Synthesis of novel N- and S-derivatives of 2-naphthol – Promising ligands for the binuclear copper complexes

Article abstract of DOI:10.1016/j.poly.2020.114678

N- And S-ligands for binuclear copper complexes were synthesized by the C-sp²-aminomethylation of 2-naphthol with N,N,N′,N′-tetramethyldiaminomethane giving 1-dimethylaminomethyl-2-naphthol, which then reacted with 1,2-ethanedithiol to be converted to thiomethylated derivative. Direct thiomethylation of 2-naphthol and its acetate with formaldehyde and 1,2-ethanedithiol is nonselective, because the reaction involves both O- and C-sp² reaction centers of the substrate. Binuclear copper complexes with Cu-O-Cu-N or Cu-Cl-Cu-S bonds were prepared.

Full text of DOI:10.1016/j.poly.2020.114678

Journal Pre-proofs
Synthesis of Novel N- and S-Derivatives of 2-Naphthol - Promising Ligands
for the Binuclear Copper Complexes
Vnira R. Akhmetova, El'mira M. Bikbulatova, Ekaterina S. Mescheryakova,
Nail S. Akhmadiev, Marat F. Abdullin, Askhat G. Ibragimov
PII:
S0277-5387(20)30335-1
DOI:
Reference:
https://doi.org/10.1016/j.poly.2020.114678
POLY 114678
To appear in:
Polyhedron
Received Date:
Revised Date:
Accepted Date:
11 March 2020
10 June 2020
15 June 2020
Please cite this article as: V.R. Akhmetova, E.M. Bikbulatova, E.S. Mescheryakova, N.S. Akhmadiev, M.F.
Abdullin, A.G. Ibragimov, Synthesis of Novel N- and S-Derivatives of 2-Naphthol - Promising Ligands for the
Binuclear Copper Complexes, Polyhedron (2020), doi: https://doi.org/10.1016/j.poly.2020.114678
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Synthesis of Novel N- and S-Derivatives of 2-Naphthol - Promising Ligands
for the Binuclear Copper Complexes
Vnira R. Akhmetovaa, El'mira M. Bikbulatovaa, Ekaterina S. Mescheryakovaa, Nail S.
Akhmadieva, Marat F. Abdullinb, Askhat G. Ibragimova
aInstitute of Petrochemistry and Catalysis of Russian Academy of
Sciences, 141 Prospekt Oktyabrya, Ufa 450075, Russian Federation
vnirara@mail.ru
bUfa Institute of Chemistry of Russian Academy of Sciences, 71 Prospekt Oktyabrya,
Ufa 450054, Russian Federation mfabdullin@gmail.com
Abstract N- And S-ligands for binuclear copper complexes were synthesized by the
С-sp2-
1-
aminomethylation of 2-naphthol with N,N,N',N'-tetramethyldiaminomethane giving
dimethylaminomethyl-2-naphthol, which then reacted with 1,2-ethanedithiol to be converted to
thiomethylated derivative. Direct thiomethylation of 2-naphthol and its acetate with formaldehyde
and 1,2-ethanedithiol is nonselective, because the reaction involves both О- and С-sp2 reaction
centers of the substrate. Binuclear copper complexes with Cu-O-Cu-N- or Cu-Cl-Cu-S bonds were
prepared.
Key words: aminomethylation, thiomethylation, 2-naphthol, 1,2-ethanedithiol, binuclear copper
complexes, 2-copper-1,3-oxazine
1. Introduction
2-Naphthol derivatives containing nitrogen and sulfur atoms are of interest as fluorescent
chemosensors,1 while copper complexes of 2-naphthol oligomers are applicable as photosensitive
semiconductors.2 It is known 3-5 that polyaromatic phenol derivatives containing copper oxazine
heterocycles exhibit antimicrobial, fungicidal, and antitumor activities.
There are examples for the synthesis of copper complexes based on imine containing
naphthols (Schiff bases), which have luminescent and magnetic properties.6 At the same time, zinc
complexes with iminonaphthol ligands have been studied as lactide polymerization catalysts.7
There is no information on complexes with sulfur-containing naphthol ligands. However, a
zirconium complex with sulfur-containing phenolic ligands is described which catalyzes the
polymerization of alpha-olefin.8
A rational synthesis of β-naphthol N-derivatives is based on catalytic aminomethylation
with formaldehyde and dimethylamine 9,10 or on the reaction of 2-naphthol with iminium reagents
catalyzed by Lewis acids.11-13 S-Derivatives of β-naphthol were prepared by thiomethylation of
1

the substrate 14 or by conversion of 1-triazolomethylated 2-naphthol under alkaline conditions to
thiomethyl 2-naphthol derivative.15
2. Results and Discussion
We have been developed a new approach to the synthesis of N- and S-ligands for the
binuclear Cu complexes of dimeric 2-naphthol derivatives based on successive α-СН-
functionalization of
β-naphthol. The method includes aminomethylation of β-naphthol 1 with
1-
N,N,N',N'-tetramethyldiaminomethane in the presence of 5 mol% K2CO3 catalyst to give
[(dimethylamino)methyl]-2-naphthol 2, which is then converted to sulfanylmethyl-substituted
product 3 by treatment with 1,2-ethanedithiol in glacial acetic acid or in acetic anhydride in the
presence of sodium citrate or acetate (20 mol%) as a catalyst (route а). The total yield of the target
product 3 is 63%.
CH3
CH3
N
a
route
CH3 CH3
O
O
S
N
N
HS
SH
CH3
OH
CH3
H3C
S
5 mol% K2CO3,
CHCl3, 60 oC
20 mol% NaOAc,
CH3COOH, 80 oC
OH
3
94%
63%
1
2
O
O
CH3
Sсheme 1. Synthesis of N- and S-derivatives of 2-naphthol via C(sp2)-aminomethylation
Apart from the replacement of amino group by a sulfide group, the reaction along pathway
a involves acylation of the 2-naphthol hydroxy group, which is to be expected in view of efficiency
of this acylation under the action of acetic acid in the presence of various catalysts.16 Evidently,
the dimethylamine substituent in compound 2 is a good leaving group under acidic conditions.17
Thus, the deamination-sulfanylation-acylation tandem reactions afford 1,2-bis[(2-acetoxynaphth-
1-yl)methylsulfanyl]ethane 3.
An alternative pathway to product 3 (route b) starting from 2-naphthol involves the
preparation of the acetoxy derivative 4, which is then thiomethylated with formaldehyde and
1,2-ethanedithiol. However, under these reaction conditions, the target product 3 is formed in a
mixture with oligomeric products.
b
route
CH2O +
20 mol% NaOAc, EtOH, 70 oC
HS
SH
OH
O
CH3
Ac2O / Py, r.t.
97%
3
+ mixture
O
53%
4
Sсheme 2. Thiomethylation of naphthalen-2-yl acetate with formaldehyde and 1,2-ethanedithiol
2

HO
c
route
O
O
CH2O +
HS
SH
S
S
OH
S
20 mol% NaOAc, EtOH, 70 oC
+
+
90%
S
S
S
OH
O
OH
5a
5b
5c
Sсheme 3. Thiomethylation of 2-naphthol with formaldehyde and 1,2-ethanedithiol
Direct С-sp2-thiomethylation of naphthol (route c) similar to multicomponent reaction of
dicarbonyl CH-acids18,19 with formaldehyde and 1,2-ethanedithiol in the presence of Lewis acids
does not proceed, whereas in the presence of bases (NaOAc, n-BuONa), the reaction
simultaneously follows the О- and С-sp2-thiomethylation pathways and gives a poorly separable
mixture of products 5a-с in 90% yield. The MALDI TOF/TOF mass spectrum of the obtained
mixture 5a-с exhibits ion peaks at m/z 429.1271 [M+Na]+ and 445.1107 [M+K]+, with the
theoretical М value being 406.1061. The 1Н and 13С NMR spectra show the signals for methylene
hydrogen and carbon atoms both between the sulfur and oxygen atoms (δН 4.75-5.00 ppm and δС
62-65 ppm) and between the sulfur atoms and the aromatic ring (δН 4.2 ppm and δС 31-37 ppm).
The N- and S-heteroatomic derivatives of naphthol 2 and 3 obtained by pathway а are
convenient precursors for the synthesis of Cu(II) and Cu(I) chelate complexes. Taking account of
the Pearson's hard and soft acids and bases (HSAB) concept,20 we performed the reaction of N-
containing β-naphthol ligand 2 as a borderline base with a Cu(II) salt, Cu2(OAc)4 · 2H2O
(borderline acid) at 50 °С. The S-containing ligand 3 as a soft base was reacted with Cu(I) salt,
Cu2Cl2 (soft acid) at 50 °С. Finally, we obtained Cu binuclear dimeric 2-naphthol adducts
containing the O,N-oxazinane 6 or S,S-dithiacyclane 7 moiety.
3

O
CH3
N
CH3
O
H3C
N
CH3
Cu O
.
1/2 Cu2(OAc)4 2H2O
OH
O Cu
O
EtOH, 60 oC
N
CH3
94%
H3C
O
O
2
H
H
6
O
O
CH3
O
S
CH3
Cu2Cl2
CH3CN : CHCl3, 60 oC
O
S
S
Cl
92%
S
O
Cu
Cu
H3C
3
Cl
O
O
7
H3C
O
Sсheme 4. Synthesis of binuclear Cu(II) and Cu(I) complexes
The structures of compounds 2-4, 7 and 5 as a regioisomeric mixture of 5a-c were
established by means of 1Н and 13С NMR spectroscopy and mass-spectrometry. Compounds 2, 3,
and 6 were studied by X-ray diffraction (Fig. 1-3). As can be seen in Fig. 1, in the molecule 2, a
5,6-dehydro-1,3,2-oxazahydrane pseudo-ring is formed via hydrogen bonding.
а
b
Fig. 1. а) Molecular structure of compound 2, with non-hydrogen atoms represented by thermal
ellipsoids (р=50%); b) molecular packing in the crystal along the а axis.
The asymmetric unit of compound 3 contains one-half of the molecule (Z’ = 0.5): a
crystallographic center of inversion is located at the midpoint of the central C16–C16 bond. In the
crystal of compound 3, the acetoxynaphthyl substituents are anti-oriented relative to the
ethanedisulfanyl bridge (Fig. 2a). The acetate and naphthalene moieties occur in different planes;
4

the dihedral angle is 57.86(18)°. In the crystal, molecules of 3 are linked into stacks along b axis
by non-classical C–H...O hydrogen bonds (Fig. 2b).
а
b
Fig. 2. a) Molecular structure of compound 3, with non-hydrogen atoms represented by thermal
ellipsoids (р=50%); b) molecular packing in the crystal along the b axis.
The crystal of metallaheterocycle 6 contains a planar 2,4-dicupra-1,3-dioxetane ring and
two non-planar dioxazinane rings (Fig. 3а.). Compound 6 crystallizes with two independent
species having the similar molecular geometry and linking by O–H…O hydrogen bonds with the
water molecule (Fig. 3b). The coordination environment of copper atoms is formed by N8 (N11)
nitrogen atoms and two oxygen atoms, O2 (O1) of the 1-[(dimethylamino)methyl]-2-naphtol
ligand and the О4 (О3) oxygen atoms of the acetate ligand. The Cu1–О2 bond lengths in I are
1.978(18) and 1.952(3) Å, and the Cu2–О1 bonds in II are 1.990(2) and 1.959(2) Å. The difference
between the Cu–О bonds indicates asymmetry of the bridge formed by naphthol oxygen atoms.
The monodentate coordination via the acetate ion is confirmed by unequal С–О bond lengths (in
the molecule I, С17–О4 =1.274(5) Å and С17–О10 = 1.225(4) Å; in the molecule II, С14–О3 =
1.266(4) Å and С14–О13 = 1.228(4) Å. The О10 and О13 oxygen atoms of the acetate ligands
participate in the formation of the О–Н…О hydrogen bonds with a water molecule (Fig. 3b, see
Supplementary Information). The Cu2–О3 and Cu2–N11 bond lengths in II are 1.930(3) and
2.024(3) Å, respectively, whereas the lengths of analogous bonds (Cu1–О2 and Cu1–N8) in the
molecule I differ insignificantly, being 1.952(3) and 2.030(3) Å.
5

а
b
Fig. 3. а) Molecular structure of the binuclear copper complex hydrate 6 (LCuOAc)2·H2O, with
non-hydrogen atoms represented by thermal ellipsoids (р=50%). The numbering of non-hydrogen
atoms is given for the molecule II; b) ball-and-stick model of two independent molecules in the
crystals of compound 6
The UV spectra of complex 6 exhibit a shoulder at λ 644.52 nm, which is absent in the
spectrum of ligand 3, while the characteristic peaks in the 260–340 nm range are retained and
become diffuse. In the IR spectrum of copper complex 6, in comparison with the spectrum of
ligand 3, long-wavelength absorption bands appear at ν 303, 333 cm-1(Сu-O) and characteristic
band for the Cu-O bond with phenolic oxygen atom appears at ν 553 cm-1.21 The ESI mass
spectrum shows a peak for the[M+H-C15H16CuNO3]+ ion (m/z 342.1), which is formed upon
cleavage of two Cu-ONaphthyl-2 coordination bonds in the central dicupradioxetane ring of the
molecule 6, with the cupraoxazine ring being retained. The ESI mass spectrum of compound 7
shows characteristic peaks of the [M+H+H2O-CH3CO2H]+ ions at m/z 645.2 and [M-CuCl2]+ ions
at m/z 553.2. The MALDI TOF/TOF mass spectrum of complex 7 also exhibits an ion formed by
elimination of the acyl group [M-CH3CO] + at m/z 642.9378 (calculated M 685.9241); phenol
esters typically eliminate the acyl ion CH3CO + with m/z 43.22 In the UV spectrum of compound
1
13
7, a shoulder appears at λ 408.01 nm. In the H and C NMR spectra, the set of the proton and
carbon signals of the ligand in the complex 7 was identical to that for the molecule 3. But the 1Н
NMR spectrum of 7 shows broadened proton signals, unlike the corresponding singlets of the
precursor 3. In the IR spectrum of compound 7, the absorption bands in the 291-326 cm-1 region
are related to the vibrations of the Сu–S bonds (see Supplementary Information). Taking into
account the spectral data, the two copper atoms in the molecule 7 are combined via bridging
chlorine atoms, similarly to the structure formed upon the complexation between bis-
isoxazolylmethylsulfanylethane and Cu(I) halides.23
6

The EPR spectrum of complex 6 recorded at 293 K in CHCl3 solution is typical of
copper(II) species6 and have a quartet due to coupling of the Cu2+ ion having S = 3/2 (Fig. 4). The
separation of the peaks (in Gauss) is caused by the hyperfine coupling of two isolated Cu2+ ions.
The isotropic g-value and linewidth ΔB have been identified (Table S10 see Supplementary
Information).
Fig. 4. EPR spectrum of compound 6 recorded in CHCl3 solution at 293 K using DPPH
as the standard
Conclusion
Thus, we have found that the rational approach to the preparation of N- and S-ligands for
binuclear copper complexes involves the two-step transformation of 2-naphthol, including С-sp2-
aminomethylation of 2-naphthol (N-ligand for Cu(II) complex) and its subsequent transformation
to the thiomethylated derivative under the action of thiol (S-ligand for Cu(I) complex). The
structural features of the synthesized copper complexes may be of interest as cytostatics of
malignant tumors, about which a separate communication is planned.
3. Experimental section
4.1 General information
All reagents used in the work, were purchased from Sigma-Aldrich (Steinheim, Germany)
and Acros Organics (Geel, Belgium).
Mass spectra of compounds 2, 3, 4 and 6 were recorded on a Bruker MALDI TOF/TOF
Autoflex III instrument. The electrospray ionization mass spectra (ESI) of products 6 and 7 were
obtained on an LCMS-2010 EV instrument (Shimadzu) (syringe injection of the sample, eluent
acetonitrile/water (85:15), flow rate 0.1 mL/min) at a capillary potential of 4.5 kV , at a heater and
evaporator temperature of 200 and 230° C, a spray gas (nitrogen) flow rate of 1.5 L/min. IR spectra
of complexes 6,7 and their ligands were recorded on a Bruker Vertex-70V Fourier spectrometer
in liquid paraffin. IR spectra of organic products were recorded on a Bruker Vertex-70V FTIR and
Specord M80 spectrometers in suspension Nujol. 1H, 13C NMR spectra were recorded on a Bruker
7

Avance III HD 500(400) spectrometer (500, 125 MHz). Solvent CDCl3 (DMSOd6), internal
1
13
standard for H and C NMR spectra — two-dimensional experiments were performed using
standard pulse sequences from Bruker. Melting points were determined on a RNMK 80/2617
device (Kofler table). Monitoring of the reaction was carried out by TLC on Sorbfil plates, the
manifestation of iodine vapor.
The X-ray diffraction measurements for compounds 2, 3 and 6 were performed on
an Agilent XCalibur (Eos, Gemini) automated four-circle diffractometer (graphite
monochromator, MoKα radiation, λ = 0.71073 Å, ω-scan mode, 2θmax = 62°) at ambient
temperature (293–298 K). Collected data were processed using the program CrysAlisPro.24
The structures were solved by direct methods and refined by the full-matrix least-squares
method in the anisotropic approximation for non-hydrogen atoms. The calculations were
performed using the SHELX program package.25 All hydrogen atoms in compounds 3 and
6 were generated using the proper HFIX command and refined isotropically using the
riding model. The hydrogen atoms in compound 2 were located in the Difference Fourier
map and refined isotropically. The EPR spectra were registered using spectrometer Bruker EMX
plus 10/12 with X-diapason (Bruker Co., Ltd, Germany, ~9.45 GHz) at 293 K (the diameter of the
quartz ampoules equals 4 mm). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) was used as a standard.
1-[(Dimethylamino)methyl]-2-naphthol (2). A mixture of 0.3 g (2 mmol) of 2-naphthol
and 0.33 mL (2.5 mmol) of N,N,N',N'-tetramethyldiaminomethane and 5 mol% K2CO3 in 5 mL
CHCl3, was stirred at a 60 °C for 4 h. The resulting solution was evaporated on rotary evaporator.
Yield 0.37 g, 94%, transparent prismatic crystals, m.p. 74-76 °C. IR spectra, , сm-1: 3202, 3129,
1
3100, 2974, 2443, 1669, 1252, 1174, 1143, 1096, 1014, 843, 718, 611. Н NMR (500.13 MHz,
DMSOd6):  = 2.29 (s, 6Н, СН3), 3.99 (s, 2Н, СH2), 7.06 - 7.95 (m, 1Н, СНAr), 8.33 (s, 1Н, OН).
13С NMR (124.78 MHz, DMSOd6):  = 44.79 (CH3), 55.95 (CH2), 113.41, 118.93, 122.70, 126.58,
128.39, 128.78, 129.15, 133.41 (CAr), 155.86 (C-OH). MALDI TOF/TOF: m/z (%): 201.1137 [M]
+, M (mass calculated) 201.1154. C13H15NO.
1,2-Bis[(2-acetoxynaphth-1-yl)methylsulfanyl]ethane (3). Route a. A mixture of 0.4 g
(2 mmol) of 1-[(dimethylamino)methyl]-2-naphthol 2 in 5 mL of glacial acetic acid (or acetic
anhydride) and 20 mol% sodium acetate were loaded into the reactor, then 0.17 mL (2 mmol) 1,2-
ethanedithiol was added portionwise. The reaction mass was stirred at 80 °C for 6 h in an argon
atmosphere. The resulting solution was cooled to room temperature and evaporated on a rotary
evaporator. Obtained the residue (0.66 g), which was purified on SiO2, eluent: Hex-EtOAc-CHCl3,
1: 2: 1, isolating 0.2 g (Rf 0.64) of ethanedithiol acetate and 0.33 g (Rf 0.06) of product 3, yield
63%, transparent prismatic crystals, m.p. 180-182 °C. IR spectra, , сm-1: 1765, 1195, 1012, 970,
8

812, 739. 1Н NMR (500.13 MHz, CDCl3):  = 2.33 (s, 6Н, СН3), 2.75 (s, 4Н, СH2), 4.11 (s, 4Н,
СH2), 7.20 - 8.08 (m, 12Н, СНAr). 13С NMR (124.78 MHz, CDCl3):  = 21.02 (CH3), 26.57 (CH2),
32.26 (CH2), 121.46, 124.06, 125.71, 126.85, 128.78, 128.98, 132.09 (CAr), 146.54 (C-O),
169.48(C=O). MALDI TOF/TOF: m/z (%): 513.1094 [M+Na] +, 529.0845 [M+K]+. m/z (mass
calculated) 490.1273. C28H26O4S2.
Route b. A mixture of 0.17 mL (2 mmol) of 1,2-ethanedithiol and 0.3 mL (4 mmol) of a
37% formaldehyde solution in water was stirred at room temperature for 40 min. Next 0.74 g (4
mmol) of naphthalene-2-yl acetate 4 in 5 mL of alcohol (EtOH or i-PrOH) was added. It was stirred
at 70-80 °C for 6 h and cooled. The precipitate was filtered and washed with MeOH, air dried. It
was received 0.52 g of a mixture of product 3 with oligomers.
Naphthalen-2-yl acetate (4). A mixture of 1.44 g (10 mmol) of 2-naphthol and 3 mL of
acetic anhydride in 5 mL of pyridine was loaded and stirred at room temperature for 5 h. The
resulting solution was evaporated on a rotary evaporator. It was extracted with methylene chloride
and dried over CaCl2. It was received 1.80 g, yield 97%, amorphous white powder, m.p. 72-74
°C. 1Н NMR (500.13 MHz, CDCl3):  = 2.39 (s, 3Н, СH3), 7.26-7.90 (m, 7Н, СНAr). 13С NMR
(124.78 MHz, CDCl3):  = 21.23 (CH3), 118.56, 121.16, 125.74, 126.59, 127.67, 127.80, 129.44,
131.49, 133.78 (CAr), 148.36 (C-O), 169.68 (C=O). MALDI TOF/TOF: 186.0854 [M]+ m/z (mass
calculated) 186.0681. C12H10O2.
O- and C(sp2)-thiomethylation of 2-naphthol with the formation of a mixture of
products (5а-с). Route c. A mixture of 0.17 mL (2 mmol) of 1,2-ethanedithiol and 0.3 mL (4
mmol) of a 37% formaldehyde solution in water was stirred at room temperature for 40 min. Then
0.57 g (4 mmol) of naphthol-2 in 5 mL of alcohol (EtOH or i-PrOH) and 20 mol% sodium acetate
were added. Stirred at 70-80 °C for 6 h and cooled. The resulting solution was evaporated on a
rotary evaporator. The mixture of products was obtained as amorphous white powder, 0.73 g,
1
yield 90%. IR spectra, , сm-1: 3435, 1621, 972, 813, 743. Н NMR (500.13 MHz, CDCl3):  =
2.82 (s, 4Н, СH2), 3.42 - 4.93 (m, 4Н, SСH2Ar or SСH2O), 7.21-8.25 (m, 12Н, СНAr), 9.92 (s,
1Н, OН). 13С NMR (124.78 MHz, CDCl3):  = 26.57 (CH2), 31.41, 32.58 (CH2Ar), 62.53, 65.22
(CH2O) 121.46, 124.06, 125.71, 126.85, 128.78, 128.98, 132.09 (CAr), 146.54 (C-O). MALDI
TOF/TOF: 429.0831 [M+Na]+, 445.0213 [M+K]+. М (mass calculated) 406.1061. C24H22O2S2.
N,O-Binuclear monohydrate copper(II) acetato complex with 1-[(dimethylamino)
methyl]-2-naphthol (6). A mixture of 0.4 g (2 mmol) of 1-[(dimethylamino)methyl]-2-naphthol
2 and 0.4 g (2 mmol) of copper(II) acetate monohydrate in 5 mL ethanol was stirred at 60 °C for
3 h. The resulting solution was evaporated on rotary evaporator. The precipitate was washed
with water, dried and recrystallized from a mixture of CHCl3 - EtOH (1:1). It was obtained 0. 55
9

g of 6, yield 94%, prismatic green crystals, m.p.150-152 °C. IR spectra, , сm-1: 1568, 1462,
1377,1270, 1011, 843, 733, 610, 483, 340, 304. UV (СHCl3) 279.64, 292.94, 320.11, 644.52. М
(mass calculated) 662.1114. ESI, m/z (%): 342.1 [M+H-C15H16CuNO3]+.
S-Binuclear
chlorocomplex
copper(I)
with
1,2-bis[(2-acetoxynaphth-1-
yl)methylsulfanyl]ethane (7). A mixture of 0.49 g (1 mmol) 1,2-bis[(2-acetoxynaphth-1-
yl)methylsulfanyl]ethane 3 and 0.20 g (1 mmol) of copper(I) chloride in 10 mL of a mixture of
chloroform-acetonitrile (1:1) was stirred in an argon atmosphere at 60 °C for 5 h. The resulting
solution was evaporated on rotary evaporator. The solid residue was washed with acetonitrile,
dried, obtaining 0.63 g of 7. Yield 92%, white powder, m.p. 90-92 °C. IR spectra, , сm-1: 1766,
1195, 1010, 971, 812, 738, 326, 322, 316, 307, 302, 301, 291. 1Н NMR (500.13 MHz, DMSOd6):
 = 2.23 (b.s, 6Н, СН3), 2.76 (b.s, 2Н, СH2), 4.14 (b.s, 2Н, СH2), 7.22, 7.47, 7.82, 8.08 (m, 12Н,
13
СНAr). С NMR (124.78 MHz, DMSOd6):  = 21.31 (CH3), 26.65(CH2), 32.5 (CH2), 122.38,
124.71, 126.12, 127.22, 128.95, 131.91 (CAr),146.95 (C-O), 169.77(C=O). MALDI TOF/ TOF m/z
(%): 642.937 [M-CH3CO]+. М (mass calculated) 685.9241. ESI, m/z (%): 645.2 (13) [M+H+H2O-
CH3CO2H]+, 553.2 (100) [M -CuCl2]+.
Single crystals of 2 were grown from CHCl3 and studied on an Agilent XCalibur (Eos,
Gemini). All crystallographic calculations were conducted using SHELX.25 The crystal structure
was generated by using Mercury.26
Crystal data for 2. C13H15NO, M = 201.26, monoclinic, P21/n (no.14), a = 8.0076(5) Å, b =
16.7555(9) Å, c = 9.1398(7) Å, α = 90°, β = 112.771(8)°, γ = 90°, V = 1130.72(14) Å3; Z = 4; T =
293(2) K; μ(MoKα) = 0.075 mm-1, Dcalc = 1.182 g/сm3; reflections collected = 5098, independent
reflections = 2600 (Rint = 0.0227), final R indexes [I > 2σ(I)]: R1 = 0.0558, wR2 = 0.1169. R indexes
(all data): R1 = 0.0952, wR2 = 0.1395, GOF = 1.008. CCDC 1909255 contains the supplementary
crystallographic data for compound 2. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
Single crystals of 3 were grown from CHCl3. Crystal data for 3. C28H26O4S2, M = 490.61,
monoclinic, P21/c (no.14), a = 11.531(4) Å, b = 4.7014(12) Å, c = 22.952(8) Å, α = 90°, β =
102.17(3)°, γ = 90°, V = 1216.3(7) Å3; Z = 2; T = 293(2) K; μ(MoKα) = 0.252 mm-1, Dcalc
=
1.340 g/сm3; reflections collected = 5056, independent reflections = 2791 (Rint = 0.1018), final R
indexes [I > 2σ(I)]: R1 = 0.0915, wR2= 0.1884. R indexes (all data): R1 = 0.2296, wR2= 0.2506,
GOF = 0.901. CCDC 1909259 contains the supplementary crystallographic data for compound 3.
These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/getstructures.
Single crystals of 6 were grown from CHCl3/MeOH. Crystal data for 6. C30H36Cu2N2O7,
M = 663.71, triclinic, P-1 (no.2), a = 10.3873(6) Å, b = 12.3323(7) Å, c = 13.9121(6) Å, α =
10

103.241(4)°, β = 101.692(4)°, γ = 114.382(6)°, V = 1488.62(15) Å3; Z = 2; T = 293(2) K;
μ(MoKα) = 1.477 mm-1, Dcalc = 1.481 g/сm3; reflections collected = 12521, independent
reflections = 6856 (Rint = 0.0377), final R indexes [I > 2σ(I)]: R1 = 0.0452, wR2= 0.0726. R indexes
(all data): R1 = 0.1016, wR2= 0.0838, GOF = 0.882. CCDC 1885553 contains the supplementary
crystallographic data for compound 6. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
Funding Information
This work was supported by the Russian Foundation for Basic Research and the Academy of
Sciences of the Republic of Bashkortostan (project No. 17-43-020292р_а), by the Russian
Ministry of Education and Science (project No. 2019-05-595-000-058), by grant of the Republic
of Bashkortostan to young scientists (2020) and within the framework of the State Assignment
AAAA-A19-119022290010-9
Acknowledgment
The results were obtained on unique equipment at the “Agidel” Collective Usage Center (Ufa
Federal Research Center, Russian Academy of Sciences). EPR spectra were recorded using the
equipment of CCU “Spektr” (Dr. Yu. A. Lebedev, IMCP, UFRC of RAS)
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12

Highlights
The rational approach to the preparation of N- and S-ligands for novel binuclear copper complexes
involves the two-step transformation of 2-naphthol, including С-sp2-aminomethylation of 2-
naphthol (N-ligand for Cu(II) complex) and its subsequent transformation to the thiomethylated
derivative under the action of thiol (S-ligand for Cu(I) complex).
13

Graphical Abstract
Synthesis of Novel N- and S-Derivatives of 2-Naphthol - Promising Ligands
for the Binuclear Copper Complexes
Vnira R. Akhmetova, El'mira M. Bikbulatova, Ekaterina S. Mescheryakova, Nail S.
Akhmadiev, Marat F. Abdullin, Askhat G. Ibragimov
An original approach to the synthesis of binuclear copper complexes with Cu–N and Cu–S bonds
is proposed via functionalization of 2-naphthol.
Me
O
H
H
N
O
Me
Me
Me
Cu
OH
1/2 Cu2(OAc)4 . 2H2O
C2H5OH, 60 o
N
O
O
Me
C
O
Cu
Me
O
Me
N
SH
HS
Me
O
20 mol% CH3COONa
O
O
Me
O
CH3COOH, 80 o
C
Me
O
Cu2Cl2
CH3CN : CHCl3, 60 o
C
S
S
S
S
Cl
Cl
O
O
Cu
Cu
Me
O
Me
O
14

All authors individual contributions
Vnira R. Akhmetova – Conceptualization. Data curation. Management activities to annotate
(produce metadata), scrub data and maintain research data. Writing- Original draft preparation and
creation of the published work.
El'mira M. Bikbulatova – Conducting research and investigation of aminomethilation process and
complexation, specifically performing the experiments. Methodology.
Ekaterina S. Mescheryakova – X-ray analysis, testing of existing code components using the
computer.
Nail S. Akhmadiev – Investigation of thiomethilation reactions. Methodology.
Marat F. Abdullin– МS analysis, implementation of the computer code and supporting algorithms.
Askhat G. Ibragimov – Oversight and leadership responsibility for the research activity planning
and execution.
15