The Solvent Cage Effect in Organometallic Chemistry

这个名为“有机金属化学中的溶剂笼效应”的项目将由俄勒冈大学的Thomas W. Koenig和David R. Tyler进行，由无机、生物无机和有机金属化学项目资助。这项研究将考察有机金属自由基在溶剂笼中的命运。这项研究的结果有望提高对有机金属自由基反应性的认识，从而更好地理解许多有机金属反应发生的机制。研究将对由选定的前体分子可逆和不可逆形成的笼状自由基对进行。可逆形成的笼状对将通过金属-金属或金属-碳键的热分解产生，例如在八羰基双（三苯基膦）二锰(0)中。不可逆形成的笼状对将由消除中间原子或分子的双金属配合物光解产生，例如二（四羰基钴）汞，其中汞原子作为钴基团之间的小间隔分子被消除。除了增加对自由基反应性的了解外，具体的目标是：确定有机金属配合物的键解离能的大幅度提高值；确定笼型效率，即笼型组合与自由基笼型逸出的比较；考察了自由基的空间尺寸、质量以及溶剂粘度对笼型效率的影响。

This project titled "The Solvent Cage Effect in Organometallic Chemistry" will be carried out by Thomas W. Koenig and David R. Tyler of the University of Oregon and is funded within the Inorganic, Bioinorganic and Organometallic Chemistry Program. The research will examine the fate of organometallic radicals in a solvent cage. The results of this study are expected to lead to enhanced knowledge of the reactivity of organometallic radicals and thus a greater understanding of the mechanism by which many organometallic reactions occur. Studies will be carried out on cage radical pairs that are formed both reversibly and irreversibly from selected precursor molecules. The reversibly formed cage pairs will be generated by thermolysis of metal-metal or metal-carbon bonds, such as in octacarbonylbis(triphenylphosphine)dimanganese(0). The irreversibly formed cage pairs will be generated by photolysis of dimetallic complexes which eliminate an intervening atom or molecule, such as bis(tetracarbonylcobalt)mercury in which the mercury atom is eliminated as the small spacer molecule between the cobalt groups. Specific goals in addition to the increased understanding of radical reactivity are: determining substantially improved values of bond dissociation energies for organometallic complexes; determining the cage efficiency, i.e., cage combination compared to cage escape of radicals; and assessing the effects of steric size and mass of the radical as well as the viscosity of the solvent on the cage efficiency.