Fourier transform microwave spectroscopy of isotopically substituted diacetylenes: rs-structure, quadrupole coupling, and anisotropic nuclear spin–spin interaction (original) (raw)

2006, Journal of Molecular Spectroscopy

Monodeuterated diacetylene (HCCCCD) and its 13 C-substituted species H 13 CCCCD, HC 13 CCCD, HCC 13 CCD, and HCCC 13 CD were investigated by Fourier transform microwave spectroscopy. The D nuclear quadrupole splittings were almost completely resolved. For H 13 CCCCD hyperfine splittings caused by the anisotropic nuclear spin-spin interaction between the H and 13 C nuclei were also observed. The analysis yielded rotational constants, centrifugal distortion constants, and the constants for the nuclear quadrupole coupling and anisotropic nuclear spin-spin interaction. The substitution structure of HCCCCD was calculated as follows: r s (C-H) = 1.056054(39) Å , r s (C"C) = 1.208631(4) Å , r s (C-C) = 1.374117(6) Å , r s (C"C) = 1.208116(4) Å , and r s (C-D) = 1.056231(17) Å , in the order of the arrangement of the bonds. A rough estimate of the equilibrium structure is also presented. The eQq constant for the deuterium nucleus is 0.2061(4) MHz. The anisotropic 13 C-H spin-spin interaction constant was experimentally determined for the first time as b = À29.2(15) kHz, which is defined as the coefficient of (3I 2z I 3z À I 2 AE I 3 ), where I 2 and I 3 denote the H and 13 C nuclear spins, respectively, and I 2z and I 3z their components along the molecular axis. The observed b constant is not accounted for by the direct magnetic dipole-dipole interaction only, suggesting a significant contribution from indirect anisotropic interaction.

Sign up for access to the world's latest research.

checkGet notified about relevant papers

checkSave papers to use in your research

checkJoin the discussion with peers

checkTrack your impact