Transition-metal complexes, which are suitable as emitters for phosphorescent organic light- emitting diodes (PhOLED) are currently of great interest.[1] Especially iridium and platinum compounds with conjugated ligands are prominent examples because of their exceptional luminescence properties.[1, 2] Iridium complexes in most cases carry two or three cyclometalated bidentate ligands, either as homo-or heteroleptic complexes.[1, 2b] ...