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

Abstract

Synthesis of the dioxidomolybdenum(VI) complexes [MoO₂(HL^R)(MeOH)]Cl (1–3) was carried out by using MoO₂Cl₂ and the corresponding ONO aroylhydrazone ligand H₂L^R (ligand H₂L^R is salicylaldehyde isonicotinoylhydrazone (H₂L^SIH), 2-hydroxy-naphthaldehyde isonicotinoylhydrazone (H₂L^NIH), or p-(N,N′-diethylamino)salicylaldehyde isonicotinoylhydrazone (H₂L^Et₂NSIH) in methanol. Compounds [MoO₂(HL^R)(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(L^SIH)(MeOH)] (4), [MoO₂(L^NIH)(MeOH)] (5) and [MoO₂(L^Et₂NSIH)]_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.