Compounds Containing the Cp*Os(NO) Fragment
Organometallics, Vol. 18, No. 11, 1999 2143
and cooled to -20 °C to afford red-orange crystals. Yield: 0.181
g (79%). MS (FD): m/z 451 [M+]. IR (cm-1): 3464 (w), 1738
(s), 1208 (m), 1158 (w), 628 (w), 603 (w), 582 (m), 550 (w), 510
(m).
Exp er im en ta l Section
Gen er a l Deta ils. All experiments were performed under
argon or in a vacuum using standard Schlenk techniques
unless otherwise specified. Solvents were distilled under
nitrogen from magnesium turnings (ethanol), calcium hydride
(dichloromethane), or sodium benzophenone (pentane, ether).
Water was deionized before use. Nitric oxide (Union Carbide,
MG Industries) and zinc dust (Mallinckrodt) were used without
further purification. The dialkylmagnesium reagents were
prepared by modifications of a standard route.30 The starting
material Cp*Os(NO)Br2 was prepared by means of the litera-
ture method19 and washed with pentane to remove trace
Cp*2Os impurities.
The IR spectra were obtained on a Nicolet Impact 410 as
Nujol mulls between KBr plates. The 1H and 13C NMR data
were recorded on Varian Unity-400 spectrometers at 400 and
125 MHz, respectively. Chemical shifts are reported in parts
per million (δ) downfield from tetramethylsilane. Field-de-
sorption (FD) mass spectra were performed on a Finnigan-
MAT 731 mass spectrometer; the samples were loaded as
CH2Cl2 solutions, and the spectrometer source temperature
was 100 °C. Positive-ion fast-atom bombardment (FAB) mass
spectra were performed on a VG ZAB-SE mass spectrometer
as CH2Cl2 solutions. The shapes of all peak envelopes cor-
respond with those calculated from the natural abundance
isotopic distributions. Cyclic voltammograms were obtained
on a BAS CV 50W Voltammetric Analyzer; the supporting
electrolyte was [N(n-Bu)4]PF6, and the working electrode was
constructed of platinum. Melting points were measured on a
Thomas-Hoover Unimelt apparatus in sealed capillaries under
argon. Microanalyses were performed by the staff of the
Microanalytical Laboratory of the School of Chemical Sciences
at the University of Illinois.
(P en t a m et h ylcyclop en t a d ien yl)n it r osyld ih yd r id oos-
m iu m (II), Cp *Os(NO)H2 (2). To a mixture of Cp*Os(NO)Br2
(0.30 g, 0.59 mmol) and NaBH4 (0.80 g, 2.1 mmol) was added
ethanol (30 mL). Upon addition of the solvent, gas was evolved
(H2), and the solution color became brown. The solution was
stirred for 1 h, and then the solvent was removed under
vacuum. The resulting residue was extracted with pentane (3
× 15 mL), and the brown extracts were filtered. The pentane
was removed under vacuum, and the resulting solid was
sublimed at 10-3 Torr over 4 h at 50 °C to afford a yellow solid.
Yield: 0.085 g (40%). MS (FD): m/z 359 [M+]. IR (cm-1): 3375
(w), 2096 (s), 1735 (s), 1070 (m), 1042 (m), 856 (w), 789 (s),
749 (m), 620 (m), 535 (m).
Bis(pen tam eth ylcyclopen tadien yl)din itr osyldiosm iu m -
(0), [Cp *Os(µ-NO)]2 (3). To a suspension of Cp*Os(NO)Br2
(0.325 g, 0.63 mmol) in ethanol (50 mL) was added zinc dust
(0.14 g, 2.1 mmol). The mixture was heated to reflux for 3 h,
during which time the purple solution became red. The solvent
was removed under vacuum, and the residue was dissolved
in tetrahydrofuran (20 mL). The solution was filtered through
Celite in air and then concentrated to 5 mL. The red micro-
crystalline precipitate was collected by filtration and dried
under vacuum. Yield: 0.171 g (76%). MS (FD): m/z 712 [M+].
IR (cm-1): 1408 (s), 1340 (s), 1159 (w), 1069 (m), 702 (s), 610
(w), 581 (m), 440 (w).
(P en t a m et h ylcyclop en t a d ien yl)n it r osyl[(t r im et h yl-
silyl)m eth yl]br om oosm iu m (II), Cp *Os(NO)(CH2SiMe3)-
Br (5). The procedure for the synthesis of Cp*Os(NO)MeBr
was followed; the reagents used were Cp*Os(NO)Br2 (0.11 g,
0.20 mmol) and Mg(CH2SiMe3)2 (3 mL of a 0.4 M solution in
diethyl ether, 1.20 mmol). Yield: 0.081 g (74%). MS (FD): m/z
523 [M+]. IR (cm-1): 3414 (w), 1724 (s), 1230 (m), 1239 (m),
1025 (m), 864 (m), 835 (m), 732 (w), 679 (w), 563 (w).
(P en t a m et h ylcyclop en t a d ien yl)n it r osyl(p h en yl)b r o-
m oosm iu m (II), Cp *Os(NO)P h Br (6). To a suspension of
Cp*Os(NO)Br2 (0.11 g, 0.20 mmol) in diethyl ether (30 mL)
was added diphenylmagnesium (2 mL of a 0.5 M solution in
diethyl ether, 1.0 mmol). The purple mixture was stirred for
4 h, during which time the suspension dissolved and the
solution color became dark red. The solution was taken to
dryness in a vacuum, and the resulting residue was extracted
with dichloromethane (30 mL). The extract was washed in air
with water (3 × 20 mL), dried over magnesium sulfate, and
filtered. The dichloromethane was removed under vacuum, and
the resulting dark red solid was dissolved in tetrahydrofuran
(5 mL). The solution was concentrated to ∼1 mL, layered with
pentane (10 mL), and cooled to -20 °C to afford maroon
crystals. Yield: 0.067 g (64%). MS (FAB): m/z 513 [M+]. IR
(cm-1): 3054 (w), 1740 (s), 1566 (m), 1070 (w), 1042 (w), 1020
(m), 750 (s), 708 (m), 508 (w).
(P en t a m et h ylcyclop en t a d ien yl)n it r osyl(o-t olyl)b r o-
m oosm iu m (II), Cp *Os(NO)(o-Tol)Br (7). To a suspension
of Cp*Os(NO)Br2 (0.10 g, 0.20 mmol) in diethyl ether (30 mL)
was added di(o-tolyl)magnesium (2.45 mL of a 0.20 M solution
in diethyl ether, 0.49 mmol). The purple mixture was stirred
for 18 h, during which time the suspension dissolved and the
solution color became dark red. The solution was taken to
dryness in a vacuum, and the resulting residue was extracted
with dichloromethane (30 mL). The extract was washed in air
with water (3 × 20 mL), dried over magnesium sulfate, and
filtered. The dichloromethane was removed under vacuum, and
the resulting dark red solid was dissolved in tetrahydrofuran
(5 mL). The solution was concentrated to ∼1 mL, layered with
pentane (10 mL), and cooled to -20 °C to afford maroon
crystals. Yield: 0.087 g (81%). MS (FAB): m/z 527[M+]. IR
(cm-1): 1729 (s), 1575 (m), 1161 (w), 1031 (s), 754 (w).
(P e n t a m e t h ylc yc lop e n t a d ie n yl)n it r osyld im e t h yl-
osm iu m (II), Cp *Os(NO)Me2 (8). To a solution of Cp*Os(NO)-
MeBr (0.02 g, 0.04 mmol) in dichloromethane (30 mL) was
added silver triflate (0.02 g, 0.08 mmol). The solution was
stirred for 2.5 h, and a white precipitate formed after 20 min.
The yellow solution was filtered, and the filtrate was taken to
dryness under vacuum. The resulting yellow solid was dis-
solved in diethyl either (30 mL) and treated with dimethyl-
magnesium (0.5 mL of a 1.4 M solution in diethyl ether, 0.69
mmol). The solution was stirred for 5 h, and then the solvent
was removed under vacuum. The residue was extracted with
pentane, and the filtrate was taken to dryness under vacuum
to yield a yellow solid. MS (FD): 385 m/z [M+]. IR (cm-1): 1696
(νNO).
Cr yst a llogr a p h ic St u d y. Single crystals of [Cp*Os-
(µ-NO)]2, grown from acetonitrile, were mounted on glass fibers
with Paratone-N oil (Exxon) and immediately cooled to -75
°C in a cold nitrogen gas stream on the diffractometer.
Standard peak search and indexing procedures,31 followed by
least-squares refinement31 using 3425 reflections, yielded the
cell dimensions given in Table 3.
Data were collected with an area detector by using the
measurement parameters listed in Table 3. Systematic ab-
sences for 0k0 (k * 2n) and h0l (h + l * 2n) were only
consistent with space group P21/n. The measured intensities
were reduced to structure factor amplitudes and their esd’s
(P en t a m et h ylcyclop en t a d ien yl)n it r osyl(m et h yl)b r o-
m oosm iu m (II), Cp *Os(NO)MeBr (4). To a suspension of
Cp*Os(NO)Br2 (0.30 g, 0.60 mmol) in diethyl ether (35 mL)
was added dimethylmagnesium (2.0 mL of a 1.4 M solution in
diethyl ether, 2.8 mmol). The purple mixture was stirred for
5 h, during which time the suspension dissolved and the
solution color became dark reddish-brown. The solution was
washed in air with water (3 × 20 mL), dried over magnesium
sulfate, and filtered. The solution was concentrated to 3 mL
(30) Andersen, R. A.; Wilkinson, G. Inorg. Synth. 1979, 19, 262-
265.
Brumaghim, Julia L.
