[Tc(NO)Cl 2 (PPh 3 ) 2 (CH 3 CN)] and Its Reactions with 2,2′-Dipyridyl Dichalcogenides

The sparingly soluble technetium(I) complex [Tc I (NO)Cl 2 (PPh 3 ) 2 (CH 3 CN)] ( 1 ) slowly dissolves during reactions with 2,2′-dipyridyl ditelluride, (2-pyTe) 2 , 2,2′-dipyridyl diselenide, (2-pySe) 2 , or 2,2′-dipyridyl disulfide, (2-pyS) 2 , under formation of deeply colored solutions. Blue (Te compound) or red solids (Se compound) of the composition [{Tc I (NO)Cl 2 (PPh 3 ) 2 } 2 {µ 2 -(2-pyE) 2 }], E = Te ( 3 ), Se ( 4 ), precipitate from the reaction solutions upon addition of toluene. They represent the first technetium complexes with dichalcogenides. While [{Tc I (NO)Cl 2 (PPh 3 )} 2 {µ 2 -(2-pyTe) 2 }] ( 3 ) is the sole product, a small amount of a second product, [Tc II (NO)Cl 2 (PPh 3 )(2-pySe)] ( 5 ), was obtained from the respective mother solution of the reaction with the diselenide. From the corresponding reaction between 1 and (2-pyS) 2 , the technetium(II) compound, [Tc II (NO)Cl 2 (PPh 3 )(2-pyS)] ( 6 ), could be isolated exclusively. The products were studied by single-crystal X-ray diffraction and spectroscopic methods including 99 Tc NMR for the technetium(I) products and EPR spectroscopy for the Tc(II) complexes. The experimental results are accompanied by DFT considerations, which help to rationalize the experimental observations.