Synthesis and characterization of some mono- and dinuclear molybdenum(VI) thiosemicarbazonato complexes

Abstract

Mononuclear molybdenum(VI) complexes of the type [MoO 2{C 6H 4(O)CH:NNC(S)NH 2}(D)] [D = pyridine ( 1d), γ-picoline ( 1c)] and [MoO 2{C 6H 4(O)CH:NNHC(S)NH} (CH 3OH)] · CH 3OH · 1/2bpy ( 1e) have been prepared by the reaction of [MoO 2(C 5H 7O 2) 2] (C 5H 7O 2 = acetylacetonate ion) with salicylaldehyde thiosemicarbazone [C 6H 4(OH)CH:NNC(SH)NH 2] and Lewis base in dry methanol. The dinuclear complex [MoO 2{C 6H 4(O)CH:NNC(S)NH 2}] 2 ( 1b) has been prepared by the reaction of [MoO 2(C 5H 7O 2) 2] with salicylaldehyde thiosemicarbazone [C 6H 4(OH)CH:NNC(SH)NH 2] in dry dichloromethane. In all complexes, except in the case of complex 1e, molybdenum is coordinated by two terminal oxo-oxygen atoms, (O t), by ONS atoms from the salicylaldehyde thiosemicarbazone ligand and by an oxygen atom from the methanol molecule in 1a, and either by a nitrogen atom from γ-picoline in 1c or pyridine in 1d. In [MoO 2{C 6H 4(O)CH:NNHC(S)NH}(CH 3OH)] · CH 3OH · 1/2bipy ( 1e), salicylaldehyde thiosemicarbazone is coordinated to molybdenum through ONN atoms, while the sixth coordination site around the molybdenum atom is completed by the methanol molecule. All complexes have been characterized by means of chemical and thermogravimetric analyses and IR spectroscopy. The molecular structures of complexes 1b, 1c and 1e have been determined by a single crystal X-ray diffraction method.