A novel series of rhenium-bipyrimidine complexes:: synthesis, crystal structure and electrochemical properties
A novel series of rhenium-bipyrimidine complexes:: synthesis, crystal structure and electrochemical properties
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DOI：
10.1039/b615136a
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发表时间：
2007-01-01
影响因子：
4
通讯作者：
Faus, Juan
中科院分区：
文献类型：
--
作者：
Chiozzone, Raul;Gonzalez, Ricardo;Faus, Juan
合成了四种新型铼配合物[ReCl4(bpym)](1)、[ReBr4(bpym)](2)、PPh4[ReCl4(bpym)](3)和NBu4[ReBr4(bpym)] (4) （bpym = 2,2'-联嘧啶，PPh4 =四苯基磷酸阳离子和NBu4 =四丁基铵阳离子），并通过单晶X射线衍射测定了它们的晶体结构。1和2的结构由[ReX4(bpym)]分子通过范德华力结合在一起。在这两种配合物中，Re（IV）的中心原子在扭曲的八面体环境中被四个卤化物阴离子和两个双齿配体的氮原子所包围。3和4的结构由[ReX4(bpym)]-阴离子和PPh4+(3)或NBu4+(4)阳离子组成。Re（III）金属离子的配位球分别与1和2相同。然而，Re - X键较长，而Re - n键较短。这一事实表明，bpym配体与Re（III）形成的键比与Re（IV）形成的键更强，从而稳定了低氧化态。[ReX4(bpym)]配合物很容易通过化学和电化学还原成相应的[ReX4(bpym)]（-）阴离子。伏安研究表明，电子转移是一个可逆过程，其形式氧化还原电位为+ 0.19 V(1)和+ 0.32 V(2)，相对于NHE，乙腈为溶剂。
Four novel rhenium complexes of formula [ ReCl4( bpym)] (1), [ ReBr4( bpym)] ( 2) PPh4[ ReCl4( bpym)] ( 3) and NBu4[ReBr4(bpym)] ( 4) ( bpym= 2,2'- bipyrimidine, PPh4 = tetraphenylphosphonium cation and NBu4 = tetrabutylammonium cation), have been synthesized and their crystal structures determined by single-crystal X- ray diffraction. The structures of 1 and 2 consist of [ ReX4( bpym)] molecules held together by van der Waals forces. In both complexes the Re(IV) central atom is surrounded by four halide anions and two nitrogen atoms of a bpym bidentate ligand in a distorted octahedral environment. The structures of 3 and 4 consist of [ ReX4( bpym)]- anions and PPh4+ ( 3) or NBu4+ ( 4) cations. The coordination sphere of the Re(III) metal ion is the same as in 1 and 2, respectively. However, whereas the Re - X bonds are longer the Re -N bonds are shorter than in 1 and 2. This fact reveals that the bpym ligand forms a stronger bond with Re( III) than with Re( IV) resulting in a stabilisation of the lower oxidation state. [ ReX4( bpym)] complexes are easily reduced, chemically and electrochemically, to the corresponding [ ReX4( bpym)](-) anions. A voltammetric study shows that the electron transference is a reversible process characterized by formal redox potentials of + 0.19 V ( 1) and + 0.32 V ( 2) vs. NHE, in acetonitrile as solvent.