1,8-DIPHENYLOCTA-1,3,5,7-TETRAENE COMPLEXES OF RUTHENIUM(II) - CRYSTAL-STRUCTURES OF [MU-(S-CIS-1,2,3,4-ETA 8-ETA-PHCH=CHCH=CHCH=CHCH=CHPH)(RUCLCP-ASTERISK)2] AND ,8-ETA-PHCH=CHCH=CHCH=CHCH=CHPH)(RU(ACAC)(2))(2)]/

Reaction of 1,8-diphenyl-1,3,5,7-octatetraene with [Ru(mu Cl)Cp](4) ( 1) (Cp = eta(5)-pentamethylcyclopentadienyl) gave 5,6,7,8-eta-PhCH=CH CH-CHCH-CHCH-CHPh)(RuClCp)(2)] (2), whose crystal structure revealed that 2 has a planar tetraene backbone coordinated by two CpRuCl moiet ies in s-cis-eta(4)-fashion; while the reaction with Ru(acac)(3)/Zn sy stem resulted in the formation of 7,8-eta-PhCH=CHCH=CHCH=CHCH=CHPh){Ru (acac)(2)}(2)] (3), where both of the two Ru(acac)(2) moieties prefer s-trans coordination and thus the plane of the octatetraene backbone o f 3 is deformed into an S-shape. Electrochemical studies for complexes 2 and 3 revealed that they have a coupling between the two ruthenium centers and are conjugatively interacted d pi-p pi organometallic syst ems.