Radial (tetracyclopentadienyl)cyclobutadiene pentametals

Radial (tetracyclopentadienyl)cyclobutadiene pentametals have been synthesized by the Pd-catalyzed coupling of cyclopentadienyltin or of (CpM)zinc reagents with (tetraiodocyclobutadiene)iron(tricabonyl). X-ray structural and NMR data reveal that, while these arrays are crowded, the substituents enjoy considerable rotational freedom.The method constitutes a significant complement to currently existing strategies for the construction of persubstituted cyclobutadiene complexes.

Radial (tetracyclopentadienyl)cyclobutadiene pentametals have been synthesized by the Pd-catalyzed coupling of cyclopentadienyltin or of (CpM)zinc reagents with (tetraiodocyclobutadiene)iron(tricabonyl). X-ray structural and NMR data reveal that, while these arrays are crowded, the substituents enjoy considerable rotational freedom.The method constitutes a significant complement to currently existing strategies for the construction of persubstituted cyclobutadiene complexes.Figure optionsDownload as PowerPoint slideResearch highlights
► Pd-catalyzes the four-fold coupling of cyclopentadienyl metals with (tetraiodocyclobutadiene)iron(tricabonyl).
► Radial tetracyclopentadienyl)cyclobutadiene pentametals represent crowded arrays.
► Despite steric crowding, the substituents in radial (tetracyclopentadienyl)cyclobutadiene pentametals enjoy considerable rotational freedom.