SYNTHESIS AND SPECTROSCOPIC STUDIES
503
tallization from a mixture of dichloromethane–n–hep- 5% ammonia solution in water (50 ml), followed by sat-
tane (ratio 1 : 1) furnished a pure sample of the desired urated sodium chloride solution (2 × 50 ml). The solu-
complex in 22% yield. Infrared spectrum of V showed tion was dried over magnesium sulfate and concentrated.
the presence of bands at 1965 and 1920 cm–1 assigned Distillation under reduced pressure afforded I as a color-
to terminal CO stretch and a single band at 1759 cm–1 less oil, (15 g, 100 mmol), 30%. IR spectrum (neat, ν,
assigned to bridging CO stretch. Similar to IV, this pat- cm–1): 2850–2930 s, 1700 s, 1640 s, 1180 m; 1H NMR
tern of peaks together with weak shoulders at 1795 and (CDCl3, δ, ppm): 0.85 (d., 3H), 1.3–2.6 (m, 11 H).
1895 cm–1 is well documented to be characteristic of Mass (m/e (%)):150 (83), 135 (75), 107 (59), 79 (75).
cis-trans isomers of [Cp2Ru(CO)]2(µ-CO)2 dimer V. It
Synthesis of 1,3-dimethyl-4,5,6,7-tetrahydroin-
has been difficult to obtain high quality 1H NMR spec-
dene (II). Methyl magnesium iodide was prepared
tra for V, since even samples prepared from freshly
from methyl iodide (2 g, 15 mmol) and magnesium
crystallized material gave rise to a broad C–H reso-
turnings (0.3 g, 12.5 mmol) in anhydrous diethyl ether.
nances in the 1H NMR spectrum.
The reaction began in a few minutes, as was shown by
Very careful sample preparation was necessary to
prepare a sample from which we were able to obtain a
1H NMR spectrum in which the 1-phenyl-3-methyl-tet-
rahydroindenyl ligand resonances could be assigned,
although, carbonyl resonances were not observed in the
13C NMR spectra. These NMR characteristics may be
due to oxidation or some other decomposition pro-
cesses in solution giving rise to the traces of paramag-
netic impurities or from an equilibrium in solution
between the ruthenium dimer [(Cp2)Ru(CO)]2(µ-CO)2
V and either a paramagnetic 17-electron monomer
[(Cp2)Ru(CO)2] or the 32-electron molecule
[(Cp2)Ru]2(µ-CO)3 and CO. Similar dimer–monomer
equilibria are well documented in groupVI chemistry for
[(η5-C5H5)M(CO)3]2 (M = Cr, Mo, W) and related com-
plexes containing bulky cyclopentadienyl ligands [11].
gentle refluxing of the solvent. The flask was heated for
another 5 min in a water bath (35°C) to complete the
preparation of methyl magnesium iodide. At this point,
the reaction mixture was cooled by the application of
crashed ice and compound I (2 g, 13 mmol) was slowly
added with stirring. During the addition, a green color
developed. After the ketone addition completed, the
mixture was allowed to warm to room temperature and
stirred for 15 h. The unreacted magnesium was filtered
and the solution was quenched with water. The aqueous
layer was extracted with diethyl ether and the combined
organic extracts were dried over magnesium sulfate and
filtered. Aqueous 12 M HCl (0.5 ml) was added to the
ethereal solution and stirred for 2 h. The organic phase
was separated, washed with water and dried over mag-
nesium sulfate. Ethereal solution was filtered, evapo-
rated in vacuo and purified (SiO2, ethyl acetate/petro-
leum ether 1 : 14) to yield a clear green oil (0.97 g,
6.5 mmol) in 45% yield. GC analysis indicated the pres-
ence of several isomers. IR spectrum (CCl4, ν, cm–1):
2850–2950 s, 1560–1590 w, 1375 w, 1450 w. 1H NMR
(CDCl3, δ, ppm): 0.8–2.7 (m, 15 H), 5.2 (m, 1H).
EXPERIMENTAL
All starting materials were obtained from commer-
cial suppliers and used without further purification. All
reactions involving air or moisture sensitive com-
pounds were performed under argon or nitrogen atmo-
spheres. IR spectra were recorded on a Shimadzu 470
Synthesis of 3-methyl-1-phenyl-4,5,6,7-tetrahy-
droindene (III). This ligand was prepared by using
unsaturated ketone I and phenyl magnesium bromide in
a manner analogous to II. The Grignard reagent was
prepared from bromobenzene (0.650 g, 4.14 mmol) and
magnesium turnings (0.399 g, 16.6 mmol) in a similar
way as in II. The reaction was much slower than the
methyl magnesium bromide. The reaction mixture was
kept for an additional 15 min to completion of prepara-
tion, then, via syringe, unsaturated ketone I (2 g,
13 mmol) was added with stirring. The solution was
stirred for 15 h. As in the case of II, work-up and dehy-
dration with aqueous 12 M HCl (0.5 ml) yielded III
(1.34 g) as a red oil in 48% yield. IR spectrum (neat, ν,
cm–1): 3000–3050 w, 2800–2900 s, 1590–1600 w, 695–
1
spectrometer. H NMR spectra were measured on a
Bruker 80 MHz-FT or Varian-500 MHz (DRX-Avance)
spectrometer, chemical shifts are given in ppm (δ) rela-
tive to Me4Si as internal standard. Capillary GC analy-
ses were performed using a Buck Scientific 910 (capil-
lary column MKhT-5, column length: 15 m) and mass
spectra by Mass-QP 1100 EX Shimadzu.
Column chromatography was carried out by using
silica gel 60 GF254 Merck (art No.: 7730, 7733). The
solvents were dried according to the standard methods
prior to use.
Synthesis of 3-methyl-2,3,4,5,6,7-hexahydroind-
8(9)-en-1-one (I). Cyclohexene (27.3 g, 322 mmol)
was added dropwise to a mechanically stirred mixture
of crotonic acid (28.7 g, 333 mmol) and polyphospho-
ric acid (200 g) at 60°C. The mixture was stirred at
1
730 s. H NMR (CDCl3, δ, ppm): 0.89–1.00 (m, 3H),
1.23–2.2 (m, 8H), 5.32 (s, 1H), 7.2–7.6 (m, 5H).
Synthesis of bis(1,3-dimethyl-4,5,6,7-tetrahy-
60°C for 2 h. A solution of 10% NaOH (100 ml) was droindenyl)diruthenium tetracarbonyl (IV). To pre-
added and the slurry stirred for 16 h to facilitate decom- pare [Cp1Ru(CO)]2(µ-CO)2 (IV), tetrahydroinden
position of the polyphosphoric acid. The mixture was ligand II (0.1 g, 0.6 mmol) and Ru3(CO)12 (0.35 g,
extracted with 40–60°C petroleum ether (3 × 100 ml) 0.5 mmol) were refluxed in n-heptane (20 ml) for 24 h,
and the combined organic extracts were washed with without exclusion of the air. The solvent was removed
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 29 No. 7 2003