LINEAR AND CYCLIC PLATINUM SIGMA-ACETYLIDE COMPLEXES OF TETRAETHYNYLETHENE

The syntheses of the first organometallic mono- and dinuclear platinum complexes bearing the tetraethynylethene unit as an eta(1)-ligand are reported, Structural characterization of two of the trans sigma-bis(a cetylide) derivatives by X-ray crystallography reveals coplanarity of the acetylenic pi-ligands and indicates possible electronic delocaliza tion across the metal center. This notion is further supported by comp aring the electronic absorption spectra of the platinum-containing com pounds with those of related tetraethynylethene derivatives without me tals. The solid-state structure of a dinuclear complex with two iodopl atinum fragments attached to one set of geminal acetylenes of tetraeth ynylethene was also investigated by X-ray diffraction. Hay coupling of a mononuclear species leads to the incorporation of the sigma-bis(ace tylide) moiety into a diplatinated metallacycle. This macrocyclic comp ound represents a novel structural motif in the design of a transition metal linked carbon network based on tetraethynylethene.