Structural characterization, magnetic studies, and catecholase-like activities of Mn12 clusters

Two polynuclear, mixed-valence, sandwich dodecanuclear manganese clusters [(Mn4Mn4Mn4II)-Mn-II-Mn-III(mu(4)-O)(2)(mu(3)-O2CH)(2)(thme)(4)(MeCO2)(10)(H2O)(4)]center dot 4H(2)O (1) and [(Mn4Mn4Mn4II)-Mn-II-Mn-III(mu(4)-O)(2)(mu(3)-O)(2)(thmp)(4)(MeCO2)(10)(H2O)(4)](1)center dot 10H(2)O (2) are reported by the reaction of 1,1,1-tris(hydroxymethyl)ethane (H(3)thme) or 1,1,1-tris(hydroxymethyl)propane (H(3)thmp) with manganese(II) salts in methanol under reflux conditions. 1 and 2 were characterized by single-crystal X-ray diffraction, PXRD, cyclic voltammetry (CV), and variable temperature magnetic studies. 1 and 2 crystallize in the monoclinic (P2(1)/n) and triclinic (P-1) systems, respectively, and each structure consists of a dodecanuclear mixed-valent Mn(4)(II)Mn(4)(III)Mn(4)(II)sandwich core. Magnetic data confirmed that both complexes show dominant antiferromagnetic interactions between metal centers. The fascinating features of the non-covalent supramolecular contacts have been explored. The interplay of O center dot center dot center dot H interactions (i.e. O-H center dot center dot center dot O and C-H center dot center dot center dot O contacts) gives rise to the consolidation of discrete units of 1 and 2 into supramolecular architecture. Catecholase activity data show that the present clusters catalyze the oxidation of 3,5-DTBC to 3,5-DTBQ with efficient K-cat values. [GRAPHICS] . 10.1002/1521-3773(20021115)41:22<4318::AID-ANIE4318>3.0.CO;2