Oxidative dehydrodimerization of rhenium vinylidene complex (η5-C5H5)(CO)2ReCC(H)Ph: Two competitive routes of coupling of σ-phenylethynyl intermediate [(η5-C5H5)(CO)2ReCCPh] .. X-ray structures of rhenium mononuclear (η5-C5H5)(CO)2ReCC(H)Ph

Article abstract of DOI:10.1016/j.jorganchem.2004.07.038

The oxidation of the rhenium vinylidene complex (η⁵-C ₅H₅)(CO)₂ReCC(H)Ph (2) with one equivalent of AgBF₄ or (C₅H₅)₂FeBF₄ leads to the radical cation [(η⁵-C₅H ₅)(CO)₂ReCC(H)Ph]⁺ (2⁺) which undergoes dehydrodimerization only in the presence of triethylamine affording a mixture of the binuclear compounds (η⁵-C₅H ₅)(CO)₂ReCC(Ph)C(Ph)CRe(CO)₂(η⁵- C₅H₅) (6, 55%) and [(η⁵-C₅H ₅)(CO)₂Re]₂(μ₂-CC(Ph)CCPh) (9, 22%). Both 6 and 9 are believed to arise via competitive C_β- C_β and C_β-Re couplings of the intermediate σ-phenylethynyl radicals [(η⁵-C₅H ₅)(CO)₂ReCCPh]^. (5^.). The former process directly yields 6and the latter one produces 9 after reductive elimination and a 1,2-shift of the metal containing moiety. The enthalpies of C_β-C_β (-30.3 kcal/mol) and C_β-Re (+0.3 kcal/mol) coupling processes estimated by DFT calculations are in accordance with the 6:9 ratio observed. The electrochemical behavior of 2, 6, 9 was studied by cyclic voltammetry. The X-ray structures of 2 and 9 are reported.

Full text of DOI:10.1016/j.jorganchem.2004.07.038

Journal of Organometallic Chemistry 689 (2004) 3837–3846
www.elsevier.com/locate/jorganchem
Oxidative dehydrodimerization of rhenium vinylidene complex
(g5-C5H5)(CO)2Re@C@C(H)Ph: two competitive routes of
coupling of r-phenylethynyl intermediate
[(g5-C5H5)(CO)2ReACBCPh]Å. X-ray structures of rhenium
mononuclear (g5-C5H5)(CO)2Re@C@C(H)Ph and binuclear
[(g5-C5H5)(CO)2Re]2(l2-C@C(Ph)CBCPh) vinylidene compounds
Dmitry A. Valyaev, Oleg V. Semeikin, Mikhail G. Peterleitner, Yuri A. Borisov,
Viktor N. Khrustalev, Andrei M. Mazhuga, Evgeny V. Kremer, Nikolai A. Ustynyuk
*
A.N. Nesmeyanov Institute of Organoelement Compounds (INEOS) Russian Academy of Sciences, Vavilov Street 28, Moscow 119991, Russia
Received 22 July 2004; accepted 22 July 2004
Available online 24 August 2004
Abstract
The oxidation of the rhenium vinylidene complex (g5-C5H5)(CO)2Re@C@C(H)Ph (2) with one equivalent of AgBF4 or
(C5H5)2FeBF4 leads to the radical cation [(g5-C5H5)(CO)2Re@C@C(H)Ph]+Å (2+Å) which undergoes dehydrodimerization only in
the presence of triethylamine affording a mixture of the binuclear compounds (g5-C5H5)(CO)2Re@C@C(Ph)C(Ph)@C@Re
(CO)2(g5-C5H5) (6, 55%) and [(g5-C5H5)(CO)2Re]2(l2-C@C(Ph)CBCPh) (9, 22%). Both 6 and 9 are believed to arise via competitive
Cb–Cb and Cb–Re couplings of the intermediate r-phenylethynyl radicals [(g5-C5H5)(CO)2ReACBCPh]Å (5Å). The former process
directly yields 6 and the latter one produces 9 after reductive elimination and a 1,2-shift of the metal containing moiety. The enthal-
pies of Cb–Cb (ꢀ30.3 kcal/mol) and Cb–Re (+0.3 kcal/mol) coupling processes estimated by DFT calculations are in accordance with
the 6:9 ratio observed. The electrochemical behavior of 2, 6, 9 was studied by cyclic voltammetry. The X-ray structures of 2 and 9 are
reported.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Oxidative dehydrodimerization; Rhenium vinylidene complex; Cyclic voltammetry; DFT calculations; X-ray analysis
1. Introduction
rials [3]. Such compounds are also promising as reagents
for organic syntheses [4]. The main attention was paid to
l-1,3-butadiyne-1,4-diyl [M]ACBCACBCA[M] and in
the considerably lesser extent to l-1,3-butadiene-1,4-diyl
[M]ACH@CHACH@CHA[M] and other compounds.
One of the most effective and frequently used meth-
ods for the synthesis of such binuclear compounds is a
redox activated process of dimerization or dehydro-
dimerization of r- and r,p-complexes of transition met-
als [4a–4d,5]. In particular, it was shown that oxidative
dehydrodimerization of mononuclear vinylidene
Binuclear complexes with the transition metal atoms
linked by a conjugated chain of sp- and/or sp2-carbon
atoms has attracted the attention of researchers prima-
rily as models for electron conductivity phenomena at
a molecular level [1], as well as generating compounds
with uses in nonlinear optics [2] and liquid crystal mate-
*
Corresponding author. Tel.: +7 95 135 5064; fax: +7 95 135 5085.
E-mail address: ustynyuk@ineos.ac.ru (N.A. Ustynyuk).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.07.038

3838
D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
complexes [M]@C@C(H)R (I) to l2-g1:g1-2,3-R2-1,3-
butadiene-1,4-diylidene (l-divinylidene) compounds
[M]@ C@C(R)AC(R)@C@[M] (II) can proceed by three
possible routes (Scheme 1) differing by the type of trans-
formation of the primary oxidation product – 17-e rad-
ical cation I+Å.
(1) I+Å undergoes homolytic rupture of the Cb–H
bond leading to the 16-e r-ethynyl cation [M]+ACB
CR (III+) (step (b)). The following dimerization of III+
to 2-butene-1,4-diylidyne dication [M]+BCAC(R)@
C(R)ACB[M]+ (IV2+) and two-electron reduction (steps
(c) and (d), respectively) result in the product II. Isolated
instances of processes (b), (c) and (d) [5d–5f] are known.
According to the route (a) + (b) + (c) + (d) the electro-
chemical or chemical dehydrodimerization of manga-
nese vinylidene complex ([M]–Mn(CO)2(g5-C5H5),
R = Ph) can be performed without base [5f].
of (g5-C5H5)(CO)2Mn@C@C(H)Ph occurs in the pres-
ence of triethylamine [5f].
Earlierwehavestudiedtheoxidativedehydrodimeriza-
tion of the manganese phenylvinylidene complexes (g5-
C5R5)(CO)(L)Mn@C@C(H)Ph (R = H, Me; L = CO,
PPh3) [5f,5g]. In this work we developed the new method
for the synthesis of the p-phenylacetylene (g5-C5H5)
(CO)2Re(g2-PhCBCH) (1) and phenylvinylidene (g5-
C5H5)(CO)2Re@C@C(H)Ph (2) complexes of rhenium
and studied the oxidative dehydrodimerization of 2.
2. Results and discussion
2.1. The synthesis of the vinylidene complex 2 and the
study of its oxidative dehydrodimerization
(2) I+Å undergoes direct Cb–Cb coupling to the
18-e l-g1:g1-2,3–R2–butane–1,4–diylidyne intermediate
[M]+BCACH(R)ACH(R)ACB[M]+ (V2+); two-electron
reduction of V2+ leads to the corresponding 19-e, 19-e
diradicals [M]ÅBCACH(R)ACH(R)ACB[M]Å (VÅÅ) and
finally to the formation of II via homolytic scission of
Cb–H bond ((a) + (e) + (f) + (g)). According to this
route the oxidative dehydrodimerization of the manga-
nese complexes ([M] = Mn(CO)2(g5-C5Me5) and
Mn(CO)(PPh3)(g5-C5H5), R = Ph), occurs [5g].
(3) The presence of base makes possible the dehydro-
dimerization through deprotonation of I+Å to the radical
{[M]ACBCR}Å (IIIÅ) followed by Cb–Cb dimerization of
the latter (steps (h) and (i), respectively). It is this route
according to which the oxidative dehydrodimerization
The chemistry of 2 is much less explored in compar-
ison to its manganese analogue (g5-C5H5)
(CO)2Mn@C@C(H)Ph probably because of its low
accessibility. The complex 2 was synthesized earlier by
photochemical reaction of (g5-C5H5)Re(CO)3 with phe-
nylacetylene in THF at 5 ꢁC with the overall yield 12%.
The binuclear complexes 3 ((l-g1:g2-2,3-diphenyl-1,
3-butadien-1-ylidene)-bis-(cyclopentadienyldicarbonyl-
rhenium), 4.3%) and 4 ((l2-phenylvinylidene)-bis-(cyclo-
pentadienyldicarbonylrhenium), 3%) were also isolated
[6a]. The small yield of 2 and a laborious chromato-
graphic separation encouraged us to develop a new
more effective procedure. UV-irradiation of a cyclopen-
tadienyltricarbonylrhenium solution in THF with the
immersed lamp at ꢀ50 ‚ ꢀ15 ꢁC resulted in the forma-
.
+
H
e
H
R
[M]
[M]
C
C
C
+
C
(a)
R
.
I
I
(b)
.
H+
(e)
H
(h)
H
+
R
+
[M]
C
C
[M]
C
C
+
R
+
.
[M]
C
C
[M]
C
C
R
R
III
++
H
V
.
III
(c)
(f)
+ 2 e
(i)
R
C
H
+
R
C
.
[M]
R
C
C
[M]
.
+ 2 e
C
C
[M]
2H
(g)
+
C
C
.
[M]
C
[M]
C
[M]
(d)
C
C
R
R
R
HV..
++
IV
II
Scheme 1.

D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
3839
tion of (g5-C5H5)(CO)2Re(THF), the conversion of the
initial compound being 80–90% as estimated by IR-
spectroscopy (Scheme 2). The reaction of this product
with phenylacetylene at room temperature led to the for-
mation of the p-phenylacetylene complex (g5-
C5H5)(CO)2Re(g2-PhCBCH) (1) as the main product.
Compounds 2–4 were also formed. Usually the reaction
sequence was carried out without isolation of pure 1; it
was fully characterized by spectral methods and its
structure is certain.
The acetylene–vinylidene rearrangement of 1 pro-
ceeds in refluxing THF and in contrast to the relative
manganese compounds [5g,6b] requires no basic cataly-
sis. The yield of 2 in this procedure is 30% based on the
initial (g5-C5H5)Re(CO)3. The molecular structure of 2
was determined by X-ray analysis (see Fig. 2 and the
text below).
The oxidative dehydrodimerization of 2 was studied
under conditions used previously for the manganese
analogue (g5-C5H5)(CO)2Mn@C@C(H)Ph [5f]. The oxi-
dation of 2 with one equivalent of AgBF4 Æ3dioxane in
dichloromethane led to the radical cation 2+Å. The
course of the process can be conveniently IR monitored
by the decrease of the intensity of 1992 (s), 1916 (s)
(mCO), 1620 (w), 1588 (w) (mC@C) bands of 2 and the in-
crease of the intensity of new 2088 (s), 2032 (s) (mCO
)
bands of 2+Å. According to the IR-spectroscopy data
the formation of 2+Å proceeds quantitatively within sev-
eral minutes at ꢀ20 ꢁC. The intermediate 2+Å persists in
solution at ꢀ5–0 ꢁC and during 1 h no new compounds
were detected; the reduction of this solution by the ex-
cess of cobaltocene regenerates the initial 2 with 79%
yield. The radical cation 2+Å gradually decomposes at
higher temperature. Under CV conditions 2 undergoes
an irreversible one electron oxidation at +0.36 V (vs.
Fc) (Fig. 1(a), peak A1), no reduction peaks of dimeriza-
tion products being detected by the reverse scanning of
potential. The compound 2 also has an irreversible one
electron reduction peak at ꢀ2.38 V (Fig. 1(a), peak
A2). Thus, in contrast to the relative manganese com-
Fig. 1. Cyclic voltammograms of complexes 2 (a), 6 (b), 9 (c) (CH2Cl2,
GC-electrode, 0.1 M Bu4NPF6, v = 200 mV, 2 · 10ꢀ3 M, relative to the
Cp2Fe/Cp2Fe+Å couple (+0.46 V, DE = 60 mV).
hv
PhCCH
72h 20
20h
60
Ph
Re
Re
OC
Re
C
THF 40
OC
OC
OC
CO
O
C
CO
OC
H
1
Ph
H
Re
OC
Re
OC
Ph
Ph
C
C
+
+
OC
OC
Re
CO
Re
Re
CO
H
CO
OC
CO
CO
Ph
CH2
2
30%
3
4
Scheme 2.

3840
D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
pounds the intermediate radical cation 2+Å does not react
through the routes (1) and (2) of Scheme 1 and does not
afford any dimerization products.
of the cation radical 6+Å on the electrode surface. The
voltammogram of the isomeric complex 9 shows two
one electron irreversible peaks C1 and C2 (Fig. 1(c)) at
+0.47 and +1.03 V, respectively.
We obtained the dehydrodimerization products only
by oxidation of 2 in the presence of base. The treatment
of 2 with [(g5-C5H5)2Fe]BF4/triethylamine couple in
dichloromethane at room temperature resulted in a mix-
ture of two isomeric binuclear complexes 6 (55%) and 9
(22%) (Scheme 3). Complexes 6 and 9 were separated by
column chromatography on silica and fully character-
ized. The structure of 9 was established by X-ray analy-
sis (see Fig. 3 and the text below).
Electrochemical properties of the binuclear com-
plexes were studied by CV. The l-divinylidene complex
6 undergoes an irreversible one electron oxidation at
+0.23 V (Fig. 1(b), peak B1) with no other oxidation
peaks being observed up to +1.5 V (vs. Fc). This fact
is in some discrepancy with the literature data for the
structurally similar manganese l-divinylidene complexes
(g5-C5R5)(CO)LMn@C@C(Ph)AC(Ph)@C@MnL(CO)
(g5-C5R5) (R = H, L = CO, PPh3; R = CH3, L = CO)
[4e,5f–5g] as well as with the data for silver tetrafluorob-
orate oxidation of 6 (6 in dichloromethane was oxidized
stepwise to the cation radical 6+Å and to the dication
62+). The absence of the second oxidation peak under
CV conditions can be explained by the specific behavior
The oxidative dehydrodimerization of 2 involves a
deprotonation of the radical cation 2+Å by triethylamine
(Scheme 3, step (a)) to the r-phenylethynyl radical 5Å –
the direct precursor of the dimeric products 6 and 9.
The structure of 5Å can be presented as a resonance hy-
brid of the metal- and carbon-centered radicals. The
Cb–Cb type dimerization (step (b)) results in the ex-
pected l-divinylidene product 6, whereas the C–Re type
one (step (c)) results in 9 after reductive elimination in 7
and a 1,2-shift of the metal moiety in 8 (steps (d) and (e),
respectively). The carbon-metal couplings for the 17-e
transition metal r-alkynyl complexes were not yet de-
scribed. The enthalpies of Cb–Cb (5Å ! 6, ꢀ30.3 kcal/
mol) and C–Re (5Å ! 7, +0.3 kcal/mol) dimerizations
were calculated by DFT method (RB3LYP/LanL2DZ)
with full optimization of the geometry. Thus the
predominant formation of 6 is caused by the thermody-
namic preference of carbon–carbon coupling over C–Re
coupling. At the same time according to the calculated
data the final product of C–Re dimerization 9 is more
stable than the Cb–Cb dimerization product 6 by
5.2 kcal/mol. Detailed DFT investigation of some even-
.
+
H+
.
Re
Re
OC
Re
Ph
C
Ph
C
(a)
C
OC
OC
OC
CPh
OC
.
OC
H
17 e
.
18 e
.
2+
17 e
5
(c)
(b)
Ph
Ph
Ph
Re
CO
C
C
C
Re
Re
Re
CO
OC
CO
CO
CPh
OC
C
CO
CO
6
7
(d)
Ph
Ph
CO
CO
Re
Re
CO
Ph
Re
(e)
C
Re
CO
OC
CO
CO
CO
Ph
9
8
Scheme 3.

D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
3841
Table 1
and odd-electron rhenium complexes relevant to this
study is in progress and the results will be published
separately.
˚
Selected bond distances (A) and angles (ꢁ) for complex 2
Re(1)–C(1)
Re(1)–C(2)
Re(1)–C(8)
1.892(14)
1.926(15)
1.912(14)
Re(1)–Cp
C(8)–C(9)
C(9)–C(10)
1.963(15)
1.296(18)
1.471(19)
We ascertained by a special experiment that 6 cannot
be converted into 9 by the treatment with Cp2FeBF4/
NEt3 couple (dichloromethane, room temperature).
Ferrocenium was partially converted (up to 40–45%)
into ferrocene but no products of the l-divinylidene 6
transformation were found and it was recovered almost
quantitatively. We believe that the primary oxidation
products 6+Å and 62+ were reduced to 6 by triethylamine
as was found earlier for the manganese analogues of 6+Å
and 62+, i.e. [(g5-C5H5)(CO)2Mn@C@C(Ph)AC(Ph)@
C@Mn(CO)2(g5-C5H5)]n+ (n = 1, 2) [5f].
Attention should be paid to the difference in the
course of the oxidative dehydrodimerizations of 2 and
its manganese analogue (g5-C5H5)(CO)2Mn@C@
C(H)Ph in the presence of triethylamine. In the case of
the manganese complex the Cb–Cb dimerization product
(g5-C5H5)(CO)2Mn@C@C(Ph)AC(Ph)@C@Mn(CO)2
(g5-C5H5) is exclusively formed under these conditions
[5f]. It is obvious that the C–Mn dimerization product
(g5-C5H5)(CO)2Mn@C@C(Ph)AMn(CBCPh)(CO)2(g5-
C5H5) is thermodynamically unfavourable, because the
formation of cyclopentadienyl complexes of manganese
with a four leg piano stool geometry is sterically prohib-
ited. This assumption was confirmed by DFT
calculations data, according to which the formation
enthalpy of the C–Mn dimer from [(g5-C5H5)(CO)2-
MnACBCPh]Å is +70.7 kcal/mol.
C(1)–Re(1)–C(2)
C(1)–Re(1)–C(8)
C(2)–Re(1)–C(8)
C(1)–Re(1)–Cp
83.6(5)
92.5(5)
91.8(6)
125.7(6)
C(2)–Re(1)–Cp
C(8)–Re(1)–Cp
C(9)–C(8)–Re(1)
C(8)–C(9)–C(10)
125.3(6)
126.0(6)
171.1(12)
127.1(13)
ent molecules which are stereoisomers differing by mu-
tual disposition of the cyclopentadienyl and carbonyl
ligands in relation to the organometallic core. Phenyl
rings in the bridging ligand are perpendicular to each
other (angles between the planes are 94.2ꢁ and 93.7ꢁ
2.2. X-ray study of the complexes 2 and 9
The molecular structure of 2 is presented in Fig. 2.
The geometry of 2 is very close to that of the corre-
sponding manganese compound (g5-C5H5)(CO)2Mn@
C@C(H)Ph [6b]. All bond distance and angle values
(Table 1) are in a good agreement with those of analo-
gous rhenium compounds.
(a)
The molecular structure of 9 is presented in Fig. 3,
and selected bond distances and angles are given in
Table 2. The crystal unit cell of 9 contains two independ-
(b)
Fig. 2. Molecular structure of 2 (50% probability ellipsoids).
Fig. 3. Molecular structure of 9 (50% probability ellipsoids).

3842
D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
Table 2
sodium benzophenone-ketyl prior to use. Saturated
hydrocarbons, triethylamine, and dichloromethane were
freshly distilled from CaH2. Phenylacetylene was dis-
tilled in vacuo and stored under an argon atmosphere.
˚
Selected bond distances (A) and angles (ꢁ) for complex 9
Re(1)–C(1)
Re(1)–C(22)
Re(1)–C(23)
Re(1)–Cp
2.079(7)
1.861(9)
1.909(9)
1.945(8)
2.082(7)
1.892(9)
1.900(8)
1.946(8)
2.9031(5)
2.053(7)
1.856(9)
1.917(9)
1.952(8)
2.072(7)
Re(4)–C(60)
Re(4)–C(59)
Re(4)–Cp
1.870(9)
1.904(9)
1.957(8)
2.8999(4)
1.342(9)
1.437(11)
1.495(9)
1.185(10)
1.446(12)
1.373(10)
1.434(11)
1.498(10)
1.196(10)
1.447(11)
˚
Silica gel (70–230 mesh, 60 A) was obtained from Ald-
Re(3)–Re(4)
C(1)–C(2)
C(2)–C(3)
rich Chemical. The starting (g5-C5H5)Re(CO)3 was pre-
pared according to the described method [7]. The
reagents used were either prepared by described meth-
ods ((g5-C5H5)2FeBF4, AgBF4 Æ3(dioxane)) [8] or pur-
chased from Aldrich Chemical ((g5-C5H5)2Co).
Re(2)–C(1)
Re(2)–C(29)
Re(2)–C(30)
Re(2)–Cp
C(2)–C(5)
C(3)–C(4)
Re(1)–Re(2)
Re(3)–C(31)
Re(3)–C(52)
Re(3)–C(53)
Re(3)–Cp
C(4)–C(11)
C(31)–C(32)
C(32)–C(33)
C(32)–C(35)
C(33)–C(34)
C(34)–C(41)
All photochemical procedures were performed with
an immersed ultraviolet mercury lamp (125 W) under
low temperature conditions (ꢀ50 ‚ ꢀ15 ꢁC interval)
using ethanol/dry ice bath.
Re(4)–C(31)
Cyclic voltammograms were measured on a ‘‘PB-50-
1’’ instrument (Gomelꢀ, Belarus) in the dichloromethane
solution with a glassy carbon working electrode (S = 2
mm2), a platinum plate as an auxiliary electrode, and
a SCE as a reference. 0.1 M Bu4NPF6 was used as the
supporting electrolyte. All peak potentials are given rel-
ative to the ferrocene/ferrocenium couple (E = +0.46 V
vs. SCE, DE = 60 mV). The number of electrons con-
sumed was estimated by comparison of the currents of
the peaks observed with those of the one-electron deca-
methylferrocene/decamethylferrocenium couple of the
same concentrations.
C(1)–Re(1)–C(22)
C(1)–Re(1)–C(23)
C(2)–Re(1)–C(22)
C(2)–Re(1)–C(23)
C(22)–Re(1)–C(23)
C(1)–Re(1)–Re(2)
Cp–Re(1)–C(1)
83.0(3)
Cp–Re(2)–C(29)
Cp–Re(2)–C(30)
Cp–Re(2)–Re(1)
C(31)–Re(3)–C(52)
C(31)–Re(3)–C(53)
C(52)–Re(3)–C(53)
C(31)–Re(3)–Re(4)
C(52)–Re(3)–Re(4)
C(53)–Re(3)–Re(4)
Cp–Re(3)–C(31)
Cp–Re(3)–C(52)
Cp–Re(3)–C(53)
Cp–Re(3)–Re(4)
C(31)–Re(4)–C(59)
C(31)–Re(4)–C(60)
C(59)–Re(4)–C(60)
C(31)–Re(4)–Re(3)
C(1)–C(2)–C(5)
124.3(3)
124.1(3)
125.4(2)
83.1(3)
114.7(3)
99.7(2)
74.8(2)
83.4(4)
45.8(2)
114.7(3)
85.9(4)
45.6(2)
116.0(3)
127.4(3)
122.6(3)
129.3(2)
113.8(3)
81.2(3)
Cp–Re(1)–C(22)
Cp–Re(1)–C(23)
Cp–Re(1)–Re(2)
C(1)–Re(2)–C(29)
C(1)–Re(2)–C(30)
C(29)–Re(2)–C(30)
C(1)–Re(2)–Re(1)
C(29)–Re(2)–Re(1)
C(30)–Re(2)–Re(1)
Cp–Re(2)–C(1)
100.9(2)
74.5(2)
116.2(3)
125.3(3)
122.1(3)
130.2(2)
113.4(3)
81.2(3)
84.0(3)
45.7(2)
78.4(2)
Melting points were determined in sealed capillaries
under argon atmosphere. Solution IR spectra were
measured on Specord M80 (Carl Zeiss Jena) instrument
and given in cmꢀ1 with relative intensity in parenthesis.
105.5(2)
117.1(3)
79.2(2)
83.7(3)
45.1(2)
C(59)–Re(4)–Re(3)
C(60)–Re(4)–Re(3)
Cp–Re(4)–C(31)
Cp–Re(4)–C(59)
Cp–Re(4)–C(60)
Cp–Re(4)–Re(3)
C(2)–C(1)–Re(1)
C(2)–C(1)–Re(2)
Re(1)–C(1)–Re(2)
C(1)–C(2)–C(3)
124.1(7)
116.4(7)
178.4(9)
175.6(9)
137.8(5)
132.9(5)
89.3(3)
105.9(2)
117.1(3)
124.8(3)
124.2(3)
124.4(3)
136.7(5)
134.7(5)
88.5(3)
C(3)–C(2)–C(5)
C(2)–C(3)–C(4)
1
NMR H (400 MHz) and 13C (100 MHz) spectra were
obtained using a Bruker AMX 400 spectrometer and
referenced to residual solvent protons. Elemental analy-
ses were performed in the Laboratory of Microanalysis
of A.N. Nesmeyanov Institute of Organoelement Com-
pounds Russian Academy of Sciences. EI mass-spectra
(70 eV, 150 ꢁC) were obtained using a Kratos MS 890
spectrometer. All mass-spectral data are given for
187Re (correct isotope pattern was observed in all cases).
C(3)–C(4)–C(11)
C(32)–C(31)–Re(3)
C(32)–C(31)–Re(4)
Re(3)–C(31)–Re(4)
C(31)–C(32)–C(33)
C(31)–C(32)–C(35)
C(33)–C(32)–C(35)
120.1(7)
123.7(7)
116.1(7)
119.3(6)
for isomers a and b, respectively). The rhenium moieties
in molecules of 9 are in a transoid conformation (pseu-
do-torsional angles Cp(1)ꢁ ꢁ ꢁRe(1)–Re(2)ꢁ ꢁ ꢁCp(2) and
Cp(3)ꢁ ꢁ ꢁRe(3)–Re(4)ꢁ ꢁ ꢁCp(4) are 175.3ꢁ and ꢀ175.3ꢁ,
respectively). The cyclopentadienyl ligand planes are al-
most parallel (angles between planes are 4.7ꢁ and 6.6ꢁ);
cyclopentadienyl rings in the isomer a are in an eclipsed
conformation, and in the isomer b are rotated of each
other for 7.1ꢁ.
3.2. Preparation of (g5-C5H5)(CO)2Re@C@CHPh (2)
A vigorously stirred solution of 800 mg (2.4 mmol) of
(g5-C5H5)Re(CO)3(mCO 2016 (s), 1920 (vs) cmꢀ1) in 400–
500 ml of THF was irradiated at ꢀ50 ‚ ꢀ15 ꢁC for 50
min, affording (g5-C5H5)Re(CO)2(THF)(mCO 1904 (s),
1832 (s) cmꢀ1). Then 0.6 ml (0.5 mmol) of phenylacety-
lene was added and the reaction mixture was transferred
via cannula into a 0.5 L Schlenk flask. The mixture was
then refluxed until disappearance of bands of the alkyne
intermediate (g5-C5H5)Re(CO)2(g2-PhCBCH) (1) (mCO
1964 (s), 1880 (s) cmꢀ1) (18–22 h). The solvent was re-
moved in vacuo and the resulting red–brown oil was
chromatographed on silica (15 · 3 cm) under argon
atmosphere. Three main fractions were consequently
eluted with petroleum ether: colorless phenylacetylene
3. Experimental
3.1. General considerations
All operations were carried out under a purified ar-
gon atmosphere using Schlenk techniques. Reagent
grade benzene and THF were dried and distilled from

D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
3843
(discarded), colorless (g5-C5H5)Re(CO)3 (105 mg), and
rose (g5-C5H5)(CO)2Re@C@CHPh (2) (480 mg). 2 was
obtained (440 mg, 30%) as red crystals after recrystalli-
zation from hexane at ꢀ70 ꢁC.
J = 7.5 Hz, 2H ortho-Ph), signal of meta-Ph was over-
lapped with residual benzene protons. {1H} 13C NMR
(C6D6): d 47.2 (PhCBCH), 61.5 (PhCBCH), 83.7
(C5H5), 124.4, 126.5, 128.4 (Ph), 200.2 (Re–CO). MS
(EI) m/z: 410 (M+), 382 (M+ ꢀ CO), 354 (M+ ꢀ 2CO).
2: M.p. (from hexane) 82–83 ꢁC. Anal. Found: C,
44.46; H, 3.05. Calc. for C15H11O2Re: C, 44.01; H,
2.69%. IR (hexane, cmꢀ1): 2000 (s), 1932 (s) (mCO),
1648 (w), 1628 (br. w), 1596 (w) ( mC@C). 1H NMR
(C6D6): d 4.47 (s, 1H, @CAH), 4.86 (s, 5H, C5H5),
6.99 (t, J = 7.5 Hz, 1H, para-Ph), 7.28–7.18 (t overlap-
ping with residual benzene protons, J = 7.8 Hz, ꢂ2H,
meta-Ph), 7.32 (d, J = 7.5 Hz, 2H ortho-Ph). {1H} 13C
NMR (C6D6): d 85.6 (C5H5), 116.0 (Cb), 121.1, 121.6,
124.6 (Ph), 125.6 (ipso-Ph), 194.5 (Re–CO), 326.2 (Ca).
MS (EI) m/z: 410 (M+), 382 (M+ ꢀ CO), 354
(M+ ꢀ 2CO).
1
(g5-C5H5)Re(CO)3: H NMR (C6D6): d 5.72 (s, 5H,
C5H5). {1H} 13C NMR (C6D6): d 94.9 (C5H5), 207.7
(Re–CO).
1
3: H NMR (C6D6): d 4.71 (s, 1H, C@CH2), 4.94 (s,
5H, C5H5), 4.98 (s, 5H, C5H5), 5.14 (s, 1H, C@CH2),
signals of phenyl protons were not separated. {1H}
13C NMR (C6D6): d 84.0 (C@CH2), 85.7 (C5H5), 86.1
(C5H5), 121.2 (Cb), 122.5, 123.2, 124.6, (Ph), 140.2
(C@CH2), 192.5, 192.9 (Re–CO), 199.6, 201.0 (Re–CO).
4: 1H NMR (C6D6): d 4.40 (s, 5H, C5H5), 4.58 (s, 1H,
C@CHPh), 4.74 (s, 5H, C5H5), signals of phenyl protons
were not separated. {1H} 13C NMR (C6D6): d 82.4
(C5H5), 83.3 (C5H5).
3.3. Reaction of (g5-C5H5)(CO)2Re(THF) with
PhCBCH at room temperature
3.4. Oxidative dehydrodimerization of the complex 2
To a solution of (g5-C5H5)(CO)2Re(THF) generated
from 800 mg (2.4 mmol) of (g5-C5H5)Re(CO)3 as de-
scribed above 0.6 ml (0.5 mmol) of phenylacetylene
was added. The reaction mixture was concentrated to
50 ml and maintained at room temperature until the
bands of (g5-C5H5)(CO)2Re(THF) (mCO 1904 (s), 1832
(s) cmꢀ1) disappeared (30–36 h). During the reaction
course the bands of (g5-C5H5)(CO)2Re(g2-PhCBCH)
(1) (mCO 1964 (s), 1880 (s) cmꢀ1) were observed in IR
spectrum together with the bands of the side products
[6a]. The conditions used are optimal for preparation
of 1 because at lower temperature the reaction is very
slow and at higher temperature the rearrangement of
the product to the vinylidene 2 proceeds faster. After
the end of reaction the solvent was evaporated and the
residue was dried in vacuo to remove the excess of phe-
nylacetylene. The brown solid was extracted with hexane
(5 · 10 ml), the extract was filtered through Celite, con-
centrated to one-fifth of the initial volume, and cooled
to ꢀ20 ꢁC. The orange solid obtained consisted of the
complex 1 as the major component (ꢂ45% based on
integral intensity of C5H5 protons) together with the
unreacted (g5-C5H5)Re(CO)3 (ꢂ5%), the vinylidene
complex 2 (ꢂ11%), the binuclear vinylidene-alkene com-
pound {(g5-C5H5)(CO)2Re@C@C(Ph)AC(Ph)@CH2}
[Re(CO)2(g5-C5H5)] (3) (ꢂ25%), and the binuclear com-
plex with a bridging phenylvinylidene ligand [(g5-
C5H5)(CO)2Re]2(l-C@CHPh) (4) (ꢂ14%). The ratio of
total integral intensities of C5H5 protons and Ph protons
of listed compounds is close to 1:1. The isolation of pure
1 was not achieved neither by crystallization nor by col-
umn chromatography (fast decomposition of the target
complex 1 was observed during chromatography on sil-
ica and alumina).
A solution of 204 mg (0.5 mmol) of 2 and 0.15 ml (1
mmol) of triethylamine in 10 ml of dichloromethane was
treated with 136 mg (0.5 mmol) of (g5-C5H5)2FeBF4 at
room temperature. After 10 min the color of the solu-
tion changed from orange–red to red–brown and new
bands of the l-divinylidene complex 6 (1984 (s), 1916
(s) (mCO), 1612 (w), 1584 (w) (mC@C)) and the another di-
meric compound 9 (1944 (vs) (mCO)) appeared in the IR
spectrum instead of bands of the initial complex 2 (1992
(s), 1916 (s) (mCO), 1620 (w), 1588 (w) (mC@C)). The solu-
tion was evaporated to dryness and the residue was ex-
tracted with petroleum ether until the extracts were
colorless (6 · 10 ml). The combined extracts were con-
centrated and placed on a silica column (8 · 3 cm). Fer-
rocene was eluted with petroleum ether. Then the yellow
fraction of complex 9 was eluted with the 1:1 benzene/
petroleum ether mixture. Evaporation of the solvent
and recrystallization of the crude product from hexane
gave 45 mg (22%) of 9 as yellow crystals. The main di-
meric product 6 was thoroughly extracted with benzene
from the above residue and chromatographed (benzene).
The complex 6 was obtained (110 mg, 54%) as red
microcrystalline solid after solvent evaporation and
reprecipitation of the residue from THF with heptane
at ꢀ20 ꢁC.
6: M.p. (THF/heptane) 238 ꢁC (dec.) Anal. Found:
C, 44.45; H, 2.62. Calc. for C30H20O4Re2: C, 44.12;
H, 2.45%. IR (CH2Cl2, cmꢀ1): 1984 (s), 1916 (s)
(mCO), 1612 (w), 1584 (w) (mC@C). 1H NMR (THF-
d8): d 6.58 (s, 10H, C5H5) 7.71 (t, J = 7.5 Hz, 2H,
para-Ph), 7.96 (t, J = 7.8 Hz, 4H, meta-Ph), 8.15 (d,
J = 7.8 Hz, 4H ortho-Ph). {1H} 13C NMR (THF-d8):
d 91.5 (C5H5), 122.2, 126.2, 129.3 (Ph), 134.2 (Cb),
200.2 (Re–CO), 328.6 (Ca). MS (EI) m/z: 818 (M+),
706 (M+ ꢀ 4CO).
1
1: H NMR (C6D6): d 2.93 (s, 1H, CBCH), 4.70 (s,
5H, C5H5), 7.13 (t, J = 7.5 Hz, 1H, para-Ph), 7.76 (d,

3844
D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
9: M.p. (hexane) 164–165 ꢁC. Anal. Found: C, 44.65;
AgBF4 Æ3(dioxane) was added at ꢀ20 ꢁC. After 5 min
the deep brown solution of the radical cation 6+Å (2044
(s), 2024 (vs), 1980 (s) (mCO)) was obtained. The addition
of the second equivalent of the oxidant to the reaction
mixture led to the disappearance of the brown color
and a partial precipitation of the dicationic complex
62+ from the solution. After warming up to 0 ꢁC IR
spectrum of the solution contained the bands of the 2-
ene-1,4-diylidyne complex 62+ only (2100 (s), 2084 (s),
2048 (s), 2036 (s) (mCO)). Addition of cobaltocene (30–
40 mg) led to regeneration of the initial bis-vinylidene
complex 6 with nearly quantitative yield (estimated by
IR spectroscopy).
H, 2.86%. Calc. for C30H20O4Re2: C, 44.12; H, 2.45%.
IR (C6H6, cmꢀ1): 2176 (w) (mC@C), 1976 (m), 1940
(vs), 1904 (s), 1884 (m) (mCO), 1588 (w) (mCBC). 1H
NMR (C6D6) (the label A corresponds to the signals
of phenylethynyl moiety): d 4.58 (s, 5H, C5H5-A), 5.03
(s, 5H, C5H5-B) 6.99 (t, J = 7.45 Hz, 1H, para-Ph-A),
7.08 (t overlapped with another t signal, J = 7.45 Hz,
2H + 1H, meta-Ph-A + para-Ph-B), 7.24 (t, J = 7.4 Hz,
2H, meta-Ph-B), 7.59 (d, J = 6.95 Hz, 2H, ortho-Ph-
A), 7.76 (d, J = 7.8 Hz, 2H, ortho-Ph-B). {1H} 13C
NMR (C6D6): 88.3 (CBCPh), 89.0 (C5H5-A), 89.9
(C5H5-B), 96.1 (CBCPh), 125.5, 126.4, 127.4, 128.7,
129.3, 131.6, 140.5 (Ph), 144.9 (Cb), 200.1, 201.1,
201.4, 202.7 (Re–CO), 228.8 (Ca). MS (EI) m/z: 818
(M+), 706 (M+ ꢀ 4CO).
4. DFT calculations
3.5. Oxidation of the complex 2 with AgBF4 Æ3(dioxane)
followed by the reverse reduction of 2+ with cobaltocene
The calculations of the rhenium compounds 5Å, 6, 7, 9
and manganese compounds (g5-C5H5)(CO)2Mn@C@C
102 mg (0.25 mmol) of 2 in 10 ml of dichloromethane
was oxidized with 115 mg (0.25 mmol) of
AgBF4 Æ3(dioxane) at ꢀ20 ꢁC. The immediate change
of the reaction mixture color from orange-red to deep
red–violet was observed and new IR bands (2088 (s),
2032 (s) (mCO)) assigned to the radical cation 2+Å ap-
peared. Warming of the solution to ꢀ5 ‚ ꢀ0 ꢁC and stir-
ring at this temperature for 1 h caused no changes in IR
spectrum. An excess (80–100 mg) of a solid cobaltocene
was added and the solution was allowed to reach a room
temperature. The IR spectrum of the resulting solution
contained only the bands of the initial compound. The
vinylidene complex 2 (82 mg, 79%) was isolated after
chromatography as described above.
Table 3
Crystallographic Data for 2 and 9
Compound
2
9
Empirical formula
Formula weight
Temperature (K)
Crystal size (mm)
Crystal system
Space group
C15H11O2Re
409.44
173(2)
C30H20O4Re2
816.86
293(2)
0.50 · 0.50 · 0.08
Orthorhombic
Pbca
0.40 · 0.24 · 0.18
Monoclinic
P21/c
˚
a (A)
7.4866(15)
33.142(7)
10.370(2)
90
9.6157(9)
41.217(4)
13.2417(13)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90.487(3)
90
3
˚
V (A )
2573.0(9)
8
2.114
5247.9(9)
8
2.068
3.6. Deprotonation of the radical cation 2+ with triethyl-
amine
Z
dcalc (g cmꢀ3
F(000)
l (mmꢀ1
)
1536
9.435
3056
9.251
)
The radical cation 2+Å was generated as described
above from 204 mg (0.5 mmol) of 2 and 230 mg (0.5
mmol) of AgBF4 Æ3(dioxane) in 20 ml of dichlorometh-
ane and 0.15 ml (1 mmol) of triethylamine was added
in one portion to the resulted red–violet solution at
ꢀ20 ꢁC. The color of the solution became light yellow
in several seconds and after 5–10 min turned red–brown.
The IR spectral pattern was identical to that obtained
using ferrocenium salt as an oxidant (see above). After
usual chromatographic work up 43 mg (21%) of 9 and
125 mg (61%) of 6 were isolated.
h range (ꢁ)
Index range
2.32–28.05
0 ꢂ h ꢂ 9
0 ꢂ k ꢂ 43
ꢀ13 ꢂ l ꢂ 0
3004
1.83–28.22
ꢀ12 ꢂ h ꢂ 12
ꢀ54 ꢂ k ꢂ 54
ꢀ17 ꢂ l ꢂ 17
49602
Number of reflections
collected
Number of unique
reflections
3004
2482
12836
7771
Number of reflections with
I > 2r(I)
R1, wR2 [I > 2r(I)]
R1, wR2 (all data)
Data/restraints/parameters
GOF on F2
0.0853, 0.2375
0.0965, 0.2460
3004/0/163
1.044
0.0405, 0.0724
0.0800, 0.0778
2193/0/103
1.027
Maximum shift/error
Largestꢀd3ifference peak/hole
0.001
2.111/ꢀ2.808
0.001
1.818/ꢀ1.249
3.7. Stepwise oxidation of the l-divinylidene complex 6
˚
(e A
)
Absorption corrected,
Tmax, Tmin
None
0.287, 0.119
To the red solution of 6 (20 mg, 0.025 mmol) in 4 ml
of dichloromethane 12 mg (0.025 mmol) of

D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
3845
(Ph)AMn(CBCPh)(CO)2(g5-C5H5) and [(g5-C5H5)
6. Supporting information
(CO)2MnACBCPh]Å were performed at the density
functional B3LYP level of theory [9,10]. Optimized
geometry parameters and frequencies of normal vibra-
tional modes for the molecular systems studied were
computed employing the LanL2DZ atomic basis sets
[11,12]. The calculations were performed with the use
of the GAUSSIAN-98 program [13] on a CRAY J-90
supercomputer (National Energy Research Supercom-
puter Center, Oakland, CA, USA) and mini supercom-
Tables of atom coordinates, bond lengths and an-
gles, anisotropic displacement parameters for 2 and
9. Ordering information is given on any current mast-
head page.
Acknowledgement
puter
SC760-D
(Institute
of
Organoelement
This work was supported by Russian Foundation for
Basic Research (Project No. 02-03-33180), Program of
the Presidium of the Russian Academy of Sciences
587-03 and the Scientific School No. 1060.2003.3.
Compounds Russian Academy of Science, Moscow,
Russia).
4.1. X-ray structure determination
References
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3. The structures were determined by direct methods and
by full-matrix least squares refinement with anisotropic
thermal parameters for non-hydrogen atoms. The
hydrogen atoms were placed in calculated positions
and refined in riding model with fixed thermal parame-
ters. All calculations were carried out by use of the
SHELXTL PLUS (PC Version 5.0) program [15]. Crystal-
lographic data for 2 and 9 have been deposited with
the Cambridge Crystallographic Data Center, CCDC
Nos. 234739 and 234740, respectively. Copies of this
information may be obtained free of charge from the
Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +441223336033; e-mail deposit@ccdc.ca-
m.ac.uk or www.ccdc.cam.ac.uk).
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D.A. Valyaev et al. / Journal of Organometallic Chemistry 689 (2004) 3837–3846
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