Hydrogen alanates

Common reducing agents are hydrogen in the presence of metallic or complex catalysts (e.g. Ni, Pd, Pt, Ru, Rh), hydrides (e.g. alanes, boranes, LIAIH, NaBHJ, reducing metals (e.g. Li, Na, Mg, Ca, Zn), and low-valent compounds of nitrogen (e.g. NjHj, NjHJ, phosphorus (e.g. triethyl phosphite, triphenyiphosphine), and sulfur (e.g. HO-CHj-SOjNa = SFS, sodium dithionite = Na S O. ... 

In the first three cycles, the capacity of the alanate is high for both materials, the titanium metal-doped and the nitride-doped material. However, after 15 cycles the hydrogen capacity decreases significantly below 4% for the titanium metal-doped sample, whereas for the nitride-doped sample the capacity remains high at about 5% hydrogen. 

Closely related to, but distinct from, the anionic boron and aluminum hydrides are the neutral boron (borane, BH3) and aluminum (alane, A1H3) hydrides. These molecules also contain hydrogen that can be transferred as hydride. Borane and alane differ from the anionic hydrides in being electrophilic species by virtue of the vacant p orbital and are Lewis acids. Reduction by these molecules occurs by an intramolecular hydride transfer in a Lewis acid-base complex of the reactant and reductant. 

B. M. Lichstein, and D. D. Perry The Chemistry of Alane, I. Some Observations on the Effect of the Coordinating Base on the Aluminium-Hydrogen Absorption in the Infrared. Inorg. Chem. 2, 650 (1963). 

Fig. 1. Exact and approximate energy levels of the hydrogen atom in varying magnetic fields from Introduction to Magnetic Resonance by Alan Carrington and Andrew D. McLachlan, p. 20. Harper, New York, 1967. Reprinted by permission of Harper Row, Publishers, Inc.

Hydrogen Absorption and Desorption Properties of Sodium Alanates... 

Bellosta von Colbe, J.M., B. Bogdanovic, M. Felderhoff, A. Pommerin, and F. Schuth, Recording of hydrogen evolution—a way for controlling the doping process of sodium alanate by ball milling, /. Alloys Compd., 370, 104-109, 2004. 

Ritchson, E., Nanotechnology and hydrogen storage in complex metal hydrides, available at http //engineering.purdue.edu/ChE/webpublications/ericjri/physics and chemistry of the alanate, March 2007. 

Ahluwalia, R.K., Sodium alanate hydrogen storage system for automotive fuel cells, Int.. Hydrogen Energ, 32(9), 1251-1261, 2007. 

When Group VI carbonyl complexes were reacted with alane or Cp2NbH3 reduction of CO to ethylene was noted.- - Ethylene was the primary product of the Cp2NbH3 reduction although it subsequently was hydrogenated to ethane. Masters and co-workers suggested that ethylene was formed through an alkylidene dimerization as shown below. 

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