- Preparation and characterization of oxorhenium(V) complexes with 2,2'-biimidazole: The strong affinity of coordinated biimidazole for chloride ions via N-H···Cl- hydrogen bonding
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N,N'-Dimethylbiimidazole and bipyridine (N-N) react with ReOCl3(OPPh3)(Me2S) to give mer-ReOCl3(N-N) compounds. Nonmethylated biimidazole forms a trans-O,O [ReOCl2(OPPh3)(biimH2)]+ cation, which is tightly associated with the Cl- counterion via N-H···Cl- hydrogen bonding. Hydrolysis of ReOCl3(biimMe2) in wet acetone (5% water) leads to the linear oxo-bridged dinuclear species [{OReCl2(biimMe2)}2(μ-O)] containing chelated biimMe2. Acetone solutions containing only 1% water yield the bent oxo-bridged dinuclear species [{OReCl2}2(μ-O)(μ-biimMe2)2], where each Re center retains the ReO2Cl2N2 coordination but the biimMe2 ligands are bridging. The linear oxo-bridged [{OReCl2(biimH2)}2(μ-O)] complex obtained with nonmethylated biimidazole includes two Cl- ions held via N-H···Cl- hydrogen bonds, leading to a dianionic [{OReCl2(biimH2···Cl)}2(μ-O)]2- unit in the crystals of the PPh4+ salt. The compounds are characterized by IR and NMR spectroscopies, and the structures of [ReOCl2(OPPh3)(biimH2)]Cl, [{OReCl2(biimH2)}2(μ-O)](PPh4Cl)2·2H2O, and [{OReCl2}2-(μ-O)(μ-biimMe2)2]·acetone are determined by X-ray diffraction.
- Fortin,Beauchamp
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