Rotational spectroscopy of singly 13C substituted isotopomers of propyne and determination of a semi-empirical equilibrium structure

Müller, H. S. P.; Thorwirth, Sven; Lewen, Frank

doi:10.1016/j.molstruc.2020.127769

Cited by 3 publications

(1 citation statement)

References 81 publications

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“…Attention has been primarily focused in extending the database with species formed by biochemically relevant elements. Specifically, in addition to propyne, 12 nitrogen- and/or oxygen-bearing molecules have been added (HNO, NH 2 OH, CH 2 NH, CH 2 NOH, CO 2 , succinic anhydride, phenol, oxazole, isoxazole, glycidol, cyclopropenone, and glycine) and the number of sulfur compounds has been increased substantially with the inclusion of sulfur dioxide, dimethyl sulfide, dimethyl sulfoxide, sulfinylmethane, hydrogen disulfide, diallyl disulfide, and diphenyl disulfide, with the last three molecules involving a sulfur–sulfur bridge. Since phosphorus is a biologically relevant element not represented in the database, efforts have been made to overcome this limit, resulting in the inclusion of the PH 3 , CH 3 CP, CH 2 PH, and HPO molecules for which an accurate SE equilibrium geometry has been worked out in the literature.…”

Section: Resultsmentioning

confidence: 99%

Accurate Biomolecular Structures by the Nano-LEGO Approach: Pick the Bricks and Build Your Geometry

Ceselin

Barone

Tasinato

2021

J. Chem. Theory Comput.

153

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The determination of accurate equilibrium molecular structures plays a fundamental role for understanding many physical–chemical properties of molecules, ranging from the precise evaluation of the electronic structure to the analysis of the role played by dynamical and environmental effects in tuning their overall behavior. For small semi-rigid systems in the gas phase, state-of-the-art quantum chemical computations rival the most sophisticated experimental (from, for example, high-resolution spectroscopy) results. For larger molecules, more effective computational approaches must be devised. To this end, we have further enlarged the compilation of available semi-experimental (SE) equilibrium structures, now covering the most important fragments containing H, B, C, N, O, F, P, S, and Cl atoms collected in the new SE100 database. Next, comparison with geometries optimized by methods rooted in the density functional theory showed that the already remarkable results delivered by PW6B95 and, especially, rev-DSDPBEP86 functionals can be further improved by a linear regression (LR) approach. Use of template fragments (taken from the SE100 library) together with LR estimates for the missing interfragment parameters paves the route toward accurate structures of large molecules, as witnessed by the very small deviations between computed and experimental rotational constants. The whole approach has been implemented in a user-friendly tool, termed nano-LEGO, and applied to a number of demanding case studies.

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Section: Resultsmentioning

confidence: 99%

Accurate Biomolecular Structures by the Nano-LEGO Approach: Pick the Bricks and Build Your Geometry

Ceselin

Barone

Tasinato

2021

J. Chem. Theory Comput.

153

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Database with Equilibrium Structures of Free Molecules

Vogt,

Demaison

2023

Lecture Notes in Chemistry

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Direct Probes of π-Delocalization in Prototypical Resonance-Stabilized Radicals: Hyperfine-Resolved Microwave Spectroscopy of Isotopic Propargyl and Cyanomethyl

Changala,

Franke,

Stanton

et al. 2024

J. Am. Chem. Soc.

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Delocalization of the unpaired electron in πconjugated radicals has profound implications for their chemistry, but direct and quantitative characterization of this electronic structure in isolated molecules remains challenging. We apply hyperfine-resolved microwave rotational spectroscopy to rigorously probe π-delocalization in propargyl, CH 2 CCH, a prototypical resonance-stabilized radical and key reactive intermediate. Using the spectroscopic constants derived from the high-resolution cavity Fourier transform microwave measurements of an exhaustive set of 13 C-and 2 H-substituted isotopologues, together with high-level ab initio calculations of zero-point vibrational effects, we derive its precise semiexperimental equilibrium geometry and quantitatively characterize the spatial distribution of its unpaired electron. Our results highlight the importance of considering both spin-polarization and orbital-following contributions when interpreting the isotropic hyperfine coupling constants of π radicals. These physical insights are strengthened by a parallel analysis of the isoelectronic species cyanomethyl, CH 2 CN, using new 13 C measurements also reported in this work. A detailed comparison of the structure and electronic properties of propargyl, cyanomethyl, and other closely related species allows us to correlate trends in their chemical bonding and electronic structure with critical changes in their reactivity and thermochemistry.

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Rotational spectroscopy of singly 13C substituted isotopomers of propyne and determination of a semi-empirical equilibrium structure

Cited by 3 publications

References 81 publications

Accurate Biomolecular Structures by the Nano-LEGO Approach: Pick the Bricks and Build Your Geometry

Accurate Biomolecular Structures by the Nano-LEGO Approach: Pick the Bricks and Build Your Geometry

Database with Equilibrium Structures of Free Molecules

Direct Probes of π-Delocalization in Prototypical Resonance-Stabilized Radicals: Hyperfine-Resolved Microwave Spectroscopy of Isotopic Propargyl and Cyanomethyl

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