Binuclear rhodium(II) complexes with leucine and proline

The dimeric rhodium(II) complexes [Rh₂(leu)₄(H₂O)₂]- (ClO₄)₄ and [Rh₂(pro)₄(H₂O)₂](ClO₄)₄ have been prepared and characterized by elemental analyses, i.r., u.v.–vis. and ¹H-n.m.r. spectroscopy. The amino acid molecules are coordinated as bridging ligands via their carboxylato groups. Cyclic voltammetry in DMF has shown that the complexes undergo a quasi-reversible reduction to yield dimers containing a Rh ₂ ³⁺ core. Oxidation processes within the 0–1.5V range were not observed.     

Polarographische Bestimmung der Stabilitätskonstanten ammoniakalischer Magnesiumkomplexe

Zusammenfassung Die polarographische Methode des Indikatorions wurde zur Untersuchung der Komplexbildung des Mg²⁺-Ions mit Ammoniak verwendet. Es wurden die Stabilitätskonstanten ₁,₂,₃,₄ und ein annähernder Wert für ₅ bestimmt.

---

Investigation of stability constants of magnesium ion-ammonia complexes

The polarographic method with indicator ion was used for investigation of magnesium ion complexation with ammonia. The numerical values of the stability constants ₁,₂,₃,₄ and the approximative value of ₅ were determined.

---

---

Mit 2 Abbildungen     

Superconducting thin films of MxMo6S8 type

Thin films of M_xMo₆S₈, where M=Pb, Sn, Sn-Al and Cu, known as the Chevrel phases have been prepared by d.c. getter sputtering method and the optimal conditions of their preparation have been determined. The transition temperatures reached: 10.16, 13.66, 11.74 and 12.86 K for thin films with M=Cu, Sn, Sn-Al and Pb respectively. The highest critical fields H_c²(0) of 428 kG were obtained for Pb compounds.