Atomic interactions in a boron-rich carbon-containing icosahedron

Boron carbides contain carbon atoms as substituents for boron in icosahedra. The B-C interaction is different in icosahedra from that in other geometric forms. Para-carborane, p-C/sub 2/B/sub 10/H/sub 12/, offers an excellent system for the study of structure and interactions in boron-rich, carbon-containing icosahedra; its structure is well-characterized experimentally, and the infrared and Raman spectra have been observed and are relatively simple. Here they present an analysis of p-carborane by classical force field methods supplemented by quantum mechanical calculations. Complexity in the model cluster is introduced step-by-step beginning with B/sub 12/ (I/sub h/ symmetry). The principle interaction constants extracted through interpretation of p-C/sub 2/B/sub 10/H/sub 12/ spectra are k/sub CB/ = 2.0 x 10/sup 5/ dyne/cm k/sub BB/ (intrapentagon) = 1.3 x 10/sup 5/ dyne/cm, and k/sub BB/ (interpentagon) - 1.55 x 10/sup 5/ dyne/cm