All wrapped up: The reaction of a 22-membered macrocycle derived from bis(o-formylphenyl)mercury and 1,2-phenylenediamine with palladium(II) results in cleavage of the macrocycle and concomitant formation of a trimetallic complex (see picture; phenyl rings truncated for clarity). The nature of the Hg(II)...Pd(II)...Hg(II) interaction was investigated by theoretical studies.

The mononucleating hydrazone ligand LH3, a condensation product of salicyloylhydrazine and (2-formylphenoxy)acetic acid, was synthesized and its coordination behavior with first row transition metal(II) ions was investigated by isolating and elucidating the structure of the complexes using elemental analysis, conductivity and magnetic susceptibility measurements, as well as IR, 1H-NMR, electronic and EPR spectral techniques. The ligand forms mononuclear metal(II) complexes of the type [CoLH(H 2O)2], [NiLH(H 2O)2], [CuLH] and [ZnLH]. The ligand field parameters, Dq, B and ? values, in the case of the cobalt and nickel complexes support not only the octahedral geometry around the metal ion, but also imply the covalent nature of the bonding in the complexes. The EPR study revealed the presence of a spin exchange interaction in the solid copper complex and the covalent nature of the bonding. The 1H-NMR study of the zinc(II) complex indicated the non-involvement of the COOH group in the coordination. The physico-chemical study supports for the presence of octahedral geometry around cobalt(II), nickel(II) and tetrahedral geometry around copper(II) and zinc(II) ions. .

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Metallophile Wechselwirkung: Ein aus Bis(o‐formylphenyl)quecksilber und 1,2‐Phenylendiamin erhaltener, 22‐gliedriger Makrocyclus reagiert mit Palladium(II) unter Spaltung des Makrocyclus und gleichzeitiger Bildung eines Trimetallkomplexes (siehe Bild; die Phenylringe sind nur ausschnittsweise gezeigt). Die Art der HgII⋅⋅⋅PdII⋅⋅⋅HgII‐Wechselwirkung wurde in theoretischen Studien untersucht.

A series of three new mononucleating thiosemicarbazone ligands possessing potential S, N, and O coordination sites have been prepared by the reaction of 2-formylphenoxy acetic acid with substituted thiosemicarbazides. Complexes of these ligands with Co II , Ni II , Cu II , and Zn II have prepared and characterized by physicochemical and spectroscopic methods. In all the complexes, the dibasic tetradentate nature of the ligand is evident.