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) were prepared in aqueous solution. In compound 1 [space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2) pm, β = 122.45(1)°], Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetate dianion and three water molecules to form a distorted octahedron. The Cu–O bonds range from 190.4(3) to 278.5(3) pm. The connection between the Cu2+ cations and the hydrogenphosphonoacetate dianions leads to a two‐dimensional structure with layers parallel to (101). The layers are linked by hydrogen bonds. In compound 2 [space group P1 (no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, α = 94.98(1)°, β = 105.71(1)°, γ = 109.84(1)°], two crystallographically independent Cu2+ cations are coordinated in a square pyramidal and an octahedral fashion, respectively. The Cu–O bonds range from 192.9(2) to 237.2(2) pm. The coordination of the phosphonoacetate 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 counterions. 1 and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie‐Weiss behavior. Compound 2 shows antiferromagnetic coupling between Cu2+ ions due to a super‐superexchange coupling. The UV/Vis spectra of 1 suggest 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 decomposition of 2 begins at 63 °C.

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3‐Phosphonopropionic Acid and (RS)‐2‐Phosphonobutyric Acid

“…Such super‐superexchange paths are also found in e.g. copper phosphates,, sodium copper methylenediphosphonate monohydrate, copper phosphonocarboxylates,, and other copper phosphonates , …”

“…The hydroxyl oxygen atom O(1) from the carboxyl group is not bonded to Cu 2+ . The coordination of O(3) and O(2) to the same Cu 2+ leads to the formation of a chelating six‐membered ring [O(2)–C(1)–C(2)–P–O(3)–Cu] as found also in other copper phosphonocarboxylates , . The P–O bond lengths in the [CPO 3 ] tetrahedron are between 151.6(3) and 153.1(4) pm and the P–C bond is 180.8(6) pm (Table ).…”

“…Ion exchange properties were found for example titanium‐, chromium‐, and aluminum 3‐phosphono‐hydrogenpropionate and zirconium diphosphonate‐phosphate hybrids, whereas cobalt 1‐(methylenephosphono)‐pyrrolidine‐2‐carboxylate can be used as catalyst for water oxidation . The coordination between bifunctional phosphonocarboxylates and metal cations leads to various structural motives . In complex compounds the anion of e.g.…”

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3-Phosphonopropionic Acid and (RS)-2-Phosphonobutyric Acid

“…A possible super-superexchange path is CuO(3)PO(5)Cu ( Figure 17 Such super-superexchange paths are also found in e.g. copper phosphates [ 53 , 54 ] , sodium copper methylenediphosphonate monohydrate [55] , copper phosphonocarboxylates [15,26] , and other copper phosphonates [56,57] . The diffuse reflectance UV/Vis spectra for 1 and 2 are shown in Figure 18 and 19.…”

“…(3)Cu] as found also in other copper phosphonocarboxylates. [15,38 ] The PO bond lengths in the [CPO3] tetrahedron are between 151.6(3) and 153.1(4) pm and the PC bond is 180.8(6) pm ( Table 5). The CO bond lengths within the carboxyl group are 122.1 (7) pm and 130.2(8) pm, indicating double and single bond character, respectively.…”