The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines promoted by the hexahydride complex OsH₆(PⁱPr₃)₂ (1) is described, and the mechanisms of the reactions involved are established. Complex 1 catalyzes the aforementioned transformations of aryl-, pyridyl-, and alkoxy-functionalized alkyl nitriles with linear or branched chains. The formation of the secondary amines involves primary imines, primary amines, and secondary imines as organic intermediates. The reactions take place under mild conditions (toluene, 100 °C, and 4 bar of H₂). Stoichiometric reactions of 1 with pivalonitrile and 2-methoxyacetonitrile have allowed us to isolate the trihydride azavinylidene derivatives OsH₃{═N═CHR}(PⁱPr₃)₂ (R = ^tBu (3), CH₂OMe (4)). Their formation involves the insertion of the N–C triple bond of the substrates into an Os–H bond of the unsaturated tetrahydride OsH₄(PⁱPr₃)₂ (A), which is generated by reductive elimination of H₂ from the hexahydride precursor. The reaction of these trihydride azavinylidene species with H₂ is the key step for the reduction of the N–C triple bond of the nitriles. In the absence of H₂, the attack of A to the azavinylidene ligand produces the rupture of its C(sp²)–C(sp³) bond. As a consequence of this attack and the presence of primary imines and amines in the reaction media, the binuclear complexes (PⁱPr₃)₂H₄Os(μ-CN)OsH₃{κ¹-N-(NH═CHCH₂OMe)}(PⁱPr₃)₂ (5) and (PⁱPr₃)₂H₄Os(μ-CN)OsH₃{κ¹-N-(NH₂CH₂CH₂OMe)}(PⁱPr₃)₂ (6) have been isolated and characterized by X-ray diffraction analysis, for 2-methoxyacetonitrile. DFT calculations reveal noticeable similarities between the hydrogenations of nitriles to primary imines and those of primary imines to primary amines.

中文翻译：

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s促进烷基腈向脂肪族仲胺的转化：范围和机理

描述了由六氢化物配合物OsH ₆（P ⁱ Pr ₃）₂（1）促进的烷基腈向对称和不对称仲脂肪族仲胺的转化，并建立了涉及的反应机理。配合物1催化具有直链或支链的芳基，吡啶基和烷氧基官能化的烷基腈的上述转化。仲胺的形成涉及伯亚胺，伯胺和仲亚胺作为有机中间体。反应在温和的条件下（甲苯，100°C和4 bar H ₂）进行。1的化学计量反应与新戊腈和2-甲氧基乙腈一起使我们能够分离三氢化物氮杂亚乙烯基衍生物OsH ₃ {═N═CHR}（P ⁱ Pr ₃）₂（R = ^t Bu（3），CH ₂ OMe（4））。它们的形成涉及将底物的N–C三键插入不饱和四氢化物OsH ₄（P ⁱ Pr ₃）₂（A）的Os–H键中，这是通过从六氢化合物中消除H ₂产生的前体。这些三氢化物氮杂亚乙烯基物质与H ₂的反应是还原腈的N-C三键的关键步骤。在没有H ₂的情况下，A对氮杂亚乙烯基配体的攻击会导致其C（sp ²）–C（sp ³）键断裂。作为这种攻击的结果和主亚胺和胺的反应介质的存在下，所述双核络合物（P^我镨₃）₂ ħ ₄ OS（μ-CN）OSH ₃ {κ ¹ - ñ - （NH═CHCH ₂ OMe）}（P ⁱ Pr ₃）₂（5）和（P ⁱ Pr ₃）₂ ħ ₄ OS（μ-CN）OSH ₃ {κ ¹ - ñ - （NH ₂ CH ₂ CH ₂ OME）}（P^我镨₃）₂（6）已被分离和表征通过X射线衍射分析，用于2-甲氧基乙腈。DFT计算显示腈加氢成伯亚胺的氢化和伯亚胺加成伯胺的氢化之间的显着相似性。