Dioxomolybdenum(VI) complexes with 2-((2-(pyridin-2-yl)hydrazono)methyl)phenol and its derivatives

Dioxomolybdenum(VI) complexes having the general formula cis-[MoO2(OMe)(Ln)] (1–6) with the tridentate 2-((2-(pyridin-2-yl)hydrazono)methyl)phenol and its substituted derivatives (HLn, n = 1–6) have been synthesized. Elemental analysis and various spectroscopic (IR, UV–Vis, 1H NMR and fluorescence) measurements have been used for the characterization of the complexes. X-ray crystal structures of all the complexes, except for one, have been determined. In each of these analogous complexes, the metal centre is in a distorted octahedral N2O4 coordination sphere assembled by the meridionally spanning pyridine-N, azomethine-N and phenolate-O donor (Ln)−, the methoxo-O and the two mutually cis oriented oxo groups. In the crystal, the complex molecules are involved in intermolecular N–H⋯O hydrogen bonding interactions involving the hydrazine NH and the metal coordinated methoxo-O. In four structures, discrete dimeric units are formed through a pair of reciprocal N–H⋯O hydrogen bonds, while N–H⋯O bridged molecules form a linear one-dimensional polymeric assembly in the fifth structure.

The syntheses, physical properties and X-ray structures of dioxomolybdenum(VI) complexes with 2-((2-(pyridin-2-yl)hydrazono)methyl)phenol and its substituted derivatives (HLn (n = 1–6)) are described. The metal center in these complexes of formula cis-[MoO2(OMe)(Ln)] (1–6) is in a distorted octahedral N2O4 coordination sphere. In the crystal, the N–H⋯O hydrogen bond directed self-assembly of the complex molecules leads to a centrosymmetric dimeric structure for all but one complex, where an infinite chain structure is formed.Figure optionsDownload as PowerPoint slideHighlights
► Complexes of cis-{MoO2}2+ with tridentate 2-pyridylhydrazones were synthesized.
► All the complexes were characterized by CHN analysis, spectroscopy and X-ray crystallography.
► The diamagnetic complexes have distorted octahedral MoN2O4 coordination spheres.
► Intermolecular N–H⋯O hydrogen bond assisted self-assembly patterns are reported.