Iron(ii) and cobalt(ii) complexes based on anionic phenanthroline-imidazolate ligands: reversible single-crystal-to-single-crystal transformations†
Abstract
A series of low-spin FeII and CoII complexes based on phenanthroline-imidazolate (PIMP) ligands are reported. The FeII complex (H9O4)[Fe(PIMP)3]·(C4H10O)2(H2O) (1a) shows reversible crystalline phase transformations to afford two new phases (H9O4)[Fe(PIMP)3]·(H2O) (1b) and (H9O4)[Fe(PIMP)3]·(C8H18O)(C4H10O)(H2O) (1c) by release of diethyl ether and absorption of diethyl/dibutyl ether, respectively. This reversible uptake/release of solvent molecules is a clear example of single-crystal-to-single-crystal transformation involving a discrete metal complex. On the other hand, the corresponding CoII complex (H9O4)[Co(PIMP)3]·(C4H10O)2(H2O)2 (2) does not exhibit similar phase transformations. In the neutral complexes [Fe(H-TfPIMP)(TfPIMP)2]·(EtOH)4(H2O)7 (3) and [Co(H-TfPIMP)(TfPIMP)2]·(EtOH)2(H2O)2 (4), which crystallized in the polar space group Pna21 and in the centrosymmetric space group P21/n, respectively, one of the imidazole ligands was not deprotonated.