Metallomacrocycles from ditopic chiral scorpionate ligands

Rare examples of heteroditopic scorpionate ligands m-(pz(HO)BtBu)(pz2BtBu)C6H4]2- (m]2-) and p-(pz(HO)BtBu)(pz2BtBu)C6H4]2- (p]2-) are reported. As a unique feature, both ligands possess a chiral boron centre. Treatment of m]2- and p]2- with FeII and CoII ions, respectively, gives the dinuclear metallomacrocycles FeII2(micro-m)2] and CoII2(micro-p)2]. The molecular structures of the colourless complex FeII2(micro-m)2] and the red-purple complex CoII2(micro-p)2] have been determined by X-ray crystallography. To meet the geometric requirements of macrocycle formation, the two asymmetric boron centres have opposite absolute configurations in the case of FeII2(micro-m)2] and the same configuration in CoII2(micro-p)2].