Cobalt complexes boron ligands

Chromium dioxide, 928 Chromium fluoride, 932 Chromium tetrafluoride, 927 Chromium trioxide, 941 Chromyl bromide, 940 Chromyl chloride, 940 Chromyl halides, 933, 935, 938 Chromyl nitrate, 940 Chromyl perchlorate, 940 CitratoteUurates, 303 Cobalt complexes boron ligands, 99 Cobalt(ll) complexes reduction... 

Certain cobalt(II) complexes such as the cobaloxime XXVIIa and the corresponding boron fluoride XXVIIb (L is a ligand) terminate propagating chains by a transfer reaction called... 

Clathrochelates comprise a new type of coordination compound containing a metal ion both coordinately saturated and encapsulated by a single ligand.1 5 The ligands of one class of clathrochelates are derived from dioximes and various boron compounds.1,4 Typical examples of iron and cobalt clathrochelates of this structural class are shown in Fig. 19 and Table I. These complexes are readily prepared from iron(II) or cobalt(II) salts,... 

One of the most intensely studied boracychc compound is the borabenzene ligand synthesized by Her-berich and coworkers. Bis- and monoborabenzene cobalt sandwich complexes were first obtained by treating cobaltocene with boron trihalides BX3 (R = Cl, Br) or alkyl/arylboron dihalides (R = alkyl, aryl) as outlined in... 

The calculated ligand field parameters are close to the values obtained for low-spin macrocyclic polyamines and clathrochelate boron-capped cobalt(III) tris-dioximates (see above). The ligand field strength in trichlorotin-capped cobalt(III) tris-dioximates is substantially higher than that in nonmacrocyclic and tribromotin-capped complexes and slightly exceeds that in their boron-capped analogs [44],... 

Similar reactions of norbornadiene with substituted buta-1,3-dienes in the presence of cobalt catalysts lead to the corresponding 1,4-adducts in 92-96% yield.In the presence of chiral phosphane ligands, this reaction has been brought about with up to 79% enantiomeric excess. The head-to-head dimer of norbornadiene, 1,2,4 5,6,8-dimethano-5-indacene (3, Binor-S ) was formed in quantitative yield on dimerizing norbornadiene with catalysts such as co-balt(II) bromide/triphenylphosphane, cobalt(ll) iodide/triphenylphosphane, or (triphenylphos-phanejrhodium chloride, in the presence of boron trifluoride-diethyl ether complex. ... 

Nickel compounds can also be employed as catalysts [161-170]. A three-component system consisting of nickel naphthenate, triethyl-aluminum, and boron trifluoride diethyletherate is used technically. The activities are similar to those of cobalt systems. The molar Al/B ratio is on the order of 0.7 to 1.4. Polymerization temperatures range from -5 to 40 °C. On a laboratory scale the synthesis of 1,4-polybutadiene with allylchloronickel giving 89% cis, 7.7% trans, and 3.4% 1,2-structures is particularly simple [8]. In nickel compounds with Lewis acids as cocatalysts, complexes with 2,6,10-dodecatriene ligands are more active than those with 1,5-cyclooctadiene (Table 4) [171]. 

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