ChemInform Abstract: 1,2,3,5‐Diselenadiazolyls as Building Blocks for Molecular Metals. Preparation and Structures of (PhCN2Se2)+PF‐ 6 and (PhCN2Se2)2.

Belluz, Paul Del Bel; Cordes, A. W.; Kristof, Eva; Kristof, Peter V.; Liblong, S. W.; Oakley, Richard T.

doi:10.1002/chin.199013247

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“…The synthesis of the diselenadiazolyl radicals 2a−2f followed a method similar to that used to prepare the related DTDA radicals using a mixture of SeCl 4 and elemental selenium as a source of SeCl 2 (Scheme 1). 18 This source of SeCl 2 is preferred over a 1:1 mixture of Ph 3 Sb and SeCl 4 , which, in our hands, has, on occasion, been violently exothermic when mixed together in the solid state. Reduction of the sparingly soluble chloride salt [2]Cl was readily achieved via one-electron reduction in a polar solvent.…”

Section: ■ Results and Discussionmentioning

confidence: 63%

“…Similar spectra were observed at low concentration, indicating that this was not due to dipolar broadening effects but was the result of significant g-tensor anisotropy (vide infra), consistent with previous observations. 18,20 However, frozen-solution spectra provided well-resolved features reflecting rhombic symmetry, and the frozen-solution EPR spectrum of 2b is shown in Figure 1. The EPR spectrum reveals well-resolved hyperfine coupling to two 14 N nuclei of the g xx component of the spectrum, and 77 Se satellites for both g xx and g zz were directly observed with estimates of additional hyperfine couplings based on the fit to the EPR profile.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

et al. 2016

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The synthesis and structural characterization of a series of perfluoroaryldiselenadiazolyls [DSeDA; p-XCFCNSeSeN (X = F, Cl, Br, CF, NO, and CN for 2a-2f, respectively)] are described. Concentration-dependent solution UV/vis measurements on 2a follow the Beer-Lambert law and the transitions assigned through time-dependent density functional theory (TD-DFT) studies, indicating little propensity for dimerization in solution (10-10 M). Solution electron paramagnetic resonance (EPR) spectra reveal that these radicals exhibit a broad featureless singlet around g = 2.04 but form well-resolved anisotropic EPR spectra in frozen solution, from which spin densities were determined and found to reflect an increase in the spin density at the chalcogen in relation to the corresponding dithiadiazolyl (DTDA) radicals, p-XCFCNSSN. The solid-state structures of 2a and 2d-2f all adopt spin-paired cis-cofacial dimers in which the dimers are held together via multicenter π*-π* "pancake bonding" interactions. Conversely, 2b and 2c exhibit an orthogonal mode of association, which is unique to DSeDA chemistry but which also affords a singlet ground state evidenced by SQUID magnetometry. The more sterically demanding diselenadiazolyl radical 2f was also prepared and exhibits a trans-antarafacial dimerization mode. DFT studies [UPBE0-D3 ccPVTZ-PP(-F)++] on the model radical HCNSeSeN confirm that each dimer is a stable energy minimum on the potential energy surface, reproducing well the experimental geometric parameters with relative stability in the order cis-cofacial > orthogonal > trans-antarafacial. Computational studies reflect stronger dimerization for DSeDA radicals in relation to their sulfur analogues, consistent with the experimental observation: While 2a and 2d are isomorphous with their corresponding DTDA radicals, 2b, 2c, and 2e-2g are all dimeric, in contrast to their DTDA analogues, which are monomeric in the solid-state. A study on 2f reveals that significant geometric strain accumulates in order to support the propensity for both cis dimerization and intermolecular CN···Se interactions. Conversely, p-NCCFCNSSN likely forfeits dimerization in the analogous packing motif in order to release strain but retains the favorable intermolecular CN···S interactions.

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Section: ■ Results and Discussionmentioning

confidence: 63%

Section: ■ Results and Discussionmentioning

confidence: 99%

Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

et al. 2016

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ChemInform Abstract: 1,2,3,5‐Diselenadiazolyls as Building Blocks for Molecular Metals. Preparation and Structures of (PhCN2Se2)+PF‐ 6 and (PhCN2Se2)2.

Abstract: The diselenadiazolium ring system in (III) or (IV), respectively, is accessible in the same way as already known for the thia analogue.

Cited by 1 publication

References 1 publication

Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

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