Knowledge Bank

The vibrational predissociation spectra of $Na+$ ($CH3OH)m((CH3)2CO)n$ (m + n $>$ 1; m, n $\ge$ 1), recorded between 3250 - $3800cm-1$, will be discussed and compared with clusters, $Na+$ ($CH3OH)m$, that do not contain any acetone molecules (n=0). Acetone is not infrared active in this spectral region, but is capable of participating in strong hydrogen bonds with methanol. Any change in the spectra between $Na+(CH3OH)m$ and $Na+(CH3OH)m((CH3)2CO)n$ can be attributed to the influence of one or more acetone molecules. As in the case of $Na+(CH3OH)m$ clusters, the smaller cluster sizes show an absorption around $3670cm-1$, which is attributed to mathanols with ‘free’ O-H groups. Methanols acting as proton donors to other acetone or methanol molecules absorb below $3500cm-1$. The structural impact due to the presence of one or more acetones will be discussed.