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Issue 14, 1992
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Co-ordination chemistry of higher oxidation states. Part 40. Spectroscopic, electrochemical and structural studies of cationic osmium-(III) and -(IV) diphosphine and diarsine complexes

Abstract

The osmium(III) complexes trans-[Os(L–L)2X2]BF4[X = Cl or Br; L–L =o-C6H4(PMe2)2, o-C6H4(AsMe2)2, o-C6H4(AsMe2)(PMe2), o-C6F4(AsMe2)2, Ph2PCH2CH2PPh2, Me2PCH2CH2PMe2, Ph2AsCH[double bond, length half m-dash]CHAsPh2, o-C6H4(PPh2)2 or o-C6F4(PPh2)2] have been prepared by dilute HNO3 oxidation of the osmium(II) analogues in aqueous HBF4. Concentrated HNO3 converts most of these complexes into OsIV, but the unstable trans-[Os(L–L)2X2][ClO4]2 were isolated as solids only for L–L =o-C6H4(PMe2)2, o-C6H4(AsMe2)2 or o-C6H4(AsMe2)(PMe2). Cyclic voltammetry reveals that the OsII–OsIII and OsIII–OsIV couples are generally reversible. Assignments of the UV/VIS spectra of the osmium-(III) and -(IV) complexes are proposed. The X-ray structure of trans-[Os{o-C6H4(AsMe2)2}2Cl2]ClO4 is reported: monoclinic, space group C2/m, a= 13.890(2), b= 10.381(2), c= 11.682(3)Å, β= 113.86(2)°, Z= 2, and with R= 0.039. Osmium LIII-edge (and where appropriate bromine K-edge) extended X-ray absorption fine structure data for the complexes trans-[Os{o-C6H4(AsMe2)2}2X2]n+(n= 0–2) are reported and the trends in Os–As and Os–X bond lengths with changing osmium oxidation state are discussed.

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Article information


J. Chem. Soc., Dalton Trans., 1992, 2201-2207
Article type
Paper

Co-ordination chemistry of higher oxidation states. Part 40. Spectroscopic, electrochemical and structural studies of cationic osmium-(III) and -(IV) diphosphine and diarsine complexes

N. R. Champness, W. Levason, D. Pletcher, M. D. Spicer and M. Webster, J. Chem. Soc., Dalton Trans., 1992, 2201
DOI: 10.1039/DT9920002201

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