Efficient synthetic approaches to access ruthenium(II) complexes with 2-(Trimethylsilyl)ethyl- or acetyl-protected terpyridine-thiols

Article abstract of DOI:10.1002/ejic.201001249

A series of thiol-functionalized terpyridines (tpy) with protective groups, such as acetyl (Ac), 2-(trimethylsilyl)ethyl (TMSE), and tert-butyl (tBu), and the corresponding ruthenium(II) complexes were synthesized in high yields. The TMSE-protected thiol-

Full text of DOI:10.1002/ejic.201001249

FULL PAPER
DOI: 10.1002/ejic.201001249
Efficient Synthetic Approaches To Access Ruthenium(II) Complexes with
2-(Trimethylsilyl)ethyl- or Acetyl-Protected Terpyridine–Thiols
Hui-Min Wen,[a] Dao-Bin Zhang,[a] Li-Yi Zhang,[a] Lin-Xi Shi,[a] and Zhong-Ning Chen*[a]
Keywords: Electrochemistry / Ligand design / Ruthenium / Synthetic methods / Thiol / Tridentate ligands
A series of thiol-functionalized terpyridines (tpy) with protec- tained by a three-step synthetic procedure. By utilizing 4Ј-
tive groups, such as acetyl (Ac), 2-(trimethylsilyl)ethyl
(TMSE), and tert-butyl (tBu), and the corresponding rutheni-
um(II) complexes were synthesized in high yields. The
TMSE-protected thiol-functionalized RuII(tpy) complexes can
be readily converted into the corresponding ruthenium(II)
complexes with an acetyl group by using AgClO4/acetyl
chloride or TBAF/acetyl chloride. Based on this convenient
synthetic approach under mild conditions, the ruthenium(II)
complex [(AcSCH2C6H4tpy)(PPh3)2Ru(CϵCC6H4CϵCC6H5)-
](ClO4) {[12](ClO4)} with acetylthio–tpy was successfully ob-
{4-[(acetylsulfanyl)methyl]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyridine as a
chelating ligand, a dinuclear dicyanamido-linked ruthenium
complex was prepared, characterized, and immobilized onto
gold electrode surfaces to form self-assembled monolayers
(SAMs). The compounds were characterized by mass spec-
trometry, IR, 1H NMR and 13C NMR or 31P NMR spec-
troscopy, and elemental analysis. The solid-state structure of
complex [14](PF6)3 was determined by X-ray crystallography,
in which the intramolecular S⋅⋅⋅S distance was found to be
31.194(2) Å.
thiol ligands are unsuitable for the reactions under acidic
or basic conditions, especially for organometallic syntheses.
In many cases, 2-(trimethylsily)ethyl (TMSE)[7,9,15] is used
as a thiol-protecting group, because it exhibits much better
chemical stability than acetyl groups and is sufficiently
stable towards most of the reaction conditions employed.
Our synthetic strategy is to take advantage of the inertness
of the TMSE group under basic conditions. Nevertheless,
another problem arises from the difficulty in the synthesis
of TMSE-functionalized tpy compounds. To the best of our
knowledge, 2-(trimethylsilyl)ethyl sulfide (TMSCH2CH2SR,
R = alkyl, aryl) has been prepared by several methods,[8,9]
including: (i) the reaction of 2-(trimethylsilyl)ethane-
thiol with halogen-containing electrophilic reagents; (ii)
the reaction of 2-(trimethylsilyl)ethanethiol tosylate
(TMSCH2CH2STs) with a sulfenylate carbon atom; (iii) the
radical addition reaction of 2-(trimethylsilyl)ethanethiol
with olefins; (iv) the radical addition reaction of trimeth-
yl(vinyl)silane with thiol; and (v) the copper(I)-catalyzed re-
action of 2-(trimethylsilyl)ethanethiol with bithiophenyl io-
dide. By using these synthetic methods, thiol-functionalized
tpy compounds 2 and 3 with the TMSE protecting group
were synthesized in our laboratory. Another general pro-
cedure for Pd-catalyzed carbon–sulfur bond formation[10,12]
was utilized, in which compounds 3 and 5 were obtained
expediently by Pd-catalyzed reactions of 2-(trimethylsilyl)-
ethanethiol with triflate-substituted tpy compounds, which
are easily available reagents. We have also explored the syn-
thetic approach to access other types of thiol-protected tpy
compounds with tBu[11] or acetyl as the protecting group.
Furthermore, TMSE-protected RuII(tpy–thiol) complexes
Introduction
Self-assembled monolayers (SAMs) of thiols on metal
electrode surfaces or semiconductor surfaces[1] have con-
stantly been the focus of research interest over the last years
because of their potential application as molecular sen-
sors[2] or active substrates for molecular electronics.[3]
Among the compounds suitable for SAM preparation,
2,2Ј:6Ј,2ЈЈ-terpyridine (tpy) derivatives are quite attractive
candidates, because they are not only favorable electronic
conductors between the functional groups and the sub-
strates due to their favorable π conjugation, but also versa-
tile ligands suitable for formation of complexes with transi-
tion metal ions.[4,23] Particular interest focuses on 4Ј-substi-
tuted tpy ligands in which various substituents with dif-
ferent electronic or steric characteristics can be directly in-
troduced by the Kröhnke reaction or improved Kröhnke
reaction.[5] These tpy derivatives are likely further converted
into thiol-functionalized tpys, which can subsequently be
introduced onto gold surfaces to form SAMs. Accordingly,
it is of significance to develop convenient and feasible ap-
proaches to access thiol-functionalized tpy compounds.
Generally, thiol-containing tpy compounds are protected by
an acetyl moiety in the form of acetyl thioesters, which have
been extensively used.[6] Nevertheless, acetyl-protected tpy–
[a] State Key Laboratory of Structural Chemistry, Fujian Institute
of Research on the Structure of Matter, Chinese Academy of
Sciences,
Fujian 350002, China
E-mail: czn@fjirsm.ac.cn
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201001249.
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Ruthenium(II) Complexes with Protected Terpyridine–Thiols
can be readily converted into the corresponding acetyl-con-
taining ruthenium(II) complexes by using AgClO4/acetyl
chloride or TBAF/acetyl chloride as the reagents. Thus, a
series of thiol-functionalized tpy compounds and the corre-
sponding ruthenium complexes are accessible in excellent
yields. We describe herein the preparation and characteriza-
tion of mono- or dinuclear (acetylsulfanyl–tpy)rutheni-
um(II) complexes 12, 13, and 14, together with electrochem-
ical studies on the SAMs of 14 on gold electrode surfaces.
Results and Discussion
Scheme 2. Synthetic routes for compounds 3 and 4. (a) PCl5,
POCl3, reflux, 12 h; (b) NaSH, DMF, reflux, 4 h; (c) trimethyl-
(vinyl)silane, AIBN, toulene, 100 °C, 10 h; (d) DMAP, (AcO)2O,
CH2Cl2, r.t., 4 h.
Synthesis and Characterization
As shown in Scheme 1, AcS-containing compound 1 was
prepared by the reaction of 4Ј-[4-(bromomethyl)phenyl]-
2,2Ј:6Ј,2ЈЈ-terpyridine with potassium thioacetate in acetone
at 40 °C in 57% yield. Scheme 1 also depicts a general ap-
proach to 4Ј-[4-({[2-(trimethylsilyl)ethyl]sulfanyl}methyl)-
phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine (2), in which a classical
AIBN-initiated free-radical reaction of 4Ј-[4-(mercap-
tomethyl)phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine with unsaturated
trimethyl(vinyl)silane in CCl4 was performed in 63% yield.
To obtain compound 3 (Scheme 2), 4Ј-chloro-2,2Ј:6Ј,2ЈЈ-
terpyridine was first prepared by the reaction of 2,6-bis(2Ј-
pyridyl)-4-pyridone with PCl5 in boiling POCl3, followed by
a classical reaction of 4Ј-chloro-2,2Ј:6Ј,2ЈЈ-terpyridine with
sodium hydrogen sulfide in DMF, resulting in the isolation
of 2,2Ј:6Ј,2ЈЈ-terpyridine-4Ј-thiol as a yellow solid. Unlike
the preparation of 2, the reaction of 2,2Ј:6Ј,2ЈЈ-terpyridine-
4Ј-thiol with trimethyl(vinyl)silane in CCl4 did not give pure
3 although it was accessible in low yield (36%) by using
toluene as the solvent. Nevertheless, compound 3 could be
prepared in high yield (96%) by the coupling reaction of
4Ј-[(trifluoromethyl)sulfono]-2,2Ј:6Ј,2ЈЈ-terpyridine with 2-
(trimethylsilyl)ethanethiol, catalyzed by Pd2(dba)3–
Xantphos[10] as shown in Scheme 3. Using the same syn-
thetic procedure, we then explored the protocol of the palla-
dium-catalyzed system to synthesize other thiol-protected
tpy compounds in high yields (Table 1).
Scheme 3. Palladium-catalyzed synthesis of TMSE-protected com-
pound 3.
Table 1. Palladium-catalyzed cross-coupling reactions of tpy tri-
flates with thiol reagents.
R
RЈ
Product
Yield [%][a]
Tfo
Tfo
TfoC6H4
TfoC6H4
Tfo
TMSES
AcS
TMSESC6H4
tBuSC6H4
tBuS
3
4
5
6
7
96
46, 30[b]
89
88
95
[a] Pure products isolated by column chromatography. [b] The reac-
tion was performed by using 2.5 mol-% Pd2(dba)3, 5 mol-%
Xantphos, 1.5 equiv. of potassium thioacetate, 2.0 equiv. of Hünig’s
Although AcS-containing tpy 4 was obtained in a lower
yield (46%) relative to compound 3 (96%, Scheme 3), the
Pd-catalyzed cross-coupling method can improve the syn- base and 4 mL of 1,4-dioxane under microwave conditions.[13]
Scheme 1. Synthetic routes for compounds 1 and 2. (a) NH2CSNH2, EtOH, NaOH, HCl; (b) potassium thioacetate, acetone, 40 °C, 4 h;
(c) trimethyl(vinyl)silane, AIBN, CCl4, reflux, 10 h.
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thetic procedure and reduce the cost compared with the this synthetic procedure. Instead, TBAF/acetyl chloride is
classical addition reaction (4 in 40% yield, Scheme 2). favorable for the transformation. With the desilylation of
Compound 4 could also be obtained by the reaction of 4Ј- [(TMSESC6H4tpy)(PPh3)2RuCl](ClO4) or [(TMSEStpy)-
[(trifluoromethyl)sulfono]-2,2Ј:6Ј,2ЈЈ-terpyridine with po- (PPh3)2RuCl](ClO4) initiated by TBAF in THF solution,
tassium thioacetate under microwave conditions according acetylation could be readily performed by the addition of
to the method described by Lai et al.[12] in 30% yield. As acetyl chloride, giving rise to the formation of [(AcSC6H4-
presented in Table 1, other thiol-functionalized tpy com- tpy)(PPh3)2RuCl](ClO4) {[9](ClO4)} in 80% yield or
pounds (5–7) with TMSE or tBu as the protecting group [(AcStpy)(PPh3)2RuCl](ClO4) {[10](ClO4)} in 41% yield.
could also be prepared by Pd-catalyzed reactions according
to the described procedures in high yields (5, 89%; 6, 88%;
7, 95%).
Since acetyl-protected tpy–thiol–metal complexes are
more favorable for the preparation of SAMs,[15b] it is neces-
sary to transform the TMSE-protected tpy–thiol–metal
complexes into the corresponding acetyl-protected species
under mild conditions.[14,15] As indicated in Scheme 4,
TMSE-protected thiol-functionalized RuII(tpy) complexes
can be readily converted into the corresponding rutheni-
um(II) complexes with acetyl group by using AgClO4/acetyl
chloride or TBAF/acetyl chloride as the reagents. Thus,
[(AcSCH2C6H4tpy)(PPh)RuCl](ClO4) {[8](ClO4)} was ob-
Scheme 4. Procedure for the transformation of TMSE-protected
ruthenium(II) complexes into the acetyl-protected species.
tained by the reaction of [(TMSESCH2C6H4tpy)(PPh3)2-
RuCl](ClO4) with AgClO4/acetyl chloride in dry CH3CN,
in which AgClO4 serves as a promoter to accelerate this
In view of the convenient conversion to metal complexes
conversion, in 86% yield. The acetyl-protected tpy–thiol with acetyl-protected tpy–thiol from the corresponding
compounds 9 and 10, however, could not be accessed by TMSE-protected tpy–thiol species under mild conditions,
Scheme 5. Synthetic routes for ruthenium(II) complexes 11 and 12. (a) AgClO4, acetone, reflux; (b) 1-ethynyl-4-(phenylethynyl)benzene,
TEA, CH3OH, reflux; (c) AgClO4, acetyl chloride, CH3CN, r.t.
Scheme 6. Synthetic routes for ruthenium(II) complexes 13 and 14. (a) sodium dicyanamide, methanol, reflux; (b) 8, AgClO4, acetone,
r.t., no light.
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Ruthenium(II) Complexes with Protected Terpyridine–Thiols
(acetylthio–tpy)ruthenium(II) complex [12](ClO4) was suc- Table 2. Selected bond lengths [Å] and angels [°] for [14].
cessfully prepared by a three-step synthetic procedure as de-
Ru–N1
Ru–P1
Ru–P2
Ru–N3
2.060(3)
2.408(1)
2.411(1)
2.097(5)
Ru–N4
Ru–N5
N1–C1
C1–N2
1.960(3)
2.096(4)
1.132(6)
1.372(20)
picted in Scheme 5. As TMSE-protected (tpy–thiol)rutheni-
um(II) complexes are sufficiently stable during ligand trans-
formation, the reaction of [(TMSESCH2C6H4tpy)(PPh3)2-
RuCl](ClO4) with AgClO4 firstly gave the acetone-coordi-
nated complex [(TMSESCH2C6H4tpy)(PPh3)2Ru(acetone)]-
(ClO4) by removal of the coordinated chloride (precipitated
as AgCl), which reacted with HCϵCC6H4CϵCC6H5 in the
presence of NEt3, to afford [11](ClO4) in 60% yield. The
target complex [12](ClO4) with the acetyl-protected tpy–
thiol was thus accessible by the reaction of [11](ClO4) with
AgClO4 and acetyl chloride in 80% yield.
N3–Ru–P1
N3–Ru–P2
N4–Ru–P1
N4–Ru–P2
N5–Ru–P1
N5–Ru–P2
P1–Ru–P2
C15–N3–Ru
N1–Ru–P1
N1–Ru–P2
91.29(11)
86.43(11)
91.43(10)
90.69(10)
89.31(11)
93.77(11)
176.56(5)
129.05(38)
86.54(10)
91.28(10)
C1–N1–Ru
N1–C1–N2
N1–Ru–N3
N1–Ru–N4
N1–Ru–N5
N3–Ru–N4
N3–Ru–N5
N4–Ru–N5
C11–N3–Ru
S1–C32–C29
166.35(59)
155.75(78)
99.44(21)
177.52(23)
102.4(2)
79.18(19)
158.14(14)
78.96(19)
129.05(38)
113.11(64)
As shown in Scheme 6, by utilizing 4Ј-{4-[(acetylsulfan-
yl)methyl]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyridine
(AcSCH2C6H4-
tpy) as a chelating ligand, the mononuclear complex
[(AcSCH2C6H4tpy)(PPh3)2Ru{N(CN)2}](ClO4) {[13](ClO4)}
with terminally coordinated dicyanamide was prepared by
equatorial planes of Ru and RuA octahedrons form a dihe-
dral angle of 21.03(10)°, which is smaller than those found
in dinuclear ruthenium complexes [{(Phtpy)(PPh3)2Ru}2-
(CϵCCϵC)], [{(bph)(PPh3)2Ru}2(CϵCCϵC–CϵCCϵC)],
and [{(bph)(PPh3)2Ru}2{CϵC(C6H4)2CϵC}].[24] The C1–
the reaction of
8 with excess sodium dicyanamide
[NaN(CN)2]. The reaction of 13 with a further equivalent
of 8 afforded dicyanamido-linked dinuclear ruthenium(II)
–
N2–C1A angle [121.7(8)°] of the bridging N(CN)2 is com-
complex
[{(AcSCH2C6H4tpy)(PPh3)2Ru}2{μ-N(CN)2}]-
parable to those in [{Cp(dppe)Fe}2{N(CN)2}]+ [123.3(13)°]
and [{Cp(PPh3)Ru}2{N(CN)2}]+[23b] [127.2(9)°], where
(ClO4)3 {[14](ClO4)3}.
–
N(CN)2 adopts a “V” conformation due to sp2 hybridiza-
Crystal Structure
tion of the central N atom. The N1–C1–N2 and Ru–N1–
C1 angels are 155.75(78) and 166.35(59)°, respectively, re-
vealing that the N–CϵN–Ru linkage deviates largely from
linearity. The Ru···RuA distance through bridging dicyan-
amide is 8.677(8) Å. The intramolecular S···S distance is
31.194(2) Å at the two termini of the molecule.
Crystals of [14](PF6)3·H2O·2C6H14 {prepared by meta-
thesis of perchlorate in [14](ClO4)3 with potassium
hexafluorophosphate} were grown by layering hexane onto
the dichloromethane solution. The crystal structure consists
of one [{(AcSCH2C6H4tpy)(PPh3)2Ru}2{μ-N(CN)2}]3+ cat-
ion, three hexafluorophosphate anions, and one water and
two hexane molecules of solvation, which have been treated
as a diffuse contribution to the overall scattering without
specific and fixed atom positions by SQUEEZE/PLATON.
Electrochemical Properties
The electrochemical properties of 14 were investigated by
A
perspective
[{(AcSCH2C6H4tpy)(PPh3)2Ru}2{μ-N(CN)2}]3+ is depicted averaging the cathodic and anodic peak potentials E1/2
in Figure 1. Selected bond lengths and angles are listed in (Epc + Epa)/2. The separation of the peak potentials ΔEp
Table 2. was calculated by ΔEp = Epa – Epc. As shown in Figure S1,
view
of
the
complex
cation cyclic voltammetry. Redox potentials E1/2 were obtained by
=
The complex cation consists of two {(AcSCH2C6H4- the cyclic voltammogram of the dinuclear ruthenium com-
–
tpy)(PPh3)2Ru} units linked by a dicyanamide [N(CN)2 ] plex 14 in 0.1 m TBAPF6/CH2Cl2 solution displays two re-
through an Ru–N linkage. The RuII centers are six-coordi- versible waves at 1.10 and 1.48 V vs. Ag/AgCl, due to the
nate to form an elongated octahedron composed of N4P2 stepwise one-electron processes RuII,II2/RuIII,II
and
2
donors in which the equatorial plane is built by four N do- RuIII,II2/RuIII,III2, respectively. The potential separation
nors from tpy and dicyanamide [Ru–N3 2.097(5) Å and (ΔE1/2 = 0.38 V) of the two stepwise redox waves and the
Ru–N1 2.060(3) Å], and the axial sites are occupied by two comproportionation constant Kc (2.65ϫ106) for the forma-
trans-oriented P donors of PPh3 [Ru–P 2.408(1) Å]. The tion of RuIII,II species suggest that a quite large Ru···Ru
2
Figure 1. ORTEP diagram of 14 with 30% thermal ellipsoid. Phenyl rings on phosphorus atoms are omitted for clarity.
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electronic interaction is most likely operative across the thetic and conversion methods, ruthenium(II) complexes
bridging dicyanamide. Interestingly, ΔE1/2 and Kc are much with 2-(trimethylsilyl)ethyl- or acetyl-protected tpy–thiols
larger than those in our previously described N(CN)2- are accessible, which affords an opportunity to experimen-
bridged complexes [{Cp(dppe)Fe}2{N(CN)2}]+ (ΔE1/2
=
tally probe the conductive characteristics of molecular wires
0.141 V and Kc = 240) and [{Cp(PPh3)Ru}2-{N(CN)2}]+ based on Ru(tpy) compounds. Further studies on the sur-
(ΔE1/2 = 0.178 V and Kc = 1020),[23b] implying a significant face and interface characterization on gold electrodes are
influence from the ancillary chelating tpy ligand.
underway in our laboratory.
When a gold electrode is immersed into a CH2Cl2 solu-
tion of complex 14, SAMs are formed onto the gold sur-
face. A preliminary electrochemical study of the self-as-
sembled monolayers (SAMs) based on 14 on a gold elec-
trode was performed, and the CVs are shown in Figure 2.
Two reversible redox waves were observed at 1.16 and
1.54 V with ΔE1/2 = 0.38 V, comparable with those in solu-
tion except for a little anodic shift of the redox waves in the
SAMs. A linear correlation of current intensities of the an-
odic and cathodic peaks with the scan rates indicates that
complex 14 was indeed assembled on the gold surface.
Furthermore, the redox reversibility is distinctly improved
once complex 14 (Figure 2) is immobilized on to the gold
surface to form SAMs compared with that in solution (Fig-
ure S1). The surface coverage of complex 14 estimated from
the electric charge of the anodic peak around 1.16 V (Fig-
ure 2) is 4ϫ10–11 molcm–2. This value is more than twice
the experimental value (1.5ϫ10–11 molcm–2) of the SAMs
from a 1,3-butadiyne-linked diruthenium complex onto a
gold surface in a lying flat mode.[24c] Based on the surface
coverage and the rigid and bulky groups of four tri-
phenylphosphane and two phenylterpyridyl ligands, it is
likely that complex 14 adsorbs onto the gold surface with
only one terminal thiol group.
Experimental Section
General: Manipulations were carried out under dry argon by using
standard Schlenk techniques and vacuum-line systems. Solvents
were dried by standard methods and distilled prior to use. The
reagents Pd2(dba)3, Xantphos, silver perchlorate, tetra-n-butylam-
monium hexafluorophosphate (TBAPF6), tetra-n-butylammonium
fluoride (TBAF), potassium thioacetate, trimethyl(vinyl)silane
(H2C=CHSiMe3),
2-(trimethylsilyl)ethanethiol
(HSCH2CH2-
SiMe3), 2-methyl-2-propanethiol, and sodium dicyanamide
[NaN(CN)2] were purchased from commercial sources (Alfa Aesar,
Acros and Aldrich Chemical Co.). 4Ј-[4-(Bromomethyl)phenyl]-
2,2Ј:6Ј,2ЈЈ-terpyridine (BrCH2C6H4tpy),[16,17] 4Ј-[4-(mercapto-
methyl)phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine (HSCH2C6H4tpy),[17] 2,6-
bis(2Ј-pyridyl)-4-pyridone,[18]
4Ј-chloro-2,2Ј:6Ј,2ЈЈ-terpyridine
(Cltpy),[18a] 2,2Ј:6Ј,2ЈЈ-terpyridine-4Ј-thiol (HS-tpy),[19] 4Ј-[(trifluo-
romethyl)sulfono]-2,2Ј:6Ј,2ЈЈ-terpyridine (Tfotpy),[20] 4Ј-{[4-(tri-
fluoromethyl)sulfono]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyridine
(TfoC6H4-
tpy),[21] and 1-ethynyl-4-(phenylethynyl)benzene (HCϵCC6H4Cϵ
CC6H5)[22] were prepared according to literature procedures.
[(TMSESCH2C6H4tpy)(PPh3)2RuCl](ClO4), [(TMSESC6H4tpy)-
(PPh3)2RuCl](ClO4),
[(TMSEStpy)(PPh3)2RuCl](ClO4),
and
[(AcSCH2C6H4tpy)(PPh3)2RuCl](ClO4) were synthesized by modi-
fication of described procedures.[23,24] Caution! Perchlorate salts are
potentially explosive and should be handled carefully.
General Procedure for Palladium-Catalyzed Aryl–Sulfur Bond For-
mation: The compounds with C–S bond formation were synthe-
sized according to the method described by Itoh et al.;[10] tpy tri-
flates, Pd2(dba)3, and Xantphos were placed in a 100 mL two-neck
flask. The flask was charged with dry dioxane, iPr2NEt, and thiol
under argon. The mixture was stirred at reflux for 14 h. The sol-
vents were removed, and the residue was used for column
chromatography separation on silica gel to afford the correspond-
ing thiol-protected tpy compound.
General Procedure To Convert 2-(Trimethylsilyl)ethyl (TMSE) Pro-
tected Thiol into Acetyl-Protected Thioesters.[8d,14,15] Method I: A
mixture of silver perchlorate (5 equiv.) and excess acetyl chloride
(10 equiv.) was stirred vigorously in dry CH3CN at room tempera-
ture in the dark. When AgCl had precipitated completely, the
TMSE-protected thioether was added and the solution stirred for
a further 30 min. A saturated aqueous solution of NaHCO3 was
added to the filtrate and extracted with CH2Cl2. The combined
organic layers were dried in Na2SO4, and the solvent was removed
in vacuo. The residue was used for column chromatography separa-
tion on silica gel, giving the anticipated acetylsulfanyl-containing
compound. Method II: A THF solution of TBAF (10 equiv., 1.0 m)
was added to a solution of the TMSE-protected compound in dry
THF. The reaction mixture was stirred at room temperature for
1 h, followed by treatment with acetyl chloride (20 equiv.). The
solution was then diluted with CH2Cl2 and a saturated aqueous
solution of NaHCO3, and then washed with water three times. The
collected organic layers were dried with Na2SO4, and the solvent
was removed in vacuo. The acetylsulfanyl-functionalized product
Figure 2. Cyclic voltammogram of SAMs of 14 on a gold electrode
(as working electrode) recorded in a 0.1 m TBAPF6/CH2Cl2 solu-
tion. The scan rates are 50, 100, 200, 300, 400, 500 mVs–1. Inset:
Linear relationship between the anodic or cathodic peak current
(E1/2 = 1.16 V) and the scan rates.
Conclusion
Feasible synthetic approaches to a series of thiol-func-
tionalized tpy compounds and the corresponding ruthe-
nium complexes have been established in which the thiol
was protected by acetyl, TMSE, or tBu. Through the syn- was purified by chromatography on a silica gel column.
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Ruthenium(II) Complexes with Protected Terpyridine–Thiols
4Ј-{4-[(Acetylsulfanyl)methyl]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyridine
4Ј-[4-(Bromomethyl)phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine
(1):
(1.00 g,
aryl–sulfur
bond
formation,
4Ј-[(trifluoromethyl)sulfono]-
2,2Ј:6Ј,2ЈЈ-terpyridine (0.30 g, 0.79 mmol), potassium thioacetate
(0.14 g, 1.18 mmol), Pd2(dba)3 (0.018 g, 0.02 mmol), Xantphos
(0.023 g, 0.04 mmol), iPr2NEt (0.26 mL, 1.58 mmol), and dioxane
(40 mL) were used to yield the product (0.11 g, 46%) as an off-
2.50 mmol) and potassium thioacetate (0.425 g, 3.75 mmol) were
stirred in acetone (50 mL) at 40 °C for 4 h. After the solution had
cooled to room temperature, the solvent was removed under re-
duced pressure. The crude product was extracted with ethyl acetate,
and the organic layer was dried with MgSO4. The filtrate was con-
centrated and chromatographed on a silica gel column by using n-
hexane/CH2Cl/ethyl acetate (8:3:2) as eluent to give a colorless so-
white solid. M.p. 166–168 °C. IR (KBr): ν = 1716 (s, C=O) cm–1.
˜
ESI-MS: m/z (%) = 308 (100) [M + 1]+. 1H NMR (CDCl3): δ =
2.50 (s, 3 H), 7.35 (m, 2 H), 7.86 (t, J = 7.7 Hz, 2 H), 8.53 (s, 2 H),
8.61 (d, J = 8.0 Hz, 2 H), 8.70 (d, J = 4.5 Hz, 2 H) ppm. 13C NMR
(CDCl3): δ = 30.7, 121.4, 124.1, 125.3, 136.9, 140.7, 149.2, 155.5,
lid. Yield 0.563 g (57%). M.p. 169 °C. IR (KBr): ν = 1679 (s, C=O)
˜
1
cm–1. ESI-MS: m/z (%) = 398 (100) [M + 1]+. H NMR (CDCl3): 156.0, 191.6 ppm. C17H13N3OS (307.37): calcd. C 66.43, H 4.26, N
δ = 2.38 (s, 3 H), 4.19 (s, 2 H), 7.36 (dd, J = 7.4, J = 4.8 Hz, 2 H),
7.43 (d, J = 8.3 Hz, 2 H), 7.87 (m, 4 H), 8.67 (d, J = 8.0 Hz, 2 H),
8.73 (m, 4 H) ppm. 13C NMR (CDCl3): δ = 30.4, 33.2, 118.8, 121.4,
123.9, 127.6, 129.4, 136.9, 137.5, 138.7, 149.1, 149.8, 155.9, 156.2,
195.0 ppm. C24H19N3OS (397.49): C 72.52, H 4.82, N 10.57; found
C 72.16, H 4.72, N 10.49.
13.67; found C 66.09, H 4.25, N 13.38.
4Ј-(4-{[2-(Trimethylsilyl)ethyl]thio}phenyl)-2,2Ј:6Ј,2ЈЈ-terpyridine
(5): According to the general procedure for Pd-catalyzed aryl–sul-
fur bond formation, 4Ј-{4-[(trifluoromethyl)sulfono]phenyl}-
2,2Ј:6Ј,2ЈЈ-terpyridine (0.914 g, 2.00 mmol), 2-(trimethylsilyl)eth-
anethiol (0.32 mL, 2.00 mmol), Pd2(dba)3 (0.046 g, 0.05 mmol),
Xantphos (0.058 g, 0.1 mmol), iPr2NEt (0.66 mL, 4.00 mmol) and
dioxane (40 mL) were used to yield the product (0.79 g, 89%) as a
4Ј-[4-({[2-(Trimethylsilyl)ethyl]sulfanyl}methyl)phenyl]-2,2Ј:6Ј,2ЈЈ-ter-
pyridine (2): 4Ј-[4-(Mercaptomethyl)phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine
(500 mg, 1.41 mmol), trimethyl(vinyl)silane (170 mg, 1.70 mmol),
and azoisobutyronitrile (AIBN) (5.78 mg, 0.04 mmol) were added
to dry CCl4 (50 mL), and the mixture was heated at 90 °C for 5 h.
The solvent was removed in vacuo, and the residue was purified by
column chromatography on silica gel by using n-hexane/CH2Cl2/
ethyl acetate (8:3:2) as eluent to give a colorless oil. Yield 404 mg
yellowish solid. M.p. 137–139 °C. IR (KBr): ν = 1247 (m, Si–C)
˜
cm–1. ESI-MS: m/z (%) = 442 (100) [M + 1]+. H NMR (CDCl3):
1
δ = 0.08 (s, 9 H), 0.99 (t, J = 9.0 Hz, 2 H), 3.05 (t, J = 9.0 Hz, 2
H), 7.37 (m, 2 H), 7.41 (d, J = 8.2 Hz, 2 H), 7.90 (m, 4 H), 8.68
(d, J = 8.0 Hz, 2 H), 8.74 (s, 4 H) ppm. 13C NMR (CDCl3): δ =
–1.7, 16.8, 29.1, 118.5, 121.4, 123.9, 127.6, 128.6, 135.5, 136.9,
138.9, 149.1, 149.6, 155.9, 156.2 ppm. C26H27N3SSi (441.66): calcd.
C 70.71, H 6.16, N 9.51; found C 70.70, H 6.20, N 9.50.
(63%). IR (KBr): ν = 1247 (m, Si–C) cm–1. ESI-MS: m/z (%) =
˜
1
456 (100) [M + 1]+. H NMR (CDCl3): δ = 0.00 (s, 9 H), 0.89 (m,
2 H), 2.50 (m, 2 H), 3.79 (s, 2 H), 7.34 (dd, J = 7.6, J = 4.8 Hz, 2
H), 7.44 (d, J = 8.2 Hz, 2 H), 7.86 (m, 4 H), 8.66 (d, J = 8.0 Hz, 2
H), 8.72 (m, 4 H) ppm. 13C NMR (CDCl3): δ = –1.7, 17.0, 27.0,
35.8, 118.7, 121.4, 123.8, 127.4, 129.4, 136.9, 137.0, 139.8, 149.1,
149.9, 155.9, 156.3 ppm. C27H29N3SSi (455.69): calcd. C 71.16, H
6.41, N 9.22; found C 71.13, H 6.59, N 9.13.
4Ј-[4-(tert-Butylsulfanyl)phenyl]-2,2Ј:6Ј,2ЈЈ-terpyridine (6): Accord-
ing to the general procedure for Pd-catalyzed aryl–sulfur bond for-
mation, 4Ј-{4-[(trifluoromethyl)sulfono]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyri-
dine (0.457 g, 1 mmol), 2-methyl-2-propanethiol (0.13 mL,
1.1 mmol), Pd2(dba)3 (0.023 g, 0.03 mmol), Xantphos (0.029 g,
0.05 mmol), iPr2NEt (0.33 mL, 2 mmol), and dioxane (40 mL) were
used to yield the product (0.397 g, 88%) as a white solid. M.p. 168–
170 °C. ESI-MS: m/z (%) = 420 (100) [M + Na]+. 1H NMR
(CDCl3): δ = 1.34 (s, 9 H), 7.38 (dd, J = 6.6, J = 4.9 Hz, 2 H), 7.58
(m, 2 H), 7.90 (m, 4 H), 8.70 (d, J = 8.0 Hz, 2 H), 8.75 (m, 4 H)
ppm. 13C NMR (CDCl3): δ = 31.0, 46.4, 118.9, 121.3, 123.9, 127.4,
133.9, 136.9, 137.8, 138.9, 149.1, 149.6, 156.0, 156.1 ppm.
C25H23N3S (397.54): calcd. C 75.53, H 5.83, N 10.57; found C
75.66, H 5.83, N 10.56.
4Ј-{[2-(Trimethylsilyl)ethyl]sulfanyl}-2,2Ј:6Ј,2ЈЈ-terpyridine
(3).
Method I: Compound 3 (0.249 g, 0.68 mmol) was obtained from
2,2Ј:6Ј,2ЈЈ-terpyridine-4Ј-thiol (0.50 g, 1.87 mmol) according to the
synthetic procedure of compound 2 except for using toluene instead
of CCl4 as solvent. Yield 0.25 g (36%). Method II. According to
the general procedure for Pd-catalyzed aryl–sulfur bond formation,
4Ј-[(trifluoromethyl)sulfono]-2,2Ј:6Ј,2ЈЈ-terpyridine
(0.38 g,
1 mmol), 2-(trimethylsilyl)ethanethiol (0.16 mL, 1 mmol), Pd2-
(dba)3 (0.023 g, 0.03 mmol), Xantphos (0.029 g, 0.05 mmol),
iPr2NEt (0.33 mL, 2 mmol), and dioxane (20 mL) were used to
4Ј-(tert-Butylsulfanyl)-2,2Ј:6Ј,2ЈЈ-terpyridine (7): According to the
general procedure for Pd-catalyzed aryl–sulfur bond formation,
4Ј-{4-[(trifluoromethyl)sulfono]phenyl}-2,2Ј:6Ј,2ЈЈ-terpyridine
(0.381 g, 1 mmol), 2-methyl-2-propanethiol (0.13 mL, 1.1 mmol),
Pd2(dba)3 (0.023 g, 0.03 mmol), Xantphos (0.029 g, 0.05 mmol),
iPr2NEt (0.33 mL, 2 mmol), and dioxane (20 mL) were used to
yield the product (0.305 g, 95%) as a white solid. M.p. 120–122 °C.
yield the product (0.35 g, 96%) as a colorless oil. IR (KBr): ν =
˜
1
1247 (m, Si–C) cm–1. ESI-MS: m/z (%) = 366 (100) [M + 1]+. H
NMR (CDCl3): δ = 0.12 (s, 9 H), 1.06 (m, 2 H), 3.20 (m, 2 H),
7.33 (dd, J = 7.4, J = 4.8 Hz, 2 H), 7.85 (t, J = 7.7 Hz, 2 H), 8.31
(s, 2 H), 8.60 (d, J = 8.0 Hz, 2 H), 8.69 (m, 2 H) ppm. 13C NMR
(CDCl3): δ = –1.7, 16.3, 26.8, 117.7, 121.4, 123.9, 136.8, 149.1,
152.0, 154.9 ppm. C20H23N3SSi (365.57): calcd. C 65.71, H 6.34, N
11.49; found C 65.59, H 6.38, N 11.32.
1
ESI-MS: m/z (%) = 344 (100) [M + Na]+. H NMR (CDCl3): δ =
1.47 (s, 9 H), 7.33 (dd, J = 7.5, J = 4.8 Hz, 2 H), 7.85 (t, J = 7.7 Hz,
2 H), 8.58 (s, 2 H), 8.61 (d, J = 8.0 Hz, 2 H), 8.71 (m, 2 H) ppm.
13C NMR (CDCl3): δ = 31.5, 47.1, 121.3, 123.9, 126.5, 136.8, 146.8,
149.2, 155.3, 155.9 ppm. C19H19N3S (321.44): calcd. C 70.99, H
5.96, N 13.07; found C 71.21, H 6.07, N 12.94.
4Ј-(Acetylsulfanyl)-2,2Ј:6Ј,2ЈЈ-terpyridine (4). Method I: A mixture
of 2,2Ј:6Ј,2ЈЈ-terpyridine-4Ј-thiol (0.10 g, 0.38 mmol), acetic anhy-
dride (0.07 mL, 0.75 mmol), and 4-(dimethylamino)pyridine
(DMAP) (0.018 g, 0.15 mmol) was stirred in CH2Cl2 (10 mL) at
room temperature for 4 h. The solution was diluted with CH2Cl2
and a saturated aqueous solution of NaHCO3, and then washed
with water three times. The collected organic layers were dried with
Na2SO4, and the solvent was removed in vacuo. The product was
purified by column chromatography on silica gel by using hexane/
[(AcSCH2C6H4tpy)(PPh3)2RuCl](ClO4) {[8](ClO4)}: This com-
pound was obtained by desilylation of [(TMSESCH2C6H4tpy)-
(PPh3)2RuCl](ClO4) (100 mg, 0.08 mmol) according to Method I of
the general conversion using excess acetyl chloride (10 equiv.) and
AgClO . Yield 0.08 g (86%). IR (KBr): ν = 1689 (m, C=O), 1089
˜
4
(s, ClO4), 698 (s, P–C) cm–1. ESI-MS: m/z (%) = 1057 (100) [M –
CH2Cl2/ethyl acetate (8:3:2) as eluent. Yield 0.046 g (40%). ClO4]+. H NMR (CD3CN): δ = 2.39 (s, 3 H), 4.25 (s, 2 H), 7.07–
1
Method II: According to the general procedure for Pd-catalyzed
7.27 (m, 32 H), 7.57 (m, 4 H), 7.69 (m, 4 H), 7.84 (d, J = 7.6 Hz,
1789
Eur. J. Inorg. Chem. 2011, 1784–1791
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org

H.-M. Wen, D.-B. Zhang, L.-Y. Zhang, L.-X. Shi, Z.-N. Chen
2 H), 9.22 (d, J = 5.6 Hz, 2 H) ppm. 31P NMR (CD3CN): δ = 19.51 chromatography on silica gel by using CH2Cl2/acetone (5:1) as elu-
FULL PAPER
(s) ppm. C60H49Cl2N3O5P2RuS (1158.04): calcd. C 62.23, H 4.26,
N 3.63; found C 62.31, H 4.46, N 3.07.
ent. Yield 268 mg (87%). IR (KBr): ν = 1685 (m, C=O), 2160 [s
˜
(N, CN)2], 2225 {w [N(CN)2]}, 2264 {m [N(CN)2]}, 1089 [s,
(ClO4) ], 696 (s, P–C) cm–1. ESI-MS: m/z (%) = 1089 (100) [M –
[(AcSC6H4tpy)(PPh3)2RuCl](ClO4) {[9](ClO4)}: This compound
was obtained by desilylation of [(TMSESC6H4tpy)(PPh3)2RuCl]-
(ClO4) (100 mg, 0.08 mmol) according to Method II of the general
conversion using excess acetyl chloride (20 equiv.) and TBAF. Yield
1
ClO4]+. H NMR (CD3CN): δ = 2.39 (s, 3 H), 4.26 (s, 2 H), 7.03–
7.20 (m, 26 H), 7.30 (t, J = 7.4 Hz, 6 H), 7.58 (d, J = 8.3 Hz, 2 H),
7.72 (m, 6 H), 7.83 (d, J = 7.4 Hz, 2 H), 8.87 (d, J = 5.4 Hz, 2 H)
ppm. C62H49ClN6O5P2RuS·2H2O (1224.66): calcd. C 60.81, H
4.36, N 6.86; found C 60.35, H 4.89, N 6.83.
77 mg (80%). IR (KBr): ν = 1704 (m, C=O), 1088 (s, ClO ), 697
˜
4
(s, P–C) cm–1. ESI-MS: m/z (%) = 1044 (100) [M–ClO4]+. 1H NMR
(CD3CN): δ = 2.49 (s, 3 H), 7.08–7.27 (m, 32 H), 7.63 (s, 2 H),
7.68 (m, 4 H), 7.78 (d, J = 8.4 Hz, 2 H), 7.86 (d, J = 7.7 Hz, 2 H),
9.23 (d, J = 5.4 Hz, 2 H) ppm. C59H47Cl2N3O5P2RuS (1144.01):
calcd. C 61.94, H 4.14, N 3.67; found C 61.44, H 4.67, N 3.75.
[{(AcSCH2C6H4tpy)(PPh3)2Ru}2{μ-N(CN)2}](ClO4)3 {[14](ClO4)3}:
A
mixture of complex [13](ClO4) (100 mg, 0.08 mmol),
[(AcSCH2C6H4tpy)(PPh3)2RuCl](ClO4) (120 mg, 0.10 mmol), and
silver perchlorate (17 mg, 0.08 mmol) was stirred in acetone
(40 mL) at room temperature overnight. The solution was filtered
and the solvent evaporated in vacuo. The product was purified by
column chromatography on silica gel using CH2Cl2/acetone (4:1)
[(AcStpy)(PPh3)2RuCl](ClO4) {[10](ClO4)}: This compound was
obtained by desilylation of [(TMSEStpy)(PPh3)2RuCl](ClO4)
(100 mg, 0.09 mmol) according to Method II of the general conver-
sion using excess acetyl chloride (20 equiv.) and TBAF. Yield 38 mg
as eluent. Yield 153 mg (75%). IR (KBr): ν = 1686 (m, C=O), 2201
˜
{s [N(CN)2]}, 2306 {w [N(CN)2]}, 1088 (s, ClO4), 696 (s, P–C)
(41%). IR (KBr): ν = 1707 (m, C=O), 1088 (s, ClO ), 697 (s, P–C)
˜
4
cm–1. ESI-MS: m/z (%) = 1105 (100) [M – (ClO4)2]2+ 1H NMR
.
cm–1. ESI-MS: m/z (%) = 706 (100) [M – ClO4 – PPh3]+. 1H NMR
(CD3CN): δ = 2.58 (s, 3 H), 7.07–7.28 (m, 32 H), 7.50 (s, 2 H),
7.69 (d, J = 4.1 Hz, 4 H), 9.16 (d, J = 5.6 Hz, 2 H) ppm.
C53H43Cl2N3O5P2RuS·0.5H2O (1076.92): calcd. C 59.11, H 4.12, N
3.90; found C 59.06, H 4.15, N 3.91.
(CD3CN): δ = 2.40 (s, 6 H), 4.27 (s, 4 H), 7.07 (m, 44 H), 7.27 (m,
16 H), 7.51–7.78 (m, 20 H), 7.86 (d, J = 8.0 Hz, 4 H), 8.81 (s, 4 H)
ppm. 31P NMR (CD3CN):
δ
=
25.85 (s) ppm.
C122H98Cl3N9O14P4Ru2S2 (2410.66): calcd. C 60.78, H 4.10, N
5.23; found C 60.78, H 4.31, N 4.78.
[(TMSESCH2C6H4tpy)(PPh3)2Ru(CϵCC6H4CϵCC6H5)](ClO4)
{[11](ClO4)}: [(TMSESCH2C6H4tpy)(PPh3)2RuCl](ClO4) (0.20 g,
0.16 mmol) and silver perchlorate (0.034 g, 0.16 mmol) were dis-
solved in acetone (40 mL). The solution was refluxed under argon
in the dark. Upon cooling to room temperature, the solution was
filtered to remove the AgCl precipitate. After the solvent had been
removed in vacuo, 1-ethynyl-4-(phenylethynyl)benzene (0.043 g,
0.21 mmol), triethylamine (0.5 mL), and methanol (40 mL) were
subsequently added to the Schlenk flask. The solution was then
stirred under reflux for 1 d to give a brown residue by removing
the solvent in vacuo. The product was purified by column chroma-
tograph on silica gel using CH2Cl2/acetone (10:1) as eluent. Yield
Preparation of Self-Assembled Monolayers (SAMs) for Complex
[14](ClO4)3: A gold electrode was immersed into a CH2Cl2 solution
of [14](ClO4)3 (1 mm) and NEt3 (10 mm) for 2 d. The electrode was
taken out and rinsed thoroughly with CH2Cl2 and dried under ar-
gon before the measurements. The gold electrode modified with the
monolayer of [14](ClO4)3 was used as a working electrode for CV
measurements in a 0.1 m Bu4NPF6/CH2Cl2 solution.
Physical Measurements: IR spectra were recorded with a Magna
750 FT-IR spectrophotometer with KBr pellets. 1H, 13C, and 31P
NMR spectra were recorded with a Bruker Avance III-400 spec-
trometer with SiMe4 as the internal reference for 1H and 13C NMR
spectra, and H3PO4 as the external reference for 31P NMR spectra.
Elemental analyses (C, H, N) were carried out with a Perkin–Elmer
model 240C elemental analyzer. ESI-MS was performed with a
Finnigan LCQ mass spectrometer by using CH2Cl2/methanol mix-
tures as mobile phases. The cyclic voltammograms (CVs) were
made with a potentiostat/galvanostat model 263A in CH2Cl2 solu-
tions containing Bu4NPF6 (0.1 m) as the supporting electrolyte. The
CV measurements were performed at a scan rate of 100 mV s–1.
Platinum and glassy graphite were used as the counter and working
electrodes, respectively, and the potential was measured against an
Ag/AgCl reference electrode.
0.14 g (60%). IR (KBr): ν = 2051 (s, CϵC), 2207 (w, CϵC), 1246
˜
(w, Si–C), 1087 (s, ClO4), 696 (s, P–C) cm–1. ESI-MS: m/z (%) =
1281 (100) [M – ClO4]+. 1H NMR (CD3CN): δ = 0.05 (s, 9 H),
0.93 (m, 2 H), 2.58 (m, 2 H), 3.88 (s, 2 H), 7.05–7.49 (m, 39 H),
7.56 (m, 4 H), 7.64 (t, J = 7.4 Hz, 2 H), 7.72 (m, 4 H), 7.84 (d, J
= 7 . 6 H z , 2 H ) , 9 . 1 1 ( d , J = 5 . 6 H z , 2 H ) p p m .
C79H68ClN3O4P2RuSSi·CH2Cl2·H2O (1484.97): calcd. C 64.71, H
4.89, N 2.83; found C 64.57, H 4.92, N 3.05.
[(AcSCH2C6H4tpy)(PPh3)2Ru(CϵCC6H4CϵCC6H5)](ClO4)
{[12](ClO4)}: This compound was obtained by desilylation of
[(TMSESCH2C6H4tpy)(PPh3)2Ru(CϵCC6H4CϵCC6H5)](ClO4)
(11) (100 mg, 0.07 mmol) according to Method I of the general
conversion using excess acetyl chloride (10 equiv.) and AgClO4.
Crystal Structural Determination: Compound [14](PF6)3·
H2O·2C6H14 was prepared by the metathesis of perchlorate in
[14](ClO4)3 with potassium hexafluorophosphate, and crystals suit-
able for X-ray diffraction were grown by layering hexane onto the
CH2Cl2 solution. A single crystal sealed in a capillary with mother
liquor was measured with a Rigaku Mercury CCD diffractometer
by the ω-scan technique at room temperature with graphite-mono-
chromated Mo-Kα radiation (λ = 0.71073 Å). The CrystalClear
software package was used for data reduction and empirical ab-
sorption correction. The structure was solved by direct methods,
Yield 77 mg (80%). IR (KBr): ν = 2051 (s, CϵC), 2207 (w, CϵC),
˜
1685 (m, C=O), 1088 (s, ClO4), 696 (s, P–C) cm–1. ESI-MS: m/z
(%) = 1224 (100) [M–ClO4]+. 1H NMR (CDCl3): δ = 2.42 (s, 3 H),
4.22 (s, 2 H), 6.90 (m, 2 H), 7.05–7.40 (35 H), 7.44 (d, J = 8.2 Hz,
2 H), 7.55 (m, 4 H), 7.66 (d, J = 7.7 Hz, 2 H), 7.76 (m, 4 H), 7.99
(d, J = 8.0 Hz, 2 H), 8.83 (d, J = 5.3 Hz, 2 H) ppm. 31P NMR
(CDCl3): δ = 27.63 (s) ppm. C76H58ClN3O5P2RuS·2H2O (1359.86):
calcd. C 67.13, H 4.60, N 3.09; found C 67.29, H 5.06, N 2.98.
[{(AcSCH2C6H4tpy)Ru(PPh3)2}{N(CN)2}](ClO4)
{[13](ClO4)}: and the heavy atoms were located from an E-map. The remaining
[(AcSCH2C6H4tpy)(PPh3)2RuCl](ClO4) (300 mg, 0.26 mmol) and
sodium dicyanamide (69 mg, 0.78 mmol) were dissolved in meth-
anol (40 mL). After stirring under reflux for 6 h, the solution was
cooled to room temperature, and the solvent was removed in vacuo
to give a brown residue. The product was purified by column
non-hydrogen atoms were determined from the successive differ-
ence Fourier syntheses. All non-hydrogen atoms were refined aniso-
tropically, and the hydrogen atoms were generated geometrically
and refined with isotropic thermal parameters. The structure was
refined on F2 by full-matrix least-squares methods using the
1790
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Eur. J. Inorg. Chem. 2011, 1784–1791

Ruthenium(II) Complexes with Protected Terpyridine–Thiols
SHELXTL-97 program package.[25] CCDC-801789 contains the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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[13] The microwave irradiation synthesis of compound 4 was per-
formed by using a Biotage Initiator system. 4Ј-[(Trifluorome-
thyl)sulfono]-2,2Ј:6Ј,2ЈЈ-terpyridine (300 mg, 0.79 mmol), po-
tassium thioacetate (140 mg, 1.18 mmol), Pd2(dba)3 (18 mg,
0.02 mmol), and Xantphos (23 mg, 0.04 mmol) were added to
a microwave vial (2–5 mL) under argon. The vessel was charged
with iPr2NEt (0.26 mL, 1.58 mmol) and 1,4-dioxane (4 mL),
and sealed quickly with a microwave tube cap. Under micro-
wave radiation, the mixture was heated at 160 °C for 25 min.
The crude product was extracted with ethyl acetate, and the
organic layer was dried with MgSO4. The filtrate was concen-
trated and chromatographed on a silica gel column by using
hexane/CH2Cl2/ethyl acetate (8:3:2) as eluent. Yield 73 mg
(30%).
Supporting Information (see footnote on the first page of this arti-
cle): CV of complex 14 in solution, NMR spectra of compounds
1–7 and 14.
Acknowledgments
We are grateful for financial support from the National Natural
Science Foundation of China (NSFC) (20625101, 20773128,
20821061, and 20931006), the 973 Project (2007CB815304), from
the Ministry of Science and Technology of China (MSTC), and the
Natural Science Foundation (NSF) of Fujian Province (2008I0027).
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Received: November 30, 2010
Published Online: March 10, 2011
Eur. J. Inorg. Chem. 2011, 1784–1791
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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