Nuclear quadrupole resonance and structure of the dichloride, HCl₂^–, ion

Abstract

Samwzary %C1 quadrupole resonance signals have been observed in eight salts of the HC1,-or DC1,-ion, all of which fall into two classes according as to whether the %C1 frequencies lie near 12 or 20 MHz: the results for CsCl,~(H,O+HCl,-) show that the low frequency signal is associated with a symmetric HC1,-ion, and the small shift observed on deuteriation can be explained in terms of a flat or nearly flat symmetric potential well.

A quantitative ionicity scale for liquid chloride salts

“…25 Such direct and selective identification of distinct chemical environments, at the ionic/ molecular level, is impossible using the more empirical approaches described later (see Ion transport and ionicity). Large V zz gaps recorded experimentally for molecular HCl (no proton transfer), strongly hydrogen bonded HCl (partial proton transfer) and deprotonated Cl À (complete proton transfer) distinguish and characterise each unique chemical environment.…”

“…with HCl reactant), proton transfer was incomplete, the presence of molecular HCl, or, structures involving partial proton donation, would be recorded, via observation of large |C Q |( 35 asymmetric geometries, respectively. 25 Such direct and selective identification of distinct chemical environments, at the ionic/ molecular level, is impossible using the more empirical approaches described later (see Ion transport and ionicity).…”

Solvation Structure and Transport of Acidic Protons in Ionic Liquids: A First-principles Simulation Study

“…In the gas phase, experiments 17 and ab initio calculations 18,19 provided evidence for a linear and symmetric geometry; while in crystals, ClHClis linear but may or may not be centrosymmetric (D ∞V or C ∞V ) depending on the counterion. 14,16,20 In any case, the resulting hydrogen bond (∼100 kJ/mol) 19 is much stronger than that of the neutral dimer HCl‚‚‚ HCl (∼9.5 kJ/mol). 21 In room-temperature molten salts, ClHClis the principal component in the speciation of the proton in mixtures of chloride-or chloroaluminate ILs and HCl.…”

“…The addition of an HCl molecule to [dmim][Cl] led to the immediate formation of hydrogen dichloride, ClHCl - , whose structure stabilized after a few picoseconds. The presence of this anion has been long recognized experimentally, both in liquid and in solid salts containing large cations. − Considering that ClHCl - is one of the simplest hydrogen-bonded systems, much effort has been devoted to its structural and spectroscopic characterization. In the gas phase, experiments and ab initio calculations , provided evidence for a linear and symmetric geometry; while in crystals, ClHCl - is linear but may or may not be centrosymmetric ( D ∞ v or C ∞ v ) depending on the counterion. ,, In any case, the resulting hydrogen bond (∼100 kJ/mol) 19 is much stronger than that of the neutral dimer HCl···HCl (∼9.5 kJ/mol) …”

LVI. Nuclear quadrupole resonance spectroscopy. Part Three. Pulse methods; chemical applications

“…direction, the "Cl frequency at 294°is 11.89 MHz, whereas in NMei+ HCl,-, where this mirror plane is lacking, the "Cl frequency at the same temperature Is 19.51 MHz (59). CsHCb belongs to the 'high-frequency' class (20.47 MHz at 294°) whereas NEt4 + HCl,belongs to the 'low frequency' class (11.89 MHz at, 294°).…”