Copper(I) thiocyanate networks with aromatic diimine ligands

A total of five new CuSCN-LL complexes with aromatic diimine ligands, LL = quinoxaline (Qox), quinazoline (Qnz), phthalazine (Ptz), 2-aminopyrazine (2-NH2Pyz), and 2-methoxypyrazine (2-MeOPyz) have been prepared and characterized by crystallographic methods. The following compounds are reported: (CuSCN)2(Qox) (1), (CuSCN)(Qnz) (2), (CuSCN)2(Ptz) (3), (CuSCN)2(2-NH2Pyz) (4), and (CuSCN)(2-MeOPyz) (5). Compounds 1–4 were prepared using an extended aqueous reflux method in the presence of KSCN and ammonia. Compound 5 was prepared by directly reacting solid CuSCN with the liquid ligand. In complexes 2 and 5, LL is monodentate, while in others LL is bridging bidentate. All network structures are 2-D sheets, consisting of μ2-LL-crosslinked CuSCN ladders for 1 and 4, LL-decorated CuSCN sheets for 2 and 5, and unusual μ2-LL-“stapled” sheets for 3

Poly[l-2-aminopyrazine-j2 N1 :N4 - l-cyanido-copper(I)]: A Three-dimensional Network From Laboratory Powder Diffraction Data

In the title compound, [Cu(CN)(C4H5N3)]n or [Cu(-CN)(-PyzNH2)]n (PyzNH2 is 2-amino­pyrazine), the CuI center is tetra­hedrally coordinated by two cyanide and two PyzNH2 ligands. The CuI-cyano links give rise to [Cu-CN] chains running along the c axis, which are bridged by bidentate PyzNH2 ligands. The three-dimensional framework can be described as being formed by two inter­penetrated three-dimensional honeycomb-like networks, both made of 26-membered rings of composition [Cu6(-CN)2(-PyzNH2)4]

Threaded Structure and Blue Luminescence of (CuCN)20(Piperazine)7

The structurally unique and highly luminescent 20 : 7 complex of CuCN with piperazine (Pip) was formed under aqueous conditions; its structure reveals two interpenetrated 2D sub-networks in 6 : 1 ratio: (CuCN)2(Pip) and (CuCN)8(Pip), the latter consisting of Cu18(CN)16(Pip)2 macrocycles

Nickel(II) and Cobalt(II) Nitrate and Chloride Networks with 2-aminopyrimidine

The coordination chemistry of 2-aminopyrimidine (PymNH2) with nickel(II) and cobalt(II) nitrate and chloride is reported, including seven new X-ray crystal structures. Two [Ni(NO3)2(PymNH2)2(OH2)] isomers were found (A: C2/c, a=13.3006(5), b=7.9727(3), c=28.5453(11), β=101.758(2), V=2963.48(19), Z=8 and B·1/2 acetone: P21/c, a=7.66060(10), b=10.6792(2), c=20.6790(3), β=100.2970(10), 1664.48(5), Z=4). In both cases one nitrate is monodentate and the other is chelating and the PymNH2 ligands coordinate through ring nitrogen atoms. Hydrogen bonding results in double sheet structure for isomer A, and a three dimensional channeled network for isomer B. [Co(NO3)2(PymNH2)2(OH2)] (C2/c, a=13.3507(2), b=7.99520(10), c=28.6734(3), β=102.3540(10), V=2989.77(7), Z=8) is isostructural to Ni isomer A. [CoCl2(PymNH2)] (Cmcm, a=3.6139(2), b=14.3170(7), c=12.9986(7), V=672.55(6), Z=4) is a sheet coordination network, consisting of corner-sharing chains of Co2(μ-Cl)2 bridged by PymNH2 through ring nitrogen atoms; [CoCl2(PymNH2)2] (C2/c, a=11.2774(6), b=6.5947(4), c=16.5687(9), β=92.269(3), V=1231.27(12), Z=4) is a tetrahedral molecule knit into a ribbon structures through pairs of hydrogen bonds. Isostructural trans-[NiCl2(PymNH2)4] (C2/c, a=7.67760(10), b=18.7224(3), c=15.0418(2), β=99.6740(10), V=2131.41(5), Z=4) and trans-[CoCl2(PymNH2)4] (C2/c, a=7.69120(10), b=18.5957(2), c=15.1091(2), β=99.5280(10), V=2131.14(5), Z=4) are simple octahedral molecules, with hydrogen-bonding producing sheet structures

Bis([mu]-thio­phene-2-carbaldehyde thio­semicarbazonato)bis­[acetonitrile­copper(I)] bis­(tetra­fluoro­borate)

The title compound, [Cu2(C6H7N3S2)2(C2H3N)2](BF4)2, is a dimer with a central Cu2S2 core resulting from thio­semi­carbazone sulfur bridging. Both Cu-TCT units (TCT is the thio­phene-2-carboxaldehyde thio­semicarbazone anion) are roughly planar and are parallel to one another and perpendicular to the Cu2S2 plane

Synthesis, Protonation, and Reduction of Ruthenium–Peroxo Complexes with Pendent Nitrogen Bases

Cyclopentadienyl and pentamethylcyclopentadienyl ruthenium­(II) complexes have been synthesized with cyclic (RPCH₂NR′CH₂)₂ ligands, with the goal of using these [Cp^R′′Ru­(P^R₂N^R′₂)]⁺ complexes for catalytic O₂ reduction to H₂O (R = <i>t</i>-butyl, phenyl; R′ = benzyl, phenyl; R″ = methyl, H). In each compound, the Ru is coordinated to the two phosphines, positioning the amines of the ligand in the second coordination sphere where they may act as proton relays to a bound dioxygen ligand. The phosphine, amine, and cyclopentadienyl substituents have been systematically varied in order to understand the effects of each of these parameters on the properties of the complexes. These Cp^R″Ru­(P^R₂N^R′₂)⁺ complexes react with O₂ to form η²-peroxo complexes, which have been characterized by NMR, IR, and X-ray crystallography. The peak reduction potentials of the O₂ ligated complexes have been shown by cyclic voltammetry to vary as much as 0.1 V upon varying the phosphine and amine. In the presence of acid, protonation of these complexes occurs at the pendent amine, forming a hydrogen bond between the protonated amine and the bound O₂. The ruthenium–peroxo complexes decompose upon reduction, precluding catalytic O₂ reduction. The irreversible reduction potentials of the protonated O₂ complexes depend on the basicity of the pendent amine, giving insight into the role of the proton relay in facilitating reduction

Effect of Basic Site Substituents on Concerted Proton–Electron Transfer in Hydrogen-Bonded Pyridyl–Phenols

Separated concerted proton–electron transfer (sCPET) reactions of two series of phenols with pendent substituted pyridyl moieties are described. The pyridine is either attached directly to the phenol (<b>HOAr-pyX</b>) or connected through a methylene linker (<b>HOArCH</b>_<b>2</b><b>pyX</b>) (X = 4-NO₂, 5-CF₃, 4-CH₃, and 4-NMe₂). Electron-donating and -withdrawing substituents have a substantial effect on the chemical environment of the transferring proton, as indicated by IR and ¹H NMR spectra, X-ray structures, and computational studies. One-electron oxidation of the phenols occurs concomitantly with proton transfer from the phenolic oxygen to the pyridyl nitrogen. The oxidation potentials vary linearly with the p<i>K</i>_a of the free pyridine (pyX), with slopes slightly below the Nerstian value of 59 mV/p<i>K</i>_a. For the <b>HOArCH</b>_<b>2</b><b>pyX</b> series, the rate constants <i>k</i>_sCPET for oxidation by NAr₃^•+ or [Fe­(diimine)₃]³⁺ vary primarily with the thermodynamic driving force (Δ<i>G</i>°_sCPET), whether Δ<i>G</i>° is changed by varying the potential of the oxidant or the substituent on the pyridine, indicating a constant intrinsic barrier λ. In contrast, the substituents in the <b>HOAr-pyX</b> series affect λ as well as Δ<i>G</i>°_sCPET, and compounds with electron-withdrawing substituents have significantly lower reactivity. The relationship between the structural and spectroscopic properties of the phenols and their CPET reactivity is discussed

Effect of Basic Site Substituents on Concerted Proton–Electron Transfer in Hydrogen-Bonded Pyridyl–Phenols

Separated concerted proton–electron transfer (sCPET) reactions of two series of phenols with pendent substituted pyridyl moieties are described. The pyridine is either attached directly to the phenol (<b>HOAr-pyX</b>) or connected through a methylene linker (<b>HOArCH</b>_<b>2</b><b>pyX</b>) (X = 4-NO₂, 5-CF₃, 4-CH₃, and 4-NMe₂). Electron-donating and -withdrawing substituents have a substantial effect on the chemical environment of the transferring proton, as indicated by IR and ¹H NMR spectra, X-ray structures, and computational studies. One-electron oxidation of the phenols occurs concomitantly with proton transfer from the phenolic oxygen to the pyridyl nitrogen. The oxidation potentials vary linearly with the p<i>K</i>_a of the free pyridine (pyX), with slopes slightly below the Nerstian value of 59 mV/p<i>K</i>_a. For the <b>HOArCH</b>_<b>2</b><b>pyX</b> series, the rate constants <i>k</i>_sCPET for oxidation by NAr₃^•+ or [Fe­(diimine)₃]³⁺ vary primarily with the thermodynamic driving force (Δ<i>G</i>°_sCPET), whether Δ<i>G</i>° is changed by varying the potential of the oxidant or the substituent on the pyridine, indicating a constant intrinsic barrier λ. In contrast, the substituents in the <b>HOAr-pyX</b> series affect λ as well as Δ<i>G</i>°_sCPET, and compounds with electron-withdrawing substituents have significantly lower reactivity. The relationship between the structural and spectroscopic properties of the phenols and their CPET reactivity is discussed