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

Abstract

Threshold collision-induced dissociation (TCID) using a guided ion beam tandem mass spectrometer is performed on (NH)H 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.

Hydrazine and its Derivatives: Role on Nitrogen Dioxide Hydrolysis and Ensuing Nucleation in the Atmosphere

“…As a source of HONO, the reactions of HD/MMH+N 2 O 4 are extensively investigated in experiment and theory [24] . HD, as a high moisture absorbent, is usually present in the form of N 2 H 4 ⋅H 2 O, [29] and its hydrates and protonated‐hydrates are widely studied in compound organic chemistry [30–31] . Turpin et al.…”

“…[24] HD, as a high moisture absorbent, is usually present in the form of N 2 H 4 •H 2 O, [29] and its hydrates and protonated-hydrates are widely studied in compound organic chemistry. [30][31] Turpin et al have noted that organic nitrates can be formed in the wet aerosols with the presence of NO x . [32] Hence the effect of H 2 O on the atmospheric reactions in the presence of HD and MMH should be further taken into consideration.…”

Infrared multiple photon dissociation action spectroscopy of protonated unsymmetrical dimethylhydrazine and proton-bound dimers of hydrazine and unsymmetrical dimethylhydrazine

“…In previous studies, we have used guided ion beam tandem mass spectrometry and quantum chemistry to explore the thermochemistry of protonated hydrazine and UDMH and their clusters. [14][15][16] Protonated hydrazine, N 2 H 5 + , was observed to dissociate by homolytic and heterolytic N-N bond cleavages. 16 The thresholds for these processes showed that these dissociations occur along non-adiabatic pathways forming the excited NH 3 + ( 2 A 2 00 ) + NH 2 ( 2 A 1 ) and NH 2 + ( 1 A 1 ) + NH 3 ( 1 A 1 ) product asymptotes, respectively.…”

“…16 For the (N 2 H 4 ) n H + clusters where n = 2-4, the primary dissociation pathway for all reactants consists of loss of a single hydrazine molecule followed by the sequential loss of additional hydrazine molecules at higher collision energies for n = 3 and 4, such that sequential binding energies could be ascertained. 15 In that study, a theoretical potential energy surface (PES) that links four low-energy conformers of the (N 2 H 4 ) 2 H + dimer was characterized. The protonbound dimer of UDMH dissociates by loss of neutral UDMH, such that the dimer bond dissociation energy (BDE) could be measured.…”

“…Finally, the thermodynamics for hydration of protonated hydrazine and UDMH have also been examined by determining BDEs for loss of water from (N 2 H 4 )H + (H 2 O) n , where n = 1 and 2, and (UDMH)H + (H 2 O). 14 A number of different theoretical approaches were utilized and yielded differing results in our previous work on the dissociation thermochemistry of N 2 H 5 + , 16 (N 2 H 4 ) n H + clusters where n = 2-4 and (UDMH) 2 H + , 15 and hydrated systems, (N 2 H 4 )H + (H 2 O) n where n = 1 and 2 and (UDMH)H + (H 2 O). 14 In the N 2 H 5 + system where covalent bonds are being cleaved, B3LYP did not perform well, but this system is small enough that CCSD(T) calculations could be performed and reproduced the observed (and literature) thermochemistry well.…”