Spin Crossover Induced by Changing the Identity of the Secondary Metal Ion from PdII to NiII in a Face-Centered FeII 8 MII 6 Cubic Cage

Hyunsung Min; Alexander R Craze; Matthew J Wallis; Ryuya Tokunaga; Takahiro Taira; Yutaka Hirai; Mohan M Bhadbhade; Daniel J Fanna; Christopher E Marjo; Shinya Hayami; Leonard F Lindoy; Feng Li

doi:10.1002/chem.202203742

Spin Crossover Induced by Changing the Identity of the Secondary Metal Ion from Pd^II to Ni^II in a Face-Centered Fe^II ₈ M^II ₆ Cubic Cage

Chemistry. 2023 Apr 3;29(19):e202203742. doi: 10.1002/chem.202203742. Epub 2023 Mar 1.

Authors

Affiliations

¹ School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
² Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3Ta, UK.
³ Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan.
⁴ Mark Wainwright Analytical Centre, The University of New South Wales, Kensington, NSW, 2052, Australia.
⁵ Advanced Materials Characterisation Facility, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
⁶ School of Chemistry F11, The University of Sydney, Camperdown, NSW, 2006, Australia.

PMID: 36550089
DOI: 10.1002/chem.202203742

Abstract

Discrete spin crossover (SCO) heteronuclear cages are a rare class of materials which have potential use in next-generation molecular transport and catalysis. Previous investigations of cubic cage [Fe₈ Pd₆ L₈ ]²⁸⁺ constructed using semi-rigid metalloligands, found that Fe^II centers of the cage did not undergo spin transition. In this work, substitution of the secondary metal center at the face of the cage resulted in SCO behavior, evidenced by magnetic susceptibility, Mössbauer spectroscopy and single crystal X-ray diffraction. Structural comparisons of these two cages shed light on the possible interplay of inter- and intramolecular interactions associated with SCO in the Ni^II analogue, 1 ([Fe₈ Ni₆ L₈ (CH₃ CN)₁₂ ]²⁸⁺ ). The distorted octahedral coordination environment, as well as the occupation of the CH₃ CN in the Ni^II axial positions of 1, prevented close packing of cages observed in the Pd^II analogue. This led to offset, distant packing arrangements whereby important areas within the cage underwent dramatic structural changes with the exhibition of SCO.

Keywords: cubic cage; heterometallic; metalloligand; spin crossover; spin transition.