TY - JOUR
T1 - Preparation, structure, and dynamic and electrochemical behaviors of dinuclear rhodium(I) complexes with bridging formamidinato ligands
AU - Ide, Yuki
AU - Ikeue, Takahisa
AU - Kataoka, Yusuke
AU - Inoue, Ryoko
AU - Nakamura, Mikio
AU - Yoshioka, Daisuke
AU - Mikuriya, Masahiro
AU - Kawamoto, Tatsuya
AU - Handa, Makoto
N1 - Funding Information:
The present work was partially supported by Grants-in-Aid for Scientific Research Nos. and 26410080 from the Ministry of Education, Culture, Sports, Science and Technology and Technology and the Support Project to Assist Private Universities in Developing Bases for Research. The X-ray diffraction experiment was performed at Advanced Research Support Center, Ehime University. The authors are grateful to Dr. Mori (Ehime University) for the crystallographic analysis. The authors are grateful to Ms. Michiko Egawa (Shimane University) for her measurements of elemental analysis.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Dinuclear rhodium(I) complexes, [Rh(4-Me-pf) (cod)]2 (1), [Rh(3,5-Me2-pf) (cod)]2 (2), [Rh(4-Me-pf) (nbd)]2 (3), [Rh(3,5-Me2-pf) (nbd)]2 (4), and [Rh(2,6-F2-pf) (nbd)]2 (5), have been synthesized and characterized by X-ray structure analysis, 1H, 13C, and 19F NMR, UV-vis, ESI-TOF-MS, and elemental analysis. In these complexes, two rhodium atoms are bridged by two formamidinato ligands and each rhodium atom is coordinated by one chelating cod or nbd ligand to form an approximately square planar coordination structure with two nitrogen atoms and two double bonds. The Rh··Rh distances are in the range of 3.2668 to 2.9726 Å, suggesting a direct bonding interaction between two rhodium atoms. Variable temperature NMR studies in CD2Cl2 solution have revealed that 1-5 exhibit a novel dynamic behavior, that is, an interconversion between two enantiomers. The activation parameters for racemization have been determined by the line shape analyses of the 1H and 19F NMR spectra taken at various temperatures. Variable temperature NMR studies have also revealed that the rotation rates of the four aryl groups around N-C(aryl) bonds are extremely different in each complex. The cyclic voltammetry study has shown that the oxidation potentials corresponding to Rh23+/Rh2+ are 0.41 V in the cod complexes (1 and 2) while those in the nbd complexes (3-5) have shown negative shift by ca. 0.2 V. The reasons for the difference in dynamic behaviors and redox properties among these complexes have been discussed.
AB - Dinuclear rhodium(I) complexes, [Rh(4-Me-pf) (cod)]2 (1), [Rh(3,5-Me2-pf) (cod)]2 (2), [Rh(4-Me-pf) (nbd)]2 (3), [Rh(3,5-Me2-pf) (nbd)]2 (4), and [Rh(2,6-F2-pf) (nbd)]2 (5), have been synthesized and characterized by X-ray structure analysis, 1H, 13C, and 19F NMR, UV-vis, ESI-TOF-MS, and elemental analysis. In these complexes, two rhodium atoms are bridged by two formamidinato ligands and each rhodium atom is coordinated by one chelating cod or nbd ligand to form an approximately square planar coordination structure with two nitrogen atoms and two double bonds. The Rh··Rh distances are in the range of 3.2668 to 2.9726 Å, suggesting a direct bonding interaction between two rhodium atoms. Variable temperature NMR studies in CD2Cl2 solution have revealed that 1-5 exhibit a novel dynamic behavior, that is, an interconversion between two enantiomers. The activation parameters for racemization have been determined by the line shape analyses of the 1H and 19F NMR spectra taken at various temperatures. Variable temperature NMR studies have also revealed that the rotation rates of the four aryl groups around N-C(aryl) bonds are extremely different in each complex. The cyclic voltammetry study has shown that the oxidation potentials corresponding to Rh23+/Rh2+ are 0.41 V in the cod complexes (1 and 2) while those in the nbd complexes (3-5) have shown negative shift by ca. 0.2 V. The reasons for the difference in dynamic behaviors and redox properties among these complexes have been discussed.
KW - Crystal structures
KW - Cyclic voltammogram
KW - Dirhodium(I) complexes
KW - Dynamic NMR
KW - Formamidinato ligand
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U2 - 10.1016/j.jorganchem.2015.12.018
DO - 10.1016/j.jorganchem.2015.12.018
M3 - Article
AN - SCOPUS:84952701173
SN - 0022-328X
VL - 803
SP - 92
EP - 103
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
ER -