N-arylmaleimide derivatives

Article abstract of DOI:10.1023/A:1011345925270

Nine phenyl substituted N-phenylmaleimide monomers for photopolymerization studies have been characterized by x-ray crystallography. Structures for N-(2′-t-butylphenyl)maleimide (1), P2₁/n, a = 10.197(3) A, b = 11.904(4) A, c = 10.496(5) A, β =

Full text of DOI:10.1023/A:1011345925270

Journal of Chemical Crystallography, Vol. 30, No. 9, 2000
N-Arylmaleimide derivatives
Christopher W. Miller,(1) Charles E. Hoyle,(1) Edward J. Valente,(2)* Jeffrey D. Zubkowski,(3)
and E. Sonny Jo¨nsson(4)
Received August 31, 2000
Nine phenyl substituted N-phenylmaleimide monomers for photopolymerization studies have
been characterized by x-ray crystallography. Structures for N-(20-t-butylphenyl)maleimide (1),
P21/n, a = 10.197(3) A, b = 11.904(4) A, c = 10.496(5) A, = 100.61(3) ; N-(20-trifluoro-
˚
˚
˚
˚
˚
˚
methylphenyl)maleimide (2), P21/c, a = 11.763(8) A, b = 10.699(9) A, c = 8.284(5) A,
=
90.02(5) ; N-(20,60-diisopropylphenyl)maleimide hemibenzene solvate (3), Pc, a =
16.747(6) A, b = 8.552(3) A, c = 12.899(4) A, = 105.08(3) ; N-(20,60-diisopropylphenyl)
˚
˚
˚
˚
˚
˚
maleimide (unsolvated) (4), C2/c, a = 28.146(10) A, b = 8.434(4) A, c = 12.881(4) A,
=
=
92.20(4) ; N-(20-bromo-30,50-bis(trifluoromethyl)phenyl) maleimide (5), P21/n, a
8.7115(16) A, b = 16.125(3) A, c = 9.6707(19) A, = 99.757(15) ; N-(20-phenylphenyl)male-
˚
˚
˚
imide (6), P21/n, a = 8.519(4) A, b = 13.742(5) A, c = 11.147(4) A, = 92.25(3) ; N-(40-
˚
˚
˚
˚
˚
˚
methoxyphenyl)maleimide (7), P21/n, a = 9.320(3) A, b = 6.621(2) A, c = 16.059(6) A,
=
99.58(3) ; N-(20-trifluoromethylphenyl)-2-methylmaleimide (8), Fdd2, a = 43.362(12)A,
˚
0
˚
˚
b = 8.202(2) A, c = 12.720(4) A; and N-(2 -trifluoromethylphenyl)-2-methanosuccinimide
˚
˚
˚
(9), Cc, a = 7.708(2) A, b = 22.191(9) A, c = 7.137(2) A, = 115.76(2) are described.
Molecules with bulky 20-substituents show larger rotations between the mean phenyl and
maleimide ring planes, and varying degrees of distortion to the imide group.
KEY WORDS: Maleimide; crystal structure; photopolymerization; monomer; conformation.
Introduction
based formulations, a number of N-(substituted)aryl
maleimides and close analogs have been pre-
Recently, it has been shown that N-aliphatic
pared. Of particular interest for their photochem-
ical properties were N-arylmaleimide structures in
which substituents forced the two ring systems
to be nearly perpendicular (ortho substituents) or
imposed no special inter-ring torsional restraints.
Structures and observed and calculated spectro-
scopic properties for N-phenylmaleimide and the
ortho fluoro-, chloro-, bromo-, and iodophenyl
derivatives have already been reported.2 These
structures spanned the inter-ring torsional space.
Structures with well-twisted conformations func-
tion as hydrogen abstracting free-radical photoini-
tiators upon direct excitation in the presence of
a hydrogen atom donor synergist. In the present
work, the structures of eight N-arylmaleimide
compounds are described, six of which bear
ortho-phenyl substituents large enough to produce
maleimides are useful copolymerizable free-radical
photoinitiators by direct or sensitized excitation.1
They are, however, difficult and expensive to pre-
pare compared to N-aromatic maleimides which
have the additional advantages, depending on sub-
stituents, of being less toxic and available in large
quantities from commercial suppliers. To explore
the free-radical photoinitiation properties in acrylic-
(1) Department of Polymer Science, University of Southern
Mississippi, Hattiesburg, Mississippi 39406-0076.
(2) Department of Chemistry, Mississippi College, Clinton,
Mississippi 39058-4036.
(3) Department of Chemistry, Jackson State University, Jackson,
Mississippi 39215.
(4) Becker-Acroma, S19502 Ma¨rsta, Sweden.
* Towhomcorrespondenceshouldbeaddressedate-mailvalente@
mc.edu
563
C
1074-1542/00/0900-0563$18.00/0 2000 Plenum Publishing Corporation

564
Miller, Hoyle, Valente, Zubkowski, and Jo¨nsson
decidedly twisted inter-ring conformations. These are
N-(20-t-butylphenyl)maleimide (1), N-(20-trifluoro-
methylphenyl)maleimide (2), N-(20,60-diisopropyl-
phenyl)maleimide hemibenzene solvate (3), N-
(20,60-diisopropylphenyl)maleimide (unsolvated) (4),
N-(20-bromo-30,50-bis(trifluormethyl)phenyl) malei-
mide (5), N-(20-phenylphenyl)maleimide (6), N-
(40-methoxyphenyl)maleimide (7), N-(20-trifluoro-
methylphenyl)-2-methylmaleimide (8). An analog
in a closely related system, N-(20-trifluoromethyl-
phenyl)-2-methanosuccinimide (9), is also des-
cribed.
Scheme 1.
Table 1. Crystallographic Data for Phenyl Substituted N-Phenylmaleimides 1–7, N-Phenyl-2-methylmaleimide 8, and 2-Methanosuccini-
mide 9
Structure
1
2
3
4
Formula
CCDC no.
Formula weight
Specimen dimensions (mm)
Crystal system
C14H15NO2
1003/5926
229.27
0.60 0.20 0.10
Monoclinic
P21/n
C11H6F3NO2
1003/5927
241.17
0.40 0.40 0.30
Monoclinic
P21/c
C16H29NO2 1/ (C6H6)
1003/5928
296.38
0.30 0.30 0.20
Monoclinic
Pc
C16H19NO2
1003/5929
257.32
0.35 0.10 0.10 mm
Monoclinic
C2/c
2
Space group
Temperature (K)
Cell constants
293(2)
293(2)
292(2)
293(2) K
˚
a (A)
10.197(3)
11.904(4)
10.496(5)
100.61(3)
1252.2(8)
4
11.763(8)
10.699(9)
8.284(5)
90.02(5)
1042.5(12)
4
16.747(6)
8.552(3)
12.899(4)
105.08(3)
1783.7(10)
4
28.146(10)
8.434(4)
12.881(4)
92.20(4)
3055(2)
8
˚
b (A)
˚
c (A)
( )
3
˚
Cell volume (A )
Formula units/cell
3
(Mg m
)
1.216
0.081
1.537
0.142
1.104
0.071
1.119
0.073
calc
1
(mm
)
Decomposition (%)
range( ),
Completeness
3.5(8)
3.0(5)
0.0(1)
+0.0(2)
2.52 → 21.49
92.0
2.6 → 22.5,
2.6 → 27.5
2.38 → 22.50
94.4
94.5
99.9
Index ranges (h, k, l)
0 → 10
0 → 12
11 → 11
1720
0.1433
1630
15 → 15
0 → 13
0 → 10
2548
0.1008
2397
18 → 17
0 → 9
0 → 28
0 → 8
0 → 13
13 → 13
1790
0.0233
1753
Reflections measured
Rmerge
Unique reflections
Observed refl. (I > 2
4491
0.0539
2324
)
972
1103
982
452
l
No. parameters, restraints
Transmission coefficients,
min./max
155, 0
0.99, 0.96
155, 0
0.96, 0.95
200, 0
0.99, 0.98
173, 0
0.99, 0.97
Weights,a a
0.1028
0.1131
0.0936
0.0435
Final R (all data)
R (observed data)
Rw (all data)
0.0833
0.0637
0.1580
0.0971
0.0655
0.1663
0.1099
0.0642
0.1633
0.1396
0.0434
0.0967
S (goodness-of-fit)
0.874
0.776
0.789
0.549
.
3
˚
A
Final 1
(e
)
+0.296, 0.286
+0.311, 0.272
+0.143, 0.152
+0.084, 0.105
(max,min)
Other
E: 0.058(7)
E: 0.041(6)
E: 0.009(2)
E: 0.0023(3)

N-Arylmaleimide derivatives
565
Table 1. continued
Compound
5
6
7
8
9
Formula
CCDC no.
Formula weight
Specimen dimensions (mm)
Crystal system
Space group
C12H4BrF6NO2
1003/5930
388.07
C16H11NO2
1003/5931
249.26
C11H9NO3
1003/5932
203.19
C12H8F3NO2
1003/5933
255.19
C12H8F3NO2
1003/5934
255.19
0.30 0.20 0.05 0.70 0.40 0.30 0.60 0.40 0.30 0.50 0.45 0.30 0.80 0.70 0.60
Monoclinic
P21/n
Monoclinic
P21/n
Monoclinic
P21/n
Orthorhombic
Fdd2
Monoclinic
Cc
Temperature (K)
Cell constants
291(2)
293(2)
293(2)
293(2)
293(2)
˚
a (A)
8.7115(16)
16.125(3)
9.6707(19)
99.757(15)
1338.8(5)
4
8.519(4)
13.742(5)
11.147(4)
92.25(3)
1304.0(9)
4
9.320(3)
6.621(2)
16.059(6)
99.58(3)
977.1(6)
4
43.362(12)
8.202(2)
12.720(4)
90
4524(2)
16
7.708(2)
22.191(9)
7.137(2)
115.76(2)
1099.4(6)
4
˚
b (A)
˚
c (A)
( )
3
˚
Cell volume (A )
Formula units/cell
3
(Mg m
)
1.925
3.147
1.270
0.085
1.381
0.102
1.499
0.135
1.542
0.139
calc
1
(mm
)
Decomposition (%)
range ( )
Completeness (%)
2.0(10)
2.48 → 22.50
98.0
0.8(1)
+2.0(8)
2.37 → 27.52
91.8
15.2(33)
1.88 → 35.00
98.6
+3.5(16)
1.84 → 27.55
99.8
2
2.35 → 25.03
95.6
Index ranges (h, k, l)
0 → 9
8 → 10
16 → 0
8 → 13
2397
0.0373
2301
0 → 12
0 → 69
0 → 13
0 → 20
2619
0.1763
2582
0 → 10
0 → 28
9 → 8
1357
—
1357
0 → 17
10 → 10
1876
0 → 8
20 → 20
2370
0.0678
2245
1372
137, 0
Refl. measured
Rmerge
Unique reflections
Observed refl. (I > 2
No. parameters,
restraints
0.0401
1749
871
)
1142
173, 0
888
164, 1
1214
164, 2
1
200, 0
Transmission coefficients,
0.86, 0.45
0.98, 0.94
0.97, 0.94
0.92, 0.90
0.92, 0.90
min./max
Weights,a
Final R (all data)
R (observed data)
Rw (all data)
S (goodness-of-fit,
all data)
a
0.1193
0.1037
0.0717
0.1800
0.832
0.0588
0.0744
0.0424
0.1002
0.744
0.0788
0.0671
0.0505
0.1283
0.906
0.0943
0.1250
0.0574
0.1454
0.661
0.1328
0.0733
0.0714
0.1689
1.100
Final diff. peaks
+0.797, 1.106
+0.153, 0.142
+0.284, 0.201
+0.319, 0.365
+0.349, 0.392
3
˚
(e .A
Other
)
max,min
E: 0.007(2)
E: 0.015(2)
E: 0.104(8)
E: 0.0008(2)
E: 0.021(7)
Note: Estimated standard deviations in parentheses.
2
(F
aWeights are taken as 1/
+ (aP)2, where P = max(Fo2, 0) + 2Fc2/3.
2
)
o
bOther: E = Extinction coefficient x, where Fc is multipled by (1 + 0.001 (Fc)2( 3)/sin(2 ))
.
1/4
Experimental
Reagents and solvents were obtained from
Aldrich Chemical Co., and were of the highest avail-
able purity. N-Aryl maleimides were prepared by a
general procedure in which an equimolar quantity of
a substituted arylamine was added to maleic anhy-
dride in ethoxyethane. Reactions were carried out
at room temperature, unless the substitutent on the
aryl amine was electron-donating (methoxy, i-propyl,
t-butyl, phenyl) in which case the solution was cooled
to 0 C during addition. Substituted maleamic acids
precipitated after a few hours and were recovered
in 90–98% yield by filtration. Maleamic acids
were then dehydrated by heating to 130 C
and water was removed from solutions in (4:1)
toluene:dimethylsulfoxide to which a small amount
of concentrated sulfuric acid had been added.

566
Miller, Hoyle, Valente, Zubkowski, and Jo¨nsson
Table 2. Atomic Coordinates
Isotropic Displacement Parameters (A
(
104) and Equivalent
Table 4. Atomic Coordinates ( 104) and Equivalent Isotropic
Displacement Parameters (A
2
2
103) for N-(20-t-
103) for N-(20,60-di-i-Propyl-
˚
˚
Butylphenyl)Maleimide (1)
phenyl)Maleimide Hemibenzene Solvate (3)
a
a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
O1
O2
N1
C1
C2
C3
C4
C11
C12
C13
C14
C15
C16
C21
C22
C23
C24
617(3)b
39(3)
758(3)
1506(2)
3917(2)
2729(2)
1950(3)
1807(3)
2496(3)
3166(3)
3289(3)
2932(3)
3560(3)
4455(3)
4773(3)
4175(3)
1748(4)
853(3)
11155(3)
7749(3)
9481(3)
10161(4)
9379(4)
8397(4)
8423(3)
10042(3)
9799(3)
10453(4)
11242(4)
11465(4)
10834(4)
8933(5)
9306(5)
7517(4)
8909(4)
69(1)
67(1)
44(1)
50(1)
61(1)
58(1)
48(1)
46(1)
45(1)
61(1)
70(1)
71(1)
59(1)
83(1)
78(1)
80(1)
54(1)
O1
O2
N1
C1
C2
C3
C4
C11
C12
C13
C14
C15
C16
C21
C22
C23
C31
C32
C33
C1S
C2S
C3S
2583(2)b
4023(2)
3157(2)
3058(3)
3615(2)
4038(2)
3770(2)
2726(2)
3030(3)
2608(3)
1945(4)
1661(2)
2043(2)
3772(3)
3519(5)
4479(4)
1715(2)
929(3)
7451(5)
4197(3)
5941(3)
6441(6)
5477(6)
4550(5)
4808(5)
6517(5)
7851(5)
8377(5)
7543(8)
6257(7)
5705(5)
8756(5)
10326(7)
8776(8)
4286(6)
4620(7)
2901(6)
10168(18)
10815(10)
10659(10)
220(2)
2804(2)
1699(2)
648(3)
201(3)
953(3)
153(2)
102(1)
73(1)
99(1)
107(2)
98(1)
77(1)
74(1)
94(1)
115(2)
125(2)
110(1)
87(1)
120(2)
277(4)
231(4)
105(1)
168(2)
174(2)
167(3)
158(2)
165(3)
123(4)
1239(4)
1405(4)
174(4)
1939(3)
2439(3)
3019(3)
3763(3)
3911(4)
3325(3)
2566(3)
2868(4)
2360(8)
3884(5)
1899(3)
1042(3)
2561(4)
4146(12)
5061(19)
5920(10)
1986(3)
3230(3)
4316(4)
4159(5)
2905(5)
1837(4)
4938(4)
2870(4)
2817(4)
3445(3)
2245(4)
1966(3)
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
1561(4)
280(13)
690(4)
bEstimated standard deviations in parentheses.
410(12)
Then, after removing most of the toluene by dis-
tillation, water was added to the cooled solutions
and the N-aryl maleimides precipitated and were
recovered by filtration. Recrystallization from
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
bEstimated standard deviations in parentheses.
various low polarity solvents produced specimens
suitable for single crystal diffraction analysis.
Compounds are colorless except for 7 which was
yellow.
Table 3. Atomic Coordinates
Isotropic Displacement Parameters (A
(
104) and Equivalent
2
103) for N-(20-
˚
Trifluoromethylphenyl)Maleimide (2)
a
Atom
x
y
z
Ueq
Crystallography
F1
F2
F3
O1
O2
N1
C1
C2
3709(2)b
3041(2)
2571(2)
2331(2)
3784(2)
2818(2)
2987(2)
4112(2)
4541(2)
3723(2)
1826(2)
1793(2)
803(3)
11328(2)
9935(2)
11811(2)
7402(2)
10455(2)
9158(2)
7956(2)
7557(3)
8435(3)
9489(2)
9908(2)
10794(2)
11500(2)
11306(3)
10437(3)
9734(2)
10969(3)
336(3)
1193(2)
1537(3)
723(2)
3931(3)
2176(2)
1567(3)
2183(3)
3110(3)
3170(3)
1930(3)
698(3)
127(1)
112(1)
136(1)
71(1)
91(1)
51(1)
53(1)
64(1)
67(1)
61(1)
49(1)
57(1)
74(1)
80(1)
75(1)
63(1)
76(1)
Table 1 contains a summary of the crystal data
and data collection parameters. Intensity data were
collected on a Siemens R3m/v automated diffrac-
tometer with graphite monochromatized MoK ra-
˚
diation ( = 0.71073 A) using omega scans. Three
C3
C4
standards were monitored every 197 reflections. Data
were corrected for Lorentz, polarization, and de-
cay effects but not for absorption. Structures were
solved by direct methods3 and the modeled non-
H-atom positions and associated anisotropic vibra-
tional tensor elements were refined by full-matrix
least-squares4 using all data and minimizing differ-
ences in F2. Atom form factors are those from the
International Tables of Crystallography.5 Hydrogen
atoms were assigned calculated positions and allowed
to ride on their attached atoms with an isotropic
C11
C12
C13
C14
C15
C16
C17
521(3)
117(3)
69(2)
909(2)
2764(3)
1527(4)
2717(4)
2919(3)
404(4)
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
bEstimated standard deviations in parentheses.

N-Arylmaleimide derivatives
567
Table 5. Atomic Coordinates ( 104) and Equivalent Isotropic
Table 7. Atomic Coordinates
Isotropic Displacement Parameters (A
(
104) and Equivalent
2
2
103)
for
N-(20,60-di-i-
103) for N-(20-
˚
˚
Displacement
Parameters
(A
Propylphenyl)Maleimide (Unsolvated) (4)
Phenylphenyl)Maleimide (6)
a
a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
N1
O1
O2
C1
C2
C3
C4
C11
C12
C13
C14
C15
C16
C21
C22
C23
C24
C25
C26
507(2)b
2462(2)
1595(2)
1374(3)
677(4)
475(3)
656(3)
744(2)
163(2)
2219(1)
3356(1)
1362(1)
3023(2)
3338(2)
2749(2)
2009(2)
1692(1)
2063(1)
1534(2)
669(2)
4487(1)
4235(2)
5321(2)
4814(2)
5992(2)
6320(2)
5379(2)
3391(2)
2328(2)
1283(2)
1299(2)
2360(2)
3407(2)
2291(2)
1526(2)
1451(2)
2110(2)
2871(2)
2967(2)
49(1)
92(1)
80(1)
64(1)
86(1)
77(1)
58(1)
47(1)
47(1)
58(1)
62(1)
63(1)
58(1)
47(1)
60(1)
71(1)
65(1)
66(1)
57(1)
O1
O2
N1
C1
C2
C3
C4
C11
C12
C13
C14
C15
C16
C21
C22
C23
C31
C32
C33
3577(2)b
4442(1)
3930(2)
3846(2)
4181(2)
4438(2)
4285(2)
3687(2)
3858(3)
3627(3)
3247(3)
3076(2)
3295(2)
4150(3)
4287(3)
4669(2)
3004(2)
3107(2)
2675(2)
2536(6)
700(4)
1021(5)
1544(9)
578(7)
8836(3)
6825(2)
7599(3)
8616(5)
9271(4)
8701(4)
7580(4)
6684(4)
6234(5)
5335(6)
4919(6)
5363(5)
6286(4)
7083(6)
6677(5)
5927(5)
6092(5)
6815(4)
7421(4)
168(2)
106(1)
82(1)
112(2)
111(2)
102(2)
81(2)
363(6)
98(7)
1621(8)
2959(9)
3532(9)
2708(12)
1365(9)
764(9)
5466(9)
3859(9)
3988(10)
2020(7)
670(8)
84(2)
106(2)
136(2)
149(3)
119(2)
92(2)
314(6)
145(3)
271(5)
201(3)
106(2)
190(3)
490(2)
1326(3)
1866(3)
1592(2)
790(2)
319(2)
832(1)
2971(1)
3724(2)
4548(2)
4622(2)
3881(2)
3061(2)
362(3)
1278(3)
2677(3)
3106(3)
2180(2)
313(7)
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
bEstimated standard deviations in parentheses.
bEstimated standard deviations in parentheses.
Table 6. Atomic Coordinates ( 104) and Equivalent Isotropic
Displacement Parameters (A
displacement factor equal to 120% of the equivalent
isotropic displacement factor of the attached non-H-
atom. Atom positions and equivalent isotropic dis-
placement parameters are given for the structures in
2
103) for N-(20-bromo-30,50-di
˚
(Trifluoromethyl)Phenyl)Maleimide (5)
a
Atom
x
y
z
Ueq
Br
F1
F2
F3
F4
F5
F6
O1
O2
N1
C1
C2
C3
1843(2)b
3074(10)
601(10)
1511(9)
3085(11)
716(11)
2007(15)
4764(12)
501(12)
2131(11)
3490(2)
3039(18)
1558(17)
840(2)
1978(12)
1939(12)
1829(11)
1844(11)
1937(12)
2049(13)
1756(18)
1919(17)
2692(1)
4251(4)
4161(4)
4485(4)
2181(7)
2153(6)
1083(5)
1006(6)
740(6)
1005(5)
751(7)
119(8)
52(8)
624(8)
1652(6)
2461(6)
3101(6)
2895(6)
2084(6)
1445(6)
3976(7)
1852(9)
3258(1)
5362(8)
4687(7)
6807(7)
10294(8)
9914(8)
9739(8)
4704(10)
3912(11)
4647(9)
4247(12)
3106(13)
2905(12)
3816(12)
5587(10)
5187(9)
6154(10)
7535(10)
7948(9)
6988(11)
5740(12)
9478(11)
74(1)
87(2)
85(3)
73(2)
136(4)
116(3)
158(5)
80(3)
89(3)
43(2)
60(4)
73(4)
72(4)
69(4)
38(3)
39(3)
35(3)
40(3)
39(3)
48(3)
60(4)
59(4)
Table 8. Atomic Coordinates
Isotropic Displacement Parameters (A
(
104) and Equivalent
2
103) for N-(40-
˚
Methoxyphenyl)Maleimide (7)
a
Atom
x
y
z
Ueq
O1
O2
O3
N1
C1
C2
C3
C4
C11
C12
C13
C14
C15
C16
C17
1239(2)
400(2)
2284(1)
143(1)
908(2)
1246(2)
782(2)
91(2)
4830(2)
390(2)
2198(1)
3919(1)
307(1)
72(1)
85(1)
61(1)
47(1)
51(1)
60(1)
64(1)
56(1)
42(1)
48(1)
49(1)
46(1)
51(1)
49(1)
68(1)
1499(2)
2041(2)
3859(2)
4246(3)
2746(3)
1233(3)
1102(2)
739(2)
1667(2)
719(2)
1122(2)
2039(2)
3288(3)
2894(1)
2833(1)
3691(1)
4180(1)
3693(1)
2222(1)
1911(1)
1268(1)
939(1)
C4
C11
C12
C13
C14
C15
C16
C17
C18
459(2)
56(2)
520(2)
1629(2)
2156(2)
1575(2)
1684(2)
1263(1)
1903(1)
104(1)
aUeq is defined as one third of the trace of the orthogonalized
Ui j tensor.
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
bEstimated standard deviations in parentheses.
bEstimated standard deviations in parentheses.

568
Miller, Hoyle, Valente, Zubkowski, and Jo¨nsson
Table 9. Atomic Coordinates ( 104) and Equivalent
Isotropic Displacement Parameters (A
Table 10. Atomic Coordinates
Isotropic Displacement Parameters (A
(
104) and Equivalent
2
2
103) for N-(20-
103) for N-(20-
˚
˚
Trifluoromethylphenyl)-2-Methylmaleimide (8)
Trifluoromethylphenyl)-2-Methanosuccinimde (9)
a
a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
F1
F2
F3
O1
O2
N1
C1
C2
C3
C4
C5
C11
C12
C13
C14
C15
C16
C21
3972(1)b
4450(1)
4123(1)
4991(1)
4222(1)
4549(1)
4850(1)
4964(1)
4742(1)
4467(1)
5277(1)
4347(1)
4165(1)
3970(1)
3949(1)
4129(1)
4330(1)
4179(1)
5248(3)
4956(3)
4304(3)
2424(4)
821(4)
1608(4)
2170(4)
2332(4)
1833(4)
1347(4)
2943(5)
1300(4)
2569(4)
2219(4)
663(4)
3030(2)
2733(2)
1560(2)
2592(2)
408(2)
1740(2)
1803(2)
687(2)
62(3)
677(2)
445(3)
2613(2)
3030(2)
3854(2)
4251(3)
3832(3)
3020(3)
2587(3)
80(1)
83(1)
90(1)
63(1)
68(1)
44(1)
45(1)
47(1)
52(1)
47(1)
67(1)
39(1)
40(1)
48(1)
55(1)
52(1)
47(1)
55(1)
F1
F2
F3
O1
O2
N1
C1
C2
C3
C4
C5
C11
C12
C13
C14
C15
C16
C21
12285(5)b
12284(4)
12577(4)
9489(5)
10102(6)
9617(4)
9945(5)
10942(6)
11282(7)
10298(6)
11332(8)
8566(5)
9505(5)
8437(6)
6456(6)
5523(5)
6585(5)
11662(6)
426(2)
1363(2)
750(2)
2467(1)
960(1)
1620(1)
2227(2)
2492(2)
1988(2)
1452(2)
3064(2)
1217(1)
825(2)
4475(6)
3926(6)
1805(5)
1184(6)
2825(6)
618(5)
81(1)
76(1)
82(1)
56(1)
61(1)
37(1)
39(1)
43(1)
54(1)
44(1)
53(1)
32(1)
35(1)
42(1)
45(1)
43(1)
39(1)
45(1)
42(6)
1246(7)
2456(8)
2073(6)
1246(8)
67(5)
1748(5)
2315(6)
1220(7)
443(6)
427(2)
409(2)
798(2)
1200(2)
841(2)
569(4)
240(4)
4260(4)
1002(6)
2979(6)
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
aUeq is defined as one third of the trace of the orthogonalized Ui j
tensor.
bEstimated standard deviations in parentheses.
bEstimated standard deviations in parentheses.
Table 2 through 10. Plots of the molecular structures
are given in Figs. 1 through 9. Three of the structures
(3, 8, 9) were found in noncentrosymmetric space
groups.
----
Bond lengths for N Caryl in 1–9 range from 1.406 to
˚
˚
1.446 A, and average 1.435 A. This average is sim-
ilar to that for (unsubstituted) N-phenylmaleimide2
˚
(1.430 A), and the distribution is not a function of
the inter-ring torsion angle (see Table 11), though the
high rotation angles between the two rings effectively
isolates the phenyl ring from imide N electron dona-
Discussion
----
tion. The average N Caryl bond length is slightly
Focusing on the common features, each com-
pound is an N-arylimide (maleimide or succinimide).
----
long compared to those in planar Caryl Nsp2 C2
Table 11. Selected Geometrical Features in N-phenylmaleimide and Derivatives 1–9 as a Function of o-Substituents
Compound
N- PhMa
1
2
3
4
5
6
7
8
9
20-subst.
60-subst.
Caryl-N (A)
H
H
1.435
49.5
t-butyl
H
1.446
88.7
CF3
H
1.431
i-Pr
i-Pr
1.426
i-Pr
i-Pr
1.432
Br
H
1.406
C6H5
H
1.429
79.6
H
H
1.438
CF3
H
1.435
CF3
H
1.427
˚
Imide/phenyl
96.1
84.5
85.4
88.9
63.7
85.5
85.5
Interplanar angleb( )
Mean dev. from
imide plane (A)
0.014
0.027
0.059
0.118
0.012
0.025
0.005
0.011
0.006
0.012
0.026
0.052
0.003
0.006
0.006
0.011
0.003
0.005
0.012
0.025
b
˚
N1 dev. from imide
c
˚
plane (A)
aN-Phenyl maleimide (see reference 2).
bImide plane described by N1, C1, C4, C11; imide ring by these plus C2, C3; phenyl plane described by C11–C16. Esd’s for distances
˚
.0.006A, for angles .0.400 .
c
0
˚
Positive value away from 2 -substituent; negative value toward 2 -substituent; esd’s .0.008 A.

N-Arylmaleimide derivatives
569
Fig. 3. Ellipsoid plot (30% probability enclosures) for 3 (excluding
solvent).
Fig. 1. Ellipsoid plot (50% probability enclosures) for 1.
tures. This is supported by the slight contraction of
˚
---- ==
the adjacent N C( O) in 1–8 to 1.395 A (range
˚
6
1.366–1.402 A, 16 cases) compared to those
˚
cases (1.37A: average from 16 structures). Car-
bonyl groups adjacent to N must to some extent
remove electron density from N, as represented
by contributions from charged resonance struc-
˚
----
in
N
Csp2 unsaturated imides (1.409 A: av-
---- ==
erage of 28 cases).6 The
N
C( O) lengths
˚
(1.400, 1.402 A) in the N-aryl succinimide (9)
Fig. 2. Ellipsoid plot (50% probability enclosures) for 2.
Fig. 4. Ellipsoid plot (30% probability enclosures) for 4.

570
Miller, Hoyle, Valente, Zubkowski, and Jo¨nsson
Fig. 5. Ellipsoid plot (50% probability enclosures) for 5.
are longer.
Fig. 7. Ellipsoid plot (50% probability enclosures) for 7.
having a single ortho substituent (1, 2, 5, 6, 8, 9), nitro-
gen is systematically distorted from the imide plane.
˚
In the o-bromo case (5), N is displaced 0.052 Aout of
the imide plane away from Br. In the o-(t-butyl) (1),
Scheme 2.
Imide groups (defined as N1, C1, C4, and C11)
are essentially planar (see Table 11). For the imides
Fig. 6. Ellipsoid plot (50% probability enclosures) for 6.
Fig. 8. Ellipsoid plot (50% probability enclosures) for 8.

N-Arylmaleimide derivatives
571
mean substituted phenyl ring plane is rotated 57.1
with respect to the N-phenyl ring mean plane, and its
two ortho carbons essentially straddle the nitrogen.
In the two 20,60-diisopropyl examples, the least bulky
part (methine H) of each isopropyl group is directed
˚
toward the nitrogen which is about 0.01 A from the
imide plane.
As can be seen from inspection of Table 11, the
N-phenyl ring and imide rings are strongly rotated
with respect to each other. The rotation is smallest
in the single case without an ortho substituent (7),
otherwise this torsion is above 80 . This is consistent
with other maleimides with bulky ortho substituents,
where structures with a minimum in inter-ring tor-
sional energy have conformations with the rings per-
pend icular.2
Fig. 9. Ellipsoid plot (50% probability enclosures) for 9.
Acknowledgments
WethankFirstChemicalCorporationandFusion
UV-Curing Systems (CWM & CEH), and the Office
of Naval Research (EJV & JDZ).
o-CF3 (2, 8, 9) and o-phenyl (6) cases, the second
atoms of the o-substituent straddle the N, which is
displaced by 0.006 – 0.118 A out of the imide plane
˚
toward the substituent.
References
1. Hoyle, C.E.; Viswanathan, D.; Clark, S.C.; Miller, C.W.;
Nguyen, S.; Jo¨nsson, S.; Shao, L. Macromolecules 1999, 32,
2793.
2. Miller, C.W.; Hoyle, C.E.; Valente, E.J.; Magers, D.H.; Jo¨nsson,
S. J. Phys. Chem. A 1999, 103, 6406.
3. Sheldrick, G. SHELXS-93. Acta Crystallogr. 1990, A46, 467.
4. Sheldrick, G. SHELXL-97. Program for the Refinement of
Crystal Structure from X-Ray Diffraction Data; University of
Go¨ttingen, Go¨ttingen, Germany, 1997.
Scheme 3.
5. International Tables for X-Ray Crystallography, Volume IV;
Kluwer Academic Publishers, Dordrecht, Holland, 1989.
6. Burgi, H.-B.; Dunitz, J. D. “Structure Correlation,” Appendix A;
VCH, New York, 1994.
It is interesting to note that the two severest cases
of imide N distortion (1, 5) represent the extremes
----
in Caryl N bond lengths. In the phenyl case (6), the