Solution and solid-state spectroscopic characterization of chloro dimethylsulfoxide polythioether ruthenium(II) complexes, complemented with DFT calculations in the gas phase

Article abstract of DOI:10.1080/00958972.2013.770846

Several ruthenium(II)-chloro-dimethylsulfoxide complexes with formulae [RuCL²(DMSO)(k3-L¹)] or [RuCl(DMSO)(k4-L²)]+, where L¹ = [9]aneS3 (2) or ttbt (5) and L² = [12]aneS4 (3), [1₄]aneS4 (4) or [1₄]aneN4 (6), have been synthesized from cis,fac-[RuCL²(S-DMSO)₃(O-DMSO)] (1) and the respective macrocycle. They were spectroscopically characterized by FT-IR, FT-Raman, NMR, and UV/Vis. Particular attention was given to fac-[RuCL ²(DMSO)(k3-ttbt)] (5), the first octahedral complex of ttbt, which was also studied by DFT calculations. The behavior of the complexes in coordinating solvents water, acetonitrile, and dimethylsulfoxide was studied to understand their reactivity and predict the resulting ions formed in solution. The role of the counter ion (Cl- vs. PF- 6 ) was also evaluated. The results indicate that the chosen macrocycle, the counter-ion, and the solvent have a direct impact on the chemical species formed in solution.

Full text of DOI:10.1080/00958972.2013.770846

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Solution and solid-state spectroscopic
characterization of chloro
dimethylsulfoxide polythioether
ruthenium(II) complexes,
complemented with DFT calculations in
the gas phase
João Madureira a b & Teresa M. Santos a
a Departamento de Química e CICECO , Universidade de Aveiro ,
Aveiro , Portugal
b Department of Chemistry , Virginia Commonwealth University ,
Richmond , VA , USA
Accepted author version posted online: 29 Jan 2013.Published
online: 15 Mar 2013.
To cite this article: João Madureira & Teresa M. Santos (2013) Solution and solid-state
spectroscopic characterization of chloro dimethylsulfoxide polythioether ruthenium(II) complexes,
complemented with DFT calculations in the gas phase, Journal of Coordination Chemistry, 66:5,
881-903, DOI: 10.1080/00958972.2013.770846
To link to this article: http://dx.doi.org/10.1080/00958972.2013.770846
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Journal of Coordination Chemistry
Vol. 66, No. 5, 10 March 2013, 881–903
Solution and solid-state spectroscopic characterization of
chloro dimethylsulfoxide polythioether ruthenium(II)
complexes, complemented with DFT calculations in the gas
phase
JOÃO MADUREIRA†‡* and TERESA M. SANTOS†
†Departamento de Química e CICECO, Universidade de Aveiro, Aveiro, Portugal;
‡Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
(Received 2 August 2012; in final form 29 November 2012)
Several ruthenium(II)-chloro-dimethylsulfoxide complexes with formulae [RuCl2(DMSO)(k3-L1)] or
[RuCl(DMSO)(k4-L2)]+, where L1 = [9]aneS3 (2) or ttbt (5) and L2 = [12]aneS4 (3), [14]aneS4 (4) or
[14]aneN4 (6), have been synthesized from cis,fac-[RuCl2(S-DMSO)3(O-DMSO)] (1) and the
respective macrocycle. They were spectroscopically characterized by FT-IR, FT-Raman, NMR, and
UV/Vis. Particular attention was given to fac-[RuCl2(DMSO)(k3-ttbt)] (5), the first octahedral
complex of ttbt, which was also studied by DFT calculations. The behavior of the complexes in
coordinating solvents water, acetonitrile, and dimethylsulfoxide was studied to understand their
reactivity and predict the resulting ions formed in solution. The role of the counter ion (ClÀ vs.
PFÀ6 ) was also evaluated. The results indicate that the chosen macrocycle, the counter-ion, and the
solvent have a direct impact on the chemical species formed in solution.
keywords: Ruthenium; Crown thioethers; Counter-ion; Solvolysis; Molecular modeling
1. Introduction
Complexes with macrocyclic ligands represent classic coordination chemistry. Among
them, crown thioethers became increasingly popular, starting in the late 1980s [1–6]. They
are more commonly used as ligands with second and third transition elements series, but
several complexes of the first series of transition elements were already produced [1,7,8].
They stabilize metal centers with high electron density, even for uncommon and typically
unstable oxidation states like Ag(II), Au(II), Rh(II), or Pd(III) [2,9].
One, 1,4,7-trithiacyclononane ([9]aneS3), became the object of many studies in
coordination chemistry because of its unique properties among polythioethers, with its
lower energy conformations fully or partially endodentate [10,11]. The very high chemical
robustness of [9]aneS3 complexes also permitted imaging compounds (99mTc) [12] or
γ-emitting isotopes (186,188Re) [13] to be developed and explored in nuclear medicine.
Recently, Ru(II) and Rh(III) complexes with [9]aneS3 have also been tested as anti-tumor
candidates [14].
*Corresponding author. Email: jlmadureira@vcu.edu
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online Ó 2013 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2013.770846

2
J. Madureira and T.M. Santos
Besides [9]aneS3, other macrocycles used in coordination compounds presented in this
study include 1,4,7,10-tetrathiacyclododecane ([12]aneS4), 1,4,8,11-tetrathiacyclotetrade-
cane ([14]aneS4), 3,6,9,14-tetrathia-bicyclo[9.2.1]tetradeca-1(13),11-diene (ttbt), and
1,4,8,11-tetraazacyclotetradecane ([14]aneN4) (scheme 1). With the exception of ttbt, coor-
dination chemistry of these crown thioethers has been extensively studied [15–18]. Ttbt
has only been used for a few coordination compounds, with Cu(II), Ag(I), Pd(II) and Pt
(II), [16,19–22]. Furthermore, while many of the more common crown thioethers have
been studied by theoretical means [11,23,24], this is not the case with ttbt or its
complexes. We here present some of our DFT results with ttbt and its first ruthenium and
octahedral complex, [RuCl2(DMSO)(k3-ttbt)] and compare them with the available X-ray
data [25].
Ruthenium–halo–sulfoxide complexes have been studied during the last decades in the
area of medicinal chemistry, mainly for anticancer activity [25,26]. Sulfoxides increase
both lipophilic and hydrophilic properties of metal drugs, resulting in less toxic deriva-
tives, compared with their parent chloro-complexes, while keeping their chemotherapeutic
activity [27].
Only a few ruthenium polythioether complexes with DMSO and chloro ligands are
known [15,28–31]. These compounds are of interest as adequate precursors for polypyri-
dyl–polythioether complexes, but also in themselves, since they might have interesting
properties that result from the combination of the increased stability imposed by crown
thioethers and the lipophilicity and aqueous solubility of DMSO–ruthenium complexes
[30,32,33].
In this article, we present some of our work on chloro dimethylsulfoxide polythioether
ruthenium(II) complexes, some previously published and other new, that belong to a class
of compounds that has been barely studied. Besides the spectroscopic characterization
Scheme 1. Macrocycles studied in this work.

Ruthenium macrocycles
3
(UV/Vis, FTIR, Raman and NMR), we also include reactivity tests of the compounds in
aqueous and organic media with coordination ability (CH3CN, DMSO) and perform an
analysis of the counter ion role (ClÀ vs. PFÀ6 ). Wherever necessary, the deuterated DMSO
derivatives, same as their bromo and iodo analogs, have been synthesized and character-
ized to ensure unambiguous assignments in the solid state.
2. Results and discussion
2.1. Synthesis of complexes
Six of the seven complexes discussed in this article are indicated in scheme 2, along with
their preparation methodology; the proposed structures are consistent with NMR, FT-IR,
and EA or ESI-MS characterization. Compounds 1–4 were prepared with small varia-
tions from the literature procedures [15,28,30,34]. The deuterated derivative of 1,
cis-[RuCl2(DMSO-d6)4], 1a, was used in the synthesis of fac-[RuCl2(DMSO-d6)([9]
aneS3)], 2a, and cis-[RuCl(DMSO-d6)([12]aneS4)]Cl, 3a, combining it with the respective
macrocycles. Compounds fac-[RuBr2(DMSO)([9]aneS3)], 2b, and fac-[RuI2(DMSO)([9]
aneS3)], 2c, were obtained by solubilizing 2 in water in the presence of an excess of NaBr
or CsI, respectively.
While 1–4 were prepared in good yields, the synthesis of [RuCl2(DMSO)(k3-ttbt)], 5,
where ttbt is 3,6,9,14-tetrathia-bicyclo[9.2.1]tetradeca-1(13),11-diene (scheme 1), gave a
lower yield (25%) and required a purification step comprising an extraction in chloroform.
The hypothetically tetradentate, complex 5, shows ttbt in a tri-coordinated form. Such a
coordination mode can be explained by the stiffness imposed by the thiophene ring in the
macrocyclic skeleton [21,22,35]. The formula assigned to 5 is consistent with solid state
(FT-IR and EA) and solution (NMR) data [36]. Both NMR and infrared data confirm sul-
fur coordination of DMSO. The neutral charge formula is also consistent with the very
low observed solubility of the formed complex in almost all common organic solvents.
Theoretical calculations at the DFT level (see Sections 2.5 and 3.2) indicate a preference
for fac coordination that was recently confirmed by a single crystal X-ray structure
[25,37].
Although ttbt has been known for almost 25 years [20], a detailed literature survey indi-
cates that 5 is the only known coordination compound with octahedral geometry. In fact, 5
was only presented in the PhD thesis of this study’s first author and has been made
recently available electronically [37] in the PhD thesis of Dr E.L.S. Cheu [25].
We also used the polyamine analog of [14]aneS4 to prepare [RuCl(DMSO)([14]aneN4)]
PF6, 6, which was isolated as a light yellow solid with a yield of 44%. Ru(II) complexes
with un-oxidized polyamines are not so common [38], since they tend to oxidize to their
polyimine analogs. The synthesis of 6 presents the reproducibility problems already seen
in other ruthenium reactions with [14]aneN4 [39–43]. A gradual darkening and color
change to green can be seen after some weeks even in the solid state. Since NMR
indicates that a diamagnetic complex is still in solution, it seems plausible that oxidative
dehydrogenation of the polyamine catalyzed by the coordination metal ion occurs. This is
a common phenomenon with aliphatic polyamines, particularly when coordinated to group
VIII metal ions [40,43]. Probably the presence of DMSO in the coordination sphere slows
down the reaction, due to its stabilization of Ru(II).

4
J. Madureira and T.M. Santos
Scheme 2. Synthesis of 1–6.
Finally, [RuCl(CH3CN)(DMSO)([9]aneS3)]PF6, 7, was prepared from 2 and NH4PF6 in
CH3CN (see Sections 2.6 and 3.3), which is a relatively rare example of a {M([9]aneS3)}
octahedral complex with different monodentate ligands on all the remaining coordination
positions [44,45].
Complex 1 is prepared in pure DMSO. Because of its high viscosity, the solvent tends
to remain attached to the compound even after washing with different solvents and a
variable amount of free DMSO is always present in the precursor and the remaining com-
plexes. To minimize the DMSO excess and the possibility that [RuCl(DMSO)2([9]aneS3)]+
competes with [RuCl2(DMSO)([9]aneS3)], 2, during its preparation, the complex was
recrystallized in ethanol.

Ruthenium macrocycles
5
In 2–7, only S-DMSO coordination is observed. This is the most common coordination
mode in Ru(II) compounds, as shown by structural data and theoretical calculations
[46–48]. Such a preference results from the high electronic density of Ru(II), adequate
orbitals for π bonding and absence of, or just moderate, trans π-acceptor competition
(chloride acts as a π-donor, while thioethers are also π-acceptors, although considerably
weaker than DMSO) [28–30,49].
2.2. Infrared absorption and Raman diffusion spectroscopy
Assignment of the coordination sphere vibration modes in ruthenium(II) complexes, like in
any other metal ion with small force constants, is normally not made without some degree
of uncertainty. Stretching and bending modes related with the metal ion and the binding
positions occur on the lower energy detection limit of many infrared devices. At such
frequencies, there is also loss of transparency of common materials for pellet preparation
(CsI and, particularly, KBr). Furthermore, assignments become complicated because metal-
ligand and ligand vibration modes typically overlap, the same as combination modes or
crystal packing associated bands.
In order to help the assignments, deuterated homologues of 1–3 and halogenated
derivatives of 2 were prepared. Their infrared and Raman spectra were compared with
their equivalents of [Ru([9]aneS3)2](PF6)2, [RuCl(CH3CN)([12]aneS4)]PF6, and [Ru
(CH3CN)2([12]aneS4)](PF6)2, the same as for their respective macrocycles.
All complexes show vibrational bands at wave numbers that are typical of Ru–S
(DMSO) and Ru–halogen bond stretches. Compounds 2–5 and 7 also show bands assigned
to Ru–S stretching modes from the crown thioethers (table 1).
Based on the observed shifts of the characteristic sulfoxide stretching, it was also
possible to differentiate between sulfur-bonded and oxygen-bonded DMSO, since linkage
isomers show different frequency ranges.
Combined use of absorption (IR) and diffusion (Raman) vibrational techniques allow
methyl νC–H and νS=O stretching modes in DMSO to be distinguished from the methylene
νC–H and δC–H modes in the macrocycles, respectively.
2.2.1. Metal-ligand stretching and bending mode. The fac-[MS3X2Y] complexes with
a pseudo-octahedral environment around the central M belong to the Cs point group with
three νM–S, two νM–X and one νM–Y stretching modes, active in both the infrared and
Raman spectra. The compounds cis-[MN4/S4XY] also belong to the Cs point group and
present four νM–N/S vibrations, one νM–X and one νM–Y, all infrared and Raman active [50].
In polyamine or polythioether macrocycle complexes several conformations might coexist
at r.t., with the macrocycle imposing distortions to the pseudo-octahedral geometries,
resulting in an increment in the number of bands.
Assignments of the vibrational bands at 500–200 cmÀ1 for 1–7 are presented in table 1.
A more detailed analysis was performed for 1–3 based on the comparison with their
DMSO-d6 analogs (1a, 2a, 3a), and the bromo (2b) and iodo (2c) forms of 2 (see
Section 3.3 and tables S1–S3 in Supplementary material).
Stretching bands for Ru–S (DMSO) and Ru–S (thioether) show similar intensity in the
Raman spectra, but the first type is much more intense in the infrared (figure 1). The
Ru–S (DMSO) stretch is seen at 420–430 cmÀ1, sometimes with a less intense one near

6
J. Madureira and T.M. Santos
Table 1. Infrared and Raman vibrational mode assignment (500–200 cmÀ1) for 1–7.
νRu–S
(DMSO)
νRu–O
(DMSO)
νRu–Smacro
δC-S–O
IR
νRu–N
IR
νRu–Cl
IR R
Complexes
IR
R
IR
R
IR
R
R
R
[RuCl2(DMSO)3(DMSO)], 1
448
425
448 483 476 389 384
424
264sh 255
246b
[RuCl2(DMSO)([9]aneS3)], 2
[RuCl(DMSO)([12]aneS4)]Cl, 3
493
456
493 456
458 421
377 377
421
274d 276
261
271
263
272
460s 455 422
447h 448
421
377 380d
436
466
439
439
[RuCl(DMSO)([14]aneS4)]PF6, 4
[RuCl2(DMSO)(k3-ttbt)], 5
428
379
273
488a 488 430
468sh 468
442
432
444
428
378 380
379 397
377 377
277
264b
282
[RuCl(DMSO)([14]aneN4)]PF6, 6
253 280
239
224 247
424sh
496 430
460b 461
496 495
[RuCl(MeCN)(DMSO)([9]aneS3)]PF6, 7 493
248
[Ru(MeCN)3([9]aneS3)](PF6)2
[Ru([9]anoS3)2](PF6)2
200
467d 466d
425b 432
412b 412b
495
471
461
471
458
430
aEventually from ttbt (491 cmÀ1).
bProbably ν5 of PF6À, observed in TBA-PF6 and TlPF6 Raman spectra at 418 and 414 cmÀ1, respectively.
Notes: b – broad; d – doublet; and sh – shoulder.
Figure 1. Infrared (top) and Raman spectra (bottom) of the vibration modes on the 500–200 cmÀ1 range for (a)
fac-[RuCl2(DMSO)([9]aneS3)], 2 and (b) cis-[RuCl(DMSO)([12]aneS4)]Cl, 3.

Ruthenium macrocycles
7
450 cmÀ1. Ru–S (thioether) stretching occurs between 420 and 490 cmÀ1 with two to four
bands.
Complexes 1–5 and 7 present νRu–Cl bands between 246 and 277 cmÀ1, while [RuCl
(DMSO)([14]aneN4)]PF6, 6, shows two weak bands at 258 and 280 cmÀ1, in the infrared,
and two at 266 and 282 cmÀ1, in the Raman spectra. Previously published literature data
on Ru–Cl stretches covers the range 240–275 cmÀ1 [39,51,52]. X-ray data show that
Ru–Cl bonds where Cl is trans to polythioethers or DMSO are significantly longer than
expected for a pure σ donor [53], indicating π back donation. A slight increase in the
Ru–Cl wavenumber is expected for 6, since no π back donation is present with the amine
macrocycle.
Ru–N stretching modes are expected below 250 cmÀ1 and only a few of such vibration
modes are found in the literature. Because of this, the values of νRu–N presented in table 1
for 6 and 7 should be considered as tentative assignments.
2.2.2. Other characteristic vibration modes. The S=O stretching is the most charac-
teristic vibration mode of DMSO. As free solvent, it appears at 1055 cmÀ1. Metal
coordination through S increases the double bond character of sulfoxide, shifting the
band to higher wave numbers. When metal binding occurs as O-DMSO, the band
moves to lower energy, since the zwitterionic form is favored (single bond). Since all
complexes show a strong band or a doublet near 1100 cmÀ1 [46], an S-DMSO coordi-
nation mode is assigned: 2 (1088 cmÀ1), 3 (1092 and 1077 cmÀ1), 4 (1084 cmÀ1), 5
(1088 cmÀ1), 6 (1081 cmÀ1) and 7 (1100 and 1092 cmÀ1) [54]. Complex 1, with a
crystal structure that establishes the presence of three coordinated S-DMSO and one
O-DMSO, shows vibrations in both regions: 1107 and 1086 cmÀ1 (S-DMSO) and
925 cmÀ1 (O-DMSO) [53]. Another characteristic vibration of DMSO is δC–S–O, seen
for 1–7 at 377–389 cmÀ1
.
Acetonitrile coordination to the metal ion is signaled in the infrared and Raman spectra
of 7 by two weak to medium intensity bands at 2314 and 2286 cmÀ1, being more intense
in the Raman. The observed values agree well with data for ruthenium(II)–acetonitrile–
polythioethers complexes [15,28,30].
2.3. Nuclear magnetic resonance spectroscopy
1H NMR spectra of the compounds present an aliphatic region with a series of multiplets
that correspond to macrocycle methylene groups and sharp singlets from methyl protons of
DMSO (1–7) and CH3CN (7). All prepared complexes show singlets between 3.0 and
3.5 ppm, in different solvents, assigned to S-coordination of DMSO. This one is character-
ized by a deviation to weak field of approximately 1 ppm by comparison with the solvent
(2.55 ppm in DMSO-d6), while the O-coordination mode causes only a slight shift to weak
field (ca. 0.1 ppm) [55]. Two slightly different environments, separated by 0.02 to
0.07 ppm, and equally intense can be seen in the complexes. Since it is highly improbable
that all macrocycles show two macrocycle conformations in equilibrium with the same 1 :
1 relative abundance at r.t., they probably result from alternative environments of each
methyl in DMSO. While the vibrations of DMSO with a major rotation component around
Ru–S or C–S (methyl rotation) are typically free at r.t., they correspond to small displace-
ments from their equilibrium positions and not full rotation around the bond axis. For that,

8
J. Madureira and T.M. Santos
much more energy is required to surpass the energy barriers that result from loss of
stabilizing interactions between DMSO and other parts of the molecule, and possible repul-
sion that occurs for certain rotation angles. Another piece of information that supports this
interpretation is the fact that 3 shows two environments in CH3CN, but only one in D2O.
Since there are no signs of exchange of DMSO by CH3CN or water, the differences
observed among the solvents might come from their different ability to establish
interactions with coordinated DMSO that, in the case of water, might override the internal
interactions that exist in the complex.
Complex 2 also presents a single DMSO environment in CD3NO2 (figure S1), in
contrast to other complexes that show two environments in this solvent. Nevertheless, in
the solid state the CP-MAS and HP Dec-MAS NMR spectra show two methyl environ-
ments at 42.3 ppm (J = 83 Hz) and 46.9 ppm (J = 68 Hz), as seen in figure 2, as a result of
structure rigidification caused by packing. The values appear in a range similar to other Ru
(II)–S-DMSO complexes [55]. While 13C CP-MAS shows only two environments for free
[9]aneS3, at 21.5 and 27.2 ppm, coordination causes loss of symmetry and shifts the chem-
ical environments to weak field, with a series of multiplets between 26 and 41 ppm
assigned to CH2–S [30,56]. It was not possible to solve these environments in the HP
Dec-MAS spectrum of 2, even with a relaxation time of up to 120 s, acquisition time of
up to 48 h, and proton decoupling in the power limit range. Such behavior comes from dif-
ferent relaxation times of the different environments, which will be emphasized if two
alternative conformations of [9]aneS3 coexist at r.t. in the solid state. Nine different 13C
environments for [9]aneS3 suggest two conformers: a more symmetric one with Cs symme-
try (three environments) and a C1 form, where all six carbons are magnetically different.
Complex 5, [RuCl2(DMSO)(k3-ttbt)], is almost insoluble in common organic solvents.
1
In DMSO, where it is moderately soluble, a fast ligand exchange can be seen. The H
NMR was acquired in CDCl3 but due to the very low solubility, it was more difficult to
analyze and prevented the acquisition of a NOESY spectrum. The aliphatic region of the
complex shows a large number of doublets (figure 3). Besides a major set of peaks,
weaker ones are also clearly seen (ca. 1 : 5). Since purity of the compound has been estab-
lished for several samples and further purification did not change the spectrum, it seems
that several forms of the complex coexist. Two equally intense signals at 7.12 ppm and
7.06 ppm assigned to the thiophene protons could be seen, in contrast to the free macrocy-
Figure 2. 13C MAS spectra of fac-[RuCl2(DMSO)([9]aneS3)], 2. (a) HP Dec-MAS. (b) CP-MAS.

Ruthenium macrocycles
9
Figure 3. 1H NMR of mer-[RuCl2(DMSO)(k3-ttbt)], 5, in CDCl3. (a) Left – aliphatic protons of ttbt and DMSO.
(b) Right – aromatic protons of the thiophene component.
cle that shows a single environment at 6.92 ppm, as a result of fast exchange between ttbt
conformers. In DMSO-d6, two new environments with the same intensity are seen at 7.18
and 6.98 ppm, assigned to the thiophene unit protons. Furthermore, there is an increase in
free DMSO environments.
The highest known coordination number of ttbt macrocycle is three, despite its four
available coordination positions. In 5, the two environments for the thiophene unit and the
large number of methylene environments, for both major and minor sets of signals, support
an asymmetrically coordinated crown thioether that is rigid at r.t.
While Pd(II)/Pt(II)–ttbt complexes are flexible enough to permit conformer interconver-
sion or fluxion between available positions for coordination in k3 systems [21,22], a typical
octahedral coordination metal ion, like Ru(II), results in more rigid crown thioether
coordination structures, because the energy barriers between ttbt conformers are expected
to increase.
1
The more probable explanation for the H NMR of 5 in CDCl3 is an asymmetrically
coordinated ttbt with more than one geometric isomer or conformer. To clarify this
situation, theoretical calculations were performed for 5, which are presented and discussed
in Sections 2.5 and 3.2.
The spectrum of [RuCl(DMSO)([14]aneN4)]PF6, 6, in CD3NO2 confirms the diamag-
netic nature of the complex. Besides the usual macrocycle and DMSO environments, four
weak environments can be seen between 8.0 and 8.6 ppm, assigned to amine protons.
Since the large majority of {Ru([14]aneN4)} complexes with monodentate ligands are Ru
(III), such stabilization of Ru(II) must come from the coordinated S-DMSO.
[RuCl(CH3CN)(DMSO)([9]aneS3)]PF6, 7, shows besides the polythioether and DMSO
environments, a singlet near 2.7 ppm (in acetone-d6), assigned to coordinated acetonitrile
(figure S2).
2.4. UV/Vis spectroscopy
Complexes 1–7 show absorption bands in the visible region of the spectrum with maxima
between 370 and 420 nm and colored solutions from a pale yellow to deep orange. The
upper limit is observed in complexes with the higher number of coordinated chloro groups.

10
J. Madureira and T.M. Santos
Figure 4. UV/Vis spectra of [RuX2(DMSO)([9]aneS3)] (X = Cl, Br, I) in ethanol at 20°C. (—) chloro, (- - - -),
bromo, (…) iodo.
The absorptions in the visible region have molar absorptivity coefficients below 103 MÀ1
cmÀ1. To help the assignments, the chloro, bromo, and iodo forms of 2 were prepared and
their UV/Vis spectra are represented in figure 4.
6
The electronic spectra of low-spin octahedral d complexes are expected to present two
1
1
1
1
spin allowed transitions at relatively low energy: A1g → T1g and A1g → T2g. The com-
plexes cis,fac-[RuX2(S-Me2SO)([9]aneS3)] present a much lower symmetry (actually C1).
Ignoring the chelate rings of [9]aneS3, it can be approximated to Cs. If we also consider
that the polythioether and dimethylsulfoxide electronic impact is not so different, it can be
further approximated to cis-[RuX2(S)4], with C2v punctual symmetry. These approxima-
tions are expected to hold well for the electronic spectra interpretation since the effective
symmetry depends mainly on the type of ligand atoms bonded to the metal center. The
T1g and T2g terms in Oh are split in A and B terms, and six transitions are predicted
instead of two. Despite this, only three bands are commonly seen since several show
reduced splitting: ν1 (B1 from T1g), ν2 (A2 and B2 from T1g), and ν3 (A1, A2 and B2 from
T1g). More intense charge transfer bands overlapping the d–d bands are also common.
They can be either MLCT or LMCT types (to orbitals centered on the S atoms and from
LUMO orbitals of the halogens, respectively).
The electronic spectra of 2, 2b, and 2c were convoluted with multi-Gaussians in order
to determine all transitions that might be overlapped (figures S5–S7). The cÀom1 pounds have
five regions in common with maxima at 417–480 nm (ɛ ≈ 5.0–6.7 Â 102 M cmÀ1), 352–
359 nm (ɛ ≈ 1.6–3.8 Â 102 MÀ1 cmÀ1), 308–334 nm (ɛ ≈ 3.5–6.3 Â 102 MÀ1 cmÀ1), 276–
307 nm (ɛ ≈ 7.0–12.4 Â 102 MÀ1 cmÀ1), and a last more intense band (ca. 3 Â 104 MÀ1
cmÀ1) at 208–221 nm. The first two absorptions of the spectrum (λ in nm, ɛ in 10À3 MÀ1
cmÀ1) of the related complex cis-[RuX2([14]aneS4)] appear at 430–455 (0.12–0.18) and
363–380 (0.90–1.02) [51].
The lowest energy bands are too intense to be classified as spin-forbidden transitions.
Except for the higher energy band, they are plausibly d–d transitions, in line with their
modest intensity and the wavelength evolution that follows the spectrochemical series. In
fact, increasing the π-donor strength, according to the order chloro < bromo < iodo, should
cause a gradual increase in the energy of Ru(II)-filled d orbitals and a decrease in the

Ruthenium macrocycles
11
ligand-field splitting parameter, moving transitions to red, as is typically seen in more
regular octahedral systems (t2g to eg energy gap).
The higher energy band is assigned to a MLCT transition where the acceptor orbital is
probably σ⁄C–S, as seen in other Ru(II)–[9]aneS3 complexes [57,58].
Besides these bands, complex 2c shows an extra one at 267 nm, which might have its
origin in a double excitation of d–d type, as is known to occur in other iodo complexes
[40,42,43].
Ligands trans to one another interact with the same d orbital and the combined impact of
the two ligands can be approximated to the average of the impact of each one. For the com-
plexes under study, the axial field strength is then caused by two sulfurs, while in the equato-
rial plane, it corresponds to the average of S and X field strength. Such interpretation permits
to treat the cis series as a trigonal distortion to Oh, like seen for the series trans-[RuX2(S)4].
Such distortion causes the splitting of the 1A1g → 1T1g band in 1A1g → 1Eg and 1A1g → 1A2.
1
1
The splitting of T2 is usually neglected, and a single transition corresponding to A1g
→
1T2g is expected. Higher energy bands should have charge transfer nature.
As an example, the related trans-[RuX2(S)4], where S4 = (Me-S-S-Me)2 and X = Cl or
Br, the three bands are detected ca. 21,000 cmÀ1, 29,000 cmÀ1, and above 30,000 cmÀ1
[59]. Assuming the average impact of the ligands force field trans to each other, the first
two transitions in the cis analog are predicted to occur near 25,000 and 29,000 cmÀ1
,
respectively, which is similar to our experimental results.
The trigonal model predicts four electronic transitions but has five parameters – Dq, Dt,
Ds, B, and C – where Dq is the octahedral crystal field parameter, Dt and Ds are the
tetragonal field parameters, and B and C are the relevant Racah parameters. Dt is a mea-
sure of the difference between the Dq values of equatorial and axial ligands (for details on
the model see the literature) [60]. To solve such equations it is common to consider C ≈
1
4·B and neglect the splitting of the T2g term giving an average energy for ν3 and ν4.
Since 2, 2b, and 2c have four transitions less intense than 1000 MÀ1 cmÀ1, but the last
one occurs at wavelengths below 300 nm, it is questionable that all four correspond to d-d
transitions and calculations were performed for the two hypotheses.
The equation systems were solved with Derive™ v.6.1 from Texas Instruments for the
wavelengths determined with the multi-Gaussian fitting (Origin® v.7.1). It was considered
1
1
1
1
that the order of A1g → Eg and A1g → A2 transitions is inverted by comparison with
the trans series.
Table 2. Characterization of the electronic spectra of [RuX2(DMSO)([9]aneS3)] (X = Cl, Br, I): maxima and
absorptivity obtained by multi-Gaussian fitting, crystal field and Racah parameters (all values in cmÀ1, except ɛ in
10À3
M
À1 cmÀ1).
λ [ɛ]
Dq
Ds
Dt
B
C
cis-[RuCl2(DMSO)([9]aneS3)], 2
cis-[RuBr2(DMSO)([9]aneS3)], 2b
cis-[RuI2(DMSO)([9]aneS3)], 2c
24,008 [0.65]
28,039 [0.16]
32,471 [0.63]
36,282 [0.70]
22,878 [0.50]
28,398 [0.35]
30,867 [0.35]
34,514 [1.21]
20,830 [0.67]
27,887 [0.38]
29,968 [0.58]
32,557 [1.24]
2609
539
À461
520
2079
2456
2237
476
263
À631
À807
421
385
1685
1540

12
J. Madureira and T.M. Santos
While both hypotheses give small differences on Dq values (400–600 cmÀ1) and the
right decrease in Dq: Cl > Br > I, only when considering the splitting of the third and fourth
transition, values obtained for the main Racah parameter, B, follow the expected steady
decrease in magnitude, with Cl > Br > I (table 2). Concomitantly, the magnitude of Dt
augments, indicating the increase in the difference on the field strength between sulfur and
the halogen.
2.5. Molecular modeling
Previous studies on complexes with different macrocycles have shown that DFT can
adequately modulate their structural, energetic, and conformational preferences [17,61], but
so far only a few crown thioether transition metal complexes have been studied by theoret-
ical methods [17,24,58,62]. Here, theoretical calculations at the DFT level were performed
for ttbt and fac-[RuCl2(DMSO)(ttbt)], 5, that have their geometries established in the crys-
talline solid state. Calculations for ttbt were performed first to assess the ability of different
models to mimic its experimental X-ray crystal structure (table S4) [20]. Calculated and
experimental structures are in good agreement as can be seen in figure S3 for calculations
at the B3LYP/6-311+G(2d,p) level (RMSD = 0.09 Å, heavy atoms only). The minimized
structure correctly predicts that all sulfurs are exocyclic and almost in the same plane, with
the thiophene unit almost perpendicular to it, as seen in the X-ray crystal structure.
Calculations for 5 were performed at the B3LYP/6-311+G(2d,p)/LANL08f level of
theory, where LANL08f is the relativistic core potential and corresponding triple-ζ valence
basis set of Roy et al., supplemented with a polarization f function, chosen for the metal
ion [63,64].
There are three possible sequences of bonded sulfurs for the fac isomers: Ste–Ste–Ste,
Ste–Ste–Stph, and Ste–Sthp–Ste, where Ste and Sthp stand for a thioether and a thiophene type
of sulfur, respectively. Only Ste–Ste–Stph is relevant at r.t. During optimization of these
types of structures, six different conformations of the crown thioether could be found. For
each crown thioether conformation, there are three fac geometrical isomers, according to
the positions of the monodentate ligands (plus the optical isomers, which need not be
taken into account for calculation purposes). Only one of conformations is relevant at r.t.,
with almost 100% of combined abundance. This conformation is the same observed in the
X-ray crystal structure of the optical isomer of II, previously determined by Cheu [25].
The three geometrical isomers (I–III) are represented in figure 5 [65].
After coordinate transformation of the X-ray crystal structure, to achieve the “correct”
optical isomer, its comparison with II gives a heavy-atom RMSD of 0.094 Å. Since the
lower frequency of vibration in these conformers corresponds mainly to the rotation of
DMSO along the Ru–S bond and was found to occur at 40 cmÀ1 or less, the position of
DMSO substituents should be very flexible at r.t. Neglecting such substituents significantly
improves the RMSD to 0.073 Å. These results substantiate the ability of DFT to
adequately reproduce the molecular structures of coordination compounds and mimic their
crystal structures.
The main bond lengths and angles for isomers I–III are summarized in table 3. Bond
angles of the coordination sphere show only small deviations from an octahedral geometry.
The larger deviation is on the longitudinal axis, where
Sthp–Ru–X = 171–172° (X = Cl,
DMSO), with Sthp slightly deviated to the side of its coordinated Ste neighbor. Ru–S bond
lengths are significantly influenced by the ligand in the trans position. There is a strong

Ruthenium macrocycles
13
Figure 5. DFT-minimized structures of fac-[RuCl2(DMSO)(k3-(S3,S6,S14-ttbt)], 5, isomers ([I]–[III]) and X-ray
crystal structure ([IV]) of the optical isomer of [II].
Table 3. Bond lengths (Å) and angles (°) of the isomers of fac-[RuCl2(DMSO)(ttbt)], 5.
I
II
III
X-ray25
Ru–Sthp
2.436
2.416
2.394
2.329
2.431
2.463
170.8
88.2
2.415
2.430
2.385
2.345
2.432
2.459
171.8
88.2
2.544
2.398
2.384
2.280
2.465
2.451
171.1
88.4
2.320(2)
2.375(2)
2.300(2)
2.290(2)
2.400(2)
2.430(2)
172.0
a
Ru–Ste
Ru–Ste
b
Ru–SDMSO
Ru–Clc
Ru–Cld
Sax–Ru–X
Seq–Ru–Seq
88.4
aTrans to SDMSO
bTrans to Cl.
.
cTrans to Sthp
.
dTrans to Ste; X = Cl, DMSO.

14
J. Madureira and T.M. Santos
increase in Ru–Sthp from 2.42–2.44 Å to 2.54 Å when changing from a chloro to a
DMSO, while Ru–Ste goes from 2.38–2.40 Å to 2.42–2.43 Å under the same conditions.
Simultaneously, Ru–Cl goes from 2.43 Å to 2.45–2.47 Å when a trans Sthp is replaced by
a Ste. This indicates that Ste are weaker π-acceptors than SDMSO and that Sthp is even
weaker than Ste.
The fac isomer III shows the longest Ru–Sthp bond (table 3). That would seem to indicate
a decrease in the tension on the coordinated macrocycle. Nevertheless, the ruthenium bond
angles permit to conclude that no such tension exists in any of the three forms. Isomer III
corresponds to the only one where all bond positions with π-acceptor characteristics are
trans to ligands which do not compete in such a way for electron density: DMSO is trans
to Sthp and Ste are trans to Cl. That has a direct impact on the bond lengths. On average,
the electron donors Cl and Sthp increase their metal bond lengths by 0.012 and 0.119 Å,
respectively, while electron acceptors Ste and DMSO show a decrease in 0.015 and 0.057
Å, respectively.
The electronic energy and scaled thermodynamic variables, as well as isomer abun-
dance, are indicated in table 4. At 298 K, isomer III shows G values at 4.6 and
4.9 kJ molÀ1 below I and II, respectively. Isomer composition in the gas phase at r.t. was
determined using a Boltzmann distribution of Gibbs free energy, with approximately 77%
of III, 12% of I, and 11% of II.
Structures I–III have the same crown thioether conformation with minimal internal devi-
ations (RMSD 6 0.09 Å; heavy atoms) and, at the same time, very different from the free
crown thioether-minimized structure (RMSD ≈ 3 Å), as can be seen in figure S4. The
energy required for ttbt rearrangement to the same positions of I–III corresponds to
the “pre-organization energy”. It was determined for single points of the three isomers at
the B3LYP/6-311+G(2d,p)/LANL08f level and measured 36.4, 36.5, and 32.5 kJ molÀ1
,
respectively. These data indicate that III is expected to be favored both kinetically and
thermodynamically, at least in the gas phase.
Since the solubility of the three isomers should not be too different, and the crystal
structure is dictated by forces acting at the molecular level, the fact that form II is
observed in the crystal phase indicates that such interactions are more relevant in II, alter-
ing the energy order compared with the one observed in the gas phase. This is plausible
since the lattice energy of a molecular crystal is significantly larger than the differences
observed in I–III [66]. Furthermore, atoms that induce polarity and are able to establish
hydrogen bonds have a larger contribution to the lattice energy than the carbon skeleton,
and it is expected that the location of DMSO and chloro atoms, which are positioned
differently relative to ttbt in the three isomers, will be the relevant variable [66].
The HOMO, HOMO-1, and HOMO-2 orbitals main composition include one “t2g type”
orbital from the metal ion (dxy, dxz, and dyz) and p orbitals of the chloro ligands. The
LUMO has contributions from dz2, a p orbital from sulfur of DMSO and a π orbital delo-
calized over thp. The LUMO+1 is mainly composed of dx2Ày2 from Ru(II) and p orbitals
Table 4. Energy, thermodynamic variables and composition of cis,fac-[RuCl2(DMSO)(ttbt)], 5, isomers for
minimized structures at the B3LYP/6-311+G(2d,p)/LANL08f level.
E
(Eh)
ΔE
H
(Eh)
ΔH
S
G298
(Eh)
ΔG
χi
(%)
(kJ molÀ1
)
(kJ molÀ1
)
(J molÀ1 KÀ1
)
(kJ molÀ1
)
I
À3550.251303
2.84
4.37
0.00
À3549.916286
À3549.915790
À3549.917253
2.59
3.84
0.00
708.616
711.883
715.573
À3549.996756
À3549.996631
À3549.998513
4.61
4.94
0.00
12.0
10.6
77.4
II À3550.250720
III À3550.252385

Ruthenium macrocycles
15
Figure 6. Contour plots at 0.05 au of HOMO-2 to LUMO+2 orbitals of the isomer [III] of 5: optimization at the
B3LYP/6-311+G(2d,p)/LANL08f level and representation with ChemCraft.
of chloro and Ste. HOMO-2 to LUMO+2 of III are represented in figure 6. The frontier
orbitals of I and II are very similar to the analogs of III but show some differences in
energy. The HOMO-LUMO gap decreases from I to III, presenting the following values
27,500, 26,800, and 26,600 cmÀ1, respectively.
2.6. Solubility and reactivity
Compounds 3, 4, and 6 are reasonably soluble in the majority of solvents because of their
ionic nature; neutral 2 and 5 are weakly soluble, except in DMSO or DMF, and water in
the case of 2.
The labilities of 1–3 were tested in polar coordinating solvents CH3CN, DMSO, and
water. The reflux of 1 in CH3CN does not result in any change of the coordination sphere,
even when NH4PF6 is added. This contrasts with aqueous solution results, under an excess
of chloride, where O-DMSO dissociation occurs [67].
fac-[RuCl2(DMSO)([9]aneS3)], 2, shows no reaction in CH3CN even under prolonged
1
reflux, while solubilization in DMSO-d6, followed by H NMR for 24 h, shows no signs
of exchange of chloro for DMSO-d6. Exchange of DMSO for DMSO-d6 is observed
instead, as previously reported for [RuCl2(DMSO)(tpy)] [68]. Nevertheless, adding an
equimolar amount of NH4PF6 to CH3CN resulted in formation of [RuCl(CH3CN)(DMSO)
([9]aneS3)]PF6, 7 (73% yield). Since Ru(II) prefers a dissociative substitution mechanism
[69] and PFÀ6 increases the reactivity of 2 in CH3CN, a five-coordinate intermediate is
plausible, stabilized by the non-coordinating PFÀ6 . A similar situation was recently
described by Izquierdo et al., where the reaction was followed by ESI-MS [33]. When 2 is
solubilized in water, followed by addition of NH4PF6, a solid compound precipitates that

16
J. Madureira and T.M. Santos
gives [Ru(CH3CN)3([9]anoS3)](PF6)2 (77%) after solubilization in CH3CN. This complex
has been previously described by Landgrafe and Sheldrick [28].
When cis-[RuCl(DMSO)([12]aneS4)]Cl, 3, is heated in CH3CN under reflux for 5 h, it
does not change its composition. If 3 is solubilized in CH3CN in the presence of NH4PF6,
the only modification that occurs is the counter-ion exchange from ClÀ to PF6À. But, when
the reaction is performed in CH3CN/water, with NH4PF6 in equimolar amount, the com-
plex cis-[RuCl(CH3CN)([12]aneS4)]PF6 is formed with an 89% yield [30]. In a similar
experiment, 3 was solubilized in water with a large excess of NaBr and heated for several
hours, followed by evaporation, solubilization in CH3CN, filtration (to remove salt) and
overnight reflux. Raman spectroscopy identified the isolated compound as cis-[RuCl
(CH3CN)([12]aneS4)]+, probably in the bromide form. Such results confirm that the Ru–Cl
bond of 3 is quite inert, with exchange typically taking place in the DMSO position [30].
So far, removing the chloro has been possible only with chelate ligands or good halogen
abstractors [30,70]. This supports the restricted ability of thioethers to neutralize positive
charges by σ donation [44,71].
Summarizing, these studies confirm that 2 and 3 have chloro ligands that are resistant to
coordinating solvents like CH3CN or DMSO. The presence of water significantly increases
the reactivity of 2, with all monodentate positions being able to be exchanged, while in 3
only DMSO labilization occurs. Detailed hydrolysis studies are underway for some of
these complexes and will be published separately.
3. Experimental
3.1. General data and physical measurements
All complexes were prepared under argon using Schlenk techniques. The solvents were
p.a. or superior quality. Ultra-pure water was used for aquation studies. Chemicals were
acquired from established international suppliers and used without purification.
Elemental analyzes (C, H, N, and S) were performed on a Leco CHNS-932 (Chemistry
Department, Aveiro University). The infrared spectra (4000–200 cmÀ1) were acquired on a
FTIR Mattson-7000 Galaxy series spectrometer (2 cmÀ1 resolution), with material dis-
persed in KBr (P400 cmÀ1) or CsI (P200 cmÀ1) pellets, while Raman spectra were
acquired on a Bruker RFS 100/S FT spectrometer, with Nd/YAG laser excitation
(1064 nm). NMR spectra in solution were registered on 300 or 500 MHz Bruker DRX
spectrometers. All chemical shifts refer to TMS or residual proton signals of the solvents.
The solid-state 13C-CP-MAS and 13C-HP Dec-MAS spectra were obtained on a Bruker
ARX spectrometer operating at 400 MHz (100.6 MHz for 13C) using glycine as internal
standard. The UV/Vis spectra were obtained on a Jasco V-560 spectrophotometer at 20°C.
ESI-MS spectra were acquired with a Micromass Q-TOF-2 (Micromass, Manchester) with
a Z-spray API source. The nominal mass resolution was set at 8000. 50 : 50 and 40 : 60
water/methanol mixtures were employed as eluents for 6 and 7, respectively. The capillary
needle voltage was 3 kV, and the cone voltage applied was in the range of 10–60 V.
3.2. Theoretical calculations
All calculations were performed on the bach.vcu.edu cluster at the Center for High Perfor-
mance Computing (VCU) using the Gaussian® 03 program [72], version D2. The “Bach”
cluster consists of a total of 764 AMD Opteron™ 64-bit cores, each with a minimum of

Ruthenium macrocycles
17
2 GB/core RAM, 14 TB internal disk storage, 1 TB total RAM, 2 TB of /home space, and /
tmp space of 50–164 GB per node. Networking infrastructure is gigabit Ethernet.
SCF convergence requested 10À8 on the root-mean-square density matrix, 10À6 on
maximum deviation on the density matrix and 10À6 on the energy. DFT optimization
requested fine grid accuracy (10À7 for energy and 10À6 for gradient).
Ttbt optimizations were performed for HF and B3LYP methods using the following
basis sets: 3-21G⁄, 6-31G(d), 6-31+G(d), 6-31+G(d,p), 6-31+G(2d,p), 6-311G(d), 6-311+G
(d), 6-311+G(d,p), 6-311+G(2d,p), and 6-311++G(2d,p). The results permitted to select
B3LYP/6-311+G(2d,p) as the more adequate model, which was subsequently used in the
coordination compound calculations.
Chem3D® Ultra v.8.0 program was used to build 5 isomers and their conformers, using
its ability to introduce lone pairs in sulfur with selected exo/endo orientation. MM2-mini-
mized structures can then lock local minima that were used as input for further calculations
at the B3LYP/6-31G(d)/LANL08f level that corresponds to an intermediate quality model,
the results of which were fed to the more accurate B3LYP/6-311+G(2d,p)/LANL08f.
LANL08f is the triple-ζ valence basis set and relativistic core potential of Roy et al. [63].
It is a recent revision of the classic Hay and Wadt LANL2DZ [73] and includes a new
contraction of the basis sets, which is more suited to DFT calculations than the previous
double ζ contractions, which were based upon Hartree–Fock atomic results. It is also
supplemented with a polarization f function that corresponds to the single primitive deter-
mined by Frenking and co-workers [64]. Despite the fact that its exponents have not origi-
nally been optimized for DFT, they are seldom used because of its good behavior [63].
The final model is able to deal with long-range interactions caused by stereochemical
hindrance and diffuse orbitals interaction for sulfur, chloro, and ruthenium (nephelauxetic
effect). For models with B3LYP/6-311+G(2d,p), or better quality, the scaling factors are
known to achieve convergence, even in more difficult cases (as polarized hydrogens
bonded to electronegative atoms) permitting a better thermodynamic data prediction
[74,75]. Scaling factors at 298 K for ΔHvib (1.0040) and S (1.0094) were taken from
Merrick et al. [75]. The mole fractions, Xi, for the three isomers were determined from the
difference in Gibbs free energy, ΔGi, using the Boltzmann distribution law, that is, Xi = exp
(ÀΔGi/RT)/[Σjexp(ÀΔGj/RT)], and the most stable isomer as energy reference.
Minimized structures correspond to local minima in the potential energy surface, since
no negative values were found on their vibrational determined frequencies.
Fractional to Cartesian coordinates conversion in the tetragonal crystal system of 5,
determined by E.L.S. Cheu, was carried out with the crystallographic tool of ChemCraft
[76]. For representation purposes, the hydrogens were inserted automatically in GaussView
[77] since they are absent in the solved crystal structure. Besides ChemCraft and Gauss
View, PyMol was also used as visualization/graphic program [78].
3.3. Syntheses
The complexes fac-[RuCl2(DMSO)3(DMSO)] (1), fac-[RuCl2(DMSO-d6)3(DMSO-d6)]
(1a), [RuCl2(DMSO)([9]aneS3)] (2), cis-[RuCl(DMSO)([12]aneS4)]Cl (3), cis-[RuCl
(DMSO)([14]aneS4)]PF6 (4), [Ru([9]aneS3)2](PF6)2, and [Ru(CH3CN)3([9]aneS3)](PF6)2
were prepared according to the literature [15,28,30,34,79].
The synthesis and characterization of the fully deuterated DMSO derivatives of 1, 2, and
3, as well as the bromo and iodo analogs of 2, are presented in Supplementary Material.

18
J. Madureira and T.M. Santos
fac-[RuCl2(DMSO)(ttbt)] (5) – One mmol of [RuCl2(DMSO)4] (485 mg) and one of
3,6,9,14-tetrathia-bicyclo[9.2.1]tetradeca-1(13),11-diene, ttbt (263 mg), were mixed in
absolute ethanol and heated at reflux for 4 h, with the mixture acquiring a brown color.
After cooling, the suspension was kept at À20 °C for 48 h. The solid was collected by fil-
tration under vacuum and washed with cold ethanol and diethyl ether. After 2 h drying at
70°C, it was suspended in 75 mL of water and extracted with chloroform until the extract
showed no color (200 mL). After concentration on the rotary evaporator (40 mL), the
remaining solvent was slowly evaporated in the fume hood. The solid was dried at 70°C
(yield: 130 mg; 25%). Anal. Calcd for C12H30Cl2ORuS5 · 0.2 DMSO · 0.25 CHCl3 (%):
C, 27.2; H, 3.9; S, 29.9. Found: C, 27.2; H, 3.8; S, 29.9. Another sample gave: Anal.
Calcd for C12H30Cl2ORuS5 · 0.4 DMSO · 0.4 CHCl3 (%): C, 26.8; H, 3.9; S, 29.3.
Found: C, 26.6; H, 3.9; S, 29.3.
1H NMR – δH (CDCl3), ppm: 7.11 (1H, d; thiophene), 7.06 (1H, d; thiophene) [4.50–
3.55] and [3.10–2.50] (12H, d + m, CH2 of ttbt); 3.50 (3H, s, CH3 of DMSO), 3.43 (3H, s,
CH3 of DMSO). FT-IR (KBr, cmÀ1): 3058 (νC–H aromatic), 3000 sh (νC–H DMSO), 2962
(νC–H CH2 of ttbt), 2916 (νC–H), 1873 + 1862, 1491 (νC=C thiophene), 1410 + 1384 sh
(δC–H), 1304 + 1292, 1251 + 1237, 1212, 1165, 1087 (νS=O), 1016 (ρC–H), 969, 926, 871,
821, 721 (νC–S), 681 (νC–S), 649, 573, 487 + 468 + 432 (νRu–S), 412 sh, 380 (δC–S–O), 293.
FT-Raman (cmÀ1): 3064, 3004, 2964, 2919, 2832, 1493, 1475 sh, 1416, 1332, 1235,
1172, 1104, 1019, 860, 804, 731, 716, 682, 647, 637, 575, 488 + 468 + 432 (νRu–S), 413
sh, 380, 360–300 several peaks, 293, 277 + 246 br (νRu–Cl), 206, 186, 135, 107 sh. UV/Vis
– (DMF) λmax, nm (ɛ Â 10À3 MÀ1 cmÀ1): 415 (1.7), 319 sh (4.7), 274 (15.1).
[RuCl(DMSO)([14]aneN4)]PF6 (6) – Two mmol of [RuCl2(DMSO)4] (969 mg) and two
mmol of [14]aneN4 (400 mg) were mixed in absolute ethanol and heated at reflux for 4 h.
The mixture darkens gradually until a final dark brown color is observed. After cooling, a
slight excess of NH4PF6 was added (4.2 mmol) with immediate precipitation. The mixture
was kept at À20°C for 48 h, after which it was filtered under vacuum and a dark brown
viscous material was obtained. Adding CH3CN allows the soluble brown fraction to be
separated from a yellow solid that was collected. The filtrate was evaporated until oil was
formed. A small amount of fresh CH3CN results in a new fraction of the yellow precipi-
tate. Both solid fractions were solubilized in acetone and filtered under vacuum to remove
an almost white solid. The filtrate was evaporated to dryness and dried at 65°C (yield:
481 mg; 43%).
1H NMR – δH (CD3NO2), ppm: 8.56, 8.37, 8.30 and 8.08 (NH, s), [3.65–3.40] (2H, m,
CH2), 3.32 (3H, s, DMSO), 3.27 (3H, s, DMSO), [3.25–3.0] (6H, m, CH2), [3.0–2.7] (6H,
m, CH2), [2.7–2.55] (2H, m, CH2), [2.3–1.7] (4H, m, CH2). FT-IR (cmÀ1, KBr): 3313,
3218, 3191 and 3153 (νN–H), 3096, 2974, 2959, 2924 + 2917, 2876 and 2859 (νC–H), 1456,
1423, 1400, 1365, 1301, 1281, 1246, 1228, 1206, 1186, 1127 and 1106 (δC–H), 1069
+ 1061 sh, 1043 + 1035, 1009, 957, 844 (PFÀ6 ), 740, 713, 558 (PF6À), 494, 478, {442 and
424 sh} (νRu–S), 395, 379 (δC–S–O), 304, 280 (νRu–Cl), 258. FT-Raman (cmÀ1): {3312,
3218, 3185 and 3159} (νN–H), 3027, 2993, 2977, 2965, 2942 + 2934, 2882 and 2860
(νC–H), 1481 (δN–H), 1458, 1445, 1381, 1281, 1250, 1137 and 1097 (δC–H), 1081 (νS=O),
1042, 1013 (δC–H), 1001, 958, 864, 847, 833, 801, 741 (PFÀ6 ), 717 and 684 (νC–S), 444
(νRu–S), 412, 397 (δC–S–O), 333, 315, 282 (νRu–Cl), 266, {253 and 239} (νRu–N), 215, 194,
182, 145. ESI-MS (H2O/MeOH 1 : 1): m/z = 415, [M]+ ≡ [RuCl(DMSO)([14]aneN4)]+;
377, [M-Cl]+; 299, [M-Cl-DMSO]+.

Ruthenium macrocycles
19
[RuCl(CH3CN)(DMSO)([9]aneS3)]PF6 (7) – One mmol of [RuCl2(DMSO)([9]aneS3)]
(430 mg) was added to 50 mL of CH3CN and heated at reflux for 2 h. 163 mg of NH4PF6
(1 mmol) was solubilized in 20 mL of CH3CN and added to the reaction. After 15 min, a
color change from orange to yellow was observed. Simultaneously, a white material settled
down, which was removed by filtration. The filtrate was concentrated to 10 mL and left
standing to evaporate slowly at room temperature. Orange crystals form after 24 h, while
yellow flocculates can be collected at higher concentration. The two fractions can easily be
separated in diethyl ether after sonication, since the denser, orange fraction settles down,
while the yellow fraction stays suspended. After collection the yellow fraction was washed
with diethyl ether and dried at 70°C, while the orange one was washed with diethyl ether,
solubilized in acetone, evaporated in a rotary evaporator and dried. Both fractions
correspond to the same compound (yield: 424 mg; 73%).
1H NMR – δH (acetone-d6), ppm: 3.36 (6H, s, DMSO), [3.25–2.75] (12H, m, CH2),
2.67 (3H, s, CH3CN). FT-IR (cmÀ1, KBr): 2997, 2958, 2938 and 2910 (νC–H), 2314 and
2287 (νC≡N), 1454, 1410, 1361, 1315, 1298, 1184, 1173 + 1167, 1118 (δC–H), 1101 + 1092
(νS=O), 1032, 977, 941, 921, 911, 842 (PFÀ6 ), 742, 720, 685, 662, 623, 558 (PFÀ6 ), {493,
460 and 430} (νRu–S), 377 (δC–S–O), 352, 340, 297, 256, 247 (νRu–Cl). FT-Raman (cmÀ1):
3012 sh, 2999, 2984, 2959 sh, 2939, 2918 and 2911 (νC–H), 2314 and 2286 (νC≡N), 1455,
1420 + 1412, 1363, 1316, 1298, 1185, 1173, 1138, 1128, 1119 (δC–H), 1100 + 1091 (νS=O),
1032, 1017, 1009, 994, 977, 947, 912, 741 (PFÀ6 ), 720, 684, 662, 620, 567, {496, 461 and
428} (νRu–S), 377 (δC–S–O), 353, 340, 311, 299, 284, 269, 248 (νRu–Cl), 224 (νRu–N), 211,
191, 173, 145, 127, 101. ESI-MS (H2O/MeOH 2 : 3): m/z = 435, [M]+ ≡ [RuCl(CH3CN)
(DMSO)([9]aneS3)]+; 412.9, [M – CH3CN + H2O]+; 394.9, [M À CH3CN]+.
4. Concluding remarks
Seven ruthenium(II)–chloro–dimethylsulfoxide complexes were prepared and characterized.
Previously known 1–4 were further characterized at the spectroscopic level and their reac-
tivity studied. Compounds 2 and 3 were studied in more detail by FT-IR, FT-Raman, and
UV/Vis. Deuterated forms of 1–3 and alternative halogen derivatives of 2 were prepared to
conduct a more rigorous assignment of vibrational and UV/Vis spectra. Reactivity and sol-
ubilization of such compounds in coordinating solvents (H2O, CH3CN, and DMSO) indi-
cate that the chosen macrocycle controls the species found in solution, with the chloro
positions of [RuCl2(DMSO)([9]aneS3)] (2) being more easily replaced than in cis-[RuCl
(DMSO)([12]aneS4)]Cl (3). The counter-ion has a direct impact on the reactivity, with
hexafluorophosphate helping solvolysis to occur and/or favoring precipitation of the chlo-
ride salt. In fact, [RuCl(CH3CN)(DMSO)([9]aneS3)]PF6 (7) could be isolated from a
CH3CN solution in such a way. A five-coordinate species is predicted to play a major role
on solvolysis processes, probably better stabilized by the bigger counter-ion.
Besides 7, two other new complexes of this class of compounds were presented.
[RuCl2(DMSO)(ttbt)] (5) is the first published octahedral complex of ttbt. It is coordinated
by three of its four sulfurs, in a fac arrangement (Ste–Ste–Sthp) according both to X-ray
crystal structure and theoretical calculations at the DFT level. NMR indicates that an
equilibrium of different isomers occurs in solution that agrees with DFT results, with
predicted abundances of 77% (I), 12% (II) and 11% (III) at r.t., based on a distribution of
Gibbs free energy at 298 K. They correspond to different positions of chloro and DMSO
in their internal relation with ttbt.

20
J. Madureira and T.M. Santos
[RuCl(DMSO)([14]aneN4)]PF6 (6) is a kinetically air stable Ru(II)–polyamine complex,
despite [14]aneN4 high σ-donor ability and lack of available orbitals for π back donation.
It shows a gradual (weeks) internal amine oxidation assisted by the ruthenium center.
Supplementary material
Synthesis and characterization of complexes 1a, 2a, 2b, 2c, and 3a are presented in
Supplementary Material. Infrared and Raman band assignments for 1, 2 and 3, same as
1
their deuterated DMSO analogs are presented in table S1, while H NMR spectra of 2 and
7 are shown in figures S1 and S2. Further details of the molecular modeling results and
methodology are also included in Supplementary Material, namely in figures S3 and S4.
The multi-Gaussian fitting of the convoluted electronic spectra of 2, 2b, and 2c are shown
in figures S5–S7.
Acknowledgements
Dr Paula Ferreira and Prof. Graça Santana-Marques (University of Aveiro) are thanked for
running solid-state 13C NMR and ESI-MS analysis, respectively. J.M. thanks FCT
(Portugal) for a post-doc grant (SFRH/BPD/41138/2007) and the Center for High
Performance Computing (VCU) for access to bach.vcu.edu cluster.
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