Mononuclear and Binuclear Tetrapyrido[2,3-a:3‘,2‘-c:2‘‘,3‘‘-h:3‘‘‘,2‘‘‘-j]phenazine (tphz) Ruthenium Complexes

The mono- and binuclear ruthenium complexes [(tpy)Ru II (tphz)](PF 6 ) 2 ·3H 2 O ( 2 ) and [(tpy)Ru II (tphz)Ru II (tpy)](PF 6 ) 4 ·3H 2 O ( 3 ), where tphz ( 1 ) is the fully conjugated tetrapyrido[2,3-a:3‘,2‘-c:2‘‘,3‘‘-h:3‘‘‘,2‘‘‘-j]phenazine, have been prepared and characterized. The analysis of the intervalence band of the mixed-valence [(tpy)Ru II (tphz)Ru III (tpy)] 5+ showed that it belongs to the class II with an electron coupling parameter V ab of 0.05 eV, much smaller than for the analogous class III 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tpp) complex ( V ab = 0.4 eV). This discrepancy has been interpreted as a lack of adaptation of tphz to the chelation of the ruthenium atoms.