DFT investigation of coupling constant anomalies in substituted β-lactams

β-lactams are a chemically diverse group of molecules with a wide range of biological activities. Having recently observed curious trends in ²J_HH coupling values in studies on this structural class, we sought to obtain a more comprehensive understanding of these diagnostic NMR parameters, specifically interrogating ¹J_CH, ²J_CH, and ²J_HH, to differentiate 3- and 4-monosubstituted β-lactams. Further investigation using computational chemistry methods was employed to explore the geometric and electronic origins for the observed and calculated differences between the two substitution patterns.