Acta Crystallographica Section C

Crystal Structure Communications

Volume 59, Part 10 (October 2003)

Acta Cryst. (2003). C59, m407-m412    [doi:10.1107/S0108270103018262]

The isothiocyanate complex of triphenylborane forms an unusual coordination polymer with [K(18-crown-6)]⁺, both in the solid state and in solution

O. Q. Munro and N. Pearson

Abstract: The title salt, (1,4,7,10,13,16-hexaoxacyclooctadecane-⁶O)[(isothiocyanato)triphenylborato-S]potassium(I), [K(C₁₉H₁₅BNS)(C₁₂H₂₄O₆)] or [K(SCNBPh₃)(18-crown-6)], where 18-crown-6 is 1,4,7,10,13,16-hexaoxacyclooctadecane and [SCNBPh₃]^- is the (isothiocyanato)triphenylborate anion, exhibits a supramolecular structure that is best described as a helical coordination polymer or molecular screw. This unusual supramolecular structure is based on a framework in which the SCN^- ion bridges the chelated K⁺ ion and the B atom of BPh₃ in a ₂ fashion. The X-ray crystal structure of the title salt has been determined at 100  (1) and 293  (2)  K. The K⁺ ion exhibits axial ligation by the S atom of the [SCNBPh₃]^- anion, with a K-S distance of 3.2617  (17)  Å (100  K). The trans-axial ligand is an unexpected ²-bound C=C bond of a phenyl group (meta- and para-C atoms) that belongs to the BPh₃ moiety of a neighboring molecule. The K-C bond distances span the range 3.099  (3)-3.310  (3)  Å (100  K) and are apparently retained in CDCl₃ solution (as evidenced by ¹³C NMR spectroscopy). By virtue of the latter interaction, the supramolecular structure is a helical coordination polymer, with the helix axis parallel to the b axis of the unit cell. IR spectroscopy and semi-empirical molecular orbital (AM1) calculations have been used to investigate further the electronic structure of the [SCNBPh₃]^- ion.

Formula: [K(C₁₉H₁₅BNS)(C₁₂H₂₄O₆)]

Online 23 September 2003

	Structure factor file (CIF format) (461.1 kbytes) Contains datablock LT
	Structure factor file (CIF format) (268.0 kbytes) Contains datablock RT

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