Spectroscopic and structural studies of some new organophosphorus compounds

Abstract

The acceptor properties of the alkyl-substituted phosphoranes MePC1(_4) and EtPC1(_4) towards chloride and pyridine ligands have been studied by (^31)P n.m.r. spectroscopy. In PhN0(_2) they react with R(_4) 'NC1 to produce six-coordinate anions, which equilibrate with the parent compound. RPC1(_4) + C1(^-) RPC1(_5)(^-1) (R = Me or Et) With pyridine, MePC1(_4) forms a five-coordinate cation (MePC1(_3)py(^+)Cl(^-)) in solution, whereas EtPC1(_4) gives a white precipitate which analysed as a 1:1 adduct. Cationic species RPC1(_3)L'(^+)C1(^-) are formed with bidentate ligands L' (L' = bipy or phen). RPC1(_3)(^+)SbC1(_6) salts also react with the bidentate pyridines to form six-coordinate complexes, which exist in two isomeric forms. Introduction of more than one alkyl group into the compound R(_n)PC1(_4-n)(^+)Cl(^-) reduces the acceptor properties, however, and no adduct formation has been detected. - CatPBr(_3) decomposes on addition of bromide ion to give catPBr and Br(_3)(^-), while cat(_2)PBr is inert to this ion. cat(_2)PBr and a cationic species with six-coordinate cationic derivatives Pyridine gives a 1:1 molecular adduct with catPBr(_3), whereas bidentate pyridines form cat(_2)PL'(^+) and catPBr(_2)L'(^+) respectively. PhPBr(_4) like catPBr(_3), decomposes in the presence of a bromide ion to give PhPBr(_2) and Br(_3)(^-) , and shows no acceptor properties towards mono- or bidentate pyridines, but the adduct PhPBr(_3)(^+)BBr(_4)(^-) forms six-coordinate complexes with bipy or phen. 31 Several new compounds have been isolated and further characterised by (^31)P.n.m.r. vibrational spectroscopy and elemental analysis. The organophosphorus dicyanides RP (CN)(_2) (R = Me, Et, Ph) add on halide (Cl(^-), Br(^-), I(^-)) or thiocyanate ions to form four coordinate anionic derivatives. The addition of CN(^-) to these cyanides, however, yields organocyanophosphide (I) ions, and cyanogen. Unlike. the cyanides the organophosphorus halides RPC1(_2) (R = Me, t-Bu, Ph) show no tendency to coordinate, although they react with