Dioxidomolybdenum(VI) complexes with isoniazid-related hydrazones: Solution-based, mechanochemical and UV-light assisted deprotonation

Abstract

Synthesis of the dioxidomolybdenum(VI) complexes [MoO2(HLR)(MeOH)]Cl (1-3) was carried out by using MoO2Cl2 and the corresponding ONO aroylhydrazone ligand H2LR (ligand H2LR is salicylaldehyde isonicotinoylhydrazone (H2LSIH), 2-hydroxy-naphthaldehyde isonicotinoylhydrazone (H2LNIH), or p-(N,N′-diethylamino)salicylaldehyde isonicotinoylhydrazone (H2LEt2NSIH) in methanol. Compounds [MoO2(HLR)(H2O)]Cl (1a-3a) were obtained upon exposure of the corresponding mononuclear complexes 1-3 to moisture. Deprotonation of the mononuclear complexes 1-3 was performed by using Et3N as a base (by the conventional solution based-method and by the mechanochemical approach) as well as by UV-light assisted reactions yielding [MoO2(LSIH)(MeOH)] (4), [MoO2(LNIH)(MeOH)] (5) and [MoO2(LEt2NSIH)]n (6), respectively. Crystal and molecular structures of all complexes were determined by the single crystal X-ray diffraction method. The complexes were further characterized by elemental analysis, IR spectroscopy, TG analysis, one- and two-dimensional NMR spectroscopy and powder X-ray diffraction.