The photochemical reaction of Ru(CO)3(L)2, where L = PPh3, PMe3, PCy3 and P(p-tolyl)3 with parahydrogen (p-H2) has been studied by in-situ NMR spectroscopy and shown to result in two competing processes. The first of these involves loss of CO and results in the formation of the cis-cis-trans-L isomer of Ru(CO)2(L)2(H)2, while in the second, a single photon induces loss of both CO and L and leads to the formation of cis-cis-cis Ru(CO)2(L)2(H)2 and Ru(CO)2(L)(solvent)(H)2 where solvent = toluene, THF and pyridine (py). In the case of L = PPh3, cis-cis-trans-L Ru(CO)2(L)2(H)2 is shown to be an effective hydrogenation catalyst with rate limiting phosphine dissociation proceeding at a rate of 2.2 s−1 in pyridine at 355 K. Theoretical calculations and experimental observations show that H2 addition to the Ru(CO)2(L)2 proceeds to form cis-cis-trans-L Ru(CO)2(L)2(H)2 as the major product via addition over the π-accepting OC–Ru–CO axis.
我们通过原位核磁共振光谱研究了 Ru(CO)3(L)2(其中 L = PPh3、
PMe3、
PCy3 和 P(
对甲苯基)3)与对
氢(p-H2)的光
化学反应,结果表明该反应有两个相互竞争的过程。第一个过程涉及 CO 的损失,并形成 Ru(CO)2(L)2(H)2 的顺式-顺式-反式-L 异构体,而在第二个过程中,单个光子导致 CO 和 L 的损失,并形成顺式-顺式-Ru(CO)2(L)2(H)2 和 Ru(CO)2(L)(溶剂)(H)2,其中溶剂=
甲苯、
四氢呋喃和
吡啶 (py)。在 L = PPh3 的情况下,顺式-顺式-反式-L Ru(CO)2(L)2(H)2 被证明是一种有效的
氢化
催化剂,在 355 K 的
吡啶中,膦解离的速率限制为 2.2 s-1。理论计算和实验观察结果表明,向 Ru(CO)2(L)2加入 H2 后,通过在接受 π 的 OC-Ru-CO 轴上的加成,形成顺式-顺式-反式-L Ru(CO)2(L)2(H)2,作为主要产物。