1H and 31P solid-state NMR of trimethylphosphine adsorbed on heteropolytungstate supported on silica

Silica interacts with TMP by two kinds of acid sites: with weak acid support sites through the isolated silanol groups and with strong Brönsted acid, which lead to the formation of TMPH+, through the hydrogen-bonded silanol groups. Silica only interacts with HPW through its isolated silanol groups.