Synthesis and Crystal Structures of Three Carboxylate- Bridged Tetranuclear Copper(II)–Lanthanide(III) Complexes of Ph3P+CH2CH2CO2−

Abstract

Three tetranuclear copper(II)–lanthanide(III) complexes of triphenylphosphoniopropionate (Ph₃P⁺CH₂CH₂CO₂⁻,tppp), namely [Cu₂Ln₂(tppp)₈(H₂O)₈](ClO₄)₁₀·2H 2 O [Ln = Eu^III, Nd^III or Ce^III], were synthesized and characterized by crystallography. The Eu^III complex crystallizes in the triclinic space group P1 – with a 16.249(7), b 17.185(11), c 17.807(11) Å, α 69.750(10), β 89.230(10), γ 84.070(10)˚, V 4639(5) ų, Z 1. In the crystal structures, four tppp ligands bridge a pair of Cu^II and tetraaquo-Eu^III atoms (Cu···Eu 3.527(2) Å) through their µ₂-carboxylato ends to form a dinuclear subunit; two of these subunits are additionally linked by one of the Cu^II -bonded carboxylato oxygen ends, across a centre of inversion, to furnish a dimeric tetranuclear [Cu(tppp)₄ Eu(H₂O)₄]₂ species (Cu···Cu 3.323(2) Å). This Cu^II -bonded oxygen atom occupies the apical site of the square-pyramidal coordination environment of the Cu^II atom. The Eu^III atom is eight-coordinated in a square-antiprismatic geometry. The Nd^III and Ce^III complexes are isomorphous to the Eu^III complex, and only minor differences in bond lengths and bond angles involving the metal atoms are noted.