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Formazanate Complexes of Bis-Cyclometalated Iridium

preprint
submitted on 03.06.2019 and posted on 04.06.2019 by Evanta Kabir, Ge Mu, David A. Momtaz, Noah A. Bryce, Thomas Teets
In this work we describe a series of bis-cyclometalated iridium(III) formazanate complexes, expanding the coordination chemistry of the redox-active formazanate class to iridium. A total of 18 new complexes are described, varying the substituent pattern on the formazanate and the identity of the cyclometalating ligand on iridium. Eight of the new compounds are structurally characterized by single-crystal X-ray diffraction, which along with NMR spectroscopy evinces two binding modes of the formazanate. Two of the compounds are isolated in a C2-symmetric geometry where the formazanate is bound in a six-member chelate “closed” conformation, involving the 1- and 5-positions of the 1,2,4,5-tetraazapentadienyl formazanate core. In most of the examples, the major isomer that forms and is exclusively isolated involves the formazanate bound in a five-member chelate “open” form, coordinating through the 1- and 4-positions of the formazanate core and resulting in C1 point-group symmetry. All complexes are characterized by UV-vis absorption spectroscopy and cyclic voltammetry, with these features depending primarily on the substitution pattern on the formazanate, and to a lesser extent on the identity of the cyclometalating ligand and formazanate binding mode.

History

Email Address of Submitting Author

tteets@uh.edu

Institution

University of Houston

Country

United States

ORCID For Submitting Author

0000-0002-7471-8467

Declaration of Conflict of Interest

no conflict of interest

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