Complex chelated nickel

The 2,2 -bi-l,3-dithiolium cation (78) has been combined with a complex chelated nickel anion to give a highly conducting salt, which probably contains the radical cation (79). ... 

While apparently no metallasilsesquioxane complexes of nickel and palladium have yet been prepared, several literature reports have appeared on platinum compounds containing silsesquioxane ligands. Abbenhuis reported the synthesis and characterization of three platinum(II) complexes stabilized by the chelating diphosphine ligand dppe (= 1,2-bis(diphenylphosphino)ethane) as outlined in Scheme 63. ... 

Thermodynamic contributions to the chelate effect in complexes of nickel(ll) and copperfll)"... 

Other complexes of nickel with a number of chelate ligands of the quinone series are given in refs. 1605-1608. 

The buff-coloured bis chelate formed by 2-aminobenzenethiol (334) can be oxidized in alkaline solution to a blue-coloured complex of nickel(II) which contains the ligand in an oxidized form (Scheme 34).2422,2462 Complex (334) reacts with Mel in acetone affording the six-coordinate complex NiL containing the S-methylated ligand.2452... 

The earliest high-oxidation-state complex of nickel reported was the heteropoly(molybdate) (132, 133) complex [NilvMo90 32]6. which contains nickel(IV) in an octahedral Ni06 coordination environment. There is no evidence for the corresponding nickel(III) species but further work on nickel(IV) complexes of this type has been reported recently (134). Nickel(III) can be prepared in a six-coordinate oxygen donor environment (135) as a tris chelate with 2,2 -bipyridine-l,T-dioxide (bpy02). The complex has a rhombic EPR spectrum and a reduction potential of 1.7 V, from which an estimate of the reduction potential of the ion [Nini(H20)6]3+ of 2.5 V (versus nhe) has been calculated. 

Hydrides of Ni(I) and Ni(II) are known (37). A Ni(II) hydride appears to be an intermediate in the catalysis of olefin isomerization by phosphine complexes of nickel (61). Dilworth (62) has pointed out that stable hydride species are not obtained in model complexes with sulfur ligands. However, they may be possible within the confines of a protein chelate. 

Modular construction of the ternary complex begins with the epitope tag immobilization of Gfly subunits on beads. Scheme A represents the display of > d 1, 4) subunits tethered to the bead, by an epitope tag (hexahistidine or FLAG), with soluble oq subunit completing the hetero-trimer assembly (G-beads). The typical G-bead sample preparation involves the initial capture and immobilization of the fly subunits, on beads bearing chelated nickel or biotinylated M2 anti-FLAG antibodies. The bead samples are then washed and resuspended in buffer. For the anti-FLAG... 

The invertomers of the nitrogen pyramid 1-chloro-2,2-dimethylaziridine have been separated by enantioselective complexation GC on the chiral metal chelate nickel(II)-bis[(3-heptafluorobutanoyl)-( l.R>)-camphorate] (Ni-CAM2) in squalane (Schurig et al., 1979). The resolution of the chiral aziridine into two sharp peaks with a = 1.5 in 45 min at 60° C demonstrated the stereochemical integrity of the invertomers (cf. Figure 6). 

Similar terpy-like tri-imine ligands are N -(2-pyridylmethyl)picolinamidine (ppa) and its two methyl-substituted derivatives meppa and me2ppa 163. These ligands also form six-coordinate bis-chelate complexes of nickel(II) and iron(II). Magnetic... 

Cationic alkyl complexes of nickel and palladium of type (22-XXXII) stabilized by rigid chelating diazadiene (DAD) ligands polymerize 1-alkenes the nickel complex is particularly active.122 The activities are significantly higher than those of neutral nickel complexes. 

Numerous complexes of nickel(II) and nickel(O) catalyze the addition of the Si-H bond to olefins. Among such catalysts are nickel-phosphine complexes, e.g., Ni(PR3)2X2 (where X=C1, I, NO3 R=alkyl and aryl), Ni(PPh3)4, and Ni-(CO)2(PPh3)2, as well as bidentate complexes of NiCl2-(chelate) and Ni(acac)2L (I phosphine), and Ni(cod)2(Pr3)2 [1-5]. A characteristic feature of nickel-phosphine-catalyzed olefin hydrosilylation is side reactions such as H/Cl, redistribution at silicon and the formation of substantial amounts of internal adducts in addition to terminal ones [69]. Phosphine complexes of nickel(O) and nickel(II) are used as catalysts in the hydrosilylation of olefins with functional groups, e.g., vinyl acetate, acrylonitrile [1-4], alkynes [70], and butadiynes [71]. 

Ni-Based Dendritic Catalysts. One of the first reported examples of a metalloden-drimer catalyst32 resulted from the attachment of monoanionic chelating N-C-N -type pincer moieties to the periphery of a carbosilane dendrimer, followed by the complexation of nickel(II) ions.22,23,33,34 These pincer-based carbosilane metallodendrimers (Figure 10.2) have been used... 

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