Inorganic Chemistry, Vol.49, No.9, 4307-4312, 2010
Effect of Pnictogen Ligand Substitution on a Tripalladium Ditropylium Core
A combination of multinuclei NMR, UV-vis spectroscopy, and single crystal X-ray diffraction was used to characterize a new series of tripalladium ditropylium sandwich complexes [Pd3Tr2(E)(3)][BF4](2) (E = PPh3, AsPh3, and SbPh3 and PEt3) Ligand substitution leads to a systematic shift of the H-1 and C-13 NMR tropylium resonances and is correlated with the electron donating properties of the substituent group. Replacement of the ligand increases the palladium-pnictogen bond length in the order P < As < Sb; however, this only slightly alters the internal Pd-Pd bond lengths, supporting the hypothesis that there are only weak Pd-Pd bonding interactions.