The synthesis and metal complexes of some unusual phosphines
The high temperature and pressure synthesis of chlorophosphines from an alkene, white phosphorus and phosphorus trichloride yielded both mono- and diphosphine products. Chain and cyclic alkenes, dienes and terpenes were used as substrates forming chain, ring and bicyclic mono- and diphosphines. Many novel, even unique, chlorophosphines were prepared in good yield and characterised using (^31)P and (^13)C NMR, mass spectroscopy and elemental analysis. Simple alkenes readily reacted forming mono- and 1,2-diphosphines. However 1,5-cyclooctadiene formed a 1,4-addition product after double bond conjugation. Butadiene dimerised prior to reaction, generating either a 2,2'-diphospholane or a 1,4-bridged phosphabicyclic alkane in addition to 1,2- and 1,4-diphosphines. Terpenoid dichlorophosphines were prepared but could not be isolated or characterised, because the substrate isomerised under the reaction conditions generating many similar products. Aromatic rings did not react, although the exocyclic double bond of styrene did undergo reaction. Chiral phosphines were readily produced from unsymmetric pro-chiral, alkenes. Chlorophosphines are versatile precursors and, using standard organophosphorus techniques, were readily converted to phosphines, phosphites and other organophosphorus ligands suitable for chelation. Grignard reagents were used to prepare dimethyl derivatives, alcohols reacted with dichlorophosphines producing diethyl-, dimenthyl- or 1,4-butylphosphite derivatives, Piperazine also reacted although the products could not be fully characterised. Electronic properties (^Mn)χ) of the phosphines in manganese carbonyl halide derivatives were measured as a function of the A(_1)carbonyl stretching frequency. Substituent electronegativity was the most important factor in determining the π-acidity. Some dichloropalladium complexes were studied using 3ip NMR, although phosphine impurities complicated spectral interpretation. Iron and molybdenum hydrides reacted with dichlorophosphines to produce some unusual metal-phosphine compounds.