title: Intramolecular phosphine-phosphine donor-acceptor complexes.
abstract: The reaction of 5-diphenoxyphosphanyl-6-diisopropylphosphinoacenaphthene 12 with chlorotrimethylsilane unexpectedly gave a phosphonium-phosphine compound 13, containing the structural motif of four phosphorus atoms connected in a chain. To explain the mechanism of this complex transformation, a proposed intermediate 5-dichlorophosphino-6-diisopropylphosphinoacenaphthene 14 was synthesized by an alternative method. The two (formally) phosphine environments in 14 form an intramolecular donor-acceptor (phosphonium-phosphoranide) complex, stable at room temperature in the solid state and as a solution in certain solvents. A (31)P NMR mechanistic study showed that, despite the presence of a rigid acenaphthene backbone, 14 is unstable in the presence of nucleophiles and disproportionates into 13 and other phosphorus containing products. Both 13 and 14 have been crystallographically characterized.
authors.affiliation: School of Chemistry, EastCHEM, University of St Andrews, St Andrews, Fife KY16 9ST, UK.
authors.forename: Piotr
authors.initials: P
authors.lastname: Wawrzyniak
authors.forename: Amy L
authors.initials: AL
authors.lastname: Fuller
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.forename: Petr
authors.initials: P
authors.lastname: Kilian