화학공학소재연구정보센터
Inorganic Chemistry, Vol.45, No.15, 5830-5840, 2006
Dinuclear Cu(I) complexes of 1,2,4,5-tetra(7-azaindolyl)benzene: Persistent 3-coordinate geometry, luminescence, and reactivity
Five Cu(I) complexes [Cu-2(ttab)(CH3CN)(2)][BF4](2) (1), [Cu-2(ttab)(PPh3)(2)][BF4](2) (2), [Cu-2(ttab)I-2] (3), [Cu-2(ttab)(I-3)(2)] (4), and [Cu-2(ttab)(I)BF4](n) (5) with 1,2,4,5-tetra(7-azaindolyl) benzene (ttab) have been synthesized and characterized. The structures of compound 1, 2, 4, and 5 have been determined by single-crystal X-ray diffraction analyses, which established that 1, 2, and 4 are discrete dinuclear Cu-2 compounds while compound 5 is a 1D coordination polymer with the I- ligand bridging two dinuclear Cu-2 units. The ttab ligand in all four complexes adopts a 1,3-chelation mode. The Cu( I) center in all complexes is three-coordinate. Close contact between the Cu( I) center and the benzene ring in the ttab ligand was observed in all four structures, which is believed to play a role in stabilizing the three-coordinate geometry of the Cu( I) center. The crystals of 1, 2, and 5 contain channels in the lattice that host solvent molecules such as CH2CI2 and toluene. Fluorescent measurements established that, in solution, compounds 1-3 display weak blue luminescence which originates from the ttab but is significantly red-shifted and has a much lower emission intensity, compared to the free ttab ligand. The application of compound 1 in C-N cross-coupling reactions was examined by using the reaction of phenyl halides with imidazole as a model system. For the reaction with phenyl iodide, 1 was found to be as effective a catalyst as the CuI/1,10-phenanthroline system. For the reaction with phenyl bromide, 1 is less effective than the CuI/1,10-phenanthroline system. Compound 1 reacts with O-2 gas, as established by UV-vis spectra, but the oxidized products have not been characterized.