Synthesis, Molecular Structure, and Electrochemistry of 1‐Ferrocenyl‐1,2‐dicarba‐<i>closo</i>‐dodecaboranes

Abstract

Abstract Bis(dimethylsulfido)decaborane, 6,9‐(Me 2 S) 2 ‐ arachno ‐B 10 H 12 , reacts smoothly with ferrocenyl alkynes FcC≡CR [ 1a – h ; Fc = ferrocenyl, R = H ( 1a ), CH 3 ( 1b ), Ph ( 1c ), 4‐MeO 2 CC 6 H 4 ( 1d ), Fc ( 1e ), C≡CFc ( 1f ), C(O)CH 3 ( 1g ), and CO 2 CH 2 CH 3 ( 1h )] to afford the corresponding 1‐ferrocenyl‐1,2‐dicarba‐ closo ‐dodecaboranes 2a – h in good yields. Ester 2h was further reduced to the respective hydroxymethyl derivative, 1‐Fc‐2‐CH 2 OH‐1,2‐ closo ‐C 2 B 10 H 10 ( 3 ). The reaction of 6,9‐(Me 2 S) 2 ‐B 10 H 12 with FcC≡CSiMe 3 proceeded in a different manner to produce (among other products) an SMe 2 adduct of an opened decaborane substituted with a 2‐ferrocenyl‐2‐(trimethylsilyl)ethen‐1‐yl group ( 4 ). This compound probably results through hydroboration of the starting alkyne and migration of the SiMe 3 group. All prepared compounds were characterized by spectroscopic methods ( 1 H, 13 C, and 11 B NMR spectroscopy, IR spectroscopy, and mass spectrometry), and their molecular structures were determined by single‐crystal X‐ray diffraction analysis. In addition, the compounds were studied by cyclic and differential pulse voltammetry on a platinum disc electrode to reveal simple ferrocenyl‐centered oxidations for the singly ferrocenylated carboranes and two consecutive oxidation waves for compounds 2e and 2f , which possess two ferrocenyl substituents.