John D. Kildea

Lewis-base adducts of group 11 metal(I) compounds. LIX. Crystal structure determinations of tetrakis(trimethylphosphine)copper(I) halides and tetrakis(triphenylphosphine)-copper(I) and -silver(I) hexafluorophosphates.

The crystal structures of [Cu(Pme3)4]X (X = Cl , Br, I) and of [M(PPh3)4] [PF6] (M = Cu, Ag) have been determined by single-crystal X-ray diffraction methods at 295 K. The former compounds contain nearly tetrahedral [Cu(PMe3)4]+ ions on sites of m symmetry with mean Cu-P bond lengths of 2.270, 2.271 and 2.278 Ǻ for X = Cl , Br and I respectively. The latter compounds contain [M(PPh3)4]+ ions on sites of 3 symmetry. In the M =Ag complex the coordination environment is close to tetrahedral, but in the M =Cu complex the length of the axial Cu-P bond [2.465(2)Ǻ] is significantly shorter than that of the off-axis bonds [2.566(2)Ǻ]. Possible reasons for this are discussed.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLII : [Cu4X4L4] 'cubane' clusters, L = hindered N-base ligand: synthesis and structures of the L = 2-(diphenymethyl)pyridine complexes (X = Cl, Br, I)

The synthesis and single-crystal X-ray structure characterization of tetrameric cubane clusters of copper(1) halides with the hindered N-base ligand 2-(diphenylmethy1)pyridine are reported. The chloride, bromide and iodide structures are isomorphous , crystallizing in the tetragonal space group 141/a, a ≈ 23, c ≈ 12 A , Z = 4 tetramers, the tetramer having crystallographically imposed 4 symmetry, well removed from the ideal 43m. In terms of each X3CuN fragment of the core, this distortion results in one of the N-Cu-X angles being enlarged by c. 30o with respect to the other two and one Cu-X bond distance shortened. Cu-N is also shorter than is usual in a four-coordinate environment and the cluster can be envisaged as being constructed from four quasi-linear monomers. The distortions may be attributed to interaction between the 6- and 2-α-substituent-hydrogen atoms and the halide atoms of the core. The effect diminishes with increasing halide size and increasing volume of the Cu4X4 core.

Far infrared spectroscopy of complexes of copper(I) halides with phosphine and amine ligands

Abstract Far i.r. spectra are reported for 34 adducts of phosphine and amine bases with copper (I) halides in which the copper atom is coordinated to only one terminal halide. CuX stretching frequencies are assigned for all of the chloro complexes and for most of the bromo and iodo complexes. The CuX stretching frequencies have been found to depend primarily on the CuX bond length, and appear to be relatively independent of the nature of the coordinating ligands. Best fit curves to the experimental data correspond to a dependence of ν(CuX) on the inverse nth power of r(CuX), where n is approximately equal to 5. Metal—halogen bond stretching force constants have been calculated for copper(I) and related silver(I) and gold(I) halide complexes assuming that the MX entity behaves as an uncoupled diatomic molecule. The results show that for three-coordinate copper(I) the force constants decrease in the order CuCl>CuBr>CuI and that the same trend is shown for four-coordinate copper(I) complexes, but the differences are considerably smaller than for the three-coordinate case. Analogous trends are found for the two- and three-coordinate gold compounds.

Lewis-base adducts of group 11 metal(I) compounds. LIII : Synthesis and structural characterization of binuclear µ,µ'-dichloro-, dibromo- and diiodo-bis[(pyridine)(triphenylphosphine)copper(I)] complexes, and their pyridine-4-carbonitrile analogues

Mixed base pyridine (py)/triphenylphosphine adducts of the copper(1) halides, CuX, have been synthesized for 1 : 1 : 1 stoichiometry for X = chloride and iodide; single-crystal X-ray structure determinations of these show them to be isomorphous and isostructural with that of the bromide recorded elsewhere, being µ,µ′- dihalo-bridged dimers , [(PPh3)( py )CuX2Cu( py )(PPh3)], monoclinic, C2/c, a ≈ 26.2, b ≈ 14.3, c ≈ 11 .2 A , β ≈ 95, Z = 4 dimers. The bromide has been isolated as a new monoclinic C 2/m polymorph, a 11 .279(8), b 14.268(6), c 13.858(4) A, β 109.33(6)o, Z=4 dimers, and details of its structure are also recorded. The structures of their pyridine-4-carbonitrile (pycn) analogues have also been determined and found to be also binuclear, with no cyano-copper interactions; these also are an isomorphous, isostructural series, monoclinic P21/n, a ≈ 15.4, b ≈ 8.1, c ≈ 17.9 A , β ≈ 101 o, Z = 2 dimers. In each series of dimers, one half of the dimer is crystallographically independent, the generators of the other half being twofold rotor (C2/c phase), mirror (C2/m phase) and inversion centre (P21/n phase) respectively.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLIV. Synthesis and Conformational Systematics of 1 : 1 Copper(I) Halide Nitrogen Base Adducts as [(N-base)CuX2Cu(N-base)] Dimers (X = Cl, Br, I) and [(N-Base)CuX] Monomers (X = Cl, Br)

A complete array of [LcuX2CuL] dimers for the system CuX/monodentate nitrogen base, L, all X = Cl, Br, I, has been synthesized and structurally characterized for the highly hindered pyridine base L ≈ 1,2,3,4,5,6,7,8-octahydroacridine, enabling comparison of stereochemical parameters with previously characterized [L2CuX2CuL2] arrays (L monodentate ). With L-2,2,6,6-tetramethylpiperidine, a similar dimer is also obtained with copper(I) iodide, but with the chloride and bromide adducts linear monomers [ LCuX ] have been obtained, the first to be structurally characterized for the copper(I) halide/nitrogen base system. In the latter Cu-Cl, Br are 2.087(2) and 2.216(2), 2.202(2) A, Cu-N being 1.923(3) and 1.931(9), 1.9337) A .

Lewis-Base adducts of group 11 Metal(I) Compounds. LIV : Synthesis and structural characterization of binuclear µ,µ'-dichloro-, dibromo- and diiodo-bis[(pyridine)(triphenylphosphine)silver(I)] pyridine solvate complexes

Mixed base pyridine (py)/triphenylphosphine adducts of the silver(I) halides, AgX (X = Cl, Br, I), have been synthesized for 1 : 1 : 1 stoichiometry. The three complexes are isomorphous and isostructural, being monoclinic, P21/c, a ≈ 11.2, b ≈ 16.8, c ≈ 16.5 A , β ≈ 122 o ; the complexes are centrosymmetric µ, µ?- dihalo -bridged dimers , [(PPh3)( py )AgX2Ag( py )(PPh3)1 (Z = 2 dimers ). Although the stoichiometry of the complex itself is as above, an additional unit of pyridine per silver atom is found as solvent in the lattice, implying the unlikelihood of the existence of an independent 1 : 2 : 1 AgX : py : PPh3 molecular series. In addition, the iodide has been isolated as a different C2/m (?) disordered polymorph.

Lewis-Base Adducts of Group-11 Metal(I) Compounds. XXXI. Reaction of 2,6-Bis[1-phenyl-1-(pyridin-2-Yl)ethyl]pyridine (L), and Copper(I) Halides in Acetonitrile: Structural Characterization of Salts of the [(MeCN)Cu(meso-L)]+ Cation

Reaction of 2,6-bis[l-phenyl-1-(pyridin-2-yl)ethyl]pyridine, L, with copper(1) chloride, bromide, and iodide in acetonitrile solution has been shown to yield salts, structurally characterized by single-crystal X-ray diffraction methods as [( MeCN ) CuL ]+ [ ClCuCl ]-, (1), [( MeCN ) CuL ]+2 [XCuX2CuX]2-, X = Br (2), I (3) (both isomorphous ), all as yellow needles, and a form of (3), orange blocks, as the hemiacetonitrile solvate, (4), [( MeCN ) CuL ]+2 [IcuI2Cul]2-. MeCN . The same cation is common to all four species, containing four-coordinate copper(r), with L as meso -tridentate ligand; in (4), the most precisely defined example, Cu-N( MeCN ) is 1.919(5) A, the shortest copper(1) acetonitrile distance known, while Cu-N(L) are 2.065(5)-2.073(5) A. The reason for non-formation of species of the type [ LCuX ] appears to lie in the tridentate ligand conformation which permits coordination of acetonitrile but not larger halide species.

Lewis-base adducts of Group 11 metal(I) compounds. Part 58. Syntheses, X-ray structures, and far-infrared spectra of the novel [CuX2(bidentate ligand)]–(X = Cl or Br) anion salts of the [Cu(dpa)2]+ cation and the dimeric iodide [(dpa)Cul2Cu(dpa)][dpa = di(2-pyridyl)amine]

Reaction of copper(I) halides (CuX, X = Cl, Br, or I) in acetonitrile solution with di(2 pyridyl)amine(dpa) yields 1 : 1.5 adducts with the chloride and bromide, a 1 : 1 adduct with the iodide, and a 1 : 2 adduct with the chloride. The compounds have been characterized by spectroscopic and single-crystal X-ray methods. The 1 : 1 iodide is a dimer, [(dpa)Cul2Cu(dpa)], of a type familiar with other bidentate nitrogen base ligands, but the l : 1.5 complexes are ionic, formulated as [Cu(dpa)2]+[Cu(dpa)X2]–, containing the first structurally characterized [Cu(dpa)2]+ cations and [CuX2(bidentate ligand)]– anions, while the 1 : 2 chloride is [Cu(dpa)2]+Cl–. In the [Cu(dpa)2]+ cation mean Cu–N is ca. 2.00 A, while in the [Cu(dpa)X2]– anions Cu–N is ca. 2.05 A and Cu–Cl and Cu–Br 2.369(2), 2.302(2) and 2.490(6), 2.439(6)A respectively. The dpa ligand in all cases is essentially planar. The far i.r. spectra of the anions show bands at 214 cm–1(chloride) and 160 cm–1(bromide) which can be assigned to the asymmetric stretching mode of the CuX2 unit.

Lewis base adducts of Group 11 metal(I) compounds. Part 36. The synthesis and X-ray crystallographic characterisation of polymeric copper(I) iodide–benzonitrile (2/1)

Recrystallisation of copper(I) iodide from benzonitrile yields not the 1 : 1 adduct as with the chloride and bromide, but a novel 2 : 1 adduct, [(CuI)2(PhCN)], the nature of which has been established by single-crystal X-ray structure determination. Crystals are monoclinic, space group C2/c, a= 21.99(1), b= 15.109(6), c= 15.286(9)A, β= 125.63(4)°, Z= 16, and R= 0.033 for 2 403 ‘observed’ reflections. The compound is a novel infinite polymer based on chiral, interlocking arrays of extended ‘step’ motifs.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. XXXV : Complexes of the asymmetric bidentate ligands (L) 2-aminomethylpyridine and 2-hydrazinopyridine with copper(I) halides: Synthesis and structural characterization of [CuL2]+X-, X = Cl, Br, I

The 1:2 adducts of the copper(I) halides (CuX ; X = Cl, Br, I) with the aliphatic/aromatic bidentate nitrogen bases 2-aminomethylpyridine, H2NCH2.C5H4N, and 2-hydrazinopyridine, H2N.NH.C5H4N, L, have been synthesized by recrystallization of stoichiometric copper(I) halide/base solutions from acetonitrile . In all cases, ionic complexes [CuL2]+ X- are obtained, copper being four-coordinated by a pair of bidentate ligands, and with widely varying distortions from ideal 2 symmetry. Cu-N (aromatic) in the 2-aminomethylpyridine adducts range from 1.979(8) to 2.037(5)Ǻ; while Cu-N(H2) are 2.102(9)-2.172(10)Ǻ, N( Ar )-Cu-N( Ar ) angles [130.7(2)-143.2(4)°] are larger than N(H2)-Cu-N(H2)[114.8(2)-116.3(4)°]. Comparable values for the 2-hydrazinopyridine complexes are 1.95(1)-2.036(5), 2.085(4)-2.214(7)Ǻ; 124.1(2)-140.8(4), 94.5(3)-128.0(3)°. In no case does the halide anion coordinate to the copper, displacing the aliphatic nitrogen donor group; rather it is stabilized in the crystal lattice by strong NH2…X hydrogen bonding.