Organo-metallic analytes for nonaqueous redox flow batteries

An organometallic complex for use as a Non-Aqueous Redox-Flow Battery (NRFB) analyte represented by formula I:

• or a salt thereof, wherein M is a Group 13 metal and L1 and L2 are independently selected from bis (imino)pyridine compounds of Formula II:
• wherein R1, R2, and R3 are independently selected from a hydrogen atom;
• hydrocarbon groups having one to twenty carbon atoms with optional inclusion of one or more heteroatoms selected from oxygen, nitrogen, silicon, sulfur, and halogen atoms, wherein the hydrocarbon group is attached to the pyridine ring by a carbon atom;
• halogen atoms;
• hydroxy groups;
• nitrile groups;
• amino groups —NR11R12;
• ether groups-OR;
• carboxamide groups —C(O)NR11R12 or —NR11C(O)R;
• keto groups —C(O)R, carboxylic acid groups —C(O)OH or salt thereof;
• ester groups —C(O)OR;
• sulfonate groups;
• phosphonate groups;
• silyl groups, and nitrate groups;
• wherein R11 and R12 are independently selected from a hydrogen atom and hydrocarbon groups and R is a hydrocarbon group;
• R4 and R5 are independently selected from a hydrogen atom;
• hydrocarbon groups having one to twenty carbon atoms with optional inclusion of one or more heteroatoms selected from oxygen, nitrogen, sulfur, and halogen atoms, wherein the hydrocarbon group is attached to the imine group by a carbon atom;
• and
• Ar1 and Ar2 are independently selected from substituted phenyl groups;
• with the proviso that when R1, R2, and R3 are hydrogen, and R4 and R5 are phenyl groups, Ar1 and Ar2 are not 2-methoxyphenyl groups.