Issue 1, 2008

Interpretation of the multiple vanadium-oxygen bonds in the central VO(η2-O2)+group. Synthesis, structure, supramolecular interactions and DFT studies for complexes with 2,2′-bipyridine, 1,10-phenanthroline, pyrazinato(1−) and pyrazinamide ligands

Abstract

Neutral peroxovanadium(V) complexes, [VO(O2)(pca)(bpy)] (1), [VO(O2)(pca)(phen)] (2) and [VO(O2)(pic)(pcaa)(H2O)]·H2O (3), were synthesized [2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), pyrazinecarboxamide (pcaa), 2-pyrazinecarboxylic (Hpca) and picolinic (Hpic) acids]. Their X-ray single crystal analysis revealed a distorted pentagonal bipyramidal geometry in all complex molecules. The four “free” coordination sites of the vanadium atoms of the VO(η2-O2)+ moieties in 1 and 2 are occupied by the donor atoms of two bidentate heteroligands. The supramolecular structures of 1 and 2 are exclusively constructed by intermolecular C–H(ar)⋯O hydrogen bonds [dH(H⋯O): 2.292–2.708 Å (1), and 2.260–2.720 Å (2)]. In addition, the structures are stabilized by parallel off-set π–π interactions between the bpy rings resp. non-parallel off-set interactions between the phen rings [centroid distances: 3.7000(1) Å (1), 3.9781(2) and 3.6757(2) Å (2)]. In the molecular structure of 3, pcaa is coordinated in an equatorial position of the bipyramidvia the nitrogen atom of the pyrazine ring, while the aqua ligand is in the apical position. The disordered crystal water molecules are located in 1D channels oriented along the a axis. The intermolecular C–H(ar)⋯O hydrogen bonds in 3 were found within the dH(H⋯O) range 2.409–2.669 Å. The pic ligands are off-set π–π stacked, with centroid distances: 3.6725(3) and 3.8323(3) Å. The DFT orbital calculations and NBO analysis for the VO(η2-O2)+group gave evidence for a triple V[triple bond, length as m-dash]O bond, and showed that the observed cis arrangement of the oxo and peroxo ligands results from the direct interaction between them. Experimental and calculated UV-Vis and IR spectral data are presented.

Graphical abstract: Interpretation of the multiple vanadium-oxygen bonds in the central VO(η2-O2)+group. Synthesis, structure, supramolecular interactions and DFT studies for complexes with 2,2′-bipyridine, 1,10-phenanthroline, pyrazinato(1−) and pyrazinamide ligands

Supplementary files

Article information

Article type
Paper
Submitted
24 Jul 2007
Accepted
09 Oct 2007
First published
24 Oct 2007

Dalton Trans., 2008, 121-130

Interpretation of the multiple vanadium-oxygen bonds in the central VO(η2-O2)+group. Synthesis, structure, supramolecular interactions and DFT studies for complexes with 2,2′-bipyridine, 1,10-phenanthroline, pyrazinato(1−) and pyrazinamide ligands

S. Pacigová, R. Gyepes, J. Tatiersky and M. Sivák, Dalton Trans., 2008, 121 DOI: 10.1039/B711347A

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