Design of bis(acylamino)triazine containing ruthenium-acetylides as self-complementary supramolecular units

Article abstract of DOI:10.1016/j.jorganchem.2010.09.047

A series of systematically varied 'rigid-rod' octahedral ruthenium-acetylide complexes, bearing conjugated bis(acylamino)triazine (DAT) substituents capable of ADAD-DADA pairing, of general formula trans-[(dppe) ₂Ru(Cl)(CC-C₆H_4<

Full text of DOI:10.1016/j.jorganchem.2010.09.047

Journal of Organometallic Chemistry 696 (2011) 670e675
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Design of bis(acylamino)triazine containing rutheniumeacetylides as
self-complementary supramolecular units
,
,
Inès Ouerfelli a b, Rafik Gatri a b, Mohamed Lotfi Efrit b, Neerja Dua a, Johann Perruchon a,
Stéphane Golhen a, Loïc Toupet c, Jean-Luc Fillaut a
,
*
a Sciences Chimiques de Rennes, UMR 6226 CNRS-Université Rennes 1, 35042 Rennes, France
b Laboratoire de Synthèse Organique et Hétérocyclique, Université de Tunis El Manar-B.P. 94 Poste Romena, 1068 Tunis, Tunisie
c Institut de Physique de Rennes - UMR 6251 CNRS, Université Rennes 1, 35042 Rennes cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of systematically varied ’rigid-rod’ octahedral rutheniumeacetylide complexes, bearing conju-
gated bis(acylamino)triazine (DAT) substituents capable of ADADeDADA pairing, of general formula
trans-[(dppe)2Ru(Cl)(C^CeC6H4eDAT(R)2)] (R ¼ Et, i-Pr, t-Bu, n-C5H11) have been synthesized and
thoroughly characterized in solution by 1H NMR and in the solid state. trans-[Ru(eC^CeC6H4eDAT(R)2)2
(dppe)2] (R ¼ n-C5H11) has also been designed to form discrete oligomeric chains in solution.
Ó 2010 Elsevier B.V. All rights reserved.
Received 24 August 2010
Received in revised form
14 September 2010
Accepted 20 September 2010
Available online 25 September 2010
Keywords:
Self-assembly
Hydrogen bond
Ruthenium
Alkynyl
Crystal structure
1. Introduction
The combination of transition metals and hydrogen bonding
interactions has recently become increasingly important in several
Self-assembly is an area of vigorous research activity that has
strongly impacted several facets of Materials Science. It is moti-
vated by the anticipation that careful design of functional molec-
ular systems that self-assemble through the concerted action of
multiple non-covalent interactions will direct the tailoring of
materials with specific physical and chemical properties [1e3].
Being able to design and construct large and complex architectures
from small molecular modules requires a precise knowledge of the
basic structural units that are formed by intermolecular interac-
tions in a reversible and predictable manner [4]. The structural and
functional properties of the final supramolecular assemblies result
from the assembling information stored in the molecular compo-
nents, which are dictated by the interplay of both geometrical and
conformational constraints, and by the presence of complementary
recognition end-groups. Hydrogen bonds are the ideal non-cova-
lent interactions to be used in molecular organization because they
combine directionality with strength, along with a reversible
character, providing access to a vast variety of predictable func-
tional assemblies [5e7].
areas of chemistry because of the specific optical, magnetic and
electronic properties of coordination and organometallic
compounds, and their potential applications in many fields such as
materials, biomedicine, engineering, communications, microelec-
tronics and sensors [8]. One challenging problem in this area is then
learning how to combine hydrogen bonding modules with func-
tional systems to drive molecular organization in predetermined
patterns [9]. An interesting strategy has focused on the design of
pendant ligands which contain specific hydrogen bonding modules
to be involved in intermolecular interactions; the crucial feature of
this strategy is that the metal should preferentially coordinate to
the active site in the pendant ligand, rather than to heteroatoms in
the hydrogen bonding modules. Indeed, many metal carbon bonds
are reactive toward the types of functional groups, such as the
protic groups used as hydrogen bond donors, which are commonly
used in self-assembly and crystal engineering [8]. Very few suitable
synthons have been identified to date but recent approaches by our
group and others show that alkynes are interesting building motifs
for this purpose [10e14]. In particular, alkynes substituted by
nucleobases and by ureaepyrimidinedione constitute valid candi-
dates that allow for the synthesis of transition metal species
capable of acting as supramolecular synthons, both in solution and
* Corresponding author. Tel.: þ33 0 223235952; fax: þ33 0 223236939.
E-mail address: jean-luc.fillaut@univ-rennes1.fr (J.-L. Fillaut).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.09.047

I. Ouerfelli et al. / Journal of Organometallic Chemistry 696 (2011) 670e675
671
R
in the solid state [11,13]. We also illustrated that trans-[(dppe)2Ru
O
N
N
O
(Cl)(C^CeR)] bearing terminal hydrogen bonding receptors can be
used as efficient sensors exhibiting large guest-induced colour
changes due to interactions of anions with these receptors [12].
Our current approach consists on the introduction of diamino-
triazine units as hydrogen bonding modules at the remote end of
trans-[(dppe)2Ru(Cl)(C^CeR)] alkynyleruthenium derivatives.
Metaleacetylide complexes constitute valid candidates in this
context to generate well-defined supramolecular architectures. The
linear and rigid arrangement of atoms in MeC^CeR structure
makes them particularly attractive building blocks for a wide range
of complex architectures and applications in materials chemistry
(electron transfer, nonlinear optics, sensing, etc) due to the efficient
electronic coupling between the metal and the remote groups
NH2
N
NH
N
N
N
(i)
(ii)
Br
Br
C N
Br
NH2
NH
R
(1)
2(a-d)
(iii)
R
R
O
O
N
N
O
NH
N
NH
N
N
N
O
(iv)
H C
C
Me3Si C C
NH
R
NH
R
3(a-d)
4(a-d)
(a)
C2H5
R=
R=
R=
through the p-conjugated path [15,16].
1,3,5-Triazines constitute a family of heterocycles that have been
widely investigated in chemical molecular-recognition studies
[17e22]. For instance, Asadi et al. designed Janus-bases in which
diaminotriazineeuracil self-complementary units are capable of
ADAeDAD pairing [23]. On the other hand, Rotello and coworkers
investigated the modulation of recognition in conjugated bis(acy-
lamino)triazine moieties and flavin via triple hydrogen bonding
formation, demonstrating an efficient electronic communication in
the bis(acylamino)triazine based receptors [24]. Rotello and
coworkers also established that the dimerisation of substituted
bis(acylamino)triazine are determined by the nature of the
substituents [25].
We present herein the synthesis and characterization of orga-
noruthenium complexes bearing conjugated bis(acylamino)
triazine moieties for their ability to form ADAD-DADA pairing. A
structure determination unambiguously demonstrates the forma-
tion of homodimer pairs via quadruple hydrogen bonding forma-
tion. These assemblies have also been thoroughly characterized in
solution by 1H NMR. We thus provide evidence that the accurate
design of the multivalent molecular building blocks allows the
versatile generation of complex and discrete assemblies of rigid-
(b)
(c)
(d)
CH(CH3)2
C(CH3)3
C5H11
R=
Scheme 1. (i) Dicyandiamide (1.3 equiv.), KOH (0.21 equiv.), 2-ethoxyethanol (60 ml),
reflux, 24 h. (ii) acyl chloride (3.8 equiv.), pyridine, reflux, 72 h. (iii) PdCl2(PPh3)2
(0.05 equiv.), CuI (0.1 equiv.), TMSA (3 equiv.), THF (40e60 ml), iPr2NH (25e40 ml),
50 ꢀC, 72 h. (iv) Bu4NF (solution 1 M, 1.5 equiv.), THF (25 ml), H2O (1 ml), r.t, 2 h.
b ¼ 16.2361(9), c ¼ 18.2229(9) Å,
a
¼ 108.311(6),
b
¼ 98.442(4),
g
m
¼ 105.193(6)ꢀ, V ¼ 3378.5(3) Å3, Z ¼ 4,
r
¼ 1.391 g cmꢁ3
,
¼ 4.98 cmꢁ1, F(000) ¼ 1468, T ¼ 110(1) K. The data collection [27]
(2qmax ¼ 54ꢀ, omega scan frames via 0.7ꢀ omega rotation and 15 s
per frame, range HKL:H ꢁ18,17 K ꢁ24,23 L ꢁ20,26) gives 31855
reflections. The data leads to 14249 independent reflections from
which 7878 with I > 2.0s(I). The structure was solved with SIR-97
[28] which reveals the non-hydrogen atoms of the molecule. After
anisotropic refinement, all the hydrogen atoms are found with
a Fourier Difference. The whole structure was refined with SHELXL-
97 [26] by the full-matrix least square techniques use of F2
magnitude; x, y, z, bij for Ru, P, Cl, N, C and O atoms, x, y, z in riding
mode for H atoms; 811 variables and 9147 observations with
rod ruthenium
geometry.
s-acetylides, such as dimers, featuring a controlled
I > 2.0
s
(I); calc w ¼ 1/[
s
2(Fo2) þ (0.038P)2] where P ¼ (Fo2 þ 2F2c)/3
with the resulting R ¼ 0.045, Rw ¼ 0.095 and Sw ¼ 0.864,
Dr < 1.31 e Åꢁ3. Atomic scattering factors were taken from Inter-
national Tables for X-ray crystallography (1992) [29]. The ORTEP
view was realised with PLATON98 [30]. Crystallographic data have
been deposited with the Cambridge Crystallographic Data Centre as
supplementary publication CCDC-646840.
2. Experimental
2.1. Crystallography
Single crystal of 7a was mounted on a Nonius four-circle
diffractometer equipped with a CCD camera and a graphite mon-
ochromated Mo K
a
radiation source (
l
¼ 0.71073 Å) from the
Centre de Diffractométrie (CDFIX), Université de Rennes 1, France.
Data collection was performed at 293(2) K. Compound 7a
(C69H64ClN5O2P4Ru) crystallizes in the monoclinic centrosym-
3. Results and discussion
3.1. Synthesis of rutheniumeacetylide complexes
metric P21/c space group,
a
¼
12.6702(3),
b
¼
24.7937(9),
c ¼ 20.9616(7) Å,
b
¼ 112.228(9)ꢀ, V ¼ 6095.5(3) Å3, Z ¼ 4,
The synthetic methodologies employed for the preparation of
the new ruthenium derivatives have been adapted from previously
reported procedures [31]. Substituted alkynes HeC^CeC6H4eDAT
(R)2 (R ¼ Et, i-Pr, t-Bu, n-C5H11) required for the syntheses of the
alkynyl complexes 6aed were prepared by well-established
organic synthetic procedures from their bromoaromatic precursors
(Scheme 1) [25]. 6-(4-Bromophenyl)-1,3,5-triazine-2,4-diamine 1
was prepared by reaction of commercially available dicyandiamide
in excess with 4-bromobenzonitrile in 2-ethoxyethanol in the
presence of KOH, at reflux for 24 h. The presence of bromine allows
the introduction of an acetylenic unit in a further step. After puri-
fication, the product was isolated as a brown powder (89%) the
solubility of which is limited to highly polar solvents (DMSO).
Attempts to perform Sonogashira coupling at this stage resulted
in low yields. It readily appeared that the 2,4-diaminotriazine
r
¼ 1.368 g cmꢁ3
, m
¼ 4.56 cmꢁ1, F(000) ¼ 2600. Structure was
solved with SHELXS-97 [26] and refined with SHELXL-97 programs
by full-matrix least squares methods on F2. The refinement of 739
parameters of 13846 unique reflections [7727 observed intensities
I ꢂ 2
s(I)] was performed with anisotropic thermal parameters for
all non-hydrogen atoms. Hydrogen atoms were added to the
structure model on calculated positions. Final residues R1[I ꢂ 2
s
(I)] ¼ 0.0556; wR2 ¼ 0.1142. Crystallographic data have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication CCDCe784980.
Single crystal of 7c (0.18 ꢃ 0.15 ꢃ 0.15 mm) was mounted on an
Oxford Diffraction Xcalibur Saphir 3 diffractometer with graphite
monochromatized Mo K
RuP4Cl3C74H76N15O3, Mr ¼ 1414.70, triclinic, P ꢁ 1, a ¼ 12.8727(7),
a
radiation source (
l
¼ 0.71073 Å).

672
I. Ouerfelli et al. / Journal of Organometallic Chemistry 696 (2011) 670e675
R
yield. The (DAT)-substituted alkynes 4aed were obtained using
O
N
N
O
a slight excess of tetrabutylammonium fluoride in THF at ambient
temperature, as white crystalline products after purification on
silica column (84e87%). These new acetylenes were characterized
by NMR spectroscopy and mass spectrometry.
NH
N
Ph2P PPh2
H
(i)
TfO
H C
C
Cl Ru
C C
Ph2P PPh2
NH
R
O
N
N
R
The reaction of
a
slight excess (e1.2 equiv.) of alkynes
N
N
O
R
N
H
HeC^CeC6H4eDAT(R)2 (R ¼ Et, i-Pr, t-Bu, n-C5H11) 4aed and [cis-
(Cl)(PPh2CH2CH2PPh2)2Ru][TfO] 5 in dichloromethane at room
temperature for 20 h resulted in the formation of intermediate
vinylidene species 6 (Scheme 2) [31]. These reactions were moni-
tored by 31P NMR in order to ensure their completion. Solvent was
removed and the resulting residue was washed with diethyl ether,
affording purple vinylidene species 6aed. Further purification can
be achieved by diphasic recrystallisation from dichloromethane/
pentane (1:2) to give crystals of vinylidene complexes, but 6aed
were generally clean enough to be used in the next step. These
vinylidenes were then dissolved in CH2Cl2 before being deproto-
nated using dry potassium carbonate (methylene chloride, room
temperature, 16 h). The resulting alkynyl compounds were washed
with water before being purified by diphasic recrystallisation from
dichloromethane/pentane (1:2) as crystalline orange powders in
approximately 58e65% yields (based on 5). All the spectroscopic
data of compounds 7aed are consistent with their proposed
structures.
4(a-d)
6(a-d)
H
(iii)
(ii)
R
H N
R
R
O
O
N
N
O
O
N H
N
N H
N
Ph2P PPh2
C Ru C C
Ph2P PPh2
Ph2P PPh2
Cl Ru
Ph2P PPh2
N
N
O
N
N
O
N
C
C
C
H N
R
N H
R
N H
R
8d
7(a-d)
C2H5
(a)
R=
(b) R=
CH(CH3)2
C(CH3)3
C5H11
(c)
(d)
R=
R=
Scheme 2. (i) [cis-(Cl)(PPh2CH2CH2PPh2)2Ru] [TfO] 5 (1.2 equiv.), CH2Cl2 (30e50 ml),
r.t., 20 h.; (ii) K2CO3 (6 equiv.), CH2Cl2 (30e50 ml), r.t., 16 h. (iii) 4d (1.0 equiv.), NEt3
(3 equiv.), KPF6 (3 equiv.), CH2Cl2 (30 ml), 35 ꢀC, 3 days.
Several attempts to synthesize the bis alkynyl compounds 8a
and b from the parent vinylidene species 6a and b were unsuc-
cessful, even in the presence of large excess of alkynes 4a and b.
Monitoring of the reaction by 31P NMR indicated that the
complexes 8a and b formed in small amounts but precipitated
during the course of the procedure. Completion of the formation
was never observed and separation from complexes 7a and b, also
formed during this step by deprotonation of the parent complexes
6a and b revealed not possible. We thus decided to synthesize 8d
bearing longer alkyl chains. The reaction of an excess (w2.1 equiv.)
derivatives were scarcely soluble in solvents of low polarity. Taking
into consideration the solubility of these components in low polar
solvent such as CH2Cl2 or CHCl3 as a crucial factor when designing
self-assembled structures, acylation of 1 was achieved by treating
with an excess of corresponding carboxylic acid chloride in dry
pyridine at reflux for 72 h. Purification by silica column afforded
2aed as white crystalline solids (77e79%). As expected the solu-
bility of these compounds is good, even in low polar solvent such as
chloroform (Scheme 1).
of HeC^CeC6H4eDAT(R)2 (R
(PPh2CH2CH2PPh2)2Ru][TfO]
¼
n-C5H11
) 4d and [cis-(Cl)
5
in dichloromethane at room
3aed were prepared by the Sonogashira coupling of 2aed with
(trimethylsilyl)acetylene in the presence of PdCl2(PPh3)2 and CuI.
The reaction was carried out in a 1:1mixture of THF and diisopro-
pylamine at 50 ꢀC for 72 h. Further purification by column chro-
matography on silica afforded 3aed as white powders in 80e85%
temperature for 5 h resulted in the formation of intermediate
vinylidene species 6d (Scheme 2) as depicted by 31P NMR. To this
solution were successively added KPF6 (3 equiv.) and NEt3
(3 equiv.), under inert atmosphere. The mixture was allowed to stir
for 72 h at 35 ꢀC to ensure the completion of the reaction as
Fig. 1. Variable-concentration (mmol Lꢁ1 1H NMR study of 7a (left) and 7c (right) in CDCl3 at 233 K.
)

I. Ouerfelli et al. / Journal of Organometallic Chemistry 696 (2011) 670e675
673
Table 1
9.60
9.40
9.20
9.00
8.80
8.60
8.40
8.20
8.00
7.80
Bond lengths [Å] and angles [ꢀ] for 7c.
Ru(1)eC(53)
Ru(1)eP(4)
Ru(1)eP(2)
O(1)eC(64)
N(1)eC(62)
N(2)eC(62)
N(3)eC(63)
N(4)eC(62)
N(4)eH(4)
N(5)eC(69)
C(53)eC(54)
C(55)eC(56)
C(56)eC(57)
C(58)eC(59)
C(59)eC(60)
C(65)eC(68)
1.996(4)
2.3446(10)
2.3872(10)
1.216(4)
1.339(4)
1.314(4)
1.323(4)
1.390(4)
0.8800
1.382(5)
1.204(5)
1.411(5)
1.371(5)
1.399(5)
1.373(5)
1.513(5)
1.551(5)
84.63(10)
98.20(10)
175.41(10)
171.4(4)
113.6(3)
128.5(3)
115.7
Ru(1)eP(3)
2.3425(10)
Ru(1)eP(1)
Ru(1)eCl(1)
O(2)eC(69)
N(1)eC(61)
N(2)eC(63)
N(3)eC(61)
N(4)eC(64)
N(5)eC(63)
2.3746(10)
2.4832(9)
1.231(5)
1.339(4)
1.344(5)
1.347(4)
1.388(5)
1.372(4)
0.8800
N(5)eH(5)
C(54)eC(55)
C(55)eC(60)
C(57)eC(58)
C(58)eC(61)
C(64)eC(65)
C(65)eC(67)
1.442(5)
1.415(4)
1.398(5)
1.476(5)
1.531(5)
1.527(6)
e
7a
7b
7c
7d
8d
C(65)eC(66)
e
C(53)eRu(1)eP(3)
C(53)eRu(1)eP(1)
C(53)eRu(1)eCl(1)
C(53)eC(54)eC(55)
C(62)eN(2)eC(63)
C(62)eN(4)eC(64)
C(64)eN(4)eH(4)
C(63)eN(5)eH(5)
N(3)eC(61)eN(1)
N(1)eC(61)eC(58)
N(2)eC(62)eN(4)
N(3)eC(63)eN(2)
N(2)eC(63)eN(5)
O(1)eC(64)eC(65)
O(2)eC(69)eN(5)
C(53)eRu(1)eP(4)
C(53)eRu(1)eP(2)
C(54)eC(53)eRu(1)
C(62)eN(1)eC(61)
C(63)eN(3)eC(61)
C(62)eN(4)eH(4)
C(63)eN(5)eC(69)
C(69)eN(5)eH(5)
N(3)eC(61)eC(58)
N(2)eC(62)eN(1)
N(1)eC(62)eN(4)
N(3)eC(63)eN(5)
O(1)eC(64)eN(4)
N(4)eC(64)eC(65)
O(2)eC(69)eC(70)
85.56(10)
97.65(10)
176.1(3)
113.9(3)
114.1(3)
115.7
0
20
40
60
mMol.L-1
Fig. 2. Chemical shifts of 1H resonances of the amido NH groups for 7aed and 8d at
various concentrations in CDCl3 at 233 K.
130.2(3)
114.9
114.9
125.1(3)
118.0(3)
118.9(3)
126.4(3)
112.3(3)
120.7(4)
122.3(4)
116.9(3)
126.9(3)
114.1(3)
121.3(3)
123.2(3)
116.0(3)
123.5(4)
depicted by 31P NMR (
d
CDCl3 ¼ 54.44 ppm). This compound was
tentatively purified by crystallisation from dichloromethane/
pentane, giving rise to amorphous powders of 8d. All the spectro-
scopic data of compound 8d are consistent with the proposed
structure.
3.2. Solution-state 1H NMR titrations
determined the Kass of the corresponding homodimer pairs [25].
The Kass of the homodimer 7ae7a in CDCl3 was calculated to be
approximately 65 ꢄ 5 Mꢁ1. This value is larger than that of the
homodimer pair 7be7b (ca. 50 ꢄ 5 Mꢁ1) and notably larger than
that of 7ce7c (ca. 15 ꢄ 5 Mꢁ1). Similar tendencies can be observed
for the organic analogues 2aec, but the electron withdrawing effect
of the bromo substituant results in a lowering of the shifting of the
protons of the amido NH groups. The Kass of the 2e2 homodimers
are significantly lower than that of the 7e7 organometallic dimers
(30 ꢄ 5 Mꢁ1 for 2a). At a first glance, the presence of the strong
electron donating trans-[(dppe)2Ru(Cl)(C^Ce)] moiety would
enhance the hydrogen bond accepting capability of the triazine ring
nitrogen.
1H NMR dilution experiments in CDCl3 were carried out for the
(DAT)-substituted rutheniumeacetylide complexes 7aed and 8d.
The intermolecular hydrogen bonding is evidenced by the fact that
the signals of both amide protons appear in the downfield area.
7a,b and d revealed important downfield shifting of the protons of
the two amido NH groups, when concentration was increased
(Fig. 1 left: 7a). Conversely, shifting of the protons of the two amido
NH groups, when concentration of 7c increased was much smaller
(Fig. 1 right). Using these 1H NMR dilution experiments, we
Fig. 4. Packing of compound 7c at 110 K, showing the H-bonds, selected bond lengths
and angles are given in Table 1.
Fig. 3. Variable-concentration 1H NMR study of 8d in CDCl3 at 233 K.

674
I. Ouerfelli et al. / Journal of Organometallic Chemistry 696 (2011) 670e675
Fig. 5. Packing of compound 7a at 293 K, showing the H-bond i: 2 ꢁ x, ꢁy, 2 ꢁ z; Table 2 gives selected bond lengths and angles.
Steric effects also strongly affect the relative stability of the
in this heterocyclic ring fall within the range of those previously
homodimers in solution: the calculated Kass for 7c is the smallest
value for all the series. A rationale for this behavior may be traced
back to the greater hindrance between the pivaloyl group and the
triazine ring that would result in a less planar arrangement of
donor (D) and acceptor (A) in this complex.
Similarly, the chemical shift of the amido NH hydrogens in 7d
and 8d moved downfield with higher concentrations, suggesting
that these hydrogens are involved in strong hydrogen bonding (see
Figs. 2 and 3). The Kass of the 7de7d and 8de8d were calculated to
be approximately 70 and 75 ꢄ 5 Mꢁ1, in the same range as 7a. The
differences in the shifts in 7a and 7d or 8d may be attributed to
differences in the aggregation capacity of these derivatives. These
data suggest that the complex 8d is capable of forming discrete
oligomeric chains in solution, due to the hydrogen bond supported
dimerisation of the diamidotriazine units.
reported for comparable fragments [36,37].
Orange crystals of 7a were obtained upon slow diffusion of
a dichloromethaneepentane solution and investigated by X-ray
crystallography. A plot of the complex is shown in Fig. 5 while
significant bond parameters are given in Table 2. Most bond lengths
and angles about the CleRueC(53)eC(54)eC(55) units in this
structure are close to bond lengths and angles in 7c. Meanwhile,
comparing the structures in 7a and 7c, the RueC(53) bond length of
1.988(4) Å is short with respect to that observed in 7c (1.997(3) Å)
while the C(53)eC(54) bond of 1.221(5) Å is longer than a typical CC
triple bond (average value 1.189 Å) and slightly longer than that in 7c
(1.205(4) Å. Finally, the C(54)eC(55) distance of 1.424(5) Å shows
somecharacterof a double bond. Similarly, the C(58)eC(61) distance
of 1.456(5) Å in 7a is short with respect to the C(58)eC(61) distance
of 1.478(4) Å in 7c. These differences between adjacent CC bonds
could arise from a stronger push-pull character in 7a, compared to
7c, due to the formation of hydrogen bonds that enhances the
electron withdrawing character of the triazine ring. Indeed, an
3.3. Solid state structure of complexes 7a and 7c
To obtain unambiguous information about the hydrogen
bonding in these systems, crystal structures of crystals of 7a and 7c
were determined by X-ray diffraction. Single crystals suitable for X-
ray structure determination could only be obtained by very slow
Table 2
Selected bond lengths [Å] and angles [ꢀ] for 7a.
RueP(1)
RueP(3)
RueCl
O(1)eC(64)
N(1)eC(63)
N(2)eC(62)
N(3)eC(62)
N(4)eC(62)
N(4)eH(4)
N(5)eC(63)
N(5)eH(5)
C(54)eC(55)
C(55)eC(56)
C(57)eC(58)
C(58)eC(61)
C(64)eC(65)
C(53)eRueP(1)
C(53)eRueP(3)
C(53)eRueCl(1)
C(53)eC(54)eC(55)
C(62)eN(2)eC(63)
C(62)eN(4)eC(67)
N(1)eC(61)eN(3)
N(3)eC(61)eC(58)
N(2)eC(62)eN(4)
N(3)eC(62)eN(2)
N(2)eC(63)eN(5)
O(1)eC(64)eC(65)
O(2)eC(67)eN(4)
2.3460(11)
2.3994(11)
2.4811(10)
1.218(5)
1.332(5)
1.347(5)
1.327(5)
1.377(5)
0.860
RueP(2)
RueP(4)
RueC(53)
O(2)eC(67)
N(1)eC(61)
N(2)eC(63)
N(3)eC(61)
N(4)eC(67)
2.3551(11)
2.3870(11)
1.988(4)
1.191(5)
1.342(5)
1.334(5)
1.339(5)
1.382(5)
1.386(4)
1.378(5)
1.221(5)
1.399(6)
1.383(6)
1.395(5)
1.372(5)
evaporation of
a pentaneedichloromethane solution mixture
(ca. 1/2) of 7c, into the air, at room temperature.
Details of the X-ray analysis are given in Experimental section
(Table S2). Selected bond lengths and angles are listed in Table 1.
A plot of the complex is shown in Fig. 4. The solid state structure
revealed a monomeric structure, in which the triazine unit of the
monomer was hydrogen bonded to a water molecule. One of the
amido groups in 7c is rotated in the direction of the metal centre
which presumably results in better stabilisation due to interaction
between the NH group and the ring nitrogen atom. We attribute
this result to the large size of the butyl group connected to the
diacyl diaminotriazine unit, which disfavours the linear self-asso-
ciating mode and facilitates the organization of the receptor for
foreign molecules. Most bond lengths and angles about the
CleRueC(53)eC(2)eC(3) units in this structure are classical. For
instance, the CleRu (2.4832(9) Å), RueC(53) (1.996(4) Å), C(53)eC
(54) (1.204(5) Å) and C(54)eC(55) (1.442(5) Å) data for this
complex fall within the range of those previously reported for
N(5)eC(63)
1.386(5)
0.860
N(5)eC(64)
C(53)eC(54)
1.424(5)
1.379(5)
1.384(6)
1.456(5)
1.491(5)
83.74 (11)
97.22 (11)
174.83(11)
174.6(5)
112.7(3)
127.7(4)
124.5(4)
117.3(4)
115.7(3)
126.4(4)
114.6(3)
120.3(4)
123.1(4)
C(55)eC(60)
C(56)eC(57)
C(58)eC(59)
C(59)eC(60)
e
e
C(53)eRueP(2)
C(53)eRueP(4)
C(54)eC(53)eRu(1)
C(61)eN(1)eC(63)
C(61)eN(3)eC(62)
C(63)eN(5)eC(64)
N(1)eC(61)eC(58)
N(1)eC(63)eN(2)
N(1)eC(63)eN(5)
N(3)eC(62)eN(4)
O(1)eC(64)eN(5)
N(4)eC(67)eC(68)
O(2)eC(67)eC(68)
84.36(11)
100.44 (11)
175.2(4)
114.5(3)
115.0(4)
131.2(3)
118.2(3)
127.0(4)
118.4(3)
117.9(4)
117.3(4)
114.1(4)
122.9(4)
related
octahedral
trans-bis(bidentate
phosphine)ruth-
eniumealkynyl complexes [12,32e35]. The dihedral angle formed
by the planes of the phenyl and triazine rings is close to coplanarity
(10.0 ꢄ 0.1ꢀ) confirming the conjugated pathway from one part of
this model to the other (see also Table 1). Bond lengths and angles

I. Ouerfelli et al. / Journal of Organometallic Chemistry 696 (2011) 670e675
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Acknowledgements
The authors acknowledge the support of the CNRS and DGRSRT
under Grant 08/R 12-06
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