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( l , g 3:3 -P 3 )Ru(triphos)](BPh 4 ) 2 ; (CoP 3 Ru) (BPh 4 ) 2 , [(triphos)Co( l , g 3:3 -P 3 )Os(triphos)](BPh 4 ) 2 ; (CoP 3 Os)(BPh 4 ) 2 and [(triphos)Ru( l , g 3:3 -P 3 )Ru(tri-phos)]PF 6 (CH 3 ) 2 CO; (RuP 3 Ru)PF 6 (CH 3 ) 2 CO, three new members of the [(tripod)M( l -P 3 )M 0 (tripod)] n+(MP3M 0 n+ ) family are described. The structure of the homodinuclear complex (RuP 3 Ru)PF 6 (CH 3 ) 2 CO 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 electrochem- ical 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.