Crystal structures of sixteen phosphane chalcogenide complexes of gold(I) chloride, bromide and iodide.

The structures of 16 phosphane chalcogenide complexes of gold(I) halides, with the general formula R 1 3- n R 2 n P E Au X ( R 1 = t -butyl; R 2 = isopropyl; n = 0 to 3; E = S or Se; X = Cl, Br or I), are presented. The eight possible chlorido derivatives are: 1a , n = 3, E = S; 2a , n = 2, E = S; 3a , n = 1, E = S; 4a , n = 0, E = S; 5a , n = 3, E = Se; 6a , n = 2, E = Se; 7a , n = 1, E = Se; and 8a , n = 0, E = Se, and the corresponding bromido derivatives are 1b - 8b in the same order. However, 2a and 2b were badly disordered and 8a was not obtained. The iodido derivatives are 2c , 6c and 7c (numbered as for the series a and b ). All structures are solvent-free and all have Z ' = 1 except for 6b and 6c ( Z ' = 2). All mol-ecules show the expected linear geometry at gold and approximately tetra-hedral angles P- E -Au. The presence of bulky ligands forces some short intra-molecular contacts, in particular H⋯Au and H⋯ E . The Au- E bond lengths have a slight but consistent tendency to be longer when trans to a softer X ligand, and vice versa . The five compounds 1a , 5a , 6a , 1b and 5b form an isotypic set, despite the different alkyl groups in 6a . Compounds 3a / 3b , 4b / 8b and 6b / 6c form isotypic pairs. The crystal packing can be analysed in terms of various types of secondary inter-actions, of which the most frequent are 'weak' hydrogen bonds from methine hydrogen atoms to the halogenido ligands. For the structure type 1a , H⋯ X and H⋯ E contacts combine to form a layer structure. For 3a / 3b , the packing is almost featureless, but can be described in terms of a double-layer structure involving borderline H⋯Cl/Br and H⋯S contacts. In 4a and 4b / 8b , which lack methine groups, C meth-yl -H⋯ X contacts combine to form layer structures. In 7a / 7b , short C-H⋯ X inter-actions form chains of mol-ecules that are further linked by association of short Au⋯Se contacts to form a layer structure. The packing of compound 6b/6c can conveniently be analysed for each independent mol-ecule separately, because they occupy different regions of the cell. Mol-ecule 1 forms chains in which the mol-ecules are linked by a C methine ⋯Au contact. The mol-ecules 2 associate via a short Se⋯Se contact and a short H⋯ X contact to form a layer structure. The packing of compound 2c can be described in terms of two short C methine -H⋯I contacts, which combine to form a corrugated ribbon structure. Compound 7c is the only compound in this paper to feature Au⋯Au contacts, which lead to twofold-symmetric dimers. Apart from this, the packing is almost featureless, consisting of layers with only translation symmetry except for two very borderline Au⋯H contacts.