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Communication through molecular bridges: Different bridge orbital trends result in common property trends
Author(s) -
Proppe Jonny,
Herrmann Carmen
Publication year - 2015
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23781
Subject(s) - molecular orbital , atomic orbital , bridge (graph theory) , conductance , molecular wire , chemistry , coupling (piping) , chemical physics , computational chemistry , materials science , electron , physics , molecule , condensed matter physics , quantum mechanics , medicine , metallurgy
Common trends in communication through molecular bridges are ubiquitous in chemistry, such as the frequently observed exponential decay of conductance/electron transport and of exchange spin coupling with increasing bridge length, or the increased communication through a bridge upon closing a diarylethene photoswitch. For antiferromagnetically coupled diradicals in which two equivalent spin centers are connected by a closed‐shell bridge, the molecular orbitals (MOs) whose energy splitting dominates the coupling strength are similar in shape to the MOs of the dithiolated bridges, which in turn can be used to rationalize conductance. Therefore, it appears reasonable to expect the observed common property trends to result from common orbital trends. We illustrate based on a set of model compounds that this assumption is not true, and that common property trends result from either different pairs of orbitals being involved, or from orbital energies not being the dominant contribution to property trends. For substituent effects, an effective modification of the π system can make a comparison difficult. © 2014 Wiley Periodicals, Inc.