Μeff Values Research Articles

ChemInform Abstract: COMPLEXES OF METAL IONS WITH PHOSPHORUS OR ARSENIC CONTAINING LIGANDS. PART XVIII. CHELATES OF O‐PHENYLENEBIS(DIARYLARSINES) WITH COBALT(II) AND NICKEL(II) HALIDES AND PSEUDOHALIDES

AbstractDie Chelatkomplexe (I) und (II) werden durch Umsetzung entsprechender Ni‐halogenide und in situ‐Co‐diisothiocyanat mit den Diarsinen in n‐Butanol/ Methylenchlorid dargestellt.

Complexes of metal ions with phosphorus or arsenic containing ligands. Part XVIII. Chelates ofo-phenylenebis(diarylarsines) with cobalt(II) and nickel(II) halides and pseudohalides

Ten complexes of nickel(II) and cobalt(II) witho-phenylenebis(diphenylarsine), (pdpa) ando-phenylenebis(di-p-tolylarsine), (pdta) have been synthesised. The stoichiometry of complexes is markedly dependent upon the reaction temperature, thus reaction atca. 0° gives the M(A-A)2X2 chelates, [M = Ni, X = Br, (A-A) = pdpa; M = Ni, X = I, (A-A) = pdpa, pdta; M = Co, X = CNS, (A-A) = pdpa] whereas at higher temperatures the M(A-A)X2 chelates [M = Ni, X = Br, I, (A-A) = pdpa, pdta; M = Co, X = CNS, (A-A) = pdpa or pdta] are obtained. The Ni(A-A)2I2 compounds can be converted into Ni(A-A)I2 by boiling under reflux in n-BuOH; the conversion can be reversed by cooling a CH2Cl2 solution of the latter at or below 0°. Stereochemical assignments of all the new complexes have been made on the basis of room temperature μeff values, molar conductance, i.r. and u.v. data.

The preparation and properties of cobalt(II) tellurates

Cobalt(II) tellurates with the composition CoTeO4, CoTeO4.1/2 H2O and Co3TeO6 were prepared. The first two are cubic with octahedral coordination around the cobalt atom and with TeO6 octahedra joined at the edges. In Co3TeO6, which is isostructural with Ni3TeO6, the TeO6 octahedra are isolated. At least one cobalt atom is tetrahedrally coordinated by oxygen atoms. The high values of the temperature independent paramagnetism, 11 m3 kg-1, and the Weiss constant, Θ = -64 K, indicate marked magnetic exchange interaction. The thermal decomposition of all three tellurates leads to formation of cobalt tellurates and finally to CoO and TeO2. At laboratory temperature all three substances are paramagnetic with μeff values corresponding to divalent cobalt.

ChemInform Abstract: VANADIUM(III) CHLORO AND BROMO COMPLEXES WITH TETRADENTATE SCHIFF BASE LIGANDS

Die Schiffschen Basen reagieren mit VCl3 in Pyridinlösung zu den V(III)-Chelaten (Ia), aus denen durch Umsetzung mit LiBr die entsprechenden Bromoderivate (Ib) erhalten werden können.

Vanadium(III) chloro and bromo complexes with tetradentate Schiff base ligands

Vanadium(III) Schiff base chelates of the types V(chel)Cl,py (chel = saen, saph) and V(saen)Cl,py2 have been synthesized by allowing VCl3 and the ligand to react in pyridine solutions. The bromo derivatives V(saen)Br,py and V(saph)Br,py2 can be obtained by LiBr substitution. The magnetic and spectral properties of the complexes are consistent with tetragonally distorted octahedral structures, though the μeff value for V(saen)Cl,py is slightly lower than expected and difficult to explain with certainty.