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

The synthesis, structure, and reaction chemistry of iron carbonyl boryl complexes are described. Bis(boryl) complexes were prepared by reaction of Na2[Fe(CO)4] with chlorocatecholborane and substituted chlorocatecholboranes. An X-ray diffraction study of [Fe(CO)4(BCat*)2] (BCat* = −BO2C6H3-4-t-Bu) was performed and showed significant distortions from octahedral geometry. These bis(boryl) complexes underwent exchange reactions with alcohols, amines, and silylamides. They were converted to anionic compounds by reaction with LiN(SiMe3)2, and these anionic boryls are the first such examples. The anionic character allowed for nucleophilic substitutions. These complexes reacted with ClSnMe3 to yield a mixed boryl−stannyl compound in high yield. In contrast, reaction with methyl iodide or methyl triflate did not lead to an isolable alkylboryl complex. Instead, rapid formation of MeBCat occurred, a rare transformation that substitutes a boryl group for halide.