Nickel ethylenediamine complexes

Figure 3.4 nickel ethylenediamine complex reacts with acetone to form a nirrin, the four planar positions of the JVz " " bonds templating the reaction. In evolutionary terms, such reactions permitted great strides forward, as simple molecules such as the two above immediately became corrins surrounding the cobalt of vitamin B12 chlorophyll if magnesium and haem if ferrous was at the centre (from R.W. Hay, in An Introduction to Bio-inorganic Chemistry , ed. D.R. Williams, by permission of the Publishers,... 

In this section, the effect of aggregates such as metallomicelles comprised of nickel and hydrophobic diamines on the epimerization of aldoses is outhned. A homologous series of nickel/ethylenediamine complexes of various N,N-dime-thyl-N -alkylethylenediamines (l,l,n -en) was prepared and examined [64], The influence of the hydrophobicity of the Hgand on the epimerization in aqueous media was assessed. The objective of this work was to clarify why differences in hydrophobicity affect the outcome of the epimerization and to characterize the nature of the aggregative metallomicelle. 

It has been known for a long time that thiosulfate is present in normal human urine, but reliable methods for the determination of fairly low concentrations have not been available. A method based on the precipitation of the nickel-ethylenediamine complex of thiosulfate followed by iodometric determination was reported many years ago, but gives according to our experience unreliable results. We have earlier described a simple colorimetric method for determination of thiosulfate, based on the cyanolysis of thiosulfate to thiocyanate by the action of cyanide and cupric ions followed by determination of thiocyanate as its ferric ion complex. Unfortunately, this method is not sensitive enough for direct application to urine and, furthermore, other urinary compounds interfere in the cyanolysis reaction. It may, however, be used for assay of the very... 

In 1965, Breslow and Chipman discovered that zinc or nickel ion complexes of (E)-2-pyridinecarbaldehyde oxime (5) are remarkably active catalyst for the hydrolysis of 8-acetoxyquinoline 5-sulfonate l2). Some years later, Sigman and Jorgensen showed that the zinc ion complex of N-(2-hydroxyethyl)ethylenediamine (3) is very active in the transesterification from p-nitrophenyl picolinate (7)13). In the latter case, noteworthy is a change of the reaction mode at the aminolysis in the absence of zinc ion to the alcoholysis in the presence of zinc ion. Thus, the zinc ion in the complex greatly enhances the nucleophilic activity of the hydroxy group of 3. In search for more powerful complexes for the release of p-nitrophenol from 7, we examined the activities of the metal ion complexes of ligand 2-72 14,15). 

Template condensation reactions of the nickel(II) complex of 3,7-bis(2-aminoethyl)-l,3,5,7-tetraazabicyclo[3.3.1]nonane with formaldehyde and the appropriate primary diamines such as ethylenediamine, 1,4-butanediamine, and p-xylenediamine yield dinickel(II) complexes of bis-heptaazamacrocyclic ligands (716)-(718). Similarly, the dinuclear Ni11 complexes (719) and (720) were prepared by using [Ni(2,3,2-tet)](C104)2, formaldehyde, and NH2—(CH2)ra—NH2 ( = 2, 3, 4, 5, 6, 10) or melamine, respectively. 

The formation in solution of nickel complexes with TV-substituted ethylenediamines has been studied over a long period by many authors.707 Solutions of nickel(II) complexes with TV-substituted diamines often exhibit equilibria between pseudotetrahedral and pseudo-octahedral species. These equilibria are displaced towards the pseudotetrahedral species when the temperature increases. Complexes Ni(TV,TV-Et2en)2X2691 with poorly coordinating anions are thermochromic. This behaviour has been investigated by means of calorimetric and NMR studies.708,709... 

Divalent nickel forms two main types of complexes. The first consists of complexes of the spin-free ( ionic or outer orbital) octahedral type (see also Ligand for their discussion) in which the ligands are principally H2O, NH3, and various amines such as ethylenediamine and its derivates, e.g., Ni(H20>62+. Ni(NH3)e2+, Ni(en)62+. These complexes usually have colors toward the high-frequency side of the spectrum, i.e., violet, blue, and green. The other class consists of tetracovalent square complexes with ligands such as CN, the dioximes and their derivatives, and other chelates, which usually have colors on the low frequency side of the spectrum, i.e., red. orange, and yellow. The structure of the nickel-climethylglyoxime complex is... 

Nickel ethylenediamine nitrate reagent [Ni(NH2.CH2.CH2.NH2)3](N03)2, abbreviated to [Ni(en)3](N03)2. When a neutral or slightly alkaline solution of a thiosulphate is treated with the reagent, a crystalline, violet precipitate of the complex thiosulphate is obtained ... 

The nickel ethylenediamine nitrate reagent is conveniently prepared when required by treating a little nickel chloride solution with ethylenediamine until a violet colour (due to the formation of the complex [Ni(en)3]2+ ion) appears. Concentration limit 1 in 25,000. 

The use of 1,2-diaminopropane instead of ethylenediamine in the condensation on the nickel(II) ion matrix also leads to the formation of the nickel(II) complex with the corresponding semiclathrochelate ligand [161]. 

In a typical preparation, 100 g (0.178 mole) of the linear quadridentate nickel-(II) complex prepared in Section 7-C is placed in 1-L flask. To this is added 150 mL of dry ethylenediamine (dried by distillation over KOH). The resultant slurry is stirred and heated to reflux ( 160°) under a blanket of nitrogen in an oil bath. After about % hour, all the solid dissolves to give a red solution, which is refluxed for an additional 15 minutes or until red crystals form. The solution is... 

Mixed Donors. The 4-methylpyridine adduct of bis-[l-(2-thienyl)-4,4,4-trifluoro-butane-l,3-dionato]nickel(ii) is shown to have weaker co-ordination than the nonadduct by X-ray studies. The crystal structure of bis-(8-amino-2-methylquinoline) nitratonickel(ii) nitrate shows that the nitrato ligand is bidentate (66). A kinetic study has been made of nickel(ii) murexide complex formation in DMS0-MeN02- Nickel(ii) complexes of some optically active ethylenediamine-NN -diacetic acid-type polyaminocarboxylic acids have been prepared and solid-state spectra and t.g.a. recorded. N.m.r. temperature dependence for racemization of Ni(edta) ,... 

In the presence of a nickel (0) complex such as Ni(PPh3)4 the arylation of allylamine occurs in a very low yield (5%). With nickel (II) salts or complexes, the yields are higher and the best results are obtained for bipy2NiBr2 (50%) or to a less extent for phen2NiBr2 (30%). It is noteworthy that Cramer and coll. (ref. 7) pointed out, on the contrary, that "diamines which coordinate strongly to nickel (II) interfered in the reaction of dimethylamine with chlorobenzene and reduced by a factor of ten (ethylenediamine) or even inhibit (o-phenantroline) the arylation". 

Coordinated secondary amines can also be alkylated, but only after deprotonation by a strong base generates a suitable nucleophile. Work on rhodium(III) complexes of ethylenediamine has been extended to nickel(II) complexes of various fully saturated macrocycles such as cyclam (Scheme The methylated cyclam complex is kinetically inert, unlike the isomer with all four methyl groups on the same side of the ring, which is obtained on reaction of the preformed tetramethyl cyclam with nickel ions. 

Nickel(III) complexes with aliphatic diamines have also been obtained by chemical oxidation (X2 and HNOa) and isolated as salts of general formula [Ni(N— N)2X2]Y (N— N = ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminocyclohexane, 2,3-diaminobutane, o-diaminobenzene X = Q, Br Y = C1, Br, NO3, 064). With N— N = ethylenediamine and 1,2-diaminopropane, depending on the exact reaction conditions, both genuine nickel(III) complexes in a tetragon coordination or mixed-valence [Ni (N— N)2NP (N—N)2X2]Y4 (X = Cl Y CIO4) complexes were obtained. ... 

Nickel ethylenediamine nitrate reagent. This reagent should be prepared when required from 2 ml 0.5m nickel chloride solution by adding ethylenediamine dropwise, until a violet colour appears. The colour is due to the formation of the complex ion [Ni(NH2-CH2-CH2-NH2)3] ". ... 

With these restrictions in mind, we shall consider the thermod5mamic data for stepwise complex formation of iron(II) with several diimine ligands and with ethylenediamine (en), listed in Table 6 together with some data on the respective cobalt (II) and nickel(II) complexes. One... 

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