Syntheses, Structures and Magnetic Properties of Trinuclear CuIIMIICuII (M = Cu, Ni, Co and Fe) and Tetranuclear [2x1+1x 2] CuIIMnII-2CuII Complexes Derived from a Compartmental Ligand: The Schiff Base 3-Methoxysalicylaldehyde Diamine Can also Stabilize a Cocrystal

The present investigation describes syntheses, characterization and studies of the mononuclear compound [(CuLC)-L-II (H2O)] (1), the triangular, trinuclear monophenoxido-bridged compounds [{(CuL)-L-II}(2)Mn-II(H2O)(2)](ClO4)(2)center dot nH(2)O [2 (M = Cu, n = 0), 3 (M = Ni, n = 3), 4 (M = Co, n = 0), 5 (M = Fe, n = 0)] and the tetrametallic self-assembled complex [{(CuLMnII)-L-II(H2O)(3)]-{(CuL)-L-II)(2)](ClO4)(2)center dot H2O (6) derived from compartmental Schiff base ligand, H2L, which is the [2+1] condensation product of 3-methoxysalicylaldehyde and trans-1,2-diaminocyclohexane. Single-crystal X-ray structures of 2, 5 and 6 were determined. Two pairs of terminal center dot center dot center dot central metal ions in the trinuclear cores in 2 and 5 are monophenoxido-bridged. Interestingly, the CuO6 and FeO6 environments have tetragonally compressed octahedral geometries. On the other hand, the structure of 6 reveals that it is a [2X1+1x2] cocrystal of one diphenoxido-bridged dinuclear [(CuLMnII)-L-II(H2O)(3)](2+) dication and two mononuclear [(CuL)-L-II] moieties. Cocrystallization in 6 takes place as a result of water encapsulation. The variable-temperature (2-300 K) magnetic susceptibilities of compounds 2-6 have been measured. The exchange integrals obtained are: the Cu-3(II) compound 2, J = -78.9 cm(-1); the (CuNiCuII)-Ni-II-Cu-II compound 3, J = -22.8 cm(-1); the (CuCoCuII)-Co-II-Cu-II compound 4, J = -7.8 cm(-1); the (CuFeCuII)-Fe-II-Cu-II compound 5, J = -3.0 cm(-1); the (Cu3MnII)-Mn-II compound 6, J = -15.1 cm(-1). The monophenoxido-bridging core in 3 and 4 has been proposed after comparison of the structures and magnetic properties of these two compounds with those of 2, 5 and related other compounds. This paper presents rare examples of monophenoxido-bridged (CuMCuII)-M-II-Cu-II (M = Cu, Ni, Co and Fe) compounds, provides an understanding of the structures from magnetic exchange integrals, and, most importantly, reports on the first example of a cocrystal derived from a 3-methoxysalicylaldehyde diamine compartmental ligand.