We investigate the structure of copper formate and deuterated copper formate clusters using infrared multiple photon dissociation in combination with quantum chemical calculations. Symmetric and asymmetric C–O stretching vibrations along with C–H/C–D stretching vibrations were characterized. Fermi interactions between the C–H stretch and likely a C–O combination band and/or the overtone of a C–H in-plane bending motion have been confirmed by deuteration. The spectra reveal a strong dependence on the monodentate or bidentate binding motif of the formate ligands. Many minima are energetically accessible on the potential energy surface through rotation of the monodentate formate ligands into several almost isoenergetic local minima. While the C–H/C–D stretching vibration is heavily influenced by the charge distribution in the cluster, the C–O vibrations are largely unaffected. The C–H stretch region is not very diagnostic due to a variety of possible Fermi resonances, which also depend on the charge distribution at the formate ligand. Deuteration yields unperturbed spectra in the C–D stretch region and reveals characteristic shifts of the C–D stretching mode for the different binding motifs, with a strong dependence of the band position on the oxidation state of the copper center. The observed bands are compared with formate adsorbed on copper surfaces from the literature.

中文翻译：

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阴离子甲酸铜簇的红外多光子解离光谱

我们使用红外多光子解离结合量子化学计算研究了甲酸铜和氘化甲酸铜簇的结构。对对称和不对称的C–O拉伸振动以及C–H / C–D拉伸振动进行了表征。氘证实了CH延伸与可能的CO组合带和/或CH平面弯曲运动的泛音之间的费米相互作用。光谱显示出强烈依赖于甲酸酯配体的单齿或双齿结合基序。通过将单齿甲酸酯配体旋转成几个几乎等能量的局部极小值，可在势能面上从能量上接近许多极小值。尽管C–H / C–D拉伸振动受到簇中电荷分布的严重影响，C–O振动在很大程度上不受影响。由于各种可能的费米共振，C–H延伸区的诊断性不强，这也取决于甲酸配体上的电荷分布。氘化在C–D拉伸区域产生不受干扰的光谱，并揭示了不同结合基序的C–D拉伸模式的特征性位移，其中带位置强烈依赖于铜中心的氧化态。将观察到的谱带与文献中吸附在铜表面的甲酸盐进行比较。氘化在C–D拉伸区域产生不受干扰的光谱，并揭示了不同结合基序的C–D拉伸模式的特征性位移，其中带位置强烈依赖于铜中心的氧化态。将观察到的谱带与文献中吸附在铜表面的甲酸盐进行比较。氘化在C–D拉伸区域产生不受干扰的光谱，并揭示了不同结合基序的C–D拉伸模式的特征性位移，其中带位置强烈依赖于铜中心的氧化态。将观察到的谱带与文献中吸附在铜表面的甲酸盐进行比较。