Hydrazine bisalane is a potential compound for chemical hydrogen storage. A theoretical study.

Electronic structure calculations suggest that hydrazine bisalane (AlH(3)NH(2)NH(2)AlH(3), alhyzal) is a promising compound for chemical hydrogen storage (CHS). Calculations are carried out using the coupled-cluster theory CCSD(T) with the aug-cc-pVTZ basis set. Potential energy surfaces are constructed to probe the formation of, and hydrogen release from, hydrazine bisalane which is initially formed from the reaction of hydrazine with dialane.

Formation and hydrogen release of hydrazine bisborane: transfer vs. attachment of a borane.

The reactivity of hydrazine in the presence of diborane has been investigated using ab initio quantum chemical computations (MP2 and CCSD(T) methods with the aug-cc-pVTZ basis set). Portions of the relevant potential energy surface were constructed to probe the formation mechanism of the hydrazine diborane (BH(3)BH(3)NH(2)NH(2)) and hydrazine bisborane (BH(3)NH(2)NH(2)BH(3)). The differences between both adducts are established.

Formation and decomposition of chemically activated and stabilized hydrazine.

Recombination of two amidogen radicals, NH(2) (X(2)B1), is relevant to hydrazine formation, ammonia oxidation and pyrolysis, nitrogen reduction (fixation), and a variety of other N/H/X combustion, environmental, and interstellar processes. We have performed a comprehensive analysis of the N(2)H(4) potential energy surface, using a variety of theoretical methods, with thermochemical kinetic analysis and master equation simulations used to treat branching to different product sets in the chemically activated NH(2) + NH(2) process. For the first time, iminoammonium ylide (NH(3)NH), the less stable isomer of hydrazine, is involved in the kinetic modeling of N(2)H(4).

Fast reactions of hydroxycarbenes: tunneling effect versus bimolecular processes.

Different uni- and bimolecular reactions of hydroxymethylene, an important intermediate in the photochemistry of formaldehyde, as well as its halogenated derivatives (XCOH, X = H, F, Cl, Br), have been considered using high-level CCSD(T)/CBS quantum chemical methods. The Wentzel-Kramers-Brillouin (WKB) and Eckart approximations were applied to estimate the tunneling rate constant of isomerization of trans-HCOH to H(2)CO, and the WKB procedure was found to perform better in this case. In agreement with recent calculations and experimental observations [Schreiner et al.

Production of hydrogen from reactions of methane with boranes.

The reactions of methane with different hydrides have been investigated using quantum chemical calculations (MP2 and CCSD(T) methods with the aug-cc-pVnZ one-electron functions extrapolated to the basis set limits). The hydrides of the elements of the second and third row, and also GaH(3), with an electronegativity smaller than the value of hydrogen (LiH, Li(2)H(2), BeH(2), NaH, MgH(2), BH(3), AlH(3), B(2)H(6), Al(2)H(6), SiH(4), PH(4) and GaH(3)) have been considered. Reactions of CH(4) with either BH(3) or LiH are characterized by the lowest energy barriers.

The effect of the NH2 substituent on NH3: hydrazine as an alternative for ammonia in hydrogen release in the presence of boranes and alanes.

Potential energy surfaces for H(2) release from hydrazine interacting with borane, alane, diborane, dialane and borane-alane were constructed from MP2/aVTZ geometries and zero point energies with single point energies at the CCSD(T)/aug-cc-pVTZ level. With one borane or alane molecule, the energy barrier for H(2)-loss of approximately 38 or 30 kcal mol(-1) does not compete with the B-N or Al-N bond cleavage ( approximately 30 or approximately 28 kcal mol(-1)). The second borane or alane molecule can play the role of a bifunctional catalyst.