Mixed-ligand complexes of technetium IX. Oxidative ligand exchange reactions on tetraphenylarsonium-bis(dithiooxalato)nitridotechnetate(V), (Ph4As)2[TcN(dto)2]. X-ray crystal structure of a further modification of (Ph4As)2[TcN(dto)2]

Abstract (Ph 4 As) 2 [TcN(dto) 2 ] can be prepared starting from TcNCl 4 − or TcNCl 2 (Ph 3 P) 2 . The compound crystallizes in at least two modifications: as well as a triclinic form (S. F. Colmanet and M. F. Mackay, Inorg. Chim. Acta, 147 (1988) 173) a monoclinic one has been found (space group C 2/ c , Z = 4, a = 19.424(3), b = 11.254(2), c = 24.958(3) A, β = 107.68(1)°; R = 0.048). Distances and angles in the complex anions in both modifications are almost identical within experimental error. Oxidation of [TcN(dto) 2 ] 2− by Cl 2 produces the Tc(VI) complex TcNCl 4 − exclusively, whereas during the Br 2 oxidation technetium(VI) intermediates are generated containing mixed Br/dto coordination spheres which can be monitored easily by EPR spectroscopy.