Microwave Detection of Wet Triacetone Triperoxide (TATP): Non‐Covalent Forces and Water Dynamics

The water adducts of triacetone triperoxide (TATP) have been observed by using broadband rotational spectroscopy. This work opens a new way for the gas‐phase detection of this improvised explosive. The observed clusters exhibit unusual water dynamics and rarely observed multicenter interactions. TATP‐H 2 O is formed from the D 3 symmetry conformer of TATP with water lying close to the C 3 axis. Water rotation around this axis with a very low barrier gives rise to the rotational spectrum of a symmetric top. The main interaction of the monohydrate is a four‐center trifurcated donor O w ‐H⋅⋅⋅O hydrogen bond, not observed previously in the gas phase, reinforced by a weak four‐center trifurcated acceptor C−H⋅⋅⋅O w interaction. Surprisingly, all structural signatures show the weakness of these interactions. The complex TATP‐(H 2 O) 2 is formed from the monohydrated TATP by the self‐association of water.