We report the synthesis of high-valent molybdenum(VI) bis-imido complexes 1–4 with dipyrromethene (DPM) supporting ligands of the general formula (DPM^R)Mo(NR′)₂Cl (R, R′ = mesityl (Mes) or tert-butyl (^tBu)). The electrochemical and chemical properties of 1–4 reveal unexpected ligand noninnocence and reactivity. ¹⁵N NMR spectroscopy is used to assess the electronic properties of the imido ligands in the tert-butyl complexes 1 and 3. Complex 1 is inert toward ligand (halide) exchange with bulky phenolates such as KOMes or amides (e.g., KN(SiMe₃)₂), whereas the use of the lithium alkyl LiCH₂SiMe₃ results in a rare nucleophilic β-alkylation of the DPM ligand. While the reductions of the complexes occur at molybdenum, the oxidation is centered at the DPM ligand. Quantum-chemical calculations (complete active space self-consistent field, density functional theory) suggest facile (near-infrared) interligand charge transfer to the imido ligand, which might preclude the isolation of the oxidized complex [1]⁺ in the experiment.

中文翻译：

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二吡咯亚甲基配体的钼（VI）双亚氨基配合物。

我们报告的高价钼（VI）合成双-酰亚胺配合物1 - 4与二吡咯亚甲基（DPM）支撑所述通式（DPM的配体^{- [R} ）的Mo（NR'）₂氯（R，R'=异亚丙基丙酮（MES ）或叔丁基（^t Bu））。的电化学和化学性质1 - 4揭示了意想不到的配体noninnocence和反应性。¹⁵ N NMR光谱用于评估叔丁基配合物1和3中亚氨基配体的电子性质。综合大楼1对大量的酚盐（例如KOMes或酰胺类，例如KN（SiMe ₃）₂）交换配体（卤化物）是惰性的，而使用LiCH ₂烷基锂SiMe _3则导致DPM配体的罕见亲核β-烷基化。虽然复合物的还原发生在钼，但氧化集中在DPM配体上。量子化学计算（完整的活性空间自洽场，密度泛函理论）表明，容易的（近红外）配体电荷转移到亚氨基配体上，这可能会阻止实验中氧化复合物的分离[1] ⁺。