1D manganese(II) derivatives of an imidazole-substituted nitronyl nitroxide. An approach toward molecular magnetic materials of high dimensionality

Extended linear complexes of manganese(II) with a bis-chelating nitronyl nitroxide ligand, 2-(2-imidazolato)4,4,5,5-tetramethyl-4,5-dihydro-1H-midazolyl-3-oxide-1-oxy (NITIm), have been prepared where metallic and organic spin carriers alternate. Depending on the deprotonating agent, the solvent, and the counteranion, the species [Mn(NITIm)(H2O)(2)]CH3COO, 1, [Mn(NITIm)(DMSO)(2)]BPh4, 2, [Mn(NITIm)(H2O)(ImH)]NO3, 3, and [Mn(NITIm)(NITImH)]ClO4, 4, have been obtained, which differ by the additional ligands completing the metal coordination sphere. Complexes 1-3 are cis isomers and 4 is found as the mer modification; in all compounds, one observes a regular alternation of Lambda and Delta metal environments. Their magnetic properties are similar, with Mn(II)-nitroxide interactions J approximate to -45 cm(-1) (H = -2/S-i. S-j), and they display weak ferromagnetic properties below 5 K. Canting of the manganese ions is responsible for these properties. Relevant crystallographic parameters are as follows: 1, space group Fdd2, a = 16.713(1), b = 40.111(3), c = 9.735(1), Z = 16; 2, space group Pca2(1), a = 30.328(3), b = 13.422(1), c = 9.589(1), Z = 4; 3, space group P2(1)/c, a = 9.787(2), b = 22.973(5), c = 9.671(2), beta = 117.32(3)degrees, Z = 4; 4, space group P2(1)/c, a = 9.761(2), b = 28.668(5), c = 9.941(2), beta = 96.07(3)degrees, Z = 4.