The initial use of di-2-pyridyl ketone oxime [(py)(2)CNOH] in iron(III) carboxylate chemistry has yielded the tetranuclear complex [Fe4O2Cl2(O2CMe)(2) {(py)(2)CNO}(4)] (1). Compound 1 can be synthesized either by the 1: 2: 1 molar ratio reaction between Fe-III, MeCO2-, and (py)(2)CNOH (complex 1a) or by the 1: 3 molar ratio reaction between [Fe3O(O2CMe)(6)(H2O)(3)] Cl and (py)(2)CNOH (complex 1b). The presence of N-3(-) in both reaction mixtures has afforded the tetranuclear complex [Fe4O2(N-3)(2)(O2CMe)(2) {(py)(2)CNO}(4)] (2), which can be alternatively synthesized by the reaction of 1 with N-3(-). Compound 1a crystallizes in the tetragonal space group I4 with (at 25 degrees C) a = 35.06(2) angstrom, b = 35.06(2) angstrom, c = 13.255(6) angstrom, V = 16293(2) angstrom(3), and Z = 8. Compound 1b crystallizes in the monoclinic space group P2(1)/c with (at 25 degrees C) a = 22.577(7) angstrom, b = 17.078(6) angstrom, c = 17.394(6) beta = 93.50(1), V = 6694(4) angstrom(3), and Z = 4. Compound 2 crystallizes in the triclinic space group P1 with (at 25 degrees C) a = 13.658(9) angstrom, b = 15.815(9) angstrom, c = 17.29(1) angstrom, alpha = 97.08(3)degrees, beta = 98.55(3)degrees, gamma = 112.12(3)degrees, V = 3355(4) angstrom(3), and Z = 2. The structures of 1 and 2 contain the [Fe-4(mu(3)- O)(2)](8+) core comprising four FeIII ions in a "butterfly" disposition and two A(3)-O2- ions, each bridging three FeIII ions forming the "wings" of the "butterfly". The Mossbauer spectra of 1b and 2 consist of composite quadrupole-split doublets, with parameters typical for high-spin Fe-III in octahedral environments. Magnetic susceptibility measurements on 1a revealed antiferromagnetic interactions between the S = 5/2 ferric ions, with best-fit parameters being J(wb) = -40.2 cm(-1) and J(bb) = -59.4 cm(-1) (H = -2 Sigma J(i)J(i)) for wingtip-body and body-body interactions, respectively, yielding an S) 1 ground state. Both wingtip-body and body-body interactions are well determined.