Ruthenium acetylide complexes supported by trithiacyclononane and aromatic diimine: Structural, spectroscopic, and theoretical studies

Article abstract of DOI:10.1021/om900511t

Ruthenium(II)-acetylide complexes bearing 1,4,7-trithiacyclononane ([9]aneS3) and 1,10-phenanthroline (phen) have been prepared. The molecular structure of [([9]aneS3)(phen)Ru-C=CPh]⁺ shows that the trans influence of the acetylide ligand is on

Full text of DOI:10.1021/om900511t

5656 Organometallics 2009, 28, 5656–5660
DOI: 10.1021/om900511t
Ruthenium Acetylide Complexes Supported by Trithiacyclononane and
Aromatic Diimine: Structural, Spectroscopic, and Theoretical Studies
Chun-Yuen Wong,* Lo-Ming Lai, and Pak-Kei Pat
Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon,
Hong Kong SAR, People’s Republic of China
Received June 16, 2009
Ruthenium(II)-acetylide complexes bearing 1,4,7-trithiacyclononane ([9]aneS3) and 1,10-phenanthro-
line (phen) have been prepared. The molecular structure of [([9]aneS3)(phen)Ru-CtCPh]þ shows that
the trans influence of the acetylide ligand is only slightly weaker than that of isocyanide and is stronger
than that of chloride. The Ru(II/III) oxidation waves for the complexes are irreversible, with Epa
0.30-0.39 V vs Cp2Feþ/0. The lowest-energy dipole-allowed absorptions for the complexes (λmax
=
=
441-466 nm, εmax = (4-5) ꢀ 103 dm3 mol-1 cm-1) are assigned as dπ(RuII) f π*(phen) metal-to-ligand
charge transfer (MLCT) transitions. The complexes are emissive in glassy MeOH/EtOH at 77 K upon
photoexcitation and give emission at λmax =606-623 nm. Density functional theory (DFT) calculations
and charge decomposition analysis (CDA) have been used to probe the Ru-C bonding interaction in
these complexes, and the results are compared with their isocyanide congeners. The rotational barrier for
the phenyl ring in [([9]aneS3)(phen)Ru-CtCPh]þ is calculated to be 0.53 kcal mol-1, suggesting that the
Ru-C π-interaction in these complexes is weak and cannot lock the rotational motion of the acetylide
ligand effectively.
Ruthenium(II) complexes containing aromatic diimine
ligands such as 2,20-bipyridine (bpy) and 1,10-phenanthro-
line (phen) represent an important class of luminophore
based on transition metal complexes. They exhibit rich
photophysical and photochemical properties, which origi-
nate from the triplet [dπ(RuII) f π*(aromatic diimine)]
metal-to-ligand charge transfer (3MLCT) excited state. The
use of these complexes in photochemistry,1 electron transfer
reactions,2 luminescent sensing,3 light-emitting devices,4 and
photosensitizers5 has attracted much attention, and the
pursuit of [Ru(bpy)3]2þ-related complexes exhibiting desir-
able photophysical properties continues unabated.6
For ruthenium(II)-aromatic diimine complexes with gen-
eral formula [Ru(diimine)x(L)y]nþ, their photophysical prop-
erties can be fine-tuned by controlling the energy level of the
π*(diimine) orbital via modifying the degree of conjugation
in the diimine ligands. An alternative approach would be
tuning the energy of the dπ(RuII) level via manipulating the
Ru-L interaction. We previously probed the metal-carbon
bonding interaction in [(Me3Tacn)(phen)RudC(OMe)R]2þ
,
*Corresponding author. E-mail: acywong@cityu.edu.hk.
[(Me3Tacn)(phen)RudCdCdCR2]2þ, [(Me3Tacn)(phen)Ru-
(CNR)]2þ, and [([9]aneS3)(phen)Ru(CNR)]2þ (Me3Tacn =
1,4,7-trimethyl-1,4,7-triazacyclononane; [9]aneS3=1,4,7-tri-
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pubs.acs.org/Organometallics
Published on Web 09/16/2009
2009 American Chemical Society

Article
Organometallics, Vol. 28, No. 19, 2009 5657
Table 1. Electrochemical Data for Complexes 1-3(PF6),
[([9]aneS3)(phen)RuCl](PF6), and [([9]aneS3)(phen)Ru(t-
a
BuNC)](PF6)2
complex
E1/2b/V vs Cp2Feþ/0
1
2
3
-1.92
0.39c
0.37c
0.30c
0.74
-1.92
-1.92
-1.92c
-1.76c
[([9]aneS3)(phen)RuCl]þ
[([9]aneS3)(phen)Ru(t-BuNC)]2þ
1.50
a Supporting electrolyte: 0.1 M [Bu4N]PF6 in CH3CN. b E1/2 = (Epc
Epa)/2at298 K for reversible couples. c Irreversible;the recorded potential
is the peak cathodic or anodic potential at scan rate of 100 mV s-1
þ
.
Table 2. UV-Visible Absorption and Emission Data for Com-
plexes 1-3
Figure 1. Perspective view of the cation in 1(PF6) (thermal
ellipsoids are drawn at 50% probability). Selected bond
lengths (A) and angles (deg): Ru(1)-C(1) 2.028(3), C(1)-C(2)
1.200(4), C(2)-C(3) 1.440(4), mean Ru(1)-Nphen 2.089, mean
Ru(1)-S[9]aneS3-cis 2.3018, Ru(1)-S[9]aneS3-trans 2.3553(7), Ru-
(1)-C(1)-C(2) 175.0(2), C(1)-C(2)-C(3) 176.0(3).
complex
λ
max/nm (εmax/dm3 mol-1 cm-1 a
)
λ
em/nmb
˚
1
2
3
267 (36 830), 297 (sh, 16 040), 441 (3970)
268 (41 170), 289 (sh, 25 510), 466 (4260)
268 (45 610), 288 (sh, 28 790), 466 (4550)
606
617
623
a Solvent = CH3CN; 298 K. b Solvent = MeOH/EtOH (1:4 v/v);
77 K; λex = 470 nm.
Scheme 1
2081-2085 cm-1 for 1-3 are comparable to reported values
for Ru(II)-acetylide complexes.9
The molecular structure of 1(PF6) was determined by
X-ray crystallography (Figure 1). The Ru atom adopts a
distorted octahedral geometry, with the [9]aneS3 facially
˚
coordinating to it. The Ru-C distance in 1 (2.028(3) A) is
similar to those in [Ru(CtCH)(cym)(phen)] (2.022(9) A),
þ
10
˚
[Ru(Me2bipy)(PPh3)2Cl(CtCBu )] (2.053(5) A),11 and [Ru-
t
˚
(tpy)(bpy)(CtCAr)]þ (2.025(7)-2.025(9) A), and it is
12
˚
longer than that in the isocyanide congeners [([9]aneS3)-
(phen)Ru(t-BuNC)]2þ (1.984(3) A) by 0.044 A. Interest-
ingly, it is noted that within the [([9]aneS3)(phen)RuL]nþ
series the structural trans influence of acetylide is only
slightly weaker than that of isocyanide and is stronger than
8
˚
˚
thiacyclononane)7,8 and demonstrated that manipulating
the Ru-C bonding interaction can effectively modulate
the photophysical properties of the [Ru(diimine)] lumino-
phore. As an extension of this research, we now present
the preparation and electrochemical, spectroscopic, and
theoretical investigations for a series of luminescent ruthe-
nium(II)-arylacetylide complexes bearing [9]aneS3 and
phen.
that of chloride: Ru-S[9]aneS3-trans distance in [([9]aneS3)-
8
(phen)Ru(t-BuNC)]2þ (2.3723(7) A) ≈ 1 (2.3553(7) A) >
˚
˚
13
[([9]aneS3)(phen)RuCl]þ (2.272(2) A). This is consistent
˚
with the findings for trans-[PtL(Cl)(PR3)2] and AuL(PPh3),
which indicate that the trans influence of acetylide ligands is
significantly greater than that of chloride.9
Cyclic voltammetry was used to examine the electrochem-
istry of complexes 1-3, [([9]aneS3)(phen)RuCl]þ, and [([9]-
aneS3)(phen)Ru(t-BuNC)]2þ (Table 1; all values vs Cp2Feþ/0).
Complexes 1-3 show a reversible couple at E1/2 = -1.92 V
and an irreversible wave at Epa = 0.30 to 0.39 V (scan rate =
100 mV s-1, 0.1 M [Bu4N]PF6 in CH3CN as supporting
electrolyte). The reduction couples for 1-3 are assigned as
reduction of the phen ligands, whereas the oxidation waves
are assigned as metal-centered Ru(II/III) oxidations. The
span in the Epa values for the Ru(II/III) oxidation from R =
Ph (1) to C6H4OMe-4 (3) is 90 mV, suggesting that the
highest-occupied molecular orbitals (HOMOs) of 1-3 may
contain a contribution from the acetylide ligand. The more
positive E1/2 values of the Ru(II/III) redox couple for
Results and Discussion
Acetylide complexes [([9]aneS3)(phen)Ru-CtCR]þ (1-3)
were prepared in ca. 80% yields by reacting HCtCR with
[([9]aneS3)(phen)RuCl]þ in the presence of KOH in refluxing
methanol (Scheme 1). Slow diffusion of Et2O into an acetone
or acetonitrile solution yielded analytically pure bright yellow
or orange crystalline solids, which are sufficiently stable to be
handled in air under ambient conditions in solution and solid
forms. For example, the UV-visible spectrum of 1 remains
unchanged in CH3CN after 1 week. Complexes 1-3 feature
four sets of 1H NMR signals for the phen ligands and three sets
of 13C signals for the [9]aneS3 ligands, signifying that com-
plexes 1-3 possess a pseudo plane of symmetry in solution on
the NMR time scale at room temperature. This is consistent
with the finding that the rotational barrier for the phenylace-
tylide ligand in 1 is low (calculated to be 0.53 kcal mol-1, see
discussion below). The ν(CtC) stretching frequencies at
(9) Manna, J.; John, K. D.; Hopkins, M. D. Adv. Organomet. Chem.
1995, 38, 79.
ꢁ
ꢁ
(10) Menendez, C.; Morales, D.; Perez, J.; Riera, V.; Miguel, D.
Organometallics 2001, 20, 2775.
(11) Adams, C. J.; Pope, S. J. A. Inorg. Chem. 2004, 43, 3492.
(12) Wong, C.-Y.; Chan, M. C. W.; Zhu, N.; Che, C.-M. Organome-
tallics 2004, 23, 2263.
(7) Wong, C.-Y.; Lai, L.-M.; Lam, C.-Y.; Zhu, N. Organometallics
2008, 27, 5806.
(8) Wong, C.-Y.; Lai, L.-M.; Leung, H.-F.; Wong, S.-H. Organome-
ꢁ
(13) Goodfellow, B. J.; Felix, V.; Pacheco, S. M. D.; Pedrosa de Jesus,
tallics 2009, 28, 3537.
J.; Drew, M. G. B. Polyhedron 1997, 16, 393.

5658 Organometallics, Vol. 28, No. 19, 2009
Wong et al.
that the HOMOs of 1-3 may contain a contribution from the
acetylide ligand. A similar argument was proposed in the
photophysical studies of [(tpy)(bpy)Ru(CtCR)]þ (tpy =
2,20:60,200-terpyridine).12 Importantly, our DFT calculations
show that the acetylide ligand has a significant contribution
in the HOMO of [([9]aneS3)(phen)Ru(CtCR)]þ (see discus-
sion below). Since complexes 1-3 are not highly emissive in
solution form at room temperature, their emission properties
were examined in glassy MeOH/EtOH (1:4, v/v; 77 K) solution.
Excitation of 1-3 at λ = 470 nm gives emission at λmax
=
606-623 nm (Figure 2, Table 2), which are red-shifted in
energy compared with that of [([9]aneS3)(phen)Ru(t-Bu-
NC)]2þ (λmax=477 nm).8 Since a similar red-shift is noted for
the dπ(RuII) f π*(phen) MLCT absorption energies, the
emissions for [([9]aneS3)(phen)Ru(CtCR)]þ are ascribed as
dπ(RuII) f π*(phen) 3MLCT in nature.
Figure 2. Absorption (solid line; CH3CN; 298 K) and emission
(dash line; MeOH/EtOH, 1:4, v/v; 77 K, λex = 470 nm) spectra of 1.
[([9]aneS3)(phen)RuCl]þ and [([9]aneS3)(phen)Ru(t-BuNC)]2þ
compared with 1-3 can be rationalized by the fact that (1)
Cl- has a higher electronegativity than -CtCR, and (2) the
electronic charge in the isocyanide complex (þ2) is higher than
those in acetylide complexes (þ1).
Density functional theory (DFT) calculations were per-
formed on 1, 3, and [([9]aneS3)(phen)Ru(t-BuNtC)]2þ in or-
der to provide more insight on the Ru-C bonding interaction
in 1-3. The ground-state structures of these complexes were
optimized at the DFT level (PBE1PBE).15 The PBE1PBE
functional was employed because it had been used to calculate
ruthenium-acetylide,14 -allenylidene,7 -alkoxycarbene,7,16
and isocyanide8 systems, and satisfactory results had been ob-
tained. Frequency calculations were also performed on the
optimized structures. As no imaginary vibrational frequencies
were encountered, the optimized stationary points were con-
firmed to be local minima. Detailed optimized structural data
are summarized in the Supporting Information. Table 3 sum-
marizes the compositions of the highest-occupied molecular
orbitals (HOMOs) and the lowest-unoccupied molecular
orbitals (LUMOs) for 1, 3, and [([9]aneS3)(phen)Ru(t-
BuNC)]2þ. The calculated energies of the HOMOs are in the
order 3 (-6.97 eV) > 1 (-7.39 eV) . [([9]aneS3)(phen)Ru(t-
BuNC)]2þ (-12.19 eV), and those of the LUMOs are in the
order 3 (-4.60 eV) ≈ 1 (-4.65 eV) > [([9]aneS3)(phen)Ru(t-
BuNC)]2þ (-7.61 eV). These parallel the experimental trends
of the oxidation and reduction potentials for the correspond-
ing complexes: (1) For oxidation waves, Epa = 0.30 V for
3, 0.39 V for 1, and E1/2=1.50 V for [([9]aneS3)(phen)Ru(t-
BuNC)]2þ; (2) for reduction waves, E1/2=-1.92 V for 1 and 3,
The UV-visible spectral data for 1-3 are summarized
in Table 2, and the absorption spectrum of 1 is depicted
in Figure 2. All complexes exhibit intense high-energy
absorption at λmax e 350 nm (εmax g 104 dm3 mol-1
cm-1) and moderately intense bands at λmax = 441-466 nm
(εmax = (4-5) ꢀ 103 dm3 mol-1 cm-1) as their lowest-energy
electronic transition. In the literature, ruthenium(II) complexes
bearing aromatic diimine ligands such as [Ru(bpy)3]2þ and
[Ru(phen)3]2þ feature two types of characteristic absorption
bands: highly intense absorptions in the UV region, which are
attributed to the diimine intraligand π f π* transitions, and
moderately intense absorptions in the visible region, which are
ascribed to dπ(RuII) f π*(diimine) metal-to-ligand charge
transfer (MLCT) transitions.1d In this work, the lowest-energy
absorptions at λmax = 441-466 nm for 1-3 are assigned as
dπ(RuII) f π*(phen) metal-to-ligand charge transfer (MLCT)
transitions. Assigning the lowest-energy absorptions for 1-3 to
dπ(RuII) f π*(CtCR) MLCT transitions is unreasonable
because the dπ(RuII) f π*(CtCR) MLCT transition for
trans-[Ru(16-TMC)(CtCPh)2] (16-TMC = 1,5,9,13-tetra-
methyl-1,5,9,13-tetraazacyclohexadecane) occurs at 397 nm.14
In any case, the dπ(RuII) f π*(CtCR) MLCT transitions in
1-3 should appear at a higher energy than for derivates
supported by 16-TMC because 16-TMC is a stronger σ-donor
and weaker π-acceptor than the ([9]andS3)(phen) ligand set. It
is noted that the dπ(RuII) f π*(phen) MLCT transitions for
1-3 are not Gaussian in appearance, which is likely due to the
presence of a strong (unresolved) vibronic sideband. A similar
non-Gaussian dπ(RuII) f π*(phen) MLCT transition profile
-1.76 V for [([9]aneS3)(phen)Ru(t-BuNC)]2þ
.
It is noted that the HOMOs and LUMOs of 1 and 3 are
delocalized along the [Ru(CtCPh)] and [Ru(phen)] moi-
eties, respectively. Moreover, the frontier orbitals of [([9]-
aneS3)(phen)RuL]2þ are sensitive to the Ru-L bonding
interactions: the HOMO-LUMO gaps for 1 and 3 are smal-
ler than that for isocyanide-ligated complex [([9]aneS3)-
(phen)Ru(t-BuNtC)]2þ by about 2 eV. Such sensitivity is
important, as it provides a way to manipulate the photo-
physical properties of [([9]aneS3)(phen)RuL]2þ, as demon-
strated in the above photophysical studies. Charge decom-
position analysis (CDA)17 for the interaction between the
closed-shell fragment [([9]aneS3)(phen)Ru]2þ and -CtCPh
was performed (Table 4) and compared with the result for
[([9]aneS3)(phen)Ru(t-BuNtC)]2þ. Since the residue terms
(Δ) are essentially zero, the Ru-acetylide complexes in
this work can be discussed within the framework of the
has been observed in [(Me3Tacn)(phen)RudC(OMe)R]2þ
[(Me3Tacn)(phen)Ru(CH3CN)]2þ
[(Me3Tacn)(phen)Ru(t-
BuNC)]2þ, and [([9]aneS3)(phen)Ru(t-BuNC)]2þ 7,8
The dπ-
,
,
.
(RuII) fπ*(phen) MLCT transition for 1-3is found to be red-
shifted compared with that of [([9]aneS3)(phen)Ru(t-Bu-
NC)]2þ (λmax = 330 nm).8 This suggests that the dπ(RuII) level
in the [([9]aneS3)(phen)Ru]2þ core is destabilized to a greater
extent by acetylide, revealing that acetylide is a greater σ-donor
and weaker π-acceptor than isocyanide. It is also noted that the
dπ(RuII) f π*(phen) MLCT transition is sensitive to the
change of substituent on the arylacetylide ligand: the λmax of
the MLCT transition is 441 nm for 1(R = Ph) and 466 nm for 3
(R =C6H4OMe-4), consistent with the electrochemical finding
(15) (a) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996,
77, 3865. (b) Adamo, C.; Barone, V. J. Chem. Phys. 1999, 110, 6158.
(16) Wong, C.-Y.; Man, W.-L.; Wang, C.; Kwong, H.-L.; Wong,
W.-Y.; Lau, T.-C. Organometallics 2008, 27, 324.
€
(14) Wong, C.-Y.; Che, C.-M.; Chan, M. C. W.; Han, J.; Leung, K.-H.;
Phillips, D. L.; Wong, K.-Y.; Zhu, N. J. Am. Chem. Soc. 2005, 127, 13997.
(17) (a) Frenking, G.; Frohlich, N. Chem. Rev. 2000, 100, 717.
(b) Dapprich, S.; Frenking, G. J. Phys. Chem. 1995, 99, 9352.

Article
Organometallics, Vol. 28, No. 19, 2009 5659
Table 3. HOMO and LUMO Compositions of Complexes 1, 3, and [([9]aneS3)(phen)Ru(t-BuNtC)]2þ
% composition
molecular
orbital
HOMO-LUMO
gap/eV
complex
energy/eV
Ru
CtCR/t-BuNtC
phen
[9]aneS3
1, [([9]aneS3)(phen)Ru(CtCPh)]þ
3, [([9]aneS3)(phen)Ru(CtCC6H4OMe-4)]þ
[([9]aneS3)(phen)Ru(t-BuNtC)]2þ
HOMO
LUMO
HOMO
LUMO
HOMO
LUMO
-7.387
-4.650
-6.969
-4.597
-12.187
-7.612
2.737
2.372
4.576
25.38
9.54
15.93
9.69
47.94
9.03
65.15
1.51
77.07
1.54
5.32
1.18
3.59
84.20
2.72
83.99
31.72
85.02
5.88
4.75
4.28
4.78
15.02
4.77
Table 4. Charge Decomposition Analysis (CDA) for the [([9]aneS3)(phen)Ru]2þ-L Interaction
L f M
donation (d)
M f L
back-donation (b)
L
b/d
repulsion (r)
residue (Δ)
-CtCPh (1)
1.774
1.793
1.266
0.102
0.096
0.309
0.057
0.054
0.244
-0.609
-0.604
-0.637
-0.038
-0.038
-0.010
-CtCC6H4OMe-4 (3)
t-BuNtC
Figure 3. Optimized structure and HOMO and LUMO sur-
faces for complex 1 using the PBE1PBE functional (hydrogens
are omitted for clarity, surface isovalue = 0.04 au).
Dewar-Chatt-Duncanson donor-acceptor model, as in
the case for model complexes trans-[Ru(NH3)4(CtCAr)2]
and trans-[Ru(PH3)4(CtCAr)2].14 The ratio of the values for
[([9]aneS3)(phen)Ru]2þ
f
-CtCPh back-donation (b) and
-CtCPh f [([9]aneS3)(phen)Ru]2þ donation (d), b/d, are
0.054-0.057, suggesting that the acetylide ligand is overall
an electron donor (b/d ,1). The smaller b/d ratio for 1 and 3
compared with [([9]aneS3)(phen)Ru(t-BuNtC)]2þ (b/d =
0.244) is reasonable since acetylide is charged, whereas
isocyanide is neutral. This is also consistent with the above
spectroscopic investigation suggesting that acetylide is a
greater σ-donor and weaker π-acceptor than isocyanide.
Defining the direction along the Ru-C as the z-axis and
the Ru-N as the x- and y-directions in the fully optimized
gas-phase structure for 1, it is noted that the plane of the
phenyl ring is not coplanar with the xz- or yz-planes: the
dihedral angle between the N1-Ru-Cγ and Ru-Cγ-C0
planes as defined in Figure 4 is -52.6°. Moreover, the π-
system of the -CtCPh ligand is found to be interacting with
a dxz þ dyz hybridized orbital of Ru(II) (Figure 3). A relaxed
potential energy surface scan as a function of the dihedral
angle for 1 was performed in order to gain further insight into
the conformational landscape. In the relaxed potential en-
ergy surface scan calculations, the dihedral angle was rotated
through 180° with 10° resolution and with geometry optimi-
zation at each step (rotation through 360° is not necessary
since the -CtCPh has a C2v symmetry). Figure 4 depicts the
plot of energy as a function of the dihedral angle, and the
rotational barrier for 1 is found to be 0.53 kcal mol-1. It is
noted that (1) points with the dihedral angles of ca. 0° and 90°
in the plot are not local minima and (2) the energy of 1
Figure 4. Plot of energy and shortest HPh H[9]aneS3 distance
3 3 3
as a function of dihedral angle between the Ru-Cγ-O and
N(1)-Ru-Cγ planes for complex 1 (calculated in steps of 10°;
energies are relative to the lowest-energy optimized structure).
increases with decreasing HPh H[9]aneS3 distance (the
3 3 3
shortest). These reflect that the Ru-C π-interaction in 1 is
not strong enough to lock the rotational motion of the
acetylide, and the rotational barrier for 1 is dominated by
intramolecular steric factors.
In conclusion, we have demonstrated that the dπ(RuII) f
π*(phen) MLCT absorption and emission energies for [([9]-
aneS3)(phen)Ru(CtCR)]þ are significantly red-shifted com-
pared with their isocyanide analogue. This suggests that
manipulation of Ru-C interactions is an effective way to
modulate the photophysical properties of the [([9]aneS3)-
(phen)RuL]nþ luminophore (L=carbon-rich organic moiety).
The Ru-C bonding interaction in complexes 1-3 has also
been probed by structural and theoretical methods, which
reveals that the Ru-C π-interaction is weak and cannot lock
the rotational motion of the acetylide ligand effectively.
Experimental Section
General Procedures. All reactions were performed under an
argon atmosphere using standard Schlenk techniques unless
otherwise stated. All reagents were used as received, and solvents
were purified by standard methods. [([9]aneS3)(phen)RuCl](PF6)

5660 Organometallics, Vol. 28, No. 19, 2009
Wong et al.
was prepared according to literature procedures.13 1H and
13C{1H} NMR spectra were recorded on Bruker 400 DRX
FT-NMR spectrometers. Peak positions were calibrated with
solvent residue peaks as internal standard. Electrospray mass
spectrometry was performed on a PE-SCIEX API 3000 triple
quadrupole mass spectrometer. Infrared spectra were recorded
as KBr plates on a Perkin-Elmer FTIR-1600 spectrophot-
ometer. UV-visible spectra were recorded on a Hewlett-Pack-
ard HP8452A diode array spectrophotometer interfaced with an
IBM-compatible PC. Elemental analyses were done on an
Elementar Vario EL analyzer. Cyclic voltammetry was per-
formed with a CH Instrument model 600C series electrochemi-
cal analyzer/workstation. The glassy-carbon electrode was
polished with 0.05 μm alumina on a microcloth and rinsed with
acetonitrile before use. An Ag/AgNO3 (0.1 M in CH3CN)
electrode was used as reference electrode. All solutions were
degassed with argon before experiments. E1/2 values are the
average of the cathodic and anodic peak potentials for the
oxidative and reductive waves. The E1/2 value of the ferroce-
nium/ferrocene couple (Cp2Feþ/0) measured in the same solu-
tion was used as an internal reference.
was solved and refined using full-matrix least-squares based
on F2 with the programs SHELXS-97 and SHELXL-9719
within WinGX.20 The Ru and many non-H atoms were located
according to the direct methods. The positions of the other non-
hydrogen atoms were found after successful refinement by full-
matrix least-squares using the program SHELXL-97. A highly
disordered solvent molecule was found to be present in the
crystal. Since the disordered solvent could not be modeled
reasonably, the SQUEEZE technique in PLATON was ap-
3
plied.21 A void volume of 222 A was calculated to contain
˚
30 electrons per unit cell. In the final stage of least-squares
refinement, all non-hydrogen atoms were refined anisotropi-
cally. The positions of H atoms were calculated based on a riding
mode with thermal parameters equal to 1.2 times that of the
associated C atoms.
Computational Methodology. DFT calculations were perfor-
.
med on complexes 1, 3, and [([9]aneS3)(phen)Ru(t-BuNtC)]2þ
Their electronic ground states were optimized without symme-
try constraints using the density functional PBE1PBE,15 which
is a hybrid of the Perdew, Burke, and Ernzerhof exchange and
correlation functional and 25% HF exchange. The Stuttgart
small core relativistic effective core potentials were employed for
Ru atoms with their accompanying basis sets.22 The 6-31G*
basis set was employed for C, H, N, and S atoms.23 Tight SCF
convergence (10-8 au) was used for all calculations. The nature
of the Ru-C bonds was examined using charge decomposition
analysis (CDA).17 All the DFT calculations were performed
using the Gaussian 03 program package (revision D.01)24 while
CDA was performed with the QMForge program.25
[([9]aneS3)(phen)RuCtCR](PF6), 1-3(PF6). Excess HCtCR
(0.60 mmol) was added to a methanolic solution (30 mL)
containing [([9]aneS3)(phen)RuCl](PF6) (0.20 mmol) and
KOH (2 mmol). After refluxing for 12 h, the reaction mixture
was cooled and precipitated by addition of a saturated metha-
nolic solution of NH4PF6 (5 mL). The orange precipitates were
washed with diethyl ether and dried under vacuum. The solid
was then recrystallized by slow diffusion of Et2O into an
acetonitrile or acetone solution to give bright orange crystals.
Complex 1(PF6) (R = Ph):. yield 0.12 g, 85%. Anal. Calcd for
C26H25S3N2RuPF6: C, 44.07; H, 3.56; N, 3.96. Found: C, 44.01;
Acknowledgment. The work described in this paper
was supported by grants from the Hong Kong Research
Grants Council (Project No. CityU 102708) and City Uni-
versity of Hong Kong (Project No. 7002449). We are grate-
ful to Ka-Ho Chan for spectroscopic measurements and
Dr. Shek-Man Yiu for X-ray diffraction data collection.
1
H, 3.61; N, 4.13. H NMR (400 MHz, CD3CN): δ 2.50-2.56,
2.60-2.79, 2.94-3.10 (m, 12H, [9]aneS3); 6.79 (d, J = 7.2 Hz,
2H, Ph); 6.89-7.02 (m, 3H, Ph); 7.87 (dd, 2H, J = 8.0, 5.0 Hz,
phen); 8.15 (s, 2H, phen); 8.60 (dd, 2H, J = 8.0, 1.2 Hz, phen);
9.25 (dd, 2H, J = 5.0, 1.2 Hz, phen). 13C NMR (100 MHz,
CD3CN): δ 32.6, 32.9, 36.0 ([9]aneS3); 106.7, 116.9 (CR and Cβ);
125.2, 126.5, 128.5, 128.8, 131.5, 131.7, 137.1, 139.4, 148.0, 153.6
(Ph and phen). IR (KBr, cm-1): νCtC = 2085, νP-F = 837. ESI-
MS: m/z 562 [Mþ].
Supporting Information Available: Crystallographic informa-
tion files (CIF) for 1(PF6); optimized geometries for 1, 3, and
[([9]aneS3)(phen)Ru(t-BuNtC)]2þ. This material is available
free of charge via the Internet at http://pubs.acs.org.
Complex 2(PF6) (R = C6H4Me-4):. yield 0.13 g, 90%. Anal.
Calcd for C27H27S3N2RuPF6: C, 44.88; H, 3.77; N, 3.88. Found: C,
44.67; H, 3.92; N, 3.80. 1H NMR (400 MHz, CD3CN): δ 2.15 (s,
3H, Me); 2.50-2.55, 2.60-2.78, 2.93-3.09 (m, 12H, [9]aneS3);
6.68 (d, J = 8.0 Hz, 2H, C6H4); 6.81 (d, J = 8.0 Hz, 2H, C6H4);
7.86 (dd, 2H, J = 8.0, 5.2 Hz, phen); 8.14 (s, 2H, phen); 8.60 (dd,
2H, J = 8.0, 1.2 Hz, phen); 9.24 (dd, 2H, J = 5.2, 1.2 Hz, phen).
13C NMR (100 MHz, CD3CN): δ 21.1 (Me); 32.6, 32.9, 36.0
([9]aneS3); 106.5, 114.9 (CR and Cβ); 126.5, 126.7, 128.5, 129.4,
131.5, 131.6, 134.8, 137.1, 148.0, 153.5 (C6H4 and phen). IR (KBr,
cm-1): νCtC = 2083, νP-F = 837. ESI-MS: m/z 576 [Mþ].
Complex 3(PF6) (R = C6H4OMe-4):. yield 0.13 g, 88%. Anal.
Calcd for C27H27S3N2ORuPF6: C, 43.90; H, 3.69; N, 3.79.
Found: C, 43.81; H, 3.58; N, 3.82. 1H NMR (400 MHz,
(19) Sheldrick, G. M. SHELXS-97 and SHELXL-97, Program for
€
Crystal Structure Solution and Refinements; University of Gottingen:
Germany, 1997.
(20) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(21) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool;
Utrecht University: Utrecht, The Netherlands, 2001.
(22) Andrae, D.; Haeussermann, U.; Dolg, M.; Stoll, H.; Preuss, H.
Theor. Chim. Acta 1990, 77, 123.
(23) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56,
2257.
(24) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakr-
zewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.;
Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03, revision D.01; Gaussian, Inc.:
Wallingford, CT, 2004.
CD3CN):
δ 2.48-2.55, 2.59-2.78, 2.93-3.10 (m, 12H,
[9]aneS3); 3.62 (s, 3H, OMe); 6.55 (d, J = 8.8 Hz, 2H, C6H4);
6.73 (d, J = 8.8 Hz, 2H, C6H4); 7.84 (dd, 2H, J = 8.4, 5.2 Hz,
phen); 8.10 (s, 2H, phen); 8.57 (dd, 2H, J = 8.4, 1.2 Hz, phen);
9.24 (dd, 2H, J = 5.2, 1.2 Hz, phen). 13C NMR (100 MHz,
CD3CN): δ 32.6, 32.9, 36.0 ([9]aneS3); 55.7 (OMe); 105.9, 113.0
(CR and Cβ); 114.3, 122.2, 126.5, 128.5, 131.4, 132.8, 137.0,
148.0, 153.5, 157.7 (C6H4 and phen). IR (KBr, cm-1): νCtC
=
2081, νP-F = 839. ESI-MS: m/z 592 [Mþ].
X-ray Crystallography. X-ray diffraction data for 1(PF6) were
collected on an Oxford Diffraction Gemini S Ultra X-ray single-
˚
crystal diffractometer with Mo KR radiation (λ = 0.71073 A) at
100 K. The data were processed using CrysAlis.18 The structure
(25) (a) Tenderholt, A. L. QMForge, Version 2.1, http://qmforge.
sourceforge.net. QMForge depends heavily on cclib, which does all the
parsing and analysis. (b) O'Boyle, N. M.; Tenderholt, A. L.; Langner, K. M. J.
Comput. Chem. 2008, 29, 839.
(18) CrysAlis, Oxford Diffraction Ltd., Version 1.171.31.8, 2007.