Noncovalent Interactions in 2-Mercapto-1-methylimidazole Complexes with Organic Iodides

2-Mercapto-1-methylimidazole (mmim) forms complexes with organic iodides, 1,4-diiodotetrafluorobenzene ( p -F 4 DIB), tetraiodoethylene (TIE), and 1,2-diiodotetrafluorobenzene ( o -F 4 DIB), in which there are remarkably similar N−H···S hydrogen bonding and S···I halogen bonding patterns. Extended chains of alternating donor (mmim) and acceptor ( p -F 4 DIB and TIE) molecules are formed through divalent I···S···I interactions. These chains are joined into double strands through N−H···S interactions that link two mmim molecules into a dimer. In the third complex, N−H···S bound dimers are linked into infinite chains through S···I interactions involving a pair of o -F 4 DIB molecules. Thermal analysis indicates that decomposition in both of the F 4 DIB complexes proceeds through total loss of acceptor, while decomposition of the TIE complex involves a combination of acceptor loss and acceptor reaction. Melting in the o -F 4 DIB complexes appears to be preceded by a solid-state rearrangement or premelting phenomenon that is not observed in the other two complexes. Crystal data for mmim · p -F 4 DIB: monoclinic space group, C 2/ c (no. 15), a = 26.915(3) Å, b = 7.9216(6) Å, c = 14.2630(4) Å, β = 105.618(1)°, V = 2928.7(4) Å 3, Z = 8, ρ calc = 2.34 g/cm 3 . Crystal data for mmim · TIE: monoclinic space group, C 2/ c (no. 15), a = 20.1789(12) Å, b = 10.7824(10) Å, c = 14.5072(2) Å, β = 118.767(1)°, V = 2766.9(3) Å 3, Z = 8, ρ calc = 3.10 g/cm 3 . Crystal data for mmim · o -F 4 DIB: triclinic space group, P 1̄ (no. 2), a = 7.4987(7) Å, b = 8.1906(12) Å, c = 11.6512(12) Å, α = 83.245(4)°, β = 84.695(3)°, γ = 86.135(3)°, V = 706.35(14) Å 3, Z = 2, ρ calc = 2.43 g/cm 3 .