(CD3CN)2H+ adducts in anhydrous H3PW12O40: a FTIR study

The interaction of CD3CN with dehydrated H3PW12O40 in solid form has been studied by IR spectroscopy, and results are compared with those obtained for other CD3CN/acidic or CD3CN/superacidic solid systems (like zeolites in the acidic form and the perfluorosulfonic membrane H-NAFION). The formation of CD3CN . . .H+. . . NCCD3 adducts is demonstrated. These species are characterised by a characteristic band at 2330 cm(-1) and by a very broad absorption below 2000 cm(-1). On the basis of theoretical DFT ab initio calculations and by comparison with experimental results obtained on the analogous H5O2+ adducts, the above bands are assigned respectively to the nu (CN) and to the nu (N . . .H+. . .N) modes of the protonated (CD3CN)(2)H+ dimers.