Si−F bond cleavage of fluoro-silanes was achieved by transition-metal complexes under mild and neutral conditions. The Iridium-hydride complex [Ir(H)(CO)(PPh₃)₃] was found to readily break the Si−F bond of the diphosphine- difluorosilane {(o-Ph₂P)C₆H₄}₂Si(F)₂ to afford a silyl complex [{[o-(iPh₂P)C₆H₄]₂(F)Si}Ir(CO)(PPh₃)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative IrSi interaction plays a crucial role. The IrSi interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of H^δ+⋅⋅⋅F^δ− interaction. Then the Si−F and Ir−H bonds are readily broken to afford the silyl complex and HF through σ-bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh₃)₃] was found to promote the cleavage of the Si−F bond of the triphosphine-monofluorosilane {(o-Ph₂P)C₆H₄}₃Si(F) even at ambient temperature.

The oxidative addition of BF₃ to a platinum(0) bis(phosphine) complex [Pt(PMe₃)₂] (1) was investigated by density functional calculations. Both the cis and trans pathways for the oxidative addition of BF₃ to 1 are endergonic (ΔG°=26.8 and 35.7 kcal mol⁻¹, respectively) and require large Gibbs activation energies (ΔG°^≠=56.3 and 38.9 kcal mol⁻¹, respectively). A second borane plays crucial roles in accelerating the activation; the trans oxidative addition of BF₃ to 1 in the presence of a second BF₃ molecule occurs with ΔG°^≠ and ΔG° values of 10.1 and −4.7 kcal mol⁻¹, respectively. ΔG°^≠ becomes very small and ΔG° becomes negative. A charge transfer (CT), FBF₃, occurs from the dissociating fluoride to the second non-coordinated BF₃. This CT interaction stabilizes both the transition state and the product. The BF σ-bond cleavage of BF₂Ar^F (Ar^F=3,5-bis(trifluoromethyl)phenyl) and the BCl σ-bond cleavage of BCl₃ by 1 are accelerated by the participation of the second borane. The calculations predict that trans oxidative addition of SiF₄ to 1 easily occurs in the presence of a second SiF₄ molecule via the formation of a hypervalent Si species.

Synergistic effects between a transition metal and an appropriate ligand are required to promote a desired catalytic reaction. Ancillary ligands, provided by the versatile functionality of certain elements, give rise to an almost infinite potential for catalytic applications. Recently, the study of the synergistic effect between transition metals and boron has become easy on account of the development of various rigid multidentate frameworks. In this Review, we mainly focus on the chemistry of σ-acceptor (Z-type) borane ligands, particularly the key achievements of their unique reactivity and catalytic applications. Conceptually, the unique character of σ-acceptor borane ligands provides a new strategy for developing remarkable reactivity and novel catalytic applications. This study discusses recent developments in the field in this context. The chemistry of boron-based multidentate ligands that involve a covalent MB bond such as the boryl ligand (BR₂), in which a boron moiety serves as a strong electron-donating ligand, is also rapidly developing. The effect of the boryl ligand on a metal center is totally different from that of the borane (BR₃) ligand, and different boron-based functionalities confer opposing electronic properties to the metal center. The interesting character of boryl-based chelating ligands augments their unique coordination chemistry, which is also summarized in this context.