene)RuCl(2)(L), [(eta(5)-Me(3)SiC(5)H(4))Fe(CO)(2)(L)]PF(6), Rh(1,5-COD)(L)Cl, Ir(1,5-COD)(L)Cl, and cis-Pt(L)(2)Cl(2), where L = 4-phenyl-2,10-bis-(2,4-dimethylphenyl)-4H-1,4-ethenophospholine ((x)PB), cymene = 4-isopropyltoluene, eta(5)-Me(3)SiC(5)H(4) = trimethylsilylcyclopentadienyl and 1,5-COD = 1,5-cyclooctadiene. The new complexes were characterised by spectroscopic and analytical techniques and, for [(eta(5)-Me(3)SiC(5)H(4))Fe(CO)(2)(L)]PF(6) and Ru(eta(6)-cymene)(L)Cl(2), by single-crystal X-ray structure determination. The coordination properties of the phosphabarrelene have been established and compared with analogous complexes of triarylphosphines and triarylphosphites. Most spectroscopic and structural indicators suggest that the phosphabarrelene has coordination behaviour similar to that of simple triarylphosphines such as PPh(3).

A tripodal sulfur ligand for the selective ruthenium-catalysed hydrogenation of dimethyl oxalate

The first example of a catalyst utilising a sulfur-based ligand [MeC(CH2SBu)3] for the selective hydrogenation of dimethyl oxalate to methyl glycolate is reported.