2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine as ligands in copper(II) and nickel(II) complexes

Article abstract of DOI:10.1515/znb-2016-0026

2-(1-Benzyl-1H-1,2,3-triazol-4-yl)-imidazolines (L1 and L2/L2′), -1,3-oxazoline (L3), -1,3-thiazoline (L4) and -tetrahydropyrimidine (L5) were prepared in one step from a 1,2,3-triazole-4-carboxamidinium tetraphenylborate and studied as novel ligands for copper(II) and nickel(II) ions. The solid-state structures of the following complexes were established: [Cu(L1)₂](OTf)₂, [CuL2L2′(OTf)₂] · 2H₂O, [[Cu(L4)₂(H₂O)₂](OTf)₂ · [Cu(L4)₂(OTf)₂], [Cu(L5)₂(OTf)₂], Cu(L3)₂Cl₂] · THF, [Ni(L1)₂Cl₂].

Full text of DOI:10.1515/znb-2016-0026

Z. Naturforsch. 2016; aop
Sven Schröder, Wolfgang Frey and Gerhard Maas*
2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline,
-thiazoline and -tetrahydropyrimidine as ligands
in copper(II) and nickel(II) complexes
DOI 10.1515/znb-2016-0026
light-emitting materials, sensitizers in dye-sensitized solar
cells, radiolabeled pharmaceuticals and building blocks
for discrete or polymeric supramolecular architectures
(for reviews and selected examples, see Refs. [1, 7–12]).
Another interesting development is found in the field of
organometallic complexes with triazole-derived ligands,
in particular complexes of various transition metals with
1,3,4- or 1,2,4-trisubstituted 1,2,3-triazol-5-ylidene ligands,
which have recently been shown to catalyze effectively
several important organic transformations as well as pho-
tocatalytic water oxidation [13].
Received February 1, 2016; accepted February 9, 2016
Abstract:
2-(1-Benzyl-1H-1,2,3-triazol-4-yl)-imidazolines
(L1and L2/L2′), -1,3-oxazoline (L3), -1,3-thiazoline (L4) and
-tetrahydropyrimidine (L5) were prepared in one step from
a 1,2,3-triazole-4-carboxamidinium tetraphenylborate and
studied as novel ligands for copper(II) and nickel(II) ions.
The solid-state structures of the following complexes
were established: [Cu(L1)2](OTf)2, [CuL2L2′(OTf)2] · 2H2O,
[[Cu(L4)2(H2O)2](OTf)2 · [Cu(L4)2(OTf)2], [Cu(L5)2(OTf)2],
Cu(L3)2Cl2] · THF, [Ni(L1)2Cl2].
∧
Complexes with bidentate N N chelating ligands
Keywords: amidinium salt; bidentate ligands; copper com- incorporating a 1,2,3-triazole moiety have also been found
plexes; copper(II) triflate; nickel complex; 1,2,3-triazoles.
to be catalytically active. Thus, several palladium com-
plexes with (2-pyridyl)-1,2,3-triazole ligands (1, Fig. 1) were
found to catalyze effectively some modern C,C coupling
reactions, namely Suzuki–Miyaura, Sonogashira and Heck
reactions [14]. Some triazole-containing compounds are
useful rate-enhancing co-ligands for the CuAAC reaction
[15]. For example, copper complexes formed from CuCl2
and triazole ligands of the type 2 exhibited good to very
good performance in catalyzing this reaction [16]. An octa-
hedral NiBr2 complex with a tetradentate 1,2,3-triazole/
acenaphthene quinone diimine ligand was found to be an
efficient precatalyst for the MAO induced polymerization
of styrene [17].
In a way, the atom connectivity in the first coordina-
tion sphere of bidentate ligands 1 is reminiscent of that
in bis(1,3-oxazolines) 3, which in their enantiomerically
pure chiral version have contributed to impressive enan-
tioselectivities in several copper-catalyzed asymmetric
transformations, as shown in the pioneering studies by
the groups of Pfaltz [18], Masamune [19, 20] and Evans
[21, 22]. Being interested in novel triazole-derived chelat-
ing ligands and their copper complexes, we aimed at
conjugates of the ring systems of 1,2,3-triazole and cyclic
amidines (i.e. imidazoline and tetrahydropyrimidine),
1,3-oxazoline and 1,3-thiazoline. Results of these studies
are reported herein. Notably, heterocyclic conjugates of
this type are almost unknown. A synthetic access, dif-
ferent from ours [23], to the triazole-oxazoline scaffold
L3 (see Scheme 1) has been published [23]. Also, several
1 Introduction
The ability of aromatic five-membered heterocycles with
three or four nitrogen atoms – 1,2,3-triazoles, 1,2,4-tria-
zoles and tetrazoles – to act as ligands in coordination
chemistry has been known for a long time. The rather
simple synthetic access to these ring systems, enabling
also the preparation of a broad range of substituted
derivatives, has meanwhile led to a considerable collec-
tion of triazole- [1, 2] and tetrazole-containing [1, 3–5]
ligands for metal complexation with diverse coordination
motifs. As far as 1,2,3-triazoles are concerned, the recent
advent of the copper(I)-catalyzed version of the azide–
alkyne [3+2] cycloaddition (CuAAC), due to its operative
simplicity, mild reaction conditions and regioselectivity
[6], has spurred the interest in 1,2,3-triazole containing
ligands and their use for diverse functional metal coor-
dination compounds such as spin-crossover complexes,
*Corresponding author: Gerhard Maas, Institute of Organic
Chemistry I, University of Ulm, 89081 Ulm, Germany,
Fax: +49 (0)731 5022803, E-mail: gerhard.maas@uni-ulm.de
Sven Schröder: Institute of Organic Chemistry I, University of Ulm,
89081 Ulm, Germany
Wolfgang Frey: Institute of Organic Chemistry, University of
Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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ꢀꢀꢀꢁ
2ꢀ ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
R
Ph
R1
R1
Dynamic prototropic equilibria are present in the
X
N
O
O
cases of cyclic amidine ligands L1, L2 and L5, as indicated
Ar
N
N
N
1
by broadening of the H and/or 13C NMR signals of the
N
N
N
N
N
R = H, CH2Ph
Ar = 4-ClC6H4
NCH2 (and NCH) nuclei. Only in the case of L2, however,
does proton tautomerism lead to structurally different
tautomers (L2 and L2′), which are both incorporated in a
complex with Cu(OTf)2 (vide infra).
R2
R2
X = CH2O, O, N(Me), S
3
1
2
Fig. 1:ꢀExamples of bidentate ligands for catalytically active
complexes.
(1,2,3-triazol-1-yl)-(1,3-oxazol-2-yl and 1,3-thiazol-2-yl) 2.2 Complex formation with copper(II)
methane derivatives have been synthesized very recently
triflate
[25]. In both cases, however, no complex formation studies
were performed.
Copper(II) trifluoromethanesulfonate (triflate) is suffi-
ciently soluble in several common aprotic-polar organic
solvents, so that complexation with organic ligands can
take place in a homogeneous medium. Water, which
could also act as a ligand, can be excluded a priori. Nev-
ertheless, adventitious water in some cases was incor-
porated into the complex itself or in the crystal lattice
during crystallization attempts or exposure to air of the
2 Results and discussion
2.1 Syntheses
In a preceding paper, we have reported the preparation first formed solid complex. Figure 2 shows the structures
of the 1,2,3-triazole-carboxamidinium tetraphenylborate of the Cu(OTf)2 derived complexes, the solid-state struc-
1 and its one-step conversion into the 2-(1,2,3-triazol- tures of which could be established by single-crystal X-ray
4-yl)imidazoline L1 [24]. In an analogous manner, we structure determination. In all complexes derived from
have now combined salt 1 with enantiomerically pure Cu(OTf)2, the organic ligands act as bidentate chelating
(R)-propane-1,2-diamine to provide the chiral triazole/ ones, coordinating to the copper(II) ion at the 1H-triazole
imidazoline hybride ligand L2 (Scheme 1). The conden- ring position N-3 and at the imine nitrogen atom of the
sation of salt 1 with 2-aminoethanol, 2-aminoethanethiol cyclic amidine or a related ring system. On the other hand,
and propane-1,3-diamine provided the corresponding tri- the coordination of the triflate anion, which is known as
azolyl-substituted 1,3-oxazoline L3, 1,3-thiazoline L4 and being a weakly coordinating ion in metal triflates and tri-
tetrahydropyrimidine L5, all of which were formed in high flato complexes [26], is subject to variations depending on
yield (Scheme 1).
the particular complex.
H
H
N
Ph
N
Ph
N
N
N
N
N
N
N
N
Me
Me2N
a
L2
L1
N+Me2
–BPh4
b
Ph
N
N
N
N
Ph
Ph
N
N
1
N
N
N
H
c
Me
e
L2′
d
HN
S
N
O
Ph
Ph
N
N
N
N
N
N
N
N
N
N
L3
L4
L5
Scheme 1:ꢀSynthesis of ligands L1–L5. Conditions and yields: (a) H2N(CH2)2NH2, anhydrous K3PO4, CH3CN, rfx, 5 h, 92% [24]; (b) (R)-propane-
1,2-diamine, anhydrous K3PO4, CH3CN, rfx, 12 h, 92%; (c) HO(CH2)2NH2, anhydrous K3PO4, CH3CN, rfx, 18 h, 88%; (d) HS(CH2)2NH2, anhydrous
K3PO4, CH3CN, rfx, 24 h, 88%; (e) H2N(CH2)3NH2, anhydrous K3PO4, CH3CN, rfx, 18 h, 91%.
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ꢁꢀꢀꢀ
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ
ꢂ3
Ph
Ph
N
Ph
N
Ph
Ph
N
CH3
N
N
N
N
N
N
N
OTf
Cu
OTf
Cu
OH
Cu
OTf
Cu
2 N
N
S
N
S
N
N
N
N
N
N
NH
N
N
N
N
N
N
N
H
H
OTf
H
Cu
OTf
H
HN
N
N
N
N
N
N
S
N
S
N
OTf
OTf
OH2
OTf
N
N
N
N
N
N
N
N
N
N
2 TfO–
CH3
Ph
Ph
Ph
Ph
[Cu(L4)2(H2O)2](OTf)2
Fig. 2:ꢀCu(OTf)2 derived complexes that were structurally characterized in this study (OTf ꢃ=ꢃ O3SCF3).
Ph
[Cu(L1)2](OTf)2
[CuL2L2′(OTf)2]
[Cu(L4)2(OTf)2]
[Cu(L5)2(OTf)2]
By concentration of an ethyl acetate solution of crystallographic inversion symmetry; four nitrogen atoms
Cu(OTf)2 and ligand L1, light brown crystals were obtained, (two of each ligand) surround the copper ion in a dis-
the X-ray structure determination of which established the torted square-planar geometry (Table 1). The two triflate
composition [Cu(L1)2](OTf)2 (Fig. 3). This complex exhibits anions, which are both slightly disordered by rotation
Fig. 3:ꢀMolecular structure of complex [Cu(L1)2](OTf)2 in the solid state (Ortep plot).
Table 1:ꢀSelected bond lengths (Å) and angles (deg) in Cu(OTf)2 derived complexes.
[Cu(L1)2](OTf)2
ꢁ
[CuL2L2′(OTf)2]ꢁ×ꢁ2H2O
ꢁ
[Cu(L5)2](OTf)2
ꢁ
[Cu(L4)2(H2O)2](OTf)2
ꢁ
[Cu(L4)2OTf)2]
Cu–N3triaz 2.028(1)
Cu–N3′triaz 2.028(1)
Cu–N4imid 1.934(1)
Cu–N4′imid 1.934(1)
C3–N4imid 1.306(2)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Cu1–N1triaz 2.014(4)
Cu1–N6triaz 2.015(4)
Cu1–N4imid 1.951(4)
Cu1–N9imid 1.967(4)
C3–N4imid 1.308(6)
C17–N9imid 1.285(6)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Cu–N1triaz 2.041(2)
Cu–N6triaz 2.030(2)
Cu–N4pyrim 1.977(3)
Cu–N9pyrim 1.982(3)
C16–N9pyrim 1.297(4)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Cu1–N2triaz 2.038(2)
Cu1–N2′triaz 2.038(2)
Cu1–N1thiaz 1.991(2)
Cu1–N1′thiaz 1.991(2)
C3–N1thiaz 1.275(4)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Cu2–N7triaz 1.988(3)
Cu2–N7′triaz 1.988(3)
Cu2–N5thiaz 2.004(2)
Cu2–N5′thiaz 2.004(2)
C15–N5thiaz 1.283(4)
N3–Cu–N3′ 180.00(5)ꢃ
N3–Cu–N4 81.89(5)
N3–Cu–N4′ 98.11(5) ꢃ
N4–Cu–N4′ 180.00(5)ꢃ
C3–N4–Cu 115.5(1)
C1–N3–Cu 111.6(1)
N1–Cu1–N6 177.70(16) ꢃ
N1–Cu–N6 179.12(10)ꢃ
N1–Cu–N4 81.30(10) ꢃ
N1–Cu–N9 98.66(10) ꢃ
N6–Cu–N9 81.08(10) ꢃ
N2–Cu1–N2′ 180.00(14)ꢃ
N2–Cu1–N1 81.22(10) ꢃ
N2–Cu1–N1′ 98.78(10) ꢃ
N1–Cu1–N1′ 180.00(18)ꢃ
N7–Cu2–N7′ 180.00(10)
N7–Cu2–N5 81.16(10)
N7–Cu2–N5′ 98.84(10)
N5–Cu2–N5′ 180.00(10)
C15–N5–Cu2 114.3(2)
C16–N7–Cu2 113.3(2)
Cu2···O4 2.441(2)
ꢃ
N1–Cu1–N4 81.27(17)
N1–Cu1–N9 99.37(15)
N6–Cu1–N9 81.19(17)
C3–N4–Cu1 116.3(3)
C2–N1–Cu1 112.7(3)
Cu1···O1 2.602(3)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C3–N4–Cu 115.9(2)
C2–N1–Cu 110.8(2)
Cu···O1 2.689(2)
Cu···O6 2.535(2)
ꢃ
ꢃ
ꢃ
ꢃ
C3–N1–Cu1 115.1(2)
C4–N2–Cu1 111.0(2)
Cu1···O1 2.371(3)
Cu1···O1′ 2.371(3)
ꢃ
ꢃ
ꢃ
ꢃ
Cu1···O4 2.620(3)
O1···Cu1···O4 177.59(4) ꢃ
Cu2···O4′ 2.441(2)
O4···Cu2···O4′ 180.0(2)
O1···Cu···O6 163.12(8)ꢃ
O1···Cu1···O1′ 180.0(2) ꢃ
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ꢀꢀꢀꢁ
4ꢀ ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
around the C–S bond, are not associated with the metal, surprisingly, however, an X-ray structure determination
but are engaged in an O···H–N hydrogen bond to the imi- revealed the composition [CuL2L2′(OTf)2] · 2H2O, i.e. a
dazoline ring of both organic ligands (d(O···N) ꢀ=ꢀ 2.83(3)– complex molecule containing both imidazoline tautom-
2.86(3) Å). Additionally, weak interactions of the O···H–C ers, (R)-L2 and (R)-L2′ (Fig. 4, top). The copper(II) ion is
type between a triflate oxygen atom and CHtriazole (d(O···H) surrounded by four nitrogen atoms in a distorted square-
~2.35 Å) and m-CHphenyl (~2.42 Å) may be present.
planar geometry which is extended into a tetragonally dis-
The blue crystals obtained from Cu(OTf)2 and ligand torted octahedral arrangement by two weakly coordinated
(R)-L2/(R)-L2′ by crystallization from ethyl acetate-die- triflate anions (Cu1···O1 2.602(3), Cu1···O4 2.620(3) Å)).
thyl ether showed the expected 1:2 metal-to-ligand ratio; Notably, the triflate anions do not maintain O···H–N
Fig. 4:ꢀTop: molecular structure of complex [CuL2L2′(OTf)2] · 2 H2O in the solid state (Ortep plot). Bottom: water molecules involved in
O–H···O hydrogen bonds; for clarity, Nimidazoline–H···O bonds involving the water molecules are not shown (Mercury plot). Geometrical data
(d(D···A), angle D–H···A; D ꢃ=ꢃ donor, A ꢃ=ꢃ acceptor) for N5–H···O8: 2.811(7) Å, 157°; for N10–H···O7: 2.768(8) Å, 157°; for O7–HA···O1: 2.841(7)
Å, 155°; for O7–HB···O6 2.756(7) Å, 163°; for O8–HA···O3: 2.834(8) Å, 150°; for O8–HB···O4: 2.872(7) Å, 169°.
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ꢁꢀꢀꢀ
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ ꢂ5
hydrogen bonds with the imidazoline rings of neighboring two copper–oxygen distances are rather long again, and
ligands. Rather, two water molecules, which are present additionally, they differ more from each other and the
in the asymmetric unit of the crystal, connect two triflate O···Cu···O angle is farther away from linearity. Besides
ions via O···H–O bonds (Fig. 4, bottom) and each of them using one oxygen atom for coordination to the copper
is associated with an imidazoline ring via an O···H–N atom, each triflate group is engaged with a second oxygen
hydrogen bond.
Blue crystals of a complex formed from Cu(OTf)2 and group of another complex molecule (Fig. 5, bottom).
triazolyl-tetrahydropyrimidine L5 were obtained by slow
When a solution of Cu(OTf)2 and ligand L4 in ethyl
atom in an O···H–N hydrogen bond to the amidine NH
diffusion of diethyl ether into an n-butanol solution of acetate was slowly concentrated by solvent evaporation
the components; crystallization attempts from other with exposure to air, light blue crystals were formed,
solvents or solvent mixtures were unsuccessful. Accord- which analyzed for the composition Cu(L4)2(OTf)2(H2O)
ing to an X-ray analysis, the complex [Cu(L5)2(OTf)2] had but according to an X-ray analysis were in fact 1:1 cocrys-
been formed (Fig. 5, top). Similar to the complex with tals of two different complexes, namely a diaqua and a
the triazolyl-imidazoline ligand L2/L2′, a distorted octa- bis(triflato) copper(II) complex, [Cu(L4)2(H2O)2](OTf)2 ·
hedral coordination geometry with the two triflate ions [Cu(L4)2(OTf)2] (Fig. 6). Both complex entities are cen-
occupying the apical positions is observed (Table 1). The trosymmetrical with the copper ion on a crystallographic
Fig. 5:ꢀTop: molecular structure of complex [Cu(L5)2(OTf)2] in the solid state (Ortep plot). Bottom: N–H···O hydrogen bonding in the crystal
structure (Mercury plot). Geometrical data (d(N–H), d(H···O), d(N···O), angle N–H···O) for N5–H5···O5: 0.83, 2.08, 2.895(3), 164(3)°; for
N10–H10···O2: 0.83, 2.03, 2.821(4), 159(4)°.
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ꢀꢀꢀꢁ
6ꢀ ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
Fig. 6:ꢀMolecular structure and packing of complex [Cu(L4)2(H2O)2](OTf)2/[Cu(L4)2(OTf)2] in the solid state (Ortep plot). Geometrical data
(d(D–H), d(H···A), d(D···A), angle D–H···A; D ꢃ=ꢃ donor, A ꢃ=ꢃ acceptor) for O1–HA···O2: 0.82(4), 2.06(4), 2.826(4), 155(4)°; for O1–HB···O7:
0.86(5), 1.90(5), 2.742(4), 168(4)°.
inversion center. The coordination geometries can be are found in the range 1531–1573 cm−1 for the free ligands,
described as distorted octahedral with the oxygen ligands but at higher wavenumbers (by 12–40 cm−1) in the com-
in the apical positions. The Cu···O distances amount to plexes, except for Cu(L3)2Cl2, where the triazole part
2.371(3) Å in the diaqua complex and 2.441(2) Å in the remains uncoordinated (vide infra). Of particular inter-
bis(triflato) complex. Although the triflate coordination est is the region between 1300 and 1000 cm−1, where
may be rather weak, the contact distance is the short- strong absorptions associated with stretching modes of
est one among the triflato complexes presented here. In the CF3SO3 group dominate. In the past, the assignment
notable contrast to all other complexes, the Cu–Ntriazole and of the vibration modes of the triflate group has found
Cu–Nthiazole distances are almost equal in [Cu(L4)2OTf)2], much attention, mainly in order to distinguish between
and moreover, the Cu–Ntriazole bonds are even slightly a free and a coordinated triflate ion. When a triflate ion
longer. The two complex entities in the crystals are con- becomes mono- or di-coordinated – either to a metal
nected through hydrogen bonds between the water atom or by a strong hydrogen bond – the C3v symme-
ligands of the diaqua complex and a triflate oxygen atom try of the free triflate ion is reduced to Cs, resulting in
of the bis(triflato) complex. The two triflate anions, which a splitting of the E type vibrations. Thus, the asymmet-
compensate the positive charge of the diaqua complex, ric stretching vibration of the SO3 group, which appears
are each involved in one hydrogen bond with a water around 1270 cm−1 for the uncoordinated triflate [27], is
ligand but remain uncoordinated otherwise.
expected to be split. This splitting was observed indeed
In the IR spectra of the complexes, absorption bands in a number of triflate-containing copper complexes, the
in the 1540–1650 cm−1 region, attributable to vibrations solid-state structures of which have been determined.
in the triazole and the second heterocyclic ring, are sig- Following the established assignment of the relevant
nificantly displaced compared to the free ligands. In vibration modes of the triflate ion (for examples, see lit.
detail, the Cꢀ=ꢀN stretching vibrations of the imidazoline, [27–32]), the assignments shown in Table 2 were made for
oxazoline, thiazoline and tetrahydropyrimidine rings the Cu(OTf)2 complexes under study. It can be seen, that
appear between 1625 and 1640 cm−1 in the free ligands splitting of the νas(SO3) vibration is observed in all cases,
and are shifted to higher wavenumbers in the complexes including complex [Cu(L1)2](OTf)2, where the triflate ions
containing the cyclic amidine ligands and to lower ones are involved in N–H···O hydrogen bonding according
in the oxazoline and thiazoline complexes. Absorption to the crystal structure analysis, but not in metal coor-
bands of the N-benzyl-1,2,3-triazole part of the ligands dination. As we have indicated in Table 2, some of the
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ꢁꢀꢀꢀ
ꢂ7
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ
Table 2:ꢀIR vibrations associated with the CF3SO3 ion in the copper(II) triflate complexes under study (wavenumbers, cm−1).a,b
Vibration
ꢁ
Cu(L1)2](OTf)2ꢁ
[CuL2L2′(OTf)2]ꢁ
[Cu(L5)2](OTf)2ꢁ
[Cu(L4)2(H2O)2](OTf)2 [Cu(L4)2OTf)2]
νas(SO3)
νs(CF3)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
1296/1253ꢃ
1228*ꢃ
1148ꢃ
1029ꢃ
757ꢃ
1285/1243ꢃ
1284/1256ꢃ
1225*ꢃ
1167ꢃ
1032ꢃ
759ꢃ
1286/1246
1224*
~1225–1230 shꢃ
νas(CF3)
1159ꢃ
1028ꢃ
ꢃ
636ꢃ
574ꢃ
518ꢃ
1158
νs(SO3)
1028
δs(CF3) + νs(CS)c
δs(SO3)
629ꢃ
637ꢃ
639
576*
518
δas(CF3)
δas(SO3)
575ꢃ
520ꢃ
576ꢃ
518ꢃ
aSpectra were recorded from KBr pellets; babsorptions marked with an asterisk appear at the same wavenumber as an absorption of the free
ligand; cthe δs(CF3) absorption, which should appear around 752 cm−1 [27] and has been described as “weak” or “medium” in the literature,
could not be identified with certainty. Only in two cases, weak absorptions were observed at approximately this wavenumber.
absorption bands arising from the triflate ions appear at
more or less the same wavenumber as absorptions also
2.3 Complexes with CuCl2 and NiCl2
observed for the free ligand, but due to the high inten- Similar to Cu(OTf)2, CuCl2 is also soluble in a variety
sity of the triflate absorption bands, the assignment is of aprotic-polar organic solvents and in the lower ali-
unequivocal.
phatic alcohols. The complexation of solvatochromic
Electronic spectra of some of the Cu(OTf)2 complexes CuCl2 by ligand L1 in several solvents was indicated
were recorded. For solubility reasons, acetonitrile had by a characteristic color change to dark green, but the
to be used as the solvent; since no visible color change very thin needle-shaped crystals or amorphous solids
was noted between the complexes in the solid state and obtained were not suited for single-crystal X-ray struc-
in solution, we can assume that acetonitrile molecules ture determination.
did not replace the triflate ions as ligands. The spectra
With the triazole/oxazoline ligand L3, on the other
display two absorption maxima above 350 nm, which are hand, copper(II) chloride in tetrahydrofuran formed crys-
not present in the spectra of the free ligands: one around tals of the dark blue complex [Cu(L3)2Cl2] · THF. In the
370–380 nm, belonging to a broadened absorption that crystal structure, copper resides on an inversion center
extends into the visible region and in some cases includes and has a square-planar coordination with the symme-
a shoulder at the longer wavelength side, and the other try-related ligands in trans position (Figs. 7 and 8). The
one as a very broad, low-intensity absorption in the visible organic ligands coordinate solely at the imine nitrogen
region with maxima in the range of 608–664 nm (Table 3). atom of the oxazoline ring, but not at the less nucleo-
The latter absorption band is unsymmetrical, with a long philic N1 position of the triazole ring. The structure of
tailing up to about 950 nm. Absorptions in this range are the complex is analogous to that of Cu(1-ethyltetrazole-
commonly assigned to ligand-field transitions within N4)2Br2] [34] and also to the complex comprising CuCl2 and
tetragonally distorted octahedral Cu(II) complexes. [28, ligand 2 (Fig. 1, X ꢀ=ꢀ CH2O), [Cu(2)Cl2], where geometrical
33]. The absorption at higher energy is likely to arise from constraints obviously do not allow the oxygen atom in
a π(ligand)-d(Cu(II)) charge transfer transition [28].
the side chain to coordinate to the metal atom [16]. On
the other hand, ligand 3 (Fig. 1, R1 ꢀ=ꢀ Me, R2 ꢀ=ꢀ tert-Bu) and
CuCl2 form a 1:1 chelate complex with a distorted tetrahe-
dral geometry around the copper atom [35]. Notably, the
long-wavelength absorption of our CuCl2/bis(oxazoline)
complex appears at λ ꢀ=ꢀ 748 nm, i.e. with a large bato-
Table 3:ꢀElectronic absorption bands of some complexes in acetoni-
trile solution.
Complex
ꢁ
λmax (ε in L mol−1 cm−1) chromic shift compared to the complexes derived from
Cu(OTf)2 (Table 2).
[Cu(L1)2](OTf)2
[CuL2L2′(OTf)2]
ꢃ
ꢃ
368 (239), ~415 (sh, 171), 643 (72)
371 (259), 656 (64)
The formation of nickel complexes was thwarted
[[Cu(L4)2(H2O)2](OTf)2 ·ꢃ
[Cu(L4)2OTf)2]
364 (245), 664 (70) by the insufficient solubility of simple nickel salts in
common organic solvents. However, crystals of the light
[Cu(L5)2](OTf)2
[Cu(L3)2]Cl2
ꢃ
ꢃ
370 (sh, 168), 608 (87)
375 (264), ~420 (sh, 225), 748 (118)
green complex [Ni(L1)2Cl2] could be obtained in modest
yield from nickel(II) chloride and L1 in n-propanol. The
Unauthenticated
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ꢀꢀꢀꢁ
8ꢀ
ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
O
and 9). The complex has crystallographic C2 symmetry;
NH
Ph
N
Ph
the twofold rotation axis bisects the Cl–Ni–Cl′ angle. As
in most of the copper complexes, the Ni–N(imine) dis-
tance is distinctly shorter than the Ni–N(triazole) dis-
tance (2.046 vs. 2.172 Å). The crystal packing is stabilized
by N–H···Cl hydrogen bonds which connect each chlorine
atom of a complex molecule with the imidazoline rings of
another molecule.
N
N
N
Cl Cu Cl
N
N
N
N
N
N
Cl
Cl
Ni
N
N
N
N
N
N
Ph
O
Ph
NH
[Ni(L1)2Cl2]
[Cu(L3)2Cl2]
Fig. 7:ꢀStructural formulae of complexes derived from CuCl2 and NiCl2.
3 Conclusion
X-ray structure determination revealed a distorted octa-
hedral coordination geometry with the planes of the two In this study, we have used amidinium chemistry for the
ligands L1 being perpendicular to each other (Figs. 7 synthesis of 2-(1,2,3-triazol-4-yl)-imidazoline, -oxazoline,
Fig. 8:ꢀMolecular structure of complex [Cu(L3)2Cl2] · THF in the solid state (Ortep plot). The positionally disordered tetrahydrofuran mol-
ecule is not shown. Selected bond lengths and angles: Cu–N4 ꢃ=ꢃ Cu–N4′ 1.957(2), Cu–Cl ꢃ=ꢃ Cu–Cl′ 2.2957(6), C3–N4 1.277(3) Å; N4–Cu–N4′
180.00(4), Cl–Cu–Cl′ 180.00(3), N4–Cu–Cl 89.40(5), N4′–Cu–Cl 90.60(5), C3–N4–Cu 128.51(15)°.
Fig. 9:ꢀLeft: molecular structure of complex [Ni(L1)2Cl2] in the solid state (Ortep plot). Selected bond lengths and angles: Ni–N1 ꢃ=ꢃ Ni–N1′
2.1723(14), Ni–N4 ꢃ=ꢃ Ni–N4′ 2.0460(13), Ni–Cl ꢃ=ꢃ Ni–Cl′ 2.4186(5), C3–N4 1.294(2) Å; N1–Ni–N1′ 88.03(7), N1–Ni–Cl 88.51(4), N1–Ni–Cl′
168.82(4), Cl–Ni–Cl′ 96.78(2), N1–Ni–N4 95.71(5), N4–Ni–N4′ 171.63(8), Ni–N1–C2 110.92(10), Ni–N4–C3 116.57(11)°. Right: Details of the
crystal structure, featuring N–H···Cl hydrogen bonds (Mercury plot). Data for N5–H5N···Cl (x–0.5, y–0.5, –z+1.5): d(N–H) 0.88(3) Å, d(H···Cl)
2.33(3) Å, d(N···Cl) 3.195(2) Å, (N–H···Cl) 167(2)°.
Unauthenticated
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ꢁꢀꢀꢀ
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ ꢂ9
-thiazoline and -tetrahydropyrimidine hybrids. These internal standard: δ(CHCl3) ꢀ=ꢀ 7.26 ppm, δ(CDCl3) ꢀ=ꢀ 77.0
compounds represent novel bi-heterocyclic ligands for ppm; CD3OD: 3.31 and 49.0 ppm; [D6]DMSO: 2.50 and 39.5
metal complexation, as shown here for Cu(II) and Ni(II) ppm; CD3CN: 1.94 and 1.30 ppm. – IR spectra: Bruker
complexes. With σ donation by a triazole nitrogen atom Vector 22; wavenumbers (cm−1) and intensities (vs ꢀ=ꢀ very
and the imine-type nitrogen atom of the other heterocy- strong, s ꢀ=ꢀ strong, m ꢀ=ꢀ medium, w ꢀ=ꢀ weak, br ꢀ=ꢀ broad)
clic ring, these ligands in principle can act as bidentate are given, spectra were recorded from KBr pellets. – Mass
chelating ones. This was observed indeed for all structur- spectra: MALDI-TOF spectra were recorded with a Bruker
ally characterized copper(II) triflate complexes as well as Daltonics REFLEX III instrument, trans-2-(3-(4-tert-
for the octahedral complex [Ni(L1)2Cl2]. Only in the CuCl2– butylphenyl)-2-methyl-2-propenylidene)malononitrile
bis(oxazoline) complex trans-[Cu(L3)Cl2], the organic (DCTB) was used as matrix. Elemental analyses: elemen-
ligand is monodentate and coordinates at the imine-type tar vario MICRO cube and elementar Vario EL; values
nitrogen atom only.
are given in percent. Melting points were determined on
The triflate ion is known as a weakly coordinating a Büchi Melting Point B-540 apparatus. Solvents were
anion. This is confirmed in the solid-state structures of distilled, dried by standard methods and stored under
the Cu(OTf)2 derived complexes studied here. If hydrogen argon. Column chromatography was performed on silica
bond donors (OH of water molecules and NH of amidine gel 60 (Macherey–Nagel, 0.063–0.2 mm) or basic acti-
ligands) are present, they compete or cooperate with the vated alumina 90 (Merck).
O···Cu coordination. Consequently, we observed the com-
plete absence of triflate-to-metal coordination in the dis-
torted square-planar complex [Cu(L1)2](OTf)2. In the other 4.2 Syntheses of ligands L1–L5
complexes a distorted square-pyramidal coordination
around copper with two triflate ions in the apical posi- 1-Benzyl-N,N,N′,N′-tetramethyl-1,2,3-triazole-4-carboxa-
tions and rather long Cu···O contacts (2.441–2.689 Å), i.e. midinium tetraphenylborate (1) and 1-benzyl-4-(4,5-dihy-
values much above the sum of the covalence radii (2.20 dro-1H-imidazol-2-yl)-1H-1,2,3-triazole (L1) were prepared
Å), was found.
While this study has had a focus on structural aspects
according to the published procedures [24].
of copper(II) and nickel(II) complexes with novel 1,2,3-tri-
azole containing biheterocyclic ligands, for which cata-
lytic applications can be foreseen, it should be kept in
mind that 1,2,3-triazole moieties can also be incorporated
in potentially bioactive compounds [36, 37]. Insofar, the
triazole-imidazoline, -oxazoline and -thiazoline scaffolds
presented here could also serve as model compounds for
the study of biologically relevant metal ion (Cu(II), Zn(II))/
ligand interactions. Along these lines, triazolyl-oxazoline
L3, assuming that it would act as a bidentate chelating
ligand for Zn(II), has already been tested as an inhibi-
tor of several metalloproteinases, but showed no such
activity [23].
4.2.1 (R)-1-Benzyl-4-(4-methyl-4,5-dihydro-1H-imidazol-
2-yl)-1H-1,2,3-triazole (L2) and (R)-1-benzyl-4-
(5-methyl-4,5-dihydro-1H-imidazol-2-yl)-1H-1,2,3-
triazole (L2′)
To a solution of amidinium salt 1 (288 mg, 0.50 mmol)
and (R)-1,2-diaminopropane dihydrochloride (88 mg,
0.60 mmol) in dry acetonitrile was added anhydrous K3PO4
(106 mg, 0.50 mmol) and the mixture was heated at reflux
for 12 h. After cooling the solvent was evaporated, and a
solution of the residue in ethyl acetate-ethanol (9:1 v/v)
was filtered over a column filled with alumina (10 g). The
productwasisolatedasacolorlesssolid(110mg,0.46mmol;
ꢀ
yield: 92%). M.p. 167.5–169°C. – IR (KBr): ν = 3244 m, 3105
m, 2957 w, 2919 w, 1626 s, 1561 s, 1452 m, 1285 m, 1232 m,
1050 m, 711 m cm−1. – 1H NMR (CDCl3): δ ꢀ=ꢀ 1.28 (d, 3J ꢀ=ꢀ 6.4
Hz, 3 H, CH3), 3.34 (dd, J ꢀ=ꢀ 11.4, 7.8 Hz, 1 H, NCHA), 3.88
(dd, J ꢀ=ꢀ 11.4, 9.8 Hz, 1 H, NCHB), 4.09–4.18 (centered m, 1 H,
NCHCH3), 5.03 (very broad, 1 H, NH), 5.54 (s, 2 H, PhCH2),
4 Experimental section
4.1 General information
13
1H and C NMR spectra were recorded on a Bruker DRX 7.26–7.28 (m, 2 H, HPh), 7.35–7.37 (m, 3 H, HPh), 8.08 (s, 1 H,
400 spectrometer (1H: 400.13 MHz; 13C: 100.61 MHz); 5-Htriaz) ppm. – 13C NMR ([D4]methanol): δ ꢀ=ꢀ 21.7 (CH3), 54.6
δ values are reported in ppm and coupling constants (PhCH2), 56.8 (coalescing, NCH2/NCH), 124.3 (C-5triaz); 128.5,
in Hertz (Hz). The signal of the solvent was used as an 129.2, 129.4, 133.8 (alle CPh); 139.7 (C-4triaz), 156.4 (NCꢀ=ꢀN)
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ꢀꢀꢀꢁ
10ꢀ ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
ppm. – Anal. for C13H15N5 (241.13): calcd. C 64.71, H 6.27, N 159.6 (C-2thiaz) ppm. – Anal. for C12H12N4S (244.32): calcd. C
29.02; found C 64.93, H 6.26, N 28.89.
58.99, H 4.95, N 22.93; found C 58.84, H 4.99, N 3.08.
4.2.2 2-(1-Benzyl-1H-1,2,3-triazol-4-yl)-4,5-
4.2.4 2-(1-Benzyl-1H-1,2,3-triazol-4-yl)-1,4,5,6-
dihydrooxazole (L3)
tetrahydropyrimidine (L5)
To a suspension of amidinium salt 1 (200 mg, 0.35 mmol)
and anhydrous K3PO4 (210 mg, 1.000 mmol) in dry acetoni-
trile (12 mL) was added freshly distilled 2-aminoethanol
(25 μL, 0.40 mmol) and the mixture was kept with stirring
at reflux temperature for 18 h. After cooling, the solvent
was evaporated in vacuo. The residue was dissolved in
ethyl acetate–ethanol (87:13 v/v), alumina (1 g) was added,
the solvent mixture was evaporated and the residue was
placed on top of a column packed with alumina (40 g).
Chromatography with ethyl acetate–ethanol (87:13 v/v)
furnished L3 as a colorless crystalline solid (Rf ꢀ=ꢀ 0.41;
yield: 70 mg, 88%). M.p. 174.0–175.6°C. – IR (KBr):
The preparation of L5 followed the procedure described
above for L3, using salt 1 (300 mg, 0.52 mmol), anhydrous
K3PO4 (212 mg, 1.00 mmol) and 1,3-diaminopropane (50
μL, 0.59 mmol) in dry acetonitrile (20 mL). Reaction con-
ditions: 18 h at reflux temperature. Column chromatog-
raphy with ethyl acetate–ethanol (8:2) as eluent afforded
113 mg (91% yield) of L5 as a colorless solid (Rf ꢀ=ꢀ 0.32),
ꢀ
M.p. 157–159°C. – IR (KBr): ν = 3223 br m, 3150 m, 2936 m,
1630/1626 vs, 1573 vs, 1498 m, 1456 m, 1312 m, 1254 m, 1228
m, 1186 m, 1070 m, 1048 m, 998 m, 712 s, 696 m cm−1. – 1H
NMR (CDCl3): δ ꢀ=ꢀ 1.85 (quin, 3J ꢀ=ꢀ 5.7 Hz, 2 H, CH2CH2CH2),
3.45 (t, 3J ꢀ=ꢀ 5.7 Hz, 4 H, 2 NCH2), 5.49 (s, 2 H, PhCH2), 7.25–
ꢀ
ν = 3134 w, 3036 w, 1671 s, 1552 m, 1496 m, 1460 m, 1397
7.27 (m, 2 H, HPh), 7.33–7.45 (m, 3 H, HPh), 7.86 (s, 1 H, 5-Htriaz
)
m, 1367 m, 1290 m, 1246 m, 1213 m, 1195 m, 1140 m, 1102
ppm. – 13C NMR (CDCl3): δ ꢀ=ꢀ 21.0 (CH2CH2CH2), 41.7 (broad-
ened, NHCH2 and ꢀ=ꢀNCH2), 54.6 (PhCH2), 122.3 (C-5triaz);
128.5, 129.0, 129.3, 134.0 (all CPh); 145.3 (C-4triaz), 147.8 (NCꢀ=ꢀN)
ppm. – Anal. for C13H15N5 (241.29): calcd. C 64.71, H 6.27, N
29.02; found C 64.48, H 6.18, N 28.64.
1
m, 1053 s, 1004 m, 970 m, 935 m, 890 m, 720 s cm−1. – H
NMR (CDCl3): δ ꢀ=ꢀ 4.03 (t, 3J ꢀ=ꢀ 9.4 Hz, 2 H, NCH2), 4.44 (t,3J ꢀ=ꢀ
9.5 Hz, 2 H, OCH2), 5.57 (s, 2 H, PhCH2), 7.27–7.30 (m, 2 H,
HPh), 7.37–7.40 (m, 3 H, HPh), 7.89 (s, 1 H, 5-Htriaz) ppm. – 13C
NMR ([D4]methanol): δ ꢀ=ꢀ 54.8, 54.9 (NCH2 and PhCH2);
69.0 (OCH2); 127.2 (C-5triaz); 129.0, 129.6, 130.0 (all CPh); 136.1
and 137.8 (C-4triaz, CPh), 159.9 (C-2, oxazoline) ppm. – Anal.
for C12H12N4O (228.25): calcd. C 63.15, H 5.30, N 24.55; found 4.3 Syntheses of complexes
C 63.15, H 5.35, N 24.41.
4.3.1 Bis(1-benzyl-4-(4,5-dihydro-1H-
imidazol-2-yl)-1,2,3-triazole)copper(II)
4.2.3 2-(1-Benzyl-1H-1,2,3-triazol-4-yl)-4,5-
bis(trifluoromethanesulfonate), [Cu(L1)2](OTf)2
dihydrothiazole (L4)
To a solution of ligand L1 (50 mg, 0.2 mmol) in ethyl acetate
The preparation of L4 followed the procedure described (3 mL) was added a saturated solution of copper(II) tri-
above for L3, using salt 1 (90 mg, 0.16 mmol), anhydrous fluoromethanesulfonate (Cu(OTf)2) in ethyl acetate (2 mL).
K3PO4 (105 mg, 0.50 mmol) and 2-aminoethanethiol (16 A blue-green precipitate appeared within 10 min, which
mg, 0.21 mmol) in dry acetonitrile (12 mL). Reaction con- was transformed into green-brown hexagonal crystals
ditions: 24 h at reflux temperature. Column chromatogra- during slow evaporation of the solvent on standing with
phy with ethyl acetate-ethanol (8:2) as eluent furnished air contact. The crystals were collected by filtration with
34 mg (88% yield) of L4 as a light yellow solid (Rf ꢀ=ꢀ 0.53), suction, washed with a small volume of ethyl acetate to
ꢀ
M.p. 141–143°C. – IR (KBr): ν = 3138 m, 3001 w, 1627 s, remove co-precipitated Cu(OTf)2. Yield: 85 mg (95%); M.p.
ꢀ
1531 m, 1496 m, 1455 m, 1428 m, 1301 m, 1229 m, 1168 m, 272–274°C. – IR (KBr): ν = 3262 m br (NH), 3147 w, 3103
1039 m, 1001 s, 913 s, 823 m, 771 s, 666 m cm−1. – 1H NMR w, 1645 m, 1597 s, 1296 vs, 1253 vs, 1228 s, 1148 s, 1076 m,
(CDCl3): δ ꢀ=ꢀ 3.39 (t, 3J ꢀ=ꢀ 8.5 Hz, 2 H, SCH2), 4.38 (t, 3J ꢀ=ꢀ 8.5 1059 m, 1029 vs, 757 w, 729 s, 629 s, 575 m, 520 m cm−1. –
+
Hz, 2 H, NCH2), 5.56 (s, 2 H, PhCH2), 7.28–7.30 (m, 2 H, HPh), MS ((+)-MALDI-TOF): m/z (%) ꢀ=ꢀ 666.24 (100) [M–CF3SO3] ,
+
+
7.36–7.40 (m, 3 H, HPh), 7.87 (s, 1 H, 5-Htriaz) ppm. – 13C NMR 516.26 (15) [M–2CF3SO3–H] , 228.16 (74) [L1+H] . – Anal. for
(CDCl3): δ ꢀ=ꢀ 31.9 (SCH2), 53.4 (PhCH2), 63.6 (NCH2), 121.7 C26H26CuF6N10O6S2 (816.21): calcd. C 38.26, H 3.21, N 17.16;
(C-5triaz); 127.3, 128.0, 128.2, 132.8 (all CPh); 142.0 (C-4triaz), found C 38.25, H 3.49, N 16.92.
Unauthenticated
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ꢁꢀꢀꢀ
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ
ꢂ11
4.3.2 [CuL2L2′(OTf)2] · 2 H2O
in n-butanol (3 mL). Diethyl ether was placed on top of the
blue butanol layer. After several weeks, deep blue crystal
Ligand L2/L2′ (15.2 mg, 63 μmol) was dissolved in ethyl platelets separated which were isolated by filtration with
acetate (5 mL) and a solution of Cu(OTf)2 (11.4 mg, 31.5 suction, washed with a small volume of diethyl ether and
μmol) in ethyl acetate (3 mL) was added. The blue precipi- dried at air. Yield: 64 mg (91); M.p. 271–275°C. – IR (KBr):
ꢀ
tate was isolated by filtration with suction and dried at air; ν = 3322 br, 3154 w br, 3063 w, 1641 m, 1613 s, 1453 m, 1284
yield: 26 mg (98%). Crystals suitable for X-ray diffraction vs, 1256 vs, 1225 vs, 1167 s, 1032 vs, 759 m, 700 s, 639 vs,
analysis were obtained when a solution of the precipitate 576 m, 518 m cm−1. – Anal. for C28H30CuF6N10O6S2 (844.27):
in the necessary amount of ethyl acetate was concentrated calcd. C 39.83, H 3.58, N 16.59; found C 40.07, H 3.74, N 16.16.
by slow evaporation. M.p. 255.5–256.5°C. – IR (KBr): IR
ꢀ
(KBr): ν = 3259 s br (NH), 3151 w, 1643 m, 1591 s, 1500 m,
4.3.5 Bis(2-(1-benzyl-1H-1,2,3-triazol-4-yl)-4,5-dihydro-
1H-imidazole)dichloridocopper(II) tetrahydrofuran
solvate, [Cu(L1)2Cl2]
1285 vs, 1243 vs, ~1228 sh, 1159 s, 1028 vs, 720 m, 636 s,
574 w, 518 m cm−1. – MS ((+)-MALDI-TOF): m/z (%) ꢀ=ꢀ 694.15
+
(100) [M–CF3SO3] , 1539.24 (8) [2 [CuL2L2′(OTf)2]–OTf]. –
Anal. for C28H30CuF6N10O6S2 (844.27), water-free sample:
calcd. C 39.83, H 3.58, N 16.59; S 7.59; found C 39.62, H 3.41,
N 16.64, S 7.61.
Ligand L1 (34.5 mg, 150 μmol) was dissolved in ethyl
acetate (5 mL) and a solution of CuCl2 (10.2 mg, 75 μmol) in
ethyl acetate (3 mL) was added. A light green precipitate
appeared, which was isolated by filtration with suction,
washed with a small volume of pentane and dried at air;
yield: 42 mg (95%); M.p. 238–239.5°C (dec.). – IR (KBr):
4.3.3 Diaquabis(2-(1-benzyl-1H-1,2,3-triazol-
4-yl)-4,5-dihydro-1,3-thiazole)copper(II)
bis(trifluoromethanesulfonate) · bis(2-(1-benzyl-
1H-1,2,3-triazol-4-yl)-4,5-dihydrothiazole)
bis(trifluoromethanesulfonato-κO)copper(II),
[Cu(L4)2(H2O)2](OTf)2 · [Cu(L4)2(OTf)2]
ꢀ
ν = 3424 m br, 3088 m, 1629 m, 1591 s, 1569 m, 1498 w,
1290 w, 1276 w, 1257 w, 1064 m, 719 m, 578 w cm−1. – MS
((+)-MALDI): m/z (%) ꢀ=ꢀ 552.13 (100) [M–Cl]; C24H26ClCuN10
requires 552.1326. – C24H26Cl2CuN10 (588.98).
Ligand L4 (110 mg, 0.45 mmol) was dissolved in a small 4.3.6 Bis(2-(1-benzyl-1H-1,2,3-triazol-4-yl)-4,5-
3
volume of ethyl acetate and a saturated solution of
copper(II) trifluoromethanesulfonate in ethyl acetate was
added. An amorphous light blue precipitate was formed,
dihydro-1,3-oxazole-κN )dichloridocopper(II)
tetrahydrofuran solvate, [Cu(L3)2Cl2] · THF
isolated by filtration and dried at air; yield: 180 mg (94%). Ligand L3 (16.8 mg, 0.10 mmol) was dissolved in dry THF
The solid was redissolved in the necessary volume of (3 mL) and a saturated light green solution of CuCl2 in dry
ethyl acetate and this solution was concentrated by slow THF (2 mL) was gradually added, until the color of the
evaporation with exposure to air. With uptake of water resulting solution had changed from green to deep blue.
molecules, light blue prismatic crystals suitable for X-ray The solvent was slowly concentrated by evaporation, until
analysis were formed. The crystals lost water at 180–182°C dark blue prismatic crystals appeared. They were isolated
ꢀ
ν = 3447 w br (OH),
and melted at 225–228°C. – IR (KBr):
by filtration with suction and dried at air. Yield: 26.5 mg
3100 w (N–H), 3069 w, 1616 m, 1543 m, 1458 m, 1286 vs, (80%, for the THF solvate). The crystals lost THF at 106°C
1
1246 vs, 1224 s, 1158 s, 1112 m, 1060 m, 1028 s, 721 m, 636 s, and melted at 169–171°C. – H NMR (CDCl3): δ ꢀ=ꢀ 1.89 (m,
575 w, 518 w cm−1. – MS ((+)-MALDI-TOF): m/z (%) ꢀ=ꢀ 700.15 4 H, CH2CH2 of THF), 3.74 (m, 4 H, CH2OCH2 of THF), 4.64
(100) [M–CF3SO3]. – Anal. for C26H24CuF6N8O6S4 (850.32), (broad s, 8 H, NCH2CH2O), 5.49 (broad s, 2 H, 5-H), 6.66
water-free sample: calcd. C 36.72, H 2.84, N 13.18; found C (broad s, 4 H, PhCH2), 7.39–7.55 (m, 10 H, HPh) ppm. – Anal.
36.55, H 2.87, N 13.27.
for C24H26Cl2CuN8O2 · C4H8O (663.06): calcd. C 50.72, H 4.86,
N 16.90; found C 50.64, H 5.02, N 17.35.
4.3.4 Bis(2-(1-benzyl-1H-1,2,3-triazol-4-yl)-1,4,5,6-
tetrahydropyrimidine)-bis(trifluoromethanesulfonato- 4.3.7 Bis(1-benzyl-4-(4,5-dihydro-1H-imidazol-2-yl)-
κO)copper(II), [Cu(L5)2(OTf)2]
1,2,3-triazole)dichloridonickel(II), [Ni(L1)2Cl2]
A saturated solution of Cu(OTf)2 in n-butanol was added To a solution of ligand L1 (38.5 mg, 169 μmol) in 1-butanol
drop by drop to a solution of ligand L5 (40 mg, 0.16 mmol) (5 mL) was added a solution of NiCl2ꢀ×ꢀ6H2O (20.1 mg,
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ꢀꢀꢀꢁ
12ꢀ ꢀS. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine
Table 4:ꢀCrystal structure data for [Cu(L1)2](OTf)2, [CuL2L2′(OTf)2] and [Cu(L5)2(OTf)2].
ꢁ
[Cu(L1)2](OTf)2
ꢁ
[CuL2L2′(OTf)2] · 2H2O
ꢁ
[Cu(L5)2(OTf)2]
Formula
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C26H28CuF6N8O8S4 ·C26H24CuF6N8O6S4ꢃ
C28H30CuF6N10O6S2 · 2H2O ꢃ
C28H30CuF6N10O6S2
844.28
0.25 ꢃ×ꢃ 0.11 ꢃ×ꢃ 0.09
180(2)
monoclinic
P21/c
25.7804(7)
13.1928(4)
10.0657(2)
90.448(2)
3423.41(15)
4
1.64
2.86
1724
CuK /1.54184
31α, –14:+16, 12
74.16
20153
6734/0.0216
486
Mr
1736.63
0.27 ꢃ×ꢃ 0.22 ꢃ×ꢃ 0.12
100(2)
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
880.31
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Cryst. size, mm3
0.30 ꢃ×ꢃ 0.16 ꢃ×ꢃ 0.13
180
monoclinic
P21
Temperature, K
Crystal system
monoclinic
P21/c
Space group
a, Å
b, Å
c, Å
β, °
V, Å3
Z
10.6449(4)
17.6042(6)
8.6745(3)
99.510(2)
1603.22(10)
2
8.9026(3)
16.4389(5)
13.4275(5)
104.194(4)
1905.10(11)
2
D
calcd., g cm−3
1.691
1.535
μ, mm−1
0.906
0.772
F(000), e
830
902
Radiation/λ, Å
hkl range
θmax, °
MoK /0.71073
15,α 25, –12:+11
30.54
MoKα/0.71073
–8:+11, 20, –16:+13
29.17
Refl. measured
Refl. unique/Rint
Param. Refined
34440
4903/0.0237
292
10580
6730/0.0229
498
0.0524/0.1296
1.015
–0.005(14)
0.69/–0.41
1446994
R(F)/wR(F2)a (all refl.) ꢃ
0.0385/0.0976
1.080
0.0629/0.1423
1.062
–
1.32/–0.51
1447013
GoF (F2)a
ꢃ
ꢃ
ꢃ
ꢃ
x(Flack)
–
Δρfin (max/min), e Å−3
CCDC no.
0.65/–0.79
1446997
2
2
2
aR(F) ꢃ=ꢃ Σ||Fo|–|Fc||/Σ|Fo|; wR(F2) ꢃ=ꢃ [Σw(Fo –Fc2)2/Σw(Fo )2]1/2; GoF ꢃ=ꢃ S ꢃ=ꢃ [Σw(Fo –Fc2)2/(nobs–nparam)]1/2
.
84 μmol) in 1-butanol (3 mL). On standing for about 3 the University of Ulm and a Bruker Kappa APEX II Duo
diffractometer at the University of Stuttgart. Software
for structure solution and refinement: Shelxs/l-97 [38]
and Shelxl-2014/6 [39]; molecule plots: Ortep-iii [40,
41] and Mercury [42]. In all Ortep plots, the size of
the displacement ellipsoids represents 30% probabil-
ity. In the refinement procedure, hydrogen atoms were
usually placed in geometrically calculated positions and
treated as riding on their bond neighbors in the refine-
ment. NH and OH hydrogen atom positions were taken
from a difference-Fourier electron density map and
were refined. Further details are provided in Tables 4
and 5. For [CuL2L2′(OTf)2] · 2H2O, which crystallizes in
the noncentrosymmetric space group P21, the correct
absolute structure is supported by the value of the Flack
parameter.
weeks, light green crystals appeared which were col-
lected by filtration with suction and dried at air (37 mg,
75% yield). The crystals did not melt up to 326°C, only a
color change to dark brown was observed beyond this
ꢀ
temperature. – IR (KBr): ν = 3164 s (N–H), 3091 m, 1641
s, 1580 s, 1497 m, 1479 m, 1456 m, 1282 m, 1263 m, 1243 m,
1067 m, 1032 m, 720 m cm−1. – MS ((+)-MALDI): m/z (%) ꢀ=ꢀ
547.14 (99) [M–Cl], 511.16 (100) [M–2Cl–H]; required:
547.14, 511.16. – Anal. for C24H26Cl2N10Ni (584.13): calcd.
C 49.35, H 4.49, N 23.98. A correct analysis could not be
obtained.
4.4 X-ray structure determinations
CCDC 1446994, 1446997 and 1447013–1447016 contain
the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.
Suitable single crystals of the investigated complexes
were obtained as described above in the synthetic pro-
cedures. Data collection was performed on an Oxford
SuperNova diffractometer (dual source, Atlas CCD) at ac.uk/data_request/cif.
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ꢁꢀꢀꢀ
S. Schröder et al.: 2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidineꢂ
ꢂ13
Table 5:ꢀCrystal structure data for [Cu(L4)2(H2O)2](OTf)2 · [Cu(L4)2(OTf)2], [Cu(L3)2Cl2] · THF and [Ni(L1)2Cl2]2].
ꢁ
[Cu(L4)2(H2O)2](OTf)2 · [Cu(L4)2(OTf)2]ꢁ
[Cu(L3)2Cl2] · THF
ꢁ
[Ni(L1)2Cl2]
Formula
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C26H26CuF6N8O7S4
868.33
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C24H24Cl2CuN8O2 · C4H8O
663.07
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
C24H26Cl2N10Ni
Mr
584.16
Cryst. size, mm3
0.22 ꢃ×ꢃ 0.17 ꢃ×ꢃ 0.08
150(2)
0.22 ꢃ×ꢃ 0.17 ꢃ×ꢃ 0.15
150(2)
0.16 ꢃ×ꢃ 0.09 ꢃ×ꢃ 0.06
150(2)
orthorhombic
Pbcn
Temperature (K)
Crystal system
triclinic
monoclinic
C2/c
̅
P1
Space group
a, Å
b, Å
c, Å
α, °
β, °
γ, °
V, Å3
Z
7.7753(3)
13.8579(5)
16.3674(7)
85.302(3)
89.710(3)
86.194(3)
1753.77(12)
2
23.5405(6)
8.8545(2)
15.5836(4)
90
11.9140(2)
9.5622(2)
22.9451(4)
90
113.347(3)
90
90
90
2982.28(13)
4
2613.99(7)
4
D
calcd., g cm−3
1.644
1.477
1.484
μ, mm−1
0.948
0.957
0.324
F(000), e
882
1372
1208
Radiation/λ, Å
hkl range
MoK /0.71073
–9:+α8, 16, 19
24.71
MoKα/0.71073
CuK /1.54184
14α, –11:+10,–28:+20
73.89
–28:+30, –12:+9, –18:+19ꢃ
θmax, °
29.18
8706
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
ꢃ
Refl. measured
Refl. unique/Rint
Param. refined
R(F)/wR(F2)a (all refl.)
GoF (F2)a
19843
7812
5972/0.0387
480
3523/0.0204
205
2586/0.0224
172
0.0623/0.0958
0.952
0.0451/0.1038
1.047
0.0340/0.0724
1.035
Δρfin (max/min), e Å−3
CCDC no.
0.90/–0.67
1447014
0.83/–0.61
1447015
0.26 /–0.18
1447016
2
2
2
aR(F) ꢃ=ꢃ Σ||Fo|–|Fc||/Σ|Fo|; wR(F2) ꢃ=ꢃ [Σw(Fo –Fc2)2/Σw(Fo )2]1/2; GoF ꢃ=ꢃ S ꢃ=ꢃ [Σw(Fo –Fc2)2/(nobs–nparam)]1/2
.
[14] D. Wang, D. Denux, J. Ruiz, D. Astruc, Adv. Synth. Catal. 2013,
355, 129.
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Dalton Trans. 2014, 43, 7069.
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Acknowledgments: We thank Bernhard Müller and Dieter
Sorsche for the X-ray data collection at Ulm.
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Z. Naturforsch.ꢂ
ꢂ2016 | Volume x | Issue x(b)
Graphical synopsis
Sven Schröder, Wolfgang Frey and
Gerhard Maas
2-(1,2,3-Triazol-4-yl)-imidazoline,
-oxazoline, -thiazoline and -tetrahydro-
pyrimidine as ligands in copper(II) and
nickel(II) complexes
DOI 10.1515/znb-2016-0026
Z. Naturforsch. 2016; x(x)b: xxx–xxx
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