Complexes of Platinum(II) Chloride with Cyanophosphines

Platinum(II) cyanophosphine complexes PtL₂Cl₂, where L = P(CN)₃, PhP(CN)₂, or Ph₂PCN, were synthesized. Their properties and mode of coordination were examined.     

Complexes of Nickel(II) Thiocyanate with Anilines

Complexes of the type NiL₂(SCN)₂ (L = aniline, o-, m-, p-toluidine, o-, m-, p-anisidine and p-phenetidine) have been prepared and characterised by room temperature magnetic moments and infra-red spectral data (down to 250 cm^?1) in the solid state. The thiocyanate is present as a bridging group and the metal atom is shown to be in a six-coordinate environment having an octahedral stereochemistry.     

Nickel(II) and Zinc(II) Complexes with Benzoylacetaldehyde Derivatives

Russian Journal of Coordination Chemistry - Ni(II) and Zn(II) complexes, [M(Ln)A] (n = 1–3, A = NH3, Py), were prepared from the products of condensation of benzoylacetaldehyde with aromatic...     

Copper(II) and Nickel(II) Complexes of `trans'-Difunctionalized Tetraaza Macrocycles

Reductive cleavage of the bis-aminal 1 of 1,4,8,11-tetraazacyclotetradecane allows a new synthesis of 1,8-dimethyl-1,4,8,11-tetraazacyclotetradecane ( 3 ), which is an ideal starting compound for preparing `trans'-difunctionalized derivatives. Thus, 3 was reacted to give the macrocyclic diacetonitrile 5 and dipropanenitrile 9 . These were reduced with Raney-Ni and H₂ to the corresponding diamines 6 and 10 , respectively. In addition, 5 was selectively hydrolysed to the diacetamide 7 and fully hydrolysed to the diacetic acid 8 . The Cu²⁺ and Ni²⁺ complexes of these new ligands were prepared and their spectral and structural properties studied. Whereas 3 yielded square planar species, the functionalized derivatives gave penta- or hexacoordinate complexes. The ligands with amino groups in their side chains ( 6 and 10 ) formed square planar species at acidic pH (amino groups protonated), but pentacoordinate geometries resulted at alkaline pH, where one amino group underwent coordination. In contrast, the diacetic acid 8 gave distorted octahedral Cu²⁺ and Ni²⁺ complexes.     

Ethylene Oligomerization Catalyzed by Nickel(II) Diimine Complexes

ＩｎｔｒｏｄｕｃｔｉｏｎＬｏｗ ｃａｒｂｏｎｌｉｎｅａｒα ｏｌｅｆｉｎｓａｒｅｕｓｅｄｐｒｉｍａｒｉｌｙａｓｃｏ ｍｏｎｏｍｅｒｓｆｏｒｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆｌｉｎｅａｒｌｏｗｄｅｎｓｉｔｙｐｏｌｙｅｔｈｙｌｅｎｅ (ＬＬＤＰＥ) ,ｐｌａｓｔｉｃｉｚｅｒｓａｎｄｓｙｎｔｈｅｔｉｃｌｕｂｒｉ ｃａｎｔｓ .Ｉｎｒｅｃｅｎｔｙｅａｒｓ ,ｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎａｔｔｒａｃｔｅｄｔｏｔｈｅｆｉｅｌｄｏｆｃａｔａｌｙｔｉｃｂｅｈａｖｉｏｒｏｆｌａｔｅｔｒａｎｓｉｔｉｏｎｍｅｔａｌｃｏｍ…     

Ethylene Oligomerization Catalyzed by Nickel（Ⅱ） Diimine Complexes

Ethylene oligomerization has been investigated by using catalyst systems composed of nickel(II) diimine complexes (diimine = N, N′‐o‐phenylene bis (salicylideneaminato), N, N′‐o‐phenylenebisbenzal, N, N′‐ethylenebisbenzal) and ethylaluminoxane (EAO). The main products in toluene and at 110–200 °C were olefins with low carbon numbers (C₄—C₁₀). Effects of reaction temperature, Al/Ni molar ratio and reaction period on both the catalytic activity and product distribution were explored. The activity of 1.84 × 10⁵ g of oligomer/(mol_NI · h), with 87.4% of selectivity to C₄—C₁₀ olefins, was attained at 200 °C in the reaction when a catalyst composed of NiCl₂ (PhCH = o‐NC₆H₄N = CHPh) and EAO was used.     

N-Formamid osalicylaldimine andN-Acetamidosalicylaldimine Complexes of Copper(II), Nickel(II) and Cobalt(II)

Summary N-formamidosalicylaldimine (H₂SF) andN-acetamidosalicylaldimine (H₂SA) complexes of Cu^II, Ni^II and Co^II have been synthesized and characterized by analytical, spectroscopic and magnetic data. The ligands coordinate to the metalvia the hydroxyl, carbonyl and imino groups to yield normal paramagnetic and insoluble complexes which decompose above 250°.     

Cobalt(II), Nickel(II), and Copper(II) Complexes with Diphenylthiocarbazide

New [ML(H₂O)₂] complexes (M = Co²⁺, Ni²⁺, or Cu²⁺; H₂L = diphenylthiocarbazide) were synthesized and studied using IR and diffuse reflection electronic spectroscopy, magnetic chemistry, conductometry, and DTA. The metals were shown to coordinate L^2–through nitrogen and sulfur atoms. The complex [CuL(H₂O)₂] is a dimer.     

Synthesis and Characterization of Two Trinuclear Nickel(II) Complexes

Two novel trinuclear nickel(II) complexes have been synthesized and characterized by X‐ray single crystal diffraction. Compound [Ni₃(ashz)₃(py)₂(DMF)₂]·(DMF)₂ ( 1 ) crystallizes in the monoclinic, space group C2/c, with a = 22.114(2), b = 10.509(9), c = 19.485(2) Å, β = 114.443(1)°, Z = 4; compound [Ni₃(acshz)₃(py)₂(DMF)₂]·(DMF)₂ ( 2 ) crystallizes in the monoclinic space group P2₁/n with a = 20.0620(2), b = 9.7017(6), c = 25.0533(2) Å, β = 97.0610(2)°, Z = 4, where ashz and acshz are deprotonated N‐acetylsalicylhydrazide (H₃ashz) and N‐acetyl‐5‐chlorosalicylhydrazide (H₃acshz), respectively. The crystal structure analysis of 1 and 2 showed that three Ni²⁺ ions in a linear arrangement are bridged by two ligands ((ashz)^3? or (acshz)^3?) to form a neutral nuclear with two four‐coordinate square‐planar nickel ions linked by a six‐coordinate octahedral central nickel ion.     

Nickel(II) Analogues of Phosphorescent Platinum(II) Complexes with Picosecond Excited-State Decay

Square-planar Ni^II complexes are interesting as cheaper and more sustainable alternatives to Pt^II luminophores widely used in lighting and photocatalysis. We investigated the excited-state behavior of two Ni^II complexes, which are isostructural with two luminescent Pt^II complexes. The initially excited singlet metal-to-ligand charge transfer (¹MLCT) excited states in the Ni^II complexes decay to metal-centered (³MC) excited states within less than 1 picosecond, followed by non-radiative relaxation of the ³MC states to the electronic ground state within 9–21 ps. This contrasts with the population of an emissive triplet ligand-centered (³LC) excited state upon excitation of the Pt^II analogues. Structural distortions of the Ni^II complexes are responsible for this discrepant behavior and lead to dark ³MC states far lower in energy than the luminescent ³LC states of Pt^II compounds. Our findings suggest that if these structural distortions could be restricted by more rigid coordination environments and stronger ligand fields, the excited-state relaxation in four-coordinate Ni^II complexes could be decelerated such that luminescent ³LC or ³MLCT excited states become accessible. These insights are relevant to make Ni^II fit for photophysical and photochemical applications that relied on Pt^II until now.     

Water-Soluble Polymeric Complexes of Cobalt(II) and Nickel(II) with Azolate Anions

N-Unsubstituted azoles (1,2,4-triazole, 3-amino-1,2,4-triazole) and 5-R-tetrazoles (R = H, CH₃, C₂H₅, C₄H₉, CH = CH₂, C₆H₅, p-CH₃C₆H₄, NH₂) form water-soluble polymeric complexes in systems containing certain transition metal salts. The data obtained and the results of MP2/6-31G^{* *} calculations of the electronic structures of 5-R-tetrazolate anions show that the ability of azoles for formation of polymeric complexes with transition metal ions is mostly determined by the acid-base properties of azoles. The geometric structure of a polymeric chain with the Co²⁺ ion having the coordination number 6 and the 5-methyltetrazolate anion being a bridging ligand was examined at the STO-3G level. It was shown that the coordination by the 2- and 3-nitrogen atoms of the tetrazole ring is most favored by energy.     

Copper(II), Nickel(II) and Cobalt(II) Complexes of Dibasic Tridentate Schiff Bases

Complexes of Cu(II), Ni(II) and Co(II) with the Schiff bases derived from o-aminobenzoic acid with salicylaldehyde and its 5-chloro and 5-bromo derivatives have been prepared. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility and electronic spectra of Cu(II) complexes indicate the nonplanar binuclear structures while that of Ni(II) and Co(II) show their paramagnetic octahedral geometry. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type (Cu·L)₂, Ni·L·3H₂O and Co·L·3H₂O are formed having solvent molecule in coordination with the metal ion. The monopyridine and monoammonia adducts of Cu(II) complexes were found to be monomeric.     

Complexes of Cobalt(II), Nickel(II) and Copper(II) Chloroacetates with Quinoline N-Oxide

Some 1:1 and 1:2 adducts of cobalt(II), nickel(II) and copper(II) chloroacetates with quinoline N -oxide have been isolated by the interaction of the appropriate metal chloroacetate with quinoline N -oxide (QuinNo). The complexes isolated are of 1:1 stoichiometry of formula [M(CH₃_xClxCOO)₂QuinNO] (when M=Co(II), Ni(II); X=1,2 and 3 and when M=Cu(II), X=l and 2) except copper(II) trichloroacetate which yields an adduct of 1:2 stoichiometry of formula[Cu(CCI₃COO)₂(QuinNO)₂]. The adducts isolated are soluble in common organic solvents.     

Zinc(II), Cobalt(II) and Nickel(II) Complexes of 5-Substituted-1,3,4-Thiadiazoles

Zn(II), Co(II) and Ni(II) complexes with some 5-substituted-1,3,4-thiadiazoles (L₁-L₄) have been prepared and characterized by conductivity, microanalysis, thermal analysis, infrared and electronic spectra measurements. All complexes behave as 1:1 electrolyte and the ligands are coordinated as bidentate molecules. The stability constants and energy of formation are determined and discussed on the basis of the ligands structure.     

Complexes of Cobalt(II), Nickel(II) and Copper(II) Chloroacetates with Quinoline N-Oxide

Some 1:1 and 1:2 adducts of cobalt(II), nickel(II) and copper(II) chloroacetates with quinoline N -oxide have been isolated by the interaction of the appropriate metal chloroacetate with quinoline N -oxide (QuinNo). The complexes isolated are of 1:1 stoichiometry of formula (M(CH_3-xCl_xCOO)₂QuinNO) (when M=Co(II), Ni(Il); X=l, 2 and 3 and when M=Cu(II), X=1 and 2) except copper(II) trichloroacetate which yields an adduct of 1:2 stoichiometry of formula[Cu(CCl₃COO)₂ (QuinNO)₃]. The adducts isolated are soluble in common organic solvents.     

Polarographic Determination of Famotidine through Complexation with Nickel(II) Chloride

The present investigation describes the development of a sensitive, rapid polarographic method for the determination of famotidine in pure form and in certain dosage forms. The proposed method depends upon studying the polarographic activity of Nickel(II)‐famotidine complex in Britton Robinson buffer over the pH range 4–8 and its usefulness in the analysis of famotidine using direct current (DC_t), differential pulse (DPP), and alternating current (AC_t) polarography. The different experimental parameters affecting the cathodic waves were carefully investigated and optimized. Moreover, to check the validity of the proposed method, the standard addition method was applied by adding famotidine to the previously analyzed tablets. The recovery of the drug was calculated by comparing the concentration obtained from the spiked mixtures with those of the pure drug. The results of analysis of commercial tablets and the recovery study suggested that there is no interference from any excipients, which are present in tablets. Statistical comparison of the results was performed with regard to accuracy and precision using student's t‐test and F‐ratio at 95% confidence level. There is no significant difference between the comparison and proposed method with regard to accuracy and precision.