Bis(diphenylphosphino)methane-phosphonate ligands and their PD(II), Ni(II) and Cu(I) complexes. Catalytic oligomerization of ethylene

Article abstract of DOI:10.1021/ic8020436

The bis(diphenylphosphino)methane-phosphonate-based (dppm-phosphonate) ligands (Ph₂P)2CHP(O)(OR)₂ (R = Me, L¹; R = Ph, L²) form metal complexes by selective coordination of the diphosphine moiety to Pd(ll) and Ni(ll) centers. The formation of complexes containing the chelating, deprotonated form of ligand L¹ or L ² occurred when basic ligands were present in the precursor complex, such as Me or dmba (on Pd(ll)) or acac (on Ni(ll)). The Cu(l) complex [CuL ¹]₂(BF₄)₂ (9) was obtained that is suggested to be dinuclear, each Cu(l) being chelated by a phosphine and a P=O donor and further bound to the phosphine group of another ligand. The crystal structures of the mononuclear complexes [PdCI₂{(Ph₂P) ₂CHP(O)(OMe)₂-P,P}] (2a), [PdCI₂{(Ph ₂P)₂CHP(0)(OPh)₂-P,P}] (2b), [Pd{(Ph ₂P)₂CP(O)(OMe)₂-P,P}₂] (6a) in 6a-2CH₂CI₂, [Pd{(Ph₂P)₂CP(O)(OPh) ₂-P,P}₂] (6b), [Ni{(Ph₂P)₂CP(O)(OMe) ₂-P,P}₂] (10a) in 10a-4CHCI3, [Ni{(Ph₂P) ₂CP(O)(OPh)₂-P,P}₂] (10b) in 10b-4CHCI ₂, [NiCI₂{(Ph₂P)₂CHP(O)(OMe) ₂-P,P}] (11a) in 11a. CHCI₃ and of the dinuclear complexes [Pdμ-CI){(Ph₂P)₂CP(O)(OMe)₂-P,P}] ₂ (7a) and [Pd(μ-CI){(Ph₂P)₂CP(O)(OPh) ₂-P,P}]₂ (7b) have been determined by X-ray diffraction. The complexes [Ni{(Ph₂P)₂CC(O)NPh₂-P,P} ₂] (13) and [Ni{Ph₂PC-(Ph)P(O)(OEt)₂-P,O} ₂] (15) were prepared by reaction of [Ni(acac)₂] with the known, neutral ligands (Ph₂P)₂CHC(O)NPh₂ and Ph₂PCH(Ph)P(O)(OEt)₂, respectively. The Ni(ll) complexes were evaluated for the catalytic oligomerization of ethylene and afforded similar results when AIEtCI₂ was used as cocatalyst. Complexes 11a,b were the most active, with a turnover frequency (TOF) of 78 300 mol of C ₂H₄/(mol of Ni)h) for complex 11b in the presence of 10 equiv of AIEtCI₂ and showed a high selectivity for C₂ and C₂ olefins with up to 93% C₂ for 10a in the presence of 6 equiv AIEtCI₂, whereas when only 3 equiv cocatalyst was used with 10a, 64% trimers were observed. In the presence of methylalumoxane (MAO) as cocatalyst, precatalysts 10a,b, 11a,b, and 15 gave moderate TOFs, up to 11 660 mol of C₂H₄/(mol of Ni)h) for complex 11a with 400 equiv of MAO. Mostly ethylene dimers were formed but up to 39% trimers were observed with 10a in the presence of 400 equiv MAO.

Full text of DOI:10.1021/ic8020436

Inorg. Chem. 2009, 48, 1624-1637
Bis(diphenylphosphino)methane-Phosphonate Ligands and Their Pd(II),
Ni(II) and Cu(I) Complexes. Catalytic Oligomerization of Ethylene
Adel Hamada and Pierre Braunstein*
Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), UniVersite´ Louis
Pasteur, 4 rue Blaise Pascal, F-67070 Strasbourg Cedex, France
Received October 24, 2008
The bis(diphenylphosphino)methane-phosphonate-based (dppm-phosphonate) ligands (Ph2P)2CHP(O)(OR)2 (R )
Me, L1; R ) Ph, L2) form metal complexes by selective coordination of the diphosphine moiety to Pd(II) and Ni(II)
centers. The formation of complexes containing the chelating, deprotonated form of ligand L1 or L2 occurred when
basic ligands were present in the precursor complex, such as Me or dmba (on Pd(II)) or acac (on Ni(II)). The Cu(I)
complex [CuL1]2(BF4)2 (9) was obtained that is suggested to be dinuclear, each Cu(I) being chelated by a phosphine and
a PdO donor and further bound to the phosphine group of another ligand. The crystal structures of the mononuclear
complexes [PdCl2{(Ph2P)2CHP(O)(OMe)2-P,P}] (2a), [PdCl2{(Ph2P)2CHP(O)(OPh)2-P,P}] (2b), [Pd{(Ph2P)2CP(O)(OMe)2-
P,P}2] (6a) in 6a· 2CH2Cl2, [Pd{(Ph2P)2CP(O)(OPh)2-P,P}2] (6b), [Ni{(Ph2P)2CP(O)(OMe)2-P,P}2] (10a) in 10a ·4CHCl3,
[Ni{(Ph2P)2CP(O)(OPh)2-P,P}2] (10b) in 10b ·4CHCl3, [NiCl2{(Ph2P)2CHP(O)(OMe)2-P,P}] (11a) in 11a· CHCl3 and
of the dinuclear complexes [Pd(µ-Cl){(Ph2P)2CP(O)(OMe)2-P,P}]2 (7a) and [Pd(µ-Cl){(Ph2P)2CP(O)(OPh)2-P,P}]2
(7b) have been determined by X-ray diffraction. The complexes [Ni{(Ph2P)2CC(O)NPh2-P,P}2] (13) and [Ni{Ph2PC-
(Ph)P(O)(OEt)2-P,O}2] (15) were prepared by reaction of [Ni(acac)2] with the known, neutral ligands
(Ph2P)2CHC(O)NPh2 and Ph2PCH(Ph)P(O)(OEt)2, respectively. The Ni(II) complexes were evaluated for the catalytic
oligomerization of ethylene and afforded similar results when AlEtCl2 was used as cocatalyst. Complexes 11a,b
were the most active, with a turnover frequency (TOF) of 78 300 mol of C2H4/(mol of Ni)h) for complex 11b in the
presence of 10 equiv of AlEtCl2 and showed a high selectivity for C4 and C6 olefins with up to 93% C4 for 10a in
the presence of 6 equiv AlEtCl2, whereas when only 3 equiv cocatalyst was used with 10a, 64% trimers were
observed. In the presence of methylalumoxane (MAO) as cocatalyst, precatalysts 10a,b, 11a,b, and 15 gave moderate
TOFs, up to 11 660 mol of C2H4/(mol of Ni)h) for complex 11a with 400 equiv of MAO. Mostly ethylene dimers
were formed but up to 39% trimers were observed with 10a in the presence of 400 equiv MAO.
Introduction
the synthesis, coordination properties and reactivity of
multifunctional phosphine ligands containing hard and soft
donor functions, in particular of the P,O and P,N type,12-14
we describe here complexes with new dppm-phosphonate
ligands, which can behave as P,P and/or P,O chelates and
may find widespread applications in coordination chemis-
Despite the continuing interest in the design of new
functional ligands, phosphine ligands containing a phosphoryl
function, that is, phosphonate, phosphinate, or phosphate,
have received relatively little attention, although it is
established that their PdO group can coordinate to a metal
center via its oxygen atom.1-11 As part of our interest in
(6) Oberbeckmann-Winter, N.; Morise, X.; Braunstein, P.; Welter, R.
Inorg. Chem. 2005, 44, 1391.
* To whom correspondence should be addressed. E-mail: braunstein@
chimie.u-strasbg.fr. Fax: (+33) (0)3 90 24 13 22.
(7) Sgarbossa, P.; Pizzo, E.; Scarso, A.; Mazzega Sbovata, S.; Michelin,
R. A.; Mozzon, M.; Strukul, G.; Benetollo, F. J. Organomet. Chem.
2006, 691, 3659.
(8) (a) Heinicke, J.; Musina, E.; Peulecke, N.; Karasik, A. A.; Kindermann,
M. K.; Dobrynin, A. B.; Litvinov, I. A. Z. Anorg. Allg. Chem. 2007,
633, 1995. (b) Reisinger, C. M.; Nowack, R. J.; Volkmer, D.; Rieger,
B. Dalton. Trans. 2007, 272.
(1) Gahagan, M.; Mackie, R. K.; Cole-Hamilton, D. J.; Cupertino, D. C.;
Harman, M.; Hursthouse, M. B. J. Chem. Soc., Dalton Trans. 1990,
2195.
(2) Weis, K.; Rombach, M.; Vahrenkamp, H. Inorg. Chem. 1998, 37, 2470.
(3) Morise, X.; Braunstein, P.; Welter, R. Inorg. Chem. 2003, 42, 7752.
(4) Morise, X.; Braunstein, P.; Welter, R. C. R. Chimie 2003, 6, 91.
(5) Grushin, V. V. Chem. ReV. 2004, 104, 1629.
(9) Cadierno, V.; D´ıez, J.; Garc´ıa-Alvarez, J.; Gimeno, J.; Rubio-Garc´ıa,
J. Dalton Trans. 2008, 5737.
1624 Inorganic Chemistry, Vol. 48, No. 4, 2009
10.1021/ic8020436 CCC: $40.75  2009 American Chemical Society
Published on Web 01/21/2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
try.4,6,15 We focus here mostly on Pd(II) and Ni(II) com-
plexes and the catalytic properties of the latter in ethylene
oligomerization.
Table 1. Selected Structural Data in [PdCl2{(Ph2P)2CHP(O)-
(OMe)2-P,P}] (2a) and [PdCl2{(Ph2P)2CHP(O)(OPh)2-P,P}] (2b)
bond lengths (Å)
2a
2b
Pd-Cl(1)
Pd-Cl(2)
Pd-P(1)
2.353(7)
2.367(5)
2.233(1)
2.230(8)
1.870(3)
1.862(2)
1.806(3)
2.346(9)
2.360(1)
2.229(8)
2.236(2)
1.869(5)
1.859(5)
1.793(5)
Results and Discussion
Pd-P(2)
Synthesis and Characterization of the Ligands. The new
dppm-phosphonate ligands (Ph2P)2CHP(O)(OR)2 (R ) Me,
L1; R ) Ph, L2) were prepared by deprotonation of the
corresponding phosphonates MeP(O)(OR)2 (R ) Me, 1a; R
) Ph, 1b), followed by reaction with PPh2Cl (eq 1). Ligands
P(1)-C(25)
P(2)-C(25)
P(3)-C(25)
bond angles (deg)
2a
2b
L1,2 are white solids and were characterized by IR, H, and
1
Cl(1)-Pd-Cl(2)
P(1)-Pd-Cl(2)
P(2)-Pd-Cl(2)
P(1)-Pd-Cl(1)
P(2)-Pd-Cl(1)
P(1)-Pd-P(2)
Pd-P(2)-C(25)
Pd-P(1)-C(25)
P(1)-C(25)-P(2)
92.89(3)
170.28(3)
96.19(3)
96.38(3)
170.19(3)
74.76(3)
96.16(9)
95.9(1)
93.47(6)
171.69(6)
96.81(6)
94.52(5)
169.29(5)
75.09(5)
95.4(2)
31P{1H} NMR spectroscopic methods.
95.5(2)
93.8(2)
93.2(2)
ligands L1 and L2 acting as P,P chelates. The P(1)-C(25)
and P(2)-C(25) distances in 2a and 2b are longer than those
in [PdCl2(dppm-P,P)] (dppm ) Ph2PCH2PPh2).17
Although dppm is a well-known chelating ligand for
Pd(II), which can be easily opened upon reaction for
example, with nucleophilic metal reagents to form dimetallic
The 31P{1H} NMR spectrum (CDCl3) of L1 consists of a
doublet for the PPh2 groups at δ -11.1 ppm and a triplet
for the phosphonate group at δ 28.1 ppm. A similar pattern
is observed for L2 at δ -9.3 and δ 19.1 ppm, respectively.
Synthesis and Reactivity of Pd(II) Complexes.
Mononuclear Complexes. The reaction of L1 and L2 with
[PdCl2(COD)] or [PdCl2(NCPh)2] afforded the mononuclear,
square-planar complexes 2a and 2b. Their 31P{1H} NMR
spectrum contains a doublet at δ -43.9 (2J(P,P) ) 18 Hz)
and δ -42.0 (2J(P,P) ) 19 Hz) ppm, respectively, which is
assigned to the equivalent phosphine donors of a P,P
chelating ligand. Such a shielding is typical for a four-
membered ring structure.16 The PdO resonance of 2a,b
appears as a triplet at δ 17.1 (2J(P,P) ) 18 Hz) and δ 7.1
(2J(P,P) ) 19 Hz) ppm, respectively, and their IR spectrum
(KBr) contains a strong ν(PdO) absorption at 1262 and
1275 s cm-1, respectively.
Figure 1. Diamond 3.1 view of the structure of [PdCl2{(Ph2P)2CHP-
(O)(OMe)2-P,P}] (2a).
Slow diffusion of hexane into a chloroform solution of
2a and of petroleum ether into a dichlomethane solution of
2b led to the formation of yellow crystals suitable for X-ray
diffraction. Selected bond distances and angles are given in
Table 1 and a view of their molecular structure is shown in
Figures 1 and 2, respectively. The coordination geometry
around the Pd center in 2a and 2b is square planar, with the
(10) Chandrasekhar, V.; Azhakar, R.; Senapati, T.; Thilagar, P.; Ghosh,
S.; Verma, S.; Boomishankar, R.; Steiner, A.; Ko¨gerler, P. Dalton
Trans. 2008, 1150.
(11) Konar, S.; Clearfield, A. Inorg. Chem. 2008, 47, 5573.
(12) Braunstein, P. J. Organomet. Chem. 2004, 689, 3953.
(13) Braunstein, P. Chem. ReV. 2006, 106, 134.
(14) Speiser, F.; Braunstein, P.; Saussine, L. Acc. Chem. Res. 2005, 38,
784.
(15) Hamada, A.; Braunstein, P. Inorg. Chem. 2008, 47, 3934.
(16) Garrou, P. E. Chem. ReV. 1981, 81, 229.
Figure 2. Diamond 3.1 view of the structure of [PdCl2{(Ph2P)2CHP-
(O)(OPh)2-P,P}] (2b).
Inorganic Chemistry, Vol. 48, No. 4, 2009 1625

Hamada and Braunstein
Figure 3. Diamond 3.1 view of the ClsH inter- and intramolecular interactions in 2a.
five-membered rings,18,19 it was also conceivable to envisage
for L2 a P,O-chelating behavior in view of the structures of
the related complexes [PdCl(Me){Ph2PCHPhP(O)(OEt)2-
P,O}] (3)6 or cis-[Pd{Ph2PCHPhP(O)(OEt)2-P,O}2]2+.4
No classical intermolecular hydrogen bonding was detected
in 2a, but nonconventional C-H · · · Cl hydrogen bonds are
present (Figure 3). They involve the Cl(1) ligand and a C-H
atom of a phenyl group [C(22)-H(22) · · · Cl(1) ) 2.776(2)
Å)] and a methoxy C-H hydrogen atom from a phophonate
group [C(26b)-H(26b) · · · Cl(1) ) 2.855(2) Å. Furthermore,
an intramolecular interaction exists between the C(24)-H(24)
hydrogen of a phenyl group and Cl(2) [C(24)-H(24) · · ·Cl(2)
) 2.738(1) Å], and between the C(6)-H(6) phenyl hydrogen
and Cl(1) [C(6)-H(6) · · · Cl(1) ) 2.649(2) Å].
Similarly for 2b, an intermolecular interaction involves
the Cl(2) ligand and a phenyl hydrogen [C(35)-H(35) · · ·Cl(2)
) 2.843(2) Å] (Figure 4) and intramolecular interactions exist
between C(7)-H(7) and Cl(1) [C(7)-H(7) · · · C(1) 2.748(1)
Å] and C(37)-H(37) and Cl(2) [C(37)-H(37) · · · Cl(2) )
2.828(1) Å)].
Figure 4. Diamond 3.1 view of the ClsH inter- and intramolecular
interactions in 2b.
respectively (Figure 5). The dihedral angles between the
phenyl ring of the phosphonate group and these phosphine
phenyl groups are 8.9(3) and 7.2(3)°, respectively.
The dicationic complex [Pd(NCMe)2{(Ph2P)2CHP(O)-
(OMe)2-P,P}](BF4)2 (4) was prepared by chloride abstraction
from 2a with AgBF4 or, alternatively, by coordination of L1
to [Pd(NCMe)4](BF4)2 (Scheme 1). Its spectroscopic proper-
ties (see Experimental Section) confirm that the ligand
remains P,P-chelated to palladium.
In addition, intra- and intermolecular π-π interactions of
3.820(4) and 3.760(1) Å exist between a phenyl ring of the
phosphonate ligand and one of the phosphine phenyl groups,
(17) Steffen, W. L.; Palenik, G. J. Inorg. Chem. 1976, 15, 2432.
(18) Braunstein, P.; Guarino, N.; de Méric de Bellefon, C.; Richert, J.-L.
Angew. Chem., Int. Ed. Engl. 1987, 26, 88.
(19) Braunstein, P.; Oswald, B.; DeCian, A.; Fischer, J. J. Chem. Soc.,
Dalton Trans. 1991, 2685.
When the reaction between L1 and [Pd(NCMe)4](BF4)2
was performed in a 2:1 ratio, the symmetrical bischelate
complex [Pd{(Ph2P)2CHP(O)(OMe)2-P,P}2](BF4)2 (5) was
1626 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
Figure 5. PLATON view of 2b showing the inter- and intramolecular π-π interactions. Thermal parameters enclose 50% of the electron density.
Scheme 1
15.1 ppm, respectively, indicating the absence of coupling
between these nuclei. A single-crystal X-ray diffraction
analysis showed that 6a and 6b form discrete, almost
centrosymmetrical molecules in which the Pd atom is
chelated by two diphosphine moieties whereas the phospho-
nate groups remain uncoordinated (Table 2, Figures 6 and
7). The planar geometry around the sp2-hybridized PCP
carbon atom confirms the deprotonation reaction mentioned
above. Owing to the anionic nature of the coordinated diphos-
phosphonate ligand, the P-C(25) and P-C(52) bond dis-
tances (ca. 1.74 Å) are shorter than when the ligand is neutral,
as in [PdCl2(dppm-P,P)] (ca. 1.83 Å),17,20 but similar to those
in the related Pd(II) dppm-terpyridine complex A).21 Not
unexpectedly, reaction of 5 with NEt3 in CH2Cl2 afforded
6a in quantitative spectroscopic yields after a few hours.
obtained (eq 2). Its 31P{1H} NMR spectrum shows a doublet
at δ -13.6 (2J(P,P) ) 5.8 Hz) for the PPh2 groups and a
triplet at δ 15.6 (2J(P,P) ) 5.8 Hz) for the PdO resonance.
The ν(PdO) vibration occurs at 1224 s cm-1 in the IR
spectrum (KBr). Although we do not have a firm proof for
it, we believe that the orientation of the PdO groups bonded
to the tetrahedral PCP carbons is such that the molecule
possesses a center of symmetry, as do 6a,b (see below).
In contrast, the reaction of L1 or L2 with the dinuclear,
cyclometalated complex [Pd(µ-Cl)(dmba)]2 (dmbaH )
C6H5CH2NMe2) yielded the neutral, bischelate complex
[Pd{(Ph2P)2CP(O)(OMe)2-P,P}2] (6a) or [Pd{(Ph2P)2CP-
(O)(OPh)2-P,P}2] (6b), respectively, in low yield in the latter
case (eq 3).
Their formation resulted from phosphine coordination and
deprotonation by the chelated dmba ligand, which is elimi-
nated as dmbaH. The 31P{1H} NMR spectrum of 6a and 6b
contains a singlet for the phosphine donors at -31.4 and
-31.0 ppm and a singlet for the PdO moiety at 25.6 and
Dinuclear Complexes. With the original objective to study
the reactivity of the Pd-C bond of methyl complexes
containing the ligands L1 or L2, the latter were reacted with
[PdCl(Me)(COD)]. However, this reaction afforded the
dinuclear, chloride-bridged complexes [Pd(µ-Cl){(Ph2P)2-
CP(O)(OR)2-P,P}]2 (7a R ) Me; 7b R ) Ph) as yellow
(20) Barkley, J.; Ellis, M.; Higgins, S. J.; McCart, M. K. Organometallics
1998, 17, 1725.
(21) Pickaert, G.; Cesario, M.; Douce, L.; Ziessel, R. Chem. Commun. 2000,
1125.
Inorganic Chemistry, Vol. 48, No. 4, 2009 1627

Hamada and Braunstein
Table 2. Selected Structural Data in Complexes 6a·2CH2Cl2 and 6b
(sum of the angles ) 359.71° in 7a and 359.86° in 7b),
consistent with its sp2 hybridization. Because of the loss of
the PCH proton of L1 or L2, the P,P-chelating ligand is
anionic and the charge is delocalized over P(1), C(25), and
P(2), as shown by shorter P(1)-C(25) and P(2)-C(25) bond
distances of 1.742(4) and 1.743(4) Å in 7a or 1.746(2) and
1.742(2) Å in 7b, respectively, when compared to the P-C
sp3 single bond in 2a or 2b (Table 1) or in [PdCl2(dppm-
P,P)] (1.834(3), 1.830(3) Å).17
Although no classical intramolecular hydrogen bonding
was detected in 7a, an interaction between an ortho phenyl
C-H atom and a bridging Cl atom was observed [C(41)-
H(41) · · · Cl(2) ) 2.872(2) Å) (Figure 10).
In the crystal structure of 7b, an interaction between a
C-HmoietyofaphenylringandthePdcenters[C(36)H(36) · · ·Pd
) 2.872(2) Å] creates infinite cross-linked chains (Figure 11).
The chloride bridges of 7a are readily cleaved by nucleophiles
such as P(OPh)3 which affords the mononuclear complex
[PdCl{(Ph2P)2CP(O)(OMe)2-P,P}{P(OPh)3}] (8) (eq 5). Its
spectroscopic data are given in the Experimental Section.
bond lengths (Å)
6a·2CH2Cl2
6b
Pd(1)-P(1)
Pd(1)-P(2)
Pd(1)-P(4)
Pd(1)-P(5)
P(1)-C(25)
P(2)-C(25)
P(3)-C(25)
2.3441(8)
2.3229(8)
2.337(6)
2.332(2)
1.746(3)
1.759(3)
1.723(3)
2.3239(6)
2.3316(6)
2.3255(6)
2.3396(6)
1.755(2)
1.749(2)
1.722(2)
bond angles (deg)
6a·2CH2Cl2
6b
P(1)-Pd-P(2)
P(1)-C(25)-P(2)
P(4)-Pd(1)-P(5)
70.34(3)
100.2(2)
70.56(3)
70.68(2)
100.5(2)
70.71(2)
1
solids (eq 4). Their H NMR spectra indicated the absence
of the Pd-Me group and of the Ph2PCHPPh2 proton, which
have been eliminated in the form of methane. The 31P{1H}
NMR spectrum of 7a contains singlets for the equivalent
phosphine donors at δ -45.9 ppm and at δ 24.1 ppm for
the uncoordinated PdO group. These resonances are found
in 7b at δ -45.0 and 13.2 ppm, respectively. Like in 4 or
2
6a,b, no J(P,P) coupling was observed. The centrosym-
metrical structure of these new complexes was confirmed
by an X-ray diffraction study (Table 3, Figures 8 and 9).
Synthesis of a Dinuclear Cu(I) Complex. The reaction of
[Cu(NCMe)4]BF4 with one equivalent of L1 afforded a new
complex which was characterized in 31P{1H} NMR spectroscopy
by the presence of two broad signals at δ 1.4 and 28.0 ppm,
assigned to the PPh2 and P(O)(OMe) groups, respectively (eq 6).
By analogy with results obtained earlier with the diphosphine ligand
(Ph2P)2CHC(O)NPh2,22 we suggest for this complex a similar,
The palladium atom in 7a or 7b is in a square-planar
environment containing the two bridging chlorides and two
phosphine P atoms. The geometry around C(25) is planar
Figure 6. Diamond 3.1 view of the structure of [Pd{(Ph2P)2CP(O)(OMe)2-P,P}] (6a) in 6a·2CH2Cl2.
1628 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
molar ratio at room temperature in dichloromethane, the
mononuclear, diamagnetic bischelated complex [Ni{(Ph2P)2-
CP(O)(OMe)2-P,P}2] (10a) or [Ni{(Ph2P)2CP(O)(OPh)2-
P,P}2] (10b) was obtained in 70 and 90% yield, respectively
(eq 7).
The 31P{1H} NMR spectra of 10a,b contain a singlet for
the phosphine donors at -22.4 and -22.1 ppm and a singlet
for the PdO moiety at 23.1 and 12.3 ppm, respectively,
indicating again the absence of coupling between these
nuclei. In the IR spectrum (KBr), ν(PO) vibration occurs at
1232 (10a) and 1244 cm-1 (10b), ca. 15 and 21 cm-1 higher
than in the free ligand. A single-crystal X-ray diffraction
analysis of 10a · 4CHCl3 and 10b · 4CHCl3 showed that the
crystals consist of discrete neutral centrosymmetric mol-
ecules, the Ni atom being located on an inversion center,
and confirmed the chelating behavior of the phosphine donors
and the presence of two uncoordinated phosphonate groups.
A view of a molecule of 10a and 10b is shown in Figures
12 and 13, respectively. The coordination geometry around
the Ni(II) center is square planar. There are no significant
intermolecular interaction between complex 10a and the
chloroform solvate molecules, but an intramolecular
CH(19) · · · Ni interaction of 2.869(1) Å is found above and
below the metal coordination plane (Figure 12).
Figure 7. Diamond 3.1 view of the structure of [Pd{(Ph2P)2CP(O)(OPh)2-
P,P}2] (6b).
Table 3. Selected Bond Lengths and Angles in Complexes 7a and 7b
bond lengths (Å)
7a
7b
Pd(1)-P(1)
Pd(1)-P(2)
Pd(1)-Cl(1)
P(1)-C(25)
P(2)-C(25)
P(3)-C(25)
2.234(7)
2.245(6)
2.427(5)
1.742(4)
1.743(4)
1.722(4)
2.225(6)
2.236(6)
2.430(6)
1.746(2)
1.742(2)
1.718(2)
bond angles (deg)
7a
7b
P(1)-Pd-P(2)
70.85(4)
99.72(4)
170.34(4)
96.3(2)
71.11(3)
99.61(3)
170.66(3)
96.1(1)
P(1)-Pd-Cl(1)
P(2)-Pd-Cl(1)′
P(1)-C(25)-P(2)
Cl(1)-Pd-Cl(1)′
87.94(4)
88.87(3)
dinuclear structure 9, in which a dynamic behavior of the phosphine
donors accounts for the broad resonances observed.
The planar geometry around the C(25) atom adjacent to the
phosphine donors (sum of the angles ) 359.80°) is consistent
with its sp2 hybridization (Table 4). The ligand anionic charge
is delocalized over the atoms P(1), C(25), and P(2), as indicated
by the P(1)-C(25) and P(2)-C(25) bond lengths of 1.748(3)
and 1.746(3) Å in 10a and 1.755(4) and 1.750(4) Å in 10b,
respectively, which are shorter than the P-Csp3 single bond in
Synthesis and Reactivity of Ni(II) Complexes. When the
ligand L1 or L2 was reacted with [Ni(acac)2] · H2O in a 2:1
Figure 8. View of the structure of [Pd(µ-Cl)2{(Ph2P)2CP(O)(OMe)2-P,P}]2 (7a).
Inorganic Chemistry, Vol. 48, No. 4, 2009 1629

Hamada and Braunstein
Figure 9. Diamond 3.1 view of the structure of [Pd(µ-Cl){(Ph2P)2CP(O)(OPh)2-P,P}]2 (7b).
Figure 10. Intramolecular hydrogen bonding between ortho aromatic hydrogen atoms and the bridging chloride ligands in complex 7a.
2a (1.870(3), 1.862(2) Å) or 2b (1.869(5), 1.859(5) Å) or in
the Ni(II) complex [Ni(dppm)2](BF4)2 (1.81(4) and 1.82(4) Å).23
In complex 10b·4CHCl3 (Figure 13), the bonding param-
eters are very similar to those in 10a and will not be
discussed in detail.
Experimental Section). Slow diffusion of hexane into a
chloroform solution of 11a led to the formation of yellow
crystals of 11a·CHCl3 suitable for X-ray diffraction analysis.
Selected bond distances and angles are given in Table 5.
The square planar coordination geometry around the Ni(II)
center is consistent with the diamagnetism of the complex. The
geometry around the sp3-hybridized C(25) atom is tetrahedral
and as expected, the P(1)-C(25) and P(2)-C(25) bonds are
longer than in the anionic chelates of 10a.
For comparison, we extended our studies with the dppm-
phosphonate ligands L1and L2 to the dppm-C(O)NPh2
ligand 12.22 Its reaction with [Ni(acac)2] in a 2:1 molar
ratio at room temperature in dichloromethane afforded the
bischelate mononuclear complex 13 (eq 9). This complex
is diamagnetic and its 31P{1H} NMR spectrum shows a
singlet at -28.6 ppm. In the IR spectrum (KBr), the ν(CO)
vibration occurs at 1652 cm-1. Here too, spontaneous
Reaction of the ligands L1 and L2 with [NiCl2(DME)] in
a 1:1 molar ratio at room temperature in dichloromethane,
afforded quantitatively the mononuclear, diamagnetic com-
plexes [NiCl2{(Ph2P)2CHP(O)(OMe)2-P,P}] (11a) and [NiCl2-
{(Ph2P)2CHP(O)(OPh)2-P,P}] (11b), respectively (eq 8).
Their 31P{1H} NMR spectrum consists of a doublet for
the phosphine donors and a triplet for the PdO moiety (see
(22) Andrieu, J.; Braunstein, P.; Tiripicchio, A.; Ugozzoli, F. Inorg. Chem.
1996, 35, 5975.
1630 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
Figure 11. Intermolecular hydrogen bonding between a hydrogen atom of the phenyl group of the phosphonate function and the palladium center in 7b.
Similarly, reaction of the related ꢀ-phosphonato-phosphine
P,O ligand 144 with [Ni(acac)2] · H2O in a 2:1 molar ratio at
room temperature in dichloromethane was accompanied by
ligand deprotonation (eq 10). This afforded the mononuclear,
paramagnetic complex 15 in 65% yield. Its IR ν(PO)
vibration occurs at 1251 cm-1 (KBr).
Figure 12. Diamond 3.1 view of the structure of [Ni{(Ph2P)2CP(O)(OMe)2-
P,P}2] (10a) in 10a·4CHCl3 with the labeling scheme.
A Pd(II) complex containing the deprotonated form of ligand
14 featured in 15 has been previously structurally characterized.4
Table 4. Comparison of the Structural Data for
Catalytic Oligomerization of Ethylene. Chelating ligands
[Ni{(Ph2P)2CP(O)(OMe)2-P,P}2] (10a) in 10a·4CHCl3 and in
23
play a major role in the academic and industrial development
of late transition metal catalysts for the oligomerization and
polymerization of olefins.14,24-31 The discovery of the
“Nickel effect” by Ziegler in 1953 indicated that this metal
favors the oligomerization of ethylene32 and many nickel
complexes have been studied as catalysts for the oligomer-
ization and polymerization of ethylene,27,33-37 in the pres-
ence or not of a cocatalyst. The product chain length
distribution strongly depends on the ligands properties.
Anionic bidentate P,Os and neutral N,N chelating ligands
occupy central positions and the SHOP process remains a
[Ni(dppm)2](BF4)2
bond lengths (Å)
10a
10b
[Ni(dppm)2](BF4)2
Ni-P(1)
2.2177(8)
2.2178(8)
1.748(3)
1.746(3)
1.728(3)
2.2214(1)
2.2229(1)
1.755(4)
1.750(4)
1.715(4)
2.219(8)
2.228(9)
1.81(4)
1.82(4)
Ni-P(2)
P(1)-C(25)
P(2)-C(25)
P(3)-C(25)
bond angles (deg)
10a
10b
[Ni(dppm)2](BF4)2
P(1)-Ni-P(2)
P(1)-C(25)-P(2)
73.21(3)
98.4(2)
73.52(4)
98.7(2)
73.2(3)
94.0(2)
deprotonation of the diphosphine ligand has occurred
because of the presence of the basic acac ligand in the
Ni(II) precursor.
(23) Miedaner, A.; Haltiwanger, R. C.; DuBois, D. L. Inorg. Chem. 1991,
30, 417.
Inorganic Chemistry, Vol. 48, No. 4, 2009 1631

Hamada and Braunstein
Figure 13. Diamond 3.1 view of complex of [Ni{(Ph2P)2CP(O)(OPh)2-P,P}2] (10b) in 10b·4CHCl3.
the activity and selectivity of their Ni complexes (B versus
C and D),39-41
We have evaluated the P,P-nickel complexes 10a,b and
11a,b and the P,O-complex 15 as precatalysts in the presence
of as little as possible AlEtCl2 or MAO as cocatalyst. Such
a comparison should provide information about the influence
of (i) a chelating vs a monodentate ligand, (ii) the nature of
the phosphonate substituents (methyl versus phenyl groups),
(iii) the metal coordination geometry, and (iv) the nature of
the cocatalyst (AlEtCl2, or MAO). The results were also
compared with those of [NiCl2(PCy3)2], a typical R-olefin
dimerization catalyst.42,43 These precatalysts showed moder-
ate to high activities for the dimerization and trimerization
of ethylene (Tables 6 and 7).
Figure 14. Diamond 3.1 view of the structure [NiCl2{(Ph2P)2CHP(O)(OMe)2-
P,P}] (11a) in 11a·CHCl3.
Table 5. Selected Structural Data for [NiCl2{(Ph2P)2CHP(O)-
(OMe)2-P,P}] (11a) in 11a·CHCl3
bond lengths (Å)
11a
Ni-Cl(1)
Ni-Cl(2)
Ni-P(1)
2.213(6)
2.195(6)
2.133(6)
2.150(6)
1.861(2)
1.865(2)
1.799(2)
Ni-P(2)
P(1)-C(25)
P(2)-C(25)
P(3)-C(25)
All these precatalysts afforded similar results with
AlEtCl2 as cocatalyst. Complexes 11a,b were the most
active with a turnover frequency (TOF) of 78 300 mol of
bond angles (deg)
(24) Mecking, S. Angew. Chem., Int. Ed. 2001, 40, 534.
(25) Late Transition Metal Polymerization Catalysis; Rieger, B., Saunders
Baugh, L., Kacker, S., Striegler, S., Eds.; Wiley-VCH: Weinheim,
2003.
(26) Heinicke, J.; Ko¨hler, M.; Peulecke, N.; He, M.; Kindermann, M. K.;
Keim, W.; Fink, G. Chem.sEur. J. 2003, 9, 6093.
(27) Gibson, V. C.; Spitzmesser, S. K. Chem. ReV. 2003, 103, 283.
(28) McGuinness, D. S.; Gibson, V. C.; Wass, D. F.; Steed, J. W. J. Am.
Chem. Soc. 2003, 125, 12716.
Cl(1)-Ni-Cl(2)
P(1)-Ni-Cl(2)
P(2)-Ni-Cl(2)
P(1)-Ni-Cl(1)
P(2)-Ni-Cl(1)
P(1)-Ni-P(2)
Ni-P(2)-C(25)
Ni-P(1)-C(25)
P(1)-C(25)
97.69(2)
169.04(3)
93.07(2)
92.42(2)
169.17(3)
76.95(2)
95.34(6)
96.04(7)
91.35(9)
(29) Ionkin, A. S.; Marshall, W. J. J. Organomet. Chem. 2004, 689, 1057.
(30) Foley, S. R.; Shen, H.; Qadeer, U. A.; Jordan, R. F. Organometallics
2004, 23, 600.
(31) Small, B. L.; Schmidt, R. Chem.sEur. J. 2004, 10, 1014.
(32) Ziegler, K.; Gellert, H. G.; Holzkamp, E.; Wilke, G. Brennst. Chem.
1954, 35, 321.
reference in the oligomerization of ethylene with its remark-
able selectivity for LAO.38 Seemingly minor changes of the
substituents on SHOP-related P,O ligands allowing different
types of intramolecular hydrogen bonding interactions within
the ligand moiety have been shown to significantly affect
(33) Klabunde, U.; Ittel, S. D. J. Mol. Catal. A: Chem. 1987, 41, 123.
(34) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem., Int.
Ed. 1999, 38, 428.
(35) Keim, W. Angew. Chem., Int. Ed. 1990, 29, 235.
1632 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
Table 6. Catalytic Results for Complexes 10a,b, 11a,b, 15 and [NiCl2(PCy3)2] in the Oligomerization of Ethylene with AlEtCl2 as Cocatalysta
selectivity (mass %)
R-olefin (mol%)
productivity
AlEtCl2(equiv)
C4
C6
C8
C10
(g C2H4/ (g Ni)h)
TOF (mol C2H4/ (mol Ni)h)
C4
C6
C8
KR
10a
10a
10a
10a
10b
10b
11a
11a
11b
11b
15
3
6
10
14
3
10
6
10
6
10
3
6
10
14
6
34
93
83
81
90
88
60
61
59
56
90
87
85
71
59
65
64
7
<3
<1
<1
<1
450
13450
11850
12070
340
12730
31710
32310
36030
37330
200
14170
26710
14590
27600
24400
1000
29185
24860
25310
720
25000
66510
67750
75550
78300
420
24520
45830
30600
57800
51500
36
10
17
20
14
30
4
4
4
4
27
20
16
12
11
9
1.25
0.05
0.22
0.15
0.07
0.09
0.39
0.39
0.41
0.47
0.07
0.16
0.12
0.11
0.38
0.32
2
4
4
28
19
10
12
36
36
36
39
10
13
15
27
34
31
<1
4
4
4
5
<1
<1
<1
<1
1
<1
<1
<1
4
3
3
3
15
15
15
ref
5
3
2
<1
<3
34
3
10
a Conditions: T ) 23 °C, 10 bar of C2H4, 35 min, 4 × 10-5 mol Ni complex, total solvent volume 15 mL (VNi + VEADC), solvent: chlorobenzene for 10a
and toluene for 10b, 11a,b, and 15, R ) (mol of hexenes/mol of butenes). Reference: NiCl2(PCy3)2.
Table 7. Catalytic Results for Complexes 10a,b, 11a,b, 15 and [NiCl2(PCy3)2] in the Oligomerization of Ethylene with MAO as Cocatalysta
selectivity (mass %)
R-olefin (mol%)
productivity
MAO (equiv)
C4
C6
C8
C10
(g C2H4/(g Ni)h)
TOF (mol C2H4/(mol Ni)h)
C4
C6
C8
KR
10a
10a
10a
10b
10b
11a
11a
11a
11b
11b
11b
15
100
200
400
200
400
100
200
400
100
200
400
100
200
400
200
400
71
79
61
78
65
91
88
86
91
91
87
83
83
83
74
70
29
21
39
22
35
9
11
13
9
120
650
800
260
1360
1680
3130
3230
2980
8880
11660
2360
830
9320
6940
5550
7790
1200
6400
72
66
71
70
59
34
13
12
48
24
15
57
53
45
76
72
0.27
0.17
0.86
0.18
0.35
0.06
0.08
0.10
0.06
0.07
0.09
0.13
0.12
0.11
0.16
0.24
47
31
25
19
20
5
2
41
7
1490
1540
1420
4230
5560
1120
400
4440
3300
3210
3710
600
<1
39
15
2
1
<1
<1
2
<1
<1
1
<1
2
2
8
4
1
9
12
16
15
15
18
26
3
12
12
9
4
2
2
15
15
ref
ref
3000
a Conditions: T ) 23 °C, 10 bar of C2H4, 35 min, 4 × 10-5 mol Ni complex, total solvent volume 20 mL (VNi + VMAO), solvent: chlorobenzene for 10a,
toluene for 10b, 11a,b, and 15, KR ) (mol of hexenes/mol of butenes). Reference: NiCl2(PCy3)2.
C2H4/(mol of Ni)h) for complex 11b (Table 6) in the
presence of 10 equiv of AlEtCl2. All precatalyst showed
a high selectivity for C4 and C6 olefins and only traces of
C8 olefins were observed. Up to 93% C4 was obtained
with 10a in the presence of 6 equiv AlEtCl2, whereas when
only 3 equiv cocatalyst was used with 10a, 64% trimers
were formed. The mononuclear, bischelate complexes
10a,b and 15 led to higher selectivities for R-C4 than the
mononuclear complexes 11a and 11b. The use of different
amounts of AlEtCl2 as cocatalyst generally affected the
selectivity less than the productivity.
equiv of MAO. Mostly ethylene dimers were formed but
up to 39% trimers were observed with 10a in the presence
of 400 equiv MAO. This is reminiscent of the behavior
of this precatalysts in the presence of 3 equiv AlEtCl2
(see above). The R-olefins contained mostly 1-butene, but
up to 47% 1-hexene was obtained with 10a in the presence
of 200 equiv MAO.
In conclusion, we have found that bis(diphenylphosphi-
no)methane-phosphonate-based ligands (Ph2P)2CHP(O)(OR)2
(R ) Me, L1; R ) Ph, L2) form metal complexes by selective
coordination of the diphosphine moiety to Pd(II) and Ni(II)
centers, resulting in four-membered ring chelates. Spontane-
ous deprotonation of these ligands at the PCHP site occurred
when basic ligands were present in the precursor metal
complex, such as dmba or methyl in the case of Pd(II) or
acac in the case of Ni(II). A range of mono- and dinuclear
complexes was structurally characterized and some Ni(II)
complexes revealed interesting catalytic properties for the
selective oligomerization of ethylene.
In the presence MAO as cocatalyst, precatalysts 10a,b,
11a,b, and 15 gave moderate TOFs up to 11 660 mol of
C2H4/(mol of Ni)h) (Table 7) for complex 11a with 400
(36) Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. ReV. 2000, 100,
1169.
(37) Mecking, S. Coord. Chem. ReV. 2000, 203, 325.
(38) Ostoja Starzewski, K. A. In Late Transition Metal Polymerization
Catalysis; Rieger, B., Saunders Baugh, L., Kacker, S., Striegler, S.,
Eds.; Wiley-VCH: Weinheim, 2003; p 1.
(39) Braunstein, P.; Chauvin, Y.; Mercier, S.; Saussine, L.; De Cian, A.;
Fischer, J. J. Chem. Soc., Chem. Commun. 1994, 2203.
(40) Pietsch, J.; Braunstein, P.; Chauvin, Y. New J. Chem. 1998, 467.
(41) Kermagoret, A.; Braunstein, P. Dalton Trans. 2008, 822.
(42) Commereuc, D.; Chauvin, Y.; Léger, G.; Gaillard, J. ReV. Inst. Fr.
Pe´t. 1982, 37, 639.
(43) Knudsen, R. D. Prepr. -Am. Chem. Soc., DiV. Pet. Chem. 1989, 572.
Inorganic Chemistry, Vol. 48, No. 4, 2009 1633

Hamada and Braunstein
[PdCl2{(Ph2P)2CHP(O)(OMe)2-P,P}] (2a). Solid [PdCl2(COD)]
(0.579 g, 2.03 mmol) was added to a solution of (Ph2P)2-
CHP(O)(OMe)2 (1.000 g, 2.03 mmol) in CH2Cl2 (45 mL). The
mixture was stirred for 30 min, and the volatiles were removed
under reduced pressure. The residue was washed with Et2O (2 ×
10 mL) and pentane (2 × 20 mL), which afforded a yellow solid
(1.087 g, 80%). Anal. Calcd for C27H27Cl2O3P3Pd: C, 48.42; H,
Experimental Section
General Consideration. All the reactions and manipulations
were carried out under an inert atmosphere of purified nitrogen
using standard Schlenk tube techniques. The following solvents
were dried and distilled under nitrogen before use: hexane, pentane,
and toluene over sodium, tetrahydrofuran and diethyl ether over
sodium-benzophenone, and dichloromethane over calcium hydride.
Nitrogen (Air liquide, R-grade) was passed through BASF R3-11
catalyst and molecular sieve columns to remove residual oxygen
and water. Elemental C, H, and N analyses were performed by the
Service de Microanalyses (Universite´ Louis Pasteur, Strasbourg).
Infrared spectra were recorded on an IFS 66 Bruker FT-IR
spectrometer. The 1H and 31P{1H} NMR spectra were recorded at
300.1 and 121.5 MHz, respectively, on a Bruker AC300 instru-
1
4.06. Found: C, 48.50; H, 4.12. H NMR (CDCl3): δ 3.07 (6H, d,
2
2
3J(P,H) ) 11.5, OCH3), 5.30 (1H, dt, J(PO,H) ) 23 Hz, J(P,H)
) 11 Hz, CH), 7.50-8.39 (40H, m, aromatics). 31P{1H} NMR
(CDCl3): δ -43.9 (d, J(P,P) ) 18 Hz, PPh2), 17.1 (t, J(P,P) )
18 Hz). IR (KBr): νPdO ) 1262 (s) cm-1
2
2
.
[PdCl2{(Ph2P)2CHP(O)(OPh)2-P,P}] (2b). Solid [PdCl2-
(NCPh)2] (0.556 g, 1.45 mmol) was added to a solution of
(Ph2P)2CHP(O)(OPh)2 (0.875 g, 1.45 mmol) in CH2Cl2 (20 mL) at
ambient temperature. The mixture was stirred for 30 min, and the
volatiles were removed under reduced pressure. The residue was
washed with Et2O (2 × 10 mL) and pentane (2 × 20 mL), which
afforded a yellow solid (1.139 g, 99%). Anal. Calcd for
C37H31Cl2O3P3Pd: C, 55.98; H, 3.94. Found: C, 56.89; H, 4.68
(despite recrystallizations, no better analyses could be obtained).
1H NMR (CDCl3): δ 5.35 (H, dt, 2J(PO,H) ) 23 Hz, 2J(P,H) ) 13
Hz, CH), 6.32-6.35 (10H, m, OPh), 7.04-8.42 (20H, m, PPh2).
1
ment.The H NMR chemical shifts of the aromatic protons have
been omitted for clarity, since they are unexceptional. AgBF4
(Avocado) was dried overnight in vacuo before use. The chlo-
rodiphenylphosphine and the phosphonates MeP(O)(OR)2 (R ) Me,
Ph) (Aldrich) were distilled and degassed before use. The com-
pounds Ph2PCH(Ph)P(O)(OEt)2,4 (Ph2P)2CHC(O)NPh2,22 [PdCl2-
(COD)],44 [PdCl(Me)(COD)],45 [Cu(NCMe)4]BF4,46 [Pd(NCMe)4]-
(BF4)2,47,48 [Pd(µ-Cl)(dmba)]2,49 and [NiCl2(DME)] (DME ) 1,2-
dimethoxyethane)50 were prepared according to literature procedures.
(Ph2P)2CHP(O)(OMe)2 (L1). In a 250 mL Schlenk tube contain-
ing a solution of n-BuLi in hexane (30.22 mL, 48.35 mmol, 1.6 M
Aldrich) cooled at -20 °C was added a solution of diisopropylamine
(5.290 g, 48.3 mmol) in THF (30 mL). After 10 min, a solution of
MeP(O)(OMe)2 (2.000 g, 16.1 mmol) in THF (40 mL) was added,
and the mixture was stirred for 10 min during which the temperature
was kept below -65 °C. It was then cooled again to -78 °C, and
a solution of Ph2PCl (7.100 g, 5.79 mL, 32.2 mmol) in THF (20
mL) was added dropwise. The temperature was then allowed to
warm to 0 °C while stirring was maintained. The reaction mixture
was quenched at -20 °C by addition of a degassed 5N HCl solution
untill pH 4 was reached. The organic layer was then collected and
the aqueous phase was extracted with diethylether (2 × 20 mL).
The combined organic phases were then dried over degassed
MgSO4. After filtration and removal of the volatiles under vacuum,
the ligand was obtained as a white solid (6.100 g, 77%). Anal.
Calcd for C27H27O3P3: C, 65.86; H, 5.53. Found: C, 66.09; H, 5.70.
1H NMR (CDCl3): δ 3.19 (6H, d, 3J(P,H) ) 11.1 Hz, OCH3), 3.71
(1H, d, 2J(PO,H) ) 21.6 Hz, CH), 7.23-8.04 (20H, m, aromatics).
2
31P{1H} NMR (CDCl3): δ -42.0 (d, J(P,P) ) 19 Hz, PPh2), 7.1
2
(t, J(P,P) ) 19 Hz, PO). IR (KBr): νPdO ) 1275 (s) cm-1
.
[Pd{(Ph2P)2CHP(O)(OMe)2-P,P}(NCMe)2][BF4]2 (4). The com-
plex [PdCl2{(Ph2P)2CHP(O)(OMe)2-P,P}] (0.450 g, 0.67 mmol) was
treated with AgBF4 (0.261 g, 1.34 mmol) in a 1:1 mixture of
CH2Cl2/MeCN at ambient temperature. The reaction mixture was
stirred for 1 h, then the solution was filtered and the volatiles were
removed under reduced pressure to leave a gray solid, which was
washed with diethylether (2 × 15 mL) and pentane (2 × 15 mL)
and dried under vacuum (0.458 g, 80%). 1H NMR (CDCl3): δ 2.35
3
(s, 6H, CH3CN), 3.32 (d, 6H, J(P,H) 11.2 Hz, MeO), 3.87 (d,
2J(P,H) ) 12 Hz, CH), 6.55-7.89 (20H, m, aromatics). 31P{1H}
NMR (CDCl3): δ -49.0 (s, PPh2), 14.3 (s, PO). IR (KBr): νPdO
)
1261 (s) cm-1
.
The following is an alternative procedure: solid [Pd(NCMe)4]-
(BF4)2 (0.400 g, 0.90 mmol) was added to a solution of
(Ph2P)2CHP(O)(OMe)2 (0.450 g, 0.91 mmol) in CH2Cl2 (40 mL).
The mixture was stirred for 1 h, and the volatiles were removed
under reduced pressure. The residue was washed with Et2O (2 ×
10 mL) and pentane (2 × 20 mL), which afforded a yellow solid
(0.700 g, 90%). Anal. Calcd for C31H33B2F8N2O3P3Pd: C, 43.57;
H, 3.89. Found: C, 44.35; H, 4.41.
31P{1H} NMR (CDCl3): δ -11.1 (d, 2J(P,P) ) 21 Hz, PPh2), 28.1
2
(t, J(P,P) ) 21 Hz, PO). IR (KBr): νPdO ) 1247 (s) cms1
.
(Ph2P)2CHP(O)(OPh)2 (L2). This ligand was prepared according
to the same procedure as that described above for
(Ph2P)2CHP(O)(OMe)2, using MeP(O)(OPh)2 (1.890 g, 7.61 mmol),
n-BuLi (14.25 mL, 22.8 mmol, 1.6 M Aldrich), diisoprylamine
(2.490 g, 22.8 mmol), and PPh2Cl (3.350 g, 2.73 mL, 15.2 mmol).
It was obtained as a beige solid (3.370 g, 72%). Anal. Calcd for
C37H31O3P3: C, 72.08; H, 5.07. Found: C, 71.31; H, 5.11. 1H NMR
(CDCl3): δ 3.9 (1H, d, 2J(PO,H) ) 22.9 Hz, CH), 6.60-7.65 (30H,
[Pd{(Ph2P)2CHP(O)(OMe)2-P,P}2](BF4)2 (5). Solid (Ph2P)2-
CHP(O)(OMe)2 (0.400 g, 0.81 mmol) and [Pd(NCMe)4](BF4)2
(0.177 g, 0.81 mmol) were placed in a Schlenk flask and THF (20
mL) was added. The mixture was stirred at room temperature for
45 min, and the volatiles were removed under reduced pressure.
The residue was washed with Et2O (2 × 10 mL) and pentane (2 ×
20 mL), which afforded a gray solid (0.379 g, 75%). Anal. Calcd
for C54H54B2F8O6P6Pd: C, 51.28; H, 4.30. Found: C, 50.82; H, 5.00.
2
1H NMR (CDCl3): δ 3.32 (d, 6H, J(P,H) ) 11.5 Hz, POCH3),
2
m, aromatics). 31P{1H} NMR (CDCl3): δ -9.3 (d, J(P,P) ) 21.5
2
Hz, PPh2), 19.1 (t, 2J(P,P) ) 21.5 Hz, PO); IR (KBr): νPdO ) 1265
3.87 (d, 1H, J(P,H) ) 11.6 Hz), 7.15-7.82 (40H, m, aromatics).
31P{1H} NMR (CDCl3): δ -13.6 (d, 2J(P,P) ) 5.8 Hz, PPh2), 15.6
(s) cm-1
.
2
(t, J(P,P) ) 5.8 Hz, PO). IR (KBr): νPdO ) 1224 (s) cm-1
.
[Pd{(Ph2P)2CP(O)(OMe)2-P,P}2] (6a). Solid (Ph2P)2CHP-
(O)(OMe)2 (0.256 g, 0.52 mmol) and [Pd(µ-Cl)(dmba)]2 (0.291 g,
0.52 mmol) were placed in a Schlenk flask and THF (45 mL) was
added. The mixture was stirred at room temperature for 45 min,
and then the yellow solid precipitate was filtered (0.032 g, 6%).
Anal. Calcd for C54H52O6P6Pd: C, 59.54; H, 4.81. Found: C, 57.82;
(44) Chatt, J.; Vallarino, L. M.; Venanzi, L. M. J. Chem. Soc. 1957, 3413.
(45) (a) Rülke, R. E.; Ernsting, J. M.; Spek, A. L.; Elsevier, C. J.; van
Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769. (b)
Ladipo, F. T.; Anderson, G. K. Organometallics 1994, 13, 303.
(46) Kubas, G. J. Inorg. Synth. 1979, 19, 90.
(47) Sen, A.; Lai, T.-W. Inorg. Chem. 1984, 23, 3257.
(48) Wayland, B. B.; Schrammz, R. F. Inorg. Chem. 1969, 8, 971.
1634 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
H, 5.38. 1H NMR (CDCl3): δ 2.74 (d, 6H, 2J(P,H) ) 11.3 Hz, Me),
7.05-7.50 (40H, m, aromatics). 31P{1H} NMR (CDCl3): δ -31.4
20 mL) and dried under vacuum to give a yellow solid (1.10 g, 70%).
Anal. Calcd for C54H52NiO6P6 ·0.5 CH2Cl2: C, 60.39; H, 4.93. Found:
3
1
(s, PPh2), 25.6 (s, PO). IR (KBr): νPdO ) 1222 (s) cm-1
.
C, 60.09; H, 5.14. H NMR (CDCl3): δ 2.62 (d, 6H, J(P,H) ) 7.2
Hz, OCH3), 6.91-8.01 (40H, m, aromatics). 31P{1H} NMR (CDCl3):
δ -22.4 (s, PPh2), 23.1 (PO). IR (KBr): νPdO ) 1232 (s) cm-1. Mass
spectrum (ESI): 1041.13 (M+ + 1). Single crystals suitable for X-ray
diffraction were obtained by diffusion of pentane into a chloroform
solution of the complex.
[Pd{(Ph2P)2CP(O)(OPh)2-P,P}2] (6b). Solid (Ph2P)2CHP-
(O)(OPh)2 (0.300 g, 0.48 mmol) and [Pd(µ-Cl)(dmba)]2 (0.132 g,
0.24 mmol) were placed in a Schlenk flask and CH2Cl2 (30 mL)
was added. The mixture was stirred for 30 min, and the volatiles
were removed under reduced pressure. The residue was washed
with Et2O (2 × 15 mL) and pentane (2 × 20 mL), which afforded
a yellow solid (0.141 g, 33%). Anal. Calcd for C74H60O6P6Pd: C,
[Ni{(Ph2P)2CP(O)(OPh)2-P,P}2] (10b). Using a similar proce-
dure to that for 10a, solid [Ni(acac)2] (0.075 g, 0.29 mmol) was
added to a solution of (Ph2P)2CHP(O)(OPh)2 (0.360 g, 0.58 mmol)
in CH2Cl2 at ambient temperature. The reaction mixture was stirred
for 1 h, then the yellow solution was filtered and the volatiles were
removed under reduced pressure to give a yellow solid, which was
washed with diethylether (2 × 15 mL) and pentane (2 × 20 mL)
and dried under vacuum to yield a yellow solid (0.330 g, 90%).
Anal. Calcd for C74H60NiO6P6: C, 68.91; H, 4.69%. Found: C,
68.97; H, 4.77%. 1H NMR (CDCl3): δ 6.19-7.60 (60H, m,
aromatics). 31P{1H} NMR (CDCl3): δ -22.1 (s, PPh2), 12.3 (s, PO).
IR (KBr): νPdO ) 1244 (s) cm-1. Single crystals suitable for X-ray
diffraction were obtained by diffusion of pentane into a chloroform
or a dichloromethane solution of the complex.
1
66.45; H, 4.52. Found: C, 66.55; H, 5.35. H NMR (CDCl3): δ
6.5-8.1 (60H, m, aromatics). 31P{1H} NMR (CDCl3): δ -31.0 (s,
PPh2), 15.1 (s, PO). IR (KBr): νPdO ) 1246 (s) cm-1
.
[Pd(µ-Cl){(Ph2P)2CP(O)(OMe)2-P,P}]2 (7a). Solid [PdCl(Me)
(COD)] (0.215 g, 0.81 mmol) and (Ph2P)2CHP(O)(OMe)2 (0.400 g,
0.81 mmol) were placed in a Schlenk flask and CH2Cl2 (30 mL) was
added at ambient temperature. The yellow reaction mixture was stirred
for 1 h and the volatiles were removed under reduced pressure. The
residue was washed with Et2O (2 × 15 mL) and pentane (2 × 20
mL), which afforded a yellow solid (0.615 g, 60%). Anal. Calcd for
1
C54H52Cl2O6P6Pd2: C, 51.21; H, 4.14. Found: C, 51.05; H, 4.34. H
NMR (CDCl3): δ 2.98 (12H, d, 3J(PO,H) ) 11.5 Hz, OCH3),
7.24-7.97 (40H, m, aromatics). 31P{1H} NMR (CDCl3): δ -45.9 (s,
[NiCl2(Ph2P)2CHP(O)(OMe)2-P,P] (11a). CH2Cl2 (30 mL) was
added to a mixture of solid (Ph2P)2CHP(O)(OMe)2 (0.170 g, 2.37
mmol) and [NiCl2(DME)] (0.520 g, 2.37 mmol) in a 100 mL
Schlenk tube, and the mixture was stirred at room temerature for
1 h. The solution was filtered, and the volatiles were removed under
reduced pressure to give an ocre solid, which was washed with
diethylether (2 × 15 mL) and pentane (2 × 20 mL) and dried under
vacuum to give an ocre solid (0.710 g, 79%). Anal. Calcd for
C27H27Cl2NiO3P3 ·0.5CH2Cl2: C, 49.71; H, 4.25. Found: C, 49.70;
PPh2), 24.1 (s, PO). IR (KBr): νPdO ) 1229 (s) cm-1
.
[Pd(µ-Cl){(Ph2P)2CP(O)(OPh)2-P,P}]2 (7b). This complex was
prepared as described above for [Pd{(Ph2P)2CP(O)(OMe)2-P,P}(µ-
Cl)]2 from (Ph2P)2CHP(O)(OPh)2 (0.300 g, 0.48 mmol) and
[PdCl(Me)(COD)] (0.128 g, 0.48 mmol). It was obtained as a yellow
solid (0.429 g, 59%). Anal. Calcd for C74H60Cl2O6P6Pd2: C, 58.67,
H, 3.99. Found: C, 58.10; H, 4.49. 1H NMR (CDCl3): δ 6.53-7.91
(m, aromatics). 31P{1H} NMR (CDCl3): δ -45.0 (s, PPh2), 13.2
2
(s, PO). IR (KBr): νPdO ) 1194 (s) cm-1
.
H, 4.26. H NMR (CDCl3): δ 3.02 (d, 6H, J(P,H) ) 11.3 Hz),
1
[PdCl{(Ph2P)2CP(O)(OMe)2-P,P}{P(OPh)3}] (8). Pure P(OPh)3
(0.120 g, 0.38 mmol) was added to a solution of 7a (0.244 g, 0.19
mmol) in CH2Cl2 (20 mL). The mixture was stirred for 3 h, and
the volatiles were removed under reduced pressure. The residue
was washed with Et2O (2 × 10 mL) and pentane (2 × 20 mL),
which afforded a yellow solid (0.168 g, 94%). Anal. Calcd for
4.42 (m, 1H, PCHP), 7.26-8.50 (20H, m, aromatics). 31P{1H} NMR
(CDCl3): δ -34.5 (d, J(P,P) ) 16 Hz, PPh2), 25.6 (t, J(P,P) )
16 Hz, PO). IR (KBr): νPdO ) 1241 (s) cm-1.
2
3
[NiCl2(Ph2P)2CHP(O)(OPh)2-P,P] (11b). CH2Cl2 (40 mL) was
added to a mixture of solid (Ph2P)2CHP(O)(OPh)2 (0.750 g, 1.21
mmol) and [NiCl2(DME)] (0.267 g, 1.21 mmol) in a 100 mL
Schlenk tube and the mixuture was sitrred at room temperature
overnight. The solution was filtered and the volatiles were removed
under reduced pressure to give an ocre solid, which was washed
with diethylether (2 × 15 mL) and pentane (2 × 20 mL) and dried
under vacuum to afford an ocre solid (1.220 g, 82%). Anal. Calcd
for C37H31Cl2NiO3P3: C, 59.56; H, 4.19. Found: C, 60.67; H, 4.82.
1H NMR (CDCl3): δ 3.48 (m, 1H, PCHP), 6.24-8.59 (30H, m,
1
C45H41ClO6P4Pd: C, 57.28; H, 4.38. Found: C, 56.91; H, 4.63. H
NMR (CDCl3): δ 2.95 (d, 6H, 3J(PO,H) ) 12 Hz, OCH3),
6.85-7.99 (35H, m, aromatics). 31P{1H} NMR (CDCl3): δ -49.4
(dd, 2J(P,P) ) 75 Hz, 2J(P,P)trans ) 644 Hz, PPh2 trans to P(OPh)3),
-39.8 (dd, 2J(P,P) ) 75 Hz, 2J(P,P)cis ) 28 Hz, PPh2 cis to
P(OPh)3), 24.6 (d, 4J(P,P) ) 19 Hz, P ) O), 110.0 (ddd, 2J(P,P)trans
) 644 Hz, 2J(P,P)cis ) 28 Hz, 4J(P,P) ) 19 Hz, P(OPh)3). IR (KBr):
νPdO ) 1221 (s) cm-1
.
aromatics). 31P{1H} NMR (CDCl3): δ -34.2 (d, J(P,P) ) 16.7,
2
3
[Cu2{(Ph2P)2CHP(O)(OMe)2}2](BF4)2 (9). Solid [Cu(NCMe)4]-
(BF4) (0.250 g, 0.79 mmol) and (Ph2P)2CHP(O)(OMe)2 (0.389 g,
0.79 mmol) were placed in a Schlenk flask and CH2Cl2 (20 mL)
was added. The mixture was stirred for 2 h, and the volatiles were
removed under reduced pressure. The residue was washed with Et2O
(2 × 20 mL) and pentane (2 × 20 mL), which afforded a white
solid. Anal. Calcd for C54H54B2Cu2F8O6P6: C, 50.45; H, 4.23.
Found: C, 49.5; H, 4.43. 1H NMR (CDCl3): δ 2.35 (br, 12H, OCH3),
3.75 (br, 2H, CH), 7.23-7.82 (40H, aromatics). 31P{1H} NMR
(CDCl3): δ 1.4 (br, PPh2), 28.0 (vbr, PO). IR (KBr): νPdO ) 1247
PPh2), 7.24 (t, J(P,P) ) 16.7, PO). IR (KBr): νPdO ) 1270 (s)
cm-1
.
[Ni{(Ph2P)2CC(O)NPh2-P,P}2] (13). THF (20 mL) was added
at ambient temperature to a mixture of (Ph2P)2CHC(O)NPh2 (92.75
g, 0.16 mmol) and [Ni(acac)2] (0.045 g, 0.08 mmol) in a 100 mL
Schlenk tube. The reaction mixture was stirred for 1 h, the green
solution was filtered, the solvent was removed under reduced
pressure, and the solid was extracted in CH2Cl2. Solvent evaporation
under reduced pressure afforded a green solid (0.022 g, 44%). Anal.
Calcd for C76H60N2NiO2P4: C, 75.07; H, 4.97; N, 2.22. Found: C,
(s) cm-1, νPdOCu ) 1182 (s) cm-1
.
74; H, 4.57 N, 1.47. H NMR (CDCl3): δ 6.12-7.92 (60H, m,
1
[Ni{(Ph2P)2CP(O)(OMe)2-P,P}2] (10a). Solid [Ni(acac)2]·H2O
(0.410 g, 1.52 mmol) was added to a solution of (Ph2P)2CHP(O)(OMe)2
(1.500 g, 3.05 mmol) in CH2Cl2 at ambient temperature. The reaction
mixture was stirred for 1 h, then the solution was filtered and the
volatiles were removed under reduced pressure to give a yellow solid,
which was washed with diethylether (2 × 15 mL) and pentane (2 ×
aromatics). 31P{1H} NMR (CDCl3): δ -28.6 (s, PPh2). IR (KBr):
νPdO ) 1652 (s) cm-1
.
[Ni{Ph2PC(Ph)P(O)(OEt)2-P,O}2] (15). Solid [Ni(acac)2]·H2O
(0.410 g, 1.85 mmol) was added to a solution of (Ph2P)CH(Ph)-
P(O)(OEt)2 (1.52 g, 3.7 mmol) in CH2Cl2 (30 mL) at ambient
temperature. The reaction mixture was stirred for 1 h, then the solution
Inorganic Chemistry, Vol. 48, No. 4, 2009 1635

Hamada and Braunstein
Table 8. Crystal Data and Details of the Structure Determinations for the Palladium Complexes 2a, 2b, 6a·2CH2Cl2, 6b, 7a and 7b
2a
2b
6a ·2CH2Cl2
6b
7a
7b
formula
Mr
crystal system
space group
a (Å)
C27H27Cl2O3P3Pd
669.70
monoclinic
P21/c
10.9438(6)
16.4162(11)
16.8743(7)
90
114.693(3)
90
C37H31Cl2O3P3Pd
793.83
monoclinic
P21/c
10.4790(10)
15.764(2)
20.732(3)
90
97.21(5)
90
C54H52O6P6Pd, 2(CH2Cl2) C74H60O6P6Pd
C54H52Cl2O6P6Pd2
1266.48
C74H60Cl2O6P6Pd2
1514.74
monoclinic
P21/n
10.5160(10)
19.337(2)
16.642(2)
90
90.64 (5)
90
3383.9(6)
2
1259.03
triclinic
P1
1337.44
monoclinic
P21/c
triclinic
j
j
P1
9.8929(2)
11.7832(3)
24.8050(6)
83.8140(10)
88.885(2)
80.004(2)
2831.04(11)
2
12.3080(2)
21.6970(3)
24.3410(4)
90
100.00(6)
90
9.8880(10)
14.344(3)
19.349(4)
102.815(5)
94.658(5)
90.533(5)
2666.1(8)
2
b, (Å)
c(Å)
R (°)
ꢀ (°)
γ (°)
V (Å3)
Z
2754.4(3)
4
1.615
3397.7(7)
4
1.552
6401.43(17)
4
Dx (Mg m-3
)
1.477
1.388
1.578
1.00
1.487
0.81
µ (mm-1
)
1.07
0.88
0.74
0.49
crystal size (mm)
Rint
0.30 × 0.20 × 0.10 0.10 × 0.10 × 0.10 0.30 × 0.25 × 0.15
0.10 × 0.10 × 0.10 0.10 × 0.10 × 0.10 0.10 × 0.10 × 0.10
0.053
27.5
0.122
0.053
0.048
0.0000
0.0000
θmax (°)
27.6
30.1
30.1
35.0
35.0
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.079, 1.04
0.083, 0.149, 1.14
0.80, -0.76
0.050, 0.134, 0.97
1.22, -1.49
0.046, 0.119, 1.05
0.66, -1.42
0.071, 0.147, 0.85
1.90, -0.73
0.045, 0.108, 0.90
0.66, -1.40
F
max, Fmin (e Å-3
)
0.44, -0.66
Table 9. Crystal Data and Details of the Structure Determinations of the Nickel Complexes 10a,b and 11a·CHCl3
10a·4CHCl3
10b·4CHCl3
11a·CHCl3
formula
Mr
C54H52NiO6P6, 4(CHCl3)
1518.96
C74H60NiO6P6, 4(CHCl3)
1767.22
C27H27Cl2NiO3P3, CHCl3
741.37
crystal system
space group
a (Å)
b (Å)
c (Å)
Triclinic
P1
Triclinic
P1
Triclinic
P1
j
j
j
10.2810(5)
11.8690(5)
14.9440(10)
81.1620(14)
77.9320(16)
76.1380(14)
1720.98(16)
1
11.3934(2)
15.7103(4)
24.1342(6)
107.948(1)
95.481(1)
94.839(2)
4061.22(16)
2
10.7000(3)
16.4637(3)
19.4248(5)
97.557(1)
97.688(1)
105.517(10)
3217.00(14)
4
R (°)
ꢀ (°)
γ (°)
V (Å3)
Z
Dx (Mg m-3
)
1.466
0.93
1.445
0.80
1.531
1.20
µ (mm-1
)
crystal size (mm)
Rint
0.14 × 0.12 × 0.10
0.30 × 0.20 × 0.15
0.50 × 0.40 × 0.30
0.035
0.066
0.044
θmax (°)
30.2
27.5
30.0
R[F2 >2σ(F2)], wR(F2), S
0.072, 0.200, 1.03
1.69,-1.21
0.072, 0.190, 1.03
1.12,-1.11
0.044, 0.115, 1.07
0.85,-0.81
F
max, Fmin (e Å-3
)
was filtered and the volatiles were removed under reduced pressure to
give a green solid, which was washed with diethylether (2 × 15 mL)
and pentane (2 × 20 mL) and dried under vacuum to give a pale green
solid (1.10 g, 70%). Anal. Calcd for C46H50NiO6P4: C, 62.68; H, 5.72.
Found: C, 59.25; H, 6.05. 31P{1H} NMR (CDCl3): δ -5.8 (br s, PPh2),
27.4 (br s, PO). IR (KBr): νPdO ) 1251 (s) cm-1. Mass spectrum (ESI):
m/z 883.21 [M+ + H].
Crystal Structure Determinations. Crystals suitable for X-ray
diffraction were obtained by slow diffusion of hexane or pentane
into a dichloromethane solution of the complex at 5 °C. Diffraction
data were collected on a Kappa CCD diffractometer using graphite-
monochromated Mo KR radiation (λ ) 0.71073 Å) (Tables 8 and
9). Data were collected using ꢁ-scans and the structures were solved
by direct methods using the SHELX 97 software and the refinement
was by full-matrix least-squares on F2.51,52 No absorption correction
was used. All non-hydrogen atoms were refined anisotropically with
12 Union Road, Cambridge CB2 1EZ, U.K. (fax: (+44)1223-336-
033; e-mail: deposit@ccdc.cam.ac.uk).
Oligomerization of Ethylene. All catalytic tests were started
between 25 and 30 °C, and no cooling of the reactor was done
during the reaction. After injection of the catalytic solution and of
the cocatalyst under a constant low flow of ethylene, the reactor
was pressurized to 10 bar. A temperature increase was observed
that resulted solely from the exothermicity of the reaction. The 10
bar working pressure was maintained during the experiments
through a continuous feed of ethylene from a reserve bottle placed
on a balance to allow continuous monitoring of the ethylene uptake.
At the end of each test (35 min), a dry ice bath was used to rapidly
cool down the reactor, thus stopping the reaction. An ice bath was
then used and when the inner temperature reached 0 °C, the ice
bath was removed allowing the temperature to slowly rise to 10
°C. The gaseous phase was then transferred into a 10 L polyethylene
tank filled with water. An aliquot of this gaseous phase was
transferred into a Schlenk flask, previously evacuated, for GC
analysis. The products in the reactor were hydrolyzed in situ by
the addition of ethanol (10 mL), transferred into a Schlenk flask,
and separated from the metal complexes by trap-to-trap evaporation
(20 °C, 0.8 mbar) into a second Schlenk flask previously immersed
in liquid nitrogen in order to avoid any loss of product.
H atoms introduced as fixed contributors (dC-H ) 0.95 Å, U11
)
0.04). Crystallographic data (excluding structure factors) have been
deposited in the Cambridge Crystallographic Data Centre as
Supplementary publication n° CCDC 705823-705831. Copies of
the data can be obtained free of charge on application to CCDC,
(49) Cope, A. C.; Friedrich, E. C. J. Am. Chem. Soc. 1968, 90, 909.
(50) Cotton, F. A. Inorg. Synth. 1971, 13, 160.
(51) Kappa CCD Operation Manual; Nonius BV, D.: The Nederland.
(52) Sheldrick, G. M. SHELXL97, Program for the refinement of crystal
structures; University of Go¨ttingen: Germany, 1997.
With AlEtCl2 (Table 6), 4 × 10-5 mol of Ni complex were
dissolved in cholorobenzene and injected into the reactor under an
ethylene flux. Then a cocatalyst solution corresponding to 3, 6, 10,
1636 Inorganic Chemistry, Vol. 48, No. 4, 2009

Bis(diphenylphosphino)methane-Phosphonate Ligands
or 14 equiv was added to form a total volume of 15 mL with the
precatalyst solution.
la Recherche. We are grateful to Drs. L. Brelot and A.
DeCian and Professor R. Welter (ULP Strasbourg) for the
resolution of the crystal structures, to Dr. X. Morise for his
contribution, and to M. Mermillon-Fournier for technical
assistance.
With MAO (Table 7), 4 × 10-5 mmol of Ni complex was
dissolved in chlorobenzene and injected into the reactor under an
ethylene flux. Then a cocatalyst solution corresponding to 100, 200,
or 400 equiv of MAO respectively, was added to form a total
volume of 20 mL with the precatalyst solution.
Supporting Information Available: Crystallographic details for
all structures in the form of CIF files. This material is available
free of charge via the Internet at http://pubs.acs.org.
Acknowledgment. Dedicated to Professor Richard J.
Puddephatt for his numerous and outstanding contributions
to inorganic and organometallic chemistry. This work was
supported by the Centre National de la Recherche Scienti-
fique and the Ministe`re de l’Enseignement Supe´rieur et de
IC8020436
Inorganic Chemistry, Vol. 48, No. 4, 2009 1637