Low-temperature (180 K) crystal structures of tetrakis-μ-(niflumato)di(aqua)dicopper(II) N,N-dimethylformamide and N,N-dimethylacetamide solvates, their EPR properties, and anticonvulsant activities of these and other ternary binuclear Copper(II)niflumat

Two pseudopolymorphs, solvates, of [Cu2II(niflumate)4(H2O)2] of unknown structure were obtained following solution of [Cu2II(niflumate)4(H2O)2] in N,N-dimethylacetamide (DMA) or N,N-dimethylformamide (DMF). Low-temperature crystal structures obtained for these solvates revealed that they were ternary aqua DMA and DMF solvates: [Cu2II(niflumate)4(H2O)2]·4DMAand[Cu2II(niflumate)4(H2O)2]·4DMF. Intermolecular hydrogen bonding interactions account for the formation of these stable DMA and DMF solvates. These pseudopolymorphs contain a centrosymmetric binuclear center with Cu-Cu bond distances ranging from 2.6439(7) to 2.6452(9) Å; the coordination sphere of Cu(II) is characterized by one long Cu-O (water) bond length of 2.128(3)-2.135(3) Å and four short Cu-O (carboxylate) bonds of 1.949(3)-1.977(3) Å. Crystal parameters for the DMA pseudopolymorph: a = 10.372(1), b = 19.625(2), c = 17.967(2) Å, β = 97.40(1)°, V = 3626.8(6) Å3; monoclinic system; space group: P21/a and for the DMF pseudopolymorph: a = 10.125(2), b = 18.647(3), c = 19.616(4) Å, α = 74.38(2)°, β = 88.18(2)°, γ = 79.28(2)°, V = 3504(1) Å3; triclinic system; space group: P1¯. EPR spectra of these solids are identical and show strong antiferromagnetic coupling between the copper atoms, similar to the spectrum obtained for [Cu2II(niflumate)4(DMSO)2]. The [Cu2II(niflumate)4(H2O)2], [Cu2II(niflumate)4(H2O)2]·4DMA, [Cu2II(niflumate)4(H2O)2]·4DMF, [Cu2II(niflumate)4(DMF)2],and[Cu2II(niflumate)4(DMSO)2] evidenced protection against maximal electroshock-induced seizures and Psychomotor seizures at various times after treatment, consistent with the well known antiinflammatory activities of Cu chelates, but failed to protect against Metrazol-induced seizures while evidencing some Rotorod Toxicity consistent with a mechanism of action involving sedative activity.