Study of the Possibility of Using Salt Metathesis Reactions for the Synthesis of the Neodymium and Samarium β-Diketiminate Chalcogenide Complexes. Unexpected Reduction of Sm(III) to Sm(II)

Article abstract of DOI:10.1134/S1070328420030057

Abstract: The possibilities of the ion exchange reactions between the neodymium(III) and samarium(III) diiodo-β-diketiminate complexes [Ln(Nacnac)I₂(Тhf)₂] (Ln = Nd (I), Sm (II); Nacnac is (Formula presented.) Thf is tetrahydrofuran)

Full text of DOI:10.1134/S1070328420030057

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2020, Vol. 46, No. 4, pp. 241–250. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Koordinatsionnaya Khimiya, 2020, Vol. 46, No. 4, pp. 221–231.
Study of the Possibility of Using Salt Metathesis Reactions
for the Synthesis of the Neodymium and Samarium β-Diketiminate
Chalcogenide Complexes. Unexpected Reduction
of Sm(III) to Sm(II)
a, b
a, b
a, b
a, b,
O. A. Mironova , T. S. Sukhikh , S. N. Konchenko , and N. A. Pushkarevsky
*
a
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
b
Novosibirsk State University, Novosibirsk, Russia
*e-mail: nikolay@niic.nsc.ru
Received September 25, 2019; revised October 23, 2019; accepted October 31, 2019
Abstract—The possibilities of the ion exchange reactions between the neodymium(III) and samarium(III)
diiodo-β-diketiminate complexes [Ln(Nacnac)I (Тhf) ] (Ln
= Nd (I), Sm (II); Nacnac is
2
2
–
i
HC C
(
Me
)
N 2,6 − C H Pr
; Thf is tetrahydrofuran) and potassium mono- and dichalcogenides K Qn
2
2
{
(
6
4
2
)
}
(
Q = S, Se, Te; n = 1, 2) in Thf are studied. The ion exchange of iodide ligands by dichalcogenide ligands does
not occur under these conditions. The reaction of complex I with K Se affords the divalent samarium com-
2
plex [Sm(Nacnac)I(Thf) ] (III). The sequence of the steps leading to the formation of this complex, includ-
2
ing the reduction of the sterically hindered bis(diketiminate) complex, is proposed.
Keywords: neodymium, samarium, β-diketiminate complexes, chalcogenide complexes, sterically induced
reduction
DOI: 10.1134/S1070328420030057
INTRODUCTION
several lanthanide cations are very rare. Various bulky
polydentate ligands are used for the kinetic stabiliza-
tion of these (poly)chalcogenide complexes. A series
of the complexes with the bridging or chelating ligands
Lanthanide cations are hard Lewis acids and pre-
dominantly form complexes with O- and N-donor
ligands. The lanthanide complexes with the ligands
coordinated by the heavy chalcogen atom (for exam-
ple, mono- and polychalcogenides or chalcogenolate
anions, where chalcogen is Q = S, Se, or Te) are less
resistant, as a rule, toward hydrolysis and oxidation
2
–
Q
(Q = S, Se, Te) stabilized by the substituted cyclo-
n
pentadienide (n = 1–3 [9–12]) or formamidinate
ligands (n = 1, 2, 4 [13–15]) is known. The single
examples of the complexes with tris(pyrazolyl borate)
(
n = 1, 2, 4, 5 [16, 17]), β-diketiminate (n = 1 [18, 19]),
[
1]. Attention to these compounds is caused by their
silylamide (n = 1, 2 [20]), or amine (n = 1, 2 [21, 22])
ligands are also known. Mononuclear chalcogenide
complexes are presented by pentachalcogenides (Q =
S, Se; n = 5) stabilized by tris(pyrazolylborate) [17] or
iminoquinone [23] ligands and by the complex
physicochemical properties interesting for practical
applications, first of all, efficient IR luminescence [2].
In addition, the molecular complexes can be used as
precursors for the thermal syntheses of lanthanide
chalcogenide (nano)materials with magnetic [3–5]
and photoelectric [6] properties. According to the
+
–
[
DyI (Thf) ] [DyI S (Thf) ] (Тhf is tetrahydrofu-
2 5 2 5 2
Cambridge Structural Database (CSD) data [7], chal- ran) containing no bulky organic ligands in the coor-
–
dination sphere of dysprosium [24]. Many polynuclear
cogenolates (QR ) and complexes with diverse chal-
cogen-substituted oxo anions significantly prevail
among the known lanthanide complexes with chalco-
gen-donor ligands. The predominant number of the
complexes with diverse chalcogen-substituted oxo
anions contains sulfur donor atoms, for example, dith-
iocarbamates and dithiophosphinates [8]. Molecular
(
“cluster”) chalcogenide complexes bearing internal
mono- and dichalcogenide ligands were studied [2].
All these complexes were synthesized using the redox
reactions in which the lanthanide complex (reducing
agent) reacts with a chalcogen source (oxidant), such
as elemental chalcogen, phosphinechalcogenide
n
complexes containing chalcogenide or polychalco- (Ph
genide fragments in the coordination sphere of one or genide complex [25]. The use of other reactions,
PS, Bu
PTe), or a transition metal polychalco-
3
3
241

2
42
MIRONOVA et al.
t
which are not related to the reduction of the chalco- BuC H ; Ln = Nd, Sm) containing the inner-cavity
5
4
genide precursors, for the synthesis of lanthanide
polychalcogenide complexes was not described. The
only exception is the substitution of chloride ions in
neodymium and samarium cyclopentadienyl dichlo-
hexacoordinated selenium atom [26, 27].
The possibility for the synthesis of the samarium
and neodymium mono- and dichalcogenide com-
plexes stabilized by the bulky N,N'-bis(2,6-diisopro-
x
rides LnCp Cl in the reactions with Na Se leading to
–
2
2
5
pylphenyl)-β-diketiminate
ligand
(Nacnac ,
the formation of the unique hexanuclear complexes
Scheme 1) using the ion exchange reactions was stud-
(Cpx = η -C H , η - ied in this work.
x
2–
5
5
[
Cp Ln (μ -Se)(μ-Se ) ]
6
6
6
2 6
5
5
KH
H2
LnI3(Thf)x
HNacnac
Dipp
KNacnac
−
−KI
SmI (Thf)2
Dipp
LnQn
N
LnI (Thf)
2
2
K2Qn
n = 1, 2)
Dipp
Dipp
Dipp
Dipp
N
N
N
(
N
N
K2Se
Ln = Sm
Ln = Sm, Nd;
Q = S, Se, Te
[
Sm(Nacnac)I(Thf) ] (III)
[
Ln(Nacnac)I (Thf) ]
2
2
2
Ln = Nd (I); Sm (II)
Scheme 1.
The diketiminate ligands (L) allow one to modify
The syntheses of K Q (Q = S, Se, Te; n = 1, 2)
2 n
the substituents both at the donor nitrogen atoms and were carried out using a described procedure [31] from
in the carbon skeleton to achieve the necessary steric the elements in Тhf in the presence of naphthalene.
and electronic effects. In addition, these ligands can The solvent and naphthalene were removed by heating
act as antennas for the sensitization of luminescence of in vacuo. The procedure was modified for the thor-
lanthanide ions due to a system of conjugated bonds.
ough purification of K Se from impurities of K Se
2 2 2
and metallic potassium. A mixture of elements (K:
.766 g, 19.6 mmol; Se powder: 0.725 g, 9.18 mmol)
0
EXPERIMENTAL
and naphthalene (0.117 g, 0.913 mmol) in Тhf was
stirred in an evacuated vessel consisting of two sections
connected at a right angle and equipped with a vac-
uum stopcock with a Teflon valve. An excess of potas-
sium was taken for the deliberately complete reduction
of selenium, and the mixture was stirred for 48 h (6 h
are usually enough for the reaction completion [31]).
A solution containing potassium naphthalide was
decanted to the second section to remove a potassium
excess. Without opening the vessel, the solvent and
naphthalene were recondensed to the first section by
cooling. The suspension was stirred, the precipitate of
All procedures with easily oxidized and hydrolyzed
substances were carried out in purified argon or in
vacuo using the standard Schlenk technique and
sealed ampules. The compounds were treated and
analyses were prepared in an argon glove box. Solvents
were distilled in argon over sodium or sodium–potas-
sium alloy in the presence of benzophenone ketyl, kept
over Na–K alloy before use, and transferred by recon-
densation in vacuo. The initial complexes [Ln(Nac-
nac)I (Тhf) ] (Ln = Nd (I), Sm (II)) were synthesized
2
2
in solutions in situ without isolation by the interaction
K Se was let to settle, and the solution was poured to
2
of equimolar amounts of lanthanide iodide (NdI ∙
3
the second section. The washing procedure was
repeated until the green color of the washing solution
disappeared (determined by potassium naphthale-
3
.5Thf or SmI ) and K(Nacnac) and in the crystalline
3
state using a described procedure [28]. SmI was
2
obtained according to the method from [29]. Other
reagents (not worse than analytical grade) were used in
the commercially available form.
nide). The precipitate of K Se was dried in vacuo on
2
heating to 70°С. The yield was 1.09 g (75%). The anal-
ysis showed a sufficient purity of the product (found:
49.5% Se, calculated: 50.24% Se).
–1
IR spectra (ν, cm ) were recorded on an FT-801
An alternative synthesis of K Se was carried out
spectrometer (Simex) in KBr pellets. Elemental anal-
2
yses (C, H, and N) were performed on a Vario Micro from the elements in liquid ammonia [32]. The prod-
Cube analyzer (Elementar). Elemental analysis on Se uct was dried in vacuo without heating. The analysis
was carried out using back iodometric titration [30]. indicated the presence of one ammonia molecule
Analysis by energy dispersive X-ray (EDX) spectros- (exp. 46.3% Se, for K Se · NH calcd. 45.33% Se),
2 3
copy was carried out using a Hitachi TM 3000 micro- which is consistent with the mentioned procedure.
scope equipped with a Bruker Nano analyzer. The product was not dried in vacuo at 250°С to
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
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2020

STUDY OF THE POSSIBILITY OF USING SALT METATHESIS REACTIONS
Table 1. Reagents used for the exchange reactions, mg/mmol
243
Q = S
Q = Se
Q = Te
Reagents
n = 1
n = 2
n = 1
n = 2
n = 1
n = 2
SmI (or [Sm(Nacnac)I (Тhf) ])
191/0.360 105/0.198 276/0.519 (354/0.366) 101/0.190 (114/0.118)
3
2
2
KL
K Q
165/0.360
40/0.36
91/0.20
29/0.20
84/0.11
50/0.11
16/0.11
237/0.519
82/0.52
121/0.155
71/0.16
87/0.19
39/0.19
87/0.37
94/0.12
56/0.12
29/0.12
43/0.13
2
n
NdI ∙ 3.5Тhf (or [Nd(Nacnac)I (Тhf) ]) 164/0.211
(201/0.209) 92/0.12
54/0.12
3
2
2
KL
K Q
97/0.21
23/0.21
25/0.16
43/0.21
40/0.12
2
n
remove ammonia, because ammonia does not affect evaporated in vacuo. The IR spectra of the solid resi-
the course of further reactions.
dues were identical for each lanthanide and corre-
sponded to the spectra of complexes [Ln(Nac-
nac)I (Тhf) ] [28].
Reaction of [Ln(Nacnac)I (Тhf) ] with potassium
2
2
2
2
chalcogenides. To a mixture of SmI (276 mg,
3
–1
IR (ν, cm ; Sm complexes): 3055 w, 2960 s,
0
.519 mmol) and K(Nacnac) (237 mg, 0.52 mmol)
2
927 m, 2891 m, 2868 m, 1528 br.s, 1459 m, 1429 m,
was added Thf (5 mL), the resulting mixture was
1
394 br.s, 1359 m, 1338 w, 1313 s, 1262 s, 1167 m,
stirred for 12 h, and K Se (82 mg, 0.52 mmol) was
2
1
109 m, 1096 m, 1033 w.sh, 1012 s, 925 s, 875 m,
added to the formed red solution of compound II with
the KI precipitate. The reaction mixture was stirred
with heating (75°С) for 3 days. The dark solution was
separated from the orange precipitate by centrifuga-
tion. According to the EDX data, the ratio of the con-
tents of heavy elements in the precipitate was K : I :
Sm : Se = 31.8(6) : 16.8(10) : 5.0(4) : 18.6(11) at %.
The solution was concentrated in vacuo to a volume of
8
6
2
53 br.m, 838 m, 794 w.sh, 790 s, 757 m, 693 w, 667 w,
–1
36 w. IR (ν, cm ; Nd complexes): 3063 w, 2961 s,
929 m, 2868 s, 1515 br.s, 1462 m, 1435 s, 1382 br.s,
1
314 m, 1256 m, 1169 m, 1105 m, 1039 w.sh, 1015 s,
9
30 s, 844 br.m, 797 s, 787 w.sh, 760 w, 754 m, 720 w,
7
01 w, 631 m.
Direct synthesis of complex [Sm(Nacnac)I(Тhf)2]
1
mL. The formed oil was diluted with hexane (3 mL),
(
III). To a mixture of SmI (171 mg, 0.423 mmol) and
2
and the mixture was sealed in an evacuated two-sec-
tion L-like ampule. The ampule was placed in such a
way that the bottom section with the solution was at
K(Nacnac) (202 mg, 0.442 mmol) was added Thf
7 mL), and the resulting suspension was stirred at
(
room temperature for 2 h. The formed precipitate of
KI was separated by centrifugation. The solution was
slowly concentrated in vacuo to a volume of 0.5 mL,
which was accompanied by the crystallization of the
product as fine dark needle-like crystals. The solvent
was removed, and the crystals were washed with ether
40°С, and the upper section with a mixture of the
reaction products was kept at room temperature. The
solvent was transferred to the upper part due to the
temperature gradient, and soluble compounds were
extracted during several days and collected in the bot-
tom part of the ampule. The resulting solution was
concentrated to a small volume to form a mixture of
gray-brown needle-like crystals of complex [Sm(Nac-
(
two portions 1 mL each), and dried in vacuo. The
yield of complex III was 204 mg (60%).
nac)I(Тhf) ] (III), red crystals of complex II, and a
2
For C H N ISm
37
57
2
small amount of crystals of SmI (Thf) · 1.25Thf (IV ·
2
5
Anal. calcd., %
Found, %
C, 52.95
C, 53.8
H, 6.85
H, 7.05
N, 3.34
N, 3.5
1
.25Thf according to the X-ray structure analysis
data). The formed crystalline product was decanted
and dried in vacuo. A minor amount of the dark finely
crystalline precipitate of samarium(II) iodide (Sm : I =
According to the elemental analysis data, the com-
pound contains about 5% of a KNacnac impurity.
According to the EDX data, the ratio was Sm : I =
1
1.4(9) : 22.6(15) at % according to the EDX data)
remained in the upper part of the ampule. The inter-
action of equimolar amounts of the beforehand iso-
4
.4(8) : 3.6(5) at %.
–1
lated complex II with K Se gave the same results.
IR (ν, cm ): 3058 w, 2960 s, 2928 m, 2869 m,
624 m, 1551 s, 1489 w, 1463 m, 1436 m, 1381 m,
363 m, 1323 m, 1274 m, 1254 m, 1174 m, 1099 w,
059 w, 1022 w, 934 w, 838 w, 787 m, 759 m, 731 m,
01 m.
Reaction of SmI with K Se. A mixture of SmI
3
2
1
The reactions with other potassium chalcogenides
and with the neodymium complexes were carried out
similarly (the reagents and their amounts are indicated
in Table 1). No change in the color of the solution was
observed after heating for 3 days. After the precipitate
1
1
7
3
2
was separated by centrifugation, the solutions were (57 mg, 0.11 mol), K
Se (25 mg, 0.16 mol), and Thf
2
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
44
MIRONOVA et al.
(
2 mL) was sealed in an evacuated ampule. The
RESULTS AND DISCUSSION
ampule was kept at 45°С for 24 h (no occurrence of the
reaction was observed). Then the temperature was
increased to 70°С, and the mixture was kept for 15 h
more. The color of the solution changed from yellow
to colorless, and an orange precipitate was formed. No
further changes were induced by the prolonger storage
of the mixture at the same temperature for 20 days.
The “softest” Lewis base, iodide anion, should be
the best leaving halide in the exchange of halide
ligands by chalcogenides in the coordination sphere of
lanthanide ions. Therefore, we checked the possibility
of exchange reactions of iodide ions in the
[
(
Nd(Nacnac)I (Тhf) ] (I) and [Sm(Nacnac)I (Тhf) ]
2 2 2 2
II) complexes, whose synthesis was described earlier
Reaction of SmI with K Se . A mixture of SmI
2
2
2
3
[28]. As a rule, the formation of the KI precipitate
(
49 mg, 0.12 mol), K Se (16 mg, 0.07 mol), and Тhf insoluble in an organic solvent results in the shift of the
2
2
(
2 mL) was sealed in an evacuated ampule. The ion exchange equilibrium, which can lead to the for-
ampule was kept at 70°С for 20 days. No changes were mation of the chalcogenide complexes (Eq. (1), Solv
observed after 40 h of the reaction. Single yellow crys- denotes solvent molecules, e.g., Тhf, as ligands).
tals were formed after 5 days. Their cell parameters
LnLI2
(
Solv)m + K Q (s)
2 n
were identical to those for SmI (Тhf) (according to
3
3.5
(
1)
the X-ray diffraction data on several single crystals,
they were compared with the TOVZAF structure in
the CSD). The amount of the yellow crystals
increased within the next 15 days along with the grad-
ual bleaching of the dark blue solution (this color is
→ LnL Qn )(Solv)x + 2KI↓ (s).
(
An aprotic solvent of medium polarity is the most
optimum medium for the reaction. A weakly polar or
nonsolvating solvent would result in a very low reac-
tion rate because of an insignificant concentration of
ions in the solution. A high-polarity solvent (dimethyl
sulfoxide, dimethylformamide) or a solvent capable of
chelating (e.g., dimethoxyethane or tetramethyleth-
ylenediamine) can lead to the isolation of lanthanide
characteristic of SmI ). The brown precipitate of
2
K Se retained to the end of the experiment and the
2
2
solution was not decolorated indicating that the reac-
tion occurred incompletely.
3+
The X-ray structure analyses of compounds III
cations as solvate complexes [Ln(Solv) ] followed by
x
(
two modifications) and IV were carried out using a
the complete dissociation of the initial complexes and
the redistribution of the stabilizing ligand and chalco-
genide ligands between the cations. Protic solvents
(e.g., alcohols) can be fairly strong acids for the pro-
tonation of the stabilizing anionic ligand, resulting in
its leaving in the form of a neutral molecule. There-
fore, Тhf was chosen as a solvent capable of solvating,
to some extent, alkaline metal ions. At the same time,
Thf is a fairly labile ligand capable of leaving the coor-
dination sphere of lanthanides [28, 37, 38]. Side pro-
cesses are possible in the reactions of iodide ligand
exchange by chalcogenide ligands, such as a deeper
redistribution of ions rather than the exchange of two
iodide ions by chalcogenide. In this case, insoluble
lanthanide chalcogenides can be formed, for example,
according to Eq. (2) (here and in other reaction equa-
tions, solvate Тhf molecules are omitted).
standard procedure on a Bruker Apex DUO auto-
mated four-circle diffractometer equipped with a
CCD two-coordinate detector (MoK radiation, λ =
0
α
.71073 Å, graphite monochromator) at 150 K.
Reflection intensities were measured using ϕ- and ω-
scanning of narrow (0.5°) frames. An absorption cor-
rection was applied using the SADABS program [33].
All selected crystals of compound IV are nonmerohe-
dral twins and, therefore, the array of the data
obtained for one of them was processed taking into
account two domains with the twinning matrix
(
1 0.031 –0.123 0 –1 0 0 0 –1), BASF 0.471. An
adsorption correction was applied using the
TWINABS program (Version 2012/1). The structures
of compounds III and IV were solved by a direct
method and refined by full-matrix least squares in the
anisotropic (for non-hydrogen atoms) approximation
using a package of the SHELXT [34] and SHEXL [35]
programs in the Olex2 program shell [36]. At the last
stages of the structure refinement of compound IV,
the data in the HKLF 5 format were used. The solvate
Тhf molecules in this structure were refined in the iso-
3
LnLI + 3K Q → Ln Q
( )3 ↓
2 2 n 2 n
(2)
+
LnL I + 5KI↓ + KL.
2
This side process should form complex species with
a higher content of diketiminate ligands, for example,
+
tropic approximation. Hydrogen atoms in all struc- [LnL ] or [LnL ]. The possibility of their formation
2
3
tures were localized geometrically and refined in the can be excluded using bulky ligands L, which make the
rigid body approximation. The crystallographic data formation of bis- or tris(diketiminate) complexes
and the experimental and structure refinement details unfavorable for steric reasons. The Nacnac ligand is
are presented in Table 2.
appropriate from the viewpoint of steric effects. In
fact, the [Ln(Nacnac) ] homoleptic complexes are
The X-ray structure analysis data were deposited
2
2
+
with the Cambridge Crystallographic Data Centre known only for divalent lanthanide ions (Ln = Sm ,
2+
2+
(
CIF files CCDC nos. 1951605 (II), 1951606 (IIIa), Eu , and Yb [38–40]), whereas these complexes of
and 1951607 (IIIb); http://www.ccdc.cam.ac.uk/ trivalent lanthanide ions with noticeably smaller ionic
conts/retrieving.html). radii (by ~0.2 Å [41]) are poorly stable because of steric
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
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STUDY OF THE POSSIBILITY OF USING SALT METATHESIS REACTIONS
245
Table 2. Crystallographic data and structure refinement results for compounds III and IV
Value
Parameter
IIIa
IIIb
IV · 1.25Thf
Empirical formula
C H N O ISm
C H N O ISm
C H O I Sm
3
7
57
2
2
37 57
2
2
25 50 6.25 2
FW
Space group
a, Å
b, Å
c, Å
α, deg
β, deg
γ, deg
839.09
839.09
P1
854.80
P1
P2 /n
1
8.8354(6)
39.068(2)
22.3398(14)
90
98.594(2)
90
624.7(8)
8.5558(7)
18.8555(16)
23.909(2)
88.869(3)
80.891(3)
86.627(3)
3801.7(6)
13.0752(10)
22.7268(17)
23.9186(18)
69.185(3)
84.109(3)
89.264(3)
6606.5(9)
V, Å3
7
Z
8
4
8
ρcalc, g/cm3
μ, mm–1
1
.462
.381
3392.0
1.466
1.719
2
2.388
3.679
F(000)
1696.0
3344.0
Crystal size, mm
Range of data collection over 2θ,
0.26 × 0.13 × 0.05
2.118–51.478
0.33 × 0.05 × 0.05
1.726–49.426
0.31 × 0.28 × 0.12
1.83–51.462
deg
Ranges h, k, l
–10 ≤ h ≤ 10,
–10 ≤ h ≤ 7,
–22 ≤ k ≤ 22,
–28 ≤ l ≤ 28
–15 ≤ h ≤ 15,
–27 ≤ k ≤ 27,
–29 ≤ l ≤ 29
–
37 ≤ k ≤ 47,
27 ≤ l ≤ 26
–
Number of measured reflections
68526
28301
40003
Number of independent
14478 (0.0578, 0.0593)
12767 (0.0641, 0.1119)
40003 (0.0523, 0.0745)
reflections (R , R )
int
σ
Number of refined parameters
Number of restraints
947
594
884
242
1086
665
GOOF for F 2
1.039
0.946
1.099
R factor (I > 2σ(I))
R = 0.0441,
R = 0.0464,
R = 0.0593,
1
1
1
wR = 0.0775
wR = 0.0688
wR = 0.1184
2
2
2
R factor (all data)
R = 0.0751,
R = 0.0981,
R = 0.1076,
1
1
1
wR = 0.0855
wR = 0.0822
wR = 0.1455
2
2
2
Δρmax/Δρmin, e Å–3
1.36/–0.81
0.72/–0.73
3.15/–2.18
III
+
factors. The only known complex [Tm (Nacnac) ]
tion to occur if the Gibbs energies of formation of the
lanthanide iodide and chalcogenide complexes in
solutions differ by a lower value. No data on the Gibbs
energies of formation are available for other potassium
2
was isolated only in the presence of the noncoordinat-
–
ing anion [B(C F ) ] [42].
6
5 4
An additional hindrance for the ion exchange reac-
tion is the low solubility of the initial chalcogenides
K Q in moderately polar organic solvents, which can
level down the driving force of the ion exchange reac-
tion. Nevertheless, it can be estimated that the forma-
(
di)chalcogenides K Q (n = 1, 2; Q = S, Se, Te) and,
2 n
hence, this gain cannot be estimated directly. How-
ever, the gain can be expected to be even higher due to
the expectedly lower enthalpies of formation of other
K Q compared to that of K S.
2
n
2
n
2
°
298
tion of two moles of KI (Δ G = –324.9 kJ/mol)
f
The reagents were stirred in Thf at room tempera-
from one mole of K S (Δ G = –364.0 kJ/mol [43]) ture in order to study the possibility of substitution
°
2
f
298
provides a substantial thermodynamic gain of reactions to occur. The concentration of the starting
2
85.8 kJ. This can be enough for the substitution reac- lanthanide complex in solution was about 0.02 mol/L.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
46
MIRONOVA et al.
In all cases, no reaction was observed within 8 h of stir- (Table 3). The coordination environment of the
ring. Then the temperature was increased to 60°С, and samarium atom represents a tetragonal pyramid with a
–
after 72-h stirring the solution was separated and evap- base formed by two nitrogen atoms of the Nacnac
orated in vacuo. The IR spectrum of the solute was ligand and two oxygen atoms of the Тhf molecules
compared with the known spectrum of β-diketiminate (Fig. 1a), and the iodine atom is located at the pyra-
diiodide complex I or II. It has previously been mid vertex. The coordination number is equal to five,
shown [28] that the absorption bands corresponding which is unusually low compared to that of complex II
to vibrations of the conjugated system of the β-dike- (coordination number 6), in spite of the larger size of
timinate ligand are very sensitive to the ligand environ-
ment in the complex. By analogy to the known scan-
dium β-diketiminate chalcogenide complexes [18,
2+
3+
the Sm cation compared to that of Sm . Only one
II
similar ytterbium complex [Yb (Nacnac)(μ-I)(Thf)]
2
(
coordination number 5) is known among the lantha-
1
9], we believe that the reaction products of the
2+
nide(II) compounds [44]. The Yb ion is coordinated
by two iodide ions and only one Тhf molecule,
although the complex crystallizes from this solvent.
exchange of iodide ions by (di)chalcogenides should
be fairly soluble in Тhf, and the presence of them
would change the vibration frequencies in the IR spec-
trum. However, in all cases except for the reaction of
2
+
Since the ionic radius of Yb is noticeably smaller
2+
than that for Sm (1.08 and 1.22 Å, respectively, for
coordination number 7 [41]), it can be concluded that
the Тhf molecule occupies a larger volume in the coor-
dination sphere than the iodide anion. In both crystal-
line modifications IIIa and IIIb, the molecules are
oriented similarly relative to the nearest neighbors and
the iodine atom of one complex is arranged between
the cycles of two Тhf molecules of the adjacent com-
plex (Fig. 1b). The stacks are thus formed which
propargate along the [100] direction. The adjacent
complex II with K Se, the IR spectra of the com-
2
pounds isolated from solutions did not differ from that
for the initial complex I or II. Thus, even a prolonged
contact of the reactants at elevated temperature does
not result in the formation of molecular chalcogenide
complexes.
The color of the reaction mixture changed from
light yellow to brown in the only case of the reaction of
complex I with K Se for 24 h (60°С). Black needle-
2
II
like crystals of the complex [Sm (Nacnac)I(Thf) ] molecules in the stacks are shifted by the translation
III) were isolated from the solution in 72 h. This vector, which determines the minimal lattice parame-
2
(
compound is formed in a yield of ~15% and crystal- ter a (in both cases, see Table 3). Two modifications
lizes along with the unreacted initial complex II. A differ by the relative turn of the adjacent stacks. The
longer reaction time results in the gradual disappear- diketiminate ligand in the complex adopts the charac-
ance of complex II from the solution. However, the teristic “boat” geometry, and the C(1), C(3), N(1),
crystallization of III is accompanied, in this case, by and N(2) atoms lie almost in one plane. The C(2)
the formation of an insoluble by-product of undeter- atom deviates from the least-squares plane of these
mined structure from can be removed by recrystalliza- atoms by 0.120–0.144 Å, and the samarium atom devi-
tion from a Thf-hexane (1 : 5 vol/vol) mixture. We ates in the same direction by 0.958 and 0.961 Å or by
failed to attain a noticeable increase in the yield of 1.084 and 1.114 Å, depending on the modification
compound III. The formation of III in the bulk was (atom numbering given in Fig. 1a). The Sm–I, Sm–
proved by the X-ray diffraction analysis of the single N, and Sm–O bond lengths are nearly the same for
crystal, and the same cell parameters were confirmed two modifications, and the bonds are substantially
for several crystals taken from the mixture of visually elongated compared to similar bonds in complex II
homogeneous crystalline precipitates obtained in (Table 2), which unambiguously confirms the oxida-
independent experiments. The ratio of the amounts of tion state of samarium +2 in complex III. A compari-
the heavy atoms Sm : I = 1 : 1 was confirmed by the son of the IR spectra of complexes II and III is also
EDX method. For a more complete characterization, remarkable. The characteristic frequencies of vibra-
complex III was synthesized via the direct reaction of tions of the conjugated system of bonds in β-diketimi-
samarium diiodide SmI (Тhf) with one equivalent of nate are sensitive to a different ligand environment.
2
2
K(Nacnac).
According to the earlier studies [28], the spectrum of
the Sm(III) β-diketiminate complex exhibits the char-
acteristic bands corresponding to stretching vibrations
Two polymorphic modifications IIIa and IIIb were
obtained by the crystallization of complex III obtained
in the reaction of II with K Se and by direct reaction.
The crystallization conditions differed so that IIIa
was crystallized by the evaporation of a Тhf
solution, whereas IIIb was crystallized from a Тhf–
hexane (1 : 5 vol/vol) mixture. Nevertheless, both
modifications contain no solvate molecules. Each
of the C=C, C=N, and C‒CH bonds in the ligand
3
2
–1
(
1528, 1398, 1314, 1166, and 924 cm ) and to the C–
–1
O bond vibrations in coordinated Тhf (853 cm ). The
spectrum of complex III demonstrates appreciable
shifts of the bands of the diketiminate ligand to the
–1
high-energy range, except for the peak at 1398 cm
–1
structure contains two crystallographically indepen- (1551, 1381, 1324, 1174, and 934 cm ), and the peak of
–1
dent molecules, and the molecular structures of the coordinated Тhf is observed at 840 cm . The spec-
complexes are nearly identical in both modifications trum also exhibits the medium-intensity band at
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
Vol. 46
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STUDY OF THE POSSIBILITY OF USING SALT METATHESIS REACTIONS
Table 3. Selected bond lengths (Å) in complexes II [28] and IIIa
247
IIb
Bond
Sm–N(1)
Sm–N(2)
Sm–O(1)
Sm–O(2)
Sm–I
IIIa (IIIb)
c
c
2.400(3)
2.536(3)
2
2
2
2
3
.514(4), 2.507(4) (2.523(5), 2.514(5) )
c
c
.515(4), 2.519(4) (2.522(5), 2.521(5) )
c
c
.552(4), 2.546(4) (2.571(4), 2.544(4) )
c
c
.559(1), 2.557(4) (2.570(4), 2.587(5) )
c
c
3.0823(5), 3.0072(4)
.1536(5), 3.1582(5) (3.1554(6), 3.1577(7) )
a
b
c
Atoms are enumerated according to Fig. 1.
The molecule of the complex lies on the crystallographic symmetry plane passing through the Sm and I atoms.
Data for the second independent molecule.
622 cm–1 corresponding to the formation of small excess potassium. The selenium content in the
1
amounts of HNacnac due to hydrolysis during spec- obtained K
Se samples well corresponded to the theo-
2
trum recording.
retical value, and the admissible residual amounts of
free potassium could not result in the formation of
noticeable amounts of the reduction product of III.
Therefore, the influence of an elemental potassium
impurity can be excluded.
The formation of the Sm(II) complex from
Sm(III) in the reaction that occurs in the absence of
evident strong reducing agents is a fairly unusual fact,
since all Sm(II) compounds are strong reducing
+
3+
2+
The transformation of Sm into Sm can also
take place as a result of so-called sterically induced
agents (for example, E° for the SmI SmI pair in Тhf
2
2
+
is 1.41 V vs. Fc /Fc [45]). It can be assumed that the reduction [46]. In these processes, one of the anionic
reducing agent in the reaction is metallic potassium, ligands donates an electron and leaves as a neutral par-
which could remain in the K Se sample after its syn-
–
*
2
2
ticle (e.g., Cp* – e → Cp*· → 0.5Cp , Cp* is pen-
thesis from the elements. To exclude this possibility, tamethylcyclopentadiene). The leaving ligand is sub-
K Se was synthesized by different methods using liq- stituted by a less bulky one, or the lanthanide ion is
2
uid ammonia as a reaction medium or Тhf with naph- reduced accompanied by an increase in the ionic
3
+
2+
thalene as an electron carrier. In both cases, the radius (Ln → Ln ). Any variant leads to a decrease
absence of coloration of the final solutions was thor- in the steric hindrance in the coordination sphere. A
oughly monitored that would indicate an admixture of higher steric hindrance of the coordination
(а)
(b)
(c)
b
c
I(2)
a
I
O(2)
C
C(3)
C(1)
O
N(2)
Sm
Sm
C(2)
O(1)
N(1)
C
I
N
Sm
O
I(1)
Fig. 1. (a) Molecular structure of complex III according to the X-ray structure data, (b) crystal packing of molecules of complex
III, and (c) molecular structure of complex IV according to the X-ray structure data. Thermal ellipsoids are given with 50% prob-
ability, hydrogen atoms are omitted, and organic fragments are presented in the simplified form.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
48
MIRONOVA et al.
sphere results in the situation where the reduction plex to Sm(II) accompanied by leaving of one iodide
process becomes more favorable. For the complexes ligand and samarium(III) selenide formation. The
with β-diketiminate ligands, a similar reduction effect formation in the reaction the solid phase containing
of the ligand was described for complexes of euro- samarium and selenium in significant and comparable
pium, which is characterized by the highest potential amounts was shown by the EDX method. This overall
3+
2+
of Ln /Ln among all lanthanides [37, 47]. The process (possible reaction is described by Eq. (7)) will
Me –
also result in the formation of the [Sm(Nacnac) ]
reaction of EuCl with a less bulky anion (L )
2
3
Me
complex, assuming that the diketiminate ligands are
stable under the reaction conditions.
III
Me
affords complex [Eu L ] (L
=
{N(2-
3
MeC H )C(Me)} CH), whereas the presence of a
6
4
2
Me2 –
more bulky anion (L
)
leads to the sterically
( )
Sm Nacnac I + Red
[
2]
Nacnac)2 + Red–I,
(5)
induced reduction of europium and formation of
→
[
Sm
(
]
II
Me2
Me2
[
(
Eu (L ) (Тhf)] (L
= {N(2,6-Me C H )C-
2 6 3
2
Me)} CH). It should be mentioned that only one
2
[
Sm
(
(
Nacnac 2 + Sm(Nacnac)I
)
]
2
3+
example of sterically induced reduction of Sm to
(6)
(7)
→
Sm Nacnac I + Sm Nacnac I,
)
[
(
)2
]
2+
Sm
is known. This reduction occurred
upon an attempt to insert three very bulky and rigid
6
S m
(
N a c n a c
)
I + 7 K S e
BIG
5
2
2
pentaphenylcyclopentadienyl ligands (Cp
= η -
t
3+
→ Sm Se + 2Sm
(
)
Nacnac I
C (4- BuC H )) into the coordination sphere of Sm
2
3
5
6
4
[
[
48]. As a result, the stable sandwich complex
+ 2 Sm Nacnac)2 + 10KI + 2K Se .
[
(
]
2 2
BIG
2
II
Sm Cp ] is formed, stabilized by interaction of the
The possibility of the ligand redistribution between
the Sm(II) complexes is indicated by the fact that
minor amounts of samarium diiodide (insoluble under
these conditions) were formed upon the recrystalliza-
phenyl rings of the adjacent cycles. A similar reduction
process in the studied reaction would require the inter-
mediate formation of a sterically hindered complex.
+
This complex can be [Sm(Nacnac) ] , which could be tion of separately obtained complex III from hexane.
2
formed in the ligand disproportionation process In some cases, individual crystals of this compound
(
Eq. (3)). The latter can be driven by the simultaneous were also isolated from a Тhf solution after the reac-
formation of insoluble samarium selenide (Eq. (4)). In tion of complex II with K Se. Probably, the solubility
2
fact, it is shown in a separate experiment that the reac- of the [Sm(Nacnac) ] complex is much higher, which
2
tion of SmI with K Se in Тhf gradually leads to the
3
2
prevents its crystallization.
complete precipitation of samarium in the form of
Sm Se .
Two reducing agents are possible in the studied sys-
tem: selenide and diketiminate anions. Under the dis-
cussed reaction conditions, their reduction potentials
are unknown, but the possibility of the redox process
to occur can be evaluated using the known reactions as
references. For example, the possibility of the reduc-
tion of elemental selenium by samarium(II) iodide
2
3
2
Sm
(
Nacnac
Sm
Sm Se + 2 Sm Nacnac I + 6KI.
)
I2 →
[
Sm
(
Nacnac)2
]
I + SmI , (3)
3
4
(
Nacnac
)
I + 3K Se
2
2
(4)
→
[
(
)2
]
2
3
+
A similar thulium complex [Tm(Nacnac) ] was
2−
2–
2
with the formation of Se or Se , depending on the
2
shown [42] to be very unstable, and one of the ligands
readily loses the proton of the methyl group of the
main chain in the presence of bases to form the heter-
oligand complex [Tm(Nacnac)(Nacnac')] (Nacnac' is
stoichiometry of the reducing agent, was demon-
strated [49]. A SmI excess is needed for the complete
2
2–
reduction to Se , but the reaction does not proceed to
the end even in this case. The completeness of the
reaction can be provided only by the addition of
hexamethylphosphatriamide, which increases the
2–
CH(C(CH )NDipp)(C(=CH )NDipp) ).
Since
3
2
K Se can play the role of a base, a similar transforma-
2
tion in the studied reaction can be expected. However,
the deprotonation of the ligand should result in the
retention of the Sm(III) complex rather than in metal
reduction. In addition, [Sm(Nacnac)(Nacnac')] was
not found in the reaction mixture. Another probable
reduction potential of SmI in a Thf solution. Our
2
experiment showed that the reaction of SmI with
2
K Se in Thf occurred very slowly at elevated tempera-
2
2
tures (at 70°С the incomplete occurrence of the reac-
tion becomes noticeable within ~15 days). Thus, we
may conclude that the redox potential of K Se /K Se
+
route of [Sm(Nacnac) ] transformation can be the
2
II
2
2
2
reduction to the neutral complex [Sm (Nacnac) ]
2
+
2
is close to that of SmI /SmI in Тhf and K Se can be
(
Eq. (5), Red is reducing agent), which is stable under
2
2
the reducing agent in this reaction. On the contrary,
the reaction conditions [39]. It can be assumed that
–
the initial complex III is formed due to one more pro- we believe that the Nacnac anion cannot act as a
cess of ligand exchange under the reaction conditions reducing agent in this process, since otherwise the ini-
(
Eq. (6)). Thus, the overall process (Eqs. (4)–(6)) can tial [Sm(Nacnac)I (Тhf) ] complex can undergo the
2 2
be represented as the reduction of the Sm(III) com- intramolecular redox process leading to the formation
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
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2020

STUDY OF THE POSSIBILITY OF USING SALT METATHESIS REACTIONS
249
of Sm(II) compounds, which is not observed even on complexes with (poly)chalcogenide anions in the
prolonged heating of solutions of this complex during coordination sphere. It is most likely that the best syn-
recrystallization [28]. In addition, the one-electron thetic method for these complexes is provided by the
–
oxidation of the Nacnac anion should afford the reactions involving redox transformations [18, 19].
dimeric product (Nacnac) [50], but the characteristic According to the proposed scheme of the reaction of
2
complex II with K Se, the samarium complexes with
signals of this compound are absent in the NMR spec-
2
tra of the reaction solution. It is most likely that the N-donor ligands can also participate in the sterically
role of the diketiminate ligand is to provide the neces- induced reduction processes, which have been known
3+
so far mainly for the cyclopentadienyl derivatives. The
possibility of the variation of the steric influence of the
N-donor ligands in the coordination sphere of samar-
ium can potentially lead to the further development of
the chemistry of the redox processes involving the
complexes of this element.
sary steric hindrance of the Sm ion, because SmI is
3
not reduced in the absence of the diketiminate ligand
under other equivalent conditions.
The scheme proposed for the process agrees with
the absence of the reaction for the neodymium com-
plexes, since the reduction potential of neodymium is
much higher than that of samarium [51]. It is not quite
clear why complex II does not react with other potas-
FUNDING
sium (di)chalcogenides except for K Se. In these
2
This work was supported by the Russian Science Foun-
dation, project no. 16-13-10294.
cases, the observed absence of redox processes can be
explained by (a) a low solubility of potassium chalco-
genides under the experimental conditions, which
decreases the driving force and reaction rate, and (b)
an insufficiently high reduction potential of some
CONFLICT OF INTEREST
2–
2–
The authors declare that they have no conflicts of
interest.
chalcogenides compared to that of Se (e.g., S or
2
2
−
Se ). Nevertheless, it cannot be excluded that the
reduction reactions can also occur with other chalco-
genides but with a lower rate.
REFERENCES
Crystals of samarium(II) iodide formed in minor
amounts were studied by X-ray structure analysis. The
structure contains molecular complexes [SmI (Тhf) ]
1. Atwood, D.A., Platt, S.M., Cotton, S.A., Harrow-
field, J.M., et al., The Rare Earth Elements: Funda-
mentals and Applications, Chichester: Wiley, 2012.
2. Brennan, J.G., in The Rare Earth Elements: Fundamen-
tals and Applications, Atwood, D.A., Ed., Chichester:
Wiley, 2012, p. 215.
2
5
and 1.25 molecules of solvate Тhf per samarium atom.
The complex is characterized by a nearly regular pen-
tagonal bipyramidal structure in which the Тhf mole-
cules are arranged in the equatorial plane (Fig. 1c).
The unit cell contains four independent molecules of
the complex with similar geometric parameters (the
bond lengths are Sm–I 3.227(2)–3.266(2) and Sm–O
3. Kataoka, T., Tsukahara, Y., Hasegawa, Y., and
Wada, Y., Chem. Commun., 2005, no. 48, p. 6038.
4. Kar, S., Boncher, W.L., Olszewski, D., et al., J. Am.
Chem. Soc., 2010, vol. 132, no. 40, p. 13960.
2
.546(11)–2.630(10) Å). Note that attempts to deter-
5
6
7
. Selinsky, R.S., Han, J.H., Pe, E.A.M., and Guzei, I.A.,
mine the structure of SmI (Тhf) · nТhf were made
J. Am. Chem. Soc., 2010, vol. 132, no. 21, p. 15997.
2
5
previously [52], but the authors succeeded to localize
only the heavy Sm and I atoms and to determine the
geometry of the complex because of the low quality of
the obtained structural data. The R factor was 15%,
. Ghosh, A.B., Saha, N., Sarkar, A., et al., RSC Adv.,
2015, vol. 5, no. 124, p. 102818.
. Groom, C.R., Bruno, I.J., Lightfoot, M.P., and Ward,
S.C., Acta Crystallogr., Sect. B: Struct. Sci., Cryst. Eng.
Mater., 2016, vol. 72, p. 171.
space group P2 /n, unit cell parameters a = 23.154(12),
1
b = 26.033(6), c = 23.866(10) Å, β = 111.69(4)°, V =
8. Zhou, J., Coord. Chem. Rev., 2016, vol. 315, p. 112.
3
1
3367(11) Å , Z = 16. The exact number of solvate
9
. Evans, W.J., Rabe, G.W., Ziller, J.W., and Doedens,
molecules were not determined earlier either. The
structure of the obtained crystals of SmI (Тhf) ·
.25Тhf was solved in the cell with a halved volume as
R.J., Inorg. Chem., 1994, vol. 33, no. 2, p. 2719.
2
5
1
0. Fieser, M.E., Johnson, C.W., Bates, E., et al., Organo-
1
metallics, 2015, no. 34, p. 4387.
a nonmerohedral twin in the space group P1 (Z = 8).
Both the coordinated and solvate Thf molecules were
reliably localized. Unfortunately, the coordinates of
the atoms are not presented in the previous article [52]
and in the corresponding CSD file (ZEKXIW) and,
hence, it remains unclear whether these compounds
are identical in fact or they represent different phases.
1
1. Evans, W.J., Rabe, G.W., Ansari, A., and Ziller, J.W.,
Angew. Chem., 1994, vol. 859, no. 3, p. 3.
1
2. Evans, W.J., Davis, B.L., Champagne, T.M., and Zill-
er, J.W., Proc. Natl. Acad. Sci. U. S. A., 2006, vol. 103,
no. 34, p. 12678.
13. Zhou, A.X., Hong, J., Tian, H., and Zhang, L., Angew.
Chem., Int. Ed. Engl., 2017, vol. 57, no. 4, p. 1062.
Thus, the ion exchange reactions cannot be applied 14. Werner, D., Zhao, X., Best, S.P., et al., Chem.-Eur. J.,
to the synthesis of the lanthanide β-diketiminates
2017, vol. 23, no. 9, p. 2084.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 46 No. 4 2020

2
50
MIRONOVA et al.
1
5. Ma, Y.Z., Bestgen, S., Gamer, M.T., et al., Angew. 33. APEX2 (version 2.0). SAINT (version 8.18c), and
Chem., Int. Ed., 2017, vol. 56, no. 43, p. 13249.
6. Kühling, M., McDonald, R., Liebing, P., Hilfert, L.,
et al., Dalt. Trans., 2016, vol. 45, no. 25, p. 10118.
SADABS (version 2.11), Madison: Bruker Advanced X-
ray Solutions, 2000–2012.
1
3
3
3
4. Sheldrick, G.M., Acta Crystallogr., Sect. A: Found. Adv.,
2015, vol. 71, no. 1, p. 3.
17. Zhang, F., Zhang, J., and Zhou, X., Inorg. Chem., 2017,
5. Sheldrick, G.M., Acta Crystallogr., Sect. C: Struct.
vol. 56, no. 4, p. 2070.
Chem., 2015, vol. 71, no. 1, p. 3.
18. Maron, A.L., Han, X., Xiang, L., et al., Chem.-Eur. J.,
6. Dolomanov, O.V., Bourhis, L.J., Gildea, R.J., How-
ard, J.A.K., et al., J. Appl. Crystallogr., 2009, vol. 42,
no. 2, p. 339.
2017, vol. 23, no. 59, p. 14728.
19. Knight, L.K., Piers, W.E., and McDonald, R., Chem.-
Eur. J., 2000, vol. 6, no. 23, p. 4322.
3
7. Evans, W.J., Hughes, L.A., and Hanusa, T.P., J. Am.
20. Corbey, J.F., Fang, M., Ziller, J.W., and Evans, W.J.,
Chem. Soc., 1984, vol. 106, no. 15, p. 4270.
Inorg. Chem., 2014, vol. 53, no. 6, p. 3099.
38. Harder, S., Angew. Chem., Int. Ed, 2004, vol. 43, no. 20,
p. 2714.
21. Kornienko, A.Y., Emge, T.J., and Brennan, J.G., J.
Am. Chem. Soc., 2001, vol. 123, no. 48, p. 11933.
39. Shen, X., Zhang, Y., Xue, M., and Shen, Q., Dalton
Trans., 2012, vol. 41, no. 13, p. 3668.
22. Huebner, L., Kornienko, A., Emge, T.J., and
Brennan, J.G., Inorg. Chem., 2005, vol. 44, no. 14, 40. Xue, M., Zheng, Y., Hong, Y., Yao, Y., et al., Dalton
p. 5118.
Trans., 2015, vol. 44, no. 46, p. 20075.
4
1. Shannon, R.D., Acta Crystallogr., Sect. A: Cryst. Phys.,
23. Coughlin, E.J., Zeller, M., and Bart, S.C., Angew.
Chem., Int. Ed. Engl., 2017, vol. 56, no. 40, p. 12142.
Diffr., Theor. Gen. Crystallogr., 1976, vol. 32, p. 751.
4
2. Hitchcock, P.B., Lappert, M.F., and Protchenko, A.V.,
2
4. Fagin, A.A., Kuznetsova, O.V., Balashova, T.V., Cher-
kasov, A.V., et al., Inorg. Chim. Acta, 2018, vol. 469,
p. 227.
Chem. Commun., 2005, vol. 301, no. 7, p. 951.
4
4
4
4
3. Lide, D.L., CRC Handbook of Chemistry and Physics,
Boca Raton: CRC Press, 2004.
2
5. Afonin, M.Y., Sukhikh, T.S., Konokhova, A.Y., and
Konchenko, S.N., Russ. J. Coord. Chem., 2018, vol. 44,
no. 2, p. 147.
4. Hitchcock, P.B., Khvostov, A.V., Lappert, M.F., and
Protchenko, A.V., J. Chem. Soc., 2009, no. 13, p. 2383.
5. Enemærke, R.J., Daasbjerg, K., and Skrydstrup, T.,
https://doi.org/10.1134/S107032841802001X
Chem. Commun., 1999, no. 4, p. 343.
2
2
2
2
3
6. Jin, G.-X., Cheng, Y., and Lin, Y., Organometallics,
6. Evans, W.J. and Davis, B.L., Chem. Rev., 2002,
2002, vol. 18, no. 6, p. 947.
vol. 102, no. 6, p. 2119.
7. Cheng, Y., Jin, G.-X., Shen, Q., and Lin, Y., J. Or-
ganomet. Chem., 2001, vol. 631, p. 94.
8. Mironova, O.A., Sukhikh, T.S., Konchenko, S.N., and
4
7. Jiao, R., Shen, X., Xue, M., Zhang, Y., et al., Chem.
Commun., 2010, vol. 46, no. 23, p. 4118.
4
8. Ruspic, C., Moss, J.R., Schurmann, M., and
Harder, S., Angew. Chem., Int. Ed. Engl., 2008, vol. 47,
no. 11, p. 2121.
Pushkarevsky, N.A., Polyhedron, 2019, vol. 159, p. 337.
9. Wayda, A.L., Cheng, S., and Mukerji, I., J. Organomet.
Chem., 1987, vol. 330, p. C17.
0. Yarembash, E.I. and Eliseev, A.A., Khalkogenidy red-
4
9. Sekiguchi, M., Tanaka, H., Takami, N., Ogawa, A.,
et al., Heteroat. Chem., 1991, vol. 2, no. 3, p. 427.
kozemel'nykh elementov: Sintez i Kristallokhimiya (Hal- 50. Shimokawa, C. and Itoh, S., Inorg. Chem., 2005,
cogenides of Rare Earth Elements: Synthesis and Crys-
tal Structure). Moscow: Nauka, 1975.
vol. 44, no. 9, p. 3010.
1. Morss, L.R., Chem. Rev., 1976, vol. 76, no. 6, p. 827.
5
31. Thompson, D.P. and Boudjouk, P., Org. Chem., 1988, 52. Evans, W.J., Gummersheimer, T.S., and Ziller, J.W., J.
vol. 53, no. 9, p. 2109.
Am. Chem. Soc., 1995, vol. 117, no. 35, p. 8999.
3
2. Mossbauer, F. and Lss, O., Inorg. Chem., 1991, vol. 30,
no. 11, p. 2540.
Translated by E. Yablonskaya
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
Vol. 46
No. 4
2020