THE TOPOLOGICAL UNIQUENESS OF THE DELTAHEDRA FOUND IN THE BORANES BNHN2-(6-LESS-THAN-OR-EQUAL-TO-N-LESS-THAN-OR-EQUAL-TO-12)

The deltahedra observed experimentally in the borane anions B(n)H(n)2- (6 less-than-or-equal-to n less-than-or-equal-to 10) are the only possible n-vertex deltahedra having only degree 4 and 5 vertices. The existence of an 11-vertex deltahedron having only degree 4 or 5 vertices is topologically impossible in accord with the presence of a degree 6 vertex in the observed structure for B11H11(2-).