Di- and triindolylmethanes: Molecular structures and spectroscopic characterization of potentially bidentate and tridentate ligands

Article abstract of DOI:10.1023/A:1024234618248

4-Bromophenyldi(3-methylindol-2-yl)methane (2) and 2-methoxyphenyldi(3- methylindol-2-yl)methane (3) were prepared by sulfuric-acid-catalyzed reactions of 3-methylindole with 4-bromobenzaldehyde and o-anisaldehyde, respectively. Di(3-methylindol-2-yl)phenylmethane (1) and tri(3-methylindol-2-yl)methane (4) were similarly prepared as described previously. Spectroscopic data ( ¹H, ¹³C NMR) and the X-ray crystal structures for 1·C₂H₅OH and 2-4 are reported. The molecular structure of 1·C₂H₅OH shows hydrogen bonding of both indolyl NH protons to the oxygen of an ethanol molecule. Crystal data for 1·C₂H₅OH: Orthorhombic, Pca2₁, a = 23.9782(17) A, b = 8.4437(7) A, c =11.3029(9) A, V = 2288.4(3) A³, R₁ = 0.0597. Crystal data for 2: Orthorhombic, P2₁2₁2₁, a = 8.911(3) A, b = 9.584(4) A, c = 24.040(11) A, V = 2053.0(14) A³, R ₁ = 0.0454. Crystal data for 3: Monoclinic, P2₁/c, a = 9.737(2) A, b = 25.035(6) A, c = 9.359(2) A, β= 114.853(4)°, V = 2070.2(8) A³, R₁ = 0.0511. Crystal data for 4: Trigonal, R3, a = 14.2214(10) A, c = 9.6190(10) A, V = 1684.8(2) A³, R₁ = 0.0425.

Full text of DOI:10.1023/A:1024234618248

C
Journal of Chemical Crystallography, Vol. 33, No. 7, July 2003 ( 2003)
Di- and triindolylmethanes: molecular structures
and spectroscopic characterization of potentially
bidentate and tridentate ligands
Mark R. Mason,(1) Thomas S. Barnard,(1) Mawuto F. Segla,(1)
Baohan Xie,(1) and Kristin Kirschbaum(1)
Received August 20, 2002
4-Bromophenyldi(3-methylindol-2-yl)methane (2) and 2-methoxyphenyldi(3-methylindol-
2-yl)methane (3) were prepared by sulfuric-acid-catalyzed reactions of 3-methylindole
with 4-bromobenzaldehyde and o-anisaldehyde, respectively. Di(3-methylindol-2-
yl)phenylmethane (1) and tri(3-methylindol-2-yl)methane (4) were similarly prepared as
described previously. Spectroscopic data (1H, 13C NMR) and the X-ray crystal struc-
tures for 1 C2H5OH and 2–4 are reported. The molecular structure of 1 C2H5OH
shows hydrogen bonding of both indolyl NH protons to the oxygen of an ethanol
˚
molecule. Crystal data for 1 C2H5OH: Orthorhombic, Pca21, a = 23.9782(17) A, b =
3
˚
˚
˚
8.4437(7) A, c = 11.3029(9) A, V = 2288.4(3) A , R1 = 0.0597. Crystal data for
˚
˚
˚
2: Orthorhombic, P212121, a = 8.911(3) A, b = 9.584(4) A, c = 24.040(11) A, V =
3
˚
˚
2053.0(14) A , R1 = 0.0454. Crystal data for 3: Monoclinic, P21/c, a = 9.737(2) A,
3
˚
˚
˚
b = 25.035(6) A, c = 9.359(2) A, = 114.853(4) , V = 2070.2(8) A , R1 = 0.0511.
3
˚
˚
˚
Crystal data for 4: Trigonal, R3, a = 14.2214(10) A, c = 9.6190(10) A, V = 1684.8(2) A ,
R1 = 0.0425.
KEY WORDS: Diindolylmethanes; triindolylmethanes; nitrogen-donor ligands; hydrogen bonding.
--- ---
Introduction
Pyrrolyl,1–3 indolyl,4,5 and carbazolyl6 lig-
for -coordination and M N M bridging, and
minimal N→M -donation. These attributes may
prove ideal for increasing the electrophilic char-
acter of main group and transition elements.
In this regard, there are numerous diindolyl-
methanes reported in the literature7 that could
potentially serve as bidentate or, for those with
an additional ligating substituent, tridentate lig-
ands for transition and main group elements.
Surprisingly, diindolylmethanes had not been in-
vestigated as ligands until our recent demon-
strations of the bidentate coordination of 1–3
to group 4 (Ti, Zr, Hf),8 group 13 (Al),9 and
group 14 (Si)10 elements. The resulting aluminum
ands have recently been recognized to provide sig-
nificantly different electronic and steric properties
to complexes of main group and transition met-
als than those offered by more common amido,
pyrazolyl, and imidazole ligands. These differ-
ences include strong electron-withdrawing ability
1---
when bound in an
N mode, reduced tendency
(1) Department of Chemistry, University of Toledo, Toledo, Ohio
43606-3390.
To whom correspondence should be addressed. E-mail:
mmason5@uoft02.utoledo.edu
531
C
1074-1542/03/0700-0531/0 2003 Plenum Publishing Corporation

532
Mason, Barnard, Segla, Xie, and Kirschbaum
Scheme 3.
inorganic and organometallic chemistry. We here
clarify some aspects of the spectroscopic and
structural characterization of 1 and 4 that are not
currently available in the literature. In addition,
we report the synthesis and spectroscopic and
structural characterization of compounds 2 and 3.
Scheme 1.
complexes are effective catalysts for the polymer-
ization of epichlorohydrin, whereas the group 4
complexes show activity for the polymerization
of ethylene. It is also noteworthy that the molecu-
lar structures of these complexes are reminiscent
of those for the ubiquitous “scorpionate” and “het-
eroscorpionate” bis(pyrazolyl)borate ligands.11
Similarly, triindolylmethanes12 such as 4 of-
fer alternative steric and electronic properties to
those offered by the traditional triamidoamine
(5),13,14 triamido (6),15 and tris(pyrazolyl)borate
ligands (7).11 We previously demonstrated4,5 that
tri(3-methylindol-2-yl)methane (4) is an effec-
tive framework for the construction of the very
bulky and -acidic phosphine 8a and deriva-
tives 8b–f. The -acidity of 8a is attributable
Experimental
Di(3-methylindol-2-yl)phenylmethane (1)16
and tri(3-methylindol-2-yl)methane (4)17 were
prepared from sulfuric-acid-catalyzed reac-
tions of 3-methylindole with benzaldehyde
and triethylorthoformate, respectively, as de-
scribed in the literature. New compounds, 4-
bromophenyldi(3-methylindol-2-yl)methane (2)
and
2-methoxyphenyldi(3-methylindol-2-yl)
methane (3), were similarly prepared as described
below. Reagents were purchased from Aldrich
Chemical Co. and used as received. Solvents were
purified by standard methods. NMR spectra were
obtained on a Varian VXRS400 by spectrometer
by using a deuterated solvent as the internal lock.
Chemical shifts are reported relative to tetram-
ethylsilane. Elemental analyses were performed
by Schwarzkopf Microanalytical Laboratories,
Woodside, NY.
--- ---
to constraint of the N P N angle by, and the
poor -donating ability of, the tri(3-methylindol-
2-yl)methane framework.
The unique ligating properties of
poly(indolyl)methanes and the structural analo-
gies of 4 to the tripodal ligands 5–7, and of 1–3
to the bis(pyrazolyl)borates, suggest a promising
future for poly(indolyl)methanes as ligands in
Synthesis of 4-bromophenyldi (3-methylindol-
2-yl)methane (2)
4-Bromobenzaldehyde (3.70 g, 20.0 mmol)
was added to a stirred solution of 3-methylindole
(5.21 g, 39.7 mmol) in 20 mL of ethanol.
Concentrated sulfuric acid (10 drops) was added
and the reaction solution stirred for 24 h at room
temperature. The resulting precipitate was iso-
lated by filtration and washed with cold ethanol
Scheme 2.

Di- and triindolylmethanes
533
program.20 The structures were solved by direct
methods using SHELXS-8621 and refined by least-
squares methods on F2, using SHELXL-93.22 Sys-
tematic absences for 1 C2H5OH were consistent
with the space group Pca21 and Pbcm. The ini-
tial choice of Pca21 was based on the low value
(0.760) of |E2-1| and was confirmed by the pack-
ing and the absence of an additional symmetry
element within the molecules. The space groups
of 2 and 3 were uniquely defined by the systematic
absences to be P212121 and P21/c, respectively.
The space group ambiguity for 4 (R3 vs. R-3) was
resolved in favor of R3 by consideration of the
point symmetry of the molecule and a density cal-
culation that resulted in Z = 3. All non-hydrogen
atoms were refined with anisotropic displacement
parameters. Hydrogen atoms in 1 C2H5OH, 3,
and 4 were located and refined with isotropic
displacement parameters. The hydrogen atoms
in 2 were placed in calculated positions and in-
cluded in the refinement. Details of data collec-
tion and refinement are provided in Tables 1 and
2. Selected distances and angles are provided in
Tables 5–8. Atomic coordinates and equivalent
isotropic displacement parameters are provided in
Tables 9–12.
(4 10 mL). Recrystallization from hot ethanol
afforded colorless crystals of 2. Yield: 8.00 g,
93%. Anal. Calcd for C25H21BrN2: C, 69.94; H,
4.93; N, 6.52. Found: C, 69.54; H, 4.86; N, 6.45.
Synthesis of 2-methoxyphenyldi (3-methylindol-
2-yl)methane (3)
o-Anisaldehyde (1.90 mL, 16.0 mmol) was
added via syringe to a stirred solution of 3-
methylindole (4.20 g, 32.0 mmol) in 30 mL of
ethanol. Concentrated sulfuric acid (10 drops) was
added and the reaction solution stirred for 24 h at
room temperature. The resulting precipitate was
isolated by filtration and washed with cold ethanol
(4 10 mL). The crude product was recrystal-
lized from hot chloroform upon cooling to 25 C
overnight. The product was isolated by filtration,
washed with cold ethanol (3 10 mL), and dried
in vacuo. Yield: 4.86 g, 80%. Anal. Calcd for
C26H24N2O: C, 82.07; H, 6.36; N, 7.36. Found:
C, 81.31; H, 6.28; N, 7.29.
X-ray crystallography for 1 C2H5OH and 2–4
Crystals were grown by slow evaporation
of solvent from concentrated solutions at room
temperature. The following solvents were uti-
lized in the crystallizations: compounds 1 and 3,
ethanol; compound 2, chloroform and n-heptane
(1:1); compound 4, methylene chloride and hex-
anes (1:3). Compound 1 crystallized as an ethanol
solvate. The X-ray diffraction data were collected
on a Siemens three-circle platform diffractome-
ter equipped with a 1K CCD detector. The frame
data were acquired with the SMART18 software
Results and discussion
It is well-established that acid-catalyzed re-
actions of an indole with an aldehyde or ketone
give diindolylmethanes.23 Indoles preferentially
react with electrophiles at C3, and so this pro-
cedure typically produces 3,30-diindolylmethanes
(Eq. 1). However, use of a C3-substituted indole
results in 2,2
0-diindolylmethanes that are more
˚
using Mo K radiation ( = 0.710 73 A). Cell
conducive to coordination, upon deprotonation,
to transition or main group elements to form six-
membered chelate rings.8–10 Representative exam-
ples of known 2,20-diindolylmethanes are illus-
trated in Eq. (2).
constants were determined with SAINT19from the
complete data sets. A complete hemisphere was
scanned on ω (0.3 ) with a run time of 30 s/frame.
A total of 1271 frames were collected for the
data set. An additional 50 frames, identical to
the first 50 frames, were collected to determine
crystal decay. The frames were integrated using
the SAINT19 software and the data were corrected
for absorption and decay by using the SADABS

534
Mason, Barnard, Segla, Xie, and Kirschbaum
Table 1. Crystal Data and Structure Refinement for 1 C2H5OH and 2
Compound
1 C2H5OH
191640
C27H28N2O
396.51
293(2)
Orthorhombic
Pca21
2
CCDC deposit no.
Chemical formula
Formula weight
Temperature, K
Crystal system
Space group
191641
C25H21BrN2
429.35
293(2)
Orthorhombic
P212121
˚
˚
˚
Unit cell dimensions
a = 23.9782(17) A
a = 8.911(3) A
˚
b = 8.4437(7) A
b = 9.584(4) A
˚
˚
c = 11.3029(9) A
c = 24.040(11) A
3
˚
Volume, A
2288.4(3)
2053.0(14)
Z
4
4
Density (calculated), Mg/m3
Absorption coefficient, mm
1.151
0.070
1.389
2.015
1
range for data collection, deg
Reflections measured
2.48–29.80
15674
2.44–29.66
22160
Independent/observed reflections
Data/restraints/parameters
Absolute structure parameter
Goodness of fit on F2
Final R indices [I > 2 (I)]a
R indices (all data)
5059 (Rint = 0.0824)
5437 (Rint = 0.0354)
3209/1/383
5437/0/248
2(2)
1.050
0.00(1)
1.044
R1 = 0.0597, wR2 = 0.1031
R1 = 0.0454, wR2 = 0.1011
R1 = 0.1147, wR2 = 0.1210
R1 = 0.0790, wR2 = 0.1177
a R1(F) = 6||Fo| |Fc||/6|Fo|. wR2(F2) = [6[w(Fo2 Fc2)2]/6[w(Fo2)2]]1/2
.
Table 2. Crystal Data and Structure Refinement for 3 and 4
Compound
3
4
CCDC deposit no.
Chemical formula
Formula weight
Temperature, K
Crystal system
Space group
191642
C26H24N2O
380.47
200(2) K
Monoclinic
P21/c
191643
C28H25N3
403.51
293(2)
Trigonal
R3
˚
˚
Unit cell dimensions
a = 9.737(2) A
a = 14.2214(10) A
˚
b = 25.035(6) A
˚
˚
c = 9.359(2) A
c = 9.6190(10) A
= 114.853(4)
2070.2(8)
4
3
˚
Volume, A
1684.8(2)
3
1.193
0.071
Z
Density (calculated), Mg/m3
Absorption coefficient, mm
1.221
0.075
1
range for data collection, deg
Reflections measured
2.44–29.80
14589
2.69–29.63
3977
Independent/observed reflections
Data/restraints/parameters
Absolute structure parameter
Goodness of fit on F2
Final R indices [I > 2 (I)]a
R indices (all data)
5248 (Rint = 0.0309)
1890 (Rint = 0.0290)
3775/0/358
1537/1/128
1(3)
1.009
1.038
R1 = 0.0511, wR2 = 0.1249
R1 = 0.0425, wR2 = 0.1019
R1 = 0.0764, wR2 = 0.1373
R1 = 0.0561, wR2 = 0.1086
P
a R1(F) = ||Fo| |Fc||/6|Fo|. wR2(F2) = [6[w(Fo2 Fc2)2]/6[w(Fo2)2]]1/2
.

Di- and triindolylmethanes
535
a singlet methine resonance in the range 6.23–
6.03 ppm, consistent with the methine resonances
observed by Pindur24 for 9a–9i (5.88–6.45 ppm)
in chloroform-d. Resonances for H7 and H4 of
1–4 are well-resolved doublets and those for H6
and H5 are well-resolved triplets in dmso-d6.
There is considerable overlap of resonances for
H4, H5, H6, and H7, when the NMR spectra of
1–4 are obtained in chloroform-d or benzene-
d6. We also note from our published and ongo-
ing work that the resonance for H7 is typically
shifted downfield upon complexation to a main
group or transition element, which increases res-
olution in this region of the spectrum, even in
chloroform-d.
In our hands, acid-catalyzed reactions of 3-
methylindole with benzaldehyde, o-anisaldehyde,
or 4-bromobenzaldehyde in methanol gave 2,20-
di(3-methylindolyl)methanes 1–3 as white solids
in yields of 72, 93, and 80%, respectively. The
preparation of 1 by this method was previously
reported by Dostal,16 and the preparation of
2 is comparable to the preparations of similar
compounds 9a and 9b as reported by Pindur.24
2,20,200-Tri(3-methylindolyl)methane 4 was simi-
larly prepared by reaction of 3-methylindole with
triethylorthoformate in methanol using the pro-
cedure previously reported by Dobeneck et al.
(Eq. 3).17
1
As expected, H NMR chemical shifts for
indole NH protons in 1–4 are shifted down-
field (10.49–10.34 ppm) in the polar solvent
dmso-d6, consistent with the chemical shifts re-
ported for 2,20-biindolyl (11.5 ppm),25 tris(2-
methyl-3-indolyl)methane (10.5 ppm),26 and 3-
methylindole (10.70 ppm) in the same solvent.
The NH resonances for 1–4 appear upfield in
chloroform-d at 7.56, 7.55, 7.68, and 7.73 ppm,
respectively. We find that compounds 1 and 3 give
1H NMR data obtained for 1–4 in dmso-
d6 are provided in Table 3. Compounds 1–4
each exhibit a single resonance for the 3-methyl
groups in the range 2.15–1.96 ppm, as well as
Table 3. 1H NMR Data for 1–4a
Resonance,
H6
Compound
NH
H7
H4
H5
CH
Me
OMe
3.75
Aryl
1
2
10.44
10.43
7.42 (d, 8.0)b
7.43 (d, 7.6)
7.14 (d, 8.0)
7.29 (d, 8.0)
7.01 (t, 7.2)
7.02 (t, 7.6)
6.95 (t, 7.2)
6.96 (t, 7.2)
6.03
6.03
2.15
2.13
7.34–7.23 (m)
7.53 (d, 8.4)
7.09 (d, 8.4)
7.20–6.90 (m)
3
4
10.34
10.49
10.70
7.38 (d, 7.6)
7.42 (d, 8.0)
7.44 (d, 7.6)
7.27 (d, 8.0)
7.30 (d, 8.0)
7.30 (d, 8.0)
6.98 (t, 7.6)
7.01 (t, 7.4)
7.04 (t, 7.2)
6.92 (t, 7.6)
6.94 (t, 7.4)
6.95 (t, 7.2)
6.22
6.23
1.96
2.07
2.23
3-Methylindole
aSpectra were obtained in dmso-d6. Chemical shifts are reported in ppm downfield of Me4Si.
bMultiplicity, 3
values (Hz) are given in parentheses.
J
HH

536
Mason, Barnard, Segla, Xie, and Kirschbaum
Table 4. 13C NMR Data for 1–4a
Resonance,
C4
Compound
C2
C3
C3a
C5
C6
C7
C7a
3-Me
CH
1
2
3
4
134.25
133.63
134.25
133.70
106.76
106.76
106.01
107.18
128.45
128.33
129.32
129.32
117.87
117.76
117.55
118.51
120.69
120.63
120.26
121.32
118.24
118.17
118.03
118.90
110.98
110.93
111.00
111.82
135.55
135.46
135.32
136.17
8.46
8.30
8.23
8.89
40.87b
40.41b
34.62
34.27
aSpectra were obtained in dmso-d6. Chemical shifts are reported in ppm downfield of Me4Si.
bObserved in CDCl3.
cAryl resonances and assignments for 1: 141.17 (i), 128.45 (o), 128.21 (m), 126.56 (p). 2: 140.42 (i), 131.19 (m), 130.39
(o), 119.63 (p). 3: 128.59 (i), 156.50 (o), 111.0 (m), 128.05 (p), 120.43 (m), 128.72 (o), 55.68 (Me).
sulfonium ylides.29 In addition, the 13C chem-
ical shift assignments are consistent with the
multiplicity of peaks and coupling constants ob-
served in proton-coupled 13C NMR spectra for 3
and 4.
X-ray crystallography confirmed the molec-
ular structures and atom connectivity for 1–
4 as illustrated in Figs. 1–5. For each struc-
ture, the indole rings are planar with bond
distances and angles (Tables 5–8) comparable
with those previously reported for other indole
derivatives.30 The most notable structural feature
is the hydrogen-bound ethanol solvate molecule
in 1 C2H5OH. The indole rings in 1 C2H5OH
are rotated slightly about the bridging methine
NH resonances at 7.10 and 7.34 ppm in benzene-
d6, and Pindur previously reported the NH reso-
nance of 4 at 9.62 ppm in acetone-d6.27 We also
note a strong downfield shift of the NH resonance
of 4 in the presence of nBu4NF (12.44 ppm) and
nBu4NI (8.29 ppm) in chloroform-d, indicative
of strong hydrogen bonding between NH protons
andthehalide. Sesslerhasinvestigatedanionbind-
ing by sapphyrins and dipyrromethanes,28 and it
appears from preliminary NMR studies that di-
and triindolylmethanes such as 1–4 may similarly
complex with anions. Further details on anion
binding by 1–4 and related compounds are cur-
rently under investigation.
1
13C{ H} NMR data for 1–4 are provided
in Table 4. Assignments are made by compar-
ison to assignments made by Park et al. for
3-methylindole, 2-methylindole, and indole 3-
Fig. 1. ORTEP drawing of 1. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for
clarity.
Fig. 2. ORTEP drawing of 1 C2H5OH showing hydrogen
bonding of NH protons to an ethanol molecule.

Di- and triindolylmethanes
537
Fig. 5. ORTEP drawing of 4. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for
clarity.
Fig. 3. ORTEP drawing of 2. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for
clarity.
˚
Table 5. Selected Distances (A) and Angles (deg) for 1 C2H5OH
carbon such that both indole NH protons are di-
rected toward the oxygen atom of the ethanol
molecule to accommodate hydrogen bonding.
Distance
---
---
C(12) C(19)
N(1) C(11)
1.392(4)
1.367(4)
2.930(4)
3.006(3)
1.507(4)
1.364(4)
1.442(4)
1.498(4)
1.394(4)
1.418(4)
1.389(4)
1.393(5)
1.392(4)
1.398(4)
---
N(1) C(18)
---
C(13) C(14)
---
---
---
The torsion angles N(1) C(11) C(1) C(2)
---
---
C(13) C(18)
N(1) O(30)
---
---
---
and N(2) C(21) C(1) C(2) in 1 C2H5OH are
54.5 and 50.5 , respectively, compared with
torsion angles of 39.4 and 78.0 for 2 and
---
---
N(2) O(30)
C(14) C(15)
---
---
C(1) C(11)
C(15) C(16)
---
---
C(11) C(12)
C(16) C(17)
---
---
C(17) C(18)
C(12) C(13)
Angles
---
---
---
---
C(11) N(1) C(18) 109.1(3)
C(28) N(2) O(30) 129.7(2)
---
---
--- ---
C(11) N(1) O(30) 121.95(18) C(2) C(1) C(11) 113.3(2)
--- --- --- ---
C(18) N(1) O(30) 128.59(19) C(2) C(1) C(21) 114.5(2)
--- --- --- ---
C(21) N(2) C(28) 109.1(2) C(11) C(1) C(21) 109.8(2)
--- --- --- ---
C(21) N(2) O(30) 119.48(18) N(1) O(30) N(2) 67.63(8)
˚
Table 6. Selected Distances (A) and Angles (deg) for 2
Distance
---
---
C(13) C(14)
N(1) C(11)
1.384(5)
1.370(5)
1.502(5)
1.367(5)
1.422(6)
1.489(6)
1.425(5)
1.389(6)
1.399(7)
1.366(8)
1.359(7)
1.397(6)
---
---
N(1) C(18)
C(13) C(18)
---
---
C(14) C(15)
C(1) C(11)
---
---
C(11) C(12)
---
C(15) C(16)
---
C(16) C(17)
C(12) C(13)
---
---
C(12) C(19)
C(17) C(18)
Angles
---
---
---
---
---
---
C(11) N(1) C(18)
109.9(3) C(2) C(1) C(21) 112.2 (3)
--- ---
C(21) N(2) C(28)
--- ---
109.4(3) C(11) C(1) C(21) 110.1(3)
114.2(3)
Fig. 4. ORTEP drawing of 3. Thermal ellipsoids are drawn
at the 50% probability level. Hydrogen atoms are omitted for
clarity.
C(2) C(1) C(11)

538
Mason, Barnard, Segla, Xie, and Kirschbaum
Table 9. Atomic Coordinates (104) and Equivalent Isotropic
˚
Table 7. Selected Distances (A) and Angles (deg) for 3
3
2
˚
Displacement Parameters (10 A ) for 1 C2H5OH
Distance
a
---
---
C(13) C(14)
Atom
x
y
z
Ueq
N(1) C(11)
1.386(2)
1.382(2)
1.511(2)
1.363(2)
1.434(2)
1.499(2)
1.402(2)
1.413(2)
1.380(2)
1.404(2)
1.385(2)
1.388(2)
---
---
N(1) C(18)
C(13) C(18)
---
C(1) C(11)
---
C(14) C(15)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
3260(1)
4111(1)
4204(1)
3982(1)
4186(1)
4033(1)
3666(1)
3450(1)
3605(1)
3793(1)
3861(1)
3346(1)
3164(1)
2628(1)
2273(1)
2441(1)
2982(1)
4370(1)
4424(1)
4912(1)
4894(1)
5256(1)
5104(1)
4605(2)
4244(1)
4390(1)
5377(1)
2912(1)
2631(2)
2099(2)
3911(3)
3967(3)
5158(3)
6789(3)
7586(3)
9126(4)
9915(3)
9134(3)
7581(3)
4194(3)
3422(3)
2597(3)
1603(3)
987(4)
1341(3)
2327(3)
2942(3)
3359(4)
4193(3)
3340(3)
2535(3)
1465(4)
865(4)
3551(2)
5850(2)
3821(3)
4175(3)
5162(3)
5405(3)
4653(3)
3685(3)
3448(3)
3114(3)
2063(3)
1831(2)
925(3)
29(1)
32(1)
26(1)
25(1)
29(1)
34(1)
33(1)
34(1)
28(1)
26(1)
28(1)
27(1)
33(1)
39(1)
38(1)
32(1)
26(1)
38(1)
28(1)
31(1)
30(1)
37(1)
45(1)
42(1)
36(1)
30(1)
41(1)
44(1)
56(1)
80(1)
---
---
C(11) C(12)
C(15) C(16)
---
C(12) C(13)
---
C(16) C(17)
---
---
C(12) C(19)
C(17) C(18)
Angles
---
---
---
---
C(11) N(1) C(18) 109.02(13) C(2) C(1) C(21) 112.95(13)
--- --- --- ---
C(21) N(2) C(28) 109.06(12) C(11) C(1) C(21) 112.11(12)
--- ---
C(2) C(1) C(11) 112.33(12)
C(7)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
O(30)
C(31)
C(32)
---
17.2 and 94.2 for 3. The N O distances in
1 C2H5OH of 2.930(4) and 3.006(3) A are typ-
˚
---
981(3)
ical of those generally observed for N H
O
1920(3)
2841(3)
2784(3)
1295(3)
4829(3)
4914(3)
6033(3)
6604(3)
7691(3)
8240(3)
7711(3)
6590(3)
4024(4)
5897(2)
6042(4)
5289(6)
bonding31 and, in particular, similar to the
˚
---
N O distance of 3.155(4) A observed for
---
N H
O bonding of two pyrrolic NH groups
of Me8-calix[4]pyrrole to each of two methanol
molecules.32 There is no hydrogen bonding in
---
3 based on N(1) O(1) distances of 3.927 and
4.662 A, and a C(7) C(2) C(1) C(11) torsion
angle of 90.1 .
˚
---
---
---
1333(4)
2382(4)
2948(3)
3268(4)
5004(3)
6504(5)
6528(6)
The hydrogen-bound ethanol molecule in
1 C2H5OH illustrates how anion complexa-
tion might be achieved with di-and triindolyl-
methanes as is suggested by the strong down-
field shift of the NH proton resonances of 4
in chloroform-d solutions containing nBu4NF
or nBu4NI. Anion binding ability, as well
as ligating ability of 1–4 to main group
aUeq is defined as one third of the trace of the orthogonalized U
ij
tensor.
˚
Table 8. Selected Distances (A) and Angles (deg) for 4
Distance
---
---
C(3) C(4)
N(1) C(1)
1.372(2)
1.375(2)
1.368(2)
1.518(2)
1.436(3)
1.494(3)
1.409(3)
1.411(2)
1.369(3)
1.393(4)
1.384(3)
1.391(3)
---
---
N(1) C(8)
C(3) C(8)
---
---
C(4) C(5)
C(1) C(2)
---
---
C(1) C(10)
---
C(5) C(6)
---
C(6) C(7)
C(2) C(3)
---
---
C(2) C(9)
C(7) C(8)
Angles
---
---
---
---
C(1A) C(10) C(1B)
C(1) N(1) C(8)
109.14(14)
112.90(11)
C(1) C(10) C(1B)
112.90(12)
112.90(11)
--- ---
--- ---
C(1) C(10) C(1A)
aSymmetry transformations used to generate equivalent atoms: A: y, x y, z; B: x +
y, x, z.

Di- and triindolylmethanes
539
Table 10. Atomic Coordinates (104) and Equivalent Isotropic
Table 11. Atomic Coordinates (104) and Equivalent Isotropic
2
3
2
˚
Displacement Parameters (103 A ) for 3
Displacement Parameters (10 A ) for 2
˚
a
a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
Br(1)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2716(1)
4220(3)
4651(3)
2867(4)
1488(3)
984(4)
276(4)
1025(3)
587(4)
5463(1)
2639(3)
4531(3)
2557(3)
3270(3)
4551(4)
5183(4)
4534(4)
3256(4)
2632(4)
1947(4)
823(4)
1956(1)
1851(1)
749(1)
934(1)
1183(1)
987(2)
1210(2)
1634(2)
1831(2)
1609(2)
1359(2)
1321(2)
1812(2)
2013(3)
2529(3)
2841(2)
2658(2)
2139(2)
847(3)
546(1)
19(1)
74(1)
49(1)
49(1)
41(1)
40(1)
49(1)
52(1)
49(1)
50(1)
46(1)
46(1)
55(1)
60(1)
85(2)
92(2)
90(2)
72(1)
56(1)
86(2)
41(1)
44(1)
49(1)
66(1)
85(2)
86(2)
67(1)
50(1)
61(1)
O(1)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
8855(2)
9002(2)
6047(1)
7344(2)
8797(2)
9421(2)
10772(2)
11490(2)
10899(2)
9554(2)
9534(4)
7640(2)
6685(2)
7482(2)
7090(2)
8141(2)
9586(2)
10001(2)
8934(2)
5102(2)
6178(2)
5162(2)
4365(2)
3272(2)
2822(2)
3409(2)
4466(2)
4945(2)
4954(2)
18(1)
1490(1)
1743(1)
924(1)
6219(2)
5128(2)
6456(2)
6019(2)
7454(2)
8716(2)
9997(2)
10014(3)
8777(3)
7492(2)
6196(4)
4789(2)
3248(2)
2577(2)
1073(2)
812(2)
2020(2)
3516(2)
3782(2)
2404(3)
6440(2)
6909(2)
7256(2)
7865(2)
8185(2)
7875(2)
7241(2)
6956(2)
7104(3)
56(1)
33(1)
34(1)
32(1)
34(1)
44(1)
54(1)
56(1)
52(1)
40(1)
72(1)
31(1)
34(1)
32(1)
37(1)
40(1)
43(1)
40(1)
32(1)
51(1)
31(1)
33(1)
32(1)
38(1)
43(1)
43(1)
39(1)
32(1)
50(1)
790(1)
1137(1)
1016(1)
541(1)
188(1)
310(1)
C(6)
C(7)
C(8)
C(7)
675(4)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
3917(4)
4856(4)
5744(4)
6934(5)
7563(5)
7064(6)
5945(5)
5319(4)
4951(6)
3711(4)
3648(4)
4608(4)
4999(5)
6016(6)
6604(6)
6237(5)
5230(4)
2772(5)
523(1)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
1232(1)
1313(1)
1635(1)
1850(1)
2157(1)
2247(1)
2039(1)
1738(1)
1105(1)
1193(1)
962(1)
1389(1)
1407(1)
1898(1)
2375(1)
2369(1)
1873(1)
379(1)
819(4)
36(5)
302(6)
1400(7)
2247(6)
1947(4)
173(5)
3498(3)
3576(4)
4714(4)
5311(5)
6400(5)
6914(5)
6383(4)
5280(4)
2664(4)
178(2)
682(2)
691(3)
202(3)
310(2)
313(2)
396(2)
aUeq is defined as one third of the trace of the orthogonalized U
ij
aUeq is defined as one third of the trace of the orthogonalized U
tensor.
ij
tensor.
Table 12. Atomic Coordinates (104) and Equivalent Isotropic
2
and transition elements, is currently under
investigation.
Displacement Parameters (103 A ) for 4
˚
a
Atom
x
y
z
Ueq
Supplementary material
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
224(1)
611(1)
1568(1)
1776(1)
2610(2)
2542(2)
1680(2)
855(2)
918(1)
2253(2)
0
1590(1)
1186(1)
2000(1)
2973(1)
4066(2)
4811(2)
4519(2)
3451(2)
2690(1)
1894(3)
0
4585(2)
3581(2)
3054(2)
3763(2)
3675(2)
4508(2)
5422(3)
5553(2)
4711(2)
1956(3)
3152(3)
46(1)
44(1)
48(1)
45(1)
54(1)
63(1)
66(1)
56(1)
43(1)
80(1)
45(1)
Crystallographic data (excluding structure
factors) for the structures reported in this pa-
per have been deposited with the Cambridge
Crystallographic Data Centre as supplementary
publications CCDC 191640–191643. Copies of
available materials can be obtained, free of
charge, on application to The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK; e-mail:
deposit@ccdc.cam.ac.uk.
aUeq is defined as one third of the trace of the orthogonalized U
tensor.
ij

540
Mason, Barnard, Segla, Xie, and Kirschbaum
11. Trofimenko, S. Chem. Rev. 1993, 93, 943.
12. For pertinent examples of triindolylmethanes, see (a) Pindur,
U.; Flo, C. Arch. Pharm. 1990, 323, 79. (b) Pindur, U.; Mu¨ller,
J. Arch. Pharm. 1986, 319, 856. (c) Pindur, U.; Mu¨ller, J. Chem.
–Ztg. 1985, 109, 265. (d) Mu¨ller, J.; Pfeuffer, L.; Pindur, U.
Monatsh. Chem. 1985, 116, 365.
13. Verkade, J.G. Acc. Chem. Res. 1993, 26, 483.
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M.R.; Phulpagar, S.S.; Mashuta, M.S.; Richardson, J.F. Inorg.
Chem. 2000, 39, 3931.
Acknowledgments
Acknowledgment is made to the donors of the
Petroleum Research Fund, administered by the Amer-
ican Chemical Society (Grant No. 37172-AC3), for
partial support of this research. Financial support of
T.S.B. was generously provided by the University of
Toledo in the form of startup funds to M.R.M. Zeon
Chemicals L.P. is acknowledged for support of B.X.
We thank Bassam Fneich for experimental assistance.
The CCD facility of the Ohio Crystallography Consor-
tiumlocatedattheUniversityofToledowasestablished
with grants from the Ohio Board of Regents and
the ONR.
16. Dostal, V. Chem. Listy 1938, 32, 13. Chem. Abstr. 1938, 32,
5399.
17. v. Dobeneck, H.; Prietzel, H. Hoppe-Seyler’s Z. Physiol. Chem.
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50, 1765.
18. SMART, Software for the CCD Detector System; Siemens Ana-
lytical Instruments Division: Madison, WI, 1995.
19. SAINT, Software for the CCD Detector System; Siemens Ana-
lytical Instruments Division: Madison, WI, 1995.
20. Sheldrick, G. M. SADABS: Absorption Correction Program;
University of Go¨ttingen: Go¨ttingen, Germany, 1996.
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