Synthesis, Crystal Structure and Characterization of Two Novel One- and Two-Dimensionally Polymeric Copper(II) Phosphonoacetates

Abstract

Blue single crystals of Cu[μ2-OOC(CH2)PO3H].2H2O (1) and Cu1.5[μ3-OOC(CH2)PO3].5H2O (2) havebeen prepared in aqueous solution. 1: Space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2)pm, beta = 122.45(1)°. Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetatedianion and three water molecules to form a distorted octahedron. The Cu-O bonds range from 190.4(3) to278.5(3) pm. The connection between the Cu2+ cations and the hydrogenphosphonoacetate dianions leads to atwo-dimensional structure with layers parallel to ( 01). The layers are linked by hydrogen bonds. 2: Space group(no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, alpha = 94.98(1)°, beta = 105.71(1)°, gamma = 109.84(1)°.There are two crystallographically independent Cu2+ cations coordinated in a square pyramidal and an octahedralfashion, respectively. The Cu-O bonds range from 192.9(2) to 237.2(2) pm. The coordination of thephosphonoacetate trianion to Cu(1) results in infinite polyanionic chains parallel to [100] with a composition of{Cu(H2O)[OOC(CH2)PO3]}nn-. Hydrated Cu(2) cations are accommodated between the chains as counter ions. 1and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie-Weiss behaviour. Compound 2 shows antiferromagnetic coupling between Cu2+ ions due to a super-superexchangecoupling. The UV/Vis spectra of 1 suggests three d-d transition bands at 763 nm (2B1 - 2E), 878 nm (2B1 -2B2), and 1061 nm (2B1 - 2A1). Thermoanalytical investigations in air show that compound 1 is stable up to 165°C, whereas the decomposition of 2 begins at 63 °C.