Riding-motion corrections

In this case, the riding motion effect due to the soft bending force constants and the anharmonicity effect due to the soft stretching force constants result in corrections which are significant in terms of the experimental standard deviations. These corrections are (fortunately) in opposite directions. At very low temperatures, 15 K, they tend to cancel, so that the difference is within the experimental errors, as shown in Thble 3.5. At room temperatures, the riding motion correction is predominant. 

Vibration corrected bond lengths based on the riding model for C(2)—N(1), rigid body libration for other C—N bonds, libration plus riding motion for N—H bonds. 

Table 3.5. Riding motion and anharmonicity corrections for C-H and N-H bond lengths in the neutron diffraction analyses at 15 K of deuterated benzene [203], thioacetamide [204], and 1,2,4-triazole [199]...

Estimated standard deviations are, for all values shown, 0.02 A for distances and 1° for angles. Atom related by center of symmetry at Vi. 0, Vi- ° Values in brackets are distances corrected for libration of AsF " assuming riding motion of each light atom on the heavier. 

Interatomic distances given within square brackets are distances corrected for the riding motion of the F atom on the Xe atom. The force constants were evaluated following Herzberg with X, + X3 = Mf( i + 2) + + 2 2 12) and XjXj = (ft , 2 - i2 )(Mf +... 

Complexes of Palladium(ll) and Platiniun(ll).—Non-chelate Complexes. Accurate redeterminations of the structures of potassium tetrachloro-platinate K2[PtCl4] and the analogous palladium complex confirm that the [MCU3 - anions are exactly square-planar. The mean Pd-Cl distance of 2.313(2) A is very slightly longer than the mean Pt-Cl distance of 2.308(2) A however, after correction for the effects of thermal motion, on the assumption that the chlorine atoms ride on the metal atoms, the values are equal... 

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