Department of Chemistry, University of Nevada-Las Vegas, Las Vegas, Nevada 89154, USA.
Inorg Chem. 2011 Feb 7;50(3):1039-46. doi: 10.1021/ic101779w. Epub 2010 Dec 29.
Trinuclear transition-metal complexes such as Re(3)X(9) (X = Cl, Br, I), with their uniquely featured structure among metal halides, have posed intriguing questions related to multicenter electron delocalization for several decades. Here we report a comprehensive study of the technetium halide clusters Tc(3)(μ-X)(3)X(6) (X = F, Cl, Br, I), isomorphous with their rhenium congeners, predicted from density functional theory calculations. The chemical bonding and aromaticity in these clusters are analyzed using the recently developed adaptive natural density partitioning method, which indicates that only Tc(3)X(9) clusters exhibit aromatic character, stemming from a d-orbital-based π bond delocalized over the three metal centers. We also show that standard methods founded on the nucleus-independent chemical shift concept incorrectly predict the neutral Tc(3)X(9) clusters to be aromatic.
三核过渡金属配合物，如 Re(3)X(9)（X = Cl、Br、I），因其在卤化物中独特的结构特征，几十年来一直引起人们对多中心电子离域的兴趣。在这里，我们报道了一项对铼同系物Tc(3)(μ-X)(3)X(6)（X = F、Cl、Br、I）的卤化物簇的综合研究，这些簇是通过密度泛函理论计算预测的，与它们具有同构性。使用最近开发的自适应自然密度分区方法分析了这些簇中的化学成键和芳香性，该方法表明，只有Tc(3)X(9)簇具有芳香特征，这源于三个金属中心之间基于 d 轨道的π键离域。我们还表明，基于核独立化学位移概念的标准方法错误地预测中性 Tc(3)X(9)簇具有芳香性。
