Group 11 metal(I) complexes with low co-ordination numbers: the crystal structures of [PPh3Me]2[CuBr3], [PPh3Me]2[CuBr2]Br, and [PPh3Me]2[AgI3]

Abstract

The crystal structures of [PPh₃Me]₂[CuBr₃], [PPh₃Me]₂[CuBr₂]Br, and [PPh₃Me]₂[AgI₃] have been determined by single-crystal X-ray diffraction methods at 295 K. The salt [PPh₃Me]₂[CuBr₃] contains a planar, almost perfectly trigonal tribromocuprate (I) ion [CuBr₃]^2–. The exact symmetry of the ion in the crystal is C_2v, with Cu–Br bond lengths of 2.353(3)(twice) and 2.358(6)Å and Br–Cu–Br angles of 118.9(1)(twice) and 122.2(2)°. The salt [PPh₃Me]₂[CuBr₂]Br contains [CuBr₂]^– ions and separate Br^– ions at distances greater than 6.8 Å from the nearest copper atom. The structure of the [CuBr₂]^– ion is almost linear, with Cu–Br bond lengths of 2.228(1) and 2.233(1)Å and a Br–Cu–Br angle of 175.29(4)°. The salt [PPh₃Me]₂[AgI₃] contains a planar triiodoargentate(I) ion [AgI₃]^– with approximate trigonal symmetry. The Ag-I bond lengths are 2.742(1), 2.746(1), and 2.755(1)Å and the I–Ag–I angles are 115.90(3), 119.38(4), and 124.67(3)°. This appears to be one of very few examples of a mononuclear, trigonally co-ordinated silver(I) complex. The possible relevance of this structure to the mechanism of conductivity in iodoargentate(I) solid-state electrolytes is discussed.