Contributions to the Chemistry of Boron, 233 . Reactions of a 1,2,3,4‐Diphosphadiboretane with Some Carbonylmetal Compounds

1,2‐Di‐ tert ‐butyl‐3‐(diisopropylamino)‐4‐(dimethylamino)‐ 1,2,3,4‐diphosphadiboretane ( 1 ) reacts with Fe 2 (CO) 9 to give two isomeric tetracarbonyliron complexes 2, 3 with P–Fe bonds and a bis(tetracarbonyliron) complex 4 . In contrast, 1 displaces the olefinic ligand from tetracarbonyl(η 4 ‐norbornadiene)metal (metal = Cr, Mo) to form the tetracarbonylmetal complexes 5 and 6 with a rearranged ligand molecule, i.e. a 1,3,2,4‐diphosphadiboretane. This process is accompanied by a change of the tert ‐butyl groups from an anti orientation in 1 to a syn orientation in 5 as shown by X‐ray crystallography.