TY - JOUR
T1 - Structural and Spectroscopic Evidence for a Side-on Fe(III)-Superoxo Complex Featuring Discrete O-O Bond Distances
AU - Pan, Hung Ruei
AU - Chen, Hsin Jou
AU - Wu, Zong Han
AU - Ge, Pu
AU - Ye, Shengfa
AU - Lee, Gene Hsiang
AU - Hsu, Hua Fen
N1 - Funding Information:
We thank Ms. Shu-Yi Sun, Mr. Tsung-Lun Kan, and Mr. Bo-Rong Su at Instrument Center of National Cheng Kung University for assisting the measurements of elemental analysis, NMR, and ESI-MS, respectively. We thank the Ministry of Science and Technology in Taiwan for financial support (MOST 109-2113-M-006-007). H.-R.P. gratefully acknowledges the Ph.D. fellowship from Science College of National Cheng Kung University and Ministry of Science and Technology in Taiwan. S.Y. gratefully acknowledges the financial support from the Max-Planck Society, in particular, the joint work space of MPI-CEC and MPI-KOFO. G.P. gratefully acknowledges the financial support from the National Natural Science Foundation of China (No. 22006008).
Funding Information:
We thank Ms. Shu-Yi Sun, Mr. Tsung-Lun Kan and Mr. Bo-Rong Su at Instrument Center of National Cheng Kung University for assisting the measurements of elemental analysis, NMR, and ESI-MS respectively. We thank the Ministry of Science and Technology in Taiwan for financial support (MOST 109-2113-M-006-007). H.-R.P. gratefully acknowledges the Ph.D. fellowship from Science College of National Cheng Kung University and Ministry of Science and Technology in Taiwan. S.Y. gratefully acknowledges the financial support from the Max-Planck Society, in particular, the joint work space of MPI-CEC and MPI-KOFO. G.P. gratefully acknowledges the financial support from the National Natural Science Foundation of China (No. 22006008).
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2021/9/27
Y1 - 2021/9/27
N2 - The O-O bond length is often used as a structural indicator to determine the valence states of bound O2 ligands in biological metal-dioxygen intermediates and related biomimetic complexes. Here, we report very distinct O-O bond lengths found for three crystallographic forms (1.229(4), 1.330(4), 1.387(2) Å at 100 K) of a side-on iron-dioxygen species. Despite their different O-O bond distances, all forms possess the same electronic structure of Fe(III)-O2•-, as evidenced by their indistinguishable spectroscopic features. Density functional theory and ab initio calculations, which successfully reproduce spectroscopic parameters, predict a flat potential energy surface of an η2-O2 motif binding to the iron center regarding the O-O distance. Therefore, the discrete O-O bond lengths observed likely arise from differential intermolecular interactions in the second coordination sphere. The work suggests that the O-O distance is not a reliable benchmark to unequivocally identify the valence state of O2 ligands for metal-dioxygen species in O2-utilizing metalloproteins and synthetic complexes.
AB - The O-O bond length is often used as a structural indicator to determine the valence states of bound O2 ligands in biological metal-dioxygen intermediates and related biomimetic complexes. Here, we report very distinct O-O bond lengths found for three crystallographic forms (1.229(4), 1.330(4), 1.387(2) Å at 100 K) of a side-on iron-dioxygen species. Despite their different O-O bond distances, all forms possess the same electronic structure of Fe(III)-O2•-, as evidenced by their indistinguishable spectroscopic features. Density functional theory and ab initio calculations, which successfully reproduce spectroscopic parameters, predict a flat potential energy surface of an η2-O2 motif binding to the iron center regarding the O-O distance. Therefore, the discrete O-O bond lengths observed likely arise from differential intermolecular interactions in the second coordination sphere. The work suggests that the O-O distance is not a reliable benchmark to unequivocally identify the valence state of O2 ligands for metal-dioxygen species in O2-utilizing metalloproteins and synthetic complexes.
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U2 - 10.1021/jacsau.1c00184
DO - 10.1021/jacsau.1c00184
M3 - Article
AN - SCOPUS:85120355052
SN - 2691-3704
VL - 1
SP - 1389
EP - 1398
JO - JACS Au
JF - JACS Au
IS - 9
ER -