Departamento de Química Inorgánica, Orgánica y Bioquímica, Universidad de Castilla-La Mancha, Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL), Facultad de Ciencias del Medio Ambiente, Avd. Carlos III, s/n, 45071 Toledo, Spain.
Dalton Trans. 2018 Nov 21;47(43):15391-15398. doi: 10.1039/c8dt02641f. Epub 2018 Oct 11.
The titanium complex [TiCp*(thiosal)(thiosalH)] (1) has been synthesised by reaction of [TiCpMe], Cp = η-CMe, with thiosalicylic acid (Hthiosal). Complex 1 reacts with [M(μ-OH)(COD)] (M = Rh, Ir) to yield the corresponding early-late heterobimetallic complexes [TiCp*(thiosal)M(COD)] (M = Rh (2); Ir (3)). Carbon monoxide replaces the COD ligand in 2 and 3 leading to the respective dicarbonyl complexes [TiCp*(thiosal)M(CO)] (M = Rh (4); Ir (5)). Compound 4 reacts with PPh to yield the monocarbonyl derivative [TiCp*(thiosal)Rh(CO)(PPh)] (6). The reaction of compound 1 with LiBu yields the tetrametallic complex [{TiCp*(thiosal)Li}(THF)(HO)] (7). Compound 7 reacts with [RuCpCl(COD)] yielding the heterometallic complex [TiCp(thiosal)RuCp*] (8). The molecular structures of compounds 4, 5 and 7 have been studied by X-ray diffraction. From cyclic voltammetric (CV) and square wave voltammetric (SWV) experiments, we observed that attachment of the titanium moiety of precursor 1 to a late transition metal moiety through the sulfur atoms has a significant influence on the reduction behaviour of the Ti(iv) metal centre. Thus, monometallic 1 exhibits an irreversible reduction process at -1.15 V vs. SCE, whereas the CVs of heterobimetallic compounds 2-6 are characterized by the reversible or quasi-reversible one-electron reduction of the Ti(iv)/Ti(iii) system, suggesting a significant stabilization of the Ti(iii) reduced species. Likewise, substitution of the M(COD) diolefin fragment in 2 and 3 by the M(CO) carbonyl-containing moiety (in compounds 4 and 5) leads to a significant anodic shift in the titanium E reduction redox potentials.
[TiCp*（硫代水杨酸）（硫代水杨酸 H）]（1）的钛配合物通过[TiCpMe]，Cp=η-CMe，与硫代水杨酸（Hthiosal）反应合成。配合物 1 与[M（μ-OH）（COD）]（M=Rh，Ir）反应生成相应的早晚期杂金属配合物[TiCp*（硫代水杨酸）M（COD）]（M=Rh（2）；Ir（3））。一氧化碳取代 2 和 3 中的 COD 配体，得到相应的二羰基配合物[TiCp*（硫代水杨酸）M（CO）]（M=Rh（4）；Ir（5））。化合物 4 与 PPh 反应生成单羰基衍生物[TiCp*（硫代水杨酸）Rh（CO）（PPh）]（6）。化合物 1 与 LiBu 反应生成四金属配合物[{TiCp*（硫代水杨酸）Li}（THF）（HO）]（7）。化合物 7 与[RuCpCl（COD）]反应生成杂金属配合物[TiCp（硫代水杨酸）RuCp*]（8）。通过 X 射线衍射研究了化合物 4、5 和 7 的分子结构。通过循环伏安法（CV）和方波伏安法（SWV）实验，我们观察到，钛配合物 1 的钛部分通过硫原子连接到后过渡金属部分对 Ti（iv）金属中心的还原行为有显著影响。因此，单价 1 在-1.15 V 相对于 SCE 呈现不可逆还原过程，而杂金属配合物 2-6 的 CV 则以 Ti（iv）/Ti（iii）系统的可逆或准可逆单电子还原为特征，表明 Ti（iii）还原物种得到了显著稳定。同样，取代物 2 和 3 中的 M（COD）二烯烃片段由 M（CO）含羰基的片段（在化合物 4 和 5 中）取代，导致钛 E 还原氧化还原电位显著正移。
