The crystal structure of the ti!le compound has been determined by X-ray analysis. The intramolecular hydrogen bond lengths are 2.606(?) A for the (NHN)' bridge in protonated 1,8-bis(dimethyIamino)naphthalene cation (DMAN'H) and 2.401(4) A for the (OH0)-bridge in the hydrogen maleate anion (HM-). The H-bonds are asymmetrical and not strictly linear: NHN, 157(3)" and OHO, 170(5)". The geometries of the N-H. . .N and O-Ha . -0 bridges of the investigated cation and anion are dominated by the spherical repulsions of their constituent atoms.The overlapping bands in the absorbance IR spectra of potassium hydrogen (deuteron) maleate are separated in the second-derivative spectra. The strong mixing of the in-plane modes with skeletal modes in the hydrogen maleate ion causes a larger separation (Av w 115 cm-') of the v(C=O) bands in comparison with those in other type A acid salts containing intermolecular hydrogen bonds (Av z 20-35 cm-'). The observed lack of solvent effect on the IR absorption suggests that the hydrogen bonds in tetrabutylammonium hydrogen maleate and 1,8bis(dimethy1amino)naphthalene hydrogen maleate are not extremely polarizable. 'H and ' 3C NMR chemical shifts of the investigated compound were measured and identified in two-dimensional ( 20) experiments. The ' H NMR spectra show two narrow signals at ca. 19.5 and 18.7 ppm due to the OH0 and NHN protons, respectively. The structural parameters of the cation and anion were also determined by quantum-mechanical calculations with the semiempirical MNDO-PM3 method.
The crystal structure of the title complex h a s been determined by X-ray analysis. All H atoms were located and refined isotropically ; R = 0.041 for 1595 observed reflections. The intramolecula: hydrogen bonds are asymmetrical and are characterized by the following distances and angles: 2.670 (3) . A and 146 (3)" for t h e (NHN)+ bridge in t h e protonated 1,8-diaminonaphthalene cation (DAN+H) and 2.423 (2) A and 177 (3)" for the (OH0)bridge in t h e hydrogen maleate anion (HM-). The NaH, group is engaged in two intermolecular bonds with the anion [N+(H)..-O distances 2.794 (2) and 2.856 (3) 6\]. The interactions of t h e NH, group with the anion are weaker [N(H). --0 distances 3.078 (3) and 3.225 (3) A]. Most of the bond distances and angles in DAN'H -HMare very similar to those in the complex of 1,8-bis(dimethylamino)naphthalene with maleic acid, DMAN+H 1) HM-. The deformations of the naphthalene skeleton in DAN+H.HM-and DMAN+H.HM-are also comparable. In DMAN+H, the proton is located in a cavity formed by four methyl groups, therefore, its exchange is slow on the NMR timescale. In DAN+H t h e proton is not inside a cavity and the exchange becomes rapid. Although spherical repulsions are not negligible, t h e cavity is of prime importance for t h e large basicity of DMAN. The PM3 method reproduces correctly the cation structure and its interactions with t h e anion but t h e 0. + .O distance in the anion is too long. The AM1 method failed to reproduce t h e structure of the complex correctly.'Proton sponges' are commonly associated with 1,8-bis(dimethylamino)naphthalene, DMAN, and its derivatives. The extraordinarily high basicity'-, of these compounds has led to a continuous interest in their proper tie^.'.^-'^.Recently we have studied the H-bonds in the complex of 1 ,8-bis(dimethylamino)naph thalene with maleic acid, DMAN'H-HM-, and found that the geometries of the N-H...N and O-H*.-O bridges of the cation and anion are dominated by spherical repulsions of their constituent atoms.', In this paper we extend our investigations to include a complex of the parent compound, 1,sdiaminonaphthalene-maleic acid, DAN" H HM -, to answer the question why only tetraalkyl derivatives of 1,8diaminonaphthalene are more basic than most aliphatic a m i n e ~. ~ DAN is not a proton sponge (pK, = 4.61; cf. pK, = 12.1 for DMAN);' its structure has been determined by X-ray crystallography. I 2 * I 4 Experimental DAN was purified by crystallization from methanol-water. DAN'H'HM-was prepared by mixing maleic acid (0.01 mol) with DAN (0.01 mol) in 2 cm3 acetonitrile. The product was recrystallized from ethanol; mp 140-141 "C.
2+ 2-C4HI4N2 . H2P207, Mr = 266"1, monoclinic, C2/c, a = 16-569 (2), b --8.4497 (6), c = 7.998 (1)A, # =96"282 (9) °, V= 1113.0 (2)A), Z= 4, Dm= 1.570, Dx = 1.587 g cm -3, A(Mo Ka) = 0.71069/~, /z --3.49 cm-1, F(000) = 560, T = 290 K, R = 0.030 for 862 observed reflections. The putrescinium dication is located on a center of symmetry and has the extended all-trans conformation. The dihydrogendiphosphate anion is located on a twofold axis with the bridge P--O---P angle 134.26 (7) ° and the two PO3 groups staggered about the P...P axis. The ions are H bonded into two-dimensional layers perpendicular to b with no H bonding between the layers.
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