BH3like

BH3like is a term used in chemistry to denote boron-centered fragments or species that resemble borane BH3 in geometry and reactivity. In this sense, BH3like refers to three-coordinate boron centers that are electron-deficient and thus behave as Lewis acids. The concept is descriptive rather than a strict chemical designation, and it is often used to discuss a variety of boron-containing reagents, intermediates, or motifs that mimic the key features of BH3.

In practice, BH3like fragments are stabilized or observed when BH3 associates with electron-donating ligands or bases. Classic examples include adducts such as BH3·THF or BH3·SMe2, where a Lewis base ligates to the boron center, reducing its reactivity and enabling isolation or use in stoichiometric and catalytic processes. BH3like behavior also appears in boron hydride chemistry, where BH3 units participate in three-center-two-electron bonds, as in diborane (B2H6) and related clusters, and in various organoboron reagents used for hydroboration reactions.

The term is particularly relevant in discussions of frustrated Lewis pairs (FLPs), where a bulky Lewis base and a BH3like boron Lewis acid coexist but cannot form a stable adduct, enabling activation of small molecules. It also appears in the context of hydroboration chemistry, where boron centers act as electrophiles that add across unsaturated substrates to form organoboron compounds.

Overall, BH3like serves as a shorthand for boron-centered, electron-deficient motifs that resemble BH3 in structure and reactivity, highlighting their role as Lewis acids and their involvement in boron chemistry, including adduct formation, cluster bonding, and hydroboration processes.