PMID- 35549287
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20220630
IS  - 1520-5215 (Electronic)
IS  - 1089-5639 (Linking)
VI  - 126
IP  - 20
DP  - 2022 May 26
TI  - Rotational and Vibrational Spectra of the Pyridyl Radicals: A Coupled-Cluster 
      Study.
PG  - 3185-3197
LID - 10.1021/acs.jpca.2c01761 [doi]
AB  - Pyridyl is a prototypical nitrogen-containing aromatic radical that may be a key 
      intermediate in the formation of nitrogen-containing aromatic molecules under 
      astrophysical conditions. On meteorites, a variety of complex molecules with 
      nitrogen-containing rings have been detected with nonterrestrial isotopic 
      abundances, and larger nitrogen-containing polycyclic aromatic hydrocarbons 
      (PANHs) have been proposed to be responsible for certain unidentified infrared 
      emission bands in the interstellar medium. In this work, the three isomers of 
      pyridyl (2-, 3-, and 4-pyridyl) have been investigated with coupled cluster 
      methods. For each species, structures were optimized at the CCSD(T)/cc-pwCVTZ 
      level of theory and force fields were calculated at the CCSD(T)/ANO0 level of 
      theory. Second-order vibrational perturbation theory (VPT2) was used to derive 
      anharmonic vibrational frequencies and vibrationally corrected rotational 
      constants, and resonances among vibrational states below 3500 cm(-1) were treated 
      variationally with the VPT2+K method. The results yield a complete set of 
      spectroscopic parameters needed to simulate the pure rotational spectrum of each 
      isomer, including electron-spin, spin-spin, and nuclear hyperfine interactions, 
      and the calculated hyperfine parameters agree well with the limited available 
      data from electron paramagnetic resonance spectroscopy. For the handful of 
      experimentally measured vibrational frequencies determined from photoelectron 
      spectroscopy and matrix isolation spectroscopy, the typical agreement is 
      comparable to experimental uncertainty. The predicted parameters for rotational 
      spectroscopy reported here can guide new experimental investigations into the 
      yet-unobserved rotational spectra of these radicals.
FAU - Meyer, Kelly S
AU  - Meyer KS
AUID- ORCID: 0000-0001-9999-8015
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
FAU - Westerfield, John H
AU  - Westerfield JH
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
FAU - Johansen, Sommer L
AU  - Johansen SL
AUID- ORCID: 0000-0002-6864-385X
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
FAU - Keane, Jasmine
AU  - Keane J
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
FAU - Wannenmacher, Anna C
AU  - Wannenmacher AC
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
FAU - Crabtree, Kyle N
AU  - Crabtree KN
AUID- ORCID: 0000-0001-5629-5192
AD  - Department of Chemistry, University of California, Davis, One Shields Avenue, 
      Davis, California 95616, United States.
LA  - eng
PT  - Journal Article
DEP - 20220513
PL  - United States
TA  - J Phys Chem A
JT  - The journal of physical chemistry. A
JID - 9890903
SB  - IM
EIN - J Phys Chem A. 2022 Jul 14;126(27):4562. PMID: 35771207
EDAT- 2022/05/14 06:00
MHDA- 2022/05/14 06:01
CRDT- 2022/05/13 11:44
PHST- 2022/05/14 06:00 [pubmed]
PHST- 2022/05/14 06:01 [medline]
PHST- 2022/05/13 11:44 [entrez]
AID - 10.1021/acs.jpca.2c01761 [doi]
PST - ppublish
SO  - J Phys Chem A. 2022 May 26;126(20):3185-3197. doi: 10.1021/acs.jpca.2c01761. Epub 
      2022 May 13.