biostudies-literatureUnknown60(24)Trageser TFonds der Chemischen IndustrieThe intriguing (μ-hydrido)diboranes(4) with their prominent pristine representative [B₂ H₅ ]^- have mainly been studied theoretically. We now describe the behavior of the planarized tetraaryl (μ-hydrido)diborane(4) anion [1H]^- in cycloaddition reactions with the homologous series of heterocumulenes CO₂ , iPrNCO, and iPrNCNiPr. We show that a C=O bond of CO₂ selectively activates the B-B bond of [1H]^- , while the μ-H ligand is left untouched ([2H]^- ). The carbodiimide iPrNCNiPr, in contrast, neglects the B-B bond and rather adds the B-bonded H^- ion to its central C atom to generate a formamidinate bridge across the B₂ pair ([3]^- ). As a hybrid, the isocyanate iPrNCO combines the reactivity patterns of both its congeners and gives two products: one of them ([4H]^- ) is related to [2H]^- , the other ([5]^- ) is an analog of [3]^- . We finally propose a mechanistic scenario that rationalizes the individual reaction outcomes and combines them to a coherent picture of B-B vs. B-H bond activation.Angewandte Chemie (International ed. in English)13500-13506https://www.ebi.ac.uk/biostudies/studies/S-EPMC8252796biostudies-literatureB-B vs. B-H Bond Activation in a (μ-Hydrido)diborane(4) Anion upon Cycloaddition with CO₂ , Isocyanates, or Carbodiimides.PMC8252796Bolte MBebej DTrageser TWagner MLerner HWfalseB-B vs. B-H Bond Activation in a (μ-Hydrido)diborane(4) Anion upon Cycloaddition with CO₂ , Isocyanates, or Carbodiimides.The intriguing (μ-hydrido)diboranes(4) with their prominent pristine representative [B₂ H₅ ]^- have mainly been studied theoretically. We now describe the behavior of the planarized tetraaryl (μ-hydrido)diborane(4) anion [1H]^- in cycloaddition reactions with the homologous series of heterocumulenes CO₂ , iPrNCO, and iPrNCNiPr. We show that a C=O bond of CO₂ selectively activates the B-B bond of [1H]^- , while the μ-H ligand is left untouched ([2H]^- ). The carbodiimide iPrNCNiPr, in contrast, neglects the B-B bond and rather adds the B-bonded H^- ion to its central C atom to generate a formamidinate bridge across the B₂ pair ([3]^- ). As a hybrid, the isocyanate iPrNCO combines the reactivity patterns of both its congeners and gives two products: one of them ([4H]^- ) is related to [2H]^- , the other ([5]^- ) is an analog of [3]^- . We finally propose a mechanistic scenario that rationalizes the individual reaction outcomes and combines them to a coherent picture of B-B vs. B-H bond activation.2021-01-01T00:00:00Z2021 Jun2024-11-20T19:09:22.925Z2022-02-10T19:47:14.094ZS-EPMC82527963374031810.1002/anie.202103427