Novel 1,3,2-diazabora-[3]ferrocenophanes and a 1,4,2,3-diazadibora-[4]ferrocenophane

1,3,2-Diazabora-[3]ferrocenophanes bearing various functionalities at the boron atom are readily accessible by the reaction of the dilithiated 1,1′-bis(trimethylsilylamino)ferrocene with boron halides. Strong endocyclic BN(pp)π interactions are indicated by an essentially planar arrangement of the atoms Fe, C1, N1, B, N2 and C1′, as shown by X-ray analysis and NMR spectroscopy.