Synthesis and characterization of a dipyridocatecholate silicon complex

The reaction of [Si(bpy)2I2]I2 with 1,10-phenanthroline-5,6-dione followed by metathesis provides various salts of [Si(bpy)2(dpcat)]+ 2 (1, bpy = 2,2′-bipyridine and dpcat = dipyridocatecholate). Recrystallization of [Si(bpy)2(dpcat)](ClO4)2 from an aqueous solution of NaClO4 afforded orange crystals of Na[Si(bpy)2(dpcatH)](ClO4)4·3H2O (2), in which silicon possesses a distorted octahedral geometry. The dipyridocatecholate ligand is coordinated to the silicon through the oxygen atoms, and one of the nitrogen atoms is protonated. 29Si NMR and ESI-mass spectroscopy indicate [Si(bpy)2(dpcat)]+ 2 maintains its hexacoordinate structure in solution. The complex is stable with respect to hydrolysis, and degassed aqueous solutions luminesce at 410 nm.