Coupling of coordinated 2-iminophosphorano-1-phosphaallyl leading to bridged iminophosphoranato complexes of zirconium and hafnium

Article abstract of DOI:10.1021/ic0259179

Reaction of MCl₄ (M = Zr, Hf) with 2 equiv of 2- iminophosphorano-1-phosphaallyl lithium [Li{P(Ph)C(=CHPh)P(Me)₂=NSiMe₃}- (THF)_1.5] (1) affords ligand coupling complexes 3 and 4, respectively, while similar trea

Full text of DOI:10.1021/ic0259179

Inorg. Chem. 2002, 41, 5934−5936
Coupling of Coordinated 2-Iminophosphorano-1-phosphaallyl Leading to
Bridged Iminophosphoranato Complexes of Zirconium and Hafnium
Zhong-Xia Wang* and Ye-Xin Li
Department of Chemistry, UniVersity of Science and Technology of China,
Hefei, Anhui 230026, P.R. China
Received August 1, 2002
Reaction of MCl4 (M ) Zr, Hf) with 2 equiv of 2-iminophosphorano-
1-phosphaallyl lithium [Li{P(Ph)C(dCHPh)P(Me)2dNSiMe3}-
(THF)1.5] (1) affords ligand coupling complexes 3 and 4, respec-
tively, while similar treatment of ZrCl4 with [Li{P(Ph)C(d
C(SiMe2Bu)Ph)P(Me)2dNSiMe3}(THF)2] (2) yields ligand transfer
complex 5.
plexes mainly feature hard donor atoms such as N,N-
chelating ligands.7b-d,9 The complexes with hard/soft com-
bining ligands may display different coordination modes,
reactivity, or catalytic activity.2b,c Herein, we report the
reaction of MCl4 (M ) Zr, Hf) with the anioic P,N-ligands
and the structural characterization of the produced ligand
coupling and ligand transfer complexes.
t
The reactions of iminophosphorano-1-phosphaallyl lithium
with MCl4 (M ) Zr, Hf) are shown in Scheme 1. Treatment
of MCl4 (M ) Zr, Hf) with 2 equiv of 1 in Et2O results in
the formation of yellow-brown solution, from which com-
P,N-Chelating ligands continue to attract considerable
attention in coordination and organometallic chemistry
because of their ability to act as hemilabile ligands.1 This
class of ligands possesses a combination of hard and soft
donor atoms and can stabilize metal ions in a variety of
oxidation states and geometries.2 A number of early and late
metal complexes of such ligands have been obtained, and
some of them showed versatile reactivity or catalytic
activity.3-5 Recently, we prepared a new class of anionic
P,N-ligands containing an iminophosphorano group,
[P(Ph)C{dC(R)Ph}P(Me)2dNSiMe3]- (R ) H, SiMe2But).6
Attempts have been made to investigate their complexation
with group 4 metal ions. Group 4 metal complexes have been
extensively explored because of their potential application
in organic synthesis and as catalysts for R-olefin polymer-
ization.7 Some group 4 metal-assisted coupling reactions have
also attracted increasing attention.8 However, these com-
(6) Wang, Z.-X.; Li, Y.-X. Organometallics, in press. NMR spectral data,
1. 1H NMR (400.1 MHz, C6D6): δ 0.23 (s, 9H, SiMe3), 1.44 (d, J )
11.68 Hz, 6H, PMe), 1.23-1.26 (m, 6H, THF), 3.44-3.47 (m, 6H,
THF), 6.74-6.80 (m, 1H, dCH), 6.92-7.02 (m, 4H, Ph), 7.13-7.17
(m, 2H, Ph), 7.32-7.36 (t, J ) 7.32 Hz, 2H, Ph), 7.93 (d, J ) 7.96
Hz, 2H, Ph). 13C{1H} NMR (100.6 MHz, C6D6): δ 4.91, 19.81 (d, J
) 59.58 Hz), 25.88, 68.83, 121.32, 126.61, 127.72 (d, J ) 7.04 Hz),
129.15, 130.25 (d, J ) 18.91 Hz), 131.00 (d, J ) 2.31 Hz), 131.51,
134.70 (d, J ) 17.20 Hz), 137.25 (d, J ) 23.23 Hz), 139.63 (d, J )
24.75 Hz). 31P{1H} NMR (161.9 MHz, C6D6): δ -46.60, 25.76. 2.
1H NMR (400.1 MHz, C6D6): δ 0.06 (s, 9H, SiMe3), 0.14-0.50 (b,
3H, SiMe), 0.82-1.14 (b, 3H, SiMe), 1.29 (s, 9H, But), 1.42-1.46
(m, 8H, THF), 3.61-3.64 (m, 8H, THF), 6.83 (t, J ) 7.21 Hz, 1H,
Ph), 7.03-7.07 (m, 1H, Ph), 7.11-7.18 (m, 6H, Ph), 7.38 (t, J )
6.87 Hz, 2H, Ph). 13C{1H} NMR (100.6 MHz, C6D6): δ 0.85, 4.86,
20.29, 26.05, 30.76, 68.97, 158.26 (dd, J ) 63.38, 58.95 Hz), 166.27
(dd, J ) 30.58, 8.35 Hz), 19.75, 126.39, 127.99 (d, J ) 4.23 Hz),
129.18 (d, J ) 8.81 Hz), 129.43, 148.26 (t, J ) 11.67 Hz), 159.03,
159.62. 31P{1H} NMR (161.9 MHz, C6D6): δ -27.72, 17.74.
(7) See, for example: (a) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F.
Angew. Chem., Int. Ed. 1999, 38, 428. (b) Vollmerhans, R.; Rabim,
M.; Tomaszewski, R.; Xin, S. X.; Taylor, N. J.; Collins, S. Organo-
metallics 2000, 19, 2161. (c) Deelman, B.-J.; Hitchcock, P. B.; Lappert,
M. F.; Leung, W.-P.; Lee, H.-K.; Mak, T. C. W. Organometallics
1999, 18, 1444. (d) Vollmerhans, R.; Shao, P.; Taylor, N. J.; Collins,
S. Organometallics 1999, 18, 2731.
* To whom correspondence should be addressed. E-mail: zxwang@
ustc.edu.cn.
(1) (a) Gavrilov, K. N.; Polosukhin, A. I. Russ. Chem. ReV. 2000, 69,
661. (b) Espinet, P.; Soulantica, K. Coord. Chem. ReV. 1999, 193-
195, 499. (c) Cheng, H.; Zhang, Z.-Z. Coord. Chem. ReV. 1996, 147,
1. (d) Newkome, G. R. Chem. ReV. 1994, 94, 1163.
(2) (a) Witt, M.; Roesky, H. W. Chem. ReV. 1994, 94, 1163. (b) Kwong,
F. Y.; Chan, A. S. C.; Chan, K. S. Tetrahedron 2000, 56, 8893. (c)
Jalil, M. A.; Fujinami, S.; Nishikawa, H. J. Chem. Soc., Dalton Trans.
2001, 1091.
(3) (a) Song, H.-B.; Zhang, Z.-Z.; Mak, T. C. W. Polyhedron 2002, 21,
1043. (b) Coles, S. J.; Durran, S. E.; Hursthouse, M. B.; Slawin, A.
M. Z.; Smith, M. B. New J. Chem. 2001, 25, 416. (c) Braunstein, P.;
Pietsch, J.; Chauvin, Y.; Mercier, S.; Saussine, L.; DeCian, A.; Fischer,
J. J. Chem. Soc., Dalton Trans. 1996, 3571. (d) van den Beuken, E.
K.; Meetsma, A.; Kooijman, H.; Spek, A. L.; Feringa, B. L. Inorg.
Chim. Acta 1997, 264, 171.
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Champkin P. A.; Clegg, W. Organometallics 2002, 21, 1383. (b) Ong,
T. G.; Wood, D.; Yap, G. P. A.; Richeson, D. S. Organometallics
2002, 21, 1. (c) Dupuis, L.; Pirio, N.; Meunier, P.; Igau, A.; Donnadieu,
B.; Majoral, J.-P. Angew. Chem., Int. Ed. Engl. 1997, 36, 987. (d)
Barluenga, J.; Sanz, R.; Fananas, F. J. J. Org. Chem. 1997, 62, 5953.
(e) Kloppenburg, L.; Petersen, J. L. Organometallics 1997, 16, 3548.
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122, 10345. (g) Barluenga, J.; Sanz, R.; Fananas, F. J. Chem.sEur.
J. 1997, 3, 1324 and references therein.
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Organometallics 1999, 18, 1693. (b) Galsworthy, J. R.; Green, M. L.
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5934 Inorganic Chemistry, Vol. 41, No. 23, 2002
10.1021/ic0259179 CCC: $22.00 © 2002 American Chemical Society
Published on Web 10/17/2002

COMMUNICATION
Scheme 1
plexes 3 and 4 can be isolated in 33.8% and 51.1% yields,
respectively, by crystallization from Et2O (for 3) or CH2Cl2
(for 4). In each case, no other crystalline species can be
obtained. Reaction between ZrCl4 and 2 equiv of 2 in Et2O
produces a deep red solution with precipitates. From the
reaction mixture, complex 5 was obtained as the only
crystalline product in 31.1% yield by crystallization from a
mixed solvent of CH2Cl2 and Et2O. It is proposed that the
reaction between MCl4 (M ) Zr, Hf) and 1 proceeds through
[PhPC(dCHPh)P(Me)2dNSiMe3]2MCl2 intermediate similar
to 5, followed by an intramolecular cross conjugate addition
between the two ligands. That no ligand coupling takes place
in the reaction of 2 with ZrCl4 is ascribed to steric hindrance
of the SiMe2But group attached on the carbon-carbon double
bond of the ligand.
Figure 1. Molecular structure of 3 shown with 30% thermal ellipsoids.
Selected bond lengths (Å) and angles (deg): Zr(1)-C(1) 2.425(8), Zr(1)-
C(3) 2.427(9), Zr(1)-N(1) 2.249(7), Zr(1)-N(2) 2.256(7), Zr(1)-Cl(1)
2.461(3), Zr(1)-Cl(2) 2.428(3), Cl(1)-Zr(1)-Cl(2) 133.01(10), C(1)-
Zr(1)-N(1) 68.3(3), C(3)-Zr(1)-N(2) 67.7(3), N(1)-Zr(1)-N(2)
158.1(3), C(1)-Zr(1)-C(3) 68.0(3).
two sets of signals, consistent with their respective chemical
environment. The 1H and 13C{1H} NMR spectra of complex
5 also reveal that two 2-imino-phosphorano-1-phosphaallyl
ligands symmetrically chelate to the zirconium center in
solution.
Complex 3 crystallizes with two molecules in the asym-
metric unit (Figure 1, only one molecule shown).13 The
bridged ligand chelates to the zirconium atom through carbon
and nitrogen atoms. The zirconium atom is six-coordinate,
having a strongly distorted octahedral geometry with trans-
apical chloride ligands. The bond angle of Cl(1)-Zr(1)-
Cl(2) is 133.01(10)°. The C(1)-Zr(1)-C(3) bond angle
[68.0(3)°] is much narrower than that of N(1)-Zr(1)-N(2)
[158.1(3)°] because of the rigidity of the bridged ligand. In
the bridged ring consisting of Zr(1), C(1), C(2), P(4), C(3),
C(4), and P(3) atoms, the phenyl group attached to P(4)
adopts exo-orientation, and the others are endo (Chart 1a).
The structure of complex 4 is shown in Figure 2.14 In the
Both 3 and 4 are pale yellow crystals, while 5 is a deep
red crystalline solid. Complex 3 is stable in the solid state
but decomposes slowly in the Et2O solution in the course of
crystallization, and the decomposed species cannot be
redissolved in organic solvents such as Et2O and THF. Both
4 and 5 are stable either in the solid state or in the solution.
Each of complexes 3-5 is very soluble in CH2Cl2 and
soluble in Et2O and gives satisfactory microanalytical data
1
(except 3), as well as H, 13C{1H}, and 31P{1H} NMR
spectra.10-12 Single-crystal X-ray diffraction data established
molecular structures of the complexes.
1
1
(12) Spectral data for 5. H NMR (400.1 MHz, CDCl3): δ -0.06 (s, 6H,
The H and 13C{1H} NMR spectra of complexes 3 and 4
SiMe2), 0.08 (s, 18H, SiMe3), 0.30 (s, 6H, SiMe2), 1.07 (s, 18H, But),
1.20 (d, J ) 10.67 Hz, 6H, PMe), 1.22 (t, J ) 6.96 Hz, 6H, Et2O),
1.92 (d, J ) 10.88 Hz, 6H, PMe), 3.49 (q, J ) 6.96 Hz, 4H, Et2O),
5.31(s, 1.2H, CH2Cl2), 6.92 (t, J ) 7.26 Hz, 2H, Ph), 7.11-7.17 (m,
6H, Ph), 7.22-7.38 (m, 8H, Ph), 7.69-7.71 (b, 4H, Ph). 13C{1H}
NMR (100.6 MHz, CDCl3): δ -0.64, -0.34, 5.58, 15.37, 19.63, 21.10
(d, J ) 55.33 Hz), 23.66 (d, J ) 45.67 Hz), 29.28, 53.50, 65.93,
122.56, 126.11, 126.49, 127.56, 127.98 (d, J ) 14.99 Hz), 129.04,
131.06 (t, J ) 8.15 Hz), 144.60 (t, J ) 7.55 Hz), 151.25 (t, J ) 22.13
Hz), 155.23-156.08 (m). 31P{1H} NMR (161.9 MHz, CDCl3): δ
32.23, 43.77.
give a set of SiMe3 and metal-bound carbon signals, showing
that the iminophosphoranato moieties equally chelate to the
metal center. The phosphorus-bound methyl groups exhibit
(10) Spectral data for 3. 1H NMR (400.1 MHz, C6D6): δ 0.42 (s, 18H,
SiMe3), 0.63 (d, J ) 12.24 Hz, 6H, PMe), 1.35 (d, J ) 11.74 Hz, 6H,
PMe), 5.27-5.35 (m, 2H, CH), 6.43-6.68 (m, 2H, Ph), 6.86-6.90
(m, 2H, Ph), 6.95-7.04 (m, 6H, Ph), 7.26-7.51 (m, 4H, Ph), 7.50 (d,
J ) 7.14 Hz, 4H, Ph), 7.89 (b, 2H, Ph). 13C{1H} NMR (100.6 MHz,
C6D6): δ 3.78, 16.97 (d, J ) 58.25 Hz), 21.40 (d, J ) 48.09 Hz),
44.96 (m), 47.13-47.63 (m), 50.05 (m), 126.19 (d, J ) 12.17 Hz),
127.09, 128.92, 129.67, 131.41, 137.15 (dd, J ) 7.85, 11.97 Hz),
138.62-139.45 (m), 142.05-142.13 (m), 143.70 (t, J ) 8.55 Hz).
31P{1H} NMR (161.9 MHz, C6D6): δ 28.18, 37.34.
(13) Although 3 decomposes slowly in solution, crystalline 3 is stable, and
no effect was observed during X-ray diffraction data collection. Crystal
data for 3: C38H52Cl2N2P4Si2Zr, M ) 879.00, monoclinic, space group
P2(1)/c, a ) 13.072(3) Å, b ) 16.424(4) Å, c ) 40.458(10) Å, â )
92.040(4)°, V ) 8681(4) Å3, T ) 298(2) K, Z ) 8, µ(Mo KR) )
(11) Spectral data for 4. 1H NMR (400.1 MHz, C6D6): δ 0.39 (s, 18H,
SiMe3), 0.58 (d, J ) 11.94 Hz, 6H, PMe), 1.36 (d, J ) 11.72 Hz, 6H,
PMe), 4.30 (s, 2H, CH2Cl2), 5.28-5.35 (m, 2H, CH), 6.41-6.83 (m,
2H, Ph), 6.96-7.05 (m, 8H, Ph), 7.18-7.29 (b, 4H, Ph), 7.47 (d, J )
7.05 Hz, 4H, Ph), 7.85-7.88 (m, 2H, Ph). 13C{1H} NMR (100.6 MHz,
C6D6): δ 3.15, 16.17 (d, J ) 58.05 Hz), 24.03 (d, J ) 55.23 Hz),
44.48-44.65 (m), 46.04-46.57 (m), 50.18 (dm, J ) 62.56 Hz), 53.11,
126.02, 127.00, 128.04, 128.16, 128.35, 128.85, 129.70, 131.35,
137.30-137.51 (m), 138.90 (b), 138.54 (dd, J ) 13.88, 26.36 Hz),
142.62, 142.94 (d, J ) 18.81 Hz), 144.47 (t, J ) 9.26 Hz). 31P{1H}
NMR (161.9 MHz, C6D6): δ 26.15, 33.65.
0.608 mm-1, 37410 reflections measured, 12190 unique (Rint
)
0.1638), R1 ) 0.0667, wR2 ) 0.1146 [I > 2σ(I)]. Crystallographic
data have been deposited with the Cambridge Crystallographic Data
Centre, CCDC reference number: 184921.
(14) Crystal data for 4‚CH2Cl2: C39H54Cl4HfN2P4Si2, M ) 1051.19,
monoclinic, space group C2/c, a ) 15.457(2) Å, b ) 18.370(3) Å, c
) 16.999(3) Å, â ) 104.379(2)°, V ) 4675.4(12) Å3, T ) 298(2) K,
Z ) 4, µ(Mo KR) ) 2.677 mm-1, 11909 reflections measured, 4004
unique (Rint ) 0.0316), R1 ) 0.0258, wR2 ) 0.0467 [I > 2σ(I)].
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre, CCDC reference number: 184922.
Inorganic Chemistry, Vol. 41, No. 23, 2002 5935

COMMUNICATION
Chart 1. Orientations of Phenyl Groups in Complexes 3 (a) and 4 (b)a
a Only bridging ring moieties shown for clarity.
Figure 3. Molecular structure of complex 5 shown with 30% thermal
ellipsoids. Selected bond lengths (Å) and angles (deg): Zr(1)-P(1)
2.7698(15), Zr(1)-P(3) 2.7596(15), Zr(1)-N(1) 2.210(4), Zr(1)-N(2)
2.215(4), Zr(1)-Cl(1) 2.4237(15), Zr(1)-Cl(2) 2.4405(16), Cl(1)-Zr(1)-
Cl(2) 170.96(6), P(1)-Zr(1)-N(1) 78.66(12), P(3)-Zr(1)-N(2) 78.22(11),
N(1)-Zr(1)-N(2) 119.67(16), P(1)-Zr(1)-P(3) 83.45(4).
The P(1) and P(3) atoms are adjacent, showing cis-arrange-
ment of the equatorial coordination atoms. The CdC bonds
are on opposite sides of the equatorial plane. However, in
the solution, 5 may exist as an equilibrium mixture of isomers
with the CdC bonds on the same and opposite sides of the
equatorial plane because only the isomer with the CdC
bonds on the same sides of the plane could form a complex
analogous to 3 according to the assumption that complexes
analogous to 5 are precursors to 3. The bond angles N(1)s
Zr(1)sN(2) and P(1)sZr(1)sP(3) are 119.67(6)° and
83.45(4)°, respectively. The average ZrsN distance of 2.213
Å is shorter than those in complex 3 (av 2.253 Å), but both
are within the range usually found for molecules containing
a ZrsN bond such as [Zr{N(SiMe3)C(But)C(H)(C5H4N-2)}2-
Cl2],7c [Zr(NMe2)3{4-ButC6H4CHP(Ph)2dNC6H2Me3-2,4,6}],16
and [Zr{(NC6H4Me-4)2P(Ph)2}2Cl2].7d
In summary, a new P-C coupling reaction at a zirconium
or hafnium center has been discovered in the reaction of
2-iminophosphorano-1-phosphaallyl lithium with MCl4
(M ) Zr, Hf). The reaction is dependent on the steric
hindrance of substituted groups attached on the carbon-
carbon double bond of the ligand. The existence of bulky
substituents on the carbon-carbon double bond prevents the
coupling reaction, producing a ligand transfer complex.
Figure 2. Molecular structure of complex 4 shown with 30% thermal
ellipsoids. Selected bond lengths (Å) and angles (deg): Hf(1)-N(1)
2.245(3), Hf(1)-C(2) 2.366(3), Hf(1)-Cl(1) 2.4203(9), P(1)-N(1)
1.607(3), P(1)-C(2) 1.756(3), P(2)-C(2) 1.871(3), Cl(1)-Hf(1)-Cl(1A)
126.97(5), N(1)-Hf(1)-N(1A) 158.64(13), C(2)-Hf(1)-C(2A) 68.70(15),
C(2)-Hf(1)-N(1) 68.15(10).
asymmetric unit of 4, a solvent CH2Cl2 molecule is also
present which does not show any interaction with the
organohafnium complex. Complex 4 has a similar skeletal
structure to that of 3. However, compared with complex 3,
the bond angle Cl(1)-Hf(1)-Cl(1A) [126.97(5)°] is nar-
rower. In the bridged ring consisting of Hf(1), C(2), P(2),
C(1A), C(2A), P(2A), and C(1) atoms, both phenyl groups
attached to P(2) and P(2A) atoms adopt exo-orientation,
being different from those of complex 3 (Chart 1b). One of
the reasons may be, if both phenyl groups on the phosphorus
atoms in complex 3 adopted exo-orientation, the repulsion
between the chlorine atoms and the exo-phenyl groups would
be stronger than that in complex 4 because of the wider Cl-
Zr-Cl angle.
The structure of crystalline complex 5 (Figure 3)15 reveals
a quasioctahedral coordination environment about the metal.
The equatorial plane is defined by Zr(1)N(1)N(2)P(1)P(3)
(∑Zr ) 359.99°) with Cl(1) and Cl(2) in trans-apical
positions. The bond angle Cl(1)sZr(1)sCl(2) is 170.96(6)°.
Acknowledgment. This research was supported by The
National Natural Science Foundation of China (Project Code
20072035) and The Ministry of Education, PRC. We thank
professors D.-Q. Wang and J.-M. Dou for X-ray structure
determinations.
Supporting Information Available: Synthetic procedure of
3-5. X-ray crystallographic files for 3, 4‚CH2Cl2, and 5 in CIF
format. This material is available free of charge via the Internet at
http://pubs.acs.org.
(15) X-ray quality single crystals of 5 were obtained by slow recrystalli-
zation of the adduct 5‚Et2O‚0.6CH2Cl2 from its Et2O solution. Crystal
data for 5: C50H80Cl2N2P4Si4Zr, M ) 1107.52, monoclinic, space
group P2(1)/c, a ) 11.6893(17) Å, b ) 21.514(3) Å, c ) 26.308(4)
Å, â ) 92.633(2)°, V ) 6609.1(17) Å3, T ) 298(2) K, Z ) 4, µ(Mo
KR) ) 0.446 mm-1, 27827 reflections measured, 9086 unique (Rint
) 0.0712), R1 ) 0.0512, wR2 ) 0.1110 [I > 2σ(I)]. Crystallographic
data have been deposited with the Cambridge Crystallographic Data
Centre, CCDC reference number: 184923.
IC0259179
(16) Said, M.; Thornton-Pett, M.; Bochmann, M. J. Chem. Soc., Dalton
Trans. 2001, 2844.
5936 Inorganic Chemistry, Vol. 41, No. 23, 2002