Valence Fluctionality of Trinuclear Ruthenium Complex Dimers

配体桥联六钌簇合物Ru_3（μ_3-O）混合价态内的分子内电子转移（mu-CH_3CO_2）_6（CO）（L）（mu-L'）Ru_3（mu_3-O）（μ-CH_3CO_2）_6（CO）（L）（L ′ = 1，4-吡嗪; L = 4-二甲基氨基吡啶（1）、吡啶（2）、4-氰基吡啶（3）或L ′ = 4，4 ′-联吡啶; L = 4-二甲氨基吡啶（4）、吡啶（5）、4-氰基吡啶（6）。在1 - 5的氧化还原化学中，通过循环伏安法可以明显看出两个离散的和可逆的单电子还原，并且簇间电荷转移络合物被很好地定义。分裂的还原波，E，是有关<AB>的三钌簇之间的电子耦合H_，并从80 mV的5到440 mV的1。在6的情况下，还原波的分裂E &lt; 50 mV，簇间电荷转移络合物未定义。1 - 3的混合价态也在12，100 cm^（1）至10，80 cm^（1）区域显示出价间电荷转移（ICT）带<-1> ...更多信息 0 cm^<-1>（3），其提供了在<AB>2180 cm^<-1>（1）至1310 cm^<-1>（3）范围内的H_的光谱估计。发现电子耦合H_的大小<AB>强烈影响n（CO）区1 - 6单还原（-1）混合价态的红外光谱。在相对弱的电子耦合（4 - 6）的情况下，两个v（CO）带清楚地解决。在强电子耦合（1 - 3）的情况下，这些带加宽到一个单一的v（CO）吸收带。这些数据允许通过模拟动力学效应（Bloch型方程）对在9 × 10^ s^、5 × 10 ^ s^和ca下的v（CO）吸收带形的影响来估计在1、2和3的混合价态中电子转移的速率常数kappa_c<11><-1><11><-1>。1 x 10^<11>s <-1>^。偶联较弱的4，4 '-联吡啶桥连配合物4 - 6在-1混合价态下表现出IR线形，其不受电子转移动力学的强烈影响。4的-1混合价态的速率常数接近通过这种方法可以估计的下限，在1 x 10^<10>和1 x 10^<11>s^之间<-1>。少

lntramolecular electron transfers within the mixed valence states of the ligand bridged hexaruthenium clusters Ru_3(mu_3-O)(mu-CH_3CO_2)_6(CO)(L)(mu-L')Ru_3(mu_3-O)(mu-CH_3CO_2)_6(CO)(L)(L' = 1,4-pyrazine ; L = 4-dimethyl-aminopyridine (1), pyridine (2), 4-cyanopyridine (3), or L' = 4,4'-bipyridine ; L = 4-dimethyl-aminopyridine (4), pyridine (5), 4-cyanopyridine (6) were examined. Two discrete and reversible single electron reductions are evident by cyclic voltammetry in the redox chemistry of 1 - 5, and the inter-cluster charge transfer complexes are well defined. The splitting of the reduction waves, E, is related to the electronic coupling H_<AB> between the triruthenium clusters, and varies from 80 mV for 5 to 440 mV for 1. In the case of 6, the splitting of the reduction waves, E, is < 50 mV and the inter-cluster charge transfer complex is not defined. The mixed valence states of 1 - 3 also exhibit intervalence charge transfer (ICT) bands in the region 12,100 cm^<-1> (1) to 10,80 … More 0 cm^<-1> (3) which provide spectroscopic estimates of H_<AB> in the range 2180 cm^<-1> (1) to 1310 cm^<-1> (3). The magnitude of the electronic coupling H_<AB> is found to strongly influence the IR spectra of the singly reduced (-1) mixed valence states of 1 - 6 in the n(CO) region. In the case of relatively weak electronic coupling (4 - 6), two v(CO) bands are clearly resolved. In the cases of strong electronic coupling (1 - 3), these bands broaden to a single v(CO) absorption band. These data allow the rate constants, kappa_c, for electron transfer in the mixed valence states of 1, 2, and 3 to be estimated by simulating dynamical effects (Bloch type equations) on v(CO) absorption bandshape at 9 x 10^<11> s^<-1>, 5 x l0^<11> s^<-1>, and ca . 1 x 10^<11> s^<-1>, respectively. The less strongly coupled 4,4'-bipyridine bridged complexes 4 - 6 exhibit IR lineshapes in the -1 mixed valence states that are not as strongly affected by electron transfer dynamics. The rate constant for the -1 mixed valence state of 4 is close to the lower limit that can be estimated by this approach, between 1 x 10^<10> and 1 x 10^<11> s^<-1>. Less