Nickel(II) complexes containing bidentate diarylamido phosphine ligands

Article abstract of DOI:10.1021/om0498145

A series of diamagnetic divalent nickel complexes supported by bidentate diarylamido phosphine ligands have been prepared and characterized. Deprotonation of N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline (H[ ⁱPr-NP]) and N-(2-diphenylpho

Full text of DOI:10.1021/om0498145

3538
Organometallics 2004, 23, 3538-3547
Nick el(II) Com p lexes Con ta in in g Bid en ta te Dia r yla m id o
P h osp h in e Liga n d s
Lan-Chang Liang,* Wei-Ying Lee, and Chi-Chun Yin
Department of Chemistry and Center for Nanoscience & Nanotechnology, National Sun
Yat-sen University, Kaohsiung 80424, Taiwan
Received March 15, 2004
A series of diamagnetic divalent nickel complexes supported by bidentate diarylamido
phosphine ligands have been prepared and characterized. Deprotonation of N-(2-diphe-
nylphosphinophenyl)-2,6-diisopropylaniline (H[iPr-NP]) and N-(2-diphenylphosphinophenyl)-
2,6-dimethylaniline (H[Me-NP]) with n-BuLi in THF at -35 °C produced the corresponding
lithium complexes, [iPr-NP]Li(THF)2 and [Me-NP]Li(THF)2, respectively. The chloride
complex {[iPr-NP]NiCl}2 is accessible from the reaction of NiCl2(DME) with [iPr-NP]Li(THF)2
or H[iPr-NP] in the presence of triethylamine. Addition of PMe3 to {[iPr-NP]NiCl}2 afforded
[iPr-NP]NiCl(PMe3), from which [iPr-NP]NiMe(PMe3), [iPr-NP]NiPh(PMe3), and [iPr-NP]-
Ni(η3-CH2Ph) were prepared from the metathetical reactions with appropriate Grignard
reagents. Solution NMR data of [iPr-NP]NiMe(PMe3) revealed two geometric isomers at room
temperature with the major species carrying PMe3 cis to the phosphorus donor of the amido
phosphine ligand. Interestingly, only one of the possible isomers is observed for [iPr-NP]-
NiCl(PMe3) and [iPr-NP]NiPh(PMe3), in which the two phosphorus donors in the former are
exclusively cis whereas those in the latter are trans. The benzyl complexes [iPr-NP]Ni(η3-
CH2Ph) and [Me-NP]Ni(η3-CH2Ph) are prepared directly from the reactions of [iPr-NP]Li-
(THF)2 and [Me-NP]Li(THF)2, respectively, with Ni(COD)2 in the presence of benzyl chloride.
1
The η3-feature of the benzyl ligand maintained in solution is elucidated by the J CH value
observed for the benzylic methylene group in the NMR spectroscopy. In addition to the
spectroscopic data for all new molecules, X-ray structures of H[iPr-NP], [Me-NP]Li(THF)2,
[iPr-NP]NiCl(PMe3), [iPr-NP]NiMe(PMe3), [iPr-NP]NiPh(PMe3), [iPr-NP]Ni(η3-CH2Ph), and
[Me-NP]Ni(η3-CH2Ph) are presented.
In tr od u ction
and [N-N]- (Chart 1).21-27 With careful modification
of the ligand design, the reactivity and stability (or
functional group compatibility) of the nickel catalysts
may be finely tuned. In comparison, nickel chemistry
Divalent nickel complexes supported by monoanionic,
bidentate, four-electron [L-X]- ligands are currently
under extensive investigation, particularly for the de-
velopment of neutral, single-component catalysts for ole-
fin oligomerization, polymerization, and copolymeriza-
tion.1 Recent progress in this aspect highlights mol-
ecules that are reminiscent of catalysts for Shell Higher
Olefin Process (SHOP).2,3 Several classes of ligands
investigated thus far include [O-P]-,4-8 [O-N]-,9-20
(11) Hicks, F. A.; Brookhart, M. Organometallics 2001, 20, 3217-
3219.
(12) Hicks, F. A.; J enkins, J . C.; Brookhart, M. Organometallics
2003, 22, 3533-3545.
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256.
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(16) Zhang, D.; J in, G.-X.; Hu, N. Chem. Commun. 2002, 574-575.
(17) Shim, C. B.; Kim, Y. H.; Lee, B. Y.; Dong, Y.; Yun, H.
Organometallics 2003, 22, 4272-4280.
* Corresponding author. Fax: +886-7-5253908. E-mail: lcliang@
mail.nsysu.edu.tw.
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10.1021/om0498145 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 06/09/2004

Amido Phosphine Complexes of Nickel
Organometallics, Vol. 23, No. 14, 2004 3539
Ch a r t 1. Rep r esen ta tive Exa m p les of Mon oa n ion ic, Bid en ta te, F ou r -Electr on [L-X]- Liga n d s
Ch a r t 2
involving bidentate [N-P]- ligands remains relatively
undeveloped.28-32
We have recently established a synthetic protocol for
the preparation of a series of potentially rigid and robust
amido phosphine ligands that are o-phenylene deriva-
tives (Chart 2).33 Nickel alkyl complexes of a tridentate
bis(2-diphenylphosphinophenyl)amide ([PNP]-) ligand,
F igu r e 1. Molecular structure of H[iPr-NP] with thermal
including those containing â-hydrogen atoms, have
ellipsoids drawn at the 35% probability level. Only one of
shown unusual thermal stability. One intriguing feature
the two independent molecules found in the asymmetric
worthy of note regarding the nickel derivatives of
unit cell is presented for clarity. Selected bond distances
(Å) and angles (deg): N(2)-C(43) 1.3877(19), N(2)-C(39)
1.426(2), P(2)-C(49) 1.829(2), P(2)-C(48) 1.8297(18), P(2)-
[PNP]- is that analogous complexes supported by the
closely related [N(SiMe2CH2PR2)2]- ligands34 are either
synthetically inaccessible or thermally unstable. In
addition, the palladium complexes of [PNP]- are mark-
edly stable at temperatures as high as 200 °C. As a
result, extremely high turnover numbers and frequen-
cies have been achieved for catalytic Heck olefination
of aryl halides.35 In a parallel pursuit, we have set out
to examine group 10 metal complexes of bidentate amido
phosphine ligands, with primary goals directed to
catalytic reactions with olefinic substrates. Utilization
of sterically demanding ligands is attempted to prevent
or diminish the possibility of the formation of bis-ligand
complexes that have proven to be inactive in the SHOP-
type catalytic systems.9,12,36,37 In this contribution, we
aim to demonstrate the synthetic possibility of divalent
C(55) 1.8326(18), C(43)-N(2)-C(39) 124.80(14), C(49)-
P(2)-C(48) 100.90(8), C(49)-P(2)-C(55) 102.69(9), C(48)-
P(2)-C(55) 102.43(8).
nickel complexes incorporating the bidentate diaryla-
mido phosphine ([NP]-) ligands. Spectroscopic data and
molecular structures of these compounds are discussed.
Resu lts a n d Discu ssion
P r ep a r a tion of Lith iu m Der iva tives of th e Am i-
d o P h osp h in e Liga n d s. The ligand precursors
N-(2-diphenylphosphinophenyl)-2,6-diisopropylaniline
(H[iPr-NP]) and N-(2-diphenylphosphinophenyl)-2,6-
dimethylaniline (H[Me-NP]) were prepared following
the procedures reported previously.38,39 During our
synthetic work, colorless crystals of H[iPr-NP] suitable
for X-ray diffraction analysis were obtained by slow
evaporation of a methanol solution at room temperature.
An X-ray crystallographic study revealed that the
molecular structure of H[iPr-NP] (Table 1, Figure 1)
resembles that of the dimethyl analogue.39 The diiso-
propylphenyl substituent is roughly perpendicular to the
o-phenylene backbone, and the two phenyl rings at the
phosphorus donor are virtually orthogonal to each other.
The isopropylmethyl groups are oriented such that they
are tilted away from the diphenylphosphino moiety,
consistent with the steric crowding of this compound as
suggested by the NMR spectroscopic data.38
(28) Ansell, C. W. G.; Cooper, M. K.; Duckworth, P. A.; McPartlin,
M.; Tasker, P. A. Inorg. Chim. Acta 1983, 76, L135.
(29) (a) Rachita, M. J .; L., H. R.; Bennett, J . L.; Brookhart, M. J .
Polym. Sci., Part A: Polym. Chem. 2000, 38, 4627-4640. (b) Bennett,
J . L.; Brookhart, M. S.; J ohnson, L. K.; Killian, C. M. WO 9830610,
1997.
(30) (a) Braunstein, P.; Pietsch, J .; Chauvin, Y.; Mercier, S.; Sau-
ssine, L.; DeCian, A.; Fischer, J . J . Chem. Soc., Dalton Trans. 1996,
3571-3574. (b) Braunstein, P.; Pietsch, J .; Chauvin, Y.; Decian, A.;
Fischer, J . J . Organomet. Chem. 1997, 529, 387-393. (c) Pietsch, J .;
Braunstein, P.; Chauvin, Y. New J . Chem. 1998, 467-472.
(31) Lapointe, A. M.; Guram, A.; Powers, T.; J andileit, B.; Boussie,
T.; Lund, C. WO 9946271, 1998.
(32) Examples are known for complexes containing chelating phos-
phine ketimine that may tautomerize to enamine; see: (a) Guan, Z.;
Marshall, W. J . Organometallics 2002, 21, 3580-3586. (b) Keim, W.;
Killat, S.; Nobile, C. F.; Suranna, G. P.; Englert, U.; Wang, R.; Mecking,
S.; Schroder, D. L. J . Organomet. Chem. 2002, 662, 150-171.
(33) Liang, L.-C.; Lin, J .-M.; Hung, C.-H. Organometallics 2003, 22,
3007-3009.
The preparation of [iPr-NP]Li(THF)2 has been com-
municated recently.38 Likewise, addition of 1 equiv of
n-BuLi to H[Me-NP] dissolved in THF at -35 °C led to
(34) Fryzuk, M. D.; Macneil, P. A.; Rettig, S. J .; Secco, A. S.; Trotter,
J . Organometallics 1982, 1, 918-930.
(35) Huang, M.-H.; Liang, L.-C. Organometallics 2004, 23, 2813-
2816.
(38) Liang, L.-C.; Lee, W.-Y.; Hung, C.-H. Inorg. Chem. 2003, 42,
(36) Klabunde, U.; Ittel, S. D. J . Mol. Catal. 1987, 41, 123.
(37) Klabunde, U.; Tulip, T. H.; Roe, D. C.; Ittel, S. D. J . Organomet.
Chem. 1987, 334, 141-156.
5471-5473.
(39) Liang, L.-C.; Huang, M.-H.; Hung, C.-H. Inorg. Chem. 2004,
43, 2166-2174.

Ta ble 1. Cr ysta llogr a p h ic Da ta for H[iP r -NP ], [Me-NP ]Li(THF )2, [iP r -NP ]NiCl(P Me3), [iP r -NP ]NiMe(P Me3), [iP r -NP ]NiP h (P Me3), [iP r -NP ]Ni(η3-CH2P h ),
a n d [Me-NP ]Ni(η3-CH2P h )
{H[iPr-NP]}2
60H64N2P2
875.07
[Me-NP]Li(THF)2
34H39LiNO2P
531.57
[iPr-NP]NiCl(PMe3)
C33H40ClNNiP2
606.76
[iPr-NP]NiMe(PMe3)
34H43NNiP2
568.34
[iPr-NP]NiPh(PMe3)
39H45NNiP2
648.41
[iPr-NP]Ni(η3-CH2Ph)
[Me-NP]Ni(η3-CH2Ph)
C33H29NNiP
529.286
1.300
formula
fw
D
C
C
C
C
C37H37NNiP
585.36
1.279
calc (g cm-3
)
1.172
1.178
1.254
1.206
1.238
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
monoclinic
P21/c
12.0940(6)
14.2831(7)
28.7245(14)
90
91.6930(10)
90
4959.7(4)
4
monoclinic
P21/c
13.818(2)
12.222(2)
17.973(3)
90
98.969
90
2998.2(9)
4
monoclinic
P21/c
10.2880(2)
17.8490(4)
18.1290(5)
90
105.0920(10)
90
3214.22(13)
4
monoclinic
P21/c
10.3530(2)
17.7380(4)
18.2700(3)
90
105.8010(10)
90
3228.35(11)
4
monoclinic
P21/c
10.611(2)
35.051(7)
9.6820(19)
90
105.03(3)
90
3477.8(12)
4
triclinic
P1h
orthorhombic
P212121
9.5852(2)
14.0420(3)
20.0909(5)
90
9.1100(3)
10.8780(3)
16.7810(7)
82.9480(10)
88.1140(10)
67.064(2)
1519.71(9)
2
90
90
2704.14(11)
4
T (K)
150(2)
150(2)
293(2)
293(2)
293(2)
293(2)
298
diffractometer
radiation, λ (Å)
2θmax (deg)
SMART CCD
Mo KR, 0.71073
55.06
30 848
11 328
SMART CCD
Mo KR, 0.71073
55.20
18 431
6837
Kappa CCD
Mo KR, 0.71073
50.14
23 876
5680
Kappa CCD
Mo KR, 0.71073
50.06
19 020
5700
Kappa CCD
Mo KR, 0.71073
50.06
10 435
5037
Kappa CCD
Mo KR, 0.71073
50.08
11 575
5291
Kappa CCD
Mo KR, 0.71073
50.06
17 634
4758
total no. of reflns
no. of indep reflns
Rint
0.0375
0.128
0.0750
0.122
0.0664
0.808
0.0538
0.722
0.0699
0.677
0.0890
0.717
0.059
0.80
absorp coeff (mm-1
)
no. of data/restraints/
params
11328/0/599
6837/0/354
5680/0/343
5700/0/344
5037/0/388
5291/0/361
4758/0/325
goodness of fit
final R indices
[I > 2σ(I)]
1.036
R1 ) 0.0471
0.803
R1 ) 0.0592
1.062
R1 ) 0.0503
1.239
R1 ) 0.0675
1.087
R1 ) 0.0661
1.124
R1 ) 0.0669
0.913
R1 ) 0.0405
wR2 ) 0.0871
R1 ) 0.0828
wR2 ) 0.0957
wR2 ) 0.1300
R1 ) 0.1397
wR2 ) 0.1524
wR2 ) 0.1381
R1 ) 0.0958
wR2 ) 0.1794
wR2 ) 0.1539
R1 ) 0.1066
wR2 ) 0.1967
wR2 ) 0.1573
R1 ) 0.1407
wR2 ) 0.2203
wR2 ) 0.1677
R1 ) 0.1213
wR2 ) 0.2206
wR2 ) 0.1076
R1 ) 0.0610
wR2 ) 0.1307
R indices (all data)

Amido Phosphine Complexes of Nickel
Organometallics, Vol. 23, No. 14, 2004 3541
NMR spectroscopy as compared to those of the corre-
sponding ligand precursors. The phosphorus atoms in
both molecules show downfield changes upon coordina-
7
tion to lithium. The 31P{1H} and Li{1H} NMR spectra
(Figure 2) are mutually consistent with the coordination
of the phosphorus donor to the quadrupolar lithium-7
center (I ) 3/2, natural abundance 92.6%). A somewhat
lower temperature, however, is required for the obser-
1
vation of J LiP in [Me-NP]Li(THF)2 than in [iPr-NP]Li-
1
(THF)2. The coupling constants J LiP of 38 and 34 Hz
for [iPr-NP]Li(THF)2 and [Me-NP]Li(THF)2, respec-
tively, are well comparable to those found for the lithium
phosphide derivatives such as [Li(tmeda)]2[1,2-C6H4-
(PPh)2] (35 Hz)40 and [Li(tmeda)]2[1,2-C6H4(PSiMe3)2]
(38 Hz).40
A single-crystal diffraction study revealed the solid-
state structure of [Me-NP]Li(THF)2. Yellow crystals of
[Me-NP]Li(THF)2 were grown from a concentrated di-
ethyl ether solution at -35 °C. As illustrated in Figure
3, this compound is a four-coordinate species with the
lithium center surrounded by two THF molecules and
the nitrogen and phosphorus donors of the amido
phosphine ligand. The geometry at lithium is distorted
tetrahedral with angles ranging from 76.63(17)° to
127.8(3)°, the most acute being associated with the
chelating amido phosphine ligand. The lithium atom is
deviated from the N-phenylene-P plane by 0.5954 Å.
A distorted tetrahedral geometry is observed for the
phosphorus donor, the bond angles involving which are
found in the range between 95.64(14)° and 147.71(14)°.
Nevertheless, the Li(1)-P(1) bond distance of 2.620(5)
Å is similar to those found in [Me2Al(CH2PMe2)2][Li-
(tmeda)] (2.606(5) Å),41,42 LiC(SiMe2CH2PPh2)3 (2.652
Å average),43 and [(tmeda)LiCH2PPh2]2 (2.686(5) Å),44
but slightly shorter than those of the tridentate ana-
logue [PNP]Li(THF)2 (2.8015 Å average).33 The dimeth-
ylphenyl ring is approximately perpendicular to the
N-phenylene-P plane. The remaining parameters are
unexceptional.
F igu r e 2. 7Li{1H} NMR (194 MHz) spectra of (a) [iPr-NP]-
Li(THF)2 (C6D6, 25 °C), (b) [Me-NP]Li(THF)2 (toluene-d8,
25 °C), (c) [Me-NP]Li(THF)2 (toluene-d8, -20 °C), and
31P{1H} NMR (202 MHz) spectra of (d) [iPr-NP]Li(THF)2
(C6D6, 25 °C), (e) [Me-NP]Li(THF)2 (toluene-d8, 25 °C), (f)
[Me-NP]Li(THF)2 (toluene-d8, -20 °C).
Syn th esis a n d Ch a r a cter iza tion of Nick el η1-
Alk yl a n d -a r yl Com p lexes. Addition of [iPr-NP]Li-
(THF)2 to NiCl2(DME) suspended in THF at -35 °C
resulted in slow dissolution of NiCl2(DME) to give a
homogeneous, deep red solution, from which diamag-
netic {[iPr-NP]NiCl}2 was isolated as a red solid in 81%
yield (eq 2). Alternatively, the chloride complex can be
prepared from the reaction of H[iPr-NP] with NiCl2-
(DME) in the presence of triethylamine in THF at room
F igu r e 3. Molecular structure of [Me-NP]Li(THF)2 with
thermal ellipsoids drawn at the 35% probability level.
Selected bond distances (Å) and angles (deg): Li(1)-O(2)
1.921(5), Li(1)-O(1) 1.942(5), Li(1)-N(1) 1.990(5), Li(1)-
P(1) 2.620(5), O(2)-Li(1)-O(1) 99.8(2), O(2)-Li(1)-N(1)
118.8(3),O(1)-Li(1)-N(1)127.8(3),O(2)-Li(1)-P(1)110.2(2),
O(1)-Li(1)-P(1) 123.1(2), N(1)-Li(1)-P(1) 76.63(17).
the isolation of the solvated lithium amide [Me-NP]Li-
(THF)2, in quantitative yield (eq 1). The solution struc-
tures of both [iPr-NP]Li(THF)2 and [Me-NP]Li(THF)2
were characterized by multinuclear NMR spectroscopy,
which is indicative of the chelating feature of these
amido phosphine ligands with respect to the lithium
center. For instance, the o-alkyl groups in both lithium
complexes are shifted relatively downfield in the 1H
(40) Hitchcock, P. B.; Lappert, M. F.; Leung, W.-P.; Yin, P. J . Chem.
Soc., Dalton Trans. 1995, 3925-3932.
(41) Karsch, H. H.; Appelt, A.; Muller, G. Chem. Commun. 1984,
1415-1416.
(42) Karsch, H. H.; Appelt, A.; Muller, G. Organometallics 1985, 4,
1624-1632.
(43) Avent, A. G.; Bonafoux, D.; eaborn, C.; Hill, M. S.; Hitchcock,
P. B.; Smith, J . D. J . Chem. Soc., Dalton Trans. 2000, 2183-2190.
(44) Blaurock, S.; Kuhl, O.; Hey-Hawkins, E. Organometallics 1997,
16, 807-808.

3542 Organometallics, Vol. 23, No. 14, 2004
Liang et al.
Sch em e 1
temperature. Attempts to grow crystals suitable for
X-ray diffraction analysis were not successful. We
tentatively formulate this compound as a chloride-
bridged dimer, presumably in the solid state, on the
basis of its facile association with Lewis bases (vide
infra). The phosphorus donor of {[iPr-NP]NiCl}2 in C6D6
appears as a broad singlet resonance at 32.45 ppm (∆v1/2
) 80 Hz) in the 31P{1H} NMR spectroscopy, a value that
is shifted significantly downfield from those of H[iPr-
NP] at -20.11 ppm and [iPr-NP]Li(THF)2 at -11.99
ppm.38 Similar to those found in H[iPr-NP] and [iPr-
NP]Li(THF)2, the isopropylmethyl groups in {[iPr-NP]-
or PMePh2 to {[iPr-NP]NiCl}2 resulted in a yellowish
green or emerald solution, whose 31P{1H} NMR spec-
trum at room temperature revealed a broad signal for
the amido phosphine ligand, likely due to the formation
of the two possible geometric isomers. A fast equilibrium
between dissociation and association of the external
base in these presumed isomeric mixtures might also
be involved.
The preparation of nickel hydrocarbyl complexes
containing the bidentate [NP]- ligands is of particular
interest in view of the parallel comparison with the
tridentate [PNP]- analogues33 and the potential ap-
plications for organic synthesis and homogeneous ca-
talysis. Attempts to prepare well-defined alkyl or aryl
complexes from the reactions of {[iPr-NP]NiCl}2 with a
variety of Grignard reagents were not successful. Dia-
magnetic, ruby [iPr-NP]NiMe(PMe3), however, was iso-
lated in high yield from the reaction of [iPr-NP]NiCl-
(PMe3) with MeMgCl in THF at -35 °C. In contrast to
[iPr-NP]NiCl(PMe3), [iPr-NP]NiMe(PMe3) exists as a
mixture of two geometric isomers with a relative ratio
of ca. 9:1, as indicated by 31P{1H} NMR spectroscopy.
The coupling constant of 30 Hz observed for the major
isomer found in the THF aliquot indicates that the two
phosphorus donors are mutually cis to each other,
whereas that of 302 Hz for the minor corresponds to a
trans relationship. The major component exhibits a
doublet resonance centered at 35.60 ppm for the phos-
phorus donor of the amido phosphine ligand, whereas
the minor component appears at 38.95 ppm. The nickel-
bound methyl hydrogen atoms in both isomers appear
as a doublet of doublets resonance at -0.12 and -0.42
ppm for major and minor components, respectively, as
a consequence of internuclear interaction with two
chemically inequivalent phosphorus donors.
1
NiCl}2 are diastereotopic, as evidenced by H and 13C
NMR spectroscopy, implying restricted rotation about
the N-Ar bond.38,45 Analogous reactions involving the
[Me-NP]- ligand have so far been inconclusive. We
suspect that concomitant formation of [Me-NP]2Ni and
the desired chloride complex becomes possible due to
the smaller size of the [Me-NP]- ligand.
[iPr-NP]Li(THF)2 NiCl (DME)8
2
{[iPr-NP]NiCl}2 7NiCl2(DME), NEt3 H[iPr-NP] (2)
Treatment of {[iPr-NP]NiCl}2 with PMe3 in THF at
room temperature produced high yield of diamagnetic
[iPr-NP]NiCl(PMe3) as an emerald solid (Scheme 1). The
31P{1H} NMR spectroscopy at room temperature exhib-
its two doublet resonances with equal intensity at 47.29
and -16.98 ppm for [iPr-NP]- and PMe3, respectively.
The coupling constant of 88 Hz is consistent with a cis
relationship between the two phosphorus donors. This
phenomenon is notably different from that found in the
closely related system involving a trimethylsilyl-sub-
stituted amide as shown in eq 3, in which two isomers
are present in solution with the trans form being
predominant.46 Addition of Lewis bases such as pyridine
Single crystals of [iPr-NP]NiCl(PMe3) suitable for
X-ray diffraction analysis were grown by layering pen-
tane on a concentrated THF solution at -35 °C, while
those of [iPr-NP]NiMe(PMe3) were obtained by slow
evaporation of a concentrated benzene solution at room
temperature. As depicted in Figure 4, the solid-state
(45) Gue´rin, F.; McConville, D. H.; Payne, N. C. Organometallics
1996, 15, 5085-5089.
(46) Klein, H.-F.; Beck, R.; Hetche, O. Eur. J . Inorg. Chem. 2003,
232-239.

Amido Phosphine Complexes of Nickel
Organometallics, Vol. 23, No. 14, 2004 3543
F igu r e 4. Molecular structures of (a) [iPr-NP]NiCl(PMe3) and (b) the major isomer of [iPr-NP]NiMe(PMe3) with thermal
ellipsoids drawn at the 35% probability level. Selected bond distances (Å) and angles (deg) for [iPr-NP]NiCl(PMe3): Ni-
(1)-N(1) 1.923(3), Ni(1)-P(1) 2.1556(10), Ni(1)-P(2) 2.1941(12), Ni(1)-Cl(1) 2.2006(11), N(1)-Ni(1)-P(1) 85.21(9), N(1)-
Ni(1)-P(2) 175.17(10), P(1)-Ni(1)-P(2) 97.51(4), N(1)-Ni(1)-Cl(1) 93.54(9), P(1)-Ni(1)-Cl(1) 177.68(5), P(2)-Ni(1)-
Cl(1) 83.88(5). Selected bond distances (Å) and angles (deg) for [iPr-NP]NiMe(PMe3): Ni(1)-N(1) 1.939(3), Ni(1)-C(31)
2.035(4), Ni(1)-P(2) 2.1475(12), Ni(1)-P(1) 2.2009(12), N(1)-Ni(1)-C(31) 92.15(15), N(1)-Ni(1)-P(2) 173.48(11), C(31)-
Ni(1)-P(2) 83.66(12), N(1)-Ni(1)-P(1) 85.02(10), C(31)-Ni(1)-P(1) 176.35(12), P(2)-Ni(1)-P(1) 99.36(5).
2
structures are consistent with the solution structures
observed by NMR spectroscopy. The coordinated PMe3
is cis to the phosphorus donor of the amido phosphine
ligand with P-Ni-P angles of 97.51(4)° and 99.36(5)°
for [iPr-NP]NiCl(PMe3) and [iPr-NP]NiMe(PMe3), re-
spectively. The nickel center in both [iPr-NP]NiCl(PMe3)
and [iPr-NP]NiMe(PMe3) lies perfectly on the square
plane defined by the four donor atoms. The N(1)-Ni-
(1)-P(1) bonding angles of 85.21(9)° in [iPr-NP]NiCl-
(PMe3) and 85.02(10)° in [iPr-NP]NiMe(PMe3) are simi-
lar to those of the nickel derivatives featuring a five-
membered metallacycle such as [(o-Ph2PC6H4NHMe)-
NiCl(PMe3)]PF6 (87.0(1)°)47 and the SHOP catalyst [Ph2-
PCHdC(Ph)O]Ni(Ph)(PPh3) (86.5°).2 The Ni-N dis-
tances of ca. 1.93 Å for both molecules are slightly longer
than those of nickel diarylamide complexes such as [Ni-
(NPh2)2]2 (1.828 Å average for terminal amides)48 and
(BQA)NiCl (1.8586(14) Å, BQA ) bis(8-quinolinyl)-
amide),49 likely implying the significant steric demand
of the amido phosphine ligand employed. As expected,
the diisopropylphenyl ring is roughly perpendicular to
the N-phenylene-P plane with dihedral angles of 93.8°
for [iPr-NP]NiCl(PMe3) and 93.3° for [iPr-NP]NiMe-
(PMe3), thus providing steric protection for the axial
faces of the nickel center.
resonance at 152 ppm with coupling constants J CP of
39 and 34 Hz, values that are anticipated for an ipso
carbon atom concomitantly experiencing two chemically
inequivalent phosphorus donors in the cis positions.
Similar to those observed for [iPr-NP]NiCl(PMe3) and
[iPr-NP]NiMe(PMe3), the isopropylmethyl groups in [i-
Pr-NP]NiPh(PMe3) appear as two doublet resonances
in the 1H NMR spectroscopy, again suggesting restricted
rotation about the N-Ar bond due to significant steric
crowding of these molecules.
Crystals of [iPr-NP]NiPh(PMe3) suitable for X-ray
analysis were grown by layering pentane on a concen-
trated diethyl ether solution at -35 °C. Figure 5
illustrates the molecular structure that is in accord with
that determined by NMR spectroscopy. The Ni-N, Ni-
P, and Ni-C distances and the N-Ni-P angle of the
amido phosphine ligand in [iPr-NP]NiPh(PMe3) are all
comparable to the corresponding values found in [iPr-
NP]NiCl(PMe3) and [iPr-NP]NiMe(PMe3). Considerable
deviation, however, is observed for the phenyl deriva-
tive. The P(2) and C(19) atoms are notably displaced
from the N-phenylene-P plane by 0.3703 and 0.4093
Å, respectively (Figure 5b). The steric repulsion between
the amido substituent and the PMe3 ligand seems
significant. As a result, the diisopropylphenyl ring is
tilted from the ideal orthogonal orientation with respect
to the o-phenylene plane (dihedral angle 77.5°). The
P-Ni-P angle of 163.76(9)° is thus much smaller than
the ideal value of 180°.
Syn th esis a n d Ch a r a cter iza tion of Nick el η3-
Ben zyl Com p lexes. Prior dissociation or abstraction
of the coordinated PMe3 is anticipated to be a prereq-
uisite for [iPr-NP]NiX(PMe3) (X ) Me, Ph) if the
catalytic oligomerization or polymerization of olefins is
the goal. The preparation of compounds that do not
require the coordination of external bases is thus
intriguing. The synthesis of [iPr-NP]Ni(η3-CH2Ph) was
pursued from the reactions of either {[iPr-NP]NiCl}2 or
[iPr-NP]NiCl(PMe3) with PhCH2MgCl as shown in
Scheme 1. Interestingly, the coordinated PMe3 dissoci-
In contrast to [iPr-NP]NiCl(PMe3) and [iPr-NP]NiMe-
(PMe3), the phenyl complex [iPr-NP]NiPh(PMe3) (Scheme
1) possesses the PMe3 ligand exclusively trans to the
phosphorus donor of the amido phosphine ligand. 31P-
{1H} NMR spectroscopy reveals a pair of doublet
2
resonances with J PP of 288 Hz. It is interesting to note
that the trans relationship for the two phosphorus
donors found in [iPr-NP]NiPh(PMe3) is reminiscent of
that of the SHOP catalyst [Ph2PCHdC(Ph)O]Ni(Ph)-
(PPh3).2 The CR atom is observed as a doublet of doublets
(47) Crociani, L.; Tisato, F.; Refosco, F.; Bandoli, G.; Corain, B. Eur.
J . Inorg. Chem. 1998, 1689-1697.
(48) Hope, H.; Olmstead, M. M.; Murray, B. D.; Power, P. P. J . Am.
Chem. Soc. 1985, 107, 712-713.
(49) Peters, J . C.; Harkins, S. B.; Brown, S. D.; Day, M. W. Inorg.
Chem. 2001, 40, 5083-5091.

3544 Organometallics, Vol. 23, No. 14, 2004
Liang et al.
F igu r e 5. Two views of the molecular structure of [iPr-NP]NiPh(PMe3) with thermal ellipsoids drawn at the 35% probability
level. Selected bond distances (Å) and angles (deg): Ni(1)-C(19) 1.923(7), Ni(1)-N(1) 1.947(5), Ni(1)-P(1) 2.149(2), Ni-
(1)-P(2) 2.238(2), C(19)-Ni(1)-N(1) 167.6(3), C(19)-Ni(1)-P(1) 85.7(2), N(1)-Ni(1)-P(1) 85.94(17), C(19)-Ni(1)-P(2)
85.1(2), N(1)-Ni(1)-P(2) 105.14(17), P(1)-Ni(1)-P(2) 163.76(9).
ates from [iPr-NP]NiCl(PMe3) upon the reaction with
PhCH2MgCl. Alternatively, this benzyl complex is ac-
cessible in high isolated yield from the reaction of Ni-
(COD)2 with PhCH2Cl in the presence of [iPr-NP]Li-
(THF)2 (eq 4). This strategy takes advantage of facile
oxidative addition of benzyl halides to zerovalent nickel50
and avoids the prerequisite preparation of the chloride
precursors, thereby providing a valuable entry to the
sterically less bulky [Me-NP]- derivatives.
in the amount of sp2 character of the CR atom.52,53
A
variable-temperature H NMR study of [iPr-NP]Ni(η3-
CH2Ph) (42.6 mM in toluene-d8) revealed that the two
benzylic hydrogen atoms are equivalent at tempera-
tures as low as -80 °C, suggesting a rapid suprafacial
rearrangement of the benzyl ligand,54,55 as illustrated
in eq 5. The benzyl complexes are thermally stable, even
at elevated temperatures. For instance, no decomposi-
tion was observed when [iPr-NP]Ni(η3-CH2Ph) (24.4 mM
in C6D6) was heated to 100 °C for >3 days, as evidenced
1
1
by H and 31P{1H} NMR spectroscopy.
The solution structures of the benzyl complexes were
characterized by multinuclear NMR spectroscopy. The
phosphorus donor in [iPr-NP]Ni(η3-CH2Ph) and [Me-NP]-
Ni(η3-CH2Ph) is observed as a sharp singlet resonance
at 36.24 and 34.84 ppm, respectively, in the 31P{1H}
NMR spectroscopy. Both molecules exhibit a doublet
Crystals of [iPr-NP]Ni(η3-CH2Ph) and [Me-NP]Ni(η3-
CH2Ph) suitable for X-ray diffraction analysis were
grown by slow evaporation of concentrated benzene
solutions at room temperature. As depicted in Figure
6, the geometry of the nickel center in both molecules
is best described as distorted square planar with the
CR atom being cis to the phosphorus donor of the amido
phosphine ligand. The hapticity of the benzyl ligand is
consistent with that suggested by the NMR spectros-
copy. In particular, the acute Ni-CR-Ph angles of
73.6(3)° and 71.8(2)° for [iPr-NP]Ni(η3-CH2Ph) and [Me-
NP]Ni(η3-CH2Ph), respectively, are markedly smaller
than that expected for an sp3 carbon atom, but well
comparable to those found in η3-benzyl complexes such
as [(iPrO)3P]2Rh(η3-CH2C6Me5) (75°),55 [Ph2PC6H4C(O-
B(C6F5)3)O-κ2P,O]Ni(η3-CH2Ph) (73.6(3)°),4 and {ArNd
C(Me)CdNAr[O-B(C6F5)3]-κ2N,N′}Ni(η3-CH2Ph) (70.6(4)°,
3
resonance at ca. 1.56 ppm with J HP of 4 Hz for the
1
benzylic hydrogen atoms in the H NMR spectroscopy
2
and a doublet at ca. 28 ppm with J CP of 9 Hz for the
benzylic carbon in the 13C{1H} and DEPT 13C NMR
spectroscopy. These values are well comparable to those
of nickel η3-benzyl complexes supported by phosphine-
derived ligands in which the phosphorus donor is cis to
the benzylic methylene group.4 The η3 feature of the
benzyl ligand51 maintained in solution is unambiguously
1
elucidated by J CH of ca. 152 Hz for the NiCH2 moiety
in [iPr-NP]Ni(η3-CH2Ph) and [Me-NP]Ni(η3-CH2Ph). The
observed coupling constant is significantly larger than
1
the expected J CH value of 122 Hz for a normal sp3
carbon atom. The increased coupling constant parallels
a decreased Ni-CR-Ph angle that leads to an increase
Ar ) 2,6-C6H3 Pr2).24 The Ni-C distances to the ipso
i
and ortho carbon atoms are short, although in both
(50) Anderson, T. J .; Vicic, D. A. Organometallics 2004, 23, 623-
625.
(52) Latesky, S. L.; McMullen, A. K.; Niccolai, G. P.; Rothwell, I.
P.; Huffman, J . C. Organometallics 1985, 4, 902-908.
(53) Giesbrecht, G. R.; Whitener, G. D.; Arnold, J . Organometallics
2000, 19, 2809-2812.
(51) The ortho protons of the η3-benzyl group tend to shift upfield
at <6.8 ppm in the 1H NMR spectroscopy; for instance, see ref 52. Such
signals are observed for both [iPr-NP]Ni(η3-CH2Ph) and [Me-NP]Ni-
(η3-CH2Ph), but assignment of the ortho hydrogen atoms cannot be
absolutely certain due to the aromatic signals arising from the amido
phosphine ligands.
(54) Carmona, E.; Paneque, M.; Poveda, M. Polyhedron 1989, 8,
285-291.
(55) Burch, R. R.; Nuetterties, E. L.; Day, V. W. Organometallics
1982, 1, 188-197.

Amido Phosphine Complexes of Nickel
Organometallics, Vol. 23, No. 14, 2004 3545
F igu r e 6. Molecular structures of (a) [iPr-NP]Ni(η3-CH2Ph) and (b) [Me-NP]Ni(η3-CH2Ph) with thermal ellipsoids drawn
at the 35% probability level. Selected bond distances (Å) and angles (deg) for [iPr-NP]Ni(η3-CH2Ph): Ni(1)-(1) 1.908(4),
Ni(1)-C(19) 1.973(6), Ni(1)-C(20) 2.088(6), Ni(1)-P(1) 2.1231(15), Ni(1)-C(21) 2.192(6), N(1)-Ni(1)-C(19) 173.3(3), N(1)-
Ni(1)-C(20) 137.3(2), C(19)-Ni(1)-C(20) 41.3(2), N(1)-Ni(1)-P(1) 88.11(13), C(19)-Ni(1)-P(1) 94.92(19), C(20)-Ni(1)-
P(1) 133.59(18), N(1)-Ni(1)-C(21) 104.4(2), C(19)-Ni(1)-C(21) 71.5(3), C(20)-Ni(1)-C(21) 38.1(2), P(1)-Ni(1)-C(21)
162.82(18), C(20)-C(19)-Ni(1) 73.6(3). Selected bond distances (Å) and angles (deg) for [Me-NP]Ni(η3-CH2Ph): Ni(1)-
N(1) 1.900(3), Ni(1)-C(27) 1.973(4), Ni(1)-C(28) 2.039(4), Ni(1)-P(1) 2.1176(11), Ni(1)-C(29) 2.196(4), N(1)-Ni(1)-C(27)
172.51(18), N(1)-Ni(1)-C(28) 136.95(17), C(27)-Ni(1)-C(28) 41.39(19), N(1)-Ni(1)-P(1) 88.36(10), C(27)-Ni(1)-P(1) 95.64-
(15), C(28)-Ni(1)-P(1) 132.67(14), N(1)-Ni(1)-C(29) 103.25(15), C(27)-Ni(1)-C(29) 71.96(19), C(28)-Ni(1)-C(29) 39.12-
(17), P(1)-Ni(1)-C(29) 165.93(13), C(28)-C(27)-Ni(1) 71.8(2).
are referenced using the residual solvent peak at δ 128.39 for
C6D6. The assignment of the carbon atoms for all new
compounds is based on the DEPT 13C NMR spectroscopy. 31P
and 7Li NMR spectra are referenced externally using 85%
H3PO4 at δ 0 and LiCl in D2O at δ 0, respectively. 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.
cases longer than that to CR. In accord with the small
CR-Ni-Cortho angles, the N-Ni-P angles of 88.11(13)°
for [iPr-NP]Ni(η3-CH2Ph) and 88.36(10)° for [Me-NP]Ni-
(η3-CH2Ph) are slightly wider than those found in [iPr-
NP]NiCl(PMe3), [iPr-NP]NiMe(PMe3), and [iPr-NP]NiPh-
(PMe3).
Con clu sion s
Ma ter ia ls. Compounds N-(2-diphenylphosphinophenyl)-2,6-
diisopropylaniline (H[iPr-NP]),38 N-(2-diphenylphosphinophe-
We have prepared and characterized a series of
divalent nickel complexes containing bidentate diary-
lamido phosphine ligands. The synthetic strategies are
versatile, particularly for the diisopropylphenyl deriva-
tives. The exclusive formation of one of the two possible
geometric isomers for [iPr-NP]NiCl(PMe3) and [iPr-NP]-
NiPh(PMe3) is unique, which is in contrast to the result
obtained for [iPr-NP]NiMe(PMe3). The benzylic meth-
ylene groups in [iPr-NP]Ni(η3-CH2Ph) and [Me-NP]Ni-
(η3-CH2Ph) are exclusively cis to the phosphorus donor
of the amido phosphine ligands. The solution structures
of these molecules determined by multinuclear NMR
spectroscopy are all in good agreement with the solid-
state structures by X-ray crystallography. Of particular
interest is the geometric analogy of [iPr-NP]NiPh(PMe3)
to the SHOP catalysts2 in which the two phosphorus
donors are mutually trans. Chemistry involving the
catalytic activities of these new molecules will be the
subject of further reports.
nyl)-2,6-dimethylaniline (H[Me-NP]),39 and [iPr-NP]Li(THF)2
38
were prepared according to the procedures reported previously.
All other chemicals were obtained from commercial vendors
and used as received.
X-r a y Cr ysta llogr a p h y. Table 1 summarizes the crystal-
lographic data for all structurally characterized compounds.
Data for compounds H[iPr-NP] and [Me-NP]Li(THF)2 were
collected on a Bruker SMART 1000 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 SHELXTL.
All full-weight non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were placed in calculated positions.
Data for compounds [iPr-NP]NiCl(PMe3), [iPr-NP]NiMe(PMe3),
[iPr-NP]NiPh(PMe3), [iPr-NP]Ni(η3-CH2Ph), and [Me-NP]Ni-
(η3-CH2Ph) were collected on a Bruker-Nonius Kappa 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 the maXus or WinGX crystallographic software package.
All full-weight non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were placed in calculated positions.
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless otherwise specified, all ex-
periments 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 instruments. Chemical shifts
(δ) are listed as parts per million downfield from tetrameth-
ylsilane, and coupling constants (J ) and peak widths at half-
height (∆v1/2) are in hertz. 1H NMR spectra are referenced
using the residual solvent peak at δ 7.16 for C6D6 and δ 2.09
for toluene-d8 (the most upfield resonance). 13C NMR spectra
Syn th esis of [Me-NP ]Li(THF )2. To a solution of H[Me-
NP] (2.0 g, 5.24 mmol) in THF (15 mL) at -35 °C was added
n-BuLi (3.3 mL, 5.24 mmol, 1 equiv). The reaction mixture
was naturally warmed to room temperature and stirred for 3
h. All volatiles were removed in vacuo. The red viscous residue
was triturated with pentane (15 mL) to yield a yellow solid.
The yellow solid was isolated from the orange solution, washed
with pentane (5 mL × 3), and dried in vacuo; yield 2.67 g
(99%). Recrystallization of the yellow solid from a concentrated
diethyl ether solution at -35 °C gave yellow crystals suitable

3546 Organometallics, Vol. 23, No. 14, 2004
Liang et al.
1
2
2
for X-ray crystallography. H NMR (C6D6, 500 MHz): δ 7.58
121.4 MHz): δ 46.89 (d, J PP ) 88 Hz), -15.75 (d, J PP ) 88
Hz). 13C{1H} NMR (C6D6, 125.5 MHz): δ 146.47, 134.24,
134.12, 134.05, 131.91, 131.44, 129.37, 129.20, 125.60, 124.09,
116.20,113.66, 29.14 (CHMe2), 25.27 (CHMe2), 24.97 (CHMe2),
(m, 4, Ar), 7.23 (d, 2, Ar), 7.07-7.16 (m, 8, Ar), 6.97 (m, 1, Ar),
6.38 (m, 1, Ar), 6.33 (m, 1, Ar), 3.23 (m, 8, OCH2CH2), 2.26 (s,
6, CH3), 1.19 (m, 8, OCH2CH2). 31P{1H} NMR (C6D6, 202
MHz): δ -13.66 (br s, ∆v1/2 ) 75 Hz). 31P{1H} NMR (toluene-
d8, 202 MHz): δ -12.96. 31P{1H} NMR (toluene-d8, -20 °C,
1
3
16.08 (dd, J CP ) 30.92, J CP ) 9.17, PMe3). Anal. Calcd for
33H40ClNNiP2: C, 65.32; H, 6.64; N, 2.31. Found: C, 64.72;
C
202 MHz): δ -12.72 (1:1:1:1 q, J LiP ) 34 Hz). Li{1H} NMR
H, 6.71; N, 2.35.
1
7
(C6D6, 194 MHz): δ 1.37 (br s, ∆v1/2 ) 21 Hz). Li{1H} NMR
7
Syn th esis of [iP r -NP ]NiMe(P Me3). Solid [iPr-NP]NiCl-
(PMe3) (56.7 mg, 0.094 mmol) was dissolved in THF (3 mL)
and cooled to -35 °C. To this was added MeMgCl (0.03 mL, 3
M in THF, Aldrich, 0.094 mmol) dropwise. The reaction
mixture was naturally warmed to room temperature and
stirred overnight. An aliquot was taken and examined by 31P-
{1H} NMR spectroscopy, which indicated complete consump-
tion of [iPr-NP]NiCl(PMe3) and exhibited two pairs of doublet
resonances with the relative intensities of ca. 9:1 (2J PP ) 30
(toluene-d8, 194 MHz): δ 2.08. 7Li{1H} NMR (toluene-d8, -20
°C, 194 MHz): δ 2.12 (d, 1J LiP ) 34 Hz). 13C NMR (C6D6, 125.5
MHz): δ 163.88 (J CP ) 21.63, CP), 154.81, 138.20 (PCCN),
135.69 (CH), 134.38 (J CP ) 16.25, CH), 134.06, 132.74 (CH),
129.00 (CH), 128.88 (J CP ) 6.63, CH), 128.68 (CH), 120.65
(CH), 114.00 (J CP ) 3.75 Hz), 113.01 (CH), 110.47 (CH), 68.70
(OCH2CH2), 25.61 (OCH2CH2), 19.73 (CH3).
Syn th esis of {[iP r -NP ]NiCl}2. Method 1: Solid NiCl2-
(DME) (400 mg, 1.818 mmol) was suspended in THF (60 mL)
and cooled to -35 °C. To this was added dropwise a solution
of [iPr-NP]Li(THF)2 (1.0672 g, 1.818 mmol) in THF (20 mL)
at -35 °C. Upon addition, the reaction mixture became red in
color and the suspended NiCl2(DME) dissolved. The solution
was stirred at room temperature overnight. All volatiles were
removed in vacuo. The resulting viscous, reddish-brown resi-
due was dissolved in CH2Cl2 (15 mL) and passed through a
pad of Celite, which was further washed with CH2Cl2 (2 mL)
until the washings were colorless. The filtrate was evaporated
in vacuo to dryness to give the product as a deep red solid,
which was gently washed with diethyl ether (3 mL × 2) and
dried in vacuo; yield 780.6 mg (81%). Method 2: Solid NiCl2-
(DME) (100 mg, 0.454 mmol) was suspended in THF (15 mL)
at room temperature. To this was added a THF solution (5
mL) of H[iPr-NP] (198.9 mg, 0.454 mmol). The reaction mixture
was stirred at room temperature for 30 min, and NEt3 (0.095
mL, 0.681 mmol, 1.5 equiv) was added. After being stirred for
1 h, the reaction mixture was evaporated to dryness under
reduced pressure. The residue was triturated with pentane (2
mL × 2). The product was extracted with CH2Cl2 (10 mL) and
filtered through a pad of Celite. Solvent was removed in vacuo
to afford the crude product as a brick-red solid. The product
was purified by dissolving the solid in a minimal amount of
THF (ca. 1 mL) followed by addition of pentane (3 mL) to
induce the precipitation of a red solid. The red solid was
isolated by decantation of the solution, washed with pentane,
2
Hz for major and J PP ) 302 Hz for minor). All volatiles were
removed in vacuo. The red residue thus obtained was tritu-
rated with pentane (2 mL × 2), extracted with benzene (6 mL),
and filtered through a pad of Celite. The Celite pad was further
washed with benzene (1 mL × 2) until the washings became
colorless. Solvent was removed in vacuo to give the product
as a ruby solid. Crystals suitable for X-ray crystallography
were grown by slow evaporation of a concentrated benzene
solution at room temperature; yield 43.6 mg (79%). The 1H
and 31P{1H} NMR spectra of the X-ray quality crystals
indicated the presence of two geometric isomers in a ratio of
ca. 3:1 with the major corresponding to a cis relationship
between the two phosphorus donors. Spectroscopic data for the
major isomer: 1H NMR (C6D6, 500 MHz): δ 7.78 (m, 4, Ar),
7.40 (m, 3, Ar), 7.08 (m, 2, Ar), 7.05 (m, 4, Ar), 6.92 (dt, 1, Ar),
6.87 (dt, 1, Ar), 6.28 (t, 1, Ar), 6.12 (dd, 1, Ar), 3.90 (septet, 2,
CHMe2), 1.46 (d, 6, CHMe2), 1.24 (d, 6, CHMe2), 0.70 (d, 9,
3
NP
3
PMe3
2
J HP ) 9 Hz, PMe3), -0.12 (dd, 3, J HP ) 4.0 Hz, J HP
)
7.5 Hz, NiMe). 31P{1H} NMR (C6D6, 202.3 MHz): δ 35.60 (d,
2J PP ) 25.49 Hz, NP), -7.46 (d, J PP ) 25.49 Hz, PMe3). 31P-
2
{1H} NMR (THF, 80.953 MHz): δ 35.25 (d, J PP ) 29.95 Hz,
2
NP), -6.26 (d, J PP ) 29.95 Hz, PMe3). 13C{1H} NMR (C6D6,
2
125.678 MHz):56 δ 28.55 (s, CHMe2), 25.62 (s, CHMe2), 24.65
(s, CHMe2), 17.03 (dd, 1J CP ) 30 Hz, 3J CP ) 5 Hz, PMe3), 11.13
2
PMe3
2
NP
(dd, J CP
) 38.84 Hz, J CP ) 58.69 Hz, NiMe). Spectro-
scopic data for the minor isomer: 1H NMR (C6D6, 500 MHz):
56
δ 3.84 (septet, 2, CHMe2), 1.30 (d, 6, CHMe2), 1.18 (d, 6,
1
2
4
and dried in vacuo; yield 150 mg (62%). H NMR (C6D6, 500
CHMe2), 0.55 (dd, 9, J HP ) 7 Hz, J HP ) 1 Hz, PMe3), -0.42
(dd, 3, 3J HP ) 12 Hz, 3J HPPMe3 ) 7.5 Hz, NiMe). 31P{1H} NMR
NP
MHz): δ 7.75 (m, 4, Ar), 7.09 (m, 3, Ar), 7.00-7.04 (m, 6, Ar),
6.79 (m, 1, Ar), 6.64 (t, 1, Ar), 6.09 (t, 1, Ar), 5.85 (d, 1, Ar),
3.94 (septet, 2, CHMe2), 1.51 (d, 6, CHMe2), 1.11 (d, 6, CHMe2).
31P{1H} NMR (C6D6, 202.5 MHz): δ 32.45 (br s, ∆v1/2 ) 80 Hz).
31P{1H} NMR (THF, 121.4 MHz): δ 33.06 (br s). 13C NMR
(C6D6, 125.5 MHz): δ 167.63, 147.92, 145.77, 133.88 (CH),
133.64 (CH), 132.81 (CH), 131.27 (CH), 129.92 (J CP ) 44.80),
129.26 (CH), 125.93 (CH), 124.12 (CH), 116.71 (CH), 114.05
(CH), 117.5 (J CP ) 37.65). Anal. Calcd for (C30H31ClNNiP)2:
C, 67.90; H, 5.89; N, 2.64. Found: C, 68.12; H, 6.44; N, 2.51.
Syn th esis of [iP r -NP ]NiCl(P Me3). PMe3 (0.38 mL, 1.0 M
in THF, Aldrich, 0.38 mmol, 1 equiv per nickel) was added to
a red solution of {[iPr-NP]NiCl}2 (200 mg, 0.19 mmol) in THF
(8 mL) at room temperature. The solution became green in
color over the course of 30 min. After being stirred at room
temperature overnight, the solution was evaporated to dryness
under reduced pressure. The product was isolated as a green
solid, which was spectroscopically pure by 31P{1H} NMR
spectroscopy; yield 186.8 mg (81.6%). Emerald cubic crystals
of [iPr-NP]NiCl(PMe3) suitable for X-ray diffraction analysis
were grown by layering pentane on a concentrated THF
(C6D6, 202.3 MHz): δ 38.95 (d, 2J PP ) 301.04 Hz, NP), -17.96
(d, J PP ) 301.04 Hz, PMe3). 31P{1H} NMR (THF, 80.953
2
2
2
MHz): δ 38.66 (d, J PP ) 302.3 Hz, NP), -17.10 (d, J PP
)
302.3 Hz, PMe3). 13C{1H} NMR (C6D6, 125.678 MHz):56 δ 28.85
(s, CHMe2), 24.96 (s, CHMe2), 24.21 (s, CHMe2), 13.45 (d, 1J CP
) 23 Hz, PMe3), NiMe not found. Anal. Calcd for C34H43
NNiP2: C, 69.65; H, 7.39; N, 2.39. Found: C, 69.32; H, 7.35;
-
N, 2.37.
Syn th esis of [iP r -NP ]NiP h (P Me3). Solid [iPr-NP]NiCl-
(PMe3) (110 mg, 0.181 mmol) was dissolved in THF (6 mL)
and cooled to -35 °C. To this was added PhMgCl (0.09 mL,
2.05 M in THF, Strem, 0.181 mmol) dropwise. The reaction
mixture was naturally warmed to room temperature and
stirred overnight. All volatiles were removed in vacuo. The red
solid residue was extracted with benzene (3 mL) and filtered
through a pad of Celite, which was further washed with
benzene (1 mL × 2) until the washings became colorless.
Solvent was removed in vacuo to give the product as a
brownish red solid; yield 100.8 mg (86%). Crystals suitable for
X-ray analysis were grown by layering pentane on a concen-
trated diethyl ether solution at -35 °C. 1H NMR (C6D6, 500
MHz): δ 7.65 (m, 4, Ar), 7.46 (m, 1, Ar), 7.22 (m, 6, Ar), 7.04
1
solution at -35 °C. H NMR (C6D6, 500 MHz): δ 7.81 (m, 4,
Ar), 7.34 (m, 3, Ar), 7.03 (m, 2, Ar), 6.99 (m, 4, Ar), 6.79 (t, 1,
Ar), 6.71 (m, 1, Ar), 6.21 (t, 1, Ar), 6.08 (m, 1, Ar), 3.94 (septet,
2, CHMe2), 1.65 (d, 6, CHMe2), 1.20 (d, 6, CHMe2), 0.74 (d, 9,
2J HP ) 9.5, PMe3). 31P{1H} NMR (C6D6, 202.5 MHz): δ 47.29
(d, 2J PP ) 88 Hz), -16.98 (d, 2J PP ) 88 Hz). 31P{1H} NMR (THF,
(56) The complete assignment was hampered by the complicated
aromatic signals, primarily due to the relatively small intensities of
the minor isomer. Only aliphatic signals are reported.

Amido Phosphine Complexes of Nickel
Organometallics, Vol. 23, No. 14, 2004 3547
(m, 6, Ar), 6.87 (td, 1, Ar), 6.65 (t, 2, Ar), 6.24 (t, 1, Ar), 5.99
(dd, 1, Ar), 4.11 (septet, 2, CHMe2), 1.44 (d, 6, CHMe2), 1.25
(d, 6, CHMe2), 0.38 (d, 9, 2J HP ) 8, PMe3). 31P{1H} NMR (C6D6,
150.87, 145.36, 134.58 (CH), 134.35, 134.12, 133.30 (CH),
133.21 (CH), 130.62 (CH), 129.24 (J CP ) 9.91, CH), 126.82
(CH), 124.42 (CH), 123.97 (CH), 117.45, 114.82 (CH), 114.73
(CH), 112.42 (J CP ) 7.28, CH), 110.28 (J CP ) 5.52, CH), 28.71
2
2
202.3 MHz): δ 33.00 (d, J PP ) 288, NP), -22.32 (d, J PP
)
288, PMe3). 31P{1H} NMR (THF, 121.42 MHz): δ 33.16 (d, 2J PP
(CHMe2), 28.53 (2J CP ) 9.04, J CH ) 152, NiCH2Ph), 24.26
1
) 286, NP), -21.24 (d, 2J PP ) 293, PMe3). 13C{1H} NMR (C6D6,
(CHMe2). Anal. Calcd for C37H38NNiP: C, 75.79; H, 6.53; N,
2.39. Found: C, 75.76; H, 6.75; N, 2.33.
2
125.679 MHz): δ 168.56 (d, J CP ) 33.68), 151.90 (dd, J CP
)
2
39.1, J CP ) 33.7, NiC), 147.99, 145.89, 139.00 (CH), 134.7
(CH), 133.72 (CH), 133.18 (CH), 132.98 (d, J CP ) 50.90), 130.19
(CH), 128.67 (CH), 128.20 (CH), 126.73 (CH), 124.95 (CH),
121.97 (CH), 115.14 (d, J CP ) 44.62), 114.53 (d, J CP ) 12.69,
CH), 112.54 (d, J CP ) 7.29, CH), 29.13 (CHMe2), 25.04
Syn th esis of [Me-NP ]Ni(η3-CH2P h ). Diethyl ether (6 mL)
was added to a solid mixture of [Me-NP]Li(THF)2 (200 mg,
0.38 mmol) and Ni(COD)2 (103.5 mg, 0.38 mmol). To this
suspension was added PhCH2Cl (3.8 mL, 0.1 M stock solution
in diethyl ether, 0.38 mmol) at room temperature. The reaction
mixture was stirred at room temperature for 3 h. All volatiles
were removed in vacuo. The product was extracted from the
resulting solid residue with benzene (3 mL × 2). The deep
brown solution was filtered through a pad of Celite, which was
further washed with benzene (2 mL) until the washings were
colorless. The combined filtrate was evaporated to dryness in
vacuo to afford the product as a red solid; yield 188.2 mg
(100%). Crystals suitable for X-ray diffraction analysis were
grown by slow evaporation of a concentrated benzene solution
at room temperature. 1H NMR (C6D6, 500 MHz): δ 7.76-7.80
(m, 4, Ar), 7.23 (d, 2, Ar), 7.12-7.20 (m, 7, Ar), 7.07 (t, 1, Ar),
6.92 (m, 1, Ar), 6.65 (m, 1, Ar), 6.56 (t, 2, Ar), 6.32 (t, 1, Ar),
6.10 (dd, 1, Ar), 6.06 (d, 2, Ar), 2.17 (s, 6, CH3), 1.55 (d, 2, 3J HP
1
(CHMe2), 24.31 (CHMe2), 13.45 (d, J CP ) 23.6, PMe3).
Syn th esis of [iP r -NP ]Ni(η3-CH2P h ). Method 1: Solid {[iPr-
NP]NiCl}2 (500 mg, 0.47 mmol) was dissolved in THF (5 mL)
and cooled to -35 °C. To this was added dropwise a solution
of PhCH2MgCl (0.94 mL, 1.0 M Et2O solution, Aldrich, 0.94
mmol, 1 equiv per nickel). The reaction mixture was stirred
at room temperature overnight and evaporated to dryness. The
resulting residue was dissolved in CH2Cl2 (5 mL) and filtered
through a pad of Celite. All volatiles were removed in vacuo
to give a brownish red solid; yield 519 mg (94%). Method 2:
Solid [iPr-NP]NiCl(PMe3) (76.6 mg, 0.126 mmol) was dissolved
in THF (2 mL) and cooled to -35 °C. To this was added
dropwise a solution of PhCH2MgCl (0.13 mL, 1.0 M Et2O
solution, Aldrich, 0.13 mmol). The reaction mixture was stirred
at room temperature overnight and evaporated to dryness
under reduced pressure. The resulting residue was dissolved
in benzene (5 mL) and filterd through a pad of Celite. All
volatiles were removed in vacuo to give a brownish red solid;
yield 63.8 mg (86%). Method 3: A solid mixture of [iPr-NP]-
Li(THF)2 (200 mg, 0.341 mmol) and Ni(COD)2 (93.72 mg, 0.341
mmol) was dissolved in THF (6 mL) at room temperature. To
this was added a toluene solution of PhCH2Cl (3.41 mL, 0.1
M, 0.341 mmol) at room temperature. After being stirred at
room temperature for 3 h, the reaction mixture was evaporated
to dryness under reduced pressure. The reddish brown solid
residue was extracted with benzene (6 mL) and filtered
through a pad of Celite. Solvent was removed in vacuo to afford
the product as a brownish red solid; yield 178.5 mg (89%).
Crystals suitable for X-ray diffraction analysis were grown by
slow evaporation of a concentrated benzene solution at room
temperature. 1H NMR (C6D6, 500 MHz): δ 7.67 (m, 4, Ar), 7.22
(m, 3, Ar), 7.06 (m, 7, Ar), 6.85 (t, 1, Ar), 6.66 (t, 1, Ar), 6.57 (t,
2, Ar), 6.24 (t, 1, Ar), 6.14 (d, 2, Ar), 6.04 (t, 1, Ar), 3.46 (septet,
2, CHMe2), 1.56 (d, 2, 3J HP ) 4, NiCH2Ph), 1.12 (d, 12, CHMe2).
1H NMR (toluene-d8, 500 MHz): δ 7.64 (m, 4, Ar), 7.14 (m, 4,
Ar), 7.07 (m, 4, Ar), 7.00 (m, 2, Ar), 6.80 (t, 1, Ar), 6.63 (m, 1,
Ar), 6.55 (t, 2, Ar), 6.18 (t, 1, Ar), 6.11 (d, 2, Ar), 5.96 (t, 1, Ar),
3.41 (septet, 2, J ) 7.5, CHMe2), 1.52 (d, 2, 3J HP ) 3.5, NiCH2),
1.12 (d, 6, J ) 7.5, CHMe2), 1.09 (d, 6, J ) 7.5, CHMe2). 31P-
{1H} NMR (C6D6, 202.5 MHz): δ 36.24. 31P{1H} NMR (THF,
121.4 MHz): δ 36.27. 13C NMR (C6D6, 125.5 MHz): δ 168.11,
) 4, NiCH2Ph). 31P{1H} NMR (C6D6, 121.5 MHz): δ 34.84. 13
C
NMR (C6D6, 125.5 MHz): δ 166.67 (J CP ) 26.13), 151.91,
135.73, 134.63 (J CP ) 50.5), 134.06 (CH), 133.93 (CH), 133.49
(CH), 133.20 (J CP ) 11.75, CH), 130.57 (J CP ) 2.75, CH), 129.31
(J CP ) 10.75, CH), 128.68 (CH), 127.11 (J CP ) 2.63, CH), 123.42
(CH), 116.00, 114.69 (J CP ) 50.5), 112.50 (J CP ) 26.13, CH),
112.48 (J CP ) 8.13, CH), 110.60 (J CP ) 6.25, CH), 28.24 (2J CP
1
) 9.13, J CH ) 154, NiCH2Ph), 18.92 (1J CH ) 122, CH3). Anal.
Calcd for C33H30NNiP: C, 74.75; H, 5.70; N, 2.64. Found: C,
73.73; H, 5.87; N, 2.63.
Ack n ow led gm en t. We thank the National Science
Council of Taiwan for research support (NSC 90-2113-
M-110-024), Ms. Mei-Hui Huang for preparation of
H[Me-NP], Ms. Chao-Lien Ho for technical assistance
with NMR experiments, Ms. Chia-Chen Tsai for per-
forming combustion analysis, and Prof. Chen-Hsiung
Hung, Mr. Ting-Shen Kuo, Prof. Michael Y. Chiang, and
Ms. Hui-Chuan Yang for crystallographic assistance.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic data in CIF format for H[iPr-NP], [Me-NP]Li(THF)2,
[iPr-NP]NiCl(PMe3), [iPr-NP]NiMe(PMe3), [iPr-NP]NiPh(PMe3),
[iPr-NP]Ni(η3-CH2Ph), and [Me-NP]Ni(η3-CH2Ph). This mate-
rial is available free of charge via the Internet at http://
pubs.acs.org.
OM0498145