Mass-selected heteronuclear vanadium-nickel carbonyl anions VNi(CO)_n⁻ (n = 2-6) were investigated by photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to obtain their chemical bonding and intrinsic electronic structure in the gas phase. The calculated energies (adiabatic detachment energies)/vertical detachment energies (VDEs) match well with experimental values: 1.30/1.49, 1.66/1.95, 2.22/2.48, 2.70/2.89, and 2.95/3.15 eV. The VDE value of VNi(CO)_n⁻ increases with an increase of cluster size, implying that the negative electron is stabilized upon the bonding of CO molecules. VNi(CO)₂⁻ consists of one bridging carbonyl and one terminal carbonyl, whose feature is different from MNi(CO)₂⁻ (M = Sc, Y, La, and Ce) with the involvement of one side-on-bonded carbonyl and one terminal CO carbonyl. The building block composed of three bridging carbonyls is favored for VNi(CO)₃⁻, the structure of which persists up to n = 6. The additional CO ligands are preferentially coordinated in the terminal mode to the Ni atom at n = 4 and then to the V atom at n = 5 and 6. The results obtained in this work would provide a molecular-level understanding about chemisorbed CO molecules on alloy surfaces/interfaces, which is important to understand CO molecule activation processes.

中文翻译：

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杂核钒镍羰基阴离子VNi（CO）n-（n = 2-6）的光电子速度图成像光谱和理论研究

质量选择的异核钒-羰基镍阴离子VNI（CO）_ñ ^- （Ñ = 2-6）由光电子速度映射成像光谱和量子化学计算进行了调查，以获得它们的化学键合和本征电子结构在气相中。计算出的能量（绝热分离能）/垂直分离能（VDE）与实验值非常匹配：1.30 / 1.49、1.66 / 1.95、2.22 / 2.48、2.70 / 2.89和2.95 / 3.15 eV。VNI（CO）的VDE价值_ñ ^-增加随着簇大小的，这意味着负电子被在CO分子的键合稳定。VNI（CO）₂ ^-由一个桥接羰基和一个末端羰基，其特征是从不同的中号的Ni（CO）₂ ^- （中号与参与=钪，Y，La和Ce）的一个侧面上键合的羰基和一个末端CO羰。三个桥接的羰基组成的结构单元赞成VNI（CO）₃ ^-其结构，仍然存在高达Ñ = 6.额外的CO配体在配位优先在终端模式与Ni原子Ñ = 4，然后到n处的V原子 分别为5和6。在这项工作中获得的结果将提供有关化学吸附在合金表面/界面上的CO分子的分子水平的理解，这对于理解CO分子的活化过程非常重要。