closo-Halogenohydrohexaborate, III Schwingungsspektren der closo-Halogenohydrohexaborate XnB6H6-n2-, n = 1-5; X = Cl, Br, I / closo-Halogenohydrohexaborate, III Vibrational Spectra of the closo-Halogenohydrohexaborates XnB6H6-n2-, n = 1-5; X = Cl, Br, I

1987 ◽  
Vol 42 (3) ◽  
pp. 293-300 ◽  
Author(s):  
J. Fritze ◽  
W. Preetz
Keyword(s):  
Vibrational Spectra ◽  
Lower Energy ◽  
Weak Coupling ◽  
The Other ◽  
Geometric Isomers ◽  
Nmr Studies ◽  
First Approximation ◽  
Point Groups ◽  
Stretching Vibrations ◽  
Ir And Raman

The IR and Raman spectra of 20 different halogenohydrohexaborates, including pairs of geometric isomers of the series XnB6H6-n2-, X = Cl, Br, I; n = 1-5, have been assigned according to their point groups D4h, C4v, C3v and C2v determined previously by NMR studies. Due to weak coupling, the vibrations are treated separately to a first approximation in terms of internal B6-cage modes on one hand and modes of the substituents against the cage entity on the other hand. Disregarding the splitting by lowered symmetry, depending on the degree of halogenation, all internal modes of the B6 cluster are observed at nearly unchanged positions in the range of 450-1250 cm-1 . The B6-X stretching vibrations, however, exhibit significant shifts to lower energy with increasing mass of substituents

Darstellung und Schwingungsspektren von Alkyl-und Rhodanohydrohexaboraten / Preparation and Vibrational Spectra of Alkyl and Rhodano Hydrohexaborates

1988 ◽  
Vol 43 (10) ◽  
pp. 1327-1331 ◽  
Author(s):  
A Heinrich ◽  
W Preetz
Keyword(s):  
Frequency Shift ◽  
Raman Spectra ◽  
Organic Solvents ◽  
Vibrational Spectra ◽  
High Frequency ◽  
Acidity Constants ◽  
High Frequency Shift ◽  
Basic Solutions ◽  
Stretching Vibrations ◽  
Ir And Raman

Treatment of B6H62- with iodoalkanes and (SCN)2 in organic solvents affords the monosubstituted protonated hexaborates RB6H6-, R = CH3, C2H5< C3H7, C4H9, C8H17 and SCN, respectively. The acidity constants of these weak Brönsted acids range for the alkylated species from 8.8 to 9.6, and for R = SCN the pka value is ~5. From basic solutions the salts Cs2RB6H5 can be precipitated, which show band patterns in the IR and Raman spectra typical for monosubstituted hydrohexaborates. The protonated compounds RB6H6- are distinguished from the corresponding Brönsted bases RB6H52- by a high frequency shift of the BH stretching vibrations in the order of 100 cm-1. For Cs2(SCN)B6H5, S coordination of SCN- is supposed because of the high frequency of νCN: 2144 cm-1.

Die Schwingungsspektren der Silylanionen (SiH3)nSiH⊖3-n und (SiD3)nSiD⊖3-n / Vibrational Spectra of the Silyl Anions (SiH3)nSiH⊖3-n and (SiD3)nSiD⊖3-n

1974 ◽  
Vol 29 (9-10) ◽  
pp. 647-653 ◽  
Author(s):  
Hans Bürger ◽  
Reint Eujen
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Negative Charge ◽  
Lone Pair ◽  
Normal Coordinate Analysis ◽  
Ir And Raman Spectra ◽  
Normal Coordinate ◽  
Normal Vibrations ◽  
Stretching Vibrations ◽  
Ir And Raman

The IR and Raman spectra of SiH3⊖, SiH3SiH2⊖, (SiH3)2SiH⊖, (SiH3)3Si⊖ and their deuterated derivatives have been recorded in HMPT and HMPT-d18 solutions. Most normal vibrations have been identified. The SiH and SiSi stretching vibrations are considerably lower than for analogous silanes and silylphosphines, ∼ 2050 and 1850-1900 cm-1 being characteristic for SiH3 and SiH⊖n groups respectively. The assignments are proved by a normal coordinate analysis, and force constants have been calculated. The negative charge is mainly localized on the trivalent Si atom and the lone pair acts repulsively rather than strengthening the SiSi bond through (p→d)π effects.

The vibrational spectra of 4-pyridone, and its 2,3,5,6-tetradeutero, N-deutero, N-methyl, N-cyano, and 3,5-dihalogeno derivatives. Mixing between C=C and C=O stretching vibrations

1969 ◽  
Vol 22 (12) ◽  
pp. 2581 ◽  
Author(s):  
BD Batts ◽  
E Spinner
Keyword(s):  
Raman Spectra ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Parent Compound ◽  
The Other ◽  
Medium Effects ◽  
Oxide Structure ◽  
Stretching Vibrations ◽  
Electron Withdrawing Substituents

The infrared spectra of the above compounds, and the Raman spectra of the parent compound and its 2,3,5,6-D4, 1-D, and 1-Me derivatives have been determined. The effects of electron-withdrawing substituents, N- methylation, and deuteration on the two intense infrared bands in the 1480-1650 cm-1 region are not compatible with one being a C=O and the other a C=C stretching band. These two vibrations must be extensively mixed; occasionally very pronounced medium effects, which are not straightforward, are observed for one or both of these bands. The spectra are not in accord with a mostly zwitterionic (N-protonated pyrid-4-oxide) structure (II) of 4-pyridone. Band assignments are made for the parent compound.

Schwingungsspektren und Normalkoordinatenanalyse der Bromo-Iodo-Osmate(IV), [OsBrnI6-n]2-, n = 0-6 / Vibrational Spectra and Normal Coordinate Analysis of Bromo-Iodo-Osmates(IV), [OsBrnI6-n]2-, n = 0-6

1992 ◽  
Vol 47 (12) ◽  
pp. 1667-1672 ◽  
Author(s):  
W. Preetz ◽  
M. Manthey
Keyword(s):  
Low Temperature ◽  
Force Field ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Normal Coordinate ◽  
Geometrical Isomers ◽  
Valence Force ◽  
Valence Force Field ◽  
Point Groups ◽  
Ir And Raman

The IR and Raman spectra of the ten bromo-iodo-osmates(IV) [OsBrnI6-n]2-, n = 0-6, including the geometrical isomers for n = 2, 3, 4, have been recorded at low temperature. The vibrational spectra are completely assigned according to point groups Oh, D4h, C4v, C3v, and C2v, as supported by normal coordinate analyses based on a general valence force field. Due to the different trans-influences Br&lt;I in asymmetric axes Br′–Os–I′, the Os–I′ bonds are strengthened and the Os–Br′ bonds are weakened, as indicated by valence force constants, for Os–I′ on average 4% higher and for Os–Br′ 4% lower, as compared with the values calculated for symmetric I–Os–I and Br–Os–Br axes, respectively.

Schwingungsspektren und Normalkoordinatenanalyse der heteroleptischen Halogenohexaborate B6XnY6-n2-, n = 1-5; Χ ≠ Υ = Cl, Br, I / Vibrational Spectra and Normal Coordinate Analysis of the Heteroleptic Halogenohexaborates B6XnY6-n2-, n = 1— 5; Χ ≠ Y = Cl, Br, I

1991 ◽  
Vol 46 (5) ◽  
pp. 602-608 ◽  
Author(s):  
J. Thesing ◽  
M. Stallbaum ◽  
W. Preetz
Keyword(s):  
Potential Energy Distribution ◽  
Site Symmetry ◽  
Geometric Isomers ◽  
Normal Coordinate ◽  
Vibrational Coupling ◽  
Valence Force Field ◽  
Stretching Vibrations ◽  
Ir And Raman ◽  
Ir Bands ◽  
Good Agreement

Normal coordinate analyses for the 24 mixed halogenohexaborates B6XnY6-n2-, n = 1—5, Χ ≠ Y = Cl, Br, I, including the pairs of geometric isomers for n = 2, 3, 4 have been performed, based on a general valence force field. Using the bond lengths and force constants for the homoleptic species B6X62-, which with respect to the B6 cage are weighted standardized, the calculated frequencies are in good agreement with observed IR and Raman bands. The boronhalogen stretching vibrations for symmetric molecular axes correspond with the Ra(IR) bands of the homoleptic compounds: ClB6Cl 327 (515), BrB6Br 207 (430), IB6I 152 (394) cm-1. As a characteristic feature the mixed halogeno clusters exhibit bands with nearly averaged frequencies from asymmetrical axes: ClB6Br 261 (487), ClB6I 227 (473), BrB6I 178 (409) cm-1. This complete vibrational coupling is confirmed by properly balanced potential energy distribution on BX and BY bonds. There is a slight influence of the different substituents on the internal modes of the B6 cage (pseudo-Oh), observed in the sequence A1g&gt;T1u&gt; Eg&gt;T2g in the region 1220-740 cm-1. The bands are shifted about 100 cm-1 with increasing mass of halogen, broadened by boron isotopomers (max. 60 cm-1), and degenerate vibrations are split by lowered point and site symmetry up to 100 cm-1.

closo-Halogenohydrohexaborate, IV Protonierung, Deuterierung und Schwingungsspektren von claso-Hexaboraten / closo-Halogenohydrohexaborate, IV Protonation, Deuteration and Vibrational Spectra of closo-Hexaborates

1988 ◽  
Vol 43 (10) ◽  
pp. 1319-1326 ◽  
Author(s):  
W Preetz ◽  
A Heinrich ◽  
J Thesing
Keyword(s):  
Activation Energy ◽  
Frequency Shift ◽  
Vibrational Spectra ◽  
High Frequency ◽  
Alkaline Solutions ◽  
Lower Symmetry ◽  
High Frequency Shift ◽  
Stretching Vibrations ◽  
Ph Dependent ◽  
Ir And Raman

The weak Brönsted acids B6H7- and XB6H6-, X = Cl, Br, I; pka : 7-4,75, are formed by protonation of B6H62- and XB6H52- respectively. The deuteration rates, evaluated from integrated IR band intensities of the BH and BD stretching vibrations, are linearly dependent on the mole fractions of the protonated species, and decrease with increasing degree of halogenation in the series Cl>Br>I. H atoms trans-positioned to halogens are exchanged 100 times more rapidly than the remaining ones. The activation energy for the H/D exchange amounts to 76 ± 1,5 kJ/mol for B6H7-. The lower symmetry of the protonated borates is evident from additional IR and Raman bands. They are distinguished from the corresponding Brönsted bases by a high frequency shift of the BH stretching vibrations in the order of 100 cm-1. Due to the pH dependent equilibrium B6H62-/B6H7- and different solubilities of the tetrabutylammonium salts, the separation of B6H62-/B12H122- mixtures is achievable. In alkaline solutions the very soluble B6H62- is present, whereas (TBA)2B12H12 precipitates quantitatively. By subsequent cautious acidification of the supernatant, insoluble (TBA)B6H7 is obtained.

Darstellung und Schwingungsspektren von Fluoro-Chloro- Platinaten(IV) einschließlich der Stereoisomeren / Preparation and Vibrational Spectra of Fluoro-Chloro-Platinates(IV) Including Stereoisomers

1989 ◽  
Vol 44 (4) ◽  
pp. 412-418 ◽  
Author(s):  
W. Preetz ◽  
P. Erlhöfer
Keyword(s):  
Ion Exchange ◽  
Vibrational Spectra ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Mixed Ligand ◽  
Trans Isomers ◽  
Trans Effect ◽  
Diethylaminoethyl Cellulose ◽  
Point Groups ◽  
Stretching Vibrations

The reaction of [PtCI6]2- with BrF3 generates the mixed complexes [PtFnC6-n]2- , n = 1- 5, of which the species with n = 2. 3, 4 are cis-configurated. Due to the stronger trans-effect of Cl compared to F, on treatment of [PtF5Cl]2- and cis-[PtF4Cl2]2- with Cl- the trans-isomers are formed stereospecifically. The pure fluoro-chloro-platinates(IV) are separated by ion exchange chromatography on diethylaminoethyl-cellulose. The vibrational spectra o f the mixed ligand complexes are completely assigned according to point groups D4h, C4v, C3v and C2v. The Pt-Cl stretching vibrations of [PtF5Cl]2-, trans-[PtF4Cl2]2-, mer-[PtF3Cl3]2- and [PtFCl5]2- are split by the isotopes 35Cl and 37Cl, showing well resolved sharp Raman lines in the expected ratio of intensities.

scholarly journals Darstellung, schwingungsspektren und Normalkoordinatenanalyse der Bromo-Iodo-Rhenate(IV), [ReRrnI6-n]2-, n = 0-6 / Preparation, vibrational spectra, and normal coordinate analysis of bromo-iodo-rhenates(iv), [ReRrnI6-n]2-, n = 0-6

1994 ◽  
Vol 49 (6) ◽  
pp. 753-758 ◽  
Author(s):  
P. Prillwitz ◽  
W. Preetz
Keyword(s):  
Force Field ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Ir And Raman Spectra ◽  
Normal Coordinate ◽  
Geometrical Isomers ◽  
Valence Force ◽  
Valence Force Field ◽  
Point Groups ◽  
Ir And Raman

The IR and Raman spectra of the ten bromo-iodo-rhenates(IV) [ReBrnI6-n]2-, n = 0 -6 , including the geometrical isomers for n - 2,3,4, have been recorded at 80 K. The vibrational spectra are completely assigned according to point groups Oh, D4h, C4v, C3v, and C2v, as supported by normal coordinate analyses based on a general valence force field. Due to the different mms-influences Br < I in asymmetric axes Br•-Re-I', the Re-I' bonds are strengthened and the Re-Br• bonds are weakened, as indicated by valence force constants, for Re-I' on average 8,5% higher and for Os-Br• 8,3% lower, as compared with the values calculated for symmetric I-Re-I and Br-Re-Br axes, respectively

scholarly journals Schwingungsspektren und Normalkoordinatenanalyse der Chloro-Bromo-Osmate(IV), [OsCl„Br6-n]2-, n = 0-6 / Vibrational Spectra and Normal Coordinate Analysis of Chloro-Bromo-Osmates(IV), [OsCl„Br6-n]2-, n = 0-6

1990 ◽  
Vol 45 (3) ◽  
pp. 283-289 ◽  
Author(s):  
W. Preetz ◽  
K. Irmer
Keyword(s):  
Low Temperature ◽  
Force Field ◽  
Vibrational Spectra ◽  
Normal Coordinate ◽  
Geometrical Isomers ◽  
Valence Force ◽  
Valence Force Field ◽  
Trans Influence ◽  
Point Groups ◽  
Ir And Raman

The IR- and Raman spectra of the ten chloro-bromo-osmates(IV) [OsCl„Br6-n]2-, n = 0-6, including the geometrical isomers for n = 2, 3, 4 have been recorded at low temperature (80 K). The vibrational spectra of these complexes are completely assigned according to point groups Oh, D4h, C4v, C3v and C2v, supported by normal coordinate analyses based on a general valence force field. Due to the stronger trans-influence of Br as compared to Cl, in all asymmetric Cl—Os—Br axes the Os—Br bonds are strengthened and the Os—Cl bonds are weakened, indicated by valence force constants for Os— Br approximately 6% higher, for Os—Cl 6% lower, as compared with the values calculated for symmetrical Br—Os—Br and Cl-Os-Cl axes, respectively. The significantly stronger interaction between opposite bonds is revealed by the stretching interaction constants fdd, which are about three times larger than fdd for bonds at right angles.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

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