(A,B,C) TRIPLET OF INFRARED OH BANDS OF ZEOLITIC H-COMPLEXES

The phenomenon of the (A,B,C) triplet of infrared OH bands at similar to 2800, similar to 2400 and similar to 1700 cm(-1), well-known for strong X-OH ... Y molecular H-complexes in solutions, liquids, and solids, is studied for the first time for surface H-complexes using CD3CN and CCl3CN adsorption on deuterated H-ZSM5 and H-FeSil zeolites. A direct experimental proof is given that the minimum between the A and B bands of D-complexes occurs at nearly exactly the 2 delta(OD) in-plane bending overtone frequency of the perturbed OD group. This verifies the resonance theory of the (A,B) doublet by Claydon and Sheppard. In reference to zeolites this means that the similar to 2800 and similar to 2400 cm(-1) OH bands recently found in adsorption of many basic molecules on zeolitic OH groups are actually pseudobands, caused by the subdivision of the very broad v(OH) +/- kv(OH ... Y) superposition band of the perturbed OH groups by Evans transmission window at the 2 delta(OH) similar to 2600 cm(-1) frequency.