[MnBrL(CO)4] (L = Amidinatogermylene): Reductive Dimerization, Carbonyl Substitution, and Hydrolysis Reactions

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• 作者：Javier A. Cabeza ; Pablo García-Álvarez ; Roberto Gobetto ; Laura González-Álvarez ; Carlo Nervi ; Enrique Pérez-Carreño ; Diego Polo
• 刊名：Organometallics
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：35
• 期：11
• 页码：1761-1770
• 全文大小：538K
• 年卷期：0
• ISSN：1520-6041

文摘

The manganese(I) carbonyl complex [MnBr{Ge(ⁱPr₂bzam)^tBu}(CO)₄] (1; ⁱPr₂bzam = 1,3-di(isopropyl)benzamidinate), which contains an amidinatogermylene ligand, reacts with LiPh or Li^tBu at room temperature undergoing a reductive dimerization process that leads to the manganese(0) dimer [Mn₂{Ge(ⁱPr₂bzam)^tBu}₂(CO)₈]. This complex and the monosubstituted derivative [Mn₂{Ge(ⁱPr₂bzam)^tBu}(CO)₉] have also been prepared by reacting [Mn₂(CO)₁₀] with Ge(ⁱPr₂bzam)^tBu at high temperature (110 °C). These binuclear complexes contain their germylene ligands in axial positions (trans to the Mn–Mn bond). The large volume of the germylene ligand clearly affects the reactivity of complex 1 with neutral two-electron donor reagents, since for bulky reagents, the CO substitution occurs trans to the germylene ligand, as in trans-mer-[MnBrL{Ge(ⁱPr₂bzam)^tBu}(CO)₃] (L = Ge(ⁱPr₂bzam)^tBu, PMe₃), whereas for small reagents, the CO substitution occurs cis to the germylene ligand, as in fac-[MnBr(CN^tBu){Ge(ⁱPr₂bzam)^tBu}(CO)₃]. The IR spectra (ν_CO) of these complexes have confirmed that the germylene Ge(ⁱPr₂bzam)^tBu is a very strong electron-donating ligand, even stronger than the most basic trialkylphosphanes and N-heterocyclic carbenes. The hydrolysis of complex 1 leads to the salt [ⁱPr₂bzamH₂][MnBr{Ge(OH)₂^tBu}(CO)₄], the anion of which contains an unprecedented germanato(II) ligand, [Ge(OH)₂^tBu]⁻, in cis to the Br atom. This hydrolysis product and its precursor 1 have been tested as catalyst precursors for the electrolytic reduction of CO₂, showing no significant activity.