Molecular Iodine Stabilization in an Extended N center dot center dot center dot I-I center dot center dot center dot N Assembly

The adduct [bis(quinoxaline)-2,2',3,3'-disulfide-I(2)](infinity) (Q(2)S(2)center dot I(2))(infinity) can be easily synthesised from the reaction of Q(2)S(2) and I(2) in CH(2)Cl(2) or, in the absence of any solvent, through diffusion of I(2) vapours at 60 degrees C. X-ray diffraction analysis shows the presence of an extended N center dot center dot center dot I-I center dot center dot center dot N assembly in which each I(2) molecule links a Q(2)S(2) molecule at both ends through a nitrogen atom to form a polymeric species; the d(I-I) and d(N-I) bond lengths confirm a very weak nitrogen-iodine interaction at the base of the N center dot center dot center dot I-I center dot center dot center dot N assembly. DFT calculations provide optimised distances for the N center dot center dot center dot I and I-I bonds and explanation for the zigzag chain formation: the mPW1PW functional and the B3LYP hybrid functional with a variety of basis sets for the I atomic species [CRENBL, LANL2DZ, LANL2DZ(d,p), LANL08(d), SBKJC, SBKJC polarised-LFK and Stuttgart RLC] have been tested. Compound 1 proved stable up to nearly 100 degrees C, and the stability is to be mainly attributed to the lattice energy of its polymeric structure then to donor-acceptor stabilisation. The facile insertion of molecular iodine into the Q(2)S(2) network makes this compound an interesting iodine sponge, suitable for I(2) storage; moreover, Q(2)S(2) can easily collect and release I(2)(g) by a temperature-controlled process (60 and 97 degrees C, respectively).