Abstract
Mononuclear heteroleptic complexes [Fe(tpma)(bimz)](ClO4)2 (1a), [Fe(tpma)(bimz)](BF4)2 (1b), [Fe(bpte)(bimz)](ClO4)2 (2a), and [Fe(bpte)(bimz)](BF4)2 (2b) (tpma = tris(2-pyridylmethyl)amine, bpte = S,S′-bis(2-pyridylmethyl)-1,2-thioethane, bimz = 2,2′-biimidazoline) were prepared by reacting the corresponding Fe(II) salts with stoichiometric amounts of the ligands. All complexes exhibit temperature-induced spin crossover (SCO), but the SCO temperature is substantially lower for complexes 1a and 1b as compared to 2a and 2b, indicating the stronger ligand field afforded by the N2S2-coordinating bpte ligand relative to the N4-coordinating tpma. Our findings suggest that ligands with mixed N/S coordination can be employed to discover new SCO complexes and to tune the transition temperature of known SCO compounds by substituting for purely N-coordinating ligands.
Highlights
The design of coordination environments for achieving reversible spin-state switching in transition metal complexes is an interesting endeavor that crosses the boundaries between inorganic, organic, and physical chemistry
One thinks of thioethers as rather weak ligands, and initially we were quite surprised by the observation of spin crossover (SCO) in such coordination environment
Complexes 1a, 1b, 2a, and 2b were synthesized by reacting Fe(II) perchlorate or tetrafluoroborate salts first with the bidentate ligand and with the tetradentate ligand in a MeOH-EtOH solvent mixture
Summary
The design of coordination environments for achieving reversible spin-state switching (spin crossover, SCO) in transition metal complexes is an interesting endeavor that crosses the boundaries between inorganic, organic, and physical chemistry. The majority of the SCO Fe(II) complexes feature the metal ion in the {N6 } coordination environment [2]. In order to expand the possibilities in the design of SCO complexes, it is important to find alternative coordination environments that can provide the appropriate ligand field strength for the occurrence of SCO. Our and other groups have reported SCO in several Fe(II) complexes with the {N4 S2 } coordination, in which the S-donor atoms are provided by thioether functionalities [3,4,5,6,7,8,9,10,11]. One thinks of thioethers as rather weak ligands, and initially we were quite surprised by the observation of SCO in such coordination environment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
