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From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Extended structures of polyiodide salts of transition metal macrocyclic complexes
Alexander J Blake1, Wan-Sheung Li, Vito Lippolis
1School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, England. a.j.blake@nottingham.ac.uk
Abstract:
The structures of five polyiodide salts, [Co([9]aneS3)2]I11 (1), [Ni([9]aneS3)2]I6 (2), [Ni([9]aneS3)2]I10 (3), [Pd([12]aneS4)]I6 (4) and [Pd([14]aneS4)]I10.MeCN (5), containing the template cations [Co([9]aneS3)2]3+, [Ni([9]aneS3)2]2+, [Pd([12]aneS4)]2+ and [Pd([14]aneS4)]2+ ([9]aneS3=1,4,7-trithiacyclononane, [12]aneS4=1,4,7,10-tetrathiacyclododecane, [14]aneS4=1,4,8,11-tetrathiacyclotetradecane) exhibit a range of polyiodide and polyanionic framework structures. In (1) the charge on the CoIII cation is balanced by three I3- anions, which along with a neutral di-iodine molecule form I(11)3- rings in an extended structure comprising undulating chains of alternating I11(3-) rings and complex cations. In (2) the complex cation is linked to two tri-iodide anions by S...I interactions into well separated sheets of cations and anions, while in (3), I5- anions are linked by I...I interactions into helices which are cross-linked by S...I contacts to form sheets. Rather longer I...I contacts in (4) assemble I3- ions into 2x2 rods, which are linked into a three-dimensional network by S...I contacts. In (5) the N atom of the acetonitrile solvent molecule forms an array of four weak C-H...N hydrogen bonds to the macrocycle. The extended structure comprises corrugated zigzag chains of polyiodide rings formed by linked I_5;- units; the complex cations are attached to the polyiodide network by S...I contacts, which link the chains to form layers.
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