A short C–H···N hydrogen bond with a very strong IR spectroscopic effect

Abstract

The crystal structure of 3-methylthio-4-propargylselenoquinoline contains a very short CC–H···N hydrogen bond with H···N and C···N distances of 2.17 and 3.225(4) Å, respectively. The bathochromic shift of the infrared acetylenic C–H stretching vibration ν_CH is 176 cm⁻¹. The geometry as well as the spectral effects come close to the shortest well-studied C–H···N hydrogen bond, which occurs in solid HCN (C···N = 3.18 Å, bathochromic shift 180 cm⁻¹). The hydrogen bond energy is calculated as −3.4 kcal mol⁻¹. A correlation of ν_CHbathochromic shift against C···N distance is established for CC–H···N hydrogen bonds.