scholarly journals Reduction in Hybridization: Lone Pairs Interacting with Empty p Orbitals

2020 ◽  
Author(s):  
Edmund Doerkson ◽  
Ryan Fortenberry
Keyword(s):  
Bond Energy ◽  
Alkaline Earth ◽  
Lone Pair ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Bond Energies ◽  
Hydrogen Atoms ◽  
Group 14 ◽  
Atom Increase ◽  
Planar Geometries

<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>

scholarly journals Reduction in Hybridization: Lone Pairs Interacting with Empty p Orbitals

2020 ◽  
Author(s):  
Edmund Doerkson ◽  
Ryan Fortenberry
Keyword(s):  
Bond Energy ◽  
Alkaline Earth ◽  
Lone Pair ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Bond Energies ◽  
Hydrogen Atoms ◽  
Group 14 ◽  
Atom Increase ◽  
Planar Geometries

<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>

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds

1999 ◽  
Vol 55 (2) ◽  
pp. 139-146 ◽  
Author(s):  
V. A. Blatov ◽  
L. V. Pogildyakova ◽  
V. N. Serezhkin
Keyword(s):  
Crystal Structure ◽  
Alkaline Earth ◽  
Organometallic Compounds ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Crystal Chemical ◽  
Coordination Polyhedra ◽  
Coordination Numbers ◽  
Coordination Spheres

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi–Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO n coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M—O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M—O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN \ge 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

Ionization of alkaline earth additives in hydrogen flames - I. Hydrogen atom concentrations and ion stabilities

1974 ◽  
Vol 338 (1613) ◽  
pp. 155-173 ◽  
Keyword(s):  
Alkaline Earth ◽  
Molecular Ions ◽  
The Other ◽  
Hydrogen Atoms ◽  
Ion Hydration ◽  
Atomic Ions ◽  
Charged Species ◽  
Hydration Energies ◽  
Three Body ◽  
Species Being

The ions present in flames of H 2 +O 2 + N 2 with trace quantities of an alkaline earth M ( = Ca or Sr) added to them have been studied mass spectrometrieally. Those detected were principally MOH + and M + , the only negatively charged species being the free electron. It was established that the reaction M + +H 2 O = MOH + +H was rapid enough to be balanced everywhere in a flame. Detailed studies of (I) provided a means for measuring the concentration of hydrogen atoms at the point of sampling in the flame from observations of [M + ]/[MOH + ]. It proved possible to make absolute determinations of [H]. In addition, the ionization potentials of CaOH and SrOH were measured as 5.7 ± 0.3 and 5.4 ± 0.3 eV, which values are slightly less than those for the corresponding alkaline earth atoms. Hydrates of MOH + and M + were observed, but it was concluded that ion-hydration is not an important flame process in this case, but rather one associated with cooling of gases as they are sampled into the mass spectrometer. It appears that molecular ions hydrate in a two-body process, e. g. MOH + + H 2 O → MOH + . H 2 O with a velocity constant, which is independent of temperature and approximately 1 x 10 –10 ml molecule –1 s –1 . Atomic ions on the other hand initially undergo hydration by a slower three-body step requiring a chaperon molecule. The first hydration energies at absolute zero for CaOH + and SrOH + were measured to be 120±20 and 109±15 kJ mol –1 respectively. These exceed the corresponding quantities for Ca + and Sr + , which were found to be 75±16 and 60±16 kJ mol –1 .

Neue Barium-Oxoantimonate(III): Darstellung und Kristallstruktur von Ba3[SbO3]2 und Ba2[Sb2O5]/New Barium Oxoantimonates(III): Synthesis and Crystal Structures of Ba3[SbO3]2 and Ba2[Sb2O5]

2004 ◽  
Vol 59 (5) ◽  
pp. 503-512 ◽  
Author(s):  
Franziska Emmerling ◽  
Sabine Zimper ◽  
Caroline Röhr
Keyword(s):  
Crystal Structures ◽  
Alkaline Earth ◽  
Lone Pair ◽  
Antimony Oxide ◽  
Structure Type ◽  
The Other ◽  
Structure And Bonding ◽  
Lone Pair Electrons

Abstract The barium oxoantimonates(III) Ba3[SbO3]2 (triclinic, P1̄, a = 615.2(8), b = 981.4(3), c = 1215.4(5) pm, α =74.683(9), β =89.710(6), γ =71.464(7)°, Z =2, R1=0.0802) and Ba2[Sb2O5] (orthorhombic, Cmcm, a = 401.0(3), b = 1450.6(7), c = 636.6(6) pm, Z = 4, R1 = 0.0589) have been synthesized from melts of elemental barium and antimony oxide Sb2O3 at a temperature of 800 °C. Their oxoantimonate building units are strongly influenced by the stereochemically active lone pair electrons of the pentele element: In the Ba rich compound Ba3[SbO3]2, isolated ψ tetrahedra [SbO3]3− are present, in Ba2[Sb2O5], which crystallizes with the Sr2Bi2O5 structure type, two of these ψ tetrahedra are condensed to form nucelar units [Sb2O5]4−. The two compounds are compared in terms of structure and bonding with the alkali antimonates on one hand and with the alkaline earth bismutates on the other.

The structural features of a tetrahedral 1,3-monothiolate complex: The crystal and molecular structure of Bis(ethyl 3-mercaptobut-2-enoato)zinc(II)

1977 ◽  
Vol 30 (5) ◽  
pp. 993 ◽  
Author(s):  
BF Hoskins ◽  
CD Pannan
Keyword(s):  
Molecular Structure ◽  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
Lone Pair ◽  
Structural Features ◽  
The Other ◽  
Zinc Atom ◽  
Monoclinic Space Group ◽  
Hydrogen Atoms ◽  
Mean Values

The crystal and molecular structure of bis(ethy 3-mercaptobut-2- enoato)zinc(II) has been determined by single-crystal X-ray diffraction techniques. Solved by conventional Patterson and Fourier methods the structure was refined by a least-squares method employing anisotropic thermal parameters to all non-hydrogen atoms to R and Rw values of 0.040 and 0.046 respectively. The complex crystallizes in the monoclinic space group P21/c with four molecules in a unit cell of dimensions a 11.107(1), b 18.239(2) and c 8.438(1) Ǻ and β 107.7(1)�. The intensities of 2274 independent and statistically significant [I ≥ 3σ(I)] reflections with θ values ≤ 70� were measured by counter methods using nickel- filtered Cu Kα radiation. The crystals comprise discrete monomeric molecules with the zinc atom bonded to two sulphur atoms and two oxygen atoms giving a coordination arrangement which is substantially distorted from an ideal tetrahedron. The mean values for the Zn-S and Zn-O bond distances are 2.247(1) and 2.007(3) Ǻ respectively and the average S-Zn-O intraligand bond angle is 99.25(8)�. The geometries of the ligands differ in two ways. Firstly, the two ethyl groups adopt differing conformations and secondly, while one ligand moiety is essentially planar with the zinc atom displaced about 0.1 Ǻ from that plane, the displaced atom in the other ligand is the carbon bonded to the sulphur atom and not the metal which is, in this instance, coplanar with the other members of the ring. Bond distances in each chelate ring indicate aromatic character with a lone pair of electrons on the ethoxy-oxygen participating in the delocalization.

scholarly journals “Direct”, “Inverted” and “Superdirect” Sigma Bonds: Substituent Angles and Bond Energy. The Case of the CC Bonds in Hydrocarbons.

2020 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Dissociation Energy ◽  
Bond Energy ◽  
Multiple Bond ◽  
The Other ◽  
Hydrogen Atoms ◽  
The Mean ◽  
Sigma Bonds ◽  
Single Bonds ◽  
Sigma Bond

The A-A dissociation energy with respect to geometry frozen fragments (BE) of has been calculated for AHn-AHn models (C2H6, Si2H6, Ge2H6 and N2H4) as a function of  = H-A-A angles. Following a sigmoidal variation, BE decreases rapidly when  decreases to yield “inverted bonds” for  < 90° and finally nearly vanishes. On the contrary BE increases when  increases with respect to the equilibrium value; we propose the term of “superdirect” to qualify such bonds. This behaviour has been qualitatively interpreted in the case of C2H6 by the variation of the overlap of both s+p hybrids. The BE of one C-H bond in CH3 behaves similarly as function of its H-C-H angle with the other three hydrogen atoms. The concept of inverted/direct/superdirect bond is generalized to any CC sigma bond in hydrocarbons and can be characterized by the mean angle value <> of this bond with substituents (multiple-bonded substituents are considered as several substituents). This applies as well to formal single bonds as to sigma bonds in a formally multiple bond. <br>

Comparative accumulation of Alkaline-earth metals by two freshwater Mussel species from the Nepean River, Australia: Consistences and a resolved Paradox

1993 ◽  
Vol 44 (4) ◽  
pp. 609 ◽  
Author(s):  
RA Jeffree ◽  
SJ Markich ◽  
PL Brown
Keyword(s):  
Alkaline Earth ◽  
Tissue Concentration ◽  
Freshwater Mussel ◽  
Dry Weight ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Tissue Concentrations ◽  
South Wales ◽  
Solubility Constant ◽  
The Mean

Whole tissue concentrations of Be, Mg, Ca, Sr, Ba and 226Ra were determined in Hyridella depressa (Lamarck) and Velesunio ambiguus (Philippi) from a minimally polluted region in the Upper Nepean River, New South Wales. Although the mean tissue concentrations of each metal were comparable between the two species, their patterns of accumulation were dissimilar. For each metal, tissue concentration was significantly correlated (P≤0.01) with tissue dry weight and shell length in H. depressa, but not in V. ambiguus, in which variability between individuals was high and Mg concentration was inversely correlated (P≤0.05) with tissue dry weight. However, in each species the Ca concentration was a highly significant (P≤0.001) positive predictor of the concentration of each of the other metals. For each species, normalized rates of accumulation of the metals, relative to increasing Ca concentration and/or size, were 226Ra >Ba≥Sr>Ca > Mg; these rates were inversely related (P≤0.05) to their solubilities as hydrogen phosphates. This inverse relationship was used to predict a solubility constant for BeHPO4. The results were consistent with those previously obtained for V. angasi (Sowerby). The metal solubility relationships, based on the relative increases in the tissue concentrations of each metal over the range of Ca concentrations, held for both species even though V. ambiguus showed no significant (P>0.05) increase in tissue concentrations with size. This paradox can be explained as follows. In both species the Ca tissue concentration is a measure of the total influx and efflux of Ca and its analogues through the tissue of an individual over its lifetime; however, in V. ambiguus this total flux is unrelated to mussel size. The use of Ca concentration to predict concentrations of the other metals was effective in explaining up to 98% and 95% of the variability between individual mussels of H. depressa and V. ambiguus respectively. Hence, the problem of inherent variability between individuals can be eliminated. This will permit any spatial and/or temporal differences in the tissue concentrations of alkaline-earth metals of mussel populations to be more readily discerned.

SKELETAL SILVER CATALYSTS FOR THE OXIDATION OF ETHYLENE TO ETHYLENE OXIDE

1956 ◽  
Vol 34 (5) ◽  
pp. 665-671 ◽  
Author(s):  
A. Cambron ◽  
W. A. Alexander
Keyword(s):  
Ethylene Oxide ◽  
Alkaline Earth ◽  
Specific Activity ◽  
High Specific Activity ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Silver Alloys ◽  
Silver Catalysts

Skeletal silver catalysts of high specific activity have been prepared by the removal of calcium from calcium–silver alloys. The activity of these catalysts in the oxidation of ethylene to ethylene oxide has been investigated. Catalysts prepared by the removal of the other alkaline earth metals from their alloys with silver have also been studied. It has been found that catalysts prepared from calcium–silver alloys show a higher specific activity and are more stable and more conveniently prepared than the catalysts from the other silver alloys investigated.

Synthese und Kristallstrukturen von Diazadien-Komplexen der Erdalkalimetalle / Syntheses and Crystal Structures of Diazadiene Complexes of the Alkaline Earth Metals

1995 ◽  
Vol 50 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Volker Lorenz ◽  
Bernhard Neumüller ◽  
Karl-Heinz Thiele
Keyword(s):  
Crystal Lattice ◽  
Crystal Structures ◽  
Structure Determination ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Calcium Atom ◽  
Space Group ◽  
X Ray ◽  
Moisture Sensitive

(DME)2] 1 (R = C6H4-4-CH3; DME = dimethoxyethane) was prepared by reaction of calcium with NR=CPh-CPh=NR in DME solution. The compound forms orange, moisture sensitive crystals, which were characterized by an X-ray structure determination [space group orthorhombic, P212121, Z = 4, 4634 observed unique reflections, R = 0.046; lattice dimensions at –70 °C: a = 1340.2(3), b = 1528.1(3), c = 1609.1(3) pm]. The calcium atom is coordinated by the four oxygen atoms of two chelating DME molecules and two nitrogen atoms of the diazadiene ligand, bonded in its enediamide form.[Ba2(DME)3(NPh–CPh=CPh–NPh)2 · DME] 3 was obtained from barium metal and NPh=CPh-CPh=NPh in DME solution as red crystals [space group monoclinic, P2l/c, Z = 4, 4000 observed unique reflections, R = 0.166; lattice dimensions at -70 °C: a = 1704.5(3), b = 1786.1(4), c = 2177.4(4) pm, β = 105.98(3)°]. The two barium atoms are bridged by two differently bonded diazadiene ligands (μ2-Ν,Ν′;μ-Ν, σ-Ν′). Additionally, one of the barium atoms is coordinated to two DME molecules and the other one to only one of the ether molecules. A further DME molecule is a constituent of the crystal lattice.

scholarly journals Study of the Interference effects of Aluminium on the Atom- And Ion-Lines of Alkaline Earth Metals in Aqueous Solutions Using an ICP Spectrometer with Axially Viewed Plasma

2015 ◽  
Vol 43 (1) ◽  
pp. 49-54
Author(s):  
Olivér Bánhidi
Keyword(s):  
Inductively Coupled Plasma ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Sample Introduction ◽  
Interference Effects ◽  
Spray Chamber ◽  
Inductively Coupled ◽  
Different Types ◽  
Sample Introduction Devices

Abstract The main advantage of inductively coupled plasma spectrometers with axially viewed plasma relative to the radially viewed plasma is the better detection power. The detection limits of the former are about 5-10 times lower than the latter. On the other hand, the axially viewed plasma has disadvantages. The most notable is the increased number of interference effects. In this paper, the study of the interference effects of aluminium on the atom- and ion-lines of alkaline earth metals are presented by examining different types of sample-introduction devices, such as a simple Meinhart-type concentric nebuliser, a V-groove nebuliser using a Sturman-Masters spray chamber, and an ultrasonic nebuliser

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