Enaminoketonate complexes

NOs , Cr and DOS (dodecylsulfate). In Figure 2.53, the structure of the LH ligand N-octadecyl-4-tetradecyloxysalicylaldimine is shown. In the complex, three monodentate Schiff base ligands bind in a zwitterionic form to the lanthanide ion. The coordination sphere of the lanthanide ion is completed by coordination to the counter anions. All the complexes [LmILHIsXs] form a smectic A phase. The lowest transition temperatures are observed for the dodecylsulfate complexes.Although the studies of the magnetic anisotropy have been largely been focused on Schiff base complexes, a few data for /3-enaminoketone complexes are available. 

These results are in agreement with some previous work carried out on similar, structurally related enaminoketone complexes (36, 37), and suggest similar explanations [68]. Only enantiotropic nematic phases were formed for complexes 36, which were destabilised as m increased, while complexes 37 showed nematic and Sa phases. 

Enantiotropic mesophase, 4—5 P-enaminoketonate complexes lanthanide crmiplexes, 64-65, 66t structure, 64/... 

Schiff s base ligands, alkyl chains of, 71f smectogenic lanthanide, 72/ P-enaminoketonate complexes lanthanide complexes, 64-65, 66f... 

A different type of indole ring synthesis was accomplished via an intramolecular cyclization of enaminoketones that proceeds through intermediate arylpalladium complexes (90H911). /3-Hydrocarbolines (33) were obtained as the final products. Similar results were obtained in the photo-cyclization of enaminoesters (91TL6129) and enaminolactones (95H1939). Results obtained in the cyclization of A-arylenamines to indoles with... 

The intra-complex PCMU are those compounds in which at least one fragment is linked with the metal ion via both a valent and coordination bond. It should be noted that such compounds can be neutral, cationic, anionic or contain, in addition to chelating ligands, monofunctional varieties. The number of such PCMU is enormous therefore we shall indicate the most frequent types. A detailed consideration has been given earlier to complexes of metals with polymers containing diketone [13], o-hydroxyazomethine [14], enaminoketone [15], amino add [16], 8-hydroxyquinoline [17] and other groups. 

Other reagents recommended for the reduction of isoxazoles to 1,3-enaminoketones include samarium diiodide, molybdenum hexacarbonyl in aqueous acetonitrile, and diiron nonacarbonyl in water. Electrochemical methods have also been employed." A particularly mild method involves reaction with the reduced form of the coenzyme lipoamide (LA2) complexed with iron(II). Birch reduction (sodium and... 

Homonuclear dicopper(II) and dinickel(ll) complexes (Figure 90) of enaminoketonate ligands have been reported to display an enantiotropic Coir phase, which could be supercooled to room temperature [169]. Again the molecules are proposed to associate into dimers to produce an overall disc-like shape although if the R-group is t-butyl then the mesomorphism is lost due to steric hindrance preventing the molecular association. EPR studies with the copper(ll) complexes showed an... 

Related heteropolynuclear complexes 27, based on a non-mesomorphic Fc enaminoketone ligand, were also prepared (27 M = Cu, pj) displayed only monotropic phases Cr 144 (N 122) I for the copper complex... 

Enantiotropic SmA mesophases were obtained in mixed heteropolynuclear complexes containing enaminoketone and or7, ti-palladated imine groups 28 transition temperatures and temperature ranges depended strongly on the nature of the enaminoketone derivative. The trinuclear bis(imine) and the tetranuclear chloro-bridged precursory complexes were also mesomorphic, showing an unidentified smectic phase (Cr 118 S 131 I) and a SmA phase (Cr 238 SmA 248 I) respectively. 

The bi- and trinuclear bis- and tris-cw-enaminoketonato complexes investigated by Pyzuk et al. also represent an interesting approach in designing new molecular species forming liquid crystals, with a perfect control of the location of active sites within the mesophase, thus allowing for specific interactions to take place. The choice of enaminoketone as template ligands was dictated by their relative ease of synthesis, formation of chemically stable mesomorphic complexes vide supra), and facile shape modification. 

Another interesting family of square-planar metallomesogens is that constituted by complexes of enaminoketones. Several copper complexes of type (233a) and (233b), with various n and w, have been synthesized, and when R is an alkoxy (OC H2 +i), alkyl (C H2/j+i), or alkanoate (C02C H2j,+i) group, the complexes are not liquid crystals, or exceptionally showed a monotropic SniA phase. ... 

Similarly, smectic mesophases were obtained in heteronuclear or/ o-palladated imine complexes based on various non-mesomorphic enaminoketone ligands ((263) to (265), Figure 104). The precursor chloro-bridged complex was also mesomorphic, showing an SmA phase between 238 and 248°C. ... 

The closely related oxygen-bridged dicopper complexes based on /3-enaminoketones were also studied ((280) X = H, n= 12, 14, 16, 18). They exhibited an enantiotropic SmA phase typically between the melting point in the range 145-150 °C and the clearing point in the range 160-180 °C. 

TABLE 11 Thermal Behavior of the Lanthanide Complexes P-Enaminoketone L13H of the A/-Alkyl... 

The discussed reactions of carbene and carbyne complexes show that they have essential significance as catalysts or unstable transient intermediate compounds in such catalytic processes as metathesis of olefins and other unsaturated compounds, Fischer-Tropsch synthesis, syntheses of cyclopropanes from diazoalkanes and olefins, and polymerization of olefins and alkynes as well as in organic synthesis. Except for alkynes [reaction (5.132) ] some compounds containing double bonds react with carbon monoxide and carbene ligands to form bonds with those groups. Examples of such compounds are enamines, ynamines, and Schiff bases. The JV-vinylpyrrolidone (enamine), methoxyphenylcarbene, and excess of CO (higher pressure) react to furnish enaminoketone. 

There is evident interest in polymers with reactive end-groups to be used in block copolymerizations. Work with radical systems leading to polymers terminally functionalized with dibenzazepine units or groups such as (CO)jMn has been summarized. Polystyrene has been made with enaminoketone end-groups, which can complex with transition metals. 

Cyclic -enaminoketones are useful intermediates in synthetic chemistry. A new synthesis from jS-diketones and amines (low-boiling amines can be employed with no disadvantage) utilizes boron trifluoride etherate as complexing agent with advantageous results over previous methodology (Scheme 46). Further... 

Fig. 14 Dyad prepared by direct coupling of a a [Ru(bpy)2] group to porphyrins bearing enaminoketone group (M = or Zn ) b an ethynyl(ferrocenyl)(dppe) complex at the meso-position and c a mthenocene on a M-OEP pyrrole ring...

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