Electronic State of a Conducting Single Molecule Magnet Based on Mn-salen Type and Ni-Dithiolene Complexes

The electrochemical oxidation of an acetone solution containing [MnIII (5-MeOsaltmen)(H2O)]2(PF6)2 (5-MeOsaltmen2– = N,N′-(1,1,2,2-tetramethylethylene)bis(5-methoxysalicylideneiminate)) and (NBu4)[Ni(dmit)2] (dmit2– = 2-thioxo-1,3-dithiole-4,5-dithiolate) afforded a hybrid material, [Mn(5-MeOsaltmen)(acetone)]2[Ni(dmit)2]6 (1), in which [Mn2]2+ single-molecule magnets (SMMs) with an S T = 4 ground state and [Ni(dmit)2] n− molecules in a charge-ordered state (n = 0 or 1) are assembled in a layer-by-layer structure. Compound 1 crystallizes in the triclinic space group P1̅ with an inversion center at the midpoint of the Mn···Mn dimer. The [Mn2]2+ unit has a typical nonplanar Mn(III) dimeric core and is structurally consistent with previously reported [Mn2] SMMs. The six [Ni(dmit)2] n− (n = 0 or 1) units have a square-planar coordination geometry, and the charge ordering among them was assigned on the basis of ν(CC) in IR reflectance spectra (1386, 1356, 1327, and 1296 cm–1). The [Mn2]2+ SMM and [Ni(dmit)2] n− units aggregate independently to form hybrid frames. Electronic conductivity measurements revealed that 1 behaved as a semiconductor (ρrt = 2.1 × 10–1 Ω·cm–1, E a = 97 meV) at ambient pressure and as an insulator at 1.7 GPa (ρ1.7GPa = 4.5 Ω·cm–1, E a = 76 meV). Magnetic measurements indicated that the [Mn2]2+ units in 1 behaved as S T = 4 SMMs at low temperatures.