Engineering silver(I) coordination networks through hydrogen bonding

The silver(I) coordination networks [Ag2(mu-O2CCF3)2(mu-NN)2](infinity) exist as a polymer of macrocycles or a double-stranded polymer when NN = 1,2-C6H4[NHC(O)-4-C5H4N]2 or 1,2-C6H4[NHC(O)-3-C5H4N]2, respectively. Crystal engineering of the polymers is achieved through interchain hydrogen bonds.     

3D-supramolecular copper(I) cyanide coordination polymers through hydrogen bonding

The reactions of K₃[Cu(CN)₄], 3-acetylpyridine (3-Acpy) or 4-acetylpyridine (4-Acpy) in the presence of Me₃SnCl in H₂O/acetonitrile media at room temperature afford the 3D-supramolecular coordination polymers (SCPs)_∞³[Cu₂CN(μ-CN)·(3-Acpy)₂] 1 and _∞³[Cu₂CN(μ-CN)·(4-Acpy)₂] 2. The structures of 1 and 2 consist of Cu₂CN building blocks which are connected by CN groups, forming 1D-zig-zag chains. Each chain is bonded to another chain by hydrogen bonding into a 2D-layer, which is further stacked in an interwoven mode by π–π stacking interactions and hydrogen bonds in 1 and 2, as well as Cu···Cu interactions in 1, to create supramolecular 3D-network structures. The high dimensional topologies of 1 and 2 result mainly from extensive hydrogen bonding and π–π stacking. The long wavelength absorption band at 400–420 nm in the electronic spectra of 1 and 2 is assigned to a CT from copper(I) to the Acpy ligand. Compound 2 exhibits strong luminescence at 485 and 527 nm, corresponding to MLCT and metal-centered transitions, respectively.     

Singlet quenching of tetraphenylporphyrin and its metal derivatives by iron(III) coordination compounds

The quenching of fluorescence of the free-base tetraphenylporphyrin, H₂TPP, and its metal derivatives, MgTPP and ZnTPP by diverse iron(III) complexes, [Fe(CN)₆]³⁻, Fe(acac)₃, [Fe(mnt)₂]⁻, Fe(Salen)Cl, [Fe₄S₄(SPh)₄]²⁻·, FeTPPCl and [Fe(Cp)₂]⁺ has been studied both in homogeneous medium (CH₃CN) and micellar media, SDS., CTAB and Triton X-100. The quenching efficiencies are analysed in terms of diffusional encounters and it has been possible to separate static quenching components. The quenching constants are dependent on the nature of the ligating atoms around iron(III) and also on the extent of π-conjugation of the ligands. The quenching mechanism has been investigated using steady-state irradiation experiments. Evidence for oxidative quenching by iron(III) complexes was obtained, though the spin multiplicities of the excited electronic states of iron(III) complexes permit both energy and electron transfer mechanisms for quenching of the singlet excited state of the porphyrins.     

Lanthanide luminescent anion sensing: evidence of multiple anion recognition through hydrogen bonding and metal ion coordination

The delayed lanthanide luminescence of the terbium [Tb(III)] diaryl-urea complex 1xTb is significantly enhanced upon sensing of dihydrogenphosphate (H2PO4(-)) in CH3CN, which occurs through multiple anion binding through hydrogen bonding interactions and potential metal ion coordination to Tb(III).     

High-affinity pyrophosphate receptor by a synergistic effect between metal coordination and hydrogen bonding in water

We have developed the tightest binding PPi receptor reported to date by a combination of metal coordination and hydrogen bonding interaction in water.     

Arylgold(I) and aryl(triphenylphosphine)gold(I)compounds

Novel monomeric benzyl- and aryl-gold(I) triphenylphosphine complexes have been prepared. Pure, uncomplexed 2-[(dimethylamino)methyl]-phenylgold(I) has been isolated from the reaction of tetranuclear bis {2-[(dimethylamino)methyl]phenyl}goldlithium (R₄ Au₂ Li₂) with trimethyltin bromide.     

Switching from bonding to nonbonding: temperature-dependent metal coordination in a zinc(II) sulfadiazine complex

The metal coordination in the mononuclear complex diamminebis(sulfadiazine)zinc shows a unique temperature dependence: High-resolution diffraction data prove that the coordination is almost tetrahedral at 100 K, whereas a fifth longer interaction becomes relevant at 200 K. The change in the geometry is fully reversible and is also reflected in the charge density of the compound.     

A luminescent gold(I)-copper(I) cluster with unprecedented carbon-centered trigonal prismatic hexagold

An unprecedented trigonal prismatic (μ(6)-C)Au(6) structure has been found in a novel gold(I)-copper(I) cluster with a hypercoordinated carbon, [CAu(6)Cu(2)(dppy)(6)](BF(4))(4); the incorporation of copper ions enhances the rigidity and integrity of the cluster and turns on the bright red solution luminescence.     

CoAu2(CN)4(NITpPy)2(H2O)2]n: a new 2-D interdigitating complex containing dicyanoaurate(I) anion, a radical, and cobalt(II) ion incorporating gold...gold and hydrogen bonding interactions

A novel complex, [[CoAu2(CN)4(NITpPy)2(H2O)2]]n, 1, containing the cobalt(II) ion, dicyanoaurate(I) anion, and nitronyl nitroxide radical building blocks, has been prepared and structurally characterized by single-crystal X-ray analysis. The structure of complex 1 illustrates that aurophilicity and hydrogen bonding interactions increase dimensionality, generating a 2-D interdigitating system. The spectroscopic and magnetic properties have been investigated.     

Hybrid coordination polymer constructed from beta-octamolybdates linked by quinoxaline and its oxidized product benzimidazole coordinated to binuclear copper(I) fragments

The one-dimensional polymer, [Cu(2)(C(8)H(6)N(2))(2)(C(7)H(6)N(2))](2)[Mo(8)O(26)] (1), which consists of beta-[Mo(8)O(26)](4)(-) anions linked by quinoxaline and its oxidized product benzimidazole ligands coordinated to binuclear copper(I) fragments, provides the first demonstration that the isolated copper(I) complex under hydrothermal conditions "captures" the reduction product of original starting organonitrogen ligand to form a copper(I)-beta-octamolybdate complex.     

The coordination and polymerisation of cyclic 1,3-dienes by gold(I) cations

Cyclopentadiene and 1,3-cyclohexadiene are readily polymerised by [LAu][X]. With specific ancillary ligands polymerisation was suppressed and a molecular species involving an Au(I) cation η(2)-bonding CpH was isolated and whose structure was probed in both the solid state and in solution.     

Macrometallocycle binuclear NHC silver(I) complex with bridging azobenzene: Synthesis,structure and recognition for hydrogen sulfate

One bis-imidazolium salt 2,2′-di[2’’-(N-methyl-imidazoliumyl)ethoxyl]azobenzene hexafluorophosphate (LH₂·(PF₆)₂) and its macrometallocycle binuclear N-heterocyclic carbene silver(I) complex [(LAg)₂](PF₆)₂ were prepared and characterized. The structure of [(LAg)₂](PF₆)₂ was determined by X-ray single crystal diffraction, ¹H NMR and ¹³C NMR spectroscopy. In complex [(LAg)₂](PF₆)₂, one 34-membered macrometallocycle was formed by two biscarbene ligand L and two silver(I) ions. Additionally, the selective recognition of hydrogen sulfate using [(LAg)₂](PF₆)₂ as a chemosensor was investigated on the basis of fluorescence titrations, ultraviolet titrations, ¹H NMR titrations, HRMS and IR spectra. Complex [(LAg)₂](PF₆)₂ was demonstrated to be an effective chemosensor for hydrogen sulfate.     

An antiferromagnetically coupled dimeric Ni(II) complex anion and its counter cationic monomeric Ni(II) complex, and some other mononuclear transition metal compounds using some neutral ligands

Synthesis and single crystal X-ray diffraction studies of four transition metal complexes [Mn(L₁)](ClO₄)₂ (1), [Cu(L₁)](ClO₄)₂ (2), [Ni₂(L₂)(NCS)₆][Ni(L₁)] (3) and [Mn(bzpy)(NCS)₂] (4) with neutral ligands [L₁ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-yl phenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine, L₂ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}piperazine-1yl)ethyl]amine, bzpy = 2-benzoylpyridine] are reported. The trinuclear nickel(II) complex 3 is made of a dinuclear anion and a mononuclear cation. Variable-temperature magnetic susceptibility and variable-field magnetisation studies performed on 3 suggest weak antiferromagnetic coupling (J = −0.7 cm⁻¹) between the two metals of the dinuclear entity, but no magnetic interaction between the anionic and cationic counterparts.     

A tris(2-quinolylmethyl)amine scaffold that promotes hydrogen bonding within the secondary coordination sphere

A new quinolyl-based ligand presents three amide functionalities to act as hydrogen-bond accepting groups to a metal-bound substrate at a well-defined distance. As a confirmation of the design strategy, CH(3)CN coordinated to copper(II) participates in CH-O interactions in the solid state and in solution.     

Connecting binuclear Pd(III) and mononuclear Pd(IV) chemistry by Pd-Pd bond cleavage

Oxidation of binuclear Pd(II) complexes with PhICl(2) or PhI(OAc)(2) has previously been shown to afford binuclear Pd(III) complexes featuring a Pd-Pd bond. In contrast, oxidation of binuclear Pd(II) complexes with electrophilic trifluoromethylating ("CF(3)(+)") reagents has been reported to afford mononuclear Pd(IV) complexes. Herein, we report experimental and computational studies of the oxidation of a binuclear Pd(II) complex with "CF(3)(+)" reagents. These studies suggest that a mononuclear Pd(IV) complex is generated by an oxidation-fragmentation sequence proceeding via fragmentation of an initially formed, formally binuclear Pd(III), intermediate. The observation that binuclear Pd(III) and mononuclear Pd(IV) complexes are accessible in the same reactions offers an opportunity for understanding the role of nuclearity in both oxidation and subsequent C-X bond-forming reactions.