AUTHOR=Fleming Connor , Vu Son , Brook David J. R. , Agrestini Stefano , Pellegrin Eric , DaRos Jeffrey 

TITLE=Metal-ligand interactions in a redox active ligand system. Electrochemistry and spectroscopy of [M(dipyvd)2]n+ (M=Zn, Ni, n=0, 1, 2)

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1295289

DOI=10.3389/fchem.2023.1295289

ISSN=2296-2646

ABSTRACT=Reaction of nickel and zinc triflates with the tridentate leucoverdazyl 1-isopropyl-3,5-di(2′-pyridyl)-6-oxo-2H-tetrazine (dipyvdH) and triethylamine resulted in the neutral coordination compounds M(dipyvd)2 (M=Ni,Zn). In acetonitrile, both compounds undergo two one electron oxidation processes, Zn(dipyvd)2 at -0.28V and -0.12V and Ni(dipyvd)2 at -0.32V and -0.15V vs. ferrocene/ferricenium. Oxidations are ligand based resulting in an intermediate mixed valence species and a cationic bis(verdazyl) compound respectively. Oxidation of the ligand changes a localized, antiaromatic, non-planar 8π electron anion to a planar, delocalized 7π electron radical. The change in ligand structure results in an increase in the octahedral ligand field splitting from 10500 cm -1 to ~13000 cm -1 , suggesting an increase in the pi acceptor character of the ligand. In the mixed valence species, spectroscopic data suggests minimal interaction between ligands mediated by the metal center; i.e. these are class I-II systems in the Robin-Day classification.