Synthesis and physicochemical study of Ni-II complexes with tetradentate acyclic and macrocyclic N2S2 ligands as thiosalen analogsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:N,N'-Polymethylenebis(thiosalicylidene)iminate and macrocyclic dithiadiazadibenzo-cycloalkadiene complexes of nickel(II) were synthesized and their electrochemical and spectroscopic properties were studied. Dithiadiazadibenzocycloalkadiene complexes containing two DMSO molecules coordinated to Ni2+ and two outer-sphere ClO4- anions were synthesized by the reaction of the corresponding macrocyclic ligands with Ni(ClO4)(2)center dot 6H(2)O. The structure of 3,6-dithia-10,14-diazadibenzo[a,g]cyclopentadeca-9,14-dienylnickel(II)[b is(di-methyl sulfoxide) bis-perchlorate] was established by X-ray diffraction. The UV-Vis spectroscopic data are consistent with octahedral structures of diiminobis(sulfide) complexes, a square-planar structure of the thiosalen complex, and distorted tetrahedral structures of other diiminodithiolate complexes. The reaction of S-tert-butylthiosalicylaldeliyde with hydrazine hydrate afforded di(ortho-tert-butylthiobenzal)azine. The reaction of the latter with anhydrous NiCl2 produced a colored complex with the simplest molecular formula Ni(C16H12N2S2) in 15% yield. Semiempirical PM3(tm) calculations and the results of UV-Vis, ESR, and H-1 NMR spectroscopy demonstrate that this complex has most probably a dimeric structure, in which two Ni centers adopt a nearly square-planar configuration. The complexes are clearly divided into two types according to their electrochemical behavior in DMF solutions. The type I is characterized by reversibility of the first reduction steps. The type 2 is characterized by irreversible two-electron reduction as the first step accompanied by deposition of Ni metal on the electrode surface. Rapid electrochemically initiated alkylation occurs in the presence of various alkylating agents ((BuI)-I-n, (BuBr)-Br-n, (DmgH)(2)CoCH3) in a solution of complex 1 in DMF.