Syntheses, crystal structures and magnetic properties of a new nitronyl nitroxide radical and its Cu(II) complex

A new compound (NIT-InNO2 = 4,4,5,5-tetramethylimidazoline-2-yl- (2′-chlor-5′-nitrophenyl)-3-oxide-1-oxyl) 1 and its complex (Cu(NIT-mNO2)(hfac)2) 2 have been synthesized and structurally and magnetically characterized. Complex 1 crystallizes in monoclinic, space group P21/n with a = 10.6798(9), b = 11.2705(9), c = 12.9559(10) Å, β = 107.3770(10)°, V = 1488.3(2) Å3, C13H15ClN3O4, Mr = 312.73, Z = 4, Dc = 1.396 g/cm3, μ(MoKa) = 0.276 mm-1, F(000) = 652, the final R = 0.0606 and wR = 0.1773 for 3405 independent reflections with Rint, = 0.0203. The nitronyl nitroxide unit (imidazoline ring) is not coplanar with the phenyl ring with the dihedral angle between them of 55.75°. The compound results in a 1-D zig-zag chain structure by intermolecular H-bond interaction. Compound 2 crystallizes in triclinic, space group P1̄ with a = 10.3699(10), b = 10.6286(11), c = 15.1683(15) Å, a = 77.5330(10), β = 773080(10), γ = 87.3420(10)°, V = 1592.5(3) A3, C23H 17ClF12N3O8Cu, Mr = 790.39, Z = 2, Dc = 1.648 g/cm3, μ(MoKa) = 0.888 mm-1, F(000) = 788, the final R = 0.0793 and wR = 0.2153 for 5794 independent reflections with Aint = 0.0196. The Cu(II) ion is located at a center of symmetry, and each Cu(II) is surrounded by six oxygen atoms at the vertices of a distorted tetragonal octahedron. Four of the six oxygen atoms belong to two hfac ligands and occupy the equatorial coordination sites, while the other two of NIT-mNO2 act as μ-1,5 bridge between the Cu(II) ion, thus forming a 1-D chain structure. The magnetic susceptibility data indicate intermolecular antiferromagnetic interactions between compound 1 and intrachain ferromagnetic behaviors.