Metal ion distribution and solubility of Mn 1−x Cu x (HCOO) 2 · 2 H 2 O Mixed Crystals [1–5]

The metal ion distribution on the two metal sites of monoclinic Mn 1−x Cu x (HCOO) 2 · 2(H,D) 2 O mixed crystals are studied by infrared and Raman spectroscopic methods. The spectral regions 3 200–3 400 cm −1 ( v OH ), 2 875–2 990 cm −1 ( v CH ), 2 330–2 500 cm −1 ( v OD of matrix isolated HDO molecules), 1 350–1 400 cm −1 (symmetric CO 2 stretching modes), 570–950 cm −1 (H 2 O librations), and 490 cm −1 (MO lattice modes) are mostly sensitive to the metal ions present. The frequency shifts of these bands with increasing content of copper show that Cu 2+ prefers the M(1) site, coordinated by HCOO − only. The strengths of the hydrogen bonds increase on going from manganese to copper formate, due to the increased synergetic effect of Cu 2+ . Solubility and X‐ray data of the mixed crystals are included. Irrespective of the same crystal structure, two series of mixed crystals are formed: eutonic area at 0.65 ≥ x ≥ 0.5.