Abstract
Quantum chemical calculations using DFT (BP86) and ab initio methods (MP2, MP4 and CCSD(T)) have been carried out for the title compounds. The nature of the Pb-Pb interactions has been investigated with an energy decomposition analysis. The energy minimum structures of the halogen substituted Pb2X2 molecules possess a doubly bridged butterfly geometry A like the parent system Pb2H2. The unusual geometry can be explained with the interactions between PbX fragments in the X2Π ground state which leads to one Pb-Pb electron-sharing σ bond and two donor-acceptor bonds between the Pb-X bonds as donor and vacant p(π) AOs of Pb. The energy difference between the equilibrium form A and the linear structure XPb≡PbX (E) which is a second-order saddle point is much higher when X is a halogen atom than for X = H. This is because the a4Σ- ← X2Π excitation energies of PbX (X = F-I) are higher than for PbH. The structural isomers B, D1, D2, E, F1, F2 and G of Pb2X2 are no minima on the potential energy surface.
Original language | English |
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Pages (from-to) | 269-277 |
Number of pages | 9 |
Journal | Theoretical Chemistry Accounts |
Volume | 130 |
Issue number | 2-3 |
DOIs | |
State | Published - Oct 2011 |
Externally published | Yes |
Keywords
- Ab initio calculations
- Bonding analysis
- DFT calculations
- Diplumbaacetylene