High-Nuclearity Metal Carbonyl Clusters

威斯康星大学麦迪逊分校化学系的Lawrence F.Dahl博士在化学系无机、生物无机和有机金属计划的支持下，继续他对高核度金属羰基簇合物的研究。本项目的主要内容是新的高核度(10个或更多金属原子)同金属和异金属羰基簇合物的合成、X射线结构表征和结构成键分析。一系列钯-羰基-膦簇合物的合成将被优化和扩展，以包括具有不同膦配体的簇合物。这一系列包括59个Pd原子的原子簇，将用质子核磁共振研究以确定是否存在类氢化氢原子。新的Pd-Ni团簇将被合成足够的量来进行物理/化学表征。这些簇将与膦配体反应，以确定配体对金属分离的影响，因为以前这种类型的簇已经显示出令人惊讶的金属有序性。具有28个Pd和12个Pt原子的新型羰基膦-氢化氢簇合物将通过核磁共振和氢-氢交换进一步研究，并通过引入额外的铂和镍原子来合成扩展。将尝试制备一系列具有前所未有的金属骨架的Ni-Pd(或Pt)-Rh(或Ir)羰基氢化物簇合物。这些不寻常的团簇的挑战性表征将通过结合X射线结晶学(CCD面探测器)、电喷雾电离傅立叶变换离子回旋共振质谱仪、X射线荧光、磁化率和核磁共振测量来完成。用包含相对论效应的密度泛函方法对包括18个原子的Ni-Au团簇在内的几个团簇进行了理论研究，以确定Ni-Au键的性质，并将结果与以前使用Fenske-Hall MO模型计算的结果进行比较。最后，将改进和优化合成方法，以制备更多最近发现的用于物理化学研究的38金属Au-Pd-Ni和35金属Cu-Ni团簇。这个项目将增加关于金属原子之间，特别是不同金属类型之间的键的基础知识。大的离散金属团簇也可以作为金属颗粒和表面的模型，有助于我们对表面科学、金属粒子物理和多相催化的理解。多金属钯团簇在设计具有催化、电、磁、光和储氢/同位素分离性能的新材料方面具有潜在的技术重要性。这项工作还推进了最先进的化学分析方法，将这些技术应用于非常苛刻的问题。

Dr. Lawrence F. Dahl of the Department of Chemistry, University of Wisconsin at Madison, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division to continue his studies on high-nuclearity metal carbonyl clusters. The main thrust of this project is the synthesis, X-ray structural characterization, and structure-bonding analysis of new high-nuclearity (10 or more metal atoms) homo- and hetero-metallic carbonyl clusters. The synthesis of a series of palladium-carbonyl-phosphine clusters will be optimized and extended to include clusters with different phosphine ligands. This series, including a cluster with 59 Pd atoms, will be studied by proton NMR to determine if hydrido-like H atoms are present. New Pd-Ni clusters will be synthesized in sufficient amounts to permit physical/chemical characterization. These clusters will be reacted with phosphine ligands to determine the ligand effect on metal segregation since previous clusters of this type have shown a surprising degree of metal order. A novel carbonyl-phosphine-hydrido cluster with 28 Pd and 12 Pt atoms will be further studied by NMR and hydrogen-deuterium exchange, and synthetically extended by incorporation of additional Pt and Ni atoms. The preparation of a series of Ni-Pd(or Pt)-Rh(or Ir) carbonyl-hydrido clusters with unprecedented metal frameworks will be attempted. The challenging characterization of these unusual clusters will be accomplished by the combination of X-ray crystallography (CCD area detector), electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry, X-ray fluorescence, magnetic susceptibility, and NMR measurements. Theoretical studies on several clusters including a 18-atom Ni-Au cluster will be carried out using density functional methods that include relativistic effects in order to determine the nature of the Ni-Au bonds and to compare the results to those of previous calculations using the Fenske-Hall MO model. Finally, synthetic methods will be improved and optimized to prepare larger amounts of recently discovered 38-metal Au-Pd-Ni and 35-metal Cu-Ni clusters for physical-chemical studies. This project will add fundamental knowledge about bonds between metal atoms, especially ones between different metal types. The large discreet metal clusters also can serve as models for metal particles and surfaces and contribute fundamentally to our understanding of surface science, metal-particle physics, and heterogeneous catalysis. The multi-metal palladium clusters have potential technological importance in the design of new materials with useful catalytic, electronic, magnetic, optical, and hydrogen storage/isotope separation properties. This work also advances state-of-the-art methods of chemical analysis by applying these techniques to extraordinarily demanding problems.