Dramatic effect of the nature of R on the intrinsic acidity and basicity of potential astrochemical R–C≡COH and R–C≡CSH compounds

Abstract The effect of changing the nature R substituent from first row (H, Li, BeH, BH 2 , CH 3 NH OH and F) to second (Na, MgH, AlH SiH PH SH Cl) on intrinsic acidity basicity R–C≡COH R–C≡CSH compounds was investigated through use G4 high-level ab initio calculation. variation derivatives as a function is practically parallel that found for corresponding analogs; though basicities former are 9–14% higher than those latter, gap being very small (~ 2%). When this analysis extended in which triple CC bond replaced by double or single bond, it increases systematically goes single; whereas, expected basicity, trend opposite. Quite surprisingly, however, R–C≡CX (X = OH, SH) with first-row substituents, R, remarkably different produced second-row analogs. same observed far acidities concerned. These dissimilarities reflect rather changes strength CX bonds when analog, reflected atoms molecules (AIM), natural orbital (NBO) electron localization (ELF) analyses species.