Valence-inverted reactivity (VIR) is discovered here through high-level computations of excited states of Ni(II) complexes that are generated by triplet energy transfer. For example, the so-generated 3[(Ar)(bpy)NiII(Br)] species possesses a valence-inverted occupancy, dxy1dxz1dx2–y22, wherein the uppermost dx2–y2 orbital is metal–ligand antibonding. This state promotes C–H bond activation of THF and its cross-coupling to the aryl ligand. Thus, due to the metal–ligand antibonding character of dx2–y2, the dxy1dx2–y22 subshell opens a Ni-coordination site by shifting the bidentate bipyridine ligand to monodentate plus a dangling pyridine. The tricoordinate Ni(II) intermediate inserts into a C–H bond of THF, transfers a proton to the dangling pyridine moiety, and eventually generates an arylated THF by reductive-coupling. The calculated high kinetic isotope effect is in accord with experiment, both revealing C–H activation. The VIR pattern is novel, its cross-coupling reaction is highly useful, and it is generally expected to occur in other d8 complexes.

中文翻译：

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镍 (II) 配合物的化合价反转状态执行简便的 C-H 键活化

通过对由三重态能量转移产生的 Ni(II) 配合物的激发态进行高级计算，发现了反价反应性 (VIR)。例如，如此生成的3 [(Ar)(bpy)Ni II (Br)] 物种具有反价占有率 d xy 1 d xz 1 d x 2 –y 2 2，其中最上面的 d x 2 – y 2轨道是金属-配体反键合。这种状态促进了 THF 的 C-H 键活化及其与芳基配体的交叉偶联。因此，由于 d x 2 –y 2的金属-配体反键合特性, d xy 1 d x 2 –y 2 2亚壳通过将二齿联吡啶配体转变为单齿加悬挂吡啶来打开一个 Ni 配位位点。三配位 Ni(II) 中间体插入 THF 的 C-H 键，将质子转移到悬挂的吡啶部分，最终通过还原偶联生成芳基化 THF。计算的高动力学同位素效应与实验一致，均显示 C-H 活化。VIR模式是新颖的，它的交叉偶联反应非常有用，通常预计会发生在其他d 8配合物中。