title: Si=P double bonds: experimental and theoretical study of an NHC-stabilized phosphasilenylidene.
abstract: An experimental and theoretical study of the first compound featuring a Si=P bond to a two-coordinate silicon atom is reported. The NHC-stabilized phosphasilenylidene (IDipp)Si=PMes* (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, Mes*=2,4,6-tBu3 C6 H2 ) was prepared by SiMe3 Cl elimination from SiCl2 (IDipp) and LiP(Mes*)SiMe3 and characterized by X-ray crystallography, NMR spectroscopy, cyclic voltammetry, and UV/Vis spectroscopy. It has a planar trans-bent geometry with a short Si=P distance of 2.1188(7)Å and acute bonding angles at Si (96.90(6)°) and P (95.38(6)°). The bonding parameters indicate the presence of a Si=P bond with a lone electron pair of high s-character at Si and P, in agreement with natural bond orbital (NBO) analysis. Comparative cyclic voltammetric and UV/Vis spectroscopic experiments of this compound, the disilicon(0) compound (IDipp)Si=Si(IDipp), and the diphosphene Mes*P=PMes* reveal, in combination with quantum chemical calculations, the isolobal relationship of the three double-bond systems.
authors.affiliation: Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn (Germany).
authors.forename: Daniel
authors.initials: D
authors.lastname: Geiß
authors.forename: Marius I
authors.initials: MI
authors.lastname: Arz
authors.forename: Martin
authors.initials: M
authors.lastname: Straßmann
authors.forename: Gregor
authors.initials: G
authors.lastname: Schnakenburg
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Filippou
keywords: isolobal relationship; main-group elements; multiple bonds; phosphorus; silicon