Facial tris-cyclometallated group 9 complex synthesis

1. A process for forming a facial tris-cyclometallated rhodium or iridium complex isomer from a meridional isomer comprising subjecting the meridional isomer to an isomerization reaction in the presence of an acid, an organic solvent, and silica particles.

2. The process of claim 1 wherein the tris-cyclometallated complex is represented by one of the following formulas:

ML 3   (1)

M(L′) 2 L″  (2)

ML′L″L′″  (3)

wherein M is the metal Ir or Rh, L, L′, L″, and L′″ are monoanionic bidentate ligands that can be coordinated to M through a carbon and a heteroatom donor.

3. The process of claim 2 wherein at least one ligand includes an aromatic ring and a heterocyclic ring.

4. The process of claim 3 wherein the heterocyclic ring includes a nitrogen atom for coordinating to the metal complex.

5. The process of claim 4 wherein the ligand includes one derived from the substituted or unsubstituted forms of the following:

6. The process of claim 1 wherein the meridional tris-cyclometallated complex is an iridium complex that contains tree identical ligands.

7. The process of claim 1 wherein the meridional tris-cyclometallated complex is an iridium complex that contains two or three different ligands.

8. The process of claim 7 wherein at least one of the ligands is a 1-phenylisoquinoline or a 3-phenylisoquinoline group.

9. The process of claim 8 wherein at least one of the ligands is a 1-phenylisoquinoline represented by the formula:

wherein R 1 -R 10 represent hydrogen or independently selected substituents.

10. The process of claim 8 wherein at least one of the ligands is a 3-phenylisoquinoline represented by the formula:

wherein R 11 -R 20 represent hydrogen or independently selected substituents.

11. The process of claim 9 wherein two of the ligands are 1-phenylisoquinoline ligands and the other is a phenylpyridine group.

12. The process of claim 11 wherein the phenylpyridine ligand group is one selected from the substituted or unsubstituted forms of the following groups:

13. The process of claim 1 wherein the organic solvent comprises a halogenated hydrocarbon.

14. The process of claim 13 wherein the solvent comprises an alkyl halide.

15. The process of claim 13 wherein the solvent comprises methylene chloride or 1,2-dichloroethane.

16. The process of claim 1 wherein the acid is an organic acid.

17. The process of claim 16 wherein the organic acid is represented by the formula RCOOH wherein R is a 1-8 carbon alkyl group or an aryl group.

18. The process of claim 16 wherein the organic acid comprises acetic acid, propionic acid, butyric acid, benzoic acid, oxalic acid, malonic acid, or malic acid.

19. The process of claim 18 wherein the acid comprises acetic acid.

20. The process of claim 1 wherein the acid is an inorganic acid.

21. The process of claim 20 wherein the inorganic acid is hydrochloric acid.

22. The process of claim 1 wherein the acid is a Brönsted acid.

23. The process of claim 1 wherein the acid is a Lewis acid.

24. The process of claim 1 wherein the silica particle is silica gel.

25. The process of claim 24 wherein the size of the silica gel particle is larger than 60 mesh.

26. The process of claim 24 wherein the size of silica gel is smaller than 400 mesh.

27. The process of claim 24 wherein the size of the silica gel particles is between 60 and 400 mesh.

28. The process of claim 1 wherein the reaction is carried out for a period of time sufficient to form the facial isomer in >95% isomeric purity.

29. The process of claim 1 wherein the reaction is carried out for a period of time sufficient to form the facial isomer in >98% isomeric purity.

30. The process of claim 1 wherein the reaction product is further purified by sublimation or recrystallization.