�ber Verbindungen der Siliciumtetrahalogenide mit aromatischen N-Heterocyclen: Best�tigung und Berichtigung

Wannagat, U.; Hensen, Karl; Petesch, P.

doi:10.1007/bf00909009

Cited by 9 publications

(3 citation statements)

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“…The enhanced reactivity of the complex, however, did not allow for slow crystallization and single-crystal X-ray diffraction analysis of this compound. As reported by Wannagat et al, HSiCl 3 (py) 2 decomposes upon treatment with polar solvents (under H vs Cl redistribution and the formation of H 2 SiCl 2 , SiCl 4 , and products thereof, as discussed below). In a more recent report, Fleischer et al described another example of such dismutation reactions: bis(dichlorosilyl)amine (in chloroform solution) reacts with substituted pyridines (Rpy) to yield H 3 SiCl, H 2 SiCl 2 , and HSiCl 3 .…”

Section: Introductionmentioning

confidence: 54%

Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines

et al. 2009

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Stable solid adducts of substituted pyridines (Rpy) with HSiCl(3) and HSiCl(2)Me were prepared in high yields under aprotic and anaerobic conditions at room temperature. The octahedral complexes of HSiCl(3) underwent dismutation reactions in polar solvents. In contrast, the HSiCl(2)Me(Rpy)(2) adducts were not susceptible to dismutation under comparable conditions, but they tended to dissociate more easily because of the reduced Lewis acidity of HSiCl(2)Me relative to HSiCl(3). The bonding between silicon and its surrounding ligands is highly ionic, as can be seen from QTAIM and charge distribution analyses. (29)Si CP/MAS spectra in combination with quantum-chemical calculations show that the lowest shielding is along the Cl-Si-Cl axis. The other two components of the shielding tensor are oriented along the N-Si-N and H-Si-Cl/Me axes. It is known that many reactions of (hydrido)chlorosilanes are catalyzed by pyridine bases. Therefore, the results presented here provide a basis for better control of these reactions, especially chlorine substitution and hydrosilylation.

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Section: Introductionmentioning

confidence: 54%

Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines

et al. 2009

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“…3)] was reduced with Cl3SiHpyridine by conditions given in the general method to yield 0.4 g (46%) of 38 as a light-yellow oil: NMR (CDC13) 0.85 (s, PCH3, 6 H), l. 20 (s, CCH3, 6 ), 2.40-2.90 (m, CH, 6 H); 13C NMR (CDC13) 4.8 (apparent t, X of AA'X, PCH3), 17.1 (s, CCH3), 41.7 (t, CH), 46.9 (t, CH), 48.8 (t, CH), 53.1 (s, CCH3); 31P NMR (CDC13) -1.8. The diphosphine was reacted in pentane with excess methyl iodide for 4 days at -18 °C.…”

Section: Methodsmentioning

confidence: 99%

“…This product was oxidized with 10% H202 to give 42: mp 153-154 °C. syfl-8-Methyl-8-phosphabicycIo[3.2.1]oct-6-ene 8-Oxide (44) and anti-8-Methyl-8-phosphabicyclo[3.2.1]oct-6-ene 8-Oxide (46). The procedure used was similar to that reported.30 To a brown bottle containing 0.…”

Section: Methodsmentioning

confidence: 99%

Bridged ring systems containing phosphorus: structural influences on the stereochemistry of silane reductions of P-oxides and on carbon-13 and phosphorus-31 NMR properties of phosphines

Quin¹,

Caster²,

Kisalus³

et al. 1984

J. Am. Chem. Soc.

103

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A number of bridged cyclic phosphine oxides, both saturated and unsaturated, have been reduced with silicon-based reagents. Evidence was obtained that pentacoordinate intermediates can have special importance in such reductions, since the contracted angle in the cycle is more compatible with the 90' angle offered by apical-equatorial bonding in the trigonal bipyramid. Thus, while HSiC13 and C6H5SiH3 reduce noncyclic oxides with stereochemical retention, phosphines with either retained or inverted configuration can result from angle-contracted, cyclic oxides, and in the 7-phosphanorbornene system (but not in higher homologues) the P(II1) intermediate can undergo retrocycloaddition, causing loss of the phosphorus bridge. However, when the pyridine complex of HSiC1, is used, these complications are avoided, apparently because of a change in mechanism. The bridged phosphines have been characterized by "C NMR spectroscopy, which is especially useful in revealing stereochemical features and modifications in the hybridization at phosphorus. Angle contraction in the ring diverts s-character into the exocyclic bond, causing extremely large lJpc values. Syn,anti isomers then appear to have different hybridization as judged by variations in their lJPc values. 31P NMR chemical shifts occur far downfield in 7-phosphanorbornenes, apparently as a result of U--T hyperconjugation; the anti isomer experiences a second effect, tentatively attributed to repulsion of the lone pair by interaction with the r-electrons, which superimposes shielding on 31P and causes their shifts to be significantly upfield of the syn isomers. The downfield shifting is weaker in 8-phosphabicyclo[3.2.l]octenes and absent in the [4.2.1] homologue. Saturated strained phosphines have shifts in the range of acyclic compounds. In two diphosphines, P-P coupling is present and its magnitude shown to be controlled by the orientation of the lone pair on phosphorus.The placement of phosphorus in heterocyclic frameworks can cause some important modifications in the properties associated with the particular phosphorus functionality.2 This is especially true when the creation of the cyclic structure requires strong contraction of the bond angles around the phosphorus atom, as in bridged ring systems. In working with tertiary phosphines and phosphine oxides containing this structural feature, we have encountered unique features in their reaction chemistry and NMR spectral properties. In this paper attention is focused on the stereochemical aspects of the highly important deoxygenation of phosphine oxides by silicon hydride^,^ which is generally the principal method by which phosphines with bridged rings are approached. While not a systematic study, our research has gathered enough information to show that serious departures from the mechanistic and stereochemical pathways established for simpler compounds can occur when phenylsilane and trichlorosilane are used as the reducing agents. Two configurations are usually possible for phosphines in bridged structures, and it ...

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Beiträge zur Chemie der Halogensilan‐Addukte, XI. Bis(1,10‐phenanthrolin)‐Komplexe des Siliciums. Darstellung, Struktur und Eigenschaften

Kummer¹,

Seshadri²

1977

Chem. Ber.

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�ber Verbindungen der Siliciumtetrahalogenide mit aromatischen N-Heterocyclen: Best�tigung und Berichtigung

Cited by 9 publications

References 0 publications

Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines

Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines

Bridged ring systems containing phosphorus: structural influences on the stereochemistry of silane reductions of P-oxides and on carbon-13 and phosphorus-31 NMR properties of phosphines

Beiträge zur Chemie der Halogensilan‐Addukte, XI. Bis(1,10‐phenanthrolin)‐Komplexe des Siliciums. Darstellung, Struktur und Eigenschaften

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�ber Verbindungen der Siliciumtetrahalogenide mit aromatischen N-Heterocyclen: Best�tigung und Berichtigung

Cited by 9 publications

References 0 publications

Octahedral HSiCl3 and HSiCl2Me Adducts with Pyridines

Octahedral HSiCl3 and HSiCl2Me Adducts with Pyridines

Bridged ring systems containing phosphorus: structural influences on the stereochemistry of silane reductions of P-oxides and on carbon-13 and phosphorus-31 NMR properties of phosphines

Beiträge zur Chemie der Halogensilan‐Addukte, XI. Bis(1,10‐phenanthrolin)‐Komplexe des Siliciums. Darstellung, Struktur und Eigenschaften

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Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines

Octahedral HSiCl₃ and HSiCl₂Me Adducts with Pyridines