Structure and Magnetic Properties of a Dodecanuclear Twisted-ring Iron(III) Cluster

[Fe(OMe)2(dbm)]12 (I; Hdbm = dibenzoylmethane) was prepd. by the reaction of FeCl3 with Hdbm in presence of KOMe or CsOMe in anhyd. MeOH. I.6CHCl3 is monoclinic, space group P21/c, Z = 4, R = 0.0967, Rw = 0.3174. Each Fe(III) in I has a distorted octahedral environment with 6 O atoms from methoxide and dbm with Fe-O band lengths of 1.94-2.07 Å, forming a twisted ring which is not planar and has C1 point group symmetry. NMR data of I in presence of NaBPh4 or LiBPh4 indicate that I is quant. converted to hexairon(III) coronates, [MFe6(OMe)12(dbm)6]+. Magnetic susceptibility data indicate antiferromagnetic coupling in I between high-spin Fe(III) atoms.