Synthesis and structure of oxorhenium(V) complexes containing a terdentate imidazole ligand. A route to mixed ‘3?+?2' complexes r saccharinate) and the single-crystal X-ray structure of the saccharinate salt, trans -[Co(en)2(NO2)2](C7H4NSO3) · H2O

The neutral mononuclear complex [ReOBr2(ami)] ( 1 ) [Hami?=?2-(1-ethanolaminomethyl)-1-methylimidazole] was prepared by reaction of ( n -Bu4N)[ReOBr4(OPPh3)] with an equimolar amount of Hami in acetonitrile. Further reaction of 1 with disodium oxalate (Na2ox) in methanol yielded the mixed didentate–terdentate complex [ReO(ox)(ami)] ( 2 ). These compounds were characterized by spectroscopy and X-ray crystallography. Both complexes have distorted octahedral geometry with the alcoholate oxygen of ami – coordinated trans to the oxo group. In 1 the Br–Re–Br angle equals 89.91(3)° and in 2 the oxalate has a bite angle of 81.0(2)°.