Synthesis, spectroscopic studies and reactivity of monochlorotetrakis (2-/4- isopropylphenoxo) niobium (v) complexes

Complexes of composition [NbCl(OC6H4CH(CH3)2-2)4] (1) and [NbCl(OC6H4CH(CH3)2-4)4] (2) have been synthesized in quantitative yields by the reaction of niobium pentachloride with four equivalents of 2- and 4-isopropylphenols in carbon tetrachloride and characterized by elemental analyses, molar conductance, molecular weight determination, IR, 1H and 13C NMR and mass spectral studies. From these studies, a dimeric structure bridging through isopropylphenoxo group for the complexes has been inferred. The X-ray diffraction pattern of complexes has suggested amorphous nature of 1 and that of 2 as polycrystalline. The reactions of 1 and 2 with sodium alkoxides, NaOR (OR = OMe, OEt, OBut) yielded mixed alkoxo-phenoxo complexes of composition [Nb(OR)(OC6H4CH(CH3)2-2)4] and [Nb(OR)(OC6H4CH(CH3)2-4)4] authenticated by physicochemical, IR and 1H NMR spectral studies.