The reaction of secondary phosphines HPR2 (R = Ph, Cy) with pyrrole-2-aldehydes gives a new family of 2-phosphorylmethyl-1H-pyrroles as potentially chelating mono-anionic ligands. The reaction with Ti(NMe2)4 affords octahedral Ti(NMe2)2NC4H2(4-R′)CH2P(O)R2}2 (R′ = H, But). While the diphenylphosphoryl complexes adopt a configuration with trans-pyrrolato ligands, the dicyclohexyl analogue prefers an all-cis conformation, with profound consequences on metal–ligand bonding. The reaction of sterically undemanding HNC4H3CH2P(O)Ph2 with Y[N(SiHMe2)2]3(THF)2 give the homoleptic complex Y[NC4H3CH2P(O)Ph2]3; mixed-ligand intermediates Y[N(SiHMe2)2]2(N–O) and Y[N(SiHMe2)2](N–O)2 were identifiable but could not be isolated. The bulky ligand HNC4H2(5-But)CH2P(O)Ph2 does not react with Ti(NMe2)4 but protolyses Zn[N(SiMe3)2]2 to give a 1 : 2 complex Zn(N–O)2 as the only isolable product. On the other hand, its reaction with Y[N(SiHMe2)2]3(THF)2 affords the mono-amido complex YN(SiHMe2)2}NC4H3(5-But)CH2P(O)Ph2}2 which shows good activity for the ring-opening polymerisation of cyclic esters.
二级膦 HPR2(R = Ph, Cy)与
吡咯-2-醛的反应生成了一类新的2-膦酰基甲基-1H-
吡咯,作为潜在的螯合单阴离子
配体。与Ti(NMe2)4的反应形成八面体Ti(NMe2)2NC4H2(4-R′)
CH2P(O)R2}2(R′ = H, But)。虽然二苯膦酰基配合物采用了带有反式
吡咯配体的构型,二环己基的类似物则更倾向于全顺式构象,这对
金属-
配体结合产生了深远的影响。体积较小的HNC4H3 (O)Ph2与Y[N(SiHMe2)2]3(THF)2的反应生成了均
配体络合物Y[NC4H3 (O)Ph2]3;可识别的混合
配体中间体Y[N(SiHMe2)2]2(N–O)和Y[N(SiHMe2)2](N–O)2,但无法分离。体积较大的
配体HNC4H2(5-But) (O)Ph2与Ti(NMe2)4不反应,但会对Zn[N(SiMe3)2]2进行质子化反应,生成唯一可分离的产物1:2络合物Zn(N–O)2。另一方面,其与Y[N(SiHMe2)2]3(THF)2的反应生成单酰胺配合物YN(SiHMe2)2}NC4H3(5-But) (O)Ph2}2,该化合物在环状酯的开环聚合中表现出良好的活性。