Structure and reactivity of the cationic nickel compound [(η3:η1-Ind(CH2)2 NMe2)Ni(PPh3)][BPh4]

Article abstract of DOI:10.1021/om010200z

The solid-state structure of the first nickel compound containing a chelating amino-indenyl ligand, [(η³:η¹-Ind(CH₂)₂ NMe₂)Ni(PPh₃)][BPh₄] (2), has been resolved and confirms the chelation of the amine tether to the nickel center. Complex 2 acts as a precatalyst for the oligomerization of norbornene, the dimerization of phenylsilane, and the polymerization of styrene. The results of these catalytic reactions are qualitatively different from those catalyzed by the cationic species generated in situ from the precursor complex (η³:η⁰-Ind(CH₂)₂ NMe₂)Ni(PPh₃)Cl (1). Phosphines displace the amine tether in 2 to give the bis-(phosphine) cations [(η³:η⁰-Ind(CH₂)₂ NMe₂)Ni(Ph₂PCH₂CH₂ PPh₂)]⁺ (3) and [(η³:η⁰- Ind(CH₂)₂NMe₂)Ni(PPh₃) (PR₃)]⁺ (4, R = Ph; 5, R = Me), whereas LiI reacts to form the neutral compound [(η³:η⁰- Ind(CH₂)₂NMe₂)Ni(PPh₃)I]· LiBPh₄ (7). displacement of the amine tether by pyridine and its methyl-substituted derivatives leads to an equilibrium between 2 and [(η³:η⁰-Ind(CH₂)₂ NMe₂)Ni(PPh₃)L]⁺ (6) with K_eq values of 9 (6a, L = pyridine), 2.0 (6b, L = 2-picoline), 23 (6c, L = 3-picoline), 33 (6d, L = 4-picoline), and 16 (6e, L = 3,5-lutidine).

Full text of DOI:10.1021/om010200z

Organometallics 2001, 20, 3811-3817
3811
Str u ctu r e a n d Rea ctivity of th e Ca tion ic Nick el
Com p ou n d [(η3:η1-In d (CH2)2NMe2)Ni(P P h 3)][BP h 4]
Laurent F. Groux and Davit Zargarian*
De´partement de chimie, Universite´ de Montre´al, Montre´al, Que´bec, Canada H3C 3J 7
Received March 13, 2001
The solid-state structure of the first nickel compound containing a chelating amino-indenyl
ligand, [(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4] (2), has been resolved and confirms the
chelation of the amine tether to the nickel center. Complex 2 acts as a precatalyst for the
oligomerization of norbornene, the dimerization of phenylsilane, and the polymerization of
styrene. The results of these catalytic reactions are qualitatively different from those
catalyzed by the cationic species generated in situ from the precursor complex (η3:η0-
Ind(CH2)2NMe2)Ni(PPh3)Cl (1). Phosphines displace the amine tether in 2 to give the bis-
(phosphine) cations [(η3:η0-Ind(CH2)2NMe2)Ni(Ph2PCH2CH2PPh2)]+ (3) and [(η3:η0-Ind(CH2)2-
NMe2)Ni(PPh3)(PR3)]+ (4, R ) Ph; 5, R ) Me), whereas LiI reacts to form the neutral
compound [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)I]‚LiBPh4 (7). The displacement of the amine tether
by pyridine and its methyl-substituted derivatives leads to an equilibrium between 2 and
[(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)L]+ (6) with Keq values of 9 (6a , L ) pyridine), 2.0 (6b, L )
2-picoline), 23 (6c, L) 3-picoline), 33 (6d , L ) 4-picoline), and 16 (6e, L ) 3,5-lutidine).
Sch em e 1. Rea ctivity of [(1-MeIn d )Ni(P P h 3)]+
In tr od u ction
During the course of our investigations1 into the
chemistry of the complexes (Ind)(PPh3)Ni-X (Ind )
indenyl and its substituted derivatives; X ) halide,
alkyl, alkynyl, imidate, thiolate, etc.), it was found that
the in situ generated cationic species [(Ind)(PPh3)Ni]+
can catalyze a number of reactions, including the
dimerization of ethylene to butenes,1a,e the dehydroge-
native oligomerization of PhSiH3 to (PhSiH)n,1d the
oligomerization of styrene, the polymerization of nor-
bornene, and the copolymerization of styrene and nor-
bornene. In situ generated [(Ind)(PPh3)Ni]+ also reacts
with phosphines or donor solvents such as MeCN to
form the adducts [(Ind)(PPh3)NiL]+; indeed, the elec-
trophilicity of the “naked” cation is such that in the
absence of added ligand and donor solvents it undergoes
a redistribution reaction to form [(Ind)Ni(PPh3)2]+,
which is catalytically inert (Scheme 1). The presence of
this deactivation pathway has hindered further inves-
tigations into the structure and reactivities of these
highly electrophilic cations.
while maintaining catalytic activity. Aminoindenyl
ligands were chosen for this purpose because it was
anticipated that (a) the proximity of the amine-func-
tionalized tether to the nickel center would facilitate
NfNi coordination and prevent the formation of the
inert bis(phopshine) species and (b) the lower affinity
of the amine moiety, relative to phosphines, for coordi-
nation to nickel3 would not shut down the catalytic
activity. In an earlier report,4 we described the prepara-
tion and complete characterization of the precursor
complex (η3:η0-Ind(CH2)2NMe2)(PPh3)Ni-Cl (1) and pre-
sented spectroscopic evidence for the formation of the
In an effort to circumvent this deactivation of the
unstable cations [(Ind)(PR3)Ni]+, we set out to prepare
analogous complexes bearing hemilabile coordinating
moieties2 which might stabilize the cationic intermedi-
ates sufficiently to allow isolation and characterization
(2) Recent reviews on side-chain-functionalized cyclopentadienyl
compounds: (a) J utzi, P.; Redeker, T. Eur. J . Inorg. Chem. 1998, 663.
(b) Mu¨ller, C.; Vos, D.; J utzi, P. J . Organomet. Chem. 2000, 600, 127.
(3) The generally stronger binding of phosphines vs amines to low-
valent late transition metals is well-documented: (a) 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 241, and references therein. (b) Li, M. P.; Drago,
R. S.; Pribula, A. J . J . Am. Chem. Soc. 1977, 99, 6900. (c) de Graaf,
W.; Boersma, J .; Smeets, W. J . J .; Spek, A. L.; van Koten, G.
Organometallics 1989, 8, 2907. (d) Wang, L.; Wang, C.; Bau, R.; Flood,
T. C. Organometallics 1996, 15, 491. (e) Widenhoefer, R. A.; Buchwald,
S. L. Organometallics 1996, 15, 2755. (f) Widenhoefer, R. A.; Buchwald,
S. L. Organometallics 1996, 15, 3534. (g) Pfeiffer, J .; Kickelbick, G.;
Schubert, U. Organometallics 2000, 19, 62.
(1) (a) Dubois, M.-A.; Wang, R.; Zargarian, D.; Tian, J .; Vollmerhaus,
R.; Li, Z.; Collins, S. Organometallics 2001, 20, 663. (b) Wang, R.;
Be´langer-Garie´py, F.; Zargarian, D. Organometallics 1999, 18, 5548.
(c) Dubuc, I.; Dubois, M.-A.; Be´langer-Garie´py, F.; Zargarian, D.
Organometallics 1999, 18, 30. (d) Fontaine, F.-G.; Kadkhodazadeh, T.;
Zargarian, D. J . Chem. Soc., Chem. Commun. 1998, 1253. (e) Voll-
merhaus, R.; Be´langer-Garie´py, F.; Zargarian, D. Organometallics
1997, 16, 4762. (f) Huber, T. A.; Bayrakdarian, M.; Dion, S.; Dubuc,
I.; Be´langer-Garie´py, F.; Zargarian, D. Organometallics 1997, 16, 5811.
(g) Bayrakdarian, M.; Davis, M. J .; Reber, C.; Zargarian, D. Can. J .
Chem. 1996, 74, 2194. (h) Huber, T. A.; Be´langer-Garie´py, F.; Zarga-
rian, D. Organometallics 1995, 14, 4997.
(4) Groux, L. F.; Be´langer-Garie´py, F.; Zargarian, D.; Vollmerhaus,
R. Organometallics 2000, 19, 1507.
10.1021/om010200z CCC: $20.00 © 2001 American Chemical Society
Publication on Web 07/26/2001

3812 Organometallics, Vol. 20, No. 17, 2001
Groux and Zargarian
Sch em e 2. P r ep a r a tion of
[(η3:η1-In d (CH2)2NMe2)Ni(P P h 3)][BP h 4]
cationic complex [(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4]
(2). The present paper reports the structural charac-
terization of 2 and describes the ligand substitution
reactions and catalysis arising from the displacement
of the amine tether by various ligands.
Resu lts a n d Discu ssion
Complex 2 can be prepared in ca. 60% yield by
abstracting Cl- from 1 in CH2Cl2 (Scheme 2).4 The
31P{1H} NMR spectrum of the product showed that the
signal for the precursor (ca. 31 ppm) was replaced by a
new singlet resonance (ca. 29 ppm). The absence of an
AB resonance which is characteristic of the inequivalent
P nuclei in the bis(phosphine) cations [(1-R-Ind)Ni-
(PPh3)2]+ 1e indicated that the formation of undesired
byproducts of this type had been circumvented. In
addition, the appearance of two different N-Me signals
F igu r e 1. ORTEP view of complex 2. The counterion and
hydrogen atoms are omitted for clarity. Thermal ellipsoids
are shown at 40% probability. Selected bond distances (Å)
and angles (deg): Ni-P ) 2.1971(11), Ni-N ) 2.005(2),
Ni-C(1) ) 2.040(2), Ni-C(2) ) 2.056(3), Ni-C(3) )
2.078(3), Ni-C(3A) ) 2.327(3), Ni-C(7A) ) 2.314(2), C(1)-
C(2) ) 1.412(4), C(2)-C(3) ) 1.399(4), C(3)-C(3A) )
1.455(3), C(3A)-C(7A) ) 1.420(3), C(1)-C(7A) ) 1.463(3),
∆(M-C) ) 0.26,6 P-Ni-N ) 107.52(7), C(3)-Ni-N )
149.55(10), C(3)-Ni-P ) 101.79(8), C(1)-Ni-N ) 84.86(11),
C(1)-Ni-P ) 166.49(8), C(1)-Ni-C(3) ) 66.97(11). C3A
and C7A refer to the atoms shared by the five- and six-
membered rings of Ind.
1
in the H NMR spectrum of the product was consistent
with the coordination of the NMe2 moiety to the nickel
center, which is dissymmetric (2 has C1 symmetry), and
so the Me2NfNi coordination renders the Me groups
diastereotopic. The structural characterization of 2,
which is air stable in the solid state, was completed by
an X-ray analysis carried out on a single crystal grown
by the slow vapor diffusion of Et2O into a CH2Cl2
solution of this compound. An ORTEP diagram of 2 is
shown in Figure 1, along with selected structural
parameters. Crystal data and data collection and struc-
ture refinement details are given in Table 1. The main
features of the structure are described below.
The Ni-N distance of 2.005(2) Å in 2 is within the
expected range for NiII-NR3 bonds,5 whereas the Ni-P
distance is somewhat longer (by ca. 12σ) than the
corresponding distance in the neutral Ni-Cl precursor
1;4 this is likely the result of the steric hindrance caused
by the amine moiety. The strain imposed by the chela-
tion of the tether is reflected in the small C1-Ni-N
angle of 84.81(10)° (compared to ca. 96° for the C1-
Ni-Cl angle in 1) and the large P-Ni-N angle of
107.52(7)° (compared to ca. 98° for the P-Ni-Cl angle
in 1). The chelation can also be invoked to explain why
Ni-C1 is shorter than Ni-C3 despite the greater
relative trans influence of PPh3, which would otherwise
be expected to result in a longer Ni-C1 bond.
Ta ble 1. Cr ysta l Da ta a n d Da ta Collection a n d
Str u ctu r e Refin em en t Deta ils of 2
formula
mol wt
C55H51BNPNi
826.46
cryst color
cryst habit
cryst dimens, mm
symmetry
space group
a, Å
dark red
block
0.36 × 0.28 × 0.16
triclinic
P1h
11.161(6)
14.119(5)
15.115(9)
82.69(4)
b, Å
c, Å
R, deg
â, deg
79.86(6)
72.65(4)
2231(2)
γ, deg
V, Å3
Z
2
D(calcd), g cm-3
diffractometer
temp, K
λ(Cu KR), Å
µ, mm-1
scan type
1.2303
Nonius CAD-4
293(2)
1.540 56
1.240
ω/2θ
69.80
-13 e h e 13
-17 e k e 17
-18 e l e 18
6134
θ
max, deg
hkl range
no. of rflns used (I > 2σ(I))
abs cor
integration ABSORB19
0.6601, 0.8336
0.0386, 0.0942
0.898
The coordination of the indenyl moiety in 2 is inter-
mediate between η5 and η3, as inferred from the
significantly shorter Ni-C1, Ni-C2, and Ni-C3 dis-
tances compared to Ni-C3A and Ni-C7A. The degree
of such “slippage” away from the idealized η5 coordina-
tion is often measured by the parameter ∆(M-C) )
1/2[(M-C3A + M-C7A) - (M-C1 + M-C3)],6 which is
T (min, max)
R(F2 > 2σ(F2)), Rw(F2)
GOF
0.26 Å for 2. Interestingly, this degree of slippage is
similar to those of the neutral compounds (1-Me-Ind)-
(PPh3)Ni-X (0.25 Å for X ) Cl1f and 0.27 Å for X )
phthalimidate1c) but larger than the ∆(M-C) of cationic
analogues such as [(1-Me-Ind)Ni(PPh3)(PMe3)]+ (0.19
(5) On the basis of 1290 crystal structures of compounds containing
a Ni-NR3 bond (Cambridge Structural Database, version 5.18; Cam-
bridge University: Cambridge, England; accessed Nov 2000), the
average and median Ni-NR3 bond lengths are 2.087 and 2.100 Å,
respectively.
(6) (a) Baker, R. T.; Tulip, T. H. Organometallics 1986, 5, 839. (b)
Westcott, S. A.; Kakkar, A.; Stringer, G.; Taylor, N. J .; Marder, T. B.
J . Organomet. Chem. 1990, 394, 777.

[(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4]
Organometallics, Vol. 20, No. 17, 2001 3813
Ta ble 2. P olym er iza tion Exp er im en ts w ith
(η3:η0-In d (CH2)2NMe2)Ni(P P h 3)Cl (1) a n d
[(η3:η1-In d (CH2)2NMe2)Ni(P P h 3)][BP h 4] (2)
with Mw ) 77 338 and Mw/Mn ) 3.15, and turn-
1
over numbers of ca. 300-400 (run 2, Table 2). The H
NMR spectra (CDCl3) of these polymers show charac-
teristically broad signals at 7.05, 6.59, 1.85, and 1.45
ppm, while the 13C{1H} NMR spectra show broad
signals at 145.5 (ipso-C), 128.1 (o- and m-C), 125.5 (p-
C), and 43.7 and 40.5 ppm. The analogous reaction with
norbornene also requires heating to 80 °C but gives only
oligomeric materials (Mw ) 763; Mw/Mn ) 1.1) with
turnover numbers of 20-40 (runs 5 and 6, Table 2).
Attempts at copolymerizing these two olefins were
unsuccessful and gave instead polystyrenes only (runs
7-9, Table 2).
amt of monomer,
equiv
sty-
nor-
T
time
Mw/
run catalyst rene bornene (°C) (days) Mw
Mn TON
1
2
3
4
5
6
7
8
9
2
2
2000
2000
20
80
80
80
20
80
50
50
50
20
60
20
60
50
50
50
7
2
2
2
4
4
2
2
2
2
2
2
2
2
2
2
0
3.2 364
1.9 980
1.2 860
0
77338
12726
65980
a
2/AgBF4 2000
2/AgCla
2000
2
2
2
2
2
1000
800
100
200
300
763
1.1
35
19
9
300
200
100
18320 12.0
3071
570
4.5
1.4
1.3 1650
1.5 1570
270
It is noteworthy that the outcomes of the reactions of
styrene and norbornene with 2 are quite different from
the analogous reactions catalyzed by the in situ gener-
ated species [IndNi(PPh3)]+. For instance, catalysis by
[IndNi(PPh3)]+ proceeds at room temperature to give
insoluble norbornene polymers and soluble styrene
trimers and tertramers.10 Moreover, the latter system
can catalyze the formation of various styrene-nor-
bornene copolymers. To our surprise, the polymerization
reactions catalyzed by the cationic species generated in
situ by reacting the precursor complex (η3:η0-Ind(CH2)2-
NMe2)(PPh3)Ni-Cl (1) with AgBF4 gave results which
were similar to those obtained from in situ generated
[IndNi(PPh3)]+ but very different from the results of the
polymerizations catalyzed by preformed 2 (compare runs
1 and 2 to runs 10 and 11, runs 5 and 6 to 12 and 13,
and runs 7-9 to 14-16; Table 2). We suspect that the
difference in the reactivities of 2 and the in situ
generated [IndNi(PPh3)]+ results from the influence of
the amine tether on the course of the reaction. Thus,
when 2 is generated in situ (from 1 and AgBF4), it is
possible that the amine moiety remains coordinated to
the unreacted AgBF4 (or the in situ produced AgCl) and
hence cannot exert any influence on the course of the
catalysis. This assertion is consistent with the results
of experiments which showed that the catalysis with
2/styrene in the presence of added AgBF4 (run 3, Table
2) gave results intermediate between the catalysis with
2/styrene and that with 1/AgBF4/styrene (runs 2 and
10, Table 2). Added AgCl had no influence in the
catalysis, probably because of its poor solubility (run 4,
Table 2). We believe that these results indicate that the
amine moiety in these complexes plays an important
role in modulating these catalytic reactions. It should
be noted, however, that the observed differences in the
outcomes of the polymerizations catalyzed by 2 and
1/AgBF4 might also be due to the presence of some side
products generated in the latter system.11
3
a
10 1/AgBF4 2000
11 1/AgBF4 2000
12 1/AgBF4
13 1/AgBF4
14 1/AgBF4
15 1/AgBF4
16 1/AgBF4
1531
2066
insolb
insolc
6935
a
a
1000
1000
100
200
300
a
350
a
300
200
100
1.4 400
a
a
7184d 1.5 200
7370e 1.5 300
a
b
[Ag]/[Ni] ) 10. DSC analysis shows exothermic decomposi-
tion starting at 300 °C (before mp). c DSC analysis shows exo-
d
thermic decomposition starting at ca. 290 °C (before mp). Par-
tially soluble in THF. DSC analysis shows exothermic decomposition
starting at 270 °C (before mp). e Slightly soluble in THF. A DSC
analysis shows exothermic decomposition starting at 300 °C (before
mp).
Å).1e Similar structural parameters have been found in
the recently reported Cp analogue [(η5:η1-Cp(CH2)2-
NMe2)Ni(PPh3)]+,7 although there is little distortion in
the hapticity of the Cp ligand in this compound.8
Ca ta lytic Rea ction s. The availability of a pre-
formed, stable cationic Ni compound in which one
coordination site is occupied by a relatively labile amine
moiety (vide infra) presented an opportunity to study
the catalytic reactivities of 2. Mindful of the catalytic
activities of a number of cationic Ni(II) complexes in
olefin oligomerization and polymerization reactions,9 we
proceeded to examine the reactivities of complex 2 with
alkenes. Our objective was to establish whether the
proximity of the amine moiety to the Ni center would
have a major influence on the course of the catalysis.
Complex 2 reacted only very sluggishly with styrene
at room temperature (run 1, Table 2), implying that the
displacement of the amine moiety by styrene is not
facile. However, heating the mixture to 80 °C acceler-
ated the polymerization and gave a soluble polystyrene
(7) Segnitz, O.; Winter, M.; Merz, K.; Fisher, R. Eur. J . Inorg. Chem.
2000, 2077.
(8) For a detailed study on the hapticity in the analogous Ni(Cp)
complexes see: Holland, P. L.; Smith, M. E.; Andersen, R. A.; Bergman,
R. G. J . Am. Chem. Soc. 1997, 119, 12815
Another catalytic reaction which was studied briefly
is the dehydrogenative oligomerization of PhSiH3. Com-
plex 2 was found to catalyze the dimerization of PhSiH3
at room temperature to give PhH2Si-SiPhH2 in ca. 20
turnovers as well as small amounts of the trimer and
tetramers.12 As was the case for the reactions of styrene
and norbornene, here too the outcome of the catalysis
(9) (a) J ohnson, L. K.; Killian, C. M.; Arthur, S. D.; Feldman, J .;
McCord, E. F.; McLain, S. J .; Kreutzer, K. A.; Bennett, M. A.; Coughlin,
E. B.; Ittel, S. D.; Parthasarathy, A.; Tempel, D. J .; Brookhart, M. S.,
DuPont, WO 96/23010, 1996. (b) J ohnson, L. K.; Killian, C. M.;
Brookhart, M. S. J . Am. Chem. Soc. 1995, 117, 6414. (c) Keim, W.;
Appel, R.; Gruppe, S.; Knoch, F. Angew. Chem. 1987, 99, 1042. (d)
Ostoja-Starzewski, K. A.; Witte, J . Angew. Chem. 1985, 97, 610. (e)
Flid, V. R.; Kuznetsov, V. B.; Grigor’ev, A. A.; Belov, A. P. Kinet. Catal.
2000, 41(5), 604. (f) Flid, V. R.; Manulik, O. S.; Grigor’ev, A. A.; Belov,
A. P. Kinet. Catal. 2000, 41(5), 658. (g) Goodall, B. L.; Benedikt, G.
M.; McIntosh, L. H.; Barnes, D. A. U.S. Patent 5,468,819, 1995. (h)
Goodall, B. L.; Benedikt, G. M.; McIntosh, L. H.; Barnes, D. A.; Rhodes,
L. F. U.S. Patent 5,468,819, 1995. (i) Bonnet, M. C.; Dahan, F.; Ecke,
A.; Keim, W.; Schulz, R. P.; Tkatchenko, I. J . Chem. Soc., Chem.
Commun. 1994, 615. (j) Aresta, M.; Dibenedetto, A.; Quaranta, E.;
Lanfanchi, M.; Tiripicchio, A. Organometallics 2000, 19, 4199. (k)
Ihara, E.; Fujimura, T.; Yasuda, H.; Maruo, T.; Kanehisa, N.; Kai, Y.
J . Polym. Sci., Part A: Polym. Chem. 2000, 38, 4764.
(10) Fontaine, F.-G.; Dubois, M.-A.; Zargarian, D. Unpublished
results.
(11) (a) We thank one of the reviewers for pointing out this
possibility. (b) It should be noted that styrene can be polymerized by
Ag+ (Hermans, J . P.; Smets, G. J . Polym. Sci., Part A 1965, 3, 3175),
but this reaction is much slower than that catalyzed by the 1/AgBF4
and requires higher temperatures (above 70 °C).

3814 Organometallics, Vol. 20, No. 17, 2001
Groux and Zargarian
Sch em e 3. Rea ctivity of 2 w ith P h osp h in es
by 2 is qualitatively different from the analogous
reaction catalyzed by the in situ generated cation, which
gives (PhSiH)n consisting of both cyclic (Mn ) ca. 600)
and linear (Mn ) ca. 1500) oligomers.1d At this stage,
we speculate that the dehydrogenative oligomerization
of PhSiH3 catalyzed by 2 does not proceed beyond
dimerization because the dimer produced in the initial
Si-Si bond formation step cannot compete effectively
with the NMe2 moiety for coordination to Ni. In contrast
to the case with the olefin polymerizations, the combi-
nation of (η3:η0-Ind(CH2)2NMe2)(PPh3)Ni-Cl and AgBF4
did not catalyze the oligomerization of PhSiH3.
The above results indicated that the strength of the
coordination of the amine tether to the Ni center can
determine the ease with which the catalytic reactions
may be initiated (e.g., requirement for heating) and can
affect the overall outcome of the reactions (e.g., oligo-
merization vs polymerization). To evaluate the binding
strength of the amine tether, we have studied the
reaction of complex 2 with various neutral and anionic
ligands, as follows.
The reaction of 2 with PMe3 was less straightforward,
and its outcome depended on the relative amount of
PMe3 present in the reaction medium. For instance,
reacting 2 with an excess of PMe3 gave free PPh3 and
Ni(PMe3)414 as the major products, whereas the reaction
with 1 equiv of PMe3 gave, in addition to free PPh3 and
small amounts of Ni(PMe3)4, two new species with the
following spectral features (Table 4): the major species
displayed an AX set of doublets at -10.9 and 41.0 ppm
for PMe3 and PPh3, respectively (2J P-P ) 42 Hz), while
the minor product gave a singlet at -16.6 ppm in 31P-
{1H} NMR spectroscopy. The AX resonances are virtu-
ally identical with the signals displayed by the known1e
bis(phosphine) compound [(1-Me-Ind)Ni(PPh3)(PMe3)]+
Liga n d Su bstitu tion Rea ction s w ith Neu tr a l
Lew is Ba ses. No reaction was observed between 2 and
CO even with a 25 psi pressure of CO, but phosphines
and some amines did react to displace the amine tether
to varying degrees. Thus, only 1 equiv of bis(diphenyl-
phosphino)ethane (dppe) was sufficient to displace both
the amine tether and the PPh3 ligand in 2, giving an
orange-red powder. Recrystallization of this material
from Et2O/CH2Cl2 gave, in ca. 64% yield, the complex
[(η3:η0-Ind(CH2)2NMe2)Ni(dppe)][BPh4] (3), whose iden-
tity was confirmed by elemental analysis and NMR
spectroscopy. The absence of a C2 axis in 3 renders the
two P nuclei of the dppe ligand inequivalent, and so the
31P{1H} NMR spectrum displays two broad signals at
65.6 and 68.7 ppm at room temperature. At -40 °C, the
two signals appear as sharp doublets at 66.4 and 70.8
ppm (2J P-P ) 25.4 Hz), whereas warming to 35 °C brings
about coalescence (broad signal at 66.6 ppm); an energy
barrier of 14.3 kcal mol-1 was calculated for this process
using the Holmes-Gutowski equation.13 Similar dy-
namic exchange processes have been observed for other
complexes of this family and are attributed to the
hindered rotation of the indenyl moiety.1e,h
2
(cf. -10.1 and 41.2 ppm and J P-P ) 42 Hz for one
rotamer),15 and so we propose that the major product
of the reaction of 1 equiv of PMe3 with 2 is [(η3:η0-
Ind(CH2)2NMe2)Ni(PPh3)(PMe3)][BPh4] (5). The minor
product is presumably the complex [(η3:η1-Ind(CH2)2-
NMe2)Ni(PMe3)]+, arising from the displacement of the
PPh3 from 2 by PMe3. These assignments are somewhat
tentative, however, because all attempts at separation
and isolation of these products have resulted in the
formation of intractable materials, thus preventing their
conclusive characterization.
The reaction of 2 with primary and secondary amines
such as H2NEt, HNEt2, aniline, and H2N(t-Bu) gave
complex mixtures of products (by 1H NMR) in which the
only P-containing species was free PPh3 (by 31P{1H}
NMR) and from which no tractable compounds could be
isolated. Tertiary amines such as NEt3 do not react at
all with 2, even in a large excess, but pyridine and its
methyl-substituted analogues showed reactivities simi-
lar to that observed with PPh3 (Scheme 4). As was the
case with PPh3, we were unable to isolate the new
compounds because removal of the excess ligand during
isolation re-formed 2; nevertheless, the identity of the
products can be ascertained from the following NMR
In contrast to the facile reaction with dppe, disruption
of the ΝfNi chelation in 2 by PPh3 is much less
favorable thermodynamically and requires a large ex-
cess of PPh3. The reaction can be monitored by the
emergence in the 31P{1H} NMR spectrum of a new set
of AB resonances at 32.3 and 36.1 ppm (2J P-P ) 27 Hz).
These signals are very similar to those reported1d for
2
[(1-Me-Ind)Ni(PPh3)2]+ (cf. 32.5 and 35.8 ppm, J P-P
)
25 Hz), and so the product of this reaction is proposed
to be [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)2][BPh4] (4). Sepa-
ration and isolation of pure 4 has not been possible
because of the small Keq value of ca. 0.9 for this reaction
(Scheme 3).
1
data. The H NMR spectra of the mixtures of 2 and the
pyridines indicated the formation of a new compound
in equilibrium with 2. The signals arising from the Ind
protons in the new compound were very similar to those
(14) This compound is identified by its singlet resonance (at ca.
-21.5 ppm) in the 31P{1H} NMR spectrum: Tolman, C. A.; Seidel, W.
C.; Gosser, L. W. J . Am. Chem. Soc. 1974, 96, 53.
(12) These products were identified on the basis of their character-
istic 1H NMR signals as reported in: (a) Gauvin, F. Ph.D. Thesis,
McGill University, Montre´al, Que´bec, Canada, 1992. (b) Aitken, C.;
Barry, J .-P.; Gauvin, F.; Harrod, J . F.; Malek, A.; Rousseau, D.
Organometallics 1989, 8, 1732.
(15) It is interesting to note that the 31P{1H} spectrum of [(1-Me-
Ind)Ni(PPh3)(PMe3)]+ shows two sets of signals (AX and A′X′) at-
tributed to the nonequivalent rotamers arising from the hindered
rotation of the indenyl ring,1d whereas compound 5 shows only one
set of signals at room temperature, presumably because of a higher
rotational barrier.
(13) (a) ∆Gq ) RTc[22.96 + ln(Tc/∆δ)]. (b) Abraham, R. J .; Loftus,
P. Proton and Carbon-13 NMR Spectroscopy: an Integrated Approach;
Wiley: Toronto, 1985; pp 165-168.

[(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4]
Organometallics, Vol. 20, No. 17, 2001 3815
Sch em e 4. Equ ilibr iu m Rea ction of 2 w ith
P yr id in e a n d P yr id in e An a logu es
tion by iodine atoms, and the presence of LiBPh4‚H2O
in the crystal lattice prevented us from refining the
structure to a satisfactory level.
Con clu sion . The results of the ligand substitution
reactions described above show that the coordination
of the tether in 2 is strong enough to stabilize this
compound and prevent the formation of the catalytically
inert complex [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)2]+ yet
labile enough to be displaced by relatively strong
ligands. Thus, the amine tether in complex 1 can act as
a hemilabile ligand which can stabilize cationic species
such as 2 while allowing the coordination of some
ligands and substrates. This property facilitates the use
of complex 2 as a single-component precatalyst for the
polymerization of styrene, oligomerization of nor-
bornene, and dimerization of PhSiH3. Comparisons with
the analogous reactions catalyzed by cations generated
in situ from (1-Me-Ind)(PPh3)Ni-Cl and (η3:η0-Ind(CH2)2-
NMe2)(PPh3)Ni-Cl indicate that the presence of the
amine tether has a marked influence on the course of
the catalysis. Future studies will investigate the reac-
tivity of 2 with ethylene and other olefins, and will focus
on understanding the role of the amine tether in the
catalysis.
Ta ble 3. Sp ectr oscop ic Da ta a n d Equ ilibr iu m
Con sta n ts of
[(η3:η0-In d (CH2)2NMe2)Ni(P P h 3)(L)][BP h 4]
1H (ppm)
31P{1H}
L
(ppm)
H2
H3
NMe2
Keq
6a
6b
6c
6d
6e
pyridine
32.13
28.76
32.15
32.06
32.03
6.28 4.18
6.38 4.07
6.35 4.17
6.28 4.15
6.39 4.15
2.14
2.07
2.14
2.04
2.11
9 ( 1
2.0 ( 0.2
23 ( 2
33 ( 3
16 ( 1
2-picoline
3-picoline
4-picoline
3,5-lutidine
of 2, whereas the signals for the protons on the tether
were broadened as a result of the exchange reaction.
Significantly, a new singlet at ca. 2.1 ppm replaced the
previosuly inequivalent N-Me resonances at 1.6 and
1.3 ppm. The 31P{1H} NMR spectra of the mixtures of
2 and the pyridines showed the conversion of 2 to new
derivatives which displayed a singlet resonance at ca.
32 ppm for all but one case; the corresponding signal
for the reaction with 2-picoline appeared at ca. 29 ppm.
These observations are consistent with the formation
of the cations [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)(L)][BPh4]
(6; Table 3), which arise from the displacement of the
tether in 2. The more upfield 31P{1H} signal in the
2-picoline derivative 6b implies a less efficient PPh3fNi
donation due to larger steric interactions between PPh3
and 2-picoline. The equilibrium constants for these
exchange reactions were determined to be 33 (4-pi-
coline), 23 (3-picoline), 16 (3,5-lutidine), 9 (pyridine), and
2.0 (2-picoline). The relative values of Keq reflect the
sensitivity of this ligand substitution reaction to both
steric and electronic factors: pyridine > 2-picoline
(steric factor); 4-picoline > 3-picoline > 3,5-lutidine >
pyridine (electronic factor).
Exp er im en ta l Section
Gen er a l Com m en ts. All manipulations, except for the GPC
and DSC analyses, were performed under an inert atmosphere
of N2 or argon using standard Schlenk techniques and a
drybox. Dry, oxygen-free solvents were employed throughout.
The syntheses of 1 and 2 have been reported previously.4
LiPPh2 and LiNMe2 were prepared by deprotonation of HPPh2
and HNM2, respectively; all other reagents used in the
experiments were obtained from commercial sources and used
as received. The elemental analyses were performed by the
Laboratoire d’analyse e´le´mentaire (Universite´ de Montre´al).
The spectrometers used for recording the NMR spectra are as
follows: Bruker AMXR400 (1H (400 MHz), 13C{1H} (100.56
MHz), and 31P{1H} (161.92 MHz)), and Bruker AV300 (1H (300
MHz) and 31P{1H} (121.49 MHz)).
Cr ysta l Str u ctu r e Deter m in a tion s. Dark red crystals of
2 were obtained at room temperature by the slow diffusion of
Et2O vapor into a CH2Cl2 solution of 2. The crystal data for 2
were collected on a Nonius CAD-4 diffractometer with graphite-
monochromated Cu KR radiation at 293(2) K using CAD-4
software. The refinement of the cell parameters was done with
the CAD-4 software,18 and the data reduction used NRC-2 and
NRC-2A.19 The structure was solved by direct methods using
SHELXS9720 and difmap synthesis using SHELXL96;21 the
refinements were done on F2 by full-matrix least squares. All
non-hydrogen atoms were refined anisotropically, while the
hydrogens (isotropic) were constrained to the parent atom
using a riding model. Crystal data and experimental details
for 2 are listed in Table 1, and selected bond distances and
angles are listed under the ORTEP diagram.
Rea ctivities of 2 w ith An ion ic Liga n d s. The
anionic nucleophiles Ph2P-, Me2N-, and Me- did not
show any reactivity with 2 in Et2O and THF, presum-
ably because of the limited solubility of 2 in these
solvents. Even in CH2Cl2, in which it is soluble, 2 did
not react with Cl- or Br- but reaction with a large
excess of LiI resulted in the formation of a red powder
which was crystallized from CH2Cl2/hexane/Et2O to give
(η3:η0-Ind(CH2)2NMe2)(PPh3)Ni-I‚LiBPh4 (7) in 84%
yield.16 Complex 7 has been characterized completely,
P olym er iza tion of Styr en e. Ru n s 1 a n d 2. 2 (18 mg) and
styrene (4.5 g, 2000 equiv.) were stirred for 7 days in CH2Cl2
(8 mL) at room temperature (run 1) or for 2 days at 80 °C (run
1
including a single-crystal X-ray analysis. The H NMR
(17) Dubois, M.-A. M.Sc. Thesis, Universite´ de Montre´al, Montre´al,
Que´bec, Canada, 1999.
(18) CAD-4 Software, Version 5.0; Enraf-Nonius, Delft, The Neth-
erlands, 1989.
(19) Gabe, E. J .; Le Page, Y.; Charlant, J .-P.; Lee, F. L.; White, P.
S. J . Appl. Crystallogr. 1989, 22, 384.
(20) Sheldrick, G. M. SHELXS: Program for the Solution of Crystal
Structures; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(21) Sheldrick, G. M. SHELXL: Program for the Refinement of
Crystal Structures; University of Go¨ttingen, Go¨ttingen, Germany,
1996.
spectrum of this compound was very similar to that of
1, and the 31P{1H} NMR showed a singlet at 35.9 ppm
(Table 4). The X-ray data we have obtained for complex
7 confirmed the connectivity, but the poor quality of the
crystals, the significant absorption of the Cu KR radia-
(16) The analogous Cp derivative has been reported without char-
acterization data: Nlate, S.; Herdweck, E.; Fischer, R. A. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1861.

3816 Organometallics, Vol. 20, No. 17, 2001
Ta ble 4. 31P {1H} NMR Da ta of Com p lexes 1-7
Groux and Zargarian
compd
no.
δ (ppm)a
2J P-P (Hz)
ref
(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)Cl
[(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4]
[(η3:η0-Ind(CH2)2NMe2)Ni(dppe)][BPh4]
[(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)(PMe3)][BPh4]
[(1-Me-Ind)Ni(PPh3)(PMe3)][BPh4]
[(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)2][BPh4]
[(1-Me-Ind)Ni(PPh3)2][BPh4]
1
2
3
4
30.8b
29.1
4
4
70.8, 66.4c
41.0, -10.9
41.2, -10.1
36.1, 32.3
32.5, 35.8
32.1
25.4c
42
42
27
25
1e
1e
5
[(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)(Py)][BPh4]
(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)I.LiBPh4
(1-Me-Ind)Ni(PPh3)I
6a
7
35.9
38.6b
17
a
b
Unless otherwise stated, all spectra are run in CDCl3 at room temperature. C6D6. c At -40 °C.
2). For run 1, removal of the solvent and unreacted styrene
gave a thin film which was washed with CDCl3 and analyzed
by 1H NMR spectroscopy, showing broad peaks of polystyrene.
For run 2, removal of solvent and unreacted styrene gave a
light gray solid (829 mg, 18% yield), which was isolated and
analyzed by GPC (THF; Mw ) 77 338; Mw/Mn ) 3.15) and NMR
spectroscopy. 1H NMR (CDCl3): δ 7.05 (br), 6.59 (br), 1.85 (br),
1.45 (br). 13C{1H} (CDCl3): δ 145.5 (ipso-C), 128.1 (o- and m-C),
125.5 (p-C), 43.7 and 40.5 (alkyl chain).
Ru n s 3 a n d 4. 2 (15 mg), styrene (3.8 g, 2000 equiv), and
AgCl (26 mg, run 3) or AgBF4 (35 mg, run 4) were stirred for
2 days in CH2Cl2 (8 mL) at 80 °C. Removal of the solvent and
unreacted styrene gave a thick gray oil, which was isolated
and analyzed by GPC (run 3, 1.7 g, 43% yield, GPC (THF)
Mw ) 65 980, Mw/Mn ) 1.2; run 4, 1.9 g, 49% yield, GPC (THF)
Mw ) 12 726; Mw/Mn ) 1.9).
Ru n s 10 a n d 11. Styrene (8.3 g, 2000 equiv) and CH2Cl2
(8 mL) were syringed into a mixture of 1 (22 mg) and AgBF4
(85 mg, 10 equiv). The solution was stirred for 2 days at room
temperature (run 10) or at 60 °C (run 11). Removal of the
solvent and the unreacted styrene under vacuum gave poly-
styrene (run 10, thick oil, 6.9 g, 83% yield; run 11, sticky solid,
9.0 g, 79% yield), which was analyzed by GPC (THF; run 10,
Mw ) 1531, Mw/Mn ) 1.29; run 11, Mw ) 2066, Mw/Mn ) 1.48).
P olym er iza tion of Nor bor n en e. Ru n s 5 a n d 6. 2 (ca.
19 mg) and norbornene (ca. 2.3 g, 1000 equiv) were stirred in
CH2Cl2 (3 mL) for 4 days at room temperature (run 5) or at
80 °C (run 6). Removal of the solvent and unreacted nor-
bornene left only unreacted 2 (run 5) or a gray solid (run 6,
The results are presented in Table 2. Integration of alkane vs
aromatic protons in 1H NMR spectroscopy showed that co-
polymers were formed that kept the starting proportion of
styrene and norbornene. The results of the GPC analyses (in
THF) were as follows: run 14, totally soluble, Mw ) 6935, Mw/
Mn ) 1.4; run 15, partially soluble, Mw ) 7184, Mw/Mn ) 1.5;
run 16, slightly soluble, Mw ) 7370, Mw/Mn ) 1.5. Thermal
analysis of the solids obtained from runs 15 and 16 showed
exothermic degradations of the polymers (at ca. 300 °C), giving
a black powder after the analysis.
Deh yd r op olym er iza tion of P h en ylsila n e. Into a vessel
containing 1 (ca. 15 mg) and AgBF4 (ca. 55 mg, 10 equiv) was
syringed a CH2Cl2 solution (3 mL) containing PhSiH3 (ca. 600
mg, 200 equiv) and the mixture stirred for 3 days at room
temperature or at 80 °C. Removal of the solvent and the
remaining PhSiH3 gave a black oil, which was analyzed by 1H
NMR spectroscopy. None of the signals characteristic12 of
(PhSiH2)2 or the (PhSiH)n oligomers were detected. 2 (25.8 mg,
0,031 mmol) and PhSiH3 (676 mg, 6.25 mmol) were stirred
for 3 days in CH2Cl2 (2 mL) at room temperature. Removal of
the volatiles gave a colorless oil, which was analyzed by 1H
NMR spectroscopy. Signals characteristic12 of the dimer (the
major product, 4.49 ppm) and the trimer and tetramer (broad
signals at 4.56 ppm) were detected, while the signals for linear
or cyclic polymers were absent.
[In d (CH2)2NMe2)Ni(d p p e)][BP h 4] (3). Overnight stirring
of a CH2Cl2 (15 mL) mixture of 2 (415 mg, 0.503 mmol) and
dppe (201 mg, 0.505 mmol), followed by removal of the solvent,
gave a red-orange solid. Two recrystallizations from CH2Cl2
and Et2O (1:10) gave an orange powder (309 mg, 0.32 mmol,
64% yield). 31P{1H} NMR (CDCl3): δ 68.66 (br) and 65.65 (br).
1H NMR (CDCl3): δ 7.15 and 6.96 (t, H5 and H6), 7.6 to 6.7
(m, -PPh2, BPh4), 6.53 (br d, J 8.1 Hz, H4 or H7), 6.02 (br,
H2), 5.92 (d, J ) 8.2 Hz, H4 or H7), 5.31 (d, J ) 2.8 Hz, H3),
2.24 (m, Ind-CH2-), 2.03 (s, NMe2), 1.90 (m, -CH2-N), 1.69
(m, -CH2P). 13C{1H} NMR (CDCl3): δ 163.5 (4-line multiplet,
J B-C ) 48 Hz, i-C of BPh4), 136.4 (m-C of BPh4), 133.3 (d,
2J P-C ) 8 Hz, o-C of PPh2), 132.2 (p-C of PPh2), 129.6 (d,
3J P-C ) 11 Hz, m-C of PPh2), 128.0 and 127.8 (C5/C6), 125.64
(o-C of BPh4), 121.7 (p-C of BPh4), 119.7 (d, J P-C ) 9 Hz, C1),
118.3 and 118.0 (C4/C7), 101.5 (C2), 79.8 (C3), 58.8 (CH2N),
45.2 (NMe), 30.6 and 27.6 (br m, PCH2), 24.6 (Ind-CH2), Anal.
Calcd for C63H60P2NiBN‚CH2Cl2: C, 73.38; H, 5.96; N, 1.34.
Found: C, 73.05; H, 6.03; N, 1.23.
101 mg, 4.4% yield), which was analyzed by GPC (THF; Mw
763; Mw/Mn ) 1.1).
)
Ru n s 12 a n d 13. CH2Cl2 (8 mL) is added to 1 (ca. 23 mg),
AgBF4 (ca. 80 mg, 10 equiv), and norbornene (ca. 4.0 g, 1000
equiv). A white solid precipitated immediately after the
addition of the solvent. After 2 days at room temperature (run
12) or at 60 °C (run 13), a gray insoluble solid (run 12, 1.1 g,
27% yield; run 13, 1.2 g, 35% yield) was obtained. Thermal
analysis (DSC) of the polymers showed an exothermic decom-
position starting at 300 °C, giving a black powder after the
analysis.
Cop olym er iza tion of Styr en e a n d Nor bor n en e. Ru n s
7-9. 2 (ca. 20 mg) was reacted with styrene and norbornene
(with ratios of 300:100 (run 7), 200:200 (run 8), and 100:300
(run 9)) for 2 days in CH2Cl2 (2 mL) at 50 °C. The solvent and
the unreacted monomers were then removed under vacuum
to give a thick oil, which was isolated (yields ca. 5% (run 7),
2% (run 8), and 1% (run 9)) and analyzed by 1H NMR
spectroscopy and GPC (THF). Integration of the alkane vs
aromatic protons in the 1H NMR spectra showed that the
product obtained was polystyrene.
Rea ction of 2 w ith P P h 3. The 1H and 31P{1H} NMR
spectra of a CDCl3 solution of 2 (18.5 mg, 0.022 mmol) and
PPh3 (95 mg, 0.36 mmol) showed the emergence of a new
1
species. H NMR: δ 7.0-7.9 (br m, aromatic signals of PPh3,
3
BPh4, and Ind), 6.81 (H2), 6.37 (d, J H-H ) 7.6 Hz, H4 or H7),
3
6.08 (d, J H-H ) 7.0 Hz, H4 or H7), 4.94 (H3), 2.11 (NMe2);
Ru n s 14-16. Stirring 1 (ca. 18 mg) and AgBF4 (ca. 65 mg)
with mixtures of styrene and norbornene (with ratios of 300:
100 (run 14), 200:200 (run 15), and 100:300 (Run 16)) for 3
days in CH2Cl2 (3 mL) at 50 °C gave, after removal of solvent
and unreacted monomers, a gray solid, which was isolated
(yields: run 14, >95%; run 15, 75%; run 16, 56%) and analyzed
by 1H NMR spectroscopy, GPC, and DSC (runs 15 and 16).
broad signals for Ind-CH2 and CH2N protons of the new
species and of 2 are overlapping. 31P{1H} NMR δ 35.9 and 32.1
2
(d, J P-P ) 27 Hz, PPh3). The new signals are attributed to
the complex [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)2][BPh4] (4). A 1:3
mixture of 4 and 2 was ascertained from the integration of
the respective signals. Additional PPh3 (0.37 mmol, 97 mg) was
then added to the solution, and the NMR spectra were recorded

[(η3:η1-Ind(CH2)2NMe2)Ni(PPh3)][BPh4]
Organometallics, Vol. 20, No. 17, 2001 3817
15 min later, showing a 1:1 ratio. Removal of the solvent and
washing with Et2O gave a reddish solid, the 31P NMR spectrum
of which shows only a small signal for 2 and traces of unknown
compounds.
rium constants were derived as explained for 6a and are
tabulated in Table 3, together with the spectroscopic data.
[(η3:η0-In d (CH 2)2NMe2)Ni(P P h 3)I]‚LiBP H 4 (7). Com-
pound 2 (508 mg, 0.615 mmol) and LiI (1.6 g, 12.3 mmol) were
stirred for 2 h in CH2Cl2 (15 mL), and the mixture was then
filtered. Evaporation of the filtrate gave a red powder of crude
7, which was dissolved in 4 mL of CH2Cl2 and precipitated by
addition of a 1:1 solution of hexane and Et2O to give the pure
product as a red powder (497 mg, 0.518 mmol, 84% yield).
Rea ction of 2 w ith P Me3. PMe3 (28.5 µL, 0.28 mmol) was
transferred to a stirred solution of 1 (230 mg, 0.28 mmol) in 7
mL of CH2Cl2. Analysis of the resulting red solution by 31P{1H}
NMR spectroscopy showed the presence of a few species
(CDCl3): δ 41.1 (d, 2J P-P ) 42, PPh3), -10.8 (d, 2J P-P ) 42 Hz,
PMe3), 29.5 (s, unreacted 2), 16.5 (s), -4.5 (s, free PPh3), -21.5
(s, Ni(PMe3)4). The signals at δ 41.1 and -10.8 are attributed
to [(η3:η0-Ind(CH2)2NMe2)Ni(PPh3)(PMe3)][BPh4] (5). Removal
of the solvent gave a red powder consisting mainly of 2 (187
mg, 20.1 mmol, 71% crude yield).
1
31P{1H} NMR (CDCl3): δ 35.94. H NMR (CDCl3): δ 7.6-6.7
3
(m, BPh4. PPh3, aromatic proton of Ind), 6.24 (d, J H-H ) 5.2
Hz, H4), 6.11 (s, H2), 4.05 (m, H3), 2.50 (m, Ind-CH2-), 2.17
(m, -CH2-N), 2.03 (s, NMe2). 13C{1H} NMR (C6D6): δ 164.2
(4-line multiplet, J B-C ) 42 Hz, i-C of BPh4), 136.1 (m-C of
[(η3:η0-In d(CH2)2NMe2)Ni(P P h 3)(P y)][BP h 4] (6a) in Equ i-
libr iu m w ith 2. Compound 2 (19.3 mg, 0.023 mmol) and
pyridine (13.8 µL, 0.17 mmol) were mixed together in CDCl3
and the 1H and 31P{1H} NMR spectra recorded 15 min later,
showing a 2:1 ratio of 6a and 2 on the basis of the integration
BPh4), 135.4 (d, J P-C ) 9 Hz, o-C of PPh3), 132.9 and 132.1
2
(C3A/C7A), 130.7 (p-C of PPh3), 128.4 (d, 3J P-C ) 9 Hz, m-C of
PPh3), 128.8 and 127.4 (C5/C6), 126.3 (o-C of BPh4), 122.4 (p-C
2
of BPh4), 118.4 & 117.5 (C4/C7), 101.1 (d, J P-C ) 25 Hz, C1),
95.2 (C2), 75.1 (C3), 55.8 (CH2N), 43.51 (NMe), 23.2 (IndCH2).
Anal. Calcd for C55H51LiBNPNiI: C, 68.79; H, 5.35; N, 1.46.
Found: C, 68.23; H, 4.90; N, 1.58.
1
of the 31P{1H} NMR signals. H NMR (CDCl3): δ 8.6-6.8 (m,
aromatic protons of PPh3, Ind, and pyridine), 6.60 and 6.52
(H4/H7), 6.28 (br, H2), 4.18 (s, H3), 2.14 (s, NMe2); the signals
for Ind-CH2 and CH2N of 6a and 2 are overlapping. 31P{1H}
NMR (CDCl3): δ 32.2 (s).
Ack n ow led gm en t. Francine Be´langer-Garie´py and
Ernesto Rivera-Garcia are gratefully acknowledged for
their help with the crystallography and the GPC stud-
ies, respectively. The Natural Sciences and Engineering
Research Council of Canada, le fond FCAR of Quebec,
and the University of Montreal are gratefully acknowl-
edged for financial support.
More pyridine (13.8 µL, 0.17 mmol) was then added to the
above sample, and the NMR spectra were recorded 15 min
later, showing a 5:1 ratio of 6a and 2. Removal of volatiles
under vacuum gave a red solid, which was identified as 2 by
1
31P{1H} and H NMR spectroscopy. The equilibrium constants
have been calculated using data obtained from these two sets
of measurements at different concentrations; the integrals of
Su p p or tin g In for m a tion Ava ila ble: Complete details on
the X-ray analysis of 2, including tables of crystal data,
collection and refinement parameters, bond distances and
angles, anisotropic thermal parameters, and hydrogen atom
coordinates, VT NMR spectra of 3, and detailed calculations
of the equilibrium constant for the reaction of 2 with pyridine,
2-picoline, 3-picoline, 4-picoline, 3,5-lutidine, and PPh3. This
material is available free of charge via the Internet at
http://pubs.acs.org.
1
the signals for 2 and 6a in the H (signal for H3) and 31P{1H}
NMR spectra were used for the calculations and gave the same
results within experimental error (see the Supporting Infor-
mation).
[(η3:η0-In d (CH 2)2NMe2)Ni(P P h 3)(L)][BP h 4] (6b-e) in
Equ ilibr iu m w ith 2. Gen er a l P r oced u r e. To a CDCl3 (ca.
0.75 mL) solution of 2 (ca. 20 mg) was added ca. 5-10 µL of L
(2-picoline, 3-picoline, 4-picoline, 3,5-lutidine), and the NMR
spectra were recorded 20 min later. This operation was
repeated once or twice with additional aliquots of L. Equilib-
OM010200Z