caa a22 4500 605512817 CHVBK 20210128100657.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00894-015-2736-8 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2736-8 Bonding, aromaticity, and planar tetracoordinated carbon in Si2CH2 and Ge2CH2 [Elektronische Daten] [Stefan Vogt-Geisse, Judy Wu, Paul Schleyer, Henry Schaefer III] Natural bond orbital (NBO) analyses and dissected nucleus-independent chemical shifts (NICS π z z ) were computed to evaluate the bonding (bond type, electron occupation, hybridization) and aromatic character of the three lowest-lying Si2CH2 (1-Si, 2-Si, 3-Si) and Ge2CH2 (1-Ge, 2-Ge, 3-Ge) isomers. While their carbon C3H2 analogs favor classical alkene, allene, and alkyne type bonding, these Si and Ge derivatives are more polarizable and can favor "highly electron delocalized”? and "non-classical”? structures. The lowest energy Si 2CH2 and Ge 2CH2 isomers, 1-Si and 1-Ge, exhibit two sets of 3-center 2-electron (3c-2e) bonding; a π-3c-2e bond involving the heavy atoms (C-Si-Si and C-Ge-Ge), and a σ-3c-2e bond (Si-H-Si, Ge-H-Ge). Both 3-Si and 3-Ge exhibit π and σ-3c-2e bonding involving a planar tetracoordinated carbon (ptC) center. Despite their highly electron delocalized nature, all of the Si2CH2 and Ge2CH2 isomers considered display only modest two π electron aromatic character (NICS(0) π z z =--6.2 to -8.9 ppm, computed at the heavy atom ring center) compared to the cyclic-C 3H2 (-13.3 ppm). Graphical Abstract The three lowest Si2CH2 and Ge2CH2 isomers. Springer-Verlag Berlin Heidelberg, 2015 Main group chemistry nationallicence Planar tetracoordinated carbon nationallicence Natural bond orbital nationallicence 3-center 2-electron bond nationallicence Nuclear-independent chemical shift nationallicence Aromaticity nationallicence Electrostatic potential nationallicence Vogt-Geisse Stefan Facultad de Química, Pontifícia Universidad Católica de Chile, Santiago, Chile aut Wu Judy Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut Schleyer Paul Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut Schaefer III Henry Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-8 1610-2940 21:8<1 2015 21 894 https://doi.org/10.1007/s00894-015-2736-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2736-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vogt-Geisse Stefan Facultad de Química, Pontifícia Universidad Católica de Chile, Santiago, Chile aut NATIONALLICENCE 700 1- Wu Judy Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut NATIONALLICENCE 700 1- Schleyer Paul Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut NATIONALLICENCE 700 1- Schaefer III Henry Center for Computational Quantum Chemistry, University of Georgia, 30602, Athens, GA, USA aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-8 1610-2940 21:8<1 2015 21 894