Spectroscopic investigation on the trichloro-, tetrahalo- and mixed-tetrahalocuprates of the piperidinium and morpholinium cations.

Some halo- and mixed-halo-cuprates of the type CuCl3 \u2022 L, CuCl4 \u2022 L2, CuCl3Br \u2022 L2, CuCl2Br2 \u2022 L2 and CuBr4 \u2022 L2, were prepared and characterized by means of far-i.r., i.r. and n.i.r. spectroscopy, magnetic moments and conductivity measurements. A band at 19000 cm 121, which appears only in the CuCl3 \u2022 L complexes, is characteristic of Cu2Cl2- 6 dimer or polymer species. For these complexes and for CuCl4(Morph)2 and CuCl3Br(Morph)2 (Morph = morpholinium cation) an approaching square-planar geometry, while for all the other complexes a distorted-tetrahedral geometry, may be suggested from their spectroscopic properties, compared to those of other tri- and tetra-halo-cuprates of known structure. An intermediate structure between these geometries may be proposed for the CuCl3 \u2022 Pipd complex. The planar geometry is probably stabilized by extensive NH \u2026 Cl hydrogen bonding interactions greater with the morpholinium cation than with the piperidinium cation. No thermochromic behaviour in the solid state in the 290\u2013370\ub0 K temperature range is observed. The room-temperature magnetic moments agree with the proposed configurations