Infrared Spectra of Solid and Matrix-Isolated (CH3)3N, (CD3)3N, and (SiH3)3N

Goldfarb, Theodore D.; Khare, B. N.

doi:10.1063/1.1841226

Cited by 52 publications

(17 citation statements)

References 14 publications

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“…An analogous calculation for N(SiH 3 ) 3 gives an almost identical value for F unsc (⊥) (0.1292 aJ), accompanied by an out-of-plane bending frequency of 206 cm -1 . The actual frequency will be substantially less than this, in contrast to earlier estimates of 312 and 434 cm -1 …”

Section: Resultscontrasting

confidence: 68%

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Fleischer

McKean

1999

J. Phys. Chem. A

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The structures of hexachlorodisilazane, NH(SiCl3)2, and hexamethyldisilazane, NH(SiMe3)2, have been calculated at HF/6-31G* and MP2/6-31G* levels. Both contain planar HNSi2 skeletons and show the expected staggering of the substituents as seen along the Si···Si direction, as previously found in the electron diffraction structure of the hexamethyl compound. Unlike the latter, however, the ab initio structures both belong to the C 2 point group. Force fields for these two molecules and for tetrachlorodisilazane, NH(SiHCl2)2, were calculated at the HF level and scaled to produce vibration frequencies for comparison with previously obtained spectra. For NH(SiCl3)2, all but five of the fundamentals are satisfactorily assigned. Seven scale factors could be refined, other factors being transferred from model compounds. For the hexamethyl compound, the interpretation was less detailed. In all three molecules the out-of-plane NH bending motion is found to be associated with fundamentals around or below 400 cm-1, far lower than previous assignments. The force constant for this motion is greatly reduced as chlorine substituents are replaced by methyl groups, which shows the sensitivity of the stability of the planar system to the inductive effect of substituents. For tetrachlorodisilazane, NH(SiHCl2)2, earlier spectra were reanalyzed and evidence was found for the presence of two conformers, as suggested by previous ab initio investigations. The vibrational properties of the SiH bonds were explored by extending the ab initio calculations to a series of nonequilibrium structures, with the object of mapping variations in the SiH bond with change in torsional angle. This bond is strongest in the skeletal plane and weakest at right angles to the latter, which is in accordance with an n(N)−σ*(Si−H) orbital interaction. However the orientation of the other silyl group also influences SiH bond strength. Long-range interactions are found between the stretching motions of both SiH and SiCl bonds. The former appear to arise from dipole−dipole interactions between the SiH bonds, but the source of the latter remains obscure. The form of the observed νSiH spectrum suggests that signal averaging conceals the splittings expected from both interactions and bond strength variation. Electrical properties of the SiH and SiCl bonds are examined.

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Section: Resultscontrasting

confidence: 68%

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Fleischer

McKean

1999

J. Phys. Chem. A

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“…Initially, blank experiments were conducted with hydrocarbons and bases, and the resulting spectra were in excellent agreement with literature spectra. − In addition, since small changes from parent to complex were anticipated, blank experiments were performed whenever a new sample was prepared. This ensured a precise comparison between parent and complex spectra for every concentration of reactants studied.…”

Section: Resultsmentioning

confidence: 59%

Matrix Isolation Infrared and ab Initio Study of the 1:1 Complexes of Bromocyclopropane with NH₃ and (CH₃)₃N: Evidence for a Novel C−H···N Hydrogen Bond

et al. 1999

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Hydrogen-bonded complexes of bromocyclopropane with the strong bases ammonia and trimethylamine have been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the proton adjacent to the Br substituent on the cyclopropane ring to the nitrogen of the base was evidenced by distinct blue shifts of the C−H(Br) bending modes in the infrared spectrum. These shifts (∼12 cm-1 for the in-plane bend and ∼6 cm-1 for the out-of-plane bend) are much smaller than those observed for alkenes and alkynes, suggesting a distinct but extremely weak interaction. Ab initio calculations yield an essentially linear BrC−H···NH3 hydrogen bond with a C−H···N distance of 2.301 Å and a hydrogen bond energy of 2.35 kcal/mol, thus supporting that this hydrogen bond is one of the weakest observed thus far in a matrix. This study represents the first example of a (substituted) cyclopropane acting as a proton donor and only the second example of an alkane taking part in a C−H···N hydrogen bond.

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“…16 The assignments for these peaks, summarized in Table 1, are based on infrared data obtained on TMA in solid and gaseous states. 28,29 The loss peak at 383 cm 1 is in the frequency range characteristic of surface phonons; however, the surface is 'invisible' to the HREELS beam due to the presence of TMA (chemisorbed and physisorbed). Although this peak has been attributed to an N-C deformation mode, it is also possible that this loss is due to a frustrated translation or rotation of the physisorbed TMA molecules.…”

Section: Condensed Tmamentioning

confidence: 98%

“…1(a). Mass 59 is representative of desorption of the parent molecule, with other fragments also detected (28,42,58) as TMA breaks up in the quadrupole mass spectrometer. Masses 2 and 15 correspond to molecular hydrogen and CH 3 , respectively.…”

Section: Condensed Tmamentioning

confidence: 99%

HREELS, TPD and ESD study of electron‐induced decomposition of trimethylamine on Si(100) at 100 K

Lozano¹,

Early²,

Craig³

et al. 2005

Surface & Interface Analysis

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The effects of 600 eV electron irradiation on adsorbed layers of trimethylamine (TMA) on a Si(100) surface at 100 K were studied using high-resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), electron-stimulated desorption (ESD) and x-ray photoelectron spectroscopy (XPS). Experiments were performed at monolayer and higher coverages. The ESD results obtained on physisorbed TMA indicate electron-induced decomposition of the parent molecule. The HREELS data also show cleavage of N-C bonds on the chemisorbed layer of TMA and deposition of CH x groups on the surface, which is also supported by a dramatic enhancement of hydrogen desorption at 960 K following electron irradiation. This multiple-step process is supported by ESD signal decay curves obtained during electron irradiation. Following electron irradiation of TMA/Si(100), the intensity of low temperature TPD peaks corresponding to TMA fragments decreases; however, the intensity of the mass 2 peak increases dramatically compared with the un-irradiated surface. This is indicative of electron-induced associative desorption of molecular hydrogen. The HREELS data from monolayer coverage of TMA on Si(100) after electron irradiation suggests the removal of CH x groups from the adsorbate layer and deposition of carbon and hydrogen on the surface. In the absence of physisorbed layers there is no indication of electron-induced desorption of TMA fragments.

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Infrared Spectra of Solid and Matrix-Isolated (CH3)3N, (CD3)3N, and (SiH3)3N

Cited by 52 publications

References 14 publications

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Matrix Isolation Infrared and ab Initio Study of the 1:1 Complexes of Bromocyclopropane with NH₃ and (CH₃)₃N: Evidence for a Novel C−H···N Hydrogen Bond

HREELS, TPD and ESD study of electron‐induced decomposition of trimethylamine on Si(100) at 100 K

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Infrared Spectra of Solid and Matrix-Isolated (CH3)3N, (CD3)3N, and (SiH3)3N

Cited by 52 publications

References 14 publications

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Ab Initio Studies of Disilazanes: Structures and Vibrational Properties of Hexachloro-, Hexamethyl-, and Tetrachlorodisilazane

Matrix Isolation Infrared and ab Initio Study of the 1:1 Complexes of Bromocyclopropane with NH3 and (CH3)3N: Evidence for a Novel C−H···N Hydrogen Bond

HREELS, TPD and ESD study of electron‐induced decomposition of trimethylamine on Si(100) at 100 K

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Matrix Isolation Infrared and ab Initio Study of the 1:1 Complexes of Bromocyclopropane with NH₃ and (CH₃)₃N: Evidence for a Novel C−H···N Hydrogen Bond