Carbene metal complexes as OLED materials

1. A [carbene] m M-(X—Y) n compound, wherein the [carbene] ligand is of formula

wherein

Ring D is an aromatic cyclic ring or a fused aromatic cyclic ring;

Z 1 is selected from a bond, O, or S;

A 1 and A 2 can be C or N;

R 1 and R 2 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, CN, CF 3 , NR′ 2 , NO 2 , OR′, SR′, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group; or alternatively, two adjacent R 1 or R 2 groups on the same or adjacent ring, together form independently a 5 or 6-member cyclic group, wherein the cyclic group is selected from cycloalkyl, cycloheteroalkyl, or heteroaryl; and wherein said cyclic group is optionally substituted by one or more substituents J, wherein each substituent J is independently selected from the group consisting of R′, CN, CF 3 , NR′ 2 , NO 2 , OR′, and SR′, or alternatively, two J groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group;

each R′ is independently selected from the group consisting of halo, H, alkyl, alkenyl, alkynyl, heteroalkyl, aralkyl, aryl, and heteroaryl;

R 3 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group;

a is 0, 1, 2, 3, or 4; c is 0, 1, or 2;

(X-Y) is selected from a photoactive ligand or an ancillary ligand; and

m is a value from 1 to a maximum number of ligands that can be attached to the metal M; and m+n is the maximum number of ligands that can be attached to the metal M.

2. The compound of claim 1 selected from the group consisting of

wherein

R 1 , R 2 , and R 4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, CN, CF 3 , NR′ 2 , NO 2 , OR′, SR′, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group; or alternatively, two adjacent R 1 or R 2 groups on the same or adjacent ring, together form independently a 5 or 6-member cyclic group, wherein the cyclic group is selected from cycloalkyl, cycloheteroalkyl, or heteroaryl; and wherein said cyclic group is optionally substituted by one or more substituents J, wherein each substituent J is independently selected from the group consisting of R′, CN, CF 3 , NR′ 2 , NO 2 , OR′, and SR′, or alternatively, two J groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group;

each R′ is independently selected from the group consisting of halo, H, alkyl, alkenyl, alkynyl, heteroalkyl, aralkyl, aryl, and heteroaryl;

R 3 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group;

a is 0, 1, 2, 3, or 4; b is 0, 1, 2, or 3; c is 0, 1, or 2;

(X-Y) is selected from a photoactive ligand or an ancillary ligand; and

m is a value from 1 to a maximum number of ligands that can be attached to the metal M;

and m+n is the maximum number of ligands that can be attached to the metal M.

3. The compound of claim 1 , wherein the two adjacent R 1 groups together form the cyclic group selected from cycloalkyl, cycloheteroalkyl, or heteroaryl; wherein the cyclic group is optionally substituted by one or more substituents J.

4. The compound of claim 1 , wherein the two adjacent R 1 groups together form the heteroaryl group; wherein the heteroaryl group is optionally substituted by one or more substituents J.

5. The compound of claim 4 , wherein the heteroaryl group formed by the two adjacent R 1 groups is selected from the group consisting of pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyridine, pyrazine, and pyrimidine, each of which is optionally substituted by one or more substituents J.

6. An organic light emitting device that includes an anode, a cathode, and an organic layer disposed between the anode and cathode, wherein the organic layer includes a

[carbene] m M-(X—Y) n compound, wherein the [carbene] ligand is of formula

wherein

Ring D is an aromatic cyclic ring or a fused aromatic cyclic ring;

Z 1 is selected from a bond, O, or S;

A 1 and A 2 can be C or N;

R 1 and R 2 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, CN, CF 3 , NR′ 2 , NO 2 , OR′, SR′, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group; or alternatively, two adjacent R 1 or R 2 groups on the same or adjacent ring, together form independently a 5 or 6-member cyclic group, wherein the cyclic group is selected from cycloalkyl, cycloheteroalkyl, or heteroaryl; and wherein said cyclic group is optionally substituted by one or more substituents J, wherein each substituent J is independently selected from the group consisting of R′, CN, CF 3 , NR′ 2 , NO 2 , OR′, and SR′, or alternatively, two J groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group;

each R′ is independently selected from the group consisting of halo, H, alkyl, alkenyl, alkynyl, heteroalkyl, aralkyl, aryl, and heteroaryl;

R 3 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group;

a is 0, 1, 2, 3, or 4; c is 0, 1, or 2;

(X—Y) is selected from a photoactive ligand or an ancillary ligand; and

m is a value from 1 to a maximum number of ligands that can be attached to the metal M; and m+n is the maximum number of ligands that can be attached to the metal M.

7. The device of claim 6 , wherein the two adjacent R 1 groups together form the heteroaryl group; wherein the heteroaryl group is optionally substituted by one or more substituents J.

8. A consumer product comprising the device of claim 6 , wherein the consumer product is selected from the group consisting of flat panel displays, computer monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, vehicles, theater or stadium screen, and a sign.

9. The device of claim 6 wherein the [carbene] m M-(X—Y) n compound is selected from the group consisting of

wherein

R 1 , R 2 , and R 4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, CN, CF 3 , NR′ 2 , NO 2 , OR′, SR′, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group; or alternatively, two adjacent R 1 or R 2 groups on the same or adjacent ring, together form independently a 5 or 6-member cyclic group, wherein the cyclic group is selected from cycloalkyl, cycloheteroalkyl, or heteroaryl; and wherein said cyclic group is optionally substituted by one or more substituents J, wherein each substituent J is independently selected from the group consisting of R′, CN, CF 3 , NR′ 2 , NO 2 , OR′, and SR′, or alternatively, two J groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group;

each R′ is independently selected from the group consisting of halo, H, alkyl, alkenyl, alkynyl, heteroalkyl, aralkyl, aryl, and heteroaryl;

R 3 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aralkyl, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group;

a is 0, 1, 2, 3, or 4; b is 0, 1, 2, or 3; c is 0, 1, or 2;

(X—Y) is selected from a photoactive ligand or an ancillary ligand; and

m is a value from 1 to a maximum number of ligands that can be attached to the metal M; and m+n is the maximum number of ligands that can be attached to the metal M.

10. The device of claim 9 , wherein the two adjacent R 1 groups together form the heteroaryl group; wherein the heteroaryl group is optionally substituted by one or more substituents J.

11. The compound of claim 1 , wherein Ring D is an aromatic cyclic ring; Z 1 is a bond; and both A 1 and A 2 are C.

12. The compound of claim 11 , wherein R 1 and R 2 are independently selected from the group consisting of hydrogen, alkyl, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl, and a heterocyclic group; or alternatively, two adjacent R 1 or R 2 groups on the same or adjacent ring, together form independently a 5 or 6-member cyclic group, wherein the cyclic group is selected from cycloalkyl, cycloheteroalkyl, or heteroaryl.