106870-56-8Relevant articles and documents
Structural, spectroscopic and computational examination of the dative interaction in constrained phosphine-stibines and phosphine-stiboranes
Chalmers, Brian A.,Bühl, Michael,Athukorala Arachchige, Kasun S.,Slawin, Alexandra M. Z.,Kilian, Petr
, p. 7520 - 7531 (2015)
Abstract A series of phosphine-stibine and phosphine-stiborane peri-substituted acenaphthenes containing all permutations of pentavalent groups -SbClnPh4-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 -SbCl2Ph2 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 SbIII 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 σ4P→σ6Sb structural motif. A complex situation: The strength of a dative phosphine-stiborane (P-Sb) interaction increases with stepwise replacement of phenyl groups on antimony atom with chloride groups. As the Lewis acidity is increased in regular steps (see figure), essentially linear response is observed initially, however then a sudden change in the P-Sb distance takes place during one particular step. This is consistent with a sudden switch from a non-bonding to a bonding interaction, that is, a discrete rather than continuum response.
