Vapochromic Behaviour of M[Au(CN)2]2-Based Coordination Polymers (M = Co, Ni)

A series of M[Au(CN)2]2(analyte)x coordination polymers (M = Co, Ni; analyte = dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), pyridine; x = 2 or 4) was prepared and characterized. Addition of analyte vapours to solid M(μ-OH2)[Au(CN)2]2 yielded visible vapochromic responses for M = Co but not M = Ni; the IR νCN spectral region changed in every case. A single crystal structure of Zn[Au(CN)2]2(DMSO)2 revealed a corrugated 2-D layer structure with cis-DMSO units. Reacting a Ni(II) salt and K[Au(CN)2] in DMSO yielded the isostructural Ni[Au(CN)2]2(DMSO)2 product. Co[Au(CN)2]2(DMSO)2 and M[Au(CN)2]2(DMF)2 (M = Co, Ni) complexes have flat 2-D square-grid layer structures with trans-bound DMSO or DMF units; they are formed via vapour absorption by solid M(μ-OH2)[Au(CN)2]2 and from DMSO or DMF solution synthesis. Co[Au(CN)2]2(pyridine)4 is generated via vapour absorption by Co(μ-OH2)[Au(CN)2]2; the analogous Ni complex is synthesized by immersion of Ni(μ-OH2)[Au(CN)2]2 in 4% aqueous pyridine. Similar immersion of Co(μ-OH2)[Au(CN)2]2 yielded Co[Au(CN)2]2(pyridine)2, which has a flat 2-D square-grid structure with trans-pyridine units. Absorption of pyridine vapour by solid Ni(μ-OH2)[Au(CN)2]2 was incomplete, generating a mixture of pyridine-bound complexes. Analyte-free Co[Au(CN)2]2 was prepared by dehydration of Co(μ-OH2)[Au(CN)2]2 at 145 °C; it has a 3-D diamondoid-type structure and absorbs DMSO, DMF and pyridine to give the same materials as by vapour absorption from the hydrate

Synthesis and Electronic Structure Determination of Uranium(VI) Ligand Radical Complexes

   Pentagonal bipyramidal uranyl complexes of salen ligands, N,N’-bis(3-tert-butyl-(5R)-salicylidene)-1,2-phenylenediamine, in which R = tBu (1a), OMe (1b), and NMe2 (1c), were prepared and the electronic structure of the one-electron oxidized species [1a-c]+ were investigated in solution. The solid-state structures of 1a and 1b were solved by X-ray crystallography, and in the case of 1b an asymmetric UO22+ unit was found due to an intermolecular hydrogen bonding interaction. Electrochemical investigation of 1a-c by cyclic voltammetry showed that each complex exhibited at least one quasi-reversible redox process assigned to the oxidation of the phenolate moieties to phenoxyl radicals. The trend in redox potentials matches the electron-donating ability of the para-phenolate substituents. The electron paramagnetic resonance spectra of cations [1a-c]+ exhibited gav values of 1.997, 1.999, and 1.995, respectively, reflecting the ligand radical character of the oxidized forms, and in addition, spin-orbit coupling to the uranium centre. Chemical oxidation as monitored by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy afforded the one-electron oxidized species. Weak low energy intra-ligand charge transfer (CT) transitions were observed for [1a-c]+ indicating localization of the ligand radical to form a phenolate / phenoxyl radical species. Further analysis using density functional theory (DFT) calculations predicted a localized phenoxyl radical for [1a-c]+ with a small but significant contribution of the phenylenediamine unit to the spin density. Time-dependent DFT (TD-DFT) calculations provided further insight into the nature of the low energy transitions, predicting both phenolate to phenoxyl intervalence charge transfer (IVCT) and phenylenediamine to phenoxyl CT character. Overall, [1a-c]+ are determined to be relatively localized ligand radical complexes, in which localization is enhanced as the electron donating ability of the para-phenolate substituents is increased (NMe2 > OMe > tBu)

Expanding uranyl dicyanoaurate coordination polymers into the second and third dimensions

The solvothermal synthesis and characterization of a three-dimensional, interpenetrated uranyl dicyanoaurate coordination polymer, K2(UO2)2(UO2)2(Au(CN)2)2(O)2(NO3)4, from UO2(NO3)2·6H2O and KAu(CN)2 is described. The structure contains a three-dimensional (3D) lattice of planar tetranuclear uranyl–oxo–nitrate clusters connected by dicyanoaurate linkers, with the rotation of the clusters providing the increased dimensionality. The material undergoes a reversible single-crystal to single-crystal transformation on exposure to water vapour, which is taken up in the channels of the 3D system. A second uranyl dicyanoaurate coordination polymer of the form [UO2(DMSO)3(H2O)(Au(CN)2)][Au(CN)2] was structurally characterized as a linear chain of dicyanoaurate units connected by gold–gold bonds with pendant uranyl–water–DMSO adducts that are hydrogen bonded into a two-dimensional sheet. Both materials exhibit emission arising from both the uranyl moiety and the gold(I) centre and represent the first multidimensional uranyl–dicyanoaurate coordination polymers.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Thermal Expansion Behavior of M^I[AuX₂(CN)₂]‑Based Coordination Polymers (M = Ag, Cu; X = CN, Cl, Br)

Two sets of <i>trans-</i>[AuX₂(CN)₂]⁻-based coordination polymer materialsM­[AuX₂(CN)₂] (M = Ag; X = Cl, Br or M = Cu; X = Br) and M­[Au­(CN)₄] (M = Ag, Cu)were synthesized and structurally characterized and their dielectric constants and thermal expansion behavior explored. The M­[AuX₂(CN)₂] series crystallized in a tightly packed, mineral-like structure featuring 1-D <i>trans-</i>[AuX₂(CN)₂]⁻-bridged chains interconnected via a series of intermolecular Au···X and M···X (M = Ag, Cu) interactions. The M­[Au­(CN)₄] series adopted a 2-fold interpenetrated 3-D cyano-bound framework lacking any weak intermolecular interactions. Despite the tight packing and the presence of intermolecular interactions, these materials exhibited decreased thermal stability over unbound <i>trans-</i>[AuX₂(CN)₂]⁻ in [^<i>n</i>Bu₄N]­[AuX₂(CN)₂]. A significant dielectric constant of up to ε_r = 36 for Ag­[AuCl₂(CN)₂] (1 kHz) and a lower ε_r = 9.6 (1 kHz) for Ag­[Au­(CN)₄] were measured and interpreted in terms of their structures and composition. A systematic analysis of the thermal expansion properties of the M­[AuX₂(CN)₂] series revealed a negative thermal expansion (NTE) component along the cyano-bridged chains with a thermal expansion coefficient (α_CN) of −13.7(11), −14.3(5), and −11.36(18) ppm·K^–1 for Ag­[AuCl₂(CN)₂], Ag­[AuBr₂(CN)₂], and Cu­[AuBr₂(CN)₂], respectively. The Au···X and Ag···X interactions affect the thermal expansion similarly to metallophilic Au···Au interactions in M­[Au­(CN)₂] and AuCN; replacing X = Cl with the larger Br atoms has a less significant effect. A similar analysis for the M­[Au­(CN)₄] series (where the volume thermal expansion coefficient, α_V, is 41(3) and 68.7(19) ppm·K^–1 for M = Ag, Cu, respectively) underscored the significance of the effect of the atomic radius on the flexibility of the framework and, thus, the thermal expansion properties

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 [Ag(μ-L1Clpz)]n (L1Clpz− = 4-chloride-3,5-diisopropyl-1-pyrazolate anion) by the reaction of {[Ag(μ-L1Clpz)]3}2 with (nBu4N)[Ag(CN)2]. The obtained structure was compared with the known hexanuclear silver(I) complex {[Ag(μ-L1Clpz)]3}2. The Ag···Ag distances in [Ag(μ-L1Clpz)]n are slightly shorter than twice Bondi’s van der Waals radius, indicating some Ag···Ag argentophilic interactions. Two Ag–N distances in [Ag(μ-L1Clpz)]n were found: 2.0760(13) and 2.0716(13) Å, and their N–Ag–N bond angles of 180.00(7)° and 179.83(5)° indicate that each silver(I) ion is coordinated by two pyrazolyl nitrogen atoms with an almost linear coordination. Every five pyrazoles point in the same direction to form a 1-D zig-zag structure. Some spectroscopic properties of [Ag(μ-L1Clpz)]n in the solid-state are different from those of {[Ag(μ-L1Clpz)]3}2 (especially in the absorption and emission spectra), presumably attributable to this zig-zag structure having longer but differently arranged intramolecular Ag···Ag interactions of 3.39171(17) Å. This result clearly demonstrates the different physicochemical properties in the solid-state between 1-D coordination polymer and metalacyclic trinuclear (hexanuclear) or tetranuclear silver(I) pyrazolate complexes

Raman Detected Sensing of Volatile Organic Compounds by Vapochromic Cu[AuX₂(CN)₂]₂ (X = Cl, Br) Coordination Polymer Materials

Two vapochromic coordination polymers Cu­[AuX₂(CN)₂]₂ (X = Cl, <b>1</b>; X = Br, <b>2</b>) were prepared and spectroscopically characterized. Exposure of these solid materials to the volatile organic compounds dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, 1,4-dioxane, and ethylene glycol (glycol) resulted in distinct color, and IR and Raman changes. The thermal stability of the analyte-bound materials was assessed by thermogravimetric analysis. Single-crystal structures of Cu­(analyte)₄[AuX₂(CN)₂]₂ (analyte = DMF, DMSO; X = Cl, Br) revealed an isostructural set of 1-D coordination polymer chains, where the analyte molecules were equatorially O-bound to the Cu­(II) centers while axially bound [AuX₂(CN)₂]⁻ units bridged these Cu­(II) centers, while Cu­(glycol)₄[AuBr₂(CN)₂]₂ is molecular, with monodentate glycol units. The structure of Cu₂(OH₂)₄[AuCl₂(CN)₂]₄·4dioxane is a 2-D coordination polymer network with H₂O-bridged Cu­(II) centers and dioxane units hydrogen bonded between the 2-D sheets. The intense Raman <i>v</i>_CN stretches for <b>1</b>, <b>2</b>, and their adducts form distinct, signature patterns. These “antenna” Raman <i>v</i>_CN stretches are an effective means for sensing VOCs, and their characteristic patterns can be used to identify the VOC being detected

Thermal Expansion Behavior of M^I[AuX₂(CN)₂]‑Based Coordination Polymers (M = Ag, Cu; X = CN, Cl, Br)

Two sets of <i>trans-</i>[AuX₂(CN)₂]⁻-based coordination polymer materialsM­[AuX₂(CN)₂] (M = Ag; X = Cl, Br or M = Cu; X = Br) and M­[Au­(CN)₄] (M = Ag, Cu)were synthesized and structurally characterized and their dielectric constants and thermal expansion behavior explored. The M­[AuX₂(CN)₂] series crystallized in a tightly packed, mineral-like structure featuring 1-D <i>trans-</i>[AuX₂(CN)₂]⁻-bridged chains interconnected via a series of intermolecular Au···X and M···X (M = Ag, Cu) interactions. The M­[Au­(CN)₄] series adopted a 2-fold interpenetrated 3-D cyano-bound framework lacking any weak intermolecular interactions. Despite the tight packing and the presence of intermolecular interactions, these materials exhibited decreased thermal stability over unbound <i>trans-</i>[AuX₂(CN)₂]⁻ in [^<i>n</i>Bu₄N]­[AuX₂(CN)₂]. A significant dielectric constant of up to ε_r = 36 for Ag­[AuCl₂(CN)₂] (1 kHz) and a lower ε_r = 9.6 (1 kHz) for Ag­[Au­(CN)₄] were measured and interpreted in terms of their structures and composition. A systematic analysis of the thermal expansion properties of the M­[AuX₂(CN)₂] series revealed a negative thermal expansion (NTE) component along the cyano-bridged chains with a thermal expansion coefficient (α_CN) of −13.7(11), −14.3(5), and −11.36(18) ppm·K^–1 for Ag­[AuCl₂(CN)₂], Ag­[AuBr₂(CN)₂], and Cu­[AuBr₂(CN)₂], respectively. The Au···X and Ag···X interactions affect the thermal expansion similarly to metallophilic Au···Au interactions in M­[Au­(CN)₂] and AuCN; replacing X = Cl with the larger Br atoms has a less significant effect. A similar analysis for the M­[Au­(CN)₄] series (where the volume thermal expansion coefficient, α_V, is 41(3) and 68.7(19) ppm·K^–1 for M = Ag, Cu, respectively) underscored the significance of the effect of the atomic radius on the flexibility of the framework and, thus, the thermal expansion properties

Heterogenous Preparations of Solution-Processable Cobalt Phthalocyanines for Carbon Dioxide Reduction Electrocatalysis

The development and implementation of technology that can capture and transform carbon dioxide (CO2) is of ongoing interest. To that end, the integration of molecular electrocatalysts into devices is appealing because of the desirable features of molecules, such as the ability to modify active sites. Here, we explore how the identity of the aliphatic group in 1,4,8,11,15,18,22,25-octaalkoxyphthalocyanine cobalt(II) affects the catalytic behavior for heterogeneous CO2 reduction electrocatalysis. The alkyl R-groups correspond to n-butoxy, sec-butoxy, and 2-ethylhexoxy. All of the catalysts are soluble in organic solvents and are readily solution-processed. However, the larger 2-ethylhexoxy group showed solution aggregation behavior at concentrations ≥1 mM, and it was, in general, an inferior catalyst. The other two catalysts show comparable maximum currents, but the octa sec-butoxy-bearing catalyst showed larger CO2 reduction rate constants based on foot-of-the-wave analyses. This behavior is hypothesized to be due to the ability of the sec-butoxy groups to eliminate the ability of the alkoxy oxygen to block Co Sites via ligation. CO2 reduction activity is rationalized based on solid-state structures. Cobalt(II) phthalocyanine and its derivatives are known to be good CO2 reduction catalysts, but the results from this work suggest that straightforward incorporation of bulky groups can improve the processability and per site activity by discouraging aggregation

Diamido-Ether Actinide Complexes as Catalysts for the Intramolecular Hydroamination of Aminoalkenes

The synthesis and characterization of a series of new diamido-thorium(IV) and diamido-uranium(IV) halide and alkyl complexes supported by three different diamido-ether ligands are reported. Reaction of ThCl4 center dot 2DME with [(RNSiMe2)(2)O]Li-2 ([(NON)-N-R]Li-2) in DME when R = Bu-t gives [(NON)-N-tBu]- ThCl5Li3 center dot DME (1), when R = (Pr2Ph)-Pr-i in diethyl ether [(NON)-N-iPr2Ph]-ThCl3Li center dot DME (3) is prepared. Reaction of UCl4 with [(NON)-N-iPr2Ph]-Li-2 in diethyl ether gives {[(2NON)-N-iPr-N-Ph]UCl2}(2) (4). Reaction of ThCl4 center dot 2DME with Li-2[((Pr2PhNCH2CH2)-Pr-i)(2)O] ([(NCOCN)-N-iPr2Ph]-Li-2) in DME gives [(NCOCN)-N-iPr2Ph]ThCl2 center dot DME (5). The addition of 2 equiv of LiCH2SiMe3 to 1 and 5 resulted in salt- and base-free [(NON)-N-tBu]Th(CH2SiMe3)(2) (7) and [(NCOCN)-N-iPr2Ph]Th(CH2SiMe3)(2) (9), respectively. Complexes 1, 3, 4, 7, and 9, as well as previously reported {(NON)-N-tBu]UCl2}(2) (2), [(NON)-N-tBu]U(CH2SiMe3)(2) (6), [(NCOCN)-N-iPr2Ph]U(CH2SiMe3)(2) (8) were examined as catalysts for the intramolecular hydroamination of a series of aminoalkenes. Complexes 6-9 were shown to facilitate the formation of 2-methyl-4,4-diphenylpyrrolidine from 2,2-diphenyl-1-amino-4-pentene at room temperature. For 9, this reaction occurs in less than 15 min, while for other diallcyls 6-8, the reaction takes less than 2 h. Dihalides 1 and 2 facilitated the same reaction at 60 degrees C in 4 h, while 3 and 4 showed no activity under the same conditions. Dialkyl complexes 7-9 were examined for further reactivity with different substrates. The uranium dialkyl 8 was more active than 7 and 9 for the cyclization of 2,2-diphenyl-1-amino-5-hexene and 2,2-diphenyl-1-amino-6-heptene, as well as more active in the cyclization of N-methyl-2,2-diphenyl-1-amino-4-pentene, a secondary amine. All three dialkyls became less active when the steric bulk of the gem-substituents was decreased from diphenyl to cyclopentyl; reactivity further decreased when the steric bulk of the substituents was decreased further to hydrogen

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

The new lanthanide–dicyanoaurate coordination polymers [^<i>n</i>Bu₄N]₂­[Ln­(NO₃)₄­Au­(CN)₂] (Ln = Sm, Dy) and Sm­[Au­(CN)₂]₃·3H₂O were prepared and structurally characterized and their luminescence spectra described. The emissions of solid-solutions of [^<i>n</i>Bu₄N]₂­[Ln­(NO₃)₄­Au­(CN)₂] (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 [^<i>n</i>Bu₄N]₂­[Ce_0.4Dy_0.6(NO₃)₄­Au­(CN)₂] and [^<i>n</i>Bu₄N]₂­[Sm_0.75Tb_0.25(NO₃)₄­Au­(CN)₂], and the ternary solid-solutions [^<i>n</i>Bu₄N]₂­[Ce_0.2Sm_0.6­Tb_0.2(NO₃)₄­Au­(CN)₂] and [^<i>n</i>Bu₄N]₂­[Ce_0.33Eu_0.17­Tb_0.5(NO₃)₄­Au­(CN)₂], were prepared and examined in terms of suitability for color-tuning capacity. These results showcase that the emission from the [^<i>n</i>Bu₄N]₂­[Ln­(NO₃)₄­Au­(CN)₂] framework has the capacity to be tuned to extremes corresponding to deep reds (CIE coordinates 0.65, 0.35), greens (0.28, 0.63), and deep blue/violet (0.16, 0.06) as well as white (0.31, 0.33). Conversely, the emission of the Sm­[Au­(CN)₂]₃·3H₂O framework, when doped with the green phosphor Tb­(III), changes only slightly because of the predominantly Au­(I)-based emission and Sm­(III) → Au­(I) energy transfer