Abstract
(μ4-TCNX)Ru(NH3)54n+, TCNX = TCNE (tetracyanoethene), TCNQ (tetracyano-p-quinodimethane), TCNP (2,3,5,6-tetracyanopyrazine), and TCNB (1,2,4,5-tetracyanobenzene), were synthesized in the resp. (8+) states with PF6- (TCNE, TCNQ, TCNP) or CF3SO3- counterions (TCNB). IR, UV/visible/near-IR, and XPS spectroscopies were used to characterize the tetranuclear (8+) ions which exhibit four equiv. nitrile and pentaamminemetal groups and intense long-wavelength optical absorptions. The (8+) ions are easily oxidized to (10+) species and reduced stepwise to (7+) and (6+) ions; EPR, UV/visible/near-IR, and, in part, IR spectroelectrochem. techniques were applied to these oxidn. states in the case of the TCNE, TCNQ, and TCNB systems. The complexes may be described as fully delocalized sym. tetrametalla p systems (TCNXδ-)RuII+δ/4(NH3)54n+ with partially reduced ligands and fractionally oxidized metal centers. The extent of metal-to-ligand electron transfer in the ground state is higher for the TCNQ and TCNE complexes than for the tetranuclear TCNP and TCNB compds. on SciFinder(R)
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