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Investigation of Some Intramolecular Hydrogen Bonds by Nitrogen Magnetic Resonance Methods

100%

Stefaniak L.

1999

tom vol. 73 nr 1

173-180

It was shown that nitrogen NMR is a powerful tool in the studies of different types of hydrogen bridges (NHN)*, (NHN)-, (NHN), and (NHO). Some of the NMR parameters, originally proposed by us, provide information about charge redistribution and the extent of proton transfer. The character of hydrogen bonds depend upon solvent, temperature and the physical phase. The results of studies in the solid state using the 15N NMR CP MAS method were also discussed.

Investigations of intramolecular hydrogen bond by nitrogen magnetic resonance methods

63%

Schilf W. , Stefaniak L.

1998

tom Vol. 46, No. 1

15-33

Several examples of application of nitrogen NMR in investigation of intramolecular hydrogen bonds in nitrogen containing compounds have been presented. The exceptional properties of this method in quantitative estimation of physical parameters of hydrogen bridges have been confirmed.

Intermolecular (OHO)- hydrogen bond formed by a hydroxyquinoline derivative

51%

Wiench J. W. , Stefaniak L. , Grech E.

1999

tom Vol. 47, No. 1

67-75

(1)H, (13)C, (14)N, (15)N, (17)0, and (19)F NMR data are presented for HTFMQ and its complexes with DMAN in 2 .land 1 : 1 molar ratios. GIAO-CHF molecular orbital calculations for the [1H] and [4H] forms of the free molecule and its anion are also performed. The results show that the [4H] form of HTFMQ predominates in acetonitrile solutions. In both complexes with DMAN, HTFMQ forms a semi-anion containing an intermolecular hydrogen bond.

NMR spectroscopic investigations on molecular dynamics in the solid state

51%

Domalewski W. , Riddell F. G. , Stefaniak L.

1998

tom Vol. 46, No. 1

35-59

Representative examples of various large amplitude solid state dynamic phenomena are given. Several NMR techniques suitable for quantitative investigations of such processes are presented. The compability between X-ray diffraction and solid state NMR spectroscopy is pointed out. Common labile character of organic solids is discussed.

N NMR study of three proton sponges and some of their salts

45%

Klimkiewicz J. , Stefaniak L. , Grech E. , Brzeziński B. , Webb G. A.

1998

tom Vol. 46, No. 1

75-78

15N NMR data are reported for the three proton sponges DMAMN, DMAMB and DEAMB together with some of their salts with HNO3 and HC104. Low temperature 15N measurements on the monoperchlorate salts reveal the presence of a (N-H-N)+ structure from the values observed for 1J(15N-1H). The diperchlorate salts show monoprotonation of each nitrogen atom.