Confirmation of gaseous methanediol from state-of-the-art theoretical rovibrational characterization

Davis, Megan C.; Garrett, Noah; Fortenberry, Ryan C.

doi:10.1039/d2cp02076a

Cited by 7 publications

(9 citation statements)

References 47 publications

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“…However, while both formaldehyde and formic acid are exceptionally stable molecules and building blocks of organic chemistry, the diol form (carbonic acid, CO 3 H 2 ), is notoriously unstable and has required modern analysis for characterization. , Case in point, the proper phase of the solid form of carbonic acid has only recently been clearly established. , Hence, the seemingly straightforward form of carbonic acid that fulfills all of the expectations for p-block and organic chemistry has remained either elusive or unclear, even recently. A similar and simpler diol, methanediol, has only been clearly observed within the past year in the gas phase, enhanced by theoretical confirmation. − As such and besides a few successes, the modern experimental production of carbonic acid under physical conditions similar to those found in nature has been stymied by its high reactivity and proclivity to remain as its painfully stable substituents: water and CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Red-Shifting the Excitation Energy of Carbonic Acid Clusters Via Nonminimum Structures

et al. 2023

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Nonminimum carbonic acid clusters provide excitation energies and oscillator strengths in line with observed ice-phase UV absorptions better than traditional optimized minima. This equation-of-motion coupled cluster quantum chemical analysis on carbonic acid monomers and dimers shows that shifts to the dihedral angle for the internal heavy atoms in the monomer produce UV electronic excitations close to 200 nm with oscillator strengths that would produce observable features. This τ(OCOO) dihedral is actually a relatively floppy motion unlike what is often expected for sp2 carbons and can be distorted by 30° away from equilibrium for an energy cost of only 11 kcal/mol. As this dihedral decreases beyond 30°, the excitation energies decrease further. The oscillator strengths do, as well, but only to a point. Hence, the lower-energy distortions of τ(OCOO) are sufficient to produce structures that exhibit excitation energies and oscillator strengths that would red-shift observed spectra of carbonic acid ices away from the highest UV absorption feature at 139 nm. Such data imply that colder temperatures (20 K) in the experimental treatment of carbonic acid ices are freezing these structures out after annealing, whereas the warmer temperature experiments (80 K) are not.

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Section: Introductionmentioning

confidence: 99%

Red-Shifting the Excitation Energy of Carbonic Acid Clusters Via Nonminimum Structures

et al. 2023

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“…Additionally, there is a greater decrease in computational cost for the larger, less symmetric molecules as shown in Table 3. The largest molecule in this test set is a seven‐atom

C_{2}

molecule (CH

_{2}

(OH)

_{2}

) [135,137] which at the F12‐TcCR+TZ level of theory took 29.90% of the 34382784.77 s for F12b‐TcCR. This greater decrease in computational time for larger, less symmetric molecules is especially significant for allowing the theoretical study of molecules of growing interest for astrochemical observation or even simply laboratory experimental classification.…”

Section: Resultsmentioning

confidence: 99%

“…The citations for the literature values are in Table 1. Previous computational data for C

_{2}

^{-}

c

‐C

_{3}

_{2}

, H

_{2}

CO, H

_{2}

O, HCN, HCO

^{+}

, HMgNC, HNC, HNO, HOCN, HOCO

^{+}

c

‐HOCO,

t

‐HOCO, HPSi, HSO, HSS, NH

_{2}^{-}

, NH

_{3}

, NNOH

^{+}

, and

c

‐SiC

_{2}

all come from reference [48] and CH

_{2}

(OH)

_{2}

comes from references [134] and [135].…”

Section: Computational Detailsmentioning

confidence: 99%

The performance of hybrid and F12∗/F12c explicitly correlated coupled cluster methods for use in anharmonic vibrational frequency computations

Watrous,

Westbrook,

Fortenberry

2023

Int J of Quantum Chemistry

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A hybrid quartic force field approach produces the same accuracies as non‐hybrid methods but for less than one quarter of the computational time. This method utilizes explicitly correlated coupled cluster theory at the singles and doubles level inclusive of perturbative triples (CCSD(T)‐F12b) in conjunction with a triple‐ basis set, core electron correlation, and scalar relativity for the harmonic terms and CCSD(T)‐F12b with a valence double‐ basis set for the cubic and quartic terms. There is no sacrifice in the prediction of fundamental anharmonic vibrational frequencies or vibrationally‐averaged rotational constants as compared to experiment, but the time saved is notable. Other hybrid methods are examined involving different sizes of basis sets and composite terms included or excluded. Not one is more accurate; only one is faster. F12 (also called F12c) is tested as well, but it has an increase in computational time for no increase in accuracy. As such, this work reports a hybrid and composite approach (F12‐TcCR+DZ) in the computation of rovibrational spectral data which can be applied to the observation of novel molecules in the gas phase in the laboratory and potentially even in astrophysical environments.

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“…These electronic energies are conjoined to a quartic force field (QFF), a fourth-order Taylor series expansion of the potential portion of the internuclear Watson Hamiltonian (Fortenberry & Lee 2019. This so-called F12-TcCR (for explicitly correlated, triple−ζ, core-correlating, relativistic) QFF has been shown to provide exceptional accuracy for comparison to known experimental standards, often to within 1.0 cm −1 or better for organic molecules, including the related methanediol where this method confirmed its gas-phase synthesis (Zhu et al 2011;Westbrook & Fortenberry 2020;Jian et al 2021;Watrous et al 2021;Davis et al 2022). Furthermore, IR emission can also now be computed to high accuracy and done so in full cascade (Mackie et al 2018b) in order to provide a clear comparison to JWST observations.…”

Section: Introductionmentioning

confidence: 95%

Toward the IR Detection of Carbonic Acid: Absorption and Emission Spectra

Fortenberry,

Esposito

2024

ApJ

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With the recent radioastronomical detection of cis-trans-carbonic acid (H2CO3) in a molecular cloud toward the Galactic center, the more stable but currently unobserved cis-cis conformer is shown here to have strong IR features. While the higher-energy cis-trans-carbonic acid was detected at millimeter and centimeter wavelengths, owing to its larger dipole moment, the vibrational structure of cis-cis-carbonic acid is more amenable to its observation at micron wavelengths. Even so, both conformers have relatively large IR intensities, and some of these fall in regions not dominated by polycyclic aromatic hydrocarbons. Water features may inhibit observation near the 2.75 μm hydride stretches, but other vibrational fundamentals and even overtones in the 5.5–6.0 μm range may be discernible with JWST data. This work has employed high-level, accurately benchmarked quantum chemical anharmonic procedures to compute exceptionally accurate rotational spectroscopic data compared to experiment. Such performance implies that the IR absorption and even cascade emission spectral features computed in this work should be accurate and will provide the needed reference for observation of either carbonic acid conformer in various astronomical environments.

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Confirmation of gaseous methanediol from state-of-the-art theoretical rovibrational characterization

Abstract: High–level rovibrational characterization of methanediol, the simplest geminal diol, using state-of- the-art, purely ab initio techniques unequivocally confirms previously reported gas phase preparation of this simplest geminal diol in its...

Cited by 7 publications

References 47 publications

Red-Shifting the Excitation Energy of Carbonic Acid Clusters Via Nonminimum Structures

Red-Shifting the Excitation Energy of Carbonic Acid Clusters Via Nonminimum Structures

The performance of hybrid and F12∗/F12c explicitly correlated coupled cluster methods for use in anharmonic vibrational frequency computations

Toward the IR Detection of Carbonic Acid: Absorption and Emission Spectra

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