More about the redox behavior of late transition metal triple-decker complexes with cyclo-triphosphorus

The syntheses of the new triple-decker complexes [(triphos)Co(mu,etha3:3-P3)Ru(triphos)](BPh4)2; (CoP3Ru)(BPh4)2, [(triphos)Co(mu,etha·3:3-P3)Os(triphos)](BPh4)2; (CoP3Os)(BPh4)2 and [(triphos)Ru(mu,etha3:3-P3)Ru(triphos)]PF6·(CH3)2CO; (RuP3Ru)PF6·(CH3)2CO, three new members of the [(tripod)M(mu-P3)M'(tripod)]n+ (MP3M' n+ ) family are described. The structure of the homodinuclear complex (RuP3Ru)PF6·(CH3)2CO is also reported. This latter compound has a structure similar to that of the other members of the series and shows an M-M separation among the longest hitherto found in these compounds. An electrochemical study shows that they are stable in various oxidation states with a VEN value ranging between 28 and 34. A reasoning around the redox data shows a progressive shift of two pairs of redox processes, corresponding to the VEN variation 30/31-31/32 and 32/33-33/34, which almost rigidly moves in the cathode direction as the overall charge of the homoelectronic compound decreases.