title: Syntheses, structures and redox properties of some complexes containing the Os(dppe)Cp* fragment, including [{Os(dppe)Cp*}2(mu-C triple bondCC triple bond C)].
abstract: The sequential conversion of [OsBr(cod)Cp*] (9) to [OsBr(dppe)Cp*] (10), [Os([=C=CH2)(dppe)Cp*]PF6 ([11]PF6), [Os(C triple bond CH)(dppe)Cp*] (12), [{Os(dppe)Cp*}2{mu-(=C=CH-CH=C=)}][PF6]2 ([13](PF6)2) and finally [{Os(dppe)Cp*}(2)(mu-C triple bond CC triple bond C)] (14) has been used to make the third member of the triad [{M(dppe)Cp*}2(mu-C triple bond CC triple bond C)] (M = Fe, Ru, Os). The molecular structures of []PF6, 12 and 14, together with those of the related osmium complexes [Os(NCMe)(dppe)Cp*]PF6 ([15]PF6) and [Os(C triple bond CPh)(dppe)Cp*] (16), have been determined by single-crystal X-ray diffraction studies. Comparison of the redox properties of 14 with those of its iron and ruthenium congeners shows that the first oxidation potential E1 varies as: Fe approximately Os < Ru. Whereas the Fe complex has been shown to undergo three sequential 1-electron oxidation processes within conventional electrochemical solvent windows, the Ru and Os compounds undergo no fewer than four sequential oxidation events giving rise to a five-membered series of redox related complexes [{M(dppe)Cp*}2(mu-C4)]n+ (n = 0, 1, 2, 3 and 4), the osmium derivatives being obtained at considerably lower potentials than the ruthenium analogues. These results are complimented by DFT and DT DFT calculations.
authors.affiliation: School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Bruce
authors.forename: Karine
authors.initials: K
authors.lastname: Costuas
authors.forename: Thomas
authors.initials: T
authors.lastname: Davin
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Halet
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Kramarczuk
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Low
authors.forename: Brian K
authors.initials: BK
authors.lastname: Nicholson
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Perkins
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Roberts
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smith
authors.forename: Allan H
authors.initials: AH
authors.lastname: White