Syntheses and structures of bora-amidinate lanthanide(III) complexes

The use and coordination modes of the dianionic bora-amidinate ligand in lanthanide(III) chemistry is explored. Synthetic routes to complexes of the type (DIPPN)BN-LnR (Ln = lanthanide, (DIPPN)BN = HB[N(2,6-iPr(2)-phenyl)](2), R = an amide or benzylide group) have been developed. The reaction of (DIPPN)BN-H(2) with (DMA)(3)Sm (DMA = 2-Me(2)N-benzyl) gave dark-red crystals of (DIPPN)BN-Sm(DMA) in 68% yield. The yttrium analogue, (DIPPN)BN-Y(DMA), was prepared similarly (yellow crystals, 58% yield). The reaction of (DIPPN)BN-Sm(DMA) with (Me(3)Si)(2)NH gave (DIPPN)BN-SmN(SiMe(3))(2)center dot(THF)(2) (yellow crystals, 54% yield). Crystal structure determinations of (DIPPN)BN-Sm(DMA) and (DIPPN)BN-Y(DMA) revealed dimeric complexes that are held together by Ln center dot center dot center dot DIPP interactions. The complex (DIPPN)BN-SmN(SiMe(3))(2)center dot(THF)(2) crystallized as a monomer. NMR investigations of [(DIPPN)BN-Y(DMA)](2) in benzene indicate that it is also dimeric in solution. The addition of THF resulted in its dissociation into monomeric units of (DIPPN)BN-Y(DMA)center dot(THF)(x).