title: Syntheses, crystal engineering, and magnetic property of a dicyanamide bridged three-dimensional manganese(II)-nitronyl nitroxide coordination polymer derived from a new radical.
abstract: Syntheses, structural characterization, crystal engineering, and variable-temperature magnetic study at fixed field strength of a novel dicyanamide bridged three-dimensional manganese(II)-nitronyl nitroxide compound, [Mn(II)(NIT-tz)(dca)(2)] (1), (NIT-tz = 2-(2-thiazole)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy-3-oxide, a new Ullman type radical) have been described. The compound crystallizes in the orthorhombic P2(1)2(1)2(1) space group with the following unit cell parameters: a = 11.015(2) A, b = 12.6134(14) A, c = 13.7652(9) A, and Z = 4. In this complex, the radical behaves as a bidentate chelating ligand, while four single end-to-end dicyanamide (dca) units construct the three-dimensional structure. Inside the structure, there exist diamond-shaped channels, spiral networks, and helical chains. Variable-temperature (5-300 K, 1 T) magnetic susceptibility data reveal the existence of antiferromagnetic interaction in this molecule. The magnetic behavior is explained by considering the exchange-coupled manganese(II)-radical system, which is subjected to the Mn(II)-dca-Mn(II) intermolecular interactions (H = -2JS(1).S(2) - 2zJ'<S>S). The least-squares fitting of the data results J = -73 cm(-)(1), g = 1.99, and J' = -0.17 cm(-)(1) (z = 4).
authors.affiliation: Department of Chemistry, Tamkang University, Tamsui, Taiwan 25137.
authors.forename: Hsin-Huang
authors.initials: HH
authors.lastname: Lin
authors.forename: Sasankasekhar
authors.initials: S
authors.lastname: Mohanta
authors.forename: Chin-Jhan
authors.initials: CJ
authors.lastname: Lee
authors.forename: Ho-Hsiang
authors.initials: HH
authors.lastname: Wei