1,2,4,5-Tetrazine: An unprecedented μ4-coordination that enhances ability for anion⋯π interactions

Il'ya A. Gural'skiy, Daniel Escudero, Antonio Frontera, Pavlo V. Solntsev, Eduard B. Rusanov, Alexander N. Chernega, Harald Krautscheid, Konstantin V. Domasevitch

Research output: Contribution to journalArticlepeer-review

120 Scopus citations


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 μ4-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)(H 2O)2(ClO4)2] (4), [Ag 3(Me2ttz)(H2O)2(CF 3SO3)3] (5) and [Cu4Cl 4(Me2ttz)] (6). In 1 and 2, μ4-tetrazines and silver ions (AgN4, Ag-N 2.42-2.53 Å) compose a 3D framework of {42;84} topology. Structures 3 and 4 were based on disilver-tetrazine ribbons, while in 5μ4-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 2.78 Å and O⋯π 2.61 Å. For 6, π-acidity of tetrazine was reflected by contacts Cl⋯π of 3.30 Å. 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.

Original languageEnglish (US)
Pages (from-to)2856-2864
Number of pages9
JournalDalton Transactions
Issue number15
StatePublished - 2009
Externally publishedYes


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