Binuclear Ten-Membered Ring Cyclometallated Complexes of Digold(I) and their Reactions with Iodine and Bromine

Abstract

The cyclometallated digold(I) complexes [Au2(μ-2-C6H4CH2PPh2)2] (10) and [Au2(μ-2-CH2C6H4PPh2)2] (11) have been synthesized by the reaction of Li[2-C6H4CH2PPh2] and Li[2-CH2C6H4PPh2], respectively, with [AuBr(PEt3)]. A single crystal X-ray structure analysis of 10 shows the linearly coordinated gold(I) atoms to be separated by 3.0035(9) Å in a puckered ten-membered ring. Both complexes add one mol equivalent of iodine to form initially gold(I)-gold(III) complexes [Au(μ-2-C6H4CH2PPh2)2AuI2] (14a) and [Au(μ-2-CH2C6H4PPh2)2AuI2] (17), which isomerize to the corresponding salts [Au(κ2-P,C-C6H4CH2PPh2)2][AuI2] (13a) and [Au(κ2-P,C-CH2C6H4PPh2)2][AuI2] (16). In 13a the gold(III) cation is planar coordinated by a pair of chelate P-C donor ligands, the phosphorus and carbon atoms being, separately, mutually cis, as shown by X-ray structural analysis. From the reaction of 10 with 2 mol equivalents of bromine, the neutral chelate complex [AuBr2(κ2-P,C-C6H4CH2PPh2)] (15) has been isolated and structurally characterized.