Aryl embraces

8 Petrukhina, M. A., Designed solvent-free approach toward organometallic networks built on directional metal-Jt-arene interactions , Coord. Chem. Rev. 2007, 251, 1690-1698. 

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Figure 8.72 (a) Sixfold aryl embrace in two X-PPh3 moieties. Hydrogen atoms at the 2 and 3 posi-... 

Dance, L Scudder. M. Supramolecular motifs Sextuple aryl embraces in crystalline [M(2,2 -bipy)3] and related complexes. J. Chem. Soc.. Dalton Trans. 1998, 1341-1350. 

The electrophilic character of the carbonyl group makes it an appropriate substrate for interaction with a variety of nucleophiles. It is by no means limited to simple alkyl- or aryl-magnesium or -lithium reagents of the types considered above. Of special importance are the numerous condensations where carbonyl-containing compounds undergo interaction with enolates. The spectrum of these transformations embraces such classical reactions as the aldol conden-... 

This involves two aryl groups on each molecule, and usually it is centrosyminetric. As shown in Fig. 14a,b, there is an OFF motif between two groups, each of which is also donor in an EF motif. The (OFF)(EF)2 embrace is also named the parallel fourfold phenyl(aryl) einbrace, to differentiate it from the orthogonal fourfold phenyl embrace. (EF)4. " As the size of a heteroaromatic ligand increases, as in eilatin. the OFF motif in the embrace becomes dominant (Fig. 14c), and the association of the complexes [Ru(phen)2(eilatin)] in acetonitrile is measurable. 

This definition is usually extended to embrace polymers in which one or more of the hydrogen atoms in the basic polyalkenamer structure are substituted by alkyl, aryl, halogen or other groups. Thus polybutadiene, polyisoprene and polychloroprene may be considered as particular members of this group. 

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