H/D isotope effects on the geometry and infrared spectrum of the protonated ammonia dimer

Yang, Yonggang; Kühn, Oliver

doi:10.1016/j.cplett.2011.01.076

Cited by 18 publications

(7 citation statements)

References 24 publications

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“…In the former dimer the asymmertic stretching vibrations of the shared protons is shifted to 374 cm −1 , while the N•••N distance is above 2.65 Å. 55,56 This geometry is close to a value of 2.636 Å in the proton-bound homodimer of trimethylamine. 57 A similar trend was observed in protonated tertiary diamines.…”

Section: ■ Discussionmentioning

confidence: 79%

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

et al. 2014

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Hydrogen bond geometries in the proton-bound homodimers of ortho-unsubstituted and ortho-methylsubstituted pyridine derivatives in aprotic polar solution were estimated using experimental NMR data. Within the series of homodimers studied the hydrogen bond lengths depend on the proton affinity of pyridines and--at least for the ortho-methylsubstituted pyridines--on the pKa of the conjugate acids in an approximately quadratic manner. The shortest possible hydrogen bond in the homodimers of ortho-unsubstituted pyridines is characterized by the N···N distance of 2.613 Å. Steric repulsion between the methyl groups of the ortho-methylsubstituted pyridines becomes operative at an N···N distance of ∼2.7 Å and limits the closest approach to 2.665 Å.

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Section: ■ Discussionmentioning

confidence: 79%

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

et al. 2014

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“…In addition, restricted dimensionality (D) quantum calculations were performed in 4D 27 and 6D. 28,29 The PTM was found to shift all the way to 471 cm −1 by the 6D model, 28 close to the experimental value. In addition, absorption bands for the umbrella mode and NH*N bending were assigned, while other fundamental modes remain unassigned.…”

Section: ■ Introductionmentioning

confidence: 61%

Complete Assignment of the Infrared Spectrum of the Gas-Phase Protonated Ammonia Dimer

Wang

Agmon

2016

J. Phys. Chem. A

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The infrared (IR) spectrum of the ammoniated ammonium dimer is more complex than those of the larger protonated ammonia clusters due to close-lying fundamental and combination bands and possible Fermi resonances (FR). To date, the only theoretical analysis involved partial dimensionality quantum nuclear dynamic simulations, assuming a symmetric structure (D3d) with the proton midway between the two nitrogen atoms. Here we report an extensive study of the less symmetric (C3v) dimer, utilizing both second order vibrational perturbation theory (VPT2) and ab initio molecular dynamics (AIMD), from which we calculated the Fourier transform (FT) of the dipole-moment autocorrelation function (DACF). The resultant IR spectrum was assigned using FTed velocity autocorrelation functions (VACFs) of several interatomic distances and angles. At 50 K, we have been able to assign all 21 AIMD fundamentals, in reasonable agreement with MP2-based VPT2, about 30 AIMD combination bands, and a difference band. The combinations involve a wag or the NN stretch as one of the components, and appear to follow symmetry selection rules. On this basis, we suggest possible assignments of the experimental spectrum. The VACF-analysis revealed two possible FR bands, one of which is the strongest peak in the computed spectrum. Raising the temperature to 180 K eliminated the "proton transfer mode" (PTM) fundamental, and reduced the number of observed combination bands and FRs. With increasing temperature, fundamentals red-shift, and the doubly degenerate wags exhibit larger anharmonic splittings in their VACF bending spectra. We have repeated the analysis for the H3ND(+)NH3 isotopologue, finding that it has a simplified spectrum, with all the strong peaks being fundamentals. Experimental study of this isotopologue may thus provide a good starting point for disentangling the N2H7(+) spectrum.

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“…3,6,7,14,20,22,25,29 On the other hand, quantum chemical computations of H + (NH 3 ) 2 predict only the Egen type structure, in which the excess proton is localized at one of the ammonia molecules, and the Zundel type structure is a transient state between the two equivalent Eigen minima. 39,42–48,51–54,56–58 However, H + (NH 3 ) 2 actually forms the Zundel type structure because of the zero point energy over the barrier and the resulting quantum mechanical symmstrization. 41,44,51–54 Also in the present case of H + (DMA) 4 , stable Zundel type isomers (potential minima) were not found in our structure search; even if we start with Zundel type initial forms, they are transformed into the Eigen type during the optimization.…”

Section: Resultsmentioning

confidence: 99%

“…, hydrogen bond (H-bond) networks around an excess proton). 1–59 H-bond coordination numbers of the protonated site and solvent molecules are a key to qualitatively understanding network motifs. For example, water has two OH bonds (proton donors) and two lone pairs (proton acceptors) and acts as a 4-coordinated site (double acceptor-double donor, AADD) at the maximum coordination in H-bond networks.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen bond network structures of protonated dimethylamine clusters H⁺(DMA)_n (n = 3–7)

Mizuide,

Fujii

2024

Phys. Chem. Chem. Phys.

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H/D isotope effects on the geometry and infrared spectrum of the protonated ammonia dimer

Cited by 18 publications

References 24 publications

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

Complete Assignment of the Infrared Spectrum of the Gas-Phase Protonated Ammonia Dimer

Hydrogen bond network structures of protonated dimethylamine clusters H⁺(DMA)_n (n = 3–7)

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H/D isotope effects on the geometry and infrared spectrum of the protonated ammonia dimer

Cited by 18 publications

References 24 publications

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

How Short is the Strongest Hydrogen Bond in the Proton-Bound Homodimers of Pyridine Derivatives?

Complete Assignment of the Infrared Spectrum of the Gas-Phase Protonated Ammonia Dimer

Hydrogen bond network structures of protonated dimethylamine clusters H+(DMA)n (n = 3–7)

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Hydrogen bond network structures of protonated dimethylamine clusters H⁺(DMA)_n (n = 3–7)