Synthesis and reactions of organometallic complexes featuring a doubly-linked dicyclopentadienyl ligand.

摘要

This dissertation presents an overview of synthesis and chemical reactivity of a novel diruthenium complex {lcub}(η5-C₅H ₃)₂(SiMe₂)₂{rcub}Ru₂(CO) ₄ (1) and its derivatives. Complex 1H +, [{lcub}(η5-C₅H₃)₂(SiMe ₂)₂{rcub}Ru₂(CO)₄(μ-H)]+, with a protonated Ru-Ru bond, is deprotonated only very slowly (hours or days) by basic amines and phosphines although the proton in 1H + is acidic thermodynamically. This remarkable kinetic inertness of the bridging proton allows primary and secondary amines to react with 1H+ by attacking the CO ligand to give a formamide and the CO-substituted ruthenium complex {lcub}(η5-C₅H ₃)₂(SiMe₂)₂{rcub}Ru₂(NHR ₁R₂)(CO)₃. We have demonstrated that a CO ligand in the protonated complex {lcub}(η5-C₅H₃) ₂(SiMe₂)₂{rcub}Ru₂(CO)₄(μ-H)] + (1H+−) is the site of reaction with amines because of the high electrophilicity of the CO ligands and the low kinetic acidity of the bridging hydride—a unique combination of kinetic properties that are not found in the Fe and Os analogs. On the other hand, I−, RS− and phosphines add at one of the Ru centers in 1H+, resulting in cleavage of the Ru-H-Ru bond. The final type of addition to 1H + is that exhibited by MeO− and F− , which results in cleavage of Si-C(cyclopentadienyl) bonds. Except for the reaction with F−, all of these types of reactions depend on the presence of the proton on the Ru-Ru bond. The unprotonated (η 5-C₅H₃)₂(SiMe₂)₂ {rcub}Ru₂(CO)₄ (1) undergoes no reactions with these nucleophiles (except F−) under the mild room temperature conditions of these studies. The protonated diruthenium alkene complexes (η5-C₅H₃)₂ (SiMe₂)₂{rcub}Ru₂(CO)₃(η 2-CH₂=CH-R)(μ-H)]+ react with a variety of nucleophiles to give hydrofunctionalized alkenes with predominantly Markovnikov regioselectivity. The dinuclear ruthenium complex {lcub}(η5-C ₅H₃)₂(SiMe₂)₂{rcub}Ru₂(CO) ₄ (1) is a precursor for the synthesis of a variety of new dinuclear ruthenium complexes, in which the bridging (η5-C ₅H₃)₂(SiMe₂)₂ ligand controls the geometry of the final product. Thus, complex 1 reacts with diphenylacetylene to form a series of the unusual ruthenacarbocyclic complexes as major products.