Synthesis, characterization, reactivity and computational studies of new rhenium(I) complexes with thiosemicarbazone ligands derived from 4-(methylthio)benzaldehyde

详细信息    查看全文

• 作者：Ara N&#xfa ; &#xf1 ; ez-Montenegro^a ; Rosa Carballo^a ; José ; M. Hermida-Ram&#xf3 ; n^b ; Ezequiel M. Vá ; zquez-L&#xf3 ; pez^a ; ^{ezequiel@uvigo.es"" rel=""nofollow}
• 关键词：Thiosemicarbazone ; Thiadiazole ; Rhenium complexes ; Carbonyl complexes ; Crystal structures
• 刊名：Polyhedron
• 出版年：2011
• 出版时间：2 August 2011
• 年：2011
• 卷：30
• 期：12
• 页码：2146-2156
• 全文大小：1173 K

文摘

N-thioamide thiosemicarbazone derived from 4-(methylthio)benzaldehyde (R = H, HL¹; R = Me, HL² and R = Ph, HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in methanol gave the adducts [ReX(CO)₃(HLⁿ)] (1a X = Cl, n = 1; 1a′ X = Br, n = 1; 1b X = Cl, n = 2; 1b′ X = Br, n = 2; 1c X = Cl, n = 3; 1c′ X = Br, n = 3) in good yield.

All the compounds have been characterized by elemental analysis, mass spectrometry (ESI), IR and ¹H NMR spectroscopic methods. Moreover, the structures of HL², HL³, HL³·(CH₃)₂SO and 1b′·H₂O were also elucidated by X-ray diffraction. In 1b′, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms (ba;S,N³) forming a five-membered chelate ring, as well as three carbonyl and bromide ligands. The resulting coordination polyhedron can be described as a distorted octahedron.

The structure of the dimers is based on rhenium(I) thiosemicarbazonates [Re₂(L¹)₂(CO)₆] (2a), [Re₂(L²)₂(CO)₆] (2b) and [Re₂(L³)₂(CO)₆] (2c) as determined by X-ray studies. Methods of synthesis were optimized to obtain amounts of these thiosemicarbazonate complexes. In these compounds the dimer structures are achieved by Re–S–Re bridges, where S is the thiolate sulphur from a ba;S,N³-bidentate thiosemicarbazonate ligand.

Some single crystals isolated in the synthesis of 2b contain [Re(L⁴)(L²)(CO)₃] (3b) where L⁴ (=2-methylamine-5-(para-methylsulfanephenyl)-1,3,4-thiadiazole) is originated in a cyclization process of the thiosemicarbazone. Furthermore, the rhenium atom is coordinate by the sulphur and the thioamidic nitrogen of the thiosemicarbazonate (ba;S,N²) affording a four-membered chelate ring.