MOLECULAR AND CRYSTAL STRUCTURE OF DIMETHYL-1,6-DICARBACLOVONONABORANE(9)

The molecule of B7H7C2(CH3)2, dimethyl-1,6-dicarbaclovononaborane(9), has C2v symmetry. Distortions of the B7C2 unit are only slight from an idealized B9 polyhedron based upon a tricapped prism of D3h symmetry. The C atoms, with attached CH3 groups, are at two of the three apices of the tricapped prism. Cumulative charges in the six highest filled molecular orbitals give in order of increasing charge B8 (attached to no C atom), B4 (B5, B7, B9) (attached to one C), and B2 (B3) (attached to two C atoms). The crystal structure as determined at —40° is of symmetry P21/a with eight molecules in the unit cell of parameters a = 13.59, b = 11.11, c = 12.47 Å, and β = 93.19°. The 1883 observed X-ray reflections were refined to R = ∑||Fo| — |Fc||/∑|Fo| = 0.04. © 1968, American Chemical Society. All rights reserved.