Synthesis, structure, and transformation of novel osmium azine and ylide complexes

Article abstract of DOI:10.1021/ic050431o

Three novel triosmium complexes with unusual coordination characteristics are reported. Treatment of the hydridotriosmium cluster (μ-H) ₂Os₃(CO)₁₀ with CNNPPh₃ in CH ₂Cl₂ gave complexes (μ-H)Os₃(CO) ₁₀(μ₂-η²-C(H)-NNPPh₃) (1) and (μ-H)Os₃(CO)₁₀(μ₂-η¹- CHPPh₃) (2). Complex 1 represents the first example of the existence of a coordinated phosphinazine ligand. An in-situ ¹H NMR study showed that the reaction of (μ-H)₂Os₃(CO)₁₀ with CNNPPh₃ produced complex 1 as the initial product in 100% conversion. The latter is not stable in solution and slowly eliminates nitrogen to form an unusual ylide complex 2 in quantitative yield. The thermolysis of 2 in refluxing toluene afforded (μ-H)₃Os₃(CO) ₉(μ₃-η¹-CCO₂CH₂Ph) (3) as a colorless compound. Complexes 1-3 were characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. The interesting feature of structure 3 is the presence of a μ₃-alkylidyne ligand where the symmetrically triply bridged CCO₂CH₂Ph fragment lies perpendicular to and above the triosmium triangle.

Full text of DOI:10.1021/ic050431o

Inorg. Chem. 2005, 44, 6425−6430
Synthesis, Structure, and Transformation of Novel Osmium Azine and
Ylide Complexes
Te-Wei Chiu,†,‡ Yen-Hsiang Liu,† Kai-Ming Chi,‡ Yuh-Sheng Wen,† and Kuang-Lieh Lu*,†
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, and Department of Chemistry and
Biochemistry, National Chung Cheng UniVersity, Chiayi 62, Taiwan
Received March 23, 2005
Three novel triosmium complexes with unusual coordination characteristics are reported. Treatment of the
hydridotriosmium cluster ( -H)2Os3(CO)10 with CNNPPh3 in CH2Cl2 gave complexes ( -H)Os3(CO)10
2-C(H)-
NNPPh3) (1) and ( -H)Os3(CO)10
1-CHPPh3) (2). Complex 1 represents the first example of the existence of
a coordinated phosphinazine ligand. An in-situ 1H NMR study showed that the reaction of (
-H)2Os3(CO)10 with
µ
µ
(µ2-η
µ
(µ2-η
µ
CNNPPh3 produced complex 1 as the initial product in 100% conversion. The latter is not stable in solution and
slowly eliminates nitrogen to form an unusual ylide complex 2 in quantitative yield. The thermolysis of 2 in refluxing
toluene afforded (
by spectroscopic methods and single-crystal X-ray diffraction analysis. The interesting feature of structure 3 is the
presence of a 3-alkylidyne ligand where the symmetrically triply bridged CCO2CH2Ph fragment lies perpendicular
to and above the triosmium triangle.
µ-H)3Os3(CO)9(µ3-η −3 were characterized
1-CCO2CH2Ph) (3) as a colorless compound. Complexes 1
µ
Introduction
chemistry.2 N-Isocyanoiminetriphenylphosphorane (CNNP-
Ph3) is a versatile ligand, which easily substitutes for a more
labile ligand to afford metal N-isocyanide complexes and
also undergoes nucleophilic or electrophilic reactions.3 Upon
coordination to the metal, the CNNPPh3 moiety has been
reported to further undergo Wittig-type reactions with
ketones and aldehydes in the presence of a catalytic amount
of acid to form N-isocyanoimine analogues.4-7 Although
CNNPPh3 has been known for many years, only a few related
studies concerning its organometallic chemistry have ap-
peared in the literature.3-5 In the course of our continuing
Trinuclear osmium complexes have been extensively used
as model compounds because of their relative stability.1,2
Many osmium-containing intermediates have been isolated
and characterized, thus providing a better understanding of
many fundamental reactions involved in organometallic
* To whom correspondence should be addressed. E-mail: lu@
chem.sinica.edu.tw.
† Academia Sinica.
‡ National Chung Cheng University.
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10.1021/ic050431o CCC: $30.25
Published on Web 08/04/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 18, 2005 6425

Chiu et al.
studies on the chemistry of metal isocyanide complexes,4,8,9
we have been interested in the reactivity of CNNPPh3-
containing complexes to try to understand the mediation
effect of the metal centers on the property of this coordinated
ligand.5,10 Herein we report on the synthesis and transforma-
tion of three unprecedented triosmium complexes containing
unusual ligands derived from the reaction of CNNPPh3 with
the hydridotriosmium complex H2Os3(CO)10. Their coordina-
tion modes are reported here for the first time.
Results and Discussion
Reaction of H2Os3(CO)10 with CNNPPh3. The purple
hydridotriosmium cluster H2Os3(CO)10 was prepared by
bubbling hydrogen into a solution of Os3(CO)12 in refluxing
n-octane over a 2 h period.11 The H2Os3(CO)10 produced was
then dissolved in CH2Cl2 and treated with CNNPPh3 at room
temperature to afford a yellow complex, (µ-H)Os3(CO)10-
(µ2-η2-C(H)NNPPh3) (1), and a small amount of an orange
complex, (µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2, eq 1).
Figure 1. ORTEP diagram of (µ-H)Os3(CO)10(µ2-η2-C(H)NNPPh3) (1).
indicate the reaction involves the insertion of an isocyanide
into the metal-hydride bond.12
An X-ray structure analysis of 1 was undertaken to
investigate the exact coordination characteristics of the
CNNPPh3 ligand within the cluster. An ORTEP drawing of
1 is shown in Figure 1, and relevant crystallographic data
are given in Tables 1 and 2. The three Os atoms define an
isosceles triangle with one elongated edge (Os(2)-Os(3) )
2.923(2) Å) and two shorter edges (Os(1)-Os(2) ) 2.868-
(1) Å and Os(1)-Os(3) ) 2.873(2) Å). The C(11) and N(1)
atoms of the C(H)NNPPh3 moiety coordinate at two axial
sites of the Os(2)-Os(3) vector forming a µ2-η2-edge-bridged
phosphinazine moiety. The Os(2), Os(3), N(1), and C(11)
atoms are nearly coplanar. The plane defined by these four
atoms is nearly orthogonal to that defined by the triosmium
atoms. The C(11)-N(1) forms a double bond (1.28(1) Å),
and N(1)-N(2) forms a single bond (1.42(1) Å).13 A partial
double-bond character exists between N(2)-P(1) with a
distance of 1.596(7) Å.13
An in-situ 1H NMR study showed that the reaction of (µ-
H)2Os3(CO)10 with CNNPPh3 produced complex 1 as the
initial product in 100% conversion. The proposed pathway
for the formation of complex 1 is shown in eq 1. Adams
and co-workers observed that the reaction of hydridotrios-
mium cluster with an isocyanide ligand (CNR) forms adducts
of the type H2Os3(CO)10(CNR) (R ) C6H5, Me, But).12a,b
Although we were unable to detect any reaction intermedi-
ates, we propose that the hydridotriosmium cluster reacts with
CNNPPh3 initially forming H2Os3(CO)10(CNNPPh3), and this
reaction is followed by the insertion of isocyanide into the
metal hydride to afford complex 1. Other related triosmium
The FAB mass spectrum of 1 showed a molecular ion peak
at m/z 1161, which corresponds to an adduct of H2Os(CO)10
and CNNPPh3. The H NMR spectrum of 1 showed a
1
bridging hydride peak at δ -15.49 ppm, phenyl proton
signals in the δ 7.47-7.58 ppm region, and another proton
signal at δ 8.82 ppm. In the 31P{1H} NMR spectrum, the
triphenyl phosphine group gave rise to a singlet at δ 8.09
ppm, demonstrating that the CNNPPh3 is not coordinated to
the osmium cluster in the terminal mode. [cf. the terminal
CNNPPh3 ligands in complexes ReBr(CO)3(CNPh)(CNNPPh3)
and ReBr(CO)3(CNPr)(CNNPPh3) resonate at δ 32.36 and
1
32.14, respectively].5 The heteronuclear H-13C (HMQC)
spectrum showed that the proton at δ 8.82 was bound to the
carbon atom (CNNPPh3) at δ 155.5 ppm. These findings
(8) (a) Lu, K. L.; Chen, C. C.; Lin, Y. W.; Gau, H. M.; Hong, F. E.;
Wen, Y. S. Organometallics 1993, 12, 2188. (b) Lu, K. L.; Chung,
M. L.; Lu, P. Y.; Gau, H. M.; Hong, F. E.; Wen, Y. S. Organometallics
1994, 13, 3177. (c) Huang, J. Y.; Lin, K. J.; Chi, K. M.; Lu, K. L. J.
Chem. Soc., Dalton Trans. 1997, 15.
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1994, 13, 593. (b) Fan, J. S.; Lin, J. T.; Chang, C. C.; Chou, S. J.; Lu,
K. L. Organometallics 1995, 14, 925. (c) Lee, F. Y.; Huang, J. J.;
Chen, Y. J.; Lin, K. J.; Lee, G. H.; Peng, S. M.; Hwu, J. R.; Lu, K.
L. J. Organomet. Chem. 2005, 690, 441.
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2579. (b) Adams, R. D.; Golembeski, N. M. Inorg. Chem. 1979, 18,
1909. (c) Tanase, T.; Ohizumi, T.; Kobayashi, K.; Yamamoto, Y.
Organometallics 1996, 15, 3404. (d) Antinolo, A.; Carrillo-Hermosilla,
F.; Fajardo, M.; Garcia-Yuste, S.; Otero, A.; Camanyes, S.; Maseras,
F.; Moreno, M.; Lledos, A.; Lluch, J. M. J. Am. Chem. Soc. 1997,
119, 6107. (e) Visser, C.; van den Hende, J. R.; Meetsma, A.; Hessen,
B.; Teuben, J. H. Organometallics 2001, 20, 1620. (f) Guan, H.;
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2003, 22, 4084.
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Chem. Soc. 1975, 97, 3942.
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G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
6426 Inorganic Chemistry, Vol. 44, No. 18, 2005

NoWel Osmium Azine and Ylide Complexes
Table 1. Crystal Data and Refinement of
(µ-H)Os3(CO)10(µ2-η2-C(H)NNPPh3) (1),
(µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2), and (µ-H)
3Os3(CO)9(µ3-η1-CCO2CH2Ph) (3)
C29H17N2O10Os3P C29H17O10Os3P C36H20O22Os6
fw
T, K
wavelength, Å
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
1155.00
293(2)
0.71073
monoclinic
C2/c
32.61(2)
13.157(2)
17.719(9)
90
121.83(3)
90
6458(5)
8
1127.00
293(2)
0.71073
triclinic
P1h
9.174(2)
11.905(2)
15.000(5)
84.56(2)
91.84(2)
107.60(1)
1554.6(6)
2
1945.67
293(2)
0. 71073
triclinic
P1h
8.287(2)
14.998(3)
18.674(4)
90.10(2)
96.73(2)
98.32(2)
2280.3(9)
2
Z
D
calcd, g cm-3
2.372
2.408
12.335
1028
2.825
16.729
1724
µ(Mo KR), mm-1 11.882
F(000)
4208
Figure 2. ORTEP diagram of (µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2).
cryst size, mm
no. measured reflns 5686
0.24, 0.21, 0.14
0.26, 0.22, 0.14 0.19, 0.38, 0.41
5837
8621
no. unique reflns
no. obsd reflns
R1a [I > 2σ(I)]
wR2a [all data]
GOF
5686
4150
0.0361
0.0861
1.055
5461
3766
0.0419
0.1217
1.047
8013
5735
0.0551
0.1694
1.013
complexes containing a CdN moiety are well-known in the
literature, dating as far back as the works of Deeming and
Adams in the late 1970s and early 1980s.14,15 More recently,
Rosenberg and co-workers reported the synthesis and
transformation of a number of imidoyl-bridged triosmium
clusters.16 In comparison with those triosmium complexes
containing the CdN moiety, the coordinated phosphinazine
ligand in complex 1 is observed for the first time.
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2 ) {∑[w(Fo2 - Fc2)2]/∑|Fo|[w(Fo ) ]}1/2
.
2 2
Table 2. Selected Bond Distances (Å) and Angles (deg) for
(µ-H)Os3(CO)10(µ2-η2-C(H)NNPPh3) (1)
Bond Distances
Spectroscopic Characterization and Crystal Structure
of Complex 2. The FAB mass spectrum of 2 showed a
molecular ion peak at m/z 1133, with 28 fewer mass units
compared to that of complex 1. Hence, complex 1 was
converted into complex 2 by the elimination of either a CO
ligand or a N2 molecule. The 1H NMR spectrum of complex
2 showed a bridging hydride as a double-doublet centered
at δ -16.67 ppm, another double-doublet resonance at δ 4.70
ppm integrating as one proton, and phenyl protons at δ 7.44-
7.64. The triphenylphosphine group gives rise to a resonance
at 47.77 ppm in the 31P spectrum. A single crystal of 2 was
obtained by recrystallization from chloroform. An ORTEP
drawing from the X-ray analysis of complex 2 is shown in
Figure 2, and the derived bond distances and angles are
summarized in Table 3. The structure of 2 consists of a
triangle of osmium atoms with one shorter edge (Os(2)-
Os(3) ) 2.811(1) Å) and two longer edges (Os(1)-Os(2) )
2.868(1) Å and Os(1)-Os(3) ) 2.871(1) Å). An unidentified
bridging atom, either a carbon or a nitrogen, is coordinated
to two axial sites of the Os(2)-Os(3) vector. The X-ray
structure could not fully differentiate whether this unidenti-
fied atom is a carbon or a nitrogen atom. However, an
elemental analysis of complex 2 showed the conspicuous
absence of nitrogen. The 13C NMR spectrum of 2 is
consistent with this unidentified bridging atom being a
Os1-Os2
Os1-Os3
Os1-C1
Os1-C2
Os1-C3
Os1-C4
Os2-Os3
Os2-C5
Os2-C6
Os2-C7
Os2-C11
2.868(1)
2.873(2)
1.92(1)
1.91(1)
1.94(1)
1.93(1)
2.923(2)
1.87(1)
1.88(1)
1.95(1)
2.097(9)
Os3-N1
Os3-C8
Os3-C9
Os3-C10
P1-N2
P1-C21
P1-C31
P1-C41
N1-N2
N1-C11
2.098(6)
1.93(1)
1.90(1)
1.90(1)
1.596(7)
1.818(9)
1.812(9)
1.800(9)
1.417(9)
1.28(1)
Bond Angles
61.20(3)
Os2-Os1-Os3
Os1-Os2-Os3
Os1-Os2-C5
Os1-Os2-C11
Os3-Os2-C11
C5-Os2-C11
C6-Os2-C11
C7-Os2-C11
Os1-Os3-Os2
Os1-Os3-N1
Os2-Os3-N1
Os2-C11-N1
Os2-Os3-C10
N1-Os3-C8
N1-Os3-C9
N1-Os3-C10
Os3-N1-N2
Os3-N1-C11
N2-N1-C11
P1-N2-N1
114.0(6)
107.6(3)
87.5(3)
59.47(4)
173.2(3)
88.5(2)
66.4(2)
84.9(4)
92.8(4)
171.8(4)
59.33(4)
90.8(2)
67.3(2)
92.5(3)
174.1(4)
120.7(5)
112.0(6)
127.2(7)
118.2(5)
114.1(4)
N2-P1-C21
carbon, the chemical shift of which is δ -1.20 ppm, with a
coupling constant of JCP ) 25.2 Hz, indicating that carbon
was bound to a PPh3 group. The 1H-13C (HMQC) spectrum
also indicated that this carbon was also bound to a proton,
1
which resonated at δ 4.70 ppm. The H NMR spectrum
further confirmed the existence of this C-H bond, since this
proton signal appeared as a double-doublet as the result of
coupling with both the PPh3 group (JHP ) 6.9 Hz) and the
bridging hydride (JHH ) 4.2 Hz). This conclusion was
confirmed by the heteronuclear 1H-15N (HMQC) spectrum,
which shows no cross signals. These results indicate that
complex 2 contains a unique phosphine-stabilized µ2-
alkylidyne C(H)(PPh3) moiety, which is zwitterionic in
(14) Yin, C. C.; Deeming, A. J. J. Organomet. Chem. 1977, 133, 123.
(15) Adams, R. D.; Katahira, D. A.; Yang, L. W. J. Organomet. Chem.
1981, 219, 85.
(16) (a) Day, M.; Espitia, D.; Hardcastle, K. I.; Kabir, S. E.; Rosenberg,
E.; Gobetto, R.; Milone, L.; Osella, D. Organometallics 1991, 10, 3550.
(b) Kabir, S. E.; Rosenberg, E.; Day, M.; Hardcastle, K. I.; Irving, M.
J. Cluster Sci. 1994, 5, 481. (c) Kabir, S. E.; Rosenberg, E.; Stetson,
J.; Yin, M.; Ciurash, J.; Mnatsakanova, K.; Hardcastle, K. I.; Noorani,
H.; Movsesian, N. Organometallics 1996, 15, 4473.
Inorganic Chemistry, Vol. 44, No. 18, 2005 6427

Chiu et al.
Table 3. Selected Bond Distances (Å) and Angles (deg) for
(µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2)
Bond Distances
Os1-Os2
Os2-Os3
Os3-Os1
Os2-C40
Os3-C40
Os2-C5
Os2-C6
Os2-C7
Os3-C8
Os3-C9
Os3-C10
2.868(1)
2.811(1)
2.871(1)
2.17(1)
2.15(1)
1.87(1)
1.95(2)
1.89(2)
1.86(2)
1.91(1)
1.91(2)
Os1-C1
Os1-C2
Os1-C3
Os1-C4
C5-O5
C6-O6
C7-O7
C9-O9
C10-O10
C40-P
1.93(2)
1.94(2)
1.88(2)
1.89(2)
1.15(2)
1.11(2)
1.12(2)
1.13(2)
1.14(2)
1.75(1)
Bond Angles
80.8(5)
123.2(8)
129.3(9)
84.6(3)
85.0(3)
Os(2)-C(40) -Os(3)
Os(2)-C(40)-P
Os(2)-Os(1)-Os(3)
C(9)-Os(3)-C(40)
C(6)-Os(2)-C(40)
Os(1)-Os(2)-C(7)
Os(1)-Os(3)-C(10)
58.64(2)
168.9(5)
165.5(5)
175.9(4)
176.6(4)
Os(3)-C(40)-P
Figure 3. ORTEP diagram of (µ-H)3Os3(CO)9(µ3-η1-CCO2CH2Ph) (3).
Os(1)-Os(2)-C(40)
Os(1)-Os(3)-C(40)
Table 4. Selected Bond Distances (Å) and Angles (deg) of
(µ-H)3Os3(CO)10(µ-CCO2CH2Ph) (3)
nature. The P-C(40) distance (1.75(1) Å) is shorter than
the lengths of the P-CH3 single bond (1.83(3) and 1.84(2)
Å) in two ylide complexes.13,17,18 There are many phosphine-
stabilized zwitterionic hydrocarbyl ligands in the litera-
ture.19,20 The structure of 2 resembles that of the methylene
cluster (µ-H)(µ-CH2)Os3(CO)10.21
Bond Distances
Os(1)-Os(2)
Os(2)-Os(3)
Os(3)-Os(1)
Os(1)-C(10)
Os(2)-C(10)
Os(3)-C(10)
C(10)-C(11)
C(11)-O(11)
C(11)-O(12)
C(12)-O(12)
2.876(1)
2.874(1)
2.890(1)
2.07(2)
2.09(2)
2.10(2)
1.44(2)
1.22(2)
1.36(2)
1.48(2)
Os(1)-C(1)
Os(1)-C(2)
Os(1)-C(3)
Os(2)-C(4)
Os(2)-C(5)
C(6)-O(6)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(12)-C(13)
1.92(2)
1.91(2)
1.98(2)
1.91(2)
1.94(2)
1.11(2)
1.13(2)
1.14(2)
1.12(2)
1.46(3)
The conversion of 1 to 2 occurred when a CDCl3 solution
of 1 was allowed to stand at room temperature, indicating
that complex 1 is a reaction intermediate (eq 1). When
complex 1 was heated in CDCl3 at 40 °C and the progress
of the reaction monitored by 1H NMR spectroscopy,22
complex 1 was converted to 2 in quantitative yield. The rate
of this transformation obeys the first-order rate law, and the
linear least-squares fits of log[1] versus time were used to
obtain the rate constants at three different temperatures (40-
55 °C). The first-order rate constants in CDCl3 at 40, 50,
and 55 °C are 3.95 × 10-5, 1.74 × 10-4, and 3.09 × 10-4
s-1, respectively. The activation energy, Ea, calculated from
the Arrhenius plot is 28.1 kcal/mol. The key step of this
transformation appears to involve the elimination of nitrogen
to form the highly stabilized coordinated ylide moiety.
Reactivity of Complex 2. The thermolysis of 2 was
carried out in refluxing toluene under nitrogen for 12 h. The
1H NMR spectrum of the crude products indicated the
presence of a number of species with hydride peaks at δ
Bond Angles
60.33(3) Os(2)-Os(1)-Os(3)
59.87(3) Os(1)-C(10)-Os(3)
Os(1)-Os(2)-Os(3)
Os(1)-Os(3)-Os(2)
Os(1)-C(10)-Os(2)
59.80(3)
87.7(7)
129(1)
87.5(6)
Os(1)-C(10)-C(11)
C(11)-O(12)-C(12) 117(2)
C(10)-C(11)-O(11) 126(2)
-12.07, -12.58, -12.72, -13.73, -14.96, -15.15, -19.37,
-19.42 (major), and -19.83 ppm, demonstrating the com-
plexity of the reaction. Chromatographic workup of the
product permitted the isolation of a low yield of a colorless
compound (µ-H)3Os3(CO)9(µ3-η1-CCO2CH2Ph) (3) and some
other unidentified byproducts (eq 2). The IR spectrum of 3
showed only two peaks in the CtO stretching region
indicating that the structure of this compound most likely is
highly symmetrical.
(17) Vicente, J.; Chicote, M. T.; Cayuelas, J. A.; Fernandez-Baeza, J.; Jones,
P. G.; Sheldrick, G. M.; Espinet, P. J. Chem, Soc., Dalton Trans. 1985,
1163.
(18) (a) Cramer, R. E.; Maynard, R. B.; Paw, J. C.; Gilje, J. W.
Organometallics 1983, 2, 1336. (b) Fuchs, A.; Gudat, D.; Nieger, M.;
Schmidt, O.; Sebastian, M.; Nyulaszi, L.; Niecke, E. Chem. Eur. J.
2002, 8, 2188. (c) Falvello, L. R.; Llusar, R.; Margalejo, M. E.;
Navarro, R.; Urriolabeitia, E. P. Organometallics 2003, 22, 1132.
(19) (a) Cherkas, A. A.; Doherty, S.; Cleroux, M.; Hogarth, G.; Randall,
L. H.; Breckenridge, S. M.; Taylor, N. J.; Carty, A. J. Organometallics
1992, 11, 1701. (b) Mott, G. N.; Carty, A. J. Inorg. Chem. 1983, 22,
2726.
(20) (a) Sanctis, Y. D.; Arce, A. J.; Ganavera, F.; Machado, R.; Deeming,
A. J.; Gonzalez, T.; Galarza, E. J. Organomet. Chem. 2004, 689, 2025.
(b) Arce, A. J.; Machado, R.; Sanctis, Y. D.; Capparelli, M. V.;
Atencio, R.; Manzur, J.; Deeming, A. J. Organometallics 1997, 16,
1735.
Although the 31P NMR spectrum of 3 showed no resonance
signals, surprisingly, its 1H NMR spectrum showed aromatic
protons at δ 7.43-7.24 ppm. The molecular structure of this
compound was verified by an X-ray crystallographic method.
An ORTEP diagram of 3 is shown in Figure 3, and the
derived bond distances and angles are summarized in Table
4. The striking feature of the structure is the presence of a
µ3-alkylidyne ligand where the symmetrically triply bridged
CCO2CH2Ph fragment is lying perpendicular to and above
the triosmium triangle. The Os-C distances are as follows:
(21) Schultz, A. J.; Williams, J. M.; Calvert, R. B.; Shapley, J. R.; Stucky,
G. D. Inorg. Chem. 1979, 18, 319.
(22) Uedelhoven, W.; Neugebauer, D.; Kreissl, F. R. J. Organomet. Chem.
1981, 217, 183.
6428 Inorganic Chemistry, Vol. 44, No. 18, 2005

NoWel Osmium Azine and Ylide Complexes
color of the solution became yellow. The solvent was removed
under vacuum, and the residue was chromatographed on a silica
gel TLC plate. Elution with CH2Cl2/hexane (50:50) afforded a
yellow compound (µ-H)Os3(CO)10(µ2-η2-C(H)NNPPh3) (1) in 59%
yield (75.4 mg, 0.065 mmol) and a small amount of an orange
complex (µ-H)Os3(CO)10(µ-CHPPh3) (2) in 6% yield (7.2 mg, 6.4
µmol). Anal. Calcd for C27H17N2O10POs3 (1): C, 30.16; H, 1.48;
N, 2.43. Found: C, 29.95; H, 1.82; N, 2.31. IR (CH2Cl2): ν(CO)
2101 (w), 2059 (s), 2048 (m), 2013 (vs), 1986 (m) cm-1. 1H NMR
(CDCl3): δ 8.82 (s, 1 H, CH), 7.50 (m, 15 H, Ph), -15.49 (s, 1 H,
Os-H-Os) ppm. 13C NMR (CDCl3): δ 184.58, 183.98, 179.08,
178.34, 175.94, 175.47 (2 CO), 175.01, 174.74, 174.39 (CO), 155.5
(d, JCP ) 17.1 Hz, µ-CHdN), 132.8 (Ph), 132.6 (d, JCP ) 10.5
Hz, Ph), 128.7 (d, JCP ) 11.5 Hz, Ph), 126.9 (d, JCP ) 93.5 Hz,
Cipso, Ph) ppm. 31P NMR (CDCl3): δ 8.09 ppm. Mass (FAB,
Os192): m/z 1161 (M+), 1133 (M+ - CO), 1105 (M+ - 2CO),
1077 (M+ - 3CO), 1049 (M+ - 4CO), 1021 (M+ - 5CO), 993
(M+ - 6CO), 965 (M+ - 7CO).
Os(1)-C(10) ) 2.07(2) Å, Os(2)-C(10) ) 2.09(2) Å, and
Os(3)-C(10) ) 2.10(2) Å. On the basis of IR, H NMR,
and mass analysis, there are three bridging hydrides appear-
ing in the structure.
1
The FAB mass spectrum of 3 showed a molecular ion peak
at m/z 974 and additional peaks at m/z 867, 838, 810, and
783 corresponding to the subsequent loss of one PhCH2O
fragment and three CO ligands. In solution, the free rotation
of C(10)-C(11) bond allows molecule 3 to attain a C3V
symmetry, which explains the IR spectrum of 3, which
contains only two peaks in the CO stretching region. Shapley
and Geoffroy reported that the thermally induced loss of
carbon monoxide from Os3(CO)10(µ-CO)(µ-CH2) occurs,
resulting in the formation of (µ-H)2Os3(CO)9(µ3-1,2-η2-
CCO).23 These two species might be the reaction intermedi-
ates when complex 2 eliminated a PPh3 group under refluxing
conditions in toluene. The structure of compound 3 shows
that two oxygen atoms are present in the triply bridged ligand
C-C(O)OCH2Ph. This suggests that when one of the
carbonyls of 2 is bent and then reacts further, the reaction
might eventually lead to the formation of compound 3 with
the triply bridged ligand C-C(O)OCH2Ph. However, the
origin of the second oxygen remains unclear. Presumably,
the formation of 3 requires a trace of water or O2, since either
of these could serve as the source of the second oxygen. At
this stage we are not able to provide details of the reaction
pathway. However, this reaction does produce an unprec-
edented complex with unusual coordination characteristics.
In summary, three novel triosmium complexes derived
directly or indirectly from the reaction of (µ-H)2Os3(CO)10
with CNNPPh3 were obtained. The products include the first
example of a coordinated phosphinazine ligand (in 1), a
phosphine-stabilized µ2-alkylidyne (2), and a µ3-alkylidyne
(3) formed via CO insertion, C-C coupling, and hydrogen
migration.
Preparation of (µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2). Hydrogen
was bubbled through a refluxing solution of Os3(CO)12 (150.6 mg,
0.166 mmol) in octane (130 mL) resulting in a color change from
yellow to deep red in 2 h. The solvent was removed under vacuum,
and the residue was dissolved in CHCl3 (80 mL), treated with
CNNPPh3 (50.4 mg 0.167 mmol) in CHCl3 (20 mL), and again
refluxed. The reaction was stopped when the IR pattern changed
in 2 h. The solvent was removed under vacuum, and the residue
was chromatographed on a silica gel TLC plate. Elution with CH2-
Cl2/hexane (50:50) afforded an orange complex (µ-H)Os3(CO)10-
(µ2-η1-CHPPh3) (2) in 55% yield (102.9 mg, 0.091 mmol). For 2:
Calcd for C29H17O10Os3P: C, 30.91; H, 1.52. Found: C, 30.88; H,
1.61. IR (CH2Cl2): ν(CO) 2089 (m), 2042 (vs), 2031 (m), 2003 (s),
1993 (s), 1956 (s) cm-1.1H NMR (CDCl3): δ 7.44-7.64 (m, 15
H, Ph), 4.70 (dd, 1 H, CH, JHP ) 6.9 Hz, JHH ) 4.2 Hz), -16.67
(dd, 1 H, Os-H-Os, JHH ) 4.2 Hz, JHP ) 1.0 Hz) ppm. 13C NMR
(CDCl3): δ 189.2, 183.5, 177.8, 177.7, 177.3 (2CO), 176.6 (2CO),
173.9 (2CO), 134.0, 133.8, 133.1, 132.8, 129.6, 129.1, 129.0 (Ph),
-1.20 (d, JCP ) 25.2 Hz, µ-CHP) ppm. 31P NMR (CDCl3): δ 47.77
ppm. Mass (FAB, Os192): m/z 1133 (M+), 1105 (M+ - CO), 1077
(M+ - 2CO), 1049 (M+ - 3CO), 1021 (M+ - 4CO).
1
In-Situ H NMR Study on the Transformation of 1 to 2. A
Experimental Section
solution of (µ-H)2Os3(CO)10 (25 mg, 0.029 mmol) in CDCl3 (0.4
mL) in an NMR tube was treated with CNNPPh3 (8.8 mg, 0.029
mmol) in CDCl3 (0.2 mL). The reaction was monitored by 1H NMR
spectroscopy at 313, 323, and 328 K. The spectral data showed
that the complex (µ-H)Os3(CO)10(µ2-η2-C(H)NNPPh3) (1) was
produced as the initial product, and then was slowly converted to
(µ-H)Os3(CO)10(µ2-η2-CHPPh3) (2) in quantitative yield.
Thermolysis of (µ-H)Os3(CO)10(µ2-η2-CHPPh3) (2). A solution
of (µ-H)Os3(CO)10(µ2-η2-CHPPh3) (2) (100 mg, 0.0887 mmol) in
toluene (80 mL) was refluxed for 12 h, at which time the IR
spectrum showed the disappearance of the characteristic bands of
the precursor. The reaction was stopped, and the solvent was
removed under vacuum. The 1H NMR spectrum of the crude
products indicated the presence of a number of species with hydride
peaks at δ -12.07, -12.58, -12.72, -13.73, -14.96, -15.15,
-19.37, -19.42 (major), and -19.83 ppm, demonstrating the
complexity of the reaction. The residue was chromatographed on
a silica gel TLC plate. Elution with CH2Cl2/hexane (50:50) afforded
colorless compound (µ-H)3Os3(CO)9(µ3-η1-CCO2CH2Ph) (3) in
9.3% yield (8 mg, 8.21 µmol). Several unidentified species (-12.58,
-12.72, -14.96, -19.37 ppm) are eluted very close to compound
3. Special care was thus taken to isolate the band corresponding to
complex 3. We were not able to assign the other peaks because of
General Data. The ligand CNNPPh3 was prepared by a
previously reported method.3 Other reagents were purchased from
commercial sources and were used as received. All manipulations
were performed with standard Schlenk techniques. Solvents were
dried by stirring over Na/benzophenone (n-octane) or CaH2 (hexane,
CH2Cl2, CHCl3) and were freshly distilled prior to use. Infrared
spectra were recorded on a Perkin-Elmer PARAGON 1000 FT-IR
spectrometer. NMR spectra were obtained on a Bruker ACP-300
or an AMX-500 FT-NMR spectrometer. Elemental analyses were
performed by means of a Perkin-Elmer 2400 CHN elemental
analyzer.
Reaction of H2Os3(CO)10 with CNNPPh3. Bubbling hydrogen
through a refluxing solution of Os3(CO)12 (100.3 mg, 0.110 mmol)
in n-octane (100 mL) resulted in a color change from yellow to
deep red in 2 h. The solvent was removed under vacuum, and the
residue was dissolved in CH2Cl2 (80 mL) and treated with a solution
of CNNPPh3 (36.3 mg 0.120 mmol) in CH2Cl2 (20 mL) at room
temperature. The reaction was complete within seconds, and the
(23) (a) Sievert, A. C.; Srickland, D. S.; Shapley, J. R.; Steinmentz, G. R.;
Geoffroy, G. L. Organometallics 1982, 1, 214. (b) Shapley, J. R.;
Srickland, D. S.; St. George, G. N.; Churchill, M. R.; Bueno, C.
Organometallics 1983, 2, 185.
Inorganic Chemistry, Vol. 44, No. 18, 2005 6429

Chiu et al.
serious overlapping and the complexity of the spectrum. IR (CH2-
empirical absorption corrections were applied the data for these
structures. The structures of 1, 2, and 3 were solved by direct
methods and refined against F2 by the full-matrix least-squares
technique, using the WINGX24 and SHELX25 software packages.
1
Cl2): ν(CO) 2087 (s), 2026 (vs), 1668 (s, ester) cm-1. H NMR
(CDCl3): δ 7.43-7.24 (m, 5H, Ph), 5.27 (s, 2H, OCH2Ph), -19.42
(s, 3H, Os-H-Os) ppm. Mass (FAB, Os192): m/z 978 (M+), 871
(M+ - OCH2Ph), 843 (M+ - OCH2Ph - CO), 815 (M+ - OCH2-
Ph - 2CO), 787 (M+ - OCH2Ph - 3CO).
Acknowledgment. We thank Academia Sinica and the
National Science Council of Taiwan for financial support.
Crystallographic Analysis. Crystals of (µ-H)Os3(CO)10(µ2-η2-
CHNNPPh3) (1) and (µ-H)Os3(CO)10(µ2-η1-CHPPh3) (2) were
grown from a mixture of CH2Cl2 and hexane solutions at -20 °C.
Specimens of suitable quality were mounted in a thin-walled glass
capillary and used for measurement of precise cell constants and
intensity data collection. Diffraction measurements were made on
an Enraf-Nonius CAD-4 diffractometer using graphite-monochro-
matized Mo KR radiation (λ ) 0.71073 Å) with ω-2θ scan mode.
Unit cells were determined and refined using 25 randomly selected
reflections obtained using the CAD-4 automatic search, center,
index, and least-squares routines. Lorentz/polarization (LP) and
Supporting Information Available: Crystallographic files for
compounds 1-3 in CIF format. 1H NMR spectra showing the
transformation of 1 into 2. This material is available free of charge
via the Internet at http://pubs.acs.org.
IC050431O
(24) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(25) Sheldrick, G. M. SHELX-97 (including SHELXS and SHELXL);
University of Gottingen: Gottingen, Germany, 1997.
6430 Inorganic Chemistry, Vol. 44, No. 18, 2005