Reactions of Dimesityldioxoosmium(VI) with Bidentate N -Heterocycles. Crystal Structure of a Dioxoosmium(VI) Complex Containing a Molecular Square
1996; American Chemical Society; Volume: 15; Issue: 5 Linguagem: Inglês
10.1021/om950531+
ISSN1520-6041
AutoresWa‐Hung Leung, J. Cheng, Tom S. M. Hun, Chi‐Ming Che, Wing‐Tak Wong, Kung-Kai Cheung,
Tópico(s)Magnetism in coordination complexes
ResumoThe interaction of OsO2(mes)2 (mes = mesityl) with pyz (pyrazine) gave the pyrazine-bridged dimer [OsO2(mes)2]2(μ-pyz) (1), which has been characterized by X-ray crystallography. The structure around Os in 1 is square pyramidal, with the pyrazine, two oxo ligands, and one mesityl group in the square plane. The Os−O distance and O−Os−O angle are 1.71 Å and 147.5°, respectively. The reaction of OsO2(mes)2 with 4,4‘-bpy (4,4‘-bipyridyl) and bpe (trans-1,2-bis(4-pyridyl)ethylene) in Et2O gave the oligomeric [OsO2(mes)2L]n (L = 4,4‘-bpy (2), bpe (3)) in good yields. The 1H NMR spectra of 2 and 3 indicate that L's are coordinated in a symmetric fashion in these oligomers. The reaction of OsO2(mes)2 with 4,4‘-bpy in CHCl3 followed by slow evaporation afforded the crystalline tetramer [OsO2(mes)2(μ-4,4‘-bpy)]4 (4). The crystal structure of the tetramer 4 contains the square-planar [Os(4,4‘-bpy)]4 core with octahedral local geometry around each Os. The Os−O distance and O−Os−O angle are 1.6 Å and 159°, respectively. Treatment of OsO2(mes)2 with CNpy (4-cyanopyridine) gave [OsO2(mes)2]·[OsO2(mes)2(CNpy)] (5). The structure of 5 consists of the four-coordinate [OsO2(mes)2] and five-coordinate [OsO2(mes)2(CNpy)] moieties, which are linked together via the OsO···Os interaction. The Os−O distances in the [OsO2(mes)2] and [OsO2(mes)2(CNpy)] moieties in 5 are 1.69 and 1.71 Å, respectively. The (Os)O···Os distance is 2.78 Å, and the Os−O···Os angle is 170°. The Os−O stretching frequency for the above dimesityldioxoosmium(VI) complexes correlates well with the Os−O bond order and the coordination environment around Os.
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