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Polyatomic Molecules without Electron‐Pair Bonds: High‐Spin Trigonal, Tetrahedral, and Octahedral Lithium Clusters
Author(s) -
Glukhovtsev Mikhail N.,
Schleyer Paul Von Ragué
Publication year - 1993
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199300052
Subject(s) - chemistry , unpaired electron , octahedron , valence electron , spin states , crystallography , molecule , valence (chemistry) , electron , polyatomic ion , tetrahedron , core electron , atomic physics , crystal structure , inorganic chemistry , physics , organic chemistry , quantum mechanics
Bound polyatomic molecules without any spin‐paired valence electrons are exemplified by lithium clusters in high‐spin states. Three unpaired valence electrons are able to bind the ( 4 A 1 ) quartet states of Li 3 and of Li 4 + in trigonal (D 3h ) geometries. The tetrahedral Li 4 and Li 5 + ( 5 A 1 ) quintet state structures illustrate bound molecules with four unpaired valence electrons. Five, six, and seven spin‐uncoupled valence electrons bind the square pyramidal Li 5 ( 6 B 1 ) structure, the Li 6 ( 7 A 2u ) distorted octahedral structure, and the Li 6 − ( 8 A 1g ) octahedral (O h ) octuplet, respectively. However, these high‐multiplicity structures are only local minima; forms with lower spin states are more favorable energetically. Other high symmetry, high multiplicity clusters, e.g., triangular Be 3 + ( 6 A 1 ′), also have positive atomization energies. The results demonstrate that chemical bonding in multiatom species does not require spin‐coupling.