Transition metal complexes with bridged carbene ligands and use thereof in OLEDs

1. A cyclometalated carbene complex of the general formula (I)

in which the symbols are each defined as follows:

M is a metal atom selected from the group consisting of metals of group IB, IIB, IIIB, IVB, VB, VIIB, VIIB, VIIIB, the lanthanides and IIIA of the Periodic Table of the Elements (CAS version) in any oxidation state possible for the appropriate metal atom;

K is an uncharged mono- or bidentate ligand;

L is a mono- or dianionic ligand;

X is CR 1 or N;

Y is NR 2 or CR 2 2 ;

A, D, G, E, A′, D′, G′ and E′

are each independently CH, CR 3 or N;

R 1 is F, CN, C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, substituted or unsubstituted C 6 -C 30 -aryl or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

R 2 , R 3

are each independently substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 5 -C 20 -cycloalkyl, substituted or unsubstituted C 5 -C 20 -cycloalkenyl, substituted or unsubstituted heterocycloalkyl having from 5 to 30 ring atoms, substituted or unsubstituted heterocycloalkenyl having from 5 to 30 ring atoms, substituted or unsubstituted C 2 -C 20 -alkenyl, substituted or unsubstituted C 2 -C 20 -alkynyl, substituted or unsubstituted C 6 -C 30 -aryl, substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms or a substituent with donor or acceptor action selected from the group consisting of: C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, SiR 4 R 5 R 6 , halogen radicals, halogenated C 1 -C 20 -alkyl radicals, carbonyl (—CO(R 4 )), carbonylthio (—C═O(SR 4 )), carbonyloxy (—C═O(OR 4 )), oxycarbonyl (—OC═O(R 4 )), thiocarbonyl (—SC═O(R 4 )), amino (—NR 4 R 5 ), OH, pseudohalogen radicals, amido (—C═O(NR 4 R 5 )), —NR 4 C═O(R 5 ), phosphonate (—P(O)(OR 4 ) 2 ), phosphate (—OP(O)(OR 4 ) 2 ), phosphine (—PR 4 R 5 ), phosphine oxide (—P(O)R 4 2 ), sulfate (—OS(O) 2 OR 4 ), sulfoxide (—S(O)R 4 ), sulfonate (—S(O) 2 OR 4 ), sulfonyl (—S(O) 2 R 4 ), sulfonamide (—S(O) 2 NR 4 R 5 ), NO 2 , boronic esters (—B(OR 4 ) 2 ), imino (—C═NR 4 R 5 ), borane radicals, stannate radicals, hydrazine radicals, hydrazone radicals, oxime radicals, nitroso groups, diazo groups, vinyl groups, sulfoximines, alanes, germanes, boroxines and borazines;

or

two adjacent R 3 radicals together form a saturated or unsaturated, substituted or unsubstituted bridge comprising from 3 to 6 atoms, wherein the R 3 radicals together with one of the elements A=D, D-E, D′-E′, E′=G′ form a 5- to 8-membered ring;

or

the R 3 radicals at the G′ and A positions together form a saturated or unsaturated, substituted or unsubstituted bridge comprising from 1 to 4 atoms, wherein the R 3 radicals together with the element -G′-C—C-A- form a 5- to 8-membered ring;

R 4 , R 5 , R 6

are each independently H, substituted or unsubstituted C 1 -C 20 -alkyl or substituted or unsubstituted C 6 -C 30 -aryl or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

n is a number of carbene ligands, where n is at least 1 and the carbene ligands in the complex of the formula I, when n>1, are the same or different;

m is a number of ligands K, where m is 0 or ≧1, and the ligands K, when m>1, are the same or different;

o is a number of ligands L, where o is 0 or ≧1, and the ligands L, when o>1, are the same or different;

where the sum of n+m+o depends on the oxidation state and coordination number of the metal atom used and on the denticity of the ligands L and K, and also on the charge of the ligand L, with the condition that n is at least 1.

2. The carbene complex according to claim 1 , wherein

M is Ir(III),

n is 3, and

m, o are each 0.

3. The carbene complex according to claim 1 , wherein

R 2 , R 3

are each independently selected from the group consisting of substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 2 -C 20 -alkenyl, substituted or unsubstituted C 2 -C 20 -alkynyl, substituted or unsubstituted C 6 -C 30 -aryl, substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms, C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, SiR 4 R 5 R 6 , halogen radicals, halogenated C 1 -C 20 -alkyl radicals and pseudohalogen radicals;

or

two adjacent R 3 radicals together form a saturated or unsaturated, methyl-, methoxy-, phenyl-, SiMe 3 -, SiPh 3 -, F-, CF 3 - or CN-substituted or unsubstituted bridge comprising 3 or 4 carbon atoms, wherein the R 3 radicals together with one of the elements A=D, D-E, A′=D′, D′-E′, E′=G′ form a 5- or 6-membered ring;

or

the R 3 radicals at the G′ and A positions together form a saturated or unsaturated, methyl-, methoxy-, phenyl-, SiMe 3 -, SiPh 3 -, F—, CF 3 — or CN-substituted or unsubstituted bridge comprising 1 or 2 carbon atoms, wherein the R 3 radicals together with the element -G′-C—C-A- form a 5- or 6-membered ring.

4. The carbene complex according to claim 1 , wherein

R 2 is selected from the group consisting of substituted or unsubstituted C 1 -C 20 -alkyl which is branched in the 1-position, substituted or unsubstituted C 6 -aryl, and substituted or unsubstituted heteroaryl having from 5 to 13 ring atoms.

5. The carbene complex according to claim 1 , wherein

X is N, and

is NR 2 .

6. The carbene complex according to claim 1 , wherein

A, D, G, E, A′, D′, G′ and E′

are each CH or CR 3 .

7. The carbene complex according to claim 1 , wherein the carbene complex is selected from the group consisting of

in which:

A, D, G, E, A′, D′, G′ and E′

are each independently CH, CR 3 or N, preferably CH or CR 3 ;

R 2 , R 3 are each independently substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 5 -C 20 -cycloalkyl, substituted or unsubstituted C 5 -C 20 -cycloalkenyl, substituted or unsubstituted heterocycloalkyl having from 5 to 30 ring atoms, substituted or unsubstituted heterocycloalkenyl having from 5 to 30 ring atoms, substituted or unsubstituted C 2 -C 20 -alkenyl, substituted or unsubstituted C 2 -C 20 -alkynyl, substituted or unsubstituted C 6 -C 30 -aryl, substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms or a substituent with donor or acceptor action selected from the group consisting of: C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, SiR 4 R 5 R 6 , halogen radicals, halogenated C 1 -C 20 -alkyl radicals, carbonyl (—CO(R 4 )), carbonylthio (—C═O(SR 4 )), carbonyloxy (—C═O(OR 4 )), oxycarbonyl (—OC═O(R 4 )), thiocarbonyl (—SC═O(R 4 )), amino (—NR 4 R 5 ), OH, pseudohalogen radicals, amido (—C═O(NR 4 R 5 )), —NR 4 C═O(R 5 ), phosphonate (—P(O)(OR 4 ) 2 ), phosphate (—OP(O)(OR 4 ) 2 ), phosphine (—PR 4 R 5 ), phosphine oxide (—P(O)R 4 2 ), sulfate (—OS(O) 2 OR 4 ), sulfoxide (—S(O)R 4 ), sulfonate (—S(O) 2 OR 4 ), sulfonyl (—S(O) 2 R 4 ), sulfonamide (—S(O) 2 NR 4 R 5 ), NO 2 , boronic esters (—B(OR 4 ) 2 ), imino (—C═NR 4 R 5 ), borane radicals, stannate radicals, hydrazine radicals, hydrazone radicals, oxime radicals, nitroso groups, diazo groups, vinyl groups, sulfoximines, alanes, germanes, boroxines and borazines;

or

two adjacent R 3 radicals together form a saturated or unsaturated, substituted or unsubstituted bridge composed of from 3 to 6 atoms, wherein the R 3 radicals together with one of the elements A=D, D-E, A′=D′, D′-E′, E′=G′ form a 5- to 8-membered ring;

or

the R 3 radicals at the G′ and A positions together form a saturated or unsaturated, substituted or unsubstituted bridge composed of from 1 to 4 atoms, wherein the R 3 radicals together with the element -G′-C—C-A- form a 5- to 8-membered ring;

R 4 , R 5 , R 6

are each independently H, substituted or unsubstituted C 1 -C 20 -alkyl or substituted or unsubstituted C 6 -C 30 -aryl, or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

Y is CR 2 2 ;

M is Ir, Os or Pt;

K is an uncharged bidentate ligand;

L is a monoanionic bidentate ligand;

n is the number of carbene ligands, where n is 3 in the case of Ir, is 2 in the case of Os and is 1 or 2 in the case of Pt, and the carbene ligands in the complexes of the formulae Ia, Ib, Ic and Id are the same or different;

m is 0 in the case that M=Ir or Pt and is 1 in the case of Os;

o is 0 in the case that M=Ir or Os and Pt and in the case that n=2, and is 1 in the case of Pt and in the case that n=1.

8. A process for preparing a carbene complex according to claim 1 , comprising a reaction of at least one ligand precursor of the formula (III)

in which

Q is a monoanionic counterion;

X is CR 1 or N;

Y is NR 2 or CR 2 2 ;

A, D, G, E, A′, D′, G′ or E′

are each independently CH, CR 3 or N;

R 1 is F, CN, C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, substituted or unsubstituted C 6 -C 30 -aryl or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

R 2 , R 3

are each independently substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 5 -C 20 -cycloalkyl, substituted or unsubstituted C 5 -C 20 -cycloalkenyl, substituted or unsubstituted heterocycloalkyl having from 5 to 30 ring atoms, substituted or unsubstituted heterocycloalkenyl having from 5 to 30 ring atoms, substituted or unsubstituted C 2 -C 20 -alkenyl, substituted or unsubstituted C 2 -C 20 -alkynyl, substituted or unsubstituted C 6 -C 30 -aryl, substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms or a substituent with donor or acceptor action selected from the group consisting of: C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, SiR 4 R 5 R 6 , halogen radicals, halogenated C 1 -C 20 -alkyl radicals, carbonyl (—CO(R 4 )), carbonylthio (—C═O(SR 4 )), carbonyloxy (—C═O(OR 4 )), oxycarbonyl (—OC═O(R 4 )), thiocarbonyl (—SC═O(R 4 )), amino (—NR 4 R 5 ), OH, pseudohalogen radicals, amido (—C═O(NR 4 R 5 )), —NR 4 C═O(R 5 ), phosphonate (—P(O)(OR 4 ) 2 ), phosphate (—OP(O)(OR 4 ) 2 ), phosphine (—PR 4 R 5 ), phosphine oxide (—P(O)R 4 2 ), sulfate (—OS(O) 2 OR 4 ), sulfoxide (—S(O)R 4 ), sulfonate (—S(O) 2 OR 4 ), sulfonyl (—S(O) 2 R 4 ), sulfonamide (—S(O) 2 NR 4 R 5 ), NO 2 , boronic esters (—B(OR 4 ) 2 ), imino (—C═NR 4 R 5 ), borane radicals, stannate radicals, hydrazine radicals, hydrazone radicals, oxime radicals, nitroso groups, diazo groups, vinyl groups, sulfoximines, alanes, germanes, boroxines and borazines;

or

two adjacent R 3 radicals together form a saturated or unsaturated, substituted or unsubstituted bridge composed of from 3 to 6 atoms, wherein the R 3 radicals together with one of the elements A=D, D-E, A′=D′, D′-E′, E′=G′ form a 5- to 8-membered ring;

or

the R 3 radicals at the G′ and A positions together form a saturated or unsaturated, substituted or unsubstituted bridge composed of from 1 to 4 atoms, wherein the R 3 radicals together with the element -G′-C—C-A- form a 5- to 8-membered ring;

and

R 4 , R 5 , R 6

are each independently H, substituted or unsubstituted C 1 -C 20 -alkyl or substituted or unsubstituted C 6 -C 30 -aryl or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

with a metal complex comprising at least one metal M where

M is a metal atom selected from the group consisting of metals of group IB, IIB, IIIB, IVB, VB, VIIB, VIIB, VIIIB, the lanthanides and IIIA of the Periodic Table of the Elements (CAS version) in any oxidation state possible for the appropriate metal atom.

9. The process according to claim 8 , wherein the metal M used is Ir, Os or Pt.

10. An organic light-emitting diode comprising at least one carbene complex according to claim 1 .

11. A light-emitting layer comprising at least one carbene complex according to claim 1 .

12. An organic light-emitting diode comprising at least one light-emitting layer according to claim 11 .

13. A device selected from the group consisting of stationary visual display units, mobile visual display units, and illuminating means, comprising at least one organic light-emitting diode according to claim 12 .

14. A device selected from the group consisting of stationary visual display units, mobile visual display units and illuminating means, comprising at least one organic light-emitting diode according to claim 10 .

15. The carbene complex according to claim 1 , wherein M is Fe, Os, Co, Rh, Ir, Ni, Ru, Pd, Pt, Cu, Au, Ce, Tb, or Eu.

16. The carbene complex according to claim 3 , wherein R 3 is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, tolyl, dimethylphenyl, trimethylphenyl, pyridyl, thienyl, pyrrolyl, furyl, thiazolyl, oxazolyl, pyrazolyl, imidazolyl, methoxy, phenoxy, SCH 3 , SPh, SiR 4 R 5 R 6 , F, Cl, Br, CF 3 , and CN.

17. The carbene complex according to claim 1 , wherein L is a monoanionic ligand.

18. The carbene complex according to claim 1 , wherein X is N.

19. The carbene complex according to claim 4 , wherein R 2 is selected from the group consisting of isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, 2-tolyl, 2-methoxyphenyl, 2-cyanophenyl, 2-trifluoromethylphenyl, 2,6-difluorophenyl, 2,3-, 2,4-, 2,5- and 2,6-dimethylphenyl or 2,4,6-, 2,3,4- and 2,3,5-trimethylphenyl; pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, thiophen-2-yl, thiophen-3-yl, pyrrol-2-yl, pyrrol-3-yl, furan-2-yl, furan-3-yl, thiazol-2-yl, oxazol-2-yl, pyrazol-3-yl and imidazol-2-yl.