Peri interactions: an X-ray crystallographic study of the structure of 1,8-bis(dimethylaminonaphthalene)

Abstract

The native anomalous phasing method will have greatest application to cases where poor occupancy or multiple substitution occurs, making direct interpretation of isomorphous difference Pattersons difficult. Alternatively, this method may be useful for locating relative origins for the binding sites from several derivatives in unfavorable space groups, such as P1. The major reasons for the success of the method are that full occupancy of the native anomalous scatterer always occurs, the number and types of binding sites are chemically defined, and the X-ray data are inherently more accurate, since no scaling is needed for anomalous pairs and lack of isomorphism never occurs.The authors wish to thank Drs B. Matthews and G. Kartha for helpful discussions. This work has been supported by NSF Grant No. GB27683 and Life Insurance Medical Research Fund No. G-70-28 Crystals of 1,8-bis(dimethylamino)naphthalene, C14HIsN2, are orthorhombic, space group P212~21, with a= 12.855 (1), b= 10.110 (1), c=9"664 (1)~ and Z=4. A complete structure determination, including refinement of the positions of the hydrogen atoms, led to an R index of 0-053 and a goodness-offit of 2.02 for 1477 reflections. The molecule adopts a conformation in which one carbon atom of each of the dimethylamino groups is eclipsed with respect to the naphthalene ring. Hindrance between the dimethylamino groups and/or resonance interactions between the dimethylamino groups and the aromatic ring are sufficiently great to distort the ring in several ways, the most conspicuous being a sizable increase in the non-bonded C(1)-.. C(8) distance (2.56 ~) compared to the C(4)-.-C(5) distance (2"44 A) and a twisting of the naphthalene ring into a considerably nonplanar conformation. IntroductionThe title compound, N,N,N',N'-tetramethyl-l,8-di- usual basic properties ('the proton sponge'; Alder, Bowman, Steele & Winterman, 1968) and for the steric effects which are expected to be encountered and their influence on the conformation that the molecule will find most favorable. Normally, there is strong resonance interaction between a dimethylamino group and an aromatic ring, so that one might expect a planar conformation to be favored (cf., e.g. Wheland, 1955). However, because of the steric difficulties for compounds such as (I), there is no reasonable possibility of bringing even one of the dimethylamino groups into the plane of the ring. Alternative possibilities include (II), where 1612 PERI INTERACTIONS the methyl groups are out of one another's way but the nitrogen lone pairs are brought face to face; (III), where the lone pairs are favorably situated relative to one another but one pair of methyl groups interferes strongly with a nitrogen atom ; and (IV), a compromise achieved at the expense of some interference between one methyl group on each nitrogen atom and the hydrogens at positions 2 and 7. A further question concerns the amount of ~z character in the C(ring)-N bonds, and whether it might be sufficient to force the nitrogen atoms into planar configurations....

A study of lone-pair interactions of tetracyclic diamines by ultraviolet photoelectron spectroscopy

“…Although amine-to-amine hydrogen bonding is weak, it is expected that 1 is intramolecularly hydrogen bonded and the 1-i,o is the most stable configuration. That partially alkylated 1,8-diaminonaphthalene 4 adopts a conformation with aN-H:N hydrogen bond (1), but 1,8-bis(dimethy1amino)naphthalene is forced to adopt a structure with some lone-pair interaction, supports this expectation (6). While hydrogen bonding would provide a stabilization of approximately 10-15 kJ mol-', a further stabilization would result from a decrease of the lone-pair repulsion because the lone pairs would be directed away from each other.…”

Fluorescent probe conformations: the crystal and molecular structure of hexaaquamagnesium bis(8-anilino-1-naphthalenesulfonate) hexahydrate

“…As observed in other peri or 1,8-disubstituted structures (Balasubramaniyan, 1966;Einspahr, Robert, Marsh & Roberts, 1973;Bright, Maxwell & de Boer, 1973;Robert, Sherfinski, Marsh & Roberts, 1974) the average lengths of the bonds involving the C(1) and C(8) atoms are longer than the average length of the bonds involving the C(4) and C (5) (Cody & Hazel, 1976, 1977 and other naphthalene derivatives (Robert, Sherfinski, Marsh & Roberts, 1974). * A torsion angle a-fl-7-c5 is positive if, when viewed down the fl-y bond, thea-fl bond will eclipse the y-g bond when rotated less than 180 ° in a clockwise direction (Klyne & Prelog, 1960).…”

1,8-Dibenzoyl-2,7-dimethylnaphthalene

“…In naphthalene the H(I)...H(8) distance is 2.50 /~ (Cruickshank, 1957). Similar distances have been reported for 1,8-dimethylnaphthalene [C(I 1)... C(12) 2.93 A, Bright, Maxwell & de Boer, 19731, 1,8-dinitronaphthalene [N(1)...N(2) 2.93 A, Akopian, Kitaigorodskii & Struchkov, 1965], and for 1,8-bis-(dimethylamino)naphthalene [N(1)...N(2) 2.79 /~, Einspahr, Robert, Marsh & Roberts, 1973]. Relief of strain in the present system appears to be achieved partly by distortion from planarity of the naphthalene nucleus, with maximum displacements of individual atoms from the mean C,0 plane of 0.03 (1) A.…”