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The complex containing iron(II), 2,6-bis(pyrazol-3-yl)pyridine (3-bpp) as ligand, and tetracyanonickelate as counter anion has been synthesized and characterized. The characterization data suggest the corresponding formula of [Fe(3-bpp)2][Ni(CN)4]·4H2O. Meanwhile, the SEM–EDX analysis image confirms the existence of all elements contained in the complex except the hydrogen atom. The infrared spectra exhibit vibration bands of the functional groups of 3-bpp ligand and [Ni(CN)4]−1 anion. From magnetic property measurement, the complex's molar magnetic susceptibility (XMT) value is 2.65 emu mol−1 K at 300 K, which contains about 75% high-spin state of the Fe(II) complex. Upon lowering the temperature, the XMT value gradually decreases around 1.37 emu mol−1 K at 13 K. It decreases sharply to about 0.73 emu mol−1 K at 2 K. These values reveal that Fe(II) complex is in the low-spin (LS) state. As a result, the complex exhibited spin-crossover characteristics of gradual transition without thermal hysteresis, and the transition temperature occurred below room temperature with a transition temperature (T1/2) close to 140 K. The spin crossover property of the complex is supported by a thermochromic reversible color change from red-brown at room temperature to dark brown on cooling in liquid nitrogen associated with the high-spin to low-spin transition.

In the title molecular salt, (C10H10N3)2[Ni(CN)4], the dihedral angle between the pyridine rings in the cation is 1.92 (13)° and the complete anion is generated by a crystallographic centre of symmetry. An intramolecular N—H...N hydrogen bond occurs in the cation, which closes an S(6) ring. In the crystal, the components are linked by N—H...N and weak C—H...N hydrogen bonds, which generate chains propagating in the [101] direction. Weak aromatic π–π stacking interactions are also observed. A Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contact types in the crystal packing are N...H/H...N, C...H/H...C and H...H with contributions of 37.2, 28.3 and 21.9%, respectively.

Two new complexes [Cu(bcen)Ni(CN)4]2 (1) and [Ni(bcen)Ni(CN)4] (2) where bcen is 4,7-diazadecanediamide, were synthesized by reaction of equimolar amounts of M(NO3)2 (M = Cu and Ni), bcen ligand and K2[Ni(CN)4]. Single-crystal X-ray diffraction analysis of compound 1, shows that the bcen ligand acts as a tridentate chelate, coordinating to the Cu(II) ion via the two nitrogen atoms of the amine groups and one oxygen atom of one amide group, and the other amide unit is left uncoordinated. The coordination geometry around the Cu(II) ions is five coordinate with a distorted square pyramid geometry, comprising two nitrogen atoms and one oxygen atom belonging to the bcen ligand and two nitrogen atoms of the cyano groups of two Ni(CN)42– units. The distance between the copper ion and the amide oxygen of the dangling arm of an adjacent tetranuclear species is within the expected range for an axial Cu–O bond, and hence suggests that the amide oxygen of an adjacent tetranuclear complex may weakly coordinate to the copper ion in an axial position. These contacts link the tetranuclear species into infinite chain polymers.

Tetracyanonickelate (TCN)-based metal-organic frameworks (MOFs) show great potential in electrochemical applications such as supercapacitors due to their layered morphology and tunable structure. This study reports on improved electrochemical performance of exfoliated manganese tetracyanonickelate (Mn-TCN) nanosheets produced by the heat-assisted liquid-phase exfoliation (LPE) technique. The structural change was confirmed by the Raman frequency shift of the C≡N band from 2177 to 2182 cm -1 and increased band gap from 3.15 to 4.33 eV in the exfoliated phase. Statistical distribution obtained from atomic force microscopy (AFM) shows that 50% of the nanosheets are single-to-four-layered and have an average lateral size of ∼240 nm 2 and thickness of ∼1.2-4.8 nm. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) patterns suggest that the material maintains its crystallinity after exfoliation. It exhibits an almost 6-fold improvement in specific capacitance (from 13.0 to 72.5 F g -1 ) measured at a scan rate of 5 mV s -1 in 1 M KOH solution. Galvanostatic charge-discharge (GCD) measurement shows a capacity enhancement from ∼18 F g -1 in the bulk phase to ∼45 F g -1 in the exfoliated phase at a current density of 1 A g -1 . Bulk crystals exhibit an increasing trend of capacitance retention by ∼125% over 1000 charge-discharge cycles attributed to electrochemical exfoliation. Electrochemical impedance spectroscopy (EIS) demonstrates a 5-fold reduction in the total equivalent series resistance (ESR) from 4864 Ω (bulk) to 1089 Ω (exfoliated). The enhanced storage capacity in the exfoliated phase results from the combined effect of the electrochemical double-layer charge storage mechanism at the nanosheet-electrolyte interface and the Faradic process characteristic of the pseudocapacitive charge storage behavior.

Two new complexes [Cu(bcen)Ni(CN)4]2 (1) and [Ni(bcen)Ni(CN)4] (2) where been is 4,7-diazadecanediamide, were synthesized by reaction of equimolar amounts of M(NO3)2 (M = Cu and Ni), bcen ligand and K2[Ni(CN)4]. Single-crystal X-ray diffraction analysis of compound 1, shows that the bcen ligand acts as a tridentate chelate, coordinating to the Cu(II) ion via the two nitrogen atoms of the amine groups and one oxygen atom of one amide group, and the other amide unit is left uncoordinated. The coordination geometry around the Cu(II) ions is five coordinate with a distorted square pyramid geometry, comprising two nitrogen atoms and one oxygen atom belonging to the bcen ligand and two nitrogen atoms of the cyano groups of two Ni(CN)42- units. The distance between the copper ion and the amide oxygen of the dangling arm of an adjacent tetranuclear species is within the expected range for an axial Cu-O bond, and hence suggests that the amide oxygen of an adjacent tetranuclear complex may weakly coordinate to the copper ion in an axial position. These contacts link the tetranuclear species into infinite chain polymers. [ABSTRACT FROM AUTHOR]

In this study, clathrate of 4-pyridinecarboxaldehyde tetracyanonickel-dioxane, given by the formula M(4-Pyridinecarboxaldehyde)Ni(CN)4 nG (m = Ni, Cd and G = 1,4-dioxane), is obtained for the first time through chemical methods. The FT-IR spectroscopic data in the region of (3000-400) cm-1 was recorded and the IR vibrational modes frequencies were given and explained in detail. The spectral analyzes results of the newly synthesized clathrate of 4-pyridinecarboxaldehyde tetracyanonickel- dioxane suggests that these clathrates are new examples of the Hofmann-type dioxane clathrates. In our study, the Hofmann-type dioxane clathrates formed by bounding electrons of nitrogen-donor atom of pyridine ring and electrons of oxygen-donor atom of aldehyde group (-CH=O) of 4-pyridinecarboxaldehyde ligand molecule to transition metal atoms consist of the corrugated |M--Ni(CN)4|∞ polymeric layers which are held in parallel through the chain of (--M--4PCA--M--). [ABSTRACT FROM AUTHOR]

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The first synthesis of benzonitrile tetracyanonickelate complexes, represented by the general formula M(benzonitrile)Ni(CN) (M = Ni, Zn, Cd, and Hg), is reported. Fourier transform infrared spectroscopy and Raman spectroscopic data in the region of 4,000-400 cm are presented, and the vibrational frequencies are assigned and explained in detail. The thermal behavior of these complexes was also investigated by thermogravimetric analysis, differential thermal analysis, and derivative thermal gravimetric analysis. The spectral and thermal analysis results of the newly synthesized complexes suggest that these complexes are new examples of Hofmann-type complexes. The spectral data obtained show that the complexes consist of |M-Ni(CN)| polymeric layers with the ligand (benzonitrile) molecules bound to metal through the N-donor atom of the cyanide group. [ABSTRACT FROM AUTHOR]

FT-IR spectra of the ligands, 1,5-pentanedithiol (PDT) and 1,8-octanedithiol (ODT), with their complexes with the divalent transition metal ions Co(II) and Cd(II) are reported for the first time in the 400-4000 cm-1 range. Furthermore the thermal behaviors of M(PDT)Ni(CN)4 and M(ODT)Ni(CN)4 (M = Co and Cd) compounds were studied by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and derivative thermal gravimetric analysis (DTG) in the range of (25-250) °C and their XRD patterns and elemental analyses were presented. The spectral and thermal features suggest that the compounds are similar in structure to the Hofmann-type complexes with infinite polymeric layers formed with Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. ions bridged by ML+2 cations. [ABSTRACT FROM AUTHOR]

New Hofmann-type tetracyanoaqua 2-methylpyrazine metal (II) nickelate (II) benzene clathrates, [M(H2O)(2 mpz)Ni(CN)4]·C6H6 (where 2 mpz = 2-methylpyrazine (C5H6N2); M=Mn(II) or Cd(II); C6H6 = benzene) have been prepared in powder form and characterized by infrared and Raman spectroscopy. Thermal behaviors of these compounds are followed using thermo-gravimetric analysis and differential thermal analysis (DTA) techniques. The spectral features suggest that these compounds are similar in structure to the Hofmann-type two-dimensional coordination polymer compounds. The metal (II) ions are coordinated by aqua, 2-methylpyrazine ligands, and four N atoms of CN groups in the tetracyanonickelate ions. A detailed analysis of the vibrational spectra indicates the presence of hydrogen bonding between the ligand molecules of the host lattices and π electrons of the benzene molecule. The spectral data show that the positions of almost all bands due to the guest molecule remain practically unchanged on enclathration. The C, H, N, and metal analyses were carried out for all the compounds and were found to fit the proposed formulas well. The experimental results are in agreement with the proposed formulas. [ABSTRACT FROM AUTHOR]

Abstract: Four new Hofmann–3-phenylpropylamine (3PPA) type complexes with chemical formulae M(3PPA)2Ni(CN)4 (M=Ni, Co, Cd, and Pd) have been prepared and their vibrational spectra are reported in the region of 4000–60cm−1. The vibrational bands arising from 3PPA ligand molecule, the polymeric sheet and metal–ligand bands of the compounds are assigned. The thermal behaviour of these complexes is also provided using the DTA and TGA along with the magnetic susceptibility data. The results indicate that the monodentate 3PPA ligand molecule bonds to the metal atom of |M–Ni(CN)4|∞ polymeric layers and hence the compounds are similar in structure to Hofmann-type complexes. [Copyright &y& Elsevier]

In this study, Hofmann type M(C6H16N2)Ni(CN) 4·nG (M= Ni, Cd or Co; G= Toluene, Biphenyl or Aniline; n=the number of guest) host-guest compounds were obtained chemically. The infrared spectra of these compounds were recorded in the spectroscopic region of 4000 cm-1-400 cm-1, and the vibrational wave numbers of ligand molecule, Ni(CN)4 2- ion and guest molecules were determined. In addition, elemental analysis of the compounds were performed and the results were found to support given formula. The results indicated that the structure of the host-guest compounds was similar to those of Hofmann-type compounds, ligand molecule diaminohexane was coordinated to M metal atom through its nitrogen, the guest molecules were trapped in the structural cavities between the sheets. [ABSTRACT FROM AUTHOR]

Abstract: 4-Aminopyrimidine tetracyanonickelate, M(4APM)2Ni(CN)4 {where M=Mn, Co, Ni, Zn or Cd; 4APM=4-aminopyrimidine}, coordination polymer compounds have been prepared for the first time and their FT-IR (400–4000cm−1) and FT-Raman (70–4000cm−1) spectra are reported. 4APM is coordinated to M(II) through one of the pyrimidine ring nitrogen atoms as a monodentate ligand; the amino group is not involved in the complex formation. Vibrational bands arising from both 4APM and the Ni(CN)4 group, were assigned. The effect of coordination on 4APM vibrational wavenumbers is analysed by comparison with isostructural compounds. [Copyright &y& Elsevier]

Abstract: In this study, the Raman and far-IR spectra of the two dimensional coordination polymer compounds, M(PZA)2Ni(CN)4 {where M=Mn, Ni, Zn or Cd; PZA=pyrazinamide} and mid-IR spectrum of Zn(PZA)2Ni(CN)4 were reported for the first time. Far-IR spectroscopic study allowed us to make correction in the bonding mode of PZA. PZA molecules are found to involve coordination through one of the pyrazine ring nitrogen atoms. The spectral features suggest that the compounds are similar in structure to the Hofmann type two dimensional coordination polymer compounds, formed with ions bridged by cations. Vibrational bands originated from both PZA and Ni(CN)4 group were assigned. [Copyright &y& Elsevier]

c.m. kao, s.h. li, y.l. chen and s.c. chen. 2005. The ability of Azotobacter vinelandii, a N2-fixing bacterium, to biodegrade tetracyanonickelate (TCN) was evaluated. The amounts of TCN were measured spectrophotometrically. Ammonia was determined colorimetrically by the indophenol method. The produced methane from TCN conversion by A. vinelandii was detected by gas chromatography. Results showed that A. vinelandii was able to biodegrade 1 mmol l−1 of TCN. Ammonia and methane were detected during the process of TCN degradation. Effects of exogenous nitrogen sources on TCN degradation were addressed in this study. Results revealed that the addition of ammonia (1, 5 and 10 mmol l−1) into the reaction mixtures caused decrease of TCN degradation rate during a 24-h incubation period. This inhibition was also observed when nitrite (5 and 10 mmol l−1) was added, whereas TCN degradation still proceeded after the addition of nitrate at the same concentrations. Furthermore, the rate of TCN utilization was strikingly enhanced when 0·8% of glucose was added. Azotobacter vinelandii can degrade 1 mmol l−1 of TCN into ammonia and methane. However, the inhibitory effects of exogenous ammonia and nitrite on TCN degradation by this bacterium were found in this study. This is the first report defining the capability of A. vinelandii to degrade TCN. This bacterium might have potential value in applied strategies for removing metal-cyano wastes. Furthermore, these findings would be helpful in designing a practical system inoculated with A. vinelandii for the treatment of TCN. [ABSTRACT FROM AUTHOR]

Abstract: The Raman spectra of the two dimensional layered polymer compounds, M(2APM)2M′(CN)4 {where M=Mn or Cd; and M′=Ni or Pt; 2APM=2-aminopyrimidine} are reported in the 70–4000cm−1 region. Vibrational data suggests that compounds are similar in structure to the Hofmann type two dimensional coordination polymer compounds, formed with ions bridged by cations. 2-Aminopyrimidine was coordinated to M(II) through one of the nitrogen atom of its heterocycle ring. Vibrational assignments are given for the bands arising from the tetracyanometallate layers and coordinated 2APM. [Copyright &y& Elsevier]

In this study, fourier transform-infrared FT-IR spectra of M(iso)2Ni(CN)4 (where M = Cd, Zn, Ni, or Cu; iso = isonicotinamide; abbreviated to M–Ni-iso) and Cd(iso)2X2 (where X = Cl, Br, or I) complexes are reported in the 4000–400 cm−1 range. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. The proposed structure of tetracyanonickelate complexes consists of polymeric layers of |M–Ni(CN)4|∞ with the isonicotinamide molecules bound directly to the metal (M). [ABSTRACT FROM AUTHOR]

M(PZA)2Ni(CN)4 {where M=Mn, Co, Fe, Ni or Cd; PZA=pyrazinamide} complexes have been prepared for the first time and their FT-IR spectra are reported in the 400–4000 cm−1 region. The spectral features suggest that the compounds are similar in structure to the Hofmann type two dimensional coordination polymer compounds, formed with Ni(CN)4−2 ions bridged by M(PZA)2+2 cations. PZA is coordinated to M(II) through the oxygen atom of the carbonyl group. [Copyright &y& Elsevier]

A new yeast strain capable of degrading free and metallocyanides was isolated from coke-plant wastewater. The isolated strain designated MCN2 was identified as Cryptococcus humicolus by 26S rDNA sequencing and phylogenetic analysis. During growth of the isolate with KCN as a sole nitrogen source, formamide and formic acid were found as transient intermediates by [13C]nuclear magnetic resonance analysis and ammonia accumulated as a final product in the culture medium. The strain MCN2 could degrade high concentrations of tetracyanonickelate (II) (K2Ni(CN)4, TCN) up to 65 mM CN within 60 h when a sufficient amount of glucose was supplied as a carbon source. The maximal degradation rate of TCN was 2.5 mM CN h−1 at the initial concentration of 51 mM CN. [Copyright &y& Elsevier]

The coordination polymeric compounds, M(2APM)2Ni(CN)4 (where M=Mn, Co, Ni or Cd; 2APM=2-aminopyrimidine) have been prepared for the first time and their FT-IR spectra are reported in the 400–4000 cm−1 region. The spectral features suggest that the compounds are similar in structure to the Hofmann type two dimensional coordination polymeric compounds, formed with Ni(CN)4−2 ions bridged by M(2APM)2+2 cations. 2APM is coordinated to M(II) through one of the pyrimidine ring nitrogen atoms; the amino group is not involved in the complex formation. The coordination effect on the 2APM vibrational wavenumbers is analysed. [Copyright &y& Elsevier]

Infrared spectra of MLNi (CN)4 [M=Mn, Fe, Co, Ni, Zn or Cd and L= Divalent metal of p-Aminobenzoic Acid or ABA (Mg)] are reported. Their structure consists of polymeric layers of [M-Ni(CN)4]a with the divalent metal of p-aminobenzoic acid [ABA(Mg)] molecules bound directly to the metal (M). [ABSTRACT FROM AUTHOR]

• Tetracyanonickelate (II)/KOH was fabricated on nickel foam using a dip-coating method. • The novel electrode exhibited a high sensitivity of −1.6 µA ppm−1 cm−2. • The detection range of the electrode was from 1 to 50 ppm with high linearity. • Chlorobenzene gas was monitored during its electrochemical degradation process. The stable molecular structure of chlorobenzene makes it difficult to detect at room temperature. In this study, potassium hydroxide and tetracyanonickelate (II) ([Ni(CN) 4 ]2−) fabricated nickel foam was synthesized using a dip-coating method and monitored the chlorobenzene in the gas phase. The morphology and structure of the as-prepared sample were characterized by X-ray diffraction, field-emission scanning electron microscopy, dispersive energy spectrum, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The gas-sensing test showed that the presence of KOH enhanced the sensing performance of the tetracyanonickelate (II) layer. The KOH/tetracyanonickelate (II)-fabricated nickel foam showed a good response to low chlorobenzene concentrations ranging from 1 to 50 ppm with −0.0016 mA ppm−1 cm−2 sensitivity. In contrast, KOH and the tetracyanonickelate (II) separately fabricated nickel foam showed no response to chlorobenzene. The response time of the sensor was approximately 250 s. The mechanism for the enhanced sensing of tetracyanonickelate (II) was discussed. The sensor stability test confirmed the good stability of the sensor in measuring the chlorobenzene gas concentration. The developed electrochemical gas flow sensor effectively monitored the exit chlorobenzene gas during the electrochemical degradation process; the concentration was calculated using a calibration plot with 98.5% accuracy. [ABSTRACT FROM AUTHOR]

Infrared spectra of M(1,8-diaminooctane)Ni(CN)4⋅G (M= Co, Ni or Cd; G=benzene, chlorobenzene, toluene, p-xylene, naphthalene or biphenyl) compounds are reported. The 1,8-diaminooctane molecules in the host permit the inclusion of bulky guest molecules. The spectral features suggest that the compounds are similar in structure to the Hofmann-type clathrates. [ABSTRACT FROM AUTHOR]

A simple and sensitive conductometric method for the determination of 2-24 mg of pindolol and propranolol hydrochlorides using ammonium reineckate and potassium tetracyanonickelate in an ethanol-water mixture is described. The effect of the solvent ratio, reagent concentration, time and temperature on the shape of the titration curve is studied. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method is indicated by the excellent recovery (98.2-101.2%) and the precision is supported by the low standard deviation value < 0.10. The sensitivity of the proposed method is discussed and the results are compared with the pharmacopoeial non-aqueous titration method. [ABSTRACT FROM AUTHOR]

Abstract: New Hofmann type clathrates in the form of M(4-Chpy)2Ni(CN)4·nG [where 4-Chpy=4-(3-cyclohexen-1-yl)pyridine, G=1,4-dioxane and M=Ni, Co] were prepared in powder form and their infrared spectra are reported in the range of 4000–400cm−1. The spectral features point out that the compounds are similar in structure to the Hofmann type clathrates. Regarding host–guest interaction, the interaction for the present compounds is weak resulting from the large cavity of the host structure. [Copyright &y& Elsevier]