^(13)C-NMR研究联吡啶钯系列配合物的电荷分布

Study on Charge Distribution for Palladium (Ⅱ) Complexes with 2,2 Bipyridine and 4,4 Dimethyl 2,2 Bipyridine by 13 C NMR

测定并归属了联吡啶及其衍生物与钯形成的几种配合物的１３Ｃ－ＮＭＲ谱．配合物与自由配体的化学位移差值（ＣＩＳ）能够从微观结构上反映金属离子与配体的相互作用细节．在所研究的配合物中，杂原子Ｎ与金属配位后，π－效应使γ－位碳的电荷密度降低，而金属离子对配体的ｄ－π＊反馈成键作用使α－位碳的电荷密度得到明显补偿．

C NMR spectra of the palladium(Ⅱ) complexes containing the bidentate ligands, 2,2 bipyridine (bpy) and 4,4 dimethyl 2,2 bipyridine (dmbpy),are reported and compared to those of the corresponding free ligands.Coordination induced shifts (CIS,δ complexed δ free ) are discussed on the bases of the various effects. In these complexes,π effect makes the electron densities of γ carbons decrease,while d π * backdonation to the ligand induces a slight increase in the electron density at α carbons.