Bis(η-arene) complexes of the early transition metals derived from the 1,3,5-tri-t-butylbenzene ligand

Abstract

Co-condensation of yttrium, titanium, zirconium, hafnium, niobium, chromium, molybdenum or tungsten atoms with the bulky arene 1,3,5-tri-t-butylbenzene, affords the homoleptic sandwich compounds [M(η-tBu3C6H3)2], where M = Y, Ti, Zr, Hf, Nb, Cr, or W; in the case of chromium, the reaction also yields the triple-decker sandwich compound [Cr2(η-tBu3C6H3) 2(μ-η:η-tBu3C6H3)]. [Hf(η-tBu3C6H3)2] reacts irreversibly with carbon monoxide to give the stable 18-electron carbonyl adduct [Hf(η-tBu3C6H3)2(CO)], whereas [Zr(η-tBu3C6H3)2(CO)] is unstable in the absence of excess carbon monoxide. Oxidation of [Nb(η-tBu3C6H3)2] with silver tetrafluoroborate affords the stable 16-electron cation [{Nb(η-tBu3C6H3)2BF4}].