Comparative reactivity of triruthenium and triosmium μ3-η2-Imidoyls. 2. Reactions with alkynes

Article abstract of DOI:10.1021/om9610915

The reactions of Ru₃(CO)₉(μ₃-η²-CH ₃C=NCH₂CH₃)(μ-H) (1), M₃(CO)₉(μ₃-η²-C=N(CH ₂)₃)(μ-H) (M = Ru (2), M = Os (3)) with the alkynes RC≡CR (R = CH₃, C₆H₅, CO₂Me) have been studied. The ruthenium complexes 1 and 2 react with 2-butyne at 70 °C to give two very different trimetallic alkyne derivatives: Ru₃(CO)₇(μ-η²:η⁴-C ₄(CH₃)₄)(μ-η²-CH ₃C=NCH₂CH₃)-(η¹-COC(CH ₃)C(H)CH₃ (5) and Ru₃(CO)₈(μ₃-η²-C=N(CH ₂)₃)(μ-η²-CH₃C(H)=CCH ₃) (6). The osmium imidoyl 3 does not react with 2-butyne even at elevated temperatures. However, the reaction of Os₃(CO)₉(μ-η²-C=N(CH₂) ₃)(μ-H)(CH₃CN) (7b), synthesized from Os₃(CO)₁₀-(μ-η²-C=N(CH₂) ₃)(μ-H) (7a), with 2-butyne yields the analog of 6, Os₃(CO)₈(μ₃-η²-C=N(CH ₂)³)(μ-η²-RC(H)=CR) (R = CH₃ (10), R = C₆H₅ (11)) on thermolysis of the initially formed nonacarbonyl precursors (8 and 9 for R = CH₃), which are a mixture of isomers. Direct reaction of 7a with diphenylacetylene at 100 °C gives somewhat lower yields of 11. The reaction of 7b with dimethylacetylenedicarboxylate or the direct reaction of 3 with this alkyne yields the nonacarbonyl derivative Os₃(CO)₉(μ-η²-C=N(CH₂) ₃)(μ₃-η³-CH₃O ₂CC=C(H)CO₂CH₃) (12). Direct reaction of 7a with a 2.5 molar excess trimethylamine N-oxide at room temperature yields the alkyne-imidoyl-coupled product Os₃(CO)₈(μ-η⁶-CH ₃C(H)=C(CH₃)C-(CH₃)=C(CH ₃)C=N(CH₂)₃) (13). The solid state structures of 5, 11, 12, and 13 are reported. A comparative study of the electrochemical properties of 5 and 1 is also reported.

Full text of DOI:10.1021/om9610915

2674
Organometallics 1997, 16, 2674-2681
Com p a r a tive Rea ctivity of Tr ir u th en iu m a n d Tr iosm iu m
µ3-η2-Im id oyls. 2. Rea ction s w ith Alk yn es
Shariff E. Kabir and Edward Rosenberg*
Department of Chemistry, The University of Montana, Missoula, Montana 59812
Luciano Milone, Roberto Gobetto, Domenico Osella, and Mauro Ravera
Dipartimento di Chimica IFM, Universita` di Torino, 10125 Torino, Italy
Timothy McPhillips, Michael W. Day, Douglas Carlot, Sharad Hajela,
Erich Wolf, and Kenneth Hardcastle
Department of Chemistry, California State University, Northridge, California 91330
Received December 23, 1996X
The reactions of Ru3(CO)9(µ3-η2-CH3CdNCH2CH3)(µ-H) (1), M3(CO)9(µ3-η2-CdN(CH2)3)(µ-
H) (M ) Ru (2), M ) Os (3)) with the alkynes RCtCR (R ) CH3, C6H5, CO2Me) have been
studied. The ruthenium complexes 1 and 2 react with 2-butyne at 70 °C to give two very
different trimetallic alkyne derivatives: Ru3(CO)7(µ-η2:η4-C4(CH3)4)(µ-η2-CH3CdNCH2CH3)-
(η1-COC(CH3)C(H)CH3) (5) and Ru3(CO)8(µ3-η2-CdN(CH2)3)(µ-η2-CH3C(H)dCCH3) (6). The
osmium imidoyl 3 does not react with 2-butyne even at elevated temperatures. However,
the reaction of Os3(CO)9(µ-η2-CdN(CH2)3)(µ-H)(CH3CN) (7b), synthesized from Os3(CO)10-
(µ-η2-CdN(CH2)3)(µ-H) (7a ), with 2-butyne yields the analog of 6, Os3(CO)8(µ3-η2-CdN(CH2)3)-
(µ-η2-RC(H)dCR) (R ) CH3 (10), R ) C6H5 (11)) on thermolysis of the initially formed
nonacarbonyl precursors (8 and 9 for R ) CH3), which are a mixture of isomers. Direct
reaction of 7a with diphenylacetylene at 100 °C gives somewhat lower yields of 11. The
reaction of 7b with dimethylacetylenedicarboxylate or the direct reaction of 3 with this alkyne
yields the nonacarbonyl derivative Os3(CO)9(µ-η2-CdN(CH2)3)(µ3-η3-CH3O2CCdC(H)CO2CH3)
(12). Direct reaction of 7a with a 2.5 molar excess trimethylamine N-oxide at room
temperature yields the alkyne-imidoyl-coupled product Os3(CO)8(µ-η6-CH3C(H)dC(CH3)C-
(CH3)dC(CH3)CdN(CH2)3) (13). The solid state structures of 5, 11, 12, and 13 are reported.
A comparative study of the electrochemical properties of 5 and 1 is also reported.
In tr od u ction
to perform a similar study of the reactions of alkynes
with the µ3-η2-imidoyl clusters of ruthenium and os-
mium. We report here the results of these investiga-
tions, with Ru3(CO)9(µ3-η2-CH3CdNCH2CH3)(µ-H) (1)
and M3(CO)9(µ3-η2-CdN(CH2)3)(µ-H) (M ) Ru, 2; M )
Os, 3), where we observe an even greater variety in
reactivity and structural type for related osmium and
ruthenium systems than that observed with other
In previous papers, we and others have reported the
reactions of µ3-η2-imidoyl clusters with CO, PPh3, and
MeNC.1-3 In addition to the expected greater reactivity
of the triruthenium derivatives relative to their osmium
analogs, we also observed a remarkable sensitivity to
the substituent on the nitrogen atom in the observed
structures of the products and on the mechanisms of
the reported dynamical processes for both metals.
Given the previously reported reactivity of triruthenium
clusters containing nitrogen heterocycles toward alkynes4
and the activity of the resulting alkyne derivatives as
hydrogenation catalysts,5 we thought it would be useful
ligands.
Resu lts a n d Discu ssion
A. Rea ction s of Tr ir u th en iu m a n d Tr iosm iu m
µ3-η2-Im id oyls w ith Alk yn es. The reaction of 1 with
2-butyne at 70 °C leads to a complex mixture of
products, two of which can be isolated in sufficient
amounts to be fully characterized, Ru2(CO)6(µ-η4-C4-
(CH3)4) (4) and Ru3(CO)7(µ-η2:η4-C4(CH3)4)(µ-η2-CH3-
CdNCH2CH3)(η1-COC(CH3)C(H)CH3) (5, eq 1). The solid
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) See previous paper and the reference listed below: (a) Gobetto,
R.; Hardcastle, K. I.; Kabir, S. E.; Milone, L.; Nishimura, N.; Botta,
M.; Rosenberg, E.; Yin, M. Organometallics 1995, 14, 3068 and
references cited therein. (b) Su¨ss-Fink, G.; J enke, T.; Heitz, H.;
Pellinghelli, M. A.; Tiripicchio, A. J . Organomet. Chem. 1989, 379, 311.
(c) Pellinghelli, M. A.; Tiripicchio, A.; Cabeza, J . A.; Oro, L. A. J . Chem.
Soc., Dalton Trans. 1990, 1509. (d) Rosenberg, E.; Kabir, S. E.; Day,
M.; Hardcastle, K. I.; Irving, M. J . Cluster Sci. 1994, 5, 481. (e) Bruce,
M. I.; Wallis, R. C. Aust. J . Chem. 1982, 35, 709. (f) Basu, A.; Bhaduri,
S.; Sharma, K.; J ones, P. G.; Carpenter, G. J . Chem. Soc., Dalton Trans
1990, 1305. (g) Eisenstadt, A.; Giandomenico, C. M.; Frederick, M.
F.; Laine, R. M. Organometallics 1985, 4, 2033. (h) Fish, R. H.; Kim,
T. J .; Stewart, J . L.; Bushweller, J . H.; Rosen, R. K.; Dupon, J . W.
Organometallics 1986, 5, 2193. (i) Casey, C. P.; Widenhoefer, R. A.;
Hallenbeck, S. L.; Hayashi, R. K.; Gavney, J . A. Organometallics 1994,
13, 4720. (j) McKenna, S. T.; Andersen, R. A.; Muetterties, E. L.
Organometallics 1986, 5, 2233.
(2) Day, M.; Espitia, D.; Hardcastle, K. I.; Kabir, S. E.; Rosenberg,
E.; Gobetto, R.; Milone, L.; Osella, D. Organometallics 1991, 10, 3550.
(3) Day, M.; Espitia, D.; Hardcastle, K. I.; Kabir, S. E.; McPhillips,
T.; Rosenberg, E.; Gobetto, R.; Milone, L.; Osella, D. Organometallics
1993, 12, 2304.
state structure of 5 is shown in Figure 1, crystal data
S0276-7333(96)01091-6 CCC: $14.00 © 1997 American Chemical Society

Triruthenium and Triosmium µ3-η2-Imidoyls
Organometallics, Vol. 16, No. 12, 1997 2675
Ta ble 1. Cr ysta l Da ta for 5, 11, 12, a n d 13
5
11
12
13
empirical formula
fw
temperature, K
wavelength, Å
cryst syst
space group
a, Å; R, deg
C
24H27NO8Ru3
C26H17NO8Os3
1042.03
293(2)
0.710 73
monoclinic
P21/n
12.227(2); 90
16.659(2); 100.90(2)
13.464(3); 90
2693(2); 4
2.57
C19H13NO13Os3
1033.90
293(2)
0.710 73
monoclinic
P21/n
10.561(2); 90
20.688(4); 90.31(3)
11.336(2); 90
2476.6(9); 4
2.770
C20H19NO8Os3
971.97
293(2)
0.710 73
monoclinic
P21/n
8.916(1); 90
22.359(5); 95.65(1)
12.078(2); 90
2395(3); 4
2.69
760.68
293(2)
0.710 73
triclinic
P1h
9.141(2); 93.24(3)
9.139(2); 95.42(3)
18.848(4); 115.44(3)
1407.2(5); 2
1.795
b, Å; â, deg
c, Å; γ, deg
volume, Å3; Z
density (calcd), g/cm3
abs coeff, cm-1
F(000)
16.33
748
0.5 × 0.05 × 0.5
141.9
1888.0
154.19
1860
159.4
1748
crystal size, mm3
0.30 × 0.30 × 0.40
0.60 × 0.45 × 0.40
0.10 × 0.07 × 0.27
θ range for data collection, 1.09-26.97
deg
2.0-23.0
1.97-26.79
2.0-23.0
limiting indices
-11 e h e 11, -10 e k e 10, -13 e h e 13, 0 e k 18,
-22 e l e 22 -14 e l e 14
-12 e h e 12, -24 e k e 24, -9 e h e 9, 0 e k e 24,
-13 e l e 13 -13 e l e 13
abs corr
ψ
ψ
ψ
ψ
no. of reflns collected
no. of independent reflns
refinement method
12214
8480
17470
7184
6107 (Rint ) 0.023)
full-matrix least-squares
on F2
4078 (Rint ) 0.050)
full-matrix least-squares
on F2
4372 (Rint ) 0.090)
full-matrix least-squares
on F2
3435 (Rint ) 0.029)
full-matrix least squares
on F2
data/restraints/parameters 6107/0/316
2706/0/343
0.90
4372/0/325
1.187
3435/0/289
0.96
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)a
1.719
R1 ) 0.0462, wR2 ) 0.0802 R1 ) 0.0257, wR2 ) 0.0307 R1 ) 0.0427, wR2 ) 0.0879 R1 ) 0.0300, wR2 ) 0.0334
R1 ) 0.0643, wR2 ) 0.0733
R1 ) 0.0544, wR2 ) 0.0926
1.783 and -1.564
largest diff peak and hole, 0.936 and -0.767
0.48(18)
0.74(20)
e Å-3
a
Not available for compounds 11 and 13.
Ta ble 2. Selected Dista n ces (Å) a n d An gles (d eg)
for 5a
Distances
Ru(1)-Ru(2)
Ru(1)-Ru(3)
Ru(2)-Ru(3)
Ru(3)-C(1)
Ru(1)-N(1)
Ru(1)-C(5)
Ru(2)-C(40)
Ru(2)-C(43)
Ru(3)-C(40)
Ru(3)-C(41)
Ru(3)-C(42)
Ru(3)-C(43)
Ru-COb
3.073(1)
2.897(1)
2.780(2)
2.082(6)
2.081(5)
2.032(7)
2.053(6)
2.060(6)
2.259(6)
2.240(6)
2.252(6)
2.254(6)
1.859(7)
C(1)-N(1)
C(5)-O(1)
C(5)-C(6)
C(40)-C(41)
C(41)-C(42)
C(42)-C(43)
C-Ob
1.255(2)
1.202(7)
1.476(9)
1.388(7)
1.450(8)
1.374(8)
1.153(7)
Angles
F igu r e 1. Solid state structure of 5.
Ru(1)-Ru(2)-Ru(3)
Ru(1)-Ru(2)-Ru(3)
Ru(1)-Ru(3)-Ru(2)
Ru(21)-Ru(1)-Ru(3)
Ru(21)-Ru(1)-Ru(3)
C(1)-Ru(3)-Ru(2)
N(1)-Ru(1)-Ru(2)
C(5)-Ru(1)-Ru(2)
59.07(3) C(2)-C(1)-N(1)
59.07(3) C(1)-N(1)-C(3)
65.52(3) O(1)-C(5)-C(6)
55.41(3) C(5)-C(6)-C(2)
121.1(5)
124.9(5)
118.7(7)
117.1(7)
are given in Table 1, and selected distances and bond
angles are given in Table 2. The structure of 5 consists
of an Ru3 triangle with a µ-η2-imidoyl ligand bridging
the Ru(1)-Ru(3) edge, a metallocyclopentadienyl moiety
containing Ru(2) and η4-π-bound to Ru(3), and an η1-
vinyl acyl attached to Ru(1). The Ru(1)-Ru(2) bond
length of 3.073(1) Å is extremely long, but is a required
metal-metal bond considering that 5 is a 48e- cluster.
As expected, the µ-imidoyl carbon-nitrogen bond is
shortened (1.255(2) Å) relative to the triruthenium µ3-
imidoyls previously reported.6-8 The imidoyl-carbon-
Ru(3) and the N-Ru(1) bonds are also somewhat
elongated relative to those in the phosphine-substituted
derivatives of 1.1,6 The Ru(1)-C(5) bond is typical for
η1-ruthenium acyls,9 and the carbon-carbon bond (C(5)-
C(6) ) 1.476(9) Å) is elongated with respect to that
55.41(3) C(40)-C(41)-C(42) 112.3(5)
98.8(2)
90.9(2)
110.0(2)
C(41)-C(42)-C(43) 116.0(5)
Ru-C-Ob
176.0(7)
a
Numbers in parentheses are estimated standard deviations.
Average values.
b
expected for an uncoordinated double bond. The in-
traligand distances for the metallocyclopentadienyl
group are typical for related compounds such as direct
analogs of 4.10 The H-NMR of 5 in solution is entirely
1
consistent with the solid state structure. Six singlet
methyl resonances are observed in the range 2.0-2.5
ppm, and one methyl doublet at 1.95 ppm which is
coupled to a quartet at 6.35 ppm is assignable to the
vinylic hydrogen. The methylene resonances of the
ethyl group appear as the expected pair of AB multiplets
at 3.91 and 3.61 ppm and are coupled to a triplet at 1.12
ppm.
In sharp contrast to the results obtained from the
reaction of 1 with 2-butyne, compound 2 reacts with
2-butyne to give one compound, Ru3(CO)8(µ3-η2-
CdN(CH2)3)(µ-η2-CH3CC(H)CH3) (6, eq 2),
(4) (a) Cabeza, J . A.; Fernandez-Colinas, J . M.; Llamazares, A.;
Riera, V.; Garcia-Grande, S.; Van der Maelen, J . F. Organometallics
1994, 13, 4352. (b) Lugan, N.; Laurent, F.; Lavigne, G.; Newcomb, T.
P.; Liimatta, E. W.; Bonnet, J . J . Am. Chem. Soc. 1990, 112, 8607. (c)
Nombel, P.; Lugan, N.; Mulla, F.; Lavigne, G. Oroganometallics 1994,
13, 4673.
(5) Cabeza, J . A.; del Rio, I.; Fernandez-Colinas, J . M.; Riera, V.
Organometallics 1996, 15, 449.

2676 Organometallics, Vol. 16, No. 12, 1997
Kabir et al.
resonances of the same relative intensity as the doublet
methyl resonances are also observed at 2.99 and 2.29
ppm. Complexation of the vinyl group in a µ-η2-σ-π
bonding mode leads to an upfield shift of the vinyl
hydrogen while the η1-vinyl hydrogen would be expected
to be found downfield. The 1H-NMR data for the vinylic
hydrogens in 5 and 6 illustrate this trend nicely (6.35
and 2.16 ppm, respectively). Further evidence for the
proposed structures of 8 and 9 comes from the 13C-NMR
of the mixture which shows four resonances assignable
to the CdN carbons at 216.33, 213.13, 212.14, and
189.86 ppm in a relative intensity of 1:0.3:0.8:0.2. The
three most downfield resonances can be assigned to
π-complexed imidoyl carbons in the three possible
isomers of 8 since these are usually found in the range
210-220 ppm in related complexes.1 The resonance at
189.86 ppm can be assigned to the imidoyl carbon in 9
since this type of resonance is found in the 190-200
ppm range (this type of carbon is observed at ∼198 ppm
in 12, reported below).1 Two well-resolved CH reso-
nances are also observed at 112.79 and 94.57 ppm,
which can be assigned to vinylic resonances in 8 (the
π-complexed vinylic CH in 10 reported below comes at
77.27 ppm). In addition, the presence of minor isomers
is also evident in the 1H-NMR from the presence of
lower intensity methyl singlets, doublets, and methylene
multiplets. This spectral complexity of the isomeric
mixture of 8 and 9 is attributable to the presence of
conformers for 9 where the associated vinyl hydrogen
quartets overlap with other ligand resonances. We
cannot exclude the possibility that the lower intensity
signals observed are due to other types of isomers which
differ by the location of vinyl group on the osmium
triangle or even binuclear species. Variable-tempera-
ture studies to see if 8 and 9 are in equilibrium were
precluded by their conversion to 10 on heating (see
below).
whose structure is assigned on the basis of spectroscopic
evidence and by analogy with closely related triruthe-
nium 2-amino-6-methylpyridine complexes4,5 and with
the osmium analogs presented below. As for the reac-
tions of 1 and 2 with phosphines, the presence of the
ethyl group in 1 significantly alters the course of the
reaction relative to the less sterically encumbered µ3-
η2-imidoyl 2. One can visualize initial formation of an
analog of 6 which then converts to an η1-vinyl acyl to
relieve steric crowding. This, in turn, would create
multiple vacant coordination sites which could then
react further with alkyne to form 5 and perhaps
fragment to form 4.
Compound 3 does not react with 2-butyne at all even
at elevated temperatures. It does react with less
volatile alkynes but only at 100 °C (vide infra). Thus,
the triosmium imidoyls are less reactive toward alkynes
than their triruthenium analogs.1 We recently reported
that the decacarbonyl precursor to 3, Os3(CO)10(µ-η2-
CdN(CH2)3)(µ-H)(7a ) undergoes reaction with trimeth-
ylamine N-oxide in acetonitrile/methylene chloride re-
giospecifically (eq 3).11 The resulting acetonitrile de-
Thermolysis of the mixture of 8 and 9 at 100 °C
results in conversion to a single product Os3(CO)8(µ3-
η2-CdN(CH2)3)(µ-η2-CH3CdC(H)CH3) (10, eq 5). Com-
rivative Os3(CO)9(µ-η2-CdN(CH2)3)(µ-H)(CH3CN) (7b)
does react smoothly with C2(CH3)2 at ambient temper-
atures to give a single product band on purification by
thin layer chromatography which proved to be an
inseparable mixture of isomers. On the basis of the 1H-
NMR data, we can tentatively assign the structures
which comprise this mixture to two major types: Os3-
(CO)9(µ3-η2-CdN(CH2)3)(η1-CH3CdC(H)CH3) (8) and Os3-
(CO)9(µ-η2-CdN(CH2)3)(µ-η2-CH3CdC(H)CH3) (9, eq 4).
pound 10 was characterized spectroscopically and by
elemental analysis. A similar mixture of isomers to that
found in the reaction of 2-butyne with 7b is isolated
from the reaction of 7b with diphenylacetylene at
ambient temperatures. On thermolysis this mixture
gives one compound, Os3(CO)8(µ3-η2-CdN(CH2)3)(µ-η2-
C6H5CdC(H)C6H5) (11). Compound 11 is also obtained
in moderate yield by direct reaction of 3 with diphen-
ylacetylene in refluxing heptane. Compound 11 was
characterized spectroscopically and by a solid state
structural investigation. The solid state structure of 11
These assignments are based on the observation of two
different quartet resonances at 3.93 and 6.90 ppm which
are coupled to two different methyl group doublets at
2.58 and 2.10 ppm, respectively. Two singlet methyl

Triruthenium and Triosmium µ3-η2-Imidoyls
Organometallics, Vol. 16, No. 12, 1997 2677
F igu r e 2. Solid state structure of 11.
Ta ble 3. Selected Dista n ces (Å) a n d Bon d An gles
(d eg) for 11a
F igu r e 3. Solid state structure of 12.
Distances
in length at 2.16(1) and 2.17(1) Å, while the Os(2)-C(6)
bond length is considerably longer at 2.31(1) Å. This
overall disposition results in an effective π-interaction
with Os(2) and σ-interaction with Os(3). This type of
bonding mode is well documented for the alkyne deriva-
tives of the triruthenium µ3-η2-2-amino-6-methylpyri-
dine clusters,4,5 but 10 and 11 are the first triosmium
clusters with both σ-π-vinyl and a face-capping nitrogen
heterocycle. The η1-vinyl coordination proposed for 8
has been suggested as an intermediate in the hydroge-
nation of alkynes catalyzed by the 2-amino-6-methylpy-
ridine analogs of 11.5
In the hope of stabilizing a nonacarbonyl complex of
the types proposed for 8 and 9, we reacted 7b with the
electron poor alkyne, C2(CO2CH3)2. In fact, an apparent
nonacarbonyl cluster, Os3(CO)9(µ-η2-CdN(CH2)3)(µ3-η3-
CH3O2CdC(H)CO2CH3) (12) was isolated as the only
major product from the reaction of 7b with this alkyne
at ambient temperatures or from its reaction with 3 at
100 °C (eqs 6 and 7). However, the structure of 12
Os(1)-Os(2)
Os(1)-Os(3)
Os(2)-Os(3)
Os(1)-C(1)
Os(2)-N
2.7067(7)
2.8939(7)
2.7106(6)
2.06(1)
2.17(1)
2.30(1)
2.14(1)
2.16(1)
2.31(1)
2.17(1)
1.91(1)
C(1)-N
1.36(2)
1.45(2)
1.50(2)
1.54(2)
1.55(2)
1.55(2)
1.52(2)
1.49(2)
1.14(2)
C(5)-C(6)
C(4)-N
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(5)-C(51)
C(6)-C(61)
C-Ob
Os(2)-C(1)
Os(3)-N
Os(2)-C(5)
Os(2)-C(6)
Os(3)-C(5)
Os-COb
Angles
64.58(2)
Os(1)-Os(2)-Os(3)
Os(1)-Os(3)-Os(2)
Os(2)-Os(1)-Os(3)
Os(3)-Os(2)-N
Os(1)-Os(2)-C(1)
Os(3)-Os(2)-C(6)
Os(2)-C(5)-Os(3)
Os-C-Ob
N-C(1)-C(2)
111(1)
112(1)
124(1)
120(1)
57.64(2)
57.78(3)
50.6(2)
47.8(3)
77.0(3)
77.6(4)
177(1)
C(1)-N-C(4)
C(5)-C(6)-C(61)
C(6)-C(5)-C(51)
a
Numbers in parentheses are estimated standard deviations.
Average values.
b
is shown in Figure 2, crystal data are given in Table 1,
and selected distances and bond angles are given in
Table 3. Compound 11 consists of an isosceles triangle
of osmium atoms with a µ3-imidoyl ligand bridging the
elongated Os(1)-Os(3) edge and the carbon-nitrogen
double bond being coordinated to Os(2). The σ-π-vinyl
ligand bridges the Os(2)-Os(3) edge which is virtually
identical in length with the Os(1)-Os(2) edge. The
geometry of the µ3-imidoyl ligand is distinctly different
from related face-capping imidoyls in that the Os(3)-N
and Os(2)-N bond lengths are almost equal, being
2.14(1) and 2.17(1) Å, respectively.1-3 The Os(1) and
C(1) and Os(2) and C(1) distances are more typical at
2.06(1) and 2.30(1) Å, respectively. The corresponding
bond lenghts in 3 are 2.08(1) and 2.30(1) Å.3 The Os-
(2)-C(5) and Os(3)-C(5) vectors are also almost equal
(6) (a) Hansert, B.; Tasi, M.; Tiripicchio, A.; Tiripicchio-Camellini,
M.; Vahrenkamp, H. Organometallics 1991, 10, 4070. (b) Basu, A.;
Bhaduri, S.; Sharma, K.; J ones, P. G. J . Chem. Soc., Chem. Commun.
1987, 1126.
(7) Aime, S.; Gobetto, R.; Padovan, F.; Botta, M.; Rosenberg, E.;
Gellert, R. W. Organometallics 1987, 6, 2074.
(8) Day, M. W.; Hajela, S.; Kabir, S. E.; Irving, M.; McPhillips, T.;
Wolf, E.; Hardcastle, K. I.; Rosenberg, E.; Milone, L.; Gobetto, R.;
Osella, D. Organometallics 1991, 10, 2743.
(9) Mayr, A.; Lin, Y. C.; Boag, N. M.; Kaesz, H. D. Inorg. Chem.
1982, 21, 1704.
(10) Osella, D.; Arman, G.; Gobetto, R.; Laschi, F.; Zanello, P.;
Ayrton, S.; Goodfellow, V.; Housecroft, C. E.; Owen, S. M. Organome-
tallics 1989, 8, 2689 and references therein.
(11) Rosenberg, E.; Kabir, S. E.; Day, M.; Hardcastle, K. I.; Wolf,
E.; McPhillips, T. Organometallics 1995, 14, 721.
proved to be quite different from that proposed for either
8 or 9. The solid state structure of 12 is shown in Figure
3, crystal data are given in Table 1, and selected
distances and angles are given in Table 4. Compound
12 is a 50e- cluster with two unequal metal-metal
bonds, Os(1)-Os(2) at 2.969(1) Å and Os(2)-Os(3) at
2.746(1) Å. The imidoyl ligand bridges the open metal-

2678 Organometallics, Vol. 16, No. 12, 1997
Kabir et al.
Ta ble 4. Selected Dista n ces (Å) a n d An gles (d eg)
for 12a
Distances
Os(1)-Os(2)
Os(2)-Os(3)
Os(1)-N(1)
2.969(1)
2.746(1)
2.09(1)
C(1)-N(1)
C(7)-C(8)
C(9)-O(4)
C(6)-O(2)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-N(1)
C(7)-C(6)
C(8)-C(9)
C-Ob
1.36(2)
1.48(2)
1.91(1)
1.24(2)
1.52(2)
1.58(2)
1.55(2)
1.54(2)
1.44(2)
1.56(2)
1.11(2)
Os(3)-C(1)
Os(1)-C(7)
Os(1)-C(8)
Os(2)-C(8)
Os(3)-C(8)
Os-COb
2.22(1)
2.20(1)
2.39(1)
2.57(1)
2.10(1)
1.95(2)
2.16(2)
Os(2)-O(4)
Angles
Os(1)-Os(2)-Os(3)
Os(1)-Os(2)-O(4)
N(1)-Os(1)-C(7)
Os(3)-Os(2)-C(8)
82.08(2)
91.9(2)
81.3(4)
46.3(2)
N(1)-Os(1)-C(8)
N(1)-Os(1)-Os(2)
Os-C-Ob
84.0(4)
90.9(3)
177(1)
a
Numbers in parentheses are estimated standard deviations.
Average values.
b
metal bond with Os(1)-N at 2.09(1) Å and Os(3)-C(1)
at 2.22(1) Å. The latter is considerably elongated
relative to other µ-imidoyls (2.06-2.10(1) Å) as might
be expected since it is bridging a nonbonded metal
vector. Each osmium atom is bound to three carbonyl
groups, but Os(2) is also bound to the carbonyl oxygen
of one of the carbomethoxy groups of the alkyne. The
alkyne carbons C(7) and C(8) are π-bound to Os(1) with
bond lengths that are fairly typical for such interactions
at 2.20(1) and 2.39(1) Å.4,5 The Os(3)-C(8) bond length
of 2.10(1) Å is typical for an osmium-carbon σ-bond
while the Os(2)-C(8) at 2.57(1) Å must be considered a
fairly weak interaction since it is nearly the sum of the
covalent radii of these two elements (2.67 Å) and is very
elongated compared with most osmium-carbon
σ-bonds.1-5 In a general way 12 resembles the structure
proposed for 9, containing a µ-η2-imidoyl, a µ-η2-vinyl,
and nine carbonyls. However, it is apparently the
additional interaction with the organic carbonyl which
makes 12 prefer this bonding mode over the µ3-η2-
imidoyl and η1-vinyl and prevents 12 from existing as
a complex mixture of isomers while stabilizing the
nonacarbonyl derivative. A similar carbonyl oxygen
interaction accompanied by metal-metal bond rupture
has been observed in dirhenium complexes of dicar-
bomethoxyacetylene.12
F igu r e 4. Solid state structure of 13.
Ta ble 5. Selected Dista n ces (Å) a n d Bon d An gles
(d eg) for 13a
Distances
Os(1)-Os(2)
Os(1)-Os(3)
Os(2)-Os(3)
Os(2)-N
Os(2)-C(4)
Os(2)-C(40)
Os(3)-C(42)
Os(3)-C(44)
Os(3)-C(46)
Os-C-Ob
2.730(1)
2.889(1)
2.846(1)
2.15(1)
2.21(1)
2.26(1)
2.32(1)
2.24(1)
2.26(1)
1.86(2)
C(4)-N(1)
C(4)-C(40)
C(40)-C(42)
C(42)-C(44)
C(44)-C(46)
N(1)-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C-Ob
1.43(2)
1.38(2)
1.52(2)
1.49(2)
1.41(2)
1.51(3)
1.57(2)
1.59(2)
1.52(2)
1.17(2)
Angles
62.38(2)
56.85(2)
60.77(2)
47.3(3)
71.9(3)
134(2)
102.2
36.4(5)
177(1)
Os(1)-Os(2)-Os(3)
Os(1)-Os(3)-Os(2)
Os(2)-Os(1)-Os(3)
Os(3)-Os(2)-N
Os(3)-Os(2)-C(4)
Os(1)-Os(2)-C(40)
Os(1)-Os(2)-C(42)
C(44)-Os(3)-C(46)
Os-C-Ob
C(1)-N-C(4)
110(1)
N-C(4)-C(1)
111(1)
118(1)
119(1)
118(1)
124(1)
N-C(4)-C(40)
C(4)-C(40)-C(42)
C(42)-C(44)-C(46)
C(44)-C(46)-C(47)
a
Numbers in parentheses are estimated standard deviations.
Average values.
b
diffraction study. The solid state structure of 13 is
shown in Figure 4, crystal data are given in Table 1,
and selected distances and angles are given in Table 5.
The structure of 13 consists of an Os3 triangle with four
carbonyl groups on Os(1) and two carbonyl groups on
Os(2) and Os(3). The Os(2)-Os(3) edge is bridged by a
single organic ligand consisting of two coupled 2-bu-
tynes, one of which is joined to the pyrrolidine ring at
the imidoyl carbon. The ligand is an eight-electron
donor which essentially raps around the Os(2)-Os(3)
edge. The carbon nitrogen double bond is considerably
elongated (1.43(2) Å) relative to other π-coordinated
imidoyls (∼1.35 Å).1-3 The C(40)-Os(2) and C(42)-Os-
(3) bond lengths of 2.26(1) and 2.32(1) Å taken together
with the C(40)-C(42) bond length of 1.52(2) indicate
that the Os(2)-Os(3)-C(40)-C(42) is a dimetallacy-
clobutane. The C(44)-C(46) bond length of 1.41(2) and
the associated Os(3)-C(46) and C(44)-Os(3) distances
of 2.26(1) and 2.24(1) Å indicate that this vinyl fragment
interacts only with Os(3). The N-Os(3) bond length of
2.10 Å is fairly typical for µ-imidoyls.1-5 Although the
oligomerization of alkynes on clusters is fairly com-
mon,13 coupling to a nitrogen heterocycle is rare and is
reminiscent of the ruthenium carbonyl catalyzed cou-
The compounds 9-12 show no tendency to react
further with alkynes. Both straight thermal reactions
and reactions in the presence of trimethylamine N-oxide
failed to yield any new products, with nonspecific
decomposition or recovery of starting material being the
only reaction pathways observed. However, reaction of
7a with 2 mol of trimethylamine N-oxide in the presence
of 2-butyne at room temperature did result in the
formation of Os3(CO)8(µ-η6-(CH3C(H)dC(CH3)C(CH3)dC-
(CH3)CdN(CH2)3) (13, eq 8) as well as considerable
nonspecific decomposition.
Compound 13 was characterized by 1H-NMR and
infrared spectroscopy and by a single-crystal X-ray
(12) Adams, R. D.; Huang, M. Organometallics 1995, 14, 2887.
(13) Shore, N. E. Chem. Rev. 1988, 88, 1081.

Triruthenium and Triosmium µ3-η2-Imidoyls
Organometallics, Vol. 16, No. 12, 1997 2679
F igu r e 6. Cyclic voltammogram of 5 at 300 mV s-1 (solid
F igu r e 5. Cyclic voltammograms of 1 (solid line) and
Ru3(CO)10(µ-η2-CH3CdNCH2CH3)(µ-H) (dashed line) at 200
line) and at 200 mV s-1 (dashed line).
mV s-1
.
response consists of a new 1e chemically irreversible
reduction, peak C, at less negative potential [Ep(C) )
1.28 V] followed in the reverse scan by two peaks, D
and E, at -0.63 and -0.43 V, respectively, due to the
reoxidation of fragments (Figure 5). All of the electro-
chemical features for the decacarbonyl are similar to
those found for 1 and suggest an EC mechanim. By
comparison of the polarographic E1/2 values of 1 and the
decacarbonyl, -1.43 and -1.24 V, respectively, it can
be concluded that the addition of a further CO group
which displaces the coordination of the CdN bond
(originally present in 1) decreases the electron density
on the Rui3 triangle, making the reduction easier as
would be expected from replacing the CdN bond π-co-
ordination with a better π-acceptor ligand.
The electrochemical behavior of 5 is completely dif-
ferent from that of 1 or the corresponding decacarbonyl.
The CV response of an acetone solution of 5 at an
HMDE is shown in Figure 6. Two reduction peaks are
observed at -1.17 and -1.33 V at a scan rate of 0.300
V s-1. The Ep - Ep/2 values of 49 and 66 mV make these
reduction waves close to 1e- Nernstian behavior. The
less cathodic values observed for these sequential 1e-
reductions clearly show that the site of reduction is
different for 5 relative to 2. Indeed, some related
trinuclear complexes of the general formula M3(CO)8-
(R2C2)2 (M ) Fe, Ru, Os; R ) Me, Et, Ph) which have
the µ-η2:η4-metallocyclopentadiene structure exhibit
similar electrochemical behavior, having 1e- reversible
reductions in the range 1.16-1.42 V.10 It is reasonable
that the more delocalized metallocyclopentadienyl moi-
ety would have the lowest energy orbital for accepting
electrons. Interestingly, the µ3-η4-C4R4 clusters undergo
only a 1e- reversible reduction and then fragment to
µ-η4-dimetallic species, similar to 4, upon accepting a
second electron.10
pling of olefins and carbon monoxide to pyridines to
yield vinylacylpyridines.14 The vinylic hydrogen on
C(46) appears at a quartet at 1.75 ppm. This unusually
high field chemical shift is probably the result of the
observed orientation of the C(44)-C(46) vector which
points this hydrogen directly at Os(3). The formation
of 13 from the reaction of 7a with 2 mol of trimethyl-
amine N-oxide and 2-butyne but not from 9 and 12
suggests that multiple coordination sites must be si-
multaneously available for the observed coupling as was
suggested for the formation of 5.
B. Electr och em ica l Beh a vior of 1 a n d 5. Com-
plex 5 represents an unusual example of a cluster
containing three distinct organic moieties which are
well-known as individual ligands but have never been
observed together. The low yield obtained for 5 pre-
cluded detailed investigations of its chemistry, and we
thought electrochemical measurements would provide
an efficient means of making a preliminary probe of its
electronic properties. For comparison, we have also
investigated the electrochemical behavior of 1.
The CV response of an acetone solution of 1 at a
hanging mercury drop electrode (HMDE) is reported in
Figure 5. The reduction process at peak A [Ep(A) )
-1.47 V] is chemically irreversible. In fact, no associ-
ated reoxidation peak could be found at scan rates as
high as 1 V s-1 and at temperatures as low as -20 °C.
In the reverse scan a small peak, B, is observed at -0.76
V, attributable to the reoxidation of fragment product-
(s). The breadth of the peak measured at the half-width
(Ep - Ep/2) is 67 mV, close to 1e- Nernstian behavior.10
The plot of ip vs V1/2 (the scan rate varying from 50 to
1000 mV s-1) is linear through the origin, confirming
the diffusion-controlled behavior.10 Besides this CV
data, evidence of fast 1e transfer comes from the 65 mV
slope10 of the plot of E vs log[(id - i)/i] obtained from
the polarographic wave (E1/2 ) -1.43 V). The plot of
Ep vs log v gives a slope of 38 mV, indicating the one-
electron reduction is followed by a moderately fast, first-
order chemical decomposition (EC mechanism). The
polarographic response of an equimolar solution of 1 and
ferrocene in acetone gives a current ratio equal to 0.9,
confirming that wave A corresponds to a one-electron
reduction process.
Exp er im en ta l Section
Compounds 1-3 were synthesized by known literature
procedures.1f,2,3 All reactions were performed under an atmo-
sphere of prepurified nitrogen, but were worked in the air.
Thin layer chromatography was performed on 20 × 20 or 20
× 40 cm plates using a 1 mm layer of silica gel PF-254 (E&M
Science). Methylene chloride was distilled from CaH2 before
use, and hexane was dried over sodium. Trimethylamine
N-oxide (Aldrich) was dehydrated by distillation of the water-
toluene azeotrope. Alkynes were purchased from Farchan and
used as received. 1H- and 13C-NMR were obtained on a Bruker
360-AMX or a Varian 400 Unity Plus spectrometer. Infrared
spectra were obtained on PE-1620 or 1400 spectrometers.
Bubbling CO into an acetone solution rapidly turns
1 into Ru3(CO)10(µ-η2-CH3CdNCH2CH3)(µ-H). The CV
(14) Moore, E. J .; Pretzer, W. R.; O’Connell, T. J .; Harris, J .;
LaBounty, L.; Chou, L.; Grimmer, S. S. J . Am. Chem. Soc. 1992, 114,
5888.

2680 Organometallics, Vol. 16, No. 12, 1997
Kabir et al.
Elemental analyses were performed by Schwarzkopf Mi-
croanalytical Labs, New York.
evaporated and purified by thin layer chromatography using
1:4 methylene chloride/hexanes as eluent. Two major bands
were eluted: the faster moving yellow band contained 62 mg
(55%) of Os3(CO)9(CdN(CH2)3)(CH3CdC(H)CH3) (8 and 9), and
the slower moving orange band contained 21 mg (19%) of Os3-
(CO)8(µ3-η2-CdN(CH2)3)(µ-η2-CH3CdC(H)CH3) (10).
Electr och em ica l Mea su r em en ts. Voltammetric and po-
larographic measurements were performed with two sets of
instrumentation: a PAR 273 electrochemical analyzer con-
nected to an interfaced PC and an AMEL 553 potentiostat
modulated by an AMEL 567 function generator and connected
to an X-Y recorder.
An a lytica l a n d Sp ectr oscop ic Da ta for 8 a n d 9. IR (ν-
(CO), hexane): 2104 (w), 2092 (m), 2071 (s), 2064 (s), 2054
(s), 2045 (s), 2038 (s), 2022 (s), 1992 (s, br), 1974 (s, br), 1966
A three-electron cell was designed to allow the tip of the
reference electrode (SCE) to closely approach the working
electrode. Compensation for the IR drop was applied through
positive-feedback device. All measurements were carried out
under nitrogen in anhydrous deoxygenated solvents. Solutions
were 1 × 10-3 M for the compounds under study and 1 × 10-1
M for the supporting electrolyte, [Bu4N][BF4]. The tempera-
ture of the solution was kept constant ((1 °C) by circulation
of a thermostated water/ethanol mixture through a jacketed
cell. The working electrode was a hanging mercury drop
electrode (HMDE), or dropping mercury electrode (DME).
Potential data (vs SCE) were checked against the ferrocene
(0/1+) couple; under the actual experimental conditions, the
ferrocene/ferrocenium couple is located at +0.51 V in acetone.
Rea ction of 1 w ith 2-Bu tyn e. 1 (400 mg, 0.64 mmol) was
combined with 0.150 mL (1.9 mmol) 2-butyne and 250 mL of
degassed hexane. The yellow solution was heated at reflux
for 4 h. The dark red solution was filtered, rotary evaporated,
taken up in methylene chloride, and purified by thin layer
chromatography. Three major bands were eluted: the fastest
moving band contained unreacted 1, 22 mg, the second yellow
band contained Ru2(CO)6[µ-η1:η1:η4-(C4(CH3)4)] (4) (31 mg,
10%), and the third red band contained 32 mg (7%) of Ru3-
(CO)7(µ-η2:η4-C4(CH3)4)(µ-η2-CH3CdNCH2CH3)(η1-COC(CH3)C-
(H)CH3) (5).
(s, br), 1941 (w) cm-1 1H-NMR (CDCl3, 400 MHz) mixture of
.
8 and 9 of equal relative intensity: 6.90 (q, 1H), 3.93 (q, 1H),
3.90-3.45 (multiplets, ∼4H), 3.14 (m, 0.6H), 2.99 (s, 3H), 2.87
(m, 1H), 2.58 (m, 2H), 2.39 (s, 3H), 2.29 (d, 3H), 2.10 (d, 3H),
1.76 (m, 1H) ppm. Not all of the methylene resonances could
be assigned due to overlap. Other methyl doublets of lower
relative intensity were observed at 2.14 and 2.24 ppm.
An a lytica l a n d Sp ectr oscop ic Da ta for 10. Anal. Calcd
for C16H13O8NOs3: C, 20.92; H, 1.41; N, 1.52. Found: C, 21.11;
H, 1.39; N, 1.57. IR (ν(CO), hexane): 2079 (m), 2059 (s), 2048
(s), 2024 (m), 2004 (vs), 1963 (w), 1941 (m, br) cm-1 1H-NMR
.
NMR (CDCl3, 400 MHz): 4.10 (q, 1H), 3.30 (dd, 1H), 2.98 (m,
3H), 2.76 (s, 3H), 2.31 (d, 3H), 1.82 (m, 1H), 1.43 (m, 1H) ppm.
13C-NMR (CDCl3, 100 MHz) carbonyl region: 186.19, 185.96,
185.58, 180.27, 178.24, 177.56, 176.23, 175.74 ppm; hydrocar-
bon region: 73.14 (CH2), 62.96 (CH2), 51.55 (CH), 36.13 (CH2),
25.34 (CH3), 19.10 (CH3) ppm. Thermolysis of the yellow band
containing 8 and 9 in refluxing heptane led to conversion to
10 in about 90% yield after recrystallization.
Syn th esis of Os3(CO)8(µ3-η2-CdN(CH2)3)(µ-η2-C6H5CdC-
(H)C6H5) (11). A procedure identical to that described for the
preparation of 10 was used for the synthesis of 11 except that
the orange and yellow bands obtained from the reaction were
combined and thermalyzed directly to yield 20 mg (30%) of
Os3CO8(µ3-η2-CdN(CH2)3)(µ-η2-C6H5CdC(H)C6H5) (11) from 58
mg of 7a . Somewhat lower yields were obtained by heating 3
with excess diphenylacetylene in refluxing heptane.
An a lytica l a n d Sp ectr oscop ic Da ta for 5. Anal. Calcd
for 5 (C24H27O8NRu3): C, 37.89; H, 3.55; N, 1.84. Found: C,
37.06; H, 3.40; N, 1.89. IR (ν(CO), C6H6): 2077 (m), 2041 (s),
2023 (s), 2008 (vs), 1988 (m, br), 1976 (m, br), 1968 (m, br)
An a lytica l a n d Sp ectr oscop ic Da ta for 11. Anal. Calcd
for for C26H17NO8Os3: C, 30.00; H, 1.63; N, 1.34. Found: C,
30.16; H, 1.82; N, 1.42. IR (ν(CO), hexane): 2077 (m), 2048
cm-1 1H-NMR (CDCl3, 400 MHz): 6.35 (q, 1H), 3.91 (m, 1H),
.
3.61 (m, 1H), 2.51 (s, 3H), 2.43 (s, 3H), 2.29 (s, 3H), 2.11 (s,
3H), 2.04 (s, 3H), 1.95 (d, 3H), 1.83 (s, 3H), 1.12 (t, 3H) ppm.
An a lytica l a n d Sp ectr oscop ic Da ta for 4. Anal. Calcd
for C14H12O6Ru2: C, 35.14; H, 2.50. Found: C, 35.81; H, 2.64.
IR (ν(CO), CH2Cl2) 2067 (m), 2034 (vs), 1998 (m, br), 1991 (m,
(s), 2028 (m), 2004 (vs), 1982 (m), 1962 (w), 1944 (m, br) cm-1
.
1H-NMR (CD2Cl2, 400 MHz): 7.45-6.84 (mm, 10H), 4.84 (s,
1H), 3.57 (m, 1H), 3.12 (m, 2H), 2.91 (m, 1H), 1.88 (m, 1H),
1.39 (m, 1H) ppm.
br), 1971 (m, br) cm-1
6H), 2.21 (s, 6H) ppm.
.
1H-NMR (CDCl3, 80 MHz): 2.37 (s,
Syn t h esis of Os3(CO)9(µ-η2-CdN(CH2)3)(µ3-η3-CH3O2-
CCdC(H)CO2CH3) (12). This complex could be prepared by
the procedure outlined for the preparation of 8, 9, and 10
above. By this procedure, 36 mg (71%) of 12 was obtained
from 45 mg of 7b. Refluxing 42 mg of 3 in the presence of a
5-fold excess of dimethylacetylenedicarbonate in heptane yields
21 mg (43%) of 12.
Syn th esis of Ru 3(CO)8(µ3-η2-CdN(CH2)3)(µ-η2-CH3CdC-
(H)(CH3) (6). 2 (25 mg, 0.04 mmole) was combined with 50
mL of hexane and 0.200 mL (2.5 mmol) of 2-butyne and heated
at reflux for 4 h. The orange yellow reaction mixture was
filtered, rotary evaporated, taken up in minimum methylene
chloride, and purified by thin layer chromatography using 1:4
methylene chloride:hexanes as eluent. Two main bands were
eluted: the first contained 10 mg of recovered 2 and the second
orange band contained 10 mg (35%) of Ru3(CO)8(µ3-η2-CdN-
(CH2)3)(µ-η2-CH3CdC(H)CH3) (6).
An a lytica l a n d Sp ectr oscop ic Da ta for 12. Anal. Calcd
for C19H13O13NOs3: C, 22.07; H, 1.25; N, 1.35. Found: C,
21.96; H, 1.18; N, 1.47. IR (ν(CO), hexane): 2084 (m), 2058
(s), 2034 (s), 2009 (s), 1998 (m, br), 1980 (m, br), 1963 (w, br)
cm-1 1H-NMR (CDCl3, 400 MHz): 3.73 (s, 3H), 3.65 (s, 3H),
.
3.37 (m, 2H), 2.67 (s, 1H), 2.36 (t, 2H), 1.53 (m, 2H) ppm. 13C-
NMR (CDCl3, 100 MHz) carbonyl region: 187.62, 186.27,
184.89, 184.79, 184.58, 180.24, 180.24, 175.41, 175.06, 174.25
ppm; hydrocarbon region: 197.9 (CdN), 173.05 (CO2Me), 70.45
(CH2), 54.99 (CH), 53.87 (CH2), 52.05 (CH2), 40.76 (CH3), 23.71
(CH3) ppm.
Syn th esis of Os3(CO)8(µ-η6-(CH3C(H)dC(CH3)C(CH3)dC-
(CH3)CdN(CH2)3) (13). Compound 7a (35 mg, 0.038 mmol)
was dissolved in 30 mL of methylene chloride and then 12 mg
(0.10 mmol) of trimethylamine N-oxide dihydrate and 50 µL
(0.61 mmol) of 2-butyne were added. The reaction mixture
was stirred at room temperature for 2 h, and the solvent was
evaporated under vacuum and the residue purified by thin
layer chromatography using hexane/CH2Cl2 (10:3) as eluent.
Two bands were eluted: a yellow band which proved to be
unreacted 7a (10 mg), and 7 mg (19%) of 13.
An a lytica l a n d Sp ectr oscop ic Da ta for 6. Anal. Calcd
for C16H13NO8Ru3: C, 29.91; H, 2.04; N, 2.18. Found: C, 29.61;
H, 2.08; N, 2.28. IR (ν(CO), hexane): 2079 (m), 2059 (s), 2048
(s), 2024 (m), 2004 (vs), 1963 (w), 1941 (m, br) cm-1 1H-NMR
.
(CDCl3, 400 MHz): 3.57 (m, 1H), 3.34 (m, 1H), 3.13 (m, 1H),
2.66 (m, 1H), 2.34 (s, 3H), 2.16 (q, 1H), 2.04 (d, 3H), 1.63 (m,
1H), 1.26 (m, 1H) ppm.
Syn t h esis of Os3(CO)9(CdN(CH 2)3)(CH 3CdC(H)CH 3)
Isom er ic Mixtu r e (8 a n d 9) a n d Os3(CO)8(µ3-η2-CdN-
(CH2)3)(µ-η2-CH3CdC(H)CH3) (10). Compound 7a (110 mg,
0.12 mmol) was combined with 20 mL of CH2Cl2 and 10 mL of
CH3CN. Trimethylamine N-oxide (14 mg, 0.18 mmol) in 20
mL of acetonitrile was added dropwise and the reaction
solution stirred for 1 h. The deep yellow solution was filtered
through a short florisil column and rotary evaporated to yield
a yellow oil. A solution of 47 µL of 2-butyne (0.60 mmol) in
20 mL of CH2Cl2 was added dropwise and the red-orange
solution stirred for 1 h. The solution was then rotary
An a lytica l a n d Sp ectr oscop ic Da ta for 13. Anal. Calcd
for C20H19O8NOs3: C, 24.70; H, 1.95; N, 1.44. Found: C, 24.98;

Triruthenium and Triosmium µ3-η2-Imidoyls
Organometallics, Vol. 16, No. 12, 1997 2681
H, 1.84; N, 1.41. IR (ν(CO), hexane): 2075 (m), 2006 (sh), 1999
which were related to the atoms ridden upon. All other non-
hydrogen atoms were refined anisotropically.
(s), 1986 (m, br), 1943 (w), 1916 (w, br) cm-1 1H-NMR (CDCl3,
.
Scattering factors were taken from Cromer and Waber.17
Anomalous dispersion corrections were those of Cromer.18 All
data processing for 11 and 13 was carried out on a DEC Micro
VAXII using the MolEN programs and for 5 and 12 on a DEC
3000 AXP computer using the Open MolEN system of pro-
grams.19 Structure refinement and preparation of figures and
tables for publication were carried out on a DEC Micro VAXII
using MolEN for 11 and 13 and on PC’s using SHELXL-9316
and XP/PC20 programs for 5 and 12.
400 MHz) 4.04 (m, 1H), 3.07 (m, 1H), 2.91 (m, 2H), 2.33 (s,
3H), 2.15 (s, 3H), 2.09 (d, 3H), 2.05 (s, 3H), 1.95 (m, 1H), 1.76
(m, 1H), 1.75 (q, 1H) ppm.
X-r a y Str u ctu r e Deter m in a tion of 5, 11, 12, a n d 13.
Crystals of 5, 11, 12, a n d 13 for X-ray examination were
obtained from saturated solutions of each in hexane/dichlo-
romethane solvent systems at -20 °C. Suitable crystals of
each were mounted on glass fibers, placed in a goniometer
head on the Enraf-Nonius CAD4 diffractometer, and centered
optically. Unit cell parameters and an orientation matrix for
data collection were obtained by using the centering program
in the CAD4 system. Details of the crystal data are given in
Table 1. For each crystal, the actual scan range was calculated
by scan width ) scan range + 0.35 tan θ, and backgrounds
were measured by using the moving-crystal/moving-counter
technique at the beginning and end of each scan. Two
representative reflections were monitored every 2 h as a check
on instrument and crystal stability, and an additional two
reflections were monitored periodically for crystal orientation
control. Lorentz, polarization, and decay corrections were
applied, as was an empirical absorption correction based on a
series of ψ scans for each crystal. The weighting scheme used
during refinement for all structures was 1/σ2.
Ack n ow led gm en t. We gratefully acknowledge the
support of the National Science Foundation
(CHE9319062 and 9624367, E.R.), Consiglio Nazionale
delle Ricerche (L.M.), the Ministry of University and
Scientific Research (L.M.), the University of Montana
(E.R.), and the Universita` di Torino (E.R.) for support
of this research.
Su p p or tin g In for m a tion Ava ila ble: Complete distances
and bond angles, anisotropic thermal parameters, and atomic
coordinates, (Tables 6-19) for 5, 11, 12, and 13 (28 pages).
Ordering information is given on any current masthead page.
OM9610915
Each of the structures was solved by the Patterson method
using SHELXS-86,15 which revealed the positions of the metal
atoms. All other non-hydrogen atoms were found by successive
difference Fourier syntheses. Hydrogen atoms were included
for each structure, placed in their expected chemical positions
using the HFIX command in SHELXL-93,16 and included as
riding atoms in the final least squares refinements with U’s
(16) Sheldrick, G. M. Program for Structure Refinement; University
of Goettingen: Goettingen, Germany, 1993.
(17) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystasllography; Kynoch: Birmingham, 1974; Vol. 4, Table 2.2B.
(18) Cromer, D. T. International Tables for X-ray Crystallography;
Kynoch: Birmingham, 1974; Vol. 4, Table 2.3.1.
(19) Fair, C. Kay, “MolEN” Structure Determination System; Enraf-
Nonius: Delft, The Netherlands, 1990.
(20) “XP/ PC” Molecular Graphics Software; Siemans Analytical
X-ray Instruments, Inc.: Madison, WI.
(15) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.