(13)CO exchange studies of racemization catalyst (eta(5)-Ph(5)C(5))Ru(CO)(2)Cl and (eta(5)-Ph(5)C(5))Ru(CO)(2)(Ot-Bu) by (13)C NMR spectroscopy are reported. CO exchange for the active catalyst form, (eta(5)-Ph(5)C(5))Ru(CO)(2)(Ot-Bu) is approximately 20 times faster than that for the precatalyst (eta(5)-Ph(5)C(5))Ru(CO)(2)Cl. An inhibition on the rate of racemization of (S)-1-phenylethanol was observed on addition of CO. These results support the hypothesis that CO dissociation is a key step in the racemization of sec-alcohols by (eta(5)-Ph(5)C(5))Ru(CO)(2)Cl, as also predicted by DFT calculations.
基于13C NMR光谱学对消旋
催化剂(η⁵-Ph₅C₅)Ru(CO)₂Cl和(η⁵-Ph₅C₅)Ru(CO)₂(Ot-Bu)的13CO交换研究已得到报告。活性
催化剂形式(η⁵-Ph₅C₅)Ru(CO)₂(Ot-Bu)中的CO交换速率相较于前
催化剂(η⁵-Ph₅C₅)Ru(CO)₂Cl快约20倍。观察到添加CO时,(S)-1-
苯乙醇的消旋速率被抑制。这些结果支持如下假说:CO解离是(η⁵-Ph₅C₅)Ru(CO)₂Cl催化付
烯醇类化合物消旋过程的关键步骤,这一结论也得到了DFT计算的预测支持。