Metal complexes

A compound comprising a ligand of formula (1) coordinated to two metals, wherein the metals are the same or different and are selected from iridium and rhodium:

• wherein
• V is a group of formula (2) or (3):
• wherein
• the dotted lines denote the bonds to X3;
• L1 is the same or different in each instance and is a bidentate monoanionic sub-ligand, wherein all sub-ligands L1 coordinate to one of the two metals;
• L2 is the same or different in each instance and is a bidentate monoanionic sub-ligand, where all sub-ligands L2 coordinate to the one of the two metals not coordinated to L1;
• X1 is the same or different in each instance and is CR or N;
• X2 is the same or different in each instance and is CR or N or two adjacent X2 groups together are NR, O, or S, so as to define a five-membered ring, and the remaining X2 are the same or different in each instance and are CR or N;
• or two adjacent X2 groups together are CR or N when one of the X3 groups in the cycle is N, so as to define a five-membered ring;
• with the proviso that not more than two adjacent X2 groups are N;
• X3 is C in each instance or one X3 group is N and the other X3 groups in the same cycle are C;
• with the proviso that two adjacent X2 groups together are CR or N when one of the X3 groups in the cycle is N;
• A1 is the same or different in each instance and is C(R)2 or O;
• A2 is the same or different in each instance and is CH, CD, or B, with the proviso that, when A2 is B, A1 is O;
• R is the same or different in each instance and is H, D, F, Cl, Br, I, N(R1)2, CN, NO2, OR1, SR1, COOH, C(═O)N(R1)2, Si(R1)3, B(OR1)2, C(═O)R1, P(═O)(R1)2, S(═O)R1, S(═O)2R1, OSO2R1, COO(cation), SO3(cation), OSO3(cation), OPO3(cation)2, O(cation), N(R1)3(anion), P(R1)3(anion), a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more R1 radicals, wherein one or more nonadjacent CH2 groups are optionally replaced by Si(R1)2, C═O, NR1, O, S, or CONR1, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and is optionally substituted in each case by one or more R1 radicals;
• and wherein two R radicals together optionally define a ring system;
• R1 is the same or different in each instance and is H, D, F, Cl, Br, I, N(R2)2, CN, NO2, OR2, SR2, Si(R2)3, B(OR2)2, C(═O)R2, P(═O)(R2)2, S(═O)R2, S(═O)2R2, OSO2R2, COO(cation), SO3(cation), OSO3(cation), OPO3(cation)2, O(cation), N(R2)3(anion), P(R2)3(anion), a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more R2 radicals, wherein one or more nonadjacent CH2 groups are optionally replaced by Si(R2)2, C═O, NR2, O, S, or CONR2, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and is optionally substituted in each case by one or more R2 radicals;
• and wherein two or more R1 radicals together optionally define a ring system;
• R2 is the same or different in each instance and is H, D, F, or an aliphatic, aromatic, or heteroaromatic organic radical having 1 to 20 carbon atoms, wherein one or more hydrogen atoms is also optionally replaced by F;
• cation is the same or different in each instance and is selected from the group consisting of proton, deuteron, alkali metal ions, alkaline earth metal ions, ammonium, tetraalkylammonium, and tetraalkylphosphonium;
• anion is the same or different in each instance and is selected from the group consisting of halides, carboxylates R2—COO−, cyanide, cyanate, isocyanate, thiocyanate, thioisocyanate, hydroxide, BF4−, PF6−, B(C6F5)4−, carbonate and sulfonates.