Methyl-oxygen bond cleavage in hemilabile phosphine-ether ligand of ruthenium(II) complexes

Article abstract of DOI:10.1016/j.jorganchem.2009.01.032

The preparation and characterization are described for four ruthenium(II) complexes containing hemilabile phosphine-ether ligand o-(diphenylphosphino)anisole (Ph₂PC₆H₄OMe-o) and/or bidentate ligand diphenylphosphino-phenol

Full text of DOI:10.1016/j.jorganchem.2009.01.032

Journal of Organometallic Chemistry 694 (2009) 1912–1917
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Methyl–oxygen bond cleavage in hemilabile phosphine–ether ligand
of ruthenium(II) complexes
a
a
b
c
Sodio C.N. Hsu a, , Shih-Chieh Hu , Zih-Shing Wu , Michael Y. Chiang , Min-Yuan Hung
*
a Department of Medicinal and Applied Chemistry, and Center of Excellence for Environmental Medicine, Kaohsiung Medical University, No. 100, Tzyou 1st Road,
Kaohsiung 807, Taiwan
b Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
c Center for Resources, Research and Development, Kaohsiung Medical University, Kaohsiung 807, Taiwan
a r t i c l e i n f o
a b s t r a c t
Article history:
The preparation and characterization are described for four ruthenium(II) complexes containing hemila-
Received 13 October 2008
Received in revised form 16 January 2009
Accepted 20 January 2009
Available online 24 January 2009
bile phosphine–ether ligand o-(diphenylphosphino)anisole (Ph2PC6H4OMe-o) and/or bidentate ligand
diphenylphosphino-phenolate ([Ph2PC6H4O-o]À) Ru(RCN)2( 2-Ph2PC6H4O-o)2 (1a: R = Me; 1b: R = Et)
j
and [Ru(RCN)2(j j
2-Ph2PC6H4O-o)( 2-Ph2PC6H4OMe-o)](PF6) (2a: R = Me; 2b: R = Et). The ruthenium(II)
phosphine–ether complexes undergo mild methyl–oxygen bond cleavage. Two different kinds reaction
mechanism are proposed to describe the methyl–oxygen bond cleavage, one involving attack of anionic
nucleophiles and another involving the phosphine. The new reactions define novel routes to phosphine–
phenolate complexes. The structures of complexes 1a, 1b and 2a were confirmed by X-ray crystallography.
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
Ruthenium
Phosphine ligands
methyl–oxygen bond cleavage
Dealkylation
1. Introduction
metal center to form r-bonded aryloxide complexes [16,19,20].
Such ligand-assisted dealkylations proceed via nucleophilic attack
by the free ligand’s phosphorus to produce the stable alkylphos-
phonium salt, which drives the reaction [20]. Another dealkylation
pathway was suggested by the elimination of CH3Cl in the transi-
The insertion of transition-metal atoms into a carbon–oxygen
bond is proposed as key steps in the hydrodeoxygenation (HDO)
of crude oil and may lead to the design of novel catalytic reactions
[1]. The C–O bond cleavage reactions by transition-metal
complexes that involve either strained systems or relatively weak
C–O bonds, or systems driven by aromatization, are well known
[2–9]. For example, C–O bond cleavage of strained cyclic ethers
by transition-metals has been applied to catalysis of isomerization
to carbonyl compounds, coupling to form esters, and carbonylation
to lactones [2,6]. On the other hand, transition-metal complexes
contain monoanionic oxygen donor ligands, especially phospha-
nylphenoxides, are currently receiving considerable attention lar-
gely because of their potential use as homogeneous catalyst
precursors for polymerization of terminal olefins and ring-opening
polymerization of heterocyclic molecules [10–15].
tion-metal halide complexes [16]. The reactivity of RuCl2(j2
-
Ph2PC6H4OMe-o)2 (Ph2PC6H4OMe-o @ o-(diphenylphosphino)ani-
sole) has been reported with CO and isocyanide to give mono
and di-adducts, which do not perform dealkylation process
[21,22]. Herein, we set out to investigate the occurrence of
ligand-assisted dealkylation in
complex.
a RuCl2(j
2-Ph2PC6H4OMe-o)2
2. Results and discussion
2.1. Ether dealkylation reactions
The hemilabile phosphine–ether ligand and its Ru(II) complexes
also have received much attention due to their wide-range of util-
ity in homogeneous catalysis [16–18]. Studies of the coordination
chemistry of the Ru(II) complexes in particular containing hemila-
bile phosphine–ether ligands are useful in understanding the cata-
lytic activity of this class of compounds. These phosphine–ether
ligands are usually dealkylated when coordinated to transition-
Thermolysis of RuCl2(j
2-Ph2PC6H4OMe-o)2 in MeCN solvent re-
sults in dealkylation of the ether ligands. From this simple proce-
dure we obtained an excellent yield of the neutral compound
Ru(MeCN)2(
ylphosphino)phenolate)). On the other hand, heating MeCN solu-
tion of RuCl2(
2-Ph2PC6H4OMe-o)2 in the presence of KPF6
resulted in clean monodemethylation to give the yellow complex
[Ru(MeCN)2(
2-Ph2PC6H4O-o)( 2-Ph2PC6H4OMe-o)]PF6 (2a), to-
gether with 1a and small amounts of phosphonium ion
[Me(Ph2PC6H4OMe-o)]+ (Scheme 1).
j
2-Ph2PC6H4O-o)2 (1a) ([Ph2PC6H4O-o]À @ o-(diphen-
j
j
j
a
* Corresponding author. Tel.: +886 7 3121101; fax: +886 7 3125339.
E-mail address: sodiohsu@kmu.edu.tw (S.C.N. Hsu).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.01.032

S.C.N. Hsu et al. / Journal of Organometallic Chemistry 694 (2009) 1912–1917
1913
NCR
NCR
Cl
Ru
Cl
-
Ph Ph
P
Ph Ph
Ph Ph
P
Ph Ph
P
Ph Ph
P
Ph Ph
PF6
KPF6
RCN
P
P
Ru
Ru
+
O
Me
O
O
O
O
Me
O
Me
NCR
NCR
1a (R = Me)
1b (R = Et)
2a (R = Me)
2b (R = Et)
RCN
NCR
Ph Ph
P
Ph Ph
P
Ru
O
O
NCR
1a (R = Me)
1b (R = Et)
Scheme 1.
Compound 1a and 2a both contain two coordinated MeCN li-
gands which can be confirmed by 1H NMR, 13C{1H}NMR and IR
spectroscopy. Additionally each compound gave well-resolved
ESI-mass spectra with molecular ions. The 1H NMR spectrum of
1a shows a singlet at d 2.08 assigned to the coordinated MeCN.
Similarly, a signal for coordinated MeCN is also present in the 1H
NMR spectrum of 2a, in addition a singlet at d 4.60 assigned to
the methoxy group. The 13C{1H}NMR spectrum of 1a also shows
a methyl signal at d 2.96 and a nitrile signal at d 122.22, which
were assigned to the coordinated MeCN. To compare with 1a, the
13C{1H}NMR spectrum of 2a has an extra signal at d 61.23, which
is assigned to methoxy group of undealkylation phosphine–ether
ligand. The IR spectrum of 1a and 2a both exhibit a weak mCN band
at 2216 and 2260 cmÀ1 assigned to coordinated MeCN, respec-
tively. The 31P{1H} NMR spectrum of 1a appears only one peak at
d 60.32. The 31P{1H} NMR spectrum of 2a features two sets of dou-
blet resonances at d 55.3 and 64.4 in a 1:1 intensity ratio, which
may due to different phosphorus environment.
Analogous reactions occurred when the thermolysis of
RuCl2(
Ru(EtCN)2(
Ph2PC6H4O-o)(
j
2-Ph2PC6H4OMe-o)2 was conducted in EtCN solution, giving
j
2-Ph2PC6H4O-o)2 (1b) and, using KPF6, [Ru(EtCN)2(j2
-
j
2-Ph2PC6H4OMe-o)](PF6) (2b). Again in the later
case, the side products [Me(Ph2PC6H4OMe-o)]+ was obtained,
establishing that the source of the methyl group was the ether,
not the solvent. When excess KPF6 (30 equiv.) was applied in the
Table 1
Summarized results of reactions of RuCl2(
j
2-Ph2PC6H4OMe-o)2 with KPF6 as deter-
mined from experimental separationa and 1H NMR spectrab.
thermolysis reaction of RuCl2(j
2-Ph2PC6H4OMe-o)2, the amount
a1a
a1b
bCH3Cl
b[Me(POMe)]+
of CH3Cl decrease, and the amount of side product phosphonium
salt increase (Table 1). A possible explanation may be that the
potassium salt (KPF6) will inhibit the elimination of CH3Cl to form
the potassium chloride during the thermolysis process.
Without KPF6
With 2 equiv. KPF6
With 30 equiv. KPF6
88%
67%
38%
–
20%
30%
88%
66%
40%
–
6%
18%
+
Cl
Cl
Cl
+
Me
O
Ph Ph
P
Ph Ph
P
Ph Ph
P
Ph Ph
Ph Ph
P
Ph Ph
P
P
Ru
Ru
Cl
Ru
RCN
RCN
O
Me
O
Me
O
Me
O
Me
O
Me
NCR
NCR
NCR
m/z = 802.6
m/z = 761.6
Cl
+
+
Cl
Me
Ph Ph
P
Ph Ph
P
O
Ph Ph
PH
Ph Ph
P
Ru
Ru
O
O
Me
NCR
O
NCR
NCR
Me
Me
B
A
Cl-
RCN
RCN
Cl-
NCR
2 MeCl
2 MeCl
Ph Ph
P
Ph Ph
P
Ru
O
O
NCR
1a (R = Me)
1b (R = Et)
Scheme 2. Proposed reaction pathway for elimination of CH3Cl without KPF6.

1914
S.C.N. Hsu et al. / Journal of Organometallic Chemistry 694 (2009) 1912–1917
Cl
Ru
Cl
NCR
Ph Ph
P
Ph Ph
P
Ph Ph
P
Ph Ph
P
2 MeCl
Ru
RCN
O
Me
O
Me
O
O
NCR
1a (R = Me)
1b (R = Et)
KPF6
RCN
NCR
NCR
NCR
2+
Ph Ph
P
Ph Ph
Ph Ph
P
Ph Ph
Ph Ph
Ph Ph
P
P
P
P
free POMe
RCN
free POMe
RCN
Ru
Ru
Ru
O
O
O
O
O
O
Me
Me
Me
NCR
NCR
m/z = 383.8
NCR
1a (R = Me)
1b (R = Et)
+ [Me(POMe)]+
2a (R = Me)
2b (R = Et)
+ [Me(POMe)]+
- RCN
2+
Ph Ph
P
Ph Ph
P
Thermal decomposition
Ru
Ph
Ph
P
O
Me
O
Me
O
Me
free POMe
NCR
m/z = 363.2
Scheme 3. Probably reaction pathway for the demethylation process in presence of KPF6.
2.2. In situ studies of the dealkylation
(Fig. S4). The 31P{1H} NMR spectra data is also consistent with 1H
NMR results (Fig. S5). The reaction of pure 1a, MeCl (1 atm), and
KPF6 in CD3CN also carry out in a sealed NMR J-Young tube, which
do not give complex 2a (no reaction occur). On the other hand, the
pure 2a reacts with the free POMe ligand do give 1a, that was
proved by 31P NMR monitoring experiment (Fig. S6). This result ap-
pears the additional POMe ligand will assist the O-dealkylation on
the ruthenium(II) phosphine–ether complexes.
In attempts to examine the possible routes for the formation of
demethylation reactions, the thermolysis of RuCl2(j
2-Ph2PC6-
H4OMe-o)2 was carried out in a sealed NMR tube. Over the course
of hours at 80 °C, the 1H NMR spectra showed the formation of 1a
accompanied the elimination of two molecules of CH3Cl (d 3.05,
Fig. S2). Related changes were also observed in 31P{1H} NMR
spectra: the resonance for RuCl2(
j
2-Ph2PC6H4OMe-o)2 decreased
The thermolysis reaction in MeCN solution of RuCl2(j2
-
followed by an increase of the resonance at d 60.32 for 1a
(Fig. S3).
Ph2PC6H4OMe-o)2 was also examined by ESI-MS, which revealed
the formation of some important intermediates prior to dealkyla-
tion. The initial ESI-MS experiment of thermolysis MeCN solution
Different results were obtained when the thermolysis of
RuCl2(
j
2-Ph2PC6H4OMe-o)2 was conducted in presence of KPF6.
of RuCl2(
intermediate [RuCl(
and [RuCl(
1-Ph2PC6H4OMe-o)(
(m/z 802.6) (Fig. S7). According to the NMR data and ESI-MS
j
2-Ph2PC6H4OMe-o)2 without KPF6 give the dechlorinate
1H NMR spectra of showed the formation of 1a, 2a, and small
amounts of CH3Cl with a new doublet at d 2.75, which is assigned
to the formation of a phosphonium ion [Me(Ph2PC6H4OMe-o)]+
j
2-Ph2PC6H4OMe-o)2(NCMe)]+ (m/z 761.6)
2-Ph2PC6H4OMe-o)(NCMe)2]+
j
j
Fig. 1. Molecular structure of Ru(MeCN)2(
j
2-Ph2PC6H4O-o)2 (1a) with thermal
Fig. 2. Molecular structure of Ru(EtCN)2(j
2-Ph2PC6H4O-o)2 (1b) with thermal
ellipsoids drawn at the 50% level.
ellipsoids drawn at the 50% level.

S.C.N. Hsu et al. / Journal of Organometallic Chemistry 694 (2009) 1912–1917
1915
group. Similar ligand-assisted O-dealkylation are observed for the
Ru(II) complexes containing hemilabile phosphine–ether ligand
[20,23]. However, the pathway of ligand-assisted O-dealkylation
still remains unclearly. According to the initial ESI-mass experi-
ment and sealed NMR experiment results, we proposed probably
reaction pathway for the demethylation process in presence of
KPF6 (Scheme 3). The initial reaction is chloride dissociation to
form the dication intermediates [Ru(
(NCMe)2]2+ (m/z 383.8) and [Ru( 2-Ph2PC6H4OMe-o)2(NCMe)]2+
(m/z 363.2), which were proved by the initial ESI-mass experiment.
The following thermal decomposition of [Ru(
2-Ph2PC6H4OMe-o)2-
j
2-Ph2PC6H4OMe-o)2
j
j
(NCMe)]2+ may result in free phosphine ligand for the phospho-
nium ion formation. There are several probably pathway list in
Scheme 3 to explain the final thermolysis result in presence of
KPF6. The driving force of these pathways could come from the side
products formation of KCl, CH3Cl and phosphonium ion [Me(Ph2P-
C6H4OMe-o)]+. The formation of the phosphonium ion implies that
the side reaction arise from nucleophilic attack of the free phos-
phine on the carbon of the Ru-bound methoxy group. This pathway
is predominant when the reaction was conducted in the presence
of KPF6. The potassium salt (KPF6) may also inhibit the elimination
of CH3Cl, because of the formation of potassium chloride during
the thermolysis process.
Fig. 3. Molecular structure of the anion [Ru(MeCN)2(j j
2-Ph2PC6H4O-o)( 2-Ph2
PC6H4OMe-o)]+ (2a) with thermal ellipsoids drawn at the 50% level.
Table 2
Selected bond distances (Å) and angeles (deg) for Ru(CH3CN)2(
Ru(EtCN)2(
j
2-Ph2PC6H4O-o)2 (1a),
2.3. Crystallographic characterization of phosphinephenolates
j
2-Ph2PC6H4O-o)2 (1b) and [Ru(MeCN)2( 2-Ph2PC6H4O-o)(
j
j
2-Ph2PC6H4
OMe-o)]PF6 (2a).
The stereochemistry of 1a, 1b and 2a were determined by single
crystal X-ray diffraction analysis (Figs. 1–3; Table 2). The geometry
of these complexes is distorted octahedral. All nitrile ligands of 1a,
1b and 2a are nearly symmetrically in mutually trans position. The
Ru–P bond distances are near 2.27 Å, somewhat longer than those
1a
1b
2a
Ru–O
2.116(2)
2.132(2)
2.119(2)
2.125(2)
2.105(4)
Ru–OMe
Ru–NCMe
2.241(4)
2.004(5)
2.008(5)
2.255(17)
2.003(3)
2.013(3)
2.2663(9)
2.2734(10)
2.005(3)
2.014(3)
2.2769(8)
2.2660(9)
in the starting material RuCl2(j
2-Ph2PC6H4OMe-o)2 (2.217 Å) [21].
This effect arises from greater trans influence of the phenoxide ver-
sus the more weakly donating ether ligands trans to the phosphine.
The P–Ru–P angles are approximately 107°, presumably minimiz-
ing repulsive interactions between the phenyl groups. The O–Ru–
O angles are 20° more acute in 1a, 1b, and 2a. The Ph2PC6H4O-o li-
gand functions has a chelate bite angles P–Ru–O of 83.30°, slightly
larger than the P–Ru–OMe of 80.31° in 2a. Most significantly, the
Ru–O (phenoxide) distances of 2.116 Å and 2.132 Å in 1a, 2.119 Å
and 2.125 Å in 1b, and 2.105 Å in 2a are much shorter than Ru–O
(ether) bond distance of 2.241 Å in 2a and their starting material
Ru–PO
Ru–POMe
N–CMe
2.2800(8)
1.150(7)
1.154(7)
1.135(5)
1.141(5)
1.141(4)
1.136(5)
P–Ru–P
O–Ru–O
P–Ru–O
107.47(4)
86.86(10)
82.85(7)
82.84(7)
107.96(3)
86.00(8)
82.99(7)
83.06(6)
107.22(6)
89.21(15)
83.30(12)
P–Ru–OMe
80.31(11)
RuCl2(j
2-Ph2PC6H4OMe-o)2 (2.229 and 2.257 Å) [21]. In the mixed
ether-phenoxide complex 2a, Ru–OMe bond distance of 2.241 Å is
much longer than the sum of the covalent radii (1.99 Å), suggesting
that the oxygen atom of ether group is only weakly coordinated
[24]. In fact, complex 2a contains both Ru–O and Ru–OMe types
bonding mode in a complex that gives a good example to compare
the weak metal–ether bonds versus strong metal–phenoxide
bonds.
results, the proposed reaction pathway of elimination of CH3Cl is
depicted in Scheme 2. The elimination of CH3Cl may be via a
four-centered intermediate or transition state A and B. Similar
reaction pathway has been proposed [16]. On the other hand,
the addition of KPF6 to a MeCN solution of RuCl2(
OMe-o)2 was also found to rapidly give the monochloride cations
[RuCl(
2-Ph2PC6H4OMe-o)2(NCMe)]+ (m/z 761.6) and [RuCl(j1
Ph2PC6H4OMe-o)(
2-Ph2PC6H4OMe-o)(NCMe)2]+ (m/z 802.6) in
addition the momo-dealkylation product 2a (m/z 752.8) present
as major species. Interestingly, the dication intermediates [Ru(j2
Ph2PC6H4OMe-o)2(NCMe)2]2+ (m/z 383.8) and [Ru( 2-Ph2PC6H4
j
2-Ph2PC6H4-
j
-
j
3. Conclusions
-
Four ruthenium(II) complexes containing hemilabile phos-
phine–ether ligand o-(diphenylphosphino)anisole (Ph2PC6H4-
OMe-o) and/or bidentate ligand diphenylphosphino–phenolate
have been synthesized and characterized in order to examine the
possible routes for the methyl–oxygen bond cleavage. Two differ-
ent kinds reaction mechanism are proposed to describe the
methyl–oxygen bond cleavage, one involving the elimination of
CH3Cl molecule and another involving the formation of the phos-
phonium ion. It is first time to observe the elimination of CH3Cl
and the formation of the phosphonium ion in a reaction, which
may provide us a good example to study the condition of ligand-as-
sisted O-dealkylation of transition-metal complexes.
j
OMe-o)2(NCMe)]2+ (m/z 363.2) were only found in the presence
of KPF6 ESI-MS experiment. These initial ESI-mass experiments,
which exhibited the corresponding molecular peaks at m/z 761.6,
802.6 and the dication interimediates peaks (m/z 383.8 and
363.2), provided critical data and confirmation of the reaction
intermediates. These results indicate the potassium cation may
play an important role in the formation of monodemethylation
product 2a.
The presence of the phosphonium ion in reaction products im-
plies that the side reaction comes from the nucleophilic attack of
the free phosphine ligand on the carbon of the Ru-bound methoxy

1916
S.C.N. Hsu et al. / Journal of Organometallic Chemistry 694 (2009) 1912–1917
crystals of [Ru(CH3CN)2(j j
2-Ph2PC6H4O-o)( 2-Ph2PC6H4OMe-o)]-
4. Experimental
(PF6) (2a). Yield: 85 mg (20%). The yellow filtration solid was
extracted into 10 mL of CH2Cl2 followed by addition of 100 mL of
All manipulations were carried out under an atmosphere of
purified dinitrogen with standard Schlenk techniques. Chemical re-
agents were purchased from Aldrich Chemical Company Ltd., Lan-
caster Chemicals Ltd., or Fluka Ltd. All the reagents were used
without further purification, apart from all solvents that were
dried over Na (Et2O, hexane, THF) or CaH2 (CH2Cl2, CH3CN) or dried
via filtration through activated alumina then thoroughly degassed
ether to give
(1a). Yield: 235 mg (67%). trans-[Ru(CH3CN)2(
o)(
2-Ph2PC6H4OMe-o)](PF6) (2a): IR (KBr, cmÀ1):
a yellow product Ru(MeCN)2(j
2-Ph2PC6H4O-o)2
j
2-Ph2PC6H4O-
mCN = 2260 (w).
j
1H NMR (DMSO-d6): d 2.08 (s, 6H, CH3CN), 4.60 (s, 3H, -OCH3),
6.95–7.90 (m, 28H, Ph). 13C{1H}NMR (DMSO-d6): d 9.55 (CH3CN),
61.23 (-OCH3), 125.43 (CH3CN), 112.62–179.02 (Ph). 31P{1H}NMR
(DMSO-d6): d 64.45 (d, JPP = 60 Hz), 55.32 (d, JPP = 60 Hz). ESI-MS
(m/z): 753.2 (M+). Anal. Calc. for C41H37F6N2O2P3Ru: C, 54.85; H,
4.15; N, 3.12. Found: C, 54.96; H, 4.19; N, 3.25%.
before use. RuCl2(j
2-Ph2PC6H4OMe-o)2 were prepared according to
literature procedures [21]. IR spectra were recorded on a Perkin–
Elmer System 2000 FTIR spectrometer. 1H and 31P NMR spectra
were acquired on a Varian Gemini-500 proton/Carbon FT NMR
spectrometer at 500 and 202.4 MHz, respectively. ESI-MS were col-
lected on a Quattro quadrupole–hexapole–quadrapole (QHQ) mass
spectrometer. Elemental analyses were performed by by the Na-
tional Science Council Regional Instrumentation Center at National
Chen-Kung University, Tainan, Taiwan.
4.3. Thermolysis of RuCl2(
j
2-Ph2PC6H4OMe-o)2 in EtCN
A
solution of 360 mg (0.48 mmol) of RuCl2(j
2-Ph2PC6H4-
OMe-o)2 was refluxed in 30 mL of EtCN for 4 h. The color of the
reaction mixture changed from red to yellow with yellow sus-
pended solid. The yellow solid was collected by filtration to give a
yellow product Ru(EtCN)2(j
2-Ph2PC6H4O-o)2 (1b). Yield: 308 mg
4.1. Thermolysis of RuCl2(
j
2-Ph2PC6H4OMe-o)2 in MeCN
(84%). 1H NMR (CD2Cl2): d 0.47 (t, 6H, CH3CH2CN), 1.85 (q, 4H,
CH3CH2CN), 6.43–7.31 (m, 28H, Ph). 13C{1H}NMR (CD2Cl2): d 9.55
(CH3CH2CN), 12.94 (CH3CH2CN), 125.12 (CH3CH2CN), 112.62–
179.02 (Ph) 31P{1H}NMR (CD2Cl2): d 59.24(s). ESI-Mass (m/z):
767.6 ([M+H]+), 711.19 ([MÀEtCN+H]+). Anal. Calc. for C42H38N2O2-
P2Ru: C, 65.87; H, 5.00; N3.66. Found: C, 65.83; H, 5.11; N, 3.58%.
A
solution of 360 mg (0.48 mmol) of RuCl2(j
2-Ph2PC6H4-
OMe-o)2 was refluxed in 30 mL of CH3CN for 4 h. The color of the
reaction mixture changed from red to yellow with yellow sus-
pended solid. The yellow solid was collected by filtration to give
a
yellow product Ru(MeCN)2(
309 mg (88%). IR (KBr, cmÀ1): CN = 2216(w). 1H NMR (DMSO-d6):
d 2.08 (s, 6H, CH3CN), 4.60 (s, 3H, -OCH3), 6.95–7.90 (m, 28H, Ph).
j
2-Ph2PC6H4O-o)2 (1a). Yield:
m
4.4. Thermolysis of RuCl2(
j
2-Ph2PC6H4OMe-o)2 with KPF6 in EtCN
13C{1H}NMR (DMSO-d6):
d 2.96 (CH3CN), 122.22 (CH3CN),
2-Ph2PC6H4OMe-o)2
112.41–179.66 (Ph). 31P{1H}NMR (CD2Cl2): d 60.40(s). ESI-MS (m/
z): 739.4 ([M+H]+), 698.3 ([MÀ(CH3CN)+H]+), 657.2 ([MÀ(CH3-
CN)2+H]+). Anal. Calc. for C40H34N2O2P2RuCH2Cl2: C, 59.86; H,
4.41; N, 3.41. Found: C, 59.78; H, 4.49; N, 3.46%.
A solution of 360 mg (0.48 mmol) of RuCl2(
g
and 176 mg (0.96 mmol) of KPF6 was refluxed in 30 mL of EtCN for
18 h. The color of the reaction mixture changed from red to yellow
with yellow and white suspended solid. The yellow filtrate collected
by filtration and reduced ca. 3 mL under vacuum, followed by the
addition of 50 mL of ether to give yellow microcrystals of
4.2. Thermolysis of RuCl2(
j
2-Ph2PC6H4OMe-o)2 with KPF6 in MeCN
[Ru(EtCN)2(j j
2-Ph2PC6H4O-o)( 2-Ph2PC6H4OMe-o)](PF6) (2b). Yield:
A
solution of 360 mg (0.48 mmol) of RuCl2(
j
2-Ph2PC6H4-
133 mg (30%). The yellow filtration solid was extracted into 10 mL
of CH2Cl2 followed by addition of 100 mL of ether to give a yellow
OMe-o)2 and 176 mg (0.96 mmol) of KPF6 was refluxed in 30 mL
of CH3CN for 18 h. The color of the reaction mixture changed from
red to yellow with yellow and white suspended solid. The yellow
filtrate collected by filtration and reduced ca. 3 mL under vacuum,
followed by the addition of 50 mL of ether to give yellow micro-
product Ru(EtCN)2(
trans-[Ru(EtCN)2(
j
2-Ph2PC6H4O-o)2 (1b). Yield: 184 mg (50%).
j
2-Ph2PC6H4O-o)( 2-Ph2PC6H4OMe-o)](PF6) (2b):
j
1H NMR (DMSO-d6): d 1.14 (t, 6H, CH3CH2CN), 2.10 (q, 4H, CH3
CH2CN), 4.38 (s, 3H, -OCH3), 6.35–7.42 (m, 28H, Ph). 13C{1H}NMR
Table 3
Crystallographic data for Ru(CH3CN)2(
j
2-Ph2PC6H4O-o)2 (1a), Ru(EtCN)2(
j
2-Ph2PC6H4O-o)2 (1b) and [Ru(MeCN)2(
j
2-Ph2PC6H4O-o)(
j
2-Ph2PC6H4OMe-o)]PF6 (2a).
2a Á CH3CN
1a Á 3CH2Cl2
1b Á CH3OH
Empirical formula
Formula weight
T (K)
C43H40C16N2O2P2Ru
992.48
193(2)
C45H50N2O5P2Ru
861.88
200(2)
C43H40F6N3O2P3Ru
939.13
293(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Triclinic
P1
Monoclinic
P21/c
16.7345(2)
12.9796(2)
19.4951(3)
90
95.2900(10)
90
4216.44(10)
4
Monoclinic
P21/c
9.863(2)
22.457(5)
19.373(4)
90
101.51(3)
90
4204.8(15)
4
ꢀ
9.6937(5)
14.2709(7)
16.5212(8)
100.690(3)
100.348(3)
91.795(3)
2204.37(19)
2
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g cmÀ3
)
1.495
0.830
1.358
0.494
1.464
0.138
l
(mmÀ1
)
Reflections measured/independent
Data/restraints/parameters
Goodness-of-fit
27536/9075
9075/102/563
1.098
36023/7423
7423/0/500
1.192
51952/7990
7990/0/509
0.885
Rint
0.0463
0.0443
0.1712
R1 [I > 2
Rw [I > 2
Maximum peak/hole (eÀ/Å3)
r
r
] (all data)
] (all data)
0.0439 (0.0755)
0.1022 (0.1209)
0.910/À1.050
0.0419 (0.0579)
0.1090 (0.1305)
0.944/À0.946
0.0519 (0.1382)
0.1208 (0.1508)
0.933/À0.421

S.C.N. Hsu et al. / Journal of Organometallic Chemistry 694 (2009) 1912–1917
1917
(DMSO-d6): d 9.55 (CH3CN), 12.94 (CH3CH2CN), 60.45 (-OCH3),
Appendix A. Supplementary material
124.56 (CH3CH2CN), 112.62–179.02 (Ph). 31P{1H}NMR (MeCN-d3):
d 64.12 (d, JPP = 24.2 Hz), 54.45 (d, JPP = 36 Hz). ESI-Mass (m/z):
781.2 (M+), 726.2 ([M–EtCN]+). Anal. Calc. for C43H41F6N2O2P3Ru:
C, 55.79; H, 4.46; N, 3.03. Found: C, 55.74; H, 4.39; N, 3.15%.
CCDC 701446, 701447 and 701448 contain the supplementary
crystallographic data of compounds 1a, 1b and 2a for this paper.
These data can be obtained free of charge from the Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif. Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.
2009.01.032.
4.5. Preparation of phosphonium salt [Me(POMe)]I
An excess of MeI (0.20 mL, 3.22 mmol) was added to a solution
of 2-methoxyphenyldiphenylphosphine (0.20 g, 0.673 mmol) in
dry diethyl ether (25 mL) under nitrogen. The mixture immediately
became cloudy upon formation of the insoluble phosphonium salt.
The mixture was stirred for 5 h then evaporated to dryness to re-
move excess MeI. The residue was suspended in ether and the
white powder collected by filtration, washed with ether and hex-
anes, and dried under vacuum. Yield: 96%. 31P{1H} NMR (MeCN-
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Acknowledgements
We gratefully acknowledge the financial support of the National
Science Council (Taiwan). We thank Mr. Ting-Shen Kuo (National
Taiwan Normal University) for solving the X-ray structure of
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Ru(EtCN)2(
ful discussions.
j
2-Ph2PC6H4O-o)2(1b) and Prof. T.B. Rauchfuss for help-