The new phosphinite and phosphonite complexes (1–8) are very efficient catalysts for the methoxycarbonylation of iodobenzene and Heck cross-coupling of bromobenzene with butyl acrylate. High catalytic activity of these complexes can be explained by their in situ transformations during the reaction, stimulated by the presence of water, acid (HCl) or base (NEt3). Hydrolysis of phosphinite palladium complexes of the form trans-PdCl2[PPh2(OR)]2 (R = C6F52, tBu 3, or O-menthyl 4) results in the formation of the dimeric complex [μ-ClPd(PPh2OH)(PPh2O)]25, which is deprotonated by NEt3, producing a polymeric complex of formula [Pd(P(O)PPh2)2]n8. The reverse reaction, protonolysis of 8 with HCl, leads back to 5 and the monomeric complex 5a. The phosphinite complex PdCl2[PPh2(OBu)]21 with a more lipophilic ligand, PPh2(OBu), does not undergo hydrolysis under the same conditions. In the reaction of PdCl2(cod) with P(OPh)2(OH), the new dimer [μ-ClPd(P(OPh)2OH)(P(OPh)2O)]26 was obtained, whereas reaction of Pd(OAc)2 with P(OPh)2(OH) leads to the polymeric complex [Pd[P(O)(OPh)2]2]n7. Protonolysis of 7 with HCl results in the formation of 6.
新的膦类和膦
胺类的配合物(1-8)是
碘苯的甲氧基酰化反应和
溴苯与丁基
丙烯酸酯进行Heck交叉偶联反应的高效催化剂。这些配合物的高催化活性可以通过它们在反应过程中发生的原位转化来解释,这种转化受到
水、酸(HCl)或碱(NEt3)存在的刺激。形式为trans-PdCl2[PPh2(OR)]2的膦类
钯配合物(R = C6F52、tBu 3或O-薄荷基4)的
水解会形成二聚配合物[μ-ClPd(PPh2OH)(PPh2O)]25,该配合物被NEt3去质子化,生成聚合物[ечноPd(P(O)PPh2)2]n8。逆反应,即用HCl进行的8的质子解离反应,会返回到5和单体配合物5a。含有更亲脂性
配体PPh2(OBu)的膦类配合物PdCl2[PPh2(OBu)]21在相同条件下不发生
水解。在PdCl2(cod)与P(OPh)2(OH)的反应中,得到新的二聚体[μ-ClPd(P(OPh)2OH)(P(OPh)2O)]26,而Pd(OAc)2与P(OPh)2(OH)的反应则导致聚合物配合物[Pd[P(O)(OPh)2]2]n7的形成。用HCl进行7的质子解离反应会形成6。