Reaction Of NiCl2 Research Articles

A new binuclear Ni(II) complex, an effective A3-coupling catalyst in solvent-free condition

A newly binuclear nickel(II) complex, [Ni2(en)4(ox)](ClO4)2 (1) (where en = ethylenediamine, and ox = oxalate), has been isolated from a reaction of NiCl2·6H2O, ethylenediamine, ammonium oxalate and sodium perchlorate in water and its crystal structure has been determined by X-ray crystallography and infra-red techniques. Compound 1 was successfully employed to promote the one-pot reaction of aldehydes, amines and acetylenes for the construction of corresponding propargylamines under solvent-free media with fine yields. Further studies reveal this catalytic system can be refreshed and used again in five runs.

Synthesis, characterization, solution chemistry and anticancer activity of [NiCl2(Ph2P–N(R)–PPh2)] (R = 2-CH2Py, CH2Ph and p-tol) complexes

In this work three Ni2+ complexes with general formula [NiCl2(Ph2P–N(R)–PPh2)], R = 2-CH2Py (Py = pyridine) – 1, CH2Ph (Ph = phenyl) – 2 and p-tol (p-tol = p-tolyl) – 3, were synthesized and characterized. These complexes were obtained in high yield by the reaction of NiCl2.6H2O and the corresponding diphenylphosphinoamine ligand (Ph2P–N(R)–PPh2) in CH2Cl2/MeOH (1:1) solution, at room temperature (∼25 °C), and characterized by 1H and 31P {1H} NMR, vibrational spectroscopy in the infrared region, electronic spectroscopy in the UV–Vis regions, elemental analysis (%C, %H, %N) and single-crystal X-ray diffraction. The solution chemistry was studied in CDCl3/dmso-d6 (dimethylsulfoxide) or neat dmso-d6 using complex 2 as a model. The complexes were evaluated as cytotoxic agents against two cancer cells lines, A549 (lung cancer cells), B16F10 (melanoma cells) and the health cells HaCaT (human epithelial keratinocytes).

Crystal Structure, Theoretical Analyses and Thermodynamic Properties of a Ni(II) Complex Based on ONO Donor Tridentate Acylhydrazone

A novel complex [Ni(C10H8O5N3)2]and#183;H2Oand#183;(CH3OH) (1) (C10H9O5N3= 2-[(4-nitro- benzoyl)-hydrazone]-propionic acid) has been prepared by reaction of NiCl2 with C10H9O5N3 in mixed solvent of methanol and water. The Ni(II) complex in octahedral geometry was characterized by elemental analysis and X-ray single crystal diffraction. Isothermal titration calorimetry (ITC) was performed to observe the reactions between Ni(II) and C10H9O5N3 in methanol solvents. The results showed that the binding constant (Ka), enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy change (ΔG) of the system are 5.2and#215;105, -11.82 kJand#183;mol-1, 69.78 Jand#183;mol-1and#183;K-1 and -32.62 kJand#183;mol-1, respectively. In addition, the structure was optimized and frontier molecular orbital (FMO) of (1) were analyzed by B3LYP and HF methods with 6-31g level.

Synthesis, crystal structure and Hirshfeld surface analysis of hexa-aqua-nickel(II) bis-(4-hy-droxy-benzoate) dihydrate.

The title compound, [Ni(H2O)6](PHB)2·2H2O (1) (PHB = 4-hy-droxy-benzoate, C7H5O3), was obtained by the reaction of NiCl2, 4-hy-droxy-benzoic acid (PHBA) and mono-ethano-lamine in aqueous ethanol solution. The NiII ion is coordinated by six water mol-ecules and is located on an inversion center. The outer coordination sphere in the asymmetric unit comprises one PHB anion and one water mol-ecule, i.e. the compound is a salt and a hydrate consisting of three components. In the crystal, the components are packed into an inter-molecular network stabilized by O-H⋯O hydrogen bonds. A comprehensive Hirshfeld surface analysis was carried out to investigate the inter-molecular inter-actions in detail.

Novel Dithiolene Nickel Complex Catalysts for Electrochemical Hydrogen Evolution Reaction for Hydrogen Production in Nonaqueous and Aqueous Solutions

Three molecular catalysts based on mononuclear nickel(II) complexes with square planar geometries, [BzPy]2[Ni(mnt)2] (1), [BzPy]2[Ni(i-mnt)2] (2), and [BzPy]2[Ni(tdas)2] (3) (BzPy = benzyl pyridinium) are synthesized by the reaction of NiCl2∙6H2O, [BzPy]Br, and Na2(mnt)/Na2(i-mnt)/Na2(tdas) (mnt = 1,2-dicyanoethylene-1,2-dithiolate for (1), i-mnt = 2,2-dicyanoethylene-1,1-dithiolate for (2), and tdas = 1,2,5-thiadiazole-3,4-dithiolate for (3)), respectively. The structures and compositions of these three catalysts are characterized by XRD, elemental analysis, FT-IR, and ESI-MS. The electrochemical properties and the corresponding catalytic activities of these three catalysts are studied by cyclic voltammetry. The controlled-potential electrolysis with gas chromatography analysis confirms the hydrogen production with a turnover frequency (TOF) of 116.89, 165.51, and 189.16 moles of H2 per mole of catalyst per hour at a potential of − 0.99 V (versus SHE) in acetonitrile solutions containing the catalysts, respectively. In a neutral buffer solution, these three molecular catalysts exhibit a TOF of 411.85, 488.76, and 555.06 mol of H2 per mole of catalyst per hour at a potential of − 0.49 V (versus SHE), respectively, indicating that Complex 3 constitutes the better active catalyst than Complexes 1 and 2. For fundamental understanding, a catalytic HER mechanism is also proposed.Graphical abstract

An infinite chain, {[Ni(tn)2]3[Fe(CN)4(μ-CN)2]2}n, a new catalyst for electrochemical-driven water splitting and photochemical-driven hydrogen evolution from water under blue light

A new catalyst for both water reduction and oxidation, based on an infinite chain, {[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n, is formed by the reaction of NiCl2, 1,3-propanediamine (tn) and K3 [Fe(CN)6]. {[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n can electro-catalyze hydrogen evolution from a neutral aqueous buffer (pH 7.0) with a turnover frequency (TOF) of 1561 mol of hydrogen per mole of catalyst per hour (H2/mol catalyst/h) at an overpotential (OP) of 837 mV {[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n also can electro-catalyze O2 production from water with a TOF of ∼45 mol O2 (mol cat)−1s−1 at an OP of 591 mV. Under blue light (λ = 469 nm), together with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, {[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n can photo-catalyze hydrogen generation from an aqueous buffer (pH 4.0) with a turnover number (TON) of 11,450 mol H2 per mole of catalyst (mol of H2 (mol of cat)−1) during 10 h irradiation. The average of apparent quantum yield (AQY) is as high as 40.96% during 10 h irradiation. Studies indicate that {[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n exists in two forms: a cyano-bridged chain ({[Ni(tn)2]3 [Fe(CN)4 (μ-CN)2]2}n) in solid, and a salt ([Ni(tn)2]3 [Fe(CN)6]2) in aqueous media; Catalytic reaction occurs on the nickel center of [Ni(tn)2]2+, and the introduction of [Fe(CN)6]3- can improve the catalytic efficiency of [Ni(tn)2]2+ for H2 or O2 generation. We hope these findings can afford a new method for the design of catalysts for both water reduction and oxidation.

A nickel(II) complex of 2,6-pyridinedicarboxylic acid ion, an efficient electro-catalyst for both hydrogen evolution and oxidation

A new electrocatalyst based on a nickel complex, [Ni(HL)2], is designed and provided by the reaction of NiCl2 with 2,6-pyridinedicarboxylic acid (H2L) in our group. Electrochemical investigations show that [Ni(HL)2] can electro-catalyze hydrogen evolution from acetic acid with a rate constant of 3454 M−2 s−1. [Ni(HL)2] also can electro-catalyze hydrogen oxidation with a rate constant of 2.047 × 104 M−2 s−1. The carboxyl group of [Ni(HL)2] may play critical roles in the catalytic hydrogen evolution and oxidation reactions. Moreover, the introduction of an electron-withdrawing group, -Cl at the pyridine of H2L leads to a decrease in the catalytic activity for hydrogen generation, and [Ni(HL)2] shows a more efficient activity than [Ni(HL-Cl)2] (H2L-Cl: 4-chloro-2,6-pyridinedicarboxylic acid). These findings can afford a new ideal for the design of electrocatalysts for both H2 evolution and H2 oxidation.

A nickel complex of 2,2-dicyanoethylene-1,1-dithiolate, a catalyst for electrochemical and photochemical driven hydrogen evolution

The reaction of NiCl2, K2(i-mnt) (i-mnt2−= 2,2-dicyanoethylene-1,1-dithiolate) and 1-benzyl-4-amino-pyridinium bromide [BzPyNH2]Br affords a nickel complex, [BzPyNH2]2[Ni(i-mnt)2], a molecular catalyst for electrochemical and photochemical driven hydrogen evolution. As an electrocatalyst, [BzPyNH2]2[Ni(i-mnt)2] can electrocatalyze hydrogen generation from a neutral buffer with a turnover frequency (TOF) of 556 (±3) mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 837.6 mV. As a photocatalyst, combining with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, [BzPyNH2]2[Ni(i-mnt)2] photocatalyzes hydrogen evolution in heterogeneous environments with a turnover number (TON) of 18420 (±5) mol H2 per mol of catalyst during 60 h irradiation. The highest apparent quantum yield (AQY) is ∼10% at 469 nm. Several chemical and physical methods are employed to understand catalytic procedures for H2 production.

Crystal exploring, Hirshfeld surface analysis, and properties of 4′‐(furan‐2‐yl)‐2,2′:6′,2″‐terpyridine complexes of nickel (II): New precursors for the synthesis of nanoparticles

A series of mono‐ and bis‐terpyridine complexes of nickel (II) based on the 4′‐(furan‐2‐yl)‐2,2′:6′,2″‐terpyridine (ftpy) have been synthesized and structurally characterized using elemental analysis, infrared spectroscopy, and single crystal X‐ray diffraction. The reaction of NiCl2•6H2O with ftpy has been resulted in the formation of new bis‐terpyridine complex [Ni (ftpy)2](PF6)•2H2O (1). The new complex [Ni (ftpy)2](PF6)2 (2), obtained during the crystallization of 1 in methanol, was characterized using X‐ray crystallography, which shows that six nitrogen atoms from terpyridine ligands occupy the coordination sites around the Ni (II) in a distorted octahedral geometry. On the other hand, the reaction of NiCl2•6H2O with ftpy in a 1:2 or 1:1 mole ratio in methanol in the presence of KSCN affords two new thiocyanato complexes [Ni (ftpy)2](SCN)2•2H2O (3) and [Ni (ftpy)(NCS)2(H2O)]•2H2O (4), respectively. The crystal structure of 3 reveals that nickel (II) is hexa‐coordinated in a distorted octahedral geometry NiN6 involving six atoms of two ftpy ligand; the ftpy ligands are perpendicular to each other. The new complex [Ni (ftpy)(NCS)2(DMSO)]•DMSO (5) is obtained during the crystallization of 4 in DMSO. The crystal structure of 5 reveals that the nickel (II) is hexa‐coordinated by three nitrogen atoms of ftpy, two NCS−, a DMSO in a slightly distorted octahedral geometry. The X–H (XH, C, N, O) bond interactions control the arrangement of the supramolecular 3D framework. Hirshfeld surface analyses and two‐dimensional fingerprint plot reveal that the main interactions are H–H contacts for 2, 3, and 5, which comprise 34.1%, 37.2%, and 34.6%, respectively. Thermal decomposition of the coordination complexes led to the formation of Ni, NiO, and Ni2P2O7 nanoparticles (NPs). The resulting NPs were fully characterized by powder XRD, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and energy‐dispersive X‐ray spectroscopy (EDX). The formation of these NPs indicates the role of the precursor complexes and counterion. Our results indicate that the NPs with the smaller size could be obtained at calcination temperature of 600 °C. Thermal and luminescent properties of complexes have been discussed in detail.

One pot synthesis and spectral characterization of 5-Substitutedfuran-2-carbaldehyde N4-cyclohexyl thiosemicarbazones and their Ni(II) complexes

In this work, the synthesis of thiosemicarbazones (I-V) was carried out using one pot method, multicomponent and catalyst-free reaction of cyclohexyl isothiocyanate, hydrazine monohydrate and 5-substituted-2-furancarbaldehydes in good yields. The chemical structures of 5-substituted-2-furancarbaldehyde thiosemicarbazones were eludicated using UV‐Vis, IR, 1H NMR, 13C NMR, mass spectra, and elemental analysis. Also, the reaction of NiCl2.6H2O with thiosemicarbazones in 1:2 molar ratio by refluxing gave the nickel (II) complexes (Ia-Va) as binuclear and their structures characterized by UV-Vis, IR, and elemental analysis.

Dinickel(II) complexes with pyridine-substituted bis(triazolylmethyl)amine ligands: Structures and magnetic properties

The coordination behavior of the newly prepared bis(triazolylmethyl)amine-type ligands bis[(1-R-1H-1,2,3-triazol-4-yl)methyl]amine [R = CH2Ph (L1), CH2-2-pyridyl (L2)] and 1-(1-benzyl-1H-1,2,3-triazol-4-yl)-N-((1-(pyridin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)methanamine (L3) toward NiII ions was investigated. The reaction of NiCl2·6H2O with the benzyl-substituted bis(triazolylmethyl)amine ligand L1 afforded the mononuclear NiII complex Ni(L1)2Cl2 (1). On the other hand, dinuclear NiII complexes, [Ni2(L2)2Cl2]Cl2 (2) and [Ni2(L3)2Cl2]Cl2 (3), were obtained when NiCl2·6H2O was reacted with the pyridine-substituted ligands L2 and L3, respectively. Single-crystal X-ray analysis revealed that the two octahedral NiII centers in 2 and 3 are bridged by two triazole rings through nitrogen donors to generate the dinuclear complexes with a syn arrangement. Meanwhile, treatment of Ni(NO3)2 with L2 afforded the related dinickel(II) complex [Ni2(L2)2(NO3)2](NO3)2 (2′), in which two non-bridging triazole rings and two nitrate ions are positioned in an anti arrangement. Complexes 2 and 3 showed antiferromagnetic coupling between the two NiII centers (S = 1), with J values following the trend: 2′ > 2 > 3.

Dinickel(Ii) Complexes with Pyridine-Substituted Bis(Triazolylmethyl)Amine Ligands: Structures and Magnetic Properties

Coordination behavior of newly prepared bis(triazolylmethyl)amine-type ligands, bis[(1-R-1H-1,2,3-triazol-4-yl)methyl]amine [R = CH2Ph (L1), CH2-2-pyridyl (L2)] and 1-(1-Benzyl-1H-1,2,3-triazol-4-yl)-N-((1-(pyridin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)methanamine (L3), toward NiII ions was investigated. The reaction of NiCl2·6H2O with the benzyl-substituted bis(triazolylmethyl)amine ligand L1 afforded the mononuclear NiII complex Ni(L1)2Cl2 (1). On the other hand, the dinuclear NiII complexes, [Ni2(L2)2Cl2]Cl2 (2) and [Ni2(L3)2Cl2]Cl2 (3), were obtained when NiCl2·6H2O was reacted with the pyridine-substituted ligands, L2 and L3, respectively. Single-crystal X-ray analysis revealed that two octahedral NiII centers in 2 and 3 are bridged by two triazole rings through nitrogen donors to generate the dinuclear complexes with a syn arrangement. Meanwhile, treatment of Ni(NO3)2 with L2 afforded the related dinickel(II) complex, [Ni2(L2)2(NO3)2](NO3)2 (2'), in which two non-bridging triazole rings and two nitrate ions were positioned in an anti arrangement. Complexes 2 and 3 showed the antiferromagnetic coupling between two NiII centers (S = 1), with J values following the trend: 2' > 2 > 3.

Nickel(II), Copper(II) and Palladium(II) Complexes with Bis-Semicarbazide Hexaazamacrocycles: Redox-Noninnocent Behavior and Catalytic Activity in Oxidation and C-C Coupling Reactions.

Nickel(II), copper(II), and palladium(II) complexes MLH, where M = Ni (1), Cu (2), Pd (3), and MLOMe, where M = Ni (4), Cu (5), Pd (6), have been prepared by reactions of NiCl2·6H2O, Cu(OAc)2·H2O, and PdCl2(MeCN)2 with 14-membered bis-semicarbazide hexaazamacrocycles H2LH and H2LOMe in dimethylformamide (DMF). The compounds were characterized by elemental analysis, ESI mass spectrometry, IR, UV-vis, and 1D (1H, 13C) and 2D (1H-1H COSY, 1H-1H TOCSY, 1H-1H NOESY, 1H-13C HSQC, 1H-13C HMBC) NMR spectra (1, 3, 4, and 6), and X-ray diffraction (2, 4-6). The complexes with MIIN4 coordination environment have S = 0, 1/2, 0 ground states for Ni, Cu, and Pd, respectively. The electrochemical behavior of 1-6 was investigated in detail. The electronic structures of 1e-oxidized species were studied by EPR, UV-vis-NIR spectroelectrochemistry, and DFT calculations, indicating the redox-noninnocent behavior of the ligands. Compounds 1-6 were tested in the oxidation of styrene and C-C coupling (Henry and Knoevenagel condensations). Compounds 2 and 5 selectively catalyze the microwave-assisted oxidation of neat styrene to benzaldehyde (up to 88% yield), whereas the 1 and 4 catalytic systems afforded up to 99% β-nitroethanol yield with an appreciable diastereoselectivity toward the formation of the anti isomer.

Generation of a Ni3 Phosphinidene Cluster from the Ni(0) Synthon, Ni(η3-CPh3)2

Reaction of NiCl2 in THF with 2 equiv of Li(CPh3) at −25 °C results in formation of Ni(η3-CPh3)2 (1) in moderate yield. Complex 1 was fully characterized, which included analysis by X-ray crystallo...

Binuclear Nickel(II) Complex Containing 6-Methyl-2,2'-bipyridine and Chloride Ligands: Synthesis, Characterization, Thermal Analyses, and Crystal Structure Determination

A new binuclear complex of [{NiCl(6-mbipy)}2(μ-Cl)2] (1) was prepared from the reaction of NiCl2.6H2O and 6-methyl-2,2'-bipyridine (6-mbipy) in a mixture of methanol and acetonitrile. Suitable crystals of 1 for X-ray diffraction measurement were obtained by slow evaporation of the resulted green solution at room temperature. Complex 1 was characterized by spectral methods (IR, UV–Vis, and luminescence), elemental analysis (CHN), and single-crystal X-ray diffraction. The structure of 1 is centrosymmetric binuclear complex and each Ni(II) cation is five-coordinated in a slightly distorted square-pyramidal configuration. In this binuclear complex, the Ni…Ni distance is 3.533(1)A. Furthermore, the luminescence emission of the title complex was blue-shifted and is stronger than that of free 6-methyl-2,2'-bipyridine ligand. Thermal stabilities of this complex was also studied by thermogravimetric analysis.

Structural Diversity of Nickel and Manganese Chloride Complexes with Pyridin-2-One.

Reactions of NiCl2·6H2O and pyridin-2-one (C5H5NO = Hhp) afforded novel molecular complexes, i.e., mononuclear [NiCl2(Hhp)4] (1), dinuclear [NiCl2(Hhp)(H2O)2]2.2Hhp (3) and [Ni2Cl4(Hhp)5]·2MeCN (4), and an ionic complex [Ni(Hhp)6]Cl2 (2). Single-crystal X-ray analyses revealed two modes of Hhp ligation in these complexes: a monodentate coordination of carbonyl oxygen in all of them and an additional µ2-oxygen bridging coordination in the dinuclear complex 4. Three bridging molecules of Hhp span two nickel(II) ions in 4 with a 2.9802 (5) Å separation of the metal ions. Complex 3 is a chlorido-bridged nickel dimer with a planar Ni2(µ-Cl)2 framework. Hydrogen bonds and parallel stacking arrangements of the Hhp molecules govern the connectivity patterns in the crystals, resulting in 1D structures in 1 and 5 or 2D in 3. A single manganese compound [MnCl2(Hhp)4] (5), isostructural to 1, was isolated under the similar conditions. This is in contrast to four nickel(II) chloride complexes with Hhp. Thermal analyses proved the stability of complexes 1 and 3 in argon up to 145 °C and 100 °C, respectively. The decomposition of 1 and 3 yielded nickel in argon and nickel(II) oxide in air at 800 °C.

The effect of oxidation state of metal on electrochemical and photochemical driven hydrogen evolution catalyzed by nickel complexes of maleonitriledithiolate ligands

Two nickel-based catalysts, TBA2[NiII(mnt)2] 1 and TBA[NiIII(mnt)2] 2 are formed by the reactions of NiCl2·6H2O, Na2(mnt), and tetra-n-butylammoniumbromide (TBABr) without or with iodine (I2) (mnt = 2,2-dicyanoethylene-1,1-dithiolate), respectively. Under an overpotential (OP) of 941.6 mV, complexes 1 and 2 can electrocatalyze hydrogen evolution from acetic acid with a turnover frequency (TOF) of 36.3 and 148.31 mol H2/mol catalyst/h, respectively. Under blue light (λ max = 469 nm), 1 or 2, together with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, can produce hydrogen with a turnover number (TON) of 7760 and 17,570 moles of H2 per mole of catalyst during 35 h irradiation, respectively. The average value of apparent quantum yield (AQY) is ∼9.2% (complex 1) and 28% (complex 2), respectively. The results indicate that the nickel(III) complex has a better active activity for hydrogen production than the nickel(II) species.

Formation of a carbonato bridged Ni4-complex by atmospheric CO2 fixation: Crystal structure and magnetic properties

Reaction of NiCl2·6H2O with a simple N2O donor tridentate reduced Schiff base ligand, 2-[(3-methylamino-propylamino)-methyl]-4-nitro-phenol (HL) yielded a tetranuclear complex, [Ni4L4Cl2(µ4-CO3)(CH3CN)2]·0.5CH3CN·H2O (1) which was structurally characterized. Complex 1 is an example of atmospheric CO2 fixation model with uniqueness in a new µ4-κ2:κ2:ƞ1:ƞ1-carbonato coordination mode to Ni(II). Involvement of this type of NNO donor ligands for the synthesis of carbonato bridged polynuclear compounds by spontaneous atmospheric CO2 fixation is very rare. All Ni(II) ions are in octahedral environment in 1 with phenoxido and hexadentate µ4-carbonato bridging. Variable temperature magnetic measurements showed overall antiferromagnetic coupling between Ni(II) centers with J1 = −60.32 cm−1, J2 = −19.52 cm−1, J3 = 2.6 cm−1 and J4 = 3.3 cm−1. The magnetic behavior of the complex has been explained considering the carbonato and phenoxido bridging angles.

Crystal structure and DFT analyses of a pentacoordinated PCP pincer nickel(II) complex.

The reaction of NiCl2 with 1,3-bis[(diphenylphosphanyl)methyl]hexahydropyrimidine in the presence of 2,6-dimethylphenyl isocyanide and KPF6 afforded a new pentacoordinated PCP pincer NiII complex, namely {1,3-bis[(diphenylphosphanyl)methyl]hexahydropyrimidin-2-yl-κN2}(2,6-dimethylphenyl isocyanide-κC)nickel(II) hexafluoridophosphate 0.70-hydrate, [Ni(C9H9N)(C30H30ClN2P2)]PF6·0.7H2O or [NiCl{C(NCH2PPh2)2(CH2)3-κ3P,C,P'}(Xylyl-NC)]PF6·0.7H2O, in very good yield. Its X-ray structure showed a distorted square-pyramidal geometry and the compound does not undergo dissociation in solution, as shown by variable-temperature NMR and UV-Vis studies. Density functional theory (DFT) calculations provided an insight into the bonding; the nickel dsp2-hybridized orbitals form the basal plane and the nearly pure p orbital forms the axial bond. This is consistent with the NBO (natural bond orbital) analysis of analogous nickel(II) complexes.

Synthesis and Crystal Structure of Nickel(II) and Zinc(II) Complexes with O-Propylxanthate and N, N, N′,N′-Tetramethylethylenediamine

The reaction of NiCl2·6H2O or Zn(CH3CO2)·2H2O with potassium O-propylxanthate (KS2COC3H7) and N, N, N′,N′-tetramethylethylenediamine (tmeda) affords monomeric complexes of the formula [M(S2COC3H7)2(tmeda)] (M = Ni(II) 1; Zn(II) 2). Both complexes are characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy. Complexes 1 and 2 crystalize in monoclinic P21/c and I2/a space groups, respectively. Each metal center is ligated by four S atoms from xanthate ligands and two N atoms from tmeda in a distorted octahedral geometry.