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Trinuclear Triplesalophen Building Blocks with Terminal Cyanides and Implications for the Spin‐Polarization Mechanism for Low‐Spin Fe III and Cr III Ions
Author(s) -
Oldengott Jan,
Richthofen CarlGeorg,
Walleck Stephan,
Stammler Anja,
Bögge Hartmut,
Glaser Thorsten
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201801042
Subject(s) - chemistry , crystallography , antiferromagnetism , unpaired electron , ligand (biochemistry) , delocalized electron , ferromagnetism , ion , spin polarization , stereochemistry , molecule , electron , condensed matter physics , physics , biochemistry , receptor , organic chemistry , quantum mechanics
In order to further optimize our triplesalen‐based single‐molecule magnets, we have synthesized the triplesalophen ligand H 6 baron Me , where the completely sp 2 ‐hybridized ligand backbone should enable almost planar complexes. Here, we report the new complexes [(baron Me ){Fe III Cl} 3 ], [(baron Me ){Fe III (CN) 2 } 3 ] 3– , and [(baron Me ){Cr III (CN) 2 } 3 ] 3– . As intended the local anisotropy axes, defined by the cyanide ligands, deviate only by ten degrees from the molecular C 3 ‐axis. The exchange coupling in [(baron Me ){Fe III (CN) 2 } 3 ] 3– is ferromagnetic with J = 2.2 cm –1 but antiferromagnetic in [(baron Me ){Cr III (CN) 2 } 3 ] 3– with J = –1.76 cm –1 . The ferromagnetic coupling in the Fe III low‐spin complex is rationalized by a good π overlap of the d yz magnetic orbital with the O(p z ) orbitals of the central phloroglucinol unit. The three unpaired electrons of the Cr III ions in [(baron Me ){Cr III (CN) 2 } 3 ] 3– provide competing spin‐delocalization and spin‐polarization pathways, which explains the overall antiferromagnetic coupling. These two complexes are the first l.s. Fe III and Cr III complexes of triplesalen‐like ligands and emphasize the strong impact of the specific electronic configuration on the spin‐polarization mechanism via the central phloroglucinol. The potential of [(baron Me ){Fe III (CN) 2 } 3 ] 3– and [(baron Me ){Cr III (CN) 2 } 3 ] 3– as molecular building blocks for nonanuclear complexes by coordination to the six cyanides is discussed.