A comparison of Cp*- and Tp-ruthenium carbyne complexes prepared via site selective electrophilic addition to neutral ruthenium vinylidenes

Article abstract of DOI:10.1016/j.jorganchem.2005.07.040

The synthesis and characterization of a series of ruthenium carbyne complexes supported by either pentamethylcyclopentadienyl (Cp*) or hydridotris(pyrazolyl)borate (Tp) ligands are discussed. Reacting the neutral ruthenium(II) vinylidenes [Cp*Cl(PPh₃)Ru(CCHR)] (1) or [TpCl(PPh₃)Ru(CCHR)] (2) with excess HBF₄ ? Et ₂O yields the ruthenium(IV) carbynes [Cp*Cl(PPh ₃)Ru(CCH₂R)][BF₄] (3: R = ^tBu, 3a; R = ⁿBu, 3b; R = Ph, 3c), and [TpCl(PPh₃)Ru(CCH ₂R)][BF₄] (4: R = ^tBu, 4a; R = ⁿBu, 4b; R = Ph, 4c). Complexes 3a and 3b are isolable solids, whereas 3c and 4a-c must be prepared and examined in solution at low temperatures using variable temperature NMR spectroscopy. In contrast, reactions of 1 or 2 (R = Ph) with MeOTf selectively yield the chloride abstracted products [Cp*(OTf) (PPh₃)Ru(CCHPh)] (5) or [Tp(OTf)(PPh₃)Ru(CCHPh)] (6), respectively, along with one equivalent of MeCl. When R = ^tBu or ⁿBu, the reactions are much less selective. The relative stabilities of the complexes reported are compared and discussed.

Full text of DOI:10.1016/j.jorganchem.2005.07.040

Journal of Organometallic Chemistry 690 (2005) 4640–4647
www.elsevier.com/locate/jorganchem
A comparison of Cp*- and Tp-ruthenium carbyne
complexes prepared via site selective electrophilic addition
to neutral ruthenium vinylidenes
*
Nicholas J. Beach, Andrew E. Williamson, Gregory J. Spivak
Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ont., Canada P7B 5E1
Received 10 May 2005; received in revised form 8 July 2005; accepted 11 July 2005
Available online 19 August 2005
Abstract
The synthesis and characterization of a series of ruthenium carbyne complexes supported by either pentamethylcyclopentadienyl
(Cp*) or hydridotris(pyrazolyl)borate (Tp) ligands are discussed. Reacting the neutral ruthenium(II) vinylidenes [Cp*Cl(PPh3)-
Ru(CCHR)] (1) or [TpCl(PPh3)Ru(CCHR)] (2) with excess HBF4 Æ Et2O yields the ruthenium(IV) carbynes [Cp*Cl(PPh3)Ru-
(CCH2R)][BF4] (3: R = tBu, 3a; R = nBu, 3b; R = Ph, 3c), and [TpCl(PPh3)Ru(CCH2R)][BF4] (4: R = tBu, 4a; R = nBu, 4b;
R = Ph, 4c). Complexes 3a and 3b are isolable solids, whereas 3c and 4a–c must be prepared and examined in solution at low tem-
peratures using variable temperature NMR spectroscopy. In contrast, reactions of 1 or 2 (R = Ph) with MeOTf selectively yield the
chloride abstracted products [Cp*(OTf)(PPh3)Ru(CCHPh)] (5) or [Tp(OTf)(PPh3)Ru(CCHPh)] (6), respectively, along with one
n
equivalent of MeCl. When R = tBu or Bu, the reactions are much less selective. The relative stabilities of the complexes reported
are compared and discussed.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Vinylidene; Carbyne; Electrophilic addition; Pentamethylcyclopentadienyl; Hydridotris(pyrazolyl)borate
1. Introduction
and derivatives. One might also compare ring-slippage
[3] in C5R5 ligands to the ability of the Tp ligand to dis-
sociate a pendant pyrazolyl arm, where in each case an
electron pair is removed from the metal, and a vacant site
is created. There are, however, a number of notable dif-
ferences between the two ligand classes as well. For
example, the Tp ligand has a lower field strength com-
pared to C5R5 [4]. The Tp ligand tends to bind to metals
using its r-donor orbitals, which contrasts the p-fashion
established for C5R5 ligands. The Tp ligand is also bulk-
ier, with a calculated cone angle [5] of about 180ꢁ, com-
pared to 146ꢁ for Cp* and 100ꢁ for Cp. The thermal and
chemical properties of their respective complexes are, in
many cases, notably different [1c].
The hydridotris(pyrazolyl)borate (HB(pz)3, or Tp) [1]
and the cyclopentadienyl-type (C5R5, in particular C5H5,
or Cp, and C5Me5, or Cp*) [2] ligand classes are featured
prominently in transition metal chemistry as excellent
spectator ligands since both classes typically bind
strongly to metals, and they are also generally resistant
towards nucleophilic and electrophilic attack. Several
comparisons may be drawn between Tp and C5R5 li-
gands. For example, both ligand classes are isoelectronic,
bear a net negative charge, and are capable of forming
structurally analogous (e.g., half-sandwich) complexes
In recent years, a number of reports have appeared in
the literature describing the synthesis of ruthenium
carbyne complexes [6]. The majority of these reports
*
Corresponding author. Tel.: +1 807 343 8297; fax: +1 807 346
7775.
E-mail address: greg.spivak@lakeheadu.ca (G.J. Spivak).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.07.040

N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
4641
have centred on synthesis and reactivity. At the mo-
ment, little effort has been directed towards understand-
ing those factors which control the stability of
ruthenium carbynes. We recently communicated some
preliminary results on the synthesis of ruthenium car-
byne complexes prepared via selective electrophilic at-
tack on vinylidene precursors [6j]. The complexes
described in that report are supported by the Cp* li-
gand. We envisioned the Cp* ligand would serve as a
better candidate than Cp for supporting the p-acid car-
byne ligand [7], given its enhanced electron donating
character. It has been suggested [4] that the Tp ligand
is more closely related to the Cp* ligand than the Cp li-
gand. Within this context, we became interested in
extending our work on ruthenium carbynes to include
the Tp spectator ligand, with the intent to explore fur-
ther those factors which influence the stability and reac-
tivity of ruthenium carbyne complexes. The present
study described herein, which builds upon our previous
work [6j], compares the stability and reactivity of ruthe-
nium carbyne complexes supported by either Cp* or Tp.
undergo regioselective electrophilic attack at Cb of the
vinylidene ligand when treated with an excess of
HBF4 Æ Et2O to yield respectively the ruthenium(IV) car-
bynes [Cp*Cl(PPh3)Ru(CCH2R)][BF4] (3: R = tBu, 3a;
R = nBu, 3b; R = Ph, 3c), and [TpCl(PPh3)Ru(CCH2R)]-
[BF4] (4: R = tBu, 4a; R = nBu, 4b; R = Ph, 4c), as illus-
trated in Scheme 1.
We wanted to probe further the mechanism of forma-
tion of carbynes 3 and 4, and determine the course of
electrophilic addition to 1 and 2 (i.e., distinguish kinetic
vs. thermodynamic protonated products) using variable
temperature NMR spectroscopy. Molecular orbital cal-
culations suggest electrophiles might add selectively to
Cb of a vinylidene ligand when bound to a late transition
metal [10]. However, attack of the electrophile could oc-
cur initially at the electron-rich metal centre, yielding a
hydrido vinylidene kinetic product [11]. Conceivably,
electrophilic attack might also occur initially at a ligand
(e.g., halide) [12]. In either case, intramolecular proton
migration to Cb of the vinylidene ligand would yield
the carbyne products observed. Carbynes 3 and 4 are
formed rapidly, cleanly and quantitatively even at
ꢀ70 ꢁC (NMR). All display varying degrees of stability
(vide infra). In all cases, electrophilic addition was ob-
served to occur selectively at Cb of the vinylidene ligand
under the conditions employed. Unfortunately, no inter-
mediate species were observed under these conditions,
hence the mechanism remains unclear. Similar difficul-
ties in discerning kinetic vs. thermodynamic protonation
sites have been reported for other ruthenium vinylidene
systems [6f].
2. Results and discussion
2.1. Synthesis of the carbynes
[Cp*Cl(PPh3)Ru(CCH2R)][BF4] (3) and
[TpCl(PPh3)Ru(CCH2R)][BF4] (4)
The neutral ruthenium(II) vinylidenes [Cp*Cl(PPh3)
Ru(CCHR)] (1) [8] and [TpCl(PPh3)Ru(CCHR)] (2) [9]
Scheme 1.

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N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
NMR spectroscopic data for complexes 3 and 4 were
through the complexes [LRuCl(CO)(PPh3)] (L = g3-Tp,
CO = 1958 cmꢀ1
acquired in the range ꢀ70 to 22 ꢁC depending on stabil-
ity, and in all cases, they are consistent with the forma-
tion of a carbyne ligand. Key spectroscopic features for
3 and 4 include the signals attributed to the carbyne car-
bons, which appear as low-field (d 340.6–355.2 ppm)
doublets in their respective 13C{1H} NMR spectra due
to coupling with the adjacent PPh3 ligand. The mea-
sured 2JPC couplings (15.7–18.2 Hz) for 3 and 4 are low-
er compared to the parent vinylidenes 1 and 2 (19.2–
24.4 Hz) [8,9] which suggests diminished backbonding
with the PPh3 ligand upon oxidizing the metal. Also,
t t
CO = 1965 cmꢀ1 [16]; L = g5-Cp,
[17]; L = g5-Cp*, tCO = 1918 cmꢀ1 [18]). Similar effects
have been observed in ruthenium dihydrogen com-
plexes, where increasingly stronger donor co-ligands
yield an increase in H–H separation [19]. Thus,
[CpRu(g2-H2)(dppe)]+ (dppe = Ph2PCH2CH2PPh2) has
a
more ‘‘stretched’’ H–H bond (1JHD = 24.9 Hz,
2
+
˚
d(HH)calc ꢃ 1.00 A) [19] than [TpRu(g -H2)(dppe)]
(1JHD = 32.5 Hz, d(HH)calc ꢃ 0.88 A) [20]. An increase
in electron density at the metal centre should also trans-
late into longer C–C bonds for metal-bound p-co-li-
gands. For example, the average C–C distance
observed for the g4-butadiene ligand in [TpRu(g4-buta-
˚
2
the relatively low values of JPC observed for 3 and 4
are consistent with a carbyne ligand located in a cis po-
sition with respect to the PPh3 ligand. The two methy-
lene hydrogens on Cb of the carbyne ligands are
diastereotopic, due to the chiral ruthenium centres in
complexes 3 and 4. Consistent with this inequivalency,
each of the carbyne methylene hydrogens in complexes
3a–c, 4a and 4c appear as separate signals in their
˚
diene)Cl] (d(CC)avg ꢃ 1.348 A) [21] is smaller than those
observed for [Cp*Ru(g4-butadiene)X] (X = OTf,
˚
d(CC)avg ꢃ 1.376 A [22]; X = CF3CO2, d(CC)avg
ꢃ
˚
˚
1.393 A [22]; X = I, d(CC)avg ꢃ 1.413 A [23]). Indeed,
the better donor capacity of Cp* is reflected in the
2
slightly stronger JPC couplings observed for the parent
1
respective H NMR spectra. Interestingly, this shift dif-
vinylidenes 1 (23.6–24.4 Hz) when compared to 2 (19.2–
20.1 Hz), however this might also be a function of ligand
size, where the higher steric requirements of the Tp
ligand could be responsible for a slightly weaker
Ru–Ca bond. Nonetheless, the accumulated evidence
suggests Cp* should be better able to stabilize a strongly
p-acidic carbyne ligand and formally Ru(IV) centre in
carbynes 3 and 4.
1
ference is very small and unresolved in the H NMR
spectrum of complex 4b, where the signal for the car-
byne methylene hydrogens appears as a complex multi-
plet within the temperature range ꢀ75 and ꢀ20 ꢁC (the
upper limit of stability for 4b).
Carbynes 3 and 4 were observed to exhibit a range of
stabilities (refer to Scheme 1). Most notably, compounds
3a and 3b are isolable orange solids, and may be obtained
in almost quantitative yields as analytically pure samples
Clearly, the identity of the R group on the carbyne li-
gand has some influence on the overall stability of the
carbyne complex as well. Using as guides the pKa values
for [R3PH]+ [24], enthalpies of protonation for R3P [25],
and the electronic parameter v [26], the substituents
after metathesis with NaBArf (Arf = 3,5-(CF3)2C6H3),
4
f
t
0
ꢁ
to yield ½Cp ClðPPh3ÞRuðCCH2 BuÞꢂ½BAr4ꢂ (3a ) [13]
n
f
0
ꢁ
and ½Cp ClðPPh3ÞRuðCCH2BuÞꢂ½BAr4ꢂ (3b ) (more con-
ventional anion salts such as NaPF6 and NaBPh4 gener-
ally require alcohols as solvents, in which 3a and 3b
proved to be incompatible). Complexes 3a/3a0 and 3b/
3b0 are stable for days when stored at room temperature
under reduced pressure. In contrast, 3c, 4a and 4b may be
quantitatively prepared in solution at ꢀ70 ꢁC, but rap-
idly decompose (when monitored via VT NMR spectros-
copy) in the temperature range ꢀ20 to 0 ꢁC. Complete
decomposition occurs within hours at room temperature.
Compound 4c proved to be the least stable in the series,
and begins to decompose within minutes, despite being
prepared quantitatively and maintained at ꢀ70 ꢁC.
The range of stabilities observed for 3 and 4 is likely
linked to a number of factors. For instance, a series of
EHMO studies conducted by Kirchner et al. [14] sug-
gested electronegative p-donor co-ligands (e.g., chloride)
might destabilize metal-based orbitals which are neces-
sary to bind adjacent p-acid ligands sufficiently. In addi-
tion, the relative electron-donating properties of the Cp*
and Tp co-ligands likely influence the overall stability of
the carbyne complexes as well. IR spectroscopic studies
suggest Cp and Cp* ligands are comparatively better do-
nors with group 8 metals vs. Tp [15]. This is exemplified
n
R = tBu and Bu should be better able to stabilize the
charge generated on Cb upon protonation, while
R = Ph would be the least effective in the series. Thus,
carbyne 3a (with Cp* and R = tBu) is one of the more
stable carbynes in the series, while 4c (with Tp and
R = Ph) is observed to be the least stable.
2.2. Reactions of 1 and 2 with MeOTf
Extending the scope of electrophilic addition reac-
tions to include other electrophiles, in particular Me+,
revealed a different reaction course than that observed
for H+. As well, the reactions were comparatively slower
(minutes) even at room temperature, and poor selectiv-
ity was observed (NMR) in most cases. For example,
we observed that adding excess MeOTf to cooled
(ꢀ78 ꢁC) CD2Cl2 solutions of 1 in an NMR tube, fol-
lowed by gradual warming to room temperature, yielded
a number of interesting results when the reaction was
monitored using VT NMR spectroscopy. With
R = tBu or nBu, the reactions proceeded with poor selec-
tivity despite careful attention to reaction conditions,
and afforded a mixture of products which could not be

N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
4643
confidently assigned. In contrast, when R = Ph the reac-
tion proceeded cleanly under the same conditions, and
quantitatively yielded the triflato vinylidene complex
[Cp*(OTf)(PPh3)Ru(CCHPh)] (5), along with one
equivalent of MeCl within 30 min of mixing at room
temperature, as determined by NMR spectroscopy
(Scheme 1). Complex 5 may be isolated as a relatively
stable brown solid in moderate yields (66%). The
NMR spectra of 5 are similar to that of the parent
chloro vinylidene [Cp*Cl(PPh3)Ru(CCHPh)] [8]. For
example, a low-field Ca vinylidene ligand doublet at d
ties observed among the carbynes studied also
underscores the subtle effects of the identity of the sub-
stituents on the carbyne ligand, with alkyl ligands prov-
ing to be better candidates than aryl ligands. We have
also described an interesting site selectivity in electro-
philic addition reactions to the same ruthenium chloro
vinylidene precursors. The accessibility of sites (i.e.,
chloride or vinylidene) available for attack by an elec-
trophile are likely governed by sterics. Thus, smaller
H+ can access the vinylidene ligand, while larger CH3þ
preferentially attacks chloride.
2
344.3 ppm with JPC = 22.1 Hz (vs. d 340.1 ppm and
2JPC = 24.4 Hz for the chloride analogue) is observed
in the 13C{1H} NMR spectrum of 5, while the Cp*
and vinylidene hydrogen signals resonate at d 1.39 and
d 4.54 ppm (vs. d 1.48 and d 4.51 ppm for the chloride
analogue), respectively. The 19F{1H} NMR spectrum
of 5 shows a singlet at d ꢀ79.1 ppm, consistent with
coordinated OTf [27]. Similar observations were made
when the MeOTf reactions were extended to include
complexes 2 [28]. As with 1, the reactions were slow.
Room temperature NMR data of the products, includ-
ing the evolution of MeCl (1H NMR), suggested
[Tp(OTf)(PPh3)Ru(CCHR)] (R = tBu or nBu) formed
as transient species in varying quantities, however they
were very short-lived (minutes). With R = Ph, the com-
plex [Tp(OTf)(PPh3)Ru(CCHPh)] (6) formed almost
quantitatively (see Section 4) within 90 min, but dis-
played lower stability (t1/2 ꢄ 30 h) compared to the
Cp* analogue 5.
4. Experimental section
All experiments and manipulations were conducted
under an inert atmosphere of prepurified N2 using stan-
dard Schlenk and syringe techniques. Bulk solvents used
in large-scale preparations were rigorously dried, and
either distilled under nitrogen immediately prior to
use, or stored over activated 4A molecular sieves in
bulbs with Teflon taps: CH2Cl2 (CaH2); C6H6, Et2O
and hexanes (sodium metal/benzophenone); MeOH
(activated 4A molecular sieves). NMR solvents used in
solution structure elucidations were dried with appro-
priate drying agents, vacuum distilled, freeze–pump–
thaw degassed three times, and stored in bulbs with Tef-
lon taps: CDCl3 (anhydrous CaCl2); CD2Cl2 (CaH2);
C6D6 (sodium metal). NMR spectra (1H, 13C, 31P and
19F) were obtained using a Varian Unity INOVA
500 MHz spectrometer, with chemical shifts (in ppm)
referenced to residual protio solvent peaks (1H and
13C), external 85% H3PO4 (31P) or external CFCl3
(19F). Elemental analyses were performed on a CEC
240XA analyzer by the Lakehead University Instrumen-
tation Laboratory. With the exception of R = nBu for 1
for which a synthesis is described below, the neutral
vinylidenes 1 [8] and 2 [9] were prepared as described
in the literature.
Despite the slow production of 5 and 6, we observed
no evidence of carbyne formation. The rather large size
of the Cp*, Tp and PPh3 (cone angle = 145ꢁ [26b]) li-
gands likely prevent the comparatively larger CHþ3 cat-
ion from accessing the vinylidene ligand. Even with
[CpCl(PPh2Ph0)Ru(CCHPh)]
(Ph0 = 2-methylphenyl)
[29] which bears the smaller cyclopentadienyl ligand,
MeCl evolution is still observed under similar conditions
[30]. Bulky ligands are known to direct the site of elec-
trophilic attack even with the smallest electrophile H+
[12]. Direct attack of CHþ3 on the chloride ligand [31]
is certainly likely given the greater accessibility of the
chloride lone pairs.
4.1. Synthesis of [Cp*Cl(PPh3)Ru(CCHnBu)]
The complex [Cp*RuCl(PPh3)2] (0.301 g, 0.379 mmol)
was dissolved in benzene (30 mL) and treated with 5
equivalents of 1-hexyne (217 lL, 1.90 mmol) via syringe.
The orange mixture was refluxed for 30 min while stir-
ring. During this time, the solution turned deep red.
Upon completion, the reaction mixture was cooled to
room temperature and the volatiles were removed under
reduced pressure. The crude product was recrystallized
via slow diffusion from MeOH/CH2Cl2. Yield: 0.133 g
(56%). Anal. Calc. for C34H40ClPRu: C, 66.26; H, 6.56.
Found: C, 66.32; H, 6.81%. 1H NMR (499.9 MHz,
CDCl3, 22 ꢁC): d 8.00–7.00 (m, 15H, Ph), 3.57 (t, 1H,
3JHH = 7.3 Hz, RuCCH), 2.07, (m, 2H, RuCCH(nBu)),
3. Concluding remarks
We have presented a study which describes the syn-
thesis of a series of ruthenium carbyne complexes pre-
pared via selective protonation of their respective
neutral ruthenium chloro vinylidene precursor com-
plexes. We have noted that the relative stabilities of
the carbyne complexes examined may be traced, at least
in part, to the supporting ligands. Our results suggest
the Cp* ligand may be more effective than Tp in stabiliz-
ing ruthenium carbyne complexes. The range of stabili-
4
1.45 (d, 15H, JPC = 1.5 Hz, C5(CH3)5), 1.16 (m, 2H,

4644
N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
RuCCH(nBu)), 1.01 (m, 2H, RuCCH(nBu)), 0.79 (t, 3H,
4.4. Low-temperature observation of
[Cp*RuCl(CCH2(Ph))(PPh3)][BF4] (3c)
3JHH = 7.3 Hz, RuCCH(nBu)). 13C{1H} (125.7 MHz,
2
CDCl3, 22 ꢁC): d 334.7 (d, JPC = 24.4 Hz, RuC),
135.0–127.7 (s, Ph), 106.8 (s, RuCCH(nBu)), 100.8 (s,
C5(CH3)5), 33.94–13.96 (s, nBu), 9.58 (s, C5(CH3)5).
31P{1H} NMR (202.3 MHz, CDCl3, 22 ꢁC): d 50.9 (s,
PPh3).
0.0324 g (0.0509 mmol) of [Cp*RuCl(CCHPh)(PPh3)]
was dissolved in CD2Cl2 (0.4 mL) in a 5 mm NMR tube
fitted with a rubber septum and attached to a vacuum
line. The deep red solution was cooled to ꢀ78 ꢁC and
then treated with 7.4 lL of a 54 wt% solution of HBF4
in Et2O (0.0537 mmol) via syringe. An instant colour
change from deep red to orange was observed. The
sample was immediately transferred to a pre-cooled
(ꢀ75 ꢁC) NMR probe, and data were collected immedi-
ately. Complex 3c was observed to form immediately.
1H NMR (499.9 MHz, CD2Cl2, ꢀ75 ꢁC): d 7.58–6.95
4.2. Synthesis of [Cp*RuCl(CCH2(tBu))(PPh3)][BF4]
(3a)
0.223 g (0.362 mmol) of [Cp*RuCl(CCHtBu)(PPh3)]
was dissolved in CH2Cl2 (3 mL) and the solution was
cooled to ꢀ78 ꢁC. To the cooled, deep red solution
was added a slight excess of HBF4 in Et2O (55 lL of
54 wt% solution, 0.399 mmol) followed by stirring at
this temperature for about 10 min. An immediate col-
our change from red to orange–brown was observed.
The solution was allowed to warm to room tempera-
ture gradually (about 30 min), and then the volatiles
were removed under reduced pressure. The orange res-
idue was washed with Et2O (4 · 5 mL) and dried under
reduced pressure. All attempts to recrystallize the prod-
uct were frustrated by the high solubility of this com-
plex yielding oils, hence sufficiently pure samples for
elemental analysis could not be obtained. Yield:
2
(m, 20H, Ph), 4.05 (d, 1H, JHH = 20.5 Hz, RuC-
2
CHaHbPh), 3.52 (d, 1H, JHH = 20.5 Hz, RuC-
4
CHaHbPh), 1.60 (d, 15H, JPH = 1.5 Hz, C5(CH3)5).
13C{1H} (125.7 MHz, CD2Cl2, ꢀ75 ꢁC): d 340.6 (d,
2JPC = 16.3 Hz, RuC), 133.9–126.8 (s, Ph), 110.9 (s,
C5(CH3)5), 59.7 (s, RuCCH2Ph), 10.0 (s, C5(CH3)5).
31P{1H} NMR (202.3 MHz, CD2Cl2, ꢀ75 ꢁC): d 38.6
(s, PPh3).
4.5. Synthesis of [Cp*RuCl(CCH2(tBu))(PPh3)]-
[B(Arf)4] (3a0)
1
0.229 g (90%). H NMR (499.9 MHz, CD2Cl2, 22 ꢁC):
Complex 3a (0.229 g, 0.325 mmol) in CH2Cl2 (8 mL)
d 7.79–7.30 (m, 15H, Ph), 3.11 (dd, 1H, JHH
=
was treated with NaBArf (0.386 g, 0.436 mmol) in Et2O
2
4
20.3 Hz, JPH = 1.1 Hz, RuCCHaHb(tBu)), 1.86 (dd,
(4 mL) via cannula at room temperature. The addition
was accompanied by the immediate formation of a white
precipitate. After about 20 min of stirring, the solvents
were removed under reduced pressure and the product
was extracted from the resultant orange residue with
CH2Cl2 (3 · 12 mL). Filtration of the combined extracts
through Celite and removal of the solvent from the
filtrate under reduced pressure yielded the analytically
pure product as a dark orange–brown solid. Yield:
0.463 g (96%). Orange crystals of 3a0 could be grown
via slow diffusion (CH2Cl2/hexanes) at ꢀ20 ꢁC. Anal.
Calc. for C66H53BClF24PRu Æ CH2Cl2: C, 51.40; H,
3.55. Found C, 51.21; H, 3.75%. The presence of solvent
was confirmed spectroscopically. 1H NMR (499.9 MHz,
4
1H, JHH = 20.3 Hz, JPH = 3 Hz, RuCCHaHb(tBu)),
2
4
4
1.65 (d, 15H, JPH = 2 Hz, C5(CH3)5), 0.97 (s, 9H,
C(CH3)3). 13C{1H} (125.7 MHz, CD2Cl2, 22 ꢁC): d
2
351.0 (d, JPC = 15.7 Hz, RuC),134.8–129.3 (s, Ph),
110.5 (s, C5(CH3)5), 67.4 (s, RuCCH2(tBu)), 36.6 (s,
CMe3), 30.4 (s, C(CH3)3), 10.0 (s, C5(CH3)5). 31P{1H}
NMR (202.3 MHz, CD2Cl2, 22 ꢁC): d 39.0 (s, PPh3).
4.3. Synthesis of [Cp*RuCl(CCH2(nBu))(PPh3)][BF4]
(3b)
A procedure analogous to that for the synthesis of 3a
was employed for the synthesis of 3b, except using
[Cp*Cl(PPh3)Ru(CCHnBu)] (prepared as above) as the
precursor. Unfortunately, as with 3a, all attempts at
recrystallizing 3b yielded only oily products. Yield:
CD2Cl2, 22 ꢁC):
d 7.75–7.45 (m, 27H, Ph and
2
C6H3(CF3)2), 2.51 (d, 1H, JHH = 20.3 Hz, RuC-
CHaHb(tBu)), 1.76 (d, 1H, JHH = 20.3 Hz, RuC-
2
1
4
0.195 g (88%). H NMR (499.9 MHz, CD2Cl2, 22 ꢁC):
CHaHb(tBu)), 1.61 (d, 15H, JPH = 1.5 Hz, C5(CH3)5),
2
d 7.66–7.39 (m, 15H, Ph), 2.35 (m, 1H, JHH = 20.5 Hz,
0.99 (s, 9H, C(CH3)3). 13C{1H} (125.7 MHz, CD2Cl2,
2
2
RuCCHaHb(nBu)), 1.86 (m, 1H, JHH = 20.5 Hz, RuC-
22 ꢁC): d 348.3 (d, JPC = 15.7 Hz, RuC), 161.9 (q,
4
CHaHb(nBu)), 1.56 (d, 15H, JPH = 1.9 Hz, C5(CH3)5),
1JBC = 49.6 Hz, Cipso of Arf), 135.0 (s, Cortho of Arf),
134.5–129.5 (s, Ph), 129.0 (m, Cmeta of Arf), 124.8 (q,
1JCF = 271 Hz, CF3 of Arf), 117.7 (s, Cpara of Arf),
110.6 (s, C5(CH3)5), 67.1 (s, RuCCH2(tBu)), 36.9 (s,
CMe3), 30.4 (s, C(CH3)3), 10.1 (s, C5(CH3)5). 19F{1H}
NMR (470.2 MHz, CD2Cl2, 22 ꢁC): d 63.2 (s, CF3 of
Arf). 31P{1H} NMR (202.3 MHz, CD2Cl2, 22 ꢁC): d
38.3 (s, PPh3).
1.48–1.09 (m, 6H, RuCCH2(nBu)), 0.77 (t, 3H,
3JHH = 7 Hz, Ru/CCH2(nBu)). 13C{1H} (125.7 MHz,
2
CD2Cl2, 22 ꢁC): d 349.4 (d, JPC = 17.1 Hz, RuC),
135.8–129.2 (s, Ph), 110.6 (s, C5(CH3)5), 66.1 (s,
RuCCH2(nBu)), 31.6 (s, nBu), 24.3 (s, nBu), 22.2 (s,
n
nBu), 13.7 (s, Bu), 10.0 (s, C5(CH3)5). 31P{1H} NMR
(202.3 MHz, CD2Cl2, 22 ꢁC): d 38.6 (s, PPh3).

N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
4645
4.6. Synthesis of [Cp*RuCl(CCH2(nBu))(PPh3)]-
[B(Arf)4] (3b0)
4.8. Low-temperature observation of [TpRuCl(CCH2-
(nBu))(PPh3)][BF4] (4b)
A procedure analogous to that for the synthesis of 3a0
was employed for the synthesis of 3b0, except using 3b as
the precursor. Complex 3b0 was isolated as a dark or-
ange–brown solid. Unfortunately, the extreme solubility
of 3b0 confounded all attempts at obtaining sufficiently
pure samples for elemental analysis. Yield: 0.407 g
0.0428 g (0.0617 mmol) of [TpRuCl(CCH(nBu))
(PPh3)] in an NMR tube fitted with a rubber septum
was dissolved in CD2Cl2 (0.35 mL) under N2. The sam-
ple was cooled to ꢀ78 ꢁC and then treated with 12 lL of
a 54 wt% solution of HBF4 in Et2O (0.0648 mmol) via
syringe. An instant colour change from deep red to or-
ange–brown was observed. The sample was rapidly
transferred to a precooled (ꢀ75 ꢁC) NMR probe, and
NMR data were collected immediately. Complex 4b
was formed immediately and quantitatively at ꢀ75 ꢁC.
The sample was slowly warmed to room temperature.
Product decomposition began at ꢀ20 ꢁC, with complete
decomposition occurring within hours. 1H NMR
1
(99%). H NMR (499.9 MHz, CD2Cl2, 22 ꢁC): d 7.66–
7.39 (m, 27 H, Ph and C6H3(CF3)2), 2.35 (m, 1H,
2JHH
=
20.5 Hz, RuCCHaHb(nBu)), 1.86 (m, 1H,
2JHH = 20.5 Hz, RuCCHaHb(nBu)), 1.56 (d, 15H,
4JPH = 1.9 Hz, C5(CH3)5), 1.48–1.09 (m, 6H, RuCCH2
(nBu)), 0.77 (t, 3H, JHH = 7 Hz, RuCCH2(nBu)).
3
13C{1H} (125.7 MHz, CD2Cl2, 22 ꢁC): d 347.0 (d,
2JPC = 17.1 Hz, RuC), 162.0 (q, JBC = 49.6 Hz, Cipso
(499.9 MHz, CD2Cl2, ꢀ70 ꢁC):
d
7.89 (d, 1 H,
1
of Arf), 135.0 (s, Cortho of Arf), 135.8–128.1 (s, Ph),
3JHH = 1.5 Hz, Tp), 7.84 (d, 1 H, JHH = 2 Hz, Tp),
3
129.1 (m, Cmeta of Arf), 124.8 (q, JCF = 271 Hz, CF3
7.82 (d, 1H, JHH = 2.5 Hz, Tp), 7.77 (s, 1H, Tp),
1
3
of Arf), 117.7 (s, Cpara of Arf), 110.7 (s, C5(CH3)5), 66.1
7.62–7.28 (m, 15H, Ph), 7.09 (s, 1H, Tp), 6.36 (s, 1H,
(s, RuCCH2(nBu)), 31.6 (s, Bu), 24.3 (s, Bu), 22.1 (s,
Tp), 6.21 (d, 1H, JHH = 2Hz, Tp), 5.99 (m, 2H,
n
n
3
nBu), 13.5 (s, Bu), 10.1 (s, C5(CH3)5). 19F{1H} NMR
3JHH = 2Hz, Tp), 3.12–2.96 (m, 2H, RuCCH2(nBu)),
1.92 (br m, 2H, RuCCH2(nBu)), 1.55 (br m, 2H,
RuCCH2(nBu)), 1.10 (br m, 2H, RuCCH2(nBu)), 0.73
n
(470.2 MHz, CD2Cl2, 22 ꢁC): d ꢀ63.2 (s, CF3 of Arf).
31P{1H} NMR (202.3 MHz, CD2Cl2, 22 ꢁC): d 38.6 (s,
PPh3).
2
(t, 3H, JHH = 7 Hz, RuCCH2(nBu)). 13C{1H} NMR
2
(125.7 MHz, CD2Cl2, ꢀ70 ꢁC): d 351.2 (d, JPC
=
4.7. Low-temperature observation of [TpRuCl(CCH2-
(tBu))(PPh3)][BF4] (4a)
17.5 Hz, RuC), 146.8 (s, Tp), 143.5–129.3 (m, Ph),
138.2 (s, Tp), 138.1 (s, Tp), 137.2 (s, Tp), 126.6 (s,
4
Tp), 126.2 (s, Tp), 108.3 (s, Tp), 107.7 (d, JPC = 3 Hz,
0.0333 g (0.0480 mmol) of [TpRuCl(CCH(tBu))
(PPh3)] was degassed in an NMR tube fitted with a rub-
ber septum, and dissolved in CD2Cl2 (0.4 mL) under N2.
The deep red solution thus formed was then cooled to
ꢀ78 ꢁC and treated with 9 lL of a 54 wt% solution of
HBF4 in Et2O (0.0653 mmol) via syringe. The sample
was then rapidly transferred to a precooled (ꢀ70 ꢁC)
NMR probe and immediate acquisition of data was then
carried out. Quantitative conversion to 4a was observed
at ꢀ70 ꢁC. The sample was slowly warmed to room tem-
perature. Product decomposition began at ꢀ20 ꢁC with
complete decomposition into unidentified species ob-
served after several hours. 1H NMR (499.9 MHz,
Tp), 106.9 (s, Tp), 58.1 (s, RuCCH2(nBu)), 32.0 (s,
RuCCH2(nBu)), 23.2 (s, RuCCH2(nBu)), 22.5 (s,
RuCCH2(nBu)), 14.2 (s, RuCCH2(nBu)). 31P{1H}
NMR (202.3 MHz, CD2Cl2, ꢀ70 ꢁC): d 26.4 (s, PPh3).
4.9. Low-temperature observation of [TpRuCl(CCH2-
(Ph))(PPh3)][BF4] (4c)
0.0239 g (0.0335 mmol) of [TpRuCl(CCH(Ph))(PPh3)]
in an NMR tube fitted with a rubber septum was dis-
solved in CD2Cl2 (0.4 mL) under N2. The resulting deep
red solution was then cooled to ꢀ78 ꢁC and treated with
5 lL of
a 54 wt% solution of HBF4 in Et2O
3
CD2Cl2, ꢀ70 ꢁC): d 7.97 (d, 1H, JHH = 1.5 Hz, Tp),
(0.0363 mmol) via syringe. A rapid colour change from
deep red to orange–brown was observed. The cooled
sample tube was then transferred immediately to a pre-
cooled (ꢀ70 ꢁC) NMR probe and data were acquired
immediately. Complex 4c was observed to have formed
immediately and quantitatively at ꢀ70 ꢁC. Slow decom-
position of 4c began almost immediately at ꢀ70 ꢁC.
Slowly warming the solution to room temperature only
accelerated the decomposition of 4c, which was observed
7.84 (s, 2H, Tp), 7.76 (s, 1H, Tp), 7.29 (s, 1H, Tp), 7.6–
7.2 (m, 15H, Ph), 6.35 (s, 1H, Tp), 6.20 (d, 1H,
3
3JHH = 1.5 Hz, Tp), 6.02 (t, 1H, JHH = 2 Hz, Tp), 5.97
3
2
(t,1H, JHH = 1.5 Hz, Tp), 3.08 (d, 1H, JHH = 21 Hz,
RuCCHaHb(tBu)), 2.94 (d, 1H, JHH = 21 Hz, RuC-
2
CHaHb(tBu)), 1.00 (s, 9H, C(CH3)3). 13C{1H} NMR
2
(125.7 MHz, CD2Cl2, ꢀ70 ꢁC): d 355.2 (d, JPC
=
16.5 Hz, RuC), 146.9 (s, Tp), 143.7–132.9 (m, Ph),
3
1
138.5 (s, Tp), 138.1 (s, Tp), 137.4 (d, JPC = 2.9 Hz,
to be complete after about 2 h at room temperature. H
Tp), 126.3 (s, Tp), 125.9 (s, Tp), 108.6 (s, Tp), 107.6 (d,
4JPC = 1.9 Hz, Tp), 107.0 (s, Tp), 70.8 (s, RuCCH2(tBu)),
35.4 (s, CMe3), 31.1 (s, C(CH3)3). 31P{1H} NMR
(202.3 MHz, CD2Cl2, ꢀ70 ꢁC): d 23.9 (s, PPh3).
NMR (499.9 MHz, CD2Cl2, ꢀ70 ꢁC): d 7.81 (d, 1H,
3
3JHH = 2 Hz, Tp), 7.77 (s, 1H, JHH = 2.5 Hz, Tp),
7.60–7.25 (m, 20 H, Ph), 7.23 (s, 1H, Tp), 7.21 (s, 1H,
3
Tp), 6.32 (s, 1H, JHH = 2 Hz, Tp), 6.20 (d, 1H,

4646
N.J. Beach et al. / Journal of Organometallic Chemistry 690 (2005) 4640–4647
3
3JHH = 2.5 Hz, Tp), 5.97 (t, 1H, 3JHH = 2.5 Hz, Tp), 5.95
(t, 1H, JHH = 2.5 Hz, Tp), 5.93 (m, 1H, JHH = 1 Hz,
Tp), 6.77 (d, 1H, JHH = 1.5 Hz, Tp), 6.45 (d, 1H,
3JHH = 2.3 Hz, Tp), 6.18 (t, 1H, JHH = 2.3 Hz, Tp),
3
3
3
4
2
3
Tp), 4.66 (dd, 1H, JPH = 2 Hz, JHH = 20 Hz, RuC-
6.14 (t, 1H, JHH = 2.3 Hz, Tp), 5.75 (t, 1H,
4
2
4
CHaHb(Ph)), 3.83 (dd, 1H, JPH = 2 Hz, JHH = 20 Hz,
RuCCHaHb(Ph)). 13C{1H} NMR (125.7 MHz, CD2Cl2,
3JHH = 2.3 Hz, Tp), 5.40 (d, 1H, JPH = 3.5 Hz,
RuCCH(Ph)). 13C{1H} NMR (125.7 MHz, CD2Cl2,
2
2
ꢀ70 ꢁC): d 341.4 (d, JPC = 17.8 Hz, RuC), 147.1 (s,
22 ꢁC): d 377.4 (d, JPC = 17.3 Hz, RuC), 147.1 (s,
Tp), 145.6 (d, JPC = 1.9 Hz, Tp), 143.4 (s, Tp), 137.6
(s, Tp), 136.3 (s, Tp), 135.4 (d, JPC = 2.9 Hz,
3
Tp), 143.4 (s, Tp), 138.0–129.5 (m, PPh3), 137.4 (d,
3JPC = 2.9 Hz, Tp), 131.5 (s, RuCCH2(Ph)), 130.2 (s,
RuCCH2(Ph)), 128.6–128.1 (m, RuCCH2(Ph)), 126.5 (s,
Tp), 126.1 (s, Tp), 122.9 (s, Tp), 108.3 (s, Tp), 106.8 (d,
4JPC = 2.9 Hz, Tp), 63.7 (s, RuCCH2(Ph)). 31P{1H}
NMR (202.3 MHz, CD2Cl2, ꢀ70 ꢁC): d 26.6 (s, PPh3).
4
RuCCH(Ph)), 134.3–130.3 (m, PPh3), 134.1–133.9 (m,
RuCCH(Ph)), 131.1–130.2 (m, RuCCH(Ph)), 128.8–
128.5 (m, RuCCH(Ph)), 126.9 (s, Tp), 126.1 (s, Tp),
118.9 (q, 1JCF = 319.3 Hz, CF3SO3), 113.8 (s,
RuCCH(Ph)), 106.7 (s, Tp), 106.2 (s, Tp), 105.7 (d,
4JPC = 2.9 Hz, Tp). 19F{1H} NMR (470.2 MHz,
CD2Cl2, 22 ꢁC): d ꢀ78.9 (s, CF3SO3). 31P{1H} NMR
(202.3 MHz, CD2Cl2, 22 ꢁC): d 37.4 (s, PPh3). IR
(cmꢀ1): 1435 (m), 1409 (m), 1399 (m), 1312 (s, m(SO3)),
1245 (sh), 1225 (s), 1212 (s), 1165 (s), 1117 (m), 1092
(m), 1076 (w), 1050 (s), 1028 (s).
4.10. Synthesis of [Cp*Ru(OTf)(CCHPh)(PPh3)] (5)
In a 10 mL Schlenk tube containing a stir-bar,
0.0460 g (0.0723 mmol) of [Cp*Cl(PPh3)Ru(CCHPh)]
was dissolved in CH2Cl2 (0.5 mL) and treated with
25 lL (0.221 mmol, 3 equivalents) of MeOTf via syr-
inge. An almost immediate colour change from deep
red to dark brown with formation of some brown solid
was observed. The reaction mixture was stirred at room
temperature for 30 min, at which point the volatiles were
removed under reduced pressure. The resultant brown
solid was then washed with hexanes (4 · 5 mL) and al-
lowed to dry in vacuo. Yield: 0.0360 g (66%). Anal.
Calc. for C37H36F3O3PRuSÆ2CH2Cl2: C, 50.93; H,
4.39. Found: C, 51.67; H, 4.64%. The presence of sol-
vent was confirmed spectroscopically. 1H NMR
(499.9 MHz, CD2Cl2, 22 ꢁC): d 7.39–6.89 (m, 20 H,
Acknowledgements
We gratefully acknowledge financial support from
the Lakehead University Senate Research Committee,
and the Natural Sciences and Engineering Research
Council of Canada.
References
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Ph), 4.54 (s, 1H, RuCCH), 1.39 (d, 15H, JPH = 2.0 Hz,
C5(CH3)5). 13C{1H} (125.7 MHz, CD2Cl2, 22 ꢁC): d
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