Neutral alkoxysilanes from silica gel and N-phenyldiethanolamine

Salazar-Hernández, Mercedes; Leyva‐Ramírez, Marco A.; Gutiérrez, J.A.

doi:10.1016/j.poly.2009.09.008

Cited by 6 publications

(3 citation statements)

References 35 publications

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“…It appears that the greater basicity of the trialkylamine donor in the diethanolamine ligand is counterbalanced by torsional strain suffered in the boat–boat conformation of the saturated dioxasilocane ring needed for strong nitrogen-to-silicon donation. Indeed, attenuation of the nitrogen basicity, as in N -aryldiethanolamines, results in adoption of a crown–crown conformation and scission of the Si–N interaction, with d (Si–N) > 3.0 Å. , …”

Section: Resultsmentioning

confidence: 99%

“…Indeed, attenuation of the nitrogen basicity, as in N-aryldiethanolamines, results in adoption of a crown−crown conformation and scission of the Si−N interaction, with d(Si−N) > 3.0 Å. 40,42 In compounds Cl(R)Si(ON[Me]O), the chlorine is apical in the crystallographically characterized product. This is in agreement with the well-known preference for more electronegative groups to preferentially adopt the apical positions in trigonal-bipyramidal compounds of the main-group elements due to the greater ionic character of the apical bonds.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Migrations of Alkyl and Aryl Groups from Silicon to Nitrogen in Silylated Aryloxyiminoquinones

Shekar

Brown

2013

Organometallics

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Silylation of the oxidized ligand in lead(II) bis(3,5-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-hydroxy-1phenyl)imine), Pb(ONO Q ) 2 , with chlorosilanes RSiX 2 Cl (R = Me, Ph; X = Me, Ph, Cl) results in the tetracyclic, pentacoordinate silicon compounds (ON[R]O)SiX 2 with a reduced, dianionic amine-bisphenolate ligand in which the methyl or phenyl group has migrated to nitrogen. Methyl migration is observed exclusively over phenyl migration, though phenyl migration is observed if no alkyl groups are present on silicon. Chlorotriphenylstannane reacts similarly, with migration of the phenyl group from tin to nitrogen. The five-coordinate products adopt a trigonalbipyramidal geometry with long bonds to the apical amine donors (d(Si−N) = 2.3−2.9 Å). Chlorine occupies the other axial position in strong preference to methyl or phenyl, while methyl has a modest preference for the axial position in comparison to phenyl (8.7:1).

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Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Migrations of Alkyl and Aryl Groups from Silicon to Nitrogen in Silylated Aryloxyiminoquinones

Shekar

Brown

2013

Organometallics

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“…In contrast to silatranes, the noncoordinating exo -form of silocanes is favored in most cases over the endo -form ( Scheme 1 ) [ 3 , 4 , 14 , 15 ]. The reasons for this can be either steric (f.i., no structurally characterized N-Ph silocanes [ 16 , 17 , 18 , 19 , 20 ] with pronounced N→Si interaction are known, whereas a fair number of exo N-Me silocanes [ 6 , 20 , 21 , 22 , 23 , 24 ] are known) or electronic (at least one additional electronegative substituent seems to be required on the silocane Si to exhibit enough electrophilicity for a stable N→Si interaction).…”

Section: Resultsmentioning

confidence: 99%

Oligosilanylated Silocanes

et al. 2021

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A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl, 1,1-bis[tris(trimethylsilyl)silyl], and 1,1-bis[tris(trimethylsilyl)germyl] substitution pattern as well as two examples where the silocane silicon atom is part of a cyclosilane or oxacyclosilane ring. The mono-tris(trimethylsilyl)silylated compound could be converted to the respective silocanylbis(trimethylsilyl)silanides by reaction with KOtBu and in similar reactions the cyclosilanes were transformed to oligosilane-1,3-diides. However, the reaction of the 1,1-bis[tris(trimethylsilyl)silylated] silocane with two equivalents of KOtBu leads to the replacement of one tris(trimethylsilyl)silyl unit with a tert-butoxy substituent followed by silanide formation via KOtBu attack at one of the SiMe3 units of remaining tris(trimethylsilyl)silyl group. For none of the silylated silocanes, signs of hypercoordinative interaction between the nitrogen and silicon silocane atoms were detected either in the solid state. by single crystal XRD analysis, nor in solution by 29Si-NMR spectroscopy. This was further confirmed by cyclic voltammetry and a DFT study, which demonstrated that the N-Si distance in silocanes is not only dependent on the energy of a potential N-Si interaction, but also on steric factors and through-space interactions of the neighboring groups at Si and N, imposing the orientation of the pz(N) orbital relative to the N-Si-X axis.

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