A composition comprising: ingredients comprising a catalytically active reaction product of i) an iron carbonyl compound having general formula (i): Fe a b, where subscript a is an integer with a value ranging from 1 to 3, subscript b is an integer with a value ranging from 5 to 12; and ii) a silicon containing ligand that coordinates with Fe, where the silicon containing ligand has, per molecule, at least one atom of Si and at least one aliphatically unsaturated group; and an aliphatically unsaturated compound having an average, per molecule, of one or more aliphatically unsaturated organic groups capable of undergoing hydrosilylation reaction; and optionally an SiH functional compound having an average, per molecule, of one or more silicon bonded hydrogen atoms; which is distinct from ingredients and; with the proviso that when ingredient lacks a silicon bonded hydrogen atom, then the composition includes ingredient; wherein the silicon containing ligand that coordinates with Fe is unit formula: (R 1 R 2 2 Si-R 3 1/2) c (R 1 R 2 Si-R 3 2/2) d (R 2 Si-R 3 3/2) e (Si-R 3 4/2) f (R 2 3 Si-R 3 1/2) g (R 2 2 SiR 3 2/2) h; where subscript c is 0 or more; subscript d is 0 or more; subscript e is 0 or more; subscript f is 0 or more; with the proviso that ( c + d + e + f) > 0; subscript g is 0 or more; subscript h is 0 or more; each R 1 is independently an alkynyl group or an alkenyl group; each R 2 is independently an alkyl group, a cycloalkyl group, or an aryl group; and each R 3 is an oxygen atom or an amino group of formula =NH. a catalytically active reaction product of i) an iron carbonyl compound having general formula (i): Fe a b, where subscript a is an integer with a value ranging from 1 to 3, subscript b is an integer with a value ranging from 5 to 12; and ii) a silicon containing ligand that coordinates with Fe, where the silicon containing ligand has, per molecule, at least one atom of Si and at least one aliphatically unsaturated group; and i) an iron carbonyl compound having general formula (i): Fe a b, where subscript a is an integer with a value ranging from 1 to 3, subscript b is an integer with a value ranging from 5 to 12; and ii) a silicon containing ligand that coordinates with Fe, where the silicon containing ligand has, per molecule, at least one atom of Si and at least one aliphatically unsaturated group; and an aliphatically unsaturated compound having an average, per molecule, of one or more aliphatically unsaturated organic groups capable of undergoing hydrosilylation reaction; and with the proviso that when ingredient lacks a silicon bonded hydrogen atom, then the composition includes ingredient; wherein the silicon containing ligand that coordinates with Fe is unit formula: (R 1 R 2 2 Si-R 3 1/2) c (R 1 R 2 Si-R 3 2/2) d (R 2 Si-R 3 3/2) e (Si-R 3 4/2) f (R 2 3 Si-R 3 1/2) g (R 2 2 SiR 3 2/2) h; where subscript c is 0 or more; subscript d is 0 or more; subscript e is 0 or more; subscript f is 0 or more; with the proviso that ( c + d + e + f) > 0; subscript g is 0 or more; subscript h is 0 or more; each R 1 is independently an alkynyl group or an alkenyl group; each R 2 is independently an alkyl group, a cycloalkyl group, or an aryl group; and each R 3 is an oxygen atom or an amino group of formula =NH.