Organisch-Chemisches Institut, Westfälische Wilhelms Universität, D-48149 Münster, Germany.
Inorg Chem. 2010 Mar 15;49(6):2911-9. doi: 10.1021/ic9024662.
The concept of a dative metal-metal bond is generally used to designate the donor-acceptor (DA) interaction of an electron-saturated metal center with another electron-deficient--or unsaturated--metal center. This type of DA bonding extended to the field of coordination complexes constitutes a borderline case of weak metal-metal interaction, among which the so-called metallophilic interactions occurring with 4d, 5d, and other late-transition-metal complexes are the most documented and representative examples. From a general standpoint, the peculiar position of the so-called dative metal-metal bond in chemical bonding stems from its presumed covalent character, which contrasts with the situation encountered with metallophilic interactions, which are essentially supported by dispersion and electrostatic forces and somewhat sustained by relativistic effects. In this study, the nature of the metal-metal bond in nonbridged 5d-3d Os-Cr and 5d-5d Os-W adducts, i.e., (Me(3)P)(CO)(4)Os-M(CO)(5) (M = Cr, W) and (CO)(5)Os-Cr(CO)(5), was addressed by resorting to state-of-the-art quantum-chemical methods. Semilocal density functional theory (DFT) approximations like Becke-Perdew or TPSS, the double-hybrid B2PLYP functional, as well as the corresponding dispersion, including TPSS-D and B2PLYP-D functionals and the wave-function-based spin-component-scaled second-order perturbative Moller-Plesset theory (SCS-MP2), were used. Energy decomposition analysis combined with the analysis of pairwise interfragment correlation energies from Pipek-Mezey localized molecular orbitals in combination with SCS-MP2 led to a clear demonstration of the significant role of dispersion (London) forces in the stabilization of the title adducts, wherein the Os-metal DA bond bears a rather low covalent character. These results plead in favor of a systematic recourse to dispersion including DFT approximations when addressing organometallic and coordination complexes.
一般来说，dative 金属-金属键的概念用于指定电子饱和金属中心与另一个电子缺省的-或不饱和的-金属中心之间的供体-受体（DA）相互作用。这种 DA 键合扩展到配位配合物领域，构成了弱金属-金属相互作用的边缘情况，其中发生在 4d、5d 和其他后过渡金属配合物中的所谓金属亲合相互作用是最有记录和代表性的例子。从一般的角度来看，所谓的 dative 金属-金属键在化学键中的特殊位置源于其假定的共价性质，这与金属亲合相互作用的情况形成对比，后者主要由色散和静电相互作用支持，并且在一定程度上由相对论效应支持。在这项研究中，通过使用最先进的量子化学方法，研究了非桥连 5d-3d Os-Cr 和 5d-5d Os-W 加合物（即（Me（3）P）（CO）（4）Os-M（CO）（5）（M = Cr，W）和（CO）（5）Os-Cr（CO）（5））中金属-金属键的性质。半局部密度泛函理论（DFT）近似，如 Becke-Perdew 或 TPSS、双杂交 B2PLYP 函数以及相应的色散，包括 TPSS-D 和 B2PLYP-D 函数以及基于波函数的自旋分量比例二阶微扰 Moller-Plesset 理论（SCS-MP2），都被使用。能量分解分析结合 Pipek-Mezey 局域分子轨道的成对界面相关能分析与 SCS-MP2 相结合，清楚地证明了色散（伦敦）力在稳定标题加合物中的重要作用，其中 Os-金属 DA 键具有相当低的共价性质。这些结果支持在处理有机金属和配位配合物时系统地使用包括 DFT 近似的色散。
