29Si NMR chemical shifts of silane derivatives

Corminbœuf, Clémence; Heine, Thomas; Weber, Jacques

doi:10.1016/s0009-2614(02)00372-x

Cited by 36 publications

(30 citation statements)

References 30 publications

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“…Partial hydrolysis of the condensed volatile is also evident in the 29 Si NMR spectrum, and the two separate signals (d Si ¼ 19.4 and 23.3 ppm) are assigned to Me 3 Si-OH and Me 3 Si-Br (TMSP: d Si ¼ 6.1 ppm, CDCl 3 ). [18,19] The thermogravimetric analysis (TGA) in air has been carried out on phoH-PSU-34 and -38 to elucidate the influence of phosphonylation and ds P on decomposition temperature ( Figure 2). The TGA traces show a slight drift of À3.2 wt.-% up to T > 325 8C, as a result of water elimination during phosphonic acid anhydride formation.…”

Section: Resultsmentioning

confidence: 99%

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Bock

Mülhaupt

Möhwald

2006

Macromol. Rapid Commun.

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The nickel-catalyzed arylphosphonylation with tris(trimethylsilyl) phosphite (TMSP) is applied to brominated high-performance (HP) polymers in weakly coordinating high temperature solvents. At elevated temperatures, this affords halogen-free, soluble, phosphonic acid-functionalized polyelectrolytes and an unprecedented control of the degree of phosphonylation (ds P ). Brominated polysulfone (PSU) of various degrees of bromination (ds Br ) has been phosphonylated with TMSP in diphenyl ether at 200 8C in the presence of 1-10 mol-% NiCl 2 . Upon methanolysis, arylphosphonic PSU with ds P up to 223 mol-% is obtained in near quantitative bromine conversion. Catalyst residues are readily removed during methanolysis. This very versatile two-step process affords soluble arylphosphonic polymers for casting tough membrane films. In contrast to sulfonated PSU, the arylphosphonic PSU membranes exhibit improved thermal and chemical stabilities, combined with far lower water swelling in accordance with the demands of polyelectrolyte membrane fuel cell (PEMFC) applications.Mass swelling (sw M ) in water of sulfonated (A-C) and phosphonylated PSU (D).

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Section: Resultsmentioning

confidence: 99%

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Bock

Mülhaupt

Möhwald

2006

Macromol. Rapid Commun.

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“…A comparison between the calculated and experimental principal components shows a good accordance for d 22 , but significant deviations for d 33 and especially d 11 , the components which are nearly perpendicular to the Si À H bonds. It has been shown previously [20,21] that siliconbound hydrogen atoms cause inaccuracies in 29 Si NMR shift calculations, and this problem has not yet been solved theoretically.…”

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confidence: 99%

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Fester

Wagler

Brendler

et al. 2008

Chemistry A European J

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H(2)SiCl(2) and substituted pyridines (Rpy) form adducts of the type all-trans-SiH(2*)Cl(2)2 Rpy. Pyridines with substituents in the 4- (CH(3), C(2)H(5), H(2)C=CH, (CH(3))(3)C, (CH(3))(2)N) and 3-positions (Br) give the colourless solids 1 a-f. The reaction with pyrazine results in the first 1:2 adduct (2) of H(2)SiCl(2) with an electron-deficient heteroaromatic compound. Treatment of 1 d and 1 e with CHCl(3) yields the ionic complexes [SiH(2)(Rpy)(4)]Cl(2*)6 CHCl(3) (Rpy=4-methylpyridine (3 d) and 4-ethylpyridine (3 e)). All products are investigated by single-crystal X-ray diffraction and (29)Si CP/MAS NMR spectroscopy. The Si atoms are found to be situated on centres of symmetry (inversion, rotation), and the Si-N distances vary between 193.3 pm for 1 c (4-(dimethylamino)pyridine complex) and 197.3 pm for 2. Interestingly, the pyridine moieties are coplanar and nearly in an eclipsed position with respect to the SiH(2) units, except for the ethyl-substituted derivative 1 e, which shows a more staggered conformation in the solid state. Calculation of the energy profile for the rotation of one pyridine ring indicates two minima that are separated by only 1.2 kJ mol(-1) and a maximum barrier of 12.5 kJ mol(-1). The (29)Si NMR chemical shifts (delta(iso)) range from -145.2 to -152.2 ppm and correlate with the electron density at the Si atoms, in other words with the +I and +M effects of the substituents. Again, compound 1 e is an exception and shows the highest shielding. The bonding situation at the Si atoms and the (29)Si NMR tensor components are analysed by quantum chemical methods at the density functional theory level. The natural bond orbital analysis indicates polar covalent Si-H bonds and very polar Si-Cl bonds, with the highest bond polarisation being observed for the Si-N interaction, which must be considered a donor-acceptor interaction. An analysis of the topological properties of the electron distribution (AIM) suggests a Lewis structure, thereby supporting this bonding situation.

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“…In this article, we have tested on a benchmark set of 1 ( E ), 1 ( Z ) and 2 ( Z ) the reliability of three different functionals, namely, the most popular three‐parameter hybrid exchange‐correlation functional of Becke and Lee‐Yang‐Parr known worldwide as B3LYP together with the less common hybrid functional PBE and exchange‐correlation functional B1PW91 . The former is routinely used for almost all types of DFT calculations, also showing reasonably good results in the standard computations of NMR parameters,[] whereas the latter two functionals developed by Perdew, Adamo and coworkers [14,15,16,17] are more NMR‐oriented providing sufficiently accurate results for the calculation of NMR chemical shifts . Three standard basis sets were used in this study: double and triple zeta polarised sets (DZP and TZP) together with the triple zeta basis set augmented with an additional polarisation function, TZ2P .…”

Section: Resultsmentioning

confidence: 99%

The effects of intramolecular and intermolecular coordination on ³¹P nuclear shielding: phosphorylated azoles

Chernyshev

Ларина²,

Chirkina³

et al. 2012

Magnetic Reson in Chemistry

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The effects of intramolecular and intermolecular coordination on (31)P nuclear shielding have been investigated in the series of tetracoordinated, pentacoordinated and hexacoordinated N-vinylpyrazoles and intermolecular complexes of N-vinylimidazole and 1-allyl-3,5-dimethylpyrazole with phosphorous pentachloride both experimentally and theoretically. It was shown that either intramolecular or intermolecular coordination involving phosphorous results in a dramatic (31)P nuclear shielding amounting to approximately 150 ppm on changing the phosphorous coordination number by one. A major importance of solvent effects on (31)P nuclear shielding of intramolecular and intermolecular complexes involving N → P coordination bond has been demonstrated. It was found that the zeroth-order regular approximation-gauge-including atomic orbital-B1PW91/DZP method was sufficiently accurate for the calculation of (31)P NMR chemical shifts, provided relativistic corrections are taken into account, the latter being of crucial importance in the description of (31)P nuclear shielding.

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29Si NMR chemical shifts of silane derivatives

Abstract: Geometries

Cited by 36 publications

References 30 publications

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

The effects of intramolecular and intermolecular coordination on ³¹P nuclear shielding: phosphorylated azoles

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29Si NMR chemical shifts of silane derivatives

Abstract: Geometries

Cited by 36 publications

References 30 publications

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Halogen‐Free Polyarylphosphonates and Polyelectrolyte Membranes for PEMFC by Nickel‐Catalyzed Phosphonylation with Silylated Phosphates

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and 29Si NMR Chemical Shifts

The effects of intramolecular and intermolecular coordination on 31P nuclear shielding: phosphorylated azoles

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Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

The effects of intramolecular and intermolecular coordination on ³¹P nuclear shielding: phosphorylated azoles