2,2 -Bipyridine palladium complex

Bipyridine, palladium complex, 27 319 ruthenium complex, 26 82 tungsten complex, 27 303... 

Bicyclo(2.2.1 )heptane-7-methanesulfonate, 3-bromo-l,7-dimethyl-2-oxo-, ((IB)- endo, anti)]-, ammonium. 26 24 2,2 -Bipyridine, palladium complex, 27 319 ruthenium complex. 26 82 tungsten complex, 27 303... 

N2C10H, 2,2 -Bipyridine, palladium complex, 22 170 mthenium complex, 21 127 NjCioH, 2,2 -Bipyridine, chromium complexes, 23 180 NiC,oH24, 1,2-Ethanediamine, Al,Al -dimethyl-N,N -bis( 1 -methylethyl), platinum complex, 21 88... 

Keywords self-assembly, 4,4 -bipyridine, palladium complex... 

Helquist et al. [129] have reported molecular mechanics calculations to predict the suitability of a number of chiral-substituted phenanthrolines and their corresponding palladium-complexes for use in asymmetric nucleophilic substitutions of allylic acetates. Good correlation was obtained with experimental results, the highest levels of asymmetric induction being predicted and obtained with a readily available 2-(2-bornyl)-phenanthroline ligand (90 in Scheme 50). Kocovsky et al. [130] prepared a series of chiral bipyridines, also derived from monoterpene (namely pinocarvone or myrtenal). They synthesized and characterized corresponding Mo complexes, which were found to be moderately enantioselective in allylic substitution (up to 22%). 

Lehn has also reported the hydrogen-bonding templated assembly of receptors based on bipyridine copper and palladium complexes [102]. A mixture of substituted bipyridines (76, 77) (see Scheme 39) with copper(I) triflate generates a mixture of tetrahedral complexes and uncoordinated ligands. 

Arylzinc species prepared via the sacrificial anode process and from aryl halides in the presence of a nickel 2,2 -bipyridine, as already reported in Section . .1, were found totally unreactive towards common electrophiles such as aldehydes, carboxylic anhydrides or activated alkyl halides. However, they react with some electrophiles when they are activated by the presence of a catalytic amount of copper salts (10 mol% Cul) together with tetramethylethylene diamine (1MEDA) as described by Knochel and Singer on the ArZnX—CuCN metal exchange47 or when the reaction is catalyzed by palladium complex. 

In recent years, many chiral catalysts for the enantioselective synthesis of optical active 1,5-dicarbonyl compounds have been developed, such as chiral crown ethers with potassium salt bases and chiral palladium complexes, including bimetallic systems. Nakajima and coworkers reported on enantioselective Michael reactions of S-keto esters to a,/3-unsaturated carbonyl compounds in the presence of a chiral biquinoline N,N dioxide-scandium complex, which catalyzed the additions in high yields and with enan-tioselectivities up to 84% ee . Kobayashi and coworkers found that the combination of Sc(OTf)3 with the chiral bipyridine ligand 149 (equation 41) was also effective as a chiral catalyst for asymmetric Michael additions of 1,3-dicarbonyl compounds 147 to a,/3-unsaturated ketones 148. The corresponding Michael adducts 150 were obtained in good to high yields with excellent enantiomeric excesses in most cases (Table 10). 

Dendrimers containing a- and metal-bipyridine-bonded platinum and palladium complexes have been prepared.323-327 Puddephatt and co-workers have generated dendrimers containing both palladium and platinum complexes coordinated to bidentate ligands, 276.325 Dendrimer 276 was synthesized via oxidative-addition of a C—Br bond to a platinum complex to form the dendrimer core. Subsequent reaction with metal complexes gave homo- or heterometallic materials. 

For example, the acyl-aryloxo bond cleavage (type b) is shown by the reaction of Ni(cod)2 with phenyl propionate in the presence of PPhs (Scheme 3.34) or 2,2 -bipyridine [65]. The reaction products are ethylene, phenol, and (car-bonyl)nickel complex. Formation of these products is conveniently understood by initial oxidative addition of EtC(0)-0Ph followed by decarbonylation, )S-hydrogen elimination and reductive elimination, though (acyl)(aryloxo)nickel(II) intermediate is not isolated. However, such an intermediate is isolated by the selective insertion of CO into the (alkyl)(aryloxo)nickel (or palladium) complexes, which smoothly affords esters by reductive elimination promoted by electron deficient olehns. The results suggest that the oxidative addition involving C-0 bond cleavage is essentially reversible. 

The UV-visible spectra of the ruthenium complexes show a trend similar to that of the corresponding palladium compounds. Tlie lowest energy n-n transition was observed at 357 nm for 47-3b. MLCT bands were observed in the normal region (ca. 450-470 nm) for typical tris(bipyridine)ruthenium complexes. The proposed structure of 47-3b is shown in Fig. 3.38. 

Platinum (260-262) and palladium (262,263) complexes have been incorporated into dendrimeric materials. Polymers incorporating both platinum and palladium units coordinated to bipyridine ligands have been reported by Pudde-phatt and co-workers (114) (262). These dendrimers were prepared via oxidative addition of a C—Br bond to a platinum complex, giving the core molecule. Further reaction with platinum or palladium complexes resulted in the homo- or heterometallic materials, respectively. 

---