Determination of the Molecular Structure of Dimethyl(silyl)amine, Dimethyl(methylsilyl)amine and Dimethyl(dimethylsilyl)amine in the Gas Phase by Electron Diffraction.

Gundersen, Grete; Mayo, Richard; Rankin, David W. H.; Westdahl, Marianne

doi:10.3891/acta.chem.scand.38a-0579

Cited by 29 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to alkylamines, which almost always have pyramidal nitrogen atoms, it is a generally accepted rule that silylated nitrogen compounds have planar coordination at the nitrogen atoms, and only a few exceptions have been found so far. , Compounds with slight deviation from planarity include R x Si(NH 2 ) 4 - x (crystal structures for x = 1−3, R = bulky aryl group), H 3 CH 2 SiNMe 2 , H 3 SiNMe 2 , and ClH 2 SiNMe 2 , all studied by gas-phase electron diffraction (GED). Moreover, the nitrogen coordination can be forced to be pyramidal by incorporation into a small ring cycle such as aziridine as a result of ring strain .…”

Section: Introductionmentioning

confidence: 99%

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

Mitzel

Oberhammer

1998

Inorg. Chem.

View full text Add to dashboard Cite

N,O-Dimethyl-N-silylhydroxylamine (H(3)SiMeNOMe) has been prepared by reaction of HMeNOMe with H(3)SiBr and 2,6-lutidine as an auxiliary base. Its identity has been proved by gas-phase IR and solution NMR spectroscopy of the nuclei (1)H, (13)C, (15)N, (17)O, and (29)Si and by mass spectrometry. The solution NMR data indicate aggregation of the compound in solution. H(3)SiMeNOMe decomposes within weeks at ambient temperature, and an extrusion of methylnitrene is probably the mechanistic pathway involved. The final products of this decomposition are an insoluble precipitate and SiH(4). The energy of H(3)SiMeNOMe relative to its potential rearrangement isomer MeHN-H(2)Si-OMe has been estimated by ab initio calculations to be 289 kJ mol(-)(1). The molecular structure of H(3)SiMeNOMe has been determined by gas-phase electron diffraction and by ab initio calculations. The results show H(3)SiMeNOMe to possess a steeply pyramidal nitrogen atom and to adopt a trans conformation. It is thus the first silyl nitrogen compound that adopts a typically pyramidal nitrogen coordination for purely electronic reasons. The Si-N bond is found to be only slightly elongated with respect to those of comparable compounds with planar nitrogen coordination. Important bond length and angles are Si-N 1.742(1), N-O 1.449(4), N-C 1.460(3), and O-C 1.425(4) Å and Si-N-C 121.8(5), Si-N-O 104.3(4), C-N-O 106.2(12), and N-O-C 103.2(12) degrees. Results of an NBO analysis show the silyl group to be bound by a nitrogen sp(2) hybrid, the d-orbital contribution at silicon to be less than 2%, and the N-O bond to comprise mainly p-orbital contribution. The presence of a marked p(lp-N)-sigma(Si-H) hyperconjugation in the NBO description shows that this effect cannot be solely responsible for the generally observed flattening of the nitrogen coordination in silylamines.

show abstract

Section: Introductionmentioning

confidence: 99%

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

Mitzel

Oberhammer

1998

Inorg. Chem.

View full text Add to dashboard Cite

show abstract

“…In the course of these studies, some singly silylated nitrogen compounds with slightly pyramidal nitrogen coordination have been found. These include the systems R x Si(NH 2 ) 4- x (crystal structures for x = 1−3, R = bulky aryl group 7 ) and (CH 3 )H 2 SiN(CH 3 ) 2 , H 3 SiN(CH 3 ) 2 , and ClH 2 SiN(CH 3 ) 2 , all studied by GED. Expansion of the coordination sphere of both the silicon and the nitrogen atoms has been observed in the crystal structures , of the last two of these.…”

Section: Introductionmentioning

confidence: 99%

The Pyramidal Si₂N−O Skeleton of O-Methyl-N,N-disilylhydroxylamine: An Inherent Phenomenon As Confirmed by Structural Studies in Different Phases

et al. 1996

Self Cite

View full text Add to dashboard Cite

O-Methyl-N,N-disilylhydroxylamine, (H3Si)2NOCH3 (1), has been prepared by the reaction of bromosilane with O-methylhydroxylamine in the presence of 2,6-lutidine. The compound has been found to be reasonably stable at ambient temperature, but explodes if heated to 200 °C. 1 has been completely characterized by MS, HRMS, IR in the solid state and gas phase, and NMR spectra of the nuclei 1H, 13C, 14/15N, 17O, and 29Si. The NMR chemical shifts are compared with those of Si-methylated derivatives and with values obtained in high-level ab initio calculations. It has been concluded that there is close similarity between the structure in solution and the calculated one. A single crystal of 1 grown in situ and studied by X-ray diffraction is orthorhombic, space group P212121, a = 6.3664(11) Å, b = 8.488(2) Å, c = 11.783(4) Å, ρcalc = 1.119 g cm-1, Z = 4. Intermolecular Si···O interactions (2.92 Å) are found in the solid state structure leading to a zigzag type aggregation of the molecules. The gas phase structure of 1 has been determined by electron diffraction showing the molecule to have C s symmetry. In both phases, the crystalline and the gas phase, the nitrogen atom configuration of 1 is pyramidal [∑<(N) GED 351.8(12)°, XRD 352.8(3)°], showing this to be an inherent feature of N-silylated hydroxylamines and not caused by packing forces. Most of the geometrical parameters are consistent for both phases showing that the intermolecular Si···O interactions cause only minor structure distortions. The structural results are discussed in comparison with ab initio calculated geometries, and it is concluded that the exceptional nitrogen configuration is caused by repulsion between the nitrogen and oxygen lone pairs of electrons.

show abstract

“…Both methods predict the Si-N and Si-C bonds to be too long (see Table 3). Because of ring strain the experimental Si-N bond (1.724(5) Å) in 1 is slightly longer than those in unstrained silyldimethylamine (1.713(5) Å) 22 or in bis(dimethylamino)silane (1.708(3) Å). 24 The Si-N bond length in 1 is, however, well within the range of Si-N bond lengths observed in gaseous silylamines (1.70-1.74 Å).…”

Section: Discussionmentioning

confidence: 83%

“…This low degree of puckering in 1 can be rationalized by increased angle strain in the ring system of 1 . The SiNC angle in unstrained silyldimethylamine (120.9(3)°) is considerably larger than the SiCC angle in unstrained 1-silabutane (113.0(6)°) . In the cyclic compound 1 the SiNC angle (112.6(8)° is also about 9° larger than the SiCC angle (103.6(3)°) in 3.…”

Section: Discussionmentioning

confidence: 87%

Molecular Structure and Conformations of 2,2-Di-tert-butyl-1,3-diaza-2-silacyclopentane: Gas Electron Diffraction and Quantum Chemical Calculations

et al. 2004

View full text Add to dashboard Cite

The geometric structure and conformational properties of the saturated five-membered-ring compound 2,2-di-tert-butyl-1,3-diaza-2-silacyclopentane, (t-Bu)(2)Si(NH)(2)(CH(2))(2), was investigated by gas electron diffraction and quantum chemical methods (B3LYP and MP2 with 6-31G basis sets). The compound exists as a mixture of two conformers, both possessing a twist conformation and C(2) symmetry. In the prevailing form (76(6) % at 305 K) the N-H bonds stagger the adjacent CH(2) groups, and in the minor form the N-H bonds eclipse the CH(2) groups. This conformational mixture corresponds to a free energy difference of DeltaG degrees = 0.69(19) kcal/mol. The B3LYP method predicts a preference for the eclipsed conformer. The largest torsion occurs around the C-C bond with tau(NCCN) = 29.2(24) degrees. The degree of puckering in the title compound is considerably smaller than that in silacyclopentane with tau(CCCC) = 49.7(14) degrees. This has been rationalized by larger angle strain in the title compound.

show abstract

Determination of the Molecular Structure of Dimethyl(silyl)amine, Dimethyl(methylsilyl)amine and Dimethyl(dimethylsilyl)amine in the Gas Phase by Electron Diffraction.

Cited by 29 publications

References 0 publications

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

The Pyramidal Si₂N−O Skeleton of O-Methyl-N,N-disilylhydroxylamine: An Inherent Phenomenon As Confirmed by Structural Studies in Different Phases

Molecular Structure and Conformations of 2,2-Di-tert-butyl-1,3-diaza-2-silacyclopentane: Gas Electron Diffraction and Quantum Chemical Calculations

Contact Info

Product

Resources

About

Determination of the Molecular Structure of Dimethyl(silyl)amine, Dimethyl(methylsilyl)amine and Dimethyl(dimethylsilyl)amine in the Gas Phase by Electron Diffraction.

Cited by 29 publications

References 0 publications

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

A Steeply Pyramidal Silylamine: N,O-Dimethyl-N-silylhydroxylamine

The Pyramidal Si2N−O Skeleton of O-Methyl-N,N-disilylhydroxylamine: An Inherent Phenomenon As Confirmed by Structural Studies in Different Phases

Molecular Structure and Conformations of 2,2-Di-tert-butyl-1,3-diaza-2-silacyclopentane: Gas Electron Diffraction and Quantum Chemical Calculations

Contact Info

Product

Resources

About

The Pyramidal Si₂N−O Skeleton of O-Methyl-N,N-disilylhydroxylamine: An Inherent Phenomenon As Confirmed by Structural Studies in Different Phases