화학공학소재연구정보센터
Inorganic Chemistry, Vol.50, No.17, 8465-8476, 2011
Modulation of Metal-Metal Separations in a Series of Ag(I) and Intensely Blue Photoluminescent Cu(I) NHC-Bridged Triangular Clusters
A series of picolyl-substituted NHC-bridged triangular complexes of Ag(I) and Cu(I) were synthesized upon reaction of the corresponding ligand precursors, [Him(CH(2)py)(2)]BF4 (1a), [Him(CH(2)py-3,4-(OMe)(2))(2)]BF4 (1b), [Him(CH(2)py-3,5-Me-2-4-OMe)(2)]BF4 (1c), [Him(CH(2)py-6-COOMe)(2)]BF4 (1d), and [H(S)im(CH(2)py)(2)]-BF4 (1e), with Ag2O and Cu2O, respectively. Complexes [Cu-3(im(CH(2)py)(2))(3)](BF4)(3) (2a), [Cu-3(im(CH(2)py-3,4-(OMe)(2))(2))(3)](BF4)(3) (2b), [Cu-3(im(CH(2)py-3,5-Me-2-4-OMe)(2))(3)](BF4)(3), (2c), [Ag-3(im(CH(2)py-3,4-(OMe)(2))(2))(3)](BF4)(3), (3b), [Ag-3(im(CH(2)py-3,5-Me-2-4-OMe)(2))(3)](BF4)(3) (3c), [Ag-3(im(CH(2)py-6-COOMe)(2))(3)](BF4)(3) (3d), and [Ag-3((S)im(CH(2)py)(2))(3)](BF4)(3) (3e) were easily prepared by this method. Complex 2e, [Cu-3((S)im(CH(2)py)(2))(3)](BF4)(3), was synthesized by a carbene-transfer reaction of 3e, [Ag-3((S)im(CH(2)py)(2))(3)](BF4)(3), with CuCl in acetonitrile. The ligand precursor Id did not react with Cu2O. All complexes were fully characterized by NMR, UV-vis, and luminescence spectroscopies and high-resolution mass spectrometry. Complexes 2a-2c, 2e, and 3b-3e were additionally characterized by single-crystal X-ray diffraction. Each metal complex contains a nearly equilateral triangular M-3 core wrapped by three bridging NHC ligands. In 2a-2c and 2e, the Cu-Cu separations are short and range from 2.4907 to 2.5150 angstrom. In the corresponding Ag(I) system, the metal-metal separations range from 2.7226 to 2.8624 angstrom. The Cu(I)-containing species are intensely blue photoluminescent at room temperature both in solution and in the solid state. Upon UV excitation in CH3CN, complexes 2a-2c and 2e emit at 459, 427, 429, and 441 nm, whereas in the solid state, these bands move to 433, 429, 432, and 440 nm, respectively. As demonstrated by H-1 NMR spectroscopy, complexes 3b-3e are dynamic in solution and undergo a ligand dissociation process. Complexes 3b-3e are weakly photoemissive in the solid state.