The electronic structures of bis(carbonyl)diborane(4), triborane(7) carbonyl and their parent boranes diborane(4) and triborane(7)
✍ Scribed by D.R. Armstrong
- Publisher
- Elsevier Science
- Year
- 1976
- Tongue
- English
- Weight
- 603 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0020-1693
No coin nor oath required. For personal study only.
✦ Synopsis
The electronic structure of bLs(carbonyl)diborane(4), B,H,(CO),, triborane(7) carbonyl, B3H,C0, and their parent boranes have been examined by a non-empirical molecular orbital technique. It is found that the carbonyl groups are weakly bound to the borane portion. The staggered form of B2H4(C0)2 is calculated to be more stable than the eclipsed configuration by 74 W mot'. The structure of B2H, is computed to be two BH2 groups in a staggered conformation joined by a boronboron bond. The following optimised bond lengths, B-B = 1.683 A, B-H = 1.202 A nm, and bond angle LHBH = 116.2" are obtained. The energy of rotation about the boron-boron bond in BzH4 is 57.2 kJ mol-' and optimisation of the geometry of the eclipsed configuration reduces this energy barrier by 6.3 kJ mot'. The electronic situation within the B3 rings of B,H,CO and B3H7 is discussed. The presence of the carbonyl group only marginally alters the bonding within the BBB triangle which consists of a distorted three-centre bond. The bridging hydrogen atom which almost lies in the same plane as the three boron atoms interacts with the inplane orbitals of two of the boron atoms and hence deforms the electronic situation within the ring.