Dicarbonyl chelates from 1-cymantrenylalkylamides: Formation, properties, and kinetics of the dark reaction with carbon monoxide

Article abstract of DOI:10.1007/s11172-015-0955-x

Photolysis of carboxamides with aminomethyl-, 1-aminoethyl-, and aminobenzylcymantrenes led to six-membered dicarbonyl chelates with the Mn - O bond, which are stable in solutions. In the presence of carbon monoxide, the chelates undergo a dark reverse reaction with the formation of the starting tricarbonyl complexes. It was found that the rate determining step of the thermal reaction of the chelates with CO was the chelate ring opening according to the S _N1 mechanism of ligand substitution.

Full text of DOI:10.1007/s11172-015-0955-x

Russian Chemical Bulletin, International Edition, Vol. 64, No. 4, pp. 914—922, April, 2015
914
Dicarbonyl chelates from 1ꢀcymantrenylalkylamides:
formation, properties, and kinetics of the dark reaction with carbon monoxide
E. S. Kelbysheva, L. N. Telegina, I. A. Godovikov, T. V. Strelkova, Yu. A. Borisov,
M. G. Ezernitskaya, B. V. Lokshin, and N. M. Loim
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: loim@ineos.ac.ru
Photolysis of carboxamides with aminomethylꢀ, 1ꢀaminoethylꢀ, and aminobenzylcymanꢀ
trenes led to sixꢀmembered dicarbonyl chelates with the Mn—O bond, which are stable in
solutions. In the presence of carbon monoxide, the chelates undergo a dark reverse reaction
with the formation of the starting tricarbonyl complexes. It was found that the rate determining
step of the thermal reaction of the chelates with CO was the chelate ring opening according to
the SN1 mechanism of ligand substitution.
Key words: cymantrene, amides, photolysis, dicarbonyl chelates, carbon monoxide,
photochromism.
Nowadays, a potential possibility of using photochroꢀ
mic materials in the development of photo devices, playꢀ
ing the role of molecular switches, memory elements, and
chemical sensors, stimulates research on the synthesis and
studies of photochemical properties of organic, inorganic,
and organometallic photochromic compounds.1—6 Reꢀ
cently,7—10 a possibility of application for this purpose of
cymantrene functional derivatives capable of forming reꢀ
versible photochromic systems due to the intraꢀ and interꢀ
molecular ligand exchange processes was demonstrated.
The key step of this type photochromic systems is the
thermoꢀ and/or photoinduced chelate ring opening in the
dicarbonyl chelates formed upon photolysis of cymanꢀ
trene functional derivatives (Scheme 1). The feasibility of
the ring opening depends on the lability degree of the coꢀ
ordination bond of the Mn atom with nꢀ or ꢀdonor groups
of the substituent. Earlier, it was shown that such groups
include pyridines,9,10 nitriles,11 alkenes,9,11 as well as keꢀ
tones8,9 and carbamates.7,9 To study the influence of the
nature of the carbonyl group in the cymantrene side chain
on the ability to form dicarbonyl chelates, in the present
work we considered a photochemical behavior of a numꢀ
ber of alkylꢀ and arylcarboxamides with aminomethylꢀ,
1ꢀaminoethylꢀ, and 1ꢀaminobenzylcymantrenes 1—6 and
kinetics of a reverse thermal reaction of chelates with
carbon monoxide.
The irradiation with a mercury lamp of the light yellow
solutions of amides 1—6 (Scheme 2) in benzene or THF
under argon led to the change of the color to crimson and
the registration of two absorption bands in the 400—550 nm
region of the electronic spectrum (Fig. 1, Table 1). A simꢀ
A
2.0
Scheme 1
1.5
1.0
1
2
0.5
400
500
600
700 /nm
Fig. 1. Electron absorption spectra of solutions of compounds 2
(1.2 mmol L–1) (1) and 8 (5 mmol L–1) (2) in benzene.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 0914—0922, April, 2015.
1066ꢀ5285/15/6404ꢀ0914 © 2015 Springer Science+Business Media, Inc.

Dicarbonyl chelates
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
915
Table 1. Calculated energy values and (CO) for compounds 1, 3, 7, 9, 18, and 19 and experimental data of IR and UV spectroscopy for
compounds 1—12
Comꢀ
pound
E
E´
(CO)/cm–1
(NH)
max/nm
/cm–1
(/L mol–1 cm–1

a.u.
Ligand
Amide,
experiment
Experiment
Calculations
1
7
7TS
18
2
8
3
9
9TS
19
4
10
5
11
6
12
–1931.8315045 –1931.636833
–1818.4725039 –1818.286140
–1818.4257301 –1818.240782
–1818.4294186 –1818.243795
2020, 1936
1930, 1857
1111—
1111—
2020, 1937
1930, 1859
2021, 1936* 2112, 2056, 2038
1932, 1859
1111—
2113, 2054, 2045
1690
1650
—
3419
3403
—
330 sh (986)
396 пл, 506 (327)
—
2053, 2003
—
2066, 2004
—
—
—
111111—
111111—
11—
11—
—
—
1675
1631
1685
1654
—
3444
3429
3419
3402
—
328 sh (1185)
438 (887), 533 (339)
331 (1309)
392 (146), 506 (67)
—
–1971.1423472 –1970.919407
–1857.787444 –1857.572879
–1857.7391427 –1857.525313
–1857.7430197 –1857.529172
2056, 2006
—
1111—
2068, 2015
—
—
—
111111—
111111—
111111—
111111—
111111—
111111—
11—
11—
11—
11—
11—
11—
2019, 1938
1930, 1859
2017, 1938
1929, 1857
2022, 1940
1930, 1858
—
—
—
—
—
—
1672
1632
1673
1628
1691
1650
3440
3424
3457
3445
3433
3388
332 (1697)
435 (437), 532 (147)
339 (2089)
427 (454), 493 (280)
330 (1086)
505 (349)
* The frequencies of two antisymmetric vibrations are identical.
ilar picture was observed earlier7 in the photolysis of relatꢀ
ed cymantrene carbamate derivatives, which resulted in
the formation of stable sixꢀmembered chelate complexes
with the Mn—O=CN bond.
(CO) and (NH) by 30—50 and 12—55 cm–1, respecꢀ
tively, is observed, that indicates the involvement of the
amide group in the stabilization of chelates 7—12 (see
Scheme 2). Besides, upon photolysis of amides 2, 4, and 6
the band of the noncoordinated amide group completely
disappears at the end of the reaction. Therefore, the phenyl
ring is not essentially coordinated to the manganese atom in
the intermediate 16ꢀelectron manganese carbonyl complex.
Scheme 2
1
The H NMR spectra of chelates 7—12 considerably
differ from the spectra of amides 1—6 and are well consisꢀ
tent with the structure of dicarbonyl sixꢀmembered cheꢀ
lates with the Mn—O=CN bond (Table 2). Similar changes
1
in the H NMR spectra were observed earlier7 for the
formation of carbamate chelates from tricarbonyl comꢀ
A
Comꢀ
pound
1, 7
2, 8
3, 9
R
R´
Comꢀ
pound
4, 10
5, 11
6, 12
R
R´
1939
0.8
0.7
H
H
Me
Me
Ph
Me
Me
Me
Ph
Ph
But
Me
1937
1859
2020
0.6
0.5
0.4
0.3
0.2
0.1
0
The IR monitoring of the photolysis of the amides
showed the disappearance of the MCO stretching vibraꢀ
tion bands of the starting complexes and the appearance
1675
of two bands of equal intensities at ~1930 and ~1858 cm–1
,
1633
corresponding to the symmetric and asymmetric stretchꢀ
ing vibrations of the CO ligands (Fig. 2, see Table 1). The
positions of these bands are virtually the same as the freꢀ
quencies of the CO ligands in the IR spectra of similar
carbamate chelates.7 At the same time, as in the case of
carbamates, the lowꢀfrequency shift of the amide group
–0.1
2000
1900
1800
1700
/cm–1
Fig. 2. IR monitoring of amide 2 photolysis in benzene.
Note. Figures 2 and 5 are available in full color in the onꢀline
version of the journal (http://www.springerlink.com).

916
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
Kelbysheva et al.
H
Table 2. Kinetic parameters of the dark reaction of chelates 7—12
and 17 with CO in benzene at 24 C
2.56
H
H
C
C
C
C
Exposed compound*
Chelate
kapp•104
/s–1 **

1/2
/min
N
H
H
C
C
H
CymCH2NHCOMe (1)
1 + 16
7
7 + 17
8
9
10
11
12
17
2.35(0.03)
2.38(0.08)
1.82(0.02)
0.89(0.01)
1.18(0.03)
1.03(0.01)
1.17(0.03)
52
53
64
129
103
115
99
H
C
CymCH2NHCOPh (2)
CymCH(Me)NHCOMe (3)
CymCH(Me)NHCOPh (4)
CymCH(Me)NHCOBut (5)
CymCH(Ph)NHCOMe (6)
16
C
H
C
C
O
O
H
O
>650
H
7
* Cym is cymantrene.
** A standard deviation is given in parentheses.
H
C
C
H
C
H
H
C
C
C
plexes. In particular, the transformation of compounds 1—6
to the corresponding dicarbonyl chelates 7—12 was acꢀ
companied by the downfield shift of the signals for the
ꢀprotons of the Cpꢀring, whereas the signals for the
ꢀprotons displace upfield. Besides, on going from chiral
amides 3—6 to chelates 9—12 the difference between the
chemical shifts of the diastereotopic ꢀH and ´ꢀH atoms,
as well as of ꢀ and ´ꢀprotons of the Cpꢀring, changes
(Fig. 3).
H
H
2.50
C
C
H
H
C
Mn
H
H
O
O
C
H
C
H
The structure of the dicarbonyl amide chelates was
confirmed by the DFT calculations of dicarbonyl comꢀ
plexes 7 and 9, for which the global energy minima turned
out to be higher than the energy of tricarbonyl amides 1
O
8
Fig. 4. The optimized structures of chelates 7 and 9. Indicated
are the interatomic distances (Å).
and 3 by 29 and 26 kcal mol–1, respectively (see Table 1).
The calculated geometrical parameters of the chelates have
values of principal bond lengths and bond angles standard
for cymantrene derivatives9,10 (Fig. 4). Besides, the calcuꢀ
lated frequencies (CO) in the IR spectrum qualitatively
agree with the experimental values (see Table 1).
b
Halfꢀtimes for amideꢀchelate transformation in 10 mM
solutions under similar conditions are close and equal to
~3 min. The evaluation of the quantum yield () of the
photoreaction of 1 in THF gives the value 0.8 0.1 relative
to the value  = 0.8 obtained earlier9,12 for the photolysis
of [(1ꢀallyloxyꢀ2ꢀpyridꢀ2ꢀylethyl)ꢀ5ꢀcyclopentadiꢀ
enyl](dicarbonyl)manganese.
Me
Me
Dicarbonyl chelates 7—12 are quite stable compounds
when stored in solutions under argon. Parameters of
their IR and H NMR spectra remain unchanged durꢀ
a
1
2ꢀCp
ꢀCp
´ꢀCp
ing 4 h at ~20 C and more than 12 h at 5 C. However,
attempts to isolate the chelates failed. The evaporaꢀ
tion of benzene or THF from the solutions leads to their
rapid decomposition and the formation of 1ꢀ and 2ꢀsubꢀ
stituted cyclopentadienes and polymeric products. In
particular, in the case of compounds 7 and 12 we
obtained the mixtures (~1 : 1) of, respectively, 1ꢀ and
NH
4.8 4.4
4.0 3.6 3.2 2.8
1.4 1.0

Fig. 3. 1H NMR spectra of compound 3 in benzeneꢀd6 before (a)
and after (b) irradiation (65% conversion of 3 to 9).

Dicarbonyl chelates
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
A
917
2ꢀ(acetamidomethyl)cyclopentadienes (13a and 13b) and
1ꢀ and 2ꢀ(1ꢀacetamidoꢀ1ꢀphenylmethyl)cyclopentadienes
(14a and 14b).
In the presence of carbon monoxide, chelates 7—12
undergo a reverse thermal reaction with the formation of
the starting tricarbonyl complexes; the halfꢀtimes of transꢀ
formation at 24 C are 60—130 min. The irradiation of the
dicarbonyl chelates with visible light in the 480—530 nm
range under the same conditions leads to a sharp acceleraꢀ
tion of the reverse reaction and the decrease of the halfꢀ
time to ~10 min. Threeꢀfive repetitions of the cycle: irraꢀ
diation of the amides and the subsequent dark reaction of
the chelates with CO did not lead to any changes in the IR
spectra of neither the starting amides, nor the chelate comꢀ
plexes. Therefore, a reversible photochromic pair between
the cymantrenylamides and the corresponding dicarbonyl
chelates exists in the reaction medium in the presence of
carbon monoxide.
Photolysis of amides 1—6 in the presence of 2—4 equiv.
of triphenylphosphine gives only amide chelates 7—12,
though a parallel formation of the corresponding dicarboꢀ
nylphosphine complexes could have been expected. This
means that the intramolecular chelation is a more effiꢀ
cient process than the intermolecular substitution of the
CO ligand. It should be noted that the dark thermal reacꢀ
tion of chelate 11 with carbon monoxide in the presence
of 2 equiv. of PPh3 does not lead to the dicarbonylphosꢀ
phine complex either. Thus, carbon monoxide is more
efficient ligand than PPh3. However, the irradiation of
compound 5 in the presence of 1.5 equiv. of PPh3 with the
immediate removal of forming CO from the reaction mixꢀ
ture makes it possible to obtain triphenylphosphine comꢀ
plex 15 in 56% yield (Scheme 3).
2040 2000
1950
1900
1850 /cm–1
Fig. 5. IR monitoring of transformation of compound 10 to 4 in
benzene at 24 C (60% conversion).
ln(A0/A)
0.6
0.5
0.4
0.3
0.2
0.1
0
0
20
40
60
80
100 t/min
Fig. 6. The ln(A0/A) dependence of the band at  = 1857 cm–1
on the conversion time of compound 11 to 5 for a 12 mM soluꢀ
tion in benzene at 24 C (R = 0.9996).
Scheme 3
1/A
4.0
A
0.60
0.55
0.50
0.45
0.40
0.35
0.30
1
3.5
2.0
2
The ligand exchange at the Mn atom in cymantrene
derivatives and related complexes can occur either by the
associative or the dissociative mechanism.10,13 To estabꢀ
lish the pathway of the reaction of amide chelates 7—12
with carbon monoxide, we studied the kinetics of this reꢀ
action in the dark in benzene at 24 C. Examples of the IR
monitoring of the reaction course and kinetic graphs are
given in Figs 5—7. In all the cases, the rate of the disapꢀ
pearance of the chelate for the equimolar amounts of reꢀ
agents is described by the first order equation with the
value R  0.999 (see Table 2).
0
20
40
60
80
100 t/min
Fig. 7. The kinetics of compound 11 consumption (1) and
the 1/A dependence of the band at  = 1857 cm–1 on the 11  5
conversion time (2) for a 12 mM solution in benzene at 24 C
(R = 0.992).

918
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
Kelbysheva et al.
Scheme 4
To confirm the first order, we studied the reaction rate
for the thermal reactions of related chelates with CO, pyꢀ
ridine, phosphines, and phosphites.
for the double concentration of CO. The double excess
of CO was achieved by the irradiation of a 1 : 1 mixture of
amide 1 and 1ꢀallyloxyethylcymantrene (16) in benzene
(Scheme 4). We found that the irradiation of compound
16 leads to the formation of chelate 17, which in the preꢀ
sence of CO is reverted to the starting complex with the
halfꢀtime >650 min, which is larger almost by an order of
magnitude than 1/2 for the transformation 7  1. In this
connection, after irradiation the concentration of carbon
monoxide in the reaction mixture remains about twice as
large as the concentration of chelate 7 until a 50% converꢀ
sion of the dark reaction was reached. The rate constant of
the disappearance of 7 and its halfꢀtime obtained in this
case are virtually the same as those for the reaction in the
absence of complex 17 (Fig. 8, see Table 2).
Scheme 5
The kinetic data obtained showed that the rateꢀdeterꢀ
mining step of the thermal reaction of chelates 7—12 with
CO is the chelate ring opening at the Mn—O bond with
the formation of the solvated manganese carbonyl comꢀ
plex (Scheme 5). Therefore, the ligand substitution in the
amide chelate follows the SN1 mechanism. This concluꢀ
sion agrees with the mechanism suggested earlier10,14,15
k2[CO] >> k–1
As it is seen from Table 2, for compounds 9 and 10 the
kapp values are half as large and the 1/2 values are twice as
large compared to the corresponding values for chelates 7
and 8. From this it follows that the introduction of the Me
group into the CH2 fragment of the chelates under considꢀ
eration noticeably affects the rate of the dark reaction.
This fact agrees with the results of the DFT calculations of
the activation energy of the chelate ring opening for comꢀ
pounds 7 and 9: 28.5 and 29.9 kcal mol–1, respectively.
Chelates 11 and 12 substituted at position C(1) of the side
chain also react at a lower rate than chelates 7 and 8. The
similar frequencies of stretching vibrations of the CO
ligands for chelates 7—12 (see Table 1) show that the
structure of the side chain does not affect the electronꢀ
donating properties of the O=CN ligand.16,17 Therefore,
the decrease in the kapp value on going from chelates 7 and 8
to complexes 9—12, apparently, is related not to the ligand
electron nature, but to the steric hindrance arising upon
the ring opening. In the case of compounds 9 and 10, such
a hindrance can arise due to the interaction between the
 H atoms of the Cpꢀring and the Me group at C(1) posiꢀ
tion of the side chain. In fact, the calculations of the geoꢀ
metrical parameters for chelates 7 and 9, as well as the
corresponding transition states 7TS and 9TS and the interꢀ
ln(A0/A)
1
2
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
60 t/min
Fig. 8. The ln(A0/A) dependence of the band at  = 1858 cm–1
on the time after irradiation of a 11.2 mM solution of 1 in benzꢀ
ene in the absence (1, R = 0.9998) and in the presence of 1 equiv.
of 15 (2, R = 0.9995) at 24 C.

Dicarbonyl chelates
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
919
H
O
H
H
H
H
C
C
C
C
C
H
C
N
O
C
C
H
C
H
H
H
H
C
H
N
C
H
C
2.36
H
C
C
H
C
H
C
2.62
C
H
H
O
Mn
Mn
C
H
H
C
H
H
C
O
C
O
O
7TS
9TS
H
C
H
C
H
H
C
H
H
H
H
C
C
C
H
C
H
??
C
O
O
C
C
C
H
H
C
C
H
2.31
C
H
3.01
H
C
C
O
H
Mn
C
Mn
H
C
C
H
H
C
H
H
C
C
O
H
O
O
18
19
Fig. 9. The optimized structures of transition states 7TS and 9TS and the intermediates 18 and 19. Indicated are the interatomic
distances (Å).
mediates 18 and 19, show that the distance between the
closest H atoms in the unsubstituted structures 7, 7TS,
and 18 is larger than in their homologs 9, 9TS, and 19 (see
Figs 4 and 9). It should be emphasized that the minimal
distance is observed in the intermediate 19, and it is 0.7 Å
shorter than in compound 18.
that the rateꢀdetermining step of the thermal reaction of
chelates with CO is the chelate ring opening following the
SN1 mechanism of ligand substitution.
Experimental
In conclusion, it was found that photolysis of amides
1—6, like that of cymantrenyl carbamates7 and ketones,8
led to the formation of thermodynamically stable dicarboꢀ
nyl chelates due to the coordination of the carbonyl group
to the Mn atom. The evaluation of the quantum yield of
photolysis of amide 1 in THF gives the value 0.7—0.9. The
process of the formation of chelates is accompanied by
a bathochromic shift of the first longꢀwavelength absorpꢀ
tion band from 330 to 530 nm. The structure of the cheꢀ
1
H and 13C NMR spectra were recorded on a Bruker Avance
400 spectrometer (400.13 and 100.61 MHz, respectively), using
the solvent as a reference,  relative to Me4Si, for benzene
 = 7.26). Signals in the H NMR spectra were assigned using
1
the 2D HH—COSY and HH—ROESY experiments. IR spectra
were recorded on a Magna 750ꢀIR (Nicolet) IR Fourierꢀtransꢀ
form spectrometer with a 2 cm–1 resolution in cuvettes. Kinetic
studies were carried out on a Tensor 37 (Bruker) FTIRꢀspecꢀ
trometer at 24 C. Mass spectra (EI) were obtained on Kratos
MS 890 and Finnigan POLARIS Q spectrometers (70 eV). UV
spectra were recorded on a Specord Mꢀ40 spectrophotometer.
Photochemical reactions carried out using an Hereaus TQ 150
immersion Hg lamp. Reaction progress and purity of products
were monitored by analytical TLC on Silufol UVꢀ245 plates
(Kavalier). Merck silica gel 60 was used for column chromatoꢀ
graphy. THF and benzene were purified by standard methods
and distilled over sodium benzophenone ketyl or metallic sodiꢀ
um under argon. NꢀAcetylꢀ1ꢀcymantrenylmethylamine (1),18
1
lates was confirmed by IR, UV, and H NMR spectroꢀ
scopy, as well as by DFT calculations using the B3LYP/6ꢀ
31G* method. It was found that amide chelates in the
presence of carbon monoxide undergo the dark thermal
reaction with recovery of the starting tricarbonyl comꢀ
plexes, thus forming the photochromic pairs. The kinetic
studies of the dark thermal transformation of chelates 7—12
to the corresponding starting tricarbonyl complexes showed

920
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
Kelbysheva et al.
Nꢀbenzoylꢀ1ꢀcymantrenylmethylamine (2),18 Nꢀacetylꢀ1ꢀ
cymantrenylethylamine (3),19 Nꢀbenzoylꢀ1ꢀcymantrenylethylꢀ
amine (4),19 and Nꢀpivaloylꢀ1ꢀcymantrenylethylamine (5)19
were synthesized as described earlier. Cymantrenyl phenyl
ketone and acetylcymantrene were obtained by known
methods.20,21
(t, 2 H, Ph, J = 7.2 Hz); 7.46 (d, 2 H, Ph, J = 7.6 Hz). 1H NMR
(benzeneꢀd6), : 1.57 (s, 3 H, Me); 3.72 (m, 1 H, H, Cp); 3.79
(m, 1 H, H, Cp); 4.05 (m, 1 H, H, Cp); 4.21 (m, 1 H, H, Cp);
5.32 (br.d, 1 H, NH, J = 7.5 Hz); 5.99 (d, 1 H, CH, J = 8.7 Hz);
7.03—7.15 (m, 5 H, Ph). IR (benzene), /cm–1: 3388, 2022,
1939, 1691 (NC=O). EAS (benzene, /nm (/L mol–1 cm–1)):
330 (1086). MS, m/z (Irel (%)): 267 [M – 3 CO]+ (100), 226 (22),
208 (17), 153 (42), 113 (79). Found (%): C, 58.18; H, 4.10;
Mn, 15.4; N, 3.94. C17H14MnNO4. Calculated (%): C, 58.13;
H, 4.02; Mn, 15.64; N, 3.99.
1ꢀAllyloxycymantrenylethane (16). Sodium borohydride
(2.8 g, 74 mmol) was added in portions to a solution of acetylcyꢀ
mantrene (18 g, 73 mmol) in EtOH (100 mL), and the mixture
was stirred for 1 h at 10 C. Then, the reaction mixture was
poured into the icy water and extracted with CH2Cl2 (3×100 mL),
the organic layers were washed with water and dried with
Na2SO4. The solvent was evaporated, 1ꢀcymantrenylethanol (21)
was isolated by column chromatography (AcOEt—hexane
(1 : 1)). The yield was 17.0 g (94%), m.p. 51—52 C (cf. Ref. 22:
m.p. 55—56 C). 1H NMR (CDCl3), : 1.50 (d, 3 H, Me,
J = 6.4 Hz); 4.64 (q, 1 H, CH, J = 6.3 Hz); 4.70 (m, 1 H, H,
Cp); 4.75 (m, 1 H, H, Cp); 4.87 (m, 1 H, H, Cp); 4.93 (m, 1 H,
H, Cp).
NꢀAcetylꢀ1ꢀcymantrenylꢀ1ꢀphenylmethylamine (6). A mixture
of cymantrenyl phenyl ketone (15 g, 48.7 mmol), NH2OH•HCl
(5.1 g, 73 mmol), and sodium acetate (8.0 g, 97.4 mmol) in
EtOH (100 mL) was refluxed for 6 h using a reflux condenser.
Then, the reaction mixture was cooled to ~20 C and concenꢀ
trated in vacuo to 1/4 of the volume. After addition of water
(100 mL) to the residue, the product was extracted with AcOEt
(100 mL), the organic layers were washed with (3×100 mL) and
a saturated aqueous NaCl, dried with MgSO4, the solvent was
evaporated. The residue was crystallized from hexane with AcOEt.
The yield of cymantrenyl phenyl ketone oxime (20) was 12.0 g
(76%), m.p. 132—133 C, a mixture of two isomers in the ratio of
1
1 : 0.9. H NMR (acetoneꢀd6), , major isomer: 5.45 (m, 2 H,
H, Cp); 5.59 (m, 2 H, H, Cp); 7.83—7.97 (m, 5 H, Ph); 10.89
(s, 1 H, NOH); minor isomer: 5.51 (m, 2 H, H, Cp); 5.96 (m, 2 H,
H, Cp); 7.83—7.97 (m, 5 H, Ph); 11.62 (s, 1 H, NOH). Found (%):
C, 55.81; H, 3.09; Mn, 17.1; N, 4.39. C15H10MnNO4. Calculatꢀ
ed (%): C, 55.75; H, 3.12; Mn, 17.0; N, 4.33.
A solution of compound 21 (3.0 g, 12 mmol) in THF (50 mL)
was added dropwise to a suspension of 60% NaH (0.8 g, 20 mmol)
in hexane (7 mL) at 0 C under argon, and the mixture was
stirred for 15 min. Then, a solution of allyl bromide (1.6 mL,
20 mmol) in THF (10 mL) was added to the suspension through
the septum. The reaction temperature was raised to ~20 C, and
the mixture was stirred for 3 h and neutralized with 10% aqueous
solution of NH4Cl (50 mL). The layers were separated and the
aqueous layer was extracted with AcOEt (3×100 mL). The orꢀ
ganic layers were combined, washed with saturated aqueous NaCl
(100 mL), and dried with Na2SO4. The solvent was evaporated,
the product was isolated by column chromatography (AcOEt—
hexane (1 : 3)). The yield was 2.7 g (77%). 1H NMR (acetoneꢀd6),
: 1.38 (d, 3 H, Me, J = 6.4 Hz); 4.09 (m, 2 H, CH2); 4.26
(q, 1 H, CH, J = 6.4 Hz); 4.84 (m, 1 H, H, Cp); 4.86 (m, 1 H,
H, Cp); 5.07 (m, 1 H, H, Cp); 5.09 (m, 1 H, H, Cp);
5.12 (m, 1 H, =CH2); 5.31 (m, 1 H, =CH2); 5.92 (m, 1 H,
=CH). 1H NMR (benzeneꢀd6), : 1.08 (d, 3 H, Me, J = 6.4 Hz);
3.71—3.74 (m, 2 H, CH2O); 3.74 (q, 1 H, CH, J = 6.4 Hz);
3.84 (m, 1 H, H, Cp); 3.86 (m, 1 H, H, Cp); 4.21 (m, 1 H, H,
Cp); 4.31 (m, 1 H, H, Cp); 5.03 (dm, 1 H, =CH2, J = 10.5 Hz);
5.21 (dm, 1 H, =CH2, J = 17.2 Hz); 5.80 (m, 1 H, =CH). IR
(hexane), /cm–1: 2026, 1944. Found (%): C, 54.54; H, 4.71;
Mn, 18.6. C13H13MnO4. Calculated (%): C, 54.18; H, 4.55;
Mn, 19.0.
Spectral studies of photochemical reactions of tricarbonyl comꢀ
plexes and a reverse dark reaction (general procedure). A solution
of a tricarbonyl compound (2—4 mmol L–1) in a required solꢀ
vent (benzene or THF) was placed in an IR or a UV cell under
argon and irradiated with both nonfiltered light and at  = 365 nm
using a mercury lamp (before irradiation, the lamp was brought
out to the regime for 2 min). The spectra were recorded every
2—4 min. The total irradiation time for all the samples was
10—25 min. To obtain the samples for monitoring by NMR, the
solutions of compounds (10—15 mmol L–1) were filtered into
the NMR tubes, the solutions were bubbled with argon and irraꢀ
diated with a mercury lamp for 4 min at 8—10 C until a 25—40%
conversion was reached. The distance between the lamp and the
sample in all the cases was 5 cm, 1H NMR spectra were recorded
Zinc dust (11.0 g, 167 mmol) was added in portions to
a solution of compound 20 (10.8 g, 33.4 mmol) in a mixture of
acetic acid (125 mL) and water (12 mL). Then, the reaction
mixture was refluxed for 3 h, cooled to 80 C, and filtered.
A precipitate was washed with acetic acid. The combined soluꢀ
tions were neutralized to pH 9 with a 25% aqueous ammonia and
extracted with diethyl ether (300 mL). The organic layers were
washed with 2 N NaOH (50 mL), dried with MgSO4, and the
solvent was evaporated. The residue was separated by column
chromatography (AcOEt—hexane (5 : 3)) to isolate four products.
Acetoxyꢀ1ꢀcymantrenylꢀ1ꢀphenylmethane. The yield was
810 mg (7%), m.p. 78—79 C (hexane). 1H NMR (acetoneꢀd6),
: 2.13 (s, 3 H, Me); 4.88 (m, 1 H, H, Cp); 4.90 (m, 1 H, H,
Cp); 5.13 (m, 1 H, H, Cp); 5.17 (m, 1 H, H, Cp); 6.54 (s, 1 H,
CH); 7.36—7.43 (m, 3 H, Ph); 7.50 (m, 2 H, Ph). MS, m/z
(Irel (%)): 268 [M – 3 CO]+ (100), 153 (57), 114 (40). Found (%):
C, 58.01; H, 3.85; Mn, 15.6. C17H13MnNO5. Calculated (%):
C, 57.97; H, 3.72; Mn, 15.6.
Hydroxyꢀ1ꢀcymantrenylꢀ1ꢀphenylmethane. The yield was 600
1
mg (6%), m.p. 82—83 C (hexane). H NMR (acetoneꢀd6), :
4.80 (m, 1 H, H, Cp); 4.83 (m, 1 H, H, Cp); 4.96 (m, 1 H, H,
Cp); 5.02 (d, 1 H, CH, J = 4.3 Hz); 5.08 (m, 1 H, H, Cp); 5.51
(d, 1 H, OH, J = 4.6 Hz); 7.28—7.39 (m, 3 H, Ph); 7.50 (m, 2 H,
Ph). MS, m/z (Irel (%)): 226 [M – 3 CO]+ (82), 208 (35),
153 (100).
1ꢀCymantrenylphenylmethylamine. The yield was 5.4 g (52%).
1H NMR (acetoneꢀd6), : 4.79 (m, 1 H, H, Cp); 4.81 (m, 1 H,
H, Cp); 5.06 (m, 1 H, H, Cp); 5.25 (m, 1 H, H, Cp); 5.37
(s, 1 H, CH); 7.23 (t, 1 H, Ph, J = 7.3 Hz); 7.32 (t, 2 H, Ph,
J = 7.8 Hz); 7.46 (d, 2 H, Ph, J = 7.4 Hz). MS, m/z (Irel (%)):
226 [M – 3 CO]+ (83), 208 (28), 153 (100). Found (%): C, 58.41;
H, 4.11; Mn, 17.2; N, 4.42. C15H12MnNO3. Calculated (%):
C, 58.27; H, 3.91; Mn, 17.77; N, 4.53.
NꢀAcetylꢀ1ꢀcymantrenylꢀ1ꢀphenylmethylamine (6). The yield
was 1.3 g (11%), m.p. 129—130 C (hexane). 1H NMR
(acetoneꢀd6), : 1.95 (s, 3 H, Me); 4.80 (m, 1 H, H, Cp); 4.90
(m, 1 H, H, Cp); 5.04 (m, 1 H, H, Cp); 5.26 (m, 1 H, H, Cp);
5.95 (d, 1 H, CH, J = 9.2 Hz); 7.23 (t, 1 H, Ph, J = 7.3 Hz); 7.32

Dicarbonyl chelates
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
921
in 5ꢀmm tubes. IR monitoring of all the dark reactions of chelates
was carried out similarly for 72 h. The procedure irradiation—
dark reaction for 2 mM solutions of all the amides in benꢀ
zene were carried out in CaF2 cells and repeated no less
than 3 times.
(NꢀPivaloylꢀ1ꢀaminoethylcyclopentadienyl)(dicarbonyl)(triꢀ
phenylphosphine)manganese (15). A solution of compound 5
(0.35 g, 1.05 mmol) in benzene (300 mL) was placed into
a photochemical reactor and irradiated with the light of an imꢀ
mersion Hg lamp at 7 C for 30 min under argon, with the
forming CO being gradually removed. Then, PPh3 (0.45 g,
1.8 mmol) was added to the reaction mixture and it was stirred
for 4 h at 35—40 C or 12 h at ~20 C. The solvent was evaporatꢀ
ed, the product was isolated by column chromatography (benzꢀ
ene). The yield was 0.35 g (56%), m.p. 150—151 C (hexane).
1H NMR (benzeneꢀd6), : 1.37 (s, 9 H, 3 Me); 1.42 (d, 3 H, Me,
J = 6.6 Hz); 3.90 (m, 2 H, H, Cp); 4.39 (m, 1 H, H, Cp); 4.52
(m, 1 H, H, Cp); 5.37 (dq, 1 H, CH, J1 = 6.6 Hz, J2 = 8.7 Hz);
6.10 (d, 1 H, NH, J = 8.7 Hz); 7.12 (m, 10 H, PPh3); 7.66 (m, 5 H,
PPh3). 31P NMR (benzeneꢀd6), : 92.1 (s). Found (%): C, 68.07;
H, 5.84; N, 2.41; P, 5.48. C32H33MnNO3P. Calculated (%):
C, 67.96; H, 5.84; N, 2.48; P, 5.49.
5
(OꢀAcetylaminomethylꢀ ꢀcyclopentadienyl)(dicarbonyl)ꢀ
1
manganese (7). H NMR (benzeneꢀd6), : 0.80 (s, 3 H, Me);
2.68 (d, 2 H, CH2, J = 2.4 Hz); 3.15 (m, 2 H, H, Cp); 4.95 (br.t,
1 H, NH); 4.84 (m, 2 H, H, Cp). IR (benzene), /cm–1: 3403,
1930, 1857, 1650 (NC=O). UV (benzene, /nm (/L mol–1 cm–1)):
484 (517).
1ꢀ(Acetamidomethyl)cyclopentadiene (13a). 1H NMR (benzꢀ
eneꢀd6), : 1.40 (s, 3 H, Me); 2.62 (m, 2 H, CH2); 3.98 (dm, 2 H,
NCH2, J = 5.1 Hz); 4.72 (br.s, 1 H, NH); 5.86 (m, 1 H, H, Cp);
6.26 (m, 1 H, H, Cp); 6.42 (m, 1 H, H, Cp).
2ꢀ(Acetamidomethyl)cyclopentadiene (13b). 1H NMR (benzꢀ
eneꢀd6), : 1.47 (s, 3 H, Me); 2.67 (m, 2 H, CH2); 4.03 (dm, 2 H,
NCH2, J = 5.9 Hz); 4.72 (br.s, 1 H, NH); 6.07 (m, 1 H, H, Cp);
6.18 (m, 1 H, H, Cp), 6.34 (m, 1 H, H, Cp).
2
5
[1ꢀ( ꢀAllyloxy)ethylꢀ ꢀcyclopentadienyl](dicarbonyl)manꢀ
ganese (17). 1H NMR (benzeneꢀd6), , major isomer: 1.03
(d, 3 H, Me, J = 6.5 Hz); 1.73 (dm, 1 H, CH2=, J = 8.8 Hz);
2.31 (dm, 1 H, CH2=, J = 12.3 Hz); 2.77 (ddm, 1 H, CH=,
J1 = 12.3 Hz, J2 = 8.8 Hz); 2.95 (q, 1 H, CHCp, J = 6.5 Hz);
2.98 (dm, 1 H, OCH2, J = 14.7 Hz); 3.61 (m, 1 H, HCp); 3.63
(m, 1 H, HCp); 4.29 (m, 1 H, HCp); 4.33 (dm, 1 H, OCH2,
5
(OꢀBenzoylaminomethylꢀ ꢀcyclopentadienyl)(dicarbonyl)ꢀ
manganese (8). 1H NMR (benzeneꢀd6), : 2.98 (br.d, 2 H, CH2);
3.22 (m, 2 H, H, Cp); 4.97 (m, 2 H, H, Cp); 5.76 (br.t, 1 H,
NH); 6.83 (br.m, 5 H, Ph). IR (benzene), /cm–1: 3424, 1930,
1859, 1631 (NC=O). UV (benzene, /nm (/L mol–1 cm–1)):
438 (887); 533 (339).
J = 14.7 Hz); 4.71 (m, 1 H, HCp). IR (benzene), /cm–1
:
5
[1ꢀ(OꢀAcetylamino)ethylꢀ ꢀcyclopentadienyl](dicarbonyl)ꢀ
1964, 1902.
manganese (9). 1H NMR (benzeneꢀd6), : 0.71 (d, 3 H, Me,
J = 6.6 Hz); 0.84 (s, 3 H, Me); 2.93 (m, 1 H, H, Cp); 3.10 (q, 1 H,
CH, J = 6.6 Hz); 3.40 (m, 1 H, H, Cp); 4.22 (br.s, 1 H, NH);
4.83 (m, 1 H, H, Cp); 4.88 (m, 1 H, H, Cp). IR (benzene),
/cm–1: 3402, 1932, 1859, 1654 (NC=O). UV (benzene, /nm
(/L mol–1 cm–1)): 392 (146); 506 (67).
Evaluation of relative quantum yield of photolysis of comꢀ
pound 1. A 1.74 mM solution of compound 1 in THF (2.0 mL)
(328 = 1011, 365 = 356) was added to a 1.78 mM solution of [(1ꢀ
5
ꢀallyloxyꢀ2ꢀpyridꢀ2ꢀylethyl)ꢀ ꢀcyclopentadienyl](dicarbꢀ
onyl)manganese9 in THF (1.5 mL) (
= 1090, 
= 471),
328
365
and the mixture was saturated with argon. The aliquots of this
mixture with a total absorption of 0.74 (0.37 optical density for
each component) at 365 nm were placed into a IR cell (KBr,
l = 0.21 mm, S = 4.5 cm2), the cell was placed 5 cm apart from
a mercury lamp and irradiated with  = 365 nm light using
filters. A decrease in the concentration of both complexes was
determined based on the optical density of the IR bands at
2020 cm–1 ( = 8484) for amide 1 and at 1901 cm–1 ( = 8026)
5
[1ꢀ(OꢀBenzoylamino)ethylꢀ ꢀcyclopentadienyl](dicarbonꢀ
yl)manganese (10). 1H NMR (benzeneꢀd6), : 0.86 (d, 3 H, Me,
J = 6.4 Hz); 3.04 (m, 1 H, H, Cp); 3.21 (q, 1 H, CH, J = 6.4 Hz);
3.40 (m, 1 H, H, Cp); 4.94 (m, 1 H, H, Cp); 4.99 (m, 1 H, H,
Cp); 5.51 (br.s, 1 H, NH); 6.82 (m, 2 H, Ph); 6.96 (m, 3 H, Ph).
IR (benzene), /cm–1: 3424, 1930, 1859, 1632 (NC=O). UV
(benzene, /nm (/L mol–1 cm–1)): 435 (437); 532 (147).
5
5
[1ꢀ(OꢀPivaloylamino)ethylꢀ ꢀcyclopentadienyl](dicarbonꢀ
for [(1ꢀꢀallyloxyꢀ2ꢀpyridꢀ2ꢀylethyl)ꢀ ꢀcyclopentadienyl]ꢀ
yl)manganese (11). 1H NMR (benzeneꢀd6), : 0.63 (s, 9 H,
3 Me); 0.91 (d, 3 H, Me, J = 6.4 Hz); 3.06 (m, 1 H, H, Cp); 3.20
(q, 1 H, CH, J = 6.4 Hz); 3.27 (m, 1 H, H, Cp); 4.54 (br.s, 1 H,
NH); 4.98 (m, 1 H, H, Cp); 5.01 (m, 1 H, H, Cp). IR (benzꢀ
ene), /cm–1: 3445, 1929, 1857, 1628 (NC=O). UV (benzene,
/nm (/L mol–1 cm–1)): 427 (454); 493 (280).
(dicarbonyl)manganese, which do not overlap with the (CO) of
the products. It was found that for the 7—9% conversion of comꢀ
pound 1 to the corresponding chelate 6, a 5—6% h photoisomerizaꢀ
5
tion of [(1ꢀallyloxyꢀ2ꢀpyridꢀ2ꢀylethyl)ꢀ ꢀcyclopentadienyl]ꢀ
(dicarbonyl)manganese to the pyridine chelate is observed, for
which the quantum yield is 0.8.9 The evaluation of the relative
quantum yield of photolysis of 1 based on these data gives the
value 0.80.1.
DFT calculations. Quantum chemical calculations were perꢀ
formed by the Becke—Lee—Yang—Parr (B3LYP) hybrid methꢀ
od23,24 with the 6ꢀ31G* bases.25 To confirm the extreme points
on the potential energy surface, the frequencies of the normal
vibrations of molecules were calculated, using the GAUSSIANꢀ98
computer program.26
5
[1ꢀ(OꢀAcetylamino)ꢀ1ꢀphenylmethylꢀ ꢀcyclopentadienyl)]ꢀ
(dicarbonyl)manganese (12). 1H NMR (benzeneꢀd6), : 0.88 (s, 3 H,
Me); 3.02 (m, 1 H, H, Cp); 3.23 (m, 1 H, H, Cp); 4.17 (s, 1 H,
CH); 4.61 (br.s, 1 H, NH); 4.71 (m, 1 H, H, Cp); 4.93 (m, 1 H,
H, Cp); 6.90—7.20 (m, 5 H, Ph). IR (benzene), /cm–1: 3433,
1931, 1859, 1650 (NC=O). UV (benzene, /nm (/L mol–1 cm–1)):
505 (349).
1ꢀ(Acetamidoꢀ1ꢀphenylmethyl)cyclopentadiene
(14a).
1H NMR (benzeneꢀd6), : 1.47 (s, 3 H, Me); 2.61 (d, 2 H, CH2,
J = 6.6 Hz); 5.14 (br.s, 1 H, NH); 5.85 (s, 1 H, HCPh); 6.16—6.35
(m, 3 H, HCp); 7.16—7.31 (m, 5 H, Ph).
This work was financially supported by the Russian
Academy of Sciences (Program Pꢀ8 "Development of
Methodology of Organic Synthesis and Design of Comꢀ
pounds with Valuable Applied Properties") and the Diviꢀ
sion of Chemistry and Materials Science of the Russian
Academy of Sciences (Program OKhꢀ1).
2ꢀ(Acetamidoꢀ1ꢀphenylmethyl)cyclopentadiene (14b). 1H NMR
(benzeneꢀd6), : 1.47 (s, 3 H, Me); 2.69 (s, 2 H, CH2); 5.21 (br.s,
1 H, NH); 6.07 (m, 1 H, HCPh); 6.16—6.35 (m, 3 H, HCp);
7.16—7.31 (m, 5 H, Ph).

922
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
Kelbysheva et al.
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Ser. Khim., 2013, 2083].
19. E. S. Kelbysheva, L. N. Telegina, I. A. Godovikov, T. V.
Strelkova, A. F. Smol´yakov, F. M. Dolgushin, N. M. Loim,
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21. E. O. Fischer, K. Pleszke, Chem. Ber., 1958, 91, 2719.
22. A. N. Nesmeyanov, K. N. Anisimov, N. E. Kolobova, I. B.
Zlotina, Dokl. Akad. Nauk SSSR, 1964, 154, 391 [Dokl. Chem.
(Engl. Transl.), 1964].
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