Reactivity of the metal→BX3 dative σ-bond:: 1,2-addition reactions of the Fe→BX3 moiety of the ferraboratrane complex [K4-B(mimBut)3]Fe(CO)2 2

The ferraboratrane [kappa(4)-B(mim(But))(3)]Fe(CO)(2) (mim(But))(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, [kappa(4)-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.