Asymmetrical diruthenium complex bridged by a redox-active ligand.
Asymmetrical diruthenium complex bridged by a redox-active ligand.
复制标题
DOI：
10.1021/ic201975h
复制
发表时间：
2012-01
影响因子：
4.6
通讯作者：
A. Das;T. Scherer;A. Chowdhury;S. Mobin;W. Kaim;G. K. Lahiri
中科院分区：
文献类型：
--
作者：
A. Das;T. Scherer;A. Chowdhury;S. Mobin;W. Kaim;G. K. Lahiri
以单核前体[Ru（acac）（2）（abpy）]和[Ru（Cym）Cl（2）]（2）为原料，合成了不对称双核配合物[（acac）（2）Ru_1（μ-abpy）Ru_2（Cym）Cl]PF（6）（[2]PF（6）），其中acac（-）=乙酰丙酮基= 2，4-戊二酮基，abpy = 2，2 ′-偶氮二吡啶，Cym =对异丙基-4-甲基苯. X射线晶体结构分析表明2（+）的氧化态结构为[（acac）（2）Ru 1（III）（μ-abpy（·-））Ru 2（II）（Cym）Cl]（+），其中一个Ru（III）中心与自由基-阴离子桥连配体（abpy（·-））之间存在反铁磁耦合，基于N-N距离为1.352（3）<$。作为适当的参考，新合成的单核[（abpy）Ru（II）（Cym）Cl]PF（6）（[1]PF（6））具有未还原的N <$N双键，d（NN）= 1.269（4）<$，对称的双核[（acac）（2）Ru（2.5）（μ-abpy（·-））Ru（2.5）（acac）（2）]的d（NN）= 1.372（4）π（外消旋体）支持了2（+）的上述不对称混合价构型。可逆的单电子氧化导致二价阳离子2（2+），具有很大程度上以金属为中心的自旋（EPR：g（1）= 2.207，g（2）= 2.155，和g（3）= 1.929），和在1700 nm处的弱的价间电荷转移吸收，如光谱电化学所观察到的。这些结果支持2（2+）为[（acac）（2）Ru 1（III）（μ-abpy（0））Ru 2（II）（Cym）Cl]（2+）的描述。密度泛函理论（DFT）计算表明，[2]PF（6）的第一次还原也涉及桥连配体，导致[（acac）（2）Ru 1（III）（μ-abpy（2-））Ru 2（II）（Cym）Cl]（2）。实验上，2（+）的第一次还原不是完全可逆的，有证据表明氯离子损失形成[（acac）（2）Ru 1（μ-abpy）Ru 2（Cym）]（+）（2a（+）; g（1）= 2.454，g（2）= 2.032，g（3）= 1.947）。进一步还原产生[（acac）（2）Ru 1（II）]（μ-abpy（2-））Ru 2（II）（Cym）]（2a），形成[（acac）（2）Ru 1（II）（μ-abpy（2-））Ru 2（I）（Cym）]（-）/[（acac）（2）Ru（II）（μ-abpy（·-））Ru（0）（Cym）]（-）（2a（-））在又一个单电子步骤中（g（1）= 2.052，g（2）= 2.008，和g（3）= 1.936）。每个氧化还原态的主要电子跃迁已被指定的时间依赖性DFT计算。
The asymmetrical dinuclear complex [(acac)(2)Ru1(μ-abpy)Ru2(Cym)Cl]PF(6) ([2]PF(6)), with acac(-) = acetylacetonato = 2,4-pentanedionato, abpy = 2,2'-azobis(pyridine), and Cym = p-cymene = 1-isopropyl-4-methylbenzene, has been obtained from the mononuclear precursors [Ru(acac)(2)(abpy)] and [Ru(Cym)Cl(2)](2). X-ray crystal structure analysis suggests the oxidation state formulation [(acac)(2)Ru1(III)(μ-abpy(•-))Ru2(II)(Cym)Cl](+) for 2(+), with antiferromagnetic coupling between one Ru(III) center and the radical-anion bridging ligand (abpy(•-)), based on the N-N distance of 1.352(3) Å. As appropriate references, the newly synthesized mononuclear [(abpy)Ru(II)(Cym)Cl]PF(6) ([1]PF(6)) with an unreduced N═N double bond at d(NN) = 1.269(4) Å and the symmetrical dinuclear [(acac)(2)Ru(2.5)(μ-abpy(•-))Ru(2.5)(acac)(2)] with d(NN) = 1.372(4) Å (rac isomer) support the above assignment for 2(+) as an asymmetrical mixed-valent configuration bridged by a radical ligand. Reversible one-electron oxidation leads to a dication, 2(2+), with largely metal-centered spin (EPR: g(1) = 2.207, g(2) = 2.155, and g(3) = 1.929), and a weak intervalence charge-transfer absorption at 1700 nm, as observed by spectroelectrochemistry. These results support a description of 2(2+) as [(acac)(2)Ru1(III)(μ-abpy(0))Ru2(II)(Cym)Cl](2+). Density functional theory (DFT) calculations suggest that the first reduction of [2]PF(6) also involves the bridging ligand, leading to [(acac)(2)Ru1(III)(μ-abpy(2-))Ru2(II)(Cym)Cl] (2). Experimentally, the first reduction of 2(+) is not fully reversible, with evidence for the loss of chloride to form [(acac)(2)Ru1(μ-abpy)Ru2(Cym)](+) (2a(+); g(1) = 2.454, g(2) = 2.032, and g(3) = 1.947). Further reduction produces [(acac)(2)Ru1(II)(μ-abpy(2-))Ru2(II)(Cym)] (2a), which forms [(acac)(2)Ru1(II)(μ-abpy(2-))Ru2(I)(Cym)](-)/[(acac)(2)Ru(II)(μ-abpy(•-))Ru(0)(Cym)](-) (2a(-)) in yet another one-electron step (g(1) = 2.052, g(2) = 2.008, and g(3) = 1.936). The major electronic transitions for each redox state have been assigned by time-dependent DFT calculations.