Elucidating heteroatom influence on homonuclear 4J(H, H) coupling constants by DFT/NMR approach. (24th January 2020)

• Record Type: Journal Article
• Authors: Chini, Maria Giovanna; Urbani, Daniele; Dambruoso, Paolo; Riccio, Raffaele; Bifulco, Giuseppe
• Other Names: Sarotti Ariel guestEditor.
• Is Part Of: Magnetic resonance in chemistry. Volume 58:Number 6(2020)
• Page Start: 566
• Page End: 575
• Publication Date: 2020-01-24
• Subjects: 1H -- conformational analysis -- density function theory -- nuclear magnetic resonance -- heteroatoms -- long‐range coupling constant -- organic synthesis; Nuclear magnetic resonance spectroscopy -- Periodicals; Chemistry, Organic -- Periodicals; Magnetic resonance -- Periodicals; 538.36
• DOI: 10.1002/mrc.4983
• Languages: English
• ISSNs: 0749-1581

Abstract

Abstract: We report the structural dependency of long range scalar J ‐coupling constant across four bonds as function of the dihedral angles Φ1 and Φ3. The calculated homonuclear coupling constants 4 J (H, H ), obtained at a density functional theory level, were measured between C(1)─X(2) and X(2)─C(3) bonds in three‐term models, where C, N, O, and S were systematically used as the second atom of the alkyl structures (1 ‐4 ). The 4 J (H, H) calculated values, tabulated for variation of 30° for both Φ1 and Φ3, have disclosed an unexpected detectable coupling constant ( 4 J (H, H ) ≥ 1 Hz) across heteroatoms, useful to provide valuable structural information. A 2‐methyl‐1, 3‐dithiane sulfide (5 ) was used as a case study to prove the applicability and reliability of the calculated values to real issues. The 4 J (H, H ) values obtained at density functional theory for the system 4 have reproduced with good accuracy an unexpected experimental 4 J (H2ax‐H4ax ) = 1.01 Hz of sulfide molecule (5 ), suggesting these calculated coupling constant values as a new powerful tool for the organic synthesis and stereochemical analysis. Abstract : The influence of N, O and S with respect to C atom on 4 J (H, H) coupling constants was evaluated at DFT level. The tabulated long range coupling constants values have disclosed, for each heteroatoms, a series of unexpected NMR measurable 4 J (H, H), generally not observed in a system with only carbon atoms.