A boron, nitrogen-containing heterocyclic carbene (BNC) as a redox active ligand: synthesis and characterization of a lithium BNC-aurate complex
A boron, nitrogen-containing heterocyclic carbene (BNC) as a redox active ligand: synthesis and characterization of a lithium BNC-aurate complex
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作为氧化还原活性配体的含硼氮杂环卡宾（BNC）：BNC-金酸锂配合物的合成和表征
DOI：
10.1039/d2dt01083f
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发表时间：
2022
影响因子：
4
通讯作者：
Shang Rong
中科院分区：
文献类型：
--
作者：
Kimura Yoshitaka;Lugo-Fuentes Leonardo I.;Saito Souta;Jimenez-Halla J. Oscar C.;Barroso-Flores Joaquin;Yamamoto Yohsuke;Nakamoto Masaaki;Shang Rong
由于低价金中心易于簇合，通过有机配体稳定低氧化金阴离子如金酸盐或金化物长期以来一直是合成的挑战。尽管是电负性最强的金属，但可分离的金（I）酸盐配合物仅从少数吸σ有机基和有机基主基配体获得。通过π-调节氧化还原活性配体稳定高度还原的金络合物仅通过环状（氨基）（烷基）卡宾（CAAC）实现，其仅限于1 e −还原以形成中性金（0）络合物。本工作报道了一种简单的模块化合成的硼，氮杂环卡宾（ClBNC）在金（I）中心通过金属辅助偶联氮杂二硼和异腈。金（I）配合物[（ClBNC）AuPMe 3]（3a和3b）中的阴离子亲电ClBNC配体允许2 e −还原形成第一个η1-卡宾金酸盐配合物[（BNC）AuPMe 3]Li（DME）（5a，DME =二甲氧基乙烷）。这些配合物的单晶晶体学分析和计算研究揭示了中性4π B，N-杂环卡宾（BNC）部分的高π-吸走特性和6π弱芳族特性，其对还原形式的金（I）片段具有π-供给特性，展示了第一个允许π-吸走（Fischer型）和π-供给（Schrock型）特性之间的电子可调谐性的环状卡宾配体。
Stabilization of low oxidation gold anions as aurate or auride by organic ligands has long been a synthetic challenge, owing to the proneness of low-valent gold centres to cluster. Despite being the most electronegative metal, isolable gold(I) aurate complexes have only been obtained from a few σ-withdrawing organo- and organo-main group ligands. Stabilization of highly-reduced gold complexes by π-modulating redox active ligands has only been achieved by cyclic (amino)(alkyl)carbene (CAAC), which is limited to 1e−-reduction to form neutral gold(0) complexes. This work reports a simple modular synthesis of a boron, nitrogen-containing heterocyclic carbene (ClBNC) at a gold(I) center through metal-assisted coupling between azadiboriridine and isocyanides. The anionic electrophilic ClBNC ligand in the gold(I) complex [(ClBNC)AuPMe3] (3a and 3b) allows a 2e−-reduction to form the first η1-carbene aurate complex [(BNC)AuPMe3]Li(DME) (5a, DME = dimethoxyethane). Single crystal crystallographic analysis and computational studies of these complexes revealed a highly π-withdrawing character of the neutral 4π B,N-heterocyclic carbene (BNC) moiety and a 6π weakly aromatic character with π-donating properties to the gold(I) fragment in its reduced form, showcasing the first cyclic carbene ligand that allows electronic tunability between π-withdrawing (Fischer-type)- and π-donating (Schrock-type) properties.