Gold complexes [Ph3PCH2CH=CHCH2PPh3]2+[AuCl4] 2 − and [Ph3PCH2CH2COOH]+[AuCl4]−: Synthesis and structure

Complexes [Ph3PCH2CH=CHCH2PPh3]2+[AuCl4]2− (I) and [Ph3PCH2CH2COOH]+[AuCl4]− (II) have been synthesized by the reaction of hydrotetrachloroauric acid with 2-butene-1,4-bis(triphenylphosphonium) dichloride (2: 1 mol/mol) and 2-carboxyethyltriphenylphosphonium chloride (1: 1 mol/mol). The phosphorus atoms in the cations of complexes I and II have a slightly distorted tetrahedral coordination (CPC, 106.5(7)°–112.5(8)°), and P-C bond lengths are 1.768(14)–1.819(17) A. The square coordination of the gold atom in the anions of complexes I and II is almost undistorted: ClAuCl angles are 88.53(6)°–91.3(3)°, Au-Cl bond lengths are 2.254(5)–2.289(6) A. The cations in crystals are bonded by H⋯Cl hydrogen bonds of 2.72–2.79 A I) and 2.77–2.85 A II). The cations of complex II form dimers due to strong H⋯O bonds (1.85 A) between carboxyl groups.