Syntheses and solid-state structures of molecular and extended silver(I) complexes, of 4-isocyano-3,5-diisopropylbenzonitrile

The molecular complexes [Ag(4-CN-3,5-i-Pr₂-C₆H₂CN)₂]X, 1 (a, X= BF₄; b, X= SO₃CF₃), have been prepared by reaction of the respective silver(I) salts with 2 equivalents of the isocyanide in benzene solution. Reaction of 1b with an equivalent amount of AgSO₃CF₃ in benzene solution gave the extended molecular solid {[Ag(4-CN-3,5-i-Pr₂-C₆H₂CN)₂]SO₃CF₃}(n), 2. The solid state structures of 1a and 2 have been determined by single-crystal X-ray crystallography. Compound 1a crystallizes in the triclinic space group P1̄ with a = 10.506(2) Å, b = 12.838(2) Å, c = 12.974(2) Å, α = 100.65(2)°, β = 101.52(2)°, γ = 105.37(2)°, V= 1600.1(7) ų, and Z = 2 with R = 0.056 and wR = 0.087. Compound 2 crystallizes in the triclinic space group P1̄ with a = 9.6868(8) Å, b = 10.551(1) Å, c = 11.559(1) A9, α = 76.350(9)°, β = 82.037(9)°, γ = 71.481(9)°, V = 1086.0(4) ų, and Z = 1 with R = 0.027 and wR = 0.036. Compound 1a may be described as a dicoordinate silver(I) complex with a significantly bent linear coordination geometry (C-Ag-C 156.1(2)°). The bending of the diisocyanide metal group is caused by the interaction with the BF₄ anion (shortest Ag-F distance 2.534(8)Å). The nitrile groups in 1b are not engaged in any directional intermolecular interaction. The solid-state structure of 2 consists of linear chains of [Ag(4-CN-3,5-i-Pr₂-C₆H₂CN)₂]SO₃CF₃ units, whereby each silver ion is coordinated to one isocyano group and one nitrile group of consecutive cyanoisocyanoarene ligands. These linear chains are arranged in antiparallel fashion to form infinite sheets. Within the sheets, the silver ions of pairs of chains are pulled near each other by electrostatic interactions with the SO₃CF₃ anions. These double chains are held together primarily by π interactions of the cyanoisocyanoarene groups. (C) 2000 Academic Press.