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s-Block chalcogenoether chemistry – thio- and selenoether coordination with hard Group 2 ions

s-Block chalcogenoether chemistry – thio- and selenoether coordination with hard Group 2 ions
s-Block chalcogenoether chemistry – thio- and selenoether coordination with hard Group 2 ions
A highly unusual series of Group 2 complexes with soft thio- and selenoether coordination, [MI2([18]aneO4E2)] (M = Ca or Sr; E = S or Se), [CaI2([18]aneO2S4)] and [MI2([15]aneO3S2)], has been prepared by reaction of anhydrous MI2 with the macrocycle in dry MeCN solution. The complexes have been characterised via 1H NMR and IR spectroscopy, microanalysis and crystallographic studies which provide unambiguous confirmation of the M–S/Se coordination. The neutral complexes are seven- or eight-coordinate with the iodo ligands cis. The long M–E bond distances of [similar]3.0 Å indicate weak interactions, but they are significantly less than the sum of the van der Waals radii for M and E, and are important in facilitating isolation of the complexes. Trace hydrolysis of [MI2([18]aneO4E2)] and [SrI2([15]aneO3S2)] leads, unexpectedly, to displacement of the iodo ligands rather than the S/Se donor functions, and the resulting dicationic [Ca(H2O)2([18]aneO4S2)]I2, [Sr(H2O)3([18]aneO4S2)]I2·H2O, [Sr(H2O)3([18]aneO4Se2)]I2 and [Sr(H2O)3([15]aneO3S2)]I2 complexes have been structurally characterised, forming eight- and nine-coordinate cations, with all the macrocyclic donor atoms coordinated. Reaction of Ca(CF3SO3)2 with [18]aneO4S2 in anhydrous MeCN solution similarly affords [Ca(CF3SO3)2([18]aneO4S2)], albeit in low yield, also proven crystallographically. Using the MI2 precursors provides a general entry into this area of coordination chemistry of these Group 2 ions, owing in part at least to their higher solubility in the weak donor (weakly competing) MeCN solvent. While CaCl2 reacts with 18-crown-6 either directly in MeCN giving [CaCl2(18-crown-6)], or in the presence of SbCl5 (to form trans-[Ca(MeCN)2(18-crown-6)][SbCl6]2), neither of these routes works with the oxa-thia or oxa-selena crowns
0300-9246
Farina, Paolo
04a0d791-f411-4b3a-816e-9eca7c45b489
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Farina, Paolo
04a0d791-f411-4b3a-816e-9eca7c45b489
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037

Farina, Paolo, Levason, William and Reid, Gillian (2012) s-Block chalcogenoether chemistry – thio- and selenoether coordination with hard Group 2 ions. Dalton Transactions. (doi:10.1039/C2DT31692G). (PMID:23023758)

Record type: Article

Abstract

A highly unusual series of Group 2 complexes with soft thio- and selenoether coordination, [MI2([18]aneO4E2)] (M = Ca or Sr; E = S or Se), [CaI2([18]aneO2S4)] and [MI2([15]aneO3S2)], has been prepared by reaction of anhydrous MI2 with the macrocycle in dry MeCN solution. The complexes have been characterised via 1H NMR and IR spectroscopy, microanalysis and crystallographic studies which provide unambiguous confirmation of the M–S/Se coordination. The neutral complexes are seven- or eight-coordinate with the iodo ligands cis. The long M–E bond distances of [similar]3.0 Å indicate weak interactions, but they are significantly less than the sum of the van der Waals radii for M and E, and are important in facilitating isolation of the complexes. Trace hydrolysis of [MI2([18]aneO4E2)] and [SrI2([15]aneO3S2)] leads, unexpectedly, to displacement of the iodo ligands rather than the S/Se donor functions, and the resulting dicationic [Ca(H2O)2([18]aneO4S2)]I2, [Sr(H2O)3([18]aneO4S2)]I2·H2O, [Sr(H2O)3([18]aneO4Se2)]I2 and [Sr(H2O)3([15]aneO3S2)]I2 complexes have been structurally characterised, forming eight- and nine-coordinate cations, with all the macrocyclic donor atoms coordinated. Reaction of Ca(CF3SO3)2 with [18]aneO4S2 in anhydrous MeCN solution similarly affords [Ca(CF3SO3)2([18]aneO4S2)], albeit in low yield, also proven crystallographically. Using the MI2 precursors provides a general entry into this area of coordination chemistry of these Group 2 ions, owing in part at least to their higher solubility in the weak donor (weakly competing) MeCN solvent. While CaCl2 reacts with 18-crown-6 either directly in MeCN giving [CaCl2(18-crown-6)], or in the presence of SbCl5 (to form trans-[Ca(MeCN)2(18-crown-6)][SbCl6]2), neither of these routes works with the oxa-thia or oxa-selena crowns

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e-pub ahead of print date: 11 September 2012
Organisations: Chemistry

Identifiers

Local EPrints ID: 345264
URI: http://eprints.soton.ac.uk/id/eprint/345264
ISSN: 0300-9246
PURE UUID: 5f157d41-27be-4ea4-a4d9-d51b184ace57
ORCID for William Levason: ORCID iD orcid.org/0000-0003-3540-0971
ORCID for Gillian Reid: ORCID iD orcid.org/0000-0001-5349-3468

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Date deposited: 14 Nov 2012 15:07
Last modified: 18 Feb 2021 16:34

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Author: Paolo Farina
Author: William Levason ORCID iD
Author: Gillian Reid ORCID iD

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