Structural Flexibility and Role of Vicinal 2-Thienyl Rings in 2,3-Dicyano-5,6-di(2-thienyl)-1,4-pyrazine, [(CN)2Th2Pyz], Its Palladium(II) Complex [(CN)2Th2

详细信息    查看全文

• 作者：Maria Pia Donzello ; Giorgia De Mori ; Elisa Viola ; Claudio Ercolani ; Enrico Bodo ; Luisa Mannina ; Donatella Capitani ; Corrado Rizzoli ; Lorenzo Gontrani ; Giuliana Aquilanti ; Karl M. Kadish ; Paola D鈥橝ngelo
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：December 5, 2011
• 年：2011
• 卷：50
• 期：23
• 页码：12116-12125
• 全文大小：960K
• 年卷期：v.50,no.23(December 5, 2011)
• ISSN：1520-510X

文摘

The solid state and solution structure of 2,3-dicyano-5,6-di(2-thienyl)-1,4-pyrazine, [(CN)₂Th₂Pyz], and its Pd^II derivative, [(CN)₂Th₂Pyz(PdCl₂)₂]路H₂O, formed by reaction of [(CN)₂Th₂Pyz] with [(C₆H₅CN)₂PdCl₂] were characterized by X-ray, UV鈥搗isible, ¹H and ¹³C NMR, and extended X-ray absorption fine structure (EXAFS) spectral measurements. The X-ray crystal structure of [(CN)₂Th₂Pyz] shows the presence of one thienyl ring positioned orthogonal to the rest of the molecule, with the two vicinal thienyl rings lying orthogonal to each other in a rare arrangement. NMR studies of [(CN)₂Th₂Pyz] in the solid state and in solutions of dimethylformamide or dimethyl sulfoxide confirm a nonequivalence of the thienyl rings in the solid state and also in solution. EXAFS results indicate that two distinct Pd^II coordination sites are formed at the di(2-thienyl)pyrazino moiety of [(CN)₂Th₂Pyz(PdCl₂)₂]路H₂O, with identical Pd鈥揘_pyz (2.03(3) 脜) and Pd鈥揅l (2.36(3) 脜) bond lengths but with different Pd鈥揝1 (2.25(4) 脜) and Pd鈥揝2 (3.21(5) 脜) bond distances in an overall asymmetric molecular framework. Density functional theory (DFT) and time-dependent DFT (TDDFT) theoretical studies also provide information about the structure and spectral behavior of the precursor and its metalated Pd^II derivative. ¹H/¹³C NMR and UV鈥搗isible spectral measurements were also carried out on two heteropentametallic porphyrazine macrocycles which were prepared by a reaction of PdCl₂ with [Th₈TPyzPzM] where Th₈TPyzPz = tetrakis-2,3-[5,6-di-(2-thienyl)-pyrazino]porphyrazinato dianion and M = Mg^II(H₂O) or Zn^II. Spectroscopic data on the newly synthesized [(PdCl₂)₄Th₈TPyzPzM] compounds suggest that the binding of PdCl₂ involves coordination sites of the type S_2(th)PdCl₂ with the two thienyl rings of each di(2-thienyl)pyrazino fragment bound to Pd^II in an equivalent manner (鈥渢h-th鈥?coordination). This is similar to what was found for the corresponding octapyridinated analogues (鈥減y-py鈥?coordination).