Olefin complexes amination

Nickel(O) reacts with the olefin to form a nickel(0)-olefin complex, which can also coordinate the alkyl aluminum compound via a multicenter bond between the nickel, the aluminum and the a carbon atom of the trialkylaluminum. In a concerted reaction the aluminum and the hydride are transferred to the olefin. In this mechanistic hypothesis the nickel thus mostly serves as a template to bring the olefin and the aluminum compound into close proximity. No free Al-H or Ni-H species is ever formed in the course of the reaction. The adduct of an amine-stabihzed dimethylaluminum hydride and (cyclododecatriene)nickel, whose structure was determined by X-ray crystallography, was considered to serve as a model for this type of mechanism since it shows the hydride bridging the aluminum and alkene-coordinated nickel center [31]. 

The acetylenic diol Me2C(OH)-C C-C(OH)Me2 (ac) forms complexes of the types K PtCl3ac] and cis- and 2mns-[PtCl2(ac)(am)] (am = amine), by reactions commonly used in the preparation of olefin complexes 23, 25,... 

The reactions of iridium olefin complexes are not restricted to reactions with phosphines. Amines have also employed in bridge-splitting and substitution reactions with [Ir(COD)Cl]2, especially chelating diamines. The reactions proceed to yield [Ir(COD)N-N]2 compounds. A fertile chemical area involves the irw(pyrazolyl)borate (see Tris(pyrazolyl)borates) family of compounds with the monoethylene and bisethylene complexes serving as reactive entries in this field. ... 

The dimeric 7r-allylpalladium complex 1 prepared by stoichiometric methoxypalladation of 1,3-cyclohexadiene is aminated with clean inversion of configuration to cis-212. Electron-withdrawing substituents flanking the re-allyl complex generally direct nitrogen nucleophiles to the distal carbon. A similar stereo- and regioselective reaction is seen for the monodentate re-olefin complex 31 Under the conditions used, the intermediate dimethylamino analog of 1 is immediately converted into 4 by attack of excess amine. 

A phosphine-amine pincer ligand reacts with a rhodium olefin complex more easily than diphosphine pincer ligands to give a C-C bond activated complex in minutes at room temperature. In this case, a C-H activated complex was not observed upon monitoring the reaction even at -50°C [55]. 

When Pt-olefin complexes such as PtCl3(olefin) are treated with a second olefin, replacement of the coordinated olefin by the incoming olefin does not result in either double bond migration or (Z), ( ) isomerization of the displaced olefin. However, the olefin complexes when treated at low temperature with a nucleophile such as pyridine (py) or a secondary amine undergo conversion to a or-complex by a stereospecific trans-process, i.e., frans-addition and tra s-elimination. Treatment of frans-LPtCljCZ)-ethylene-l,2-reversible formation of the carbon (7-bonded complex with slow release of pure (Z)-ethylene-l,2-[Pg.383]

Complexes derived from nucleophilic attack on [ / -C5H5Fe(CO)2(olefin)] complexes, hereafter abreviated [Fp(olefin)], are among the most common. Heteroatomic nucleophiles including methanol, dimethylamine, trimethylamine, benzyl amine, t-butylmercaptan, triphenylphosphine and triethylphosphite all react with [Fp(olefin)] complexes to produce stable >/ -alkyliron complexes. Monosubstituted olefin complexes react with methanol with high regiospecificity to produce air-sensitive amber oils, which, however, are well characterized ... 

The cationic olefin complex of Pd(II), [Pd(ij -C5H5XPR3Xethylene)] also reacts with nucleophiles (Nuc) to form Stable / -alkylpalladium(]l) complexes of the type [Pd( j -C5H5XPPh3)(CH2CH2Nuc)] . Both alkoxides and sodium 2,4-pentandionate react in high yield to produce quite stable complexes. The stereochemistry of this addition has been shown to be clearly trans, as is the case with the related Fp(olefin) complexes discussed above. (Both types of complexes are coordinatively saturated, and coordination of the nucleophile prior to addition, a requirement for cis stereochemistry, is not possible.) Amines do not add to the coordinated olefin but displace it to produce [Pd(> -C5H5)(PPh3)(amine)] complexes. 

Reaction of olefin complexes of palladium(ii) with n-butylamine takes place through an intermediate containing both olefin and amine coordinated to the metal. This proposed mechanism contrasts with the reaction of ethylamine with a platinum(ii)-olefin complex, where stereochemical evidence suggests that the amine attacks the olefin directly and is not co-ordinated to the platinum at any stage of the reaction. ... 

The stability of olefin complexes is also sensitive to steric effects. The binding of ethylene is stronger than that of a-olefins in nearly all cases. However, the magnitude of the steric effect on the binding of an olefin depends on the other ligands. For example, the ethylene complex of bis(amine)PdMe in Equation 2.11b is 10-fold more stable than the propylene or hexene complex, while flie ethylene complex of PtClj" is ortiy two-fold more stable than the corresponding propene complex. ... 

Many reactions of amines with palladium- and platinum-olefin complexes have been reported. Akermark showed that nucleophiles add to palladium-olefin complexes to generate aminoalkyl complexes, as shown by the example in Equation 11.26. In this case, reactions of a bis-olefin dichloropalladium complex with amines occurs by splitting of the chloro-bridged dimer by the first equivalent of amine to give a neutral olefin-ligated palladium-amine complex that undergoes attack of the coordinated alkene by a second equivalent of amine. The stereochemistry of the amination is cleanly trans. Akermark and Zetterberg isolated and characterized by C NMR spectroscopy the a-alkyl complexes formed by the amination of both cis- and frans-2-butene, and the stereochemistry of the product alkyl complexes results from external attack by amines, as shown in Scheme 11.5. 

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