“…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].…”