Synthesis and Characterization of para‐Nitrophenoxides of Zirconium(IV)

Abstract Compounds of the composition ZrCl3(OC6H4NO2‐p) and ZrCl2(OC6H4NO2‐p)2 have been synthesized from the reaction of ZrCl4 with equimolar and bimolar amounts of the trimethylsilyl derivative of p‐nitrophenol in benzene under reflux. Attempts to isolate the tetrakis derivative, Zr(OC6H4NO2‐p)4, even by heating the components in high‐boiling solvents were unsuccessful. Based upon analytical data, conductance, cryoscopic, IR and 1H NMR studies, dimeric structures with bridging through phenoxo groups have been proposed for these compounds. The thermal decomposition of these complexes is a combination of both exothermic and endothermic processes, as is inferred from TG/DT studies. Reactions of these compounds with nitrogen bases viz., pyridine, 1,10‐phenanthroline and 2,2′‐bipyridyl results in breakdown of the bridged structure and formation of simple addition compounds, which have been assigned octahedral structures.