Robust and Operationally Simple Synthesis of Poly(bis(2,2,2-trifluoroethoxy) phosphazene) with Controlled Molecular Weight, Low PDI, and High Conversion.

Synthetically straightforward conditions have been developed for the preparation of poly(bis 2,2,2-trifluoroethoxy)phosphazene with low PDI (<1.15) at high conversion (75-99%) and on a multigram scale. A combination of 31P NMR and GPC analyses demonstrate that molecular weight increases linearly as a function of monomer consumption, exhibiting first order kinetics with respect to monomer concentration up to high monomer conversion. Thus, the molecular weight can be controlled by varying the initiator (H2O) to monomer ratio.

Coordination chemistry with phosphine and phosphine oxide-substituted hydroxyferrocenes.

New unsymmetrical hydroxyferrocenes were synthesised from dibromoferrocene. The oxygen heteroatom was introduced via lithiation and quenching with bis-trimethylsilylperoxide followed by hydrolysis to unmask the hydroxyl functionality. The coordination chemistry of 1'-(diphenylphosphino)-1-hydroxyferrocene 2 was explored with palladium and rhodium precursors. A dinuclear palladium methyl complex with bridging ferrocenyloxo groups was obtained from the reaction between 2 and (cyclooctadiene)methylchloropalladium(II). With tetracarbonyldichlorodirhodium(I), two complexes were isolated. The major product was a bis ligand cis phosphine ligated complex with one ligand bound in a chelating mode and one with a pendant hydroxyl group. A minor product was crystallographically characterised as a dinuclear ferrocenyloxo-bridged rhodium carbonyl complex. The coordination chemistry of 2 and the corresponding phosphine oxide 3 was examined with group 4 metals and the resulting complexes examined as ethylene polymerisation catalysts. The ligands were found to bind in either a chelating fashion or with pendant phosphine donors. In all cases, low to moderately active ethylene polymerisation catalysts were found. The catalysts were very unstable and catalyst residues were observed in the isolated polymer indicating a short catalyst lifetime.

New S/O-substituted ferrocenediyl ligands and their metal complexes.

New unsymmetrical S/O 1,1'-disubstituted ferrocenediyl ethers and hydroxides have been synthesised. The coordination chemistry of 1-(methylsulfanyl)-1'-(methoxy)ferrocene has been investigated with palladium(II) and platinum(II) precursors. With palladium(II), a bis-mu-chloro-bridged dimeric complex was obtained with the ligand bound solely through the thioether donor group. With platinum(II), a bis-ligand trans-sulfur ligated complex was obtained and structurally characterised.

Novel unsymmetrical P/O substituted ferrocene ligands and the first structurally characterised hydroxyferrocene derivative.

Two new unsymmetrical 1'-substituted hydroxyferrocene ligands featuring either phosphine or phosphine oxide substituents have been synthesised and the phosphine oxide derivative has been structurally characterised. A nickel complex of the hydroxyl/phosphine ligand has been formed, along with preliminary evaluation of the complex for catalysis of ethylene polymerisation.

The syntheses and catalytic applications of unsymmetrical ferrocene ligands.

Interest in the chemistry of ferrocene remains intense, largely due to applications within catalysis. New synthetic routes to unsymmetrical ferrocene ligands have provided another facet to this area, as substituents can be designed to be electronically- and/or sterically-distinct in order to affect the environment around the catalytically-active metal centre. This critical review provides a concise summary of the synthetic routes that have been applied to the synthesis of unsymmetrical ferrocene ligands, along with a systematic survey of the applications of these ligands in homogeneous catalysis. The aim is to help the reader select a suitable ferrocenediyl ligand for a particular synthetic application, and in the synthesis of ligands that require particular structural and/or electronic features.