Influence of the Aromatic Ligand Nature and Synthesis Conditions on the Structures of the Copper Pentafluorobenzoate Complexes

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ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2023, Vol. 49, No. 4, pp. 230–246. © Pleiades Publishing, Ltd., 2023.
Russian Text © The Author(s), 2023, published in Koordinatsionnaya Khimiya, 2023, Vol. 49, No. 4, pp. 299–245.
Influence of the Aromatic Ligand Nature and Synthesis Conditions
on the Structures of the Copper Pentafluorobenzoate Complexes
V. V. Kovaleva, M. A. Shmeleva, *, G. N. Kuznetsovaa, †, V. I. Erakhtinab, G. A. Razgonyaevaa,
T. M. Iva nov aa, M. A. Kiskina, A. A. Sidorova, and I. L. Eremenkoa
a Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
b School no. 1449 named after Hero of the Soviet Union M.V. Vodop’yanov, Moscow, Russia
*е-mail: shmelevma@yandex.ru
Received November 23, 2022; revised January 11, 2023; accepted January 12, 2023
Abstract—New pentafluorobenzoate (Рfb) copper complexes with 2,3- and 3,5-lutidine (2,3- and 3,5-Lut,
respectively), quinoline (Quin), and 1,10-phenanthroline (Рhen) ([Cu2(MeCN)2(Рfb)4] (I), [Cu(2,3-
Lut)2(Pfb)2] (II), [Cu(3,5-Lut)4(Pf b)2] (III), [Cu(Quin)2(Pfb)2] (IV), and [Cu2(Phen)2(Pfb)4] (V)) are syn-
thesized by the newly developed methods and characterized. The unusual heteroanionic pentafluorobenzo-
ate benzoate (Вnz) ionic compound [Cu2(Рhen)2(Рfb)3]+(Рnz)– (VI) is synthesized. It is shown that the
four-bridge binuclear metal cage of complex I is not retained in the reactions with various pyridine deriva-
tives. In the case of such α-substituted pyridines as 2,3-lutidine and quinoline, the compositions and struc-
tures of the final products of the reactions with copper pentafluorobenzoate are independent of the initial
ratio of the reagents and crystallization conditions. It is revealed by the Hirshfeld surface analysis that π···π,
C–F···π, C–H···F, and F···F interactions make the major contribution to the stabilization of crystal packings
of the synthesized complexes.
Keywords: copper pentafluorobenzoates, heteroanionic complexes, noncovalent interactions, Hirshfeld sur-
face
DOI: 10.1134/S1070328422600619
INTRODUCTION
Many investigations oriented to the preparation of
functional materials are based on the studies of new
approaches to the target synthesis of polynuclear coor-
dination compounds of specified compositions and
structures [1–5]. The development of new efficient
methodologies is a necessary condition for the search
for coordination compounds with a required set of
physicochemical properties promising for solving var-
ious practical problems, including the preparation of
new photoactive molecules and related materials [6,
7]. As a rule, a step-by-step change in the composi-
tion, geometry of the molecule, and crystal packing of
the compounds makes it possible to reveal the influ-
ence of a number of factors on the physicochemical
properties of new compounds and, thus, to establish
structure–property relationships [8–13]. The use of
aromatic ligands with donor and acceptor substituents
characterized by the formation of strong noncovalent
interactions can provide the control of the geometry of
the molecules and physicochemical properties due to
various intra- and intermolecular noncovalent inter-
actions (C–H···Hal, Hal···Hal, Hal···π, π···π,
N‒O···π, NO2···NO2, hydrogen bonds, and others)
[14–16]. For example, a combination of the pentaflu-
orobenzoic acid anion with various non-fluorinated
aromatic ligands in one molecule can be a convenient
and efficient tool for the purposeful formation of com-
pounds with specified molecular and crystal struc-
tures [17–22].
Our interest in the copper pentafluorobenzoate
complexes is also associated with a diversity of the
behavior of the copper compounds depending on the
type of the coordination environment [23]. When cop-
per ions exist in the octahedral environment, they can
form the same complexes as manganese and cadmium
ions do. For instance, copper and manganese form tri-
fluoroacetate coordination polymers {M2(Рhen)2-
(OOCCF3)4}n [24, 25]. On the one hand, this is possi-
ble due to the Jahn–Teller distortion of the coordina-
tion polyhedron of the Cu(II) atom and two bonds,
whose length can reach 2.6 Å [26]. On the other hand,
the copper ion easily transfers to the square environ-
ment and forms carboxylate complexes typical of pal-
ladium [27–31].
Since the coordination polymers with 2,3-lutidine
and isoquinoline were synthesized in the case of cad-
mium pentafluorobenzoates [32], the formation of
†Deceased.

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 231
similar coordination polymers based on a strongly dis-
torted four-bridge fragment could be expected in the
case of the octahedral environment of the copper ion.
An analysis of available literature data shows that the
copper pentafluorobenzoates contain binuclear four-
bridge fragments with the “Chinese lantern” struc-
ture, but the nonaromatic molecule was coordinated
as the neutral axial ligand in these known examples
[33, 34]. Copper pentafluorobenzoates with the coor-
dinated pyridine derivatives or other heterocyclic
ligands are also known [35–40], but there is no binu-
clear complex with the “Chinese lantern” structure
among them. The four-bridge carboxylate complexes
with the “Chinese lantern” structure are most typical
of copper and, hence, the situation for the known cop-
per pentafluorobenzoates seems to be very unusual.
Since there are many studies devoted to copper car-
boxylates, this state of affairs cannot be occasional.
The situation will undoubtedly be clarified by the
study of the reaction products of copper pentafluoro-
benzoate with α-substituted pyridines. As known, the
use of these ligands provided the formation of the car-
boxylate complexes with the “Chinese lantern” struc-
ture, these complexes were the single reaction prod-
ucts in the predominant part of cases, and even a very
significant excess of α-substituted pyridine is of no
importance [40].
The purpose of this work is to establish what mole-
cules would be formed in the reactions of copper pen-
tafluorobenzoates with 2,4-lutidine and quinoline. To
reveal the presence or absence of a specific role of
α-substituted pyridines, it was reasonable to compare
the result of the reaction of copper pentafluorobenzo-
ate with 3,5-lutidine as well. As will be shown below,
the results of the study turned out to be rather unex-
pected and, therefore, the scope of the studied copper
pentafluorobenzoate complexes was extended, which
was finally justified completely.
EXPERIMENTAL
All procedures related to the synthesis of the com-
plexes were carried out in air using MeCN (99%),
EtOH (96%), Cu(NO3)2·6H2O (reagent grade),
Eu(NO3)3·5H2O (99.99%, Lankhit), pentafluoroben-
zoic acid (HPfb, 98%, P&M-Invest), benzoic acid
(HBnz, reagent grade), KOH (reagent grade), 2,3-
lutidine (2,3-Lut, 98%, Aldrich), 3,5-lutidine (3,5-
Lut, 98%, Aldrich), quinoline (Quin, 98%, Sigma-
Aldrich), and 1,10-phenanthroline (Phen, 99%, Alfa
Aesar). IR spectra were recorded on a Spectrum 65
FT-IR spectrometer (Perkin Elmer) using the attenu-
ated total internal reflectance (ATR) mode in a fre-
quency range of 4000–400 cm–1. Elemental analysis
was conducted on a EuroEA-3000 CHNS analyzer
(EuroVector).
Synthesis of [Cu2(MeCN)2(Pfb)4] (I). Compound
HPfb (1.484 g, 7.000 mmol) was added to a solution of
KOH (0.392 g, 7.000 mmol) in methanol (50 mL), and
the mixture was stirred at 50°С to the complete disso-
lution of the starting reactants. Salt Cu(NO3)2·6H2O
(0.962 g, 3.500 mmol) was added to the resulting solu-
tion, and the mixture was stirred at 50°С for 20 min. A
precipitate of KNO3 formed on stirring was filtered
off, and the obtained blue solution was evaporated at
room temperature to the complete removal of the sol-
vent. The formed blue precipitate was dissolved in ace-
tonitrile (20 mL), and the solution was stored at room
temperature with slow evaporation. Blue crystals suit-
able for X-ray diffraction (XRD) were obtained after
7 days. The crystals of compound I were filtered off,
washed with cold acetonitrile, and dried in air. The
yield of compound I was 1.520 g (82.5% based on
Cu(NO3)2·6H2O).
IR (ATR; ν, cm–1): 36 49 w, 3610 w, 3510 w, 2415 w,
1649 s, 1578 s, 1491 s, 1374 s, 1255 w, 1111 m, 992 s,
902 w, 889 m, 758 s, 521 m, 452 m, 428 m, 405 m.
Synthesis of [Cu(2,3-Lut)2(Pfb)2] (II). Compound
HPfb (0.300 g, 1.410 mmol) was added to a solution of
KOH (0.079 g, 1.410 mmol) in methanol (10 mL), and
the mixture was stirred at 50°С until the complete dis-
solution of the starting reactants. Salt Cu(NO3)2·6H2O
(0.210 g, 0.705 mmol) was added to the obtained solu-
tion, and the mixture was stirred at 50°С for 15 min. A
precipitate of KNO3 formed on stirring was filtered
off, and 2,3-lutidine (0.388 mL, 2.820 mmol, Cu :
2,3-Lut = 1 : 4) was added to the resulting blue solu-
tion. The obtained solution was stored at room tem-
perature with slow evaporation. Crimson-colored
crystals suitable for XRD were formed after 5 days.
The crystals of compound II were filtered off, washed
with cold acetonitrile, and dried in air. The yield of
compound II was 0.202 g (40.9% based on
Cu(NO3)2·6H2O).
IR (ATR; ν, cm–1): 3426 w, 3095 w, 2974 w, 2925 w,
2626 w, 2392 w, 1625 s, 1516 s, 1482 s, 1354 s, 1279 s,
1214 m, 1198 m, 1137 m, 1105 m, 989 s, 924 w, 802 m,
754 s, 717 m, 612 m, 585 m, 517 m, 441 w.
Synthesis of [Cu(3,5-Lut)4(Pfb)2] (III) was carried
out according to a procedure similar to that for com-
pound II using 3,5-lutidine (0.388 mL, 2.820 mmol,
Cu : 3,5-Lut = 1 : 4) instead of 2,3-lutidine. We failed
to obtain crystals suitable for XRD until the solvent
was completely removed. The formed polycrystalline
For C32H6N2O8F20Cu2
Anal. calcd., % C, 36.5 H, 0.6 N, 2.7
Found, % С, 36.7 Н, 0.4 N, 2.9
For C28H18 N2O4F10Cu
Anal. calcd., % C, 48.0 H, 2.6 N, 4.0
Found, % С, 48.2 Н, 2.4 N, 4.3

232
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
KOVALEV et al.
precipitate was repeatedly dissolved in EtOH (8 mL),
and the solution was slowly evaporated at room tem-
perature. Blue crystals suitable for XRD were formed
after 7 days. The crystals of compound III were fil-
tered off, washed with cold water, and dried in air. The
of compound III was 0.532 g (43.2% based on
Cu(NO3)2·6H2O).
IR (ATR; ν, cm–1): 3425 w, 3099 w, 2976 w, 2929 w,
2627 w, 2254 w, 1652 s, 1607 s, 1497 s, 1389 s, 1351 s,
1275 m, 1186 m, 1155 m, 1091 s, 986 s, 921 m, 870 m,
829 m, 747 s, 698 s, 582 m, 522 m.
Synthesis of [Cu(Quin)2(Pfb)2] (IV). Quinoline
(0.024 mL, 0.190 mmol, Cu : Quin = 1 : 1) was added
to a solution of complex I (0.100 g, 0.095 mmol) in
MeCN (10 mL). The resulting solution was stored at
room temperature with slow evaporation. Violet crys-
tals suitable for XRD were obtained after 3 days. The
crystals of compound IV were filtered off, washed with
cold acetonitrile, and dried in air. The yield of com-
pound IV was 0.023 g (36.2% based on Quin).
IR (ATR; ν, cm–1): 3459 w, 3091 w, 2997 w, 2325 w,
2254 w, 1907 w, 1618 m, 1511 s, 1485 s, 1365 s, 1318 m,
1284 m, 1232 w, 1134 w, 1104 m, 1052 w, 991 s, 928 m,
808 s, 762 s, 739 m, 703 m, 637 m, 617 m, 584 w,
524 m, 498 m, 463 m.
Synthesis of [Cu2(Phen)2(Pfb)4] (V). Compound
HBnz (0.041 g, 0.336 mmol) was added to a solution
of KOH (0.019 g, 0.336 mmol) in ethanol (10 mL),
and the mixture was stirred at 50°С until the starting
compounds dissolved completely. A weighed sample
of Eu(NO3)3·5H2O (0.048 g, 0.112 mmol) was added
to the resulting solution, and the mixture was stirred at
50°С for 15 min. A precipitate of KNO3 formed on
stirring was filtered off, and complex I (0.060 g,
0.056 mmol) and 1,10-phenanthroline (0.020 g,
0.112 mmol) were added to the obtained solution. The
resulting mixture was stirred at 50°С for 2 h and stored
at room temperature with slow evaporation. Blue crys-
tals suitable for XRD were obtained after 6 days. The
crystals of compound V were filtered off, washed with
cold acetonitrile, and dried in air. The yield of com-
pound V was 0.016 g (21.3% based on complex I).
For C42H36N4O4F10Cu
Anal. calcd., % C, 51.2 H, 4.0 N, 6.1
Found, % С, 50.9 Н, 4.2 N, 5.9
For C32H14N2O4F10 Cu
Anal. calcd., % C, 51.7 H, 1.9 N, 3.7
Found, % С, 51.8 Н, 1.7 N, 3.6
For C52H16N4O8F20Cu2
Anal. calcd., % C, 46.9 H, 1.2 N, 4.2
Found, % С, 47.1 Н, 1.4 N, 4.3
IR (ATR; ν, cm–1): 3425 w, 3070 w, 2287 w, 1632 m,
1532 s, 1491 s, 139 0 s, 1331 m, 1284 m, 1232 w, 1170 m,
1122 m, 1089 w, 990 s, 945 s, 807 m, 760 m, 709 w,
639 m, 619 w, 589 w, 549 w, 490 w, 469 m.
Synthesis of [Cu2(Phen)2(Pfb)3]·Bnz (VI). Com-
pound HBnz (0.041 g, 0.336 mmol) was added to
KOH (0.019 g, 0.336 mmol) in ethanol (10 mL), and
the solution was stirred at 50°С until the starting
reagents dissolved completely. A weighed sample of
Cu(NO3)2·6H2O (0.050 g, 0.168 mmol) was added to
the obtained solution, and the resulting mixture was
stirred at 50°С for 15 min. A precipitate of KNO3
formed on stirring was filtered off, and complex I
(0.089 g, 0.084 mmol) and 1,10-phenanthroline
(0.061 g, 0.336 mmol) were added to the resulting
solution. The obtained mixture was stirred at 50°С for
30 min and stored at room temperature with slow
evaporation. Blue crystals suitable for XRD were
obtained after 10 days. The crystals of compound VI
were filtered off, washed with cold acetonitrile, and
dried in air. The yield of compound VI was 0.037 g
(35.8% based on complex I).
IR (ATR; ν, cm–1): 3070 m.v.br, 2551 m, 1070 s,
1651 m, 1558 m, 1489 m, 1404 m, 1323 s, 1285 s,
1180 m , 1111 m, 1072 w, 997 s, 931 s, 806 m, 760 m,
712 s, 689 s, 556 m, 543 m, 454 m, 420 m.
XRD of single crystals was carried out on a Bruker
Apex II diffractometer equipped with a CCD detector
(MoKα radiation, λ = 0.71073 Å, graphite monochro-
mator) [41]. A semiempirical absorption correction
was applied using the SADABS program [42]. The
structures were solved by a direct method and refined
by least squares first in the isotropic approximation
and then in the anisotropic approximation for
The positions of hydrogen atoms were calculated geo-
metrically and refined in the isotropic approximation
by the riding model. All calculations were performed
using the SHELXL-2018/3 software [43] and Olex2
[44]. In the structure of complex I, the pentafluoro-
phenyl fragments are disordered over two positions
with the occupancies 0.642/0.358. In the structure of
compound V, the O(4) oxygen atom of the carboxy
group is disordered over two positions with the occu-
pancies 0.72/0.28. The geometries of the metal atom
polyhedra were determined using the SHAPE 2.1 pro-
gram [45]. The crystallographic parameters and struc-
ture refinement details for compounds I–VI are listed
in Tables 1 and 2.
For C52H9N4O8F15Cu2
Anal. calcd., % C, 50.3 H, 1.7 N, 4.5
Found, % С, 50.4 Н, 1.9 N, 4.4
2
.
hkl
F

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 233
The structural data for compounds I–VI were
deposited with the Cambridge Crystallographic Data
Centre (CIF files CCDC nos. 2214307 (I), 2214304
(II), 2214305 (III), 2214306 (IV), 2218311 (V), and
2217785 (VI)) and are available at deposit@
ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/
data_request/cif.
In order to evaluate contributions of different non-
covalent interactions to the crystal packings of the syn-
thesized complexes, we examined the Hirshfeld sur-
face using the Crystal Explorer 17 program [46, 47].
RESULTS AND DISCUSSION
The reaction of copper nitrate with pentafluoro-
benzoic acid potassium salt (prepared without isola-
tion by the reaction of potassium hydroxide with pen-
tafluorobenzoic acid) in a methanol–acetonitrile
mixture affords crystals of compound [Cu2(MeCN)2-
(Pfb)4] (I, Scheme 1) with the “Chinese lantern”
structure typical of the binuclear copper complexes.
However, the four-bridge binuclear metal cage of
complex I was not retained in the reactions with vari-
ous pyridine derivatives.
Table 1. Crystallographic parameters and structure refinement details for compounds I–III
Parameter
Value
IIIIII
Empirical formula C32H6N2O8F20Cu2C28H18N2O4F10Cu C42H36N4O4F10Cu
FW 1053.47 699.98 914.29
Т, K 296(2) 100(2) 100(2)
Crystal system Monoclinic Triclinic Monoclinic
Space group C2/cP21/n
a, Å 13.776(3) 7.5374(5) 12.8343(10)
b, Å 17.410(4) 8.8184(7) 9.0410(7)
c, Å 14.837(3) 10.3150(7) 17.6667(14)
α, deg 90 85.157(3) 90
β, deg 91.08(3) 84.742(3) 104.398(3)
γ, deg 90 75.366(3) 90
V, Å33557.8(12) 659.25(8) 1985.6(3)
Z412
ρcalc, g/cm31.967 1.763 1.529
μ, mm–1 1.356 0.940 0.646
θmax, deg 25.999 25.995 25.998
Number of measured reflections 8757 5608 11466
Number of independent reflections 3409 2489 3884
Number of reflections with I > 2σ(I) 2679 2224 3088
Rint 0.0565 0.0647 0.0402
Number of refined parameters 3519 3435 3815
GOOF 1.114 1.036 1.027
R1 (I > 2σ(I)) 0.0610 0.0467 0.0374
wR2 (I > 2σ(I)) 0.1150 0.1190 0.0861
Δρmin/Δρmax, е Å–3 –0.713/0.430 –0.961/0.726 –0.405/0.308
1
P

234
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
KOVALEV et al.
The general scheme of the synthesis of
complexes I–VI is shown in Scheme 1.
Scheme 1.
The reaction of copper pentafluorobenzoate with a
fourfold 2,3-lutidine or 3,5-lutidine excess resulted in
the formation of mononuclear complexes [Cu(2,3-
Lut)2(Рfb)2] (II, Scheme 1) and [Cu(3,5-Lut)4(Рfb)2]
(III, Scheme 1). A fourfold excess of 2,3-Lut and 3,5-
Lut was used to increase the yield of the expected reac-
tion product, since our previous experience indicated
that such an excess allowed the preparation of a single-
phase complex in an almost quantitative yield in the
case of the compounds with the “Chinese lantern”
structure [40].
Taking into account the composition of com-
pound II, the Cu to Quin ratio was decreased to 1 : 1
in the reaction of complex I with quinoline, and ace-
tonitrile was used as the solvent. This resulted in the
formation of compound [Cu(Quin)2(Pfb)2] (IV,
Scheme 1) analogous to complex II; i.e., in the case of
such α-substituted pyridines as 2,3-lutidine and quin-
oline, the compositions and structures of the final
reaction products of copper pentafluorobenzoate were
the same, although the initial ratio of the reagents and
solution composition varied.
Since heterometallic pentabenzoates {Cd2Ln2} and
{Zn2Ln2} were described for cadmium and zinc [48–
51], it seemed reasonable to synthesize Cu(II)–
Cu(NO3)2 6H2O + 2(KOH + HPfb)
MeOH, MeCN
+4(2,3-Lut)
MeOH
+Qui n
MeCN
Cu Cu MeCN
MeCN
Cu2(MeCN)2(Pfb)4 (I)
R
O
O
Cu
OO
N
R
N
Cu(2,3-Lut)2(Pfb)2 (II)
Cu
O
O
R
N
Cu(3,5-Lut)2(Pfb)2 (III)
MeOH, EtOH
+4(3,5-Lut)
NN
N
RO
O
R
O
O
Cu
O
O
N
R
Cu(Quin)2(Pfb)2(IV)
NCu Cu
R
OO
O
O
R
N
N
N
N
[Cu2(Phen)2(Pfb)3]+Bnz (VI)
R
OO
+{Cu(Bnz)2},
EtOH
R
O
O
=
OOC
F F
F
FF
Phen
Cu Cu
R
OO
O
O
R
N
N
N
N
Cu2(Phen)2(Pfb)4 (V)
O
O
R
R'
OO
+{Eu(Bnz)3},
EtOH
Phen
R'
O
O
=
OOC
H H
H;
HH
;R
O
O
=P2-K1: K1
.

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 235
Ln(III) complexes to obtain a more comprehensive
information about copper pentafluorobenzoates.
Similar complexes were described earlier for anions of
other monocarboxylic acids [52–55]. The result of the
synthesis for which we planned to obtain a heterome-
tallic Cu(II)–Ln(III) complex with 1,10-phenanthro-
line was unexpected, since the homometallic complex
[Cu2(Phen)2(Pfb)4] (V, Scheme 1), which has previ-
ously been detected in the composition of solvate
[Cu2(Phen)2(Pfb)4]·2НPfb [56], was isolated instead
of the expected molecular compound [Cu2Eu2-
(Phen)2(Pfb)10].
The formation of complex V shows that heterome-
tallic Cu(II)–Ln(III) pentafluorobenzoate is unsta-
ble, most likely, in the system used. It should be men-
tioned that one of the results of the action of noncova-
lent interactions of the arene–perfluoroarene type in
the systems studied is the destruction of heterometal-
lic fragments, which are highly stable in the most part
of other carboxylate anions (pivalate, benzoate, and
furoate). For instance, many heterometallic com-
plexes of the [M2Li2L2(OOCR)6], [M2MgL2-
(OOCR)6], [M2Ln2L2(OOCR)10], or [M2LnL2-
(OOCR)7] type (М = Ni(II), Co(II), Cu(II), Zn(II),
and Cd(II); L is the monodentate or chelating
N-donor ligand) are resistant to the action of a multi-
fold excess of monodentate and chelating pyridine
derivatives [57–62]. A similar “destructive” role of
aromatic N-donor ligands was observed for cadmium
pentafluorobenzoates, where only homometallic cad-
mium compounds were isolated as a result of attempts
to synthesize the complexes with 2,4-lutidine and iso-
quinoline [32]. We succeeded to synthesize the heter-
ometallic complex [Cd2Ln2(Ру)4(Рfb)10] with the
monodentate N-donor ligand. However, this complex
readily decomposed with a minor pyridine excess to
[Cd(Ру)3(Рfb)2] [32], whereas the stable Cd(II)–
Ln(III) compounds were formed by cadmium with
1,10-phenanthroline [51]. In the case of copper, we
observed still more “destructive” role of aromatic
ligands, which is manifested in the fact that a hetero-
metallic Cu(II)–Ln(III) complex cannot be synthe-
sized even with the chelating ligand, although these
compounds are formed in the case of other carboxyl-
ate anions [55, 63].
Table 2. Crystallographic parameters and structure refinement details for compounds IV–VI
Parameter Value
IV V VI
Empirical formula C32H14CuF10N2O4C52H16Cu2F20N4O8C52H21Cu2F15N4O8
FW 743.99 1331.77 1241.81
Т, K 150(2) 296(2) 100(2)
Crystal system Triclinic Triclinic Orthorhombic
Space group Pnna
a, Å 7.3250(5) 9.5223(10) 25.0562(19)
b, Å 9.4595(6) 10.6768(12) 13.8791(10)
c, Å 10.3994(6) 12.7802(12) 15.6130(13)
α, deg 84.816(2) 81.280(4) 90
β, deg 82.975(2) 71.143(5) 90
γ, deg 78.030(2) 81.832(5) 90
V, Å3698.05(8) 1209.4(2) 5429.5(7)
Z114
ρcalc, g/cm31.770 1.829 1.519
μ, mm–1 0.894 1.020 0.890
θmax, deg 30.597 30.509 24.713
Number of measured reflections 7805 15 098 36 099
Number of independent reflections 4218 7320 4643
Number of reflections with I > 2σ(I)3843 5801 3309
Rint 0.0166 0.0279 0.10 41
Number of refined parameters 4822 856 4137
GOOF 0.936 1.051 1.039
R1 (I > 2σ(I)) 0.0305 0.0496 0.0634
wR2 (I > 2σ(I)) 0.1151 0.1005 0.1580
Δρmin/Δρmax, е Å–3 –0.418/0.428 –0.370/0.330 –1.135/1.053
1
P
1
P

236
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
KOVALEV et al.
Such a specific behavior of copper in the pentaflu-
orobenzoate systems shows that it is almost impossible
to predict results of the reactions, which were studied
in detail for cadmium and zinc and, hence, can be
planned surely. This compelled us to reproduce the
experiment in which the expected result was not
obtained in the case of cadmium. We attempted to
synthesize a heteroanionic cadmium compound in
which pentafluorobenzoate and benzoate anions
would be combined with 1,10-phenanthroline. Instead
of this compound, only crystals of the known coordi-
nation polymer {Cd(Рhen)(Рfb)2}n were isolated in a
high yield [64]. A very unusual heteroanionic
[Cu2(РhenРfb)3]+(Вnz)– compound (VI, Scheme 1)
was isolated from the reaction of copper benzoate and
pentafluorobenzoate with 1,10-phenanthroline in eth-
anol.
Complex I crystallizes in the monoclinic space
group С2/с. Compound I consists of two copper cat-
ions linked with each other by four μ2-η1:η1-bridging
Рfb– anions (Fig. 1, distance Cu···Cu 2.724(1) Å; Cu–
O bond lengths lie in a narrow range of 1.971(4)–
1.978(3) Å). Each copper ion additionally coordinates
the nitrogen atom of the MeCN molecule (Cu(1)–
N(1) 2.147(2) Å). For compound I, the Cu–O and
Cu–N bond lengths, as well the Cu···Cu distance, lie
in the range characteristic of the copper complexes
with the “Chinese lantern” structure [65–67]. No sig-
nificant distortion of the geometry of compound I is
observed compared to that of the copper benzoate
complex [Cu2(MeCN)2(Вnz)4] [68]. The geometry of
the CuO4N coordination polyhedron was analyzed
using the Shape2.1 program and corresponds to a
tetragonal pyramid (Sq(Cu) = 0.323, copper ion shifts
from the O4 pyramid base by 0.234(2) Å).
The crystal packing of complex I exhibits a parallel
orientation of the pentafluorobenzoate anions of the
adjacent molecules, which possibly indicates the pres-
ence of π···π interactions between the aromatic frag-
ments (Table 3). The intermolecular noncovalent
interactions C–F···π (Table 4), F···F (Table 5),
C‒H···F, and C–H···O (Table 6) resulting in the sta-
bilization of the supramolecular cage structure can
also be emphasized. It was revealed that the main con-
tribution to the Hirshfeld surface of complex I was
made by the F···F, H···F, C···F, F···O, and C···C inter-
actions (Table 7).
Complexes II and IV crystallize in the triclinic
space group P with the inversion center on the metal
ion and have similar structures. The copper ions in the
structures of compounds II and IV coordinate two
_
1
Fig. 1. Structure of complex I.
C
H
Cu
F
N
O
Fig. 2. Structure of complexes (a) II and (b) IV. The Cu···O
contacts are shown by dash.
C
H
Cu
(а)
(b)
F
N
O
C
H
Cu
F
N
O

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 237
oxygen atoms of two η1-Pfb– anions (Fig. 2, Cu(1)–
O(1) 1.970(2) Å for complex II and Cu(1)–O(2)
1.969(1) Å for complex IV) and two N atoms of two
monodentate ligands (Cu(1)–N(1) 1.996(2) Å for
complex II and Cu(1)–N(1) 2.010(2) Å for
complex IV) to form the square environment
(Sq(Cu) = 0.010 for complex II; Sq(Cu) = 0.011 for
complex IV). The distance between the copper ions
and oxygen atoms of the carboxy groups that are not
involved in coordination is Cu(1)–O(2) 2.767(2) Å for
complex II and Cu(1)–O(1) 2.628(1) Å for complex
IV, which can be considered as a relatively weak inter-
action [29, 31]. The monodentate coordination mode
of the pentafluorobenzoate anion is also confirmed by
a significant difference in the C–O bond lengths of the
carboxy groups (C(1)–O(1) 1.227(3); C(1)–O(2)
1.270(3) Å for complex II; C(1)–O(1) 1.230(2); C(1)–
O(2) 1.269(1) Å for complex IV) [31]. The dihedral
angles between the planes formed by the aromatic
fragments of the pentafluorobenzoate anions and N-
donor ligands are 87.66(10)° for complex II and
88.43(10)° for complex IV. The close bond lengths and
angles in the structures of compounds II and IV indi-
cate that the replacement of the 2,3-Lut molecule by
Quin exerts no substantial effect on the geometry of
the synthesized complexes.
The crystal packings of complexes II and IV exhibit
the formation of π···π interactions between pairs of the
N-donor ligand molecules and Pfb anions, whereas
no interactions of the arene–perfluoroarene type
are observed (Fig. 3, Table 3). According to the
Hirshfeld surface analysis, the main contribution to
the stabilization of the crystal packing is made by the
C···C, C···F, H···F, F···F, and O···H interactions
(Tables 4–7), and the replacement of 2,3-lutidine by
quinoline in the structure of the complex does not lead
to a significant change in the scheme of noncovalent
interactions.
The number of the synthesized copper carboxylate
compounds with the square environment of the metal
center similar to complexes II and IV is much lower
than the number of more typical complexes with the
“Chinese lantern” structure. The binuclear com-
pounds with the “Chinese lantern” structure were also
synthesized for combinations of a specific carboxylate
anion and N-donor ligand capable, as a rule, of form-
Table 3. Interactions π···π in the crystal packings of complexes I–VI*
* Cg is the centroid of aromatic rings, Perp is the perpendicular to the ring plane, and α is the angle between planes of aromatic fragments.
Interaction Cg···Cg, Å Symmetry code Cg···Perp, Å α, deg
I
Pfb···Pf b 3.650(3) 2 – x, y, 1/2 – z3.541(2) 15.9(2)
Pfb···Pf b 3.621(4) 1 – x, 1 – y, 1 – z3.465(3) 0.0(3)
Pfb···Pf b 3.634(8) 1 – x, 1 – y, 1 – z3.465(3) 7.8(6)
Pfb···Pfb 3.756(10) 1 – x, 1 – y, 1 – z3.357(7) 0.0(8)
II
2,3-Lut···2,3-Lut 3.7261(18) 1 – x, y, 1 – z3.4135(12) 0.00(14)
Pfb···Pfb 3.5397(18) 2 – x, 1 – y, – z3.2713(13) 0.00(15)
III
3,5-Lut···3,5-Lut 3.7173(11) 1 – x, 2 – y, 1 – z3.3475(8) 0.02(10)
IV
Pfb···Pf b 3.4921(9) –x, 1 – y, 2 – z3.3316(6) 0.00(7)
Quin···Quin 3.8262(7) 1 – x, 1 – y, 2 – z3.5040(5) 0.02(4)
V
Phen···Pfb 3.5860(16) 1 – x, 1 – y, 1 – z3.3622(11) 7.29(13)
Phen···Phen 3.5726(16) 1 – x, 2 – y, 1 – z3.4509(11) 0.00(13)
VI
Phen···Pfb 3.600(3) x, 3/2 – y, 3/2 – z3.396(2) 2.2(2)
Phen···Phen 3.592(3) 1 – x, 1 – y, 2 – z3.3958(19) 0.2(2)
Bnz···Pfb 3.629(3) x, y, z 3.4555(19) 3.1(3)
Pfb···Pf b 3.777(3) 1 – x, 1 – y, 1 – z3.497(2) 0.0(3)

238
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KOVALEV et al.
Table 4. Interactions С–F···π in the crystal packings of complexes I, II, and IV–VI*
* Cg is the centroid of aromatic rings, Perp is the perpendicular to the ring plane, and α is the angle between planes of aromatic fragments.
Interaction F···Cg, Å Symmetry code F···Perp, Å Angle C–O···Cg, deg
I
С(11A)–F(11A)···π(Рfb) 3.441(7) x, 1 – y, 1/2 + z3.328 106.8(5)
C(13A)–F(13A)···π(Рfb) 3.211(7) 1 – x, y, 3/2 – z3.068 104.6(4)
C(14A)–F(14A)···π(Рfb) 3.573(10) 1 – x, 1 – y, 1 – z3.130 69.4(4)
C(11B)–F(11B)···π(Рfb) 3.360(9) x, 1 – y, 1/2 + z2.994 97.0(8)
C(13B)–F(13B)···π(Рfb ) 3.492(9) 1 – x, y, 3/2 – z3.025 115.1(8)
C(14B)–F(14B)···π(Рfb) 3.660(16) 1 – x, y, 3/2 – z3.399 69.2(10)
II
С(4)–F(4)···π(Рfb) 3.491(2) 2 –x, 1 – y, –z3.212 69.31(15)
С(5)–F(5)···π(2,3-Lut) 3.171(2) 1 + x, y, –1 + z3.048 147.79(18)
IV
C(3)–F(3)···π(Pfb) 3.5189(12) 1 – x, 1 – y, 1 – z3.312 152.47(8)
C(4)–F(4)···π(Pfb) 3.6652(13) –x, 1 – y, 2 – z3.263 65.62(8)
C(5)–F(5)···π(Quin) 3.3138(13) –1 + x, y, 1 + z3.174 142.94(10)
V
C(3)–F(3)···π(Phen) 3.648(2) 2 – x, 1 – y, 1 – z3.441 19.36
C(6)–F(6)···π(Phen) 3.639(2) 1 – x, 1 – y, 1 – z3.277 25.77
C(7)–F(7)···π(Phen) 3.4746(19) 1 – x, 1 – y, 1 – z3.102 26.77
C(10)–F(10)···π(Phen) 3.373(2) 1 – x, 1 – y, 1 – z3.244 15.90
C(13)–F(13)· ··π(Pfb) 3.249(2) 2 – x, 1 – y, –z3.159 13.54
C(14)–F(14)···π(Pfb) 3.635(2) 2 – x, 1 – y, 1 – z3.209 28.03
VI
C(4)–F(4)···π(Phen) 3.701(4) x, 3/2 – y, 3/2 – z3.376 67.0(3)
C(6)–F(6)···π(Phen) 3.536(5) x, 3/2 – y, 3/2 – z3.312 71.5(3)
C(7)–F(7)···π(Phen) 3.484(5) x, 3/2 – y, 3/2 – z3.433 91.1(3)
C(10)–F(10)···π(Bnz) 3.773(4) 3/2 – x, 1/2 + y, 3/2 – z3.411 66.5(3)
Table 5. Interactions F···F in the crystal packings of complexes I, IV, and VI
Interaction
F···F d, Å Symmetry code % of sum of van
der Waals radii
I
F(3)···F(10B) 2.898(11) 98.5
F(5)···F(10B) 2.711(12) x, 1 – y, –1/2 + z92.2
F(6)···F(11B) 2.879(9) 3/2 – x, 1/2 + y, 1/2 – z97.9
F(6)···F(14A) 2.894(8) 1/2 + x, 3/2 – y, –1/2 + z98.4
F(7)···F(14A) 2.702(8) 1/2 + x, 3/2 – y, –1/2 + z91.9
IV
F(4)···F(5) 2.880(2) 2 – x, 2 – y, 1 – z97.9
V
F(3)···F(4) 2.930(3) 1 – x, 1 – y, 2 – z98.6
VI
F(6)···F(11) 2.738(5) –1/2 + x, 3/2 – y, –1/2 + z93.1
F(5)···F(5) 2.828(4) x, 3/2 – y, 3/2 – z95.9
F(12)···F(11) 2.719(4) x, 3/2 – y, 3/2 – z92.2

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 239
ing mononuclear complexes of the discussed type. For
instance, monochloroacetate with 2-methylpyridine
[Cu(L)2(OOCR)2] [69] and binuclear complex
[Cu2(L)2(μ-OOCR)4] [70] are known. The same situ-
ation is observed for the benzoate complexes with
2-aminopyridine [71], and benzoates form binuclear
[Cu2(L)2(μ-OOCR)4] complexes with other aromatic
N-donor ligands as well [67, 72, 73].
Complex III crystallizes in the monoclinic space
group P21/n with the inversion center on the metal
ion. The octahedral environment of the copper ions in
the structure of complex III is formed due to two oxy-
gen atoms of the η1-Pfb– anions and four nitrogen
atoms of four 3,5-Lut molecules (Fig. 4, Sq(Cu) =
0.946). An insignificant distortion of the metal ion
polyhedron is also confirmed by the bond angles
Table 6. Interactions С–H···F and С–H···O in the crystal packings of complexes I and III–VI
D–H···A Distance, Å Symmetry code Angle
D–H···A, deg
D–H H···A D···A
I
C(10)–H(10)···F(7) 0.95 2.49 3.280(4) 1 – x, –y, 1 – z141
C(11)–H(11)···O(2) 0.95 2.49 3.193(4) 1 + x, y, z 130
C(13)–H(13C)···F(3) 0.98 2.49 3.305(4) 1 – x, 1 – y, 1 – z141
III
C(8)–H(8)···O(1) 0.95 2.25 2.974(3) 152
C(12)–H(12)···O(1) 0.95 2.41 3.142(3) 1 – x, 1 – y, 1 – z159
C(14)–H(14C)···F(5) 0.95 2.53 3.494(3) 3/2 – x, –1/2 + y, 3/2 – z173
C(15)–H(15)···O(1) 0.95 2.43 3.038(3) 158
C(19)–H(19)···O(2) 0.95 2.30 3.204(3) 1 – x, 1 – y, 1 – z144
IV
C(9)–H(9)···O(1) 0.95 2.42 3.175(5) 1 + x, y, z 136
C(15)–H(15)···F(4) 0.95 2.55 3.254(2) x, 1 + y, –1 + z131
V
C(25)–H(25)···O(2) 0.93 2.39 3.192(3) 1 – x, 2 – y, 1 – z14 4
C(26)–H(26)···O(4B) 0.93 2.38 3.238(10) 1 – x, 2 – y, 1 – z152
VI
C(5S)–H(5S)···F(3) 0.95 2.49 3.236(10) 135
C(13)–H(13)···F(10) 0.95 2.39 3.232(6) 148
C(17)–H(17)···F(5) 0.95 2.40 3.153(6) x, y, 1 + z136
Table 7. Contribution of noncovalent interactions to the total Hirshfeld surface of complexes I–VI
Interaction
Compound
IIIIIIIVVVI
%
C···C 7.1 5.0 2.1 8.3 8.3 10.8
C···F 18.3 14.7 6.6 14.6 7.8 2.8
H···F 23.0 35.7 33.4 36.7 40.4 32.7
F···F 27.9 6.7 2.1 6.0 17.2 11.0
O···F 10.5 3.8 2.0 4.5 4.1 3.0
O···H 3.9 8.4 1.9 6.2 8.8 11.3

240
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
KOVALEV et al.
N(1)Cu(1)N(2) (89.90(7)°) and N(1)Cu(1)O(1)
(92.49(6)°). The Cu–N distances (2.060(2) and
2.030(2) Å) in complex III are typical of Cu–N bonds,
whereas the Cu(1)–O(1) bond considerably elongates
(2.483(4) Å). The O(2) atoms are not involved in the
coordination to the copper ions, and the Cu(1)···O(2)
distance is 4.155(2) Å.
As in the case of complexes II and IV, the crystal
packing of compound III contains no interactions of
the arene–perfluoroarene type, whereas pairs of 3,5-
Lut molecules form π···π interactions (Table 3). The
intermolecular noncovalent C–H···F and C–H···O
interactions also contribute to the stabilization of the
crystal packing (Table 6) and result in the stabilization
of the supramolecular cage structure. According to the
Hirshfeld surface analysis, the main contribution to
the crystal packing stabilization is made by the C···F
and H···F interactions (Table 7), whereas the
contribution of the C···C, F···F, and O···H
interactions decreases significantly compared to that
for complexes II and IV.
According an analysis of the Cambridge Structural
Database (CSD), only several examples of the copper
complexes with the composition [Cu(RCOO)2(L)4],
where RCOO is the carboxylic acid anion, and L is the
monodentate N-donor ligand, are described [74–80].
An insignificant number of the complexes with 3d-
metal ions similar to complex III was described, and
the most part of them was synthesized using the crys-
tallization of anhydrous carboxylates from a pyridine
solution [74, 81–87]. An inert atmosphere and the
absence of water were necessary for the synthesis of
iron pivalate and acetate [Fe(Рy)4(OOCR)2] [84, 85],
whereas these conditions were possibly needless for
Fig. 3. Fragment of the crystal packing of complex IV. The aromatic cycles between which π···π interactions occur are shown by
dash.
C
H
Cu
F
N
O
3.492(1)
3.738(1)
Fig. 4. Structure of complex III.
C
H
Cu
F
N
O

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 241
manganese [88], copper [79], and cobalt [87] trifluo-
roacetates. Probably, complexes of the
[М(Ру)4(OOCR)2] type with anions of strong carbox-
ylic acids will be formed in many other cases as well.
Complex V crystallizes in the triclinic space group
with the inversion center between two copper ions.
In the structure of complex V, the metal ions are linked
with each other via two η1-Рfb– anions with the for-
mation of the binuclear metallic cage (Fig. 5, Cu(1)–
O(1) 1.968(2), Cu···Cu 3.3681(3) Å, angle
Cu(1)O(1)Cu(1) 100.81(8)°). Each metal ion builds
up its environment to a square pyramid due to the
coordination of the Рfb– anion and chelate-bound
Рhen molecule (Cu(1)–O(3) 1.939(1), Cu(1)–N(1)
2.018(2), Cu(1)–N(2) 2.026(2) Å, Sq(Cu) = 1.667).
The O(2) and O(4) atoms are not involved in the coor-
dination to the copper ions, and the Cu(1)···O(2) and
Cu(1)···O(4) distances are 2.997(4) and 3.084(2) Å,
respectively, which exceed the sums of the van der
Waals radii.
The aromatic fragments of the Рfb– anions in the
crystal packing of compound V are involved in the for-
mation of π···π interactions of the arene–perfluoro-
arene type with the 1,10-Рhen molecules to form a
supramolecular chain directed along the а axis (Fig. 6,
Table 3). The crystal packing is also stabilized by the
F···F, C–F···π, and C–H···O interactions (Tables 4–6)
with the formation of a layered supramolecular struc-
ture. According to the Hirshfeld surface analysis, the
main contribution to the crystal structure stabilization
1
P
is made by the H···F, F···F, O···H, and C···C interac-
tions (Table 7).
The binuclear copper complexes with the structure
similar to that of compound V were earlier synthesized
for a series of mono- [56, 89–97] and dicarboxylic
acids [93, 98–101]. The binuclear copper pentafluo-
robenzoate complexes similar to complex V with sol-
vate molecules of pentafluorobenzoic acid ([Cu2-
(Рhen)2(Рfb)4]·2HРfb [56]) and with 2,2'-bipyridyl
(Вpy) as the N-donor ligand ([Cu2(Вpy)2(Рfb)4] [94])
were also synthesized. The replacement of Вpy by
Рhen in the structure of the binuclear copper penta-
fluorobenzoate complex does not result in a signifi-
cant change in the geometry of the molecule, but an
approach of the aromatic cycles of the pentafluoro-
benzoate anions and N-donor ligand molecules by
~0.3 Å is observed, which possibly indicates the
enhancement of noncovalent interactions of the
arene–perfluoroarene type. The introduction of a sol-
vate acid molecule results in the formation of addi-
tional π···π interactions between the aromatic anions
and solvate molecules of the acid, which exerts no sub-
stantial effect on the geometry of the binuclear mole-
cule.
A specific feature of complex V is that its structure
is nearly the same as the structure of the binuclear
fragment of the {Cd(Рhen)(Рfb)2}n coordination poly-
mer [64]. However, although the structure of com-
pound V is preorganized for polymerization, its mole-
cule is very stable owing to the coordination saturation
of the copper atom. Stacking interactions between the
Fig. 5. Structure of complex V.
C
H
Cu
F
N
O

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KOVALEV et al.
Рhen molecules and pentafluorophenyl substituents
of the carboxylate anions are observed in both the
{Cd(Рhen)(Рfb)2}n coordination polymer and binu-
clear complex V. Owing to this, the aromatic fragments
are oriented in parallel and form an “oblate” structure.
If the binuclear fragment is “cut” from the
{Cd(Рhen)(Рfb)2}n coordination polymer, this frag-
ment would contain unblocked coordinatively unsatu-
rated metal centers. Under the real conditions, this
structure can be stable only due to the coordination of
additional ligands, as it took place for the formation of
unusual binuclear 2,3,4,5-tetrafluorobenzoate com-
plexes [Cd2(H2O)2(Рhen)2(OOCC6F4H)4] and
[Cd2(H2O)2(Quin)2(OOCC6F4H)4] [64].
Complex VI crystallizes in the orthorhombic space
group Pnna. Compound VI consists of the binuclear
[Cu2(Pfb)3(Phen)2]+ cation and outer-sphere anion of
benzoic acid. In the binuclear cation, two copper ions
are bound to each other via one μ2-η1:η1 Pfb– and two
η1-Рfb– anions (Fig. 7; Cu(1)–O(1) 2.324(3),
Cu(1A)–O(1A) 1.951(3), Cu(1)–O(3) 1.942(3), and
Cu···Cu 3.237(1) Å). Each copper anion builds up its
environment to a tetragonal pyramid due to the coor-
dination of two nitrogen atoms of the Phen molecule
(Cu(1)–N(2) 1.991(4), Cu(1)–N(1) 2.003(5) Å;
Sq(Cu) = 2.482). The O(2) atom is not involved in the
coordination to the copper ions, and the Cu(1)···O(2)
distance is 2.991(4) Å.
Compound VI is unusual, because anions of a
stronger carboxylic acid are coordinated and an anion
of a much weaker acid becomes the outer-sphere
anion (pKa(HBnz) = 4.20, pKa(HPfb) = 1.48). As a
rule, benzoate anions in the carboxylate systems can-
not be outer-sphere, whereas this function is rather
usual for anions of strong carboxylic acids [102–104].
Some three-bridge cationic copper complexes with
monocarboxylic acid anions similar to compound VI
are known [105–110], but the stronger acid anions
were counterions in all known examples.
All aromatic fragments in compound VI are
involved in the π···π interactions (Fig. 8). The struc-
Fig. 6. Fragment of the crystal packing of complex V. The aromatic cycles between which π···π interactions occur are shown by
dash.
C
H
Cu
F
N
O
3.573(3)
3.586(2)

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 49 No. 4 2023
INFLUENCE OF THE AROMATIC LIGAND NATURE AND SYNTHESIS CONDITIONS 243
ture of the binuclear cation exhibits stacking interac-
tions between the coordinated 1,10-phenanthroline
molecules and pentafluorophenyl substituents of the
anions (Table 3). One pentafluorobenzoate anion is
not involved in the intramolecular stacking but partic-
ipates in the π···π interactions with the outer-sphere
anion of benzoic acid, which results in the formation
of supramolecular chains directed along the b axis.
The crystal packing of complex VI is also stabilized by
a series of C–F···π, C–H···F, and F···F interactions
(Tables 4–6). The main contribution to the Hirshfeld
surface is made by the H···F, F···F, O···H, and C···C
interactions. We can also mention an increase in the
role of the O···H and C···C interactions and a signifi-
cant decrease in the role of the H···F and F···F interac-
tions upon the introduction of the benzoate anion into
the structure of heteroanionic complex VI compared
to pentafluorobenzoate complex V (Table 7).
Thus, we showed that the substitution of coordi-
nated acetonitrile molecules in complex I by aromatic
heterocyclic N-donor ligands led to the destruction of
the binuclear metal cage and formation of different
mononuclear compounds. Probably, since in the sys-
tems considered the copper atom forms no octahedral
environment, no analogs of the cadmium pentafluo-
robenzoate coordination polymers with heterocyclic
monodentate N-donor ligands were prepared. The
stability of the [Cu2(Рhen)2(Рfb)4] binuclear complex
is determined by the tetragonal pyramidal environ-
ment of the copper atoms that are coordinatively satu-
rated in this complex. It is shown for the heteroanionic
copper benzoate pentafluorobenzoate complex that
the introduction of the aromatic anion of the second
type results in the stabilization of the untypical ionic
compound in which the anion of a weaker acid acts as
the outer-sphere counterion.
ACKNOWLEDGMENTS
XRD, IR spectroscopy, and C,H,N,S analysis were car-
ried out using the equipment of the Center for Collective
Use of Physical Methods of Investigation at the Kurnakov
Institute of General and Inorganic Chemistry (Russian
Academy of Sciences) supported by state assignment of the
Kurnakov Institute of General and Inorganic Chemistry
(Russian Academy of Sciences) in the field of basic
research.
Fig. 7. Structure of compound VI.
C
H
Cu
F
N
O

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KOVALEV et al.
FUNDING
This work was supported by the Russian Science Foun-
dation, project no. 22-73-10192.
CONFLICT OF INTEREST
The authors declare that they have no conflicts of
interest.
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Translated by E. Yablonskaya