A novel polynitrile ligand with different coordination modes: Synthesis, structure and magnetic properties of the series [M(tcnoprOH)2(H2O)2] (M=Mn, Co and Cu) (tcnoprOH−=[(NC)2CC(OCH2CH2CH2OH)C(CN)2]−)
Abstract
A novel polynitrile ligand (tcnoprOH− = [(NC)2CC(OCH2CH2CH2OH)C(CN)2]−) with up to five potentially coordinating groups has been synthesized in a one-pot reaction from a cyclic acetal and malononitrile. The combination of this novel ligand with different transition metal ions has led to the synthesis of two different structural types with the same formula but with different coordination modes in the ligand. Mn(II) and Cu(II) lead to a μ2-N,O-coordinating mode in the series of compounds formulated as [M(N,O-tcnoprOH)2(H2O)2] (M = MnII (1) and CuII (2)), whereas Co(II) and, most probably Ni(II), lead to a μ2-N,N′-coordinating mode in [Co(N,N′-tcnoprOH)2(H2O)2] (3). Both structural types consist of linear chains of metal ions connected by a double tcnoprOH− bridge. These ligands are connected to the metal ions through one –CN and one –OH group in compounds 1 and 2 (N,O-coordinating mode) or through two –CN groups in compound 3. Magnetic measurements show that all compounds are paramagnetic with a low zero field splitting for the Mn derivative.