Reactivity of the terminal oxo species (((t)Bu2PCH2SiMe2)2N)RhO.
Reactivity of the terminal oxo species (((t)Bu2PCH2SiMe2)2N)RhO.
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DOI：
10.1039/c3dt31972e
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发表时间：
2013-04
影响因子：
4
通讯作者：
N. Tsvetkov;J. Andino;Hongjun Fan;A. Verat;K. G. Caulton
中科院分区：
文献类型：
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作者：
N. Tsvetkov;J. Andino;Hongjun Fan;A. Verat;K. G. Caulton
四配位分子Rho(PnP是((T)Bu2PCH2SiMe2)2N)对CO的反应是逐步进行的，首先通过CO在Rh上的初步加合反应生成η(2)-CO络合物，然后第二个CO取代CO。氧配合物与二氧化碳的反应即使在低温下也会在混合时发生，生成(PnP)Rh(η(2)-CO3)，中间体检测不到。密度泛函理论计算表明，氧中心和二氧化碳碳之间形成了初始的键。(PNP)Rho与H2仅在1：2摩尔化学计量比下发生反应，最终生成(PNP)Rh(H)2和游离H2O。即使在-60°C下也没有中间体到达可检测到的布居，但对单重态能面上各种可能的机制的密度泛函映射表明，形成了近等能的(PNP)Rh(H2O)和(PNP)RHH(OH)，但只有后者容易地添加第二个H2分子来进行观察到的产物；因此，这两个反应都涉及H2的异解分裂。
Reactivity of the 4-coordinate molecule (PNP)RhO (PNP is ((t)Bu2PCH2SiMe2)2N) towards CO proceeds stepwise, first forming an η(2)-CO2 complex, by a mechanism which involves a preliminary adduct of CO on Rh, then a second CO displaces CO2. Reaction of the oxo complex with CO2 occurs in time of mixing even at low temperature to form (PNP)Rh(η(2)-CO3), with no intermediate detectable. DFT calculations indicate an initial bond formation between the oxo center and the CO2 carbon. Reaction of (PNP)RhO with H2 occurs only at a 1 : 2 molar stoichiometry, to ultimately form (PNP)Rh(H)2 and free H2O. No intermediate reaches detectable population even at -60 °C, but DFT mapping of various possible mechanisms on the singlet energy surface shows that the nearly equi-energetic (PNP)Rh(H2O) and (PNP)RhH(OH) are formed, but only the latter readily adds the second molecule of H2 to proceed to the observed products; these reactions thus both involve heterolytic splitting of H2.