Reactions of pyridyl donors with halogens and interhalogens: an X-ray diffraction and FT-Raman investigation

Three different N-donors L, namely N-ethyl-N'-3-pyridyl-imidazolidine-4,5-dione-2-thione (1), N,N'-bis(3-pyridylmethyl)-imidazolidine-4,5-dione-2-thione (2), and tetra-2-pyridyl-pyrazine (3), bearing one, two and four pyridyl substituents, respectively, have been reacted with halogens X-2 (X = Br, I) or interhalogens XY (X = I; Y = Cl, Br). CT sigma-adducts L - nXY, bearing linear N --- XY moieties (L = 3; X = I; Y = Br, I; n = 2), and salts containing the protonated cationic donors HnLn+ (L = 1 - 3; n = 1, 2, 4), counterbalanced by Cl-, Br-, I-3(-), Br-3(-), I-5(-), Br-5(-), I2Br-, I3Br4-, or ICI2- anions, have been isolated. Among the reactions products, (H1(+))Cl-, (H1(+))Br-, (H2(+))I-3(-), (H(2)3(2+))(ICl2-)(2), and 3 - 2IBr have been characterised by single-crystal X-ray diffraction. The nature of the products has been elucidated based on elemental analysis and FT-Raman spectroscopy supported by MP2 and DFT calculations. (c) 2004 Elsevier B.V. All rights reserved.