Cyanide Research Articles

Dual-Ligand ZIF-8 Bearing the Cyano Group for Efficient and Selective Uranium Capture from Seawater.

Uranium extraction from seawater is a potential technique that will change the world. Adsorption capacity, selectivity, and antibacterial ability for high-performance uranium adsorbents remain the major challenges. In this study, a dual-ligand zeolitic imidazolate framework 8 (ZIF-8) decorated with cyano groups (ZIF-8-CN) is prepared via a facile blend strategy at room temperature. Owing to the abundant mesopores and nitrogen functional groups, ZIF-8-CN shows an extremely high uranium uptake of 1000 mg/g at pH = 6, which is 2.42 times that of pristine ZIF-8. Noteworthily, ZIF-8-CN possesses a 16.2 mg/g uranium adsorption in natural seawater within 28 days, and the distribution coefficient (Kd = 3.25 × 106 mL/g) is far greater than that for other coexisting metal ions, demonstrating a marked preference for uranyl ions. Except for the coordination between uranium and nitrogen in imidazole, the cyano groups provide additional adsorption sites and preferentially bind to uranyl, thereby strengthening the affinity for uranyl. Notably, ZIF-8-CN displays ultrastrong antimicrobial ability against both Escherichia coli and Staphylococcus aureus, which is greatly desired for the scale-up marine tests. Our study demonstrates the high potential of ZIF-8-CN in uranium capture and provides a wide scope for the application of mixed-ligand MOFs.

Metal-free 2D/2D VdW heterojunction fabricated by amorphous covalent triazine frameworks with nitrogen-defect on polymeric carbon nitride towards enhanced photocatalytic performance

The structural design of Van der Waals (VdW) heterojunction photocatalysts has still been a challenging issue, because it usually plays a decisive role in improving photocatalytic performance. Herein, a unique metal-free 2D/2D VdW heterojunction is fabricated by decoration of amorphous covalent triazine frameworks with nitrogen defect (VN-CTFs) on the surface of polymeric carbon nitride (PCN) via a simple acid stripping, self-assembly and heat-treatment process, which demonstrates high-efficiency and stable photocatalytic performance for hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR). The results of experiments reveal that the synergy produced by strong electron-withdrawing effect from cyano groups in VN-CTFs induces charge redistribution at the interface with PCN through π-π interaction of 2D/2D VdW heterojunction, resulting in the formation of built-in electric field, which effectively drives the transfer and separation of photogenerated carriers to enhance the photocatalytic performance. The optimal PCN/VN-CTFs-10 sample exhibits that the average HER rate reaches up to 75.1 and 3.7 times higher than that of onefold VN-CTFs and PCN, respectively, as well as achieves apparent quantum yield (AQY) of 21.5 % at 420 nm and stable operation of 10 cycles totaling 40 h. Meanwhile, CO yields of 28.3 and 2.5 times as high as that of pristine VN-CTFs and PCN, respectively, are also obtained over the optimal PCN/VN-CTFs-10 sample for CO2RR. This work exploits a new structural unit design strategy for developing the metal-free PCN-based VdW heterojunction photocatalysts to boost the photocatalytic performance.

To Fluoresce or Not to Fluoresce: Investigation of Structural and Fluorescence Characteristics of CBI-Dopamine, CBI-Serotonin, and Their Structural Analogs.

Dopamine (DA) and serotonin (5-HT) are neurotransmitters that are vital for proper brain function and are implicated in a wide variety of diseases and disorders. Unfortunately, quantitative analysis of DA and 5-HT is difficult, as they are present at low concentrations in complex biological matrices. The fluorogenic reaction of napththalene-2,3-dicarboxaldehyde (NDA) with a primary amine in the presence of cyanide (CN) creates an N-substituted 1-cyanobenz[f]isoindole (CBI) derivative, whose fluorescence can be sensitively monitored in biological matrices. Given their biological importance, there are surprisingly few reports showing fluorescence of CBI-DA and no prior publications concerning CBI-5-HT. In this work, nuclear magnetic resonance spectroscopy (NMR) was employed to determine the atom connectivity of over 10 CBI-products, including CBI-DA and CBI-5-HT. NMR and fluorescence spectroscopy were applied to CBI-DA, CBI-5-HT, and select structural analogs to determine structural correlations with the observed lack of fluorescence. Experiments with CBI-DA and structural analogs indicated fluorescence was rapidly quenched due to both complexation with the historically employed buffer and oxidation in solution. Fluorescence of CBI-DA was recovered by modifying the derivatization background to prevent complexation and oxidation. In contrast, fluorescence characterization of CBI-5-HT and its structural analogs indicated that 5-HT was acting as a quencher of the CBI-ring. The addition of acid to protonate 5-HT was found to disrupt this interaction and enable the first reported fluorescence detection of CBI-5-HT. In the future, this work will be applied to detect DA and 5-HT in biological systems to gain insight into neurobiological disease states and disorders.

Hydrogen‐Bonded Organic Framework to Upgrade Cycling Stability and Rate Capability of Li‐CO2 Batteries

AbstractElaborately designed multifunctional electrocatalysts capable of promoting Li+ and CO2 transport are essential for upgrading the cycling stability and rate capability of Li‐CO2 batteries. Hydrogen‐bonded organic frameworks (HOFs) with open channels and easily functionalized surfaces hold great potential for applications in efficient cathodes of Li‐CO2 batteries. Herein, a robust HOFS (HOF‐FJU‐1) is introduced for the first time as a co‐catalyst in the cathode material of Li‐CO2 batteries. HOF‐FJU‐1 with cyano groups located periodically in the pore can induce homogeneous deposition of discharge products and accommodate volumetric expansion of discharge products during cycling. Besides, HOF‐FJU‐1 enables effective interaction between Ru0 nanoparticles and cyano groups, thus forming efficient and uniform catalytic sites for CRR/CER. Moreover, HOF‐FJU‐1 with regularly arranged open channels are beneficial for CO2 and Li+ transport, enabling rapid redox kinetic conversion of CO2. Therefore, the HOF‐based Li‐CO2 batteries are capable of stable operation at 400 mA g−1 for 1800 h and maintain a low overpotential of 1.96 V even at high current densities up to 5 A g−1. This work provides valuable guidance for developing multifunctional HOF‐based catalysts to upgrade the longevity and rate capability of Li‐CO2 batteries.

Modification on phthalonitrile containing benzoxazine with hydroxy-terminated polyarylene ether nitrile: Curing reaction and thermomechanical properties

In this work, a kind of BA-ph/BPA-PEN composite film was prepared by modifying phthalonitrile resin containing benzoxazine rings (BA-ph) with hydroxy-terminated polyarylene ether nitrile resin (BPA-PEN). Results show that the introduction of BPA-PEN has a facilitating effect on the polymerization reaction of BA-ph resin, which directly affects the polymerization reaction of the benzoxazine ring and then the cross-linking reaction of the nitrile group. With the increase of BPA-PEN content, a phase reversion structure appeared, which promoted the improvement of the mechanical properties of the system. Meanwhile, the thermal performance of the system was good, and the Td5 of BA-ph (2 h)/10BPA-PEN reached 342.26 °C, which was 43.13 °C higher compared with the pure BA-ph system, and the char yield at 600 °C was 71.57%.

Engineering cyano groups into hydrogen-bonded organic supramolecules with multi redox centers for high-performance Li-ion battery cathode

Bottom-up molecular engineering by rational design has emerged as a promising strategy for exploring advanced organic cathodes. However, directly programming organic moieties into high-performance electro-active materials remains a great challenge. Herein, we design and synthesize a hydrogen-bonded supramolecule (hexaazatrinaphthalene hexacarbonitrile, HATN-6CN) anchored with abundant cyano groups, which ensures structural stability, extended π-conjugated system, and multiple redox active centers. As a result, the HATN-6CN cathode delivers a high specific capacity (297.6 mAh g–1 at 0.5 A g–1, 225.2 mAh g–1 at 5 A g–1) and outstanding long-term cycling performance (191.9 mAh g–1 over 1000 cycles at 5 A g–1 with a capacity retention of 85.2 %). Moreover, the charge storage mechanisms, structural evolution, and reversibility during the redox process of HATN-6CN were systematically investigated. This work offers a feasible and promising avenue for bottom-up molecular engineering of organic electrodes by rational design.

CN− and NH2− co-decorated graphdiynes: A theoretical investigation

In this work, the cyano (CN−) and amino (NH2−) groups are used to co-decorate the monolayer graphdiyne (GDY) resulting in two new GDY derivative systems (i.e., A1C2- and A2C1-GDYs). The structural stabilities of these two systems are carefully verified. Due to the local dipole moments introduced by the CN− and NH2− groups, as well as the breaking central symmetry, the corresponding mechanical, piezoelectric, and electronic features, even the electrical transport properties, are significantly altered comparing with the pristine GDY, F-GDY, and CN-GDY systems. The predicted band gaps of A1C2- and A2C1-GDYs are around 1.25 eV and 1.33 eV at the PBE level, respectively, which are obviously larger than that of the pristine GDT monolayer (0.53 eV at the same theoretical level). There are also observable negative piezoelectric effects in both new GDY derivatives due to the change of the local dipole moment under strains. Moreover, the negative electrical conductivity constants σxy are revealed in both co-decorated monolayer GDY systems at certain chemical potentials, indicating the switch of the major carrier types according to the Hall effect. This theoretical study not only expands the GDY family, but also provides a new opportunity for switching carrier types in 2D materials using the in-plane electric field.

ZnO-poly(acrylonitrile) composite films with improved piezoelectric properties for energy harvesting and sensing applications

Piezoelectric nanogenerators are one of the possible solutions for generating power in milliwatts for various mobility applications. They can also be utilized as tactile sensors. Since poly(acrylonitrile) (PAN) has a greater dipole moment (3.5 D) than poly (vinylidene fluoride) (PVDF), it has a strong potential for use as piezoelectric nanogenerators and pressure sensors. However, due to strong dipole-dipole repulsion, the nitrile groups are difficult to align in a zig-zag configuration resulting in reduced ability of the system to convert mechanical energy into electrical energy. To address this issue, we have incorporated ZnO nanoparticles (ZnP) and ZnO nanowires (ZnW) in PAN films. Due to the strong interaction of ZnO nanostructures with PAN, the dipole-dipole repulsion reduces resulting in increased zigzag conformation of PAN. Compared to ZnP, ZnW was found to show better alignment of PAN nitrile groups and faster relaxation of dipoles after removal of stress. Without any external poling, PAN, ZnP-PAN, and ZnW-PAN films based piezoelectric nanogenerators could generate 27.6, 79.3 and 86.3 mW/m2 of power, respectively. The incorporation of 5 wt% ZnP and ZnW also significantly improved the pressure sensitivities of the devices to 0.9 fFPa−1 and 1.1 fFPa−1, respectively, as compared to 0.1 fFPa−1 for pristine PAN film.

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity.

Tetrazole-based easily synthesizable fluorogenic probes have been developed that can form self-assembled nanostructures in the aqueous medium. Though the compounds could achieve detection of cyanide ions in apolar solvents, such as, THF, significant interference was observed from other basic anions, such as F-, AcO-, H2PO4-, etc. On the other hand, a highly specific response was observed for CN- ions in the aqueous medium. However, the sensitivity was so poor that it could hardly be useful for real-life sample analysis. Interestingly, the co-assembly of such probe molecules with hydroxyethyl-anchored amphoteric surfactants could drastically improve the sensitivity toward CN- ions in water without dampening their excellent selectivity. Also, it was observed that the degree of fluorescence response for CN- ions depends on the nature of the polyaromatic scaffolds (naphthyl vs anthracenyl), the nature of the surfactant assembly (micelle vs vesicle), etc. The mechanistic investigation indicates the hydrogen bonding interaction between the tetrazole -NH group and cyanide ions in the aqueous medium, which can effectively change the electronics of the tetrazole unit, resulting in alteration in the extent of charge transfer interaction. Then, the biocompatible composite materials (dye-surfactant assemblies at different ratios) were tested for antituberculosis activity. Fortunately, in a few cases, the compositions were found to be as effective as the commercially available antituberculosis drug, ethambutol.

Enzymatic properties of a non-classical aldoxime dehydratase capable of producing alkyl and arylalkyl nitriles.

Nitriles are of significant interest in the flavor and fragrance industries with potential application in cosmetics due to their higher stability than analogous aldehydes. However, the traditional methods to prepare nitriles need toxic reagents and hash conditions. This work aimed to develop a chemoenzymatic strategy to synthesize nitriles from natural aldehydes with aldoxime as the intermediate. A non-classical aldoxime dehydratase (Oxd) was discovered from the fungus Aspergillus ibericus (OxdAsp) to catalyze the dehydration of aldoximes to corresponding nitriles under mild conditions. The amino acid sequence of OxdAsp exhibits an approximately 20% identity with bacterial Oxds. OxdAsp contains a heme prosthetic group bound with the axial H287 in the catalytic pocket. The structure models of OxdAsp with substrates suggest that its catalytic triad is Y138-R141-E192, which is different from the classically bacterial Oxds of His-Arg-Ser/Thr. The catalytic mechanism of OxdAsp was proposed based on the mutagenesis of key residues. The hydroxyl group of the substrate is fixed by E192 to increase its basicity. Y138 acts as a general acid-based catalyst, and its phenolic proton is polarized by the adjacent R141. The protonated Y138 would donate a proton to the hydroxyl group of the substrate and eliminate a water molecule from aldoxime to produce nitrile. The recombinant OxdAsp can efficiently dehydrate citronellaloxime and cinnamaldoxime to citronellyl nitrile and cinnamonitrile in aqueous media, which are applied as fragrance ingredients in the food and cosmetic fields. KEY POINTS: • A novel aldoxime dehydratase from the Aspergillus genus was first characterized as a heme-binding protein. • The catalytic mechanism was predicted based on the molecular interactions of the catalytic pocket with the substrate. • A chemoenzymatic strategy was developed to synthesize nitriles from natural aldehydes with aldoxime as the intermediate.

Designing a high-potential metal-free viologen-based redox polymer for effective wiring of FAD-dependent glucose dehydrogenase

Metal-free organic redox mediators, whose redox potentials can be tuned according to the intended enzyme system and application, are emerging as alternative mediators for the design of improved enzyme-based biosensors and biofuel cells. We report a novel class of metal-free redox polymer containing a polymer-tethered dicyano viologen mediator for the immobilization of FAD-dependent glucose dehydrogenase (FAD-GDH) on graphite electrodes. Incorporation of strong electron-withdrawing cyano groups to the viologen moiety ensures the formation of high potential viologen-based redox polymer with an envisaged pH-independent redox potential close to 50 mV (vs Ag /AgCl/ 3 M KCl) and a negligible impact on oxygen reduction. The bioelectrode comprising of newly designed redox polymer and FAD-GDH showed enhanced electrocatalytic activity in the presence of glucose, confirming effective wiring of FAD-GDH, if embedded within the redox polymer.

The isocyanide SN2 reaction

The SN2 nucleophilic substitution reaction is a vital organic transformation used for drug and natural product synthesis. Nucleophiles like cyanide, oxygen, nitrogen, sulfur, or phosphorous replace halogens or sulfonyl esters, forming new bonds. Isocyanides exhibit unique C-centered lone pair σ and π* orbitals, enabling diverse radical and multicomponent reactions. Despite this, their nucleophilic potential in SN2 reactions remains unexplored. We have uncovered that isocyanides act as versatile nucleophiles in SN2 reactions with alkyl halides. This yields highly substituted secondary amides through in situ nitrilium ion hydrolysis introducing an alternative bond break compared to classical amide synthesis. This novel 3-component process accommodates various isocyanide and electrophile structures, functional groups, scalability, late-stage drug modifications, and complex compound synthesis. This reaction greatly expands chemical diversity, nearly doubling the classical amid coupling’s chemical space. Notably, the isocyanide nucleophile presents an unconventional Umpolung amide carbanion synthon (R-NHC(-) = O), an alternative to classical amide couplings.

Microwave activation in [FeCl3·6H2O–TfOH] - catalysed reaction of binor-s with organic nitriles

An efficient catalytic system, consisting of 20 mol % of FeCl3·6H2O and 20 mol % of trifluoromethanesulfonic acid, for amidation of binor-S in a solution of toluene using organic nitriles under microwave synthesis was developed. Typically the reaction proceeds at 100°C in 15 min.

In Situ Forming Gel Polymer Electrolyte for High Energy-Density Lithium Metal Batteries.

In situ forming gel polymer electrolyte (GPE) is one of the most feasible ways to improve the safety and cycle performances of lithium metal batteries with high energy density. However, most of the in situ formed GPEs are not compatible with high-voltage cathode materials. Here, this work provides a novel strategy to in situ form GPE based on the mechanism of Ritter reaction. The Ritter reaction in liquid electrolyte has the advantage of appropriate reaction temperature and no additional additives. The polymer chains are cross-linked by amide groups with the formation of GPE with superior electrochemical properties. The GPE has high ionic conductivity (1.84 mS cm-1 ), wide electrochemical stability window (>5.25V) and high lithium ion transference number (≈0.78), compatible with high-voltage cathode materials. The Li|LiNi0.6 Co0.2 Mn0.2 O2 batteries with in situ formed GPE show excellent long-term cycle stability (93.4%, 300 cycles). The density functional theory calculation and X-ray photoelectron spectroscopyresults verify that the amide and nitrile groups are beneficial for stabilizing cathode structure and promoting uniform Li deposition on Li anode. Furthermore, the in situ formed GPE exhibits excellent electrochemical performance in Graphite|LiMn2 O4 and Graphite|LiNi0.5 Co0.2 Mn0.3 O2 pouch batteries. This approach is adaptable to current battery technologies, which will be sure to promote the development of high energy-density lithium-ion batteries.

Concurrent determination of cyanide and thiocyanate in human and swine antemortem and postmortem blood by high-performance liquid chromatography-tandem mass spectrometry.

Cyanide (in the form of cyanide anion (CN-) or hydrogen cyanide (HCN), inclusively represented as CN) can be a rapidly acting and deadly poison, but it is also a common chemical component of a variety of natural and anthropogenic substances. The main mechanism of acute CN toxicity is based on blocking terminal electron transfer by inhibiting cytochrome c oxidase, resulting in cellular hypoxia, cytotoxic anoxia, and potential death. Due to the well-established link between blood CN concentrations and the manifestation of symptoms, the determination of blood concentration of CN, along with the major metabolite, thiocyanate (SCN-), is critical. Because currently there is no method of analysis available for the simultaneous detection of CN and SCN- from blood, a sensitive method for the simultaneous analysis of CN and SCN- from human ante- and postmortem blood via liquid chromatography-tandem MS analysis was developed. For this method, sample preparation for CN involved active microdiffusion with subsequent chemical modification using naphthalene-2,3-dicarboxaldehyde (NDA) and taurine (i.e., the capture solution). Preparation for SCN- was accomplished via protein precipitation and monobromobimane (MBB) modification. The method produced good sensitivity for CN with antemortem limit of detection (LODs) of 219 nM and 605 nM for CN and SCN-, respectively, and postmortem LODs of 352 nM and 509 nM. The dynamic ranges of the method were 5-500µM and 10-500µM in ante- and postmortem blood, respectively. In addition, the method produced good accuracy (100 ± 15%) and precision (≤ 15.2% relative standard deviation). The method was able to detect elevated levels of CN and SCN- in both antemortem (N = 5) and postmortem (N = 4) blood samples from CN-exposed swine compared to nonexposed swine.

Biosynthesized silver nanoparticles based on bitter orange bloom extract and its application for the determination of cyanide ion in environmental samples

Developing new methods for detecting and determining toxic anions is an essential parameter from waste sources for industrial and environmental scientists. This study presented, a new process for the biosynthesis of silver nanoparticles (AgNPs) based on the bitter orange bloom extract and its potential as a highly selective and sensitive chemosensor for detecting and quantifying cyanide ions. These biosynthesized AgNPs have a sharp and intense surface plasmon resonance (SPR) peak around 405 nm. AgNPs with a yellow color can be changed to colorless in the presence of a certain concentration of cyanide ions due to forming a new adduct between AgNPs and cyanide ions. Hence, the SPR intensity of AgNPs decreases, and the color of the solution becomes colorless. The sensor response to cyanide ions was linear in the concentration range of 49.7 to 1208.8 nM, and the detection limit was equal to 7.9 nM. As an applicable alternative, this assay is highly capable of qualitative and quantitative measurements of cyanide ions in the waste and toxic samples.

Research advances of SERS analysis method based on silent region molecules for food safety detection.

Food safety is a critical issue that is closely related to people's health and safety. As a simple, rapid, and sensitive detection technique, surface-enhanced Raman scattering (SERS) technology has significant potential for food safety detection. Recently, researchers have shown a growing interest in utilizing silent region molecules for SERS analysis. These molecules exhibit significant Raman scattering peaks in the cellular Raman silent region between 1800 and 2800 cm-1 avoiding overlapping with the SERS spectrum of biological matrices in the range 600-1800 cm-1, which could effectively circumvent matrix effects and improve the SERS accuracy. In this review, the application of silent region molecules-based SERS analytical technique for food safety detection is introduced, detection strategies including label-free detection and labeled detection are discussed, and recent applications of SERS analysis technology based on molecules containing alkyne and nitrile groups, as well as Prussian blue (PB) in the detection of pesticides, mycotoxins, metal ions, and foodborne pathogens are highlighted. This review aims to draw the attention to thesilent region molecules-based SERS analytical technique and toprovide theoretical support for its further applications in food safety detection.

Anthraquinone Based Sensors for the Selective Detection of Cyanide Ion with Turn on Fluorescence with Logic Gate & Real Sample Applications.

In recent years, there is an increasing interest in finding better and more efficient ways to detect CN- ions. Most of the anthraquinone-based probes show less fluorescenceThis paper presents the design and synthesis of a new anthraquinone based imine probe with good colorimetric sensing property and fluorescent turn on behavior towardCN- ion. Herein, we report a receptor with both colorimetric and fluorescent enhancement of cyanide ion in DMSO medium is synthesized. The synthesized receptor shows an immediate color change from orange to pink when cyanide is added; and it can be readily observed visually due to the presence of diverse p-conjugated systems in the receptor. These studies wereconfirmed by UV-Visible, PL studies, DFT, HRMS and 1H NMR titration. Moreover, this receptor shows 1:1 stoichiometry and micromolar detection limit. Further the receptor wasapplied to areal sample in finger millet (Eleusine Coracana) to detect the presence of cyanide ion. Moreover, the receptor is applicable towardINHIBITION, IMPLICATION logic gates with two input systems.

The Influence of Positional Isomerism of Terminal Alkyl Chains on Mesomorphic and Photophysical Behavior of Unsymmetric α-cyanostilbene-based Tetracatenars.

Two series of unsymmetric α-cyanostilbene-based tetracatenars containing three hexadecyl chains at one end and one alkyl chain with varying lengths at the other end were prepared by using Suzuki coupling and Knoevenagel reactions. These tetracatenars with the terminal three hexadecyl chains, which are adjacent to the cyano group are non-mesogens, whereas the isomers with one alkyl chain, which is adjacent to the cyano group display transition from non-mesogens to monotropic hexagonal columnar liquid crystal upon elongation of the alkyl chain. This transition could be attributed to that the three hexadecyl chains which are adjacent to the cyano group decrease the interactions between π-conjugated rigid cores, hindering the formation of mesophase. In addition, weak slovatochromism implies weak ICT in both series tetracatenars. Both series isomers exhibit distinct AIE characteristics attributing to the presence of α-cyanostilbene, which could induce stereoisomerism and restricted intermolecular rotation in the aggregated state. Different mechanochromism behaviors could be achieved due to the positional isomerism of terminal alkyl chains. Therefore, tuning the position of terminal alkyl chains could give rise to distinct changes in the molecular aggregate, which provides a scheme to build multifunctional materials with diverse potentials.

Synthesis, crystal structure and thermal behavior of tetra-kis-(3-cyano-pyridine N-oxide-κO)bis-(thio-cyanato-κN)cobalt(II), which shows strong pseudo-symmetry.

The title compound, [Co(SCN)2(C6H4N2O)4], was prepared by the reaction of cobalt(II)thio-cyanate with 3-cyano-pyridine N-oxide in ethanol. In the crystal, the cobalt(II) cations are octa-hedrally coordinated by two terminal N-bonded thio-cyanate anions and four O-bonded 3-cyano-pyridine N-oxide coligands, forming discrete complexes that are located on centers of inversion, hence forming trans-CoN2O4 octa-hedra. The structure refinement was performed in the monoclinic space group P21/n, for which a potential lattice translation and new symmetry elements with a fit of 100% is suggested. The structure can easily be refined in the space group I2/m, where the complexes have 2/m symmetry. However, nearly all of the reflections that violate the centering are observed with significant intensity and the refinement in P21/n leads to significantly lower R(F) values (0.027 versus 0.033). Moreover, in I2/m much larger components of the anisotropic displacement parameters are observed and therefore, the crystal structure is presented in the primitive unit cell. IR investigations confirm that the anionic ligands are only terminally bonded and that the cyano group is not involved in the metal coordination. PXRD investigations show that a pure crystalline phase has been obtained and measurements using simultaneously thermogravimetry and differential thermoanalysis reveal that the compound decomposes in an exothermic reaction upon heating, without the formation of a coligand-deficient inter-mediate phase.