Barral M Carmen, Gallo Teresa, Herrero Santiago, Jiménez-Aparicio Reyes, Torres M Rosario, Urbanos Francisco A
Departamento de Química Inorganica and Centro de Asistencia a la Investigación de Rayos X, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain.
Inorg Chem. 2006 May 1;45(9):3639-47. doi: 10.1021/ic052174t.
The reaction of Ru2Cl(O2CMe)(DPhF)3 (DPhF = N,N'-diphenylformamidinate) with mono- and polycarboxylic acids gives a clean substitution of the acetate ligand, leading to the formation of complexes Ru2Cl(O2CC6H5)(DPhF)3 (1), Ru2Cl(O2CC6H4-p-CN)(DPhF)3 (2), [Ru2Cl(DPhF)3(H2O)]2(O2C)2 (3), [Ru2Cl(DPhF)3]2[C6H4-p-(CO2)2] (4), and [Ru2Cl(DPhF)3]3[C6H3-1,3,5-(CO2)3] (5). The preparation of [Ru2(NCS)(DPhF)3]3[C6H3-1,3,5-(CO2)3] (6) and {[Ru2(DPhF)3(H2O)]3[C6H3-1,3,5-(CO2)3]}(SO3CF3)3 (7) from 5 is also described. All complexes are characterized by elemental analysis, IR and electronic spectroscopy, mass spectrometry, cyclic voltammetry, and variable-temperature magnetic measurements. The crystal structure determinations of complexes 2.0.5THF and 3.THF.4H2O (THF = tetrahydrofuran) are reported. The reactions carried out demonstrate the high chemical stability of the fragment [Ru2(DPhF)3]2+, which is preserved in all tested experimental conditions. The stability of this fragment is also corroborated by the mass spectra. Electrochemical measurements reveal in all complexes one redox process due to the equilibrium Ru2(5+) <--> Ru2(6+). In the polynuclear complex 7, some additional oxidation processes are also observed that have been ascribed to the presence of two types of dimetallic units rather than two consecutive reversible oxidations. The magnetic behavior toward temperature for complexes 1-7 from 300 to 2 K is analyzed. Complexes 1-7 show low values of antiferromagnetic coupling in accordance with the molecular nature in 1 and 2 and the absence of important antiferromagnetic interaction through the carboxylate bridging ligands in 3-7, respectively. In addition, the magnetic properties of complex 7 do not correspond to any magnetic behavior described for diruthenium(II,III) complexes. The experimental data of compound 7 are simulated considering a physical mixture of S = 1/2 and 3/2 spin states. This magnetic study demonstrates the high sensitivity of the electronic configuration of the unit [Ru2(DPhF)3]2+ to small changes in the nature of the axial ligands. Finally, the energy gap between the pi and delta orbitals in these types of compounds allows the tentative assignment of the transition pi --> delta.
Ru2Cl(O2CMe)(DPhF)3（DPhF = N,N'-二苯基甲脒）与一元羧酸和多元羧酸反应时，乙酸根配体会被完全取代，从而形成配合物Ru2Cl(O2CC6H5)(DPhF)3（1）、Ru2Cl(O2CC6H4-p-CN)(DPhF)3（2）、[Ru2Cl(DPhF)3(H2O)]2(O2C)2（3）、[Ru2Cl(DPhF)3]2[C6H4-p-(CO2)2]（4）和[Ru2Cl(DPhF)3]3[C6H3-1,3,5-(CO2)3]（5）。文中还描述了由5制备[Ru2(NCS)(DPhF)3]3[C6H3-1,3,5-(CO2)3]（6）和{[Ru2(DPhF)3(H2O)]3[C6H3-1,3,5-(CO2)3]}(SO3CF3)3（7）的过程。所有配合物均通过元素分析、红外光谱和电子光谱、质谱、循环伏安法以及变温磁性测量进行表征。报道了配合物2·0.5THF和3·THF·4H2O（THF = 四氢呋喃）的晶体结构测定结果。所进行的反应表明片段[Ru2(DPhF)3]2+具有很高的化学稳定性，在所有测试的实验条件下均能保持稳定。质谱也证实了该片段的稳定性。电化学测量表明，所有配合物中均存在一个由于Ru2(5+)⇌Ru2(6+)平衡引起的氧化还原过程。在多核配合物7中，还观察到一些额外的氧化过程，这归因于存在两种类型的双金属单元，而非两个连续的可逆氧化过程。分析了配合物1 - 7在300至2 K温度范围内的磁行为。配合物1 - 7分别根据1和2中的分子性质以及3 - 7中通过羧酸根桥连配体不存在重要反铁磁相互作用的情况，显示出较低的反铁磁耦合值。此外，配合物7的磁性性质不符合任何关于二钌(II,III)配合物所描述的磁行为。考虑S = 1/2和3/2自旋态的物理混合物对化合物7的实验数据进行了模拟。该磁性研究表明单元[Ru2(DPhF)3]2+的电子构型对轴向配体性质的微小变化具有高度敏感性。最后，这些类型化合物中π和δ轨道之间的能隙使得可以初步确定π→δ跃迁。
