No abstract

No abstract

The reaction of cadmium salts with various amounts of the tridentate NS 2 -chelating ligands 1-(2-mercapto-acetophenone)-4-triphenylmethylthiosemicarbazone (H 2 L 1 ) and 1-(5-mercapto-3-methyl-1-phenylpyrazole-4-carboxaldehyde)-4-triphenyl-methylthiosemicarbazone (H 2 L 2 ) in the presence of bases like N-methylimidazole (N±MeIm), pyridine (py) or triethylamine (Et 3 N) provided a series of novel mono-, di-, tri-and heptanuclear cadmium complexes. They are of the general formulas [CdL 1 (N±MeIm)] 2 (1), [CdL 1 (py)] 2 (2), [CdL 2 (N±MeIm)] 2 (3), [CdL 2 (py) 3 ]0 .25 C 6 H 14´0 .5 py (4), [Et 3 NH] 2 [Cd 3 L 2 4 ]´7 MeOH (5), [Et 3 NH] 2 [Cd 3 L 1 4 ] (6) and [Et 3 NH] 2 [Cd 7 L 2 8 ]´14 MeOH (7). The compounds were characterized by elemental analysis, IR-and 1 H-NMR-spectroscopy. Single-crystal X-ray struc-ture analyses are reported for the complexes 2, 4, 5 and 7. While 2 has a dimeric structure where each cadmium ion is pentacoordinated in a N 2 S 3 -environment, 4 consists of a monomeric cadmium center with distorted octahedral N 4 S 2coordination. The complexes 5 and 7 exhibit new structural types for tri-and heptanuclear cadmium compounds. It is shown that sulfur bridging might proceed via arylthiolates, iminothiolates or even both functions of the ligand. Aggregation is influenced by various factors like solvents, counterions and ligand properties.Koordinationsverhalten tridentater NS 2 -Donor-Liganden mit Cadmium: Synthese und Kristallstrukturen neuer Komplexverbindungen Inhaltsu È bersicht. Die Reaktion von Cadmiumsalzen mit unterschiedlichen Mengen der dreifach chelatisierenden Liganden 1-(2-Mercapto-acetophenon)-4-triphenylmethylthiosemicarbazon (H 2 L 1 ) und 1-(5-Mercapto-3-methyl-1phenylpyrazole-4-carboxaldehyde)-4-triphenylmethylthiosemicarbazone (H 2 L 2 ) in Gegenwart verschiedener Basen wie N-Methylimidazol (N±MeIm), Pyridin (py) oder Triethylamin (Et 3 N) ergab eine Reihe neuer mono-, di-, triund heptanuklearer Cadmiumkomplexe mit folgenden Strukturformeln: [CdL 1 (N±MeIm)] 2 (1), [CdL 1 (py)] 2 (2), [CdL 2 (N±MeIm)] 2 (3), [CdL 2 (py) 3 ]´0.25 C 6 H 14´0 .5 py (4), [Et 3 NH] 2 [Cd 3 L 2 4 ]´7 MeOH (5), [Et 3 NH] 2 [Cd 3 L 1 4 ] (6) und [Et 3 NH] 2 [Cd 7 L 2 8 ]´14 MeOH (7). Die Verbindungen wurden durch Elementaranalysen, IR-und 1 H-NMR-Spektroskopie charakterisiert. Ro È ntgenstrukturanalysen wurden fu È r die Komplexe 2, 4, 5 und 7 durchgefu È hrt. Wa È hrend 2 eine dimere Struktur hat, in der jedes Cadmiumatom in einer N 2 S 3 -Umgebung fu È nffach koordiniert ist, ist 4 ein Monomer mit einer verzerrt oktaedrischen N 4 S 2 -Koordination. 5 und 7 stellen neue Strukturtypen fu È r tri-und heptanukleare Cadmiumkomplexe dar. Die Verbru È ckung durch die Schwefelatome geschieht einerseits nur u È ber die Aryl-oder Iminothiolate und andererseits u È ber beide Funktionen des Liganden. Der Umfang der Aggregation wird dabei durch verschiedene Faktoren wie Lo È sungsmittel, Gegenionen und Ligandeigenschaften beeinfluût.

Four different disulfides, [2,2′‐dithiobis‐(2‐mercaptoacetophenone)]‐4‐triphenylmethylthiosemicarbazone (1), [5,5′‐dithiobis‐(4‐formyl‐3‐methyl‐1‐phenylpyrazole)]‐4‐triphenylmethylthiosemicarbazone (2), bis[1‐(2‐mercaptophenyl)‐2‐(4‐(1‐phenyl‐3‐methyl)pyrazole)‐azaethene]di‐sulfide (3) and bis[1‐phenyl‐2‐(4‐(1‐phenyl‐3‐methyl‐5‐mercapto) pyrazole)‐azaethene]disulfide (4) were synthesized by Schiff base reactions. Their electrochemical behaviour was examined by cyclic voltammetry. The results show low potentials for the disulfide reduction so that these compounds are suitable for the syntheses of tridentate thiolate ligands from disulfides by electrochemical cleavage. In addition compounds 2 and 4 were characterized by X‐ray structure determination. The structures show significant differences of the S—S bonds and angles as compared to other disulfides without bulky substituents.