Reactivity Studies on 2,3,4,5‐Tetraethyl‐1,6‐diiodo‐2,3,4,5‐tetracarba‐nido‐hexaborane(6): Synthesis and Structures of New C₄B₂nido‐Carborane Derivatives

Abstract

Keywords: Boron / Carboranes / Nucleophilic substitution / Iron / CobaltThe reactivity of the title compound 2,3,4,5-tetraethyl-1,6-diiodo-2,3,4,5-tetracarba-nido-hexaborane(6) (1) towards a variety of nucleophiles is reported. When 1 is treated with RC 2 Li (R = Ph, tBu, SiMe 3 , p-tolyl) and Ph 2 PLi, the corresponding new C 4 B 2 nido-carborane derivatives 2a−d and 3, respectively, are obtained by selective substitution at the basal B−I group, whereas the apical B−I bond remains inert. The reaction of 1 with K[(η 5 -C 5 H 5 )Fe(CO) 2 ] affords the novel species 4, which contains a CpFe(CO) 2 fragment σ-bonded to the basal boron atom of the C 4 B 2 cluster. Attempts to isolate 4 by chromatography on silica gel led to cleavage of the Fe−B bond and formation of compound 5, containing a basal BH vertex, which can be separately prepared by the reaction of 1 and LiBEt 3 H. In the reactions of 1 with PhLi and Me 3 SnLi, respectively, 6a and 7a are formed as the predominant B6-substituted carborane products. In addition, trace amounts of

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