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DC Field | Value | Language |
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dc.contributor.author | Lapidus, Saul H. | - |
dc.contributor.author | Stephens, Peter W. | - |
dc.contributor.author | Fumanal Quintana, María | - |
dc.contributor.author | Ribas Ariño, Jordi | - |
dc.contributor.author | Novoa Vide, Juan J. | - |
dc.contributor.author | DaSilva, Jack G. | - |
dc.contributor.author | Rheingold, Arnold L. | - |
dc.contributor.author | Miller, Joel S. | - |
dc.date.accessioned | 2022-05-04T16:23:41Z | - |
dc.date.available | 2022-07-22T05:10:29Z | - |
dc.date.issued | 2021-07-22 | - |
dc.identifier.issn | 1477-9226 | - |
dc.identifier.uri | http://hdl.handle.net/2445/185375 | - |
dc.description.abstract | To identify the genesis of the differing magnetic behaviors for the ferro- (FO) and metamagnetic (MM) polymorphs of [FeCp*2][TCNQ] (Cp* = pentamethylcyclopentadienide; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) the low temperature (18 ± 1 K) structures of each polymorph were determined from high-resolution synchrotron powder diffraction data. Each polymorph possesses chains of alternating S = 1/2 [FeCp*2]˙+ cations and S = 1/2 [TCNQ]˙+, but with differing relative orientations. These as well as an additional paramagnetic polymorph do not thermally interconvert. In addition, the room and low (<70 ± 10 K) temperature structures of the MM polymorph, MMRT and MMLT, respectively, differ from that previously reported at 167 K (−106 °C) MM structure, and no evidence of either phase transition was previously noted even from the magnetic data. This transition temperature and enthalpy of this phase transition for MMRT ⇌ MM was determined to be 226.5 ± 0.4 K (−46.7 ± 0.4 °C) and 0.68 ± 0.04 kJ mol−1 upon warming, respectively, from differential calorimetry studies (DSC). All three MM phases are triclinic (P[1 with combining macron]) with the room temperature phase having a doubled unit cell relative to the other two. The lower temperature phase transition involves a small rearrangement of the molecular ions and shift in lattice parameters. These three MM and FO polymorphs have been characterized and form extended 1-D chains with alternating S = 1/2 [FeCp*2]˙+ cations, and S = 1/2 [TCNQ]˙− anions, whereas the fifth, paramagnetic (P) polymorph possesses S = 0 π-[TCNQ]22− dimers. At 18 ± 1 K the intrachain Fe⋯Fe separations are 10.738(2) and 10.439(3) Å for the FO and MMLT polymorphs, respectively. The key structural differences between FO and MMLT at 18 ± 1 K are the 10% shorter interchain N⋯N and the 2.8% shorter intrachain Fe⋯Fe separation present for MMLT. Computational analysis of all nearest-neighbor spin couplings for the 18 K structures of FO and MMLT indicates that the intrachain [FeCp*2]˙+⋯[TCNQ]˙− spin couplings (H = −2Si·Sj) are the strongest (4.95 and 6.5 cm−1 for FO and MMLT, respectively), as previously hypothesized, and are ferromagnetic due to their S = 1/2 spins residing in orthogonal orbitals. The change in relative [TCNQ]˙−⋯[TCNQ]˙− orientations leads to a computed change from the ferromagnetic interaction (0.2 cm−1) for FO to an antiferromagnetic interaction (−0.1 cm−1) for MMLT in accord with its observed antiferromagnetic ground state. Hence, the magnetic ground state cannot be solely described by the dominant magnetic interactions. | - |
dc.format.extent | 15 p. | - |
dc.format.mimetype | application/pdf | - |
dc.language.iso | eng | - |
dc.publisher | Royal Society of Chemistry | - |
dc.relation.isformatof | Versió postprint del document publicat a: https://doi.org/10.1039/d1dt02106k | - |
dc.relation.ispartof | Dalton Transactions, 2021, vol. 50, p. 11228-11242 | - |
dc.relation.uri | https://doi.org/10.1039/d1dt02106k | - |
dc.rights | (c) Lapidus, Saul H. et al., 2021 | - |
dc.source | Articles publicats en revistes (Ciència dels Materials i Química Física) | - |
dc.subject.classification | Ferromagnetisme | - |
dc.subject.classification | Polimorfisme (Cristal·lografia) | - |
dc.subject.other | Ferromagnetism | - |
dc.subject.other | Polymorphism (Crystallography) | - |
dc.title | Low temperature structures and magnetic interactions in the organic-based ferromagnetic and metamagnetic polymorphs of decamethylferrocenium 7,7,8,8-tetracyano- p-quinodimethanide, [FeCp*2]¿+[TCNQ]¿− | - |
dc.type | info:eu-repo/semantics/article | - |
dc.type | info:eu-repo/semantics/acceptedVersion | - |
dc.identifier.idgrec | 714202 | - |
dc.date.updated | 2022-05-04T16:23:41Z | - |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | - |
Appears in Collections: | Articles publicats en revistes (Ciència dels Materials i Química Física) Articles publicats en revistes (Institut de Química Teòrica i Computacional (IQTCUB)) |
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File | Description | Size | Format | |
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714202.pdf | 13.09 MB | Adobe PDF | View/Open |
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