Ruthenium halide complexes as N-alkylation catalysts

Article abstract of DOI:10.1002/ejic.201400117

A range of ruthenium-arene compounds with chloride, bromide or iodide ligands were prepared and tested as catalysts for the homogeneous redox neutral alkylation of tert-butylamine with phenethyl alcohol, and compared to the previously reported catalyst [R

Full text of DOI:10.1002/ejic.201400117

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DOI:10.1002/ejic.201400117
Ruthenium Halide Complexes as N-Alkylation Catalysts
Andrea Rodríguez-Bárzano,[a] Joel D. A. Fonseca,[a]
A. John Blacker,[a] and Patrick C. McGowan*[a]
Keywords: Homogeneous catalysis / Ruthenium / Alkylation / Phosphane ligands / Arene ligands / Halides
A range of ruthenium-arene compounds with chloride, brom- of the diphosphine 1,1Ј-bis(diphenylphosphino)ferrocene
ide or iodide ligands were prepared and tested as catalysts
for the homogeneous redox neutral alkylation of tert-
butylamine with phenethyl alcohol, and compared to the pre-
viously reported catalyst [RuCl2(p-cymene)]2, in the presence
(dppf). The best catalytic activities were obtained with ruth-
enium iodide compounds. The formation of either [RuX(p-
cymene)(dppf)][X] or [(RuX2(p-cymene))2(dppf)] (X = halide)
under the catalytic conditions employed was investigated.
pentamethylcyclopentadienyl),[5] or the water soluble
[Cp*Ir(NH3)3][I]2, used for the N-alkylation of aqueous am-
monia.[6] Some of the first examples of N-alkylations cata-
lysed by ruthenium complexes were reported by Watanabe
et al.,[7] who studied the N-alkylation of 2-aminopyridine
with ethanol[7f] and some N-heterocyclisations to produce
piperidine, morpholine and piperazine derivatives from a
variety of amines and alcohols.[7b] The catalysts used in
these cases were RuCl2(PPh3)3 and [Ru(cod)(cot)] (cot =
1,3,5,7-cyclooctatetraene), but high temperatures of 180–
200 °C were required. The Rigo group has analysed the N-
methylation of primary and secondary alkylamines using
methanol at reflux as both solvent and alkylating agent,
and obtained the best outcomes using [Ru(η5-C5H5)-
Cl(PPh3)2].[8]
More recently, Williams and co-workers discovered the
favourable combination of [RuCl2(p-cymene)]2 (1a) and di-
phosphines at reflux in toluene for the N-alkylation of pri-
mary or secondary amines.[9] The optimum conditions were
obtained with dppf (1,1Ј-bis(diphenylphosphino)ferrocene)
or DPEphos [bis(2-diphenylphosphinophenyl) ether] as li-
gands, after a reaction time of 24 h. The system was also
successful in reactions between primary amines and diols,
producing N-heterocycles, between secondary alcohols and
amines, and between primary alcohols and sulfonamides.
However, in these two last cases, temperatures of 150 °C in
xylene were needed to achieve complete conversion.[10]
Herein we report our investigations into the N-alkylation
of tert-butylamine with phenethyl alcohol (Scheme 1).
There are a number of catalyst features that can be varied,
including i) the arene ring and its functional groups, ii) the
halides (Ru-Cl, Ru-Br or Ru-I), and iii) the general struc-
ture of the catalyst (dimeric or monomeric). To evaluate the
importance of each of these elements, we explored the ac-
tivity of a range of functionalised arene-ruthenium dimers
2a–e and p-cymene-ruthenium pyridine monomers 3a–j. We
were also interested in evaluating various aspects of the
Introduction
Redox neutral alkylations or N-alkylations between
alcohols and amines are industrially relevant processes in
which, after initial oxidation of the alcohol, condensation
with the amine produces an imine, which is finally reduced
to yield an N-alkylated amine. The overall reaction is aided
by a transition metal catalyst that “borrows” hydrogens
from the starting alcohol and then transfers them to the
imine. This mechanism is generally referred to as “hydrogen
borrowing” or “hydrogen autotransfer” process (Fig-
ure 1).[1] These transformations are good examples of atom
economy because the only by-product generated is water,
from condensation of the aldehyde and amine. Other tradi-
tional methods for the alkylation of amines include the use
of toxic alkyl halides that, apart from producing salts as by-
products, hinder the control of mono-alkylations,[2] and the
reductive amination of carbonyl compounds.[3] The advan-
tages of using alcohols as alkylating agents include i) their
low toxicity, ii) ease of availability and high stability, and
iii) their low cost.
Figure 1. General scheme for N-alkylation of amines with alcohols.
N-Alkylations have been successfully achieved using irid-
ium catalysts, such as [Ir(cod)Cl]2 (cod = 1,5-cycloocta-
diene) with dppf,[4] the SCRAM catalyst [Cp*IrI2]2 (Cp* =
[a] School of Chemistry, University of Leeds
Woodhouse Lane, Leeds, LS2 9JT, UK
E-mail: P.C.McGowan@leeds.ac.uk
http://www.chem.leeds.ac.uk/People/McGowan.html
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catalytic system, including the effect of a diphosphine and ranging from 31 to 87% (Scheme 2). Compounds 2a, 2c
the need for a base and molecular sieves. With this in mind, and 2d had been previously reported by Sheldrick et al.[11]
we screened the homogeneous catalytic activities of the following the method initially developed by Bennett and
aforementioned complexes in the presence of dppf and Smith,[12] and this procedure was adapted for the synthesis
compared them to the [RuCl2(p-cymene)]2 (1a) system re- of 2b and 2e. The new compounds were characterised by
ported by Williams.[9] We extended the work by studying 1H and 13C NMR spectroscopy and elemental analysis.
the possible species formed upon reaction of the ruthenium
complexes with dppf, which could act as a pre-catalyst for
the transformation.
Synthesis and Characterisation of the p-Cymene-Ruthenium
Pyridine Monomers 3a–j
[RuCl2(p-cymene)]2 (1a)[12] and [RuI2(p-cymene)]2
(1b),[13] prepared according to literature methods, and com-
mercially available pyridines were used as starting materials
for the syntheses of compounds 3a–j, with the reactions
taking place in dichloromethane at room temperature
Scheme 1. N-alkylation of tert-butylamine with phenethyl alcohol.
1
(Scheme 3). These complexes were characterised by H and
13C NMR spectroscopy, mass spectrometry and elemental
analysis. The syntheses of the monomers 3a,[12] 3c[14] and
3i[15] and the crystal structure of compound 3c[14] had been
previously reported in the literature. Complexes 3a, 3d, 3e,
3g and 3i crystallised by diffusion of diethyl ether or pent-
ane into saturated solutions of the compounds in dichloro-
methane or chloroform and their representative molecular
structures are shown in Figures 2 and 3. Selected bond
lengths and angles for these five complexes are given in
Table 1. In all of the structures, the ruthenium centre occu-
pies a distorted octahedral environment, in an arrangement
Results and Discussion
Synthesis and Characterisation of the Functionalised Arene-
Ruthenium Dimers 2a–e
The starting materials (1,4-cyclohexadien-1-yl)acetic acid
and 4-(1,4-cyclohexadien-1-yl)butyric acid) for the synthe-
ses of these complexes were prepared according to a litera-
ture procedure.[11] From these, the reactions with a ruth-
enium precursor of the type RuX3 (X = Cl or Br) in acet-
one/water or ethanol produced complexes 2a–e in yields
Scheme 2. General method for the synthesis of the functionalised
arene-ruthenium dimers 2a–e.
Scheme 3. General method for the synthesis of the p-cymene-ruth-
enium pyridine monomers 3a–j.
Figure 2. ORTEP structures of 3a, 3d, 3e and 3g with thermal ellipsoids set at 50% probability. Hydrogen atoms omitted for clarity.
1975
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Table 1. Selected bond lengths [Å] and angles [°] in the structures of compounds 3a, 3d, 3e, 3g and 3i.
3a
3d
3e
3g
3i
Ru(1)–N(1)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
Ru(1)–Ring centroid
Ru(1)–C(arene)
2.1720(15)
2.4382(5)
2.4514(5)
1.686
2.1505(17)
2.4389(5)
2.4313(6)
1.675
2.1397(13)
2.4174(4)
2.4009(4)
1.662
2.1371(17)
2.4165(5)
2.4083(5)
1.670
2.1348(16)
2.4254(5)
2.4198(5)
1.663
2.219
2.201
2.187
2.189
2.189
Cl(1)–Ru(1)–Cl(2)
N(1)–Ru(1)–Cl(1)
87.446(18)
86.84(4)
87.07(2)
87.26(5)
87.344(15)
85.70(4)
87.97(2)
86.34(5)
88.858(18)
85.40(4)
typically known as “pseudo-tetrahedral” geometry (“piano used without the presence of a ruthenium species. A loading
stool” or “half sandwich” structure).[16] The η6-π-bonded of 5 mol-% of Ru was employed. The reactions were moni-
arene occupies one vertex of the tetrahedron, with the other tored by GC over a period of 24 h, and the catalytic activi-
three ligands in the remaining three sites. Compound 3d ties are illustrated in Figure 4 and summarised in Table 2.
shows intermolecular hydrogen bonding between O(1)–H
and Cl(1) with a O···Cl distance of 3.178 Å and between
C(3)–H and Cl(1) with a C···Cl distance of 3.683 Å in the
solid state. Each molecule interacts doubly with two neigh-
bouring molecules.
Figure 4. Catalytic activity of complexes 1a, RuCl3 and 2a–e for the
N-alkylation of tert-butylamine (3 mmol) with phenethyl alcohol
(3 mmol) in toluene (10 mL) at 110 °C with 5 mol-% Ru and 5 mol-
% dppf. Conversions monitored over 24 h by GC.
Complexes 2a, 2b, 2d, 2e and 1a all provided very high
conversions above 99.5% after 24 h, but at different rates.
Complexes 2a and 2e gave conversions above 96% after 9 h,
improving the catalytic activity of 1a (Table 2, Entries 1, 6
and 7). The reaction with complex 2a achieved almost 50%
conversion after 3 h (Table 2, Entry 1). It is notable that
Figure 3. ORTEP structure of 3i with thermal ellipsoids set at 50%
probability. Hydrogen atoms omitted for clarity.
between the chloride complexes 2a and 2d, the one with an
acid (2a) was the most active (Table 2, Entries 1 and 5),
Catalytic Screening of the Functionalised Arene-Ruthenium
Dimers 2a–e
whereas between the bromide complexes 2b and 2e, com-
Complexes 2a–e, 1a and RuCl3·3H2O were tested as cata- plex 2e (an ester) showed a faster reaction rate (Table 2,
lysts for the N-alkylation of tert-butylamine with phenethyl Entries 3 and 6). In fact, complexes 2b and 2d behaved as
alcohol in toluene at 110 °C (Scheme 1). Dppf was em- slightly worse catalysts than 1a (Table 2, Entries 3 and 5).
ployed in all cases in a 1:1 ratio with ruthenium, after con- Compound 2c reached 84.4% conversion after 24 h, sug-
firming that the conversions obtained without the diphos- gesting that its longer chain might have a negative effect on
phine did not exceed 3% for the formation of N-phenethyl- catalytic activity (Table 2, Entry 4). Interestingly,
tert-butylamine. Dppf did not give any conversion when RuCl3·3H2O also gave a moderate activity (74.5% after
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Table 2. Catalytic results for the N-alkylation of tert-butylamine with phenethyl alcohol with complexes 1a, RuCl3 and 2a–e.
Entry
Ru species
mol-%
Ru
mol-%
dppf
Conv. after
3 h [%][a]
Conv. after
9 h [%][a]
Conv. after
24 h [%][a]
1
2
3
4
5
6
7
8
2a
5
1
5
5
5
5
5
5
1
5
5
5
1
5
5
5
5
5
–
1
5
–
48.5
1.8
97.3
1.9
99.7
2.7
2a
2b
35.6
24.1
16.3
24.1
41.2
1.1
0.6
15.0
1.8
80.0
57.9
86.2
96.4
87.3
1.8
0.6
53.4
3.0
99.7
84.4
99.6
99.8
99.7
2.2
1.2
74.5
3.0
2c
2d
2e
1a
1a
9
10
11
1a
RuCl3·3H2O
RuCl3·3H2O
[a] Reaction conditions: phenethyl alcohol (3 mmol) and tert-butylamine (3 mmol) in toluene (10 mL) at reflux, maintained over 24 h.
Samples taken at 0, 20, 40, 60, 90, 120, 180, 300, 540 and 1440 min and analysed by GC.
24 h) in the presence of dppf (Table 2, Entry 10). Complexes
The maximum activities in the absence of dppf were ob-
2a and 1a were also tested with a lower loading of 1 mol- tained with complexes 1b and 3b, which reached conver-
% Ru and 1 mol-% dppf, although the activity in both cases sions of 11.8% and 8.7% respectively after 24 h (Table 3,
did not exceed 3% after 24 h (Table 2, Entries 2 and 9). All Entries 3 and 7). With the chloride species (1a, 3a and 3c
of these processes took place without the additional use of to 3j), on the other hand, no more than a final conversion
a base or molecular sieves, as opposed to the conditions of 3% was observed in any case (Table 3, Entry 5 with 3a).
initially reported for the same reaction using 1a and Therefore, the use of dppf was proven necessary to make
dppf,[9a] and under a non-dry atmosphere.
an effective catalyst, and it was employed in 5 mol-% for
every reaction thereafter.
Complexes 1b and 3b gave the best results in the presence
of dppf. Even though many chloride complexes reached
similar conversions after 24 h, iodide compounds 1b and 3b
were characterised by much higher reaction rates, affording
product yields above 75% after 3 h (Table 3, Entries 2 and
6). A comparison between these two complexes and their
chloride equivalents 1a and 3a, which only gave 41.2% and
25.3% conversions respectively after the same period of
time (Table 3, Entries 1 and 4), can be best seen in Figure 5.
Heavier halide ligands in transition metal complexes may
improve their activity due to the combination of both steric
Catalytic Screening of the p-Cymene-Ruthenium Pyridine
Monomers 3a–j
Monomers 3a–j have also been tested in the N-alkylation
of interest, and compared to dimers 1a and 1b. All of these
complexes have an η6-p-cymene unit coordinated to ruth-
enium in common, and compounds 3a–j have a labile pyr-
idine ligand where the nitrogen atom acts as a two electron
donor. The results obtained, using 5 mol-% Ru, are de-
picted in Table 3.
Table 3. Catalytic results for the N-alkylation of tert-butylamine with phenethyl alcohol with complexes 1a, 1b and 3a–j.
Entry
Ru
species
mol-%
Ru
mol-%
dppf
Conv. after
3 h [%][a]
Conv. after
9 h [%][a]
Conv. after
24 h [%][a]
1
2
3
4
5
6
7
8
1a
1b
1b
3a
3a
3b
3b
3c
3d
3e
3f
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
–
5
–
5
–
5
5
5
5
5
5
5
5
41.2
75.3
4.7
25.3
2.6
87.5
3.1
31.5
54.5
45.1
33.5
39.1
36.8
17.3
15.4
87.3
93.3
10.2
86.5
2.9
99.7
5.6
50.1
78.0
71.7
78.0
80.5
91.9
64.1
87.7
99.7
99.7
11.8
99.7
2.9
99.7
8.7
73.4
95.2
97.2
98.9
99.3
99.8
93.5
99.0
9
10
11
12
13
14
15
3g
3h
3i
3j
[a] Reaction conditions: phenethyl alcohol (3 mmol) and tert-butylamine (3 mmol) in toluene (10 mL) at reflux, maintained over 24 h.
Samples taken at 0, 20, 40, 60, 90, 120, 180, 300, 540 and 1440 min and analysed by GC.
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and electronic factors,[17] as seen in dynamic kinetic resolu-
tion processes, where the SCRAM catalyst [Cp*IrI2]2 per-
forms better that its analogue [Cp*IrCl2]2.[18] However, a
previous example of ruthenium catalysis using pentaphen-
ylcyclopentadienyl-RuX complexes (X = Cl, Br or I) for the
racemisation of chiral alcohols did not show a significant
effect of the halides on the catalytic activity.[19]
Figure 6. Catalytic activity of complexes 3e–h in the N-alkylation
of tert-butylamine (3 mmol) with phenethyl alcohol (3 mmol) in
toluene (10 mL) at 110 °C with 5 mol-% Ru and 5 mol-% dppf.
Conversions monitored over 24 h by GC.
Investigation of the Formation of dppf Species
After their studies on the redox neutral alkylation of tert-
butylamine with phenethyl alcohol using 1a and diphos-
phines, Williams and co-workers proposed the formation of
[RuCl(p-cymene)(P–P)][Cl] species as a pre-catalyst for the
transformation.[10] As a consequence, the use of twice the
amount of the corresponding diphosphine was reported (i.e.
[1:1] Ru/diphosphine), which we initially applied in our in-
vestigations. We have isolated the complexes [RuCl(p-
cymene)(dppf)][Cl] (4a) and [RuCl(p-cymene)(dppf)][BF4]
(4b) (Figure 7), both synthesised using alcohols as solvents,
from 1a and dppf in a 1:2 stoichiometric ratio. Similar
charged monomers with PF6 or SnCl3 as counterions had
been reported before,[20] including their crystal struc-
tures,[20a,20e] which showed an eclipsed conformation of the
cyclopentadienyl rings. However, no catalytic studies were
reported. The 1H NMR spectra of complexes 4a and 4b are
characterised by two peaks for the aromatic protons of their
p-cymene rings, and four singlets for the protons in the cy-
clopentadienyl rings.
Figure 5. Catalytic activity of complexes 1a, 1b, 3a and 3b in the
N-alkylation of tert-butylamine (3 mmol) with phenethyl alcohol
(3 mmol) in toluene (10 mL) at 110 °C with 5 mol-% Ru and 5 mol-
% dppf. Conversions monitored over 24 h by GC.
Between the two iodide complexes, compound 1b showed
lower activity than monomer 3b, which maintained its fast
rate after three hours (Figure 5 and Table 3, Entries 2 and
6). Clear differences can also be noticed for the chloride
compounds; complexes 3c and 3i were particularly slow and
gave low conversions even after 24 h (Table 3, Entries 8 and
14), whereas reactions containing 3h reached almost 92%
conversion after 9 h, highlighting the fastest complex
among the chloride derivatives (Table 3, Entry 13). These
variations might be the result of different electronic and ste-
ric properties of the pyridine ligands involved, which might
influence the expected de-coordination from ruthenium to
allow the formation of the active species with dppf (see be-
low). For instance, one notable case is that of 3-halopyrid-
ine complexes 3e–3h. For these four compounds, the ac-
tivity decreased in the order 3hϾ3gϾ3fϾ3e, more notice-
ably in the range between 300 and 1440 min, as shown in
Figure 6. In other words, the iodo substitution in the pyr-
idine resulted in a better performance than, successively, the
bromo, chloro and fluoro substitutions at the same posi-
tion, in a directly proportional relationship to the covalent
radii of the halides and inversely proportional relationship
to their electronegativities.
Figure 7. Representation of the complexes 4a–c.
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Figure 8. ORTEP structure of 4c with thermal ellipsoids set at 50% probability. Hydrogen atoms omitted for clarity.
From the same reaction of 1a and dppf in a 1:2 or 1:1 specific conditions employed for the N-alkylation of tert-
stoichiometric ratio, when performed in a non protic sol- butylamine with phenethyl alcohol. The experiments con-
vent such as dichloromethane or chloroform, we have iso- sisted on mixing 1 or 2 equiv. of dppf with 1a in toluene at
lated dimer 4c with the formula [(RuCl2(p-cymene))2(dppf)] reflux, and the species detected by NMR was, in all cases,
(Figure 7). This compound has previously been pre- 4c. We assumed that formation of 4a needed the presence
pared[20b,20d,21] but, to the best of our knowledge, neither of a protic solvent to stabilise the positive charge of the
its catalytic behaviour or crystal structure have been re- complex. Because phenethyl alcohol is used as the substrate
ported. The structure of complex 4c was determined by X- in the N-alkylation at 0.3 m, we repeated the control experi-
ray crystallography. Orange single crystals were obtained by ment in the presence of 0.3 m ethanol (so it could be easily
vapour diffusion of pentane into a saturated solution of the evaporated before recording the 1H NMR spectrum).
compound in dichloromethane. The asymmetric unit con- Again, the only species detected was 4c. The results are sim-
tains half of a molecule and two co-crystallised molecules ilar in the mixture of 4c with one equivalent of dppf; 4a is
of water. The molecular structure of this complex is shown
in Figure 8 and selected bond lengths and angles are given
in Table 4. Both ruthenium centres present the typical “pi-
ano stool” geometry, and the cyclopentadienyl rings are in
1
a staggered conformation. The H NMR spectrum of 4c is
characterised by the presence of a broad singlet at δ =
5.07 ppm, representative of the aromatic protons in the p-
cymene rings, and two singlets at δ = 4.17 and 3.89 ppm
indicative of the protons of the cyclopentadienyl rings in
the dppf bridge.
Table 4. Selected bond lengths [Å] and angles [°] in the structure of
compound 4c.
4c
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
Ru(1)–Ring centroid
Ru(1)–C(arene)
2.3726(10)
2.4259(10)
2.4414(10)
1.724
2.2395
Fe(1)–Ring centroid
Fe(1)–C(Cp)
Cl(1)–Ru(1)–Cl(2)
P(1)–Ru(1)–Cl(1)
1.667
2.0702
88.83(4)
88.10(3)
Figure 9. Catalytic activity of complexes 1a, 4b and 4c in the N-
alkylation of tert-butylamine (3 mmol) with phenethyl alcohol
(3 mmol) in toluene (10 mL) at 110 °C with 5 mol-% Ru and dif-
ferent equivalents of dppf (indicated in the graph). Conversions
1
After characterising both 4a and 4c by H NMR spec-
troscopy, we performed a series of control experiments to
determine which one of these species was formed under the monitored over 24 h by GC.
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TMS or residual protonated impurity of the deuterated solvent.
Microanalyses were obtained at the University of Leeds Microana-
lytical Service. Mass spectra were obtained at the University of
Leeds Mass Spectrometry Service. Gas chromatography analyses
were performed with a Hewlett–Packard Agilent HP6890 Series
GC system with a HP7683 Series injector and a capillary column
HP-5 (5% phenyl methyl siloxane) HP 19091J-413, with a length
of 30 m, a diameter of 0.32 mm and a film thickness of 0.25 μm.
The solvent used was acetonitrile.
formed only when a protic solvent such as 2-propanol, is
employed. In toluene, even in the presence of 0.3 m ethanol,
dimer 4c remains unmodified even after refluxing.
Complexes 4c and 4b (analogous to 4a) were sub-
sequently tested for the model N-alkylation, and their ac-
tivities compared to that obtained with 1 equiv. of 1a and
2 equiv. of dppf mixed in situ. The results, with 5 mol-% Ru
in all cases, can be seen in Figure 9 and Table 5. It can be
observed that compound 4c is active, giving 55% conver-
sion after 24 h (Table 5, Entry 3). When 1 equiv. of dppf
was added to 4c (2.5 mol-% of dppf), the catalytic activity
improved considerably, and matched that obtained with 4b,
indicating the possible formation of monomer 4a (Table 5,
Entries 4 and 2); this contradicts previous control experi-
ments. Curiously, the activity obtained with 1a + 2 equiv.
of dppf was optimal (Table 5, Entry 1).
(1,4-Cyclohexadiene-1-yl)acetic acid[11] and 4-(1,4-cyclohexadiene-
1-yl)butyric acid,[11] used as precursors, were prepared according
to literature procedures. All other reagents were obtained commer-
cially and used as received. Known complexes 1a,[12] 1b,[13] 2a,[11]
2c,[11] 2d,[11] 3a,[12] 3c,[14] 3i[15] and 4c[20b,20d,21] were synthesised ac-
cording to literature methods or slight variations thereof.
[RuBr2C6H5CH2COOH]2 (2b): (1,4-Cyclohexadiene-1-yl)acetic
acid (0.50 g, 3.6 mmol) was added to a round-bottomed flask with
RuBr3 (0.31 g, 0.9 mmol) in acetone/water (5:1 v/v, 6 mL). The mix-
ture was heated to reflux for 3 d, concentrated in vacuo, and the
precipitate filtered, washed with diethyl ether and dried under vac-
Table 5. Catalytic results for the N-alkylation of tert-butylamine
with phenethyl alcohol with complexes 1a, 4b and 4c with different
numbers of equivalents of dppf.
1
uum to afford a red solid (0.30 g, 82% yield). H NMR (CD3CN):
Entry
Ru
species
mol-% mol-% Conv. after Conv. after Conv. after
δ = 5.77 (m, 6 H, C6H5CH2CO2H), 5.64 (d, J = 2.9 Hz, 4 H,
C6H5CH2CO2H), 3.64 (s, 4H. C6H5CH2CO2H) ppm. 13C{1H}
NMR (CD3CN): δ = 157.6 (C6H5CH2CO2H), 116.4 (quaternary C
of C6H5CH2CO2H), 84.6 (C6H5CH2CO2H), 84.5 (C6H5CH2-
CO2H), 83.0 (C6H5CH2CO2H), 38.3 (C6H5CH2CO2H) ppm.
C16H16Br4O4Ru2 (794.06): calcd. C 24.2, H 2.0, Br 40.3; found C
24.2, H 2.1, Br 40.0.
Ru
dppf
3 h [%][a]
9 h [%][a]
24 h [%][a]
1
2
3
4
1a
4b
4c
4c
5
5
5
5
5
–
–
41.2
40.4
5.7
87.3
74.3
29.0
74.4
99.7
89.3
55.0
86.8
2.5
32.2
[a] Reaction conditions: phenethyl alcohol (3 mmol) and tert-
butylamine (3 mmol) in toluene (10 mL) at reflux, maintained over
24 h. Samples taken at 0, 20, 40, 60, 90, 120, 180, 300, 540 and
1440 min and analysed by GC.
[RuBr2C6H5CH2COOCH2CH3]2 (2e): (1,4-Cyclohexadiene-1-yl)-
acetic acid (0.50 g, 3.6 mmol) was added to a round-bottomed flask
with RuBr3 (0.31 g, 0.9 mmol) in ethanol (30 mL). The mixture was
heated to reflux for 24 h, concentrated in vacuo, and the precipitate
then filtered, washed with ethanol and dried under vacuum to af-
ford an orange solid (0.12 g, 31% yield). 1H NMR (CDCl3): δ =
5.77 (m, 2 H, C6H5CH2CO2CH2CH3), 5.67 (t, J = 5.6 Hz, 4 H,
C6H5CH2CO2CH2CH3), 5.54 (d, J = 5.6 Hz, 4 H, C6H5CH2CO2-
CH2CH3), 4.16 (q, J = 7.0 Hz, 4H. C6H5CH2CO2CH2CH3), 3.68
Conclusions
A library of arene-ruthenium complexes with either p-
cymene or carboxy-derived arenes was prepared and tested
in the N-alkylation of tert-butylamine with phenethyl
alcohol under homogeneous conditions. The catalytic ex-
periments were optimised without the need for any base
or dry atmosphere techniques. Compared to commercially
available [RuCl2(p-cymene)]2, previously used for this trans-
formation, carboxylic substitution of the arene gave im-
proved results. The best activities were obtained with ruth-
enium iodide complexes, which are much more active than
their chloride equivalents. The complexes obtained from
substituted pyridines and [RuX2(p-cymene)]2 (X = halide)
displayed different catalytic activities, which is likely related
to steric and electronic variations on the pyridines. The use
of dppf as a coordinating ligand proved necessary in all of
the cases, and the intermediate formation of both [RuX(p-
(s, 4H. C6H5CH2CO2CH2CH3), 1.26 (t,
C6H5CH2CO2CH2CH3) ppm.
J
=
7.2 Hz, 6H.
(CDCl3):
13C{1H}
NMR
δ
= 169.4 (C6H5CH2CO2CH2CH3), 92.6 (quaternary C of
C6H5CH2CO2CH2CH3), 83.8 (C6H5CH2CO2CH2CH3), 83.1
(C6H5CH2CO2CH2CH3), 82.4 (C6H5CH2CO2CH2CH3), 61.7
(C6H5CH2CO2CH2CH3), 39.7 (C6H5CH2CO2CH2CH3), 14.1
(C6H5CH2CO2CH2CH3) ppm. C20H24Br4O4Ru2 (850.16): calcd. C
28.2, H 2.9, Br 37.6; found C 28.1, H 2.8, Br 37.4.
[RuI2(p-cymene)(NC5H5)] (3b): Compound 1b (0.15 g, 0.15 mmol)
was dissolved in dichloromethane (10 mL), and pyridine (49 μL,
0.6 mmol) was added. The mixture was stirred overnight to give a
dark red solution and the solvent was evaporated to give a brown
solid (0.15 g, 88% yield). 1H NMR (CDCl3): δ = 9.48 (m, 2 H, 2,6-
CH of NC5H5), 7.72 (t, J = 6.8 Hz, 1 H, 4-CH of NC5H5), 7.20 (t,
J = 5.6 Hz, 2 H, 3,5-CH of NC5H5), 5.69 [d, J = 4.8 Hz, 2 H,
cymene)(dppf)][X] and [(RuX2(p-cymene))2(dppf)] seemed CH3C(CH)2(CH)2CCH(CH3)2], 5.32 [d,
J
=
4.8 Hz,
2 H,
CH3C(CH)2(CH)2CCH(CH3)2], 3.05 [m,
1 H, CH3C(CH)2-
to influence the catalytic behaviour displayed by all com-
plexes studied.
(CH)2CCH(CH3)2], 1.89 [br. s, 3 H, CH3C(CH)2(CH)2CCH-
(CH3)2], 1.26 [d, J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2CCH-
(CH3)2] ppm. 13C{1H} NMR (CDCl3): δ = 160.0 (2,6-CH of
NC5H5), 137.4 (4-CH of NC5H5), 124.4 (3,5-CH of NC5H5), 103.3
[CH3C(CH)2(CH)2CCH(CH3)2], 97.9 [CH3C(CH)2(CH)2CCH-
(CH3)2], 83.9 [CH3C(CH)2(CH)2CCH(CH3)2], 83.2 [CH3C(CH)2-
Experimental Section
General: All NMR spectra were recorded using a Bruker DPX
(300 MHz), a Bruker Avance (400 MHz) or a Bruker DRX (CH)2CCH(CH3)2], 31.8 [CH3C(CH)2(CH)2CCH(CH3)2], 22.9
(500 MHz) spectrometers; chemical shifts are reported relative to
[CH3C(CH)2(CH)2CCH(CH3)2], 18.8 [CH3C(CH)2(CH)2CCH-
Eur. J. Inorg. Chem. 2014, 1974–1983
1980
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
(CH3)2] ppm. MS (ES): m/z = 442.0 [MH – I]+. C15H19I2NRu
(568.20): calcd. C 31.7, H 3.4, N 2.5, I 44.7; found C 32.1, H 3.5,
N 2.5, I 44.6.
ClNC5H4), 132.5 (quaternary C of 3-ClNC5H4), 124.7 (5-CH
of 3-ClNC5H4), 103.7 [CH3C(CH)2(CH)2CCH(CH3)2], 97.3
[CH3C(CH)2(CH)2CCH(CH3)2], 82.9 [CH3C(CH)2(CH)2CCH-
(CH3)2], 82.2 [CH3C(CH)2(CH)2CCH(CH3)2], 30.7 [CH3C(CH)2-
(CH)2CCH(CH3)2], 22.3 [CH3C(CH)2(CH)2CCH(CH3)2], 18.3
[CH3C(CH)2(CH)2CCH(CH3)2] ppm. MS (ES): m/z = 384.0 [M –
Cl]+. C15H18Cl3NRu (419.74): calcd. C 42.9, H 4.3, N 3.3, Cl 25.4;
found C 42.8, H 4.3, N 3.2, Cl 25.3.
[RuCl2(p-cymene)(3-OHNC5H4)] (3d): Compound 1a (0.15 g,
0.25 mmol) was dissolved in dichloromethane (10 mL), and 3-hy-
droxypyridine (47.6 mg, 0.5 mmol) was added. The mixture was
stirred overnight and changed from a dark orange solution to an
orange suspension, which was filtered and washed with cold hexane
1
to give a yellow solid (0.15 g, 74% yield). H NMR (CDCl3): δ =
[RuCl2(p-cymene)(3-BrNC5H4)] (3g): Compound 1a (0.15 g,
0.25 mmol) was dissolved in dichloromethane (10 mL), and 3-bro-
mopyridine (96.3 μL, 1 mmol) was added. The mixture was stirred
8.63 (m, 1 H, 2-CH of 3-OHNC5H4), 8.34 (d, J = 5.1 Hz, 1 H, 6-
CH of 3-OHNC5H4), 7.02 (dd, J = 8.3, 1.5 Hz, 1 H, 4-CH of 3-
OHNC5H4), 6.89 (dd, J = 8.1, 5.6 Hz, 1 H, 5-CH of 3-OHNC5H4), overnight to give an orange solution and the solvent was evapo-
5.47 [d, J = 5.1 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.23 [d,
J = 6.0 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 2.98 [m, 1 H,
rated to give an orange solid (0.21 g, 90% yield). 1H NMR
(CDCl3): δ = 9.15 (m, 1 H, 2-CH of 3-BrNC5H4), 9.02 (d, J =
CH3C(CH)2(CH)2CCH(CH3)2], 2.04 [s, 3 H, CH3C(CH)2(CH)2- 5.6 Hz, 1 H, 6-CH of 3-BrNC5H4), 7.89 (d, J = 7.9 Hz, 1 H, 4-CH
CCH(CH3)2], 1.31 [d, J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2- of 3-BrNC5H4), 7.23 (dd, J = 7.7, 5.8 Hz, 1 H, 5-CH of 3-
CCH(CH3)2] ppm. 13C{1H} NMR (CDCl3): δ = 153.3 (quaternary
C of 3-OHNC5H4), 146.1 (6-CH of 3-OHNC5H4), 144.2 (2-CH of
BrNC5H4), 5.47 [d, J = 6.0 Hz, 2 H, CH3C(CH)2(CH)2CCH-
(CH3)2], 5.25 [d, J = 6.0 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2],
3-OHNC5H4), 126.3 (4-CH of 3-OHNC5H4), 124.6 (5-CH of 3- 2.98 [sep, J = 6.9 Hz, 1 H, CH3C(CH)2(CH)2CCH(CH3)2], 2.12
OHNC5H4), 103.5 [CH3C(CH)2(CH)2CCH(CH3)2], 97.4 [s, 3 H, CH3C(CH)2(CH)2CCH(CH3)2], 1.32 [d, J = 6.8 Hz, 6 H,
[CH3C(CH)2(CH)2CCH(CH3)2], 83.1 [CH3C(CH)2(CH)2CCH- CH3C(CH)2(CH)2CCH(CH3)2] ppm. 13C{1H} NMR (CDCl3): δ =
(CH3)2], 82.1 [CH3C(CH)2(CH)2CCH(CH3)2], 30.7 [CH3C(CH)2- 155.7 (2-CH of 3-BrNC5H4), 153.4 (6-CH of 3-BrNC5H4), 140.5
(CH)2CCH(CH3)2], 22.3 [CH3C(CH)2(CH)2CCH(CH3)2], 18.2 (4-CH of 3-BrNC5H4), 125.1 (5-CH of 3-BrNC5H4), 120.4 (quater-
[CH3C(CH)2(CH)2CCH(CH3)2] ppm. MS (ES): m/z = 366.0 [M – nary C of 3-BrNC5H4), 103.7 [CH3C(CH)2(CH)2CCH(CH3)2], 97.4
Cl]+. C15H19Cl2NORu (401.30): calcd. C 44.9, H 4.8, N 3.5, Cl
17.7; found C 44.7, H 4.8, N 3.4, Cl 17.8.
[CH3C(CH)2(CH)2CCH(CH3)2], 82.9 [CH3C(CH)2(CH)2CCH-
(CH3)2], 82.2 [CH3C(CH)2(CH)2CCH(CH3)2], 30.7 [CH3C(CH)2-
(CH)2CCH(CH3)2], 22.3 [CH3C(CH)2(CH)2CCH(CH3)2], 18.3
[CH3C(CH)2(CH)2CCH(CH3)2] ppm. MS (ES): m/z = 429.9 [M –
Cl]+. C15H18BrCl2NRu (464.19): calcd. C 38.8, H 3.9, N 3.0; found
C 38.8, H 3.9, N 2.9.
[RuCl2(p-cymene)(3-FNC5H4)] (3e): Compound 1a (0.15 g,
0.25 mmol) was dissolved in dichloromethane (10 mL), and 3-fluo-
ropyridine (86 μL, 1 mmol) was added. The mixture was stirred
overnight to give an orange solution and the solvent was evapo-
rated to give an orange solid (0.20 g, 97% yield). 1H NMR
[RuCl2(p-cymene)(3-INC5H4)] (3h): Compound 1a (0.15 g,
(CDCl3): δ = 8.99 (br. s, 1 H, 2-CH of 3-FNC5H4), 8.90 (d, J = 0.25 mmol) was dissolved in dichloromethane (10 mL), and 3-iodo-
4.8 Hz, 1 H, 6-CH of 3-FNC5H4), 7.50 (m, 1 H, 4-CH of 3- pyridine (0.20 g, 1 mmol) was added. The mixture was stirred over-
FNC5H4), 7.33 (m, 1 H, 5-CH of 3-FNC5H4), 5.46 [d, J = 5.2 Hz, night to give an orange solution that formed a suspension after
2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.25 [d, J = 5.2 Hz, 2 H, less than 5 min. This suspension was filtered and washed with cold
CH3C(CH)2(CH)2CCH(CH3)2], 2.98 [m, 1 H, CH3C(CH)2(CH)2- hexane to give a yellow solid (0.19 g, 74% yield). 1H NMR
CCH(CH3)2], 2.10 [s, 3 H, CH3C(CH)2(CH)2CCH(CH3)2], 1.31 [d,
(CDCl3): δ = 9.29 (m, 1 H, 2-CH of 3-INC5H4), 9.06 (d, J = 5.2 Hz,
J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2CCH(CH3)2] ppm. 13C{1H} 1 H, 6-CH of 3-INC5H4), 8.07 (d, J = 7.9 Hz, 1 H, 4-CH of 3-
1
NMR (CDCl3): δ = 158.7 [d, J(C-F) = 254.3 Hz; quaternary C of INC5H4), 7.10 (dd, J = 7.9, 5.6 Hz, 1 H, 5-CH of 3-INC5H4), 5.46
4
3-FNC5H4], 151.3 [d, J(C-F) = 3.8 Hz; 6-CH of 3-FNC5H4], 143.9 [d, J = 6.0 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.24 [d, J =
2
[d, J(C-F) = 31.7 Hz; 2-CH of 3-FNC5H4], 124.9 (m; 4- and 5-CH 5.6 Hz,
2 H, CH3C(CH)2(CH)2CCH(CH3)2], 2.98 [m, 1 H,
of 3-FNC5H4), 103.7 [s; CH3C(CH)2(CH)2CCH(CH3)2], 97.3 [s; CH3C(CH)2(CH)2CCH(CH3)2], 2.12 [s, 3 H, CH3C(CH)2(CH)2-
CH3C(CH)2(CH)2CCH(CH3)2], 82.8 [s; CH3C(CH)2(CH)2CCH- CCH(CH3)2], 1.33 [d, J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2-
(CH3)2], 82.3 [s; CH3C(CH)2(CH)2CCH(CH3)2], 30.7 [s; CCH(CH3)2] ppm. 13C{1H} NMR (CDCl3): δ = 160.3 (2-CH of 3-
CH3C(CH)2(CH)2CCH(CH3)2], 22.3 [s; CH3C(CH)2(CH)2CCH- INC5H4), 153.7 (6-CH of 3-INC5H4), 146.0 (4-CH of 3-INC5H4),
(CH3)2], 18.2 [s; CH3C(CH)2(CH)2CCH(CH3)2] ppm. MS (ES): m/z 125.4 (5-CH of 3-INC5H4), 103.6 [CH3C(CH)2(CH)2CCH(CH3)2],
= 368.0 [M – Cl]+. C15H18Cl2FNRu (403.29): calcd. C 44.6, H 4.5,
N 3.5, Cl 17.6; found C 44.9, H 4.5, N 3.6, Cl 18.0.
97.3 [CH3C(CH)2(CH)2CCH(CH3)2], 91.8 (quaternary C of 3-
INC5H4), 82.9 [CH3C(CH)2(CH)2CCH(CH3)2], 82.2 [CH3C(CH)2-
(CH)2CCH(CH3)2], 30.7 [CH3C(CH)2(CH)2CCH(CH3)2], 22.3
[CH3C(CH)2(CH)2CCH(CH3)2], 18.3 [CH3C(CH)2(CH)2CCH-
(CH3)2] ppm. MS (ES): m/z = 475.9 [M – Cl]+. C15H18Cl2INRu
(511.19): calcd. C 35.2, H 3.6, N 2.7; found C 35.5, H 3.5, N 2.7.
[RuCl2(p-cymene)(3-ClNC5H4)] (3f): Compound 1a (0.15 g,
0.25 mmol) was dissolved in dichloromethane (10 mL), and 3-
chloropyridine (95 μL, 1 mmol) was added. The mixture was stirred
overnight to give an orange solution and the solvent was evapo-
rated to give an orange solid (0.20 g, 96% yield). 1H NMR
[RuCl2(p-cymene)(4-BrNC5H4)] (3j): Compound 1a (0.15 g,
(CDCl3): δ = 9.05 (m, 1 H, 2-CH of 3-ClNC5H4), 8.98 (d, J = 0.25 mmol) was dissolved in dichloromethane (10 mL), and 4-bro-
5.1 Hz, 1 H, 6-CH of 3-ClNC5H4), 7.74 (d, J = 7.7 Hz, 1 H, 4-CH mopyridine hydrochloride (97.23 mg, 0.5 mmol) was added. The
of 3-ClNC5H4), 7.29 (m, 1 H, 5-CH of 3-ClNC5H4), 5.47 [d, J = mixture was stirred overnight to give an orange solution with some
6.0 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.25 [d, J = 5.1 Hz,
2 H, CH3C(CH)2(CH)2CCH(CH3)2], 2.98 [sep, J = 6.8 Hz, 1 H,
undissolved powder that was filtered, and the filtrate evaporated to
give an orange solid (0.23 g, 100% yield). H NMR (CDCl3): δ =
1
CH3C(CH)2(CH)2CCH(CH3)2], 2.11 [s, 3 H, CH3C(CH)2(CH)2- 8.87 (d, J = 5.2 Hz, 2 H, 2,6-CH of 4-BrNC5H4), 7.49 (d, J =
CCH(CH3)2], 1.32 [d, J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2- 5.6 Hz, 2 H, 3,5-CH of 4-BrNC5H4), 5.46 [d, J = 4.8 Hz, 2 H,
CCH(CH3)2] ppm. 13C{1H} NMR (CDCl3): δ = 153.7 (2-CH of 3- CH3C(CH)2(CH)2CCH(CH3)2], 5.25 [d,
J = 4.8 Hz, 2 H,
ClNC5H4), 153.0 (6-CH of 3-ClNC5H4), 137.7 (4-CH of 3-
CH3C(CH)2(CH)2CCH(CH3)2], 2.99 [m, 1 H, CH3C(CH)2(CH)2-
Eur. J. Inorg. Chem. 2014, 1974–1983
1981
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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FULL PAPER
CCH(CH3)2], 2.12 [s, 3 H, CH3C(CH)2(CH)2CCH(CH3)2], 1.32 [d,
J = 6.8 Hz, 6 H, CH3C(CH)2(CH)2CCH(CH3)2] ppm. 13C{1H} CH3C(CH)2(CH)2CCH(CH3)2], 83.6 [m; quaternary
NMR (CDCl3): δ = 155.3 (2,6-CH of 4-BrNC5H4), 135.5 (quater- (C6H5)4P2Fe(C5H4)2], 78.5 [t, J = 4.4 Hz, (C6H5)4P2Fe(C5H4)2],
[s; CH3C(CH)2(CH)2CCH(CH3)2], 90.9 [t,
J
=
4.7 Hz;
C
of
nary C of 4-BrNC5H4), 128.1 (3,5-CH of 4-BrNC5H4), 103.7 74.7 [br. s; (C6H5)4P2Fe(C5H4)2], 73.6 [m; (C6H5)4P2Fe(C5H4)2],
[CH3C(CH)2(CH)2CCH(CH3)2], 97.2 [CH3C(CH)2(CH)2CCH- 69.0 [br. s; (C6H5)4P2Fe(C5H4)2], 30.9 [s; CH3C(CH)2(CH)2-
(CH3)2], 82.8 [CH3C(CH)2(CH)2CCH(CH3)2], 82.2 [CH3C(CH)2- CCH(CH3)2], 20.9 [s; CH3C(CH)2(CH)2CCH(CH3)2], 15.7 [m;
(CH)2CCH(CH3)2], 30.7 [CH3C(CH)2(CH)2CCH(CH3)2], 22.3 CH3C(CH)2(CH)2CCH(CH3)2] ppm. MS (ES): m/z = 825.1 [M –
[CH3C(CH)2(CH)2CCH(CH3)2], 18.3 [CH3C(CH)2(CH)2CCH- Cl]+. C44H42Cl2FeP2Ru (860.59): calcd. C 61.4, H 4.9, Cl 8.2; found
(CH3)2] ppm. MS (ES): m/z = 429.9 [M – Cl]+. C15H18BrCl2NRu
C 58.8, H 5.0, Cl 8.2.
(464.19): calcd. C 38.8, H 3.9, N 3.0; found C 39.1, H 3.9, N 2.9.
[RuCl(p-cymene)(dppf)][BF4] (4b): AgBF4 (0.05 g, 0.26 mmol) and
1,1Ј-bis(diphenylphosphino)ferrocene (0.14 g, 0.26 mmol) were
added to a suspension of 1a (80 mg, 0.13 mmol) in methanol
(10 mL), and the mixture was heated to reflux for 2.5 h. The re-
sulting white precipitate was removed by filtration and the solvent
from the filtrate was evaporated to yield an orange solid, which
was recrystallised from chloroform/pentane (79 mg, 33% yield). 1H
NMR (CDCl3): δ = 7.72 [m, 6 H, (C6H5)4P2Fe(C5H4)2], 7.59 [m, 8
[RuCl(p-cymene)(dppf)][Cl] (4a): A mixture of complex 1a (0.15 g,
0.25 mmol) and 1,1Ј-bis(diphenylphosphino)ferrocene (0.28 g,
0.5 mmol) in ethanol (8 mL) and benzene (1 mL) was heated to
55 °C for 50 min and then stirred overnight. After evaporating the
solvent, dichloromethane was used to dissolve the residue and di-
ethyl ether added to precipitate a dark yellow solid. This solid was
then recrystallised from methanol/diethyl ether (0.23 g, 53% yield).
1H NMR (CDCl3): δ = 7.73 [br. s, 6 H, (C6H5)4P2Fe(C5H4)2], H, (C6H5)4P2Fe(C5H4)2], 7.46 [m, 6 H, (C6H5)4P2Fe(C5H4)2], 5.79
7.61 [br. s, H, (C6H5)4P2Fe(C5H4)2], 7.46 [br. s, H, [d, J = 5.1 Hz, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.17 [d, J =
(C6H5)4P2Fe(C5H4)2], 5.89 [br. s, 2 H, CH3C(CH)2(CH)2CCH- 6.0 Hz, H, CH3C(CH)2(CH)2CCH(CH3)2], 5.08 [s, H,
8
6
2
2
(CH3)2], 5.19 [br. s, 2 H, CH3C(CH)2(CH)2CCH(CH3)2], 5.07 [s, 2 (C6H5)4P2Fe(C5H4)2], 4.36 [br. s, 2 H, (C6H5)4P2Fe(C5H4)2], 4.27
H, (C6H5)4P2Fe(C5H4)2], 4.36 [s, 2 H, (C6H5)4P2Fe(C5H4)2], 4.27 [s, 2 H, (C6H5)4P2Fe(C5H4)2], 4.07 [br. s, 2 H, (C6H5)4P2Fe-
[s, 2 H, (C6H5)4P2Fe(C5H4)2], 4.08 [s, 2 H, (C6H5)4P2Fe(C5H4)2],
2.68 [m, H, CH3C(CH)2(CH)2CCH(CH3)2], 1.10 [s,
CH3C(CH)2(CH)2CCH(CH3)2], 0.90 [d, 6.4 Hz,
CH3C(CH)2(CH)2CCH(CH3)2] ppm. 31P{1H} NMR (CDCl3): δ =
36.44 (s) ppm. 13C{1H} NMR (CDCl3):
138.3–128.5 [(C6H5)4P2Fe(C5H4)2], 99.3 [s; CH3C(CH)2(CH)2CCH(CH3)2], 96.2
(C5H4)2], 2.65 [m, 1 H, CH3C(CH)2(CH)2CCH(CH3)2], 1.01 [s, 3
1
3 H, H, CH3C(CH)2(CH)2CCH(CH3)2], 0.89 [d, J = 7.0 Hz, 6 H,
J
=
6
H,
CH3C(CH)2(CH)2CCH(CH3)2] ppm. 31P{1H} NMR (CDCl3): δ =
36.27 (s) ppm. 13C{1H} NMR (CDCl3):
δ = 138.4–128.4
δ
=
[(C6H5)4P2Fe(C5H4)2], 99.4 [s; CH3C(CH)2(CH)2CCH(CH3)2], 96.8 [s; CH3C(CH)2(CH)2CCH(CH3)2], 90.7 [t, J = 5.1 Hz; CH3C-
Table 6. Crystallographic data for compounds 3a, 3d, 3e, 3g, 3i and 4c.
3a
3d
3e
3g
3i
4c
Formula
C
385.28
15H19Cl2NRu
C15H19Cl2NORu C15H18Cl2FNRu C15H18BrCl2NRu C17H24Cl2N2Ru
C27H28Cl2Fe0.50O2PRu
615.36
Formula weight
401.28
403.27
464.18
428.35
[gmol–1
]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
monoclinic
P21/c
10.0953(15)
7.9950(11)
20.377(3)
90
103.501(6)
90
1599.3(4)
4
monoclinic
P21/c
7.8704(9)
12.8864(16)
15.864(2)
90
103.467(5)
90
1564.7(3)
4
monoclinic
P21/c
9.9656(5)
7.9319(3)
20.0828(9)
90
103.628(2)
90
1542.77(12)
4
monoclinic
P21/c
15.2457(5)
14.8885(5)
7.3460(2)
90
92.3380(10)
90
1666.05(9)
4
monoclinic
P21/n
15.0133(5)
7.7940(2)
15.1970(5)
90
92.9020(10)
90
1775.98(9)
4
triclinic
P1
¯
9.6847(11)
11.8387(13)
12.4139(15)
76.893(5)
88.748(5)
68.900(5)
1290.5(3)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
T [K]
150(2)
1.6
1.301
0.7042
and 0.5741
150(2)
1.703
1.338
0.6304
and 0.5906
150(2)
1.736
1.361
0.6257
150(2)
1.851
3.649
0.8108
150(2)
1.602
1.181
0.7566
150(2)
1.584
1.169
0.9332
ρcalcd. [mgm–3
]
μ [mm–1
Transmission
Factors [max./
min.]
]
and 0.6052
and 0.3377
and 0.7109
and 0.7913
Crystal size [mm]
θmax [°]
0.48ϫ0.36ϫ0.29 0.44ϫ0.38ϫ0.38 0.41ϫ0.40ϫ0.38 0.38ϫ0.17ϫ0.06 0.31ϫ0.27ϫ0.25 0.21ϫ0.18ϫ0.06
30.56
30.33
30.57
30.59
30.54
30.37
Total reflections
Unique reflns.,
Rint
40917
4806, 0.0447
59192
4691, 0.0461
26291
4720, 0.0494
29733
5127, 0.0547
29896
5352, 0.0468
38704
7706, 0.0502
Reflns. with
F2 Ͼ 2σ(F2)
Parameters
R1, wR2
4454
4433
4489
4576
4670
6086
175
185
184
0.023, 0.0568
184
204
301
0.051, 0.1512
0.0202, 0.0662
0.0278, 0.0915
0.0224, 0.0649
0.0256, 0.0669
[F2 Ͼ 2σ(F2)]
R1, wR2 (all data) 0.0244, 0.0766
0.0303, 0.093
1.32
0.0245, 0.0576
1.084
0.0288, 0.0878
1.25
0.0332, 0.0791
1.15
0.0677, 0.1619
1.072
GOF (S)
1.308
Largest difference
peak and hole
0.894 and –0.989 2.08 and –1.639
0.829 and –0.54
0.697 and –0.818 0.698 and –0.65
2.88 and –1.21
[eÅ–3
]
Eur. J. Inorg. Chem. 2014, 1974–1983
1982
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
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(CH)2(CH)2CCH(CH3)2],
83.7
[m;
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C
of
(C6H5)4P2Fe(C5H4)2], 78.5 [t, J = 4.8 Hz; (C6H5)4P2Fe(C5H4)2],
74.7 [t, J = 2.3 Hz; (C6H5)4P2Fe(C5H4)2], 73.6 [t, J = 3.2 Hz;
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31.0 [s; CH3C(CH)2(CH)2CCH(CH3)2], 20.6 [s; CH3C(CH)2-
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The authors wish to acknowledge the The Technology Strategy
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Published Online: March 12, 2014
Eur. J. Inorg. Chem. 2014, 1974–1983
1983
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim