The 1,2,3,5-dithiadiazolyls (R-CNSSN^•, hereafter DTDAs), a family of thiazyl radicals, have been the focus of much investigation due to their potential as building blocks for magnetic and conducting materials. [1] However, these molecules tend to dimerise in the solid state via a spin-pairing interaction known as 'pancake bonding', a two-electron multi-centre interaction between π-radicals [2]. This dimerization renders the resulting materials diamagnetic. Much effort has been devoted to overcoming this interaction to produce magnetic materials.

In order to gain a deeper understanding of pancake bonding, experimental charge density analysis has been carried out on a number of DTDA homodimers, heterodimers and monomers. [3] These data, as well as various computational results, are assessed to probe the nature of the pancake bonds in DTDAs.

1. D. A. Haynes, CrystEngComm, 2011, 13, 4793-4805.
2. H. Z. Beneberu, Y.-H. Tian and M. Kertesz, Phys. Chem. Chem. Phys., 2012, 14, 10713-10725; Cui, H. Lischka, H. Z. Beneberu and M. Kertesz, J. Am. Chem. Soc., 2014, 136, 12958–12965 K. Preuss, Polyhedron, 2014, 79, 1-15.
3. S. Domagała, K. Kość, S. W. Robinson, D. A. Haynes and K. Wozniak, Cryst. Growth Des., 2014, 14, 4834-4848; S. Domagała and D. A. Haynes, CrystEngComm, 2016, 18, 7116-7125; A. B. Voufack, N. Claiser, A. B. Dippenaar, C. Esterhuysen, D. A. Haynes, C. Lecomte and M. Souhassou^, manuscript in preparation.