Naslov
A partial proton transfer in hydrogen bond O–H∙∙∙O in crystals of anhydrous potassium and rubidium complex chloranilates

Autori
Biliškov, Nikola ; Kojić-Prodić, Biserka ; Mali, Gregor ; Molčanov, Krešimir ; Stare, Jernej

Izvornik
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory (1089-5639) 115 (2011), 14; 3154-3166

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
proton transfer ; low-barrier hydrogen bond ; Zundel-like continuum ; IR spectroscopy ; chloranilic acid ; variable-temperature X-ray diffraction ; solid-state NMR ; periodic DFT

Sažetak
Hydrogen bonding and proton transfer in the solid state are studied on the crystals of isostructural anhydrous potassium and rubidium complex chloranilates by variable–temperature single-crystal X-ray diffraction, solid state 1H NMR and IR spectroscopies, and periodic DFT calculations of equilibrium geometries, proton potentials and NMR chemical shifts. Their crystal structures reveal neutral molecules of chloranilic acid and its dianions connected into a chain by O–H∙∙∙O hydrogen bond. A strong hydrogen bond with a large-amplitude movement of the proton with NMR shift of 13 – 17 ppm and a broad continuum in IR spectra between 1000 and 500 cm-1 were observed. Periodic DFT calculations suggest that proton transfer is energetically more favorable if it occurs within a single pair of chloranilate dianion and chloranilic acid molecule, but not continuously along the chains of long periodicity. The calculated chemical shifts confirm the assumption that the weak resonance signals observed at lower magnetic fields pertain to the case when the proton migrates to the acceptor side of the hydrogen bond. The detected situation can be described by a partial proton transfer.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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