Bis‐NHC Chelate Complexes of Nickel(0) and Platinum(0)

For a long time d¹⁰‐ML₂ fragments have been known for their potential to activate unreactive bonds by oxidative addition. In the development of more active species, two approaches have proven successful: the use of strong σ‐donating ligands leading to electron‐rich metal centers and the employment of chelating ligands resulting in a bent coordination geometry. Combining these two strategies, we synthesized bis‐NHC chelate complexes of nickel(0) and platinum(0). Bis(1,5‐cyclooctadiene)nickel(0) and ‐platinum(0) react with bisimidazolium salts, deprotonated in situ at room temperature, to yield tetrahedral or trigonal‐planar bis‐NHC chelate olefin complexes. The synthesis and characterization of these complexes as well as a first example of C? C bond activation with these systems are reported. Due to the enforced cis arrangement of two NHCs, these compounds should open interesting perspectives for bond‐activation chemistry and catalysis.     

Triangular Nickel Complexes Derived from 2‐Pyridylcyanoxime: An Approach to the Magnetic Properties of the [Ni3(μ3‐OH){pyC(R)NO}3]2+ Core

A series of nickel complexes with nuclearity ranging from Ni₃ to Ni₆ have been obtained by treatment of a variety of nickel salts with the 2‐pyridylcyanoxime ligand. The reported compounds have as a common structural feature the triangular arrangement of nickel cations bridged by a central μ₃‐oxo/alkoxo ligand. These compounds are simultaneously the first nickel derivatives of the 2‐pyridylcyanoxime ligand and the first examples of isolated, μ₃‐O triangular pyridyloximate nickel complexes. Magnetic measurements reveal antiferromagnetic interactions promoted by the μ₃‐O and oximato superexchange pathways and comparison of the experimental structural and magnetic data with DFT calculations give an in‐depth explanation of the factors that determine the magnetic interaction in this kind of system.     

Spectroscopic evidence for a dinitrogen complex of gallium and estimation of the Ga-N2 bond strength

Matrix-isolation experiments were performed to study the interaction between Ga atoms and N2 by using Raman and UV/Vis spectroscopies for detection and analysis. It was revealed that a weak complex is formed, for which resonance Raman spectra were obtained. Several overtones were sighted, allowing a rough estimate of the Ga-N2 fragmentation energy to be made (approximately 19 kJ mol(-1)). The excitation profile obtained from the spectra at different laser wavelengths agrees with the UV/Vis spectrum and shows that the complex exhibits an electronic transition at around 410 nm. At the Ga atom, this transition can be described as a 2S<--2P or 2D<--2P excitation, which is red-shifted from its position for free Ga atoms (approximately 340 nm and 270 nm for 2S<--2P and 2D<--2P, respectively) as a result of N2 complexation. The effect of complexation involves, therefore, only slight stabilization of the 2P ground state but relatively strong stabilization of the excited (2)S state. Accordingly, for the Ga atom in its excited 2S state, the Ga-N2 bond energy can be estimated to be around 79 kJ mol(-1).     

Counter‐Intuitive Gas‐Phase Reactivities of [V2]+ and [V2O]+ towards CO2 Reduction: Insight from Electronic Structure Calculations

[V₂O]⁺ remains “invisible” in the thermal gas‐phase reaction of bare [V₂]⁺ with CO₂ giving rise to [V₂O₂]⁺; this is because the [V₂O]⁺ intermediate is being consumed more than 230 times faster than it is generated. However, the fleeting existence of [V₂O]⁺ and its involvement in the [V₂]⁺ → [V₂O₂]⁺ chemistry are demonstrated by a cross‐over labeling experiment with a 1:1 mixture of C¹⁶O₂/C¹⁸O₂, generating the product ions [V₂¹⁶O₂]⁺, [V₂¹⁶O¹⁸O]⁺, and [V₂¹⁸O₂]⁺ in a 1:2:1 ratio. Density functional theory (DFT) calculations help to understand the remarkable and unexpected reactivity differences of [V₂]⁺ versus [V₂O]⁺ towards CO₂.     

Vibrational Spectrum and Gas‐Phase Structure of Disulfur Dinitride (S2N2)

Gas‐phase FTIR spectra of the ν₆ (B‐type) and the ν₄ (C‐type) fundamental bands of S₂N₂ (D_2h) were recorded with a resolution of ≤0.004 cm^?1 and the vibrational spectrum of S₂N₂ (D_2h) in solid Ar has been revisited. All IR‐active fundamentals and four combination bands were assigned in excellent agreement with calculated values from anharmonic VPT2 and VCI theory based on (explicitly correlated) coupled‐cluster surfaces. Accurate experimental vibrational ground‐ and excited‐state rotational constants of ³²S₂¹⁴N₂ are obtained from a rovibrational analysis of the ν₆ and ν₄ fundamental bands, and precise zero‐point average r_z (R_z(SN)=1.647694(95) Å, α_z(NSN)=91.1125(33)°) and semi‐experimental equilibrium structures (R_e(SN)=1.64182(33) Å, α_e(NSN)=91.0716(93)°) of S₂N₂ have been established. These are compared to the solid‐state structure of S₂N₂ and structural properties of related sulfur nitrogen compounds and to results of ab initio structure calculations.     

Structure and bonding of lanthanide dinitrogen complexes,Ln(N2)1-8

Lanthanide dinitrogen complexes, Ln(N₂) _x (x = 1-8), were investigated by Density Functional Theory computations using the B3LYP exchange-correlation functional in conjunction with quasirelativistic pseudopotentials for Ln. After a recent study on the lanthanum complexes (A. Kovács, Structural Chemistry 2018 , 29, 1825), the present study aimed to probe the changes upon variously filled 4f subshells of Ln on the structures, stabilities, and bonding properties in related complexes of Nd, Ho, and Lu. The bonding properties were assessed on the basis of natural atomic charges, Ln valence orbital populations, and analysis of bonding molecular orbitals.     

Formation and Characterization of the Boron Dicarbonyl Complex [B(CO)2]−

We report the synthesis and spectroscopic characterization of the boron dicarbonyl complex [B(CO)₂]^?. The bonding situation is analyzed and compared with the aluminum homologue [Al(CO)₂]^? using state‐of‐the‐art quantum chemical methods.     

The Electronic Structure and Photochemistry of Group 6 Bimetallic (Fischer) Carbene Complexes: Beyond the Photocarbonylation Reaction

The UV spectra of Group 6 metal carbene complexes bearing a CpM(CO)₃ (Cp=cyclopentadienyl) moiety bonded to the carbene carbon atom exhibit a redshift of the absorption maxima at higher wavelengths with respect to the parent monometallic complexes. This redshift is partly due to a higher occupation on the p_z atomic orbital of the carbene carbon atom. Time‐dependent DFT calculations accurately assign this band to a metal‐to‐ligand charge‐transfer transition, thus showing that the presence of a second metal center does not affect the nature of the transition. However, the photochemical reactivity of Group 6 metal carbene complexes bearing a CpM(CO)₃ moiety strongly depends on the nature of this metal fragment. A new photoslippage reaction leading to fulvenes occurs when Mn‐derived products 11 a , 11 b , and 12 a are irradiated (both Cr and W derivatives), whereas Re‐derived product 11 c behaves like standard Fischer complexes and yields the usual photocarbonylation products. A new photoreduction process occurring in the metallacyclopropanone intermediate is also observed for these complexes. Both computational and deuteration experiments support this unprecedented photoslippage process. The key to this differential photoreactivity seems to be the M–Cp back‐donation, which hampers the slippage process for Re derivatives and favors the carbonylation reaction.     

混合配体镍配合物[Ni（NCS）2（phen）2]的合成、晶体结构及荧光性质

合成了含异硫氰酸根和邻菲咯啉（phen）混合配体的镍配合物[Ni（NCS）2（phen）2],通过红外光谱、紫外光谱和X射线单晶衍射等手段对其结构进行了表征.研究了配合物的固体荧光光谱.单晶结构解析结果表明,标题化合物属于正交晶系,Pbcn空间群,晶胞参数为：a=1.296 2（2）nm,b=1.019 0（1）nm,c=1.759 5（2）nm,V=2.323 9（4）nm3,Z=4,Dc=1.530 g/cm3,μ=1.043 mm-1,F（000）=1 096,R1=0.042 1,wR2=0.108 1.配合物中镍离子采用6配位的八面体配位构型,晶体堆积中通过π-π作用形成一维超分子结构.     

Characterization and Crystal Structure of Bis(N''-ethyl-N-piperazinly-carbodithioato-S ,S '') Nickel(Ⅱ) Complex: Ni(S2CNC4H8NC2H5)2

The title compound has been prepared and characterized by elemental analysis,infrared and FT-Raman spectra, and thermal analysis. The crystal and molecular structures of bis(N'-ethyl-N-piperazinly-carbodithioato-S,S') nickel(Ⅱ) complex (Ni(S2CNC4H8NC2H5)2) were determined by X-ray diffraction methods. The crystal crystallizes in the triclinic system, space group P1 with a = 0.66770(15), b = 0.85066(12), c = 0.8973(2) nm, α = 84.97(2), β =78.71 (2), γ =80.12(2)°, Mr = 437.34, V = 0.49160(17) nm3, Z = 1, Dc = 1.477 g/cm3, F(000) = 230, R = 0.0422and wR = 0.1290. In the structure, the central Ni atom is coordinated in a slightly distorted square plane by four S atoms from two bidentate S2CNC4H8NC2H5 ligands with the four Ni-S bond distances in the range of 0.22065(10)～0.22076(9) nm. The IR and FT-Raman spectral data are in agreement with the structural data. Thermal analysis indicates that the title compound decomposes completely at the temperature of 799.88 ℃, leaving NiS.     

Characterization and Crystal Structure of Bis(N'-ethyl-N-piperazinly-carbodithioato-S,S') Nickel(II) Complex:Ni(S_2CNC_4H_8NC_2H_5)_2

1 INTRODUCTION The ability of dialkyldithiocarbamate anion, -S2- CNR2 (dtc) ligand, to bind metal has been known for many years[1, 2]. It forms a chelate with virtually all transition elements and is proven to be a versatile chelating agent for the separation and extract of metals in analytical chemistry and mineral floa- ting[3～5]. Water soluble dialkyldithiocarbamate com- plexes have been tested in various medical appli- cations[6]. Some of substituted dithiocarbamate salts also show …     

Synthesis,Characterization and Structure of Bis‐ and Tetrakis‐Aziridine‐Nickel(II) and Copper(II) Complexes

The synthesis and characterization of mononuclear tetrakis‐aziridine nickel(II ) and copper(II ) complexes as well as of a dinuclear bis‐aziridine copper(II ) complex are described. The reactions of anhydrous MCl₂ (M = Ni^II, Cu^II) with aziridine (= az = C₂H₄NH, C₂H₃MeNH, CH₂CMe₂NH) in CH₂Cl₂ at room temperature in a 1:5 and 1:2 molar ratio, respectively, afforded the tetrakis‐aziridine complexes [M(az)₄Cl₂] (M = Ni, Cu) or the dimeric bis‐aziridine complex [Cu(az)₂Cl₂]₂. After purification, all of the complexes were fully characterized. The single crystal structure analysis revealed two different coordination modes. Whereas both nickel(II ) complexes can be classified as showing an elongated octahedral structure, copper(II ) complexes show either an elongated octahedral or a square pyramidal arrangement forming dimers with chlorido bridges in axial positions. Furthermore, the results of magnetic measurements of the nickel(II ) and copper(II ) compounds are presented.     

两个N-己酰基水杨酰肼合镍(Ⅱ)配合物的合成、结构及抗菌活性的研究

The two trinuclear nickel（Ⅱ） complexes, Ni3（C13H15N2O3）2（C5H5N）4 （1） and Ni3（C13H15N2O3）2（C5H5N）2- （C3H7NO）2 （2）, were prepared by the reaction of Ni（OAc）2·4H2O with N-hexanoylsalicylhydrazide. The crystal structures of complexes were determined by X-ray diffraction analysis. Complex 1 takes triclinic symmetry with space group P-1 and cell dimensions of a=0.92377（2） nm, b= 1.08786（6） nm, c= 1.29391（3） nm, α=76.395（4）°, β=78.418（3）°, γ=67.378（4）°, V= 1.15772（7） nm^3, Z= 1,μ= 12.63 cm^-1. Complex 2 belongs to triclinic system and P2（1） space group and the crystallographic data： a= 1.4889（2） nm, b= 1.0389（1） nm, c= 1.4994（2） nm, β= 96.174（4）°, V=2.3058（5） nm^3, Z=2,μ= 12.70 cm^-1. The structures of the two molecules are similar. The three nickel atoms in each molecule of the two title complexes arrange in a strictly linear structure. The central nickel atom of the molecule adopts octahedral configuration, while the two nickel atoms on the two sides adopt square-planar configuration in each molecule. But the central nickel atoms of the two complexes have different axial ligands, which cause a slight difference in the bond distances of the octahedron. The antibacterial activity of compound 1 against seven common bacteria was investigated.     

Syntheses， Characterization and Magnetism of μ－2－Chloroterephthalato Nickel（Ⅱ） Binuclear Complexes

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Synthesis, Characterization and Crystal Structure of the First Tri-nuclear MFe2（M = Cu and Ni） Complexes Based on Nitroprusside

IntroductionSince 184 8,whenPlayfairpublishedthefirstpaperrelatedtonitroprussides ,1thetransitionmetalpenta cyanonitrosylmetallatehydrateshavebeenwidelystudiedbecauseoftheirimportantrolesinmolecularsieves ,cationexchangers,electronscavengersandradionuclidesor bents .2 4 Thenitroprussides ,regardlessofthecationicmetal,arecurrentlyemployedasreversibleinhibitorsofagroupofenzymesknownassuperoxidedismutases .5Recently ,using [Fe(CN ) 5(NO) ]2 - asabuildingblock ,somenitroprusside bridgedpolymeri…     

Crystal Structure and Spectroscopic Studies of Bis (morpholine dithiocarbamate) Nickel(II) Complex,Ni(C4H8ONCS2)2

The title compound has been prepared and characterized by EA, IR and TG spectral studies. The crystal structure of nickel (H) bis(morpholine dithiocarbamate) Ni(C₄H₅ONC‐S₂)₂ is determined by X‐ray diffraction methods. It crystallizes in the monoclinic system, space group P2₁/n, with lattice parameters a = 0.4288(1), b = 2.0526(4), c = 0.8333 (2) nm, β = 97.43(3)°, and Z = 2. In the structure, central Ni atom coordination geometry is slightly distorted square‐planar with the four S atoms from two morpholine dithiocarbamate ligands. The four Ni? S bond distances are in the range of 0.2199(5)–0.2201(2) nm. The ER spectral data are in agreement with the structural ones. The TG data indicate that it decomposed completely at the 766.89°C.     

Magnetic Properties and Electronic Structure of Neptunyl(VI) Complexes: Wavefunctions,Orbitals, and Crystal‐Field Models

The electronic structure and magnetic properties of neptunyl(VI), NpO₂²⁺, and two neptunyl complexes, [NpO₂(NO₃)₃]^? and [NpO₂Cl₄]^2?, were studied with a combination of theoretical methods: ab initio relativistic wavefunction methods and density functional theory (DFT), as well as crystal‐field (CF) models with parameters extracted from the ab initio calculations. Natural orbitals for electron density and spin magnetization from wavefunctions including spin–orbit coupling were employed to analyze the connection between the electronic structure and magnetic properties, and to link the results from CF models to the ab initio data. Free complex ions and systems embedded in a crystal environment were studied. Of prime interest were the electron paramagnetic resonance g‐factors and their relation to the complex geometry, ligand coordination, and nature of the nonbonding 5f orbitals. The g‐factors were calculated for the ground and excited states. For [NpO₂Cl₄]^2?, a strong influence of the environment of the complex on its magnetic behavior was demonstrated. Kohn–Sham DFT with standard functionals can produce reasonable g‐factors as long as the calculation converges to a solution resembling the electronic state of interest. However, this is not always straightforward.