Synthesis, Characterization, and Reactivity of 1,1‘-Bis(diphenylphosphino)osmocene: Palladium(II) Complexes and Their Use as Catalysts in the Methoxycarbonylation of Olefins

Synthesis of disubstituted furans catalysed by [(AuCl)2(μ-bis(phosphino)metallocene)] and Na[BArF24]

Two new gold compounds with bis(phosphino)metallocene ligands were prepared and characterized by NMR and X-ray crystallography. These and related compounds are catalysts in formation of disubstituted furans from terminal alkynes and pyridine-N-oxide.

Ferrocenylmethylphosphanes and the Alpha Process for Methoxycarbonylation: The Original Story

The Lucite Alpha process is the predominant technology for the preparation of acrylics. This two-stage process involves the palladium-catalysed formation of methyl propanoate from ethene, CO, and methanol, followed by the oxidative formylation of methyl propanoate into methyl methacrylate. A range of bis-1,2-disubstituted aminomethylferrocenes has been prepared and characterised. These complexes serve as precursors to a variety of bulky ferrocenylmethyldiphosphanes that, in turn, function as ligands in the palladium-catalysed process. We describe the crystal structures of five ligand precursors and provide a rationale for their design. In situ catalyst testing on palladium complexes derived from ferrocenylphosphanes demonstrates that these are highly selective (>99.5%) catalysts for the formation of methyl propanoate from ethene, CO, and methanol and have turnover numbers exceeding 50,000. This article credits those researchers who worked on this project in the early days, who received little or no credit for their achievements and endeavours.

Diphosphanylmetallocenes of Main-Group Elements

Several 1,1'-diphosphanyl-substituted metallocenes of magnesium (magnesocenes) were synthesized, structurally characterized, and their reactivity and coordination chemistry were investigated. Transmetalation of these magnesocenes gives access to group 14 metallocenes (tetrelocenes), as well as to group 15 stibonocenes. These s- and p-block metallocenes represent a novel class of bis(phosphanyl) ligands, exhibiting Lewis-amphiphilic character. Their coordination chemistry towards different transition-metal and main-group fragments was investigated and different complexes are presented.

Catalytic Phosphite Hydrolysis under Neutral Reaction Conditions

Cationic phosphametallocene-based platinum(II) aqua complexes were used as efficient precatalysts for the hydrolysis of aromatic and aliphatic tertiary phosphites under neutral reaction conditions at room temperature, leading to the selective cleavage of one P-O bond of the phosphite. NMR labeling experiments combined with stoichiometric model reactions and theoretical density functional theory calculations, performed with the appropriate model compounds, shed light on the operative catalytic cycle, which comprises intramolecular water molecule transfer to the cis-coordinated phosphite molecule.

Carbonylation of ethene catalysed by Pd(II)-phosphine complexes

This review deals with olefin carbonylation catalysed by Pd(II)-phosphine complexes in protic solvents. In particular, the results obtained in the carbonylation with ethene are reviewed. After a short description of the basic concepts relevant to this catalysis, the review treats in greater details the influence of the bite angle, skeletal rigidity, electronic and steric bulk properties of the ligand on the formation of the products, which range from high molecular weight perfectly alternating polyketones to methyl propanoate. It is shown that the steric bulk plays a major role in directing the selectivity. Particular emphasis is given to the factors governing the very active and selective catalysis to methyl propanoate, including the mechanism of the catalytic cycles with diphosphine- and monophosphine-catalysts. A brief note on the synthesis of methyl propanoate using a “Lucite” type catalyst in ionic liquids is also illustrated. A chapter is dedicated to the carbonylation of olefins in aqueous reaction media. The nonalternating CO-ethene copolymerization is also treated.

Reversible CO exchange at platinum(0). An example of similar complex properties produced by ligands with very different stereoelectronic characteristics

The electron-rich, bulky diphosphines La and Lb support three- and four-coordinate carbonylplatinum(0) complexes, as does the electron-poor diphosphine Lf.

Metal-catalyzed synthesis of alternating copolymers

The creation of polymers with a high degree of sequence and/or stereocontrol represents an exciting frontier in materials science. In order to obtain alternating polymers, coordination polymerization using well-defined metal complexes has played a leading role in the last two decades. In the following paper, we will describe selected published efforts to achieve these research goals using discrete, structurally well-characterized metal complexes.