Chemistry of diaminomaleonitrile: Synthesis and structure of two unexpected products from its condensation with 2,5-hexanedione

Article abstract of DOI:10.1023/A:1009557123632

For the synthesis of precursors to cellulose-based ion exchange materials, the condensation of diaminomaleonitrile with 2,4-pentanedione and 2,5-hexanedione was explored. Whilst the former diketone yielded the expected 1,4-diazepine (2), the latter gave either a pyrrole derivative (3) or an unusual triazabicyclononene (4), depending on the conditions used. Compound 2 crystallizes in the monoclinic space group P2₁/c with a = 8.9313(10) A, b = 9.0370(7) A, c = 11.4448(9) A, β= 102.48(8)°, V = 901.89(14) A³, and Z = 4. Compound 3 crystallizes in the orthorhombic space group Pna2₁ with a = 12.0342(8) A, b = 8.3760(8) A, c = 10.7026(11) A, V = 1078.81(17) A³, and Z = 4. Compound 4 crystallizes in the monoclinic space group P2₁/c with a = 9.0157(5) A, b = 13.5374(9) A, c = 12.8751(16) A, β= 99.506(5)°, V = 1549.82(15) A³, and Z = 4. In both 3 and 4 the aminovinyl substituent shows evidence for involvement of the lone pair on nitrogen with the carbon π-system. Also, 3 and 4 are highly associated in the solid state via hydrogen bonding.

Full text of DOI:10.1023/A:1009557123632

Journal of Chemical Crystallography, Vol. 30, No. 5, 2000
Chemistry of diaminomaleonitrile: synthesis and structure
of two unexpected products from its condensation
with 2,5-hexanedione
(1)
(2)
Joel T. Mague * and Etim E. Eduok *
Received May 6, 2000
For the synthesis of precursors to cellulose-based ion exchange materials, the condensation
of diaminomaleonitrile with 2,4-pentanedione and 2,5-hexanedione was explored. Whilst
the former diketone yielded the expected 1,4-diazepine (2), the latter gave either a pyr-
role derivative (3) or an unusual triazabicyclononene (4), depending on the conditions
˚
used. Compound 2 crystallizes in the monoclinic space group P2
1
/c with a = 8.9313(10) A,
˚
˚
�
˚
3
b = 9.0370(7) A, c = 11.4448(9) A, � = 102.48(8) , V = 901.89(14) A , and Z = 4. Compound
˚
˚
3
crystallizes in the orthorhombic space group Pna2
1
with a = 12.0342(8) A, b = 8.3760(8) A,
˚
˚
3
c = 10.7026(11) A, V = 1078.81(17) A , and Z = 4. Compound 4 crystallizes in the monoclinic
˚
˚
˚
�
space group P2
1
/c with a = 9.0157(5) A, b = 13.5374(9) A, c = 12.8751(16) A, � = 99.506(5) ,
˚
3
V = 1549.82(15) A , and Z = 4. In both 3 and 4 the aminovinyl substituent shows evidence
for involvement of the lone pair on nitrogen with the carbon �-system. Also, 3 and 4 are highly
associated in the solid state via hydrogen bonding.
KEY WORDS: Diketone; diaminomaleonitrile; diazepine; pyrrole; triazabicyclononene.
Introduction
pared in the form of long belts, which are very useful
in countercurrent ion exchange operations. To pro-
2
Ion exchange materials are particularly valuable
vide some degree of size-selectivity as well as the po-
tential for strong cation binding, a cyclic chelating site
attached to cellulose was envisaged (1).
in hazardous waste treatment because of their abil-
ity to preferentially absorb toxic metal ions. A sig-
nificant challenge in the design and preparation of
such materials for large-scale applications is the gen-
eration of appropriate supports for the ion exchange
sites. A particularly attractive support is cellulose
since, depending on the type used, one can have the
resulting ion exchangers in the form of long fibers,
sheets of controlled porosity or porous monoliths.
Indeed, there is significant industrial interest in ion
exchange papers and fibers produced by the phos-
1
phorylation or sulfonation of paper and cotton. For
example, phosphorylated cotton can readily be pre-
(
(
1)
2)
Department of Chemistry, Tulane University, New Orleans,
Louisiana 70118.
Department of Chemistry, Xavier University of Louisiana, New
Orleans, Louisiana 70125.
Consideration of possible routes to 1 led to the de-
cision to employ the synthetic pathway outlined in
Scheme 1 in which the first step involves Schiff-base
chemistry. Whilst the reaction of diaminomaleonitrile
*
To whom correspondence should be addressed.
3
11
1
074-1542/00/0500-0311$18.00/0 �C 2000 Plenum Publishing Corporation

312
Mague and Eduok
Scheme 1
with2,4-pentanedioneproceededtogivetheexpected
2,3-Dicyano-5,7-dimethyl[1,4]diazepine (2)
3� 6
intermediate condensation product A (n = 1 (2))
,
in the case of other diketones these initial reac-
tions took different courses. We report here on these
results.
To a solution of 24.00 g (0.218 mol) of 98% di-
aminomaleonitrile in 200.0 mL of 50% glacial acetic
acid contained in a dry 250-mL round-bottom flask
was added 28.96 g (0.289 mol) of 2,4-pentanedione in
one portion and the mixture was stirred at room tem-
perature. Over a 5-min period, the solution turned
dark and stirring was continued overnight. The initial
brown solid that resulted was filtered off, washed with
cold distilled water and dried in vacuo to give a white
Experimental
All solvents were purified by standard methods.
Proton and 13C NMR spectra were obtained on a
IBM/Bruker AF200 instrument at 200.133 and 50.324
MHz, respectively. Chemical shifts are referred to
tetramethylsilane (� = 0.0) as an external standard.
�
crystalline material (32.00 g, 85%), mp 198–200 C
(dec). Anal. Calcd for C H N : C, 62.78%; H, 4.69%;
9
8
4
1
N, 32.53%. Found: C, 62.7%; H, 4.6%; N, 32.1%. H

Chemistry of diaminomaleonitrile
313
Table 1. Crystal Data and Summary of Intensity Data Collection and Refinement
Compound
2
3
4
CCDC deposit no.
Color/shape
CCDC-1003/5873
Colorless block
C9H8N4
172.19
293
CCDC-1003/5874
Amber block
C10H10N4
186.22
293
Orthorhombic
Pna21
a = 12.0342(8)
b = 8.3760(8)
c = 10.7026(11)
CCDC-1003/5875
Colorless plate
C14H14N8
294.33
293
Monoclinic
P21/c
a = 9.0157(5)
b = 13.5374(9)
c = 12.8751(6)
� = 99.506(5)
1549.82(15)
4
Empirical formula
Formula weight
Temperature, K
Crystal system
Space group
Monoclinic
P21/c
˚
Unit cell dimensions A, deg
a = 8.9313(10)
b = 9.0370(7)
c = 11.4448(9)
�
= 102.485(8)
Volume A3
˚
901.89(14)
4
1078.81(17)
4
1.147
0.074
Z
Density (calculated), mg/m3
1.268
0.083
1.261
0.084
�
1
Absorption coefficient, mm
Diffractometer/scan
Radiation/wavelength
Enraf-Nonius CAD-4/ω/2�
˚
Mo K�� = 0.71073 A
�
range for data collection
2.34 – 25.05
1709
2.96 – 25.07
1015
2.20 � 25.07
2931
2746 (Rint = 0.032)/
1584 [I > 2�(I)]
2746/0/217
Reflections measured
Indep./obs. reflections
1602 (Rint = 0.021)/
1015/846 [I> 2�(I)]
1
287 [I > 2�(I)]
Data/restraints/parameters
Extinction coefficient
1602/0/121
0.056(6)
1.502
1015/1/145
Goodness of fit on F2
1.046
1.000
Final R indices [I > 2�(I)]
R1 = 0.0357
wR2 = 0.1021
R1 = 0.054
wR2 = 0.1109
R1 = 0.0301
wR2 = 0.0857
R1 = 0.0462
wR2 = 0.0929
R1 = 0.037
wR2 = 0.0888
R1 = 0.1163
wR2 = 0.1082
R indices (all data)
1
NMR (CDCl3, 288 K): � 4.30 (d, J = 10.3 Hz, 1H,
CHaHb), 2.33 (s, 6H, CH3), 1.86 (d, J = 10.3 Hz, 1H,
N, 30.08%. Found: C, 64.2%; H, 5.3%; N, 29.8%. H
NMR (d acetone): � 6.99 (br, 2H, NH ), 5.82 (s, 2H,
== CH), 2.13 (s, 6H, CH ). C NMR (d acetone): �
6
2
13
13
CHaHb). C NMR (d6 acetone): � 157.9 (C == C), 123.9
3 6
(
C == N---- ), 115.7 (C� N), 49.9 (CH2), 26.5 (CH3).
132.1, 129.0, 116.5, 113.4, 108.9, 91.4, 11.8 (CH ).
3
N-(2-Amino-1,2-dicyanoethenyl)-2,
9-(2-Amino-1,2-dicyanoethenyl)-3,4-dicyano-
5-dimethylpyrrole (3)
1,6-dimethyl-2,5,9-triazabicyclo[1.2.4]non-3-ene (4)
To a solution of 2.752 g (0.0295 mol) of 98%
diaminomaleonitrile in 100.0 mL of 50% glacial
acetic acid was added 2.905 g (0.0295 mol) of
To a solution of 5.502 g (0.0509 mol) of 98% di-
aminomaleonitrile in 90.0 mL of dry dichloromethane
in a 250 mL round-bottom flask was added 5.81 g
(0.0509 mol) of 2,5-hexanedione and 5.0 mL of 50%
2
,5-hexanedione and the solution was stirred
�
overnight at ambient temperature. The brown solid
that formed was filtered off, dried in vacuo and re-
crystallized from acetone/diethyl ether as amber col-
glacial acetic acid. The mixture was heated at 40 C
overnight to afford a light brown solid which was fil-
tered off, dried in vacuo and recrystallized from ace-
tone to give off-white crystals of the product (74%),
�
ored crystals (76%), mp 138 C. Compound 3 can also
�
be recovered from the initial filtrate obtained in the
synthesis of 4 by evaporation of the filtrate to dry-
ness. Anal. Calcd for C10H10N4: C, 64.50%; H, 5.42%;
mp 165–167 C. Anal. Calcd for C14H14N8: C, 57.14%;
H, 4.91%; N, 38.06%. Found: C, 57.2%; H, 4.8%; N,
1
38.0%. H NMR (d6 acetone): � 6.71 (br, 2H, NH2),

314
Mague and Eduok
Scheme 2
5
.91 (br, 2H, NH), 2.23 (m, 2H, CHaHb), 1.69 (m, 2H,
Lorentz and polarization effects and as the intensity
monitors showed only statistical fluctuations, no
decay corrections were needed. The structures were
solved by direct methods which provided positions for
the majority of the non-hydrogen atoms in the initial
E-maps. Successive cycles of full-matrix, least-squares
refinement and calculation of difference maps served
to locate the remainder of the non-hydrogen atoms,
following whose refinement a difference map indi-
cated the position for the majority of the hydrogen
atoms. Those attached to carbon were included as
riding contributions in calculated positions, with
isotropic displacement parameters 10% larger than
those of the corresponding carbon atoms, while those
attached to nitrogen were refined with isotropic dis-
placement parameters. All final difference maps were
essentially featureless. Initial processing of the raw
13
CHa Hb), 1.55 (s, 6H, CH3). C NMR (d6 acetone): �
1
2
34.6, 117.2, 116.6, 114.1, 108.5, 93.1, 80.5, 36.2 (CH2),
5.4 (CH3).
X-ray crystallography
Crystals of 2–4, obtained as described above,
were cut to size as necessary and mounted on thin
glass fibers with epoxy cement. General procedures
for crystal alignment, unit cell determination and
refinement and collection of intensity data have been
7
published. Details specific to the present work are
collected in Table 1. In all instances, the initial cells
indicated by the CAD-4 software were confirmed
by the observation of the appropriate diffraction
symmetry and the space groups were uniquely de-
termined by the systematic absences observed in the
final data sets. Raw intensity data were corrected for
8
intensity data was performed with XCAD4, while
all other crystallographic calculations employed the
9
SHELXTL-PLUS system.

Chemistry of diaminomaleonitrile
315
Scheme 3
Results and discussion
diaminomaleonitrile with 2,5-hexanedione was at-
tempted using the same conditions. However, the H
1
The condensation of diaminomaleonitrile with
,4-pentanedione occurs readily in 50% glacial acetic
and 13C NMR spectra of the crystalline product (3)
did not correspond to those expected for the desired
product (A; n = 2), so the crystal structure was deter-
mined to establish the identity of 3. This showed the
compound to be an N-vinylpyrrole derivative (See
Scheme 2), with which formulation the NMR spectra
are fully consistent. Scheme 2 presents a plausible
mechanism for the formation of 3, which is based on
that for the reaction of a 1,4-diketone with ammonia,
a reaction that is known to give the corresponding
2,5-disubstituted pyrrole.10
2
acid under ambient conditions to afford the expected
1
13
diazepine, 2, in high yield. The H and C NMR spec-
tra serve to adequately characterize the compound
and it should be noted that at room temperature the
resonances attributed to the methylene protons ap-
pear as featureless, broad peaks nearly indistinguish-
able from the baseline. This clearly indicates that
a “ring-flip” is occurring at a moderate rate at this
temperature.
In extending the above methodology to the for-
mation of larger ring systems, the condensation of
In a further attempt to prepare the intermedi-
ate A (n = 2), the reaction of diaminomaleonitrile

316
Mague and Eduok
4
Table 2. Atomic Coordinates (� 10 ) and Equivalent Isotropic
Table 3. Selected Bond Lengths [ A˚ ] and Angles [Deg] for 2
˚
2
3
Displacement Parameters (A � 10 ) for 2. Ueq is Defined as One-
Third of the Trace of the Orthogonalized Uij Tensor
C(2) ---- N(1)
C(2) ---- C(3)
1.284(2) N(2) ---- C(6)
1.497(2) C(6) ---- C(8)
1.380(2)
1.372(2)
1.374(2)
x
y
z
Ueq
----
----
C(3) C(4)
C(4) ---- N(2)
1.504(2) C(8) N(1)
1.285(2)
N(1)
N(2)
N(3)
N(4)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
6608(2)
5460(1)
1711(2)
3190(2)
9242(2)
7580(2)
7078(2)
6684(2)
7744(2)
4569(2)
2973(2)
5100(2)
4027(2)
2769(2)
349(1)
586(2)
10138(1)
8380(1)
8531(2)
10755(2)
9995(2)
9461(2)
8145(1)
8085(1)
7706(2)
8889(1)
8691(2)
9695(1)
10296(1)
47(1)
42(1)
80(1)
68(1)
70(1)
47(1)
46(1)
41(1)
54(1)
41(1)
52(1)
41(1)
49(1)
C(3) C(2) N(1)
----
----
121.30(14) C(4) N(2) C(6) 120.40(13)
----
----
C(2) C(3) C(4)
---- ----
----
----
102.92(12) C(8) C(6) N(2) 125.99(13)
---- ----
N(2) C(4) C(3)
---- ----
121.05(14) C(6) C(8) N(1) 126.45(14)
120.31(13)
----
----
3713(2)
2883(2)
2717(2)
2441(2)
821(2)
� 251(2)
1294(2)
894(2)
C(2) N(1) C(8)
NMR spectra are fully consistent with this structure
and the proposed mechanism for the formation of 4
is presented in Scheme 3. Although the reasons for
the different course of this reaction under the second
set of conditions are not entirely clear, we do note
that here there is a higher concentration of reactants,
which would favor attack of a second molecule of the
diaminomaleonitrile as suggested in the fourth step.
It seems clear from these results that 2,5-hexanedione
shows a distinct preference for reacting with diamino-
maleonitrile in the same way it reacts with ammonia
and primary amines. That is, only one of the amino
groups reacts with both carbonyl groups rather hav-
ing each amino group react independently with one
carbonyl group as was desired.
2399(2)
3119(2)
and 2,5-hexanedione was attempted under less polar
and less acidic conditions. Once again, instead of the
desired condensation product a new and unexpected
species (4) was formed as the major product together
with lesser amounts of 3. The correct formulation of 4
was provided by determination of the crystal structure
(
See Scheme 3), which showed it to be the product of
the condensation of the diketone with two equivalents
of the diaminomaleonitrile. The observed H and
In the solid, 2 (Fig. 1) exhibits no unusually
short intermolecular contacts. The short N(1)---- C(2)
and N(2)---- C(4) distances clearly indicate these are
1
13
C
double bonds, while the near equivalence of the
4
Table 4. Atomic Coordinates (� 10 ) and Equivalent Isotropic
˚
2
3
Displacement Parameters (A � 10 ) for 3. Ueq is Defined as One-
Third of the Trace of the Orthogonalized Uij Tensor
x
y
z
Ueq
N(1)
N(2)
N(3)
N(4)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
� 3(2)
� 2411(2)
� 3618(2)
� 997(2)
514(4)
960(2)
� 907(4)
1244(3)
2620(3)
� 1674(5)
� 252(3)
189(4)
1663(4)
2135(3)
3610(3)
838(3)
8935(2)
9933(3)
7033(2)
6834(2)
8004(5)
8765(3)
9395(3)
9970(3)
9686(2)
9987(4)
8582(2)
9324(3)
7580(2)
7283(2)
50(1)
88(1)
70(1)
68(1)
120(2)
66(1)
70(1)
64(1)
54(1)
77(1)
48(1)
60(1)
47(1)
53(1)
776(2)
1697(2)
1495(2)
449(2)
� 169(3)
� 1137(2)
� 1846(2)
� 1550(2)
� 2713(2)
� 131(3)
1631(3)
1427(3)
Fig. 1. Perspective view of 2. Thermal ellipsoids are drawn at
the 25% probability level and hydrogen atoms are represented by
spheres of arbitrary radius.

Chemistry of diaminomaleonitrile
317
˚
Table 5. Selected Bond Lengths [A] and Angles [Deg] for 3
C(2) ---- C(3)
1.348(4) N(1) ---- C(7)
1.394(3) C(7) ---- C(9)
1.401(5) C(7) ---- C(8)
1.354(4) C(9) ---- N(4)
1.382(3) C(9) ---- C(10)
1.420(3)
C(2) ---- N(1)
C(3) ---- C(4)
C(4) ---- C(5)
C(5) ---- N(1)
1.356(3)
1.420(4)
1.329(3)
1.446(3)
C(3) ---- C(2) ---- N(1) 106.7(3)
C(5) ---- C(4) ---- C(3)
108.6(3)
C(4) ---- C(5) ---- N(1) 106.8(2)
C(5) ---- N(1) ---- C(2) 109.3(2)
C(5) ---- N(1) ---- C(7) 125.7(2)
C(2) ---- N(1) ---- C(7) 124.0(2)
C(2) ---- C(3) ---- C(4
108.6(3)
N(1) ---- C(7) ---- C(8) 118.0(2)
N(4) ---- C(9) ---- C(7) 126.7(2)
N(4) ---- C(9) ---- C(10) 115.2(2)
C(7) ---- C(9) ---- C(10) 118.1(2)
C(9) ---- C(7) ---- C(8) 120.1(2)
Fig. 2. Perspective view of 3. Thermal ellipsoids are drawn at
the 25% probability level and hydrogen atoms are represented by
spheres of arbitrary radius.
N(2)---- C(6), C(6)---- C(8), and C(8)---- N(1) distances
suggests a significant amount of �-delocalization, pre-
sumably with participation of the lone pairs on nitro-
gen, over this portion of the ring. It should be noted,
however, that the dihedral angle between the planes
defined by N(2), C(6), C(8), N(1) and by N(1), C(2),
while, conversely, each of the nitrile substituents is as-
sociated with the amino group of a different neighbor-
ing molecule (See Fig. 2). The pyrrole moiety is planar
within experimental error with C(7) 0.207(4) A˚ out
�
C(4), N(2) is 32.90(8) , while the methylene carbon
�
(
C(3)) is bent 58.0(1) away from the latter plane.
of the mean plane of the ring indicating a significant
pyramidality in the geometry about N(1). The best
plane through the vinyl substituent (C(7)---- C(10),
Compound 3 is associated in the solid state via
H-bonding between the amino group and nitrile sub-
stituents on two neighboring molecules (Table 8),
�
N(1), N(4)) is inclined at 79.14(8) to the plane of
the pyrrole ring, suggesting there can be no significant
4
Table 6. Atomic Coordinates (� 10 ) and Equivalent Isotropic
�
-interaction with the latter. On the other hand, the
˚
2
3
Displacement Parameters (A � 10 ) for 4. Ueq is Defined as One-
Third of the Trace of the Orthogonalized Uij Tensor
short C(9)---- N(4) distance and the fact that the sum of
�
angles about N(4) is 359 indicates that N(4) is virtu-
ally planar and that there is significant involvement of
x
y
z
Ueq
its lone pair with the �-system of the vinyl substituent.
N(1)
N(2)
N(3)
N(4)
N(5)
N(6)
N(7)
N(8)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
6372(2)
8322(2)
4973(2)
� 757(2)
1620(2)
3932(2)
1682(2)
3552(2)
7388(2)
6219(2)
5043(2)
4995(2)
2513(3)
2443(2)
1682(2)
2424(3)
3798(2)
5226(2)
220(2)
3627(2)
3377(2)
1523(1)
989(2)
� 1120(2)
2357(1)
2381(1)
612(1)
3243(2)
3098(2)
2489(1)
1958(2)
3900(2)
2790(2)
2499(2)
1543(2)
1388(1)
1116(2)
1155(2)
1375(2)
594(2)
1637(2)
� 378(2)
� 1333(2)
� 1939(2)
� 838(2)
1053(1)
� 267(1)
739(1)
49(1)
63(1)
48(1)
58(1)
55(1)
32(1)
40(1)
36(1)
44(1)
36(1)
31(1)
35(1)
53(1)
38(1)
49(1)
48(1)
35(1)
46(1)
39(1)
34(1)
32(1)
37(1)
105(2)
740(2)
403(2)
� 568(2)
589(2)
748(2)
1681(2)
2101(2)
1545(2)
2289(2)
� 1279(2)
� 455(2)
� 35(2)
� 485(2)
1451(2)
2299(2)
1905(2)
Fig. 3. Perspective view of 4. Thermal ellipsoids are drawn at
the 25% probability level and hydrogen atoms are represented by
spheres of arbitrary radius.
� 358(2)

318
Mague and Eduok
this portion of the molecule (although possibly less
than in 2) and it should be noted that the dihedral an-
gle between the best planes defined by N(8), C(13),
�
C(12), N(7) and by N(8), C(9), C(6), N(7) is 24.7(1) .
A
search of the Cambridge Crystallo-
graphic Database did not locate any structures
for 1,4-diazepines to which 2 could be com-
pared but did provide those of 5 (R = p-tol;
Fig. 4. Side view of the 7-membered ring in 2.
0
11
R = NPhMe) and 6 (R = 2-[2-(2,3,6-trimethyl-7-
12
methylenebicyclo[4.4.0]decyl)]-ethyl) which permit
Compound 4 is also associated in the solid state
via H-bonding interactions between the four {N---- H}
moieties on a given molecule and nitrile substituents
on neighboring molecules (Table 8) and, as with 3,
all of its nitrile groups except for that containing
N(5) interact with {N---- H} units on other neighbors.
As 4 incorporates the majority of the structural el-
ements of 2 and 3 there are close similarities in a
number of details between them (See Fig. 3). Thus
the mean plane of the vinyl group is inclined to the
�
best plane defined by C(6)---- C(9) by 87.47(7) , while
the N(1)---- C(2) distance is comparable in length to
that for C(2)---- C(3). This together with the sum of
angles about N(1) being 352 again suggests signifi-
some comparisons to be made with 4. In particular,
the N---- C(2) distance of 1.465(5) A in 5 and the N
˚
0
----
C
�
˚
˚
and N---- C(2) distances (1.493(5) A and 1.460(5) A re-
cant involvement of the lone pair on N(1) with the
spectively) in 6 compare well with the N(8)---- C(9) and
N(7)---- C(6) distances (1.467(3) A and 1.480(3) A re-
˚
˚
�
-system of the vinyl group. The near equivalence
of the N(8)---- C(13), C(13)---- C(12), and C(12)---- N(7)
spectively) in 4. On the other hand, there is a greater
0
distances suggests significant �-delocalization over
difference between the C(1)---- C(1) and the C(1)---- N
˚
Table 7. Selected Bond Lengths [A] and Angles [Deg] for 4
N(1) ---- C(2)
N(6) ---- C(3)
1.348(3)
1.418(2)
N(8) ---- C(9)
C(1) ---- C(2)
1.467(3)
1.450(3)
N(6) ---- C(6)
N(6) ---- C(9)
1.458(2)
1.471(2)
C(2) ---- C(3)
C(3) ---- C(4)
1.355(3)
1.437(3)
N(7) ---- C(12)
N(7) ---- C(6)
1.393(3)
1.480(3)
C(11) ---- C(12)
C(12) ---- C(13)
1.434(3)
1.362(3)
N(8) ---- C(13)
1.377(2)
C(13) ---- C(14)
1.434(3)
C(3) ---- N(6) ---- C(6)
C(3) ---- N(6) ---- C(9)
C(6) ---- N(6) ---- C(9)
C(12) ---- N(7) ---- C(6)
C(13) ---- N(8) ---- C(9)
N(2) ---- C(1) ---- C(2)
N(1) ---- C(2) ---- C(3)
N(1) ---- C(2) ---- C(1)
C(3) ---- C(2) ---- C(1)
C(2) ---- C(3) ---- N(6)
C(2) ---- C(3) ---- C(4)
N(6) ---- C(3) ---- C(4)
N(6) ---- C(6) ---- N(7)
N(6) ---- C(6) ---- C(5)
N(7) ---- C(6) ---- C(5)
119.98(16)
118.85(15)
109.69(15)
123.55(17)
122.31(17)
178.3(3)
N(6) ---- C(6) ---- C(7)
N(7) ---- C(6) ---- C(7)
C(5) ---- C(6) ---- C(7)
N(8) ---- C(9) ---- N(6)
N(8) ---- C(9) ---- C(10)
N(6) ---- C(9) ---- C(10)
N(8) ---- C(9) ---- C(8)
N(6) ---- C(9) ---- C(8)
C(10) ---- C(9) ---- C(8)
C(13) ---- C(12) ---- N(7)
C(13) ---- C(12) ---- C(11)
N(7) ---- C(12) ---- C(11)
C(12) ---- C(13) ---- N(8)
C(12) ---- C(13) ---- C(14)
N(8) ---- C(13) ---- C(14)
101.41(16)
113.25(17)
113.26(18)
110.35(16)
106.66(16)
111.50(16)
112.68(16)
101.99(16)
113.72(18)
129.19(18)
116.56(18)
113.98(17)
127.78(18)
116.86(17)
115.26(17)
124.1(2)
115.48(19)
120.36(19)
118.65(18)
119.46(18)
121.81(17)
111.05(16)
112.13(17)
105.91(18)

Chemistry of diaminomaleonitrile
319
Table 9. Cremer-Pople Parameters for 2, 4, 5, and 6
2
4
5
6
˚
q2 (A)
0.825
0.277
0.166
0.588
0.954
0.263
0.315
0.465
˚
q3 (A)
ϕ2(Deg)
ϕ3(Deg)
Q (A)
154.48
51.11
0.870
338.06
359.97
0.611
64.3
321.4
0.990
358.16
242.13
0.562
˚
Fig. 5. Side view of the 7-membered ring in 4.
conformation for 2 as opposed to the twist-chair of 5
is a result of the larger number of � bonds in the for-
mer as well as the greater amount of �-delocalization
˚
˚
----
----
----
distances (1.354(4) A and 1.408(4) A respectively) in 5
over the N(1) C(8) C(6) N(2) unit. As 2 is flux-
ional in solution, other conformations are evidently
accessible so we suggest that the one observed in the
crystalisthatwhichpermitsthemostefficientpacking.
Based on the proposed mechanism for the formation
of 4, the observed conformation is that expected with
additional rigidity provided by the �-delocalization
over the N(7)---- C(12)---- C(13)---- N(8) unit.
than between the C(12)---- C(13) distance (1.362(3) A)
and the average of the C(12)---- N(7) and C(13)---- N(8)
˚
˚
distances (1.385(3) A) in 4 indicating a greater de-
gree of �-delocalization over this 4-atom portion in
as compared to 5. This can be attributed to the
markedly different conformation of the 7-membered
ring in 5 (vide infra) which diminishes the opportunity
for overlap of the lone pair orbital on nitrogen with
4
the � system on the intervening carbon atoms.
A Cremer-Pople analysis1
3,14
of the conforma-
Acknowledgment
tions of the 7-membered rings in 2, 4, 5, and 6 yields
the parameters presented in Table 9, while Figs. 4 and
The support of the Department of De-
fense/Defense Nuclear Agency Bioenvironmental
Hazards Research Program Tulane/Xavier Univer-
sities (Grant No. 93DNA-2 to EEE) and the De-
partment of Chemistry of Tulane University (JTM)
is gratefully acknowledged. We thank Drs. Harry E.
Ensley and Rogers Harry-O’kuru for valuable discus-
sions.
5
show the conformations adopted by 2 and 4. From
this analysis the conformations of 2, 4, and 6 belong to
the sofa family and most closely correspond, respec-
¯
¯
tively, to the S3, S1, and S3 forms. By contrast, that
in 5 (with crystallographically imposed C2 symme-
try) most closely approximates the TC 3 (twist-chair)
form. We consider that the adoption of a sofa-type
˚
Table 8. Hydrogen Bonds for 3 and 4 [A and Deg]
Compound
D ---- H ���A
d(D ---- H) d(H���A) d(D���A) <(DHA)
a
3
4
N(4) ---- H(4NA)���N(3)
0.86(3)
0.89(4)
2.18(3)
2.23(4)
3.025(3)
1.55(3)
166(3)
155(3)
b
c
N(4) ---- H(4NB)���N(2)
N(1) ---- H(1NA)���N(4)
0.91(3)
0.91(3)
0.85(3)
0.86(2)
2.11(3)
2.27(3)
2.51(3)
2.36(2)
2.960(3)
3.090(3)
3.297(3)
3.220(3)
155(2)
149(2)
155(2)
d
N(1) ---- H(1NB)���N(3)
e
N(7) ---- H(7N)���N(2)
N(8) ---- H(8N)���N(3) f
174.0(19)
Symmetry transformations used to generate equivalent atoms.
a
x + 1/2, � y + 1/2, z.
b
�
x � 1/2, y + 1/2, z � 1/2.
c
d
e
f
x + 1, � y + 1/2, z + 1/2.
x, � y + 1/2, z + 1/2.
x � 1, y, z.
�
x + 1, � y, � z.

320
Mague and Eduok
References
8. Harms, K.; Wocadlo, S. Program to Extract Intensity Data from
Enraf-Nonius CAD-4 Files; University of Marburg; Germany,
1
987.
1
2
3
4
. Helffereich, F. Ion Exchange; Dover: New York, 1995; pp 18–
9.
. Muendel, C.H.; Selke, W.A. Ind. Eng. Chem. 1955, 47,
74.
. Bridson, P.K.; Harry-O’kuru, R.E. Nucleos. Nucleot. 1991, 10,
35.
9. Bruker AXS, SHELXTL-PLUS, Version 5.1; Madison, WI,
1997.
10. Roberts, J.D.; Caserio, M.C. Basic Principles of Organic Chem-
istry, 2nd ed.; W. A. Benjamin: Menlo Park, CA, 1977; p 778.
11. Wenzel, M.; Beckert, R.; Gunther, W.; Gorls, H. Eur. J. Org.
Chem. 1998, 183.
12. Yosief, T.; Rudi, A.; Stein, Z.; Goldberg, I.; Gravalos, G.M.D.;
Schleyer, M.; Kashman, Y. Tetrahed. Lett. 1998, 39, 3323.
13. Cremer, D.; Pople, J.A. J. Am. Chem. Soc. 1975, 97, 1354.
14. Boessenkool, I.K.; Boeyens, J.C.A. J. Cryst. Mol. Struct. 1980,
10, 11.
1
3
3
. Harry-O’kuru, R.E. Ph. D. Dissertation, Memphis State Uni-
versity 1988.
5. Ried, W.; Konigstein, F.-J. Chem. Ber. 1959, 92, 2532.
6. Ried, W.; Pfaender, P. Liebigs Ann. Chem. 1961, 640, 111.
7. Mague, J.T.; Lloyd, C.L. Organometallics 1988, 7, 983.