Synthesis, structures, spectroscopic and electrochemical studies of Ru(II) complexes containing bis(phosphino)amine ligands.: Crystal and molecular structures of trans-[RuCl2{Ph2PN(Me)PPh2-κP,κP}2] and trans-[RuCl2{Ph2PN(iPr)PPh2-κP,κP}2]

The synthesis, characterization and X-ray crystal study of the monomeric neutral complexes of general formula trans[RuCl2{Ph2PN(R)PPh2-kappaP,kappaP}(2)] (R = H 1, Me 2, Et 3, Pr-n 4, Pr-i 5, Bu-n 6, Ph 7) is described. The analogous cis complexes, cis[RuCl2 {Ph2PN(R)PPh2-kappaP,kappaP}(2)] (R = H 8, Me 9), have also been synthesized and are characterized, The trans [RuCl2{Ph2PN(Me)PPh2-kappaP,kappaP}(2)] complex reacts with Ag2SO4 to give a cis neutral complex, [Ru (SO4)-kappaO,kappaO} {Ph2PN(Me)PPh2-kappaP,kappaP}(2)] (10) in good yield. Cyclic voltammograms of the complexes show two one-electron oxidation waves, one being quasi-reversible (Ru-III/ Ru-II) and the other chemically irreversible (Ru-IV/Ru-III) with E-1/2(Ru-III/Ru-II)(cis) > E-1/2(Ru-III/Ru-II)(trans). The more positive (Ru-III/ Ru-II) potential for the cis isomer compared to that of trans isomer is consistent with stabilization of the dpi levels in the cis compared to the trans complex. (C) 2003 Elsevier Science Ltd. All rights reserved.