Department of Chemistry and Pharmacy, Inorganic Chemistry, University of Erlangen-Nuremberg, Erlangen, Germany.
J Am Chem Soc. 2012 Aug 1;134(30):12792-7. doi: 10.1021/ja3047393. Epub 2012 Jul 16.
The previously reported uranium(III) complex [(((Ad)ArO)(3)N)U(III)(DME)] (1; Ad = adamantane, DME = 1,2-dimethoxyethane) reacts with the terminal bis-alkynes 1,7-octadiyne or 1,6-heptadiyne in C-C-coupling reactions to form the uranium(IV) vinyl complexes [{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2):η(1)-1,2-(CH)(2)-cyclohexane)] (2) and [{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2):η(2)-1,2-(CH)(2)-cyclopentane)] (3). With the monoalkynes 1-hexyne or 4-(t)butyl-phenylacetylene, the complexes [{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2)(C1):η(1)(C4)-2-(n)Bu-1,3-octadiene)] (4) and [{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2)(C4):η(1)(C1)-1,3-di-(p-(t)Bu-phenyl)butadiene))] (5), are formed. These are the first four examples of uranium vinyl complexes that are reported and crystallographically characterized. In addition, detailed DFT calculations are presented to establish a possible mechanism for their formation and explain the differences found for the coordination of the hydrocarbon fragments. In contrast to a previously proposed monometallic pathway for catalytic hydroamination of alkynes and alkyne dimerization involving a uranium vinyl intermediate at uranium(III) complexes, the calculations clearly support a bimetallic mechanism, since its transition states are energetically the most favored.
先前报道的铀(III)配合物[(((Ad)ArO)(3)N)U(III)(DME)]（1；Ad = 金刚烷，DME = 1,2-二甲氧基乙烷）与末端双炔 1,7-辛二炔或 1,6-庚二炔在 C-C 偶联反应中反应，形成铀(IV)乙烯基配合物[{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2):η(1)-1,2-(CH)(2)-环己烷)]（2）和[{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2):η(2)-1,2-(CH)(2)-环戊烷)]（3）。对于单炔 1-己炔或 4-(t)丁基-苯乙炔，配合物[{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2)(C1):η(1)(C4)-2-(n)Bu-1,3-辛二烯)]（4）和[{(((Ad)ArO)(3)N)U(IV)}(2)(μ-η(2)(C4):η(1)(C1)-1,3-二-(p-(t)Bu-苯)丁二烯))]（5）形成。这些是报告的和晶体结构表征的第一个铀乙烯基配合物的四个实例。此外，还提出了详细的 DFT 计算，以建立其形成的可能机制，并解释在烃片段配位方面发现的差异。与先前提出的涉及铀(III)配合物中铀乙烯基中间体的炔烃催化氨化和炔烃二聚的单金属途径不同，计算结果清楚地支持双金属机制，因为其过渡态在能量上是最有利的。
