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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 14 (1980), S. 8-13 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 13C NMR studies have been carried out on a series of organophosphorus compounds possessing P—N bonds. For the first time a one-bond temperature-dependent 13C - 31P nuclear spin coupling was observed for the P-phenyl carbons in bis(N,N-dibenzylamino)phenylphosphine (0-9 Hz) and bis(N,N-diethylamino)phenylphosphine (0-2 Hz). This temperature-dependent behavior can be rationalized in terms of free rotation about the phenyl phosphorus bond with concomitant hindered rotation about the P—N bonds. A conformational preference for the nitrogen and phosphorus lone pairs to exist in the trans orientation is indicated. In the similarly substituted 5-membered heterocyclic ring compound, 1,3-dimethyl-2-phenyl-1,3-diazaphospholidine, the phenyl one-bond coupling increases to (-) 42.1 Hz and becomes temperature independent. These data suggest that 1J(PC) is very responsive to electronic effects.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 13C NMR studies have been carried out on a series of phospholes and dibenzophospholes. The systems were analyzed with respect to ring conformation and substituent orientation. Assignments of all chemical shifts have been made by investigating partially relaxed inversion-recovery spectra and by investigating the field dependence of the spectra. A nonplanar (6-membered central ring) tricyclic phosphine was also examined. Here, the value of the two bond coupling constant 2J(PC) allowed determination of the orientation (axial) of the phosphorus-substituted phenyl ring. Conclusions regarding cyclic conjugation in phospholes are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0749-1581
    Keywords: 13C NMR ; 15N NMR ; Sodium tetrazolates ; tetrazoles ; bitetrazoles ; cobalt(III)tetrazole complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 13C and 15N nuclear magnetic resonance studies have been carried out on a series of sodium tetrazolate salts, 1,5- and 2,5-disubstituted tetrazoles, bitetrazoles, and cobalt(III) tetrazolate complexes of the type (PBu3n)Co(DH)2(5-R-tetrazolate), where DH is the monoanion of dimethylglyoxime. The 15N chemical shifts have been analysed with respect to structure, substituent effects, electron density as determined by molecular orbital calculations, Brønsted acidity, Lewis basicity and nucleophilicity of the nitrogen atoms in the ambidentate tetrazoles.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0749-1581
    Keywords: 1H and 13C NMR ; Phenyldibenzophospholes ; assignment, computer simulation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton and 13C NMR parameters have been determined for phenyldibenzophosphole and its oxide, sulfide, selenide and W(CO)5 complex from high-resolution one- and two-dimensional (COSY, HETCOR and 2DJ) experiments at 4.7, 7.1 and 9.4 tesla. Assignments of chemical shifts and coupling constants have been made and verified by computer simulation of the proton spectra. The data are discussed in relation to the geometry and electron density at phosphorus and the diamagnetic anisotropy of the W(CO)5 group.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0749-1581
    Keywords: Solid-state and solution structures; (R3P)2CdX2, (Et3P)2Cd2X4 and (Bu3P)3Cd2X4 Complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cadmíum (II) phosphine complexes (Et3P)2Cd2X4, (R3P)2CdX2 [R3P = Ph3,P, Bu3P, Et3P, 1-phenyldibenzophosphole (DBP), and 1-phenyl-3,4,-dimethylphosphole (DMPP)] and (Bu3P)3Cd2X4 (X = Cl, Br, I) have been prepared and their solution and solid state structures determined by a combination of elemental analyses, conductance, infrared and NMR spectroscopy. The structures of (Ph3P)2CdI2 (1) and (DBP)2CdI2 (2) have been determined from three-dimensional X-ray data collected by counter methods. Compound 1 crystallized in space group P21,/a with a = 18.312 (9), b = 10.285 (5), c = 19.311 (9) Å, β = 115.53 (4)° and Z = 4. Compound 2 crystallized in space group P21,/n with a = 12.698 (3), b = 15.302 (4), c = 17.477 (4) Å, β = 96.66 (2)° and Z = 4. The structures were refined by least-squares methods with RF = 0.041 and 0.048 for 4157 and 3393 unique reflections with I/σ(I) ≥ 2.0 for 1 and 2, respectively. Both molecules deviate from ideal C2v symmetry and have very slightly different Cd-I (1; 2.724 (2), 2.731 (2); 2; 2.718 (1), 2.721 (1) Å) and Cd-P (1, 2.631 (2), 2.653 (2); 2; 2.616 (3), 2.603 (3) Å) bond distances. The Cd-P bond distance differences are sufficient to give rise to a second order ABX CP/MAS 31P{1H} NMR spectrum for 1 but for 2 the phosphorus nuclei of the two DBP ligands are chemical shift equivalent. The CP/MAS 113Cd{1H} NMR spectra of both compounds 1 and 2 show apparent first order triplets. The (Bu3P)3Cd2X4 complexes are shown by variable temperature 31P{1H} NMR and conductance measurements to exist in solution as equilibrium mixtures of (Bu3P)2Cd2X4 and (Bu3P)2CdX2. CP/MAS 31P{1H} and 113Cd{1H} NMR spectra suggest that these compounds exist as doubly halide bridged (R3P)2Cd(μ-X)2CdX2(R3P) species containing four- and five-coordinate cadmium in the solid state. Equilibrium and activation thermodynamics for the ligand exchange processes of representative complexes have been determined from variable temperature 31P{1H} NMR spectra in CDCl3/CH2Cl2 (1:1) solutions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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