title: 3H-benzophosphepine complexes: versatile phosphinidene precursors.
abstract: The synthesis of a variety of benzophosphepine complexes [R = Ph, t-Bu, Me; ML(n )()= W(CO)(5), Mo(CO)(5), Cr(CO)(5), Mn(CO)(2)Cp] by two successive hydrophosphinations of 1,2-diethynylbenzene is discussed in detail. The first hydrophosphination step proceeds at ambient temperature without additional promoters, and subsequent addition of base allows full conversion to benzophosphepines. Novel benzeno-1,4-diphosphinanes were isolated as side products. The benzophosphepine complexes themselves serve as convenient phosphinidene precursors at elevated, substituent-dependent temperatures (>55 degrees C). Kinetic and computational analyses support the proposal that the phosphepine-phosphanorcaradiene isomerization is the rate-determining step. In the absence of substrate, addition of the transient phosphinidene to another benzophosphepine molecule is observed, and addition to 1,2-diethynylbenzene furnishes a delicate bidentate diphosphirene complex.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: Mark L G
authors.initials: ML
authors.lastname: Borst
authors.forename: Rosa E
authors.initials: RE
authors.lastname: Bulo
authors.forename: Danièle J
authors.initials: DJ
authors.lastname: Gibney
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Alem
authors.forename: Frans J J
authors.initials: FJ
authors.lastname: de Kanter
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Ehlers
authors.forename: Marius
authors.initials: M
authors.lastname: Schakel
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Koop
authors.initials: K
authors.lastname: Lammertsma