Stepwise substitution of oxo-centered, trinuclear chromium(III) carboxylates with Schiff base

Oxo-centered, trinuclear, mixed-ligand complexes of chromium(III) have been synthesized by stepwise substitutions of acetate ions of [Cr3O(OOCMe)(4)(OOCR)(3)] center dot 3MeOH (1) and the isolated products of the type [Cr3O(OOCMe)(2) (SB)(OOCR)(3)]PF6 center dot 3MeOH (2), [Cr3O(OOCMe)(SB)(2)(OOCR)(3)]PF6 center dot 3MeOH (3) and [Cr3O(SB)(3)(OOCR)(3)]PF6 center dot 3MeOH (4) [where R = C13H27 and HSB = C6H4(OH)CHNC6H4Cl] have been characterized by a full battery of complementary physico-chemical methods including spectral (infrared, electronic, FAB mass and powder XRD) studies, elemental and thermogravimetric analyses, molar conductance and magnetic susceptibility measurements. The infrared spectra suggest the bridging nature of both carboxylate and Schiff base anions along with nu (asym)(Cr3O) vibrations in the complexes. The trinuclear nature of the complexes has been assessed from FAB mass data. Electronic spectra and magnetic moment values were consistent with chromium(III) ion present in an octahedral environment which was supported by their powder X-ray diffraction data. Cyclic voltammetric data of complex (4) indicate a reversible oxidation wave and an irreversible reduction wave in the range - 1.2-0.6 V. The decomposition pathway of all the complexes has been discussed on the basis of thermogravimetric analysis data. Conductance data indicate the monocationic nature of the complexes and their plausible structure has been established on the basis of above physico-chemical studies.