New tripodal ligand on the triphenylphosphine oxide platform with 1,2,3-triazole side arms: synthesis, structure, coordination, and extraction properties

Article abstract of DOI:10.1007/s00706-020-02702-6

Abstract: New hybrid tripodal propeller ligands on the triphenylphosphine oxide platform with triazole rings in the side arms and alkyl and aryl substituents in the triazole fragments have been synthesized by the click reaction. Composition and structure of the prepared compounds have been established by vibrational (IR, Raman) and multinuclear (¹H, ¹³C, ³¹P) NMR spectroscopy, elemental analysis, and mass spectrometry. Coordination and extraction properties of the prepared compounds toward Pd(II) have been studied by the example of one of the ligands. Graphic abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s00706-020-02702-6

Monatshefte für Chemie - Chemical Monthly
https://doi.org/10.1007/s00706-020-02702-6
ORIGINAL PAPER
New tripodal ligand on the triphenylphosphine oxide platform
with 1,2,3‑triazole side arms: synthesis, structure, coordination,
and extraction properties
Igor Y. Kudryavtsev1 · Olga V. Bykhovskaya1 · Anna G. Matveeva1 · Tatyana V. Baulina1 · Margarita P. Pasechnik1 ·
Sergey V. Matveev1 · Anna V. Vologzhanina1 · Alexander N. Turanov2 · Vasilii K. Karandashev3,4 · Valery K. Brel1
Received: 31 July 2020 / Accepted: 30 September 2020
© Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract
New hybrid tripodal propeller ligands on the triphenylphosphine oxide platform with triazole rings in the side arms and alkyl
and aryl substituents in the triazole fragments have been synthesized by the click reaction. Composition and structure of the
prepared compounds have been established by vibrational (IR, Raman) and multinuclear (1H, 13C, 31P) NMR spectroscopy,
elemental analysis, and mass spectrometry. Coordination and extraction properties of the prepared compounds toward Pd(II)
have been studied by the example of one of the ligands.
Graphic abstract
Keywords Click reaction · Extraction · 1,2,3-Triazole · Tripodal ligands · Palladium complex · X-ray structure
determination
Introduction
Electronic supplementary material The online version of this
Versatile architecture of tripodal ligands based on central
article (https://doi.org/10.1007/s00706-020-02702-6) contains
core (platform) and three side arms containing functional
groups provides a possibility to construct various hosts of
diferent denticity and geometry [1, 2]. Depending on the
nature of functional groups, tripodal ligands can form com-
plexes with cations [3–6], anions [7–10], and neutral mol-
ecules [11–13]. These ligands are used for recovery of d- and
f-block elements and separation of actinides and lanthanides
[10, 14–18]. At the same time, there is growing interest in
tripodal ligands based on the triphenylphosphine oxide
platform [19–22]. Due to structural features, these ligands
adopt a propeller conformation, where the side chains in the
ortho position with donor groups come close to each other
supplementary material, which is available to authorized users.
* Igor Y. Kudryavtsev
zaq@ineos.ac.ru
1
Nesmeyanov Institute of Organoelement Compounds,
Russian Academy of Sciences, Moscow, Russia
2
Institute of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
3
Institute of Microelectronics Technology Problems
and High Purity Materials, Russian Academy of Sciences,
Chernogolovka, Russia
4
National University of Science and Technology MISiS,
Moscow, Russia
Vol.:(0123456789)
1 3

I. Y. Kudryavtsev et al.
and the central P=O group to form a cavity favorable for
complexation with metal cation. These ligands containing
C=O and C≡N groups in the side chains produce complexes
with d- and f-block elements [19–22] and behave as efcient
extractants for actinides and lanthanides [21, 22]. Design-
ing polydentate ligands containing donor atoms of difer-
ent nature and showing diverse afnity to diferent types of
cations is the promising direction of tripodal ligands devel-
opment. For example, the combination of N and O centers
may provide ligand selectivity [23]. It is known that ligands
containing 1,2,3-triazole fragments produce complexes with
metal ions [24–26]. In this context, 1,2,3-triazole fragments
are promising candidates to include in the side chains of
tripodal ligands based on the triphenylphosphine oxide plat-
form. Approaches to the synthesis of 1,2,3-triazoles are well
developed [26–29]. Ligands containing 1,2,3-triazole frag-
ments are known to form stable complexes with PdCl2 [24,
30–33], compounds with these fragments recover palladium
from aqueous solutions [34–36].
The aim of this work is to synthesize new tripodal N,O-
donor ligands 1–6 based on the triphenylphosphine oxide
platform with 1,2,3-triazole fragments in the side chains
(Fig. 1) and to study their coordination and extraction prop-
erties toward palladium(II) by the example of compound 1.
Results and discussion
The target phosphine oxides 1–6 were prepared by the fol-
lowing general scheme (Scheme 1). Initial triphenyl phos-
phate was treated with lithium diisopropylamide (LDA) to
give tris(2-hydroxyphenyl)phosphine oxide as a core com-
pound. The reaction of the latter with 2-chloroethanol under
alkaline conditions led to the corresponding hydroxyethyl
derivative, which was converted via two stages into triazide
7 (the preparation of compound 7 was reported previously
[37]). The click reaction of triazide 7 with the appropri-
ate acetylenes in the presence of CuBr catalyst resulted in
the target ligands 1–6 in good yields. The structure of the
obtained compounds 1–6 was confrmed by H, 13C, 31P
1
NMR and IR spectroscopy, while the structure of compound
Fig. 1 Tripodal ligands 1–6. R: 1, Ph; 2, 4-MeC6H4; 3, 4-MeOC6H4;
4, 4-t-BuC6H4; 5, n-Bu; 6, n-C6H13
1 was established by X-ray crystallography.
Scheme 1
1 3

New tripodal ligand on the triphenylphosphine oxide platform with 1,2,3-triazole side arms:…
angle between meanplanes of the N7–N8–N9–C41–C42 and
the C1–C2–C3–C4–C5–C6 rings is equal to 11.7(1)°, and
intercentroid distance is equal to 3.99(2) Å. Intermolecular
bonding includes C–H…N and C–H…π interactions; and the
molecules packed so that solvent molecules (removed using
SQUEEZE procedure) form infnite channels parallel with
the crystallographic axis c (Fig. S2, ESI).
Let us note that the P=O bond (1.500(6) Å) is longer
than that in the related 2-substituted triarylphosphine
oxides containing no hydrogen bonds (for example, 1.485
Å in [2-Bu2NC(O)CH2OC6H4]3P(O) and 1.486 Å in
[2-Me2NC(O)CH2OC6H4]3P(O) [21], but almost the same
as in ligands, where P = O group is involved in hydrogen
bonding: 1.502 Å for Ph2P(O)CH2CH2CH(OH)Me [42],
1.503 Å for [2-HO(CH2)2OC6H4]3PO [41], 1.513 Å for
(HOCH2CH2CH2)3PO [43]. The IR spectrum of crystal-
line phosphine oxide 1 shows absorption of the phosphoryl
group ν(P=O) as a shoulder at about ~ 1175 cm−1, which
is slightly lower than for related compounds producing no
intramolecular H-bond [21]; the band ν(C–H) is broad with
a weak maximum at~3130 cm−1, which agrees well with the
formation of intramolecular hydrogen bonds C–H∙∙∙O=P
as revealed by X-ray difraction. In the IR spectrum of solid
compound 1, a weak band at 1563 cm−1 (ν(C=C)) and
medium-intensity band at 1037 cm−1 (ring deformation) can
be related to triazole ring vibrations. The Raman spectrum
proved to be more informative for the characterization of
triazole rings: observed lines at 1555, 1358, and 1229 cm−1
may be referred to vibrations of the triazole rings by com-
parison with spectra of related compounds [44].
Fig. 2 Molecular view of compound 1 in representation of atoms
with thermal ellipsoids (p=50%). Intramolecular hydrogen bonds are
depicted with dashed line
The molecule structure in crystals of ligand 1 has asym-
metrical propeller conformations (Fig. 2). Two of the three
ortho OCH2 substituents are oriented to the same direction
as the P=O group, while the third substituent is oriented to
the opposite direction. Bond distances and angles of ligand
1 (Table S1, ESI) are typical for related tripodal ligands with
diferent functional groups in the side arms reported earlier
[21, 38–41]. All these compounds have the 2-UP conforma-
tion. In this conformation, two of three ortho substituents
are oriented to the same direction as the P=O group, while
the third substituent is directed to the opposite side. For
compound 1, the O1–P1–C18–O3 angle of -171.83(2)° cor-
responds to the “arm” situated on the opposite side toward
the vector of P=O bond, and two other “arms” are located
on the same side as P=O phosphine oxide in respect to the
carbon atoms of POC3 moiety with O–P–C–O angles equal
to ca. 55°. In the tripodal ligands with hydroxyl [41] and
tetrazole groups in the side arms [39], such conformation is
additionally supported by two intramolecular O–H…O=P
or N–H…O=P interactions, respectively. While three intra-
molecular C–H…O=P bonding in ligand 1 can be found
with hydrogen atoms of two “arms” situated on the same
side as the P=O group (Fig. 2). The C12–H…O1 bond
between the phosphoryl group and the phenyl ring is as short
as 3.68(1) Å (for the C…O distance); the C–H…O angle
is 175.6(1)°. The C9–H…O1 distance is characterized by
r(C…O)=3.39(1) Å and C–H…O angle of 166.2(2)°. The
C41–H…O1 distance is characterized by r(C…O)=3.68(1)
Å and C–H…O angle of 130.4(2)°. Moreover, one can pro-
pose intramolecular π-stacking interaction between a ben-
zene and a triazole rings of these arms (Fig. S1, ESI). The
The IR spectra of the other obtained compounds are simi-
lar to that of ligand 1 (Table 1) which confrm their struc-
tures. Thus, the spectra of all compounds show ν(PO) bands
at about~1176 cm−1, ν(C–H) bands at 3120–3133 cm−1 are
broadened or split. One can suppose that in solid state in
all obtained compounds, like in 1, C–H protons produce
contacts with either phosphoryl oxygen or other proton
acceptors. Vibrations of double bonds of the triazole ring
are characterized by the bands of different intensity at
1551–1560 cm−1.
Table 1 Analytically important IR absorption bands of solid com-
pounds 1–6 (̄ꢀ /cm−1; KBr disk)
Compound
ν(P=O)
ν(C–H)
Vibration of
triazole moiety/
cm−1
1
2
3
4
5
6
~1175m, sh
1176m
1175m
1179m
1176m
~3130w, sh
3130w, 3128w
3132w
3132w, sh
3120w
1560vw
1560vw
1560 m
1560w
1551w, 1530w
1551w
1176m
3123w
1 3

I. Y. Kudryavtsev et al.
The structure of the obtained compounds 1-6 was con-
extraction of Pd(II) with solutions of compound 1 in DCE
is shown in Fig. 4.
1
frmed also by H, 13C, and 31P NMR spectroscopic data.
1
The H and 13C NMR spectra of these compounds show
The extraction efciency was found to decrease as [HCl]
increases. Furthermore, the dependence of DPd upon [H+] at
a fxed concentration of Cl– ions was studied. As shown in
Fig. 5, variation of [H+] did not afect the Pd(II) extraction
with compound 1. On the other hand, an increase in [Cl–]
at a fxed concentration of H+ leads to decrease of the DPd
values (Fig. 6).
signals typical for a triazole fragment. The 1H NMR spectra
of compounds 1–6 show singlet signals with δH at 8 ppm
for compounds 1–4 (R=Ar) and at 7 ppm for compounds 5,
6 (R=Alk) corresponding to the C–H proton of the triazole
ring. Other proton signals are in the expected regions. The
13C NMR spectra of compounds 1–6 display singlet signals
at δC in the regions 122–123 ppm (CH) and 147–148 ppm
(–C=) indicating the presence of –C=CH– fragment of the
triazole ring. Other carbon resonances correspond to values
typical for related compounds [37, 41].
In the extraction systems with compound 1, the plot of
logDPd vs. log[Cl–] exhibited a straight line with a slope
close to −2, which means that two Cl– ions were released in
By the example of compound 1, we studied the extraction
of Pd(II) from hydrochloric acid solutions into 1,2-dichlo-
roethane (DCE) and the possibility of complex formation
with PdCl2.
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Liquid–liquid extraction of Pd(II) with compound 1
from HCl solutions
To determine efciency of Pd(II) recovery, we calculated the
distribution ratios (DPd =[Pd]org/[Pd]aq) and extent of palla-
dium recovery (E%=[Pd]org/[Pd]init·100%). The dependence
of E% on the concentration of HCl in the aqueous phase is
shown in Fig. 3. Recovery extent from aqueous solutions
reaches 90–99% palladium at acid concentrations below
0.5 M. However, recovery efficiency sharply decreases
at HCl concentration higher than 2 M. This is due to the
high stability of [PdCl4]2– complexes in the aqueous phase.
The efect of HCl concentration in aqueous phase on the
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
log[HCl]
Fig. 4 Efect of HCl concentration in aqueous phase on the extrac-
tion of Pd(II) with 0.001 M solution of compound 1 in DCE. Exp.
data black square, solid line: linear regression (R=0.999). Calculated
slope value is −2.08 0.04
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
log[H+]
Fig. 5 Efect of [H+] concentration in aqueous phase on the extrac-
tion of Pd(II) with 0.001 M solutions of compound 1 in DCE. Con-
centration of [Cl−] is 0.5 M. Exp. data black square, solid line: linear
regression (R=0.996)
Fig. 3 Dependence of E% on the concentration of HCl in the aque-
ous phase for Pd(II) extraction with 0.001 M solution of compound 1.
Exp. data black square
1 3

New tripodal ligand on the triphenylphosphine oxide platform with 1,2,3-triazole side arms:…
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-3.8
-3.6
-3.4
-3.2
-3.0
-2.8
-2.6
-2.4
-0.8
-0.7
-0.6
-0.5
-0.4
log[Cl-]
-0.3
-0.2
-0.1
0.0
log[L]
Fig. 7 Efect of extractant 1 concentration in DCE on the extraction
of Pd(II), from 1.0 M HCl solution. Exp. data black square, solid line:
linear regression (R=0.999). Calculated slope value is 1.49 0.03
Fig. 6 Efect of [Cl−] concentration in aqueous phase on the extrac-
tion of Pd(II) with 0.001 M solutions of compound 1 in DCE. Con-
centration of [H+] is 0.1 M. Exp. data black square, solid line: linear
regression (R=0.999). Calculated slope value is −1.98 0.02
According to available literature data on the structure of com-
plexes of substituted 1,2,3-triazoles with PdCl2 [24, 30–33],
one can suppose that ligand 1 is coordinated in the complex
with composition Pd:L=1:1 in an N,N-bidentate mode, while
both ligand molecules in the 1 : 2 complex are coordinated in
N-monodentate mode. To verify this assumption, we prepared
the complex of composition Pd:L=1:1.
the extraction reaction. When [HCl]>0.1 M, Pd(II) prefera-
bly exists in aqueous solutions as [PdCl4]2– anion. Therefore,
Pd(II) is extracted into organic phase as [PdCl2Ls]0 complex
(where s is a Pd:L stoichiometric ratio) via the substitution
of two Cl– ions in [PdCl4]2– anion by s coordinated mol-
ecules of ligand L.
The stoichiometric ratio of palladium(II) to extractant in
the extracted complexes was determined by the slope analy-
sis method. The variations in DPd as a function of compound
1 concentration in DCE are shown in Fig. 7. At constant
composition of the aqueous phase, the slope of dependence
logDPd vs. log[L] is close to 1.5, which corresponds to Pd(II)
transfer into organic phase as neutral complexes of composi-
tion [PdLCl2]0 and [PdL2Cl2]0.
Complexation of ligand 1 with PdCl2
The reaction of stoichiometric amounts of PdCl2(NCPh)2 with
1 in acetonitrile resulted in the formation of a precipitate. The
composition of the resultant compound 8 according to elemen-
tal analysis and vibrational spectroscopy (vide infra) corre-
sponds to [PdCl2(1)]·3H2O (Scheme 2). The complex is insol-
uble in common solvents used for NMR spectroscopy (CDCl3,
CD3CN). The complex undergoes solvolysis in DMSO-d6
solution according to NMR spectroscopic data (1H, 31P, 13C).
The data of the vibrational spectra for the solid complex
and ligand are presented in Table 2. In the IR spectrum of
the complex, ν(P=O) band retains its position as compared
with the band of the free ligand, which indicates that the
phosphoryl group is not involved in coordination. The band
ν(C–H) slightly changes its shape and its maximum is shifted
to 3137 cm−1. Furthermore, the intensity of absorption band
at 1037 cm−1 related to ring deformation decreases and an
absorption at 1065 cm−1 appeared. In the Raman spectrum,
Taking into account the found stoichiometric ratios,
Pd(II) extraction from HCl solutions with compound 1 into
DCE can be described by Eqs. (1, 2):
[
]
2−
[
]
0
PdCl4 (aq) + L(org) ⇄ PdLCl2 (org) + 2Cl(−−aq), K1
(1)
[
]
[
]
0
2−
PdCl4 (aq) + 2L(org) ⇄ PdL2Cl2 (org) + 2Cl(−aq), K2,
(2)
where symbols (org) and (aq) designate the components
of organic and aqueous phases, respectively, K1 and K2 are
equilibrium constants of palladium extraction. The values of
equilibrium constants K1 and K2, calculated from the data of
Fig. 7 are equal to (1.22 0.03)×103 and (1.45 0.03)×106,
respectively.
Scheme 2
Thus, tripodal ligand 1 efciently extracts Pd(II) from
hydrochloric acid solutions into DCE. The extracted com-
plexes have the composition [Pd(L)Cl2] and [Pd(L)2Cl2].
1 3

I. Y. Kudryavtsev et al.
Table 2 Main vibration
Compound
ν(P=O)
IR
ν(C–H)
IR
ν(triazole)
IR
ν(Pd–N)
IR
ν(Pd–Cl)
frequencies for ligand 1 and its
complex 8 (̄ꢀ /cm−1
)
Raman
IR
Raman
1
8
1175sh
1175sh
3130w
3137w
1037m
1065sh
1555, 1358, 1229
1558, 1373, 1236
~ 495br
345br
301, 342
the lines related to vibrations of the triazole ring are shifted
in diferent extent to the high-frequency region, which indi-
cates the participation of the nitrogen atom of the triazole ring
in coordination with Pd(II) cation. The vibrations of coordi-
nated to Pd(II) chloride ions appear in the vibrational spectra
of complex 8 as a split band at 301 and 342 cm−1 in the Raman
spectrum and at~345 cm−1 in the IR spectrum, which is typi-
cal for cis complexes of PdCl2 [44, 45]. The band at 495 cm−1
observed in IR spectrum can be related to a ν(Pd–N) vibra-
tion [44]. It is known that the palladium(II) complexes have a
square planar geometry, typical for complexes with d8 confgu-
ration, the coordination number of Pd(II) is four [24, 30–33,
44]. The body of experimental data allows us to assume that
compound 8 is a neutral cis complex of PdCl2 with ligand 1
molecule coordinated in N,N-bidentate mode.
Hertz (Hz). IR spectra in the region 400-4000 cm−1 were
obtained on a Bruker Tensor 37 FTIR spectrometer. The
solid samples were KBr pellets and mulls in Nujol. Raman
spectra in the range of 100-3500 cm−1 were recorded on a
Jobin–Yvon LabRAM 300 spectrometer, equipped with a
microscope and laser CCD detector. The He–Ne laser emis-
sion line at 632.8 nm was used for excitation at a power not
higher than 2 mW. Mass spectra for solutions of compounds
in methanol were recorded on an AmaZon Bruker Daltonik
GmbH mass spectrometer in Ultra-Scan mode with positive
ionization, detected range was m/z=70–2200. The content
of C, H, and N was determined on a Carlo Erba 1106 instru-
ment. The content of P was determined according to the
published procedures [47]. Melting points were determined
in open capillary tubes on a Stanford Research Systems
MPA120 EZ-melt automated melting point apparatus.
Tris[2-(2′-azidoethoxyphenyl)phosphine oxide (7)
was prepared by a literature procedure [37]. Acetylenes
RC≡CH (R=Ph, 4-MeC6H4, 4-MeOC6H4, 4-t-BuC6H4, n-
Bu, n-C6H13) were purchased from Aldrich and were used
as received. Salts PdCl2 (pure grade), NaCl (pure grade),
PdCl2(NCPh)2 (Aldrich) were used without further purif-
cation. The following reagents were used for the prepara-
tion of solutions in the extraction study: bidistilled water,
1,2-dichloroethane (reagent grade), HCl (high purity grade).
Solutions for spectral and extraction studies were prepared
by volumetric/gravimetric method.
Conclusion
Six new tripodal ligands based on the triphenylphosphine
oxide platform with 1,2,3-triazole fragments in side arms
and diferent alkyl and aryl substituents attached to the tria-
zole rings were synthesized by click reaction in good yields.
The coordination and extraction properties of the new type
of tripodal ligands were studied by the example of ligand 1.
Compound 1 was found to recover efciently (up to 99%)
Pd(II) from hydrochloric acid solutions into 1,2-dichloro-
ethane. The extracted complexes were revealed to have a
composition [Pd(1)Cl2] and [Pd(1)2Cl2]. The model 1:1
complex of ligand 1 with PdCl2 was isolated. The body of
experimental data (IR and Raman spectroscopy, elemental
analysis) allows us to assume that compound 8 is a neutral
cis complex of PdCl2 with ligand 1 coordinated in N,N-
bidentate mode.
X‑ray crystallography
Intensities of the refections for compound 1 were collected
on a Bruker Apex DUO CCD difractometer using CuKα
radiation (λ=1.54178 Å; monochromatted with multilayered
optics) at 120.0(2) K. The structure was solved by ShelXT
method [48] and refned by full-matrix least squares against
F2. Non-hydrogen atoms were refned anisotropically. Posi-
tions of hydrogen atoms were calculated and all hydrogen
atoms were included in the refnement by a riding model
with Uiso(H) = 1.2 Ueq(X). Single crystal contains highly
disordered solvent molecules which have been treated as a
difuse contribution to the overall scattering without the spe-
cifc atom positions by SQUEEZE/PLATON [49]. All calcu-
lations were made using the SHELXL2014 [50] and OLEX2
[51] program packages. Crystal parameters and refnement
details are listed in Table 3. CCDC 2018462 contains the
supplementary crystallographic data for compound 1. These
Experimental
Organic solvents used in the work were purifed by stand-
ard procedures [46]. CDCl3 (99.8% D, Sigma-Aldrich) was
used as received. 1H, 13C{1H}, and 31P{1H} NMR spectra in
CDCl3 were recorded on a Bruker Avance 400 spectrometer
operating at 400.13, 100.61, and 161.98 MHz, respectively.
Chemical shifts (ppm) refer to the residual protic solvent
1
peaks (for H and 13C) and 85% H3PO4 (for 31P{1H}) as
external standards and coupling constants are expressed in
1 3

New tripodal ligand on the triphenylphosphine oxide platform with 1,2,3-triazole side arms:…
Table 3 Crystal parameters and refnement details for compound 1
1 [solvent]
Scheme 3
Formula
Formula weight
Space group
C48H42N9O4P
839.87
P 21/n
a/Å
b/Å
c/Å
11.84(5)
31.95(8)
12.20(4)
98.9(3)
4560(27)
4
β/°
2880vw, 1610vs, 1555m, 1470vw, 1442vw, 1358m, 1229w,
1176w, 1074vw, 1042m, 1000s, 971s, 910vw, 799vw,
770vw, 667m, 610vw cm−1; 1H NMR (400.13 MHz, CDCl3):
δ = 4.12 and 4.24 (12H, both s, H1′, H2′), 6.67 (3H, dd,
3JHH =8.4 Hz, 4JHH =5.2 Hz, H3), 6.88 (3H, t, 3JHH =7.6 Hz,
H5), 7.20–7.45 (15H, m, H4, H6, H3′″, H4′″, H5′″), 7.67 (6H,
d, 3JHH =6.0 Hz, H2′″, H6′″), 8.12 (3H, s, H5″) ppm; 13C NMR
(100.61 MHz, CDCl3): δ=49.12 (C2′), 66.74 (C1′), 111.93
V (Å3)
Z
µ/mm−1
0.965
1.223
dcalc/g cm−3
F(000)
1760
No. of measured refs.
No. of independent refs. (Rint)
No. of observed rfs. [I>2σ(I)]
No. of parameters
Goodness-of-ft
R1 [I>2σ(I)]
29,128
7961 (0.104)
6091
559
1.07
0.085
0.213
0.81, −0.70
3
1
(d, JPC = 6.0 Hz, C3), 120.74 (d, JPC = 109.7 Hz, C1),
121.61 (d, 3JPC =13.1 Hz, C5), 122. 08 (C5″), 125.73 (C2′″,
C6′″), 127.92 (C4′″), 128.63 (C3′″, C5′″), 130.65 (C1′″), 133.91
(d, 2JPC =8.0 Hz, C6), 134.04 (C4), 147.51 (C4″), 159.59 (C2)
ppm; 31P{1H} NMR (161.98 MHz, CDCl3): δ=25.6 ppm;
MS: m/z=840 ([M]+).
wR2 [all data]
Δρmax, Δρmin/e Å−3
Tris[2‑[2′‑(4″‑(4′″‑methylphenyl)‑1″,2″,3″‑triazol‑1″‑yl)‑
ethoxy]phenyl]phosphine oxide (2,C51H48N9O4P) White
powder; yield 77%; T. decomp.: > 135 °C; IR (KBr disk):
̄ꢀ =3369br, 3130w, 3128w, 3077w, 2922w, 2879w, 1590s,
1576m, 1560vw, 1500m, 1479s, 1461m, 1441vs, 1389w,
1366w, 1284m, 1248m, 1230s, 1176m, 1162m, 1139m,
1086m, 1048m, 1033m, 972w, 905w, 824m, 798m, 759s,
704w, 667m, 521m cm−1; 1H NMR (400.13 MHz, CDCl3):
δ=2.34 (9H, s, CH3), 4.12 and 4.23 (12H, both s, H1′, H2′),
data can be obtained free of charge via http://www.ccdc.cam.
ac.uk/structures/, or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
General procedure for synthesis of tris[2‑[2′‑(4″‑R‑
1″,2″,3″‑triazol‑1″‑yl)ethoxy]phenyl]phosphine ox‑
ides 1‑6
3
6.69 (3H, br s, H3), 6.88 (3H, t, JHH = 7.4 Hz, H5), 7.10
A mixture of 0.28 mmol of tris[2-(2′-azidoethoxy)phenyl]
phosphine oxide 7, 1.68 mmol of the corresponding substi-
tuted acetylene, 0.028 mmol of CuBr, and 3 cm3 of CH2Cl2,
was heated under refux for 5 h. The product was isolated by
chromatography on SiO2 or Al2O3 using chloroform–metha-
nol (20:1) mixture as an eluent. The eluate was evaporated to
dryness and the solid residue was triturated with warm ether
to give tris[2-[2′-(4″-R-1″,2″,3″-triazol-1″-yl)ethoxy]phenyl]
phosphine oxides 1–6 in 70–91% yield as powders. Number-
ing scheme for compounds 1–6 is given in Scheme 3.
(6H, d, 3JHH =7.6 Hz, H2′″, H6′″), 7.27–7.44 (6H, m, H4, H6),
7.55 (6H, d, 3JHH =7.6 Hz, H3′″, H5′″), 8.03 (3H, s, H5″) ppm;
13C NMR (100.61 MHz, CDCl3): δ = 21.30 (CH3), 49.16
(C2′), 66.90 (C1′), 112.08 (d, 3JPC =4.3 Hz, C3), 120.79 (d,
1JPC =159 Hz, C1), 121.56, 121.69 (C5, C5″), 125.66 (C2′″,
C6′″), 127.82 (C4′″), 129.30 (C3′″, C5′″), 133.92, 134.05 (C4,
C6), 137.72 (C1′″), 147.66 (C4″), 159.65 (C2) ppm; 31P{1H}
NMR (161.98 MHz, CDCl3): δ=25.3 ppm; MS: m/z=882
([M]+).
Tris[2‑[2′‑(4″‑(4′″‑methoxyphenyl)‑1″,2″,3″‑triazol‑1″‑yl)‑
ethoxy]phenyl]phosphine oxide (3, C51H48N9O7P) White
powder; yield 70%; T. decomp.: > 130 °C; IR (KBr disk):
̄ꢀ =3393br, 3132w, 3080w, 3068w, 2997w, 2933w, 2835w,
1618m, 1590m, 1577m, 1560m, 1500s, 1478m, 1465m,
1441s, 1368w, 1303w, 1284m, 1248vs, 1175m, 1165sh,
1139m, 1108w, 1085m, 1030m, 972w, 909w, 837m, 797m,
Tris[2‑[2′‑(4″‑phenyl‑1″,2″,3″‑triazol‑1″‑yl)ethoxy]phenyl]‑
phosphine oxide (1, C48H42N9O4P) White powder; yield 70%;
T. decomp.:>115 °C; IR (KBr disk): ̄ꢀ =3338br, 3130w,sh,
3080sh, 3066m, 3029sh, 2997sh, 2951sh, 2880vw, 2851vw,
1589s, 1575m, 1563vw, 1477m, 1441vs, 1390vw, 1368vw,
1284s, 1232s, 1175m,sh, 1165m, 1139m, 1085m, 1049sh,
1037m, 970w, 909vw, 849vw, 801w, 761vs, 696s, 610vw,
557m, 520w cm−1; Raman: ̄ꢀ =~3140vw, 3064m, 2952vw,
1
757m, 697w, 662vw, 599w, 557m, 534m cm−1; H NMR
(400.13 MHz, CDCl3): δ = 3.80 (9H, s, CH3), 4.09 and
1 3

I. Y. Kudryavtsev et al.
3
4.20 (12H, both s, H1′, H2′), 6.68 (3H, dd, JHH = 8.4 Hz,
Tris[2‑[2′‑(4″‑hexyl‑1″,2″,3″‑triazol‑1″‑yl)ethoxy]phenyl]‑
phosphine oxide (6, C48H66N9O4P) White powder; yield
75%; m.p.: 114–116 °C; IR (KBr disk): ̄ꢀ =3419br, 3123w,
3068m, 2928vs, 2857s, 1715vw, 1590vs, 1576s, 1551w,
1479s, 1442vs, 1395w, 1368m, 1284vs, 1241vs, 1176m,
1166m, 1140m, 1086m, 1045s, 910m, 846w, 799m,
4JHH = 4.8 Hz, H3), 6.81 (6H, d, 3JHH = 8.4 Hz, H3′″, H5′″),
6.88 (3H, t, 3JHH =7.4 Hz, H5), 7.29–7.41 (6H, m, H4, H6),
7.58 (6H, d, 3JHH =8.4 Hz, H2′″, H6′″), 8.01 (3H, s, H5″) ppm;
13C NMR (100.61 MHz, CDCl3): δ = 49.17 (C2′), 55.38
(CH3), 66.82 (C1′), 111.97 (d, JPC = 6.0 Hz, C3), 114.04
3
(C3′″, C5′″), 120.65 (d, JPC = 109.7 Hz, C1), 121.34 (C5″),
758s, 705m, 666cл, 608w, 557s, 522m cm−1; H NMR
1
1
121.66 (d, 3JPC =12.1 Hz, C5), 123.25 (C1′″), 127.07 (C2′″,
(400.13 MHz, CDCl3): δ=0.85 (9H, t, 3JHH =6.4 Hz, CH3),
1.25 (18H, br s, CH2), 1.52 (6H, br s, CH2), 2.49 (6H, t,
3JHH = 7.4 Hz, CH2), 4.22 (12H, br s, H1′, H2′), 6.90 (3H,
br s, H3), 7.00 (3H, t, 3JHH =6.6 Hz, H5), 7.33 (3H, s, H5″),
7.41–7.58 (6H, m, H4, H6) ppm; 13C NMR (100.61 MHz,
CDCl3): δ=14.08 (CH3), 22.57, 25.63, 29.01, 29.46, 31.57
(CH2), 49.00 (C2′), 67.54 (C1′), 112.57 (d, 3JPC =6.0 Hz, C3),
121.40 (d, 1JPC =109.7 Hz, C1), 121.71 (d, 3JPC =13.1 Hz,
C5), 122.28 (C5″), 133.98 (C4), 134.30 (d, 2JPC =9.1 Hz, C6),
148.27 (C4″), 159.99 (C2) ppm; 31P{1H} NMR (161.98 MHz,
CDCl3): 24.5 ppm; MS: m/z=864 ([M]+).
C6′″), 133.96 (d, JPC = 9.1 Hz, C6), 134.08 (C4), 147.36
2
(C4″), 159.44 (C4′″), 159.60 (C2) ppm; 31P{1H} NMR
(161.98 MHz, CDCl3): δ=25.2 ppm; MS: m/z=930 ([M]+).
Tris[2‑[2′‑(4″‑(4′″‑tert‑butylphenyl)‑1″,2″,3″‑triazol‑1″‑yl)‑
ethoxy]phenyl]phosphine oxide (4,C60H66N9O4P) White
powder; yield 91%; m.p.: 195–196 °C (CH2Cl2–ether); IR
(KBr disk): ̄ꢀ =3400br, 3132w sh, 3090w, 3074w, 2961vs,
2920sh, 2868m, 1590s, 1575m, 1560w, 1496m, 1478s,
1462m, 1442vs, 1392w, 1366m, 1283s, 1240s, 1179m,
1165m, 1140m, 1112w, 1084m, 1050m, 1035m, 973w,
911vw, 841m, 799m 760vs, 702w, 557s, 522w cm−1; H
Synthesis of palladium complex of ligand 1 [Pd(1)Cl2]·3H2O
(8) A solution of 0.0180 g [PdCl2(NCPh)2] (0.0476) mmol)
in 1.5 cm3 of acetonitrile was slowly added with stirring to
a solution of 0.0400 g of ligand 1 (0.0476 mmol) in 3 cm3
of acetonitrile. Upon addition of the salt, the reaction mix-
ture immediately changed from a transparent solution to a
cloudy mixture, which yielded a pale yellow precipitate.
The precipitate was separated by decantation after 3 days.
The powder was washed with acetonitrile and anhydrous
ether and dried in vacuo (~1 Torr) at 62 °C to give 0.030 g
(59%). T. decomp. > 240 °C; IR (KBr disk): ̄ꢀ = 3350br,
3137w sh, 3065w, 2926w, 2101w, 1590s, 1577 m, 1560m,
1474s, 1442vs, 1375w, 1282s, 1235vs, 1175m, 1168m,
1140m, 1117sh, 1087m, ~ 1060sh, 1047m, 1005w, 912w,
799w, 763vs, 697s, 558m, 521w cm−1; Raman: ̄ꢀ =3145vw,
3067w, 2960vw, 1612vs, 1593m, 1558m, 1443vw, 1373m,
1289vw,1236vw, 1164w, 1062w, 1045m, 1001s, 974m,
916vw, 849vw, 799vw, 768vw, 727vw, 670w, 620m, 407vw,
342m, 301s cm−1.
1
NMR (400.13mHz, CDCl3): δ = 1.31 (27H, s, CH3), 4.08
and 4.19 (12H, both s, H1′, H2′), 6.64 (3H, dd, 3JHH =7.8 Hz,
4JHP =5.0 Hz, H3), 6.87 (3H, t, 3JHH =7.2 Hz, H5), 7.30 (6H,
d, 3JHH =8.0 Hz, H3′″, H5′″, signal of H4 is overlapped with
3
the doublet of H3′″ and H5′″), 7.37 (3H, dd, JHH = 6.8 Hz,
3JHP =14.4 Hz, H6), 7.59 (6H, d,3JHH =8.0 Hz, H2′″, H6′″),
8.06 (3H, H5″) ppm; 13C NMR (100.61mHz, CDCl3):
δ = 31.34 (CH3); 34.63 (Ct−Bu), 49.06 (C2′), 66.71 (C1′),
111.93 (d, JPC = 6.1 Hz, C3), 121.64 (d, JPC = 12.3 Hz,
C5), 121.84 (C5″), 125.53 (C2′″, C3′″, C5′″, C6′″), 127.84 (C4′″),
133.9 (C4), 134.0 (d, 2JPC =1.8 Hz, C6), 147.61 (C4″), 150.99
(C1′″), 159.61 (C2) ppm; 31P{1H} NMR (161.98 MHz,
CDCl3): δ=24.9 ppm; MS: m/z=1009 ([M]+).
3
3
Tris[2‑[2′‑(4″‑butyl‑1″,2″,3″‑triazol‑1″‑yl)ethoxy]phenyl]‑
phosphine oxide (5, C42H54N9O4P) White powder; yield
70%; m.p.: 136-138 °C; IR (KBr disk): ̄ꢀ =3404br, 3120w,
3069m, 2957s, 2932s, 2872m, 2219w, 1686m, 1590vs,
1576s, 1551w, 1530w, 1479s, 1442vs, 1372m, 1284s, 1241s,
1176m, 1167m, 1141m, 1086m, 1045s, 911m, 847w, 799m,
759s, 732s, 705m, 644w, 608w, 557s, 521m cm−1; 1H NMR
(400.13 MHz, CDCl3): δ=0.86 (9H, t, CH3, 3JHH =7.2 Hz),
Extraction of palladium(II)
1,2-Dichloroethane of reagent grade was used without addi-
tional purifcation as the organic solvent. The initial aque-
ous palladium(II) solutions were prepared by dissolving
PdCl2 in water, followed by the addition of HCl or NaCl.
The initial concentrations of Pd(II) ions were 2× 10−5 M.
The phases were contacted at room temperature by agitation
with a stirrer at 60 rpm for 1 h, which is sufcient to estab-
lish constant values of distribution ratios (DPd) at volume
ratio of organic and aqueous phases of 1:1. The concentra-
tion of palladium(II) in the initial and equilibrated aqueous
solutions was determined by mass spectrometry with the
inductively coupled plasma ionization of samples (ICP-MS),
3
1.28 (6H, sext, CH2, JHH = 7.3 Hz, CH2), 1.50 (6H, quin
3
3
CH2, JHH = 7.5 Hz), 2.49 (6H, t, CH2, JHH = 7.8 Hz),
3
4.21 (12H, br s, H1′, H2′), 6.89 (3H, dd, JHH = 8.4 Hz,
4JPH = 5.2 Hz, H3), 6.99 (3H, t, JHH = 7.6 Hz, H5), 7.33
3
(3H, s, H5″); 7.41–7.57 (6H, m, H4, H6) ppm; 13C NMR
(100.61 MHz, CDCl3): δ=13.81 (CH3), 22.34, 25.29, 31.53
(CH2), 48.98 (C2′), 67.55 (C1′), 112.56 (d, 3JPC =7.0 Hz, C3),
121.44 (d, 1JPC =110.7 Hz, C1), 121.70 (d, 3JPC =13.1 Hz,
C5), 122.28 (C5″), 133.96 (C4), 134.30 (d, 2JPC =8.0 Hz, C6),
148.26 (C4″), 159.99 (C2) ppm; 31P{1H} NMR (161.98 MHz,
CDCl3): δ=24.4 ppm; MS: m/z=780 ([M]+).
1 3

New tripodal ligand on the triphenylphosphine oxide platform with 1,2,3-triazole side arms:…
22. Turanov AN, Matveeva AG, Kudryavtsev IY, Pasechnik MP, Mat-
using a Thermo Scientifc X-7 mass spectrometer. The con-
tent of Pd(II) in organic phase was determined as the difer-
ence in Pd(II) concentrations in aqueous phase before and
after extraction. The distribution ratios for palladium were
calculated as ratios of the equilibrium concentration in the
organic and aqueous phases (DPd =[Pdorg]/[Pdaq]). The error
of the determined DPd values did not exceed 5%. The HCl
concentration in equilibrium aqueous phase was determined
by potentiometric titration with NaOH solution.
veev SV, Godovikova MI, Baulina TV, Karandashev VK, Brel VK
(2019) Polyhedron 161C:276
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Acknowledgements The work was fnancially supported by the Rus-
sian Science Foundation (project no. 20–13–00329). Spectral stud-
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