Bairagi Subhash, Giri Soumen, Joshi Gaurav, Jemmis Eluvathingal D, Ghosh Sundargopal
Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India.
Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore, 560012, India.
Angew Chem Int Ed Engl. 2025 Jan 21;64(4):e202417170. doi: 10.1002/anie.202417170. Epub 2024 Nov 25.
Treatment of [CpTiCl] with [LiBH ⋅ THF] followed by thermolysis with [PhE] (E=S or Se) resulted in the formation of classical diborane(6) complexes, [(CpTi)(η-BHLL')] (L=CHE; L'=CHE; 1 a: E=S, 1 b: E=Se), stabilized at titanium template. To the best of our knowledge, they are the first examples of mono-metallic classical diborane(6) complexes. The bonding analysis and theoretical studies suggest that the stabilization of these diborane(6) species is due to the presence of four bridging ligands in ĸ-fashion, where two of them are phenyl thiolates/selenolates that provide more electrons to the electron-deficient titanium center. Reactions of these diborane(6) species with [M(CO) ⋅ THF] (M=Mo, W) led to the cleavage of the electron-precise B(sp)-B(sp) bond that yielded ĸ-hydridoborato complexes [(CpTi)(ĸ-BHR)(μ-EPh){M(CO)}] (2 a-c: R=H, 3 a-c: R=Ph). In an attempt to isolate the Te-analogue of 1 a-b, a similar reaction was performed; however, the complex was too unstable to be isolated. Interestingly, the treatment of this unstable intermediate with [W(CO) ⋅ THF] yielded [(CpTi)(ĸ-BHR)(μ-TePh){W(CO)}] (2 d: R=H, 3 d: R=Ph) that are analogues of 2 a-c and 3 a-c, respectively. Formation of these species provide indirect evidence for the existence of unstable [(Cp*Ti)(η-BHLL')] (L=CHTe; L'=CHTe; 1 c).
用[LiBH·THF]处理[CpTiCl]，随后与[PhE]（E = S或Se）进行热解，生成了经典的乙硼烷(6)配合物[(CpTi)(η-BHLL')]（L = CHE；L' = CHE；1 a：E = S，1 b：E = Se），它们在钛模板上得以稳定。据我们所知，它们是单金属经典乙硼烷(6)配合物的首个实例。键合分析和理论研究表明，这些乙硼烷(6)物种的稳定性归因于四个以κ-方式的桥连配体的存在，其中两个是苯硫醇盐/苯硒醇盐，它们为缺电子的钛中心提供了更多电子。这些乙硼烷(6)物种与[M(CO)·THF]（M = Mo，W）反应导致电子精确的B(sp)-B(sp)键断裂，生成了κ-氢硼基配合物[(CpTi)(κ-BHR)(μ-EPh){M(CO)}]（2 a - c：R = H，3 a - c：R = Ph）。为了分离1 a - b的碲类似物，进行了类似的反应；然而，该配合物过于不稳定，无法分离。有趣的是，用[W(CO)·THF]处理这个不稳定的中间体，得到了[(CpTi)(κ-BHR)(μ-TePh){W(CO)}]（2 d：R = H，3 d：R = Ph），它们分别是2 a - c和3 a - c的类似物。这些物种的形成间接证明了不稳定的[(Cp*Ti)(η-BHLL')]（L = CHTe；L' = CHTe；1 c）的存在。
