Moore David T, Oomens Jos, Eyler John R, Meijer Gerard, von Helden Gert, Ridge Douglas P
FOM Institute for Plasma Physics "Rijnhuizen", Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands.
J Am Chem Soc. 2004 Nov 17;126(45):14726-7. doi: 10.1021/ja0449527.
The first gas-phase vibrational spectra are presented for several anionic iron carbonyl clusters, ranging in size from Fe(CO)4- to Fe5(CO)14- in the CO-stretching region (1600-2100 cm-1). The experimental spectra provide some immediate structural information about the clusters in the form of low-wavenumber (1750-1850 cm-1) bands marking the presence of bridging carbonyl ligands (mu2-COs). Supporting DFT calculations are presented for the smaller clusters (<3 Fe atoms) and give good agreement with the experimental data, allowing structural assignments for these cases. The Fe2(CO)7- spectrum suggests a structure lacking bridging carbonyl ligands, in agreement with the DFT results. For the case of Fe2(CO)8-, there are two possible structures based on the calculations, both with and without bridging carbonyls. The presence of a low-frequency band ( approximately 1770 cm-1) in the experimental spectrum conclusively demonstrates the existence of the bridged form. The ramifications of these data for metal-metal bonding in the clusters are also considered.
首次给出了几种阴离子铁羰基簇合物在CO伸缩振动区域（1600 - 2100 cm⁻¹）的气相振动光谱，这些簇合物的大小从Fe(CO)₄⁻到Fe₅(CO)₁₄⁻不等。实验光谱以低波数（1750 - 1850 cm⁻¹）谱带的形式提供了一些关于簇合物的直接结构信息，这些谱带表明存在桥连羰基配体（μ₂ - CO）。对较小的簇合物（<3个铁原子）进行了支持性的密度泛函理论（DFT）计算，计算结果与实验数据吻合良好，从而可以对这些情况进行结构归属。Fe₂(CO)₇⁻的光谱表明其结构中不存在桥连羰基配体，这与DFT结果一致。对于Fe₂(CO)₈⁻的情况，基于计算有两种可能的结构，一种有桥连羰基，一种没有。实验光谱中低频带（约1770 cm⁻¹）的存在确凿地证明了桥连形式的存在。还考虑了这些数据对簇合物中金属 - 金属键合的影响。
