Hydration of Aliphatic Nitriles Catalyzed by an Osmium Polyhydride: Evidence for an Alternative Mechanism
作者:Juan C. Babón、Miguel A. Esteruelas、Ana M. López、Enrique Oñate
DOI:10.1021/acs.inorgchem.1c00380
日期:2021.5.17
competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings
六氢化物 OsH 6 (P i Pr 3 ) 2有效地催化脂肪族腈水合为酰胺。催化条件下的主要金属物种是三氢化锇(IV)酰胺化物衍生物OsH 3 κ 2 - N , O -[HNC(O)R]}(P i Pr 3 ) 2,它们已被分离和充分表征对于 R = i Pr 和t卜。水合速率与催化剂前体、腈和水的浓度成正比。当这些实验结果和密度泛函理论计算相结合时,催化机制已经建立。配合物OsH 3 κ 2 - N , O -[HNC(O)R]}(P i Pr 3 ) 2解离螯合物的羰基,得到与腈配位的κ 1 - N -酰胺衍生物。随后外部水分子攻击腈的 C(sp) 原子和酰胺化物的 N 原子,得到酰胺并再生 κ 1 - N-酰胺催化剂。该攻击是协同的,并通过循环六元过渡态发生,其中涉及 C腈···O-H···N酰胺相互作用。在攻击之前,κ 1 - N -酰胺配体的游离羰基将水分子固定在腈的 C(sp)