Bis 2-pyridyl benzoquinoxaline dpb

The total time for the preparation and purification of this product is about 10 h. The ligand dpb was prepared by a modification of the method of Buu-Hoi and Saint-Ruf. (Note This procedure should be performed in a fume hood.) 

Solid 2,2 -pyridil (1.08 g 5.10 mmol) is combined with 0.82 g (5.2 mmol) of 2,3-diaminonaphthalene in a 100-mL round-bottomed flask containing a magnetic stir bar. To this is added 30 mL of absolute ethanol. The flask is equipped with a reflux condenser. This solution is then stirred and heated at reflux for 5 h. The round bottom is removed from the heat and the solution is allowed to cool to room temperature, at which time solid yellow crystals of the dpb product form. The product is removed by vacuum filtration. Purification is achieved by chromatography on adsorption alumina using methylene chloride as the eluent as described above. The desired yellow band containing the dpb product elutes prior to the unreacted starting materials. The purified product is then washed with 50 mL of diethylether and dried under vacuum for 4 h. Yield 1.14 g, 67%. 

The total time required for the preparation and purification of this product is about 3 h. This complex is prepared as above for [0s(bpy)2(dpp)](PF6)2-H20 substituting dpq (0.29 g, 1.0 mmol) for the dpp used above. 

cis-TETRAKIS(2,2 -BIPYRIDINE)- -[2,3-BIS(2-PYRIDYL) PYRAZINE]DIOSMIUM(II) HEXAFLUOROPHOSPHATE DIHYDRATE [(bpy)20s(dpp)0s(bpy)2](PF6)4 2H2O  

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Electronic coupling can be probed using electrochemistry. Brewer and Richter investigated bimetallic complexes of the form [(bpy)20s(BL)0s(bpy)2] " (BE = 2,3-bis(2-pyridyl)pyrazine (dpp), 2,3-bis(2-pyridyl)quinoxaline (dpq) or 2,3-bis(2-pyridyl)benzoquinoxaline (dpb), and bpy = 2,2 -bipyridine) by electronic absorption spectroscopy and spectroelectrochemistry. When BE = dpb, the 1/2... 

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