A Series of tris(boratabenzerre) lanthanum complexes Were synthesized and structurally characterized. salt elimination of anhydrous LaCl3 with Li[C5H5BR] (R = H, NEt2) provided tris(boratabenzerie) lanthanum complexes [C5H5BH3](3)-LaLiCl (I) and [C(5)H(5)BNBt(2)](3)LaLiCl(THF) (2) in high yields. Hydroboration of 1-hexene or 3-hexyne with I gave the alkyl- or alkenyl-functionalized boratabenzene lanthanum complexes, [C5H5B(CH2)(5)CH3](3)LaLiCI(THF) (3) and [C5H5BC(C2H5)= CH(C2H5)](3)LaLiCl(THF) (4), in good yields. Hydroboration of N,N'-diisopropylcarbodiimide with I gave the monohydroboration product [C5H5BN(Pr-t)CHN(Pr-i)][C5H5BH](2)La (5) due to the steric bulk of the [C5H5BN(Pr-i)CHN(Pr-i)](-) ligand. Complex 5 can undergo further hydroboration with 3-hexyne or dehydrogenative coupling with phenyl acetylene to afford [C5H5BN(Pr-i)-CHN(Pr-i)][C5H5BC(C2H5)=CH(C2H5)](2)La (6) or [C5H5BN(Pr-i)CHN(Pr-i)][C5H5BC CPh)](2)La (7).