Although nickel-catalyzed stereoconvergent couplings of racemic alkyl electrophiles are emerging as a powerful tool in organic chemistry, to date there have been no systematic mechanistic studies of such processes. Herein, we examine the pathway for enantioselective Negishi arylations of secondary propargylic bromides, and we provide evidence for an unanticipated radical chain pathway wherein o...

Composite coatings of Co–Ni–Al O were studied by electrolytic codeposition of Co–Ni alloys and Al O from a sulfamate 2 3 2 3 electrolyte containing Al O particles. The influence of plating parameters on the content of the co-deposited Al O particles in 2 3 2 3 Co–Ni alloys was investigated. The maximum value of co-deposited Al O can be achieved at a particle content of 80 g l in y1 2 3 bath, a ...

The nature of surface complexes formed on Ni uptake onto montmorillonite (a dioctahedral smectite) has been investigated over an extended time period by polarized extended X-ray absorption fine structure (P-EXAFS) spectroscopy. Self-supporting films of Ni-sorbed montmorillonite were prepared by contacting Ni and montmorillonite at pH 7.2, high ionic strength (0.3 M NaClO4), and low Ni concentra...

Preliminary results of an extended X-ray absorption fine structure (e.x.a.f.s.) and X-ray absorption near edge structure study of jack bean urease have recently been reported [Hasnain & Piggott (1983) Biochem. Biophys. Res. Commun. 112, 279]. These results indicate that the environment of the nickel ion in the enzyme is similar to that in the model compounds Ni(L)2(L')1(ClO4)1 (where L is 1-n-p...

The title ion-pair complex, (C(25)H(20)ClFP)(2)[Ni(C(2)N(2)S(3))(2)], was obtained by the direct reaction of (4-F,2-ClBzTPP)(+)·Br(-) [4-F,2-ClBzTPP(+) is (2-chloro-4-fluoro-benz-yl)triphenyl-phos-pho-nium], NiCl(2)·6H(2)O and Na(2)tdas (tdas(2-) is 1,2,5-thia-diazole-3,4-dithiol-ate) in methanol. The asymmetric unit of the title structure comprises one (4-F,2-ClBzTPP)(+) cation and half of an ...

The influence of humic acid (HA) on Ni(II) sorption to Ca-montmorillonite was examined by using a combination of batch sorption experiments and extended X-ray absorption fine structure (EXAFS) spectroscopy technique. The sorption of Ni(II) on HA-montmorillonite hybrids is strongly dependent on pH and temperature. At low pH, the sorption of Ni(II) is mainly dominated by Ni-HA-montmorillonite and...