LINEAR-CHAIN GADOLINIUM(III) NITRONYL NITROXIDE COMPLEXES WITH DOMINANT NEXT-NEAREST-NEIGHBOR MAGNETIC-INTERACTIONS

Gd(hfac)3NITiPr (hfac = hexafluoroacetylacetonate; NITiPr = 2-isopropyl–4,4,5,5-tetramethyl-4,5-dihyro-lH-imidazolyl-l-oxyl 3-oxide) crystallizes in the monoclinic space group P21/n with cell parameters a = 11.916 (1) Å, b = 17.625 (9) Å, c = 18.055 (1) Å, β = 96.98 (1)°, V= 3763.82 Å3, and Z = 4. The structure refinement converged to R = 0.086. The molecular structure of the complex consists of linear chains made up by gadolinium(III) ions bridged by nitronyl nitroxide radicals. The magnetic properties of this compound and of other structurally strictly related lanthanide nitronyl nitroxide complexes are discussed according to a model in which the next-nearest-neighbor interactions are explicitly taken into account. For appropriate values of the exchange parameters the ground state corresponds to a two-spins-up, two-spins-down configuration, which justifies the low effective magnetic moment observed at low temperature. © 1990, American Chemical Society. All rights reserved.