MIXED-VALENT LINEAR-CHAINS OF GOLD ATOMS - X-RAY STRUCTURE OF [((2,4,6-C6F3H2)AU(CH2PPH2CH2)2AU)2AU(CH2PPH2CH2)2AU](CLO4)2

Reactions of asymmetrical gold(II) derivatives [RAu(CH2PPh2CH2)2AuX] (R = C6F5, 2,4,6-C6F3H2; CH3, X = halogen) with AgClO4 lead to the compounds [RAu(CH2PPh2CH2)2AuOClO3], which further react with NBu4[AuR2] (R = C6F5, C6F3H2) or [Au(CH2PPh2CH2)2Au] to give pentanuclear [{RAu(CH2PPh2CH2)2Au}2AuR21ClO4 or hexanuclear [{RAu(CH2PPh2CH2)2-Au}2Au(CH2PPh2CH2)2Au](ClO4)2 gold complexes in different oxidation states. The same results can be achieved if the reactions are carried out with [RAu(CH2PPh2CH2)2Au(tht)]ClO4 (tht = tetrahydrothiophene). The structure of [{(2,4,6-C6F3H2)Au(CH2PPh2CH2)2AU}2Au(CH2PPh2-CH2)2Au](ClO4)2 has been determined by a single-crystal X-ray diffraction study. It crystallizes in the monoclinic space group P2(1)/c with a = 12.150(1) angstrom, b = 15.498(2) angstrom, c = 24.693(2) angstrom, beta = 95.18(l)-degrees, Z = 2, R = 0.0404, and R(w) = 0.0417 for 5132 observed reflections. The centrosymmetric cationic complex exhibits a linear hexametallic skeleton and is composed of three pairs of gold atoms, each of them doubly bridged by two bis-ylide ligands. Two sigma-bonded C6F3H2 groups complete the coordination of the external gold centers. The three ''Au(CH2PPh2CH2)2AU'' moieties are held together through two unbridged Au-Au direct bonds (2.7370(7) angstrom), with the ligand-bridged Au-Au separations at 2.6540(7) and 2.8378(7) angstrom.