Coordination polymers of copper(I) halides

A total of 21 complexes of CuX (X = Cl, Br, I) with bridging Ligand (B = 4,4'-dipyridyl (Bpy), pyrazine (Pyz), quinoxaline (Quin), phenazine (Phi), 1,4-diazabicyclo[2.2.2]octane (DABCO), and hexamethylenetetramine (HMTA)) have been synthesized. The products show two stoichiometries: [CuXB] (type 1) and [(CuX)(2)B] (type 2). Both types can be obtained for B = Bpy, depending on the conditions of preparation. In these cases, the type 2 stoichiometry is the kinetic product. Type 2 complexes only are found for B = Pyz (X = I), Quin, Phz, DABCO, and HMTA. Type 1 complexes form for Pyz (X = Cl, Br). Thermogravimetic analyses of-the complexes reveal the general decomposition trend: 1 -> 2 -> [(CuX)(2)B-1/2] -> CUX. The X-ray crystal structure of [CuBr(Pyz)] (type 1) features copper atoms bridged by Br and Pyz, forming 2D sheets of fused rectangular Cu4Br2(Pyz)(2) units. The X-ray structure of [(CuI)(2)(Quin)] (type 2) shows 2D layers composed of [CU2I2](infinity) "stair step" chains which are cross-linked by Quin ligands. A total of 16 complexes of CuXL (L = P(OPh)(3)) with bridging ligand (B = those above and 1,4-dimethylpiperazine (DMP)) have also been prepared. All of these products, except those of HMTA, are of type 3 formulation, [(CuXL)2B]. The HMTA products have the formula [CuX(HMTA)], type 4. Thermal decomposition of the type 3 and 4 complexes occurs with;initial loss off, L, or both. The X-ray structures of [(CuBrL)(2)(Bpy)] and [(CuBrL)(2)(Pyz)] (type 3) reveal 1D chains formed from rhomboidal (LCu)(2)Br-2 units linked by the B ligand. The type 4 structure of [CuBrL(HMTA)] is shown by X-ray to be a simple halide-bridged dimer.