Alexander J. Blake, Franco Cristiani, Francesco A. Devillanova, Alessandra Garau, Liam M. Gilby, Robert O. Gould, Francesco Isaia, Vito Lippolis, Simon Parsons, Christian Radek and Martin Schröder
The charge-transfer complexes 2[9]aneS3·4I2 ([9]aneS3 = 1,4,7-trithiacyclononane), [12]aneS4·I2 ([12]aneS4 = 1,4,7,10-tetrathiacyclododecane), [14]aneS4·I2, [14]aneS4·2I2 ([14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane), [16]aneS4·I2 and [16]aneS4·4I2 ([16]aneS4 = 1,5,9,13-tetrathiacyclohexadecane) have been prepared by slow evaporation of solutions containing I2 and the appropriate thioether macrocycle in CH2Cl2. The structure of 2[9]aneS3·4I2 shows two independent macrocycles in the asymmetric unit which are linked by a diiodine bridge. Asymmetric units are linked by I · · · I and S · · · I interactions to form an extended array of linked macrocycles. The single-crystal structure of [12]aneS4·I2 features an infinite chain structure formed by alternating [12]aneS4 and I2 molecules. The structure contains both symmetric and asymmetric diiodine bridges. Although the 1∶1 adduct [14]aneS4·I2 can also be described as a one-dimensional infinite chain structure with asymmetric diiodine bridging, the structure is better visualised as alternating layers of macrocycle and iodine spanned by short contacts of 3.335(4) Å. The adduct [14]aneS4·2I2 shows two independent macrocycles each co-ordinated to two I2 molecules. The charge-transfer network consists of chains of molecules with alternating orientations. The single-crystal structure of a third 1∶1 adduct [16]aneS4·I2 contains only symmetrical diiodine bridges between neighbouring macrocycles leading to an infinite chain structure. The compound [16]aneS4·4I2 is the first example of a tetradentate macrocycle which incorporates I2 bound to all four S atoms. The single-crystal structure shows four terminal I2 molecules co-ordinated to the four S donors of the macrocycle. Molecules are linked into interwoven sheets by I · · · I interactions of 3.639(2) Å. The formation enthalpies (ΔH) and constants (K) of 1∶1 adducts obtained by treating various thioether macrocycles with I2 in CH2Cl2 have been determined by electronic spectroscopy. The Fourier-transform Raman spectra for all the charge-transfer adducts have been recorded in CH2Cl2 solutions at different concentrations. The Raman frequencies of the ν(I–I) vibrations show good correlation with the measured formation enthalpies ΔH.