Monomeric alkoxo and amido methylnickel(II) complexes. Synthesis and heterocumulene insertion chemistry

Article abstract of DOI:10.1021/om7002909

Fluoride displacement from the complex Ni(Me)(F)(dippe) by LiOR or LiNRR′ provides an efficient method for the synthesis of the corresponding mononuclear Ni(II) alkoxo or amido complexes. These complexes undergo addition reactions to heterocumulenes (CO₂, PhNCO, PhNCS), leading to the formal insertion of these molecules into the Ni-O or Ni-N bonds. The dialkylamido complexes decompose through β-hydrogen elimination processes, which selectively afford η²-imine Ni(O) compounds.

Full text of DOI:10.1021/om7002909

3840
Organometallics 2007, 26, 3840-3849
Monomeric Alkoxo and Amido Methylnickel(II) Complexes.
Synthesis and Heterocumulene Insertion Chemistry
Juan Ca´mpora,*,† Inmaculada Matas,† Pilar Palma,† Eleuterio AÄ lvarez,† Claudia Graiff,‡ and
Antonio Tiripicchio‡
Instituto de InVestigaciones Qu´ımicas, Consejo Superior de InVestigaciones Cient´ıficas-UniVersidad de
SeVilla. AVenida Ame´rico Vespucio 49, 41092 SeVilla, Spain, and Dipartamento di Chimica Generale ed
Inorganica, Chimica Analitica, Chimica Fisica, UniVersita` di Parma, Viale G.P. Usberti 17/A,
I-43100 Parma, Italy
ReceiVed March 27, 2007
Fluoride displacement from the complex Ni(Me)(F)(dippe) by LiOR or LiNRR′ provides an efficient
method for the synthesis of the corresponding mononuclear Ni(II) alkoxo or amido complexes. These
complexes undergo addition reactions to heterocumulenes (CO2, PhNCO, PhNCS), leading to the formal
insertion of these molecules into the Ni-O or Ni-N bonds. The dialkylamido complexes decompose
through â-hydrogen elimination processes, which selectively afford η2-imine Ni(0) compounds.
droxide, tert-butoxide, or pyrrolidinide is greatly improved when
X ) F. However, while the hydroxide complex could be
structurally characterized, the thermal instability of the tert-
butoxide and pyrrolidinide derivatives prevented their isolation.
In this contribution we extend the scope of our synthetic
methodology, reporting the synthesis, isolation, and structural
characterization of new alkoxo and amido complexes of nickel
of the type Ni(Me)(OR)(dippe) and Ni(Me)(NRR′)(dippe) (R,
R′ ) alkyl). The latter are highly unusual compounds since most
of the available examples of group 10 amido complexes are
currently limited to arylamides,3c,6 silylamides,7 and the parent
Introduction
Late transition metal complexes displaying covalent, nonda-
tive M-X bonds, where X is a hard heteroatom donor (F, OR,
NR2), have received much attention in recent years1 because of
their implication as reactive intermediates in important catalytic
transformations.1b,2 Their strongly basic and nucleophilic reac-
tivity has been interpreted as a result of the strong polarization
of the M-X bond and the absence of important π metal-ligand
(p-d) interactions.3
As a continuation of our current work on Ni and Pd
complexes displaying covalent M-O and M-N bonds,4 we
have recently communicated5 that the synthesis of the corre-
sponding hydroxo, alkoxo, and amido derivatives from a Ni-
4a
amidonickel complex (PCPiPr)Ni-NH2 (PCPiPr ) C6H3-2,6-
(CH2PiPr2)2). In addition, we explore the reactivity of those
complexes toward heterocumulenes (CO2, PhNCO, and PhNCS),
a reaction that has been used as a probe to gauge the
nucleophilicity of metal alkoxo and amido complexes.1d,6a,8
i
(Me)(X)(dippe) (dippe ) Pr2PCH2CH2PiPr2) and lithium hy-
* Corresponding author. E-mail: campora@iiq.csic.es.
† Consejo Superior de Investigaciones Cient´ıficas-Universidad de
Sevilla.
Results and Discussion
‡ Universita` di Parma.
Synthesis and Characterization of Ni Alkoxo and Amido
Complexes. Transition metal alkoxides and amides are usually
prepared by simple halide metathesis reactions with the corre-
sponding alkaline derivatives,9 but this method often proves
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10.1021/om7002909 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 06/20/2007

Monomeric Alkoxo and Amido Methylnickel(II) Complexes
Organometallics, Vol. 26, No. 15, 2007 3841
Scheme 1
Scheme 2
difficult in the case of the late transition elements.1a One of the
most frequent alternatives to this procedure is to replace halide
by a weakly coordinated ligand that can be easily displaced,
such as triflate.3c With the aim of developing a general method
for the synthesis of monomeric nickel complexes displaying a
chelating diphosphine and mutually cis alkyl and alkoxo and
amido compounds, we have investigated the reaction of the
methyl complexes Ni(Me)(X)(dippe) (X ) Cl (1a), OTf (1b),
and F (1c)) with alkaline hydroxides, alkoxides, and amides.
The chloro and fluoro complexes are prepared in good yields
from NiMe2(dippe)10 upon reaction with NMe3‚HCl and NEt3‚
3HF, respectively, as we reported in preliminary form.5 Simi-
larly, the triflate 1b was generated in THF solution by reaction
with HOTf and used directly. The 31P{1H} spectrum of the
reaction mixture showed that 1b is cleanly formed (two
resonances at δ 65.6 and 77.8 ppm), but attempts to isolate the
product were complicated by partial hydrolysis to the dinuclear
hydroxide [Ni(µ-OH)(dippe)2]2+(OTf-)2, 2.11 Po¨rschke has
prepared related triflate [Ni(Me)(OTf)(dtbpe)] (dtbpe ) 1,2-
(di-tert-butyl)phosphino)ethane) following a similar procedure.12
Preliminary exploration of 1a and 1b as starting materials in
ligand metathesis reactions was not satisfactory and did not
allow the isolation of the desired hydroxo or alkoxo products.
Thus, the chloro precursor 1a does not react with sodium or
lithium hydroxide in THF and upon exposure to MOtBu (M )
Li, K) undergoes incomplete chloride displacement. The reaction
of 1b with lithium hydroxide is more complex and leads to a
mixture of 2 and a new product, tentatively formulated as the
that typically soft, late transition metals such as Pt display only
slightly less affinity for the hard fluoride anion than for the
heavier halides.16 In Co and Rh complexes, this affinity
decreases in the order F > Cl > Br > I.17 Therefore, it seems
likely that the driving force for this reaction is not the
(presumed) weakness of the late transition metal-fluoride bond,
but the formation of the very stable salt LiF. The contribution
of this factor to the overall energy balance of the reaction can
be estimated as ca. 200-300 kJ mol-1, if the lattice energy of
LiF, 1030 kJ mol-1, is compared to that of LiCl (834 kJ mol-1),
NaCl (769 kJ mol-1), or KCl (701 kJ mol-1).18
As represented in Scheme 2, we have successfully extended
this strategy to the synthesis of a number of new alkoxo (7-9)
and amido complexes (10-12). Direct monitoring of the reaction
of 1c with the corresponding lithium alkoxides and amides
shows that these transformations also take place in a very
selective manner, affording a single product in each case,
together with a precipitate of insoluble LiF.
In contrast to the thermally unstable tert-butoxide 5, the
alkoxides 7-9 could be obtained as crystalline orange solids,
in 45, 62, and 58% isolated yield, respectively. They have been
fully characterized by elemental analysis and NMR. Apart from
the expected signals of the OR group, these spectra are very
similar to those of the hydroxide 4. For example, their 31P{1H}
spectra display characteristic AX spin systems with δA ≈ 64
and δX ≈ 75 ppm and JAX ) 7-11 Hz. In addition, the
methoxide 7 has been subjected to an X-ray diffraction study,
as the number of structurally characterized monomeric alkoxides
of Ni is small.3c,4a,19
1
dinuclear hydroxide 3 on the basis of its H NMR spectrum,
which displays characteristic OH (δ -2.28) and CH3 (δ 0.39)
resonances with 1:6 intensity ratio (Scheme 1). Several dinuclear
Pd and Pt complexes bridged by a single hydroxide ligand are
known.13 These results suggest that, while chloride displacement
by hydroxide or alkoxide ligands is a difficult process on the
coordination sphere of nickel, the lability of the triflate group
favors the formation of kinetically stable dinuclear species,
complicating the outcome of the exchange reaction.
An ORTEP representation of one of the two independent
molecules found in the asymmetric unit (which display no
significant differences) is shown in Figure 1, together with some
selected bond distances and angles. The molecule displays a
slightly distorted square-planar structure, with the Ni-O-CH3
fragment lying nearly coplanar with the mean coordination plane
(dihedral angle, 17.1(3)°). As it is often found in late transition
metal alkoxides,1a,20 the C-O bond length (1.345(4) Å) is
somewhat shorter than the standard C-O bond (1.43 Å).
Although this C-O bond shortening has been connected with
the tendency of alkoxides to decompose via â-hydride elimina-
In contrast with 1a and 1b, the fluoride precursor 1c proved
to be a valuable starting material for the synthesis of the desired
products. Monitoring the reactions of this compound with LiOH,
LiOtBu, and LiNC4H8 in THF by 31P{1H} NMR showed them
to proceed cleanly with quantitative transformation of 1c into
the corresponding hydroxo (4), alkoxo (5), and amido (6)
derivatives (Scheme 2).5 Late transition metal fluoride com-
plexes are reactive compounds14 that display higher basicity or
nucleophilicity than the related halides,15 but it has been shown
(10) This compound is readily obtained from NiCl2(dippe) and LiMe
(see Experimental Section). Its synthesis from NiMe2(pyridine)2 and dippe
has been reported before: Ca´mpora, J.; Lo´pez, J. A.; Maya, C.; Palma, P.;
Carmona, E.; Valerga, P. J. Organomet. Chem. 2002, 643, 331.
(11) Lo´pez, J. A. Ph.D. Thesis, University of Sevilla, 1999.
(12) Bach, I.; Goddard, R.; Kopiske, C.; Seevogel, K.; Po¨rschke, K. R.
Organometallics 1999, 18, 10.
(13) (a) Klein, A.; Dogan, A.; Feth, M.; Bertagnolli, H. Inorg. Chim.
Acta 2003, 343, 189. (b) Suzaki, Y.; Osakada, K. Organometallics 2004,
23, 5081. (c) Yoshida, T.; Tanaka, S.; Adachi, T.; Yoshida, T.; Onitsuka,
K.; Sonogashira, K. Angew. Chem., Int. Ed. 1995, 34, 319.
(14) Grushin, V. V.; Marshall, W. J. J. Am. Chem. Soc. 2004, 126, 3068.
(15) Archibald, S. J.; Braun, T.; Gaunt, J. A.; Hobson, J. E.; Perutz, R.
N. J. Chem. Soc., Dalton Trans. 2000, 2013.
(16) Nilsson, P.; Plamper, F.; Wendt, O. F. Organometallics 2003, 22,
5235.
(17) Araghizadeh, F.; Branan, D. M.; Hoffman, N. W.; Jones, J. H.;
McElroy, A.; Millar, C.; Ramaje, D. L.; Battaglia Salazar, A.; Young, S.
H. Inorg. Chem. 1988, 27, 3752.
(18) Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca
Raton, FL, 2003; pp 12-22.
(19) Jian, P. M.; Wang, S. X.; Suo, J. S.; Wang, L. F.; Wu, Q. G. Acta
Crystallogr. Sect. C: Cryst. Struct. Commun. 1995, 51, 1071.
(20) Alsters, P. L.; Boersma, J.; Smeets, W. J. J.; Spek, A. L.; van Koten,
G. Organometallics 1993, 12, 1639.

3842 Organometallics, Vol. 26, No. 15, 2007
Ca´mpora et al
Figure 1. ORTEP view of 7. Selected bond lengths (Å) and angles
(deg) (one of two independent molecules in the asymmetric unit):
Ni(1)-O(1), 1.878(2); Ni(1)-C(1), 1.954(2); Ni(1)-P(1), 2.1264-
(7); Ni(1)-P(2), 2.1911(7); O(1)-C(2), 1.345(4); O(1)-Ni(1)-
C(1), 94.27(10); C(1)-Ni(1)-P(1), 91.20(16); O(1)-Ni(1)-P(2),
88.60(14); P(2)-Ni(1)-P(1), 89.22(6); Ni(1)-O(1)-C(2), 125.8-
(2).
Figure 2. ORTEP view of 12. Selected bond lengths (Å) and angles
(deg): Ni(1)-N(1), 1.860(3); Ni(1)-C(1), 1.977(3); Ni(1)-P(1),
2.1248(8); Ni(1)-P(2), 2.2056(8); N(1)-C(16), 1.459(4); N(1)-
Ni-C(1), 92.15(13); C(1)-Ni(1)-P(1), 87.87(10); N(1)-Ni(1)-
P(2), 91.23(9); P(2)-Ni(1)-P(1), 88.78(3); C(16)-N(1)-Ni(1),
133.1(2); C(16)-N(1)-H(1N), 120.2; Ni(1)-N(1)-H(1N), 106.7.
tion,21 it has also been explained as a result of a Coulombic
attractive interaction between the carbon and oxygen atoms of
the strongly polarized O-C functionality.22 In any case, this
bond contraction is less pronounced in complex 7 than in the
related compounds Ni(PCPiPr)(OMe)4a and Ni(η5-C5Me5)(PEt3)-
(OMe).3c Other bond distances in this molecule can be consid-
ered normal for this kind of complexes. Thus, the Ni-O bond
distance, 1.878(2) Å, is almost identical to that of hydroxide
complex 4, 1.877(4) Å. The methoxide and hydroxide ligands
exert a similar trans influence, as indicated by the similar values
of the (NiP1)-(NiP2) bond length differences (0.057 Å in 4
and 0.065 Å in 7).
in the methyne resonance of 12. The NH signal cannot be
directly observed in the H spectra of 11 and 12 because it is
1
obscured by the intense resonances of the diphosphine ligand,
but the coupling to the methylene or methyne protons allowed
it to be located at ca. δ 1.1 ppm in the COSY spectra. There is
also a difference in the 13C{1H} N-CH2 signals of the diben-
zylamide complex (δ 60.0, s) and the monobenzylamide, which
appears ca. 8 ppm upfield (δ 51.7 ppm). The 13C resonances of
the N-bound carbon atoms of the two primary amides show
couplings of 5 Hz with one phosphorus nucleus, which is not
observed in the case of 10. As shown below, secondary amides
are very prone to undergo â-hydrogen elimination, while the
decomposition of the primary derivatives involves a more
complex process, apparently involving both â-elimination and
disproportionation routes.5 The small but noticeable differences
observed in the NMR spectra of the two kinds of complexes
suggest that the primary and secondary amido groups could
adopt different conformations in solution, which could be
connected to their different thermal behavior.
The lithium fluoride displacement reaction also proves useful
in the synthesis of a range of secondary and primary amido
complexes, including the previously reported pyrrolidinide 6.
The hydrolytic sensitivity and high solubility in hydrocarbon
solvents thwarted the isolation of crystalline samples of 6, 10,
and 11. In addition, these compounds gradually decompose at
room temperature, making it difficult to gather spectroscopic
data. In spite of this, full NMR data (1H, 13C, and 31P) have
been obtained for complexes 10-12, which confirm the
proposed structures. Interestingly, the spectra of the primary
and secondary amide complexes display some differences. For
example, the 31P{1H} spectrum of 10 is fairly similar to that of
6, both of them displaying two signals at ca. δ 50 and 69 ppm,
The lower solubility of compound 12 allowed the growth of
dark red crystals from a concentrated pentane solution at
-20 °C, which proved suitable for X-ray diffraction. The crystal
structure of this compound is given in Figure 2. As can be
immediately noticed, the amido ligand adopts a remarkable
configuration. In contrast with most square-planar complexes,
where bulky ligands tend to orient perpendicular to the
coordination plane in order to minimize steric repulsions, the
alkyl chain of the primary amido group lies almost exactly in
the plane, bringing the N-C bond to the syn-periplanar position
relative to the Ni-C bond, with a Me-Ni-N1-C16 dihedral
angle of 1.1(4)°. Furthermore, the amine H atom has been
located in a position that strongly suggests a planar configuration
of the N atom. These features are strongly reminiscent of those
found in Ni(NH2)(PCPiPr), which also displays a coplanar and
apparently flat NH2 group.4a Noteworthy, the metal-nitrogen
bond (1.860(3) Å) is somewhat short compared to covalent
Ni-N bonds in arylamides6 (1.932 Å), amidates6 (Ni-N(R)C-
2
with negligible JPP constants. In contrast, the corresponding
31P{1H} signals for the primary amides 11 and 12 occur at δ
69 and 78 ppm, with a noticeable coupling of ca. 5 Hz. The 1H
and 13C{1H} spectra of the four compounds display the expected
signals for the amido and methyl fragments. Only one 1H signal
is observed for the non-diastereotopic benzyl methylene protons
of 10 and 11, but in the former this signal appears as a singlet
at δ 4.10 ppm, while in the latter compound, it is shifted to
lower field (δ 4.62 ppm) and split into a doublet of doublets by
couplings with one of the 31P (JHP ) 4 Hz) nuclei and the NH
proton (JHH ) 7.5 Hz). The same couplings are also observed
(21) Alcock, N. W.; Platt, A. W. G.; Pringle, P. J. Chem. Soc., Dalton
Trans. 1987, 2273.
(22) Wiberg, K. B. M. J. Am. Chem. Soc. 1990, 112, 3379.

Monomeric Alkoxo and Amido Methylnickel(II) Complexes
Organometallics, Vol. 26, No. 15, 2007 3843
Scheme 3
Figure 3. η2-Imine complexes of Ni(0) 13 and 14.
coordination of the imine introduces asymmetry in these
molecules, causing chemical inequivalence of all four iPr groups
of the diphosphine as well as the methylene protons, which
become diastereotopic. However, while the 1H spectrum of 14
is sharp at room temperature, that of the pyrroline complex
appears broad, gaining normal resolution below -20 °C (at 300
MHz). Heating above room temperature (35-45 °C) causes the
signals of each pair of diastereotopic methylene protons to
coalesce, while the complex pattern of the diphosphine ligand
resonances simplifies. At the same time, the 31P{1H} spectrum
becomes broader, but the fast exchange limit could not be
reached because the complex decomposes above 55 °C. The
energy barrier associated with this fluxional process can be
estimated to amount to 15.5 kcal mol-1 on the basis of the
coalescence temperatures of the methylenic signals. The ap-
parent symmetrization of the molecule can be explained by a
rapid, reversible dissociation of the η2-imine ligand from nickel.
However, since 1-pyrroline is known to be an unstable
molecule,26 it is likely that such dissociation is only partial,
consisting in the exchange between the η2 and η1 coordination,
as shown in Scheme 3. The readiness of the imine ligand motion
in 13 contrasts with the nonfluxional behavior of the similar
complex 14. Although there is no obvious reason for this
difference, the mobility of the pyrroline ligand is likely to be
facilitated by the lack of steric hindrance at the nitrogen atom.
The unusual dynamic behavior of complex 13 prompted us
to confirm its structure by an X-ray diffraction study. Its crystal
structure is shown in Figure 4. The formally three-coordinated
complex displays the nickel atom in an approximately trigonal-
planar environment, with the imine ligand occupying one of
the coordination positions in the expected side-on coordination
mode. The C-N bond distance (1.352(3) Å) is appreciably
shorter than in a recently reported η2-imine Ni(I) complex
(1.435 Å).26 This is somewhat surprising, as the strongly
electron-back-donating Ni(0) center is expected to decrease the
CdN bond order more efficiently than Ni(I). The CdN bond
lengths in the other two Ni(0)-η2-imine complexes are only
slightly longer than that of 13.28
(O)R′ (ca. 1.98 Å), and pyrrolides23 and other heterocyclic
derivatives24 (1.88-1.95 Å), or even in the parent amide Ni-
NH2 (1.872 Å).4a
Planar nitrogen amido groups have been previously observed
in group 10 arylamides,6,25 but these display distinctly short
N-C bonds, a feature that has been attributed to π delocalization
of the nitrogen lone pair in the aromatic ring. In the case of
aliphatic amides, planarity could arise from a hyperconjugative
interaction of the nitrogen lone pair with empty σ* orbitals of
adjacent C-H or C-C bonds. However, the N-C distance in
12 (1.459(4) Å), similar to the standard value in aliphatic amines
(ca. 1.45 Å), offers little support for such an effect. On the other
hand, although the relatively short Ni-N could suggest the
existence of some ligand to metal pπ-dπ donation, this is
unlikely, as the only empty d orbital in the square-planar d8
2
2
center (dx -y ) lacks the adequate symmetry for an in-plane π
interaction with the amido group. In fact the Ni-N distance,
albeit relatively short, is appreciably longer than in the formally
14 e, tricoordinated amide Ni(NH-C6H3 Pr2-2,6)(dtbpe)+
i
(1.768 Å), where such a π interaction becomes more likely.6b
Therefore, we cannot offer a satisfactory explanation for the
unusual conformation of the alkylamido group. However, the
similar, nearly coplanar configuration of the methoxide group
in 7 suggests that similar effects may be at play in both
compounds. In fact, both complexes display very similar Ni-P
bonds, indicating that these sense similar influences from the
alkoxo and amido groups.
As previously mentioned, the amido complexes are thermally
unstable in solution. Thermolysis of complexes 6 and 10 takes
place over several hours at room temperature or within 30 or
45 min at 40 or 60 °C, respectively. The conversion is very
clean at temperatures slightly above room temperature, affording
the η2-imine derivatives 13 and 14 (Figure 3), respectively,
presumably through a â-hydrogen elimination reaction followed
by reductive elimination of methane, which has been identified
by GC.
The decomposition of the two primary amide derivatives, 11
and 12, is less clean, affording a mixture of NiMe2(dippe), Ni-
(dippe)2, and the corresponding η2-imine complexes, identified
on the basis of their characteristic 31P spectra, very similar to
those of 13 and 14, consisting of AB spin systems with relatively
Heterocumulene Insertion Reactions into Ni-N and Ni-O
Bonds. Transition metal alkoxide or amide complexes are
known to react with CO2 to afford addition products where this
molecule is formally inserted into the M-O or M-N bond.29
Studies on the carboxylation of Mo, W, Mn, and Rh alkoxides
show this reaction not to require prior coordination of CO2 to
the metal center, but it is a concerted process probably involving
a four-center transition state where the oxygen atom of the
alkoxide partially donates one of its lone electron pairs to the
weakly electrophilic C atom of CO2, simultaneously with the
formation of the M-OC(O) bond.8 Therefore, the feasibility
of this reaction provides an indication of the nucleophilicity of
2
large values of the JPP constant (>65 Hz).
Complexes 13 and 14 have been obtained as a crystalline
dark orange solid (13) and an orange oil (14), very soluble in
hydrocarbon solvents. Their 1H and 13C{1H} NMR spectra are
consistent with the proposed η2-binding mode of the imine
ligand and have been fully assigned with the aid of two-
dimensional COSY, NOESY, and HMQC experiments. For
example, the imine methyne carbon 13C signal occurs at δ 71.7
for 13 and 74.0 ppm for 14, in both cases split as a doublet by
the coupling to one of the phosphorus nuclei. The side-on
(26) Kraus, G. A.; Neuenschwander, K. J. Org. Chem. 1981, 46, 4791.
(27) Weng, Z.; Teo, S.; Koh, L. L.; Hor, T. S. A. Angew. Chem., Int.
Ed. 2005, 44, 7560.
(28) (a) Gabor, B.; Kru¨ger, C.; Marczinke, B.; Mynott, R.; Wilke, G.
Angew. Chem., Int. Ed. 1991, 30, 1666. (b) Karsch, H. H.; Leithe, A. W.;
Reisky, M.; Witt, E. Organometallics 1999, 18, 90.
(29) (a) Dell’Amico, D. B.; Calderazzo, F.; Labella, L.; Marchetti, F.;
Pampaloni, G. Chem. ReV. 2003, 103, 3857. (b) Yin, X.; Moss, J. R. Coord.
Chem. ReV. 1999, 181, 27.
(23) Mathis, M.; Harsha, T. W.; Bailey, R. D.; Schimek, G. L.;
Perrington, W. T. Chem. Mater. 1998, 10, 3568.
(24) (a) Braun, T.; Foxon, S. P.; Perutz, R. N.; Walton, P. H. Angew.
Chem., Int. Ed. 1999, 38, 3326. (b) Ca´mpora, J.; Lo´pez, J. A.; Maya, C.
M.; Palma, P.; Carmona, E.; Ruiz, C. Organometallics 2000, 19, 2707.
(25) Albe´niz, A. C.; Calle, V.; Espinet, P.; Go´mez, S. Inorg. Chem. 2001,
40, 4211.

3844 Organometallics, Vol. 26, No. 15, 2007
Ca´mpora et al
displays a signal corresponding to the carboxylic carbon, whose
position at δ 161.2 ppm can be considered typical of the
carbamato ligand.30
Both the alkoxo and amido complexes react cleanly and
selectively with phenyl isocyanate, yielding closely related
addition products, 16 and 17. Judging from the color change,
similar to that observed in its carboxylation, the reaction of 6
with this heterocumulene is essentially instantaneous even at
-80 °C. The reaction of 5 with PhNCO involves a more subtle
color change, which is difficult to appreciate, but 31P NMR
monitoring shows it requires at least 15 min of stirring at room
temperature to be complete. The elucidation of the structures
of these two compounds poses the problem of assigning the
precise coordination mode of the inserted functionality, which
in principle may happen either through the N(Ph) or the O
atoms. Both 16 and 17 display very similar spectroscopic
properties, suggesting they share the same coordination mode.
This can be noticed for example in the similarity of the 31P-
{1H} spectra (two singlets at ca. δ 62 and 77 ppm) and the
close chemical shifts of the 13C resonance of the carbon atom
of the inserted functionality (ca. δ 160 ppm). Unfortunately,
the latter parameter appears to be quite insensitive to the
structure of the XC(dY)Z fragment, as it is also almost
undistinguishable from those of carbamate 15. The IR absorption
bands of 16 and 17, 1634 and 1659 cm-1, respectively, are also
similar to those of 15. However, a positive structural assignment
has been possible on the basis of the 2D NOESY spectra of the
two compounds, both of them displaying NOE cross-peaks
linking the signal corresponding to the ortho protons of the N-Ph
group and one of the methyl groups of the diphosphine,
revealing the spatial proximity of these two groups. Thus, on
the basis of this clue, we favor the structures shown in Scheme
4 over the corresponding O-bound tautomers.
Figure 4. ORTEP view of 13. Selected bond lengths (Å) and angles
(deg) (one of two independent molecules in the asymmetric unit):
Ni(1)-N(1), 1.9038(19); Ni(1)-C(15), 1.942(2); Ni(1)-P(1),
2.1561(5); Ni(1)-P(2), 2.1412(6); N(1)-C(15), 1.352(3); N(1)-
Ni(1)-C(15), 41.13(10); N(1)-Ni(1)-P(1), 112.41(7); C(15)-Ni-
(1)-P(2), 114.85(8); P(2)-Ni(1)-P(1), 91.92(2).
Scheme 4
Incidentally, it must be mentioned that although spectroscopi-
cally pure samples of compound 17 have been obtained by
simply dissolving in C6D6 the residue left after evaporation of
the reaction of 6 with PhNCO, attempts to crystallize this
compound led to the isolation of analytically pure samples of
17′, a 1:1 adduct with the urea derivative N-phenylpyrrolydine-
1-carboxamide, presumably arising from the reaction of 17 with
1
small amounts of adventitious water. The NOESY H NMR
spectrum of this adducts displays EXSY cross-peaks linking
the free and coordinated ureas, indicating that these undergo a
slow exchange in solution.
the alkoxide or amide ligands.1a,b,8b,c Related heterocumulene
molecules such as carbon disulfide, isocyanates, or isothiocy-
anates react similarly to CO2, giving rise to a variety of addition
products.1d,6a We considered it worthwhile to examine the
reactivity of tert-butoxide 5 and amide 6 with these heterocu-
mulenes, in order have an indication of their relative nucleo-
philicities.
As shown in Scheme 4, complex 6 reacts cleanly with CO2
to give a single product, 15. The reaction is complete after dry
CO2 is bubbled for a few minutes into a solution of the amide,
as indicated by the perceptible color lightening. Although the
tert-butoxide 5 does also react under the same conditions, a
complex mixture of products is produced, whose characterization
was not attempted.
The spectral data of compound 15 support its formulation as
a carbamate derivative. The presence of this functionality is
evinced by a strong IR absorption at 1681 cm-1, while its 31P-
{1H} displays two resonances at δ 64.8 and 77.7 ppm, which
resemble those of the alkoxide complexes 7-9, as expected for
a product displaying both Ni-Me and Ni-O bonds. The
permanence of the methyl and pyrrolidine fragments is con-
firmed by the 1H and the 13C{1H} spectra. The latter also
Phenylisothiocyanate reacts selectively with 5 and 6, but at
a remarkably different rate. While the reaction with 5 takes
several hours to complete, it is still very fast in the case of 6,
even at -80 °C. In the 31P{1H} spectra of the corresponding
complexes 18 and 19, one of the two signals appears at ca. 80
ppm, appreciably displaced to lower field than it is commonly
observed in the remaining insertion products. This peculiarity
may be attributed to the presence of Ni-S instead of Ni-O or
Ni-N bonds, a proposal that has been confirmed by the
determination of the crystal structure 19. The methyl group and
the S-C-NC4H8 part of the ligand were found distributed in
two adjacent positions of the square-planar coordination, with
occupancy factors of 0.6 and 0.4, respectively. In Figure 5 only
one of the two disordered images is reported. A list of the most
important bond distances and angles for the two disordered
images is collected in the caption. The S-bound coordination
mode is not unexpected, given the higher affinity of late
(30) Blacque, O.; Brunner, H.; Kubicki, M. M.; Leblanc, J. C.; Meier,
W.; Moise, C.; Sardorge, A.; Wachter, J.; Zabel, M. J. Organomet. Chem.
2001, 47, 634.

Monomeric Alkoxo and Amido Methylnickel(II) Complexes
Organometallics, Vol. 26, No. 15, 2007 3845
Conclusions
Mononuclear alkoxo and amido methylnickel(II) derivatives
can be prepared by displacement of fluoride from the precursor
complex Ni(Me)(F)(dippe) (1c) with the corresponding lithium
alkoxides or amides. The alkoxides Ni(OR)(F)(dippe) (R ) Me,
CH2Ph, CH(Me)Ph) show higher stability than the previously
reported tert-butoxide, but amido complexes are thermally
unstable and slowly decompose in solution at room temperature.
Secondary amides Ni(Me)(NR2)(dippe) (NR2 ) pyrrolidino,
N(CH2Ph)2) undergo a â-hydrogen elimination reaction, which
ultimately leads to the corresponding η2-imine complexes.
However, the decomposition of primary amides Ni(Me)(NHR)-
(dippe) is less selective, affording a mixture of products. The
alkoxide and amide complexes 5 and 6 readily react with CO2,
PhNCO, and PhNCS, giving rise to products arising from the
formal insertion of the heterocumulenes into the Ni-O or the
Ni-N bond. These reactions proceed faster with 6 than with 5,
illustrating the higher nucleophilicity of amide complexes. While
the structure of the addition products indicates that the ther-
modynamic preference for CdX addition decreases in the order
CdS > CdN > CdO, PhNCO reacts faster with 5 than PhNCS,
suggesting that a direct nucleophilic addition mechanism
operates in these reactions.
Figure 5. ORTEP view of 19 (only one of the two possible
orientations of the organic moiety is represented for clarity).
Selected bond lengths (Å) and angles (deg): Ni(1)-S(1A), 2.1224-
(9); Ni(1)-C(1A), 1.9998(11); Ni(1)-P(1), 2.1757(12); Ni(1)-
P(2), 2.1471(11); N(1)-C(2A), 1.280(7); N(2A-C(2A), 1.347(8);
S(1A)-Ni(1)-C(1A), 92.5(2); S(1A)-Ni(1)-P(1), 93.44(6); C(1A)-
Ni(1)-P(2), 84.8(2); P(2)-Ni(1)-P(1), 89.26(4).
Experimental Section
transition metals for sulfur than for the harder oxygen or nitrogen
atoms. The S-bonded coordination mode can also be expected
to be more stable because it preserves the stronger π-CdN rather
than the weaker π-CdS bond.
General Considerations. All preparations were carried out under
oxygen-free nitrogen by conventional Schlenk techniques. Solvents
were rigorously dried and degassed before use. Carbon dioxide was
dried over P2O5 in a Fisher-Porter reactor charged at 3 bar for at
least 1 week. Infrared spectra were recorded on a Bruker Vector
22 spectrometer, and NMR spectra on Bruker DRX 300 and 400
MHz spectrometers. The 1H and 13C{1H} resonances of the solvent
were used as the internal standard, but the chemical shifts are
reported with respect to TMS. 31P resonances are referenced to
external 85% H3PO4, and 19F to external CFCl3. GC analyses were
performed by using a Hewlett-Packard Model HP 6890 chromato-
graph and GC-MS on a Thermoquest Automasss Multi gas
chromatograph-mass spectrometer. Microanalyses were performed
by the Microanalytical Service of the Instituto de Investigaciones
Qu´ımicas (Sevilla, Spain). Compounds 5, 10, 11, 14, and 15 could
not be isolated in crystalline form due to their exceedingly high
solubility in organic solvents. This feature, combined with their
thermal and hydrolytic sensitivity, prevented the gathering of
accurate elemental analysis data for these compounds. Although
the amido complex 12 could be crystallized, repeated attempts to
accomplish elemental analysis failed, presumably due to its thermal
lability.
Synthesis of Ni(dippe)(CH3)2.10 A 7.1 mL portion of a 1.4 M
solution (10 mmol) of LiMe was added to a suspension of 1.96 g
of Ni(dippe)(Cl)2 (5 mmol) in THF cooled at -78 °C. After stirring
15 min at room temperature solvent was removed under vacuum
and the yellow solid was extracted with diethyl ether. Crystallization
at -20 °C gave the product as yellow crystals in 85% yield.
Synthesis of Ni(dippe)(CH3)(Cl) (1a). A 600 mg sample of Ni-
(dippe)(CH3)2 (1.7 mmol) was dissolved in 5 mL of THF and added
to a suspension of 167 mg of (CH3)3N‚HCl (1.7 mmol) in 10 mL
of THF. After stirring 4 h at room temperature solvent was removed
under vacuum and the orange solid was extracted with 10 mL of
THF. Concentration to dryness gave the product as an orange solid
As anticipated, the NOESY spectra of the phenylisothiocy-
anate insertion products show no cross-peaks between the N-Ph
signals and those of the Ni(dippe) fragment, adding credence
to the opposite coordination mode assigned to 16 and 17, which
do show such spatial relationship. It is also interesting to
compare the lower frequency of the IR band associated with
the functionality arising from phenylisothiocyanate insertion (18,
1539; 19, 1548 cm-1) with the corresponding ones of 15 and
16, all of them above 1600 cm-1. This observation also points
to the existence of a CdO in the latter compounds and a Cd
NPh in the former, since the CdX bond stretch is probably
one of the main contributors to these bands.
As a final comment, the qualitative differences observed in
the reaction rates of 5 and 6 toward PhNCO and PhNCS clearly
stress the higher nucleophilicity of the amide as compared to
the alkoxide complex. The structure of the insertion products
confirms that the preference for CdX insertion decreases in
the order CdS > CdNPh > CdO, which doubtless has a
thermodynamic origin. The same trend has been previously
observed in the insertion of heterocumulenes into M-X
complexes of Pd,31 Rh,32 and Ir.1d In spite of the favorable
thermodynamics of CdS insertion, PhNCO reacts faster than
PhCNS with 5. This result contrasts with the trend observed in
the reaction of heterocumulenes with Ni-C bonds,33 where a
migratory insertion mechanism has been proposed to operate,
but fits well with a direct nucleophilic attack of the alkoxide
on the central carbon of the heterocumulene, as PhNCO is
expected to behave as a stronger electrophile than PhNCS.34
(31) Ruiz, J.; Mart´ınez, M. T.; Florenciano, F.; Rodr´ıguez, V.; Lo´pez,
G. Inorg. Chem. 2003, 42, 3650.
(32) Piraino, P.; Bruno, G.; Tresoldi, G.; Faraone, G.; Bombieri, G. J.
Chem. Soc., Dalton Trans. 1983, 2391.
(33) Ca´mpora, J.; Gutie´rrez, E.; Monge, A.; Palma, P.; Poveda, M. L.;
Ruiz, C.; Carmona, E. Organometallics 1994, 13, 1728.
(34) Duus, F. In ComprehensiVe Organic Chemistry; Jones, D. N., Ed.;
Pergamon Press: Oxford, 1979; Vol. 3.
1
in 71% yield. H NMR (CD2Cl2, 400 MHz): δ -0.10 (pt, 3H,
J*HP ≈ 5.7 Hz, Ni-CH3), 1.18 (dd, 6H, 3JHP ) 12.7 Hz, 3JHH ) 7.2
3
3
Hz, PCHMeMe), 1.24 (dd, 6H, JHP ) 13.8 Hz, JHH ) 7.2 Hz,
3
3
PCHMeMe)), 1.31 (dd, 6H, JHP ) 15.5 Hz, JHH ) 6.7 Hz,
3
3
PCHMeMe), 1.36 (dd, 6H, JHP ) 15.2 Hz, JHH ) 7.0 Hz,
PCHMeMe), 1.70 (m, 2H, CH2), 2.23 (m, 4H, CH). 13C{1H} NMR

3846 Organometallics, Vol. 26, No. 15, 2007
Ca´mpora et al
1
(CD2Cl2, 75 MHz): δ -0.29 (dd, 2JCP ) 73, 37 Hz, Ni-CH3), 17.7
C, 51.02; H, 10.28. Found: C, 50.85; H, 10.22. H NMR (C6D6,
400 MHz): δ -0.49 (dd, 1H, 3JHP ) 10.0, 3.0 Hz, OH), 0.18 (dd,
3H, 3JHP ) 5.9, 4.4 Hz, Ni-CH3), 0.79 (m, 2H, CH2), 0.83 (dd, 6H,
(dd, 1JCP ) 19 Hz, 2JCP ) 11 Hz, CH2), 18.7 (s, PCHMeMe), 19.8
2
(d, JCP ) 4, PCHMeMe), 20.3 (s, PCHMeMe), 24.4 (pt, J*CP
≈
24 Hz, CH2), 24.7 (d, 1JCP ) 17 Hz, PCHMe2), 26.3 (d, 1JCP ) 29
3JHP ) 9.9 Hz, JHH ) 7.0 Hz, PCHMeMe), 0.97 (m, 2H, CH2),
1.03 (dd, 6H, JHP ) 12.5 Hz, JHH ) 7.1 Hz, PCHMeMe), 1.10
(dd, 6H, JHP ) 15.2 Hz, JHH ) 7.2 Hz, PCHMeMe), 1.51 (dd,
6H, JHP ) 15.1 Hz, JHH ) 7.2 Hz, PCHMeMe), 1.68 (m, 2H,
PCHMe2), 2.13 (m, 2H, PCHMe2). 13C{1H} NMR (C6D6, 75
MHz): δ -0.6 (dd, 2JCP ) 82 and 32 Hz, Ni-CH3), 15.7 (pt, J*CP
≈ 19 Hz, CH2), 16.9 (pt, J*CP ≈ 16 Hz, CH2), 18.0 (s, PCHMeMe),
18.3 (s, PCHMeMe), 19.3 (s, PCHMeMe), 19.4 (s, PCHMeMe),
23.7 (m, PCHMe2), 24.7 (d, 1JCP ) 25 Hz, PCHMe2). 31P{1H} NMR
3
Hz, PCHMe2). 31P{1H} NMR (CD2Cl2, 162 MHz): δ 69.4 (d, 2JPP
3
3
2
3
3
) 10 Hz), 81.1 (d, JPP ) 10 Hz).
3
3
Synthesis of Ni(dippe)(CH3)(OTf) (1b). A 7.7 mL amount of
a 0.13 M solution of trifluoromethanesulfonic (triflic) acid (1
mmol) was added to 350 mg of Ni(dippe)(Me)2 (1 mmol) in 10
mL of THF cooled at -78 °C. The reaction mixture was allowed
to reach room temperature. Monitoring by 31P{1H} NMR revealed
quantitative conversion of the dialkyl complex to the new product
1b. 31P{1H} NMR (THF, 121 MHz): δ 65.6, 77.8. Working up
the reaction mixture leads to the isolation of the dinuclear hydroxide
[Ni(dippe)(µ-OH)]2‚2(OTf) (2).11 Selected spectroscopic data for
2
(C6D6, 162 MHz): δ 68.6 (d, JPP ) 9 Hz), 77.3 (d).
Synthesis of Ni(dippe)(CH3)(OC(CH3)3) (5). A 0.26 mL amount
of a 1.7 M solution of LiBun (0.45 mmol) was added to 47 µL of
tert-butanol (0.49 mmol) dissolved in 5 mL of THF at -78 °C.
The reaction mixture was stirred and allowed to reach room
temperature, then added to a cooled (-78 °C) solution of 160 mg
of Ni(dippe)(Me)(F) (0.45 mmol) in 5 mL of THF. The solvent
was removed under reduced pressure, and the residue was extracted
with 0.8 mL of C6D6 and centrifuged to afford a dark red solution
of the pure product. Previous attempts to crystallize this compound
from cold hexane or pentane failed due to its high solubility in
these solvents and low thermal stability. 1H NMR (C6D6, 300
MHz): δ 0.22 (pt, 3H, J*HP ≈ 5.7 Hz, Ni-CH3), 0.68 (m, 2H, CH2),
3
2: 1H NMR (CD2Cl2, 300 MHz) δ -1.51 (d, 1H, JHP ) 1.9 Hz,
OH), 1.25 (dd, 12H, 3JHP ) 13.9 Hz, 3JHH ) 7.0 Hz, PCHMeMe),
1.56 (d, 4H, 2JHP ) 11.3 Hz, CH2), 1.67 (dd, 12H, 3JHP ) 17.9 Hz,
3JHH ) 7.0 Hz, PCHMeMe), 2.38 (m, 4H, PCHMe2). 31P{1H} NMR
(CD2Cl2, 162 MHz): δ 88.0.
Synthesis of Ni(dippe)(CH3)(F) (1c). To a cooled (-78 °C)
solution of Ni(dippe)(Me)2 (702 mg, 2 mmol) in 10 mL of THF
was added 2.7 mL of a 0.25 M solution of Et3N‚3HF. The reaction
mixture was allowed to reach room temperature. The solvent was
removed under vacuum and the residue was extracted with 10 mL
of THF to afford an orange solution, which was concentrated to
yield the product as orange crystals. Yield ) 78%. Anal. Calcd for
3
3
0.86 (dd, 6H, JHP ) 12.7 Hz, JHH ) 7.0 Hz, PCHMeMe), 1.01
(dd, 6H, JHP ) 11.9 Hz, JHH ) 7.1 Hz, PCHMeMe), 1.14 (dd,
3
3
1
C15H35FNiP2: C, 50.74; H, 9.94. Found: C, 50.52; H, 9.99. H
3
3
6H, JHP ) 15.1 Hz, JHH ) 7.2 Hz, PCHMeMe), 1.49 (dd, 6H,
NMR (C6D6, 400 MHz): δ 0.47 (m, 3H, Ni-CH3), 0.72 (m, 2H,
3JHP ) 16.9 Hz, JHH ) 7.1 Hz, PCHMeMe, 1.69 (s, 9H, CMe3),
3
3
3
CH2), 0.82 (dd, 6H, JHP ) 13.3 Hz, JHH ) 7.0 Hz, PCHMeMe),
2.05 (m, 2H, PCHMe2). 13C{1H} NMR (C6D6, 75 MHz): δ -8.3
(dd, 2JCP ) 80, 36 Hz, Ni-CH3), 15.6 (dd, 1JCP ) 15 Hz, 2JCP ) 12
Hz, CH2), 18.1 (s, PCHMeMe), 18.2 (s, PCHMeMe), 19.5 (d, 2JCP
3
3
0.93 (m, 2H, CH2), 1.02 (dd, 6H, JHP ) 12.8 Hz, JHH ) 7.1 Hz,
PCHMeMe), 1.10 (dd, 6H, JHP ) 15.5 Hz, JHH ) 7.2 Hz,
3
3
3
3
PCHMeMe), 1.41 (dd, 6H, JHP ) 15.0 Hz, JHH ) 7.1 Hz,
PCHMeMe), 1.63 (m, 2H, PCHMe2), 1.92 (m, 2H, PCHMe2). 13C-
2
) 6 Hz, PCHMeMe), 19.6 (d, JCP ) 3 Hz, PCHMeMe), 23.5 (d,
1JCP ) 14 Hz, PCHMe2), 24.7 (d, JCP ) 26 Hz, PCHMe2), 35.9
1
{1H} NMR (C6D6, 100 MHz): δ 2.8 (dd, JCP ) 83 and 37 Hz,
2
(s, CMe3), 70.1 (d, 3JCP ) 4 Hz, CMe3). 31P{1H} NMR (C6D6, 121
1
2
Ni-CH3), 16.6 (dd, JCP ) 19 Hz, JCP ) 11 Hz, CH2), 18.5 (s,
2
MHz): δ 60.5 (d, JPP ) 11 Hz), 70.4 (d).
2
PCHMeMe), 18.9 (s, PCHMeMe), 19.6 (d, JCP ) 5 Hz, PCH-
MeMe), 19.9 (d, 2JCP ) 2 Hz, PCHMeMe), 24.0 (d, 1JCP ) 13 Hz,
Synthesis of [Ni(dippe)(CH3)(NCH2(CH2)2CH2)] (6). A 0.22
mL amount of a 1.6 M solution of LiBun (0.35 mmol) in hexane
was added at -78 °C to 32 µL of pyrrolidine (0.35 mmol) dissolved
in 3 mL of THF. The reaction mixture was stirred and allowed to
reach room temperature, then added to a cooled (-78 °C) solution
of 123 mg of Ni(dippe)(Me)(F) (0.35 mmol) in 3 mL of THF. 31P-
1
PCHMe2), 24.5 (pt, J*CP ≈ 24 Hz, CH2), 25.5 (d, JCP ) 28 Hz,
PCHMe2). 31P{1H} NMR (C6D6, 162 MHz): δ 64.6 (d, 2JPF ) 50
Hz), 78.4 (d, JPF ) 117 Hz). 19F{1H} NMR (C6D6, 376 MHz):
2
2
-224.0 (dd, JFP ) 117 and 50 Hz).
Reaction of Ni(dippe)(CH3)(OTf) (1b) with Lithium Hydrox-
ide. A 1.26 mL sample of a 0.35 M solution of triflic acid (0.44
mmol) was added to 5 mL of a THF solution containing 155 mg
of Ni(dippe)(Me)2 (0.44 mmol) at -78 °C. After reaching room
temperature, the reaction mixture was cooled again and 0.44 mmol
of LiOH was added. Solvent was removed under vacuum and the
residue was extracted with 0.8 mL of CD2Cl2. 1H and 31P{1H} NMR
show resonances of the hydroxide 2, together with those of the
complex 3. Evaporation of the sample and extraction of the residue
with C6D6 allowed removal of most of 2 and the recording of NMR
{1H} NMR (THF, 121 MHz): δ 55.7 (d, JPP ) 8 Hz), 72.3 (d).
The low thermal stability of this compound prevented its isolation.
2
Synthesis of Ni(dippe)(CH3)(OR) (R ) CH3, 7; CH2Ph, 8;
CH(CH3)Ph, 9). These compounds were prepared by reaction of
Ni(dippe)(CH3)(F) 1c with the lithium alkoxides as exemplified
by the synthesis of compound 7: 0.31 mL of a 1.6 M solution of
LiBun (0.5 mmol) was added to 20 µL of methanol (0.5 mmol)
dissolved in 5 mL of THF at -78 °C. The reaction mixture was
stirred and allowed to reach room temperature, then added to a
cooled (-78 °C) solution of 176 mg of Ni(dippe)(Me)(F) (0.5
mmol) in 3 mL of THF. After reaching room temperature, solvent
was removed under reduced pressure and the solid was extracted
with 5 mL of Et2O. The product was obtained after crystallization
at -20 °C in a 45% yield. Anal. Calcd for C16H38ONiP2: C, 52.35;
H, 10.43. Found: C, 52.40; H, 10.45. 1H NMR (C6D6, 300 MHz):
δ 0.23 (bs, 3H, Ni-CH3), 0.84 (m, 6H, PCHMeMe), 1.07 (m, 12H,
PCHMeMe), 1.45 (m, 6H, PCHMeMe), 1.70 (m, 2H, PCHMe2),
2.05 (m, 2H, PCHMe2), 4.08 (s, 3H, OCH3). 13C{1H} NMR (C6D6,
1
spectra of 3. H NMR (C6D6, 300 MHz): δ -2.28 (s, 1H, OH),
0.39 (pt, 6H, J*HP ≈ 4.5 Hz, Ni-CH3), 0.94 (dd, 12H, 3JHP ) 13.7
Hz, 3JHH ) 7.0 Hz, PCHMeMe), 1.13 (m, 24H, PCHMeMe), 1.34
3
3
(dd, JHP ) 15.0 Hz, JHH ) 7.2 Hz, PCHMeMe), 1.73 (m, 4H,
PCHMe2), 1.99 (m, 4H, PCHMe2). 31P{1H} NMR (C6D6, 162
MHz): δ 62.7, 75.6.
Synthesis of Ni(dippe)(CH3)(OH) (4). Compound 1c (355 mg,
1 mmol) dissolved in 10 mL of THF was added to a solution of
LiOH in THF at -78 °C. The latter was previously prepared by
adding 0.6 mL of a 1.6 M solution (1 mmol) of nBuLi in hexane to
a cooled solution of 18 µL of water (1 mmol) in 10 mL of THF.
After stirring to room temperature solvent was removed under
reduced pressure, and the residue was extracted with 15 mL of
diethyl ether. The product crystallized from this solution after
cooling at -20 °C. Yield ) 70%. Anal. Calcd for C15H36ONiP2:
2
75 MHz): δ -1.8 (dd, JCP ) 73 and 33 Hz, Ni-CH3), 16.2 (dd,
1JCP ) 16 Hz, JCP ) 12 Hz, CH2), 18.1 (s, PCHMeMe), 18.2 (s,
2
PCHMeMe), 19.2 (d, 2JCP ) 5 Hz, PCHMeMe), 19.5 (d, 2JCP ) 3
1
Hz, PCHMeMe), 23.4 (d, JCP ) 14 Hz, PCHMeMe), 24.1 (dd,
1JCP ) 25 Hz, JCP ) 22 Hz, PCHMe2), 24.8 (d, JCP ) 25 Hz,
2
1

Monomeric Alkoxo and Amido Methylnickel(II) Complexes
Organometallics, Vol. 26, No. 15, 2007 3847
PCHMe2), 52.9 (d, 3JCP ) 4 Hz, OCH3). 31P{1H} NMR (C6D6, 121
(d, 2H, 3JHH ) 7.5 Hz, CarHo). 13C{1H} NMR (C6D6, 75 MHz): δ
2
2
MHz): δ 63.6 (d, JPP ) 8 Hz), 75.5 (d).
-2.4 (dd, JCP ) 68 and 34 Hz, Ni-CH3), 18.1 (s, PCHMeMe),
2
18.2 (s, PCHMeMe), 19.0 (d, JCP ) 6 Hz, PCHMeMe), 19.6 (d,
Compound 8: 62% yield after cristallization from Et2O. Anal.
Calcd for C22H42ONiP2: C, 59.62; H, 9.55. Found: C, 59.16; H,
9.53. 1H NMR (C6D6, 300 MHz): δ 0.18 (pt, 3H, J*HP ≈ 5.0 Hz,
1
2
2JCP ) 4 Hz, PCHMeMe), 23.0 (dd, JCP ) 24 Hz, JCP ) 19 Hz,
1
1
CH2), 23.9 (d, JCP ) 13 Hz, PCHMe2), 24.9 (d, JCP ) 24 Hz,
PCHMe2), 51.7 (d, 3JCP ) 5 Hz, NHCH2Ph), 124.8 (s, CarH), 151.5
(s, Car). 31P{1H} NMR (C6D6, 121 MHz): δ 69.7 (d, 2JPP ) 5 Hz),
78.5 (d).
Ni-CH3), 0.77 (m, 2H, CH2), 0.84 (dd, 6H, 3JHP ) 12.8 Hz, 3JHH
)
7.0 Hz, PCHMeMe), 0.98 (dd, 6H, 3JHP ) 12.2 Hz, 3JHH ) 7.1 Hz,
3
3
PCHMeMe), 1.10 (dd, 6H, JHP ) 15.3 Hz, JHH ) 7.2 Hz,
3
3
Synthesis of Ni(dippe)(CH3)(NHCH(CH3)Ph) (12). A 0.21 mL
portion of a 1.7 M solution of LiBun (0.35 mmol) was added to 45
µL of 1-phenylethylamine (0.35 mmol) dissolved in 3 mL of THF
at -78 °C. The mixture was allowed to reach room temperature
and added to a cooled (-78 °C) solution of 124 mg of Ni(dippe)-
(Me)(F) (0.35 mmol) in 3 mL of THF. After reaching room
temperature, solvent was removed under vacuum and the dark red
residue was extracted with 3 mL of pentane. The product was
obtained after crystallization at -20 °C. 1H NMR (C6D6, 300
MHz): δ 0.27 (dd, 3H, 3JHP ) 7.1 and 4.5 Hz, Ni-CH3), 0.84 (m,
12H, PCHMeMe), 1.12 (m, 12H, PCHMeMe), 1.72 (m, 2H,
PCHMeMe), 1.42 (dd, 6H, JHP ) 15.0 Hz, JHH ) 7.1 Hz,
PCHMeMe), 1.68 (m, 2H, PCHMe2), 2.04 (m, 2H, PCHMe2), 5.20
(d, 2H, 4JHP ) 3.2 Hz, OCH2Ph), 7.18 (m, 1H, CarHp), 7.39 (t, 2H,
3JHH ) 7.5 Hz, CarHm), 7.86 (d, 2H, JHH ) 7.5 Hz, CarHo). 13C-
3
{1H} NMR (C6D6, 75 MHz): δ -2.2 (dd, JCP ) 72 and 34 Hz,
2
1
2
Ni-CH3), 16.1 (dd, JCP ) 17 Hz, JCP ) 12 Hz, CH2), 18.1 (s,
2
PCHMeMe), 18.2 (s, PCHMeMe), 19.3 (d, JCP ) 6 Hz, PCH-
MeMe), 19.5 (d, 2JCP ) 3 Hz, PCHMeMe), 23.5 (d, 1JCP ) 14 Hz,
1
2
PCHMe2), 23.9 (dd, JCP ) 25 Hz, JCP ) 22 Hz, PCHMe2), 24.9
(d, 1JCP ) 26 Hz, PCHMe2), 66.7 (d, 3JCP ) 5 Hz, OCH2Ph), 124.7
(s, CarHp), 126.7 (s, CarHo), 151.1 (s, Car). 31P{1H} NMR (C6D6,
3
2
PCHMe2), 1.77 (d, 3H, JHH ) 6.4 Hz, NHCH(CH3)Ph), 1.90 (m,
121 MHz): δ 64.1 (d, JPP ) 8 Hz), 75.5 (d).
2H, PCHMe2), 4.80 (m, 1H, NHCH(CH3)Ph), 7.15 (m, 1H, CarHp),
Compound 9: 58% yield after crystallization from pentane at
-80 °C. Anal. Calcd for C23H44ONiP2: C, 60.42; H, 9.70. Found:
3
3
7.37 (t, 2H, JHH ) 7.6 Hz, CarHm), 7.90 (d, 2H, JHH ) 7.2 Hz,
CarHo). 13C{1H} NMR (C6D6, 75 MHz): δ -3.2 (dd, JCP ) 68
and 34 Hz, Ni-CH3), 17.9 (s, PCHMeMe), 18.0 (s, PCHMeMe),
2
1
C, 59.82; H, 9.88. H NMR (C6D6, 300 MHz): δ 0.06 (pt, 3H,
J*HP ≈ 5.1 Hz, Ni-CH3), 0.79 (m, 6H, PCHMeMe), 1.02 (m, 6H,
2
2
18.3 (d, JCP ) 4 Hz, PCHMeMe), 18.9 (d, JCP ) 6 Hz,
PCHMeMe), 19.2 (d, 2JCP ) 6 Hz, PCHMeMe), 19.6 (d, 2JCP ) 4
Hz, PCHMeMe), 19.7 (d, 2JCP ) 4 Hz, PCHMeMe), 22.9 (dd, 1JCP
3
3
PCHMeMe), 1.40 (dd, 6H, JHP ) 15.0 Hz, JHH ) 7.1 Hz,
3
3
PCHMeMe), 1.52 (dd, 6H, JHP ) 14.5 Hz, JHH ) 7.1 Hz,
PCHMeMe), 1.63 (m, 2H, PCHMe2), 1.76 (d, 3H, 3JHH ) 6.2 Hz,
OCH(CH3)Ph), 2.08 (m, 2H, PCHMe2), 5.27 (bs, 1H, OCH(CH3)-
Ph), 7.19 (m, 1H, CarHp), 7.40 (t, 2H, 3JHH ) 7.4 Hz, CarHm), 7.87
(d, 2H, 3JHH ) 7.1 Hz, CarHo). 13C{1H} NMR (C6D6, 75 MHz): δ
2
1
) 24 Hz, JCP ) 18 Hz, CH2), 23.7 (d, JCP ) 13 Hz, PCHMe2),
24.4 (d, 1JCP ) 13 Hz, PCHMe2), 25.1 (d, 1JCP ) 24 Hz, PCHMe2),
4
3
31.1 (d, JCP ) 3 Hz, NHCH(CH3)Ph), 54.1 (d, JCP ) 5 Hz,
NHCH(CH3)Ph), 124.5 (s, CarH), 126.0 (s, CarH), 126.8 (s, CarH),
2
-3.3 (dd, JCP ) 72 and 34 Hz, Ni-CH3), 18.0 (s, PCHMeMe),
156.0 (s, Car). 31P{1H} NMR (C6D6121 MHz): δ 68.8 (d, JPP
)
2
2
18.5 (s, PCHMeMe), 19.1 (d, JCP ) 4 Hz, PCHMeMe), 19.6 (s,
5 Hz), 78.0 (d).
1
1
PCHMeMe), 23.2 (d, JCP ) 13 Hz, PCHMeMe), 23.9 (d, JCP
)
15 Hz, PCHMe2), 24.9 (dd, 1JCP ) 26 Hz, 2JCP ) 8 Hz, PCHMe2),
30.6 (s, OCH(CH3)Ph), 69.3 (d, 3JCP ) 5 Hz, OCH(CH3)Ph), 124.7
(s, CarHp), 126.5 (s, CarHo), 155.4 (s, Car). 31P{1H} NMR (C6D6,
Synthesis of [Ni(dippe)(η2-NdC(H)CH2CH2CH2)] (13). A
solution of lithium pyrrolidinide (38 mg, 0.5 mmol) in 3 mL of
THF was added to a cooled solution (-78 °C) of Ni(dippe)(Me)-
(F) (178 mg, 0.5 mmol) in 3 mL of THF. The cooling bath was
removed and the solution heated at 40 °C for 30 min. The solvent
was then removed under vacuum and the residue extracted with
hexane. Crystallization at -20 °C gave the product as a dark orange
solid. Yield ) 35%. Anal. Calcd for C18H39NNiP2: C, 55.41; H,
2
162 MHz): δ 63.2 (d, JPP ) 7 Hz), 75.2 (d).
Synthesis of Ni(dippe)(CH3)(N(CH2Ph)2) (10). A 0.15 mL
amount of a 1.6 M solution of LiBun (0.25 mmol) was added to
50 µL of dibenzylamine (0.25 mmol) dissolved in 3 mL of THF at
-78 °C. The purple mixture was allowed to reach room temperature
and then added to a cooled (-78 °C) solution of 90 mg of Ni-
(dippe)(Me)(F) (0.25 mmol) in 3 mL of THF. After reaching room
temperature, solvent was removed under vacuum and the dark red
1
10.08; N, 3.59. Found: C, 55.14; H, 10.63; N, 3.37. H NMR
(toluene-d8, -20 °C, 300 MHz): δ 0.87 (m, 9H, PCHMeMe), 1.00
3
3
(m, 12H, CH3), 1.34 (dd, 3H, JHP ) 15.0 Hz, JHH ) 6.9 Hz,
PCHMeMe), 1.72 (m, 4H, CH), 2.03 (m, 1H, CH2 imine), 2.31
(m, 1H, CH2 imine), 2.53 (m, 1H, CH2 imine), 3.67 (m, 1H, CH2
1
residue was extracted with 0.6 mL of C6D6. H NMR (C6D6, 300
3
MHz): δ 0.25 (bs, 3H, Ni-CH3), 0.87 (dd, 12H, JHP ) 12.0 Hz,
3JHH ) 6.9 Hz, PCHMeMe), 1.11 (dd, 6H, 3JHP ) 14.9 Hz, 3JHH
)
3
imine), 4.08 (m, 1H, CH2 imine), 4.41 (d, 1H, JHP ) 12.7 Hz,
7.2 Hz, PCHMeMe), 1.21 (dd, 6H, 3JHP ) 14.8 Hz, 3JHH ) 7.2 Hz,
PCHMeMe), 1.69 (m, 2H, PCHMe2), 1.85 (m, 2H, PCHMe2), 4.10
NdCH imine). 13C{1H} NMR (toluene-d8, -20 °C, 75 MHz): δ
17.9 (s, PCHMeMe), 18.3 (s, PCHMeMe), 18.8 (s, PCHMeMe),
19.2 (s, PCHMeMe), 19.6 (s, PCHMeMe), 19.9 (s, PCHMeMe),
20.1 (s, PCHMeMe), 20.4 (s, PCHMeMe), 20.6 (pt, J*CP ≈ 19 Hz,
3
(s, 4H, CH2Ph), 7.18 (m, 2H, CarHp), 7.33 (t, 4H, JHH ) 6.9 Hz,
CarHm), 7.88 (d, 4H, 3JHH ) 6.9 Hz, CarHo). 13C{1H} NMR (C6D6,
2
1
3
75 MHz): δ -2.2 (dd, JCP ) 68 and 29 Hz, Ni-CH3), 18.1 (s,
CH2), 21.4 (pt, J*CP ) 20 Hz, CH2), 24.0 (dd, JCP ) 11 Hz, JCP
) 3 Hz, PCHMe2), 24.4 (pt, J*CP ≈ 4 Hz, PCHMe2), 24.6 (d, 1JCP
PCHMeMe), 18.3 (s, PCHMeMe), 19.5 (s, PCHMeMe), 19.6 (s,
PCHMeMe), 22.0 (pt, J*CP ≈ 19 Hz, PCHMe2), 23.5 (d, 1JCP ) 14
Hz, PCHMe2), 24.2 (m, PCHMe2), 60.0 (s, CH2Ph), 125.2 (s, CarH),
126.7 (s, CarH), 129.7 (s, CarH), 146.6 (s, Car). 31P{1H} NMR (C6D6,
20 °C, 121 MHz): δ 49.7, 69.2.
3
) 5 Hz, PCHMe2), 24.8 (dd, JCP ) 6 Hz, obscured by peak at
3
24.4, PCHMe2), 30.4 (s, CH2 imine), 35.2 (d, JCP ) 3 Hz, CH2
imine), 61.3 (d, 3JCP ) 2 Hz, CH2 imine), 71.68 (d, 2JCP ) 19 Hz,
NdCH imine). 31P{1H} NMR (toluene-d8, -20 °C, 121 MHz): δ
2
2
57.7 (d, JPP ) 81 Hz), 68.8 (d, JPP ) 81 Hz).
Synthesis of Ni(dippe)(CH3)(NHCH2Ph) (11). This complex
is prepared following the method described above for complex 10,
using benzylamine instead of dibenzylamine. Like in the case of
10, the residue obtained after removing the solvent was extracted
with 0.6 mL of C6D6. 1H NMR (C6D6, 300 MHz): δ 0.32 (dd, 3H,
3JHP ) 6.9 and 4.5 Hz, Ni-CH3), 0.79-1.14 (m, 12H, PCHMeMe),
Synthesis of Ni(dippe)(η2-PhCH2NdCHPh) (14). Complex 10
was prepared in situ according to the method described above. After
removing the cooling bath, the reaction mixture was heated at 60
°C for 45 min. Evaporation of the solvent afforded a dark red
residue, which was extracted with 0.6 mL of C6D6. 1H NMR (C6D6,
300 MHz): δ 0.34 (dd, 3H, 3JHP ) 15.2 and 7.1 Hz, PCHMeMe),
3
3
1.27 (dd, 6H, JHP ) 14.4 Hz, JHH ) 7.2 Hz, PCHMeMe), 1.30
3
3
3
(dd, 6H, JHP ) 14.4 Hz, JHH ) 7.0 Hz, PCHMeMe), 1.79 (m,
4H, PCHMe2), 4.62 (dd, 2H, 3JHH ) 7.5 Hz, 4JHP ) 3.5 Hz, NHCH2-
Ph), 7.14 (m, 1H, CarHp), 7.32 (t, 2H, 3JHH ) 7.5 Hz, CarHm), 7.84
0.62 (pt, 3H, 3JHP ≈ JHH ≈ 8.2, PCHMeMe), 1.05-1.83 (m, 12H,
3
3
PCHMeMe), 1.14 (dd, 3H, JHP ) 14.2 Hz, JHH ) 7.0 Hz,
3
3
PCHMeMe), 1.27 (dd, 3H, JHP ) 14.3 Hz, JHH ) 6.9 Hz,

3848 Organometallics, Vol. 26, No. 15, 2007
Ca´mpora et al
PCHMeMe), 1.52 (m, 1H, PCHMe2), 1.60-1.86 (m, 3H, PCHMe2),
was removed under reduced pressure, and the resulting residue was
extracted with 0.6 mL of C6D6, thus affording an orange solution
of pure complex 17. Extraction of the same reaction crude with 5
mL of diethyl ether and crystallization at -20 °C led to the isolation
of the adduct 17‚PhNHC(O)NC4H8 (17′) in 50% yield. Compound
17: 1H NMR (C6D6, 300 MHz): δ 0.35 (s, 3H, Ni-CH3), 0.89-
1.21 (m, 24H, PCHMeMe), 1.66 (m, 2H, PCHMe2), 1.78 (m, 2H,
PCHMe2), 1.40 (s, 4H, NCH2CH2), 3.48 (s, 4H, NCH2CH2), 6.76
(t, 1H, 3JHH ) 7.7 Hz, CarHp), 7.23 (t, 2H, 3JHH ) 8.3 Hz, CarHm),
2
4.00 (d, 1H, JHH ) 14.5 Hz, PhCHHNdCHPh), 4.92 (dd, 1H,
4
2JHH ) 14.5 Hz, JHP ) 3.0 Hz, PhCHHNdCHPh), 4.98 (d, 1H,
3JHP ) 6.5 Hz, PhCH2NdCHPh), 6.94 (t, 1H, 3JHH ) 6.9 Hz, CarHp),
3
7.08 (t, 1H, JHH ) 7.5 Hz, CarHp), 7.14-7.27 (m, 4H, CarHm),
3
3
7.65 (d, 2H, JHH ) 7.5 Hz, CarHo), 7.76 (d, 2H, JHH ) 7.4 Hz,
CarHo). 13C{1H} NMR (C6D6, 75 MHz): δ 15.5 (d, 1JCP ) 21 Hz,
CH2), 16.8 (d, 2JCP ) 3 Hz, PCHMeMe), 17.4 (s, PCHMeMe), 18.8
(pt, J*CP ≈ 8 Hz, PCHMe2), 19.6 (s, PCHMeMe), 19.9 (s,
PCHMeMe), 20.0 (s, PCHMeMe), 20.7 (pt, J*CP ≈ 19 Hz, CH2),
3
7.54 (d, 2H, JHH ) 7.8 Hz, CarHo). 13C{1H} NMR (C6D6, 75
1
3
1
MHz): δ -1.7 (dd, 2JCP ) 73 and 37 Hz, Ni-CH3), 17.1 (dd, 1JCP
23.6 (dd, JCP ) 15 Hz, JCP ) 6 Hz, PCHMe2), 24.0 (dd, JCP
)
3
1
3
2
2
11 Hz, JCP ) 5 Hz, PCHMe2), 24.3 (dd, JCP ) 18 Hz, JCP ) 3
Hz, PCHMe2), 24.8 (pt, J*CP ≈ 3 Hz, PCHMe2), 62.7 (s, PhCH2Nd
CHPh), 74.0 (d, 2JCP ) 15 Hz, PhCH2NdCHPh), 121.6 (s, CarHp),
124.1 (s, CarHo), 125.5 (s, CarHp), 126.7 (s, CarHo), 127.9 (s, CarHm),
145.3 (s, Car), 149.0 (s, Car). 31P{1H} NMR (C6D6, 121 MHz): δ
) 19 Hz, JCP ) 14 Hz, CH2), 17.6 (s, PCHMeMe), 18.2 (d, JCP
) 3 Hz, PCHMeMe), 18.9 (s, PCHMeMe), 19.8 (s, PCHMeMe),
23.0 (pt, J*CP ≈ 22 Hz, CH2), 25.0 (s, PCHMe2), 25.7 (s,
NCH2CH2), 48.2 (s, NCH2CH2), 116.5 (s, CarHp), 123.5 (s, CarHo),
153.8 (s, Car), 162.2 (s, NCO). 31P{1H} NMR (C6D6, 162 MHz):
δ 61.9, 78.0. Compound 17′: Anal. Calcd for C37H62N4O2NiP2:
C, 62.11; H, 8.73; N, 7.83. Found: C, 62.19; H, 8.80; N, 7.81. IR
(Nujol mull): ν(N-CdO) 1659, 1595 cm-1. 1H NMR (C6D6, 400
2
67.5 (d, JPP ) 69 Hz), 68.7 (d).
Synthesis of Ni(dippe)(CH3)(OC(O)NC4H8) (15). A solution
of lithium pyrrolidinide (26 mg, 0.35 mmol) in 3 mL of THF was
added to a cooled solution (-78 °C) of Ni(dippe)(Me)(F) (124 mg,
0.35 mmol) in 2 mL of THF. After removing the cooling bath,
dry CO2 was bubbled through the resulting solution for 5 min. The
volatiles were removed in Vacuo, and the residue was extracted
with 2 mL of diethyl ether. Evaporation to dryness afforded the
3
MHz): δ 0.41 (d, 3H, JHP ) 1.7 Hz, Ni-CH3), 0.82 (m, 2H,
3
3
PCHMeMe), 0.89 (dd, 6H, JHP ) 12.5 Hz, JHH ) 6.7 Hz,
PCHMeMe), 1.02 (m, 6H, PCHMeMe), 1.27 (m, 12H, PCHMeMe),
3
1.66 (m, 2H, PCHMe2), 1.76 (m, 2H, PCHMe2), 1.28 (t, 4H, JHH
) 3.0 Hz, NCH2CH2), 1.40 (t, 4H, JHH ) 6.6 Hz, NCH2CH2),
3.05 (s, 4H, NCH2CH2), 3.52 (s, 4H, NCH2CH2), 6.56 (bs, 1H,
3
1
product as an orange oil. H NMR (C6D6, 300 MHz): δ 0.47 (s,
3
3
3
3
NH), 6.81 (t, 1H, JHH ) 7.2 Hz, CarHp), 6.92 (t, 1H, JHH ) 7.3
3H, Ni-CH3), 0.86 (dd, 6H, JHP ) 13.0 Hz, JHH ) 6.9 Hz,
Hz, CarHp), 7.23 (t, 2H, 3JHH ) 7.9 Hz, CarHm), 7.27 (t, 2H, 3JHH
)
3
3
PCHMeMe), 1.03 (dd, 6H, JHP ) 11.8 Hz, JHH ) 7.1 Hz,
3
3
3
7.8 Hz, CarHm), 7.59 (d, 2H, JHH ) 7.6 Hz, CarHo), 7.84 (d, 2H,
PCHMeMe), 1.15 (dd, 6H, JHP ) 15.6 Hz, JHH ) 7.1 Hz,
3JHH ) 8.3 Hz, CarHo). 13C{1H} NMR (C6D6, 100 MHz): δ -1.2
3
3
PCHMeMe), 1.43 (dd, 6H, JHP ) 15.0 Hz, JHH ) 7.0 Hz,
PCHMeMe), 1.69 (m, 2H, PCHMe2), 2.05 (m, 2H, PCHMe2), 1.57
(s, 4H, NCH2CH2), 3.71 (s, 4H, NCH2CH2). 13C{1H} NMR (C6D6,
75 MHz): δ 1.2 (dd, 2JCP ) 71 and 34 Hz, Ni-CH3), 16.4 (dd, 1JCP
2
1
2
(dd, JCP ) 71 and 34 Hz, Ni-CH3), 16.4 (dd, JCP ) 19 Hz, JCP
) 11 Hz, CH2), 18.0 (s, PCHMeMe), 18.2 (s, PCHMeMe), 19.2
2
2
(d, JCP ) 5 Hz, PCHMeMe), 19.7 (d, JCP ) 2 Hz, PCHMeMe),
23.6 (t, JCP ) 23 Hz, CH2), 24.3 (d, 1JCP ) 14 Hz, PCHMe2), 25.4
2
) 19 Hz, JCP ) 11 Hz, CH2), 18.0 (s, PCHMeMe), 18.2 (s,
1
PCHMeMe), 19.2 (d, 2JCP ) 5 Hz, PCHMeMe), 19.7 (d, 2JCP ) 2
(d, JCP ) 28 Hz, PCHMe2), 25.7 (s, NCH2CH2), 26.1 (s,
1
NCH2CH2), 45.8 (s, NCH2CH2), 48.8 (s, NCH2CH2), 117.2 (s,
CarHp), 119.7 (s, CarHp), 122.3 (s, CarHo), 124.0 (s, CarHo), 141.4
(s, Car), 154.1 (s, NCO), 154.3 (s, Car), 162.8 (s, NCO). 31P{1H}
NMR (C6D6, 162 MHz): δ 61.9, 78.1.
Hz, PCHMeMe), 23.6 (t, JCP ) 23 Hz, CH2), 24.3 (d, JCP ) 14
1
Hz, PCHMe2), 25.4 (d, JCP ) 28 Hz, PCHMe2), 26.1 (s,
NCH2CH2), 46.9 (bs, NCH2CH2), 161.2 (s, OCO). 31P{1H} NMR
(C6D6, 162 MHz): δ 64.8, 77.7.
Synthesis of Ni(dippe)(CH3)(SC(NPh)OtBu) (18). A solution
of lithium tert-butoxide (0.30 mmol) in 3 mL of THF was added
to a cooled solution (-78 °C) of Ni(dippe)(Me)(F) (106 mg, 0.30
mmol) in 3 mL of THF. The reaction mixture was allowed to reach
room temperature and then cooled again at -78 °C. Then 36 µL
(0.30 mmol) of PhNCS was added and the resulting solution stirred
for 4 h at room temperature. The volatiles were removed under
vacuum, and the solid was extracted with 5 mL of Et2O. Orange
crystals of product 18 were obtained in a 45% yield after
concentrating and cooling this solution. Anal. Calcd for C26H49-
NONiSP2: C, 57.36; H, 9.07; N, 2.57. Found: C, 56.89; H, 8.77;
N, 2.60. IR (Nujol mull): ν(S-CdN) 1584 cm-1. 1H NMR (C6D6,
t
Synthesis of Ni(dippe)(CH3)(N(Ph)CO2 Bu) (16). A solution
of lithium tert-butoxide (0.35 mmol) in 3 mL of THF was added
to a cooled solution (-78 °C) of Ni(dippe)(Me)(F) (125 mg, 0.35
mmol) in 3 mL of THF. The reaction mixture was allowed to reach
room temperature and then cooled again at -78 °C. Then 38 µL
(0.35 mmol) of PhNCO was added and the resulting solution stirred
for 15 min at room temperature. The volatiles were removed under
vacuum, and the solid was extracted with 3 mL of Et2O. Orange
crystals of product 16 were obtained in 53% yield by concentrating
and cooling this solution at -20 °C. Anal. Calcd for C26H49NO2-
NiP2: C, 59.11; H, 9.35; N, 2.65. Found: C, 58.51; H, 8.68; N,
1
2.69. IR (Nujol mull): ν(N-CdO) 1634 cm-1. H NMR (C6D6,
300 MHz): δ 0.51 (dd, 3H, 3JHP ) 6.6 and 4.3 Hz, Ni-CH3), 0.73
300 MHz): δ 0.10 (dd, 3H, 3JHP ) 6.5 and 4.7 Hz, Ni-CH3), 1.00
3
3
3
(m, 12H, PCHMeMe), 0.90 (m, 2H, CH2), 1.00 (dd, 6H, JHP
)
(bs, 12H, PCHMeMe), 1.26 (dd, 6H, JHP ) 13.2 Hz, JHH ) 7.0
3
3
3
3
15.8 Hz, JHH ) 7.3 Hz, PCHMeMe), 1.08 (dd, 6H, JHP ) 15.4
Hz, PCHMeMe), 1.40 (dd, 6H, JHP ) 15.5 Hz, JHH ) 7.2 Hz,
PCHMeMe), 2.26 (m, 4H, PCHMe2), 1.51 (s, 9H, C(CH3)3), 6.74
(t, 1H, 3JHH ) 7.3 Hz, CarHp), 7.11 (t, 2H, 3JHH ) 7.8 Hz, CarHm),
3
Hz, JHH ) 7.2 Hz, PCHMeMe), 1.82 (s, 9H, C(CH3)3), 6.97 (t,
1H, 3JHH ) 7.1 Hz, CarHp), 7.35 (m, 4H, CarHo + CarHm). 13C{1H}
2
7.83 (d, 2H, JHH ) 7.3 Hz, CarHo). 13C{1H} NMR (C6D6, 75
3
NMR (C6D6, 75 MHz): δ -3.6 (dd, JCP ) 62 and 31 Hz, Ni-
CH3), 18.0 (s, PCHMeMe), 19.1 (d, 2JCP ) 4 Hz, PCHMeMe), 19.4
(s, PCHMeMe), 19.6 (s, PCHMeMe), 22.9 (t, JCP ) 22 Hz, CH2),
24.5 (d, 1JCP ) 18 Hz, PCHMe2), 25.2 (d, 1JCP ) 25 Hz, PCHMe2),
28.8 (s, C(CH3)3), 79.8 (s, C(CH3)3), 120.7 (s, CarHp), 122.9 (s,
CarHm), 128.4 (s, CarHo), 152.7 (s, Car), 166.1 (s, SCN). 31P{1H}
MHz): δ -2.1 (dd, 2JCP ) 71 and 37 Hz, Ni-CH3), 17.0 (dd, 1JCP
2
) 19 Hz, JCP ) 12 Hz, CH2), 18.7 (s, PCHMeMe), 20.1 (s,
PCHMeMe), 23.8 (pt, J*CP ≈ 22 Hz, CH2), 25.7 (d, 1JCP ) 28 Hz,
PCHMe2), 29.5 (s, C(CH3)3), 76.1 (s, C(CH3)3), 119.2 (s, CarHp),
125.7 (s, CarHo), 127.5 (s, CarHm), 152.1 (s, Car), 159.0 (s, NCO2C-
(CH3)3). 31P{1H} NMR (C6D6, 20 °C, 121 MHz): δ 62.2, 75.9.
2
NMR (C6D6, 121 MHz): δ 72.5 (d, JPP ) 20 Hz), 80.0 (d).
Synthesis of Ni(dippe)(CH3)(N(Ph)C(O)NC4H8) (17). A solu-
tion of 0.35 mmol of complex 6 was generated at -78 °C as
described above. Addition of 38 µL (0.35 mmol) of PhNCO to the
reaction mixture caused an immediate color change from dark red
to dark orange. After the solution reached room temperature, solvent
Synthesis of Ni(dippe)(CH3)(SC(NPh)NC4H8) (19). Addition
of 37 µL (0.35 mmol) of PhNCS to a cooled (-78 °C) THF solution
containing 0.35 mmol of complex 6 caused an immediate color
change from dark red to dark orange. After the solution reached
room temperature, solvent was removed under reduced pressure,

Monomeric Alkoxo and Amido Methylnickel(II) Complexes
Organometallics, Vol. 26, No. 15, 2007 3849
Table 1. Crystal and Refinement Data for Compounds 7, 12, 13, and 19
7
12
13
19
empirical formula
fw
C16H38NiOP2
367.11
C23H45NNiP2
456.25
C18H39NNiP2
390.15
C26H48N2NiP2S
541.37
temperature, K
cryst syst
space group
a, Å
b, Å
c, Å
100(2)
triclinic
P1h
100(2)
monoclinic
P21
8.9113(6)
14.9674(8)
10.0496(6)
90
111.331(2)
90
1248.58(13)
2
1.214
0.913
496
100(2)
triclinic
P1h
293(2)
triclinic
P1h
7.9694(6)
14.1687(11)
17.4841(14)
92.906(2)
95.309(2)
90.651(2)
1963.0(3)
4
9.7279(7)
14.9737(9)
c15.2632(11)
80.308(2)
77.419(2)
79.294(2)
2113.1(3)
4
10.3613(16)
10.3787(16)
14.333(2)
100.194(2)
93.297(2)
99.191(2)
1491.7(4)
2
R, deg
â, deg
γ, deg
volume, Å3
Z
calcd density, g/cm3
absorp coeff, mm-1
F(000)
1.242
1.147
800
1.226
1.068
848
1.205
0.843
584
no. of reflns collected
no. of indep reflns
no. of params refined
final R1(F) indexa [[F2 > 2σ(F2)]
wR2(F2) indexb (all data)
Sc (all data)
30 564
11 798 [R(int) ) 0.0454]
361
0.0499
0.1510
1.041
13 396
7144 [R(int) ) 0.0364]
245
0.0467
0.1134
0.998
32 087
12 759 [R(int) ) 0.0327]
397
0.0427
0.1287
1.117
15 881
6955 [R(int) ) 0.0223]
350
0.0585
0.2087
0.902
absolute struct param
0.023(12)
b
2
2
2
c
2
2
a R1(F) ) ∑(|Fo| - |Fc|)/∑|Fo| for the observed reflections [F2 > 2σ(F2)]. wR2(F2) ) {∑[w(Fo - Fc )2]/∑w(Fo )2}1/2. S ) {∑[w(Fo - Fc )2]/(n -
p)}1/2 (n ) number of reflections, p ) number of parameters).
and the resulting residue was extracted with 3 mL of THF.
Concentration and cooling at -20 °C gave orange crystals of the
product in 55% yield. Anal. Calcd for C25H44N2NiSP2: C, 57.16;
H, 8.44; N, 5.33. Found: C, 56.95; H, 8.41; N, 4.93. IR (Nujol
mull): ν(S-CdN) 1539 cm-1. 1H NMR (C6D6, 300 MHz): δ 0.24
mounted on a glass fiber using perfluoropolyether oil (FOMBLIN
140/13, Aldrich) in the cold N2 stream of a low-temperature device
attachment (7, 12, and 13) or using a glue (19). A summary of
crystallographic data is reported in Table 1. Intensity data for
complexes 7, 12, and 13 were collected on a Bruker-AXS X8Kappa
diffractometer equipped with an Apex-II CCD area detector, using
a graphite monochromator Mo KR1 (λ ) 0.71073 Å) and a Bruker
Cryo-Flex low-temperature device. The data of compound 19 were
collected at rt on a Bruker AXS SMART 1000 single-crystal
diffractometer equipped with an area detector using graphite-
monochromated λ(Mo KR1) ) 0.71073 Å radiation. A semiempirical
absorption correction was applied (SADABS).35 The structures were
solved by direct (SIR-2002)36 and Patterson methods and refined
against all F2 data by full-matrix least-squares techniques (SHELXTL-
6.12).37 All the non-hydrogen atoms were refined with anisotropic
displacement parameters. The hydrogen atoms were introduced into
the geometrically calculated positions and refined riding on the
corresponding parent atoms.
3
(d, 3H, JHP ) 2.3 Hz, Ni-CH3), 0.77 (m, 2H, PCHMeMe), 0.99
3
3
(dd, 6H, JHP ) 14.9 Hz, JHH ) 6.6 Hz, PCHMeMe), 0.93 (m,
3
3
2H, CH2), 1.15 (dd, 6H, JHP ) 14.5 Hz, JHH ) 6.4 Hz,
PCHMeMe), 1.65 (t, 4H, 3JHH ) 6.3 Hz, NCH2CH2), 1.82 (m, 4H,
3
PCHMeMe), 4.02 (t, 4H, JHH ) 6.3 Hz, NCH2CH2), 6.98 (t, 1H,
3JHH ) 7.2 Hz, CarHp), 7.36 (t, 2H, 3JHH ) 7.7 Hz, CarHm), 7.49 (d,
2H, JHH ) 7.9 Hz, CarHo). 13C{1H} NMR (C6D6, 75 MHz): δ
3
2
-2.9 (dd, JCP ) 61 and 31 Hz, Ni-CH3), 18.1 (s, PCHMeMe),
19.1 (s, PCHMeMe), 19.6 (s, PCHMeMe), 22.8 (t, JCP ) 22 Hz,
CH2), 24.5 (d, JCP ) 17 Hz, PCHMe2), 25.3 (d, JCP ) 25 Hz,
PCHMe2), 25.8 (s, NCH2CH2), 49.3 (bs, NCH2CH2), 119.3 (s,
1
1
3
CarHp), 124.4 (s, CarHo), 155.7 (s, Car), 160.2 (d, JCP ) 15 Hz,
SCN). 31P{1H} NMR (C6D6, 121 MHz): δ 73.4 (d, 2JPP ) 11 Hz),
80.4 (d).
Acknowledgment. Financial support from the DGI (Project
CTQ2006-05527/BQU) and Junta de Andaluc´ıa (Project P06-
FQM-01704) is gratefully acknowledged. I.M. acknowledges a
research fellowship from the Consejo Superior de Investiga-
ciones Cient´ıficas (I3P program).
X-ray Crystal Structure Analyses of 7, 12, 13, and 19. A single
crystal, of each representative compound, of suitable size was
(35) Sheldrick, G. SADABS; Bruker AXS, Inc.: Madison, WI, 1999.
(36) Burla, M. C.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.;
Giacovazzo, C.; Polidori, G.; Spagna, R. SIR2002: the program. J. Appl.
Crystallogr. 2003, 36, 1103.
(37) (a) SHELXTL 6.14; Bruker AXS, Inc.: Madison, WI, 2000-2003.
(b) Sheldrick, G. M. SHELX-97, Programs for Crystal Structure Analysis
(release 97-2); Institu¨t fu¨r Anorganische Chemie der Universita¨t: Go¨ttingen,
Germany, 1998.
Supporting Information Available: X-ray crystallographic file
in CIF format is available free of charge via the Internet at
http://pubs.acs.org.
OM7002909