Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Am Chem Soc. 2010 Feb 24;132(7):2169-71. doi: 10.1021/ja910445r.
The terminal nitride anion complex [Na][N[triple bond]Nb(N[(t)Bu]Ar)(3)] ([Na][1], Ar = 3,5-Me(2)C(6)H(3)) reacts quantitatively with CO(2) to give the carbamate complex [Na][O(2)CN[triple bond]Nb(N[(t)Bu]Ar)(3)] ([Na][O(2)C-1]). The structure of [Na][O(2)C-1] as the bis-12-crown-4 solvate, as determined by X-ray crystallography, displays a unique N-bound carbamate ligand without any metal-oxygen interactions. When treated with organic acid anhydrides or acid chlorides, complex [Na][O(2)C-1] reacts via salt elimination to give the five-coordinate complexes (RC(O)O)(OCN)Nb(N[(t)Bu]Ar)(3) (R-2, R = Me, (t)Bu, F(3)C). We show that complexes R-2 yield the starting complex [Na][1] with concomitant release of CO upon two-electron reduction. This series of reactions constitutes a closed cycle for the conversion of CO(2) to CO mediated by a terminal nitride anion complex.
终端氮化物阴离子配合物 [Na][N[三重键]Nb(N[(t)Bu]Ar)(3)] ([Na][1]，Ar = 3,5-Me(2)C(6)H(3)) 与 CO(2) 定量反应生成氨基甲酸酯配合物 [Na][O(2)CN[三重键]Nb(N[(t)Bu]Ar)(3)] ([Na][O(2)C-1])。通过 X 射线晶体学确定的 [Na][O(2)C-1] 作为双-12-冠-4 溶剂化物的结构显示了独特的 N 键氨基甲酸酯配体，没有任何金属-氧相互作用。当与有机酸酐或酰氯反应时，配合物 [Na][O(2)C-1] 通过盐消除反应生成五配位配合物 (RC(O)O)(OCN)Nb(N[(t)Bu]Ar)(3) (R-2，R = Me，(t)Bu，F(3)C)。我们表明，配合物 R-2 在两电子还原时会释放 CO 并生成起始配合物 [Na][1]。这一系列反应构成了由终端氮化物阴离子配合物介导的 CO(2) 到 CO 的转化的闭环循环。
