Ghaffari Behnaz, Vanchura Britt A, Chotana Ghayoor A, Staples Richard J, Holmes Daniel, Maleczka Robert E, Smith Milton R
Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824-1322 United States.
Organometallics. 2015 Oct 12;34(19):4732-4740. doi: 10.1021/acs.organomet.5b00525. Epub 2015 Aug 11.
Catalytic C-H borylation using the five-coordinate tris-boryl complex (dippe)Ir(Bpin) (, dippe = 1,2-bis(diisopropylphosphino)ethane) has been examined using P{H} and H NMR spectroscopy. Compound was shown to react rapidly and reversibly with HBpin to generate a six-coordinate borylene complex, (dippe)Ir(H)-(Bpin)(BOCMeCMeOBpin) (), whose structure was confirmed by X-ray crystallography. Under catalytic conditions, the H generated from C-H borylation converted compound to a series of intermediates. The first is tentatively assigned from P{H} and H NMR spectra as (dippe)Ir(HBpin) (), which is the product of formal H addition to compound . As catalysis progressed, compound was converted to a new species with the formula (dippe)Ir(HBpin) (), which arose from H addition to compound with loss of HBpin. Compound was characterized by P{H} and H NMR spectroscopy, and its structure was confirmed by X-ray crystallography, where two molecules with different ligand orientations were found in the unit cell. DFT calculations support the formulation of compound as an Ir agostic borane complex, (dippe)IrH(Bpin)(η-HBpin). Compound was gradually converted to (dippe)Ir(HBpin) (), which was characterized by P{H} and H NMR spectroscopy and X-ray crystallography. DFT calculations favor its formulation as an agostic borane complex of Ir with the formula (dippe)IrH(η-HBpin). Compound reacted further with H to afford the dimeric structure [(dippe)IrH(μ-H)] (), which was characterized by H NMR and X-ray crystallography. Compounds are in equilibrium when H and HBpin are present.
已使用磷氢（P{H}）和氢（H）核磁共振光谱法研究了使用五配位三硼基配合物（二异丙基膦基乙烷）铱（dippe）Ir（Bpin）进行的催化碳氢键硼化反应。结果表明，化合物与HBpin迅速且可逆地反应，生成六配位硼烯配合物（二异丙基膦基乙烷）Ir（H）-（Bpin）（BOCMeCMeOBpin）（），其结构通过X射线晶体学得以确认。在催化条件下，碳氢键硼化反应生成的氢将化合物转化为一系列中间体。首先，根据磷氢和氢核磁共振光谱初步确定为（二异丙基膦基乙烷）Ir（HBpin）（），它是氢正式加成到化合物上的产物。随着催化反应的进行，化合物转化为一种新的物种，其化学式为（二异丙基膦基乙烷）Ir（HBpin）（），它是由氢加成到化合物上并失去HBpin而产生的。通过磷氢和氢核磁共振光谱对化合物进行了表征，并通过X射线晶体学确认了其结构，在晶胞中发现了两个具有不同配体取向的分子。密度泛函理论计算支持将化合物表述为铱的一种σ-配位硼烷配合物（二异丙基膦基乙烷）IrH（Bpin）（η-HBpin）。化合物逐渐转化为（二异丙基膦基乙烷）Ir（HBpin）（），通过磷氢和氢核磁共振光谱以及X射线晶体学对其进行了表征。密度泛函理论计算倾向于将其表述为铱的一种化学式为（二异丙基膦基乙烷）IrH（η-HBpin）的σ-配位硼烷配合物。化合物进一步与氢反应，得到二聚体结构[（二异丙基膦基乙烷）IrH（μ-H）]（），通过氢核磁共振光谱和X射线晶体学对其进行了表征。当存在氢和HBpin时，化合物处于平衡状态。
