Phenyltellurium halide complexes of iron cyclopentadienyl dicarbonyl: Synthesis and molecular structures of CpFe(CO)2TePh, CpFe(CO) 2TeBr2Ph, CpFe(CO)2TeBrPh(μ-Br)Br 3TePh, and PhTeI3(C4H8O)

The bromination of CpFe(CO)2TePh (I) affords the monomeric complex CpFe(CO)2TePhBr2 (II) as the major product and crystals (III), being a cocrystallizate of complexes II and CpFe(CO)2TeBrPh(μ-Br)TePhBr3 (IIIA). Complex IIIA contains a PhTeBr3 molecule, which is weakly bound because of the lone electron pair (LEP) of the bridging bromine atom of molecule II. An analogous weak interaction with the LEP of oxygen in tetrahydrofuran (Te…O 2.893 Å) is observed in the PhTeI3(THF) adduct (IV), which is a dimer with two bridging iodine atoms and can be obtained by the crystallization of PhTeI3 from THF. According to the X-ray diffraction data, the Fe-Te distances in compounds II and IIIA (on the average, 2.5 Å) differ slightly and are similarly shortened by 0.2 Å compared to the sum of the covalent radii of iron and tellurium. The secondary interactions Te…halide and Te…π system of the phenyl ligand are discussed.