Synthesis and structural characterization of [NEt4][Fe3(μ3-O)(μ3-AuPPh3)(μ-CO)3(CO)6], the new [Au6(μ3-S)2(PPh3)6][Fe3(μ3-S)(μ-AuPPh3)(CO)9]2 and [Au6(μ3-S)2(PPh3)6][Fe5(μ3-S)2(CO)14] ionic solids containing assemblages of cluster-cations and cluster-anions

The new [Fe-3(mu(3)-O)(mu(3)-AuPPh3)(mu-CO)(3)(CO)(6)](-) and [Fe-3(mu(3)-S)(mu-AuPPh3)(CO)(9)](-) monoanionic congeners have been obtained by reacting the [Fe-3(mu(3)-E)(CO)(9)](2-) (E = O, S) dianions with one equivalent of Au(PPh3)Cl. The gold adduct of the oxygen derivative has been crystallized as tetraethylammonium and trimethylbenzylammonium salt either from THF and n-hexane or acetone and isopropyl alcohol, and structurally characterized in its tetraethylammonium salt (monoclinic, C2/c (No. 15), a = 15.859(2). b = 12.859(2), c = 40.217(8) Angstrom, beta = 96.41(1)degrees Z = 8). The [Fe-3(mu(3)-S)(mu-AuPPh3)(CO)(9)](-) gold adduct, in contrast, partially reverts to the parent dianion upon crystallization under the above experimental conditions, and could be precipitated only as the [Au-6(mu(3)-S)(2)(PPh3)(6)][Fe-3(mu(3)-S)(mu-AuPPh3)(CO)(9)](2) salt (triclinic, P (1) over bar (No. 2), a = 18.998(8), b = 19.933(8), c = 22.94(1) Angstrom, alpha = 99.91(4), beta = 98.91(4), gamma = 107.42(3)degrees Z = 2), by addition of an equivalent of the [Au-3(mu(3)-S)(PPh3)(3)](+) sulfonium cation to the reaction mixture. The [Fe-5(mu(3)-S)(2)(CO)(14)](2-) dianion does not form a gold adduct even in the presence of the sulfonium cation and only the corresponding [Au-6(mu(3)-S)(2)(PPh3)(6)][Fe-5(mu(3)-S)(2)(CO)(14)] salt could be obtained. The [Fe-3(mu(3)-O)(mu(3)-AuPPh3)(mu-CO)(3)(CO)(6)](-) and [Fe-3(mu(3)-S)(mu-AuPPh3)(CO)(9)](-) gold adducts are not isostructural and the possible factors leading to their structural diversities are discussed. The [Au-6(mu(3)-S)(2)(PPh3)(6)][Fe-3(mu(3)-S)(mu-AuPPh3)(CO)(9)](2) and [Au-6(mu(3)-S)(2)(PPh3)(6)][Fe-5(mu(3)-S)(2)(CO)(14)] salts represent further examples of ionic solids assembled from cluster-cations and cluster-anions. (C) 1999 Elsevier Science S.A. All rights reserved.