Organopolysiloxane composition which crosslinks to give an elastomer, resulting, when it is crosslinked, in a thermally stable elastomer, comprising at least one thermal stabilizer which is an iron complex having the formula: Fe[L x;B y;C z] in which: - x, y and z represent the number of moles of each species with: - 0< x ≤ 3, 0 ≤ y ≤ (3-x-z); 0 ≤ z ≤ (3-x-y) and [x+y+z] = 3, - the ligand L is a β-diketonate derived from a β-diketone of formula below: in which: - R 1 is a group represented by formula below: n -Φ- in which: - n is an integer from 0 to 5, - Φ is a phenyl, and - each group Y, which may be identical or different, is a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based chain containing from 1 to 40 carbon atoms, an alkoxy, a silylated group and a halogen atom; - the group R 2 represents a group having the same definition as R 1, identical or different than R 1, a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based radical containing from 1 to 40 carbon atoms, optionally interrupted with one or more oxygen atoms, an aralkyl radical, an alkoxy and a silylated group; - the group R 3 represents a hydrogen atom or a hydrocarbon-based group containing from 1 to 40 carbon atoms, optionally interrupted with one or more heteroatom(s), and - it being possible for R 1, R 2 and R 3 to be optionally connected together in pairs by a hydrocarbon-based chain optionally interrupted with one or more heteroatom(s), so as to form a ring, and - the ligands B and C, which may be identical or different, are carboxylates. - x, y and z represent the number of moles of each species with: - 0< x ≤ 3, 0 ≤ y ≤ (3-x-z); 0 ≤ z ≤ (3-x-y) and [x+y+z] = 3, - the ligand L is a β-diketonate derived from a β-diketone of formula below: in which: - R 1 is a group represented by formula below: n -Φ- in which: - n is an integer from 0 to 5, - Φ is a phenyl, and - each group Y, which may be identical or different, is a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based chain containing from 1 to 40 carbon atoms, an alkoxy, a silylated group and a halogen atom; - the group R 2 represents a group having the same definition as R 1, identical or different than R 1, a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based radical containing from 1 to 40 carbon atoms, optionally interrupted with one or more oxygen atoms, an aralkyl radical, an alkoxy and a silylated group; - the group R 3 represents a hydrogen atom or a hydrocarbon-based group containing from 1 to 40 carbon atoms, optionally interrupted with one or more heteroatom(s), and - it being possible for R 1, R 2 and R 3 to be optionally connected together in pairs by a hydrocarbon-based chain optionally interrupted with one or more heteroatom(s), so as to form a ring, and - the ligands B and C, which may be identical or different, are carboxylates. - R 1 is a group represented by formula below: n -Φ- in which: - n is an integer from 0 to 5, - Φ is a phenyl, and - each group Y, which may be identical or different, is a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based chain containing from 1 to 40 carbon atoms, an alkoxy, a silylated group and a halogen atom; - n is an integer from 0 to 5, - Φ is a phenyl, and - each group Y, which may be identical or different, is a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based chain containing from 1 to 40 carbon atoms, an alkoxy, a silylated group and a halogen atom; - the group R 2 represents a group having the same definition as R 1, identical or different than R 1, a hydrogen atom or a group chosen from the group constituted of a hydrocarbon-based radical containing from 1 to 40 carbon atoms, optionally interrupted with one or more oxygen atoms, an aralkyl radical, an alkoxy and a silylated group; - the group R 3 represents a hydrogen atom or a hydrocarbon-based group containing from 1 to 40 carbon atoms, optionally interrupted with one or more heteroatom(s), and - it being possible for R 1, R 2 and R 3 to be optionally connected together in pairs by a hydrocarbon-based chain optionally interrupted with one or more heteroatom(s), so as to form a ring, and - the ligands B and C, which may be identical or different, are carboxylates.