Spectroscopic, magnetic, biological, and structural characterization of tetrakis(μ-3-chloropropanoato)bis(triphenylphosphine oxide)dicopper(II)

Tetrakis(μ-3-chloropropanoato)bis(triphenylphosphine oxide)dicopper(II) is formed by the reaction of the phosphine oxide on the parent copper carboxylate. It belongs to the triclinic space group [Formula: see text], with a = 8.603(6), b = 12.605(4), c = 12.624(5) Å, α = 76.94(3), β = 71.74(4), and γ = 74.42(4)°. The complex has the copper acetate dimer structure, in which two Cu atoms separated by 2.649(1) Å are bridged by four bidentate carboxylate groups (mean Cu—O = 1.969 Å). The Cu—O apical bond to triphenylphosphine oxide is relatively short (2.097(2) Å). The epr spectra of the solid are interpreted in terms of a dimeric species with a paramagnetic triplet state. The same signals are found in the spectra of frozen ethanol solutions, indicating that the dimer structure is retained. Magnetic susceptibility was determined in the range 81–293 K and the energy separation −2J = 328(4) cm⁻¹ was found between the two spin states. The phosphine oxide adduct is toxic to Escherichiacoli with ID₅₀ values near 100 μg/mL.