Peri-Substitution: Making Main Group Molecules That Should Not Exist

Unique geometric constraints are imposed on atoms attached to peri-positions (1,8-positions) in naphthalene. Because of the limited space available, the rigid geometry of naphthalene imposes strain on peri-atoms, promoting formation (and retention) of unusually strong bonding interaction between them.
We have used the unique peri-geometry to stabilise normally fleeting species, ranging from low coordinate to hypervalent. In particular, using enforced proximity Lewis base coordination resulted in fundamentally new, broadly applicable method of thermodynamic stabilisation to challenge the paradigms associated with a number of reactive molecules and motifs. The (unstabilised) species in which we are interested dissociate, disproportionate, oligomerise, or otherwise decompose well below room temperature, which severely limits their study and applicability. Our aim is to stabilise a range of normally unstable species to the point that they become bottleable. This facilitates the exploration of normally ephemeral species and thus enables the development of new reactivities and fundamentally new chemistries.
We have also been using the unique energetics landscape of peri-substituted species to promote unusual reactivity, including carbon-element coupling reactions, with view of using these in main-group (i.e. transition metal-free) catalysis.
In addition, forced orbital interactions which lead to highly unusual spectral characteristics will be discussed. These include observable double through space couplings (formally 10J(CP) couplings).

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3. B. A. Chalmers, M. Bühl, K. S. Athukorala Arachchige, A. M. Z. Slawin, P. Kilian
A Structural, Spectroscopic and Computational Examination of the Dative Interaction in Constrained Phosphine–Stibines and Phosphine–Stiboranes, Chem. Eur. J. 2015, 21, 7520–7531, DOI: 10.1002/chem.201500281

4. Major review: P. Kilian, F. R. Knight, J. D. Woollins
Naphthalene and Related Systems Peri-substituted by Group 15 and 16 Elements, Chem. Eur. J. 2011, 17, 2302-2328, DOI: 10.1002/chem.201001750