Intramolecular d10–d10 Interactions in a Ni6C(CO)9(AuPPh3)4 Bimetallic Nickel–Gold Carbide Carbonyl Cluster

The Ni6C­(CO)9(AuPPh3)4 bimetallic carbide carbonyl cluster was obtained from the reaction of [Ni9C­(CO)17]2– with Au­(PPh3)­Cl. It contains a rare carbon-centered (distorted) Ni6C octahedral core decorated by four Au­(PPh3) fragments. These are μ3-bonded to four contiguous Ni3-triangular faces and display weak intramolecular Au···Au d10–d10 interactions. The cluster has been characterized in the solid state on two different solvato crystals, i.e., Ni6C­(CO)9(AuPPh3)4·THF and Ni6C­(CO)9(AuPPh3)4·THF·0.5C6H14. The two solvates show some interesting differences concerning the weak Au···Au contacts. Density functional theory calculations have demonstrated that the presence of the two isomers is related to solid-state packing effects and not to the existence of two double minima in the potential energy surface. This, in turn, confirms that Au···Au d10–d10 interactions are rather soft and thus influenced also by weak van der Waals forces because of the interaction of the cluster with the cocrystallized solvent molecules.六镍碳基九羰基四(三苯基膦合金)双金属羰基簇合物由[Ni₉C(CO)₁₇]²⁻与Au(PPh₃)Cl反应制得。该簇拥有罕见的以碳为中心（畸变）的六镍碳八面体骨架，表面修饰有四个Au(PPh₃)配体片段。这些配体片段以μ₃-桥联配位模式结合至四个连续的Ni₃三角形面，并展现出弱的分子内Au···Au d¹⁰-d¹⁰相互作用。 该簇已通过两种不同溶剂化晶体完成固态表征，分别为Ni₆C(CO)₉(AuPPh₃)₄·四氢呋喃（THF）以及Ni₆C(CO)₉(AuPPh₃)₄·四氢呋喃·0.5己烷。这两种溶剂化物在弱Au···Au接触特征上存在若干值得关注的差异。 密度泛函理论（Density Functional Theory, DFT）计算表明，两种异构体的存在与固态堆积效应相关，而非源于势能面上存在两个双极小值。该结论进一步证实，Au···Au d¹⁰-d¹⁰相互作用属于典型的软相互作用，因此会因簇合物与共结晶溶剂分子间的相互作用，受到弱范德华力的影响。