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 (TeO 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 PhTeI ₃ 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 Tehalide and Teπ system of the phenyl ligand are discussed.