Synthesis and characterisation of organometallic imidazolium compounds that include a new organometallic ionic liquid

Article abstract of DOI:10.1039/b308252k

New imidazolium salts, 1-(prop-2-ynyl)-3-vinyl-3H-imidazol-1-ium bromide, 1a, the tetraphenylborate, 1b, and hexafluorophosphate, 1c, salts of 1a and 3-allyl-1-(prop-2-ynyl)-3H-imidazol-1-ium bromide, 2a, containing alkene and alkyne groups for derivatisation were prepared from commercially available starting materials and fully characterised. New organometallic imidazolium salts, [{μ₂-HCCCH₂N=C(H)N(CH=CH₂) CH=CH}Co₂(CO)₆]X [X^- = BF₄^-, B(C₆H₅)₄^- or PF₆^-], 3a, 3b or 3c, and [{μ₂-HCCCH₂N=C(H)N(CH₂CH=CH₂) CH=CH}Co₂(CO)₆]BF₄, 4a, and a new organometallic ionic liquid, [{μ₂-HCCCH₂ N=C(H)N(CH₂CH=CH₂)CH=CH}Co₂(CO)₆] PF_6, 4b, were isolated by reacting 1a-c or 2a with Co₂ (CO)₈. The compound 4b, the first ionic liquid bearing an organometallic moiety covalently attached to the cation, melts reversibly at 75-77°C without decomposition. The imidazolium protons in 1b and 3b are shielded in the ¹H NMR as a result of π-interaction with the phenyl rings of the tetraphenyl-borate anion. The cation-anion contacts (C-H ... π ～ 2.6 A) observed in the molecular structure of 3b in the solid state are also maintained in solution, as evidenced in NOE NMR experiments. The molecular structures of 3b and 3c show an alkyne unit bonded to a Co₂(CO)₆ fragment with the C≡C bond perpendicular to the Co-Co bond.

Full text of DOI:10.1039/b308252k

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Synthesis and characterisation of organometallic imidazolium
compounds that include a new organometallic ionic liquid†
Herwig Schottenberger,*a Klaus Wurst,a Ulrike E. I. Horvath,b Stephanie Cronje,*b
Josef Lukasser,a Johann Polin,a Jean M. McKenzieb and Helgard G. Raubenheimer*b
a Institut für Allgemeine, Anorganische und Theoretische Chemie, Leopold Franzens Universität,
Innrain 52a, A-6020 Innsbruck, Austria. E-mail: herwig.schottenberger@uibk.ac.at;
Fax: ϩ43 512 507 2934; Tel: ϩ43 512 507 5120
b Department of Chemistry, University of Stellenbosch, Private Bag X1, Matieland, 7602,
Stellenbosch, South Africa. E-mail: scron@sun.ac.za; Fax: ϩ27 21 808 3849;
Tel: ϩ27 21 808 2180
Received 18th July 2003, Accepted 9th September 2003
First published as an Advance Article on the web 22nd September 2003
New imidazolium salts, 1-(prop-2-ynyl)-3-vinyl-3H-imidazol-1-ium bromide, 1a, the tetraphenylborate, 1b, and
hexafluorophosphate, 1c, salts of 1a and 3-allyl-1-(prop-2-ynyl)-3H-imidazol-1-ium bromide, 2a, containing alkene
and alkyne groups for derivatisation were prepared from commercially available starting materials and fully
characterised. New organometallic imidazolium salts, [{µ -HCCCH N᎐C(H)N(CH᎐CH )CH᎐CH}Co (CO) ]X
᎐
᎐
᎐
2
2
2
2
6
[XϪ = BF4 , B(C6H5)4Ϫ or PF ], 3a, 3b or 3c, and [{µ -HCCCH N᎐C(H)N(CH CH᎐CH )CH᎐CH}Co (CO) ]BF ,
Ϫ
Ϫ
᎐
᎐
᎐
6
2
2
2
2
2
6
4
4a, and a new organometallic ionic liquid, [{µ -HCCCH N᎐C(H)N(CH CH᎐CH )CH᎐CH}Co (CO) ]PF , 4b, were
᎐
᎐
᎐
2
2
2
2
2
6
6
isolated by reacting 1a–c or 2a with Co2(CO)8. The compound 4b, the first ionic liquid bearing an organometallic
moiety covalently attached to the cation, melts reversibly at 75–77 ЊC without decomposition. The imidazolium
protons in 1b and 3b are shielded in the 1H NMR as a result of π-interaction with the phenyl rings of the tetraphenyl-
borate anion. The cation–anion contacts (C–H ؒ ؒ ؒ π ∼ 2.6 Å) observed in the molecular structure of 3b in the solid
state are also maintained in solution, as evidenced in NOE NMR experiments. The molecular structures of 3b and 3c
᎐
show an alkyne unit bonded to a Co (CO) fragment with the C᎐C bond perpendicular to the Co–Co bond.
᎐
2
6
ment of many more ionic liquids. This is demonstrated by an
ionic liquid derived from the antifungal drug miconazole, which
exhibits lyotropic liquid crystalline behaviour and induces the
gelation of benzene.7
Introduction
The replacement of volatile organic compounds as solvents
in organic synthetic processes by recyclable environmentally
friendly ionic liquids1 together with their reaction modifying
effects (activity and selectivity) and the possibility of multi-
phase reaction procedures with simple product separation and
homogeneous catalyst recovery have rendered this new class of
solvents extremely popular.2,3
The protection of alkynes by reaction with Co2(CO)8 to form
(µ-alkyne)Co2(CO)6 complexes, the generation of [2 ϩ 2 ϩ 2]-
cycloadditions via an intramolecular Heck reaction, the
formation of cyclopentenones with an alkyne, alkene and CO
(Pauson–Khand reaction) and the stereo-controlled C–C bond
formation using propargyl cations with α-carbons activated to
nucleophilic substitution through stabilisation of the inter-
mediate carbocation (Nicholas reaction), are well established
in synthetic procedures8–18 and can be used to extend the
derivatisation of suitably N-substituted imidazolium salts.
Several (µ-alkyne)Co2(CO)6 compounds have been structurally
studied.9–18 Organometallic imidazolium salts which act as
A myriad of homogeneously catalysed reactions have been
studied and promise clean synthetic methodologies for the
future.1 Generally, salts of organic cations e.g. tetraalkyl-
ammonium, tetraalkylphosphonium, N-alkylpyridinium, 1,3-
dialkylimidazolium and trialkylsulfonium cations, are room-
temperature ionic liquids.1 Meticulous selection of the cations
and anions in the ionic liquid can tailor the required solvent
properties of the ionic liquid to the requirements of the target
reactions.1–3 The derivatisation of the cations and anions places
an infinite set of designer solvents at the disposal of the syn-
thetic chemist.4 The functionalisation of the N-substituents in
the imidazolium based ionic liquids with exocyclic alkene and
alkyne groups creates many new opportunities for the extension
of the pool of designer solvents, as well as functionality-
tailored solute targets, e.g. 1-imidazolethynylphosphines.5 By
grafting the substrate benzaldehyde onto an ionic liquid
through the N-substituent in the imidazolium salt, Fraga-
Dubreuil and Bazureau have been able to perform Knoevenagel
and 1,3-dipolar cycloaddition reactions on the substrate in a
“solvent free environment”.6 Increased possibilities for func-
tionalisation of the N-substituents in imidazolium cations
would enable the use of bioactive molecules for the develop-
1
anion receptors and Lewis acid catalysts are known. H NMR
studies of ferrocenyl imidazolium salts in CDCl3 have indicated
the existence of C–H ؒ ؒ ؒ XϪ hydrogen bonding at NC(H)N.19
Organic ligands with delocalised π-systems, joined by metal
centres to form organometallic polymers, are suitable pre-
cursors for solid state materials of technological interest.18 The
synthesis and characterisation of metallopolymers, consisting
of poly(phenylene diacetylenes) that contain Pt and Co
coordinated to the triple bonds of the diacetylene moieties,
and their conversion upon thermal treatment as thin films to
conductive, metal-doped, hetero-glassy carbon (HGC), has
important implications for fuel cell electrode development.20
Organometallic ionic liquids are rare21 and the first cata-
lytically active example [bmim][Co(CO)4] (bmim = 1-butyl-3-
methylimidazolium) was recently described.22 Analysis of
[Rh(CO)2I2][bmim] by ESI-MS combined with quadropole ion
trap methods showed the Monsanto catalyst parent anion and
fragments indicating sequential CO ligand loss.23
† This paper is based on work presented at OMCOS 8 held at Santa
Barbara, USA, 6–10 August 1995. Electronic supplementary inform-
ation (ESI) available: Table of ionic liquids and melting points. See
http://www.rsc.org/suppdata/dt/b3/b308252k/
Other ionic liquids with transition metal containing anions
[bmim][AuCl4], [emim][AuCl4]24 (emim = 1-ethyl-3-methylimid-
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
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azolium), [BMTz][AuCl4]25 (BMTz
thiazolium), [dmim][CoCl4] (dmim
=
3-butyl-4-methyl-
1-dodecyl-3-methyl-
where necessary, the products 3a–c, 4a and 4b were extracted
from the aqueous phase with CH2Cl2. The cobalt compounds
are stable in air and deoxygenated water and decompose slowly
in CH2Cl2 – quite unusual for (µ-alkyne)Co2(CO)6-type com-
pounds.10,11,13–16,18
=
imidazolium), [omim][CoCl4] (omim = 1-octadecyl-3-methyl-
imidazolium), [dmim]2[NiCl4] and [omim]2[NiCl4]26 have been
synthesised and characterised, and the latter Ni- and Co-
containing compounds display liquid crystal behaviour over
extended temperature ranges. Addition of 1,1Ј-bis(diphenyl-
phosphino)cobaltocenium hexafluorophosphate to [Rh(CO)2-
(acac)] in [bimim][PF6] improved the hydroformylation of
1-octene substantially and prevented leaching of the catalyst
into the substrate.27
The molecular ion, anion and fragments thereof of 1b and
the molecular ion and imidazolium fragment of 2a were
observed in the electron impact mass spectra of these com-
pounds, while only the imidazolium cations were present in the
spectra of 1a and 1c. The cations of 3a–c, 4a and 4b were
observed in the FAB mass spectra of these compounds.
The organic imidazolium salts 1c and 2a melt at temperatures
below 100 ЊC and are ionic liquids, whereas 1a and 1b melt at
temperatures above 100 ЊC and do not meet this requirement.
Compound 4b melts reversibly at 75–77 ЊC and thus qualifies as
an organometallic ionic liquid that is not easy to crystallise. The
other organometallic imidazolium salts 3a, 3b, 3c and 4a all
decompose before melting.
We now report the straight forward synthesis of new imid-
᎐
azolium salts, [HC᎐CCH N᎐C(H)N(CH᎐CH )CH᎐CH]X
᎐
᎐
᎐
᎐
2
Ϫ
2
(XϪ
=
BrϪ,
B(C6H5)4
or
PF6Ϫ),
1a–c
and
᎐
[HC᎐CCH N᎐C(H)N(CH CH᎐CH )CH᎐CH]Br, 2a, with two
᎐
᎐
᎐
᎐
2
2
2
functional groups available for derivatisation, the synthesis of
the new organometallic imidazolium salts, [{µ2-HCCCH2-
Ϫ
N᎐C(H)N(CH᎐CH )CH᎐CH}Co (CO) ]X [XϪ
=
BF4
,
᎐
᎐
or
᎐
Molecules of the type (µ-HCCR)Co2(CO)6 may possess at
most, Cs symmetry and all six terminal C–O stretching modes
are IR active.12,14,28 As in reported results, three strong C–O
2
2
6
Ϫ
B(C6H5)4
PF6Ϫ],
3a–c
and
[{µ2-HCCCH2-
N᎐C(H)N(CH CH᎐CH )CH᎐CH}Co (CO) ]BF , 4a and
a
᎐
᎐
᎐
2
2
2
6
4
frequencies [ν1(a1) at ca. 2092 cmϪ1, ν4(b1) at ca. 2052 cmϪ1
,
new
organometallic
ionic
liquid,
[{µ2-HCCCH2-
9–18
ν2(a1) at ca. 2021 cmϪ1
]
are observed in the IR spectra of
N᎐C(H)N(CH CH᎐CH )CH᎐CH}Co (CO) ]PF , 4b (Scheme 1).‡
᎐
᎐
᎐
2
2
2
6
6
3a-c, 4a and 4b (ca. 2110, 2060 and 2020 cmϪ1). The C–O fre-
quencies that are not observed [ν6(b2) at ca. 2029s cmϪ1, ν5(b1)
at ca. 2011w cmϪ1 and ν3(a2) at ca. 2008vw cmϪ1] are obscured
by broad neighbouring bands [ν6(b2)] or extremely weak.
The H–C stretch in the infrared spectrum of the imidazolium
salts are observed at ca. 3200 cmϪ1 for the H–C᎐C unit and at
᎐
᎐
ca. 3100 cmϪ1 for the H–C᎐C unit. Upon coordination of the
᎐
᎐
alkyne to Co (CO) , the H–C stretch for the H–C᎐C unit moves
᎐
2
6
to lower wavenumbers (ca. 3150 cmϪ1). An even larger shift
᎐
to lower wavenumbers is observed in the C᎐C stretching
᎐
frequencies: from ca. 2120 to ca. 1560 cmϪ1. Similar changes in
᎐
the H–C and C᎐C stretching frequencies were observed for
᎐
other alkyne ligands after coordination to Co2(CO)6.9,10,14,18
1
When comparing the H NMR spectrum of 1b to those of
1a and 1c, shielding of the NC(H)N proton (4 ppm) and
the NCH᎐CHN protons (1 ppm) of the imidazolium ring
᎐
are obvious. This can be ascribed to the influence of the
Ϫ
B(C6H5)4 anion which maintains a contact ion pair structure
in solution and exerts CH ؒ ؒ ؒ π interation on the protons of
the imidazolium ring via its phenyl rings. Similar results were
reported for 1-butyl-3-methyl-2,3-dihydro-1H-imidazolium
tetraphenylborate.29,30
᎐
Scheme 1 Reagents and conditions: i, HC᎐CCH2Br; ii, NH4B(C6H5)4
᎐
for 1b, NH4PF6 for 1c; iii, Co2(CO)8; iv, NH4BF4 for 4a and NH4PF6 for
4b.‡
The strongest evidence for coordination of the alkynes to
Co2(CO)6 is the downfield shift (from ca. δ 3 to ca. δ 6.4) of the
terminal alkyne protons in the H NMR spectra. The other
1
largest change in chemical shift (0.5 ppm downfield) is observed
for the CH2 group of the alkyne substituent. These changes
are also reflected in the 13C NMR spectra of 3a–c, 4a and 4b
where the terminal alkyne carbon experiences a deshielding
effect (8 ppm) and the CH2 carbons of the alkyne substituent
experience a similar downfield shift (10 ppm) upon co-
ordination. These changes in chemical shift reflect the reduction
in triple bond character of the coordinated alkyne.
Results and discussion
Synthesis and characterisation
The treatment of 1-vinyl-1H-imidazole or 1-allyl-1H-imidazole
with a commercially available stock solution of BrCH C᎐CH
᎐
᎐
2
in toluene produced 1a and 2a. Compound 2a has a very low
solubility in organic solvents but both 1a and 2a are soluble in
water. The addition of NH4BF4 or NH4B(C6H5)4 to solutions
of 1a in water, precipitated 1b and 1c thus providing an efficient
process for product purification. The difference in solubility of
the compounds was also exploited in the purification of the new
orange organometallic imidazolium salts 3a, 3b, 3c, 4a and 4b
formed by reacting Co2(CO)8 with equimolar amounts of 1a–c,
or 2a in CH2Cl2 and counteranion exchange (when the anion
is BrϪ) with NH4BF4 or NH4PF6. Unreacted Co2(CO)8 was
extracted with diethyl ether from the crude product mixture
suspended in water, while the organometallic imidazolium salt
remained in the aqueous phase. After counteranion exchange
1
In the H NMR spectrum of 3b a slight downfield shift of
0.5 ppm is observed for the imidazolium NC(H)N proton when
compared to its shift in 1b but this value is still significantly
upfield (4 ppm) from the NC(H)N protons in 3a, 3c, 4a and
4b. The chemical shifts of the NCH᎐CHN protons of the
᎐
imidazolium ring in 3b are also shifted slightly upfield (1 ppm)
when compared to those in 3a, 3c, 4a and 4b. In the molecular
structure of 3b (vide infra) the proton in question is seen to be
lying in close proximity to one of the phenyl rings of the
Ϫ
B(C6H5)4 anion when in the solid state [distance H(4) to
B-phenyl C(21)–C(26) centroid = 2.58 Å]. By carrying out 1D
NOE experiments it was shown that this is also the situation in
solution as excitation of selected protons [H(5), H(6) and H(7)]
on the cation of 3b resulted in enhancements of phenyl proton
‡ The numbering of the ligands in Scheme 1, Fig. 1 and Fig. 2 is
arbitrary.
D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
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Table 1 Selected bond lengths (Å) and angles (Њ) of complexes 3b and 3c
3b
3b (B)
3c
3b
39.28(14)
3b (B)
3c
Co(1)–Co(2)
Co(1)–C(1)
Co(1)–C(2)
Co(2)–C(1)
Co(2)–C(2)
Co(1)–C(10)
Co(1)–C(20)
Co(1)–C(30)
Co(2)–C(40)
Co(2)–C(50)
Co(2)–C(60)
C–O (av.)
N(1)–C(4)
N(1)–C(6)
N(1)–C(3)
N(2)–C(4)
N(2)–C(5)
N(2)–C(7)
N(2)–C(7A)
C(1)–C(2)
2.4726(7)
1.949(4)
1.957(3)
1.948(4)
1.937(3)
1.789(4)
1.806(4)
1.824(4)
1.796(4)
1.803(6)
1.790(6)
1.129(5)
1.319(4)
1.378(4)
1.472(5)
1.332(5)
1.380(4)
1.420(5)
2.4562(7)
1.952(4)
1.955(4)
1.950(4)
1.951(3)
1.747(5)
1.813(4)
1.809(5)
1.790(4)
1.807(4)
1.817(4)
1.137(5)
1.325(4)
1.377(5)
1.471(5)
1.315(5)
1.374(5)
1.446(5)
2.4644(9)
1.963(3)
1.957(3)
1.947(3)
1.960(3)
1.792(4)
1.824(4)
1.815(4)
1.791(4)
1.820(4)
1.822(4)
1.131(4)
1.324(4)
1.374(4)
1.472(3)
1.325(4)
1.362(4)
1.435(6)
1.534(18)
1.334(4)
1.488(4)
1.331(4)
1.280(8)
1.23(2)
C(1)–Co(1)–C(2)
C(1)–Co(2)–C(2)
Co(1)–C(1)–Co(2)
Co(1)–C(2)–Co(2)
Co(2)–Co(1)–C(10)
C(1)–Co(1)–C(20)
C(2)–Co(1)–C(30)
Co(1)–Co(2)–C(40)
C(1)–Co(2)–C(50)
C(2)–Co(2)–C(60)
Co–C–O (av.)
H(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(4)–N(1)–C(6)
C(4)–N(2)–C(5)
N(1)–C(4)–N(2)
C(6)–C(5)–N(2)
C(5)–C(6)–N(1)
C(8)–C(7)–N(2)
C(8A)–C(7A)–N(2)
39.54(14)
39.59(15)
78.02(14)
77.91(13)
149.63(17)
143.65(17)
139.25(17)
145.61(13)
138.19(16)
144.65(17)
177.2(4)
142(2)
141.0(3)
107.9(3)
108.3(3)
109.2(3)
107.3(3)
107.2(3)
122.8(4)
39.80(12)
39.94(12)
78.14(12)
77.97(10)
149.80(13)
140.62(14)
141.27(14)
148.67(10)
144.34(14)
138.73(15)
178.2(4)
143(2)
140.5(3)
107.7(2)
108.4(2)
108.8(3)
107.5(3)
107.6(3)
122.0(6)
39.50(14)
78.78(15)
78.83(13)
150.66(12)
141.56(17)
140.20(16)
150.64(14)
141.2(2)
139.9(2)
178.2(5)
143(2)
140.8(3)
107.9(3)
108.0(3)
109.0(3)
107.1(3)
108.0(3)
124.9(4)
1.313(5)
1.492(5)
1.328(5)
1.284(6)
1.321(5)
1.496(5)
1.335(6)
1.254(6)
111.5(18)
C(2)–C(3)
C(5)–C(6)
C(7)–C(8)
C(7A)–C(8A)
signals of the anion. Thus, the cation and anion of 3b as in 1b
remain close to each other even in solution and the shielding
effect of one of the phenyl rings on the NC(H)C proton is
cleary seen in the 1H NMR spectrum.
All other signals are consistent with the proposed structures
and do not experience large changes when compared to the
signals of the uncoordinated imidazolium salts. The imid-
azolium carbons and alkyne carbons were unambigiously
assigned using Gradient Heteronuclear Single Quantum
Coherence (GHSQC) experiments and Gradient Heteronuclear
Multiple Quantum Coherence (GHMQC) experiments.
One broad signal at δ 199 is observed for the carbonyl
carbons suggesting that they are rapidly exchanging. The NMR
data are typical of (µ-HCCR)Co2(CO)6 compounds.9–11,13,14,18
Ϫ
The septet for the P atom in the PF6 ions is observed at
δ Ϫ144 (1JPF = 711 Hz) in the 31P NMR spectra of 1c, 3c and 4b.
1
The ipso (quartet at δ 164, JBC = 49 Hz) and meta (quartet at
3
δ 126, JBC = 3 Hz) phenyl carbon atoms of the tetraphenyl-
borate anion in 1b and 3b experience boron coupling.
Molecular structures
The molecular structures of 3b and 3c are shown in Fig. 1 and
Fig. 2. Selected bond parameters are listed in Table 1. The unit
cell of compound 3b contains two cation and anion pairs in the
asymetric unit. The cations consists of a ‘Co2C2’ core with
pseudo-tetrahedral geometry. The C(1)–C(2) alkyne bonds are
arranged perpendicular to the Co(1)–Co(2) bonds. The co-
ordination geometry about the Co atoms is pseudo-octahedral.
The Co(1)–Co(2) bond length found in 3b and 3c lies within the
range, 2.46–2.48 Å [not influenced by the groups attached to the
C(1)–C(2) unit] observed for other dicobalt systems that are
bridged by perpendicular alkyne ligands,10,13–16,18 but is shorter
than the value reported for the Co–Co distance in Co2(CO)8.14
As widely reported, coordination of the ethynyl group C(1)–
C(2) to the Co2(CO)6 unit leads to an expansion of the triple
Fig. 1 Molecular structure of 3b showing only one of the two ion
pairs per asymmetric unit and the numbering scheme. Ellipsoids are
shown at 30% probability level.‡
bond to 1.313(5) and 1.321(5) Å in 3b and 1.334(4) Å in 3c. This
᎐
is consistent with the loss of C᎐C bond character as a result
᎐
of delocalisation of the electron density onto the Co2(CO)6
unit. The same bond distance in similar compounds ranges
from 1.33 to 1.36 Å.13–16,18 Deviation from sp-hybridisation at
C(1) and C(2) is evident in the pivotal angles H(1)–C(1)–C(2)
and C(1)–C(2)–C(3), similar values have been reported.13,14,18
The four Co–C(alkyne) distances in 3b and 3c are similar to
Fig. 2 Molecular structure of 3c showing the numbering scheme.
Ellipsoids are shown at 40% probability level.‡
D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
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reported values.13,16–18 These distances do not show the assym-
metric pattern observed in [{Co2(CO)6}2(HC2C6H4C2H)]14
cation. Melting points were determined on a Kofler hot-stage
or an Electrothermal 9100 apparatus and are uncorrected.
Mass spectra were recorded on an AMD 604, Varian CH-7 (EI,
70eV) or a MAT 95 (FAB in glycerin) instrument, the infrared
spectra on a Perkin-Elmer 1600 Series FTIR or a Nicolet
510FT-IR spectrometer and NMR spectra on a Bruker AC 200,
Varian 300 FT or INOVA 600 MHz spectrometer (1H NMR at
200/300/600 MHz, 13C{1H} NMR at 75/150 MHz and 31P{1H}
NMR at 121/243 MHz, δ reported relative to the solvent
resonance, TMS or external reference 85% H3PO4). Elemental
analyses were carried out by the Analytical Department of
Lenzing AG, A-4840 Lenzing, Austria or the Department
of Chemistry, University of Cape Town, South Africa.
[{Co2(CO)6]2{(CH3)3SiC2C6H4C2H)]13
and
[{Co2(CO)6}-
{(CH3)3SiCCSi[CCSi(CH3)3]3}]15 in which the nature of the
substituents on the ethynyl group are reflected in the Co–C
bond lengths.
The C᎐N bond is more delocalised than the C᎐C bond in the
᎐
᎐
imdazolium ring when compared to the neutral imidazole
system,31 whereas the single and double bonds of the N–C᎐N
᎐
part are in the range of 1.349 and 1.313 Å and the C᎐C double
᎐
bond is lengthened to 1.360 Å. The vinyl group in 3b and in 3c
is nearly coplanar to the imidazolium plane, whereas the
ethenyl group is twisted out of the plane with torsion angles
N1–C3–C2–C4 of Ϫ61.6(6)Њ and N1B–C3B–C2B–C4B of
68.6(6)Њ for 3b and 42.9(5)Њ for 3c. Conformational disorder was
observed for the vinyl substituent in 3c (ratio 3 : 1), but the
bond distance of the ethenyl group [C(7)–C(8)] in 3b and 3c is
in the normal range of a double bond.31 The angles in the ring
vary between 107.1(3) and 109.0(3)Њ. The bond parameters for
the imidazolium ring are similar to reported values.32,33
᎐
Preparation of [HC᎐CCH N᎐C(H)N(CH᎐CH )CH᎐CH]Br,
᎐
᎐
᎐
᎐
2
2
3
᎐
1a. Dichloromethane (30 cm ), 80% HC᎐CCH Br in toluene
᎐
2
(16.9 cm3, 151.7 mmol) and 1-vinyl-1H-imidazole (10.0 cm3,
110.4 mmol) were stirred for 2.5 h at room temperature. The
mixture was reduced to dryness in vacuo. After the addition of
diethyl ether (40 cm3) to the residue, trituration, filtration and
thorough washing with diethyl ether (3 × 50 cm3) the beige
product (15.34 g, 65%) was dried in vacuo, mp 157–158 ЊC
(Found: C, 44.90; H, 3.95; N, 13.07, C8H9BrN2 requires C,
Bond angles and lengths of the tetrahedral tetraphenylborate
anion in 3b agree with values described for 1-butyl-3-methyl-
2,3-dihydro-1H-imidazolium tetraphenylborate.29 The average
B–C bond distance is 1.651(5) Å.
45.09; H, 4.26; N, 13.15%); selected νmax/cmϪ1 (C4Cl6, NaCl)
3154w [H–C᎐CCH N], 3077w, 3047w (H–C᎐C), 2115m
(C᎐C); δ (CD3CN, 600 MHz) 9.53 [1H, s, NCHN], 7.80 [1H,
t, J(Z) = 1.9 Hz, NCH᎐CHNCH᎐CH ], 7.64 [1H, t, J(Z) =
Ϫ
Similarly, the bond parameters of the PF6 anion in 3c are
᎐
᎐
᎐
2
comparable to other reported examples.33 The average P–F
bond distance is 1.586(2) Å and the F–P–F(cis) and F–P–F-
(trans) angles deviate only slightly from 90 and 180Њ.
᎐
᎐
H
3
3
᎐
᎐
᎐
2
3
1.9 Hz, NCH᎐CHNCH᎐CH ], 7.25 [1H, dd, J(E) = 15.5 Hz,
᎐
2
3J(Z) = 8.6 Hz, NCH᎐CHNCH᎐CH ], 5.89 [1H, dd, J
=
Packing in 3b and 3c consists of an interconnecting network
of cations and anions. The crystallographic asymmetric unit
in 3b contains two ionic pairs, each with two C–H ؒ ؒ ؒ π
contacts [H(4) ؒ ؒ ؒ C(21)–C(26) centroid 2.58, H(1) ؒ ؒ ؒ C(9)–
C(14) centroid 2.71 and H(4B) ؒ ؒ ؒ C(45)–C(50) centroid
2.44, H(1B) ؒ ؒ ؒ C(39)–C(44) centroid 2.62 Å]. These pairs
are interconnected by further C–H ؒ ؒ ؒ π contacts building
a column along the b-axis [H(5) ؒ ؒ ؒ C(33)–C(38) centroid
2.45, H(8Ba) ؒ ؒ ؒ C(21)–C(26) centroid 2.74 Å]. In 3c the
imidazolium units are arranged in layers and face each other
2
᎐
᎐
2
gem
3
15.5 Hz, J(Z) = 2.8 Hz, NCH᎐CHNCH᎐C(Htrans)Hcis], 5.43
᎐
᎐
2
3
[1H, dd, Jgem = 8.6 Hz, J(Z) = 2.8 Hz, NCH᎐CHNCH᎐C-
᎐
᎐
(Htrans)Hcis], 5.17 [2H, d, 2Jgem = 2.5 Hz, HCCCH2NCHN], 3.08
[1H, t,4J = 2.7 Hz, HCCCH2NCHN]; δC (CD3CN, 151 MHz)
136.1 (s, NCHN), 129.5 (s, NCH᎐CHNCH᎐CH ), 123.7 (s,
᎐
᎐
2
NCH᎐CHNCH᎐CH ), 120.8 (s, NCH᎐CHNCH᎐CH ), 110.6
᎐
᎐
᎐
᎐
2
2
(s, NCH᎐CHNCH᎐CH ), 78.8 (s, HCCCH NCHN), 75.2 (s,
᎐
᎐
2
2
HCCCH2NCHN), 40.4 (s, HCCCH2NCHN); m/z (EI, 70 eV)
᎐
133 (M Ϫ Br, 11%), 94 (M–Br–CH C᎐CH, 100%), 39
᎐
2
Ϫ
with PF6 anions sandwiched between these layers. The
᎐
(CH C᎐CH, 92%).
᎐
2
Co2(CO)6 units face each other in the alternate layers, and
C–H ؒ ؒ ؒ F [F(2) ؒ ؒ ؒ H(4) 2.47, F(3) ؒ ؒ ؒ H(3A) 2.60,
F(4) ؒ ؒ ؒ H(5) 2.37, F(6) ؒ ؒ ؒ H(4) 2.45 Å] and O ؒ ؒ ؒ H
[O(4) ؒ ؒ ؒ H(5) 2.50 Å] interactions dominate lattice
arrangement.
᎐
Preparation of [HC᎐CCH N᎐C(H)N(CH᎐CH )CH᎐CH]B-
᎐
᎐
᎐
᎐
2
2
(C6H5)4, 1b. The addition NH4B(C6H5)4 (6.43 g, 18.8 mmol) to a
solution of 1a (2.0 g, 9.4 mmol) in H2O (40 cm3) and stirring for
5 min., yielded a colourless precipitate (4.11 g, 97%) of 1b after
extraction with CH2Cl2 (3 × 50 cm3), washing of the extract
with H2O (2 × 100 cm3), drying with MgSO4 and removal of the
solvent in vacuo; mp 170–171 ЊC (Found: C, 84.82; H, 6.64; N,
6.31, C32H29BN2 requires C, 84.96; H, 6.46; N, 6.19%); selected
νmax/cmϪ1 (KBr) 3249w [H–CCCH N], 3098w, 3052w (H–C᎐C),
Conclusions
The imidazolium salts 1a–c and 2a prepared from commercially
available starting materials have the advantage that the N
substituents carry alkene and alkyne groups which are available
for derivatisation creating possibilities for a multitude of new
imidazolium salts and ionic liquids.
Cobalt complexes of the imidazolium salts, 3a–c, 4a and 4b
were purified and isolated by exploiting differences in solubility
upon variation of the counteranion. Compound 4b melting at
75 ЊC qualifies as an ionic liquid.
᎐
2
᎐
2134m (C᎐C); δ (CD Cl , 600 MHz) 7.53 [8H, m, C H -ortho],
7.02 [8H, t, J = 7.4 Hz, C6H5-meta], 6.79 [4H, m, J = 7.4 Hz,
C H -para], 6.66 [1H, m, J = 1.7 Hz, NCH᎐CHNCH᎐CH ],
᎐
H
2
2
6
5
3
3
3
᎐
᎐
6
5
2
3
6.62 [1H, m, J = 1.7 Hz, NCH᎐CHNCH᎐CH ], 6.15 [1H, dd,
᎐
᎐
2
3J(E) = 15.6 Hz, J(Z) = 8.5 Hz, NCH᎐CHNCH᎐CH ], 5.26
3
᎐
᎐
2
[1H, dd, Jgem = 15.6 Hz, 3J(Z) = 3.2 Hz, NCH᎐CHNCH᎐
2
᎐
᎐
᎐
C(Htrans)Hcis], 5.18 [1H, dd, 2Jgem = 8.8 Hz, 3J(Z) = 3.2 Hz, NCH᎐
The imidazolium protons, NC(H)N and NCH᎐CHN, in
᎐
CHNCH᎐C(Htrans)Hcis], 4.81 [1H, br s, NCHN], 3.98 [2H, d,
᎐
compounds 1b and 3b containing the tetraphenylborate anion
experience π-interaction with the phenyl rings of the anion both
in solution and in the solid state.
4
2Jgem = 2.4 Hz, HCCCH2NCHN], 2.65 [1H, t, J = 2.7 Hz,
1
HCCCH2NCHN]; δC (CD2Cl2, 151 MHz) 164.6 (q, JBC
=
48 Hz, C6H5-ipso), 135.8 (s, C6H5-ortho), 134.3 (s, NCHN),
128.0 (s, NCH᎐CHNCH᎐CH ), 126.5 (q, 3JBC = 2.9 Hz, C6H5-
᎐
᎐
2
meta), 122.5 (s, C H -para), 121.6 (s, NCH᎐CHNCH᎐CH ),
᎐
᎐
6
5
2
Experimental
118.0 (s, NCH᎐CHNCH᎐CH ), 109.8 (s, NCH᎐CHNCH᎐
᎐
᎐
᎐
᎐
2
General
CH2), 78.1 (s, HCCCH2NCHN), 73.2 (s, HCCCH2NCHN),
39.6 (s, HCCCH2NCHN); m/z (EI, 70 eV) 452 [Mϩ, 0.2%], 242
[B(C6H5)3, 54%], 164 [B(C6H5)2, 100%].
Reactions were carried out under argon using standard Schlenk
and vacuum-line techniques. Tetrahydrofuran and diethyl ether
were distilled under N2 from sodium diphenylketyl, CH2Cl2
from CaH2 and hexane from sodium. All starting materials are
commercially available and were used without further purifi-
᎐
Preparation of [HC᎐CCH N᎐C(H)N(CH᎐CH )CH᎐CH]-
᎐
᎐
᎐
᎐
2
2
PF6, 1c. Compound 1c was prepared in the same fashion as 1b
D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
4278

View Article Online
from 1a (1.0 g, 4.7 mmol) and NH4PF6 (1.53 g, 9.39 mmol)
to yield a colourless precipitate (0.63 g, 48%); mp 86–88 ЊC
(Found: C, 34.77; H, 3.08; N, 9.66, C8H9F6N2P requires C,
(s, NCH᎐CHNCH᎐CH ), 111.6 (s, NCH᎐CHNCH᎐CH ),
᎐ ᎐ ᎐ ᎐
2 2
87.2 (s, HCCCH2NCHN), 74.9 (s, HCCCH2NCHN), 53.3
(s, HCCCH2NCHN); m/z (FAB, positive ion) 418.83
(C14H9Co2N2O6ϩ, 100%).
34.55; H, 3.26; N, 10.07%); selected νmax/cmϪ1 (KBr) 3292m
᎐
[H–CCCH N], 3163m (H–C᎐C), 2141m (C᎐C); δ (CD2Cl2,
᎐
᎐
2
H
600 MHz) 8.89 [1H, s, NCHN], 7.60 [1H, m, NCH᎐CHNCH᎐
᎐
᎐
CH ], 7.58 [1H, m, NCH᎐CHNCH᎐CH ], 7.08 [1H, dd, 3J(E) =
Preparation of [{ꢀ -HCCCH N᎐C(H)N(CH᎐CH )CH᎐CH}-
᎐
᎐
᎐
2
2
2
᎐
᎐
2
2
3
Co2(CO)6]B(C6H5)4, 3b. The addition of Co2(CO)8 (0.83 g,
2.43 mmol) to a solution of 1b (1.00 g, 2.2 mmol) in CH2Cl2
(80 cm3) and strirring for 1h at room temperature produced an
orange–brown solution. After reducing the solvent in vacuo the
residue was washed with diethyl ether (2 × 50 cm3) to extract
the unreacted Co2(CO)8. The product was extracted with a
H2O/CH2Cl2 (200/150 cm3) mixture. The organic layer was
washed with water (100 cm3), dried with anhydrous Na2SO4 and
evaporated to dryness in vacuo after filtration, to yield red
microcrystalline material (0.81 g, 50%), mp 75 ЊC (decomp.)
(Found: C, 61.82; H, 3.86; N, 3.68, C38H29BCo2N2O6 requires C,
61.82; H, 3.96; N, 3.79%); selected νmax/cmϪ1 (KBr) 3136w
15.5 Hz, J(Z) = 8.4 Hz, NCH᎐CHNCH᎐CH ], 5.83 [1H, dd,
᎐
᎐
2
2Jgem = 15.5 Hz, J(Z) = 3.1 Hz, NCH᎐CHNCH᎐C(Htrans)Hcis],
3
᎐
᎐
2
3
5.54 [1H, dd, Jgem = 8.4 Hz, J(Z) = 3.1 Hz, NCH᎐CHNCH᎐
᎐
᎐
2
C(Htrans)Hcis], 5.09 [2H, d, Jgem = 2.7 Hz, HCCCH2NCHN],
2.85 [1H, t, 4J = 2.5 Hz, HCCCH2NCHN]; δC (CD2Cl2,
151 MHz) 134.5 (s, NCHN), 128.1 (s, NCH᎐CHNCH᎐CH ),
᎐
᎐
2
123.0 (s, NCH᎐CHNCH᎐CH ), 120.1 (s, NCH᎐CHNCH᎐
᎐
᎐
᎐
᎐
2
CH ), 111.7 (s, NCH᎐CHNCH᎐CH ), 78.8 (s, HCCCH -
᎐
᎐
2
2
2
NCHN), 73.1 (s, HCCCH2NCHN), 40.4 (s, HCCCH2NCHN),
1
δP (CH2Cl2, 243 MHz) Ϫ143.3 (sp, JPF = 711.6 Hz, PF6Ϫ);
Ϫ
m/z (EI, 70 eV) 131 (M Ϫ PF6Ϫ, 35%), 107 (M Ϫ PF6
CHCH2, 100%), 94 (M Ϫ PF6Ϫ Ϫ CH2CCH, 53%).
Ϫ
[H–CCCo (CO) ], 3066w (H–C᎐C), 2114vs (C–O), 2068vs
᎐
2
6
(C–O), 2045vs (C–O), 2017vs (C–O), 1542m [CCCo2(CO)6];
δH (CD2Cl2, 300 MHz) 7.48 [8H, br s, C6H5-ortho], 7.04 [8H, t,
3J = 7.3 Hz, C H -meta], 6.93–6.85 [5H, m, NCH᎐CHNCH᎐
᎐
Preparation of [HC᎐CCH N᎐C(H)N(CH CH᎐CH )CH᎐C-
᎐
᎐
᎐
᎐
2
2
2
H]Br, 2a. Compound 2a was prepared in the same way as 1a
᎐
᎐
6
5
from 1-allyl-1H-imidazole (5.0 cm3, 44.0 mmol) and 80%
CH , C H -para], 6.71 [1H, s, NCH᎐CHNCH᎐CH ], 6.26 [1H,
᎐
᎐
2
3
6
5
2
3
3
᎐
HC᎐CCH Br in toluene (7.2 cm , 65 mmol) and colourless,
᎐
2
dd, J(E) = 15.5 Hz, J(Z) = 8.8 Hz, NCH᎐CHNCH᎐CH ],
᎐ ᎐
2
6.06 [1H, s, HCCCH2NCHN] 5.38–5.21 [3H, m, 3J(Z) = 8.8 Hz,
2Jgem = 3.2 Hz, NCHN, NCH᎐CHNCH᎐C(Htrans)Hcis], 4.53
hygroscopic crystals of 2a (10.8 g, 98%) were obtained, mp 65–
66 ЊC (Found: C, 47.23; H, 5.50; N, 11.98, C9H11BrN2 requires
C, 47.60; H, 4.88; N, 12.34%); selected νmax/cmϪ1 (KBr) 3186w,
3120w [H–C᎐CCH N], 3087w, 3045w (H–C᎐C), 2116m (C᎐C);
δH (CD3CN, 600 MHz) 9.48 [1H, s, NCHN], 7.67 [1H, t, J =
᎐
᎐
[2H, s, HCCCH2NCHN]; δC (CD2Cl2, 75 MHz) 198.7 (s, CO),
᎐
᎐
᎐
᎐
᎐
2
164.7 (q, 1JBC = 48.8 Hz, C6H5-ipso), 136.2 (s, C6H5-ortho), 134.3
3
3
(s, NCHN), 128.1 (s, NCH᎐CHNCH᎐CH ), 126.6 (q, J
=
᎐
᎐
2
BC
3
1.7 Hz, NCH᎐CHNCH CH᎐CH ], 7.56 [1H, t, J = 1.7 Hz,
᎐
᎐
2
2
1.9 Hz, C H -meta), 122.7 (s, C H -para), 122.4 (s, NCH᎐
᎐
6 5 6 5
CHNCH᎐CH ), 118.9 (s, NCH᎐CHNCH᎐CH ), 110.6 (s,
᎐ ᎐ ᎐
2 2
NCH᎐CHNCH᎐CH ), 84.9 (s, HCCCH NCHN), 74.5 (s,
᎐ ᎐
2 2
NCH᎐CHNCH CH᎐CH ], 6.05 [1H, m, 3J(E) = 17.0 Hz,
᎐
᎐
3J(Z) = 10.4 Hz, 3J =2 6.3 Hz, NCH᎐CHNCH CH᎐CH ],
2
᎐
᎐
2
2
5.40 [2H, m, NCH᎐CHNCH CH᎐C(Htrans)Hcis], 5.25 [2H, d,
᎐
᎐
2
HCCCH2NCHN), 52.2 (s, HCCCH2NCHN); m/z (FAB,
2J = 2.7 Hz, HCCCH2NCHN], 4.90 [2H, dt, J = 1.3 Hz, J =
4
3
positive ion) 418.9 (C14H9Co2N2O6ϩ, 26%).
6.3 Hz, NCH᎐CHNCH (H )CH᎐C(Htrans)Hcis], 3.13 [1H, t, 4J =
᎐
᎐
a
e
2.7 Hz, HCCCH2NCHN]; δC (CD3CN, 151 MHz) 137.1 (s,
NCHN), 131.1 (s, NCH᎐CHNCH CH᎐CH ), 123.7 (s, NCH᎐
Preparation of [{ꢀ -HCCCH N᎐C(H)N(CH᎐CH )CH᎐CH}-
᎐
᎐
᎐
2
2
2
᎐
᎐
᎐
2
2
Co2(CO)6]PF6, 3c. Compound 3c was prepared in the same
way as 3b from 1c (0.21 g, 0.77 mmol) and Co2(CO)8 (0.27 g,
0.79 mmol). Orange, microcrystalline material (0.15 g, 34%)
was obtained, mp 132 ЊC (decomp.) (Found: C, 29.61; H,
1.82; N, 5.04, C14H9Co2F6N2O6P requires C, 29.81; H, 1.61; N,
4.97%); selected νmax/cmϪ1 (KBr) 3161w, 3114w [H–CCCo2-
CHNCH CH᎐CH ), 123.2 (s, NCH᎐CHNCH CH᎐CH ),
᎐
᎐
᎐
2
2
2
2
121.9 (s, NCH᎐CHNCH CH᎐CH ), 78.4 (s, HCCCH NCHN),
᎐
᎐
2
2
2
75.6 (s, HCCCH NCHN), 52.6 (s, NCH᎐CHNCH CH᎐CH ),
᎐
᎐
2
2
2
40.2 (s, HCCCH2NCHN); m/z (EI, 70 eV) 227 (Mϩ, 10%), 147
(M Ϫ Br, 30%).
(CO) ], 3053w (H–C᎐C), 2102vs (C–O), 2061vs (C–O), 2030vs
(C–O), 1554m [CCCo2(CO)6]; δH (CD2Cl2, 600MHz) 9.01 [1H,
᎐
6
Preparation of [{ꢀ -HCCCH N᎐C(H)N(CH᎐CH )CH᎐CH}-
᎐
᎐
᎐
2
2
2
Co2(CO)6]BF4, 3a. The addition of Co2(CO)8 (4.62 g, 13.51
mmol) to a solution of 1a (1.73 g, 8.11 mmol) in CH2Cl2
(80 cm3) and THF (20 cm3) and strirring for 3 days at room
temperature produced an orange–brown precipitate. After
removal of the solvent the residue was treated with water (1000
cm3) and the unreacted Co2(CO)8 was extracted with diethyl
ether (100 cm3). After addition of NH4BF4 (1.30 g, 12.40 mmol)
and stirring for 5 min., the orange mixture was extracted with
CH2Cl2 (3 × 150 and 1 × 50 cm3). The combined organic layers
were washed with water (3 × 250 cm3), dried with anhydrous
MgSO4 and evaporated to dryness in vacuo after filtration, to
yield orange microcrystalline material (0.67 g, 16%), mp 129 ЊC
(decomp.) (Found: C, 32.91; H, 2.10; N, 5.93, C14H9BCo2-
F4N2O6 requires C, 33.24; H, 1.79; N, 5.53%); selected νmax/cmϪ1
s, NCHN], 7.61 [1H, m, NCH᎐CHNCH᎐CH ], 7.52 [1H, m,
᎐
᎐
2
3
3
NCH᎐CHNCH᎐CH ], 7.11 [1H, dd, J(E) = 15.1 Hz, J(Z) =
᎐
᎐
2
8.5 Hz, NCH᎐CHNCH᎐CH ], 6.36 [1H, s, HCCCH NCHN],
᎐
᎐
2
2
3
5.82 [1H, d, J(E) = 15.1 Hz, NCH᎐CHNCH᎐C(Htrans)Hcis],
᎐
᎐
5.55–5.50 [3H, m, HCCCH2NCHN, NCH᎐CHNCH᎐
᎐
᎐
C(Htrans)Hcis]; δC (CD2Cl2, 151 MHz) 198.5 (s, CO), 134.9 (s,
NCHN), 128.1 (s, NCH᎐CHNCH᎐CH ), 123.6 (s, NCH᎐
᎐
᎐
᎐
2
CHNCH᎐CH ),120.0(s,NCH᎐CHNCH᎐CH ),111.8(s,NCH᎐
᎐
᎐
᎐
᎐
2
2
CHNCH᎐CH ), 86.5 (s, HCCCH NCHN), 74.7 (s, HCCCH -
᎐
2
2
2
NCHN), 53.4 (s, HCCCH2NCHN), δP (CH2Cl2, 243 MHz)
1
Ϫ143.7 (sp, JPF = 711.6 Hz, PF6Ϫ); m/z (FAB, positive ion)
418.9 (C14H9Co2N2O6ϩ, 100%).
(KBr) 3182w, 3150w [H–CCCo2(CO)6], 3108w (H–C᎐C),
Preparation of [{ꢀ -HCCCH N᎐C(H)N(CH CH᎐CH )CH᎐C-
᎐ ᎐ ᎐
2 2 2 2
᎐
2101vs (C–O), 2049vs (C–O), 2022vs (C–O), 1573m
[CCCo2(CO)6]; δH (CD3CN, 200 MHz) 8.99 [1H, s, NCHN],
H}Co2(CO)6]BF4, 4a. Complex 4a was prepared in the fashion
as 3a from 2a (1.60 g, 7.05 mmol), Co2(CO)8 (2.53 g, 7.40
mmol), and NH4BF4 (0.96 g, 9.16 mmol) (used in the water
extraction). Dark red, microcrystalline material (1.05 g, 29%)
was obtained, mp 76 ЊC (decomp.) (Found: C, 34.38; H, 2.08; N,
5.19, C15H11BCo2F4N2O6 requires C, 34.65; H, 2.13; N, 5.39%);
selected νmax/cmϪ1 (KBr) 3139w [H–CCCo2(CO)6], 3101w,
7.79 [1H, m, NCH᎐CHNCH᎐CH ], 7.69 [1H, m, NCH᎐
᎐
᎐
᎐
2
CHNCH᎐CH ], 7.19 [1H, dd, 3J(E) = 15.8 Hz, 3J(Z) = 8.8 Hz,
᎐
2
NCH᎐CHNCH᎐CH ], 6.51 [1H, s, HCCCH NCHN] 5.85 [1H,
᎐
᎐
2
2
dd, 3J(E) = 15.6 Hz, 2J(Z) = 3.0 Hz, NCH᎐CHNCH᎐C-
᎐
᎐
(Htrans)Hcis], 5.55 [2H, s, HCCCH2NCHN], 5.46 [1H, dd, 3J(E) =
8.6 Hz, 2J(Z)
2.8 Hz, NCH᎐CHNCH᎐C(Htrans)Hcis];
δC (CD2Cl2, 75 MHz) 199.4 (s, CO), 136.1 (s, NCHN), 128.6 (s,
NCH᎐CHNCH᎐CH ), 123.6 (s, NCH᎐CHNCH᎐CH ), 120.0
=
(H–C᎐C), 2102vs (C–O), 2060vs (C–O), 2010vs (C–O), 1557m
᎐
᎐
᎐
[CCCo2(CO)6]; δH (CH2Cl2, 300 MHz) 9.10 [1H, s, NCHN],
7.50 [1H, m, NCH᎐CHNCH CH᎐CH ], 7.38 [1H, m, NCH᎐
᎐
᎐
᎐
᎐
᎐
᎐
᎐
2
2
2
2
D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
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Table 2 Crystal data and structure refinement for 3b and 3c
3b
3c
Molecular formula
Mr
C38H29BCo2N2O6
738.30
C14H9Co2F6N2O6P
564.06
Crystal system
Space group
Triclinic
P1 (no. 2)
Triclinic
P1 (no. 2)
¯
¯
Unit cell dimensions
a/Å
b/Å
c/Å
α/Њ
β/Њ
9.4434(2)
17.5931(5)
21.6424(7)
99.918(2)
98.869(2)
91.452(2)
3494.58(17)
4
8.089(2)
9.378(2)
14.739(4)
85.89(2)
87.19(2)
66.28(2)
1020.7(4)
2
γ/Њ
V/Å3
Z
T/K
233(3)
1.403
0.998
203(2)
1.835
1.791
Dc/g cmϪ3
µ/mmϪ1
F(000)
Color, habit
1512
556
Red prism
0.3 × 0.14 × 0.09
1.65–23.00
0 to 10; Ϫ19 to 19; Ϫ23 to 23
17646
9694 (0.0252)
7664
Orange prism
0.7 × 0.3 × 0.25
4.09–25.00
Ϫ1 to 9; Ϫ11 to 11; Ϫ17 to 17
4392
3578 ( 0.0191)
3006
ψ-Scans
Crystal size/mm
θ-Range for data collection/Њ
Index ranges, hkl
No. of reflections collected
No. of independent reflections (Rint
No. of reflections with I > 2σ(I )
Absorption correction
Max., min. transmission
Refinement method
Data, restraints, parameters
Goodness-of-fit on F 2
Final R indices [I > 2σ(I )]
R indices (all data)
Extinction coefficient
Largest diff. peak and hole/e nmϪ3
)
None
0.842, 0.671
Full-matrix least squares on F 2
9694, 0, 892
1.051
R1 = 0.0419; wR2 = 0.1016
R1 = 0.0588; wR2 = 0.1019
0.0006(2)
Full-matrix least squares on F 2
3578, 0, 303
1.036
R1 = 0.0331; wR2 = 0.0815
R1 = 0.0432; wR2 = 0.0854
0.0001(10)
1267 and Ϫ813
459 and Ϫ268
CHNCH CH᎐CH ], 6.38 [1H, s, HCCCH NCHN], 5.98 [1H,
X-Ray crystal structure determinations
᎐
2
2
2
m, NCH᎐CHNCH CH᎐CH ], 5.53 [2H, s, HCCCH NCHN],
᎐
᎐
2
2
2
Crystal structure determination of 3b and 3c. Single crystals
of 3b or 3c suitable for X-ray analysis, were obtained by slow
crystallisation from dichloromethane or dichloromethane/
diethyl ether.
5.50 [1H, m, NCH᎐CHNCH CH᎐C(Htrans)Hcis], 5.47 [1H, m,
᎐
᎐
2
2
NCH᎐CHNCH CH᎐C(Htrans)Hcis], 4.83 [2H, dm, J = 6.5 Hz,
᎐
᎐
2
NCH᎐CHNCH (H )CH᎐C(Htrans)Hcis]; δC (CH2Cl2, 75 MHz)
᎐
᎐
a
e
198.9 (s, CO), 136.8 (s, NCHN), 129.8 (s, NCH᎐CHNCH CH᎐
᎐
᎐
2
For compound 3b a Nonius Kappa CCD diffractometer with
graphite-monochromated Mo-Kα radiation was used and the
raw data were processed with the program DENZO-SMN34 to
obtain the conventional data. For compound 3c a Bruker P4
diffractometer with graphite monochromated Mo-Kα radiation
(λ = 0.71073 Å) was used for data collection. Intensities were
measured via ω-scans and corrected for Lorentz and polaris-
ation effects. The structure was solved by direct methods
CH ), 123.4 (s, NCH᎐CHNCH CH᎐CH ), 123.2 (s, NCH᎐
᎐
᎐
᎐
2
2
2
CHNCH CH᎐CH ), 122.7 (s, NCH᎐CHNCH CH᎐CH ), 87.6
᎐
᎐
᎐
2
2
2
2
(s, HCCCH2NCHN), 74.8 (s, HCCCH2NCHN), 52.9 (s,
HCCCH NCHN), 52.8 (s, NCH᎐CHNCH CH᎐CH ); m/z
᎐
᎐
2
2
2
(FAB, positive ion) 432.9 (C15H11Co2N2O6ϩ, 100%).
Preparationof[{ꢀ -HCCCH N᎐C(H)N(CH CH᎐CH )CH᎐C-
᎐
᎐
᎐
2
2
2
2
(SHELXS-86)35 and refined by full-matrix least squares against
H}Co2(CO)6]PF6, 4b. The salt 4b was obtained in a similar
fashion to 3a from 2a (2.00 g, 8.81 mmol), Co2(CO)8 (3.16 g,
9.24 mmol), and NH4PF6 (1.58 g, 9.69 mmol) (used in the water
extraction). Red microcrystalline material (1.09 g, 21%) was
obtained, mp 75–77 ЊC (reversible) (Found: C, 31.11; H, 1.90;
N, 4.92, C15H11Co2F6N2O6P requires C, 31.17; H, 1.92; N,
4.85%); selected νmax/cmϪ1 (KBr) 3154w [H–CCCo2(CO)6],
2
F 2 (SHELXL-97).36 The function minimized was Σ[w(Fo
Ϫ
Fc2)2] with the weight defined as wϪ1 = [σ2(Fo ) ϩ (xP)2 ϩ yP]
2
and P = (Fo ϩ 2Fc2)/3. All non-hydrogen atoms were refined
2
with anisotropic displacement parameters. The hydrogen atoms
at the ethynyl groups of 3b and 3c were refined isotropically; all
others were placed on calculated positions. The atoms of the
ethenyl group in 3c were split in two positions by a 3 : 1 disorder
3090w, (H–C᎐C), 2119vs (C–O), 2059vs (C–O), 1989vs (C–O),
᎐
1560m [CCCo2(CO)6]; δH (CD2Cl2, 300 MHz) 8.80 [1H, s,
NCHN], 7.45 [1H, m, NCH᎐CHNCH CH᎐CH ], 7.36
of C(7)᎐C(8) and C(7A)᎐C(8A), leading to more inexact bond
᎐
᎐
distances and angles around this group by correlation effects.
Further crystallographic data are collected in Table 2.
CCDC reference numbers 215682 and 215683.
See http://www.rsc.org/suppdata/dt/b3/b308252k/ for crystal-
lographic data in CIF or other electronic format.
᎐
᎐
2
2
[1H, m, NCH᎐CHNCH CH᎐CH ], 6.37 [1H, s, HCCCH -
᎐
᎐
2
2
2
NCHN], 5.97 [1H, m, NCH᎐CHNCH CH᎐CH ], 5.54 [1H, br
᎐
᎐
2
2
s, HCCCH2NCHN], 5.49 [3H, br s, HCCCH2NCHN and
2
NCH᎐CHNCH CH᎐C(Htrans)Hcis], 4.82 [2H, d, J = 6.3 Hz,
᎐
᎐
2
NCH᎐CHNCH (H )CH᎐C(Htrans)Hcis]; δC (CD2Cl2, 75 MHz)
᎐
᎐
a
e
198.7 (s, CO), 136.2 (s, NCHN), 129.4 (s, NCH᎐CHNCH CH᎐
᎐
᎐
2
CH ), 123.9 (s, NCH᎐CHNCH CH᎐CH ), 123.2 (s, NCH᎐
᎐
᎐
᎐
2
2
2
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᎐
᎐
᎐
2
2
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D a l t o n T r a n s . , 2 0 0 3 , 4 2 7 5 – 4 2 8 1
4280

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