| Autor: |
Lohrman J; Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States., Vázquez-Montelongo EA; Department of Chemistry , University of North Texas , 1508 W Mulberry Street , Denton , Texas 76201 , United States., Pramanik S; Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States., Day VW; Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States., Hix MA; Department of Chemistry , University of North Texas , 1508 W Mulberry Street , Denton , Texas 76201 , United States., Bowman-James K; Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States., Cisneros GA; Department of Chemistry , University of North Texas , 1508 W Mulberry Street , Denton , Texas 76201 , United States. |
| Abstrakt: |
Experimental and topological analyses of dipalladium(II) complexes with pyrazinetetracarboxamide ligands containing tetraethyl (1), tetrahexyl (2), and tetrakis(2-hydroxyethyl) ethyl ether (3) are described. The presence of two very short O---O distances between adjacent amide carbonyl groups in the pincer complexes revealed two protons, which necessitated two additional anions to satisfy charge requirements. The results of the crystal structures indicate carbonyl O---O separations approaching that of low barrier hydrogen bonds, ranging from 2.413(5) to 2.430(3) Å. Solution studies and quantum topological analyses, the latter including electron localization function, noncovalent interaction, and Bader's quantum theory of atoms in molecules, were carried out to probe the nature of the short hydrogen bonds and the influence of the ligand environment on their strength. Findings indicated that the ligand field, and, in particular, the counterion at the fourth coordination site, may play a subtle role in determining the degree of covalent association of the bridging protons with one or the other carbonyl groups. |
