Lanthanoid‐Peroxo‐Komplexe mit μ3‐η2:η2:η2‐(O22—)‐Koordination. Die Kristallstrukturen von [Ln4(O2)2Cl8(Py)10] · Py mit Ln = Sm,Eu, Gd

Lanthanoid Peroxo Complexes with μ₃‐η²:η²:η²‐(O₂^2—) Coordination. Crystal Structures of [Ln₄(O₂)₂Cl₈(Py)₁₀] · Py mit Ln = Sm, Eu, Gd The four‐nuclear peroxo complexes [Ln₄(O₂)₂Cl₈(Py)₁₀]·py (py = pyridine) with Ln = Sm ( 1 ·py), Eu ( 2 ·py) und Gd ( 3 ·py) are formed as pale yellow ( 1 ·py) and colourless ( 2 ·py and 3 ·py) crystals by action of atmospheric oxygen on heated solutions of the anhydrous trichlorides LnCl₃ in pyridine/ diacetone alcohol (4‐hydroxy‐4‐methyl‐2‐pentanone). According to the X‐ray structural analyses the three complexes crystallize isostructural in the triclinic space group PP1¯ with two formula units per unit cell. 1—3 form centrosymmetrical molecular structures, in which the four lanthanoid atoms in coplanar array are linked via the two peroxo groups in a hitherto unobserved μ₃‐η²:η²:η² coordination. Additionally, they are bonded by four �μchloro bridges. Two of the Ln atoms complete their coordination sphere by three pyridine molecules each, the other two by two chlorine atoms and two pyridine molecules. The gadolinium compound is additionally characterized by its complete vibrational spectrum (i.r. and Raman).