H. Barucki et al., Characterising secondary bonding interactions within triaryl organoantimony(V) and organobismuth(V) complexes, J CHEM S DA, (14), 2000, pp. 2319-2325
Citations number
53
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
The thermodynamically preferred conformations of the five-co-ordinate trigo
nal-bipyramidal complexes SbPh3Cl2 1 and BiPh3Cl2 2, determined via van der
Waals energy calculations, have been found to be in good agreement with th
e corresponding correlated propeller arrangements which are observed in the
solid state. However, similar calculations upon the corresponding diesters
SbPh3(O2CR)(2) 3 and BiPh3(O2CR)(2) 4 [R = C(OH)Ph-2 a or C6H4OH-o b] were
at variance with the solid state, thereby indicating the participation of
stabilising secondary bonding interactions between the metal centre and the
carbonyl oxygen atom of the ester moiety. In accord with current Lewis aci
d-base bonding models, a strong correlation was found to exist between the
pK(a) of the parent acid and the magnitude of the M ... O=C interaction. Th
e complexes 3a,3b and 4a,4b were prepared in order to probe the effect of s
trong intramolecular hydrogen bonding upon the ability of ester ligands to
stabilise sterically disfavoured conformations via sigma(nb) donation. Sing
le crystal X-ray analyses of 3a,3b and 4a demonstrate that although signifi
cant attenuation of the M ... O=C interaction is achieved via strong intram
olecular hydrogen bonding, sterically disfavoured arrangements predominate
in the solid state.