Structure and Conjugation Study of Organometallic [4]Radialenes of Group 4 Metallocenes. Synthesis of Zirconium [4]Radialene

The first [4]­radialene complex of zirconocene 1Zr-Ph was obtained by the reaction of Negishi’s reagent with 1,4-diphenylbutadiyne. The structure of 1Zr-Ph has been determined by X-ray diffraction. In addition, organometallic [4]­radialenes of group 4 metallocenes were also studied with Raman spectroscopy and density functional theory calculations. The theoretical study illustrates the thermodynamic stability, electronic structure, and conjugation/aromaticity of organometallic radialenes with Ti, Zr, Hf, and various substituents.