Redox Kinetics as a Probe of the Supramolecular Interaction of α- and β-Cyclodextrins with Amphiphilic Nickel(II) Complexes of Pentaazamacrocycles Bearing Aliphatic Tails

Host–guest interactions between α- and β-cyclodextrins and nickel(II) polyazamacrocycles bearing aliphatic pendant arms (n-butyl, n-octyl and n-dodecyl) have been investigated, using redox kinetics as a probe, to estimate binding constants. Electrospray mass spectrometry shows the formation of inclusion complexes in aqueous solution. Cyclic voltammetric measurements show the cyclodextrins to have no effect on the redox potentials for the nickel(II/III) couples. Kinetics of oxidation of the nickel(II) complexes to the tervalent state exhibits rate retardation in the presence of the cyclodextrins. The outer-sphere oxidation of the nickel(II) macrocycles by aqua(5, 5, 7, 12, 12, 14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-1-acetato)nickel(III), [Ni(hmca)(OH₂)]²⁺ obeys the rate law: $${ \hbox{Rate} ={k}_{\rm obs}[\hbox{Ni}^{\rm III}\hbox{(hmca)}\hbox{(OH}_{\rm 2})]=\frac{{[k}_{\rm 2} + {k}_{\rm 3}{K}_{\rm CD}\hbox{][Ni}^{\rm II}\hbox{L][Ni}^{\rm III}\hbox{(hmca)(OH}_{\rm 2}{)]}}{{(1 + K}_{\rm {CD}}\hbox{[CD])}}}$$ where k ₂ is the rate constant for oxidation of the nickel(II) macrocycle in the absence of cyclodextrins, and k ₃ is that for oxidation of the {NiL.CD} inclusion complex.     

Oxydation von Nickel(0)-Komplexen mit cyclischen Carbonsäureamiden

Oxidation of Nickel(0) Complexes by Cyclic Imides of Dicarbonic Acids Normally, phthalimide (PI? H) or succinimide (SI? H) react with nickel(0) complexes — (dipy)Ni(COD) or (Ph₃P)₂Ni(C₂H₄) — by oxidative addition. The reaction of PI? H and the strong reductant (dipy)Ni(COD) is initiated by a one-electron transfer. Depending on the solvent, the resulting ion pair affords (dipy)Ni^I(PI) by spontaneous fragmentation or (dipy)Ni^II(H)(PI) by cage collaps. No interaction is found between the weak reductant (Ph₃P)Ni(C₂H₄) and PI? H. Phosphine-containing nickel(0) complexes are electrophilically attacked by the acid NH group of SI? H. Hydrido complexes of nickel(0), such as (Cy₃P)₂Ni(H)(SI), or secondary products of them, such as [(SI)Ni(THF)]₂NH, are formed. On the other hand, the reaction with (dipy)Ni(COD) affords only the binuclear substitution product [(dipy)Ni]₂(SI? H)(THF). In solution prolongated heating of (dipy)Ni(PI)(THF)_0,5 results in a partial decarbonylation. In contrast to the reaction of (dipy)Ni(COD) and cyclic carbonic acid anhydrides, no definite metalla rings but by an interaction with the solvent, benzamide is formed. With (dipy)Ni(COD) maleinimide does not react like on NH-acidic compound but like a polar olefine by substitution.     

Potentiometric Titrations and Nickel(II) Complexes of Four Topologically Constrained Tetraazamacrocycles

Abstract

The novel high spin Ni²⁺ complexes of the topologically constrained tetraazamacrocycles (1–4) [4,11-dimethyl-1,4,8,11 - tetraazabicyclo[6.6.2]hexadecane (1); 4,10-dimethyl-1,4,7,10-tetraazabicyclo[6.5.2]pentadecane (2); 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (3); racemic-4,5,7,7,11,12,14,14-octamethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (4)] show striking properties. Potentiometric titrations of the ligands 2 and 4 revealed them to be proton sponges, as reported earlier for 1 [1]. Ligand 3 is less basic, losing its last proton with a pK = 11.3(2). Despite high proton affinities, complexation reactions in the absence of protons successfully yielded Ni²⁺ complexes in all cases. The X-ray crystal structures of Ni(1)(acac)⁺, Ni(3)(acac)⁺ and Ni(1)(OH₂)₂ ²⁺ demonstrate that the ligands enforce a distorted octahedral geometry on Ni²⁺ with two cis sites occupied by other ligands. Magnetic measurements and electronic spectroscopy on the corresponding Ni(L)Cl₂ (L = 1–3) complexes reveal that all are high spin and six-coordinate with typical magnetic moments. In contrast, [Ni(4)Cl⁺] is five-coordinate with a slightly higher magnetic moment and its own characteristic electronic spectrum. The extra methyl groups on ligand 4 define a shallow cavity, sterically allowing only one chloride ligand to bind to the nickel(II) ion.     

Nickel Tetracarbonyl as Starting Material for the Synthesis of NHC-stabilized Nickel(II) Allyl Complexes

A novel, useful in situ synthesis for NHC nickel allyl halide complexes [Ni(NHC)(η³-allyl)(X)] starting from [Ni(CO)₄], NHC and allyl halides is presented. The reaction of [Ni(CO)₄] with (i) one equivalent of the corresponding NHC and (ii) with an excess of the corresponding allyl chloride at room temperature leads with elimination of carbon monoxide to complexes of the type [Ni(NHC)(η³-allyl)(X)]. This approach was used to synthesize the complexes [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 2 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 3 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 4 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Br)] ( 5 ), [Ni(Me₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 6 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 7 ). The complexes 1 to 7 were characterized using NMR and IR spectroscopy and elemental analysis, and the molecular structures are provided for 2 and 7 . The allyl nickel complexes 1 – 7 are stereochemically non-rigid in solution due to (i) NHC rotation about the nickel-carbon bond, (ii) allyl rotation about the Ni–η³-allyl axis and (iii) π–σ–π allyl isomerization processes. The allyl halide complexes can be methylated as was demonstrated by the methylation of a number of the complexes [Ni(NHC)(η³-allyl)(X)] with methylmagnesium chloride or methyllithium, which led to isolation of the complexes [Ni(Me₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 8 ), [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 9 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 10 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 11 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Me)] ( 12 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 13 ). These complexes were fully characterized including X-ray molecular structures for 10 and 11 .     

The synthesis,characterization and melting properties of thiophene-containing dithiocarboxylate complexes of nickel(II)

The reactions of a series of 5-alkyl-2-thiophenedithiocarboxylates with nickel(II) chloride afforded two types of complexes, blue nickel(II) complexes with two terminal dithiocarboxylate ligands, [Ni(S₂CTR)₂] and violet nickel(II) complexes with perthio- and dithiocarboxylate ligands, [Ni(S₂CTR)(S₃CTR)] (where T = 2,5-disubstituted thiophene, R = C_nH_2n+1, n = 4, 6, 8, 12, 16). The blue monomers are preferred for the shorter chains (C₄ and C₆) and the violet compounds form exclusively for the longer chains (C₈, C₁₂, and C₁₆) in the alkylthiophene complexes. In addition to the above series, [Ni(S₂CTCH₃)₂], was prepared in a one-pot reaction in THF and both the blue and violet products were isolated. It was possible to convert the blue complexes [Ni(S₂CTR)₂] (R = butyl, hexyl) into the corresponding violet complexes [Ni(S₂CTR)(S₃CTR)] after stirring in THF solutions for prolonged periods of time. Liquid-crystalline properties of these complexes were examined by DSC and POM. The violet complexes with C₈ and C₁₂ alkyl chains showed liquid-crystalline properties.     

Nickel(II) N‐Benzyl‐N‐methyldithiocarbamato Complexes as Precursors for the Preparation of Graphite Oxidation Accelerators

The nickel(II) N‐benzyl‐N‐methyldithiocarbamato (BzMedtc) complexes [Ni(BzMedtc)(PPh₃)Cl] ( 1 ), [Ni(BzMedtc)(PPh₃)Br] ( 2 ), [Ni(BzMedtc)(PPh₃)I] ( 3 ), and [Ni(BzMedtc)(PPh₃)(NCS)] ( 4 ) were synthesized using the reaction of [Ni(BzMedtc)₂] and [NiX₂(PPh₃)₂] (X = Cl, Br, I and NCS). Subsequently, complex 1 was used for the preparation of [Ni(BzMedtc)(PPh₃)₂]ClO₄ ( 5 ), [Ni(BzMedtc)(PPh₃)₂]BPh₄ ( 6 ), and [Ni(BzMedtc)(PPh₃)₂]PF₆ ( 7 ). The obtained complexes 1 – 7 were characterized by elemental analysis, thermal analysis and spectroscopic methods (IR, UV/Vis, ³¹P{¹H} NMR). The results of the magnetochemical and molar conductivity measurements proved the complexes as diamagnetic non‐electrolytes ( 1 – 4 ) or 1:1 electrolytes ( 5 – 7 ). The molecular structures of 4 and 5· H₂O were determined by a single‐crystal X‐ray analysis. In all cases, the Ni^II atom is tetracoordinated in a distorted square‐planar arrangement with the S₂PX, and S₂P₂ donor set, respectively. The catalytic influence of selected complexes 1 , 3 , 5 , and 6 on graphite oxidation was studied. The results clearly indicated that the presence of the products of thermal degradation processes of the mentioned complexes has impact on the course of graphite oxidation. A decrease in the oxidation start temperatures by about 60–100 °C was observed in the cases of all the tested complexes in comparison with pure graphite.     

Reaktionen von Nickel(0)-Komplexen mit p-Chinonen. Bildung phosphinsubstituierter Radikalanionen

(dipy)Ni(COD) react with duroquinone (Dch) or anthraquinone (Ach) to yield the complexes (dipy)Ni(η⁴ -Dch) or (dipy)Ni(η⁴ -Ach). Chloranil (CA), however, reacts as an oxidant and depending on the temperature (dipy)Ni^II(CA^2-) or following an oxidative addition (dipy)Ni^II(Cl)(CAH^-)(THF) are formed.By substitution of (Cy₃P)₂Ni(C₂H₄) the complexes (Cy₃P)Ni(η⁴-Dch) or (Cy₃P)₂Ni(η⁴ -Ach) are obtained, whereas a 1,1-coupling of quinone and the coordinated phosphine proceeds during the reaction between p-benzoquinone of chloranil and (Cy₃P)₂Ni(C₂H₄). By ESR studies it was demonstrated that with Ni(Cy₃P?Ch)₂ or Ni(Cy₃P?CA)₂, resp., complexes are obtained, in which radical anions, which are derived from the product of this 1,1-coupling, are coordinated to low-spin nickel (II). There is a significant difference between (Cy₃P)₂Ni(C₂H₄) and the analogous platinum or palladium complexes, which are substituted by p-benzoquinone while an oxidative addition proceeds with chloranil.     

Cleavage of Carbon Disulfide by n-Propyldiphenylphosphine and Nickel(II) Bromide

Carbon disulfide is cleaved by n-propyldiphenylphosphine and nickel(II) bromide in a one-step process, to form two unprecedented complexes: orange, [Ni(S₂C₂(PⁿPrPh₂)₂)Br(PⁿPrPh₂)]Br⋅CS₂ ( 1 ) and purple [Ni{η²-SC(PⁿPrPh₂)₂}Br(PⁿPrPh₂)]Br⋅0.5CS₂ ( 2 ). Orange ( 1 ) contains a dithiolene-related ligand that results from carbon–carbon bond formation, while purple ( 2 ) contains a remarkable ligand in which two n-propyldiphenylphosphine molecules have added to a carbon atom of a CS unit that is coordinated to nickel.     

Synthesis,Characterization and Anti-oxidative Activity of Cobalt(II), Nickel(II) and Iron(II) Schiff Base Complexes

Six complexes, M(HL)₂ · nH₂O (M=Co, Ni and Fe; n=4) with two ligands, 2-carboxy-benzaldehydebenzoylhydrazone (H₂L¹) and 2-carboxybenzaldehyde-(4′-methoxy)benzoylhydrazone (H₂L²), have been synthesized and characterized on the basis of elemental analyses, molar conductivities, i.r. spectra and thermal analyses. In addition, the suppression ratio for O₂^- (a) and the suppression ratio for OH^· (b) were determined with a 72 spectrophotometer. The 50% inhibition [IC₅₀ (a) and IC₅₀ (b)] of the complexes were studied. This study demonstrated that the complexes have activity in the suppression of O₂^- (a) and OH^· (b). In general, the antioxidative activities increased as the concentration of these complexes increased up to a selected extent. The complexes exhibit more effective antioxidants than the ligands and the series of the ligand (H₂L²) are better than the series of the ligand (H₂L¹) do.     

Nickel(II) complexes of tetradentate NSNO pyridylthioazophenol ligands: Synthesis,characterization and crystal structure

Two sets of nickel(II) complexes of a series of tetradentate NSNO ligands were synthesized and isolated in their pure form. All these complexes, formulated as [Ni(L)Cl]₂ and [Ni(L)(N₃)]₂ [HL = pyridylthioazophenols], were characterized using physicochemical and spectroscopic tools. The solid-state structures of two complexes (1a and 2a) were established by X-ray crystallography. The geometry about the nickel ion of the complexes is octahedral and the complexes are dimeric in nature. In 1, two Ni(II) ions are bridged by two Cl⁻ anions while in 2 they are bridged by two azide ions in a μ-1,1-bridging fashion.     

Extraction of Unprotected Amino Acids by Mixed-Ligand Nickel(II) and Copper(II) Chelates

Summary.  Six mixed-ligand Nickel(II) and Copper(II) chelates with square-planar geometry of the formula [Ni/Cu(O-O)(S-tmpn)]B(C₆H₅)₄ were prepared, where O-O represents acetylacetonate, tropolonate, or hinokitiolate and S-tmpn is (S)-tetramethyl-1,2-propanediamine. The compounds were investigated with respect to their function as receptor for unprotected amino acids, taking advantage of their high solubilities in non-polar organic solvents. In liquid-liquid extraction experiments between a 1,2-dichloroethane phase containing the metal chelates and an aqueous phase containing amino acids (rac-phenylglycine, rac-phenylalanine, or rac-tryptophan), the nickel(II) chelates effectively extracted amino acids from the aqueous phases under neutral conditions, forming octahedral ternary chelates. Received February 19, 2001. Accepted April 2, 2001     

Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross-Coupling Reactions

The C−F bond activation of pentafluoropyridine and 2,3,5,6-tetrafluoropyridine at [Ni(cod)₂] (cod=1,5-cyclooctadiene) in the presence of the phosphine PPh₂(Ind) (Ind=3-methyl-2-indolyl) led to the formation of the nickel(II) fluorido bis(phosphine) complexes trans-[Ni(F)(2-C₅NF₄){PPh₂(Ind)}₂] and trans-[Ni(F)(2-C₅HNF₃){PPh₂(Ind)}₂]. The complexes are characterized by the presence of intramolecular hydrogen bonds between the NH group of the phosphine ligands and the fluorido ligand. Stochiometric model reactions of nickel(II) fluorido complexes with PhB(OH)₂ revealed that the former can be considered as intermediates in Suzuki–Miyaura cross coupling reactions. Catalytic experiments were attempted using 10 mol-% of trans-[Ni(F)(2-C₅NF₄){PPh₂(Ind)}₂] as catalyst and the activities of the PPh₂(Ind) complex were compared to the ones of an analogous nickel(II) fluorido complex, bearing PPh₃ instead of PPh₂(Ind) as ligands. The latter exhibited a somewhat lower catalytic activity suggesting a slight influence of the H-bonds in the outer coordination sphere.     

Facial Coordination Chemistry in Nickel(II) Compounds with Linear Tridentate Ligands: Synthesis,Spectra and Redox Behavior

1:1 and 1:2 nickel(II) complexes of bis(benzimidazole-2-ylmethyl)amine (bbma) bis(benzimidazole-2-ylmethyl)sulfide (bbms), bis(benzimidazole-2-ylethyl)sulfide (bbes) and diethylenetriamine (dien) were prepared and their spectroscopic and redox behavior studied. The stereochemistry of nickel(II) complexes with bbma, bbes, bbms and dien have been analyzed, confirming facial configuration for Ni(bbma)²⁺ ₂ Cu(bbma)²⁺ ₂ and meridional geometry for Ni(dien)²⁺ ₂ and Cu(dien)²⁺ ₂. The factors favoring facial or meridional coordination of these ligands have been studied. For example, the π-bonding ability of benzimidazole at the termini of the tridentate ligand facilitate the facial geometry for the complexes, and the strong σ-donor ability of amine at the termini of the dien ligand favors meridionally coordinated complexes. The electronic spectral results indicate that the ligand field strength of the complexes decreases in the following order: Ni(bbms)²⁺ > Ni(bbes)²⁺ > Ni(bbma)²⁺ > Ni(dien)²⁺, this decreasing order being consistent with the redox potential obtained for these complexes.     

Oxidation of the thiosulfate ion by some iron(III) complexes with phenolate - amide-amine coordination: A comparative kinetic study

The redox reactions of thiosulfate with four iron(III) complexes having phenolate-amide-amine coordination, Fe^III(L){L = 1,2-bis(2-hydroxybenzamido)ethane, L¹; 1,3-bis(2-hydroxybenzamido)propane, L²; 1,5-bis(2-hydroxybenzamido)3-azapentane, L³; and 1,8-bis(2-hydroxybenzamido)3,6-diazaoctane, L⁴} have been investigated in 10% v/v MeOH + H₂O and I = 0.3 mol dm⁻³. At constant pH (~ 4.8) and under pseudo-first order conditions of [S₂O ₃ ²⁻ ] the reaction obeyed the rate law : − d[Fe^III(L)]/dt = k _obs [Fe^III(L)] + k _obs ^′ where k _obs ^′ denotes the observed rate constant of thiosulfate decomposition; k _obs = a[S₂O ₃ ²⁻ ] + b[S₂O ₃ ²⁻ ] _T ² is valid for all the complexes, particularly at pH < 6, while k _obs ^′ = [H⁺][S₂O ₃ ²⁻ ] _T ² is consistent with the rate law for thiosulfate decomposition proposed earlier. The rate data (k _obs) were analysed on the basis of the reactivities of various species of Fe^III(L) generated by the equilibrium protonation of the sec-NH of dien and trien spacer units resulting in the ring opening (for [Fe^III(L³/L⁴)]), and acid base equilibrium of the aqua ligand bound to the iron(III) centre ([Fe^III(L)(OH₂) _n ]). The redox activities, both for second and third order paths, show the ligand dependencies : L⁴<L³<L¹<L² conforming to the fact that the complexes tend to be less susceptible to electron transfer from S₂O ₃ ²⁻ with (i) the increase of the number of chelate rings, (ii) the decrease of overall charge, and (iii) the decrease of ring size offered by the amine moiety (from six membered to five membered one as for [Fe^III(L¹/L²)(OH₂)₂]⁺. There was no evidence for the formation of inner sphere thiosulfato complex, the possibility of the formation of the outer sphere ion-pairs, [Fe(L/HL)(OH₂)n ^+/2+, S₂O ₃ ²⁻ ] with low equilibrium constant value may not be excluded. In view of this, the outer sphere electron transfer (ET) mechanism is the most likely possibility.     

Nickel nitrosyl complexes in a sulfur-rich environment: The first poly(mercaptoimidazolyl)borate derivatives

The diamagnetic nickel mononitrosyl complexes (Tm^R)Ni(NO) (R = Bu^t, p-Tol) and (Bm^R)Ni(PPh₃)(NO) (R = Me, Bu^t) have been readily prepared from Ni(PPh₃)₂(NO)Br and the appropriate Na(Tm^R) or Na(Bm^R) reagents, respectively. These species constitute the first nickel nitrosyl complexes supported by these ligand systems. An X-ray diffraction study of (Tm^p-Tol)Ni(NO) confirmed its pseudo-tetrahedral geometry and the presence of a nearly linear nitrosyl ligand. In contrast, (Bm^Me)Ni(PPh₃)(NO) can be best described as having a trigonal pyramidal geometry, a spatial arrangement unprecedented in nickel nitrosyl chemistry, which is facilitated by the disposition of the Bm^Me ligand and the presence of a weak intramolecular Ni?H–B interaction opposite to the apical triphenylphosphine ligand.     

Molecular Nonlinear Optical Properties of Acceptors Substituted 2,2′‐Bipyridine and 1,10‐Phenathroline Complexes of Nickel Dithiolate

Linear and nonlinear optical properties of two new nickel(diimine)(dithiolate) complexes, nickel(4,4′‐dinitro2,2′‐bipyridyl)(tfd), Ni(NO₂bipy)(tfd) , (tfd = 1,2‐trifluoromethylethene‐1,2‐dithiolate) and nickel(4,7‐diphenyl‐1,10‐phenathroline)(tfd), Ni(dpphen)(tfd) are reported. Ni(NO₂bipy)(tfd) has a potent electronic acceptor substituted on the diimine ligand and exhibits an enhanced molecular first hyperpolarizability (β₀ = ?31 × 10^?30 esu), which is more than three times greater than that (β₀ = ?10 × 10^?30 esu) of Ni(dpphen)(tfd). Ni(NO₂bipy)(tfd) also possesses the longest absorption wavelength, the largest solvatochromic shift, and one of the largest dipole moment changes (‐16 debye from ground to excited state) among nickel(diimine)(dithiolate) complexes. Crystal X‐ray structure of Ni(NO₂bipy)(tfd) is used to compared the π‐bonding structure of central (N=C‐C=N)Ni(S‐C=C‐S) unit with that of previously known nickel(4,4′‐bis(butyloxycarbonyl)‐2,2′‐bipyridyl)(tfd), Ni(CO₂Bubipy)(tfd).     

Untersuchungen zur Alkylierung von Bis-Stilbendithiolato-Komplexen des Ni(II), Pd(II) und Pt(II)

Investigation on the Alkylation of Bis-Stilbendithiolato Complexes of Ni^II, Pd^II, and Pt^II Alkylation reactions of co-ordinated ligands of the type of ethylene-bisthiol R₂S₂C₂²-proceed different depending on the substituents R. The neutral complexes isolated by a alkylation of the nickel bis-chelates (R = phenyl) according to Schrauzer and Rabinowitz and formulated by these authors as mixed ligand chelates of dithiolate and diether, were identified by us as complexes of the monoethers of the ligand. These nickel (II) complexes of the mono-ethers can not be alkylated further by alkyliodides. Oxidative coupling of two ligands yields disulfides which have been identified by mass spectroscopy thus indicating the original position of attack of the alkylating reagent. The formation of bis-monether complexes is reflected by the different charges on the S atoms of the model complex [Ni(CH₃S₂C₂H₂)(S₂C₂H₂)]- obtained from EHT and CNDO calculations. Both possible stereo-isomers have been isolated of the bis-methylmonether complex of Pt(II). Trans-[M((CH₃)(S₂C₂Ph₂))₂] (M = Ni(II), Pd(II)) form CH₂Cl₂ adducts. By treating the Ni-bis complexes of the monoalkylthioethers with iodine polyiodides are prepared. Binuclear Pd(II) complexes of composition [Pd₂((R)(S₂C₂Ph₂))₂Cl₂] could be prepared by metal exchange.     

MII-N-diisopropoxythiophosphorylthiobenzamide complexing processes in M2[Fe(CN)6]-gelatin-immobilized matrices (M = Co,Ni, Cu)

Complexing processes in M^II-N-diisopropoxythiophosphorylthiobenzamide binary systems (M = Co, Ni, Cu) in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices upon contact with aqueous–alkaline (pH = 12.0 ± 0.1) solutions of organic compounds have been studied. It has been shown that, in Co^II and Cu^II, the initial act of complexing involves destruction of the Co^II and Cu^II hexacyanoferrates(II) by OH^– ions, leading to formation of the corresponding hydroxides which react with the ligand indicated. In the both systems, successive addition of two ligand molecules per M(OH)₂ fragment occurs and [MB(OH)(OH₂)] and [MB₂] coordination compounds are formed (B^–-a singly deprotonated ligand form). In the Ni^II-N-diisopropoxythiophosphorylthiobenzamide system, the formation of three complexes, (Ni₂BOH)₂[Fe(CN)₆], [NiB(OH)(OH₂)] and [NiB₂] occurs.     

Complexes of NS and NSO donor ligands. Nickel(II), copper(II) and cobalt(II) complexes of glyoxal bis(morpholineN-thiohydrazone) and diacetyl bis(morpholineN-thiohydrazone)

Summary Reactions of glyoxal bis(morpholineN-thiohydrazone), H₂gbmth, with NiCl₂·6H₂O, Ni(OAc)₂·4H₂O, Ni(acac)₂· H₂O, CuCl₂·2H₂O, Cu(OAc)₂·H₂O, Cu(acac)₂, CoCl₂· 6H₂O, Co(OAc)₂·4H₂O and Co(acac)₂·2H₂O yield complexes of the type [M(gbmth)], [M=Ni^II, Cu^II or Co^II]. Diacetyl reacts with morpholineN-thiohydrazide in the presence of nickel salts to yield [Ni^II(dbmth)], [Ni^II(dmth)(OAc)]H₂O and [Ni^II(Hdmth)(NH₃)Cl₂] involving N₂S₂ and NSO donor ligands. Copper and cobalt complexes of N₂S₂ and NSO donor ligands with compositions [Cu^II(dbmth)], [Co^II(dbmth)]·4H₂O and [Co^II(H₂dbmth)]Cl₂, have been isolated. The compounds have been characterised by elemental analyses, magnetic moments, molar conductance values and spectroscopic (electronic and infrared) data.     

Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole

Summary Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole Ni(DTZ)X₂ (X = Cl or Br) and M(DTZ)₂X₂ (M = Ni, X = 1 or N03; M = Cu, X = Cl, Br or NO₃) have been prepared. The i.r. spectra show that in all the complexes the ligand is N,N- or N-bonded to the metal while the sulfur atom does not participate in coordination, and that the halide ions are coordinated forming terminal M-X bonds. The NO ₃ ^- group is coordinated in both the nitrato complexes. Magnetic moments of 3.07–3.29 B.M. for the nickel(II) and 1.86–1.92 B.M. for the copper(II) complexes were observed. The Ni(DTZ)X₂ complexes have a pseudo-tetrahedral [N₂X₂] coordination with N,N-bridging ligand molecules. The Ni(DTZ)₂X₂ and Cu(DTZ)₂X₂ complexes, with predominantly monodentate ligand, involve six-coordinate metal atoms with strong equatorial [N₂X₂] bonds and weaker axial bonds.Author to whom all correspondence should be directed.