Provided is a catalyst for producing hydrogen, which catalyst has higher performance than conventional catalysts since, for example, it exhibits a certain high level of activity in an aqueous formic acid solution at high concentration even without addition of a solvent, amine and/or the like. The metal phosphine complex is a metal phosphine complex represented by General Formula (1): MH.sub.m(CO)L.sub.n, wherein M represents an iridium, iron, rhodium or ruthenium atom; in cases where M is an iridium or rhodium atom, m=3 and n=2, and in cases where M is an iron or ruthenium atom, m=2 and n=3; and the number n of Ls each independently represent a tri-substituted phosphine represented by General Formula (2): PR.sup.1R.sup.2R.sup.3. The catalyst for producing hydrogen comprises the metal phosphine complex as a constituent component.

A composition contains (A) a hydrosilylation reaction catalyst and (B) an aliphatically unsaturated compound having an average, per molecule, of one or more aliphatically unsaturated organic groups capable of undergoing hydrosilylation reaction. The composition is capable of reacting via hydrosilylation reaction to form a reaction product, such as a silane, a gum, a gel, a rubber, or a resin. Ingredient (A) contains a metal-ligand complex that can be prepared by a method including reacting a metal precursor and a ligand.

Provided is a method of decomposing a crosslinked rubber that includes: a first decomposition step of decomposing a crosslinked rubber containing a diene rubber, using a catalyst represented by the following general formula (1), (2), or (3), where Mis ruthenium, molybdenum, etc., X.sup.1, X.sup.2, L.sup.1, L.sup.2, and L.sup.3 each independently represent a ligand, R.sup.1, R.sup.2, and R.sup.3 each independently represent hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, etc. (these groups may be substituted by one or more alkyl groups, halogens, alkoxy groups, etc.), L.sup.1 and L.sup.2, R.sup.1 and R.sup.2, and L.sup.1 and R.sup.1 may respectively bond with each other to form rings; and a second decomposition step of pyrolyzing a decomposition product obtained by the first decomposition step under an inert gas atmosphere and in the absence of a catalyst at a temperature of 300 C. to 450 C.

##STR00001##

Provided is a method of decomposing a crosslinked rubber that includes: a first decomposition step of decomposing a crosslinked rubber containing a diene rubber, using a catalyst represented by the following general formula (1), (2), or (3), where M is ruthenium, molybdenum, etc., X.sup.1, X.sup.2, L.sup.1, L.sup.2, and L.sup.3 each independently represent a ligand, R.sup.1, R.sup.2, and R.sup.3 each independently represent hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, etc. (these groups may be substituted by one or more alkyl groups, halogens, alkoxy groups, etc.), L.sup.1 and L.sup.2, R.sup.1 and R.sup.2, and L.sup.1 and R.sup.1 may respectively bond with each other to form rings; and a second decomposition step of pyrolyzing a decomposition product obtained by the first decomposition step under an inert gas atmosphere and in the absence of a catalyst at a temperature of 600 C. to 950 C.

##STR00001##

Disclosed herein are embodiments of a chiral Pd(0) precatalyst that exhibits bench-top and/or solution stability against degradation and/or oxidation. Also disclosed are method embodiments for making the Pd(0) precatalyst and methods for using the same in enantioselective chemical reactions, such as carbon-element bond formation.