FAR-INFRARED ASSIGNMENTS FOR BRIDGING COBALT-HALOGEN STRETCHING VIBRATIONS IN SEVERAL COORDINATION COMPOUNDS

Some coordination compounds of cobalt(II) of the type COL2X2 (L = py, 4-Cl(py), or 4-Br(py); X = Cl or Br) are known to exist in polymeric and monomeric forms. By following the appearance and disappearance of bands in the low-frequency spectra of both forms and by studying the effects of high pressure on these bands, assignments of bridging CoX stretching vibrations (vbCoX) have been made for the first time. The vbCoCl vibrations occur in the 155-186-cm-1 region. The rbCoBr vibrations occur in the 118-143-cm-1 region. The terminal CoX stretching vibrations (vtCoCl) occur in the 306-347-cm-1 region; the vtCoBr occur at 265 cm-1. © 1969, American Chemical Society. All rights reserved.