Synthesis and characterisation of pendant-arm alcohol derivatives of [9]aneN2S and complexation with CuII ([9]aneN2S = 1-thia-4,7-diazacyclononane)

An improved detosylation of 4,7-bis(tolyl-p-sulfonyl)-1-thia-4,7-diazacyclononane to give the free amine [9]aneN2S has been accomplished using Li/NH3 or HBr/acetic acid. Reaction of [9]aneN2S with ethylene oxide, 1,1-dimethylethylene oxide and methylenecyclohexane oxide in alcoholic solution affords the potentially pentadentate ligands 4,7-bis(hydroxyethyl)-1-thia-4,7-diazacyclononane (H2L1), 4,7-bis(2-hydroxy-2-methylpropyl)-1-thia-4,7-diazacyclononane (H2L2) and 4,7-bis(2-cyclohexyl-2-hydroxymethyl)-1-thia-4,7-diazacyclononane (H2L3) respectively. The copper(II) complexes of these ligands have been prepared and reveal that increasing the steric bulk on the pendant arm has a marked effect upon the resultant co-ordination chemistry. Thus, the complex of H2L1 shows a dimeric structure [Cu2(HL1)2][PF6]2 1 in which one of the hydroxy groups has been deprotonated. With H2L2 two complexes can be isolated: the dimer [Cu2(HL2)2][PF6]2 2 and the monomer [Cu(HL2)][PF6] 3. In contrast, with H2L3 only the monomer [Cu(HL3)][PF6] 4 could be isolated. Single crystal structures of 1 and 3 have been determined. Magnetochemistry of 1 indicates that the two copper(II) centres are essentially non-coupled.