Mononuclear Indoline Complexes
Organometallics, Vol. 17, No. 5, 1998 981
[(cymene)Ru(η6-indoline)](OTf)26 was formed in 83% yield. The
product was isolated and identified by H NMR spectroscopy.
ligands had completely exchanged with solvent. Resonances
tentatively assigned to [(cymene)Ru(η1-indolinyl)(CD3CN)x]+
were observed: δ 7.46, 7.25, 6.95, 6.81 (4 m, arene H’s of
indolinyl), 6.03, 5.64 (2 d, cymene), 3.43, 2.92 (2 t, NCH2CH2),
1.69 (cymene-Me), 2.74 (sept, CHMe2), 1.2 (d, CHMe2 obscured
by NEt3). Other unidentified resonances were also observed
in the spectrum, including multiplets at δ 7.02, 6.45, 5.48, and
4.08, and resonances for free indoline may also be present in
low intensity. Resonances for indole were observed to grow
over a period of 24 h to give a yield of ca. 60%, while resonances
attributed to the indolinyl complex decreased. No new cymene-
containing ruthenium products were observed at the end of
the reaction, and no ruthenium hydride signals were detected.
In two separate experiments in CD3CN, sodium methoxide
supported on alumina and pyrrolidine were substituted for
triethylamine. Similar formation of indole was observed, but
the nature of the ruthenium products varied with the identity
of the base.
1
Syn th esis of (Cym en e)Ru (η1-in d olin e)Cl2, 2. Complex
1 (0.199 g, 0.271 mmol) was dissolved in 15 mL of tetrahy-
drofuran, and LiCl (0.0620 g, 1.46 mmol) was then added to
the solution. The solution immediately turned orange and was
stirred under N2 for 1 h. After the solvent was removed in
vacuo, the orange solid was redissolved in dichloromethane
and filtered through Celite. The filtrate was evaporated to
give the product as an orange solid. The complex was
recrystallized by slow vapor diffusion of ether into a dichlo-
romethane solution of the compound. Yield: 0.101 g (88%).
1H NMR (CDCl3): δ 7.83, 7.32 (d, 1H, J ) 7 Hz, C4,7), 7.18
(m, 2H C5,6), 5.24 (2d, 1H each, J ) 7 Hz, cymene), 4.98, 4.48
(d, 1H each, J ) 6 Hz, cymene), 5.06 (br, 1H, NH), 4.18, 3.54,
3.28, 3.10 (m, 1H each, NCH2CH2), 2.90 (sept, 1H, CHMe2),
1.98 (s, 3H, cym-CH3), 1.28, 1.19 (2d, 3H each, J ) 7 Hz, CH-
(CH3)3). 13C NMR (CDCl3): δ 151.76, 132.30, 126.16, 117.86
(quart C’s), 127.61, 125.05, 104.81, 96.65 (indoline arene C’s),
84.18, 82.61, 79.77, 75.52 (cymene C’s), 54.89 (NCH2), 30.59
(NCH2CH2), 29.24 (CHMe2), 22.86 20.91 (CHMe2), 17.87
(cymene-Me). MS (ES): m/z 426 (P+). Anal. Calcd for
Rea ction of 1 w ith Tr ieth yla m in e in th e P r esen ce of
a n Alk en e. To a solution of 1 (0.029 g, 0.036 mmol) in
dichloromethane-d2, 3,3-dimethylbutene (0.0034 g, 0.040 mmol)
and triethylamine (0.0046 g, 0.046 mmol) were added. The
tube was cooled to -196 °C, put under vacuum for 30 min,
and sealed. After the solution was thawed to room tempera-
ture, the reaction was monitored by 1H NMR spectroscopy.
There was an immediate color change from bright yellow to
dark red-orange. Resonances were observed for free indole,
2,2-dimethylbutane, and unidentified ruthenium hydride de-
rivatives with hydride resonances between -5.88 and -10
ppm. After 15 h, 20% of the alkene had converted to the
alkane. After 7 days, ca. 25% of the alkene was converted.
Reactions with excess alkene gave higher alkane yields (see
below). The same reaction was repeated with cycloheptene,
resulting in formation of cycloheptane; however, the results
were not quantified.
C
18H23Cl2NRu: C, 50.83; H, 5.45. Found: C, 50.66; H, 5.73.
Rea ction of 1 w ith Th iop h en ol. Complex 1 (0.104 g,
0.142 mmols) was dissolved in 35 mL of acetonitrile, and
thiophenol (0.0162 g, 0.147 mmols) was then added. After
refluxing for 1 day, the solvent was removed in vacuo and the
orange oil was washed with 2 × 20 mL of diethyl ether. The
orange solid was then recrystallized by layering dichlo-
romethane and diethyl ether overnight to give the known
complex [(cymene)2Ru2(µ-SPh)3](OTf),19 which was identified
1
by H NMR and mass spectroscopy.
Rea ction of 1 w ith Hyd r ogen . Tetrahydrofuran (10 mL)
was added to 1 (0.063 g, 0.086 mmol) in a 25 mL Schlenk tube.
The tube was cooled to -196 °C, charged with 0.79 atm of H2,
and warmed to room temperature. After 23 h of stirring, the
color of the solution changed from yellow to dark orange. The
solution was dried in vacuo. The 1H NMR spectrum (acetone-
d6) of the crude brown oil was very complex with the presence
of four or five cymene-containing products. These were not
identified.
Rea ction of 1 w ith Hyd r ogen a n d Tr ieth yla m in e. The
same reaction as above was repeated with 1 (0.087 g, 0.12
mmol) and triethylamine (0.0116 g, 0.115 mmol). After 19.5
h of stirring, the solvent was removed in vacuo, leaving a dark
brown oil. The 1H NMR spectrum (acetone-d6) showed free
indole and an unidentified ruthenium hydride derivative with
hydride resonances at -13.13 and -14.67 ppm. Attempts to
isolate the pure hydride product by column chromatography
on alumina were unsuccessful.
Rea ction of Cycloh ep ten e w ith a Ca ta lytic Am ou n t of
1. In a NMR Schlenk tube, dichloromethane-d2 was added to
1 (0.410 g, 0.0559 mmol). Under N2 flow, indoline (0.0670 g,
0.562 mmol), cycloheptene (0.0536 g, 0.557 mmol), and tri-
ethylamine (0.0058 g, 0.058 mmol) were added to the Schlenk
tube. The tube was cooled to -196 °C, put under vacuum,
and sealed. The reaction was monitored at room temperature
by 1H NMR spectroscopy. There was an immediate color
change to dark brown with formation of free indole. The
alkane yield after 5 min was approximately 3%, and after 18
h it was 6%. The yield did not increase significantly after the
first day. After 7 days, ca. 7% of the alkene (or 70% based on
Ru complex) had converted to the alkane.
Rea ction of 1 w ith Tr ieth yla m in e. In an NMR Schlenk
tube, triethylamine (0.0044 g, 0.043 mmol) was added to 1
(0.033 g, 0.044 mmol) in dichloromethane-d2 (1 mL). Ni-
tromethane (mL, 0.028 mmol) was added as an internal
standard. The solution was cooled to -196 °C and put under
vacuum for 30 min and the reaction tube was sealed. The
reaction was monitored at room temperature by 1H NMR
spectroscopy. Within 15 min, resonances were observed for
indole, and these resonances continued to increase for about
26 h. Many new resonances were observed in the cymene and
indoline regions, and signals for [(cymene)Ru(η1-indolinyl)(CH3-
CN)x]+ could not be assigned in detail. However, new triplets
observed at δ 3.52 and 4.56 were tentatively assigned to the
indolinyl methylene hydrogens. These signals decreased in
intensity as indole was formed. New ruthenium hydride
resonances were observed at δ -5.83 (s), -7.86 (s), -9.03 (s),
and -13.33 and -14.83 (2 d, J ) 3 Hz). After 1 day, the
hydride resonance at δ -5.83 had disappeared and only those
between δ -7.9 and -15 remained.
Ack n ow led gm en t. Support for this work by the
Division of Chemical Sciences, Office of Basic Energy
Sciences, Office of Energy Research, U.S. Department
of Energy, is gratefully acknowledged. The structure
determinations were performed using equipment ac-
quired under National Science Foundation Grant No.
CHE-9505926. This equipment includes a Siemens P4
diffractometer system and a Silicon Graphics Indigo2
XL workstation.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, structure solution and refinement, atomic coordinates,
bond distances, bond angles, anisotropic displacement param-
eters, and hydrogen coordinates for 1 (16 pages). Ordering
information is given on any current masthead page.
The same reactants were monitored in CD3CN solution. A
spectrum recorded after 20 min indicated that the nitrile
OM970968C
Vasquez, Lisa D.
