The molecular structure of 1,4-bis(trimethylsilyl)-1,3-butadiyne has been studied by the gas electron diffraction method and by ab initio calculations at the RHF and MP2 levels. A scaled quantum-chemical force field was used to interpret the vibrational spectra. The root-mean-square vibrational amplitudes and harmonic shrinkage corrections were calculated taking into account non-linear relations between Cartesian and internal vibrational co-ordinates at the level of first-order perturbation theory (h1) and with the use of the traditional scheme (h0). The total energies of the D3d and D3h conformers differ by about 1 cal mol-1 (0.4 cm-1) which implies virtually free internal rotation. It has been shown that the flexibility of the linear fragment in (CH3)3Si-C≡C-C≡C-Si (CH3)3 has increased considerably compared to that in (CH3)3Si-C≡C-Si(CH3)3.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Organic Chemistry
- Physical and Theoretical Chemistry
- Atomic and Molecular Physics, and Optics