NiII Atom Research Articles

Synthesis, crystal structure study, characterization, and DFT investigation of a new nickel(II) complex, [dihomopiperazine nickel (II)] sulfate tetrahydrate

A new nickel (II) complex [NiL2](H2O)4(SO4), where L = 1,4-diazepane, has been synthesized by interaction between nickel sulfate and 1,4-diazepane. This complex crystallizes in the Pmcn orthorhombic unit cell with parameters a = 9.173(2) Å, b = 11.691(2) Å, c = 17.015(2) Å, V = 1824.9(5) Å3, and Z = 4. It possesses a mononuclear structure in which the central NiII atom is coordinated by four N atoms from two 1,4-diazepane ligands in a distorted square-planar geometry. In the crystal, the anions [SO4]2−, the cations [NiL2]2+, and the water molecules are held together by H-bonding to form a 2D supramolecular structure. Differential scanning calorimetry (DSC) results showed that this compound undergoes a reversible order–disorder phase transition at 486 K with a hysteresis of 32 K. In addition, electrical conductivity measurements showed that the complex has a conductivity value of 4.15 10−4 Ω−1cm−1 at 390 K. The Density Functional Theory (DFT) study results qualitatively supported the experimental data obtained by X-ray diffraction and thermogravimetric analysis (TGA).

Mer-Bis(quinoline-2-carboxaldehyde 4-ethyl-thio-semicarbazonato)nickel(II) methanol 0.33-solvate 0.67-hydrate.

In the title compound, [Ni(C13H13N4S)2]·0.33CH3OH·0.67H2O, the NiII atom is coordinated by two tridentate quinoline-2-carboxaldehyde 4-ethyl-thio-semi-car-ba-zonate ligands in a distorted octa-hedral shape. At 100 K, the crystal symmetry is monoclinic (space group P21/n). A mixture of water and methanol crystallizes with the title complex, and one of the ethyl groups in the coordinating ligands is disordered over two positions, with an occupancy ratio of 58:42. There is inter-molecular hydrogen bonding between the solvent mol-ecules and the amine and thiol-ate groups in the ligands. No other significant inter-actions are present in the crystal packing.

Synthesis and crystal structure of (NH4)[Ni3(HAsO4)(AsO4)(OH)2

The title compound, ammonium trinickel(II) hydrogen arsenate arsenate di-hydroxide, was synthesized under hydro-thermal conditions. Its crystal structure is isotypic with that of K[Cu3(HAsO4)(AsO4)(OH)2] and is characterized by pseudo-hexa-gonal (001) 2 ∞[Ni3As2O18/3(OH)6/3O1/1(OH)1/1]- layers formed from vertex- and edge-sharing [NiO4(OH)2] octa-hedra and [AsO3.5(OH)0.5] tetra-hedra as the building units. The hydrogen atom of the OH group shows occupational disorder and was refined with a site occupation factor of 1/2, indicating the equal presence of [HAsO4]2- and [AsO4]3- groups. Strong asymmetric hydrogen bonds between symmetry-related (O,OH) groups of the arsenate units [O⋯O = 2.588 (18) Å] as well as hydrogen bonds accepted by these (O,OH) groups from OH groups bonded to the NiII atoms [O⋯O = 2.848 (12) Å] link adjacent layers. Additional consolidation of the packing is achieved through N-H⋯O hydrogen bonds from the ammonium ion, which is sandwiched between adjacent layers [N⋯O = 2.930 (7) Å] although the H atoms could not be located in the present study. The presence of the pseudo-hexa-gonal 2 ∞[Ni3As2O18/3(OH)6/3O1/1(OH)1/1]- layers may be the reason for the systematic threefold twinning of (NH4)[Ni3(HAsO4)(AsO4)(OH)2] crystals. Significant overlaps of the reflections of the respective twin domains complicated the structure solution and refinement.

Bis[S-octyl 3-(2-methyl-propyl-idene)di-thio-carb-az-ato-κ2N3,S]nickel(II).

The central NiII atom in the title complex, [Ni(C13H25N2S2)2], is located on an inversion center and adopts a roughly square-planar coordination environment defined by two chelating N,S donor sets of two symmetry-related ligands in a trans configuration. The Ni-N and Ni-S bond lenghts are 1.9193 (14) and 2.1788 (5) Å, respectively, with a chelating N-Ni-S bond angle of 86.05 (4)°. These data are compared with those measured for similar di-thio-carbazato ligands that bear n-octyl or n-hexyl alkyl chains. Slight differences are observed with respect to the phenyl-ethyl-idene derivative where the ligands are bound cis relative to one another.

Synthesis, crystal structure and Hirshfeld surface analysis of diaquabis(o-phenylenediamine-κ2 N,N′)nickel(II) naphthalene-1,5-disulfonate

The reaction of o-phenylenediamine (OPD), sodium naphthalene1,5-disulfonate (Na2NDS) and nickel sulfate in an ethanol–water mixture yielded the title compound, [Ni(OPD)2(H2O)2]·NDS or [Ni(C6H8N2)2(H2O)2](C10H6O6S2). This salt consists of a complex [Ni(OPD)2(H2O)2]2+ cation with two bidentate OPD ligands and trans aqua ligands, and a non-coordinating NDS2– anion, which is the double-deprotonated form of H2NDS. The NiII atom is situated at a center of inversion and exhibits a slightly tetragonally distorted {O2N4} octahedral coordination environment, with four shorter equatorial Ni—N bonds [2.0775 (17) and 2.0924 (18) Å] and a longer axial Ni—O bond [2.1381 (17) Å]. The OPD ligand is located about an inversion center and is nearly coplanar with the NiN4 plane [dihedral angle 0.95 (9)°]. In the crystal, the cations and anions are connected by charge-assisted intermolecular N—H...O and O—H...O hydrogen-bonding interactions into the tri-periodic network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (44.1%), O...H/H...O (34.3%), C...H/H...C (14.8%) C...C (6.5%) (involving the cations) and O...H/H...O (50%), H...H (25%), C...H/H...C (15.3%), C...C (8.2%) (involving the anions) interactions.

A nickel(II) complex with an unsymmetrical tetra-dentate chelating ligand derived from pyridine-2,6-dicarbaldehyde and 2-amino-thio-phenol.

[(2-{[6-(1,3-Benzo-thia-zol-2-yl)pyridin-2-yl]carbonyl-aza-nid-yl}phen-yl)sulf-anido]nickel(II), [Ni(C19H11N3OS2)], crystallizes in the centrosymmetric monoclinic space group P21/n with one mol-ecule in the asymmetric unit. The expected ligand, a bis-Schiff base derived from pyridine-2,6-dicarbaldehyde and 2-amino-thio-phenol, had modified in situ in a both unexpected and unsymmetrical fashion. One arm had cyclized to form a benzo[d]thia-zol-2-yl functionality, while the imine linkage of the second arm had oxidized to an amide group. The geometry about the central NiII atom is distorted square-planar N3S. The mol-ecules form supra-molecular face-to-face dimers via rather strong π-π stacking inter-actions, with these dimers then linked into chains via pairwise C-H⋯O inter-actions.

Crystal structure and Hirshfeld surface analysis of bis-{(Z)-N'-[(E)-(furan-2-yl)methyl-idene]carbamo-hydrazono-thio-ato}nickel(II) methanol disolvate.

In the title complex, [Ni(C6H6N3OS)2]·2CH3OH, the NiII atom is coordinated by the S and N atoms of two N'-[(Z)-(furan-2-yl)methyl-idene]carbamohydrazono-thioic acid ligands in a distorted square-planar geometry. The two mutual ligands bound to NiII are also connected by C-H⋯S inter-actions, while the H atoms of the NH2 group of the ligands form R 4 4(8) motifs with the O atoms of the solvent ethyl alcohol mol-ecules. At the same time, the OH groups of the solvent ethyl alcohol mol-ecules form parallel layers to the (011) plane by the O-H⋯N inter-actions with the ligand N atom that is not bonded to the NiII atom.. The layers are connected by van der Waals inter-actions. A Hirshfeld surface analysis indicates that the most important contacts are H⋯H (37.7%), C⋯H/H⋯C (14.6%), O⋯H/H⋯O (11.5%) and S⋯H/H⋯S (10.6%).

Study of the Counter Cation Effects on the Supramolecular Structure and Electronic Properties of a Dianionic Oxamate-Based {NiII2} Helicate.

Herein, we describe the synthesis, crystal structure, and electronic properties of {[K2(dmso)(H2O)5][Ni2(H2mpba)3]·dmso·2H2O}n (1) and [Ni(H2O)6][Ni2(H2mpba)3]·3CH3OH·4H2O (2) [dmso = dimethyl sulfoxide; CH3OH = methanol; and H4mpba = 1,3-phenylenebis(oxamic acid)] bearing the [Ni2(H2mpba)3]2- helicate, hereafter referred to as {NiII2}. SHAPE software calculations indicate that the coordination geometry of all the NiII atoms in 1 and 2 is a distorted octahedron (Oh) whereas the coordination environments for K1 and K2 atoms in 1 are Snub disphenoid J84 (D2d) and distorted octahedron (Oh), respectively. The {NiII2} helicate in 1 is connected by K+ counter cations yielding a 2D coordination network with sql topology. In contrast to 1, the electroneutrality of the triple-stranded [Ni2(H2mpba)3] 2- dinuclear motif in 2 is achieved by a [Ni(H2O)6]2+ complex cation, where the three neighboring {NiII2} units interact in a supramolecular fashion through four R22(10) homosynthons yielding a 2D array. Voltammetric measurements reveal that both compounds are redox active (with the NiII/NiI pair being mediated by OH- ions) but with differences in formal potentials that reflect changes in the energy levels of molecular orbitals. The NiII ions from the helicate and the counter-ion (complex cation) in 2 can be reversibly reduced, resulting in the highest faradaic current intensities. The redox reactions in 1 also occur in an alkaline medium but at higher formal potentials. The connection of the helicate with the K+ counter cation has an impact on the energy levels of the molecular orbitals; this experimental behavior was further supported by X-ray absorption near-edge spectroscopy (XANES) experiments and computational calculations.

Photocatalytic precise hydrogenation of furfural over ultrathin Pt/NiMg-MOF-74 nanosheets: Synergistic effect of surface optimized NiII sites and Pt clusters

Optimizing the electronic structure of the surface active sites and introducing functional sites for a photocatalyst are effective strategies to achieve the photocatalytic selective hydrogenation of biomass. Herein, Pt clusters/bimetallic NiMg-MOF-74 (MNM) ultrathin nanosheets were constructed for the photocatalytic precise hydrogenation of furfural (FUR) to furfuryl alcohol (FAL). A representative sample (Pt/MNM-0.25) shows 99.9% conversion of FUR and 99.9% selectivity of FAL. The electron density of surface coordinatively unsaturated NiII atoms in MNM is decreased after the doping of Mg. In situ ATR-IR indicated that the optimized surface NiII sites induced a more effective coordination activation of FUR molecules via the Ni-η1-(O)-furfural coordination. Electrochemical measurements and in situ EPR results reveal that Pt clusters are the functional surface sites for transferring the photogenerated electrons and dissociating H2. The synergistic effect of surface optimized NiII sites and Pt clusters is emphasized. This work successfully achieves the high-efficiency precise hydrogenation of FUR to FAL via designing surface functionalized Pt clusters/bimetallic MOF ultrathin nanosheets.

Crystal structure and Hirshfeld surface analysis of dichloridotetrakis(4-methyl-1H-pyrazole-κN 2)nickel(II) acetonitrile disolvate

The title compound, [NiCl2(C4H6N2)4]·2CH3CN, is a mononuclear octahedral NiII pyrazole-based complex. Two acetonitrile molecules are linked to the NiII complex by N—H...N hydrogen bonds. The NiII atom is octahedrally coordinated by four N atoms of four 4-methyl-1H-pyrazole ligands, forming the equatorial plane. The axial positions are occupied by two Cl atoms. [NiCl2(C4H6N2)4]·2CH3CN was synthesized by the reaction of 4-methyl-1H-pyrazole with nickel(II) chloride hexahydrate in acetonitrile solution under ambient conditions and characterized by single-crystal X-ray diffraction analysis. A Hirshfeld surface analysis was performed, which suggests that the most important contributions to the surface contacts are from H...H (62.1%), H...N/N...H (13.7%), H...C/C...H (13.4%) and H...Cl/Cl...H (10.1%) interactions.

Crystal structure of bis-{4-[(4-methyl-benz-yl)-oxy]-N'-(4-methyl-benzyl-idene)benzohydrazidato}nickel(II).

In the title complex, [Ni(C23H21N2O2)2], the central NiII atom is located on an inversion centre and exhibits a slightly distorted square-planar N2O2 coordination environment. A trans-configuration of the N,O chelating ligands results from the imposed site symmetry of the central NiII atom. In the crystal, individual mol-ecules stack along the a axis through weak π-π stacking inter-actions between the phenyl rings.

Crystal structure and Hirshfeld surface analysis of poly[[bis-[μ4-N,N'-(1,3,5-oxadiazinane-3,5-di-yl)bis(carbamoyl-methano-ato)]nickel(II)tetra-potassium] 4.8-hydrate

The title compound, {[K4Ni2(C7H6N4O7)2]·4.8H2O} n , was obtained as a result of a template reaction between oxalohydrazide-hydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed inter-mediate. The two independent [Ni(C7H6N4O7)]2- complex anions exhibit pseudo-C S symmetry and consist of an almost planar metal-containing fragment and a 1,3,5-oxadiazinane ring with a chair conformation disposed nearly perpendicularly with respect to the former. The central NiII atom has a square-planar N2O2 coordination arrangement formed by two amide N and two carboxyl-ate O atoms. In the crystal, the nickel(II) complex anions form layers parallel to the ab plane. Neighboring complex anion layers are connected by layers of potassium cations for which two of the four independent cations are disordered over two sites [ratios of 0.54 (3):0.46 (3) and 0.9643 (15):0.0357 (15)]. The framework is stabilized by an extensive system of hydrogen bonds where the water mol-ecules act as donors and the carb-oxy-lic O atoms, the amide O atoms and the oxadiazinane N atoms act as acceptors.

Influence of structural variation of salamo‐based ligand on supramolecular architectures, Hirshfeld analyses, and fluorescence properties of new tetranuclear NiII complexes

Two new tetranuclear NiII complexes, [Ni4(L1)2(N3)4(MeOH)2]·CH3COCH3 (1) and [Ni4(L2)2(N3)4(MeOH)2]·4CH3COCH3 (2), were synthesized using NiCl2·6H2O, NaN3, and asymmetric salamo‐based ligands H2L1 and H2L2, respectively. The structural characterization was made by elemental analyses, infrared (IR) and ultraviolet‐visible (UV‐vis) spectra, and X‐ray diffraction analyses. The results of X‐ray diffraction analyses show that the NiII atoms in complexes 1 and 2 are distorted octahedral geometries. Interestingly, the degree of distortion of the ligands in complexes 1 and 2 is different, which indicates that the interaction of NiII ions on different ligands is different. Meanwhile, the investigation of molecular packing by employing the Hirshfeld surface analysis exhibits that the percentages of C–H/H–C, O–H/H–O, and H–H/H–H contacts of the complex 1 (or 2) are calculated to be 17.7%, 7.9%, and 53.7% (or 18.8%, 13.8%, and 52.5%), respectively, where the H–H/H–H contacts have the characteristics of strong contacts whereas the O–H/H–O hydrogen bonds are considerably weak, and the studies on fluorescence properties further confirm the NiII atoms have different binding abilities to the different ligands.

Trans-Di-aqua-bis-(N,N,N'-tri-methyl-ethylenedi-amine)-nickel(II) dichloride.

In the title salt, [Ni(C5H12N2)2(H2O)2]Cl2, the asymmetric unit is comprised of half of the complex cation and a chloride ion with the NiII atom of the cation situated about a twofold rotation axis. The six-coordinate NiII atom of the cation is connected to four N atoms from two methyl-substituted ethyelenedi-amine ligands and two water mol-ecules in a slightly distorted octa-hedral environment. The five-membered chelate ring is in a slight envelope conformation. The crystal packing features O-H⋯Cl and N-H⋯Cl inter-molecular inter-actions with the Cl- ion forming weak bifurcated hydrogen bonds with nearby water mol-ecules and N-H inter-actions, leading to a three-dimensional supra-molecular network structure.

Hexa-aqua-nickel(II) bis-[tri-aqua-μ3-oxalato-di-μ-oxalato-bariumchromate(III)] tetra-hydrate.

The title compound, [Ni(H2O)6][BaCr(C2O4)3(H2O)3]2·4H2O, was obtained in the form of single crystals from the slow evaporation of an aqueous mixture of {Ba6(H2O)17[Cr(C2O4)3]4}·7H2O and NiSO4·6H2O in the molar ratio 1:4. Its structure is made up of corrugated anionic (101) layers of formula [BaCr(C2O4)3(H2O)3] n n - that leave voids accommodating the charge-compensating cations, [Ni(H2O)6]2+ (point group symmetry ), as well as the water mol-ecules of crystallization. The anionic layers are built from the connection of barium and chromium atoms through bridging oxalate ligands. The CrIII atom is hexa-coordinated by O atoms of three oxalate ligands while the BaII atom is tenfold coordinated by three O atoms of water mol-ecules and seven O atoms of four oxalate ligands. Each NiII atom sits on an inversion center and is coordinated by six water mol-ecules. One of the uncoordinated water mol-ecules is disordered over two sites, with a refined occupancy ratio of 0.51 (5):0.49 (5). In the crystal, extensive O-H⋯O hydrogen-bonding inter-actions link the anionic layers, the charge-balancing cations as well as the water mol-ecules of crystallization into a three-dimensional supra-molecular network.

Mono‐Phosphazenyl Phosphines (R2N)3P=N–P(NR2)2 – Strong P‐Bases, P‐Donors, and P‐Nucleophiles for the Construction of Chelates

We present a convenient three‐step synthesis of amino substituted phosphazenyl phosphines of the general formula (R2N)3P=N–P(NR2)2 [NR2 = N(CH2)4, N(CH2)5, N(CH2)6]. These easily accessible mixed valent compounds display a surprisingly high proton affinity and basicity in the same range as the corresponding Schwesinger diphosphazene (Me2N)3P=N–P=NEt(NMe2)2 (Et‐P2) and Verkade's proazaphosphatrane superbases. Within the central [PIII–N=PV] scaffold, the phosphine PIII and not the phosphazene NIII atom is the center of highest proton affinity, basicity and donor strength. As P‐bases, the title compounds display calculated proton affinities between 265.8 (NR2 = NMe2) and 274.7 kcal·mol–1 [NR2 = N(CH2)4] and pKBH+ values between 26.4 (NR2 = NMe2) and 31.5 [NR2 = N(CH2)4] on the acetonitrile scale. As P‐nucleophiles, they are key intermediates in the synthesis of hyperbasic bis(diphosphazene) proton sponges, chiral bis(diphosphazene) proton pincers, bisphosphazides, and superbasic P2‐bisylides. Their Staudinger reactions as nucleophile towards 1,8‐diazidonaphthalene leading to 1,8‐naphthalene‐bisphosphazides is described in detail. The donor strength of the title compounds towards fragments [Se] and [Ni(CO)3] is in the same range as that of N‐heterocyclic carbenes.

1,2-Bis(diiso-propyl-phosphan-yl)ethane-κ2 P,P'](2-fluoro-N-{[(2-fluoro-phen-yl)aza-nid-yl]carbon-yl}anilinido-κ2 N,N')nickel(II).

The mol-ecular structure of the title complex, [Ni(C13H8F2N2O)(C14H32P2)] or Ni(oFPU)(dippe), where oFPU is the dianion of bis-(2-fluoro-phen-yl)urea and dippe is 1,2-bis-(di-iso-propyl-phosphino)ethane, comprises an NiII atom with a distorted square-planar coordination environment (geometry index τ4 = 0.195). One of the fluoro-phenyl rings of the oFPU ligand is disordered over two sets of sites in an 0.832 (7):0.168 (7) ratio. The crystal structure displays C-H⋯O and C-H⋯F hydrogen-bonding inter-actions, leading to chains with R 2 2(12) motifs extending parallel to [100]. The title compound might be of inter-est with respect to the production of urea and carbamate derivatives of nickel(II).

Ni3Te2O2(PO4)2(OH)4, an open-framework structure isotypic with Co3Te2O2(PO4)2(OH)4.

Single crystals of Ni3(TeO(OH)2)2(PO4)2, trinickel(II) bis[(oxidodihydoxidotellurate(IV)] bis(phosphate),were obtained by hydro-thermal synthesis at 483 K, starting from NiCO3·2Ni(OH)2, TeO2 and H3PO4 in a molar ratio of 1:2:2. The crystal structure of Ni3Te2O2(PO4)2(OH)4 is isotypic with that of Co3Te2O2(PO4)2(OH)4 [Zimmermann et al. (2011 ▸). J. Solid State Chem. 184, 3080-3084]. The asymmetric unit comprises two Ni (site symmetries , 2/m) one Te (m), one P (m), five O (three m, two 1) and one H (1) sites. The tellurium(IV) atom shows a coordination number of five, with the corresponding [TeO3(OH)2] polyhedron having a distorted square-pyramidal shape. The two NiII atoms are both octa-hedrally coordinated but form different structural elements: one constitutes chains made up from edge-sharing [NiO6] octa-hedra extending parallel to [010], and the other isolated [NiO2(OH)4] octa-hedra. The two kinds of nickel/oxygen octa-hedra are connected by the [TeO3(OH)2] pyramids and the [PO4] tetra-hedra through edge- and corner-sharing into a three-dimensional framework structure with channels extending parallel to [010]. Hydrogen bonds of medium strength between the hy-droxy groups and one of the phosphate O atoms consolidate the packing. A qu-anti-tative structure comparison between Ni3Te2O2(PO4)2(OH)4 and Co3Te2O2(PO4)2(OH)4 is made.

Tetra-aqua-[3-oxo-1,3-bis-(pyridinium-2-yl)propan-1-olato]nickel(II) tribromide dihydrate.

The crystal structure of the title compound, [Ni(C13H11N2O2)(H2O)4]Br3·2H2O, contains an octa-hedral NiII atom coordinated to the enol form of 1,3-di-pyridyl-propane-1,3-dione (dppo) and four water mol-ecules. Both pyridyl rings on the ligand are protonated, forming pyridinium rings and creating an overall ligand charge of +1. The protonated nitro-gen-containing rings are involved in hydrogen-bonding inter-actions with neighoring bromide anions. There are many additional hydrogen-bonding inter-actions involving coordinated water mol-ecules on the NiII atom, bromide anions and hydration water mol-ecules.

Supramolecular Architecture in a Ni(II) Complex with a Weakly Bonded N,N′-(1,4-phenylenedi- carbonyl)Diglycinate Counter-Anion: Crystal Structure Investigation and Hirshfeld Surface Analysis

In this work, we describe the structural investigation of a Ni(II) complex, [Ni(C12H8N2)2(H2O)2]2·(C12H10N2O6)·(NO3)2·10H2O, with phenanthroline ligands, a deprotonated aromatic dicarboxylic acid, N,N′-(1,4-phenylenedicarbonyl)diglycine, and a nitrate as counter-anions, as well as water molecules. Noncovalent interactions, such as π–π stacking, lone-pair···π, and C–H···π between the phenanthrolines of the cationic complex, [Ni(C12H8N2)2(H2O)2]2+, and counter-anions are observed. Moreover, the solvated and noncoordinating counter-anion, N,N′-(1,4-phenylenedicarbonyl)diglycinate, is embedded in classical and nonclassical hydrogen-bonding interactions with water molecules and phenanthrolines. The two water molecules coordinated by the NiII atom and hydrogen bonded to the carboxylate of the N,N′-(1,4-phenylenedicarbonyl)diglycinate show attractive secondary electrostatic interactions, and a DD/AA hydrogen bonding pattern is formed. The noncovalent interactions of the cationic complex and the solvated N,N′-(1,4-phenylenedicarbonyl)diglycinate counter anion were explored with a Hirshfeld surface analysis, and related contributions to crystal cohesion were determined. The results of the N,N′-(1,4-phenylenedicarbonyl)diglycinate counter anion were compared to those of a solvated N,N′-(1,4-phenylenedicarbonyl)diglycine molecule of a previously described copper(II) complex.