Comments on: The nature of the C≡S Triple bond: Part 2

By: Contriving aromaticity from S≡C Triple bonds « Henry Rzepa

Contriving aromaticity from S≡C Triple bonds « Henry Rzepa — Fri, 01 Jan 2010 12:03:01 +0000

[...] degree of SC triple character (HCS+) has around 3.8 in the same region, and perhaps a better model (TfOSCH, for which the carbon, like here, has a carbene lone pair) has 2.6. Each carbon also has the [...]

By: The nature of the C≡S triple bond: part 3. « Henry Rzepa

The nature of the C≡S triple bond: part 3. « Henry Rzepa — Sun, 06 Dec 2009 10:57:29 +0000

[...] Henry Rzepa Chemistry with a twist « The nature of the C≡S Triple bond: Part 2 [...]

By: Henry Rzepa

Henry Rzepa — Sat, 05 Dec 2009 17:40:13 +0000

As a follow-up to the post, the HC≡S-OTf system was noted to have a (gas phase) dipole moment of 5.6D, the result of shifting charge from the carbon lone pair to the S-OTf region. This dipole is the value at which solvation starts to have a discernible influence. Thus re-optimizing the geometry (B3LYP/cc-pVTZ/SCRF, DOI: 10042/to-3155) for a relatively non-polar solvent (benzene) is sufficient to induce the following changes: the dipole moment increases to 9.3D, the CS bond length decreases to 1.482Å, and the ν_{CS stretch} increases to 1424 cm^-1. For a more polar solvent (dichloromethane, DOI: 10042/to-3157), the values continue this trend towards HCS⁺: 13.3D, 1.476Å and 1446 cm^-1.