Structural investigation of iridium phenylpyridine complexes functionalized with fluorine and sulfonyl substituents

Recent studies on the synthesis, properties and structural characterization of some Ir complexes with arylpyridine ligands have attracted considerable interest in both academic and industrial fields due to their use as phosphorescent materials in light emitting diodes (PHOLEDs)[1]. One of the main advantages offered by this class of Ir complexes is the possibility to careful control their light emission colour by suitably choosing the kind and position of substituent groups[2]. Latest literature also shows that the stereochemistry of these complexes has a significant influence on their photophysical properties and performance in devices[3]. Therefore, structural studies of these materials are very important in order to identify univocally the atomic arrangement of the compounds under investigation. In a recent publication, we have synthesized and spectroscopically characterized a series of heteroleptic iridium complexes functionalized with benzylsulfonyl groups and fluorine atoms in different positions of 2-phenylpyridine ligands. Investigation of the stereochemistry of these complexes has been firstly carried out by 1H and 13C and NMR spectroscopy of their iridium dichloro-bridged dimer precursors. Here, we report the crystallographic characterization of the iridium dimers (PhSO2-F2ArPy)4Ir2Cl2 and (PhSO2-FArPy)4Ir2Cl2 which sheds light on their stereochemistry, as well as on the stereochemistry of the corresponding heteroleptic iridium complexes. The crystal structures were determined by SCXRD. Both complexes crystalize in P space group and have a trans configuration of the arylpyridine ligands. The geometry parameters and the atomic coordination around central Ir3+ ion are similar in both complexes, each one showing a regular octahedral arrangement of the donor atoms.