Carboranophanes

Rearrangements in icosahedral boranes and carboranes revisited

“…This leads to the very familiar deltahedron geometries for closo -C x B n − x H n − x +2 with n +1 skeletal electron pairs, nido- C x B n − x H n − x +4 with n +2 skeletal electron pairs, and arachno -C x B n − x H n − x +6 with n +3 skeletal electron pairs, determined empirically by Wade’s Rules [ 1 , 2 , 15 , 16 ]. Although a great deal of time has been spent in comparing and contrasting carborane systems of varying size in terms of stability, rearrangement, and reactivity [ 7 , 8 , 17 – 23 ], a special effort has been expended in understanding closo - \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{B}}_{{12}} {\text{H}}^{{2 - }}_{{12}}$$\end{document} , closo -C 2 B 10 H 12 , and their respective derivatives [ 21 , 24 – 29 ], which is due primarily to their unusually high stability. An eclectic array of mechanisms have been quite naturally suggested for the intermolecular rearrangement of closo -C 2 B 10 H 12 , from those involving highly symmetric cubeoctahedral and anticubeoctahedral transition states to those with relatively simple triangular face rotations (TFRs) and diamond–square–diamond (DSD) steps [ 4 , 5 , 20 , 25 , 30 – 36 ].…”

“…An eclectic array of mechanisms have been quite naturally suggested for the intermolecular rearrangement of closo -C 2 B 10 H 12 , from those involving highly symmetric cubeoctahedral and anticubeoctahedral transition states to those with relatively simple triangular face rotations (TFRs) and diamond–square–diamond (DSD) steps [ 4 , 5 , 20 , 25 , 30 – 36 ]. Rearrangements in substituted icosahedral C 2 B 10 H 12 have been studied experimentally by way of 10 B-labeling, halogen substitution, methyl substitution, and even tethered linkages [ 3 , 24 , 28 , 36 , 37 ] in the hopes that the electronic structure of the cage will be preserved.…”

Rearrangements in icosahedral boranes and carboranes revisited

“…, closo-C 2 B 10 H 12 , and their respective derivatives [21,[24][25][26][27][28][29], which is due primarily to their unusually high stability. An eclectic array of mechanisms have been quite naturally suggested for the intermolecular rearrangement of closo-C 2 B 10 H 12 , from those involving highly symmetric cubeoctahedral and anticubeoctahedral transition states to those with relatively simple triangular face rotations (TFRs) and diamond-squarediamond (DSD) steps [4,5,20,25,[30][31][32][33][34][35][36].…”

Rearrangements in icosahedral boranes and carboranes revisited

“…An eclectic array of mechanisms have been quite naturally suggested for the intermolecular rearrangement of closo-C 2 B 10 H 12 , from those involving highly symmetric cubeoctahedral and anticubeoctahedral transition states to those with relatively simple triangular face rotations (TFRs) and diamond-squarediamond (DSD) steps [4,5,20,25,[30][31][32][33][34][35][36]. Rearrangements in substituted icosahedral C 2 B 10 H 12 have been studied experimentally by way of 10 B-labeling, halogen substitution, methyl substitution, and even tethered linkages [3,24,28,36,37] in the hopes that the electronic structure of the cage will be preserved.…”

“…This leads to the very familiar deltahedron geometries for closo-CxBn−xHn−x+2 with n+1 skeletal electron pairs, nido-CxBn−xHn−x+4 with n+2 skeletal electron pairs, and arachno-C x B n−x H n−x+6 with n+3 skeletal electron pairs, determined empirically by Wade's Rules [1,2,15,16]. Although a great deal of time has been spent in comparing and contrasting carborane systems of varying size in terms of stability, rearrangement, and reactivity [7,8,[17][18][19][20][21][22][23], a special effort has been expended in understanding closo-B 12 H 12 2À , closo-C 2 B 10 H 12 , and their respective derivatives [21,[24][25][26][27][28][29], which is due primarily to their unusually high stability. An eclectic array of mechanisms have been quite naturally suggested for the intermolecular rearrangement of closo-C 2 B 10 H 12 , from those involving highly symmetric cubeoctahedral and anticubeoctahedral transition states to those with relatively simple triangular face rotations (TFRs) and diamond-squarediamond (DSD) steps [4,5,20,25,[30][31][32][33][34][35][36].…”