Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXII Synthesis, Spectroscopy and Structural Systematics of Some 1 : 2 Binuclear Complexes of Silver(I) Halides with Triphenylstibine, [(Ph3Sb)2Ag(μ-X)2Ag(SbPh3)2], X = Cl, Br, I

Abstract

Syntheses and room-temperature single-crystal X-ray structural characterization of binuclear 1 : 2 adducts formed between silver(I) halides, AgX (X = Cl, Br, I), and triphenylstibine, SbPh₃, are described. The three complexes are isomorphous, being triclinic, P^-1, a ≈ 18·5, b ≈ 14·6, c ≈ 14·5 Å, α ≈ 62·5, β ≈ 74, γ ≈ 77°, Z = 2 centrosymmetric dimers. Conventional R on F were 0·043, 0·038 and 0·046 for 4984, 8479 and 4166 independent, ‘observed’ (I > 3σ(I)) reflections respectively. In [(Ph₃b)₂Ag(µ-X)₂Ag(SbPh₃)₂], Ag–Sb range between 2·702(1) and 2·744(2) Å, lengthening slightly from chloride to iodide; Ag–X are 2·567(5)–2·628(4) (Cl), 2·684(1)–2·737(1) (Br) and 2·826(3)–2·869(3) Å (I). The far-infrared spectra of [(Ph₃Sb)₂Ag(µ-X)₂Ag(SbPh₃)₂] show v(AgX) bands at 178, 158 (X = Cl), 121 (X = Br) and 110 cm^-1 (X = I). The splittings and band widths reflect a decrease in the degree of distortion of the Ag(µ-X)₂Ag units from a symmetrically bridged structure from X = Cl to I.