Synthesis and characterization of oxo-bridged, trinuclear, six-coordinate mixed-carboxylato complexes of chromium (III)

Mixed-carboxylato β-diketonato complexes of chromium (III) (R=C₁₃H₂₇, C₁₅H₃₁ or C₁₇H₃₅ and L=CH₃OH) [Cr₃O(OOCR)₃(dike)₃L₃]⁺ have been synthesized by enforced substitution reactions of [Cr₃O(OOCCH₃)₇(H₂O)] first with straight chain fatty acids (myristic, palmitic or stearic acid) and then with β-diketones (Hβ-dike) like acetylacetone(Hacac) or benzoylacetone(Hbzac) in toluene under reflux. These are new type of oxo-bridged chromium(III) complexes in which one ligand is a fatty acid while the other one is a β-diketone. The complexes were characterized by elemental analyses, spectral (infrared, electronic, FAB mass and powder XRD) studies, molar conductance and magnetic susceptibility measurements. Bridging coordination modes for both carboxylate and β-diketonate anions were indicated by presence of ν_asym(Cr₃O) vibrations in the infrared spectra. Trinuclear nature of the complexes and their structural features have been discussed on the basis of physicochemical studies.