N,N′-Disubstituted phenanthrene-9,10-diimines: Synthesis and NMR spectroscopic study

Article abstract of DOI:10.1016/j.tet.2011.12.028

Novel aryl-aryl, alkyl-alkyl, aryl-alkyl N,N′-disubstituted phenanthrene-9,10-diimines were synthesized by condensation of 9,10-phenanthrenequinone with primary amines. The novel two-stage method of synthesis of disubstituted phenanthrene-9,10-diimines wi

Full text of DOI:10.1016/j.tet.2011.12.028

Tetrahedron 68 (2012) 1422e1426
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
N,N0-Disubstituted phenanthrene-9,10-diimines: synthesis and NMR
spectroscopic study
*
Vladimir K. Cherkasov, Nikolay O. Druzhkov, Tatiana N. Kocherova, Andrey S. Shavyrin , Georgii K. Fukin
G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49st. Tropinina, 603950 Nizhny Novgorod, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Novel aryl-aryl, alkyl-alkyl, aryl-alkyl N,N0-disubstituted phenanthrene-9,10-diimines were synthesized
by condensation of 9,10-phenanthrenequinone with primary amines. The novel two-stage method of
synthesis of disubstituted phenanthrene-9,10-diimines with identical or different aryl and alkyl sub-
stituents at the nitrogen atom was established. The investigated compounds undergo slow Z-E/E-Z in-
terconversion which was studied by NMR spectroscopy. Thermodynamic parameters of interconversion
were obtained by variable temperature NMR spectroscopy.
Article history:
Received 26 August 2011
Received in revised form 28 November 2011
Accepted 12 December 2011
Available online 16 December 2011
Keywords:
Ó 2011 Published by Elsevier Ltd.
9,10-Phenanthrenequinone
N,N0-Disubstituted phenanthrene-9,10-
diimines
Z-E Interconversion
1. Introduction
different substituents at the nitrogen atom and evaluation of some
thermodynamic parameters of their Z-E/E-Z interconversion.
There is a considerable interest in molecules with an N]CeC]
N moiety due to their versatile coordination behavior and the in-
teresting properties of their complexes with metals. For example,
bis(imino)acenaphthenes (BIAN) are widely employed as ligands
and feature the rigidity and strain of the diazabutadiene moiety, the
stereoelectronic tunability of the substituents at nitrogen, and
facile ability to accept electrons.1
The majority of previously reported N,N0-disubstituted phen-
anthrene-9,10-diimines was synthesized by reductive cyclo-
dehydrogenation of benzyl-bis(arylimines).8 Prof. Li and co-
workers reported5 the synthesis of a new disubstituted phenan-
threne-9,10-diimine by interaction of 9,10-phenanthrenquinone
with 2,6-dimethylaniline by treatment of reagents with TiCl4/
DABCO at 140 ꢀC. We have established that this reaction can be
carried out under mild conditions with good yields. Compounds
1e6 were obtained by condensation of 9,10-phenanthrenequinone
with 6-fold excess of primary amines in the presence of equimolar
quantity of TiCl4 in toluene at 70 ꢀC (Scheme 1). The obtained
phenanthrene-9,10-diimines were isolated with 54e72% yields. All
compounds are yellow-red crystals, which are soluble in organic
solvents.
Recently a number of articles concerning complexes of transi-
tion and non-transition metals with unsubstituted2 and substituted
phenanthrene-9,10-diimine ligandsdstructural analogues of R-
BIAN, has been published. These complexes show biological activ-
ity,3 act as a DNA photocleavage agent,4 are employed as a catalysts
in the olefin polymerization5 and have interesting spectral and
redox6 properties, which can be used for building molecules with
intriguing electronic properties. Most of the investigations in this
field were carried out with unsubstituted or N,N0-diphenyl-
substituted phenanthrene-9,10-diimines, but there are also some
investigations dedicated to synthesis and complexes of N,N0-di-(2-
O
O
RN
NR
TiCl4
methylphenyl)-,
N,N0-di-(2,6-dimethylphenyl)-,
N,N0-di-(2,6-
2 H2NR
+
diisopropylphenyl)-substituted phenanthrene-9,10-diimines.5,7,8
- H2O
2. Results and discussion
Cl
t-Bu
1 ;
2 ;
3 ;
4 ;
5 ;
CF3
55%
6
R =
In this work we report the synthesis of novel N,N0-disubstituted
phenanthrene-9,10-diimine compounds with identical and
Cl
72%
53%
57%
Scheme 1.
62%
48%
* Corresponding author. E-mail address: andrew@iomc.ras.ru (A.S. Shavyrin).
0040-4020/$ e see front matter Ó 2011 Published by Elsevier Ltd.
doi:10.1016/j.tet.2011.12.028

V.K. Cherkasov et al. / Tetrahedron 68 (2012) 1422e1426
1423
In our earlier studies it was shown that mono-substituted phe-
nanthreneiminoquinones can be synthesized by condensation of
substituted anilines with 9,10-phenanthrenquinone in boiling meth-
anol in the presence of catalytic formic acid.9 No formation of phen-
anthrene-9,10-diimines has been observed under these conditions.
Applying this and the aforementioned methods step-by-step we have
synthesized phenanthrene-9,10-diimines having different aryl-aryl
(7) and aryl-alkyl (8) substituents in the imine groups (Scheme 2).
iPr
i-Pr
O
O
NH2
N
O
N
NR
iPr
iPr
+ H2NR
TiCl4
H+
+
i-Pr
iPr
7 ; t-Bu
8
R =
75%
73%
Scheme 2.
This two-stage process can be also used for the synthesis of
phenanthrene-9,10-diimines with identical substituents in order to
increase yield. The yield of compound 3 obtained by the two-stage
reaction reaches 82%, whereas yield of 3 obtained by the one-stage
process is 57%.
The diimines 2 and 8 were investigated by X-ray crystallography
(Fig. 1). According to it both diimines are E-Z isomers in the crystals.
The lengths of N]C double bonds in 2 and 8 vary in the range of
ꢀ
1.270(1)e1.277(1) A, which are typical for this type of compound.
The phenanthrene and N]CeC]N fragments in both molecules
are not planar as a result of steric repulsion between the 2,6-di-
methylphenyl substituents in 2 as well as 2,6-di-methylphenyl and
tert-butyl in 8. The torsion N(1)C(1)C(14)N(2) and N(1)C(1)C(2)N(2)
angles are ꢁ44.9ꢀ and ꢁ66.3ꢀ. The deviations of C(1), C(14) and
C(1), C(2) atoms in 2 and 8 from the phenanthrene fragments
ꢀ
ꢀ
mean plane are 0.289, 0.309 A and 0.406, 0.454 A, respectively.
The dihedral angles between C(2)eC(7) and C(8)eC(13) as well
as C(3)eC(8) and C(9)eC(14) fragments are 11.3ꢀ and 21.5ꢀ, re-
spectively, in 2 and 8.
The NMR spectra of 2,3,6e8 are rather complicated and features
two times more signals than expected for symmetrical structures
with identical N,N0 substituents at nitrogens. In order to explain the
obtained spectra we assume that investigated substances exist as
a mixture of E,Z and Z,E isomers (Scheme 3). In the case of slow
interconversion (according to NMR timescale) of 2,3,6e8 molecules
N,N0 substituents and all protons of phenanthrene fragment be-
came unequivalent. The greatest difference of the chemical shifts
was observed for protons H-1 and H-8 (Scheme 3, Fig. 2) in 2,3,6e8;
this occurs due to the influence of the aryl substituents ring
currents.
Fig. 1. Molecular structure of 2 and 8.
R'
R'
R
R
N
4
N
5
N
N
It is interesting to note that N,N0-(diphenyl)phenanthrene-9,10-
diimine, 1 and 5 exist in a form of symmetrical Z-Z isomers both in
solution and in the solid-state according to NMR spectra and X-ray
data7c of N,N0-diphenyl compound. In contrast compounds 2,3,6e8
provide NMR spectra of unsymmetrical compounds at room tem-
perature. Exchange between E-Z and Z-E forms is slow (in NMR
timescale) in a chloroform or DMSO solution at room temperature
for 2,3,6e8 and at 253 K for 4. Presence of exchange between E-Z and
Z-E isomers is confirmed by 2D NOESY NMR spectra. In the NOESY
spectra of phenanthrene-9,10-diimines intense ‘exchange’ cross-
peaks due to Z-E/E-Z interconversion are observed (Scheme 3, Fig. 2).
The chemical shifts of Z-E and E-Z isomers signals and the ratio
of isomers is equal for compounds with identical N,N0 substituents
2,3,6 and differ for compounds with different substituents 7,8
(Table 1). The content of symmetrical Z-Z isomer reaches only 1e5%
for 2,3,6e8.
1
8
2
7
3
6
E-Z
Z-E
Scheme 3.
Warming of solution of 2e4,6e8 leads to simplification of their
NMR spectra. Heating of 2e4 in DMSO results in NMR spectrum of
symmetrical diimine (E-Z and Z-E became indistinguishable) (Fig. 3).
In order to determine thermodynamic parameters of in-
terconversion we have conducted the series of NMR experiments
with variable temperature. The obtained parameters are shown in
Table 1. The rate constant of exchange for each temperature was
determined by lineshape analysis.10 Standard errors of estimations
were calculated from parameters of linear regressions.

1424
V.K. Cherkasov et al. / Tetrahedron 68 (2012) 1422e1426
investigations of Z-E interconversion mechanism and applying
the obtained ligands for the synthesis of complexes are being
explored.
4. Experimental
4.1. General
9,10-Phenantrenequinone, substituted anilines, and tert-
butylamine are commercially available products. Substituted
phenanthrene-9,10-diimines 1e35,8 were prepared by already
known5 modified method. The NMR spectra were recorded on
a
Bruker ‘Avance III’ NMR spectrometer (400 MHzd1H,
100 MHze13C) using DMSO or CDCl3 as the solvents and tetra-
methylsilane as the internal standard. IR-spectra were recorded
by FTIR spectrometer ‘Bruker Vertex 70’. Elemental analyses were
obtained on ‘EuroEA-3028-HT’. The X-ray data were collected on
an SMART APEX diffractometer (graphite-monochromated, Mo
ꢀ
K
a
-radiation,
u
- and
q
-scan technique,
l
¼0.71073 A) at 100 K.
The structures were solved by direct methods and were refined
on F2 using SHELXTL11 package. All non-hydrogen atoms were
found from Fourier syntheses of electron density and were re-
fined anisotropically. The H atoms in 2 were found from Fourier
syntheses of electron density and were refined isotropically,
whereas in 8 the H atoms were placed in calculated positions and
were refined in the riding model. SADABS12 was used to perform
area-detector scaling and absorption corrections. The details of
crystallographic, collection, and refinement data are shown in the
Supplementary data. CCDC-832612 (2) and 832613 (8) contains
the supplementary crystallographic data, which can be obtained
Fig. 2. NOESY spectrum of compound 8 (region of aryl protons). Peaks due to exchange
and diagonal are green, NOE peaks are blue. Some NOE peaks are suppressed due to
exchange. Tmix¼250 ms. One of the exchanging pairs is marked by boxes and arrow.
Table 1
Thermodynamic parameters of exchange obtained by variable temperature NMR. Energy of activation (Ea) was determined from Arrhenius plot (k¼A*eꢁEa/RT),
D D
H#, S#dfrom
Eyring plot (ln(k/T)¼ꢁ
D
H#/(RT)þ
D
S#/Rþ23.7600).
D
G#¼RT(23.760þln(T/k))
Compd
Tc, K
Dn, Hz
Ea, kCal/mol
D
G#, kCal/mol
D
H#, kCal/mol
D
S#, cal/(mol K)
ZE/EZ ratio
ZZ/EZ ratio
2
3
6
7
8
375
380
423
378
384
263
371
81.5
267
249
16.9ꢂ0.8
18.5ꢂ0.3
17.9ꢂ0.5
18.7ꢂ0.4
17.2ꢂ0.4
17.4ꢂ1.2
17.3ꢂ0.6
20.7ꢂ1.0
17.5ꢂ0.8
17.4ꢂ1.1
16.2ꢂ0.8
17.8ꢂ0.3
17.2ꢂ0.5
18.0ꢂ0.4
16.5ꢂ0.4
ꢁ1.3ꢂ1.3
1ꢂ0.7
1:1
1:1
1:1
1:0.75
1:0.14
5:100
3:100
2:100
2:100
3:100
ꢁ6.7ꢂ1.3
2.4ꢂ1.0
ꢁ0.6ꢂ1.4
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (internet.) þ44 1223 336 033;
e-mail: deposit@ccdc.cam.ac.uk.
T=303K
T=313K
T=333K
T=363K
T=403K
T=423K
T=428K
4.2. Phenanthrene-9,10-diimines with identical substituents
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10 ppm
1e6 were synthesized using the general procedure
Fig. 3. Temperature dependence of 6 tert-butyl NMR signals. Signal with the chemical
shift 1.25 ppm belongs to Z-Z isomer.
To stirred suspension of 9,10-phenantrenquinone (1.0 g;
4.8 mmol) and 6-fold excess of aniline or tert-butylamine in toluene
(30 mL) TiCl4 (0.5 mL; 4.8 mmol) was added dropwise. The stirring
was continued at ambient temperature during 10e20 h. Com-
pleteness of reaction was monitored by TLC. Resulting solution was
washed out to the neutral medium by water and then organic part
was separated and filtered. After removal of the solvent the crude
product was recrystallized from acetonitrile.
3. Conclusion
Some novel N,N0-disubstituted phenanthrene-9,10-diimines
were synthesized and a new two-stage method for their syn-
thesis was established. Applying this method allowed the syn-
thesis of disubstituted phenanthrene-9,10-diimines with not
only identical substituents but also with different aryl and alkyl
groups at nitrogen atom. The investigated compounds undergo
Z-E/E-Z interconversion, which was studied by NMR spectros-
copy. Thermodynamic parameters of interconversion were ob-
tained by variable temperature NMR spectroscopy. Further
4.2.1. 1. (N,N0-(2-Methyl)phenyl)phenanthrene-9,10-diimine. Orange
crystals. Mp¼150e151 ꢀC. Yield: 1.4 g (72%). Found (%): C, 87.16; H,
5.85; N, 7.20. Calculated for C28H22N2 (%): C 87.01; H, 5.74; N, 7.25.
IR (Nujol,
1286m,1220m,1191w,1181w,1166w,1154w,1123m,1115m,1046m,
n
/cmꢁ1): 1630m, 1614m, 1591s, 1574w, 1484m, 1324w,

V.K. Cherkasov et al. / Tetrahedron 68 (2012) 1422e1426
1425
1022w, 957m, 944m, 929w, 872w, 854w, 846w, 760s, 666m, 615s.
1H NMR (400 MHz, CDCl3,
/ppm, J/Hz): 1.59 (s, 3H, Me); 6.33e6.35
(m, 2H, PhH); 6.86e6.94 (m, 6H, PhH); 7.48 (m, 2H, H-3 and H-6);
7.60 (m, 2H, H-2 and H-7); 7.94 (d, 2H, H-4 and H-5, J¼8.1); 8.09 (d,
2H, H-1 and H-8, J¼7.6).
(d, 2H, H-1 and H-8, J¼6.0). 13C NMR (100 MHz, CDCl3,
d
/ppm): 117.1;
d
121.6; 121.7; 122.7; 123.9; 125.0; 126.6; 129.3; 129.4; 132.5; 134.5;
134.7; 149.2; 161.1.
4.2.6. 6. (N,N0-Di-tert-butyl)phenanthrene-9,10-diimine. Yellow crys-
tals, yield: 0.74 g (48%); mp¼126 ꢀC. Found (%): C, 83.02; H, 8.15.
4.2.2. 2. (N,N0-(2,6-Dimethyl)phenyl)phenanthrene-9,10-diimine.
Cherry red crystals, yield: 1.06 g (53%); mp¼166 ꢀC. Found (%): C,
86.92; H, 6.25; N, 6.71. Calculated for C30H26N2 (%): C, 86.92; H,
Calculated for C22H26N2 (%): C, 82.97; H, 8.23. IR (Nujol, n
/cmꢁ1):
1650s, 1636s, 1597m, 1360s, 1287w, 1264w, 1230s, 1207s, 1193m,
1162w, 1119w, 1074w, 1040w, 1027w, 1005w, 978w, 955m, 943w,
913w, 889w, 878w, 862w, 776m, 767m, 748s, 741m, 729s, 697m,
6.32. IR (Nujol,
1287w, 1241w, 1206m, 1176w, 1093w, 955w, 939w, 761s, 726s. 1H
NMR (400 MHz, CDCl3, /ppm, J/Hz): 1.37, 2.04 (s., both 3H,
n
/cmꢁ1): 1646m, 1624m, 1591m, 1490w, 1324w,
671m, 665m, 615m. 1H NMR (400 MHz, CDCl3,
d/ppm, J/Hz): 1.25,
d
1.47 (s, both 9H, t-Bu), 7.24 (m, 1H, H-3), 7.32 (m, 1H, H-7),
7.37e7.48 (m, 3H, H-1, H-2, H-6), 7.66, 7.68 (both d, 1Hþ1H, H-4,
H-5, J¼7.5), 7.85 (d, 1H, H-8, J¼7.5). 13C NMR (100 MHz, CDCl3,
PhMe); 6.70 (d, 1H, H-1, J¼7.8); 6.75e6.85 (m, 2Hþ1H, m-PhH, p-
Ph0H); 6.86 (m, 1H, p-PhH); 6.92 (m, 1H, H-2); 6.98 (d, 2H, m-
Ph0H, J¼7.5); 7.40 (m, 1H, H-3); 7.51 (m, 1H, H-7); 7.62 (m, 1H, H-
6); 7.90 (d, 1H, H-4, J¼7.9); 7.93 (d, 1H, H-5, J¼7.9); 8.32 (d, 1H, H-
d/ppm): 31.50, 31.52 (C(CH3)3), 57.9, 58.2 (C(CH3)3), 122.9, 124.7
(C(4)H, C(5)H), 126.2, 126.3 (C(3)H, C(8)H), 127.7, 129.9, 130.1 (C(1)
H, C(2)H, C(6)H), 128.6 (C(7)H), 134.3, 134.4, 135.9, 137.0 (C), 162.7,
164.7 (C]N).
8, J¼7.8). 13C NMR (100 MHz, CDCl3,
d/ppm): 17.2, 18.4 PhMe;
122.5, 123.1 p-Ph, p-Ph0; 123.5C(5)H, 124.6C(4)H; 124.9, 125.2,
126.8C; 126.9C(8)H; 127.4C(2)H; 127.6, 127.9 m-Ph, m-Ph0;
127.7C(1)H; 129.1C(7)H; 131.4C(3)H; 131.8C(6)H; 133.4, 134.0,
134.5C; 147.5, 148.9 PhN; 158.2, 159.9 C]N. Ph and Ph0 belongs to
nonequivalent N,N0 substituents.
4.3. Phenanthrene-9,10-diimines with different substituents
7,8 were synthesized using the general procedure
In the first stage was obtained N-(2,6-di-iso-propylphenyl)-
phenanthren-o-iminoquinone by known method.9 In the second
stage reaction of N-(2,6-di-iso-propylphenyl)-phenanthren-o-imi-
noquinone with a 3-fold excess of amine in the presence of TiCl4
was carried out during 3e5 h. Isolation and purification of products
were performed by method described above.
4.2.3. 3. (N,N0-(2,6-Diisopropyl)phenyl)phenanthrene-9,10-diimine.
Red crystals, yield: 1.44 g (57%); mp¼159 ꢀC. Found (%): C, 86.47; H,
8.11. Calculated for C38H42N2 (%): C, 86.65; H, 8.04. IR (Nujol, n/
cmꢁ1): 1644m, 1619m, 1597m, 1589m, 1435s, 1360m, 1325m,
1294m, 1285m, 1253m, 1220w, 1190w, 1169w, 1122w, 1104w,
1057w,1042w,1034w, 954m, 942m, 807w, 796w, 778m, 760s, 754s,
727s, 665m. 1H NMR (400 MHz, CDCl3,
d
/ppm, J/Hz): 0.59, 0.75,1.02,
4.3.1. 7. (N-(2,6-Dimethyl)phenyl-N0-(2,6-diisopropyl)phenyl) phen-
anthrene-9,10-diimine. Red crystals, yield: 1.69 g (75%); mp¼174 ꢀC.
Found (%): C, 86.63; H, 7.21. Calculated for C34H34N2 (%): C, 86.77; H,
1.14 (d, all 6H, PheCH(CH3)2, J¼6.7), 1.85, 2.81 (sept, both 2H,
PhCH(CH3)2, J¼6.7), 6.67 (d, 1H, H-1, J¼7.8), 6.80e6.98
(2Hþ1Hþ1H, m-PhH, p-Ph0H, p-PhH), 7.04 (m, 1H, H-2), 7.10 (d, 2H,
m-Ph0H, J¼7.5), 7.35 (m, 1H, H-3), 7.52 (m, 1H, H-7), 7.63 (m, 1H, H-
6), 7.90 (d, 1H, H-4, J¼7.9), 7.94 (d, 1H, H-5, J¼7.9), 8.30 (d, 1H, H-8,
7.28. IR (Nujol, n
/cmꢁ1): 1647m, 1615s, 1593s, 1463s, 1435s, 1361w,
1328m, 1288m, 1257w, 1245w, 1237w, 1217w, 1198m, 1168w,
1158w, 1120w, 1090w, 1058w, 1042w, 1033w, 986w, 954w, 940w,
922w, 835w, 820w, 804w, 780m, 758s, 727s, 688w, 665w. 1H NMR
J¼7.8). 13C NMR (100 MHz, CDCl3,
d/ppm): 22.5, 22.6, 23.5, 24.7,
27.3, 28.7, 122.4, 123.2, 123.3, 123.3, 124.0, 124.4, 127.0, 127.3, 128.7,
129.0, 129.4, 131.0, 131.7, 133.6, 134.0, 135.1, 135.3, 135.6, 144.9,
146.6, 158.9, 159.7.
(400 MHz, CDCl3, d
/ppm, J/Hz): 0.59, 0.79 (d, both 6H, CH(CH3)a2,
J¼6.7); 1.00, 1.14 (d, CH(CH3)2b, J¼6.7); 1.35 (s, PhMeb); 2.04 (s, 6H,
PhMea); 1.81 (sept, 2H, CH(CH3)2a, J¼6.7); 2.81 (sept, 2H, CH(CH3)b2,
J¼6.7); 6.66 (d, 1H, H-1b, J¼7.8); 6.72 (d, 1H, H-1a, J¼7.8); 6.75e7.01
(m-PhHa,b, p-PhHa,b, H-2a,b) 7.33e7.42 (m, H-3a,b), 7.51 (m, H-7a,b),
7.62 (m, H-6a,b); 7.91, 7.94 (m, H-4a,b,H-5a,b); 8.29 (d, H-8b, J¼7.8);
4.2.4. 4. (N,N0-(2,6-Dichloro)phenyl)phenanthrene-9,10-diimine. Red
crystals, yield: 1.48 g (62%); mp¼172e173 ꢀC. Found (%): C, 63.03;
H, 2.81; Cl, 28.63. Calculated for C26H14Cl4N2 (%): C, 62.93; H,
8.35 (d, H-8a, J¼7.8). 13C NMR (100 MHz, CDCl3,
d
/ppm): 17.3a, 18.5b,
2.84; Cl, 28.58. IR (Nujol,
n
/cmꢁ1): 1648m, 1628s, 1595m, 1557m,
22.6b, 22.8a, 23.5b, 24.1a, 27.4a, 28.8b, 122.5a, 122.5a, 122.9b, 123.1b,
123.3,123.4,123.5,124.1,124.5,124.6,125.0,127.1,127.2,127.3,127.4,
127.7, 127.9, 128.6, 128.8, 129.0, 129.7, 131.2a, 131.3b, 131.7b, 131.9a,
133.6, 134.1, 134.6, 135.2, 135.4, 135.6, 145.3a, 146.7b, 147.5a, 149.0b,
157.9b, 158.7b, 159.2a, 159.8a.
1434s, 1330m, 1298m, 1290m, 1264w, 1256w, 1226m, 1204w,
1193w, 1170w, 1149w, 1121w, 1098w, 1078w, 1062w, 1037w,
955w, 942m, 839w, 823w, 787m, 766s, 755s, 733m, 722s, 666m,
622m. 1H NMR (400 MHz, CDCl3,
d/ppm, J/Hz): 6.76e6.96 (m, 3H,
PhH); 6.97e7.20 (m, 3H, PhH); 7.21e7.37 (m, 2H); 7.39e7.72 (m,
3H); 7.90e8.01 (m, 2H); 8.17e8.58 (m, 1H). 13C NMR (400 MHz,
4.3.2. 8. (N-tert-Butyl-N0-(2,6-di-iso-propyl)phenyl) phenanthrene-
9,10-diimine. Yellow crystals, yield: 1.48 g (73%); mp¼109e110 ꢀC.
Found (%): C, 85.33; H, 8.15. Calculated for C30H34N2 (%): C, 85.26;
CDCl3,
d/ppm): 123.9, 124.4, 127.3e129.8, 132.0e133.4, 134.6,
161.9e162.6. 1H and 13C signals are widened. There are two sets
of signals observed in the PMR spectrum at 253 Kdone belongs
to Z-E isomer and another to ZZ isomer. The ratio of ZZ/EZ isomers
is 77:100.
H, 8.11. IR (Nujol, n
/cmꢁ1): 1648m, 1618m, 1597m, 1435w, 1360w,
1321m, 1289s, 1268s, 1255s, 1233m, 1210m, 1175s, 1156s, 1121s,
1007s, 1070s, 1055s, 1034s, 946s, 933m, 894s, 820s, 803s, 773m,
759w, 744w, 725w, 694m, 665w. 1H NMR (400 MHz, CDCl3,
4.2.5. 5. (N,N0-(3-Trifluoromethyl)phenyl)phenanthrene-9,10-diimine.
Orange crystals. Yield: 1.33 g (55%). Decomposed at 146 ꢀC. Found
(%): C, 68.19; H, 3.41. Calculated C24H12F6N2 (%): C, 68.02; H, 3.26. IR
d
/ppm, J/Hz): 0.86, 0.97 (d, both 6H, CH(CH3)a2, J¼6.7), 0.96 (s,
t-Bub), 1.11, 1.12 (d, both 6H, CH(CH3)2b, J¼6.7); 1.61 (s, 9H, t-Bua);
2.70e2.85 (m, CH(CH3)a2,b); 6.77 (d, 1H, H-1a, J¼7.8); 6.93 (m, 1H,
H-2a); 6.95e7.06 (m, PhHa,b); 7.19 (m, 1H, H-2b); 7.31 (m, 1H,
H-3a); 7.37* (d, 1H, H-1b); 7.38 (m, 1H, H-7a,b); 7.40* (H-3b); 7.44*
(H-7b); 7.47 (m, 1H, H-6a); 7.55 (m, 1H, H-6b); 7.72 (d, 1H, H-5a,
J¼7.9); 7.78 (d, 1H, H-4a, J¼7.9); 7.84 (d, 1H, H-5b, J¼7.9); 7.87 (d,
1H, H-4b, J¼7.9); 7.93 (d, H-8a, J¼7.8); 8.00 (d, 1H H-8b, J¼7.8).
Signals assigned to isomers a or b are marked by letters. Ratio of
isomers is 1:0.14 (a/b). Chemical shifts obtained from HSQC
(Nujol, n
/cmꢁ1): 1630m, 1617m, 1595s, 1483m, 1453s, 1328s, 1285s,
1226w, 1204w, 1177s, 1159s, 1116s, 1096s, 1066s, 1024m, 1001w,
982w, 958w, 947m, 890s, 802s, 764s, 752s, 742w, 699s, 669w, 659w,
640w, 617w, 596w, 542w, 528w, 517w, 474w, 461w. 1H NMR
(400 MHz, CDCl3,
PhH); 7.17 (m, 2H, PhH); 7.25 (m, 2H, PhH); 7.52 (m, 2H, H-3 and H-
d
/ppm, J/Hz): 6.51 (d, 2H, PhH, J¼7.8); 6.58 (m, 2H,
6); 7.66 (m, 2H, H-2 and H-7); 7.95 (d, 2H, H-4 and H-5, J¼7.9); 8.09

1426
V.K. Cherkasov et al. / Tetrahedron 68 (2012) 1422e1426
spectrum are marked by asterisk. 13C NMR (100 MHz, CDCl3,
/ppm): 22.3, 24.6 CH(CH3)2; 27.8 CH(CH3)2; 31.4C(CH3)3; 57.6
C(CH3)3; 122.9C(5)H; 123.3 PhH; 124.2C(4)H; 124.3 PhH;
126.6C(8)H; 127.0C(2)H, 127.3C(1)H; 129.0C(7)H; 130.4C(6)H;
130.6C(3)H; 132.1, 133.1, 136.2, 137.1, 144.9C; 161.0, 169.7 (C]N).
This spectrum is for isomer a only.
References and notes
d
1. Hill, N. J.; Vargas-Baca, I.; Cowley, A. H. J. Chem. Soc., Dalton Trans. 2009, 240e253.
2. (a) Dapporto, P.; Denti, G.; Dolcetti, G.; Ghedini, M. J. Chem. Soc., Dalton Trans.
1983, 779e782; (b) Pyle, A. M.; Chiang, M. Y.; Barton, J. K. Inorg. Chem. 1990, 29,
4487e4495; (c) Belser, P.; Zelewsky, A.; Zehnder, M. Inorg. Chem. 1981, 20,
3098e3103.
3. Pyle, A. M.; Rehmann, J. P.; Meshroyrer, R.; Kumar, C. V.; Turro, N. J.; Barton, J. K.
J. Am. Chem. Soc. 1989, 111, 3051e3058.
4. Pyle, A. M.; Long, E. C.; Barton, J. K. J. Am. Chem. Soc. 1989, 111, 4520e4522.
5. Li, L.; Jeon, M.; Kim, S. Y. J. Mol. Catal. A: Chem. 2009, 303, 110e116.
6. Shaffer, D. W.;Ryken, S. A.; Zarkesh, R. A.; Heyduk, A. F. Inorg. Chem. 2011, 50,13e21.
7. (a) van Belzen, R.; Klein, R. A.; Kooijman, H.; Veldman, N.; Spek, A. L.; Elsevier,
C. J. Organometallics 1998, 17, 1812e1815; (b) van Belzen, R.; Elsevier, C. J.;
Dedieu, A.; Veldman, N.; Spek, A. L. Organometallics 2003, 22, 722e736; (c) van
Belzen, R.; Klein, R. A.; Smeets, W. J. J.; Spek, A. L.; Benedix, R.; Elsevier, C. J. Recl.
Trav. Chim. Pays-Bas 1996, 115, 275e279.
Acknowledgements
The authors are thankful to Russian President Grant supporting
Scientific Schools (NSh-1113.2012.3, MD-915.2012.3), RFBR (Grant
N 10-03-00788), Program of Presidium of RAS N 18, 21 and FSP
‘Scientific and scientific-pedagogical cadres of innovation Russia’
for 2009e2013 years (GK P839 from 25.05.2010) for financial
support.
8. (a) MacPherson, E. J.; Smith, J. G. Tetrahedron 1971, 27, 2645e2649; (b) Ketet-
terer, A.; Ziller, J. W.; Rheinghold, A. I.; Heyduk, A. F. Organometallics 2007, 26,
5330e5338.
9. Abakumov, G. A.; Cherkasov, V. K.; Druzhkov, N. O.; Kurskii, Y. A.; Fukin, G. K.;
Abakumova, L. G.; Kocherova, T. N. Synth. Commun. 2006, 36, 3241e3247.
10. J. Rononczy. Bruker BioSpin TEDDY Dynamic NMR module v1.0.1.
11. Sheldrick, G. M. SHELXTL v. 6.12, Structure Determination Software Suite; Bruker
AXS: Madison, Wisconsin, USA, 2000.
Supplementary data
Supplementary data related to this article can be found online at
doi:10.1016/j.tet.2011.12.028.
12. Sheldrick, G. M. SADABS v.2.01, Bruker/Siemens Area Detector Absorption Cor-
rection Program; Bruker AXS: Madison, Wisconsin, USA, 1998.