Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany.
Inorg Chem. 2011 Dec 19;50(24):12747-61. doi: 10.1021/ic2018902. Epub 2011 Nov 15.
A series of novel dinuclear platinum(II) complexes were synthesized containing a mixed nitrogen-sulfur donor bidentate chelate system in which the two platinum centers are connected by an aliphatic chain of variable length. The bidentate chelating ligands were selected to stabilize the complex toward decomposition. The pK(a) values and reactivity of the four synthesized complexes, namely, Pt(2)(S(1),S(4)-bis(2-pyridylmethyl)-1,4-butanedithioether)(OH(2))(4) (4NSpy), Pt(2)(S(1),S(6)-bis(2-pyridylmethyl)-1,6-hexanedithioether)(OH(2))(4) (6NSpy), Pt(2)(S(1),S(8)-bis(2-pyridylmethyl)-1,8-octanedithioether)(OH(2))(4) (8NSpy), and Pt(2)(S(1),S(10)-bis(2-pyridylmethyl)-1,10-decanedithioether)(OH(2))(4) (10NSpy), were investigated. This system is of special interest because only little is known about the substitution behavior of dinuclear platinum complexes that contain a bidentate chelate that forms part of the aliphatic bridging ligand. Moreover, the ligands as well as the dinuclear complexes were examined in terms of their cytotoxic activity, and the 10NSpy complex was found to be active. Spectrophotometric acid-base titrations were performed to determine the pK(a) values of all the coordinated water molecules. The substitution of coordinated water by thiourea was studied under pseudo-first-order conditions as a function of nucleophile concentration, temperature, and pressure, using stopped-flow techniques and UV-vis spectroscopy. The results for the dinuclear complexes were compared to those for the corresponding mononuclear reference complex Pt(methylthiomethylpyridine)(OH(2))(2) (Pt(mtp)), by which the effect of the increasing aliphatic chain length of the bridged complexes could be investigated. The results indicate that there is a clear interaction between the two platinum centers, which becomes weaker as the chain length between the metal centers increases. Furthermore, differences and similarities of the N,S-system were compared to the corresponding dinuclear N,N-system studied previously in our group. In addition, quantum chemical calculations were performed to support the interpretation and discussion of the experimental data.
合成了一系列新型双核铂(II)配合物，其中包含混合氮硫供体双齿螯合体系，两个铂中心通过可变长度的脂肪链连接。双齿螯合配体被选择来稳定配合物以防止分解。四种合成配合物的 pK(a) 值和反应性，即 Pt(2)(S(1),S(4)-双(2-吡啶甲基)-1,4-丁二硫醚)(OH(2))(4) (4NSpy)、Pt(2)(S(1),S(6)-双(2-吡啶甲基)-1,6-己二硫醚)(OH(2))(4) (6NSpy)、Pt(2)(S(1),S(8)-双(2-吡啶甲基)-1,8-辛二硫醚)(OH(2))(4) (8NSpy) 和 Pt(2)(S(1),S(10)-双(2-吡啶甲基)-1,10-癸二硫醚)(OH(2))(4) (10NSpy)，进行了研究。这个系统特别有趣，因为只有很少的关于包含双齿螯合物的双核铂配合物的取代行为的知识，该螯合物形成脂肪桥接配体的一部分。此外，还研究了配体和双核配合物的细胞毒性活性，发现 10NSpy 配合物具有活性。进行了分光光度酸碱滴定以确定所有配位水分子的 pK(a) 值。在准一级条件下，使用停流技术和紫外可见光谱法，研究了硫脲取代配位水的反应，作为亲核试剂浓度、温度和压力的函数。将双核配合物的结果与相应的单核参考配合物 Pt(methylthiomethylpyridine)(OH(2))(2) (Pt(mtp))进行了比较，通过这种比较可以研究桥接配合物中脂肪链长度增加的影响。结果表明，两个铂中心之间存在明显的相互作用，随着金属中心之间链长的增加，相互作用变弱。此外，还比较了 N,S-系统与我们之前在小组中研究的相应双核 N,N-系统的差异和相似之处。此外，还进行了量子化学计算以支持对实验数据的解释和讨论。
