Vibrational frequencies and structural determination of 1,6-dicarba-closo-hexaborane(6)

The normal mode frequencies and corresponding vibrational assignments of 1,6-dicarba-closo-hexaborane(6) are examined theoretically using the GAUSSIAN98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion predicted by a group theoretical analysis (B-B stretch, B-C stretch, B-H stretch, C-H stretch, B-H bend, and C-H bend) utilizing the D(4h) symmetry of the molecule. The vibrational modes of the naturally isotopically substituted (1-(10)B, 2-(10)B 3-(10)B, and 4-(10)B) forms of 1,6-dicarba-closo-hexaborane(6) were also calculated and compared against experimental data. A complex pattern of frequency shifts and splittings is revealed.