Crystal Structures and Characteristics of Hirshfeld Surfaces of Co(II) β-Iminoketonate Derivatives

Article abstract of DOI:10.1134/S0022476619070059

A series of Co β-iminoketonate derivatives with the general formula Co(L¹)₂, (L¹ = i-acac (R = H, R¹ = R² = Me) – (1), Mei-acac (R = R¹ = R² = Me) – (2), i-thd (R = H, R¹ = R² = ^tBu) – (3), Mei-thd (R = Me, R¹ = R² = ^tBu) – (4)) and Co(L²) (L²= dmpda(acac)₂ – (5) are obtained by the reaction of CoCl₂ with the sodium salt of the corresponding β-iminoketonate ligand (L¹ = R¹C(O)CHC(NR)CR² or L² = MeC(O)CHC(Me)(NCH₂C(Me)2CH₂N)C(Me)CHC(O)Me) in methanol. Complexes 1-5 are characterized by the methods of elemental analysis, X-ray diffraction, and IR spectroscopy. The crystal cell parameters at 293 K are as follows: space group Сс, a = 13.7304(9) ?, b = 5.5516(4) ?, с = 18.4034(12) ?, β = 101.964(2)°, V = 1372.34(16) ?³, Z = 4 (2); space group P2₁/n, a = 9.953(2) ?, b = 12.074(3) ?, с = 11.161(2) ?, β = 109.924(8)°, V = 1260.9(5) ?³, Z = 2 (3); space group P1?, a = 11.7982(7) ?, b = 13.1673(9) ?, с = 17.6159(10) ?, α = 71.493(2)°, β = 83.478(2)°, γ = 72.829(2)°, V = 2478.7(3) ?³, Z = 4 (4); space group Pbca, a = 7.8635(2) ?, b = 14.0521(4) ?, с = 29.8715(9) ?, V = 3300.76(16) ?³, Z = 8 (5). Two pairs of shortened contacts are revealed in molecules 2 and 5 when studying their Hirshfeld surfaces. It is shown with the thermogravimetry method that complexes 1 and 2 are the most volatile in the studied series.

Full text of DOI:10.1134/S0022476619070059

ISSN 0022-4766, Journal of Structural Chemistry, 2019, Vol. 60, No. 7, pp. 1052-1061. © Pleiades Publishing, Inc., 2019.
Russian Text © The Author(s), 2019, published in Zhurnal Strukturnoi Khimii, 2019, Vol. 60, No. 7, pp. 1100-1109.
CRYSTAL STRUCTURES AND CHARACTERISTICS
OF HIRSHFELD SURFACES OF Сo(II)
β- IMINOKETONATE DERIVATIVES
1,2 1,2
S. I. Dorovskikh *, D. A. Piryazev ,
1
P. A. Stabnikov , and N. B. Morozova
1
1 1
A series of Co β-iminoketonate derivatives with the general formula Co(L ) , (L = i-acac (R = H,
2
1
2
1
2
1
2
R = R = Me) – (1), Mei-acac (R = R = R = Me) – (2), i-thd (R = H, R = R = Bu) – (3), Mei-thd
t
1
2
t
2
2
(
2 2
R = Me, R = R = Bu) – (4)) and Co(L ) (L = dmpda(acac) – (5) are obtained by the reaction of CoCl
1
with the sodium salt of the corresponding β-iminoketonate ligand (L = R C(O)CHC(NR)CR or
1
2
2
L = MeC(O)CHC(Me)(NCH C(Me) CH N)C(Me)CHC(O)Me) in methanol. Complexes 1-5 are
2
2
2
characterized by the methods of elemental analysis, X-ray diffraction, and IR spectroscopy. The crystal cell
parameters at 293 K are as follows: space group Сс, a = 13.7304(9) Å, b = 5.5516(4) Å, с = 18.4034(12) Å,
3
1
β = 101.964(2)°, V = 1372.34(16) Å , Z = 4 (2); space group P2 /n, a = 9.953(2) Å, b = 12.074(3) Å,
3
с = 11.161(2) Å, β = 109.924(8)°, V = 1260.9(5) Å , Z = 2 (3); space group P1, a = 11.7982(7) Å,
3
b = 13.1673(9) Å, с = 17.6159(10) Å, α = 71.493(2)°, β = 83.478(2)°, γ = 72.829(2)°, V = 2478.7(3) Å ,
3
Z = 4 (4); space group Pbca, a = 7.8635(2) Å, b = 14.0521(4) Å, с = 29.8715(9) Å, V = 3300.76(16) Å ,
Z = 8 (5). Two pairs of shortened contacts are revealed in molecules 2 and 5 when studying their Hirshfeld
surfaces. It is shown with the thermogravimetry method that complexes 1 and 2 are the most volatile in the
studied series.
DOI: 10.1134/S0022476619070059
Keywords: cobalt, XRD, β-iminoketonate complexes, Hirshfeld surface.
INTRODUCTION
Cobalt-containing nanoparticles and thin films are widely used as photocatalysts [1-4], electrodes for
supercapacitors [5, 6], magnetic layers in MRAM memory cells [7, 8]. Recent studies on the problem of H
course of photoelectrochemical decomposition of water [9] demonstrate the potentiality of using the Co
2
generation in the
3
O /FTO (fluorine
4
doped TiO
containing layer on the photocatalytic activity of the anode during water decomposition is currently an important problem
10-12]. Co layers are commonly prepared using such methods as sol–gel [13], sputtering [14], electrodeposition [15]. Of
2 3 4
) film system as an anode material. Studying the influence of the structure and morphology of the Сo O
[
3 4
O
special interest is the method of chemical vapor deposition (MOCVD) and its analogue atomic layer deposition (ALD) to
1
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia;
2
ciaemon@gmail.com. Novosibirsk State University, Novosibirsk, Russia. Original article submitted December 27, 2018;
*
revised February 5, 2019; accepted February 5, 2019.
1052
0022-4766/19/6007-1052 © 2019 by Pleiades Publishing, Ltd.

deposit functional layers with specific characteristics on the substrates of various shapes and sizes at relatively low
temperatures [16, 17]. There are currently several known examples of preparing Co /FTO and F-Co /TiO film systems
3
O
4
3
O
4
2
by MOCVD/ALD methods using precursors such as Co(II, III) β-diketonate or β-iminoketonate derivatives [18-20].
The volatile compound (precursor) is a key element of MOCVD/ALD processes to determine the characteristics of
the formed layer. Temperature parameters of the MOCVD/ALD process and the type of the reagent gas are determined from
the thermal properties of the precursor [21]. On the other hand, its thermal behavior can be estimated by analyzing its
structure and intermolecular interactions. Correlations between structural characteristics and thermal properties provides the
possibility of a rational choice of precursors to optimize the process of depositing layers with desired characteristics.
Complexes of Co(II) with β-iminoketonates are among promising precursors for the deposition of nanoparticles and
thin films [20, 23]. To date, only a few representatives of this class have been prepared and characterized, including the series
Сo(PhC(O)CHC(NR)Me)
Сo(MeC(O)CHC(NR)Me)
complexes, aromatic complexes Сo(PhC(O)CHC(NR)Me)
2
(R = phenyl- or aryl substituted groups) [22], Сo(CF
3
C(O)CHC(NCH
2
CF
O Pr) [20]. Among these
are low volatile due to high molecular weight, while
3 3 2
)CF ) [23], and
i
i
2
2 2 2 2 2 3 2 3 2 3
(R = Pr, (CH ) OMe, (CH ) OEt, (CH ) OMe, (CH ) OEt, (CH )
2
Сo(MeC(O)CHC(NR)Me)
Сo(MeC(O)CHC(NR)Me)
2
2
are used in deposition processes [20]. In this regard, a study aimed at expanding the series of
precursors for MOCVD/ALD is of interest.
The paper presents the data on crystal structures of Сo(II) complexes with β-iminoketonate ligands
1
1
2
2
2 2 2
(L = R C(O)CHC(NR)CR or L = MeC(O)CHC(Me)(NCH C(Me) CH N)C(Me)CHC(O)Me) with the general formula
1
Co(L )
1
1
2
1
2
1
2
t
2
(L = i-acac (R = H, R = R = Me) – 1; Mei-acac (R = R = R = Me) – 2; i-thd (R = H, R = R = Bu) – 3; Mei-thd
1
R = Me, R = R = Bu) – 4 and Co(L ) (L = dmpda(acac)
2
t
2
2
(
2
– 5) in comparison with their closest analogues
Сo(MeC(O)CHC(NR)Me)
2
. The thermal behavior of the complexes in the condensed phase was investigated.
EXPERIMENTAL
β-Iminoketone compounds H-i-acac, HMe-i-acac, and H dmpda(acac)
2
2
were prepared by the interaction of Hacac
3 3
0.10 mol, 10 mL, ρ = 1 g/cm ) with a 25% solution of NH (0.11 mol, 10 mL, ρ = 0.77 g/cm ) and with a 50% solution of
(
3
3
3
2 3 2 2 2 2 2
NH CH (0.11 mol, 10 mL, ρ = 0.7 g/cm ), NH CH C(Me) CH NH (0.10 mol, 1 mL, ρ = 0.89 g/cm ) in 30 mL of toluene,
respectively [24]. After being kept at 0 °С, the compounds were purified by extraction from a water/chloroform mixture.
Their yield after the purification was 50-70%. For (Hi-acac), calculated (wt.%): C 60.5, H 9.4, N 14.3, found: C 60.6, H 9.3,
N 14.3, t
0 °C. For H
β-Iminoketone compounds H-i-tmhd and H-Me-i-thd were obtained in an inert atmosphere in the course of Hthd
amination (0.06 mol, 11 mL) in the presence of TiCl (0.04 mol, 3.35 g) by excess gaseous NH or NH CH , respectively
m
= 43-44 °C. For (HMei-acac), calculated (wt.%): C 64.3, H 8.9, N 12.6, found: C 64.7, H 9.2, N 12.3, t
m
= 39-
4
2
dmpda(acac) , calculated (wt.%): C 67.6, H 9.8, N 10.5, found: C 67.4, H 9.8, N 10.7, t = 86-88 °C.
2
m
4
3
2
3
[25]. The reactions were carried out until the solutions bleached. The precipitates were washed with benzene and decantated.
The compounds were purified by recrystallization from heptane. The yield of compounds after purification was 80% for
H-i-tmhd and 50% for H-Me-i-thd. For Hi-tmhd, calculated (wt.%): C 72.1, H 11.6, N 7.6, found: C 72.4, H 11.2, N 7.2,
t
m
= 131-132 °C. For H-Me-i-thd, calculated (wt.%): C 71.3, H 12.5, N 7.6, found: C 71.7, H 12.8, N 7.4, t
m
= 76-77 °C.
The synthesis of complexes 1-5 was performed by the interaction of a СoCl solution (0.030 mol, 4.04 g) in
2
methanol (60 mL) with the corresponding ligand (0.030 mol) in the presence of Na (0.027 mol, 0.621 g). Methanol was
–2
evaporated in a nitrogen flow for 24 h. The target products were purified by the method of zone sublimation (10 Torr) at
1
40-160 °С, 180-190 °С, 100-110 °С for 1-2, 3, and 4-5, respectively. The yield of the complexes after purification was 40-85%.
Elemental analysis (wt.%): for C10 Co (1), calculated: C 47.4, H 5.6, N 11.1, found: C 47.2, H 5.6, N 11.0;
Co (2), calculated: C 50.9, H. 7.1, N 8.9, found: C 51.0, H 7.5, N 8.5; for C22 Co (3) calculated:
Co (4), calculated: C 63.8, H 9.7, N 6.2, found: C 63.9,
Co (5), calculated: C 55.3, H 7.3, N 8.4, found: C 55.7, H 7.5, N 8.6.
14 2 2
H O N
for C12
H
20
O
2
N
2
40 2 2
H O N
C 62.4, H 9.5, N 6.7, found: C 62.1, H 9.1, N 6.3; for C24
H 9.5, N 6.1; for C15
44 2 2
H O N
24 2 2
H O N
1053

–1 –1
The IR spectra of 1 and 3 contain the bands of υ(N–H) stretchings at 3283 cm and 3355 cm , respectively, the
–1
spectra of 1-5 contain υ(С–H) stretchings at 3050-2800 cm ; these bands are most intense in compounds 3 and 4. The bands
–1
in the region 1585-1450 cm may be assigned to υ(С=O + С–С + С=N). Narrow bands in the range of 1390-1330 cm
–1
–1
correspond to υ(С–С) + δ(СH
3
) vibrations, which are most intense in iminoketonate spectra. The region 1300-1200 cm
–1
contains υ(С–N) stretchings, and the region 1200-800 cm is formed mainly by bending vibrations. Vibrations υ(Сo–O) and
–1
υ(Co–N) appear at 650-400 cm . The obtained data are in good agreement with IR spectroscopy data available for similar Cu
and Ni chelates [26].
1 2
Research methods. The analysis of HL , H L , and 1-5 for C, N, H was carried out on a Carlo-Erba 1108 analyzer
2
in the analytical laboratory of the Institute of Inorganic Chemistry SB RAS [27, 28]. The values obtained from three parallel
–1
samples were averaged. The IR spectra of the complexes in the region of 4000-400 cm were recorded on a Vertex 80 FTIR
–1
spectrometer (with a resolution of 1 cm ). The spectra were recorded in a fluorinated oil. Thermal analysis was performed on
a NetzschTG 209 F1 Iris thermal analyzer, the experiments were performed in a helium atmosphere (30.0 mL/min, open
Al O
2
3
crucible, 10 deg/min), the batch mass was 15-18 mg.
X-ray diffraction (XRD) of crystals 2-5, which were prepared by vacuum zone sublimation, was performed by
a standard procedure on an automatic four-axis Bruker APEX DUO diffractometer equipped with a CCD area detector, at
a temperature of 293 K, using molybdenum radiation (λ = 0.71073 Å) and a graphite monochromator. Reflection intensities
were measured by ϕ scanning of narrow (0.5°) frames. The absorption was corrected semi-empirically using the SADABS
program [29]. The structures were determined by the direct method and refined by the full-matrix least-squares method in the
anisotropic approximation using the SHELXTL program package [30]. Hydrogen atoms were refined in a rigid body
t
approximation. In structure 3, the Bu group in the cis- position relative to the nitrogen atom of the ligand is disordered over
two positions with the fractions of 0.57 and 0.43. Table 1 lists detailed XRD data and the main crystal structure data for
2
-5. CIF files containing complete information on the studied structures were deposited with the CCDC under the numbers
577785, 1577784, 1577788, and 1577786 for 2, 3, 4, and 5, respectively (www.ccdc.cam.ac.uk/data_reguest/cif).
The Hirshfeld surfaces (HSs) were calculated and analyzed using the CrystalExplorer17 software package [30] with
1
an implemented Tonto program for electron density calculations [31]. Spherical electron density was calculated using Koga–
Kanayama–Watanabe–Imai–Thakkar wave functions [32]. The initial lengths of the bonds with participation of hydrogen
atoms were taken equal to the bond lengths determined in neutron diffraction studies. The HSs were constructed using high
resolution with a weight factor of 0.5.
RESULTS AND DISCUSSION
1
2
2
The structures of complexes 2-5 are composed of neutral isolated molecules Co(L ) or Co(L ) (Fig. 1), structure 4
consists of two crystallographically independent molecules. The coordination environment of cobalt is formed by ligand
atoms: two O and two N. As far as the coordination of the central atom, complexes 2-5 can be separated into square (3) and
distorted tetrahedral (2, 4, and 5) structures. This type of coordination significantly affects the values of chelate lengths and
angles. For the goal of comparison, Table 2 summarizes main values of bond lengths and angles in the studied complexes and
in their analogues Co β-iminoketonates [20, 22, 23].
The largest differences in the series 2-5 are observed for Со–O and Со–N bonds. The lengths of Со–O and Со–N
chelate bonds are 1.838(3) Å and 1.864(3) Å for 3, and 1.9037(18)-1.9274(10) Å and 1.9649(11)-1.9776(19) Å for 2, 4, 5,
respectively. Со–N distances in the complexes exceed Со–O distances by the average value of ∼0.03-0.06 Å; this difference
is most pronounced for the complexes with branched terminal substituents (4) or substituents at the nitrogen atom in (5) and
2 3 2 3 3 2
Сo(MeC(O)CHC(N′)Me) [20], Сo(CF C(O)CHC(NCH CF )CF ) [23]. The lengths of C–C bonds in the metallocycle are
1054

TABLE 1. X-Ray Data on the Studied Co(II) Complexes
Structural formula
Empirical formula
Molecular weight
Temperature, K
Crystal family
Space group
a, Å
Co(Mei-acac)
2
(2)
Co(i-thd)
2
(3)
Co(Mei-thd)
2
(4)
Co[(dmpda)(acac)
2
] (5)
C
12
H
20CoN O
2
2
C
22
H
40CoN O
2
2
C
24
H
44CoN O
2
2
15 30 2 2
C H N O
Co
283.23
293(2)
423.49
293(2)
Monoclinic
P2 /n
451.54
293(2)
329.34
293(2)
Monoclinic
C2/c
Triclinic
P1
Orthorhombic
Pbca
1
13.7304(9)
5.5516(4)
9.953(2)
12.074(3)
11.161(2)
11.7982(7)
13.1673(9)
7.8635(2)
14.0521(4)
29.8715(9)
–, 90, –
b, Å
c, Å
18.4034(12)
17.6149(10)
α, β, γ, deg
–, 101.964(2), –
–, 109.924(8), – 71.493(2), 3.478(2),
.829(2)
2
3
V, Å
1372.34(16)
4
1260.9(5)
2
2478.7(3)
3300.76(16)
8
Z
4
1.210
–
3
ρ
calc, g/cm
1.371
1.115
0.697
1.325
–
1
μ, mm
Crystal size, mm
θ range, deg
Miller indices range
1.243
1.043
0.31×0.28×0.25
0.35×0.23×0.20
0.19×0.17×0.14
0.23×0.17×0.15
2
4.52-61.38
4.74-52.78
2.44-52.94
5.454-53.078
–16 ≤ h ≤ 19,
–12 ≤ h ≤ 12,
–13 ≤ k ≤ 15,
–13 ≤ l ≤ 13
11372 / 124
2563
–14 ≤ h ≤ 14,
–16 ≤ k ≤ 16,
–22 ≤ l ≤ 14
22875 / 551
10198
–9 ≤ h ≤ 9,
–17 ≤ k ≤ 17,
–37 ≤ l ≤ 37
37277 / 187
3405
–7 ≤ k ≤ 6,
–
26 ≤ l ≤ 21
7515 / 81
2127
N
refl. / Nparam.
indep.refl.
int
N
R
0.0121
0.0340
0.0204
0.0281
2
Goodness-of-fit on F
1.213
1.098
1.047
1.452
R1 / wR2 (I ≥ 2σ(I ))
R1 / wR2 (all data)
0.0268 / 0.0673
0.0274 / 0.0675
0.62 / –0.59
0.0645 / 0.1842
0.0434 / 0.1142
0.0491 / 0.1737
0.0698 / 0.1895
0.94 / –0.47
0.0562 / 0.1226
1.32 / –0.32
0.0562 / 0.1813
0.32 / –0.99
Max/min residual
3
peak of electron density, e/Å
also sensitive to the substituent type at the nitrogen atom. In the series 2-5, the difference between the lengths of C–C bonds
in the chelate cycle is 0.045-0.082 Å, the maximum value is observed for 5. Interestingly, the six-membered metallocycle in 5
with a fragment of 2,2-dimethylpropylene diamine has a twist-boat conformation (intermediate between chair and boat
conformations). The ∠OCoN chelate angles in 2-5 range from 95.79(8) to 97.30(7)°. In all Co(II) β-iminoketonate
complexes, the metal cycles have inflection angles (λ) along the О…N line; the largest λ values in the series 2-5 are observed
for 4 and 5. The degree of tetrahedricity of the complexes is expressed by the rotation angle of chelate cycles Ψ which falls
into the interval 65.5-89.5°. The largest deviation from the perfect tetrahedricity takes place in molecule 5. In contrast to
other studied structures, molecules 3 have a square environment of the central atom, and the angle between the chelate cycles
is 0° due to the fact that the central Co atom occurs in the center of inversion. There are two 2.83 Å long agostic contacts
Co1…H3A inside molecule 2.
Fig. 2 presents Hirshfeld surfaces of 2-5 as maps of a dimensionless function dnorm [33], where negative values
(corresponding to shortened intermolecular contacts) are shown red and positive values are shown blue. Area (S), volume (V),
sphericity (G), asphericity (Ω) [34] were calculated for each HS. The corresponding values are listed in Table 3
1055

Fig. 1. Crystal structures of Co(II) β-iminoketonates: 2 (a), 4 (b), 5 (c), 6 (d).
Sphericity (the measure of how closely the surface area approaches that of a sphere with the same volume) for
Co(II) complexes falls within the range of 0.717-0.789. The relative difference is 12%, with the lowest value observed for
compound 3 with a flat-square coordination of the central atom. At the same time, the asphericity parameter that characterizes
the anisotropy of the complexes is more sensitive to the coordination type of the central atom. For 3, this parameter is 0.095
and varies within 0.068-0.078 in the series of tetrahedral complexes.
The HSs of molecules 2 and 5 demonstrate two pairs of shortened contacts O…H–С (3.27 Å, 3.44 Å and 3.55 Å,
3.62 Å, respectively) involving hydrogen atoms of methyl groups, corresponding to weak hydrogen bonds (Fig. 2a, d). The
molecules in structure 2 constitute a distorted hexagonal packing (isolated island type). Structure 2 contains corrugated layers
arranged perpendicular to the c axis (Fig. 3a). The Co…Co distance between the layers is с/2 (9.23 Å). The Co–Co–Co
angles in the layer are 112° and 136°. In contrast to 2, the packing of molecules in 5 is pseudohexagonal and is formed by
layers perpendicular to the b axis (Fig. 3d). The Co…Co distances in the layer are 8.779 Å, 7.374 Å, and 7.864 Å, and the
t
CoCoCo angles are 137.35°, 106.04°, and 113.97°. In the flat-square complex 3, the Bu substituents of neighboring
molecules are oriented towards the fifth and sixth coordination sites of cobalt to form short Co…H contacts (reaching
t
2
.954 Å in one of the sites, while the distance from the cobalt atom to the quaternary carbon of the Bu group is 4.343 Å)
Fig. 2b). The presence of these contacts determines a pseudo-layered (herringbone) packing of molecules 3 in crystals. The
shortest Co…Co distances between the neighboring complexes are 8.569 Å (Fig. 3b). A pair of shortened Co…H–C contacts
3.83 Å) and a pair of N…H–C contacts (3.67 Å) is also observed in 4 (Fig. 2c). Molecules 4 in crystals form a hexagonal
(
(
isolated island packing with layers, each layer containing both independent molecules. The planes of the layers are normal to
the [011] direction (Fig. 3c). The CoCoCo angles in the layers are 143°, 128°, and 86°. The neighboring molecules in
different layers form even stacks with Co…Co distances of 8.98 Å and 9.36 Å and the CoCoCo angle of 178°.
1056

TABLE 2. Main Stereochemical Characteristics of Co(II) β-Iminoketonates
Formula
Co–O, Å
Co–N, Å
∠O(N)CoO(N), deg
λ, deg
Ψ, deg
CSD code
2
1.927(1)
1.838(3)
1.965(1)
1.864(3)
96.41(4)
92.7(1)
3.9
87.0
0
1
1
1
1
577785
3
0.3
577784
4
1.915(2);
1.921(2);
1.904(2);
1.922(2)
1.91(2);
1.920(5)
1.920(1);
1.934(1)
1.931
1.970(2);
1.974(2)
1.967(2);
1.969(2)
1.997(6);
1.997(8)
1.964(2)
1.970(2)
1.985
97.22(7);
97.30(7)
3.1-10.2
9.4-10.5
75.6
65.5
70.6
86.8
85.9
80.0
84.2
89.5
86.7
81.1
83.7
79.5
65.5-89.5
577788
5
95.79(8)-95.95(11)
577786
Сo(CF
3
C(O)CHC(NCH
NACPEM [23]
Сo(PhC(O)CHC(NpTol)Me)
WAYKUE [22]
2
CF
3
)CF
3 2
)
96.1(7);
96.3(3)
96.41(6);
96.57(6)
95.13
3.2;
10.1
2
3.1; 5.3
Сo(PhC(O)CHC(NAr1)Me)
WAYLAL [22]
2
16.5
15.3
Сo(PhC(O)CHC(NAr2)Me)
WAYLEP [22]
2
1.910
1.946
95.98
Сo(PhC(O)CHC(NAr3)Me)
WAYLIT [22]
2
1.907(2);
1.915(2)
1.927(2);
1.931(2)
1.914(3);
1.917(3)
1.964(2)
1.965(2)
1.963(3);
1.963(7)
1.951(3);
1.958(3)
95.81(7);
97.29(7)
95.9(1);
96.7(1)
2.7; 4.5
4.6; 10.6
3.3; 6.8
6-15
Сo(PhC(O)CHC(NAr4)Me)
WAYLOZ [22]
2
Сo(PhC(O)CHC(N Ph)Me)
2
96.3(1);
97.2(1)
WAYLUF [22]
i
Сo(MeC(O)CHC(N Pr)Me)
2
〈1.933(3)〉 〈1.985(3)〉
〈1.923(2)〉 〈1.980(1)〉
〈1.934(1)〉 〈1.988(2)〉
〈97.7(1)〉
1
587793 [20]
Сo(MeC(O)CHC(N(CH
587794 [20]
Сo(MeC(O)CHC(N(CH
587795 [20]
Range
2
)
2
OMe)Me)
2
〈95.9(1)〉
〈96.3(3)〉
1
2 2 2
) OEt)Me)
1
1.907(2)–
.934(1)
1.951(1)–
1.997(6)
95.79(8)-97.30(7)
0.3-16.5
1
*
pTol – о-tolyl, Ar1 – п-methoxyphenyl, Ar2 – о-dimethylphenyl, Ar3 – m-dimethylphenyl, Ar4 – п-
trifluorophenyl.
i
The crystal packing is sensitive to the variation of substituents at the nitrogen atom. Сo(MeC(O)CHC(N Pr)Me)
2
[20] and Сo(СF COCHC(NСH CF )СF ) [23] form hexagonal packings (isolated island packing), if branched alkyl or
3 2 3 3 2
fluoroalkyl substituents of molecules 2, 4 are introduced; a pseudo-layered (herringbone (3)) packing is formed in the
absence of substituents; and pseudo-dimeric and layered packings prevail when aromatic groups and closed aliphatic (5) and
methoxy groups are introduced [20, 22].
m
Thermal properties. The melting points (t , °C) of the complexes are 172-173 (1), 175-176 (2), 232-233 (3), 147-
148 (4), 149-152 (5). Interestingly, the introduction of a methyl substituent usually decreases the melting point, since the type
of molecular packing in crystals is changed. Indeed, in the case of the derivatives (complexes 3 and 4), the introduction of
1057

Fig. 2. Hirshfeld surfaces of Co(II) β-iminoketonates: 2 (a), 4 (b), 5 (c), 6 (d).
TABLE 3. Shape Characteristics of Hirshfeld Surfaces of Co(II) Complexes
3
2
Complex
V, Å
S, Å
G
Ω
2
3
4
336.29
622.17
608.55
310.74
491.50
478.51
481.70
336.02
0.753
0.717
0.726
0.726
0.789
0.078
0.095
0.070
0.068
0.070
614.77
5
405.85
1058

Fig. 3. Packings of Co(II) β-iminoketonate molecules in crystals: 2 (a), 4 (b), 5 (c), 6 (d).
a methyl substituent leads to a decrease in the melting point by ∼80 °С. However, acac derivatives (complexes 1 and 2)
showed no significant differences, probably due to the presence of intramolecular agostic contacts in structure 2 (for
i
2
Сo(MeC(O)CHC(N Pr)Me) , tm. = 163-164 °C [20]).
In the conditions of the thermogravimetric experiment, 2 and 3 almost quantitatively transform into the gas phase
the weight loss is 98-99%), while 1 and 4, 5 are partially decomposed (the weight loss is 89-93%) (Fig. 4). The weight loss
(
begins at 90-150 °С and ends at 210-240 °С for most volatile compounds 1, 2, and 4, and begins at 200 °С and ends at 260-
275 °С for compounds 3 and 5.
Fig. 4. Curves of Co(II) β-iminoketonate weight loss.
1059

Qualitatively, the volatility series of 1-5 (t50% weight loss, °C) is as follows: 2 (196) > 1 (205) > 4 (219) > 3
245) > 5 (263). A similar volatility series was obtained previously for Ni, Cu β-iminoketonates [31, 35] to indicate that the
(
metal atom does not significantly affect the thermal behavior of complexes when heated under the conditions of
a thermographic (TG) experiment.
2 2
The volatilities of complexes 1-5 with Сo(MeC(O)CHC(NR′)Me) (5 deg/min, N 300 mL/min) [20] cannot be
compared due to different conditions of TG experiments. The data reported in [20] indicate that Сo(MeC(O)CHC(NR)Me)2
transforms into the gas phase almost quantitatively in the temperature range of 50-320 °С. The introduction of alkoxy groups
i
(
R = (CH
2 2 2 2 2 3 2 3 2 3
) OMe, (CH ) OEt, (CH ) OMe, (CH ) OEt, (CH ) O Pr) leads to a lower volatility than in the case of
i
Сo(MeC(O)CHC(N Pr)Me)
2
. Thus, the comparison of TG data for 1-5 and Сo(MeC(O)CHC(NR)Me)
2
indicates that the
volatility of cobalt β-iminoketonates is increased in the presence of alkyl groups at the donor nitrogen atom, which is largely
due to the fact that the type of molecular packing changes from layered or pseudodimeric (3 and 5) to isolated island (2 and 4).
MAIN RESULTS AND CONCLUSIONS
A series of cobalt β-iminoketonate (acetylacetonate and tetramethylheptanedionate) derivatives were obtained and
characterized by the methods of elemental analysis and IR spectroscopy, their structures were first determined. Depending on
the presence of a substituent at the donor nitrogen atom, the structures of the complexes constitute a tetrahedral and (in the
absence of a substituent) a flat-square coordination environment of the metal ion. Using the Hirshfeld method for the analysis
the surfaces of the molecules of the complexes, it was shown that the asphericity parameter is most sensitive to the
coordination type of the central atom: 0.095 for the complex with a square geometry and 0.068-0.078 for tetrahedral
complexes. When studying Hirshfeld surfaces of β-iminoketonate molecules, O…H–С, O…H–N and Co…H–С interactions
were discovered. It was shown that the volatility of the complexes is increased in the presence of alkyl groups at the donor
nitrogen atom, which is largely due to the fact that the type of molecular packing of β-iminoketonates changes from the
layered or the pseudodimeric (in the absence of a substituent at the donor nitrogen atom) to the isolated island (in the
presence of methyl groups at the donor nitrogen atom).
CONFLICT OF INTERESTS
The authors declare that they have no conflict of interests.
REFERENCES
1
2
3
4
. D. K. Nandi, J. Manna, A. Dhara, P. Sharma, and S. K. Sarkar. J. Vaс. Sci. Technol. A, 2016, 34(1), 01A115.
. X. Xie,Y. Li, Z.Q. Liu, M. Haruta, and W. Shen. Nature, 2009, 458(7239), 746.
. C. Y. Ma, Z. Mu, J. J. Li, Y. G. Jin, J. Cheng, G. Q. Lu, and S. Z. Qiao. J. Amer. Chem. Soc., 2010, 132(8), 2608.
. S. Zafeiratos, T. Dintzer, D. Teschner, R. Blume, M. Hävecker, A. Knop-Gericke, and R. Schlögl. Catalysis, 2010,
269(2), 309.
5
6
7
8
9
. V. R. Shinde, S. B. Mahadik, T. P. Gujar, and C. D. Lokhande. Appl. Surf. Sci., 2006, 252(20), 7487.
. A. D. Jagadale, V. S. Kumbhar, and C. D. Lokhande. J. Colloid Interface Sci., 2013, 406, 225.
. S. A. Makhlouf, Z. H. Bakr, K. I. Aly, and M. S. Moustafa. Superlattices Microstruct., 2013, 64, 107.
. S. A. Yousaf, M. Ikram, and S. Ali. Appl. Nanosci., 2018, 1.
. M. Ebadi, M. A. Mat-Teridi, M. Y. Sulaiman, W. J. Basirun, N. Asim, N. A. Ludin, M. A. Ibrahim, and K. Sopian. RSC
Adv., 2015, 5, 36820.
10. E. Arciga-Duran, Y. Meas, J. J. Pérez-Bueno, J. C. Ballesteros, and G. Trejo. J. Electrochem. Soc., 2018, 165(4),
H3178.
1060

11. L. Gao, J. Diwu, Q. Zhang, H. Xu, X. Chou, J. Tang, and C. Xue. J. Nanomater., 2015, 2015, 6.
12. G. A. Kaptagay, T. M. Inerbaev, Y. A. Mastrikov, E. A. Kotomin, and A. T. Akilbekov. Solid State Ionics, 2015, 277,
77.
1
1
1
3. V. Patil, P. Joshi, M. Chougule, and S. Sen. Soft Nanosci. Lett., 2012, 2, 1.
4. M. Patel, M. Kumar, H. S. Kim, W. H. Park, E. H. Choi, and J. Kim. Mater. Sci. Semicond. Process., 2018, 74, 74.
5. T. Yoshino, B. A. Nobuyoshi, and K. Yamaga. In: Adv. Materials′93 / Eds. H. Aoki, X. Miao and et.al. Elsevier:
Amsterdam, 1994, 371–395.
16. K. E. K. Holden, M. A. Jenkins, and J. F. Conley. ECS Trans., 2018, 85(13), 735.
17. S. Jung, D. K. Nandi, S.Yeo, H. Kim, Y. Jang, J. S. Bae, and S. H. Kim. Surf. Coat. Technol., 2018, 337, 404.
18. M. E. Donders, H. C. Knoops, M. Kessels, and P. H. L. Notten. J. Electrochem. Soc., 2011, 158(4), G92.
19. A. Gasparotto, D. Barreca, D. Bekermann, A. Devi, R. A. Fischer, P. Fornasiero, and G. Van Tendeloo. J. Am. Chem.
Soc., 2011, 133(48), 19362.
20. K. Junge Puring, D. Zywitzki, D. H. Taffa, D. Rogalla, M. Winter, M. Wark, and A. Devi. Inorg. Chem., 2018, 57(9),
5133.
2
1. I. K. Igumenov, T. V. Basova, and V. R. Belosludov. In: Application of Thermodynamics to Biological and Material
Science / Eds. T. Mizutani. InTech: Rijeka, 2011, 521–546.
22. A. L. Rheingold and M. B. Allen. CSD Communication. №NACPEM, 1996.
23. K. C. D. Robson, C. D. Phillips, B. O. Patrick, and W. S. McNeil. Dalton Trans., 2010, 39, 2573.
2
4. I. A. Baidina, P. A. Stabnikov, A. D. Vasiliev, S. A. Gromilov, and I. K. Igumenov. J. Strust. Chem., 2004, 45, 671–767.
5. P. A. Stabnikov, G. I. Zharkova, I. A. Baidina, S. V. Tkachev, V. V. Krisyuk, and I. K. Igumenov. Polyhedron, 2007,
6, 4445.
2
2
2
2
2
2
6. P. A. Stabnikov. Rus. J. Gen. Chem., 2013, 83(10), 1919–1927.
7. V. P. Fadeeva and I. M. Moryakina. Russ. Chem. Bull., 1981, 6, 113.
8. V. P. Fadeeva,V. D. Tikhova, and O. N. Nikulicheva. J. Anal. Chem., 2008, 63, 1094.
9. Bruker AXS Inc. (2004). APEX2 (Version 1.08), SAINT (Version 7.03), and SADABS (Version 2.11). Bruker
Advanced X-ray Solutions, Madison, Wisconsin, USA.
30. G. M. Sheldrick. Acta Crystallogr., 2008, A64(1), 112.
3
1. M. J. Turner, J. J. McKinnon, S. K. Wolff, D. J. Grimwood, P. R. Spackman, D. Jayatilaka, and M. A. Spackman.
CrystalExploreR17. University of Western Australia, 2017. http://hirshfeldsurface.net
2. D. Jayatilaka and D. J. Grimwood Tonto. Computational Science – ICCS, 2003, 4, 142.
3. M. A. Spackman and D. Jayatilaka. Cryst. Eng. Comm., 2009, 11(1), 19.
4. J. J. McKinnon, D. Jayatilaka, and M. A. Spackman. Chem. Commun., 2007, 37, 3814.
5. G. I. Zharkova, S. I. Dorovskikh, S. V. Sysoev, I. P. Asanov, A. V. Panin, N. B. Morozova, and I. K. Igumenov. Surf.
Coat. Technol., 2013, 230, 290.
3
3
3
3
1061