Bis{cis-[MoO2]} Complexes of 4,6-Diacetyl Resorcinol Bis(hydrazone)and Their Catalytic Application for the Three Components Dynamic Covalent Assembly via Hantzsch Reaction

Four binuclear dioxidomolybdenum(VI) complexes with Schiff base ligands, H(4)dar(bhz)(2) (I), H(4)dar(inh)(2) (II), H(4)dar(nah)(2) (III) and H(4)dar(fah)(2) (IV) (H(2)dar=4,6-diacetyl resorcinol and Hbhz=benzoylhydrazide, Hinh=isonicotinoylhydrazide, Hnah=nicotinoylhydrazide, and Hfah=2-furoylhydrazide) have been prepared by the reaction of ligand with [(MoO2)-O-VI(acac)(2)] (Hacac=acetylacetone) in 1:2 ratio in methanol. Isolated complexes[((MoO2)-O-VI)(2){dar(bhz)(2)}(H2O)(2)] (1), [((MoO2)-O-VI)(2){dar(inh)(2)}(H2O)(2)] (2), [((MoO2)-O-VI)(2){dar(nah)(2)}(H2O)(2)] (3) and [((MoO2)-O-VI)(2){dar(fah)(2)}(H2O)(2)] (4) are characterized by elemental (CHN) analysis, spectral (FT-IR, UV-vis, H-1 and (CNMR)-C-13) and thermogravimetric analysis. Single crystal X-ray diffraction analysis of complexes 1, 2 and 4 confirms their binuclear structure and distorted octahedral geometry around each molybdenum where ligands behave as bis(dibasic tridentate) coordinating through phenolic oxygen, azomethine nitrogen and enolic oxygen atoms of each unit. These complexes have successfully been used as catalyst precursors in solvent as well as solvent free conditions for the one-pot three components (ethylacetoacetate, benzaldehyde and ammonium acetate) dynamic covalent assembly, via Hantzsch reaction using hydrogen peroxide as an oxidant.