The homoleptic homodinuclear nickel carbonyl anions Ni₂(CO)_n⁻ (n = 4–6) are mass-selected in the gas phase and examined with anion photoelectron velocity-map imaging spectroscopy combined with density functional calculations. The doubly carbonyl-bridged structures are found to be favorable for Ni₂(CO)_n⁻ (n = 4–6). The nature of Ni–Ni bonding in these complexes is analysed with the aid of a range of state-of-the-art quantum chemistry methods. Despite the absence of direct multiple Ni–Ni bonds, the two nickel atoms in Ni₂(CO)_n⁻ (n = 4–6) complexes are joined by two bridging carbonyl ligands via the sharing three-center two-electron Ni–C–Ni bond in turn to achieve the (16,16), (16,18), and eventually the favored (18,18) configurations.

中文翻译：

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具有双三中心双电子Ni–C–Ni键的不饱和双核均羰基镍羰基阴离子Ni2（CO）n−（n = 4–6）

均配型同双羰基镍的Ni阴离子₂（CO）_ñ ^- （Ñ = 4-6）是大量选择在气相中并用阴离子光电子速度映射成像光谱带密度泛函计算合并的检查。所述双羰基桥连的结构被发现是有利的Ni ₂（CO）_ñ ^- （Ñ = 4-6）。这些配合物中镍-镍键的性质借助一系列最新的量子化学方法进行了分析。尽管没有直接多重镍Ni债券，以Ni两个镍原子₂（CO）_ñ ^- （Ñ= 4–6）复合物由两个桥接的羰基配体通过共享的三中心双电子Ni–C–Ni键相连，依次得到（16,16），（16,18），并最终受到青睐（ 18,18）配置。