Ferromagnetic Spin Ladder System: Stack of Chlorido‐Bridged Dinuclear Copper(II) Complexes with 2‐Methylisothiazol‐3(2H)‐one

Abstract

AbstractA dinuclear copper(II) complex, [{CuIICl(O‐mi)}2(μ‐Cl)2] [mi = 2‐methylisothiazol‐3(2H)‐one], has been synthesized and its molecular structure in the solid state determined by single‐crystal X‐ray analysis. The crystal consists of centrosymmetric dinuclear copper(II) units in which each copper(II) ion is doubly bridged by two chloride ions and has a slightly distorted square‐planar geometry with a terminal chlorido ligand and a terminal mi ligand coordinated through the oxygen atom. The dinuclear units stack one on top of another to form a one‐dimensional two‐leg ladder structure. The magnetic susceptibility of the powder was measured in the temperature range 3.0–302 K. It was found that there are ferromagnetic interactions along the rung (in the same direction of the intramolecule; Jrung = +5.03 ± 0.03 cm–1) and the leg (in the same direction of the intermolecule; Jleg = +1.96 ± 0.02 cm–1) and an antiferromagnetic interaction along the diagonal (Jx = –1.36 ± 0.02 cm–1), the experimental data being fitted by the numerical calculation for a twelve‐site ladder Hamiltonian. In addition, DFT calculations with the UB3LYP functional on the model complex [{CuIICl(O‐mi)}2(μ‐Cl)2] gave an intramolecular magnetic coupling constant J = +28.6 cm–1 and indicated that the spin‐density distribution on O in mi is less than that on the terminal Cl. We conclude that the O‐donor ligand at the terminal position plays an essential role in the emerging intramolecular ferromagnetic interaction.