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NHN+ and NHN− hydrogen bonds in the adducts of 1,8-bis(dimethylamino)naphthalene with 1,8-bis(trifluoroacetamido)naphthalene and 1,8-bis(4-toluenesulphonamido)-2,4,5,7-tetranitronaphthalene
Journal of
MOLECULAR STRUCTURE ELSEVIER
Journal of Molecular Structure 327 (1994) 71-79
NHN+ and NHN- hydrogen bonds in the adducts of 1,8bis(dimethylamino)naphthalene with 1,8bis(trifluoroacetamido)naphthalene and 1&bis(4toluenesulphonamido)-2,4,5,7-tetranitronaphthalene Bogumil Brzezifiskia, Eugeniusz Grechb, Joanna Nowicka-Scheibeb, Tadeusz Glowiakc, Zbigniew Malarskic, Lucjan Sobczykc>* ‘Faculty of Chemistry, A. Mickiewicz University, 60-780 Poznari, Poland bInstitute of Fundamental Chemistry, Technical University, 71-065 Szczecin. Poland ‘Institute of Chemistry, University of Wrociaw, 50-383 Wroclaw, Poland
First received 21 April 1994; in final form 11 May 1994
Abstract
The crystal structure of the adduct of 1,8-bis(dimethylamino)naphthalene (DMAN) with l$-bis(tritluoroacetamido)naphthalene (TFAN) was determined from X-ray diffraction studies. The crystal of DMAN - TFAN are monoclinic, space group C’2/c, with a = 20.181(4), b = 17.068(4), c = 18.333(4)& /I = 122.64(4)0 and Z = 8. The NHN- hydrogen bond formed after the abstraction of the proton from TFAN is 2.608(4) A long with (NHN equal to 138(3)“. Remarkable symmetrization of the anion takes place although the bridge H-atom is localized closer to one nitrogen atom. ‘H NMR and IR studies in acetonitrile show that the ion pairs formed in the systems DMAN-TFAN and DMAN-TSATNN (1,8-bis(4-toluenesulphonamido)-2,4,5,7-tetranitronaphthalene) are very stable and that the NHN- hydrogen bonds in DMAN - TFAN are slightly stronger than those in DMAN - TSATNN.
1. Introduction In previous papers we studied protonation reactions of l,fGbis(dimethylamino)naphthalene (DMAN) and other proton sponges with inorganic acids [l-4], phenols [4-61, N-H acids [7], C-H acids [8,9] and S-H proton donors [lo]. For all reactions, with the exception of C-H and S-H acids, protonated DMAN and homoconjugated OHO- or NHN- anions have been detected in acetonitrile solution.
The protonation of DMAN with compounds containing acidic N-H groups yielded homoconjugated NHN- anions which are very difficult to obtain in other reactions. In this way numerous intermolecular NHN- hydrogen bonds with aromatic N-H acids were obtained. The IR spectra of such bonds in the imidazoleimidazolate system [7] showed a broad absorption beginning at 3000cm-’ and extending toward smaller wavenumbers. In the region of higher wavenumbers this absorption shows two maxima centred at about 1950 and 2500 cm-‘. This spectral feature is similar to those usually observed for
0022-2860/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDI 0022-2860(94)08349-M
B. Brzeziriski et al/J. Mol. Struct. 327 (1994) 71-79
72
H&
DMAN
TFAN
FH3
TSATNN
Scheme 1.
strong NHN+ hydrogen bonds of aromatic N-bases [ 111. The IR spectra of NHN- bonds formed by aliphatic N-acids showed intense “continua”, which depended on steric conditions [12,13].
When the NHN- bridge was bent substantially, the IR spectrum showed a band-like structure in the region 3000- 1800 cm-’ [ 131. A very similar observation was made in the IR spectrum of a complex of DMAN with 1,8-bis(4-toluenesulphonamide)-2,4,5,7_tetranitronaphthalene (TSATNN) in the solid state [14]. For the first time the X-ray structure of the intramolecular NHN- bridge which is formed after the abstraction of the proton from TSATNN was determined. The NHN- hydrogen bridge appeared to be fairly short (RN...N= 2.600(5)& (NHN = 153(5)“) and comparable with the cationic NHN+ bridges. Simultaneously the absorption band v,(NHN) was located at relatively high frequencies (maximum at 2750 cm’). In this paper we report X-ray diffraction studies on another complex with an intramolecular NHNhydrogen bridge, namely that formed between
Table 1 Crystal data, data collection details and refinement Formula W a(A) b(A) c(A) !R) Space group t (000) (e) T (K) 25 of ref. to determine cell constants, range (28) D, (flotation CHsClCHrCl/CC&) (Mgm-‘) 0, (Mgm-‘) x(A) MoK, Monochromator crystal size (mm) Linear absorption coefhcient (cm-‘) Data collection method Number of standard reflections Variation in standard retlections (%) Number of unique reflections with I > 30(Z) Variable parameters Final R, = [c w(]Fo] Final S = [c w(]Fo] Function minimized (w = l/ Final A/u for non-H atoms for H atoms Final Ap (e A’)
W-bN
*Cd&F&02
564.5 20.181(4) 17.068(4) 18.333(4) 122.64(4) 5318(3) c2/c 8 2336 296 20-26” 1.42(l) 1.410(l) 0.71069 Graphite 0.40 x 0.45 x 0.55 1.30 w/0 scan 3/100 4 2765 465 0.052 0.046 2.801 c “0l.y - IW2 0.05 0.39
13
B. Brzeziriski et al./J, Mol. Strut. 327 (1994) 71-79 Table 2 Atomic positions (fractional coordinates) and thermal parameters with standard deviations in parenthesesa Atom
F(21) V22) ~(23) w24) F(25) F(26) O(21) (x22) Wll) Nl2) N(21) N(22) C(l1) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(110) C(111) C(112) C( 113) C(l14) C(21) C(22) ~(23) ~(24) C(25) C(26) ~(27) C(28) C(29) C(210) C(211) C(212) C(213) C(214) H(1) H(2) H(3) H(4) H(5) H(6) H(7) H(8) H(9) WlO) Wll)
x 0.4062(2) 0.4917(2) 0.3814(2) 0.2462(2) 0.2092(3) 0.1404(2) 0.4152(2) 0.071 l(2) 0.3810(2) 0.4069(2) 0.3352(2) 0.1901(2) 0.3781(2) 0.3637(2) 0.3605(2) 0.3720(2) 0.3987(2) 0.4128(2) 0.4170(2) 0.4049(2) 0.3899(2) 0.3869(2) 0.4463(2) 0.3047(2) 0.4828(2) 0.3382(2) 0.3088(2) 0.3604(2) 0:3363(3) 0.2590(2) 0.1239(2) 0.0699(2) 0.0903(2) 0.1674(2) 0.2274(2) 0.2038(2) 0.3870(2) 0.4149(2) 0.1419(2) 0.1839(3) 0.398(2) 0.247(2) 0.358(2) 0.348(2) 0.367(l) 0.397(2) 0.420(2) 0.425(2) 0.451(2) 0.435(2) 0.500(Z)
Y 0.5742(2) 0.6244(2) 0.6765(l) 0.5858(2) 0.6744(2) 0.6428(3) 0.5841(2) 0.5606(2) 0.3684( 1) 0.2500(2) 0.5089(2) 0.51740) 0.3145(2) 0.3420(2) 0.2899(2) 0.2124(2) 0.0998(2) 0.0701(2) 0.1201(2) 0.1989(2) 0.2333(2) 0.1811(2) 0.4260(2) 0.4082(2) 0.2469(2) 0.2355(2) 0.4579(2) 0.4249(2) 0.3710(2) 0.3487(2) 0.3561(2) 0.3847(2) 0.4386(2) 0.4635(2) 0.4352(2) 0.3798(2) 0.5632(2) 0.6085(2) 0.5597(2) 0.6121(3) 0.314(2) 0.527(2) 0.399(2) 0.304(2) 0.178(2) 0.064(2) 0.012(2) 0.097(2) 0.458(2) 0.463(2) 0.394(2)
2 0.2232(2) 0.3425(2) 0.2668(2) 0.0723(2) 0.1149(3) -0.0096(2) 0.4167(2) 0.0484(2) 0.0695(2) O.OOOO(2) 0.2940(2) 0.1623(2) 0.1301(2) 0.1903(2) 0.2476(2) 0.2441(2) 0.1793(2) 0.1205(3) 0.0624(2) 0.0633(2) 0.1237(2) 0.1831(2) 0.1134(2) 0.0119(3) 0.0049(2) -0.0897(2) 0.3341(2) 0.4141(2) 0.4510(2) 0.4093(2) 0.2848(3) 0.2063(3) 0.1645(2) 0.2041(2) 0.2877(2) 0.3278(2) 0.3408(2) 0.2917(3) 0.0917(2) 0.0645(3) 0.023(2) 0.191(2) 0.195(2) 0.288(2) 0.279(2) 0.220(2) 0.118(2) 0.018(2) 0.068(2) 0.150(2) 0.155(2)
Table 2 (continued) Atom
&(AZ)b
WW
8.8(l) 12.2(2) 11.1(2) 13.3(2) 16.3(2) 16.6(2) 7.5(l) 8.9(2) 4.1(l) 3.9(l) 4.7(l) 4.6(l)
Wl3) Wl4) Wl5) Wl6) Wl7) Wl8) Wl9) H(20) W21) W22) ~(23) ~(24) ~(25) W26)
4.00) 5.0(2) 5.7(2) 5.5(2) 5.6(2) 5.8(2) 4.9(l) 4.0(l) 3.9(l) 4.5(l) 5.9(2) 6.1(2) 5.1(2) 5.4(2) 4.4(l) 5.4(2) 6.4(2) 6.1(2) 6.1(2) 6.2(2) 5.2(2) 4.5(l) 4.4(l) 5.2(2) 4.9(l) 6.3(2) 5.4(2) 7.6(2) 6.6(8) 7.6(9) 5.1(7) 6.1(8) 4.6(6) 7.3(9) lO.O(ll) 5.9(8) 7.4(9) 8.6(10) 8.0(9)
x
Y
Z
0.290(2) 0.264(2) 0.31 l(2) 0.481(2) 0.527(2) 0.492(2) 0.337(2) 0.287(2) 0.345(2) 0.417(2) 0.369(2) 0.238(2) 0.107(2) 0.018(2) 0.049(2)
0.449(2) 0.369(2) O&1(2) 0.291(2) 0.261(2) 0.193(2) 0.273(2) 0.243(2) 0.184(2) 0.441(2) 0.350(2) 0.305(2) 0.315(2) 0.366(2) 0.455(2)
0.043(2) -0.012(2) -0.022(2) -0.035(2) 0.069(2) -0.017(2) -0.131(2) -0.093(2) -0.107(2) 0.445(2) 0.508(2) 0.434(2) 0.313(2) 0.177(2) 0.105(2)
B,@2)b
7.9(9) 7.2(9) 8.2(10) 6.4(8) 7.5(9) 8.0(9) 5.8(8) 6.7(10) 8.3(10) 5.2(7) 6.9(9) 8.6(10) 7.6(9) 6.9(9) 5.1(7)
’ Biso for hydrogen atoms. b Beg = f C C Bijaiaja;aJ i
j
DMAN and 1,8-bis(trifluoroacetamido)naphthalene (TFAN) . This paper also reports the results of ‘H NMR and FT-IR studies on both complexes @MAN. TFAN and DMAN - TSATNN) in acetonitrile solutions. FT-IR spectroscopy allowed us to distinguish and separate from the complex spectra the absorption characteristic of the NHN- bridge and to compare it with the absorption of intramolecular aliphatic NHN+ hydrogen bridges and the NHN- bridge in the solid state.
2. Experimental DMAN purchased from Aldrich was used after double recrystallization from ethanol. TSATNN and TFAN were synthesized following the procedures given in [ 151 and [ 161. Spectroscopic-grade acetonitrile and acetonitrileds were dried over 3 A molecular sieves. The 1 : 1 complexes of DMAN with TSATNN or TFAN were obtained by dissolving eqttimolar amounts of the corresponding acid in a 0.1 mol dmm3 acetonitrile solution of DMAN. The space group and approximate unit-cell dimensions were determined from rotation and Weissenberg photographs. The diffraction data
74
B. Brzezihki
ei al.iJ. Mol. Struct. 327 (1994) 71-79
M23)
IBM PC/AT computers. Neutral atomic scattering factors for all atoms were taken from [19]. The scattering factors for non-hydrogen atoms were corrected for real and imaginary components. The positions of all hydrogen atoms were determined from difference Fourier synthesis and refined isotropically. IR spectra were recorded in acetonitrile on an FT-IR Bruker IFA 113 v spectrophotometer. A cell with silicon windows and a wedge-shaped layer was used to avoid interference (mean layer thickness, 0.26mm). IR spectra of the solid adduct were recorded on a Perkin-Elmer 180 spectrophotometer. ‘H NMR spectra were recorded in acetonitriled3 at room temperature using a Varian Gemino VT 300 spectrometer at 300MHz using tetramethylsilane as the internal standard.
3. Results and discussion 3.1. The crystal and molecular structure of DMAN- TFAN
c(24) ‘cs9
Fig. 1. Molecular structure and atom numbering of cationic and anionic groups of the DMAN . TFAN adduct.
were collected by MoK, radiation using a KUMA four-circle K-axis computer-controlled KM4 diffractometer. Details of the diffraction experiments, the crystal data collection and refinement are given in Table 1. The intensities were corrected for Lorentz and polarization effects, but not for extinction or absorption. The structure was solved by direct methods using the program SHELXS 86 [17], and refined by the fullmatrix least-squares technique using the Syntex XTL/XTLE structure determination system [ 181 locally adapted by Kowalski for calculation on
The atomic positions (fractional coordinates) in the DMAN - TFAN crystal are collected in Table 2. The atom numbering in protonated DMAN and deprotonated TFAN is shown in Fig. 1, while the important bond lengths and angles are listed in Table 3. In the crystalline lattice the cations and anions are almost oriented perpendicularly (90.1”) with respect to each other. The structure of the cation is close to that reported already in many papers [14, 20-251. In this instance it is almost symmetric although the bridge H-atom is located closer to the N(12) nitrogen atom (&(ii)_H = 1.42(3), &(tZ)-H = 1.22(3), RN(I1)-N(lz) = 2.588(4) A and (NllHN12 = 156(3”)). As a consequence, there are some differences in the bond lengths of the two moieties of the naphthalene skeleton (the maximum deviation from planarity is 0.010 A). The NHN- hydrogen bridges in the anions are asymmetric. The distances of the H-atom from the nitrogen atoms are 0.99(4) and 1.79(3)A. The bridge is significantly bent, (NHN being 138(3)“. The asymmetry of the bridge is only slightly
B. Brzeziriski et al./J. Mol. Struet. 327 (1994)
Table 3 (continued)
Table 3 Interatomic distances and angles
Distance (A) Distance (A) F(21)-C(212) F(22)-C(212) F(23)-C(212) F(24)-C(214) F(25)-C(214) F(26)-C(214) 0(21)-C(211) 0(22)-C(213) N(11). . . N(12) N(l I)-C(11) N(l I)-C(11 1) N(ll)-C(112) N(11). H(1) N(12)-C(18) N(12)-C(113) N(12)-C(114) N(12)-H(1) N(21). .N(22) N(21)-C(21) N(21)-C(211) N(21). H(2) N(22)-C(28) N(22)-C(213) N(22)-H(2) C(ll)-C(12) C(ll)-C(19) C(12)-C(13) C(13)-C(14) C(14)-C(110) C(llO-C(15) C(1 lO)-C(19) C(15)-C(16) C(16)-C(17) C(17)-C(18) C(18)-C(19) C(21)-C(22) C(21)-C(29) C(22)-C(23) C(23)-C(24) C(24)-C(210) C(210)-C(25) C(210)-C(29) C(25)-C(26) C(26)-C(27) C(27)-C(28) C(28)-C(29) C(211)-C(212) C(213)-C(214)
75
71-79
Angles (deg.)
Angles (deg.) 1.308(5) 1.337(6) 1.295(5) 1.268(7) 1.317(5) 1.267(5) 1.237(4) 1.204(6) 2.588(4) 1.468(4) 1.486(5) 1.481(5) 1.42(3) 1.469(4) 1.486(6) 1.492(4) 1.22(3) 2.608(4) 1.416(5) 1.312(5) 1.79(3) 1.423(5) 1.336(4) 0.99(4) 1.366(5) 1.422(4) l&4(5) 1.351(5) 1.410(6) 1.415(5) 1.433(5) 1.352(6) 1.403(5) 1.368(4) 1.423(5) 1.381(5) 1.437(6) 1.377(6) 1.370(7) 1.401(5) 1.419(7) 1.427(5) 1.344(6) 1.394(6) 1.382(6) 1.432(5) 1.508(6) 1.490(7)
C(1 I)-N(l I)-C(l 11) C(ll)-N(l I)-C(112) C(l I)-N(ll)-H(1) C(18)-N(12)-C(113) C(18)-N(12)-C(114) C(18)-N(12)-H(1) C(21)-N(21)-C(211) C(21)-N(21)-H(2) C(21 l)-N(21)-H(2) C(28)-N(22)-C(213) C(28)-N(22)-H(2) C(213)-N(22)-H(2) N(l I)-C(1 l)-C(12) N(ll)-C(ll)-C(19) C(12)-C(1 l)-C(19) C(ll)-C(12)-C(13) C(12)-C(13)-C(14) c(13)-c(14)-c(110) c(14)-c(11o)-c(15) c(14)-c(11o)-c(19) c(15)-c(11o)-c(19) C(llO)-C(15)-C(16) C(15)-C(16)-C(17) C(16)-C(17)-C(18) N(12)-C(18)-C(17) N(12)-C(18)-C(19) C(17)-C(18)-C(19) c(11)-c(19)-c(110) C(ll)-C(19)-C(18) C(llO)-C(19)-C(18) N(21)-C(21)-C(22) N(21)-C(21)-C(29) C(22)-C(21)-C(29) C(21)-C(22)-C(23) C(22)-C(23)-C(24) C(23)-C(24)-C(210) C(24)-C(210)-C(25) C(24)-C(210)-C(29) C(25)-C(210)-C(29) C(210-C(25)-C(26) C(25)-C(26)-C(27) C(26)-C(27)-C(28) N(22)-C(28)-C(27) N(22)-C(28)-C(29) C(27)-C(28)-C(29) C(21)-C(29)-C(210) C(21)-C(29)-C(28) C(210)-C(29)-C(28) 0(21)-C(21 l)-N(21) 0(21)-C(21 l)-C(212) N(21)-C(211)-C(212) 0(22)-C(213)-N(22)
113.0(3) 112.2(3) 100(l) 113.4(3) 111.5(3) lOl(2) 119.0(3) 102(l) 124(l) 126.4(3) 116(2) 117(2) 120.5(3) 118.1(3) 121.3(3) 120.1(4) 120.4(4) 121.7(4) 121.6(4) 118.7(3) 119.6(3) 121.3(4) 120.1(4) 120.3(4) 119.6(3) 118.5(3) 121.9(3) 117.8(3) 125.6(3) 116.7(3) 121.4(3) 119.3(3) 119.1(3) 122.0(4) 120.7(4) 120.0(4) 119.8(4) 120.4(4) 119.8(4) 120.9(4) 121.3(4) 119.8(4) 121.0(3) 117.6(3) 121.4(3) 117.8(3) 125.4(3) 116.8(3) 131.3(4) 115.4(4) 113.2(3) 129.1(4)
0(22)-C(213)-C(214) N(22)-C(213)-C(214) N(ll)-H(l)-N(12) N(21)-H(2)-H(22)
117.4(4) 113.5(4) 156(3) 138(3)
reflected in the geometry of the adjacent groups. Thus the C&- N bond lengths are almost identical. More pronounced differences appear in the trifluoroacetyl groups: rcN = 1.312(5) and 1.336(4), and rco = 1.237(4) and 1.204(6) A. There is a marked difference in the orientation of the trifluoroacetyl groups with respect to the naphthalene plane. The amide groups are planar but not co-planar with the naphthalene skeleton. The normals to the amide and naphthalene planes form the angles 135.1 and 11.1‘, respectively. The NHN hydrogen-bond length in deprotonated TFAN (2.608(4)& is almost the same as in deprotonated TSATNN [14] although the electronic state of the bridge atoms is substantially different. For TFAN the C&-N bond lengths (1.416(5), 1.423(5) A) indicate a hybrydization intermediate between sp2 and sp3 but closer to sp3. For TSATNN, however, these bonds are markedly shorter and differentiated (1.397(7) and 1.336(6)A). The electronic state of the nitrogen atoms N(4) becomes closer to sp2. Simultaneously strong asymmetric location of the H-atom is evidenced. This is why the NHN- bridge in deprotonated TFAN is stronger than in deprotonated TSATNN in spite of the fact that the bridges are of the same length. It should be remembered that in the protonated proton sponge DMAN the hybridization state of the nitrogen atoms is close to sp3 and the hydrogen bonds therein are stronger. 3.2. ‘H NMR spectra in acetonitrile The ‘H NMR data corresponding to the cation and anion are collected in Table 4. The chemical shift of the bridge proton in protonated DMAN is identical with that previously reported [2]. The chemical shifts of the other protons and splittings of the CH3 signals caused by the couplings with the bridge protons are also similar [2,3].
18.63 18.61
+ HNOja + TFAN
+ TSATNN
DMAN DMAN
DMAN
(J = 9.0).
18.66
_ 18.92
a Ref. [2] b Ref. [3]. ’ d = doublet
with HN09,
7.87
7.80
6.93 7.94
H-2,7
7.68
7.62
7.25 7.70
H-3,6
8.01
7.98
7.32 8.04
H-4,5
3.04, 3.03 3.09, 3.08
2.75 3.14
CHS
7.6
7.7
7.2 7.8
J(2,3)
8.1
8.3
7.8 8.4
J(3,4)
1.0
0.9
1.8 0.9
J(2,4)
15.16
16.42
_ -
NHN-
and its complexes
NHN+
(Hz) of DMAN Anion
constants
Cation
shifts @pm) and coupling
DMANa DMAN + HN03b
Compound
Table 4 ‘H NMR chemical
-
7.32
_ _
H-2,7
TFAN
8.74
7.45
_
H-3,6
-
8.46
_
H-4,5
and TSATNN
2.37, 2.32
-
-
CH3
7.74d, 7.62dc
-
-
Ph rings
-
7.7
-
J(2,3)
-
8.3
-
J(3,4)
-
0.9
-
J(2,4)
B. Brzezitiski et al./J. Mol. Struct. 327 (1994)
71-79
WAVENUMBER [l/CM] Fig. 2. IR spectra of (- - -) DMAN and (-)
There is no exchange of protons between the cation and anion, at least on the NMR time scale. The signals from the NHN- bridge protons correspond to lower chemical shift values than the cation. Comparing the those of DMAN - TFAN and DMAN . TSATNN systems, one can conclude that the hydrogen bonding in deprotonated TFAN is stronger than that in deprotonated TSATNN in accordance with IR spectra, which will be discussed later. In the TSATNN anion two closely located CHs signals are observed. The origin of the splitting is not clear. In the crystalline lattice of DMANeTSATNN the two tolyl groups occupy different positions [14]. One can suppose that the situation in solution is similar. However, exchange between two positions followed by the jumping of
its 1 : 1 complexes with: TSATNN (a); TFAN (b).
the bridge proton is probably too fast on the NMR time scale. The two moieties of the naphthalene ring are identical (one signal from protons in positions 3,6). 3.3. IR spectra In the IR spectra of the DMAN complexes both with TFAN and TSATNN absorption “continua” are visible, which extend from about 3200 cm-’ up to at least 4OOcm-’ (Fig. 2). Complete protonization of DMAN takes place which is reflected in the vanishing of Bohlmann bands of the methyl groups attached to the nitrogen atoms. As has been shown previously [1,4-71, the DMAN - H+ cations in acetonitrile absorb over a broad frequency range so that it seemed necessary to
B. Brzezihki et al./J. Mol. Struct. 327 (1994) 71-79
I
. %ooo
3000
3500
,
2500
~~ 1500
2000
WAVENUMBER
1000
500
[l/CM]
Fig. 3. IR difference spectra of 1 : 1 complexes of DMAN with TSATNN (a) and TFAN (b). The DMAN tetrachloroaurate absorption is used as a reference.
,tNti~I+
I
3000
I
2500
I
2000 g/cm-’
”
I
I
600
400
Fig. 4. IR spectra of the solid DMAN - TFAN adduct in Nujol and fluoroluble oil at room (. .) and liquid-nitrogen temperature (-).
B. Brzezihki
et al/J. Mol. Struct. 327 (1994)
separate the absorption of this cation by means of difference spectra. The absorption of DMAN chloroaurate was used as a reference absorption. The difference spectra are shown in Fig. 3. It can be seen that the anionic NHN- bridges give rise to broad but localized V, protonic bands at about 28OOcrK’ (TSATNN) and 275Ocm-’ (TFAN). Both the position and width of the bands indicate that the NHN- bridge in deprotonated TFAN is somewhat stronger than that in deprotonated TSATNN in accordance with the NMR spectra. In the solid-state DMAN-TFAN system the bands ascribed to the NHN+ and NHN- bridges are well separated as shown in Fig. 4. The same is true for the DMAN-TSATNN ion pair [14]. As expected, the v,(NHN-) bands in the solid state are shifted to slightly lower frequencies. The corresponding maxima are located at 272Ocm-’ (TSATNN) and 2640 cm-’ (TFAN). References [l] B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Faraday Trans., 86 (1990) 1777. [2] B. Brycki, B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, Magn. Reson. Chem., 29 (1991) 558. [3] Z. Dega-Szafran, B. Nowak-Wydra and M. Szafran, Magn. Reson. Chem., 31 (1993) 726. [4] B. Brzezinski, T. Glowiak, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 1643; Croat. Chem. Acta, 65 (1992) 101. [5] B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 857. [6] B. Brzezinski, G. Schroeder, E. Grech, Z. Malarski and L. Sobczyk, J. Mol. Struct., 274 (1992) 75.
71-79
79
[7l B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 1267. [8] B. Brzezinski, A. Jarczewski, J. Olejnik and G. Schroeder, J. Chem. Sot., Perkin Trans. 2, (1992) 2257. [9] G. Schroeder, B. Brzezinski and A. Jarczewski, J. Mol. Struct., 274 (1992) 83. WI B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, Pol. J. Chem., 68 (1994) 261. Pll E. Grech, Z. Malarski and L. Sobczyk, Pol. J. Chem., 52 (1978) 131. WI D. Schioberg and G. Zundel, J. Chem. Sot., Faraday Trans 2, 69 (1973) 771. [I31 B. Brzezinski and G. Zundel, J. Chem. Sot., Faraday Trans. 2, 79 (1983) 1249. 1141Z. Malarski, T. Lis, E. Grech, J. Nowicka-Scheibe and K. Majewska, J. Mol. Struct., 221 (1990) 227. 1151F. Hibbert and M.A. Malana, J. Chem. Sot., Perkin Trans. 2, (1992) 755. Ml H.H. Hodgson and J.S. Whitehurst, J. Chem. Sot., (1947) 80. 1171G.M. Sheldrick, SHELXS 86,Program for Crystal Structure Solution, University of Gottingen, Germany, 1986. WI Syntex XTL/XTLE Structure Determination System, Syntex Analytical Instruments, Cupertino, CA, 1976. 1191International Tables for X-ray Crystallography, Vol. IV, Kynoch Press, Birmingham, 1974. PO1 D. Pyialska, R. Pyialski and T. Borowiak, J. Crystallogr. Spectrosc. Res., 13 (1983) 211. PI T. Giowiack, Z. Malarski, L. Sobczyk and E. Grech, J. Mol. Struct., 157 (1987) 329. PI K. Wozniak, T.M. Krygowski, B. Kariuki, W. Jones and E. Grech, J. Mol. Struct., 240 (1990) 111. 1231J.A. Kanters, A. Schouten, A.J.M. Duisenberg, T. Glowiak, Z. Malarski, L. Sobczyk and E. Grech, Acta Crystallogr., Sect. C, 47 (1991) 2148. 1241J.A. Kanters, A. Schouten, J. Kroon and E. Grech, Acta Crystallogr., Sect. C, 47 (1991) 807. ~251T. GIowiak, E. Grech, Z. Malarski and L. Sobczyk, J. Mol. Struct., 295 (1993) 105.
MOLECULAR STRUCTURE ELSEVIER
Journal of Molecular Structure 327 (1994) 71-79
NHN+ and NHN- hydrogen bonds in the adducts of 1,8bis(dimethylamino)naphthalene with 1,8bis(trifluoroacetamido)naphthalene and 1&bis(4toluenesulphonamido)-2,4,5,7-tetranitronaphthalene Bogumil Brzezifiskia, Eugeniusz Grechb, Joanna Nowicka-Scheibeb, Tadeusz Glowiakc, Zbigniew Malarskic, Lucjan Sobczykc>* ‘Faculty of Chemistry, A. Mickiewicz University, 60-780 Poznari, Poland bInstitute of Fundamental Chemistry, Technical University, 71-065 Szczecin. Poland ‘Institute of Chemistry, University of Wrociaw, 50-383 Wroclaw, Poland
First received 21 April 1994; in final form 11 May 1994
Abstract
The crystal structure of the adduct of 1,8-bis(dimethylamino)naphthalene (DMAN) with l$-bis(tritluoroacetamido)naphthalene (TFAN) was determined from X-ray diffraction studies. The crystal of DMAN - TFAN are monoclinic, space group C’2/c, with a = 20.181(4), b = 17.068(4), c = 18.333(4)& /I = 122.64(4)0 and Z = 8. The NHN- hydrogen bond formed after the abstraction of the proton from TFAN is 2.608(4) A long with (NHN equal to 138(3)“. Remarkable symmetrization of the anion takes place although the bridge H-atom is localized closer to one nitrogen atom. ‘H NMR and IR studies in acetonitrile show that the ion pairs formed in the systems DMAN-TFAN and DMAN-TSATNN (1,8-bis(4-toluenesulphonamido)-2,4,5,7-tetranitronaphthalene) are very stable and that the NHN- hydrogen bonds in DMAN - TFAN are slightly stronger than those in DMAN - TSATNN.
1. Introduction In previous papers we studied protonation reactions of l,fGbis(dimethylamino)naphthalene (DMAN) and other proton sponges with inorganic acids [l-4], phenols [4-61, N-H acids [7], C-H acids [8,9] and S-H proton donors [lo]. For all reactions, with the exception of C-H and S-H acids, protonated DMAN and homoconjugated OHO- or NHN- anions have been detected in acetonitrile solution.
The protonation of DMAN with compounds containing acidic N-H groups yielded homoconjugated NHN- anions which are very difficult to obtain in other reactions. In this way numerous intermolecular NHN- hydrogen bonds with aromatic N-H acids were obtained. The IR spectra of such bonds in the imidazoleimidazolate system [7] showed a broad absorption beginning at 3000cm-’ and extending toward smaller wavenumbers. In the region of higher wavenumbers this absorption shows two maxima centred at about 1950 and 2500 cm-‘. This spectral feature is similar to those usually observed for
0022-2860/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDI 0022-2860(94)08349-M
B. Brzeziriski et al/J. Mol. Struct. 327 (1994) 71-79
72
H&
DMAN
TFAN
FH3
TSATNN
Scheme 1.
strong NHN+ hydrogen bonds of aromatic N-bases [ 111. The IR spectra of NHN- bonds formed by aliphatic N-acids showed intense “continua”, which depended on steric conditions [12,13].
When the NHN- bridge was bent substantially, the IR spectrum showed a band-like structure in the region 3000- 1800 cm-’ [ 131. A very similar observation was made in the IR spectrum of a complex of DMAN with 1,8-bis(4-toluenesulphonamide)-2,4,5,7_tetranitronaphthalene (TSATNN) in the solid state [14]. For the first time the X-ray structure of the intramolecular NHN- bridge which is formed after the abstraction of the proton from TSATNN was determined. The NHN- hydrogen bridge appeared to be fairly short (RN...N= 2.600(5)& (NHN = 153(5)“) and comparable with the cationic NHN+ bridges. Simultaneously the absorption band v,(NHN) was located at relatively high frequencies (maximum at 2750 cm’). In this paper we report X-ray diffraction studies on another complex with an intramolecular NHNhydrogen bridge, namely that formed between
Table 1 Crystal data, data collection details and refinement Formula W a(A) b(A) c(A) !R) Space group t (000) (e) T (K) 25 of ref. to determine cell constants, range (28) D, (flotation CHsClCHrCl/CC&) (Mgm-‘) 0, (Mgm-‘) x(A) MoK, Monochromator crystal size (mm) Linear absorption coefhcient (cm-‘) Data collection method Number of standard reflections Variation in standard retlections (%) Number of unique reflections with I > 30(Z) Variable parameters Final R, = [c w(]Fo] Final S = [c w(]Fo] Function minimized (w = l/ Final A/u for non-H atoms for H atoms Final Ap (e A’)
W-bN
*Cd&F&02
564.5 20.181(4) 17.068(4) 18.333(4) 122.64(4) 5318(3) c2/c 8 2336 296 20-26” 1.42(l) 1.410(l) 0.71069 Graphite 0.40 x 0.45 x 0.55 1.30 w/0 scan 3/100 4 2765 465 0.052 0.046 2.801 c “0l.y - IW2 0.05 0.39
13
B. Brzeziriski et al./J, Mol. Strut. 327 (1994) 71-79 Table 2 Atomic positions (fractional coordinates) and thermal parameters with standard deviations in parenthesesa Atom
F(21) V22) ~(23) w24) F(25) F(26) O(21) (x22) Wll) Nl2) N(21) N(22) C(l1) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(110) C(111) C(112) C( 113) C(l14) C(21) C(22) ~(23) ~(24) C(25) C(26) ~(27) C(28) C(29) C(210) C(211) C(212) C(213) C(214) H(1) H(2) H(3) H(4) H(5) H(6) H(7) H(8) H(9) WlO) Wll)
x 0.4062(2) 0.4917(2) 0.3814(2) 0.2462(2) 0.2092(3) 0.1404(2) 0.4152(2) 0.071 l(2) 0.3810(2) 0.4069(2) 0.3352(2) 0.1901(2) 0.3781(2) 0.3637(2) 0.3605(2) 0.3720(2) 0.3987(2) 0.4128(2) 0.4170(2) 0.4049(2) 0.3899(2) 0.3869(2) 0.4463(2) 0.3047(2) 0.4828(2) 0.3382(2) 0.3088(2) 0.3604(2) 0:3363(3) 0.2590(2) 0.1239(2) 0.0699(2) 0.0903(2) 0.1674(2) 0.2274(2) 0.2038(2) 0.3870(2) 0.4149(2) 0.1419(2) 0.1839(3) 0.398(2) 0.247(2) 0.358(2) 0.348(2) 0.367(l) 0.397(2) 0.420(2) 0.425(2) 0.451(2) 0.435(2) 0.500(Z)
Y 0.5742(2) 0.6244(2) 0.6765(l) 0.5858(2) 0.6744(2) 0.6428(3) 0.5841(2) 0.5606(2) 0.3684( 1) 0.2500(2) 0.5089(2) 0.51740) 0.3145(2) 0.3420(2) 0.2899(2) 0.2124(2) 0.0998(2) 0.0701(2) 0.1201(2) 0.1989(2) 0.2333(2) 0.1811(2) 0.4260(2) 0.4082(2) 0.2469(2) 0.2355(2) 0.4579(2) 0.4249(2) 0.3710(2) 0.3487(2) 0.3561(2) 0.3847(2) 0.4386(2) 0.4635(2) 0.4352(2) 0.3798(2) 0.5632(2) 0.6085(2) 0.5597(2) 0.6121(3) 0.314(2) 0.527(2) 0.399(2) 0.304(2) 0.178(2) 0.064(2) 0.012(2) 0.097(2) 0.458(2) 0.463(2) 0.394(2)
2 0.2232(2) 0.3425(2) 0.2668(2) 0.0723(2) 0.1149(3) -0.0096(2) 0.4167(2) 0.0484(2) 0.0695(2) O.OOOO(2) 0.2940(2) 0.1623(2) 0.1301(2) 0.1903(2) 0.2476(2) 0.2441(2) 0.1793(2) 0.1205(3) 0.0624(2) 0.0633(2) 0.1237(2) 0.1831(2) 0.1134(2) 0.0119(3) 0.0049(2) -0.0897(2) 0.3341(2) 0.4141(2) 0.4510(2) 0.4093(2) 0.2848(3) 0.2063(3) 0.1645(2) 0.2041(2) 0.2877(2) 0.3278(2) 0.3408(2) 0.2917(3) 0.0917(2) 0.0645(3) 0.023(2) 0.191(2) 0.195(2) 0.288(2) 0.279(2) 0.220(2) 0.118(2) 0.018(2) 0.068(2) 0.150(2) 0.155(2)
Table 2 (continued) Atom
&(AZ)b
WW
8.8(l) 12.2(2) 11.1(2) 13.3(2) 16.3(2) 16.6(2) 7.5(l) 8.9(2) 4.1(l) 3.9(l) 4.7(l) 4.6(l)
Wl3) Wl4) Wl5) Wl6) Wl7) Wl8) Wl9) H(20) W21) W22) ~(23) ~(24) ~(25) W26)
4.00) 5.0(2) 5.7(2) 5.5(2) 5.6(2) 5.8(2) 4.9(l) 4.0(l) 3.9(l) 4.5(l) 5.9(2) 6.1(2) 5.1(2) 5.4(2) 4.4(l) 5.4(2) 6.4(2) 6.1(2) 6.1(2) 6.2(2) 5.2(2) 4.5(l) 4.4(l) 5.2(2) 4.9(l) 6.3(2) 5.4(2) 7.6(2) 6.6(8) 7.6(9) 5.1(7) 6.1(8) 4.6(6) 7.3(9) lO.O(ll) 5.9(8) 7.4(9) 8.6(10) 8.0(9)
x
Y
Z
0.290(2) 0.264(2) 0.31 l(2) 0.481(2) 0.527(2) 0.492(2) 0.337(2) 0.287(2) 0.345(2) 0.417(2) 0.369(2) 0.238(2) 0.107(2) 0.018(2) 0.049(2)
0.449(2) 0.369(2) O&1(2) 0.291(2) 0.261(2) 0.193(2) 0.273(2) 0.243(2) 0.184(2) 0.441(2) 0.350(2) 0.305(2) 0.315(2) 0.366(2) 0.455(2)
0.043(2) -0.012(2) -0.022(2) -0.035(2) 0.069(2) -0.017(2) -0.131(2) -0.093(2) -0.107(2) 0.445(2) 0.508(2) 0.434(2) 0.313(2) 0.177(2) 0.105(2)
B,@2)b
7.9(9) 7.2(9) 8.2(10) 6.4(8) 7.5(9) 8.0(9) 5.8(8) 6.7(10) 8.3(10) 5.2(7) 6.9(9) 8.6(10) 7.6(9) 6.9(9) 5.1(7)
’ Biso for hydrogen atoms. b Beg = f C C Bijaiaja;aJ i
j
DMAN and 1,8-bis(trifluoroacetamido)naphthalene (TFAN) . This paper also reports the results of ‘H NMR and FT-IR studies on both complexes @MAN. TFAN and DMAN - TSATNN) in acetonitrile solutions. FT-IR spectroscopy allowed us to distinguish and separate from the complex spectra the absorption characteristic of the NHN- bridge and to compare it with the absorption of intramolecular aliphatic NHN+ hydrogen bridges and the NHN- bridge in the solid state.
2. Experimental DMAN purchased from Aldrich was used after double recrystallization from ethanol. TSATNN and TFAN were synthesized following the procedures given in [ 151 and [ 161. Spectroscopic-grade acetonitrile and acetonitrileds were dried over 3 A molecular sieves. The 1 : 1 complexes of DMAN with TSATNN or TFAN were obtained by dissolving eqttimolar amounts of the corresponding acid in a 0.1 mol dmm3 acetonitrile solution of DMAN. The space group and approximate unit-cell dimensions were determined from rotation and Weissenberg photographs. The diffraction data
74
B. Brzezihki
ei al.iJ. Mol. Struct. 327 (1994) 71-79
M23)
IBM PC/AT computers. Neutral atomic scattering factors for all atoms were taken from [19]. The scattering factors for non-hydrogen atoms were corrected for real and imaginary components. The positions of all hydrogen atoms were determined from difference Fourier synthesis and refined isotropically. IR spectra were recorded in acetonitrile on an FT-IR Bruker IFA 113 v spectrophotometer. A cell with silicon windows and a wedge-shaped layer was used to avoid interference (mean layer thickness, 0.26mm). IR spectra of the solid adduct were recorded on a Perkin-Elmer 180 spectrophotometer. ‘H NMR spectra were recorded in acetonitriled3 at room temperature using a Varian Gemino VT 300 spectrometer at 300MHz using tetramethylsilane as the internal standard.
3. Results and discussion 3.1. The crystal and molecular structure of DMAN- TFAN
c(24) ‘cs9
Fig. 1. Molecular structure and atom numbering of cationic and anionic groups of the DMAN . TFAN adduct.
were collected by MoK, radiation using a KUMA four-circle K-axis computer-controlled KM4 diffractometer. Details of the diffraction experiments, the crystal data collection and refinement are given in Table 1. The intensities were corrected for Lorentz and polarization effects, but not for extinction or absorption. The structure was solved by direct methods using the program SHELXS 86 [17], and refined by the fullmatrix least-squares technique using the Syntex XTL/XTLE structure determination system [ 181 locally adapted by Kowalski for calculation on
The atomic positions (fractional coordinates) in the DMAN - TFAN crystal are collected in Table 2. The atom numbering in protonated DMAN and deprotonated TFAN is shown in Fig. 1, while the important bond lengths and angles are listed in Table 3. In the crystalline lattice the cations and anions are almost oriented perpendicularly (90.1”) with respect to each other. The structure of the cation is close to that reported already in many papers [14, 20-251. In this instance it is almost symmetric although the bridge H-atom is located closer to the N(12) nitrogen atom (&(ii)_H = 1.42(3), &(tZ)-H = 1.22(3), RN(I1)-N(lz) = 2.588(4) A and (NllHN12 = 156(3”)). As a consequence, there are some differences in the bond lengths of the two moieties of the naphthalene skeleton (the maximum deviation from planarity is 0.010 A). The NHN- hydrogen bridges in the anions are asymmetric. The distances of the H-atom from the nitrogen atoms are 0.99(4) and 1.79(3)A. The bridge is significantly bent, (NHN being 138(3)“. The asymmetry of the bridge is only slightly
B. Brzeziriski et al./J. Mol. Struet. 327 (1994)
Table 3 (continued)
Table 3 Interatomic distances and angles
Distance (A) Distance (A) F(21)-C(212) F(22)-C(212) F(23)-C(212) F(24)-C(214) F(25)-C(214) F(26)-C(214) 0(21)-C(211) 0(22)-C(213) N(11). . . N(12) N(l I)-C(11) N(l I)-C(11 1) N(ll)-C(112) N(11). H(1) N(12)-C(18) N(12)-C(113) N(12)-C(114) N(12)-H(1) N(21). .N(22) N(21)-C(21) N(21)-C(211) N(21). H(2) N(22)-C(28) N(22)-C(213) N(22)-H(2) C(ll)-C(12) C(ll)-C(19) C(12)-C(13) C(13)-C(14) C(14)-C(110) C(llO-C(15) C(1 lO)-C(19) C(15)-C(16) C(16)-C(17) C(17)-C(18) C(18)-C(19) C(21)-C(22) C(21)-C(29) C(22)-C(23) C(23)-C(24) C(24)-C(210) C(210)-C(25) C(210)-C(29) C(25)-C(26) C(26)-C(27) C(27)-C(28) C(28)-C(29) C(211)-C(212) C(213)-C(214)
75
71-79
Angles (deg.)
Angles (deg.) 1.308(5) 1.337(6) 1.295(5) 1.268(7) 1.317(5) 1.267(5) 1.237(4) 1.204(6) 2.588(4) 1.468(4) 1.486(5) 1.481(5) 1.42(3) 1.469(4) 1.486(6) 1.492(4) 1.22(3) 2.608(4) 1.416(5) 1.312(5) 1.79(3) 1.423(5) 1.336(4) 0.99(4) 1.366(5) 1.422(4) l&4(5) 1.351(5) 1.410(6) 1.415(5) 1.433(5) 1.352(6) 1.403(5) 1.368(4) 1.423(5) 1.381(5) 1.437(6) 1.377(6) 1.370(7) 1.401(5) 1.419(7) 1.427(5) 1.344(6) 1.394(6) 1.382(6) 1.432(5) 1.508(6) 1.490(7)
C(1 I)-N(l I)-C(l 11) C(ll)-N(l I)-C(112) C(l I)-N(ll)-H(1) C(18)-N(12)-C(113) C(18)-N(12)-C(114) C(18)-N(12)-H(1) C(21)-N(21)-C(211) C(21)-N(21)-H(2) C(21 l)-N(21)-H(2) C(28)-N(22)-C(213) C(28)-N(22)-H(2) C(213)-N(22)-H(2) N(l I)-C(1 l)-C(12) N(ll)-C(ll)-C(19) C(12)-C(1 l)-C(19) C(ll)-C(12)-C(13) C(12)-C(13)-C(14) c(13)-c(14)-c(110) c(14)-c(11o)-c(15) c(14)-c(11o)-c(19) c(15)-c(11o)-c(19) C(llO)-C(15)-C(16) C(15)-C(16)-C(17) C(16)-C(17)-C(18) N(12)-C(18)-C(17) N(12)-C(18)-C(19) C(17)-C(18)-C(19) c(11)-c(19)-c(110) C(ll)-C(19)-C(18) C(llO)-C(19)-C(18) N(21)-C(21)-C(22) N(21)-C(21)-C(29) C(22)-C(21)-C(29) C(21)-C(22)-C(23) C(22)-C(23)-C(24) C(23)-C(24)-C(210) C(24)-C(210)-C(25) C(24)-C(210)-C(29) C(25)-C(210)-C(29) C(210-C(25)-C(26) C(25)-C(26)-C(27) C(26)-C(27)-C(28) N(22)-C(28)-C(27) N(22)-C(28)-C(29) C(27)-C(28)-C(29) C(21)-C(29)-C(210) C(21)-C(29)-C(28) C(210)-C(29)-C(28) 0(21)-C(21 l)-N(21) 0(21)-C(21 l)-C(212) N(21)-C(211)-C(212) 0(22)-C(213)-N(22)
113.0(3) 112.2(3) 100(l) 113.4(3) 111.5(3) lOl(2) 119.0(3) 102(l) 124(l) 126.4(3) 116(2) 117(2) 120.5(3) 118.1(3) 121.3(3) 120.1(4) 120.4(4) 121.7(4) 121.6(4) 118.7(3) 119.6(3) 121.3(4) 120.1(4) 120.3(4) 119.6(3) 118.5(3) 121.9(3) 117.8(3) 125.6(3) 116.7(3) 121.4(3) 119.3(3) 119.1(3) 122.0(4) 120.7(4) 120.0(4) 119.8(4) 120.4(4) 119.8(4) 120.9(4) 121.3(4) 119.8(4) 121.0(3) 117.6(3) 121.4(3) 117.8(3) 125.4(3) 116.8(3) 131.3(4) 115.4(4) 113.2(3) 129.1(4)
0(22)-C(213)-C(214) N(22)-C(213)-C(214) N(ll)-H(l)-N(12) N(21)-H(2)-H(22)
117.4(4) 113.5(4) 156(3) 138(3)
reflected in the geometry of the adjacent groups. Thus the C&- N bond lengths are almost identical. More pronounced differences appear in the trifluoroacetyl groups: rcN = 1.312(5) and 1.336(4), and rco = 1.237(4) and 1.204(6) A. There is a marked difference in the orientation of the trifluoroacetyl groups with respect to the naphthalene plane. The amide groups are planar but not co-planar with the naphthalene skeleton. The normals to the amide and naphthalene planes form the angles 135.1 and 11.1‘, respectively. The NHN hydrogen-bond length in deprotonated TFAN (2.608(4)& is almost the same as in deprotonated TSATNN [14] although the electronic state of the bridge atoms is substantially different. For TFAN the C&-N bond lengths (1.416(5), 1.423(5) A) indicate a hybrydization intermediate between sp2 and sp3 but closer to sp3. For TSATNN, however, these bonds are markedly shorter and differentiated (1.397(7) and 1.336(6)A). The electronic state of the nitrogen atoms N(4) becomes closer to sp2. Simultaneously strong asymmetric location of the H-atom is evidenced. This is why the NHN- bridge in deprotonated TFAN is stronger than in deprotonated TSATNN in spite of the fact that the bridges are of the same length. It should be remembered that in the protonated proton sponge DMAN the hybridization state of the nitrogen atoms is close to sp3 and the hydrogen bonds therein are stronger. 3.2. ‘H NMR spectra in acetonitrile The ‘H NMR data corresponding to the cation and anion are collected in Table 4. The chemical shift of the bridge proton in protonated DMAN is identical with that previously reported [2]. The chemical shifts of the other protons and splittings of the CH3 signals caused by the couplings with the bridge protons are also similar [2,3].
18.63 18.61
+ HNOja + TFAN
+ TSATNN
DMAN DMAN
DMAN
(J = 9.0).
18.66
_ 18.92
a Ref. [2] b Ref. [3]. ’ d = doublet
with HN09,
7.87
7.80
6.93 7.94
H-2,7
7.68
7.62
7.25 7.70
H-3,6
8.01
7.98
7.32 8.04
H-4,5
3.04, 3.03 3.09, 3.08
2.75 3.14
CHS
7.6
7.7
7.2 7.8
J(2,3)
8.1
8.3
7.8 8.4
J(3,4)
1.0
0.9
1.8 0.9
J(2,4)
15.16
16.42
_ -
NHN-
and its complexes
NHN+
(Hz) of DMAN Anion
constants
Cation
shifts @pm) and coupling
DMANa DMAN + HN03b
Compound
Table 4 ‘H NMR chemical
-
7.32
_ _
H-2,7
TFAN
8.74
7.45
_
H-3,6
-
8.46
_
H-4,5
and TSATNN
2.37, 2.32
-
-
CH3
7.74d, 7.62dc
-
-
Ph rings
-
7.7
-
J(2,3)
-
8.3
-
J(3,4)
-
0.9
-
J(2,4)
B. Brzezitiski et al./J. Mol. Struct. 327 (1994)
71-79
WAVENUMBER [l/CM] Fig. 2. IR spectra of (- - -) DMAN and (-)
There is no exchange of protons between the cation and anion, at least on the NMR time scale. The signals from the NHN- bridge protons correspond to lower chemical shift values than the cation. Comparing the those of DMAN - TFAN and DMAN . TSATNN systems, one can conclude that the hydrogen bonding in deprotonated TFAN is stronger than that in deprotonated TSATNN in accordance with IR spectra, which will be discussed later. In the TSATNN anion two closely located CHs signals are observed. The origin of the splitting is not clear. In the crystalline lattice of DMANeTSATNN the two tolyl groups occupy different positions [14]. One can suppose that the situation in solution is similar. However, exchange between two positions followed by the jumping of
its 1 : 1 complexes with: TSATNN (a); TFAN (b).
the bridge proton is probably too fast on the NMR time scale. The two moieties of the naphthalene ring are identical (one signal from protons in positions 3,6). 3.3. IR spectra In the IR spectra of the DMAN complexes both with TFAN and TSATNN absorption “continua” are visible, which extend from about 3200 cm-’ up to at least 4OOcm-’ (Fig. 2). Complete protonization of DMAN takes place which is reflected in the vanishing of Bohlmann bands of the methyl groups attached to the nitrogen atoms. As has been shown previously [1,4-71, the DMAN - H+ cations in acetonitrile absorb over a broad frequency range so that it seemed necessary to
B. Brzezihki et al./J. Mol. Struct. 327 (1994) 71-79
I
. %ooo
3000
3500
,
2500
~~ 1500
2000
WAVENUMBER
1000
500
[l/CM]
Fig. 3. IR difference spectra of 1 : 1 complexes of DMAN with TSATNN (a) and TFAN (b). The DMAN tetrachloroaurate absorption is used as a reference.
,tNti~I+
I
3000
I
2500
I
2000 g/cm-’
”
I
I
600
400
Fig. 4. IR spectra of the solid DMAN - TFAN adduct in Nujol and fluoroluble oil at room (. .) and liquid-nitrogen temperature (-).
B. Brzezihki
et al/J. Mol. Struct. 327 (1994)
separate the absorption of this cation by means of difference spectra. The absorption of DMAN chloroaurate was used as a reference absorption. The difference spectra are shown in Fig. 3. It can be seen that the anionic NHN- bridges give rise to broad but localized V, protonic bands at about 28OOcrK’ (TSATNN) and 275Ocm-’ (TFAN). Both the position and width of the bands indicate that the NHN- bridge in deprotonated TFAN is somewhat stronger than that in deprotonated TSATNN in accordance with the NMR spectra. In the solid-state DMAN-TFAN system the bands ascribed to the NHN+ and NHN- bridges are well separated as shown in Fig. 4. The same is true for the DMAN-TSATNN ion pair [14]. As expected, the v,(NHN-) bands in the solid state are shifted to slightly lower frequencies. The corresponding maxima are located at 272Ocm-’ (TSATNN) and 2640 cm-’ (TFAN). References [l] B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Faraday Trans., 86 (1990) 1777. [2] B. Brycki, B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, Magn. Reson. Chem., 29 (1991) 558. [3] Z. Dega-Szafran, B. Nowak-Wydra and M. Szafran, Magn. Reson. Chem., 31 (1993) 726. [4] B. Brzezinski, T. Glowiak, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 1643; Croat. Chem. Acta, 65 (1992) 101. [5] B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 857. [6] B. Brzezinski, G. Schroeder, E. Grech, Z. Malarski and L. Sobczyk, J. Mol. Struct., 274 (1992) 75.
71-79
79
[7l B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, J. Chem. Sot., Perkin Trans. 2, (1991) 1267. [8] B. Brzezinski, A. Jarczewski, J. Olejnik and G. Schroeder, J. Chem. Sot., Perkin Trans. 2, (1992) 2257. [9] G. Schroeder, B. Brzezinski and A. Jarczewski, J. Mol. Struct., 274 (1992) 83. WI B. Brzezinski, E. Grech, Z. Malarski and L. Sobczyk, Pol. J. Chem., 68 (1994) 261. Pll E. Grech, Z. Malarski and L. Sobczyk, Pol. J. Chem., 52 (1978) 131. WI D. Schioberg and G. Zundel, J. Chem. Sot., Faraday Trans 2, 69 (1973) 771. [I31 B. Brzezinski and G. Zundel, J. Chem. Sot., Faraday Trans. 2, 79 (1983) 1249. 1141Z. Malarski, T. Lis, E. Grech, J. Nowicka-Scheibe and K. Majewska, J. Mol. Struct., 221 (1990) 227. 1151F. Hibbert and M.A. Malana, J. Chem. Sot., Perkin Trans. 2, (1992) 755. Ml H.H. Hodgson and J.S. Whitehurst, J. Chem. Sot., (1947) 80. 1171G.M. Sheldrick, SHELXS 86,Program for Crystal Structure Solution, University of Gottingen, Germany, 1986. WI Syntex XTL/XTLE Structure Determination System, Syntex Analytical Instruments, Cupertino, CA, 1976. 1191International Tables for X-ray Crystallography, Vol. IV, Kynoch Press, Birmingham, 1974. PO1 D. Pyialska, R. Pyialski and T. Borowiak, J. Crystallogr. Spectrosc. Res., 13 (1983) 211. PI T. Giowiack, Z. Malarski, L. Sobczyk and E. Grech, J. Mol. Struct., 157 (1987) 329. PI K. Wozniak, T.M. Krygowski, B. Kariuki, W. Jones and E. Grech, J. Mol. Struct., 240 (1990) 111. 1231J.A. Kanters, A. Schouten, A.J.M. Duisenberg, T. Glowiak, Z. Malarski, L. Sobczyk and E. Grech, Acta Crystallogr., Sect. C, 47 (1991) 2148. 1241J.A. Kanters, A. Schouten, J. Kroon and E. Grech, Acta Crystallogr., Sect. C, 47 (1991) 807. ~251T. GIowiak, E. Grech, Z. Malarski and L. Sobczyk, J. Mol. Struct., 295 (1993) 105.