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

Abstract

The structures of ten phosphane chalcogenide complexes of gold(III) halides, with general formula R13–nR2nPEAuX3 (R1 = t-butyl; R2 = 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 deuterochloroform monosolvate 11aa), 12a (as its dichloromethane monosolvate), 14a, 15a (as its deuterochloroform monosolvate 15aa, in which the solvent molecule 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 tetrahedral 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 intramolecular contact of the type C—Hmethine...Xcis; these may be regarded as intramolecular ‘weak’ hydrogen bonds, and they determine the orientation of the AuX3 groups. The molecular 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 molecules 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.

Keywords

• crystal structure
• gold(iii) halides
• phosphane chalcogenides
• secondary interactions