Preparation and magnetic properties of low symmetry [Mn4O3] complexes with S=9/2

Controlled potential electrolysis (CPE) procedures have provided access to a family of distorted trigonal pyramidal [Mn4O3(O2CR)(4)(dbm)(3)] complexes (where R = C6H5 (1), C6H4-p-Me (2) and C6H4-p-7-MeO (3)) with an asymmetric [Mn-4(mu (3)-O-3)(eta (2),mu (3)-O2CR)](6+) core. This results in C-s symmetry, lower than previous [Mn4O3X(O2CMe)(4)(dbm)(3)] complexes with C-3v symmetry. The dc magnetic susceptibility data of the C-s symmetry clusters are similar to those of the C-3v symmetry complexes, and fits of the data show a ferromagnetic coupling between Mn(III)-Mn(III) and antiferromagnetic coupling between the three Mn(III)-Mn(IV) pairs, giving a resultant S = 9/2 ground state. The out-of-phase ac susceptibility indicates slow magnetization relaxation and that these molecules are single-molecule magnets at low temperatures. (C) 2001 Elsevier Science Ltd. All rights reserved.