peri-Interactions in Naphthalenes, 5 [1]. On the Impact of peri-Stress and Trityl-Stress upon the Length of N⁺-C Bonds in 1-Azonia-acenaphthene Cations

Abstract

pen'-Naphthalenes, Steric EffectsIn the 1-azonia-acenaphthene salts 6b and 9, the N+-Cpe"-bond is modestly elongated. While no clear-cut influence of the peri-stress is obvious, incorporation of Cperi in a triarylmethyl structure has a bond-lengthening effect. However, the stretching forces are insufficient to restore the ideal geometry of the naphthalene skeleton.

Naphthyl‐Substituted Carbocations: From peri Interaction to Cyclization

“…[6] We described the preparation and X-ray crystal analysis of the nitrogen-centred model cationic compound 5b in an earlier publication. [2] In this work we monitored closely the formation of 5b by NMR spectroscopy starting from the triarylmethyl alcohol 9 (Scheme 4). The N-methyl groups [9] and the olefinic hydrogen atoms of the suberenyl moiety exhibit diagnostic signals throughout the transformation, allowing identification of the reactive intermediates.…”

“…Triarylmethyl compounds have found widespread application as functional dyes, as exemplified by the prominent indicators phenolphthalein (1) and thymol blue (2). In structurally related naphthalene derivatives, such as the moderately thermochromic naphthofurans 3, [1] the ring strain elongates the peri bond, classified by Schiemenz and co-workers as the peri stress (Scheme 1).…”

“…In structurally related naphthalene derivatives, such as the moderately thermochromic naphthofurans 3, [1] the ring strain elongates the peri bond, classified by Schiemenz and co-workers as the peri stress (Scheme 1). [2] Scheme 1. Examples of classical indicator molecules and thermochromic compounds with a triarylmethyl moiety.…”

peri-Interactions in Naphthalenes, 14 [1]. Pyramidalization versus Planarization at Nitrogen in 8-Dialkylamino-naphth-1-yl Compounds as a Measure of peri Bond Formation

“…In 2-ethyl-1,1,2-trimethyl-1-azonia-acenaphthene [22] (Table 1, In either case, only subset A is relevant for comparison with DAN-X compounds containing a noncoordinating N atom; in both cases, the sum of the angles is slightly smaller than 328.4 • .…”

“…Their high bond energy and stout resistance against bond stretching enables covalent bonds between the peri-bound atoms X and Y in 1-X-8-Y-substituted naphthalenes to cope with the FSR and the GPF and to enforce interatomic distances d(X···Y)< PD [2,3,5,22]. However, such distances are not necessarily restricted to classical covalent bonds.…”