Cage Phosphinites: Ligands for Efficient Nickel-Catalyzed Hydrocyanation of 3-Pentenenitrile

The cage monophosphinites CgPOR {where CgP = 6-phospha-2,4,8-trioxa-adamantane and R = C6H5 (La); 2-C6H4CH3 (Lb); 2,4,6-C6H2(CH3)3 (Lc); 2,4-C6H3tBu2 (Ld); CH3 (Le); CH2CF3 (Lf)} and diphosphinites CgPZPCg {where ZH2 = 2,2′-biphenol (Lg) or 1,2-benzenedimethanol (Lh)} have been made from CgPBr and the corresponding alcohol or phenol. The cage phosphinites are remarkably stable to water. All the ligands La−h have been tested for nickel(0)-catalyzed hydrocyanation of 3-pentenenitrile in the presence of Lewis acids (ZnCl2, Ph2BOBPh2, or iBu2AlOAliBu2), and tentative structure−activity relationships are suggested. The hydrocyanation activities obtained with catalysts derived from monophosphinite Lf (with iBu2AlOAliBu2) and diphosphinite Lh (with ZnCl2) are comparable with the commercial catalyst based on P(OTol)3. The complexes trans-[PtCl2(L)2] where L = La (1a), Le (1e), and Lf (1f) and the chelate cis-[PtCl2(Lh)] (1h) are reported. From the νCO values for the complexes trans-[RhCl(CO)(La−f)2] (2a−f), it is concluded that ligand Lf is the most phosphite-like of the monophosphinites. Treatment of [Ni(cod)2] (cod = 1,5-cyclo-octadiene) with Lh leads to a mixture of products, one of which was characterized as the binuclear [Ni2(Lh)2(μ-cod)] (3h). The crystal structures of Lh, 1a, 1e, 1f, 1h·2CH2Cl2, and 3h·3C6H5CH3 are reported.

笼状单亚膦酸酯（cage monophosphinites）CgPOR {其中CgP代表6-磷杂-2,4,8-三氧杂金刚烷（6-phospha-2,4,8-trioxa-adamantane），R分别为C6H5（对应配体La）、2-C6H4CH3（对应配体Lb）、2,4,6-C6H2(CH3)3（对应配体Lc）、2,4-C6H3tBu2（对应配体Ld）、CH3（对应配体Le）、CH2CF3（对应配体Lf）}，以及双亚膦酸酯CgPZPCg {其中ZH2为2,2′-联苯酚（2,2′-biphenol，对应配体Lg）或1,2-苯二甲醇（1,2-benzenedimethanol，对应配体Lh）}，均可由CgPBr与相应的醇或苯酚制备得到。该类笼状亚膦酸酯对水具有优异的稳定性。所有配体La~h均被应用于零价镍（nickel(0)）催化的3-戊烯腈氢氰化反应测试，测试体系中添加了路易斯酸（Lewis acids）：ZnCl2、Ph2BOBPh2或iBu2AlOAliBu2，研究初步提出了该类配体的结构-活性关联规律。由单亚膦酸酯Lf（搭配助剂iBu2AlOAliBu2）与双亚膦酸酯Lh（搭配助剂ZnCl2）制备得到的催化剂，其氢氰化活性可与商业化的P(OTol)3基催化剂相媲美。本文报道了配合物trans-[PtCl2(L)2]（其中L分别为La（对应配合物1a）、Le（对应配合物1e）和Lf（对应配合物1f）），以及螯合型cis-[PtCl2(Lh)]（对应配合物1h）。通过对配合物trans-[RhCl(CO)(La−f)2]（2a~2f）的νCO（羰基伸缩振动频率）数据进行分析，可得出结论：配体Lf是所有单亚膦酸酯中最接近亚磷酸酯的配体。将[Ni(cod)2]（其中cod为1,5-环辛二烯，1,5-cyclo-octadiene）与配体Lh进行反应，得到了产物混合物，其中一种产物被表征为双核配合物[Ni2(Lh)2(μ-cod)]（对应配合物3h）。本文同时报道了配体Lh、配合物1a、1e、1f、1h·2CH2Cl2以及3h·3C6H5CH3的晶体结构。