title: Isomeric ruthenium terpyridine complexes [Ru(trpy)(L)Cl]n+ containing the unsymmetrically bidentate acceptor L=3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine. Synthesis, structures, electrochemistry, spectroscopy and DFT calculations.
abstract: The isomeric title complexes were obtained in almost equimolar ratio from the reaction of Ru(trpy)Cl3 and L. Crystal structure analyses of the perchlorate hemihydrates, electrochemical and spectroscopic (NMR, UV/VIS, EPR) studies, supported by DFT calculations, reveal distinct differences between the isomeric redox series [1]n+(tetrazine-Nt trans to Cl) and [2]n+(pyrazolyl-Np trans to Cl; n= 0, 1, 2). The latter system with the pi acceptors trpy and tetrazine in the equatorial plane and the pyrazolyl and chloride donors in the axial positions exhibits facilitated oxidation, lower energy MLCT transitions, more balanced chelate coordination, and a higher g anisotropy in the oxidised (RuIII) state. According to partially resolved EPR spectra of one-electron reduced neutral compounds and they have the unpaired electron predominantly in the tetrazine ring of L.
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai, 400076, India.
authors.forename: Srikanta
authors.initials: S
authors.lastname: Patra
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar
authors.forename: Sandeep
authors.initials: S
authors.lastname: Ghumaan
authors.forename: Mahendra P
authors.initials: MP
authors.lastname: Patil
authors.forename: Shaikh M
authors.initials: SM
authors.lastname: Mobin
authors.forename: Raghavan B
authors.initials: RB
authors.lastname: Sunoj
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
authors.forename: Goutam Kumar
authors.initials: GK
authors.lastname: Lahiri