Routes to ruthenium-cobalt clusters and dicobalt complexes with new alkoxysilyl- or sulfur-functionalized alkynes. X-ray structures of [NEt4][RuCo3(CO)10{μ4- η2-HC2(CH2)2OC(O) NH(CH2)3Si(OEt)3}]

Article abstract of DOI:10.1021/om020965m

Two general approaches are presented and compared to covalently link metal clusters to alkynes terminated with a trialkoxysilyl or a thioether group. They consist in the direct reaction of the functional alkyne with the cluster or in the functionalization of an alkyne already coordinated to the cluster. These are applied to the tetrahedral mixed-metal cluster [NEt₄][RuCo₃(CO)₁₂] (NEt₄·1). Complexes with the new alkynes HC≡C(CH₂)₂OC(O) NH(CH₂)₃Si(OEt)₃ (L¹), HC≡CCH₂NHC(O)NH(CH₂)₃Si(OEt)₃ (L²), and HC≡CCH₂NHC(O)NHC₆ H₂SMe (L³) have been characterized, and the crystal structures of [NEt₄][RuCo₃(CO)₁₀ {μ₄-η²-HC₂(CH₂)₂ OC(O)NH(CH₂)₃Si(OEt)₃}] (NEt₄·2a) and [Co₂(CO)₆ {μ₂-η²HC₂CH₂NHC(O)NH (CH₂)₃Si(OEt)₃}] (9) have been determined by X-ray diffraction.

Full text of DOI:10.1021/om020965m

2688
Organometallics 2003, 22, 2688-2693
Rou tes to Ru th en iu m -Coba lt Clu ster s a n d Dicoba lt
Com p lexes w ith New Alk oxysilyl- or
Su lfu r -F u n ction a lized Alk yn es. X-r a y Str u ctu r es of
[NEt4][Ru Co3(CO)10{µ4-η2-HC2(CH2)2OC(O)NH(CH2)3Si(OEt)3}]
a n d [Co2(CO)6{µ2-η2-HC2CH2NHC(O)NH(CH2)3Si(OEt)3}]
Aldjia Choualeb,† J acky Rose´,† Pierre Braunstein,*,† and Richard Welter‡
Laboratoire de Chimie de Coordination (UMR 7513 CNRS), and
Laboratoire DECMET (UMR 7513 CNRS), Universite´ Louis Pasteur,
4 rue Blaise Pascal, F-67070 Strasbourg Cedex, France
Received November 22, 2002
Two general approaches are presented and compared to covalently link metal clusters to
alkynes terminated with a trialkoxysilyl or a thioether group. They consist in the direct
reaction of the functional alkyne with the cluster or in the functionalization of an alkyne
already coordinated to the cluster. These are applied to the tetrahedral mixed-metal
cluster [NEt4][RuCo3(CO)12] (NEt4‚1). Complexes with the new alkynes HCtC(CH2)2-
OC(O)NH(CH2)3Si(OEt)3 (L1), HCtCCH2NHC(O)NH(CH2)3Si(OEt)3 (L2), and HCtCCH2-
NHC(O)NHC6H4SMe (L3) have been characterized, and the crystal structures of [NEt4]-
[RuCo3(CO)10{µ4-η2-HC2(CH2)2OC(O)NH(CH2)3Si(OEt)3}] (NEt4‚2a ) and [Co2(CO)6{µ2-η2-
HC2CH2NHC(O)NH(CH2)3Si(OEt)3}] (9) have been determined by X-ray diffraction.
In tr od u ction
with the metals in a µ4-η2-bonding mode.3,4 Alterna-
tively, these clusters may be viewed as having a closo
structure in which the two carbon atoms originating
from the alkyne are part of the skeleton. The stability
of the metal-carbon σ bonds explains that subsequent
reactions may occur by breaking of metal-metal bond-
(s) and partial cluster fragmentation rather than by
splitting of the organic moiety.5
Covalent linking rather than dative bonding of a
functional ligand to a metal cluster represents a sig-
nificant advantage to avoid leaching phenomena and is
also gaining increasing attention in heterogeneous
catalysis.6 Two strategies may be envisaged to link
covalently a metal cluster to a functional alkyne: either
by the reaction of a metal cluster with the desired
functional alkyne (route A2 in Scheme 1) or by the
functionalization of an organic backbone already linked
to the metal cluster (route B2 in Scheme 1).
It is not obvious that both methods may be used
indiscriminately, but if they can, a comparative study
of their respective advantages/disadvantages should be
particularly instructive. In all cases, the chemo- and
regioselectivity of the reactions represent central issues
to be investigated. A prerequisite in approach A is that
the functional group -FG will not compete with the
alkyne in the reaction with the cluster (A2). Approach
The current interest in stable functional metal clus-
ters that could be subsequently covalently anchored onto
surfaces or act as precursors to new cluster-derived
nanomaterials has led us to consider the use of alkynes
as a way to introduce the desired functionality, such as
a -Si(OR)3 group, owing to its ability to condense with
surface OH groups of inorganic supports and to form
sol-gel materials,1 or a thiol or thioether for, for
example, the formation of organized monolayers on gold
surfaces.2 Indeed, reactions of alkynes with carbonyl-
metal clusters afford a considerable diversity of struc-
tural types and bond activation processes,3 and the
stability of the products is largely due to the formation
of covalent metal-carbon bonds, usually involving a
triangular or rectangular face of the metal polyhedron.
If one considers the large family of tetrahedral metal
clusters, the products generally obtained are of the
butterfly type, with the organic fragment interacting
* Corresponding author. E-mail: braunst@chimie.u-strasbg.fr.
† Laboratoire de Chimie de Coordination (UMR 7513 CNRS).
‡ Laboratoire DECMET (UMR 7513 CNRS).
(1) (a) Braunstein, P.; Cauzzi, D.; Predieri, G.; Tiripicchio, A. J .
Chem. Soc., Chem. Commun. 1995, 229-230. (b) Corriu, R. J . P.;
Leclercq, D. Angew. Chem., Int. Ed. Engl. 1996, 35, 1420-1436. (c)
Hu¨sing, N.; Schubert, U. Angew. Chem., Int. Ed. 1998, 37, 22-45. (d)
Schweyer, F.; Braunstein, P.; Estourne`s, C.; Guille, J .; Kessler, H.;
Paillaud, J .-L.; Rose´, J . Chem. Commun. 2000, 1271-1272. (e) Be-
zombes, J . P.; Chuit, C.; Corriu, R. J . P.; Reye´, C. J . Organomet. Chem.
2002, 643-644, 453-460. (f) Boury, B.; Corriu, R. J . P. Chem.
Commun. 2002, 795-802.
(2) See for example: (a) Dhirani, A.; Zehner, R. W.; Hsung, R. P.;
Guyot-Sionnest, P.; Sita, L. R. J . Am. Chem. Soc. 1996, 118, 3319-
3320. (b) Hasan, M.; Bethell, D.; Brust, M. J . Am. Chem. Soc. 2002,
124, 1132-1133, and references therein.
(3) (a) Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983,
83, 203-239. (b) Raithby, P.; Rosales, M. J . Adv. Inorg. Chem.
Radiochem. 1985, 29, 169-247.
(4) (a) Chetcuti, M. J .; Fanwick, P. E.; Gordon, J . C. Inorg. Chem.
1991, 30, 4710-4717. (b) Waterman, S. M.; Humphrey, M. G.; Tolhurst,
V.-A.; Bruce, M. I.; Low, P. J .; Hockless, D. C. R. Organometallics 1998,
17, 5789-5795. (c) Ferrand, V.; Su¨ss-Fink, G.; Neels, A.; Stoeckli-
Evans, H. Eur. J . Inorg. Chem. 1999, 853-862. (d) Zhu, B.-H.; Zhang,
W.-Q.; Zhao, Q.-Y.; Bian, Z.-G.; Hu, B.; Zhang, Y.-H.; Yin, Y.-Q.; Sun,
J . J . Organomet. Chem. 2002, 650, 181-187.
(5) Braunstein, P.; Rose´, J .; Bars, O. J . Organomet. Chem. 1983,
252, C101-C105.
(6) Smith, G. V.; Notheisz, F. In Heterogeneous Catalysis in Organic
Chemistry; Academic Press: San Diego, CA, 1999.
10.1021/om020965m CCC: $25.00 © 2003 American Chemical Society
Publication on Web 05/23/2003

Routes to Ruthenium-Cobalt Clusters
Organometallics, Vol. 22, No. 13, 2003 2689
Sch em e 1. Gen er a l Ap p r oa ch es for th e
In cor p or a tion of F u n ction a l Alk yn es in to Meta l
Clu ster s, FG ) -Si(OR)3 or -SR
B offers the potential of using a larger diversity of
organic substituents but requires that the first step (B1),
i.e., the binding of the alkyne to the cluster, occur with
maximum selectivity and efficiency. It also requires that
at least one intact organic function remain available for
further transformation (B2). It appeared to us that, to
the best of our knowledge, strategy B has not been
previously applied to cluster chemistry. We decided to
explore and compare these two approaches, using the
mixed-metal cluster [RuCo3(CO)12]- (1) as precursor (as
+
NEt4 salt throughout). This cluster is known to react
with alkynes5,7 and offers the advantage over the related
[Co4(CO)12] to allow a study of the metalloselectivity of
the reaction.
F igu r e 1. View of the molecular structure of the anionic
cluster in NEt4‚2a . Hydrogen atoms have been omitted for
clarity. Thermal ellipsoids are drawn at the 50% probability
level. All hydrogen atoms have been placed mathematically
except for H(11). Selected bond lengths (Å) and angles
(deg): Ru(1)-Co(1) ) 2.745(2), Ru(1)-Co(2) ) 2.557(2), Ru-
(1)-Co(3) ) 2.5240(19), Ru(1)-C(12) ) 2.160(10), Co(1)-
Co(2) ) 2.464(2), Co(1)-Co(3) ) 2.449(2), Co(1)-C(11) )
1.985(10), Co(2)‚‚‚Co(3) ) 3.560, Co(2)-C(11) ) 2.091(10),
Co(2)-C(12) ) 2.048(9), Co(3)-C(11) ) 2.073(11), Co(3)-
C(12) ) 2.170(10), C(11)-C(12) ) 1.378; Co(2)-Ru(1)-Co-
(1) ) 55.25(6), Co(3)-Ru(1)-Co(1) ) 55.21(5), Co(2)-
Co(1)-Ru(1) ) 57.81(6), Co(3)-Co(1)-Ru(1) ) 58.51(7),
Co(1)-Co(3)-Ru(1) ) 66.98(6). Dihedral angle between the
wings ) 117°. The carbonyl ligand C(8)O(8) conforms to
the semibridging category of Crabtree-Lavin.10
Resu lts a n d Discu ssion
The new alkyne L1 was prepared in high yield by
condensation of 3-butyn-1-ol and 3-(triethoxysilyl)pro-
pylisocyanate in the presence of triethylamine (eq 1).
1
It was characterized by H, 13C, and 29Si NMR and IR
spectroscopy (see Experimental Section).
have been formed, in a 3:2 ratio, which differ in the
orientation of the alkyne with respect to the Co-Ru
hinge but could not be separated by column chroma-
tography. Formation of such isomers is not uncommon
in mixed-metal clusters, but the stereoelectronic factors
that govern their ratio are not yet clear.8 On the basis
of experiments carried out with related RuCo3 clusters
bearing the alkyne ΗCtCMe(dCH2),9 we suggest that
Reaction of L1 with 1 afforded cluster 2 by selective
alkyne insertion into a Co-Co bond (eq 2). Its H NMR
1
1
the more deshielded H NMR signal should be assigned
to the Co-bound CH proton. The cluster identified by
X-ray diffraction, 2a , has the CH group attached to Co
(Figure 1). The main bonding parameters in this 60-
electron cluster are given in the caption of Figure 1 and
are comparable to those in related molecules.3,5 The four
metal atoms form a butterfly skeleton where the ruthe-
nium atom occupies a hinge position. The alkyne is
coordinated to the concave side such that the C-C bond
is parallel to the hinge of the butterfly. It coordinates
to all metal atoms in a µ4-η2-mode, leading to a distorted
closo RuCo3C2 octahedral framework with 7 skeletal
electron pairs. For comparison, we explored the pos-
spectrum contains two singlets for the alkyne CH proton
at δ 8.74 and 8.27, indicating that two isomers 2a /2b
(8) Fox, J . R.; Gladfelter, W. L.; Geoffroy, G. L.; Tavanaiepour, I.;
Abdel-Mequid, S.; Day, V. W. Inorg. Chem. 1981, 20, 3230-3237.
(9) Choualeb, A.; Rose´, J .; Braunstein, P.; Welter, R., manuscript
in preparation.
(7) Braunstein, P.; J iao, F. Y.; Rose´, J .; Granger, P.; Balegroune,
F.; Bars, O. Grandjean, D. J . Chem. Soc., Dalton Trans. 1992, 2543-
2550.

2690 Organometallics, Vol. 22, No. 13, 2003
Choualeb et al.
Sch em e 2
with 3-butyn-1-ol to give 5, which was then reacted with
3-(triethoxysilyl)propylisocyanate to afford 4 (Scheme
3). Interestingly, 4 was obtained even in the absence of
triethylamine, but the reaction is more rapid if the latter
is used.
We then examined the behavior of alkynes carrying
an amine instead of an alcohol function. The new
alkynes L2 and L3 were prepared in quantitative yield
by condensation of propargylamine with a functional
isocyanate11 (route A1, eqs 3, 4) and reacted with 1
(route A2). This afforded clusters 6a /6b in a 5:1 ratio
and 7a /7b in 2:1 ratio, respectively (eqs 5, 6).
Sch em e 3. Alter n a tive P r oced u r es for th e
Syn th esis of 4
sibility of obtaining 2 following strategy B in Scheme 1
and thus first reacted 1 with 3-butyn-1-ol (Scheme 2).
This afforded the new cluster [RuCo3(CO)10(µ4-η2-
1
HC2(CH2)2OH]- (3), and again two H NMR CH reso-
nances were observed, at δ 8.74 and 8.25 in a 5:1 ratio,
for isomers 3a /3b.
These clusters were then reacted with 3-(triethoxysi-
lyl)propylisocyanate (route B2) to afford the correspond-
ing isomeric clusters 2a and 2b in a 5:1 ratio (Scheme
2). Interestingly, the reaction proceeded without the
need for additional triethylamine, in contrast to the
synthesis of L1. Although addition of NEt3 may increase
the rate of condensation, it also leads to some decom-
position of the precursor cluster. Owing to the ionic
nature of these clusters, it is difficult to monitor the
progress of the reaction by TLC. Furthermore, clusters
2 and 3 are both violet. IR spectroscopy indicates the
formation of the product, which has a characteristic ν-
(CdO) absorption at 1720 cm-1, but does not indicate if
the reaction has reached completion. The reaction
mixture was therefore stirred for 2 days at room
temperature.
For comparison, we reacted 1 with propargylamine
(Scheme 4). This afforded two isomeric clusters, 8a and
8b, in 88% yield (route B1). These clusters were char-
1
acterized by IR and H NMR spectroscopy. The 1H NMR
spectrum of the isomeric mixture 8a /8b contains two
singlets at δ 8.72 and 8.41 in a 2:1 ratio, respectively,
for the alkyne CH proton. These clusters were too
unstable to be stored for a prolonged period of time and
For comparison and in order to better characterize
coordinated L1, the latter was reacted with [Co2(CO)8],
and complex 4 was obtained in high yield (Scheme 3).
The latter was also obtained, in comparable yield, when
strategy B was followed. First, [Co2(CO)8] was reacted
(10) Crabtree, R. H.; Lavin, M. Inorg. Chem. 1986, 25, 805-812.
(11) Lindner, E.; Salesch, T.; Brugger, S.; Hoehn, F.; Wegner, P.;
Mayer, H. A. J . Organomet. Chem. 2002, 641, 165-172.

Routes to Ruthenium-Cobalt Clusters
Organometallics, Vol. 22, No. 13, 2003 2691
HCtCCH2NH}2CO].12 Complex 9 was characterized by
X-ray diffraction (Figure 2) and shows the usual Co2C2
tetrahedral core.13 The -Si(OEt)3 group appears steri-
cally unhindered, which is promising for further con-
densation reactions using the dicobalt or the cluster
complexes, and such studies are in progress.
In conclusion, we have examined and compared two
complementary approaches to covalently link dinuclear
complexes and metal clusters to functional alkynes
terminated with an alkoxysilyl or a thioether function.
The strategies depicted in Scheme 1 should be rather
general and since they are not necessarily interchange-
able, they should be useful in providing different
potential access to a given class of functional clusters.
Their use as precursors in materials science is the
subject of ongoing work.
F igu r e 2. View of the molecular structure of 9 (hydrogen
atoms omitted for clarity). Selected bond lengths (Å) and
angles (deg): Co(1)-Co(2) ) 2.474(1), Co(1)-C(7) ) 1.956-
(6), Co(1)-C(8) ) 1.970(6), Co(2)-C(7) ) 1.949(6), Co(2)-
C(8) ) 1.963(6), C(7)-C(8) ) 1.323(8); C(7)-Co(1)-C(8) )
39.4(2), C(7)-Co(2)-C(8) ) 39.5(2), Co(1)-C(7)-Co(2) )
78.6(2), Co(1)-C(8)-Co(2) ) 78.0(2).
Sch em e 4
Exp er im en ta l Section
All reactions and manipulations were carried out under an
inert atmosphere of purified nitrogen using standard Schlenk
tube techniques. Solvents were dried and distilled under
nitrogen before use: hexane, pentane, and tetrahydrofuran
over sodium-benzophenone, dichloromethane over phosphorus
pentoxide. Nitrogen (Air Liquide, R-grade) was passed through
BASF R3-11 catalyst and molecular sieves columns to remove
residual oxygen and water. Elemental C, H, N, and S analyses
were performed by the Service de Microanalyses du CNRS
(ULP Strasbourg). Infrared spectra were recorded on a Perkin-
Elmer 1600 series FTIR spectrometer. The 1H NMR spectra
were recorded at 300.13 MHz, 13C{1H} NMR spectra at 75.48
or 100.62 MHz, and 29Si{1H} at 79.48 MHz on a Bruker AC300,
AVANCE 300 or AVANCE 400 instrument. The ratios between
the isomeric clusters a and b determined from the alkyne CH
resonance may not always represent the situation at thermo-
dynamic equilibrium.
Syn th esis of HCtC(CH2)2OC(O)NH(CH2)3Si(OEt)3 (L1).
To a solution of 3-butyn-1-ol (19.75 mmol, 1.5 mL) and dry
triethylamine (17.85 mmol, 2.35 mL) in 10 mL of CH2Cl2,
cooled in an ice bath, was added dropwise a solution of
3-(triethoxysilyl)propylisocyanate (4.45 mL, 17.85 mmol) in 5
mL of CH2Cl2. After stirring overnight at room temperature,
the resulting solution was filtered, and the excess of 3-butyn-
1-ol and the solvent were evaporated under reduced pressure
were reacted immediately with 3-(triethoxysilyl)propy-
lisocyanate (route B2). This afforded the corresponding
isomeric clusters 6a and 6b in a 1:2 ratio (Scheme 4).
Similarly, their reaction with 4-(methylthio)phenyliso-
cyanate yielded 7a and 7b, in a 2:1 ratio. Method A gave
a better yield of functional cluster compared to B owing
to the limited stability of the intermediate clusters 8.
(12) Hong, F.-E.; Tsai, Y.-T.; Chang, Y.-C.; Ko, B.-T. Inorg. Chem.
2001, 40, 5487-5488.
(13) (a) Schore, N. E. In Comprehensive Organometallic Chemistry
II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford,
1995; Vol. 7. (b) Schore, N. E. Chem. Rev. 1988, 88, 1081-1119. (c)
Pauson, P. L. In Organometallics in Organic Synthesis, Aspects of a
Modern Interdisciplinary Field; de Meijere, A., tom Dieck, H., Eds.;
Springer: Berlin, 1988. (d) Housecroft, C. E.; J ohnson, B. F. G.; Khan,
M. S.; Lewis, J .; Raithby, P. R.; Robson, M. E.; Wilkinson, D. A., J .
Chem. Soc., Dalton Trans. 1992, 3171-3178. (e) Wong, W.-Y.; Lam,
H.-Y.; Lee, S.-M. J . Organomet. Chem. 2000, 595, 70-80. (f) Went, M.
J . Adv. Organomet. Chem. 1997, 41, 69-125.
Since single crystals of the functionalized cluster 6
or 7 could not be obtained, we reacted L2 and L3 with
[Co2(CO)8] in order to better characterize the new,
coordinated alkynes and obtained 9 and 10, respectively
(eqs 7, 8). Interestingly, these two complexes could not
be obtained according to method B since propargyl-
amine reacts with [Co2(CO)8] to give [{Co2(CO)6(µ2-η2-

2692 Organometallics, Vol. 22, No. 13, 2003
Choualeb et al.
to afford L1 as a colorless liquid (5.27 g, 16.60 mmol, 93%). IR
(CH2Cl2, cm-1): 3304 (s, ν≡CH), 2274 (vs, νC≡C), 1720 (vs, νCd
O), and 1517 (vs, δNH). 1H NMR (CDCl3): δ 0.53 (m, 2H, SiCH2),
anate (0.148 mmol, 0.037 mL). The mixture was stirred at
room temperature for 2 days. The solution was filtered through
Celite and concentrated. Violet crystals of NEt4‚2 (0.065 g,
0.065 mmol, 48%) were obtained after recrystallizing twice the
product from CH2Cl2/pentane. When this procedure was fol-
lowed, the ratio between isomers 2a and 2b was 5:1.
Syn th esis of [NEt4][Ru Co3(CO)10(µ4-η2-HC2(CH2)2OH)]
(NEt4‚3). Using a procedure similar to that described for NEt4‚
2, NEt4‚1 (0.223 g, 0.301 mmol) and 3-butyn-1-ol (0.105 g, 1.50
mmol, 0.114 mL) were refluxed in 50 mL of THF for 5 h. After
workup, NEt4‚3 (0.200 g, 0.264 mmol, 87%) was obtained as
dark violet crystals by recrystallization from CH2Cl2/hexane.
IR (CH2Cl2, ν(CO), cm-1): 2049 (m), 2003 (vs), 1970 (sh), 1819
(m). 1H NMR (CDCl3): δ 1.37 (m, 12H, CH3), 1.51 (br, OH),
2.72 (m, 2H, HC2CH2), 3.26 (m, 8H, NCH2), 3.44 (m, 2H,
OCH2), 8.25 (br s, 0.16H, HC2 of one isomer), 8.74 (br s, 0.84H,
HC2 of the other isomer). Anal. Calcd for C22H26Co3NO11Ru‚
1/2H2O: C, 33.75; H, 3.40; N, 1.75, Found: C, 33.57; H, 3.41;
N, 1.75.
3
1.12 (t, J (HH) ) 7 Hz, 9H, CH3), 1.52 (m, 2H, CH2CH2CH2),
1.92 (t, 4J (HH) ) 2.74 Hz, 1H, HCt), 2.41 (dt, 3J (HH) ) 7 Hz,
4J (HH) ) 2.74 Hz, 2H, tCCH2), 3.06 (m, 2H, NCH2), 3.72 (q,
3J (HH) ) 7 Hz, 6H, OCH2CH3), 4.05 (t, 3J (HH) ) 7 Hz, 2H,
OCH2), 5.27 (br, NH). 13C{1H} NMR (100.62 MHz, CDCl3): δ
7.46 (s, SiCH2), 18.16 (s, OCH2CH3), 19.32 (s, CH2CH2CH2),
23.13 (s, tCCH2), 42.84 (s, NCH2), 58.34 (s, OCH2CH3), 62.54
(s, OCH2), 69.58 (s, HCtC), 80.38 (s, HCtC), 156.07 (s, C)O).
29Si{1H} NMR (CDCl3): δ -45.93.
Syn th esis of HCtCCH2NHC(O)NH(CH2)3Si(OEt)3 (L2).
A solution of 3-(triethoxysilyl)propylisocyanate (1.64 g, 1.66
mL, 6.65 mmol) in 5 mL of CH2Cl2 was added dropwise to a
solution of propargylamine (7.32 mmol, 0.50 mL) in 15 mL of
CH2Cl2, cooled in an ice bath. After stirring overnight at room
temperature, the solvent was evaporated under vacuum and
the product was quantitatively obtained as a pale yellow solid
(2.00 g, 6.61 mmol). IR (KBr, cm-1): 3332 (s, ν≡CH), 1624 (vs,
Syn th esis of [Co2(CO)6{µ2-η2-HC2(CH2)2OC(O)NH(CH2)3-
Si(OEt)3}] (4). P r oced u r e A: Rea ction of [Co2(CO)8] w ith
L1. A solution of [Co2(CO)8] (0.387 g, 1.140 mmol) in 30 mL of
CH2Cl2 and L1 (0.522 g, 1.60 mmol) was stirred at room
temperature for 3 h. Completion of the reaction was revealed
from TLC by the disappearance of [Co2(CO)8]. The solvent was
then removed under vacuum. Extraction with hexane afforded
red viscous compound 4 (0.626 g, 1.04 mmol, 91%). IR (hexane,
cm-1): 2098 (vs), 2063 (vs), 2029 (vs), 1979 (w), ν(CtO) and
ν
CdO), and 1586 (vs, δNH). 1H NMR (CDCl3): δ 0.58 (m, 2H,
SiCH2), 1.11 (t, 9H, 3J (HH) ) 7 Hz, CH3), 1.56 (quint, 2H,
3J (HH) ) 7 Hz, CH2CH2CH2), 2.17 (t, 4J (HH) ) 2.5 Hz, 1H,
tCH), 3.11 (q, 3J (HH) ) 7 Hz, 2H, NCH2CH2), 3.75 (q, 3J (HH)
3
4
) 7 Hz, 6H, OCH2), 3.90 (dd, J (HH) ) 5.8 Hz, J (HH) ) 2.5
Hz, 2H, tCCH2N), 5.48 (br t, 3J (HH) ) 5.8 Hz, 1H, CH2-
CH2NH), 5.64 (br t, 3J (HH) ) 5.8 Hz, 1H, tCCH2NH). 13C-
{1H} NMR (100.62 MHz, CDCl3): δ 7.62 (s, SiCH2), 18.10 (s,
CH3), 23.26 (s, CH2CH2CH2), 29.92 (tCCH2N), 42.90 (s, NCH2-
CH2), 58.61 (s, OCH2), 70.79 (s, HCt), 81.13 (s, HCtC-), 158.3
(CdO). 29Si{1H} NMR (79.48 MHz, CDCl3): δ -45.5. Anal.
Calcd for C13H26N2O4Si: C, 51.63; H, 8.66; N, 9.26. Found: C,
50.95; H, 8.66; N, 9.24.
1
1740 (vs), ν(CdO). H NMR (300.13 MHz, CDCl3): δ 0.61 (m,
3
2H, SiCH2), 1.21 (t, J (HH) ) 7.5 Hz, 9H, CH3), 1.63 (m, 2H,
CH2CH2CH2), 3.16 (m, 4H, HNCH2CH2 and HC2CH2,), 3.81 (q,
3
3J (HH) ) 7.5 Hz, 6H, OCH2CH3), 4.12 (t, J (HH) ) 6.15 Hz,
2H, OCH2CH2), 4.89 (br, NH), 6.02 (s, 1H, H-C-Co). In
1
Syn th esis of HCtCCH2NHC(O)NHC6H4SMe (L3). A
solution of 4-(methylthio)phenylisocyanate (0.93 mL, 6.65
mmol) in 15 mL of CH2Cl2 was added dropwise to a solution
of propargylamine (0.50 mL, 7.32 mmol) in 15 mL of CH2Cl2
placed at 0 °C. The solution was stirred at room temperature
overnight, and the product was obtained quantitatively as a
white powder that is scarcely soluble in CH2Cl2 (1.46 g, 6.65
mmol). IR (KBr, cm-1): 3320 (s, ν≡CH), 1629 (vs, νCdO) and 1586
(vs, δNH). 1H NMR (acetone-d6): δ 2.40 (s, 3H, CH3), 2.61 (t,
4J (HH) ) 2.55 Hz, 1H, tCH), 3.98 (dd, 4J (HH) ) 2.55 Hz,
3J (HH) ) 7 Hz, 2H, CH2N), 6.04 (m, 1H, CH2NH), 7.17 and
7.44 (AA′BB′ spin system, 4H, C6H4), 8.05 (br s, 1H, C6H4NH).
13C{1H} NMR (75.48 MHz, acetone-d6): δ 16.06 (s, CH3), 29.16
(s, tCCH2N), 70.87 (s, HCt), 81.0 (s, HCtC-), 118.92 and
128.24 (2s, CH of C6H4), 131.0 and 138.0 (2s, Cquater of C6H4),
158.0 (s, CdO). Anal. Calcd for C11H12N2OS: C, 59.98; H, 5.49;
N, 12.72; S, 14.55. Found: C, 59.61; H, 5.41; N, 12.83; S, 14.53.
[NEt4][Ru Co3(CO)10{µ4-η2-HC2(CH2)2OC(O)NH(CH2)3Si-
(OEt)3}] (NEt4‚2). P r ocedu r e A: Reaction of [NEt4][Ru Co3-
(CO)12] w ith HCtC(CH2)2OC(O)NH(CH2)3Si(OEt)3. A so-
lution of NEt4‚1 (0.174 g, 0.235 mmol) and L1 (0.092 g, 0.282
mmol) was refluxed in 40 mL of THF for 6 h. The solution
was filtered and the solvent was removed under vacuum.
Violet crystals of NEt4‚2 (0.158 g, 0.157 mmol, 67%) were
obtained by recrystallization of the product from CH2Cl2/
pentane. IR (CH2Cl2, cm-1): 2048 (mw), 2002 (vs), 1970 (sh),
1814 (m) νC≡O, 1720 (m, νCdO). 1H NMR (CDCl3): δ 0.60 (m,
2H, SiCH2), 1.21 (m, 12H, NCH2CH3), 1.33 (m, 9H, OCH2CH3),
1.54 (m, 2H, CH2CH2CH2), 2.74 (m, 2H, HC2CH2), 3.20 (m,
10H, NCH2CH3 and HNCH2), 3.90 (m, 8H, OCH2CH3 and
CH2CH2O), 4.81 (br, NH), 8.27 (br s, 0.40H, HC2 of one isomer),
8.74 (br s, 0.60H, HC2 of the other isomer). Anal. Calcd for
benzene-d6, the H NMR signals for HNCH2CH2 and HC2CH2
were separated: 2.74 (HC2CH2), 3.16 (HNCH2CH2).
P r oced u r e B: Rea ction of [Co2(CO)6{µ2-η2-HC2(CH2)2-
OH}] (5) (see below ) w ith OCN(CH 2)3Si(OEt)3. Syn th esis
of [Co2(CO)6{µ2-η2-HC2(CH2)2OH}] (5). A solution of [Co2-
(CO)8] (0.325 g, 0.954 mmol) in 25 mL of CH2Cl2 and 3-butyn-
1-ol (0.079 mL, 1.05 mmol) was stirred at room temperature
for 2 h. Completion of the reaction was revealed from TLC by
the disappearance of [Co2(CO)8]. The solvent was then removed
under vacuum. Extraction with hexane afforded red viscous
compound 5 (0.304 g, 0.854 mmol, 89%). IR (hexane, ν(CO),
cm-1): 2098 (vs), 2053 (vs), 2029 (vs), 1980 (w). 1H NMR
(CDCl3): δ 1.58 (br, OH), 3.11 (t, 3J (HH) ) 6.5 Hz, 2H,
HC2CH2), 3.90 (m, 2H, OCH2), 6.02 (s, 1H, H-C-Co).
To a solution of 5 (0.092 g, 0.258 mmol) was then added
dropwise 3-(triethoxysilyl)propylisocyanate (0.071 mL, 0.284
mmol). The solution was stirred at room temperature for 11
h. Completion of the reaction was revealed from TLC by the
disappearance of 5 (eluent CH2Cl2). The solvent was removed
under vacuum. Extraction with hexane afforded red viscous
compound 4 (0.144 g, 0.240 mmol, 93%).
Syn th esis of [NEt4][Ru Co3(CO)10{µ4-η2-HC2CH2NHC-
(O)NH(CH2)3Si(OEt)3}] (NEt4‚6). P r oced u r e A: Rea ction
of [NE t4][R u Co3(CO)12
]
w it h H CtCCH 2NH C(O)NH -
(CH2)3Si(OEt)3. A solution of NEt4‚1 (0.253 g, 0.341 mmol)
and L2 (0.114 g, 0.377 mmol) was refluxed in 50 mL of THF
for 6 h. The solution was filtered and the solvent was removed
under reduced pressure. The product was recrystallized twice
from CH2Cl2/pentane to afford a violet powder of NEt4‚6 (0.277
g, 0.279 mmol, 82%). IR (CH2Cl2, ν(CO), cm-1): 2050 (m), 2005
1
(vs), 1970 (s), 1820 (m), 1671 (m, CdO). H NMR (CDCl3): δ
0.63 (m, 2H, SiCH2), 1.22 (m, 21H, OCH2CH3 and NCH2CH3),
1.60 (m, 2H, CH2CH2CH2), 3.13 (m, 2H, HNCH2CH2), 3.8 (m,
16H, OCH2CH3, NCH2CH3 and HNCH2C2H), 4.41 (m, 1H, NH),
4.64 (m, 1H, NH), 8.24 (br s, 0.16H, HC2- of one isomer), 8.67
(br s, 0.84H, HC2- of the second isomer). Anal. Calcd for
C
32H47Co3N2O15RuSi: C, 38.22; H, 4.71; N, 2.79. Found: C,
37.59; H, 4.55; N, 2.73.
P r oced u r e B: Rea ction of [NEt4][Ru Co3(CO)10(µ4-η2-
HC2(CH2)2OH)] (NEt4‚3) (see below ) w ith OCN(CH2)3Si-
(OEt)3. To a solution of NEt4‚3 (0.100 g, 0.132 mmol) in 15
mL CH2Cl2 was added dropwise 3-(triethoxysilyl)propylisocy-
C
31H46Co3N3O14RuSi-2CH2Cl2: C, 34.15; H, 4.34; N, 3.62.
Found: C, 33.85; H, 4.43; N, 3.99.

Routes to Ruthenium-Cobalt Clusters
Organometallics, Vol. 22, No. 13, 2003 2693
P r oced u r e B: Rea ction of [NEt4][Ru Co3(CO)10(µ4-η2-
HC2CH 2NH 2)] w it h OCN(CH 2)3Si(OE t )3. To a solution of
NEt4‚8, prepared by reaction of NEt4‚1 (0.140 g, 0.188 mmol)
with propargylamine (0.052 mL, 0.756 mmol) in 35 mL of CH2-
Cl2 at 0 °C, was added dropwise 0.053 mL (0.215 mmol) of
3-(triethoxysilyl)propylisocyanate. The solution was stirred at
room temperature for 24 h, filtered, and concentrated, and the
product was recrystallized from CH2Cl2/hexane to give NEt4‚
6 (0.069 g, 0.070 mmol, 37% based on NEt4‚1). When this
procedure was followed, the ratio between isomers 6a and 6b
was 1:2.
Syn th esis of [NEt4][Ru Co3(CO)10{µ4-η2-HC2CH2NHC-
(O)NHC6H4SMe}] (NEt4‚7). P r oced u r e A: Rea ction of
[NEt4][Ru Co3(CO)12] with HCtCCH2NHC(O)NHC6H4SMe.
A solution of NEt4‚1 (0.146 g, 0.197 mmol) and L3 (0.173 g,
0.787 mmol) was refluxed in 35 mL of THF for 5 h. After
filtration through Celite, evaporation to dryness, extraction
of the product with CH2Cl2, and recrystallization from CH2-
Cl2/hexane afforded NEt4‚7 (0.168 g, 0.185 mmol, 94%) as a
violet powder. IR (CH2Cl2, ν(CO), cm-1): 2051 (m), 2006 (vs),
1972 (s), 1820 (m), 1702 (m, νCdO). 1H NMR (acetone-d6): δ
1.32 (m, 12H, CH2CH3), 2.39 (s, 3H, SCH3), 3.34 (m, 8H, CH2-
CH3), 3.91 (s, 2H, CH2NH), 5.45 (m, 1H, CH2NH), 5.60 (m,
1H, C6H4NH), 7.16 and 7.42 (AA′BB′ spin system, 4H, C6H4),
8.08 (br s, 0.33H, HC2- of one isomer), 8.75 (br s, 0.66H, HC2-
of the second isomer). Anal. Calcd for C33H32Co3N3O11RuS: C,
41.44; H, 3.37; N, 4.39; S, 3.35. Found: C, 41.74; H, 3.84; N,
4.76; S, 3.84.
room temperature. After being stirred for 2 h, the solution was
filtered through Celite and the solvent was removed under
reduced pressure. The product was extracted with CH2Cl2/
hexane (80:20), and the solution was concentrated and placed
at -20 °C for 1 week to give orange microcrystals (0.177 g,
0.41 mmol, 65%). IR (CH2Cl2, ν(CO), cm-1): 2095 (s), 2055 (vs),
2026 (vs), 1676 (m, νCdO). 1H NMR (CDCl3): δ 2.45 (s, 3H, CH3),
4.59 (d, 3J (HH) ) 6.26 Hz, 2H, CH2N), 5.08 (br t, 3J (HH) )
6.26 Hz, 1H, CH2NH), 6.07 (s, 1H, HC-Co), 6.38 (br s, 1H,
C6H4NH), 7.23 (m, 4H, C6H4). Anal. Calcd for C17H12Co2N2-
O7S: C, 40.34; H, 2.39; N, 5.53; S, 6.33. Found: C, 40.41; H,
2.39; N, 5.47; S, 6.05.
X-r a y Str u ctu r a l An a lysis of [NEt4][Ru Co3(CO)10(µ4-η2-
HC2(CH2)2OC(O)NH(CH2)3Si(OEt)3] (NEt4‚2) a n d [Co2-
(CO)6{µ2-η2-HC2CH2NHC(O)NH(CH2)3Si(OEt)3}] (9). Single
crystals were mounted on a Nonius Kappa-CCD area detector
diffractometer (Mo KR, λ ) 0.71073 Å). The complete condi-
tions of data collection (Denzo software) and structure refine-
ments are given below. The cell parameters were determined
from reflections taken from one set of 10 frames (1.0° steps in
phi angle), each at 20 s exposure. The structures were solved
using direct methods (SIR97) and refined against F2 using the
SHELXL97 software.14,15 The absorption was corrected empiri-
cally [with Sortav]. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were generated according to
stereochemistry and refined using a riding model in SHELXL97.
Crystal data and structure refinement details for NEt4‚2:
C
32H47Co3N2O15RuSi, M ) 1005.67, violet crystals, triclinic,
P r oced u r e B: Rea ction of [NEt4][Ru Co3(CO)10(µ4-η2-
HC2CH2NH2)] w ith OCNC6H4SMe. To a CH2Cl2 solution of
NEt4‚8 prepared by reaction of NEt4‚1 (0.111 g, 0.150 mmol)
with propargylamine (0.041 mL, 0.6 mmol) was added drop-
wise at 0 °C 0.15 mmol (0.021 mL) of OCNC6H4SMe. After
stirring for 24 h at room temperature, the solution was filtered
through Celite, concentrated, and recrystallized from CH2Cl2/
hexane to give violet crystals of NEt4‚7 (0.057 g, 0.063 mmol,
42% based on NEt4‚1).
space group P1h, a ) 7.501(2) Å, b ) 13.762(2) Å, c ) 21.544(2)
Å, R ) 97.07(5)°, â ) 93.91(5)°, γ ) 97.82(5)°, V ) 2178.4(7)
Å3, Z ) 2, Fcalcd ) 1.533 g cm-3, µ(Mo KR) ) 1.552 mm-1
.
Intensity measurements were performed by ω-2θ scans in the
range 5.18° < 2θ < 60.24° at 173 K; 81 459 independent
2
reflections with 5324 having I > 2σ(I), F refinement, 446
parameters, R1 ) 0.1156, wR2 ) 0.1530 and GOF ) 0.965.
CCDC 204010.
Crystal data and structure refinement details for 9: C19H26
-
Co2N2O10Si, M ) 588.37 g mol-1, red crystal, monoclinic, space
groupe P21/a, a ) 9.099(3) Å, b ) 19.989(5) Å, c ) 14.404(4)
Å, â ) 93.20(2)°, Z ) 4, Fcalcd ) 1.494 g cm-3, µ(Mo KR) ) 1.365
mm-1; a total of 22 545 reflections. Intensity measurements
were performed by ω-2θ scans in the range 2.46° < θ < 30.05°
at 173 K; 7620 independent reflections with 2753 having I >
2σ(I), F 2 refinement, 272 parameters, R1 ) 0.010; wR2 ) 0.020
and GOF ) 1.145. Owing to the large thermal parameters of
the atoms in the group -Si(OEt)3 (thermal motion and/or
disorder), the C-C and C-O distances have been fixed at
values of 1.5 and 1.35 Å, respectively. CCDC 197184.
Additional material has also been deposited with the
Cambridge Crystallographic Data Centre as Supplementary
Publication Nos. CCDC-197184 & 204010. Copies of the data
can be obtained free of charge on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: (+44)1223-336-
033; e-mail: deposit@ccdc.
Syn t h esis of [NE t4][R u Co3(CO)10(µ4-η2-H C2CH 2NH 2)]
(NEt4‚8). Propargylamine (1.286 mmol, 0.088 mL) was added
to a solution of [NEt4][RuCo3(CO)12] (0.238 g, 0.321 mmol) in
50 mL of THF. The mixture was heated under reflux for 5 h.
After cooling, the solution was filtered and the solvent and
the propargylamine in excess were evaporated under vacuum.
Extraction with CH2Cl2 afforded NEt4‚8 (0.210 g, 0.282 mmol,
88%). This cluster decomposes even under N2 and should be
used immediately. IR (CH2Cl2, ν(CO), cm-1): 2048 (m), 2002
(vs), 1969 (s), 1889 (m, Co(CO)4- resulting from decomposition),
1
1819 (m). H NMR (CD2Cl2): δ 1.32 (m, 12H, CH3), 1.67 (m,
2H, NH2), 2.33 (m, 2H, CH2NH2), 3.20 (m, 8H, NCH2CH3), 8.41
(br s, 0.33H, HC2) of one isomer), 8.72 (br s, 0.66H, HC2 of the
second isomer).
Syn th esis of [Co2(CO)6{µ2-η2-HC2CH2NHC(O)NH(CH2)3-
Si(OEt)3}] (9). A mixture of [Co2(CO)8] (0.350 g, 1.028 mmol)
and L2 (0.342 g, 1.131 mmol) in 35 mL of CH2Cl2 was allowed
to react at room temperature for 2 h. A color change from
brown to red was observed, and monitoring by TLC showed
the disappearance of the starting complex. After filtration, the
solvent was removed and the product was extracted with a
mixture of hexane/CH2Cl2 (90:10) and placed at -20 °C to give
red prismatic crystals (0.54 g, 0.918 mmol, 90%). IR (CH2Cl2,
ν(CO), cm-1): 2094 (vs), 2052 (vs), 2026 (vs), 1679 (m, νCdO).
Ack n ow led gm en t. We are grateful to the CNRS,
the Universite´ Louis Pasteur Strasbourg, and the Mini-
ste`re de la Recherche (Paris) for financial support. This
project was also supported by the Fonds International
de Coope´ration Universitaire-FICU (AUPELF-UREF,
Agence Universitaire de la Francophonie).
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates (S-1, S-5), thermal parameters (S-2, S-6), bond
distances (S-3, S-7), and angles (S-4, S-8) for NEt4‚2 and 9,
respectively. This material is available free of charge via the
Internet at http://pubs.acs.org.
3
1H NMR (CDCl3): δ 0.62 (m, SiCH2), 1.21 (t, J (HH) ) 7 Hz,
9H, CH3), 1.61 (quint, 3J (HH) ) 7.4 Hz, 2H, CH2CH2CH2), 3.16
(q, 3J (HH) ) 6.82 Hz, 2H, NCH2CH2), 3.82 (q, 3J (HH) ) 7 Hz,
3
6H, OCH2), 4.54 (d, J (HH) ) 6 Hz, 2H, tCCH2N), 4.63 (br t,
3
3J (HH) ≈ 6 Hz, 1H, NH), 4.76 (br t, J (HH) ≈ 6 Hz, 1H, NH),
6.06 (s, 1H, HC-Co). Anal. Calcd for C19H26Co2N2O10Si: C,
38.79; H,4.45; N, 4.76, Found: C, 38.49; H, 4.30; N,4.61.
Syn th esis of [Co2(CO)6{µ2-η2-HC2CH2NHC(O)NHC6H4-
SMe)}] (10). The ligand L3 (0.152 g, 0.688 mmol) was reacted
with [Co2(CO)8] (0.190 g, 0.555 mmol) in 30 mL of CH2Cl2 at
OM020965M
(14) Kappa CCD Operation Manual; Nonius B.V.: Delft, The
Netherlands, 1997.
(15) Sheldrick, G. M. SHELXL97, Program for the refinement of
crystal structures; University of Gottingen: Germany, 1997.