title: NH/pi interaction in a spin-crossover complex [FeII(HLMe)2](BPh4)2.2CH3CN (BPh4-=Tetraphenylborate; HLMe=2-Methylimidazol-4-yl-methylideneamino-2-ethylpyridine).
abstract: Three FeII complexes, [Fe(HLR)2](BPh4)2.solvent (R=H, Me, Ph), were synthesized, where BPh4-=tetraphenylborate and HLR=2-substituted-imidazol-4-yl-methylideneamino-2-ethylpyridine. The magnetic susceptibility measurements in 5-300 K revealed that [Fe(HLH)2](BPh4)2.H2O, [Fe(HLMe)2](BPh4)2.2CH3CN, and [Fe(HLPh)2](BPh4)2.CH3CN are low-spin (LS), spin-crossover (SC), and high-spin (HS) FeII complexes, respectively, indicating that the spin state can be effectively tuned by the bulkiness of the substituent. Complex shows a steep SC around 250 K, where it assumes a cyclic structure of {[Fe(HLMe)2]BPh4}2 constructed by four NH/pi bonds between the imidazole group and the phenyl ring of BPh4- in the HS state and a deformed structure with NH/pi bonds and linear CH3CN...HN hydrogen bonds at the terminals in the LS state.
authors.affiliation: Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Arata
authors.forename: Haruna
authors.initials: H
authors.lastname: Torigoe
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Iihoshi
authors.forename: Naohide
authors.initials: N
authors.lastname: Matsumoto
authors.forename: Françoise
authors.initials: F
authors.lastname: Dahan
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Tuchagues
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008280:Magnetics; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013696:Temperature; D013775:Tetraphenylborate / Q000737:chemistry*
chemical_list: C511820:2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine; D005296:Ferrous Compounds; D007093:Imidazoles; D009942:Organometallic Compounds; D011725:Pyridines; C511818:iron(II)(2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine)2(tetraphenylborate)2.2CH3CN; D013775:Tetraphenylborate; D007501:Iron