Synthesis of 1,3-azaphosphol-2-ones. Crystal and molecular structures of [SP-4-2]-dichlorobis(3-phenyl-1,3-dihydrobenzo[1,3]azaphosphol-2-one-P)p alladium(II) and its chloro(methyl)platinum(II) analogue

摘要

Reaction of secondary phosphine (+/-)-(2-aminophenyl)phenylphosphine, (+/-)-app, with PCl5 in toluene gives the hydrochloride salt of the expected chlorophosphine (+/-)-(2-aminophenyl)chlorophenylphosphine, (+/-)-acpp center dot HCl, however, this is not the case with triphosgene. Rather the first example of a 1,3-azaphosphol-2-one is isolated, viz. (+/-)-3-phenyl-1,3-dihydrobenzo[1,3]azaphosphol-2-one, (+/-)-pbap. The hydrochloride salt (+/-)-acpp. HCl readily reacts with excess vinyl-, 2-methylphenyl- or 2-methoxyphenyl magnesium bromide to give the corresponding tertiary phosphines (+/-)-(2-H2NC6H4)PPhR (where R = CH=CH2, 2-C6H4Me or 2-C6H4OMe). Hydrophosphination of the vinyl substituted tertiary phosphine with (+/-)-app in the presence of KOBut provides a synthetic route to the elusive P2N2 quadridentate ligand (R-P*,R-P*)- and (R-P*,S-P*)-(CH2)(2)(PPhC6H4NH2-2)(2), albeit in low yield. The azaphospholone (+/-)-pbap can be readily deprotonated with KOBut in thf and subsequently alkylated with methyl iodide or benzyl bromide to give the analogous N-methyl or N-benzyl derivatives. Alkylation with 1,3-dibromopropane gives the bis(azaphospholone) (R-P*, R-P*)- and (R-P*, S-P*)-1,3-bis[1-{3-phenyl-1,3-dihydrobenzo[1,3]azaphosphol-2-one}]propan e. The latter and the N-methyl substituted azaphospholone can also be synthesised by the reaction of the corresponding secondary phosphine, viz. (R-P*, R-P*)-and (R-P*, S-P*)-(CH2)(3)(NHC6H4PHPh-2)(2) and (+/-)-(2-methylaminophenyl)phenylphosphine, with triphosgene. All three azaphospholones react with [PtClMe(1,5-cyclooctadiene)] in thf to give complexes of the type cis-[PtClMeL2] in which ligand L is coordinated via the P atom of the azaphospholones. The ligand (+/-)-pbap has also been complexed to palladium(II) via the reaction with Li-2[PdCl4] in methanol to give cis-[PdCl2{(+/-)-pbap}(2)]. The structures of cis-[PtClMe{(+/-)-pbap}(2)] and cis-[PdCl2{(+/-)-pbap}(2)] have been confirmed by X-ray analysis.