Further chemistry of ruthenium butatrienylidene complexes

Article abstract of DOI:10.1016/j.jorganchem.2005.01.035

Several complexes have been obtained from reactions carried out in early attempts to prepare the diynyl complexes Ru(C≡CC≡CR)(dppe)Cp* (R = H, SiMe₃). These have been identified crystallographically as the acyl complex Ru{C≡CC(O)Me}(dppe)Cp* (3), the cationic imido complex [Ru{C≡CC(=NH₂)Me}(dppe)Cp*]PF₆ (4), the binuclear butenynylallenylidene [{Ru(dppe)Cp*}₂{μ- C≡CC(OMe)=CHCMe=C=C=}]PF₆ (5), and the bis(ethynyl) cyclobutenylidene [{Ru(dppe)Cp*}₂{μ-C≡CC ₄H₂(SiMe₃)C≡C}]PF₆ (6). NMR studies of 5 have revealed the existence of two isomers. Plausible routes for their formation from the putative butatrienylidene intermediate [Ru(=C=C=C=CH₂)(dppe)Cp*]⁺ (A) are discussed.

Full text of DOI:10.1016/j.jorganchem.2005.01.035

Journal of Organometallic Chemistry 690 (2005) 1772–1783
www.elsevier.com/locate/jorganchem
Further chemistry of ruthenium butatrienylidene complexes
a,
b
a,b
Michael I. Bruce *, Benjamin G. Ellis , Brian W. Skelton a,b, Allan H. White
a
Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
Chemistry M313, University of Western Australia, Crawley, Western Australia 6009, Australia
b
Received 27 October 2004; accepted 13 January 2005
Available online 17 March 2005
Abstract
Several complexes have been obtained from reactions carried out in early attempts to prepare the diynyl complexes
Ru(C„CC„CR)(dppe)Cp* (R = H, SiMe3). These have been identified crystallographically as the acyl complex Ru{C„CC(O)-
Me}(dppe)Cp* (3), the cationic imido complex [Ru{C„CC(@NH2)Me}(dppe)Cp*]PF6 (4), the binuclear butenynylallenylidene
[{Ru(dppe)Cp*}2{l-C„CC(OMe)@CHCMe@C@C@}]PF6 (5), and the bis(ethynyl)cyclobutenylidene [{Ru(dppe)Cp*}2{l-
C„CC4H2(SiMe3)C„C}]PF6 (6). NMR studies of 5 have revealed the existence of two isomers. Plausible routes for their formation
from the putative butatrienylidene intermediate [Ru(@C@C@C@CH2)(dppe)Cp*]+ (A) are discussed.
ꢀ 2005 Elsevier B.V. All rights reserved.
1. Introduction
Several groups have reported reactions which can be
rationalised as proceeding via butatrienylidene interme-
diates, formed in situ from reactions of 1,3-diynes with
electron-rich metal complexes containing labile ligands.
Most chemistry has been generated from trans-
[RuCl(@C@C@C@CH2)(dppm)2]+ [7] and [Ru(@C@
C@C@CH2)(PPh3)2Cp]+ [8] (from HC„CC„CH and
cis-RuCl2(dppm)2 or [Ru(thf)(PPh3)2Cp]+, respectively).
This paper describes further chemistry which is consid-
ered to arise from complexes analogous to the latter but
which, as in the earlier examples, have not been isolated.
The chemistry of metal r-alkynyl complexes and
their conjugate acids, the corresponding vinylidenes,
continues to provide novel routes into a wide variety
of organic systems [1]. The higher unsaturated carbenes,
such as allenylidenes, have also been developed to the
point where useful syntheses of metal-free molecules
can be achieved [2]. Not so well explored are the butatri-
enylidenes, which have been largely characterised on the
basis of their chemical reactions, the solid complexes
proving difficult to isolate [3]. Ruthenium carbonyl clus-
ter-stabilised examples of this ligand have been de-
scribed some years ago [4] and the first structurally
characterised mononuclear example was the iridium
2. Results
complex trans-IrClð@C@C@C@CPh2ÞðPPri3Þ [5]. The
2
2.1. Synthesis and characterisation of ruthenium
complexes with C4 chains
unusual metal-substituted derivative, [Fe{@C@C@
C@CH[Fp*(dppe)Cp*]}(CO)2Cp*]PF6, has been de-
scribed by Lapinte and coworkers [6].
2.1.1. Ru{C„CC(O)Me}(dppe)Cp* (3)
When the chloro-ruthenium complex RuCl(dppe)Cp*
(1) was treated with an excess of LiC„CC„CSiMe3 at
ꢀ78 ꢁC, in an attempt to synthesise Ru(C„CC„
CSiMe3)(dppe)Cp* (2), the only product was the hydride
RuH(dppe)Cp*. No evidence for the formation of 2 was
*
Corresponding author. Tel.: +61 8 8303 5939; fax: + 61 8 8303
4358.
E-mail address: michael.bruce@adelaide.edu.au (M.I. Bruce).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.01.035

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
1773
obtained. This result is in contrast to the analogous reac-
tion between RuCl(CO)2Cp and LiC„CC„CSiMe3,
which gave Ru(C„CC„CSiMe3)(CO)2Cp in a reason-
able yield (72%) [10]. This suggests that the carbonyl-
containing chloro complex is more susceptible to
nucleophilic attack than the much more electron-rich 1.
Theincreased steric hindrance imposedby thebulkyphos-
phine and Cp* ligands, relative to the smaller carbonyl
and Cp ligands, would also hinder nucleophilic attack.
The reaction of 1 with an excess of HC„CC„
CSiMe3 in the presence of [NH4]PF6 in MeOH resulted
in the initial orange suspension quickly changing to a
green solution. Work-up using a basic alumina column
gave bright yellow Ru{C„CC(O)Me}(dppe)Cp* (3;
Scheme 1) together with an intense blue fraction, dis-
cussed below. Characterisation of 3 was initially from
the single-crystal structure determination (see below)
and spectroscopic data [two m(CC) bands at 2024 and
2006, m(CO) at 1605 cmꢀ1, resonances for Cp* and
Me at dH 1.59 and 1.89, and dC 9.78, 32.37 and
93.71] also being consistent with this formulation.
The m(CC) frequencies are lower than those found in
the related complex Ru{C„CC(O)Me}(PPh3)2Cp
(2048, 2011 cmꢀ1) [11] as a result of the enhanced elec-
tron donating abilities of the Cp* and dppe ligands in
3. In the 13C NMR spectrum, signals for C(1) and C(2)
are found at d 159.24 (t) and 118.88(s). These data are
consistent with some stabilisation of resonance form 3b
by increased back-bonding into the allenylidene ligand,
although the upfield position of these resonances sug-
gests that resonance structure 3a is the major contrib-
utor to the overall structure.
2.1.2. [Ru{C„CC(@NH2)Me}(dppe)Cp*]PF6 (4)
It was anticipated that the reaction of 1 with an ex-
cess of Me3SiC„CC„CSiMe3 in the presence of KF
and [NH4]PF6 in MeOH solution might give
Ru(C„CC„CH)(dppe)Cp*. In this reaction, [NH4]PF6
was added to assist the dissociation of the Ru–Cl bond,
while KF was used both as a desilylating agent and a
source of base to ensure the deprotonation of the ex-
pected butatrienylidene intermediate A. The reaction
has been used with some success in earlier syntheses of
related alkynyl- and diynyl-ruthenium complexes [12].
As the reaction proceeded, the colour quickly changed
from the initial orange to a deep blue and then gradually
lightened to green. Work-up by preparative t.l.c. gave,
as the major product, an orange complex identified crys-
tallographically as [Ru{C„CC(@NH2)Me}(dppe)Cp*]-
PF6 (4; Scheme 1).
The IR spectrum of 4 contains two bands at 1982 and
1651 cmꢀ1 that were assigned to m(CC) and m(C@N),
+
Cp*(dppe)Ru Cl
R
C
C
C
C
SiMe3
(1)
[Cp*(dppe)Ru
C
C
C
CH2]+
(A)
KF / [NH4]PF6
(R = SiMe3)
[NH4]PF6
(R = H)
H2O
Me
Me
PF6
Cp*(dppe)Ru
C
C
C
Cp*(dppe)Ru
C
C
C
+
O
NH2
(3a)
(4a)
Me
Me
PF6
+
+
Cp*(dppe)Ru
C
C
C
Cp*(dppe)Ru
C
C
C
_
O
NH2
(3b)
(4b)
Scheme 1.

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M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
Scheme 2.
respectively, together with m(NH) bands between 3271
and 3449 cmꢀ1. In addition to the usual resonances,
the 13C NMR of 4 contains a triplet at d 216.37 [J(CP)
20 Hz], which is significantly downfield from the usual
value of d ca 120 found for Ru–C„ in related alky-
nyl-ruthenium complexes. Singlet resonances at d
121.72 and 156.74 are assigned to C(2) and C(3), respec-
tively, by comparison with related complexes [13].
Two interconverting resonance forms can describe
the structure of 4, as illustrated in Scheme 1. The relative
contributions of the alkynyl 4a and allenylidene 4b
forms in related complexes have been shown to depend
on the nature of the heteroatom and its ability to stabi-
lise the positive charge [13,14]. Generally, when the het-
eroatom is nitrogen, there are strong contributions from
resonance structure 4a. However, in the case of complex

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
1775
4, allenylidene form 4b would be stabilised by the elec-
tron-rich Ru(dppe)Cp* fragment, due to increased
back-bonding into the allenylidene ligand [13]. The spec-
troscopic and structural data (below) suggest that the
structure of 4 lies between these two extremes. The
observation of a m(C@N) band in the IR spectrum to-
gether with the X-ray data which establish bond lengths
close to the values expected for Ru–C single and C„C
triple bonds support the alkynyl form 4a. However, a
contribution from the allenylidene form 4b can be seen
in the 13C NMR spectrum, with resonances for the C1
and C2 atoms shifted significantly downfield with respect
to those found in Ru(C„CH)(dppe)Cp* [d 120.58 (C1),
92.99 (C2)] [9b].
chain were assigned to atoms C(2) (d 125.78/126/40),
C(3) (155.50/154.83), C(5) (122.42/119.56), C(6)
(142.55/141.61) and C(8) (150.21/146.28) using the
HSQC and HSBC experiments. All pairs have the same
56/44 relative intensities. We were not able to assign
definitively the resonances for the Ru-bonded carbons
C(1,7), for which four resonances in the region d
203.4–209.76 were observed. The chemical shifts of these
resonances lie between the characteristic vinylidene
Ru@C (d ca. 340.0) and alkynyl Ru-C„ (d ca. 120.0)
carbon resonances. The 31P NMR spectrum contained
two sets of signals for the dppe ligands (d 81.10 and
80.83/81.29 and 80.41) together with a single septet at
d ꢀ143.38 ([PF6]ꢀ).
Evidence for the stereochemical assignments is
found in the 2D ROESY NMR spectrum that con-
firmed the minor isomer had the Z configuration
around C(4)–C(5) with a ROESY interaction observed
between the proton directly attached to atom C(4) and
the methyl protons attached to C(51) (crystallographic
numbering). No such interaction was observed with the
major isomer, suggesting it has the E configuration.
HSQC 2D NMR confirmed that resonances at d
122.42, 58.03 and 26.17 found in the 13C NMR spec-
trum of the E isomer were due to C(4), C(31) and
C(51), respectively, with cross peaks being observed be-
tween the 1H and 13C resonances. Other resonances
were assigned upon the basis of long-range HMBC
2D NMR experiments.
2.2. Isolation and characterisation of ruthenium
complexes with C7 chains
2.2.1. [{Cp*(dppe)Ru}C„CC(OMe)@
CHCMe@C@C@{Ru(dppe)Cp*}]PF6 (5)
A feature of both the reactions described above is the
formation of intensely coloured blue products.That
accompanying 3 could be isolated using column chro-
matography (alumina), eluting with Et2O/acetone mix-
tures. An analytically pure sample was obtained after
a second chromatography and crystallisation (acetone–
hexane). The compound was identified as the cationic
binuclear product [{Cp*(dppe)Ru}C„CC(OMe)@
CHCMe@C@C@{Ru(dppe)Cp*}]PF6 (5; Scheme 2) by
a single-crystal X-ray structure determination coupled
with a detailed NMR study, which included HSQC
and HSBC experiments. The latter showed that an equi-
librium mixture of the E and Z isomers are present,
resulting from restricted rotation around the C(4)–C(5)
bond. Attempts to separate the isomers by t.l.c. were
not successful. While no changes in the relative ratios
were detected at low temperature (ꢀ80 ꢁC), coalescence
of the two resonances for the proton attached to C4 oc-
curs on heating the sample above 55 ꢁC.
2.2.2. [{Ru(dppe)Cp*}2{l-C„CC4H2-
(SiMe3)C„C}]PF6 (6)
A second deep blue product was isolated from the
reaction which afforded 3 and 5. Only formed in trace
quantities, it was first obtained whilst attempting to
crystallise a crude sample of 5 from CH2Cl2/hexane.
[Cp*(dppe)Ru
C
C
C
C
CH2]+
The NMR spectra of 5, including 2D HSQC and
HMBC NMR experiments, are consistent with the X-
ray structure and support the presence of the H, OMe
and Me pendant groups on the C7 bridging ligand.
Additionally, many of the resonances occur as pairs of
signals with constant relative intensities of 56/44 which,
as described below, are ascribed to E and Z isomers,
respectively [with respect to the C(4)@C(5) bond]. Thus,
(A)
Me3Si
C
C
C
Ru(dppe)Cp*
1
1
H
H
in the H NMR spectrum, two distinct H resonances
were found for the Cp* resonances (between d 1.58
and 1.62) and also for the @CH (d 5.44/5.14), OMe (d
3.24/2.87) and Me groups (d 1.69, 1.47) attached to the
bridging ligand. The 13C NMR spectrum similarly con-
tained pairs of signals at d 10.18/10.14 (C5Me5; only one
singlet found for each isomer), 97.04/96.84 and 96.31/
96.21 (C5Me5), 58.03/58.11 (OMe) and d 26.17/31.81
(CMe). Signals for various atoms in the substituted C7
C
Cp*(dppe)Ru
C
C
C
C
C
C
Ru(dppe)Cp*
+
C
SiMe3
(6)
Scheme 3.

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M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
Several block-like crystals were identified from the X-
ray structural study as the cyclobutenylidene complex
[{Ru(dppe)Cp*}2{l-C„CC4H2(SiMe3)C„C}]PF6 (6;
Scheme 3), a formulation supported by an ion in the
ES-MS at m/z 1440. A crude sample of 5 contained ions
corresponding to M+ at m/z 1401 (5) and at m/z 1440 (6).
MS–MS of the ion centred at m/z 1440 did not result in
fragmentation to give m/z 1401. Unfortunately, we have
212
211
222
221
031
P(2)
021
O(3)
02
03
04
1
2
20
3
041
112
Ru
05
10
P(1)
01
4
011
121
111
051
122
(a)
222
212
211
221
031
021
P(2)
02
01
03
N(3)
20
Ru
05
121
2
1
04
4
041
112
3
10
011
111
P(1)
051
122
(b)
Fig. 1. Plots of (a) a molecule of Ru{C„CC(O)Me}(dppe)Cp* (3) and (b) the cation of [Ru{C„CC(@NH2)Me}(dppe)Cp*]PF6 (4).

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
1777
been unable to make this complex by any rational ap-
proach, so that full characterisation, including spectro-
scopic studies, has not been possible. However, the
structural data (below), including the short Ru–C(1)
The structural data for 3 [Fig. 1(a)] are in agreement
with a major contribution from 3a to the molecular
˚
structure, with values for Ru–C(1) [1.979(3) A] and
˚
C(1)–C(2) [1.223(4) A] close to those expected for Ru–
˚
separation [1.929(6) A], are consistent with delocalisa-
tion of the positive charge across the C7 ligand as indi-
cated in Scheme 3.
C single and C„C triple bonds and similar to those
found in Ru{C„CC(O)Me}(PPh3)2Cp [11b]. The
RuC3 unit adopts an almost linear arrangement with an-
gles at C(1) and C(2) of 179.4(2)ꢁ and 170.1(2)ꢁ, respec-
tively (see Table 2).
Complexes 5 and 6 are closely related to those of the
analogous compounds 7 and 8 described by Dixneuf and
coworkers [15]. These were both obtained from trans-
RuCl(C„CC„CH)(dppe)2, the former by reaction of
the diynyl with the allenylidenes [RuCl(@C@C@C@
CR1CH2R2)(dppe)2]+ (R1 = Me, R2 = H; R1 = Ph,
R2 = H, Me), while 8 was formed by oxidation of the
diynyl with [FeCp2]PF6.
The cation of complex 4 [Fig. 1(b)] has relatively
˚
short Ru–C [1.942(3) A] and long C„C triple bonds
˚
[1.238(4) A] [compared with expected values of 2.01
˚
(Ru–C), 1.85 (Ru@C), 1.20 (C„C), 1.31 A (C@C)]
while, within the remainder of the ligand, C(3)–C(2,4)
˚
distances are 1.382 and 1.511(6) A and the C(3)–N(3)
˚
distance [1.307(4) A]. Again, these data are consistent
2.3. X-ray structure determinations
with a degree of multiple bonding intermediate between
forms 4a and 4b.
The X-ray determined structures of complexes 3–6 are
shown in Figs 1–4 and selected structural parameters are
presented in Table 1. The common Ru(dppe)Cp* frag-
ments are similar to others reported on earlier occasions
[9,10] and are characterised by Ru–P and mean Ru–
C(Cp*) distances of between 2.2684–2.2910(8) and
The structure proposed for 5 is consistent with an
X-ray study on crystals obtained by the slow diffusion
of hexane into a concentrated acetone solution. The
crystal is modelled in terms of only the Z isomer
(Fig. 2), disposed about a crystallographic inversion
centre so that two superimposed orientations of the
centre string with common Ru(dppe)Cp* sites are pres-
ent. In fact, the two arrangements are not strictly
superimposed since the Ru–C(1)–C(2)–C(3) sequence
is not linear [as required for a formulation where there
˚
2.25–2.26 A, respectively, with P–Ru–P and P(1,2)–
Ru–C(1) angles of between 82.70–83.67(6)ꢁ, and 79.5–
88.8(2)ꢁ, respectively. These values are all consistent with
pseudo-octahedral coordination about the Ru atom.
122
112
51
111
1021
102
P(1)
5
3
1011
101
10
Ru
1031
103
104
211
1
2
O(3)
105
31
212
P(2)
1051
222
221
1041
Fig. 2. Plot of a cation in [{Cp*(dppe)Ru}C„CC(OMe)@CHCMe@C@C@{Ru(dppe)Cp*}]PF6 (5) (one disordered component; the superimposed
aggregate is centrosymmetric).

1778
M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
011
051
122
021
04
01
03
031
05
Ru
5
041
112
2
1
3
P(1)
111
4
211
Si
226
21
10
216
20
Fig. 3. Plot of the cation in [{Ru(dppe)Cp*}2{l-C„CC4H2(SiMe3)C„C}]PF6 (6).
b
a
Fig. 4. Plot of the unit cell contents of 6, projected down c.
is a triple bond between atoms C(1)–C(2)], while the
elongated displacement ellipsoid for C(2) suggests that
two sites for this atom are unresolved. Further, there
are two components assigned as C(4) and O(3), which
Crystals of [{Ru(dppe)Cp*}2{l-C„CC4H2(SiMe3)-
C„C}]PF6 (6) contain a cation (Fig. 3) disposed astride
a crystallographic mirror plane, modelled as a central
cyclobutenylidenium group substituted on C(4) by a
SiMe3 group and on C(3) and C(30) by two
C„CRu(dppe)Cp* fragments; an interesting crystal
packing is found (Fig. 4), the anions and SiMe3 groups
being disposed about the crystallographic mirror plane
at y = 0.25, 0.75, and the rutheniums and associated li-
gands disposed about y = 0, 1/2. The two Cp* ligands
have a relative cisoid geometry about the two ruthenium
atoms. Within the four-membered ring, C(3)–C(4)
˚
are separated by 0.3 A, consistent with the two occu-
pancies depicted in Chart 1. The results of the structure
determination are consistent with the proposed highly
delocalised nature of the C7 bridging ligand [C–C dis-
˚
tances 1.214(6) and between 1.38 and 1.43(1) A for
C(3)–C(5)] and the presence of the pendant groups
OMe, Me and H. The two ruthenium centres are at-
tached to the hydrocarbon by Ru–C bonds [1.944(4)
˚
˚
˚
A] which are intermediate between Ru–C(sp) (alkynyl)
[1.44(1) A] is shorter than C(3)–C(5) [1.50(1) A], which
is consistent with partial multiple bond character for the
C(3)–C(4)–C(30) moiety. The bridging ligand is nearly lin-
ear and the four-membered ring is slightly distorted with
the C(3)–C(4) and C(3)–C(5) bonds being marginally dif-
and Ru@C(sp2) (vinylidene) lengths. Along the chain,
the C–C separations are 1.214(6), 1.502(10), 1.403(14)
˚
and 1.400(13) A. The angle at C(1) is close to linear
[176.1(4)ꢁ], while those at C(2) and C(3) are respec-
tively 144.9(7) and 127.9(7)ꢁ, resulting in apparent
bending of the chain, presumably an artefact of the dis-
order mentioned above.
˚
ferent. The separation C(1)–C(2) [1.229(6) A] is some-
what long for a conventional C„C triple bond and
2
C(2)–C(3) [1.352(9) A] short for a C(sp)–C(sp ) bond.
˚

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
1779
Table 1
˚
Selected bond distances (A) and angles (ꢁ)
3
4
5
6
ꢀ
Bond distances (A)
Ru–P(1)
Ru–P(2)
Ru–C(Cp*)a
(av.)
2.2830(6)
2.2684(6)
2.217–2.274(3)
2.25(2)
2.2910(8)
2.2705(8)
2.226–2.285(3)
2.26(2)
2.272(1)
2.281(1)
2.282(2)
2.284(2)
2.238–2.271(5)
2.257(14)
1.911
2.234–2.290(6)
2.26(2)
1.908
Ru–C(0)
Ru–C(1)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(3)–X(3)
1.902
1.979(3)
1.913
1.942(3)
1.944(4)
1.214(6)
1.929(6)
1.229(9)
1.352(9)
1.44(1)
1.223(4)
1.442(4)
1.238(4)
1.382(4)
1.502(10)
1.403(14)
1.401(9) [O]
1.492(5)
1.233(4) [O]
1.511(5)
1.307(4) [N]
Bond angles (ꢁ)
P(1)–Ru–P(2)
P(1)–Ru–C(1)
P(2)–Ru–C(1)
C(0)–Ru–P(1)
C(0)–Ru–P(2)
C(0)–Ru–C(1)
Ru–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(2)–C(3)–X(3)
C(4)–C(3)–X(3)
C(3)–C(4)–X
83.11(2)
84.73(6)
82.79(7)
134.1
82.70(3)
85.14(9)
85.01(9)
132.7
82.95(4)
87.7(1)
79.5(1)
83.67(6)
88.8(2)
81.9(2)
131.1
135.0
123.0
132.0
133.3
120.7
132.9
121.4
132.1
122.6
179.4(2)
170.1(2)
117.2(3)
121.6(3) [O(3)]
121.2 [O(3)]
178.4(3)
167.6(3)
120.4(3)
122.0(3) [N(3)]
117.6(3) [N(3)]
176.1(4)
144.9(7)
127.9(7)
112.5(7) [O(3)]
111.9(7) [O(3)]
129.4(7) [C(5)]
176.3(5)
172.6(7)
138.3(6)
131.6(6) [C(5)]
90.0(6) [C(5)]
133.5(4) [Si]
0
0
˚
For 5: C(5)–C(51) 1.498(14) A; C(1)–C(2)–C(5 ) 150.9(6), C(2 ,4)–C(5)–C(51) 124.4, 121.3(7)ꢁ (primes denoting inversion images). For 6: C(3)–C(5)
0
˚
1.50(1), C(4)–Si 1.89(1) A; C(3)–C(4,5)–C(3 ) 92.4, 87.5(7)ꢁ.
In no case is the wide range a consequence of a random distribution but, rather, a tilt of the ring plane toward the organic donor, as indicated by
the C(0)-Ru-X angles [C(0) is the centre of the C5 ring].
a
Table 2
Crystal data and refinement details
Compound
3
4
5
6
Formula
MW
C40H42OP2Ru
701.8
C40H44F6NP3Ru
846.8
C81H85F6OP5Ru2 Æ 2C3H6O
1661.7
C83H89F6P5Ru2Si
1585.7
Crystal system
Space group
Monoclinic
P21/n (#14)
10.3938(6)
23.172(1)
14.8125(9)
109.612(2)
3360
Monoclinic
P21/c (#14)
13.639(2)
14.919(2)
18.509(3)
92.488(2)
3763
Monoclinic
C2/c (#15)
29.315(5)
16.232(3)
17.833(3)
110.761(3)
7935
Orthorhombic
Pnma (#62)
19.854(2)
˚
a (A)
˚
b (A)
24.463(2)
17.122(1)
˚
c (A)
b (ꢁ)
3
˚
V (A )
8316
Z
4
1.387
5.9
4
1.495
6.0
4
1.391
5.4
4
1.266
5.3
Dc (g cmꢀ3
)
l (cmꢀ1
)
Crystal size (mm)
Tmin/max
0.35 · 0.12 · 0.10
0.90
58
0.25 · 0.20 · 0.10
0.84
58
0.28 · 0.28 · 0.11
0.83
53
0.12 · 0.10 · 0.07
0.81
58
2hmax (ꢁ)
Ntot
67,792
44,059
39,745
128,813
17302 (0.15)
6322
N (Rint
No
)
17514 (0.084)
9499
0.044
9535 (0.047)
6834
0.038
7855 (0.058)
6486
0.058
R
0.053
0.061 (0.4)
Rw (n)w
0.040 (0.4)
0.039 (0.4)
0.058 (3)
2.4. Electrochemistry
V (irreversible) (under our conditions, the FeCp2/
[FeCp2]+ couple is found at +0.46 V). This electro-
chemical behaviour is in accord with related complexes
recently reported [15b]. The initial oxidation of 3 is
presumably metal-centred, involving a Ru(II)/Ru(III)
The cyclic voltammogram of 3 shows a single
reversible reduction at E = ꢀ1.31 V and two oxidation
waves at E = +0.53 V (reversible) and at Epa = +1.06

1780
M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
Me
Me
C3
[Ru*] C1 C2
O3
[Ru*] C1 C2
C4H
C3
C3'
C(1)
C(2)
[Ru*]
HC4
C(2) C(1) [Ru*]
O3
C3'
Me
Me
[Ru*] = Ru(dppe)Cp*
Chart 1.
process, while the second irreversible wave is consis-
tent with the higher oxidised species undergoing fur-
ther chemical reactions. The well-defined single
reduction process is attributed to reduction of the
unsaturated C7 ligand.
readily occur with vinylidenes in the Ru(PP)Cp0 series,
because the phenyl groups of the PPh3 or dppe ligands
present on the ruthenium centre afford steric protection
to C(1) and C(2). Consequently, ready isolation of the
cationic vinylidene complexes [1,16] occurs even in the
presence of ammonium salts.
In contrast, the outer C(3) and C(4) atoms of but-
atrienylidene ligands are not so well protected. The
chemistry of butatrienylidene ligands is well under-
stood from both experimental and theoretical results,
which show the carbon atoms have alternating elec-
tron-poor and electron-rich character as they extend
3. Discussion
Alkynyl complexes are strong bases and are readily
protonated by the ammonium ion, for example, releas-
ing free NH3. Further reaction of the latter does not
[Ru] = trans-RuCl(dppe)2
[Ru]
C
C
C
C
H
+
R1
[Ru]
C
C
C
C
[FeCp2]+
CH2R2
+
H
C
+
[Ru]
[Ru]
R1
C
C
C
C
C
C
[Ru]
[Ru]
C
C
C
C
C
C
C
C
R2
Me
H
H
+
H
C
+
[Ru]
[Ru]
R1
C
C
C
C
C
C
[Ru]
[Ru]
C
C
C
C
C
C
C
C
R2
Me
H
H
(7) R1 = H, R2 = Me, Ph; R1 = Me, R2 = Ph
(8)
Scheme 4.

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
1781
out from the metal centre [14,17,18]. The formation of
all four complexes described here is ascribed to initial
formation of the reactive butatrienylidene complex A,
which subsequently reacts rapidly with various nucleo-
philes also present in the reaction mixture. Under the
reaction conditions used here, desilylation of the pro-
tected diynes would generate HC„CC„CH in situ,
even when this reaction was performed in the absence
of KF, where Fꢀ formed by the hydrolysis of the
PPFꢀ6 anion is the active reagent [19]. Coordination
of the diyne to the ruthenium centre follows to give
either A directly, or the diynyl complex which can be
protonated by the [NHEt3]+ or [NH4]+ cations also
present [1,16].
have been reported. Unfortunately, we have not been
able to confirm this reaction pathway by, for example,
protonation of the butadiynyl complex followed by
addition of a second equivalent of the diynyl complex.
While the reaction mixture rapidly acquires the deep
blue colour of 6, attempted purification of this material
gave only mixtures of as yet unidentified complexes,
although the mass spectrum of the solid product con-
tains an ion at m/z 1440, consistent with the presence
of 6 (or an isomeric product). While the small amount
of 6 obtained may also be consistent with its being
formed by oxidation by traces of air, we have been able
to obtain neither 6 nor any related species by partial
chemical oxidation of Ru(C„CC„CR)(dppe)Cp*
(R @ H, SiMe3) with [FeCp2]+.
Complex 3 is probably formed by nucleophilic attack
of trace amounts of water on
A to give the
hydroxy(vinylidene) cation which then transforms into
3 via proton migration. A similar reaction of NH3 with
A would afford the analogous ammonium cation 4
(Scheme 1).
4. Conclusion
Several products have been isolated during attempts
to make the diynyl complexes Ru(C„CC„CR)-
(dppe)Cp* (R = H or SiMe3). A combination of X-ray
structural studies with IR and NMR spectroscopy has
enabled their formulation as the acyl complex 3 and
the imido cation 4, both containing C4 chains, and the
butenynylallenylidene 5 and the bis(ethynyl)cyclobute-
nylidene 6, containing C7 chains, linking the two metal
centres. Plausible reaction pathways which might lead
to these compounds involving the intermediacy of but-
atrienylidene A in each case are discussed.
Complexes 5 and 6 have precedents in the chemistry
of the closely related RuCl(dppe)2 system studied by
Dixneuf and coworkers. They have described coupling
of the neutral butadiynyl trans-RuCl(C„CC„CH)-
(dppe)2 with the cationic allenylidenes trans-
[RuCl@C@C@CR1(CH2R2)(dppe)2]+ (obtained from
the corresponding propargylic alcohols) to give 7
(R = H, R0 = Me, Ph; R = Me, R0 = Ph), and the
formation of cyclobutenylidenium cations trans-
[{RuCl(dppe)2}2{l-C„CC4H3C„C)}]+ (8) by partial
oxidation of trans-RuCl(C„CC„CSiMe3)(dppe)2 with
[FeCp2]+. The proposed routes to these derivatives in-
volve (a) attack of the allenylidene at the Cc„Cd triple
bond of the diynyl and (b) a metal-assisted [2 + 2] cyclo-
addition of two Cc„Cd triple bonds of adjacent mole-
cules (Scheme 4).
5. Experimental
5.1. General experimental conditions
While it is attractive to incorporate these routes as a
rationalisation of the formation of 5 and 6, respectively,
their structures reveal that subsequent reactions have
also occurred. In neither reaction can we exclude forma-
tion and desilylation of intermediate SiMe3-containing
complexes. However, we are inclined to propose that
the reactive butatrienylidene A is attacked by methoxide
to give B. Attack of the electron-rich CH2 group at elec-
trophilic Cc of a second molecule of A affords binuclear
intermediate C. From this, 5 is formed by an allylic
hydrogen transfer (Scheme 2).
Complex 6 may be formed by the [2 + 2] cycloaddi-
tion of the C(3)@C(4) double bond of the butatrienylid-
ene A to the C(3)–C(4) triple bond of Ru(C„CC„
CSiMe3)(dppe)Cp* formed in the reaction mixture
(Scheme 3). Cycloaddition reactions between vinyli-
denes and acetylides are well known to generate
four-membered cyclic systems [14,20–23]. However, at
present, no [2 + 2] cycloaddition reactions at the
C(3)–C(4) double bond of an isolated butatrienylidene
All reactions were carried out under dry, high purity
argon using standard Schlenk techniques. Common
solvents were dried, distilled under argon and degassed
before use.
5.2. Instrumentation
Infrared spectra were obtained on a Bruker IFS28
FT-IR spectrometer. Nujol mull spectra were obtained
from samples mounted between NaCl discs. NMR spec-
tra were recorded on Bruker ACP300 instrument (1H at
300.13 MHz, 13C at 75.47 MHz, 31P at 121.503 MHz).
Samples were dissolved in CDCl3, unless otherwise sta-
ted, contained in 5 mm sample tubes. Chemical shifts
are given in ppm relative to internal tetramethylsilane
1
for H and 13C NMR spectra and external H3PO4 for
31P NMR spectra. ES mass spectra: VG Platform 2 or
Finnigan LCQ. Solutions were directly infused into the
instrument. Chemical aids to ionisation were used as re-
quired [24]. Cyclic voltammograms were recorded using

1782
M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
a PAR model 263 apparatus, a saturated calomel elec-
trode, and ferrocene as internal calibrant (FeCp2/
[FeCp2]+ = +0.46 V). Elemental analyses were per-
formed at CMAS, Belmont, Australia.
5.5. [{Cp*(dppe)Ru}{C@CC(OMe)@CHCMe@
C@C@}{Ru(dppe)Cp*}]PF6 (5)
The blue fraction obtained with 3 was further purified
by chromatography, elution with 1/9 acetone/diethyl
ether giving a bright blue band that was chromato-
graphed a second time, followed by crystallisation (ace-
tone/hexane) to give bright blue crystals of
[{Cp*(dppe)Ru}{C„CC(OMe)@CHCMe@C@C@}{Ru-
(dppe)Cp*}]PF6 (5) (57 mg, 12%). Anal. Calcd
(C81H85F6OP5Ru2): C, 62.95; H, 5.54. Found: C,
63.49; H, 5.27. IR (Nujol): m(CCC) 1959 s; m(PF) 841 s
5.3. Reagents
Na[BPh4] (Aldrich), and [NBu4]F (Aldrich) were used
as received. The compounds RuCl(PPh3)2Cp [25],
RuCl(dppe)Cp* [9b], [FeCp2]PF6 [26], HC„C-
C„CSiMe3 [27] and SiMe3C„CC„CSiMe3 [28] were
prepared using the cited methods.
cmꢀ1
.
ES-MS (MeOH, m/z): 1401, M+; 635,
5.3.1. Ru{C„CC(O)Me}(dppe)Cp* (3)
[Ru(dppe)Cp*]+.
HC„CC„CSiMe3 (78 mg, 0.60 mmol) was added to
a suspension of 1 (200 mg, 0.30 mmol) and [NH4]PF6
(98 mg, 0.60 mmol) in MeOH (10 ml) and the mixture
was stirred at r.t. for 3 h. Solvent was removed and
the residue extracted in CH2Cl2 and loaded onto a basic
alumina column (20 · 2 cm). Elution with Et2O gave a
light yellow band containing Ru{C„CC(O)Me}(dppe)-
Cp* (3) (106 mg, 50%). Anal. Calcd (C40H42P2ORu): C,
68.46; H, 5.96; M, 702. Found: C, 68.57; H, 6.08. IR
The NMR spectra contained peaks assigned to two
isomers present in a 56/44 ratio. Major E isomer in
CD2Cl2: 1H NMR: d 1.69 (s, 3H, Me), 3.24 (s, 3H,
OMe), 5.44 (s, 1H, CH). 13C NMR: d 10.18 (s, C5Me5),
26.17 (s, Me), 58.03 (s, OMe), 96.31, 97.04 (2s, C5Me5),
122.42 (s, C4), 127.81 (s, C2), 142.50 (s, C5), 150.21 (s,
C6), 155.50 (s, C3). 31P NMR: d 80.83 (s, dppe), 81.10
1
(s, dppe). Minor Z isomer: H NMR: d 1.47 (s, 3H,
Me), 2.87 (s, 3H, OMe), 5.14 (s, 1H, CH). 13C NMR: d
10.14 (s, C5Me5), 31.81 (s, Me), 58.11 (s, OMe), 96.21,
96.84 (2s, C5Me5), 119.56 (s, C4), 126.40 (s, C2), 141.61
(s, C5), 146.28 (s, C6), 154.83 (s, C3). 31P NMR: d 80.41
(s, dppe), 81.29 (s, dppe).
1
(nujol): m(CC) 2024m, 2006s; m(C@O) 1605s cmꢀ1. H
NMR: d 1.59 (s, 15H, Cp*), 1.89 (s, 3H, Me), 2.18,
2.78 (2m, 2 · 2H, CH2CH2), 7.20–7.71 (m, 20H, Ph).
13C NMR: d 9.78 (s, C5Me5), 29.11 (m, CH2CH2),
32.37 (s, Me), 93.71 (s, C5Me5), 118.88 (s, C2), 127.07–
Peaks that could not be individually assigned: 1H
NMR: d 1.58–1.62 (m, 4 · 15H, Cp*), 2.29, 2.66 (br,
16H, CH2CH2), 7.21–7.68 (m, 80H, Ph). 13C NMR: d
29.66 (m, CH2CH2), 127.38–137.11 (m, Ph), 203.40 [t,
2
137.85 (m, Ph), 159.24 [t, J (CP) 23 Hz, C1], 180.89
(s, CO). 31P NMR: d 80.81 (s, dppe). ES-MS (MeOH,
m/z): 703, [M + H]+; 635, [Ru(dppe)Cp*]+.
2
2
2J (CP) 22 Hz], 207.42 [t, J (CP) 20 Hz], 208.83 [t, J
2
5.4. [Ru{C„CC(@NH2Me}(dppe)Cp*]PF6 (4)
(CP) 21 Hz], 209.76 [t, J (CP) 22 Hz] (C1, C7). 31P
NMR: d ꢀ143.38 (septet, PFꢀ6 ).
Complex 1 (290 mg, 0.43 mmol), Me3SiC„CC„
CSiMe3 (84 mg, 0.43 mmol), KF (25 mg, 0.43 mmol)
and [NH4]PF6 (141 mg, 0.86 mmol) were dried under
vacuum for 10 min. MeOH (30 mL) was added and
the solution was heated at reflux point for 1 h, after
which the solvent was removed and the residue extracted
in CH2Cl2 and loaded onto preparative t.l.c. plates.
Development with acetone-hexane (1/1) gave a bright
yellow band (Rf 0.6) that was crystallised from CH2
Cl2/hexane to give [RuC„CC(@NH2)Me(dppe)Cp*]
PF6 (4) (245 mg, 67%). Anal. Calcd (C40 H44F6NP3Ru):
C, 56.73; H, 5.24; N, 1.65; M, 702 (cation). Found: C,
56.60; H, 5.21; N, 1.58. IR (nujol): m(NH) 3449w,
3357w, 3271w; m(CCC) 1982 (br); m(CN) 1651m; m(PF)
5.6. [{Ru(dppe)Cp*}2{l-C@CC4H2(SiMe3)C@C}]
PF6 (6)
This complex was found as crystalline blocks in the
solid obtained from attempts to isolate 5 from the prod-
ucts of reactions between 1 and Me3SiC„CC„CSiMe3
(above).
6. Structure determinations
Full spheres of diffraction data to the indicated limits
were measured at ca 153 K using a Bruker AXS CCD
area-detector instrument. Ntot reflections were merged
to N unique (Rint quoted) after ‘‘empirical’’/ multiscan
absorption correction (proprietary software), No with
F > 4r(F) being used in the full matrix least squares
refinement. All data were measured using monochro-
837s cmꢀ1 1H NMR: d 1.54 [t, 3J(HP) 2 Hz, 15H,
.
Cpa], 1.77 (s, 3H, Me), 2.24, 2.64 (2m, 2 · 2H,
CH2CH2), 7.39–7.47 (m, 20H, Ph). 13C NMR: d 9.76
(s, C5Me5), 26.15 (s, Me), 29.11 (m, PCH2), 96.22 (s,
C5Me5), 121.72 (s, Cc), 127.96ꢀ135.69 (m, Ph), 156.74
2
[s, C(@NH2)], 216.37 [t, J(CP)20 Hz, Ca]. 31P NMR:
matic Mo-Ka radiation, k = 0.71073 A. Anisotropic
˚
d ꢀ143.5 (septet, PFꢀ6 ), 80.30 (s, dppe). ES-MS (m/z):
thermal parameter forms were refined for the
non-hydrogen atoms, (x, y, z, UisoH being constrained
702, M+; 635, [Ru(dppe)Cp*]+.

M.I. Bruce et al. / Journal of Organometallic Chemistry 690 (2005) 1772–1783
[3] M.I. Bruce, Coord. Chem. Rev. 248 (2004) 1603.
1783
at estimated values. Conventional residuals R, Rw on |F|
are given [weights: (r2(F) + 0.000nwF2)ꢀ1 for nw, see Ta-
ble 2]. Neutral atom complex scattering factors were
used; computation used the XTAL 3.7 program system
[29]. Pertinent results are given in the Figures (which
show non-hydrogen atoms with 50% probability ampli-
tude displacement ellipsoids and hydrogen atoms with
[4] (a) C.J. Adams, M.I. Bruce, B.W. Skelton, A.H. White, Chem.
Commun. (1996) 2663;
(b) C.J. Adams, M.I. Bruce, B.W. Skelton, A.H. White, J. Orga-
nomet. Chem. 584 (1999) 254.
[5] K. Ilg, H. Werner, Angew. Chem. Int. Ed. 39 (2000) 1632.
[6] F. Coat, M. Guillemot, F. Paul, C. Lapinte, J. Organomet.
Chem. 578 (1999) 76.
[7] R.F. Winter, F.M. Hornung, Organometallics 16 (1997) 4248.
[8] (a) M.I. Bruce, P. Hinterding, P.J. Low, B.W. Skelton, A.H.
White, Chem. Commun. (1996) 1009;
˚
arbitrary radii of 0.1 A) and tables.
6.1. Variata
(b) M.I. Bruce, P. Hinterding, P.J. Low, B.W. Skelton, A.H.
White, J. Chem. Soc., Dalton Trans. (1998) 467.
[9] (a) M.I. Bruce, F. de Montigny, M. Jevric, C. Lapinte, B.W.
Skelton, M.E. Smith, A.H. White, J. Organomet. Chem. 689
(2004) 2860;
4. (x, y, z, Uiso)H were refined throughout.
5. As modelled in space group C 2/c, the molecules
are disposed about crystallographic inversion centres,
entailing superposition of disordered components in
the string C(3)–C(51) and associated substituents. In
particular, C(4), O(3) components were modelled as
(b) M.I. Bruce, B.G. Ellis, P.J. Low, B.W. Skelton, A.H. White,
Organometallics 22 (2003) 3184.
[10] M.I. Bruce, B.G. Ellis, M. Gaudio, C. Lapinte, G. Melino, F.
Paul, B.W. Skelton, M.E. Smith, L. Toupet, A.H. White, Dalton
Trans. (2004) 1601.
˚
individual fragments, separated by 0.325(9) A. Atom
[11] (a) M.I. Bruce, D.N. Duffy, M.G. Humphrey, A.G. Swincer,
J. Organomet. Chem. 282 (1985) 383;
C(2), with an elongated displacement ellipsoid, in keep-
ing with two closely disposed components, is insuscepti-
ble to meaningful resolution and refinement as such.
6. The central methylene group was assigned as such
in keeping with the chemistry, some uncertainty in the
crystallographic assignment a concomitant of rather
weak and meagre data.
(b) M.I. Bruce, P. Hinterding, E.R.T. Tiekink, B.W. Skelton,
A.H. White, J. Organomet. Chem. 450 (1993) 209.
[12] (a) M.I. Bruce, B.C. Hall, B.D. Kelly, P.J. Low, B.W. Skelton,
A.H. White, J. Chem. Soc., Dalton Trans. (1999) 3719;
(b) M.I. Bruce, B.D. Kelly, B.W. Skelton, A.H. White, J. Orga-
nomet. Chem. 604 (2000) 150.
[13] R.F. Winter, K.-W. Klinkhammer, S. Zalis, Organometallics 20
(2001) 1317.
[14] R.F. Winter, Eur. J. Inorg. Chem. (1999) 2121.
[15] (a) S. Rigaut, L. Le Pichon, D. Touchard, P.H. Dixneuf, J.-C.
Daran, Chem. Commun. (2001) 1206;
7. Supplementary material
(b) S. Rigaut, J. Massue, D. Touchard, J.-L. Fillaut, S. Gohlen,
P.H. Dixnuef, Angew. Chem. Int. Ed. 41 (2002) 4513;
(c) S. Rigaut, D. Touchard, P.H. Dixneuf, J. Organomet. Chem.
684 (2003) 68.
.cif files for the structure determinations (except struc-
ture factors) have been deposited with the Cambridge
Crystallographic Data Centre as CCDC 250010-250013
(complexes 3–6, respectively). Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax: +44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk
or www: http://www.ccdc.cam.ac.uk).
[16] R.M. Bullock, J. Am. Chem. Soc. 109 (1987) 8087.
[17] M.I. Bruce, Coord. Chem. Rev. 166 (1997) 91.
[18] N.M. Kostic, R.F. Fenske, Organometallics 1 (1982) 974.
´
´
[19] R. Fernandez-Galan, B.R. Manzano, A. Otero, M. Lanfranchi,
M.A. Pellinghelli, Inorg. Chem. 33 (1994) 2309.
[20] N.E. Kolobova, V.V. Skripkin, G.G. Aleksandrov, Yu.T. Struch-
kov, J. Organomet. Chem. 169 (1979) 293.
[21] B.E. Boland-Lussier, R.P. Hughes, Organometallics 1 (1982)
635.
Acknowledgements
[22] W. Weng, T. Bartik, M.T. Johnson, A.M. Arif, J.A. Gladysz,
Organometallics 14 (1995) 889.
Mass spectra were obtained with the kind assistance of
Professor B.K. Nicholson (University of Waikato, Ham-
ilton, New Zealand). We thank the Australian Research
Council for support of this work and Johnson Matthey
plc, Reading, UK, for a generous loan of RuCl3 Æ nH2O.
[23] (a) H. Fischer, F. Leroux, G. Roth, R. Stumpf, Organometallics
15 (1996) 3723;
(b) F. Leroux, R. Stumpf, H. Fischer, Eur. J. Inorg. Chem. (1998)
1225.
[24] W. Henderson, J.S. McIndoe, B.K. Nicholson, P.J. Dyson,
J. Chem. Soc., Dalton Trans. (1998) 519.
[25] M.I. Bruce, C. Hameister, A.G. Swincer, R.C. Wallis, Inorg.
Synth. 28 (1990) 270.
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