Activation of BH bonds in Ir(I) complexes supported by phosphine with carba-closo-dodecaborate and o-carborane ligand substituents: A DFT investigation

• We successfully explained the BH activation in Ir(I) complexes.
• Two kinds of methods to obtain B-σ-iridium complexes were given.
• Dispersion correction is important for calculating the energy of iridium complexes.

The structures, stability and activation of BH bonds of the twelve kinds of Ir(I) complexes supported by phosphine with o-carborane and carba-closo-dodecaborate ligand substituents, η2-C8H12Ir(I)Cl(PR2(CB11H11−)) and η2-C8H12Ir(I)Cl(PR2(C2B10H11)) (R = Me, iPr and CH(CF3)2) and η2-C8H12Ir(I)Cl(P(CH3)2X(CB11H11−)) and η2-C8H12Ir(I)Cl(P(CH3)2X(C2B10H11)) (X = CH2, NH and O) have been investigated using density functional theory (DFT) BP86 functional. Calculated results indicated that the BH bonds in η2-C8H12Ir(I)Cl(P(CH(CF3)2)2(CB11H11−)) and η2-C8H12Ir(I)Cl(PR2(C2B10H11)) (R = iPr and CH(CF3)2), as well as η2-C8H12Ir(I)Cl(P(CH3)2R(CB11H11−)) and η2-C8H12Ir(I)Cl(P(CH3)2R(C2B10H11)) (R = CH2, NH and O) are both thermodynamically and dynamically favorable to be activated, in which the oxidation addition of BH bond in η2-C8H12Ir(I)Cl(P(iPr)2(C2B10H11)) is consistent with the experimental results. In contrast, the BH bonds in η2-C8H12Ir(I)Cl(P(R)2(CB11H11−)) (R = Me and iPr) and η2-C8H12Ir(I)Cl(P(CH3)2(C2B10H11)) cannot be activated, in which η2-C8H12Ir(I)Cl(P(iPr)2(CB11H11−)) is consistent with the experimental result. The activation of BH bonds in carba-closo-dodecaborate phosphine and o-carborane phosphine of Ir(I) complexes depend up the distance between BH bond and Ir(I). Moreover, two kinds of approaches to obtain B-σ-irridium (III) complexes were given by the activation of BH bonds in Ir(I) complexes.

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