Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore, 560012, Karnataka, India.
Chemistry. 2018 Dec 3;24(67):17844-17851. doi: 10.1002/chem.201804599. Epub 2018 Nov 9.
A detailed molecular orbital analysis of the metal-bis(borylene) complex [Fe(CO) {B(Dur)B(N(SiMe ) )}] (Dur=2,3,5,6-tetramethylphenyl) (1 a) serves as a focal point of recent developments in this area of chemistry, such as B-B coupling and B-B catenation reactions. There is strong a π delocalization between the Fe(CO) and (B-Dur)(B-N(SiMe ) ) units; the short B-B distance in 1 a is due to this π delocalization. The π-donor ligand N(SiMe ) on the boron provides a decisive stability to the complex 1 a. The LUMO of 1 a has B-B σ-bonding character. Hence B-B coupling is facilitated by filling the LUMO. Strong σ-donating ligands, such as PMe or PCy , induce B-B coupling. Expulsion of one CO from 1 a followed by dimerization leads to [Fe(CO) {B(Dur)B(N(SiMe ) )}] (3 a) with a short Fe-Fe distance of 2.355 Å. A detailed mechanism for the reaction of 3 a with CO to give the B-B catenation product 2 f is presented. The bonding of all intermediates is compared to their isolobal main-group analogues.
对金属双（硼烯）配合物[Fe(CO) {B(Dur)B(N(SiMe ) )}]（Dur=2,3,5,6-四甲基苯基）（1a）的详细分子轨道分析是该化学领域近期发展的重点，例如 B-B 偶联和 B-B 交织反应。Fe(CO) 和 (B-Dur)(B-N(SiMe ) ) 单元之间存在强烈的π离域；1a 中短的 B-B 距离归因于这种π离域。硼上的给电子配体 N(SiMe ) 为配合物 1a 提供了决定性的稳定性。1a 的 LUMO 具有 B-B σ 键合特征。因此，通过填充 LUMO 促进 B-B 偶联。强σ供体配体，如 PMe 或 PCy ，诱导 B-B 偶联。从 1a 中逐出一个 CO 后，二聚化导致具有 2.355 Å 短 Fe-Fe 距离的[Fe(CO) {B(Dur)B(N(SiMe ) )}]（3a）。提出了 3a 与 CO 反应生成 B-B 交织产物 2f 的详细反应机制。比较了所有中间体的键合与其等电子主族类似物。
