Comprehensive Computational Study of Decamethyldizincocene Formation. 1. Reaction of ZnR₂ Reagents with Decamethylzincocene

Computational methods were used to study the surprising 2004 synthesis of decamethyldizincocene, Zn₂(η⁵-C₅Me₅)₂, which was the first molecule to have a direct, unbridged bond between two first-row transition metals. The computational results show that the methyl groups of decamethylzincocene, Zn­(η⁵-C₅Me₅)­(η¹-C₅Me₅), affect the transition-state stability of its reaction with ZnEt₂ (or ZnPh₂) through steric hindrance, and this could possibly allow a counter-reaction, the homolytic dissociation of Zn­(η⁵-C₅Me₅)­(η¹-C₅Me₅) into Zn­(η⁵-C₅Me₅)^• and (η¹-C₅Me₅)^•, to occur, and because no such steric hindrance occurs when zincocene, Zn­(η⁵-C₅H₅)­(η¹-C₅H₅), is used as a reactant, its dissociation never occurs regardless of what ZnR₂ reagent is used.