Departamento de Físico-Química, Universidade Federal Fluminense, Outeiro de São João Batista, Niterói, RJ, Brazil.
J Mol Model. 2010 Aug;16(8):1415-20. doi: 10.1007/s00894-010-0662-3. Epub 2010 Feb 17.
Through-space NMR shieldings were calculated for trinuclear metal-carbonyl compounds [M(3)(CO)(12)] (M = Fe, Ru, Os), employing the nucleus-independent chemical shift approach. The through-space shieldings were visualized as a contour plot of iso-chemical shielding surfaces, and were applied to quantify the overall anisotropic effect of the carbonyl groups, as well as to identify the influence of the transition metal on the scopes of the corresponding anisotropy cones. The shielding surfaces show that the anisotropic effect of the carbonyl groups at equatorial positions changes depending on the metal. This effect was associated with pi-backdonation from the metal to the carbonyl groups in that position, in agreement with geometric data as well as calculated NMR parameters. Therefore, visualization of the through-space NMR shieldings of trinuclear metal-carbonyl compounds of group 8 is able to reflect the distinct arrangements of the carbonyl groups in these organometallic compounds.
通过空间 NMR 屏蔽被计算为三核金属羰基化合物 [M(3)(CO)(12)]（M = Fe，Ru，Os），采用核独立化学位移方法。通过空间屏蔽被可视化作为等化学屏蔽表面的等高线图，并被应用于量化羰基的整体各向异性效应，以及识别过渡金属对相应各向异性锥范围的影响。屏蔽表面表明，在赤道位置的羰基的各向异性效应取决于金属。这种效应与来自金属到该位置的羰基的 pi-backdonation 有关，这与几何数据以及计算的 NMR 参数一致。因此，对第 8 族三核金属羰基化合物的通过空间 NMR 屏蔽的可视化能够反映这些金属有机化合物中羰基的不同排列。
