A Study of the Variable-Temperature Magnetic Susceptibility of Two Ti(III) Oxalate Complexes.

摘要

Variable-temperature magnetic susceptibility data have been obtained for polycrystalline samples of two Ti(III) oxalate complexes, Ti2(C2O4)3 (H2O)6.4H2O and Ti2(C2O4)3(H2O)5. The bridging oxalate dianion in the former complex (a seven-coordinate dimer with D(5h) symmetry) provides an effective path for magnetic exchange between the two Ti(III) ions as evidenced by a rather large intramolecular exchange parameter J = -60/cm. The partially dehydrated complex, by contrast, exhibits weak intradimer magnetic exchange interactions. Indeed, the variable-temperature magnetic susceptibility data for Ti2(C2O4)3(H2O)5 were fit to a distorted-octahedral, single-ion, spin-orbit coupling magnetic model with delta (ground term splitting) = 300/cm and K (orbital reduction factor) = 0.7 with gamma' = 155/cm. Room-temperature optical spectra of Ti2(C2O4)3(H2O)6.4H2O and Ti2(C2O4)3(H2O)5 were recorded and the resulting band assignments are consistent with D(5h) and distorted octahedral ligand-field symmetries, respectively. (Author)