Metal hydrides and their use in hydrogen storage applications

A metal hydride of the formula (I):

• M1(M2)zHxRy (I)
• wherein
• M1 is a first metal selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and copper;
• M2 is one or more additional metals that have a total content of z;
• R, if present, is an organic group;
• x is about 0.5 to about 4.5;
• and
• y is 0 to about 0.5, and
• z is 0 to about 0.2;
• wherein
• (a) when M1 is vanadium, x is at least 2.4,
• (b) when M1 is copper, x is at least 1.0,
• (c) when M1 is titanium, x is at least 2.4, and
• (d) when M1 is nickel, x is at least 1.6;
• and wherein
• (i) R, when present, is bound to the metal center via a carbon atom in the R group;
• (ii) the metal hydride is stable as a bulk solid at room temperature;
• and
• (iii) the metal hydride is capable of absorbing and reversibly releasing hydrogen.