Molecular moments

Molecular moments of inertia are about 10 g/cm thus 7 values for benzene, N2, and NH3 are 18, 1.4, and 0.28, respectively, in those units. For the case of benzene gas, a = 6 and n = 3, and 5rot is about 21 cal K mol at 25°C. On adsorption, all of this entropy would be lost if the benzene were unable to rotate, and part of it if, say, rotation about only one axis were possible (as might be the situation if the benzene was subject only to the constraint of lying flat... 

Buckingham A D 1967 Permanent and induced molecular moments and long-range intermolecular forces Adv. Chem. Phys. 12 107... 

The rotational states are characterized by a quantum number J = 0, 1, 2,. .. are degenerate with degeneracy (2J + 1) and have energy t r = ) where 1 is the molecular moment of inertia. Thus... 

Each atom of a molecule that rotates about an axis through its centre of mass, describes a circular orbit. The total rotational energy must therefore be a function of the molecular moment of inertia about the rotation axis and the angular momentum. The energy calculation for a complex molecule is of the same type as the calculation for a single particle moving at constant (zero) potential on a ring. 

Rotational relaxation must depend to some extent on the molecular moment of inertia. 

Silverman, B. D. and Platt, D. E. (1996) Comparative molecular moment analysis (CoMMA) 3D-QSAR without molecular superposition. J. Med. Chem. 39, 2129-2140. 

Molecular Moments, Permanent and Induced, and Long-range Inter-... 

A. D. Buckingham. Permanent and induced molecular moments and long-range interactions. In I. Prigogine and S. A. Rice, eds., Adv. Chem. Phys. 12, p. 107, Wiley, New York, 1967. 

P. A. Madden. Workshop report The interference of induced and allowed molecular moments in liquids. In [45], p. 695. 

The next step is to connect the macroscopic susceptibility to individual molecular moments and finally to the number of unpaired electrons. From classical theory, the corrected or paramagnetic molar susceptibility is related to the permanent paramagnetic moment of a molecule, y. by ... 

Arsenious oxide is not a very polar substance chemically, and it would be expected to have a rather small molecular moment. That this is so was shown by Clark,11 who found the electrostatic moment to be 1-3 x 10 19 electrostatic units. This value was not affected by varying... 

A more refined description of dipole moments would also have to consider that lone pairs may also contribute to the molecular moment. This becomes important when the lone pairs are in directed nonspherical orbitals. In such cases, the center of negative charge in the electron cloud and the center of positive charge, the nucleus, do not coincide. The result... 

Inspection of the two sets of chair structures reveals that in one compound the all-equatorial conformer is overwhelmingly favored. In the other compound both chair structures have comparable energies so both will be populated significantly. In the all-equatorial isomer, the carbon-chlorine bond dipole moments reinforce one another leading to a large molecular moment. In the other compound the chlorines are both equatorial part of the time but part of the time they are trans diaxial where the carbon-chlorine bond dipole moments tend to cancel one another. Thus the average dipole moment of these two conformations will be less than the first compound, which exists virtually completely in the all-equatorial conformer. 

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