Peng Bin, Li Qian-Shu, Xie Yaoming, King R Bruce, Schaefer Henry F
Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, China.
Dalton Trans. 2008 Dec 28(48):6977-86. doi: 10.1039/b810710f. Epub 2008 Oct 21.
For the saturated carbonyl trimer Ru(3)(CO)(12) theoretical methods predict a doubly bridged Ru(3)(CO)(10)(mu-CO)(2) structure to lie only 0.3 kcal mol(-1) above the unbridged global minimum in accord with the fluxional properties observed experimentally by carbon-13 NMR on the very stable unbridged Ru(3)(CO)(12). For M(3)(CO)(11) and M(3)(CO)(10) the global minima for the Fe, Ru, and Os derivatives each have totally different arrangements of the carbonyl groups. Thus the global minimum of Ru(3)(CO)(11) is singly edge-semibridged Ru(3)(CO)(10)(mu-CO) in contrast to the doubly face-bridged Fe(3)(CO)(9)(mu(3)-CO)(2) and triply edge-bridged Os(3)(CO)(8)(mu-CO)(3) found as global minima for the iron and osmium analogues, respectively. Furthermore, comparison of our predicted nu(CO) frequencies for low-lying unbridged, singly bridged, and doubly bridged isomers of Ru(3)(CO)(11) with the 1987 experiments of Bentsen and Wrighton indicates that three different Ru(3)(CO)(11) isomers are generated in these low-temperature inert matrix Ru(3)(CO)(12) photolysis experiments depending on the conditions. For Ru(3)(CO)(10) the global minimum is a triply bridged structure Ru(3)(CO)(7)(mu-CO)(3), which is very different from the Fe(3)(CO)(9)(mu(3)-CO) and Os(3)(CO)(8)(mu(3)-CO)(mu-CO) global minima found for the iron and osmium analogues, respectively. For Ru(3)(CO)(9) the global minimum is a singly bridged structure Ru(3)(CO)(8)(mu-CO) analogous to the global minimum for the osmium analogue but totally different from the triply bridged global minimum of Fe(3)(CO)(9).
对于饱和羰基三聚体Ru(3)(CO)(12)，理论方法预测双桥式Ru(3)(CO)(10)(μ-CO)(2)结构仅比非桥式全局最小值高0.3千卡/摩尔，这与通过碳-13 NMR在非常稳定的非桥式Ru(3)(CO)(12)上实验观察到的通量性质一致。对于M(3)(CO)(11)和M(3)(CO)(10)，铁、钌和锇衍生物的全局最小值各自具有完全不同的羰基排列。因此，Ru(3)(CO)(11)的全局最小值是单边缘半桥式Ru(3)(CO)(10)(μ-CO)，这与分别作为铁和锇类似物的全局最小值的双面桥式Fe(3)(CO)(9)(μ(3)-CO)(2)和三边桥式Os(3)(CO)(8)(μ-CO)(3)形成对比。此外，将我们预测的Ru(3)(CO)(11)的低位非桥式、单桥式和双桥式异构体的ν(CO)频率与1987年Bentsen和Wrighton的实验进行比较表明，在这些低温惰性基质Ru(3)(CO)(12)光解实验中，根据条件会生成三种不同的Ru(3)(CO)(11)异构体。对于Ru(3)(CO)(10)，全局最小值是三边桥式结构Ru(3)(CO)(7)(μ-CO)(3)，这与分别为铁和锇类似物找到的全局最小值Fe(3)(CO)(9)(μ(3)-CO)和Os(3)(CO)(8)(μ(3)-CO)(μ-CO)非常不同。对于Ru(3)(CO)(9)，全局最小值是单桥式结构Ru(3)(CO)(8)(μ-CO)，类似于锇类似物的全局最小值，但与Fe(3)(CO)(9)的三边桥式全局最小值完全不同。
