Synthesis of heteroleptic pyrrolide/bipyridyl complexes of ruthenium(II)

Article abstract of DOI:10.1139/v2012-045

The synthesis and characterization of the first heteroleptic pyrrolide/2,2′-bipyridyl complexes of ruthenium(II) are reported. Pyrroles substituted at the 2-position with X = O functionality react with Ru(bipy) ₂Cl₂·2H₂O t

Full text of DOI:10.1139/v2012-045

693
Synthesis of heteroleptic pyrrolide/bipyridyl
complexes of ruthenium(II)
Travis Lundrigan, Carla L.M. Jackson, Md. Imam Uddin, Lloyd A. Tucker,
Adeeb Al-Sheikh Ali, Anthony Linden, T. Stanley Cameron, and Alison Thompson
Abstract: The synthesis and characterization of the first heteroleptic pyrrolide/2,2’-bipyridyl complexes of ruthenium(II) are
reported. Pyrroles substituted at the 2-position with X = O functionality react with Ru(bipy)2Cl2·2H2O to form complexes in
which the pyrrolide ligands chelate to Ru(II). The library of pyrroles includes 2-formyl, 2-keto, 2-carboxylato, 2-sulfinyl,
and 2-sulfonyl derivatives.
Key words: ruthenium complexation, formyl pyrrole, keto pyrrole, chelation.
Résumé : On a effectué la synthèse et caractérisé les premiers complexes hétéroleptiques pyrrolidure/2,2’-bipyridyle du ru-
thénium(II). Les pyrroles substitués en position 2 par une fonctionnalité X = O réagissent avec le Ru(bipy)2Cl2·2H2O pour
former des complexes dans lesquels les ligands pyrrolidures se chélatent au Ru(II). La bibliothèque de pyrroles comprend
les dérivés 2-formyle, 2-céto, 2-carboxylato, 2-sulfinyle et 2-sulfonyle.
Mots‐clés : complexation du ruthénium, formylpyrrole, cétopyrrole, chélation.
[Traduit par la Rédaction]
few examples reported with ruthenium(II).17–20 For example,18
a pyrrolide–ruthenium complex has been observed through
the use of a bidentate a-substituted pyrrole, producing N,O-
coordinated pyrrolide–ruthenium complexes as models for
catalytic intermediates in the Murai coupling reaction (A,
Fig. 1). These results lead us to postulate that there may be
increased success with pyrrolide–metal complexation using
bidentate a-substituted pyrroles. Furthermore, chelation facili-
tates the coordination of pyrrolyldipyrrinato ligands to tin(IV)
complexes that feature a pyrrolide and a dipyrrinato unit.21
Coordination of pyridylpyrrolides to K, Cu, Ag, Au, and Rh
has recently been reported.22 Bidentate coordination of pyr-
role to ruthenium has also been accomplished through the re-
action of TpRu(CO)(NCMe)(Me) with pyrrole, which results
in the formation of product B.19 The product contains an N-
pyrrolide ligand with a coordinating pendant imine that arose
from addition to the previously coordinated acetonitrile unit,
presumably via metal-mediated N–H/C–H activation of the pyr-
role, accompanied by the release of methane. Interestingly, lith-
ium pyrrolide displaced triflate from TpRu(CO)(NCMe)(OTf)
to give TpRu(N-pyrrolide)(CO)(NCMe), without C–H activation,
Introduction
The chemistry of the cyclopentadienyl unit as a ligand in
transition metal chemistry is well-established.1,2 However,
the ability of isoelectronic and geometrically comparable pyr-
rolide ligands to coordinate to transition-metal centres is sig-
nificantly underdeveloped.3,4 It was frequently believed that
pyrrolide–metal complexes were intrinsically unstable, based
on attempts to prepare complexes of various transition metals
using sodium pyrrolide that met only with disappointment.5
Subsequently, p-cyclopentadieneyl-p-pyrrolyliron complexes
(azaferrocenes) were discovered5,6 following the synthesis of
p-pyrrolide manganese tricarbonyl, apparently the first exam-
ple of a pyrrolide–metal complex.7 Numerous pyrrole-based
metal complexes have since been reported, but the ligands
are often cyclopyrrolic8 (macrocycles containing pyrrole
units), particularly tetrapyrrolic,9 with limited examples of
simple pyrrolic systems.
Pyrrolides may coordinate in several alternative modes: p
coordination (h5), involving the entire p system; an N-s
mode (h1); and a C-s mode (h1). Most pyrrolide transition-
metal complexes correspond to the N-s h1 mode. However,
there are also examples of h2 coordination to rhenium, tung-
sten, and osmium,10,11 as well as examples of h1 complexa-
tion to rhenium through the 2-position of pyrrole.12,13
akin to reactions previously reported for rhenium.12,13
A
similar approach has been utilized to prepare ruthenium
complexes of azoferrocenes that, of course, feature a pyrro-
lide ligand.18
Although pyrrolide complexes of transition metals such as
rhenium14,15 and molybdenum16 have been reported, there are
Within the context of dipyrrinato complexes,23 dipyrrinato-
Received 25 April 2012. Accepted 4 June 2012. Published at www.nrcresearchpress.com/cjc on XX July 2012.
T. Lundrigan, C.L.M. Jackson, M.I. Uddin, L.A. Tucker, T.S. Cameron, and A. Thompson. Department of Chemistry, Dalhousie
University, PO BOX 15000, Halifax, NS B3H 4R2, Canada.
A.A.-S. Ali. Department of Chemistry, Dalhousie University, PO BOX 15000, Halifax, NS B3H 4R2, Canada; Chemistry Department,
Taibah University, Almadinah Almunawarah, P.O. Box 30002, Saudi Arabia.
A. Linden. Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Corresponding author: Alison Thompson (e-mail: alison.thompson@dal.ca).
Can. J. Chem. 90: 693–700 (2012)
doi:10.1139/V2012-045
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Can. J. Chem. Vol. 90, 2012
Scheme 1. Synthetic route to 2-formyl and 2-keto pyrrolide – ruthenium(II) complexes.
Table 1. The optimization of time and temperature for the for-
mation of complex 2a.
Fig. 1. Literature examples of bidentate pyrrolide–ruthenium(II)
complexes.
Trial
Time (min)
Temp. (°C)
100
100
125
100
Isolated yield (%)
1
2
3
4
5
30
60
60
90
90
20
25
93
54
45
125
timized for the microwave system (Table 1), using pyrrole
1a. The literature procedure24 suggests a reaction time of
35 min at 100 °C for complexation of dipyrrinato ligands to
ruthenium(II), but optimum reaction conditions for the for-
mation of pyrrolide–ruthenium(II) complexes were found to
be 60 min at 125 °C.
The optimized conditions were then applied to 2-formyl
pyrroles (Table 2, entries 1–6) and 2-keto (Table 2, entries
7–9) pyrroles 1b–1i, with high yields achieved throughout.
Various alkyl groups were used as substituents around the
pyrrole ring, with one example containing a halogen substitu-
ent. Fully substituted pyrroles (1a, 1b, 1f–1g, and 1i) were
tolerated well by the reaction, as were pyrroles featuring un-
substituted positions (1c–1e and 1h). In most cases, small
amounts of pyrrolic starting material remained after the reac-
tion, but these were easily removed upon work-up and purifi-
cation as described previously.
bound ruthenium(II) complexes24 have been reported re-
cently, with two bipyridyl units further supporting the metal
centre. Ruthenium complexes bearing bipyridyl ligands are
very common, and are useful because of their photochemical
and photophysical properties.25 We herein report the synthe-
sis and properties of the first heteroleptic pyrrolide 2,2’-bi-
pyridyl (bipy) complexes of ruthenium(II).
Results and discussion
2-Formyl and 2-keto pyrroles
Cognisant of the dipyrrinato scaffold, whereby anionic
pyrrolide and neutral azafulvene (imine) units act synergisti-
cally to chelate ruthenium(II) in bis(2,2’-bipy) complexes,24
we first investigated 2-formyl and 2-keto pyrroles (Scheme 1)
as potential sources of pyrrolide ligands. Pyrrole 1a, fully
substituted around the pyrrole ring and bearing a formal
group in the 2-position, served as our first candidate. Follow-
ing a modified literature procedure,24 1.1 equiv of the pyrrole
were reacted with [Ru(bipy)2Cl2] in ethylene glycol under
microwave irradiation in the presence of triethyl amine. The
resulting reaction mixture was then added to a solution of
2-Carboxylate pyrroles
We then pursued complexation reactions with pyrroles
containing a carboxylate functionality in the 2-position
(Scheme 2), as the flanking chelating moiety appears to be
the key to success. Initial attempts garnered little success
(Table 3, entries 1 and 2), presumably via destabilization of
the Ru–O bond courtesy of the presence of the OEt/OBn
moiety; such instability has been previously reported in pyrrole–
rhenium complexes.14
As such, we sought to use pyrroles that featured a halide
substituent, especially as complex 2h (Table 2, within the
formyl series) had been prepared in essentially quantitative
yield. Several 2-carboxylato-functionalized pyrroles of this
genre were subsequently complexed to ruthenium(II) (Table 3,
entries 3–5), albeit in yields lower than for the aldehydes and
ketones.
–
NH4PF6 so that the complex could be isolated as the PF6
salt via precipitation. Other counterions were employed, in-
cluding triflate, tetraphenyl borate, and 3-TMS-1-propane sul-
fonate, but hexafluorophosphate provided complexes that
precipitated the most readily.
Purification was achieved through the dissolution of the
crude precipitate in dichloromethane (DCM), washing the
solution with brine, and then drying the organic fraction over
sodium sulfate. The solvent was removed in vacuo, and the
resulting film was triturated with hexanes to give a solid that
could be collected using a Millipore filter. Microwave irradi-
ation was essential for the formation of these complexes,
since conventional heating methods gave no complexation
products. The temperature and time of reaction were both op-
2-Sulfinyl and 2-sulfonyl pyrroles
The final set of ligands contained a sulfinyl moiety at the
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Lundrigan et al.
695
Table 2. Isolated yields of 2-formyl and 2-keto pyrrolide ruthenium(II) complexes.
Isolated
yield (%)
Entry
Complex
1
2
3
4
5
6
7
8
9
1a, R1 = Me, R2 = Et, R3 = Me, R4 = H
1b, R1 = Me, R2 = Me, R3 = Me, R4 = H
1c, R1 = Me, R2 = H, R3 = Me, R4 = H
1d, R1 = H, R2 = H, R3 = H, R4 = H
1e, R1 = H, R2 = Et, R3 = Me, R4 = H
1f, R1 = Me, R2 = Heptyl, R3 = Me, R4 = H
1g, R1 = Me, R2 = Et, R3 = Me, R4 = Ph
1h, R1 = Br, R2 = H, R3 = H, R4 = Ph
1i, R1 = Me, R2 = Heptyl, R3 = Me, R4 = Ph
2a
2b
2c
2d
2e
2f
2g
2h
2i
93
75
77
81
71
74
80
99
82
Scheme 2. Synthetic route to pyrrolide ester ruthenium(II) complexes.
Table 3. Isolated yields of various pyrrolide ester ruthenium(II) complexes.
Isolated
yield
(%)
0
0
75
70
70
Entry
Complex
1
2
3
4
5
3a, R1 = Me, R2 = Et, R3 = Me, R4 = Et
3b, R1 = Me, R2 = Et, R3 = Me, R4 = Bn
3c, R1 = H, R2 = Br, R3 = Me, R4 = Et
3d, R1 = I, R2 = Me, R3 = Et, R4 = Et
3e, R1 = I, R2 = Me, R3 = Me, R4 = Et
4a
4b
4c
4d
4e
2-position (Scheme 3). These 2-(arylsulfinyl)pyrroles26 are of
special interest as they contain a chiral centre at the sulfox-
ide. Each ligand was synthesized as a racemate. Various aryl
groups were substituted on the sulfur centre, with little sub-
stitution around the pyrrole ring, and these ligands were suc-
cessfully complexed (Table 4, entries 1–3), although in yields
generally lower than those for complexes containing pyrrolyl
ligands bearing 2-carbonyl moieties. Diastereoselectivity
within the complexation reaction was not observed.
For pyrroles 5d and 5e a formyl group was introduced at
the 5-position to investigate binding competition between the
two potential coordination sites (Table 4, entries 4 and 5).
Comparing the carbonyl stretching frequencies of pyrrole 5d
to complex 6d reveals that the frequency is red-shifted from
1670 cm–1 in the free ligand to 1545 cm–1 in the complex. A
similar result is found when comparing the carbonyl stretch-
ing frequencies of pyrrole 1a (1619 cm–1) with that of com-
plex 2a (1578 cm–1). As such, coordination must occur
through the formyl group in each case, indicating that this
coordination site is more favourable than the sulfinyl group.
Complexes 6f and 6g were synthesized using 2-(arylsulfenyl)
and 2-(arylsulfonyl) pyrroles, respectively, to demonstrate
that complexation can occur with pyrroles bearing 2-sulfur
substituents at the sulfenyl, sulfinyl, and sulfonyl oxidation
states (Table 4, entries 6 and 7).
All complexes 2, 4, and 6, are air- and moisture-stable.
They are deep red in the solid state and appear dark bur-
gundy in solution, except complexes 6d–6f, which are red-
orange in solution. Each product was fully characterized
using 1H NMR, 13C NMR, and UV–vis spectroscopy, as
well as ESI-MS. Futhermore, several complexes were char-
acterized using X-ray crystallography.
The absorption spectra of these complexes are character-
ized by intense p→p* intraligand transitions in the UV range
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696
Can. J. Chem. Vol. 90, 2012
Scheme 3. Synthetic route to pyrrolide sulfinyl ruthenium(II) complexes.
Table 4. Isolated yields of pyrrolide sulfinyl ruthenium(II) complexes.
Isolated
yield (%)
Entry
Complex
1
2
3
4
5
6
7
5a, R1 = H, R2 = Ph
6a
6b
6c
6d
6e
6f
55
60
70
70
93
75
45
5b, R1 = H, R2 = p-tolyl
5c, R1 = H, R2 = naphthyl
5d, R1 = CHO, R2 = Ph
5e, R1 = CHO, R2 = p-tolyl
5f, R1 = CHO, R2 = Ph (sulfenyl)
5g, R1 = H, R2 = Ph (sulfone)
6g
Fig. 2. UV–vis spectrum of 2a in dichloromethane (DCM), with labeled transitions.
Fig. 3. Thermal ellipsoid diagram (50%) of 2a·CHCl3.
and metal-to-ligand charge transfer (MLCT) transitions,
dp(Ru)→p*(L), in the visible region27–29 (Fig. 2). The spec-
trum for complex 2a shows the general trend of the absorption
spectra for these complexes, consisting of the intense
p→p* bipy-localized transitions below 300 nm,28 as well
as lower energy bands (So→S1) between 300 and 400 nm.
Each complex exhibits a broad MLCT transition containing
a shoulder, explained by the overlapping dp(Ru)→p* ab-
sorptions from the bipyridyl and pyrrolide ligands, and
these bands are located above 450 nm.
X-ray crystallographic data were collected for several of
the new complexes (2a, 2b, 2d, 2g, and 4e), with structures
being obtained for pyrrolide 2-formyl, 2-keto, and 2-carboxylate
ruthenium(II) complexes. The structural details for 2b and
2d are included in the Supplementary data, as are those for
1a and 1d. Complex 2a (2-formyl group) crystallizes in the
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Lundrigan et al.
697
Fig. 4. Thermal ellipsoid diagrams (50%) showing bond lengths of the parent pyrrole (left, 1a) and the corresponding coordinated pyrrolide
(right, partial structure of 2a); hydrogen atoms are omitted for clarity.
Fig. 5. Resonance structures of complexed pyrrolide (left, pyrrole; right, azafulvenium).
space group P-1, with one enantiomer of the complex occu-
pying the asymmetric unit. The geometry of the ruthenium(II)
centre was found to be distorted octahedral (Fig. 3).
Fig. 6. Thermal ellipsoid diagram (50%) of 2g.
The Ru–Nbipy bond lengths are in the range of 2.029(2)–
2.065(1) Å and the Ru–Npyrrole bond length is 2.076(2) Å.
The Ru–O bond length is longer at 2.097(2) Å. These Ru–O
and Ru–N bond lengths are shorter than those found in sim-
ilar pyrrole–ruthenium complexes.18 To enable comparison of
the structures of the uncoordinated pyrrole with the pyrrolide
ligand within the complex, X-ray crystallographic data were
obtained for the pyrrole 1a (Fig. 4).
Analysis of the structures reveals that there is a lengthening
of the C–O bond in the complex 2a (1.292(7) Å) with respect
to the C–O bond of the pyrrole 1a (1.226(2) Å). Furthermore,
the C4–C5 bond length (1.395(7) Å) in 2a, which is formally
a C–C single bond from the pyrrole to the carbonyl carbon
atom, is shorter than in the corresponding bond in the parent
pyrrole 1a (1.419(2) Å). The formal C1–C2 C=C double
bond of the pyrrole ring (1.445(8) Å) is longer in 2a than the
pyrrole 1a (1.388(2) Å) (Fig. 4). It appears that all bonds
have taken on double bond character, as is typical for an aro-
matic system. However, the increased C–O and C1–C2 bond
lengths in 2a suggest that the major resonance form of the
pyrrolide ligand is the azafulvenium variant (Fig. 5).
Complex 2g (2-keto group) crystallizes in the space group
P21/n with the geometry at the ruthenium(II) centre again
being distorted octahedral (Fig. 6). The Ru–Nbipy bonds fall
in the range of 2.035(2)–2.059(2) Å, and the Ru–Npyrrole and
Ru–O bond lengths were both found to be 2.076(2) Å. The
C–O bond length of pyrrole 1g22 (1.2434(9) Å) is shorter
than the same bond in complex 2g (1.284(3) Å). It appears
that this ligand follows the same trend shown in complex 2a.
The C1–C2 and C4–C5 bond lengths in pyrrole 1g (1.397(1)
and 1.441(1) Å, respectively) undergo a similar increase and
decrease upon complexation (1.423(5) and 1.399(4) Å, re-
spectively, for complex 2g).
Complex 4e (2-carboxylate) also crystallizes in the space
group P21/n with distorted octahedral geometry at the ruthe-
nium(II) centre (Fig. 7). The Ru–Nbipy bond lengths are be-
tween 2.016(2) and 2.053(3) Å and the Ru–Npyrrole bond
lengths are 2.087(2) and 2.088(3) Å. The Ru–O bond lengths
are 2.1281(19) and 2.134(2) Å, which are much longer than
those of the 2-formyl and 2-keto pyrrole–ruthenium com-
plexes.
Conclusion
In summary, the first heteroleptic pyrrolyl 2,2’-bipyridine
complexes of ruthenium(II) are reported, along with a reliable
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698
Can. J. Chem. Vol. 90, 2012
Fig. 7. Thermal ellipsoid diagram (50%) of 4e.
was added triethylamine (0.5 mL). The resulting solution
was reacted in a laboratory microwave at a controlled tem-
perature of 125 °C for 60 min and then cooled to room
temperature with a pressurized air supply. The cooled reac-
tion mixture was added to a solution of NH4PF6 (3.1 mmol)
in deionized water (100 mL). The suspension was stirred
overnight and the resulting precipitate was then collected
via suction filtration. Purification was achieved by dissolv-
ing the precipitate in DCM (80 mL), washing with brine
(80 mL), and drying the organic fraction with sodium sul-
fate. After filtration, the solvent was removed in vacuo.
The resulting film was triturated with hexanes and the re-
sulting solid was collected using a Millipore filter.
Representative synthesis
Bis(2,2’-bipyridyl)-(4-ethyl-2-formyl-3,5-dimethyl-N-
pyrrolato)ruthenium(II) hexafluorophosphate (2a)
Complex 2a was synthesized using GP1 and pyrrole 1a
and was isolated as a microcrystalline dark burgundy solid
(0.115 g, 93%). Crystals suitable for X-ray diffraction analy-
sis were grown via the diffusion of hexane into a concen-
trated chloroform solution. UV–vis (DCM) lmax (nm): 296 3
115 000 L mol–1 cm–1, 375 3 40 000 L mol–1 cm–1, 536 3
20 000 L mol–1 cm–1. dH (500 MHz, CDCl3): 8.63 (1H, d,
J = 4.9), 8.39 (1H, d, J = 8.0), 8.36 (1H, d, J = 8.2),
8.30 (1H, d, J = 8.2), 8.26 (1H, d, J = 8.1), 8.21 (1H, s),
7.99–7.95 (2H, m), 7.89 (1H, d, J = 5.7), 7.79–7.72 (3H,
m), 7.54–7.51 (1H, m), 7.49 (1H, d, J = 5.6), 7.46–7.44
route for their high-yielding syntheses. A wide variety of
pyrrolyl ligands containing numerous functionalities have
been successfully coordinated to ruthenium(II) producing air-
and moisture-stable complexes. The general synthetic method
described should provide a route to pyrrolide–ruthenium
complexes of various bidentate pyrroles and potentially a
pathway to alternative pyrrolide-bound transition-metal com-
plexes.
(1H, m), 7.18–7.16 (2H, m), 2.29–2.23 (5H, m, CH2
+
CH3), 1.26 (3H, s), 0.95 (3H, t, J = 7.5). dC (125 MHz,
DMF-d7): 176.0, 160.0, 159.4, 158.8, 158.3, 153.9, 153.7,
152.5, 152.5, 151.3, 142.5, 136.9, 136.7, 136.1, 135.4,
133.2, 130.5, 127.6, 127.4, 127.4, 127.1, 124.5, 124.1,
124.1, 123.9, 18.1, 15.3, 12.3, 10.1. m/z [M – PF6 + H+]:
564.1. Crystal data for complex 2a: C30H29N5OPF6RuCl3,
MM = 827.99 g/mol, dark-red needle crystal, 0.31 mm ×
0.13 mm × 0.06 mm; primitive triclinic, space group P-1; a =
9.8219(4) Å; b = 13.6422(5) Å; c = 13.7188(3) Å; a =
Experimental section
General experimental
1
All H NMR (500 MHz) and 13C NMR (125 MHz) spectra
were recorded on a Bruker Avance AV-500 spectrometer.
Chemical shifts are expressed in parts per million (ppm) us-
1
ing the solvent signals (CDCl3, H NMR 7.26 ppm; CD2Cl2,
1H NMR 5.26 ppm, 13C NMR 53.8 ppm; DMF-d7, H NMR
1
2.74 ppm, 13C NMR 30.1 ppm) as an internal reference for
73.941(8);
b = 73.983(11); g = 87.603(12)°; V =
1H and 13C. Splitting patterns are indicated as follows: br,
broad; s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet;
and app, apparent. All coupling constants (J) are reported in
Hertz (Hz). Mass spectra were obtained using ion trap (ESI)
instruments operating in positive mode. All microwave reac-
tions were performed using a Biotage Initiator laboratory mi-
crowave apparatus. The following compounds were prepared
according to literature procedures: 1a,30 1b,30 1c,2 1d,30 1e,31
1g,32 1h,33 3c,34 3d,35 3e,36 and 5a–5g.26 Measurements were
made on a Rigaku Raxis rapid-imaging plate area detector
with graphite-monochromated Mo Ka radiation. The struc-
tures were solved by direct methods37 and expanded using
Fourier techniques.38 The non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were refined using the rid-
ing model. Calculations were performed using the Crystal-
Structure39,40 crystallographic software package.
1696.72(15) Å3; Z = 2; r = 1.621 g/cm3; µ(Mo Ka) =
0.8115 mm–1; 22 241 reflections (11 932 unique, Rint
0.052); R(F) = 0.0596; Rw(F) = 0.0713; GoF = 1.120.
=
Bis(2,2’-bipyridyl)-(4-ethyl-3,5-dimethyl-2-benzoyl-N-
pyrrolato)ruthenium(II) hexafluorophosphate (2g)
Complex 2g was synthesized using GP1 and pyrrole 1g
and was isolated as a microcrystalline dark burgundy solid
(0.110 g, 80%). Crystals suitable for X-ray diffraction analy-
sis were grown via the slow evaporation of solvent from a
concentrated methanol solution. UV–vis (DCM) lmax (nm):
296 3 125 000 L mol–1 cm–1, 330 3 35 000 L mol–1 cm–1,
540 3 25 000 L mol–1 cm–1. dH (500 MHz, DMF-d7): 8.87
(1H, d, J = 8.0), 8.84 (1H, d, J = 8.1), 8.81 (1H, d, J =
8.2), 8.79–8.76 (2H, m), 8.21–8.18 (2H, m), 8.16–8.14 (1H,
m), 8.09 (1H, d, J = 5.3), 8.00–7.98 (2H, m), 7.84–7.81 (1H,
m), 7.78 (1H, d, J = 5.6), 7.73–7.70 (1H, m), 7.49–7.46 (1H,
m), 7.44–7.40 (6H, m), 2.26 (2H, m, J = 7.1), 1.81 (3H, s),
1.39 (3H, s), 0.90 (3H, t, J = 7.5). dC (125 MHz, CD2Cl2):
186.2, 159.3, 158.8, 158.3, 157.8, 153.5, 152.9, 152.2,
151.6, 151.1, 138.6, 136.2, 136.0, 135.3, 134.6, 133.0,
General procedure for the synthesis of ruthenium
complexes (GP1)
To
a
solution of the pyrrole (0.19 mmol) and
Ru(bipy)2Cl2·2H2O (0.17 mmol) in ethylene glycol (16 mL)
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Lundrigan et al.
699
132.0, 130.2, 128.5 (2C), 128.3 (2C), 127.0, 126.9, 126.7,
126.6, 123.6, 123.3, 123.2, 123.0, 18.2, 15.2, 12.6, 12.2,
1Ar-C signal missing. m/z [M – PF6 + H]+: 640.2. Crystal
data for complex 2g: C35H32N5OPF6Ru, MM = 784.70 g/mol,
dark-red spear crystal, 0.36 mm × 0.14 mm × 0.09 mm;
primitive monoclinic, space group P21/n; a = 11.7187(11) Å;
b = 14.9960(12) Å; c = 19.2788(13) Å; V = 3366.0(5) Å3;
Z = 4; r = 1.548 g/cm3; µ(Mo Ka) = 57.48 mm–1; 24 900
reflections (6842 unique, Rint = 0.050); R = 0.0358, Rw =
0.0412; GoF = 1.080.
Supplementary data
Supplementary data are available with the article through
the journal Web site at http://nrcresearchpress.com/doi/suppl/
10.1139/v2012-045. CCDC 846489–846495 contain the X-
ray data in CIF format for this manuscript. These data can
be obtained, free of charge, via http://www.ccdc.cam.ac.uk/
products/csd/request (Or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: +44 1223 33603; or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgements
Bis(2,2’-bipyridyl)-(ethyl 5-iodo-3,4-methylpyrrole-2-
carboxylato-N-pyrrolato)ruthenium(II)
This work was supported by the Natural Sciences and En-
gineering Research Council of Canada (NSERC). The au-
thors thank Beth Pearce, Dr. H. Martin Gillis, and Dr. Jose
R. Garabatos-Perera (all previous members of the Thompson
group at Dalhousie University) for the preparation of com-
pounds 5d, 5f, and 5g.
hexafluorophosphate (4e)
Complex 4e was synthesized using GP1 and pyrrole 3e
was isolated as a microcrystalline dark burgundy solid
(0.104 g, 70%). Crystals suitable for X-ray diffraction analy-
sis were grown via the diffusion of diethyl ether into a con-
centrated DCM solution. UV–vis (DCM) lmax (nm): 295 3
80 000 L mol–1 cm–1, 345 3 15 000 L mol–1 cm–1, 518 3
10 000 L mol–1 cm–1. dH (500 MHz, CD2Cl2): 8.65 (1H,
dd, J = 5.6, 0.6), 8.35 (2H, dd, J =11.7, 8.1), 8.28 (1H, d,
J = 8.1), 8.22 (1H, d, J = 8.0), 8.03–7.98 (3H, m), 7.84
(1H, td, J = 7.9, 1.3), 7.73–7.68 (2H, m), 7.59 (1H, ddd, J =
7.4, 5.8, 1.4), 7.53 (1H, dd, J = 5.6, 0.6), 7.50 (1H, ddd, J =
7.4, 5.8, 1.4), 7.19 (1H, ddd, J = 7.4, 5.8, 1.4), 7.07 (1H,
ddd, J = 7.4, 5.9, 1.4), 4.27–4.24 (1H, m), 4.14–4.11 (1H,
m), 2.24 (3H, s), 1.83 (3H, s), 1.19 (3H, t, J = 7.1). dC
(125 MHz, CD2Cl2): 173.0, 160.1, 159.2, 158.3, 158.1,
154.3 (2C), 152.3, 150.6, 136.5, 136.4, 135.8, 135.0, 129.9,
129.4, 127.3, 127.1, 126.8, 126.7, 126.3, 123.7, 123.4,
123.2, 122.9, 97.6, 62.6, 14.5 (2C), 12.7. m/z [M – PF6 + H]+:
706.0. Crystal data for complex 4e: 2(C29H27N5OPF6Ru)
CH2Cl2 H2O, MM = 1803.95 g/mol, deep-red block crystal,
0.28 mm × 0.17 mm × 0.09 mm; primitive monoclinic,
space group P21/n; a = 23.1502(7) Å; b = 13.8523(3) Å;
c = 23.3484(6) Å; b = 117.0574(10)°; V = 6668.0(3) Å3; Z =
4; r = 1.797 g/cm3; µ(Mo Ka) = 1.5965 mm–1; 111 925
reflections (26 270 unique, Rint = 0.039); R(F) = 0.0325;
Rw(F) = 0.0373; GoF = 1.058.
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Bis(2,2’-bipyridyl)-(2-(naphthylsulfinyl)-N-pyrrolato)
ruthenium(II) hexafluorophosphate (6c)
Complex 6c was synthesized using GP1 and pyrrole 5c was
isolated as a microcrystalline dark burgundy solid (0.098 g,
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114.1, 112.2. m/z [M – PF6 + H]+: 654.1.
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