A low-temperature neutron diffraction study of Mn-12-acetate

In the low-temperature region, where the dodecanuclear mixed-valence mangan ese carboxylate hexadecaacetatotetra-aquadodecaoxododecamanganese bis(aceti c acid) tetrahydrate, [Mn12O12(C2D3O2)(16)(H2O)(4)]. 2C(2)HD(3)O(2). 4H(2), displays unusual magnetic properties, its structure is similar to that pre viously determined at room temperature [Lis (1980). Acta Cryst. B36, 2042-2 046], differing only by a small change in the configuration of one of the c oordinated acetate groups, related to the formation of additional hydrogen bonds, and by the orientation of the methyl groups. Since most of the magne tization density of this system resides on the Mn atoms, the consequences o f these rearrangements for the magnetic properties of the compound are smal l.