ChemInform Abstract: Crystal Structure, Raman and Resonance Raman Spectroscopic Studies of the Dimethyl Diquaternary Salt of 2,2′‐Dicyano‐4,4′‐bipyridine and Its Radical Monocation

Abstract

Abstract The crystal structure of the dimethyl diquaternary salt of 2,2′-dicyano-4,4′-bipyridine is reported. Crystal data: C14H12Br2N4, Mr = 396.1, a = 7.1934(9), b = 10.192(1), c = 10.715(1) A, β = 103.89(1)°, V = 762.61 A3, monoclinic, space group P21/n, Z = 2, Dm = 1.70, Dc = 1.73 g cm−3, Mo Kα, λ = 0.71069 A, μ = 56.24 cm−1, F(000) = 388, T = 293 ± 1 K, R = 0.028, Rw = 0.029 for 1156 (I > 2.50σ(I)) reflections. The cation straddles a crystallographic centre of symmetry with the two pyridine rings being coplanar. The bromide ion is in a general position. Bond lengths and angles are normal. Raman spectra of the parent dication and resonance Raman spectra of the coloured radical monocation are also reported. The CN stretching frequency for the radical monocation is only weakly enhanced and is displaced only 12 cm−1 from the corresponding feature for the parent dication.