Three tetracoordinate Co(ii) complexes [Co(biq)X2] (X = Cl, Br, I) with easy-plane magnetic anisotropy as field-induced single-molecule magnets. Issue 40 (22nd September 2015)

• Record Type: Journal Article
• Authors: Smolko, L.; Černák, J.; Dušek, M.; Miklovič, J.; Titiš, J.; Boča, R.
• Is Part Of: Dalton transactions. Volume 44:Issue 40(2015)
• Page Start: 17565
• Page End: 17571
• Publication Date: 2015-09-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c5dt02827b
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Three mononuclear complexes [Co II (biq)X2 ] (biq = 2, 2′-biquinoline; X = Cl, Br, I) possess a sizable magnetic anisotropy, and they display a superparamagnetic behaviour in an applied external field that culminates between B DC = 0.2–0.3 T. Abstract : Three mononuclear complexes [Co(biq)X2 ] (biq = 2, 2′-biquinoline; X = Cl, Br, I) were prepared by a solvothermal method and characterized by single-crystal X-ray diffraction. In all three complexes the Co(ii ) atom is tetrahedrally coordinated by one biq ligand bonded in a chelate manner and two halogenido ligands. Hydrogen bonding interactions (C–H⋯X) along with the π–π interactions contribute to the stability of the formed packing. Magnetic measurements as well as ab initio calculations revealed that the complexes possess a sizable easy-plane magnetic anisotropy ( D > 0). They display a superparamagnetic behaviour in an applied external field that culminates between B DC = 0.2–0.3 T. Two relaxation processes are observed; the faster can be analysed in terms of the direct and Orbach processes yielding U / k B = 42.6 K and τ 0 = 1.9 × 10 −10 s for X = Cl, U / k B = 39.6 K and τ 0 = 1.2 × 10 −10 s for X = Br and U / k B = 57.0 K and τ 0 = 3.2 × 10 −13 s for X = I at B DC = 0.2 T.