Dinuclear Cu(I) complexes of 1,2,4,5-tetra(7-azaindolyl)benzene: persistent 3-coordinate geometry, luminescence, and reactivity.
Five Cu(I) complexes [Cu2(ttab)(CH3CN)2][BF4]2 (1), [Cu(2)(ttab)(PPh3)2][BF4]2 (2), [Cu2(ttab)I2] (3), [Cu2(ttab)(I3)2] (4), and [Cu2(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 Cu2 compounds while compound 5 is a 1D coordination polymer with the I- ligand bridging two dinuclear Cu2 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 CH2Cl2 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 O2 gas, as established by UV-vis spectra, but the oxidized products have not been characterized.
Zhao
Shu-Bin
SB
Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Wang
Rui-Yao
RY
Wang
Suning
S
D001372:Aza Compounds / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008956:Models, Chemical; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry; D010618:Phenanthrolines / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014050:Toluene / Q000737:chemistry; D014961:X-Ray Diffraction
C520317:1,2,4,5-tetra(7-azaindolyl)benzene; D001372:Aza Compounds; D001965:Bromides; D007211:Indoles; D008024:Ligands; D010618:Phenanthrolines; D014050:Toluene; D003300:Copper; D001554:Benzene; D010100:Oxygen; C025205:1,10-phenanthroline