Syntheses, structures, some reactions, and electrochemical oxidation of ferrocenylethynyl complexes of iron, ruthenium, and osmium

Article abstract of DOI:10.1021/om050483l

The syntheses and characterizations of several complexes containing ferrocenylethynyl and ferrocene-1,1′-bis(ethynyl) groups attached to M(PP)Cp′ [M = Fe, Ru, PP = dppe, Cp′ = Cp*; M = Ru, Os, PP = (PPh₃)₂, dppe, Cp′ = Cp] are descri

Full text of DOI:10.1021/om050483l

Organometallics 2005, 24, 5241-5255
5241
Syntheses, Structures, Some Reactions, and
Electrochemical Oxidation of Ferrocenylethynyl
Complexes of Iron, Ruthenium, and Osmium
Michael I. Bruce,*,† Paul J. Low,*,‡ Frantisˇek Hartl,§ Paul A. Humphrey,†
Fre´de´ric de Montigny,†,| Martyn Jevric,† Claude Lapinte,| Gary J. Perkins,†
Rachel L. Roberts,‡ Brian W. Skelton, and Allan H. White
Department of Chemistry, University of Adelaide, South Australia 5005, Department of
Chemistry, University of Durham, South Road, Durham DH1 3LE, England, Van’t Hoff
Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV
Amsterdam, The Netherlands, UMR CNRS 6509, Institut de Chimie, Campus de Beaulieu,
Universite´ de Rennes 1, 35042 Rennes, France, and Chemistry M313, School of Biomedical,
Biomolecular and Chemical Sciences, University of Western Australia, Crawley,
Western Australia 6009
Received June 11, 2005
The syntheses and characterizations of several complexes containing ferrocenylethynyl
and ferrocene-1,1′-bis(ethynyl) groups attached to M(PP)Cp′ [M ) Fe, Ru, PP ) dppe, Cp′ )
Cp*; M ) Ru, Os, PP ) (PPh3)2, dppe, Cp′ ) Cp] are described. Reactions with tetracyano-
ethene have given either tetracyanobuta-1,3-dienyl or η3-allylic derivatives, while addition
of Me+ afforded the corresponding vinylidene derivatives. Some electrochemical measure-
ments are discussed in terms of electronic communication between the redox-active M(PP)-
Cp′ groups through the ferrocene nucleus. The molecular structures of 14 of these complexes
have been determined by crystallographic methods.
Introduction
been focused on complexes containing ferrocenyl groups,
and we have earlier published a study of complexes Fc-
(CtC)nW(CO)3Cp (n ) 1-4) (Fc ) ferrocenyl, Fe(η-
C5H4-)Cp) in which we showed that lengthening of the
carbon chain from two to eight carbons resulted in an
increase in oxidation potential of the ferrocenyl moiety.7
This is consistent with both a gradual increase in the
degree of electron transfer from the Fc nucleus to the
chain and the decreased σ-donor ability of the longer
carbon chains, i.e., the higher acidity of poly-ynes vs
acetylenes.
Complexes containing carbon chains end-capped by
various transition metal-ligand combinations have
been proposed as models for molecular wires.1 In this
context, interest centers on those compounds that
contain carbon chains end-capped by redox-active metal
centers, among which the MnX(dmpe)2,2 Re(NO)(PPh3)-
Cp*,3 Fe(CO)2Cp*,4 Fe(dppe)Cp*,5 and Ru(PP)Cp′ [Cp′
) Cp, PP ) (PPh3)2; Cp′ ) Cp*, PP ) dppe]6 (dppe )
1,2-bis(diphenylphosphino)ethane, PPh2CH2CH2PPh2)
systems have been most studied. Attention has also
End-capping of carbon chains with both Fc and
another redox-active group, such as those mentioned
above, has been reported previously in the systems
McCtCRu(PP)Cp′ [Mc ) Fc, Rc; PP ) (PPh3)2 (1), dppe
(2), dppf; Cp′ ) Cp, Cp*8 (dppf ) 1,1-bis(diphenylphos-
phino)ferrocene, Fe(η-C5H4PPh2)2; Rc ) ruthenocenyl,
Ru(η-C5H4-)Cp)]. Electrochemical and spectroscopic
studies showed that there is a considerable electronic
interaction between the two end-caps mediated by the
carbon chain, so that the radical cation derived from
one-electron oxidation displays some delocalized char-
acter. To date, no examples of ferrocene derivatives
* To whom correspondence should be addressed. Tel: +44 (0)191
334 2114. Fax: +44 (0)191 384 4737. E-mail: p.j.low@durham.ac.uk.
† University of Adelaide.
‡ University of Durham.
§ University of Amsterdam.
| Universite´ de Rennes 1.
University of Western Australia.
(1) Bruce, M. I.; Low, P. J. Adv. Organomet. Chem. 2004, 50, 231.
(2) Fernandez, F. J.; Venkatesan, K.; Blacque, O.; Alfonso, M.;
Schmalle, H. W.; Berke, H. Chem. Eur. J. 2003, 9, 6192.
(3) (a) Brady, M.; Weng, W.; Zhou, Y.; Seyler, J. W.; Amoroso, A. J.;
Arif, A. M.; Bohme, M.; Frenking, G.; Gladysz, J. A. J. Am. Chem. Soc.
1997, 119, 775. (b) Bartik, T.; Weng, W.; Ramsden, J. A.; Szafewrt, S.;
Falloon, S. B.; Arif, A. M.; Gladysz, J. A. J. Am. Chem. Soc. 1998, 120,
11071. (c) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger, M.; Gladysz,
J. A. J. Am. Chem. Soc. 2000, 122, 810.
(4) (a) Akita, M.; Moro-oka, Y. Bull. Chem. Soc. Jpn. 1995, 68, 420.
(b) Akita, M.; Chung, M.-C.; Sakurai, A.; Sugimoto, S.; Terada, M.;
Tanaka, M.; Moro-oka, Y. Organometallics 1997, 16, 4882. (c) Sakurai,
A.; Akita, M.; Moro-oka, Y. Organometallics 1999, 18, 3241. (d) Akita,
M.; Sakurai, A.; Chung, M.-C.; Moro-oka, Y. J. Organomet. Chem. 2003,
670, 2.
(5) Le Narvor, N.; Toupet, L.; Lapinte, C. J. Am. Chem. Soc. 1995,
117, 7129. (b) Coat, F.; Guillevic, M.-A.; Toupet, L.; Paul, F.; Lapinte,
C. Organometallics 1997, 16, 5988. (c) Guillemot, M.; Toupet, L.;
Lapinte, C. Organometallics 1998, 17, 1929. (d) Coat, F.; Paul, F.;
Lapinte, C.; Toupet, L.; Costuas, K.; Halet, J.-F. J. Organomet. Chem.
2003, 683, 368.
(6) (a) Bruce, M. I.; Low, P. J.; Costuas, K.; Halet, J.-F.; Best, S. P.;
Heath, G. A. J. Am. Chem. Soc. 2000, 122, 1949. (b) Bruce, M. I.; Kelly,
B. D.; Skelton, B. W.; White, A. H. J. Organomet. Chem. 2000, 604,
150. (c) Bruce, M. I.; Ellis, B. G.; Low, P. J.; Skelton, B. W.; White, A.
H. Organometallics 2003, 22, 3184.
(7) Bruce, M. I.; Smith, M. E.; Skelton, B. W.; White, A. H. J.
Organomet. Chem. 2001, 637-639, 484.
(8) (a) Sato, M.; Shintate, H.; Kawata, Y.; Sekino, M.; Katada, M.;
Kawata, S. Organometallics 1994, 13, 1956. (b) Sato, M.; Hayashi, Y.;
Kumakura, S.; Shimizu, N.; Katada, M.; Kawata, S. Organometallics
1996, 15, 721. (c) Sato, M.; Kawata, Y.; Shintate, H.; Habata, Y.;
Akabori, S.; Unoura, K. Organometallics 1997, 16, 1693.
10.1021/om050483l CCC: $30.25 © 2005 American Chemical Society
Publication on Web 09/23/2005

5242 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
Scheme 1
(1-Os), is of note. The acetylenic carbons (Table 2)
appear between δC 105-120 (Ru-CR), 82-82 (Os-CR),
and 104-109 (Câ), with CR showing a triplet J(CP)
coupling to the two 31P nuclei of the supporting phos-
phine ligand(s).
As the compound 1,1′-(HCtC)2Fc′ is rather unstable,9
a general approach to the synthesis of the disubstituted
ferrocenes was developed using the metallo-desilylation
reaction of alkynyltrimethylsilanes described earlier.10
Thus, reactions of 1,1′-(Me3SiCtC)2Fc′ with ruthenium
complexes RuCl(PP)Cp′ in MeOH or MeOH-thf mix-
tures in the presence of KF afforded 50-60% yields of
the corresponding complexes 1,1′-{Cp′(PP)RuCtC}2Fc′
[Cp′ ) Cp, PP ) (PPh3)2 (5), dppe (6); Cp′ ) Cp*, PP )
dppe (7)] (Scheme 2). The analogous iron complex, 1,1′-
{Cp*(dppe)FeCtC}2Fc′ (8), was also prepared and
isolated as orange crystals in 60% yield by a similar
reaction from FeCl(dppe)Cp*. These trimetallic com-
plexes were identified by spectroscopic methods and by
X-ray structural determinations of 5, 7, and 8. A
byproduct identified as 1-(Me3SiCtC)-1′-{Cp(dppe)-
RuCtC}Fc′ (9) was obtained in 11% yield from the
reaction that afforded 6, and the Cp* analogue 10 was
made directly (46% yield) by using half an equivalent
of RuCl(dppe)Cp* in a similar reaction.
containing two metal-ethynyl substituents have
been reported, and this paper reports on the use of
the 1,1′-ferrocenediyl unit (Fc′; ferrocene-1,1′-diyl,
Fe(η-C5H4-)2) as a bridge between two redox-active
metal centers. Also described are derivatives of these
alkynyl compounds formed by adding electrophiles, such
as the electron-deficient alkene tetracyanoethene (tcne)
and Me+, to the CtC triple bond.
Results and Discussion
For complexes 5-8, the ν(CtC) bands are found
between 2065 and 2080 cm-1 in their IR spectra. Singlet
RuCp resonances occur between δH 4.45 and 4.72, with
C5H4 protons from the ferrocenyl residues between δH
3.57 and 4.58: the latter move to higher frequency with
the more electron-rich ruthenium groups. The spectra
of the Cp* complexes 7, 8, and 10 contain the ring Me
resonances at δH 1.63-1.68. The SiMe3 groups in 9 and
10 resonated at δH 0.23 and 0.27, respectively. Only 10
proved soluble enough to obtain satisfactory 13C NMR
spectra, in which resonances appeared at δ 10.76 and
92.97 (Cp* Me and ring carbons), between 29.9 and 30.5,
and 127-140 (dppe CH2 and Ph), and at δ 69.8, 65.2
and 73.4, and 79.0 (Fe-Cp, CR, Câ, and Cipso of Fe-
C5H4). In all of the trimetallic complexes, 31P resonances
occur in characteristic regions, at δP ca. 52 for PPh3 and
80-85 (dppe), while in the ES mass spectra, isotopic
envelopes corresponding to M+ or [M + nH]n+ ions were
observed.
A modified synthesis of Ru(CtCFc)(PP)Cp′ [Cp′ ) Cp,
PP ) (PPh3)2 (1-Ru), dppm (2), dppe (3-Ru); Cp ) Cp*,
PP ) dppe (4)] was used, whereby a mixture of RuCl-
(PP)Cp′, FcCtCH, and Na[BPh4] was heated in reflux-
ing methanol, followed by addition of sodium methoxide
solution; for the synthesis of 2, thf-NEt3 (1/1) was used
to improve solubility with the amine also serving as a
base to deprotonate the vinylidene intermediate (Scheme
1). The osmium analogues of 1-Ru (1-Os) and 3-Ru (3-
Os) were prepared and characterized similarly, the
reactions requiring 2 h heating. The complexes were
obtained in 55-82% yields. While 1, 3-Ru, and 4 have
all been described previously,8 identification of all
complexes described herein has followed from their
spectroscopic properties (IR, NMR, ES mass), and the
structures of most were confirmed by X-ray determina-
tions. Correct elemental microanalyses were obtained
for all complexes described herein. In solution the IR
spectra contain ν(CtC) bands at ca. 2080 cm-1. The
NMR data for the known complexes agreed with the
previously reported values. In general, Cp resonances
were found at δΗ ca. 4.0 (FeCp) and 4.8 (RuCp) and δC
ca. 66-69 (FeCp), 80-86 (RuCp), and 78.6 (OsCp)
(Table 1). The substituted C5H4 groups of the ferrocene
moieties gave unresolved multiplets between δH 3.75
and 3.8 and two unresolved multiplets at δC ca. 66.5
and ca. 70.7; the ipso carbons of the ferrocenes were at
δ ca. 77-78. Resonances for the Ph groups of the
phosphine ligands and for the CH2 fragments of dppm
and dppe were located in the normal ranges, although
the large downfield shift of the 31P signal for the
coordinated PPh3 ligand, from δ 51.87 (1-Ru) to 2.93
Although 5 proved to be relatively insoluble in com-
mon solvents, the more soluble mono-oxidized species
[5]PF6 was readily obtained by reaction of 5 with [FeCp2]-
PF6 in a dichloromethane-benzene mixture. The au-
thenticity of [5]PF6 was confirmed by microanalysis. The
IR spectrum of [5]PF6 as a Nujol mull contained strong
ν(CC) and ν(PF) absorptions at 1993 and 841 cm-1
,
respectively, with the decrease in frequency of the ν-
(CC) band relative to that in neutral 5 [ν(CC) 2101, 2069
cm-1] suggesting some change in the Ru-C-C-Fc
(9) Doisneau, G.; Balavoine, G.; Fillebeen-Khan, T. J. Organomet.
Chem. 1992, 425, 113.
(10) Bruce, M. I.; Hall, B. C.; Kelly, B. D.; Low, P. J.; Skelton, B.
W.; White, A. H. J. Chem. Soc., Dalton Trans. 1999, 3719.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Table 1. Some 13C NMR Parameters (δ, J(CP)/Hz) for Fc′{CtCRu(PP)Cp′}2 Fragmentsa
dppm/dppe Fe-C5H4 Fe-Cp Fe-Cipso Ru-Cp/Cp* Ph
Organometallics, Vol. 24, No. 22, 2005 5243
complex
1-Rub
1-Osb
2c
66.98, 70.46
69.83
69.84
66.27
69.69
69.72
69.69
69.83
70.95
72.27
72.23
72.45
71.09
77.25
77.81
76.42
76.79
77.42
77.77
79.01
81.37
74.61
75.44
75.36
76.33
77.21
77.21
77.20
78.01
80.02
85.94t (2.0) 127.8-140.7
66.90, 70.74
81.99 (Os)
80.45
127.8-140.7
129.6-140.1
50.65t (21.4)
66.24, 70.21
3-Rub 28.72-29.34
66.75, 70.31
83.18t (2.3) 128.2-144.3
78.62t (2.3) 126.6-143.9
10.77, 92.91 127.8-140.4
10.76, 92.97 127.9-140.4
3-Osb
4b
30.05-30.67
29.91-30.53
29.90-30.51
66.66, 70.69
66.81, 70.19
10d
11
65.21, 71.52, 71.84, 73.43
65.00, 68.64, 71.14, 71.45
67.79, 70.66 71.88, 75.15
91.47
128.4-134.4
128.1-140.8
127.0-142.5
125.4-143.4
12
47.06t (22.2)
85.09
13-Ru 21.46-22.08, 26.69-27.25 68.10, 70.57, 71.62, 72.42, 75.19
13-Os 22.78-23.50, 28.93-29.75 68.19, 70.91, 71.84, 75.29
86.75
83.96 (Os)
8.35, 98.19 128.3-137.3
91.76
91.82
93.84
90.93
14
15
16
17
18
19
23.85-24.52, 25.21-25.89 68.20, 70.25, 70.38, 71.39
65.91, 72.36, 73.03, 75.60
128.5-134.4
128.5-134.4
125.4-136.4, 163.3-165.3
125.4-136.3, 163.2-165.1
67.92, 72.36, 73.03, 75.56
67.09, 69.84
65.41, 69.56
66.24, 68.55
26.84-27.48
28.13-29.67
9.87, 80.02 125.3-136.3, 163.3-165.3
a CDCl3 unless otherwise stated. b C6D6. c d8-Toluene. d SiMe3 δ 0.91.
Table 2. 13C NMR Parameters (δ, J(CP)/Hz) for Ethynyl, Dienyl, and Vinylidene Ligandsa
Alkynyls
C(1)
C(2)
1-Rub
1-Osb
2c
106.26t (25.7)
82.74t (17.8)
105.76t (25.8)
106.76t (26.4)
83.41t (18.6)
119.79t (25.2)
103.76, 122.12t (25.2)
109.20
104.13
107.39t (17.5)
107.29
102.15
104.50
90.34, 106.86
3-Rub
3-Osb
4b
10
tcne adducts
C(1)
other dienyl
CN
11
217.87d (13.3)
189.12
186.67d (4.0)
188.62m, 197.68m
222.58d (12.9)
216.28d (13.1)
217.20d (13.1)
67.48, 84.13d (8.4), 91.50
111.84, 115.94, 119.52d (7.6), 120.05
113.33, 115.34, 115.42, 119.85
12
70.26, 82.87, 91.64
13-Ru
13-Os
14
15
16
72.42, 75.44, 85.53
93.61t (2.6)
66.71, 79.58d (6.9), 98.35
26.86, 65.37d (3.0), 83.46, 84.99d (8.3)
26.97, 65.30d (2.6), 83.71, 84.50d (8.6)
113.51, 114.59, 115.22, 119.92
114.36, 115.99, 116.43, 121.90
112.32d (2.6), 118.00d (1.2), 119.58d (1.8)
111.58d (2.5), 115.58, 119.38d (7.4), 119.60
111.93d, (2.6) 115.55, 119.45d (7.4), 119.60
Vinylidenes
C(1)
C(2)
Me
17
18
19
354.56t (16.0)
353.89t (17.3)
349.61t (17.2)
119.41, 121.58
99.96, 119.20, 121.64
102.66, 116.46
12.06
9.10
9.87
a CDCl3 unless otherwise stated. b C6D6. c d8-Toluene.
Scheme 2
obtained as a result of the paramagnetic nature of this
compound.
Electron-deficient alkenes, such as tetracyanoethene
(tcne), readily add to CtC triple bonds adjacent to
transition metals to give tetracyano-cyclobutenyl or
-butadienyl complexes, or allylic (vinylcarbene) com-
plexes, according to conditions (Scheme 3).11-13 Alky-
nylferrocenes have recently been shown to undergo
similar reactions to give the corresponding s-cis-buta-
dienyl derivatives.14 Reactions between tcne and either
1 or 4 proceeded readily to give the allylic complexes
(11) Davison, A.; Solar, J. P. J. Organomet. Chem. 1979, C13, 166.
(12) (a) Bruce, M. I.; Hambley, T. W.; Snow, M. R.; Swincer, A. G.
Organometallics 1985, 4, 494. (b) Bruce, M. I.; Hambley, T. W.; Snow,
M. R.; Swincer, A. G. Organometallics 1985, 4, 500. (c) Bruce, M. I.;
Hambley, T. W.; Liddell, M. J.; Swincer, A. G.; Tiekink, E. R. T.
Organometallics 1990, 9, 2886. (d) Bruce, M. I.; Low, P. J.; Skelton,
B. W.; White, A. H. New J. Chem. 1998, 22, 419.
(13) Onitsuka, K.; Ose, N.; Ozawa, F.; Takahashi, S. J. Organomet.
Chem. 1999, 578, 169.
(14) Mochida, T.; Yamazaki, S. J. Chem. Soc., Dalton Trans. 2002,
3559.
system upon oxidation. The ES-MS contains a weak M+
at m/z 1614. No NMR spectra of [5]PF6 could be

5244 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
Scheme 3
Scheme 4
groups attached to CR. The skeletal carbons of the allylic
ligand resonate at δC ca. 65-67, 80-85, 85-91, and
218-223; the strong downfield shift of the latter is
consistent with the presence of multiple-bond character
in the Ru-C(2) bond revealed by the X-ray structure.
In the η1-dienyl complexes 12 and 13, a resonance at δ
ca. 187-190 is also assigned to C(2), being deshielded
by both the electron-rich metal center and the electron-
withdrawing dC(CN)2 group. Atom C(3) resonates at δ
ca. 91-93, while the other skeletal carbons of the dienyl
group are found between δ ca. 70 and 75. The ES mass
spectra were generally obtained from solutions contain-
ing NaOMe, used to enhance ionization,15 and contained
the ions [M + Na]+ or, in the case of 12 and 14, [2M +
Na]+.
Further characterization was achieved from X-ray
structural determinations for 11, 13-Ru/Os, and 14, the
latter confirming the presence of the monodentate
dppe-P ligand. Also revealed was the presence of an
“impurity” that cocrystallized with 14 with essentially
the same structure, but with an oxygen attached to P(2).
While we were not able to assign a ν(PO) band in the
IR spectrum of 14 with any confidence, re-examination
of the crystallographic sample by 31P NMR spectroscopy
revealed the presence of a second resonance at δ 34.30
[J(PP) 28.7 Hz], assigned to the PdO group.
The reaction between 5 and 2 equiv of tcne afforded
an inseparable diastereomeric mixture of two conform-
ers (15 and 16) of the allylic complex (Scheme 4). After
heating the mixture in refluxing benzene for 2 days,
isomerization of 15 occurred to give exclusively 16.
Confirmation of the structure proposed on the basis of
elemental microanalyses and their 1H NMR spectra
(only one PPh3 ligand present) was obtained by a single-
crystal X-ray structural determination of 16. The two
diastereomers differ in the relative stereochemistries
about the two Ru centers. For 16, both CN groups of
the dC(CN)2 group are on the same face, whereas for
11 and 14, respectively, whereas similar reactions with
2, 3-Ru/Os gave the butadienyls 12, 13-Ru/Os.
The dienyl and allylic forms of the tcne adducts could
be distinguished by their 31P NMR spectra, which
contained resonances at δ 40.74 (PPh3 in 11), 7.31 and
8.90 [J(PP) 80.7 Hz, dppm in 12], 65.32 and 80.09 [J(PP)
56.1 Hz, dppe in 13-Ru], and -9.95 and 38.64 [J(PP)
29.6 Hz, dppe in 14]). In the latter, the resonance at δ
-9.95 is assigned to the noncoordinated PPh2 group. In
addition, the conformation of the cyanocarbon ligands
in these complexes renders the two 31P nuclei in the
dppm or dppe ligands inequivalent, and the correspond-
ing resonances are found as AB quartets. In the case of
14, the opening of the Ru-P-C-C-P chelate ring
during the reaction is confirmed by the 31P NMR
spectrum, which contains two pseudodoublets (an AB
quartet) at δ -10.0 and 38.7, and the X-ray structure
(below).
The IR spectra contained one (11) or two (12, 13-Ru/
Os, 14) ν(CN) bands at ca. 2200 cm-1, and the 1H
spectra contain the resonances expected from the vari-
ous Cp, substituted C5H4, and phosphine ligands. In the
13C NMR spectra of 11-14 (Tables 1 and 2), the C5H4
ring carbons appear as four signals between δ 65 and
76 as a result of the asymmetry of the cyanocarbon
substituent. The Cipso resonances move downfield from
the alkynyl precursors to δ ca. 84-87 for the η1-dienyl
compounds and to δ ca. 91-92 for the allylic systems.
Fe-Cp, Ru-Cp, and Os-Cp singlets occur at δ ca. 70-
72, 84-87, and 84, respectively, while the Cp* ligand
in 14 gives rise to signals at δ 8.35 (Me) and 98.2 (ring
C). Resonances for the CN groups appear in the region
δC 111-120, some resonances showing a doublet cou-
pling to phosphorus and tentatively assigned to the CN
(15) Henderson, W.; McIndoe, J. S.; Nicholson, B. K.; Dyson, P. J.
J. Chem. Soc., Dalton Trans. 1998, 519.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5245
Scheme 5
Figure 1. Projection of a molecule of Ru(CtCFc)(dppe)-
Cp (3-Ru).
15, they are on opposite faces. As remarked upon earlier,
the Ru-C(2) separation is short [1.981(7) Å], suggesting
a degree of multiple-bond character, which can be
interpreted as giving some carbenic character to this
carbon atom.
Addition of electron-deficient alkenes such as tcne to
alkynyl-transition metal compounds proceeds via a
short-lived radical species (which was not observed in
the reactions described on this occasion) to give initially
a cyclobutenyl complex, which undergoes ring-opening
to form the butadienyl derivative (Scheme 3).12 Similar
reactions have been reported recently for HCtCFc,
FcCtCFc, and FcCtCCtCFc.14 If the metal center
contains easily displaceable ligands, further attachment
of the dienyl ligand by formation of a η3-ligand with
concomitant loss of a two-electron donor ligand may
then occur. Here, we find the reaction stopping at the
dienyl stage for 12, 13-Ru, and 13-Os, which contain
chelating dppm or dppe ligands, but proceeding to the
η3-dienyl for 11 (containing monodentate PPh3) and,
surprisingly, also for 14, in which the original η2-dppe
ligand becomes monodentate. No doubt this is the result
of the increased steric hindrance of Cp* compared with
Cp.
Another common reaction of alkynyl groups attached
to electron-rich transition metal centers is the addition
of cationic electrophiles, such as the proton or Me+, to
give the corresponding vinylidenes.16 Reactions between
5, 6, and 7 and MeI were carried out in thf in the
presence of Na[BPh4] to give dark red [1,1′-{Cp′(PP)-
Ru(dCdCMe)}2Fc′][BPh4]2 [Cp′ ) Cp, PP ) (PPh3)2
(17), dppe (18); Cp′ ) Cp*, PP ) dppe (19)] (Scheme 5).
These derivatives were readily identified by the large
downfield shifts found for the RudCdC carbons at δ
ca. 350-355, showing a triplet J(CP) of ca. 17 Hz,
characteristic of a vinylidene carbon. Other resonances
were as expected, with Câ at δ ca. 120 and the Me
signals at δ 9-12. The IR spectrum contains ν(CC)
bands at 1650 and 1579 cm-1. The ES mass spectra
contained ions assigned to the parent dications.
Figure 2. Projection of a molecule of 1,1′-{Cp(dppe)RuCt
C}2Fc′ (6).
Molecular Structures. The structures of the alkynyl
complexes 1-4, 6, 7, and 8 have been determined by
crystallographic methods. Plots of molecules of 3-Ru
and 6, which are representative, are given in Figures 1
and 2, and selected bond distances and angles from the
entire series are collected in Table 3. Geometries of the
M(PP)Cp′ fragments are similar to those of many
previously reported examples, the structural determina-
tions of 7 and 8 allowing comparison of the appropriate
parameters that involve the metal atoms, the iron being
included in square brackets. The Ru-P distances range
between 2.246(4) and 2.2864(7) Å [2.179, 2.185(3) Å],
the average Ru-C(Cp) distances fall between 2.23 and
2.25 Å [2.13 Å], and Fe-C5 ring distances within the
ferrocenyl moieties range between 2.03 and 2.05 Å [2.06
Å]. All complexes have pseudo-octahedral geometries
about the metal centers, with P(1)-M-P(2) angles
reflecting the bite angles of the tertiary phosphines, e.g.,
PPh3, 100.97°, 83.96(11)°, dppm, 71.30(3)°, dppe ca. 83°
[85.86(9)° for Fe]. Angles P(1,2)-Ru-C(1) range be-
tween 80.6° and 90.7(4)°, there being surprisingly little
difference between those in 7 and 8 [range 84.0-86.7-
(3)°]. The disubstituted ferrocenes are centrosymmetric
and isostructural.
Distances involving the alkynyl ligands are also
within previously observed ranges, e.g., M-C(1) be-
tween 2.00(1) and 2.023(1) Å [1.913(9) Å for Fe], C(1)-
C(2) 1.206(4)-1.25(2) Å [1.23(1) Å for 8], and C(2)-
(16) (a) Bruce, M. I.; Swincer, A. G. Adv. Organomet. Chem. 1983,
22, 59. (b) Bruce, M. I. Chem. Rev. 1991, 91, 197.

5246 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
Figure 3. Projection of a molecule of Ru{C[dC(CN)2]CFcd
C(CN)2}(dppe)Cp (13-Ru).
Figure 4. Projection of a molecule of Fc′[{η3-C[C(CN)2]Cd
C(CN)2}Ru(PPh3)Cp]2 (16).
C(201) 1.425(5)-1.45(1) Å. Of some interest is the Fe-
C(201) ring-metal distance, which is often the longest
of the 10 C(ring)-Fe distances in each molecule, prob-
ably because of weakening of the ring-Fe bond as a
result of electron removal by the substituent. As antici-
pated, the Ru-C(1)-C(2)-C(201) arrays are essentially
linear, the maximum deviation being found at C(2) in
2 [171.3(3)°]. However, as others have pointed out in a
recent extensive survey,17 factors involving bending at
the carbon atoms of alkyne and poly-yne chains are not
well understood, most discussions concluding that crystal-
packing effects resulting from low bending modes at the
chain carbons are the most likely cause.
The tcne adducts 11, 13-Ru, 13-Os, 14, 16, and 19
were also crystallographically characterized, and rep-
resentative molecular plots of 13-Ru, 16, and 19 are
shown in Figures 3-5, with selected bond parameters
given in Table 4. In 13-Ru/Os, the σ-dienyl structure
of the cyanocarbon ligand is confirmed, with Ru-C(2)
2.086(2) Å. Here, the Ru-P(1,2) separations [2.3328,
2.3054(6) Å] are somewhat longer than those found in
the parent alkynyls, probably because the back-bonding
into the tertiary phosphine is reduced as a result of the
strongly electron-withdrawing nature of the cyanocar-
(17) Szafert, S.; Gladysz, J. A. Chem. Rev. 2003, 103, 4175.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5247
when compared with the precursor 7. Other parameters
are similar to those found in related complexes, such
as [Ru(dCdCMePh)(PPh3)2Cp]I.19
Ruthenium-Osmium Pairs. The structure deter-
minations for the ruthenium/osmium pairs 1-Ru/Os and
13-Ru/Os allow a comparison of structural parameters
involving the two metals. The two sets of complexes are
each isomorphous, with differences in unit cell volume
only 6 (1) or -14 Å3 (13). As expected from previous
results, bond lengths (Å) involving the two metals are
essentially identical: M-P 2.286(1)/2.287(1) for 1, 2.3054,
2.3328(6)/2.2978(9), 2.3278(9) for 13; M-C(Cp) (av)
2.234(16)/2.233(16) for 1, 2.245(6)/2.255(7) for 13, M-C(1)
2.017(3)/2.026(4) for 1; M-C(2) 2.086(2)/2.065(3) for 13.
Electrochemistry. The electrochemical responses of
complexes 1-Ru, 3-Ru, and 4, together with the corre-
sponding trimetallic complexes [5]PF6, 6, and 7, were
examined by cyclic voltammetry. All potentials were
referenced against internal ferrocene/ferrocinium or
colbatocene/cobaltocenium standards and converted to
the saturated calomel electrode (SCE) scale.20 At a scan
rate v g 100 mV s-1, each complex displayed two
chemically reversible oxidation processes at moderate
potentials, which were separated by 530-690 mV (Table
5). The equal current ratios and peak areas, and hence
number of electrons transferred during each oxidation
event, indicate each wave to be associated with a one-
electron redox process. In the case of the trimetallic
species this clearly points to substantial interactions
between the metal centers, which decouple the oxidation
potentials of the otherwise identical ruthenium centers.
A third oxidation process could also be detected nearer
the electrochemical limit of the solvent window. How-
ever, the trications generated as a consequence of this
third oxidation event were chemically unstable on the
time scale of the voltammetry experiment, as evidenced
by the observation of a large number of product waves
in the reverse cathodic sweep.
It is interesting to note that the first oxidation of the
bimetallic complexes (Table 5) occurs at significantly
less positive potentials than those of the monometallic
models Ru(CtCPh)(PPh3)2Cp (0.535 V), Ru(CtCPh)-
(dppe)Cp* (0.245 V), or ferrocene (0.46 V) collected
under identical conditions,21 probably as a result of the
electron-withdrawing effect of the Ph groups. The first
oxidation of the trimetallic complexes 5 and 6 was
shifted by ca. -170 mV relative to the first oxidation of
1-Ru and 3-Ru; the second oxidation processes of the
trimetallic complexes were shifted by ca. -230 mV
relative to the appropriate bimetallic analogues. Curi-
ously, the first and second oxidation potentials of the
Ru(dppe)Cp* derivative 7 are similar to those of 4.
Nevertheless the large separation of the redox potentials
in both the bi- and trimetallic complexes indicates the
high thermodynamic stabilities of the monocations with
respect to disproportionation, and large values of the
comproportionation constant KC (108-1011) in each case.
No doubt this is a function of the differences in the redox
centers involved in these events.
Figure 5. Projection of the cation in [Fc′{CMedCd[Ru-
(dppe)Cp*]}2](BPh4)2 (19).
bon ligand. Within the latter, the distinction between
C-C single [C(1)-C(2) 1.491(3)/1.495(5) Å; values for
Ru/Os] and CdC double bonds [C(1)-C(110) 1.380(3)/
1.390(5) Å; C(2)-C(210) 1.362(3)/1.372(5) Å] is clear,
with the Fc substituent linked by C(301)-C(3) [1.461-
(3)/1.459(5) Å].
The so-called allylic complexes Ru{η3-C(CN)2CFcCd
C(CN)2}(P)Cp (P ) PPh3 11, dppe-P 14) and the disub-
stituted derivative Fc′[{η3-C[C(CN)2]CdC(CN)2}Ru-
(PPh3)Cp]2, 16, contain the cyanocarbon ligand acting
as a three-electron donor to the ruthenium center.
Examples of this type of complex have been reported
before, there being some discussion as to the nature of
the bonding of this ligand. The short Ru-C(2) distances
[1.978-1.982(3) Å] are consistent with a degree of
multiple bonding, which is also reflected in the 13C
chemical shifts of these carbons (δ ca. 180). The separa-
tions Ru-C(3) and Ru-C(4) are between 2.123 and
2.171(3) and 2.199 and 2.217(3) Å, respectively, which
are consistent with an olefinic η2 interaction. The C(2)-
C(3) and C(3)-C(4) separations suggest a degree of
delocalization, although the C(1)-C(2) separations are
short [1.34-1.363(4) Å] and are also consistent with a
CdC double bond. The best interpretation is probably
as a chelating vinyl carbene, as found earlier.12
Of interest in the structure of 14 is the partial
occupancy of an oxygen atom attached to P(2) [P(2)-
O(2) 1.24(1) Å, C(02)-P(2)-O(2) 118.8(6)°] and sup-
ported by the presence of a second resonance in the 31
P
NMR spectrum. It is likely that during workup partial
oxidation of the free P(2) atom in 14 occurred. On an
earlier occasion, we described the formation of a mono-
dentate dppe complex, accompanied by the analogous
dppeO derivative, although in that instance, separation
and full characterization of the two compounds was
possible.18
The bis-vinylidene complex 19 is centrosymmetric,
and the structure confirms the site of addition of the
Me group. The Ru-P distances [2.298, 2.319(1) Å] are
longer than those found in neutral complexes, as a
result of removal of charge to the positive center. The
Ru-C(1) [1.859(4) Å] and the C(1)-C(2) distances
[1.331(6) Å] confirm the vinylidene formulation, with
considerable shortening and lengthening, respectively,
(19) Bruce, M. I.; Humphrey, M. G.; Snow, M. R.; Tiekink, E. R. T.
J. Organomet. Chem. 1986, 314, 213. For a summary of other Ru/Os-
vinylidene structures, see: Puerta, M. C.; Valerga, P. Coord. Chem.
Rev. 1999, 193-195, 977.
(20) Pavlishchuk, V. V.; Addison, A. W. Inorg. Chim. Acta 2000, 298,
97.
(21) Roberts, R. L.; Hartl, F.; Low, P. J. Unpublished work.
(18) Bruce, M. I.; Skelton, B. W.; White, A. H.; Zaitseva, N. N. J.
Organomet. Chem. 2002, 650, 141.

5248 Organometallics, Vol. 24, No. 22, 2005
Table 4. Bond Distances and Angles for 11, 13-Ru/Os, 14, 16, and 19
Bruce et al.
11
13-Ru
13-Osa
14
16
19b
Bond Distances (Å)
2.3278(9)
Ru-P(1)
Ru-P(2)
Ru-C(cp)c
(av)
2.3883(6)
2.3328(6)
2.3054(6)
2.247-2.261(2)
2.254(6)
2.028-2.048(2)
2.034-2.058(3)
2.043(8)
2.044(9)
1.904
1.650, 1.646
2.048(2)
2.086(2)
2.4061(9)
2.384(2)
2.319(1)
2.2978(9)
2.298(1)
2.209-2.264(2)
2.235(21)
2.026-2.045(3)
2.039-2.049(3)
2.036(7)
2.045(4)
1.884
2.241-2.273(4)
2.255(7)
2.017-2.047(4)
2.022-2.058(5)
2.033(14)
2.044(15)
1.899
1.644, 1.647
2.047(4)
2.065(3)
2.199-2.319(3)
2.26(5)
2.167-2.263(8)
2.21(4)
2.012-2.062(9)
[2.012-2.062(9)]
2.041(19)
[2.041(19)]
1.866
2.265-2.327(4)
2.291(23)
2.046-2.080(5)
[2.046-2.080(5)]
2.055(14)
[2.055(14)]
1.939
1.667 [1.667]
2.080(5)
Fe-C(cp)
2.028-2.054(4)
2.029-2.052(4)
2.046(11)
2.044(9)
unprimed (av)
primed (av)
Ru-C(10)
Fe-C(30, 30′)
Fe-C(301)
Ru-C(2)
1.900
1.635, 1.643
2.037(2)
1.652, 1.653
2.050(3)
1.653 [1.653]
2.050(8)
1.982(2)
1.978(3)
1.981(3)
Ru-C(3)
Ru-C(4)
2.137(2)
2.171(3)
2.123(8)
2.199(2)
2.217(3)
2.201(8)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(3)-C(301)
C-CN
1.351(3)
1.380(3)
1.491(3)
1.362(3)
1.461(3)
1.438-1.443(3)
1.439
1.396(5)
1.495(5)
1.372(5)
1.459(5)
1.417-1.433(6)
1.428
1.363(4)
1.34(1)
1.439(3)
1.431(5)
1.43(1)
1.518(7)
1.331(6)
1.476(3)
1.477(4)
1.47(1)
1.473(3)
1.468(4)
1.47(1)
1.439-1.453(3)
1.445
1.433-1.458(5)
1.447
1.43-1.46(1)
1.44
(av)
Bond Angles (deg)
82.25(3)
P(1)-Ru-P(2)
P(1)-Ru-C(2)
P(1)-Ru-C(3)
P(1)-Ru-C(4)
P(1)-Ru-C(10)
P(2)-Ru-C(2)
P(2)-Ru-C(10)
C(2)-Ru-C(4)
C(2)-Ru-C(10)
C(3)-Ru-C(10)
C(4)-Ru-C(10)
C(30)-Fe-C(30′)
Ru-C(2)-C(1)
Ru-C(2)-C(3)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(2)-C(3)-C(301)
C(4)-C(3)-C(301)
82.56(2)
97.49(5)
82.11(4)
94.84(6)
117.46(6)
95.63(6)
118.4
97.65(9)
91.26(9)
112.15(8)
91.79(8)
120.2
95.6(2)
119.2(2)
97.9(2)
116.4
125.8
99.59(6)
124.2
125.8
99.66(9)
125.0
127.2
134.3
70.19(8)
131.6
69.7(1)
133.4
70.3(3)
133.0
118.9
118.2
124.1
127.6
124.5
132.8
134.7
131.6
177.5
176.7
177.0
178.1
178.5
180
145.3(2)
75.4(1)
137.9(2)
111.6(2)
122.7(2)
124.6(2)
123.9(2)
122.4(1)
112.8(2)
119.3(2)
116.9(2)
123.8(2)
124.9(3)
122.6(2)
111.6(3)
119.1(3)
117.4(3)
123.5(3)
144.1(3)
77.3(2)
137.1(3)
111.6(3)
123.8(3)
124.6(3)
140.7(6)
75.1(4)
141.2(8)
112.4(7)
122.4(7)
124.9(7)
a For Ru, read Os. b For 19 read C(20), C(20′), C(201) for C(30), C(30′), C(301): Ru-C(1) 1.859(4), C(2)-C(201) 1.475(7) Å; P(1, 2)-
Ru-C(1) 93.9, 81.9(1), C(1)-Ru-C(10) 123.0, Ru-C(1)-C(2) 177.7(4), C(1)-C(2)-C(201) 123.9(4), C(1)-C(2)-C(3) 119.0(4), C(3)-C(2)-
C(201) 117.0(4)°. c C(n0) are the Cp centroids.
It was of interest to explore the nature of the interac-
tions occurring between the metal centers in these
linear heterobimetallic complexes. The electronic (UV-
vis-NIR) and vibrational (IR) spectra of the chemically
stable, redox-accessible oxidation states of 1-Ru, 3-Ru,
and 4-7 were obtained using spectro-electrochemical
methods. Although each complex in this series gave rise
to two redox events that were chemically reversible at
room temperature on the time scale of the cyclic
voltammetric experiment, the dicationic species proved
to be less robust on the longer time scale required for
the electrolyses in the spectro-electrochemical cells.
Others have commented upon the chemical instability
of similar species on previous occasions.8 Infrared
spectra were therefore collected at -20 °C, using a low-
Table 5. Electrochemistry of Some
Ferrocenylethynyl-Metal Complexes 1-19a
compound E1/V
E2/V
+0.13 +0.82
+0.05 +0.69
∆E/mV
KC
E3/V
1-Rub
1-Os
2
690
640
560
580
630
620
530
640
180
690
660
3.5 × 1011
6.7 × 1010 +1.40 (irrev)
3.0 × 109 +1.40 (irrev)
8.0 × 109
+0.13 +0.69
+0.14 +0.72
+0.05 +0.68
-0.04 +0.58
-0.03 +0.50
0.04 +0.68
-0.31 -0.13
+0.08 +0.77
+0.09 +0.75
-1.05 +0.72
-1.50 +0.74
-1.47 +0.74
-1.43 +0.67
-1.25 -1.03
+0.48 +0.92 (irrev)
-1.65 -1.56
+0.44 +0.89 (irrev)
3-Rub
4b
4.6 × 1010 +1.21 (irrev)
2.9 × 1010 +0.93 (irrev)
9.5 × 108 +0.81 (irrev)
4.3 × 1010 +1.29 (irrev)
1.1 × 103 +0.64
4.7 × 1011 +1.65 (irrev)
1.5 × 1011
[5]+c
6
7
8
9
10
11
12
13
14
16
17
18
19
+1.79
+1.11
+1.15
+1.67 (irrev)
22
volume cell of standard design to minimize the time
+0.93
necessary for the experiment, and hence the opportunity
for the dications to degrade. The chemical reversibility
of each electrogenerated species was established by the
recovery of the spectrum associated with the preceding
oxidation state following back-reduction of the sample
solution.
+0.89 (irrev)d
a All electrochemical experiments were performed in 0.1 M
[NBu4]PF6 in CH2Cl2, referenced to FeCp2/[FeCp2]+ ) 0.46 V or
CoCp2/[CoCp2]+ ) -0.87 V. b Electrochemistry on literature com-
pounds, comparative values in ref 8a. c As compound 5 was not
soluble enough for electrochemical studies, these values were
obtained from [5]PF6. d A second irreversible oxidation wave was
observed at +1.15 V.
(22) (a) Hartl, F.; Luyten, H.; Nieuwenhuis, H. A.; Schoemaker, G.
C. Appl. Spectrosc. 1994, 48, 1522. (b) Mahabiersing, T.; Luyten, H.;
Nieuwendam, R.; Hartl, F. Collect. Czech. Chem. Commun. 2003, 68,
1687.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5249
Figure 6. Spectroelectrochemically generated IR spectra of (a) [1-Ru]n+ (n ) 0, 1), (b) [1-Ru]n+ (n ) 1, 2), (c) [5]n+ (n )
0, 1), and (d) [5]n+ (n ) 1, 2).
Table 6. Infrared ν(CC) Absorptions of
Ferrocenylethynyl-Metal Complexes 1-Ru, 3-Ru,
and 4-7 in the Oxidation States 0, +1, and +2
(CH2Cl2/0.1 M NBu4PF6 Solutions)
therefore likely that the second oxidation event is
ferrocene-localized.
The UV-vis-NIR spectra of 1-Ru, 4, 5, and 7 and
their one-electron-oxidized products were collected in an
optically transparent electrode (OTE) cell (Table 7).23
The chemically robust neutral and mono-oxidized spe-
cies could be generated and observed without difficulty
at room temperature. However, in spite of the well-
behaved CV and IR spectroelectrochemical response, the
time required for electrogeneration in the larger volume
OTE cell, and possible intrusion of atmospheric mois-
ture, resulted in decomposition of the dioxidized species
before reliable spectra could be collected. Cooling the
sample to -30 °C did not alleviate the problem.
The electronic absorption spectrum of 1-Ru was
characterized by two bands in the UV region, which tail
into a broad ferrocene d-d band near 450 nm/22 000
cm-1 (Table 7). The introduction of a second ruthenium
acetylide fragment in 5 (electrogenerated in the OTE
cell from the soluble sample of [5]PF6]) had little effect
on this generalized profile, except for an increase in the
intensity of the UV bands relative to the d-d band. One-
electron oxidation of 1-Ru results in subtle shifts in the
highest energy bands, accompanied by the appearance
of two new bands in the visible region which do not
display vibrational fine structure. Similar visible bands
are often associated with oxidized (17-e) products de-
rived from group 8 metal alkynyl complexes and are
usually attributed to transitions from the occupied
orbitals to the stabilized unoccupied orbital set. The
delocalized nature of the frontier orbitals can make
assignments of such bands difficult, but given the
considerable acetylide (π*) character of the LUMO,24 an
MLCT description is a reasonable approximation. In
addition, at least two overlapping transitions are clearly
ν(CC)/cm-1
neutral
+1
+2
1-Ru
2080
2082
2080
2075
2080
2076
1990
1990
1984
1986, 2039(sh)
1991, 2043(sh)
1981, 2037
1990
1990
1984
1986, 2039(sh)
1991, 2043(sh)
1981, 2037
3-Ru
4
5
6
7
In CH2Cl2 solution containing 0.1 M [NBu4]PF6 as
supporting electrolyte, each complex in the series 1-Ru,
3-Ru, 4-7 was characterized by a single, weak ν(CtC)
band at ca. 2080 cm-1. Oxidation of 1-Ru, 3-Ru, and 4
to the corresponding monocations resulted in a consis-
tent shift of the ν(CtC) bands to lower energy (∆ν ≈
90-100 cm-1) (Figure 6, Table 6). The lowering of the
ν(CtC) frequency that occurs upon oxidation may be
compared with the corresponding differences in [Ru(Ct
CPh)(L2)Cp′]n+ (n ) 0, 1; ∆ν ≈ 150 cm-1).21 We also note
that the absolute values are similar to those of related
homometallic iron systems for which delocalized elec-
tronic structures have been proposed.8b The spectra of
the trimetallic species 5+, 6+, and 7+ each exhibited a
similarly intense ν(CtC) band at almost the same
energy as the corresponding bimetallic species, in ad-
dition to a weak band (or shoulder) near 2040 cm-1
(Table 6). In contrast, the second oxidation of the bi- or
trimetallic species did not result in a decrease in the
ν(CtC) frequency, but rather in a partial decrease in
the intensity of the bands (Figure 6, Table 6). Clearly,
while the first oxidation process involves orbitals with
some CtC character, the second must involve an orbital
that does not interact with the acetylene moiety. It is
(23) Duff, C. M.; Heath, G. A. Inorg. Chem. 1991, 30, 2528.

5250 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
Table 7. Electronic Absorption Spectra of Ferrocenylethynyl-Metal Complexes 1-Ru, 4, 5, and 7 in the
Oxidation States 0 and +1
complex
band maxima/cm-1 (ꢀ/dm3 mol-1 cm-1
)
Neutrals
1-Ru
35 000 (17400)
37 600 (22600)
28 700 (8550)
∼23 000 (2220)
4
5
7
28 500 (9580)
37 900 (26800)
25 800 (14700)
∼22 000 (2190)
Monocations
[1-Ru]+
[4]+
33 200 (17582)
37 700 (21 589)
33 800 (33 416)
38 610 (26 791)
23 500 (4656)
30 900 (11 895)
25 100 (8858)
32 800 (18 711)
17 000 (13270)
16 100 (6906)
16 400 (15 900)
16 300 (8997)
6520 (6425)
∼6470a
4760 (49560)
∼5130 (4430)
4740 (4130)
4590 (4270)
[5]+
7360 (5740)
6540 (4100)
[7]+
a Unresolved.
observed in the NIR region of 1-Ru. By analogy with
Hush-style descriptions of the spectra of mixed valence
complexes, these bands are likely due to transitions
from lower-lying occupied orbitals to the SOMO.
tentatively attributed to reversible events at the fer-
rocene and ruthenium centers. In addition, reversible
processes in the region -1.05 to -1.47 V are assigned
to reductions of the dicyanomethylene groups on the
basis of the well-known ready reduction of tcne to the
anion radical and dianion and the proclivity of the
cyano-alkene and similar dicyanomethylene compounds
to behave as electron acceptors in the formation of
molecular complexes with electron-rich systems.25 Of
interest in the CV of the dicationic bis(vinylidene)
complex 18 is the presence of two cathodic waves at
-1.56 and -1.65 V, assigned to consecutive reduction
of the dication and cation, and partially chemically
reversible processes at +0.89 and +1.15 V, which we
are inclined to assign to oxidation of the ferrocene and
ruthenium centers, respectively.
Mo1ssbauer Spectroscopy. The availability of chemi-
cally isolable samples of both 5 and [5]PF6 permitted
us to investigate the site of oxidation in this complex in
more detail using Mo¨ssbauer spectroscopy. The spec-
trum of 5 was recorded at 80 K and contained a unique
doublet [IS ) 0.539(3) mm s-1 vs Fe; QS ) 2.357(6) mm
s-1] very similar to that of ferrocene itself [90 K: IS
0.531(3) mm s-1; QS 2.419(1) mm s-1].26 Under similar
conditions, the Mo¨ssbauer spectrum of [5]PF6 shows a
doublet [IS ) 0.548(3) mm s-1 vs Fe; QS ) 0.952(3) mm
s-1], which is accompanied by a small doublet with
parameters identical with those of 5, indicating the
presence of ca. 10% of the neutral complex in the
sample. The observation of a doublet associated with
[5]PF6 is not in keeping with the classic Mo¨ssbauer
spectra of ferrocenium derivatives, which are instead
characterized by an almost zero value of the quadrupole
splitting.27 The Mo¨ssbauer spectrum of [5]PF6 further
supports the concept of a delocalized structure, rather
than an oxidation event localized on either the Ru or
Fe centers. If one considers complexes [5]+, [6]+, and
[7]+ as being derived from the 35-e butadiyndiyl com-
plexes [{Ru(PP)Cp′}2(µ-CCCC)]+,6 it appears that the
introduction of a 1,1′-ferrocenyl moiety within the C4
bridging ligand hinders delocalization of the unpaired
The spectrum of [5]+ displays the same characteristic
transitions as observed in the bimetallic analogue 1-Ru,
and it is interesting to note that the lowest energy NIR
band is at the same energy in both systems. The
availability of samples of [5]PF6 allowed us to record
the UV-vis-NIR spectrum of this material in solvents
of different dielectric strength free from complications
arising from the supporting electrolyte necessary for
spectro-electrochemical work. The transitions in [5]+
were found to be independent of the solvent environ-
ment, which suggests that this monocation is best
described with a delocalized electronic structure. The
spectra of the more electron-rich complexes [4]+ and [7]+
were essentially identical to those of their Ru(PPh3)2-
Cp analogues, although the NIR transitions in [4]+ were
not well resolved (Table 7).
The IR and electronic spectra of the mono-oxidized
systems are consistent with an interpretation of the
electronic structure, which involves significant delocal-
ization of the odd electron between the ferrocene center
and one of the half-sandwich ruthenium centers. The
observation of a second ν(CtC) band in the IR spectra
of the trimetallic cations [5]+, [6]+, and [7]+, which is
not observed in the bimetallic analogues [1-Ru]+, [3]+,
and [4]+, together with the similar electronic absorption
spectra of the bi- and trimetallic complexes, suggest that
electron exchange between the Ru centers through the
Fc center does not occur (i.e., there is no evidence of a
new band in the trimetallic species that can be assigned
to a photoinduced Ru(II)fRu(III) MMCT process). The
less intense higher-lying shoulder would then be as-
signed to the largely nonoxidized Ru(CtC)Cp moiety
in the trinuclear cation, which is shifted relative to the
neutral precursor by the electron-withdrawing nature
of the oxidized fragment. This interpretation is also
consistent with the observation of well-separated one-
electron anodic waves by cyclic voltammetry.
The second oxidation event, which does not influence
the ν(CtC) frequency, is consistent with a ferrocene-
based oxidation process, but unfortunately we have not
yet been able to access the two-electron-oxidized com-
plexes either chemically or electrochemically for elec-
tronic spectroscopic work.
There are significant waves in the CVs of the cyano-
carbon-containing complexes between +0.67 and +0.75
V, and between +0.93 and +1.79 V, which are are
(24) (a) McGrady, J. E.; Lovell, T.; Stranger, R.; Humphrey, M. G.
Organometallics 1997, 16, 4004. (b) Koentjoro, O. F.; Rousseau R.; Low,
P. J. Organometallics 2001, 20, 4502.
(25) (a) Webster, O. W.; Maher, W.; Benson, R. E. J. Am. Chem.
Soc. 1962, 84, 3678. (b) Ciganek, E.; Linn, W. J.; Webster O. W. In
Chemistry of the Cyano Group; Patai, S., Ed.; Wiley: New York, 1980;
Chapter 9, p 423.
(26) Basta, R.; Wilson, D. R.; Ma, H.; Arif, A. M.; Herber, R. H.;
Ernst, R. D. J. Organomet. Chem. 2001, 637-639, 172.
(27) (a) Collins, R. L. J. Chem. Phys. 1965, 42, 1072. (b) Nlate, S.;
Ruiz, J.; Sartor, V.; Navarro, R.; Blais, J.-C.; Astruc, D. Chem. Eur. J.
2000, 6, 2544.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5251
FeCl(dppe)Cp*,29 RuCl(dppe)Cp,30 RuCl(dppe)Cp*,8b OsCl-
(PPh3)2Cp,31 FcCtCH,9 and 1,1′-(SiMe3CtC)2Fc′9 were pre-
pared using the cited methods.
electron between the two ruthenium centers. Again it
is unfortunate that the instability precluded a Mo¨ss-
bauer investigation of the two-electron-oxidized forms
of these materials.
(a) Ru(CtCFc)(PPh3)2Cp (1-Ru). A modified literature
procedure was employed. RuCl(PPh3)2Cp (160 mg, 0.22 mmol),
FcCtCH (78 mg, 0.371 mmol), and Na[BPh4] (112 mg, 0.318
mmol) were heated in methanol (10 mL) for 1 h at 50 °C. The
vessel was cooled in ice, an excess of methanolic sodium
methoxide was added, and the mixture was stirred for 15 min.
The yellow precipitate that formed was collected on a sinter
and washed with methanol and hexane to afford Ru(CtCFc)-
(PPh3)2Cp (1) (140 mg, 71%). Crystals were obtained from
benzene-hexane and identified by comparison with the
literature.8a 1H NMR: δ 4.09, 4.52 (2 × m, 2 × 2H, C5H4 of
Fc), 4.10 (s, 5H, CpFe), 4.41 (s, 5H, CpRu), 6.97, 7.73 (2 × m,
18 + 12H, Ph). 31P NMR: δ 51.87.
Conclusions
We have described the preparation of several com-
plexes containing electron-rich M(PP)Cp′ (M ) Fe, Ru,
Os) groups attached to a ferrocene nucleus via one or
two CtC triple bonds. Further reactions with the
electrophilic alkene tcne have produced either η1- or η3-
tetracyanobutadienyl complexes. Crystallographic char-
acterization of the majority of these compounds is
described. These compounds were prepared as part of
an investigation on the transmission of electronic effects
between transition metal end-caps on poly-yndiyl chains
containing other redox-active groups interrupting the
chain. The combined evidence from UV-vis-NIR and
IR spectroelectrochemistry and Mo¨ssbauer spectroscopy
supports the conclusions that while strong interactions
may occur between one Ru(PP)Cp′ moiety and a ferro-
cenyl center through an ethyndiyl bridge, the ferrocene
group acts as an insulator when inserted into the four-
carbon chain of the archetypal molecular wires {Ru(PP)-
Cp′}2(µ-CtCCtC).
(b) Os(CtCFc)(PPh3)2Cp (1-Os). Similarly, OsCl(PPh3)2-
Cp (107 mg, 0.131 mmol), HCtCFc (60 mg, 0.286 mmol), and
Na[BPh4] (111 mg, 0.324 mmol) were heated in refluxing
MeOH (10 mL) for 2 h to give Os(CtCFc)(PPh3)2Cp (1-Os) (95
mg, 73%). Anal. Calcd (C53H44FeOsP2): C, 64.37; H, 4.48; M,
989. Found: C, 64.30; H, 4.51. IR (Nujol): ν(CC) 2069s; other
bands at 1640m, 1585w cm-1. 1H NMR: δ 4.11 (br s, 7H, FeCp
+ C5H4), 4.41 (s, 5H, OsCp), 4.51 (m, 2H, C5H4), 6.95 (m, 18H,
Ph), 7.65 (m, 12H, Ph). 31P NMR: δ 2.93. ES-MS (positive ion,
m/z): 990, [M + H]+; 781, [M - HC2Fc]+; 728, [M - PPh3]+.
(c) Ru(CtCFc)(dppm)Cp (2). A mixture of RuCl(dppm)-
Cp (148 mg, 0.253 mmol), HCtCFc (59 mg, 0.281 mmol), and
Na[BPh4] (105 mg, 0.298 mmol) was heated in a refluxing
mixture of thf and NEt3 (1/1, 20 mL) for 16 h. After removal
of solvent, the residue was purified by column chromatography
(basic alumina, acetone-hexane, 9/1) to give Ru(CtCFc)-
(dppm)Cp (2) (105 mg, 55%) as a yellow solid. Crystals were
obtained from toluene. Anal. Calcd (C42H36FeP2Ru): 66.41; H,
4.78; M, 760. Found: C, 66.50; H, 4.82. IR (Nujol): 2087s,
Experimental Section
General Conditions. 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.
1586w, 1573w cm-1 1H NMR (d8-toluene): δ 3.75 (m, 2H,
.
Instrumentation. Infrared spectra were obtained on a
Bruker IFS28 FT-IR spectrometer. Nujol mull spectra were
obtained from samples mounted between NaCl disks. NMR
spectra were recorded on Varian 2000 instrument (1H at
300.13 MHz, 13C at 75.47 MHz, 31P at 121.503 MHz). Samples
were dissolved in C6D6, unless otherwise stated, contained in
5 mm sample tubes. Chemical shifts are given in ppm relative
to internal tetramethysilane for 1H and 13C NMR spectra and
external H3PO4 for 31P NMR spectra. Cyclic voltammograms
of complexes 1, 3, 4, [5]PF6, 6, and 7 were recorded with an
EG&G PAR Model 283 potentiostat. The CH2Cl2 solutions
contained 10-3 M complex and 0.1 M [NBu4]PF6 (Aldrich;
recrystallized twice from absolute EtOH and dried overnight
under vacuum at 80 °C) as supporting electrolyte. The solu-
tions were placed in an airtight single-compartment three-
electrode cell equipped with a Pt disk working electrode (0.42
mm2 apparent electrode surface, polished with a 0.25 µm
diamond paste), Pt gauze auxiliary electrode, and Ag wire
pseudo-reference electrode. In the case of 11-16, cyclic vol-
tammograms were recorded using an EG&G PAR Model 263
apparatus with a SCE reference electrode. In all cases,
C5H4), 3.80-3.81 (m, 7H, C5H4 + CpFe), 4.35-4.60 (m, 2H,
CH2), 4.85 (s, 5H, CpRu), 7.10-7.34 (m, 15H, Ph), 7.87-7.93
(m, 5H, Ph). 31P NMR (d8-toluene): δ 19.97 (dppm). ES-MS
(positive ion, MeOH + NaOMe, m/z): 783, [M + Na]+; 760,
M+; 551, [Ru(dppm)Cp]+.
(d) Ru(CtCFc)(dppe)Cp (3-Ru). As in (a) above, RuCl-
(dppe)Cp (140 mg, 0.233 mmol), FcCtCH (75 mg, 0.357 mmol),
and Na[BPh4] (136 mg, 0.386 mmol) were heated at 50 °C in
MeOH (15 mL) for 1 h to give Ru(CtCFc)(dppe)Cp (3-Ru) (147
mg, 82%). Orange crystals were obtained from CH2Cl2/MeOH
and identified by comparison with the literature report.8a 1H
NMR: δ 2.10-2.30, 2.60-2.80 (2 × m, 2 × 2H, dppe), 3.85,
3.93 (2 × m, 2 × 2H, C5H4 of Fc), 3.89 (s 5H, CpFe), 4.72 (s,
5H, CpRu), 6.98, 7.22-7.34, 8.06-8.12 (3 × m, 6 + 10 + 4H,
Ph). 31P NMR: δ 87.14.
(e) Os(CtCFc)(dppe)Cp (3-Os). A mixture of OsCl(dppe)-
Cp (62 mg, 0.093 mmol), HCtCFc (32 mg, 0.152 mmol), and
Na[BPh4] (57 mg, 0.167 mmol) was heated in refluxing MeOH
(10 mL) for 18 h. After cooling in ice, NaOMe [from Na (5 mg)
in MeOH (2 mL)] was added dropwise and the mixture was
stirred for 15 min. After this time, solvent was removed under
vacuum and the residue was purified by column chromatog-
raphy (basic alumina, acetone-hexane, 1/9) to give Os(Ct
CFc)(dppe)Cp (3-Os) (61 mg, 78%) as an orange powder. IR
ferrocene or cobaltocence was used as internal calibrant [E1/2
-
(FeCp2/[FeCp2]+) ) +0.46 V vs SCE in CH2Cl2; E1/2(CoCp2/
[CoCp2]+ ) -0.87 V vs SCE in CH2Cl2]. The IR spectro-
electrochemical experiments at variable temperatures were
performed with a previously described OTTLE cell positioned
in the sample compartment of a Bio-Rad FTS-7 FT-IR spec-
trometer.22 The solutions were 5 × 10-3 M in analyte and 3 ×
10-1 M in the supporting electrolyte, [NBu4]PF6. The UV-vis-
NIR spectro-electrochemical measurements were conducted
using an OTE cell similar to that described previously,23 from
CH2Cl2 solutions containing 1 × 10-1 M [NBu4]BF4 as sup-
porting electrolyte. Elemental analyses were performed at the
Centre for Micro-analytical Services (CMAS), Belmont, Vic.
Reagents. Ferrocene, tetracyanoethene, and Na[BPh4] (Al-
drich) were used as received. The compounds RuCl(PPh3)2Cp,28
(Nujol): ν(CtC) 2078s cm-1 1H NMR: δ 2.23-2.29, 2.51-
.
2.62 (2 × m, 2 × 2H, dppe), 3.85 (br s, 7H, C5H4 + Fe-Cp),
3.90 (m, 2H, C5H4), 4,62 (s, 5H, Os-Cp), 6.97-8.11 (m, 20H,
Ph). 31P NMR: δ 47.24. ES MS (positive ion, MeOH, m/z): 864,
[M + H]+; 655, [Os(dppe)Cp]+.
(28) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg.
Synth. 1990, 28, 270.
(29) Roger, C.; Hamon, P.; Toupet, L.; Rabaaˆ, H.; Saillard, J.-Y.;
Hamon, J.-R.; Lapinte, C. Organometallics 1991, 10, 1045.
(30) Alonso, A. G.; Reventos, L. B. J. Organomet. Chem. 1998, 338,
249.

5252 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
(f) Ru(CtCFc)(dppe)Cp* (4). As in (a) above, RuCl(dppe)-
Cp* (169 mg, 0.245 mmol), HCtCFc (77 mg, 0.367 mmol), and
Na[BPh4] (102 mg, 0.29 mmol) were heated in refluxing MeOH
(15 mL) to give yellow Ru(CtCFc)(dppe)Cp* (4) (165 mg, 75%).
Crystals were obtained from acetone. 1H NMR: δ 1.66 (s, 15H,
Cp*), 1.80-2.05, 2.60-2.90 (2 × m, 2 × 2H, dppe), 3.98, 4.21
(2 × s, C5H4), 4.09 (s, 5H, CpFe), 7.07, 7.24-7.35, 7.94-8.00
(3 × m, 6 + 10 + 4H, Ph). 31P NMR: δ 82.14.
washed with MeOH, and dried. Further purification was
achieved by dissolving in benzene (50 mL), diluting the filtered
solution with hexane (50 mL), and storing in the freezer
overnight to afford 1,1′-{Cp*(dppe)RuCtC}2Fc′ (40 mg, 10%).
Removal of solvent from the filtrate afforded pure 1-(Me3SiCt
C)-1′-{Cp*(dppe)RuCtC}Fc′ (10) (120 mg, 46%) as an orange
solid. Anal. Calcd (C53H56FeP2RuSi): C, 67.72; H, 6.00; M, 940.
Found: C, 67.80; H, 5.97. IR (Nujol): ν(CtC) 2166w, 2145m,
1
2106w, 2076s cm-1. H NMR: δ 0.27 (s, 9H, SiMe3), 1.63 (s,
(g) 1,1′-{Cp(Ph3P)2RuCtC}2Fc′ (5). A mixture of RuCl-
(PPh3)2Cp (240 mg, 0.331 mmol), 1,1′-(SiMe3CtC)2Fc′ (56 mg,
0.148 mmol), and KF (40 mg, 0.69 mmol) was heated in
refluxing thf-MeOH (3/1, 40 mL) for 16 h. The mixture was
cooled to rt, and the resulting solution filtered and washed
with methanol, ether, and hexane to afford 1,1′-{Cp(Ph3P)2-
RuCtC}2Fc′ (5) (145 mg, 61%) as a light yellow solid. Anal.
Calcd (C96H78FeP4Ru2): C, 71.46; H, 4.87; M, 1614. Found: C,
71.54; H, 4.77. IR (Nujol): ν(CtC) 2101w, 2069s; other bands
15H, C5Me5), 1.85-2.10, 2.60-2.90 (2 × m, 2 × 2H, 2 × CH2),
3.91, 4.08, 4.22, 4.38 (4 × m, 4 × 2H, C5H4), 7.06-7.40, 7.93
(m, 20H, Ph). 31P NMR (d8-toluene): δ 81.90. ES-MS (m/z):
941, [M + H]+.
Oxidation of 1,1′-{Cp(Ph3P)2RuCtC}2Fc′ (5). [FeCp2]PF6
(33 mg, 0.10 mmol) was added to 1,1′-{Cp(Ph3P)2RuCtC}2Fc′
(161 mg, 0.10 mmol) in a mixture of CH2Cl2 (2 mL) and
benzene (15 mL), and the resulting blue solution was stirred
at rt for 16 h. After this time, the blue precipitate was collected
and washed with Et2O and hexane to afford [1,1′-{Cp(Ph3P)2-
RuCtC}2Fc′]PF6 ([5]PF6) as a dark blue solid (151 mg, 86%).
Anal. Calcd (C96H78F6FeP5Ru2): C, 65.57; H, 4.47; M (cation),
1614. Found: C, 65.59; H, 4.38. IR (Nujol): ν(CC) 1993s (br),
ν(PF) 841s cm-1. ES MS (MeOH, m/z): 1614, M+.
1
at 1654w (br), 1586w, 1573w cm-1. H NMR: δ 4.05 (t, J 1.8
Hz, 4H, C5H4), 4.45 (s, 10H, Cp), 4.58, (t, J 1.8 Hz, 4H, C5H4),
6.90-7.10 (m, 40H, Ph), 7.73-7.88 (m, 20H, Ph). 31P NMR: δ
52.08. ES-MS (m/z): 1614, M+.
(h) 1,1′-{Cp(dppe)RuCtC}2Fc′ (6). Similarly, from RuCl-
(dppe)Cp (128 mg, 0.213 mmol), 1,1′-(SiMe3CtC)2Fc′ (40 mg,
0.106 mmol), and KF (13 mg, 0.224 mmol) the complex 1,1′-
{Cp(dppe)RuCtC}2Fc′ (6) was obtained (74 mg, 51%) as a light
orange solid. Anal. Calcd (C76H66FeP4Ru2): C, 67.06; H, 4.89;
M, 1361. Found: C, 67.04; H, 4.90. IR (Nujol): ν(CtC) 2114w,
Reactions with Tetracyanoethene (tcne). (a) With Ru-
(CtCFc)(PPh3)2Cp. A mixture of Ru(CtCFc)(PPh3)2Cp (58
mg, 0.065 mmol) and tcne (11 mg, 0.086 mmol) was stirred in
benzene (10 mL) at rt for 24 h. After removal of solvent,
purification of the residue by preparative TLC (dichlo-
romethane) afforded Ru{η3-C(CN)2CFcCdC(CN)2}(PPh3)Cp
(11) (37 mg, 75%) as a maroon solid. Crystals were obtained
from CH2Cl2-hexane. Anal. Calcd (C41H29FeN4PRu): C, 64.32;
H, 3.82; N, 7.32; M, 766. Found: C, 64.25; H, 3.78; N, 7.25%.
IR (Nujol): ν(CN) 2208; other bands at 1609m, 1596m, 1587w,
2089s; other bands at 1660w (br), 1585w, 1572w cm-1 1H
.
NMR: δ 2.02-2.22, 2.60-2.88 (2 × m, 2 × 4H, CH2), 3.57,
3.85 (2 × m, 2 × 4H, C5H4), 4.72 (s, 10H, Cp), 6.90-7.02 (m,
12H, Ph), 7.15-7.34 (m, 20H, Ph), 8.05-8.10 (m, 8H, Ph). 31
P
NMR: δ 87.13. ES-MS (positive ion, m/z): 1362, [M + H]+,
98; 682, [M + 2H]2+, 100.
In addition 1-(Me3SiCtC)-1′-{Cp(dppe)RuCtC}Fc′ (9) (10
mg, 11%) was isolated from the filtrate and purified by column
chromatography (basic alumina, 15% acetone-hexane) as an
orange-colored solid. Anal. Calcd (C48H46FeP2RuSi): C, 66.28;
H, 5.33; M, 870. Found: C, 66.30; H, 5.21. IR (Nujol): ν(CtC)
1
1571w cm-1. H NMR (CDCl3): δ 4.50-4.57 (m, 8H, C5H4 +
CpFe), 5.39 (m, 1H, C5H4), 7.40-7.52 (m, 15H, Ph). 31P NMR
(CDCl3): δ 40.74. ES-MS (positive ion, MeOH + NaOMe,
m/z): 789, [M + Na]+; 766, M+.
(b) With Ru(CtCFc)(dppm)Cp. Similarly, a mixture of
Ru(CtCFc)(dppm)Cp (60 mg, 0.079 mmol) and tcne (13 mg,
0.10 mmol) in benzene (10 mL) afforded dark red-brown Ru-
{C[dC(CN)2]dCFcdC(CN)2}(dppm)Cp (12) (51 mg, 73%). Anal.
Calcd (C48H36FeN4P2Ru): C, 60.51; H, 3.94; N, 5.76; M, 888.
Found: C, 61.00; H, 3.72; N, 5.76. IR (Nujol): ν(CN) 2212m,
2146m, 2080s cm-1 1H NMR: δ 0.23 (s, 9H, SiMe3), 2.10-
.
2.30, 2.60-2.85 (2 × m, 2 × 2H, 2 × CH2), 3.60-3.61 (m, 2H,
C5H4), 3.96 (s, 8H, 2 × C5H4), 4.69 (s, 5H, RuCp), 6.96-6.98,
7.21-7.31, 8.03-8.08 (3 × m, 20H, Ph). 31P NMR: δ 87.21.
ES-MS (m/z): 870, M+.
(i) 1,1′-{Cp*(dppe)RuCtC}2Fc′ (7). Similarly, from RuCl-
(dppe)Cp* (293 mg, 0.425 mmol), 1,1′-(SiMe3CtC)2Fc′ (66 mg,
0.175 mmol), and KF (21 mg, 36 mmol) in MeOH (60 mL) 1,1′-
{Cp*(dppe)RuCtC}2Fc′ (7) (136 mg, 52%) was obtained as an
orange solid. Crystals were obtained from thf-2-propanol.
Anal. Calcd (C86H86FeP4Ru2): C, 68.79; H, 5.77; M, 1501.
Found: C, 68.81; H, 5.63. IR (Nujol): ν(CtC) 2107w, 2082s;
1
2199m; other band at 1511m cm-1. H NMR (CDCl3): δ 2.46,
3.05, 3.48, 3.89 (4 × m, 4 × 1H, C5H4), 4.22 (s, 5H, FeCp),
4.35-4.39 (m, 2H, CH2), 4.93-5.10 (m, 6H, CH2 + RuCp),
6.52-6.58, 6.92-6.97, 7.09-7.12, 7.35-7.50, 7.80 (5 × m, 20H,
Ph). 31P NMR (CDCl3): δ 8.90 (d, J 80.7), 7.31 (d, J 80.7). ES-
MS (positive ion, MeOH + NaOMe, m/z): 1799, [2M + Na]+;
911, [M + Na]+.
1
other bands at 1586w, 1572w cm-1. H NMR: δ 1.68 (s, 30H,
(c) With Ru(CtCFc)(dppe)Cp. To a stirred solution of Ru-
(CtCFc)(dppe)Cp (65 mg, 0.084 mmol) in dichloromethane (5
mL) was added tcne (11.5 mg, 0.09 mmol), resulting in a dark
red solution. Stirring was continued for 1 h, after which the
solvent was removed in vacuo. The residue was purified by
chromatography (5% acetone-dichloromethane, flash silica)
to give Ru{C[dC(CN)2]dCFcdC(CN)2}(dppe)Cp (13-Ru) (56
mg, 74%) as a dark red solid. Crystals were obtained from CH2-
Cl2-hexane. Anal. Calcd (C49H38FeN4P2Ru‚0.6CH2Cl2): C,
62.53; H, 4.15; N, 5.88; M, 902. Found: C, 62.44; H, 4.18; N,
5.59. IR (Nujol): ν(CN) 2214s, 2204s; also 1508 cm-1. 1H NMR
(CDCl3): δ 2.05-2.55 (m, 4H, 2 × CH2), 3.22, 4.03, 4.47, 4.50
(4 × m, 4 × 1H, C5H4), 4.15 (s, 5H, FeCp), 4.97 (s, 5H, RuCp),
6.48-6.54, 7.08-7.20, 7.34-7.40, 7.53-7.57, 7.75-7.81, 7.79-
7.95 (6 × m, 20H, Ph). 31P NMR (CDCl3): δ 65.32 (d, J 56.1
Hz), 80.09 (d, J 56.1 Hz). ES-MS (MeOH + NaOMe, m/z): 925,
[M + Na]+. Crystals were obtained from CH2Cl2-hexane.
Me), 1.85-2.02, 2.65-2.95 (2 × m, 2 × 4H, CH2), 4.00, 4.29 (2
× m, 2 × 4H, C5H4), 7.00-7.09 (m, 16H, Ph), 7.15-7.28 (m,
12H, Ph), 7.33-7.41 (m, 6H, Ph), 7.97-8.03 (m, 6H, Ph). 31P
NMR: δ 82.10. ES-MS (m/z): 1501, M+; 752, [M + 2H]2+
.
(j) 1,1′-{Cp*(dppe)FeCtC}2Fc′ (8). Similarly, from FeCl-
(dppe)Cp* (160 mg, 0.256 mmol), 1,1′-(SiMe3CtC)2Fc′ (43 mg,
0.114 mmol), and KF (19 mg, 0.328 mmol) in MeOH (50 mL)
1,1′-{Cp*(dppe)FeCtC}2Fc′ (8) was obtained (9 mg, 6%) as an
orange solid. Anal. Calcd (C86H86Fe3P4): C, 73.20; H, 6.14; M,
1411. Found: C, 73.21; H, 6.22. IR (Nujol): ν(CtC) 2066s cm-1
.
1H NMR: δ 1.53 (s, 30H, Me), 1.75-2.00, 2.60-2.90 (2 × m, 2
× 4H, CH2), 4.14, 4.37 (2 × m, 2 × 4H, C5H4), 6.80-7.60 (m,
32H, Ph), 8.00-8.12 (m, 8H, Ph). 31P NMR: δ 101.44. ES-MS
(m/z): 1411, M+; 706, [M + 2H]2+
.
(k) 1-(Me3SiCtC)-1′-{Cp*(dppe)RuCtC}Fc′ (10). A mix-
ture of RuCl(dppe)Cp* (197 mg, 0.294 mmol), 1,1′-(Me3SiCt
C)2Fc′ (106 mg, 0.28 mmol), and KF (17 mg, 0.293 mmol) was
heated in refluxing MeOH (40 mL) for 16 h. After cooling, the
solid that had separated during the reaction was filtered,
(d) With Os(CtCFc)(dppe)Cp. A mixture of Os(CtCFc)-
(dppe)Cp (59 mg, 0.068 mmol) and tcne (11 mg, 0.082 mmol)

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5253

5254 Organometallics, Vol. 24, No. 22, 2005
Bruce et al.
was stirred in benzene (10 mL) at rt for 24 h. After removal of
solvent under vacuum, purification of the residue by prepara-
tive TLC (acetone-CH2Cl2, 2/98) afforded dark red-brown Os-
{C[dC(CN)2]dCFcdC(CN)2}(dppe)Cp (13-Os) (25 mg, 37%).
Crystals were obtained from CH2Cl2-hexane. Anal. Calcd
(C49H38FeN4OsP2‚0.5CH2Cl2): C, 57.54; H, 3.80; N, 5.42; M,
992. Found: C, 57.58; H, 3.88; N, 4.74. IR (Nujol): ν(CN)
C, 74.56; H, 5.56: M (cation), 1393. Found: C, 74.44; H, 5.60.
1
IR (Nujol): 1650s, 1579m cm-1. H NMR (CDCl3): δ 1.13 (s,
6H, 2 × Me), 2.37-2.42 (m, 8H, 4 × CH2), 3.16, 3.62 (2 × m,
2 × 4H, 2 × C5H4), 5.21 (s, 10H, RuCp), 6.81-6.99, 7.20-7.43
(m, 60H, Ph). 31P NMR (CDCl3): δ 78.05. ES-MS (m/z): 696.5,
M2+
.
(c) With 1,1′-{Cp*(dppe)RuCtC}2Fc′. As in (a) above,
MeI (10 drops, excess), 1,1′-{Cp*(dppe)RuCtC}2Fc′ (40 mg,
0.027 mmol), and Na[BPh4] (31 mg, 0.091 mmol) in thf (10
mL) gave the dark red bis(vinylidene) [1,1′-{Cp*(dppe)Rud
CdCMe}2Fc′][BPh4]2 (19) (57 mg, 93%). Anal. Calcd (C134H126B2-
FeP4Ru2): C, 75.21; H, 5.93: M (cation), 1532. Found: C,
1
2214s, 2199s; also 1508 cm-1. H NMR (CDCl3): δ 2.00-2.50
(m, 4H, CH2), 2.26, 3.98, 4.49, 5.53 (4 × m, 4 × 1H, C5H4),
4.13 (s, 5H, FeCp), 5.03 (s, 5H, OsCp), 6.41-6.47, 7.04-7.14,
7.26-7.58, 7.73, 7.89-7.95 (6 × m, 2 + 3 + 10 + 3 + 2H, Ph).
31P NMR (CDCl3): δ 29.03 (d, J 6.8 Hz), 40.79 (d, J 6.8 Hz)
(AB q). ES-MS (MeOH + NaOMe, m/z): 1015, [M + Na]+; 655,
[Os(dppe)Cp]+.
75.07; H, 5.92. IR (Nujol): 1639s, 1579m cm-1 1H NMR
.
(CDCl3): δ 1.10 (s, 6H, 2 × Me), 1.42 (s, 30H, Cp*), 2.10-2.60
(m, 8H, 4 × CH2), 3.13, 3.69 (2 × m, 2 × 4H, 2 × C5H4), 6.79-
6.94 (m, 15H, Ph), 7.16-7.38 (m, 25H, Ph). 31P NMR (CDCl3):
(e) With Ru(CtCFc)(dppe)Cp*. Similarly, a mixture of
Ru(CtCFc)(dppe)Cp* (79 mg, 0.094 mmol) and tcne (14 mg,
0.11 mmol) in benzene (10 mL) gave Ru{η3-C(CN)2CFcCd
C(CN)2}(dppe-P)Cp* (14) (21 mg, 23%) as a purple solid.
Crystals were obtained from acetone-hexane. Anal. Calcd
(C54H48FeN4P2Ru): C, 66.74; H, 4.98; N, 5.76; M, 1088.
Found: C, 66.86; H, 5.00; N, 5.76. IR (Nujol): ν(CN) 2214m,
2206m; other band at 1588 cm-1. 1H NMR (CDCl3): δ 1.14 (s,
15H, Cp*), 2.35-2.50, 2.52-2.70 (2 × m, 2 × 2H, 2 × CH2),
4.32, 4.50, 4.53, 5.41 (4 × m, 4 × 1H, C5H4), 4.46 (s, 5H, FeCp),
7.30-7.80 (m, 20H, Ph). 31P NMR (CDCl3): δ -9.95 (d, J 29.6),
38.64 (d, J 29.6). ES-MS (positive ion, MeOH + NaOMe, m/z):
2000, [2M + Na]+; 1111, [M + Na]+. As discussed above, the
material contained a small amount of the analogous dppeO
complex, which gave 31P signals at δ 34.33 (d, J 28.7) and 38.64
(d, J 28.7).
(f) 1,1′-{Cp(Ph3P)2RuCtC}2Fc′. A mixture of 1,1′-{Cp-
(Ph3P)2RuCtC}2Fc′ (108 mg, 0.067 mmol) and tcne (28 mg,
0.219 mmol) in benzene (10 mL) was stirred for 48 h at rt.
After removal of solvent, the residue was purified by prepara-
tive TLC (CH2Cl2) to give the tcne adduct as a red solid (63
mg, 70%) as a mixture of isomers 15 and 16 (7/3). Anal. Calcd
(C72H48FeN8P2Ru2): C, 64.29; H, 3.60; N, 8.33. Found: C,
64.18; H, 3.47; N, 8.27. IR (Nujol): ν(CN) 2214s; other band
at 1606m (br) cm-1. Major isomer (15): 1H NMR: δ 4.52 (s,
10H, RuCp), 4.90, 5.00, 5.11, 5.52 [4 × s (br), 4 × 2H, C5H4],
7.39-7.56 (m, 30H, Ph). 31P NMR (CDCl3): δ 40.27. Minor
isomer (16): 1H NMR (CDCl3): δ 4.53 (s, 10H, RuCp), 4.70,
4.98, 5.24, 5.74 (4 × s, 4 × 2H, C5H4), 7.35-7.65 (m, 30H, Ph).
31P NMR (CDCl3): δ 40.29.
δ 75.89. ES-MS (m/z): 766, M2+
.
Structure Determinations. Full spheres of diffraction
data 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 > 4σ(F) being used
in the full matrix least squares refinements. All data were
measured using monochromatic Mo KR radiation, λ ) 0.71073
Å. Anisotropic displacement parameter forms were refined for
the non-hydrogen atoms, (x, y, z, Uiso
) being constrained at
H
estimated values. Conventional residuals R, Rw on |F| are
quoted [weights: (σ2(F) + 0.000nwF2)-1]. Neutral atom complex
scattering factors were used; computation used the XTAL 3.7
program system.32 Pertinent results are given in the figures
(which show non-hydrogen atoms with 50% probability am-
plitude displacement ellipsoids and hydrogen atoms with
arbitrary radii of 0.1 Å) and in the Tables 1, 2, and 8.
Individual diversions in procedure are noted below as Variata.
Variata. 1, 2. These compounds are isomorphous and were
refined in the same coordinate and cell setting.
7. Isotropic displacement parameter forms were refined for
C, O of the solvent molecules, O being assigned here and in 8
on the basis of refinement behavior.
11. Solvent residues were modeled as disordered over a pair
of sites with constrained geometries, total occupancy refining
to 0.725.
After heating complex 15 (35 mg, 0.026 mmol) in refluxing
benzene (20 mL) for 2 days, preparative TLC (silica gel,
acetone-hexane, 1/1) gave the pure 16 as a light red solid (32
mg, 92%). Crystals were obtained from CH2Cl2-hexane. Anal.
Calcd (C72H48FeN8P2Ru2): C, 64.29; H, 3.60; N, 8.33; M, 1346.
Found: C, 64.15; H, 3.50; N, 8.38. ES-MS (MeCN, m/z): 1364,
[M + NH4]+.
14. A difference map residue in the vicinity of the uncoor-
dinated phosphorus was modeled as a phosphine oxide oxygen
impurity fragment, occupancy refining to 0.182(9). Full details
of the structure determination (except structure factors) have
been deposited with the Cambridge Crystallographic Data
Centre as CCDC Nos. 253731-253743, 269428. 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).
Reactions of MeI. (a) With 1,1′-{Cp(Ph3P)2RuCtC}2Fc′.
MeI (10 drops, excess) was added to a suspension of 1,1′-{Cp-
(Ph3P)2RuCtC}2Fc′ (55 mg, 0.034 mmol) and Na[BPh4] (55 mg,
0.161 mmol) in thf (10 mL), and the mixture was heated at
reflux point overnight. After cooling and removal of solvent,
column chromatography (basic alumina, CH2Cl2) gave the dark
red bis(vinylidene) [1,1′-{Cp(Ph3P)2RudCdCMe}2Fc′](BPh4)2
(17) (60 mg, 78%). Anal. Calcd (C144H118B2FeP4Ru2): C, 76.80;
Acknowledgment. We thank the ARC (M.I.B.) and
the EPSRC (P.J.L.) for support of this work and Johnson
Matthey plc, Reading, for a generous loan of RuCl3‚
nH2O. B.G.E. held a Commonwealth Post-graduate
Scholarship; R.L.R. holds a postgraduate scholarship
from the Durham Chemistry EPSRC Doctoral Training
Account. We thank Dr. Azzedine Bousseksou (Toulouse,
France) for fruitful discussions concerning the analysis
1
H, 5.28; M (cation), 1644. IR (Nujol): 1642s, 1579m cm-1. H
NMR (CDCl3): δ 1.85 (s, 6H, 2 × Me), 3.93, 4.28 (2 × m, 2 ×
4H, C5H4), 4.83 (s, 10H, RuCp), 6.86-6.93 (m, 33H, Ph),
7.01-7.06 (m, 17H, Ph), 7.15-7.18 (m, 25H, Ph), 7.35-7.46
(m, 25H, Ph). 31P NMR (CDCl3): δ 42.65. ES-MS (m/z): 822,
M2+
.
(b) With 1,1′-{Cp(dppe)RuCtC}2Fc′. As in (a) above, MeI
(10 drops, excess), 1,1′-{Cp(dppe)RuCtC}2Fc′ (64 mg, 0.047
mmol), and Na[BPh4] (36 mg, 0.105 mmol) in thf (10 mL) gave
the dark red bis(vinylidene) [1,1′-{Cp(dppe)RudCdCMe}2Fc′]-
[BPh4]2 (18) (60 mg, 63%). Anal. Calcd (C120H112B2FeP4Ru2):
(31) Bruce, M. I.; Low, P. J.; Skelton, B. W.; Tiekink, E. R. T.; Werth,
A.; White, A. H. Aust. J. Chem. 1995, 48, 1887.
(32) Hall, S. R., de Boulay, D. J., Olthof-Hazekamp R., Eds. The
XTAL 3.7 System; University of Western Australia: Perth, 2000.

Ferrocenylethynyl Complexes of Fe, Ru, and Os
Organometallics, Vol. 24, No. 22, 2005 5255
of the Mo¨ssbauer spectra and Professor Brian Nicholson
(University of Waikato, New Zealand) for the mass
spectra. This work was facilitated by travel grants from
the Centre National de la Recherche Scientifique (CNRS),
the Australian Research Council (ARC IREX and Link-
age Exchange programs), and the EU EESD HPMT-
CT2001-00311 Marie Curie Training Site (Amsterdam,
The Netherlands).
Supporting Information Available: The crystallographic
data, in cif format, can be obtained free of charge from the
Internet at http://pubs.acs.org.
OM050483L