Nickel-triflate complexes as precursors to reactive cations: Preparation and reactivities of (1-R-mdenyl)Ni(PPh3)(OSO2CF3)

Article abstract of DOI:10.1021/om020558a

The complexes (1-R-indenyl)Ni(PPh₃)(OTf) (OTf = OSO₂CF₃; R = Et (1), i-Pr (2), and Bz (3)) have been prepared by reacting the corresponding Ni-thienyl or Ni-Cl precursors with HOTf (triflic acid) or AgOTf, respectively. The triflate ligand in these complexes undergoes facile displacement by various substrates or ligands to facilitate (a) catalytic dimerization of ethylene, isomerization of 1-hexene, and polymerization of phenylacetylene, or (b) formation of the cationic complexes [(1-R-indenyl)(PPh₃)Ni(L)]⁺ (R = i-Pr (a) and CH₃Ph (b); L = CH₃CN (4), PhCN (5), CO (6), Py (7), CNC(CH₃)₃ (8), PPh₃ (9), and PMe₃ (10)). Compounds 1-10 have been characterized spectroscopically and, in the case of complexes 2, 4a, and 8a, by single-crystal X-ray crystallography.

Full text of DOI:10.1021/om020558a

Organometallics 2002, 21, 5531-5539
5531
Nick el-Tr ifla te Com p lexes a s P r ecu r sor s to Rea ctive
Ca tion s: P r ep a r a tion a n d Rea ctivities of
(1-R-in d en yl)Ni(P P h 3)(OSO2CF 3)
Ruiping Wang, Laurent F. Groux, and Davit Zargarian*
De´partement de Chimie, Universite´ de Montre´al, Montre´al, Qucbec, Canada H3C 3J 7
Received J uly 12, 2002
The complexes (1-R-indenyl)Ni(PPh3)(OTf) (OTf ) OSO2CF3; R ) Et (1), i-Pr (2), and Bz
(3)) have been prepared by reacting the corresponding Ni-thienyl or Ni-Cl precursors with
HOTf (triflic acid) or AgOTf, respectively. The triflate ligand in these complexes undergoes
facile displacement by various substrates or ligands to facilitate (a) catalytic dimerization
of ethylene, isomerization of 1-hexene, and polymerization of phenylacetylene, or (b) formation
of the cationic complexes [(1-R-indenyl)(PPh3)Ni(L)]+ (R ) i-Pr (a ) and CH2Ph (b); L ) CH3CN
(4), PhCN (5), CO (6), Py (7), CNC(CH3)3 (8), PPh3 (9), and PMe3 (10)). Compounds 1-10
have been characterized spectroscopically and, in the case of complexes 2, 4a , and 8a , by
single-crystal X-ray crystallography.
In tr od u ction
complications, we have set out to develop systems
that can act as single-component precursors for the
“initiatorless” generation of the cationic species [IndNi-
(PPh3)]+. Direct access to the latter species would be
expected to simplify mechanistic studies of their reac-
tions and should allow us to determine whether they
are, indeed, the truly active species in the catalytic
reactions.
The importance of transition metal-based cationic
species in catalysis has been amply demonstrated in
numerous studies on olefin polymerization,1 CO/olefin
copolymerization,2 and organic synthesis.3 Our own
studies have implied that the cationic species
[Ind(PPh3)Ni]+, which can be generated in-situ from
Ind(PPh3)NiX (Ind ) indenyl and its substituted deriva-
tives; X ) halide or alkyl), might be the active catalyst
for the oligomerization or polymerization of certain
olefins.4 However, the mechanistic details of these
reactions have proven difficult to study, because the
initiators needed for the in-situ generation of the active
species often undergo unwanted reactions with both the
substrates and the precatalysts. For example, Ag+-based
initiators themselves can promote cationic catalysis with
some substrates such as styrene5 and can oxidize some
transition metal precursors.6 To avoid such potential
In the search for direct access to our target cations,
we have explored a strategy based on systems in which
one coordination site around the Ni center is tempo-
rarily occupied by a hemilabile ligand; displacement of
this ligand by various substrates would release the
cationic species and initiate catalysis. The viability of
this strategy has been demonstrated by preliminary
studies which have shown that compounds such as
[{η3,η1(N)-Ind-CH2CH2NMe2}Ni(PPh3)]+ catalyze the
cationic polymerization of styrene thanks to the hemi-
labile coordination of the tethered amine moiety.7 One
drawback of this system is that the intramolecular
coordination of the amine moiety is fairly competitive
with the intermolecular coordination of the substrate
molecules; as a result, catalysis with this system
requires forcing conditions and is limited to reactive
substrates (e.g., polymerization of styrene proceeds at
high temperatures only).
While our investigations aimed at improving the
catalytic activities of the above-described systems con-
tinue, we have also examined an alternative approach
based on using complexes bearing nonchelating, weakly
nucleophilic ligands such as triflate as precursors to
highly reactive cationic intermediates.8 The present
report describes the preparation and characterization
of the triflate derivatives (1-R-Ind)(PPh3)Ni(OTf) (R )
Et (1), i-Pr (2), and Bz (3)) and discusses their reactivi-
ties with ethylene, 1-hexene, phenylacetylene, and
phenylsilane. The facile substitution of the OTf moiety
in these complexes has given access to the new cationic
(1) (a) J ohnson, L. K.; Killian, C. M.; Brookhart, M. J . Am. Chem.
Soc. 1995, 117, 6414. (b) Mathew, J . P.; Reinmuth, A.; Melia, J .;
Swords, N.; Risse, W. Macromolecules 1996, 29, 2755. (c) Gottfried, A.
C.; Brookhart, M. Macromolecules 2001, 34, 1140. (d) Britovesk, G. J .
P.; Gibson, V. C.; Wass, D. M. Angew. Chem., Int. Ed. 1999, 38, 428.
(e) Ittel, S. D.; J ohnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100,
1169. (f) Mecking, S. Coord. Chem. Rev. 2000, 203, 325. (g) Svejda, S.
A.; J ohnson, L. K.; Brookhart, M. J . Am. Cehm. Soc. 1999, 121, 10634.
(h) Hlatky, G. G.; Turner, H. W.; Eckman, R. R. J . Am. Chem. Soc.
1989, 111, 2728. (i) J ordan, R. F. J . Chem. Educ. 1988, 65, 285. (j)
Sen, A.; Lai, T.-W. Organometallics 1982, 1, 415. (k) Eisch, J . J .;
Piotrowski, A. M.; Brownstein, S. K.; Gabe, E. J .; Lee, F. L. J . Am.
Chem. Soc. 1985, 107, 7219. (l) J ordan, R. F.; Bajgur, C. S. Willett, R.;
Scott, B. J . Am. Chem. Soc. 1986, 108, 7410.
(2) (a) Bianchini, C.; Meli, A. Coord. Chem. Rev. 2002, 225, 35. (b)
Sen, A. Acc. Chem. Res. 1993, 26, 303. (c) Drent, E.; Budzellar, P. Chem.
Rev. 1996, 96, 663.
(3) (a) Bosnich, B. Aldrichim. Acta 1998, 31, 76. (b) Suzuki, K. Pure
Appl. Chem. 1994, 66, 1557.
(4) (a) Vollmerhaus, R.; Be´langer-Garie´py, F.; Zargarian, D. Organo-
metallics 1997, 16, 4762. (b) Fontaine, F.-G.; Zargarian, D. Unpublished
results. (c) The analogous allyl nickel complexes (allyl)Ni(PR3)Cl also
dimerize ethylene and propylene in the presence of initiators such as
AlEtCl2: Wilke, G. Angew. Chem., Int. Ed. Engl. 1988, 27, 185.
(5) Hermans, J . P.; Smets, G. J . Polym. Sci., Part A 1965, 3, 3175.
(6) J ordan, R. F.; LaPointe, R. E.; Bajgur, C. S.; Echols, S. F.; Willett,
R. J . Am. Chem. Soc. 1987, 109, 4111.
(7) Groux, L. G.; Zargarian, D. Organometallics 2001, 20, 3811.
10.1021/om020558a CCC: $22.00 © 2002 American Chemical Society
Publication on Web 11/06/2002

5532 Organometallics, Vol. 21, No. 25, 2002
Wang et al.
Sch em e 1
Sch em e 2
complexes [(1-R-indenyl)(PPh3)Ni(L)]+ (R ) i-Pr (a ) and
CH2Ph (b); L ) CH3CN (4), PhCN (5), CO (6), Py (7),
CNC(CH3)3 (8), PPh3 (9), and PMe3 (10)), which are also
described herein.
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of (1-R-In d )Ni-
(P P h 3)(OTf). Complexes 1-3 were prepared by two
related approaches. First, the corresponding thienyl
complexes were treated with 1 equiv of triflic acid to
give thiophene and the triflate derivatives as red
powders in ca. 45% yield. A somewhat higher yielding
(50-60%) and more direct path to the triflate com-
pounds involves the reaction of the chloro precursors
with an excess of AgOTf (Scheme 1). It is interesting to
note that the 1-Et-, 1-i-Pr-, and 1-Bz-Ind derivatives are
relatively easy to isolate, whereas the 1-Me-Ind ana-
logue decomposes during isolation to [(1-Me-Ind)Ni-
(PPh3)2]+. This dependence of stability on the increasing
steric bulk of the Ind substituent might imply that the
decomposition proceeds via an associative (presumably
solvent-assisted) displacement reaction instead of a
unimolecular dissociation of OTf.
The structures of complexes 1-3 have been deduced
from their NMR and IR spectra and confirmed by the
results of single-crystal X-ray diffraction studies carried
out on complexes 2 and 3. The main spectroscopic
features of the OTf complexes are as follows. The
observation of an asymmetric sulfonyl stretching mode
at 1324 cm-1 in the IR spectra and a singlet resonance
at ca. -80 ppm in the 19F NMR spectra of 1-3 support
the presence in these compounds of an η1-coordinated
triflate group.9 The 1H NMR spectra exhibit the an-
ticipated signals for the diastereotopic IndCH2 and
IndCH(CH3)2 protons. Comparison to the 1H NMR
spectra of the precursors revealed that the signals for
H3 (labeling shown on ORTEP figures) resonate more
upfield in 1-3 than in the Ni-thienyl (ca. 4.0 ppm) and
Ni-Cl (ca. 3.3 ppm) analogues. The same trend is also
observed for the 31P{1H} NMR signals: 29 ppm for the
OTf complexes versus 37 and 31 ppm for the thienyl
and Cl analogues, respectively. These findings are
consistent with an empirical trend we have noted10 for
the complexes IndNi(PPh3)(X), according to which the
1H and 31P NMR signals due to H3 and PPh3 both move
upfield as the nucleophilicity of the ligand X decreases
(Me > Et > CC-Ph, 2-thienyl > PhS, phthalimidate, I
> Br > Cl > OTf). Comparing the solution NMR data
for the OTf complexes 1-3 to those obtained previously
for this family of indenyl nickel complexes allows us to
predict relatively long Ni-P distances and nonsym-
metrical (η1, η2) Ind-Ni bonding in their solid state
structures. These predictions are borne out by the
results of the crystallographic studies carried out on 2
and 3, which will be discussed later along with the solid
state structures of the cationic adducts derived from
these complexes (vide infra).
Tr ifa lte Su bstitu tion Rea ction s. We were inter-
ested in the possibility of converting the OTf complexes
into cationic complexes or reactive intermediates via the
exchange of the OTf moiety by ligands of varying
nucleophilicities (PR3, CO, :CNR, :NCR, olefins, alkynes,
silanes, etc.). Experiments showed that displacement of
OTf by a variety of ligands takes place at room tem-
perature to give the corresponding cationic complexes
[(1-R-Ind)Ni(PPh3)(L)][OTf] or initiate catalysis (Scheme
2). A description of the new cationic adducts is presented
below, followed by a discussion of the reactivities of the
Ni-OTf precursors with some substrates. Although the
kinetics of these reactions have not been studied yet,
we suspect that displacement of OTf in these compounds
proceeds via an associative mechanism similar to that
of phosphine substitution in the Ni-Cl analogues.11
[(1-R-In d )Ni(P P h 3)L]+. A number of cationic com-
plexes have been obtained from the displacement of the
OTf moiety in complexes 1-3 by various ligands L (L
) CH3CN (4), PhCN (5), CO (6), Py (7), CNC(CH3)3 (8),
PPh3 (9), and PMe3 (10)). Monitoring by NMR showed
that most of the OTf substitution reactions are very
rapid and give the expected products quantitatively;
however, reactions involving the ligands :CNBut and CO
gave additional products, which will be discussed sepa-
rately (vide infra). Compounds 4a , 6a , 7a , 8a , and 9a
have been isolated as yellow solids in ca. 50-75% yields.
Complete characterization by NMR and IR spectroscopy
and, in the case of 4a and 8a , by X-ray crystallorgraphy
(8) The facile dissociation of the triflate ligand under mild conditions
is known to generate reactive cations. For some examples of the use
of triflate compounds as precursors to strong Lewis acids in organic
synthesis see: (a) Kobayashi, S.; Hachiya, I.; Takahori, T. Synthesis
1993, 371, and references therein. (b) Hollis, T. K.; Bosnich, B. J . Am.
Chem. Soc. 1995, 117, 4570, and references therein. (c) Tanabe, Y.;
Mukaiyama, T. Chem. Lett. 1984, 1867. (d) Tanabe, Y.; Mukaiyama,
T. Chem. Lett. 1984, 673. For some examples of the use of triflate
complexes as precursors to cationic intermediates reactive toward C-H
bonds see: (e) Burger, P.; Bergman, R. G. J . Am. Chem. Soc. 1993,
115, 10462. (f) Alaimo, P. J .; Bergman, R. G. Organometallics 1999,
18, 2707. (g) Alaimo, P. J .; Arndtsen, B. A.; Bergman, R. G. Organo-
metallics 2000, 19, 2130.
(10) Zargarian, D. Coord. Chem. Rev. 2002, in press.
(11) Fontaine, F.-G.; Dubois, M.-A.; Zargarian, D. Organometallics
2001, 20, 5156.
(9) (a) Lawrance, G. A. Chem. Rev. 1986, 86, 17. (b) Braun, T.;
Parsons, S.; Perutz, R. N.; Voith, M. Organometallics 1999, 18, 1710.

Nickel-Triflate Complexes
Organometallics, Vol. 21, No. 25, 2002 5533
Sch em e 3
has confirmed the structural features attributed to these
complexes and, by extension, to the analogues which
have been studied by spectroscopy only. Some of the
observed spectroscopic features reveal important bond-
ing patterns and will be discussed below.
The 31P{1H} NMR spectra of the cations 4-8 show
the expected singlet resonance for the PPh3 ligand in a
narrow chemical shift range (32-38 ppm), while the
spectra of complexes 9 and 10 show additional signals
reflecting the presence of two inequivalent phosphine
ligands. For example, an AB pattern (2J P-P ) 25.5 Hz)
was observed for complexes 9; this is in agreement with
the inequivalence of the two PPh3 groups caused by the
absence in these molecules of a plane of symmetry. For
of free CO (2149 cm-1 14
and intermediate between the
)
corresponding values reported for the anionic complex
[Ni(CO)(SR)3]- (2043 cm-1; R ) 2-thienyl)15 and the
cationic complex [(PPh3)2PtCl(CO)]+ (2100 cm-1).16 We
conclude that there is a fairly strong π-back-bonding
between CO and Ni in complex 6a . Interestingly, the
ν(CN) absorption band in 8a (2196 cm-1) is at a higher
energy than the free ligand (2136 cm-1). This observa-
tion is consistent with the notion that removal of
electron density from the isocyanide ligand’s “lone pair”
(or 5σ′ orbital), which has some degree of antibonding
character with respect to the C-N bond, results in an
increase in the C-N bond order.17 Thus, the high energy
of the ν(CN) absorption band in 8a is likely caused by
the strong σ-donation from :CNBut to the cationic Ni
center in 8a . It is noteworthy that a large ν(CN) value
(2175 cm-1) is also reported for the analogous (but
neutral) complex (η5-C2B9H10CH2NMe2)Ni(CNBut),18
thus confirming that isocyanide ligands are stronger
σ-donors and weaker π-acceptors compared to CO.
As mentioned earlier, reactions of the OTf complexes
with CO and :CNBut gave species other than the simple
OTf substitution products. In the case of the CO
reactions, for instance, the IR spectra showed a second,
less intense absorption band at ca. 1995 cm-1 along with
the main absorption band for the anticipated CO
complex. In the case of the :CNBut reactions, the
31P{1H} NMR spectra of the reaction mixtures showed
that using substoicheometric amounts of ligand gives
only the products of the simple substitution reaction
(signals at 38.11 and 38.25 ppm for 8a and 8b, respec-
tively); on the other hand, using one or more equivalents
of :CNBut gives increasing amounts of a second species
that displayed new signals at 49.50 and 49.49 ppm,
respectively, for the reactions of 2 and 3. We suspect
that the unidentified products of these reactions are the
complexes trans-[(η1-1-R-Ind)(PPh3)NiL2]+ (L ) CO,
CNBut), which would arise from the coordination of a
second equivalent of the isocynaide or CO ligands and
the concomitant slippage of the Ind ligand to an η1 mode.
This proposal is based on a similar reactivity reported
for the reaction of the complex (η-Ind)Pd(PMe3)-
(CH2SiMe3) with :CNBut, which gives the indenyl-
fulvene product shown in Scheme 3. The course of the
latter reaction involves slippage of the Ind ligand
(η3fη1) caused by the coordination of two :CNBut
molecules, followed by insertion of one :CNBut into the
Pd-(η1-Ind) bond and H-shift.19 We believe that in the
case of our complexes the insertion step does not take
complexes 10, we observed an AA′BB′ pattern (2J P-P
)
42 Hz) attributed to the two rotamers of each molecule,
one rotamer with the Ind substituent above PMe3, the
other above PPh3. These spectral patterns are con-
sistent with those reported previously for the 1-Me-Ind
analogues.4a The 13C{1H} NMR spectra displayed the
expected signals for Ind and PPh3 carbons in addi-
tion to those for ligands L. For instance, the CO adduct
6a gave rise to a doublet at ca. 190 ppm (2J P-C ) 16.8
Hz).
The 1H NMR spectra of the new complexes also
contained the expected signals for L, in addition to the
PPh3 and Ind signals characteristic of this family of
complexes. For instance, in the case of the CH3CN
adduct 4a a singlet at 1.99 ppm was assigned to
CH3CN; the absence of this signal in the 1H NMR of
the CD3CN adduct (4a ′) confirmed this assignment. As
discussed earlier for the Ni-OTf complexes, the chemical
shift of the signal for H3 is particularly informative on
the Ind hapticity in these complexes. For instance,
previous studies have shown10,12 that for the complexes
IndNi(PR3)X strong donor ligands X (e.g., alkyl groups)
bring about increasingly symmetrical coordination of the
Ind ligand; this, in turn, results in more downfield
signals for H3, consistent with greater sp2 character on
C3. A comparison of the H3 chemical shifts for the
cationic adducts reveals a similar pattern; that is, strong
ligands give rise to more downfield signals: CO (5.53
ppm) > PPh3 (5.13 ppm) > CNC(CH3)3 (4.80 ppm) >
PhCN (4.30 ppm) ≈ Py (4.21 ppm) ≈ CH3CN (4.18 ppm).
This order roughly parallels the donating strengths of
these ligands to late metals.13
Finally, the frequencies of the ν(CN) and ν(CO) bands
in the IR spectra of complexes 4, 6, and 8 can be used
to estimate the extent of π-back-bonding between the
ligand L and the Ni center in these cations. Thus, the
energy of the ν(CN) absorption band in 4a (2251 cm-1
)
is little changed from its value in free MeCN (2275
cm-1), implying only a small degree of π-back-bonding
between this weakly π-acidic ligand and the cationic Ni
center. In contrast, the energy of the ν(CO) absorption
band in 6a (2089 cm-1) is significantly lower than that
(12) (a) Huber, T. A.; B.-Garie´py, F.; Zargarian, D. Organometallics
1995, 14, 4997. (b) Bayrakdarian, M.; Davis, M. J .; Reber, C.;
Zargarian, D. Can. J . Chem. 1996, 74, 2115. (c) Huber, T. A.;
Bayrakdarian, M.; Dion, S.; Dubuc, I.; B.-Garie´py, F.; Zargarian, D.
Organometallics 1997, 16, 5811. (d) Dubuc, I.; Dubois, M.-A.; Be´langer-
Garie´py, F.; Zargarian, D. Organometallics 1999, 18, 30. (e) Wang, R.;
Be´langer-Garie´py, F.; Zargarian, D. Organometallics 1999, 18, 5548.
(13) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Fink, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Book: Mill Valley, CA, 1987; p 243.
(14) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; J ohn Wiley & Sons: New York, 1994; p 15.
(15) Liaw, W.; Chen, C.; Lee, C.; Lee, G.; Peng, S. J . Chem. Soc.,
Dalton Trans. 2001, 138.
(16) Collman, J . P.; Hegedus, L. S.; norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987; p 114.
(17) Treichel, P. M. Adv. Organomet. Chem. 1973, 11, 21.
(18) Park, J .; Kim, D.; Kim, S.; Ko, J .; Kim, S.; Cho, S.; Lee, C.;
Kang, S. Organometallics 2001, 20, 4483.

5534 Organometallics, Vol. 21, No. 25, 2002
Wang et al.
Ta ble 1. Cr ysta l Da ta Collection a n d Refin em en t P a r a m eter s for Com p lexes 2, 4a , a n d 8a
2
4a ‚CHCl3
8a
formula
mol wt
C
31H28F3NiO3PS
C33H31F3NO3PS•CHCl3
787.696
C36H37F3NiO3PS
710.406
627.274
cryst color
cryst habit
cryst dimens, mm
cell setting
space group
a, Å
dark red
block
dark yellow
block
dark red
block
0.46 × 0.40 × 0.27
orthorhombic
Pbca
13.571(3)
18.681(4)
28.083(6)
0.74 × 0.48 × 0.24
monoclinic
P21/n
9.1834(1)
20.6114(1)
15.5120(1)
0.76 × 0.49 × 0.37
triclinic
P1h
10.6791(1)
12.8546(1)
14.1394(1)
76.855(1)
75.202(1)
79.150(1)
1809.90(3)
2
b, Å
c, Å
R, deg
â, deg
98.002(1)
γ, deg
V, Å3
2907.57(2)
4
1.4330
1.54178
298(2)
Bruker AXS
SMART
146.16
7120(2)
8
1.3255
1.54178
293(2)
Nonius CAD-4
Z
D(calcd), g cm-3
λ(Cu KR), cm-1
temp, K
diffractometer
1.4454
1.54178
223(2)
Bruker AXS
SMART
145.76
ω/2θ scan
6194
2θmax, deg
139.98
ω/2θ scan
2847
data collecn method
no. of reflns used
(I > 2σ(I))
ω/2θ scan
5556
R, Rw
0.0460, 0.1277
0.0604, 0.1681
0.0353, 0.0484
Ta ble 2. Selected Bon d Dista n ces (Å) for
(1-i-P r -In d )Ni(P P h 3)(OTf) (2),
[(1-i-P r -In d )Ni(P P h 3)(NCCH3)]OTf (4a ), a n d
[(1-i-P r -In d )Ni(P P h 3)(CNC(CH3)3)]OTf (8a )
7
9a
13a
Ni-P
2.1973(6)
1.9404(16)
2.131(2)
2.064(2)
2.024(2)
2.311(2)
2.335(2)
1.410(3)
1.412(4)
1.4543(17)
1.400 (2)
1.422(2)
1.822(3)
1.287(3)
2.1918 (6)
1.869(2)
2.128(2)
2.064(2)
2.013(2)
2.283(2)
2.326(2)
1.410(3)
1.405(4)
2.1838(9)
1.816(3)
2.082(3)
2.066(3)
2.038(3)
2.248(3)
2.248(3)
1.409(3)
1.405(3)
Ni-(O1, N1, C11)
Ni-C1
Ni-C2
Ni-C3
Ni-C3a
Ni-C7a
C1-C2
C2-C3
S-O1
S-O2
S-O3
S-C11
C11-F1
N1-C12
C12-C13
C11-N
C12-N
C12-C13
∆M-Ca
1.132(4)
1.464(4)
1.144(3)
1.464(3)
1.496(7)
0.19
F igu r e 1. ORTEP view of complex 2 with atom labeling;
ellipsoids show 40% probability levels, and hydrogen atoms
have been omitted for clarity.
0.25
0.23
a
∆(M-C) ) 1/2[(Ni-C3a + Ni-C7a) - (Ni-C1 + Ni-C3)].
place since the NMR spectra of the side products contain
the signal due to the Ind H3 proton.
marized in Table 1, while the bond distances and angles
are given in Table 2 and Table 3, respectively. No
rotational disorder was detected for the triflate ligand
in 2, in contrast to what has been observed for a
majority of OTf compounds, including complex 3. The
Ni-O distance of 1.9404(16) Å in 2 is comparable to the
corresponding distances in 3 (1.972(9) Å) and trans-
[Ni(OTf)(2-C5F4N)(PEt3)2] (1.957(2) Å), but longer than
the Ni-O distance in [Ni(OPh)(2-C5F4N)(PEt3)2] (1.894(4)
Å);21 this is consistent with the low nucleophilicity of
OTf compared to OPh. The long Ni-C3a/7a distances
(av 2.32 Å) imply a significant η5fη3 distortion (∆M-C
) 0.25 Å),22 whereas the unequal Ni-C1 and Ni-C3
Solid Sta te Str u ctu r es of 2, 4a , a n d 8a . The solid
state structures of complexes 2, 3, 4a , and 8a have been
determined (R (%) ) 4.6, 6.34, 6.04, and 3.53, respec-
tively). The geometry around the Ni center in these
complexes is intermediate between a two-legged piano
stool (with η3Tη5-Ind) and distorted square planar (with
η1,η2Tη3-Ind). Some of the important structural features
of these complexes are described below; the structure
of complex 3 has been described elsewhere20 and will
not be discussed in detail here.
The ORTEP diagram for 2 is shown in Figure 1. The
crystal data and refinement parameters are sum-
(19) Alias, F. M.; Belderrain, T. R.; Paneque, M.; Poveda, M. L.;
Carmona, E. Organometallics 1998, 17, 5620.
(20) Wang, R.; Groux, L. F.; Zargarian, D. J . Organomet. Chem.
2002, in press.
(21) Braun, T.; Parsons, S.; Perutz, R. N.; Voith, M. Organometallics
1999, 18, 1710.

Nickel-Triflate Complexes
Organometallics, Vol. 21, No. 25, 2002 5535
Ta ble 3. Selected Bon d An gles (d eg) for
(1-i-P r -In d )Ni(P P h 3)(OTf) (2),
[(1-i-P r -In d )Ni(P P h 3)(NCCH3)]OTf (4a ), a n d
[(1-i-P r -In d )Ni(P P h 3)(CNC(CH3)3)]OTf (8a )
2
4a
8a
O1(N1, C11)-Ni-P
O1(N1)-Ni-C3
C3-Ni-P
96.41(6)
163.74(9)
99.63(7)
115.50(14)
106.13(15)
115.28(19)
113.07(14)
99.29(6)
161.31(10)
99.16(8)
96.41(8)
161.54(12)
102.2(9)
O2-S-O1
O2-S-C11
O2-S-O3
O3-S-O1
N1-C12-C13
Ni-N1-C12
Ni-C11-N
C11-N-C12
N-C12-C13
FAa
178.7(3)
172.6(2)
176.3(3)
178.4(3)
110.4(6)
7.69(0.20)
10.06(0.22)
9.19(0.12)
10.50(0.12)
8.13(0.17)
10.63(0.18)
HAa
a
HA (hinge angle) ) angle between the planes defined by C1,
C2, C3 and C1, C3, C3a, C7a; FA (fold angle) ) angle between
the planes defined by C1, C2, C3 and C3a, C4, C5, C6, C7, C7a.
F igu r e 3. ORTEP view of complex 8a with atom labeling;
ellipsoids show 30% probability levels. The anion and
hydrogen atoms have been omitted for clarity.
(CH3CN)23 (1.829(3) and 1.138(5) Å, respectively). On
the other hand, the Ni-C11 bond distance of 1.816(3)
Å in the isocyanide adduct 8a is shorter than the
corresponding Ni-C(sp) bond distance of 1.861(4) Å in
the neutral alkynyl analogue (1-Me-Ind)(PPh3)Ni-
(CC-Ph),12e consistent with the strong interaction be-
tween Ni and the isocyanide ligand as deduced from the
IR data (vide supra).
Previous structural studies carried out on the neutral
and cationic compounds [Ind(PPh3)Ni(X or L)]n+ (n ) 0
with X; 1 with L) have shown that the more strongly
donating ligand X/L results in a shorter Ni-P distance
and stronger, more symmetrical Ni-Ind interactions.10,12
Consistent with this trend, complexes 2, 4a , and 8a
show Ni-P distances of 2.1973(6), 2.1918(6), and
2.1838(9) Å, respectively, and ∆M-C values of 0.25,
0.23, and 0.19 Å, respectively; these data reflect the
relative nucleophilicities of the ligands involved (OTf
< MeCN < (t-Bu)NC). On the other hand, the observed
values of the Ni-C3a and Ni-C7a bond lengths can be
explained in terms of the relative trans influences of
PPh3 and the other ligands. Thus, the greater trans
influence of PPh3 compared to OTf and MeCN gives rise
to somewhat longer Ni-C7a versus Ni-C3a bonds in 2
(2.335(2) vs 2.311(2) Å) and 4a (2.283(2) vs 2.326(2) Å),
while the similar trans influences of PPh3 and :CNBut
results in symmetrical distances in 8a (2.248(3) Å).
Finally, it is important to note that the Ind hapticity
observed in the solid state structure of each complex is
maintained in the solution, as discerned from the
13C{1H} NMR chemical shifts for C3a and C7a, with
more upfield shifts indicating more η5-like hapticity for
the Ind ligand.22a,b Thus, comparison of δav(C3a/C7a)
values shows that the Ind hapticity in these complexes
increases on going from 2 (126.4 ppm) to 4a (124.7 ppm)
to 8a (121.3 ppm).
F igu r e 2. ORTEP view of complex 4a ‚CHCl3 with atom
labeling; ellipsoids show 30% probability levels. The anion,
solvent, and hydrogen atoms have been omitted for clarity.
distances reflect the much greater trans influence of
PPh3 compared to the OTf ligand.
The ORTEP diagrams for complexes 4a and 8a are
shown in Figures 2 and 3, respectively; the OTf anions,
which are disordered over two (in 4a ) and three (8a )
sets of positions, have been omitted for clarity. Rota-
tional disorders were also observed for the cocrystallized
molecule of CHCl3 in 4a and the methyl groups of the
t-Bu fragment in 8a . The acetonitrile and isocyanide
ligands are essentially linear: for 4a , the Ni-N1-C12
and N1-C12-C13 angles are ca. 173° and 179°, respec-
tively, while N1-C12 is ca. 1.13 Å; for 8a , the Ni-
C11-N and C11-N-C12 angles are ca. 176° and 178°,
respectively, while C11-N is ca. 1.14 Å. The Ni-N and
N-C bond lengths are fairly similar in the acetonitrile
adduct 4a (1.869(2) and 1.132(4) Å, respectively) and
the neutral complex (η5-Cp)Ni{Sn(CH(SiMe3)2)(OH)}-
Rea ctivities of th e OTf Com p lexes w ith 1-Hex-
en e a n d Eth ylen e. The reaction of the Ni-OTf complex
2 with 50 equiv of 1-hexene (1.3 M in CDCl3) led to the
formation of 2-hexene over 24 h at room temperature.
The GC/MS analysis of the final mixture did not detect
(22) For
a definition of ∆M-C see footnote of Table 2; for a
comparison of ∆M-C values for M-Ind compounds see: (a) Westcott,
S. A.; Kakkar, A. K.; Stringer, G.; Taylor, N. J .; Marder, T. B. J .
Organomet. Chem. 1990, 394, 777. (b) Baker, R. T.; Tulip, T. H.
Organometallics 1986, 5, 839.
(23) Schneider, J . J .; Hagen, J .; Bla¨ser, D.; Boese, R.; Fabrizi de
Biani, F.; Zanello, P. Kru¨ger, C. Eur. J . Inorg. Chem. 1999, 1987.

5536 Organometallics, Vol. 21, No. 25, 2002
Wang et al.
Sch em e 4
any dimers or oligomers, showing instead hexene as the
main component, in addition to traces of 1,3-(hexenyl,
i-Pr)-indene (M•+ ) 240; M•+ - 15 (CH3); M•+ - 29
(CH2CH3); M•+ - 43 (Pr or i-Pr); M•+ - 57 (Bu); etc.).
The 13C{1H} NMR spectrum exhibited two sets of six
peaks; comparison of these signals to literature values
indicated that the major set corresponds to E-2-
hexene,24 whereas the minor set closely resembles, but
is not the same as, the literature values for Z-2-
hexene.25 This minor product is likely an isomer of
hexene, but its precise identity has not been confirmed
yet.
GC/MS analyses of solutions of 2 (ca. 0.02 M) through
which ethylene had been bubbled for ca. 5 min indicated
the formation of butene(s). Similar experiments were
carried out in CDCl3 (0.03 M) with complexes 1 or 2 in
order to analyze the reaction mixture in-situ by NMR.
The 1H and 13C{1H} NMR spectra of these reactions
showed the presence of E- and Z-2-butene (ca. 4:1),26
while the 31P{1H} NMR spectra showed the presence of
mainly 2 plus a small amount of [(1-Pri-Ind)Ni(PPh3)2]+
(vide supra). GC/MS analyses of these NMR samples
confirmed the presence of butene(s) as well as 1,3-(vinyl,
i-Pr)-indene (M•+ ) 184; M•+ - 15 (CH3); M•+ - 30 (2
CH3); M•+ - 43 (i-Pr); etc.) and 1,3-(vinyl, Et)-indene
(M•+ ) 170; M•+ - 15 (CH3); M•+ - 29 (CH3CH2); etc.).
Taken together, the above results demonstrate that
the Ni-OTf complexes are precatalysts for the dimer-
ization of ethylene and isomerization of 1-hexene. These
reactions are likely initiated via the displacement of OTf
to form the cationic olefin adduct shown in Scheme 4.
The coordination of a second molecule of olefin forces
the Ind ligand into a monohapto mode, followed by the
insertion of one of the coordinated olefins into the Ni-
(1-R-Ind) bond to give [LnNi{CHR′CH2(R-Ind)}]+. The
latter can then undergo â-H elimination to give the
disubstituted indenes, which were detected by GC/MS
analyses, and generate a cationic hydride that is prob-
ably the active catalyst for the dimerization of ethylene
and the isomerization of 1-hexene (Scheme 4). No
dimerization is observed with 1-hexene presumably
because the â-H elimination from the initial product of
insertion (i.e., [LnNi-hexyl]+) is faster than the coordina-
tion of a second molecule of hexene followed by insertion.
Rea ctivities of th e OTf Com p lexes w ith P h CCH,
P h SiH3, a n d P h SiMeH2. The activity of the OTf
complexes in alkyne polymerization was studied by
reacting complex 2 with 200 equiv of Ph-CC-H (in THF
or neat) at 50 °C. The resulting, sparingly soluble yellow
powder (ca. 5% yield) was shown to be poly(phenyl-
acetylene) by GPC analysis (Mw ) 8189, Mn ) 4418, Mw/
Mn ) 1.85). The low solubility and molecular weight of
this material, as well as its featureless 1H NMR
spectrum (broad signals at ca. 6.5-7.8 ppm), contrast
with the properties of the cis,transoidal-poly(phenyl-
acetylene) obtained previously12e from a combination of
(1-Me-Ind)(PPh3)Ni-X and MAO (X ) Cl or CC-Ph;
Ni:Al ratio 1:10); the latter polymers are soluble, have
Mw of ca. (3-5) × 104, and show relatively sharp signals
1
in the vinylic region of the H NMR spectrum. These
findings imply that the active species generated in the
MAO-cocatalyzed reactions12e are not the same as the
cationic species studied here.
The reactivity of 2 with hydrosilanes was probed
briefly by studying the reactions with PhSiH3 and
PhMeSiH2. Addition of 2 to these silanes (both neat and
in C6D6 solutions) resulted in the evolution of H2; the
1H NMR spectra of the final mixtures showed signals
characteristic of the dimers of these silanes.27 These
results show that the cationic precursors tend to dimer-
ize hydrosilanes, in contrast to the oligomerization
activities observed with neutral Ni-Me precursors.28 It
is worth noting that the silane reactions do not seem to
turn over, as they give very low conversions (ca. 2 equiv
1
of silane consumed). Monitoring these reactions by H
NMR spectroscopy did not result in the detection of Ni-H
resonances, but the 31P{1H} NMR spectra showed the
emergence of a few singlets at ca. 35-40 ppm. We
suspect that these resonances might be due to Ni-silyl
intermediates, because derivatives bearing strong σ-
donor ligands such as alkyl, alkenyl, and alkynyl ligands
show 31P signals in the region of 37-48 ppm.
Con clu sion
The present study has shown that the OTf compounds
(1-R-Ind)Ni(PPh3)(OTf), which are prepared from the
corresponding Ni-Cl or Ni-thienyl precursors, can serve
as single-source precursors for generating highly elec-
trophilic cations that dimerize ethylene, PhSiH3, and
(24) The observed peaks: 13.6, 17.9, 22.7, 34.8, 124.7, and 131.4
ppm; the literature values for E-2-hexene: 13.7, 17.7, 23.2, 35.3, 125.1,
131.7: Silverstein, R. M.; Bassler, G. C.; Morrill, T. C. Spectrometric
Identification of Organic Compounds; 1981; p 263.
(25) The observed peaks: 12.4, 13.7, 25.6, 28.9, 123.8, and 130.6
ppm; the literature values for Z-2-hexene: 12.6, 13.7, 22.6, 29.4, 124.0,
137.2: see citation in ref 24.
(26) Two sets of 1H NMR peaks were observed: (a) 5.4-5.5 ppm
(27) (PhSiH2)2 was identified on the basis of the signal at 4.48 ppm,
while (PhMeSiH)2 showed signals at 4.45 ppm (br, 1 H) and 1.20 ppm
3
4
(m) and 1.64 ppm (dd, J H-H ) 4.8 Hz, J H-H ) 1.2 Hz); (b) 5.4-5.5
ppm (m) and 1.61 ppm (q, 3J H-H ) 5.0 Hz). Two sets of 13C NMR peaks
were also observed: (a) 125.8 and 17.8 ppm; (b) 124.6 and 12.4 ppm.
These peaks are close to the literature values for E- (126.0 and 17.6
ppm) and Z- (124.6 and 12.1 ppm) 2-butenes (see citation in ref 24).
3
(d, J H-H ) 6.9 Hz, 3H): (a) Woo, H.-G.; Walzer, J . F.; Tilley, T. D. J .
Am. Chem. Soc. 1992, 114, 7047. (b) Gauvin, F. Ph.D. Thesis, McGill
University, 1992.
(28) Fontaine, F.-G.; Zargarian, D. Organometallics 2002, 21, 401.

Nickel-Triflate Complexes
Organometallics, Vol. 21, No. 25, 2002 5537
was crystallized from CH2Cl2/hexane at room temperature to
give the product as a red powder (68 mg, 44%).
PhMeSiH2, polymerize Ph-CC-H, and isomerize 1-hex-
ene. These results support our previous assertions that
the dimerization of ethylene in systems consisting of
Meth od B. The dark red solution of (1-i-Pr-Ind)Ni(PPh3)-
Cl (256 mg, 0.498 mmol) in CH2Cl2 (25 mL) was added to the
stirring CH2Cl2 (15 mL) suspension of AgOTf (192 mg, 0.747
mmol). The resultant mixture was stirred for 2 h at room
temperature and filtered, and the filtrate was evaporated to
dryness. The residue was crystallized from C6H6/hexane at
room temperature to give the product as a red powder (166
mg, 53%). Recrystallization of a small portion of this solid from
a CH2Cl2/hexane solution at -20 °C yielded crystals suitable
4a
IndNi(PPh3)Cl/AgBF4 or IndNi(PPh3)X/MAO29 invovle
cationic intermediates, while different intermediates are
involved in the polymerization of phenylacetylene12e and
ethylene29 with the MAO-cocatalyzed systems. The
facile substitution of the OTf moiety by a series of Lewis
bases can also give the corresponding cationic adducts,
some examples of which have been isolated and fully
characterized. Studies are underway to probe and
expand the scope of the reactions catalyzed by the OTf
precursors.
1
3
for X-ray diffraction studies. H NMR (C6D6): 1.14 (d, J H-H
3
) 7.0 Hz, -CH(CH3)2), 1.56 (d, J H-H ) 6.5 Hz, -CH(CH3)2),
3
3
2.93 (m, -CH(CH3)2), 3.02 (tet, J H-H ) 2.6 Hz, J P-H ) 4.8
Hz, H3), 6.06 (d, 3J H-H ) 7.8 Hz, H4), 6.14 (d, 3J H-H ) 2.6 Hz,
H2), 6.79 (t, 3J H-H ) 7.9 Hz, H5), 7.01 (m, ArH), 7.18 (s, ArH),
7.51 (m, ArH). 13C{1H} NMR (CDCl3, 300 MHz): 20.07
Exp er im en ta l Section
4
(CH(CH3)2), 20.90 (d, J P-C ) 5.2 Hz, CH(CH3)2), 26.02 (s,
CH(CH3)2), 61.44 (C3), 100.28 (C2), 117.98, 118.26, (d, J P-C
All manipulations and experiments were performed under
an inert atmosphere using standard Schlenk techniques and/
or in a nitrogen-filled glovebox. Dry, oxygen-free solvents were
employed throughout. Bruker AMX400 and AV300 spectrom-
eters were employed for recording 1H (400 MHz), 13C{1H}
(100.56 and 75.42 MHz), 19F (376.31 MHz), and 31P{1H} (161.92
2
) 11.3 Hz, C1), 120.63, 124.96 (C3a), 127.66 (C7a), 127.80,
3
1
128.51, 128.78 (d, J P-C ) 10.3 Hz, m-PPh3), 130.27 (d, J P-C
2
) 44.2 Hz, i-PPh3), 130.91 (s, p-PPh3), 133.99 (d, J P-C ) 11.9
Hz, o-PPh3). 31P{1H} NMR: 29.30 (s) (in C6D6), 28.73 (s)
(CDCl3). 19F{1H} NMR: -79.79 (s) (in C6D6), -81.51 (s) (in
CDCl3). IR (KBr): 1637 (m), 1459 (m), 1481 (m), 1438 (s), 1385
(m), 1324 (m), 1252 (m), 1233 (s), 1213 (s), 1175 (s), 1121 (m),
1097 (m), 1031 (s), 749 (s), 725 (m), 695 (s), 639 (s), 543 (s),
532 (s), 511 (m), 495 (w). FABMS (m/z): 477 (M+ - OTf). Anal.
Calcd for C31H28PNiO3SF3 (627.289): C, 59.36; H, 4.50; S, 5.11.
Found: C, 59.88; H, 4.53; S, 5.07.
1
MHz) NMR spectra at ambient temperature. H and 13C{1H}
spectra are referenced to solvent resonances, 31P{1H} to 85%
H3PO4, 19F to C6H5CF3 (-63.9 ppm). The IR spectra were taken
on a Perkin-Elmer 1750 FTIR (4000-450 cm-1) with sample
prepared as KBr pellets or evaporated films on NaCl plates.
Mass spectrometric measurements were performed by the
Centre Re´gional de Spectrome´trie de Masse de Universite´ de
Montre´al. The elemental analyses were performed by Labo-
ratoire d’Analyse EÄ le´mentaire (Universite´ de Montre´al). (1-
Et-Ind)Ni(PPh3)(thienyl), (1-i-Pr-Ind)Ni(PPh3)(thienyl), (1-i-Pr-
Ind)Ni(PPh3)Cl, (1-Bz-Ind)Ni(PPh3)(thienyl), and (1-Bz-Ind)-
Ni(PPh3)Cl were prepared as described elsewhere.20 CF3SO3Ag,
CF3SO3H, PPh3, PMe3, and CNC(CH3)3 were purchased from
Aldrich and used as received. Pyridine, CH3CN, and PhCN
were purchased from A & C American Chemicals and were
distilled from molecular sieves. CP grade carbon monoxide and
ethylene (Praxair) were used without purification.
(1-Bz-In d )Ni(P P h 3)(OTf), 3. The dark red solution of (1-
Bz-Ind)Ni(PPh3)Cl (250 mg, 0.445 mmol) in CH2Cl2 (25 mL)
was added to a stirred CH2Cl2 (15 mL) suspension of AgOTf
(170 mg, 0.662 mmol). The resultant mixture was stirred for
2 h at room temperature and filtered, and the filtrate was
evaporated to dryness. The residue was crystallized from C6H6/
hexane at room temperature to give the product as a red
powder (162 mg, 60%). 1H NMR (C6D6): 3.00 (m, H3), 3.62
2
4
(dd, J H--H ) 16.6 Hz, J P-H ) 4.8 Hz, -CH2-Ph), 3.34 (dd,
2J H-H ) 16.6 Hz, J P-H ) 4.8 Hz, -CH2-Ph), 5.90 (d, J H-H
)
4
3
3
3
7.4 Hz, H4), 6.09 (d, J H-H ) 1.8 Hz, H2), 6.74 (t, J H-H ) 7.9
Hz, H5), 7.00 (s, ArH), 7.08 (m, ArH), 7.42(d, J ) 6.6 Hz, ArH),
7.49 (m, ArH). The complete characterization of this compound
has been reported previously.20
(1-Et-In d )Ni(P P h 3)(OTf), 1. A CH2Cl2 solution (10 mL) of
CF3SO3H (33.0 µL, 0.37 mmol) was added dropwise to the
stirring CH2Cl2 solution (20 mL) of (1-Et-Ind)Ni(PPh3)(thienyl)
(201 mg, 0.37 mmol) at room temperature. The resulting red
mixture was stirred for 10 min and filtered, and the filtrate
evaporated to dryness. The residue was crystallized from
[(1-i-P r -In d )Ni(P P h 3)(CH3CN)]OTf, 4a . A CH2Cl2 solu-
tion (20 mL) of CH3CN (15.5 µL, 0.296 mmol) was added
dropwise to the stirring CH2Cl2 solution (10 mL) of (1-i-Pr-
Ind)Ni(PPh3)(OTf) (169 mg, 0.296 mmol) at room temperature.
The resulting yellow mixture was stirred for 15 min, then
evaporated to dryness. The orange oily residue was triturated
in 15 mL of Et2O at room temperature to give the product as
a yellow powder (90 mg, 50%). The dark yellow crystals
suitable for X-ray diffraction study were grown by vapor
diffusion of pentane into a CHCl3 solution of (1-i-Pr-Ind)Ni-
CH2Cl2/hexane at room temperature to give the product as a
3
red powder (120 mg, 52%). 1H NMR (C6D6): 1.29 (t, J H-H
)
7.3 Hz, -CH3), 1.74 (m, -CH2), 2.27 (m, -CH2), 3.04 (s, H3),
3
3
5.80 (d, J H-H ) 6.8 Hz, H4), 6.21 (d, J H-H ) 2.6 Hz, H2),
6.75 (t, 3J H-H ) 7.0 Hz, H5), 7.08 (t, 3J H-H ) 7.4 Hz, H6), 7.00
(m, PPh3), 7.38 (d, J H-H ) 8.0 Hz, H7), 7.51 (m, PPh3). 13C
3
NMR (CDCl3, 300 MHz): 11.00 (CH2CH3), 20.19 (CH2CH3),
60.39 (C3), 102.27 (C2), 114.05 (d, 2J P-C ) 11.3 Hz, C1), 117.66,
1
(PPh3)(CH3CN)(OTf) at room temperature. H NMR (CDCl3):
3
119.69, 127.38, 127.70, 128.18, 128.60 (d, J P-C ) 9.9 Hz,
3
3
1.38 (d, J H-H ) 6.8 Hz, -CH(CH3)2), 1.44 (d, J H-H ) 6.7 Hz,
-CH(CH3)2), 1.99 (s, CH3CN), 2.59 (m, CH(CH3)2), 4.18 (m,
m-PPh3), 129.38, 129.89 (d, J P-C ) 44.4 Hz, i-PPh3), 130.76
(s, p-PPh3), 133.88 (d, 2J P-C ) 11.8 Hz, o-PPh3). 31P{1H} NMR
(C6D6): 30.02 (s). 19F{1H} NMR (C6D6): -79.70 (s). FABMS
(m/z): 463 (M+ - OTf). Anal. Calcd for C30H26PNiO3SF3
(613.263): C, 58.76; H, 4.27, S, 5.23. Found: C, 58.60; H, 4.60,
S, 4.66.
3
3
H3), 6.08 (d, J H-H ) 7.8 Hz, H4), 6.36 (d, J H-H ) 3.1 Hz,
H2), 7.08 (t, J H-H ) 7.3 Hz, H5), 7.26-7.55 (ArH). 13C NMR
3
(CDCl3, 300 MHz): 14.05 (s, CH3CN), 20.22 (CH(CH3)2), 21.40
(d, 4J P-C ) 5.7 Hz, CH(CH3)2), 25.95 (s, CH(CH3)2), 71.66 (C3),
2
99.72 (C2), 117.56 (d, J P-C ) 9.8 Hz, C1), 118.46, 119.34,
123.66 (C3a), 125.65 (C7a), 128.30, 128.69, 129.20 (d, J P-C
3
(1-i-P r -In d )Ni(P P h 3)(OTf), 2. Meth od A. A CH2Cl2 solu-
tion (10 mL) of CF3SO3H (23 µL, 0.249 mmol) was added
dropwise to the stirring CH2Cl2 solution (20 mL) of (1-i-Pr-
Ind)Ni(PPh3)(thienyl) (140 mg, 0.249 mmol) at room temper-
ature. The resulting red mixture was stirred for 30 min and
filtered, and the filtrate evaporated to dryness. The residue
)
4
10.4, m-PPh3), 129.46, 130.84, 131.53 (d, J P-C ) 1.9 Hz,
p-PPh3), 133.43 (d, J P-C ) 11.9 Hz, o-PPh3) 133.88. 31P{1H}
2
NMR (CDCl3): 34.94 (s). 19F{1H} NMR (CDCl3): -80.62 (s).
IR (KBr): 2251 (w, CdN), 1543 (w), 1480 (m), 1437 (s), 1385
(m), 1260 (s), 1160 (s), 1123 (m), 1098 (m), 1948 (m), 1034 (s),
1002 (w), 749 (s), 725 (m), 695 (s), 660 (m), 639 (s), 543 (s),
532 (s), 511 (m), 495 (w). FAB-MS m/z (%): 518.1 [(1-i-Pr-Ind)-
Ni(PPh3)(CH3CN)]+ (11), 477.1 [(1-i-Pr-Ind)Ni(PPh3)]+ (100).
(29) Dubois, M.-A.; Wang, R.; Zargarian, D.; Tian, J .; Vollmerhaus,
R.; Li, Z.; Collins, S. Organometallics 2001, 20, 663.

5538 Organometallics, Vol. 21, No. 25, 2002
Wang et al.
Anal. Calcd for C33H31PNiO3SNF3‚1.3CHCl3 (823.533): C,
50.03; H, 3.95; S, 3.89; N, 1.70. Found: C, 49.99; H, 4.09; S,
3.93; N, 1.05.
-CH(CH3)2), 2.84 (m, -CH(CH3)2), 4.80 (m, H3), 6.14 (d, 3J H-H
3
) 7.6 Hz, H4), 6.27 (d, J H-H ) 3.0 Hz, H2), 7.19-7.56 (m,
ArH). 13C{1H} NMR (CDCl3, 300 MHz): 21.53 (CH(CH3)2),
22.04 (d, 4J P-C ) 4.2 Hz, CH(CH3)2), 27.18 (s, CH(CH3)2), 29.81
(CNC(CH3)3), 59.75 (CNC(CH3)3), 82.90 (C3), 99.51 (C2), 115.29
[(1-i-P r -In d )Ni(P P h 3)(CD3CN)]OTf, 4a ′. CD3CN (0.5 µL,
0.01 mmol) was added to the CDCl3 solution (0.5 mL) of (1-i-
Pr-Ind)Ni(PPh3)(OTf) (6 mg, 0.01 mmol) in an NMR tube. The
color of the solution changed from red to yellow after the
addition of CD3CN. 1H NMR (CDCl3): 1.39 (d, 3J H-H ) 6.9 Hz,
2
(d, J P-C ) 10.6 Hz, C1), 119.22, 120.48 (C3a), 121.99 (C7a),
3
129.12, 129.28, 129.65 (d, J P-C ) 10.8 Hz, m-PPh3), 129.81,
4
2
130.45, 132.31 (d, J P-C ) 2.4 Hz, p-PPh3), 133.81 (d, J P-C
)
11.3 Hz, o-PPh3). 31P{1H} NMR (CDCl3): 38.11 (s). 19F{1H}
NMR (CDCl3): -79.47 (s). IR (KBr): 2196 (s, CdN), 1630 (w),
1479 (m), 1437 (m), 1385 (s), 1272 (s), 1223 (m), 1185 (w), 1148
(s), 1121 (w), 1098 (m), 1032 (s), 999 (w), 765 (m), 754 (m),
697 (s), 638 (s), 533 (s), 510 (s). Anal. Calcd for C36H37PNiO3-
SNF3 (710.422): C, 60.86; H, 5.25; S, 4.51; N, 1.97. Found: C,
60.95; H, 5.38; S, 4.22; N, 2.07.
3
-CH(CH3)2), 1.44 (d, J H-H ) 6.6 Hz, -CH(CH3)2), 2.59 (m,
CH(CH3)2), 4.17 (m, H3), 6.08 (d, 3J H-H ) 8.0 Hz, H4), 6.36 (d,
3
3J H-H ) 2.7 Hz, H2), 7.08 (t, J H-H ) 7.3 Hz, H5), 7.26-7.55
(m, ArH). 31P{1H} NMR (CDCl3): 34.97 (s). 19F{1H} NMR
(CDCl3): -80.81 (s).
[(1-i-P r -In d )Ni(P P h 3)(CO)]OTf, 6a . Bubbling CO through
a stirred C6H6 solution (20 mL) of (1-i-Pr-Ind)Ni(PPh3)(OTf)
(150 mg, 0.239 mmol) at room temperature resulted in the
precipitation of a yellow solid, which was filtered and washed
[(1-i-P r -In d )Ni(P P h 3)2](OTf), 9a . Dropwise addition of a
C6H6 solution (20 mL) of PPh3 (64 mg, 0.246 mmol) to the
stirred C6H6 solution (10 mL) of (1-i-Pr-Ind)Ni(PPh3)(OTf) (150
mg, 0.239 mmol) at room temperature resulted in the precipi-
tation of a dark yellow solid. Recrystallization of this solid from
CH2Cl2/hexane gave the desired product (162 mg, 76%). 1H
1
twice with hexane to give a yellow powder (98 mg, 63%). H
3
NMR (CDCl3): 1.43 (d, J H-H ) 6.7 Hz, -CH(CH3)2, 1.58 (d,
3J H-H ) 6.6 Hz, -CH(CH3)2), 3.06 (m, -CH(CH3)2), 5.53 (m,
3
3
H3), 6.11 (d, J H-H ) 8.0 Hz, H4), 6.65 (d, J H-H ) 3.2 Hz,
H2), 7.26 (m, ArH), 7.53 (m, ArH). 13C{1H} NMR (CDCl3, 400
MHz): 21.50 (CH(CH3)2), 22.93 (d, 4J P-C ) 6.4 Hz, CH(CH3)2),
3
NMR (CDCl3): 0.85 (d, J H-H ) 6.3 Hz, -CH(CH3)2), 1.14 (d,
3J H-H ) 6.2 Hz, -CH(CH3)2), 0.78 (m, -CH(CH3)2), 5.13 (m,
H3), 5.54 (d, J H-H ) 7.7 Hz, ArH), 6.60 (d, J H-H ) 7.9 Hz, ArH),
6.74 (d, J H-H ) 3.2 Hz, ArH), 7.00 (m, ArH) 7.13-7.60 (m,
ArH). 31P{1H} NMR (CDCl3): 34.97 (d, 2J p-p ) 25.4 Hz), 29.78
2
27.22 (s, CH(CH3)2), 91.77 (d, J P-C ) 3.2 Hz, C3), 101.52 (d,
2J P-C ) 3.2 Hz, C2), 117.84 (C3a), 119.09 (C7a), 119.83, 120.07,
120.25, 121.24, 121.40 (d, 2J P-C ) 10.6 Hz, C1), 129.66 (d, 3J P-C
) 11.2 Hz, m-PPh3), 130.83 (d, 1J P-C ) 62.6 Hz, i-PPh3), 132.41
(d, 4J P-C ) 2.4 Hz, p-PPh3), 133.46 (d, 2J P-C ) 11.2 Hz, o-PPh3),
189.54 (d, 2J P-C ) 16.8 Hz, CO). 31P{1H} NMR (CDCl3): 36.08
(s). 19F{1H} NMR (CDCl3): -79.57 (s). IR (KBr): 2089 (s), 1995
(m), 1638 (m), 1479 (m), 1460 (w), 1438 (s), 1385 (m), 1267 (s),
1173 (s), 1159 (s), 1121 (m), 1095 (m), 1045 (m), 747 (s), 754
(m), 725 (m), 696 (s), 637 (s), 544 (m), 531 (m), 516 (m). FAB-
MS m/z (%): 505.1 [(1-i-Pr-Ind)Ni(PPh3)(CO)]+ (100), 477.1 [(1-
i-Pr-Ind)Ni(PPh3)]+ (98). Anal. Calcd for C32H28PNiO4SF3
(655.30): C, 58.65; H, 4.31; S, 4.89. Found: C, 58.16; H, 3.84;
S, 4.90.
2
(d, J p-p ) 25.4 Hz). 19F{1H} NMR (CDCl3): -79.37 (s). FAB-
MS m/z (%): 739.2 [(1-i-Pr-Ind)Ni(PPh3)2]+ (76), 477.2 [(1-i-
Pr-Ind)Ni(PPh3)]+ (100), 582.1 [Ni(PPh3)2]+ (34).
Th e Rem a in in g Ad d u cts. In a number of cases, the
substitution of OTf in 2 or 3 by L was monitored spectroscopi-
cally, without isolating the resulting adducts. These reactions
were carried out by adding 1 equiv of L (except for CO, which
was bubbled through for 2-3 min) to a 0.5 mL CDCl3 solution
of 2 or 3 (ca. 0.015 mmol) in an NMR tube. The NMR spectra
of these samples were then measured at room temperature.
The data are given below.
[(1-Bz-In d )Ni(P P h 3)(CH3CN)]OTf, 4b. 1H NMR (CDCl3):
(1-i-P r -In d )Ni(P P h 3)(P y)(OTf), 7a . A C6H6 solution (20
mL) of pyridine (19.3 µL, 0.239 mmol) was added dropwise to
the stirred C6H6 solution (10 mL) of (1-i-Pr-Ind)Ni(PPh3)(OTf)
(150 mg, 0.239 mmol) at room temperature. The resulting
orange mixture was stirred for 5 min, then evaporated to
dryness. The orange oily residue was triturated in 15 mL of
Et2O at room temperature to give the product as a yellow
powder (110 mg, 65%). 1H NMR (CDCl3): 1.12 (d, 3J H-H ) 6.5
2
4
1.96 (b, CH3CN), 3.47 (dd, J H-H ) 14.3 Hz, J P-H ) 2.5 Hz,
2
4
-CH2-Ph), 3.58 (dd, J H-H ) 14.3 Hz, J P-H ) 2.5 Hz, -CH2-
3
3
Ph), 4.16 (m, H3), 6.04 (d, J H-H ) 7.7 Hz, H4), 6.42 (d, J H-H
3
) 2.5 Hz, H2), 7.06 (t, J H-H ) 7.4 Hz), 7.34-7.49 (m, ArH).
31P{1H} NMR (CDCl3): 34.93 (s). 19F{1H} NMR (CDCl3):
-79.33 (s).
[(1-i-P r -In d )Ni(P P h 3)(P h CN)]OTf, 5a . 1H NMR (CDCl3):
3
3
3
1.29 (d, J H-H ) 6.7 Hz, -CH(CH3)2), 1.38 (d, J H-H ) 6.6 Hz,
-CH(CH3)2), 2.45 (m, -CH(CH3)2),), 4.21 (m, H3), 5.95 (d,
Hz, -CH(CH3)2), 1.17 (d, J H-H ) 6.8 Hz, -CH(CH3)2), 1.44
3
(m, -CH(CH3)2), 4.21 (m, H3), 6.18 (d, J H-H ) 7.6 Hz, H4),
3J H-H ) 6.6 Hz, H4), 6.37 (d, J H-H ) 2.9 Hz, H2), 6.87-7.38
3
6.75 (d, 3J H-H ) 2.6 Hz, H2), 7.09-7.87 (m, ArH), 8.60 (s, PyH).
31P{1H} NMR (CDCl3): 32.84 (s). 19F{1H} NMR (CDCl3):
-79.45 (s). 13C{1H} NMR (CDCl3, 300 MHz): 19.76 (CH(CH3)2),
21.23 (CH(CH3)2), 25.74 (CH(CH3)2), 68.32 (C3), 101.39 (C2),
(m, ArH). 31P{1H} NMR (CDCl3): 35.21 (s). 19F{1H} NMR
(CDCl3): -79.61 (s).
[(1-Bz-In d )Ni(P P h 3)(P h CN)]OTf, 5b. 1H NMR (CDCl3):
2
2
2
3.45 (d, J H-H ) 15.4 Hz, -CH2-Ph), 3.75 (d, J H-H ) 15.4 Hz,
115.28 (d, J P-C ) 10.6 Hz, C1), 117.72 (C3a), 119.57 (C7a),
3
1
-CH2-Ph), 4.30 (m, H3), 6.05 (d, J H-H ) 7.8 Hz, H4), 6.65 (d,
125.16, 126.00, 128.07, 128.75 (d, J P-C ) 45.39 Hz, i-PPh3),
3J H-H ) 1.8 Hz, H2), 7.11 (t, J H-H ) 7.4 Hz), 7.26-7.64 (m,
3
3
4
129.16 (d, J P-C ) 10.2 Hz, m-PPh3), 130.80, 131.24 (d, J P-C
) 2.3 Hz, p-PPh3), 133.21 (d, 2J P-C ) 11.2 Hz, o-PPh3), 133.84,
138.57 (b, Py), 152.19 (Py). FAB-MS m/z (%): 556.2 [(1-i-Pr-
Ind)Ni(PPh3)(Py)]+ (76), 477.1 [(1-i-Pr-Ind)Ni(PPh3)]+ (100),
399.1 [Ni(PPh3)(Py)]+ (16). Anal. Calcd for C36H33PNiO3SNF3
(706.391): C, 61.21; H, 4.71; S, 4.54; N, 1.98. Found: C, 60.84;
H, 4.96; S, 4.00; N, 1.96.
ArH). 31P{1H} NMR (CDCl3): 35.25 (s). 19F{1H} NMR (CDCl3):
-79.41 (s).
[(1-Bz-In d )Ni(P P h 3)(CO)]OTf, 6b. 1H NMR (CDCl3): 3.92
(d, 2J H-H ) 14.2 Hz, -CH2-Ph), 4.35 (d, 2J H-H ) 14.2 Hz, -CH2-
3
Ph), 5.35 (m, H3), 5.99 (d, J H-H ) 7.4 Hz, H4), 6.90-7.68 (m,
ArH). 31P{1H} NMR (CDCl3): 36.23 (s). 19F{1H} NMR (CDCl3):
-79.48 (s).
(1-i-P r -In d )Ni(P P h 3)(CNC(CH3)3)(OTf), 8a . A C6H6 solu-
tion (20 mL) of CNC(CH3)3 (29.4 µL, 0.260 mmol) was added
dropwise to the stirred C6H6 solution (10 mL) of (1-i-Pr-Ind)-
Ni(PPh3)(OTf) (200 mg, 0.319 mmol) at room temperature.
After 5 min, the resulting orange mixture was concentrated
to precipitate the desired product, which was filtered and
washed twice with pentane to afford a yellow powder (100 mg,
54%). Crystals suitable for X-ray diffraction studies were
grown by the slow (room temperature) evaporation of a
toluene/CDCl3 mixture. 1H NMR (CDCl3): 1.01 (s, CNC(CH3)3),
[(1-Bz-In d )Ni(P P h 3)(P y)]OTf), 7b. 1H NMR (CDCl3): 2.31
(dd, 2J H-H ) 15.0 Hz, 4J P-H ) 3.0 Hz, -CH2-Ph), 3.29 (dd, 2J H-H
4
) 15.0 Hz, J P-H ) 2.2 Hz, -CH2-Ph), 4.21 (m, H3), 6.25 (d,
3J H-H ) 7.8 Hz, H4), 7.12-8.62 (m, ArH). 31P{1H} NMR
(CDCl3): 31.98(s). 19F{1H} NMR (CDCl3): -79.45 (s).
[(1-Bz-In d )Ni(P P h 3)(CNC(CH3)3)]OTf, 8b. 31P{1H} NMR
(CDCl3): 38.11 (s). 19F{1H} NMR (CDCl3): -79.47(s).
1
[(1-Bz-In d )Ni(P P h 3)2]OTf, 9b. H NMR (CDCl3): 2.27 (d,
2J H-H ) 14.3 Hz, -CH2-Ph), 3.03 (d, J H-H ) 14.3 Hz, -CH2-
2
3
3
1.40 (d, J H-H ) 6.9 Hz, -CH(CH3)2), 1.50 (d, J H-H ) 6.6 Hz,
Ph), 5.04 (m, H3), 6.00 (d, J H-H ) 7.2 Hz, ArH), 6.28 (d, J H-H

Nickel-Triflate Complexes
Organometallics, Vol. 21, No. 25, 2002 5539
) 7.1 Hz, ArH), 6.92 (d, J H-H ) 7.2 Hz, ArH), 7.08-7.43 (m,
ArH). 31P{1H} NMR (CDCl3): 35.17 (d, 2J p-p ) 25.5 Hz), 32.12
P h (Me)SiH2. To a C6D6 solution of 2 (10 mg, 0.016 mmol,
0.032 M) was added Ph(Me)SiH2 (0.020 mL, 0.14 mmol) and
the sample shaken to ensure mixing. A red to brown color
2
(d, J p-p ) 25.5 Hz). 19F{1H} NMR (CDCl3): -79.27 (s).
[(1-i-P r -In d )Ni(P P h 3)(P Me3)]OTf, 10a . 31P{1H} NMR
1
change was observed. Analysis by H NMR showed that only
2
2
(CDCl3): 41.69 (d, J p-p ) 42.0 Hz), -10.44 (d, J p-p ) 42.0
a small amount of Ph(Me)SiH2 (<5 equiv) had been converted
2
2
3
Hz); -8,71 (d, J p-p ) 42.0 Hz), 15.01 (d, J p-p ) 42.0 Hz).
to the dimer (δ 1.20 (d, J H-H ) 6.9 Hz, Me), 4.45 (b, SiH)).
[(1-Bz-In d )Ni(P P h 3)(P Me3)]OTf, 10b. 31P{1H} NMR
X-r a y Diffr a ction Stu d ies of 2, 4a , a n d 8a . Dark red
crystals of 2 were grown from a CH2Cl2/hexane solution at -20
°C; the crystals of 2 did not decompose after exposure to air
for 21 days. Dark yellow crystals of 4a were grown by vapor
diffusion of pentane into a CHCl3 solution at room tempera-
ture; complex 4a cocrystallized with one molecule of CHCl3 in
each unit cell. Dark yellow crystals of 8a suitable for X-ray
diffraction study were grown by vapor diffusion of pentane into
a CHCl3 solution at room temperature. The crystallographic
data (Table 1) were collected on a Bruker AXS SMART 2K
diffractometer with graphite-monochromated Cu KR radiation
at 293(2) K using SMART.30 Cell refinement and data reduc-
tion were done using SAINT.31 The structures were solved by
direct methods using SHELXS9732 and difmap synthesis using
SHELXL96;33 refinements were done on F2 by full-matrix least
squares. The OTf group and CHCl3 molecule in 4a are
disordered. Similarly, the OTf anion and the three methyl
groups on the isocyanide ligand in 8a are disordered, too.
Complete crystallographic data for these three structures are
included in the Supporting Information.
2
2
(CDCl3): 41.27 (d, J p-p ) 42.0 Hz), -10.26 (d, J p-p ) 42.0
2
2
Hz); 40.86 (d, J p-p ) 43.3 Hz), -17.03 (d, J p-p ) 43.3 Hz).
19F{1H} NMR (CDCl3): -79.52 (s).
Rea ction of 2 w ith 1-Hexen e. NMR spectroscopy was
used to monitor the reaction of 1-hexene (0.1 mL, 0.80 mmol,
1.6 M in CDCl3) and 2 (10 mg, 0.016 mmol, 0.032 M in CDCl3).
The 13C{1H} NMR spectra indicated a slow isomerization of
1-hexene (ca. 24 h) to mostly E-2-hexene (13.6, 17.9, 22.7, 34.8,
124.7, and 131.4 ppm) and another minor isomer (12.4, 13.7,
25.6, 28.9, 123.8, and 130.6 ppm). The GC/MS analysis of the
NMR mixture or that of a CH2Cl2 solution of 1-hexene (0.2
mL, 1.6 mmol) and 2 (20 mg, 0.032 mmol) showed the presence
of hexenes and traces of 1,3-(hexenyl, i-propyl)-indene (M•+
)
240; M•+ - 15 (CH3); M•+ - 29 (CH2CH3); M•+ - 43 (Pr or i-Pr);
M•+ - 57 (Bu); etc.).
Dim er iza tion of Eth ylen e Ca ta lyzed by 2. A CDCl3
solution of 2 (30 mg, 0.048 mmol, in 2 mL) was saturated with
ethylene (ca. 5 min) prior to analysis by NMR and GC/MS. 1H
3
NMR (CDCl3): 1.61 (d, J H-H ) 5.0, CH3 of Z-butene), 1.64
(dd, 3J H-H ) 5.0, 4J H-H ) 1.2, CH3 of E-butene), 5.44 (m, vinylic
H for both Z- and E-butenes). The GC/Ms showed both butenes
(predominant) and another species that displayed the frag-
mentation pattern consistent with (isopropyl, vinyl)indene:
Ack n ow led gm en t. We are grateful to the NSERC
of Canada, the FCAR of Que´bec, and Universite´ de
Montre´al for financial support, to Prof. He´le`ne Lebel and
Vale´rie Paquet for GC/MS analyses, and to J ake Dal-
phond and Dr. H. Sleiman for GPC.
M•+ (184, C14H16), M•+ - 15 (C13H13), M•+ - 43 (C11H9), M•+
-
56 (C10H8), M•+ - 69 (C9H7).
P olym er iza tion of P h CCH. A mixture of Ph-CC-H (1.08
mL, 9.6 mmol) and 2 (30 mg, 0.048 mmol) was stirred for 24
h at 50 °C. Addition of MeOH to the mixture gave an oily
yellow solid, which was filtered and recrystallized from THF/
MeOH to give a yellow powder (ca. 5% yield). Similar results
were obtained when the reaction was carried out with the same
Ni:substrate ratio but in THF. Analysis of the product obtained
Su p p or tin g In for m a tion Ava ila ble: Complete details on
the X-ray analyses of 2, 4a , and 8a , including tables of bond
distances and angles, anisotropic thermal parameters, and
hydrogen atom coordinates. These materials are available free
of charge via the Internet at http://pubs.acs.org.
from the neat reaction by GPC gave the following data: Mw
)
8189, Mn ) 4418, Mw/Mn ) 1.85. The 1H NMR spectrum of
this solid showed a broad, featureless signal at ca. 6.5-7.8
ppm.
OM020558A
Dim er iza tion of Sila n es Ca ta lyzed by 2. P h SiH3. To a
C6D6 solution of 2 (10 mg, 0.016 mmol, 0.032 M) was added
PhSiH3 (0.20 mL, 1.6 mmol) and the sample shaken to ensure
mixing. A red to brown color change was observed. Analysis
(30) SMART, Release 5.059; Bruker Molecular Analysis Research
Tool; Bruker AXS Inc.: Madison, WI, 53719-1173, 1999.
(31) SAINT, Release 6.06; Integration Software for Single-Crystal
Data; Bruker AXS Inc.: Madison, WI, 53719-1173, 1999.
(32) Sheldrick, G. M. SHELXS, Program for the Solution of Crystal
Structures; University of Goettingen: Germany, 1997.
1
by H NMR showed that only a small amount of PhSiH3 (<5
equiv) had been converted to the dimer (δ 4.48, b, PhSiH2).
Analysis by 31P{1H} NMR showed the presence of a peak at
40.18 ppm.
(33) Sheldrick, G. M. SHELXL, Program for the Refinement of
Crystal Structures; University of Goettingen: Germany, 1996.