Attempted oxidative addition of halogens to (isocyanide)gold(I) complexes

Oxidative addition of bromine to an (isocyanide)gold(I) bromide proceeds smoothly to give the corresponding (isocyanide)gold(III) tribromide as demonstrated by the preparation and structural characterization of ((BuNC)-Bu-t)AuBr3. By contrast, no oxidative addition of iodine is observed with (isocyanide)gold(l) iodides. Ligand redistribution to give ionic compounds and intercalation Of 12 molecules occurs instead as shown for [((BuNC)-Bu-t)(2)Au](+)[AuI2](-) (12). In crystals of this product, linear chains of almost equidistant gold atoms of alternating cations and anions feature interionic aurophilic bonding [Au- - -Au 3.2674(5) and 3.3056(5) angstrom]. The iodine molecules form polyhalide bridges between the columns of complex ions. From the reaction mixture of ((c)HexNC)AuI and an excess of iodine a crystalline pentaiodide, [((c)HexNC)(2)Au](+)[I-5](-), has been isolated in which the cations are imbedded between corrugated sheets of the polyhalide anions.