Three-Dimensional Linkage by Electron Donor-Acceptor Interactions: Complexes of Organic Ammonium Halides with Triiodomethane

Article abstract of DOI:10.1021/jo00183a025

The preparation of a series of crystalline organylammonium halide complexes with triiodomethane is reported.The crystal structures of three complexes have been determined from single-crystal X-ray diffractometry data.The characteristic crystal data of the complexes are compared and their structures are discussed.The I(-)...I distances are about 0.75 Angstroem shorter than that anticipated for van der Waals contact, indicating that electron donor-acceptor bonds are present.The I(-)...I-C arrangement is nearly linear in all cases.Three-dimensional space networks as well as smaller units are formed by I(-) anions and triiodomethane molecules due to charge-transfer interactions.Raman data of a few of the charge-transfer complexes are quoted.Several bands are shifted from their positions in the pure components and some degenerate modes are split.Electrical conductivity measurements show some of the complexes are organic semiconductors in the solid state. (13)C NMR investigations in Me2SO-d6 verify the existence of a charge transfer from iodide ions to HCI3 molecules also in the dissolved state.The complex formation constant (K = 2.0 L/mol, in Me2SO-d6) has been determined from the I(-) concentration dependence of the chemical shift of the HCI3 carbon nucleus.