Highly Chlorinated, Brominated, and Iodinated Icosahedral Carborane Anions: 1-H-CB(11)X(11)(-), 1-CH(3)-CB(11)X(11)(-) (X = Cl, Br, I); 1-Br-CB(11)Br(11)(-).
Direct chlorination of 1-CH(3)-CB(11)H(11)(-) in glacial acetic acid gave the highly chlorinated carborane anion 1-CH(3)-CB(11)Cl(11)(-), and treatment of 1-CH(3)-CB(11)H(11)(-) with ICl in triflic acid afforded the highly iodinated carborane anion 1-CH(3)-CB(11)I(11)(-). Under similar or more vigorous reaction conditions, however, the reaction of 1-CH(3)-CB(11)H(11)(-) with Br(2) in triflic acid did not proceed to completion. The highly brominated carborane anion 1-CH(3)-CB(11)Br(11)(-) was achieved via a sealed-tube reaction. This new method has led to the isolation of 1-H-CB(11)X(11)(-) (X = Cl, Br, I) and 1-Br-CB(11)Br(11)(-) in high yield. The lithiation of 1-H-CB(11)X(11)(-) resembles that of its parent anion CB(11)H(12)(-). Treatment of these lithio species with methyl iodide gave the methylated carborane anions 1-CH(3)-CB(11)X(11)(-). These new weakly coordinating anions were fully characterized by (1)H, (13)C, and (11)B NMR, IR, and negative-ion MALDI MS spectroscopy. Some were further confirmed by single-crystal X-ray analysis.
Xie
Zuowei
Z
Department of Chemistry, The Chinese University of Hong Kong, Shatin NT, Hong Kong, China.
Tsang
Chi-Wing
CW
Sze
Eric Tung-Po
ET
Yang
Qingchuan
Q
Chan
Dominic T. W.
DT
Mak
Thomas C. W.
TC