| Abstract
| - We have developed selective low-temperature syntheses of fac and mer tris-cyclometalated Ir(III) complexes. The complexes of the general formula fac-Ir(C∧N)3 for C∧N = 2,2‘-thienylpyridine (thpy) and 2-phenylpyridine (ppy) were synthesized at 100 °C in o-dichlorobenzene from the corresponding [Ir(C∧N)2(NCCH3)2]PF6 complexes, while the mer-Ir(C∧N)3 complexes were synthesized under the same conditions from the corresponding [Ir(C∧N)2(OH)]2 dimers. A mechanism is proposed that may account for the selectivity observed in the formation of the mer-Ir(C∧N)3 and fac-Ir(C∧N)3 isomers in previous studies and the studies presented here.
- We have developed a selective low-temperature synthesis of fac and mer tris-cyclometalated Ir(III) complexes. Thechloro-bridged dimers [Ir(C∧N)2Cl]2 (C∧N = cyclometalating ligand) are cleaved in coordinating solvents like acetonitrileto give neutral Ir(C∧N)2(NCCH3)Cl species which in turn are reacted with AgPF6 to give hexafluorophosphate saltsof the bis-acetonitrile species [Ir(C∧N)2(NCCH3)2]PF6 for C∧N = 2,2‘-thienylpyridine (thpy) and 2-phenylpyridine(ppy). These bis-acetonitrile complexes are excellent starting materials for the synthesis of tris-Ir(III) complexes.The complexes of the general formula fac-Ir(C∧N)3 were synthesized with the ligands thpy and ppy at 100 °C ino-dichlorobenzene from the corresponding [Ir(C∧N)2(NCCH3)2]PF6 complexes. The reaction of [Ir(C∧N)2(NCCH3)2]PF6 with thpy at room temperature did not give the expected tris complex but instead gave [Ir(thpy)2(N,S-thpy)]PF6,with the third chelating ligand complexed through the sulfur atom of the thiophene ring. [Ir(thpy)2Cl]2, [Ir(ppy)2Cl]2,Ir(thpy)2(NCCH3)Cl, [Ir(thpy)2(NCCH3)2]PF6, [Ir(ppy)2(NCCH3)2]PF6, and [Ir(thpy)2(N,S-thpy)]PF6 were structurallycharacterized by X-ray crystallography. Additionally, hydroxy-bridged dimers, [Ir(C∧N)2(OH)]2, were synthesized asstarting materials for the selective synthesis of mer-Ir(C∧N)3 complexes at 100 °C in o-dichlorobenzene. A mechanismis proposed that may account for the selectivity observed in the formation of the mer-Ir(C∧N)3 and fac-Ir(C∧N)3isomers in previous studies and the studies presented here.
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