Ab initio MO study of the symmetrical and asymmetrical isomers of bridging alkynylaluminum and alkynylberyllium dimers



The structures of models for known alkynylaluminum- and alkynylberyllium-bridged dimers were predicted using ab initio molecular orbital methods at the HF/6-31G* level. In both cases, the preferred structure has the bridging alkynyl fragments tilted toward one metal center. Structural comparisons and fragment molecular orbital arguments were used to elucidate the electronic factors leading to the distortion. The essential bonding interaction that stabilizes these structures is π complexation of the alkynyl fragment to one of the metal centers. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003