Synthesis of paramagnetic tetranuclear rhodium and iridium complexes with the 2,6-pyridinedithiolate ligand. Redox-induced degradation to diamagnetic triiridium compounds.
Synthesis of paramagnetic tetranuclear rhodium and iridium complexes with the 2,6-pyridinedithiolate ligand. Redox-induced degradation to diamagnetic triiridium compounds.
复制标题
具有 2,6-二硫代吡啶配体的顺磁性四核铑和铱配合物的合成。
DOI：
10.1021/ic001349q
复制
发表时间：
2001
影响因子：
4.6
通讯作者：
L. Oro
中科院分区：
文献类型：
--
作者：
M. A. Casado;J. Pérez‐Torrente;J. López;M. Ciriano;P. Alonso;F. Lahoz;L. Oro
四核配合物[M4(mu-PyS2)2（二烯烃）4][PyS2 = 2,6-吡啶二硫酯；M = Rh，二烯烃= cod（1,5-环二烯）(1),tfbb（四氟苯并[5,6]双环[2.2.2]八-2,5,7-三烯）(2)；M = Ir，二烯烃= cod (3), tfbb(4)]在化学试剂可及的电位下，在二氯甲烷中的铂盘电极上表现出两次单电子氧化。铑四核配合物被温和的单电子氧化剂(如[Cp2Fe]（+）或[N(C6H4Br-4)3]（+）选择性氧化为单离子配合物[Rh4(mu_pys2)2（二烯烃）4](+)(1)(+),2(+))，并分离为PF6(-), BF4（-）和ClO4（-）盐。在与铑络合物1和2的反应中，银盐表现为非无害的单电子氧化剂，因为它们产生难溶的配位聚合物。3与1摩尔当量的AgBF4反应得到配合物[Ir4(mu-PyS2)2(cod)4](+)(3)（+）作为四氟硼酸盐，但[Ir4(mu-PyS2)2(tfbb)4](4)与AgBF4化学氧化不能分离出相应的配合物4（+）。用2摩尔等量的普通银盐氧化3和4，导致配合物破碎，得到抗磁性的氚离子[Ir3(mu-PyS2)2（二烯烃）3]（+）。用x射线衍射方法测定了[Ir3(mu-PyS2)2(cod)3]BF4的分子结构，发现三个金属原子呈角状排列。这两种2,6-吡啶二硫酯三齿配体都在伪八面体环境中桥接两个金属-金属键d(7)中心和一个d(8)方形平面铱中心。对63个电子混价顺磁四核配合物的EPR谱的解释表明，未配对电子在配合物1(+)-3（+）中的两个金属原子上离域。
The tetranuclear complexes [M4(mu-PyS2)2(diolefin)4] [PyS2 = 2,6-pyridinedithiolate; M = Rh, diolefin = cod (1,5-cyclooctadiene) (1), tfbb (tetrafluorobenzo[5,6]bicyclo[2.2.2]octa-2,5,7-triene) (2); M = Ir, diolefin = cod (3), tfbb (4)] exhibit two one-electron oxidations at a platinum disk electrode in dichloromethane at potentials accessible by chemical reagents. The rhodium tetranuclear complexes were selectively oxidized to the monocationic complexes [Rh4(mu-PyS2)2(diolefin)4](+) (1(+), 2(+)) by mild one-electron oxidants such as [Cp2Fe](+) or [N(C6H4Br-4)3](+) and isolated as the PF6(-), BF4(-), and ClO4(-) salts. Silver salts behave as noninnocent one-electron oxidants for the reactions with the rhodium complexes 1 and 2 since they give sparingly soluble coordination polymers. The complex [Ir4(mu-PyS2)2(cod)4](+) (3(+)) was obtained as the tetrafluoroborate salt by reaction of 3 with 1 molar equiv of AgBF4, but the related complex 4(+) could not be isolated from the chemical oxidation of [Ir4(mu-PyS2)2(tfbb)4] (4) with AgBF4. Oxidation of 3 and 4 with 2 molar equiv of common silver salts resulted in the fragmentation of the complexes to give the diamagnetic triiridium cations [Ir3(mu-PyS2)2(diolefin)3](+). The molecular structure of [Ir3(mu-PyS2)2(cod)3]BF4, determined by X-ray diffraction methods, showed the three metal atoms within an angular arrangement. Both 2,6-pyridinedithiolate tridentate ligands bridge two metal-metal bonded d(7) centers in pseudo octahedral environments and one d(8) square-planar iridium center. An interpretation of the EPR spectra of the 63-electron mixed-valence paramagnetic tetranuclear complexes suggests that the unpaired electron is delocalized over two of the metal atoms in the complexes 1(+)-3(+).