Novel pyridinium based cobalt carbonyl ionic liquids: Synthesis, full characterization, crystal structure and application in catalysis

Article abstract of DOI:10.1039/b709800f

Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts, [C₁Py][Co(CO)₄] (2a), [C ₄Py][Co(CO)₄] (2b) and [C₁₆Py][Co(CO) ₄] (2c) (C_nPy = N-C_nH_2n+1- pyridinium), were successfully prepared in good yields, using a water-organic biphasic system. All the three compounds melt well below 100 °C and could be classified as ionic liquids. The compounds were fully characterized using IR, UV-Vis, ¹H NMR, ¹³C NMR, ESI-MS and elemental analysis, and 2c was structurally characterized by X-ray single crystal analysis. Compound 2b has been found to be an efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base additive. The Royal Society of Chemistry.

Full text of DOI:10.1039/b709800f

An international journal of inorganic chemistry
www.rsc.org/dalton
Number 38 | 14 October 2007 | Pages 4229–4360
ISSN 1477-9226
PERSPECTIVE
HOT ARTICLE
Andrea F. Armstrong and
John F. Valliant
Wei Sun and Chun-Gu Xia et al.
Novel pyridinium based cobalt
carbonyl ionic liquids
The bioinorganic and medicinal
chemistry of carboranes
1477-9226(2007)38;1-#

PAPER
www.rsc.org/dalton | Dalton Transactions
Novel pyridinium based cobalt carbonyl ionic liquids: synthesis, full
characterization, crystal structure and application in catalysis†‡
Fan-Guo Deng,a,b Bin Hu,a Wei Sun,*a Jing Chena and Chun-Gu Xia*a
Received 28th June 2007, Accepted 3rd August 2007
First published as an Advance Article on the web 15th August 2007
DOI: 10.1039/b709800f
Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts,
[C1Py][Co(CO)4] (2a), [C4Py][Co(CO)4] (2b) and [C16Py][Co(CO)4] (2c) (CnPy = N-CnH2n+1-pyridinium),
were successfully prepared in good yields, using a water–organic biphasic system. All the three
compounds melt well below 100 ◦C and could be classified as ionic liquids. The compounds were fully
characterized using IR, UV-Vis, 1H NMR, 13C NMR, ESI-MS and elemental analysis, and 2c was
structurally characterized by X-ray single crystal analysis. Compound 2b has been found to be an
efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base
additive.
compound [bmim][Co(CO)4] has been cited interestedly by many
Introduction
researchers,3,6–9,27–31 further exploration has been scarcely made till
now.26 Besides, despite the commonly favorable catalytic activities
of the metal carbonyl species, reports on such organometallic ionic
liquids have been more focused on their conventional reactivities,
instead of serving as catalysts.6,8,9,25 In this paper, we report the
convenient synthesis of a series of novel alkylpyridinium cobalt
carbonyl ionic liquids based on an improved synthetic method,
as well as detailed characterizations and the first crystal structure
of a so-called cobalt carbonyl ionic liquid. Moreover, preliminary
studies on the catalytic application of these materials have also
been carried out, and the results are satisfactory.
Among the vast research work related to ionic liquids nowadays,
task specific ionic liquids (TSILs) are receiving growing attention
because of their tunable features for various chemical tasks.1–4 In
previously published papers, an increasing number of transition
metal carbonyl species have been introduced to TSILs, to afford
so-called “organometallic ionic liquids”,5–9 which show attractive
advantages such as better stability and solubility, comparative or
even enhanced catalytic activity and considerable reusability5,10
over the conventional organometallic catalysts. And one of the
most interesting species to be involved is [Co(CO)4]−, a versatile
species for a number of catalytic reactions.11–15 For example,
previous work has shown that [bmim][Co(CO)4] (bmim = 1-butyl-
3-methylimidazolium) is an efficient and recyclable catalyst and
solvent for the debromination of bromo-phenones.5 And the
non-ionic-liquid type compounds [Lewis acid]+[Co(CO)4]− also
exhibited excellent performances in catalysis.16–19
Results and discussion
Preparations: solvent considerations
The choice of the solvent used plays an important role in
the syntheses. Generally, we found that water is a preferred
solvent for preparation, and the water–organic biphasic system
works comparatively better in such syntheses. While we originally
adopted the commonly used synthetic strategies for metal car-
bonyl ionic liquids, where organic solvents such as acetone5 and
methanol24 were used as the reaction medium, certain difficulties
were encountered. First, if acetone was used as the solvent, the
reactant 1 was hardly dissolved, which may cause inconvenience
in the reactant injection and a decrease in the reaction efficiency.
Second, the byproduct, which might somewhat dissolve in acetone,
would contaminate the resulting ionic liquid;24 and in the case
where methanol was used as the solvent,24 although no byproduct
was produced in the reaction, the effective elimination of the excess
or remaining reactants from the product still remains a problem,
since they are all soluble in methanol. Finally, the main problem
in these strategies is that both the reactants, which are soluble in
the organic solvents, might more or less remain in the reaction
mixture, and thus could not be removed by simple filtration.
The water–organic biphasic system is a widely used method
in numerous phase-transfer assisted biphasic catalytic reactions,
which is reliable and consistently gives good yields. Inspired by
Hitherto, a mass of ionic compounds containing [Co(CO)4]−
have been synthesized and characterized successively,20–23 however,
most of them were presented and investigated as conventional
salts, rather than ionic liquids; on the other hand, throughout
the reports on the ionic liquids bearing transition metal carbonyl
anions as the functional groups,5,9,24,25 few have put forward
detailed characterizations and the structures of the compounds,
which might usually be helpful in giving better insight into the
studies related to catalysis, and to other explorations on the
applications of the compounds to new functionalities. Especially
for [Co(CO)4]−, although the first and only report5,26 on the new
aState key laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou
Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou,
730000, P R China. E-mail: wsun@lzb.ac.cn, cgxia@lzb.ac.cn; Fax: +86-
931-8277088; Tel: +86-931-4968278
bGraduate School of Chinese Academy of Sciences, Beijing, 100039, P R
China
† CCDC reference number 647942. For crystallographic data in CIF or
other electronic format see DOI: 10.1039/b709800f
‡ Electronic supplementary information (ESI) available: Characteriza-
tion data (IR, NMR), details of carbonylation reactions. See DOI:
10.1039/b709800f
4262 | Dalton Trans., 2007, 4262–4267
This journal is
The Royal Society of Chemistry 2007
©

Table 1 Solid-state IR spectra of 2 and some conventional salts of
this, in the redesigning of our synthetic experiments, the salts
2a–2c were obtained by metathesis in water, instead of organic
solvents, which has been a widely used method in liquid–liquid
biphasic catalysis. Unlike most organometallic compounds, which
are usually sensitive to water as well as oxygen, this reaction, albeit
very sensitive to oxygen, goes on smoothly without degradation in
degassed water. Both the reactants (KCo(CO)4 and 2) were then
easily dissolved and well commixed in water, and the reactions
were completed momentarily. The product 2, which is immiscible
with water, was the only compound soluble in the organic phase
in the reaction mixture. Therefore, after simple phase-separation,
clean product 2 was obtained directly from the organic solution.
Mostly due to compact ion pairing (see the IR/NMR/X-ray
part), these compounds have shown comparatively better air
stabilities compared to analogous conventional [Co(CO)4]− salts
such as NaCo(CO)4 and KCo(CO)4. The compounds 2a–2c are all
able to be handled briefly in air, and the most stable compound
2c remains physically and spectroscopically unchanged after 24 h
of exposure to the air at room temperature. The general synthetic
route of 2 is given in Scheme 1.
[Co(CO)4]−a
NaCo(CO)4
[PPN][Co(CO)4]
2a
2b
2c
2025
1935
1868
2007
b
1878
2008
1875
2006
1909
1888
1883
a mCO in cm−1, measured in KBr disks. The spectra of NaCo(CO)4
and [PPN][Co(CO)4] (from ref. 38, PPN = (Ph3P)2N+) are listed for
comparison. b Unresolved shoulder.
usually reflects so-called interionic hydrogen bonding between the
ion pairs. The bands at ∼3430 cm−1 also indicate the presence of
intramolecular (concentration-independent) hydrogen bonds. It
has been illustrated by Bockman and Kochi33 that the distortions
of the [Co(CO)4]− anion are extant in crystalline charge-transfer
(CT) salts, and the carbonyl IR bands could provide reliable and
sensitive measures for these distortions. Edgell et al. also indicated
that the extent of the splitting of the T2 band and the intensity of the
A1 mode are measures of the effective dissymmetry of the anion.32
In the IR spectra of all the three salts we have synthesized, the
symmetry-forbidden A1 bands at ∼2005 cm−1 are found, indicating
a distortion of the anion from ideal Td symmetry which could be
caused by the hydrogen bonds, which is in strong contrast to that
of [PPN][Co(CO)4] with an undistorted [Co(CO)4]− in a T2 mode
(Table 1, entries 2–5). Particularly, the compound NaCo(CO)4
(with an anion of C3v symmetry) represents the splitting of the
major T2 carbonyl band (originally at ∼1885 cm−1), while in the
case of 2c, the T2 band splits in another way (Table 1), which is
akin to that previously observed in [NCP]+[Co(CO)4]− (NCP =
4-cyano-N-methylpyridinium) by Bockman and Kochi33 and is
approximately consistent with the Cs symmetry of [Co(CO)4]−,
as established by X-ray crystallography. This represents the most
distorted anion out of the three salts due to the close proximity of
the anion/cation pairs.
Scheme 1 Synthesis of 2.
Miscibility
The miscibilities of the three compounds were determined quali-
tatively in several common solvents. Generally, all the three salts
show similar miscibilities. Most likely due to the ionic nature
of the compounds, they are all well dissolved in more polar
organic solvents such as methanol, acetone, tetrahydrofuran,
dichloromethane, acetonitrile and ethyl acetate, while insolu-
ble in some less polar solvents such as toluene, cyclohexane,
petroleum ether and hexane. None of the compounds is soluble
in water. However, while all the compounds are miscible with
dichloromethane, none of them can dissolve in chloroform (despite
its polarity). This characteristic property of these compounds
would prove useful in their application in convenient and efficient
product separation in catalysis.
NMR studies
1
All the H and 13C NMR chemical shifts of compounds 2 were
consistent with those of their corresponding halide precursors
(1a–1c),34,35 indicating no major change in the chemical structure
of the cationic part of the compounds, in other words, confirming
the cationic part of the compounds to be the expected structure
([CnPy]+). The interionic hydrogen bond also has a detectable
1
effect on the H NMR spectra, i.e. for all three compounds, the
peaks for the 1-H of the pyridinium rings and the 1-H of the N-
alkyls are shifted upfield compared to those of their corresponding
halide precursors,30,35 indicating the close contacts between the two
given hydrogen atoms and the corresponding carbonyl groups of
[Co(CO)4]−, as discussed in the X-ray section. The carbonyl carbon
atoms were still not observed under normal conditions, as has been
indicated before.5 This is probably due to the paramagnetism of
the cobalt center. In some of the 1H NMR spectra, all the peaks
appear as broad single bands, which is also believed to be caused
by the paramagnetism of cobalt.
Infrared studies
In each infrared spectrum of the three compounds, the charac-
teristic CO absorption (T2) band around 1885 cm−1 is found,
representing the presence of the [Co(CO)4]− anion.18,32, yet they
show minor differences from one another. Generally, the CO
absorption band of the pyridinium compounds shifts to lower
wavenumbers compared to that of the corresponding imidazolium
compounds described in the literature,5 and with the lengthening
of the alkyl chain, the CO absorption band shifts to lower
wavenumbers, too. The red shift of the carbonyl stretching band
UV-Vis studies
The UV-Vis absorption spectra for all the three compounds 2a–2c
in the region 200–800 nm were investigated in dichloromethane.
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 4262–4267 | 4263
©

Table 2 UV-Vis absorption of KCo(CO)4 and 2 in dichloromethane
are well within the scale of a typical hydrogen bond. Thus, the
X-ray crystallographic structure indicates that the salt 2c consists
of contact ion pairs that are directionally constrained in the crystal
lattice. This close proximity of the ion pairs (which also exists
in compounds 2a and 2b) sufficiently distorts the tetrahedral
[Co(CO)4]− anion and, as demonstrated above, causes certain
Compound
UV-Vis absorption bands/nm
KCo(CO)4
233, 360(sh)
2a
2b
2c
232, 259(sh), 266(sh)
232, 259(sh), 266(sh)
232, 253(sh), 260(sh), 267(sh)
1
corresponding changes in the IR and H NMR spectra which
suggest their presence. It is thus inferred that the better stability
of the [Co(CO)4]− anion in 2c (and also its analogues, 2a and 2b)
compared to NaCo(CO)4 or KCo(CO)4 is mostly attributed to the
hydrogen-rich environment because of the presence of the cetyl
(methyl, butyl) group.
Data for KCo(CO)4 was also recorded for comparison. The
results are listed in Table 2. It is clear that the spectra of 2
are similar to that of KCo(CO)4. The latter generally shows a
major absorption band at 233 nm, with a shoulder at 360 nm
which is similar to previous reports of other simple [Co(CO)4]−
salts,36–38 assigned as the internal charge-transfer absorption band
(>350 nm). Although not well documented, the only possible
origin of the 233 nm band should be the internal transitions of the
[Co(CO)4]− anion. Compounds 2a–2c exhibit the same band series
with respect to each other, as shown in Table 2. The characteristic
[Co(CO)4]− band at ∼233 nm persists, and a new [253, 260, 267 nm]
shoulder band series has appeared, which is attributed to cyclic
conjugations in the pyridinium rings.39,40 Interestingly, unlike many
analogous [Co(CO)4]− salts,33,36,37,41 no charge transfer absorption
band of 2 is observed in the region beyond 350 nm. In other
words, compounds 2a–2c display no solvatochromism properties
in CH2Cl2, the cations and anions of these compounds dissolved
in CH2Cl2 appear to be solvent-separated ion pairs (SSIPs).33
Other characterizations
In the ESI-MS spectra, only the peaks of the cations and anions
are found, which strongly indicates the structure and purity of the
expected compounds, except that in some cases, especially in the
liquid compound 2b, the cobalt tetracarbonyl anion tends to lose
one or two carbonyls to afford [Co(CO)3]− or [Co(CO)2]−.
The melting points of the two solid compounds 2a and 2c
are given in the Experimental section, both of which are well
below 100 ◦C, thus both salts could be classified as ionic liquids.
And the liquid compound 2b with a Tg value of −81 ◦C is a
room temperature ionic liquid. Because of stability problems,
it is difficult to establish certain routine physical properties of
the three compounds at present, such as density and viscosity.
Attempts to acquire accurate elemental analysis data on such
air sensitive compounds has always been a troublesome task,47,48
however, we have successfully obtained the necessary results for
all the compounds, further establishing our syntheses.
X-Ray studies
After several unsuccessful attempts, X-ray quality crystals of 2c
were obtained by slow diffusion of petroleum ether (60–90 ◦C)
into the dichloromethane solution of 2c while harsh oxygen-free
conditions were maintained. The solid-state structure of 2c reveals
a well-separated ion pair as shown in Fig. 1. The [Co(CO)4]−
anion shows no covalent interactions with the nitrogen center
Catalytic activity
The utilization of [Co(CO)4]− in the alkoxycarbonylation (ring-
opening carbonylation) of epoxides has been previously well
established.49–52 Despite the common use of the Co2(CO)8–
[Lewis base] catalytic system which generates the active species
([Co(CO)4]−) in situ, the direct application of a [Co(CO)4]− con-
taining catalyst in this reaction has been rather rare. Nevertheless,
with respect to the other type of epoxide carbonylation (ring-
expanding carbonylation) reaction, Coates et al. have successfully
developed compounds of the [Lewis acid]+[Co(CO)4]− type as
highly active and selective catalysts.16–19 Although it was estab-
lished that simple non-metallic quaternary [Co(CO)4]− salts are
inactive for the ring-expanding carbonylation of epoxides,19 we
have found in our preliminary test that compound 2b, without
the aid of any additive, smoothly catalyzes the ring-opening
carbonylation of propylene oxide when methanol was used both
as the reactant and the solvent (Scheme 2). Fairly high conversion
(96%) and selectivity (96%) could be obtained, although a
comparatively long reaction time (24 h) was required. Interestingly,
the reaction mixture was fairly stable and did not precipitate after
being stored in air at room temperature for over 24 h. This led
us to investigate the reusability of our catalyst. To our delight,
˚
(Co–N distance = 5.55 A). The pyridinium cation existed as
undistorted cations in the salt. The anionic unit is comprised of
discrete tetrahedral [Co(CO)4]− with a slight distortion from Td
symmetry.42–45 Certain oxygen atoms in the carbonyl groups of
[Co(CO)4]− appear to have interionic hydrogen bonds46 with some
of the hydrogen atoms in the cation. To be exact, for example,
˚
the O1 · · · H21 distance is 2.935 A, the O3 · · · H2B distance is
˚
˚
3.013 A, and the O1 · · · H1A distance is as short as 2.499 A, which
Fig. 1 ORTEP drawing with 20% thermal ellipsoids and numbering
scheme for 2c.
Scheme 2 Alkoxycarbonylation of propylene oxide catalyzed by 2b.
4264 | Dalton Trans., 2007, 4262–4267
This journal is
The Royal Society of Chemistry 2007
©

1H NMR and 13C-NMR spectra were measured on a Varian
INOVA 400 M spectrometer. UV-Vis absorption spectra were
recorded at ambient temperature using an HP 8453 UV-Vis
spectrophotometer. Electrospray ionization mass spectra (ESI-
MS) were recorded on a Waters ZQ4000 spectrometer operating in
ESI mode, on samples dissolved in methanol. Elemental analyses
were carried out on a Vario EL Element Analyzer. Melting
points were determined on an X-4 (Beijing Tech Instrument
Co. Ltd.) melting point apparatus, at comparatively low room
temperature (∼8 ◦C). Tg was determined on a Mettler-Toledo
differential scanning calorimeter (model DSC 822e) at a scan rate
Table 3 Catalytic run of 2b in the alkoxycarbonylation of propylene
oxidea
Runb
Conversionc (%)
Selectivityc (%)
Yieldd (%)
1
96
88
90
89
77
96
95
95
94
93
92
84
84
84
72
2e
3e
4e
5e
a Reaction at 60 ◦C, 8.0 MPa of CO, 24 h in methanol (5 equiv. to propylene
oxide) and Substrate/Catalyst (mol) = 25. b In the next catalytic run, the
reaction mixture was directly charged with another portion of substrate
and solvent without any further treatment. c Determined by GC using
an SE-30 column (0.32 mm × 41 m). d Yield = conversion × selectivity.
e Overall results for all catalytic runs added up (see note b).
◦
of 10 C min−1. The crystal structure was measured on a Bruker
SMART APEX II CCD diffractometer.
Preparation of 1
the catalytic system could be reused 4 times, with little loss of
selectivity and only a minor drop in conversion (Table 3). It is
worth noting that even in the 5th catalytic run, almost quantitative
conversion could still be obtained if the reaction time was further
increased. The good reusability of this catalytic system could
be mostly attributed to the good stability of the catalyst. This
represents a successful and promising example of a fairly stable
catalyst that directly immobilizes the versatile [Co(CO)4]− species.
Subsequently, compounds 2a and 2c have also been confirmed for
their comparative catalytic activities.
The precursors, alkylpyridinium 1a, 1b were prepared as pre-
viously published,54,55 from pyridine and methyl iodide for 1a,
pyridine and n-butyl chloride for 1b, as the starting materials,
respectively, and 1c is commercially available.
Preparation of 2a
A tetrahydrofuran solution of KCo(CO)4 was prepared according
to a previously reported method,56,57 except that KOH was used
instead of NaOH. When the reaction was complete after 3 h, the
filtrate of the reaction mixture was added to a 60 mL Schlenk tube
under an Ar atmosphere followed by the removal of the solvent
in vacuo, to afford the product as a white solid (0.99 g, 4.71 mmol,
94%). Subsequently, 10 mL of degassed water was added and
the KCo(CO)4 was redissolved, which was then injected with
1.09 g (4.95 mmol, 1.05equiv.) of C1PyI (1a) dissolved in 5 mL of
degassed water and stirred. The product soon precipitated, which
was immediately dissolved by another portion of CH2Cl2 (20 mL).
After being stirred for another 20 min, the reaction mixture was
left to stand for phase-separation. The water phase was removed
with a syringe, and the remaining organic phase was washed with
degassed water (3 × 20 mL) before being dried with MgSO4 over
night. The mixture was then filtered under an Ar atmosphere,
and the solvent was removed in vacuo, recrystallization from
CH2Cl2–petroleum ether (60–90 ◦C) afforded the product 2a
as orange powder, which was stored under Ar in the dark
Conclusions
The water–organic biphasic strategy has been found to be a pre-
ferred way of synthesizing A[Co(CO)4] (A = N-alkylpyridinium)
type organometallic ionic liquids of required purity. Through
this strategy, new pyridinium based ionic liquids 2a–2c have
been successfully synthesized and characterized using a variety
of techniques. Notably, 2c is of remarkably good air stability com-
pared to formerly reported analogues, representing an affirmative
case of stabilizing the highly air sensitive cobalt tetracarbonyl
anion. We are of the opinion that interionic hydrogen bonds are
generally responsible for the effective stabilization of the anion.
These new breakthroughs should be of considerable importance to
future investigations into these novel and interesting compounds,
namely, metal carbonyl ionic liquids. These compounds, without
the presence of organic ligands, have been shown to be efficient
and reusable catalysts for the alkoxycarbonylation of epoxides
and are recognized as a veritable “ionic liquid catalyst”. Further
investigations on these organometallic ionic liquids and their
utilization are now underway.
◦
(1.02 g, 82%); mp 16–17 C (Found: C, 45.17; H, 3.08; N, 5.25.
C10H8NO4Co requires C, 45.31; H, 3.04; N, 5.28%); selected
1
mmax/cm−1 (KBr) 1878vs [[Co(CO)4]−]; H NMR(acetone-d6): dH
(CD3COCD3 400 MHz) 9.131 [2H, d, NCHCH], 8.728 [1H, t,
CHCHCH], 8.270 [2H, t, NCHCHCH], 4.651 [3H, s, NCH3];
dC (CD3COCD3 400 MHz) 146.285 [s, CHCHCH], 146.110 [s,
NCHCH], 128.774 [s, NCHCHCH], 48.908 [s, NCH3]; ESI-MS
positive ion: m/z 94 ([C1Py]+); ESI-MS negative ion: m/z 171
([Co(CO)4]−), 143 ([Co(CO)3]−).
Experimental
General
All the organometallic manipulations were carried out under an Ar
atmosphere using standard Schlenk techniques. Unless otherwise
noted, all the reagents were of analytical grade and were used
as received. Tetrahydrofuran (THF), dichloromethane, petroleum
ether (60–90 ◦C) and distilled water were purged with argon prior
to use to eliminate the dissolved oxygen. Co2(CO)8 was prepared
through a high pressure procedure according to the literature.53 IR
spectra were recorded on a Bruker IFS 120HR spectrophotometer.
Preparation of 2b
The reaction procedure is similar to that described above for
2a. C4PyBr (1b) was used for the metathesis with KCo(CO)4:
crimson viscous oily liquid (1.22 g, 84%); Tg − 81 ◦C (Found: C,
50.24; H, 4.39; N, 4.91. C13H14NO4Co requires C, 50.83; H, 4.59;
N, 4.56%); selected mmax/cm−1 (liquid film) 1875vs ([Co(CO)4]−);
dH (CD3COCD3 400 MHz) 9.053 [2H, br s, NCHCH], 8.640
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 4262–4267 | 4265
©

Table 5 Data collection and structure refinement for 2c
[1H, br s, CHCHCH], 8.175 [2H, br s, NCHCHCH], 4.478 [2H,
br s, NCH2CH2CH2CH3], 2.040 [2H, br s, NCH2CH2CH2CH3],
1.377 [2H, br s, NCH2CH2CH2CH3], 0.895 [3H, br s, NCH2-
CH2CH2CH3]; dC (CD3COCD3 400 MHz) 145.660 [s, CHCHCH],
144.546 [s, NCHCH], 128.438 [s, NCHCHCH], 61.826 [s,
NCH2CH2CH2CH3], 33.014 [s, NCH2CH2CH2CH3], 19.043 [s,
NCH2CH2CH2CH3], 12.786 [s, NCH2CH2CH2CH3]; ESI-MS
positive ion: m/z 135 ([C4Py]+); ESI-MS negative ion: m/z 171
([Co(CO)4]−).
Molecular formula
Mr
C25H38CoNO4
475.49
P21/c
Monoclinic
8.1404(5)
7.1357(4)
46.865(3)
90.824(1)
2722.0(3)
4
291
1.160
Space group
Crystal system
˚
a/A
˚
b/A
˚
c/A
b/◦
3
˚
V/A
Z
T/K
Dc/g cm−3
Preparation of 2c
l/mm−1
0.657
F(000)
1016
The reaction procedure is similar to that described above for 2a.
C16PyCl (1c) was used for the metathesis with KCo(CO)4: golden
solid (1.66 g, 74%); mp 40–41 C (Found: C, 62.75; H, 7.73; N,
Crystal size/mm
0.32 × 0.25 × 0.09
h-Range for data collection/◦
Index ranges, hkl
No. of reflections collected
No. of independent reflections (Rint
No. of reflections with I > 2r(I)
2.50–27.50
◦
−10 to 10; −7 to 9; −60 to 49
16573
6241
3171
0.71073
2.99. C25H38NO4Co requires C, 63.15; H, 8.05; N, 2.95%); selected
mmax/cm−1 (KBr) 1909, 1888, 1864 ([Co(CO)4]−); dH (CD3COCD3
400 MHz) 9.204 [2H, d, NCHCH], 8.749 [1H, t, CHCHCH], 8.294
[2H, t, NCHCHCH], 4.863 [2H, t, NCH2CH2(CH2)2(CH2)11CH3],
2.149 [2H, quintet, NCH2CH2(CH2)2(CH2)11CH3], 1.403 [4H,
quintet, NCH2CH2(CH2)2(CH2)11CH3], 1.259 [22H, m, NCH2-
CH2(CH2)2(CH2)11CH3], 0.858 [3H, t, NCH2CH2(CH2)2(CH2)11-
CH3]; dC (CD3COCD3 400 MHz) 146.468 [s, NCHCH],
145.438 [s, CHCHCH], 129.186 [s, NCHCHCH], 62.680 [s,
NCH2CH2CH2(CH2)10CH2CH2CH3], 32.350 [s, NCH2CH2CH2-
(CH2)10CH2CH2CH3], 31.877 [NCH2CH2CH2(CH2)10CH2CH2-
CH3], 30.183–29.023 [m, NCH2CH2CH2(CH2)10CH2CH2CH3],
26.475 [s, NCH2CH2CH2(CH2)10CH2CH2CH3], 23.049 [s, NCH2-
CH2CH2(CH2)10CH2CH2CH3], 14.098 [s, NCH2CH2CH2(CH2)10-
CH2CH2CH3]; ESI-MS positive ion: m/z 304 ([C16Py]+); ESI-MS
negative ion: m/z 171 ([Co(CO)4]−).
)
˚
k(Mo-Ka)/A
Absorption correction
Max., min. transmission
Refinement method
Data, restrains, parameters
Goodness-of-fit on F2
Final R-indices [I > 2r(I)]a
R indices (all data)a
Multi-scan
0.8183, 0.9420
Full-matrix least squares on F2
6241, 0, 281
1.010
R1 = 0.0441; wR2 = 0.1055
R1 = 0.0994; wR2 = 0.1303
ꢀ
ꢀ
ꢀ
ꢀ
a R1 = ꢀFo| − |Fcꢀ/ |Fo|; wR2 = { [w(Fo − Fc2)2]/ [w(Fo2)2]}
.
2
1/2
Acknowledgements
The authors are grateful to the National Natural Science Foun-
dation of China (20533080, 20625308) and Chinese Academy of
Sciences for financial support of this work.
Notes and references
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The Royal Society of Chemistry 2007
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©