Metal complexes

1. A monometallic compound comprising a hexadentate tripodal ligand wherein three bidentate part-ligands, which may be identical or different, are coordinated to a metal selected from the group consisting of ruthenium, osmium, rhodium and iridium, and the three bidentate part-ligands are linked to one another via a bridge of formula (1):

wherein

the dashed bonds are the direct bonds from the bidentate part-ligands to the structure of formula (1);

X 1 is on each occurrence, identically or differently, CR 2 or O;

X 2 is on each occurrence, identically or differently, CR, P═O, B, or Si, which is optionally substituted, with the proviso that, when X 2 is P═O, B, or Si, which is optionally substituted, X 1 is O; and wherein substituents optionally present on X 1 and X 2 optionally define an aliphatic or heteroaliphatic ring system with themselves or with one another;

X 3 is on each occurrence, identically or differently, —CR═CR—, —CR═N—, —CR—NR″—, —C(═O)—O—, —C(═O)—NR″—, —C(═O)—S—, —C(═S)—O—, —C(═S)—S—;

R is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 1 ) 2 , CN, NO 2 , OR 1 , SR 1 , COOH, C(═O)N(R 1 ) 2 , Si(R 1 ) 3 , B(OR 1 ) 2 , C(═O)R 1 , P(═O)(R 1 ) 2 , S(═O)R 1 , S(═O) 2 R 1 , OSO 2 R 1 , a straight-chain alkyl group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, wherein the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more radicals R 1 , wherein one or more non-adjacent CH 2 groups are optionally replaced by R 1 C═CR 1 , C═C, Si(R 1 ) 2 , C═O, NR 1 , O, S, or CONR 1 , or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R 1 ; and wherein two or more radicals R which are bonded to X 1 and/or X 2 optionally define an aliphatic or heteroaliphatic ring system with one another; and wherein two radicals R when X 3 is —CR═CR— optionally define an aliphatic, heteroaliphatic, aromatic, or heteroaromatic ring system with one another; and wherein radicals R and R″ when X 3 is —CR—NR″— define a heteroaromatic ring system with one another;

R″ is on each occurrence, identically or differently, H, D, a straight-chain alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms or an alkenyl group having 2 to 20 C atoms, wherein the alkyl or alkenyl group in each case is optionally substituted by one or more radicals R 1 and wherein one or more non-adjacent CH 2 groups are optionally replaced by Si(R 1 ) 2 , or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R′;

R 1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 2 ) 2 , CN, NO 2 , OR 2 , SR 2 , Si(R 2 ) 3 , B(OR 2 ) 2 , C(═O)R 2 , P(═O)(R 2 ) 2 , S(═O)R 2 , S(═O) 2 R 2 , OSO 2 R 2 , a straight-chain alkyl group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, wherein the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more radicals R 2 , wherein one or more non-adjacent CH 2 groups are optionally replaced by R 2 C═CR 2 , C≡C, Si(R 2 ) 2 , C═O, NR 2 , O, S, or CONR 2 , or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R 2 ; wherein a plurality of substituents R 1 optionally define an aliphatic, heteroaliphatic, aromatic, or heteroaromatic ring system with one another;

furthermore, the groups R or R substituted with R 1 optionally form a ring system, and groups R and R 1 optionally form a ring system with one another;

R 2 is on each occurrence, identically or differently, H, D, F, or an aliphatic, aromatic, and/or heteroaromatic organic radical having 1 to 20 C atoms, wherein one or more H atoms are optionally replaced by F; and

wherein the bidentate part-ligands are selected, identically or differently on each occurrence, from the group consisting of structures of formulae (L-1), (L-2), (L-3), and (L-4):

wherein

the dashed bond is the direct bond from the part-ligand to the bridge of formula (1);

CyC is, identically or differently on each occurrence, an optionally substituted aryl or heteroaryl group having 5 to 14 aromatic ring atoms, which is coordinated to the metal via a carbon atom and which is connected to CyD via a covalent bond;

CyD is, identically or differently on each occurrence, an optionally substituted heteroaryl group having 5 to 14 aromatic ring atoms, which is coordinated to the metal via a nitrogen atom or via a carbene carbon atom and which is connected to CyC via a covalent bond; and

wherein a plurality of the optional substituents optionally defines a ring system with one another; and

the three bidentate ligands are optionally cyclised by a further bridge, in addition to the bridge of formula (1), to define a cryptate.

2. The monometallic compound of claim 1 , wherein the bridge of formula (1) is selected from the group consisting of structures of formulae (2) through (6):

wherein

R′ is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 1 ) 2 , CN, NO 2 , OR′, SR′, COOH, C(═O)N(R 1 ) 2 , C(═O)R 1 , P(═O)(R 1 ) 2 , S(═O)R 1 , S(═O) 2 R 1 , OSO 2 R 1 , a straight-chain alkyl group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, where the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more radicals R′, wherein one or more non-adjacent CH 2 groups are optionally replaced by R 1 C═CR 1 , C≡C, C═O, NR 1 , O, S, or CONR 1 , or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which in each case are optionally substituted by one or more radicals R 1 .

3. The monometallic compound of claim 1 , wherein the bridge of formula (1) is selected from the structures of the formulae (2a) and (2b)

4. The monometallic compound of claim 1 , wherein the bidentate part-ligands are each monoanionic and wherein the three bidentate part-ligands are either selected identically or two bidentate part-ligands are selected identically and the third bidentate part-ligand is selected differently from the first two bidentate part-ligands and wherein the coordinating atoms of the bidentate part-ligands are selected, identically or differently on each occurrence, from C, and/or N.

5. The monometallic compound of claim 1 , wherein the metal is Ir(III) and two of the bidentate part-ligands are coordinated to the iridium in each case via one carbon atom and one nitrogen atom or via two carbon atoms and the third of the bidentate part-ligands is coordinated to the iridium via one carbon atom and one nitrogen atom or via two carbon atoms or via two nitrogen atoms.

6. The monometallic compound of claim 1 wherein CyC is selected from the group consisting of structures of formulae (CyC-1) through (CyC-20):

wherein

the group is in each case bonded to CyD in (L-1) or (L-2) or to CyC in (L-4) at the position denoted by # and is coordinated to the metal at the position denoted by *; and

CyD is selected from the group consisting of structures of formulae (CyD-1) through (CyD-14):

wherein

the group is in each case bonded to CyC in (L-1) or (L-2) or to CyD in (L-3) at the position denoted by # and is coordinated to the metal at the position denoted by *; and

wherein

R is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 1 ) 2 , CN, NO 2 , OR 1 , SR 1 , COOH, C(═O)N(R 1 ) 2 , Si(R 1 ) 3 , B(OR 1 ) 2 , C(═O)R 1 , P(═O)(R 1 ) 2 , S(═O)R 1 , S(═O) 2 R 1 , OSO 2 R 1 , a straight-chain alkyl group having 1 to 20 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, wherein the alkyl, alkenyl, or alkynyl group in each case is optionally substituted by one or more radicals R 1 , wherein one or more non-adjacent CH 2 groups are optionally replaced by R 1 C=CR 1 , C═C, Si(R 1 ) 2 , C═O, NR 1 , O, S, or CONR 1 , or an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R 1 ; and wherein two or more radicals R which are bonded to X 1 and/or X 2 optionally define an aliphatic or heteroaliphatic ring system with one another; and wherein two radicals R when X 3 is —CR═CR— optionally define an aliphatic, heteroaliphatic, aromatic, or heteroaromatic ring system with one another; and wherein radicals R and R″ when X 3 is —CR—NR″— define a heteroaromatic ring system with one another; and wherein two radicals R optionally define an aliphatic, heteroaliphatic, aromatic, or heteroaromatic ring system with one another:

X is on each occurrence, identically or differently, CR or N, with the proviso that a maximum of two X per ring are N;

W is on each occurrence, identically or differently, NR, O, or S; and

wherein the bonding of these groups to the bridge of formula (1) is via the position denoted by “o” and the corresponding X is C.

7. The monometallic compound of claim 1 , wherein the bidentate part-ligands are selected from the group consisting of structure of formulae (L-1-1), (L-1-2), (L-2-1), (L-2-2), (L-2-3), and (L-5) through (L-34):

8. The monometallic compound of claim 1 , wherein the monometallic compound comprises two substituents R, which are bonded to adjacent carbon atoms and which define a ring of one of formulae (43) through (49) with one another:

wherein

the dashed bonds indicate the linking of the two carbon atoms in the ligand;

A 1 and A 3

are, identically or differently on each occurrence, C(R 3 ) 2 , O, S, NR 3 , or C(=0);

A 2 is C(R 1 ) 2 , 0, S, NR 3 , or C(═O);

G is an alkylene group having 1, 2, or 3 C atoms, which is optionally substituted by one or more radicals R 2 , or is —CR 2 ═CR 2 — or an ortho-linked arylene or heteroarylene group having 5 to 14 aromatic ring atoms, which is optionally substituted by one or more radicals R 2 ;

R 3 is, identically or differently on each occurrence, H, D, F, a straight-chain alkyl or alkoxy group having 1 to 10 C atoms, a branched or cyclic alkyl or alkoxy group having 3 to 10 C atoms, wherein the alkyl or alkoxy group in each case is optionally substituted by one or more radicals R 2 , wherein one or more non-adjacent CH 2 groups are optionally replaced by R 2 C═CR 2 , C═C, Si(R 2 ) 2 , C═O, NR 2 , O, S, or CONR 2 , or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which in each case is optionally substituted by one or more radicals R 2 , or an aryloxy or heteroaryloxy group having 5 to 24 aromatic ring atoms, which is optionally substituted by one or more radicals R 2 ; and wherein two radicals R 3 bonded to the same carbon atom optionally define an aliphatic or aromatic ring system with one another to form a spiro system; and wherein R 3 optionally defines an aliphatic ring system with an adjacent radical R or R 1 , with the proviso that no two heteroatoms are bonded directly to one another and no two groups C═O are bonded directly to one another in these groups.

9. A process for preparing the monometallic compound of claim 1 , comprising reacting a free ligand with a metal alkoxides of formula (50), a metal ketoketonate of formula (51), a metal halide of formula (52), or a metal carboxylate of formula (53), or with a metal compound which carries both alkoxide and/or halide and/or hydroxyl and also ketoketonate radicals:

wherein

M is the metal of the monometallic compound being prepared;

n is the valency of the metal M; and

Hal is F, Cl, Br, or I; and

wherein the metal starting materials are optionally in the form of a corresponding hydrate.

10. An oligomer, polymer, or dendrimer comprising one or more monometallic compounds of claim 1 , wherein one or more bonds from the monometallic compound to the polymer, oligomer, or dendrimer are present instead of one or more hydrogen atoms and/or substituents.

11. A formulation comprising at least one monometallic compound of claim 1 and at least one solvent.

12. A formulation comprising at least one oligomer, polymer, or dendrimer of claim 10 and at least one solvent.

13. An electronic device comprising at least one monometallic compound of claim 1 .

14. An electronic device comprising at least one oligomer, polymer, or dendrimer of claim 10 .

15. The electronic device of claim 13 , wherein the electronic device is an organic electroluminescent device and the at least one monometallic compound is employed as an emitting compound in one or more emitting layers or as a hole-blocking material in a hole blocking layer or as an electron-transport material in an electron-transport layer.