Intriguing binding modes of tetradentate pyridoxal derivatives to molybdenum centre. (8th May 2017)

• Record Type: Journal Article
• Authors: Pisk, Jana; Prugovečki, Biserka; Jednačak, Tomislav; Novak, Predrag; Vrdoljak, Višnja
• Is Part Of: Polyhedron. Volume 127(2017)
• Page Start: 337
• Page End: 344
• Publication Date: 2017-05-08
• Subjects: Pyridoxal -- Molybdenum(VI) complexes -- Tetradentate ligand -- Schiff base -- Bridging ligand; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2017.02.023
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: In this work we have applied mechanochemical synthesis as an elegant pathway for preparation of the pdxen type of ligands. The synthesis and characterization of the mononuclear Mo(VI) complexes with pyridoxal derived ligands Rpy2 en, Rpy2 pren and py2 pren as well as dinuclear complex with bridging ligand H2 py2 en were reported. Abstract: The Schiff base pdxen ligands (H2 py2 en = N, N ′-ethylenebis(pyridoxylideneimine) and H2 py2 pren = N, N ′-prophylenebis(pyridoxylideneimine)) were found to form readily by the mechanochemical synthesis from their corresponding diamine and pyridoxal. Reduction of the Schiff bases with NaBH4 yielded reduced pdxan ligands (H2 Rpy2 en = N, N ′-ethylenebis(pyridoxylamine) and H2 Rpy2 pren = N, N ′-prophylenebis(pyridoxylamine)). A dinuclear molybdenum(VI) complex with the bridging pdxen ligand [{MoO2 }2 ( μ -py2 en)(OMe)2 (MeOH)2 ]⋅ 3MeOH (1⋅3MeOH ), and mononuclear complexes with the pdxen ligand [MoO2 (py2 pren)] (3 ), as well as with the pdxan ligands: [MoO2 (Rpy2 en)] (2 ) and [MoO2 (Rpy2 pren)] (4 ) were prepared and characterized. Significant differences in the coordination of the Schiff base ligands were found as a consequence of chain length and ligand flexibility. Complexes1 –4 were obtained either by the reaction of [MoO2 (acac)2 ] or [Mo(CO)6 ] with the corresponding ligands. Crystal and molecular structures of complexes1⋅3MeOH, 2 and3 were determined by the single crystal X-ray diffraction method. All complexes were characterized by microanalysis, FT-IR, NMR, UV, thermogravimetric analysis and powder X-ray diffraction method.