Mialane Pierre, Nivorojkine Alexander, Pratviel Geneviève, Azéma Laurent, Slany Michaela, Godde Frédéric, Simaan Ariane, Banse Frédéric, Kargar-Grisel Taraneh, Bouchoux Guy, Sainton Joelle, Horner Olivier, Guilhem Jean, Tchertanova Lyuba, Meunier Bernard, Girerd Jean-Jacques
Laboratoire de Chimie Inorganique, URA CNRS 420, Institut de Chimie Moléculaire d'Orsay, Université Paris-Sud, 91405 Orsay, France, Institut de Chimie des Substances Naturelles, UPR CNRS 2301, 91198 Gif-sur-Yvette, France, Laboratoire de Chimie de Coordination du CNRS, 31077 Toulouse, France, and Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, 91128 Palaiseau, France.
Inorg Chem. 1999 Mar 22;38(6):1085-1092. doi: 10.1021/ic971059i.
The complexes [L(5)Fe(II)Cl]BPh(4) and L(5)Fe(II)(H(2)O)(2) (L(5) = N,N,N'-tris(2-pyridylmethyl)-N'-methyl-ethane-1,2-diamine) have been isolated. Bernal et al. (Bernal, J.; et al. J. Chem. Soc., Dalton Trans. 1995, 3667-3675) have prepared this ligand and the corresponding complex [L(5)Fe(II)Cl]PF(6). We obtained the structural data of [L(5)Fe(II)Cl]BPh(4) by X-ray diffraction. It crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 17.645(7) Å, b = 16.077(6) Å, c = 13.934(5) Å, V = 3953(3) Å(3), and Z = 4. It presents Fe(II)-N bond lengths close to 2.2 Å, typical of high-spin Fe(II). In solution the L(5)Fe(II)(H(2)O)(2) complex showed a dependence of spin state upon the nature of the solvent. It was high spin in acetone and changed to low spin in acetonitrile. This was detected by UV-vis spectroscopy and by (1)H NMR. Bernal et al. (ibidem) showed that these complexes in the presence of an excess of H(2)O(2) give a purple species, very likely the L(5)Fe(III)(OOH) derivative, with spectroscopic signatures analogous to those of "activated bleomycin". The formation of L(5)Fe(III)(OOH) is confirmed here by electrospray ionization mass spectrometry. We found that a L(5)/Fe system gave single-strand breaks on plasmid DNA in the presence of either a reducing agent (ascorbate) and air or oxidants (H(2)O(2), KHSO(5), MMPP) at 0.1 &mgr;M concentration. The methyl group in L(5) was substituted by a (CH(2))(5)N(CH(3))(3)(+) group in order to get higher affinity with DNA. The corresponding ligand L(5)(+) was used to prepare the complexes [L(5)(+)Fe(II)Cl]Y(2) (Y = BPh(4)(-), PF(6)(-), ClO(4)(-)) and L(5)(+)Fe(II)Br(2). The crystal structure of L(5)(+)Fe(II)Cl(2) was solved. It crystallizes in the monoclinic space group P2(1)/a with a = 14.691(2) Å, b = 13.545(2) Å, c = 17.430(2) Å, beta = 93.43(1) degrees, V = 3462(1) Å(3), and Z = 4. The Fe(II)-ligand distances are similar to those of [L(5)Fe(II)Cl]BPh(4). At the relatively low concentration of 0.01 &mgr;M, L(5)(+)Fe(II)Br promoted DNA breaks. The reaction was not inhibited by hydroxyl radical scavengers. The reaction might involve a nondiffusible oxygen reactive species, either a coordinated hydroperoxide or a high-valent metal-oxo entity.
已分离出配合物[L(5)Fe(II)Cl]BPh(4)和L(5)Fe(II)(H₂O)₂（L(5) = N,N,N'-三(2-吡啶基甲基)-N'-甲基-乙烷-1,2-二胺）。贝尔纳尔等人（贝尔纳尔，J.；等人，《化学学会志，道尔顿汇刊》，1995年，3667 - 3675页）制备了这种配体以及相应的配合物[L(5)Fe(II)Cl]PF₆。我们通过X射线衍射获得了[L(5)Fe(II)Cl]BPh(4)的结构数据。它结晶于正交空间群P2(1)2(1)2(1)，a = 17.645(7) Å，b = 16.077(6) Å，c = 13.934(5) Å，V = 3953(3) ų，Z = 4。它呈现出接近2.2 Å的Fe(II)-N键长，这是高自旋Fe(II)的典型特征。在溶液中，L(5)Fe(II)(H₂O)₂配合物的自旋态取决于溶剂的性质。它在丙酮中为高自旋，在乙腈中转变为低自旋。这通过紫外可见光谱和¹H NMR检测到。贝尔纳尔等人（同前）表明，这些配合物在过量H₂O₂存在下会产生一种紫色物质，很可能是[L(5)Fe(III)(OOH)]²⁺衍生物，其光谱特征与“活化博来霉素”类似。此处通过电喷雾电离质谱法证实了[L(5)Fe(III)(OOH)]²⁺的形成。我们发现，在0.1 μM浓度下，L(5)/Fe体系在存在还原剂（抗坏血酸盐）和空气或氧化剂（H₂O₂、KHSO₅、MMPP）时会使质粒DNA产生单链断裂。L(5)中的甲基被(CH₂)₅N(CH₃)₃⁺基团取代，以获得与DNA更高的亲和力。相应的配体L(5)⁺用于制备配合物[L(5)⁺Fe(II)Cl]Y₂（Y = BPh₄⁻、PF₆⁻、ClO₄⁻）和L(5)⁺Fe(II)Br₂。解析了L(5)⁺Fe(II)Cl₂的晶体结构。它结晶于单斜空间群P2(1)/a，a = 14.691(2) Å，b = 13.545(2) Å，c = 17.430(2) Å，β = 93.43(1)°，V = 3462(1) ų，Z = 4。Fe(II)-配体距离与[L(5)Fe(II)Cl]BPh(4)的相似。在相对低的0.01 μM浓度下，[L(5)⁺Fe(II)Br]²⁺促进DNA断裂。该反应不受羟基自由基清除剂的抑制。该反应可能涉及一种不可扩散的氧反应性物种，要么是配位的氢过氧化物，要么是高价金属-氧实体。
