Methods and compositions for electrochemical deposition of metal rich layers in aqueous solutions

A composition comprising a first metal complex comprising a first reactive metal and a first electron withdrawing ligand wherein the first electron withdrawing ligand is OSO2R1, wherein R1 is halo;

• substituted or unsubstituted C6-C18-aryl;
• substituted or unsubstituted C1-C6-alkyl;
• and substituted or unsubstituted C6-C18-aryl-C1-C6-alkyl, and a second metal complex comprising a second reactive metal and a second electron withdrawing ligand wherein the second withdrawing ligand is N(SO3R1), wherein R1 is halo;
• substituted or unsubstituted C6-C18-aryl;
• substituted or unsubstituted C1-C6-alkyl;
• and substituted or unsubstituted C6-C18-aryl-C1-C6-alkyl, wherein the first reactive metal has a more negative reduction potential than the second reactive metal, wherein the first electron withdrawing ligand decreases the reduction potential of a metal center in the first metal complex below an over-potential for an evolution of hydrogen gas due to a water splitting and the second electron withdrawing ligand decreases the reduction potential of a metal center in the second metal complex below the over-potential for the evolution of hydrogen gas due to the water splitting, wherein the composition further comprises a substantially aqueous medium, wherein the first reactive metal and the second reactive metal can be deposited onto a substrate via electrochemical reduction and wherein the pH of the composition is from about 2 to about 5.