STRUCTURE AND MAGNETIC-PROPERTIES OF MANGANESE(II) CARBOXYLATE CHAINS WITH NITRONYL NITROXIDES AND THEIR REDUCED AMIDINO OXIDE DERIVATIVES - FROM RANDOM-EXCHANGE ONE-DIMENSIONAL TO 2-DIMENSIONAL MAGNETIC-MATERIALS

Two compounds of formula Mn(pfpr)2(NITMe) (I) and [Mn(pfpr)2]2(NITMe)(IMHMe) (II), respectively, where pfpr = pentafluoropropionate, NITMe = 2,4,4,5,5-pentamethyl-4,5-dihydro-lH-imidazolyl-l-oxyl 3-oxide, and IMHMe = 2,4,4,5,5-pentamethyl-4,5-dihydroimidazole 3-oxide, have been synthesized. The latter crystallizes in the monoclinic P21/c space group with a = 13.898 (3) Å, b = 19.089 (4) Å, c = 7.867 (3) Å, β = 94.90 (2)°, R = 0.052, and Z = 4. The structure consists of manganese carboxylate chains that have as additional bridging ligands NITMe and IMHMe molecules randomly distributed along the chains. Hydrogen bonds between neighboring pairs of NITMe and IMHMe molecules connect the chains in puckered planes perpendicular to a. The magnetic properties of [Mn(pfpr)2]2(NITMe)(IMHMe) are consistent with a random-exchange one-dimensional model, while those of Mn(pfpr)2(NITMe) indicate a two-dimensional system with antiferromagnetic interactions between ferrimagnetic chains. The magnetic properties suggest that the crystal structure of I is similar to that of II with the hydrogen bonds replaced by longer contacts between noncoordinated NO groups of the radicals. © 1990, American Chemical Society. All rights reserved.