Lithium, Magnesium, and Zinc Iminophosphorano(8-quinolyl)methanide Complexes: Syntheses, Characterization, and Activity in ε-Caprolactone Polymerization

Lithiation of R2P(CH2C9H6N-8)NBut (R = Ph, 3; R = Pri, 4) with an equivalent of BunLi afforded lithium iminophosphorano(8-quinolyl)methanide [Li{CH(8-C9H6N)P(Ph2)NBut}(THF)] (5) and [Li{CH(8-C9H6N)P(Pri2)NBut}]2 (6), respectively. Reaction of 4 with Et2Mg yielded magnesium iminophosphorano(8-quinolyl)methanide complex (7). Treatment of 6 with ZnCl2 gave [Zn(Cl){CH(8-C9H6N)P(Pri2)NBut}] (8), which was transformed into alkylated zinc complexes [Zn(R1){CH(8-C9H6N)P(Pri2)NBut}] (R1 = Ph, 9; R1 = Me, 10) by treating with R1Li or R1MgX. Ethylzinc complexes [Zn(Et){CH(8-C9H6N)P(R2)NBut}] (R = Ph, 11; R = Pri, 12) were obtained by reaction of 3 or 4 with an equivalent of Et2Zn. Compounds 2 and 4−12 were characterized by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy and elemental analyses. Structures of complexes 6−8 and 10 were further characterized by single-crystal X-ray diffraction techniques. The catalytic behaviors of complexes 7 and 9−12 in the ring-opening polymerization of ε-caprolactone was studied. Complex 7 exhibited high catalytic activity in the presence or absence of benzyl alcohol. Complexes 9−12 catalyzed the ring-opening polymerization of ε-CL in the presence of benzyl alcohol and exhibited first-order dependence on monomer concentration.

以等当量正丁基锂(BunLi)对R₂P(CH₂C₉H₆N-8)N-叔丁基（R = 苯基(Ph)，对应化合物3；R = 异丙基(Pri)，对应化合物4）进行锂化反应，分别得到亚胺基膦烷(8-喹啉基)甲基锂配合物[Li{CH(8-C₉H₆N)P(Ph₂)N-叔丁基}(THF)]（5）和二聚体配合物[Li{CH(8-C₉H₆N)P(Pri₂)N-叔丁基}]₂（6）。将化合物4与二乙基镁(Et₂Mg)反应，得到亚胺基膦烷(8-喹啉基)甲基镁配合物（7）。将化合物6与氯化锌(ZnCl₂)反应，得到[Zn(Cl){CH(8-C₉H₆N)P(Pri₂)N-叔丁基}]（8）；该配合物可与烷基锂(R₁Li)或格氏试剂(R₁MgX)发生烷基化反应，转化为烷基锌配合物[Zn(R₁){CH(8-C₉H₆N)P(Pri₂)N-叔丁基}]（R₁ = 苯基(Ph)，对应化合物9；R₁ = 甲基(Me)，对应化合物10）。通过化合物3或4与等当量二乙基锌(Et₂Zn)反应，可制备乙基锌配合物[Zn(Et){CH(8-C₉H₆N)P(R₂)N-叔丁基}]（R = Ph，对应化合物11；R = Pri，对应化合物12）。采用¹H核磁共振谱、¹³C{¹H}核磁共振谱及³¹P{¹H}核磁共振谱和元素分析对化合物2、4~12进行了结构表征。通过单晶X射线衍射技术进一步确定了配合物6~8和10的晶体结构。研究了配合物7、9~12在ε-己内酯(ε-CL)开环聚合中的催化性能：配合物7在有无苯甲醇的条件下均表现出高催化活性；配合物9~12在苯甲醇存在下可催化ε-己内酯开环聚合，且聚合反应速率对单体浓度呈现一级动力学依赖关系。