Previous studies have demonstrated hexacoordinate silicon pincer complexes to be attractive candidates for efficient electron and hole transport layers in organic electronic devices. This work expands the field by incorporating carbon-nitrogen-carbon (CNC) pincer ligands for the first time in hypercoordinate silicon complexes and explores the impact of the ligand on molecular and material properties of the complex. The dianionic 2,6-diphenylpyridine ligand (DPP) was selected for the CNC-pincer studies. 2,6-Di(bromophen-2-yl)pyridine (DPP) was used as a precursor forming the known intermediate dilithiodiphenylpyridine dianion. This dianion was then reacted with either silicon tetrachloride or dichlorodimethylsilane, forming the respective hypercoordinate silicon complex. For comparison, 2,6-bis(benzimidazol-2-yl)pyridine (bzimpy) was also reacted with dichlorodimethylsilane in the presence of triethylamine (TEA) to form the pentacoordinate complex Si(bzimpy)Me2.The resulting pentacoordinate complexes were not fully isolated nor implemented into devices due to high reactivity or instability of the Si(pincer)R2 complexes. The hexacoordinate Si(DPP)2 complex however was quite robust, showing resistance to hydrolysis in NMR solutions of 50:50 DMSO:H2O and displaying thermally stability to over 420 ℃ and a high Tg (263 ℃). CV data shows an oxidation wave and a reduction wave both of which were partially reversible (Eox,onset = +0.47 V and Ered,onset = -2.20 V vs. Fc+1/0), E(HOMO) = -5.27 V and E(LUMO) = -2.60 V and a band gap ΔELUMO-HOMO = 2.73 V. Devices were made to test charge mobilities of Si(DPP)2, the three best devices (hole only and electron only) were averaged for their respective mobilities in the space charge limited current regime resulting in an electron mobility of µe = 1.8×10-4 cm2/Vs and a hole mobility of µh = 1.1×10-5 cm2/Vs.
