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Threshold Collision-Induced Dissociation of Proton-Bound Hydrazine and Dimethylhydrazine Clusters

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journal contribution
posted on 22.11.2016 by Christopher P. McNary, P. B. Armentrout
Threshold collision-induced dissociation (TCID) using a guided ion beam tandem mass spectrometer is performed on (N2H4)nH+ where n = 2–4 and on the proton-bound unsymmetrical 1,1-dimethyl­hydrazine (UDMH) dimer complex. The primary dissociation pathway for all reactants consists of loss of a single hydrazine (or UDMH) molecule followed by the sequential loss of additional hydrazine molecules at higher collision energies for n = 3 and 4. The data were analyzed using a statistical model after accounting for internal and kinetic energy distributions, multiple collisions, and kinetic shifts to obtain 0 K bond dissociation energies (BDEs). These are also converted to values at room temperature by using a rigid rotor/harmonic oscillator approximation and theoretical molecular constants. Experimental BDEs are compared to theoretical BDEs determined at the B3LYP, M06, mPW1PW91, PBE0, MP2­(full), and CCSD­(T) levels of theory with and without empirical dispersion with a 6-311+G­(2d,2p) basis set. The structures of all clusters are explored and exhibit extensive hydrogen bonding.