New Bromine-Containing Bis(arylimino)acenaphthenes and Related Metal Complexes

Article abstract of DOI:10.1134/S1070328420030045

Abstract: The condensation reactions of 5-bromoacenaphthenequinone with 2,6-diisopropylaniline and 4?bromo-2,6-di-iso-propylaniline afford new mono- and tribromosubstituted bis(arylimino)acenaphthenes: 1,2-bis[(2,6-diisopropylphenyl)imino]-5-bromacenaphthene (Dpp-Br-Bian) (L¹) and 1,2-bis[(4-bromo-2,6-diisopropylphenyl)imino]-5-bromacenaphthene (p-Br-Dpp-Br-Bian) (L²), respectively. Compounds L¹ and L² act as neutral ligands in the [(Dpp-Br-Bian)ZnCl₂] (I), [(p-Br-Dpp-Br-Bian)AlCl₃] (III), and [(p-Br-Dpp-Br-Bian)GaCl₃] (IV) complexes synthesized by the reactions of free diimines with the corresponding metal chlorides. The reaction of the known dibromosubstituted derivative 1,2-bis[(4-bromo-2,6-di-iso-propylphenyl)iminoacenaphthene (p-Br-Dpp-Bian) (L³) with copper(I) chloride also affords complex [(p-Br-Dpp-Bian)CuCl] (II) with the neutral diimine ligand. New compounds L¹, L², and I–IV are characterized by NMR, IR spectroscopy, and elemental analysis. The molecular structure of complex I is determined by X-ray structure analysis.

Full text of DOI:10.1134/S1070328420030045

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2020, Vol. 46, No. 4, pp. 215–223. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Koordinatsionnaya Khimiya, 2020, Vol. 46, No. 4, pp. 195–203.
New Bromine-Containing Bis(arylimino)acenaphthenes
and Related Metal Complexes
a
a
a
a
a,
V. M. Makarov , T. S. Koptseva , V. G. Sokolov , V. A. Dodonov , A. A. Skatova *,
a
a
E. V. Baranov , and I. L. Fedushkin
a
Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Nizhny Novgorod, Russia
e-mail: skatova@iomc.ras.ru
Received October 3, 2019; revised October 23, 2019; accepted October 31, 2019
*
Abstract—The condensation reactions of 5-bromoacenaphthenequinone with 2,6-diisopropylaniline and
-bromo-2,6-di-iso-propylaniline afford new mono- and tribromosubstituted bis(arylimino)acenaphthenes:
4
1
1
,2-bis[(2,6-diisopropylphenyl)imino]-5-bromacenaphthene (Dpp-Br-Bian) (L ) and 1,2-bis[(4-bromo-
2
2
,6-diisopropylphenyl)imino]-5-bromacenaphthene (p-Br-Dpp-Br-Bian) (L ), respectively. Compounds
1
2
L and L act as neutral ligands in the [(Dpp-Br-Bian)ZnCl ] (I), [(p-Br-Dpp-Br-Bian)AlCl ] (III), and [(p-
2
3
Br-Dpp-Br-Bian)GaCl ] (IV) complexes synthesized by the reactions of free diimines with the correspond-
3
ing metal chlorides. The reaction of the known dibromosubstituted derivative 1,2-bis[(4-bromo-2,6-di-iso-
3
propylphenyl)iminoacenaphthene (p-Br-Dpp-Bian) (L ) with copper(I) chloride also affords complex [(p-
1
2
Br-Dpp-Bian)CuCl] (II) with the neutral diimine ligand. New compounds L , L , and I–IV are character-
ized by NMR, IR spectroscopy, and elemental analysis. The molecular structure of complex I is determined
by X-ray structure analysis.
Keywords: bromine, redox-active ligands, bis(arylimino)acenaphthenes, molecular structure, zinc, copper,
aluminum, gallium, complexes
DOI: 10.1134/S1070328420030045
INTRODUCTION
based on p-Br-Dpp-bian are efficient catalysts for
alkene polymerization [27, 28]. Taking into account
this fact together with the data on the unique proper-
ties of the nontransition metal complexes with
bis(arylimino)acenaphthenes, such as the reversible
cycloaddition of alkynes [16, 41], isothiocyanates [42],
and isocyanates [43] to the binuclear derivatives
Diimines, including conformationally rigid bis(aryl-
imino)acenaphthenes (Ar-bian), are widely used as
chelating ligands during the last decades in the chem-
istry of transition and nontransition metals. Although
the first reports on them appeared in the 1990s [1–4],
the study of these ligands is presently one of the prior-
ity trends in the chemistry of coordination com-
pounds, since the Lewis acidity of the related metal
complexes and, correspondingly, their reactivity can
be purposefully controlled due to the possibility of
varying the organic substituent at the nitrogen atom.
Numerous complexes of transition and nontransition
complexes based on Ar-bian [5] in which the ligand
can be in the neutral, mono-, di-, tri-, and tetraan-
ionic [6] states have been reported to the present time.
Many of these compounds were used as efficient cata-
lysts in the organic synthesis reactions [7–22] and in
the polymerization of olefins [23–33] and cyclic esters
[
(Dpp-bian)М–М(Dpp-bian)] (M = Ga, Al), the
capability of the gallium complex of undergoing the
two-electron oxidative addition of the substrate simi-
larly to the transition metals [44] and the capability of
the magnesium complex of one-electron reducing
organic halides and aromatic ketones [45, 46], we
believe that the synthesis of new bromosubstituted
ligands of the Ar-bian series is promising. These
ligands are interesting from the point of view of metal-
locomplex catalysis and also as precursors for the syn-
thesis of new acenaphthene-1,2-diimine derivatives.
The further functionalization of Ar-bian would pro-
vide their capability of forming 2D, 3D, and polymer
frameworks as a result of binding the functional
[
34–38].
In spite of great interest in using Ar-bian ligands in groups with the metal atoms due to both the redox-
coordination chemistry, only several representatives of active diimine fragment and redox-inactive functional
the bromosubstituted derivatives of this series are met groups. This seems perspective for the construction of
in the literature. In all cases, the bromine atoms are metal-organic frameworks (MOFs) based on redox-
located in the para positions of the aryl substituent at active organic ligands, examples of which are fairly
the nitrogen atom [24, 39, 40]. The nickel derivatives rare [47–49].
215

2
16
MAKAROV et al.
In this work, we report the synthesis of mono-, di-, was added. The precipitate formed was filtered off on
and tribromosubstituted bis(arylimino)acenaphthenes the Büchner funnel and washed with water. The
and the related zinc, copper(I), aluminum, and gal- formed solid substance with a 10% solution of soda
lium complexes. Acenaphthene-1,2-diimines con- (200 mL) was stirred at 80°С for 30 min, separated by
taining bromine atoms in the naphthalene moiety were filtration on the Büchner funnel, and washed with
synthesized for the first time.
water. The precipitate was extracted with a 4% aque-
ous solution of sodium bisulfate (500 mL) at 80°С for
3
0 min. The obtained filtrate was acidified with con-
EXPERIMENTAL
centrated sulfuric acid with permanent stirring to
Compounds I–IV are sensitive of oxygen and reach a weakly acidic pH of the solution. The precipi-
moisture and, hence, all manipulations on their syn- tated yellow substance was filtered off, consecutively
thesis and identification were conducted in vacuo washed with water and ethanol, and dried in vacuo.
using the Schlenk technique or in a nitrogen atmo- The yield was 9.4 g (76%), mp > 238 (decomp.).
sphere (Glovebox M. Braun). Toluene (Aldrich) was
dried and stored over sodium benzophenone. Pentane
1
Н NMR (200 MHz, DMSO-d , 300 K; J, Hz), δ,
6
ppm: 8.37 (d, 1Н, J = 8.2), 8.24–8.09 (m, 2Н), 8.04
d, 1Н, J = 7.6), 7.93 (d, 1Н, J = 7.2).
(
Aldrich) was dried over a sodium mirror and sampled
(
by condensation in vacuo prior to use. Other solvents
and reagents used for the synthesis of the organic com-
pounds were purified using commonly accepted pro-
cedures. Deuterobenzene (Aldrich) was dried over
sodium benzophenone and sampled by condensation
in vacuo into NMR tubes containing samples of the
–1
IR (ν, cm ): 2362 w, 1730 s, 1684 w, 1604 w,
1
576 w, 1507 w, 1304 w, 1268 w, 1209 w, 1117 w,
1
083 w, 1020 m, 943 w, 897 w, 847 w, 818 w, 794 w,
7
68 m, 724 w.
1
Synthesis of Dpp-Br-bian (L ). 5-Bromoacenaph-
studied compounds. 5-Bromacenaphthene was syn- thenequinone (3.0 g, 11.5 mmol) in acetic acid
thesized using the published procedure [50].
(50 mL) was heated to 118°С. A solution of 2,6-di-iso-
propylaniline (4.1 g, 23.1 mmol) in acetic acid (5 mL)
was added dropwise with permanent stirring to the
obtained hot solution for 1 h. As aniline was added, the
precipitate of 5-bromacenaphthenequinone was dis-
solved and the solution turned dark red. The reaction
mixture was refluxed for 4 h and then kept at 5°С for
IR spectra were recorded on an FSM-1201 spec-
–1
trometer in a range of 4000–450 cm (samples in
1
Nujol). H NMR spectra were detected on Bruker
DPX-200 (200 MHz) and Bruker Avance III
(
400 MHz) spectrometers. Melting points were deter-
mined in sealed evacuated capillaries. Elemental anal-
yses were carried out by the combustion of samples in
oxygen using the Pregel method.
2
4 h. The red precipitate formed was filtered off from
the solution, consecutively washed with water, etha-
nol, hexane, and diethyl ether, and dried in vacuo. The
yield was 5.6 g (84%), mp > 265 (decomp.).
1
Synthesis of 4-bromo-2,6-di-iso-propylaniline. Bro-
mine (12.1 g, 75.6 mmol) was added within 10 min to
a solution of 2,6-di-iso-propylaniline (13.4 g,
Н NMR (400 MHz, CDCl , 300 K; J, Hz), δ,
3
ppm: 8.10 (d, 1Н, J = 8.3), 7.62 (d, 1Н, J = 7.3), 7.48
7
5.7 mmol) in an ethanol–acetic acid (2 : 1) mixture
(
pt, 1Н), 7.31–7.27 (m, 5Н), 6.68 (d, 1Н, J = 7.3),
(
60 mL). The reaction mixture was stirred at room
6
.45 (d, 1Н, J = 7.8), 3.00 (sept, 4Н, J = 6.8), 1.24 (d,
2Н, J = 6.8), 0.98 (d, 6Н, J = 4.3), 0.97 (d, 6Н, J =
.3).
IR (ν, cm ): 1743 w, 1673 w, 1654 m, 1631 s,
temperature for 2 h. After the end of the reaction, a
1
4
2
0% aqueous solution of NaOH was added to the mix-
ture until a weakly alkaline pH was achieved. The
organic layer was extracted with diethyl ether (25 mL),
–1
washed with water two times, and kept over magne- 1579 m, 1523 m, 1425 m, 1361 w, 1348 w, 1324 m,
sium sulfate for 15 h. After the ether was removed, a 1270 w, 1237 w, 1223 w, 1188 m, 1167 w, 1108 w,
red-violet oily liquid of 4-bromo-2,6-di-iso-pro- 1091 m, 1043 m, 1022 m, 975 w, 960 w, 938 w, 890 w,
pylaniline was formed. The yield was 18.9 g (97%).
875 w, 862 s, 836 m, 816 w, 803 w, 781 s, 746 m, 726 w.
1
Н NMR (200 MHz, CDCl , 300 K; J, Hz), δ,
3
For C H N Br
ppm: 7.17 (s, 2Н), 3.87 (s, 2Н), 2.92 (sept, 4Н, J =
.8), 1.29 (d, 12Н, J = 6.8).
IR (ν, cm ): 3492 w, 3405 w, 2360 w, 2337 w, Found, %
620 m, 1575 w, 1243 w, 1209 w, 866 m, 838 w, 670 w.
The spectra correspond to the published data [51].
42 45
2
6
Anal. calcd., %
C, 76.70
C, 76.67
H, 6.90
H, 6.88
–1
1
2
Synthesis of p-Br-Dpp-Br-bian (L ). A solution of
Synthesis of 5-bromacenaphthenequinone. Sodium 5-bromacenaphthenequinone (3.0 g, 11.5 mmol) in
bichromate dihydrate (23.9 g, 80.2 mmol) was added acetic acid (50 mL) was heated to 118°С. A solution of
by small portions with continuous stirring to a solution 4-bromo-2,6-di-iso-propylaniline (6.0 g, 23.4 mmol)
of 5-bromacenaphthene (11.0 g, 47.2 mmol) and in acetic acid (5 mL) was added dropwise for 1 h with
cesium chloride heptahydrate (0.5 g, 1.3 mmol) in permanent stirring to the obtained hot solution. As
acetic acid (50 mL) at 40°С for 1 h. The reaction mix- aniline was added, the precipitate of 5-bromacenaph-
ture was stirred at 40°С for 8 h, and cold water (1 L) thenequinone was dissolved and the solution turned
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
Vol. 46
No. 4
2020

NEW BROMINE-CONTAINING BIS(ARYLIMINO)ACENAPHTHENES
217
–
1
dark red. The reaction mixture was refluxed for 4 h
and then kept at +5°С for 24 h. The red precipitate
formed was separated from the solution by filtration,
consecutively washed with water, ethanol, hexane, and
diethyl ether, and dried in vacuo. The yield was 5.7 g
IR (ν, cm ): 1661 s, 1625 s, 1593 m, 1572 s,
495 m, 1417 m, 1397 w, 1365 w, 1347 m, 1326 m,
277 m, 1253 m, 1220 m, 1208 m, 1185 m, 1170 w,
130 m, 1118 m, 1106 w, 1096 w, 1074 w, 1043 w,
032 s, 974 s, 954 m, 937 m, 854 s, 823 m, 800 s, 785 s,
59 s, 729 s, 695 s, 661 m, 622 m, 594 w, 577 w, 564 w,
1
1
1
1
(
67%), mp > 215 (decomp.).
7
1
Н NMR (400 MHz, CDCl , 300 K; J, Hz), δ, 527 m, 486 m, 466 m.
3
ppm: 8.16 (d, 1Н, J = 8.5), 7.69 (d, 1Н, J = 7.8), 7.55
(
pt, 1Н, J = 7.6) 7.39 (s, 2Н), 7.38 (s, 2Н), 6.83 (d, 1Н, For C41.50H N Cl BrZn
2 2
45
Anal. calcd., %
Found, %
J = 7.0), 6.61 (d, 1Н, J = 7.8), 2.93 (sept, 4Н, J = 6.8),
C, 63.53
C, 63.48
H, 5.71
H, 5.68
1
6
.21 (d, 12Н, J = 7.0), 0.97 (d, 6Н, J = 4.7), 0.95 (d,
Н, J = 4.7).
–1
IR (ν, cm ): 1711 s, 1676 m, 1633 m, 595 w,
582 w, 1571 w, 1327 m, 1291 m, 1271 w, 1236 w,
209 w, 1187 m, 1171 w, 1148 w, 1093 w, 1047 w,
Synthesis of [(p-Br-Dpp-bian)CuCl] (II). Cop-
per(I) chloride (0.05 g, 0.5 mmol) was added to a solu-
029 w, 970 w, 942 w, 924 w, 865 m, 846 w, 824 w, tion of compound L (0.32 g, 0.5 mmol) in toluene
1
1
3
1
7
81 m, 750 w, 728 m, 627 w, 478 w.
(20 mL). The mixture was stirred at 60°С for 3 h. The
resulting blue solution was kept at 10°С for 24 h. The
precipitated blue crystals were decanted from the solu-
tion, washed with cold toluene, and dried in vacuo.
The yield of compound II was 0.30 g (81%).
For C H N Br
4
2
43
2
3
Anal. calcd., %
Found, %
C, 61.86
C, 61.85
H, 5.31
H, 5.28
1
Н NMR (200 MHz, C D , 298 K; J, Hz), δ, ppm:
6
6
3
Synthesis of p-Br-Dpp-bian (L ). A solution of ace-
7
.58 (s, 4Н), 7.20–7.11 (m, 2Н), 6.83 (d, 2Н, J = 6.4),
naphthenequinone (5.0 g, 27.5 mmol) in acetic acid
6
.64 (pt, 2Н), 3.42 (sept, 4Н, J = 6.4), 1.28 (d, 12Н,
(
50 mL) was heated to 118°С. A solution of 4-bromo-
J = 6.4), 0.76 (d, 12Н, J = 6.4).
2
,6-di-iso-propylaniline (14.5 g, 56.6 mmol) in acetic
acid (5 mL) was added dropwise for 1 h with perma-
nent stirring to the obtained hot solution. As aniline
was added, the precipitate of acenaphthenequinone
was dissolved and the solution turned dark red. The
reaction mixture was refluxed for 4 h and then kept at
–1
IR (ν, cm ): 1645 s, 1603 w, 1573 m, 1494 w,
1
365 w, 1327 s, 1281 m, 1232 w, 1223 m, 1187 s, 1149 w,
1
118 m, 1086 w, 1072 w, 1043 m, 1030 w, 943 m, 923 w,
8
88 w, 865 s, 845 w, 829 m, 819 s, 797 w, 776 s, 729 s,
+
5°С for 24 h. The orange precipitate formed was sep- 694 s, 617 m, 533 m, 499 w, 465 s.
arated from the solution by filtration, consecutively
washed with water, ethanol, hexane, and diethyl ether, For C42H44N2ClBr2Cu
and dried in vacuo. The yield was 14.3 g (79%).
Anal. calcd., %
C, 60.37
C, 60.34
H, 5.31
H, 5.29
1
Н NMR (200 MHz, CDCl , 300 K; J, Hz), δ, Found, %
3
ppm: 7.93 (d, 2Н, J = 8.3), 7.50–7.33 (m, 6Н), 6.78
d, 2Н, J = 7.1), 2.96 (sept, 4Н, J = 6.8), 1.21 (d, 12Н,
(
Synthesis of [(p-Br-Dpp-Br-bian)AlCl ] (III). A
mixture of diimine L (0.25 g, 0.34 mmol) and AlCl
0.045 g, 0.34 mmol) in toluene (5 mL) was stirred at
60°C overnight. Pentane (20 mL) was added to the
obtained dark orange solution. Orange crystals precip-
itated from a toluene–pentane (9 : 1) mixture. The
J = 6.8), 0.96 (d, 12Н, J = 6.8).
3
2
–1
3
IR (ν, cm ): 1722 m, 1678 w, 1649 m, 1597 w,
(
1
9
324 w, 1277 m, 1235 w, 1189 w, 1039 w, 1015 w, 944 w,
24 w, 862 m, 835 m, 822 w, 785 m, 722 w.
Synthesis of [(Dpp-Br-bian)ZnCl ] (I). Zinc chlo-
ride (0.06 g, 0.5 mmol) was added to a solution of
2
1
compound L (0.29 g, 0.5 mmol) in toluene (20 mL). yield of compound III was 0.21 g (62%).
The mixture was stirred at 60°С for 2 h. The obtained
orange solution was kept at 10°С for 24 h. The precip-
1
Н NMR (400 MHz, C D , 298 K; J, Hz), δ: 7.61
6
6
itated orange crystals were decanted from the solution, (d, 1H, J = 8.3), 7.52 (d, 4H, J = 8.5), 6.82 (d, 1H, J =
washed with cold toluene, and dried in vacuo. The
yield of compound I was 0.33 g (86%).
7
.5), 6.77 (d, 1H), 6.65 (pt, 1H, J = 7.8), 6.46 (d, 1H,
J = 7.8), 2.94 (br.s, 4H), 1.15 (d, 6H, J = 6.3), 1.14 (d,
1
Н NMR (200 MHz, C D , 298 K; J, Hz), δ, ppm: 6H, J = 6.3), 0.8 (d, 6H, J = 6.8), 0.77 (d, 6H, J = 6.8).
6
6
7
.62–7.50 (m, 1Н), 7.30–7.17 (m, 6Н), 7.15–6.97 (m,
Н), 6.70 (d, 1Н, J = 7.8), 6.62–6.55 (m, 2Н), 6.28
–1
IR (ν, cm ): 1674 m, 1661 m, 1634 m, 1595 m,
5
(
(
d, 1Н, J = 7.8), 3.77–3.55 (m, 4Н), 2.11 (s, 3Н), 1.47 1574 s, 1423 m, 1418 m, 1366 m, 1348 w, 1319 s,
d, 12Н, J = 6.4), 0.82 (d, 6Н, J = 2.8), 0.79 (d, 6Н, 1265 m, 1221 m, 1207 w, 1186 m, 1152 m, 1071 m,
J = 2.8).
1030 m, 972 s, 943 m, 889 w, 876 m, 864 m, 845 w,
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
18
MAKAROV et al.
Table 1. Crystallographic data and experimental and struc- Table 2. Selected bond lengths (Å) and bond angles (deg) in
ture refinement parameters for compound I
compound I
Bond
Parameter
Value
d, Å
Empirical formula
FW
Crystal system
Space group
C41.50H BrCl N Zn
Zn(1)–N(1)
Zn(1)–N(2)
Zn(1)–Cl(1)
Zn(1)–Cl(2)
N(1)–C(1)
N(2)–C(2)
C(1)–C(2)
Br(1)–C(8)
2.123(3)
2.135(3)
2.1905(14)
2.1861(13)
1.273(5)
1.269(5)
1.522(5)
1.917(4)
45
2
2
787.97
Trigonal
R3
298(2)
0.71073
23.0682(4)
23.0682(4)
39.1825(8)
90
Temperature, K
Radiation wavelength, Å
a, Å
b, Å
Angle
ω, deg
c, Å
α, deg
β, deg
γ, deg
N(1)ZnN(2)
Cl(2)Zn(1)Cl(1)
79.86(11)
122.39(6)
90
120
V, Å3
Z
ρcalc, g/cm3
μ, mm–1
1
8057.2(7)
18
.304
6
0°C overnight. All volatiles were removed in vacuo,
and diethyl ether (5 mL) was added. Orange crystals
precipitated from the ether solution. The yield of com-
pound IV was 0.24 g (65%).
1
1.770
1
Н NMR (400 MHz, C D , 298 K; J, Hz), δ, ppm:
6
6
F(000)
7326
7
.69 (br.s, 1H), 7.64 (d, 4H, J = 5.3), 6.86 (br.s, 1H),
Crystal size, mm
Measurement range over θ, deg
Indices of ranges
0.28 × 0.22 × 0.18
2.89–26.37
–28 ≤ h ≤ 28,
6
.77 (br.s, 1H), 6.52 (br.s, 1H), 6.15 (br.s, 1H), 3.27
(
br.s, 2H), 2.94 (br.s, 2H), 1.20 (br.s, 12H), 0.81 (br.s,
6H), 0.61 (br.s, 6H).
–
–
28 ≤ k ≤ 28,
48 ≤ l ≤ 48
–1
IR (ν, cm ): 1661 m, 1613 m, 1587 w, 1570 m,
1
418 m, 1366 s, 1350 m, 1321 m, 1304 w, 1277 w,
Number of measured reflections
Number of independent reflections
85468
1234 w, 1221 w, 1207 w, 1182 m, 1171 w, 1152 w, 1125 w,
092 w, 1071 w, 1061 w, 1036 w, 976 m, 943 w, 889 w,
64 m, 847 m, 822 m, 797 w, 785 m, 775 m, 750 m,
39 m, 698 w, 667 w, 631 w, 556 w, 532 w, 453 w, 403 w.
1
8148 (0.0483)
8
(Rint)
7
Number of reflections
5551
with I > 2σ(I)
For C H N Cl Br Ga
43
45
2
3
3
Absorption correction (max/min)
Data/restraints/parameters
GOOF
0.779/0.696
8148/92/490
1.064
Anal. calcd., %
Found, %
С, 56.92
С, 56.64
H, 5.06
H, 5.05
R , wR (I > 2σ(I))
0.0579, 0.1535
0.0905, 0.1724
1
2
X-ray structure analysis of compound I. The crystals
of compound I suitable for X-ray diffraction analysis
were obtained by crystallization from toluene. The
crystal chosen for analysis was covered with a mineral
oil (Aldrich), fixed on a glass capillary, and then
placed in a cold nitrogen flow of an Agilent Xcalibur E
R , wR (for all reflections)
1
2
Δρmax/Δρmin, e Å–3
0.920/–0.861
8
22 s, 806 w, 789 m, 779 s, 741 m, 638 w, 611 w, 604 w,
29 w, 496 vs, 484 vs.
diffractometer (ω scan mode, MoK radiation, λ =
α
5
0
.71073 Å). Experimental sets of intensities were inte-
grated using the CrysAlisPro program [52]. The struc-
For C H N Cl Br Al
50
53
2
3
3
ture was solved by a direct method and refined by full-
matrix least squares for F using the SHELXTL pro-
2
hkl
Anal. calcd., %
Found, %
С, 56.92
С, 56.93
H, 5.06
H, 4.98
gram package [53] in the anisotropic approximation
for non-hydrogen atoms. Hydrogen atoms were placed
in geometrically calculated positions and refined iso-
tropically. An absorption correction was applied using
the SCALE3 ABSPACK program [54]. The bromine
Synthesis of [(p-Br-Dpp-Br-bian)GaCl ] (IV). A
mixture of diimine L (0.25 g, 0.34 mmol) and GaCl
3
2
3
(0.060 g, 0.34 mmol) in toluene (5 mL) was stirred at and hydrogen atoms were disordered over positions 5
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NEW BROMINE-CONTAINING BIS(ARYLIMINO)ACENAPHTHENES
а)
219
(
7
4
3
2
1
(b)
8
7
3
2
1
δ, ppm
1
1
Fig. 1. Н NMR spectrum of compound L (400 MHz,
CDCl , 298 K).
3
and 6 of the acenaphthene fragment. The solvate mol-
ecules of toluene and benzene in the partial positions
(
on the inversion center and on the rotation axis С ,
3
respectively) were found in the crystal of compound I.
The main crystallographic characteristics and the
experimental parameters of X-ray structure analysis
for compound I are presented in Table 1. Selected
bond lengths and bond angles are given in Table 2.
7
3
2
1
(
c)
The structure of compound I was deposited with
the Cambridge Crystallographic Data Centre (CIF
file CCDC no. 1957209; ccdc.cam.ac.uk/getstruc-
tures).
RESULTS AND DISCUSSION
5-Bromoacenaphthenequinone (76%) was synthe-
sized by the oxidation of 5-bromoacenaphthene with
sodium bichromate in acetic acid in the presence of
cerium chloride (40°C, 9 h). The compound was char-
acterized by NMR and IR spectroscopy. The subse-
quent condensation of 5-bromoacenaphthenequinone
with 2,6-di-iso-propylaniline in a ratio of 1 : 2 in acetic
acid (118°C, 4 h) (Scheme 1) gave 1,2-bis[(2,6-di-iso-
propylphenyl)imino]-5-bromoacenaphthene mono-
bromosubstituted at the naphthalene moiety (Dpp-
7
3
2
1
δ, ppm
1
Br-bian) (L ). The reaction product was isolated as a
1
Fig. 2. Н NMR spectra of compounds (a) I, (b) II, and
c) III ((a, b) 200 and (c) 400 MHz, C D , 298 K).
finely crystalline red powder in a yield of 84%. A sim-
ilar reaction of 5-bromoacenaphthenequinone with
(
6
6
4
-bromo-2,6-di-iso-propylaniline afforded the tribro-
mosubstituted derivative 1,2-bis[(4-bromo-2,6-diiso- (Scheme 1). Note that bis(arylimino)acenaphthenes
2
propylphenyl)imino]-5-bromoacenaphthene (L ) as a bromosubstituted at the naphthalene moiety
finely crystalline red substance in a yield of 67% were synthesized for the first time. The condensation
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
20
MAKAROV et al.
of 4-bromo-2,6-di-iso-propylaniline with un- acid was used as a solvent instead of toluene, which
substituted acenaphthenequinone gave the known shortened the reaction time from 3 days to 4 h.
1
3
compound 1,2-bis[(4-bromo-2,6-di-iso-propylphe- The synthesis of compounds L –L is presented in
3
nyl)imino]acenaphthene (L ) [28]. However, acetic Scheme 1.
Y
O
O
iPr
iPr
iPr
iPr
NH2
1
N
N
L : X = Br; Y = H;
iPr
iPr
CH3COOH
18°C; 4 h
+
2
L : X = Br; Y = Br;
1
X
L3: X = H; Y = Br
X
Y
Y
Scheme 1.
1
2
1
2
The IR spectra of new compounds L and L
The H NMR spectrum of compound L exhibits
–
1
1
1
exhibit absorption bands at 1654, 1632 cm (L ) and the same set of signals as that for compound L : the
711, 1676 cm–1 (L ) corresponding to stretching
2
methine protons of the iso-propyl substituents appear
as the septet at δ 2.93 (4Н) ppm, and the protons of the
methyl groups of the iso-propyl substituents are
observed as two overlapped doublets (δ 0.97 (6Н),
1
vibrations of the C=N double bonds.
1
1
The H NMR spectrum of compound L (Fig. 1)
contains signals of the iso-propyl groups of the 2,6-
iPr C H substituents: the doublet of the doubled
0
.95 (6Н) ppm) and the doublet of the doubled inten-
1
sity at δ 1.21 ppm (12H). Unlike compound L , the
2
6
3
aromatic protons of the 4-Br-2,6-iPr -C H substitu-
2
6
2
intensity (δ 1.24 (12Н) ppm) and two overlapped dou-
blets (δ 0.98 (6Н) and 0.97 (6Н) ppm) of the protons
of eight methyl groups and the septet of the doubled
intensity (δ 3.00 (4Н) ppm) of four methine protons.
The signals of five protons of the naphthalene moiety
diverge and appear as four doublets (δ 8.10 (1H), 7.62
1H), 6.68 (1H), and 6.45 (1H) ppm) and the pseudo-
triplet at δ 7.48 (1H) ppm. The aromatic protons of the
,6-iPr C H substituents are presented by the multi-
2
ents in complex L are presented by two singlets at δ
7
.39 (2Н) and 7.38 (2Н) ppm. The signals of the pro-
tons of the naphthalene moiety are observed as four
doublets at δ 8.16 (1Н), 7.69 (1Н), 6.83 (1Н), and 6.61
(
1Н) ppm and the pseudotriplet at δ 7.55 (1Н) ppm.
1
The reaction of compound L with zinc chloride
(
(
Scheme 2) occurs in toluene at 60°С for 2 h. Orange
crystals of compound [(Dpp-Br-bian)ZnCl ] (I) were
2
2
2
6
3
obtained by keeping the reaction mixture at 10°С for
plet in a range of 7.31–7.27 (5Н) ppm.
24 h (86% yield).
Ar
N
Ar
N
Cl
Cl
+
ZnCl2
Zn
Toluene
Br
Br
N
N
1
Ar
Ar (I)
(
L )
Ar = 2,6-iPr C H
2
6
3
Scheme 2.
1
The H NMR spectrum of compound I in deutero- complex I: two overlapped doublets at δ 0.82 (6Н) and
benzene (Fig. 2a) contains the same set of signals as free 0.79 (6Н) ppm, the doublet at δ 1.47 (12Н) ppm, and the
1
multiplet of overlapped signals of the methine protons
bis(imino)acenaphthene L . The signals of the protons of
(
δ 3.77–3.55 (4Н) ppm). The doublets at δ 6.28 (1Н)
the methyl groups of the 2,6-iPr C H substituents of
2
6
3
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NEW BROMINE-CONTAINING BIS(ARYLIMINO)ACENAPHTHENES
221
and 6.70 (1Н) ppm and the signals in ranges of δ 6.55– blue crystals of complex [(p-Br-Dpp-bian)CuCl] (II)
6
.62 (2Н), 7.17–7.30 (6Н), and 7.50–7.62 (1Н) ppm are were obtained by keeping the reaction mixture at 10°С
assigned to the aromatic protons of the naphthalene frag- for 24 h (81% yield).
ment and phenyl substituents at the nitrogen atoms. The
In the IR spectra of complexes I and II, the intense
crystalline cell of compound I contains the toluene mol-
ecule, whose signals are presented by the multiplet at absorption bands characteristic of the C=N bond
–1
δ 7.15–6.97 (5Н) and the singlet at δ 2.11 (3Н) ppm.
vibrations are observed at 1661 and 1625 cm and at
The reaction of compound L with copper(I) chlo- 1645 cm , respectively, indicating the neutral form of
3
–1
ride (Scheme 3) occurs in toluene at 60°С for 3 h. The the diimino ligand in these compounds.
Ar
N
Ar
N
+CuCl
Cu Cl
Toluene
N
N
3
Ar
Ar
(
L )
Ar = 4-Br-2,6-iPr C H
2
(II)
2
6
Scheme 3.
Since the molecule of compound II is symmetric, doublet at δ 6.83 (2Н), and pseudotriplet at δ 6.64
1
the H NMR spectrum of the complex (Fig. 2b) is (2Н) ppm are assigned to the protons of the naphtha-
simpler than the spectrum of complex I with the non- lene moiety.
1
symmetric ligand. The H NMR spectrum of com-
The reactions of aluminum and gallium chlorides
pound II exhibits the signals of the 4-Br-2,6-iPr C H
2
2
6
2
with diimine L (Scheme 4) in toluene afford com-
substituents: two doublets (δ 0.76 (12Н) and 1.28
pounds [(p-Br-Dpp-Br-bian)AlCl ] (III) and [(p-Br-
(
12Н) ppm), the septet at δ 3.42 (4Н) ppm of the iso-
propyl group, and the singlet at δ 7.58 (4Н) ppm of the
aromatic protons. The multiplet at δ 7.20–7.11 (2Н), from pentane in 62 and 65% yields, respectively.
3
Dpp-Br-bian)GaCl ] (IV) obtained as orange crystals
3
Ar
N
Ar
N
Cl
Cl
Cl
+
MCl3
M
Toluene
Br
Br
N
N
Ar
Ar
2
(
L )
M = Al (III), Ga (IV)
Ar = 4-Br-2,6-iPr C H
2
2
6
Scheme 4.
1
The Н NMR spectra of compounds III and IV are
The IR spectra of complexes III and IV are charac-
fairly complicated because of the nonsymmetric teristic of the neutral form of the Ar-bian ligand: the
1
–1
structures of these compounds. For example, the Н absorption bands at 1674, 1661 cm (III) and
–1
NMR spectrum of complex IV (Fig. 2c) contains five 1661 cm (IV), respectively, correspond to stretching
signals of five nonequivalent protons of the naphtha- vibrations of the C=N double bonds.
lene moiety of the ligand: the doublets at δ 7.61, 6.82,
According to the X-ray structure analysis data of
6
.77, and 6.46 and the pseudotriplet at 6.65 ppm. The complex I (Fig. 3), the coordination environment of
doublet at δ 7.52 ppm (4H) is assigned to the protons the zinc atom is a distorted tetrahedron. The bond
of the phenyl substituents at the nitrogen atoms, the lengths in the diimine fragment (N(1)–C(1) 1.273(5),
broadened singlet at 2.94 ppm (4H) is ascribed to the N(2)–C(2) 1.269(5), and C(1)–C(2) 1.522(5) Å) con-
methine protons of the isopropyl groups, and four firm the neutral state of the Dpp-Br-bian ligand. For
doublets at 1.15, 1.14, 0.8, and 0.77 ppm (6H each) are comparison, the N(1)–C(1), N(2)–C(2), and C(1)–
attributed to the protons to the CH groups of the iso- C(2) distances in the [(Cybu-bian)ZnCl ] derivative
3
2
propyl substituents. The NMR spectrum of com- (Cybu is cyclobutyl) with neutral diimine are 1.282(3),
pound IV contains a similar set of signals. 1.278(3), and 1.526(3) Å, respectively [55]. At the
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
22
MAKAROV et al.
ACKNOWLEDGMENTS
The authors are grateful to the Center for Collective Use
Analytical Center of the Razuvaev Institute of Organome-
tallic Chemistry of the Russian Academy of Sciences” for
using the scientific equipment.
“
N(1)
N(2)
Cl(2)
C(1)
Br
FUNDING
Zn
This work was supported by the Russian Science Foun-
dation, project no. 19-13-00336.
C(2)
CONFLICT OF INTEREST
Cl(1)
The authors declare that they have no conflicts of
interest.
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