Structure and properties of N-phenylmaleimide derivatives

Article abstract of DOI:10.1023/A:1009571214760

The crystal structures of 2-chloro-N-phenyl-triphenylphosphoranaminomaleimide 1, N-phenyl-di(triphenylphosphoranamino)maleimide 2a, a nitromethane solvate 2b, N-phenyl-2,3-dithiomaleimide 3, and N-phenyl-2,3-di(thiophenyl)maleimide have been determined. 1 crystallizes in space group P-1 with cell dimensions a = 10.432(6), b = 14.661(5), c = 9.376(4) A, α = 93.13(4), β = 92.09(5), and γ = 79.08(4)^o, 2a crystallizes in space group P2₁/c with cell dimensions a = 11.272(2), b = 28.910(7), c = 12.702(2) A, and β = 115.31(2)^o, 2b crystallizes in space group P-1 with cell dimensions a = 13.140(2), b = 13.796(3), c = 11.755(3) A, α = 99.62(2), β = 100.23(2), and γ = 102.74(2)^o, 3 crystallizes in space group C2/c with cell dimensions a = 42.926(5), b = 5.757(6), c = 8.259(3) A, and β = 99.71(3)^o, and 4 crystallizes in space group C2/c with cell dimensions a = 20.055(4), b = 10.370(6), c = 18.690(7) A, and β = 100.32(2)^o. Vicinal diazides of five-membered rings undergo the normal Staudinger reaction to form triphenylphosphoranamino derivatives. Compounds 1 and 2 fluoresce strongly, but nitromethane quenches the fluorescence of 2.

Full text of DOI:10.1023/A:1009571214760

Journal of Chemical Crystallography, Vol. 29, No. 1, 1999
Structure and properties of N-phenylmaleimide derivatives
(
1)
(1)
(1)
Satish G. Bodige, Miguel A. M e´ ndez-Rojas, and William H. Watson *
Received July 8, 1998
The crystal structures of 2-chloro-N-phenyl-triphenylphosphoranaminomaleimide 1, N-phe-
nyl-di(triphenylphosphoranamino)maleimide 2a, a nitromethane solvate 2b, N-phenyl-2,3-
dithiomaleimide 3, and N-phenyl-2,3-di(thiophenyl)maleimide have been determined. 1 crys-
tallizes in space group P-1 with cell dimensions a ϭ 10.432(6), b ϭ 14.661(5), c ϭ 9.376(4)
˚
1
A, Ͱ ϭ 93.13(4), ͱ ϭ 92.09(5), and Ͳ ϭ 79.08(4)Њ, 2a crystallizes in space group P2 /c with
˚
cell dimensions a ϭ 11.272(2), b ϭ 28.910(7), c ϭ 12.702(2) A, and ͱ ϭ 115.31(2)Њ, 2b
crystallizes in space group P-1 with cell dimensions a ϭ 13.140(2), b ϭ 13.796(3), c ϭ 11.755(3)
˚
A, Ͱ ϭ 99.62(2), ͱ ϭ 100.23(2), and Ͳ ϭ 102.74(2)Њ, 3 crystallizes in space group C2/c with
˚
cell dimensions a ϭ 42.926(5), b ϭ 5.757(6), c ϭ 8.259(3) A, and ͱ ϭ 99.71(3)Њ, and 4
crystallizes in space group C2/c with cell dimensions a ϭ 20.055(4), b ϭ 10.370(6), c ϭ
˚
1
8.690(7) A, and ͱ ϭ 100.32(2)Њ. Vicinal diazides of five-membered rings undergo the normal
Staudinger reaction to form triphenylphosphoranamino derivatives. Compounds 1 and 2
fluoresce strongly, but nitromethane quenches the fluorescence of 2.
KEY WORDS: N-phenylmaleimide structures; fluorescence; Staudinger reaction; triphenylphosphora-
namines; thiols.
Introduction
pounds prepared from 2,3-dichloro-N-phenylma-
leimide.
Recently, we described the reaction of triphenyl-
Reaction with one equivalent of azide ion leads
to compound 1, while reaction with two equivalents
of azide gives the di-Staudinger product 2. Recrystal-
lization from DMF produced crystals containing 50
phosphine with the vicinal diazides of benzoquinone
1
,2
forming unusual 2-amino-1,2,3-triazole derivatives.
In contrast, the five-membered ring 2,3-diaza-N-
methylmaleimide yields the normal Staudinger prod-
˚
3
Ϫ3
A voids in the structure (2a, d ϭ 1.285 g cm ).
3
uct when reacted with triphenylphosphine. During
Recrystallization from nitromethane gave a 1 : 1 sol-
Ϫ3
this investigation we prepared a number of malei-
mide derivatives to test our hypothesis concerning
the mechanism of the vicinal diazide reaction. It was
noted that many of these compounds exhibit strong
fluorescence upon exposure to UV light. Maleimide
derivatives have been used extensively as fluores-
cence probes, in energy transfer investigations, as
components of biologically active molecules, and as
vate (2b, d ϭ 1.305 g cm ). The structures of both
crystals are reported. Reaction of 2,3-dichloro-N-
phenylmaleimide with benzyl mercaptan in refluxing
ethanol yielded the dithiol 3. The same compound
was obtained by reacting 2,3-dichloro-N-phenylma-
leimide directly with NaSH, but the product was
more difficult to purify. Metal complexes with a
variety of N-substituted dithiomaleimide ligands
are being investigated at the present time. Reaction
with thiophenol yielded the thioether 4, which is sta-
ble under reflux. Compounds 1, 2a, and 3 fluoresce
strongly, but 2b and 4 do not. Halogen substitution
at the para-position in 2 also quenches the fluores-
cence.
4
–8
intermediates in organic syntheses. We would like
to report the structures and properties of several com-
(
1)
Department of Chemistry, Texas Christian University, Box
98660, Fort Worth, Texas 76129.
To whom correspondence should be addressed.
2
*
57
1074-1542/99/0100-0057$16.00/0  1999 Plenum Publishing Corporation

5
8
Bodige, M e´ ndez-Rojas, and Watson
Experimental
Starting materials were used as purchased with-
Atomic positional parameters are given in Tables 2–6
for compounds 1, 2a, 2b, 3, and 4, while selected
interatomic distances and valence angles are given
in Tables 7 and 8. Figures 1–5 are thermal ellipsoid
plots for the five compounds. Cyclic voltammetry
measurements were made in acetonitrile with tetra-
methylammonium hexaflurophosphate as supporting
electrolyte and a Model 173 potentiostat/Galvanostat
coupled to a Model 175 Universal Programmer
(EG&G, Princeton Applied Research). Ferrocene
was used as an internal reference with E1/2 ϭ ϩ400
out further purification. Solvents were dried follow-
ing standard procedures. IR spectra were recorded
1
on a Midac Systems FTIR using KBr pellets; H NMR
spectra were recorded on a Varian XL-300 spectrom-
eter in CD Cl; mass spectra were obtained using a
3
Finnigan quadrapole spectrometer; UV-Visible ab-
sorption spectra were recorded with a HP-8542A
UV-Vis diode array spectrophotometer, extinction
coefficients were measured on a Cary 3, while steady-
state photoluminescence (PL) measurements were
made using a Spex Fluorolog-2 spectrometer at an
excitation wavelength of 375 nm. All X-ray data were
collected on a Rigaku AFC-6S diffractometer using
the Ͷ-2␪ mode at a fixed scan rate with multiple scans
for weak reflections. All structures were solved by
1
3
V vs NHE. All scans were irreversible and multiple
scans resulted in the appearance of peaks due to
product formation. Only cathodic (Ep
(Ep ) peak values are reported.
c
) or anodic
a
2,3-Dichloro-N-phenylmaleimide (3,4-dichloro-1-
phenyl-3-pyrroline-2,5-dione)
9,10
direct methods and refined and analyzed using
1
1
12
TEXSAN and PLATON. Crystal, intensity mea-
surement, and refinement data are given in Table 1.
To a stirred solution of 2,3-dichloromaleic anhy-
dride (1.66 g, 10 mmol) in 20 mL of ether, 0.92 g (10
Table 1. Crystal, Structure Solution and Refinement Data for Compounds 1, 2a, 2b, 3, and 4
1
2a
2b
3
4
и
и
2
Formula
C
C
28
H
20
O
2 2
N PCl
C
46
H
O N P
35 2 3 2
C
46
H
35
O
2
N
3
P
C
10 7 2
H O NS
2
C H
22 15
O NS
2 2
3
7
H NO
3 2
CH NO
CCDC deposit no.
F.W.
CCDC-1003/5461
555.98
CCDC-1003/5462
723.75
CCDC-1003/5463
784.70
CCDC-1003/5464
237.29
CCDC-1003/5465
389.49
Color
yellow
red
red
colorless
yellow
Habit
prismatic
prismatic
prismatic
prismatic
prismatic
Dimensions (mm)
Crystal system
Space group
0.90 ϫ 0.80 ϫ 0.70 0.60 ϫ 0.70 ϫ 0.90 0.20 ϫ 0.20 ϫ 0.20 0.60 ϫ 0.70 ϫ 0.80 0.50 ϫ 0.70 ϫ 0.90
triclinic
P-1
monoclinic
P2 /c
triclinic
P-1
monoclinic
C2/c
monoclinic
C2/c
1
˚
a, A
10.432(6)
14.661(5)
9.376(4)
93.13(4)
92.09(5)
79.08(4)
1405(1)
2
11.272(2)
28.910(7)
12.702(2)
90.00
115.31(1)
90.00
13.140(2)
13.796(3)
11.755(3)
99.62(2)
100.23(2)
102.74(2)
1997.5(7)
2
42.926(5)
5.757(6)
8.259(3)
90.00
99.71(3)
90.00
20.055(4)
10.370(6)
18.690(7)
90.00
100.32(2)
90.00
˚
b, A
˚
c, A
Ͱ, Њ
ͱ, Њ
Ͳ, Њ
˚
3
V, A
3742(1)
4
2012(2)
8
3824(2)
8
Z
D
calc(g cmϪ3)
1.314
1.285
1.305
1.567
1.353
˚
␭(A)
0.71069
2.30
1.54178
13.96
1.54178
13.95
0.71069
5.04
0.71069
2.95
Ϫ1
Ȑ(cm )
Transmission factors
2␪max(Њ)
0.589–1.00
55.0
0.843–1.000
124.0
0.765–0.997
157.4
0.933–0.996
55.2
0.979–0.999
55.0
Total reflections
Unique reflections
Direct methods
6810
6452
SIR92
2626
6067
5737
SHELXS
3162
7764
7401
SIR92
4403
2597
2563
SIR92
1029
4774
4641
SIR92
1657
Reflections (I Ն 3␴)
R,R
Parameters
w
0.066;0.057
353
0.050;0.039
478
0.057;0.046
514
0.063;0.063
137
0.055;0.039
244
(⌬/␴)max
0.00
0.00
0.00
0.00
0.00
␳
min;␳max
Ϫ0.37;0.42
Ϫ0.30;0.33
Ϫ0.33;0.54
Ϫ0.58;0.50
Ϫ0.29;0.25

N-phenylmaleimide derivatives
59
Table 2. Atomic Coordinates and Biso/Beq for compound 1
Atom
x
y
z
B
eq
Cl(1)
P(1)
O(1)
O(2)
O(3)
N(1)
N(2)
N(3)
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)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(30)
C(32)
C(33)
H(1)
1.06482(9)
0.69905(8)
0.7177(2)
1.0515(2)
0.3430(3)
0.8783(2)
0.8319(2)
0.2357(3)
0.8100(3)
0.8698(3)
0.9635(3)
0.9754(3)
0.8522(3)
0.8374(3)
0.8075(4)
0.7950(4)
0.8121(4)
0.8409(3)
0.5554(3)
0.4786(3)
0.3788(3)
0.3593(3)
0.4363(3)
0.5331(3)
0.7004(3)
0.5866(3)
0.5861(3)
0.7012(4)
0.8125(3)
0.8140(3)
0.6828(3)
0.5657(3)
0.5636(4)
0.6765(4)
0.7915(4)
0.7968(3)
0.3327(4)
0.2309(4)
0.1342(5)
0.8498
0.22079(5)
0.25198(5)
0.4484(1)
0.4359(1)
0.0647(2)
0.4704(1)
0.2483(2)
Ϫ0.0527(2)
0.4190(2)
0.3156(2)
0.3171(2)
0.4082(2)
0.5697(2)
0.6213(2)
0.7165(2)
0.7616(2)
0.7110(2)
0.6161(2)
0.2818(2)
0.3719(2)
0.3914(2)
0.3259(2)
0.2386(2)
0.2183(2)
0.1356(2)
0.1126(2)
0.0248(2)
Ϫ0.0423(2)
Ϫ0.0194(2)
0.0687(2)
0.3185(2)
0.3400(2)
0.3809(2)
0.3991(2)
0.3757(3)
0.3355(2)
Ϫ0.0081(3)
Ϫ0.1391(3)
Ϫ0.0197(3)
0.5857
0.1844(1)
0.5028(1)
0.4573(2)
0.1513(2)
0.9198(4)
0.3054(3)
0.4199(3)
0.9458(3)
0.3838(3)
0.3550(3)
0.2623(3)
0.2257(3)
0.3059(3)
0.4360(4)
0.4373(4)
0.3119(4)
0.1837(4)
0.1801(4)
0.3885(3)
0.3944(4)
0.2894(4)
0.1839(4)
0.1801(4)
0.2824(4)
0.5528(3)
0.6037(4)
0.6485(4)
0.6436(4)
0.5987(4)
0.5527(4)
0.6738(3)
0.7399(4)
0.8794(4)
0.9473(4)
0.8784(4)
0.7424(4)
0.9684(5)
1.0090(5)
0.8474(5)
0.5270
4.41(2)
2.85(2)
4.33(6)
4.14(6)
9.3(1)
2.95(6)
3.11(6)
5.08(9)
2.87(8)
2.61(7)
2.66(7)
2.97(8)
2.94(8)
3.92(9)
5.0(1)
5.0(1)
4.8(1)
3.99(9)
2.68(7)
3.38(8)
4.5(1)
4.15(9)
4.02(9)
3.62(8)
2.63(7)
3.88(9)
4.6(1)
4.7(1)
5.3(1)
4.42(9)
2.90(8)
4.01(9)
5.3(1)
5.6(1)
5.4(1)
3.74(9)
6.6(1)
8.1(1)
8.9(2)
4.245
mmol) of aniline was added with stirring. A white
solid precipitated and was separated by filtration. The
isolated crude solid was dissolved in a solution of
2-Chloro-N-phenyl-
triphenylphosphoranaminomaleimide (1)
0
.700 g of sodium acetate and 7 mL of acetic anhy-
To a solution of 2,3-dichloro-N-phenylmalei-
mide (1.21 g, 10 mmol) in 20 mL of ethanol was
added 0.35 g (5 mmol) of sodium azide. The mixture
was stirred for 1 h at room temperature with the
colorless slurry becoming yellow. Triphenylphos-
phine (1.37 g, 5 mmol) was added and stirred for 1
h. Removal of solvent gave 0.760 g of a yellow solid
(yield 35%). Recrystallization from DMF gave yellow
dride. The resulting solution was poured into 50 mL
of ice water yielding 1.45 g (yield 60%) of a pale
brown-yellow compound m.p. 201–202ЊC. H NMR:
ͳ, 7.495–7.256 (5H, phenyl multiplet): UV (CHCl
1
3
):
2
␭
max ϭ 320 nm, ␧max ϭ 1.6 ϫ 10 . Excitation at 350 nm
gives an emission maximum at 514 nm with a shoulder
at 633 nm. Monitoring at 514 nm gave an excitation
maximum at 395 nm, while monitoring the shoulder
at 633 nm gave excitation maxima at 303 and 369 nm.
1
crystals of a DMF solvate, m.p. 226–228ЊC. H NMR:
ͳ, 7.199–8.015 (20H, multiplets consistent with four

6
0
Bodige, M e´ ndez-Rojas, and Watson
Table 3. Atomic Coordinates and Beq for compound 2a
Atom
x
y
z
B
eq
P(1)
P(2)
O(1)
O(2)
N(1)
N(2)
N(3)
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)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
0.65601(8)
0.29049(8)
0.8654(2)
0.4651(2)
0.6797(2)
0.7166(2)
0.4331(2)
0.7524(3)
0.6664(3)
0.5445(3)
0.5512(3)
0.7246(3)
0.8378(3)
0.8815(3)
0.8113(4)
0.6979(4)
0.6546(3)
0.7913(3)
0.8790(3)
0.9894(4)
1.0123(4)
0.9256(4)
0.8152(3)
0.5437(3)
0.5183(4)
0.4312(4)
0.3719(4)
0.3968(4)
0.4817(3)
0.5774(3)
0.6242(3)
0.5742(4)
0.4751(4)
0.4265(4)
0.4772(3)
0.1924(3)
0.2216(3)
0.1494(4)
0.0474(4)
0.0151(4)
0.0877(3)
0.2119(3)
0.2820(3)
0.2260(4)
0.0970(4)
0.0240(3)
0.0802(3)
0.2656(3)
0.3020(4)
0.2769(5)
0.2141(4)
0.1814(4)
0.2069(3)
0.56520(3)
0.64797(3)
0.62646(8)
0.69493(8)
0.66886(9)
0.58429(8)
0.62720(9)
0.6359(1)
0.6161(1)
0.6364(1)
0.6698(1)
0.6956(1)
0.72121(1)
0.7479(1)
0.7505(1)
0.7250(2)
0.6974(1)
0.5431(1)
0.5124(1)
0.4983(1)
0.5151(1)
0.5450(1)
0.5588(1)
0.5165(1)
0.4843(1)
0.4486(1)
0.4446(1)
0.4753(1)
0.5116(1)
0.6072(1)
0.6522(1)
0.6857(1)
0.6757(2)
0.6314(2)
0.5970(1)
0.6245(1)
0.5815(1)
0.5630(1)
0.5880(2)
0.6301(1)
0.6480(1)
0.6294(1)
0.6046(1)
0.5906(1)
0.6013(1)
0.6247(1)
0.6387(1)
0.7094(1)
0.7307(1)
0.7774(2)
0.8023(2)
0.7814(1)
0.7352(1)
0.79271(8)
0.79891(7)
1.1459(2)
1.0253(2)
1.1147(2)
0.9203(2)
0.8364(2)
1.0840(3)
0.9698(3)
0.9362(3)
1.0256(3)
1.2176(3)
1.2521(3)
1.3512(3)
1.4154(3)
1.3805(3)
1.2829(3)
0.7654(3)
0.8429(3)
0.8300(4)
0.7404(4)
0.6607(4)
0.6728(3)
0.7691(3)
0.6815(3)
0.6673(4)
0.7402(4)
0.8282(4)
0.8431(3)
0.6783(3)
0.6994(3)
0.6173(4)
0.5110(4)
0.4877(3)
0.5699(3)
0.6552(3)
0.6273(3)
0.5178(3)
0.4363(3)
0.4649(3)
0.5736(3)
0.8890(3)
0.9892(3)
1.0609(3)
1.0322(3)
0.9324(4)
0.8591(3)
0.7795(3)
0.6996(3)
0.6738(4)
0.7267(4)
0.8071(4)
0.8355(3)
3.62(2)
3.45(2)
5.05(7)
4.51(6)
3.94(7)
2.92(6)
3.67(7)
3.53(9)
3.10(8)
3.09(8)
3.45(9)
3.44(8)
4.09(9)
5.2(1)
6.0(1)
6.6(1)
5.1(1)
3.65(9)
4.7(1)
5.6(1)
5.7(1)
5.9(1)
5.4(1)
3.80(9)
5.2(1)
6.5(1)
6.2(1)
5.5(1)
4.7(1)
3.74(9)
5.1(1)
5.9(1)
6.0(1)
6.0(1)
4.9(1)
3.66(9)
5.0(1)
6.0(1)
6.1(1)
6.1(1)
5.3(1)
3.37(8)
4.14(9)
5.2(1)
5.1(1)
4.9(1)
4.21(9)
3.43(8)
5.6(1)
7.0(1)
6.9(1)
5.5(1)
4.19(9)

N-phenylmaleimide derivatives
61
Table 4. Atomic Coordinates and Beq for Compound 2b
Atom
x
y
z
B
eq
P(1)
P(2)
O(1)
O(2)
O(3)
O(4)
N(1)
N(2)
N(3)
N(4)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
0.31822(5)
0.25581(6)
0.2120(1)
0.1165(1)
0.1727(4)
0.1854(6)
0.1584(2)
0.2595(2)
0.1848(2)
0.1557(6)
0.1981(2)
0.2187(2)
0.1888(2)
0.1487(2)
0.1369(2)
0.2049(2)
0.1844(2)
0.0959(2)
0.0301(2)
0.0486(2)
0.4140(2)
0.4407(2)
0.5190(3)
0.5707(3)
0.5446(3)
0.4667(2)
0.2333(2)
0.2686(2)
0.2020(2)
0.0985(2)
0.0620(2)
0.1289(2)
0.3955(2)
0.5625(2)
0.3994(3)
0.5089(3)
0.3432(2)
0.5067(2)
0.3995(2)
0.4531(2)
0.5612(2)
0.6161(2)
0.5651(2)
0.4567(2)
0.2301(2)
0.1304(3)
0.1056(3)
0.1798(4)
0.2790(3)
0.3040(2)
0.2245(2)
0.2242(2)
0.2096(3)
0.1959(3)
0.1928(3)
0.2073(2)
0.0470(3)
0.62492(5)
0.96640(5)
0.5579(1)
0.8340(1)
0.1153(3)
0.1404(5)
0.6826(1)
0.7080(1)
0.8960(1)
0.1010(4)
0.6425(2)
0.7217(2)
0.8043(2)
0.7798(2)
0.6324(2)
0.5778(2)
0.5274(2)
0.5327(2)
0.5874(2)
0.6378(2)
0.5957(2)
0.5040(2)
0.4894(2)
0.5648(3)
0.6555(2)
0.6715(2)
0.5057(2)
0.4480(2)
0.3594(2)
0.3259(2)
0.3822(2)
0.4709(2)
0.6783(2)
0.7453(2)
0.7421(2)
0.7646(2)
0.7000(2)
0.7006(2)
0.9938(2)
0.9222(2)
0.9387(2)
1.0258(2)
1.0980(2)
1.0824(2)
0.9262(2)
0.8664(2)
0.8383(3)
0.8697(3)
0.9311(3)
0.9592(2)
1.0872(2)
1.1489(2)
1.2457(3)
1.2832(3)
1.2223(3)
1.1264(2)
0.0285(3)
0.12992(6)
0.23340(6)
0.3222(1)
0.4987(2)
0.8299(4)
0.6615(6)
0.4392(2)
0.1732(2)
0.2991(2)
0.7268(5)
0.3428(2)
0.2729(2)
0.3232(2)
0.4298(2)
0.5320(2)
0.5763(2)
0.6648(3)
0.7112(2)
0.6684(2)
0.5781(2)
0.2404(2)
0.2291(3)
0.3150(3)
0.4123(3)
0.4247(3)
0.3403(3)
0.0392(2)
Ϫ0.0480(2)
Ϫ0.1193(3)
Ϫ0.1079(3)
Ϫ0.0237(3)
0.0495(2)
0.0314(2)
Ϫ0.0193(3)
Ϫ0.1452(3)
Ϫ0.1180(3)
Ϫ0.0687(3)
0.0566(2)
0.2879(2)
0.2553(3)
0.3028(3)
0.3827(3)
0.4153(3)
0.3678(2)
0.0745(2)
0.0149(3)
Ϫ0.1065(3)
Ϫ0.1694(3)
Ϫ0.1123(3)
0.0099(3)
0.2601(3)
0.1788(3)
0.2078(4)
0.3178(4)
0.3984(3)
0.3698(3)
0.6727(4)
3.49(2)
3.61(2)
4.32(5)
4.85(5)
18.5(2)
22.3(3)
3.76(5)
3.51(5)
3.73(5)
12.6(2)
3.42(6)
3.11(6)
3.11(6)
3.43(6)
3.41(6)
4.84(8)
6.1(1)
C(7)
C(8)
C(9)
5.39(9)
4.71(8)
4.25(7)
3.72(6)
5.20(8)
7.0(1)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(47)
7.6(1)
6.9(1)
5.20(8)
3.53(6)
4.36(7)
5.45(8)
5.70(9)
5.35(8)
4.52(7)
3.49(6)
5.87(9)
5.88(9)
5.59(9)
5.26(8)
4.75(8)
3.40(6)
4.88(8)
5.86(9)
5.44(9)
5.73(9)
5.16(8)
4.38(7)
6.16(9)
8.5(1)
8.3(1)
7.4(1)
5.62(9)
4.15(7)
5.71(9)
7.7(1)
7.9(1)
7.1(1)
5.60(9)
11.4(2)

6
2
Bodige, M e´ ndez-Rojas, and Watson
Table 5. Atomic Coordinates and Beq for Compound 3
Atom
x
y
z
B
eq
S(1)
S(2)
0.28506(2)
0.28665(3)
0.35836(6)
0.35959(7)
0.36841(7)
0.34963(9)
0.31651(8)
0.31661(9)
0.35028(9)
0.40266(9)
0.4184(1)
0.4506(1)
0.4674(1)
0.4516(1)
0.4182(1)
0.0064(2)
0.4975(2)
Ϫ0.0844(5)
0.5775(5)
0.2456(6)
0.0798(7)
0.1549(6)
0.3456(7)
0.4129(7)
0.2400(8)
0.0571(8)
0.0544(9)
0.229(1)
0.2804(1)
0.5249(1)
0.3098(3)
0.6147(3)
0.4700(3)
0.3788(4)
0.3833(4)
0.4737(4)
0.5313(4)
0.4980(4)
0.5811(5)
0.6043(6)
0.5482(6)
0.4681(6)
0.4382(5)
4.43(3)
4.59(3)
4.48(8)
4.65(7)
3.17(7)
3.4(1)
3.19(9)
3.35(9)
3.26(9)
3.7(1)
O(1)
O(2)
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
5.0(1)
6.1(1)
6.4(2)
6.4(2)
0.4126(9)
0.4199(8)
5.3(1)
Table 6. Atomic Coordinates and Biso/Beq for Compound 4
Atom
x
y
z
B
eq
S(1)
S(2)
O(1)
O(2)
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
Ϫ0.00088(6)
0.11646(5)
Ϫ0.0911(1)
0.0537(1)
Ϫ0.0271(2)
Ϫ0.0430(2)
0.0098(2)
0.0527(2)
0.0298(2)
Ϫ0.0625(2)
Ϫ0.0753(2)
Ϫ0.1077(2)
Ϫ0.1267(2)
Ϫ0.1140(2)
Ϫ0.0818(2)
0.0815(2)
0.0880(2)
0.1504(3)
0.2063(2)
0.2001(2)
0.1372(2)
0.1784(2)
0.2102(2)
0.2617(3)
0.2812(2)
0.2487(2)
0.1984(2)
Ϫ0.0876(1)
0.1141(1)
0.1231(3)
0.3882(3)
0.2867(3)
0.1586(4)
0.0779(3)
0.1534(4)
0.2913(4)
0.3957(4)
0.4062(4)
0.5133(5)
0.6113(5)
0.5999(5)
0.4926(5)
Ϫ0.1519(4)
Ϫ0.2652(4)
Ϫ0.3258(5)
Ϫ0.2707(5)
Ϫ0.1584(5)
Ϫ0.1006(4)
0.2361(4)
0.2826(5)
0.3708(5)
0.4149(5)
0.3682(5)
0.2753(4)
0.37495(7)
0.29046(6)
0.4169(1)
0.3237(1)
0.3786(2)
0.3909(2)
0.3653(2)
0.3389(2)
0.3435(2)
0.3992(2)
0.4686(2)
0.4897(2)
0.4402(3)
0.3687(3)
0.3486(2)
0.3775(2)
0.3409(2)
0.3473(3)
0.3912(3)
0.4277(2)
0.4243(2)
0.3151(2)
0.2620(2)
0.2792(3)
0.3495(4)
0.4034(3)
0.3873(2)
5.54(4)
3.76(3)
4.65(8)
3.78(7)
3.33(9)
3.2(1)
3.0(1)
2.8(1)
2.9(1)
3.3(1)
4.0(1)
5.1(1)
5.9(1)
6.4(2)
4.8(1)
4.0(1)
5.2(1)
6.1(2)
6.0(2)
5.1(1)
4.6(1)
3.3(1)
4.9(1)
7.3(2)
7.6(2)
6.1(2)
4.2(1)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)

N-phenylmaleimide derivatives
63
˚
Table 7. Interatomic Distances (A)
1
2a
2b
3
4
C(1)UN(1)
C(1)UC(2)
C(1)UO(1)
C(2)UC(3)
C(2)UN(2)
C(2)US(1)
C(3)UC(4)
C(3)UCl(1)
C(3)UN(3)
C(3)US(2)
C(4)UN(1)
C(4)UO(2)
N(1)UC(5)
C(5)UC(6)
C(5)UC(10)
C(6)UC(7)
C(7)UC(8)
C(8)UC(9)
C(9)UC(10)
N(2)UP(1)
N(3)UP(2)
P(1)UC(11)
S(1)UC(11)
P(1)UC(17)
P(1)UC(23)
P(2)UC(29)
S(2)UC(17)
P(2)UC(35)
P(2)UC(41)
1.385(6)
1.540(6)
1.202(6)
1.336(7)
1.315(6)
—
1.425(7)
1.739(5)
—
1.415(5)
1.474(6)
1.208(5)
1.383(6)
1.366(5)
—
1.468(6)
—
1.376(5)
—
1.406(5)
1.211(5)
1.413(5)
1.375(6)
1.370(6)
1.376(7)
1.359(7)
1.374(7)
1.375(7)
1.565(4)
1.586(4)
1.818(5)
—
1.830(5)
1.808(5)
1.813(5)
—
1.803(5)
1.799(5)
1.412(5)
1.480(5)
1.212(4)
1.362(5)
1.374(4)
—
1.504(5)
—
1.352(4)
—
1.394(5)
1.206(4)
1.423(5)
1.379(5)
1.377(5)
1.377(5)
1.379(6)
1.353(6)
1.390(5)
1.583(3)
1.586(3)
1.803(4)
—
1.808(4)
1.813(4)
1.814(4)
—
1.805(4)
1.794(4)
1.387(8)
1.492(9)
1.196(7)
1.327(8)
—
1.700(6)
1.494(9)
—
1.394(7)
1.494(8)
1.213(6)
1.322(7)
—
1.743(6)
1.509(8)
—
—
—
—
1.668(7)
1.387(8)
1.200(7)
1.450(7)
1.372(9)
1.368(9)
1.36(1)
1.36(1)
1.36(1)
1.41(1)
—
—
—
—
—
—
—
—
—
1.742(6)
1.416(7)
1.200(7)
1.424(7)
1.370(7)
1.387(8)
1.381(8)
1.380(9)
1.409(9)
1.373(9)
—
—
—
1.774(7)
—
—
1.431(6)
1.214(6)
1.429(7)
1.398(7)
1.383(7)
1.370(7)
1.370(8)
1.376(8)
1.366(7)
1.604(4)
—
1.808(5)
—
1.792(5)
1.826(5)
—
—
1.775(6)
—
—
—
—
—
—
3
phenyl groups); Ep
c
ϭ 1.34 V; UV-Visible spectrum
␧
max ϭ 3.3 ϫ 10 ; ␭max ϭ 490 nm (broad), ␧max
ϭ
3
3
(
acetone): ␭max ϭ 398 nm, ␧max ϭ 6.9 ϫ 10 ; Excitation
4.3 ϫ 10 . When excited at 268 nm, a very weak
emission with a maximum at 602 nm is observed.
When excited at 490 nm a strong emission centered
at 628 nm is observed. The sample is bright red under
UV light. Recrystallization from nitromethane yields
crystals containing a molecule of nitromethane, 2b.
In nitromethane the absorption spectra shows only
one absorption maxima (␭ ϭ 403), and the emission
is quenched.
at 398 nm in CH Cl gave a sharp emission maximum
3
at 538 nm, while monitoring at 538 nm gave an excita-
tion maximum at 338 nm. The sample is bright yellow
under UV light.
N-phenyl-di(triphenylphosphoranamino)maleimide
(
2)
To a solution of 2,3-dichloro-N-phenylmalei-
mide (1.21 g, 5 mmol) in 20 mL of methanol and
.65 g (10 mmol) of sodium azide (stirred for 1 h)
N-phenyl-2,3-dithiomaleimide (3)
0
triphenylphosphine (2.64 g, 10 mmol) was added
slowly and stirred for 2 h. The yellow solution gradu-
ally turned red. After the solvent was removed, the
To a solution of 1.1 g (10 mmol) of benzylmer-
captan in 100 mL of ethanol was added 1.17 g (4
mmol) of 2,3-dichloro-N-phenylmaleimide. The mix-
ture was refluxed 3 h and cooled to 0ЊC. The solid
was filtered and recrystallized from nitromethane,
red solid was washed with water and dried giving
1
2
.19 g of 2a (yield, 70%), m.p. 212–214ЊC. H NMR:
1
ͳ, 7.263–7.619 (35 H, multiplets consistent with seven
phenyl groups); Ep ϭ ϩ0.31, ϩ0.71, ϩ1.12 and ϩ1.37
V; UV-Visible spectrum (CHCl
yield (40%) m.p. 205–206ЊC. H-NMR: ͳ, 7.513–7.259
Ϫ1
c
(multiplet). IR(cm ): 3059, 1796, 1732, 1721, 1576,
3
): ␭max ϭ 268 nm,
1634, 1505; Ep
c
ϭ ϩ.80 and ϩ1.03 V; UV (CHCl ) :
3

6
4
Bodige, M e´ ndez-Rojas, and Watson
Table 8. Selected Valence Angles (Degrees) for Compounds 1, 2a, 2b, 3, and 4
1
2a
2b
3
4
N(1)UC(1)UC(2)
N(1)UC(1)UO(1)
O(1)UC(1)UC(2)
C(1)UC(2)UC(3)
C(1)UC(2)UN(2)
C(3)UC(2)UN(2)
C(1)UC(2)US(1)
C(3)UC(2)US(1)
C(2)UC(3)UC(4)
C(2)UC(3)UCl(1)
C(4)UC(3)UCl(1)
C(2)UC(3)UN(3)
C(4)UC(3)UN(3)
C(2)UC(3)US(2)
C(4)UC(3)US(2)
C(3)UC(4)UN(1)
C(3)UC(4)UO(2)
N(1)UC(4)UO(2)
C(1)UN(1)UC(4)
C(1)UN(1)UC(5)
C(4)UN(1)UC(5)
N(1)UC(5)UC(6)
N(1)UC(5)UC(10)
C(6)UC(5)UC(10)
C(5)UC(6)UC(7)
C(6)UC(7)UC(8)
C(7)UC(8)UC(9)
C(8)UC(9)UC(10)
C(5)UC(10)UC(9)
C(2)UN(2)UP(1)
C(2)US(1)UC(11)
C(3)UN(3)UP(2)
C(3)US(2)UC(17)
N(2)UP(1)UC(11)
N(2)UP(1)UC(17)
N(2)UP(1)UC(23)
N(3)UP(2)UC(29)
N(3)UP(2)UC(35)
N(3)UP(2)UC(41)
107.5(4)
127.0(5)
125.5(5)
103.8(4)
123.9(5)
133.2(5)
—
108.6(4)
123.2(5)
128.2(5)
106.7(4)
119.2(4)
134.1(4)
—
—
108.9(4)
—
107.7(2)
125.3(2)
127.0(2)
108.6(2)
122.9(2)
128.5(2)
—
—
107.1(2)
—
104.8(6)
127.0(7)
128.1(6)
109.9(6)
—
106.5(5)
125.3(6)
128.2(7)
109.5(6)
—
—
—
121.4(5)
128.7(6)
107.8(6)
—
—
—
114.2(5)
136.2(5)
108.3(5)
—
—
—
—
114.1(4)
126.2(4)
119.7(4)
—
—
—
—
—
126.7(4)
124.3(4)
—
136.3(2)
116.5(2)
—
—
—
130.3(6)
121.9(5)
106.0(6)
126.8(7)
127.2(7)
111.4(6)
123.6(6)
125.0(6)
119.9(7)
117.9(7)
122.2(7)
118.9(8)
121.7(9)
119.1(9)
121.0(8)
117.1(8)
—
—
—
—
—
—
—
—
—
130.0(5)
120.7(5)
105.9(5)
129.4(6)
124.7(6)
109.6(5)
124.9(5)
125.6(6)
120.4(6)
118.8(6)
120.8(6)
120.8(6)
119.3(6)
119.9(7)
120.1(7)
119.2(6)
—
104.0(3)
—
104.1(3)
—
—
—
—
—
—
—
—
—
105.6(4)
132.2(5)
122.1(5)
109.0(4)
124.0(4)
126.9(4)
119.5(5)
121.5(5)
119.1(5)
129.9(6)
120.4(6)
119.8(5)
120.6(6)
120.1(5)
128.2(4)
—
107.7(4)
128.0(5)
124.2(5)
108.0(4)
127.0(4)
124.9(4)
120.4(5)
120.7(5)
118.9(5)
120.9(5)
120.5(5)
118.5(5)
121.6(5)
119.6(5)
129.1(3)
—
108.0(2)
127.4(2)
124.6(3)
108.5(2)
124.7(2)
126.7(2)
119.9(2)
120.6(2)
119.5(3)
120.7(3)
119.9(2)
119.2(3)
121.8(3)
118.9(3)
128.8(2)
—
—
—
112.5(3)
106.1(2)
116.6(3)
—
127.8(3)
—
130.7(2)
—
106.9(2)
114.0(2)
116.3(2)
105.3(2)
114.0(2)
119.6(2)
117.3(1)
116.3(1)
105.2(1)
115.8(1)
116.3(1)
106.2(2)
—
—
—
2
␭
max ϭ 320 nm, ␧max ϭ 1.6 ϫ 10 . Excitation at 350
was filtered and recrystallized from nitromethane,
1
nm gave emission maxima at 537 nm and 632 nm.
Monitoring at 537 nm gave excitation maxima at 292
and 400 nm, while monitoring at 632 nm gave excita-
tion maxima at 292 and 367 nm.
yield (70%) m.p. 111–113ЊC. H-NMR: ͳ, 7.387–7.256
Ϫ1
(multiplets). IR(cm ): 3050, 1775, 1709, 1663, 1576,
1520, 1503, 1474, 1443, 1385, 1198; Ep ϭ ϩ1.64 and
c
ϩ1.86 V; Ep
a
ϭ Ϫ0.18 and ϩ0.44 V; UV (CHCl
3
):
3
␭max ϭ 321 nm, ␧max ϭ 3.3 ϫ 10 ; ␭max ϭ 426 nm,
3
␧max ϭ 3.8 ϫ 10 . Excitation at 398 resulted in a very
N-phenyl-2,3-di(thiophenyl)maleimide (4)
weak emission at 610 nm.
To a solution of 1.1 g (10 mmol) of thiophenol
in 100 mL of ethanol was added 1.17 g (5 mmol)
of 2,3-dichloro-N-phenylmaleimide. The mixture was
refluxed 1 h and cooled to 0ЊC. The orange-red solid
Discussion
All phenyl rings and five-membered maleimide
rings are planar. The N-phenyl ring and the malei-

N-phenylmaleimide derivatives
65
Fig. 1. Thermal ellipsoid drawing of compound 1. Ellipsoids are
drawn at the 35% probability level.
Fig. 3. Packing diagram of compound 2 in structure 2b.
mide ring exhibit interplanar angles of 40.1(4)–
4
9.7(4)Њ for compounds 1, 2a, 2b, and 4, while the
corresponding angle in compound 3 is 63.1(2)Њ. The
equivalent bonds in the five-membered ring of 1 are
significantly different due to the non-symmetric sub-
stitution pattern difference C(1)UC(2) and
C(3)UC(4) differ by 19␴, while N(1)UC(1) and
N(1)UC(4) differ by 7␴. These distances are equiva-
lent in 2a but are statistically different in 2b (5␴ and
4
␴, respectively), which may result from molecule–
solvent interactions. The C(2)UN(2) bond in 1 is
significantly shorter than the corresponding distance
˚
in 2a and 2b (1.315(6), 1.366(5), and 1.374(4) A, re-
spectively), which reflects differences in steric hin-
drance and electronic effects.
AM1 and Gaussian 3-21G* calculations indicate
the HOMOs in 2,3-dichloro-N-phenylmaleimide and
in 1 and 2 are primarily phenyl and N,O based, while
Fig. 2. Thermal ellipsoid drawing of compound 2 in structure
Fig. 4. Thermal ellipsoid drawing of compound 3. Ellipsoids are
drawn at the 35% probability level.
2
a. Ellipsoids are drawn at the 35% probability level.

6
6
Bodige, M e´ ndez-Rojas, and Watson
Acknowledgments
We thank the Robert A. Welch Foundation
Grant P-0074) and the TCU Research Fund for their
(
financial support, and John St. John for the emission
spectroscopy measurements.
References
1
2
.
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Sun, D.; Watson, W.H. J. Org. Chem. 1997, 62, 4082.
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3.
B o¨ hm, E.; Dehnicke, K.; Beck, J.; Hiller, W.; Str a¨ hler, J.;
Maurer, A.; Fenske, D.Z. Z. Naturforsch. 1988, 43b,
1
38.
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Moser, H.; Pissiotas, G.; Brunner, H.G. US Pat. 4,929,272.
May 29, 1990.
Haugland, R.P.; Whitaker, J.E. US Pat. 5,227,487. July 1993;
US Pat. 5,442,045 Aug. 15 1995.
Fig. 5. Thermal ellipsoid drawing of compound 4. Ellipsoids are
drawn at the 35% probability level.
6
7
.
.
Kagaku, Y.; Kagyo, K.K. JP 57,144,203. Sept. 1982.
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(a) Relles, H.M. J. Org. Chem. 1972, 37, 360. (b) Relles, H.M.;
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8
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the LUMO is concentrated on the OuCUCuCU
CuO moiety in the 2,3-dichloro compound, but ex-
clusively in the phenyl groups of the triphenylphos-
phines in 1 and 2. Compounds 1, 2a, and 3 fluoresce
strongly while 2b, 4, and 2,3-dichloro-N-phenylmalei-
mide do not. The nitromethane solvate molecule ef-
fectively quenches the fluorescence of 2. At present,
we are investigating energy transfer between two dif-
ferently substituted maleimides connected via the
N-substituents.
9
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10. Sheldrick, G.M. SHELXS86. Program for the Solution of
Crystal Structures; University of G o¨ ttingen: Germany,
1
986.
1
1
1
1. teXsan for Windows: Crystal Structure Analysis Package; Mo-
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