三苯膦-铂(Ⅱ)络合物的质子核磁共振研究(Ⅰ)

过渡金属离子的d-电子特性,使得它们的络合物可以在很多有机合成反应中起催化作用,含三苯磷配体的反式铂氢络合物就是一种稳定的、广泛应用的催化剂^1.2.3.4.]。为此,本工作合成了反式-PtHXL₂],L=PPh₃,X=Cl^-、Br^-、I^-、NO₃^-、NO₂^-、NCS^-六种铂络合物,并测定了其¹H-NMR谱。实验获得该络合物系列中,与铂(Ⅱ)相连的质子在高场具有较大的化学位移,即δ_H=-12~-24ppm和很大的铂-氢偶合常数即J_pt-H=900-1400Hz,以及磷氢偶合常数即J_p-H≈15Hz。此外,还研究了配体对铂-氢的¹H化学位移及铂-氢偶合常数;铂-氢键长对铂-氢的¹H化学位移的影响,并找出了一定的规律性。从而得到了络合物的顺反异构,键合异构及电子密度分布的有关信息。关于铂络合物的核磁共振研究,虽有过报道^5.6],但配体为三苯膦的反式-PtH(PPh³)₂]系列络合物NMR研究,尚未见报道。

1H-NMR STUDIES OF TRIPHENYL PHOSHINE-PLATINUM(Ⅱ) COMPLEXES(Ⅰ)

A Series of platipum (Ⅱ) complexes of the transPHX (PPh₃)₂], where anionic ligand(X)=NO₃^-、NO₂^-、NCS^-、Cl^-、Br^-、and I^-, have been prepared. ¹H-NMR studies of these complexes have been made. The ¹H-NMR spectra of these platincnm complexes obtained show a very large hige-field ¹H chemical shift(δ_H) in the range of-12 to-24 ppm. The coupling constants (J_pt-H) of platinum hydrogen are also large,and range 900-1400Hz, J_P-H of phosphines are about 15Hz. The effects of Ligands (X), (L) on the chemical shift and coupling constant, as well as the effect of the length of platinum(Ⅱ) hydrogen bond on the chemical shemical shift (δ_H)were studies. A linear relationship between the electronegativity of there anionic ligane (X) and ¹H chemical shift (δ_H) has been correlated.