The structure of BCl2: ESR study of an x-irradiated crystal of BCl3

Abstract

X irradiation of a single crystal of boron trichloride at 77 K yields at least two different radicals. A brief exposure to UV irradiation, however, leaves only one radical whose ESR spectrum shows hyperfine coupling from one boron (10B, 11B) and two equivalent chlorine (35Cl, 37Cl) nuclei and which is identified as BCl2. The g tensor, 11B magnetic hyperfine tensor, 35Cl magnetic and quadrupole hyperfine tensors have been determined and analyzed in terms of the radical’s electronic structure. Problems arising in relating the principal direction of the various tensors to the molecular geometry are discussed. BCl2 is nonlinear with a ClBCl angle of approximately 122° and with the unpaired electron mainly localized on the boron atom.

Boryls Bound to Iron Carbonyl. Structure of a Rare Bis(boryl) Complex, Synthesis of the First Anionic Boryl, and Reaction Chemistry That Includes the Synthetic Equivalent of Boryl Anion Transfer

“…We − and others − have been pursuing the fundamental chemistry of transition-metal boryl complexes. This class of compounds is important as intermediates in transition-metal-catalyzed hydroboration with catecholborane and analogs ,− as well as diboration with catecholate-substituted diboron compounds. , They can impart electrophilic character to low-valent metal complexes and may participate in metal−ligand multiple bonding through weak π-interactions that result from the similarity of the frontier orbitals to carbene ligands. − The existence of the free boryl fragment has been controversial, − and examples of two-coordinate boron-centered radicals are limited. , Transition metals, thus, stabilize these reactive main-group fragments as they often stabilize organic reactive intermediates. Few examples of well-characterized boryl complexes exist, and even fewer examples of bis(boryl) compounds are known. , Anionic boryl transition-metal complexes were unknown prior to this work.…”

“…[29][30][31][32] The existence of the free boryl fragment has been controversial, [33][34][35][36] and examples of twocoordinate boron-centered radicals are limited. 37,38 Transition metals, thus, stabilize these reactive main-group fragments as they often stabilize organic reactive intermediates. Few examples of well-characterized boryl complexes exist, and even fewer examples of bis(boryl) compounds are known.…”