A new amido-phosphane as ligand for copper and silver complexes. Synthesis, characterization and catalytic application for azide-alkyne cycloaddition in glycerol

Article abstract of DOI:10.1039/d1dt00992c

The new sterically hindered amido-phosphane 1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-3,7-diylbis(phenylmethanone), DBPTA (1), has been obtained via an open-cage double N-acylation of 1,3,5-triaza-7-phosphadamantane (PTA) using benzoic anhydride. DBPTA i

Full text of DOI:10.1039/d1dt00992c

Showcasing research from Professor Armando Pombeiro's
laboratory at Centro de Química Estrutural, Instituto
Superior Técnico, University of Lisbon, Lisbon, Portugal.
As featured in:
Volume 50
Number 18
14 May 2021
Pages 5991-6358
Dalton
A new amido-phosphane as ligand for copper and silver
complexes. Synthesis, characterization and catalytic
application for azide–alkyne cycloaddition in glycerol
Transactions
An international journal of inorganic chemistry
rsc.li/dalton
A new amido-phosphane has been synthesised and its
coordination properties have been assessed for copper
and silver. The copper complexes act as catalysts for
1,3-dipolar azide–alkyne cycloaddition in glycerol according
to “Click” rules, providing a significant contribution to “Green
Chemistry”.
ISSN 1477-9226
PAPER
Ari Lehtonen et al.
Vanadium aminophenolates in catechol oxidation:
conformity with Finke's common catalyst hypothesis
Anniversary
Volume
See Abdallah G. Mahmoud et al.,
Dalton Trans., 2021, 50, 6109.
rsc.li/dalton
Registered charity number: 207890

Dalton
Transactions
View Article Online
View Journal | View Issue
PAPER
A new amido-phosphane as ligand for copper and
silver complexes. Synthesis, characterization
and catalytic application for azide–alkyne
cycloaddition in glycerol†
Cite this: Dalton Trans., 2021, 50,
6109
Abdallah G. Mahmoud,
Armando J. L. Pombeiro
*
a,b M. Fátima C. Guedes da Silva b and
b,c
The new sterically hindered amido-phosphane 1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-3,7-diylbis
(phenylmethanone), DBPTA (1), has been obtained via an open-cage double N-acylation of 1,3,5-triaza-
7-phosphadamantane (PTA) using benzoic anhydride. DBPTA is the only acyl derivative of PTA that con-
tains an aromatic appendage. Due to the bulky nature of the benzoyl C(O)Ph groups, they exhibit mutual
anti configuration as confirmed by solution NMR and single crystal X-ray diffraction. Compound 1 is
readily soluble in common polar organic and green solvents, making it a very versatile ligand that could be
used in a variety of reaction systems. To assess the coordination characteristics of the new phosphane,
seven copper complexes of formulas [Cu(DBPTA)4]BF4 (2), [CuX(DBPTA)3] {X = Br (3) and I (4)}, [Cu(μ-X)
(DBPTA)2]2 {X = Br (5) and I (6)}, [Cu(bpy)(DBPTA)2]Y {Y = BF4 (7) and BPh4 (8)} {bpy = 2,2’-bipyridine}, and
three silver complexes with formulas [Ag(DBPTA)4]NO3 (9), [Ag(Tpm*)(DBPTA)]NO3 (10) and [Ag(Tpms)
(DBPTA)] (11) {Tpm* = tris(3,5-dimethyl-1-pyrazolyl)methane, Tpms = tris(pyrazol-1-yl)methanesulfonate}
have been synthesised. Compounds 1–11 were characterized by elemental analyses and electrospray
ionization mass spectrometry (ESI-MS), as well as by FT-IR and NMR (1H, 13C, 31P, COSY and HSQC) spec-
troscopic techniques. The catalytic activity of the complexes has been investigated for 1,3-dipolar azide–
alkyne cycloaddition reaction using glycerol as a reaction medium to afford 1,4-disubstituted-1,2,3-tri-
azoles. Complex 7 was found to be the most efficient catalyst, affording triazoles in yields up to 97% after
18 h under standard bench experimental conditions (at 23 °C, aerobic conditions and in the absence of
any additional bases) and up to 98% after 15 minutes under microwave irradiation (125 °C, 30 W). The cat-
alysis proceeds with a broad substrate scope according to “Click” rules providing a significant contribution
to “Green Chemistry”.
Received 25th March 2021,
Accepted 13th April 2021
DOI: 10.1039/d1dt00992c
rsc.li/dalton
DAPTA was obtained through an open cage acylation of
1,3,5-triaza-7-phosphadamantane (PTA) with acetic anhydride.1,3
1. Introduction
The synthesis of the hydrosoluble, air-stable aliphatic phos- Using a similar synthetic protocol other N-acylated derivatives
phane 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane of PTA were obtained by reacting PTA with the respective an-
(DAPTA) was reported of the first time by Siele in 1977 1 but hydride (Scheme 1): 3,7-diformyl-1,3,7-triaza-5-phosphabicyclo-
only recently it has received much attention due to its high
water solubility.2
aDepartment of Chemistry, Faculty of Science, Helwan University, Ain Helwan,
11795 Cairo, Egypt
bCentro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa,
Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
E-mail: abdallah.mahmoud@tecnico.ulisboa.pt
cPeoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya
Street, Moscow 117198, Russian Federation
†Electronic supplementary information (ESI) available. CCDC 2067383. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
d1dt00992c
Scheme 1 Synthesis of N-acylated derivatives of PTA using anhydrides.
Dalton Trans., 2021, 50, 6109–6125 | 6109
This journal is © The Royal Society of Chemistry 2021

View Article Online
Paper
Dalton Transactions
[3.3.1]nonane (DFPTA)4 and 3,7-bis(dichloroacetyl)-1,3,7-triaza- 1,2,3-triazoles, reported for the first time at the beginning of
5-phosphabicyclo[3.3.1]nonane (DCPTA).5 In the last two this century,9,10 fulfils the criteria of Click Chemistry estab-
decades, the di-N-acylated PTA derivatives that belong to the lished by the Nobel laureate Karl Sharpless and coworkers.11
growing family of open-cage PTA analogues6,7 have been used Cu-AAC is the most prolific and successful example of Click
as ligands in a variety of coordination compounds for catalytic, reactions in view of its massive variety of applications in bio-
medicinal and photoluminescence applications.2
logical chemistry and material science.12–14 In general, there
The N-acylation of PTA using different anhydrides should are two routes to perform the Cu-AAC reaction as depicted in
produce new derivatives with different acyl groups and various Scheme 2, (i) the direct treatment of an alkyne with an organic
electronic and steric features. In this context, and pursuing azide; and (ii) the reaction of an alkyne with an in situ gener-
our interest in the synthesis of new DAPTA derivatives,8 herein ated organo-azide obtained from the corresponding organic
we describe the synthesis of the new sterically hindered phos- halide and sodium azide. The latter three-component reaction
phane 1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-3,7-diylbis (alkyne, organic halide and NaN3)15 avoids the difficulties
(phenylmethanone) {DBPTA (1); Fig. 1} where PTA is functio- associated with isolating and handling organic azides, in par-
nalized with two benzoyl groups.
ticular those of low molecular weight.16,17 Our group has
A set of novel well-defined homoleptic and mixed-ligand recently reported efficient catalytic systems based on DAPTA
Cu(I) and Ag(I) complexes bearing DBPTA were obtained to investi- and derivatives for the CuAAC reaction in aqueous
gate the coordination behaviour of the new phosphane. In medium.8,18,19
order to prepare mixed-ligand metal complexes involving poly-
Several catalytic protocols based on silver complexes have
dentate ligands, 2,2′-bipyridine (bpy) and C-scorpionates, viz. also been studied for the 1,3-dipolar azide–alkyne cyclo-
tris(3,5-dimethyl-1-pyrazolyl)methane HC(3,5-Me2pz)3 (Tpm*) addition to afford the 1,4-regioisomers of 1,2,3-triazoles,20 but
and tris(pyrazol-1-yl)methanesulfonate−O3SC(pz)3 (Tpms), high catalyst loadings and the presence of additives (e.g.
have been used (Fig. 2). The obtained compounds have been caprylic acid) were required for an efficient catalytic
fully characterized by elemental analysis and ESI-Ms spec- system.21–23
1
trometry, FT-IR and NMR spectroscopies, the latter using H,
Glycerol is a biomass-derived solvent, which can be
13C{1H} and 31P{1H} NMR, as well as 2D-NMR techniques obtained from the bio-diesel industry or lignocellulose
(COSY and HSQC). The catalytic activity of the complexes was conversions.24–26 It has attracted significant attention as a
investigated for the 1,3-dipolar alkyne–azide cycloaddition green and sustainable solvent candidate to replace noxious
reaction in glycerol.
organic solvents for organic synthetic processes due to its
The copper catalyzed azide–alkyne cycloaddition (Cu-AAC) unique set of physical and chemical properties including high
reaction to selectively and efficiently provide 1,4-disubstituted- polarity, low toxicity, non-flammability, high boiling point and
high tendency to dissolve inorganic and organic
compounds.27,28 In 2014, glycerol has been utilized for the
first time as a reaction medium for CuAAC using a catalytic
system based on CuI salt.29 Since then, only a few studies have
been performed for the CuAAC reaction in glycerol using
either simple copper salts (e.g. CuI) or Cu(I)-based-nano-
particles as catalysts.30
Hence, in view of the already explored CuAAC studies in
water,14 the virtually unexplored use of glycerol as a solvent in
Fig. 1 Structure of DBPTA (1), 1,3,7-triaza-5-phosphabicyclo[3.3.1]
nonane-3,7-diylbis(phenylmethanone).
this reaction, its availability and worldwide recognition as an
Fig. 2 Auxiliary ligands employed in this work: (a) 2,2’-bipyridine, bpy; (b) tris(3,5-dimethyl-1-pyrazolyl)methane HC(3,5-Me2pz)3, Tpm*; (c) tris
(pyrazol-1-yl)methanesulfonate−O3SC(pz)3, Tpms.
6110 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
triazacyclohexane ring and eliminating benzoic acid and
formaldehyde.
Compound 1 was obtained as air stable colourless crystals.
It was also stable in solution for at least 15 days in DMSO-d6 or
CDCl3 for 1H and 31P NMR observation. DBPTA is water in-
soluble due to its high carbon content and the presence of two
phenyl hydrophobic groups. However, it shows a remarkable
solubility in halogenated hydrocarbons (chloroform and
methylene chloride), alcohols (methanol, ethanol and gly-
cerol), acetone, acetonitrile, pyridine, dimethylformamide and
dimethyl sulfoxide. It also exhibits good solubility in dimethyl
carbonate, ethyl acetate, 2-methyltetrahydrofuran, ethyl lactate
and cyrene. Upon addition of water to a DMSO solution of 1 it
remains dissolved even if the H2O/DMSO ratio increased to
10 : 1.
Scheme 2 The two routes to perform CuAAC reaction.
environmentally benign non-toxic solvent,27,28 its multifunc-
tionality and potential promoter role of the reaction, the main
goal of the present study was to try to explore its possible util-
ization as a key reaction medium. In addition, the hydrosolubi-
lity of glycerol would be a further advantage in case water :
glycerol solvent mixtures would be favourable, e.g. to solubilize
all the reagents.
With these precedent aspects in mind and pursuing our
interest on studying DAPTA derivatives and CuAAC reactions
under sustainable conditions,8,18,19,31–33 herein we describe (i)
the synthesis and characterization of a novel sterically hin-
dered derivative of PTA, i.e., the di-N-benzoylated analogue of
DAPTA, 1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-3,7-diylbis
(phenylmethanone) {DBPTA, 1}; (ii) the synthesis under mild
conditions and characterization of a library of new Cu(I) and
Ag(I) complexes bearing the DBPTA ligand viz. [Cu(DBPTA)4]
BF4 (2), [CuX(DBPTA)3] {X = Br (3) and I (4)}, [Cu(μ-X)
(DBPTA)2]2 {X = Br (5) and I (6)}, [Cu(bpy)(DBPTA)2]Y {Y = BF4
(7) and BPh4 (8)}, [Ag(DBPTA)4]NO3 (9), [Ag(Tpm*)(DBPTA)]NO3
(10) and [Ag(Tpms)(DBPTA)] (11); and (iii) the investigation of
the catalytic activity of the metal complexes towards the 1,3-
dipolar azide–alkyne cycloaddition reaction using glycerol as
solvent and under aerobic conditions, fulfilling the Click
criteria.
Elemental analysis and ESI-MS, FT-IR and NMR (1H, 13C
{1H} and 31P{1H}) spectroscopies were employed to confirm
the empirical formulae of 1. In addition, its structure was
authenticated by single-crystal X-ray diffraction (SCXRD)
analysis.
1
The H, 13C{1H} and 31P{1H} NMR spectroscopic data for 1
were obtained in CDCl3 and DMSO-d6, and the assignments
for all 1H and 13C signals were provided based on 2D NMR
(Fig. S2–S13†). The 1H NMR spectra of DBPTA in CDCl3
(Fig. S2†) and DMSO-d6 (Fig. S8†) show eight signals for the
ten methylene cage protons; four resonances correlated to the
PCH2N groups (three signals integrate as one proton and the
fourth as three protons) and four resonances were assigned to
the four protons in the NCH2N groups.
The 31P NMR spectra of 1 in CDCl3 (Fig. S3†) and DMSO-d6
(Fig. S9†) show one sharp signal in each case at −77.86 and
−77.36 ppm, respectively. The presence of only one 31P-reso-
nance suggests that DBPTA shows only one isomeric form in
solution. The presence of two distinct signals for the carbonyl
(CvO) groups in the 13C{1H} NMR spectra in CDCl3 (Fig. S4†)
and DMSO-d6 (Fig. S10†) reveals the non-equivalent nature of
these groups and indicates the anti configuration of the
benzoyl C(O)Ph groups, what was confirmed by SCXRD (see
below). Contrasting with other DAPTA derivatives that exhibit
up to three isomeric forms in solution,2 DBPTA shows only the
anti conformation. This can be attributed to the bulky nature
of the benzoyl groups that prevents the rotation around the
N–Ccarbonyl bond. As an attempt to overtake such rotational
barrier, the 31P NMR experiment was performed at 110 °C in
DMSO-d6. However, the widening of the observed peak pre-
vented any clear conclusion.
2. Results and discussion
2.1. Synthesis and characterization of DBPTA (1)
DBPTA (1) is synthesised by direct acylation of PTA with
benzoic anhydride in a mixture of water and acetonitrile (1 : 1),
at 5 °C (Scheme 3). The presence of a surfactant, sodium
dodecyl sulfate (SDS), is required to obtain 1 in good yield
(38%) by improving the solubility of the reactants and the
homogeneity of the reaction medium. The mechanism of
DBPTA formation is expected to follow the general mechanism
of PTA acylation,2 which involves cleaving the C–N bond of the
Scheme 3 Synthesis of DBPTA (1) by acylation of PTA with benzoic anhydride.
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6111

View Article Online
Paper
Dalton Transactions
to be of potential interest to classify this type of phosphanes
and their metal complexes in terms of potential impact in
their biological and/or catalytic properties.2 Compound 1 is
involved in H-bond interactions with the crystallization water
molecule which donates to the O-atom of one phosphane and
to the N-atom of another (Fig. S1†), thus generating a 1D chain
that expands along the crystallographic a axis.
2.2. Synthesis and spectral characterization of the complexes
DBPTA can behave as a multifunctional ligand with diverse
bonding possibilities in view of its six potential coordination
sites: one bridgehead phosphorus, two O-benzoyl and three N
atoms. Therefore, a series of copper and silver complexes
incorporating DBPTA were synthesised and characterized by
elemental analysis and ESI-MS, as well as by FT-IR and NMR
(1H, 13C{1H} and 31P{1H}) spectroscopies.
The homoleptic copper(I) complex, [Cu(DBPTA)4]BF4 (2),
was obtained from the labile precursor [Cu(MeCN)4]BF4 by
MeCN/DBPTA ligand exchange in air and under mild con-
ditions (Scheme 4). The reaction of CuX (X = Br or I) with the
phosphane in air and at 23 °C yields the Cu(I) complexes [CuX
(DBPTA)3] (3 and 4) when a 1 : 4 metal-to-DBPTA stoichiometric
Fig. 3 ORTEP diagram of 1 (ellipsoids drawn at 20% probability level;
water molecule is omitted) with atom numbering scheme. Selected
bond distances (Å) and angles (°): P1–C1 1.812(7), P1–C2 1.802(6), P1–
C3 1.793(7), N1–C1 1.469(7), N1–C4 1.478(6), N1–C7 1.356(7), N2–C2
1.471(5), N2–C5 1.476(5), N2–C14 1.329(5), N3–C3 1.465(7), N3–C4
1.499(7), N3–C5 1.511(6), O1–C7 1.230(5), O2–C14 1.235(5), C1–P1–C2
103.4(3), C1–P1–C3 97.7(3), C2–P1–C3 98.3(3), C1–N1–C4 116.3(5),
C1–N1–C7 119.7(4), C1–N1–C7 119.7(4), C2–N2–C5 115.6(3), C2–N2–
C14 123.9(3), C5–N2–C14 120.3(3), C3–N3–C4 111.7(4), C3–N3–C5
110.8(4), C4–N3–C5 110.7(4).
The asymmetric unit of 1, obtained by single crystal X-ray ratio was used (Scheme 5, route I). Increasing the amount of
diffraction analysis at 23 °C, contains one molecule of the DBPTA in the reaction medium under the same conditions
compound (Fig. 3) and a water solvent molecule. Bond dis- does not affect the final product. However, a decrease in that
tances and angles (legend of Fig. 3) are in the range of those ratio to 1 : 2 led to the isolation of compounds [Cu(μ-X)
measured in other opened-cage PTA derivatives.3–5 In each (DBPTA)2]2 (5 and 6) (Scheme 5, route II).
branch the carbonyl groups are oriented differently relatively
The colourless complexes 2–6 are air and moisture stable.
to the attached phenyl moiety; while the least-square plane Analogously to the DBPTA ligand, they are not soluble in water
made with N1–C7–O1 makes an angle of 49.37° with the and organic non-polar solvents. Complexes 2–4 are highly
attached phenyl, that of N2–C14–O2 is nearly orthogonal with soluble in the common organic polar solvents (alcohols,
the C15 > C20 aromatic ring (89.15°). The least-square planes chlorinated solvents, MeCN, acetone, DMF and DMSO).
of the phenyl groups, in turn, make an angle of 87.47°. The Complex 5 is soluble in CHCl3, DMF and DMSO. Complex 6 is
CCvO⋯CCvO distance of 3.471(6) Å is one of the greatest soluble only in DMF and DMSO.
measured for the, yet in limited number, open cage phos-
The NMR spectroscopic data were obtained in DMSO-d6 for
phanes being exceeded only by the 3,7-bis(dichloroacetyl)- complexes 2–6, and also in CDCl3 for complexes 3–5 (Fig. S14–
1
1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DCPTA) for which S57†). In all cases, H NMR analysis show a set of multiplets
that dimension is of 3.789(5) Å.2 This parameter was proposed arising from the aliphatic methylene protons. When compared
Scheme 4 Synthesis of the complex [Cu(DBPTA)4]BF4 (2).
6112 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
Scheme 5 Synthesis of Cu(I) complexes [CuBr(DBPTA)3] (3), [CuI(DBPTA)3] (4), [Cu(μ-Br)(DBPTA)2]2 (5) and [Cu(μ-Br)(DBPTA)2]2 (6).
to the free phosphane and in view of the different chemical solutions.34,35 The dimeric nature of complexes 5 and 6 was
shifts and splitting patterns (Fig. 4), the resonances of the confirmed by the presence of [Cu2X2{DBPTA} + H]+ fragments
NCH2P protons (labels a–c) seem to be more affected by (m/z 642, X = Br; m/z 734, X = I).
coordination than those of NCH2N (labels d and e).
In order to synthesize a copper complex bearing both
The 31P{1H} NMR spectra of the compounds show one DBPTA and bpy ligands, [Cu(MeCN)4]BF4 was reacted in aceto-
broad signal in each case, downfield shifted from the corres- nitrile with an equimolar amount of bpy and two equivalents
ponding signal of free DBPTA (Fig. 5). The broadness of the of 1 at room temperature (23 °C) to afford [Cu(bpy)(DBPTA)2]
31P resonances is attributed to a fluxional behaviour in solu- BF4 (7) in good yield (66%) and as a bright green solid
tion involving ligand exchange of DBPTA and DMSO, what is (Scheme 6, route I). The same cationic complex with a bulkier
common for [M(P)n]+ (M = Cu and Ag; P = PTA derivatives) type counter anion was obtained by the treatment of CuBr with 1,
of complexes.18,34–37
bpy and NaBPh4 at room temperature (23 °C) affording
The 13C{1H} NMR data for 2–6 are consistent with the anti [Cu(bpy)(DBPTA)2]BPh4 (8) in 35% yield as a pale yellow solid
orientation of the benzoyl groups of DBPTA ligands by reveal- (Scheme 6, route II).
ing their magnetically inequivalent features as two distinct
Complexes 7 and 8 are both air and moisture stable, and
resonances for the two quaternary CvO carbons. Upon coordi- soluble in common organic polar solvents. Their 1H and 13C
nation to the copper centre, the NCH2P carbon signals are NMR spectra in DMSO-d6 exhibit a set of signals corres-
shifted downfield when compared to those of the free ligand.
ponding to the DBPTA and bpy (Fig. S58, S60, S64 and S66†),
The IR spectra of 2–6 show a set of bands attributable to slightly shifted when compared to the free ligands (Fig. S90†).
the ν(CvO) stretching vibrations at 1618, 1613, 1616, 1614 and The 31P{1H} NMR spectra (Fig. S59 and S65†) exhibited broad
1612 cm−1, respectively. For 3–6, intense Cu–halide stretching singlets at −64.01 (7) and −64.13 ppm (8), downfield shifted
vibration bands at 221, 218, 229 and 224 cm−1, in this order, from that of uncoordinated DBPTA (Fig. S91†).
were detected.
Silver complexes bearing the DBPTA and a C-scorpionate as
No [M]+ molecular ion peaks were observed in the ESI(+)MS ligands have also been obtained under mild conditions
spectra of 2–6; their absence is typical for [Cu(P)4]+ complexes (Scheme 7). The homoleptic silver complex [Ag(DBPTA)4]NO3
and due to dissociation processes occurring in diluted (9) was synthesised by reacting silver nitrate with a four-fold
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6113

View Article Online
Paper
Dalton Transactions
Fig. 4 1H NMR spectra of DBPTA (1) and the copper complexes 2–6 in DMSO-d6.
Fig. 5 31P{1H} NMR spectra of DBPTA (1) and the copper complexes 2–6 in DMSO-d6.
6114 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
Scheme 6 Synthesis of the Cu(I) complexes [Cu(bpy)(DBPTA)2]BF4 (7) and [Cu(bpy)(DBPTA)2]BPh4 (8).
Scheme 7 Synthesis of Ag(I) complexes [Ag(DBPTA)4]NO3 (9), [Ag(Tpm*)(DBPTA)]NO3 (10) and [Ag(Tpms)(DBPTA)]NO3 (11).
molar equivalents of 1 in acetonitrile solution alkalized by routes II and III). Complexes 9–11 precipitated from the con-
aqueous ammonia (Scheme 7, route I). Treatment of silver centrated reaction mixtures as light-, air- and moisture-stable
nitrate in methanol with equimolar amounts of 1 and Tpm* or solids; they are soluble in DMSO, acetone and alcohols, but in-
Li-Tpms (i.e. Ag/DBPTA/scorpionate = 1 : 1 : 1) at room tempera- soluble in water and nonpolar organic solvents.
ture (23 °C), led to the formation of [Ag(Tpm*)(DBPTA)]NO3
The NMR spectroscopic data for 9–11 were obtained in
(10) or [Ag(Tpms)(DBPTA)]NO3 (11), respectively (Scheme 7, DMSO-d6 and (for 10) also in CDCl3 (Fig. S70–S89†). The
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6115

View Article Online
Paper
Dalton Transactions
31P{1H} NMR spectra (Fig. S92†) exhibit a broad signal at δ reacted with an equimolar amount of 1, followed by the
−59.62 (9), −54.64 (10) and −56.17 ppm (11), deshielded with addition of Tpm* or Tpms under similar experimental con-
respect to that of free DBPTA (δ −77.36). The set of signals of ditions to those used to obtain 10 and 11. However, the oxi-
the methylene protons of DBPTA in the DMSO-d6 1H NMR dized Cu(II) complexes [Cu(κ3NNN-Tpm*)][BF4]2 and [Cu{κ3(N,
spectra occur at different chemical shifts (5.5–3.5 ppm) and N′,O)-O3SC(pz)3}2]32,40 were the sole species obtained, which
with different splitting patterns when compared to the free indicates the stronger coordination ability of the scorpionates
1
ligand (Fig. S93†). For complexes 10 and 11, H and 13C-NMR in comparison to DBPTA.
spectra show the equivalence of the three pyrazolyl rings by
2.3. Catalytic activity study for the azide–alkyne
cycloaddition
exhibiting a single resonance for each type of protons or
carbons, which is consistent with the κ3NNN-coordination
mode to the Ag(I) centre. The coordination of the Tpm* ligand
in 10 was confirmed by the downfield shift of the Me- and
H-pyrazolyl resonances when compared to free Tpm*
(Fig. S94†). In 11, the H3- and H4-pyrazolyl protons are more
affected by coordination as revealed by their downfield shift
upon Tpms coordination (Fig. S95†).
Complexes 2–11 were tested as catalysts for the azide–alkyne
cycloaddition reaction by using, as model, the reaction of
phenylacetylene with benzyl azide to obtain 1-benzyl-4-phenyl-
1H-1,2,3-triazole. The screening reactions were performed in
neat glycerol, at room temperature (23 °C) and with a catalyst
loading of 1 mol%. Following the “Click laws”,11 the reactions
were performed in air. Their course was monitored by TLC and
the results are depicted in Table 1, entries 1–7.
The copper complexes 2–8 are active catalysts for the reac-
tion affording 1-benzyl-4-phenyl-1H-1,2,3-triazole as the
unique product in moderate to high yields, with complex [Cu
(bpy)(DBPTA)2]BF4 (7) exhibiting the highest activity (94% yield
in 18 h; Table 1, entry 6). The relatively low activity of com-
plexes 5 and 6 is attributed to their low solubility in glycerol.
Concerning the catalytic activity of the silver complexes
9–11 (Table 1, entries 8–10), while 9 and 11 did not provide
any adduct, a relatively high loading of complex 10 (20 mol%)
was needed to achieve only 12% of the 1,4-triazole after 48 h.
The ν(CvO) stretching vibrations in 9–11 were respectively
detected at 1616, 1618 and 1619 cm−1. In addition, the IR spectra
also confirm the presence of the C-scorpionate ligands in view of
the ν(CvN) stretching bands at 1562 (10) and 1540 cm−1 (11), for
the latter also the bands at 1043 cm−1 (SO) and 653 (CS) cm−1
.
In the ESI(+)MS spectra of the silver complexes, the mole-
cular ion [M]+ peak is detected only for 11 together with higher
mass adducts formed by the addition of Ag(Tpms) fragments,
a typical behaviour in mass spectra of Ag(I) complexes bearing
Tpms ligands.38,39
As an attempt to obtain mixed-ligand Cu(I) complexes
bearing DBPTA and C-scorpionates, [Cu(MeCN)4]BF4 was
Table 1 Catalytic 1,3-dipolar cycloaddition of phenylacetylene and benzyl azide promoted by complexes 2–11 to obtain 1-benzyl-4-phenyl-1H-
1,2,3-triazolea
Entry
Catalyst (mol%)
Solvent
Time (h)
Yieldb (%)
TONc
1
2
3
4
5
6
7
8
2 (1)
3 (1)
4 (1)
5 (1)
6 (1)
7 (1)
8 (1)
9 (20)
10 (20)
11 (20)
7 (1)
7 (1)
7 (1)
7 (1)
7 (1)
7 (1)
7 (1)
7 (5)
7 (1)
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Glycerol
Water
Ethanol
Ethyl acetate
Ethyl lactate
Cyrene
2Me–THF
Water/glycerol (1 : 1)
Glycerol
48
24
24
24
24
18
18
48
48
48
18
18
18
18
18
18
18
2
64
77
81
42
21
94
89
—
12
—
—
78
57
35
47
32
91
95
91
64
77
81
21d
11d
94
89
9
10
11
12
13
14
15
16
17
18
19e
78
57
35
47
32
18
95
64
Glycerol
4
a Reaction conditions: phenylacetylene (0.3 mmol), benzyl azide (0.3 mmol), solvent (2 mL), room temperature (23 °C). b Isolated yield. c Number
of moles of product per mol of catalyst. d Number of moles of product per mole of metal centre. e Reaction performed at 100 °C.
6116 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
The reaction did not proceed in the absence of the metal
catalysts.
The effect of glycerol and of water : glycerol solvent mixtures
in the model CuAAC reaction (phenylacetylene, benzyl
The catalytic activity of the copper complex 7 was studied in bromide and NaN3) catalysed by 7 and under microwave
different solvents including water, ethanol, ethyl acetate, ethyl irradiation, was also evaluated (Table 2).
lactate, cyrene and 2-methyltetrahydrofuran (Table 1, entries
The triazole product was obtained in a relatively low yield of
11–17). The reaction did not proceed using water alone conceiva- 38% using glycerol as the sole solvent (Table 2, entry 1), poss-
bly due to the hydrophobic nature of the reactants and the cata- ibly due to the low solubility of sodium azide in glycerol. In
lyst (Table 1, entry 11). However, a 1 : 1 mixture of water and gly- this case, the presence of water in the reaction medium is
cerol promoted the homogeneity of the reaction medium and necessary to dissolve sodium azide, while the organic co-
the efficiency of the catalytic process, and thus the obtainment solvent is important for solubilization of the other com-
of the 1,4-triazole in 91% yield after 18 h (Table 1, entry 17). ponents and thus, using a 1 : 1 mixture of water and glycerol,
Catalyst 7 displays lower activity in other polar solvents (Table 1, the yield was improved to 68% (Table 2, entry 2). Raising the
entries 12–16) when compared to glycerol (Table 1, entry 6).
catalyst loading in the reaction medium increased the product
Using the higher 5 mol% loading in catalyst 7 accelerates yield (Table 2, entries 2–4), and a nearly quantitative conver-
the reaction and 95% yield was achieved in only 2 h. Upon sion was achieved by using 5 mol% of the catalyst.
raising the temperature to 100 °C, 91% of the product was
obtained after only 4 h (Table 1, compare entries 6 and 19).
Several 1,4-disubstituted-1,2,3-triazoles were successfully
obtained from various alkynes and substituted benzyl bromides
The azide : alkyne cycloaddition reaction performed in the in the presence of sodium azide, under microwave irradiation
presence of 1 mol% of catalyst 7 in glycerol and under micro- and with 7 as catalyst (Scheme 9); yields ranged from 88 to 98%
wave irradiation (30 W) at 125 °C, led to 97% yield of the tri- after 15 min, without any detected by-products.
azole product in only 15 min. The 1H NMR spectrum of the
In the restricted number of CuAAC reactions reported in
final reaction product shows no detectable formation of unde- glycerol, copper(I) iodide or Cu(I)-based-nanoparticles were
sired by-products.
employed as catalysts.30 To the best of our knowledge, our
The scope of the catalytic methodology was also assessed. study constitutes the first example of well-defined copper(I)
Various aromatic terminal alkynes were allowed to react with complexes being used as catalysts for the CuAAC reaction in
benzyl azide in glycerol, in the presence of catalyst 7 (1 mol%) glycerol. Although our yields are comparatively modest when
with stirring either (i) at room temperature (23 °C) for 18 h, or using glycerol alone, the water : glycerol (1 : 1) solvent mixture
(ii) under microwave irradiation at 125 °C for 15 min. The reac- and MW irradiation gave almost quantitative products in a
tions proceeded smoothly to afford the corresponding 1,4-di- short time.
substituted-1,2,3-triazoles, which were isolated with yields in the
In comparison with the previously reported copper(I)-
range of 78–97% (Scheme 8) after simple filtration or extraction.
{DAPTAvNP(vS)(OR)2} catalysts for the CuAAC reaction, cata-
Scheme 8 One-pot synthesis of 1,4-disubstituted-1,2,3-triazoles via azide–alkyne cycloaddition reaction catalysed by the copper complex 7 in
glycerol.
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6117

View Article Online
Paper
Dalton Transactions
Table 2 Three-component catalytic CuAAC reaction of phenylacetylene, benzyl bromide and sodium azide to produce 1-benzyl-4-phenyl-1H-
1,2,3-triazole catalysed by compound 7 a
Entry
Catalyst loading (mol%)
Solvent
Yieldb (%)
TONc
1
2
3
4
1
1
3
5
Glycerol
38
68
91
98
38
68
30
20
Water/glycerol
Water/glycerol
Water/glycerol
a Reaction conditions: phenylacetylene (0.3 mmol), benzyl bromide (0.3 mmol), sodium azide (0.3 mmol), catalyst 7, 1.5 mL of solvent (1 : 1 in
case of solvent mixtures), microwave irradiation (30 W), 15 minutes, 125 °C. b Isolated yield. c Number of moles of product (1-benzyl-4-phenyl-1H-
1,2,3-triazole) per mol of catalyst.
Scheme 9 1,4-Disubstituted-1,2,3-triazoles synthesised by a three-component CuAAC reaction catalysed with complex 7 under microwave
irradiation.
lyst 7 exhibits a higher efficiency to selectively obtain the 1,4- cerol and water, even if the water amount increased to a 4 : 1
disubstituted-1,2,3-triazoles using glycerol (or a mixture of H2O/glycerol ratio, the triazole products obtained can be easily
water and glycerol) and in the absence of any bases or redu- isolated and in high purity at the end of the catalytic reaction
cing agents.41 The hydrosoluble Cu(I) complexes [CuX by simply adding water followed by filtration.
(DAPTA)3] and [Cu(μ-X)(DAPTA)2]2 (X = Br or I) showed a great
A proposed mechanism of the reaction is depicted in
efficiency for the CuAAC reaction giving quantitative yields in Scheme 10, considering several studies that have been per-
aqueous medium under microwave irradiation; however, the formed to establish it.9,33,48–50 The initial π-coordination of the
organic co-solvent (MeCN) was required for the reaction to terminal alkyne to the Cu(I) centre increases the acidity of the
proceed efficiently.18
alkyne terminal proton. The formation of the σ-copper acety-
Unlike other water-insoluble catalysts of Cu(I) complexes lide complex is promoted by glycerol, which is close to the
based on phosphines,42 N-heterocyclic carbenes43–45 or tris coordination sphere due to the formation of hydrogen
(triazolyl) methanols,46,47 our catalyst 7 was inactive in pure bonding between one hydroxyl group and the terminal nitro-
water. However, since 7 remains soluble in a mixture of gly- gen of the azide group.51,52 Such intermolecular contact would
6118 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
Scheme 10 Plausible mechanism of the Cu–AAC reaction in glycerol.
enhance the electrophilicity of the distal nitrogen and promote
The possibility of expanding the family of open-cage acy-
the acetylide–azide coupling. The protonation of the copper(I) lated derivatives of PTA, their range of solubility, metal-coordi-
triazolide produces the favoured regioisomer 1-R2-4R1-1,2,3-tri- nation properties and catalytic applications of the derived
azole and regenerates the active copper species catalyst, complexes is being explored.
thereby completing the catalytic cycle.
4. Experimental
4.1. General procedures
3. Conclusions
In this study, a novel phosphane has been added to the library All synthetic procedures were performed in air without consid-
of PTA derivatives. The open cage acylation of PTA using ering any precautions to exclude oxygen, unless stated other-
benzoyl anhydride led to the formation of 1,3,7-triaza-5- wise. Reagents and solvents were obtained from commercial
phosphabicyclo[3.3.1]nonane-3,7-diylbis(phenylmethanone) sources and used without further purification. 1,3,5-triaza-
{DBPTA, 1}, the first DAPTA derivative with an aromatic appen- 7-phosphadamantane (PTA),53 tris(3,5-dimethyl-1-pyrazolyl)
dage. Compound 1 is insoluble in water and nonpolar organic methane (Tpm*),54 and lithium salt of tris(pyrazol-1-yl)metha-
solvents but highly soluble in common organic and green nesulfonate (Li-Tpms)55 were prepared according to the pub-
polar solvents. Contrasting with other acylated derivatives of lished methods.
PTA only the anti rotameric form was detected both in solution
Elemental analyses (C, H, and N) were carried out by the
and in the solid state, conceivably due to the bulky nature of Microanalytical service of Instituto Superior Técnico.
the benzoyl –C(O)Ph groups that prevent the rotation around
the N–Ccarbonyl bond.
FT-IR spectra (4000–400 cm−1) were obtained in a Cary 630
FTIR spectrometer; wavenumbers are in cm−1; abbreviations:
Among the newly synthesized and fully characterized Cu(I)- s, strong; m, medium; w, weak. Far IR spectra (400–180 cm−1
)
and Ag(I)–DBPTA complexes, that with bipyridine co-ligand, were recorded on a Bruker Vertex 70 spectrophotometer in CsI
[Cu(bpy)(DBPTA)2]BF4 (7), was the most active catalyst for the pellets.
AAC reaction, in glycerol, following the “Click” rules. The
1H, 13C and 31P NMR spectra were obtained using a Bruker
yields in triazoles ranged from 78 to 97% either working at Advance III 300 or 400 MHz UltraShield Magnet spectrometer,
room temperature (23 °C) for 18 h, or under microwave at ambient temperature. Chemical shifts δ are quoted in ppm,
irradiation at 125 °C for 15 min. Slightly better yields (between and coupling constants are given in Hz. Multiplicities were
88 and 98%) were achieved with in situ generated organic abbreviated as follows: singlet (s), doublet (d), multiplet (m),
azides (from substituted organic benzyl bromides and sodium doublet of doublets (dd) and broad singlet (br s). 1H and
azide) reacting with terminal alkynes in the presence of 7 as 13C NMR spectra were internally referenced to residual protio-
catalyst, in a mixture of water and glycerol and under the same solvent resonance and are reported relative to tetramethyl-
experimental conditions.
silane (δ = 0); 31P chemical shifts were referenced with external
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6119

View Article Online
Paper
Dalton Transactions
1
85% H3PO4. Assignments of some H and 13C signals rely on PCH2N), 3.64–3.58 (m, 3H, PCH2N). 31P{1H} NMR (400 MHz,
2D NMR experiments, COSY and HSQC.
DMSO-d6, δ): −77.36. 13C{1H} NMR (400 MHz, DMSO-d6,
Electrospray mass (ESI-MS) spectra were obtained on a δ)/DEPT/HSQC: 169.85 (C–O), 169.39 (C–O), 135.79 (Cquat–Ph),
Varian 500-MS LC Ion Trap Mass Spectrometer equipped with 135.6 (Cquat–Ph), 129.5 (HC–Ph), 129.31 (HC–Ph), 128.41 (HC–
an electrospray ion source. For electrospray ionization, the Ph), 128.11 (HC–Ph), 127.72 (HC–Ph), 127.12 (HC–Ph), 68.3
1
drying gas and flow rate were optimized according to the (NCH2N), 61.79 (NCH2N), 44.96 (d, JPC = 61.2, PCH2N), 43.87
1
1
particular sample with 35 p.s.i. nebulizer pressure. All com- (d, JPC = 105.2, PCH2N), 36.86 (d, JPC = 108.4, PCH2N). DEPT
pounds were observed in the positive mode (capillary voltage = (400 MHz, DMSO-d6, δ): 129.25, 129.06, 128.16, 127.86, 127.47,
80–105 V).
126.87, 68.04, 61.54, 44.71, 43.62, 36.61. ESI(+)MS in MeOH
Synthesis under microwave irradiation was carried out in (m/z assignment, % intensity): 729 ([2{DBPTA} + Na]+, 78), 707
an Anton Paar (Monowave 300) apparatus. The reactions were ([2{DBPTA} + H]+, 75), 386 ([DBPTA + MeOH + H]+, 8), 354
performed in 10 mL cylindrical Pyrex tubes, sealed with a ([DBPTA + H]+, 100).
Teflon crimp top.
4.3. Synthesis of complexes [Cu(DBPTA)4]BF4 (2) and
4.2. Synthesis of 1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane-
3,7-diylbis(phenylmethanone) DBPTA (1)
[CuX(DBPTA)3] (X = Br for complex 3 and X = I for complex 4)
The same procedure was utilized for the synthesis of com-
A Schlenk flask was charged with PTA (0.5 g, 3.3 mmol, plexes 2, 3 and 4. To an acetonitrile solution (10 mL) of 1
1 equiv.), sodium dodecyl sulfate (SDS, 20 mg), 15 mL of (200 mg, 0.56 mmol, 4 equiv.) was added an acetonitrile solu-
degassed water and 10 mL of degassed MeCN. In N2-atmo- tion (5 mL) of the copper(I) salt (0.14 mmol, 1 equiv., 44 mg of
sphere and at 5 °C, a 6 mL MeCN solution of benzoic anhy- [Cu(CH3CN)4]·BF4 for 2, 20 mg of CuBr for 3 and 26 mg of CuI
dride (1.49 g, 6.6 mmol, 2 equiv.) was added dropwise with for 4) dropwise with stirring for 30 min at room temperature.
stirring for 30 min. The produced solution was stirred at 5 °C The produced colourless solution was further stirred over-
for additional 1 h, and at room temperature (23 °C) overnight. night. The volume of the reaction mixture was then reduced
A saturated solution of sodium bicarbonate was then added under vacuum to ca. 2 mL. By the addition of petroleum ether
dropwise until the effervescence ceased (to convert the pro- (5 mL), a white solid of the product was formed, recovered by
duced benzoic acid to the water-soluble sodium salt). MeCN filtration, repeatedly washed with petroleum ether and dried
solvent was removed under vacuum, and the product (DBPTA) under vacuum.
was precipitated as a white solid, which was then filtered off,
[Cu(DBPTA)4]BF4 (2). Yield = 91.35% (200 mg) based on the
washed with distilled water and dried in vacuum.
metal salt. Elemental analysis calcd (%) for C76H80BCuF4N12O8P4·
Colourless crystals of DBPTA for SCXRD were obtained from 6H2O: C 54.6, H 5.55, N 10.05; found: C 54.46, H 5.5, N 9.82.
acetone solution by slow evaporation at room temperature.
FTIR (KBr): ν (cm−1) = 3450 br w, 2922 w, 2287 w, 2114 w, 1618
Yield = 38% (0.45 g) based on PTA. Elemental analysis calcd s, 1576 m, 1491 w, 1404 s, 1335 s, 1243 s, 1126 m, 1075 m,
(%) for C19H20N3O2P: C 64.58, H 5.7, N 11.89; found: C 64.22, 1000 s, 925 w, 885 w, 856 w, 786 m, 697 s, 650 m, 506 m, 432
1
H 5.68, N 11.51. FTIR (KBr): ν (cm−1) = 2919 w, 2204 w, 2117 w, w. H NMR (300 MHz, DMSO-d6, δ)/COSY: 7.48 (br s, 40H, Ar–
2
1622 s, 1576 m, 1489 w, 1445 m, 1405 s, 1337 s, 1245 s, H), 5.25 (d, JHH = 12.3 Hz, 4H, NCH2N), 5.08 (d, J = 14.1 Hz,
1213 m, 1130 m, 1075 s, 1029 m, 1000 s, 926 w, 882 m, 850 m, 4H, PCH2N), 4.72 (br s, 8H, NCH2N), 4.23–4.09 (m, 4H NCH2N,
795 m, 775 m, 727 s, 703 s, 646 m, 634 m, 533 w, 483 w, 427 w. 8H PCH2N), 3.72 (d, J = 12.9 Hz, 4H, PCH2N), 3.53 (d, J = 15.9
1H NMR (400 MHz, CDCl3, δ)/COSY: 7.56–7.41 (m, 10H, Ar–H), Hz, 8H, PCH2N). 31P{1H} NMR (300 MHz, DMSO-d6, δ): −59.98
2
5.57 (d, JHH = 14 Hz, 1H, NCH2N), 5.27 (d, J = 16 Hz, 1H, (br s). 13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC:
2
2
PCH2N), 4.98 (d, JHH = 13.2 Hz, 1H, NCH2N), 4.63 (d, JHH
=
169.68 (C–O), 169.5 (C–O), 134.91 (Cquat–Ph), 134.8 (Cquat–Ph),
13.2 Hz, 1H, NCH2N), 4.36 (d, J = 15.2 Hz, 1H, PCH2N), 4.17 (d, 130.17 (HC–Ph), 129.83 (HC–Ph), 128.48 (HC–Ph), 128.36 (HC–
2
2
2JHH = 13.6 Hz, 1H, NCH2N), 3.73 (dd, JHP = 14.8 Hz, JHH
=
Ph), 128.1 (HC–Ph), 127.52 (HC–Ph), 68.17 (NCH2N), 61.64
14.4 Hz, 1H, PCH2N), 3.53 (m, 3H, PCH2N). 31P{1H} NMR (NCH2N), 46.37 (PCH2N), 45.11 (PCH2N), 38.56 (PCH2N). DEPT
(400 MHz, CDCl3, δ): −77.86. 13C{1H} NMR (400 MHz, CDCl3, (300 MHz, DMSO-d6, δ): 129.91, 129.6, 128.23, 128.1, 127.86,
δ)/DEPT/HSQC: 171.62 (C–O), 171.03 (C–O), 135.33 (Cquat–Ph), 127.26, 67.91, 61.37, 46.14, 44.88, 38.27. ESI(+)MS in MeOH
135.11 (Cquat–Ph), 130.07 (HC–Ph), 129.85 (HC–Ph), 128.9 (HC– (m/z assignment, % intensity): 1474 ([Cu{DBPTA}4]+, 33),
Ph), 128.61 (HC–Ph), 127.92 (HC–Ph), 127.37 (HC–Ph), 69.13 1122 ([Cu{DBPTA}3]+, 45), 801 ([Cu{DBPTA}2 + MeOH]+, 15),
1
(NCH2N), 62.82 (NCH2N), 46.79 (d, JPC = 62.8, PCH2N), 44.72 769 ([Cu{DBPTA}2]+, 100).
1
1
(d, JPC = 103.2, PCH2N), 37.71 (d, JPC = 107.2, PCH2N). DEPT
(400 MHz, CDCl3, δ): 129.87, 129.64, 128.7, 128.4, 127.72,
[CuBr(DBPTA)3] (3)
127.16, 68.92, 62.6, 46.58, 44.52, 37.5. 1H NMR (400 MHz, Yield = 97.9% (165 mg) based on the metal salt. Elemental
2
DMSO-d6, δ)/COSY: 7.49–7.41 (m, 10H, Ar–H), 5.27 (d, JHH
=
analysis calcd (%) for C57H60BrCuN9O6P3: C 56.88, H 5.02,
13.6 Hz, 1H, NCH2N), 4.96 (d, J = 15.6 Hz, 1H, PCH2N), 4.78 (d, N 10.47; found: C 57.07, H 5.4, N 10.61. FTIR (KBr): ν (cm−1) =
2JHH = 13.2 Hz, 1H, NCH2N), 4.65 (d, JHH = 12.8 Hz, 1H, 2916 w, 2287 w, 2112 w, 1905 w, 1613 s, 1574 m, 1490 w, 1404
2
2
NCH2N), 4.21 (d, JHH = 13.6 Hz, 1H, NCH2N), 4.06 (d, J = 14.8 s, 1334 s, 1242 s, 1212 m, 1127 m, 1076 s, 1027 w, 999 s, 923 w,
Hz, 1H, PCH2N), 3.93 (dd, JHP = 14.4 Hz, JHH = 13.6 Hz, 1H, 881 m, 849 m, 780 s, 697 s, 648 m, 507 w. H NMR (400 MHz,
1
2
1
6120 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
2
CDCl3, δ)/COSY: 7.54–7.43 (m, 30H, Ar–H), 5.53 (d, JHH = 12.4 (C–O), 169.36 (C–O), 135.12 (Cquat–Ph), 129.78 (HC–Ph), 129.6
Hz, 3H, NCH2N), 5.21 (d, J = 14.4 Hz, 3H, PCH2N), 4.94 (d, (HC–Ph), 128.4 (HC–Ph), 128.18 (HC–Ph), 127.82 (HC–Ph),
2
2JHH = 11.2 Hz, 3H, NCH2N), 4.61 (d, JHH = 10.4 Hz, 3H, 127.28 (HC–Ph), 68.14 (NCH2N), 61.71 (NCH2N), 46.48
2
NCH2N), 4.34 (d, J = 14.8 Hz, 3H, PCH2N), 4.12 (d, JHH = 11.2 (PCH2N), 45.26 (PCH2N), 38.24 (PCH2N). DEPT (400 MHz,
Hz, 3H, NCH2N), 3.78 (m, 3H, PCH2N), 3.54 (br s, 9H, PCH2N). DMSO-d6, δ): 129.52, 129.34, 128.15, 127.93, 127.57, 127.02,
31P{1H} NMR (400 MHz, CDCl3, δ): −78.61 (br s). 13C{1H} NMR 67.88, 61.44, 46.25, 44.99, 37.98. ESI(+)MS in MeOH (m/z
(400 MHz, CDCl3, δ)/DEPT/HSQC: 171.44 (C–O), 171.08 (C–O), assignment,
%
intensity): 769 ([Cu{DBPTA}2]+, 12), 414
135.02 (Cquat–Ph), 134.79 (Cquat–Ph), 130.32 (HC–Ph), 130.05 ([Cu{DBPTA}]+, 100), 354 ([{DBPTA} + H]+, 25).
(HC–Ph), 128.94 (HC–Ph), 128.65 (HC–Ph), 128.03 (HC–Ph),
4.4. Synthesis of [Cu(μ-Br)(DBPTA)2]2 (5)
127.48 (HC–Ph), 69.01 (NCH2N), 62.67 (NCH2N), 47.04
(PCH2N), 45.25 (PCH2N), 38.13 (PCH2N). DEPT (400 MHz, To an acetonitrile solution (5 mL) of CuBr (20 mg, 0.14 mmol,
CDCl3, δ): 130.01, 129.84, 128.74, 128.45, 127.82, 127.26, 68.81, 1 equiv.) was added an acetonitrile solution (5 mL) of 1
62.47, 46.83, 45.02, 37.89. 1H NMR (300 MHz, DMSO-d6, (100 mg, 0.28 mmol, 2 equiv.) dropwise with stirring for
2
δ)/COSY: 7.43 (br s, 30H, Ar–H), 5.25 (d, JHH = 13.2 Hz, 3H, 30 min at room temperature. The produced colourless solution
2
NCH2N), 4.98 (d, J = 15.3 Hz, 3H, PCH2N), 4.77 (d, JHH = 12 was stirred at room temperature overnight, and then the reac-
2
Hz, 3H, NCH2N), 4.65 (d, JHH = 12.6 Hz, 3H, NCH2N), tion mixture was reduced under vacuum to ca. 2 mL. 5 mL of
4.23–4.09 (m, 3H NCH2N, 3H PCH2N), 3.94 (dd, 2JHP = 13.2 Hz, petroleum ether were added to produce compound 5 as a
2JHH = 7.8 Hz, 3H, PCH2N), 3.59 (br s, 9H, PCH2N). 31P{1H} white solid, which was then filtered off, repeatedly washed
NMR (400 MHz, DMSO-d6, δ): −63.22 (br s). 13C{1H} NMR with petroleum ether and dried under vacuum.
(300 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.76 (C–O), 169.37
Yield = 73.9% (88 mg) based on the metal salt. Elemental
(C–O), 135.34 (Cquat–Ph), 129.68 (HC–Ph), 129.49 (HC–Ph), analysis calcd (%) for C76H80Br2Cu2N12O8P4: C 53.68, H 4.74,
128.41 (HC–Ph), 128.16 (HC–Ph), 127.79 (HC–Ph), 127.22 (HC– N 9.89; found: C 53.36, H 5.01, N 9.59. FTIR (KBr): ν (cm−1) =
Ph), 68.12 (NCH2N), 61.74 (NCH2N), 45.64 (PCH2N), 44.48 2281 w, 2116 w, 1905 w, 1614 s, 1575 m, 1490 w, 1404 m,
(PCH2N), 37.59 (PCH2N). DEPT (300 MHz, DMSO-d6, δ): 1336 m, 1238 m, 1126 w, 1075 m, 1001 m, 921 w, 889 w, 858 w,
129.43, 129.25, 128.16, 127.9, 127.54, 126.97, 67.94, 61.48, 787 m, 698 s, 651 m, 509 m. 1H NMR (400 MHz, CDCl3, δ):
45.38, 44.24, 37.32. ESI(+)MS in MeOH (m/z assignment, 7.53–7.43 (m, 40H, Ar–H), 5.47 (d, 2JHH = 11.2 Hz, 4H, NCH2N),
2
% intensity): 1474 ([Cu{DBPTA}4]+, 13), 1153 ([Cu{DBPTA}3
+
5.16 (d, J = 15.6 Hz, 4H, PCH2N), 4.88 (d, JHH = 8 Hz, 4H,
MeOH]+, 19), 801 ([Cu{DBPTA}2
+
MeOH]+, 22), 769 NCH2N), 4.61 (br s, 4H, NCH2N), 4.37 (d, J = 10.8 Hz, 4H,
([Cu{DBPTA}2]+, 27), 354 ([{DBPTA} + H]+, 13).
PCH2N), 4.09–4.03 (m, 4H, NCH2N), 3.83 (br s, 4H, PCH2N),
3.59–3.5 (m, 12H, PCH2N). 31P{1H} NMR (400 MHz, CDCl3, δ):
[CuI(DBPTA)3] (4)
1
−66.77 (br s). H NMR (400 MHz, DMSO-d6, δ)/COSY: 7.46 (br
Yield = 97.1% (170 mg) based on the metal salt. Elemental s, 40H, Ar–H), 5.23 (d, 2JHH = 12.8 Hz, 4H, NCH2N), 5.00 (d, J =
2
analysis calcd (%) for C57H60CuIN9O6P3: C 54.75, H 4.84, N 14.4 Hz, 4H, PCH2N), 4.77 (d, JHH = 8.4 Hz, 4H, NCH2N), 4.64
10.08; found: C 55.05, H 5.01, N 10.05. FTIR (KBr): ν (cm−1) = (d, JHH = 11.2 Hz, 4H, NCH2N), 4.23–4.14 (m, 4H NCH2N, 4H
2
2918 w, 1616 s, 1575 m, 1491 w, 1404 s, 1334 s, 1241 s, PCH2N), 3.93 (d, J = 11.2 Hz, 4H, PCH2N), 3.6 (br s, 12H,
1178 m, 1126 m, 1075 s, 1027 w, 1000 s, 923 w, 882 m, 853 m, PCH2N). 31P{1H} NMR (400 MHz, DMSO-d6, δ): −63.75 (br s).
785 s, 697 s, 650 m, 507 m. 1H NMR (300 MHz, CDCl3, 13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.68
2
δ)/COSY: 7.54–7.44 (m, 30H, Ar–H), 5.48 (d, JHH = 12 Hz, 3H, (C–O), 169.37 (C–O), 135.08 (Cquat–Ph), 129.81 (HC–Ph), 129.65
2
NCH2N), 5.14 (d, J = 14.4 Hz, 3H, PCH2N), 4.9 (d, JHH = 10.5 (HC–Ph), 128.42 (HC–Ph), 128.17 (HC–Ph), 127.85 (HC–Ph),
2
Hz, 3H, NCH2N), 4.59 (d, JHH = 8.7 Hz, 3H, NCH2N), 4.32 (d, 127.26 (HC–Ph), 68.1 (NCH2N), 61.67 (NCH2N), 46.12 (PCH2N),
2
J = 13.8 Hz, 3H, PCH2N), 4.08 (d, JHH = 13.2 Hz, 3H, NCH2N), 44.84 (PCH2N), 37.99 (PCH2N). DEPT (400 MHz, DMSO-d6, δ):
3.84 (d, J = 12 Hz, 3H, PCH2N), 3.53 (br s, 9H, PCH2N). 31P{1H} 129.56, 129.39, 128.17, 127.92, 127.6, 127.01, 67.87, 61.41,
NMR (300 MHz, CDCl3, δ): −67.66 (br s). 13C{1H} NMR 45.87, 44.6, 37.73. ESI(+)MS in DMF (m/z assignment, % inten-
(300 MHz, CDCl3, δ)/DEPT/HSQC: 171.16 (C–O), 134.68 (Cquat
–
sity): 769 ([Cu{DBPTA}2]+, 5), 642 ([Cu2Br2{DBPTA} + H]+, 14),
Ph), 134.43 (Cquat–Ph), 130.55 (HC–Ph), 130.26 (HC–Ph), 562 ([Cu2Br{DBPTA}]+, 21), 414 ([Cu{DBPTA}]+, 67).
128.96 (HC–Ph), 128.7 (HC–Ph), 128.11 (HC–Ph), 127.56 (HC–
4.5. Synthesis of [Cu(μ-I)(DBPTA)2]2 (6)
Ph), 68.9 (NCH2N), 62.53 (NCH2N), 47.76 (PCH2N), 46.01
(PCH2N), 38.7 (PCH2N). DEPT (300 MHz, CDCl3, δ): 130.33, To an acetonitrile solution (5 mL) of CuI (26 mg, 0.14 mmol,
130.04, 128.75, 128.49, 127.90, 127.35, 68.7, 62.32, 47.59, 1 equiv.) was added an acetonitrile solution (5 mL) of 1
45.86, 38.49. 1H NMR (400 MHz, DMSO-d6, δ)/COSY: 7.45 (br s, (100 mg, 0.28 mmol, 2 equiv.) dropwise with stirring for
2
30H, Ar–H), 5.24 (d, JHH = 12.8 Hz, 3H, NCH2N), 5.01 (d, J = 30 min at room temperature. The produced colourless solu-
2
15.2 Hz, 3H, PCH2N), 4.77 (d, JHH = 11.6 Hz, 3H, NCH2N), tion was stirred at room temperature, and within a few
2
4.65 (d, JHH = 12 Hz, 3H, NCH2N), 4.23–4.14 (m, 3H NCH2N, minutes, a white precipitate of 6 was observed. The solution
3H PCH2N), 3.91 (d, J = 13.2 Hz, 3H, PCH2N), 3.59 (m, 9H, was stirred for further 3 h, and then the resulting white
PCH2N). 31P{1H} NMR (400 MHz, DMSO-d6, δ): −65.88 (br s). product was filtered off, repeatedly washed with diethyl ether
13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.69 and dried in vacuum.
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6121

View Article Online
Paper
Dalton Transactions
Yield = 74% (93 mg) based on the metal salt. Elemental ESI(+)MS in MeOH (m/z assignment,
% intensity): 572
analysis calcd (%) for C76H88Cu2I2N12O12P4·4H2O: C 48.91, ([Cu{bpy}{DBPTA}]+, 100%), 375 ([Cu{bpy}2]+, 7%), 219
H 4.75, N 9.01; found: C 48.72, H 4.48, N 8.90. FTIR (KBr): ([Cu{bpy}]+, <5%).
ν (cm−1) = 2090 w, 1612 s, 1446 w, 1411 m, 1347 m, 1292 w,
4.7. Synthesis of [Cu(bpy)(DBPTA)2]BPh4 (8)
1235 m, 1199 w, 1130 w, 1089 m, 1004 m, 917 w, 891 w, 864 w,
784 m, 720 m, 698 s, 650 m, 587 w, 511 m, 438 w. 1H NMR To an acetonitrile solution (15 mL) of CuBr (20 mg,
(400 MHz, DMSO-d6, δ)/COSY: 7.47–7.43 (m, 40H, Ar–H), 5.23 0.14 mmol, 1 equiv.) was added an acetonitrile solution
2
(d, JHH = 13.2 Hz, 4H, NCH2N), 5.0 (d, J = 15.6 Hz, 4H, (5 mL) of 1 (100 mg, 0.28 mmol, 2 equiv.) dropwise with stir-
2
2
PCH2N), 4.82 (d, JHH = 12.4 Hz, 4H, NCH2N), 4.64 (d, JHH
=
ring for 30 min at room temperature. The mixture was
12.4 Hz, 4H, NCH2N), 4.24–4.16 (m, 4H NCH2N, 4H PCH2N), further stirred at room temperature for 1 h, then 2,2′-bipyri-
3.94 (d, J = 12.4 Hz, 4H, PCH2N), 3.63 (br s, 12H, PCH2N). dine (22 mg, 0.14 mmol, 1 equiv.) was added. An ethanol
31P{1H} NMR (400 MHz, DMSO-d6, δ): −69.14 (br s). 13C{1H} (10 mL) solution of NaBPh4 (48 mg, 0.14 mmol, 1 equiv.)
NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.8 (C–O), 169.53 was added and the produced reaction mixture was stirred
(C–O), 135.15 (Cquat–Ph), 135.06 (Cquat–Ph), 129.93 (HC–Ph), overnight. The reaction mixture was then reduced under
129.74 (HC–Ph), 128.51 (HC–Ph), 128.25 (HC–Ph), 127.93 vacuum to ca. 2 mL. 5 mL of petroleum ether were added to
(HC–Ph), 127.31 (HC–Ph), 68.20 (NCH2N), 61.76 (NCH2N), produce compound 8 as a pale yellow solid, which was then
46.45 (PCH2N), 45.16 (PCH2N), 38.30 (PCH2N). DEPT filtered off, repeatedly washed with petroleum ether and
(400 MHz, DMSO-d6, δ): 129.67, 129.48, 128.26, 128.0, dried under vacuum.
127.67, 127.06, 67.93, 61.5, 46.18, 44.91, 38.04. ESI(+)MS in
Yield = 34.4% (60 mg) based on the metal salt. Elemental
DMF (m/z assignment, % intensity): 959 ([Cu2I{DBPTA}2]+, 5), analysis calcd (%) for C72H68BCuN8O4P2·2H2O: C 67.47, H
769 ([Cu{DBPTA}2]+, 7), 734 ([Cu2I2{DBPTA} + H]+, 13), 414 5.66, N 8.74; found: C 67.78, H 5.32, N 8.43. FTIR (KBr): ν
([Cu{DBPTA}]+, 70), 354 ([{DBPTA} + H]+, 8).
(cm−1) = 3054 w, 2113 w, 1625 s, 1577 m, 1472 w, 1407 m,
1337 m, 1245 m, 1126 w, 1077 m, 1002 m, 887 w, 856 w,
764 m, 733 m, 702 s, 651 m, 611 m, 509 w. 1H NMR (300 MHz,
4.6. Synthesis of [Cu(bpy)(DBPTA)2]BF4 (7)
To an acetonitrile solution (15 mL) of [Cu(MeCN)4]BF4 (88 mg, DMSO-d6, δ)/COSY: 7.42 (br s, 20H, Ar–H), 7.19 (br s, 12H, Ar–
2
0.28 mmol, 1 equiv.) was added an acetonitrile solution H), 6.93 (br s, 10H, Ar–H), 6.79 (br s, 6H, Ar–H), 5.2 (d, JHH
=
(15 mL) of 1 (200 mg, 0.56 mmol, 2 equiv.) dropwise with stir- 12.9 Hz, 2H, NCH2N), 5.02 (d, J = 14.7 Hz, 2H, PCH2N), 4.73 (d,
2
ring for 30 min at room temperature. The mixture was stirred 2JHH = 11.7 Hz, 2H, NCH2N), 4.62 (d, JHH = 12 Hz, 2H,
2
at room temperature overnight, then 2,2′-bipyridine (44 mg, NCH2N), 4.15 (d, JHH = 12.6 Hz, 2H, NCH2N), 4.03 (d, 2H, J =
0.28 mmol, 1 equiv.) was added in solid portions. The pro- 14.7 Hz, PCH2N), 3.89 (d, J = 12.6 Hz, 2H, PCH2N), 3.61 (m,
duced clear yellow solution was stirred for a further 6 h at 6H, PCH2N). 31P{1H} NMR (300 MHz, DMSO-d6, δ): −64.13 (br
room temperature, and then its volume was reduced under s). 13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.44
vacuum to ca. 2 mL to afford complex 7 as a bright green solid. (C–O), 164.33 (Cquat), 163.68 (Cquat), 163.02 (Cquat), 162.37
The product was then filtered off, repeatedly washed with (Cquat), 135.54 (HC–Ph), 134.94 (Cquat), 129.89 (HC–Ph), 129.71
diethyl ether and dried in vacuum.
(HC–Ph), 128.37 (HC–Ph), 128.15 (HC–Ph), 127.93 (HC–Ph),
Yield = 65.56% (186 mg) based on the metal salt. Elemental 127.27 (HC–Ph), 125.36 (HC–Ph), 125.33 (HC–Ph), 125.29
analysis calcd (%) for C48H48BCuF4N8O4P2·2H2O: C 54.94, H (HC–Ph), 125.26 (HC–Ph), 121.53 (HC–Ph), 68.12 (NCH2N),
5.00, N 10.68; found: C 54.58, H 4.74, N 10.36. FTIR (KBr): 61.59 (NCH2N), 44.99 (PCH2N), 43.90 (PCH2N), 37.24 (PCH2N).
ν (cm−1) = 3485 br w, 2286 w, 2113 w, 1619 s, 1576 m, 1491 w, DEPT (300 MHz, DMSO-d6, δ): 135.28, 129.63, 129.45, 128.13,
1407 m, 1337 s, 1245 m, 1052 s, 1001 s, 880 w, 858 w, 765 m, 127.9, 127.68, 127.03, 125.11, 125.08, 125.04, 125.01, 121.28,
1
699 s, 652 m, 509 m. H NMR (300 MHz, DMSO-d6, δ)/COSY: 67.85, 61.36, 44.71, 43.61, 37.0. ESI(+)MS in MeOH (m/z
8.8 (br s, 2H, bpy-H6,6′), 8.58 (br s, 2H, bpy-H3,3′), 8.17 (br s, assignment, % intensity): 572 ([Cu{bpy}{DBPTA}]+, 100%), 375
2H, bpy-H5,5′), 7.67 (br s, 2H, bpy-H4,4′), 7.42 (s, 20H, Ar–H), ([Cu{bpy}2]+, 34%), 219 ([Cu{bpy}]+, 9%).
2
5.2 (d, JHH = 12.9 Hz, 2H, NCH2N), 5.01 (d, J = 14.7 Hz, 2H,
2
2
4.8. Synthesis of [Ag(DBPTA)4]NO3 (9)
PCH2N), 4.76 (d, JHH = 12.6 Hz, 2H, NCH2N), 4.62 (d, JHH
=
2
12.6 Hz, 2H, NCH2N), 4.16 (d, JHH = 12.6 Hz, 2H, NCH2N), A 100 mL round bottom flask was charged with 1 (100 mg,
3.98 (m, 4H, PCH2N), 3.62 (m, 6H, PCH2N). 31P{1H} NMR 0.28 mmol, 4 equiv.), acetonitrile (18 mL) and aqueous
(300 MHz, DMSO-d6, δ): −64.01 (br s). 13C{1H} NMR (400 MHz, NH4OH solution (1 M, 2 mL). Under continuous stirring,
DMSO-d6, δ)/DEPT/HSQC: 169.48 (C–O), 151.18 (bpy–Cquat1,1′), AgNO3 (12 mg, 0.07 mmol, 1 equiv.) in acetonitrile (18 mL)
149.6 (bpy–HC6,6′), 138.93 (bpy–HC5,5′), 134.94 (Cquat–Ph), was added dropwise for 30 min at room temperature. The
129.9 (HC–Ph), 129.73 (HC–Ph), 128.39 (HC–Ph), 128.17 obtained colourless solution was further stirred for 2 h, then
(HC–Ph), 127.95 (HC–Ph), 127.29 (HC–Ph), 125.98 (bpy–HC4,4′), neutralized with aqueous HNO3 (1 M). The volume of the reac-
122.58 (bpy–HC3,3′), 68.12 (NCH2N), 61.59 (NCH2N), 44.87 tion mixture was then reduced under vacuum to ca. 4 mL. The
(PCH2N), 43.82 (PCH2N), 37.24 (PCH2N). DEPT (300 MHz, obtained white solid of the product was recovered by filtration,
DMSO-d6, δ): 149.55, 138.72, 129.7, 129.52, 128.19, 127.96, repeatedly washed with petroleum ether, and dried under
127.76, 127.09, 125.73, 122.36, 67.9, 61.36, 44.67, 43.60, 36.94. vacuum.
6122 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
Yield = 70.4% (78 mg) based on the metal salt. Elemental 14.03, 10.58 (3,5-CH3). DEPT (300 MHz, DMSO-d6, δ): 129.83,
analysis calcd (%) for C76H80AgN13O11P4·3H2O: C 55.75, H 129.54, 128.26, 128.02, 127.87, 127.12, 106.61, 68.92, 68.10,
5.29, N 11.12; found: C 55.59, H 5.22, N 11.07. FTIR (KBr): 61.53, 45.82, 44.87, 37.86, 37.86, 13.77, 10.32. ESI(+)MS in
ν (cm−1) = 3449 br m, 1616 s, 1576 m, 1492 w, 1407 s, 1334 s, MeOH (m/z assignment,
% intensity): 758 ([Ag{Tpm*}
1244 s, 1128 m, 1078 m, 1028 w, 1001 m, 926 w, 858 w, 787 m, {DBPTA}]+, 100), 405 ([Ag{Tpm*}]+, 16).
698 s, 651 m, 504 w. 1H NMR (300 MHz, DMSO-d6, δ)/COSY:
2
4.10. Synthesis of [Ag(Tpms)(DBPTA)] (11)
7.43 (br s, 40H, Ar–H), 5.20 (d, JHH = 13.5 Hz, 4H, NCH2N),
5.06 (d, J = 15.3 Hz, 4H, PCH2N), 4.64 (br s, 8H, NCH2N), 4.22 To a methanol solution (20 mL) of AgNO3 (48 mg, 0.28 mmol,
(d, J = 13.8 Hz, 4H PCH2N), 4.06 (m, 4H PCH2N, 4H NCH2N), 1 equiv.) was added a methanol solution (10 mL) of 1 (100 mg,
3.60 (br s, 12H, PCH2N). 31P{1H} NMR (300 MHz, DMSO-d6, δ): 0.28 mmol, 1 equiv.) dropwise with stirring for 30 minutes at
−59.62 (br s). 13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/ room temperature. The colourless mixture was further stirred
HSQC: 169.71 (C–O), 169.54 (C–O), 134.97 (Cquat–Ph), 131.91 at room temperature for 1 h, then a methanol solution (20 mL)
(Cquat–Ph), 130.04 (HC–Ph), 128.66 (HC–Ph), 128.46 (HC–Ph), of Li-Tpms (84 mg, 0.28 mmol, 1 equiv.) was added dropwise.
128.27 (HC–Ph), 128.11 (HC–Ph), 127.42 (HC–Ph), 68.23 The obtained colourless solution was further stirred overnight
(NCH2N), 61.63 (NCH2N), 45.88 (PCH2N), 44.69 (PCH2N), 37.91 and was then reduced under vacuum to ca. 2 mL. 10 mL of
(PCH2N). DEPT (300 MHz, DMSO-d6, δ): 131.68, 129.80, 129.49, methylene chloride were added to produce compound 12 as a
128.41, 128.21, 128.02, 127.85, 127.17. ESI(+)MS in MeOH grey solid, which was then filtered off, repeatedly washed with
(m/z assignment, % intensity): 1016 ([Ag2{DBPTA}2 + NO3
MeOH]+, 100), 845 ([Ag{DBPTA}2 MeOH]+, 22), 813
([Ag{DBPTA}2]+, 7), 354 ([DBPTA + H+], 43).
+
petroleum ether and dried under vacuum.
+
Yield = 62.77% (133 mg) based on the metal salt. Elemental
analysis calcd (%) for C29H29AgN9O5PS·2H2O·MeOH: C 44.51,
H 4.70, N 15.07, S 3.83; found: C 44.62, H 4.57, N 14.84, S 3.62.
FTIR (KBr): ν (cm−1) = 3491 br w, 1619 s, 1540 m, 1408 m,
4.9. Synthesis of [Ag(Tpm*)(DBPTA)]NO3 (10)
To a methanol solution (10 mL) of AgNO3 (34 mg, 0.2 mmol, 1 1337 m, 1244 s, 1128 w, 1099 m, 1076 m, 1043 m, 1002 m, 898
equiv.) was added a methanol solution (5 mL) of 1 (94 mg, w, 759 m, 700 m, 653 w, 626 s, 533 m. H NMR (400 MHz,
0.27 mmol, 1.3 equiv.) dropwise with stirring for 30 minutes at DMSO-d6, δ)/COSY: 8.06 (d, J = 2.4 Hz, 3H, 5-H-pz), 7.59 (d, J =
room temperature. The mixture was further stirred for another 1.2 Hz, 3H, 3-H-pz), 7.53–7.45 (m, 10H, Ar–H), 6.40 (dd, J = 2.4
2
30 minutes, then a methanol solution (5 mL) of Tpm* (61 mg, Hz, J = 1.2 Hz, 3H, 4-H-pz), 5.23 (d, JHH = 13.6 Hz, 1H
2
0.2 mmol, 1 equiv.) was added dropwise. The obtained reac- NCH2N), 5.14 (d, J = 14 Hz, 1H, PCH2N), 4.91 (d, JHH = 13.2,
2
tion mixture was stirred overnight and was then reduced under 1H, NCH2N), 4.67 (d, JHH = 13.2, 1H, NCH2N), 4.29 (m, 1H
vacuum to ca. 2 mL to afford compound 11 as a pale yellow PCH2N, 1H NCH2N), 4.20 (d, J = 6.4, 1H, PCH2N), 3.84 (br s,
solid, which was filtered off, repeatedly washed with petroleum 3H, PCH2N). 31P{1H} NMR (400 MHz, DMSO-d6, δ): −56.17 (br
ether and dried under vacuum.
s). 13C{1H} NMR (400 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.82
Yield = 66.94% (110 mg) based on the metal salt. Elemental (C–O), 169.57 (C–O), 140.90 (3-C-pz), 135.11 (Cquat–Ph), 134.87
analysis calcd (%) for C35H42AgN10O5P·3H2O: C 48.01, H 5.53, (Cquat–Ph), 133.15 (5-C-pz), 130.02 (HC–Ph), 129.78 (HC–Ph),
N 16.00; found: C 48.30, H 5.24, N 15.79. FTIR (KBr): ν (cm−1
)
128.59 (HC–Ph), 128.20 (HC–Ph), 128.06 (HC–Ph), 127.36 (HC–
= 1618 m, 1562 m, 1409 m, 1333 s, 1303 s, 1248 s, 1127 w, Ph), 106.59 (4-C-pz), 95.05 (CSO3), 68.24 (NCH2N), 61.73
1079 m, 1031 m, 1002 m, 897 w, 855 m, 787 m, 701 s, 652 m, (NCH2N), 45.71 (d, 1JPC = 40 Hz, PCH2N), 44.52 (PCH2N), 37.64
1
517 m, 477 w. H NMR (300 MHz, CDCl3, δ): 7.79 (s, 1H, HC (PCH2N). DEPT (400 MHz, DMSO-d6, δ): 140.66, 132.90, 129.77,
{3,5-Me2pz}3), 7.58–7.43 (m, 10H, Ar–H), 5.90 (s, 3H, 4-H-pz), 129.53, 128.34, 127.95, 127.81, 127.11, 106.34, 68.00, 61.47,
5.48 (d, 1H NCH2N, 1H PCH2N), 4.96 (br S, 2H, NCH2N), 4.58 45.46, 44.22, 37.39. ESI(+)MS in MeOH (m/z assignment, %
(d, J = 14.4 Hz, 1H PCH2N), 4.39 (m, 1H NCH2N, 1H PCH2N), intensity): 1615 ([Ag3{Tpms}2{DBPTA}2]+, 18), 1568 ([Ag2{Tpms}
4.08 (br S, 3H, PCH2N), 2.44, 2.13 (s, s, 9H, 9H, 3,5-Me). 31P {DBPTA}3]+, 7), 1215 ([Ag2{Tpms}{DBPTA}2]+, 100), 862
{1H} NMR (300 MHz, CDCl3, δ): −56.21 (br s).1H NMR ([Ag2{Tpms}{DBPTA}]+, 13), 813 ([Ag{DBPTA}2]+, 12), 460
(300 MHz, DMSO-d6, δ)/COSY: 7.90 (s, 1H, HC{3,5-Me2pz}3), ([Ag{DBPTA}]+, 15).
7.49 (br s, 10H, Ar–H), 6.14 (s, 3H, 4-H-pz), 5.33 (m, 1H
2
4.11. X-ray structure determination of compound 1
NCH2N, 1H PCH2N), 5.00 (d, JHH = 13.2 Hz, 1H, NCH2N), 4.74
2
(d, JHH = 13.5, 1H, NCH2N), 4.44 (m, 2H PCH2N, 1H NCH2N), A crystal of 1 was immersed in cryo-oil and mounted in a
4.08 (br S, 3H PCH2N), 2.44, 2.13 (s, s, 9H, 9H, 3,5-Me). 31P{1H} Nylon loop. Intensity data were collected at ambient tempera-
NMR (300 MHz, DMSO-d6, δ): −54.64 (br s). 13C{1H} NMR ture on a Bruker AXS-KAPPA APEX II PHOTON 100 diffract-
(300 MHz, DMSO-d6, δ)/DEPT/HSQC: 169.87 (C–O), 169.69 ometer with graphite monochromated Mo-Kα (0.71069 Å) radi-
(C–O), 150.39 (5-Cquat-pz), 141.73 (3-Cquat-pz), 135.10 (Cquat
–
ation. A full sphere of data were obtained using omega scans
Ph), 134.93 (Cquat–Ph), 130.09 (HC–Ph), 129.78 (HC–Ph), of 0.5° per frame. Cell parameters were retrieved using Bruker
128.52 (HC–Ph), 128.28 (HC–Ph), 128.13 (HC–Ph), 127.38 (HC– SMART56 software, refined with Bruker SAINT56 on all the
Ph), 106.87 (4-C-pz), 69.18 (HC{3,5-Me2pz}3), 68.38 (NCH2N), observed reflections and for the th absorption corrections the
1
61.81 (NCH2N), 46.01 (d, JPC = 43.5 Hz, PCH2N), 45.11 (d, SADABS program57 was applied. The structures were solved by
1
1JPC = 31.2 Hz, PCH2N), 38.16 (d, JPC = 43.8 Hz, PCH2N), direct methods using SIR2014 package58 and refined with
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6123

View Article Online
Paper
Dalton Transactions
SHELXL-2018/3.59 Calculations were performed using the authors acknowledge the Portuguese NMR Network (IST-UL
WinGX System-Version 2018.3.60 The hydrogen atoms were Centre) for access to the NMR facility and the IST Node of the
included in calculated positions and refined by means of the Portuguese Network of Mass-spectrometry for the ESI-MS
riding-model approximation using Uiso(H) as 1.2Ueq of the measurements.
parent methylene and aromatic carbon atoms. Least square
refinements with anisotropic thermal motion parameters for
all the non-hydrogen atoms were employed.
References
Crystallographic data for the structural analysis have been
deposited to the Cambridge Crystallographic Data Center
(Cambridge, UK) (CCDC 2067383).
1 V. I. Siele, J. Heterocycl. Chem., 1977, 14, 337–339.
2 A. G. Mahmoud, M. F. C. Guedes da Silva and
A. J. L. Pombeiro, Coord. Chem. Rev., 2021, 429, 213614.
3 D. J. Darensbourg, C. G. Ortiz and J. W. Kamplain,
Organometallics, 2004, 23, 1747–1754.
4.12. General procedure for the cycloaddition of benzyl azide
and terminal alkynes
4 D. A. Krogstad, G. S. Ellis, A. K. Gunderson,
A. J. Hammrich, J. W. Rudolf and J. A. Halfen, Polyhedron,
2007, 26, 4093–4100.
5 L. Marvelli, V. Ferretti, V. Bertolasi, I. Lampronti,
R. Gambari, C. Trapella, G. Turrin, F. Bonotto,
A. Moriello and P. Bergamini, J. Inorg. Biochem., 2019, 199,
110787.
In a 10 mL cylindrical screw capped vial equipped with a small
magnetic stirring bar,
a mixture of acetylene derivative
(0.3 mmol, 1 equiv.), benzyl azide (0.3 mmol, 1 equiv.), the
catalyst (1–5 mol%) and 2 mL of the solvent was stirred. The
reaction proceeded at room temperature (23 °C), unless other-
wise noted, and the course of the reaction was monitored by
TLC.
6 A. Guerriero, M. Peruzzini and L. Gonsalvi, Coord. Chem.
Rev., 2018, 355, 328–361.
For reactions performed under microwave irradiation, the
aforementioned reaction mixture in 1.5 mL of solvent was
charged in a 10 mL glass vial sealed with an aluminium/Teflon
crimp top and equipped with a small magnetic stirring bar.
The mixture was irradiated in the microwave reactor to reach
125 °C for 15 minutes.
At the end of the reaction, water was added slowly until the
precipitate is completely formed the solution. The residue was
collected by filtration, washed with water and then petroleum
ether, and dried in air to furnish the product triazoles. The 1H
NMR spectra of all 1,2,3-triazole products proved their high
purity and the spectroscopic data (ESI, section 3†) are in agree-
ment with those already reported.33,47,61–65
7 F. Scalambra, P. Lorenzo-Luis, I. D. L. Ríos and
A. Romerosa, Eur. J. Inorg. Chem., 2019, 2019, 1529–1538.
8 A. G. Mahmoud, P. Smolénski, M. F. C. Guedes Da Silva
and A. J. L. Pombeiro, Molecules, 2020, 25, 5479.
9 V. V. Rostovtsev, L. G. Green, V. V. Fokin and
K. B. Sharpless, Angew. Chem., 2002, 114, 2708–2711.
10 C. W. Tornøe, C. Christensen and M. Meldal, J. Org. Chem.,
2002, 67, 3057–3064.
11 H. C. Kolb, M. G. Finn and K. B. Sharpless, Angew. Chem.,
Int. Ed., 2001, 40, 2004–2021.
12 D. D. Díaz, S. Punna, P. Holzer, A. K. Mcpherson,
K. B. Sharpless, V. V. Fokin and M. G. Finn, J. Polym. Sci.,
Part A: Polym. Chem., 2004, 42, 4392–4403.
4.13. General procedure for the cycloaddition of in situ
generated azides and terminal alkynes
13 J. A. Johnson, M. G. Finn, J. T. Koberstein and N. J. Turro,
Macromol. Rapid Commun., 2008, 29, 1052–1072.
14 E. Haldón, M. C. Nicasio and P. J. Pérez, Org. Biomol.
Chem., 2015, 13, 9528–9550.
15 P. Appukkuttan, W. Dehaen, V. V. Fokin and E. Van der
Eycken, Org. Lett., 2004, 6, 4223–4225.
The procedure described above for performing the reaction
under microwave irradiations was followed using substituted
benzyl bromide (0.3 mmol, 1 equiv.), acetylene derivative
(0.3 mmol, 1 equiv.) and NaN3 (0.33 mmol, 1.1 equiv.) as a
mixture of reactants.
16 E. F. V. Scriven and K. Turnbull, Chem. Rev., 1988, 88, 297–
368.
17 S. Bräse, C. Gil, K. Knepper and V. Zimmermann, Angew.
Chem., Int. Ed., 2005, 44, 5188–5240.
Conflicts of interest
18 A. G. Mahmoud, M. F. C. Guedes da Silva, J. Sokolnicki,
P. Smoleński and A. J. L. Pombeiro, Dalton Trans., 2018, 47,
7290–7299.
There are no conflicts to declare.
19 I. L. Librando, A. G. Mahmoud, S. A. C. Carabineiro,
M. F. C. Guedes da Silva, C. F. G. C. Geraldes and
A. J. L. Pombeiro, Catalysts, 2021, 11, 185.
Acknowledgements
This research was funded by the Fundação para a Ciência e a
Tecnologia (FCT), Portugal, project UIDB/00100/2020 of the 20 J. Sultana and D. Sarma, Catal. Rev., 2020, 62, 96–117.
Centro de Química Estrutural and by the RUDN University 21 J. McNulty, K. Keskar and R. Vemula, Chem. – Eur. J., 2011,
Strategic Academic Leadership Program. AGM was funded by
17, 14727–14730.
Instituto Superior Técnico, Portugal through the project 22 J. McNulty and K. Keskar, Eur. J. Org. Chem., 2012, 2012,
CO2usE-1801P.00867.1.01 (contract no. IST-ID/263/2019). The
5462–5470.
6124 | Dalton Trans., 2021, 50, 6109–6125
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
23 A. A. Ali, M. Chetia, B. Saikia, P. J. Saikia and D. Sarma, 43 S. Díez-González, A. Correa, L. Cavallo and S. P. Nolan,
Tetrahedron Lett., 2015, 56, 5892–5895. Chem. – Eur. J., 2006, 12, 7558–7564.
24 P. Y. Dapsens, C. Mondelli and J. Pérez-Ramírez, ACS 44 S. Díez-González and S. P. Nolan, Angew. Chem., 2008, 120,
Catal., 2012, 2, 1487–1499. 9013–9016.
25 H. W. Tan, A. R. Abdul Aziz and M. K. Aroua, Renewable 45 S. Díez-González, E. D. Stevens and S. P. Nolan, Chem.
Sustainable Energy Rev., 2013, 27, 118–127. Commun., 2008, 4747–4749.
26 C. A. G. Quispe, C. J. R. Coronado and J. A. Carvalho, 46 S. Özçubukçu, E. Ozkal, C. Jimeno and M. A. Pericàs, Org.
Renewable Sustainable Energy Rev., 2013, 27, 475–493.
27 Y. Gu and F. Jérôme, Green Chem., 2010, 12, 1127–1138.
28 A. E. Díaz-Álvarez, J. Francos, B. Lastra-Barreira, P. Crochet
and V. Cadierno, Chem. Commun., 2011, 47, 6208–6227.
29 C. Vidal and J. García-Álvarez, Green Chem., 2014, 16, 3515–
3521.
Lett., 2009, 11, 4680–4683.
47 E. Ozkal, S. Özçubukçu, C. Jimeno and M. A. Pericàs, Catal.
Sci. Technol., 2012, 2, 195–200.
48 F. Himo, T. Lovell, R. Hilgraf, V. V. Rostovtsev,
L. Noodleman, K. B. Sharpless and V. V. Fokin, J. Am.
Chem. Soc., 2005, 127, 210–216.
30 N. Nebra and J. García-Álvarez, Molecules, 2020, 25, 2015.
31 A. G. Mahmoud, M. F. C. Guedes da Silva, E. I. Śliwa,
49 V. D. Bock, H. Hiemstra and J. H. van Maarseveen,
Eur. J. Org. Chem., 2006, 2006, 51–68.
P. Smoleński, M. L. Kuznetsov and A. J. L. Pombeiro, Chem. 50 B. T. Worrell, J. A. Malik and V. V. Fokin, Science, 2013, 340,
– Asian J., 2018, 13, 2868–2880. 457–460.
32 A. G. Mahmoud, L. M. D. R. S. Martins, M. F. C. Guedes da 51 M. Rodríguez-Rodríguez, E. Gras, M. A. Pericàs and
Silva and A. J. L. Pombeiro, Inorg. Chim. Acta, 2018, 483,
371–378.
33 A. G. Mahmoud, M. F. C. Guedes da Silva, K. T. Mahmudov
M. Gómez, Chem. – Eur. J., 2015, 21, 18706–18710.
52 F. Nemati, M. M. Hosseini and H. Kiani, J. Saudi Chem.
Soc., 2016, 20, S503–S508.
and A. J. L. Pombeiro, Dalton Trans., 2019, 48, 1774– 53 D. J. Daigle, T. J. Decuir, J. B. Robertson and
1785.
D. J. Darensbourg, in Inorganic Syntheses, ed.
M. Y. Darensbourg, John Wiley & Sons, Ltd, 32nd edn,
1998, pp. 40–45.
34 F. Tisato, F. Refosco, M. Porchia, M. Tegoni, V. Gandin,
C. Marzano, M. Pellei, G. Papini, L. Lucato, R. Seraglia and
P. Traldi, Rapid Commun. Mass Spectrom., 2010, 24, 1610– 54 R. Wanke, P. Smoleński, M. F. C. Guedes da Silva,
1616.
L. M. D. R. S. Martins and A. J. L. Pombeiro, Inorg. Chem.,
2008, 47, 10158–10168.
35 F. Tisato, L. Crociani, M. Porchia, P. Di Bernardo,
F. Endrizzi, C. Santini and R. Seraglia, Rapid Commun. 55 W. Kläui, M. Berghahn, G. Rheinwald and H. Lang, Angew.
Mass Spectrom., 2013, 27, 2019–2027. Chem., Int. Ed., 2000, 39, 2464–2466.
36 U. Siegert, H. Hahn and H. Lang, Inorg. Chim. Acta, 2010, 56 Bruker, APEX2, Bruker AXS Inc., Madison, Wisconsin, USA,
363, 944–948. 2012.
37 A. Lis, M. F. C. Guedes Da Silva, A. M. Kirillov, 57 G. M. Sheldrick, SADABS. Program for Empirical Absorption
P. Smoleński and A. J. L. Pombeiro, Cryst. Growth Des.,
2010, 10, 5244–5253.
38 C. Pettinari, F. Marchetti, G. Lupidi, L. Quassinti,
M. Bramucci, D. Petrelli, L. A. Vitali, M. F. C. Guedes Da
Correction, University of Gottingen, Germany, 2000.
58 A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano,
C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori
and R. Spagna, J. Appl. Crystallogr., 1999, 32, 115–119.
Silva, L. M. D. R. S. Martins, P. Smoleński and 59 G. M. Sheldrick and IUCr, Acta Crystallogr., Sect. A: Found.
A. J. L. Pombeiro, Inorg. Chem., 2011, 50, 11173–11183. Crystallogr., 2008, 64, 112–122.
39 J. Almeida, C. Roma-Rodrigues, A. G. Mahmoud, 60 L. J. Farrugia, J. Appl. Crystallogr., 2012, 45, 849–854.
M. F. C. Guedes da Silva, A. J. L. Pombeiro, 61 K. R. Reddy, K. Rajgopal and M. L. Kantam, Synlett, 2006,
L. M. D. R. S. Martins, P. V. Baptista and A. R. Fernandes,
J. Inorg. Biochem., 2019, 199, 110789.
40 A. G. Mahmoud, L. M. D. R. S. Martins, M. F. C. Guedes da
Silva and A. J. L. Pombeiro, Catalysts, 2019, 9, 611.
957–959.
62 K. Lőrincz, P. Kele and Z. Novák, Synthesis, 2009, 3527–
3532.
63 Z. Gonda and Z. Novák, Dalton Trans., 2010, 39, 726–729.
41 J. García-Álvarez, J. Díez, J. Gimeno, F. J. Suárez and 64 W. Wang, J. Wu, C. Xia and F. Li, Green Chem., 2011, 13,
C. Vincent, Eur. J. Inorg. Chem., 2012, 2012, 5854–5863. 3440–3445.
42 S. Lal and S. Díez-González, J. Org. Chem., 2011, 76, 65 I. S. Park, M. S. Kwon, Y. Kim, J. S. Lee and J. Park, Org.
2367–2373.
Lett., 2008, 10, 497–500.
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 6109–6125 | 6125