• Costuas, K.
• Low, Paul J.
• Skelton, Brian
• Smith, M. E.
• Davin, T.
• Kramarczuk, K. A.
• Bruce, M. I.
• Halet, J-F.
• Nicholson, B. K.
• Roberts, R. L.
• White, Allan
• Perkins, G. J.

Abstract

The sequential conversion of [OsBr(cod)Cp*] (9) to [OsBr(dppe)Cp*] (10), [Os(=C=CH2)(dppe)Cp*] PF6 ([11]PF6), [Os(C 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 CC C)] (14) has been used to make the third member of the triad [{M(dppe)Cp*}(2)(mu-C CC C)] (M = Fe, Ru, Os). The molecular structures of [11]PF6, 12 and 14, together with those of the related osmium complexes [Os(NCMe)(dppe)Cp*]PF6 ([15]PF6) and [Os(C 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 E-1 varies as: Fe approximate to 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-C-4)](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.

Topics

• compound
• x-ray diffraction
• density functional theory
• iron
• molecular structure
• Osmium
• Ruthenium