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219 results on '"Ratcliffe, C. I."'

5. (6,17-dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]-tetra-aza[14]annulenato)nickel(II) in solids: two guest-free polymorphs and inclusion compounds with methylene chloride and fullerene (C (sub)60)-carbon disulfide

Author

Soldatov, D. V., Diamente, P. R., Ratcliffe, C. I., and Ripmeester, J. A.

Subjects
Chemistry, Inorganic -- Research, Nickel -- Physiological aspects, Solids -- Physiological aspects, Carbon allotropes -- Physiological aspects, Methylene chloride -- Physiological aspects, Carbon disulfide -- Physiological aspects, Nuclear magnetic resonance spectroscopy -- Usage, Chemistry
Abstract

Research has been conducted on the guest-free polymorphs and inclusion compounds. The isolation and characterization of these compounds have been carried out via the single-crystal and powder XDR, solid-state (super)13 C NMR and other methods and the results are reported.

Published
2001

6. A study of the molecular dynamics of compounds containing rotor groups of C₃ symmetry

Author

Ratcliffe, C. I.

Subjects
543
Abstract

Models for calculation of barriers to rotation from torsional mode frequencies were reviewed, and a new simple harmonic quantum mechanical treatment of two coaxial rotors with both internal and external barriers was developed. Torsional and librational mode frequencies of several sets of compounds containing hydrogenous rotor groups were obtained principally by incoherent inelastic neutron scattering, with reference to both new and old infrared and Raman studies. The internal and external potentials in the N(_2)H(_6)(^+2) halide salts were calculated using the new model. The external barriers were used to calculate the appreciable hydrogen bond strengths, and the internal barrier was found to be less than in ethane. The different phases of the monomethylammonium halide and PF(_6)(^-)salts were studied, including selective deuteration studies, and the new model again applied to obtain barriers. The model worked well for the chloride p-phase but began to break down for the bromide indicating loss of simple harmonic behaviour. The other phases all displayed non-harmonic behaviour. The internal barrier was found tobe intermediate between that of N(_2)H(_6)(^+2) and C(_2)H(_6). In the C(_6)H(_5)NH(_3)(^+)C1(^-) and Br(^-) salts the internal barrier was found to be very small, and the external -NH(_3)(^+) torsional barrier for the chloride was in good agreement with that in N(_2)H(_6)(^+2)C1(_2)(6-). A large number of methyl-halogeno compounds of the group IV elements were studied. Multiple top torsional mode frequency splittings were observed and their neutron scattering intensities related to their mode degeneracies. Several previous I.R. determinations were shown to be in error. The di-, tri- and tetra-methylammonium halide salts were studied and torsional mode splittings were again observed. Barriers to methyl rotation were found to be relatively high, and steric effects due to the short C-N bond length, and external influences, were found to be quite important.

Published
1975

18. A 1H and 2H nuclear magnetic resonance study of amorphous ices at 77 K.

Author

Ripmeester, J. A., Ratcliffe, C. I., and Klug, D. D.

Subjects
*HYDROGEN, *NUCLEAR magnetic resonance, *ICE
Abstract

The 2H quadrupole coupling constants (QCC) of deuteriated high-density amorphous (hda) ice and low-density amorphous (lda) ice were measured to be 226.6 and 218.6 kHz with asymmetry parameters (η) 0.106 and 0.104, respectively, at 77 K. Correlations of the QCC’s with near-neighbor O–O distances in the crystalline phases of ice imply near-neighbor O–O distances of 2.84 and 2.79 Å in high- and low-density amorphous ice, respectively, compared with values of 2.79 and 2.77 Å for cubic ice (Ic) and hexagonal ice (Ih). The 1H second moment for hda ice of 37.5 G2 can be understood in terms of a short water interproton distance of 1.565 Å and the greater density of hda ice with respect to ice Ih. The 1H spin-lattice relaxation times at 77 K for hda ice and lda ice at 124 and 773 s are much shorter than the value found for the crystalline ices. It is suggested that the T1 parameter may be useful in characterizing different amorphous ice phases. [ABSTRACT FROM AUTHOR]

Published
1992
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