A heterometallic [Mn9Ni2] cluster consisting of the [M4(μ3-O)3(μ3-Cl)]n+ cubane and [MnIII3(μ3-O)4]+ “V-shaped” sub-units appearing in the giant [Mn84] and [Mn70] compounds and its [Mn9CoIII2] analogue

Abstract

Two new heterometallic clusters exhibiting related cores, [Mn9Ni2(μ3-Ο)10(μ3-Cl)2(O2CMe)11(py)4(H2O)4]·2H2O (1·2H2O) (py = pyridine) and [Mn9Co2(μ3-Ο)10(μ3-ΟΗ)2(O2CEt)10(EtOH)3(H2O)(py)5](ClO4)2Cl (2) are reported. Compounds 1·2H2O/2 were prepared from reactions of [Mn3O(O2CMe)6(py)3]·py/[Mn3O(O2CEt)6(py)3](ClO4) with MCl2·6H2O (M = Ni2+, Co2+) and (Bun4N)MnO4 in a 1:3:0.1/1:1:0.1 molar ratio in MeCN (15 ml)/MeOH-EtOH (15–0.5 ml) in ∼ 28 %/< 2 % yields, respectively. Their cores consist of two [MnIVMnIII2Mn+(μ3-Ο)3(μ3-X)]m+ cubanes (Mn+ = Ni2+, X = Cl−, m = 5+, 1·2H2O; Mn+ = Co3+, X = OH−, m = 6+, 2) at the terminal positions linked through a central [MnIII3(μ3-Ο)4]+ slightly V-shaped sub-unit. Interestingly, this core has appeared as a fragment in the giant [Mn84] and [Mn70] torus–like single–molecule magnets (SMMs). Magnetism studies of 1·2H2O revealed the presence of competing ferromagnetic and antiferromagnetic exchange interactions leading to a fairly low spin ground state value of ST ≈ 4 or 3 and fully visible out-of-phase ac signals (above 1.8 K) indicative of slow relaxation of the magnetization and SMM behavior.