Phosphorescent materials

1. A compound comprising a ligand L having the structure:

wherein B and C are each independently a 5 or 6-membered carbocyclic or heterocyclic ring;

wherein A-B represents a bonded pair of carbocyclic or heterocyclic rings coordinated to a metal M via a nitrogen atom in ring A and an sp 2 hybridized atom in ring B;

wherein A-C represents a bonded pair of carbocyclic or heterocyclic rings;

wherein R a , R b , and R c may represent mono, di, tri, or tetra substitutions;

wherein R a , R b , and R c are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl;

wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , X 8 , and X 9 are independently selected from carbon and nitrogen;

wherein R 1 and R 2 are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl; and

wherein at least one of R 1 , R 2 , and the R a substituents adjacent to C is not hydrogen; and

wherein the ligand L is coordinated to a metal M having an atomic number greater than 40.

2. The compound of claim 1 , wherein the compound has the structure:

wherein m is the oxidation state of the metal M;

wherein n is at least 1; and

wherein L′ is a monoanionic bidentate ligand.

3. The compound of claim 1 , wherein the metal M is Ir.

4. The compound of claim 1 , wherein the compound is selected from the group consisting of:

wherein at least one of R 1 , R 2 , R 3 , and R 4 are not hydrogen; and

wherein R 5 is selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl.

5. The compound of claim 2 , wherein the compound is selected from the group consisting of:

6. The compound of claim 1 , wherein the compound is homoleptic.

7. The compound of claim 1 , wherein the compound is heteroleptic.

8. The compound of claim 2 , wherein L′ is selected from the group consisting of:

wherein R 1 ′, R 2 ′ and R 3 ′ are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl.

9. An organic light emitting device, comprising:

an anode:

a cathode; and

an organic layer, disposed between the anode and the cathode, the organic layer further comprising a compound having the formula:

wherein B and C are each independently a 5 or 6-membered carbocyclic or heterocyclic ring;

wherein A-B represents a bonded pair of carbocyclic or heterocyclic rings coordinated to the metal M via a nitrogen atom in ring A and an sp 2 hybridized atom in ring B;

wherein A-C represents a bonded pair of carbocyclic or heterocyclic rings;

wherein R a , R b , and R c may represent mono, di, tri, or tetra substitutions;

wherein R a , R b , and R c are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl;

wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , X 8 , and X 9 are independently selected from carbon and nitrogen;

wherein R 1 and R 2 are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl; and

wherein at least one of R 1 , R 2 , and the R a substituents adjacent to C is not hydrogen; and

wherein the ligand L is coordinated to a metal having an atomic number greater than 40.

10. The device of claim 9 , wherein the compound has the structure:

wherein m is the oxidation state of the metal M;

wherein n is at least 1;

wherein L′ is a monoanionic bidentate ligand.

11. The device of claim 9 , wherein the metal M is Ir.

12. The device of claim 9 , wherein the compound is selected from the group consisting of:

wherein at least one of R 1 , R 2 , R 3 , and R 4 are not hydrogen; and

wherein R 5 is selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylkyl, aryl, and heteroaryl.

13. The device of claim 9 , wherein the compound is selected from the group consisting of:

14. The device of claim 9 , wherein the organic layer is an emissive layer and the compound having the formula of Formula I is an emitting dopant.

15. The device of claim 14 , wherein the organic layer further comprises a host.

16. A heteroleptic compound selected from the group consisting of:

17. The compound of claim 16 , wherein the compound is

18. An organic light emitting device, comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, the organic layer further comprising a compound selected from the group consisting of:

19. A method for making heteroleptic compounds, comprising:

reacting

with

to form

wherein S is a neutral ligand;

wherein X is a counterion;

wherein A and B are each independently a 5 or 6-membered aromatic or heteroaromatic ring, and A-B represents a bonded pair of aromatic or heteroaromatic rings coordinated to the iridium via a nitrogen atom on ring A and an sp 2 hybridized carbon atom on ring B;

wherein C and D are each independently a 5 or 6-membered aromatic or heteroaromatic ring, and C-D represents a bonded pair of aromatic or heteroaromatic rings coordinated to the iridium via a nitrogen ring atom on ring C and an sp 2 hybridized carbon atom on ring D;

wherein R A , R B , R C , and R D are each independently selected from the group consisting of no substitution, alkyl, heteroalkyl, aryl, or heteroaryl groups;

wherein each of R A , R B , R C , and R D represent one or more substituents; and

wherein R Z is not H.

20. A heteroleptic complex having the formula Ir(L A-B ) 2 (L C-D ),

wherein L A-B is

wherein L C-D is selected from the group consisting of

and

wherein R 1 , R 2 , R 3 , R 4 and R 5 are each independently selected from the group consisting of hydrogen and alkyl; and

wherein each of R 1 , R 2 , R 3 , R 4 and R 5 may represent mono, di, tri, tetra, or penta substitutions.