Synthesis and reactivity studies on alkyl-aryloxo complexes of nickel containing chelating diphosphines: Cyclometallation and carbonylation reactions

Article abstract of DOI:10.1016/S0022-328X(01)01323-7

Nickel alkyl-aryloxo complexes of composition Ni(R)(O-C₆H₃-2,6-Me₂)(P-P) (R = CH₂SiMe₃, CH₃, CH₂CMe₂Ph; CH₂CMe₂Ph) complexes undergo a cyclometallation reaction that leads to the metallacycles Ni(CH₂CMe₂-o-C₆H₄)(P-P) together with 2,6-dimethylphenol. The alkyl-aryloxo complexes cleanly react with carbon monoxide giving products resulting from CO insertion and reductive elimination, i.e. Ni(CO)₂(P-P) and the corresponding 2,6-dimethylphenyl carboxylates quantitatively.

Full text of DOI:10.1016/S0022-328X(01)01323-7

Journal of Organometallic Chemistry 643–644 (2002) 331–341
www.elsevier.com/locate/jorganchem
Synthesis and reactivity studies on alkyl–aryloxo complexes of
nickel containing chelating diphosphines: cyclometallation and
carbonylation reactions
J. Ca´mpora a, J.A. Lo´pez a, C. Maya a, P. Palma a,*, E. Carmona a,*, P. Valerga b
a Departamento de Qu´ımica Inorga´nica-Instituto de In6estigaciones Qu´ımicas,
Uni6ersidad de Se6illa-Consejo Superior de In6estigaciones Cient´ıficas, c/Americo Vespucio s/n, Isla de la Cartuja, 41092 Se6illa, Spain
b Departamento de Ciencia de Materiales, Ingenieria Metalu´rgica y Qu´ımica Inorga´nica, Facultad de Ciencias, Uni6ersidad de Ca´diz, Apdo 40,
11510 Puerto Real, Ca´diz, Spain
Received 16 July 2001; accepted 27 September 2001
Dedicated to Professor F. Mathey on the occasion of his 60th birthday
Abstract
Nickel alkyl–aryloxo complexes of composition Ni(R)(OꢀC6H3ꢀ2,6-Me2)(PꢀP) (R=CH2SiMe3, CH3, CH2CMe2Ph;
PꢀPꢁPPri2(CH2)nPPri2, n=2 (dippe) or 3 (dippp)) have been synthesized. While the (trimethylsilyl)methyl and the methyl
derivatives are stable in solution at room temperature, the bis-neophyl (R=CH2CMe2Ph) complexes undergo a cyclometallation
¸¹¹¹¹¹¹¹¹º
reaction that leads to the metallacycles Ni(CH2CMe2-o-C6H4)(PꢀP) together with 2,6-dimethylphenol. The alkyl–aryloxo
complexes cleanly react with carbon monoxide giving products resulting from CO insertion and reductive elimination, i.e.
Ni(CO)2(PꢀP) and the corresponding 2,6-dimethylphenyl carboxylates quantitatively. © 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Alkyl; Aryloxide; Carbonylation; Nickel; Metallacycle
pound is involved in CꢀO bond forming and cleavage
reactions [5]. In the present contribution, we describe
1. Introduction
the synthesis of some new nickel derivatives of the
Late transition metal complexes containing alkoxide
bulky ligand 2,6-dimethylphenoxide, stabilized by the
ligands often display interesting reactivity patterns that
chelating diphosphines 1,2-bis(diisopropylphosphino)-
are relevant to the mechanism of several important
ethane (dippe) or 1,3-bis(diisopropylphosphino)propane
catalytic processes [1]. However, the synthesis of these
(dippp), and our first results in the study of their
compounds is often hampered by their low stability and
chemical reactivity.
their tendency to form alkoxo-bridged dimers or even
to polymerize into highly insoluble solids [2]. In con-
trast, aryloxide ligands usually provide higher thermal
stability and tend to coordinate in a terminal form.
2. Results and discussion
Perhaps for this reason, many aryloxides of the Group
The reaction of alkyl complexes with alcohols consti-
10 metals have been prepared and their reactivity stud-
tutes a mild and efficient method for the synthesis of
ied in some detail, among these, several (aryloxo)alkyl
metal alkoxides [2,5,6]. Following this approach, we
complexes of Ni that contain monodentate phosphine
have attempted the preparation of the desired (ary-
[3] or chelating nitrogen ligands [4]. This type of com-
loxo)alkyl complexes by means of the reaction of nickel
dialkyl complexes of composition NiR2(dippe) and
NiR2(dippp) with 2,6-dimethylphenol. The required al-
kyl derivatives 2–3, are actually synthesized by ligand
exchange reactions, using the corresponding pyridine
* Corresponding authors.
E-mail address: ppalma@cica.es (P. Palma).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01323-7

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J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
(py) [7] or N,N,N%,N%-tetramethylethylenediamine
(tmed) [8] complexes as starting materials. The low
thermal stability of these precursors and their high
reactivity toward O2 and H2O pose some experimental
difficulties to this procedure. However, considerable
simplification is introduced by the use of the pyridine
dialkyls 1a,b without previous isolation, so that com-
pounds 2 and 3 may be readily obtained in 50–65%
overall yield (Scheme 1). Attempts to prepare the corre-
sponding 2-methyl-2-phenylpropyl (neophyl) deriva-
tives proved unsuccessful and gave no isolable product.
However, the failure of this procedure has been noted
previously [7], and may be due to the poor thermal
stability of the Ni(CH2CMe2Ph)2(py)2 complex
intermediate.
NMR studies on compounds 2 and 3 are in accord
with the proposed structures. As expected, their
31P{1H} spectra consist of a single peak, while in the
13C{1H} spectra, a more complex resonance is observed
for the Ni-bound C atoms. This appears as an apparent
doublet of doublets in the spectra of the dippe deriva-
tives 2a,b, and as a multiplet in those of the dippp
complexes 3a,b, due to the coupling to the two magnet-
ically inequivalent 31P nuclei. The simulation of the spin
system in the dippe and dippp derivatives shows that,
whereas, for the former it approaches a first order
coupling situation (JPP%:5 Hz), in the case of the latter
the coupling of the 31P nuclei has a significantly larger
value of ca. 25 Hz (Table 1).
pated, complexes 6a–c undergo ligand exchange reac-
tions with dippe or dippp providing 7a–c and 8a–c in
nearly quantitative yield. All these compounds can be
isolated as red or brown crystalline solids, soluble in
hydrocarbon solvents. The X-ray structure of the
trimethylsilyl derivatives 7a and 8a have been deter-
mined, and will be discussed at a later stage (Figs. 1
and 2).
The 31P{1H}-NMR spectra of complexes 7a–b and
8a–b display AX spin systems with small (0–5 Hz) JPP
values for the dippe derivatives and close to 30 Hz for
those of dippp, as previously noted for the dialkyl
complexes. It is likely that these differences are a reflec-
tion of a deviation of the PꢀNiꢀP angle in compounds
8 from the ideal value of 90° (vide infra). In spite of the
relatively large bulk of the ligands attached to the Ni
1
center, the H and 13C spectra of 7–8 display two sets
of signals for the isopropyl groups, and a single methyl
resonance for the 2,6-dimethylphenolate, indicating
that the aryloxide unit rotates freely about the NiꢀO
and CꢀO bonds (Tables 2 and 3).
In contrast with the trimethylsilyl and methyl com-
plexes 7a,b and 8a,b, the neophyl complexes 7c and 8c
are not stable in solution at room temperature. Instead,
they undergo a cyclometallation reaction that cleanly
leads to the metallacycles 9 and 10, together with
2,6-dimethylphenol (Scheme 3). As shown, these com-
plexes can be prepared by an alternative route consist-
ing of a ligand exchange reaction from the previously
known PMe3 derivative 11 [11] (Table 4).
We have shown recently that palladium neophyl
complexes bearing PMe3 ligands can be readily cy-
clometallated under a variety of experimental condi-
tions [12,13]. These studies have provided mechanistic
evidence that suggests the intermediacy of a cationic
p-arene intermediate. It is therefore reasonable to as-
sume that the cyclometallation of the Ni compounds 7c
and 8c follows a similar reaction pathway (Scheme 4),
consisting in the dissociation of the 2,6-dimethylpheno-
late ligand, which subsequently acts as a base, deproto-
nating the cationic intermediate 12. In this regard, it
should be mentioned however, that complex 6c, that is,
the PMe3 analogue of 7c and 8c, is more stable in
solution and does not undergo the cyclometallation
reaction under similar conditions.
Somewhat disappointingly, the dialkyl derivatives 2
and 3 are remarkably inert toward reaction with 2,6-
dimethylphenol, even after prolonged heating at 60 °C
in THF. Therefore, in order to prepare the desired
(aryloxo)alkyl compounds, we have considered as pre-
cursors related complexes of the monodentate phos-
phine PMe3, 4 and 5 (Scheme 2). Use of the known
compounds
Ni(CH2SiMe3)2(PMe3)2
[7a]
and
Ni(R)Cl(PMe3)2 (R=Me, 5b [9]; CH2CMe2Ph, 5c [10])
leads initially to aryloxide complexes 6 and then to the
diphosphine species 7 and 8 (Scheme 2). At variance
with 2a and 3a, the bis(trimethylsilyl) complex 4 reacts
cleanly with 2,6-dimethylphenol at room temperature,
giving rise to 6a. In turn, the analogous methyl (6b) and
neophyl (6c) derivatives are obtained when 5b or 5c are
treated with sodium 2,6-dimethylphenolate. As antici-
The carbonylation of aryloxo(methyl) nickel com-
plexes has been studied by Yamamoto [5], who showed
that it involves the migratory insertion of CO into the
NiꢀC bond followed by reductive elimination of the
corresponding aryl acetate. The aryloxo complexes 7a–
c and 8a–c also react cleanly with CO (20°, 1 atm)
affording the carbonyl complexes Ni(CO)2(PꢀP)
(PꢀPꢁdippe or dippp) together with the expected 2,2-
dimethylphenyl carboxylates in nearly quantitative
yield (Scheme 5). Interestingly, the carbonylation of the
CH2SiMe3 derivatives 7a and 8a also yields the aryl
Scheme 1.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
333
Table 1
31P{1H}-, 1H- and 13C{1H}-NMR data for complexes 2a, 2b, 3a and 3b
a
31P{1H}
1H
3C{1H} a
NiꢀR
NiꢀR
Pri2P(CH)nPPri2
Pri2P(CH)nPPri2
Ni(CH2SiMe3)2- 71.8
(dippe) (2a)
0.30 (m, 4H,
0.87 (dd, 12H, 3JHH=7.2,
−2.4 (m,
18.1 (4C, CH3), 19.7 (4C, CH3)
*JHP=5.7, 14.0, CH2) 3JHP=11.7, CH3)
*JCP=19, 66, CH2) 20.1 (pt, 2C, *JCP=19, CH2)
0.50 (s, 9H, SiCH3)
0.93 (m, 4H, CH2)
5.4 (CH3)
24.2 (d, 4C, 1JCP=18, CH)
1.12 (dd, 12H, 3JHH=7.0,
3JHP=14.2, CH3)
1.99 (h, 4H, 3JHH=7.2, CH)
*
NiMe2(dippe)
(2b)
76.4
0.54 (m, 6H,
*JHP=4.1, 9.3,CH3)
0.85 (dd, 12H, 3JHH=7.0,
3JHP=11.7, CH3)
1.6 (m, JCP
=
18.2 (4C, CH3), 19.4 (4C, CH3)
20, 74, CH3)
21.1 (dd, 2C, 1JCP=21, 2JCP=17,
CH2)
1.01 (m, 4H, CH2)
1.11 (dd, 12H, 3JHH=7.2,
3JHP=14.6, CH3)
24.4 (d, 4C, 1JCP=19, CH)
1.95 (h, 4H, 3JHH=7.8, CH)
Ni(CH2SiMe3)2- 17.3
(dippp) (3a)
0.06 (m, 4H,
*JHP=9.7, CH2)
0.51 (s, 9H, SiCH3)
0.77 (m, 4H, CH2)
0.95 (dd, 12H, 3JHH=7.1,
3JHP=10.5, CH3)
1.20 (dd, 12H, 3JHH=7.4,
3JHP=13.7, CH3)
−0.2 (m, CH2)
5.2 (CH3)
17.7 (4C, CH3)
17.9 (pt, 2C, *JCP=9, CH2), 20.7
(4C, CH3)
21.8 (1C, CH2), 25.0 (4C, CH)
1.42 (m, 2H, CH2)
2.01 (m, 4H, CH)
*
NiMe2(dippp)
(3b)
24.2
0.31 (m, 6H,
*JHP=6.1, CH3)
0.94 (m, 16H, CH3, CH2)
1.23 (dd, 12H, 3JHH=6.8,
3JHP=13.2, CH3)
3.8 (m, JCP
=
18.0 (4C, CH3)
18.2 (pt, 2C, *JCP=12, CH2), 20.7
(4C, CH3)
30, 74, CH3)
1.52 (m, 2H, CH2)
1.95 (h, 4H, 3JHH=6.5, CH)
21.9 (1C, CH2)
25.5 (t, 4C, 1JCP=11, CH)
C6D6, l en ppm, J en Hz.
a Singlets unless otherwise indicated.
acetate 13b, instead of the expected a-trimethysilylac-
etate, due to the hydrolytic cleavage of the SiMe3
group. Since a-trimethylsilyl esters are fairly resistant to
hydrolysis [14], it seems likely that the intermediate
trimethylsilylacetyl complexes are unstable and react
with trace amounts of water to give the observed
products. Hydrolytic cleavage of CꢀSi bonds in transi-
tion metal a-trimethylsilylacetyl or -trimethylsilylimi-
noacetyl complexes to give the corresponding
desilylated products has been observed previously [15].
the PꢀNiꢀP angle in 8a (97.36(13)°) is wider (ca. 9°)
than in 7a (88.52(1)°). This has a noticeable influence
on the disposition of the alkyl and aryloxide ligands,
which are closer in 8a (CꢀNiꢀO=87.8(3)°) than in 7a
(CꢀNiꢀO=91.0(4)°). Apart from this, both molecules
have similar structural parameters. In both complexes,
,
the NiꢀP bonds placed in trans to carbon are ca. 0.1 A
longer than those in trans to oxygen, suggesting a larger
trans influence of the alkyl group as compared with the
aryloxide ligand. Both the alkyl and the aryloxide
groups adopt an alternated conformation that mini-
mizes the steric repulsions with the bulky phosphine
ligands, while the isopropyl substituents are found in a
nearly identical disposition. Several metric features of
the aryloxide ligands evidence some degree of steric
3. Crystal structure of compounds 7a and 8a
,
crowding. Thus, the NiꢀO bond length is 1.907(8) A in
The crystal structures of the aryloxides 7a and 8a are
shown on Figs. 1 and 2. Selected bond lengths and
angles are listed in Tables 5 and 6. In both molecules,
the Ni atoms occupy approximately square planar envi-
ronments, with virtually no tetrahedral distortion, the
sum of the cis LꢀNiꢀL% angles around the nickel center
amount 359.7° in 7a and 360.1° in 8a. As expected for
the different bite angles of the dippe and dippp ligands,
,
7a and 1.915(7) A in 8a. These values are significantly
longer than in other aryloxides of Ni [16], where they
usually cluster within the narrow range of 1.85–1.87 A
[17]. The MꢀOꢀC angles in 7a and 8a are 135.0(7) and
133.1(6)°, respectively, which are somewhat wider than
those encountered in other Group 10 aryloxides, usu-
ally close to 120° [3a,6b–6d,16].
,

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J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
We believe that the relatively large values of the
MꢀO distances and MꢀOꢀC angles in compounds 7a
and 8a are due to the steric repulsions between the
bulky aryloxide and dippe or dippp ligands.
As already pointed out, the NMR spectra of the
aryloxides 7–8 are consistent with unrestricted rotation
of the aryloxide ligand around the CꢀO bond. Hence,
the above solid-state effects noted in the structures of
7a and 8a appear to have no significant influence in
solution. Nevertheless, steric encumbrance could be
important in promoting the dissociation of the arylox-
ide ligand that allows cyclometalation of the neophyl
complexes 7c and 8c to 9 and 10.
4. Concluding remarks
Although the Ni dialkyl complexes 2a,b and 3a,b do
not react with the bulky 2,6-dimethyl phenol, alkyl–
aryloxide complexes 7–8, bearing the chelating diphos-
phines dippe or dippp may be readily prepared from
the corresponding PMe3 derivatives by metathetical
exchange of the phosphine ligands. In general the alkyl
aryloxides exhibit good thermal stability, although
when R=CH2CMe2Ph (neophyl group) they undergo
facile cyclometallation, releasing the free phenol. At
variance with the related Pd and Pt alkyl aryloxides,
this is a relatively uncommon process in Ni chemistry,
and its mechanism might involve the heterolytic dissoci-
ation of the aryloxide ligand. The carbonylation of
complexes 7–8 takes place cleanly, giving rise to the
corresponding aryl esters quantitatively.
Scheme 2.
5. Experimental
Fig. 1. X-ray structure of compound 7a.
Microanalyses were performed by the Analytical Ser-
vice of the University of Seville and the Instituto de
Investigaciones Qu´ımicas. The spectroscopic instru-
ments used were Perkin–Elmer Models 684 and 883
and Bruker Model Vector 22 for IR spectra, and
Bruker AMX-300, DRX-400, AMX-500 and DRX-500
for NMR spectroscopy. The 13C resonance of the sol-
vent was used as an internal standard, but chemical
shifts are reported with respect to SiMe4. The 13C{1H}-
NMR assignments were helped in most cases with the
use of gate-decoupling techniques. 31P{1H}-NMR shifts
are referenced to external 85% H3PO4. All preparations
and other operations were carried out under oxygen-
free nitrogen by conventional Schlenk techniques. Sol-
vents were dried and degassed before use. The
petroleum ether used had a b.p. of 40–60 °C. The
¸¹¹¹¹¹¹¹¹º
compound Ni(CH2CMe2-o-C6H4)ꢀ(PMe3)2 [11] and
phosphines PMe3 [18] and Pri2PCH2CH2PPr2i (dippp)
[19] were prepared according to literature methods.
Fig. 2. X-ray structure of compound 8a.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
335
Table 2
31P{1H}- and 1H-NMR data for complexes 6a–c, 7a–c and 8a–c
a
31P{1H}
1H
NiꢀR
PMe3/Pri2P(CH)nPPri2
OAr b
Ni(CH2SiMe3)(OAr)(PMe3)2 (6a) −20.9
−1.31 (t, 2H, 3JHP=13.8, CH2) 0.81 (sa, 18H, PMe3)
0.28 (s, 9H, SiCH3)
2.98 (s, 6H, Me)
6.65 (t, 1H, 3JHH=6.9, CHar)
7.17 (d, 2H, 3JHH=7.0, CHar)
Ni(Me)(OAr)(PMe3)2 (6b)
−18.0
−22.2
−1.07 (sa, 3H, CH3)
0.74 (s, 18H, PMe3)
0.77 (sa, 18H, PMe3)
3.0 (sa, 6H, Me)
6.66 (t, 1H, 3JHH=7.2, CHar)
7.23 (d, 2H, 3JHH=7.2, CHar)
Ni(CH2CMe2Ph)(OAr)-
(PMe3)2 (6c)
0.41 (t, 2H, 3JHP=13.0, CH2)
1.64 (s, 6H, CMe2)
2.94 (sa, 6H, Me)
6.65 (t, 1H, 3JHH=6.8, CHar)
7.19 (d, 2H, 3JHH=6.2, CHar)
7.06 (t, 1H, 3JHP=7.3, CHar)
7.26 (m, 2H, CHar)
7.61 (d, 2H, 3JHP=7.3, CHar)
Ni(CH2SiMe3)(OAr)(dippe) (7a) 59.4
0.06 (t, 2H, *JHP=7.6, CH2)
0.42 (sa, 9H, SiCH3)
.
0.70 (m, 2H, CH2)
0.80 (m, 12H, CH3)
0.90 (m, 2H, CH2)
1.15 (m, 12H, CH3)
1.75 (m, 4H, CH)
2.94 (s, 6H, Me)
70.6
6.70 (t, 1H, 3JHH=6.9, CHar)
7.25 (d, 2H, 3JHH=7.0, CHar)
Ni(Me)(OAr)(dippe) (7b)
63.0d
75.8d
−0.39 (t, 3H, *JHP=4.7, CH3) 0.77 (m, 2H, CH2)
2.66 (s, 6H, Me)
0.80 (dd, 6H, 3JHP=13.0, 6.86 (t, 1H, 3JHH=7.3, CHar)
3JHH=7.0, CH3)
2JPP=10
0.98 (m, 2H, CH2)
1.05 (m, 12H, CH3)
1.37 (dd, 6H, 3JHP=14.7,
3JHH=7.2, CH3)
7.34 (d, 2H, 3JHH=7.3, CHar)
1.58 (m, 2H, CH)
1.98 (m, 2H, CH)
Ni(CH2CMe2Ph)(OAr)(dippe)
(7c)
57.7
65.7
1.49 (dd, 2H, 3JHP=4.8, 12.6,
CH2)
1.66 (s, 6H, CMe2)
0.60 (m, 2H, CH2)
2.95 (s, 6H, Me)
0.73 (dd, 6H, 3JHP=12.6, 6.53 (t, 1H, 3JHH=7.0, CHar)
3JHH=6.8, CH3)
7.02 (t, 1H, 3JHP=7.2, CHar)
7.16 (t, 2H, 3JHP=7.2, CHar)
0.89 (m, 8H, CH3, CH2)
1.03 (dd, 6H, 3JHP=15.3,
3JHH=7.2, CH3)
7.31 (d, 2H, 3JHH=7.2, CHar)
7.33 (d, 2H, 3JHP=7.3, CHar)
1.29 (dd, 6H, 2JHP=14.9,
3JHH=7.2 CH3)
1.90 (m, 4H, CH)
Ni(CH2SiMe3)(OAr)(dippp) (8a) 5.1d
−0.08 (dd, 2H, 3JHP=6.2, 8.8,
CH2)
0.30 (sa, 9H, SiCH3)
0.60 (m, 4H, CH2)
2.98 (s, 6H, Me)
29.4d
0.90 (m, 12H, CH3)
6.76 (t, 1H, 3JHH=7.2, CHar)
2JPP=37
1.32 (m, 14H, CH3, CH2) 7.27 (d, 2H, 3JHH=7.3, CHar)
1.80 (m, 2H, CH)
2.17 (m, 2H, CH)
Ni(Me)(OAr)(dippp) (8b)
9.0d
−0.40 (t, 3H, *JHP=4.2, CH3) 0.64 (m, 2H, CH2)
0.80 (m, 2H, CH2)
2.65 (s, 6H, Me)
37.1d
6.86 (t, 1H, 3JHH=7.0, CHar)
7.33 (d, 2H, 3JHH=7.1, CHar)
2JPP=34
0.85 (m, 6H, CH3)
0.90 (m, 2H, CH2)
1.05 (dd, 6H, 3JHP=12.3,
3JHH=6.7, CH3)
1.27 (dd, 6H, 3JHP=15.6,
3JHH=6.5, CH3)
1.47 (dd, 6H, 3JHP=14.7,
3JHH=6.7, CH3)
1.54 (m, 2H, CH)
2.15 (m, 2H, CH)
Ni(CH2CMe2Ph)(OAr)(dippp)
4.6d
1.50 (dd, 2H, 3JHP=4.3, 8.0,
0.55 (pt, 2H, CH2)
2.99 (s, 6H, Me)
(8c)
CH2)

336
J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
Table 2 (Continued)
a
31P{1H}
1H
NiꢀR
PMe3/Pri2P(CH)nPPri2
OAr b
27.9d
1.62 (s, 6H, CMe2)
0.73 (dd, 6H, 3JHP=12.2, 6.79 (t, 1H, 3JHH=7.2, CHar)
3JHH=6.8, CH3)
2JPP=29 6.97 (t, 1H, 3JHP=7.2, CHar)
0.95 (dd, 6H, 3JHP=12.1, 7.31 (d, 2H, 3JHH=7.3, CHar)
3JHH=7.1, CH3)
7.11 (t, 2H, 3JHP=7.8, CHar)
7.43 (d, 2H, 3JHP=7.6, CHar)
0.96 (m, 4H, CH2)
1.15 (dd, 6H, 3JHP=14.6,
3JHH=7.1, CH3)
1.28 (m, 2H, CH)
1.44 (dd, 6H, 3JHP=14.6,
3JHH=7.2, CH3)
2.23 (m, 2H, CH)
C6D6, l en ppm, J en Hz.
a Singlets unless otherwise indicated.
b OArꢁOC5H3ꢀ2,6-Me2.
Pri2PCH2CH2PPri2
was
obtained
by
reacting
Calc. for C16H38NiP2: C, 54.73; H, 10.91. Found: C,
54.84; H, 10.84%.
Cl2PCH2CH2PCl2 with the Grignard Mg(Pri)Cl.
The complex Ni(Me)2(dippp) (3b) was identically pre-
pared and obtained as brown crystals in 53% yield.
Anal. Calc. for C17H40NiP2: C, 55.92; H, 11.04. Found:
C, 56.10; H, 11.09%.
5.1. Synthesis of Ni(CH2SiMe3)2(dippe) (2a)
To a cooled (−80 °C) suspension of NiCl2(py)4
(0.44 g, 1 mmol) in 50 ml of Et2O was added 0.75 ml (9
mmol) of Py and 2.15 ml (2 mmol) of a 0.93 M solution
of Mg(CH2SiMe3)Cl in Et2O. The mixture was allowed
to reach room temperature (r.t.) and stirred for 1 h.
Then it was cooled again at −50 °C, treated with 0.3
ml (1 mmol) of dippe and stirred at r.t. for 2 h. The
solvent was evaporated under reduced pressure and the
residue extracted with 60 ml of petroleum ether. After
centrifugation and partial concentration of the solvent,
cooling to −30 °C provided complex 2a as red crystals
in 63% yield. Anal. Calc. for C22H54NiP2Si2: C, 53.33;
H, 10.98. Found: C, 53.13; H, 10.84%.
5.3. Synthesis of
Ni(CH2SiMe3)(OC6H3ꢀ2,6-Me2)(PMe3)2 (6a)
A suspension of NiCl2(py)4 (0.44 g, 1 mmol) in 50 ml
of Et2O was cooled at −80 °C and Py (0.35 ml, 4.5
mmol) and 2.2 ml (2 mmol) of a 0.93 M solution of
Mg(CH2SiMe3)Cl in Et2O were added. The mixture was
warmed to r.t. and stirred for 2 h, cooled to −80 °C,
and 2 ml (2 mmol) of a 1 M solution of PMe3 in Et2O
were added. The resulting suspension was then stirred
at r.t. for 1 h, during which time the initial red color
due to Ni(CH2SiMe3)2(py)2 turned yellow. The solvent
was evaporated under vacuum and the residue ex-
tracted with 50 ml of Et2O and centrifuged. The solu-
tion was evaporated and the solid, Ni(CH2SiMe3)2-
(PMe3)2 (0.32 g, 0.84 mmol) dissolved in 30 ml of Et2O
and treated with 0.10 g (0.84 mmol) of 2,6-dimethylphe-
nol and stirred at r.t. for 1 h. The solvent was stripped
off and the residue extracted with 30 ml of petroleum
ether and filtered. After partial evaporation of the
solvent and cooling at −30 °C, complex 6a was iso-
lated as yellow crystals in 69% yield. Anal. Calc. for
C18H38NiOP2Si: C, 51.57; H, 9.14. Found: C, 52.12; H,
8.86%.
The compound Ni(CH2SiMe3)2(dippp) (3a) was simi-
larly prepared and isolated as yellow crystals in 65%
yield. Anal. Calc. for C23H56NiP2Si2: C, 54.22; H, 11.08.
Found: C, 54.24; H, 11.37%.
5.2. Synthesis of Ni(Me)2(dippe) (2b)
Pyridine (0.75 ml, 9 mmol) and 1.25 ml (2 mmol) of
a 1.6 M solution of LiMe in Et2O were added to a cold
(−80 °C) suspension of NiCl2(py)4 (0.44 g, 1 mmol) in
Et2O (50 ml). After removing the cold bath the mixture
was stirred at r.t. for 2 h and cooled again at −50 °C
for the addition of 0.3 ml (1 mmol) of dippe. The
suspension was stirred at r.t. for 1 h and then taken to
dryness. The residue was extracted with 50 ml of
petroleum ether and centrifuged. After partial concen-
tration of the solution, cooling to −30 °C furnished
compound 2b as yellow crystals in 55% yield. Anal.
5.4. Synthesis of Ni(Me)(OC6H3ꢀ2,6-Me2)(PMe3)2 (6b)
To a cooled (−20 °C) suspension of NiCl2(PMe3)2
(0.282 g, 1 mmol) in 40 ml of Et2O, were added 0.65 ml

J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
337
Table 3
13C{1H}-NMR data for complexes 6a–c, 7a–c and 8a–c
a
13C{1H}
NiꢀR
PMe3/Pri2P(CH)nPPri2
OAr b
Ni(CH2SiMe3)(OAr)(PMe3)2 (6a)
Ni(Me)(Oar)(PMe3)2 (6b)
−20.4 (t, 2JCP=23, CH2)
2.8 (SiCH3)
12.4 (t, 6C, 1JCP=11, PMe3)
19.3 (s, 2C, Me)
112.2 (s, 1C, CarH)
124.9 (s, 2C, Car)
128.4 (s, 2C, CarH)
165.0 (s, 1C, Car)
23.5 (sa, CH3)
11.5 (sa, 6C, PMe3)
19.1 (s, 2C, Me)
111.8 (s, 1C, CarH)
124.8 (s, 2C, Car)
128.4 (s, 2C, CarH)
166.6 (s, 1C, Car)
Ni(CH2Cme2Ph)(OAr)(PMe3)2 (6c)
10.8 (t, 2JCP=24, CH2)
32.4 (CMe2)
40.2 (CMe2)
124.8 (s, 1C, CarH)
125.6 (s, 2C, CarH)
127.8 (s, 2C, CarH)
153.2 (s, 1C, Car)
12.8 (t, 6C, 1JCP=11, PMe3)
19.5 (s, 2C, Me)
112.2 (s, 1C, CarH)
124.9 (s, 2C, Car)
128.5 (s, 2C, CarH)
165.2 (s, 1C, Car)
Ni(CH2SiMe3)(OAr)(dippe) (7a)
2.17 (dd, 2JCP=31, 67, CH2)
3.8 (SiCH3)
16.6 (dd, 1C, 1JCP=19, 2JCP=11, CH2)
17.8 (s, 2C, CH3)
19.6 (s, 2C, Me)
112.2 (s, 1C, CarH)
125.5 (s, 2C, Car)
128.4 (s, 2C, CarH)
166.5 (s, 1C, Car)
17.9 (s, 2C, CH3)
18.8 (d, 2C, 2JCP=5, CH3)
20.9 (s, 2C, CH3)
23.3 (pt, 1C, *JCP=23, CH2)
23.9 (d, 2C, 1JCP=13, CH)
25.5 (d, 2C, 1JCP=27, CH)
Ni(Me)(OAr)(dippe) (7b)
−0.7 (dd, 2JCP=35, 68, CH3)
16.0 (dd, 1C, 1JCP=19, 2JCP=11, CH2)
18.1 (s, 2C, CH3)
19.2 (s, 2C, Me)
114.2 (s, 1C, CarH)
128.2 (s, 2C, Car)
128.4 (s, 2C, CarH)
165.3 (s, 1C, Car)
18.3 (s, 2C, CH3)
19.0 (d, 2C, 2JCP=5, CH3)
19.5 (d, 2C, 2JCP=3, CH3)
23.6 (d, 2C, 1JCP=13, CH)
23.9 (pt, 1C, *JCP=24, CH2)
25.3 (d, 2C, 1JCP=27, CH)
Ni(CH2CMe2Ph)(OAr)(dippe) c (7c)
26.1 (dd, 2JCP=31, 77, CH2)
32.4 (CMe2)
40.9 (CMe2)
126.1 (s, 2C, CarH)
127.6 (s, 2C, CarH)
127.9 (s, 1C, CarH)
156.1 (s, 1C, Car)
17.0 (dd, 1C, 1JCP=19, 2JCP=10, CH2)
18.3 (sa, 4C, CH3)
19.9 (s, 2C, Me)
111.1 (s, 1C, CarH)
124.5 (s, 2C, Car)
126.3 (s, 2C, CarH)
165.5 (2, 1C, Car)
19.2 (s, 2C, 2JCP=4, CH3)
20.9 (s, 2C, CH3)
23.2 (pt, 1C, *JCP=24, CH2)
23.9 (d, 2C, 1JCP=14, CH)
25.4 (d, 2C, 1JCP=25, CH)
Ni(CH2SiMe3)(OAr)(dippp) (8a)
1.6 (dd, 2JCP=31, 63, CH2)
3.6 (SiCH3)
17.2 (sa, 2C, CH3)
17.5 (m, 2C, CH2)
20.6 (s, 2C, Me)
113.1 (s, 1C, CarH)
125.9 (s, 2C, Car)
128.7 (s, 2C, CarH)
164.5 (2, 1C, Car)
17.7 (sa, 2C, CH3)
19.7 (s, 2C, 2JCP=4, CH3)
20.9 (sa, 2C, CH3)
21.3 (d, 1C, 2JCP=6, CH2)
23.6 (d, 2C, 1JCP=17, CH)
26.4 (d, 2C, 1JCP=28, CH)
Ni(Me)(OAr)(dippp) (8b)
1.20 (dd, 2JCP=38, 61, CH3)
17.6 (s, 2C, CH3)
17.9 (m, 2C, CH2)
19.2 (s, 2C, Me)
114.3 (s, 1C, CarH)
128.1 (s, 2C, CarH)
128.5 (s, 2C, Car)
164.2 (s, 1C, Car)
18.1 (s, 2C, CH3)
19.8 (d, 2C, 2JCP=5, CH3)
21.2 (d, 2C, 2JCP=3, CH3)
22.3 (m, 1C, CH2)
24.0 (d, 2C, 1JCP=16, CH)
26.3 (d, 2C, 1JCP=29, CH)
C6D6, l en ppm, J en Hz.
a Singlets unless otherwise indicated.
b OArꢁOC5H3ꢀ2,6-Me2.
c CD2Cl2 (−30 °C).

338
J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
Scheme 4.
extracted with Et2O (40 ml) and centrifuged. The
solution was evaporated under vacuum, and the
resulting solid residue, Ni(Me)Cl(PMe3)2 (0.23 g, 0.88
mmol) dissolved in 30 ml of Et2O and the solution
cooled at −50 °C and treated with 1.2 ml (0.88 mmol)
of a 0.74 M solution of Na(2,6-OC6H3Me2) in THF.
The mixture was allowed to reach r.t. and stirred for 1
h. The solvent was evaporated under reduced pressure
and the residue extracted with 45 ml of Et2O. The
Scheme 3.
(1 mmol) of a 1.6 M solution of LiMe in Et2O. The
mixture was stirred 30 min at this temperature, 45 min
at r.t. and then taken to dryness. The residue was
Table 4
31P{1H}-, 1H- and 13C{1H}-NMR data for complexes 9 and 10
31P{1H} 1H
13C{1H}
NiꢀR
Pri2P(CH)nPPri2
NiꢀR
Pri2P(CH)nPPri2
¸¹¹¹¹¹¹¹¹º
Ni(CH2CMe2-o-C6H4)-
(dippe) (9)
68.1d
71.5d
2.01 (dd, 2H, 3JHP=3.2,
9.9, CH2)
0.86 (m, 12H,
CH3)
46.1 (dd, 2JCP=18,
61, CH2)
35.8 (d, 4JCP=4,
CMe2)
18.4 (d, 2C, 2JCP=6, CH3)
1.74 (s, 6H, CMe2)
1.06 (m, 12H,
CH3)
19.2 (d, 2C, 2JCP=5, CH3)
20.3 (m, 2C, CH2)
20.6 (s, 2C, CH3)
2JPP=5 7.29 (m, 3H, CHar)
1.09 (m, 4H, CH2) 51.2 (d, 3JCP=5,
CMe2)
7.77 (t, 1H, 3JHH=6.2,
1.85 (h, 2H, CH)
121.8 (s, CarH)
CHar)
2.09 (h, 2H, CH)
122.9 (d, JCP=6,
CarH)
20.7 (s, 2C, CH3)
123.2 (s, CarH)
140.8 (dd, JCP=4,
9, CarH)
24.7 (d, 2C, 2JCP=19, CH)
25.1 (d, 2C, 2JCP=13, CH)
167.7 (dd, 2JCP=15,
81, Car)
168.6 (d, 3JCP=5,
Car)
¸¹¹¹¹¹¹¹¹º
Ni(CH2CMe2-o-C6H4)-
(dippp) (10)
21.1d
19.1d
1.83 (dd, 2H, 3JHP=2.2,
10.6, CH2)
0.90 (m, 12H,
CH3)
0.98 (m, 2H, CH2) 35.3 (d, 4JCP=4,
CMe2)
1.19 (m, 14H,
CH3, CH2)
1.42 (m, 2H, CH2) 121.8 (s, CarH)
47.8 (dd, 2JCP=20,
58, CH2)
16.7 (dd, 1C, 1JCP=13,
2JCP=9, CH2)
1.77 (s, 6H, CMe2)
17.7 (d, 2C, CH3)
2JPP=23 7.26 (m, 3H, CHar)
50.8 (t, *JCP=4,
CMe2)
17.8 (s, 2C, CH3)
7.77 (t, 1H, 3JHH=6.7,
CHar)
19.0 (dd, 1C, 1JCP=11,
2JCP=5, CH2)
1.92 (h, 2H, CH)
2.25 (h, 2H, CH)
122.8 (d, JCP=6,
CarH)
20.0 (d, 2C, 2JCP=5, CH3)
123.1 (s, CarH)
138.7 (dd, JCP=5,
9, CarH)
21.2 (t, 1C, 2JCP=4, CH2)
21.5 (d, 2C, 2JCP=9, CH3)
166.9 (dd, 2JCP=18, 25.2 (d, 2C, 1JCP=14, CH)
74, Car)
168.0 (d, 3JCP=5,
25.8 (d, 2C, 1JCP=20, CH)
Car)
C6D6, l en ppm, J en Hz.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
339
Scheme 5.
suspension was centrifuged and the solution partially
evaporated and cooled to −30 °C. Compound 6b was
obtained as yellow crystals in 65% yield. Anal. Calc. for
C15H30NiOP2: C, 51.91; H, 8.71. Found: C, 51.76; H,
8.35%.
7a: Anal. Calc. for C26H52NiOP2Si: C, 58.99; H, 9.90.
Found: C, 58.55; H, 10.01%.
7b: Anal. Calc. for C23H44NiOP2: C, 60.42; H, 9.70.
Found: C, 60.67; H, 9.82%.
7c: Anal. Calc. for C32H54NiOP2: C, 66.79; H, 9.46.
Found: C, 66.24; H, 9.38%.
8a: Anal. Calc. for C27H54NiOP2Si: C, 59.67; H,
10.02. Found: C, 58.97; H, 10.24%.
8b: Anal. Calc. for C24H46NiOP2: C, 61.17; H, 9.84.
Found: C, 60.73; H, 9.80%.
5.5. Synthesis of
Ni(CH2CMe2Ph)(OC6H3ꢀ2,6-Me2)(PMe3)2 (6c)
A suspension of NiCl2(PMe3)2 (0.56 g, 2 mmol) in
Et2O (80 ml) was cooled at −50 °C and 2.22 ml (2
mmol) of a 0.9 M solution of Mg(CH2CMe2Ph)Cl in
Et2O was added. The mixture was warmed to r.t. and
stirred for 5 h. The solvent was evaporated under
vacuum and the residue extracted with 40 ml of Et2O
and centrifuged. The solution was evaporated and the
solid residue, compound Ni(CH2CMe2Ph)Cl(PMe3)2
(0.62 g, 1.65 mmol) dissolved in 30 ml of Et2O and the
solution cooled at −50 °C and Na(2,6-OC6H3Me2)
(1.65 mmol, 2.4 ml of a 0.74 M solution in THF)
added. The resulting suspension was stirred at r.t. for 2
h and then taken to dryness. The residue was extracted
with 60 ml of petroleum ether and the solution filtered.
After partial concentration of the solvent, cooling to
−30 °C provided compound 6c as yellow crystals in
50% yield. Anal. Calc. for C24H40NiOP2: C, 61.96; H,
8.67. Found: C, 61.32; H, 8.67%.
The preparation of compounds 7a–c and 8a–c in-
volves the reaction of Ni(R)(2,6-OC6H3Me2)(PMe3)2
(R=CH2SiMe3, Me, CH2CMe2Ph) with the appropri-
ate phosphine, dippe or dippp. A representative exam-
ple of the experimental procedure employed to
synthesize 7b is as follows.
Dippe (0.15 ml, 0.5 mmol) was added to a cooled
(−50 °C) solution of complex 6b (0.18 g, 0.5 mmol) in
Et2O (40 ml). After removing the cold bath, the mixture
was stirred at r.t. for 1 h. The solvent was evaporated
under reduced pressure and the residue extracted with
30 ml of petroleum ether. After partial concentration of
the solvent and cooling to −30 °C, compound 7b was
isolated as yellow crystals in quantitative yield.
8c: Anal. Calc. for C33H56NiOP2: C, 67.24; H, 9.58.
Found: C, 66.61; H, 9.95%.
5.6. Synthesis of N¸i(¹C¹H¹2C¹M¹¹e2¹-o¹-ºC6H4)(dippe) (9)
5.6.1. Method a
A solution of complex 7c (0.29 g, 0.5 mmol) in 20 ml
of THF was stirred at r.t. for 12 h. The solvent was
Table 5
,
Selected bond lengths (A) and angles (°) for compound 7a
Bond lengths
Ni(1)ꢀP(1)
Ni(1)ꢀP(2)
Ni(1)ꢀO(1)
2.225(3)
2.122(5)
1.907(8)
Ni(1)ꢀC(9)
Si(1)ꢀC(9)
O(1)ꢀC(1)
2.001(10)
1.855(10)
1.32(1)
Bond angles
P(1)ꢀNi(1)ꢀP(2) 88.52(14)
P(1)ꢀNi(1)ꢀO(1) 88.9(2)
P(2)ꢀNi(1)ꢀC(9) 91.3(4)
O(1)ꢀNi(1)ꢀC(9)
Ni(1)ꢀO(1)ꢀC(1)
Ni(1)ꢀC(9)ꢀSi(1)
91.0(4)
135.0(7)
115.1(5)
Table 6
,
Selected bond lengths (A) and angles (°) for compound 8a
Bond lengths
Ni(1)ꢀP(1)
Ni(1)ꢀP(2)
Ni(1)ꢀO(1)
2.151(5)
2.264(3)
1.915(7)
Ni(1)ꢀC(9)
O(1)ꢀC(1)
Si(1)ꢀC(9)
1.988(9)
1.309(10)
1.858(9)
Bond angles
P(1)ꢀNi(1)ꢀP(2) 97.36(13)
P(1)ꢀNi(1)ꢀC(9) 89.8(3)
P(2)ꢀNi(1)ꢀO(1) 85.1(2)
O(1)ꢀNi(1)ꢀC(9)
Ni(1)ꢀO(1)ꢀC(1)
Ni(1)ꢀC(9)ꢀSi(1)
87.8(3)
133.1(6)
116.8(5)

340
J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
Table 7
yield. Anal. Calc. for C24H44NiP2: C, 64.26; H, 9.92.
Found: C, 64.10; H, 9.61%.
Crystal and refinement data for compounds 7a and 8a
7a
8a
5.7. Reactions of compounds 7a–c and 8a–c with CO
Empirical formula
Molecular weight
Temperature (K)
C26H52NiOP2Si
529.42
290
C
543.46
290
0.71069
Red prism
Orthorhombic
P212121 (No.
19)
27H54NiOP2Si
The carbonylation of complexes 7a–c and 8a–c gives
rise to the formation of carbonyls Ni(CO)2(dippe) (or
Ni(CO)2(dippp)) and the organic esters RCO2C6H3ꢀ2,6-
Me2 (R=Me, CH2CMe2Ph), as a result of the reduc-
tive elimination reaction. An example of the reaction of
complex 7b is as follows.
,
u (A) (Mo–Ka)
0.71069
Color and habit
Crystal system
Space group
Orange plate
Orthorhombic
P212121 (No. 19)
Unit cell dimensions
CO was bubbled through a solution of compound 7b
(0.23 g, 0.5 mmol) in 20 ml of Et2O at r.t. for 5 min (a
1H-NMR spectrum of the crude mixture showed quan-
titative conversion to the products). The resulting col-
orless solution was evaporated and the oily residue
extracted with Et2O and filtered. From the filtrate, ester
13b was isolated by spinning band chromatography,
using the mixture petroleum ether–Et2O (9.5:0.5) as
eluant.
,
a (A)
17.210(4)
18.080(4)
9.600(4)
2987(2)
4
17.704(4)
18.347(4)
9.475(3)
3077(2)
4
,
b (A)
,
c (A)
V (A )
3
,
Z
Dcalc (g cm−3
Diffractometer
)
1.177
1.173
MSC-Rigaku
AFC6S
Graphite
0.81
0.15×0.25×0.37
ꢀ–2q
MSC-Rigaku
AFC6S
Graphite
0.79
0.14×0.17×0.26
ꢀ–2q
Monochromator
v (mm−1
)
Crystal size (mm)
Scan type
2q range (°)
Decay (three standards
every 100 reflections)
(%)
5.7.1. MeCO2C6H3ꢀ2,6-Me2
5.0–50.1
−1.30
5.0–50.1
−0.71
1H-NMR (C6D6, 20 °C) l 1.82 (s, 3H, Me), 2.03 (s,
6H, Me2), 6.89 (s, 3H, CHar); 13C{1H} (C6D6, 20 °C) l
15.9 (s, Me), 19.5 (s, Me2), 125.6 (s, CarH), 128.5 (s,
CarH), 130.3 (s, Car), 152.9 (s, Car), 168.0 (s, CO).
EI–HRMS: m/z 164.08372 [M+] (exact mass calculated
for C10H12O2 164.08373).
Absorption correction
ƒ-scan, 0.95–1.00 ƒ-scan,
0.97–1.00
2666
(Fmin, Fmax
No. of reflections
No. of refined parameters 280
)
2576
289
R factor all
R factor [I\2|(I)]
wR
wR [I\2s(I)]
Goodness-of-fit
0.0980
0.1125
0.0483
0.1365
0.1142 b
0.964
0.0499
0.1775
0.1310 a
1.045
5.7.2. PhMe2CCH2CO2C6H3ꢀ2,6-Me2
1H-NMR (C6D6, 20 °C) l 1.40 (s, 6H, Me2), 1.87 (s,
6H, Me2), 2.68 (s, 2H, CH2), 6.85 (s, 3H, CHar), 7.05 (t,
3
3
1H, JHH=7.3 Hz, CHar), 7.15 (t, 2H, JHH=7.7 Hz,
CHar), 7.26 (d, 2H, 3JHH=7.6 Hz, CHar); 13C{1H}
(C6D6, 20 °C) l 16.1 (s, CMe2), 29.0 (s, CMe2), 36.8 (s,
CMe2), 47.0 (s, CH2), 125.4, 125.7, 126.0, 128.2, 128.4
(s, CarH), 130.2, 147.8, 148.7 (s, Car), 168.3 (s, CO).
EI–HRMS: m/z 282.1617 [M+] (exact mass calculated
for C19H22O2 282.16198).
a w=1/[|2(Fo2)+(0.1057P)2]; P=([Fo]2+2[Fc]2)/3.
b w=1/[|2(Fo2)+(0.0557P)2]; P=([Fo]2+2[Fc]2)/3.
evaporated under vacuum, the residue extracted with
Et2O (25 ml) and the solution filtered. The filtrate was
concentrated and some petroleum ether added. Cooling
to −30 °C furnished complex 9 as orange crystals in
94% yield. Anal. Calc. for C24H44NiP2: C, 63.60; H,
9.78. Found: C, 63.63; H, 10.01%.
5.8. X-ray structure determination of compounds 7a
and 8a
A summary of crystal and refinement data is reported
in Table 7. Data were collected on a MSC-Rigaku
AFC6S diffractometer and corrected for absorption
and Lorentz-polarization effects. The structures were
solved by Patterson method using TEXSAN, Single Crys-
tal Structure Analysis Software [20]. Refinements were
performed using SHELXL-97 program [21]. In both
structures all non-hydrogen atoms were anisotropically
refined. The hydrogen atoms were treated by the SHELX
riding model. Calculations for data reduction and
structure solution were performed on a VAX 3520
station at the ‘Servicio Central de Ciencia y Tecnolog´ıa
de la Universidad de Ca´diz’.
5.6.2. Method b
A solution of complex 11 (0.17 g, 0.5 mmol) in 30 ml
of Et2O was cooled at −30 °C and 0.15 ml (0.5 mmol)
of dippe were added. The mixture was stirred at r.t. for
1 h. The solvent was stripped off and the residue
extracted with 20 ml of Et2O. After filtration, partial
evaporation of the solvent and cooling to −30 °C,
compound 9 was obtained as orange crystals in quanti-
tative yield.
¸¹¹¹¹¹¹¹¹º
Complex Ni(CH2CMe2-o-C6H4)dippp (10) was simi-
larly prepared and isolated as red crystals in quantitave

J. Ca´mpora et al. / Journal of Organometallic Chemistry 643–644 (2002) 331–341
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Acknowledgements
Financial support from the Direccio´n General de
Ensen˜anza Superior e Investigacio´n Cient´ıfica (M.E.C)
(Research grant to C.M. and Project 1FD97-019-C02-
01), Direccio´n General de Investigacio´n (M.C.T.) (Pro-
ject BQU2000-1169) and Junta de Andaluc´ıa is
gratefully acknowledged. J.A.L. thanks the CONACYT
and the University of Guanajuato (Mexico) for a
fellowship.
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