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

Single crystals of Cu(bapen)Ni(CN)(4)center dot H2O and Cu(bapen)Pd(CN)(4)center dot H2O (bapen = N,N'-bis(3-aminopropyl)-1,2-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)-mu(2)-NC-Ni(CN)(2)-mu(2)-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 for Cu(bapen)Ni(CN)(4)center dot H2O and 2.018 for Cu(bapen)Pd(CN)(4)center dot H2O), while the axial positions are occupied by nitrogen atoms from mu(2)-bridging cyanido ligands with longer Cu-N bonds (mean values are 2.544 for Cu(bapen)Ni(CN)(4)center dot H2O and 2.543 for Cu(bapen)Pd(CN)(4)center dot 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 cyanido ligands trans to each other. Several OH center dot center dot center dot O, N-H center dot center dot center dot O and N-H center dot center dot center dot N hydrogen bonds enhance the stability of the structures. ESR spectra corroborated the presence of Jahn-Teller anisotropy at the copper(II) atoms. Magnetic studies in the temperature range 1.8-300 K reveal that both Cu(bapen)Ni(CN)(4)center dot H2O and Cu(bapen)Pd(CN)(4)center dot H2O follow Curie-Weiss laws with theta A = -0.51 K and theta = -0.34 K, respectively, suggesting the presence of weak antiferromagnetic interactions.