Quadrupole coupling in alkali metal amides MNH2 (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mrow><mml:msup><mml:mover accent="true"><mml:mi>X</mml:mi><mml:mo stretchy="true">~</mml:mo></mml:mover><mml:mn>1</mml:mn></mml:msup></mml:mrow></mml:math>A1): An experimental and computational study

Burton, Mark; Russ, Benjamin; Bucchino, Matthew P.; Sheridan, P. M.; Ziurys, L. M.

doi:10.1016/j.jms.2019.111211

Cited by 8 publications

(7 citation statements)

References 30 publications

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“…However, AlH 2 OH actually produces a planar geometry unlike hydroxylamine, which has recently been found toward the Galactic Center after decades of searching . Similar bonding has also been observed in related metal amines − and oxides . The floppy nature of AlOH has already been noted, but the present work puts its Al–O bond energy at 128.2 kcal/mol from F12-TZ with ZPVE corrections, slightly stronger than the 126.32 kcal/mol Al–O bond in AlH 2 OH .…”

Section: Resultssupporting

confidence: 70%

Anharmonic Frequencies and Spectroscopic Constants of OAlOH and AlOH: Strong Bonding but Unhindered Motion

2020

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The astrophysical buildup of premineral nanocrystals from atoms to the smallest network-covalent solids will require observations of various small molecules containing the most common elements in minerals including aluminum and oxygen. The present work utilizes high-level quantum chemical quartic force field (QFF) approaches to produce anharmonic vibrational frequencies and spectroscopic constants for such species. The computed B eff for the astrochemically known AlOH molecule at 15780.5 MHz is a mere 40 MHz above the experimental value implying that the B eff for OAlOH at 5580.9 MHz is similarly accurate. The additional 7.31 D dipole moment in OAlOH implies that this molecule is a viable target for interstellar observation. Unlike the other anharmonic vibrational frequencies reported in this work, the Al−O−H bending frequencies in both AlOH and OAlOH are poorly described in the present QFF results. However, this failing actually highlights the fact that these bends are exceptionally floppy yet with counterintuitive exceedingly strong bonding. The Al−O bond energies are 128.2 and 107.2 kcal/mol, respective of AlOH and OAlOH, while the barriers to linearity are meager 16.6 and 380.7 cm −1 (0.1 and 1.1 kcal/mol).

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Section: Resultssupporting

confidence: 70%

Anharmonic Frequencies and Spectroscopic Constants of OAlOH and AlOH: Strong Bonding but Unhindered Motion

2020

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“…The typically pyramidal shape in the amine returns as soon as the Group 14 and higher elements are bonding with the NH 2 . Such behavior has already been observed experimentally as mentioned previously, [12][13][14][15] but these present results show how this is consistent with the same type of behavior in the hydrides containing oxygen.…”

Section: The Exceptions To the Periodic Trendssupporting

confidence: 93%

“…High-resolution rotational spectra of XNH 2 molecules has strongly implied planar structures with C 2v point group symmetries for the relatively simple LiNH 2 , NaNH 2 , KNH 2 , and even •MgNH 2 molecules. [12][13][14][15] The model Hamiltonians necessary to interpret the rotational spectra for these molecules only fit the observed lines if the proper symmetry and a planar geometry are invoked. Li, Na, and K are isovalent with hydrogen and will only form the "single bond" to the NH 2 group according to traditional interpretations of chemical bonding.…”

Section: Introductionmentioning

confidence: 99%

Reduction in Hybridization: Lone Pairs Interacting with Empty p Orbitals

Doerkson¹,

Fortenberry²

2020

Preprint

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<div> <div> <div> <p>X−NH2 and X−OH (for X = Li, BeH, BH2, Na, MgH, and AlH2) exhibit a reduction in hybridization in the N and O atoms, and likely in F, as well. CCSD(T)-F12/cc-pVTZ-F12 optimizations for all combinations of atoms smaller than chlorine (excluding the noble gasses) where the standard valences are filled with hydrogen atoms give breaks in the expected periodic trends. While most bond energies for a given atom increase when bonded to all atoms across a given row in the period table, X−NH2, X−OH, and X−F actually have the strongest bonds with X = BH2 and AlH2. Furthermore, the buildup in bond energy from the alkali to alkaline-earth metals is steady, and the decrease to Group 14 and beyond is also steady. The interactions of X−NH2 and X−OH with X = Li, BeH, BH2, Na, MgH, and AlH2 also produce either linear or fully planar geometries. All of these factors imply that the lone pair on the N or O atoms are datively bonding with the empty <i>p</i> orbitals in the other atoms. This leads to a reduction in hybridization. The non-periodic strengths of these bonds have implications for the detection of molecules in space as well as in models for the formation of refractory molecules and condensation of mineral species in early stages of planet formation. </p> </div> </div> </div>

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“…Planar geometries in the amines (given in Figure S1 of the Supporting Information) and even linear ∠X–O–H angles are present in some cases. The planarity of amines bonded with alkali and alkaline earth metals has been documented experimentally in high-resolution rotational spectra, − and the linearity of hydroxides has been shown computationally . The ionic interactions in these structures pit atoms with the highest charge separation, i.e., the X/Y heavy atoms, together, while the remaining hydrogens are attempting to be as far removed from the opposite monomer as possible.…”

mentioning

confidence: 99%

Coincidence between Bond Strength, Atomic Abundance, and the Composition of Rocky Materials

Doerksen

Fortenberry

2020

ACS Earth Space Chem.

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After removal the geologically and astrophysically underabundant Be, B, and F atoms from consideration, the strongest X−Y bonds in H n X−YH m hydrides are for O bonding with Al, Si, and Mg. These are stronger than the C−C bond in ethane or the C−O bond in methanol, for instance. These atoms, along with Fe, which is not a part of this study, are the dominant elements of rocky bodies and also happen to be the most common elements in the Earth's lithosphere. This study has examined the bond strengths of all H n X−YH m hydrides from Li to Cl, except the noble gas Ne. Hence, this work indicates a possible link between simple hydrides, like HOAlH 2 , and the beginning stages of mineral nanocrystal formation in the early solar system or interstellar grain nucleation. These strong bonds likely arise from notably strong ionic interactions between the third-row atoms with oxygen and may drive the early condensation of refractory materials in astrophysical contexts.

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Quadrupole coupling in alkali metal amides MNH2 (X~1A1): An experimental and computational study

Cited by 8 publications

References 30 publications

Anharmonic Frequencies and Spectroscopic Constants of OAlOH and AlOH: Strong Bonding but Unhindered Motion

Anharmonic Frequencies and Spectroscopic Constants of OAlOH and AlOH: Strong Bonding but Unhindered Motion

Reduction in Hybridization: Lone Pairs Interacting with Empty p Orbitals

Coincidence between Bond Strength, Atomic Abundance, and the Composition of Rocky Materials

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