Crystal structures of fourteen halochalcogenylphosphonium tetrahalogenidoaurates(III)

The structures of fourteen halochalcogenyl-phospho-nium tetra-halogen-ido-aurates(III), phosphane chalcogenide derivatives with general formula [R¹_3-nR²_nPEX][AuX₄] (R¹ = t-butyl; R² = isopropyl; n = 0 to 3; E = S or Se; X = Cl or Br) are presented. The eight possible chlorido derivatives are: 17a, n = 3, E = S; 18a, n = 2, E = S; 19a, n = 1, E = S; 20a, n = 0, E = S; 21a, n = 3, E = Se; 22a, n = 2, E = Se; 23a, n = 1, E = Se; and 24a, n = 0, E = Se, and the corresponding bromido derivatives are 17b-24b in the same order. Structures were obtained for all compounds except for the tri-t-butyl derivatives 24a and 24b. Isotypy is observed for 18a/18b/22a/22b, 19a/23a, 17b/21b and 19b/23b. In eleven of the compounds, X⋯X contacts (mostly very short) are observed between the cation and anion, whereby the E-X⋯X groups are approximately linear and the X⋯X-Au angles approximately 90°. The exceptions are 17a, 19a and 23a, which instead display short E⋯X contacts. Bond lengths in the cations correspond to single bonds P-E and E-X. For each group with constant E and X, the P-E-X bond-angle values increase monotonically with the steric bulk of the alkyl groups. The packing is analysed in terms of E⋯X, X⋯X (some between anions alone), H⋯X and H⋯Au contacts. Even for isotypic compounds, some significant differences can be discerned.