Cyclodimerization of phenyliodoacetylene with elemental tellurium: New pathway to 1.3-ditellurofulvenes

Thermal reaction between PhCtriple bond; length of mdashCI and powdered Te afforded a mixture of (E)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3-ditellurofulvene (1) and (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1-(diiodo),3-ditellurofulvene (2), which was subsequently reduced to (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3-ditellurofulvene (3). Formation of 1 and 3 as the thermodynamically most stable products has been rationalized using density functional theory (DFT) calculations. Molecular structures of 1–3 were established crystallographically. In the solid state the coordination sphere of both tellurium atoms in 2 is extended by weak intermolecular Te⋯π interactions with the solvate molecule of toluene which completes the pseudo-trigonal bipyramidal coordination geometry around each Te atom and assembles 2 into the chains along the crystallographic c-axis.