Based on Homonuclear Dimetal Units

The Fe2B2 cores of both 2 and its anion are hydrogen rich and as such are suitable precursors for cluster expansion reactions. Such reactivity has been exploited in the formation of HFe4(CO)12BH2 ( 10% yield) by reaction of 2 with Fe2(CO)9 and of [HFe4(CO),2BH] ( 10% yield) by reaction of [Fe2(CO)6B2H5] with Fe2(CO)9. The anion reacts more rapidly than does the neutral ferraborane both reactions are easily monitored by 11B-NMR spectroscopy (76) (see also Section IV). 

The red compound HMn2(CO)6(B2H6)Mn(CO)4 exhibits an interesting bridging mode for the diborane ligand. The latter uses all six of its hydro- 

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