Insertion Reactions of Carbon Dioxide into Zn−N Bonds: Syntheses and Structures of Tetrameric and Dimeric Alkylzinc Carbamato Complexes

The formal insertions of carbon dioxide into a series of methylzinc dialkylamide complexes (MeZnNR2) initially form
solvent-free, tetrameric zinc carbamato complexes [Me4Zn4(O2CNR2)4] (NR2 = N(i-Pr)2 (1), N(i-Bu)2 (2), and piperidinyl
(3)). These compounds have been characterized by traditional techniques as well as by single-crystal X-ray diffraction
analyses. The tetrameric backbones seen in the solid state for 1−3 were structurally similar to each other. Addition
of excess pyridine (py) to 1−3 breaks apart the tetramers and converts them into solvated dimeric species [Me2Zn2(O2CNR2)2(py)2] (NR2 = N(i-Pr)2 (4), N(i-Bu)2 (5), and piperidinyl (6)). X-ray crystallographic analyses of 4 and
5 confirmed the dimeric structure in the solid state. This study significantly increases the number of well-characterized
zinc carbamates prepared via CO2 insertion into zinc amides.

将二氧化碳的正式插入反应应用于一系列二烷基氨基甲基锌配合物（methylzinc dialkylamide complexes，MeZnNR₂）中，首先会生成无溶剂型四聚体氨基甲酸锌配合物[Me₄Zn₄(O₂CNR₂)₄]，其中NR₂分别为N(异丙基)₂（1）、N(异丁基)₂（2）以及哌啶基（3）。上述化合物通过传统表征技术以及单晶X射线衍射（single-crystal X-ray diffraction）分析完成了结构表征。固态下1~3的四聚体骨架结构彼此相似。向1~3中加入过量吡啶（pyridine，py）后，四聚体结构发生解离，并转化为溶剂化二聚体物种[Me₂Zn₂(O₂CNR₂)₂(py)₂]，其中NR₂分别为N(异丙基)₂（4）、N(异丁基)₂（5）以及哌啶基（6）。对4和5的X射线晶体衍射分析证实了其固态下的二聚体结构。本研究大幅提升了通过二氧化碳插入锌酰胺制备且得到充分表征的氨基甲酸锌类化合物的数量。