Topological ring-current and bond-current properties of the altans of certain K-factorizable conjugated systems containing "fixed" single-bonds.
The rudimentary Hückel-London-Pople-McWeeny (HLPM) formalism, which frequently mimics the predictions of more-sophisticated ab initio approaches, is used to investigate the π-electron ring-current and bond-current properties of four novel altan-structures, the parents of three of which are conjugated structures with "fixed" single carbon-carbon bonds: namely, acenaphthylene, fluoranthene, and perylene. Such structures are nowadays sometimes called "K-factorizable". Non-K-factorizable peropyrene is also considered, for comparison. The remarkably contrasting sizes of the bond-currents in the unshared bonds situated in the centers of perylene and peropyrene, first noted more than 40 years ago, are preserved in the corresponding bonds of the respective altan-structures. Current patterns in the parent structures frequently remain semiquantitatively intact when the parent is formally converted to the corresponding altan, a finding that largely agrees with the predictions of previous ab initio calculations. The circulations around the [4n]-perimeters of all four of the altans considered here are (as expected) in the clockwise (paramagnetic) direction.
†University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England, United Kingdom.
Timothy K
TK
Dickens
‡School of Physical Sciences, University of Kent, Canterbury CT2 7NH, England, United Kingdom.
Roger B
RB
Mallion