Coordinate vibration

Symmetry coordinates Vibrational quantum numbers FiJ V, k (varies) Fy = d V/dS,dSj... 

Appendix Normal Coordinates, Vibrational Wavefunctions, and Spectral Activities. 339... 

Fig. 5.15 Schematic representation of the normal modes of the Fe(ni)-azide complex with the largest iron composition factors. The individual displacements of the Fe nucleus are depicted by a blue arrow. All vibrations except for V4 are characterized by a significant involvement of bond stretching and bending coordinates (red arrows and archlines), hi such a case, the length of the arrows and archlines roughly indicate the relative amplitude of bond stretching and bending, respectively. Internal coordinates vibrating in antiphase are denoted by inward and outward arrows respectively (taken from [63])...

Point Imaginary frequency/cm l Relative amplitude of motion in reaction coordinate vibration (kyilkD)a Primary kHlkD... 

Complexes with type II structures are compiled in Table II along with their S—S distances and S—S vibrational frequencies. There are several examples of complexes of structure type Ila (planar trans end-on bridging coordination). Vibrational spectroscopy 174) indicates that this structure occurs in [(CN)5Co(S2)Co(CN)5] (7). Trans arrangement of the metal atoms has been proved by X-ray structure determination for [(NH3)5Ru(S2)Ru(NH3)5]Cl4 2H20 15, 44). 

Diborane. As shown in Table I, the B-H terminal stretching modes of diborane occur at an average frequency of 2563 cm-1, whereas the average of the bridging B-H stretches v% y6, 3, and vyi) occurs 28% lower, at 1847 cm-1. The existing normal coordinate vibrational analyses display some abnormalities, such as a near zero Hb-B-Hb bending force constant, but the general features of the force field for diborane are reasonably well understood. The vibrational analyses indicate that the B-Hb force constant is about half of that for B-Ht (i, 2,3). This... 

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