Interactions rotational

Prior to this 1996 study, there had been no reports of boratabenzene complexes of early transition metals.42 An X-ray crystal structure of the catalyst revealed a C2-symmetric geometry that resembles Cp2Zr-based bent metallocenes. The bond lengths suggest a strong B-N it interaction (rotational barrier measured by NMR 18 kcal/mol) and a very weak Zr B interaction ( t 5 coordination of the boratabenzene ring). 

In this equation, the energies , and / of the initial and final states, i) and I/), and the dipole moment all refer to a pair of diatomic molecules hcvij = Ef — Ei is Bohr s frequency condition. With isotropic interaction, rotation and translation may be assumed to be independent so that the rotational and translational wavefuntions, population factors, etc., factorize. Furthermore, we express the position coordinates of the pair in terms of center-of-mass and relative coordinates as this was done in Chapter 5. 

In proteins, the position of the axial histidine ring determines the inequivalence of protons in the porphyrin plane. Probably as a result of this, a variety of patterns is observed with either one or two of the four methyl substituents of protoporphyrin IX being downfield [2,27,59-62]. The orientation of the Xx and Xy axes in the porphyrin plane depends on the orientation of the axial Tt interaction, with a behavior analogous to the low spin Fe(III) case, but with the x and y axes interchanged. In other words, when the Tt interaction is along a metal-pyrrole nitrogen direction, it defines the Xy and not the Xx direction. When the Tt interaction rotates... 

The NMR frequencies at two times separated by the time tm, and thus the corresponding orientations [cf. Eq. (15)] are correlated via cosine functions. The correlation function CSin(fm tp), where the cosine functions are replaced by sine functions, may also be accessible modifying pulse lengths and pulse phases in an appropriate way. This is possible for both CSA and Q interactions. Rotational jumps of the molecules during the mixing time tm lead to 0)>(0) / tm), and hence to a decay of CCOSjSin(fm tp). Therefore, these correlation functions provide access to the details of the molecular reorientation dynamics. 

If a pair of inert-gas atoms held together by the Lennard-Jones interaction rotates, the centrifugal force MRco will increase their separation. The maximum frequency of rotation will be at the separation R. such that the attractive force dV /dR divided by MR is maximum. Determine that frequency and the corresponding separation for neon, using experimental <7 and from Table 12-2. 

Peterson, K. I., and Klemperer, W., Water-hydrocarbon interactions Rotational. spectroscopy and structure of the water-acetylene complex, J. Chem. Phys. 81, 3842-3845 (1984). 

M. Mehring, Internal spin interactions rotations in solids, in Encyclopedia of Nuclear Magnetic Resonance, D.M. Grant and R.K. Harris, eds., Wiley, Chichester, 1996, 2585-2603. 

As usual, polarization-transfer experiments where the relevant quantization axis is the static magnetic field will be called laboratory-frame experiments, while experiments where the applied r.f. field provides the relevant quantization will be referred to as rotating-frame experiments. This classification should not be confused with the frame of reference where the Hamiltonian is set up and the equation of the motion is solved in. Usually, laboratory frame polarization-transfer experiments are described in a rotating (or doubly rotating in heteronuclear cases) frame of reference that is an interaction frame with respect to the dominant Zeeman interaction. Rotating-frame experiments are usually described in a frame of reference obtained by going into a further interaction representation, this time with respect to the r.f. field. 

Attack of the electrophile at one end of the helical diene would result in a zwitterion in which direct closure to a 3,6-dihydrothiazine oxide is blocked by a severe methyl-methyl group steric interaction. Rotation of the C-1—C-2 bond in the opposite direction requires only that the methine hydrogen pass the C-4 methyl group. This rotation also would... 

Linear Triatomic Molecules Anharmonic (Fermi) Interactions Rotational Spectroscopy Electromagnetic Transition Intensities... 

Having demonstrated the achievement of high-resolution sohd state NMR capability, the authors describe experiments that combine the high-resolution aspect of MAS NMR with methods that retain the structure and/or dynamic information inherent in the anisotropic interactions. Rotational-echo double resonance (REDOR) allows the determination of D between isolated heteronuclear spin pairs. D is related simply and without approximation to intemuclear separation. Hence, REDOR makes possible the unambiguous direct determination of intemuclear distance between the labeled spin pair, independent of pair orientation, i. e., in amorphous and /or microaystaUine solids, and extends our abihty to quantitatively explore complex materials. It is also possible to extract intemuclear distance from homonuclear dipolar coupled spin pairs, and these experiments are also reviewed. 

The strongest of these interactions between neutral molecules is the dipole-dipole interaction. Rotations in the gas phase average the dipole-dipole potential energy to the form... 

Fig. 2. Possible multimodal interactions using 2 mice for tow-handed interaction (rotating the satellite) and speech input...

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