Coordination and catalytic activity of ruthenium complexes containing tridentate P,N,O ligands

Article abstract of DOI:10.1002/ejic.201100647

The coordination chemistry of Ru^II ions with [2-(diphenylphosphanyl)-N-(o-hydroxybenzylidene)]aniline (PNO-H) and the methylated analogue PNO-Me have been studied. Thus, [(PNO)RuCl(dmso) ₂] (1), [(PNO)₂Ru] (2), [(PNO)RuCl(PPh₃)] (3) and [(PNO)RuCl(CO)₂] (4) were synthesized by reactions of various Ru^II precursors with PNO-H. Treatment of PNO-Me with [RuCl ₂(dmso)₄] resulted in in the formation of [P,N-(PNO-Me)Ru(dmso)₂Cl₂] (5). However, complexation of PNO-Me with [RuCl₂(CO)₃(THF)] (THF = tetrahydrofuran) provided a mixture of [P,N-(PNO-Me)Ru(CO)₂Cl₂] (6) and 4 because O-demethylation took place during the reaction. All of the Ru ^II complexes have been characterized by elemental analysis and spectroscopic techniques, as well as X-ray crystal structural analysis for 2, 4 and 6. The ruthenium complexes investigated in this work, except 2, are good precatalysts for the reductive amination of amine with alcohols, and 4 appears to be the best. Moreover, 4 can catalyze the direct amination of nitrobenzene with benzyl alcohol to the corresponding secondary amine. Ruthenium complexes containing P,N,O ligands have been synthesized and characterized. These Ru ^II species appear to be good catalysts for the reductive amination of amines or nitrobenzene with alcohols.

Full text of DOI:10.1002/ejic.201100647

FULL PAPER
DOI: 10.1002/ejic.201100647
Coordination and Catalytic Activity of Ruthenium Complexes Containing
Tridentate P,N,O Ligands
Chun-Chin Lee,[a] Wan-Yi Chu,[a] Yi-Hong Liu,[a] Shie-Ming Peng,[a] and
Shiuh-Tzung Liu*[a]
Keywords: Ruthenium / Tridentate ligands / Amination / Hydrogen transfer / N,P ligands
The coordination chemistry of RuII ions with [2-(diphenyl-
phosphanyl)-N-(o-hydroxybenzylidene)]aniline
(PNO-H) of the RuII complexes have been characterized by elemental
because O-demethylation took place during the reaction. All
and the methylated analogue PNO-Me have been studied.
Thus, [(PNO)RuCl(dmso)2] (1), [(PNO)2Ru] (2), [(PNO)RuCl-
(PPh3)] (3) and [(PNO)RuCl(CO)2] (4) were synthesized by re-
actions of various RuII precursors with PNO-H. Treatment of
PNO-Me with [RuCl2(dmso)4] resulted in in the formation of
[P,N-(PNO-Me)Ru(dmso)2Cl2] (5). However, complexation of
PNO-Me with [RuCl2(CO)3(THF)] (THF = tetrahydrofuran)
provided a mixture of [P,N-(PNO-Me)Ru(CO)2Cl2] (6) and 4
analysis and spectroscopic techniques, as well as X-ray crys-
tal structural analysis for 2, 4 and 6. The ruthenium com-
plexes investigated in this work, except 2, are good precata-
lysts for the reductive amination of amine with alcohols, and
4 appears to be the best. Moreover, 4 can catalyze the direct
amination of nitrobenzene with benzyl alcohol to the corre-
sponding secondary amine.
PNO-Me2 towards [(COD)PdMeCl].[1] The substituent on
the oxygen atom influences its coordination nature. The
oxygen donor in PNO-Me2 appears to be quite labile as
demonstrated in Equation (1), whereas PNO-H can lose the
phenolic proton and act as a stable chelator in A. Such a
difference in coordination makes B catalytically active in
the oligomerization of ethylene, whereas A is inactive.
Ruthenium is known to be catalytically active for various
organic transformations. Thus, the modification of ligands
to fine tune the activity of ruthenium ions has received
much attention. In this context, several RuII complexes con-
taining P,N,O tridentate ligands have been reported.[2–4]
The aim of this paper is to describe the complexation of
PNO-H and PNO-Me towards RuII ions and the catalytic
activity of the resulting complexes in hydrogen transfer re-
duction for the preparation of amines.
Introduction
As part of our ongoing research on the coordinating
capability of tridentate ligands containing phosphorus, ni-
trogen and oxygen donors towards transition metal ions, we
have described the coordination chemistry of PNO-H and
Results and Discussion
Synthesis and Characterization of Ruthenium(II) Complexes
PNO-H and PNO-Me were prepared according to re-
ported methods.[1] A series of ruthenium(II) complexes con-
taining PNO-H were synthesized as depicted in Scheme 1.
In the presence of excess of triethylamine, reaction of PNO-
H with [RuCl2(dmso)4] (dmso = CH3SOCH3), in a 1:1 ratio,
afforded a mixture of 1 and 2. Complex 1 was characterized
spectroscopically, and the data were found to be identical
to those reported.[3] Complex 2 was purified by column
chromatography and obtained as a purple-red crystalline
solid. The 31P NMR spectra of 1 and 2 in CDCl3 show only
[a] Department of Chemistry, National Taiwan University 1,
Sec. 4, Roosevelt Road, Taipei, Taiwan
Fax: +886-2-23636359
E-mail: stliu@ntu.edu.tw
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one resonance signal, which appears at 55.9 and 64.1 ppm,
Characterization of carbonyl-substituted 4 was achieved
respectively. The 31P resonance signals for 1 and 2 are by spectroscopic and elemental analyses. Carbonyl stretch-
shifted downfield compared to the free ligand, which is typ- ing frequencies appear at 2053 and 2000 cm–1 in the IR
ical for the coordination of phosphane ligands.
spectrum of 4, which are characteristic for a [L3RuCl-
(CO)2] species. Carbon–phosphorus coupling constants ob-
tained from the NMR spectra (JPC = 12 Hz), suggest that
the carbonyl ligands are cis to the phosphane donor of the
complexes. The cis arrangement of the two carbonyl donors
in 4 is evidenced by two sets of carbonyl resonances (193.9
and 191.3 ppm) in the 13C NMR spectrum. The formula-
tion is further confirmed by single-crystal X-ray crystallo-
graphic analysis. Crystals were grown by slow evaporation
of a CH2Cl2/THF solution of 4 at room temperature. The
ORTEP plot of 4 is shown in Figure 2, and selected bond
lengths and angles are collected in Table 1. The ruthenium
atom is hexacoordinate in an octahedral geometry, analo-
gous to 2. The coordination geometry is completed by the
PNO chelate ligand, two carbonyl groups and a chloride
ion, and the stereochemistry around the metal centre is con-
sistent with the spectroscopic analysis. The P(1)–Ru(1)–
N(1) angle [83.36(11)°] is not 90°, showing a small bite an-
gle attributable to the o-phenylene linkage of the phosphane
and imine donors. The Ru–N and Ru–O bond lengths are
slightly shorter in 4 than 2, which may be associated with
the change of coordinating ligands around the metal centre.
Scheme 1. Preparation of 1–4.
The structure of 2 was confirmed by single-crystal X-
ray diffraction analysis, and the ORTEP plot is shown in
Figure 1. The two PNO ligands around the metal centre in
2 are arranged in a mer–mer configuration with the two
nitrogen atoms trans to one another and the two phospho-
rus and two oxygen atoms in a cis configuration. This coor-
dination mode is similar to that of other ruthenium(II)–
PNO complexes with similar ligands.[3,4a,4b] The average
Ru–P, Ru–O and Ru–N bond lengths in 2 are 2.23, 2.10 and
2.07 Å, respectively, which compare well to those observed
in related RuII complexes.
Figure 2. ORTEP plot of 4 (drawn with 30% probability ellipsoids).
Table 1. Selected bond lengths [Å] and angles [°] for 4.
Bond lengths
Bond angles
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–N(1)
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–O(3)
O(1)–C(1)
O(2)–C(2)
O(3)–C(3)
1.886(4)
1.880(4)
2.109(3)
2.297 (1)
2.4175(9)
2.091(3)
1.137(5)
1.121(4)
1.289(5)
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(1) 94.72(3)
C(2)–Ru(1)–Cl(1) 173.36(16)
83.36(11)
91.31(17)
175.12(15)
92.57(13)
91.28(15)
Figure 1. ORTEP plot of 2 (drawn with 30% probability ellipsoids).
Selected bond lengths [Å] and angles [°]: Ru(1)–N(1) 2.081(3),
Ru(1)–N(2) 2.067(3), Ru(1)–O(1) 2.102(2), Ru(1)–O(2) 2.101(3),
Ru(1)–P(1) 2.2323(9), Ru(1)–P(2) 2.238(1), N(2)–Ru(1)–N(1)
177.5(1), P(1)–Ru(1)–P(2) 96.97(4), O(2)–Ru(1)–O(1) 83.7(1).
O(3)–Ru(1)–P(1)
Ru(1)–N(1)–C(9)
174.17(8)
122.1(2)
Treatment of PNO-H with equimolar amounts of
Similarly, PNO-Me reacted with [RuCl2(dmso)4] in THF
[RuCl2(PPh3)3] and [RuCl2(CO)3(THF)] yielded the substi- with heating, affording the substitution product
5
tution products 3 and 4, respectively (Scheme 1). Complex (Scheme 2). Based on NMR and MS data (Table 2), the co-
3 was characterized by mass spectrometry and elemental ordination environment around ruthenium centre in 5 is
analysis. The ESI-MS confirms the formation of 3 with a proposed to be similar to that of the previously reported
peak at m/z = 785.1432 [M – Cl + CH3CN]+. The fluxional complex [(bidentate)Ru(dmso)2Cl2], i.e. PNO-Me acts as a
nature of 3 is similar to that of complexes with the chemical bidentate ligand. The dmso methyl resonances appear as
formula [(R3P)3RuCl2].[5]
four singlets between 2.85 and 3.69 ppm, a pattern typical
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Ruthenium Complexes with P,N,O Ligands
for dmso coordinated to ruthenium in a cis fashion.[6]
HRMS (ESI) of 5 shows a peak at m/z = 729.0730, which
corresponds to [M – Cl + CH3CN]+.
Figure 3. ORTEP plot of 6 (drawn with 30% probability ellipsoids).
Catalysis
Scheme 2. Complexation of RuII ions with PNO-Me.
Table 2. Selected bond lengths [Å] and angles [°] for 6.
It was of interest to test the catalytic activity of 1–6. We
have recently shown that phosphane–amine complexes of
ruthenium(II) are excellent precatalysts for N-alkylation of
amines with alcohols, which involves a series of tandem re-
actions: oxidation of alcohols, condensation of amines with
carbonyl compounds and reduction of imines (Scheme 4).[7]
Such a synthetic methodology is of interest for its relevance
to atom-economical synthesis.[8–10] We investigated the ac-
tivity of 1–6 as catalysts for the N-alkylation of amines with
alcohols.
Bond lengths
Bond angles
Ru(1)–C(1) 1.88(2)
Ru(1)–C(2) 1.79(17)
Ru(1)–N(1) 2.164(18)
N(1)–Ru(1)–P(1)
C(1)–Ru(1)–C(2)
C(1)–Ru(1)–N(1)
C(2)–Ru(1)–N(1)
P(1)–Ru(1)–Cl(1)
79.2(5)
90(4)
175.9(8)
90(4)
Ru(1)–P(1)
2.308(5)
Ru(1)–Cl(1) 2.425(5)
Ru(1)–Cl(2) 2.41(4)
171.0(2)
Cl(2)–Ru(1)–Cl(1) 86.4(7)
The reaction of PNO-Me with an equimolar amount of
[RuCl2(CO)3(THF)] in THF with heating, led to the pre-
cipitation of 4 and 6 (Scheme 2). Apparently, the formation
of 4 occurs through the cleavage of the ligand C–O bond.
Scheme 3 illustrates the possible pathway of this demethyl-
ation. It is believed that 6 undergoes chloride substitution
by the ether donor around the metal centre, which yields
7. The free chloride acts as a nucleophile and undergoes
nucleophilic attack at the methyl carbon atom, providing
the C–O cleavage product. However, carrying out the same
reaction in the presence of triethylamine yielded 6 exclu-
sively.
Scheme 4. Reaction pathway of N-alkylation with alcohols.
We initially explored the reaction of aniline with benzyl
alcohol as a model system [Equation (2)]. In a typical ex-
periment, a mixture of aniline, benzyl alcohol, KOtBu and
RuII complex (1:3:0.4:0.01) was placed in a flask. Excess
benzyl alcohol was used as the solvent, and the mixture was
heated to 110 °C. The desired amine and/or imine products
Scheme 3. Pathway for the demethylation of 6.
were extracted from the reaction mixture and analyzed by
1
The structure of 6 is supported by elemental analysis and GC and H NMR spectroscopy. The results are summa-
IR and NMR spectroscopic data. The 31P NMR spectrum rized in Table 3. Catalyst screening in the model reaction
of 6 shows a single resonance at 50.7 ppm, which is shifted revealed that all the ruthenium(II) complexes triggered the
by ca. 10 ppm compared to that of 5. The crystal structure reaction, except 2. Owing to the bischelation of the PNO
of 6·1/2(Et2O) confirms its formulation. The ORTEP plot ligands around the metal centre in 2, the lack of a vacant
of 6 is shown in Figure 3, and the relevant geometric pa- coordination site hinders its catalytic activity. All the other
rameters are collected in Table 2. The structure has a complexes show good catalytic activities in this reaction,
slightly distorted octahedral geometry at the metal centre although significant differences in the ratio of amine vs.
with P,N-coordination of PNO-Me. The Ru(1)–N(1) and imine products are observed. Taking into account the short
Ru(1)–P(1) distances are 2.16(2) and 2.308(5) Å, respec- reaction times needed and the high percentage of amine
tively, which lie in the expected ranges.[3–4]
yielded, complex 4 lies among the most efficient catalysts
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C.-C. Lee, W.-Y. Chu, Y.-H. Liu, S.-M. Peng, S.-T. Liu
FULL PAPER
for this type of reaction (Table 3, Entry 4). In terms of turn-
Using our protocol, we were able to produce a variety of
over frequency (TOF) for this reaction, these results are amines from the corresponding alcohols (Table 4). Under
comparable to or better than previously reported rutheni- the optimized reaction conditions, various substituted
um(II) systems such as [RuCl2(PPh3)3][11] and [Ru(p- benzyl alcohols reacted with anilines to yield the corre-
cymene)Cl2]2.[12]
sponding amines in excellent yields (Entries 1–4 and 6 –
10). Other amines such as cyclohexylamine or piperidine
reacted smoothly with benzyl alcohol to give the corre-
sponding amine in good yields (Entries 11 and 12). How-
ever, the reaction of a secondary alcohol with cyclohex-
ylamine was not quite as successful (Entry 13).
It is worth mentioning that 4 can also catalyze the direct
amination of nitrobenzene with an alcohol, which is more
sustainable for the synthesis of amines.[7,10] Typically, a mix-
ture of nitrobenzene, potassium tert-butoxide, 4 and benzyl
alcohol was heated under a nitrogen atmosphere for 24 h,
and N-benzylaniline was obtained in 97% yield [Equation
(3)]. Apparently, the reduction of a nitro group can be
achieved by a hydrogen transfer reduction with 4.
Table 3. Reductive amination catalyzed by 1–6.[a]
Entry
Catalyst Time [h]
Amine[b]
Imine[b]
TOF[c]
1
2
3
4
5
6
1
2
3
4
5
6
24
24
4
3
4
92%
trace
72%
Ͼ 99%
87%
93%
3%
14%
6%
–
trace
trace
4
Ͻ 1
18
33
22
23
4
[a] Reaction conditions: benzylamine (0.3 mmol), RuII complex
(3ϫ10–3 mmol) and tBuOK (0.12 mmol) in benzyl alcohol
1
(0.9 mmol). [b] Yields based on integrations from H NMR spec-
troscopy. [c] TOF = mol(substrate)/mol(Ru complex)/h (based on
conversion to the amine).
Table 4. Results of reductive amination catalyzed by 4.
Conclusions
We have reported the synthesis and characterization of a
series of ruthenium complexes bearing PNO ligands. Typi-
cally, [(PNO)RuCl(dmso)2], [(PNO)2Ru], [(PNO)RuCl-
(PPh3)] and [(PNO)RuCl(CO)2] were synthesized by reac-
tions of various RuII precursors with deprotonated PNO-
H. Complexation of [RuCl2(CO)3(THF)] with PNO-Me in
THF with heating causes demethylation of the ligand to
yield [(PNO)RuCl(CO)2]. The structures of these complexes
were unambiguously determined by spectroscopic methods
and X-ray single crystal analysis (2, 4 and 6). Complex 4 is
catalytically active for the reductive amination of amines
with alcohols. Furthermore, the direct amination of nitro-
benzene with benzyl alcohol leading to the secondary amine
can be achieved with 4 as the catalyst. This study provides
an insight into ligand effects on RuII complexes. Studies on
the catalytic reactivity of these complexes are ongoing in
our laboratory.
Experimental Section
General: All reactions, manipulations and purifications steps were
performed under a dry nitrogen atmosphere. THF was distilled un-
der nitrogen with sodium benzophenone ketyl. Dichloromethane
and acetonitrile were dried with CaH2 and distilled under nitrogen.
Other chemicals and solvents were of analytical grade and were
used after being degassed. PNO-H and PNO-Me were prepared
according to the reported method.[1a]
[a] Reaction conditions: amine (0.3 mmol), tBuOK (0.12 mmol), 4
(3ϫ10–3 mmol) in alcohol (0.9 mmol) at 110–130 °C for 4 h. [b]
Yield based on NMR integration. [c] 10% of imine product. [d] At
150 °C. [e] 38% of imine product.
NMR spectra were recorded in CDCl3 or [D6]acetone with a
Bruker AVANCE 400 spectrometer. Chemical shifts are given in
1
ppm relative to Me4Si for H and 13C and to 85% H3PO4 for 31P
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Ruthenium Complexes with P,N,O Ligands
NMR spectroscopy. IR spectra were measured with a Nicolet
Magna-IR 550 spectrometer (Series-II).
131.0, 129.7, 129.6 (d, JCP = 2.3 Hz), 129.2, 128.4 (d, JCP = 6.3 Hz),
128.0 (d, JCP = 10.5 Hz), 127.5 (d, JCP = 10.0 Hz), 127.0 (d, JCP
=
50.0 Hz), 122.8, 122.3 (d, JCP = 8.9 Hz), 120.4, 111.8, 55.8 (OMe),
[(PNO)RuCl(dmso)2] (1) and [(PNO)2Ru] (2): A mixture of PNO-
H (104 mg, 0.27 mmol), [RuCl2(dmso)4] (131 mg, 0.27 mmol) and
triethylamine (0.5 mL) in anhydrous THF (3 mL) was heated to
reflux for 6 h. Filtration of the reaction mixture gave a dark red
solid, which was washed with water to remove ammonium salts.
Crystallization from ether yielded 1 as an orange solid (81 mg,
45%). The residue was then chromatographed on alumina oxide
with THF/CH3OH. A dark-red band was collected and concen-
trated to give 2 as a purple-red solid (58 mg, 25%). 1: 1H NMR
(400 MHz, CDCl3): δ = 8.84 (s, 1 H, HC=N), 7.90–6.85 (m, 16 H,
Ar-H), 6.87 (d, J = 8 Hz, 1 H, Ar-H), 6.51 (t, J = 8 Hz, 1 H, Ar-
H), 3.29 (s, 3 H, dmso), 3.07 (s, 3 H, dmso), 2.53 (s, 3 H, dmso),
2.48 (s, 3 H, dmso) ppm. 31P NMR (161 MHz, CDCl3): δ =
55.9 ppm (identical to reported data).[3] 2: 1H NMR (400 MHz,
CDCl3): δ = 8.93 (s, 2 H, HC=N), 7.98 (d, J = 8.0 Hz, 2 H, Ar-
H), 7.53 (t, J = 8.0 Hz, 2 H, Ar-H), 7.45 (d, J = 8.0 Hz, 2 H, Ar-
H), 7.17–6.65 (m, 13 H, Ar-H), 6.02 (br., 2 H, Ar-H) ppm. 31P{1H}
51.2 (dmso), 47.9 (dmso), 45.9 (dmso), 45.2 (dmso) ppm. HRMS
(ESI): calcd. for C32H37ClN2O3PRuS2 [M
– Cl +
MeCN]+
729.0715; found 729.0730. C30H34Cl2NO3PRuS2·H2O (759.69):
calcd. C 48.58, H 4.89, N 1.89; found C 48.90, H 4.60, N 1.91.
[P,N-(PNO-Me)Ru(CO)2Cl2] (6): A mixture of PNO-Me (105 mg,
0.26 mmol), [RuCl2(CO)3(THF)] (86 mg, 0.26 mmol) and triethyl-
amine (1 mL) in THF (3 mL) was stirred at room temperature for
10 min. During the reaction, a yellow precipitate formed, which
was collected by filtration and washed with small amount of THF
to give 6 (62 mg, 40%). IR (THF): ν = 2061, 1999 cm–1 (νC=O). 1H
˜
NMR (400 MHz, CDCl3): δ = 9.4 (s, 1 H, N=CH), 7.91 (m, 2 H,
Ar-H), 7.53–7.15 (m, 14 H, Ar-H), 6.88 (t, JHH = 7.6 Hz, 1 H Ar-
H), 6.86 (d, JHH = 7.6 Hz, 1 H Ar-H), 3.61 (s, 3 H, OCH3) ppm.
31P NMR (161 MHz, CDCl3): δ = 50.7 ppm. 13C NMR (100 MHz,
CDCl3): δ = 193.6 (d, JCP = 12.2 Hz, CO), 193.6 (d, JCP = 10.7 Hz,
CO), 172.9, 157.6, 154.9 (d, JCP = 16.7 Hz), 134.5 (d, JCP
10.7 Hz), 134.0, 132.7 (d, JCP = 57.7 Hz), 132.6, 131.92 (d, JCP
=
=
NMR (161 MHz, CDCl3):
δ = 64.1 ppm. C50H38N2O2P2Ru·
3.0 Hz), 131.68 (d, JCP = 10.6 Hz), 131.5, 131.3, 130.0, 129.2 (d,
JCP = 10.7 Hz), 129.1 (d, JCP = 73.7 Hz), 128.7 (d, JCP = 11.4 Hz),
CH3OH (825.9): calcd. C 68.52, H 4.74, N 3.13; found 68.75, H
4.46, N 2.99.
128.1 (d, JCP = 6.9 Hz), 126.8 (d, JCP = 55.5 Hz), 123.34 (d, JCP
=
[(PNO)RuCl(PPh3)] (3):
A
mixture of PNO-H (104 mg,
9.9 Hz), 121.9, 120.6, 111.8, 55.6 ppm. ESI-MS: m/z = 552.07 [M –
Cl]+. C28H22Cl2NO3PRu (623.44): calcd. C 53.94, H 3.56, N 2.25;
found C 53.59, H 3.61, N 2.01.
0.27 mmol), [RuCl2(PPh3)3] (259 mg, 0.27 mmol) and triethylamine
(0.5 mL) in THF (5 mL) was heated to reflux for 6 h. Upon re-
moval of THF, the residue was washed with diethyl ether/CH2Cl2
and reprecipitated by acetone to yield 2 as a brown solid (111 mg,
53%). HRMS (ESI): calcd. for C45H37N2OP2Ru [M – Cl +
MeCN]+ 785.1425; found 785.1432. C43H34ClNOP2Ru (779.22):
calcd. C 66.28, H 4.40, N 1.80; found C 66.75, H 4.60, N 1.99.
Catalysis: Typical procedure for N-alkylation of amine with an
alcohol.
A
mixture of amine (0.3 mmol), RuII complex
(3ϫ10–3 mmol), tBuOK (0.12 mmol) in an alcohol (0.9 mmol) was
placed in a flask under atmospheric pressure of nitrogen and heated
by an oil bath at 110–150 °C. On completion of the reaction, brine
(3 mL) and CH2Cl2 (5 mL) were added. The organic layer was sep-
arated and the aqueous layer was extracted into CH2Cl2. The com-
bined organic extracts were dried with magnesium sulfate and con-
centrated. Products were characterized by NMR spectroscopy and
the data were consistent with those reported. Product yields were
obtained by the 1H NMR integration compared to the internal
standard. Some compounds were purified by chromatography and
[(PNO)RuCl(CO)2] (4): A mixture of PNO-H (97 mg, 0.25 mmol),
[RuCl2(CO)3(THF)] (82 mg, 0.25 mmol) and triethylamine
(0.5 mL) in THF (3 mL) was heated to reflux for 5 h. Upon cool-
ing, the reaction mixture was filtered to give 4 as an orange solid
(97 mg, 67%). IR (THF): ν = 2053, 2000 cm–1 (νC=O). 1H NMR
˜
(400 MHz, CDCl3): δ = 8.68 (s, 1 H, HC=N), 8.04 (dd, J = 8.0, J
= 12.0 Hz, 2 H, Ar-H), 7.82 (dd, J = 4.0, J = 8.0 Hz, 1 H, Ar-H),
7.60 (t, J = 8.0 Hz, 1 H, Ar-H), 7.56–7.27 (m, 11 H, Ar-H), 7.20
(d, J = 8.0 Hz, 1 H, Ar-H), 7.00 (d, J = 8.0 Hz, 1 H, Ar-H), 6.51
(t, J = 8.0 Hz, 1 H, Ar-H) ppm. 31P NMR (161 MHz, CDCl3): δ
1
characterized by NMR spectroscopy. H NMR spectroscopic data
of these compounds are essentially similar to those reported.
N-Benzylaniline: 1H NMR (400 MHz, CDCl3): δ = 7.21–7.35 (m, 5
H), 7.14 (m, 2 H), 6.71 (t, 1 H, JHH = 7 Hz), 6.59 (d, 2 H, J =
7 Hz), 4.27 (s, 2 H), 3.93 (br., 1 H) ppm.
N-(p-Chlorobenzyl)aniline: 1H NMR (400 MHz, CDCl3): δ = 7.12–
7.28 (m, 6 H), 6.71 (t, JHH = 7.7 Hz, 1 H), 6.57 (d, JHH = 7.7 Hz,
2 H), 4.28 (s, 2 H), 4.02 (br., 1 H) ppm.
= 51.0 ppm. 13C NMR (100 MHz, CDCl3): δ = 193.9 (d, JCP
12.0 Hz, C=O), 191.3 (d, JCP = 12.0 Hz, C=O), 170.2, 161.0, 156.4
(d, JCP = 19.0 Hz), 137.2, 137.2, 134.9 (d, JCP = 11.0 Hz), 134.1 (d,
JCP = 51.0 Hz), 133.8, 133.6, 131.9, 131.3 (d, JCP = 10.0 Hz), 131.2,
=
129.2 (d, JCP = 11.0 Hz), 128.8 (d, JCP = 11.0 Hz), 127.7 (d, JCP
=
56.0 Hz), 127.4 (d, JCP = 7.0 Hz), 125.8 (d, JCP = 56.0 Hz), 124.2
(d, JCP = 6.0 Hz), 120.3, 118.1 (d, JCP = 10.0 Hz), 115.2 ppm.
C27H19ClNO3PRu (572.95): calcd. C 56.60, H 3.34, N 2.44; found
C 56.93, H 3.64, N 2.16.
1
N-(p-Methylbenzyl)aniline: H NMR (400 MHz, CDCl3): δ = 7.23
(m, 7 H), 6.68 (m, 3 H), 4.23 (s, 2 H), 3.81 (br., 1 H), 2.32 (s, 3 H)
ppm.
[P,N-(PNO-Me)Ru(dmso)2Cl2] (5): A mixture of PNO-Me (198 mg,
0.5 mmol) and [RuCl2(dmso)4] (164 mg, 0.48 mmol) in THF (5 mL)
was heated to reflux for 6 h under a nitrogen atmosphere. During
the reaction, an orange solid formed. The solid was collected by
N-(p-Methoxybenzyl)aniline: 1H NMR (400 MHz, CDCl3): δ =
7.61–7.39 (m, 4 H), 6.91 (d, JHH = 7.7 Hz, 2 H), 6.72 (t, JHH
=
7.7 Hz, 1 H), 6.21 (d, JHH = 7.7 Hz, 2 H), 4.24 (s, 2 H), 3.95 (br.,
1 H), 3.81 (s, 3 H) ppm.
1
filtration to give 5 (64 mg, 47%). H NMR (400 MHz, CDCl3): δ
1
N-(Naphthalen-2-ylmethyl)aniline: H NMR (400 MHz, CDCl3): δ
= 9.60 (s, 1 H, HC=N), 8.23 (dd, JHH = 8.0, JHH = 12.0 Hz, 2 H,
Ar-H), 7.57–7.14 (m, 14 H, Ar-H), 6.97 (d, JHP = 8 Hz, 1 H, Ar-
H), 6.93 (d, JHP = 8 Hz, 1 H, Ar-H), 3.80 (s, 3 H, OMe), 3.69 (s,
3 H, dmso), 3.52 (s, 3 H, dmso), 3.29 (s, 3 H, dmso), 2.82 (s, 3
H, dmso) ppm. 31P{1H} NMR (161 MHz, CDCl3): δ = 60.8 ppm.
= 7.71 (m, 4 H), 7.37 (m, 3 H), 7.09 (m, 2 H), 6.62 (d, JHH
=
9.2 Hz, 1 H), 6.57 (d, JHH = 10.2 Hz, 2 H), 4.40 (d, 2 H), 4.22 (br.,
1 H) ppm.
N-(2-Furfurylmethyl)aniline: 1H NMR (400 MHz, CDCl3): δ = 7.34
13C{1H} NMR (100 MHz, CDCl3): δ = 173.9, 158.5, 154.3 (d, JCP (d, JHH = 1.0 Hz, 1 H), 7.19 (t, JHH = 7.2 Hz, 2 H), 6.72 (t, JHH
=
= 16.0 Hz), 137.8 (d, JCP = 11.0 Hz), 136.7 (d, JCP = 45.0 Hz), 7.2 Hz, 1 H), 6.67 (d, JHH = 7.2 Hz, 2 H), 6.32 (m, 1 H), 6.23 (m,
134.7 (d, JCP = 50.5 Hz), 134.0 (d, JCP = 14.9 Hz), 133.2, 131.7, 1 H), 4.30 (s, 2 H), 3.99 (br., 1 H) ppm.
Eur. J. Inorg. Chem. 2011, 4801–4806
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4805

C.-C. Lee, W.-Y. Chu, Y.-H. Liu, S.-M. Peng, S.-T. Liu
N-Benzyl-p-methylaniline: H NMR (400 MHz, CDCl3): δ = 7.25– = 0.15ϫ0.10ϫ0.05 mm3; reflections collected: 13714; independent
FULL PAPER
1
7.32 (m, 5 H), 6.94–6.97 (d, JHH = 8.0 Hz, 2 H), 6.51–6.54 (d, JHH
= 8.0 Hz, 2 H), 4.29 (s, 2 H), 2.21 (s, 3 H) ppm.
reflections: 5717 [R(int) = 0.0350]; θ range 2.35 to 27.50°; good-
ness-of-fit on F2 = 0.817; final R indices [IϾ2σ(I)]: R1 = 0.0384,
wR2 = 0.0759; R indices (all data): R1 = 0.1163, wR2 = 0.0898.
N-Benzyl-p-chlorolaniline: 1H NMR (400 MHz, CDCl3): δ = 7.13
(d, J = 7.2 Hz, 2 H), 7.03–7.08 (m, 5 H), 6.36 (d, J = 7.2 Hz, 2 H),
4.32 (s, 2 H), 4.03 (br., 1 H) ppm.
N-Benzyl-p-methoxyaniline: 1H NMR (400 MHz, CDCl3): δ =
7.37–7.31 (m, 5 H), 7.25 (d, J = 6.9 Hz, 2 H), 6.75 (d, J = 6.9 Hz,
2 H), 4.25 (s, 2 H), 3.72 (s, 3 H) ppm.
¯
Complex 6·(C2H5OC2H5)0.5
:
Triclinic; space group P1;
a
=
9.3298(2), b = 10.6879(3), c = 16.2407(4) Å; α = 97.142(2), β =
98.051(2), γ = 114.524(2)°; V = 1428.60(6) Å3; Z = 2; ρcalcd.
=
1.535 mgm–3; F(000) 670; crystal size = 0.20ϫ0.15ϫ0.10 mm3; re-
flections collected: 32338; independent reflections: 6543 [R(int) =
0.0484]; θ range 2.81 to 27.50°; goodness-of-fit on F2 = 0.909; final
R indices [IϾ2σ(I)]: R1 = 0.0330, wR2 = 0.1076; R indices (all
data): R1 = 0.0383, wR2 = 0.1140.
1
N-(Anthracen-2-yl)benzylamine: H NMR (400 MHz, CDCl3): δ =
8.21 (s, 1 H), 8.09 (s, 1 H), 7.89 (d, J = 8.3 Hz, 1 H), 7.80 (d, J =
6.7 Hz, 1 H), 7.78 (d, J = 9.0 Hz, 1 H), 7.23–7.44 (m, 7 H), 6.93
(d, J = 9.0 Hz, 1 H), 6.88 (s, 1 H), 4.45 (s, 2 H) ppm.
4-(Benzylamino)pyridine: 1H NMR (400 MHz, CDCl3): δ = 8.19–
8.21 (m, 2 H), 7.26–7.40 (m 5 H), 6.47 (m, 2 H), 4.55 (br., 1 H),
4.38 (s, 2 H) ppm.
N-Benzylcyclohexylamine: 1H NMR (400 MHz, CDCl3): δ = 7.24
(m, 5 H), 3.74 (s, 2 H), 2.41 (m, 1 H), 1.90–1.86 (m, 2 H), 1.68–
1.40 (m, 4 H), 1.11 (m, 5 H) ppm.
N-Benzylpiperidine: 1H NMR (400 MHz, CDCl3): δ = 1.43–1.45
(m, 2 H), 1.52–1.62 (m, 4 H), 2.35 (t, J = 5.2 Hz, 4 H), 3.46 (s, 2
H), 7.23–7.32 (m, 5 H) ppm.
Acknowledgments
We thank the National Science Council for financial support
(NSC97-2113-M-002-013-MY3).
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2002, 21, 3203–3207; b) P.-Y. Shi, Y.-H. Liu, S.-M. Peng, S.-T.
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1.50 (m, 8 H), 1.32–0.89 (m, 12 H), 0.77 (br., 1 H) ppm.
N-Benzylaniline by Direct Amination of Nitrobenzene with Benzyl
Alcohol: A mixture of nitrobenzene (0.3 mmol), 4 (0.003 mmol) and
tBuOK (0.9 mmol) in benzyl alcohol (3.6 mmol) was placed in a
flask under atmospheric pressure of nitrogen and heated by an oil
bath at 150 °C for 24 h. On completion of the reaction, brine
(3 mL) and CH2Cl2 (5 mL) were added. The organic layer was sep-
arated and the aqueous layer was extracted into diethyl ether. The
combined organic extracts were dried with magnesium sulfate and
concentrated. Products were characterized by NMR spectroscopy.
1H NMR (400 MHz, CDCl3): δ = 7.21–7.35 (m, 5 H), 7.14 (dd,
JHH = 7, 7 Hz, 2 H), 6.71 (t, JHH = 7 Hz, 1 H), 6.59 (d, J = 7 Hz,
2 H), 4.27 (s, 2 H), 3.93 (br., 1 H) ppm, which are identical to the
authentic sample of N-benzylaniline.
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703.
Crystallography: Crystals suitable for X-ray determination were ob-
tained for 2·(CH2Cl2)0.5(H2O)0.5, 4 and 6·(C2H5OC2H5)0.5 by
recrystallization at room temperature. Cell parameters were deter-
mined with a Siemens SMART CCD diffractometer. The structure
was solved using the SHELXS-97 program[13] and refined using the
SHELXL-97 program[14] by full-matrix least-squares on F2 values.
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Göttingen, Germany, 1997.
CCDC-830870 (for 2), -830871 (for 4) and -830872 (for 6) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Complex 2·[(CH2Cl2)0.5(H2O)0.5]: Monoclinic; space group P21/n; a
= 16.3229(2), b = 12.4424(2), c = 22.0748(3) Å; α = 90, β =
93.118(1), γ = 90°; V = 4476.7(1) Å3; Z = 4; ρcalcd. = 1.355 mgm–3;
F(000) 1872; crystal size = 0.30ϫ0.25ϫ0.20 mm3; reflections col-
lected: 29935; independent reflections: 10239 [R(int) = 0.0522]; θ
range 1.51 to 27.50°; goodness-of-fit on F2 = 1.054; final R indices
[IϾ2σ(I)]: R1 = 0.0493, wR2 = 0.1573; R indices (all data): R1 =
0.0722, wR2 = 0.1749.
Complex 4: Monoclinic; space group P21/c; a = 15.754(1), b =
14.784(3), c = 11.0385(6) Å; α = 90, β = 103.701(7), γ = 90°; V =
2497.9(5) Å3; Z = 1; ρcalcd. = 1.523 mgm–3; F(000) 1152; crystal size
Received: June 25, 2011
Published Online: September 7, 2011
4806
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4801–4806