Reactivity of the Metal→BX₃ Dative σ-Bond: 1,2-Addition Reactions of the Fe→BX₃ Moiety of the Ferraboratrane Complex [κ⁴-B(mim^{Bu^t})₃]Fe(CO)₂

The ferraboratrane [κ4-B(mimBut)3]Fe(CO)2 (mimBut = 2-mercapto-1-tert-butylimidazolyl), the first example of a complex which possesses a retrodative (i.e., metal-to-ligand) Fe→B bond, is obtained via reaction of the tris(2-mercapto-1-tert-butylimidazolyl)hydroborato complex [TmBut]FeCl with LiCH2SiMe3 followed by treatment with CO. Significantly, [κ4-B(mimBut)3]Fe(CO)2 exhibits novel reactivity towards a variety of reagents that results in eradication of the Fe→B bond via a formal 1,2-addition process and the formation of B-functionalized tris(mercaptoimidazolyl)borate derivatives, [XTmBut]FeY.