Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate

Zunwu Zhou, R. Alan Aitken, Charlotte Cardinaud, Alexandra M.Z. Slawin, Honghao Wang, Adam M. Daly, Michael H. Palmer, Stephen G Kukolich

Research output: Contribution to journalArticle

Abstract

An efficient synthesis of formamidinium formate is described. The experimental x-ray structure shows both internal and external H-bonding to surrounding molecules. However, in the gas phase, this compound occurs as a doubly hydrogen bonded dimer between formamidine and formic acid. This doubly hydrogen-bonded structure is quite different from the solid state structure. Microwave spectra were measured in the 6-14 GHz range using a pulsed-beam Fourier transform microwave (MW) spectrometer. The two nonequivalent N-atoms exhibit distinct quadrupole coupling. The rotational, centrifugal distortion, and quadrupole coupling constants determined from the spectra have the following values: A = 5880.05(2), B = 2148.7710(2), C = 1575.23473(13), 1.5 χaa (N1) = 1.715(3), 0.5(χbb-χcc) (N1) = -1.333(4), 1.5 χaa (N2) = 0.381(2), 0.25(χbb-χcc) (N2) = -0.0324(2), and D J = 0.002145(5) MHz. The experimental inertial defect, Δ = -0.243 amu Å 2 , is consistent with a planar structure. Accurate and precise rotational constants (A, B, and C), obtained from the MW measurements, were closely reproduced, within 1%-2% of the measured values, with the M11 DFT theoretical calculations. Detailed comparison of the measured and calculated A, B, and C rotational constants confirms the planar doubly hydrogen bonded structure. The calculated nitrogen quadrupole coupling strengths of the monomer are quite different from either of the two nitrogen sites of the dimer. The poor agreement between measured and calculated quadrupole coupling strengths shows that the dimer is not locked in the equilibrium structure but is likely undergoing large amplitude vibrational motion of the hydrogen atoms moving between the N and O atoms involved in the hydrogen bonding.

Original languageEnglish (US)
Article number094305
JournalJournal of Chemical Physics
Volume150
Issue number9
DOIs
StatePublished - Mar 7 2019

Fingerprint

formic acid
formates
microwave spectra
Hydrogen
quadrupoles
Microwaves
Dimers
X rays
dimers
hydrogen
synthesis
Atoms
Microwave spectrometers
x rays
Nitrogen
Microwave measurement
nitrogen
microwave spectrometers
planar structures
Discrete Fourier transforms

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate. / Zhou, Zunwu; Aitken, R. Alan; Cardinaud, Charlotte; Slawin, Alexandra M.Z.; Wang, Honghao; Daly, Adam M.; Palmer, Michael H.; Kukolich, Stephen G.

In: Journal of Chemical Physics, Vol. 150, No. 9, 094305, 07.03.2019.

Research output: Contribution to journalArticle

Zhou, Zunwu ; Aitken, R. Alan ; Cardinaud, Charlotte ; Slawin, Alexandra M.Z. ; Wang, Honghao ; Daly, Adam M. ; Palmer, Michael H. ; Kukolich, Stephen G. / Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate. In: Journal of Chemical Physics. 2019 ; Vol. 150, No. 9.
@article{f1c152e6c954424aa3dd064c100d8a3e,
title = "Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate",
abstract = "An efficient synthesis of formamidinium formate is described. The experimental x-ray structure shows both internal and external H-bonding to surrounding molecules. However, in the gas phase, this compound occurs as a doubly hydrogen bonded dimer between formamidine and formic acid. This doubly hydrogen-bonded structure is quite different from the solid state structure. Microwave spectra were measured in the 6-14 GHz range using a pulsed-beam Fourier transform microwave (MW) spectrometer. The two nonequivalent N-atoms exhibit distinct quadrupole coupling. The rotational, centrifugal distortion, and quadrupole coupling constants determined from the spectra have the following values: A = 5880.05(2), B = 2148.7710(2), C = 1575.23473(13), 1.5 χaa (N1) = 1.715(3), 0.5(χbb-χcc) (N1) = -1.333(4), 1.5 χaa (N2) = 0.381(2), 0.25(χbb-χcc) (N2) = -0.0324(2), and D J = 0.002145(5) MHz. The experimental inertial defect, Δ = -0.243 amu {\AA} 2 , is consistent with a planar structure. Accurate and precise rotational constants (A, B, and C), obtained from the MW measurements, were closely reproduced, within 1{\%}-2{\%} of the measured values, with the M11 DFT theoretical calculations. Detailed comparison of the measured and calculated A, B, and C rotational constants confirms the planar doubly hydrogen bonded structure. The calculated nitrogen quadrupole coupling strengths of the monomer are quite different from either of the two nitrogen sites of the dimer. The poor agreement between measured and calculated quadrupole coupling strengths shows that the dimer is not locked in the equilibrium structure but is likely undergoing large amplitude vibrational motion of the hydrogen atoms moving between the N and O atoms involved in the hydrogen bonding.",
author = "Zunwu Zhou and Aitken, {R. Alan} and Charlotte Cardinaud and Slawin, {Alexandra M.Z.} and Honghao Wang and Daly, {Adam M.} and Palmer, {Michael H.} and Kukolich, {Stephen G}",
year = "2019",
month = "3",
day = "7",
doi = "10.1063/1.5081683",
language = "English (US)",
volume = "150",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "9",

}

TY - JOUR

T1 - Synthesis, microwave spectra, x-ray structure, and high-level theoretical calculations for formamidinium formate

AU - Zhou, Zunwu

AU - Aitken, R. Alan

AU - Cardinaud, Charlotte

AU - Slawin, Alexandra M.Z.

AU - Wang, Honghao

AU - Daly, Adam M.

AU - Palmer, Michael H.

AU - Kukolich, Stephen G

PY - 2019/3/7

Y1 - 2019/3/7

N2 - An efficient synthesis of formamidinium formate is described. The experimental x-ray structure shows both internal and external H-bonding to surrounding molecules. However, in the gas phase, this compound occurs as a doubly hydrogen bonded dimer between formamidine and formic acid. This doubly hydrogen-bonded structure is quite different from the solid state structure. Microwave spectra were measured in the 6-14 GHz range using a pulsed-beam Fourier transform microwave (MW) spectrometer. The two nonequivalent N-atoms exhibit distinct quadrupole coupling. The rotational, centrifugal distortion, and quadrupole coupling constants determined from the spectra have the following values: A = 5880.05(2), B = 2148.7710(2), C = 1575.23473(13), 1.5 χaa (N1) = 1.715(3), 0.5(χbb-χcc) (N1) = -1.333(4), 1.5 χaa (N2) = 0.381(2), 0.25(χbb-χcc) (N2) = -0.0324(2), and D J = 0.002145(5) MHz. The experimental inertial defect, Δ = -0.243 amu Å 2 , is consistent with a planar structure. Accurate and precise rotational constants (A, B, and C), obtained from the MW measurements, were closely reproduced, within 1%-2% of the measured values, with the M11 DFT theoretical calculations. Detailed comparison of the measured and calculated A, B, and C rotational constants confirms the planar doubly hydrogen bonded structure. The calculated nitrogen quadrupole coupling strengths of the monomer are quite different from either of the two nitrogen sites of the dimer. The poor agreement between measured and calculated quadrupole coupling strengths shows that the dimer is not locked in the equilibrium structure but is likely undergoing large amplitude vibrational motion of the hydrogen atoms moving between the N and O atoms involved in the hydrogen bonding.

AB - An efficient synthesis of formamidinium formate is described. The experimental x-ray structure shows both internal and external H-bonding to surrounding molecules. However, in the gas phase, this compound occurs as a doubly hydrogen bonded dimer between formamidine and formic acid. This doubly hydrogen-bonded structure is quite different from the solid state structure. Microwave spectra were measured in the 6-14 GHz range using a pulsed-beam Fourier transform microwave (MW) spectrometer. The two nonequivalent N-atoms exhibit distinct quadrupole coupling. The rotational, centrifugal distortion, and quadrupole coupling constants determined from the spectra have the following values: A = 5880.05(2), B = 2148.7710(2), C = 1575.23473(13), 1.5 χaa (N1) = 1.715(3), 0.5(χbb-χcc) (N1) = -1.333(4), 1.5 χaa (N2) = 0.381(2), 0.25(χbb-χcc) (N2) = -0.0324(2), and D J = 0.002145(5) MHz. The experimental inertial defect, Δ = -0.243 amu Å 2 , is consistent with a planar structure. Accurate and precise rotational constants (A, B, and C), obtained from the MW measurements, were closely reproduced, within 1%-2% of the measured values, with the M11 DFT theoretical calculations. Detailed comparison of the measured and calculated A, B, and C rotational constants confirms the planar doubly hydrogen bonded structure. The calculated nitrogen quadrupole coupling strengths of the monomer are quite different from either of the two nitrogen sites of the dimer. The poor agreement between measured and calculated quadrupole coupling strengths shows that the dimer is not locked in the equilibrium structure but is likely undergoing large amplitude vibrational motion of the hydrogen atoms moving between the N and O atoms involved in the hydrogen bonding.

UR - http://www.scopus.com/inward/record.url?scp=85062632439&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85062632439&partnerID=8YFLogxK

U2 - 10.1063/1.5081683

DO - 10.1063/1.5081683

M3 - Article

VL - 150

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 9

M1 - 094305

ER -