Cyanoacetylenes and cyanoacetylides: Versatile ligands in organometallic chemistry

Article abstract of DOI:10.1039/b306089f

The nitrile like lone pair of the cyanoacetylene PhC≡CCequiv;N (1) has been found to coordinate readily to the Ru(PPh₃)₂Cp fragment, to give [Ru(Nequiv;CCequiv;CPh)(PPh₃)₂Cp]PF ₆ (2) which may be cons

Full text of DOI:10.1039/b306089f

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Cyanoacetylenes and cyanoacetylides: versatile ligands in
organometallic chemistry
Richard L. Cordiner, Deborah Corcoran, Dmitri S. Yufit, Andrés E. Goeta,
Judith A. K. Howard and Paul J. Low*
Department of Chemistry, University of Durham, South Road, Durham, UK DH1 3LE.
E-mail: p.j.low@durham.ac.uk
Received 29th May 2003, Accepted 24th July 2003
First published as an Advance Article on the web 6th August 2003
᎐
᎐
᎐
The nitrile like lone pair of the cyanoacetylene PhC᎐CC᎐N (1) has been found to coordinate readily to the
᎐
᎐
᎐
Ru(PPh ) Cp fragment, to give [Ru(N᎐CC᎐CPh)(PPh ) Cp]PF (2) which may be considered as an “extended”
derivative of the more common benzonitrile complex [Ru(N᎐CPh)(PPh ) Cp]PF (3). Reaction of 1 with
[Co (CO) (dppm)] readily forms the µ,η complex [Co (µ,η -PhC C᎐N)(CO) (dppm)] (4), which reacts with
[RuCl(PPh ) Cp] to give the mixed metal species [{Co (µ,η -PhC C᎐N){Ru(PPh ) Cp}(CO) (µ-dppm)}]PF (5).
᎐
᎐
3
2
3
2
6
᎐
᎐
3
2
6
2
2
᎐
᎐
2
6
2
2
4
2
᎐
᎐
3
2
2
2
3
2
4
6
1
᎐
᎐
The η (N) bonded PhC᎐CC᎐N ligand is labile, being displaced by NCMe at ambient temperature to afford
᎐
᎐
[Ru(NCMe)(PPh3)2Cp]PF6, or by tcne to give trans-[{Ru(PPh3)2Cp}2(µ-tcne)}][PF6]2 (9). The metallocyanoacetylide
᎐
᎐
᎐
[Ru(C᎐CC᎐N)(PPh ) Cp] (6) was prepared by lithiation (BuLi) of [Ru(C᎐CH)(PPh ) Cp] followed by treatment with
᎐
᎐
᎐
3
2
3 2
PhOCN. Coordination of the metal fragments Ru(PPh3)2Cp or Fe(dppe)Cp to the N terminus in 6 occurs readily to
ϩ
᎐
᎐
give the homo- or hetero-bimetallic cations [{Cp(PPh ) Ru}(µ-C᎐CC᎐N){ML Cp}] , which were isolated as
᎐
᎐
3
2
2
the PF6 salts [ML2Cp = Ru(PPh3)2Cp (7); Fe(dppe)Cp (8)]. The crystal structures of 2–5, 7 and 9 are reported.
The electrochemical response of these complexes suggests there are considerable electronic interactions between
the heterometallic end-caps in 8 through the polarised C3N bridge.
As part of our interest in the preparation and properties of
Introduction
metal complexes containing unsaturated ligands,9 we have
undertaken a study of the coordination chemistry of the simple
᎐
᎐
᎐
Cyanoacetylenes RC᎐CC᎐N offer both an alkyne-π system and
a nitrile-like lone pair for bonding to metal centres and should
be useful in the assembly of multi-metallic complexes. The
᎐
᎐
᎐
cyanoacetylene PhC᎐CC᎐N, and the metallocyanoacetylide
᎐
᎐
᎐
᎐
[Ru(C᎐CC᎐N)(PPh ) Cp]. We now report the synthesis and
᎐
᎐
3
2
᎐
᎐
cyanoacetylene moiety, RC᎐CC᎐N, also bears a number of
᎐
᎐
molecular structures of a series of cyanoacetylene and cyano-
acetylide complexes via simple reaction schemes, and prelimin-
ary reactivity and electrochemical studies.
close structural and electronic relationships with nitriles,
Ϫ
᎐
᎐
᎐
RC᎐N, and the diynyl anion, [RC᎐CC᎐C] and comparisons of
᎐
᎐
᎐
Ϫ
᎐
᎐
the chemistry of the cyanoacetylide anion [C᎐CC᎐N] with
᎐
᎐
that of the ubiquitous cyanide ligand would be interesting.
However, somewhat surprisingly, the coordination chemistry of
cyanoacetylenes and the cyanoacetylide ligand has not been
thoroughly developed.
Results and discussion
Synthesis
In very early work, the alkyne moiety in cyanoacetylene was
found to coordinate in η2-fashion following reaction with
[IrCl(CO)(PPh3)2] and nickelocene,1 while related η2-complexes
Treatment of a solution of [RuCl(PPh3)2Cp] in methanol with
᎐
᎐
PhC᎐CC᎐N (1) and the halide abstracting agent NH PF
᎐
᎐
4
6
resulted in the formation of a bright yellow solution, from
᎐
᎐
᎐
of RC᎐CC᎐N systems (R = H, CN, Fe(CO) Cp) were prepared
which [Ru(NCC᎐CPh)(PPh ) Cp]PF (2) could be isolated as
᎐
᎐
᎐
2
3 2 6
in complimentary studies.2 The formation of σ-vinyl complexes
via insertion of cyanoacetylene into metal–hydride or metal–
sulfur bonds has also been described.3
bright yellow crystals in good yield (Scheme 1). The complex
salt, which has the obvious chemical and structural analogies
with the benzonitrile complex [Ru(NCPh)(PPh3)2Cp]PF6 (3),10
was characterised by the usual spectroscopic data, which
included sharp resonances in the NMR spectra at δ 4.52 (1H)
and 84.90 (13C) from the cyclopentadienyl ligand. The acetyl-
enic carbons of the cyanoacetylene ligand were observed as
singlets at δ 115.88 and 116.63 in the 13C NMR spectrum. In the
Simple η1(C)- and η1(N)- bonded cyanoacetylide com-
plexes are rare. Oxidative addition of dicyanoacetylene to
4
᎐
᎐
[Pt(C H )(PPh ) ] afforded [Pt(CN)(C᎐CC᎐N)(PPh ) ], while
᎐
᎐
2
4
3
2
3 2
᎐
᎐
[Fe(SMe)(CO) Cp] reacts with HC᎐CC᎐N to afford [Fe-
᎐
᎐
2
᎐
᎐
(C᎐CC᎐N)(CO) Cp] together with various products derived
᎐
᎐
2
from insertion of the cyanocarbon into the Fe–S bond.5 Com-
31P NMR spectrum, resonances at δ 41.86 and Ϫ143.02 (JPF
=
1
᎐
᎐
plexes containing multiple η -C᎐CC᎐N ligands have been pre-
713 Hz) were assigned to the phosphine ligands of the complex
and the PF6Ϫ counter ion, respectively. The complex gave rise to
an intense isotopic envelope from the complex cation at m/z 818
and the [Ru(PPh3)2Cp]ϩ fragment ion was observed at m/z 691
᎐
᎐
᎐
᎐
pared from the reaction of [Co(PPh ) Cp] with HC᎐CC᎐N,
᎐
᎐
3
2
᎐
᎐
which afforded the bis(acetylide) [Co(C᎐CC᎐N) (PPh )Cp]
᎐
᎐
2
3
᎐
᎐
together with the vinylacetylide [Co(C᎐CC᎐N){CH᎐CH-
᎐
᎐
᎐
(CN)}(PPh3)Cp],6 and from [NEt4]2[MCl4] (M = Ni, Pd, Pt)
in the positive ion electrospray mass spectrum (ES(ϩ)-MS).
7
᎐
᎐
᎐
᎐
᎐
with Me SnC᎐CC᎐N, which afforded [NEt ] [M(C᎐CC᎐N) ].
The IR spectrum contained a relatively strong ν(C᎐C) absorp-
᎐
᎐
᎐
᎐
᎐
3
4 2
4
The coordinating ability of the nitrogen lone-pair from the
cyanoacetylide ligand is relatively unexplored. The co-
tion band at 2141 cmϪ1, which may be compared with that of
the free ligand at 2145 cmϪ1, but no absorption arising from the
coordinated nitrile moiety was detected.
᎐
᎐
ordination complexes [Ru(N᎐CC᎐CR)(tpy)(bpy)][PF ] (tpy =
᎐
᎐
6 2
᎐
᎐
1,2Ј:6Ј:2Љ-terpyridine, bpy
=
2,2Ј=bipyridine), which were
Coordination to the alkyne-like π-system in PhC᎐CC᎐N
᎐
᎐
characterised on the basis of elemental analysis, electronic
spectroscopy and electrochemical (cyclic voltammetry)
methods, contain the only examples of η1(N) bonded cyano-
acetylene ligands reported to date.8
occurred readily upon reaction with the known alkyne seques-
tering agent [Co2(CO)6(dppm)] to give the dark red complex
[Co2(µ,η2-PhC2CN)(CO)4(dppm)] (4) (Scheme 1). In addition
to the NMR resonances arising from the aromatic groups, the
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
3541

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Scheme 1
᎐
complex exhibited the usual doublet of triplet resonances for
Sequential treatment of [Ru(C᎐CH)(PPh ) Cp] with BuLi, to
᎐
3 2
the CH2 group of the dppm ligand at δ 3.15 and 3.49 in the 1H
NMR spectrum. The 13C NMR spectrum was characterised by
a triplet resonance from the dppm methylene carbon at δ 36.58
(JCP = 21 Hz). The carbon nuclei of the Co2C2 cluster core were
found as triplets at 97.96 (JCP = 18 Hz) and 123.55 (JCP = 3 Hz).
The IR spectrum was dominated by the strong ν(CO) bands
between 1960–2037 cmϪ1, with a weaker ν(CN) band at 2156
cmϪ1. The ES(ϩ)-MS contained ions at m/z 1504 ([2M ϩ Na]ϩ)
and 764 ([M ϩ Na]ϩ).
generate the intermediate lithiated species [Ru(C᎐CLi)(PPh ) -
Cp], and phenylcyanate (PhOCN) afforded [Ru(C᎐CC᎐N)-
(PPh3)2Cp] (6) in good yield (65%) (Scheme 2). In addition to
the molecular ion in the ES(ϩ)-MS (m/z 764) and Cp reson-
ances in the 1H and 13C NMR spectra (δH 4.37, δC 86.68), three
13C resonances at 121.64, 107.75 and 83.08 ppm were observed,
᎐
᎐
3
2
᎐
᎐
᎐
᎐
and assigned to the carbons of the C3N ligand. In the IR spec-
Ϫ1
᎐
᎐
trum (Nujol), strong ν(C᎐C) (2000 cm ) and ν(C᎐N) (2180
᎐
᎐
cmϪ1) bands were observed. The product decomposes slowly in
solution, but was found to be stable for several months if kept
as a solid in a freezer.
With examples of cyanoacetylene ligands in both the η1(N)
and η2(alkyne) motifs established, we attempted to construct a
multi-metallic complex which featured both bonding modes.
The reaction of 2 with [Co2(CO)6(dppm)] resulted in the
formation of a dark red solution from which only 4 could be
isolated. However, when 4 was allowed to react with [RuCl-
(PPh3)2Cp] in the presence of NH4PF6, a bright red solution
Reaction of 6 with [RuCl(PPh3)2Cp] and NH4PF6 in meth-
anol resulted in a smooth conversion to the binuclear species
[{Ru(PPh ) Cp} (µ:η (C),η (N)–C᎐CC᎐N)]PF (7), which pre-
1
1
᎐
᎐
᎐
᎐
3
2
2
6
cipitated from the reaction mixture as a bright yellow powder
(Scheme 2). The spectroscopic data were in agreement with the
proposed formulation, and included an ion in the ES(ϩ)-MS
arising from the complex cation (m/z 1432), two Cp resonances
2
᎐
was obtained, from which [Co (µ-η -PhC C᎐N{Ru(PPh ) -
᎐
2
2
3 2
Cp})(CO)4(dppm)]PF6 (5) was isolated as a brick-red powder
(Scheme 1). The composition of the complex was established
spectroscopically while careful recrystallisation at low temper-
ature afforded red cube-shaped crystals of 5.
in each of H (4.47 and 4.35 ppm) and 13C (87.55 and 83.64
1
ppm) NMR, two phosphine resonances in the 31P NMR, in
Ϫ
addition to the septet expected from the PF6 counter ion and
the characteristic ν(C᎐C) (1985 cm ) and ν(C᎐N) (2196 cm
The 1H and 13C NMR spectra of 5 clearly indicated the form-
ation of the heterometallic species, with sharp singlets at δ 4.30
(1H) and 84.34 (13C) together with unresolved multiplet reson-
ances centred at 3.28 (1H), and 35.84 (13C) confirming the pres-
ence of both Cp and dppm ligands. The IR spectrum contained
the signature pattern from the carbonyl ligands but the ν(CN)
band was not observed. The mass spectrum was consistent with
the suspected bimetallic composition, and the complex cation
was observed as an isotopic envelope centred at m/z 1431.
As a µ,η1(C),η1(N) ligand, the cyanoacetylide anion could be
expected to transmit electronic information between metal
centres located at the C and N termini in much the same way as
the µ-CN ligand.11 However, the synthetic procedures for the
preparation of transition metal cyanoacetylide complexes
reported to date require the use of cyanoacetylene or dicyano-
acetylene, both of which are volatile compounds prone to rapid
polymerisation, or trialkyltin substituted cyanoacetylenes. The
)
Ϫ1
Ϫ1
᎐
᎐
᎐
᎐
bands in the IR spectrum.
An analogous procedure with [FeCl(dppe)Cp] led to the
formation of the heterobimetallic species [{Ru(PPh3)2Cp}-
(µ:η (C),η (N)–C᎐CC᎐N){Fe(dppe)Cp}](PF ) (8) as a pale,
1
1
᎐
᎐
᎐
᎐
6
reddish-brown powder (Scheme 2). ES(ϩ)-MS confirmed the
presence of the complex cation (m/z 1261) and two Cp reson-
ances were visible in both the H and 13C NMR spectra (4.24
1
and 4.20 ppm, and 87.22 and 79.16 ppm respectively). Both
ν(C᎐C) (1986 cm ) and ν(C᎐N) (2194 cmϪ1) bands were clearly
Ϫ1
᎐
᎐
᎐
᎐
visible in the IR spectrum. The relative differences in the IR
spectra of the mononuclear complex 6 and binuclear 7 and 8
are complicated by kinematic effects, as commonly observed in
µ-CN systems,12 making qualitative judgements about the
underlying electronic structure based upon this data alone
difficult.
᎐
᎐
limited availability of M(C᎐CC᎐N)L complexes has precluded
᎐
᎐
n
Reactivity
a detailed examination of this chemistry to date. We chose to
explore the possibility of cyanating a terminal acetylide ligand
directly as a simple synthetic route to these complexes.
By way of assessing the stability of the metal–NC3R linkage, a
sample of 2 was treated with one equivalent of NCMe in
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
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Scheme 2
CDCl3. Over the course of 24 h, the Cp signal due to 2 slowly
diminished, whilst a new resonance from [Ru(NCMe)(PPh3)2-
Cp]ϩ grew, the assignment of which was verified by comparison
with an authentic sample (Scheme 1). The metallocyano-
᎐
᎐
acetylide “ligand” [Ru(C᎐CC᎐N)(PPh ) Cp] was more difficult
᎐
᎐
3
2
to displace and there was no evidence of reaction between 7 and
NCMe (in CDCl3) at room temperature after 72 h.
Metal acetylide, diynyl and polyyndiyl complexes are known
to react readily with tetracyanoethylene (tcne) under mild con-
ditions to afford [2 ϩ 2] cyclisation products, which ring open to
afford highly conjugated cyanocarbon ligands.13 The tcne lig-
and has also been used as a η1(N) bonding ligand, and reactions
with oxidisable metal fragments often give products derived
from charge transfer processes with the ligand best formulated
as a tcne radical or dianion.14 Reaction of 2 with tcne at ambi-
ent temperature resulted in a rapid change in the colour of the
solution from yellow to dark blue, and after work-up the dark
blue complex trans-[{Ru(PPh3)2Cp}2(µ-tcne)][PF6]2 (9) was
obtained (64%) (Scheme 1). The spectroscopic data were
inconclusive with regards the formation of the mononuclear
species [Ru(tcne)(PPh3)2Cp]PF6, or the cis or trans forms of the
binuclear species 9. Recrystallisation from CHCl3 afforded sap-
phire blue crystals suitable for a single-crystal X-ray diffraction
study, which served to conclusively identify the compound and
the results of which are described in more detail below. The IR
Fig. 1 Molecular structure of the cation of 2, showing the atom
labelling scheme. In this and subsequent Figures, H-atoms have been
omitted for clarity.
spectrum of 9 showed the expected ν(C᎐N) (2139 cmϪ1) with a
᎐
᎐
shoulder at 2164 cmϪ1. The deep blue colour of this compound
(λmax 650 nm, ε 2900 MϪ1 cmϪ1) can be attributed to a charge
transfer transition. The ground state molecular structure (see
below) is consistent with a description of this compound in
terms of a simple dicationic tcne coordination product contain-
ing a neutral tcne ligand and the poorly oxidisable Ru(PPh3)2-
Cpϩ fragment.
significantly shorter than that in 3 [2, 2.002(4); 3, 2.037(1) Å].
Some other subtle variations arising from the differing steric
properties of the cyanocarbon ligands are apparent. For
example, while the Ru–N(1)–C(2)–C(3)–C(4) fragment in 2 is
essentially linear, the Ru(1)–N(1)–C(2) angle in 3 is 171.7(1)Њ,
no doubt a consequence of steric interactions between the
phenyl rings of the benzonitrile and phosphine ligands. The
relative orientation of the C(11–16) phenyl group in 3, which
appears to be dictated by the constraints of the phenyl groups
on the PPh3 ligands, is approximately orthogonal to that found
in the solid state structure of 2.
Molecular structures
The molecular structures of 2, the closely related benzonitrile
complex 3,10 the cobalt clusters 4 and 5, and the binuclear com-
plexes 7 and 9 have been determined. Crystallographic details
are summarised in Table 1, and selected bond lengths and
angles are given in Tables 2 and 3.
2
᎐
Complexes [Co (ꢀ-ꢁ -PhC C᎐N)(CO) (dppm)] (4) and
᎐
2
2
4
2
᎐
[Co (ꢀ-ꢁ -PhC C᎐N{Ru(PPh ) Cp})(CO) (dppm)]PF (5)
᎐
2
2
3
2
4
6
᎐
Complexes [Ru{NC(C᎐C) Ph}(PPh ) Cp]PF [n ؍ 0 (3), 1 (2)]
᎐
n
3
2
6
The structures of 4 (Fig. 3) and 5 (Fig. 4) indicate the co-
ordination of the cyanacetylene ligand to the dicobalt fragment
via the alkyne moiety in the usual µ,η2 fashion. In addition, Fig.
4 clearly demonstrates the capacity for the nitrile and alkyne
moieties to simultaneously coordinate different metal frag-
ments. The structural parameters are not unusual, although we
note that the Co(1)–Co(2) [2.4651(3) Å] and C(3)–C(4)
[1.370(2) Å] bond lengths in 4 are respectively at the shorter and
The complex cations are illustrated in Fig. 1 (2) and Fig. 2 (3).
The Ru(PPh3)2Cp fragment is similar in each case, and while the
Ru–P bond lengths [2.352(1) and 2.355(1) Å in 2; 2.334(1) and
2.335(1) Å in 3] are at the long end of the range usually
encountered, the geometry is generally unremarkable. The
differences in the N(1)–C(2) bond lengths in 2 and 3 fall within
the limits of precision, while the Ru(1)–N(1) separation in 2 is
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
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Fig. 2 Molecular structure of the cation in 3, showing the atom
labelling scheme.
Fig. 3 The structure and numbering scheme of compound 4.
longer ends of the range of bond lengths normally associated
with [Co2(µ,η2-alkyne)(CO)4(dppm)] complexes. The bond
lengths along the Ph–C2CN chains in 4 and 5 are identical, and
there are no differences in bond angles of significance. The
bonds between C(2), C(3) and C(4) in the cobalt complexes 4
and 5 are elongated in comparison to those in 2, a fact which is
attributed to the difference in hybridisation at C(3) and C(4).
More interesting are the torsion angles C(6)–Co(1)–Co(2)–
C(8) [Ϫ17.86(7)Њ], C(7)–Co(1)–Co(2)–C(9) [Ϫ36.1(1)Њ] and
P(3)–Co(1)–Co(2)–P(4) [Ϫ11.13(2)Њ] in 4, which are unusually
large when compared against a series of closely related struc-
tures [Co2(µ,η2-RC2C6H4X-4)(CO)4(dppm)] (X = H, NO2, CN,
NMe2).15 The ligand arrangement about the cobalt centres is
not as heavily distorted in 5, but shows some deviation from the
norm [C(7)–Co(1)–Co(2)–C(8) 5.0(2)Њ; C(6)–Co(1)–Co(2)–C(9)
25.6(3)Њ; P(3)–Co(1)–Co(2)–P(4) 8.85(4)Њ].
The cyanoacetylide bridged complex [{Ru(PPh3)2Cp}2-
1
1
᎐
᎐
(ꢀ: ꢁ (C):ꢁ (N)–C᎐CC᎐N)]PF (7)
᎐
᎐
6
The complex cation is illustrated in Fig. 5. The metal centres lie
in an approximately cis arrangement, but there is no crystallo-
graphically imposed symmetry element relating these moieties.
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
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Table 2 Selected bond lengths (Å) for 2–5, 7 and 9
2
3
4
5
7
9e
Ru(1)–N(1)
Ru(1)–P(1)
Ru(1)–P(2)
N(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(11)
Co(1)–Co(2)
2.002(4)
2.3547(14)
2.3521(14)
1.162(7)
1.365(8)
1.208(8)
1.430(8)
2.037(1)
2.3338(3)
2.3348(3)
1.145(2)
–
–
–
2.036(3)
2.3420(9)
2.3343(9)
1.162(4)
1.393(5)
1.382(5)
1.460(5)
2.4846(7)
1.999(3)/2.011(3)
2.3213(9)/2.3262(9)
2.3225(9)/2.3250(9)
1.198(5)
1.359(5)
1.192(5)
1.976(5)
2.342(2)
2.360(2)
1.153(2)
1.412(2)
1.370(2)
1.465(2)
2.4651(3)
1.151(7)b
1.411(7)c
1.393(11)d
1.440(2)a
a C(2)–C(11). b N(1)–C(1). c C(1)–C(2). d C(2)–C(2A). e Also C(2)–C(3) 1.432(8) Å, C(3)–N(2) 1.135(8) Å.
Table 3 Selected bond angles (Њ) for 2–5, 7 and 9
2
3
4
5
7
9e
P(1)–Ru(1)–P(2)
Ru(1)–N(1)–C(2)
N(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(11)
101.25(5)
177.4(4)
177.6(6)
175.9(7)
176.5(6)
97.46(1)
101.61(3)
166.8(3)
175.0(4)
137.4(3)
140.4(3)
99.20(3)/100.73(3)
166.9(3)/169.8(3)
176.1(4)/176.4(4)
95.56(6)
169.7(4)b
177.3(6)c
121.3(6)d
171.7(1)
177.8(2)a
174.5(2)
143.0(1)
141.3(1)
a N(1)–C(2)–C(11). b Ru(1)–N(1)–C(1). c N(1)–C(1)–C(2). d N(1)–C(2)–C(2A). e Also C(1)–C(2)–C(3) 119.3(5)Њ, C(2)–C(3)–N(2) 175.3(6)Њ.
Fig. 4 A plot of the molecular structure of the cation in 5, illustrating the labelling scheme.
Fig. 5 A plot of the cation in 7 illustrating the atom labelling scheme.
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
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Fig. 6 A plot of the dication 9 illustrating the atom labelling scheme.
The structure is therefore comparable with the thf solvate
(EoxЊ ϩ0.98 V) wave, the chemical reversibility of each wave
improving at lower temperatures. The electron withdrawing
influence of the CN moiety is evident when these redox poten-
tial are compared with the electrochemical response of the
closely related species [Co2(µ-HC2Ph)(CO)4(dppm)] [EЊred
Ϫ1.73 V; EЊox ϩ0.79 V]. Coordination of the cationic
ruthenium fragment to the pendent CN moiety in 5 results in a
shift in the reduction potential to Ϫ1.23 V, and an increase in
the chemical stability of the reduction product. Oxidation of 5
occurred at ϩ1.06 V, but this wave was almost totally chem-
ically irreversible. The tcne bridged bimetallic dication 9
underwent a single irreversible oxidation (Epa ϩ1.42 V). Evi-
dently, there is little electronic interaction between the formally
Ru() centres through the tcne bridge.
of the cis form of the diyndiyl complex [{Ru(PPh3)2Cp}2-
16
᎐
᎐
(µ-C᎐CC᎐C)], although a detailed discussion is hampered by
᎐
᎐
the crystallographic difficulties in resolving N(1) and C(4). The
best result of the refinement were obtained with 50 : 50 C : N
occupancy of the terminal atoms in the C3N chain, as described
in the Experimental section. The Ru(PPh3)2Cp fragments dis-
play the same general trends noted in the other complexes in
this work and elsewhere, with Ru–P bond lengths spanning a
narrow range in the range 2.313(9)–2.3263(9) Å and P–Ru–PЈ
bond angles of ca. 100Њ (Table 2). The bridging ligand itself
is quite linear, although there is a more pronounced bend at
the termini of the RuC3NRu chain, probably due to the steric
influence of the PPh3 ligands (Table 2).
The homobimetallic cyanoacetylide bridged species 7 gave
rise to two oxidation waves, which became reversible at Ϫ30 ЊC.
By comparison with 2 and 6, these waves can be confidently
assigned to the sequential oxidation of the metal centres at the
C (ϩ0.91 V) and N (ϩ1.43 V) termini. The similarlity of the
oxidation potentials to those of the model complexes 2 and 6,
implies little electronic communication between the two
ruthenium centres through the C3N ligand.
However, the heterometallic complex 8 displayed more inter-
esting electrochemical response with two reversible oxidation
waves at surprisingly low potentials (ϩ0.47, ϩ1.11 V). These
may be compared with the oxidation potentials of 7, and the
mono-nuclear species 6 (ϩ0.92 V) and [Fe(NCMe)(dppe)-
Cp][PF6] (10),19 which is reversibly oxidised at ϩ0.75 V,
provided we make the assumption that the relative solvation
energies of the various oxidation states of 6, 7, 8 and 10 are
similar. The trend in EЊ values requires a significant interaction
between the heterometallic end-groups via the polarised C3N
bridge. The simplest interpretation of the results would con-
sider the electrode potentials in 8 in terms of metal-centred
The tcne bridged complex trans-[{Ru(PPh3)2Cp}2(ꢀ-tcne)][PF6]2
(9)
The dication in 9 (Fig. 6) rests on a crystallographic centre of
inversion at the mid-point of the tcne C(2)᎐C(2A) double bond.
᎐
The P(1)–Ru–P(2) bond angles are relatively small [95.56(5)Њ],
but the other parameters associated with the Ru(PPh3)2Cp
fragments are not unusual. Of somewhat greater interest is the
geometry adopted by the formally charge neutral tcne ligand.
The general geometry of the tcne fragment is very similar to
that of the parent organic molecule,17 with no evident twisting
of the two halves of the tcne fragment [C(1)–C(2)–C(2A)–
C(3A) 1.6Њ]. The C(1)–C(2)–C(3) bond angle in 9 [119.3(5)Њ] is
comparable with that in tcne (ca. 116Њ). Similarly, the bond
lengths of the non-coordinated C(3)–N(2) [1.135(8) Å] and
C(2)–C(3) [1.432(8) Å] groups fall within the range of values
displayed by tcne in the solid state. The central C(2)–C(2A)
bond length [1.393(11) Å] is marginally longer than in tcne, for
which a value of about 1.35 Å is common. Coordination of the
metal fragment results in elongation of N(1)–C(1) [1.151(7) Å]
and a contraction of C(1)–C(2) [1.411(7) Å], which may argu-
ably be taken as evidence of an extended Ru–NC–CC–CN–Ru
conjugation pathway.
electrochemical events. The greater electron donating ability of
᎐
the Cp(PPh ) RuC᎐CCN “ligand” vs. NCMe results in a more
᎐
3
2
favourable oxidation potential of the Fe(dppe)Cp fragment.
However, the second oxidation, which is presumably more
heavily ruthenium centred, is some 0.4 V more favourable than
the corresponding process in the homometallic complex 7. This
indicates that the mono-oxidised form of the Fe(dppe)Cp
fragment can behave as an electron donating group and facili-
tate oxidation of the remote ruthenium centre.20 An alternate
interpretation would consider the electrochemical results in
Electrochemistry
Cyclic voltammetry studies were carried out on the complexes
2–9 as described in the Experimental section, with electrode
potentials quoted against an internal ferrocene (Fc/Fcϩ 0.46 V
vs. SCE) or decamethylferrocene (Fc*/Fc*ϩ Ϫ0.13V vs. SCE)
standard.18 The electrochemical response of 2 and 3 were char-
acterised by a single oxidation wave (2, Epa ϩ1.47 V; 3, EЊ
ϩ1.30 V), which in the case of 3 was as reversible as the internal
ferrocene standard. The carbon-bonded monometallic species 6
showed a single, reversible oxidation at ϩ0.92 V.
terms of the depopulation of a high lying HOMO derived from
᎐
the anti-bonding combination of the π(RuC᎐CCN) and d(Fe)
᎐
based fragment orbitals similar to that found in isoelectronic
butadiyndiyl systems.21 A more detailed study of the electronic
and magnetic properties of cyanoacetylide bridged complexes
in the various electrochemically detected oxidation states is
necessary to determine the extent to which either of these
The CV response of 4 at a glassy carbon electrode was char-
acterised by a reduction (EredЊ Ϫ1.40 V) as well as an oxidation
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
3546

View Article Online
interpretations are valid. Work in this direction, which falls
outside of the scope of this manuscript, is underway.
δ 3.15 (dt, 1H, CHP2), 3.49 (dt, 1H, CHP2), 7.06–7.70 (m, 24H,
Ph). 13C NMR: δ 205.89, 199.21 (2 × br, CO), 141.32–127.36
(m, Ph), 123.55 (t, JCP = 3 Hz, Co2C2), 97.96 (t, JCP = 18 Hz,
Co2C2), 36.58 (t, JCP = 21 Hz, PCH2P). 31P NMR: δ 39.92 (s,
dppm). ES(ϩ)-MS (m/z): 1504 [2M ϩ Na]ϩ; 764 [M ϩ Na]ϩ. IR
Conclusion
(cyclohexane): ν(C᎐N) 2167cmϪ1, ν(CO) 2040s, 2017s, 1990sh
᎐
We have shown that simple cyanoacetylenes are capable of sim-
᎐
cmϪ1
.
ultaneously acting as η1(N) and η2(C2) ligands to give stable
᎐
mixed-metal species. Cyanoacetylide complexes M(C᎐CCN)L
᎐
n
2
᎐
᎐
are readily prepared via cyanation of M(C᎐CH)L , and are in
[{Co (ꢀ,ꢁ -PhC C᎐N){Ru(PPh ) Cp}(CO) (ꢀ-dppm)}]PF (5)
᎐
n
᎐
2
2
3
2
4
6
turn capable of acting as ligands in their own right to form
µ-η1,η1 bridged bimetallic species. The inherently polarised
cyanoacetylide bridge is apparently capable of promoting elec-
tronic interactions between different metal centres. The revers-
ible redox behaviour and polarised electronic structures of
these species prompt interesting questions about the potential
of this class of compound to find application as organometallic
components in molecular electronics and in the construction of
metal-containing assemblies.
2
᎐
A
suspension of [Co (µ,η -PhC C᎐N)(CO) (µ-dppm)] (4)
᎐
2 2 4
(100 mg, 0.135 mmol), [RuCl(PPh3)2Cp] (97 mg, 0.135 mmol)
and NH4PF6 (22 mg, 0.135 mmol) in MeOH (20 ml) was heated
at reflux point for 2 h. After this time, the resulting dark red
solution was allowed to cool, the solvent removed and the resi-
due taken up in the minimum volume of CH2Cl2. Filtration of
the extract into hexane precipitated the product 5 as a brick-red
powder (160 mg, 75%). Crystals suitable for X-ray analysis were
obtained by slow diffusion of hexane in a CH2Cl2 solution at
Ϫ20 ЊC. Found: C, 60.13; H, 4.07; N, 0.99. C79H62P5F6O4-
Co2NRu requires: C, 60.16; H, 3.96; N, 0.89%. 1H NMR: δ 3.28
Experimental
(m, 2H, PCH2P), 4.30 (s, 5H, Cp), 7.12–7.25 (m, 62H, Ph). 13
C
General conditions
NMR: δ 205.89, 199.21 (2 × br, 2 × CO), 141.31–128.36 (m,
Ph), 123.56 (t, JCP = 3 Hz, Co2C2), 100.01 (s, Cp), 97.96 (t,
JCP = 19 Hz, Co2C2), 36.58 (t, JCP = 21 Hz, PCH2P). 31P NMR:
δ 42.00 (s, PPh3), 37.67 (s, dppm), Ϫ142.96 (septet, JPF = 711
Hz, [PF6]Ϫ). ES(ϩ)-MS (m/z): 1431 [Co2(µ,η2-C6H5C2CN)-
{Ru(PPh3)2Cp}(CO)4(dppm)]ϩ, 691 [Ru(PPh3)2Cp]ϩ. IR (cyclo-
hexane): ν(CO) 2040s, 2017s, 1990sh cmϪ1. IR (Nujol): ν(CO)
2037m, 2011s, 1985s, 1967sh.
23
The reagents [RuCl(PPh3)2Cp],22 Ru(C᎐CH)(PPh ) Cp,
᎐
᎐
3
2
[Ru(NCPh)(PPh3)2Cp]PF6
(3),10
[Co2(CO)6(dppm)],24
PhOCN,25 and PhC᎐CC᎐N (1) were prepared according to
25
᎐
᎐
᎐
᎐
the literature methods. Other reagents were purchased and used
as received. NMR spectra were recorded using solutions in
CDCl3 on Varian Mercury 200 (1H, 31P{H}) or 400 (13C{H})
spectrometers. IR spectra were collected using a Nicolet Avatar
spectrometer from samples mounted as Nujol mulls (NaCl) or
cyclohexane or CH2Cl2 solutions in a 0.5 mm pathlength solu-
tion cell fitted with CsF windows. Electronic spectra were
recorded using a Varian Cary 5 spectrophotometer. Elemental
analyses were performed in house. Electrochemical measure-
ments were recorded from solutions in CH2Cl2 containing
0.1 M NBu4BF4 as supporting electrolyte using Pt working,
counter and pseudo-reference electrodes and an EcoChemie
PGSTAT30. Potentials are referenced such that internal
ferrocene and decamethylferrocene standards have half-wave
potentials of 0.46 and Ϫ0.13 V, respectively.
᎐
᎐
᎐
[Ru(C᎐CC᎐N)(PPh ) Cp] (6)
᎐
3
2
An oven-dried, two-necked Schlenk flask was cooled under
nitrogen and fitted with a stirrer bar and a low-temperature
thermometer. The flask was charged with Ru(C᎐CH)(PPh ) Cp
᎐
᎐
3
2
(390 mg, 0.55 mmol) in 30 ml dry, distilled THF and cooled to
Ϫ70 ЊC. To this solution BunLi (0.4 ml of a 1.6 M solution in
hexane). This was added at such a rate as to prevent the temper-
ature from exceeding Ϫ60 ЊC. The solution was stirred for
10 min at this temperature, brought to Ϫ20 ЊC for 10 min to
ensure complete reaction, and cooled back to Ϫ70 ЊC. Neat
PhOCN (0.4 ml, 3.5 mmol) was added to the cooled solution
and the solution stirred for a further 30 min at Ϫ70 ЊC before
being allowed to come to room temperature. The solvent was
removed using a rotary evaporator to leave a dark-green residue
which was dissolved in the minimum amount of dichloro-
methane and micro-filtered into hexane. The resulting yellow–
green solid was collected and dried in vacuo to give the crude
product (400 mg, 0.54 mmol, 98%), which was sufficiently pure
for further reaction and electrochemical measurements. Solu-
tions of the complex slowly decomposed, which made attempts
to purify the material by recrystallisation difficult, and an
᎐
᎐
᎐
[Ru (N᎐CC᎐CC H )(PPh ) Cp]PF (2)
᎐
6
5
3
2
6
An oven-dried, two-necked Schlenk flask was charged with
᎐
᎐
[RuCl(PPh ) Cp] (247 mg, 0.341 mmol), PhC᎐CC᎐N (122 mg,
᎐
᎐
3
2
0.961 mmol), and NH4PF6 (212 mg, 1.30 mmol). The solids
were suspended in MeOH (20 ml) and heated at reflux under a
nitrogen atmosphere. After 30 min the yellow solution which
formed was allowed to cool to room temperature and then fur-
ther cooled using an ice-water bath. The resulting yellow pre-
cipitate was collected to give 2 as a yellow solid (0.211 g, 63%).
Found: C, 61.90; H, 4.13; N, 1.50. RuC50H40P3F6N requires: C,
1
1
accurate microanalysis was not obtained. H NMR (CDCl3):
62.37; H, 4.19; N, 1.45%. H NMR: δ 4.52 (s, 5H, Cp), 6.98–
δ 4.37 (s, 5H, Cp), 7.11–7.51 (m, 35H, Ph). 31P{H} NMR
(CDCl3): δ 49.77 (s, PPh3). 13C-{H} NMR (CDCl3): δ 137.86–
137.36 (m, Cipso, PPh3), 133.79 (t, JCC = 5.09 Hz, Cortho, PPh3),
129.33 (s, Cpara, PPh3), 127.87 (t, JCC = 4.84 Hz, Cmeta, PPh3),
7.57 (m, 40H, Ph). 13C NMR: δ 135.20–128.43 (m, Ph), 116.63,
115.88 (2 × s, C᎐C), 84.90 (s, Cp). 31P NMR: δ 41.86 (s, PPh3),
᎐
᎐
Ϫ143.02 (septet, JPF = 713 Hz, [PF6]Ϫ). ES(ϩ)-MS (m/z): 818
ϩ
[Ru(NCC᎐CC H )(PPh ) Cp] , 691 [Ru(PPh3)Cp]ϩ. IR
᎐
᎐
6
5
3
2
Ϫ1
᎐
᎐
121.64 (s, C ), 107.75 (s, C᎐N), 86.68 (s, Cp), 83.08 (s, C ).
(Nujol): ν(C᎐C) 2141 cm
.
᎐
α
β
᎐
ES(ϩ)-MS (m/z) 764.1 [M ϩ Na]ϩ; 742.1 [M ϩ H]ϩ; 691 [Ru-
ϩ
Ϫ1
[Co (ꢀ,ꢁ2-PhC C᎐N)(CO) (ꢀ-dppm)] (4)
3
2
2
2
᎐
᎐
(PPh ) Cp] . IR (CH Cl ): ν(C᎐N) 2180 cm , ν(C᎐C) 2000
᎐
᎐
᎐
2
2
4
cmϪ1
.
A solution of [Co2(CO)6(dppm)] (100 mg, 0.150 mmol) and
᎐
᎐
PhC᎐CC᎐N (18.9 mg, 0.147 mmol) in benzene (10 ml) was
᎐
᎐
1
1
᎐
᎐
᎐
[{Ru(PPh ) Cp} (ꢀ-ꢁ (C),ꢁ (N)-C᎐CC᎐N)](PF ) (7)
᎐
3
2
2
6
heated at reflux point under a nitrogen atmosphere. After 2 h
the dark red solution was allowed to cool to room temperature.
The solvent was removed and the residue recrystallised
(CH2Cl2–MeOH) to give dark red–black crystals of 4 (50 mg,
45%). Found: C, 60.17; H, 3.75; N, 2.08. C38H27Co2O4P2Nؒ
MeOH requires: C, 60.56; H, 3.67; N, 1.89%. IR (Nujol): ν(CN)
An oven-dried, two-necked Schlenk flask was cooled under
nitrogen and fitted with condenser and stirrer bar and charged
with [RuCl(PPh ) Cp] (100 mg, 0.138 mmol), [Ru(C᎐CC᎐N)-
(PPh3)2Cp] (102 mg, 0.138 mmol) and NH4PF6 (90 mg, 0.55
mmol). The solids were suspended in methanol (20 ml) and
heated at reflux. During the reflux the suspension became a pale
᎐
᎐
᎐
᎐
3
2
1
2156w; ν(CO) 2036m, 2009s, 1983s, 1960m cmϪ1. H NMR:
D a l t o n T r a n s . , 2 0 0 3 , 3 5 4 1 – 3 5 4 9
3547

View Article Online
yellow/green colour. After 90 min the reaction mixture was
allowed to cool to room temperature and then cooled further in
an ice-water bath. The pale yellow–green solid produced was
collected by filtration and dried in vacuo (141 mg, 0.090 mmol,
65%). Recrystallisation (CH2Cl2–MeOH) afforded the product
as bright yellow blocks of a tri-CH2Cl2 solvate. Found: C,
63.93; H, 4.58; N, 1.08. C85H70P5F6NRu2ؒ0.5CH2Cl2 requires:
rected for absorption by numerical integration based on meas-
urements and indexing of the crystal faces using SHELXTL
software29 (2, 4, 9) and by the multi-scan method based on
multiple scans of identical and Laue equivalent reflections
using the SADABS program.30 (3, 7). No absorption correction
was applied to data of 5. All structures were solved using Direct
Methods and refined by full-matrix least squares on F 2 using
SHELXTL.29
Hydrogen atoms were geometrically placed and allowed to
ride on their parent C atom with Uiso(H) = 1.2Ueq(C). Idealised
C–H distances were fixed at 0.95 Å for carbon atoms in
six-membered rings of 2, 3, 7 and 9 (0.93 Å in 5), 1.00 Å for the
C–H in the five-membered rings of 2, 3, 7 and 9 (0.98 Å in 5),
0.99 Å for the C–H’s in partially occupied and disordered di-
chloromethane molecules in 2 and 7, 0.97 Å for a CH2 unit and
C–H’s of a dichloromethane molecule in 5 and 1.00 Å for the
C–H in a chloroform molecule of 9. Hydrogen atoms for 4 were
located from difference Fourier maps and their positions and
isotropic atomic displacements parameters were refined. All
non-hydrogen atoms were refined with anisotropic atomic
displacement parameters.
1
C, 63.37; H, 4.38; N, 0.86%. H NMR (CDCl3): δ 4.36 (s, 5H,
Cp), 4.48 (s, 5H, Cp), 7.08–7.29 (m, 67H, Ph). 31P{H} NMR
(CDCl3): 48.92 (s, PPh3), 42.16 (s, PPh3), Ϫ143.05 (ht, JPF
=
,
712 Hz, PF6). 13C{H} NMR (CDCl3): δ 137.69–137.09 (m, Cipso
PPh3), 136.83–136.17 (m, Cipso, PPh3), 133.69 (t, JCC = 5.03 Hz,
Cortho, PPh3), 133.42 (t, JCC = 5.03 Hz, Cortho, PPh3), 130.02 (s,
Cpara, PPh3), 129.66 (s, Cpara, PPh3), 128.39 (t, JCC = 4.78 Hz,
Cmeta, PPh3), 127.96 (t, JCC = 4.78 Hz, Cmeta, PPh3), 117.07 (s,
᎐
C᎐N), 87.55 (s, Cp), 83.64 (s, Cp), 83.49 (s, C ). ES(ϩ)-MS
᎐
β
ϩ
ϩ
᎐
᎐
(m/z) 1432 [{Ru(PPh ) Cp} (C᎐CC᎐N)] ; 691 [Ru(PPh ) Cp] .
IR (CH Cl ): ν(C᎐N) 2197 cm , ν(C᎐C) 1986 cm
᎐
᎐
3
2
2
3 2
Ϫ1
Ϫ1
᎐
᎐
.
᎐
᎐
2
2
1
1
᎐
᎐
᎐
[{Ru(PPh ) Cp}(ꢀ-ꢁ (C),ꢁ (N)–C᎐CC᎐N){Fe(dppe)Cp}](PF )
᎐
3
2
6
(8)
The four-atomic bridge between metal atoms in 7 is dis-
ordered over two positions. The terminal atoms of this bridge
were refined using mixed (1 : 1) atomic scattering factors of C
and N. The PF6 anion in 9 is severely disordered. One of the Ph
groups of 9 is also disordered over two positions which were
refined with equal occupation factors.
CCDC reference numbers 188693–188696, 211648 and
211649.
See http://www.rsc.org/suppdata/dt/b3/b306089f/ for crystal-
lographic data in CIF or other electronic format.
An oven-dried, two-necked Schlenk flask was cooled under
nitrogen and fitted with a condenser and stirrer bar and charged
᎐
᎐
with [FeCl(dppe)Cp] (75 mg, 0.135 mmol), [Ru(C᎐CC᎐N)-
᎐
᎐
(PPh3)2Cp] (100 mg, 0.135 mmol) and NH4PF6 (88 mg, 0.54
mmol). The solids were suspended in methanol (20 ml) and the
reaction mixture heated at reflux point for 1 h. A pale orange/
brown precipitate rapidly formed in a dark solution. The solu-
tion was allowed to cool and the brick-red precipitate collected
by filtration and purified by precipitation of a concentrated
dichloromethane solution into hexane (84 mg, 0.0598 mmol,
44%). 1H NMR (CDCl3): δ 7.31–7.00 (m, 52H, Ph), 4.24 ϩ 4.20
(unresolved, 10H, Cp). 31P{H} NMR (CDCl3): 98.02 (s, PPh3),
48.76 (s, PPh3), Ϫ143.06 (ht, JPF = 712 Hz, PF6). 13C{H} NMR
(CDCl3): δ 137.45–137.09 (m, Cipso, PPh3), 133.69 (t, JCC = 5.28
Hz, Cortho, PPh3), 133.12 (t, unresolved, Cortho, dppe), 131.84 (t,
Acknowledgements
We wish to thank Professor Neil G. Connelly (University of
Bristol) for his encouragement and support in the pursuit of
this work. The authors gratefully acknowledge financial
support from the EPSRC and the Department of Chemistry,
Durham University. J. A. K. H. holds an EPSRC Senior
Research Fellowship. R. L. C. holds a postgraduate studentship
from the Durham DTA. Assistance from the EPSRC National
Mass Spectrometry Service Centre (Swansea) is gratefully
acknowledged, as is a generous loan of RuCl3ؒnH2O from
Johnson Matthey Plc (Reading, UK).
unresolved, Cortho, dppe), 130.80 (s, Cpara, dppe), 130.60 (s, Cpara
,
dppe), 129.67 (s, Cpara, PPh3), 129.12 (t, unresolved, Cmeta, dppe),
128.96 (t, unresolved, Cmeta, dppe), 127.92 (t, JCC = 4.78 Hz,
Cmeta, PPh3), 121.60 (s, Cα), 87.22 (s, Cp), 79.16 (s, Cp), 83.08 (s,
Cβ), 28.02 (t, JCP = 21.62 Hz, CH2, dppe). ES(ϩ)-MS (m/z):
ϩ
᎐
᎐
1260 [{Ru(PPh ) Cp}(C᎐CC᎐N){Fe(dppe)Cp}] ; 519 [Fe-
᎐
᎐
3
2
ϩ
Ϫ1
᎐
᎐
(dppe)Cp] . IR (CH Cl ): ν(C᎐N) 2194 cm , ν(C᎐C) 1986
᎐
᎐
2
2
cmϪ1
.
[{Ru(PPh3)2Cp}2(ꢀ-tcne)](PF6)2 (9)
References
᎐
᎐
᎐
A solution of [Ru(N᎐CC᎐CPh)(PPh ) Cp]PF (150 mg, 0.156
᎐
3
2
6
1 M. I. Bruce and M. Z. Iqbal, J. Organomet. Chem., 1969, 17, 469.
2 G. L. McClure and W. H. Baddley, J. Organomet. Chem., 1960, 25,
261; G. L. McClure and W. H. Baddley, J. Organomet. Chem., 1971,
27, 155; J. L. Kiplinger, A. M. Arif and T. G. Richmond,
Inorg. Chem., 1995, 34, 399.
3 H. Scordia, R. Kergoat, M. M. Kubicki, J. E. Guerchais and
P. L’Haridon, Organometallics, 1983, 2, 1681; H. Scordia,
R. Kergoat, M. M. Kubicki and J. E. Guerchais, J. Organomet.
Chem., 1983, 249, 371; M. M. Kubicki, R. Kergoat, J. E. Guerchais
and P. L’Haridon, J. Chem. Soc., Dalton. Trans., 1984, 1791;
M. Cariou, M. Etienne, J. E. Guerchais, R. Kergoat and M. M.
Kubicki, J. Organomet. Chem., 1987, 327, 393; G. E. Herberich and
W. Barlage, J. Organomet. Chem., 1987, 331, 63; M. M. Kubicki,
R. Kergoat, H. Scordia, L. C. Gomes de Lima, J. E. Guerchias and
P. L’Haridon, J. Organomet. Chem., 1988, 340, 41; G. E. Herberich,
U. Englert, M. Hoeveler and I. Savvopoulos, J. Organomet. Chem.,
1990, 399, 35.
mmol) in THF (10 ml) was treated with tetracyanoethylene
(tcne) (20 mg, 0.156 mmol) and the solution stirred at room
temperature for 15 min. The solution rapidly darkened and
after 15 min the solvent was removed. The resulting dark green
residue was dissolved in DCM and precipitated into diethyl
ether to give [{Ru(PPh3)2Cp}2(µ-tcne)](PF6)2 as a grey–green
solid which was recrystallised (CHCl3) to give the product as
sapphire-blue crystals (90 mg, 77%). 1H NMR (CDCl3): δ 7.66–
7.05 (m, Ph,); 4.58 (s, 5H, Cp). 31P{1H} NMR (CDCl3): δ 41.87
(s, PPh3), Ϫ142.45 (ht, JPF = 713 Hz, PF6). ES(ϩ)-MS (m/z):
818.2 [{Ru (PPh3)2Cp}2(µ-tcne)]ϩ; 691 [Ru(PPh3)2Cp]ϩ. IR
Ϫ1
᎐
(CH Cl ): ν(C᎐C) 2139, 2164sh cm
.
᎐
2
2
Crystallography
4 W. H. Baddley, C. Panattoni, G. Bandoli, D. A. Clemente and
U. Belluco, J. Am. Chem. Soc., 1971, 93, 5590.
5 R. Kergoat, M. M. Kubicki, L. C. Gomes de Lima, H. Scordia,
J. E. Guerchias and P. L’Haridon, J. Organomet. Chem., 1989, 367,
143.
Diffraction data were collected on a Bruker SMART-CCD
detector diffractometer using graphite monochromated Mo-Kα
radiation (λ = 0.71073 Å). Data collections were carried out at
120 K (2, 3, 5, 7, 9) and 110 K (4) using an Oxford Cryosystems
N2 open-flow gas cryostat.26 Cell parameters were determined
and refined using the SMART software27 and raw frame data
were integrated using the SAINT program.28 Data were cor-
6 R. Kergoat, L. C. Gomes de Lima, C. Jégat, N. Le Berre, M. M.
Kubicki, J. E. Guerchais and P. L’Haridon, J. Organomet. Chem.,
1990, 389, 71.
7 Y. Zhou, A. M. Arif and J. S. Miller, Chem. Commun., 1996, 1881.
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View Article Online
8 S. C. Rasmussen, S. E. Ronco, D. A. Mlsna, M. A. Billadeau,
W. T. Pennington, J. W. Kolis and J. D. Petersen, Inorg. Chem., 1995,
34, 821.
2000, 3939; W. Hibbs, D. K. Rittenberg, K. Sugiura, B. M. Burkhart,
B. G. Morin, A. M. Arif, L. Liable-Sands, A. L. Rheingold,
M. Sundaralingham, A. J. Epstein and J. S. Miller, Inorg. Chem.,
2001, 40, 1915; M. M. Olmstead, G. Speier and L. Szabó, J. Chem.
Soc., Chem. Commun., 1994, 541; F. A. Cotton and Y. Kim, J. Am.
Chem. Soc., 1993, 115, 8511; F. A. Cotton, Y. Kim and J. Lu,
Inorg. Chim. Acta, 1994, 221, 1.
9 For recent examples, see: P. J. Low, T. M. Hayes, K. A. Udachin,
A. E. Goeta, J. A. K. Howard, G. D. Enright and A. J. Carty,
J. Chem. Soc., Dalton Trans., 2002, 1455; M. A. Fox, M. A. J.
Paterson, C. Nervi, F. Galeotti, H. Puschmann, J. A. K. Howard
and P. J. Low, Chem. Commun., 2001, 1610; P. J. Low, A. J. Carty,
K. A. Udachin and G. D. Enright, Chem. Commun., 2001, 411; M. I.
Bruce, K. Costuas, J.-F. Halet, B. C. Hall, P. J. Low, B. K. Nicholson,
B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 2002,
383; M. I. Bruce, P. J. Low, M. Ke, B. D. Kelly, B. W. Skelton, M. E.
Smith, A. H. White and N. B. Witton, Aust. J. Chem., 2001, 54, 453.
10 G. S. Ashby, M. I. Bruce, I. B. Tomkins and R. C. Wallis, Aust. J.
Chem., 1979, 32, 1003.
15 T. J. Snaith, P. J. Low, R. Rousseau, H. Puschmann and J. A. K.
Howard, J. Chem. Soc., Dalton Trans, 2001, 292.
16 M. I. Bruce, B. C. Hall, B. D. Kelly, P. J. Low, B. W. Skelton and
A. H. White, J. Chem. Soc., Dalton Trans., 1999, 3719; M. I. Bruce,
P. Hinterding, E. R. T. Tiekink, B. W. Skelton and A. H. White,
J. Organomet. Chem., 1993, 450, 209.
17 H. Bock and K. Ruppert, Inorg. Chem., 1992, 31, 5094, and
references therein.
11 see, for example: K. R. Dunbar and R. A. Heintz, Prog.
Inorg. Chem., 1997, 19, 283; F. Scandola, R. Argazzi, C. A. Bignozzi,
C. Chiorboli, M. T. Indelli and M. A. Rampi, Coord. Chem. Rev.,
1993, 125, 283; D. F. Shriver, Struct. Bonding (Berlin), 1996, 1, 32;
P. V. Berhardt, B. P. Macpherson and M. Martinez, J. Chem. Soc.,
Dalton Trans, 2002, 1435; G. N. Richardson, U. Brand and
H. Vajrenkamp, Inorg. Chem., 1999, 38, 3070; N. G. Connelly,
O. M. Hicks, G. R. Lewis, A. G. Orpen and A. J. Wood,
Chem. Commun., 1998, 517; H. Vahrenkamp, A. Geiß and G. N.
Richardson, J. Chem. Soc., Dalton Trans., 1997, 3643; G. A. Stark,
A. M. Arif and J. A. Gladysz, Organometallics, 1997, 16, 2909.
12 N. Zhu and H. Vahrenkamp, Chem. Ber./Recueil, 1997, 130, 1241.
13 For examples and leading references, see: A. Davison and J. P. Solar,
J. Organomet. Chem., 1979, 166, C13; M. I. Bruce, P. J. Low, B. W.
Skelton and A. H. White, New J. Chem., 1998, 419; M. I. Bruce,
B. D. Kelly, B. W. Skelton and A. H. White, J. Organomet. Chem.,
2000, 604, 150; M. I. Bruce, M. Ke, P. J. Low, B. W. Skelton and
A. H. White, Organometallics, 1998, 17, 3539.
14 See, for example: A. G. Bunn, P. J. Carroll and B. B. Wayland, Inorg.
Chem., 1992, 31, 1297; G. T. Lee, J. C. Calabrese, C. Vazquez and
J. S. Miller, Inorg. Chem., 1993, 32, 377; S. Mikami, K. Sugiura,
T. Maruta, Y. Maeda, M. Ohba, N. Usuki, H. Okawa,
T. Akutagawa, S. Nishihara, T. Nakamura, K. Iwasaki,
N. Miyazaki, S. Hino, E. Asato, J. S. Miller and Y. Sakata, J. Chem.
Soc., Dalton Trans., 2001, 448; E. J. Brandon, A. M. Arif, B. M.
Burkhart and J. S. Miller, Inorg. Chem., 1998, 37, 2792; D. K.
Rittenberg, A. M. Arif and J. S. Miller, J. Chem. Soc., Dalton Trans,
18 N. G. Connelly and W. E. Geiger, Chem. Rev., 1996, 96, 877.
19 for closely related complexes and syntheses, see: J. Ruiz, M.-T.
Garland, E. Román and D. Astruc, J. Organomet. Chem., 1989, 377,
309; P. E. Riley, C. E. Capshew, R. Pettit and R. E. Davis, Inorg.
Chem., 1978, 17, 408; a sample of [FeCl(dppe)Cp] was dissolved in
NCMe, treated with NH4PF6 and allowed to stir for 2 h after which
time the resulting bright red solution was filtered, concentrated and
layered with diethyl ether to afford [Fe(NCMe)(dppe)Cp]PF6 as
bright red crystals in near quantitative yield.
20 F. Paul, W. E. Meyer, L. Toupet, H. Jiao, J. A. Gladysz and
C. Lapinte, J. Am. Chem. Soc., 2000, 122, 9405.
21 M. I. Bruce, P. J. Low, K. Costuas, J.-F. Halet, S. P. Best and
G. A. Heath, J. Am. Chem. Soc., 2000, 122, 1949.
22 M. I. Bruce, C. Hameister, A. G. Swincer and R. C. Wallis,
Inorg. Synth., 1990, 28, 270.
23 M. I. Bruce and G. A. Koutsantonis, Aust. J. Chem., 1991, 44, 207.
24 L. S. Chia and W. R. Cullen, Inorg. Chem., 1975, 14, 482.
25 R. E. Murray and G. Zweifel, Synthesis, 1980, 150.
26 J. Cosier and A. M. Glazer, J. Appl. Crystallogr., 1986, 19, 105.
27 Bruker: SMART-NT Data Collection Software Version 5.0. Bruker
Analytical X-ray Instruments Inc., Madison, WI, USA, 1998.
28 Bruker: SAINT-NT Data Reduction Software Version 5.0. Bruker
X-ray Analytical Instruments Inc., Madison, WI, USA, 1998.
29 Bruker: SHELXTL Version 5.1. Bruker Analytical X-ray
Instruments Inc., Madison, WI, USA, 1998.
30 G. M. Sheldrick, SADABS Empirical Absorption Correction
Program, University of Göttingen, Germany, 1998.
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