Preparation and Solid State Characterization of Isostructural Bifunctional 1,2,3,5-Dithiadiazolyls with Benzene, Bithiophene, and Piperazine Spacers

Abstract

The preparation of the bis(1,2,3,5-dithiadiazolyl) radicals [S2N2C]−X−[CN2S2], where X is a heterocyclic bridging group (X = piperazine, thiophene, bithiophene) is described. Crystal structures of the piperazine- and bithiophene-bridged diradicals have been determined by single-crystal X-ray diffraction. The two compounds are isostructural, belonging to the monoclinic space group P21/n; for the piperazine derivative a = 5.9913(6) Å, b = 19.1958(16) Å, c = 9.1244(6) Å, β = 100.314(7)°, and Z = 4. For the bithiophene derivative a = 5.9907(17) Å, b = 24.272(3) Å, c = 9.1740(14) Å, β = 102.961(18)°, and Z = 4. The diradicals associate as cofacial dimers which adopt a herringbone packing pattern analogous to that observed previously for the 1,4-phenylene-bridged derivative. In all three structures the herringbone arrays are characterized by a series of close interdimer S---S contacts along the spine. Consistently, the results of extended Hückel band structure calculations indicate highly developed two-dimensional electronic structures.

Crystal engineering with dithiadiazolyl radicals

“…The diradicals with a piperidine or bithiophene spacer are isostructural to one another and to the 1,4-phenylene-bridged derivative. 61 The structures consist of dimers of radical arranged in a herringbone pattern (Fig. 7a, above).…”

Mass spectrometric studies on small open‐chain piperazine‐containing ligands and their transition metal complexes

“…Piperazine itself is a good hydrogen‐bond acceptor, which together with its metal complexing capabilities makes it an interesting building block for coordination and supramolecular chemistry 6, 7. Among other things, piperazine has been used as a spacer in bis(1,2,3,5‐dithiadiazolyl)radicals,8 antirhinoviral agents,9 buffers in protein analysis,10 and polydentate phosphine ligands 11 . N , N ′‐Dialkyl‐substituted piperazines adopt a chair conformation with N‐substituents in equatorial positions,6 but in some open‐chain metal complexes12, 13 piperazine has been found to exist in a boat conformation.…”

A bimodal dithiadiazolyl diradical: crystal structure and magnetic properties of the 2,2′-dimethylbiphenylene bridged derivative

“…The potential applications of 1,2,3,5-dithiadiazolyl (DTDA) radicals in molecular magnets, 1 conductors 2 and thin film devices 3 has led to increasing interest in both the diversity and control of the structural features of these systems. 4 Most monofunctional derivatives associate in the solid state to afford diamagnetic dimers, and suppression of this dimerization hence represents a major experimental challenge.…”