Doubly phenoxide-bridged binuclear copper(II) complexes with ono tridentate schiff base ligand: Synthesis, structural, magnetic and theoretical studies. (28th January 2015)

• Record Type: Journal Article
• Authors: Novoa, Néstor; Justaud, Frédéric; Hamon, Paul; Roisnel, Thierry; Cador, Olivier; Le Guennic, Boris; Manzur, Carolina; Carrillo, David; Hamon, Jean-René
• Is Part Of: Polyhedron. Volume 86(2015)
• Page Start: 81
• Page End: 88
• Publication Date: 2015-01-28
• Subjects: Copper(II) -- ONO Tridentate Schiff base ligand -- Magnetic properties -- Structure determination -- Ab initio calculation; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2014.05.032
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Reactions of tridentate ONO-donor Schiff base ligand H2 L, derived from the condensation of 1-anisyl-1, 3-butanedione and 2-aminophenol, with Cu(NO3 )2 ·3H2 O afford two doubly phenoxo bridged di-copper(II) complexes: [Cu2 L2 ] and [(py- t Bu)2 Cu2 L2 ] depending on the nitrogenous base used. [Cu2 L2 ] shows a strong antiferromagnetic coupling ( J = −397 cm −1 ). Abstract: The tridentate ONO-donor Schiff base ligand H2 L, derived from the condensation of 1-anisyl-1, 3-butanedione and 2-aminophenol, was generated in situ and reacted with Cu(NO3 )2 ·3H2 O to yield two doubly phenoxo bridged di-copper(II) complexes depending on the nitrogenous base used. [Cu2 L2 ] (1 ) is obtained in 85% and 75% yield in the presence of pyridine or 4-picoline, respectively, and [(py- t Bu)2 Cu2 L2 ] (2 ) is isolated in 75% yield in the presence of 4- tert -butylpyridine. Compounds1 and2 were characterized in the solid-state by elemental analysis and FT-IR spectroscopy. Single crystal X-ray diffraction study reveals that in1 the two four-coordinated copper atoms adopt a square planar geometry, whereas in2 each Cu(II) metal ion shows a five coordinate square pyramidal (ONO, N + O) geometry. In each dimer, two μ-phenolic oxygen atoms bridge the two half-units forming a planar Cu2 O2 core. EPR studies in fluid solutions indicate that the dimeric structure of1 and2 is destroyed upon dissolution. In the solid-state, 1 is EPR silent, whereas2 presents an unresolved broad resonance (Δ H peak-to-peak = 71.5 G) with g = 2.071 at 298 K, along with the triplet state ( S = 1) signature at g = 4.181. Variable temperature (2–300 K) magnetic susceptibility measurements exhibit strong antiferromagnetic interactions between the Cu(II) centers with a J value of −397 cm −1 for1, while no interaction operates between the two spins localized on Cu(II) metal ions in2 . Ab initio calculations were also performed to supplement the experimental results.