Crystal structures of ten phosphane chalcogenide complexes of gold(III) chloride and bromide.

The structures of ten phosphane chalcogenide complexes of gold(III) halides, with general formula R 1 3- n R 2 n P E Au X 3 ( R 1 = t -butyl; R 2 = i -propyl; n = 0 to 3; E = S or Se; X = Cl or Br) are presented. The eight possible chlorido derivatives are: 9a , n = 3, E = S; 10a , n = 2, E = S; 11a , n = 1, E = S; 12a , n = 0, E = S; 13a , n = 3, E = Se; 14a , n = 2, E = Se; 15a , n = 1, E = Se; and 16a , n = 0, E = Se, and the corresponding bromido derivatives are 9b - 16b in the same order. Structures were obtained for 9a , 10a (and a second polymorph 10aa ), 11a (and its deutero-chloro-form monosolvate 11aa ), 12a (as its di-chloro-methane monosolvate), 14a , 15a (as its deutero-chloro-form monosolvate 15aa , in which the solvent mol-ecule is disordered over two positions), 9b , 11b , 13b and 15b . The structures of 11a , 15a , 11b and 15b form an isotypic set, and those of compounds 10aa and 14a form an isotypic pair. All structures have Z ' = 1. The gold(III) centres show square-planar coordination geometry and the chalcogenide atoms show approximately tetra-hedral angles (except for the very wide angle in 12a , probably associated with the bulky t -butyl groups). The bond lengths at the gold atoms are lengthened with respect to the known gold(I) derivatives, and demonstrate a considerable trans influence of S and Se donor atoms on a trans Au-Cl bond. Each compound with an isopropyl group shows a short intra-molecular contact of the type C-H methine ⋯ X cis ; these may be regarded as intra-molecular 'weak' hydrogen bonds, and they determine the orientation of the Au X 3 groups. The mol-ecular packing is analysed in terms of various short contacts such as weak hydrogen bonds C-H⋯ X and contacts between the heavier atoms, such as X ⋯ X ( 9a , 10aa , 11aa , 15aa and 9b ), S⋯S ( 10aa , 11a and 12a ) and S⋯Cl ( 10a ). The packing of the polymorphs 10a and 10aa is thus quite different. The solvent mol-ecules take part in C-H⋯Cl hydrogen bonds; for 15aa , a disordered solvent region at z ≃ 0 is observed. Structure 13b involves unusual inversion-symmetric dimers with Se⋯Au and Se⋯Br contacts, further connected by Br⋯Br contacts.