Reactivity of diynes with a 1-azavinylidene-bridged triruthenium carbonyl cluster. Insertion reactions of diynes into Ru-H, Ru-C, and Ru-N bonds

Article abstract of DOI:10.1021/om0005506

The reactivity of the 1-azavinylidene cluster complex [Ru₃(μ-H)(μ-N=CPh₂)(CO)₁₀] (1) with diynes has been studied. The nonconjugated diyne 1-trimethylsilyl-1,4-pentadiyne affords the binuclear ynenyl derivative [Ru₂(μ-N=CPh₂)(μ-η²-CH ₂=CCH₂C=CSiMe₃)(CO)₆] (2), which results from cluster fragmentation and from the insertion of the terminal alkyne fragment of the diyne into a Ru-H bond.

Full text of DOI:10.1021/om0005506

5424
Organometallics 2000, 19, 5424-5430
Rea ctivity of Diyn es w ith a 1-Aza vin ylid en e-Br id ged
Tr ir u th en iu m Ca r bon yl Clu ster . In ser tion Rea ction s of
Diyn es in to Ru -H, Ru -C, a n d Ru -N Bon d s
J avier A. Cabeza,*,† Fabrizia Grepioni,*,‡ Marta Moreno,† and V´ıctor Riera†
Departamento de Quı´mica Orga´nica e Inorga´nica, Instituto de Qu´ımica Organometa´lica
“Enrique Moles”, Universidad de Oviedo-CSIC, E-33071 Oviedo, Spain, and Dipartimento di
Chimica, Universita´ di Sassari, Via Vienna 2, I-07100 Sassari, Italy
Received J une 26, 2000
The reactivity of the 1-azavinylidene cluster complex [Ru3(µ-H)(µ-NdCPh2)(CO)10] (1) with
diynes has been studied. The nonconjugated diyne 1-trimethylsilyl-1,4-pentadiyne affords
the binuclear ynenyl derivative [Ru2(µ-NdCPh2)(µ-η2-CH2dCCH2CtCSiMe3)(CO)6] (2), which
results from cluster fragmentation and from the insertion of the terminal alkyne fragment
of the diyne into a Ru-H bond. The reactions of 1 with the internal conjugated diynes 1,6-
diphenoxy-2,4-hexadiyne, 2,4-hexadiyne, and diphenylbutadiyne have allowed the isolation
of the trinuclear derivatives [Ru3{µ-η2-NdCPh(C6H4)}(µ3-η4-PhOCH2CHdCdCdCHCH2OPh)-
(CO)8] (3), [Ru3{µ3-η4-NdCPh(C6H4)CH(Me)CHdCdCMe}(CO)9] (4), [Ru3{µ-η2-NdCPh-
(C6H4)}(µ3-η4-PhCHdCHCtCPh)(CO)8] (5), and [Ru3{µ3-η4-PhCHCHdC(CPh)NdCPh(C6H4)}-
(CO)9] (6). The four compounds have been characterized by X-ray diffraction methods. They
all arise from the orthometalation of a phenyl ring of the 1-azavinylidene ligand and from
the transfer of two hydride ligands (the original plus that coming from the orthometalation)
to the coordinated diyne. This hydrogenation process can proceed as a 1,4-addition to give
a 1,2,3-triene fragment (as occurs in 3) or as a 1,2-addition to give an enyne fragment (as
occurs in 5). In the cases of 4 and 6, a 1,2-addition of hydrogen is accompanied by the insertion
of the unsaturated hydrocarbon fragment into the Ru-C bond associated with the
orthometalated ring (4, 6) and into a Ru-N bond (6). The precise order by which these
processes lead to the corresponding products has not been established. The reactions involved
in the formation of compounds 2-6 represent excellent examples of insertion of diynes into
M-H, M-C, and M-N bonds of metal clusters and have allowed the characterization of
substituted 1-yn-3-enyl (in 2), 1,2,3-triene (in 3), 1,2-dienyl (in 4), 1-en-3-yne (in 5), and
2-(N-imido)-1,2,3-allyl-1-yl (in 6) ligands.
In tr od u ction
pound that contains a bridging amido ligand derived
from benzophenone imine, which can be regarded as a
1-azavinylidene ligand.10 As part of a general study of
the reactivity of compound 1,5-7,11 we have previously
reported that the thermal reaction of 1 with an excess
of diphenylacetylene results in the formation of the
The past decade has been witness to an increasing
interest in the synthesis and reactivity of late-transi-
tion-metal amido complexes as a consequence of the
relative scarcity of such compounds1-5 and of their
potential use in C-N bond-forming reactions.6-9
In this field, we have recently described a high-yield
synthesis of [Ru3(µ-H)(µ-NdCPh2)(CO)10] (1),5 a com-
(4) (a) Cabeza, J . A.; Riera, V.; Pellinghelli, M. A.; Tiripicchio, A. J .
Organomet. Chem. 1989, 376, C23. (b) Andreu, P. L.; Cabeza, J . A.;
Riera, V.; J eannin, Y.; Miguel, D. J . Chem. Soc., Dalton Trans. 1990,
2201. (c) Lugan, N.; Laurent, F.; Lavigne, G.; Newcomb, T. P.; Liimatta,
E. W.; Bonnet, J . J . Organometallics 1992, 11, 1351.
(5) Andreu, P. L.; Cabeza, J . A.; del R´ıo, I.; Riera, V.; Bois, C.
Organometallics 1996, 15, 3004.
(6) Cabeza, J . A.; del R´ıo, I.; Franco, R. J .; Grepioni, F.; Riera, V.
Organometallics 1997, 16, 2763.
(7) Cabeza, J . A.; del R´ıo, I.; Moreno, M.; Riera, V.; Grepioni, F.
Organometallics 1998, 17, 3027.
* Corresponding authors. J .A.C.: Fax: int + 34-985103446. E-
mail: jac@sauron.quimica.uniovi.es. F.G.: Fax: int + 39-079212069.
E-mail: grepioni@ssmain.uniss.it.
† Universidad de Oviedo.
‡ Universita` di Sassari.
(1) For reviews on late-transition-metal amido complexes, see: (a)
Fryzuk, M. D.; Montgomery, C. D. Coord. Chem. Rev. 1989, 95, 1. (b)
Bryndza, H. E. Chem. Rev. 1988, 88, 1163.
(2) For reviews on bi- and polynuclear ruthenium complexes con-
taining N-donor ligands, see: (a) Cabeza, J . A.; Ferna´ndez-Colinas, J .
M. Coord. Chem. Rev. 1993, 126, 319. (b) Bruce, M. I.; Cifuentes, M.
P.; Humphrey, M. G. Polyhedron 1991, 10, 277.
(3) (a) Feng, S. G.; White, P. S.; Templeton, J . L. Organometallics
1995, 14, 5184. (b) Rahim, M.; Bushweller, C. H.; Ahmed, K. J .
Organometallics 1994, 13, 4952, and references therein. (c) Powell, K.
R.; Pe´rez, P. J .; Luan, L.; Feng, S. G.; White, P. S.; Brookhart, M.;
Templeton, J . L. Organometallics 1994, 13, 1841. (d) Martin, G. C.;
Boncella, J . M.; Wucherer, E. J . Organometallics 1991, 10, 2804, and
references therein. (e) J oslin, F. L.; J ohnson, M. P.; Mague, J . T.;
Roundhill, D. M. Organometallics 1991, 10, 2781.
(8) Van der Lende, D. D.; Abboud, K. A.; Boncella, J . M. Inorg. Chem.
1995, 34, 5319.
(9) See, for example: (a) Cowan, R. L.; Trogler, W. C. J . Am. Chem.
Soc. 1989, 111, 4750. (b) Bryndza, H. E.; Fultz, W. C.; Tam, W.
Organometallics 1985, 4, 939.
(10) See, for example: (a) Daniel, T.; Knaup, W.; Dziallas, M.;
Werner, H. Chem. Ber. 1993, 126, 1981. (b) Esteruelas, M. A.; Lahoz,
F. J .; Oliva´n, M.; On˜ate, E.; Oro, L. A. Organometallics 1994, 13, 3315.
(11) (a) Cabeza, J . A.; del R´ıo, I.; Riera, V.; Ardura, D. J . Organomet.
Chem. 1998, 554, 117. (b) Bois, C.; Cabeza, J . A.; Franco, R. J .; Riera,
V.; Saborit, E. J . Organomet. Chem. 1998, 564, 201. (c) Cabeza, J . A.;
del R´ıo, I.; Riera, V. J . Organomet. Chem. 1997, 548, 255.
10.1021/om0005506 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 11/14/2000

Reactivity of Diynes
Organometallics, Vol. 19, No. 25, 2000 5425
Sch em e 1
Ch a r t 1
the bands of compound 1. In all cases, qualitative TLC
analysis of the resulting solutions indicated the presence
of several products in addition to an uneluted residue.
Chart 1 shows the schematic structures of the com-
pounds [Ru2(µ-NdCPh2)(µ-η2-CH2dCCH2CtCSiMe3)-
(CO)6] (2), [Ru3{µ-η2-NdCPh(C6H4)}(µ3-η4-PhOCH2CHd
CdCdCHCH2OPh)(CO)8] (3), [Ru3{µ3-η4-NdCPh-
(C6H4)CH(Me)CHdCdCMe}(CO)9] (4), [Ru3{µ-η2-Nd
CPh(C6H4)}(µ3-η4-PhCHdCHCtCPh)(CO)8] (5), and [Ru3-
{µ3-η4-PhCHCHdC(CPh)NdCPh(C6H4)}(CO)9] (6), which
are the major products of the reactions of cluster 1 with
1-trimethylsilyl-1,4-pentadiyne (2), 1,6-diphenoxy-2,4-
hexadiyne (3), 2,4-hexadiyne (4), and diphenylbutadiyne
(5 and 6). They were separated by chromatographic
workups from the corresponding reaction mixtures and
were characterized as follows.
Ch a r a cter iza tion of Com p ou n d 2. The binuclear
nature of this compound was indicated by its mi-
croanalysis and mass spectrum, which are consistent
with the structure depicted in Chart 1. Its IR spectrum
in the carbonyl region compares well with those known
for the binuclear alkenyl derivatives shown in Scheme
1,7 suggesting a similar arrangement of the ligands.
Although there are four different possibilities for the
binuclear metallacyclic derivative [Ru2{µ-PhCdCPhCPhd
CPhNdCPh(C6H4)}(µ-CO)(CO)4] (A, R ) Ph in Scheme
1).6 We have also shown that this type of reaction can
be extended to other internal alkynes containing one
phenyl group, such as 1-phenyl-1-propyne (A, R ) Me
in Scheme 1), whereas the reactions of 1 with other
types of alkynes lead only to binuclear derivatives
containing alkenyl ligands that arise from the insertion
of the alkynes into M-H bonds (B in Scheme 1).7 To
date, the formation of C-N bonds via insertion of
unsaturated molecules into the M-N bonds of amido
complexes is very uncommon, and it has only been
achieved with highly electrophilic substrates, such as
dimethyl acetylenedicarboxylate, carbon monoxide, car-
bonyl sulfide, carbon dioxide, acrylonitrile, or phenyl
isocyanate.8,9
The results obtained from the reactions of compound
1 with alkynes,7 summarized in Scheme 1, led us to
investigate the reactivity of compound 1 with diynes,
which were expected to be more reactive and, hence, to
provide a richer derivative chemistry than that of simple
alkynes. Moreover, very few reactions of ruthenium
carbonyl cluster complexes with diynes have previously
been described.12 We now report that compound 1 reacts
with 1-trimetilsilyl-1,4-pentadiyne, 1,6-diphenoxy-2,4-
hexadiyne, 2,4-hexadiyne, and diphenylbutadiyne, un-
der thermal conditions, to give products containing
ligands that derive from insertion reactions of the diynes
into Ru-H, Ru-C, and Ru-N bonds.
(12) See, for example: (a) Bruce, M. I.; Low, P. J .; Werth, A.; Skelton,
B. W.; White, A. H. J . Chem. Soc., Dalton Trans. 1996, 1551. (b) Bruce,
M. I.; Zaitseva, N. N.; Skelton, B. W.; White, A. H. Inorg. Chim. Acta
1996, 250, 129. (c) Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; White,
A. H. J . Organomet. Chem. 1997, 536-537, 93. (d) Tunik, S. P.;
Grachova, E. V.; Denisov, V. R.; Starova, G. L.; Nikol’skii, A. B.;
Dolgushin, F. M.; Yanovsky, A. I.; Struchkov, Y. T. Organomet. Chem.
1997, 536, 339. (e) Adams, C. J .; Bruce, M. I.; Skelton, B. W.; White,
A. H. J . Organomet. Chem. 1999, 589, 213. (f) Bruce, M. I.; Zaitseva,
N. N.; Skelton, B. W.; White, A. H. Russ. Chem. Bull. 1998, 47, 983.
(g) Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; White, A. H. Aust. J .
Chem. 1998, 51, 165. (h) Bruce, M. I.; Skelton, B. W.; White, A. H.;
Zaitseva, N. N. J . Organomet. Chem. 1998, 558, 197. (i) Lau, C. S. W.;
Wong, W, T. J . Chem. Soc., Dalton Trans. 1999, 2511. (j) Corrigan, J .
F.; Doherty, S.; Taylor, N. J .; Carty, A. J . Organometallics 1992, 11,
3160. (k) Corrigan, J . F.; Doherty, S.; Taylor, N. J .; Carty, A. J .
Organometallics 1993, 12, 1365.
Resu lts
Syn th esis. The reactions of compound 1 with diynes
were carried out in THF at reflux temperature, using
an excess (2- to 3-fold) of the diyne. Heating was stopped
when the IR spectra of the solutions no longer showed

5426 Organometallics, Vol. 19, No. 25, 2000
Cabeza et al.
Ch a r t 2
insertion of one of the alkyne fragments of 1-trimeth-
ylsilyl-1,4-pentadiyne into an M-H bond to give a
binuclear ynenyl derivative (Chart 2), the 1H NMR
spectrum of 2 unambiguously confirms the absence of
a terminal acetylenic hydrogen (structures E and F ) and
the presence of an alkenyl fragment which contains two
geminal H atoms (structure C), since it shows two
uncoupled resonances at δ 3.92 and 3.09 ppm, as
expected for geminal vinyl hydrogens.6 Moreover, the
H atoms of the methylenic CH2 fragment are observed
as two doublets (they couple to each other), also ruling
out the structures D and F , in which they should also
couple to the corresponding vinyl hydrogen. Therefore,
the structure shown in Chart 1 for compound 2 is
strongly supported by its analytical and spectroscopic
data.
Ch a r a cter iza tion of Com p ou n d 3. The trinuclear
nature of this compound was revealed by its microana-
lytical and FAB-MS data. Its 1H NMR spectum indi-
cated (a) the possible orthometalation of a phenyl ring
(several coupled resonances in the range 8.1-6.0 ppm),
(b) the absence of hydride ligands, and (c) the addition
of two hydrogen atoms to the original diyne framework
(signals at 3.29 (t, 10.7 Hz) and 2.99 (t, 10.0 Hz) ppm).
The multipliciy of these signals, in addition to selective
homonuclear decoupling experiments, indicated that
each of these hydrogen atoms is coupled to the hydro-
gens of a CH2 group, being therefore attached to the
carbon atom adjacent to the CH2 group.
The structure of compound 3 was unambiguosly
determined by X-ray diffraction methods (Chart 1,
Figure 1a). A selection of bond distances is given in
Table 1. The structure consists of an open triangle (V-
shaped) of ruthenium atoms in which the longest (open)
edge [3.502(1) Å] is spanned by the nitrogen atom of an
orthometalated 2,2-diphenyl-1-azavinylidene ligand,
which acts as a four-electron donor. A cis-1,6-diphenoxy-
2,3,4-hexatriene ligand interacts with the three ruthe-
nium atoms (Figure 1b) through the four C atoms
involved in the cumulene moiety, in such a way that
the central CdC double bond is parallel to the longest
edge of the metallic triangle. Curiously, although the
three C-C distances of the triene moiety are compa-
rable, ranging from 1.372(9) to 1.40(1) Å, the Ru-C
distances associated with the same carbon atoms range
from 2.052(6) to 2.296(7) Å, the shortest ones corre-
sponding to the bonds between the two central carbon
F igu r e 1. (a) Molecular structure of compound 3 (H atoms
omitted for clarity). Thermal ellipsoids are drawn at 30%
probability level. (b) Coordination of the cis-1,6-diphenoxy-
2,3,4-hexatriene ligand to the metal triangle in compound
3 (all remaining atoms omitted for clarity).
Ta ble 1. Selected In ter a tom ic Dista n ces (Å) in
Com p ou n d s 3-6
3
4
5
6
Ru(1)-Ru(2)
Ru(1)-Ru(3)
Ru(2)-Ru(3)
N(1)-Ru(1)
N(1)-Ru(3)
N(1)-C(10)
N(1)-C(19)
C(12)-Ru(3)
C(17)-Ru(3)
C(18)-Ru(3)
C(19)-Ru(1)
C(19)-Ru(2)
C(19)-Ru(3)
C(20)-Ru(1)
C(20)-Ru(2)
C(20)-Ru(3)
C(12)-C(17)
C(17)-C(18)
C(18)-C(19)
C(19)-C(20)
2.900(1)
3.502(1)
2.924(2)
2.111(6)
2.115(5)
1.299(9)
2.812(1)
3.381(1)
2.819(1)
2.107(6)
2.166(6)
1.263(10)
2.788(1)
3.534(1)
2.887(1)
2.132(4)
2.100(4)
1.259(7)
2.758(1)
2.825(2)
2.830(1)
2.12(1)
1.33(1)
1.44(1)
2.063(8)
2.296(7)
2.154(7)
2.224(7)
2.052(6)
2.075(6)
2.380(5)
2.224(5)
2.290(8)
2.32(1)
2.077(8)
2.296(8)
2.086(8)
2.205(8)
2.062(5)
2.195(5)
2.072(5)
2.251(5)
2.21(1)
2.300(7)
2.071(1)
2.19(1)
1.53(2)
1.51(1)
1.38(1)
1.43(1)
1.54(1)
1.53(1)
1.40(1)
1.37(1)
1.40(1)
1.372(9)
1.39(1)
1.384(8)
1.416(7)
1.368(7)
atoms and the central ruthenium atom and the longest
ones to the bonds between the two outer carbon atoms
and the outer ruthenium atoms (Figure 1b). This ligand
can be considered as a six-electron donor, since each Cd
C double bond is associated with a metal atom via a
π-type interaction. The ligand shell of the cluster is
completed by eight carbonyl ligands. Therefore, the
electron count of this cluster is 50, compatible with the
presence of only two metal-metal bonds between the
three Ru atoms.13

Reactivity of Diynes
Organometallics, Vol. 19, No. 25, 2000 5427
F igu r e 3. Molecular structure of compound 5 (H atoms
omitted for clarity). Thermal ellipsoids are drawn at 30%
probability level.
F igu r e 2. Molecular structure of compound 4 (H atoms
omitted for clarity). Thermal ellipsoids are drawn at 30%
probability level.
Ch a r a cter iza tion of Com p ou n d 4. The trinuclear
diyne framework (signals at 5.82 (d, 8.8 Hz) and 5.19
(d, 8.8 Hz) ppm). The multipliciy and the coupling
constants of these signals indicate that these hydrogen
atoms are located on adjacent carbon atoms.
nature of this compound was revealed by its mi-
1
croanalysis and mass spectrum. Its H NMR spectum
indicated (a) the possible orthosubstitution of a phenyl
ring (a complex multiplet, in the range 7.5-7.1 ppm,
accompanied by two doublets at 6.68 and 6.64 ppm), (b)
the absence of hydride ligands, and (c) the addition of
two hydrogen atoms to the original diyne framework
(signals at 5.29 (d, 8.2 Hz) and 4.20 (dq, 8.2 and 7.7 Hz)
ppm). The multipliciy and the coupling constants of
these signals indicate that these hydrogen atoms couple
to each other, but only one of them couples to a methyl
group. Therefore, these hydrogen atoms are attached
to the carbon atoms originally involved in one of the two
triple bonds of 2,4-hexadiyne.
The structure of compound 4 was determined by X-ray
diffraction methods (Chart 1, Figure 2). A selection of
bond distances is given in Table 1. The structure
consists of an open triangle (V-shaped) of ruthenium
atoms in which the longest (open) edge [3.381(1) Å] is
spanned by the nitrogen atom of a modified 2,2-
diphenyl-1-azavinylidene ligand, which has one of the
phenyl rings attached to the C5 carbon atom of a hexa-
2,3-diene-2,5-diyl fragment. This fragment interacts
with the three ruthenium atoms through the three
allenyl C atoms. While the C atoms of the two CdC
bonds interact with two Ru atoms in a π-fashion, C(20)
is also attached to the remaining Ru atom in a σ-fashion.
The two C-C distances of the allenyl moiety are
comparable [1.40(1) and 1.37(1) Å], while the Ru-C
distances associated with these carbon atoms via π-type
interactions range from 2.077(8) to 2.296(8) Å, the Ru-
(1)-C(20) distance (σ-type interaction) being 2.086(8)
Å. Overall, the complete organic ligand contributes eight
electrons to the cluster. The ligand shell of the molecule
is completed by nine carbonyl ligands. Therefore, the
electron count of this cluster is 50, compatible with the
presence of only two metal-metal bonds between the
three Ru atoms.13
The structure of compound 5 was determined by X-ray
diffraction methods (Chart 1, Figure 3). A selection of
bond distances is given in Table 1. The structure
consists of an open triangle of ruthenium atoms in which
the longest edge [3.533(1) Å] is spanned by the nitrogen
atom of an orthometalated 2,2-diphenyl-1-azavinylidene
ligand. A cis-1,4-diphenyl-3-buten-1-yne ligand interacts
with the three Ru atoms through the four C atoms
involved in the triple and double bonds, in such a way
that the C atoms of the CtC triple bond are parallel to
the longest edge of the metallic triangle, interacting
with the three metal atoms, as frequently observed for
alkyne ligands in trinuclear metal clusters,14,15 while
the C atoms of the CdC double bond are attached to
the same Ru atom as the metalated phenyl ring via a
π-type interaction. As expected, the distances involving
the C atoms of the four-electron donor CtC [1.368(7)
Å] and two-electron donor CdC [1.384(8) Å] moieties
are similar and shorter than that of the C-C single
bond [1.416(7) Å]; however, as a consequence of the
distortion imposed by the fact that the alkene and
alkyne fragments are rigidly attached to each other, the
Ru-C distances associated with these C atoms (Table
1) differ substantially from those observed in normal
ruthenium clusters containing µ3-η2-alkyne and η2-
alkene ligands.14,15 The ligand shell of the molecule is
completed by eight carbonyl ligands. Therefore, the
electron count of this cluster is 50, compatible with the
presence of only two metal-metal bonds between the
three Ru atoms.13
Ch a r a cter iza tion of Com p ou n d 6. As occurred
with compounds 3-5, the trinuclear nature of compound
6 was again revealed by microanalysis and mass
spectrometry. Its 1H NMR spectum also indicated (a)
the possible orthometalation or orthosubstitution of a
phenyl ring (several resonances in the range 8.2-6.6
ppm), (b) the absence of hydride ligands, and (c) the
addition of two hydrogen atoms to the original diyne
Ch a r a cter iza tion of Com p ou n d 5. The trinuclear
nature of this compound was again revealed by mi-
1
croanalysis and mass spectrometry. Its H NMR spec-
tum indicated (a) the possible orthometalation of a
phenyl ring (several coupled resonances in the range
8.1-5.5 ppm), (b) the absence of hydride ligands, and
(c) the addition of two hydrogen atoms to the original
(14) See, for example: (a) Sappa, E. J . Cluster Sci. 1994, 5, 211. (b)
Deabate, S.; Giordano, R.; Sappa, E. J . Cluster Sci. 1997, 8, 407.
(15) Smith, A: K. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Vol. 7 (Shriver, D. F.,
Bruce, M. I., Eds.); Pergamon: Oxford, UK, 1995; p 747, and references
therein.
(13) Mingos, D. M. P.; Wales, D. J . Introduction to Cluster Chemistry;
Prentice Hall International: Englewood Cliffs, NJ , 1990.

5428 Organometallics, Vol. 19, No. 25, 2000
Cabeza et al.
to give binuclear alkenyl derivatives,16 but no competi-
tive reactions between these clusters and internal and
terminal alkynes have been previously carried out.
However, just one observation (only one nonconjugated
alkyne has been studied) is not sufficient to unambigu-
ously propose a pattern of behaviour for nonconjugated
diynes.
The results obtained with 1,6-diphenoxy-2,4-hexa-
diyne, 2,4-hexadiyne and diphenylbutadiyne allow us
to state that conjugated diynes behave quite differently
from nonconjugated diynes in their reactions with
compound 1, since the characterized reaction products
(Chart 1, compounds 3-6), which are the major com-
ponents of the corresponding reaction mixtures, are
always trinuclear derivatives. In this case, the main-
tainance of the cluster nuclearity may be due to the
proximity of the two CtC triple bonds in the conjugated
diynes, which allows their interacion with the three
metal atoms of the cluster, thus preventing a subse-
quent cluster fragmentation.
Compounds 3-6 arise from multistep reaction path-
ways which involve not only the substitution of the
corresponding diyne for carbonyl ligands and the ortho-
metalation of a phenyl ring of the 2,2-diphenyl-1-
azavinylidene ligand17 but also a number of insertion
processes of unsaturated hydrocarbon fragments into
M-H, M-C, and M-N bonds, which deserve further
comments.
Compounds 4-6 contain two hydrogen atoms at-
tached to carbon atoms originally involved in CtC triple
bonds. These hydrogens (which correspond to the primi-
tive hydride of 1 plus that coming from the orthometa-
lation) must have been transferred from the metal to
the diyne carbon atoms. In the case of complex 3, this
process leads to a 1,2,3-triene (1,4-addition of hydrogen),
while in the case of 5, an enyne is formed (1,2-addition
of hydrogen). Although a 1,2-addition of hydrogen has
evidently taken place during the course of formation of
4 and 6, it is not clear whether the hydrogen transfer
occurs before or after the coupling of the orthometalated
1-azavinylidene ligand to the corresponding unsaturated
fragment.
F igu r e 4. Molecular structure of compound 6 (H atoms
omitted for clarity). Thermal ellipsoids are drawn at 30%
probability level.
framework (signals at 3.62 (d, 10.2 Hz) and 3.48 (d, 10.2
Hz) ppm). The multipliciy and the coupling constants
of these signals indicate that these hydrogen atoms are
located on adjacent carbon atoms.
Again, an X-ray diffraction study was necessary to
determine the structure of the compound (Chart 1,
Figure 4). A selection of bond distances is given in Table
1. The structure consists of a nearly regular triangle of
ruthenium atoms attached to an organic ligand which
results from the coupling of the N atom and the
metalated phenyl ring of an orthometalated 2,2-diphe-
nyl-1-azavinylidene ligand with the C2 and C4 carbon
atoms of an original cis-1,4-diphenyl-3-buten-1-yne
ligand (which arises from the hydrogenation of diphe-
nylbutadiyne). This ligand is attached to Ru(X) through
the carbons C1, C2, and C3, via a π-allyl-type interaction,
to Ru(Y) through the N atom, and to Ru(Z) through C1.
The complete ligand contributes six electrons to the
cluster. The ligand shell of the molecule is completed
by nine carbonyl ligands. In this case, the electron count
of this cluster is 48, compatible with the presence of
three metal-metal bonds between the three Ru atoms.13
Discu ssion
As far as we are aware, the synthesis of 1,2,3-trienes
has never been achieved by addition of dihydrogen to
conjugated diynes. However, the isolation of compound
3 confirms that the 1,4-addition of hydrogen to a
conjugated diyne is indeed possible if it is carried out
Diynes can be divided into two groups (a) those that
have the two triple CtC bonds separated by carbon
atoms and (b) those that have the two triple CtC bonds
in adjacent positions (conjugated). Both groups include
diynes having one or both CtC bonds in terminal or
internal positions within the carbon chain. One of the
diiynes used in this work, 1-trimethylsilyl-1,4-penta-
diyne, belongs to the first group, while the remaining
ones, 1,6-diphenoxy-2,4-hexadiyne, 2,4-hexadiyne, and
diphenylbutadiyne, belong to the second group.
The above-described results involving 1-trimethyl-
silyl-1,4-pentadiyne indicate that the chemical behavior
of nonconjugated diynes seems to be comparable to that
of monoalkynes in their reactions with complex 1
(Scheme 1), since a binuclear ynenyl derivative, which
results from the insertion of one of the two original
alkyne functionalities into a Ru-H bond, has been
isolated (Chart 1, compound 2). Interestingly, the
terminal alkyne fragment is preferred over the internal
one. It has previously been determined that complex 17
and many other ligand-bridged hydrido trinuclear clus-
ters react easily with both internal and terminal alkynes
(16) See, for example: (a) Boag, N. M.; Sieber, W. J .; Kampe, C. E.;
Knobler, C. B.; Kaesz, H. D. J . Organomet. Chem. 1988, 355, 385. (b)
Kaesz, H. D.; Xue, Z.; Chen. Y. J .; Knobler, C. B.; Sieber, W. J .; Boag,
N. M. Pure Appl. Chem. 1988, 60, 1245. (c) Krone-Schmidt, W.; Sieber,
W. J .; Knobler, C. B.; Kaesz, H. D. J . Organomet. Chem. 1990, 394,
433. (d) Xue, Z.; Sieber, W. J .; Knobler, C. B.; Kaesz, H. D. J . Am.
Chem. Soc. 1990, 112, 1825. (e) Cabeza, J . A.; Ferna´ndez-Colinas, J .
M.; Llamazares, A.; Riera, V. Organometallics 1992, 11, 4355.
(17) Previous examples of orthometalation of 2,2-diphenyl-1-
azavinylidene5-7 and benzophenone imine17a-h ligands are known. (a)
Werner, H.; Daniel, T.; Braun, T.; Nu¨rnberg, O. J . Organomet. Chem.
1993, 462, 309. (b) Bohanna, C.; Esteruelas, M. A.; Lo´pez, A. M.; Oro,
L. A. J . Organomet. Chem. 1996, 526, 73. (c) Daniel, T.; Mu¨ller, M.;
Werner, H. Inorg. Chem. 1991, 30, 3118. (d) Daniel, T.; Werner, H. Z.
Naturforsch. B 1992, 47, 1707. (e) Daniel, T.; Knaup, M.; Dziallas, M.;
Werner, H. Chem. Ber. 1993, 126, 1981. (f) Werner, H.; Daniel, T.;
Braun, T.; Nu¨rnberg, O. J . Organomet. Chem. 1994, 480, 145. (g)
Daniel, T.; Werner, H. J . Chem. Soc., Dalton Trans. 1994, 221. (h)
Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro, L. A.
Organometallics 1995, 14, 2496. (i) Barea, G.; Esteruelas, M. A.; Lledo´s.
A.; Lo´pez, A. M.; On˜ate, E.; Tolosa J . I. Organometallics 1998, 17, 4065.
(h) Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lo´pez, A. M.; On˜ate, E.;
Tolosa J . I. Organometallics 2000, 19, 275.

Reactivity of Diynes
Organometallics, Vol. 19, No. 25, 2000 5429
on a metal cluster. Therefore, the preparation of 1,2,3-
trienes by catalytic hydrogenation of conjugated diynes
may be feasible if an appropriate metal cluster is used
as catalyst precursor.
M-N bonds of metal clusters. Among these processes,
the 1,4-addition of hydrogen to a conjugated diyne
(occurred in 3) and the C-N bond-forming reaction
(occurred in 6) are remarkable. The first one has never
been observed previously, and it seems that it can only
happen on polynuclear metal clusters. The C-N bond-
forming process, occurring by insertion of a coordinated
alkyne into a M-N bond, is very rare when a weakly
electrophilic alkyne is involved.7
In compounds 4 and 6, a new C-C bond has been
formed, assembling the previously metalated phenyl
ring with the terminal carbon atom of the original diyne.
More interesting is the formation of a new C-N bond
in compound 6. As commented above, it has not been
established whether these couplings occur before or
after the hydrogenation of the original diyne. Insertion
reactions of alkynes into M-C bonds are frequent in
carbonyl ruthenium cluster chemistry.15 However, in-
sertion reactions into M-N bonds of amido complexes
are very rare, being restricted to highly electrophilic
unsaturated molecules, such as dimethyl acetylenedi-
carboxylate, carbon monoxide, carbonyl sulfide, carbon
dioxide, or phenyl isocyanate.8,9 Therefore, although
normal amido complexes have no tendency to insert
weakly electrophilic alkynes into their M-N bonds,3 the
results described herein support the suggestion that this
is not always the case for 1-azavinylidene complexes.
In fact, in the reactions of compound 1 with alkynes,
we have observed products that result from the insertion
of the alkyne into a Ru-N bond when the alkyne used
is internal and contains at least one phenyl group
(Scheme 1).7
Exp er im en ta l Section
Gen er a l Da ta . Solvents were dried over sodium diphenyl
ketyl (THF, hydrocarbons) or CaH2 (dichloromethane) and
distilled under nitrogen prior to use. The reactions were
carried out under nitrogen, using Schlenk-vacuum line
techniques, and were routinely monitored by solution IR
spectroscopy (carbonyl stretching region) and by spot TLC
(silica gel). Compound 1 was prepared as described previously.5
The diynes used were obtained from Aldrich and/or Farchan.
IR spectra were recorded in solution on a Perkin-Elmer FT
1720-X spectrophotometer, using 0.1 mm CaF2 cells. 1H NMR
spectra were run at room temperature with Bruker AC-200
and AC-300 instruments, using internal SiMe4 as standard
(δ ) 0 ppm). FAB-MS were obtained from the University of
Santiago de Compostela Mass Spectroscopic Service; data
given refer to the most abundant molecular ion isotopomer.
Microanalyses were obtained from the University of Oviedo
Analytical Service.
Attempts to transform compounds 3-6 into other
products under thermal conditions have failed. For
example, attempts to make compound 6 or a compound
of structure analogous to that of 4 by thermolysis of 5
and attempts to make a compound of structure analo-
gous to that of 6 by thermolysis of 4 were unsuccessful.
These results suggest that the C-N bond-forming step
is not the final step in the mechanism that leads to
complex 6. Moreover, although 5 and 6 may come from
a common reaction intermediate species, the pathways
that lead from that intermediate to 5 and 6 are
independent. These results also indicate that in the
reactions that lead to compounds 3-6, the thermody-
namic stability of the reaction intermediates as well as
the activation energies associated with their transfor-
mations are strongly affected by the nature of the
substituents of the diyne ligand.
[Ru 2(µ-NdCP h 2)(µ-η2-CH2dCCH2CtCSiMe3)(CO)6] (2).
A solution of 1 (250 mg, 0.327 mmol) and 1-trimethylsilyl-1,4-
pentadiyne (127 µL, 0.982 mmol) in THF (20 mL) was stirred
at reflux temperature for 85 min. The color changed from
orange to red. The solvent was removed under reduced
pressure, the residue was extracted into hexane (ca. 2 mL),
and the extract was separated by column chromatography (10
× 2 cm) on neutral alumina (activity I). Hexane washed out
the free diyne. Hexane-dichloromethane (2:1) eluted a yellow
band, which gave compound 2 after solvent removal (87 mg,
38%). Anal. Found: C, 47.36; H, 3.48; N, 1.98. MS (m/z): 689
[M+]. Calcd for C27H23NO6Ru2Si: C, 47.16; H, 3.37; N, 2.04.
fw: 687.73. IR (hexane): ν(CO) 2080 (s), 2054 (vs), 2005 (vs),
1
1991 (s), 1986 (s), 1955 (sh) cm-1. H NMR (CD2Cl2): δ 7.4-
6.8 (m, 10 H), 3.92 (s, 1 H of vinyl CH2), 3.89 (d, 17.9 Hz, 1 H
of methylenic CH2), 3.28 (d, 17.9 Hz, 1 H of methylenic CH2),
3.09 (s, 1 H of vinyl CH2), 0.09 (s, 9 H, SiMe3) ppm.
[Ru 3{µ-η2-NdCP h (C6H4)}(µ3-η4-P h OCH2CHdCdCdCH-
CH2OP h )(CO)8] (3). A solution of 1 (150 mg, 0.196 mmol) and
1,6-diphenoxy-2,4-hexadiyne (157 mg, 0.598 mmol) in THF (20
mL) was stirred at reflux temperature for 1.5 h. The color
changed from orange to brown. The solvent was partially
removed under reduced pressure, and the remaining solution
(ca. 2 mL) was separated by TLC on silica gel. Hexane eluted
free diyne and a small amount of starting material 1. Multiple
elution with hexane-dichloromethane (2:1) afforded several
bands. The second and major band, yellow, was extracted with
dichloromethane to give compound 3 after crystallization from
dichloromethane-hexane (48 mg, 25%). Anal. Found: C, 48.39;
Con clu d in g Rem a r k s
In the present work, we have shown that, in their
reaction with complex 1, the chemical behavior of
nonconjugated diynes seems comparable to that of
monoalkynes, giving binuclear alkenyl derivatives,
whereas conjugated diynes help maintain the cluster
integrity, leading to trinuclear products.
The isolated compounds (2-6) contain new organic
ligands that can be described as substituted 1-yn-3-enyl
(in 2), 1,2,3-triene (in 3), 1,2-dienyl (in 4), 1-en-3-yne
(in 5), and 2-(N-imido)-1,2,3-allyl-1-yl (in 6) ligands.
These ligands arise from a number of interesting
chemical transformations that include carbonyl substi-
tution, diyne coordination to the cluster framework,
orthometalation of a phenyl ring of the original 2,2-
diphenyl-1-azavinylidene ligand, hydrogenation of the
unsaturated hydrocarbon fragment, and C-C and C-N
bond-formation processes, representing excellent ex-
amples of insertion of diynes into M-H, M-C, and
H, 2.41; N, 1.54. MS (m/z): 972 [M+]. Calcd for C39H25NO10
-
Ru3: C, 48.25; H, 2.60; N, 1.44. fw: 970.87. IR (CH2Cl2): ν-
(CO) 2092 (s), 2059 (vs), 2043 (s), 1999 (m), 1985 (w), 1964
(w) cm-1 1H NMR (CDCl3): δ 8.01 (d, 6.0 Hz, 1 H), 7.4-6.0
.
(m, 18 H), 5.09 (dd, 10.0 and 6.5 Hz, 1 H of CH2), 4.75 (dd,
10.7 and 9.5 Hz, 1 H of CH2), 4.70 (dd, 10.7 and 9.5 Hz, 1 H of
CH2), 3.80 (dd, 10.0 and 6.5 Hz, 1 H of CH2), 3.29 (t, 10.7 Hz,
1 H, vinyl CH), 2.99 (t, 10.0 Hz, 1 H, vinyl CH) ppm.
[Ru 3{µ3-η4-NdCP h (C6H4)CH(Me)CHdCdCMe}(CO)9] (4).
A solution of 1 (200 mg, 0.262 mmol) and 2,4-hexadiyne (74
mg, 0.945 mmol) in THF (20 mL) was stirred at reflux
temperature for 1.5 h. The orange color slightly darkened. The

5430 Organometallics, Vol. 19, No. 25, 2000
Ta ble 2. Cr ysta l Da ta a n d Deta ils of Mea su r em en t for Com p ou n d s 3-6
Cabeza et al.
3
4
5
6
formula
fw
cryst syst
space group
a, Å
C
39H25NO10Ru3
C28H17NO9Ru3
814.64
orthorhombic
P212121
10.106(4)
14.643(9)
18.880(9)
90
90
90
2794(2)
4
C37H21NO8Ru3
910.76
monoclinic
P21/c
15.759(9)
10.818(6)
20.824(9)
90
107.92(6)
90
3378(3)
4
C38H21NO9Ru3‚(CH2Cl2)x (x<1)
970.81
monoclinic
P21/a
19.668(8)
9.327(8)
20.967(9)
90
106.42(3)
90
3689(4)
4
949.40
triclinic
P1h
12.445(3)
13.029(4)
13.946(5)
76.20(3)
72.28(2)
87.23(2)
2091.1(11)
2
b, Å
c, Å
R, deg
â, deg
γ, deg
vol, Å3
Z
F(000)
1912
1.748
1.272
0.24 × 0.22 × 0.12
293(2)
3-25
-23/22, 0/11, 0/24
7057
1584
1.937
1.656
1784
1.791
1.378
930
1.508
1.137
D
calcd, g/cm3
µ, mm-1
cryst size, mm
temp, K
0.25 × 0.22 × 0.20
0.20 × 0.16 × 0.12
0.22 × 0.16 × 0.16
293(2)
293(2)
223(2)
θ limits, deg
3-25
0/12, 0/17, 0/22
2788
3-25
-18/17, 0/12, 0/18
5772
3-23
min/max h, k, l
no. of reflns collected
unique reflns
-13/13, -13/14, 0/12
5885
5383
6420
2758
5306
reflns with I > 2σ(I)
no. of params
GOF on F2
4925
442
0.955
2558
370
1.369
3456
448
0.929
3124
433
0.921
R1 (on F, I > 2σ(I))
0.0657
0.1934
0.0367
0.0985
0.0304
0.0928
0.0538
0.1672
wR2 (on F2, all data)
solvent was partially evaporated under reduced pressure (to
ca. 2 mL), and the remaining solution was separated by column
chromatography (10 × 2 cm) on neutral alumina (activity I).
Hexane washed out the free diyne and a small amount of
compound 1. Hexane-dichloromethane (5:1) eluted a yellow
band, which gave compound 4 after solvent removal (36 mg,
17%). Anal. Found: C, 41.46; H, 2.10; N, 1.64. MS (m/z): 816
[M+]. Calcd for C28H17NO9Ru3: C, 41.28; H, 2.10; N, 1.72. fw:
814.69. IR (CH2Cl2): ν(CO) 2078 (s), 2054 (s), 2029 (vs), 2009
(m), 1988 (w) cm-1. 1H NMR (CDCl3): δ 7.5-7.1 (m, 7 H), 6.68
(d, 7.5 Hz, 1 H), 6.64 (d, 7.5 Hz, 1 H), 5.29 (d, 8.2 Hz, 1 H,
vinyl CH), 4.20 (dq, 8.2 and 7.7 Hz, 1 H, alkyl CH), 2.97 (s, 3
H, Me), 1.72 (d, 7.7 Hz, 3 H, Me) ppm.
Calcd for C38H21NO9Ru3: C, 48.62; H, 2.25; N, 1.49. fw: 938.83.
IR (CH2Cl2): ν(CO) 2068 (s), 2029 (vs), 1991 (m), 1978 (w) cm-1
.
1H NMR (CDCl3): δ 8.2-6.7 (m, 17 H), 6.83 (d, 7.4 Hz, 1 H),
6.61 (d, 7.4 Hz, 1 H), 3.62 (d, 10.2 Hz, 1 H, alkyl CH), 3.48 (d,
10.2 Hz, 1 H, allyl CH) ppm.
Cr ysta l Str u ctu r e Ch a r a cter iza tion of Com p ou n d s 3,
4, 5, a n d 6. X-ray diffraction data were collected on a NONIUS
CAD-4 diffractometer equipped with a liquid nitrogen Oxford-
Cryostream device. Crystal data and details of mesurements
are summarized in Table 2. SHELXL9718a was used for
structure solution and refinement based on F2. SCHAKAL9718b
was used for the graphical representation of the results.
Common to all compounds: Mo KR radiation, λ ) 0.71069 Å,
graphite monochromator, Ψ-scan absorption correction, all
non-H atoms refined anisotropically. The H atoms were added
in calculated positions and refined riding on their respective
C atoms. The presence of disordered dichloromethane was
detected in compound 6, corresponding to less than one solvent
molecule per formula unit.
[R u 3{µ-η2-NdCP h (C6H 4)}(µ3-η4-P h CH dCH CtCP h )-
(CO)8] (5) an d [Ru 3{µ3-η4-P h CHCHdC(CP h )NdCP h (C6H4)}-
(CO)9] (6). A solution of 1 (500 mg, 0.654 mmol) and
diphenylbutadiyne (390 mg, 1.929 mmol) in THF (50 mL) was
stirred at reflux temperature for 2.5 h. The color changed from
orange to brown. The solvent was partially removed under
reduced pressure, and the remaining solution (ca. 3 mL) was
separated by TLC on silica gel. Hexane eluted free diyne and
a small amount of starting material 1 (first band). Multiple
elution with hexane-dichloromethane (10:1) afforded several
bands. The second band, yellow, led to compound 5 after
solvent removal (148 mg, 25%). The third band, orange, led to
compound 6 after solvent removal (62 mg, 10%).
Ack n ow led gm en t. This work was supported by the
Spanish DGES (Grant PB95-1042) and the Italian
MURST. M.M. thanks the Spanish Ministerio de Edu-
cacio´n y Cultura for a predoctoral fellowship (FPI
program).
Su p p or tin g In for m a tion Ava ila ble: ORTEP pictures
and tables of bond distances and angles, fractional atomic
coordinates, and anisotropic thermal parameters for com-
pounds 3-6. This material is available free of charge via the
Internet at http://pubs.acs.org.
An a lytica l a n d Sp ectr oscop ic Da ta for Com p ou n d 5.
Anal. Found: C, 48.20; H, 2.57; N, 1.48. MS (m/z): 912 [M+].
Calcd for C37H21NO8Ru3: C, 48.79; H, 2.32; N, 1.54. fw: 910.82.
IR (CH2Cl2): ν(CO) 2078 (s), 2048 (vs), 2029 (s), 2005 (m), 1986
1
(sh), 1964 (w) cm-1. H NMR (CDCl3): δ 8.03 (d, 7.4 Hz, 1 H),
7.80 (d, 6.9 Hz, 1 H), 7.5-6.7 (m, 15 H), 6.19 (d, 7.8 Hz, 1 H),
5.82 (d, 8.8 Hz, 1 H, vinyl CH), 5.56 (d, 7.8 Hz, 1 H), 5.19 (d,
8.8 Hz, 1 H, vinyl CH) ppm.
OM0005506
(18) (a) Sheldrick, G. M. SHELXL97, Program for Crystal Structure
Determination; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(b) Keller, E. SCHAKAL97, Graphical Representation of Molecular
Models; University of Freiburg: Freiburg, Germany, 1997.
An a lytica l a n d Sp ectr oscop ic Da ta for Com p ou n d 6.
Anal. Found: C, 48.82; H, 2.31; N, 1.28. MS (m/z): 940 [M+].