Yergeshbayeva Sandugash, Hrudka Jeremy J, Jo Minyoung, Gakiya-Teruya Miguel, Meisel Mark W, Shatruk Michael
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States.
Department of Physics, University of Florida, Gainesville, Florida 32611-8440, United States.
Inorg Chem. 2022 Jul 25;61(29):11349-11358. doi: 10.1021/acs.inorgchem.2c01490. Epub 2022 Jul 11.
A heteroleptic spin-crossover (SCO) complex, Fe(tpma)(xnap-bim) (; tpma = tris(2-pyridylmethyl)amine, xnap-bim = 8,15-dihydrodiimidazo[1,2-:2',1'-]naphtho[2,3-][1,4]diazocine), has been obtained by reacting a Fe(II) precursor salt with tetradentate tpma and bidentate xnap-bim ligands. Depending on crystallization conditions, two different solvates have been obtained, ·2.25py·0.5HO and ·py. The former readily loses the interstitial solvent to produce either a powder sample of upon filtration or crystals of if the solvent loss is slowed by placing the crystals of ·2.25py·0.5HO in diethyl ether. In contrast, ·py exhibits higher stability toward solvent loss. The crystal packing of both solvates and of the solvent-free structure features double columns of [Fe(tpma)(xnap-bim)] cations formed by efficient π-π interactions between the pyridyl groups of tpma ligands, as well as by stacks supported by π-π interactions between interdigitated naphthalene fragments of xnap-bim ligands. While both solvates show a gradual SCO between the high-spin (HS) and low-spin (LS) states of the Fe(II) ion, solvent-free complex exhibits an abrupt spin transition centered at 127 K, with a narrow 2 K thermal hysteresis. Complex also shows a light-induced excited spin state trapping effect, manifested as LS → HS conversion upon irradiation with white light at 5 K. The metastable HS state relaxes to the ground LS state when heated above 65 K.
通过使二价铁前驱体盐与四齿配体三（2 - 吡啶甲基）胺（tpma）和双齿配体8,15 - 二氢二咪唑并[1,2 - :2',1'-]萘并[2,3 - ][1,4]二氮杂辛（xnap - bim）反应，得到了一种杂配体自旋交叉（SCO）配合物Fe(tpma)(xnap - bim)。根据结晶条件，得到了两种不同的溶剂化物，·2.25py·0.5HO和·py。前者容易失去间隙溶剂，过滤后得到粉末状样品，如果将·2.25py·0.5HO晶体置于乙醚中减缓溶剂损失，则可得到晶体。相比之下，·py对溶剂损失表现出更高的稳定性。两种溶剂化物以及无溶剂结构的晶体堆积都具有由tpma配体吡啶基团之间有效的π - π相互作用形成的[Fe(tpma)(xnap - bim)]阳离子双柱，以及由xnap - bim配体相互交错的萘片段之间的π - π相互作用支撑的堆积。虽然两种溶剂化物在Fe(II)离子的高自旋（HS）和低自旋（LS）状态之间都显示出逐渐的自旋交叉，但无溶剂配合物在127 K处呈现出以2 K窄热滞回为中心的突然自旋转变。配合物还表现出光诱导激发自旋态捕获效应，在5 K下用白光照射时表现为LS→HS转换。当加热到65 K以上时，亚稳态HS态弛豫到基态LS态。
