The use of substituted terpyridyls in the synthesis of alternating site, bimetallic, coordination complexes.

摘要

Our interests lie in the field of molecular magnetism. In this field magnetic exchange is mediated by a molecular unit rather than the direct overlap of the magnetic orbitals. Our ultimate goal is the development of alternating site, bimetallic, coordination polymers. These materials should be a special class of antiferromagnets called ferrimagnets.; These coordination polymers will be developed through the use of 4{dollar}spprime{dollar}-substituted terpyridine. Reaction of a metal salt with the terpyridine ligand results in a stable coordination complex. If the 4{dollar}spprime{dollar}-substitution is a mercapto or hydroxyl group, deprotonation will result in an external binding site. Subsequent reaction of the deprotonated coordination complex with a different metal salt results in the self assembly of an alternating site, bimetallic, coordination polymer.; Initial attempts to create these coordination polymers were carried out using 4{dollar}spprime{dollar}-methylthio-2,2{dollar}spprime{dollar}:6{dollar}spprime{dollar},2{dollar}sp{lcub}primeprime{rcub}{dollar}-terpyridine (MeStrpy). The complexes, (M(MeStrpy){dollar}sb2{dollar}) (ClO{dollar}sb4)sb2{dollar} (M = Mn, Fe, Co, Ni, Cu, Zn), were prepared in high yield X-ray analysis of the products confirmed their structure. Attempts to remove the methyl group were unsuccessful.; The second substituted terpyridine studied was 4{dollar}spprime{dollar}-hydroxy-2,2{dollar}spprime{dollar}:6{dollar}spprime{dollar}, 2{dollar}sp{lcub}primeprime{rcub}{dollar}-terpyridine (trpyOH). Reaction of this ligand with metal perchlorate salts resulted in the formation of complexes of the type, (M(trpyOH){dollar}sb2{dollar}) (ClO{dollar}sb4)sb2{dollar} (M = Mn, Fe, Co, Ni, Cu). Deprotonation of the coordination complex was carried using sodium methoxide for all of the metal complexes. The deprotonated copper brick (Cu(trpyO){dollar}sb2{dollar}) was isolated. The deprotonated brick was then allowed to react with a metal(II) perchlorate salt to form the bimetallic materials (M{dollar}spprime{dollar}Cu(trpyO){dollar}sb2{dollar}) (ClO{dollar}sb4)sb2{dollar} (M{dollar}spprime{dollar} = Mn, Fe, Co, Ni, Cu). Analysis of these complexes showed that the materials are based upon the deprotonated copper complex and that there is more than one metal present.; At this time, we have developed several bimetallic materials based on the ligand, 4{dollar}spprime{dollar}-hydroxy-2,2{dollar}spprime{dollar}:6{dollar}spprime{dollar},2{dollar}sp{lcub}primeprime{rcub}{dollar}-terpyridine. Further magnetic studies are required to determine whether these materials are truly ferrimagnets as we set out to develop. However, this work will allow us to determine the utility of terpyridine based ligands in developing magnetic materials.