Chen Teng-Teng, Cheung Ling Fung, Chen Wei-Jia, Cavanagh Joseph, Wang Lai-Sheng
Department of Chemistry, Brown University, Providence, RI, 02912, USA.
Angew Chem Int Ed Engl. 2020 Aug 24;59(35):15260-15265. doi: 10.1002/anie.202006652. Epub 2020 Jun 9.
Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal d →BR back-donation, despite the electron deficiency of boron. An electron-precise metal-boron triple bond was first observed in BiB O [Bi≡B-B≡O] in which both boron atoms can be viewed as sp-hybridized and the [B-BO] fragment is isoelectronic to a carbyne (CR). To search for the first electron-precise transition-metal-boron triple-bond species, we have produced IrB O and ReB O and investigated them by photoelectron spectroscopy and quantum-chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB O has a closed-shell bent structure (C , A') with BO coordinated to an Ir≡B unit, ( OB)Ir≡B, whereas ReB O is linear (C , Σ ) with an electron-precise Re≡B triple bond, [Re≡B-B≡O] . The results suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems.
尽管硼存在电子不足的情况，但在许多硼烯（:BR）配合物中，通过金属d→BR的反馈π键，硼与过渡金属之间的多重键是已知的。在BiB₂O₃[Bi≡B - B≡O]中首次观察到电子精确的金属 - 硼三键，其中两个硼原子都可视为sp杂化，且[B - BO]片段与卡宾（CR）等电子。为了寻找首个电子精确的过渡金属 - 硼三键物种，我们制备了IrB₂O₃和ReB₂O₃，并通过光电子能谱和量子化学计算对它们进行了研究。结果有助于阐明这两个簇合物的结构和键合情况。我们发现IrB₂O₃具有闭壳弯曲结构（C₂v，A₁'），其中BO与Ir≡B单元配位，即(OB)Ir≡B，而ReB₂O₃是线性的（C∞v，Σg⁺），具有电子精确的Re≡B三键，即[Re≡B - B≡O]。结果表明，合成类似于经典卡宾体系的具有电子精确M≡B三键的化合物具有引人入胜但充满挑战的可能性。 （注：原文中最后一句“suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems.”直译为“表明合成与经典卡宾体系类似的具有电子精确M≡B三键的化合物的有趣可能性”，在中文语境下不太通顺，调整为更符合表达习惯的表述，但未改变原意。）
