A halogenophilic pathway in the reactions of transition metal carbonyl anions with [(η6-iodobenzene)Cr(CO)3]

Article abstract of DOI:10.1039/c4dt01363h

The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in Cr(CO)₃ complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack [(η⁶-iodobenzene)Cr(CO)₃] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The reaction with K[CpFe(CO) ₂] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)₂] (Cp* = η⁵-C ₅Me₅) results in nucleophilic substitution to give [(η⁶-C₆H₅FeCp*(CO) ₂)Cr(CO)₃]. Reaction with Na[Re(CO)₅] quantitatively gives the iodo(acyl)rhenate anion Na[(η⁶-C ₆H₅C(O)ReI(CO)₄)Cr(CO)₃] and in the case of K[Mn(CO)₅] a mixture of σ-aryl complexes [(η⁶-C₆H₅Mn(CO)₅)Cr(CO) ₃] and K[(η⁶-C₆H₅Mn(CO) ₄I)Cr(CO)₃]. An analogous rhenium complex Na[(η⁶-C₆H₅Re(CO)₄I)Cr(CO) ₃] is formed from the initial iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt₄] ⁺ salt) is established by X-ray diffraction analysis. The reaction of [(η⁶-chlorobenzene)Cr(CO)₃] with K[CpFe(CO) ₂], in contrast, proceeds by the common S_N2Ar mechanism.

Full text of DOI:10.1039/c4dt01363h

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A halogenophilic pathway in the reactions
of transition metal carbonyl anions with
Cite this: Dalton Trans., 2014, 43,
13392
[(η6-iodobenzene)Cr(CO)3]†
Petr K. Sazonov,*a Vasiliy A. Ivushkin,a Victor N. Khrustalev,b Natal’ya G. Kolotyrkinac
and Irina P. Beletskaya*a
The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in
Cr(CO)3 complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack
[(η6-iodobenzene)Cr(CO)3] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The
reaction with K[CpFe(CO)2] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)2]
(Cp* = η5-C5Me5) results in nucleophilic substitution to give [(η6-C6H5FeCp*(CO)2)Cr(CO)3]. Reaction with
Na[Re(CO)5] quantitatively gives the iodo(acyl)rhenate anion Na[(η6-C6H5C(O)ReI(CO)4)Cr(CO)3] and in
the case of K[Mn(CO)5] a mixture of σ-aryl complexes [(η6-C6H5Mn(CO)5)Cr(CO)3] and K[(η6-C6H5Mn-
(CO)4I)Cr(CO)3]. An analogous rhenium complex Na[(η6-C6H5Re(CO)4I)Cr(CO)3] is formed from the initial
iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt4]+ salt) is estab-
lished by X-ray diffraction analysis. The reaction of [(η6-chlorobenzene)Cr(CO)3] with K[CpFe(CO)2],
in contrast, proceeds by the common SN2Ar mechanism.
Received 7th May 2014,
Accepted 10th July 2014
DOI: 10.1039/c4dt01363h
www.rsc.org/dalton
aromatic substitution and haloarene reduction. It was con-
cluded, however, that more detailed studies are required to
Introduction
Nucleophilic substitution with a transition-metal centered define both the mechanism of the substitution and the
nucleophile is arguably one of the easiest ways to form a tran- relationship between the substitution and dehalogenation
sition-metal carbon σ-bond. For more than five decades metal processes.8
carbonyl anions, carbonylmetallates, have been widely used
On the other hand, transition metal carbonyl anions gained
for that purpose due to their nucleophilic reactivity, availability significant importance as model systems in organometallic
and better stability, compared to other transition metal chemistry, and were used by our group to study the mecha-
anions.1–7 Besides aliphatic substitution, carbonylmetallates nisms of nucleophilic vinylic and aromatic substitution by
can also be used to create a transition metal–sp2-carbon bond metal-centered nucleophiles. In the reactions with halopenta-
in nucleophilic vinylic and aromatic substitution reactions. fluorobenzenes13,14 and bromotrifluoroethylene15 we were able
Among the notable examples are the reactions of carbonyl- to prove a halogenophilic mechanism of nucleophilic substi-
metallates with Cr(CO)3 π-complexes of haloarenes leading to tution. In this pathway, carbonylmetallate first attacks not at
heterobimetallic complexes with a bridging σ,π-arene ligand.8–10 the carbon atom, but at the halogen, and the “normal” nucleo-
Complexation with Cr(CO)3 activates haloarene towards philic substitution product is formed in the second step by the
nucleophilic attack,11,12 and these reactions display rather a coupling of carbanions and metal carbonyl halide intermedi-
rich and interesting chemistry of competitive nucleophilic ates (Scheme 1).
Later it was shown that the halogenophilic attack is one of
the major pathways in the reactions of carbonylmetallates with
aChemistry Department of the M.V. Lomonosov Moscow State University, 119992
vinyl halides.16,17 However, the scope of the same mechanism
Moscow, Russia. E-mail: beletska@org.chem.msu.ru, petr@elorg.chem.msu.ru;
in aromatic substitution with carbonylmetallates remained
Fax: +7 495 939 3618
bA.N. Nesmeyanov Institute of Organoelement Compounds (INEOS), Russian
unexplored, the known examples are still limited to the penta-
fluorophenyl halides. The aim of this work is to study the
reaction mechanism of carbonylmetallates with Cr(CO)3
π-complexes of chloro- and iodobenzene, and to seek evidence
for or against the halogenophilic pathway in both substitution
and competing reduction processes.
Academy of Sciences, Vavilov Street 28, 119991 Moscow, Russia
cND Zelinsky Institute of Organic Chemistry, Department of Structural Studies (IOC),
Russian Academy of Sciences, Moscow 119991, Russia
†Electronic supplementary information (ESI) available. CCDC 999498. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c4dt01363h
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Table 1 Products of the reaction of (η6-C6H5X)Cr(CO)3 (X = Cl, I) with
K[(C5R5)Fe(CO)2] (R = H, CH3), THF, 22 °C
Product yieldsa/%
(Ar = (η6-C6H5)Cr(CO)3)
Reagent and
additive
ArFp or
ArFp*
Fp2 or
(Fp*)2
Entry
ArX
ArH
1
2
3
4
5
(C6H5Cl)Cr(CO)3
(C6H5Cl)Cr(CO)3
(C6H5I)Cr(CO)3
(C6H5I)Cr(CO)3
(C6H5I)Cr(CO)3
KFp, no additive
KFp, t-BuOH
KFp, no additive
K[Fp*], no additive
K[Fp*], t-BuOH
80
80
—
60
—
7
11
25
15
50
16
16
∼100
25
∼100
a Product yields were determined by 1H NMR spectroscopy using durene as
the internal standard.
Scheme 1 The halogenophilic mechanism of nucleophilic vinylic
substitution.
Results and discussion
The reaction of Cr(CO)3 complexes of chlorobenzenes with
K[CpFe(CO)2] (KFp) was studied most extensively by Heppert
et al.8 The reaction usually gives the nucleophilic substitution
products (ArFp) in good yields accompanied by minor
amounts of reduced haloarene (ArH) and [Fp]2. To test for aryl
carbanion intermediates in this reaction we performed it in
the presence of an “anion scavenger” – t-BuOH – the test pre-
viously used by us13–16 and others18–20 to detect the halogen-
ophilic reaction mechanism (Scheme 1). The yield of the ArFp
complex and the substitution–reduction product ratio (ArFp/
Fp2) did not change in the presence of t-BuOH (entry 2,
Table 1),‡ which effectively rules out the halogenophilic Scheme 2 Reaction of (η6-C6H5I)Cr(CO)3 with K[(C5R5)Fe(CO)2] (R =
H, CH3).
pathway for the nucleophilic substitution reaction.
Haloarene reduction becomes the only observed process in
the reaction of KFp with [(η6-iodobenzene)Cr(CO)3], with no
substitution product detected in the reaction mixture. A con-
Cr(CO)3 complexes of chlorobenzenes were previously
found to be unreactive towards Na[Re(CO)5] and other less
siderable amount of ArH formed without an added alcohol
nucleophilic carbonylmetallate anions.8 Bearing in mind that
may be explained by aryl carbanion proton abstraction from
iodoarenes are much more reactive in halogenophilic pro-
the Cp group of Fp2 or FpI. If this is indeed the case, one can
cesses than chloroarenes (by a factor of ∼106),17 we studied the
try to exclude this proton source (and aryl carbanion sink) by
replacing KFp with its pentamethylated analog, K[C5Me5Fe-
(CO)2] (K[Fp*]).
We were pleased to find that the reaction of K[Fp*] with
[(η6-C6H5I)Cr(CO)3] gave the [(η6-C6H5Fp*)Cr(CO)3] complex
with 60% yield (Scheme 2). The addition of t-BuOH to the reac-
tion mixture suppressed its formation, completely, proving the
halogenophilic pathway for this substitution reaction. The
amount of ArH formed in the presence of t-BuOH (0.5 mol per
mol of K[Fp*]) corresponds to a stoichiometry of halogeno-
philic reaction when it gives [Fp*]2 (eqn (1)).
ArI þ 2 K½Fp*ꢀ ! ½ArK þ Fp*Iꢀ þ K½Fp*ꢀ
t-BuOH
ꢁꢁꢁ! ArH þ ½Fp*ꢀ2 þ KI
ð1Þ
‡An increase of ArH yield from 7 to 11% in the presence of t-BuOH shows some
Scheme 3 Iodo(acyl)rhenate formation in the reaction of Na[Re(CO)5]
with (η6-C6H5I)Cr(CO)3.
aryl carbanions participation in the haloarene reduction process.
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Scheme 4 The reaction of [(η6-C6H5I)Cr(CO)3] with K[Mn(CO)5]. Effect of the “anion scavenger”.
reaction of [(η6-iodobenzene)Cr(CO)3] with the pentacarbonyl-
rhenate anion, Na[Re(CO)5]. The reaction actually gave a single
product with a quantitative yield, the iodo(acyl)rhenate anion§
expected for the halogenophilic mechanism (Scheme 3). The
isolation of the iodo(acyl)rhenate was not attempted, instead it
was characterized in solution by IR, 13C NMR (Fig. S1 and S2
of the ESI†) and HR ESI MS spectra. Halo(acyl)rhenate results
from the nucleophilic addition of carbanion to the equatorial
CO ligand of [Re(CO)5X],14,15 and thus provides direct
evidence of the intermediates generated in the halogenophilic
attack.
Table 2 Yields of the arene products in the reaction of [(η6-C6H5I)Cr
(CO)3] with K[Mn(CO)5], THF, 22 °C
Product yields/% (Ar = (η6-C6H5)Cr(CO)3)
Entry
Additive
K[ArMnI(CO)4]
[ArMn(CO)5]
ArH
1a
2b
3
—
40
50
—
18
—
—
15
20
78
18-crown-6
t-BuOH
a Minor amounts of [Mn(CO)5I] and [Mn2(CO)10] were also detected by
IR spectroscopy. b Minor amount of K[Mn(CO)4I2] also detected by IR.
The reactions of [(η6-iodobenzene)Cr(CO)3] with K[Fp*] or
Na[Re(CO)5] are instantaneous at room temperature, but its
reaction with less nucleophilic K[Mn(CO)5] is not, its progress
can be monitored spectroscopically and in this case a more
complex picture arises. Its main product is not the iodo(acyl)
manganate, by the analogy with Na[Re(CO)5], but the iodo
(aryl)manganate anion, K[ArMnI(CO)4] (Ar = (η6-C6H5)Cr(CO)3)
(Scheme 4, Table 2). The anionic product is easily identified by
its characteristic CO-signal patterns in IR and 13C NMR
spectra, closely resembling that of halo(acyl)metallates, but
with no bridging acyl carbon signal (δ >250 ppm, Fig. S3 and
S4 of the ESI†). In contrast to acylate anions, addition of
18-crown-6 has a negligible effect on the IR and NMR spectra
of K[ArMnI(CO)4], indicating that it forms solvent-separated
ion pairs in THF solution.
Also present in the mixture is the neutral pentacarbonyl-
manganese σ-aryl complex, [ArMn(CO)5], together with the
iodoarene reduction product, [(η6-C6H6)Cr(CO)3]. However,
K[ArMnI(CO)4] and [ArMn(CO)5] are not the initial products, as
they are both absent at the early stages of the reaction
(10–30 min) whereas the signals of the two intermediates are
seen in 1H and 13C NMR spectra (Fig. S5 of the ESI†).
(94.8, 91.7 ppm)¶. The IR band at 2073 cm−1 observed in the
first few minutes of reaction presumably also belongs to this
intermediate and is replaced towards the end of the reaction
(4 h) by the band at 2060 cm−1 belonging to K[ArMnI(CO)4]
(Fig. S6 of the ESI†).
Upon the addition of 18-crown-6 the band at 2073 cm−1 is
immediately replaced by the band at 2060 cm−1, which may be
explained by the dissociation of contact ion pairs of the iodo
(acyl)manganate intermediate (Fig. S7 and S8 of the ESI†).
Signals presumably belonging to this intermediate are also
observed in the 13C NMR spectrum of the reaction performed
in the presence of 18-crown-6 (93.63, 92.20, and 93.50 ppm).
The final product’s composition in the presence of 18-crown-6
is simpler and contains only K[ArMnI(CO)4] and ArH (entry 2,
Table 2) and minor amount of K[Mn(CO)4I2].
These observations lead one to conclude that acylmanga-
nate, K[ArC(O)MnI(CO)4] is the initial product of the reaction,
which then transforms into [ArMn(CO)5] and K[ArMnI(CO)4].
Besides, this is in good agreement with the previous data
on the facile decomposition of halo(acyl)manganates into
σ-aryl complexes in the reactions of K[Mn(CO)5] with C6F5X
(X = Br, I).14
The intermediate, appearing first and decaying faster
(∼1 h), exhibits signal patterns characteristic for a iodo(acyl)
manganate anion: the 13C NMR signal of the bridging CO
group at 285.6 ppm, the signal of C-para of the C6H5-group at
95.8 ppm, in lower field than that of ortho and meta carbons
Halogenophilic character of the [(η6-C6H5I)Cr(CO)3] reaction
with K[Mn(CO)5] was further confirmed by the aryl carbanion
intermediate trapping with the proton donor. With t-BuOH
added, no σ-aryl manganese complexes were formed, and
§Acylrhenate anions (and acylmetallates in general) are often described as oxy-
carbene complexes because of a large contribution of metal carbene resonance
structure, as evidenced by the downfield shift of acyl CO resonance in 13C NMR.
¶δ(Cpara) > δ(Cortho) is the trend observed for iodo(acyl)rhenate as opposed to
σ-aryl metal complexes, in which C-ortho signal is shifted downfield because of
the contribution of the metal carbene resonance structure (Fig. 1).
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Scheme 5 Pathway for iodo(aryl)manganate formation in the reaction of [(η6-C6H5I)Cr(CO)3] with K[Mn(CO)5].
[(η6-C6H6)Cr(CO)3] became the only arene product (Scheme 4, iodo(acyl)rhenate, Na[ArC(O)ReI(CO)4], on prolonged standing
entry 3, Table 2), while [Mn(CO)5I] was mainly trapped in the in THF solution was also transformed into analogous iodo
form of K[t-BuOC(O)Mn(CO)4I]14 and [Mn2(CO)10] according to (aryl)rhenate. After 6 months, only 17% of iodo(acyl)rhenate
the IR spectrum.
was left and iodo(aryl)rhenate, Na[ArReI(CO)4], was formed in
A rate plot consistent with second-order kinetics is observed 58% yield (eqn (2)). It was isolated in the solid state as an
for the reaction of [(η6-C6H5I)Cr(CO)3] with K[Mn(CO)5] in the [Et4N]+ salt (using the method from ref. 10) and its structure
presence of t-BuOH (Fig. S9 and S10 of the ESI†), allowing for was unambiguously established by single-crystal X-ray diffrac-
the second order rate constant (kobs = 0.031 l mol−1
calculated from these data. However, the same reaction
without an added proton donor is definitely slower (kobs
0.010–0.015) and deviates from the second order rate law. The
reversible halogen–metal exchange step in the case of relatively
weak K[Mn(CO)5] nucleophile may be the cause underlying
this kinetic behavior. We will refer here to the general
Scheme 1 because it shows the same mechanism; a reversible
halogen–metal exchange step means that k−1 > k2. When the
intermediate carbanion is captured by the proton donor, and
provided this step is sufficiently fast (kprot > k−1), the first step
s
−1) to be tion analysis.
=
Na½ðη6-C6H5CðOÞReðCOÞ4IÞCrðCOÞ3ꢀ
ꢁꢁꢁꢁꢁꢁ! Na½ðη6-C6H5ReðCOÞ4IÞCrðCOÞ3ꢀ
THF; 6 month
ð2Þ
ꢁCO
It should be pointed out that the 1H and 13C NMR signal
patterns of the K[ArMnI(CO)4] and of the isolated iodo(aryl)-
rhenate are quite similar, which confirms the identification of
the former.
The downfield shift of the signals of ortho-protons
(∼6.05 ppm) and ortho-carbons (∼113 ppm) is a distinctive
spectrum feature and reflects the contribution of the metal
carbene resonance structure (Fig. 1) in these complexes.
The structure of the iodo(aryl)rhenate complex is shown in
Fig. 2. The coordination around rhenium is approximately
octahedral, slightly distorted by an “umbrella” effect, the dis-
placement of the two mutually trans carbonyl groups (C12–O6
and C11–O5) towards the aryl ring.25–27 The octahedral
rhenium moiety adopts a “staggered” conformation relative to
the plane of the aryl ring (C12–Re–C1–C2 torsion angle 51.7°).
Iodine and the aryl group are expectedly in the cis-position,
which is the preferred configuration for [XYM(CO)4] (M = Mn,
Re) complexes. The Re1–C13 distance is significantly shorter
(1.898 Å) than the other three Re–CCO distances
(1.978–2.007 Å), reflecting the stronger trans-effect of CO and
aryl ligands compared to the iodide ligand.
becomes irreversible and the overall rate increases (kobs
kHME).
=
The transformation of acylmanganate K[ArC(O)MnI(CO)4]
into arylmanganate may go through the elimination of KI fol-
lowed by aryl migration, to give the neutral σ-aryl complex in
which the CO-ligand is then substituted by the iodide anion
(Scheme 5). However, [ArMn(CO)5] was not observed as the
intermediate, i.e. its signals appeared only when the signals of
the K[ArMnI(CO)4] product were already visible in the spec-
trum (Fig. S5 of the ESI†). Yet, this alternative possibility of
direct elimination of CO from K[ArC(O)MnI(CO)4] seems less
likely. DFT calculations showed that the barrier for the CO
elimination from Na[(η6-C6H5C(O)MnI(CO)4)Cr(CO)3] is much
higher (32.9 kcal mol−1) than the barrier for elimination of
NaI (19.8 kcal mol−1).k Moreover, the reaction of [Mn(CO)5Br]
with [(C6H5Li)Cr(CO)3] in the presence of P(OMe)3 was
reported to give the product of bromide (not CO) substitution
in the intermediate bromo(acyl)manganate, i.e. [cis-((MeO)3P)
Mn(CO)4(η6-C6H5C(O))Cr(CO)3].23,24
The K[ArMnI(CO)4] complex was not isolated and therefore
was characterized in solution with spectroscopic methods (IR,
13C NMR and HR ESI MS). However, it was observed that the
kBoth computational model reactions lead to the intermediate structures with
η2-coordination of the acyl group. The calculations were performed using the
DFT method with a PBE functional21 and a triple-ζ all-electron basis set, includ-
ing polarization functions, TZ2P using the PRIRODA program package.22
Fig. 1 Resonance with
metallates.
a
metal carbene structure for iodo(aryl)
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recorded on a Thermo Nicolet IR-200 spectrometer in THF in a
0.2 mm CaF2 cell. High resolution mass spectra (HR MS) were
recorded on the Bruker micrOTOF II instrument using electro-
spray ionization (ESI). The measurements were performed in
negative ion mode for anionic complexes and in positive ion
mode for neutral complexes (3200 V); external or internal cali-
bration was done with an Electrospray Calibrant Solution
(Fluka).
All operations with metal carbonyl anion salts were per-
formed in “all-fused” glassware using vacuum-line techniques.
Break-seal ampoules were used for the transfer of substances.
Potassium salts of metal carbonyl anions were obtained quan-
titatively (95–98%) by reductive cleavage of the corresponding
dimers [M(CO)nL]2 with excess of the NaK2.8 alloy (0.15 ml per
1 mmol of dimer) in THF. Na[Re(CO)5] was prepared by the
reduction of Re2(CO)10 with 0.5% NaHg (30–50% excess) and
purified by the low temperature crystallization from THF.
The dicarbonyl(η5-pentamethylcyclopentadienyl)iron dimer
was prepared by the modified literature procedure by the reac-
tion of pentamethylcyclopentadien with [Fe(CO)5] (1 : 2 molar
ratio) in refluxing xylene.32
Fig. 2 Molecular
structure
of
[Et4N][(η6-C6H5ReI(CO)4)Cr(CO)3].
Selected bond distances (Å) and angles (°): Re1–I1 2.8321(3), Re1–C1
2.214(3), Re1–C12 2.007(4), Re1–C13 1.899(4), Re1–C10 1.978(5), Cr1–
C1 2.321(3), C1–C2 1.436(5), C2–C3 1.401(5), Cr1–C4 2.238(4), Cr1–C7
1.824(4), C11–Re1–C12 172.9(1), C13–Re1–I 177.2(1), C12–Re1–C1–C2
51.7(2).
NMR spectroscopy (1H and 13C) was used as a primary tool
for the analysis of the reaction mixtures usually combined
with the IR spectra in the metal carbonyl stretching region
(1550–2200 cm−1). Samples of the reaction mixture were trans-
ferred under vacuum into thin-walled glass tubes (∼3.5 mm
diameter) which were sealed-off with flame and placed into
standard NMR tubes containing acetone-d6 for the lock signal.
Product yields were determined by the integration of the
1H NMR spectra of the reaction solutions containing an
internal standard (durene). The signals were referenced to
the individual products by comparison with the spectra of the
isolated compounds or literature data.
There is no significant shortening of the Re1–C1aryl bond
(2.214 Å) in comparison with the known rhenium σ-aryl com-
plexes (2.22–2.23 Å),28 and it is significantly longer than that
found in rhenium carbene complexes (2.09–2.13 Å).29–31
However, the contribution of metal carbene resonance struc-
ture (Fig. 1) can be traced in the slight elongation of C1–C6
(1.435 Å) and C1–C2 (1.424) bonds adjacent to rhenium, com-
pared to 1.409 Å average for the other four C–C bonds in the
aromatic ring and a slight slipping of the Cr(CO)3 unit away
from C1 by 0.08 Å.
[(η6-C6H5I)Cr(CO)3] was prepared according to the pub-
lished procedure33 by metallation of [(η6-C6H6)Cr(CO)3] with
n-BuLi in THF and subsequent quenching of the resulting
aryllithium with iodine. 1H NMR (THF, 400.13 MHz), δ: 5.77
(m, 2H), 5.40 (m, 3H). 13C NMR (THF, 100.6 MHz), δ: 233.39
Conclusions
The reactions of the iodobenzene Cr(CO)3 π-complex with
carbonylmetallates show an illustrative example of halogenophilic
attack in nucleophilic aromatic substitution. Depending on
the carbonylmetallate anion, the final product of the reaction
may be the σ-aryl complex (with K[(C5Me5)Fe(CO)2]), the iodo
(acyl)rhenate anion (with Na[Re(CO)5]) or the iodo(aryl)manga-
nate anion (with K[Mn(CO)5]), but in all these cases the reac-
tion proceeds via initial attack of the carbonylmetallate anion
at halogen in [(η6-iodobenzene)Cr(CO)3]. Thus, the halogen-
ophilic pathway of nucleophilic substitution is common for
aryl halides with different types of activation – polyfluorinated
and π-coordinated.
(CO), 94.39 (Cquat), 101.41, 95.24, 91.61 (CH). IR (THF), ν/cm−1
1901 vs (ε = 4130), 1973 vs (ε = 3830).
:
Reactions of [(η6-haloarene)Cr(CO)3] with K[(η5-C5R5)Fe(CO)2]
(R = H, CH3)
Reactions were performed by adding haloarene (0.2 mmol) to
a THF solution of carbonylmetallate (0.2 mmol in 3 ml THF)
prepared in situ by the reduction of the dimer with NaK2.8
.
Product yields determined by 1H NMR are given in Table 1.
The nucleophilic substitution product was isolated by column
chromatography on silica gel (Merck 60) using petroleum
ether–CH2Cl2, 2 : 3 as the eluent. [(η6-(C5Me5)(CO)2FeC6H5)-
Cr(CO)3], 1H NMR (THF, 400.13 MHz), δ: 5.27 (m, 4H), 5.14 (m,
1H), 1.71 (s, 15H). 13C NMR (THF, 100.6 MHz), δ: 235.88 (3CO),
Experimental
General
1H NMR (400.13 MHz) and 13C NMR (100.61 MHz) spectra 216.97 (2CO), 137.30 (ipso-Ar), 107.14, 96.79, 90.96 (CH), 97.31
were obtained on a Bruker Avance spectrometer at 22 °C (ipso-Cp*), 9.55 (CH3). IR (THF), ν/cm−1: 1873 vs, 1950 vs, 1959
and referenced to the signals of the solvent. IR spectra were vs, 2011 vs. HR ESI MS, m/z (relative intensity, %): 498.9683
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[M + K]+ (50%), 482.9945 [M + Na]+ (100%). Calcd for 100.6 MHz), δ: 235.51 (CO), 210.1 br (CO), 130.4 (Cquat), 108.87
C21H20CrFeKO5 498.9702, for C21H20CrFeNaO5 482.9963.
(2C), 95.95 (2C), 93.24 (1C) (CH). IR (THF), ν/cm−1: 2123 m,
2065 w, 2027 vs, 2009 sh (Mn(CO)4), 1955 vs, 1878 vs (Cr(CO)3).
Calcd for C14H5CrMnO8: C 41.20, H 1.23. Found: C 41.55,
Reaction of [(η6-C6H5I)Cr(CO)3] with Na[Re(CO)5]
Reaction of [(η6-C6H5I)Cr(CO)3] (24 mg, 0.071 mmol) with H 1.48. ESI MS, m/z (relative intensity, %): 388 [M − 3CO,
Na[Re(CO)5] (0.311 g of THF solution, 0.0648 mmol) produced +CH3CN, +Na]+ (100%), 338 [M − 4CO, +CH3CN, +H]+ (60%),
a single product, quantitatively formed in solution, Na[(η6- 332 [M − 5CO, +CH3CN, +Na]+ (30%).
C6H5C(O)Re(CO)4I)Cr(CO)3]. 1H NMR (THF, 400.13 MHz), δ:
5.82 (m, 2H), 5.49 (m, 3H). 13C NMR (THF, 100.6 MHz), δ:
259.58 (1CO), 233.95 (3CO), 189.11 (2CO), 188.45 (1CO), 187.38
Crystal structure determination of the complex [Et4N]-
[(η6-C6H5Re(CO)4I)Cr(CO)3]
The crystal of 0.10 × 0.12 × 0.15 mm3 (C21H25CrINO7Re, M =
(1CO), 122.05 (Cquat), 94.74 (1C), 94.63 (2C), 92.98 (2C) (CH). IR
(THF), ν/cm−1: 1894 vs, 1915 s, 1967 sh, 1979 vs, 2084 m. IR
768.52) is monoclinic, space group P21/n, at T = 100 K: a =
(THF + 18-crown-6), ν/cm−1: 1890 vs, 1912 s, 1966 vs, 1982 vs,
7.5063(2) Å, b = 29.7019(8) Å, c = 11.2833(3) Å, β = 95.6170(10)°,
V = 2503.55(12) Å3, Z = 4, dcalc = 2.039 g cm−3, F(000) = 1464,
μ = 6.537 mm−1. 32 904 total reflections (7288 unique reflec-
tions, Rint = 0.039) were measured on a three-circle Bruker
APEX-II CCD diffractometer (λ(MoKα)-radiation, graphite
monochromator, φ and ω scan mode, 2θmax = 60°) and cor-
rected for absorption using the SADABS program (Tmin = 0.441;
Tmax = 0.561).34 The structure was determined by direct
methods and refined by the full-matrix least squares technique
on F2 with anisotropic displacement parameters for non-
hydrogen atoms. All hydrogen atoms were placed in calculated
positions and refined within the riding model with fixed
isotropic displacement parameters [Uiso(H) = 1.5Ueq(C) for the
CH3-groups and Uiso(H) = 1.2Ueq(C) for the other groups]. The
final divergence factors were R1 = 0.029 for 6493 independent
reflections with I > 2σ(I) and wR2 = 0.064 for all independent
reflections, S = 1.002. All calculations were carried out using
the SHELXTL program.35
2082 m. HR ESI MS, m/z (relative intensity, %): 554.8174 [M −
4CO]− (60%), 526.8222 [M − 5CO]− (80%), 498.8275 [M −
6CO]− (100%). Calcd for C10H5CrIO4Re 554.8196, for
C9H5CrIO3Re 526.8246, for C8H5CrIO2Re 498.8298. When the
THF solution of the iodo(acyl)rhenate complex was reanalyzed
by NMR after standing for 6 months at room temperature its
main component was another complex, Na[(η6-C6H5Re(CO)4I)
Cr(CO)3]. 1H NMR (THF, 400.13 MHz), δ: 6.05 (m, 2H), 5.12 (m,
3H). 13C NMR (THF, 100.6 MHz), δ: 237.57 (3CO), 189.95
(2CO), 189.31 (1CO), 188.45 (1CO), 129.81 (Cquat), 113.41,
96.37, 92.14 (CH). This iodo(aryl)rhenate was isolated in the
form of [Et4N]+ salt using a modified literature procedure.10
THF was replaced by an equal volume (0.2 ml) of degassed
water, the turbid solution obtained was filtered, and the
product precipitated by the addition of [Et4N]I (20 mg in
0.1 ml H2O) in the form of yellowish oil, which soon solidified
and was dried in a vacuum. [Et4N][(η6-C6H5Re(CO)4I)Cr(CO)3],
IR (THF), ν/cm−1: 1861 s, 1942 s (Cr(CO)3), 1913 s, 1965
vs, 1980 vs, 2081 m (Re(CO)4). Crystals suitable for X-ray
diffraction analysis were grown by slow diffusion of petroleum
ether into the solution of the complex in CH2Cl2.
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Center, CCDC 999498.
Reaction of [(η6-C6H5I)Cr(CO)3] with K[Mn(CO)5]
Acknowledgements
Reactions were performed in THF on the same 0.1 mmol scale
as with other carbonylmetallates, the 1H NMR spectroscopic
product yields are given in Table 2. The neutral Mn(CO)5 σ-aryl
complex was isolated by column chromatography on silica gel
(Merck 60) using petroleum ether–CH2Cl2, 2 : 1 (increasing to
1 : 2) as the eluent. K[(η6-C6H5Mn(CO)4I)Cr(CO)3]. 1H NMR
(THF, 400.13 MHz), δ: 6.02 (m, 2H), 5.14 (m, 2H), 5.10 (m, 1H).
13C NMR (THF, 100.6 MHz), δ: 237.42 (3CO), 224.9 br (1CO),
217.5 br (2CO), 216.1 br (1CO), 137.86 (Cquat), 112.82, 95.50,
91.95 (CH). IR (THF), ν/cm−1: 1865 vs, 1942 vs (Cr(CO)3), 1921
Financial support of this work by the Program of the President
of the Russian Federation for the State Support of Leading
Research Schools (grant no. HIII- 2783.2014.3) and the
Russian Academy of Sciences Program 1-OX is gratefully
acknowledged.
Notes and references
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