Activating a high-spin iron(II) complex to thermal spin-crossover with an inert non-isomorphous molecular dopant
[Fe(bpp) ][ClO ] (bpp = 2,6-bis{pyrazol-1-yl}pyridine; monoclinic, 2/ ) is high-spin between 5-300 K, and crystallises with a highly distorted molecular geometry that lies along the octahedral-trigonal prismatic distortion pathway. In contrast, [Ni(bpp) ][ClO ] (monoclinic, 2 ) adopts a more regular...
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| Veröffentlicht in: | Dalton transactions : an international journal of inorganic chemistry Jg. 53; H. 16; S. 6983 |
|---|---|
| Hauptverfasser: | , , , , |
| Format: | Journal Article |
| Sprache: | Englisch |
| Veröffentlicht: |
England
23.04.2024
|
| ISSN: | 1477-9234, 1477-9234 |
| Online-Zugang: | Weitere Angaben |
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| Zusammenfassung: | [Fe(bpp)
][ClO
]
(bpp = 2,6-bis{pyrazol-1-yl}pyridine; monoclinic,
2/
) is high-spin between 5-300 K, and crystallises with a highly distorted molecular geometry that lies along the octahedral-trigonal prismatic distortion pathway. In contrast, [Ni(bpp)
][ClO
]
(monoclinic,
2
) adopts a more regular, near-octahedral coordination geometry. Gas phase DFT minimisations (ω-B97X-D/6-311G**) of [M(bpp)
]
complexes show the energy penalty associated with that coordination geometry distortion runs as M
= Fe
(HS) ≈ Mn
(HS) < Zn
≈ Co
(HS) ≲ Cu
≪ Ni
≪ Ru
(LS; HS = high-spin, LS = low-spin). Slowly crystallised solid solutions [Fe
Ni
(bpp)
][ClO
]
with
= 0.53 (1a) and 0.74 (2a) adopt the
2
lattice, while
= 0.87 (3a) and 0.94 (4a) are mixed-phase materials with the high-spin
2/
phase as the major component. These materials exhibit thermal spin-transitions at
= 250 ± 1 K which occurs gradually in 1a, and abruptly and with narrow thermal hysteresis in 2a-4a. The transition proceeds to 100% completeness in 1a and 2a; that is, the 26% Ni doping in 2a is enough to convert high-spin [Fe(bpp)
][ClO
]
into a cooperative, fully SCO-active material. These results were confirmed crystallographically for 1a and 2a, which revealed similarities and differences between these materials and the previously published [Fe
Ni
(bpp)
][BF
]
series. Rapidly precipitated powders with the same compositions (1b-4b) mostly resemble 1a-4a, except that 2b is a mixed-phase material; 2b-4b also contain a fraction of amorphous solid in addition to the two crystal phases. The largest iron fraction that can be accommodated by the
2
phase in this system is 0.7 ± 0.1. |
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| Bibliographie: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 1477-9234 1477-9234 |
| DOI: | 10.1039/d4dt00443d |