Dissociative nucleophilic substitution of η2-olefin complexes via a novel η2-vinyl cation inTermediate

Article abstract of DOI:10.1021/ja960389j

A series of η²-[Os(NH₃)₅(vinyl ether)]²⁺ complexes have been prepared by three independent methods that involve direct coordination of a vinyl ether, alcohol addition to an η²-alkyne complex, or nucleophilic substitution of an η²-vinyl ether species. In the presence of an acid catalyst, the vinyl ether ligand undergoes a novel acid-catalyzed substitution reaction at the α-carbon with a broad range of nucleophiles that includes alcohols, amines, carboxylates, hydrides, silylated enols, nitriles, phosphines, and dialkyl sulfides. These reactions appear to proceed through an elimination-addition process where the first step is loss of an alcohol to form an η²-vinyl cation intermediate. In cases where the α-carbon bears an alkyl group, an η²-vinyl cation species can be isolated and characterized. For example, protonation of [Os(NH₃)₅(η²-2-methoxypropene)]²⁺ (3) in neat HOTf allows the characterization of the substitution reaction intermediate η²-[Os(NH₃)₅(C₃H₅)]³⁺ (32), formally a metallocyclopropene that behaves chemically like a vinyl cation. In contrast, when the α-carbon of the vinyl ether bears a hydrogen such as with [Os(NH₃)₅(η²-ethoxyethene)]²⁺ (1), the hypothetical vinyl cation intermediate, in absence of a suitable nucleophile, undergoes an intramolecular 1,2-hydrogen shift to yield the Fischer carbyne [(NH₃)₅Os≡CCH₃]³⁺ (33). Examples of nucleophilic substitution reactions for other types of η²-[Os(NH₃)₅(olefin)](n+) complexes are also demonstrated.

Full text of DOI:10.1021/ja960389j

5
672
J. Am. Chem. Soc. 1996, 118, 5672-5683
2
Dissociative Nucleophilic Substitution of η -Olefin Complexes
2
via a Novel η -Vinyl Cation Intermediate
Huiyuan Chen and W. Dean Harman*
Contribution from the Department of Chemistry, UniVersity of Virginia,
CharlottesVille, Virginia 22901
X
ReceiVed February 6, 1996
2
2+
Abstract: A series of η -[Os(NH3)5(vinyl ether)] complexes have been prepared by three independent methods
2
that involve direct coordination of a vinyl ether, alcohol addition to an η -alkyne complex, or nucleophilic substitution
of an η -vinyl ether species. In the presence of an acid catalyst, the vinyl ether ligand undergoes a novel acid-
2
catalyzed substitution reaction at the R-carbon with a broad range of nucleophiles that includes alcohols, amines,
carboxylates, hydrides, silylated enols, nitriles, phosphines, and dialkyl sulfides. These reactions appear to proceed
2
through an elimination-addition process where the first step is loss of an alcohol to form an η -vinyl cation
2
intermediate. In cases where the R-carbon bears an alkyl group, an η -vinyl cation species can be isolated and
2
2+
characterized. For example, protonation of [Os(NH3)5(η -2-methoxypropene)] (3) in neat HOTf allows the
2
3+
characterization of the substitution reaction intermediate η -[Os(NH3)5(C3H5)] (32), formally a metallocyclopropene
that behaves chemically like a vinyl cation. In contrast, when the R-carbon of the vinyl ether bears a hydrogen such
as with [Os(NH3)5(η -ethoxyethene)] (1), the hypothetical vinyl cation intermediate, in absence of a suitable
nucleophile, undergoes an intramolecular 1,2-hydrogen shift to yield the Fischer carbyne [(NH3)5OstCCH3] (33).
Examples of nucleophilic substitution reactions for other types of η -[Os(NH3)5(olefin)] complexes are also
2
2+
3
+
2
n+
demonstrated.
Introduction
Nucleophilic substitution at a vinylic carbon is considerably
more difficult to carry out than is the corresponding reaction
for a saturated system.1 However, coordination of the olefin
to an electron-withdrawing transition metal (e.g., PdCl2, [FeCp-
+
(
CO)2] ) activates it toward nucleophilic addition, and this
principle is the bedrock for some of the most useful organo-
metallic processes in organic synthesis.2 In contrast, the
chemistry of olefins coordinated to an electron-rich transition
metal is less understood. In this paper, we describe our findings
concerning the nucleophilic substitution of olefins bound to the
π-base pentaammineosmium(II), a system showing an unusual
ability to activate various unsaturated ligands toward reactions
with electrophiles.3 Whereas nucleophilic substitution for η -
olefin complexes is typically initiated by nucleophilic attack
2
(
path A, Figure 1), we find that substitution for the pentaam-
Figure 1. Complementary approaches to nucleophilic substitution for
an η -coordinated olefin.
mine(olefin)osmium system proceeds through the electrophile-
induced removal of the leaving group (e.g., alkoxide or
carboxylate) followed by nucleophilic addition to a vinyl cation
intermediate (path B, Figure 1).
2
through three independent synthetic routes (Figure 2). Analo-
2
gous to that reported for the synthesis of η -furan and dihy-
2
+
drofuran complexes, [Os(NH3)5(OTf)] may be reduced (Zn/
Results
0
Hg or Mg ) in the presence of an excess of vinyl ether in the
Syntheses of Vinyl Ether Complexes. Complexes of the
appropriate solvent to generate the vinyl ether complex directly.4
2
form [Os(NH3)5(η -vinyl ether)] (OTf)2 can be synthesized
Using this method, pentaammineosmium(II) complexes of
ethoxyethene (1), 2-methoxypropene (3), 3,4-2H-dihydropyran
X
Abstract published in AdVance ACS Abstracts, June 1, 1996.
(1) Patai, S. The Chemistry of Alkenes; John Wiley & Sons: London,
(4), and 1-ethoxypropene (cis, 7a; trans, 7b) were prepared with
1
964; Chapter 8.
2) For the general chemistry of transition metal-olefin complexes,
yields ranging from 70% to 95%. In the latter case, the ligand
is commercially available as a mixture of cis and trans isomers
in a 2:1 ratio, and after complexation and isolation this
(
see: (a) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles
and Applications of Organotransition Metal Chemistry, 2nd ed.; University
Science Books: Mill Valley, CA, 1987; Chapters 7-9, 16, 17. (b) Crabtree,
R. H. The Organometallics Chemistry of the Transition Metals; John Wiley
1
diastereomeric ratio was identical ( H NMR). Accordingly, the
&
Sons: New York, 1994; Chapters 5, 6, 11, 14. (c) Pearson A. J. Metallo-
Organic Chemistry; John Wily & Sons: New York, 1985; Chapter 5.
3) (a) Harman, W. D.; Taube, H. J. Am. Chem. Soc. 1987, 109, 1883.
b) Kopach, M. E.; Harman, W. D. J. Am. Chem. Soc. 1994, 116, 6581. (c)
stereochemistry for 7a and 7b has been assigned as cis and trans,
respectively, consistent with the original isomeric composition
(
2
of the ligand. The ruthenium analog of 1, [Ru(NH3)5(η -
(
Hodges, L. M.; Gonzalez, J.; Koontz, J. I.; Myers, W. H.; Harman, W. D.
J. Org. Chem. 1995, 60, 2125. (d) Gonzalez, J.; Koontz, J. I.; Myers, W.
H.; Hodges, L. M.; Sabat, M.; Nilsson, K. R.; Neely, L. K.; Harman, W.
D. J. Am. Chem. Soc. 1995, 117, 3405. (e) Spera, M. E.; Harman, W. D.
Organometallics 1995, 14, 1559.
(ethoxyethene)](OTf)2 (8), was synthesized in ∼70% yield by
a procedure similar to that used for the osmium compound 1.
(4) Harman, W. D.; Hasegawa, T.; Taube, H. Inorg. Chem. 1991, 113,
453.
S0002-7863(96)00389-7 CCC: $12.00 © 1996 American Chemical Society

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5673
2
Figure 2. Methods for the synthesis of η -pentaammineosmium(II)
2
+
3 5 2
vinyl ethers ([Os] ) [Os(NH ) ](OTf) ).
2
An alternative method to prepare η -vinyl ether complexes
2
is the nucleophilic substitution of η -pentaammmine(olefin)-
osmium complexes (described herein). For example, when the
2
2+
complex [Os(NH3)5(η -ethoxyethene)] (1) is dissolved in
methanol and treated with a catalytic amount of HOTf, [Os-
Figure 3. Reaction of the 3-butyn-1-ol complex of pentaammine-
osmium(II) (prepared in situ) in the presence of acid.
2
(
NH3)5(η -methoxyethene)](OTf)2 (2) is recovered in analyti-
1
13
cally pure form. H and C NMR spectra of 2 closely resemble
those of 1 except that the ethoxy signals have been replaced
with a methoxy resonance. Finally, as has been previously
reported, alkyne complexes may undergo addition of alcohols
carbon of the ethoxy group lies well outside the plane formed
by the oxygen and vinyl carbons, a geometric arrangement that
rules out any significant π interaction between the oxygen and
2
5
2
to form η -vinyl ether complexes. For example, the 2-butyne
the vinyl group. Spectroscopic data for the η -vinyl ether
complex [Os(NH3)5(CH3CCCH3)]2 readily forms the η -cis-
-methoxybut-2-ene complex when allowed to stand in metha-
nol. In an interesting variation of this reaction, when {Os-
+
2
complexes show H and C resonances of the coordinated vinyl
1
13
2
2
group shifted significantly upfield as is typical for η -olefin
complexes. In general, the trans vicinal coupling constants for
the vinyl protons sharply decrease (Jtrans ) ∼6-9 Hz) upon
coordination relative to the free ligand (12-15 Hz) while cis
coupling constants suffer only a modest decrease. In the case
of complexes 1, 2, and 7a,b, trans vicinal coupling constants
2
+
(
NH3)5} is generated in the presence of 3-butyn-1-ol and
methanol, a mixture of two products is isolated in a 3:2 ratio.
1
A H NMR spectrum of the major product shows a methoxy
resonance, and a pair of olefinic protons, whose small coupling
8
constant (J ) 2.7 Hz) indicates their geminal relationship. A
are especially low (Jtrans ) ∼6 Hz). In contrast to the open-
1
3
2
quaternary C resonance at 91.4 ppm and a methylene signal
chain η -vinyl ether complexes, the five-membered cyclic vinyl
2
at 38.0 ppm confirm the assignment of 9 as an η -3-methoxy-
ether complexes 5 and 6 actually show a slight increase in the
cis coupling constant upon coordination. As a result, vicinal
coupling constants or chemical shifts are so similar for different
diastereomers that these data are no longer reliable indicators
of stereochemistry. However, careful comparison with known
systems (e.g., 7a and 7b; Vide infra) allows assignment in many
cases (Tables 1 and 2).
3
-buten-1-ol species (Figure 3), a product (9) resulting from
protonation of the alkyne at C(4) followed by addition of
methoxide at C(2). The minor product 10 was determined not
to be a regioisomer of 9, but rather the Fischer carbene shown
in Figure 3, a product resulting from C(3) protonation of the
2
-butyne ligand. In addition to the above general methods,
2
2
organic transformations on the uncoordinated portion of η -furan
complexes have led to a wide range of cyclic vinyl ether
complexes of pentaammineosmium(II).6
Nucleophilic Substitution Reactions of η -Vinyl Ether
2
Complexes. The η -vinyl ether complexes of pentaammine-
osmium(II) are inert to nucleophiles such as NaOCH and NBu -
3
4
A single crystal of compound 1 was structurally analyzed
using X-ray diffraction.7 Due to extensive internal disorder in
the crystal, the optimized structural parameters calculated are
BH4 under basic conditions. However, addition of a catalytic
amount of Lewis or Br o¨ nsted acid activates these complexes
toward nucleophilic substitution and these reactions are sum-
marized in Figure 4.
2
not meaningful; however, the η -binding mode of the vinyl ether
was unambiguously determined. In addition, the methylene
Oxygen and Sulfur Nucleophiles. When the ethyl vinyl
ether complex 1 in methanol is treated with catalytic HOTf,
facile exchange of the ethoxy group for a methoxy group occurs.
(
5) Harman, W. D.; Dobson, J. C.; Taube, H. J. Am. Chem. Soc. 1989,
11, 3061.
6) (a) Chen, H.; Hodges, L. M.; Liu, R.; Stevens, W. C.; Sabat, M.;
1
Addition of a mixture of CH2Cl2 and Et2O precipitates the
(
1
Harman, W. D. J. Am. Chem. Soc. 1994, 116, 5499. (b) Liu, R.; Chen, H.;
Harman, W. D. Organometallics 1995, 14, 2861.
methyl vinyl ether complex 2 as a single product (72%).
H
13
2
and C NMR data for all of the η -vinyl ether complexes
discussed herein are reported in Tables 1 and 2. When the
(
7) Crystallographic data for C6H23F9N5O7S2Os: Mr ) 702.6, monoclinic,
9
space group C2/c (no. 15), a ) 21.719 Å, b ) 7.917(4) Å, c ) 28.746 Å,
3
-3
2:1 mixture of cis- and trans-1-ethoxypropene complexes 7a
and 7b is treated with catalytic acid (HOTf, 0.5 equiv, 0.05 M)
â ) 104.86°, V ) 4777(3) Å , Z ) 8, dcalcd ) 1.95 g cm , T ) -100 °C.
The structure was solved by direct methods and refined to an R of 0.054
(
Rw ) 0.067) for 1967 absorption-corrected reflections with I > 3σ(I).
Unresolvable disorder of the organic ligand prevented any detailed analysis
of its geometry.
(8) (a) Culter, A.; Raghu, S.; Rosenblum, M. J. Organomet. Chem. 1976,
108, 93. (b) Thyret, H. Angew. Chem., Int. Ed. Engl. 1972, 11, 520.

5
674 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Chen and Harman
Table 1. 1H NMR Data for Selected Vinyl Ether Complexes and Their Organic Ligandsa
δ (ppm)
Hb
OR
β
α
Ha
Hc
compound
trans-NH
3
/cis-NH
3
H
a
H
b
H
c
J
a,b (Hz)
J
a,c (Hz)
J
b,c (Hz)
+
[
[
[
[
[
[
[
[
[
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
3
3
3
3
3
3
3
3
)
)
)
)
)
)
)
)
5
5
5
5
5
5
5
5
(ethoxyethene)]2 (1)
4.08/3.00
4.07/3.00
4.07/3.03
4.03/3.02
4.02/3.02
4.02/2.85
3.99/2.97
3.99/2.97
3.57/1.82
2.85
2.84
2.91
3.35
3.49
4.85
3.44
3.06
3.09
3.25
5.70
5.69
2.4
2.5
2.0
4.8
5.1
6.3
6.3
2
+
(methoxyethene)] (2)
2
+
(2-methoxypropene)] (3)
(4,5-6H-dihydropyran)] (4)
(4,5-dihydrofuran)] (5)
(furan)] (6)
(cis-1-ethoxypropene)] (7a)
2
+
6.05
6.10
7.24
5.52
5.63
5.89
6.46
6.0
3.6
3.3
5.2
2
+
2
+
2
+
2
+
(trans-1-ethoxypropene)] (7b)
3.12
3.08
4.16
3.87
6.0
8.7
14.4
2
+
Ru(NH
3
)
5
(ethoxyethene)] (8)
2.84
3.94
3.85
4.59
4.95
6.44
4.27
2.4
1.5
1.8
5.1
6.9
ethoxyethene
2
3
1
-methoxypropene
,4-2H-dihydropyran
,2-dihydrofuran
6.27
6.32
7.54
5.93
6.17
6.0
2.7
1.4
6.7
furan
cis-1-ethoxypropene
trans-1-ethoxypropene
4.71
12.8
a
Recorded in acetonitrile-d
solution at 22 °C unless otherwise noted. Complexes 1-8 are triflate salts (OTf-).
3
Table 2. 13C NMR and Electrochemical Data for Selected Vinyl Ether Complexes and Their Organic Ligands
of complex (ppm) of free ligands (ppm)
δ
C
δ
C
reduction potential
compound
CR
Câ
CR
Câ
E
p,a (V)
E
1/2 (V)
+
[
[
[
[
[
[
[
[
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
Os(NH
3
3
3
3
3
3
3
)
)
)
)
)
)
)
5
5
5
5
5
5
5
(ethoxyethene)]2 (1)
93.30
94.95
89.92
95.44
98.64
92.84
95.24
112.65
33.05
35.63
40.00
37.64
48.96
38.55
39.75
49.85
152.80
161.63
145.00
147.74
143.44
146.56
147.57
152.80
86.75
81.36
101.57
100.46
110.26
100.82
98.84
0.67
0.63
0.49
0.63
2
+
(2-methoxypropene)] (3)
(4,5-6H-dihydropyran)] (4)
(4,5-dihydrofuran)] (5)
(furan)] (6)
(cis-1-ethoxypropene)] (7a)
2
+
2
+
2
+
0.67
1.14
2
+
0.66
0.66
2
+
(trans-1-ethoxypropene)] (7b)
2
+
Ru(NH
3
)
5
(ethoxyethene)] (8)
86.75
a
solution at 22 °C. b Recorded by cyclic voltammetry in acetonitrile/
3
The data for the complexes and their ligands are recorded in acetonitrile-d
0.5 M TBAH, 100 mV/s, NHE.
∼
in ethanol, the two diastereomers rapidly interconvert, resulting
in a 1:1 equilibrium mixture. Treatment of either the 2:1 or
the 1:1 mixture of 7a and 7b with HOTf (0.5 equiv, 0.05 M) in
methanol (2 h, 22 °C) results in a 1:1 mixture of cis- and trans-
η -1-methoxypropene complexes 12a and 12b. Next, this
reaction is repeated using a 1:1 mixture of 7a and 7b (32.4 mg,
with ether resulted in precipitation of a solid that was collected
and dried in Vacuo (70% recovery). Spectroscopic analysis
reveals that the isolated product was the dihydrofuran starting
material 5 exclusively! If, prior to precipitation, the acid in
solution was neutralized with H u¨ nig’s base, the isolated product
2
1
mixture was a 1:2 ratio of 13a and 13b ( H NMR spectra in
0
.049 mmol) with a lower concentration of a Lewis acid (BF3‚
CD CN), identical to that seen in acidic methanol-d solution.
3
4
1
OEt2, 0.01 M), and monitored by H NMR (methanol-d4). After
Finally, when this reaction was repeated at -40 °C for 3 days,
then quenched with base, and precipitated with Et2O, the sole
product isolated (62%) was the trans isomer 13b.
10 min, an absorption spectrum shows approximately a 0:0.6:
1.0:0.4 ratio of the four vinyl ether complexes 7b, 7a, 12b, and
12a involved in the reaction. Comparison of the following
The reaction of the ethoxyethene complex 1 with water in
spectra taken over a period of 2 h shows that while nucleophilic
substitution of the trans isomer 7b and formation of the trans
isomer 12b is essentially complete in 10 min, complete
consumption of the cis isomer 7a takes roughly 1 h (ktrans/kcis
2
acidic solution results in the formation of the η -vinyl alcohol
complex 11, and this cation is precipitated out of the reaction
solution as the tetraphenylborate salt. Three vinyl protons of
1
1 show a clear ABX coupling pattern, but the R-proton also
>
5), and during this period the cis product 12a is formed. In
weakly couples to the hydroxyl proton at 3.83 ppm (J ) 3.9
2
a separate series of experiments, the reaction of the η -
dihydrofuran complex 5 with methanol was monitored in
methanol-d4 over a period of 1 week (0.3 equiv of HOTf, ∼22
1
3
Hz). C NMR data for 11 show two olefinic (coordinated)
resonances at 88.4 and 32.3 ppm, values similar to those
observed for the vinyl ether 1. We note here that spectroscopic
°
C). A comparison of the spectra indicates that, after 9 h, 90%
2
data for this η -enol complex (11) differ significantly from those
of the starting material is converted to a 1:2 thermodynamic
mixture of 13a and 13b, two new vinyl ether species spectro-
scopically characterized as cis- and trans-4-methoxy-3-buten-
1
of other late transition metal cationic complexes. H NMR data
2
+
for the latter compounds (e.g., [FeCp(CO)2(η -ethenol)] )
typically show a broadened hydroxyl proton and an A2X splitting
pattern for the vinyl protons, due to a rapid acid-base
equilibrium between the vinyl alcohol and its â-oxoalkyl
1-ol complexes, respectively. Treatment of this reaction mixture
(
9) The assignments of the coordinated carbons R or â to the oxygenated
substituent were determined through DEPT experiments, and the assign-
ments for the respective protons were confirmed by proton-proton
decoupling and HETCOR procedures.
10
isomer.
When 1 is combined with tert-butyldimethylsilyl triflate

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5675
Figure 4. Representative acid-catalyzed nucleophilic substitution
2
reactions for the η -vinyl ether complex 1.
(TBSOTf) (1 equiv, 22 °C, CH3CN) in the presence of excess
ammonium acetate, no reaction occurs. However, if the
complex 1 is dissolved in acetic acid and allowed to stand (40
min), addition of a mixture of CH2Cl2 and Et2O quantitatively
precipitates a new olefin complex (14, 92%). Relevant NMR
Figure 5. Formation of vinylacetimidate and vinylacetamide complexes
from vinyl ether precursors and acetonitrile.
data for 14 include a methyl proton resonance at 1.98 ppm and
carbonyl 13C signal at 174.1 ppm. Complete spectroscopic and
2
combustion analysis reveals that the complex 14 is the η -
min) followed by precipitation with CH2Cl2 and Et2O produces
carbomethoxyethene complex of pentaammineosmium(II). Re-
peating the reaction in acetic acid for the 2-methoxypropene
2
the η -enamine complexes 17 and 18, respectively. Repeating
this reaction with pyridine as the nucleophile affords the
corresponding vinylpyridinium complex 19 (Vide infra).12 When
triphenylphosphine is combined with a Lewis acid and the vinyl
2
complex 3 gives a similar outcome, the η -isopropenyl acetate
species 15.
Treatment of the vinyl ether complex 1 with a stoichiometric
amount of TBSOTf in the presence of dimethyl sulfide also
2
ether complex 1 or 3 in acetonitrile, the corresponding η -
vinyltriphenylphosphonium complexes 20 and 21 are formed
in good yield.
1
results in a facile nucleophilic substitution reaction. A H NMR
2
spectrum of the product η -vinyldimethylsulfonium complex 16
When complex 1 is treated with 1 equiv of HOTf in
features trans- and cis-ammine resonances that are shifted
downfield relative to those of more typical olefin complexes of
1
acetonitrile, a new species (22) is recovered, which gives a H
NMR spectrum similar to that of 1, but with a new methyl
resonance at 2.38 ppm and a broad singlet at 9.57 ppm. Signals
for the vinyl protons and cis/trans-ammines are shifted down-
field by 0.2-0.8 ppm relative to those of starting material 1. A
complete spectroscopic analysis reveals the structure of the
organic ligand as protonated acetimidate (Figure 5). When this
1
pentaammineosmium(II). Two well-resolved methyl signals ( H
13
and C NMR) indicate a relatively high inversion barrier (>10
11
kcal/mol) for the pyramidal sulfonium center. Over the course
of 10-15 days, the complex 16 decomposes in CH3CN solution,
yielding only paramagnetic compounds; however, it is stable
for months when kept in the solid state at -20 °C.
1
reaction is repeated in CD3CN, the product 22-d3 has a H NMR
Nitrogen and Phosphorus Nucleophiles. Dissolving vinyl
ether complex 1 or 3 in a mixture of acetic acid and aniline (30
spectrum that is missing only the methyl signal at 2.38 ppm
relative to that of 22, an observation verifying the incorporation
of acetonitrile in the product. Irradiation of the methyl signal
at 2.38 ppm for 22 causes a 9% NOE enhancement of the NH
feature, indicating that the ligand is exclusively in its Z-form.13
(
10) Milstein, D. In The Chemistry of Enols; Rappoport, Z. V. I., Ed.; J.
Wiley & Sons: New York, 1990; Chapter 12.
11) Theoretical calculations and experimental findings (synthesis of
(
optically active sulfonium salt, and their crystal structure data) both confirm
a pyramidal conformation for sulfonium salt. The barrier for inversion is
calculated to be 24 kcal/mol with d orbitals and 13.5 kcal/mol without d
orbitals. See: (a) Simonetta, M.; Gavezzotti, A. In The Chemistry of the
Sulphonium Group; Stirling, C. J. M., Ed.; J. Wiley & Sons: New York,
(12) This method of preparation for the vinylpyridinium complex 19 was
found to be inferior to that reported in the Experimental Section.
(13) Fodor, G.; Phillips, B. A. In The Chemistry of Amidines and
Imidates; Patai, S., Ed.; J. Wiley & Sons: New York, 1975; Chapter 2, pp
132-138.
1
981; Part 1, Chapter 1, pp 1-14. (b) Andersen, K. K. Ibid.; Chapter 10.

5
676 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Chen and Harman
2
rapidly reacts with methanol to form the η -methyl vinyl ether
2
complex 2. The η -vinyl acetate complex 14, although stable
in methanol alone, rapidly reacts with the addition of acid,
generating 2 and acetic acid as the only products. The
2
η -vinyldimethylsulfonium complex readily reacts with pyridine
2
to give η -N-vinylpyridinium complex 19 as a single product.
2
In contrast to the above results, when the η -vinylphosphonium
complex 20 was combined with excess methanol in acetonitrile,
and kept at 60-70 °C for 12 h, no reaction occurred. Similarly,
2
under all the reaction conditions tried, the amine group of η -
N-vinylphenylamine complex 17 does not exchange with
1
13
2
methanol. H and C NMR data for the [Os(NH3)5(η -
n+
olefin)] complexes reported herein are collected for compari-
son in Tables 3 and 4. Proton and carbon assignments have
1
1
been made, where possible using H/ H coupling, DEPT, and
HETCOR data.
2
Figure 6. Reactions of the η -vinyl acetate complex 14 with carbon
nucleophiles.
Isolation and Characterization of Vinyl Cation. Protona-
tion of the vinyl ether complex 3 with a stoichiometric amount
of HOTf in acetonitrile, either at room temperature or at -40
°C, produces a dark peach solution. The product 32, precipitated
as its triflate salt by a mixture of Et2O and CH2Cl2, shows a
pair of broadened resonances at 4.35 (3H) and 4.11 (12H) ppm
A similar nucleophilic substitution is postulated for the reaction
of 2,3-η -6H-4,5-dihydropyran (4), and complexes of 2,3-
dihydrofuran (5) and 3,4-η -1-hydroxy-3-methoxy-3-buten-1-
ol (9). In these cases, η -cyclic imidate complexes 23, 24, and
2
2
2
(CD3CN) corresponding to the trans- and cis-ammines, signals
2
5 are formed according to Figure 5. These products are
1
13
that are shifted unusually far downfield and appear unusually
close together relative to those of simple olefin complexes.16
In addition to these signals, two slightly broadened singlets are
characterized by H and C NMR, DEPT, and HETCOR, and
their spectroscopic data are consistent with those of known
organic imidates. Finally, when a mixture of 13a and 13b is
treated with 1 equiv of HOTf in CH3CN, the cyclic imidate 24
is the only product isolated.
In a variation of the imidate reaction above, an acetonitrile
solution of 1 was treated with 1 equiv of triflic acid and an
excess of water. The resulting compound, a protonated viny-
lacetamide (26), is then deprotonated (H u¨ nig’s base) to yield
1
present in the H NMR spectrum at 3.12 ppm (2H) and 2.37
ppm (3H). The same product can also be generated from 3
and neat triflic acid and isolated by precipitation in Et2O. The
low solubility of 32 and its highly reactive nature prevented
1
3
the convenient characterization by C NMR in acetonitrile,
acetone, or DMF. Thus, triflic acid-d, was used as the solvent
1
3
for C NMR and 2D NMR characterization of 32 (Figure 7).
Addition of 3 (48.7 mg) to a sample of triflic acid-d (725 mg)
rapidly shows the dark peach color earlier observed in aceto-
2
the corresponding η -N-vinylacetamide complex 27 in overall
8
1% yield.
2
Hydride Nucleophiles. Although η -vinyl ether complexes
1
nitrile. Comparison of the H NMR spectrum of the reaction
of pentaammineosmim(II) fail to react with Et3SiH or Bu4NBH4
in CH3CN alone, when the vinyl ether complex 1 is combined
with a mixture of triethylsilane and TMSOTf, nucleophilic
substitution readily occurs. The product obtained is identical
mixture with that of methanol in triflic acid confirmed that
methanol is produced as a byproduct. DEPT and HETCOR
data confirm that the ligand in 32 contains one methyl group,
one methylene group, and a downfield quaternary carbon (299.9
ppm). These data are most consistent with a dihapto-
coordinated isopropenyl cation resulting from the loss of
methanol from protonated 3 (Figure 8). When a solution of 32
in acetonitrile is treated with a nucleophile (e.g., methanol or
aniline), the corresponding addition product (i.e., 3 or 18) rapidly
forms in good purity. When a solution of 32 is allowed to stand
in triflic acid-d, for a 2-day period, the methyl group partially
undergoes deuterium exchange (∼50%) while the methylene
group remains fully intact.
2
to the η -ethylene complex 28, previously prepared by direct
reduction of [Os(NH3)5(OTf)](OTf)2 in DME solution saturated
with ethylene.14 However, both the purity and yield of the
ethylene complex 28 are significantly improved by this new
procedure. [Os(NH3)5(η -propene)](OTf)2 (29) is prepared by
a similar reaction starting from compound 3. Spectra for
compound 29 are consistent with those previously reported by
2
1
5
Shepherd et al.
Carbon Nucleophiles. When 1 or 3 is combined with a
Lewis acid and carbon nucleophile such as a silyloxy or alkoxy
vinyl ether, only intractable mixtures or starting materials are
obtained. However, the addition of carbon nucleophilies was
ultimately achieved by utilizing olefin complexes with better
Formation of Osmium Carbynes. Despite the similarities
between the vinyl ether complexes 1 and 3, protonation of these
complexes in neat HOTf has an entirely different outcome.
Spectroscopic data for the new material 33 include a cis-ammine
2
leaving groups. When the η -carbomethoxyethene complex 14
13
resonance downfield of the trans-ammine signal, and a
C
is combined with 2-(trimethylsiloxy)propene or methyl tri-
methylsilyl ketene dimethyl acetal (1.0-2.0 equiv, CH3CN) and
a catalytic amount of a Lewis acid (TMSOTf, 0.1-0.5 equiv,
40 °C), nucleophilic substitution readily occurs at the coor-
dinated R-carbon to generate alkyl-substituted ethylene com-
plexes 30 and 31, respectively (Figure 6).
Osmium(II) complexes of vinylsulfonium (16) and vinyl
acetate (14) were found to be particularly useful as synthons to
other substituted olefins. In acetonitrile solution, compound 16
resonance at 296.1 ppm, features that are diagnostic for a
6a,17
pentaammineosmium carbyne complex (Figure 8).
Taken
together with the appearence of a single methyl group (DEPT),
-
compound 33 is unambiguously assigned as [Os(NH3)5(tCCH3)]-
18
(
OTf)3. In order to gain some insight into the mechanism of
carbyne formation, complex 1 was treated with DOTf and then
(
16) π-bound olefin, ketone, and iminium complexes of pentaammin-
eosmium(II) in every case documented show cis- and trans-ammine
resonances separated by >1 ppm.
(17) Hodges, L. M.; Sabat, M.; Harman, W. D. Inorg. Chem. 1993, 32,
(
14) Harman, W. D. Ph.D. Dissertation, Stanford University, Stanford,
CA, 1987.
15) Elliott, M. G.; Shepherd, R. E. Inorg. Chem. 1988, 27, 3332.
371.
(18) Carbyne 33 can also be generated from the protonation of the
η2 vinylacetate complex 14 with neat HOTf.
-
(

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5677
Table 3. 1H NMR Data for Various Dihapto-Coordinated Olefin Complexes of Pentaammineosmium(II)
δb (ppm)
a
a
compd
R-substituent
H
a
H
b
H
c
trans-NH
3
cis-NH
3
J
a,b (Hz)
J
a,c (Hz)
Jb,c (Hz)
2
2
3
8
9
1
1
1
4
7
7
2
9
0
6
H
CH
C(CH
OCH
OH
OOCCH
NHPh
NHCOCH
3
HNdC(OEt)(CH )
pyridine
PPh
S(CH
3.01
3.06
3.42
3.07
2.99
3.39
3.17
3.25
3.86
4.94
4.81
4.15
4.11
4.01
4.06
4.08
3.70
4.16
4.04
4.03
4.30
4.48
5.08
4.51
2.95
2.93
3.10
3.00
2.78
3.11
3.06
3.19
3.21
3.26
3.71
3.40
3
2.81
2.95
2.85
2.76
3.20
3.12
3.05
3.49
4.04
4.75
3.95
3.34
3.57
5.70
5.93
6.92
5.30
5.98
5.90
6.56
5.08
4.73
∼0
1.5
2.4
2.9
3.3
2.0
2.1
3.6
5.4
9.0
9.0
4.8
5.2
5.9
8.2
7.2
6.9
7.2
9.0
10.2
6.3
6.9
5.9
6.7
7.2
7.2
7.4
3
)
2
COCH
3
3
2
CH
c
1
1
1
2
2
1
2
1
3
3
d
3
3
)
2
3.9
7.8
7.8
a
b
H
a
and H
b
are located on the â-carbon; however, their geometrical orientation is unknown. Recorded in acetonitrile-d
3
solution as a triflate
-
c
-
4
salt. d Due to the overlap of peaks, coupling constants are not available.
salt (OTf ), at 22 °C unless otherwise noted. 11 as a BPh
Table 4. 13C NMR and Electrochemical Data for Various
Dihapto-Coordinated Olefin Complexes of Pentaammineosmium(II)
reduction
δ (ppm)
CR (CH) Câ (CH
41.79
potential
compd
R-substituent
2
) Ep,a (V) E1/2 (V)
2
2
3
8
9
1
1
1
4
7
7
2
9
0
6
H
0.65
0.58
0.76
0.67
0.65
0.86
0.36
0.67
1.03
1.28
CH
C(CH
3
47.33
56.45
93.30
88.49
87.08
65.18
60.91
57.84
70.25
17.49 (d)
48.77
43.04
38.77
33.05
32.35
31.34
36.02
32.85
33.80
30.49
39.40
38.47
3
)
2
COCH
3
3
OCH
OH
2
CH
d
b
1
1
1
2
2
1
2
1
OOCCH
NHPh
3
NHCOCH
3
3
HNdC(OEt)(CH )
pyridine
b
PPh
S(CH
3
1.45
)
3 2
1.32
a
Recorded in acetonitrile-d
3
as a triflate salt, at 22 °C unless
b
c
otherwise noted. In acetone-d
TBAH, NHE. Compound 11 is isolated as the BPh
6
.
Recorded in acetonitrile/∼0.5 M
d
-
4
salt.
Figure 8. A comparison of reaction patterns for a vinyl ether complex
with and without alkylation at the R-carbon.
Figure 7. 13C NMR spectrum of the dihapto-coordinated isopropenyl
cation-pentaammineosmium 32 in neat triflic acid-d .
1
features that are most consistent with the assignment of 10 as
the Fischer carbene shown in Figure 3. Previously, we have
observed that protonation of methoxycarbene complexes of
pentaammineosmium results in formation of carbynes, and true
to form, protonation of the mixture of the vinyl ether 9 and
carbene 10 prepared from 3-butyn-1-ol (Vide supra) results in
the formation of carbyne complex 34 (via 10) along with the
isolated (Et2O and CH2Cl2). Judging from the integration of
1
the methyl signal in the H NMR spectrum and the H-C
1
3
coupling pattern of the methyl group in a proton-coupled
C
NMR spectrum of 33,19 the carbyne complex was recovered in
its fully protonated form. In contrast to the vinyl cation 32,
the carbyne complex 33 shows no H/D scrambling in a triflic
acid-d1 solution.
2
cyclic imidate 25 (via 9). Alternatively, protonation of the η -
dihydrofuran complex 5 in HOTf or DME (2 M LiOTf)
generates the corresponding carbyne complex 34, but attempts
to isolate 34 in analytically pure form were unsuccessful.
Structural assignments of all carbene and carbyne complexes
of pentaammineosmium(II) in this paper are made on the basis
of a comparison of spectral data with previously reported
As mentioned previously, when {Os(NH3)5}2 is generated
in the presence of 3-butyn-1-ol and methanol, a mixture of two
products is isolated in a 3:2 ratio (Figure 3). The minor
component 10 shows an overlap of the cis- and trans-ammine
proton resonances and a 13C resonance at 256.5 ppm, spectral
+
17
pentaamminesosmium carbene and carbyne complexes.
19) 13C-1H coupling constants of complex 33 are as follows: 1JCH )
The ruthenium analog 8 of the ethoxyethene complex 1
behaves quite differently from its congener in acidic methanol.
(
2
1
34.5 Hz and JCH ) 7.9 Hz.

5
678 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Chen and Harman
A methanolic solution of 8 containing acid (HOTf, 0.30 M)
was allowed to stand for 5 days, then the solution was added to
a mixture of CH2Cl2 and Et2O, and the precipitated salts were
1
13
isolated. According to H and C NMR spectra (CD3CN), the
product mixture contains starting material and a new compound
also containing ethoxyethene but shows no trans-ammine signal
1
in the H NMR. Incorporation of methanol was ruled out given
the absence of a detectable methyl signal. Over time the product
mixture slowly decomposes and free ethoxyethene is released.
Discussion
Features of Nucleophilic Substitution. Nucleophilic addi-
tion and substitution reactions of olefins bound to cationic
II 20
II 21
II 22
transition-metal complexes, particularly Pd , Pt , and Fe ,
have been extensively studied and in many cases sucessfully
applied to organic synthesis.2 The characteristic feature for
these systems is the ability of the transition metal to activate
the coordinated olefin toward nucleophilic addition and to
stabilize the resulting carbanion through a σ metal-alkyl bond
that can be further elaborated. In the present study, the transition
metal center is acting in a complimentary sense. Despite its
divalent character, the pentaammineosmium(II) system acts as
an electron donor through a substantial interaction with the olefin
π* orbital. In the case of a vinyl ether or vinyl ester complex,
for example, coordination by osmium(II) facilitates the loss of
the oxygen substituent through the stabilization of the resulting
vinyl cation. When the R-carbon contains an alkyl substituent
a
(
e.g., 32), this intermediate can be isolated.
Figure 9. Stereochemistry of nucleophilic substitution of a vinyl ether
or addition to an alkyne coordinated to pentammineosmium(II), and a
comparison of the intermediate vinyl cation species.
The fundamental difference in the vinyl ether substitution
reactions observed for the pentaammineosmium(II) system and
other cationic metal centers is that the substitution is electro-
phile-initiated. Whereas most nucleophilic substitutions of
cationic transition metal olefin complexes (e.g., Fe(II) and Pt-
data. This preference for addition to the vinyl cation trans to
the â-carbon alkyl group is also seen for the dihydrofuran
complex 5 where the kinetic isomer is 13b, the trans isomer of
II)) occur by addition-elimination processes,23 the osmium-
II) olefin system functions by an elimination-addition process.
2
(
(
the η -4-methoxy-3-buten-1-ol complex. Related to this is work
2
concerning the electrophilic addition of [Os(NH ) (2,3-η -(5-
3 5
2
+ 25
In the case of the acid-catalyzed isomerization and substitution
reaction of the ethoxypropene complexes 7a and 7b, a dissocia-
tive substitution mechanism would explain the following
experimental observations. Starting from a 1:1 equilibrated
mixture of 7a and 7b in acidic methanol, the trans substitution
product 12b is formed much earlier than is the cis form 12a.
Inspection of molecular models reveals that the approach of a
nucleophile (i.e., methanol) trans to the methyl substituent of
the â-carbon for a hypothetical vinyl cation should be favored
by steric arguments (Figure 9). When a 2:1 mixture of 7a and
methylfuran))] , where we have observed that, upon elec-
trophilic addition at C(4), the C(5)-O bond severs and methanol
adds to C(2). The stereochemistry of the initial product (-40
°C) is once again trans. A final example can be found in the
addition of methanol or water to the 2-butyne complex of
5
pentaammineosmium(II). Here, under acidic conditions, the
addition of the nucelophile to the bound alkyne initially gives
only substituted cis-2-butenes. In light of the present study,
the addition is thought to be initiated by protonation of the
alkyne ligand, resulting in a vinyl cation analogous to 32 (see
2
6
7
b is treated with an acid solution containing triphenylphos-
Figure 9). Subsequent addition of methanol or water trans
to the â-carbon substituent of the vinyl cation leads to the cis-
butene isomer. We note that, in the case of the enol, the
thermodynamically favored isomer is formed from cis addition
phine, where the nucleophile adds irreVersibly to the olefin, the
2
only product isolated is the trans isomer of [Os(NH3)5(η -1-
3+
propenyltriphenylphosphonium)] , a vinylphosphonium com-
plex analogous to 20.24 Further evidence comes from the
equilibrium ratio of 7a and 7b which is 1:1 in ethanol.
Assuming a dissociative mechanism where ktrans > kcis (Vide
supra) for loss of ethanol, the addition of ethanol to the vinyl
cation trans to the methyl group must be more facile than that
for the cis form in order to be consistent with the equilibrium
2
(
24) Characterization of [Os(NH3)5(η -1-propenyltriphenylphosphonium)]-
1
(
OTf)3. H NMR (acetonitrile-d3): δ 7.92-7.68 (m, 15 H, overlap of H-Ph),
4.68 (d, J ) 11.7 Hz, 2H, overlap of two olefinic protons), 4.42 (br s, 3H,
1
3
trans-NH3), 3.07 (br s, 12H, cis-NH3), 1.73 (s, 3H, CH3). C NMR
(
acetonitrile-d3): δ 135.89 (s, CH, p-C on Ph), 134.34 (d, JPC ) 9.7 Hz,
CH, o-C on Ph), 131.65 (d, JPC ) 12.2 Hz, CH, m-C on Ph), 123.12 (d, JPC
) 83.0 Hz, q, ipso-C on Ph), 46.81 (CH), 20.68 (d, J ) 72.0 Hz, CH),
PC
1
1
8.81 (CH3). H NMR (acetonitrile-d3, -40 °C): δ 7.92-7.68 (m, 15 H,
(20) (a) Heck, R. F. Palladium Reagents in Organic Synthesis; Aca-
overlap of H-Ph), 4.71 (t, J ) 10.7 Hz, 1H, CH), 4.56 (m, 1H, CH), 4.38
(br s, 3H, trans-NH3), 3.00 (br s, 12H, cis-NH3), 1.68 (d, J ) 5.6 Hz, 3H,
CH3). Stereochemical assignment is made on the basis of the large vicinal
coupling constant (JHH ) 10.7 Hz).
demic: New York, 1985. (b) Hegedus, L. S. ComprehensiVe Organic
Synthesis; Pergamon: Oxford, U.K., 1992; Vol. 4, Chapter 3.
(21) (a) Panunzi, A.; DeRenzi, A.; Palumbo, R.; Paiaro, G. J. Am. Chem.
Soc. 1969, 91, 3879. (b) Panunzi, A.; DeRenzi, A.; Paiaro, G. J. Am. Chem.
Soc. 1970, 92, 3488.
(25) Chen, H.; Liu, R.; Harman, W. D. Manuscript in preparation.
(26) Protonation of the 2-butyne complex in absence of a nucleophile
generates a vinyl cation analogous to 32. Chen, H.; Harman, W. D.
(22) (a) Lennon, P.; Madhavarao, M.; Rosan, A. M.; Rosenblum, M. J.
2
Organomet. Chem. 1976, 108, 93. (b) Lennon, P.; Rosan, A. M.; Rosenblum,
M. J. Am. Chem. Soc. 1977, 99, 8426.
Unpublished results. Characterization of [Os(NH3)5(η -C(CH3)CH(CH3))]-
1
(OTf)3. H NMR (acetonitrile-d3/HOTf, ratio 5:1): δ 4.61 (br s, 3H, trans-
(
23) (a) Chang, T. C. T.; Rosenblum, M.; Samuels, S. B. J. Am. Chem.
Soc. 1980, 102, 5930. (b) Marsi, M.; Rosenblum, M. J. Am. Chem. Soc.
984, 106, 7264.
NH3), 4.29 (br s, 12H, cis-NH3), 3.98 (m, 1H, CH), 2.36 (s, 3H, CH3),
13
1.84 (d, J ) 6.8 Hz, 3H, CH3). C NMR (HOTf, with CD2Cl2 as internal
1
reference): δ 299.40 (q), 44.02 (CH), 37.47 (CH3), 10.92 (CH3).

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5679
of the nucleophile (i.e., water). In the above cases, the
stereochemistry of the kinetic products was self-consistent but
was independent of the stereochemistry of the reactants. The
pentaammineosmium carbene complexes.17 On these grounds
it would seem reasonable to describe 32 as a form of metallo-
2
cyclopropene (η -vinyl) similar to the rhenium and molybdenum
2
2
isolation (triflate salt) and characterization of 32 as an η -vinyl
systems. Although the η -vinyl complexes of molybdenum-
cation species, in the context of the above observations, provides
supporting evidence that the substitution process is dissociative
in nature, especially when one considers the broad range of mild
nucleophiles (silyl enol ethers, pyridine, dimethyl sulfide,
phosphines, nitriles), which add on similar time scales. Finally,
when equal amounts of the methoxyethene (2) and methoxy-
propene (3) complexes were dissolved in CD3OD and treated
with acid (0.019 M HOTf, 22 °C), the more substituted propene
complex underwent methoxide substitution at a rate that was
(0), rhenium(I), and osmium(II) are likely to be structurally as
well as spectroscopically similar, their chemical behavior is very
different. The reaction between the weak acid C6F5SH and [Mo-
2
5
{η -C(R)CHPh}{P(OMe)3}2(η -C5H5)] reveals that the vinyl
ligand in this species behaves chemically as a vinyl anion; i.e.,
31
the R-carbon behaves like an alkylidine. In contrast, the vinyl
ligand of pentaammineosmium complex 32 functions as a vinyl
cation; i.e., the R-carbon acts like a Fischer carbene (Figure
3
2
8).
>
100-fold that of the ethene analog. Were these substitution
Formation of Osmium Carbynes. Over the last decade,
several η -vinyl complexes of molybdenum and tungsten have
2
reactions primarily associative, the relative rate of the less
substituted olefin 2 would be expected to be significantly faster
than that of the more hindered 3. This result too is readily
explained by a dissociative mechanism, where the extra methyl
group on 3 stabilizes the vinyl cation intermediate.
been reported to undergo a 1,2 migration of hydrogen or
3
3
trimethylsilyl to form carbyne complexes. A similar trans-
formation is invoked for the protonation of the vinyl ether
2
complex 1 by HOTf (Figure 9) to form carbyne 33. An η -
2
3+
The formation of the η -imidate salts 22-25 (Figure 5) from
vinyl cation intermediate analogous to [Os(NH3)5(C2H5)] (32)
acetonitrile and various vinyl ether complexes provides an
interesting example of vinyl substitution followed by nitrilium
electrophilic addition that represents a net insertion of the nitrile
into the vinyl ether C-O linkage. True to theme, the insertion
reaction is thought to be initiated by the proton-assisted loss of
alcohol to generate the corresponding vinyl cation. Addition
of acetonitrile to the vinyl cation activates the nitrile carbon
toward electrophilic addition by an alcohol, completing the
formation of the vinyl imidate salt. This reaction is conceptually
similar to the Pinner reaction or its modification by Borch that
forms imidates from nitrilium salts and alcohols.27 In order to
verify that the acetonitrilium ion itself was not an active
participant in this reaction, methylnitrilium triflate was combined
with the vinyl ether 1 in absence of any alcohol, but under
otherwise identical reaction conditions. Over a similar reaction
period, no reaction was observed.
is expected to be the direct product of protonation, and this
species proceeds through a 1,2-hydrogen shift to give the
2
carbyne 33. The isomerization of the η -vinyl cation [Os(NH3)5-
3
+
3+
(C2H3)] to [Os(NH3)5(tCCH3)] can occur in principle by
either an intra- or intermolecular process. The observation that
compound 1 dissolved in neat DOTf results in a carbyne without
any detectable incorporation of deuterium clearly indicates that
the intramolecular mechanism is the only one operative under
the stated reaction conditions. All attempts to deuterate the
methyl group of the carbyne 33 or directly generate a vinylidine
species by treating 33 with base have been unsuccessful.
In the case of the vinyl cation 32, conversion to a carbyne
would involve a 1,2-alkyl shift, a process expected to have a
much higher kinetic barrier. In addition, the methyl group is
able to stabilize the electrophilic R-carbon more effectively than
a hydrogen through hyperconjugation; thus, carbyne complexes
are not generated from vinyl ethers in cases where the R-carbon
is alkylated. However, in contrast to the carbyne, the methyl
group of the vinyl cation 32 is readily deuterated. Presumably
Of the known examples of transition metal complexes bearing
vinyl ligands, most have the vinyl group attached through a
1
2
single σ bond (η ). Few η -vinyl complexes are known to date,
2
34
and these have been limited to earlier transition metals (e.g.,
this reaction occurs via an η -allene intermediate (Figure 9),
2
8
2
Mo, W, or Re), these species having been investigated for
their possible role in insertion, oligomerization, and cocycliza-
a species similar to that serving as the precursor to the η -vinyl
species [ReCl{η -C(CH2Ph)CH2}(dppe)2](BF4).
2
29
2
tion reactions of alkynes. Rearrangements of η -vinyl species
Conclusions. Coordination of the electron-rich pentaammi-
neosmium(II) moiety to a vinyl ether dramatically alters the
structural and chemical nature of the ligand. These species
readily undergo a vinylic substitution reaction, passing through
a dihapto-coordinated vinyl cation intermediate. Using this
method, a wide range of dihapto-coordinated pentaammine-
osmium(II) olefin complexes were synthesized from vinyl ether
precursors. When the R-carbon of the vinyl ether is alkylated,
the vinyl cation intermediate is stabilized to the point that it
may be isolated as its triflate salt and characterized in acetonitrile
or triflic acid solution. When the R-carbon bears only a
3
to carbyne, carbene, allene, and η -allyl complexes have also
been demonstrated.28 However, surprisingly little is known
about their reactivity toward nucleophiles and electrophiles.
2
2
Among the few well-studied η -vinyl complexes, trans-[ReCl{η -
2
9
2
C(CH2Ph)CH2}(dppe)2][BF4]
P(OMe)3}2(η -C5H5)] are useful comparisons for the osmium
species 32. Like these η -vinyl complexes of rhenium(III) and
molybdenum(II), a resonance far downfield (299.8 ppm) is
observed in the 13C NMR spectrum for the osmium(IV) species
and [Mo{η -C(R)CHPh}-
5
30
{
2
3
2 (DOTf, 22 °C), characteristic of a carbon-metal multiple
bond. The methylene resonance for 32 (29.2 ppm) is also in
good agreement with the corresponding values for the Re and
Mo systems. Finally, the chemical shifts of the cis- and trans-
ammines are relatively close to each other, similar to those of
(
31) Green, M.; Norman, N. C.; Orpen, A. G. J. Am. Chem. Soc. 1981,
03, 1267.
32) Prior to publication of this paper a study by Green et al. appeared
demonstrating hydride addition to a rhenium η2
1
(
-vinyl cation complex.
See: Carfagna, C.; Carr, N.; Deeth, R. J.; Dossett, S. J.; Green, M.; Mahon,
M. F.; Vaughan, C. J. Chem. Soc., Dalton. Trans. 1996, 415.
(33) (a) For a review of the formation of carbyne complexes involving
R,â-migration of hydrogen in a vinyl ligand, see: Mayr, A.; Hoffmeister,
H. AdV. Organomet. Chem. 1991, 32, 251. (b) Bottrill, M.; Green, M. J.
Am. Chem. Soc. 1977, 99, 5795. (c) Allen, S. R.; Beevor, R. G.; Green,
M.; Orpen, A. G.; Paddick, K. E.; Williams, I. D. J. Chem. Soc., Dalton
Trans. 1987, 591. (d) Atagi, L. M.; Mayer, J. M. Polyhedron 1995, 14 (1),
113.
(
27) (a) Neilson, D. G. In The Chemistry of Amidines and Imidates; Patai,
S., Ed.; J. Wiley & Sons: New York, 1975; Chapter 9, pp 389-412. (b)
Borch, R. F. J. Org. Chem. 1969, 34, 627.
(28) (a) Green, M. J. Organomet. Chem. 1986, 300, 93 and references
within. (b) Pombeiro, A. J. L. J. Organomet. Chem. 1988, 358, 273 and
references within.
(
29) Pombeiro, A. J. L.; Hughes, D. L.; Richards, R. L.; Silvestre, J.;
Hoffmann, R. J. Chem. Soc., Chem. Commun. 1986, 1125.
30) Allen, S. R.; Beevor, R. G.; Green, M.; Norman, N. C.; Orpen, A.
G.; William, I. D. J. Chem. Soc., Dalton Trans. 1985, 103, 1267.
2
(
(34) Our attempts to generate an η -allene from 33 resulted in intractable
mixtures.

5
680 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Chen and Harman
hydrogen, a 1,2-hydrogen shift occurs in absence of nucleo-
philes, resulting in a pentaammineosmium(II) carbyne. Thus,
for nucleophilic substitution a reaction pattern common to sp
carbons is imparted on vinylic systems through coordination to
an electron-rich transition metal.
solution was added to a methanol (6.10 g) suspension of ethoxyethene
(
5.22 g, 72.4 mmol) and Zn/Hg (9.4 g). The slurry was stirred (22
°C) for 15 min and then filtered into a stirred mixture of Et O (600
mL) and CH Cl (200 mL), giving a light yellow precipitate. The
precipitate was collected by filtration, washed with CH Cl and Et O,
and dried in Vacuo. Yield: 1.07 g (1.66 mmol, 91%). H NMR
acetonitrile-d ): δ 5.70 (dd, J ) 6.3, 4.8 Hz, 1H, CH), 4.08 (br s, 3H,
trans-NH ), 3.69 (m, 2H, CH ), 3.06 (dd, J ) 6.3, 2.4 Hz, 1H, CH ),
.00 (br s, 12H, cis-NH ), 2.85 (dd, J ) 4.8, 2.4 Hz, 1H, CH ), 1.13 (t,
): δ 93.30 (CH), 71.00
CN, TBAH, 100 mV/s):
OsF : C, 11.16;
3
2
2
2
2
2
2
1
(
3
Experimental Section
3
2
2
3
3
2
General Procedures. Infrared spectra were recorded on a Mattson
13
1
13
J ) 6.9 Hz, 3H, CH
CH ), 33.05 (CH ), 15.57 (CH
1/2 ) 0.67 V (NHE). Anal. Calcd for C
3
). C NMR (acetonitrile-d
3
Cygnus 100 FTIR spectrometer. Routine H and C NMR spectra
were recorded on a General Electric QE-300 or GN-300 spectrometer
(
E
2
2
3
). CV (CH
3
1
13
6
H
23
O
7 5
N
S
2
6
at 20-23 °C unless otherwise noted ( H and C NMR spectra were
obtained at 300 and 75 MHz, respectively). Carbon multiplicities, if
provided, are supported by DEPT and/or HETCOR data. Chemical
shifts are reported in parts per million and are referenced to residual
H, 3.59; N, 10.85. Found: C, 10.90; H, 3.51; N, 10.50.
2
[Os(NH )
3 5
(2,3-η -methoxyethene)](OTf)
2
(2). A solution of 1 (55.7
mg, 0.0863 mmol) in methanol (398 mg) was added to a methanolic
solution of HOTf (3.2 mg, 0.0216 mmol). After 1 h, the reaction
proton-containing solvent (δ(acetone-d
5
) ) 2.04; δ(acetonitrile-d ) )
2
1
.93; δ(methanol-d ) ) 3.30). Electrochemical experiments were
3
mixture was added to Et
that was filtered, washed with Et
Yield: 39.3 mg (0.0622 mmol, 72%). H NMR (acetonitrile-d
5.69 (dd, J ) 6.3, 5.1 Hz, 1H, CH), 4.07 (br s, 3H, trans-NH ), 3.52
2
O (50 mL), giving a light yellow precipitate
O and CH Cl , and dried in Vacuo.
): δ
performed under nitrogen using a PAR Model 362 potentiostat driven
by a PAR Model 175 universal progammer. Cyclic voltammograms
were recorded (Kipp & Zonen BD90 XY recorder) in a standard three-
2
2
2
1
3
3
3
5
(s, 3H, CH ), 3.09 (dd, J ) 6.3, 2.7 Hz, 1H, CH ), 3.00 (br s, 12H,
electrode cell from +1.8 to -1.8 V with a glassy carbon electrode.
3
2
13
All potentials are reported vs NHE and, unless otherwise noted, were
cis-NH
3
), 2.84 (dd, J ) 5.1, 2.7 Hz, 1H, CH
2
). C NMR (acetonitrile-
). CV (CH CN, TBAH,
determined in acetonitrile (∼0.5 M TBAH) using ferrocene (E1/2
)
d
3
): δ 95.26 (CH), 63.18 (CH
3
), 33.40 (CH
2
3
+
0.55 V) or colbaltocenium hexafluorophosphate (E1/2 ) -0.78 V) in
100 mV/s): E1/2 ) 0.67 V (NHE). Anal. Calcd for C
OsF : C, 9.51; H, 3.35; N, 11.09. Found: C, 9.92; H, 3.42; N, 10.99.
[Os(NH
propene (4.15 g, 57.6 mmol) was dissolved in DME (3.76 g) and cooled
(OTf)](OTf) (827 mg, 1.14 mmol)
5 21 7 5 2
H O N S -
situ as a calibration standard. The peak-to-peak separation (Ep,a - Ep,c
)
6
2
was between 80 and 100 mV for all reversible couples unless otherwise
noted. This work was carried out under a nitrogen atmosphere in a
Vacuum Atmospheres Co. glovebox, separate boxes being used for
aqueous and nonaqueous reactions. When necessary, the complexes
were purified by (a) redissolving in acetone or acetonitrile and
reprecipitation or (b) ion-exchange chromatography using Sephadex
SP C-25 resin with aqueous NaCl as the mobile phase. Salts purified
by ionic-exchange chromatography were precipitated as their tetraphen-
3
)
5
(2,3-η -2-methoxypropene)](OTf)
2
(3). 2-Methoxy-
to -20 °C. A solution of [Os(NH
)
3 5
2
in DMAc (896 mg) was added dropwise to the chilled ligand solution
0
with Mg (2.56 g, 0.107 mmol) present. The slurry was stirred for 30
min (22 °C) and was filtered into a mixture of Et
CH Cl (400 mL). The resulting tan precipitate was filtered, washed
with Et O, and dried in Vacuo. Yield: 599 mg (0.927 mmol, 81%). 3
may also be prepared by reducing [Os(NH (OTf)](OTf) with Zn/Hg
in methanol. 1H NMR (acetonitrile-d
): δ 4.07 (br s, 3H, trans-NH ),
3.48 (s, 3H, OCH ), 3.26 (d, J ) 2.1 Hz, 1H, H-C3), 3.03 (br s, 12H,
cis-NH ), 2.91 (d, J ) 2.1 Hz, 1H, H-C3), 1.49 (s, 3H, CH
NMR (acetonitrile-d ): δ 94.95 (q), 59.29 (OCH ), 35.63 (CH ), 18.62
(CH ). CV (CH
Calcd for C
2
O (400 mL) and
2
2
2
ylborate salts by adding an excess of aqueous NaBPh
4
. Elemental
)
3 5
2
analyses were obtained in house on a Perkin-Elmer PE-2400 Series II
CHN analyzer.
Solvents. All solvents were deoxygenated by purging with nitrogen
for at least 15 min; deuterated solvents were deoxygenated either by
repeated freeze-pump-thaw cycles or by vacuum distillation. All
distillations were performed under nitrogen. Methylene chloride was
3
3
3
1
3
3
3
).
C
3
3
2
3
3
CN, TBAH, 100 mV/s): E1/2 ) 0.61 V (NHE). Anal.
H
6 23
O
7
N
5
S
2
OsF
6
: C, 11.16; H, 3.59; N, 10.85. Found: C,
refluxed over P
over Mg(OMe)
distilled. Acetonitrile and propionitrile were refluxed over CaH
2
O
5
for at least 8 h and distilled. Methanol was refluxed
10.94; H, 3.42; N, 10.99.
2
0
2
prepared in situ from magnesium activated by I
2
and
and
3 5
[Os(NH ) (2,3-η -6H-4,5-dihydropyran)](OTf)
2
(4). Mg (0.67 g,
2
3 5 2
28 mmol) was added to a solution of [Os(NH ) (OTf)](OTf) (332 mg,
distilled. Aldrich anhydrous grade DMAc and DME were used without
further purification, except that they were deoxygenated prior to use.
0.460 mmol), 3,4-2H-dihydropyran (0.913 g, 10.6 mmol), DMAc (1.31
g), and DME (2.36 g), and the slurry was stirred for 2 h. The reaction
Reagents. [Os(NH
)
3 5
(OTf)](OTf)
2
was synthesized as described by
mixture was filtered into Et
washed with Et O, and dried in Vacuo. Yield: 216.4 mg (0.329 mmol,
72%). H NMR (acetonitrile-d ): δ 6.06 (d, J ) 6.0 Hz, 1H, H-C2),
4.03 (br s, 3H, trans-NH ), 3.69 (dt, J ) 6.6, 2.4 Hz, 1H, H-C6), 3.55
(td, J ) 10.8, 2.4 Hz, 1H, H-C6), 3.35 (t, J ) 6.0 Hz, 1H, H-C3), 3.02
(br s, 12H, cis-NH ), 2.80 (m, 1H, H-C4), 1.57 (m, 1H, H-C5), 1.51
(m, 1H, H-C4), 1.13 (m, 1H, H-C5). C NMR (acetonitrile-d
89.92 (C2), 66.10 (C6), 40.0 (C3), 24.95 (C5), 23.46 (C4). CV (CH
2
O (300 mL), and the product filtered,
3
6
Lay et al. but can also be purchased from Aldrich. Magnesium
powder (Aldrich, 50 mesh) was activated by treating with iodine in
DME under nitrogen, stirring for 1 h, filtering, and washing with DMAc,
acetone, and diethyl ether. Dihydrofuran and 2-methoxypropene were
purified by distillation from CaH
used as received except that they were deoxygenated prior to use.
2
1
3
3
2
. All the other liquid reagents were
3
13
3
): δ
N-Methylacetonitrilium Triflate. A modification of the reported
3
-
37
CN, TBAH, 100 mV/s): E1/2 ) 0.49 V (NHE). Anal. Calcd for
procedure was used: In a drybox, methyl triflate (837 mg, 5.10 mmol)
was dissolved in acetonitrile (518 mg), and the reaction mixture was
heated in an oil bath at 65-75 °C for 30 min. The reaction mixture
was cooled to room temperature and then added dropwise to the chilled
C
7
H
23
O
7
N
5
S
2
OsF
3.64; N, 10.31.
[Os(NH
6
: C, 12.79; H, 3.53; N, 10.65. Found: C, 13.10; H,
2
3
)
5
(2,3-η -4,5-dihydrofuran)](OTf)
2
2
(5). The synthesis of
CH
washed with benzene. The yellow product was purified by repeated
dissolving in acetonitrile and precipitating with CH Cl to give a pale
yellow powder. Yield: 680 mg (3.32 mmol, 66%).
Complexes. The synthesis and characterization of the furan complex
2
Cl
2
, giving a yellow precipitate. The precipitate was filtered and
5 by direct hydrogenation of [Os(NH
full characterization have been reported. In an alternative method,
[Os(NH (OTf)](OTf) (1.04 g, 1.44 mmol) was dissolved in methanol
3
)
5
(2,3-η -furan)](OTf)
2
and its
6a
2
2
)
3 5
2
(6.83 g), and the solution was added dropwise to a slurry of
dihydrofuran (5.44 g, 77.6 mmol), Zn/Hg (11.4 g), and methanol (6.12
g). After being stirred for 9 min, the reaction mixture was filtered.
2
6a
[
Os(NH
Os(NH
1.32 g, 1.83 mmol) was dissolved in methanol (6.92 g), and this
3
)
5
(η -furan)](OTf)
2
(6) have been previously reported.
2
2 2
The filtrate was concentrated and then added to a mixture of CH Cl
[
3
)
5
(η -ethoxyethene)](OTf) (1). [Os(NH (OTf)](OTf)
2
3
)
5
2
2
(500 mL) and Et O (550 mL), producing a light orange precipitate that
(
was collected, washed with CH
Yield: 846 mg (1.31 mmol, 91%). H NMR (acetonitrile-d
2
Cl
2
1
and Et
2
O, and dried in Vacuo.
): δ 6.11
(
35) Bard, A. J.; Faulkner, L. R. Electrochemical Methods; John Wiley
Sons: New York, 1980.
36) (a) Lay, P. A.; Magnuson, R. H.; Taube, H. Inorg. Chem. 1989, 28,
3
&
(
(
d, J ) 3.9 Hz, 1H, H-C2), 4.02 (dt, J ) 9.6, 4.2 Hz, 1H, H-C5), 3.99
br s, 3H, trans-NH ), 3.48 (t, J ) 4.2 Hz, 1H, H-C3), 3.02 (br s, 12H,
), 2.97 (q, J ) 9.0 Hz, 1H, H-C5), 2.75-2.62 (m, 1H, H-C4),
(
3
3
2
001. (b) Lay, P. A.; Magnuson, R. H.; Taube, H. Inorg. Synth. 1986, 24,
cis-NH
1.81 (ddd, J ) 13.5, 8.4, 4.5 Hz, 1H, H-C4). C NMR (acetonitrile-
): δ 95.43 (C2), 69.39 (C5), 37.64 (C3), 30.05 (C4). CV (CH CN,
3
69.
13
(37) Booth, B. L.; Jibodu, K. O.; Proenca, M. F. J. Chem. Soc., Chem.
Commun. 1980, 1151.
d
3
3

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5681
TBAH, 100 mV/s):
E
1/2 ) 0.63 V (NHE). Anal. Calcd for
J ) 4.0 Hz, 1H, OH), 3.70 (br s, 3H, trans-NH
2.9 Hz, 1H, H-C2), 2.78 (br s, 12H, cis-NH ), 2.76 (dd, J ) 5.2, 2.9
Hz, 1H, H-C2). 13C NMR (acetonitrile-d
): δ 165.08 (m, JB-C ) 50.6
Hz, Ph), 136.69 (Ph), 126.64 (Ph), 122.8 (Ph), 88.49 (C1), 32.35 (C2).
3
), 2.99 (dd, J ) 6.9,
C
3
6
H
21
O
7
N
5
S
2
OsF
.37; N, 11.22.
Os(NH
6
: C, 11.20; H, 3.29; N, 10.88. Found: C, 11.52; H,
3
3
2
(6).6a 1H NMR (acetonitrile-d
[
3
)
5
(2,3-η -furan)](OTf)
2
3
): δ
1
7
.25 (d, J ) 3.3 Hz, 1H, H-C2), 6.90 (d, J ) 2.7 Hz, 1H, H-C5), 6.05
Anal. Calcd for C50
Found: C, 61.86; H, 6.42; N, 7.70.
H
59ON
5
B
2
2 2
Os‚ / H O: C, 62.11; H, 6.26; N, 7.24.
(
3
d
t, J ) 2.4 Hz, 1H, H-C3), 4.85 (t, J ) 2.7 Hz, 1H, H-C4), 4.02 (br s,
1
3
2
H, trans-NH
3
), 2.85 (br s, 12H, cis-NH
3
). C NMR (acetonitrile-
[Os(NH
3
)
5
(cis-η -1-methoxypropene)](OTf)
2 3 5
(12a) and [Os(NH ) -
2
3
): δ 142.69 (C5), 111.96 (C4), 98.64 (C2), 48.96 (C3).
(trans-η -1-methoxypropene)](OTf) (12b). A solution of triflic acid
2
2
[
Os(NH
3 5
)
(cis-η -1-ethoxypropene)](OTf)
2
(7a) and [Os(NH
)
3 5
-
(10.4 mg, 0.0693 mmol) in methanol was added to a solution of a 2:1
mixture of complexes 7a and 7b (67.2 mg, 0.102 mmol). After 4 h,
2
(trans-η -1-ethoxypropene)](OTf) (7b). [Os(NH
2
3 5
)
(OTf)](OTf) (426
2
mg, 0.589 mmol) was dissolved in methanol (4.10 g) and added to a
methanol (1.55 g) suspension of 1-ethoxypropene (2.75 g, 31.9 mmol)
and Zn/Hg (3.4 g). The slurry was stirred for 15 min and then filtered
the solution was added to Et
precipitate that was filtered, washed with Et
2
O (60 mL), producing a light yellow
2
O and CH Cl , and dried
2
2
in Vacuo. Yield: 42.2 mg (0.0653 mmol, 64%). The solid appeared
1
into a stirred mixture of Et
a light yellow precipitate. The precipitate was collected by filtration,
washed with CH Cl and Et
0.544 mmol, 92%). The solid appeared by H NMR to be in a 2:1
2
O (250 mL) and CH
2
Cl
2
(50 mL), giving
by H NMR to be a mixture of two isomers 12a and 12b in a 1:1 ratio.
6 23 5 7 2 6
Anal. Calcd for C H N O S OsF : C, 11.16; H, 3.59; N, 10.85.
2
2
2
O and dried in Vacuo. Yield: 359 mg
Found: C, 11.58; H, 3.84; N, 10.70.
1
1
(
12a. H NMR (acetonitrile-d
(br s, 3H, trans-NH ), 3.54 (s, 3H, OCH
s, 12H, cis-NH ), 1.16 (d, J ) 6.9 Hz, CH
): δ 94.41 (CH), 60.92 (OCH ), 38.34 (CH), 10.70 (CH3).
): δ 5.65 (d, J ) 5.7 Hz, 1H), 3.99
), 3.54 (s, 3H, CH ), 3.13 (m, 1H, CH), 2.97 (br
), 1.27 (t, J ) 6.7 Hz, 3H, CH
): δ 97.00 (CH), 63.07 (CH ), 39.22 (CH), 14.24 (CH
(cis-3,4-η -4-methoxy-3-buten-1-ol)](OTf)
3
): δ 5.48 (d, J ) 5.4 Hz, 1H), 4.00
ratio. CV (CH
3
CN, TBAH, 100 mV/s): E1/2 ) 0.66 V (NHE). Anal.
OsF : C, 12.75 H, 3.82; N, 10.62. Found: C,
2.56; H, 3.91; N, 10.60.
a (Major Isomer). 1H NMR (acetonitrile-d
Hz, 1H), 3.99 (br s, 3H, trans-NH ), 3.72 (m, 2H, CH
CH), 2.97 (br s, 12H, cis-NH ), 1.20 (d, J ) 6.9 Hz, 3H, CH
). C NMR (acetonitrile-d ): δ 92.84 (CH), 69.10
), 38.55 (CH), 15.65 (CH ), 10.94 (CH ).
b (Minor Isomer). H NMR (acetonitrile-d
3
3
), 3.45 (m, 1H, CH), 2.98 (br
13
Calcd for C
7
H N O
25 5 7
S
2
6
3
3
). C NMR (acetonitrile-
1
d
3
3
1
7
3
): δ 5.53 (d, J ) 5.2
), 3.44 (m, 1H,
), 1.16 (t,
12b. H NMR (acetonitrile-d
(br s, 3H, trans-NH
s, 12H, cis-NH
3
3
2
3
3
13
3
3
3
3
). C NMR (acetonitrile-
).
(13a) and
(13b).
13
J ) 6.7 Hz, 3H, CH
CH
3
3
d
3
3
3
2
(
2
3
3
[Os(NH
3
)
5
2
1
2
7
3
): δ 5.64 (d, J ) 6.0
), 3.70 (q, J ) 7.2 Hz, 2H, CH ),
), 1.25 (d, J ) 6.0 Hz, 3H,
[Os(NH (trans-3,4-η -4-methoxy-3-buten-1-ol)](OTf)
3
)
5
2
A
Hz, 1H), 3.99 (br s, 3H, trans-NH
3
2
solution of triflic acid (8.2 mg, 0.055 mmol) in methanol (200 mg)
was added to a solution of 5 (121 mg, 0.188 mmol) in methanol (611
mg). After 9 h, N,N-diisopropylethylamine (12.9 mg, 0.100 mmol)
was added to the reaction mixture. After 5 min, the reaction mixture
3
.12 (m, 1H, CH), 2.97 (br s, 12H, cis-NH
3
1
3
CH
3
), 1.16 (t, J ) 6.7 Hz, 3H, CH
3
). C NMR (acetonitrile-d
), 14.06 (CH
(8). A solution of ethoxy-
ethene (1.64 g, 22.7 mmol) was prepared in acetone (1.18 g) and cooled
to -20 °C. [Ru(NH (OTf)](OTf) (827 mg, 0.352 mmol) was
3
): δ
9
5.26 (CH), 70.81 (CH
2
), 39.75 (CH), 15.66 (CH
3
3
).
2
[
Ru(NH )
3 5
(η -ethoxyethene)](OTf)
2
was added to Et
filtered, washed with Et
89.1 mg. The solid appeared by H NMR to be a mixture of two
2
O (120 mL), producing a tan precipitate that was
2
O and CH Cl , and dried in Vacuo. Yield:
2
2
1
3
)
5
2
dissolved in acetone (1.10 g), and the solution added dropwise into
the chilled ligand solution along with Zn/Hg (8.5 g). The slurry was
3
isomers and starting material in a 6:3:1 ratio. CV (CH CN, TBAH,
100 mV/s): Ep,a ) 0.78 V (NHE).
stirred for 20 min (22 °C), and then filtered into a mixture of Et
300 mL) and CH Cl (200 mL). The white precipitate was filtered,
washed with Et O and CH Cl , and dried in Vacuo. Yield: 135 mg
0.243 mmol, 69%). H NMR (acetonitrile-d ): δ 5.89 (dd, J ) 8.7,
), 3.57 (br s, 3H, trans-NH ), 3.08
), 2.84 (dd, J ) 5.1, 2.2 Hz, 1H, CH ),
). C NMR
), 15.32
2
O
13a (Minor Isomer). 1H NMR (acetonitrile-d
3
): δ 5.44 (d, J )
3
), 3.80 (m, 2H, H-C1),
(
2
2
5.4 Hz, 1H, H-C4), 4.03 (br s, 3 H, trans-NH
3.56 (s, 3H, OCH ), 3.06 (m, 1H, overlap with cis-NH
(br s, 12H, cis-NH
2
2
2
3
3
, H-C3), 3.06
1
13
(
3
3
), 2.03 (m, 1H, H-C2), 1.38 (m, 1H, H-C2).
C
5
.1 Hz, 1H, CH), 3.81 (m, 2H, CH
2
3
NMR (acetonitrile-d
3
): δ 93.58 (C4), 62.73 (C1), 60.72 (OCH
3
), 38.73
(
1
dd, J ) 8.7, 2.2 Hz, 1H, CH
2
2
(C3), 29.23 (C2).
1
3
13b (Major Isomer). 1H NMR (acetonitrile-d
.82 (br s, 12H, cis-NH
3
), 1.20 (t, J ) 6.9 Hz, 3H, CH
3
3
): δ 5.70 (d, J )
(
acetonitrile-d
3
): δ 112.65 (CH), 70.73 (OCH
2
), 49.85 (CH
2
6.0 Hz, 1H, H-C4), 3.74 (m, 2H, H-C1), 4.07 (br s, 3H, trans-NH
3.53 (s, 3H, OCH ), 3.41 (m, 1H, H-C3), 3.07 (br s, 12 H, cis-NH
1.42 (m, 1H, H-C2), 1.19 (m, 1H, H-C2). C NMR (acetonitrile-d
δ 95.77 (C4), 62.19 (OCH ), 62.19 (C1), 40.13 (C3), 32.42 (C2).
3
),
),
3
):
(
CH ). CV (CH
3
3
CN, TBAH, 100 mV/s): Ep,a ) 1.14 V (NHE). Anal.
RuF : C, 12.95; H, 4.17; N, 12.59. Found: C
3.30; H 4.33; N 12.73.
3
3
13
Calcd for C
1
6
25
H N
5
O
7
S
2
6
3
2
[
Os(NH
NH (2-oxacyclopentylidene)](OTf)
107 mg, 0.148 mmol) was dissolved in methanol (1.45 g), and then
-butyn-1-ol (413 mg, 5.89 mmol) and Zn/Hg (797 mg) were added.
After stirring (5 min), the slurry was filtered into CH Cl (200 mL),
producing an orange yellow precipitate that was collected, washed with
CH Cl and Et O, and dried in Vacuo. Yield: 70 mg. The solid
appeared by H NMR to be a mixture of 9 and 10 in a 3:2 ratio.
3 5
) (3,4-η -3-methoxy-3-buten-1-ol)](OTf)
2
(9) and [Os-
When the reaction is run at -40 °C, and 3 days later worked up
under the same conditions, the recovered product is exclusively 13b
(
(
3
)
3 5
2
(10). [Os(NH
3 5
) (OTf)](OTf)
2
7 25 8 5 2 6
in a yield of 62%. Anal. Calcd for C H O N S OsF : C, 12.45; H,
3.73; N, 10.37. Found: C, 12.47; H, 3.77; N, 10.25.
2
2
2
[Os(NH ) (η -carbomethoxyethene)](OTf) (14). The ethoxy-
3
5
2
ethene complex 1 (116 mg, 0.179 mmol) was dissolved in acetic acid
(1.09 g) at 22°C. After 50 min, this solution was added to a mixture
of Et O (60 mL) and CH Cl (60 mL), producing a pale yellow
2
2
2
1
2
2
2
1
9
.
H NMR (acetonitrile-d
m, 2H, H-C1), 3.45 (s, 3H, OCH
.20 (br s, 12H, cis-NH ), 2.86 (d, J ) 2.7 Hz, 1H, H-C4), 2.76 (q, J
15 Hz, 1H, H-C2), 1.40 (ddd, J ) 15.6, 9.6, 4.5 Hz, H-C2), OH(?).
3
): δ 4.04 (br s, 3H, trans-NH
3
), 3.89
precipitate. This solid was filtered, washed with Et
and dried in Vacuo. Yield: 109 mg (0.165 mmol, 92%). H NMR
(acetonitrile-d ): δ 6.92 (t, J ) 5.9 Hz, 1H, CH), 4.16 (br s, 3H, trans-
NH ), 3.39 (dd, J ) 5.9, 3.3Hz, 1H, CH ), 3.19 (dd, J ) 5.9, 3.3 Hz,
1H, CH ), 3.11 (br s, 12H, cis-NH ), 1.99 (s, 3H, CH
(acetonitrile-d ): δ 174.07 (q), 87.08 (CH), 31.34 (CH ), 21.23 (CH
Anal. Calcd for C OsF : C, 10.93; H, 3.21; N, 10.62.
Found: C, 10.79; H, 3.23; N, 10.56.
2 2 2
O and CH Cl ,
1
(
3
3
), 3.23 (d, J ) 2.7 Hz, 1H, H-C4),
3
3
)
3
2
13
13
C NMR (acetonitrile-d
C4), 38.0 (C2).
0. 1H NMR (acetonitrile-d
.18 (br s, 15H, trans- and cis-NH
3
): δ 91.3 (C3), 59.6 (OCH
3
), 58.0 (C1), 38.0
2
3
3
). C NMR
).
(
3
2
3
1
3
): δ 4.39 (t, J ) 7.5 Hz, 2H, H-C3),
), 2.04 (quintet, J ) 7.5 Hz, 2H,
6
H
21
O
8
N
5
S
2
6
3
3
1
3
2
H-C4), 1.49 (t, J ) 7.5 Hz, 2H, H-C4). C NMR (acetonitrile-d
56.5 (OsdC), 77.9 (C3), 53.0 (C5), 24.6 (C4).
3
): δ
[Os(NH )
3 5
2
(η -2-carbomethoxypropene)](OTf) (15). The 2-meth-
2
oxypropene complex 3 (46.6 mg, 0.0722 mmol) was dissolved in acetic
acid (1.35 g, 22 °C), and after 1 h, the solution was added to a mixture
2
[
Os(NH
55.5 mg, 0.0860 mmol) in H
HOTf (8.6 mg, 0.0573 mmol) in H
saturated aqueous solution of NaBPh was added to the reaction mixture,
giving a white precipitate. The solid was collected, washed with H O,
and dried in Vacuo. Yield: 65.2 mg (0.0674 mmol, 78%). H NMR
acetonitrile-d ): δ 7.29 (br s, 16H, H-Ph), 7.01 (t, J ) 7.2 Hz, 16H,
H-Ph), 6.86 (t, J ) 7.2 Hz, 8H, H-Ph), 5.93 (m, 1H, H-C1), 3.83 (d,
3
)
5
(η -hydroxyethene)](BPh
O (654 mg) was added a solution of
O (110 mg). After 10 min, a
4 2
) (11). To a solution of 1
(
2
of Et
precipitate. This solid was filtered, washed with Et
and dried in Vacuo. Yield: 42.2 mg (0.0626 mmol, 88%). H NMR
(acetonitrile-d ): δ 4.11 (br s, 3H, trans-NH ), 3.42 (d, J ) 5.7 Hz, 1
H, CH ), 3.30 (d, J ) 5.7 Hz, 1H, CH ), 3.10 (br s, 12H, cis-NH ),
1.91 (s, 3H, CH ): δ
172.11 (q), 90.84 (q), 38.08 (CH ). CV
2
O (35 mL) and CH
2
Cl
2
(35 mL), producing a pale yellow
2
2
O and CH Cl
2
2
,
1
4
2
3
3
1
2
2
1
3
3
(
3
3
), 1.56 (s, 3H, CH
3
). C NMR (acetonitrile-d
3
2 3 3
), 21.46 (CH ), 21.19 (CH

5
682 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Chen and Harman
3 3
), 5.08 (m, overlap with trans-NH , 1H, H-C1), 4.84
(CH
3
CN, TBAH, 100 mV/s): E1/2 ) 0.86 V (NHE). Anal. Calcd for
OsF : C, 12.48; H, 3.44; N, 10.40. Found: C, 12.38; H,
3H, trans-NH
(m, 1H, H-C2), 4.73 (m, 1H, H-C2), 3.71 (br s, 12H, cis-NH
NMR (acetone-d ): δ 135.57 (s, CH, p-C on Ph), 134.68 (d, JPC ) 7.4
Hz, CH, o-C on Ph), 131.44 (d, JPC ) 11.1 Hz, CH, m-C on Ph), 123.09
(d, JPC ) 79.0 Hz, q, ipso-C on Ph), 39.40 (CH ), 17.49 (d, JPC ) 69.5
Hz, CH). Anal. Calcd for C23 OsF : C, 27.30; H, 3.29; N,
1
3
C
7
H
23
O N
8 5
S
2
6
3
).
C
3
.35; N, 10.49.
6
2
[
Os(NH
3
)
5
3
(η -vinyldimethylsulfonium)](OTf) (16). A solution of
complex 1 (116 mg, 0.180 mmol) in acetonitrile (500 mg) was
combined with methyl sulfide (93.2 mg), followed by TMSOTf (69.5
mg, 0.263 mmol). After 10 min, the yellow reaction mixture was added
2
H
33
O
9
N
5
S
3
9
6.92. Found: C, 27.30; H, 3.67; N, 7.44.
2
to Et
CH Cl
NMR (acetonitrile-d
2
O, giving a precipitate that was filtered, washed with Et
, and dried in Vacuo. Yield: 140 mg (0.173 mmol, 96%). H
): δ 4.73 (t, J ) 7.8 Hz, 1H, H-C1), 4.51 (br s,
), 4.15 (dd, J ) 7.8, 3.9 Hz, 1H, H-C2), 3.94 (dd, J )
.8, 3.9 Hz, H-C2), 3.40 (br s, 12H, cis-NH ), 3.06 (s, 3H, CH ), 2.92
): δ 48.77 (C1), 38.47 (C2),
). Anal. Calcd for C OsF : C,
2
O and
[Os(NH )
3 5
(η -isopropenyltriphenylphosphonium)](OTf)
3
(21). A
1
2
2
solution of complex 3 (40.8 mg, 0.0632 mmol) in acetonitrile (400
mg) was treated with triphenylphosphine (33.0 mg, 0.125 mmol),
3
3
7
H, trans-NH
3
followed by BF
was added to Et
washed with Et
3
2
‚OEt (16.0 mg, 0.112 mmol). After 1 h, the reaction
3
3
2
O (70 mL), giving a yellow precipitate that was filtered,
1
3
(s, 3H, CH
3
). C NMR (acetonitrile-d
), 27.99 (CH
3
2
O, and dried in Vacuo. Yield: 44.2 mg (0.0443 mmol,
3
3.81 (CH
3
3
7
H
24
O
9
N
5
S
4
9
70%). 1H NMR (acetone-d
6
): δ 8.07 (dd, J ) 10.8, 8.7 Hz, 6H, H-Ph),
1
0.36; H, 2.98; N, 8.63. Found: C, 10.72; H, 3.12; N, 8.62.
7.91 (dd, J ) 7.5, 6.9 Hz, 3H, H-Ph), 7.80 (m, 6H, H-Ph), 5.36 (dd, J
) 17.4, 2.7 Hz, 1H, H-C2), 5.06 (br s, 3H, trans-NH ), 4.88 (dd, J )
15.9, 2.7 Hz, 1H, H-C2), 3.76 (br s, 12H, cis-NH ), 1.96 (d, J ) 14.7
): δ 135.61 (s, CH, p-C on Ph),
2
[
Os(NH
3
)
5
(η -1-(N-phenylamino)ethene)](OTf)
2
(17). Complex 1
3
(
34.4 mg, 0.0533 mmol) was dissolved in a mixture of acetic acid (400
mg) and aniline (200 mg). After 3 h, the reaction mixture was
precipitated in a mixture of Et O (35 mL) and hexane (35 mL), giving
a tan precipitate that was filtered, washed with Et O and CH Cl , and
dried in Vacuo. Yield: 30.5 mg (0.0440 mmol, 83%). H NMR
acetonitrile-d ): δ 7.16 (dd, J ) 8.1, 7.2 Hz, 2H, H-Ph), 6.87 (d, J )
.1 Hz, 2H, H-Ph), 6.67 (t, J ) 7.2 Hz, 1H, H-Ph), 5.30 (dd, J ) 8.2,
.7 Hz, 1H, H-C1), 4.03 (br s, 3H, trans-NH ), 3.16 (dd, J ) 6.7, 2.0
3
13
3 6
Hz, 3H, CH ). C NMR (acetone-d
135.37 (d, JPC ) 8.9 Hz, CH, o-C on Ph), 131.47 (d, JPC ) 12.1 Hz,
CH, m-C on Ph), 121.77 (d, JPC ) 79.5 Hz, q, ipso-C on Ph), 53.26
2
2
2
1
2
(CH
2
), 25.35 (d, JPC ) 12.5 Hz, CH
3
), 23.75 (d, JPC ) 54.1 Hz, q).
(22). A
2
(
8
6
3
[Os(NH )
3 5
(ethyl η -N-vinylacetimidate)‚(HOTf)](OTf)
2
solution of 1 (53.4 mg, 0.0827 mmol) in acetonitrile (661 mg) was
added to a solution of HOTf (29.0 mg, 0.166 mmol) in acetonitrile
(120 mg). After 10 min, the yellow reaction mixture was added to a
3
Hz, 1H, H-C2), 3.13 (dd, J ) 8.2, 2.0 Hz, 1H, H-C2), 3.06 (br s, 12H,
1
cis-NH
H-Ph), 6.90 (d, J ) 8.1 Hz, 2H, H-Ph), 6.57 (t, J ) 7.5 Hz, 1H, H-Ph),
.57 (dd, J ) 7.8, 6.9 Hz, 1H, H-C1), 4.69 (br s, 3H, trans-NH ), 3.68
br s, 12H, cis-NH ), 3.38 (dd, J ) 6.9, 1.8 Hz, 1H, H-C2), 3.36 (dd,
J ) 7.8, 1.8 Hz, 1H, H-C2). C NMR (acetone-d
29.66 (Ph), 117.58 (Ph), 113.93 (Ph), 65.18 (C1), 36.02 (C2). The
3
). H NMR (acetone-d
6
): δ 7.08 (dd, J ) 8.1, 7.5 Hz, 2H,
mixture of Et
precipitate that was filtered, washed with CH
in Vacuo. Yield: 62.0 mg (0.0740 mmol, 90%). H NMR (acetonitrile-
): δ 9.57 (br s, 1 H, H-N), 5.90 (dd, J ) 7.2, 6.9 Hz, 1H, CH), 4.30
(br s, 3H, trans-NH ), 4.57 (q, J ) 6.9 Hz, 2H, CH ), 3.87 (dd, J )
7.2, 3.6 Hz, 1H, CH ), 3.50 (dd, J ) 6.9, 3.6 Hz, 1H, CH ), 3.21 (br
s, 12 H, cis-NH ), 2.38 (s, 3H, CH ), 1.49 (t, J ) 6.9 Hz, 3H, CH ).
C NMR (acetonitrile-d ): δ 176.17 (q), 71.98 (OCH ), 57.84 (CH),
33.80 (CH ), 18.97 (CH ), 15.57 (CH ). Anal. Calcd for
2
O (60 mL) and CH
2
Cl
2
(30 mL), giving a yellow
2
Cl and Et O, and dried
2
1
2
5
(
3
3
d
3
1
3
6
): δ 151.02 (Ph),
3
2
1
2
2
crude product was redissolved in acetonitrile and treated with 2 equiv
of N,N-diisopropylethylamine. After 5 min, the solution was repre-
3
3
3
13
3
2
cipitated to give a clean product. Anal. Calcd for C10
OsF : C, 17.34; H, 3.49; N, 12.13. Found: C, 17.23; H, 3.76; N,
1.74.
Os(NH
(52.7 mg, 0.0816 mmol) was dissolved in a mixture of acetic acid
H
24
O
6
N S
6 2
-
2
3
3
6
C
9
H
27
N
6
O S
10 3
9
OsF : C, 12.92; H, 3.25; N, 10.04. Found: C, 12.62;
1
H, 3.28; N, 10.13.
2
2
[
3 5
)
(η -2-(N-phenylamino)propene)](OTf)
2
(18). Complex
[Os(NH
(OTf)
(2.30 g) was treated with HOTf (134 mg, 0.893 mmol). After 10 min,
the reaction mixture was added to CH Cl (100 mL), giving an orange
yellow precipitate that was filtered, washed with CH Cl and Et O,
and dried in Vacuo. Yield: 99.2 mg (0.117 mmol, 86%). H NMR
(acetonitrile-d ): δ 8.79 (br s, 1H, H-N), 5.72 (td, J ) 12.0, 0.9 Hz,
1H, H-C8), 5.62 (d, J ) 6.9 Hz, 1H, H-C4), 4.60 (dd, J ) 12.0, 4.5
Hz, 1H, H-C8), 4.30 (br s, 3H, trans-NH ), 3.69 (ddd, J ) 12.0, 6.9,
2.7 Hz, 1H, H-C5), 3.25 (br s, 12H, cis-NH ), 2.36 (s, 3H, CH ), 2.31
(overlap with CH , 1H, H-C7), 1.88 (m, 1H, H-C6), 1.79 (m, 1H, H-C7),
1.41 (m, 1H, H-C6). 13C NMR (acetonitrile-d
): δ 177.70 (C2), 74.57
(C8), 58.70 (C4), 46.14 (C5), 28.37 (C7), 23.25 (C6), 23.30 (CH ).
Anal. Calcd for C10 OsF : C, 14.15; H, 3.21; N, 9.90.
3
)
5
(4,5-η -7,8-dihydro-2-methyl-6H-1,3-oxazocine)‚HOTf)]-
3
2
(23). A solution of 4 (89.4 mg, 0.136 mmol) in acetonitrile
(
727 mg) and aniline (345 mg, 22 °C). After 2 h, the reaction mixture
was added to a mixture of Et O (45 mL) and hexane (15 mL), giving
a light yellow precipitate. The solid was filtered, washed with Et
and CH Cl , and dried in Vacuo. Yield: 49.3 mg (0.0698 mmol, 86%).
H NMR (acetonitrile-d ): δ 7.16 (dd, J ) 7.5, 7.2 Hz, 2H, H-Ph),
.98 (d, J ) 7.5 Hz, 2H, H-Ph), 6.67 (t, J ) 7.2 Hz, 1H, H-Ph), 4.20
2
2
2
2
O
2
2
2
1
2
2
1
3
3
6
(br s, 3H, trans-NH
3
), 3.59 (d, J ) 1.2 Hz, 2H, CH
2
), 3.18 (br s, 12H,
3
13
cis-NH
3
), 1.45 (s, 3H, CH
3
). C NMR (acetonitrile-d ): δ 150.09 (Ph),
3
3
3
1
29.90 (Ph), 118.9 (Ph), 115.5 (Ph), 64.70 (C1), 47.98 (C2), 22.06
CH ). The product was redissolved in acetone, treated with N,N-
diisopropylethylamine, and then reprecipitated in the mixture of Et
and hexane. Yield: 70%. Anal. Calcd for C11 OsF : C,
8.70; H, 3.71; N, 11.89. Found: C, 18.50; H, 3.78; N, 11.99.
3
(
3
3
2
O
3
H O
26 6
N
6
S
2
6
H
27
N
6
O S
10 3
9
1
Found: C 13.90; H 2.83; N 9.09.
2
2
[
Os(NH
3
)
5
(η -N-vinylpyridinium)](OTf)
3
(19). A solution of 16
[Os(NH
(OTf)
(660 mg) was treated with HOTf (47.5 mg, 0.317 mmol). After 10
min, the reaction mixture was added to CH Cl (100 mL), giving an
orange yellow precipitate that was filtered, washed with CH Cl and
Et O, and dried in Vacuo. Yield of yellow powder: 94.0 mg (0.113
mmol, 86%). H NMR (acetonitrile-d
(d, J ) 6.9 Hz, H-C4), 5.03 (m, 1H, H-C7), 4.97 (m, 1H, H-C7), 4.32
(br s, 3H, trans-NH ), 4.09 (q, J ) 7.5 Hz, H-C5), 3.25 (br s, 12H,
cis-NH ), 2.58 (m, 1H, H-C6), 2.34 (s, 3H, CH ), 1.94 (m, 1H, H-C6).
C NMR (acetonitrile-d ): δ 173.64 (C2), 78.32 (C7), 58.97 (C4),
45.25 (C5), 31.57 (C6), 23.40 (CH ). Anal. Calcd for C
OsF : C, 12.95; H, 3.02; N, 10.07. Found: C, 13.08; H, 3.12; N,
9.83.
[Os(NH
(HOTf)](OTf)
3
)
5
(4,5-η -6,7-dihydro-2-methyl-6H-1,3-oxazepine)‚(HOTf)]-
(
(
35.3 mg, 0.0435 mmol) in acetonitrile (1 g) was treated with pyridine
15 mg, 0.19 mmol). After 5 min, the reaction solution was added to
2
(24). A solution of 5 (84.1 mg, 0.131mmol) in acetonitrile
a mixture of Et
precipitate that was filtered, washed with Et
in Vacuo. Yield: 31.0 mg (0.0374 mmol, 86%). H NMR (acetonitrile-
): δ 8.71 (d, J ) 5.8 Hz, 2H, o-H on py), 8.46 (t, J ) 6.9 Hz, 1H,
p-H on py), 7.94 (t, J ) 7.0 Hz, 2H, m-H on py), 6.56 (t, J ) 7.4 Hz,
H, CH), 4.94 (dd, J ) 7.4, 5.4 Hz, 1H, CH ), 4.48 (br s, 3H, trans-
NH ), 4.04 (dd, J ) 7.4, 5.4 Hz, 1H, CH ), 3.26 (br s, 12H, cis-NH ).
C NMR (acetonitrile-d ): δ 144.24 (CH), 140.90 (CH), 130.49 (CH),
0.25 (CH), 30.49 (CH ). Anal. Calcd for C10 OsF : C,
2
O (40 mL) and CH
2
Cl
2
(10 mL), giving a peach
2
2
2
O and CH Cl , and dried
2
2
2
2
1
2
1
d
3
3
): δ 9.59 (br s, 1H, H-N), 5.57
1
2
3
3
2
3
3
3
13
13
3
3
7
1
2
H
23
O
9
N
6
S
3
9
3
9 25 6 10 3
H N O S -
4.49; H, 2.80; N, 10.14. Found: C, 14.21; H, 2.83; N, 9.98.
9
2
[
Os(NH
3
)
5
(η -vinyltriphenylphosphonium)](OTf)
3
(20). A solu-
tion of complex 1 (41.5 mg, 0.0643 mmol) in acetonitrile (500 mg)
was treated with triphenylphosphine (43.1 mg, 0.164 mmol), followed
3
)
5
(6-methyl-3,4-dihydro-5-oxa-2-pyridone methide)‚
(25) and [(NH OstCCH CH CH OH](OTf) (34).
2
)
3 5
2
2
2
3
by BF
solution was added to Et
washed with Et O, and dried in Vacuo. Yield: 53.4 mg (0.0528 mmol,
2%). H NMR (acetone-d ): δ 8.15 (dd, J ) 11.7, 7.5 Hz, 6H, H-Ph),
.88 (dd, J ) 7.5, 6.6 Hz, 3H, H-Ph), 7.77 (m, 6H, H-Ph), 5.08 (br s,
3
‚OEt
2
(18.4 mg, 0.130 mmol). After 2 days, the orange reaction
An orange solution of the mixture of 9 and 10 (53.6 mg) in acetonitrile
(853 mg) was treated with HOTf (22.2 mg, 0.148 mmol) in acetonitrile
(210 mg), giving a yellow solution. After 5 min, the reaction mixture
2
O, giving an orange solid that was filtered,
2
1
8
7
6
was added to a mixture of Et
2
O (35 mL) and CH
Cl
2 2
(35 mL), producing
O and CH Cl
a yellow precipitate that was filtered, washed with Et
2
2
2
,

2
Nucleophilic Substitution of η -Olefin Complexes
J. Am. Chem. Soc., Vol. 118, No. 24, 1996 5683
1
and dried in Vacuo. Yield: 54.3 mg. The solid appeared by H NMR
to be a mixture of two products, 25 and 34, with the same ratio as that
0.0960 mmol) in acetonitrile (0.76 g) and a solution of TMSOTf (9.6
mg, 0.0363 mmol) in acetonitrile (0.78 g) were prepared. After cooling,
these solutions were mixed and allowed to stand at -40 °C. After 10
of the mixture of starting complexes 9 and 10.
1
2
5. H NMR (acetonitrile-d
3
): δ 8.58 (br s, 1H, H-N), 4.91 (dt, J
h, the solution was added to a mixture of Et
(35 mL), giving a light yellow precipitate that was filtered, washed
with Et O and CH Cl , and dried in Vacuo. Yield: 41.7 mg (0.0634
mmol, 87%). 1H NMR (acetonitrile-d
): δ 4.12 (br s, 3H, trans-NH ),
3.51 (m, 1H, H-C4), 3.08 (m, overlap with cis-NH , 2H, H-C5), 3.02
(br s, 12H, cis-NH ), 2.54 (dd, J ) 15.6, 3.0 Hz, 1H, H-C3), 2.26 (dd,
J ) 15.6, 9.3 Hz, 1H, H-C3), 2.17 (s, 3H, CH
): δ 211.21 (C2), 47.12 (C3), 44.95 (C4), 42.20 (C5), 27.98 (C1).
Anal. Calcd for C OsF : C, 12.78; H, 3.53; N, 10.65.
2 2 2
O (35 mL) and CH Cl
)
11.1, 3.9 Hz, 1H), 4.59 (td, J ) 11.1, 2.7 Hz, 1H), 4.37 (br s, 3H,
trans-NH ), 3.97 (d, J ) 3.0 Hz, 1H), 3.60 (d, J ) 3.0 Hz, 1H), 3.33
br s, 12H, cis-NH ), 2.30 (s, 3H, CH ), 2.26 (ddd, J ) 14.1, 11.1, 3.9
Hz, 1H), 1.85 (overlap with solvent peak, 1H). C NMR (acetonitrile-
3
2
2
2
(
3
3
3
3
13
3
d
2
3
): δ 175.16 (q), 72.65 (CH
1.01 (CH ).
4. H NMR (acetonitrile-d
J ) 4.8 Hz, 2H), 3.34 (br s, 3H, trans-NH
2
), 60.65 (q), 37.67 (CH
2
), 29.25 (CH
2
),
3
13
3
3
). C NMR (acetonitrile-
1
3
3
): δ 4.73 (br s, 12H, cis-NH
), 2.62 (t, J ) 6.0 Hz, 2H),
): δ 302.18 (OstC), 61.52
3
), 3.67 (t,
d
3
3
7
H
23
O
7
N
5
S
2
6
1
3
2
.10 (m, 2H). C NMR (acetonitrile-d
CH ), 53.99 (CH ), 26.39 (CH ).
Os(NH (η -N-vinylacetamide)‚(HOTf)](OTf)
(η -N-vinylacetiamide](OTf) (27). A solution of complex 1
76.6 mg, 0.119 mmol) in acetonitile (726 mg) was treated with H
42.9 mg, 2.38 mmol), and then HOTf (34.1 mg, 0.227 mmol), giving
3
Found: C, 12.63; H, 3.38; N, 10.27.
(
2
2
2
2
[
Os(NH
3
)
5
(methyl 3,4-η -2,2-dimethyl-3-butenoate)](OTf)
2
(31).
2
[
)
3 5
2
(26) and [Os-
A solution of 14 (48.7 mg, 0.0738 mmol) and methyl trimethylsilyl
ketene dimethyl acetal (17.5 mg, 0.100 mmol) in acetonitrile (0.89 g)
was prepared, and cooled to -40 °C. A solution of TMSOTf (10.7
mg, 0.0404 mmol) in acetonitrile (0.78 g) was also cooled to -40 °C,
and then added to the reaction mixture. After 12 h, the solution was
treated with pyridine (17 mg, 0.215 mmol) and then directly added to
2
(
(
(
NH
3
)
5
2
2
O
a bright yellow solution. After 15 min, the solution was added to Et
with stirring, giving a yellow precipitate that was filtered, washed with
Et O and CH Cl
2
O
2
2
2
, and dried in Vacuo. Yield of orange yellow solid
a mixture of Et
After being stirred for 10 min, a light orange precipitate formed that
was filtered, washed with Et O and CH Cl , and dried in Vacuo.
Yield: 43.1 mg (0.0614 mmol, 83%). H NMR (acetonitrile-d ): δ
), 3.57 (dd, J ) 10.2,
.0 Hz, 1H, H-C3), 3.42 (dd, J ) 10.2, 1.5 Hz, 1H, H-C4), 3.10 (br s,
2H, cis-NH ), 2.85 (dd, J ) 9.0, 1.5 Hz, 1H, H-C4), 1.46 (s, 3H,
), 1.07 (s, 3H, CH
6.45 (C3), 52.82 (OCH
CH ). Anal. Calcd for C
2 2 2
O (30 mL), CH Cl (20 mL), and hexane (20 mL).
2
6: 76.4 mg (0.0944 mmol).
An orange solution of 26 (50.0 mg) in acetone (500 mg) was treated
with DIEA (20 mg, 0.15 mmol). After 1 min, the solution was
precipitated in a mixture of Et O (25 mL) and CH Cl (25 mL), giving
a light yellow precipitate, 27. Yield: 41.5 mg (0.0630 mmol, 81%
from 1).
2
2
2
1
3
2
2
2
4
9
1
CH
5
3 3
.06 (br s, 3H, trans-NH ), 3.66 (s, 3H, OCH
3
2
6. 1H NMR (acetonitrile-d
3
): δ 13.22 (br s, 1H, OH), 8.42 (br d,
J ) 7.5 Hz, 1H, H-N), 5.93 (q, J ) 7.5 Hz, 1 H, CH), 4.18 (br s, 3H,
trans-NH ), 3.61 (dd, J ) 7.5, 2.7 Hz, 1H, CH ), 3.28 (dd, J ) 7.5,
.7 Hz, 1H, CH ), 3.19 (br s, 12H, cis-NH ), 2.16 (s, 3H, CH
NMR (acetonitrile-d ): δ 175.24 (q), 56.24 (CH), 33.19 (CH ), 21.47
13
3
3
). C NMR (acetonitrile-d
), 47.30 (C2), 38.77 (C4), 32.10 (CH
OsF : C, 15.41; H, 3.88; N, 9.98.
3
): δ 180.85 (C1),
3
3
), 25.21
3
2
(
9 27
H
O
N S
8 5 2
3
6
13
2
2
3
3
).
C
Found: C, 15.49; H, 3.80; N, 9.63.
3
2
2
[
Os(NH
3
)
5
(η -C
3
H
5
)](OTf)
3
(32). A solution of 3 (107.1, 0.166
3
(CH ).
mmol) in acetonitrile (0.90 g) was cooled to -40 °C and treated with
a solution of HOTf (78.9 mg, 0.526 mmol). After 8 min, the peach
2
7. 1H NMR (acetonitrile-d
.94 (q, J ) 7.5 Hz, 1 H, CH), 4.03 (br s, 3H, trans-NH
), 3.05 (dd, J ) 7.2, 2.7 Hz, 1H, CH
3
): δ 6.95 (br d, J ) 7.2 Hz, 1H, H-N),
), 3.25 (dd,
), 3.19
). C NMR (acetonitrile-d ): δ
), 23.16 (CH ). CV (CH CN,
1/2 ) 0.67 V (NHE). Anal. Calcd for
: C, 10.94; H, 3.37; N, 12.76. Found: C, 11.34; H,
5
3
solution was added to a mixture of Et
producing a dark peach precipitate that was filtered, washed with Et
and CH Cl , and dried in Vacuo. Yield: 100 mg (0.131 mmol, 79%).
H NMR (acetonitrile-d /triflic acid, ratio = 5:1): δ 4.35 (br s, 3H,
trans-NH ), 4.11 (br s, 12H, cis-NH ), 3.12 (br s, 2H, CH ), 2.37 (br
s, 3H, CH ). C NMR (DOTf, with CD Cl as internal reference): δ
99.85 (q), 37.24 (CH ); C NMR (acetonitrile-d /triflic
), 27.60 (CH ) (quartenary carbon not
2 2 2
O (80 mL) and CH Cl (20 mL),
J ) 7.2, 2.7 Hz, 1H, CH
br s, 12H, cis-NH ), 1.86 (s, 3H, CH
73.90 (q), 60.91 (CH), 32.85 (CH
TBAH, 100 mV/s):
OsF
.26; N, 12.55.
2
2
2
O
1
3
(
1
3
3
3
2
2
2
3
3
1
3
E
3
3
2
C
3
H O N
6 22 7 6
S
2
6
13
3
2
2
13
2
3
), 29.19 (CH
2
3
2
[
Os(NH
3
)
5
(η -ethylene)](OTf)
2
(28).14 A solution of complex 1
81.2 mg, 0.126 mmol) in acetonitrile (721 mg) was treated with
triethylsilane (24.1 mg, 0.184 mmol), followed by TMS(OTf) (11.9
mg, 0.0450 mmol). After 1 h, the yellow reaction mixture was added
acid, ratio = 5:1): δ 36.41 (CH
identified).
3
2
(
[
Os(NH
mmol) was ground into a fine powder, and dissolved in HOTf (1.77
g). After 20 min, the solution was added to Et O (100 mL), producing
a fine light brown precipitate that was filtered, washed with Et O and
CH Cl , and dried in Vacuo. The crude product (116 mg) was dissolved
in acetone (1.5 g), and then reprecipitated with a mixture of Et O (80
mL) and CH Cl (40 mL). The precipitate was collected, washed with
Et O and CH Cl , and dried in Vacuo. Yield of tan solid: 78.6 mg
0.104 mmol, 83%). H NMR (acetone-d
NH ), 3.78 (br s, 3H, trans-NH ), 2.10 (s, 3H, CH
(acetonitrile-d ): δ 4.58 (br s, 12H, cis-NH ), 3.12 (br s, 3H, trans-
NH ), 2.09 (s, 3H, CH ). C NMR (acetone-d ): δ 296.07 (q), 41.71
CH ). CV (CH CN, TBAH, 100 mV/s): Ep,c ) -1.25 V (NHE). Anal.
Calcd for C OsF : C, 8.01; H, 2.42; N, 9.34. Found: C,
.75; H, 2.54; N, 8.89.
3 5 3 3
) (tCCH )](OTf) (33). Complex 1 (81.1 mg, 0.126
to Et
with Et
mmol, 92%). H NMR (acetonitrile-d
.01 (s, 4H, ethylene), 2.95 (br s, 12H, cis-NH
nitrile-d ): δ 41.79. CV (CH CN, TBAH, 100 mV/s): E1/2 ) 0.65 V
NHE). The complex was purified by ion-exchange chromatography
and isolated as its tetraphenylborate trihydrate salt. Anal. Calcd for
Os‚3H O: C, 60.30; H, 6.58; N, 7.44. Found: C, 60.68;
H, 6.63; N, 7.12.
2
O (100 mL), giving a white precipitate that was filtered, washed
O and CH Cl , and dried in Vacuo. Yield: 69.7 mg, (0.116
): δ 4.11 (br s, 3H, trans-NH ),
). C NMR (aceto-
2
2
2
2
1
2
3
3
1
3
2
2
3
3
2
3
3
2
2
(
2
2
2
1
(
6
): δ 5.32 (br s, 12H, cis-
C H
50 59
N
5
B
2
2
1
3
3
3
). H NMR
2
(29).15 A solution of 3 (55.7 mg,
2
3
3
[
Os(NH
.0863 mmol) in acetonitrile (567 mg) was treated with triethylsilane
20.7 mg, 0.178 mmol), followed by TMS(OTf) (7.3 mg, 0.0276 mmol).
After 30 min, the reaction mixture was added to Et O (80 mL), giving
a white precipitate that was filtered, washed with Et O and CH Cl
and dried in Vacuo. Yield: 48.9 mg (0.0794 mmol, 92%). H NMR
O): δ 4.22 (br s, 3H, trans-NH ), 3.25 (m, 1H, CH), 3.14 (br s,
), 2.86 (d, J ) 7.2 Hz, 1H, CH ), 2.83 (d, J ) 5.1 Hz,
). C NMR (acetonitrile-d ): δ 47.33 (CH),
). CV (CH CN, TBAH, 100 mV/s): E1/2
.58 V (NHE). Anal. Calcd for C OsF : C, 9.76; H, 3.43;
3 5
)
(η -propene)](OTf)
13
3
3
6
0
(
(
3
3
H
5 18
O
9
N
5
S
3
9
2
8
2
2
2
,
1
(D
2
3
Acknowledgment. We gratefully acknowledge Professor M.
1
1
4
0
2H, cis-NH
3
2
G. Finn and Mr. M. L. Spera for their helpful suggestions, and
the Camille and Henry Dreyfus Foundation, the National Science
Foundation (NSF Young Investigator program), the Alfred. P.
Sloan Foundation, and Colonial Metals Inc. (Elkton, MD) for
their generous support of this work.
13
2
H, CH ), 1.23 (d, 3H, CH
3
3
2
3.04 (CH ), 15.88 (CH
3
3
)
5
H
21
O
6
5
N S
2
6
N, 11.34. Found: C, 9.74; H, 3.25; N, 11.56.
2
[Os(NH )
3 5
2
(4,5-η -4-penten-2-one)](OTf) (30). A solution of 14
(48.2 mg, 0.0730 mmol) and 2-[(trimethylsilyl)oxy]propene (12.5 mg,
JA960389J