Binuclear metal carbonyl DAB complexes VIII. The syntheses of Os2(CO)6(DAB) complexes (DAB = 1,4-diazabutadiene). Spectroscopic characterization and comparison with analogous iron and ruthenium complexes

Abstract

The reaction of Os{3}(CO){1}{2} with glyoxalbis(alkylimine) (alkyl = i-Pr, t-Bu) yielded Os{2}(CO){6}(DAB) complexes. The complexes have been characterized by field desorption mass spectrometry, }1{H NMR and IR spectroscopy. They are isostructural with Fe{2}(CO){6}(DAB) and Ru{2}(CO){6}(DAB). In these complexes the DAB ligand is a six-electron donor system coordinated via two lone pairs and one pair of @p electrons. The complex Os{3}(CO){9}(i-PrN@?CH@?CH@?N-iPr) was also isolated. This is the first example of a trinuclear metal carbonyl DAB complex, in which the DAB ligand is @s-N, @s-N',@h}2{-C@?N coordinated. The reactions of the metal carbonyl complexes of the iron triad with DAB ligands are compared, and the ruthenium system shown to be the most versatile.