Preparation and characterization of novel oxo-centered basic p-chlorobenzoic bridging trinuclear complexes

Three new oxo-centered trinuclear complexes, one of them a mixed- -valence complex (Mn3O(C7H4O2Cl)6(Py)3)Py (1) and the others, mixed-metal complexes of (Fe2MnO(C7H4O2Cl)6(Py)3)NO3 (2) and (Fe2CoO(C7H4O2Cl)6(Py)3) (3) were synthesized by the direct reaction between metal nitrates and p-chlo- robenzoic acid. These complexes were characterized by elemental analyses (CHN), atomic absorption spectroscopy and spectral (IR, electronic) studies. These are new type of oxo-bridged mixed-metal complexes in which the car- boxylate ligand is p-chlorobenzoic acid. The UV spectra of the complexes exhibited a strong band in the region 42,500 cm -1 which is related to the (π → → π*) transitions of the pyridine ligand. The IR spectra of these compounds showed two strong stretching vibrations bands, indicating a bridging coordi- nation mode of the carboxylic group of the ligand in the complexes.