A butterfly motion of formic acid and cyclobutanone in the 1 : 1 hydrogen bonded molecular cluster. Issue 1 (30th November 2016)

• Record Type: Journal Article
• Authors: Evangelisti, Luca; Spada, Lorenzo; Li, Weixing; Blanco, Susana; López, Juan Carlos; Lesarri, Alberto; Grabow, Jens-Uwe; Caminati, Walther
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 1(2017)
• Page Start: 204
• Page End: 209
• Publication Date: 2016-11-30
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp06941j
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Large tunnelling splittings reveal the relative motions and the inversion pathway in the formic acid–cyclobutanone cluster. Abstract : Upon supersonic expansion, formic acid and cyclobutanone (CBU) form a molecular cluster in which the two constituent molecules, linked by OH⋯O and CH⋯O hydrogen bonds, undergo a rapid interconversion between two equivalent forms. The tunneling motion takes place through the rupture and reformation of the C–H⋯O hydrogen bond between the carbonyl oxygen of HCOOH and one of the two hydrogen atoms of the methylenic group adjacent to the cyclobutanone keto group. From the microwave spectra, tunneling energy splittings (Δ E 01 ) have been determined for the parent (1122.756(3) MHz), DCOOH⋯CBU (1084.538(1) MHz) and HCOOD⋯CBU (1180.282(4) MHz) isotopic species. From these splittings, the potential barrier to interconversion has been calculated to be B 2 = 39.7(5) cm −1 . The tunneling pathway is an asymmetric butterfly-like motion between the two moieties of the adduct, with a barrier at a configuration in which the ring plane of cyclobutanone is coplanar with formic acid.