Hydroboration of a Diolate Complex Obtained by Carbon Dioxide Capture with Acenaphthenediimine Aluminum Hydride
Tatyana S. Koptseva, Alexandra A. Skatova, Sergey Yu. Ketkov, Elena Rychagova, Roman V. Rumyantcev, Igor L. Fedushkin
Abstract
The reduction of diolate [{(dpp-bian)Al(μ-O2CH2)}2] (1), bearing a redox-active acenaphthene-1,2-diimine ligand (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]-acenaphthene), by boranes has been studied. The reaction of 1 with HBpin proceeds with reduction of the C–O bonds in the −O–CH2–O– fragments and results in [{(dpp-bian)Al(OCH3)}(μ-O){Al(OBpin)(dpp-bian)}] (2) and pinBOCH3. The reduction of 1 by HBcat leads to the formation of the compound [{(dpp-bian)Al(μ-Cat)}2] (3) and (CH3OBO)3. BH3·SMe2 reduces diolate 1 to form the complex [{(dpp-bian)Al(OCH3)}(μ-O){Al(OCH2OBH2)(dpp-bian)}] (4). Compounds 2–4 have been characterized by electron paramagnetic resonance and infrared spectroscopy, and their molecular structures have been determined by single-crystal X-ray analysis. Density functional theory calculations have been performed to analyze the reaction energies and a possible mechanism of an initial stage as well as to explain the different product types.