Raman spectroscopic studies of polymorphic N2H7I. Phase transition, orientational disorder and hydrogen bonding

Lutz, H. D.; Alici, E.; Henning, J.; Berthold, H. J.; Vonholdt, Elke

doi:10.1016/0022-2860(90)80104-r

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…It forms several polymorphs in which the NH 4 + ion is connected with NH 3 adduct by a hydrogen bond, for which theoretical methods gave bond energies 116-130 kJ mol À1 . 21 In fact our results suggest that we have observed another solid containing the NH 4 + ÁNH 3 adduct as the cation and its formula may be proposed as (N 2 H 7 ) 4 SiW 12 O 40 . From the results obtained for irreversibly sorbed ammonia at 373 K (sample 1) and 298 K (sample 2) the enthalpy of N 2 H 7 + in the solid can be calculated.…”

Section: Discussionmentioning

confidence: 55%

Calorimetric study of ammonia sorption on H₄SiW₁₂O₄₀

Lalik

Micek‐Ilnicka

Groszek

et al. 2003

Phys. Chem. Chem. Phys.

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Section: Discussionmentioning

confidence: 55%

Calorimetric study of ammonia sorption on H₄SiW₁₂O₄₀

Lalik

Micek‐Ilnicka

Groszek

et al. 2003

Phys. Chem. Chem. Phys.

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Chelation of a Proton by an Aliphatic Tertiary Diamine

et al. 2008

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A series of monoprotonated aliphatic diamines has been examined, which crystallize in three general motifs: salt-bridged, cyclic, or clustered. The monoprotonated triflic acid salt of Me2N(CH2)4NMe2 forms a proton-bridged cyclic cation. The internal N-N distance is 2.66 A, with the bridging proton in the middle, having an NHN angle >/=172 degrees. The triflate oxygens lie more than 4 A away from the midpoint between the nitrogen atoms, indicating that a salt bridge does not form. The average NH distance in a solid sample was determined by measuring the 15N-H dipolar coupling in the triflic acid salt of the completely deuterated diamine (CD3)2N(CD2)4N(CD3)2. The value of the dipolar coupling constant, 5250 +/- 90 Hz, corresponds to an average NH distance of 1.32 A, nearly half-the NN distance. That result agrees with DFT calculations, which give a double-well potential minimum for proton transit between the two amino groups, having a zero-point vibrational level close to the barrier top. Theory predicts that the maximum value of the zero point vibrational wave function is almost coincident with a local potential energy maximum, consistent with the experimental findings.

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