Group electronic properties

The robust aUyUc Pd-NHC complex XXV (Fig. 5.3) has also been described to catalyze aminocarbonylation of various hetero(aryl) iodides with primary/secondary amines under atmospheric carbon monoxide pressure. This catalyst tolerated a broad range of functional groups, electronic properties, as well as buUdness on hetero(aryl) iodides and amines, affording in aU cases the corresponding amides 77 in good to excellent yields [76]. 

Vogel D, Kruger P and Pollmann J 1997 Structural and electronic properties of group-ill nitrides Phys. Rev. B 55 12 836, and references therein... 

Turning now to electrophilic aromatic substitution in (trifluoromethyl)benzene we con sider the electronic properties of a trifluoromethyl group Because of their high elec tronegativity the three fluorine atoms polarize the electron distribution m their ct bonds to carbon so that carbon bears a partial positive charge... 

H-nmr chemical shifts of N-1—H and N-3—H signals have been used as a criterion for distinguishing between N-l-substituted and N-3-substituted hydantoin derivatives (22). They can often be related to electronic properties, and thus good linear correlations have been found between the shifts of N—H and Hammett parameters of the substituents attached to the aryl group of 5-arylmethylenehydantoins (23). 

Substituents in the indazole ring may direct a given reaction towards another position either by their R and I electronic properties or simply by protecting the most reactive position. Examples of both types are found in sulfonation studies (67HC(22)l). As indicated before (Section 4.04.2.3.2(i)), sulfonation takes place at position 7. However, the presence of an amino group at positions 5 or 7 directs the attack towards the 4-position (Scheme 40). To obtain the indazole-5-sulfonic acid a more complicated procedure has been used but it is still based on the same ideas. 

The electronic properties of the aniline are important in the Doebner reaction. The reaction works best with electronic donating groups. Anilines substituted with a chlorine at the meta position consistently give low yields, but fluorine at the meta position seems... 

As might be expected, the CCI3 group causes signihcant downheld shift both in the and NMR spectra, thus predicting interesting electronic properties for the central q C(H)C1 group. 

Precisely defined collections of different chemical compounds are denominated as chemical libraries that can be efficiently prepared by methods of combinatorial chemistry. Each chemical compound owes specific structural, steiic, and electronic properties that determine all possible interactions of the small molecule with a given protein or receptor. The molecule s properties are based on the steiic arrangement of functional groups, including the conformations that can be attained by a specific structure. 

Kuznetsov and Boldyrev [15] provided theoretical evidence that the 33 , Al3 , and Ga3 anions (lOe) have geometrical (cyclic, planar) and electronic (two delocalized 7t electrons) properties to be considered as aromatic systems. Positive cations of all group XV trimers (14e), P3 " As3 Sb3 and Bi3+, have equilateral-triangular ground states [16]. 

Along these lines, imidazoline [68, 69] rather than oxazoline coordination sites better fitted into a modular concept in order to understand how the electronic properties should ideally be, since electron density can be readily adjusted by the choice of the N substituent [70]. The Cp ligand C5R5 in 47 permits steric and electronic tuning. With the electron-withdrawing effect of five Ph groups R, the... 

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