1978 Volume 51 Issue 12 Pages 3466-3470
To elucidate the ligand conformation and the metal–olefin bonding nature in the binuclear palladium complex of dibenzylideneacetone, Pd2[(C6H5CH=CH)2CO]3, 1H NMR studies have been performed on the deuteriated complexes Pd2[(C6D5CH=CH)2CO]3, Pd2[(C6D5CD=CH)2CO]3, and Pd2[(C6D5CH=CD)2CO]3. Examination of the spectra has revealed that the three dibenzylideneacetone ligands which triply bridge the two Pd atoms are all in the s-cis,trans conformation. The most probable bonding scheme of the three ligands to the two Pd atoms is as follows: one Pd atom is ligated by one s-trans and two s-cis olefinic moieties and hence the other by one s-cis and two s-trans to yield a metal–olefin bonding stronger in the former combination than in the latter. A linear correlation between the couplings and the mean chemical shifts of the trans olefinic protons suggests a dominant role of metal between the couplings and the mean chemical shifts of the trans olefinic protons suggests a dominant role of metal to olefin π-back donation in differentiating the olefinic moieties in their bonding strength to the metal atoms and in retaining the characteristic rigid structure of the complex.
This article cannot obtain the latest cited-by information.