CALIXARENE COMPLEXES OF THE MOLYBDENUM-MOLYBDENUM QUADRUPLE BOND

We report here the first examples of metal-metal quadruple bonds supported by calixarene ligands in the complexes [Mo-2(oAc>(2)(H-2-calix[4]arene)] (1) and [Mo-2(OAc)(2)(H-2-p-tert-butylcalix[4]arene (2). Complexes 1 and 2 were prepared by first deprotonating calix[4]arene and p-tert-buty]-calix[4]arene, respectively, with two equivalents of KH, followed by the addition of [Mo-2(OAc)(2)(NCMe)(6)][BF4](2). X-ray crystallographic analysis revealed the solid state structure of 2(THF). C6H6. A molybdenum-molybdenum quadruple bond (2.1263(6) Angstrom) is spanned by two bridging acetate ligands and a tetradentate, doubly-deprotonated calixarene macrocycle. Each Mo-Mo unit is weakly coordinated by an axial THF solvent molecule which is included in the calixarene basket of the neighboring complex.