Synthetic and Structural Studies of 1,8-Chalcogen Naphthalene Derivatives

• Published in: Chemistry : a European journal 2010-07, Vol.16 (25), p.7503-7516
• Main Authors: Knight, Fergus R., Fuller, Amy L., Bühl, Michael, Slawin, Alexandra M. Z., Woollins, J. Derek
• Format: Article
• Language: English
• Subjects: ab initio calculations; Atomic beam spectroscopy; chalcogens; Chalcogens - chemical synthesis; Chalcogens - chemistry; Chemistry; Crystallography; Crystallography, X-Ray; density functional calculations; Derivatives; Infrared spectroscopy; Magnetic Resonance Spectroscopy; Molecular Conformation; Molecular structure; Naphthalene; Naphthalenes - chemical synthesis; Naphthalenes - chemistry; NMR; NMR spectroscopy; Nuclear magnetic resonance; peri-substitution; Spectroscopy, Near-Infrared; Spectrum analysis; Structure-Activity Relationship; Sulfhydryl Compounds - chemical synthesis; Sulfhydryl Compounds - chemistry; X-ray diffraction; X-rays
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200903523

Four novel 1,8‐disubstituted naphthalene derivatives 4–7 that contain chalcogen atoms occupying the peri positions have been prepared and fully characterised by using X‐ray crystallography, multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular distortion due to noncovalent substituent interactions was studied as a function of the bulk of the interacting chalcogen atoms and the size and nature of the alkyl group attached to them. X‐ray data for 4–7 was compared to the series of known 1,8‐bis(phenylchalcogeno)naphthalenes 1–3, which were themselves prepared from novel synthetic routes. A general increase in the E⋅⋅⋅E′ distance was observed for molecules containing bulkier atoms at the peri positions. The decreased S⋅⋅⋅S distance from phenyl‐1 and ethyl‐4 analogues is ascribed to a weaker chalcogen lone pair–lone pair repulsion acting in the ethyl analogue due to the presence of two equatorial S(naphthyl) ring conformations. Two novel peri‐substituted naphthalene sulfoxides of 1, Nap(OSPh)(SPh) 8 and Nap(OSPh)2 9, which contain different valence states of sulfur, were prepared and fully characterised by using X‐ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular structures were analysed by using naphthalene ring torsions, peri‐atom displacement, splay angle magnitude, S⋅⋅⋅S interactions, aromatic ring orientations and quasi‐linear OS⋅⋅⋅S arrangements. The axial S(naphthyl) rings in 8 and 9 are unfavourable for S⋅⋅⋅S contacts due to stronger chalcogen lone pair–lone pair repulsion. Although quasi‐linear OS⋅⋅⋅S alignments suggest attractive interaction is conceivable, analysis of the B3LYP wavefunctions affords no evidence for direct bonding interactions between the S atoms. Close enough to bond? Are atoms bonded when they are closer than the sum of their Van der Waals radii? peri‐Substituted systems allow us the opportunity to test weak interactions between chalcogens (see figure).