Longato Bruno, Montagner Diego, Zangrando Ennio
Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131. Padova, Italy.
Dalton Trans. 2009 Apr 7(13):2400-5. doi: 10.1039/b818514j. Epub 2009 Feb 12.
The mixed nucleobases complexes cis-[L(2)Pt{1-MeTy(-H)}(1-MeCy,N(3))]NO(3) (L = PPh(3), ; PMePh(2), ), containing the N(3)-deprotonated 1-methylthymine (1-MeTy(-H)) and the neutral 1-methylcytosine (1-MeCy) have been prepared and characterised. The compounds were obtained by reacting the hydroxo complexes cis-L(2)Pt(mu-OH)(NO(3))(2) with 1-methylthymine (1-MeTy), followed by the addition of 1 equivalent of 1-MeCy. In solution of DMSO, DMF or chlorinated solvents, converts quantitatively into the isomer cis-[L(2)Pt{1-MeTy(-H)}(1-MeCy,N(4))]NO(3) () containing the tautomeric form of the cytosine stabilized through the coordination at the N(4) atom, as shown by single-crystal X-ray analysis. The structural determination of shows the presence in the unit cell of two crystallographic independent complexes having similar conformation, with a different orientation of the two nucleobases (head-head and head-tail) according to the presence of both isomers in solution. Complex , having the less hindered PMePh(2) ligands, in DMSO solution, contains the tautomeric forms of the cytosine in equilibrium and the migration of the metal from the N(3) to N(4) site occurs only to a minor extent.
已制备并表征了含有N(3)-去质子化的1-甲基胸腺嘧啶(1-MeTy(-H))和中性1-甲基胞嘧啶(1-MeCy)的混合核碱基配合物顺式-[L(2)Pt{1-MeTy(-H)}(1-MeCy,N(3))]NO(3)（L = PPh(3)、PMePh(2)）。这些化合物是通过使羟基配合物顺式-L(2)Pt(μ-OH)(NO(3))(2)与1-甲基胸腺嘧啶(1-MeTy)反应，然后加入1当量的1-MeCy得到的。在二甲基亚砜、二甲基甲酰胺或氯化溶剂溶液中，通过单晶X射线分析表明，定量转化为含有通过N(4)原子配位稳定的胞嘧啶互变异构形式的异构体顺式-[L(2)Pt{1-MeTy(-H)}(1-MeCy,N(4))]NO(3)。的结构测定表明，在晶胞中存在两个具有相似构象的晶体学独立配合物，根据溶液中两种异构体的存在，两个核碱基具有不同的取向（头对头和头对尾）。配合物具有位阻较小的PMePh(2)配体，在二甲基亚砜溶液中，含有处于平衡状态的胞嘧啶互变异构形式，并且金属从N(3)位点迁移到N(4)位点仅在较小程度上发生。
