Different coordination patterns for two related unsymmetrical compartmental ligands: crystal structures and IR analysis of [Cu(C21H21O2N3)(OH2)(ClO4)]ClO4·2H2O and [Zn2(C22H21O3N2)(C22H20O3N2)]ClO4
The crystal structures of the new complexes [Cu(HL1)(OH2)(ClO4)]ClO4·2H2O (1) and [Zn2(HL2)(L2)]ClO4 (2), derived from two related, phenol-based compartmental ligands, are described. Compound 2 constitutes the first report of a complex obtained from H2L2. The metal compounds are structurally different; 2 is a dimer in which all the heteroatoms of the ligand take part in coordination, while 1 is mononuclear containing a pair of cis-oriented ligands that complete an “open” coordination sphere, in which the aldehyde group of HL1 is not involved. The protonation status of the central phenol groups of HL1 and H2L2 are also dissimilar between the complexes. Infrared vibrational analyses of both complexes, as well as their respective ligands, were performed to connect the observed spectral features with the structural properties of the solids. While some distinctive bands shifted upon complexation, it was not possible to confirm involvement of the aromatic aldehyde group in coordination by this technique. 1H NMR experiments involving 2 suggest that its particular protonation status is maintained upon dissolution in d6-DMSO.
