Dramatic Improvement of Homogeneous Carbon Dioxide and Bicarbonate Electroreduction Using a Tetracationic Water-Soluble Cobalt Phthalocyanine.

Electrochemical conversion of carbon dioxide (CO) offers the opportunity to transform a greenhouse gas into valuable starting materials, chemicals, or fuels. Since many CO capture strategies employ aqueous alkaline solutions, there is interest in catalyst systems that can act directly on such capture solutions. Herein, we demonstrate new catalyst designs where the electroactive molecules readily mediate the CO-to-CO conversion in aqueous solutions between pH 4.

Inducing Platinophilic Interactions in [Pt(SCN)] Salts by Cation Tuning.

A series of simple [Pt(SCN)] salts with a variety of cations was synthesized and characterized using X-ray crystallography to determine factors that could induce platinophilic interactions between [Pt(SCN)] anions, including cation size and shape, charge, and ability to participate in hydrogen bonding. The salts [N(PPh)][Pt(SCN)], [AsPh][Pt(SCN)], and [Co(1,10-phenanthroline)][Pt(SCN)] feature bulky, noncoordinating cations where the [Pt(SCN)] anions are completely separated from each other, with no Pt-Pt interactions present. Salts containing the hydrogen-bonding cations [Co(NH)][Pt(SCN)] and [Co(en)][Pt(SCN)] (en = 1,2-ethylenediamine) display close Pt-Pt distances, with both compounds exhibiting platinophilic interactions with distances of 3.

Unusually short unsupported Au(III)⋯Au(III) aurophilic contacts in emissive lanthanide tetracyanoaurate(III) complexes.

A series of [Au(CN)] salts with lanthanide 2,2'-bipyridine dioxide cations features Au(III) aurophilic interactions between [Au(CN)] groups, with Au⋯Au distances of 3.3603(4) Å and 3.4354(4) Å that are shorter than any previously reported.

Inducing ring distortions in unsubstituted metallophthalocyanines using axial N-heterocyclic carbenes.

A series of metallophthalocyanine (PcM) complexes with axial N-heterocyclic carbene ligands (NHC; 1,3-diisopropylimidazol-2-ylidene (DIP) and 1,3-dimethylbenzimidazol-2-ylidene (DMB)) were prepared and structurally characterized. PcCo(DIP), PcZn(DIP), and PcZn(DMB) are five-coordinate complexes with mild dome-type Pc-ring distortions, while PcFe(DIP) is six-coordinate and has a very large ruffle-type ring-distortion with respect to typical PcM(L) systems. The distortion is induced by the highly steric axial DIP ligands.

Cadmium Dicyanoaurates and Their Reaction with Ammonia.

The synthesis and crystal structures of two anionic cadmium dicyanoaurate coordination polymers, [BuN][(CdCl)(Au(CN))][CdCl] (TCCA) and [BuN][Cd(Au(CN))], and their reaction with ammonia vapour is reported. TCCA and the isostructural [BuN][(CdBr)(Au(CN))][CdBr] form 3-D arrays with [CdX] (X=Cl, Br) cubane clusters linked from each octahedral Cd(II) centre by three bridging [Au(CN)] units. TCCA reacts with ammonia with concentrations of 1000 ppm or higher to give a product with a quantum yield of 0.

Anisotropic Thermal Expansion of Structurally Related Lanthanide-Mercury(II) Cyanide Coordination Polymers.

Three sets of related lanthanide-mercury(II) cyanide coordination polymers were synthesized by the reaction of LnCl·HO (Ln = Ce, Nd, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) with Hg(CN) and structurally characterized. [Ce(OH)][Hg(CN)Cl]·2HO is a 3-D material with sheet-based architecture; its thermal expansion behavior shows uniaxial negative thermal expansion (-18.3(8), 39(2), and 68.

Tuning the visible colour of octahedral manganese(III) phthalocyanines axial ligand exchange.

A series of [PcMnL]SbF complexes (Pc = phthalocyanine) was synthesized and structurally characterized by stripping the chloride from PcMnCl with AgSbF in -dichlorobenzene and adding a range of donor ligands (L = THF, pyridine, -dimethylaminopyridine (DMAP), PhPO, -methylimidazole (MeIm), MeCN) to the resulting solution. Addition of or exposure to water where L = heterocyclic amines yielded μ-oxo complexes of the form [PcMnL]O, which were structurally characterized for L = DMAP and MeIm. The [PcMnL]SbF complexes have an increased solubility in organic solvents, where the axial ligands inhibit the characteristic ring π-π aggregation of PcM complexes.

Contemporary Strategies for Immobilizing Metallophthalocyanines for Electrochemical Transformations of Carbon Dioxide.

Metallophthalocyanine (PcM) coordination complexes are well-known mediators of the electrochemical reduction of carbon dioxide (CO). They have many properties that show promise for practical applications in the energy sector. Such properties include synthetic flexibility, a high stability, and good efficiencies for the reduction of CO to useful feedstocks, such as carbon monoxide (CO).

Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe], [PcFeL], and [PcFeX] Complexes: Story of a Double Flip.

The reduction of iron(II) phthalocyanine (Pc(2-)Fe) or its bisaxially coordinated complexes results in the formation of the purple/red [PcFe], [PcFeL], and [PcFeX] (L is neutral and X is anionic ligand) species. The X-ray structure of the [K(DME)][PcFe] complex exhibits a square-planar [PcFe] anion. H NMR spectra of the reduced species have one or two phthalocyanine broad peaks between 15 and 17 ppm.

Highly emissive polymorphs of anhydrous cadmium tetracyanoplatinate and their solvated coordination networks.

Two anhydrous polymorphs of cadmium cyanoplatinate Cd[Pt(CN)] coordination polymers have been synthesized and thermally, spectroscopically, and structurally characterized. α-Cd[Pt(CN)] and β-Cd[Pt(CN)] are densely packed, highly emissive 3-D solids, with quantum yields of 0.85 ( = 520 nm) and 0.

Exciton Coupling in Redox-Active Salen based Self-Assembled Metallacycles.

The incorporation of a redox-active nickel salen complex into supramolecular structures was explored via coordination-driven self-assembly with homobimetallic ruthenium complexes (bridged by oxalato or 5,8-dihydroxy-1,4-naphthoquinato ligands). The self-assembly resulted in the formation of a discrete rectangle using the oxalato complex and either a rectangle or a catenane employing the larger naphthoquinonato complex. The formation of the interlocked self-assembly was determined to be solvent and concentration dependent.

Synthesis and Structural Characterization of a Silver(I) Pyrazolato Coordination Polymer.

Coinage metal(I)···metal(I) interactions are widely of interest in fields such as supramolecular assembly and unique luminescent properties, etc. Only two types of polynuclear silver(I) pyrazolato complexes have been reported, however, and no detailed spectroscopic characterizations have been reported. An unexpected synthetic method yielded a polynuclear silver(I) complex (L1Clpz = 4-chloride-3,5-diisopropyl-1-pyrazolate anion) by the reaction of {[Ag(μ-L1Clpz)]} with (BuN)[Ag(CN)].

Structural Diversity of F-Element Monophthalocyanine Complexes.

The preparation and structural characterization of a series of lanthanide and uranium(IV) phthalocyanine halide complexes were achieved by reaction of the corresponding metal halide with Li Pc. A preliminary survey of their reactivity includes ring reduction of Li(THF) [PcUCl ] with KC leading to the first structurally characterized Pc actinide complex, hydrolysis of PcDyCl(DMSO) to PcDyOH(H O) and preparation of a unique trimeric triangular Li(PcDy) (OH) (H O) cluster.

Synthesis of Sterically Congested 2,2'-Bi(Adamantyl)-Based Alcohol and Amines.

Sterically congested chiral alcohol and amines have gained tremendous attention in the design of asymmetric catalysts. Herein, the synthesis of a sterically congested bis-adamantane framework-based chiral alcohol, (1,2,3,4)-4-(2-adamantyl)adamantan-2-ol, and amine, (1,2,3,4)-4-(2-adamantyl)adamantan-2-amine, is described. Access to these sterically encumbered compounds is found via the preparation of an enantioenriched 4-adamantyladamantan-2-one intermediate, which was synthesized in 6 steps from adamantan-2-one.

Zinc Tetracyanoplatinate: A Reversible Luminescence-Based Ammonia Sensor.

ZnPt(CN) was shown to be an effective material for ammonia sensing, and can be synthesized using either solution or mechanochemical methods. A combination of luminescence and Raman spectroscopy revealed that multiple species are involved in the reaction between ammonia and ZnPt(CN) . The crystal structure of one of these species, Zn(NH ) Zn(NH ) (Pt(CN) ) , was elucidated.

Coordination-driven assembly of a supramolecular square and oxidation to a tetra-ligand radical species.

The design and synthesis of a supramolecular square was achieved by coordination-driven assembly of redox-active nickel(ii) salen linkers and (ethylenediamine)palladium(ii) nodes. The tetrameric geometry of the supramolecular structure was confirmed via MS, NMR, and electrochemical experiments. While oxidation of the monomeric metalloligand Schiff-base affords a Ni(iii) species, oxidation of the coordination-driven assembly results in ligand radical formation.

Facile tuning of strong near-IR absorption wavelengths in manganese(iii) phthalocyanines via axial ligand exchange.

The facile tuning of near-infrared absorption of manganese(iii) phthalocyanines was accomplished by changing the nature and number of bound axial ligands. For a series of axial ligands on manganese α-octabutoxyphthalocyanine and α-octakis-(isopropylthio)phthalocyanine, the electron density on the metal and its displacement from the Pc-ring plane both control the position of the complex's Q-band. For these two macrocycles, this strong absorption band could be tuned over a λmax range of 815-948 nm by axial ligand exchange.

Ring-Oxidized Zinc(II) Phthalocyanine Cations: Structure, Spectroscopy, and Decomposition Behavior.

A bromonium oxidizing agent was used to produce a ring-oxidized zinc phthalocyanine (PcZn), [PcZn(solvent)][BAr] (1·solvent), in good yield. This material is dimeric in the solid state with one axially coordinated solvent [tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME)] and close intradimer ring-ring distances of 3.18 and 3.

Redox behaviour of ([fc(NPPr)]Fe), formation of an iron-iron bond and cleavage of azobenzene.

The redox behaviour of the dimeric tetrairon complex, ([fc(NPiPr2)2]Fe)2 (where fc(NPiPr2)2 = 1,1'-(C5H4NPiPr2)2Fe) has been investigated. Upon reduction with KC8 an Fe-Fe bond is formed with the complex maintaining a high spin configuration and having the formula [K(THF)6]([fc(NPiPr2)2]Fe)2. In contrast, oxidation of the complex is ligand based; for example, addition of the 1,2-diiodoethane (I2 equivalent) results in the formation of the monomeric iron(ii) diiodide [fc(NiPr2I)2]FeI2 wherein the phosphine is oxidized.

Designing anisotropic cyanometallate coordination polymers with unidirectional thermal expansion (TE): 2D zero and 1D colossal positive TE.

Oxidative addition of halogens to tetracyanoplatinate results in the formation of a Pt(iv)-building block that, combined with Cu(ii), forms coordination polymers Cu(HO)[PtX(CN)] (X = Br, Cl). These materials exhibit directional anisotropic thermal expansion: nearly zero expansion within the cyanometallate sheets and positive thermal expansion in the third dimension.

Phthalocyanine as a redox-active platform for organometallic chemistry.

A systematic approach to the synthesis of σ-organometallophthalocyanines is described. Structurally characterized σ-organoPcM complexes are presented, including the first PcCr-aryl, PcCr-alkynyl, and PcCr-Wittig complexes - representing the first examples of these classes of complexes for any metallophthalocyanine - and the first PcCr-alkyl complexes, which span three chromium and two Pc-ring oxidation states. This represents a rational marriage of the broad organometallic and phthalocyanine fields, opening the door for the exploration of this classical, stable, redox-active macrocycle as an ancillary ligand in metal-carbon chemistry.

Copper(II) Dihalotetracyanoplatinate(IV) Coordination Polymers and Their Vapochromic Behavior.

The coordination polymers [Cu(HO)(μ-NC)PtX] (X = Cl, Br) form networks of square grid sheets that align in a staggered manner with one another via weak X···X interactions. Upon stepwise dehydration, the layers fuse, forming a 3-D network of distorted cubes. The materials were tested for visible vapochromic, Raman, and IR response to dimethyl sulfoxide, N,N-dimethylformamide, and pyridine.

Color-Tunable and White-Light Luminescence in Lanthanide-Dicyanoaurate Coordination Polymers.

The new lanthanide-dicyanoaurate coordination polymers [BuN][Ln(NO)Au(CN)] (Ln = Sm, Dy) and Sm[Au(CN)]·3HO were prepared and structurally characterized and their luminescence spectra described. The emissions of solid-solutions of [BuN][Ln(NO)Au(CN)] (Ln = Ce, Sm, Eu, Tb, and Dy) were explored with an emphasis on their capacity for luminescent color tuning and white-light emission via the selection of composition, excitation wavelength, and temperature. Specifically, the binary solid-solutions [BuN][CeDy(NO)Au(CN)] and [BuN][SmTb(NO)Au(CN)], and the ternary solid-solutions [BuN][CeSmTb(NO)Au(CN)] and [BuN][CeEuTb(NO)Au(CN)], were prepared and examined in terms of suitability for color-tuning capacity.

Mixed Cu(i)/Au(i) coordination polymers as reversible turn-on vapoluminescent sensors for volatile thioethers.

Vapour-phase thioethers play an important role in a wide number of fields, including plant biology, chemical weapon disposal, and brewing but few sensor materials are known. The emissive coordination polymer CuAuCN does not react with vapour phase dimethyl sulphide (DMS) or diethyl sulphide (DES) despite the independent synthesis of emissive [CuAuCN](DMS) and [CuAuCN](DES) from their constituent components in solution. However, the doped CuAuCN rapidly reacts in the solid state with both of these vapour phase thioethers reversibly, with a change in emission from 380/560 nm to 460 nm (DMS) or 420 nm (DES), illustrating that doping the inactive parent CuAuCN with Cu(i) generates an active sensor material.

Dicyanoaurate-based heterobimetallic uranyl coordination polymers.

The first series of uranyl ([UO])-dicyanoaurate coordination polymers and molecular complexes has been synthesized. Reactions of [A][Au(CN)] (A = [BuN] or [(PhP)N] ([PPN])) and uranyl nitrate in alcoholic solvents in ambient light led to [A][(UO)(μ-η:η-O)(NO)(μ-Au(CN))], which incorporates peroxo ligands into a one-dimensional ladder topology with alternating aurophilic and peroxo rungs. Conducting the reaction with non-alcoholic solvents formed two polymorphs of a one-dimensional chain, [PPN][UO(NO)Au(CN)], from acetone, and a molecular analogue, [PPN][UO(NO)(Au(CN))], from acetonitrile, none of which exhibited aurophilic interactions.