Boron Clusters with a Ferrocenylalkynyl Group Bonded to Boron: Synthesis, Characterization, and Electrochemical Trends

Abstract

The 12-vertex closo-boron clusters [1-FcCϵC-closo-B 12 H 11 ] 2-(1), [12-FcCϵC-closo-1-CB 11 H 11 ] -(2), [1-H 2 N-12-FcCϵCcloso-1-CB 11 H 10 ] -(3), and [9-FcCϵC-closo-1,2-C 2 B 10 H 11 ] (5) were synthesized from the corresponding iodinated derivatives and Me 3 SiCϵCMgBr by a Pd-catalyzed Kumada-type cross-coupling reaction. Anion 3 was converted into the inner salt [1-Me 3 N-12-FcCϵCcloso-1-CB 11 H 10 ] (4). The nido-derivative [5-FcCϵC-nido-7,8-C 2 B 9 H 11 ] -(6) was obtained from 5 via a deboronation reaction. The * Prof. Dr. M. Finze ARTICLE Scheme 1. {closo-B 12 } (1), {closo-1-CB 11 } (2-4), {closo-1,2-C 2 B 10 } (5), and {nido-7,8-C 2 B 9 } clusters (6) with one ferrocenylalkynyl group bonded to boron.

Convenient Synthesis of [closo-B10H9-1-I]2– and [closo-B10H8-1,10-I2]2– Anions

“…To a solution of monoiodonium derivative 3[Bu 4 N] (1.00 g, 1.77 mmol) in dry THF (18 mL), 2.5 M n-BuLi in hexanes (3.5 mL, 8.8 mmol) was added dropwise over the period of 5−10 min at −10 °C under argon. The reaction mixture was stirred at −5 °C for 1 h, and a small sample was analyzed by 11 B NMR (more n-BuLi can be added if necessary to complete the reaction). Water (10 mL) was added, THF was removed under reduced pressure, and the clear solution was extracted with hexane (×3).…”

“…One of the most effective ways to form a B–C bond in closo -boranes involves a Pd-catalyzed cross-coupling reaction between an appropriate iodo- closo -borate and an organometallic reagent. This method has extensively been used for substitution of 12-vertex carboranes, derivatives of carbaborate anions, [ closo -1-CB 11 H 12 ] − ( A , Figure ) − and [ closo -1-CB 9 H 10 ] − ( B ), − and dodecaborate anion [ closo -B 12 H 12 ] 2– ( C ) − with alkyl, ,,,− ,, aryl, ,,,,, and alkynyl ,,,,, groups. In contrast, there are no reports of similar coupling reactions for the [ closo -B 10 H 10 ] 2– anion ( D ), the most synthetically available closo -borane, mainly due to the cumbersome access to its iodo derivatives.…”

Thermal and Photophysical Properties of Highly Quadrupolar Liquid‐Crystalline Derivatives of the [closo‐B12H12]2− Anion

“…The B anion is a larger analogue of anion A and has the highest calculated resonance energy among closo clusters . A literature search revealed that there were only a handful of derivatives of anion B with π substituents (phenyl, naphthyl, ethynyl, and ferrocenylethynyl), typically introduced through Pd‐catalyzed C−B cross‐coupling of the appropriate iodoborane with an organometallic reagent, and π‐zwitterionic derivatives that included tropylium and pyridinium . Consequently, there are even fewer photophysical studies of such derivatives, and these concentrate mainly on the zwitterions .…”

Catalyst‐Free Polyhydroboration of Dodecaborate Yields Highly Photoluminescent Ionic Polyarylated Clusters

“…Such systems typically comprise mono or disubstituted carborane derivatives, with rare examples of trisubstitution. Carbon‐substituted carboranes are generally prepared using either substituted alkynes or through metal mediated cross coupling reactions . A review was published recently detailing much of the work in this area .…”