Cu(bapen)M(CN)4·H2O complexes exhibiting chain-like structures (bapen = N,N'-bis(3-aminopropyl)-1,2-diaminoethane, M = Ni, Pd): preparations, crystal structures, spectroscopic and magnetic properties

摘要

Single crystals of Cu(bapen)Ni(CN)4·H2O and Cu(bapen)Pd(CN)4·H2O (bapen = N,N'-bis(3-aminopro-pyl)-l,2-diaminoethane) were isolated from the aqueous systems copper(II)—bapen—[M(CN)4]~(2-) (M = Ni, Pd). Crystals of the two compounds are isostructural and are built up of two crystallographically independent quasi-linear chains [-Cu(bapen)-μ2-NC-Ni(CN)2-μ2-CN-]_n and solvate water molecules. The copper(II) centers exhibit the usual distorted octahedral coordination with one tetradentate bapen ligand in the equatorial plane (mean Cu-N are 2.030 A for Cu(bapen)Ni(CN)4·H2O and 2.018 A for Cu(bapen)Pd (CN)4·H2O), while the axial positions are occupied by nitrogen atoms from μ2-bridging cyanido ligands with longer Cu- N bonds (mean values are 2.544 A for Cu(bapen)Ni(CN)4-H20 and 2.543 A for Cu(bapen)Pd(CN)4·H2O). One of the two independent coordinated bapen ligands is disordered, as are the water molecules of crystallization. The Ni and Pd atoms in both studied compounds exhibit the usual square coordination with the bridging eyanido ligands trans to each other. Several OH···O, N-H···O and N-H··· N hydrogen bonds enhance the stability of the structures. ESR spectra corroborated the presence of Jahn-Teller anisotropy at the copper(H) atoms. Magnetic studies in the temperature range 1.8-300 K reveal that both Cu(bapen)Ni(CN)4·H2O and Cu(bapen)-Pd(CN)4·H2O follow Curie-Weiss laws with 0 = -0.51 K and 0 = —0.34 K, respectively, suggesting the presence of weak antiferromagnetic interactions.