Calix[4]arene as a polyoxo matrix for functionalizable and reducible niobium(V) and tantalum(V) chlorides and oxochlorides
Abstract
Reaction of MCl5(M = Nb or Ta) with p-butylcalix[4]arene, L-(OH)4, led, depending on the reaction conditions, either to mononuclear complexes [(AcO)–L–(O)3MCl2], or, in the case of niobium only, to the tetranuclear complex [{µ-L-(O)4}2Nb4O2Cl8], characterized by X-ray analysis.