Characterization of the E Isomer of Tetrasubstituted [5]Cumulene and Trapping of the Z Isomer as a Zirconocene Complex

The E isomer of a [5]cumulene derivative, 2,2,9,9-tetramethyl-3,8-diphenyldeca-3,4,5,6,7-pentaene (1), which was previously believed to be unisolable owing to very fast E/Z isomerization, was isolated and structurally characterized. The Z isomer was trapped as the transition-metal complex 5, and the molecular structure was determined. DFT calculations and an electrochemical study on 1 are also described.