A total of 21 complexes of CuX (X = Cl, Br, I) with bridging ligand (B = 4,4'-dipyridyl (Bpy), pyrazine (Pyz), quinoxaline (Quin), phenazine (Phz), 1,4-diazabicyclo[2.2.2]octane (DABCO), and hexamethylenetetramine (HMTA)) have been synthesized. The products show two stoichiometries: [CuXB] (type 1) and [(CuX)2B] (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)2B(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 of B, L, or both. The X-ray structures of [(CuBrL)2(Bpy)] and [(CuBrL)2(Pyz)] (type 3) reveal 1D chains formed from rhomboidal (LCu)2Br2 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.

Coordination Polymers of Copper(I) Halides

Homoatomare d10‐d10‐Wechselwirkungen — Auswirkungen auf Struktur‐ und Stoffeigenschaften

Coordination and organometallic compounds and inorganic–organic hybrid crystalline materials for second-order non-linear optics

The mode of co-ordination of the multidentate ligand 2,2′-dimethyl-4,4′-bipyrimidine (L) was found to depend on the metal ion, the crystallization conditions, the metal-to-ligand ratio, and the anion. With nickel a chelating co-ordination through the endo-dentate nitrogen donor set is observed in the molecular complex [NiCl2(L)(H2O)]·CH3NO2, derived from hot CH3NO2. With Cu(NO3)2 and CuI–CH3CN one- and two-dimensional (1-D and 2-D) co-ordination polymers of formula ∞ 1[Cu(NO3)2(µ-L)] and ∞ 2[Cu2(µ3-I)2(µ-L)] are obtained, where the bipyrimidine ligand is solely bridging through the two exo-dentate nitrogen atoms. On the other hand, a synthesis from CuI and crystallization from hot dimethyl sulfoxide leads to a 1-D iodide-bridged co-ordination polymer ∞ 1[Cu(µ-I)(L)] with a chelating ligand. With AgNO3 two different types of co-ordination polymers were found, depending on the silver-to-ligand ratio. At a 1∶1 ratio in the presence of a co-ordinating anion a 2-D network, ∞ 2[Ag(µ-NO3)2(µ-L)], with only bridging bipyrimidine ligands is observed. At a metal excess, a 3-D framework, ∞ 3[Ag3(µ3-NO3)3(µ3-L)2], forms where L functions both as a chelating and as bridging ligand. A tetradentate co-ordination mode of L towards silver is also found with non-co-ordinating anions, such as BF4– and PF6–, and gives rise to the isostructural 2-D co-ordination polymers of formula ∞ 2[Ag3(CH3CN)3(µ3-L)2]X3 (X = BF4 or PF6).

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Co-ordination engineering: when can one speak of an “understanding”? Case study of the multidentate ligand 2,2′-dimethyl-4,4′-bipyrimidine†

The formation of co-ordination polymers between copper(I) halides and 1,3,5-triazine (tri), a potentially tridentate N-donor bridging ligand with threefold symmetry, has been studied. Complexes with both 3∶1 and 2∶1 molar ratios are formed by both CuBr and CuI. The compounds [Cu3X3(tri)]∞ (X = Br or I) are structurally similar, despite crystallising in different space groups. They are composed of (CuX)∞ columns linked by triazine molecules to generate three-dimensional constructions with non-crystallographically imposed threefold symmetry. The (CuX)∞ columnar motif can be described as a series of perpendicularly stacked Cu3X3 chairs, alternately rotated by 60° and linked by Cu–X contacts. The tetrahedral co-ordination geometry of the copper centres is completed by a tridentate triazine bridge which links two copper atoms in separate columns. Thus, each (CuX)∞ column is linked to six adjacent (CuX)∞ columns. The structure of [Cu2Br2(tri)]∞ comprises (CuBr)∞ columns and castellated (CuBr)∞ chains linked by triazine molecules to generate a construction with crystallographically imposed threefold symmetry. The (CuBr)∞ columns are similar to but more regular than those found in [Cu3Br3(tri)]∞. In this case, however, each column is linked to six adjacent chains. The (CuBr)∞ castellated chain motif is very unusual. The tetrahedral copper centres are co-ordinated by two adjacent bromide anions and by two triazine molecules each of which links a second chain and a column. Consequently, each chain is linked to four neighbouring chains and two neighbouring columns. Despite a stoichiometry identical to that of [Cu2Br2(tri)]∞, [Cu2I2(tri)]∞ has a completely different structure. The triazine molecules act as bidentate bridging ligands to link (CuI)∞ layers thereby giving alternating inorganic and organic layers. The tetrahedral co-ordination geometry of the copper centres in the (CuI)∞ layers, which are effectively undulating hexagonal nets, is provided by three iodide anions from the layers and by a bridging triazine molecule.

Controlling copper(I) halide framework formation using N-donor bridging ligand symmetry: use of 1,3,5-triazine to construct architectures with threefold symmetry

The crystal structures of 1 : 1 adducts of cuprous iodide with collidine ICu(col) and 2,6-lutidine ICu(lut), and of cuprous chloride with pyridine ClCu(py), have been determined at 295 K and refined by full-matrix least squares to residuals of 0.052 [ICu(col)], 0.079 [ICu(lut)], 0.057 [ClCu(py)] for 465, 1761 and 720 ?observed? reflections respectively. Crystal data.-ICu(col), orthorhombic, P21mn, a 11.500(3), b 10.620(3), c 4.159(1) Ǻ, Z 2. ICu(lut), monoclinic, P21/c, a 16.377(9), b 7.833(3), c 15.401(8) Ǻ, β 110.53(4)°, Z 8. ClCu(py), monoclinic, P21, a 9.324(4), b 3.8484(7), c 8.663(4) Ǻ, β 107.08(3)°, Z 2. The 1 : 1 cuprous bromide-pyridine adduct BrCu(py) is isomorphous with ClCu(py): a 9.423(2), b 3.9585(6), c 8.907(2) Ǻ, β 108.13(2)°. In none of the three structures is the tetrameric (CuXL)4 species found. The structure of ICu(col) is an infinite zig-zag I-Cu-I-Cu- polymer running parallel to c; the copper is also coordinated by the collidine, Cu, I and N lying in the mirror y = 0.5 which also bisects the collidine ring. The structure of ICu(lut) comprises dimeric species, a pair of three-coordinated copper atoms being bridged by the two associated iodines. ClCu(py) has the ?ribbon? structure typified by CuCl,MeCN and CuBr,MeCN, an infinite polymer parallel to b. The inability of ICu(col) and ICu(lut) to form tetramers is attributed to steric hindrance of the methyl substituents of the base. The Cu-Cu distance in ICu(lut) is remarkably short (2.586 Ǻ).

James A. Campbell

Papers

Structural studies in the 1:1 copper(I) halide-pyridine base system