title: Structural, spectroscopic and computational examination of the dative interaction in constrained phosphine-stibines and phosphine-stiboranes.
abstract: A series of phosphine-stibine and phosphine-stiborane peri-substituted acenaphthenes containing all permutations of pentavalent groups -SbCln Ph4-n (5-9), as well as trivalent groups -SbCl2 , -Sb(R)Cl, and -SbPh2 (2-4, R=Ph, Mes), were synthesised and fully characterised by single crystal diffraction and multinuclear NMR spectroscopy. In addition, the bonding in these species was studied by DFT computational methods. The P-Sb dative interactions in both series range from strongly bonding to non-bonding as the Lewis acidity of the Sb acceptor is decreased. In the pentavalent antimony series, a significant change in the P-Sb distance is observed between -SbClPh3 and -SbCl2 Ph2 derivatives 6 and 7, respectively, consistent with a change from a bonding to a non-bonding interaction in response to relatively small modification in Lewis acidity of the acceptor. In the Sb(III) series, two geometric forms are observed. The P-Sb bond length in the SbCl2 derivative 2 is as expected for a normal (rather than a dative) bond. Rather unexpectedly, the phosphine-stiborane complexes 5-9 represent the first examples of the σ(4) P→σ(6) Sb structural motif.
authors.affiliation: EaStChem School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST (UK).
authors.forename: Brian A
authors.initials: BA
authors.lastname: Chalmers
authors.forename: Michael
authors.initials: M
authors.lastname: Bühl
authors.forename: Kasun S
authors.initials: KS
authors.lastname: Athukorala Arachchige
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.forename: Petr
authors.initials: P
authors.lastname: Kilian
keywords: antimony; dative bond; donor-acceptor systems; phosphorus; synthesis