Crystal structures of seven mixed-valence gold compounds of the form [( P)Au][Au ] ( = -butyl or isopropyl, = S or Se, and = Cl or Br).

During our studies of the oxidation of gold(I) complexes of tri-alkyl-phosphane chalcogenides, general formula PAu, ( = -butyl or isopropyl, = S or Se, = Cl or Br) with PhICl or elemental bromine, we have isolated a set of seven mixed-valence by-products, the bis-(tri-alkyl-phosphane chalcogenido)gold(I) tetra-halogenidoaurates(III) [( P)Au][Au ]. These corres-pond to the addition of one halogen atom per gold atom of the Au precursor. Com-pound , bis-(triiso-propyl-phosphane sulfide)-gold(I) tetra-chlorido-aur-ate(III), [Au(CHPS)][AuCl] or [( PrPS)Au][AuCl], crystallizes in space group 2/ with = 4; the gold(I) atoms of the two cations lie on twofold rotation axes, and the gold(III) atoms of the two anions lie on inversion centres. Compound , bis-(-butyl-diiso-propyl-phosphane sulfide)-gold(I) tetra-chlorido-aurate(III), [Au(CHPS)][AuCl] or [( Bu PrPS)Au][AuCl], crystallizes in space group 1 with = 4; the asymmetric unit contains two cations and two anions with no imposed symmetry. A least-squares fit of the two cations gave an r.m.s. deviation of 0.19 Å. Compound , bis-(tri--butyl-phosphane sulfide)-gold(I) tetra-chlorido-aurate(III), [Au(CHPS)][AuCl] or [( BuPS)Au][AuCl], crystallizes in space group 1 with = 1; both gold atoms lie on inversion centres. Compound , bis-(-butyl-diiso-propyl-phosphane sulfide)-gold(I) tetra-bromi-doaurate(III), [Au(CHPS)][AuBr] or [( Bu PrPS)Au][AuBr], crystallizes in space group 2/ with = 4; the cation lies on a general position, whereas the gold(III) atoms of the two anions lie on inversion centres. Compound , bis-(-butyl-diiso-propyl-phosphane selenide)gold(I) tetra-bromido-aurate(III), [Au(CHPSe)][AuBr] or [( Bu PrPSe)Au][AuBr], is isotypic with . Compound , bis-(tri--butyl-phosphane sulfide)-gold(I) tetra-bromido-aurate(III), [Au(CHPS)][AuBr] or [( BuPS)Au][AuBr], is isotypic with compound . Compound , bis-(tri--butyl-phosphane sulfide)-gold(I) tetra-bromido-aurate(III), [Au(CHPS)][AuBr] or [( BuPS)Au][AuBr], crystallizes in space group 1 with = 1; both gold atoms lie on inversion centres. Compound , bis-(tri--butyl-phosphane selenide)gold(I) tetra-bromido-aurate(III), [Au(CHPSe)][AuBr] or [( BuPSe)Au][AuBr], is isotypic with . All Au atoms are linearly coordinated and all Au atoms exhibit a square-planar coordination environment. The ligands at the Au atoms are anti-periplanar to each other across the S⋯S vectors. There are several short intra-molecular H⋯Au and H⋯ contacts. Average bond lengths (Å) are: P-S = 2.0322, P-Se = 2.1933, S-Au = 2.2915, and Se-Au = 2.4037. The complex three-dimensional packing of involves two short C-H⋯Cl contacts (and some slightly longer contacts). For , four C-H⋯Cl inter-actions combine to produce zigzag chains of residues parallel to the axis. Additionally, an S⋯Cl contact is observed that might qualify as a 'chalcogen bond'. The packing of is three-dimensional, but can be broken down into two layer structures, each involving an S⋯Cl and an H⋯Cl contact. For the bromido derivatives / and /, loose associations of the anions form part of the packing patterns. For all four compounds, these combine with an ⋯Br contact to form layers parallel to the plane.