title: Hypervalent silicon compounds by coordination of diphosphine-silanes to gold.
abstract: Coordination of ambiphilic diphosphine-silane ligands [o-(iPr(2)P)C(6)H(4)](2)Si(R)F (R=F, Ph, Me) to AuCl affords pentacoordinate neutral silicon compounds in which the metal atom acts as a Lewis base. X-ray diffraction analyses, NMR spectroscopy, and DFT calculations substantiate the presence of Au→Si interactions in these complexes, which result in trigonal-bipyramidal geometries around silicon. The presence of a single electron-withdrawing fluorine atom is sufficient to observe coordination of the silane as a σ-acceptor ligand, provided it is positioned trans to gold. The nature of the second substituent at silicon (R=F, Ph, Me) has very little influence on the magnitude of the Au→Si interaction, in marked contrast to N→Si adducts. According to variable-temperature and 2D EXSY NMR experiments, the apical/equatorial positions around silicon exchange in the slow regime of the NMR timescale. The two forms, with the fluorine atom in trans or cis position to gold, were characterized spectroscopically and the activation barrier for their interconversion was estimated. The bonding and relative stability of the two isomeric structures were assessed by DFT calculations.
authors.affiliation: University of Toulouse, UPS, LHFA, CNRS, LHFA UMR 5069, 118 route de Narbonne, 31062 Toulouse, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Gualco
authors.forename: Maxime
authors.initials: M
authors.lastname: Mercy
authors.forename: Sonia
authors.initials: S
authors.lastname: Ladeira
authors.forename: Yannick
authors.initials: Y
authors.lastname: Coppel
authors.forename: Laurent
authors.initials: L
authors.lastname: Maron
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Amgoune
authors.forename: Didier
authors.initials: D
authors.lastname: Bourissou