Ahmed Manan, Arachchige Kasun S A, Xie Zixi, Price Jason R, Cruddas Jace, Clegg Jack K, Powell Benjamin J, Kepert Cameron J, Neville Suzanne M
School of Chemistry, The University of New South Wales, Sydney 2052, Australia.
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia.
Inorg Chem. 2022 Aug 1;61(30):11667-11674. doi: 10.1021/acs.inorgchem.2c01253. Epub 2022 Jul 21.
A detailed study of the two-dimensional (2-D) Hofmann-like framework [Fe(furpy)Pd(CN)]·G (furpy: -(pyridin-4-yl)furan-2-carboxamide, G = HO,EtOH (·HO,Et), and HO (·HO)) is presented, including the structural and spin-crossover (SCO) implications of subtle guest modification. This 2-D framework is characterized by undulating Hofmann layers and an array of interlayer spacing environments─this is a strategic approach that we achieve by the inclusion of a ligand with multiple host-host and host-guest interaction sites. Variable-temperature magnetic susceptibility studies reveal an asymmetric multistep SCO for ·HO,Et and an abrupt single-step SCO for ·HO with an upshift in transition temperature of ∼75 K. Single-crystal analyses show a primitive orthorhombic symmetry for ·HO,Et characterized by a unique Fe center─the multistep SCO character is attributed to local ligand orientation. Counterintuitively, ·HO shows a triclinic symmetry with two inequivalent Fe centers that undergo a cooperative single-step high-spin (HS)-to-low-spin (LS) transition. We conduct detailed structure-function analyses to understand how the guest ethanol influences the delicate balance between framework communication and, therefore, the local structure and spin-state transition mechanism.
本文对二维（2-D）类霍夫曼骨架[Fe(furpy)Pd(CN)]·G（furpy：-(吡啶-4-基)呋喃-2-甲酰胺，G = HO，EtOH（·HO，Et），以及HO（·HO））进行了详细研究，包括客体细微修饰对结构和自旋交叉（SCO）的影响。这种二维骨架的特征在于起伏的霍夫曼层和一系列层间距环境——这是我们通过引入具有多个主体-主体和主体-客体相互作用位点的配体实现的一种策略性方法。变温磁化率研究表明，·HO，Et呈现不对称多步SCO，而·HO呈现 abrupt 单步SCO，转变温度上移约75 K。单晶分析表明，·HO，Et具有原始正交对称性，其特征在于独特的铁中心——多步SCO特性归因于局部配体取向。与直觉相反，·HO呈现三斜对称性，有两个不等价的铁中心，它们经历协同单步高自旋（HS）到低自旋（LS）转变。我们进行了详细的结构-功能分析，以了解客体乙醇如何影响骨架通信之间的微妙平衡，进而影响局部结构和自旋态转变机制。
