Absolute <sup>13</sup>C nuclear magnetic shielding of simple isolated molecules from gas phase measurements

Makulski, Włodzimierz

doi:10.1039/d2cp00231k

Cited by 3 publications

(3 citation statements)

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“…9 ppm) but continuous decrease in the observed NMR 13 C chemical shifts of the CO 2 ligand from II LiHMDS ’ to 2 – 15C5′ (from 183.7 to 174.4 ppm, Table S4), overestimating the overall experimental spread by ~4 ppm. These shifts are substantially larger than the computed (experimental) shift of free CO 2 , 124 ppm (126 ppm) [62] . Further analyses indicate that the shift decrease correlates with a small but continuous increase of the computed Ni−C distances by 0.02 Å (1.79 to 1.81 Å, Table S5), and a concomitant decrease of the cumulative negative NPA charge on the η 2 ‐CO 2 moiety by ~0.14 a.u.…”

Section: Resultsmentioning

confidence: 62%

“…These shifts are substantially larger than the computed (experimental) shift of free CO 2 , 124 ppm (126 ppm). [62] Further analyses indicate that the shift decrease correlates with a small but continuous increase of the computed NiÀ C distances by 0.02 Å (1.79 to 1.81 Å, Table S5), and a concomitant decrease of the cumulative negative NPA charge on the η 2 -CO 2 moiety by ~0.14 a.u. (from À 1.06 a.u.…”

Section: Computational Study On ν Co2 and δ 13 C Co2 Valuesmentioning

confidence: 96%

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Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Wolff,

Pelmenschikov,

Müller

et al. 2024

Chemistry A European J

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Nickel complexes with a two‐electron reduced CO2 ligand (CO22–, “carbonite”) are investigated with regard to the influence alkali metal (AM) ions have as Lewis acids on the activation of the CO2 entity. For this purpose complexes with NiII(CO2)AM (AM = Li, Na, K) moieties were accessed via deprotonation of nickel‐formate compounds with (AM)N(iPr)2. It was found that not only the nature of the AM ions in vicinity to CO2 affect the activation, but also the number and the ligation of a given AM. To this end the effects of added (AM)N(R)2, THF, open and closed polyethers as well as cryptands were systematically studied. In 14 cases the products were characterized by X‐ray diffraction and correlations with the situation in solution were made. The more the AM ions get detached from the carbonite ligand, the lower is the degree of aggregation. At the same time the extent of CO2 activation is decreased as indicated by the structural and spectroscopic analysis and reactivity studies. Accompanying DFT studies showed that the coordinating AM Lewis acidic fragment withdraws only a small amount of charge from the carbonite moiety, but it also affects the internal charge equilibration between the LtBuNi and carbonite moieties.

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Section: Resultsmentioning

confidence: 62%

Section: Computational Study On ν Co2 and δ 13 C Co2 Valuesmentioning

confidence: 96%

Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Wolff,

Pelmenschikov,

Müller

et al. 2024

Chemistry A European J

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“…Such studies are important for providing absolute nuclear magnetic shieldings and magnetic moments of small molecules diluted in an inert gas. Makulski 162 reported on absolute 13 C nuclear magnetic shielding of simple isolated molecules from gas phase measurements. Makulski and Godlewski 163 also performed multinuclear NMR studies of various ethanol isotopic forms in the liquid and gas phase.…”

Section: Nuclear Shielding Calculation In Natural Productsmentioning

confidence: 99%

Theory and computation of nuclear shielding

2023

Nuclear Magnetic Resonance

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This chapter continues earlier reviews of essential works on theoretical issues of nuclear magnetic shieldings published from 1 January to 31 December 2022. As previously, the chapter concentrates on theoretical calculations of nuclear shielding parameters and/or chemical shifts in case of free molecules in the gas phase and solution, and in some cases in the solid state using a periodic formulation. The nuclear shieldings in solution are mainly calculated using inexpensive polarizable continuum model of solvent (PCM). The use of discrete solvent molecules (in particular water and other polar solvents), which is essential for correct description of hydrogen bonding, is often omitted by numerous authors. Most calculations use a relatively simple and fast, but reliable density functional theory (DFT) combined with gauge-including atomic orbital (GIAO) approach. On the other hand, reports on prediction of nuclear magnetic shielding parameters using high level theoretical methods combined with large and flexible basis sets are not so common due to the enormous computational cost. In addition, correction of raw theoretical nuclear magnetic shieldings due to ro-vibration (zero-point vibration correction, ZPVC) and temperature corrections (TC), as well as implicit and explicit solvent effects and relativistic corrections are not often reported.

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A new double-reference correction scheme for accurate and efficient computation of NMR chemical shieldings

Crittenden

2022

Phys. Chem. Chem. Phys.

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Absolute ¹³C nuclear magnetic shielding of simple isolated molecules from gas phase measurements

Abstract: The new experimental value of 13C absolute shielding constant in an isolated 13CO molecule was evaluated from the 13C and 3He gas phase NMR measurements performed for 3He/13CO mixtures. The...

Cited by 3 publications

References 53 publications

Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Theory and computation of nuclear shielding

A new double-reference correction scheme for accurate and efficient computation of NMR chemical shieldings

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Absolute 13C nuclear magnetic shielding of simple isolated molecules from gas phase measurements

Abstract: The new experimental value of 13C absolute shielding constant in an isolated 13CO molecule was evaluated from the 13C and 3He gas phase NMR measurements performed for 3He/13CO mixtures. The...

Cited by 3 publications

References 53 publications

Controlling the Activation at NiII−CO22− Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Controlling the Activation at NiII−CO22− Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Theory and computation of nuclear shielding

A new double-reference correction scheme for accurate and efficient computation of NMR chemical shieldings

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Product

Resources

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Absolute ¹³C nuclear magnetic shielding of simple isolated molecules from gas phase measurements

Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere

Controlling the Activation at Ni^II−CO₂²⁻ Moieties through Lewis Acid Interactions in the Second Coordination Sphere