Selective cage boron/carbon extrusion reaction of 13-vertex carborane μ-1,2-(CH2)3–1,2-C2B11H11: formation of nido-CB10, closo-CB10, and closo-C2B10 species

Abstract

The nature of nucleophiles greatly influences the reactivity patterns of 13-vertex carboranes. μ-1,2-(CH(2))(3)-1,2-C(2)B(11)H(11) reacts with Et(3)N/MeOH, pyridine or bipyridine to give cage-boron and -carbon extrusion products nido-CB(10) or closo-CB(10), or a cage-boron extrusion compound closo-C(2)B(10) while the cage-carbon extrusion species closo-CB(11) monoanions are produced by treatment with MeOH or Ph(3)P.

Supercarboranes: Achievements and perspectives

“…On the other hand, reaction of μ-1,2-(CH 2 ) 3 -1,2-C 2 B 11 H 11 with pyridine (Py) at -30 °C gives another 11-vertex closo complex μ-2,4-(CH 2 ) 3 CHBH(Py) 2 -2-CB 10 H 9 in 56 % isolated yield. Interestingly, treatment of μ-1,2-(CH 2 ) 3 -1,2-C 2 B 11 H 11 with 1 equiv of bipyridine (bipy) at 60 °C affords a 12-vertex carborane 4-B(bipy)-μ-1,2-(CH 2 ) 3 -1,2-C 2 B 10 H 9 in 59 % isolated yield (Scheme 9) [26]. These results show that 13-vertex carboranes have a very diverse reactivity pattern, depending upon the nature of nucleophiles.…”

Reaction of N-heterocyclic carbenes with 13-vertex closo-carboranes: synthesis and structural characterization of zwitterionic salts of 13-vertex nido-carboranes

“…5 1,2-(CH 2 ) n -1,2-C 2 B 11 H 11 (n = 3, 4) reacts also with various nucleophiles to give the cage boron and/or carbon extrusion products closo-CB 11 − , nido-CB 10 − , closo-CB 10 − , or closo-C 2 B 10 depending on the nature of the nucleophiles. [15][16][17][18][19] On the other hand, 12-vertex o-carboranes react with Nheterocyclic carbenes (NHCs) to give the imidazolium salts of carborane anions, 20 or 1 : 2 adducts of nido-carboranecarbene, 21 or zwitterionic salts of imidazolium nido-carboranyl 22 depending upon the size of NHCs. The results show that a sterically demanding NHC, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, can stabilize the first intermediate in the deboration reaction of o-carboranes with nucleophiles.…”

Reactions of 13‐Vertex Carboranes with Strong Bases: Synthesis and Structural Characterization of Carborane Monoanions with exo‐π Bonding

“…[13] This 13-vertex carborane can also react with various nucleophiles to give cage-boron-or cage-carbon-extrusion products nido-CB 10 , closo-CB 10 , closo-CB 11 , or closo-C 2 B 10 , depending on the nature of the nucleophile. [14][15][16] When NaH was used as a nucleophile in the reaction with 1,2-(CH 2 ) 3 -1,2-C 2 B 11 H 11 , an unexpected a-deprotonation species, [1,2-CHA C H T U N G T R E N N U N G (CH 2 ) 2 -1,2-C 2 B 11 H 11 ] À , was obtained, which prompted us to study the deprotonation reaction of 13vertex carboranes with strong bases. Herein, we report the synthesis and structural characterization of 13-vertex carborane monoanions with exo C=C p bonding.…”

“…The 13‐vertex carborane 1,2‐(CH 2 ) 3 ‐1,2‐C 2 B 11 H 11 can even undergo single‐electron reduction to give a stable carborane radical anion with [2 n +3] framework electrons 13. This 13‐vertex carborane can also react with various nucleophiles to give cage‐boron‐ or cage‐carbon‐extrusion products nido ‐CB 10 , closo ‐CB 10 , closo ‐CB 11 , or closo ‐C 2 B 10 , depending on the nature of the nucleophile 14–16. When NaH was used as a nucleophile in the reaction with 1,2‐(CH 2 ) 3 ‐1,2‐C 2 B 11 H 11 , an unexpected α‐deprotonation species, [1,2‐CH(CH 2 ) 2 ‐1,2‐C 2 B 11 H 11 ] − , was obtained, which prompted us to study the deprotonation reaction of 13‐vertex carboranes with strong bases.…”