Polymetallic precursors and compositions and methods for making supported polymetallic nanocomposites

A polymetallic precursor having at least one first metal and at least one second metal and comprising at least one metal-ligand-metal group represented by the formula:

• Mn—X—M′p,
• wherein M is an atom of the first metal;
• X is a thermally degradable ligand having a degradation temperature lower than degradation temperatures of M and M′;
• M′ is an atom of the first metal or the second metal;
• and n and p are each at least one, and the precursor is selected from the group consisting of Pt(triphenylphosphine)(Cl)-(μ-Cl2)Ru(Cl)(trihapto:trihapto-2,7-dimethyloctadienediyl);
• {Pt3[μ-bis(diphenylphosphino)methane]3(Ru)(pentahapto-cyclopentadienyl)}[hexafluorophosphate];
• [Ru(μ-2,3-bis(2-pyridyl)quinoxaline)PtCl2)3][tetrafluoroborate]2;
• {Pt3[μ-bis(diphenylphosphino)methane]3(μ3-Mo)(pentahapto-cyclopentadienyl)(CO)}[hexafluorophosphate];
• {Pt3[bis(diphenylphosphino)methane]3(μ3-Mo)(pentahapto-cyclopentadienyl)(CO)}[tetraphenylborate];
• {Pt3[μ-bis(diphenylphosphino)methane]3[μ4-Hg—Ru(pentahapto-cyclopentadienyl)(CO)2]2}[hexafluorophosphate]2;
• [Ru(2,2′-bipyridine)2(μ-bipyrimidine)PtCl2][tetrafluoroborate]2;
• Pt(dihaptoethylene)(Cl)(μ-Cl)2Ru (Cl)(trihapto:trihapto-2,7-dimethyloctadienediyl);
• and {Pt3(μ-W)(pentahapto-cyclopentadienyl) (CO)[μ-bis(diphenylphosphino)-methane]3}[hexafluorophosphate].

A method of making a supported polymetallic nanoparticle, the method comprising

• (a) contacting a support with a polymetallic precursor comprising at least one first metal and at least one second metal and at least one metal-ligand-metal group represented by the formula:
• Mn—X—M′p,
• wherein M is an atom of the first metal;
• X is a thermally degradable ligand having a degradation temperature lower than degradation temperatures of M and M′ and X is selected from the group consisting of a single atom, compound or moiety having an atom selected from the group consisting of a halogen, a mercury atom, a phosphorus atom, an atom from Groups 14-17 of the Periodic Table;
• organic ligands selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, aralkyl, alkylphosphino, arylphosphino, alkylsulfide, arylsulfide, alkylselenide, arylselenide, arlkylmercuric, and arylmercuric;
• ammonia;
• amine;
• alkene;
• heteroatomic aromatic molecules;
• arsenes;
• and derivatives thereof;
• M′ is an atom of the first metal or the second metal;
• and n and p are each at least one;
• and
• (b) heating the contacted support in the substantial absence of an oxidizing agent to form a supported polymetallic nanoparticle comprising the first metal and the second metal at a selected atomic ratio, wherein the selected atomic ratio is approximately equal to a stoichiometric ratio of the first metal to the second metal in the polymetallic precursor.

A supported nanocomposite comprising an electrically conductive support and a plurality of polymetallic nanoparticles, wherein the polymetallic nanoparticles comprise at least one first metal and at least one second metal and are formed from a polymetallic precursor comprising a metal-ligand-metal group represented by the formula

• Mn—X—M′p,
• wherein M is an atom of the first metal;
• X is a thermally degradable ligand having a degradation temperature lower than degradation temperatures of M and M′ and X is selected from the group consisting of a single atom, compound or moiety having an atom selected from the group consisting of a halogen, a mercury atom, a phosphorus atom, an atom from Groups 14-17 of the Periodic Table;
• organic ligands selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, aralkyl, alkylphosphino, arylphosphino, alkylsulfide, arylsulfide, alkylselenide, arylselenide, arlkylmercuric, and arylmercuric;
• ammonia;
• amine;
• alkene;
• heteroatomic aromatic molecules;
• arsenes;
• and derivatives thereof;
• M′ is an atom of the first metal or the second metal;
• and n and p are each at least one, and a stoichiometric ratio of the first metal atoms to the second metal atoms in the polymetallic precursor is approximately equal to a selected atomic ratio of the first metal atoms to the second metal atoms in the polymetallic nanoparticles.