Metal−Metal Bonded Homo- and Heterobimetallic Compounds of Pt(I) and Pd(I) Supported by a Bridging-N,P:N‘,P‘ Moiety of a Potentially Hexadentate Ligand

Coordination of bis(azol-1-yl)methane-based bisphosphines towards RuII, RhI, PdII and PtII: synthesis, structural and catalytic studies

This paper describes the transition metal chemistry of three bis(X-diphenylphosphino-azol-1-yl)-based bisphosphines: bis(2-Ph₂P-imidazol-1-yl)methane (1), bis(5-Ph₂P-pyrazol-1-yl)methane (2) and bis(5-Ph₂P-1,2,4-triazol-1-yl)methane (3). These show versatility in their coordination behaviour.

Dinuclear copper complexes: coordination of Group 14 heteroborates

The dinuclear copper(i) complex [Cu₂(μ-dmapm)(CH₃CN)₂][BF₄]₂ was reacted with Group 14 heteroborates. Four different coordination motives have been characterized.

Various coordination modes of the bis(di(o-N,N-dimethylanilinyl)phosphino)methane ligand in mononuclear and binuclear complexes of group 8 and group 9 metals

The synthesis and characterization of a series of compounds involving the bis(di(o-N,N-dimethylanilinyl)phosphino)methane (dmapm) ligand are described. The mononuclear complexes [MCl(CO)(P,N-dmapm)] (M = Rh, Ir) have a square-planar geometry in which the dmapm ligand chelates via a phosphine functionality and an adjacent amino group. The carbonyl ligand lies opposite the amine, while the chloro ligand is trans to the phosphine. The related complex [RhI(CO)(P,N-dmapm)] has also been prepared. All compounds are highly fluxional by at least three independent processes, as discussed for the rhodium-chloro species. A diiridium complex, [Ir(2)Cl2(CO)2(P,N,P',N'-dmapm)], and the closely related rhodium/iridium analogue, [RhIrCl2(CO)2(P,N,P',N'-dmapm)], have been prepared in which the metals are bridged by the diphosphine group while an amino group at each end of the diphosphine is also coordinating to each metal on opposite faces of the MIrP2 plane (M = Ir or Rh). For the Ir2 species, the carbonyl and chloro groups are again shown to be opposite the amine and phosphine functionalites, respectively. The mononuclear complex [Ru(CO)3(P,P'-dmapm)] has also been prepared. In contrast to the mononuclear species of rhodium and iridium, the dmapm group chelates the ruthenium center through both phosphorus atoms, occupying one axial and one equatorial site of Ru in a distorted trigonal bipyramidal geometry. Reaction of this Ru species with 1/2 equiv of the complexes [RhClL2]2 (L2 = COD, (C2H4)2, (CO)2) yields the unstable Rh/Ru product [RhRuCl(CO)3(P,N,P',N'-dmapm)].

Palladium(II) complexes of bis(phosphine)monooxide and bis(phosphine)monosulphide ligands bearing o-N,N-dimethylanilinyl substituents

Palladium(II) complexes of bis(phosphine)monooxide and bis(phosphine)monosulphide ligands with the general formula Ar2P(CH2)nP(E)Ar2 are described (n = 1 (dmapmE), E = O, S; n = 2 (dmapeE), E = O; Ar = o-N,N-dimethylanilinyl). The precursor, PdCl2(dmapm), which exists in solution as an equilibrium mixture of the P,P- and P,N-ligated isomers, reacts with peroxides to form PdCl2(P,N-dmapmO) and with sulphur to give [PdCl(P,N,S-dmapmS)]Cl, probably by direct oxidation of the "dangling" P atom of the P,N-isomer. PdCl2(dmape), which exists in solution as a mixture of PdCl2(P,P-dmape) and [PdCl(P,P,N-dmape)]Cl, reacts with hydroxide in H2O–CH2Cl2 under argon to give the face-to-face Pd(II)2 complex containing the cation [Pd2Cl2(µ-P,N:O-dmapeO)2]2+, which was isolated and crystallographically characterized as the PF6 salt. The remarkable structure, consisting of two face-to-face Pd(II) square planes in a head-to-tail orientation, reveals a 12-membered ring containing the two non-bonded metal centres (Pd—Pd = 4.873(2) Å). The dmapmS complex shows marginal activity as a catalyst for the hydration of maleic to malic acid.Key words: phosphine, phosphine oxide, phosphine sulphide, palladium.

Platinum(II) and Palladium(II) Complexes of Bisphosphine Ligands Bearing o-N,N-Dimethylanilinyl Substituents: A Hint of Catalytic Olefin Hydration

Platinum(II) and palladium(II) complexes of the potentially hexadentate P,N-donor ligand family Ar2P-X-PAr2 (X = (CH2)2 [dmape], cyclic-C5H8 [dmapcp]; Ar = o-N,N-dimethylanilinyl) are described. In CH2Cl2, the dmape complexes exist as equilibrium mixtures of MCl2(P,P'-dmape) and [MCl(P,P',N-dmape)]Cl isomers (M = Pd, Pt), governed by deltaH(o) = -19 +/- 4 kJ mol(-1) and deltaS(o) = -100 +/- 30 J mol(-1) K(-1) for M = Pt, and deltaH(o) = -11 +/- 7 kJ mol(-1) and deltaS(o) = -60 +/- 20 J mol(-1) K(-1) for M = Pd. The water-soluble dmapcp complexes exist solely in the [MCl(P,P',N-dmapcp)]Cl form, but the free and coordinated anilinyl rings in these complexes are in slow diastereoselective exchange. X-ray crystal structures for MCl2(P,P'-dmape) (M = Pd, Pt), and the [PdCl(P,P',N-dmape)]+ and [PtCl(P,P',N-dmapcp)]+ cations, are presented. Some of the complexes show marginal activity in water for the catalyzed hydration of maleic to malic acid, giving about 6-7% conversion in 24 h at 100 degrees C and substrate:catalyst loadings of 100:1. Attempts to synthesize a PdCl(P,P',N-dmapm)+ species led instead to isolation of [Pd(mu-Cl)(P,P'-dmapm)]2[PF6]2 (dmapm = Ar2PCH2Ar2).