Knowledge Bank

The infrared spectra of the anhydrous metallocyanic acids $H4M(CN)6$ and $D4M(CN)6(M=Fe,Ru$ and Os) were measured in the solid state from $10,000-300cm-1$ at room temperature and at $80\circ K$. The results indicate that these compounds consist of $H4M(CN)6$ units, with the trans arrangement of the hydrogen atoms, which are linked together by asymmetrical N-H---N hydrogen bonds into a three dimensional network. All four hydrogen atoms per $H4M(CN)6$ unit are involved in hydrogen bonding, but two of them are more strongly hydrogen bonded than the other two. There is evidence that the stronger hydrogen bonds are nonlinear. Assignments are given for most of the bands in the spectra.