The reactions of [Mn3O(O2CCCl3) 6(H2O)3] with 1-phenyl-3-(2-pyridyl)propane-1, 3-dione (HL1) and 1-(2-pyridly)-3-(p-tolyl)propane-1,3-dione (HL 2) in CH2Cl2 afford the mixed-valence Mn II2MnIII2 tetranuclear complexes [Mn4O-(O2CCCl3)6(L1) 2] (1) and [Mn4O(O2CCCl3) 6L22] (2), respectively. Similar reactions employing [Mn3O(O2CPh)6(H2O)(py) 2] with HL1 and HL2 give the Mn II3MnIII3 hexanuclear complexes [Mn6O2(O2CPh)8(L1) 3] (3) and [Mn6O2(O2CPh) 8L32] (4), respectively. Complexes 1·2CH2Cl2, 2·2CH2Cl 2·H2O, 3·1.5CH2Cl 2·Et2O·H2O, and 4·2CH 2Cl2 crystallize in the triclinic space group P1, monoclinic space group P21/c, monoclinic space group P2 1/n, and monoclinic space group P21/n, respectively. Complexes 1 and 2 consist of a trapped-valence tetranuclear core of [Mn II2MnIII2(μ4-0)] 8+, and complexes 3 and 4 represent a new structural type, possessing a [MnII3MnIII3(μ4-O) 2]11+ core. The magnetic data indicate that complexes 3 and 4 have a ground-state spin value of S = 7/2 with significant magnetoanisotropy as gauged by the D values of -0.51 cm-1 and -0.46 cm-1, respectively, and frequency-dependent out-of-phase signals in alternating current magnetic susceptibility studies indicate their superparamagnetic behavior. In contrast, complexes 1 and 2 are low-spin molecules with an S = 1 ground state. Single-molecule magnetism behavior confirmed for 3 the presence of sweep-rate and temperature-dependent hysteresis loops in single-crystal M versus H studies at temperatures down to 40 mK.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry