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 [Mn-III (5-MeOsaltmen)(H2O)](2)(PF6)(2) (5-MeOsaltmen(2-) = N,N'-(1,1,2,2-tetramethylethylen e)bis (5-methoxysalicylideneiminate)) and (NBu4)[Ni(dmit)(2)] (dmit(2-) = 2-thioxo-1,3-dithiole-4,5-dithiolate) afforded a hybrid material, [Mn(5-MeOsaltmen)(acetone)](2)[Ni(dmit)(2)](6) (1), in which [Mn-2](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 P (1) over bar with an inversion center at the midpoint of the Mn center dot center dot center dot Mn dimer. The [Mn-2](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 v(C=C) in IR reflectance spectra (1386, 1356, 1327, and 1296 cm(-1)). The [Mn-2](2+) SMM and [Ni(dmit)(2)](n-) units aggregate independently to form hybrid frames. Electronic conductivity measurements revealed that 1 behaved as a semiconductor (rho(rt) = 2.1 x 10(-1) Omega.cm(-1), E-a = 97 meV) at ambient pressure and as an insulator at 1.7 GPa (rho(1.7GPa) = 4.5 Omega.cm(-1), E-a = 76 meV). Magnetic measurements indicated that the [Mn-2](2+) units in 1 behaved as S-T = 4 SMMs at low temperatures.