Nickel 1,4,8,11-tetraazacyclotetradecane

It is well-established that electroreduced nickel(I) complexes of cyclam and a variety of substituted cyclams add oxidatively to alkyl halides to give alkylnickel(III) complexes in organic solvents,251,276 the lifetime of the carbon-nickel bond governing the overall behavior of the system. However, it was shown that [Ni (tmc)]+ (one-electron reduced form of complex (17) tmc= 1,4,8,11-teramethyl 1,4,8,11-tetraazacyclotetradecane) reacts with alkyl chlorides in aqueous alkaline solution in a one-electron process.277,278... 

Ni(04C2)(tet-a)-3H20 (tet = 5,7,7,12,14,14-hexamethyl-l,4,8,ll-tetraazacyclotetradecane a = meso isomer b = racemic isomer) were prepared by the reaction of a concentrated solution of sodium oxalate with an aqueous solution of the appropriate nickel(II) amine complex.1780,1781 In the dinuclear complex [Ni2(04C2)(en)4](N03)2 (234)1740-1741 the bridging oxalato group is planar and symmetrically bonded to the two nickel atoms. The same structure occurs in the complex Ni2(04C2)(0N0)2(py)6 which was obtained as a by-product in a very low yield when a pyridine solution of methanenitrosolic acid and nickel(II) were allowed to stand for several months.1741... 

In the square pyramidal complex [Ni(Me4cyclam)N3](C104) (379) (Me4cyclam is 1,4,8,11-tetramethylT,4,8,ll-tetraazacyclotetradecane) the coordinated azide anion is on the same side of the four methyl groups with the nickel atom 33 pm from the N4 plane. The five- and six-membered chelate rings are in the usual gauche and chair conformations respectively.2681 This complex is labile in comparison with the very inert dinuclear complex... 

Insertion of new ligands into metallocomplex systems may proceed reversibly. Being reduced in the framework of the complex, these ligands lose the ability to be coordinated and leave the coordination sphere as products. One important example of such ligand sliding is the catalytic transformation of C02 into CO. Rhenium, palladium, platinum, and nickel complexes were recommended to catalyze this process (Hawecker et al. 1986 Du Bois Meidaner 1987). The Ni(II) complex with 1,4,8,11-tetraazacyclotetradecane is preferential (Beley and co-authors 1984). 

Dong, Y., Lawrance, G. A., Lindoy, L. F., and Turner, P. (2003) Macrocyclic ligand design. Interaction of a series of successively N-benzylated derivatives of 1,4,8,11-tetraazacyclotetradecane (cyclam) with copper(II) and nickel(II), Dalton Trans. (8), 1567-1576. 

Cyclam, 1,4,8,11-tetraazacyclotetradecane, is a cyclic amine readily synthesized from a linear tetraamine precursor, 1,5,8,12-tetraazaduodecane, which is preorganized by a metal template that promotes square planar complex formation, such as nickel, followed by the addition of ethanedione. Reduction of the Schiff base by a... 

P. V. Bernhardt, P. Comba, and T. W. Hambley, Inorg. Chem., 32, 2804 (1993). Complexa-tion of cis-6,13-Dimethyl-l,4,8,ll-tetraazacyclotetradecane-6,13-diamme with First Row Transition Metal Ions Cobalt(III), Chromium(lll), and Nickel(Il). 

The tetradentate ligand, 1,4,8,11-tetraazacyclotetradecane (cyclam), forms solid diamagnetic orange to brown Ni(II) complexes with iodide and perchlorate anions (9). When the anions are changed to chloride and bromide, the solid complexes are paramagnetic (9). However, all the complexes are soluble in water, methanol, and benzene, giving yellow solutions. The yellow color remains on treatment with 12N HCl and excess chloride ion (9). It is interesting to note that this amine is a derivative of a reduction product of the template syntheses between bis(ethylenediamine)-nickel(II) and acetone reported earlier. 

The worksheet in Figure 23-3 illustrates a case of a reaction so slow that it was necessary to use the Solver to find the final absorbance reading. The unstable czs-octahedral isomer of the nickel(II) complex of the macrocyclic ligand cyclam (1,4,8,11-tetraazacyclotetradecane) isomerizes to the planar complex... 

Typical examples of the rich coordination chemistry of saturated tetraaza macrocycles are the complexes given by 1,4,8,11-tetraazacyclotetradecane, also known as cyclam, with nickel(II) (Table 103). Isomerism is expected to occur in the Ni-cyclam system due principally to the different configurations about the asymmetric coordinated secondary amines which, in turn, influence the possible conformations which can be adopted by the chelate rings. In the tram octahedral complexes [NiX2(cyclam)] (373 X = Cl, and [NiI(cyclam)]I-H20 ... 

The electropolymerization method of functional monomers has proved successful in many cases, in particular to incorporate various ligands and their metallic complexes, like salen [66,245], porphyrin [246], diphosphine [247], pyridine [71,80,248,249], crown ether [250,251], metallofullerene [252], tetraazacyclotetradecane [253], or Prussian blue type [254] in a conjugated organic material like PPy, PTh, or PANE Thick films are likely to be obtained provided that the polymer is redox active at the deposition potential due to this, Zotti et al. demonstrated that 5,5 -bis(3,4-(ethylenedioxy)thien-2-yl)-2,2 -bipyridine could be electropolymerized when complexed by iron and ruthenium, but not in the case of complexation by nickel or copper [71]. 

Kimura, E., S. Wada, M. Shionoya, and Y. Okazaki (1994). New series of multifunctionalized nickel(II)-cyclam (cyclam = 1,4,8,11 tetraazacyclotetradecane) complexes. Application to the photoreduction of carbon dioxide. Inorg. Chem. 33, 770-778. 

Tetraheterodecalin podands, their linkers, and resulting macrocycles A hoard of constitutionally and stereochemically dynamic systems 13IJC45. Thermodynamics and kinetics of CO2, CO, and H binding to the metal centre of CO2 reduction catalysts, in particular, cobalt and nickel complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) and its derivatives 12CSR2036. 

P. A. Christensen, A. Hamnett and S. J. Higgins, In situ FTIR study of charge conduction in a poly(3-methylthiophene)-poly( 1 -[2-(3-thienyl)ethyl]-l, 4,8,11 -tetraazacyclotetradecane nickel(II) perchlorate) copolymer film, J. Chem. Soc., Faraday Trans., 92, 773-781 (1996). 

The basic reaction catalyzed by CODH is related to the water gas shift reaction employed industrially to generate H2 by the reaction of CO and H2O. Industrially the process is iron-catalyzed, and numerous organometallic complexes effect the same reaction [133]. Additionally, square-planar Ni(II) complexes electrocatalyze the reduction of CO2 to CO, including [Ni (cyclam)] (cyclam = 1,4,8,11-tetraazacyclotetradecane), nickel-porphyrins and phthalocyanines. The cluster [Fe4S4(SR)4] and certain Fe-porphyrins also catalyze this reaction [124]. 

There are five basic forms for the trans or planar metal complexes which contain 1,4,8,11-tetraazacyclotetradecane, cyclam, or the hexamethyl analog, CTH. These forms arise due to the combinations of the configurations of the four asymmetric coordinated secondary amine nitrogens present in these systems. Each secondary amine proton is approximately in an axial position and either resides above or below the plane containing the nickel and four nitrogen atoms. Three of these forms are nonenantiomeric (I, II, and III, Fig. 1) and two are enantiomeric (IV and V, Fig. 1). The numerals 3 and 2 in Fig. 1 represent the three and two carbon chains, respectively, which span adjacent coordinated secondary amines. The + and — notation represents secondary amine protons above and below the plane,... 

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