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Sulflower

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Sulflower
Ball-and-stick model
Space-filling model
Names
Preferred IUPAC name
1,12:3,4:6,7:9,10-Tetrasulfanocycloocta[1,2-c:3,4-c′:5,6-c′′:7,8-c′′′]tetrathiophene
Other names
Octathio[8]circulene
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C16S8/c17-9-1-2-4-6-8-7-5-3(1)11(18-9)20-13(5)22-15(7)24-16(8)23-14(6)21-12(4)19-10(2)17
    Key: SNTHAZVSUIFTDO-UHFFFAOYSA-N
  • c12c3c4c5c6c7c8c1c9sc2sc3sc4sc5sc6sc7sc8s9
Properties
C16S8
Molar mass 448.66 g·mol−1
Appearance Dark red powder
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Sulflower (a portmanteau of sulfur and sunflower) is a stable heterocyclic octacirculene based on thiophene. Sulflower does not contain any hydrogen. With molecular formula (C2S)8 the compound is considered a type of carbon sulfide. The molecule is flat and together with the 9-membered homolog is at a local strain energy minimum.[1]

Crystal structure
Stacking of sulflower
molecules in the crystal structure
Packing of sulflower
molecules in the crystal structure

Its synthesis (a variation of the Ferrario reaction) is based on deprotonation of a tetrathiophene with lithium diisopropylamide followed by reaction with elemental sulfur to a sulfur-substituted intermediate followed by vacuum pyrolysis.

Sulflower synthesis
Sulflower synthesis

The sulflower molecule has a planar structure with D8h symmetry, i.e., all eight sulfur atoms as well as the two faces of the molecule are undistinguishable. Because of its planar structure, it is predicted to be able to store many hydrogen molecules between the stacks. The conformation of the H2 molecule is calculated to be "standing up" over the five membered rings. Detailed DFT calculations have been performed on these molecules.[2]

References

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  1. ^ Konstantin, Yu. Chernichenko; Sumerin, Viktor V.; Shpanchenko, Roman V.; Balenkova, Elizabeth S.; Nenajdenko, Valentine G. (2006). "Sulflower: A New Form of Carbon Sulfide". Angewandte Chemie International Edition. 45 (44): 7367–7370. doi:10.1002/anie.200602190. PMID 17001717.
  2. ^ Datta, Ayan; Pati, Swapan K. (2007). "Computational design of high hydrogen adsorption efficiency in molecular "Sulflower"". J. Phys. Chem. C. 111 (12): 4487. doi:10.1021/jp070609n.