Parallel approaches to mono- and bis-propargylic activation via Co2(CO)8 and [Ru3(μ-Cl)(CO)10]-

Article abstract of DOI:10.1021/om010568w

Butyne derivatives CH₃C≡CCH₂X and XCH₂C≡CCH₂X (X = hydroxy, acetoxy, tosyloxy) were reacted with Co₂(CO)₈ and [PPN][Ru₃(μ-Cl)(CO)₁₀]. Whereas dissociation of hydroxy and acetoxy groups from the cluster-bound mono-oxypropargylic ligands CH₃C≡CCH₂X requires the assistance of an acid, spontaneous dissociation occurs with a tosyloxy group. For cobalt, this produces the ether complex {Co₂(CO)₆}₂(μ-CH₃C≡CCH ₂OCH₂C≡CCH₃). For ruthenium, stepwise propargylic activation affords the allenyl complex Ru₃(μ-Cl)(μ-η³-CH₃CCCH₂)(C O)₉. The elusive allenylium cobalt intermediate [Co₂(μ-η³-CH₃CCCH₂)(CO)₆ ]+ was optimized at the B3PW91/6-31G* level of theory. Analyses of frontier orbitals, Mulliken charges, and Fukui indices reveal that the ruthenium complex is less electrophilic than the cobalt complex and that soft nucleophiles should react at metal centers in both complexes. This provides a rationale for the known reactivity of Nicholas' cobalt complexes. It is also consistent with the observed reactivity of a hydride with the ruthenium complex, which takes place at the metal, followed by H transfer to the propargylic carbon. With the bisoxypropargylic ligands, the complexes Co₂(μ-XCH₂C=CCH₂X)(CO)₆ and [Ru₃(μ-Cl)(μ-XCH₂C≡CCH₂X)(CO)₉ ]^- (X = OH, OAc) were also prepared. Protonation of the latter yields the neutral allenyl species Ru₃(μ-Cl)(μ-η³-XCH₂CCCH₂)( CO)₉. Again, the specific behavior of the bis(tosyloxy) ligand (X = OTs) was observed. While the cobalt complex Co₂(μ-η²-TsOCH₂CCCH₂OTs)(CO) ₆ turned out to be relatively stable, a butatriene-type ruthenium complex was detected by in situ 2D ¹H-¹³C NMR. The target cationic butatriene complex [Ru₃(μCl)(μ-η⁴-CH₂CCCH₂)(C O)₉][BF₄] was finally obtained by protonation of the hydroxyallenyl complex Ru₃(μ-Cl)(μ-η³-HOCH₂CCCH₂) (CO)₉.

Full text of DOI:10.1021/om010568w

Organometallics 2002, 21, 871-883
871
P a r a llel Ap p r oa ch es to Mon o- a n d Bis-P r op a r gylic
Activa tion via Co2(CO)8 a n d [Ru 3(µ-Cl)(CO)10]-
Miche`le Soleilhavoup, Catherine Saccavini, Christine Lepetit, Guy Lavigne,
Luc Maurette, Bruno Donnadieu, and Remi Chauvin*
Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne,
31077 Toulouse Cedex 4, France
Received J une 26, 2001
Butyne derivatives CH3CtCCH2X and XCH2CtCCH2X (X ) hydroxy, acetoxy, tosyloxy)
were reacted with Co2(CO)8 and [PPN][Ru3(µ-Cl)(CO)10]. Whereas dissociation of hydroxy
and acetoxy groups from the cluster-bound mono-oxypropargylic ligands CH3CtCCH2X
requires the assistance of an acid, spontaneous dissociation occurs with a tosyloxy group.
For cobalt, this produces the ether complex {Co2(CO)6}2(µ-CH3CtCCH2OCH2CtCCH3). For
ruthenium, stepwise propargylic activation affords the allenyl complex Ru3(µ-Cl)(µ-η3-CH3-
CCCH2)(CO)9. The elusive allenylium cobalt intermediate [Co2(µ-η3-CH3CCCH2)(CO)6]+ was
optimized at the B3PW91/6-31G* level of theory. Analyses of frontier orbitals, Mulliken
charges, and Fukui indices reveal that the ruthenium complex is less electrophilic than the
cobalt complex and that soft nucleophiles should react at metal centers in both complexes.
This provides a rationale for the known reactivity of Nicholas’ cobalt complexes. It is also
consistent with the observed reactivity of a hydride with the ruthenium complex, which
takes place at the metal, followed by H transfer to the propargylic carbon. With the bis-
oxypropargylic ligands, the complexes Co2(µ-XCH2CtCCH2X)(CO)6 and [Ru3(µ-Cl)(µ-XCH2-
CtCCH2X)(CO)9]- (X ) OH, OAc) were also prepared. Protonation of the latter yields the
neutral allenyl species Ru3(µ-Cl)(µ-η3-XCH2CCCH2)(CO)9. Again, the specific behavior of the
bis(tosyloxy) ligand (X ) OTs) was observed. While the cobalt complex Co2(µ-η2-TsOCH2-
CCCH2OTs)(CO)6 turned out to be relatively stable, a butatriene-type ruthenium complex
1
was detected by in situ 2D H-13C NMR. The target cationic butatriene complex [Ru3(µ-
Cl)(µ-η4-CH2CCCH2)(CO)9][BF4] was finally obtained by protonation of the hydroxyallenyl
complex Ru3(µ-Cl)(µ-η3-HOCH2CCCH2)(CO)9.
In tr od u ction
carbenium salts, due to preexisting polarization of the
propargylic Cδ+-Oδ-Tf bond. Though the tosylate group
might be expected to exhibit a pivotal behavior, the
corresponding Nicholas-type complexes have not been
intercepted.
Due to their extensive practical applications in or-
ganic synthesis, alkyne-cobalt(0) complexes have re-
ceived considerable attention. Indeed, the dicobalt hexac-
arbonyl unit is involved as a promoter in the Pauson-
Khand reaction1 and as a versatile protecting group for
triple bonds,2 enabling in particular the activation of
Nicholas-type propargylic psuedo-SN1 reactions.3,4 Within
the latter prospect, many η2-propargylic halide, alcohol,
ether, and ester complexes Co2(µ-η2-RCCCH2X)(CO)6
(Ia ) have been described (Scheme 1).5 Their subsequent
conversion into η3-propargylic carbenium complexes
[Co2(µ-η3-RCCCH2)(CO)6]+ (Ib) depends on the nature
of the leaving group: the dissociation of acetates
requires the assistance of an acid,6 whereas related
triflate complexes exist exclusively as η3-propargylic
To date, the bimetallic units Co2(CO)4(dppm), Mo2-
Cp2(CO)4, and CoMoCp(CO)5 remain the main general
alternatives to the use of the Co2(CO)6 unit for propar-
gylic activation.7 Keeping in mind recent observations
that a growing number of cobalt-specific reactions of
alkynes (i.e. the Pauson-Khand reaction) are now
catalyzed by Ru3(CO)12,8 we became interested in ex-
amining the ability of ruthenium complexes to activate
Nicholas-type propargylic substitutions. The well-
established “halide promoted”9 reaction of alkynes with
Ru3(CO)12 appeared as a rational synthetic route to the
desired trinuclear complexes [Ru3(µ-Cl)-η2-RCCCH2X)-
(CO)9]- (IIa ) and Ru3(µ-Cl)(µ-η3-RCCCH2)(CO)9 (IIb)
(Scheme 1). The comparative study is carried out in both
* To whom correspondence should be addressed. Tel: 33 (0)5 61 33
31 13. Fax: 33 (0)5 61 55 30 03. E-mail: chauvin@lcc-toulouse.fr.
(1) Shore, N. E. Chem. Rev. 1988, 88, 1081-1119.
(2) Nicholas, K. M.; Pettit, R. Tetrahedron Lett. 1971, 37, 3475-
3478.
(3) Nicholas K. M. Acc. Chem. Res. 1987, 20, 207-214.
(4) Huhn, O.; Rau, D.; Mayr, H. J . Am. Chem. Soc. 1998, 120, 900-
907.
(7) (a) McGlinchey, M. J .; Girard, L.; Ruffolo, R. Coord. Chem. Rev.
1995, 143, 331-381. (b) Mu¨ller, T. J . J . Eur. J . Inorg. Chem. 2001,
2021.
(8) Kondo, T.; Suzuki, N.; Okada, T.; Mitsudo, T. J . Am. Chem. Soc.
1997, 119, 6187-6188.
(5) Went, M. J . Adv. Organomet. Chem. 1997, 41, 69-125.
(6) When the metal counterpart of the nucleophile is sufficiently
Lewis acidic (aluminum), the use of an auxiliary acid can be avoided:
Padmanabhan, S.; Nicholas, K. M. Tetrahedon Lett. 1983, 24, 2239.
(9) (a) Rivomanana, S.; Lavigne, G.; Lugan, N.; Bonnet, J .-J .; Yanez,
R. J . Am. Chem. Soc. 1989, 111, 8959-8960. (b) Rivomanana, S.;
Lavigne, G.; Lugan, N.; Bonnet, J .-J . J . Am. Chem. Soc. 1990, 112,
8607-8609. (c) Lavigne, G. Eur. J . Inorg. Chem. 1999, 917-930.
10.1021/om010568w CCC: $22.00 © 2002 American Chemical Society
Publication on Web 02/01/2002

872 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
Sch em e 1. An a logy betw een P r op a r gyl Tr ica r bon ylcoba lt a n d Tr ica r bon ylr u th en iu m Clu ster sa
a
X ) oxy substituent. Note: the dotted lines represent the average of the two Lewis resonance structures with a localized
minus charge and a formal 18-electron count for all the Ru atoms: [Ru]--Clf[Ru] T [Ru]rCl-[Ru]-.
Sch em e 2. P ecu lia r Rea ctivity of 1-(Tosyloxy)bu t-2-yn e (1a ) w ith Co2(CO)6
a
[Co] ) Co(CO)3.
mono- and bis-propargylic series, using the alkyne
prototypes CH3CtCCH2X and XCH2CtCCH2X, respec-
tively, with X ) hydroxy, acetoxy, tosyloxy.
Resu lts a n d Discu ssion
Mon op r op a r gylic Activa tion . (1) Exp er im en ta l
Resu lts in th e Coba lt Ser ies. Whereas propargylic
ethers, alcohols, and acetates readily react with Co2-
(CO)8 to afford the corresponding neutral Nicholas-type
complexes, the corresponding complex 2 (in either the
associated form Co2(µ-η2-CH3CCCH2OTs)(CO)6 (2a ) or
dissociated form [Co2(µ-η3-CH3CCCH2)(CO)6][OTs] (2b))
could not be isolated from the reaction of 1-(tosyloxy)-
but-2-yne (1a ) with Co2(CO)8. Instead, the dibutynyl
ether complex 3 was isolated in 79% yield (Scheme 2).
The X-ray crystal structure of complex 3 (Figure 1 and
Table 1) has to be compared with that of the isostruc-
tural alkyne complex {Co2(CO)6}2(µ-HCtCCH2OCH2Ct
CH), previously prepared by the classical route via
reaction of dipropynyl ether with Co2(CO)8.10 The η2-
CtCH bonds of the latter complex were seen to be quite
long. Despite the larger steric demand of the methyl
F igu r e 1. X-ray crystal structure of complex 3. Selected
bond distances in Å: Co(1)-Co(2) ) 2.4654(18); Co(3)-
Co(4) ) 2.4602(19); Co(1)-C(2) ) 1.934(9); Co(1)-C(1) )
1.963(9); Co(2)-C(2) ) 1.924(10); Co(2)-C(1) ) 1.943(9);
Co(3)-C(6) ) 1.927(10); Co(3)-C(5) ) 1.943(9); Co(4)-C(5)
)
1.931(10); Co(4)-C(6)
)
1.946(10); C(1)-C(2)
)
1.284(13); C(5)-C(6) ) 1.297(13). Selected bond angles in
deg: C(1)-C(2)-C(3)
)
141.5(9); C(2)-C(1)-C(8) )
145.4(10); C(6)-C(5)-C(4) ) 141.1(10); C(5)-C(6)-C(7) )
141.3(10); C(4)-O(1)-C(3) ) 107.9(7).
of the Co2(CO)6 units is thus lowered by a long-range
inductive effect of the doubly propargylic oxygen atom.
The intermediacy of a more or less dissociated form
of complex 2 en route to 3 can be reasonably expected.
In the absence of any detectable trace of but-2-yn-1-ol
(which might result from incidental hydrolysis),11 the
formation of ether 3 under neutral conditions reveals a
peculiar reactivity of complex 2 (Scheme 2).
substituents, the η2-CtCMe bond lengths in
3
(1.284(13) and 1.297(13) Å) tend to be slightly shorter
than the corresponding η2-CtCH bond lengths in the
homologous bis-terminal alkyne complex (1.308(6) and
1.316(6) Å) and markedly shorter than classical acety-
lenic η2-CtC bonds in related cobalt complexes (in the
range 1.33-1.36 Å).10 The electron-withdrawing effect
(2) E xp er im en t a l R esu lt s in t h e R u t h en iu m
(10) Chen, X.-N.; Zhang, J .; Wu, S.-L.; Yin, Y.-Q.; Wang, W.-L.; Sun,
J . J . Chem. Soc., Dalton Trans. 1999, 1987-1991.
Ser ies. It was previously noted9c that the reaction of

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 873
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for Com p lexes 3, 5b, a n d 8a a
3
5b
8a
formula
fw
temp (K)
C21H10Co4O13 C13H5ClO9Ru3 C14H10O10Co2
705.74
180(2)
643.83
160(2)
0.71073
triclinic
P1h
456.08
298(2)
0.71073
triclinic
P1h
wavelength (Å) 0.71073
cryst syst
space group
a (Å)
b (Å)
c (Å)
triclinic
P1h
7.515(2)
10.637(2)
16.180(3)
94.56(3)
94.54(3)
92.04(3)
1284.1(5)
2
9.443(2)
9.501(2)
10.194(2)
77.43(3)
87.03(3)
86.13(3)
890.0(3)
2
9.222(2)
73.30(3)
12.697(3)
73.30(3)
87.57(3)
62.87(3)
927.9(4)
2
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
F (g cm-3
)
1.369
2.403
1.632
abs coeff µ
(mm-1
F(000)
0.729
2.706
1.835
)
534
608
456
F igu r e 2. X-ray crystal structure of complex 5b. Selected
bond distances in Å: Ru(1)-Cl(1) ) 2.4769(10); Ru(1)-
Ru(2) ) 2.7931(7); Ru(2)-Ru(3) ) 2.8487(10); Ru(3)-Cl-
(1) ) 2.4290(9); Ru(1)-C(12) ) 2.076(3); Ru(2)-C(12) )
2.253(2); Ru(2)-C(11) ) 2.095(2); Ru(3)-C(11) ) 2.263 (3);
Ru(3)-C(10) ) 2.277(3); C(12)-C(11) ) 1.383 (4); C(11)-
C(10) ) 1.380(4). Selected bond angles in deg: C(11)-
C(10)-Ru(3) ) 71.77(15); C(10)-C(11)-C(12) ) 142.8(2);
C(11)-C(12)-C(13) ) 116.8(2); C(11)-C(12)-Ru(1) )
117.70(18).
θ range (deg)
1.92-23.25
2.05-25.96
2.50-25.99
-11 e h e 11
-11 e k e 11
-15 e l e 15
index ranges
-8 e h e 8
-11 e h e 11
-11 e k e 11 -11 e k e 11
-17 e l e 17 -12 e l e 12
no. of rflns
collected
unique
R(int)
completeness
(%)
no. of data
restraints
params
9506
3500
0.1061
8652
3208
0.0411
8486
3373
0.0626
92.6 (to 2θ )
25.99°)
3373
94.8 (to 2θ ) 92.2 (to 2θ )
23.25°) 25.96°)
3500 3208
0
0
236
0
237
336
0.0497
Upon protonation of 4a by HBF4 in THF, the neutral
allenyl complex 4b was produced.9c,13
R1 (I > 2σ(I))
0.0233
0.0582
0.0253
0.0593
0.626
-0.678
0.0395
0.0920
0.0699
0.1052
0.319
wR2 (I > 2σ(I)) 0.0869
When the analogous reaction was performed with
1-(tosyloxy)but-2-yne (1a ), the expected intermediate
[Ru3(µ-Cl)(µ-η2-CH3CCCH2OTs)(CO)9]- (5a) (correspond-
ing to 2a in the cobalt series) was not detected by IR,
whereas the reaction readily proceeded toward the
formation of the neutral allenyl complex Ru3(µ-Cl)(µ-
η3-CH3CCCH2)(CO)9 (5b), isolated in 68% yield (Scheme
4). This provided a hint that the reaction pathway might
involve in that case the η1-propargylic intermediate 5c.14
The latter would simply result from an SN2-type sub-
stitution of the tosylate group by the anionic nucleophile
[Ru3(µ-Cl)(CO)10]- generated in situ (Scheme 4).
The X-ray crystal structure of 5b is shown in Figure
2. The propargylic C10-Ru3 bond distance is ca. 2.28
Å: i.e., merely 13% longer than a pure covalent σ bond
(theoretical distance rcov(Ru) + rcov(C) ) 1.25 + 0.77 )
2.02 Å), revealing a strong σ-alkyl character of the
complex.
(3) Com p a r a tive Th eor etica l An a lysis of Allen yl
Com p lexes 2b a n d 5b. To allow comparison of the
related allenyl complex Ru3(µ-Cl)(µ-η3-CH3CCCH2)(CO)9
(5b) (stable) with the allenylium complex 2b (elusive),
the geometry of the latter was fully optimized at the
B3PW91/6-31G* level (Figure 3). Indeed, let us remind
the reader that, apart from Melikyan’s report of a doubly
[Co2(CO)6] complexed tris-propargylic cation,15 no X-ray
diffraction data are available for standard [Co2(CO)6]-
mono-propargylium complexes of type Ia . The results
indicate a similar geometry of the ligand in both the
crystal structure of 5b and the DFT-optimized structure
R1 (all data)
0.1321
0.1103
0.462
wR2 (all data)
∆Fmax (e Å-3
)
)
∆Fmin (e Å-3
-0.351
-0.420
a
Refinement method: full-matrix least squares on F2.
Sch em e 3. Syn th esis of P r op a r gylic Com p lexes 4a
a n d 4ba
a
[Ru] ) Ru(CO)3.
propargyl alcohol with Ru3(CO)12 in the presence of bis-
(triphenylphosphine)nitrogen(1+) chloride ([PPN][Cl])
proceeds as established earlier for terminal and internal
alkynes, producing the anionic propargylic alcohol tr-
iruthenate complex 4a (Scheme 3). As noted by Basolo,12
the observed kinetics for complexation of alkynols are
particularly fast, since the protic character of the ligand
itself facilitates a transient opening of the Ru-Cl bond.
(11) Complex 3 could result from partial hydrolysis of 2 and reaction
of the alcohol with another molecule of 2. However, the absence of
unreacted alcohol in the crude product (NMR) would result from an
extraordinary coincidence (the amount of water would be exactly half
the amount of 2). It may also be proposed that 2 is so reactive that it
even reacts with an oxygen atom of the propargyl tosyl ether 1a , the
nucleophilicity of which is generally negligible.
(13) Lavigne, G. Unpublished results.
(14) Cheng, M.-H.; Shu, H.-G.; Lee, G.-H.; Peng, S.-M.; Liu, R.-S.
Organometallics 1993, 12, 108-115.
(15) Melikyan, G. G.; Bright, S.; Monroe, T.; Hardcastle, K. I.;
Ciurash, J . Angew. Chem., Int. Ed. Engl. 1998, 37, 161-164.
(12) (a) Shen, J .-K.; Basolo, F. Gazz. Chim. Ital. 1994, 124, 439. (b)
Basolo, F. Private communication.

874 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
Sch em e 4. Syn th esis of th e Allen yl Com p lex 5b th r ou gh th e Lik ely In ter m ed ia te 5c14 a
a
[Ru] ) Ru(CO)3.
Ta ble 2. Mu llik en Atom ic Ch a r ges a n d
Nu cleop h ilic F u k u i In d ices for Com p lexes 2b a n d
5ba
Mulliken charges
Fukui indices
local softness
atom
2b
5b
2b
5b
2b
5b
CR
MR
Câ
Mâ
Cγ
Mγ
CH3
Cl
-0.34
-0.95
+0.13
-0.79
+0.12
-0.46
-0.24
-0.05
-0.23
-0.12
-0.23
-0.53
-0.16
+0.007
0.00 +0.023
0.000
+0.128 +0.14 +0.456 +0.561
+0.047 +0.01 +0.169 +0.040
+0.047 +0.08 +0.168 +0.321
+0.101
-0.02 +0.077 -0.080
+0.04
0.00 -0.030
+0.03
+0.160
0.000
+0.120
-0.61
-0.009
a
f+ +(A) ) qNb+1e(A) - qNb(A), where Nb + 1e refers to the
Nb
vertical one-electron reduction product of Nb. 2b was calculated
at the B3PW91/6-31G*/DZVP(Co) level, and 5b was calculated at
the B3PW91/6-31G*/DZVP(Ru) level.
Ta ble 3. En er gy Levels (in h a r tr ees) of F r on tier
Or bita ls Ca lcu la ted a t th e 6-31G*/DZVP (Co, Ru )
Level for Com p lexes 2b a n d 5b
F igu r e 3. Calculated structure of complex 2b (B3PW91/
6-31G*). Selected bond distances in Å: Co(1)-Co(2) )
2.470; C(3)-C(4) ) 1.359; C(4)-C(5) ) 1.388; Co(2)-C(5)
) 2.142; C(3)-C(8) ) 1.482. Selected bond angles in deg:
C(3)-C(4)-C(5) ) 134.6; C(4)-C(3)-C(8) ) 134.0; H(6)-
C(5)-H(7) ) 115.2; C(4)-C(5)-H(6) ) 119.9; C(4)-C(5)-
H(7) ) 120.1.
2b
5b
MO
CH2 pz weight energy CH2 pz weight energy
LUMO + 2
LUMO + 1
LUMO
0
+
0
-0.2062
-0.2223
-0.2639
-0.4179
+
0
0
-0.0594
-0.0681
-0.0781
-0.2312
HOMO
0
0
+
of 2b. In particular, the shortest calculated Co‚‚‚CH2
distance is 2.142 Å:16 i.e., 11% longer than the theoreti-
cal higher limit for an apolar pure σ bond, rcov(Co) +
artifact of the DFT nature of the MO’s. Indeed, semi-
empirical ZINDO calculations afford the same qualita-
tive results.18 For the primary propargylium complex
2b, these findings are apparently paradoxical with
respect to EHMO calculations performed on a related
Co2(CO)6-tertiary propargylium complex:19 although
the sum of bond angles around the propargylic CRH2
carbon atom is equal to 355.2°, and thus consistent with
the classical view of sp2 hybridization for CR, the
corresponding pz AO is not found in the LUMO but in
the LUMO + 1, which is 26.1 kcal mol-1 higher in
energy (Table 3). For 5b, the LUMO lies 116.6 kcal
mol-1 higher than that of 2b, suggesting that 5b is
globally less electrophilic than 2b. In a similar way,
however, the CR pz AO does not contribute to the LUMO
of 5b. It does not contribute to the LUMO + 1 either
but exclusively to the LUMO + 2, lying 11.7 kcal mol-1
higher than the LUMO (Figure 4, Table 3).
r
cov(C) ) 1.16 + 0.77 ) 1.93 Å. It is thus as much of a
bonding interaction as that measured for 5b in the
crystalline state. The distortions of the formal C(sp)-
C(sp)-C(sp2) bond angle with respect to 180° in both
5b (37.2°) and 2b (45.4°) are found to be of the same
magnitude, as well.
The electronic properties of 2b and 5b were further
compared from calculations at the B3PW91/6-31G*/
DZVP(M) level (M ) Co, Ru), according to three crite-
ria: frontier orbitals, atomic charges, and Fukui indices.
In the following, heavy atoms of the allenyl complexes
are denoted by the topological sequence: Me-Cγ-Câ-
CRH2-[MR]-[Mâ]-(-[Mγ] for M ) Ru only).
(i) Or bita l An a lysis. The frontier orbitals of 2b and
5b were analyzed, following a current procedure for the
analysis of organometallic reactivity.17 The results tend
to indicate a low reactivity of the propargylic CR atom
in both complexes: the LUMO (which is similar in shape
It is also noteworthy that the significant contributions
of Câ to the LUMO’s of 2b and 5b are reminiscent of
the well-established Câ regioselectivity of nucleophilic
attack at η3-propargylic complexes of group 10 metals.20
2
to the corresponding HOMO) displays high pxy- and dz -
type contributions of the Câ and MR centers, respec-
tively, but no contribution of the propargylic CR center
(Figure 4). This rather unexpected feature is not an
(18) ZINDO, 96.0/4.0.0; Molecular Simulation Inc., Cambridge, U.K.,
1996.
(19) Gruselle, M.; El Hafa, H.; Nokolski, M.; J aouen, G.; Vaisser-
mann, J .; Li, L.; McGlinchey, M. Organometallics 1993, 12, 4917-
4925.
(16) In Melikyan’s tetranuclear tris-propargylium complex, the
shortest measured Co‚‚‚CH+ distance is equal to 2.81 Å.15
(17) See for example: Nelson, D. J .; Li, R.; Brammer, C. J . Am.
Chem. Soc. 2001, 123, 1564-1568.

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 875
F igu r e 4. Lowest unoccupied MO’s for allenyl complexes 2b and 5b at the B3PW91/6-31G*/DZVP(M) level (M ) Co, Ru).
The arrow indicates the formal pz orbital of the sp2-hybridized propargylic CH2 center.
(ii) Atom ic Ch a r ges. A low reactivity of the prop-
argylic CR atom could also be anticipated from Mulliken
population analysis (Table 2). Indeed, the atomic charges
of the propargylic CR and MR (M ) Co, Ru) centers are
unexpectedly negatively charged in both the cationic
complex 2b and the neutral complex 5b. Thus, the
widely accepted “electrophilic” character of CR in 2b
(Nicholas reaction) cannot be rationalized in terms of
simple electronegativity arguments.
(iii) F u k u i In d ices. How do we conciliate the pre-
ceding theoretical analysis with Nicholas’ experimental
results? Reactivity is a two-partner property which
depends not only on the relative electronegativity of the
reactants (“plus likes minus” and conversely) but also
on their relative softness (“hard likes hard” and “soft
likes soft”).21 In the HSAB theory, a molecule is funda-
mentally characterized by both its electronegativity (or
chemical potential) and its softness, denoted as S.
According to Pearson,22 η ) 1/S ≈ I - A ) E(Mq-1) +
E(Mq+1) - 2[E(Mq)], where I and A are the vertical
ionization potential and electron affinity and E is the
molecular electronic energy. Its calculated value at the
6-31G*/DZVP(Co, Ru) level of theory shows that, as
anticipated from qualitative considerations (charge,
In the same manner as global electronegativity is
determined by local (atomic) charges, global softness (S)
can be split into local components: for a given molecule
Mq, the local softness at the atom i is defined as: Si )
fiS, where fi is the Fukui index of the atom i for
nucleophilic, electrophilic, or radical reactivity (see
Computional Methods). This index is becoming a mod-
ern tool to compare the relative reactivity of sites within
a given molecular complex.23 Practically, the Fukui
electrophilic reactivity index fi+ can be estimated by
finite differences of Mulliken charges of atoms i in the
one-electron-oxidized and -reduced structures. High
positive values of fi+ indicate an enhanced reactivity of
the atom i toward soft nucleophiles, while zero or
negative values of fi+ indicate a specific reactivity
toward hard nucleophiles.24
fi+ indices were calculated at relevant atoms of 2b and
5b (Table 3). Their values are in accordance with Parr’s
theory: they roughly vary with the LUMO densities
(Figure 4).21a In particular, regarding soft nucleophiles,
the less electrophilic allenyl carbon center in both of
these complexes should definitely be Cγ and CR. More
precisely, the regioselectivity of soft nucleophiles can be
ranked through local softness values:
metal), 5b is softer than 2b (S(2b) ) 3.558 hartree-1
<
S(5b) ) 4.008 hartree-1). The difference is, however,
rather small and does not a priori rule out the possibility
of extending the reactivity of cationic cobalt complexes
to the analogous neutral ruthenium complexes.
cobalt series:
(SC ) 0.023 hartree-1) CR < Cγ < Câ )
R
Coâ < CoR (SCo ) 0.456)
R
ruthenium series:
(20) (a) Tsuji, J .; Mandai, T., Angew. Chem., Int. Ed. Engl. 1995,
34, 2589-2612. (b) Chen, J .-T. Coord. Chem. Rev. 1999, 190-192,
1143-1168.
(S ) - 0.080 hartree-1) Cγ < CR < Câ < Cl <
Cγ
(21) (a) Parr, R. G.; Yang, W. J . Am. Chem. Soc. 1984, 106, 4049-
4050. (b) Gazquez, J . L.; Mendez, F. J . Phys. Chem. 1994, 98, 4591-
4593. (c) Li, Y.; Evans, J . N. S. J . Am. Chem. Soc. 1995, 117, 7756-
7759. (d) Baekelandt, B. G.; Cedillo, A.; Parr, R. G. J . Chem. Phys.
1995, 103, 8548-8556. (e) De Proft, F.; Martin, J . M. L.; Geerlings, P.
Chem. Phys. Lett. 1996, 256, 400-408.
Ruγ < Ruâ < RuR (SRu ) 0.561 hartree-1
)
R
(23) Chermette, H. Coord. Chem. Rev. 1998, 178-180, 699-721.
(24) Mendez, F.; Gazquez, J . L. J . Am. Chem. Soc. 1994, 116, 9298-
(22) (a) Parr, R. G.; Pearson, R. G. J . Am. Chem. 1983, 102, 7512.
(b) Pearson, R. G. Inorg. Chem. 1988, 27, 734-740.
9301.

876 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
Sch em e 5. Electr op h ilic Rea ctivity of th e Allen yl
Com p lex 5b
Thus, the propargylic metal atom MR is the most
sensitive atom toward soft nucleophiles, whereas the
propargylic carbon atoms CR and Cγ are the most
sensitive atoms toward hard nucleophiles. Moreover, the
local softnesses of CR and MR are of the same order of
magnitude in 2b and 5b. The Co-Ru analogy is
therefore theoretically supported.
This analysis for the cobalt complex 2b has, however,
to be confronted with the well-documented experimental
reactivity of cationic Nicholas-type complexes. The
generally accepted mechanism of this reaction involves
an exo attack of the propargylic carbon atom by the
incoming nucleophile.7,25 It is then noteworthy that most
of the nucleophiles reported to afford the CR-substitution
product are neutral (amines, alcohols, enol ethers, allyl
silanes, ...). Considering that the few reported examples
of anionic nucleophiles such as CH3MgBr have not been
thoroughly examined from a mechanistic point of view,
the nature of the initial site of attack may be ques-
tioned.26 Furthermore, anions are generally regarded
as being softer than neutral species. Thus, according to
the above theoretical results, neutral nucleophiles should
be regarded as hard. On the other hand, these results
suggest that initial attack by anionic nucleophiles
should take place at the metal center.27 A subsequent
transfer to the organic ligand could, however, be envis-
aged. In the following experiments, a hydride was thus
selected as a prototype of potentially transferable
anionic nucleophile.
Bis-P r op a r gylic Activa tion . Unlike substituted
butatrienes, butatriene itself is unstable and undergoes
radical polymerization, revealing
a
formal •CH2-
CtCCH2• biradical character.28 Nevertheless, butatriene
has been long stabilized in neutral transition-metal
complexes such as Fe2(CO)6(C4H4) and Fe2(PPh3)(CO)5-
(C4H4),29 Pushing the challenge further, stabilization of
the corresponding +CH2CtCCH2 dication can be
+
claimed to occur in dicationic complexes such as [Mo2-
Cp2(CO)4(C4H4)]2+ 30
,
[CoMoCp(CO)5(C4H4)]2+ 31
,
and [Co2-
(CO)2(dppm)2(C4H4)]2+ 32
.
Nevertheless, although its ex-
istence is supported by a few examples of double
Nicholas reactions,33 the corresponding [Co2(CO)6-
(C4H4)]2+ complex has not been detected so far.34 This
quest would correspond to a double-propargylic activa-
tion of neutral 1,4-dihalo-35 or 1,4-dioxybut-2-yne com-
plexes Ia into the dicationic limiting form Id (Scheme
6). The access to relevant species in the ruthenium
series considered here would be facilitated, since it
would correspond to the generation of the monocationic
limiting form IId (Scheme 6): namely, to a formal
(4) Rea ction of th e Allen yl Ru th en iu m Com p lex
5b w ith a Hyd r id e Don or . While the reactivity of
cobalt complexes such as 2b has been widely investi-
gated, a preliminary exploration of the reactivity of 5b
was undertaken with K-Selectride as an efficient hy-
dride carrier. The addition of 1 equiv of K-Selectride to
the allenyl complex 5b was found to result in the
consumption of about 50% of the allenyl complex, as
indicated by IR monitoring. Further addition of a second
equivalent of K-Selectride afforded the anion K[Ru3(µ-
H)(µ-MeCCMe)(CO)9] (6a ) in quantitative spectroscopic
yield (Scheme 5). As previously noted for complexes of
the type [Ru3(µ-Cl)(µ-RCCR)(CO)9]-,9a,b nucleophilic at-
tack by a hydride takes place at the metal, resulting in
a facile displacement of the halide. Here, the same
substitution reaction takes place with concomitant
transfer of the hydride from the metal to the carbon
center (reductive elimination), thereby requiring 2 equiv
of K-Selectride. Upon protonation of the anion 6a , the
neutral complex Ru3(µ-H)2(MeCCMe)(CO)9 (6b) is re-
covered. The revealed electrophilic character of the
metal core of 5b is consistent with the above orbital and
Fukui index analysis, which definitely points to the
metal atoms as the softer electrophilic centers (f+(RuR)
) +0.14 > f+(Ruâ) ) +0.08 > f+(Ruγ) ) +0.04).
•
stabilization of the CH2CtCCH2+ monoradical cation.
Let us mention that such a bonding situation of a
substituted-butatriene fragment has been recently ob-
served in neutral triruthenium carbonyl complexes
bearing azavinylidene as an ancillary ligand.36
(28) (a) Schubert, W. M.; Liddicoet, T. H.; Lanka, W. A. J . Am. Chem.
Soc. 1954, 76, 1929-1932. (b) Morris, V. R.; Pollack, S. K. J . Phys.
Chem. B 1998, 102, 5042-5046.
(29) (a) Nakamura, A.; Kim, P. J .; Hagihara, N. J . Organomet.
Chem. 1965, 3, 7-15. (b) J oshi, K. K. J . Chem. Soc. A 1966, 594-597.
(c) Gerlach, J . N.; Wing, R. M.; Ellgen, P. C. Inorg. Chem. 1976, 15,
2959-2964. (c) Bruce, M. Chem. Rev. 1998, 98, 2832 and references
therein.
(30) (a) Reutov, O. A.; Barinov, I. V.; Chertkov, V. A.; Sokolov, V. I.
J . Organomet. Chem. 1985, 297, C25-C29. (b) McClain, M. D.; Hay,
M. S.; Curtis, M. D.; Kampf, J . W. Organometallics 1994, 13, 4377-
4386. [CoMoCp(CO)5(C4H4)]2+
.
(31) Gruselle, M.; Malezieux, B.; Vaissermann, J .; Amouri, H.
Organometallics 1998, 17, 2337-2343.
(32) Bennett, S. C.; Phipps, M. A.; Went, M. J . J . Chem. Soc., Chem.
Commun. 1994, 225-226.
(25) Schreiber, S. L.; Klimas, M. T.; Sammakia, T. J . Am. Chem.
Soc. 1987, 109, 5749-5759.
(26) (a) Padmanabhan, S.; Nicholas, K. M. J . Organomet. Chem.
1981, 212, 115-124. (b), Soleilhavoup, M.; Chauvin, R. Unpublished
results.
(27) Let us note that a NaBH4 hydride is the sole anionic nucleophile
reported to react with in situ formed Nicholas cobalt complexes such
as 2b to afford methyl products: Nicholas, K. M.; Siegel, J . J . Am.
Chem. Soc. 1985, 107, 4999-5001. To be in accord with the present
theoretical analysis, we could propose that a metal attack could occur
first to give a [[Co]H-[Co]-CH2(µ-η2-CtCMe)] intermediate, which
would then undergo reductive elimination.
(33) (a) Gruselle, M.; Philomin, V.; Chaminant, F.; J aouen, G.;
Nicholas, K. M. J . Organomet. Chem. 1990, 399, 317. (b) Takano, S.;
Sugihara, T.; Ogasawara, K. Synlett 1992, 70-72.
(34) Green, J . R. Chem. Commun. 1998, 1751-1752.
(35) The 1,4-dichlorobut-2-yne complex (Ia , X ) Cl) is known:
Getini, G.; Gambino, O.; Rossetti, R.; Sappa, E. J . Organomet. Chem.
1967, 8, 149-154. The 1,4-diiodobut-2-yne complex (Ia , X ) I) is
unknown, although it would be a stabilized form of 1,4-diiodo-2-butyne,
which rapidly izomerizes to 2,3-diiodobutadiene: Wille, F.; Dirr, K.;
Kerber, H. Liebigs Ann. Chem. 1955, 591, 177.
(36) Cabeza, J . A.; Grepioni, F.; Moreno, M.; Riera, V. Organome-
tallics 2000, 19, 5424-5430.

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 877
Sch em e 6. P ossible Reson a n ce Str u ctu r es of Bis-P r op a r gylic Coba lt a n d Ru th en iu m Com p lexes
Sch em e 7. P r ep a r a tion of Dioxy Bis-P r op a r gylic Com p lexesa
a
[Co] ) Co(CO)3.
(1) Coba lt Ser ies. The synthesis of the cobalt car-
bonyl complexes of but-2-yne-1,4-diol, its diacetic ester,
and its ditosylic esters, namely Co2(CO)6(µ-HOCH2-
CtCCH2OH) (7a ), Co2(CO)6(µ-AcOCH2CtCCH2OAc)
(8a ), and Co2(CO)6(µ-TsOCH2CtCCH2OTs) (9a ), was
undertaken (Scheme 7).
The diacetoxy complex 8a was isolated in 97% yield
by acetylation of the previously known diol complex
7a .31,37 Monocrystals of 8a were analyzed by X-ray
diffraction (Figure 5). The average C2 symmetry of the
solution structure revealed by NMR is preserved in the
crystal state. It is similar to that of 7a , which has been
only recently reported.31 The η2-CtC bond lengths in
both 7a and 8a lie in the classical range (1.344 and
1.333 Å, respectively) and are thus much longer than
in 3 (see preceding discussion). The C-C-CH2 angle is
141.2(4)° in 8a and 136.1° in 7a , the latter value
probably reflecting the occurrence of intramolecular
O-H‚‚‚H bonds.31 The Co‚‚‚CH2OAc distance is non-
bonding, whereas the propargylic C-OAc bonds (1.446
and 1.438 Å) do not exhibit any lengthening with respect
to standard values. No predissociation of the acetate
group is therefore structurally observed.
F igu r e 5. X-ray crystal structure of complex 8a . Selected
bond distances in Å: Co(1)-Co(2) ) 2.4684(9); Co(1)-C(2)
) 1.959(3); Co(1)-C(1) ) 1.947(4); Co(2)-C(2) ) 1.944(3);
Co(2)-C(1) ) 1.958(4); C(1)-C(2) ) 1.333(5); O(1)-C(3) )
1.438(4); O(2)-C(4) ) 1.446(5). Selected bond angles in
deg: C(2)-C(1)-C(3)
) 142.5(3); C(1)-C(2)-C(4) )
141.2(4); O(1)-C(3)-C(1) ) 107.4(3); O(2)-C(4)-C(2) )
107.8(3).
Surprisingly, although the mono(tosyloxy)butyne com-
plex 2a was not observed (vide supra), reaction of the
bis(tosyloxy)butyne 1b with Co2(CO)8 in ether produced
the heat-sensitive complex Co2(µ-TsOCH2CtCCH2OTs)-
(CO)6 (9a ) isolated in 88% yield. When a sample of 9a
was left in THF-d8 solution at room temperature over
several days, the propargylic CH2 13C and 1H NMR
signals disappeared, whereas the Co2+ complex
[Co(H2O)6][OTs]2 (identified by X-ray diffraction) was
recovered.38 This observation is consistent with an
intramolecular reduction of the ligand by a cobalt(0)
(37) (a) Greenfield, H.; Friedel, R. A.; Wotiz, J .; Markby, R.; Wender,
I. J . Am. Chem. Soc. 1954, 76, 1457-1458. (b) Pohl, D.; Ellermann,
J .; Knoch, F. A.; Moll, M. J . Organomet. Chem. 1995, 495, C6-C11.

878 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
Sch em e 8. P ossible Oxid a tion of Coba lt by Its
Dissocia ted 1,4-Bis(tosyloxy)bu t-2-yn e Liga n d a
occurring in the spectrometer and thereby generating
the cationic butatriene complex IId (Scheme 6).
Likewise, the diacetoxybutyne 12 was allowed to react
with [Ru3(µ-Cl)(CO)10]-, formed in situ from Ru3(CO)12
and [PPN][Cl]. The ruthenate complex [PPN][Ru3(µ-
Cl)(µ-AcOCH2CCCH2OAc)(CO)9] (13a ) was the sole car-
bonyl complex observed by IR. In contrast to the case
of the mono(tosyloxy) ligand 1a , the neutral acetate-
allenyl complex Ru3(µ-Cl)(µ-AcOCH2CCCH2)(CO)9 (13b)
was not spontaneously generated. Its formation required
protonation with HBF4 (Scheme 9). As in the case of
the alcohol complex 10b, the DCI/NH3 MS spectrum of
13b showed a parent ion multiplet at m/z 644, corre-
sponding to the butatriene complex IId generated in the
spectrometer via deacetoxylation of 13b (Scheme 6).
a
[Co] ) Co(CO)3.
Sch em e 9. Step w ise F or m a tion of a Neu tr a l
Allen yl Com p lex fr om Bu t-2-yn e-1,4-d iol a n d
1,4-Dia cetoxy-bu t-2-yn e (12)a
Thus, the acetate substituents of 12 are not displaced
by the [Ru3(µ-Cl)(CO)10]- anion. In contrast, the tosylate
substitutents of 1b were displaced by [Ru3(µ-Cl)CO)10]-
to afford [PPN][OTs] and a novel type of ruthenium
complex. The resulting IR spectrum exhibited an ab-
normal pattern, quite different from the one generally
observed for ruthenates of the type [PPN][Ru3(µ-Cl)-
(µ-RCCR)(CO)9]. Nevertheless, according to IR monitor-
ing, the reaction required 2 equiv of [PPN][Ru3(µ-Cl)-
(CO)10] for completion. Upon protonation, the newly
generated elusive species produced 5b in rather small
yield along with roughly equal amounts of Ru3(CO)12
(Scheme 10). In accordance with related reactions of 1,4-
bis(tosyloxy)but-2-yne (1b) with metalates [M]- (M )
FeCp(CO)2,42 WCp(CO)314), we propose that the initial
interaction between 1b and the cluster involves the
methylene groups rather than the triple bond: the
primary intermediate would thus correspond to the
structure [M]-CH2CtCCH2-[M] (15c),14,43 the bis-
propargylic version of the mono-propargylic intermedi-
ate 5c, proposed to result from the reaction of 1-(tosyl-
oxy)but-2-yne (1a ) with [Ru3(µ-Cl)(CO)10]- (Scheme 4).
In situ IR and NMR spectroscopy in THF-d8, however,
does not give evidence for the elusive species 15c.
Indeed, a detailed NMR analysis suggests that the
primary intermediate finally evolves to the butatriene-
type complex structure 15d . As indicated by the two sets
a
[Ru] ) Ru(CO)3.
atom and supports the picture Id of bis-propargylic
activation (Schemes6 and 8).
At 20 °C and 400 MHz, the H NMR signals of the
CH2OTs moieties of 9a in THF-d8 show a specific shift
with respect to the corresponding signals in DMF-d7
(∆δ H ) 0.44 ppm). A similar solvent effect is observed
for the corresponding 100 MHz C NMR signals (∆δ
1
1
13
13C
) -6.45 ppm).39 As previously established, NMR spec-
troscopy affords useful information on the dynamic
behavior of propargylium dicobalt hexacarbonyl com-
plexes.40 Here, the observed dependence of chemical
shifts on the solvent dielectric constant provides a hint
that 9a exists under the associated form (Ia ) in THF
(ꢀ ) 7.52) but undergoes a solvent-induced polarization
of the CH2-OTs bond toward dissociated forms (Ib, Id )
in DMF (ꢀ ) 38.25).41
(2) R u t h en iu m Ser ies. Reaction of the free but-
ynediol HOCH2CtCCH2OH with [PPN][Ru3(µ-Cl)(CO)10]
resulted in the formation of the expected anionic cluster
[PPN][Ru3(µ-Cl)(µ-HOCH2CCCH2OH)(CO)9] (10a ) (IR
monitoring). Protonation of 10a with HBF4 in THF
afforded the hydroxyallenyl complex 10b, analogous to
the allenyl derivative 4b (Scheme 9). The DCI/NH3 MS
spectrum of 10b clearly revealed a parent ion multiplet
at m/z 644, corresponding to a dehydroxylation of 10b
1
of 13C and H CH2 signals, and due to the stereogenicity
of the triruthenium clusters, the product is actually a
mixture of stereoisomers. In the 1H NMR spectrum, two
different propargylic CH2 groups occur as pairs of
doublets at high field (0.99, 1.94 for one isomer and 1.01,
1.93 ppm for the other) with a characteristic geminal
coupling constant (2J HH ) 2.4 Hz for both the isomers).
In the 13C spectrum the equivalent CH2 groups of the
two isomers occur at 43.74 and 43.82 ppm. 1H-13C
HMBC and HMQC correlations assigned the central
carbon atoms of the butatriene ligand at 128.83 and
131.17 ppm. Finally, a structure of the type 15d might
also be consistent with the observed behavior of the
complex as a masked form of the alkyl ruthenium 15b,
giving the allenyl complex 5b upon protonolysis of the
propargylic C-Ru bond with HBF4 (Scheme 10).
(38) Cabaleiro-Mart´ınez, S.; Castro, J .; Romero, J .; Garc´ıa-Va´zquez,
J . A.; Sousa, A. Acta Crystallogr., Sect. C 2000, C56, e249-e250.
(39) High fluxionality of the complex was also observed by VTP 1H
NMR in DMF-d7 between -50 and 20 °C.
(42) (a) Chiang, T.; Kerber, R. C.; Kimball, S. D.; Lauher, J . W. Inorg.
Chem. 1979, 18, 1687. (b) Rinze, P. V.; Mu¨ller, U. Chem. Ber. 1979,
112, 1973.
(43) This intermediate does not give the dissymmetrical structure
15b, and this is consistent with the report that the triple bond of
[M]-CH2CtCCH2-[M] complexes does not displace the acetonitrile
ligands of [Ru3(CO)10(MeCN)2].14
(40) Aime, S.; Milone, L.; Rossetti, R.; Stanghelli, P. L. Inorg. Chim.
Acta 1977, 22, 135-139.
(41) CRC Handbook of Chemistry and Physics, 78th ed.; Lide, D. R.
Ed.; CRC Press: Boca Raton, FL, 1997; p 6-139.

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 879
Sch em e 10. Rea ction of 1,4-Bis(tosyloxy)bu t-2-yn e (1b) w ith 2 Equ iv of in Situ F or m ed
a
[P P N][Ru 3(µ-Cl)(CO)10
]
a
[Ru] ) Ru(CO)3. It might be proposed that {Ru3} ) [Ru3Cl(CO)10].
Sch em e 11. F or m a tion of a Ca tion ic Bu ta tr ien e
Ru th en iu m Com p lexa
Con clu sion
The present work shows that the reactivity of func-
tionalized alkynes toward cobalt and ruthenium clusters
is dramatically affected by the nature of the leaving
group occupying one or two propargylic positions. When-
ever an OH or OAc substituent is present in propargylic
position(s), the initial interaction between the alkyne
and the cluster involves “normal” coordination of the
triple bond. Further elimination of the leaving group
and activation of a propargylic position then requires
the assistance of an acid. In contrast, an “abnormal”
behavior is observed in the presence of a very good
leaving group such as tosylate, particularly in the case
of 1,4-bis(tosyloxy)but-2-yne (1b), where putative Id and
elusive 15d butatriene-type complexes are suggested to
be produced in situ. A comparison of the orbitals and
Fukui indices for the elusive (DFT-otpimized) allenyl
cobalt complex [Co2(µ-η2-RCCCH2)(CO)6]+ (2b) and the
isolated allenyl ruthenium complex Ru3(µ-Cl)(µ-η3-CH3-
CCCH2)(CO)9 (5b) allows us to anticipate a parallel
electrophilic behavior for these two complexes. Finally,
the above experimental and theoretical results support
a structural analogy between cobalt and ruthenium
alkyne clusters, possibly exploitable in terms of reactiv-
ity. Significantly, the low Mulliken charge of the chlo-
ride ligand and the high-lying LUMO make the allenyl
ruthenium complex 5b globally less electrophilic than
the allenylium cobalt complex 2b. A Fukui index
analysis provides a rationale for the specific Nicholas
propargylic reactivity of allenylium cobalt complexes
with neutral nucleophiles: within the framework of the
HSAB theory, those have to be considered as hard, while
anionic nucleophiles have to be considered as soft and
should react at the cobalt carbonyl center. Such an
analysis indicates the same trend in the ruthenium
series. A hydride was indeed shown to react at the metal
center of the neutral complex 5b, as predicted for soft
nucleophiles. The reactivity of hard neutral nucleophiles
should be, however, restored by the cationic charge of
the butatriene complex [Ru3(µ-Cl)(µ-CH2CCCH2)(CO)9]+
(10d ). The latter is easily prepared in two steps from
the commercially available but-2-yne-1,4-diol. System-
atic studies of the nucleophilic C-functionalization of the
butatriene ligand of 10d will thus be the next challenge,
with the ultimate goal of synthesizing carbomeric car-
bocycles by alcynyl-propargyl coupling.51
a
[Ru] ) Ru(CO)3.
The above results were indicative that good leaving
groups such as tosylates are not exploitable in the
context of bis-propargylic activation. This led us to
devise an alternate strategy to generate the butatriene
complex IId , keeping in mind the observation of its
characteristic pattern in the mass spectrum of the
hydroxyallenyl complex 10b. Accordingly, 10b was
treated with 1 equiv of HBF4 in dichloromethane,
leading to a new cationic species which was crystallized
from the same solvent.44 The absence of a hydride signal
clearly indicated that protonation does not take place
at the metal core, whereas the IR spectrum exhibited
high-frequency CtO absorptions, consistent with the
occurrence of a cationic complex. The complex was
formulated as the cationic species [Ru3(µ-Cl)(µ-CH2-
CCCH2)(CO)9]+ (10d ) on the basis of NMR and mass
spectrometry. It was isolated in 54% yield (Scheme 11).
This complex is stable in CD3CN or (CD3)2CO solu-
tions at low temperature, allowing for its characteriza-
1
tion by 1H and 13C NMR. In the H NMR spectrum, two
doublets of doublets occur at 4.48 and 5.06 ppm. Their
large (2J HH ) 3.9 Hz) and small (5J HH ) 2.8 Hz) coupling
2
constants are consistent with two geminal Csp -H
protons of a butatriene ligand in a Cs environment
(owing to the Cs symmetry of the Ru3(µ-Cl)(CO)9 core,
a static C2 symmetry can be ruled out). The Cs sym-
metry is also supported by the observation of five IR
absorption bands, consistent with the 3 A′ + 2 A′′
stretching vibration analysis for this symmetry group.
The butatriene picture of the ligand is validated by the
1
coupling constant J CH ) 164 Hz, which is characteristic
2
for sp2 carbon atoms. Finally, the J HH and δ C () 43.00
ppm) values of the CH2 groups are almost identical with
those observed in situ for 15d (see above), giving further
support to the occurrence of a butatriene unit in the
latter.
13
Exp er im en ta l Section
THF and ether were distilled over Na/benzophenone. Pen-
tane and dichloromethane were distilled over P2O5. Ru3(CO)12
(44) A side product remained soluble in CH2Cl2, but its exact
structure could not be determined: see Experimental Section.

880 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
was prepared from RuCl3‚3H2O (J ohnson-Mattey) according
to a recently improved procedure.45 Co2(CO)8 was purchased
from Strem Chemicals. 2-Butyn-1-ol, 2-butyne-1,4-diol, tosyl
chloride, and acetic anhydride were purchased from Fluka.
Elemental analyses were performed at the Service de Mi-
croanalyse du LCC on a Perkin-Elmer 2400 apparatus. IR
spectra were recorded on a Perkin-Elmer GX FT-IR spectrom-
eter using a CaF2 cell. 1D-NMR spectra were recorded on
Bruker AC 200 and AM 250 spectrometers, at 200 and 250
(1a ; 0.60 g, 2.7 mmol) in Et2O (50 mL) at room temperature.
The reaction was monitored by IR spectroscopy: after 3 h of
stirring, the bridging carbonyl band at 1846 cm-1 disappeared,
and the solution was evaporated to dryness. The solid was
dissolved in pentane and filtered through Celite. The filtrate
1
was then evaporated, giving 3 as a red oil (0.736 g, 79%). H
NMR (CDCl3): δ 2.65 (s, 6 H, CH3Ct); 4.82 (s, 4 H, CH2O).
13C NMR (CDCl3): δ 20.26 (q, 1J CH ) 130.2 Hz, CH3Ct); 71.63
(t, 1J CH ) 144.7 Hz, CH2O); 92.35, 93.25, (2 s, η2-CtC); 199.67
(s, Co2(CO)6). MS (DCI/NH3): m/z 712 ([M + NH4]+). IR
(pentane): νCtO 2093 (m), 2057 (s), 2029 (s) cm-1. Recrystal-
lization from methanol afforded red crystals suitable for an
X-ray structure determination.
1
MHz, respectively, for H and at 50 and 63 MHz, respectively,
for 13C. 2D-NMR spectra were recorded on a Bruker AMX 400
apparatus. Positive chemical shifts at low field are expressed
in ppm by reference to TMS.
P r ep a r a tion of 1-(Tosyloxy)bu t-2-yn e (1a ).46 Tosyl chlo-
ride (2.94 g, 15.4 mmol) was added to a solution of but-2-yn-
1-ol (0.939 g, 13.4 mmol) in acetonitrile (5 mL). After it was
stirred for 10 min at room temperature, the mixture was cooled
to 0 °C and 10 M aqueous KOH solution (3 mL) was added.
After it was stirred overnight at room temperature, the
mixture was extracted in Et2O (3 × 30 mL). The organic phase
was dried over Na2SO4, filtered, and dried under vacuum. The
resulting solid 1a was recrystallized from methanol and
P r ep a r a tion of Com p lex 5b. Ru3(CO)12 (0.300 g, 0.47
mmol) and [PPN][Cl] (0.270 g, 0.47 mmol) were dissolved in
THF (30 mL). The solution was stirred for 3 h at room
temperature under N2 bubbling via a needle in the solution.
The formation of [PPN][Ru3(µ-Cl)(CO)10] was monitored by IR
(in THF, νCtO 2070 (w), 2026 (s), 1994 (vs), 1981 (s), 1952 (s),
1908 (w), 1801 (m), 1775 (w) cm-1). 1-(Tosyloxy)but-2-yne (1a ;
0.106 g, 0.47 mmol) was added. After a few minutes a white
solid ([PPN][OTs]) precipitated. The solution was filtered and
evaporated to dryness. The brown residue was then dissolved
in a few drops of dichloromethane and flash-chromatographed
over silica gel (1/1 pentane/CH2Cl2). After evaporation, complex
5b was obtained as a brown solid (0.208 g, 68%). 1H NMR (CD2-
Cl2): δ 3.07 (s, 3 H, CH3); 3.59 (d, 2J HH ) 3.2 Hz, 1 H, CHHRu);
1
recovered as white crystals (1.42 g, 47%). Mp: 49-50 °C. H
NMR (CDCl3): δ 1.71 (t, 3 H, CH3Ct); 2.43 (s, 3 H, CH3C6H4);
3
4.65 (s, 2 H, tCCH2O); 7.33 (d, 2 H, J HH ) 8.1 Hz, o-CH);
3
7.80 (d, 2 H, J HH ) 8.1 Hz, m-CH). 13C{1H} NMR (CDCl3): δ
3.60 (CH3Ct); 21.66 (CH3C6H4); 58.70 (tCCH2O); 71.00
(MeC≡); 86.18 (MeCtC); 128.13, 129.72 (o- and m- CH); 133.26
(ipso-CMe); 144.88 (ipso-CSO3). MS (DCI/NH3): m/z 259 ([M
+ NH4]+), 242 ([M + H]+). IR (Et2O): ν 942 (s), 1096 (w), 1178
(s), 1190 (m), 1369 (m), 1599 (w), 2924 (w) cm-1. Anal. Found
(calcd): C, 58.89 (58.92); H, 5.40 (5.58); S, 14.53 (14.27).
P r ep a r a tion of 1,4-Bis(tosyloxy)bu t-2-yn e (1b).46 The
above procedure was applied to the present synthesis, from
tosyl chloride (30.6 g, 160.3 mmol) and 2-butyne-1,4-diol (6.00
g, 69.7 mmol) as reagents. Recrystallization from methanol
afforded 1b as white crystals (11.52 g, 47%). 1H NMR (CDCl3):
δ 2.44 (s, 6 H, CH3C6H4); 4.56 (s, 4 H, tCCH2O); 7.33 (d, 4 H,
2
4.62 (d, J HH ) 3.2 Hz, 1 H, CHHRu). 13C NMR (CD2Cl2): δ
1
1
34.09 (t, J CH ) 165.0 Hz, CH2Ru); 37.29 (q, J CH ) 129.1 Hz,
CH3); 148.70 (s, RuCCH2Ru); 186.00, 189.08, 190.76, 191.99,
194.83, 196.18, 196.88 (br), 197.44, 199.47 (9 s, Ru3(CtO)9);
213.06 (pseudo q, 2J CH ) 5.1 Hz, MeCRu). MS (DCI/NH3): m/z
646 ([M + H]+). IR (THF): νCtO 2099 (m), 2076 (s), 2061 (w),
2047 (vs), 2038 (m), 2020 (m), 2015 (m), 1997 (m), 1983 (w).
Anal. Found (calcd): C, 24.27 (24.25); H, 0.71 (0.78); Cl, 5.42
(5.51). The solid was recrystallized from CH2Cl2/pentane to
afford yellow crystals suitable for an X-ray structure deter-
mination.
3
3J HH ) 8.4 Hz, o-CH); 7.55 (d, 4 H, J HH ) 8.4 Hz, m-CH). 13C
P r ep a r a tion of Com p lexes 6a a n d 6b. A 1 M solution of
K-Selectride in THF (0.155 mL, 0.155 mmol) was syringed into
a solution of the allenyl complex 5b (0.100 g, 0.155 mmol) in
THF (10 mL) at room temperature. The solution turned deep
red, while IR monitoring indicated that only half of the allenyl
complex had been consumed. Another 1 equiv of the K-
Selectride solution (0.155 mL, 0.155 mmol) was added, and
the final IR spectrum was fully consistent with the complex
[K][Ru3(µ-H)(CO)9(MeCCMe)] (6a ). The solution was evapo-
rated to dryness, and the residue was dissolved in CH2Cl2 (10
mL). The solvent was then cooled to -78 °C, and HBF4‚OEt2
(0.021 mL, 0.154 mmol) was syringed in. The latter was
concentrated and then chromatographed over silica gel (1/1
pentane/dichloromethane). After evaporation, complex 6b was
obtained as a brown solid (0.045 g, 47%). IR (CH2Cl2): νCtO
2017 (m), 1987 (vs), 1968 (broad s), 1944 (broad m) cm-1. MS
(DCI/NH3): m/z 614 ([MH]+); 586 ([MH - CO]+). 1H NMR
(CDCl3): δ -20.87, -18.65, -17.80 (3 s, 2 H; Ru‚‚‚H‚‚‚Ru); 2.61
(s, 6H, C2(CH3)2). Unless some decomposition occurs in CDCl3,
the occurrence of three hydride signals could be interpreted
as a result of a slow interconversion between tautomeric
species 6b (two types of different hydrides) and 6b′ (one type
of equivalent hydrides):
1
NMR (CDCl3): δ 21.84 (q, J CH ) 127.3 Hz, CH3C6H4); 57.25
(t, 1J CH ) 155.4 Hz, tCCH2O); 81.08 (s, MeCt); 86.18 (MeCt
C); 128.24, 130.07 (2 d, 1J CH ) 165.0 Hz, o- and m-CH); 132.86
(s, ipso-CMe); 145.61 (s, ipso-CSO3). IR (CD2Cl2): ν 1095 (w),
1178 (s), 1191 (s), 1360 (w), 1372 (vs), 1445 (w), 1495 (w), 1598
(m) cm-1. Anal. Found (calcd): C, 54.43 (54.81); H, 4.40 (4.60).
P r ep a r a tion of 1,4-Dia cetoxybu t-2-yn e (12). Pyridine (5
mL, 62 mmol) was syringed into a solution of but-2-yne-1,4-
diol (1.291 g, 0.15 mmol) in acetic anhydride (15 mL, 159
mmol). After the mixture was stirred for 3 h at room temper-
ature, 1 M aqueous HCl (50 mL) was added. The mixture was
extracted in Et2O (2 × 20 mL). The organic phase was dried
over MgSO4, filtered, concentrated, and dried overnight under
vacuum. Pure diacetate 12 was obtained as a colorless oil
1
(1.140 g, 45%). H NMR (CDCl3): δ 2.02 (s, 6 H, CH3CO); 4.64
1
(s, 4 H, tCCH2OAc). 13C NMR (CDCl3): δ 20.70 (q, J CH
)
129.9 Hz, CH3CO); 52.09 (t, 1J CH ) 152.9 Hz, tCCH2O); 80.77
(s, CtC); 1170.11 (-CdO). IR (CDCl3): ν 1028 (s), 1158 (m),
1224 (vs), 1360 (w), 1379 (m), 1434 (w), 1449 (w), 1745 (vs),
2947 (w) cm-1. Anal. Found (calcd): C, 56.28 (56.47); H, 6.11
(5.92).
P r ep a r a tion of Com p lex 3. Dicobalt octacarbonyl (0.916
g, 2.7 mmol) was added to a solution of 1-(tosyloxy)but-2-yne
[H-Ruγ-Ruâ‚‚‚H‚‚‚RuR‚‚‚] a [Ruγ‚‚‚H‚‚‚Ruâ‚‚‚H‚‚‚RuR]
(45) (a) Lavigne, G.; Saccavini, C.; Chauvin, R. In Inorganic Experi-
ments, 2nd ed.; Woolins, D. J ., Ed.; VCH: Weinheim, Germany, in
press. (b) Faure, M.; Maurette, L.; Donnadieu, B.; Lavigne, G. Angew.
Chem., Int. Ed. Engl. 1999, 38, 518-522.
(46) Eglinton, G.; Whiting, C. J . Chem. Soc. 1950, 3650-3653. For
other uses of this substrate, see: Brouard, C.; Pornet, J .; Miginiac, L.
Synth. Commun. 1994, 24(21), 3047. Bertram, H. J .; J ansen, M.;
Peters, K.; Meier, A.; Winterfeldt, E. Liebigs Ann. Chem. 1986, 456.
De Meijere, A.; J aekel, F.; Simoa, A.; Borrmann, H.; Ko¨hler, J .; J ohnels,
D.; Scott, L. T. J . Am. Chem. Soc. 1991, 113, 3995.
6b
6b′
P r ep a r a tion of Com p lex 7a . But-2-yne-1,4-diol (1.00 g,
1.16 mmol) was dissolved in diethyl ether (60 mL) at 40 °C.
Co2(CO)8 (3.97 g, 1.16 mmol) was added, and the mixture was
stirred for 3 h. The solution was concentrated twice, and
pentane (50 mL) was added. The solution was cooled to 0 °C
for ca. 20 min and then filtered. The remaining brown solid

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 881
was redissolved in diethyl ether, and this solution was filtered
over a small pad of Celite. The filtrate was concentrated to
dryness, and 7a was obtained as a red microcristalline solid
(2.25 g, 6.05 mmol, 52%). Mp: 130-134 °C. IR (Et2O): νCtO
alumina was avoided due to a partial decomposition of the
complex on the column. Nevertheless, the residual PPN+ salt
could be removed by a second extraction in pentane (2 × 20
mL) and subsequent evaporation, which afforded complex 10b
associated with ca. 10% of pentane as indicated by the 1H NMR
spectrum (Supporting Information) (yield 0.042 g, 20%). IR
(THF): νCtO 2099 (w), 2074 (s), 2044 (vs), 2005 (s), 1982 (sh,
1
2093 (m), 2053 (s), 2029 (s) cm-1. H NMR (CDCl3): δ 2.61 (s,
2 H, OH); 4.86 (s, 4 H, CH2).
P r ep a r a tion of Com p lex 8a . Butynediol complex 7a (0.80
g, 2.15 mmol) was dissolved in Ac2O (5 mL) at room temper-
ature. Pyridine was added (0.870 mL, 10.75 mmol) and the
solution was stirred for 12 h. One molar aqueous HCl (20 mL)
was added, and the mixture was extracted in Et2O. The organic
phase was washed with 5% aqueous NaHCO3 and dried over
MgSO4. Complex 8a was obtained as a microcrystalline solid
(0.949 g, 97%). MS (DCI/NH3): m/z 474 ([M + NH4]+); 397 ([M
- CH3CO2• + H]+), 369 ([M - CH3CO2• - CO + H]+), 341 ([M
1
w), 1964 (sh, w), 1589 (vw) cm-1. H NMR (CDCl3): δ 2.28 (t,
2
3J HH ) 5.2 Hz, 2H; OH); 3.61 and 4.63 (2 d, J HH ) 3.3 Hz,
3
2
CH2Ru); 4.90 and 5.09 (2 dd, J HH ) 5.2 Hz, J HH ) 13.6 Hz;
CH2O). 13C{1H} NMR (CDCl3): δ 35.19 (CH2Ru); 73.90 (CH2O);
152.46 (RuCCH2Ru); 185.50, 188.61, 191.42, 193.29, 195.36,
196.23 (br), 196.75, 198.99 (8 s, Ru3(CtO)9); 209.42 (OCH2CRu).
MS (DCI/NH3): m/z 679 ([M + NH4]+); 661 ([M + NH4
-
H2O]+); 644 ([MH - H2O]+). Anal. Found (calcd) for 10b‚0.1-
(pentane): C, 24.60 (24.38); H, 0.71 (0.96).
•
- CH3CO2 - 2 CO + H]+). IR (CDCl3): νCtO 2099 (m), 2061
1
(s), 2036 (s), 1740 (m) cm-1. H NMR (CDCl3): δ 2.10 (s, 6 H,
P r ep a r a tion of Com p lexes 13a a n d 13b. Ru3(CO)12
(0.300 g, 0.47 mmol) and [PPN][Cl] (0.270 g, 0.47 mmol) were
dissolved in THF (30 mL). The solution was stirred for 3 h at
room temperature under an N2 stream. The formation of [PPN]-
[Ru3(µ-Cl)(CO)10] was monitored by IR. A solution of 1,4-
diacetoxybut-2-yne (0.080 g, 0.47 mmol) in THF (10 mL) was
CH3); 5.24 (s, 4 H, CH2). 13C{1H} NMR (CDCl3): δ 20.28 (s,
CH3); 64.12 (s, CH2O), 89.20 (s, CtC), 170.40 (s, MeCdO),
198.44 (s broad, Co2(CO)6).
The solid could be recrystallized from methanol (0.621 g,
63%) to afford single crystals suitable for an X-ray structure
determination. Anal. Found (calcd): C, 37.11 (36.97); H, 2.10
(2.21); Co, 24.31 (25.84).
added. After
a few minutes the solution turned brown.
Complex 13a was characterized by IR. IR (THF): νCtO 2061
(w), 2036 (s), 1992 (vs), 1981 (s), 1962 (m), 1952 (m), 1924 (w),
P r ep a r a tion of Com p lex 9a . Co2(CO)8 (0.87 g, 2.5 mmol)
was added to a suspension of 1,4-bis(tosyloxy)but-2-yne (1b;
1.00 g, 2.5 mmol) in Et2O (50 mL). The dark brown color of
the solution faded off, while a red solid precipitated over 3 h
of stirring at room temperature. The solution was concentrated
twice and then filtered. Complex 9a was obtained as a brown
1835 (vw), 1736 (m), 1589 (vw) cm-1
.
The solution was then cooled to -20 °C, and HBF4‚OEt2
(0.064 mL, 0.47 mmol) was added dropwise. The solution was
filtered and then evaporated to dryness under vacuum. The
crude material (0.478 g) was obtained and then extracted with
diethyl ether (2 × 20 mL). Evaporation of the solvent yielded
complex 13b (0.215 g, 65% crude yield). Residual PPN+ salt
was removed by a second extraction with pentane (2 × 20 mL)
followed by evaporation, affording pure complex 13b (0.076 g,
1
solid (1.50 g, 2.2 mmol, 88%). H NMR (THF-d8): δ 2.46 (s, 6
3
H, CH3); 5.23 (s, 4 H, CH2); 7.45 and 7.85 (2 d, J HH ) 8.0 Hz,
aromatic CH). 13C{1H} NMR (THF-d8): δ 20.09 (CH3), 70.71
(CH2), 88.32 (η2-CtC), 128.19 and 130.18 (o and m aromatic
CH), 134.07 (aromatic CSO3), 145.34 (aromatic CMe), 198.57
(broad, Co2(CO)8). 1H NMR (400 MHz, DMF-d7, 293 K): δ 2.41
(s, 6 H, CH3); 5.67 (s, 4 H, CH2); 7.30 and 7.56 (2 d, 3J HH ) 8.0
Hz, aromatic CH). High fluxionality of the complex was
1
2
23%). H NMR (CDCl3): δ 3.59, 4.51 (2 d, J HH ) 3.3 Hz, 2 H,
CH2Ru); 5.05 and 5.53 (2 d, 2J HH ) 13.6 Hz, CH2OAc). 13C NMR
(CDCl3): δ 20.84 (q, 1J CH ) 129.8 Hz, CH3CO); 38.74 (t, 1J CH
)
165.6 Hz, CH2Ru); 74.73 (t, 1J CH ) 149.6 Hz, CH2OAc); 144.60
1
2
2
observed by VTP H NMR in DMF-d7 between -50 and 20 °C.
(pseudo t, J CH ) 3.9 Hz, RuCCH2Ru); 170.64 (pseudo q, J CH
) 6.8 Hz, MeCdO); 185.39, 186.36, 190.37, 191.79, 194.58,
195.31, 196.14 (br), 196.30 (8 s, Ru3(CtO)9); 210.53 (pseudo t,
AcOCH2CRu). MS (DCI/NH3): m/z 721 (([MNH4]+); 644 ([MH+
- AcOH]+). IR (THF): νCtO 2102 (w), 2077 (s), 2047 (vs), 2009
13C{1H} NMR (100 MHz, DMF-d7, 293 K): δ 20.78 (CH3), 64.26
(CH2), 90.87 (s, η2-CtC), 127.70 and 129.42 (o and m aromatic
CH and aromatic CMe), 139.55 (aromatic CSO3), 200.00 (broad,
Co2(CO)6). (-)-ESMS: m/z 171 (TsO-) (no signal from (+)-
ESMS or DCI/NH3). IR (THF): νCtO 2102 (vs), 2064 (vs), 2039
(s), 1998 (s), 1971 (sh, m), 1747 (br, m), 1589 (vw) cm-1
.
(vs); νS(dO) 1364 (s); 1189 (s), 1179 (s) cm-1. IR (KBr): νCtO
Alter n a tive Rou te to 5b fr om [Ru 3(CO)12], [P P N][Cl],
a n d 1,4-Bis(tosyloxy)bu t-2-yn e. 1,4-Bis(tosyloxy)but-2-yne
(1b; 0.093 g, 0.236 mmol) was added to a solution of [PPN]-
[Ru3(µ-Cl)(CO)10], prepared in situ from Ru3(CO)12 (0.300 g,
0.47 mmol) and [PPN][Cl] (0.270 g, 0.47 mmol) in THF (30
mL) (see above). After a few minutes, the solution turned
brown, at which point the formation of the intermediate 15d
was checked by IR. After evaporation of the solvent, the crude
product was analyzed by NMR in THF-d8. IR (THF): νCtO 2124
(vw), 2058 (m), 2027 (vs), 2008 (s), 1974 (m), 1908 (vw), 1829
(w), 1589 (vw) cm-1. 1H NMR (400 MHz, THF-d8): δ 0.99 (2J CH
) 2.4 Hz; CH isomer 1); 1.01 (2J CH ) 2.4 Hz; CH isomer 2);
1.93 (2J CH ) 2.4 Hz; CH isomer 1); 1.94 (2J CH ) 2.4 Hz; CH;
isomer 2). 13C{1H} NMR (100 MHz, THF-d8): δ 43.74 (CH2,
isomer 1); 43.82 (CH2, isomer 2); 128.83 (dCd, isomer 1);
131.17 (dCd, isomer 2); 193.34, 196.42, 197.15, 197.86, 198.46,
198.69, 200.93, 204.42, 216.43, 228.21 (9 s over a broad signal;
RuCO). The above signal assignments were based on consis-
tent cross-peaks in 1H-13C HMBC anf HMQC spectra (see
main text). Signals of THF, PPN+, and grease impurities were
omitted.
2
2103 (w), 2117 (vs), 2063 (vs), 2031 (vs); νS(dO)2 1348 (w); 1188
(m), 1171 (m) cm-1. UV-vis: λabs 276 (ꢀmax); 310 (sh); 352 nm
(ꢀ/ꢀmax ) 0.41).
Several attempts to obtain elemental analyses gave erratic
results: this is likely due to the poor stability of the complex,
1
the purity of which is however supported by H and 13C{1H}
NMR spectra (Supporting Information).
P r ep a r a tion of Com p lexes 10a a n d 10b. Ru3(CO)12
(0.200 g, 0.313 mmol) and [PPN][Cl] (0.180 g, 0.314 mmol)
were dissolved in THF (20 mL). The solution was stirred for 3
h at room temperature under N2 bubbling via a needle in the
solution. The formation of [PPN][Ru3(µ-Cl)(CO)10] was moni-
tored by IR. 1,4-Dihydroxybut-2-yne (0.027 g, 0.314 mmol) was
added, and after a few minutes the solution turned deep
brown. Complex 10a was obtained after evaporation of the
solvent (0.402 g, quantitative). IR (THF): νCtO 2071 (w), 2059
(w), 2033 (s), 1989 (vs), 1978 (s), 1958 (m), 1947 (m), 1919 (w),
1835 (vw), 1681 (vw), 1589 (vw).
The solution was then cooled to -20 °C, and HBF4‚OEt2
(0.043 mL, 0.316 mmol) was syringed in. The reaction medium
was filtered and the solvent was removed under vacuum,
leaving a crude material (0.282 g) which was extracted with
diethyl ether (20 mL). Evaporation of the solvent yielded
complex 10b (0.148 g, 70% crude yield). Although the unfunc-
tional allenyl complex 5b could be purified further by chro-
matography, chromatography of crude 10b over silica gel or
Alternatively, the THF solution was cooled to -78 °C,
protonated with HBF4 (0.032 mL, 0.235 mmol), and then
evaporated to dryness at room temperature. The residue was
dissolved in a few drops of dichloromethane and chromato-
graphed over silica gel using pentane as eluent. The colored
fraction contained a mixture of the allenyl complex 5b and

882 Organometallics, Vol. 21, No. 5, 2002
Soleilhavoup et al.
Ru3(CO)12. After evaporation of pentane, the residue was
treated with acetone, from which Ru3(CO)12 precipitated (0.028
g, 9%). Evaporation of the acetone filtrate afforded the allenyl
complex 5b (0.024 g, 8%).
Parr21a and defined as the partial derivative of the electronic
density F(r ) with respect to the total number of electrons N at
constant external potential v(r ). A Maxwell relation links the
chemical potential µ and f(r) as50
P r ep a r a tion of Com p lex 10d . Ru3(CO)12 (0.600 g, 0.94
mmol) and [PPN][Cl] (0.540 g, 0.94 mmol) were dissolved in
THF (60 mL). The solution was stirred for 3 h at room
temperature under CO bubbling via a needle in the solution,
until the characteristic red color of the [PPN][Ru3(µ-Cl)(CO)10]
salt was obtained. After addition of 1,4-dihydroxybut-2-yne
(0.081 g, 0.94 mmol), the formation of [PPN][Ru3(µ-Cl)(CO)9-
(µ-HOCH2CCCH2OH)] was monitored by infrared spectros-
copy. The solution was then cooled to -78 °C, and 2 equiv. of
HBF4‚OEt2 was syringed successively (2 × 0.128 mL, 2 × 0.94
mmol). The reaction medium was then concentrated to dryness
at room temperature. Dichloromethane (30 mL) was added,
and the resulting suspension was filtered. Complex 10d was
obtained as a pale yellow solid (0.369 g; 54%). IR (THF): νCtO
f(r )) (∂F/∂N)v ) (∂µ/∂v(r ))N
Reactivity indices to describe molecular reactivity have
therefore been proposed to describe (i) the nucleophilic attack
on the system
f+(r ) ) (∂F/∂N)+
v
(ii) the electrophilic attack on the system
f-(r ) ) (∂F/∂N)-
v
and (iii) the radical attack on the system
2140 (w), 2114 (w), 2070 (sh), 2059 (vs), 2003 (s, broad) cm-1
.
FAB MS: m/z 644 (M+); 616 ([M - CO]+); 588 ([M - 2CO]+);
f0(r ) ) 1/2(f+(r ) + f-(r ))
1
560 ([M - 3 CO]+). H NMR (200 MHz, CD3CN; T ) 293 K):
2
5
δ 4.48 and 5.06 (2 dd, 4H, J HH ) 3.9 Hz, J HH ) 2.8 Hz;
diastereotopic H2CdCdCdCH2). 1H NMR (300 MHz, CD3CN;
T ) 238 K): δ 4.49 and 5.06 (2 dd, 4H, J HH ) 3.8 Hz, J HH
Because the evaluation of these derivatives is quite com-
plicated, a finite difference scheme has been proposed to
evaluate f(r )
2
5
)
3.0 Hz; 13C satellites; 1J CH ) 164 Hz; diastereotopic H2CdCd
CdCH2). 13C{1H} NMR (75 MHz, CD3CN, T ) 238 K): δ 43.00
(CH2); 184.60 (medium; (Ru(CO)2); 188.00 (medium; (Ru(CO)2),
188.2 (intense; central Ru(CO)3), 191.60 (medium; (RuCO)2).
The equivalence of the central Ru(CO)3 carbonyl ligands is
tentatively and preliminarily assigned from the relative in-
tensities of the carbonyl 13CO signals. The signal of the
butatriene central carbon atoms was not detected. 19F NMR
(188 MHz, CD3CN): δ -69.49, -70.30, -70.35 (BF4-). Two
attempts to obtain elemental analysis gave erratic results: this
is likely due to the poor stability of the complex, the purity of
which is however supported by 1H, 13C{1H} and J -mod-13C
NMR spectra (Supporting Information).
f+(r ) ) FN+1(r ) - FN(r )
f-(r ) ) FN(r ) - FN-1(r )
f0(r ) ) 1/2(FN+1(r ) - FN-1(r ))
involving the electronic density of the systems with N + 1, N,
and N - 1 electrons, respectively.
A further approximation allows us to design the condensed
Fukui functions f(k), which are atomic reactivity indices in
contrast to the previous local Fukui functions:
Evaporation of the CH2Cl2 filtrate afforded a solid residue
(0.728 g), containing [PPN]+ cations, and a side product, the
structure of which could not determined. As complementary
details, some of its spectroscopic data are given hereafter. IR
(CH2Cl2): νCtO 2086 (m), 2080 (m), 2055 (s, sharp), 2017 (s)
f+(k)) -QN+1(k) + QN(k)
f-(k)) -QN(k) + QN-1(k)
f0(k)) 1/2(-QN+1(k) + QN-1(k))
1
cm-1. H NMR (200 MHz, CDCl3): δ 4.58 (dt, J HH ) 13.8 Hz,
J HH ) 2.0 Hz, 1 H); 4.70 (d, J HH ) 13.8 Hz; 1 H); 4.77 (d, J HH
1
) 2.0 Hz, 2 H). 13C NMR (62 MHz, CDCl3): δ 68.55 (t, J CH
)
The gross charge Qk was calculated from
population analysis.
a Mulliken
1
150 Hz); 81.00 (t, J CH ) 153 Hz); 117.5 (s).
The global hardness η ) 1/S (S ) softness) has been
1
evaluated using the finite-difference approximation (the
/
2
Com p u ta tion a l Meth od s
factor is now omitted in recent publications):22
Full geometry optimization and vibrational analysis of the
allenylium cobalt complex 2b was performed at the B3PW91/
6-31G* level using Gaussian98.47 Single-point energy calcula-
tions were performed on the optimized structure 2b at the
B3PW91/6-31G*/DZVP(Co) level and on the X-ray crystal
structure of 5b at the B3PW91/6-31G*/DZVP(Ru) level using
Gaussian98.48 Visualization of frontier orbitals was performed
using Molekel.49
η ) 1/S ) I - A
It has been calculated from energy differences involving the
system under consideration (N electrons) and the correspond-
ing reduced and oxidized species obtained by vertical ionization
(i.e. with the same geometry):
η ) 1/S ) EN+1 + EN-1 - 2EN
The frontier orbitals are involved in a quantity called the
Fukui function f(r ), first introduced in the 1980s by Yang and
(48) Godbout, N.; Salahub, D. R.; Andzelm, J .; Wimmer, E. Can. J .
Chem. 1992, 70, 560. Basis sets were obtained from the Extensible
Computational Chemistry Environment Basis Set Database, as de-
veloped and distributed by the Molecular Science Computing Facility,
Environmental and Molecular Sciences Laboratory, which is part of
the Pacific Northwest Laboratory, P.O. Box 999, Richland, WA 99352,
and funded by the U.S. Department of Energy. The Pacific Northwest
Laboratory is a multi-program laboratory operated by Battelle Memo-
rial Institute for the U.S. Department of Energy under Contract DE-
AC06-76RLO 1830. Contact David Feller or Karen Schuchardt for
further information.
(47) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B. G.; Chen,
W.; Wong, M. W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.;
Pople, J . A. Gaussian 98, revision A.7; Gaussian, Inc.: Pittsburgh, PA,
1998.
(49) Flu¨kiger, P. F.; Portman, S. Molekel 3.04; University of Geneva
and CSCS/SCSC-ETHZ, Switzerland, 1999.
(50) Parr, R. G.; Yang, W. Density-Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989.

Propargylic Activation via Co and Ru Complexes
Organometallics, Vol. 21, No. 5, 2002 883
Ack n ow led gm en t. We are indebted to Prof. Michael
McGlinchey for stimulating discussions and useful
suggestions, to Ce´cile Destombes, Antonetta Mohanu,
and Tal Perry for experimental assistance, to Dr.
Yannick Coppel for recording 2D-NMR spectra, and to
Philippe Arnaud for computational assistance. We also
wish to thank the Ministe`re de l’Education Nationale
de la Recherche et de la Technologie for financial
support, and CALMIP (CALcul intensif en MIdi-
Pyre´ne´es, Toulouse, France) for computational facilities.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data for compounds 3, 5b, and 8a , including tables of crystal
data, atomic coordinates, bond lengths and angles, and aniso-
1
tropic thermal parameters and figures giving H and 13C{1H}
NMR spectra of complex 9a , the 1H NMR spectrum of complex
1
10b and H, 13C{1H}, and J -Mod-13C NMR spectra of complex
10d . This material is available free of charge via the Internet
at http://pubs.acs.org.
(51) Maurette, L.; Godard, C.; Frau, S.; Lepetit, C.; Soleilhavoup,
M.; Chauvin, R. Chem. Eur. J . 2001, 7, 1165.
OM010568W