Highly pyramidalised heteroaromatic nitrogens in discrete multinuclear silver(i) complexes assembled from bis- and tris-(diallylamino)azines

Article abstract of DOI:10.1039/c3ce41708e

2,4-Bis(diallylamino)-6-chloro-1,3,5-triazine reacts with silver(i) perchlorate and triflate to form discrete M₄L₂ assemblies in which the ligand uses all seven available (allyl and triazine) donors. 2,4,6-Tris(diallylamino)pyrimidine forms a discrete M₂L complex with silver triflate, in which the ligand is hypodentate. 2,4,6-Tris(diallylamino)-1, 3,5-triazine forms a 1-D coordination polymer with silver perchlorate using seven donor groups, but employs all nine donors to form a discrete M ₃L complex with silver triflate. In all these structures the nitrogen donors show unusually high levels of pyramidalisation.

Full text of DOI:10.1039/c3ce41708e

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Highly pyramidalised heteroaromatic nitrogens in
discrete multinuclear silver(I) complexes assembled
from bis- and tris-(diallylamino)azines†
Cite this: CrystEngComm, 2013, 15,
9072
*
Solomon W. Kelemu and Peter J. Steel
2,4-Bis(diallylamino)-6-chloro-1,3,5-triazine reacts with silver(I) perchlorate and triflate to form discrete M4L2
assemblies in which the ligand uses all seven available (allyl and triazine) donors. 2,4,6-Tris(diallylamino)pyrimidine
forms a discrete M2L complex with silver triflate, in which the ligand is hypodentate. 2,4,6-Tris(diallylamino)-1,3,5-
triazine forms a 1-D coordination polymer with silver perchlorate using seven donor groups, but employs all nine
donors to form a discrete M3L complex with silver triflate. In all these structures the nitrogen donors show unusu-
ally high levels of pyramidalisation.
Received 27th August 2013,
Accepted 19th September 2013
DOI: 10.1039/c3ce41708e
www.rsc.org/crystengcomm
Introduction
allyl bromide gave ligand (2) in 97% yield. Reaction of
cyanuric chloride with three equivalents of diallylamine
Silver(I) has proved to be a particularly useful metal for the
self-assembly of a diverse range of metallosupramolecular
species.1–6 For some time we have used this metal for coordi-
nation to various nitrogen heterocyclic ligands for the assem-
bly of both discrete and polymeric structures with diverse
molecular architectures.7–11 More recently, we12–14 and
others,15–23 have shown that coordination of silver(I) to
alkenes is a useful synthon in metallosupramolecular chemis-
try. In the accompanying paper24 we combined these two
furnished the symmetrical six armed ligand (3), albeit in only
28% yield. The ligands were isolated as yellow oily liquids
after column chromatography on silica gel and were
1
characterised by H and 13C NMR, infrared spectroscopy and
mass spectrometry. Both the 1H and 13C NMR spectra of
ligand (1) were more complicated than expected as the two
allyl groups on each diallylamino group are non-equivalent
due to restricted rotation about the N–triazine bond. Such
a phenomenon has previously been noted in other dialky-
lamino triazines.25
approaches and showed that ligands containing
a
diallylamino group attached to a nitrogen heterocycle consis-
tently lead to 1-D coordination polymers with coordination by
the heterocyclic nitrogen and the allyl arms of the ligand. We
now extend this approach to ligands containing two or three
diallylamino groups attached to highly electron deficient het-
erocycles, which leads to (mainly) discrete assemblies in
which the ligands gather together multiple silver atoms. A fea-
ture of these structures is the coordination of heterocyclic
nitrogens with unusually highly pyramidalised geometries.
Reaction of ligand (1) with two equivalents of silver(I) per-
chlorate and triflate gave crystalline complexes (4) and (5) in
15% and 78% yields, respectively. Complex (4), [Ag4(1)2](ClO4)4,
¯
crystallises in the triclinic space group P1. The asymmetric unit
contains one full molecule of (1), two silver atoms, a coordi-
nated water molecule, a non-coordinated acetone molecule
and two non-coordinated perchlorate counterions. The struc-
ture exists as a discrete tetranuclear (M4L2) assembly at the
centre of which lies a crystallographic centre of inversion, as
shown in Fig. 2. This involves the coordination of two ligand
molecules with four silver atoms using all of the allyl arms and
the three triazine ring nitrogen atoms.
Results and discussion
The structures and syntheses of the ligands employed in this
study are shown in Fig. 1. Reaction of cyanuric chloride with
two equivalents of diallylamine gave the four armed ligand
(1) in 72% yield. Alkylation of 2,4,6-triaminopyrimidine with
The two crystallographically independent silver atoms
are each four-coordinate, with τ4 values26 of 0.71 and 0.79
for Ag1 and Ag2 respectively, indicating seesaw geometries.
Ag1 binds to two adjacent ligand molecules through the
coordination of two allyl arms and two nitrogen atoms
from triazine rings of adjacent ligands. In contrast, Ag2 is
coordinated to two allyl arms of the same ligand, a nitro-
gen atom of the triazine ring and a water molecule. It is
noteworthy that no two allyl arms from a single diallylamine
Department of Chemistry, University of Canterbury, Christchurch 8020, New Zealand.
E-mail: peter.steel@canterbury.ac.nz; Fax: +64 3 3642110; Tel: +64 3 3642432
† CCDC 940158 (4), 940159 (5), 940160 (6), 940161 (7) and 940162 (8). For
crystallographic data in CIF or other electronic format see DOI: 10.1039/
c3ce41708e
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(d) of the silver atom from the meanplane of the triazine ring
and the N–Ag bond length (l), where sin (α) = d/l. An α angle
of 0° would correspond to a trigonal planar sp2 hybridised
nitrogen, while a tetrahedral nitrogen would have an α angle
of 54.75°. In the present case the α angles for N1, N2 and N3
are 42.2°, 51.7° and 35.0°, respectively, which represent
unusually high degrees of pyramidalisation. Clearly the coor-
dination of the silver to the nitrogen involves some contribu-
tion of the nitrogen p orbital, i.e. there is a rehybridisation of
the sp2 nitrogen towards sp3. We believe that this is possible
due to the low aromatic stabilisation energy of the highly
electron deficient triazine ring, and is facilitated by the fact
that the diallylamino nitrogen donates electron density into
the triazine ring. This requires the exocyclic nitrogen p orbital
to be coplanar with the ring which increases the steric envi-
ronment at the ring nitrogens in the plane of the ring.
Although unusual, such pyramidalisation does exist in some
structures in the literature. For example, a silver complex of a
bis(oxazolinyl)pyridine has a pyramidalised pyridine nitrogen
with an α angle of 24°.28
Fig. 1 Synthesis of the ligands employed in this study.
Fig. 3 Definition of the pyrimidalisation angle α.
group coordinate with the same silver atom. The two indepen-
dent silver atoms are separated by a distance of 6.620(1) Å,
while symmetry related silvers are separated by 5.591(1) Å
(Ag1) and 12.073(1) Å (Ag2).
Within this structure another feature of interest is the
relative orientations of the two triazine rings, which posi-
tions the two chlorine atoms far from each other but close
to the triazine ring of the other ligand. This arrangement
results in mutual halogen–π interactions, with the distance
between the centroid of the triazine ring and the chlorine
atom being 3.259(5) Å, which represents a relatively strong
interaction.29 Finally, we note that the coordinated water
molecule is hydrogen bonded to two non-coordinated per-
chlorate oxygen atoms.
Other weak intermolecular interactions are apparent in
the crystal packing but play no obvious role in the self-
assembly of this structure. Attempts to characterise this com-
plex by mass spectrometry showed only ions from the
uncomplexed ligand, indicating that this structure disassem-
bles upon redisolving it in acetonitrile.
Whereas the Ag–C bond distances (Table 1) fall in the
normal range for silver alkene interactions,12 the Ag–N bond
distances are relatively long (2.408(1)–2.627(1) Å) but still
shorter than those in previously reported silver complexes of
related triazines.18,27 However, an intriguing aspect of the
structure is the unusually high pyramidalisation of the coor-
dinated triazine nitrogens. In order to measure the extent of
this distortion, we define the “pyramidalisation angle”, α, as
the angle subtended by the N–Ag vector to the plane of the
ring, as shown in Fig. 3. This is determined from the distance
The analogous silver triflate complex (5), [Ag4(1)2(OTf)2](OTf)2,
¯
crystallises in the trigonal space group R3, with one molecule of
(1), two silver atoms, one coordinated and one non-coordinated
triflate counterion in the asymmetric unit, all of which again
assemble into a M4L2 structure (Fig. 4). Despite the very different
space group and counterion, the structure is very similar to that
of complex (4). The major difference is the replacement of the
coordinated water molecule in complex (4) by a coordinated
triflate anion in (5). A more subtle difference is the longer Ag2–N2
bond distance (Table 1), which presumably results from the
greater steric demand of the coordinated triflate in (5), com-
pared to the water molecule in (4). Other structural parame-
ters are remarkably similar, including the pyramidalisation
Fig. 2 The tetranuclear M4L2 discrete assembly of complex (4). All hydrogen
atoms, the non-coordinated acetone molecule and the perchlorate counterions have
been omitted for clarity.
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Table 1 Selected bond lengths and angles. Note: CX,CY represents the midpoint of the bond between CX and CY
Complex (4)
Complex (5)
2.311(3) Ag1–N3A
2.408(3) Ag1–C8A,C9A
2.537(3) Ag1–N1
2.360(3) Ag1–C11,C12
2.333(3) Ag2–C5,C6
2.627(3) Ag2–C14,C15
2.357(4) Ag2–O2
Complex (6)
2.414(4) Ag1–N2
Complex (7)
2.478(4) Ag1–N3
2.291(2) Ag1–C8,C9
2.283(2) Ag1–C11,C12
2.482(4) Ag1–C29,C30
2.391(2) Ag2–N2
2.287(2) Ag2–C5,C6
2.335(2) Ag2–O2
2.530(4) Ag2–C17,C18
2.390(4) Ag3–N7
Complex (8)
Ag1–C8A,C9A
Ag1–N3
Ag1–N1A
Ag1–C11,C12
Ag2–O9
Ag2–N2
2.486(4) Ag1–C8,C9
2.363(2) Ag1–C17,C18
2.331(2) Ag1–N3
2.359(2) Ag2–C5,C6
2.527(4) Ag2–C11,C12
2.300(1) Ag2–N1
2.519(2) Ag2–O2
2.313(1) Ag3–O4
2.500(4) Ag3–N2
2.373(2) Ag3–C14,C15
2.338(1) Ag3–C20,C21
2.369(2)
2.308(4)
2.334(4)
2.485(3)
2.281(4)
2.289(4)
2.458(3)
2.407(3)
2.349(3)
2.508(3)
2.331(4)
2.324(4)
2.337(2) Ag1–C6,C7
2.445(4) Ag1–C21,C22
2.332(1) Ag2–N1
2.374(1) Ag2–O3
2.373(2) Ag2–C12,C13
2.410(4) Ag2–C18,C19
2.669(1) Ag3–N6
Ag3–O6
Ag2–C5,C6
Ag2–C14,C15
2.306(4) Ag2–N2
Ag3–C32,C33
Ag3–C38,C39
Ag4–N7
Ag4–C29,C30
2.334(2) Ag3–C20,C21
2.327(2) Ag3–C35,C36
2.637(4) Ag3–C41,C42
2.326(2) Ag4–N8
2.628(4)
Ag4–C44,C45
Ag4–O5
2.327(2) Ag4–C26,C27
2.319(4) Ag4–C38,C39
2.296(1)
2.273(2)
N3–Ag1–C11,
C12
N3–Ag1–N1A
88.6(1)
99.2(2)
N3A–Ag1–C8A,
C9A
N3A–Ag1–C11, 127.1(2)
C12
N1–Ag1–C8A,
C9A
C8A,C9A–Ag1– 120.7(2)
C11,C12
N1–Ag1–C11,
C12
C5,C6–Ag2–
C14,C15
91.7(2)
N2–Ag1–C6,C7
91.2(1)
95.4(2)
N3–Ag1–C8,C9
92.2(2)
90.5(2)
N3–Ag1–C8,C9
92.7(1)
90.8(2)
136.1(1)
80.2(1)
95.5(2)
91.2(2)
N2–Ag1–C21,
C22
C6,C7–Ag1–
C21,C22
N3–Ag1–C11,
C12
N3–Ag1–C29–
C30
C8,C9–Ag1–
C11,C12
C8,C9–Ag1–
C29,C30
N3–Ag1–C17,
C18
C8,C9–Ag1–
C17,C18
N3–Ag1–C8A,
C9A
C11,C12–Ag1– 125.3(2)
N1A
C8A,C9A–Ag1– 122.9(2)
C11,C12
134.5(2)
128.5(1)
136.1(2)
112.0(2)
91.3(1)
101.2(2)
128.6(2)
111.9(2)
N1–Ag2–O3
N1–Ag2–O2
89.5(2)
N1–Ag2–C12,
C13
N1–Ag2–C18,
C19
N1–Ag2–C5,C6
N1A–Ag1–C8A,
C9A
88.5(1)
150.4(2)
91.5(1)
C11,C12–Ag1– 117.8(2)
C29,C30
N1–Ag2–C11,
C12
O9–Ag2–N2
91.4(1)
C5,C6–Ag2–O2 101.2(2)
O3–Ag2–C12,
C13
O3–Ag2–C18,
C19
C12,C13–Ag2– 131.1(3)
C18,C19
N6–Ag3–O6
N6–Ag3–C32,
C33
N6–Ag3–C38,
C39
O6–Ag3–C32,
C33
O6–Ag3–C38,
C39
123.1(3)
100.7(3)
N2–Ag2–O2
77.7(2)
95.8(2)
89.8(2)
O2–Ag2–C5,C6 100.8(2)
O9–Ag2–C5,C6 111.1(2)
C14,C15–Ag2– 108.5(2)
O2
N2–Ag2–C5,C6
O2–Ag2–C11,
C12
C5,C6–Ag2–
C11,C12
O4–Ag3–N2
O4–Ag3–C14,
C15
118.3(2)
140.8(2)
O9–Ag2–C14,
C15
N2–Ag2–C5,C6
N2–Ag2–C14,
C15
C5,C6–Ag2–
C14,C15
119.2(2)
N2–Ag2–C17,
C18
O2–Ag2–C5,C6 113.6(3)
O2–Ag2–C17,
C18
C5,C6–Ag2–
C17,C18
N7–Ag3–C20,
C21
N7–Ag3–C35,
C36
86.4(2)
88.2(2)
90.8(1)
89.1(2)
94.4(1)
116.7(2)
108.6(3)
137.6(2)
105.1(2)
89.9(2)
129.6(2)
93.1(2)
119.7(2)
107.0(2)
O4–Ag3–C20,
C21
N2–Ag3–C14,
C15
N2–Ag3–C20,
C21
112.2(2)
89.7(2)
90.7(2)
C32,C33–Ag3– 133.1(2)
C38,C39
N7–Ag3–C41,
C42
91.1(2)
C14,C15–Ag3– 130.9(2)
C20,C21
N7–Ag4–O5
81.5(1)
85.9(2)
C20,C21–Ag3– 112.3(2)
C41,C42
C20,C21–Ag3– 119.0(2)
C35,C36
N7–Ag4–C29,
C30
N7–Ag4–C44,
C45
O5–Ag4–C29,
C30
O5–Ag4–C44,
C45
88.1(2)
C35,C36–Ag3– 127.4(2)
C41,C42
119.3(2)
110.2(2)
N8–Ag4–C26,
C27
89.3(2)
N8–Ag4–C38,
C39
87.8(2)
C29,C30–Ag4– 128.6(2)
C44,C45
C26,C27–Ag4– 175.7(2)
C38,C39
angles, the geometries of the silver atoms, the various dis-
tances between silver atoms separated by the bridging ligand
(1) and the intramolecular halogen–π interactions.
Ligands (2) and (3) expand the number of allyl arms from
four to six and differ not only in the symmetry of the ligand
itself7 but also in the number of available nitrogen donors
from the central arene core. The complex (6), [Ag2(2)OTf](OTf),
of ligand (2) with silver(I) triflate crystallises in the monoclinic
space group P21/c. The asymmetric unit contains two crystallo-
graphically independent assemblies (Fig. 5), each of which has
one full molecule of (2), two silver atoms and a coordinated
triflate counterion. There are also two non-coordinated triflate
anions. The main difference between the two M2L assemblies
is in the manner in which the coordinated triflate anion
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Ligand (3) possesses six symmetry related allyl arms and
three triazine nitrogens as potential donors. Reaction of
this ligand with silver(I) perchlorate gave a complex (7),
[Ag4(3)2(ClO4)]n(ClO4)3n, that crystallises in the orthorhombic
space group P212121, as a racemic twin. The asymmetric unit
contains two molecules of (3), four silver atoms, one coordi-
nated and three non-coordinated perchlorate anions (Fig. 6a).
In this case the structure assembles into a helical 1-D coordi-
nation polymer that propagates along the a axis (Fig. 6b).
Within the structure both molecules of (3) use five of their six
allyl arms and two of the three ring nitrogens for coordination
and are ambivergent,31 acting in both a chelating and bridg-
ing mode.
Fig. 4 The tetranuclear dimeric discrete assembly of complex (5). All hydrogen
atoms and the non-coordinated triflate counterions have been omitted for clarity.
The silver atoms are either coordinated with three allyl
groups (Ag1 and Ag3) or with two (Ag2 and Ag4). No two
allyl arms from the same diallylamine group chelate with a
single silver atom, rather the coordinated allyl arms are
either from adjacent diallylamine groups or adjacent
ligands. Including the other (N and O) donors, Ag1, Ag2 and
Ag3 are four-coordinate, while Ag4 is three-coordinate. The
four-coordinate silvers have seesaw geometries with τ4 values
of 0.81, 0.77 and 0.81 for Ag1, Ag2 and Ag3, respectively,
while the three-coordinate Ag4 atom has a T-shaped geome-
try (Table 1). Ag1 and Ag2 are bridged by the same ligand
with a separation distance of 6.505(1) Å, while the corre-
sponding distance between Ag3 and Ag4 is 6.664(1) Å. Ag2
and Ag3 are bridged by two allyl arms from the same
diallylamine group with a separation distance of 7.947(1) Å.
Unlike the earlier examples, the silver atoms coordinate
to the ring nitrogens on opposite faces of the ring. These
nitrogens are again highly pyramidalised with α angles rang-
ing between 40.6° and 48.6°. In this complex ligand (3) acts
as a bridging ligand leading to a 1-D coordination polymer.
Fig. 5 The two independent units of complex (6). The non-coordinated triflate
counterions and all hydrogen atoms have been omitted for clarity.
presents itself to the binuclear complex. Whilst the triflate
anion is positioned in approximately the same position, in one
case it is coordinated in a monodentate manner to just one of
the silver atoms, with a very weak (2.642(2) Å) fourth interac-
tion between Ag1 and O2, but in the other it has a bridging
bidentate coordination mode. Thus three of the silvers are
four-coordinate, while Ag1 is pseudo three-coordinate.
A notable feature of this structure is that in both assem-
blies ligand (2) is hypodentate,30 with two of the six allyl
arms remaining non-coordinated. Once again no two allyl
arms from the same diallylamine group are chelated with a
silver atom. Each molecule of (2) uses four allyl arms and the
two pyrimidine nitrogens for coordination. The Ag–N bond
distances (Table 1) are relatively long, ranging from 2.487(4)
to 2.637(4) Å, with the shortest bond being to the pseudo
three-coordinate silver. The pyrimidine ring nitrogens are
again highly pyramidalised with α angles ranging between
47.6° and 55.3°.
The pseudo three-coordinate silver has a highly distorted
trigonal planar geometry, while the four-coordinate silvers
have seesaw geometries with τ4 values of 0.75, 0.76 and
0.80 for Ag2, Ag3 and Ag4, respectively. The ligand bridges
Ag1 and Ag2 with a separation of 4.976(1) Å; the corre-
sponding separation of Ag3 and Ag4 is 5.147(1) Å. Thus
ligand (2) acts by gathering together two silver atoms on
the same face of the ligand and these are capped by a coor-
dinated triflate anion.
Fig. 6 (a) The asymmetric unit of complex (7) showing the labels of coordinated
atoms. All hydrogen atoms and non-coordinated perchlorate anions are omitted for
clarity (8). (b) A section of the 1-D polymer of (7).
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an electrothermal melting point apparatus and are uncorrected.
Elemental analyses were carried out by the Campbell Microana-
lytical Laboratory, University of Otago.
Infrared spectra were recorded on
a Perkin-Elmer
Spectrum One FTIR instrument operating in diffuse reflec-
tance mode with samples prepared as KBr mulls (KBr), or in
transmittance mode with liquid samples pressed between
KBr discs (neat). NMR spectra were recorded on a Varian
INOVA 500 or Varian Unity 300 instrument, operating at 500
and 300 MHz, respectively, for 1H, and 125 and 75 MHz,
respectively, for 13C. Mass spectra were recorded on either a
DIONEX Ultimate 3000 or Bruker MaXis 4G spectrometer,
both of which were operated in high resolution positive ion
electrospray mode. Samples were dissolved and diluted
to the required concentration in HPLC grade acetonitrile
or methanol.
Fig. 7 The trinuclear discrete assembly of complex (8). All hydrogen atoms have
been omitted for clarity.
Preparation of ligands
However, the analogous complex (8), [Ag3(3)(OTf)2](OTf),
prepared from silver triflate and (3) is once again a discrete
species. Complex (8) crystallises in the monoclinic space
group P21/c. The asymmetric unit contains one full molecule
of (3), three silver atoms, two coordinated and one non-
coordinated triflate counterion, as shown in Fig. 7. The non-
coordinated triflate is disordered over two sites with 57%
dominant position occupancy. Thus, this complex is a dis-
crete M3L species that uses all nine coordination sites avail-
able within the ligand.
The view shown in Fig. 7 serves to emphasise that the top
half of this complex is remarkably similar to the M2L com-
plex (6) formed from the six armed pyrimidine ligand (2) in
which two silver atoms are gathered together by four allyl
arms on the same face of the ligand and two ring nitrogens,
with capping by a coordinated triflate. However, in complex
(6) the remaining two allyl arms remained uncoordinated on
the opposite face of the ligand. In complex (8) these arms
coordinate to a third silver (Ag3), facilitated by the presence
of the extra nitrogen (N2) in the ring, which coordinates to
this third silver.
Preparation of 2,4-bis(diallylamino)-6-chloro-1,3,5-triazine
(1). A mixture of cyanuric chloride (1.84 g, 10 mmol) and N,
N-diisopropylethylamine (DIPEA) (3.3 ml, 20 mmol) was
stirred in dry THF (60 ml) at 0 °C. Diallylamine (2.5 ml,
20 mmol) was added to this solution and stirred for 2 hours
at this temperature. The solution was then stirred at room
temperature for 2 hours and then refluxed for 48 hours. The
reaction was cooled to room temperature and the crystalline
salt of DIPEA filtered off using a glass sintered filter funnel.
Concentrating the filtrate in vacuo gave a brown oily liquid.
Purification of the crude product with silica gel column
chromatography using petroleum ether gave (1) as a light
1
yellow oily liquid (2.20 g, 72%). H N.M.R. (300MHz, CDCl3):
δ 4.10 (4H, d, J = 5.7 Hz, H3), 4.17 (4H, d, J = 5.7 Hz, H3),
5.10–5.17 (8H, m, H5), 5.72–5.85 (4H, m, H4). 13C N.M.R.
(75MHz, CDCl3): δ 48.74, 48.85 C3, 117.33, 117.50 C5, 133.19,
133.57 C4, 165.06 C2, 169.73 C1. IR (cm−1) 3080, 3010, 2924,
2855, 2526, 2326, 1850, 1642, 1563, 1494, 1414, 1314, 1254,
1237, 1195, 1171, 1110, 1044, 993, 969, 923, 850, 802, 737,
686. ESI-MS: found MNa+ = 328.1307; C15H20ClN5Na requires
MNa+ = 328.1299.
The three silver atoms are four-coordinate with τ4 values
of 0.73, 0.72 and 0.80 for Ag1, Ag2 and Ag3, respectively.
The triply bridging ligand separates silver atoms with the
following distances: Ag1–Ag2 4.913 Å, Ag1–Ag3 6.529 Å and
Ag2–Ag3 6.477 Å. Again the ring nitrogens are highly
pyramidalised with α angles of 51.5°, 49.1° and 54.6° for N1,
N2 and N3, respectively.
Experimental section
General
Preparation of 2,4,6-tris(diallylamino)pyrimidine (2). A
mixture of 2,4,6-triaminopyrimidine (0.63 g, 5 mmol) and
NaH (0.72 g, 30 mmol) was stirred in dry THF (50 ml) at
0 °C. Allyl bromide (2.61 ml, 30 mmol) was added dropwise
to the mixture, which was then refluxed for a week. The
reaction was cooled to room temperature and NaH was
quenched with 30 ml of 1 M aqueous NH4Cl solution. The
organic layer was extracted with 3 × 30 ml of diethyl ether.
Unless otherwise specified, all reagents and starting mate-
rials were reagent grade, purchased from standard suppliers
and used as received. Where anhydrous solvents were
required, the HPLC-grade solvent was either distilled from
standard drying agents or dried by passing over a sealed col-
umn of activated alumina. Melting points were recorded on
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The ethereal extract was washed with water, brine and dried
over MgSO4. Evaporation under reduced pressure gave an
impure yellow oily liquid. Purification of the crude product
with silica gel column chromatography using 5 : 95 ethyl
acetate : petroleum ether gave (2) as a light yellow oily liquid
temperature for 2 hours and then refluxed for 48 hours. The
reaction was cooled to room temperature and the crystalline
salt of DIPEA filtered off using a glass sintered filter funnel.
Concentrating the filtrate in vacuo gave a brown oily liquid.
Purification of the crude product with silica gel column
chromatography using petroleum ether gave (3) as a light
1
(1.78 g, 97%). H N.M.R. (500MHz, CDCl3): δ 4.01 (8H, d, J =
1
5.4 Hz, H7), 4.17 (4H, d, J = 6.0 Hz, H3), 4.94 (1H, s, H6),
5.06–5.16 (12H, m, H1,H9), 5.77–5.95 (6H, m, H2,H8). 13C N.
M.R. (126MHz, CDCl3): δ 49.21 C3, 50.10 C7, 72.27 C6, 115.77
C1, 116.21 C9, 134.92 C8, 136.11 C2, 160.76 C4, 163.55 C5. IR
(cm−1) 3077, 3004, 2952, 2924, 2854, 1836, 1640, 1563, 1468,
1408, 1376, 1340, 1317, 1286, 1265, 1210, 1144, 1113, 994,
963, 916, 787. ESI-MS: found MH+ = 366.2662; C22H32N5
requires MH+ = 366.2658.
yellow oily liquid (0.518 g, 28%). H N.M.R. (300MHz, CDCl3):
δ 4.13 (12H, d, J = 5.9 Hz, H2), 5.09 (6H, dd, J = 10.2, 1.6 Hz,
H4), 5.15 (6H, dd, J = 17.1, 1.6 Hz, H4′), 5.78–5.91 (6H, m,
H3). 13C N.M.R. (126MHz, CDCl3): δ 48.58 C2, 116.35 C4,
135.15 C3, 165.58 C1. IR (cm−1) 3077, 2980, 2919, 1839, 1640,
1538, 1483, 1411, 1315, 1266, 1199, 995, 918, 808. ESI-MS:
found MNa+
389.2424.
= =
389.2427; C21H30N6Na requires MNa+
Preparation of complexes
Preparation of 2,4,6-tris(diallylamino)-1,3,5-triazine (3). A
mixture of cyanuric chloride (0.922 g, 5 mmol) and N,
N-diisopropylethylamine (DIPEA) (2.5 ml, 15 mmol) was
stirred in dry THF (60 ml) at 0 °C. Diallylamine (1.8 ml,
15 mmol) was added to this solution and stirred for 2 hours
at this temperature. The solution was then stirred at room
Complexes (4) and (5). 2,4-Bis(diallylamino)-6-chloro-1,3,5-
triazine (1) (0.0306 g, 0.1 mmol) dissolved in 1 ml acetone was
added to a solution of silver(I) perchlorate (0.0415 g, 0.2 mmol)
in acetone, which produced a white precipitate instantaneously.
The precipitate was dissolved in a mixture of THF, water and
Table 2 X-ray experimental details
Complex
(4)
(5)
(6)
(7)
(8)
Empirical formula
Formula weight
Temperature/K
C18H28N5O10Cl3Ag2 C17H20N5O6F6S2ClAg2 C24H31N5O6F6S2Ag2 C21H30Ag2Cl2N6O8 C24H30N6O9F9S3Ag3
796.54
114
819.69
114(2)
879.4
112.15
781.15
117.15
1137.33
114.15
Crystal system
Space group
Triclinic
P1
Trigonal
R3
Monoclinic
P21/c
Orthorhombic
P212121
Monoclinic
P21/c
¯
¯
Unit cell dimensions: a/Å
b/Å
c/Å
α/°
10.9576(4)
12.0044(4)
12.1220(4)
65.317(2)
70.029(2)
76.155(2)
1352.96(8)
2
1.955
1.804
792
0.45 × 0.26 × 0.20
5.16 to 50.1°
25396
41.519(6)
41.519(6)
9.1478(18)
90
90
120
13657(4)
18
1.794
1.591
7236
12.4040(4)
22.1684(8)
23.4044(8)
90
97.655(2)
90
6378.3(4)
8
1.832
1.44
3504
0.45 × 0.40 × 0.38
3.32 to 51.44°
127348
10.4069(2)
13.8557(4)
37.5419(10)
90
90
90
5413.4(2)
8
1.917
1.702
3120
15.8670(7)
12.8111(5)
18.0525(8)
90
93.503(2)
90
3662.7(3)
4
2.062
1.861
2232
0.40 × 0.29 × 0.07
4.52 to 50.1°
68271
β/°
γ/°
Volume/Å3
Z
Density (calculated) Mg m−3
Absorption coefficient mm−1
F(000)
Crystal size mm−3
θ range for data collection (°)
Reflections collected
0.30 × 0.12 × 0.06
4.6 to 50.1°
13776
0.48 × 0.30 × 0.14
4.48 to 50.1°
103327
Independent reflections [R(int)] 4793[0.0474]
5354[0.0418]
99.9
12139[0.0564]
99.8
9594[0.0660]
99.9
6487[0.0825]
99.8
Completeness %
100
Data/restraints/parameters
Goodness-of-fit on F2
Final R1 indices [I > 2σ(I)]
4793/2/350
1.054
5354/0/352
1.046
12139/0/816
1.022
9594/0/703
1.132
6487/30/533
0.97
R1 = 0.0313
wR2 = 0.0785
R1 = 0.0408
wR2 = 0.0817
1.20/−0.90
R1 = 0.0453
wR2 = 0.1406
R1 = 0.0508
wR2 = 0.1463
1.93/−0.73
R1 = 0.0474
wR2 = 0.1183
R1 = 0.0656
wR2 = 0.1307
2.41/−1.80
R1 = 0.0370
wR2 = 0.0897
R1 = 0.041
wR2 = 0.0919
2.44/−2.75
R1 = 0.0320
wR2 = 0.0636
R1 = 0.0518
wR2 = 0.0681
0.75/−0.61
Final R indices [all data]
Largest diff. peak/hole/e Å−3
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acetone. Slow evaporation of the solvent over a period of time
resulted in the isolation of colourless crystals of (4) suitable for
single crystal X-ray structure analysis. Yield 0.0105 g, 15%. M.p.
259–261 °C (dec). IR (cm−1) 3078, 3010, 2981, 2924, 1708, 1643,
1604, 1562, 1497, 1420, 1317, 1238, 1099, 970, 922, 841, 802,
627. Elem. anal. found: C, 25.89; H, 2.83; N, 9.22. Calc. for
C15H20N5Cl.2AgClO4·1/2CH3COCH3·1/2H2O: C, 26.13; H, 3.19; N,
9.23. Analogous reaction with silver triflate gave complex (5) in
56% yield. M.p. 128–130 °C. IR (cm−1) 3701, 3079, 3010, 2982,
2924, 1718, 1642, 1608, 1560, 1539, 1497, 1424, 1341, 1282,
1252, 1235, 1174, 1103, 1032, 970, 947, 921, 852, 803, 656, 639,
574, 517.
Complex (6). 2,4,6-Tris(diallylamino)pyrimidine (2) (0.0366 g,
0.1 mmol) was dissolved in 1 ml dichloromethane and was
added to a solution of silver(I) triflate (0.0771 g, 0.3 mmol) in
1 ml acetone. The solution was left in darkness at room
temperature and diethyl ether was allowed to diffuse into the
solution. This enabled the isolation of colourless crystals
suitable for single crystal X-ray analysis. Yield 0.0495 g, 56%.
M.p. 128–130 °C. IR (cm−1) 3480, 3078, 2924, 2854, 1731, 1640,
1563, 1468, 1409, 1356, 1253, 1208, 1174, 1051, 993, 917, 850,
787, 767, 658, 637, 578, 521. Elem. anal. found: C, 35.01,
H, 3.95; N, 7.67. Calc. for C22H31N5·2AgSO3CF3·CH3COCH3:
C, 34.59; H, 3.98; N, 7.47.
were refined with anisotropic displacement parameters.
Hydrogen atoms were included in calculated positions with
isotropic displacement parameters 1.2 times the isotropic
equivalent of their carrier atoms. Experimental details are
listed in Table 2.
Conclusions
In this study we have shown that ligands containing two or
three diallylamino groups attached to an azine (pyrimidine or
triazine) unit are able to gather together multiple silver atoms
using a combination of both the allyl arms and azine N
donors. Bi-, tri-, tetra- and poly-nuclear complexes were
formed, within which the silver atoms coordinate to highly
pyramidalised azine nitrogens. We are not aware of other
examples of silver(I) complexes of N-heterocyclic ligand that
incorporate such pronounced degrees of pyramidalisation.
Acknowledgements
We thank the University of Canterbury, College of Science,
for a scholarship for SWK and the RSNZ Marsden fund for
generous financial support.
Complex (7). 2,4,6-Tris(diallylamino)-1,3,5-triazine (3)
(0.0635 g, 0.17 mmol) was dissolved in 1 ml acetone and was
added to silver(I) perchlorate (0.1075 g, 0.52 mmol) also
dissolved in 1 ml acetone. The solution was left in darkness
at room temperature and diethyl ether was allowed to diffuse
into the solution. This enabled the isolation of colourless
crystals suitable for single crystal X-ray analysis. Yield 0.0789 g,
59%. M.p. 119–121 °C. IR (cm−1) 3078, 3008, 2925, 1641, 1596,
1536, 1487, 1413, 1363, 1320, 1269, 1199, 1100, 940, 919,
837, 808, 660, 625. Elem. anal. found: C, 32.46; H, 3.76; N,
10.88. Calc. for C21H30N6·2AgClO4: C, 32.29; H, 3.87; N, 10.76.
Complex (8). 2,4,6-Tris(diallylamino)-1,3,5-triazine (3) (0.0367 g,
0.1 mmol) was dissolved in 1 ml acetone and was added to
silver(I) triflate (0.0771 g, 0.3 mmol) also dissolved in 1 ml
acetone. The solution was left in darkness at room
temperature and diethyl ether was allowed to diffuse into the
solution. This led to the isolation of colourless crystals
suitable for single crystal X-ray structure analysis. Yield
0.0752 g, 66%. M.p. 159–161 °C. IR (cm−1) 3482, 3077, 3009,
2980, 2918, 1640, 1536, 1484, 1412, 1314, 1267, 1199, 1114,
1050, 995, 919, 860, 809, 767, 755, 658, 578, 520. Elem. anal.
found: C, 25.75; H, 2.78; N, 7.61. Calc. for C21H30N6·3AgSO3CF3:
C, 25.35; H, 2.66; N, 7.39.
Notes and references
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