Vibrational Spectrum and Structure of Single Crystals of K3Co(CN)6

The polarized infrared absorption spectra of single crystals of K3Co(CN)6 have been observed from 5000 to 280 cm—1. By combining this data with Raman and crystal structure data of other authors, most of the fundamental frequencies have been assigned. Force constants have been calculated using the recently derived resonance interaction valence force potential function which reduces the number of interaction terms in accord with theories of bonding. The primary stretching force constants are: FCN=16.8 md/A and FCoC=1.8 md/A.It is shown that the observed spectrum cannot be satisfactorily explained with a Urey‐Bradley force field.