Department of Inorganic Chemistry, University of Zürich, Switzerland.
J Am Chem Soc. 2010 Mar 10;132(9):3115-27. doi: 10.1021/ja909764x.
The dinuclear tungsten carbyne [X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X] (dppe = 1,2-bis(diphenylphosphino)ethane; X = I (3), Cl (7)) complexes were prepared from the bisacetylide precursor Li(2)[(CO)(3)(dppe)WC(4)W(CO)(3)(dppe)] (2) via oxidative replacement of one CO group at each tungsten center with a halide substituent. The iodide ligand in 3 could be substituted with isothiocyanate or triflate resulting in [X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X] complexes (X = NCS (8), OTf (9)). Substitution of two and all four CO ligands in 3 was achieved via subsequent photolytic or thermal activation with dppe. The "half-substituted" complex [I(CO)(2)(dppe)WC(4)W(dppe)(2)I] (11) allows reversible one-electron oxidation which results in the monocationic species [I(CO)(2)(dppe)WC(4)W(dppe)(2)I][PF(6)] (11[PF(6)]). The "all-dppe substituted" complex [I(dppe)(2)WC(4)W(dppe)(2)I] (10) possesses two reversible redox states leading to the stable monocationic [I(dppe)(2)WC(4)W(dppe)(2)I][PF(6)] (10[PF(6)]) and the dicationic [I(dppe)(2)WC(4)W(dppe)(2)I]PF(6) (10PF(6)) compounds. The complexes 2, 3, [W(CO)(3)(dppe)(C[triple bond]CPh)(I)] (4), [X(CO)(2)(dppe)W[triple bond]C-C(Me)=C(Me)-C[triple bond]W(dppe)(CO)(2)X] (X = I (5), Cl (6)), 7, 8, 10, 11 and 11[PF(6)] were characterized by single crystal X-ray diffraction. The electronic properties of complexes 10, 10[PF(6)], 10PF(6), as well as of compounds 11 and 11[PF(6)], were investigated using cyclic voltammetry (CV), EPR, IR, near-IR spectroscopy, and magnetization measurements. These studies showed that the [W][triple bond]C-C[triple bond]C-C[triple bond][W] canonical form of the bridged system with strong tungsten-carbon interaction contributes significantly to the electronic coupling in the mixed-valent species 10[PF(6)] (comproportionation constant K(c) = 7.5 x 10(4)) and to the strong antiferromagnetic coupling in the dicationic complex 10PF(6) (exchange integral J = -167 cm(-1)). In addition, the rate for electron transfer between the tungsten centers in 10[PF(6)] was evaluated by near-IR and IR studies.
双核钨卡宾X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X乙烷; X=I(3), Cl(7))配合物由双炔基前体 Li(2)[(CO)(3)(dppe)WC(4)W(CO)(3)(dppe)] (2)通过每个钨中心的一个 CO 基团与卤化物取代基的氧化取代反应制备。3 中的碘配体可以被异硫氰酸根或三氟甲磺酸根取代，得到[X(CO)(2)(dppe)WC(4)W(dppe)(CO)(2)X]配合物(X=NCS(8), OTf(9))。通过随后的光解或热解用 dppe 取代 3 中的两个和所有四个 CO 配体。"半取代"配合物I(CO)(2)(dppe)WC(4)W(dppe)(2)I允许可逆的单电子氧化，导致单价物种[I(CO)(2)(dppe)WC(4)W(dppe)(2)I]PF(6)。"全 dppe 取代"配合物I(dppe)(2)WC(4)W(dppe)(2)I具有两个可逆的氧化还原态，导致稳定的单价[I(dppe)(2)WC(4)W(dppe)(2)I]PF(6)和二价[I(dppe)(2)WC(4)W(dppe)(2)I]PF(6) (10PF(6))化合物。配合物 2、3、[W(CO)(3)(dppe)(C[三重键]CPh)(I)] (4)、X(CO)(2)(dppe)W[三重键]C-C(Me)=C(Me)-C[三重键]W(dppe)(CO)(2)X, Cl(6))、7、8、10、11 和 11[PF(6)]通过单晶 X 射线衍射进行了表征。通过循环伏安法(CV)、EPR、IR、近红外光谱和磁化率测量研究了配合物 10、10[PF(6)]、10PF(6)以及化合物 11 和 11[PF(6)]的电子性质。这些研究表明，桥接体系中[W][三重键]C-C[三重键]C-C[三重键][W]的典型形式与强的钨-碳相互作用显著贡献于混合价物种 10[PF(6)](比例常数 K(c)=7.5 x 10(4))和二价配合物 10PF(6)中的强反铁磁耦合(J=-167 cm(-1))。此外，通过近红外和红外研究评估了 10[PF(6)]中钨中心之间电子转移的速率。
