Abstract: Using infrared (IR) spectroscopy and density functional theory (DFT) calculations, interaction of CO with the strongest known pure Bronsted carborane superacids, H(CHB(11)Hal(11)) (Hal = F, Cl), was studied. CO readily interacted at room temperature with H(CHB11F11) acid, forming a mixture of bulk salts of formyl and isoformyl cations, which were in equilibrium An(-)center dot center dot center dot H+CO <- COH+center dot center dot center dot An(-). The bonding of CO to the surface Bronsted centers of the weaker acid, H(CHB11Cl11), resulted in breaking of the bridged H-bonds of the acid polymers without proton transfer (PT) to CO. The binding occurred via the C atom (blue shift Delta nu CO up to +155-167 cm(-1), without PT) or via O atom (red shift Delta nu CO up to -110 cm(-1), without PT) always simultaneously, regardless of whether H+ is transferred to CO. IR spectra of all species were interpreted by B3LYP/cc-pVQZ calculations of the simple models, which adequately mimic the ability of carborane acids to form L center dot center dot center dot H+CO, LH+center dot center dot center dot CO, COH+center dot center dot center dot L, and CO center dot center dot center dot H+L compounds (L = bases). The CO bond in all compounds was triple. Acidic strength of the Bronsted centers of commonly used acid catalysts, even so-called superacidic catalysts, is not sufficient for the formation of the compounds studied.

Cite: Stoyanov E.S. , Malykhin S.E.
Carbon monoxide protonation in condensed phases and bonding to surface superacidic Bronsted centers
Physical Chemistry Chemical Physics. 2016. V.18. N6. P.4871-4880. DOI: 10.1039/c5cp07441j WOS Scopus

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Web of science	WOS:000369509100072
Scopus	2-s2.0-84957560257
OpenAlex	W2235502827

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