Synthesis and Characterisation of Luminescent [CrIII2L(μ-carboxylato)]3+ Complexes with High-Spin S=3 Ground States (L=N6S2 donor ligand)

Börner ,M.; Klose, J.; Gutierrez Suburu, M. E.; Strassert, C. A.; Yang, F.; Monakhov, K. Y.; Abel, B.; Kersting, B.

Research article (journal)

Abstract

Abstract The synthesis, structure, magnetic, and photophysical properties of two dinuclear, luminescent, mixed-ligand [CrIII2L(O2CR)]3+ complexes (R=CH3 (1), Ph (2)) of a 24-membered binucleating hexa-aza-dithiophenolate macrocycle (L)2? are presented. X-ray crystallographic analysis reveals an edge-sharing bioctahedral N3Cr(?-SR)2(?1,3-O2CR)CrN3 core structure with ?1,3-bridging carboxylate groups. A ferromagnetic superexchange interaction between the electron spins of the Cr3+ ions leads to a high-spin (S=3) ground state. The coupling constants (J=+24.2(1)?cm?1 (1), +34.8(4)?cm?1 (2), H=?2JS1S2) are significantly larger than in related bis-?-alkoxido-?-carboxylato structures. DFT calculations performed on both complexes reproduce both the sign and strength of the exchange interactions found experimentally. Frozen methanol-dichloromethane 1?:?1 solutions of 1 and 2 luminesce at 750?nm when excited into the 4LMCT state on the 4A2 ? 2T1 (?2) bands (?exc=405?nm). The absolute quantum yields (ΦL) for 1 and 2 were found to be strongly temperature dependent. At 77?K in frozen MeOH/CH2Cl2 glasses, ΦL=0.44±0.02? (for 1), ΦL=0.45±0.02? (for 2).

Details zur Publikation

Publisher:
Release year: 2021
Publishing company: John Wiley & Sons, Ltd
Language in which the publication is written: English
Link to the full text: https://doi.org/10.1002/chem.202102079