Theoretical studies of multiple bonds in gallium–gallium and germanium–germanium compounds †
2000; Issue: 3 Linguagem: Inglês
10.1039/a907421j
ISSN1470-479X
AutoresThomas L. Allen, William H. Fink, Philip P. Power,
Tópico(s)Advanced Chemical Physics Studies
ResumoA recent publication concerning the synthesis and structure of the compound Na2{GaC6H3-2,6-Trip2}2 (Trip = C6H2-2,4,6-iPr3), which has a trans-bent geometry, has generated considerable discussion owing to the description of its gallium–gallium bond as a triple one. To provide a theoretical perspective on this subject, we have studied a series of model compounds by the methods of molecular electronic structure theory. For the species trans-Li2MeGaGaMe we find a Ga–Ga bond order somewhat less than two, instead of a triple bond, owing to the antibonding character of one of the molecular orbitals. In the isoelectronic trans-MeGeGeMe we find an essentially GeGe double bonded structure. The neutral trans-MeGaGaMe molecule has a weak Ga–Ga single bond rather than a Ga–Ga double bond. Each of these molecules features a lone pair orbital of bu symmetry, with the main regions of electron density located on the gallium or germanium centers, formed by mixing a bonding π orbital and an antibonding σ* orbital in a second-order Jahn–Teller effect.
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