VIBRATIONAL-SPECTRA OF (CH3)3M-C=C-C=C-M(CH3)3, WITH M = C, SI, GE, OR SN

Infrared spectra from 200 to 4000 cm-1 and Raman spectra from 80 to 4000 cm-1 have been recorded for the molecules (CH3)3MCCCCM(CH3)3 with M = C, Si, Ge, or Sn. Solid samples and solutions in several solvents have been used. Assignments of the fundamentals were made on the assumption of D3d symmetry, which proved quite satisfactory. In all, 140 of the 188 spectroscopically-active fundamentals for the four molecules have been assigned. The in-phase CC stretch is 115-135 cm-1 higher than the out-of-phase one. This is in sharp contrast to cumulated double bonds, where the in-phase stretch is roughly half the out-of-phase one. A rationalization of this is given. © 1979.