Synthesis and characterization of nona- and trideca-nuclear manganese phosphonate clusters

摘要

Two new Mn(III) complexes with unprecedented topologies containing the tert-butylphosphonate ligand (t-BuPO32-), [Mn9O6(t-BuPO3)(2)(O2CMe)(11)(MeCOOH)(H2O)] center dot 8H(2)O (1), and [NBu4n][Mn13O6(t-BuPO3)(10)(OH)(2)(N-3)(6)(MeCOOH)(2)(H2O)(2)] center dot 6H(2)O (2) have been prepared by treatment of Mn(O2CMe)(2) and (NBu4MnO4)-Mn-n with tert-butylphosphonic acid in the presence of different bases. The core of 1 consists of two [Mn3O] units connected to a near linear [Mn-3] unit by four mu(3)-O, while the core of 2 possesses a Mn centred disklike [Mn7O6] unit linked to six additional manganese atoms via six mu(4)-O. Compounds 1 and 2 are both homovalent manganese(III) cage clusters, of which the six-coordinated Mn centers are all Jahn-Teller distorted. Magnetic susceptibility measurements reveal that compounds 1 and 2 display overall ferromagnetic and antiferromagnetic interactions, respectively, between the adjacent Mn-III ions. Both the in-phase signal chi'T-M and out-of-phase signal chi ''(M) of the two complexes exhibit frequency-dependence below approximately 3 K.