REINVESTIGATION OF THE VIBRATIONAL-SPECTRA OF MERCURY (II) HALIDE-COMPLEXES OF TRIPHENYLPHOSPHINE AND TRICYCLOHEXYLPHOSPHINE

The i.r. (350-130 cm-1) and Raman (350 cm- and below) spectra of the 1:1 and 2:1 complexes of mercury (II) halides (chloride, bromide, iodide) with triphenylphosphine and tricyclohexylphosphine have been examined. Spectra for the Ph3PHgX2 and Cy3PHgX2 complexes are consistent with a centrosymmetric dimeric structure of C2h skeletal symmetry. Spectra for the (Ph3P)2HgX2 and (Cy3P)2HgX2 complexes are in accord with a pseudotetrahedral structure of C2v symmetry. The Hg-X and Hg-P stretching frequencies for all the complexes have been assigned. The Hg-P stretching frequencies for the 1:1 complexes are higher than those for the 2:1 complexes. In each series of complexes, the Hg-P stretching frequencies decrease in the order Cl > Br > I. For the given mercury (II) halide, the Hg-P stretching frequency is higher for the complex containing less bulky phosphine. © 1979.