Cross nickel salt

Modem cross coupling chemistry is heavily dominated by the use of palladium and nickel complexes as the catalysts, which show an impressively wide scope and an excellent compatibility with many functional groups.2 This favorable application profile usually overcompensates the disadvantages resulting from the high price of the palladium precursors, the concerns about the toxicity of nickel salts, the need for ancillary ligands to render the complexes sufficiently active and stable, and the extended reaction times that are necessary in certain cases. 

Metallic monoliths made of both rhodium ([HCR 1]) and FeCrAlloy (72.6% Fe, 22% Cr and 4.8% Al ([HCR 3]) carrying micro channels of 120 pm x 130 pm cross-section at various length (5 and 20 mm) were applied. The monoliths were prepared of micro structured foils by electron beam welding. After bonding, the FeCrAlloy was oxidized in air at 1 000 °C for 4 h to form an a-alumina layer, which was verified by XRD. Its thickness was determined as < 10 pm by SEM/EDX. The alumina layer was impregnated with rhodium chloride and alternatively with a nickel salt solution. The catalyst loading with nickel (30 mg) was much higher than that with rhodium (1 mg) (see Table 2.4). The amount of rhodium on the catalyst surface was determined as 3% by XPS. 

Air-stable sterically congested phosphine oxides such as 48 are also excellent Ug-ands for the nickel-catalyzed cross-coupling of aryl fluorides [43] (Scheme 5.8). The association of nickel salts with these so-caUed heteroatom-substituted secondary phosphine oxide (HASPO) ligands leads to species reactive enough to activate the generally inert arene-fluorine bond (BDE Ph-F = 126kcalmol ). This improved reactivity has been explained by the formation of a bimetallic species 52 (Scheme 5.8), which facilitates the oxidative insertion step that proceeds via transition state TSl (Figure 5.1) [44]. 

In addition to the synthesis of achiral phosphines, cross-coupling chemistry has been extended to a wide array of chiral phosphines [321-327]. An example of this chemistry used common nickel salts to promote the conversion of a steroid-derived bis-triflate species into a bisphosphine (Example 4.35) [328]. 

Specification for electroplated coatings of 65/35 tin/nickel alloy Method for the evaluation of results of accelerated corrosion tests on metallic coatings Methods of test for paints Cross-cut test Pull-off test for adhesion Resistance to artificial weathering (enclosed carbon arc) and Addendum No. 1 Resistance to continuous salt spray Notes for guidance on the conduct of natural weathering test... 

Nickel(II) salts are able to catalyze the coupling of Grignard reagents with alkenyl and aryl halides. A soluble 6 -phosphine complex, Ni(dppe)2Cl2, is a particularly effective catalyst.266 The main distinction between this reaction and Pd-catalyzed cross... 

Reversal of the absolute configuration of the product 6 by addition of a zinc salt was observed in the cross-coupling of 2a with 4a catalyzed by 51/Ni [38,39] (Scheme 8F.7). Thus, the cross-coupling of the Grignard reagents 2a with 4a in the presence of nickel catalyst coordinated with aminoalkylphosphine (S)-51a gave (S)-6 with 61% ee, whereas the reaction of the... 

Nickel/carbene complexes have also been successfully employed in the Suzuki-Miyaura cross-coupling reaction. One of the first successful applications of this was demonstrated by Blakey and MacMillan, wherein boronic acids were coupled with aryltrimethylammonium salts [52]. It was found that the transformation could be accomplished using 10 mol % Ni(COD)2,... 

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