Role of coordination geometry on the magnetic relaxation dynamics of isomeric five-coordinate low-spin Co(II) complexes

• Verfasst von: Spillecke, Lena [VerfasserIn]
• Verfasst von: Tripathi, Shalini [VerfasserIn]
• Verfasst von: Koo, Changhyun [VerfasserIn]
• Verfasst von: Bahr, Arne [VerfasserIn]
• Verfasst von: Swain, Abinash [VerfasserIn]
• Verfasst von: Haldar, Rajashi [VerfasserIn]
• Verfasst von: Ansari, Mursaleem [VerfasserIn]
• Verfasst von: Jasinski, Jerry [VerfasserIn]
• Verfasst von: Rajaraman, Gopalan [VerfasserIn]
• Verfasst von: Shanmugam, Maheswaran [VerfasserIn]
• Verfasst von: Klingeler, Rüdiger [VerfasserIn]
• Titel: Role of coordination geometry on the magnetic relaxation dynamics of isomeric five-coordinate low-spin Co(II) complexes
• Verf.angabe: Lena Spillecke, Shalini Tripathi, Changhyun Koo, Arne Bahr, Abinash Swain, Rajashi Haldar, Mursaleem Ansari, Jerry Jasinski, Gopalan Rajaraman, Maheswaran Shanmugam, and Rüdiger Klingeler
• Jahr: 2022
• Umfang: 11 S.
• Fussnoten: Published: December 17, 2021 ; Gesehen am 18.07.2022
• Titel Quelle: Enthalten in: Inorganic chemistry
• Ort Quelle: Washington, DC : American Chemical Society, 1962
• Jahr Quelle: 2022
• Band/Heft Quelle: 61(2022), 1, Seite 317-327
• ISSN Quelle: 1520-510X
• DOI: doi:10.1021/acs.inorgchem.1c02881
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1810702771

Abstract

To investigate the influence of the coordination geometry on the magnetization relaxation dynamics, two geometric isomers of a five-coordinate low-spin Co(II) complex with the general molecular formula [Co(DPPE)2Cl]SnCl3 (DPPE = diphenylphosphinoethane) were synthesized and structurally characterized. While one isomer has a square pyramidal geometry (Co-SP (1)), the other isomer figures a trigonal bipyramidal geometry (Co-TBP (2)). Both complexes were already reported elsewhere. The spin state of these complexes is unambiguously determined by detailed direct current (dc) magnetic data, X-band, and high-frequency EPR measurements. Slow relaxation of magnetization is commonly observed for systems with S > 1/2. However, both 1 and 2 show field-induced slow relaxation of magnetization. Especially 1 shows relaxation times up to τ = 35 ms at T = 1.8 K, which is much longer than the reported values for undiluted Co(II) low-spin monomers. In 2, the maximal field-induced relaxation time is suppressed to τ = 5 ms. We attribute this to the change in g-anisotropy, which is, in turn, correlated to the spatial arrangement of ligands (i.e., coordination geometry) around the Co(II) ions. Besides the detailed electronic structure of these complexes, the experimental observations are further corroborated by theoretical calculations.