Technetium complexes with arylselenolato and aryltellurolato ligands

Reactions of (NBu 4 )[TcOCl 4 ] or [TcCl 3 (PPh 3 ) 2 (CH 3 CN)] with in situ -prepared lithium arylselenolates and -tellurolates give (NBu 4 )[Tc V O(ArE) 4 ] (E = Se, Te; Ar = phenyl) and [Tc III (ArE) 3 (PPh 3 )(CH 3 CN)] (E = Se, Te; Ar = phenyl, 2,6-Me 2 phenyl, 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. The first examples of complexes with technetium-tellurium bonds are reported from reactions of (NBu 4 )[TcOCl 4 ] or [TcCl 3 (PPh 3 )(CH 3 CN)] with lithium aryltellurolates.