Synthesis and Characterization of Ruthenium(II)-Pyridylamine Complexes with Catechol Pendants as Metal Binding Sites
Synthesis and Characterization of Ruthenium(II)-Pyridylamine Complexes with Catechol Pendants as Metal Binding Sites
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DOI：
10.1021/ic902070q
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发表时间：
2010-04-19
影响因子：
4.6
通讯作者：
Fukuzumi, Shunichi
中科院分区：
文献类型：
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作者：
Kojima, Takahiko;Hirasa, Norihisa;Fukuzumi, Shunichi
合成了一种新型的三（2-吡啶甲基）胺（TPA）衍生物，其两个邻苯二酚部分通过酰胺键连接在两个吡啶基的6位上。配体N，N-二[6-{3，4-二氧杂环己基}（二羟基）苯甲酰胺}-2-吡啶基-甲基]-N-（2-吡啶基甲基）胺（Cat（2）-TPA; L2）及其前体N，N-双[6-{3，4-双（苄氧基）-苯甲酰胺}-2-吡啶基甲基]-N-（2-吡啶基甲基）-胺（（Bn（2）Cat）（2）-TPA; L1）分别形成稳定的钌（II）配合物[RuCl（L2）]PF（6）（2）和[RuCl（L1）]PF（6）（1）。[RuCl（L_2）]Cl（2 ′）的晶体结构用X射线晶体学测定，显示出一个邻苯二酚部分取向的两种异构体。在配合物2中，承载儿茶酚的配体作为五齿配体，涉及除了四齿TPA部分和两个无金属儿茶酚部分作为金属结合位点之外的酰胺氧原子之一的配位。L2的配位导致两种儿茶酚的预组织以使它们会聚以进行分子内π-π相互作用。2在DMSO-d（6）中的（1）H NMR光谱显示溶液中仅存在一种异构体。这种选择性的形成可以归因于邻苯二酚部分的羟基之间形成分子内氢键网络，如通过X-射线分析所建议的。这种分子内氢键可以区分的邻苯二酚部分的羟基的pK（a）值分为三种，如所示的光谱滴定与四甲基氢氧化铵（TMAOH）在DMF中。2与其他金属离子的络合作用也进行了研究。2与[Cu（NO（3））（2）（TMEDA）]（TMEDA = N，N，N '，N'-四甲基乙二胺）在甲醇中的反应使我们能够观察到双核配合物[RuCl（L2（2-））{Cu（TMEDA）}]PF（6）（3）的选择性形成，其结构通过ESI-MS，UV-vis和ESR光谱进行表征。在甲醇溶液中的ESR谱表明，Cu（II）-TMEDA单元与邻苯二酚的配位不同于传统的kappa（2）-O，O '：eta（2）-配位，表现出一种新的桥联配位模式，即双kappa（1）-O：eta（1）-配位，形成双核Ru（II）-Cu（II）配合物.
A novel tris(2-pyridylmethyl)amine (TPA) derivate having two catechol moieties linked by amide linkages at the 6-positions of two pyridyl groups was synthesized. The ligand, N,N-bis[6-{3,4-(dihydroxy)benzamide}-2-pyridyl-methyl]-N-(2-pyridylmethyl)amine (Cat(2)-TPA; L2), and its precursor, N,N-bis[6-{3,4-bis(benzyloxy)-benzamide}-2-pyridylmethyl]-N-(2-pyridylmethyl)-amine ((Bn(2)Cat)(2)-TPA; L1), formed stable ruthenium(II) complexes, [RuCl(L2)]PF(6) (2) and [RuCl(L1)]PF(6) (1), respectively. The crystal structure of [RuCl(L2)]Cl (2') was determined by X-ray crystallography to show two isomers in terms of the orientation of one catechol moiety. In complex 2, the ligand bearing catechols acts as a pentadentate ligand involving coordination of one of the amide oxygen atoms in addition to that of the tetradentate TPA moiety and two metal-free catechol moieties as metal-binding sites. The coordination of L2 results in the preorganization of the two catechols to converge them to undergo intramolecular pi-pi interactions. The (1)H NMR spectrum of 2 in DMSO-d(6) revealed that only one isomer was present in the solution. This selective formation could be ascribed to the formation of an intramolecular hydrogen-bonding network among the hydroxyl groups of the catechol moieties, as suggested by X-ray analysis. This intramolecular hydrogen bonding could differentiate the pK(a) values of the hydroxy groups of the catechol moieties into three kinds, as indicated by spectroscopic titration with tetramethylammonium hydroxide (TMAOH) in DMF. The complexation of 2 with other metal ions was also examined. The reaction of 2 with [Cu(NO(3))(2)(TMEDA)] (TMEDA = N,N,N',N'-tetramethylethylenediamine) in methanol allowed us to observe the selective formation of a binuclear complex, [RuCl(L2(2-)){Cu(TMEDA)}]PF(6) (3), which was characterized by ESI-MS, UV-vis, and ESR spectroscopies. Its ESR spectrum in methanol suggested that the coordination of the Cu(II)-TMEDA unit to the converged catechol moieties would be different from conventional kappa(2)-O,O':eta(2)-coordination: it exhibits a novel bridging coordination mode, bis-kappa(1)-O:eta(1)-coordination, to form the binuclear Ru(II)-Cu(II) complex.