Calcul de constantes physiques moléculaires

Bernard-Moulin, Patrick; Pouzard, Guy

doi:10.1051/jcp/1979760708

Cited by 10 publications

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“…For example, the chemical shifts of both OPF 3 (−36 ppm) and OPCl 3 (2 ppm) lie upfield from the shifts of the unoxidized PF 3 (97 ppm) and PCl 3 (219 ppm). The oxidized shift change upon oxidation of PF 3 to OPF 3 has been calculated and is in good agreement with the experimental measurement.…”

Section: Resultssupporting

confidence: 77%

Chemistry of Diazaphospholephosphines. 2. Exocyclic Phosphine−Sulfido, −Selenido, and −Imido Derivatives of a Diazaphospholephosphine System. Crystal and Molecular Structures of Two Diazaphospholephosphine Imines: 4-(Difluoro((p-cyanotetrafluorophenyl)imino)phosphorano)-2,5-dimethyl-2H-1,2,3σ²-diazaphosphole and 4-(Bis(dimethylamino)(((pentamethylcyclopentadienyl)dichlorotitanio)imino)phosphorano)-2,5-dimethyl-2H-1,2,3σ²-diazaphosphole

1999

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The substituted-exo-phosphine (X = F, NMe(2), OCH(2)CF(3)) diazaphospholephosphines are exclusively oxidized at this center with either chalcogens (S, Se) or azides to phosphoranodiazaphospholes. Oxidation imparts a dramatic upfield shift of the phosphorus NMR signals and an increase in the (1)J(PC) coupling constants within the ring. (Difluorophosphino)diazaphosphole was also oxidized with selected amines using diethyl azodicarboxylate (DAD) as the coupling agent. Bulky amines (e.g., 2,4,6-tri-tert-butylaniline (mes)) gave the monomeric iminophosphorane whereas less bulky amines (p-toluidine) formed mostly the cyclic diazadiphosphetidine. The crystal and molecular structure of 4-(difluoro((p-cyanotetrafluorophenyl)imino)phosphorano)-2,5-dimethyl-2H-1,2,3sigma(2)-diazaphosphole was determined: triclinic, P&onemacr; (No. 2), a = 7.2744(15) Å, b = 10.087(4) Å, c = 10.566(2) Å, alpha = 66.62(2) degrees, beta = 77.60(2) degrees, gamma = 78.14(3) degrees, V = 688.8(4) Å(3), Z = 2. Final indices are R(1) = 0.0368 and wR(2) = 0.0968, and for all data, R(1) = 0.0478, wR(2) = 0.1033, and GOF = 1.067. The structure revealed two planar ring systems consisting of the diazaphosphole and the p-tetrafluorophenyl (tfbn) ring with an angle of 26.3 degrees between the rings. The angle about the phosphine imine nitrogen (i.e., P=N-tfbn) is relatively open (141.2(2) degrees ), and the P=N bond length is relatively short (1.514(2) Å). (((Trimethylsilyl)imino)(bis(dimethylamino))phosphorano)diazaphosphole gave, with CpTiCl(3), [(eta(5)-C(5)Me(5))TiCl(2)(N=P(NMe(2))(2)(2,5-dimethyl-2H-1,2,3sigma(2)-diazaphosphol-4-yl))], which was also characterized structurally: monoclinic, P2(1) (No. 4), a = 11.9477(11) Å, b = 8.4757(6) Å, c = 12.7567(11) Å, beta = 108.824(8) degrees, V = 1222.7(2) Å(3), Z = 2. Final indices are R(1) = 0.0630 and wR(2) = 0.1593, and for all data, R(1) = 0.0768, wR(2) = 0.1973, and GOF = 1.081. The Ti-N-P angle of 161.0(5) degrees was large, and the P=N distance (1.592(6) Å) and the Ti-N distance (1.781(6) Å) were both slightly shorter than those in similar titanium complexes. The P-N single bond distances between the exo-phosphorus atom and the attached dimethylamino groups were also short (1.649 Å (average)). These short values suggest delocalized bonding character throughout the metal-ligand framework, possibly a consequence of additional conjugation through the diazaphosphole ring.

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Section: Resultssupporting

confidence: 77%

Chemistry of Diazaphospholephosphines. 2. Exocyclic Phosphine−Sulfido, −Selenido, and −Imido Derivatives of a Diazaphospholephosphine System. Crystal and Molecular Structures of Two Diazaphospholephosphine Imines: 4-(Difluoro((p-cyanotetrafluorophenyl)imino)phosphorano)-2,5-dimethyl-2H-1,2,3σ²-diazaphosphole and 4-(Bis(dimethylamino)(((pentamethylcyclopentadienyl)dichlorotitanio)imino)phosphorano)-2,5-dimethyl-2H-1,2,3σ²-diazaphosphole

1999

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“…The average, isotropic chemical shielding ffiso (which would be comparable to the solution chemical shift) is given by the trace of the shielding tensor or °iso = V 3(<rn + tr22 + Ogg) (2) and the anisotropy A<7 is given by Act = phorus compounds. [62][63][64][65][66][67] In one theoretical approach, Letcher and Van Wazer,62'63 using approximate quantum-mechanical calculations, indicated that electronegativity effects, bond angle changes, and ir-electron overlap differences can all potentially contribute to 31P shifts in a number of classes of phosphorus compounds.…”

Section: Phosphorus-31 Chemical Shifts 1 Introduction and Basic Princ...mentioning

confidence: 99%

Conformation and Dynamics of DNA and Protein-DNA Complexes by 31P NMR

Gorenstein¹

1994

Chem. Rev.

215

231

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Contents 1. Introduction 1315 2. Phosphorus-31 Chemical Shifts 1316 1. Introduction and Basic Principles 1316 2. Theoretical 31P Chemical Shift Calculations 1316 and Empirical Observations 3. Bond Angle Effects 1317 4. Stereoelectronic Effects on 31P Chemical 1318 Shifts 5. Extrinsic and Other Effects on 31P 1318 Chemical Shifts 3. Assignment of 31P Signals of Oligonucleotides 1318 4. 31P Heteronuclear Coupling Constants 1319 5. 31P Melting Curves 1322 6. 31P NMR of Polynucleic Acids 1322 7. 31P NMR of DNA-Drug Complexes 1322 8. Sequence-Specific Variation in 31P Chemical 1323 Shifts and Coupling Constants of Duplex Oligonucleotides 1. 31P Chemical Shifts as a Function of 1324 Sequence and Position 2. Conformation and Dynamics of the 1325 Phosphate Ester Backbone 3. Origin of Sequence-Specific Variation in 1326 the « and f Torsional Angles and P-H3' Coupling Constants; C4'-C4' Interresidue Distances 4. 31P NMR Spectra of a Tandem 1328 GA-Mismatch Duplex, d(CCAAGATTGG)2 5. Comparison of the Phosphate Backbone

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Alkylthiophenes and their Reactions

Cagniant¹,

Cagniant²,

Paquer³

et al. 1986

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Calcul de constantes physiques moléculaires

Cited by 10 publications

References 0 publications

Conformation and Dynamics of DNA and Protein-DNA Complexes by 31P NMR

Alkylthiophenes and their Reactions

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