1. 1,2,4,5-Tetrazine: an unprecedented µ4-coordination that enhances ability for anion …π interactions.
- Author
-
Gural'skiy, Il'ya A., Escudero, Daniel, Frontera, Antonio, Solntsev, Pavlo V., Rusanov, Eduard B., Chernega, Alexander N., Krautscheid, Harald, and Domasevitch, Konstantin V.
- Subjects
- *
TETRAZINE , *COORDINATION compounds , *ANIONS , *COORDINATION polymers , *LIGANDS (Chemistry) , *COPPER chlorides - Abstract
A series of framework coordination polymers reveals the use of 1,2,4,5-tetrazines as efficient bridging ligands towards silver(I) and copper(I) ions. All four nitrogen atoms were functional as lone pair donors leading to an unprecedented m4-coordination of the ligands (1,2,4,5-tetrazine, ttz; 3,6-dimethyl-1,2,4,5-tetrazine, Me2ttz) in [Ag(ttz)(X)] (X = NO3, 1; ClO4, 2), [Ag2(Me2ttz)(NO3)2] (3), [Ag2(Me2ttz)(H2O)2(ClO4)2] (4), [Ag3(Me2ttz)(H2O)2(CF3SO3)3] (5) and [Cu4Cl4(Me2ttz)] (6). In 1 and 2, μ4-tetrazines and silver ions (AgN4, Ag-N 2.42-2.53Å ) compose a 3D framework of {42;84} topology. Structures 3 and 4 were based on disilver-tetrazine ribbons, while in 5 μ4-tetrazines interconnect silver-triflate chains. In 6, μ4-ligands connect inorganic layers sustained by copper-chloride squares, hexa- and octagons (1.974(2) and 1.981(2)Å ). Multiple N-coordination to metal ions enhances the ability of the electron deficient tetrazine system for anion … π binding. Compounds 1 and 2 exhibit very short interactions of this type with corresponding O… C(N) separations down to a record value of 2.78Å and O… π 2.61Å . For 6, π-acidity of tetrazine was reflected by contacts Cl … π of 3.30Å . Results of high level ab initio calculations (RI-MP2/aug-cc-pVTZ) were in good agreement with experimental results, and were suggestive of the progressive enhancement of the π-acidity by increasing the number of Ag(I) ions N-coordinated to tetrazine. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF