Riu Martin-Louis Y, Shan Jing-Ran, Houk K N, Nava Matthew
Department of Chemistry and Biochemistry, University of California Los Angeles California 90095-1569 USA
Chem Sci. 2025 Jan 22;16(9):3888-3894. doi: 10.1039/d4sc07938h. eCollection 2025 Feb 26.
Group 13 aminoxy complexes of the form (L)E(TEMPO) (TEMPO = 2,2,6,6-tetramethylpiperidine 1-oxyl; L = THF (tetrahydrofuran) or Py (pyridine); E = Al, Ga, In) were prepared and structurally characterized. The complexes (THF)Ga(TEMPO) (1·THF) and (Py)In(TEMPO) (2·Py) are shown to heterolytically cleave H under mild conditions (3 atm, 20 °C, ≤ 1 h). 1·THF reacts reversibly with H to form a formal H-adduct that bears a Ga(iii) hydride site and a protonated TEMPO ligand with concomitant loss of THF, consistent with Ga(iii) and TEMPO functioning as Lewis acid and base, respectively. Conversely, 2·Py is reduced by H to form an intermediate dimer complex of monovalent {In(TEMPO)}, which undergoes further reactivity with H to form elemental indium as determined by powder X-ray diffraction. Treatment of 2·Py with H and PhPSe forms binary InSe, in addition to PhP and TEMPOH, demonstrating that 2·Py functions as a molecular source of zero-valent indium under mildly reducing conditions. Computational studies support an intramolecular metal-ligand cooperativity pathway in the heterolytic cleavage of H.
制备并对形式为(L)E(TEMPO)（TEMPO = 2,2,6,6 - 四甲基哌啶1 - 氧基；L = 四氢呋喃(THF)或吡啶(Py)；E = Al、Ga、In）的第13族氨氧基配合物进行了结构表征。配合物(THF)Ga(TEMPO) (1·THF)和(Py)In(TEMPO) (2·Py)在温和条件下（3个大气压，20 °C，≤1小时）可异裂裂解H。1·THF与H可逆反应形成一种形式上的H加合物，该加合物含有一个Ga(iii)氢化物位点和一个质子化的TEMPO配体，同时THF损失，这与Ga(iii)和TEMPO分别作为路易斯酸和碱的作用一致。相反，2·Py被H还原形成一价{In(TEMPO)}的中间二聚体配合物，通过粉末X射线衍射确定，该配合物与H进一步反应形成元素铟。用H和PhPSe处理2·Py，除了生成PhP和TEMPOH外，还生成二元InSe，这表明2·Py在温和还原条件下作为零价铟的分子源。计算研究支持了H异裂裂解过程中的分子内金属 - 配体协同作用途径。
