Crystal structure of 2,2″:6′,2″-terpyridine 1,1″-dioxide 1,2,4,5-tetracyanobenzene, C15H11N3O2 · C6H4(CN)4

Abstract

Source of materialWe have prepared the title compound as a continuing effort to understand the intermolecular contact preferences of the N-oxide group in molecular crystals [1][2][3][4]. 2,2¢:6¢,2²-Terpyridine 1,1²-dioxide was prepared using a modification of the procedure for direct oxidation of pyridine and pyrazine moieties [5]. Dimethyldioxirane (17.71 ml, 0.08 M) in acetone was stirred with terpyridine (150.4 mg, 0.6447 mol, Aldrich 98 %) in acetone (2 ml, Fisher reagent grade) for 5 d at 300 K. Filtration of the mixture provided terpyridine dioxide as a colorless solid (92.2 %, 157.6 mg; m.p. 502 507 K, cf. 505 506 K [6]). The title cocrystals were obtained by slow evaporation of a 1:1 mixture using the previously prepared 2,2¢:6¢,2²-terpyridine 1,1²-dioxide and commercially available 1,2,4,5-tetracyanobenzene in methylene chloride solution at room temperature. The oxidizing agent, dimethyldioxirane, was prepared by reacting potassium peroxomonosulfate (0.0390 mol) and NaHCO3 (0.138 mol) in acetone (38.4 ml) and water (50 ml) [7]. Vigorous stirring of the mixture at 263 K followed by distillation (40 100 Torr) at ambient temperature resulted in 0.06 0.08 M dimethyldioxirane as verified by titration against thioanisole. Experimental detailsThe aryl hydrogen atoms were located in a difference density map and refined isotropically. The CH distances were normalized to 1.08 Å for subsequent investigation of CH···O interactions. DiscussionThe crystal structure of this 1:1 bimolecular compound contains tetracyanobenzene (TCNB) and terpyridinedioxide (TPDO) molecules positioned on inversion and two-fold rotation symmetry elements, respectively. Inspection of molecular conformation reveals the expected planar TCNB with TPDO skewed due to the pyridyl-N-oxide-pyridyl geometry (ÐN10C9C8N1 = 145.7(1)°). The crystal structure is stabilized by an assortment of nonbonded contacts that link adjacent TCNB and TPDO building blocks. Each TCNB moiety forms C2AH···O15 N10