High Temperature Chemistry: Stabilities and Structures of High Temperature Species

Hastie, J. W.; Hauge, R. H.; Margrave, John L.

doi:10.1146/annurev.pc.21.100170.002355

Cited by 30 publications

(14 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The few more up-to-date electron diffraction data are quoted in Table 1. Concerning bond angles, there are some estimates from matrix isolation vibrational spectroscopic studies, 27,[29][30][31][32] but they are rather uncertain, considering the shortcomings of the matrix isotope shift technique in determining bond angles. 20a,34 Furthermore, the bond angle estimates from matrix isolation techniques are impacted by matrix effects, which can be considerable for highly flexible molecules with soft bending modes.…”

Section: Resultsmentioning

confidence: 99%

Unusual Dimer Structures of the Heavier Alkaline Earth Dihalides: A Density Functional Study

Levy

Hargittai

2000

J. Phys. Chem. A

View full text Add to dashboard Cite

Density functional theory has been applied to investigate the monomeric and dimeric dihalides of the heavier alkaline earth metals. Quasirelativistic pseudopotentials and large basis sets with uncontracted d (and f) polarization functions on the metals and correlation-consistent all-electron basis sets on the halogens were utilized. The monomers of SrF2, BaF2, and BaCl2 were found to be genuinely bent, while CaF2 and SrCl2, although also bent, have extremely flat potential energy surfaces and are better described as quasilinear. The dimers of the heavier alkaline earth difluorides and dichlorides, Ca2F4, Ca2Cl4, Sr2F4, Sr2Cl4, Ba2F4, and Ba2Cl4, were investigated in great detail. Six different isomers were calculated for the strontium and barium dihalide dimers. The typical D 2 h symmetry halogen-bridged structure is the most stable only for the dimers of the lighter dihalides, and it is not a stable structure for the heavier dimers. For these molecules, a triple-bridged C 3 v symmetry structure is the most stable and even other isomers with pyramidal coordination of the metal were found to be stable, although with higher energy. There appears to be a correlation between the monomer and the dimer structures for alkaline earth dihalides; for the linear halides, the metal tends to have planar, while for the bent ones, pyramidal coordination in their most stable dimer structure. Not only have our calculations extended information on this class of compounds but they have also considerably improved the agreement between the calculated and the available experimental data.

show abstract

Section: Resultsmentioning

confidence: 99%

Unusual Dimer Structures of the Heavier Alkaline Earth Dihalides: A Density Functional Study

Levy

Hargittai

2000

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…Figure 3. Infrared spectra in the 1100-300-cnr1 region for vapor species from pulsed-laser evaporated CaO pellet: (a) CaO evaporated into argon for 2 h, (b) CaO evaporated into kr/Oi = 50/1 for 2.5 h, and (c) after annealing to 25 K.…”

Section: Resultsmentioning

confidence: 99%

Reactions of Pulsed-Laser Evaporated Ca, Sr, and Ba Atoms with O2. Infrared Spectra of the Metal Oxides, Oxide Dimers, Dioxides, and Peroxides in Solid Argon

Andrews¹,

Yustein²,

Thompson³

et al. 1994

J. Phys. Chem.

View full text Add to dashboard Cite

Pulsed-laser ablated Ca, Sr, and Ba atoms have been reacted with 0 2 in excess argon during condensation at 10 K. Infrared spectra and oxygen isotopic substitution show that the major products are the symmetrical OM0 metal dioxide and the rhombic metal oxide dimer. The metal oxides and cyclic M02 peroxides are minor products. In the case of calcium, activation energy provided by pulsed-laser ablation makes the reaction to give CaO, CaO2, (CaO)2, and OCaO possible. Strontium and barium are more reactive and the dioxides and peroxides increase on annealing the argon matrix to 25 K, which shows that no activation energy is necessary for the Sr and Ba atom reactions with 02. Photolysis decreased the peroxide in favor of the dioxide species.The alkaline earth metal peroxides are characterized by 0-0 stretching absorptions in the 700-cm-1 region and are distinctly different from the alkali metal superoxides, which are characterized by 0-0 stretching absorptions in the 1 lOO-cm-' region.

show abstract

“…There is conflicting information in the literature about the shape of these molecules, just as for the transition metal dihalides. ScF 3 was found to be pyramidal by molecular beam deflection, planar by matrix isolation IR, and also planar by quantum chemical calculations. − Chromium trifluoride is planar according to ESR, ,252b IR, and Raman spectroscopy 255 and a recent quantum chemical calculation, while it is pyramidal by other quantum chemical studies. , Both CrCl 3 and CrBr 3 are found to be planar by some spectroscopic studies, , while a gas-phase IR study of CrCl 3 suggests a pyramidal geometry .…”

Section: Transition Metal Trihalides1 First- and Second-row Trihalidesmentioning

confidence: 96%

“…Titanium trihalides are unstable, and their direct heating leads to disproportionation to TiCl 4 (g) and TiCl 2 (s), with the vapor composition strongly depending on its temperature. It has been shown 254 that the IR spectra, attributed earlier to TiF 3 and TiF 2 species, were, in fact, due to TiF 4 and TiF 3 , respectively. The evaporation of chromium trichloride produces tetra-, tri-, and dihalides in the vapor, depending on the temperature, ,, and the situation is similar for chromium tribromide, for which even a small amount of Cr 2 Br 6 was also detected in the vapor. 251b, …”

Section: Transition Metal Trihalides1 First- and Second-row Trihalidesmentioning

confidence: 99%

Molecular Structure of Metal Halides

2000

View full text Add to dashboard Cite

High Temperature Chemistry: Stabilities and Structures of High Temperature Species

Cited by 30 publications

References 91 publications

Unusual Dimer Structures of the Heavier Alkaline Earth Dihalides: A Density Functional Study

Unusual Dimer Structures of the Heavier Alkaline Earth Dihalides: A Density Functional Study

Reactions of Pulsed-Laser Evaporated Ca, Sr, and Ba Atoms with O2. Infrared Spectra of the Metal Oxides, Oxide Dimers, Dioxides, and Peroxides in Solid Argon

Molecular Structure of Metal Halides

Contact Info

Product

Resources

About