High-spin Mn wheels

The syntheses, structures, and magnetic properties of the complexes [Mn-4(IV) (Mn10Mn2O2II)-Mn-III(OCH3)(12)(tmp)(8)(O2CCH3)(10)]center dot 3Et(2)O (1.3Et(3)O), [(Mn2Mn8Mn22O6)-Mn-IV-Mn-III-O-II(OCH3)(14)(O2CCH3)(16)(tmp)(8)(HIm)(2)]center dot 2CH(3)OH (2.2CH(3)OH), and [(Mn2Mn18Mn2O6II)-Mn-IV-Mn-III-(OCH3)(14)(O2CCH3)(16)(Br-mp)(8)(HIm)(2)]center dot 2C(6)H(14)center dot 5CH(3)OH (3 center dot 2C(6)H(14)center dot 5CH(3)OH) are reported. The unusual wheel-like complexes were prepared by the treatment of [Mn3O(O2CCH3)(6)(Hlm)(3)](O2CCH3) (Hlm = imidazole) with 1,1,1-tris(hydroxymethyl) propane (H(3)tMP) (1 and 2) or 2- (bromomethyl) -2-(hyd roxym ethyl) -1, 3-propanediol (Br-mpH(3)) (3) in the presence of sodium methoxide (NaOCH3, 2, and 3) in CH3OH. Complex 1-3Et(2)O crystallizes in the triclinic space group Mi, while complexes 2-2CH(3)OH and 3 center dot 2C(6)H(14)-5CH(3)OH crystallize in the orthorhombic space group P (1) over bar. Direct current magnetic susceptibility data, collected for 1-3 in the respective 1.8-300 K and 0.1-7 T temperature and magnetic-field ranges, afford spin ground-state values of S = 14 +/- 1 for complex 1 and S = 9 +/- 1 for complexes 2 and 3. Alternating current susceptibility measurements performed on all three complexes in the 1.8-10 K temperature range in a 3.5 G oscillating field at frequencies between 50 and 1000 Hz reveal outof-phase chi(M) signals below approximately 3 K. ngle-crystal hysteresis loop and relaxation measurements confirm single-molecule magnetism behavior.