Technetium complexes with arylselenolato and aryltellurolato ligands

Reactions of (NBu₄)[TcOCl₄] or [TcCl₃(PPh₃)₂(CH₃CN)] with in situ-prepared lithium arylselenolates and -tellurolates give (NBu₄)[Tc^VO(ArE)₄] (E = Se, Te; Ar = phenyl) and [Tc^III(ArE)₃(PPh₃)(CH₃CN)] (E = Se, Te; Ar = phenyl, 2,6-Me₂phenyl, mesityl) complexes, respectively. The products contain square-pyramidal (Tc^V compounds) and trigonal bipyramidal (Tc^III complexes) coordinated technetium atoms. Density functional theory calculations indicate that the Tc-chalcogen bonds in the Tc^III compounds have a greater bond order than those in the Tc^V compounds.