Reactivity of the imido group in [CpOs(NCH3)(CH2SiMe3)2][SO 3CF3]

Article abstract of DOI:10.1021/om950644t

The imido ligand in [(η⁵-C₅H₅)Os(NCH₃)(CH ₂SiMe₃)₂][SO₃CF₃] reacts with basic and nucleophilic molecules. Triphenylphosphine, pyridine, and water act as bas

Full text of DOI:10.1021/om950644t

1622
Organometallics 1996, 15, 1622-1629
Rea ctivity of th e Im id o Gr ou p in
[Cp Os(NCH3)(CH2SiMe3)2][SO3CF 3]
Patricia A. Shapley,* J eanine M. Shusta, and J ennifer L. Hunt
Department of Chemistry, University of Illinois, Urbana, Illinois 61801
Received August 15, 1995X
The imido ligand in [(η5-C5H5)Os(NCH3)(CH2SiMe3)2][SO3CF3] reacts with basic and
nucleophilic molecules. Triphenylphosphine, pyridine, and water act as bases and depro-
tonate the methylimido ligand forming the first osmium(IV) methyleneamido complex, (η5-
C5H5)Os(NdCH2)(CH2SiMe3)2. The reaction is reversible, and treatment of (η5-C5H5)-
Os(NdCH2)(CH2SiMe3)2 with HBF4 produces [(η5-C5H5)Os(NCH3)(CH2SiMe3)2][BF4]. Tri-
phenylphosphine also abstracts the imido ligand to form MeNdPPh3. The imido complex
reacts with ethylene to produce an olefin complex, [(η5-C5H5)Os(NHCH2)(CH2CH2)2][SO3-
CF3]. Under pressures of ethylene, products resulting from imide transfer to the olefin are
obtained.
14
In tr od u ction
plexes OsOx(NR)4-x
,
a homoleptic imido complex Os-
(NR)3 and derivatives of this complex,15 a porphyrin
complex,16 and a low-valent arene complex.17
Transition metal imido complexes are important
species in inorganic chemistry.1 They have been pro-
posed as intermediates in certain nitrogen fixation2 and
industrial ammoxidation3 processes. One of the major
focuses in the study of metal imido complexes today is
to demonstrate their ability to transfer the nitrogen
moiety to unsaturated substrates.
We have synthesized (η5-C5R5)Os(N)(CH2SiMe3)2 (R
) H, Me) by the reactions of [NBu4][Os(N)(CH2SiMe3)2-
Cl2] or [Os(N)(CH2SiMe3)2Cl]2 and NaC5H5 or LiC5-
Me5.18 The methyl complexes, (η5-C5R5)Os(N)(CH3)2 (R
) H, Me), were prepared similarly.19 The osmium
centers in these coordinatively saturated nitrido com-
plexes are relatively unreactive, but the nitrido ligands
act as a weak Lewis base, coordinating reversibly to the
Lewis acids Ag+ and BF3. The nitrido ligand is alky-
lated by organic electrophiles. The reaction of (η5-
C5H5)Os(N)(CH2SiMe3)2 with methyl trifluoromethane-
sulfonate results in the formation of a cationic methyl-
imido complex, [(η5-C5H5)Os(NCH3)(CH2SiMe3)2][SO3-
CF3], 1 (Scheme 1).
Transition metal alkylimido complexes containing a
variety of ancillary ligands, including some organome-
tallic alkylimido complexes, are known.4-7 Complexes
containing a cyclopentadienyl ligand are known for
zirconium, vanadium, niobium tantalum, rhenium, and
iridium.8-11 We previously reported the synthesis and
characterization of (alkylimido)osmium alkyl complexes,
Os(NR′)R4,12 and have also prepared the analogous
ruthenium species.13 Other known osmium alkylimido
and arylimido complexes include the oxo-imido com-
(8) (a) Cummins, C. C.; Baxter, S. M.; Wolczanski, P. T. J . Am.Chem.
Soc. 1988, 110, 8731-8733. (b) Preuss, F.; Becker, H.; Wieland, T. Z.
Naturforsch 1990, 45b, 191-18. (c) Buijink, J . F.; Teuben, J . K.;
Kooijman, H.; Spek, A. L. Organometallics 1994, 13, 2922-2924. (d)
Poole, A. D.; Williams, D. N.; Kenwright, A. M.; Gibson, V. C.; Clegg,
W.; Hockless, D. C. R.; O’Neil, P. A. Organometallics 1993, 12, 2549-
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Soc., Dalton Trans. 1993, 3031-3034. (f) Gibson, V. C.; Poole, A. D.;
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Organomet. Chem. 1993, 462, C12-C14. (g) Baldwin, T. C.; Huber, S.
R.; Bruck, M. A.; Wigley, D. E. Inorg. Chem. 1993, 32, 5682-5686. (h)
Glueck, D. S.; Hollander, F. J .; Bergmann, R. G. J . Am. Chem. Soc.
1989, 111, 2719-2721.
X Abstract published in Advance ACS Abstracts, February 1, 1996.
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B. L. Coord. Chem. Rev. 1980, 31, 123-175.
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Radiochem. 1983, 27, 197. (b) Chatt, J .; Dilworth, J . R.; Richards, R.
L. Chem. Rev. 1977, 78, 589-625. (c) Thorneley, R. N. F.; Lowe, D. J .
In Metals in Biology; Spiro, T., Ed.; Wiley: New York, 1984; Chapter
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W. J . Proc. Natl. Acad. Sci. U.S.A. 1977, 74, 3249. (f) Molybdenum
and Molybdenum-Containing Enzymes; Coughlin, M., Ed.; Pergamon:
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F., Bottomley, F., Eds.; Wiley-Interscience: New York, 1979.
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Commun. 1993, 1125-1127. (b) Belgacem, J .; Kress, J .; Osborn, J . A.
J . Mol. Catal. 1994, 86, 267-85.
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9, 489-496.
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1993, 12, 3705-3723.
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mann, G.; Schupp, O. J . Organomet. Chem. 1993, 444, C37-C40. (b)
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Chem. Soc., Chem. Comm. 1986, 1398-1399. (c) Takacs, J .; Herrmann,
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C.; Ros, C.; Feneau-Dupont, J .; Declercq, J . P. Polyhedron 1993, 12,
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(19) Shusta, J . Ph.D Thesis, University of Illinois, 1992.
0276-7333/96/2315-1622$12.00/0 © 1996 American Chemical Society

[CpOs(NCH3)(CH2SiMe3)2][SO3CF3]
Organometallics, Vol. 15, No. 6, 1996 1623
Sch em e 1
Sch em e 3
Sch em e 2
Complex 2 was characterized by elemental analysis
and spectroscopic methods. It is a diamagnetic osmium-
(IV) complex. The 1H NMR spectrum of 2 includes
resonances for the cyclopentadienyl protons and meth-
ylene and methyl protons of the (trimethylsily)methyl
ligands and a singlet for the protons of the methylene-
amido ligand at -0.56 ppm. In the labeled complex, (η5-
C5H5)Os(15NdCH2)(CH2SiMe3)2, the resonance at -0.56
ppm is split into a doublet with a coupling constant of
3.1 Hz by the 15N nucleus. The proton-decoupled 13C
NMR spectrum of 2 shows a singlet at δ 128.95 for the
carbon of the methyleneamido group along with reso-
nances for the carbons of the equivalent alkyl ligands
and the carbons of the cyclopentadienyl group. The
infrared spectrum of 2 includes a band at 1606 cm-1
for the NdCH2 stretch.
The methyleneamido ligand is reprotonated at carbon
by strong acids. Tetrafluoroboric acid converts 2 to the
tetrafluoroborate salt of 1. Neither pyridinium tet-
rafluoroborate nor triphenylphosphonium tetrafluorobo-
rate reacted rapidly with 2. After several days, both
[Hpy][BF4] and [HPPh3][BF4] caused some decomposi-
tion of 2, producing SiMe4 by protonolysis of the alkyl
ligands. Complex 2 does not react with ethylene or with
PPh3.
Rea ction of 1 w ith P P h 3. Triphenylphosphine
reacts with 1 as both a base and as a nucleophile. The
reaction of 1 with 2 equiv of triphenylphosphine gives
nearly equal amounts of 2 and [(η5-C5H5)Os(CH2-
SiMe3)2(PPh3)][SO3CF3], 3, by 1H NMR, along with
[HPPh3][SO3CF3] and MeNdPPh3 (Scheme 3). An
intermediate species, which we presume to be [(η5-
C5H5)Os(CH2SiMe3)2(MeNdPPh3)][SO3CF3], can be ob-
served in solution but has not been isolated. In the 31P
NMR spectrum, the signals for the intermediate (19.3
ppm) and for PPh3 (-4.9 ppm) decrease as the signals
for free MeNdPPh3 (15.7 ppm) and 3 (53.7 ppm)
increase. When [(η5-C5H5)Os(15NCH3)(CH2SiMe3)2][SO3-
CF3] is treated with PPh3, the labeled nitrogen is found
in Me15NdPPh3. We also observe [(η5-C5H5)Os(CH2-
SiMe3)2(Me15NdPPh3)][SO3CF3] in solution. The reso-
nances associated with these compounds in the proton-
decoupled 31P NMR spectrum are split into doublets due
to 31P-15N coupling.
The methylimido ligand in 1 is quite reactive, and it
can be transferred to certain unsaturated organic
molecules. In this paper we report some of the reaction
chemistry of this complex with nucleophiles.
Resu lts
Complex 1 can be obtained in only moderate yields
by the alkylation of (η5-C5H5)Os(N)(CH2SiMe3)2 with
CH3SO3CF3 because the alkylation reaction is slow at
room temperature and the product is thermally un-
stable. It decomposes slowly in solution to produce an
insoluble solid and organic products derived from the
alkyl ligands: Me3SiCH2CH2SiMe3 and SiMe4. Com-
plex 1 does not react with carbon monoxide at 500 psi,
25 °C, but does react with other Lewis bases.
Depr oton ation of [(η5-C5H5)Os(NMe)(CH2SiMe3)2]-
[SO3CF 3]. The methylimido complex, 1, is acidic. The
addition of 1 equiv of NaH to a THF solution of 1 results
in an immediate reaction. The color changes from
orange to purple and hydrogen gas bubbles from the
solution. After purification of the crude product by
column chromatography or by crystallization from hex-
ane, we obtain (η5-C5H5)Os(NdCH2)(CH2SiMe3)2, 2, in
94% yield (Scheme 2). Complex 1 also reacts with
pyridine to give 2. Even water is able to slowly
deprotonate the methylimido group in 1. The 15N-
labeled complex (η5-C5H5)Os(15NdCH2)(CH2SiMe3)2 re-
sults from the deprotonation of [(η5-C5H5)Os(15NMe)-
(CH2SiMe3)2][SO3CF3].
Complex 2 can be isolated in 49% yield from the
reaction mixture. Complex 3 is more sensitive than is

1624 Organometallics, Vol. 15, No. 6, 1996
Shapley et al.
to N-H (J ) 12.9, 12.9 Hz). In 15N-labeled 4, the N-H
Sch em e 4
resonance is coupled to the adjacent 15N atom (J NH
)
76.0 Hz) and to the nonequivalent methylene protons
of the methyleneimino ligand (J ) 20.2, 12.9 Hz).
Symmetric multiplets at δ 3.18 and 3.02 having an
AA′BB′ second-order splitting pattern are assigned to
the protons of the η2-bonded olefin, and the singlet at δ
5.39 is assigned to the equivalent cyclopentadienyl
protons. The AA′BB′ pattern was simulated using the
ITRCAL program in order to obtain the accurate
coupling constants and chemical shift data for the
nonequivalent olefin protons.
The protons of the cyclopentadienyl ligand, the meth-
yleneimino ligand, and the ethylene ligands relax at
quite different rates (T1). An optimal delay time of 25
s gave accurate integrations for each multiplet in the
1H NMR spectrum of 4. The COSY spectrum obtained
of 4 showed correlations among the resonances at δ 7.95,
7.59, and 12.15, and between the resonances at δ 3.18
and 3.02. Three resonances are observed in the 13C
NMR spectrum of 4 for the methylene carbon of imine
ligand, for the equivalent carbons of the two ethylene
ligands, and for the equivalent cyclopentadienyl car-
bons. The HETCOR and APT spectra verified the
heteronuclear correlations and carbon types.
The IR spectrum of 4 includes a NH stretching
absorption at 3155 cm-1 and bands for the aromatic and
olefinic C-H stretching vibrations. An intense absorp-
tion at 1382 cm-1 may be assigned to a C-N stretching
vibration.
1H NMR spectroscopy shows that 4 slowly converts
to an isomeric complex, 4′. The multiplets due to the
methyleneimino ligand and the two olefin ligands shift
downfield slightly, while the coupling constants and
splitting patterns remain the same.
Complex 1 reacts with ethylene at higher pressure
to give products in which the methylimido group was
transferred to the olefin. After a solution of 1 was
stirred at 760 psi, 41 °C, for 4 days, volatile organic
products derived from the (trimethylsilyl)methyl ligands
and ethylene, a nonvolatile polymeric mixture derived
from N-methylaziridine, and an insoluble osmium-
containing material were produced. When 15N-labeled
1 was treated with ethylene under these conditions,
essentially all of the 15N label was in the nonvolatile
fraction. The volatile organic products were distilled
and analyzed by GCMS. This mixture contained pro-
penyl(trimethyl)silane, tetramethysilane, butene, and
small amounts of hexamethyldisiloxane and octameth-
yltrisiloxane. No N-methylaziridine was detected in the
volatile organic products.
2, and it reacts with [HPPh3]+ formed in the reaction
to give Me4Si and insoluble osmium-containing prod-
ucts. It also reacts with additional PPh3. The isolated
yields of 3 are low. The organic products from this
1
reaction were identified by comparison of their H, 13C,
and 31P NMR spectra with those of authentic samples.
The 1H NMR spectrum of 3 shows a singlet at δ -0.16
for the methyl protons of the (trimethylsilyl)methyl
ligands, a singlet at δ 4.94 for the equivalent cyclopen-
tadienyl protons and multiplets in the aromatic region
for the phenyl protons. The methylene protons of the
alkyl ligands appear as a pair of doublet of doublets at
δ 3.85 and 1.95 due to both H-H and P-H coupling.
The 13C NMR spectrum gives a doublet at δ 83.21 with
J PC ) 2.2 Hz assigned to the cyclopentadienyl carbons,
a doublet at δ 3.09 with a J PC ) 3.1 Hz assigned to the
methylene carbons of the (trimethylsilyl)methyl ligands,
and a singlet at δ 0.02 for the methyl carbons of the
(trimethylsilyl)methyl ligands.
Rea ction of 1 w ith Eth ylen e. The methylimido
complex reacts with ethylene to give a single product.
The reaction of 1 in methylene chloride solution with
an excess of ethylene at approximately 1 atm, 25 °C,
produces a π-bonded imine complex [(η5-C5H5)Os(η2-
HNdCH2)(η2-C2H4)2][SO3CF3], 4 (Scheme 4). The or-
ganic products of the reaction are derived from the
(trimethylsilyl)methyl ligands and include Me3SiCH2-
CH2SiMe3, SiMe4, and small quantities of Me3SiOH and
Me3SiOSiMe3. The trimethylsilanol and hexamethyl-
disiloxane probably result from trace quantities of water
in the ethylene. The 15N-labeled complex, [(η5-C5H5)-
Os(η2-H15NdCH2)(η2-CH2dCH2)2][SO3CF3], is prepared
from [(η5-C5H5)Os(15NCH3)(CH2SiMe3)2][SO3CF3] and
ethylene. Analytically pure crystals of 4 are obtained
by rapid crystallization in THF/hexane solutions at -30
°C. Complex 4 is unstable in coordinating solvents and
decomposes slowly in THF or acetonitrile solution with
loss of ethylene. Trace amounts of 4 are also formed in
the hydrolysis of 1 in the absence of ethylene.
A pure sample of N-methylaziridine was exposed to
1
the reaction conditions above. The H NMR spectrum,
UV-visible spectrum, and mass spectrum of the poly-
meric product mixture from N-methylaziridine/ethylene
were identical to that of the soluble, non-volatile fraction
from 1/ethylene.
1
The H NMR spectrum of 4 shows resonances for the
imine and ethylene ligands. The nonequivalent meth-
ylene protons of the methyleneimino ligand are found
at δ 7.59 and at δ 7.95, and a broad singlet at δ 12.15
is assigned to the proton on the quadripolar 14N nucleus.
The multiplet at δ 7.59 is assigned to the methylene
proton trans to N-H (J ) 20.2, 12.9 Hz) while the
multiplet at δ 7.95 is due to the methylene proton cis
Discu ssion
Com p a r ison of th e Rea ctivity of 1 w ith Th a t of
Os(NCH3)(CH2SiMe3)4. A series of osmium(VI) alkyl-
imido complexes Os(NR)R′4 (R ) CH3, CH2CH3, SiMe3,
CH2CHdCH2; R′ ) CH3, CH2Ph, CH2SiMe3, CH2-
CHdCH2) were prepared previously in this labora-

[CpOs(NCH3)(CH2SiMe3)2][SO3CF3]
Organometallics, Vol. 15, No. 6, 1996 1625
Sch em e 5
tory.12,20 The reaction chemistry of Os(NCH3)(CH2-
SiMe3)4, 5, has been thoroughly studied and can be
compared with that of 1.21 The reaction chemistry of
the two methylimido complexes is very different (Scheme
5). Unlike 1, 5 is not deprotonated by pyridine or
phosphines. We seen no evidence for the formation of
methyleneamido complexes in the reactions of 5 with
bases. The methylimido group in 5 is not transferred
to either phosphines or to olefins. We have seen no
reaction between 5 and PPh3, the more basic PMe3, or
C2H4. Carbon monoxide does react with 5 in a stepwise
fashion. Strong acids protonate the alkyl ligands in
both 1 and 5, leading to decomposition of the complexes.
results in the conversion of the imido to an imine ligand.
Reactions with PPh3 or ethylene (high pressure) result
in the complete loss of the imido group.
Acid ity of th e Meth ylim id o Gr ou p in 1. Complex
1 is a surprisingly strong carbon acid, deprotonated by
even weak bases. Enhanced acidity has been observed
for the â-hydrogen atoms of alkylimido groups in some
other transition metal imido complexes, and this acidity
may be explained by the electron-accepting character
of the imido nitrogen atom. Chatt has demonstrated
that the rhenium complexes Re(NCH2R)Cl2L2 (R ) H,
CH3, CH2CH3; L ) PPh3, PMePh2, PEtPh2) are depro-
tonated with pyridine to give the (alkylideneamido)-
rhenium(III) complexes Re(NdCHR)Cl2L2(NC5H5).24 The
tungsten hydridotris(3,5-dimethylpyrazolyl)borate com-
plexes [Tp′(CO)2W(NCH2R)][PF6] (R ) Pr, Ph) are also
deprotonated by NEt3 to form Tp′(CO)2W(NdCHR).25
The greatly enhanced reactivity of the methylimido
group in 1 over 5 can be explained as a result of π
competition. Complex 5 has only a single π-donor
ligand. The nitrogen p orbitals can form two strong
π-bonds with the dxz and dyz orbitals on the metal. The
η5-cyclopentadienyl ligand and the methylimido ligand
in 1 each require one σ symmetry metal orbital and two
π symmetry orbitals on osmium for bonding, and the
ligands are competing with each other for the metal
π-symmetry orbitals. This can lead to structural distor-
tions or increased reactivity of the π-bonded ligands.22
There is a distinct ring slippage of the cyclopentadienyl
ligand in the silver(I) adduct {(η5-C5H5)Os(CH2SiMe3)-
(N)}2AgBF4.18 A similar distortion has been observed
previously in certain cyclopentadienyl complexes with
oxo, imido, and µ-dinitrogen ligands.9,23 Reactions lead-
ing to loss of the methylimido ligand or a modification
of the ligand to reduce π-bonding should be favorable
for 1. These are observed. Deprotonation converts the
triply-bonded imido to a doubly-bonded amido ligand.
The reaction with ethylene under mild conditions
The methyleneamido ligand in 2 is probably bonded
linearly to the osmium center, forming a double bond.
The methylene protons are equivalent at room temper-
1
ature and remain equivalent in the low temperature H
NMR spectra. There is a moderately strong C-N
double bond as shown by the C-N stretching vibration
at 1606 cm-1 in the IR spectrum. The NdC stretching
vibrations of the reported alkylideneamido complexes
occur in the range 1325-1725 cm-1 25,26
Many inorganic
.
osmium(IV) complexes are paramagnetic, but 2, with
its high-field ligands, is a diamagnetic species.
Tr a n sfer of th e Meth ylim id o Gr ou p in 1 to P P h 3.
Certain transition metal imido complexes have an
electrophilic character and react with phosphines at the
imido nitrogen. McElwee-White has shown that (CO)5-
WdNPh reacts with PPh3 to form (CO)5W(PhNPPh3)
and, upon addition of carbon monoxide to the metal,
(20) Zhang, N. Ph.D. Thesis, University of Illinois, 1991.
(21) Marshman, R. W.; Shapley, P. A. J . Am. Chem. Soc. 1990, 112,
8369-8378.
(24) Chatt, J .; Dosser, R. J .; King, F.; Leigh, G. J . J . Chem. Soc.,
Dalton Trans. 1976, 2435-2443.
(22) Rappe, A. K.; Goddard, W. A. J . Am. Chem. Soc. 1982, 104,
3287-3294.
(25) Powell, K. R.; Pe´rez, P. J .; Luan, L.; Feng, S. G.; White, P. S.;
Brookhart, M.; Templeton, J . L. Organometallics 1994, 13, 1851-1864.
(26) (a) Farmery, K.; Kilner, M.; Midcalf, C. J . Chem. Soc. A 1970,
2279-2285. (b) Bercaw, J . E.; Davies, D. L.; Wolczanski, P. T.
Organometallics 1986, 5, 443-450. (c) Erker, G.; Fromberg, W.;
Atwood, J . L.; Hunter, W. E. Angew. Chem., Int. Ed. Engl. 1984, 23,
68-69.
(23) (a) O’Regan, M. B.; Liu, A. H.; Finch, W. C.; Schrock, R. R.;
Davis, W. M. J . Am. Chem. Soc. 1990, 112, 4331-4338. (b) Churchill,
M. R.; Li, Y. J . J . Organomet. Chem. 1986, 301, 49-59. (c) Herrmann,
W. A.; Felixberger, J . K.; Anwander, R.; Herdtweck, E.; Kiprof, P.;
Riede, J . Organometallics 1990, 9, 1434-1443.

1626 Organometallics, Vol. 15, No. 6, 1996
Shapley et al.
Sch em e 6
F igu r e 1. Proposed structure of 4.
Sch em e 7
PhNdPPh3.27 A hydrazido tungsten complex behaves
similarly.28 Other imido complexes have been shown
to react with trialkyl- or triarylphosphines to form the
free phosphinimines and the reduced metal com-
plexes.15,29
The methyleneamido complex 2 cannot be an inter-
mediate in the formation of 3 and Ph3PdNMe because
2 does not react with PPh3 or with [HPPh3]+. Nucleo-
philic attack of PPh3 on the imido nitrogen of 1 forms a
phosphinimine complex, (η5-C5H5)Os(MeNPPh3)(CH2-
SiMe3)2. The phosphinimine complex is unstable and
loses MeNdPPh3 in the presence of excess phosphine
to give 3.
synthesis of the methyleneimino complex (η5-C5Me5)-
Ta(MeNdCH2)Me2 was reported by Bercaw.11 The C-N
stretching vibration in the IR spectrum of 4 shows that
the imine ligand has more single-bond than double-bond
character. This has been observed in other reported
imine complexes. The osmium-imine ligand is best
represented as a heterometallacyclopropane. The ki-
netic product of the reaction may be the sterically
favorable isomer with the methylene trans to the
cyclopentadiene ligand. Later transition metals usually
form stronger bonds with carbon atoms than with
nitrogen or oxygen atoms. The sterically favored kinetic
product should isomerize because having the methylene
ligand trans to the cyclopentadienyl ligand should be
thermodynamically less favorable than having the
nitrogen ligand in this position (Scheme 7).
Syn th esis a n d Str u ctu r e of 4. Data from the NMR
spectra of 4 allow us to propose a structure for this
molecule. The carbon atoms of the two coordinated
ethylene ligands are equivalent in the 13C NMR spec-
trum. 1H NMR shows two sets of ethylene protons in a
AA′BB′ spin system. This has been observed in other
ethylene complexes.30 For example, the iridium(I) eth-
ylene complexes (η5-C5H5)Ir(CH2dCH2)L and (η5-C9H7)-
Ir(CH2dCH2)L, where L ) C2H4, CO, show an AA′BB′
1
spin system in the H NMR spectrum for the ethylene
ligand with coupling constants and chemical shifts
similar to those of 4.31 To explain the equivalence of
the carbon atoms, the ethylene ligands must be freely
rotating about the osmium-ethylene axis. If the imino
ligand lies in the plane which bisects the olefin ligands,
rotation of each ethylene ligand would cause HA to
rotate into the position of HA′ and HB into HB′ (Figure
1). Even in this symmetrical structure, the nitrogen-
bound hydrogen would be pointed toward one of the two
coordinated olefins making them inequivalent. Note
that the methylene protons of the imine are inequivalent
and show separate cis and trans coupling constants to
this proton. However, the chemical shift differences of
the resonances in these inequivalent ethylene ligands
is much smaller than we can detect even in the 1H NMR
spectrum obtained on a 500 MHz instrument.
Reductive elimination of the alkyl ligands precedes
isomerization of the methylimido ligand in the formation
of 4 from 1. Complex 2 is protonated at carbon, not at
nitrogen, by strong acids, and 2 does not react with
ethylene. Reductive elimination of the alkyl ligands
from 1 occurs slowly in solution, even in the absence of
ethylene. Ethylene accelerates this process and allows
us to trap the reduced metal complex. The strong
π-donor imido ligand in the d4 complex [CpL2Os≡
NCH3][SO3CF3] would be destabilized and should rap-
idly isomerize (Scheme 8).
Complex 4 is also produced in small quantities by the
reaction of 1 with degassed water. The tetramethylsi-
lane is produced by protonation of one of the (trimeth-
ylsilyl)methyl ligands, while the hexamethyldisiloxane
is formed by the hydrolysis of a Si-C bond in this
ligand. Hydrolysis of the (trimethylsilyl)methyl ligand
may also produce a transient methylene species that
Complexes containing coordinated simple monoden-
tate imines have been isolated.32 For example, the
(27) Sleiman, H. F.; Mercer, S.; McElwee-White, L. J . Am. Chem.
Soc. 1989, 111, 8007-8009.
(28) Arntdsen, B. A.; Sleiman, H. F.; McElwee-White, L. Organo-
metallics 1993, 12, 2440-2444.
(29) (a) Dobbs, D. A.; Bergman, R. G. J . Am. Chem. Soc. 1993, 115,
3836-3837. (b) Huang, J .-S.; Che, C.-M.; Poon, C.-K. J . Chem. Soc.,
Chem. Commun. 1992, 161-163. (c) Fourquet, J . L; Leblanc, M.;
Saravanamuthu, A.; Bruce, M. R. M.; Bruce, A. E. Inorg. Chem. 1991,
30 , 3241-3243. (d) Harlan, E. W.; Holm, T. H. J . Am. Chem. Soc.
1990, 112, 186-193. (e) Elliot, R. L.; Nichols, P. J .; West, B. O.
Polyhedron 1987, 6, 2191-2192. (f) Moubaraki, B.; Murray, K. S.;
Nichols, P. J .; Thomson, S.; West, B. O. Polyhedron 1994, 13, 485-
495.
(32) (a) Adams, R. D.; Chen, G. Organometallics 1992, 11, 3510-
3511. (b) Diamond, S. E.; Tom, G. M.; Taube, H. J . Am. Chem. Soc.
1975, 97, 2661-2664. (c) Adcock, P. A.; Keene, F. R. J . Am. Chem.
Soc. 1981, 103, 6494-6495. (d) Lay, P. A.; Sargeson, A. M.; Skelton,
B. W.; White, A. H. J . Am. Chem. Soc. 1982, 104, 6161-6164 and
references therein. (e) Adcock, P. A.; Keene, F. R.; Smythe, R. S.; Snow,
M. R. Inorg. Chem. 1984, 23, 2336-2343. (f) Lay, P. A.; Sargeson, A.
M.; Skelton, B. W.; White, A. H. J . Am. Chem. Soc. 1982, 104, 6161-
6164 (g) Chiu, K. W.; J ones, R. A.; Wilkinson, G.; Galas, A. M. R.;
Hursthouse, M. B. J . Am. Chem. Soc. 1980, 102, 7979-7980. (h) Chiu
K. W.; J ones, R. A.; Wilkinson, G.; Galas, A. M. R.; Hursthouse, M. B.
J . Chem. Soc., Dalton Trans. 1981, 2088-2097. (i) Takahashi, Yl.;
Onoyama, N.; Ishikawa, Y.; Motojima, S.; Sugiyama, K. Chem. Lett.
1978, 525-528.
(30) Eppley, D. F.; Wolczanski, P. T.; Van Duyne, D. Angew. Chem.,
Int. Ed. Engl. 1991, 5, 584-585.
(31) Szajek, L. P.; Lawson, R. J .; Shapley, J . R. Organometallics
1991, 10, 357-361.

[CpOs(NCH3)(CH2SiMe3)2][SO3CF3]
Organometallics, Vol. 15, No. 6, 1996 1627
Sch em e 8
Con clu sion
The nitrido complexes (η5-C5H5)Os(N)(CH2SiMe3)2
and [N(n-Bu)4][Os(N)(CH2SiMe3)4] are methylated by
methyl trifluoromethanesulfonate giving the correspond-
ing imido species, 1 and 5, respectively. The reactivity
of 1 is much greater than 5. The increased reactivity
may be attributed to the presence of two π-donor ligands
in the former complex. Complex 1 is thermally un-
stable, and the alkyl ligands are lost by reductive
elimination or electrophilic attack. Unlike 5, 1 reacts
with phosphines, olefins, acetylenes, pyridine, and
water.
Higher acidity of the methylimido group in 1 leads to
facile deprotonation reactions. Triphenylphosphine,
pyridine, and water act as bases and deprotonate the
imido ligand forming the first osmium(IV) methylene-
amido complex, 2. This complex has been completely
characterized, and the data compare well with other
transition metal alkylideneamido species reported in the
literature. The complex is stable and can be reproto-
nated with strong acids to give 1.
In the reaction of 1 with water, hexamethyldisiloxane,
and small amounts of a bis(olefin)(imino)osmium com-
plex, 4, are also formed. Reductive elimination reac-
tions of 1 in the presence of ethylene lead to the
formation of a reduced imine complex, 4, in good yield.
Spectroscopic data for this complex correlate well with
those reported in the literature for both alkylideneimino
and ethylene complexes. Complex 2 does not react with
olefins under the same conditions, and this complex
cannot be an intermediate in the formation of 4 from 1.
The reaction of 1 with triphenylphosphine or with
ethylene leads to imido group transfer, forming a
phosphinimine or polymers of methylaziridine, respec-
tively. In the PPh3 reaction, an osmium phosphine
product has been isolated and characterized. No orga-
nometallic product has so far been isolated in imido
transfer to ethylene.
reacts bimolecularly to yield ethylene (eqs 1-3). Schrock
has reported evidence for the intermolecular coupling
of methylene ligands in Cp2Ta(dCH2)(CH3) to give an
ethylene complex.33
[CpOs(NCH3)(CH2SiMe3)2]+ + H2O f
Me3SiOH + Me3SiOH + Me4Si +
[(CH2)CpOs(NCH3)]+ (1)
2[(CH2)CpOs(NCH3)]+ f
CH2dCH2 + 2[CpOs(NCH3)]+ (2)
2CH2dCH2 + [CpOs(NCH3)]+ f
[CpOs(NCH3)(CH2dCH2)2]+ (3)
F or m a tion of P olya zir id in e. Certain transition
metal imido complexes react with alkenes to give
metallacyclic products. The reactions of Cp2ZrdNBut
with ethylene and with norbornene produced azametal-
lacyclobutanes by reversible, 2 + 2 cycloadditions. The
metallacycle derived from norbornene was isolated.10
Similarly, the (imido)vanadium complex V(NSiMe3)2-
(NHSiMe3)(OEt2) reacted reversibly with ethylene and
propylene to produce azametallacyclobutanes. These
were not isolated because they isomerized to vinyl
complexes, V(NSiMe3)(NHSiMe3)2(CHdCHR), at room
temperature.6 In neither system was the imido unit
transferred to the olefin to give organic products. Poly-
(imido)osmium complexes, such as Os(NCMe3)3(O), com-
bine with olefins by 3 + 2 cycloaddition reactions to give
isolable diazametallacyclopentanes.34 Reduction gives
the corresponding diaminoalkanes.
Exp er im en ta l Section
All reactions were conducted under N2 using standard air-
sensitive techniques. Anhydrous diethyl ether, THF, and
hexane were distilled from Na/benzophenone, while toluene
was distilled from Na. Methylene chloride and acetonitrile
were distilled from CaH2. The corresponding deuterated
solvents were dried in the same manner and were stored over
4 Å molecular sieves. [(η5-C5H5)Os(NCH3)(CH2SiMe3)2][BF4],
[(η5-C5H5)Os(15NCH3)(CH2SiMe3)2][BF4],18 [HPPh3][BF4], MeNd
PPh3, [MeN(H)PPh3]Br,37 and N-methylaziridine38 were pre-
pared according to literature procedures.
A 2 + 2 cycloaddition of ethylene to 1 would give
NMR spectra were recorded at 200 MHz on a Varian XL-
200 NMR spectrometer, at 300 MHz on a General Electric QE-
300 NMR spectrometer, at 360 MHz on a GE/Nicolet NT-360
[CpR2Os CH2CH2NCH3][SO3CF3]. Reductive elimina-
tion from this complex would produce N-methylaziridine
and a coordinatively unsaturated osmium(IV) species,
[CpOsR2][SO3CF3], but these products cannot survive
the reaction conditions. While there are, as yet, no
examples of the formation of aziridines from transition
metal imido complexes and olefins,35 the reverse of this
reaction has been demonstrated.36
(35) Stoichiometric transfer of
a derivatized nitride has been
demonstrated: Groves, J . T.; Takahashi, T. J . Am. Chem. Soc. 1983,
105, 2073-2074. There are examples of metal catalyzed aziridination
of olefins with RN3, RNIPh, and related reagents, but (imido)metal
complexes have not been observed in these systems. (a) Kahn, A. A.;
Kwart, H. J . Am. Chem. Soc. 1967, 89, 1951-1953. (b) Mansuy, D.;
Mayh, J .; Dureault, A.; Bedi, G.; Battioni, P. J . Chem. Soc., Chem.
Commum. 1984, 1161-1163. (c) Evans, D. A.; Faul, M. M.; Bilodeau,
M. T. J . Org. Chem. 1991, 56, 6744-6746. (d) Li, Z.; Conser, K. R.;
J acobsen, E. N. J . Am. Chem. Soc. 1993, 115, 5326-5327.
(36) Atagi, L. M.; Over, D. E.; McAlister, D. R.; Mayer, J . M. J . Am.
Chem. Soc. 1991, 113, 870-874.
(33) Schrock, R. R.; Sharp, P. R. J . Am. Chem. Soc. 1978, 100, 2389-
2399.
(34) (a) Chong. A. O.; Oshima, K.; Sharpless, K. B. J . Am. Chem.
Soc. 1977, 99, 3420-3426. (b) Schofield, M. H.; Kee, T. P; Anhaus, J .
T.; Schrock, R. R.; J ohnson, K. H., Davis, W. M. Inorg. Chem. 1991,
30, 3595-3604.
(37) Zimmer, H.; Singh, G. J . Org. Chem. 1963, 28, 483-486.
(38) (a) Stogryn, E. L.; Brois, S. J . J . Am. Chem. Soc. 1967, 89, 605-
609. (b) Elderfield, R. C.; Hageman, H. A. J . Org. Chem. 1949, 14,
605-615.

1628 Organometallics, Vol. 15, No. 6, 1996
Shapley et al.
NMR spectrometer, at 400 MHz on a General Electric 400
NMR spectrometer, and at 500 MHz on a General Electric GN-
500 NMR spectrometer. 31P NMR spectra were referenced to
external H3PO4. 1H NMR second-order splitting patterns were
simulated using ITRCAL program on a NIC1280 computer.
Electronic spectra were recorded on an HP 8452 diode array
UV/vis spectrometer. Gas chromatography was performed on
a Hewlett Packard 5790 Series gas chromatograph. IR spectra
were recorded on a Perkin-Elmer 1600 Series FTIR Spectrom-
eter. GCMS were obtained on a VG 70-VSE instrument with
EI/CI ion source. Elemental analyses were performed at the
University of Illinois School of Chemical Sciences Microana-
lytical Laboratory.
P r ep a r a t ion of 1. The yellow crystals of (η5-C5H5)-
Os(N)(CH2SiMe3)2 (0.045 g, 0.10 mmol) were dissolved in 1 mL
of CH2Cl2 in small vial along with a small stirring bar. A 10
equiv amount of MeOSO2CF3 (0.16 mL, 1.45 mmol) was then
added via syringe. The reaction mixture was stirred for 3 h
at room temperature, and the yellow-orange solution turned
darker orange-brown in color. The reaction mixture was then
cooled to -30 °C and stored at that temperature for 2 d. The
solution was filtered, and the solvent was removed under
vacuum. The resulting orange-brown oil was washed several
times with hexane. The product was crystallized from CH2-
Cl2 at -30 °C giving orange crystals of [CpOs(NCH3)(CH2-
SiMe3)2][SO3CF3] (0.056 g, 90% yield). IR (KBr pellet, cm-1):
3107 (m, Cp νCH), 2956 (m, νCH), 2896 (m, νCH), 1439 (m, δCH),
1420 m, 1278 sh, 1252 (s), 1226 m, 1161 (s, νSO), 1033 (νSO),
850 (s, νSiC), 833 (s, νSiC), 639 (s, Cp δCC). 1H NMR (500 MHz,
CD2Cl2, 18 °C; δ): 6.06 (s, 5 H, C5H5); 3.05 (d, J ) 12.9 Hz, 2
H, OsCHaHb); 2.78 (s, 3 H, OsNCH3); 2.49 (d, J ) 12.9 Hz, 2
H, OsCHaHb); 0.19 (s, 18 H, SiCH3). 13C{1H} NMR (125.8
MHz, CD2Cl2, 18 °C; δ): 96.2 (OsC5H5); 61.5 (OsNCH3); 1.5
(SiCH3); -6.3 (OsCH2). UV/visible spectrum (CH2Cl2, 1.1 ×
10-4 M, nm (ꢀ, M-1 cm-1): 232 (10 100), 276 (6119), 368 (sh).
P r ep a r a tion of 15N-1. This was prepared as above from
(η5-C5H5)Os(15N)(CH2SiMe3)2 and excess MeOSO2CF3. IR (KBr
pellet, cm-1): 3107 (m, Cp νCH), 2956 (m, νCH), 2896 (m, νCH),
1439 (m, δCH), 1420 m, 1278 sh, 1252 (s), 1226 m, 1161 (s, νSO),
1050 m, 1033 (νSO), 850 (s, νSiC), 833 (s, νSiC), 639 (s, Cp δCC).
1H NMR (200 MHz, CDCl3, 18 °C; δ): 6.09 (s, 5 H, OsC5H5);
3.00 (d, J ) 12.9 Hz, 2 H, OsCHaHb); 2.82 (d, 4.4 Hz, 3 H,
Os15NCH3); 2.46 (d, J ) 12.9 Hz, 2 H, OsCHaHb); 0.19 (s, 18
H, Si(CH3).
ether extract was filtered, and solvent was removed from the
filtrate. The residue was dissolved in hexane, the solution was
filtered, and solvent was removed from the filtrate under
vacuum. The residue was dissolved in a small amount of
hexane and the solution was cooled to -30 °C to give purple
crystals of 2 (0.020 g, 0.044 mmol, 49%).
The ether insoluble material from the reaction of 1 with
PPh3 was dissolved in CH2Cl2. Diethyl ether was added, and
the solution was cooled to -30 °C. Brown crystals of 3 were
collected by filtration and dried under vacuum (0.015 g, 0.019
mmol, 21%). 1H NMR (300 MHz, CD2Cl2, 18 °C; δ): 7.30 (m,
15 H, PPh), 4.94 (s, 5 H, C5H5), 3.85 (dd, J HH ) 15 Hz, J PH
)
10 Hz, 2 H, OsCHaHb), 1.95 (dd, J HH ) 15 Hz, J PH ) 31 Hz, 2
H, OsCHaHb), -0.16 (s, 18 H, SiCH3). 13C{1H} NMR (125.8
MHz, CD2Cl2, 18 °C; δ): 137.5 (d, J PC ) 14 Hz, PPh), 134.0 (d,
J PC ) 24 Hz, PPh), 128.9 (d, J PC ) 23 Hz, PPh), 128.8 (d, J PC
) 21 Hz, PPh), 83.21 (d, J PC ) 2.2 Hz, C5H5), 3.09 (d, J PC
)
3.1 Hz, OsCH2), 0.02 (SiCH3). 31P{1H} NMR (161.9 MHz, CD2-
Cl2, 18 °C; δ): 53.65 (OsPPh3).
PPh3 (0.033 g, 0.125 mmol) and 1 (0.011 g, 0.018 mmol) were
dissolved in 0.7 mL of CD2Cl2 in a 5 mm NMR tube. 13C and
31P NMR spectra showed resonances for unreacted PPh3 (31P
NMR, -4.91 ppm), 2, 3, [HPPh3][SO3CF3] (31P NMR, -0.15
ppm), and MeNdPPh3 (31P NMR, 15.76 ppm; 13C NMR, 180.8
ppm (d, J ) 24.7 Hz, NMe)).
P r ep a r a tion of (η5-C5H5)Os(15NdCH2)(CH2SiMe3)2 (15N-
2). This was prepared as above, by the reaction of [(η5-
C5H5)Os(15NCH3)(CH2SiMe3)2][SO3CF3] with PPh3 in CH2Cl2.
1H NMR (300 MHz, CDCl3, 18 °C; δ): 5.30 (s, 5 H, C5H5), 2.44
(d, J ) 12.8 Hz, 2 H, OsCHaHb), 2.00 (d, J ) 12.8 Hz, 2 H,
OsCHaHb), -0.09 (s, 18 H, SiCH3), -0.60 (d, J ) 3.1 Hz, 2 H,
Os15NdCH2);
Rea ction of 1 w ith H2O. Complex 1 (0.011 g, 0.018 mmol)
was dissolved in 0.75 mL of CD2Cl2 in a 5 mm NMR tube along
with 4 µL (0.2 mmol) of degassed water. The reaction was
monitored by 1H NMR spectroscopy. Complex 2 was observed
in the spectrum within 10 min. The starting material was
completely consumed in 2 h, giving 2 (δ 5.35, 2.51, 2.00, -0.07,
-0.56), SiMe4 (δ 0.0), Me3SiOH (δ 0.12), and a brown solid.
After 24 h, 2 was completely degraded. There was solid
deposited on the sides of the NMR tube, and the 1H NMR
showed SiMe4, Me3SiOH, Me3SiOSiMe3, and a small amount
of [(η5-C5H5)Os(NHCH2)(η2-C2H4)2][SO3CF3], 4 (vide infra).
GCMS of the reaction mixture confirmed the presence of
SiMe4, Me3SiOH, and Me3SiOSiMe3.
P r ep a r a tion of 2. NaH (0.10 g, 4.1 mmol) was added to a
stirred solution of 1 (0.020 g, 0.033 mmol) in 5 mL of THF.
The brown solution changed to deep purple within 30 s. The
mixture was filtered, solvent was removed from the filtrate
under vacuum, and the residue was dissolved in hexane and
purified by column chromatography using silylated silica gel/
hexane. The purple band was collected, and solvent was
removed under vacuum to give (η5-C5H5)Os(NCH2)(CH2SiMe3)2
in 94% yield (0.0142 g, 0.031 mmol) as a purple oil. Anal.
Calcd for C14H29NOsSi2: C, 36.73; H, 6.39; N, 3.06. Found:
C, 36.97; H, 6.52; N, 3.2. 1H NMR (300 MHz, CD2Cl2, 19 °C;
δ): 5.35 (s, 5 H, C5H5), 2.51 (d, J ) 12.9 Hz, 2 H, OsCHaHb),
2.00 (d, J ) 12.6 Hz, 2H, OsCHaHb), -0.07 (s, 18 H, SiCH3),
-0.57 (s, 2 H, NCH2). 13C{1H} NMR (125.8 MHz, CD2Cl2, 18
°C; δ): 128.9 (NCH2), 88.3 (C5H5), 2.4 (SiCH3), -19.5 (OsCH2).
13C NMR assignments were confirmed by APT and HETCOR
pulse sequences. IR (CH2Cl2 solution, cm-1): 3011 (w, Cp νCH),
2956 (s, νCH), 2928 (s, νCH), 2896 (m, νCH), 1606 (m, νNC), 1464
(w, δCH), 1378 (w, δCH), 1240 (m, δSiC), 853 (s, νSiC), 828 (s, νSiC).
UV-visible spectrum (CH2Cl2, nm (ꢀ)): 232 (17 546), 260
(12 542), 368 (380). Mass spectrum (EI, 70 eV, m/z): 459, 457
(M+)
Rea ction of 1 w ith P yr id in e. Complex 1 (0.011 g, 0.018
mmol) was dissolved in 0.75 mL of CD2Cl2 in a 5 mm NMR
tube along with 2 µL (0.024 mmol) of pyridine. The reaction
1
was monitored by H NMR spectroscopy. The starting mate-
rial was completely consumed in 2.5 h, giving 2 (δ 5.35, 2.51,
2.00, -0.07, -0.56) and small quantities of SiMe4 (δ 0.0), Me3-
SiCH2CH2SiMe3 (δ -0.03), and a brown solid. After 40 h, 2
was completely degraded and the reaction mixture consisted
of pyridine, SiMe4, soluble and insoluble osmium-containing
products, and a small amount of Me3SiCH2CH2SiMe3. GCMS
of the reaction mixture confirmed the presence of SiMe4 and
Me3SiCH2CH2SiMe3.
P r oton a tion of (η5-C5H5)Os(NdCH2)(CH2SiMe3)2 w ith
HBF 4. Complex 2 (8.6 mg, 0.019 mmol) was dissolved in CD2-
Cl2, and the purple solution was added to a 5 mm NMR tube.
HBF4 (50 µL of a 0.164 M solution in methylene chloride, 0.008
mmol) was added via syringe to the purple solution. The
solution immediately became orange in color.
A
1H NMR
spectrum was obtained after addition which showed a 1:1
mixture of 1 and 2.
Syn th esis of [(η5-C5H5)Os(HNCH2)(C2H4)2][SO3CF 3], 4.
Complex 1 (0.028 g, 0.046 mmol) was dissolved in 0.75 mL of
CD2Cl2. Excess ethylene (15 mL) was added slowly via syringe
over a period of 30 min. The reaction was monitored by 1H
NMR spectroscopy. After 4 days, 1 was completely converted
to 4. The solution was filtered, and the solvent was removed
from the orange-brown filtrate. The residue was extracted
Rea ction of 1 w ith P P h 3. A solution of PPh3 (0.048 g,
0.18 mmol) in 5 mL of CH2Cl2 was added to a solution of 1
(0.055 g, 0.09 mmol) in 20 mL of CH2Cl2. The reaction mixture
was stirred for 24 h, after which time the brown solution was
filtered. The solvent was removed under vacuum, and the
brown-yellow residue was extracted with ether. The purple

[CpOs(NCH3)(CH2SiMe3)2][SO3CF3]
Organometallics, Vol. 15, No. 6, 1996 1629
with hexane, and by diethyl ether, and then dried for 1 h under
vacuum to give 4 as a brown oil. Analytically pure crystals of
4 were obtained from thf/hexane solutions at -30 °C (0.016 g,
at 41 °C and stirred for 4 days. After cooling of the sample to
-78 °C, the ethylene was released. The vessel was warmed
to 22 °C. Solvent and volatile products were removed under
vacuum. The residue was extracted with CD2Cl2 and filtered.
1H NMR (400 MHz, CDCl3, 18 °C; δ): 7.84 (m); 7.56 (m); 2.91
(q, J ) 7.1 Hz); 1.42 (pentet, J ) 7.1 Hz); 1.27 (m); 0.84 (t, J
) 7.3 Hz). Mass spectrum (EI, 70 eV, m/z): 213, 170, 141,
123, 109, 97, 83, 77 (C6H5+), 69, 57 (CH2MeNCH2+), 42 (CH2-
NCH2+).
.
70%). Anal. Calcd for OsC11H16NO3SF3 OC4H8: C, 32.08; H,
4.31; N, 2.49. Found: C, 31.75; H, 4.49; N, 2.55. IR (CH2Cl2
solution, cm-1): 3155 (m, νNH), 3112 and 3067 (m, νCH), 2959
(m, νCH), 2930 (m, νCH), 1382 (s, νNC), 1166 (s, νSO), 1029 (s,
ν
SO), 639 (s, δCC). 1H NMR (500 MHz, CD2Cl2, 18 °C; δ): 12.15
(s, 1 H, HN), 7.95 (dd, J ) 12.9 Hz, J ) 12.9 Hz, 1 H, NCHaHb),
7.59 (dd, J ) 12.9 Hz, J ) 20.2 Hz, 1 H, NCHaHb), 5.39 (s, 5
H, C5H5), 3.18 (m, J ) 12.0 Hz, J ) 9.0 Hz, J ) -0.70 Hz, 4
H, CHaHbdCHb′CHa′), 3.02 (m, J ) 12.0 Hz, J ) 9.0 Hz, J )
-0.70 Hz, 4 H, CHaHbdCHb′CHa′). 13C{1H} NMR (125.8 MHz,
CD2Cl2, 18 °C; δ): 172.42 (NCH2), 84.64 (C5H5), 43.62
(CH2dCH2). 13C NMR assignments were confirmed by APT
and COSY pulse sequences.
Rea ction of N-Meth yla zir id in e w ith Eth ylen e. N-
Methylaziridine (0.006 g, 0.1 mmol) was dissolved in 3 mL of
CD2Cl2, and the solution was added to a medium-pressure
reaction vessel under nitrogen. The vessel was pressurized
with 1200 psi of ethylene at 31 °C and stirred for 4 days. After
cooling of the sample to -78 °C, the ethylene was released.
The vessel was warmed to 22 °C. Solvent and volatile products
were removed by vacuum distillation. The residue was
extracted with CD2Cl2 and filtered into an NMR tube. 1H
NMR (400 MHz, CDCl3, 18 °C; δ): 7.84 (m); 7.56 (m); 2.91 (q,
J ) 7.1 Hz); 1.42 (pentet, J ) 7.1 Hz); 1.27 (m); 0.84 (t, J )
7.3 Hz). Mass spectrum (EI, 70 eV, m/z): 213, 170, 141, 123,
109, 97, 83, 77 (C6H5+), 69, 57 (CH2MeNCH2+), 42 (CH2NCH2+).
Solutions of 4 in CD2Cl2 slowly isomerized. 1H NMR (400
MHz, CD2Cl2, 18 °C; δ): 12.69 (s, 1 H, HN), 8.16 (dd, J ) 13.0
Hz, J ) 13.0 Hz, 1 H, NCHaHb), 7.70 (dd, J ) 13.0 Hz, J )
20.3 Hz, 1 H, NdCHaHb), 5.61 (s, 5 H, C5H5), 3.48 (m, J )
12.0 Hz, J ) 9.0 Hz, J ) -0.70 Hz, 4 H, CHaHbdCHb′CHa′),
3.14 (m, J ) 12.0 Hz, J ) 9.0 Hz, J ) -0.70 Hz, 4 H,
CHaHbdCHb′CHa′).
Syn t h esis of [(η5-C5H 5)Os(15NH CH2)(C2H 4)2][SO3CF 3]
15N-4). This is the same as described above for 4 using [(η5-
Ack n ow led gm en t. We gratefully acknowledge the
financial support of the National Science Foundation
(Grants CHE 88-07707, CHE 93-08450) in support of
this work. NMR spectra were obtained on instruments
purchased through grants from the NIH and the NSF
(NIH PHS 1532135, NIH 1531957, and NSF CHE 85-
14500). High-resolution mass spectra were obtained in
the Mass Spectroscopy Laboratory, supported in part
by a grant from the NIH (GM 27029). The 70-VSE mass
spectrometer was purchased in part with a grant from
the NIH (RR 04648). P.A.S. gratefully acknowledges
financial support from an Alfred P. Sloan Foundation
Fellowship.
(
C5H5)Os(15NCH3)(CH2SiMe3)2][SO3CF3] and excess ethylene.
1H NMR (500 MHz, CD2Cl2, 18 °C; δ): 12.41 (ddd, J Nx ) 76.0
Hz, J xa ) 12.9 Hz, J xb ) 20.2 Hz, 1 H, Hx15NdCHaHb), 7.96
(td, J Na ) 3.2 Hz, J ab ) 12.9 Hz, J ax ) 12.9 Hz, 1 H,
synHx15NdCHaHb), 7.56 (dd, J ba ) 12.9 Hz, J bx ) 20.2 Hz, 1
H, anti-Hx15NdCHaHb), 5.35 (s, 5 H, C5H5), 3.15 (m, J AA′ ) 12.0
Hz, J AB′ ) 9.0 Hz, J AB ) -0.70 Hz, 4 H, CHAHBdCHB′CHA′),
3.02 (m, J BB′ ) 12.0 Hz, J A′B ) 9.0 Hz, J A′B′ ) -0.70 Hz, 4 H,
CHAHBdCHB′CHA′). 13C {1H} NMR (125.8 MHz, CD2Cl2, 18
°C; δ): 172.42 (HNdCH2), 84.64 (C5H5), 43.62 (CH2dCH2).
Rea ction of 1 w ith Eth ylen e u n d er P r essu r e. Complex
1 (0.055 g, 0.090 mmol) was dissolved in 3 mL of CD2Cl2, and
the solution was added to a medium-pressure reaction vessel
under N2. The vessel was pressurized with 760 psi CH2dCH2
OM950644T