Metal hydride materials react with BZ.sub.3 compounds in the presence of ligand to form BH.sub.3-L compounds. A compound of the formula HBZ.sub.2 is prepared from a compound of the formula BZ.sub.3 by reacting a first amount of a compound of the formula HBZ.sub.2 with a metal hydride material "MH" and a compound "L" to form a material of the formula BH.sub.3-L, and then reacting the BH.sub.3-L thus formed with a compound of the formula BZ.sub.3 to form HBZ.sub.2 in a second amount greater than the first amount of HBZ.sub.2. Z is selected from alkoxy, aryloxy, amido, arylamido, doubly substituted alkoxy, doubly substituted aryloxy, doubly substituted amido, doubly substituted arylamido, alkoxy-amido, and aryloxy-arylamido. When Z is bidentate, then HBZ.sub.2 has a ring structure. "L" is selected from ethers, aromatic ethers, amines, aromatic amines, heterocyclic nitrogen compounds, sulfides, aromatic sulfides, and heterocyclic sulfur compounds. "L" becomes a ligand in the BH.sub.3-L material.
STATEMENT REGARDING FEDERAL RIGHTS
 This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy. The government has certain rights in the invention.