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Ruthenium Complexes Containing "Noninnocent" o-Benzoquinone Diimine/ o-Phenylenediamide(2-) Ligands. Synthesis and Crystal Structure of the Nitrido-Bridged Complex [{LRu(o-C 6H 4(NH) 2)} 2(μ-N)](PF 6) 2·3CH 3CN·C 6H 5CH 3

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  • Thomas Jüstel
  • Bendix, Jesper
  • Nils Metzler-Nolte
  • Thomas Weyhermüller
  • Bernhard Nuber
  • Karl Wieghardt

Reaction of LRu IIICl 3 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) with 1,2-phenylenediamine (opdaH 2) in H 2O in the presence of air affords [LRu II(bqdi)(OH 2)(PF 6) (1), where (bqdi) represents the neutral ligand o-benzoquinone diimine. From an alkaline methanol/water mixture of 1 was obtained the dinuclear species [{LRu II(bqdi)} 2(μ-H 3O 2)](PF 6) 3 (1a). The coordinated water molecule in 1 is labile and can be readily substituted under appropriate reaction conditions by acetonitrile, yielding [LRu II(bqdi)(CH 3CN)](PF 6) 2 (2), and by iodide and azide anions, affording [LRu II(bqdi)I](PF 6)·0.5H 2O (3) and [LRu(bqdi)(N 3)](PF 6)·H 2O (4), respectively. Heating of solid 4 in vacuum at 160 °C generates N 2 and the dinuclear, nitrido-bridged complex [{LRu(o-C 6H 4(NH) 2)} 2(μ-N)](PF 6) 2 (5). Complex 5 is a mixed-valent, paramagnetic species containing one unpaired electron per dinuclear unit whereas complexes 1-4 are diamagnetic. The crystal structures of 1, 1a·3CH 3CN, 3, 4·H 2O, and 5-3CH 3CN·0.5-(toluene) have been determined by X-ray crystallography: 1 crystallizes in the monoclinic space group P2 1/m, Z = 2, with a = 8.412(2) Å, b = 15.562(3) Å, c = 10.025 Å, and β = 109.89(2)°; 1a·3CH 3CN, in the monoclinic space group C2/c, Z = 4, with a = 19.858(3) Å, b = 15.483(2) Å, c = 18.192(3) Å, and β = 95.95(2)°; 3, in the orthorhombic space group Pnma, Z = 4, with a = 18.399(4) Å,b = 9.287(2) Å, and c = 12.052(2) Å, 4·H 2O, in the monoclinic space group P2 1/c, Z = 4, with a = 8.586(1) Å, b = 15.617(3) Å, c = 16.388(5) Å, and β = 90.84(2)°; and 5·3CH 3CN·0.5(toluene), in the monoclinic space group P2 1/c, Z = 4, with a = 15.003(3) Å, b = 16.253(3) Å, c = 21.196(4) Å, and β = 96.78(3)°. The structural data indicate that in complexes 1-4 the neutral o-benzoquinone diimine ligand prevails. In contrast, in 5 this ligand has predominantly o-phenylenediamide character, which would render 5 formally a mixed-valent Ru IVRu V species. On the other hand, the Ru-N bond lengths of the Ru-N-Ru moiety at 1.805(5) and 1.767(5) Å are significantly longer than those in other crystallographically characterized Ru IV=N=Ru IV units (1.72-1.74 Å). It appears that the C 6H 4(NH) 2 ligand in 5 is noninnocent and that formal oxidation state assignments to the ligands or metal centers are not possible.

OriginalsprogEngelsk
TidsskriftInorganic Chemistry
Vol/bind37
Udgave nummer1
Sider (fra-til)35-43
Antal sider9
ISSN0020-1669
StatusUdgivet - 12 jan. 1998

ID: 240004204