Mononuclear and unsymmetric dinuclear complexes of the tripodal ligand 2-hydroxyethyl-bis(2-{pyrid-2-yl}ethyl)amine

Reaction of bis(2-{pyrid-2-yl}ethyl)amine with 2-bromoethanol in the presence of Na2CO3 yields the title ligand, LH. Treatment of LH with the CuBr2 or Zn(O2CMe)2 · 2H2O yields pure crystalline [CuBr(LH)]Br · H2O (1 · H2O) and [Zn2(O2CMe)2(μ-O2CMe)(μ-L)] (2). Reaction of LH with Cu(O2CMe)2 · H2O affords a low yield of [Cu2Cl2(μ-O2CMe)(μ-L)] (3), the Cl− ligands apparently originating from the CH2Cl2 crystallization solvent. Compound 1 · H2O is a near-regular square-pyramidal complex with a neutral, protonated LH ligand. In contrast, 2 and 3 are both unusual unsymmetric dinuclear complexes, with a five-coordinate [ML(O2CMe)] (M = Zn or Cu) unit linked to a second metal ion through the deprotonated ligand alkoxide donor and O,O′-bridging acetate ligand.

Graphical abstractReaction of bis(2-{pyrid-2-yl}ethyl)amine with 2-bromoethanol in the presence of Na2CO3 yields the title ligand, LH. Treatment of LH with the appropriate metal salt yields pure crystalline [CuBr(LH)]Br · H2O and [Zn2(O2CMe)2(μ-O2CMe)(μ-L)] (shown). The crystal structure of [Cu2Cl2(μ-O2CMe)(μ-L)] is also presented.Figure optionsDownload full-size imageDownload as PowerPoint slide