Structures of the macrocyclic polythiaether 1,4,8,11-tetrathiacyclotetradecane and implications for transition-metal chemistry

Conformational studies on [16]aneS4. Structures of α- and β-[16]aneS4 ([16]aneS4 = 1,5,9,13-tetrathiacyclohexadecane)

“…Both [12]aneO4 (Groth, 1978a) and [12]aneS4 (Robinson & Sangokoya, 1988;Cooper, Foxman, Hartman, Storey & Wolf, 1987) adopt square {[3333] in Dale's notation (Dale, 1963)} conformations in the solid state, which is also the form observed in the crystal structure of C12Hz4 (Dunitz & Shearer, 1960) (Cooper, Foxman, Hartman, Storey & Wolf, 1987). The structures of [14]aneO4 (Groth, 1978b), [14]aneS4 (DeSimone & Glick, 1976) and [16]aneO4 (Groth, 1971(Groth, , 1974 exhibit similar features to those above. The tetraprotonated {[14]aneN4H4} 4+ macrocycle also adopts a rectangular conformation in the solid state (Blake, Greig & Schr6der, 1990) while the saturated tetraaza rings [14]aneN4 (Curtis, 1979) and [16]aneN4 (Ekstrand, Raymond & Smith, 1978) show endodentate conformations, similar to those observed in tetragonal metal complexes of these ligands.…”

“…The typical exo conformation of the tetrathia macrocycles can be explained by the mutually gauche placement of the C--S bonds which minimizes S...S repulsions. This observation provides a rationalization for the tendency of tetrathia macrocycles to coordinate to metal ions in an exo manner: endo coordination to yield a complex with the metal ion enclosed within the macrocyclic hole requires reorganization of the ligand conformation (DeSimone & Glick, 1976). This preference contrasts sharply with that of [9]aneS3: the apparent preorganization of this trithia ligand for facial binding to metal centres dominates its coordination chemistry (Blake & Schr6der, 1990).…”

Conformational analysis of 14- and 16-membered unsaturated oxa, thia, and selena macrocyclic ligands

“…Cal-SUGVEV [48] SUGVIZ [48] THCDCU [56] TTCDCU10 [67] TTCDNI [95] TTDNBC 10 [50] PEVNEJ [107] PITVUJ [65] SONPIU [12] SONPOA [12] STHDMO [108] TOCYHX [72] TTHCTD [44] TTPHGC10 [66] VAZRET [83] VIMDOK [59] VURCIU [95] VURCOA [96] VAVNAH [109] VAZSIY [80] VAZSOE [80] VIXPOH [69] VIXPUN [69] VIZPUP [110] culations were performed on the free ligands alone with explicit lone pairs on oxygen donor atoms. The initial structures for minimization were imported from the CSD where suitable examples existed; otherwise the conformation was selected by the temporary imposition of appropriate torsional constraints.…”

Thiols and Sulfides as Complexing Agents and Catalysts

“…6 This causes the heteroatoms to be respectively inside and outside the macrocyclic rings. These effects are reinforced on complexation.…”