Recent developments in the chemistry of aldimines of boron are described.Unsymmetrical borole complexes of aldimines derived from heterocyclic aldimineshave been characterized on the basis of IR, 1H-NMR, 13C-NMRand 11B-NMR spectral studies and elemental analysis and molecularweight determinations. Spectral studies confirmed that the aldimines actin a monobasic bidentate fashion, rendering the non-metal tetracoordinated.The new complexes of the types [(B(C3H6O2)(Ln)] and [B(C4H8O2)(Ln)] were obtained by 1:1 molar reactions of unsymmetrical monoisopropoxyborane with heterocyclic aldimines in dry benzene. The liberated isopropanolwas fractionated off azeotropically with benzene and estimated.