Synthesis and characterization of amido pincer complexes of lithium and nickel and catalysis of the nickel complexes in the Kumada cross-coupling

Article abstract of DOI:10.1021/om800580p

Reaction of N-benzylidene-2-(diphenylphosphino)benzenamine (2) with Ph ₂PLi yielded [Li(N{CH(Ph)-PPh₂}C₆H ₄(PPh₂)-2}] (3), and that with Ph₂PCH ₂Li·TMEDA generated [Li(N(CH(Ph)-C

Full text of DOI:10.1021/om800580p

Organometallics 2008, 27, 5649–5656
5649
Synthesis and Characterization of Amido Pincer Complexes of
Lithium and Nickel and Catalysis of the Nickel Complexes in the
Kumada Cross-Coupling
Kai Sun, Li Wang, and Zhong-Xia Wang*
Department of Chemistry, UniVersity of Science and Technology of China, Hefei, Anhui 230026, People’s
Republic of China
ReceiVed June 24, 2008
Reaction of N-benzylidene-2-(diphenylphosphino)benzenamine (2) with Ph2PLi yielded [Li{N{CH(Ph)-
PPh2}C6H4(PPh2)-2}] (3), and that with Ph2PCH2Li · TMEDA generated [Li{N{CH(Ph)-CH2PPh2}C6H4(PPh2)-
2}] (4). Treatment of 3 with (DME)NiCl2 gave [Ni(Cl){N{CH(Ph)PPh2}C6H4-(PPh2)-2}] (5). Reaction
of 4 with (Et3P)2NiCl2 afforded [Ni(Cl){N{CH(Ph)CH2PPh2}C6H4(PPh2)-2}] (6). N-(2-(Diphenylphos-
phino)benzylidene)-2-(diphenylphosphino)benzenamine reacted with LiMe to give [Li{N{CH(Me)C6H4-
(PPh2)-2}{C6H4(PPh2)-2}}] (8), which reacted with (Et3P)2NiCl2 to produce [Ni(Cl){N{CH(Me)C6H4-
(PPh2)-2}{C6H4(PPh2)-2}}] (9). 2 was converted to iminophosphoranes 2-{ArNdP(Ph2)}C6H4NdCHPh
(Ar ) p-MeC6H4, 10a; Ar ) 2,6-Pri2C6H3, 10b) by reaction with p-MeC6H4N3 and 2,6-Pri2C6H3N3,
respectively. 10a reacted with Ph2PLi and then (DME)NiCl2 to form [Ni(Cl){N{CH(Ph)PPh2}C6H4{P(Ph2)d
NC6H4Me-4}-2}] (11). The respective reaction of 10a and 10b with Ph2PCH2Li · TMEDA afforded
[Li{N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNAr}-2}] (Ar ) p-MeC6H4, 12a; Ar ) 2,6-Pri2C6H3, 12b).
Treatment of 12a and 12b, respectively, with (DME)NiCl2 yielded corresponding nickel complexes
[Ni(Cl){N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNAr}-2}] (Ar ) p-MeC6H4, 13a; Ar ) 2,6-Pri2C6H3, 13b).
Compounds 10a and 10b and the lithium complexes 3, 4, 8, 12a, and 12b were characterized by elemental
analyses and NMR spectroscopy. The diamagnetic nickel complexes 6, 9, 13a, and 13b were characterized
by elemental analyses, NMR spectroscopy, and mass spectra. The paramagnetic nickel complexes 5 and
11 were characterized by elemental analyses and mass spectra. The structures of compounds 2, 6, and
13a were further characterized by single-crystal X-ray diffraction techniques. Catalysis of the nickel
complexes in the Kumada cross-coupling was investigated. Complexes 5, 6, 11, and 13a exhibited high
catalytic activity, while complexes 9 and 13b showed relatively low catalytic activity.
reagents used in C-C coupling reactions are usually derived
from Grignard reagents,6 the Kumada reaction offers a more
direct approach to the desired products when the substrates
tolerate the background reactivity of a Grignard reagent.7 Some
new catalytic systems have been developed in recent years to
improve the activity of catalysts and extend the scope of
substrates.7,8 Recently we synthesized a new series of amido
pincer complexes of nickel (Chart 1) and proved that they could
efficiently catalyze the Kumada reaction.9 We hope to further
probe the structural effects on catalytic activity such as steric
Introduction
The search for appropriate ligands for effectively controlling
the stability and reactivity of metal complexes has been an
important topic of coordination and organometallic chemistry.
As a result, a range of new ligands have become available.
Recently amido pincer ligands have attracted considerable
attention.1-3 These ligands can stabilize main group and
transition metal ions. Some of the complexes with this type of
ligand displayed interesting reactivity, catalytic activity, or
photoluminescent properties.2-4 For example, the dinuclear
copper complex of [Bui-PNP]-, [Cu{Bui-PNP}]2, has been
found to be an exceptionally efficient luminophore that exhibits
both an exceptionally high quantum yield and a long lifetime;4
a rhodium complex of a bulky diarylamino-based PNP pincer
ligand is an efficient catalyst for the dimerization of terminal
alkynes and highly selective for the trans-enyne product.3c
Amido pincer complexes of group 10 metals are also able to
catalyze C-C cross-coupling such as Heck, Kumada, Suzuki,
and Negishi reactions.3h-n On the other hand, the Kumada
reaction, the first transition-metal-catalyzed cross-coupling reac-
tion, discovered in 1972,5 continues to attract considerable
attention. Because boronic acids and other organometallic
(2) (a) Peters, J. C.; Harkins, S. B.; Brown, S. D.; Day, M. W. Inorg.
Chem. 2001, 40, 5083–5091. (b) Harkins, S. B.; Peters, J. C. Inorg. Chem.
2006, 45, 4316–4318. (c) Storch, J.; Vojt´ısˇek, J. P.; C´ısarˇova, I. Inorg. Chim.
Acta 2004, 357, 4165–4171. (d) Edworthy, I. S.; Blake, A. J.; Wilson, C.;
Arnold, P. L. Organometallics 2007, 26, 3684–3689. (e) Choualeb, A.;
Lough, A. J.; Gusev, D. G. Organometallics 2007, 26, 5224–5229. (f) Liao,
C.-Y.; Chan, K.-T.; Zeng, J.-Y.; Hu, C.-H.; Tu, C.-Y.; Lee, H. M.
Organometallics 2007, 26, 1692–1702. (g) Ozerov, O. V.; Guo, C.; Papkov,
V. A.; Foxman, B. M. J. Am. Chem. Soc. 2004, 126, 4792–4793. (h) Posˇta,
ˇ
M.; Cerma´k, J.; Sy´kora, J.; Vojt´ısˇek, P.; C´ısaˇrova´, I.; Fajgar, R. J.
Organomet. Chem. 2008, 693, 1997–2003. (i) Ingleson, M. J.; Pink, M.;
Fan, H.; Caulton, K. G. J. Am. Chem. Soc. 2008, 130, 4262–4276. (j)
Giesbrecht, G. R.; Shafir, A.; Arnold, J. Chem. Commun. 2000, 2135–2136.
(k) Pitteri, B.; Marangoni, G.; Cattalini, L.; Visentin, F.; Bertolasi, V.; Gilli,
P. Polyhedron 2001, 20, 869–880. (l) Gatard, S.; Guo, C.; Foxman, B. M.;
Ozerov, O. V. Organometallics 2007, 26, 6066–6075. (m) DeMott, J. C.;
Guo, C.; Foxman, B. M.; Yandulov, D. V.; Ozerov, O. V. MendeleeV
Commun. 2007, 17, 63–65. (n) Lee, W.-Y.; Liang, L.-C. Dalton Trans.
2005, 1952–1956. (o) Fullmer, B. C.; Pink, M.; Fan, H.; Yang, X.; Baik,
M.-H.; Caulton, K. G. Inorg. Chem. 2008, 47, 3888–3892.
* To whom correspondence should be addressed. E-mail: zxwang@
ustc.edu.cn.
(1) (a) Liang, L.-C. Coord. Chem. ReV. 2006, 250, 1152–1177. (b)
Liddle, S. T.; Edworthy, I. S.; Arnold, P. L. Chem. Soc. ReV. 2007, 36,
1732–1744.
10.1021/om800580p CCC: $40.75
2008 American Chemical Society
Publication on Web 10/07/2008

5650 Organometallics, Vol. 27, No. 21, 2008
Sun et al.
Chart 1
Scheme 1
effects, chelate ring size, and ligand rigidity. Therefore we
designed several related ligands, prepared their nickel com-
plexes, and investigated the catalysis of the nickel complexes
in the Kumada reaction. Herein we report the results.
Results and Discussion
toluene, and three drops of HCOOH was stirred at room
temperature for 12 h to afford compound 2 in good yield. This
procedure required much less solvent and gave higher product
yield compared with the previous procedure. Reaction of 2 with
1 equiv of Ph2PLi gave the corresponding lithium complex 3,
while reaction with 1 equiv of Ph2PCH2Li · TMEDA generated
complex 4. Treatment of 3 with (DME)NiCl2 afforded the nickel
complex 5. Reaction of 4 with (Et3P)2NiCl2 produced the nickel
complex 6. Compound 2 is known and was characterized by
1H NMR spectroscopy and single-crystal X-ray diffraction. Its
ORTEP drawing is presented in Figure 1, along with selected
bond lengths and angles. In the molecule, the phenyl group on
the imine carbon atom is trans to the phenylene group on the
nitrogen atom. C(18)N(1)C(19)C(20) atoms are coplanar, but
the plane is not coplanar with the phenylene ring. The
N(1)-C(19) distance of 1.274(3) Å is indicative of a C-N
double bond. Complex 3 is a white solid, and complex 4 is
yellow solid. Both of them are soluble in THF and ether and
slightly soluble in hexane. They were characterized by 1H, 13C,
and 31P NMR spectroscopy and elemental analyses. The spectral
and analytical results showed no coordinated solvent molecules
or TMEDA in the complexes. However, recrystallization of 4
Synthesis and Characterization of Compounds 2-13b.
Synthesis of compounds 2-6 is summarized in Scheme 1.
Compound 2 was prepared by a modified literature procedure.10
Thus, a mixture of 1, PhCHO, activated 4 Å molecular sieves,
(3) (a) Choualeb, A.; Lough, A. J.; Gusev, D. G. Organometallics 2007,
26, 3509–3515. (b) Zhang, L.; Suzuki, T.; Luo, Y.; Nishiura, M.; Hou, Z.
Angew. Chem., Int. Ed. 2007, 46, 1909–1913. (c) Weng, W.; Guo, C.;
C¸ elenligil-C¸ etin, R.; Foxman, B. M.; Ozerov, O. V. Chem. Commun. 2006,
197–199. (d) Gatard, S.; C¸ elenligil-C¸ etin, R.; Guo, C.; Foxman, B. M.;
Ozerov, O. V. J. Am. Chem. Soc. 2006, 128, 2808–2809. (e) Harkins, S. B.;
Peters, J. C. Organometallics 2002, 21, 1753–1755. (f) Lian, B.; Thomas,
C. M., Jr.; Roisnel, T.; Carpentier, J.-F. Polyhedron 2007, 26, 3817–3824.
(g) Vicente, J.; Abad, J.-A.; Lo´pez-Serrano, J.; Jones, P. G.; Na´jera, C.;
Botella-Segura, L. Organometallics 2005, 24, 5044–5057. (h) Wei, W.; Qin,
Y.; Luo, M.; Xia, P.; Wong, M. S. Organometallics 2008, 27, 2268–2272.
(i) Huang, M.-H.; Liang, L.-C. Organometallics 2004, 23, 2813–2816. (j)
Zotto, A. D.; Zangrando, E.; Baratta, W.; Felluga, A.; Martinuzzi, P.; Rigo,
P. Eur. J. Inorg. Chem. 2005, 4707–4714. (k) Liang, L.-C.; Chien, P.-S.;
Lin, J.-M.; Huang, M.-H.; Huang, Y.-L.; Liao, J.-H. Organometallics 2006,
25, 1399–1411. (l) Fan, L.; Foxman, B. M.; Ozerov, O. V. Organometallics
2004, 23, 326–328. (m) Liang, L.-C.; Chien, P.-S.; Huang, M.-H. Orga-
nometallics 2005, 24, 353–357. (n) Wang, L.; Wang, Z.-X. Org. Lett. 2007,
9, 4335–4338. (o) Lian, B.; Thomas, C. M., Jr.; Lehmann, C. W.; Roisnel,
T.; Carpentier, J.-F. Inorg. Chem. 2007, 46, 328–340.
(4) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2005, 127, 2030–
2031.
1
from THF gave a THF adduct. The H NMR spectrum of 3
(5) (a) Tamao, K.; Sumitani, K.; Kumada, M. J. Am. Chem. Soc. 1972,
94, 4374–4376. (b) Corriu, R. J. P.; Masse, J. P. J. Chem. Soc., Chem.
Commun. 1972, 144.
(6) (a) de Meijere, A.; Diederich, F. Metal-Catalyzed Cross-Coupling
Reactions, 2nd ed.; Wiley-VCH: Weinheim, 2004. (b) Negishi, E. Handbook
of Organopalladium Chemistry for Organic Synthesis; Wiley: New York,
2002. (c) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457–2483. (d)
Davies, A. G. Organotin Chemistry, 2nd ed.; Wiley-VCH: Weinheim, 2004.
(e) Fang, G.-H.; Yan, Z.-J.; Yang, J.; Deng, M.-Z. Synthesis 2006, 1148–
1154.
(7) (a) Limmert, M. E.; Roy, A. H.; Hartwig, J. F. J. Org. Chem. 2005,
70, 9364–9370. (b) Organ, M. G.; Abdel-Hadi, M.; Avola, S.; Hadei, N.;
Nasielski, J.; O’Brien, C. J.; Valente, C. Chem.-Eur. J. 2007, 13, 150–
157.
displayed a CH signal at δ 5.35 ppm as a doublet and
corresponding phenyl and phenylene signals. The 31P NMR
spectrum gave two signals at δ -26.25 and 4.29 ppm,
respectively. The 1H NMR spectrum of 4 · THF exhibited THF,
CH, CH2, and aryl signals. Complex 5 is paramagnetic. This
may be caused by the existence of a small chelate ring, which
compels the central nickel atom to deviate from square-planar
geometry. Complex 5 was characterized by elemental analysis
and mass spectra. An electro-spray mass spectrum gave a [M
- Cl]+ fragment, and HR-MS gave a [M - Cl - Ph2P]+
fragment. Attempts to grow single crystals of complex 5 for
X-ray diffraction analysis were unsuccessful. The solution of
complex 5 in toluene was set aside for two months to form
traces of crystals. An X-ray diffraction study proved it to be
complex 5′. Complex 5′ may be formed through oxidation of 5
due to leakage of air after storing for a long period. Complex
5′ is monomeric in the solid state and crystallizes with two
molecules in the unit cell. An ORTEP structural drawing of a
single molecule is shown in Figure 2, along with selected bond
(8) (a) Park, S. Y.; Kang, M.; Yie, J. E.; Kim, J. M.; Lee, I.-M.
Tetrahedron Lett. 2005, 46, 2849–2852. (b) Huang, J.; Nolan, S. P. J. Am.
Chem. Soc. 1999, 121, 9889–9890. (c) Bohm, V. P. W.; Weskamp, T.;
Gstottmayr, C. W. K.; Herrmann, W. A. Angew. Chem., Int. Ed. 2000, 39,
1602–1604. (d) Li, G. Y.; Marshall, W. J. Organometallics 2002, 21, 590–
591. (e) Li, G. Y. Angew. Chem., Int. Ed. 2001, 40, 1513–1516. (f) Tasler,
S.; Lipshutz, B. H. J. Org. Chem. 2003, 68, 1190–1199. (g) Yoshikai, N.;
Mashima, H.; Nakamura, E. J. Am. Chem. Soc. 2005, 127, 17978–17979.
(h) Corbet, J.-P.; Mignani, G. Chem. ReV. 2006, 106, 2651–2710. (i)
Ackermann, L.; Gschrei, C. J.; Althammer, A.; Riederer, M. Chem.
Commun. 2006, 1419–1421. (j) Xi, Z.; Liu, B.; Chen, W. J. Org. Chem.
2008, 73, 3954–3957. (k) Fu¨rstner, A.; Leitner, A.; Me´ndez, M.; Krause,
H. J. Am. Chem. Soc. 2002, 124, 13856–13863.
(10) Doherty, S.; Knight, J. G.; Scanlan, T. H.; Elsegood, M. R. J.; Clegg,
W. J. Organomet. Chem. 2002, 650, 231–248.
(9) Wang, Z.-X.; Wang, L. Chem. Commun. 2007, 2423–2425.

Amido Pincer Complexes of Nickel and Kumada Reaction
Organometallics, Vol. 27, No. 21, 2008 5651
Figure 1. ORTEP drawing of 2 (30% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): N(1)-C(18) 1.428(2), N(1)-C(19)
1.274(3),C(19)-C(20)1.479(3),P(1)-C(13)1.850(2),C(18)-N(1)-C(19)
117.11(19), N(1)-C(19)-C(20) 119.7(2).
Figure 3. ORTEP drawing of 6 (30% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Ni(1)-N(1) 1.878(5), Ni(1)-Cl(1)
2.170(2), Ni(1)-P(1) 2.1729(19), Ni(1)-P(2) 2.1796(18), N(1)-C(1)
1.390(7),N(1)-C(7)1.464(7),C(7)-C(8)1.520(7),N(1)-Ni(1)-Cl(1)
179.49(16), N(1)-Ni(1)-P(1) 86.54(16), Cl(1)-Ni(1)-P(1) 93.26(8),
N(1)-Ni(1)-P(2)86.72(17),Cl(1)-Ni(1)-P(2)93.52(7),P(1)-Ni(1)-P(2)
171.65(8), C(1)-N(1)-C(7) 116.8(5), C(1)-N(1)-Ni(1) 120.9(4),
C(7)-N(1)-Ni(1) 121.6(4), N(1)-C(7)-C(8) 107.7(5).
Scheme 2. Synthesis of Complexes 8 and 9
Figure 2. ORTEP drawing of 5′ (30% thermal ellipsoids). Selected
bond lengths (Å) and angles (deg): Ni(1)-N(1) 1.893(5), Ni(1)-O(1)
1.925(4), Ni(1)-P(1) 2.1234(18), Ni(1)-Cl(1) 2.184(2), O(1)-P(2)
1.521(4), N(1)-Ni(1)-O(1) 89.9(2), N(1)-Ni(1)-P(1) 87.11(17),
O(1)-Ni(1)-P(1) 176.10(16), N(1)-Ni(1)-Cl(1) 177.92(18),
O(1)-Ni(1)-Cl(1) 92.00(15), P(1)-Ni(1)-Cl(1) 91.01(8).
geometry. N(1)-Ni(1)-Cl(1) is linear [179.49(16)°], while
P(1)-Ni(1)-P(2)isslightlybent[171.65(8)°].TheN(1)-Ni(1)-P(1)
angle [86.54(16)°] is almost the same as that of N(1)-Ni(1)-P(2)
[86.72(17)°], and both of them are narrower than those of
Cl(1)-Ni(1)-P(1) and Cl(1)-Ni(1)-P(2) [93.26(8)° and
93.52(7)°, respectively]. The Ni(1)-N(1) distance of 1.878(5)
Å is a little shorter than that of 5′. The Ni-P distances
[2.1729(19) and 2.1796(18) Å, respectively] are longer than that
in 5′, but within the normal range for P,N,P-chelate nickel
complexes.3k,9
lengths and angles. In the molecule the central nickel atom has
a distorted square-planar geometry. Both O(1)-Ni(1)-P(1)
[176.10(16)°] and N(1)-Ni(1)-Cl(1) [177.92(18)°] are ap-
proximately linear. The Ni-P distance of 2.1234(18) Å is a
little shorter than those in [R-PNP]NiR1 (R ) Ph, R1 ) Me,
Et, Bun, Bui, n-hexyl, CH2SiMe3, Ph; R ) Pri, R1 ) Me, Et,
Bun; R ) Cy, R1 ) Me, Et, Bun) [from 2.154(2) to 2.1966(9)
Å].3k The Ni-N distance of 1.893(5) Å is close to that of [Ph-
PNP]NiCl[1.895(3)Å],butshorterthanthosein[Ni(Cl){N[C(Ph)-
CHP(Pri)2dNAr]C6H4P(Ph)2-2}] and [Ni(Cl){N[C(Ph)CH-
P(Pri)2]C6H4[P(Ph)2dNAr]-2}] (Ar ) 2,6-Pri2C6H3) [1.955(3)
and 1.9386 Å, respectively].9
Synthesis of complexes 8 and 9 is summarized in Scheme 2.
Complex 8 was prepared by reaction of 7 with LiMe in THF.
Reaction of 8 with (Et3P)2NiCl2 afforded nickel complex 9 in
good yield. Complex 8 is a yellow solid and very soluble in
THF and soluble in Et2O. It gave a satisfactory elemental
analytical result. The 31P NMR spectrum exhibited two signals
1
at δ -23.60 and -22.24 ppm, respectively. The H and 13C
Complex 6 is green and very soluble in CH2Cl2 and soluble
in ether. It gave satisfactory elemental analysis. The HR-MS
displayed a molecular ion signal, and the fragmental mass
matches the calculated value very well. Complex 6 is diamag-
netic, and the 1H, 13C, and 31P NMR spectral data are consistent
with its structure. The structure of 6 was also further character-
ized by single-crystal X-ray diffraction. The ORTEP drawing
is presented in Figure 3, along with selected bond lengths and
angles. The skeletal structure of complex 6 is similar to that of
complex 5′, having a distorted square-planar coordination
NMR spectral data were also consistent with its structure.
Complex 9 is a brown powder and slightly soluble in THF and
toluene. It gave a satisfactory elemental analysis and 1H NMR,
31P NMR, and HR-MS spectral data.
Synthesis of compounds 10a-13b is summarized in Scheme
3. Both 10a and 10b were prepared by reaction of 2 with the
corresponding aryl azide in CH2Cl2 at room temperature.
Treatment of 10a with Ph2PLi and then (DME)NiCl2 gave nickel
complex 11. Reaction of 10a and 10b with Ph2PCH2Li ·
TMEDA afforded lithium complexes 12a and 12b, respectively.

5652 Organometallics, Vol. 27, No. 21, 2008
Scheme 3. Synthesis of Compounds 10a-13b
Sun et al.
Table 1. Evaluation of Complexes 5, 6, 9, 11, 13a, and 13b in the
Cross-Coupling Reactions of p-MeC6H4MgBr with p-MeOC6H4Ia
entry
complex (mol %)
yield (%)b
1
2
3
4
5
6
5 (0.005)
6 (0.01)
9 (0.01)
11 0.005)
13a (0.005)
13b (0.01)
98
89
43
97
96
48
a Reaction conditions: 1.0 equiv of p-MeOC6H4I, 1.3 equiv of
Grignard reagent, 2.5 mL of toluene, rt, 12 h. b Isolated yields.
Table 2. Catalytic Coupling of p-MeC6H4MgBr with p-RC6H4Cl by
Complexes 5-13ba
entry
R
complex (mol %)
yield (%)b
1
2
3
4
5
6
7
H
5 (2)
5 (2)
5 (4)
6 (2)
6 (2)
6 (4)
9 (2)
79
56
75
95
79
94
3
MeO
MeO
H
MeO
MeO
H
8
9
H
11 (2)
11 (2)
11 (4)
13a (2)
13a (2)
13a (4)
13b (2)
93
81
98
94
70
97
9
MeO
MeO
H
MeO
MeO
H
10
11
12
13
14
Treatment of 12a and 12b, respectively, with (DME)NiCl2
produced the corresponding nickel complexes 13a and 13b. Both
12a and 12b are air-sensitive yellow solids. Complex 12a was
washed with Et2O to form the diethyl ether adduct 12a · Et2O.
Complex 12b was recrystallized from Et2O to form 12b ·
1.5Et2O. Complex 13a is a green solid and was recrystallized
from Et2O to form 13a · 0.5Et2O. Complex 13b is a red solid.
It was recrystallized from toluene to give 13b · PhCH3. Each of
compounds 10a-13b gave satisfactory elemental analyses.
Compounds 10a, 10b, 12a, and 12b were charzcterized by 1H,
13C, and 31P NMR spectroscopy. Complex 11 is paramagnetic
and was characterized by an electro-spray mass spectrum, which
gave a [M - Cl]+ fragment at m/z 713. Both complexes 13a
a Reaction conditions: 1.0 equiv of aryl chloride, 1.3 equiv of
Grignard reagent, 2.5 mL of THF, rt, 36 h. b Isolated yields.
[Ni(Cl){N[C(Ph)CHP(Pri)2]C6H4[P(Ph)2dNAr]-2}] (Ar ) 2,6-
Pri2C6H3) [172.39(5)°],9 but smaller than that in complex 6. The
N(2)-Ni(1)-P(1) angle of 173.75(13)° is a little smaller than
that of [Ni(Cl){N[C(Ph)CHP(Pri)2]C6H4[P(Ph)2dNAr]-2}] (Ar
) 2,6-Pri2C6H3) [176.29(5)°], the latter being closer to a line.
The C(7)-N(1)-Ni(1)-P(1) atoms are approximately coplanar,
the torsion angle being 1.4°, while the C(8) atom is out of the
plane. The Ni(1)-N(1) distance of 1.923(4) Å is longer than
those in complex 6, [Pri-PNP]NiCl [1.9030(17) Å] and [Ph-
PNP]NiCl [1.895(3) Å],3k and shorter than that found in
[Ni(Cl){N[C(Ph)CHP(Pri)2]C6H4[P(Ph)2dNAr]-2}] (Ar ) 2,6-
Pri2C6H3) [1.9386(17) Å].9 The distance of the nickel atom to
the iminophosphorano-nitrogen atom [Ni(1)-N(2), 1.949(4) Å]
is longer than that to the formally negatively charged nitrogen
atom [Ni(1)-N(1), 1.923(4) Å]. Each of the phosphorus atoms
exhibits distorted tetrahedral geometry, and the N(2)-P(2)
distance of 1.591(4) Å is indicative of a P-N double bond.11
Catalysis of the Nickel Complexes in the Kumada
Cross-Coupling Reactions. We first evaluated the catalysis of
the nickel complexes in the cross-coupling reaction between
p-MeC6H4MgBr and p-MeOC6H4I. The results are listed in
Table 1. From the table, it can be found that complexes 5, 11,
and 13a were highly active, 0.005 mol % of complexes being
able to catalyze the reaction to completion. Complexes 9 and
13b displayed relatively low catalytic activity. Complex 6
showed lower catalytic activity than complexes 5, 11, and 13a,
but higher activity than complexes 9 and 13b. Then we tested
the catalysis of the nickel complexes in the cross-coupling
reaction of p-MeC6H4MgBr with aryl chlorides. The reactions
were carried out in THF at room temperature, and the results
are listed in Table 2. Complexes 6, 11, and 13a exhibited high
catalytic activity. Two mol % of catalysts can drive the reaction
of p-MeC6H4MgBr with PhCl to completion. If deactivated aryl
1
and 13b are diamagnetic and were characterized by H, 13C,
and 31P NMR spectroscopy and HR-MS, which exhibited
molecular ion signals. The structure of complex 13a was
additionally characterized by single-crystal X-ray diffraction.
The ORTEP drawing is presented in Figure 4, along with
selected bond lengths and angles. In the molecule of 13a the
central nickel atom has a distorted square-planar geometry. The
N(1)-Ni(1)-Cl(1) angle of 171.39(13)° is close to that in
Figure 4. ORTEP drawing of 13a (30% thermal ellipsoids).
Selected bond lengths (Å) and angles (deg): Ni(1)-N(1) 1.923(4),
Ni(1)-N(2)1.949(4),Ni(1)-P(1)2.1160(15),Ni(1)-Cl(1)2.1812(14),
C(7)-C(8) 1.515(7), P(1)-C(7) 1.805(5), N(2)-P(2) 1.591(4),
N(1)-Ni(1)-N(2)96.54(17),N(1)-Ni(1)-P(1)87.20(12),N(2)-Ni(1)-P(1)
173.75(13), N(1)-Ni(1)-Cl(1) 171.39(13), N(2)-Ni(1)-Cl(1)
91.75(12), P(1)-Ni(1)-Cl(1) 84.34(6), P(2)-N(2)-Ni(1) 106.82(19),
C(7)-P(1)-Ni(1)102.70(17),C(1)-N(1)-Ni(1)127.6(3),C(8)-N(1)-Ni(1)
115.9(3).
(11) Corbridge, D. E. C. Phosphorus; Elsevier: Amsterdam, 1985; p
38.

Amido Pincer Complexes of Nickel and Kumada Reaction
Organometallics, Vol. 27, No. 21, 2008 5653
2-(diphenylphosphino)benzenamine19 were prepared according to
the reported methods. All other chemicals were obtained from
commercial vendors and used as received. NMR spectra were
recorded on a Bruker av300 spectrometer at ambient temperature.
The chemical shifts of the 1H and 13C NMR spectra were referenced
to TMS or internal solvent resonances. MS data were recorded on
an Agilent6890/Micromass GCT-MS spectrometer (EI) or Thermo
Finnigan LCQ Advantage Max ion trap mass spectrometer (ESI).
Elemental analysis was performed by the Analytical Center of the
University of Science and Technology of China.
Synthesis of Compounds 2-6 and 8-13b. 2-Ph2PC6H4Nd
CHPh (2). In a three-necked flask was added activated 4 Å
molecular sieves (30 g), toluene (40 mL), 2-(diphenylphosphi-
no)benzenamine (13.85 g, 0.05 mol), and PhCHO (10.6 g, 0.1 mol).
Then three drops of HCOOH was added. The mixture was stirred
at room temperature for 12 h and then filtered. The molecular sieves
were washed with toluene (3 × 20 mL). The combined organic
layers were washed with water and then dried over Na2SO4. Na2SO4
was removed by filtration, and volatiles were removed from the
filtrate by rotary evaporation. MeOH was added to the residue to
form a yellowish solid (14.5 g, 79.4%), mp 108-110 °C. 1H NMR
(CDCl3): δ 6.82-6.86 (m, 1H, Ar), 7.00-7.04 (m, 1H, Ar), 7.12
(t, J ) 7.4 Hz, 1H, Ar), 7.24-7.39 (m, 14H, Ar), 7.63-7.67 (m,
2H, Ar), 8.13 (s, 1H, CH).
chloride, p-MeOC6H4Cl, was employed as electrophilic sub-
strate, 4 mol % of catalysts was necessary to complete the
reactions (entries 6, 10, and 13, Table 2). Complex 5 showed
lower activity than 6, 11, and 13 (entries 1-3, Table 1), 4 mol
% of catalyst leading to 75% of cross-coupling product in the
reaction of p-MeC6H4MgBr with p-MeOC6H4Cl under the same
conditions mentioned above. Compared with complexes 5 and
6, complex 9 exhibited much lower catalytic activity. Thus, in
the P,N,P-chelate nickel complexes, the complex with two fused
five-membered rings showed higher catalytic activity, while the
complex with five- and six-membered chelate rings displayed
lower catalytic activity. It seems that the larger chelate ring in
complex 9 leads to its low activity. The N,N,P-chelate com-
plexes 11 and 13a displayed similar catalytic activity to complex
6 and better than complex 5. Complex 13b showed very low
catalytic activity. This is attributed to steric effects of the ligand.
A similar result was observed in the catalytic systems we
previously reported.9 It is also noticed that complex 13a has
similar catalytic activity to complex C (Ar ) o-MeC6H4), while
complex 6 is a little more active than complex A (R ) Ph),
which showed relatively low catalytic activity in the reaction
of p-MeC6H4MgBr with p-MeOC6H4Cl.9
[Li{N{CH(Ph)PPh2}C6H4(PPh2)-2}] (3). Compound 2 (0.913
g, 2.5 mmol) was dissolved in THF (10 mL) and cooled to about
-80 °C. To the solution was added a THF solution of Ph2PLi
[prepared in situ from Ph2PH (0.465 g, 2.5 mmol) and LiBun (1
mL, 2.5 M solution in hexane, 2.5 mmol) in THF (6 mL)] with
stirring. The mixture was warmed to room temperature and stirred
for 12 h. Solvents were removed in vacuo, and the residue was
dissolved in Et2O and then filtered. The filtrate was concentrated
in vacuo and kept at 0 °C overnight to afford a white solid of 3
(1.25 g, 89.8%), mp 136-138 °C. Anal. Calcd for C37H30NP2Li:
Summary
We have synthesized and characterized a series of lithium
and nickel complexes supported by unsymmetrical amido pincer
ligands. Single-crystal X-ray diffraction results showed that the
central metal atoms of complexes 5′, 6, and 13a have distorted
square-planar geometries. The diamagnetic 9 and 13b are
expected to have similar coordination geometries. However, the
central nickel atoms of paramagnetic 5 and 11 may markedly
deviate from square-planar geometries. Complexes 5, 6, 11, and
13a can efficiently catalyze cross-coupling reactions of
p-MeC6H4MgBr with aryl halides, including unactivated and
deactivated aryl chlorides, while 9 and 13b exhibited low
catalytic activity. The approximate activity order in catalytic
cross-coupling of p-MeC6H4MgBr with aryl chlorides is 6 =
11 g 13a > 5 > 13b > 9.
1
C, 79.71; H, 5.42; N, 2.51. Found: C, 79.38; H, 5.63; N, 2.61. H
NMR (C6D6): δ 5.35 (d, J ) 7 Hz, 1H, CH), 5.88-5.95 (m, 1H,
Ar), 6.52 (t, J ) 7.1 Hz, 1H, Ar), 6.62-6.67 (m, 1H, Ar), 6.90-7.05
(m, 19H, Ar), 7.23-7.40 (m, 7H, Ar). 13C NMR (C6D6): δ 65.9,
112.0, 118.3, 120.3, 127.0 (d, J ) 2.6 Hz), 127.9, 128.5, 128.6,
128.71, 128.74, 128.8, 128.83, 128.86, 128.9, 129.0, 129.3, 131.1,
133.7, 134.0, 134.1, 134.2, 134.3, 134.5, 134.5, 134.8, 135.0, 136.0,
136.1, 136.3, 136.4, 140.6, 140.8, 150.2 (d, J ) 4.3 Hz), 150.5 (d,
J ) 4.2 Hz). 31P NMR (C6D6): δ -26.25, 4.29.
Experimental Section
[Li{N{CH(Ph)CH2PPh2}C6H4(PPh2)-2}] (4). Compound 2 (0.913
g, 2.5 mmol) was dissolved in THF (10 mL) and cooled to about
-80 °C. To the solution was added a solution of Ph2PCH2Li ·
TMEDA (0.805 g, 2.5 mmol) in THF (6 mL) with stirring. The
mixture was warmed to room temperature and stirred for 12 h.
Volatiles were removed in vacuo, and the residue was dissolved in
Et2O and then filtered. The filtrate was concentrated in vacuo and
kept at 0 °C overnight to give a yellow solid of 4 (1.32 g, 92.4%),
mp 158-160 °C. Anal. Calcd for C38H32NP2Li: C, 79.85; H, 5.64;
N, 2.45. Found: C, 79.49; H, 5.93; N, 2.75. An NMR spectral
analytical sample was recrystallized from THF and gave an adduct
of THF (4 · THF). 1H NMR (C6D6): δ 1.21-1.26 (m, THF),
2.40-2.46 (m, 1H, CH2), 2.80-2.86 (m, 1H, CH2), 3.42-3.47 (m,
THF), 4.49 (dd, J ) 6.4 Hz, 1H, CH), 6.24-6.32 (m, 2H, Ar),
6.93 (t, J ) 6.9 Hz, 1H, Ar), 7.01-7.03 (m, 4H, Ar), 7.06-7.21
(m, 12H, Ar), 7.33-7.37 (m, 4H, Ar), 7.49 (t, J ) 6.9 Hz, 2H,
General Procedures. All air- or moisture-sensitive manipulations
were performed under dry nitrogen using standard Schlenk tech-
niques. Solvents were distilled under nitrogen over sodium (toluene),
sodium/benzophenone (n-hexane, THF, and diethyl ether), or CaH2
(CH2Cl2) and degassed prior to use. LiBun and LiMe were
purchased from Acros Organics and used as received. CDCl3 and
C6D6 were purchased from Cambridge Isotope Laboratories, Inc.,
and C6D6 was degassed and stored over Na/K alloy (C6D6) or 4 Å
molecular sieves (CDCl3). ArN3,12 PEt3,13 Ph2PCH2Li · TMEDA,14
p-MeC6H4MgBr,15 (DME)NiCl2,16 (Et3P)2NiCl2,17 2-(diphenylphos-
phino)benzenamine18 and N-(2-(diphenylphosphino)benzylidene)-
(12) Fusco, R.; Garanti, L.; Zecchi, G. J. Org. Chem. 1975, 40, 1906–
1909.
(13) Hewitt, F.; Holliday, A. K. J. Chem. Soc. 1953, 530–534.
(14) Schore, N. E.; Benner, L. S.; La Belle, B. E. Inorg. Chem. 1981,
20, 3200–3208.
(15) Elson, L. F.; McKillop, A.; Taylor, E. C. Org. Synth. 1976, 55,
48–51.
Ar), 7.57 (t, J ) 6.7 Hz, 2H, Ar), 7.70 (t, J ) 7.5 Hz, 2H, Ar). 13
C
NMR (C6D6): δ 25.5, 39.9, 60.4 (d, J ) 11.8 Hz), 68.4, 109.2,
111.7, 126.1, 128.0, 128.47, 128.53, 128.6, 128.9, 132.0, 133.3,
(16) Ward, L. G. L. Inorg. Synth. 1971, 13, 154–164.
(17) Stanger, A.; Vollhardt, K. P. C. Organometallics 1992, 11, 317–
320.
(18) Cooper, M. K.; Downes, J. M.; Duckworth, P. A. Inorg. Synth.
1989, 25, 129–133.
(19) Ainscough, E. W.; Brodie, A. M.; Buckley, P. D.; Burrell, A. K.;
Kennedy, S. M. F.; Waters, J. M. J. Chem. Soc., Dalton Trans. 2000, 2663–
2671.

5654 Organometallics, Vol. 27, No. 21, 2008
Sun et al.
133.4, 133.55, 133.63, 134.1, 134.2, 134.4, 134.5, 134.6, 138.2 (d,
J ) 3.3 Hz), 138.5, 139.7 (d, J ) 9.4 Hz), 150.5 (d, J ) 3.4 Hz),
163.8, 164.0. 31P NMR (C6D6): δ -26.98, -16.11.
C38H32NP2NiCl: C, 69.28; H, 4.90; N, 2.13. Found: C, 68.99; H,
4.77; N, 2.11. 1H NMR (CDCl3): δ 1.75 (d, J ) 6.6 Hz, 3H, CH3),
4.03 (q, J ) 6.9 Hz, 1H, CH), 6.21 (t, J ) 7.2 Hz, 1H, Ar),
6.53-6.58 (m, 1H, Ar), 7.01 (t, J ) 8.1 Hz, 2H, Ar), 7.22-7.49
(m, 16H, Ar), 7.72-7.82 (m, 8H, Ar). 31P NMR (CDCl3): δ -17.30
(d, J ) 363.7 Hz), 20.66 (d, J ) 362.1 Hz). HR-MS (EI): m/z
657.1060 [M]+, calcd 657.1052.
[Ni(Cl){N{CH(Ph)PPh2}C6H4(PPh2)-2}] (5). To a solution of
(DME)NiCl2 (0.274 g, 1.25 mmol) in THF (10 mL) was added a
solution of 3 (0.696 g, 1.25 mmol) in THF (10 mL) at about -80
°C. The mixture was warmed to room temperature and stirred
overnight. Volatiles were removed in vacuo, and the residue was
dissolved in CH2Cl2. The solution was filtered and the filtrate was
concentrated to afford a brown solid identified as 5 · 0.5CH2Cl2 (0.66
g, 77%), mp 155-157 °C. Anal. Calcd for C37H30NP2NiCl ·
0.5CH2Cl2: C, 65.54; H, 4.55; N, 2.04. Found: C, 65.57; H, 4.87;
N, 2.32. HR-MS (EI): m/z 423.0663 [M - Cl - 2Ph - P]+, calcd
423.0687. ESI-MS: m/z 608 [M - Cl]+.
2-{p-MeC6H4NdP(Ph2)}C6H4NdCHPh (10a). To a stirred
solution of 2 (1.83 g, 5.01 mmol) in CH2Cl2 (15 mL) was added
dropwise p-MeC6H4N3 (0.82 g, 6.15 mmol). The mixture was stirred
at room temperature for 2 h. Solvent was removed in vacuo, and
the residue was washed with hexane to afford a yellow powder
(2.2 g, 93.3%), mp 128-130 °C. Anal. Calcd for C32H27N2P: C,
81.68; H, 5.78; N, 5.95. Found: C, 81.60; H, 5.75; N, 5.99. 1H
NMR (CDCl3): δ 2.15 (s, 3H, CH3), 6.56 (d, J ) 7.8 Hz, 2H, Ar),
6.71 (d, J ) 8.1 Hz, 2H, Ar), 6.94 (dd, J ) 4.5, 7.2 Hz, 1H, Ar),
7.18-7.21 (m, 2H, Ar), 7.25-7.34 (m, 10H, Ar), 7.53-7.58 (m,
1H, Ar), 7.80 (s, 1H, CH), 7.85-7.97 (m, 5H, Ar). 13C NMR
(CDCl3): δ 20.6, 118.7 (d, J ) 7.5 Hz), 123.4 (d, J ) 16.6 Hz),
123.9, 125.1, 125.7 (d, J ) 11.2 Hz), 126.0, 128.1, 128.3 (d, J )
3.3 Hz), 129.1, 129.2, 131.0 (d, J ) 2.9 Hz), 131.4, 131.5, 132.6
(d, J ) 9.8 Hz), 132.8, 133.4 (d, J ) 2.4 Hz), 135.1 (d, J ) 8.3
[Ni(Cl){N{CH(Ph)CH2PPh2}C6H4(PPh2)-2}] (6). To a solution
of (Et3P)2NiCl2 (0.458 g, 1.25 mmol) in THF (10 mL) was added
a solution of 4 (0.714 g, 1.25 mmol) in THF (10 mL) at about
-80 °C. The mixture was warmed to room temperature and stirred
overnight. Volatiles were removed in vacuo, and the residue was
dissolved in Et2O. The solution was filtered and the filtrate was
concentrated to form green crystals of 6 (0.658 g, 80%), mp
195-197 °C. Anal. Calcd for C38H32NP2NiCl: C, 69.28; H, 4.90;
Hz), 135.9, 149.0 (d, J ) 2.6 Hz), 154.4 (d, J ) 5 Hz), 160.2. 31
NMR (CDCl3): δ -0.09.
P
1
N, 2.13. Found: C, 69.42; H, 4.77; N, 2.17. H NMR (CDCl3): δ
2.72-2.90 (m, 2H, CH2), 4.81 (dd, J ) 6.7, 38.2 Hz, CH), 6.13
(dd, J ) 5.7, 8.4 Hz, 1H, Ar), 6.20 (t, J ) 6.9 Hz, 1H, Ar),
6.76-6.82 (m, 1H, Ar), 6.87-6.90 (m, 3H, Ar), 6.98-7.06 (m,
3H, Ar), 7.14-7.20 (m, 1H, Ar), 7.28-7.31 (m, 4H, Ar), 7.37-7.44
(m, 9H, Ar), 7.66-7.70 (m, 2H, Ar), 7.79-7.85 (m, 2H, Ar),
7.89-7.95 (m, 2H, Ar). 13C NMR (CDCl3): δ 40.6 (d, J ) 23
Hz), 64.1-64.2 (m), 113.9 (d, J ) 6.6 Hz), 114.7, 114.9, 117.2,
117.8, 125.5, 126.7, 126.8, 128.2, 128.23, 128.3, 128.4, 128.7 (d,
J ) 1.1 Hz), 128.74, 128.8 (d, J ) 1.5 Hz), 128.9, 129.2, 130.2 (d,
J ) 2.5 Hz), 130.5 (d, J ) 2.6 Hz), 130.6 (d, J ) 2.5 Hz), 130.7
(d, J ) 2.6 Hz), 132.9, 133.1, 133.2 (d, J ) 1.8 Hz), 133.5 (d, J )
1.4 Hz), 133.7 (d, J ) 1.4 Hz), 133.8, 133.9 (d, J ) 1.6 Hz), 134.0
(d, J ) 1.6 Hz), 138.0, 143.5 (d, J ) 2.4 Hz), 166.1 (d, J ) 4.2
Hz), 166.5 (d, J ) 4.4 Hz). 31P NMR (CDCl3): δ 19.95 (d, J )
335.8 Hz), 28.71 (dm, J ) 330.7 Hz). HR-MS (EI): m/z 657.1044
[M]+, calcd 657.1052.
2-{2,6-Pri2C6H3NdP(Ph2)}C6H4NdCHPh (10b). Compound
10b was prepared according to a similar procedure to that of 10a.
To a stirred solution of 2 (0.516 g, 1.41 mmol) in CH2Cl2 (10 mL)
was added dropwise 2,6-Pri2C6H3N3 (0.31 g, 1.52 mmol). The
mixture was stirred at room temperature for 12 h. Solvent was
removed in vacuo. The oily residue was dissolved in Et2O and then
filtered. The filtrate was concentrated to produce yellow crystals
(0.55 g, 72%), mp 135-137 °C. Anal. Calcd for C37H37N2P: C,
82.19; H, 6.90; N, 5.18. Found: C, 82.01; H, 6.83; N, 5.26. 1H
NMR (CDCl3): δ 0.67 (d, J ) 6.8 Hz, 12H, CH3), 2.97-3.11 (m,
2H, Pri), 6.59-6.65 (m, 1H, Ar), 6.75 (d, J ) 6.9 Hz, 2H, Ar),
6.78-6.83 (m, 1H, Ar), 7.10-7.31 (m, 12H, Ar), 7.47 (t, J ) 7.5
Hz, 1H, Ar), 7.53-7.59 (m, 4H, Ar), 7.67 (s, 1H, CH), 7.87-7.94
(m, 1H, Ar). 13C NMR (CDCl3): δ 23.5, 28.6, 118.5 (d, J ) 2.9
Hz), 118.7 (d, J ) 8.1 Hz), 120.1, 122.5, 125.5, 125.6, 127.9 (d, J
) 12.3 Hz), 128.3, 129.3, 130.5 (d, J ) 2.8 Hz), 131.4, 132.2 (d,
J ) 9.7 Hz), 133.1, 133.2, 134.6, 134.7, 136.0, 142.6 (d, J ) 6.7
Hz), 145.1, 159.7. 31P NMR (CDCl3): δ -11.93.
[Li{N{CH(Me)C6H4(PPh2)-2}{C6H4(PPh2)-2}}] (8). To a stirred
solution of 7 (0.25 g, 0.455 mmol) in THF (8 mL) was added
dropwise LiMe (0.29 mL, a 1.6 M solution in Et2O, 0.464 mmol)
at about -80 °C. The mixture was warmed to room temperature
and stirred overnight. Volatiles were removed in vacuo, and the
residue was washed with hexane and then dissolved in Et2O. The
solution was filtered and the filtrate was concentrated to yield a
yellow solid of 8 (0.22 g, 84.6%), mp 177-179 °C. Anal. Calcd
for C38H32NP2Li: C, 79.85; H, 5.64; N, 2.45. Found: C, 79.55; H,
[Ni(Cl){N{CH(Ph)PPh2}C6H4{P(Ph2)dNC6H4Me-4}-2}] (11).
Compound 10a (0.49 g, 1.04 mmol) was dissolved in THF (5 mL)
and cooled to about -80 °C. To the solution was added a THF
solution of Ph2PLi [prepared in situ from Ph2PH (0.195 g, 1.05
mmol) and LiBun (0.42 mL, 2.5 M solution in hexane, 1.05 mmol)
in THF (5 mL)] with stirring. The mixture was warmed to room
temperature and stirred for 12 h. The formed solution was added
to a stirred solution of (DME)NiCl2 (0.231 g, 1.05 mmol) in THF
(10 mL) at about -80 °C. The mixture was warmed to room
temperature and stirred overnight. Volatiles were removed in vacuo,
and the residue was dissolved in CH2Cl2. The solution was filtered
and the filtrate was concentrated to afford a brown solid. The solid
was washed with toluene to give a brown powder of 11 · PhCH3
(0.73 g, 85.2%), mp 111-113 °C. Anal. Calcd for
C44H37N2P2NiCl · PhCH3: C, 72.75; H, 5.39; N, 3.33. Found: C,
72.66; H, 5.62; N, 3.25. ESI-MS: m/z 713 [M - Cl]+.
1
5.69; N, 2.49. H NMR (C6D6): δ 1.28 (d, J ) 6.3 Hz, 3H, CH3),
5.54 (t, J ) 6 Hz, 1H, Ar), 5.73 (q, J ) 6.3 Hz, 1H, CH), 6.64 (t,
J ) 7.5 Hz, 1H, Ar), 6.72-6.76 (m, 1H, Ar), 6.97 (t, J ) 6.6 Hz,
1H, Ar), 6.99-7.27 (m, 16H, Ar), 7.38-7.45 (m, 3H, Ar),
7.51-7.61 (m, 5H, Ar). 13C NMR (C6D6): δ 24.6, 51.1, 112.6 (d,
J ) 2.4 Hz), 112.7 (d, J ) 2.3 Hz), 117.76 (d, J ) 3.7 Hz), 118.9,
119.1, 125.6 (d, J ) 5.6 Hz), 127.4, 127.9, 128.2, 128.8, 128.85,
128.9, 128.94, 128.99, 129.04, 130.2, 131.2, 134.0 (d, J ) 5.5 Hz),
134.2, 134.3 (d, J ) 2.4 Hz), 134.38, 134.41, 134.6, 134.7, 134.9,
135.2 (d, J ) 6.8 Hz), 136.4 (d, J ) 2 Hz), 136.5 (d, J ) 2.2 Hz),
137.1, 137.2 (d, J ) 2.6 Hz), 137.3, 150.2, 150.5, 150.6, 150.9.
31P NMR (C6D6): δ -23.60, -22.24.
[Li{N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNC6H4Me-4}-2}] (12a).
Compound 10a (0.289 g, 0.61 mmol) was dissolved in THF (5
mL) and cooled to about -80 °C. To the solution was added a
solution of Ph2PCH2Li · TMEDA (0.198 g, 0.61 mmol) in THF (5
mL) with stirring. The mixture was warmed to room temperature
and stirred for 12 h. Volatiles were removed in vacuo, and the
residue was washed successively with hexane and Et2O to give a
yellow powder of 12a · Et2O (0.365 g, 79.1%), mp 186-188 °C.
Anal. Calcd for C45H39N2P2Li · Et2O: C, 78.36; H, 6.58; N, 3.73.
[Ni(Cl){N{CH(Me)C6H4(PPh2)-2}{C6H4(PPh2)-2}}] (9). To a
solution of (Et3P)2NiCl2 (0.457 g, 1.25 mmol) in THF (10 mL)
was added a solution of 8 (0.714 g, 1.25 mmol) in THF (10 mL)
at about -80 °C. The mixture was warmed to room temperature
and stirred overnight. Red-brown precipitates were formed. The
mixture was filtered and the solid was washed with THF to give
complex 9 (0.67 g, 81.4%), mp 263-264 °C. Anal. Calcd for

Amido Pincer Complexes of Nickel and Kumada Reaction
Organometallics, Vol. 27, No. 21, 2008 5655
Table 3. Details of the X-ray Structure Determinations of Complexes 2, 5′, 6, and 13a
2
5′ · 0.5C7H8
6 · 0.5CH2Cl2
13a · C7H8
formula
fw
C25H20NP
365.39
C81H68Cl2N2Ni2O2P4
1413.57
C
38.5H33Cl2N NiP2
C52H47ClN2NiP2
856.02
701.21
temp, K
294(2)
298(2)
298(2)
298(2)
cryst syst
space group
monoclinic
P1c1
monoclinic
P21
monoclinic
P21/c
monoclinic
P21/c
a, Å
b, Å
c, Å
15.108(3)
13.258(3)
20.346(4)
98.395(3)
4031.6(15)
8
15.922(2)
9.7547(16)
23.679(3)
107.689(2)
3503.8(8)
2
14.647(2)
17.098(3)
15.666(3)
115.807(2)
3532.1(9)
4
15.2015(15)
18.635(2)
16.855(2)
113.301(2)
4385.3(9)
4
ꢀ, deg
V, Å3
Z
Dcalcd, g cm-3
1.204
1.340
1.319
1.297
F(000)
1536
0.145
1.54 to 25.00
30 031
1468
0.754
1.34 to 25.01
17 717
1452
0.819
1.87 to 25.00
17 296
1792
0.614
1.46 to 25.01
17 873
µ, mm-1
θ range for data collecn, deg
no. of reflns collected
no. of indep reflns (Rint
)
11 604 (Rint ) 0.0401)
11 604/26/974
1.041
R1 ) 0.0566
wR2 ) 0.1321
R1 ) 0.1092
wR2 ) 0.1658
0.211 and -0.195
11 859 (Rint ) 0.0572)
11 859/1/838
0.816
R1 ) 0.0561
wR2 ) 0.0619
R1 ) 0.1313
wR2 ) 0.0748
0.632 and -0.366
6140 (Rint ) 0.0905)
6140/86/415
1.002
R1 ) 0.0620
wR2 ) 0.1019
R1 ) 0.1607
wR2 ) 0.1173
0.590 and -0.412
7701 (Rint ) 0.0769)
7701/120/523
1.061
R1 ) 0.0673
wR2 ) 0.1177
R1 ) 0.1387
wR2 ) 0.1430
0.752 and -0.457
no. of data/ restraints/params
goodness of fit on F2
final R indicesa [I > 2σ(I)]
R indices (all data)
largest diff peak and hole, e Å-3
a R1 ) ∑|Fo| - |Fc||/∑|Fo|; wR2 ) [∑w(Fo - Fc ) /∑w(Fo4)]1/2
.
2
2 2
Found: C, 78.49; H, 6.63; N, 3.46. 1H NMR (C6D6): δ 1.16 (t, J )
6.9 Hz, 6H, Et2O), 2.25 (s, 3H, CH3), 2.34 (t, J ) 11.7 Hz, 1H,
CH2), 2.55-2.69 (m, 1H, CH2), 3.36 (q, J ) 6.9 Hz, 4H, Et2O),
4.64-4.74 (m, 1H, CH), 6.16 (b, 1H, Ar), 6.39 (t, J ) 6.9 Hz, 1H,
Ar), 6.79-6.80 (m, 1H, Ar), 6.99-7.29 (m, 22H, Ar), 7.40 (s, 2H,
Ar), 7.53-7.59 (m, 2H, Ar), 7.93-8.06 (m, 4H, Ar). 13C NMR
(C6D6): δ 15.4, 20.7, 43.4, 60.4 (d, J ) 8.8 Hz), 65.8, 107.2 (d, J
) 15.9 Hz), 115.2 (d, J ) 8.9 Hz), 123.1 (d, J ) 18.2 Hz), 125.9,
127.2, 127.9, 128.2, 128.5, 128.6, 128.7, 128.8 (d, J ) 3.2 Hz),
128.85, 128.9, 129.0, 130.0, 133.1, 133.3, 133.4, 133.6, 133.7,
133.8, 134.1, 134.2, 149.6, 149.8. 31P NMR (C6D6): δ -23.14,
14.44.
dryness. The residual solid was dissolved in Et2O and then
concentrated to give green crystals of 13a · 0.5Et2O (0.323 g,
74.5%), mp 142-144 °C. Anal. Calcd for C45H39N2P2NiCl ·
0.5Et2O: C, 70.48; H, 5.54; N, 3.50. Found: C, 70.23; H, 5.45; N,
3.31. 1H NMR (CDCl3): δ 1.13-1.27 (m, 3H, Et2O), 2.28 (s, 3H,
CH3), 2.30 (b, 2H, CH2), 3.41-3.54 (m, 2H, Et2O), 4.70 (b, 1H,
CH), 6.08-6.22 (m, 1H, Ar), 6.33-6.47 (m, 1H, Ar), 6.63-6.87
(m, 3H, Ar), 7.00-7.30 (m, 16H, Ar), 7.40-7.60 (m, 7H, Ar),
7.64-7.82 (m, 3H, Ar), 8.16-8.30 (m, 2H, Ar). 13C NMR (CDCl3):
δ 15.4, 20.9, 38.8, 59.0, 66.0, 106.9, 127.4, 127.9, 128.1, 128.4,
128.6, 128.8, 129.0, 129.9, 130.1, 133.0, 133.4, 134.2, 134.5, 134.8,
147.8. 31P NMR (CDCl3): δ -27.65, 24.87. HR-MS (EI): m/z
762.1628 [M]+, calcd 762.1631.
[Li{N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNC6H3Pri2-2,6}-2}] (12b).
Compound 10b (1.206 g, 2.23 mmol) was dissolved in THF (10
mL) and cooled to about -80 °C. To the solution was added a
solution of Ph2PCH2Li · TMEDA (0.73 g, 2.26 mmol) in THF (10
mL) with stirring. The mixture was stirred at room temperature
for 1 h and then at 60 °C overnight. Volatiles were removed in
vacuo, and the residue was dissolved in Et2O. The solution was
filtered and the filtrate was concentrated to afford a yellow solid
of 12b · 1.5Et2O (1.25 g, 65.3%), mp 189-191 °C. Anal. Calcd
for C50H49N2P2Li · 1.5Et2O: C, 78.37; H, 7.52; N, 3.27. Found: C,
[Ni(Cl){N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNC6H3Pri2-2,6}-
2}] (13b). To a solution of (DME)NiCl2 (0.286 g, 1.3 mmol) in
THF (5 mL) was added a solution of 12b · 1.5OEt2 (1.115 g, 1.3
mmol) in THF (10 mL) at about -80 °C. The mixture was stirred
at room temperature for 1 h and at 60 °C overnight. Volatiles were
removed in vacuo, and the residue was dissolved in CH2Cl2. The
solution was filtered and the filtrate was distilled to dryness. The
residual solid was dissolved in toluene and then concentrated to
give a red solid of 13b · PhCH3 (0.884 g, 73.4%), mp 117-119
°C. Anal. Calcd for C50H49N2P2NiCl · C7H8: C, 73.92; H, 6.20; N,
3.02. Found: C, 73.94; H, 6.43; N, 3.39. The sample for NMR
spectral analyses was crystallized from Et2O. 1H NMR (CDCl3): δ
0.82 (d, J ) 5.1 Hz, 6H, Pri), 0.86 (d, J ) 5.1 Hz, 6H, Pri), 1.21
(t, J ) 5.1 Hz, Et2O), 2.11 (dd, J ) 7.2, 9.9 Hz, 1H, CH2), 2.29
(dd, J ) 3.3, 9.9 Hz, 1H, CH2), 3.33-3.43 (m, 2H, Pri), 3.48 (t, J
) 5.1 Hz, Et2O), 4.17-4.25 (m, 1H, CH), 6.24 (dd, J ) 3.9, 6 Hz,
1H, Ar), 6.45 (dt, J ) 1.5, 5.1 Hz, 1H, Ar), 6.76-6.87 (m, 4H,
Ar), 6.95 (d, J ) 5.4 Hz, 2H, Ar), 7.02-7.20 (m, 9H, Ar),
7.24-7.32 (m, 5H, Ar), 7.35-7.48 (m, 5H, Ar), 7.52-7.57 (m,
3H, Ar), 7.70 (dd, J ) 6, 9 Hz, 2H, Ar). 13C NMR (CDCl3): δ
14.3, 22.8, 23.8, 24.0, 28.7, 31.7, 38.4 (d, J ) 14.6 Hz), 55.5, 55.7,
112.5 (d, J ) 7.9 Hz), 115.3, 115.5, 115.8, 117.1, 119.3 (d, J )
2.7 Hz), 122.9, 126.9, 127.2, 128.26, 128.3, 128.34, 128.4, 128.5,
128.6, 128.7, 128.9, 131.3, 132.4, 132.5, 132.7, 132.9, 133.0, 133.2,
133.5, 142.8 (d, J ) 7.3 Hz), 150.3 (d, J ) 4.5 Hz). 31P NMR
(CDCl3): δ -28.77, -5.30. HR-MS (EI): m/z 832.2414 [M]+, calcd
832.2412.
1
78.66; H, 7.33; N, 3.40. H NMR (C6D6): δ 0.73 (d, J ) 6.6 Hz,
3H, Pri), 1.24 (t, J ) 6 Hz, 9H, Et2O), 1.36 (d, J ) 5.7 Hz, 3H,
Pri), 1.38 (d, J ) 5.7 Hz, 3H, Pri), 1.57 (d, J ) 6.6 Hz, 3H, Pri),
2.31-2.38 (m, 2H, CH2), 3.47 (q, J ) 6 Hz, 9H, Et2O), 3.58-3.68
(m, 1H, Pri), 4.22-4.32 (m, 1H, Pri), 4.62-4.70 (m, 1H, CH),
6.22-6.28 (m, 1H, Ar), 6.63 (t, J ) 6.9 Hz, 1H, Ar), 6.80 (d, J )
6.9 Hz, 2H, Ar), 6.96-7.36 (m, 22H, Ar), 7.49 (t, J ) 7.5 Hz, 2H,
Ar), 7.57 (t, J ) 8.7 Hz, 2H, Ar), 8.01-8.07 (m, 2H, Ar). 13C
NMR (C6D6): δ 14.4, 15.6, 23.1, 23.9, 24.3, 24.6, 29.1, 29.3, 32.0,
65.9, 120.3, 123.1, 123.6, 126.8, 128.4, 128.5, 128.6, 128.7, 129.1,
129.6, 130.6, 131.1, 131.4, 132.1, 132.3, 132.5, 132.6, 132.8, 132.9,
133.0, 133.1, 135.0, 135.2, 142.6, 143.0, 143.1. 31P NMR (C6D6):
δ -26.07, 12.65.
[Ni(Cl){N{CH(Ph)CH2PPh2}C6H4{P(Ph2)dNC6H4Me-4}-2}] (13a).
To a solution of (DME)NiCl2 (0.118 g, 0.537 mmol) in THF (5
mL) was added a solution of 12a · OEt2 (0.401 g, 0.534 mmol) in
THF (5 mL) at about -80 °C. The mixture was warmed to room
temperature and stirred overnight. Volatiles were removed in vacuo,
and the residue was washed with hexane and then dissolved in
CH2Cl2. The solution was filtered and the filtrate was distilled to
X-ray Crystallography. Single crystals were mounted in Lin-
demann capillaries under nitrogen. Diffraction data were collected

5656 Organometallics, Vol. 27, No. 21, 2008
Sun et al.
on a Bruker Smart CCD area detector with graphite-monochromated
Mo KR radiation (λ ) 0.71073 Å). The structures were solved by
direct methods using SHELXS-9720 and refined against F2 by full-
matrix least-squares using SHELXL-97.21 Hydrogen atoms were
placed in calculated positions. Crystal data and experimental details
of the structure determinations are listed in Table 3.
General Procedures for the Kumada Reaction. A Schlenk tube
was charged with 11 (15 mg, 0.02 mmol), THF (1.2 mL), and
chlorobenzene (0.1126 g, 1 mmol) to form a homogeneous solution.
To the stirred solution was added dropwise a solution of
p-MeC6H4MgBr in THF (1.3 mmol, ca. 1 M in THF) at room
temperature. Stirring was continued at room temperature for 36 h.
The reaction was ceased by addition of water (5 mL). The mixture
was extracted with Et2O (3 × 5 mL), and the combined organic
layers were dried over anhydrous Na2SO4. The Na2SO4 was
removed by filtration and washed with Et2O. The resulting Et2O
solution was concentrated by rotary evaporation, and the residue
was purified by column chromatography on silica gel (hexane) to
afford p-MeC6H4Ph (0.157 g, 93.3%) as colorless crystals.
Acknowledgment. This work was supported by the
National Natural Science Foundation of China (20772119),
Research Fund for the Doctoral Program of Higher Education
of China (20070358031), and the Natural Science Foundation
of Anhui Province (070416238). The authors thank Profes-
sors H.-G. Wang, H.-B. Song, and D.-Q. Wang for determin-
ing the crystal structures.
Supporting Information Available: X-ray crystallographic files
reported in this paper in CIF format for the structure determinations
of 2, 5′, 6, and 13a may be obtained free of charge via the Internet
at http://pubs.acs.org.
(20) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467–473.
(21) Sheldrick, G. M. SHELXL97, Programs for structure refinement;
Universita¨t Go¨ttingen, 1997.
OM800580P