Low-temperature single-crystal X-Ray diffraction,¹H and¹³C solid-state NMR and¹⁴N NQR studies of 1,8-bis(dimethyl-amino)naphthalene

Abstract

Low-temperature ' 3C and ' H MAS NMR and 14N NQR spectra of solid 1,8-bis(dimethyIamino)naphthalene (DMAN) have been measured. X-Ray diffraction shows that the molecule is more symmetric than at room temperature. The low-temperature geometry of DMAN is very similar to the a6 inifio optimized geometry. Solid-state NMR and nuclear quadrupole resonance (NQR) confirm the symmetry of the molecule at low temperature despite the asymmetry of intermolecular interactions in the crystal. Experimental values of the principal components of electric field gradients at 14N, which characterize the properties of the lone pair electrons of the nitrogen atoms, are in good agreement with the ab inifio calculated values.

Dative N→P/Si Interactions — A Historical Approach [1]

“…Bulky peri-substituents had been recognized to cause an enlargement of the bay angles, mainly or even solely of the inner angle whereas the exocyclic angles even could be smaller than 120°. This is what has actually been observed [50,56]. In bis(2,2'-biphenylylene)-(DAN)phosphorane, DAN-P(C 12 H 8 ) 2 3) , a splay angle of ϩ3.2°had been determined, and from the distance d(P···N) ϭ 281.0 pm it had been concluded that, while this is shorter than the van der Waals sum of 3.4 Å , it is not indicative of a bonding interaction of any appreciable magnitude [55].…”

“…It had been recognized that interatomic distances shorter than Σr(vdW) occur, and these short distances had been ascribed to steric strain resulting from the geometry of the naphthalene skeleton. Correspondingly, in the proton sponge TM , the methyl groups at N occupy positions in the anti hemicircle with respect to the C(1)···C(8) connecting line and force the electron pairs into the syn hemicircle [50,56]. It had been invariably found for peri-disubstituted naphthalenes without bonding between the substituents that the intersubstituent distance exceeds 250 pm and that the splay angle of the peri-bonds is positive.…”

Cryogenic stabilization of high vapor pressure samples for surface analysis under ultrahigh vacuum conditions

“…This hydrogen is known to bind between the two aniline/amino type nitrogen atoms into structures that have been confirmed by nuclear magnetic resonance ͑NMR͒ and x-ray diffraction ͑XRD͒ studies. 6,8,10,[12][13][14][15][16] For those involved in studies of proton sponges it is well known ͑both from theoretical and experimental studies͒ that there is only one hydrogen in the ͓N-H . .…”

Solid-state NMR and x-ray diffraction studies of ionic complex of 1,8-bis(dimethylamino)naphthalene (DMAN) with picrolonic acid

“…7,[16][17][18][19][20][21] Conventional 1 H-13 C CP/MAS and Table 2. The average chemical shift of the carbon nuclei at the peri positions (1 and 8) is 145·1(5) ppm, whereas in DMANH + xPA Ϫ it is 146·2 ppm.…”