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

Abstract

Two new Mn(III) complexes with unprecedented topologies containing the tert-butylphosphonate ligand (t-BuPO3(2-)), [Mn9O6(t-BuPO3)2(O2CMe)11 (MeCOOH)(H2O)].8H2O(1), and [NBu(n)4][Mn13O6(t-BuPO3)10(OH)2(N3)6(MeCOOH)2(H2O)2].6H2O(2) have been prepared by treatment of Mn(O2CMe)2 and NBu(n)4MnO4 with tert-butylphosphonic acid in the presence of different bases. The core of 1 consists of two [Mn3O] units connected to a near linear [Mn3] unit by four mu3-O, while the core of 2 possesses a Mn centred disklike [Mn7O6] unit linked to six additional manganese atoms via six mu4-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'M T and out-of-phase signal chi"M, of the two complexes exhibit frequency-dependence below approximately 3 K.