title: Axial Mn-CCN Bonds of Cyano Manganese(II) Porphyrin Complexes: Flexible and Weak?
abstract: Three five-coordinate high-spin (cyano)manganese(II) complexes, utilized tetraphenylporphyrin (TPP), tetratolylporphyrin (TTP), and tetramesitylporphyrin (TMP) as ligands, are prepared and studied by single-crystal X-ray, FT-IR, UV-vis, and EPR spectroscopies. The crystal structure studies revealed noteworthy structural features including unexpectedly wide tilting angles of the axial Mn-CCN bonds, which is contrasted to the isoelectronic Fe(III)-CCN bonds. Solid-state EPR measurements (90 K) and simulations are applied to obtain the ZFS parameters (D, E, and E/D (λ)), which are compared to Mn(II) porphyrin analogues of hemes to understand the ligand field of the cyanide. The solution EPR studies gave new insights into the chemical equilibrium of four- and five-coordinate species, which has been monitored by UV-vis spectroscopy.
authors.affiliation: College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences , Yanqi Lake, Huairou District, Beijing 101408, China.
authors.forename: Mingrui
authors.initials: M
authors.lastname: He
authors.affiliation: College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences , Yanqi Lake, Huairou District, Beijing 101408, China.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Li
authors.affiliation: Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences , Yanqi Lake, Huairou District, Beijing 101408, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li