Coordination study of ruthenium(II) complexes containing a mixed donor (P-N) ligand

Article abstract of DOI:10.1016/j.poly.2011.12.032

A series of ruthenium(II) complexes containing an o-(diphenylphosphino) aniline (P-N) ligand have been prepared to elucidate the geometric coordination isomers and substitution reactions. Thus, [(P-N)RuCl₂(CO) ₂] (1), [(P-N)RuCl₂(dmso)₂] (2) and [(P-N)RuCl₂(PPh₃)] (3) were synthesized by the reactions of various Ru(II) precursors with P-N. Treatment of 2 with CH₃CN yielded the substitution product [(P-N)RuCl₂(dmso)(CH₃CN)] (4). The rate of the dmso ligand self-exchange of 2 was investigated, and ΔG^≠ was estimated to be 23.7 kcal/mol, whereas ΔG ^≠ for the CH₃CN ligand self-exchange of 4 was 25 kcal/mol. Replacement of CO in 1 with dmso directly yielded [(P-N)RuCl ₂(dmso)(CO)] (8). Of course, complex 8 could also be prepared by substitutions of 2 and 4 with CO, but through various intermediates. Furthermore, the substitution reaction of 3 with CO and dmso led to the formation of 8, and complexes 2 and 3 were inter-convertible. The stereochemistry of all the Ru(II) complexes has been established by elemental, spectroscopic and X-ray crystal structural analyses.

Full text of DOI:10.1016/j.poly.2011.12.032

Polyhedron 35 (2012) 23–30
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Coordination study of ruthenium(II) complexes containing a mixed donor
(P–N) ligand
⇑
Chun-Chin Lee, Yi-Hung Liu, Shie-Ming Peng, Pi-Tai Chou, Jwu-Ting Chen, Shiuh-Tzung Liu
Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of ruthenium(II) complexes containing an o-(diphenylphosphino)aniline (P–N) ligand have been
prepared to elucidate the geometric coordination isomers and substitution reactions. Thus, [(P–N)
RuCl2(CO)2] (1), [(P–N)RuCl2(dmso)2] (2) and [(P–N)RuCl2(PPh3)] (3) were synthesized by the reactions
of various Ru(II) precursors with P–N. Treatment of 2 with CH3CN yielded the substitution product
[(P–N)RuCl2(dmso)(CH3CN)] (4). The rate of the dmso ligand self-exchange of 2 was investigated, and
Received 24 September 2011
Accepted 19 December 2011
Available online 17 January 2012
D
G– was estimated to be 23.7 kcal/mol, whereas G– for the CH3CN ligand self-exchange of 4 was
D
Keywords:
Phosphine
Amine
Ruthenium
Ligand substitution
Mixed donor
25 kcal/mol. Replacement of CO in 1 with dmso directly yielded [(P–N)RuCl2(dmso)(CO)] (8). Of course,
complex 8 could also be prepared by substitutions of 2 and 4 with CO, but through various intermediates.
Furthermore, the substitution reaction of 3 with CO and dmso led to the formation of 8, and complexes 2
and 3 were inter-convertible. The stereochemistry of all the Ru(II) complexes has been established by
elemental, spectroscopic and X-ray crystal structural analyses.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
2. Experimental
The development of phosphorus-containing ligands has played
an important role in homogeneous catalysis. Although phosphines
still dominate the field of late transition metal-based catalysis,
there is growing interest in the search for new catalysts with
unsymmetrical bidentate ligands, particularly with phosphorus–
nitrogen (P–N) donors [1–12]. Unlike the symmetrical counter-
parts, the trans-effect natures of phosphorus and nitrogen are
expected to influence the binding properties of the substrates
around the metal center, which might manipulate the activity of
the catalysts [1–12]. Ruthenium complexes containing P–N ligands
have been established on complexation [13–24], but few investiga-
tions involve the coordination study of related ruthenium(II)
species with P–N ligands.
We have found that palladium complexes containing P–N li-
gands (Chart 1) showed unusual properties in controlling the inser-
tions of alkene, alkyne and/or CO, providing an understanding of
ligand effects [25–29]. Compared to the four-coordinated palla-
dium species, the coordination variety of ruthenium ions is rather
complicated. Continuing the study of ligand effects, we explore the
coordination chemistry of P–N toward Ru(II).
2.1. Methods and materials
All reactions, manipulations and purifications steps were per-
formed under a dry nitrogen atmosphere. Tetrahydrofuran was
distilled under nitrogen from sodium benzophenone ketyl. Dichlo-
romethane and acetonitrile were dried over CaH2 and distilled un-
der nitrogen. Other chemicals and solvents were of analytical grade
and were used after the degassing process. The ligand P–N [30],
[RuCl2(dmso)4] [31], [RuCl2(CO)3(THF)] [32] and [RuCl2(PPh3)3]
[33] were prepared accordingly to the method reported previously.
Nuclear magnetic resonance spectra were recorded in CDCl3 or
acetone-d6 on a Bruker AVANCE 400 spectrometer. Chemical shifts
are given in parts per million relative to Me4Si for 1H and 13C NMR,
and relative 85% H3PO4 for 31P NMR. Infrared spectra were mea-
sured on a Nicolet Magna-IR 550 spectrometer (Series-II) as KBr
pellets, unless otherwise noted.
2.2. Synthesis and characterization
2.2.1. Complex 1
A mixture of P–N (100 mg, 0.36 mmol) and RuCl2(CO)3(THF)
(118 mg, 0.36 mmol) in anhydrous THF (3 mL) was heated to reflux
for 6 h. During the reaction, white solids precipitated, which were
collected by filtration and washed with ether (1 mL ꢀ 3). The de-
sired complex was obtained as yellow solids (k158 mg, 87%): IR
⇑
Corresponding author. Tel.: +886 2 2366 0352; fax: +886 2 2363 6359.
E-mail address: stliu@ntu.edu.tw (S.-T. Liu).
(KBr, cmꢁ1): 2058, 1996 ( CO). 1H NMR (400 MHz, d6-dmso) d:
m
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.12.032

24
C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
1.67 (s, 3H, CH3CN). 31P NMR (161 MHz, CDCl3) d: 63.0. 13C NMR
PPh2
OH
PPh2
PPh2
PPh2
NH2
(100 MHz, CDCl3) d: 148.4 (d, JC–P = 17.0 Hz, C–NH2), 134.6 (d,
JC–P = 9.0 Hz), 134.1 (d, JC–P = 46.0 Hz), 133.2, 132.8 (d,
JC–P = 10.0 Hz), 132.4 (d, JC–P = 48.0 Hz), 131.6, 130.4, 129.5, 128.2
(d, JC–P = 10.0 Hz), 127.9 (d, JC–P = 10.0 Hz), 127.9 (d, JC–P = 6.0 Hz),
127.1 (d, JC–P = 6.0 Hz), 123.0 (CH3CN), 46.5 (dmso), 46.3 (dmso),
4.6 (CH3CN). HR-ESI-MS m/z: 574.0422 ([MꢁCl]+, calc. for
N
N
N
Me
Ph
P–N
P–N–O
P–N=CPh
P–N=CMe
C24H28ClN3OPRuS: 574.0423). Anal. Calc. for C22H25Cl2N2OPRuS:
Chart 1. Some P–N type ligands.
C, 46.48; H, 4.43; N, 4.93. Found: C, 46.06; H, 4.46; N, 4.62.
2.2.5. Complex 5
8.11 (d, 1H, JH–H = 12 Hz, NH–), 7.88 (dd, 2H, J = 8.0 Hz, J = 12.0 Hz,
Ar H), 7.76 (m, 1H, Ar H), 7.69–7.47 (m, 9H, Ar H), 7.30 (m, 2H, Ar
H), 6.70 (d, 1H, JH–P = 12 Hz, NH–); 31P NMR (161 MHz, d6-dmso) d:
53.9; 13C NMR (100 MHz, d6-dmso) d: 195.8 (d, JC–P = 12.0 Hz, CO),
191.4 (d, JC–P = 11.0 Hz, CO), 150.6 (d, JC–P = 18.0 Hz, C–NH2), 134.9
(d, JC–P = 57.0 Hz), 134.7 (d, JC–P = 10.0 Hz), 133.3, 133.2, 132.3,
131.7, 131.6 (d, JC–P = 10.0 Hz), 129.8 (d, JC–P = 11.0 Hz), 129.0 (d,
JC–P = 11.0 Hz), 128.8 (d, JC–P = 3.0 Hz), 128.7 (d, JC–P = 10.0 Hz),
128.3 (d, JC–P = 6.0 Hz), 127.8 (d, JC–P = 7.0 Hz). Anal. Calc. for
Complex 3 (50 mg, 0.07 mmol) in CH2Cl2 (3 mL) was treated
with an atmospheric pressure of carbon monoxide with stirring
at room temperature for 3 days. Addition of ether to the above
solution readily provided dark-green solids as the desired product
(41 mg, 78%): IR (KBr, cmꢁ1): 1959 ( CO). 1H NMR (400 MHz, CDCl3)
m
d: 8.11 (m, 6H, Ar H), 7.99 (m, 2H, Ar H), 7.89 (m, 1H, Ar H), 7.64 (m,
4H, Ar H), 7.48–7.30 (m, 15H, Ar H), 6.56 (m, 1H, Ar H), 4.40 (d, 1H,
JH–H = 12 Hz, NH–), 2.78 (d, 1H, JH–H = 12 Hz, NH–). 31P NMR
(161 MHz, CDCl3) d: 34.9 (d, JP–P = 355 Hz), 21.9 (d, JP–P = 355 Hz).
13C NMR (100 MHz, CDCl3/CD2Cl2 = 1:1) d: 199.8 (t, JC–P = 13.5 Hz,
C20H16Cl2NO2PRu: C, 47.54; H, 3.19; N, 2.77; Found: C, 47.23; H,
2.99; N, 2.47.
CO), 148.9 (d, JC–P = 16.0 Hz, C–NH2), 134.9, 134.8 (d, JC–P
=
9.9 Hz), 134.2 (d, JC–P = 9.8 Hz), 133.3 (d, JC–P = 40.6 Hz), 132.9 (d,
JC–P = 9.8 Hz), 132.2, 131.5 (d, JC–P = 41.0 Hz), 130.8, 130.6, 130.4,
129.5 (d, JC–P = 4.5 Hz),128.9 (d, JC–P = 9.1 Hz), 128.7 (d,
JC–P = 9.8 Hz), 128.2 (d, JC–P = 9.9 Hz), 128.2 (d, JC–P = 4.5 Hz), 125.5
(d, JC–P = 9.9 Hz), 47.4 (dmso). Anal. Calc. for C37H31Cl2NOP2Ru: C,
60.09; H, 4.22; N, 1.89. Found: C, 59.70; H, 4.37; N, 1.73.
2.2.2. Complex 2
A mixture of P–N (100 mg, 0.36 mmol) and RuCl2(dmso)4
(174 mg, 0.36 mmol) in anhydrous THF (3 mL) was heated to reflux
for 6 h. During the reaction, yellow solids precipitated, which were
collected by filtration and washed with acetone. The desired com-
plex was obtained as yellow solids (181 mg, 83%): 1H NMR
(400 MHz, CDCl3) d: 7.89 (dd, 2H, JH–H = 8.0 Hz, JH–H = 12.0 Hz,
Ar–H), 7.76 (dd, 2H, JH–H = 8.0 Hz, JH–H = 12.0 Hz, Ar H), 7.66 (dd,
1H, JH–H = 4.0 Hz, JH–H = 8.0 Hz, Ar–H), 7.57–7.27 (m, 9H, Ar H),
6.35 (d, 1H, JH–H = 12 Hz, NH–), 5.64 (d, 1H, JH–H = 12 Hz, NH–),
3.47 (s, 3H, dmso), 3.39 (s, 3H, dmso), 3.01 (s, 3H, dmso), 2.11 (s,
3H, dmso). 31P NMR (161 MHz, CDCl3) d: 54.3. 13C NMR
(100 MHz, CDCl3) d: 149.0 (d, JC–P = 16.0 Hz, C–NH2), 135.1 (d, JC–
P = 9.0 Hz), 134.4, 133.9 (d, JC–P = 9.0 Hz), 133.0 (d, JC–P = 45.0 Hz),
132.3, 132.0 (d, JC–P = 48.0 Hz), 131.0, 130.2, 128.9 (d, JC–
P = 10.0 Hz), 127.6 (d, JC–P = 10.0 Hz), 127.4 (d, JC–P = 6.0 Hz), 127.3
(d, JC–P = 14.0 Hz), 48.5 (dmso), 47.7 (dmso), 47.3 (dmso), 45.6
(dmso). HR-ESI-MS m/z: 611.0292 ([MꢁCl+CH3CN]+, calc. for
2.2.6. Complex 6
Complex 4 (50 mg, 0.09 mmol) in CDCl3 (1 mL) was placed in a
100 mL bomb and then pressurized with CO (150 psi). The mixture
was stirred at an ambient temperature for 3 days. Addition of ether
caused the precipitation of light yellow solids (37 mg, 73%): Con-
ductivity: 86.1 ohmꢁ1 cm2 molꢁ1 (3.6 ꢀ 10ꢁ4 M in CH3OH, 27 °C).
IR (KBr, cmꢁ1): 2045 ( CO). 1H NMR (400 MHz, CDCl3) d: 9.68 (d,
m
1H, JH–H = 12 Hz, NH–), 7.83–7.19 (m, 14H, Ar H), 5.51 (d, 1H, JH–
H = 12 Hz, NH–), 3.33 (s, 3H, dmso), 2.91 (s, 3H, dmso), 1.83 (s,
3H, CH3CN). 31P NMR (161 MHz, CDCl3) d: 36.5. 13C NMR
(100 MHz) d: 191.4 (d, JC–P = 111.0 Hz, CO), 149.6 (d, JC–
P = 20.8 Hz), 134.2 (d, JC–P = 9.5 Hz), 133.7 (d, JC–P = 10.2 Hz),
133.2, 131.4 (d, JC–P = 2.9 Hz), 130.8 (d, JC–P = 2.5 Hz), 128.9 (d, JC–
P = 9.7 Hz), 128.9, 128.6 (d, JC–P = 10.4 Hz), 128.4 (d, JC–P = 5.3 Hz),
128.1 (d, JC–P = 31.9 Hz), 127.7 (d, JC–P = 6.1 Hz), 127.36 (d, JC–
P = 32.8 Hz), 126.9 (d, JC–P = 46.5 Hz), 51.2 (dmso), 46.6 (dmso),
5.0 (CH3CN). Anal. Calc. for C23H25Cl2N2O2PRuS + (CH3SOCH3): C,
44.51; H, 4.63; N, 4.15. Found: C, 44.85; H, 4.48; N, 4.33.
C24H31ClN2O2PRuS2: 611.0297). Anal. Calc. for C22H28Cl2NO2PRuS2:
C, 43.64; H, 4.66; N, 2.31. Found: C, 43.40; H, 4.77; N, 1.91.
2.2.3. Complex 3
A
mixture of P–N (100 mg, 0.36 mmol) and RuCl2(PPh3)3
(345 mg, 0.36 mmol) in THF (3 mL) was heated to reflux for 6 h.
After completion of the reaction, the solvent was removed and
the residue was washed with ether several times to remove tri-
phenylphosphine. The desired complex was precipitated by the
addition of acetone to an ether solution as dark-green solids
(133 mg, 52%). Due to the fluxional nature of the complex, the
NMR data was too complicated to be analyzed. HR-ESI-MS m/z:
717.0921 ([MꢁCl+MeCN]+, calc. for C38H34ClN2P2Ru: 717.0929),
Anal. Calc. for C36H31Cl2NP2Ru: C, 60.77; H, 4.39; N, 1.97. Found:
C, 60.60; H, 4.36; N, 1.68.
2.2.7. Complexes 7 and 8
Complex 2 (50 mg, 0.08 mmol) in CH2Cl2 (3 mL) was placed in a
100 mL bomb and then pressurized with CO (150 psi). The mixture
was stirred at an ambient temperature for 5 days. After releasing
the CO, the reaction mixture was centrifuged and decanted to yield
white solids as complex 8 (21 mg, 47%). Addition of ether to the
solution portion gave light yellow solids as complex 7 (22 mg,
48%). Complex 7: IR (KBr, cmꢁ1): 1996 ( CO). 1H NMR (400 MHz,
m
CDCl3) d: 7.61 (t, 2H, JH–H = 10 Hz, Ar–H), 7.44 (m, 1H, Ar H),
7.35–7.18 (m, 11H, Ar H), 6.15 (s, 2H, NH–), 3.07 (s, 6H, dmso).
31P NMR (161 MHz, CDCl3) d: 32.5. 13C NMR (100 MHz, CDCl3) d:
194.8 (d, JC–P = 118.0 Hz, CO), 149.2 (d, JC–P = 22.0 Hz, C–NH2),
134.4, 134.0 (d, JC–P = 10.0 Hz), 131.4, 129.7 (d, JC–P = 1.0 Hz),
2.2.4. Complex 4
Complex 2 (100 mg, 0.2 mmol) was placed in a 50 mL flask and
degassed. A mixed solution of THF and acetonitrile (V:V = 1:1) was
then syringed into the above vessel. The resulting solution was
heated to reflux for 6 h. Upon concentration, yellow precipitates
were formed and collected (77 mg, 72%): 1H NMR (400 MHz,
CDCl3) d: 7.89 (m, 2H Ar–H), 7.77 (m, 1H Ar–H), 7.61 (m, 2H),
7.26–7.47 (m, 9H, Ar–H), 5.93 (d, 1H, JH–H = 14 Hz, –NH), 4.71 (d,
1H, JH–H = 14 Hz, –NH), 3.35 (s, 3H, dmso), 2.99 (s, 3H, dmso),
129.0 (d, JC–P = 44.0 Hz), 128.8 (d, JC–P = 40.0 Hz), 127.4 (d, JC–P
=
10.0 Hz), 126.8 (d, JC–P = 6.0 Hz), 126.6 (d, JC–P = 9.0 Hz), 47.4
(dmso). Anal. Calc. for C21H22Cl2NO2PRuS: C, 45.41; H, 3.99; N,
2.52. Found: C, 45.68; H, 4.03; N, 2.34. Complex 8: IR (KBr,
cmꢁ1): 1994 ( CO). 1H NMR (400 MHz, dmso-d6) d: 7.80 (m, 2H,
m

C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
25
Table 1
Crystal data of 1ꢂ4(dmso), 4ꢂ(CH3CN) and 7.
Complex
1
4
7
Formula
C
28H40Cl2NO6PRuS4
C24H28Cl2N3OPRuS
609.49
C21H22Cl2NO2PRuS
555.40
monoclinic
C2/c
12.5778(2)
15.8799(3)
22.7847(4)
90
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
817.79
triclinic
P1
9.5744(3)
13.0231(4)
monoclinic
C2/c
33.5757(8)
8.9576(2)
18.0810(4)
90
ꢀ
15.2123(3)
89.620(2)
a
(°)
b (°)
76.923(2)
76.432(2)
1793.88(9), 2
1.514
840
92.180(2)
90
5434.1(2), 8
1.490
101.794(2)
90
4454.81(13)
1.656
c
(°)
V (Å3), Z
d (calc.) (mg/m3)
F(000)
2480
2240
Crystal size (mm)
Reflections collected
Independent reflections
h range (°)
0.20 ꢀ 0.15 ꢀ 0.10
0.25 ꢀ 0.20 ꢀ 0.15
0.25 ꢀ 0.20 ꢀ 0.15
23117
32476
26198
8222 [Rint = 0.0376]
2.75–27.50
6234 [Rint = 0.0338]
3.10–27.50
5111 [Rint = 0.0189]
3.15–27.50
Refined method
Full-matrix least-squares on F2
1.003
Goodness of fit (GOF) on F2
0.903
1.033
R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0268, wR2 = 0.0422
R1 = 0.0450, wR2 = 0.0437
R1 = 0.0248, wR2 = 0.0678
R1 = 0.0346, wR2 = 0.0708
R1 = 0.0188, wR2 = 0.0469
R1 = 0.0202, wR2 = 0.0476
Ar H), 7.72 (m, 1H, Ar H), 7.66 (d, 1H, JH–H = 12 Hz, NH–), 7.60–7.37
so)2](2) and [(P–N)RuCl2(PPh3)] (3) in moderate to high yields
(Scheme 1). The structures of these complexes are supported by
elemental analysis, IR spectroscopy and NMR data (Table 2), and
in the case of 1 a single crystal structural determination.
(m, 10H, Ar H), 7.27 (t, 1H, JH–H = 10 Hz, Ar H), 6.23 (d, 1H, JH–H
=
12 Hz, NH–), 3.27 (s, 3H, dmso), 2.99 (s, 3H, dmso). 31P NMR
(161 MHz, dmso-d6) d: 50.8. 13C NMR (100 MHz, dmso-d6) d:
196.3 (d, JC–P = 13.0 Hz, CO), 151.6 (d, JC–P = 18.0 Hz, C–NH2),
135.1 (d, JC–P = 9.0 Hz), 134.9 (d, JC–P = 54.0 Hz), 133.8, 132.7,
132.32 (d, JC–P = 10.0 Hz), 131.4, 131.3, 131.2 (d, JC–P = 21.0 Hz),
The 1H resonances of the –NH2 group in complex 1 appears as
two sets of signals at d 8.11 and 6.70 ppm (JH–H = 12 Hz), which
are deshielded in relation to the free ligands (Table 2). The obser-
vation of two resonances for the amine protons is in agreement
with the observed structure (C1 symmetry). The 31P NMR spectrum
shows only one singlet shift at 53.9 ppm, which is deshielded rel-
130.8 (d, JC–P = 23.0 Hz), 129.3 (d, JC–P = 11.0 Hz), 128.5 (d, JC–P
=
10.0 Hz), 128.4 (d, JC–P = 11.0 Hz), 127.6 (d, JC–P = 6.0 Hz), 47.7
(dmso), 45.3 (dmso). Anal. Calc. for C21H22Cl2NO2PRuS: C, 45.41;
H, 3.99; N, 2.52. Found: 45.01; H, 3.91; N, 2.29.
ative to the free ligand with
a coordination shift of about
70 ppm. The IR spectrum of complex 1 shows carbonyl stretching
bands at 2058 and 1996 cmꢁ1, a characteristic absorption pattern
for a dicarbonyl ruthenium species. The structure of 1 is further
confirmed by an X-ray crystallographic analysis.
Crystals of 1ꢂ(dmso)4 were grown by recrystallization in a
CH2Cl2/dmso solution at room temperature. The ORTEP plot of
1 is shown in Fig. 1 and selected bond distances and bond angles
are collected in Table 3. The structure of 1 reveals a distorted
octahedral geometry at the metal center with a bidentate coor-
dination of the P–N ligand. The two carbonyl ligands are ar-
ranged in a cis fashion and are seated trans to the nitrogen
2.2.8. Kinetic study
The rates were determined by 1H NMR measurements on sam-
ples of complex 2 and with an excess of dmso-d6 in CDCl3 or com-
plex 4 and an excess of CD3CN in CDCl3. The tube was then capped
with a septum and warmed to a certain temperature. The methyl
signals of dmso between 2.7 and 3.3 were used to calculate the
amount of the remaining starting material. Kinetic plots are shown
in Figs. S1–S6 (see Supporting information).
2.3. X-ray crystallographic analysis
atom and chloride. The Ru(1)–Cl(2) bond length, which is trans
0
to the phosphine, appears to be slightly longer (by ca. 0.03 ÅA)
than that of Ru(1)–Cl(1). The P(1)–Ru(1)–N(1) angle [82.16(5)°]
within the coordinated o-(diphenylphosphino)aniline in 1 does
not correspond exactly to 90°, which is typical for a rigid five-
member chelating ring linked through an o-phenylene backbone
[36].
Crystals suitable for X-ray determination were obtained for
1ꢂ(dmso)4, 4ꢂ(CH3CN) and 7 by recrystallization at room tempera-
ture. Cell parameters were determined using a Siemens SMART
CCD diffractometer. Crystal data of these complexes are listed in
Table 1. Complex 1 contains 4 molecules of dmso as solvent,
whereas complex 4 contains one molecule of acetonitrile. The
structures were solved using the SHELXS-97 program [34] and re-
fined using the SHELXL-97 program [35] by full-matrix least-squares
on F2 values.
The 1H NMR shifts of the –NH2 group of 2 also appear as two
signals at d 6.35 and 5.64 ppm (Table 2) with a geminal coupling
constant of 12 Hz, indicating the inequivalence of the two axial li-
gands on the metal center of 2 (one dmso and one chloride ligand).
In addition, the dmso methyl resonances appear as four singlets
between 2.1 and 3.5, a pattern typical for dmso coordinated to
ruthenium in cis-fashion [37]. These observations are in agreement
with the proposed structure of 2.
3. Results and discussion
3.1. Coordination of P–N toward Ru(II)
Due to the fluxional nature of 3, similar to that of [Cl2Ru(PPh3)3]
[39], the basis of characterizing this complex was mass spectro-
scopic analysis and elemental analysis. The ESI-MS spectrum of 3
in CH3CN matrix confirms formation of the desired complex 3 with
a peak at m/z = 717.09 [3-Cl+CH3CN]. In addition, the crystal struc-
In an attempt to prepare a series of ruthenium complexes, ami-
no-phosphine P–N was treated with a stoichiometric quantity of
[RuCl2(CO)3(THF)], [RuCl2(dmso)4] and [RuCl2(PPh3)3] to yield the
corresponding complexes [(P–N)RuCl2(CO)2] (1), [(P–N)RuCl2(dm-

26
C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
RuCl2(CO)3(THF)
(P—N)RuCl2(CO)2
THF, Δ
1
MeCN
Δ
RuCl2(DMSO)4
P—N
(P—N)RuCl2(DMSO)2
(P—N)RuCl2(MeCN)(DMSO)
THF, Δ
2
4
RuCl2(PPh3)3
CH2Cl2
(P—N)RuCl2(PPh3)
3
Scheme 1. Preparation of the ruthenium complexes.
Table 2
Selected spectral data for the Ru(II) complexes.a
Complexs
1H NMR
31P NMR
13C NMR, dC@O
mC
@
(cmꢁ1
)
c
O
d (–NH2)
d (Me– of dmso)
1b
2
4
5
6
8.11, 6.70
6.35, 5.64
5.93, 4.71
4.40, 2.78
9.68 5.51
6.15
–
53.9.
54.3
63.0
195.8 (JP–C = 12), 191.4 (JP–C = 11)
2058, 1996
–
–
1959
2045
1996
1994
3.47, 3.39 3.01, 2.17
3.35, 2.99
–
3.33, 2.91
3.07
34.9, 21.9 (JP–P = 355)
199.8 (JP–C = 14)
191.4 (JP–C = 111)
194.8 (JP–C = 118)
196.3 (JP–C = 13)
36.5
32.5
50.8
7
8b
7.66, 6.23
3.27, 2.99
a
b
c
NMR data in CDCl3, J in Hz.
NMR data in dmso-d6.
KBr, cmꢁ1
.
(a)
(b)
R
N
R
Cl
Cl
N
C(8)
Ru
C(9)
Ru
Cl
PPh
Cl
3
P
P
C(3)
N(1)
Ph
Ph
PPh
3
Ph
Ph
Ia
O(1)
C(1)
C(15)
P(1)
Ib
H
H
Ru(1)
H
H
Cl
Cl
N
N
Ru
Ru
Cl
C(2)
O(2)
PPh
Cl(2)
3
P
P
Cl(1)
PPh
Cl
3
Ph
Ph
Ph
3b
Ph
3a
Fig. 1. ORTEP plot of 1 (thermal ellipsoids at 30% probability).
Chart 2. Isomeric forms of [(P–N)RuCl2(PPh3)].
Table 3
Selected bond lengths (Å) and angles (°) for 1.
3.2. Ligand substitutions of the ruthenium complexes
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–N(1)
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
O(1)–C(1)
O(2)–C(2)
N(1)–C(3)
1.864(2)
1.885(2)
2.147(2)
2.2913(5)
2.4144(5)
2.4420(5)
1.144(2)
1.139(2)
1.455(2)
N(1)–Ru(1)–P(1)
C(1)–Ru(1)–C(2)
C(1)–Ru(1)–N(1)
C(2)–Ru(1)–N(1)
C(2)–Ru(1)–P(1)
P(1)–Ru(1)–Cl(2)
N(1)–Ru(1)–Cl(1)
C(2)–Ru(1)–Cl(2)
Cl(1)–Ru(1)–Cl(2)
82.16(5)
90.39(8)
95.84(8)
173.56(8)
96.04(6)
167.01(2)
85.17(5)
96.95(6)
88.67(2)
Scheme 2 summarizes the substitution reactions of ruthenium
complexes 1ꢃ3 with dmso, CO and triphenylphosphine. Heating
complex 2 in a mixture of THF and acetonitrile under refluxing
conditions for 6 h yielded [(P–N)RuCl2(dmso)(CH3CN)] 4 exclu-
sively. No further substitution took place even after prolonged
heating, i.e., the formation of the di-substitution product [(P–N)
RuCl2(CH3CN)2] was not observed. The 1H NMR spectrum of 4 is
similar to that of 2 except for the shift due to the methyl group
of acetonitrile. The protons of the –NH2 group within the ligand
were magnetically inequivalent with a geminal coupling constant
of 14 Hz. The resonances of the two methyl groups of dmso exhib-
ited two sets of signals, indicating the unsymmetric arrangement
of the axial ligands in the complex (see the crystal structure). It
is worth mentioning that complex 4 may be reverted back to 2
upon dissolving it in dmso, as shown in Scheme 2.
ture of [(P–NMe2)RuCl2{P(tol)3}] has been reported [24]. Thus,
complex 3 is believed to have a similar structure to [(P–NMe2)
RuCl2{P(tol)3}] (I). Gimeno and coworkers suggested that complex
I exists in two isomeric forms (Chart 2a) as evidenced by the infra-
red absorption of Ru–Cl at 320 cmꢁ1 (Ia), and at 292 and 245 cmꢁ1
(Ib) [38]. The absorptions of 3 in the far-infrared region appear at
345, 294, and 261 cmꢁ1, quite similar to those for I, indicating that
complex 3 might be in two isomeric forms 3a and 3b.
The solid-state structure of 4ꢂ(CH3CN) was determined using X-
ray crystallography and an ORTEP view of the molecule is shown in

C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
27
Ph
Ph
ACN
Ru
Ph
Ph
dmso
Ru
Ph CO
Ph
P
Ph
Ph
P
dmso
PPh3
P
dmso
Cl
dmso
Cl
C
P
O
H
2N
Cl
Cl
Ru
Cl
Ru
A
CN
CDCl3, r.t.
DMSO
H2N
Cl
PPh3
PPh3
H2N
H2N
Cl
Cl
4
2
3
5
Ph
Ph
CO (150 psi)
P
P—N
NH2
ACN = CH3CN
+
Ph
NCCH3
Ph
CO
Ph
Cl
Ph
P
Ph
Ph
CO
Ph
Ph
120 oC
dms
P
dmso
dmso
CO
CO
dmso
60 oC
P
P
Cl-
dmso
Cl
Ru
Cl
Ru
Cl
Ru
Cl
Ru
Cl
o
DCM, r.t.
H2N
CO
H2N
H2N
H2N
Cl
1
7
6
8
Scheme 2. Ligand substitutions among the various ruthenium complexes.
via the direct substitution of [RuCl2(dmso)4] with an equal molar
amount of P–N. On the other hand, treatment of 2 with an excess
of PPh3 in refluxing THF produced 3 slowly, i.e., complexes 2 and 3
turned out to be inter-convertible. Under an atmospheric pressure
of CO, complex 3 was readily transferred to form a hexa-coordi-
nated ruthenium species, 5.
C(7)
C(13)
C(8)
Substitutions of 2, 3 and 4 with carbon monoxide appear to
make for an interesting exploration. Treatment of 4 with CO in
dichloromethane at room temperature under higher pressure con-
ditions (150 psi) yielded an ionic species, 6, which then slowly
underwent substitution to form the neutral ruthenium complex
7. However, the direct formation of 7 from 4 is possible via carrying
out the substitution under atmospheric CO. Heating complex 7 in a
dmso solution at 120 °C resulted in the formation of 8, a stereoiso-
mer of 7. In addition, there are three more routes leading to com-
plex 8: (i) treatment of 2 with CO (150 psi) in dmso, (ii) heating 1 in
dmso at 120 °C, and (iii) substitution of 5 with dmso (Scheme 2).
Nevertheless, complex 8 did not isomerize back to either 7 or 6 un-
der mild conditions, indicating that complex 8 is a thermodynamic
product.
P(1)
O(1)
C(20)
C(22)
C(21)
N(2)
C(1)
Ru(1)
N(1)
Cl(1)
C(19)
Cl(2)
Fig. 2. ORTEP plot of 4 (thermal ellipsoids at 30% probability).
Table 4
Selected bond distances (Å) and bond angles (°) of 4.
Ru(1)–N(1)
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
Ru(1)–N(2)
Ru(1)–S(1)
C(21)–N(2)
2.1336(17)
2.2404(5)
2.4103(5)
2.4545(5)
2.0035(17)
2.2356(5)
1.130(3)
N(1)–Ru(1)–P(1)
N(2)–Ru(1)–P(1)
Cl(1)–Ru(1)–Cl(2)
Cl(2)–Ru(1)–N(2)
N(2)–Ru(1)–N(1)
Cl(1)–Ru(1)–P(1)
Cl(2)–Ru(1)–P(1)
83.37(5)
89.86(5)
87.773(19)
87.08(5)
90.02(7)
3.3. Characterization of the ruthenium carbonyl complexes
The structures of this series of carbonyl-substituted complexes
were determined by both spectroscopic and elemental analyses. In
addition, the structure of complex 7 was confirmed by X-ray crys-
tal structural analyses. The characteristic stretching frequencies of
the carbonyls are listed in Table 2. All carbonyls in this series of
Ru(II) complexes are in a terminal coordination mode. As for the
geometric relationship between CO and phosphines, 13C NMR
shifts of the carbonyl carbons, along with C–P coupling constants
(JP–C), offer valuable information regarding the stereochemistry of
the complexes.
94.261(19)
170.992(19)
Fig. 2, together with the atomic numbering system; selected bond
lengths and angles are given in Table 4. The structure discloses a
slightly distorted octahedral geometry at the metal center with a
bidentate coordination of the P–N ligand. The two chloride ligands
are seated in a cis fashion, whereas the coordinating dmso ligand is
trans to the amine donor. The dmso ligand in 4 is S-bonded, not O-
bonded. This stereo-arrangement around the ruthenium center is
consistent with the spectroscopic analysis. The P(1)–Ru(1)–N(1)
angle [83.37(5)°] is not 90°, showing a small bite angle attributable
to the P–N ligand.
The 31P NMR spectrum of complex 5 displays two sets of dou-
blets with JP–P = 355 Hz. This large coupling constant clearly indi-
cates that the two phosphorus donors are seated in a trans
position around the ruthenium ion. Importantly, the observation
of a triplet splitting pattern (JP–C = 13.5 Hz) for the carbonyl-carbon
in the 13C NMR spectrum provides convincing evidence for the
coordination of CO being cis toward the two phosphines. The
inequivalence of the resonances due to –NH2 in the 1H NMR spec-
trum indicates that they are diastereotopic protons. This observa-
Transformation of 3 occurred by the addition of the coordinat-
ing solvent dmso, yielding the adduct 2, which is identical to that

28
C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
(a)
Cl(2)
axial dmso
O(1)
equatorial dmso
free dmso
C(21)
C(13)
N(1)
P(1)
C(1)
Ru(1)
C(20)
S(1)
O(2)
C(6)
(b)
C(19)
C(7)
Cl(1)
Fig. 4. 1H NMR shifts of dmso signals of 2 in the presence of dmso-d6 in CDCl3 at
50 °C (a) t = 0, (b) t = 145 min.
Fig. 3. OPTEP view of
2.148(1) Å; Ru(1)–P(1) 2.4048(4) Å; Ru(1)–S(1) 2.2473(4) Å; N(1)–Ru(1)–P(1)
79.86(3).
7 (thermal ellipsoids at 30% probability). Ru(1)–N(1)
tion clearly reveals that the axial positions are occupied by two dif-
ferent ligands, i.e., carbonyl and chloride. Thus the stereochemistry
around the metal center for 5 can be unambiguously established
according to these spectroscopic observations.
Table 5
Kinetic data from dmso exchanging on 2.a
T (K)
kobs (sꢁ1
)
k (sꢁ1
)
lnk
ln(k/T)
D
G– (kcal/mol)
294
323
333
4.91Eꢁ06
1.36Eꢁ04
3.92Eꢁ04
1.96Eꢁ05
5.44Eꢁ04
1.57Eꢁ03
ꢁ10.84
ꢁ7.56
ꢁ6.46
ꢁ16.52
ꢁ13.29
ꢁ12.27
23.54
23.79
23.85
Complexes 7 and 8 have an identical formulation of [(P–
N)Ru(dmso)(CO)Cl2], which is determined by spectroscopic meth-
ods, and the structure of 7 is further confirmed by X-ray diffraction
analysis. The 1H NMR spectrum of 7 shows one set of signals for –
NH2 with an integration of two protons, illustrating that both the
two axial ligands are identical, i.e., two chlorides in trans axial posi-
tions. The large 31P–13C coupling constant (JC–P = 118 Hz) is due to
the carbonyl carbon resonance trans to phosphine. The molecular
structure of compound 7, determined by X-ray crystallography, is
distorted octahedral with trans chlorides and the dmso trans to
the –NH2 (Fig. 3). The dmso molecule, which is S-bonded to the
metal, is located at the equatorial plane and arranged trans to the
amine donor. The Ru(1)–P(1) [2.4048(4) Å] and Ru(1)–N(1)
[2.148(1) Å] bond distances are in the normal range. Since both 7
and 8 have the same composition, the stereochemistry of 8 is thus
assigned on the basis of spectroscopic analysis. The arrangement
between the chloride and carbonyl donors in a trans fashion on
complex 8 is evidenced by the observation of two set resonances
for –NH2 and two methyl resonances of dmso in the 1H NMR
spectrum.
a
[2] = 4.1 mM in CDCl3, dmso-d6 (0.1 mmol).
Table 6
Kinetic data from CD3CN exchanging on 4.a
T (K)
kobs (sꢁ1
)
k (sꢁ1
)
lnk
ln(k/T)
D
G– (kcal/mol)
313
323
328
333
9.29Eꢁ06
4.24Eꢁ05
1.22Eꢁ04
2.21Eꢁ04
1.41Eꢁ05
6.42Eꢁ05
1.85Eꢁ04
3.35Eꢁ04
ꢁ11.17
ꢁ9.65
ꢁ8.60
ꢁ8.00
ꢁ16.92
ꢁ15.43
ꢁ14.39
ꢁ13.81
25.31
25.17
24.88
24.87
a
[4] = 4.4 mM in CDCl3, CD3CN (0.26 mmol).
D
S– are determined to be 88.6 0.8 kJ/mol and ꢁ33 2 J/mol K,
respectively.
Complex 6 has an ionic form, as evidenced by its conductivity
measurement (86.1 ohmꢁ1 cm2 molꢁ1) and its structure is also
established by NMR spectroscopy. The 13C spectrum of 6 showed
a carbonyl shift at d 191.4 with JC–P = 111 Hz. The larger JC–P, similar
to that of 7, is believed to have arisen from the carbonyl ligand
trans to the phosphine donor in 6. Meanwhile, the shift at d 1.83
in the 1H NMR spectrum was assigned to the methyl group of
the coordinated acetonitrile. Other spectral data are similar to
those of 4, allowing us to establish the coordination environment
around the metal center.
CD3
O
Ph
S
dmso(ax)
Ph
Ph
P
Ph
CD3
dmso(eq)
P
dmso-d6
dmso(eq)
Cl
Ru
Ru
Cl
N
N
H2 Cl
H2 Cl
2'
2
ð1Þ
In the case of the acetonitrile complex 4, degenerate exchange
with free acetonitrile is also slow, so that when complex 4 is in
the presence of free acetonitrile, no line broadening of the signal
for bound acetonitrile at 1.67 ppm is observed, even for tempera-
tures up to 60 °C. It should be noticed that the bound dmso did
not undergo substitution in the presence of excess acetonitrile.
The rate of CH3CN exchange was studied via 1H NMR-spectroscopy
by monitoring a solution of 4 with an excess of CD3CN in CDCl3.
The integration of methyl shifts corresponding to the free and
bound acetonitriles was recorded. The kinetics followed pseudo
first order rate behaviors, similar to complex 2. The data are illus-
3.4. Kinetic study
We have examined the rate of dmso self-exchange in complex 2
using 1H NMR spectroscopy (Eq. (1)). The degenerate exchange
with free dmso-d6 was slow enough that the free dmso and the
bound dmso could be observed (Fig. 4). The rate of ligand exchange
was thus monitored by treatment of 2 with excess dmso-d6 in
CDCl3 at 21, 50 and 60 °C, and by measuring the decrease in the
integration of bound dmso in 2. The change in integration is pro-
portional to the concentration of 2, and pseudo first order rate con-
stants were calculated for complex 2. The data are summarized in
Table 5. The free energy of activation for the exchange reaction is
trated in Table 6. Similarly,
obtained from the Eyring plots are 137 8 kJ/mol and 101 24 J
/mol K, respectively.
D D
H– and S– of the substitution
estimated to be 23.7 kcal/mol. From the Eyring plots,
D
H– and

C.-C. Lee et al. / Polyhedron 35 (2012) 23–30
29
3.5. Discussion
[(P–N)RuCl2(dmso)2] and [(P–N)RuCl2(PPh3)] were prepared by
reaction of P–N with [RuCl2(CO)3(THF)], [RuCl2(dmso)4] and
[RuCl2(PPh3)3], respectively. Further ligand substitution reactions
of these species with acetonitrile, dmso and carbon monoxide were
investigated (Scheme 2). The stereochemistry of these complexes
was unambiguously determined by spectroscopic methods and
through X-ray single crystal analysis of 1, 4 and 7. Kinetic studies
of self ligand exchanges relative to complexes 2 and 4 show the
small difference in dissociation of dmso or acetonitrile from the
Ru(II) center. This study provides some insight into ligand effects
on Ru(II) complexes. Studies on the catalytic reactivity of these
complexes are ongoing in our laboratory and some of the results
show that complex 1 is an excellent catalyst for the preparation
of amines from nitroarenes with alcohols [41].
We have successfully prepared a series of Ru(II) complexes con-
taining a P–N ligand and have established the stereochemistry of
these Ru(II) species. The stereochemistry of [(P–N)RuLL0Cl2] has
been established by spectroscopic and X-ray crystal structural
analyses. Changes in the metal precursor or ligand substituents
can lead to the preferential formation of particular isomers
(Scheme 2). The ligand substitution described in this work will
help us understand the ligand effects on Ru complexes and related
compounds.
Complex 3 readily reacts with dmso at an ambient temperature
to yield 2, but the conversion of 2 back to 3 requires harsh condi-
tions with an excess of phosphine. This might be due to the steric
bulkiness of triphenylphosphine versus dmso and the
donation from d
of the Ru(II) ion to pp⁄ of the S@O bond [40]. Ow-
ing to the strong -acid nature of CO ligands, the carbonyls in 1 did
p-back-
p
p
Acknowledgment
not undergo substitution with dmso under ambient conditions, but
the replacement took place at a higher temperature (120 °C) to
produce 8.
We thank the National Science Council, Taiwan, ROC for finan-
cial support (NSC97-2113-M-002-013-MY3).
The 1H NMR resonances of the S-bonded dmso in complex 2 ap-
peared as four singlets between d 3.5 and 2.1, a pattern typical for
diastereotopic methyl groups of dmso coordinated to ruthe-
nium(II). Through a ligand exchanging study and crystal structural
analysis of 4, we were able to identify the 1H shifts of the methyl
groups for the equatorial and axial dmso ligands (Eq. (1)). The
investigation of dmso self-exchange revealed that the axial dmso
is much more easily replaced by the incoming ligand than the
equatorial one (Eq. (2)).
Appendix A. Supplementary data
CCDC 804084, 804085 and 804086 contains the supplementary
crystallographic data for 1, 7 and 4, respectively. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-
336-033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.poly.2011.12.032.
ACN
Ph
P
dmso
Ph
Ph
P
Ph
+ ACN
dmso
Cl
dmso
Cl
Ru
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ð2Þ
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N
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30
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