Nickel(II) complexes containing bidentate amido phosphine ligands derived from α-iminophosphorus ylides: Synthesis and structural characterization

Article abstract of DOI:10.1021/ic701836j

The reactions of prop-2-ynyltriphenylphosphonium bromide with a series of primary aromatic or aliphatic amines in refluxing acetonitrile generated the corresponding 2-hydrocarbylaminoprop-1-enyltriphenylphosphonium bromide [RNHC(Me)=CHPPh₃]⁺Br^- (R = 2,6-C ₆H₃Pr₂ (1a), 2,6-C₆H ₃Me₂ (1b), Ph (1c), t-Bu (1d)) as crystalline solids. Deprotonation of 1a-d with NaH in THF at -35 °C afforded the α-iminophosphorus ylides RN=C(Me)CH=PPh₃ (2a-d) in high yield. Spectroscopic and crystallographic data of 2 suggest a strong intramolecular interaction between the imino nitrogen and the phosphorus atom. In contrast to N-arylated 2a-c, the W-fert-butyl-derived 2d is extremely moisture-sensitive. Hydrolysis of 2d led to elimination of benzene and generated concomitantly the phosphine oxide 3d that contains an ene-amine functionality. The reactions of 2a-c with Ni(COD)₂ in the presence of an excess amount of pyridine in toluene produced the divalent nickel complexes of the type [K ²-RNC(Me)=CHPPh₂]-Ni(Ph)(Py) (4a-c). The solution and solid-state structures of these new compounds are presented.

Full text of DOI:10.1021/ic701836j

Inorg. Chem. 2008, 47, 749−758
Nickel(II) Complexes Containing Bidentate Amido Phosphine Ligands
Derived from -Iminophosphorus Ylides: Synthesis and Structural
Characterization
r
Pei-Ying Lee and Lan-Chang Liang*
Department of Chemistry and Center for Nanoscience and Nanotechnology, National Sun Yat-sen
UniVersity, Kaohsiung 80424, Taiwan
Received September 17, 2007
The reactions of prop-2-ynyltriphenylphosphonium bromide with a series of primary aromatic or aliphatic amines in
refluxing acetonitrile generated the corresponding 2-hydrocarbylaminoprop-1-enyltriphenylphosphonium bromide
i
[RNHC(Me)
Deprotonation of 1a
(2a d) in high yield. Spectroscopic and crystallographic data of 2 suggest a strong intramolecular interaction between
the imino nitrogen and the phosphorus atom. In contrast to N-arylated 2a c, the N-tert-butyl-derived 2d is extremely
moisture-sensitive. Hydrolysis of 2d led to elimination of benzene and generated concomitantly the phosphine
oxide 3d that contains an ene-amine functionality. The reactions of 2a c with Ni(COD)2 in the presence of an
excess amount of pyridine in toluene produced the divalent nickel complexes of the type [ CHPPh2]-
2-RNC(Me)
Ni(Ph)(Py) (4a c). The solution and solid-state structures of these new compounds are presented.
d
CHPPh3]+Br- (R
d with NaH in THF at
)
2,6-C6H3 Pr2 (1a), 2,6-C6H3Me2 (1b), Ph (1c), t-Bu (1d)) as crystalline solids.
−
−35 °C afforded the R-iminophosphorus ylides RNdC(Me)CHdPPh3
−
−
−
κ
d
−
Scheme 1
Introduction
Functionalized phosphorus ylides are appealing as they
facilitate the preparation of not only functionalized olefinic
molecules but also coordination and organometallic com-
plexes that may serve as catalytic initiators for specific
chemical transformations.1-6 One remarkable precedent in
this regard is the nickel(II)-based catalysts for the Shell
higher olefin process (SHOP) derived from R-ketophosphorus
ylides Ph3PdCRC(O)R′.7,8 It has been shown that the
oxidative addition of zero-valent nickel species such as Ni-
(COD)2 (COD ) cycloocta-1,5-diene) with Ph3PdCRC(O)-
R′ in the presence of a two-electron donor (L; e.g., PPh3)
generated divalent nickel complexes [Ph2PCRdC(R′)O]-
NiPh(L) that contain a monoanionic bidentate phosphine
enolate ligand. Extensive research has subsequently been
directed to the development of new SHOP-type catalysts by
modifying the monoanionic bidentate ligands.9 Representa-
tive examples reminiscent of that of [Ph2PCRdC(R′)O]NiPh-
(L) include [O-N]-,10-19 [N-N]-,20-26 [N-P]-,27-33 and
modified [O-P]-,34-43 etc.
* To whom correspondence should be addressed. E-mail: lcliang@
mail.nsysu.edu.tw. Fax: +886-7-5253908.
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We are currently investigating the exploratory chemistry
involving metal complexes of chelating amido phosphine
ligands.44-50 In particular, a series of nickel(II) alkyl
complexes supported by bidentate diarylamido phosphine
ligands have been synthesized and structurally character-
ized.51 The incorporation of the rigid and robust o-phenylene
backbone in the ligand design is beneficial in view of the
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10.1021/ic701836j CCC: $40.75
Published on Web 12/15/2007
© 2008 American Chemical Society
Inorganic Chemistry, Vol. 47, No. 2, 2008 749

Lee and Liang
Scheme 2
Figure 1. Possible isomeric structures of 2-aminoprop-1-enyltriph-
enylphosphonium bromide (1a-d).
enhanced thermal stability of the derived metal complexes.52-55
In an effort to expand the territory of amido phosphine
chemistry and our general interests in metal-mediated chemi-
cal transformations, we aim to prepare transition metal
complexes that contain an olefinic linkage to connect the
amido nitrogen and the phosphorus donors. The sp2-hybrid-
ized olefinic carbon atoms should in principle offer the
rigidity similar to that of the o-phenylene counterparts. Our
strategy to prepare such complexes of divalent nickel
involves oxidative addition of Ni(COD)2 with R-iminophos-
phorus ylides, in analogy with that of the established SHOP
catalysts. To this end, we have set out to prepare a series of
N-substituted R-iminophosphorus ylides and explore their
subsequent reactivity with Ni(COD)2. Remarkably, the
spectroscopic and crystallographic data of these functional-
ized phosphorus ylides are all indicative of a strong intramo-
lecular, noncovalent interaction between the imino nitrogen
and the phosphorus atom. In this Article, we describe the
preparation and structural characterization of these R-imi-
nophosphorus ylides and the divalent nickel complexes
derived thereafter. Spectroscopic data and molecular struc-
tures of these compounds are discussed.
Results and Discussion
Preparation and Characterization of N-Substituted
r-Iminophosphorus Ylides. Scheme 1 summarizes the
synthetic protocol. The starting material prop-2-ynyltriph-
enylphosphonium bromide was readily prepared following
the literature procedures from the reaction of triphenylphos-
phine with propargyl bromide in the presence of aqueous
hydrobromic acid in 1,4-dioxane at room temperature.56,57
Subsequent reactions with a number of primary aromatic or
aliphatic amines in refluxing acetonitrile generated high yield
of the corresponding 2-hydrocarbylaminoprop-1-enyltriph-
enylphosphonium bromide [RNHC(Me)dCHPPh3]+Br- (R
i
) 2,6-C6H3 Pr2 (1a), 2,6-C6H3Me2 (1b), Ph (1c), t-Bu (1d))
as crystalline solids. The hydroamination reactions are highly
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750 Inorganic Chemistry, Vol. 47, No. 2, 2008

r-Iminophosphorus Ylides and the Ni(II) Complexes
Figure 2. Molecular structures of 1a, 1b, and 1d with thermal ellipsoids drawn at the 35% probability level. Selected bond distances and angles are listed
in Supporting Information.
Figure 3. Molecular structures of 2a and 2c with thermal ellipsoids drawn at the 35% probability level. Selected bond distances and angles are listed in
Supporting Information.
Scheme 3
of 1a and 1b indicate that the o-alkyl groups are chemically
equivalent. The isopropylmethyl groups in 1a are observed
as two doublet resonances in the H NMR spectrum. The
t
1
Figure 4. Molecular structure of BuNHC(Me)dCHP(O)Ph2 (3d) with
thermal ellipsoids drawn at the 35% probability level. Selected bond
distances and angles are listed in Supporting Information.
solid-state structures of 1a, 1b, and 1d were also confirmed
by X-ray diffraction studies, which revealed a trans geometry
for the two hetero substituents in these internal olefins (Figure
2), consistent with that deduced from the solution NMR
spectroscopic data. Though not observed spectroscopically,
the terminal olefinic isomer (Figure 1) is presumably the
kinetic product that subsequently transforms into internal
1a-d thermodynamically.
regioselective, leading to the exclusive formation of 2-amino-
substituted derivatives. No other regioisomer was detected.
The NMR spectroscopic data of 1a-d are all indicative of
the presence of an internal CdC moiety instead of an
isomeric terminal olefin or ketimine functionality (Figure 1).
The diagnostic olefinic hydrogen atom is observed in the
1H NMR spectra of 1a-d as a doublet resonance at ca. 3.5
ppm (2JHP ) 16 Hz) and the acidic NH proton at ca. 8-10
ppm (4JHP ) 4 Hz). The allylic CH3 atoms appear as a singlet
resonance at ca. 2.1 ppm. The 31P{1H} NMR spectra exhibit
a singlet resonance at ca. 17 ppm for these molecules. The
relatively low 3JCP of ca. 5 Hz observed in the 13C{1H} NMR
spectra for the phosphorus atom and the allylic carbon is
suggestive of a cis geometry for these nuclei with respect to
the CdC bond, consistent with what would be anticipated
for steric reasons. The 1H and 13C NMR spectroscopic data
Deprotonation of 1a-d with NaH in THF at -35 °C
produce the desired R-iminophosphorus ylides 2a-d. The
1H NMR spectra of these molecules reveal a doublet
resonance at ca. 3.0 ppm for the characteristic ylidic proton
2
CHdPPh3 with JHP of ca. 26 Hz, a coupling constant that
is notably larger than those corresponding to the olefinic
methine moiety in 1a-d. The 31P chemical shifts of ca. 13
ppm found for 2a-d are relatively upfield as compared to
those of 1a-d. Interestingly, the 3JCP coupling constants of
ca. 16 Hz between the phosphorus atom and the methyl
carbon R to the imino group are significantly large as
Inorganic Chemistry, Vol. 47, No. 2, 2008 751

Lee and Liang
Scheme 4
Csp2 double bond distance (1.34 Å).59 The C-N distances
of 2 (ca. 1.30 Å) are slightly shorter than those of 1 (ca.
1.34 Å), so are the C-P lengths (2, ca. 1.70 Å; 1, ca. 1.74
Å). These results are consistent with what we formulate in
Scheme 2, in which the π electrons delocalize throughout
Scheme 5
the heterobutadiene backbone. Consistently, the N-Csp2
-
Csp2-P atoms are nearly coplanar as evidenced by the mean
deviation value of 0.0115 Å for 2a and 0.0069 Å for 2c.
Notably, the N-P distances of 3.013 Å for 2a and 2.832 Å
for 2c are smaller than the sum of the van der Waals radius
of N and P of 3.40 Å,60 indicating a noncovalent interaction
between the two heteroatoms. Similar observation has also
been reported for R-carbonyl-functionalized phosphorus
ylides61 and an ester-functionalized iminophosphorus ylide.62
Consistent with the steric hindrance of the N-substituents,
the N-Csp2-Csp2 and Csp2-Csp2-P bond angles of 2a are
both wider than those of 2c by ca. 4°, and the N-P distance
of the former is longer than that of the latter. The N-aryl
compared to the corresponding values in 1a-d (vide supra),
suggesting that these two nuclei are positioned mutually trans
in a cisoid heterobutadiene molecule. As a result, the two
sterically demanding hetero substituents in 2a-d are mutu-
ally cis. Such geometry is apparently unusual in view of the
steric hindrance imposed by these bulky substituents but
likely indicative of a strong 1,4-intramolecular, noncovalent
interaction between the imino nitrogen and the phosphorus
atom due to the zwitterionic nature arising from the delo-
calization of π electrons in these heterobutadiene molecules
as illustrated in Scheme 2. The discrepancy in the geometric
preferences found for 2a-d and 1a-d, respectively, high-
lights particularly the presence of such intramolecular
interaction in the former. The absence of the 1,4-N‚‚‚P
interaction in 1a-d is presumably ascribed to the relatively
insufficient electronegative nature of the amine nitrogen atom
as compared to that of imine and the profound electrostatic
interaction of the cationic phosphorus atom with the anionic
bromide rather than the neutral amine. Similar to what has
been observed for 1a, the two isopropyl substituents of the
N-aryl ring in 2a are chemically equivalent and the isopro-
pylmethyl groups are observed as two doublet resonances
ring of 2a is approximately perpendicular to the N-Csp2
Csp2-P mean plane with the dihedral angle of 89.6°;
however, that of 2c is tilted with respect to the N-Csp2
-
-
Csp2-P mean plane with the dihedral angle of 52.9° due
likely to the absence of sterically demanding o-alkyl sub-
stituents.
Unlike 2a-c, the N-tert-butyl-derived 2d is viscous oil
and tends to be more sensitive to moisture. Attempts to
crystallize this compound from a variety of solvents were
not successful. Instead, it reacts with the trace amount of
moisture present in the solvents employed for crystallization
to produce in low yield a crystalline solid 3d that is
characteristic of an ene-amine-functionalized phosphine oxide
(Scheme 3). The 31P{1H} NMR spectrum of this molecule
exhibits a singlet resonance at 21.4 ppm, a value that is
shifted relatively downfield from those of 1d and 2d. The
1H NMR spectrum displays a doublet resonance at 4.66 ppm
with 2JHP of 19 Hz for the olefinic proton and a broad singlet
resonance at 5.37 ppm for NH. The relatively low inter-
1
in the H NMR spectrum.
The solid-state structures of 2a and 2c were established
by X-ray diffraction analysis. As depicted in Figure 3, the
imino and the phosphorus ylidic functionalities are mutually
cis with respect to the Csp2-Csp2 bond, consistent with the
result derived from the solution NMR studies. The Csp2
-
Csp2 distances of 2a (1.412(4) Å) and 2c (1.418(4) Å) are
relatively shorter than the typical value of 1.478 Å for a
Csp2-Csp2 single bond,58 but comparatively longer than the
corresponding distances of 1 (ca. 1.36 Å) and a typical Csp2d
(59) Zumdahl, S. S. Chemical Principles, 5th ed.; Houghton Mifflin
Company, 2006.
(60) Bondi, A. J. Chem. Phys. 1964, 68, 441.
(61) Lledos, A.; Carbo, J. J.; Urriolabeitia, E. P. Inorg. Chem. 2001, 40,
4913-4917.
(62) Falvello, L. R.; Gines, J. C.; Carbo, J. J.; Lledos, A.; Navarro, R.;
Soler, T.; Urriolabeitia, E. P. Inorg. Chem. 2006, 45, 6803-6815.
(58) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, 685, S1-S19.
752 Inorganic Chemistry, Vol. 47, No. 2, 2008

r-Iminophosphorus Ylides and the Ni(II) Complexes
Figure 5. Molecular structures of 4a, 4b, and 4c with thermal ellipsoids drawn at the 35% probability level. Selected bond distances and angles are listed
in Supporting Information.
nuclear coupling constant of 7 Hz between the phosphorus
atom and the allylic carbon atom is suggestive of a cis
geometry for these two nuclei with respect to the CdC bond
in this molecule, reminiscent of what has been observed for
1d rather than 2d. The amino group is thus trans to the
phosphine oxide functionality in this olefinic molecule.
Consistent with this result, an X-ray diffraction study of 3d
(Figure 4) also verified the trans relationship between the
N-tert-butyl group and the OdPPh2 moiety. The CdC bond
distance of 1.371 (5) Å in 3d is similar to those found for
1a, 1b, and 1d. With the presence of both NH and OdPPh2
functionalities, intermolecular hydrogen bonding is found in
the lattice of 3d.
Scheme 4 illustrates a plausible mechanism for the
transformation of 2d to 3d. With the zwitterionic charac-
teristic, the R-iminophosphorus ylides 2 should be prone to
association with a water molecule as a result of intermo-
lecular dipole-dipole interaction. The water adduct thus
formed, though in low concentration due to the limited
availability of moisture present in the solvents employed, is
presumably in equilibrium with the R-iminophosphorus
ylides 2. In contrast to the N-arylated 2a-c, the N-tert-butyl-
derived 2d is nucleophilic/basic enough to react irreversibly
with water as a consequence of the enhanced electron-
releasing nature of the N-tert-butyl group in the latter. A
concerted process is presumably involved in the water adduct
of 2d for the cleavage of P-Ph and O-H bonds as well as
the formation of N-H, PdO, and Ph-H bonds, leading to
the concomitant generation of a benzene molecule and the
presumed kinetic product 3d′, which subsequently isomerizes
to the thermodynamically more favorable 3d for steric
reasons. The identity of the liberated benzene was confirmed
by GC, and the yield (relative to m-xylene as an internal
standard) was virtually equivalent to the (sub)stoichiometry
of the water added in controlled experiments. Perhaps
phenomenal in this process is the water-mediated P-Ph bond
activation under extremely mild conditions.63,64
a complicated mixture, from which no desired product could
be effectively purified. Similar results have also been reported
for systems employing PhNdC(Ph)CHdPPh3,29 which led
unexpectedly to the formation of the ylidic complex [κ2-Ph2-
PCHdC(Ph)(NPh)]Ni(Ph)[PhNdC(Ph)CHdPPh3] regardless
of the identity of the Lewis base (e.g., PPh3, PMe3, pyridine,
etc.) involved. Interestingly, addition of an excess amount
of pyridine to a mixture of 2a-c and Ni(COD)2 in toluene
effectively generated red crystals of the corresponding
divalent nickel complexes [κ2-RNC(Me)dCHPPh2]Ni(Ph)-
(Py) (4a-c) (Scheme 5). Though it seems not atypical in
view of the established SHOP chemistry, the phenyl group
transfer from the phosphorus atom in 2a-c to nickel is
somewhat analogous, at least in part, to that from 2d to the
acidic proton as illustrated in Scheme 4. No ylidic complex
similar to [κ2-Ph2PCHdC(Ph)(NPh)]Ni(Ph)[PhNdC(Ph)-
CHdPPh3]29 was detected. Parallel experiments employing
2d, however, gave intractable materials that could not be
identified.
The 31P{1H} NMR spectra of 4a-c exhibit a singlet
resonance at ca. 31 ppm, which is relatively downfield shifted
from those of the corresponding 1 and 2 but comparable to
those of diarylamido phosphine complexes of nickel(II) such
as [iPr-NP]NiPh(PMe3) (33 ppm; [iPr-NP]- ) N-(2-
diphenylphosphinophenyl)-2,6-diisopropylanilide).51 The ole-
finic proton of 4a-c is observed as a doublet resonance at
2
ca. 3.8 ppm with JHP of ca. 2 Hz. Consistent with the
anticipated trans geometry of the allylic carbon with respect
3
to the phosphorus donor, the JCP values of ca. 17 Hz for
these molecules are considerably large and similar to those
of the corresponding 2 rather than 1. Analogous to those of
1a and 2a, the isopropyl groups in 4a are chemically
equivalent and the isopropylmethyl moieties are observed
1
as two doublet resonances in the H NMR spectrum.
Figure 5 illustrates the molecular structures of 4a-c. As
anticipated, the Csp2-Csp2 distances of ca. 1.36 Å found in
the backbone of 4a-c are comparable to those of the
corresponding 1 rather than 2, so are the C-N and C-P
bond lengths. The nickel center lies virtually on the square
plane defined by the four donor atoms with the slight
displacement of nickel from the mean coordination plane
by 0.0262 Å for 4a, 0.0206 Å for 4b, and 0.0094 Å for 4c.
Reminiscent of that of the SHOP catalyst [Ph2PCHdC(Ph)O]-
Ni(Ph)(PPh3),7,8 the phenyl group is cis to the phosphorus
donor with the P-Ni-Cipso angles of 88.39(12)° (4a), 90.64-
(14)° (4b), and 92.02(14)° (4c). The coordinated pyridine
Reactions of N-Substituted r-Iminophosphorus Ylides
with Ni(COD)2. In contrast to what has been reported for
the SHOP catalysts derived from Ph3PdCRC(O)R′,7,8 at-
tempts to prepare divalent nickel complexes from the
reactions of 2 with Ni(COD)2 in the presence of a number
of phosphines such as PPh3 or PMe3 led to the formation of
(63) Marinetti, A.; Mathey, F. Organometallics 1984, 3, 456-461.
(64) Watson, W. H.; Wu, G.; Richmond, M. G. Organometallics 2006,
25, 930-945.
Inorganic Chemistry, Vol. 47, No. 2, 2008 753

Lee and Liang
and the amido nitrogen donor in 3a-c are thus mutually
cis. The Namide-Ni-P binding angles of ca. 85° are similar
to those of the nickel derivatives featuring a five-membered
metallacycle such as [iPr-NP]NiCl(PMe3) (85.21(9)°),51 [i-
Pr-NP]NiMe(PMe3) (85.0(1)°),51 [iPr-NP]NiPh(PMe3) (85.9-
(2)°),51 [(o-Ph2PC6H4NHMe)NiCl(PMe3)]PF6 (87.0(1)°),65
and [Ph2PCHdC(Ph)O]Ni(Ph)(PPh3) (86.5°).7 The Ni-
Namide, Ni-P, and Ni-Ph distances of 4a-c are also
comparable to the corresponding values found for nickel(II)
complexes of [iPr-NP]-.51 In 4a-c, the coordination
plane coincides virtually with the backbone N-Csp2-Csp2-P
plane with small dihedral angles of 3.0° (4a), 2.5° (4b), and
7.6° (4c). The N-aryl ring of 4b is approximately perpen-
dicular to the coordination plane (dihedral angle 93.1°),
whereas those of 4a and 4c are tilted severely (dihedral angle
77.1° and 65.9°, respectively) from the ideal orthogonal
geometry. As a result, the pyridine and phenyl ligands are
also tilted accordingly with respect to the coordination plane
in order to minimize the steric repulsion between these
ligands.
Table 1. Crystallographic Data for 1a, 1b, 1d, 2a, 2c, 3d, 4a, 4b, and 4c
{[(2,6-iPr2C6H3)NHC(Me)d
CHPPh3]+Br-}(CH2Cl2)(H2O)
{[(2,6-Me2C6H3)NHC(Me)d
CHPPh3]+Br-}(CH2Cl2)
(1b)
[iBuNHC(Me)d
CHPPh3]+Br-
(1d)
compd
(1a)
formula
fw
D
C34H41BrCl2NOP
661.492
1.292
C30H31BrCl2NP
587.34
1.324
(C25H29BrNP)2(H2O)
926.76
1.265
calc (g cm-3
)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
Triclinic
P1h
monoclinic
C2/c
21.3127(4)
10.0835(3)
16.2680(3)
90
122.569(2)
90
2946.3(1)
4
orthorhombic
Pbca
19.127(4)
13.562(3)
37.528(7)
90
90
90
9735(3)
8
9.8565(3)
11.3286(3)
15.5802(5)
79.602(1)
83.649(1)
88.124(2)
1700.47(9)
2
T (K)
298
293(2)
293(2)
diffractometer
radiation, λ (Å)
2θmax (deg)
total reflns
Kappa CCD
Mo KR, 0.71073
50.10
Kappa CCD
Mo KR, 0.71073
50.06
SMART CCD
Mo KR, 0.71073
52.14
11881
9073
53108
independent reflns
Rint
5940
0.044
1.439
4345
0.0375
1.650
9585
0.0721
1.767
abs coeff (mm-1
)
data/restraints/params
GOF
5940/0/361
2.232
4345/2/316
1.118
9585/0/522
0.872
final R indices [I > 2σ(I)]
R1 ) 0.1146
wR2 ) 0.3181
R1 ) 0.1519
wR2 ) 0.3463
R1 ) 0.0380
wR2 ) 0.0962
R1 ) 0.0448
wR2 ) 0.1219
R1 ) 0.0526
wR2 ) 0.1438
R1 ) 0.1220
wR2 ) 0.1676
R indices (all data)
[(2,6-iPr2C6H3)NdC(Me)CHdPPh3]
(2a)
PhNdC(Me)CHdPPh3
(2c)
[iBuNHC(Me)dCHP(O)Ph2]2(C6H6)
(3d)
compd
formula
fw
D
C33H36NP
477.632
1.143
C27H24NP
393.44
1.218
C44H54N2O2P2
704.876
1.169
calc (g cm-3
)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
monoclinic
P21/c
9.7036(6)
15.480(1)
18.628(1)
90
97.413(2)
90
2774.8(3)
4
monoclinic
P21/c
14.7550(3)
17.6120(4)
17.5880(4)
90
110.168(1)
90
4290.3(2)
8
monoclinic
P21/c
11.3747(3)
16.4104(4)
21.9760(7)
90
102.379(1)
90
4006.7(2)
4
T (K)
298
100(2)
298
diffractometer
radiation, λ (Å)
2θmax (deg)
total reflns
Kappa CCD
Mo KR, 0.71073
50.10
Kappa CCD
Mo KR, 0.71073
50.08
Kappa CCD
Mo KR, 0.71073
50.12
13889
28392
33766
independent reflns
Rint
4849
0.0682
0.120
7575
0.0923
0.141
7078
0.075
0.146
abs coeff (mm-1
)
data/restraints/params
GOF
4849/0/316
1.008
7575/0/523
1.070
7078/0/451
1.177
final R indices [I > 2σ(I)]
R1 ) 0.0598
wR2 ) 0.1481
R1 ) 0.1223
wR2 ) 0.1849
R1 ) 0.0580
wR2 ) 0.1415
R1 ) 0.0989
wR2 ) 0.1693
R1 ) 0.0673
wR2 ) 0.1597
R1 ) 0.1298
wR2 ) 0.2143
R indices (all data)
754 Inorganic Chemistry, Vol. 47, No. 2, 2008

r-Iminophosphorus Ylides and the Ni(II) Complexes
Table 1. Continued
[(iPr2C6H3)NC(Me)dCHPPh2]NiPh(py)
(4a)
[Me2C6H3)NC(Me)dCHPPh2]NiPh(py)
(4b)
[PhNC(Me)dCHPPh2]NiPh(py)
(4c)
compd
formula
fw
D
C38H41N2NiP
615.41
1.266
C34H33N2NiP
576.35
1.281
C32H29N2NiP
531.25
1.321
calc (g cm-3
)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
triclinic
P1h
monoclinic
P21/c
9.1790(2)
14.1900(3)
23.1820(6)
90
98.271(1)
90
2988.1(1)
4
monoclinic
P21/n
10.2380(4)
9.7480(5)
26.779(1)
90
91.737(2)
90
2671.3(2)
4
9.5170(2)
12.1780(2)
15.0260(4)
70.647(1)
84.281(1)
79.506(1)
1614.15(6)
2
T (K)
200(2)
200(2)
200(2)
diffractometer
radiation, λ (Å)
2θmax (deg)
total reflns
Kappa CCD
Mo KR, 0.71073
50.00
Kappa CCD
Mo KR, 0.71073
50.00
Kappa CCD
Mo KR, 0.71073
50.06
21802
20834
13566
independent reflns
Rint
5646
0.0925
0.679
5250
0.0924
0.729
4291
0.0828
0.809
abs coeff (mm-1
)
data/restraints/params
GOF
5646/0/380
1.070
5250/0/344
1.144
4291/0/325
1.057
final R indices [I > 2σ(I)]
R1 ) 0.0554
wR2 ) 0.1196
R1 ) 0.0962
wR2 ) 0.1450
R1 ) 0.0690
wR2 ) 0.1481
R1 ) 0.1270
wR2 ) 0.1960
R1 ) 0.0617
wR2 ) 0.1372
R1 ) 0.1099
wR2 ) 0.1619
R indices (all data)
δ 128.39 for C6D6, and δ 77.23 for CDCl3. The assignment of the
carbon atoms is based on the DEPT 13C NMR spectroscopy. 31P
NMR spectra are referenced externally using 85% H3PO4 at δ 0.
Routine coupling constants are not listed. All NMR spectra were
recorded at room temperature in specified solvents unless otherwise
noted. Elemental analysis was performed on a Heraeus CHN-O
Rapid analyzer.
Materials. Compound prop-2-ynyltriphenylphosphonium bro-
mide56,57 was prepared according to the literature procedures. All
other chemicals were obtained from commercial vendors and used
as received.
X-ray Crystallography. Table 1 summarizes the crystallographic
data for 1a, 1b, 1d, 2a, 2c, 3d, 4a, 4b, and 4c. Data were collected
on a Bruker-Nonius Kappa CCD diffractometer or a SMART CCD
diffractometer with graphite-monochromated Mo KR radiation (λ
) 0.7107 Å). Structures were solved by direct methods and refined
by full-matrix least-squares procedures against F2 using WinGX
crystallographic software package or SHELXL-97. All full-weight
non-hydrogen atoms were refined anisotropically. Hydrogen atoms
were placed in calculated positions.
Conclusions
In summary, we have prepared and characterized a series
of N-arylated and N-alkylated R-iminophosphorus ylides
2a-d and studied the reactivity of these molecules with Ni-
(COD)2. Interestingly, a strong 1,4-intramolecular, nonco-
valent interaction is found for these R-iminophosphorus
ylides as evidenced by solution NMR spectroscopic and
solid-state X-ray crystallographic studies. Unexpectedly, the
N-tert-butyl-derived 2d reacts with water to generate an ene-
amine-functionalized phosphine oxide 3d, a transformation
that presumably involves concomitant bond cleavage of
P-Ph and O-H and bond formation of N-H, PdO, and
Ph-H. The P-Ph bond activation mediated by water under
extremely mild conditions is intriguing.63,64 Upon reactions
with Ni(COD)2 in the presence of pyridine, the N-arylated
R-iminophosphorus ylides 2a-c are transformed to bidentate
amido phosphine ligands in which the two donor atoms are
connected by an olefinic backbone. The nickel-bound phenyl
group in 4a-c is cis to the phosphorus donor as verified by
X-ray crystallography.
Synthesis of 2-(2,6-Diisopropylanilino)-prop-1-enyltriphe-
nylphosphonium Bromide (1a). A solution of 2,6-dimethylaniline
(505 mg, 2.62 mmol) in acetonitrile (10 mL) was added via a
syringe to a Schlenk flask containing solid prop-2-ynyltriph-
enylphosphonium bromide (1.0 g, 2.62 mmol) under nitrogen. The
reaction solution was stirred and heated to reflux overnight. After
being cooled to room temperature, the solution was evaporated to
dryness under reduced pressure. The solid thus obtained was
dissolved in a minimal amount of CH2Cl2 (15 mL), and ethyl acetate
(10 mL) was added. The solution was stirred at room temperature
for 30 min, resulting in the formation of white precipitate, which
was collected on a frit by filtration and dried in vacuo; yield 1.26
g (86%). Colorless crystals suitable for X-ray diffraction analysis
were grown from a concentrated CH2Cl2 solution at room temper-
Experimental Section
General Procedures. Unless otherwise specified, all experiments
were performed under nitrogen using standard Schlenk or glovebox
techniques. All solvents were reagent grade or better and purified
by standard methods. The NMR spectra were recorded on Varian
Unity or Bruker AV instruments. Chemical shifts (δ) are listed as
parts per million downfield from tetramethylsilane, and coupling
1
constants (J) are in hertz. H NMR spectra are referenced using
the residual solvent peak at δ 7.16 for C6D6 and δ 7.27 for CDCl3.
13C NMR spectra are referenced using the residual solvent peak at
1
ature; yield 1.16 g (79%). H NMR (CDCl3, 500 MHz) δ 10.16
(65) Crociani, L.; Tisato, F.; Refosco, F.; Bandoli, G.; Corain, B. Eur. J.
Inorg. Chem. 1998, 1689-1697.
(br d, 1, JHP ) 4 Hz, NH), 7.69 (t, 3, Ar), 7.57 (m, 6, Ar), 7.45 (m,
Inorganic Chemistry, Vol. 47, No. 2, 2008 755

Lee and Liang
2
6, Ar), 7.25 (t, 1, Ar), 7.15 (d, 2, Ar), 3.41 (d, 1, JHP ) 16 Hz,
minimal amount of CH2Cl2 (10 mL), and ethyl acetate (15 mL)
was added. The solution was stirred at room temperature for 30
min, resulting in the formation of orange precipitate, which was
collected on a frit by filtration and dried in vacuo; yield 1.02 g
(86%). Orange crystals suitable for X-ray diffraction analysis were
grown from a concentrated CH2Cl2/Et2O solution at room temper-
ature; yield 0.95 g (80%). 1H NMR (CDCl3, 500 MHz) δ 7.94 (br
d, 1, JHP ) 4.0 Hz, NH), 7.67 (t, 3, Ar), 7.57 (m, 9, Ar), 7.53 (t,
MeCdCH), 3.24 (septet, 2, CHMe2), 2.16 (s, 3, MeCdCH), 1.25
(d, 6, JHH ) 7 Hz, CHMe2), 1.16 (d, 6, JHH ) 7 Hz, CHMe2). 31P-
{1H} NMR (CDCl3, 202.31 MHz) δ 17.10. 13C{1H} NMR (CDCl3,
125.5 MHz) δ 167.63 (d, 2JCP ) 15.44 Hz, MeCdCH), 146.40 (s,
4
ortho-NAr), 133.90 (d, JCP ) 2.76 Hz, para-PC6H5), 132.62 (d,
3JCP ) 9.92 Hz, meta-PC6H5), 129.95 (d, JCP ) 12.68 Hz, ortho-
2
PC6H5), 128.63 (s, para-NAr), 123.94 (s, meta-NAr), 123.34 (d,
1JCP ) 91.62, ipso-PC6H5), 56.62 (d, JCP ) 121.36 Hz, MeCd
CH), 28.56 (s, CHMe2), 24.73 (s, CHMe2), 23.81 (s, CHMe2), 21.66
(d, JCP ) 5.40 Hz, MeCdCH). Anal. Calcd for C33H37BrNP: C,
1
2
3, Ar), 3.85 (d, 1, JHP ) 15.5 Hz, MeCdCH), 1.92 (s, 3, MeCd
CH), 1.47 (s, 9, CMe3). 31P{1H} NMR (CDCl3, 202.31 MHz) δ
3
2
16.27. 13C{1H} NMR (CDCl3, 125.5 MHz) δ 164.15 (d, JCP
)
4
70.96; H, 6.68; N, 2.51. Found: C, 70.63; H, 6.68; N, 2.57.
Synthesis of 2-(2,6-Dimethylanilino)-prop-1-enyltriphenylphos-
phonium Bromide (1b). A solution of 2,6-dimethylaniline (318
mg, 2.62 mmol) in acetonitrile (10 mL) was added via a syringe to
a Schlenk flask containing solid prop-2-ynyltriphenylphosphonium
bromide (1.0 g, 2.62 mmol) under nitrogen. The reaction solution
was stirred and heated to reflux overnight. After being cooled to
room temperature, the solution was evaporated to dryness under
reduced pressure. The solid thus obtained was dissolved in a
minimal amount of CH2Cl2 (10 mL), and ethyl acetate (15 mL)
was added. The solution was stirred at room temperature for 30
min, resulting in the formation of white precipitate, which was
collected on a frit by filtration and dried in vacuo; yield 1.087 g
(83%). Colorless crystals suitable for X-ray diffraction analysis were
grown by slow evaporation of a concentrated CH2Cl2 solution at
12.55 Hz, MeCdCH), 133.72 (d, JCP ) 2.64 Hz, para-PC6H5),
132.65 (d, 2JCP ) 10.67 Hz, meta-PC6H5), 129.89 (d, 3JCP ) 12.43
Hz, ortho-PC6H5), 123.66 (d, 1JCP ) 91.11 Hz, ipso-PC6H5), 56.23
(d, 1JCP ) 121.48 Hz, MeC)CH), 52.98 (s, CMe3), 28.51 (s, CMe3),
3
24.21 (d, JCP ) 6.15 Hz, MeCdCH). Anal. Calcd for (C25H29-
BrNP)4(H2O): C, 65.41; H, 6.48; N, 3.05. Found: C, 65.33; H,
6.43; N, 2.95. Incorporation of water is confirmed by X-ray
crystallography. Complete removal of the water molecules from
recrystallized samples was not successful.
Deprotonation of 2-(2,6-Diisopropylanilino)-prop-1-enyltriph-
enylphosphonium Bromide (1a): Synthesis of 2a. Solid NaH (50
mg, 2.08 mmol, 3.9 equiv) was added to a solution of 2-(2,6-
diisopropylanilino)-prop-1-enyltriphenylphosphonium bromide (300.4
mg, 0.538 mmol) dissolved in THF (15 mL) at -35 °C. After being
stirred at room temperature overnight, the reaction mixture was
filtered through a pad of Celite to remove the excess amount of
NaH, which was further washed with THF (5 mL) until the
washings became colorless. The filtrate and washings were
combined, and THF was removed in vacuo. The pale yellow solid
residue was extracted with benzene (10 mL). The benzene solution
was filtered through a pad of Celite and evaporated to dryness under
reduced pressure, affording the product as a pale yellow solid; yield
215 mg (84%). Yellow crystals suitable for X-ray diffraction
analysis were grown from a concentrated THF/benzene solution at
1
room temperature; yield 1.054 g (80%). H NMR (CDCl3, 500
MHz) δ 10.26 (br d, 1, JHP ) 4.0 Hz, NH), 7.70 (t, 3, Ar), 7.59
(m, 6, Ar), 7.50 (m, 6, Ar), 7.08 (m, 3, Ar), 3.47 (d, 1, 2JPH ) 16.5
Hz, MeCdCH), 2.39 (s, 6, ArCH3), 2.20 (s, 3, MeCdCH). 31P-
{1H} NMR (CDCl3, 202.31 MHz) δ 17.23. 13C{1H} NMR (CDCl3,
125.5 MHz) δ 166.27 (d, 2JCP ) 15.44 Hz, MeCdCH), 135.96 (s,
ortho-NAr), 135.23 (s, ipso-NAr), 133.89 (s, para-PC6H5), 132.76
3
2
(d, JCP ) 9.92, meta-PC6H5), 129.99 (d, JCP ) 12.68, ortho-
PC6H5), 128.51 (s, meta-NAr), 127.80 (s, para-NAr), 123.61 (d,
1JCP ) 91.62, ipso-PC6H5), 55.24 (d, JCP ) 122.36 Hz, MeCd
1
1
room temperature. H NMR (C6D6, 500 MHz) δ 7.76 (dd, 6, Ar),
CH), 21.86 (d, 3JCP ) 4.52 Hz, MeCdCH), 18.61 (s, ArMe). Anal.
Calcd for C29H29BrNP: C, 69.33; H, 5.82; N, 2.79. Found: C,
69.02; H, 5.84; N, 2.74.
7.17 (d, 2, Ar), 6.98-7.09 (m, 10, Ar), 3.05 (d, 1, 2JHP ) 25.5 Hz,
HCdPPh3), 2.92 (septet, 2, 3JHH ) 7 Hz, CHMe2), 1.92 (d, 3, 4JPH
) 2.0 Hz, MeCdNAr), 1.20 (d, 6, 3JHH ) 7 Hz, CHMe2), 0.98 (d,
3
6, JHH ) 7 Hz, CHMe2). 31P{1H} NMR (C6D6, 202.31 MHz) δ
Synthesis of 2-Anilinoprop-1-enyltriphenylphosphonium Bro-
mide (1c). A solution of aniline (244 mg, 2.62 mmol) in acetonitrile
(10 mL) was added via a syringe to a Schlenk flask containing
solid prop-2-ynyltriphenylphosphonium bromide (1.0 g, 2.62 mmol)
under nitrogen. The reaction solution was stirred and heated to
reflux overnight. After being cooled to room temperature, the
solution was evaporated to dryness under reduced pressure. The
solid thus obtained was dissolved in a minimal amount of CH2Cl2
(8 mL), and ethyl acetate (15 mL) was added. The solution was
stirred at room temperature for 30 min, resulting in the formation
of white precipitate, which was collected on a frit by filtration and
dried in vacuo; yield 560 mg (90%). 1H NMR (CDCl3, 200 MHz)
δ 10.36 (br s, 1, NH), 7.02-7.36 (m, 15, Ar), 6.77-6.98 (m, 5,
Ar), 4.38 (d, 1, CH), 1.23 (s, 3, CH3). 31P{1H} NMR (CDCl3, 80.95
MHz) δ 17.32. The NMR spectroscopic data are identical to those
reported previously.56
13.50. 13C{1H} NMR (C6D6, 125.5 MHz) δ 166.39 (d, 2JCP ) 3.64
Hz, MeCdNAr), 150.89 (s, C), 140.37 (s, C), 133.95 (d, JCP
10.04 Hz, CH), 131.75 (d, JCP ) 2.76 Hz, CH), 130.58 (d, 1JCP
)
)
88.98 Hz, ipso-PC6H5), 128.92 (d, JCH ) 11.80 Hz, CH), 123.28
1
(s, CH), 121.99 (s, CH), 40.54 (d, JCP ) 115.34 Hz, HCdPPh3),
28.23 (s, CHMe2), 24.87 (s, CHMe2), 24.47 (s, CHMe2), 22.13 (d,
3JCP ) 16.32 Hz, MeCdNAr). Anal. Calcd for C33H36NP: C, 82.99;
H, 7.60; N, 2.93. Found: C, 83.00; H, 7.57; N, 2.89.
Deprotonation of 2-(2,6-Dimethylanilino)-prop-1-enyltriph-
enylphosphonium Bromide (1b): Synthesis of 2b. Solid NaH
(108 mg, 4.51 mmol, 7.4 equiv) was added to a solution of 2-(2,6-
dimethylanilino)-prop-1-enyltriphenylphosphonium bromide (307.6
mg, 0.61 mmol) dissolved in THF (15 mL) at -35 °C. After being
stirred at room temperature for 4 h, the reaction mixture was filtered
through a pad of Celite to remove the excess amount of NaH, which
was further washed with THF (4 mL) until the washings became
colorless. The filtrate and washings were combined, and THF was
removed in vacuo. The pale yellow solid residue was extracted with
benzene (10 mL). The benzene solution was filtered through a pad
of Celite and evaporated to dryness under reduced pressure,
affording the product as a pale yellow solid; yield 235 mg (91%).
Yellow crystals suitable for X-ray diffraction analysis were grown
from a concentrated THF/benzene solution at room temperature.
Synthesis of 2-(tert-Butylamino)-prop-1-enyltriphenylphos-
phonium Bromide (1d). A solution of tert-butylamine (0.28 mL,
2.62 mmol) in acetonitrile (10 mL) was added via a syringe to a
Schlenk flask containing solid prop-2-ynyltriphenylphosphonium
bromide (1.0 g, 2.62 mmol) under nitrogen. The reaction solution
was stirred and heated to reflux overnight. After being cooled to
room temperature, the solution was evaporated to dryness under
reduced pressure. The solid thus obtained was dissolved in a
756 Inorganic Chemistry, Vol. 47, No. 2, 2008

r-Iminophosphorus Ylides and the Ni(II) Complexes
1H NMR (C6D6, 500 MHz) δ 7.81 (dd, 6, Ar), 7.10 (d, 2, Ar), 7.06
led to colorless cubes of 3d suitable for X-ray diffraction analysis.
Alternatively, hydrolysis of 2d in THF at room temperature also
afforded 3d on the basis of NMR studies. H NMR (C6D6, 500
2
(d, 2, Ar), 7.00 (m, 7, Ar), 6.89 (t, 1, Ar), 3.11 (d, 1, JHP ) 26.5
4
1
Hz, HCdPPh3), 1.96 (s, 6, ArCH3), 1.88 (d, 3, JHP ) 1.5 Hz,
MeCdNAr). 31P{1H} NMR (C6D6, 202.31 MHz) δ 13.75. 13C{1H}
MHz) δ 8.06 (m, 4, Ar), 7.09 (m, 6, Ar), 5.37 (br s, 1, NH), 4.66
2
2
NMR (C6D6, 125.5 MHz) δ 165.36 (d, JCP ) 4.02 Hz, MeCd
(d, 1, JHP ) 19, MeCdCH), 2.18 (s, 3, MeCdCH), 1.17 (s, 9,
NAr), 153.85 (s, C), 134.08 (d, Jcp ) 10.04 Hz, CH), 131.67 (d,
CMe3). 31P{1H} NMR (C6D6, 202.31 MHz) δ 21.39. 13C{1H} NMR
(C6D6, 125.5 MHz) δ 158.10 (d, 2JCP ) 19.8 Hz, MeCdCH), 140.06
1
Jcp ) 2.76 Hz, CH), 130.10 (d, Jcp ) 89.98 Hz, ipso-PC6H5),
1
129.84 (s, C), 128.78 (d, Jcp ) 11.80 Hz, CH), 128.30 (s, CH),
120.95 (s, CH), 39.64 (d, 1Jcp ) 116.21 Hz, HCdPPh3), 21.70 (d,
3Jcp ) 16.82 Hz, MeCdNAr), 19.52 (s, ArMe). Anal. Calcd for
C29H28NP: C, 82.63; H, 6.70; N, 3.32. Found: C, 82.39; H, 6.73;
N, 3.26.
(d, JCP ) 104.4 Hz, ipso-PC6H5), 131.73 (d, JCP ) 9.0 Hz, CH),
130.85 (d, JCP ) 29.1 Hz, CH), 128.88 (d, JCP ) 10.8 Hz, CH),
81.18 (d, 1JCP ) 128.5 Hz, MeCdCH), 51.32 (s, CMe3), 29.00 (s,
CMe3), 22.41 (d, JCP ) 7.3 Hz, MeCdCH).
Synthesis of 4a. To a solid mixture of 2a (320 mg, 0.67 mmol)
and Ni(COD)2 (203 mg, 0.74 mmol, 1.1 equiv) was added toluene
(10 mL) at room temperature. The reaction mixture was stirred at
room temperature for 10 min to allow for the complete dissolution
of the starting materials. Pyridine (848 mg, 11 mmol, 16 equiv)
was added. The reaction solution was heated to 50 °C for 10 min
and then stirred at room temperature for 1 day. After being filtered
through a pad of Celite to remove a black insoluble solid, the
toluene solution was concentrated under reduced pressure until a
red, microcrystalline solid began to deposit. The concentrated
toluene solution was cooled to -35 °C to afford the product as red
crystals, which were isolated, washed with pentane (1 mL × 3),
and dried in vacuo; yield 150 mg (36%). The red crystals thus
obtained were suitable for X-ray diffraction analysis. 1H NMR
(C6D6, 500 MHz) δ 8.22 (d, 2, Ar), 7.83 (t, 4, Ar), 7.43 (d, 2, Ar),
7.17 (m, 6, Ar), 6.95 (m, 1, Ar), 6.90 (m, 2, Ar), 6.76 (m, 2, Ar),
6.70 (m, 1, Ar), 6.33 (t, 1, Ar), 6.03 (t, 2, Ar), 3.86 (septet, 2, 3JHH
) 6.5 Hz, CHMe2), 3.84 (d, 1, 2JHP ) 1.5 Hz, MeCdCH), 1.85 (s,
3, MeCdCH), 1.28 (d, 6, 3JHH ) 6.5 Hz, CHMe2), 1.22 (d, 6, 3JHH
) 6.5 Hz, CHMe2). 31P{1H} NMR (C6D6, 202.31 MHz) δ 31.22.
Deprotonation of 2-Anilinoprop-1-enyltriphenylphosphonium
Bromide (1c): Synthesis of 2c. Solid NaH (12 mg, 0.5 mmol,
1.58 equiv) was added to a solution of 2-anilinoprop-1-enyltriph-
enylphosphonium bromide (150 mg, 0.316 mmol) dissolved in THF
(10 mL) at -35 °C. After being stirred at room temperature for 4
h, the reaction mixture was filtered through a pad of Celite to
remove the excess amount of NaH, which was further washed with
THF (2 mL) until the washings became colorless. The filtrate and
washings were combined, and THF was removed in vacuo. The
pale yellow solid residue was extracted with benzene (10 mL). The
benzene solution was filtered through a pad of Celite and evaporated
to dryness under reduced pressure, affording the product as a pale
yellow solid; yield 66 mg (53%). Yellow crystals suitable for X-ray
diffraction analysis were grown from a concentrated THF/benzene
1
solution at room temperature. H NMR (C6D6, 500 MHz) δ 7.79
(dd, 6, Ar), 7.20 (t, 2, Ar), 7.02 (m, 9, Ar), 6.87 (t, 1, Ar), 6.75 (d,
2
4
2, Ar), 3.12 (d, 1, JHP ) 28.5 Hz, HCdPPh3), 2.13 (d, 3, JHP
)
2.5 Hz, MeCdNAr). 31P{1H} NMR (C6D6, 202.31 MHz) δ 14.01.
13C{1H} NMR (C6D6, 125.5 MHz) δ 166.00 (s, MeCdNPh), 155.33
(s, C), 133.89 (d, JCP ) 9.41 Hz, CH), 131.58 (s, CH), 130.09 (d,
JCP ) 90.74 Hz, ipso-PC6H5), 129.01 (s, CH), 128.84 (s, CH),
123.23 (s, CH), 120.56 (s, CH), 43.06 (d, 1JCP ) 115.34 Hz, HCd
2
13C{1H} NMR (C6D6, 125.5 MHz) δ 175.73 (d, JCP ) 22.0 Hz,
2
HCdCMe), 157.61 (d, JCP ) 43.9 Hz, NiC), 150.58 (s, CH),
148.92 (s, C), 145.84 (s, C), 138.35 (s, CH), 136.10 (d, JCP ) 53.1
Hz, C), 135.48 (s, CH), 133.60 (s, CH), 133.52 (s, CH), 129.57 (s,
CH), 126.26 (s, CH), 124.37 (s, CH), 123.42 (s, CH), 123.36 (s,
CH), 122.34 (s, CH), 72.02 (d, 1JCP ) 55.0 Hz, HCdCMe), 28.61
3
PPh3), 20.49 (d, JCP ) 16.06 Hz, MeCdNPh). LRMS (EI) calcd
for C27H24NP m/z 393, found m/z 393. Anal. Calcd for (C27H24-
NP)3(C4H8O): C, 81.50; H, 6.44; N, 3.36. Found: C, 81.36; H,
6.11; N, 3.02.
(s, CHMe2), 24.92 (s, CHMe2), 24.35 (s, CHMe2), 21.39 (d, 3JCP
)
18.3 Hz, HCdCMe). Anal. Calcd for C38H41N2NiP: C, 74.16; H,
6.72; N, 4.55. Found: C, 74.15; H, 6.69; N, 4.47.
Deprotonation of 2-(tert-Butylamino)-prop-1-enyltriphe-
nylphosphonium Bromide (1d): Synthesis of 2d. Solid NaH (43
mg, 1.69 mmol, 4.0 equiv) was added to a solution of 2-(tert-
butylamino)-prop-1-enyltriphenylphosphonium bromide (191.8 mg,
0.422 mmol) dissolved in THF (10 mL) at -35 °C. After being
stirred at room temperature for 4 h, the reaction mixture was filtered
through a pad of Celite to remove the excess amount of NaH, which
was further washed with THF (2 mL) until the washings became
colorless. The filtrate and washings were combined, and THF was
removed in vacuo. The orange, oily residue was extracted with
benzene (10 mL). The benzene solution was filtered through a pad
of Celite and evaporated to dryness under reduced pressure,
affording the product as reddish orange viscous oil; yield 142 mg
Synthesis of 4b. To a solid mixture of 2b (160 mg, 0.38 mmol)
and Ni(COD)2 (115 mg, 0.42 mmol, 1.1 equiv) was added toluene
(6 mL) at room temperature. The reaction mixture was stirred at
room temperature for 5 min to allow for the complete dissolution
of the starting materials. Pyridine (480 mg, 6.08 mmol, 16 equiv)
was added. The reaction solution was heated to 50 °C for 10 min
and then stirred at room temperature for 1 day. After being filtered
through a pad of Celite to remove a black insoluble solid, the
toluene solution was evaporated to dryness under reduced pressure.
The solid residue was dissolved in diethyl ether (10 mL). The ether
solution was filtered through a pad of Celite and concentrated in
vacuo to give a red solution which contained yellow crystals of
Ni(COD)2. The red diethyl ether solution was separated from the
yellow crystals and evaporated to dryness under reduced pressure
to give the product as a red crystalline solid. In some cases, repeated
extraction of the product with diethyl ether was necessary to ensure
the complete removal of Ni(COD)2. Alternatively, yellow crystals
of Ni(COD)2 might be manually separated with capillaries from
the red crystals of 4b after complete evaporation of the diethyl ether
solutions. Yield 70 mg (33%). Crystals suitable for X-ray diffraction
analysis were grown from a concentrated diethyl ether solution at
-35 °C. 1H NMR (C6D6, 500 MHz) δ 8.21 (d, 2, Ar), 7.85 (dd, 4,
Ar), 7.48 (d, 2, Ar), 7.19 (m, 6, Ar), 6.81 (t, 2, Ar), 6.74 (t, 1, Ar),
1
(90%). H NMR (C6D6, 500 MHz) δ 7.80 (dd, 6, Ar), 7.03-7.09
(m, 9, Ar), 2.79 (d, 1, 2JHP ) 31.5 Hz, HCdPPh3), 2.14 (d, 3, 4JHP
) 3.0 Hz, MeCdNCMe3), 1.14 (s, 9, CMe3). 31P{1H} NMR (C6D6,
202.31 MHz) δ 11.64. 13C{1H} NMR (C6D6, 125.5 MHz) δ 164.25
2
(d, JCP ) 2.76 Hz, MeCdNCMe3), 133.82 (d, JCP ) 9.54 Hz,
1
CH), 132.03 (d, JCP ) 90.36 Hz, ipso-PC6H5), 131.00 (d, JCP
)
2.76 Hz, CH), 128.48 (d, JCP ) 11.80 Hz, CH), 54.00 (s, CMe3),
1
41.18 (d, JCP ) 120.36 Hz, HCdPPh3), 32.34 (s, CMe3), 21.79
(d, 3JCP ) 16.32 Hz, MeCdNCMe3). HRMS (EI) calcd for C25H28-
NP m/z 373.1959, found m/z 373.1956.
Synthesis of 3d. Attempts to crystallize the oily 2d from a
concentrated diethyl ether/benzene solution at room temperature
Inorganic Chemistry, Vol. 47, No. 2, 2008 757

Lee and Liang
6.66 (m, 2, Ar), 6.60 (m, 1, Ar), 6.32 (t, 1, Ar), 5.94 (t, 2, Ar),
3.82 (d, 1, 2JHP ) 2.5 Hz, HCdCMe), 2.40 (s, 6, ArCH3), 1.70 (s,
3, HCdCMe). 31P{1H} NMR (C6D6, 202.31 MHz) δ 32.09. 13C-
{1H} NMR (C6D6, 125.5 MHz) δ 174.60 (d, 2JCP ) 23.8 Hz, HCd
6.76 (d, 1, Ar), 6.73 (m, 2, Ar), 6.68 (d, 2, Ar), 6.59 (t, 1, Ar),
6.30 (t, 1, Ar), 5.94 (t, 2, Ar), 3.87 (d, 1, 2JHP ) 1 Hz, HCdCMe),
1.98 (s, 3, HCdCMe). 31P{1H} NMR (C6D6, 202.31 MHz) δ 31.32.
2
13C{1H} NMR (C6D6, 125.5 MHz) δ 174.39 (d, JCP ) 23.7 Hz,
2
CMe), 157.68 (d, JCP ) 41.7 Hz, NiC), 151.06 (s, C), 149.49 (s,
HCdCMe), 157.40 (d, 2JCP ) 42.04 Hz, NiC), 153.87 (s, C), 150.39
(s, CH), 138.36 (d, JCP ) 1.9 Hz, CH), 135.72 (d, JCP ) 53.1 Hz,
C), 135.24 (s, CH), 133.64 (d, JCP ) 10.0 Hz, CH), 129.67 (d, JCP
) 1.9 Hz, CH), 129.22 (s, CH), 128.69 (s, CH), 127.98 (s, CH),
126.34 (d, JCP ) 1.9 Hz, CH), 123.73 (s, CH), 122.43 (s, CH),
CH), 138.00 (d, JCP ) 1.9 Hz, CH), 136.01 (d, JCP ) 53.5 Hz, C),
135.46 (s, CH), 135.37 (s, C), 133.57 (d, JCP ) 10.2 Hz, CH),
129.58 (d, JCP ) 2.8 Hz, CH), 128.78 (d, JCP ) 11.9 Hz, CH),
127.77 (s, CH), 126.23 (d, JCP ) 1.8 Hz, CH), 123.28 (s, CH),
123.27 (s, CH), 122.35 (s, CH), 71.53 (d, 1JCP ) 56.2 Hz, MeCd
CH), 20.71 (d, 3JCP ) 17.3 Hz, HCdCMe), 19.85 (s, ArCH3). Anal.
Calcd for C34H33N2NiP: C, 73.01; H, 5.95; N, 5.01. Found: C,
72.98; H, 6.16; N, 4.86.
1
121.90 (s, CH), 73.50 (d, JCP ) 54.8 Hz, HCdCMe), 21.66 (d,
3JCP ) 16.4 Hz, HCdCMe). Anal. Calcd for C32H29N2NiP: C,
72.35; H, 5.50; N, 5.27. Found: C, 72.47; H, 5.56; N, 5.20.
Acknowledgment. We thank the National Science Coun-
cil of Taiwan for financial support (NSC 96-2628-M-110-
007-MY3) of this work, Professor Hon Man Lee (National
Changhua University of Education) and Mr. Ting-Shen Kuo
(National Taiwan Normal University) for assistance with
X-ray crystallography, and the National Center for High-
performance Computing (NCHC) for computer time and
facilities. We also thank the reviewers for insightful com-
ments.
Synthesis of 4c. To a solid mixture of 2c (199 mg, 0.51 mmol)
and Ni(COD)2 (153 mg, 0.56 mmol, 1.1 equiv) was added toluene
(8 mL) at room temperature. The reaction mixture was stirred at
room temperature for 5 min to allow for the complete dissolution
of the starting materials. Pyridine (640 mg, 8.1 mmol, 16 equiv)
was added. The reaction solution was heated to 50 °C for 10 min
and then stirred at room temperature for 1 day. After being filtered
through a pad of Celite to remove a black insoluble solid, the
toluene solution was evaporated to dryness under reduced pressure.
The solid residue was dissolved in diethyl ether (13 mL). The ether
solution was filtered through a pad of Celite, concentrated in vacuo,
and cooled to -35 °C to give the product as red crystals, which
were isolated, washed with pentane, and dried in vacuo, yield 200
mg (74%). The red crystals thus obtained were suitable for X-ray
Supporting Information Available: Fully labeled molecular
structures of 1a, 1b, 1d, 2a, 2c, 3d, 4a, 4b, and 4c with selected
bond distances and angles and X-ray crystallographic data in CIF
format for these compounds. This material is available free of charge
via the Internet at http://pubs.acs.org.
1
diffraction analysis. H NMR (C6D6, 500 MHz) δ 8.18 (d, 2, Ar),
7.82 (m, 4, Ar), 7.49 (d, 2, Ar), 7.18 (m, 6, Ar), 6.83 (t, 2, Ar),
IC701836J
758 Inorganic Chemistry, Vol. 47, No. 2, 2008