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2 Bulletin of the Polish Academy of Sciences. Chemistry

2 2000

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Physical image vs. structure relation, 5 [1]. Multinuclear NMR structural study on some hydrazones of O,O-Dialkyl 1-Oxoalkanephosphonates

Nazarski R. B., Gralak D. K., Kudzin Z. H.

Bulletin of the Polish Academy of Sciences. Chemistry

2000

Vol. 48, No. 1

27-33

An unambiguous method for determination of the configuration of any single 0,0-dialkyl 1-oxoalkanephosphonate hydrazones based on H, C, P NMR data has been elaborated; the use of 1 JCp (P-C=N) couplings is the most fruitful. The 12C/13C isotope effects on the P chemical shifts of selected compounds have been measured. For primary hydrazones the E/Z isomerisation with stabilisation of their Z forms through an intramolecular H-bonding has been proven. In addition, for the latter stereoisomers small scalar couplings between H-bonded groups N-H.. .O=P have been found, JHP 2.4-3.4 Hz. The possibility of the across H-bridge transfer of spin-spin interactions in these forms is also discussed.

Physical image vs. structure relation, 4[1]. Configuration and conformation determination of some bicyclic lactams by 1H NMR and theoretical methods

Nazarski R. B., Leśniak S.

Bulletin of the Polish Academy of Sciences. Chemistry

2000

Vol. 48, No. 1

17-25

Resolution-enhanced H NMR spectra of six single diastereomers of fused-ring sulfur-containing lactams have been recorded and interpreted. In joint analysis of derived couplings Ť/HH> performed with use of the Karplus-Conroy type relationship and results of static MM calculations, it was possible to determine the configuration of title compounds and the conformation elucidation of their six-membered rings. Simultaneously, the stereochemistry of the observed ring-closure reaction was determined. The application of TNDO/2 method for the prediction of n JHH values is also briefly discussed.