Photochemical synthesis of a zirconium cyclobutadienyl complex

Abstract

Photolysis of (^MePMP^Me)₂ZrBn₂ (^MePMP^Me = 3,5-dimethyl-2-(2-pyridyl)pyrrolide) in the presence of diphenylacetylene yields the first η⁴-cyclobutadienyl zirconium complex, (^MePMP^Me)₂Zr(η⁴-C₄Ph₄), through formal [2+2] cycloaddition of two alkynes at a putative low-valent zirconium intermediate. This unique reactivity expands the scope of alkyne coupling reactions at low-valent zirconium centers that traditionally produce zirconacyclopentadienes.