Chemistry of osmium in N2P2Br2 coordination sphere: synthesis, structure and reactivities

Das, Anindya ; Basuli, Falguni ; Peng, Shie-Ming ; Bhattacharya, Samaresh (1999) Chemistry of osmium in N2P2Br2 coordination sphere: synthesis, structure and reactivities Polyhedron, 18 (21). pp. 2729-2736. ISSN 0277-5387

Full text not available from this repository.

Official URL:

Related URL:


A family of three mixed-ligand osmium complexes of type [Os(PPh3)2(N-N)Br2], where N-N=2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (Me2bpy) and 1,10-phenanthroline (phen), have been synthesized and characterized. The complexes are diamagnetic (low-spin d6, S=0) and in dichloromethane solution they show intense MLCT transitions in the visible region. The two bromide ligands have been replaced from the coordination sphere of [Os(PPh3)2(phen)Br2] under mild conditions by a series of anionic ligands L (where L=quinolin-8-olate (q), picolinate (pic), oxalate (Hox) and 1-nitroso-2-naphtholate (nn)) to afford complexes of type [Os(PPh3)2(phen)(L)]+, which have been isolated and characterized as the perchlorate salt. The structure of the [Os(PPh3)2(phen)(pic)]ClO4 complex has been determined by X-ray crystallography. The PPh3 ligands occupy trans positions and the picolinate anion is coordinated to osmium as a bidentate N,O-donor forming a five-membered chelate ring. The [Os(PPh3)2(phen)(L)]+ complexes are diamagnetic and show multiple MLCT transitions in the visible region. The [Os(PPh3)2(N-N)Br2] complexes show an osmium(II)-osmium(III) oxidation (-0.02 to 0.12 V vs. SCE) followed by an osmium(III)-osmium(IV) oxidation (1.31 to 1.43 V vs. SCE). The [Os(PPh3)2(phen)(L)]+ complexes display the osmium (II)-osmium (III) oxidation (0.26 to 0.84 V vs. SCE) and one reduction of phen (-1.50 to -1.79 V vs. SCE). The osmium (III)-osmium (IV) oxidation has been observed only for the L=q and L=Hox complexes at 1.38 V vs. SCE and 1.42 V vs. SCE respectively. The osmium(III) species, viz. [OsIII(PPh3)2(N-N)Br2]+and [OsIII(PPh3)2(phen)(L)]2+, have been generated both chemically and electrochemically and characterized in solution by electronic spectroscopy and cyclic voltammetry.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Osmium; Triphenylphosphine; Diimine; Synthesis; Structure; Reactivities
ID Code:1934
Deposited On:08 Oct 2010 11:19
Last Modified:21 Jan 2011 11:24

Repository Staff Only: item control page