Isomerization of a lanthanide complex using a humming top guest template: a solid-to-solid reaction

Mills, Michelle B.; Hollingshead, Andrew G.; Maahs, Adam C.; Soldatov, D. V.; Preuss, Kathryn E.

doi:10.1039/c5ce01680k

Cited by 11 publications

(6 citation statements)

References 51 publications

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“…All four 4-alkoxy perfluoroaryl carbonitrile derivatives, ROC 6 F 4 CN, were synthesized from a mixture of pentafluorobenzonitrile and sodium alkoxide in the corresponding alcohol based on the literature procedure (see ESI-2). The 4′-alkoxy-functionalized perfluoroaryl DTDA radicals 1–4 were then prepared using standard synthetic methodologies using triphenyl antimony as the reducing agent due to the low melting point of the radicals (60–80 °C), which avoided any contamination with Ph 3 SbCl 2 (mp = 142 °C) during sublimation . In this manner radicals 1 – 4 were obtained in crystalline form in 37–70% recovered yield.…”

Section: Resultsmentioning

confidence: 99%

Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN

Beldjoudi

Sun

Arauzo

et al. 2017

Crystal Growth & Design

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The 4′-alkoxy-tetrafluorophenyl dithiadiazolyls, ROC6F4CNSSN [R = Me (1), Et (2), n Pr (3), n Bu(4)] all adopt cis-oid dimers in the solid state. The methoxy derivative 1 adopts a π-stacked AA’AA’ motif, whereas propoxy (3) and butoxy (4) derivatives exhibit an AA’BB’ stacking. The ethoxy derivative (2) is polymorphic. The α-phase (2α) adopts an AA’BB’ motif comparable with 3 and 4, whereas 2β and 2γ are reminiscent of 1 but combine a mixture of both monomers and dimers in the solid state. The structure of 2β exhibits Z’ = 6 with two dimers and two monomers in the asymmetric unit but undergoes a thermally induced phase transition upon cooling below −25 °C to form 2γ (Z’ = 14) with six dimers and two monomers in the asymmetric unit. The transition is associated with both rotation and translation of the dithiadiazolyl ring. Detailed differential scanning calorimetry and variable temperature powder X-ray diffraction studies coupled with SQUID magnetometry have been used to show that 2α converts irreversibly to 2β upon heating and that 2β and 2γ interconvert through a reversible phase transition with a small thermal hysteresis in its magnetic response.

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Section: Resultsmentioning

confidence: 99%

Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN

Beldjoudi

Sun

Arauzo

et al. 2017

Crystal Growth & Design

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“…The use of silver powder in THF proved successful for both 2b and 2e but, in other cases, formed oily residues from which pure radical could not be isolated by sublimation. The use of Ph 3 Sb in MeCN as an alternative reductant can be successfully ( 2a , 2c , and 2f ) used provided the radical does not sublime at temperatures similar to those of Ph 3 Sb (mp 52–54 °C), which can contaminate the sample or lead to cocrystallization . For volatile radicals or those with a high solvent affinity, the use of Zn/Cu couple in highly volatile liquid SO 2 proved successful ( 2d and 2g ).…”

Section: Resultsmentioning

confidence: 99%

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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“…Reactions of the DTDA radical with divalent metals chelated by strongly electron-withdrawing ligands (hfac – , or 1,1,1,5,5,5-hexafluoroacetylacetonate) have been successful in forming coordination complexes through the heterocyclic N atom. Thus, Preuss and co-workers have investigated the coordination of 4-(2′-pyridyl)- and 4-(2′-pyrimidyl)-1,2,3,5-dithiadiazolyl radicals to several transition metal centers and, more recently, Ce(III) and Ln(III) . The first N-coordinated DTDA metal complex was described in 2004; subsequent work suggested that magnetic coupling between metal ions may be mediated by DTDA ligands, though not in the case of coordination polymers of Mn(II), Co(II), and Ni(II) with 4-(2′-cyanofuryl-5′)-1,2,3,5-dithiadiazolyl as the bridging ligand .…”

Section: Introductionmentioning

confidence: 99%

Cobalt Porphyrin–Thiazyl Radical Coordination Polymers: Toward Metal–Organic Electronics

2017

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Herein we delineate an unusual one-dimensional coordination polymer (CP), 3, prepared from S = 1/2 Co(TPP), 1 (TPP = 5,10,15,20-tetraphenylporphyrin dianion), and S = 1/2 4-(4'-pyridyl)-1,2,3,5-dithiadiazolyl (py-DTDA) radical, 2. The atypically long S-S distance for CP 3 (2.12 Å) reflects fractional electron transfer from the formally Co(II) ion into the antibonding π-SOMO of the metal-bound py-DTDA bridging ligand. The bonding in solid CP 3 involves noninteger redox states in a resonance hybrid repeat unit best formulated as [Co(TPP)] hemication (Co) bound to a dithiadiazolide hemianion (py-DTDA). DFT calculations confirm the metal to ligand charge transfer (MLCT) character of the low-lying electronic states (641, 732, and 735 nm) observed for CP 3 and show that oligomer chains of length ≥14 repeat units tend toward a band structure with a limiting band gap energy of 0.669(6) eV. In dichloromethane, the reaction between radicals 1 and 2 involves coordination of the Co(II) ion by a py-DTDA ring sulfur atom, orbitally favored spin-pairing, and the formation of the thermodynamically favored diamagnetic five-coordinate S-bound adduct, Co(TPP)(S-py-DTDA), 3a. Polymerization and crystallization of 3a affords diamagnetic CP 3. Dissolution of CP 3 in DMSO favors Co-S bond heterolysis, yielding the diamagnetic six-coordinate purple N-bound Co(TPP)(N-py-DTDA)(O═SMe) complex (λ, 436 nm). However, monomerization of CP 3 in dry 1,2-dichloroethane affords bright green diamagnetic Co(TPP)(N-py-DTDA), 3b, with multiple MLCT bands in the 800-1100 nm NIR region and a red-shifted Soret band (λ, 443 nm). Implications for the use of CP 3 in electronic devices are discussed based on its density of states.

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Isomerization of a lanthanide complex using a humming top guest template: a solid-to-solid reaction

Abstract: SbPh3Cl2is used to effect a dramatic rearrangement of the ligand sphere and “pancake bonding” in Ce(hfac)3(5′-Br-pyDTDA)2by forming a 2 : 1 host–guest complex.

Cited by 11 publications

References 51 publications

Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN

Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN

Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

Cobalt Porphyrin–Thiazyl Radical Coordination Polymers: Toward Metal–Organic Electronics

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Isomerization of a lanthanide complex using a humming top guest template: a solid-to-solid reaction

Abstract: SbPh3Cl2is used to effect a dramatic rearrangement of the ligand sphere and “pancake bonding” in Ce(hfac)3(5′-Br-pyDTDA)2by forming a 2 : 1 host–guest complex.

Cited by 11 publications

References 51 publications

Structural Variations in the Dithiadiazolyl Radicals p-ROC6F4CNSSN (R = Me, Et, nPr, nBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC6F4CNSSN

Structural Variations in the Dithiadiazolyl Radicals p-ROC6F4CNSSN (R = Me, Et, nPr, nBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC6F4CNSSN

Structural Studies of Perfluoroaryldiselenadiazolyl Radicals: Insights into Dithiadiazolyl Chemistry

Cobalt Porphyrin–Thiazyl Radical Coordination Polymers: Toward Metal–Organic Electronics

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Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN

Structural Variations in the Dithiadiazolyl Radicals p-ROC₆F₄CNSSN (R = Me, Et, ⁿPr, ⁿBu): A Case Study of Reversible and Irreversible Phase Transitions in p-EtOC₆F₄CNSSN