Substituted hydrocarbon: a CCSD(T) and local vibrational mode investigation

Substituent effects on the carbon–carbon bonds of hydrocarbons have been a topic interest within past seven decades as resultant information would enable one to tune activity CC bonds. However, current assessments C≡C, C=C, and C−C bond strength acetylene, ethylene, ethane well their derivatives rely indirect measures such length dissociation enthalpy. In this work, we introduce quantitative measure intrinsic for set 40 hydrocarbon systems consisting 3 parent structures, 36 involving CF3, CH3, CHO, F, NH2, or OH groups, conjugated system, based vibrational spectroscopy. Local mode force constants ka(CC) were computed at CCSD(T)/cc-pVTZ level theory 1–32 34–40 CCSD(T)/cc-pVDZ 33. From ka(CC), derived related orders BSO n(CC) in order provide strength. Topological electron density natural population analyses carried out analyze nature these complement measures. For substituted systems, found strengthening/weakening occurs covalent increases/decreases by means varying charge delocalizations. Our findings new guidelines desirably modulating design prospective pathways cleavage reactions.