title: The intricate paramagnetic state of [Os(Q)2(bpy)]+, Q = 4,6-di-tert-butyl-o-iminobenzoquinone.
abstract: The combination of two highly non-innocent ligands with a third-row transition metal produces the title complex ion which was crystallised as [Os(Q)(2)(bpy)](ClO(4))·C(6)H(6) (Q = 4,6-di-tert-butyl-o-iminobenzoquinones, bpy = 2,2'-bipyridine) and could be structurally characterised to exhibit a tris-chelate situation at the metal with trans-positioned N and cis-positioned O donor atoms. The metrical ligand parameters are in agreement with two partially reduced ligands. A 3-spin interaction (Q˙(-))Os(III)(Q˙(-)) can rationalise the observed S = 1/2 situation with ligand-centred resulting spin. Ligand-based spin is confirmed by DFT (calculated spin populations Q: 1.113; Os: -0.113; bpy: 0.001) and is also apparent from the EPR signal (g(1) 1.981, g(2) 1.955, g(3) 1.803, Δg 0.178, <g> 1.915) which is influenced by the high spin-orbit coupling constant of the osmium centre. The susceptibility measurements reveal antiferromagnetic behaviour. A one-electron oxidation and two one-electron reductions could be monitored spectroelectrochemically (UV-VIS-NIR) and analysed by TD-DFT, in comparison with the results from the ruthenium analogue. The analysis reflects the strong orbital mixing between the metal and the two Q-ligand MOs.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
authors.forename: Dipanwita
authors.initials: D
authors.lastname: Das
authors.forename: Thomas Michael
authors.initials: TM
authors.lastname: Scherer
authors.forename: Amit
authors.initials: A
authors.lastname: Das
authors.forename: Tapan Kumar
authors.initials: TK
authors.lastname: Mondal
authors.forename: Shaikh M
authors.initials: SM
authors.lastname: Mobin
authors.forename: Jan
authors.initials: J
authors.lastname: Fiedler
authors.forename: José Luis
authors.initials: JL
authors.lastname: Priego
authors.forename: Reyes
authors.initials: R
authors.lastname: Jiménez-Aparicio
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
authors.forename: Goutam Kumar
authors.initials: GK
authors.lastname: Lahiri