Journal of the American Chemical Society, Vol.118, No.20, 4839-4845, 1996
Aurophilicity at Sulfur Centers - Synthesis and Reactivity of the Complex (S(Au(2)Dppf)) - Formation of Polynuclear Sulfur-Centered Complexes - Crystal-Structures of (S(Au(2)Dppf))Center-Dot-2Chcl(3), ((Mu-Au(2)Dppf)(S(Au(2)Dppf))(2))(Otf)(2)Center-Dot-8Chcl(3), and (S(Aupph(2)Me)(2)(Au(2)Dppf))(ClO4)(2)Center-Dot-3Ch(2)Cl(2)
Treatment of [Au2Cl2(mu-dppf)] (dppf = 1,1’-bis(diphenylphosphino)ferrocene with Li2S (molar ratio 1:1) in ethanol gives a yellow solid [S(Au(2)dppf)] (1). The sulfur atom in complex 1 can coordinate several neutral or cationic gold(I) fragments giving the trinuclear neutral [S{Au(C6F5)}(Au(2)dppf)] (2) or cationic derivatives [S(AuL)-(Au(2)dppf)]ClO4 [L = CH(2)PPh(3) (3), PPh(3) (4), PPh(2)Me (5)]. A pentanuclear complex [Au{S(Au(2)dppf)(2)}]ClO4 (6) is obtained by reaction of 2 equiv of complex 1 with 1 equiv of [Au(tht)(2)]ClO4, in which the central gold atom is bonded to two sulfur atoms. Treatment of compound 1 with [Au-2(OTf)(2)(mu-dppf)] (OTf = trifluoromethylsulfonate) in a molar ratio 2:1 affords the hexanuclear complex [(mu-Au(2)dppf){S(Au(2)dppf)}(2)](OTf)(2) (7), in which two SAu3 units are joined through the dppf ligand. The reaction of 1 with 2 equiv of [Au(OClO3)PR(3)] leads to the quadruply bridging derivatives [S(AuPR(3))(2)(Au(2)dppf)](ClO4)(2) [PR(3) = PPh(3) (8), PPh(2)Me (9)]. Crystal structure determinations were performed for complexes, 1, 7, and 9. [S(Au(2)dppf)] (1) crystallizes in the monoclinic space group P-2/n, with a = 12.571(4) Angstrom, b = 10.579(4) Angstrom, c = 15.212(4) Angstrom, beta = 107.84(3)degrees, Z = 2, T = -130 degrees C. [(mu-Au(2)dppf){S(Au(2)dppf)}(2)](OTf)(2) (7) is triclinic, P (1) over bar, with a = 15.177(3), b = 18.408(4), c = 27.894(8) Angstrom, alpha = 88.83(2), beta = 84.46(2), gamma = 67.78(2), Z = 2, T = -100 degrees C. [S(AuPPh(2)Me)(2)(Au(2)dppf)](ClO4)(2) (9) is triclinic, P (1) over bar, with a = 13.727(2) Angstrom, b = 15.952(3) Angstrom, c = 17.763(2) Angstrom, alpha = 71.738(12)degrees, beta = 73.264(14)degrees, gamma = 75.96(2)degrees, Z = 2, T = -100 degrees C. All three complexes display short gold(I)-gold(I) interactions.