Responsive Four‐Coordinate Iron(II) Nodes in FePd(CN)<sub>4</sub>
Ryo Ohtani, Hiromu Matsunari, Takafumi Yamamoto, Koji Kimoto, M. Isobe, Kotaro Fujii, Masatomo Yashima, Susumu Fujii, Akihide Kuwabara, Yuh Hijikata, Shin‐ichiro Noro, Masaaki Ohba, Hiroshi Kageyama, Shinya Hayami
Abstract
Abstract Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal–organic frameworks with desirable properties; however, Fe II ions are exclusively six‐coordinated. Herein, we present a cyanide‐bridged three‐dimensional (3D) CP, FePd(CN) 4 , bearing four‐coordinate Fe II ions, which is synthesized by thermal treatment of a two‐dimensional (2D) six‐coordinate Fe II CP, Fe(H 2 O) 2 Pd(CN) 4 ⋅4 H 2 O, to remove water molecules. Atomic‐resolution transmission electron microscopy and powder X‐ray and neutron diffraction measurements revealed that the FePd(CN) 4 structure is composed of a two‐fold interpenetrated PtS topology network, where the Fe II center demonstrates an intermediate geometry between tetrahedral and square‐planar coordination. This four‐coordinate Fe II center with the distorted geometry can act as a thermo‐responsive flexible node in the PtS network.