Synthesis, Crystal Structures and Catalytic Property of Dioxomolybdenum(VI) and Nickel(II) Complexes Derived from bis-Schiff Bases

Abstract

A new mononuclear dioxomolybdenum(VI) complex, [MoO2L1], and a new linear trinuclear nickel(II) complex, [Ni{NiL2(μ1-η1:η0-OAc)(μ2-η1:η1-OAc)}2]·H2O, where L1 is the dianionic form of N,N’-bis(5-fluorosalicylidene)-1,3-propanediamine (H2L1), L2 is the dianionic form of N,N’-bis(5-fluoro-2-hydroxybenzylidene)-2-hydroxy-1,3-propanediamine (H2L2), have been synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray determination. The Mo atom in the molybdenum complex is coordinated by four donor atoms of the Schiff base ligand, and two oxo groups, forming an octahedral coordination. In the nickel complex, there are three bridges across the Ni-Ni atom pairs, involving two phenolate O atoms of a Schiff base ligand, and an O–C–O moiety of a μ2-η1:η1-OAc group. The central Ni atom is located on an inversion center and has octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and two O atoms from two μ2-η1:η1-OAc ligands in the axial positions. The coordination around the terminal Ni atoms is also octahedral, with two imino N and two phenolate O atoms from a Schiff base ligand defining the equatorial plane, and with two O atoms respectively from a μ1-η1:η0-OAc and a μ2-η1:η1-OAc ligands occupying the axial positions. The molybdenum complex has excellent catalytic property for sulfoxidation reactions.

Keywords

• Dioxomolybdenum complex
• nickel complex
• Schiff base
• Crystal structure
• Sulfoxidation