Arene exchange in the ruthenium-naphthalene complex [CpRu(C 10H8)]+

Article abstract of DOI:10.1002/ejic.201100928

Substitution of the naphthalene ligand in [CpRu(C₁₀H ₈)]⁺ (1; Cp = cyclopentadienyl ligand) by other arenes occurs upon heating or visible-light irradiation and gives complexes [CpRu(arene)]⁺ [arene = C₆

Full text of DOI:10.1002/ejic.201100928

FULL PAPER
DOI: 10.1002/ejic.201100928
Arene Exchange in the Ruthenium–Naphthalene Complex [CpRu(C10H8)]+
Dmitry S. Perekalin,[a] Eduard E. Karslyan,[a] Pavel V. Petrovskii,[a]
Alexandra O. Borissova,[a] Konstantin A. Lyssenko,[a] and Alexander R. Kudinov*[a]
Keywords: Ruthenium / Cyclopentadienyl ligands / Arene ligands / Naphthalene
Substitution of the naphthalene ligand in [CpRu(C10H8)]+ (1;
Cp = cyclopentadienyl ligand) by other arenes occurs upon
heating or visible-light irradiation and gives complexes
[CpRu(arene)]+ [arene = C6HnMe6–n, C6H5OH, C6H5OMe,
C6H4(OMe)2, indene, 2,2-paracyclophane] in 70–90% yield.
The reaction rate increases with coordinating ability of the
solvent, CH2Cl2 Ͻ THF/CH2Cl2 Ͻ Me2CO, and counterion,
[B(3,5-(CF3)2C6H3)4]– Ͻ PF6 Ͻ BF4 Ͻ CF3SO3–. Acceptor or
bulky substituents in the incoming arene slow down the ex-
change. Complexes with acceptor arenes C6H5COMe,
C6H5COOH, and C6H4(COOH)2 were obtained by the ex-
change reaction in water. Complexes [CpRu(η6-
cycloheptatriene)]+ and [CpRu(η6-cyclooctatetraene)]+ were
obtained by irradiation of 1 with the corresponding cyclic
polyenes. A similar reaction with α-phellandrene is ac-
companied by dehydrogenation to give [CpRu(cymene)]+.
Cation 1 reacts with 2-naphthoic acid anion to give the zwit-
terionic complexes [CpRu]+[C10H7COO]– in which the
[CpRu]+ fragment coordinates either at the substituted or un-
substituted ring. Upon protonation and subsequent irradia-
tion, both isomers convert into [CpRu(C10H7COOH)]+ in
which the metal atom coordinates only to the unsubstituted
ring. The structures of [CpRu(p-xylene)][PF6], [CpRu(2,2-
paracyclophane)][PF6], [CpRu(C6H5COOH)][BF4], and [CpRu-
(cymene)][BPh4] were determined by X-ray diffraction.
–
–
other cationic complexes [CpRuL3]+ (L = phosphane, diene,
diimine).[10] We have found that 1 reacts with halide anions
in the presence of cyclooctadiene or norbornadiene to af-
ford half-sandwich compounds [CpRu(diene)X].[11] Treat-
ment of 1 with cyclopentadienes gives ruthenocenes,[12]
whereas treatment with tricarbollide anions produces ru-
thenacarboranes.[13] Herein we describe the arene exchange
in 1 to give sandwich complexes [CpRu(arene)]+.[14]
Introduction
(Cyclopentadienyl)ruthenium sandwich compounds at-
tract considerable attention due to their high chemical sta-
bility and variety of potential applications. In particular,
arene complexes [CpRu(arene)]+ have been used for acti-
vation of aromatic nucleophilic substitution,[1] synthesis of
biphenyl ether peptides,[2] and functionalization of aromatic
amino acids[3] and steroids.[4] Substituted ruthenocenes
[CpRuCpЈ] were recently employed as ligands[5] and antitu-
mor agents.[6] The high chemical stability of ruthenium
sandwich compounds allowed a number of triple-decker
complexes [CpRu(ring)RuCp]+ (ring = C5Me5, C9H7, P5,
C5B2Me6H, and so on) with various bridging ligands to be
synthesized.[7]
A common approach to the (cyclopentadienyl)ruthenium
complexes is based on substitution of the labile acetonitrile
ligands in the [CpRu(MeCN)3]+ cation.[8] This precursor
was first synthesized by UV irradiation of the benzene com-
plex [CpRu(C6H6)]+ in acetonitrile.[8a] Recently, Kündig and
Monnier suggested a convenient procedure for preparation
of [CpRu(MeCN)3]+ through replacement of the naphth-
alene ligand in [CpRu(C10H8)]+ (1) by MeCN.[9] Hinter-
mann et al. have reported that 1 can be also converted into
Results and Discussion
Thermal Arene Exchange
Arene exchange (the substitution of one arene ligand for
another) is one of the most important reactions of transi-
tion-metal–arene complexes.[15] It proceeds under thermal
or photochemical conditions and was studied in detail for
various chromium,[16] manganese,[17] iron,[18] cobalt,[19] mo-
lybdenum,[20] ruthenium,[21] rhodium,[22] and iridium[23]
compounds. It was shown that the naphthalene ligand is
more readily substituted than benzene due to the facile η6
Ǟ η4 ring slippage, which decreases the activation energy
of the nucleophilic attack at the metal center.[24]
We found that the cationic naphthalene complex 1 (as
–
PF6 salt) reacts with benzene (5 equiv.) in 1,2-dichloro-
[a] A. N. Nesmeyanov Institute of Organoelement Compounds,
Russian Academy of Sciences,
ethane heated at reflux to give 2a with 70% conversion in
6 h (Scheme 1). An analogous reaction with sterically hin-
dered 1,2,4,5-tetramethylbenzene affords 2d with only 10%
conversion in 6 h. The addition of acetonitrile (30 equiv.)
119991 Moscow, Russian Federation
E-mail: arkudinov@ineos.ac.ru
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100928.
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enables 100% conversion in both cases. Presumably, the re-
Similar reactions of 1 with cycloheptatriene and cyclooc-
action is accelerated due to the formation of the labile inter- tatetraene afford the η6-polyene complexes 3 and 4
mediate [CpRu(MeCN)3]+. By using MeCN as a catalyst, (Scheme 3). Interestingly, the irradiation of 1 with α-phell-
complexes with alkylbenzenes 2a–e were synthesized in 70– andrene is accompanied by dehydrogenation to give the ar-
80% yield.
ene complex [CpRu(cymene)]+ (2n). Analogous CH acti-
vation was observed previously in reactions of [Cp*Ru-
(OMe)]2 with cyclohexadienes to give [Cp*Ru(arene)]+ cat-
ions.[26] It was also observed during the preparation of
[{(arene)RuCl2}2] from RuCl3·xH2O and cyclohexa-
dienes.[27]
Scheme 1. Thermal arene exchange in 1.
Photochemical Arene Exchange
Gill and Mann have shown that the benzene ligand in
cation 2a can be replaced by other ligands (MeCN, phos-
phites, and so on) under UV irradiation at λmax
=
320 nm.[8a] Unlike 2a, the naphthalene complex 1 absorbs
in the visible region[24a] at λmax = 364 nm, thereby suggest-
ing the possibility of the arene displacement under visible-
light irradiation. Examples of arene displacement induced
by visible light were previously described for iron[18] and
Scheme 3. Reactions of 1 with cyclic polyenes.
To investigate the effect of substituents on the arene ex-
cobalt[19] complexes. We found that the photochemical reac- change, we have carried out competitive experiments. The
–
tion of 1 (as PF6 salt) with benzene (5 equiv.) in CH2Cl2 arene exchange in 1 was found to slow down in the se-
gives 2a with 10% conversion after 6 h irradiation (650 W). quence: 1,4-C6H4(OMe)2 Ͼ 1,4-C6H4Me2 Ͼ C6H6 Ͼ 1,3,5-
The conversion increases with coordination ability of the C6H3Me3 Ͼ 1,2,4,5-C6H2Me4 ϾϾ C6Me6. This sequence
counterion of 1 in the order [B(3,5-(CF3)2C6H3)4]– (3%) Ͻ can be explained by the conflicting influence of electronic
PF6– (10%) Ͻ BF4– (52%) Ͻ CF3SO3– (66%). The reaction and steric effects. In particular, due to the favorable donor
is more effectively accelerated by coordinating solvents: effect of two methyl substituents, p-xylene reacts faster than
100% conversion of 1[PF6] into 2a[PF6] was reached after benzene. However, in the case of mesitylene, unfavorable
12 h of irradiation in THF/CH2Cl2 (1:1) or after 6 h in ace- steric hindrance of three methyl groups overcomes the fa-
tone.[25] Under the latter conditions, complexes 2a–d,f–j vorable donor effect and therefore it reacts slower than
were synthesized in 70–90% yield (Scheme 2).
benzene. Similar rate dependence was previously observed
for iridium complexes [(η4-1,5-cyclooctadiene)Ir(η6-
arene)]+.[23a] For steric reasons, the reaction of 1 with hexa-
methylbenzene is very slow and reaches only 25% conver-
sion after 30 h of irradiation in acetone. Steric hindrance
also slows down arene exchange for the methylated ana-
logue of 1, cation [Cp*Ru(C10H8)]+. Its reaction with p-xy-
lene proceeds 15 times slower than that of 1.
The acceptor substituents in the incoming arene inhibit
the exchange. In particular, no reaction occurs between 1
and 1,4-dichlorobenzene under both thermal and photo-
chemical conditions in C2H4Cl2 or acetone. We found, how-
ever, that irradiation of 1 with water-soluble, electron-de-
ficient arenes (acetophenone, benzoic acid, phthalic acid) in
aqueous solution gives the corresponding complexes 2k–m.
Presumably, the arene exchange is facilitated due to the high
polarity of water. This method was also successfully used
Scheme 2. Photochemical arene exchange in 1.
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Arene Exchange in [CpRu(C10H8)]+
for the synthesis of ruthenium complexes with aromatic to the unsubstituted ring to give 7 as the sole product. The
amino acids and small peptides under biological condi- reaction is reversible: deprotonation of 7 and further irradi-
tions.[3d]
ation gives the mixture of 6a,b in the same 3:1 ratio. This
process is a rare example of pH-controlled haptotropic re-
arrangement.[29]
Reactions of 1 with Substituted Naphthalenes
The substitution of the naphthalene ligand in 1 by benz-
ene derivatives under visible-light irradiation is irreversible
since the resulting complexes 2 do not absorb in the visible
region (see above). To study a reversible process, we have
carried out the reaction between 1 and the 1-naphthyl-
ammonium cation (Scheme 4). The formation of the iso-
meric cations 5a,b from 1 should be unfavorable on account
+
of the destabilizing effect of the electron-withdrawing NH3
group. Indeed, no naphthalene exchange occurs in nitro-
methane solution. However, in aqueous solution, the equi-
librium is shifted towards the formation of 5a,b due to pre-
cipitation of naphthalene. In particular, 6 h irradiation of 1
with 3 equiv. of 1-naphthylammonium cation in the pres-
ence of HBF4 in D2O gives a mixture of 1, 5a, and 5b in a
5:10:2 ratio according to 1H NMR spectroscopy.[28] Further
irradiation of the mixture does not change this ratio,
thereby suggesting that the equilibrium point was reached.
The addition of CD3OD to the mixture increases the solu-
bility of naphthalene and converts 5a,b back to 1. On the
contrary, the repeated extraction of naphthalene by petro-
leum ether from the reaction mixture allows one to achieve
quantitative conversion of 1 into 5a,b. However, we were
Scheme 5. The pH-controlled haptotropic rearrangement.
–
unable to isolate pure complexes 5a,b {as salts with BF4 ,
–
PF6 , or [Co(C2B9H11)2]– anion} because of their fast de-
X-ray Structures
composition in the solid state.
The structures of the arene complexes [CpRu(1,4-
Me2C6H4)][PF6] (2b[PF6]), [CpRu(2,2-paracyclophane)]-
[PF6] (2g[PF6]), [CpRu(C6H5COOH)][BF4] (2l[BF4]), and
[CpRu(cymene)][BPh4] (2n[BPh4]) were established by X-ray
diffraction (Figures 1, 2, 3, and 4). The Ru···C5(plane) dis-
tances (1.807–1.817 Å) are similar for all the compounds
and are close to that in the starting naphthalene cation 1
Scheme 4. Equilibrium reaction of 1 with 1-naphthylammonium
cation.
Irradiation of 1 with the potassium salt of 2-naphthoic
acid anion in water gives a 3:1 equilibrium mixture of the
isomeric complexes 6a,b according to 1H NMR spec-
troscopy (Scheme 5). Upon protonation by HBF4 and sub-
sequent irradiation, they both convert into the 2-naphthoic
acid complex 7, which was isolated in 68% yield. Appar-
ently, the COOH group is more electron withdrawing than
Figure 1. The molecular structure of cation 2b with ellipsoids at
the 50% probability level. Only one of two independent molecules
is shown. All hydrogen atoms are omitted for clarity. Selected in-
teratomic distances [Å]: Ru1–C1 2.168(3), Ru1–C2 2.167(2), Ru1–
C2A 2.167(2), Ru1–C3 2.166(2), Ru1–C3A 2.166(2), Ru1–C4
2.1997(19), Ru1–C4A 2.1997(19), Ru1–C5 2.2202(19), Ru1–C5A
COO–, and therefore the [CpRu]+ fragment in 6b migrates 2.2202(19), Ru1–C6 2.1937(19), Ru1–C6A 2.1937(19).
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(1.811 Å).[10,14b] The Ru···C6(plane) distances in cations
2b,l,n are also similar (1.690–1.705 Å), being somewhat
shorter than that in 1 (1.719 Å). The CO2H group in 2l
forms typical intermolecular O···HO hydrogen bonds with
an O···O distance of 2.591 Å.
Figure 4. The molecular structure of cation 2n with ellipsoids at the
50% probability level. All hydrogen atoms are omitted for clarity.
Selected interatomic distances [Å]: Ru1–C1 2.178(2), Ru1–C2
2.186(2), Ru1–C3 2.195(3), Ru1–C4 2.182(2), Ru1–C5 2.178(2),
Ru1–C6 2.205(2), Ru1–C7 2.204(2), Ru1–C8 2.249(2), Ru1–C9
2.221(2), Ru1–C10 2.205(2), Ru1–C11 2.224(3).
rings in 2g (0.158–0.162 Å) and for the free ligand
(0.157 Å). As a consequence, the Ru–C(bridgehead) bonds
(avg. 2.339 Å) are longer than other Ru–C(arene) bonds
(avg. 2.201 Å). The mean planes of the arene rings in 2g are
almost parallel to each other (1.9°) and are separated by
2.925 Å, which is a bit shorter than that for the paracyclo-
phane (2.994 Å). This shortening is generally attributed to
the acceptor effect of metal atom, which decreases the elec-
tron density between the aromatic decks and therefore re-
duces their repulsion.[31] The perimeter of the coordinated
C6 ring is 0.152 Å larger than that of the noncoordinated
one. Overall, the main structural features of 2g are similar
to those of other ruthenium paracyclophane complexes.[32]
Figure 2. The molecular structure of cation 2g with ellipsoids at the
50% probability level. All hydrogen atoms are omitted for clarity.
Selected interatomic distances [Å]: Ru1–C3 2.3367(9), Ru1–C4
2.2079(9), Ru1–C5 2.2053(9), Ru1–C6 2.3400(9), Ru1–C7
2.1979(9), Ru1–C8 2.1928(8), Ru1–C17 2.1733(10), Ru1–C18
2.1954(9), Ru1–C19 2.1966(9), Ru1–C20 2.1782(10), Ru1–C21
2.1751(11).
Conclusion
We have shown that the naphthalene ligand in 1 is substi-
tuted by other arenes under both thermal and photochemi-
cal conditions. This reaction allows one to obtain various
[CpRu(arene)]+ cations starting from the readily available
complex 1. The reaction rate increases with the coordinat-
ing ability of the solvent and counterion. Donor substitu-
ents in the incoming arene also accelerate the reaction.
However, introduction of three or more methyl groups re-
sults in significant steric hindrance and slows down the ar-
ene exchange. Acceptor substituents in the incoming arene
also slow down the reaction and preclude the preparation
of the corresponding [CpRu(arene)]+ complexes in organic
solvents. Nevertheless, complexes with acetophenone, and
Figure 3. The molecular structure of cation 2l with ellipsoids at the
50% probability level. All hydrogen atoms except the one of COOH
are omitted for clarity. Selected interatomic distances [Å]: Ru1–
C1 2.170(2), Ru1–C2 2.164(2), Ru1–C3 2.175(2), Ru1–C4 2.181(2),
Ru1–C5 2.176(2), Ru1–C6 2.182(2), Ru1–C7 2.196(2), Ru1–C8
2.202(2), Ru1–C9 2.208(2), Ru1–C10 2.228(2), Ru1–C11 2.211(2).
Both C6 rings in the paracyclophane cation 2g are signifi- benzoic and terephthalic acid were obtained by using water
cantly deviated from planarity towards a boat conforma- as a solvent presumably due to its high polarity and coordi-
tion. This deviation can be characterized by a single param- nating ability.
eter, namely, the bending angle along the line between the
The photochemical reactions of 1 with 1-naphthylammo-
bridgehead carbon atoms (C3···C6 for the coordinated ring nium cation and 2-naphthoic acid anion are reversible. In
and C11···C14 the noncoordinated one). This angle is equal water, the equilibrium is shifted towards the substituted
to 15.1° for both rings and is close to that in the free para- complexes due to precipitation of naphthalene. The ruthe-
cyclophane (14.9°).[30] The deviation of the bridgehead car- nium coordination occurs predominantly at the unsubsti-
+
bons from the C4 boat planes is also similar for both arene tuted ring because of the acceptor effect of NH3 and
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Arene Exchange in [CpRu(C10H8)]+
1
COO– substituents. The complex with 2-naphthoic acid
anion undergoes haptotropic rearrangement upon proton-
ation and irradiation.
Compound 2d[PF6]: Yield 30 mg (77%). H NMR: δ = 2.37 (s, 12
H, Me), 5.33 (s, 5 H, Cp), 6.34 (s, 2 H, C6H2) ppm. C15H19F6PRu
(445.35): calcd. C 40.45, H 4.30; found C 40.77, H 4.33.
1
Compound 2e[PF6]: Yield 33 mg (80%). H NMR: δ = 2.49 (s, 18
H, Me), 5.18 (s, 5 H, Cp) ppm; cf. ref.[8a]
Experimental Section
[CpRu(arene)][PF6] (2a–d,f–j[PF6]) by Photochemical Arene Ex-
change: A yellow solution of 1[PF6] (44 mg, 0.1 mmol) and arene
(0.5 mmol, excess amount) in acetone (4 mL) was irradiated until
it became colorless (typically 4–8 h). The solvent was evaporated
and the residue was washed several times with Et2O to remove un-
reacted arene and liberated naphthalene. The solid was dissolved in
acetone and filtered through a short alumina column. The resulting
solution was evaporated, and the residue was reprecipitated from
CH2Cl2/Et2O to give white crystalline products. Complex 2h[PF6]
was purified by trituration in Et2O instead of filtration through
alumina column.
General: All reactions were carried out under argon atmosphere in
anhydrous solvents, which were purified and dried using standard
procedures. Isolation of products was conducted in air. Irradiation
was performed in Schlenk tubes with high-pressure mercury vapor
lamps and a phosphor-coated bulb (e.g., Philips HPL Comfort, to-
tal power 650 W). Both tubes and lamps were placed into a vessel
of an appropriate volume covered inside with aluminum foil; cool-
ing was accomplished with running water. The 1H NMR spectra
were measured with a Bruker Avance 400 spectrometer at 25 °C in
[D6]acetone unless otherwise stated. Chemical shifts are given in
ppm relative to the residual signal of the solvent ([D5]acetone, δ =
2.05 ppm).
Compound 2a[PF6]: Yield 27 mg (70%). 2b[PF6]: Yield 40 mg
(95%). 2c[PF6]: Yield 34 mg (80%). 2d[PF6]: Yield 41 mg (93%).
[CpRu(C10H8)][BF4] (1[BF4]): The preparation of 1[BF4] was per-
formed similar to the literature procedure for 1[PF6].[9a] Rutheno-
cene (3.3 g, 14 mmol), naphthalene (18.0 g, 140 mmol), AlCl3
(1.9 g, 14 mmol), and Al powder (200 mg, 7 mmol) were placed
into a round-bottomed flask equipped with magnetic stirring bar.
Dry decalin (100 mL) was added, followed by TiCl4 (0.77 mL,
7 mmol). The resulting deep-red solution was heated for 50 h at
140 °C with stirring. After cooling a mixture of HCl (35%, 20 mL),
H2O2 (30%, 20 mL) and iced water (200 mL) were slowly added.
The resulting mixture was stirred for 15 min, and water phase was
separated. The organic phase was extracted with H2O (10 mL three
times) and discarded. The water layers were combined and filtered
through double paper filter. Aqueous HBF4 (45%, 10 mL) was
added, and the resulting solution was extracted with CH2Cl2
(40 mL five times). Organic layers were combined, dried with
Na2SO4, and evaporated in vacuo. The brown-yellow residue was
dissolved in acetone and passed through a short (10 cm) alumina
column. The solvent was removed in vacuo, and the solid was re-
precipitated from acetone/Et2O to give bright-yellow crystals of
1[BF4]. Yield 3.4 g (64%). Complexes 1[B(3,5-(CF3)2C6H3)4] and
1[CF3SO3] were prepared similarly by addition of Na[B(3,5-(CF3)2-
C6H3)4] or CF3SO3Na instead of aqueous HBF4 during workup.
1H NMR: δ = 5.15 (s, 5 H, Cp), 6.47 (m, 4 H, C10H8), 7.25 (m, 4
H, C10H8), 7.73 (m, 4 H, C10H8), 7.89 (m, 4 H, C10H8) ppm; cf.
ref.[9a]
1
Compound 2f[PF6]: Yield 24 mg (67%). H NMR: δ = 3.40 (m, 2
H, CH2), 5.29 (s, 5 H, Cp), 6.20 (m, 2 H), 6.78 (m, 1 H), 6.90 (m,
3 H) ppm; cf. ref.[33]
1
Compound 2g[PF6]: Yield 45 mg (87%). H NMR: δ = 3.04 (m, 4
H, CH2), 3.30 (m, 4 H, CH2), 5.17 (s, 5 H, Cp), 5.62 (s, 4 H, C6H4),
6.91 (s, 4 H, C6H4) ppm; cf. ref.[8a]
Compound 2h[PF6]: Yield 25 mg (72%). 1H NMR: δ = 5.41 (s, 5 H,
Cp), 5.99 (t, J = 5.6 Hz, 1 H), 6.20 (t, J = 5.6 Hz, 2 H), 6.28 (d, J
= 6 Hz, 2 H) ppm; cf. ref.[34]
1
Compound 2i[PF6]: Yield 26 mg (73%). H NMR: δ = 3.88 (s, 3 H,
OMe), 5.52 (s, 5 H, cp), 6.13 (m, 1 H, C6H5), 6.29 (m, 2 H, C6H5),
6.43 (m, 2 H, C6H5) ppm; cf. ref.[35]
1
Compound 2j[PF6]: Yield 30 mg (78%). H NMR: δ = 3.84 (s, 6 H,
OMe), 5.55 (s, 5 H, Cp), 6.33 (s, 4 H, C6H4) ppm. C13H15F6O2PRu
(449.29): calcd. C 34.75, H 3.37; found C 34.80, H 3.62.
Compound 2k,l[BF4]:
A yellow solution of 1[BF4] (38 mg,
0.1 mmol) and arene (0.4 mmol) in water (4 mL) and EtOH
(0.1 mL, enhances solubility of arene) was irradiated until it be-
came colorless (12 h). The solvent was evaporated, and the residue
was washed several times with Et2O to remove unreacted arene and
liberated naphthalene. The solid was reprecipitated from CH3NO2/
Et2O to give white crystalline products.
Compound 2k[BF4]: Yield 16 mg (43%). 1H NMR: δ = 2.67 (s, 3
H, Me), 5.64 (s, 5 H, Cp), 6.59 (m, 3 H, C6H5), 6.91 (m, 2 H, C6H5)
ppm; cf. ref.[36]
[CpRu(arene)][PF6] (2a[PF6]–2e[PF6]) by Thermal Arene Exchange:
A
yellow solution of 1[PF6] (44 mg, 0.1 mmol) and arene
(0.5 mmol, excess amount) in 1,2-dichloroethane (5 mL) and
MeCN (0.1 mL) was heated to reflux until it became colorless (typ-
ically 6–8 h; 24 h for reaction with C6Me6). The solvent was evapo-
rated, and the residue was washed several times with Et2O to re-
move unreacted arene and liberated naphthalene. The solid was
dissolved in acetone and filtered through a short alumina column.
The resulting solution was evaporated and the residue was repre-
cipitated from CH2Cl2/Et2O to give white crystalline products.
1
Compound 2l[BF4]: Yield 36 mg (96%). H NMR (D2O): δ = 5.33
(s,
5 H, Cp), 6.23 (m, 3 H), 6.62 (m, 2 H) ppm.
C12H11BF4O2Ru·2H2O (411.12): calcd. C 35.06, H 3.68; found C
35.47, H 3.94; cf. ref.[34]
Compound 2m[BPh4]: A solution of 1[BF4] (19 mg, 0.05 mmol) and
o-phthalic acid (50 mg, 0.3 mmol) in water (4 mL) and EtOH
(0.1 mL) was irradiated 18 h. An excess amount of water solution
of NaBPh4 was added to the reaction mixture to give white precipi-
tate. The mixture was extracted with CH2Cl2 (precipitated product
dissolves in CH2Cl2), organic layer was dried with Na2SO4 and the
solvents evaporated in vacuo. The residue was reprecipitated from
acetone/Et2O to give 2m[BPh4] as white solid. Yield 33 mg (50%).
1H NMR (D2O): δ = 5.52 (s, 5 H, Cp), 6.54 (m, 2 H, C6H4), 6.78
(m, 4 H, BPh4), 6.92 (m, 8 H, BPh4), 6.99 (m, 2 H, C6H4), 7.34 (m,
Compound 2a[PF6]: Yield 27 mg (70%). 1H NMR: δ = 5.54 (s, 5 H,
Cp), 6.34 (s, 6 H, C6H6) ppm; cf. ref.[8a]
Compound 2b[PF6]: Yield 29 mg (84%). 1H NMR: δ = 2.37 (s, 6 H,
Me), 5.46 (s, 5 H, Cp), 6.30 (s, 4 H, C6H4) ppm. C13H15F6PRu
(417.29): calcd. C 37.42, H 3.62; found C 38.11, H 3.66.
Compound 2c[PF6]: Yield 26 mg (74%). 1H NMR: δ = 2.39 (s, 9 H,
Me), 5.41 (s, 5 H, Cp), 6.23 (s, 3 H, C6H3) ppm. C14H17F6PRu 8 H, BPh4) ppm. C37H31BO4Ru·2H2O (651.52): calcd. C 64.63, H
(431.32): calcd. C 38.99, H 3.97; found C 39.08, H 3.72. 5.13; found C 64.16, H 4.95.
Eur. J. Inorg. Chem. 2012, 1485–1492
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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A. R. Kudinov et al.
FULL PAPER
Compound 3,4[PF6]: A yellow solution of 1[PF6] (44 mg, 0.1 mmol)
and cycloheptatriene or cyclooctatetraene (0.3 mmol, excess
amount) in acetone (4 mL) was irradiated for 6 h. The solvent was
evaporated and the residue was reprecipitated from CH2Cl2/Et2O
to give white crystalline products.
NMR Spectroscopy Experiments for Competitive Arene Exchange:
A solution of 1[PF6] (4.4 mg, 0.01 mmol) and two arenes (0.1 mmol
of each) in [D6]acetone (0.5 mL) was irradiated in an NMR spec-
troscopy tube for 1–3 h (100% conversion was not reached). After
irradiation the 1H NMR spectra were recorded, and the ratio of
the complexes 2 was determined by integration of signals due to
Cp and coordinated arene. The ratio established: 2a/2b = 1:1.35;
2a/2c = 2.18:1; 2b/2c = 2.84:1; 2b/2d = 3.98:1; 2d/2e = 30:1.
Compound 3[PF6]: Yield 32 mg (79%). 1H NMR: δ = 1.31 (m, 1 H,
CH2), 3.05 (m, 1 H, CH2), 4.10 (m, 2 H), 5.60 (s, 5 H, Cp), 5.69
(m, 2 H), 6.82 (m, 2 H) ppm; cf. ref.[33]
NMR Spectroscopy Experiment for 5a,b: A solution of 1[BF4]
(3.8 mg, 0.01 mmol) and [1-C10H7NH3]BF4 (6.9 mg, 0.03 mmol) in
D2O (0.5 mL) and HBF4 (40% aq. solution, 0.01 mL) was irradi-
Compound 4[PF6]: Yield 29 mg (71%). 1H NMR: δ = 5.15 (m, 2
H), 5.75 (s, 5 H, Cp), 6.05 (m, 4 H), 6.99 (m, 2 H) ppm; cf. ref.[33]
1
ated in NMR spectroscopy tube for 6 h. After irradiation, the H
Compound 2n[BPh4]: A suspension of 1[BF4] (38 mg, 0.1 mmol),
K2CO3 (69 mg, 1 mmol) and α-phellandrene (0.2 mL, excess
amount) in CH2Cl2 (3 mL) and THF (3 mL) was irradiated for 6 h.
The solvent was evaporated, residue was washed with Et2O (5 mL)
and dissolved in H2O. Saturated aqueous NaBPh4 was added to
aqueous solution to give a white precipitate. The precipitate was
filtered and reprecipitated from Me2CO/Et2O. Yield 18 mg (49%).
1H NMR: δ = 1.26 (d, J = 7 Hz, 6 H, Me), 2.35 (s, 3 H, Me), 2.77
(st, J = 7 Hz, 1 H, CHMe2), 5.48 (s, 5 H, cp), 6.30 (m, 4 H, C6H4),
6.78 (m, 4 H, BPh4), 6.92 (m, 8 H, BPh4), 7.34 (m, 8 H, BPh4)
ppm; cf. ref.[35a]
NMR spectra were recorded, which indicated the presence of 1/5a/
5b mixture in a 5:10:2 ratio. For 1H NMR spectra, see the Support-
ing Information.
NMR Spectroscopy Experiment for 6a,b: A solution of 7[BF4]
(4 mg) and K2CO3 (10 mg, excess amount) in D2O (0.5 mL) was
irradiated in an NMR spectroscopy tube for 6 h. After irradiation,
1
the H NMR spectra were recorded, which indicated the presence
of 6a,b mixture in a 3:1 ratio. Then HBF4 (40% aq. solution,
0.05 mL, excess amount) was added, and the mixture was irradiated
for 6 h. The 1H NMR spectra indicated the formation of 7[BF4].
1
For H NMR spectra, see the Supporting Information.
Compound 7[BF4]: A solution of 1[BF4] (38 mg, 0.1 mmol) and po-
tassium salt of 2-naphthoic acid (42 mg, 0.2 mmol) in H2O (4 mL)
was irradiated for 6 h. The liberated naphthalene was extracted
with Et2O (3 mL twice) and 40% aqueous HBF4 (0.05 mL) was
added to precipitate the unreacted 2-naphthoic acid, which was fil-
tered off. The solution was then extracted with CH3NO2 (3 mL
three times), the organic fraction was dried with Na2SO4, and the
solvents evaporated in vacuo. The solid residue was washed with
CH2Cl2 (2 mL three times), dissolved in CH3NO2, and crystallized
X-ray Crystallography: Crystals of 2b[PF6], 2g[PF6], 2l[BF4], and
2n[BPh4] suitable for X-ray diffraction were grown by slow dif-
fusion of Et2O into solutions of the complexes in CH2Cl2. X-ray
diffraction data were collected with a Bruker SMART APEX II
diffractometer at 100 K. The structures were solved by direct meth-
ods and refined by full-matrix least-squares against F2 in an aniso-
tropic approximation for non-hydrogen atoms. Crystallographic pa-
rameters for all compounds are given in Table 1. All calculations
were performed using the SHELXTL PLUS 5.0 software.[37]
by slow diffusion of Et2O into solution to give bright yellow crys-
1
tals of 7[BF4]. Yield 29 mg (68%). H NMR (D2O): δ = 4.97 (s, 5 CCDC-832440 (2b[PF6]), 832441 (2g[PF6]), 832442 (2l[BF4]) and
H, Cp), 6.28 (m, 2 H), 7.02 (m, 2 H), 7.73 (d, J = 9.2 Hz, 1 H), 832443 (2n[BPh4]) contain the supplementary crystallographic data
7.88 (dd, J = 9.2, J = 1.6 Hz, 1 H), 8.38 (d, J = 1.6 Hz, 1 H) ppm.
C16H13BF4O2Ru (425.15): calcd. C 45.20, H 3.08; found C 45.00,
H 3.12.
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Table 1. Crystallographic data[a] for 2b[PF6], 2g[PF6], 2l[BF4], and 2n[BPh4].
2b[PF6]
2g[PF6]
2l[BF4]
2n[BPh4]
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C13H15F6PRu
417.29
orthorhombic
Pnma
13.4570(8)
14.0008(8)
15.4823(9)
C21H21F6PRu
519.42
monoclinic
P21/n
7.75480(10)
25.2137(3)
9.39460(10)
94.5744(6)
1831.05(4)
4
1.884
1040
1.008
1.62–55.00
195915
C12H11BF4O2Ru
375.09
monoclinic
P21/n
8.0333(6)
12.9137(10)
12.0314(10)
94.662(2)
1244.00(17)
4
2.003
736
1.306
2.32–29.00
12332
C39H39BRu
619.58
orthorhombic
Pca21
18.3901(15)
9.5136(7)
17.0273(13)
β [°]
V [Å3]
2917.0(3)
8
1.900
1648
1.239
1.96–29.00
22368
4006 (0.0359)
3405
2979.0(4)
4
1.381
1288
0.553
2.14–29.00
17596
7834 (0.0292)
7135
Z
Dcalcd. [gcm–3]
F(000)
μ(Mo-Kα) [mm–1]
θ range [°]
Collected reflections
Independent reflections (Rint
Observed reflections [I Ͼ 2σ(I)]
Parameters
)
23421 (0.0395)
20515
346
3291 (0.0281)
2846
218
202
374
R1 (on F for obsd. reflections)
wR2 (on F2 for all reflections)
GOF
0.0245
0.0569
1.002
0.0400
0.0870
1.000
2.312/–2.658
0.0244
0.0580
1.001
0.726/–0.415
0.0270
0.0569
1.001
Largest diff. peak/hole [eÅ3]
0.829/–0.592
0.414/–0.262
[a] R1 = ∑||Fo| – |Fc||/∑(Fo) for observed reflections; wR2 = {∑[w(F2o – Fc2)2]/∑[w(F2o)2]}0.5 for all reflections.
1490 Eur. J. Inorg. Chem. 2012, 1485–1492
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Arene Exchange in [CpRu(C10H8)]+
P. V. Petrovskii, A. O. Borisova, A. R. Kudinov, Russ. Chem.
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cation giving 5a,b and for haptotropic rearrangements of 7 into
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Acknowledgments
This work was supported by the Russian Foundation for Basic Re-
search (grant number 11-03-01153-a) and Grant for Young Scien-
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Received: September 2, 2011
Published Online: November 23, 2011
1492
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Eur. J. Inorg. Chem. 2012, 1485–1492