2-Dialkyl- and 2-tert-butylphenylphosphinophenol(ate) nickel and palladium complexes: Control of E/Z-configuration in bis(P∩O --chelates) and activation of the nickel complexes for polymerization of ethylene

Article abstract of DOI:10.1002/zaac.200400003

Nickel bis(2-dialkylphosphinophenolates), detected as the spent form of organonickel 2-dialkylphosphinophenolate catalysts for the polymerization of ethylene, were studied. In contrast to the impact of the P-basicity on the catalyst properties, the configuration of bis(2-dialkylphosphinophenolate) nickel is controlled only by steric effects. Small alkyl substituents favor, as do phenyl groups, square planar cis-bis(P^∩O^--chelates) while more bulky alkyl groups lead to trans-isomers. Dicyclohexyl- and tert-butylphenylphosphino groups give rise to borderline cases. Analogous palladium complexes show a slightly smaller effect of the metal size on the cis/trans-control. Intermediates on the way to Pd^II bis(P ^∩O^--chelates), trans-dichloro-bis(phosphinophenol)- and chlorophosphinophenol phosphinophenolate palladium(II) complexes could be isolated; the crystal structure of one of the latter was determined. The nickel bis(2-dialkylphosphinophenolates) can be activated as polymerization catalysts, to a limited extent by NiBr2·DME and sodium hydride or triethylsilane in THF, more efficiently by nBuLi or nBuLi/NiBr₂·DME.

Full text of DOI:10.1002/zaac.200400003

2-Dialkyl- and 2-tert-Butylphenylphosphinophenol(ate) Nickel and Palladium
Complexes: Control of E/Z-Configuration in Bis(PʝO؊-chelates) and Activation
of the Nickel Complexes for Polymerization of Ethylene
Joachim Heinicke*,a, Martin Köhlera,b, Normen Peuleckea, Wilhelm Keimb, and Peter G. Jonesc
a Greifswald, Institut für Chemie und Biochemie, Ernst-Moritz-Arndt-Universität
b Aachen, Institut für Technische Chemie und Petrolchemie, Rheinisch-Westfälische Technische Hochschule
c Braunschweig, Institut für Anorganische und Analytische Chemie der Technischen Universität
Received January 14th, 2004.
Professor Reinhard Schmutzler zum 70. Geburtstag gewidmet
Abstract. Nickel bis(2-dialkylphosphinophenolates), detected as the
spent form of organonickel 2-dialkylphosphinophenolate catalysts
for the polymerization of ethylene, were studied. In contrast to the
impact of the P-basicity on the catalyst properties, the configura-
tion of bis(2-dialkylphosphinophenolate) nickel is controlled only
by steric effects. Small alkyl substituents favor, as do phenyl groups,
square planar cis-bis(PʝOϪ-chelates) while more bulky alkyl
groups lead to trans-isomers. Dicyclohexyl- and tert-butylphe-
nylphosphino groups give rise to borderline cases. Analogous pal-
ladium complexes show a slightly smaller effect of the metal size on
the cis/trans-control. Intermediates on the way to PdII bis(PʝOϪ-
chelates), trans-dichloro-bis(phosphinophenol)- and chloro-
phosphinophenol phosphinophenolate palladium(II) complexes
could be isolated; the crystal structure of one of the latter was
determined. The nickel bis(2-dialkylphosphinophenolates) can be
activated as polymerization catalysts, to a limited extent by
NiBr2·DME and sodium hydride or triethylsilane in THF, more
efficiently by nBuLi or nBuLi / NiBr2·DME.
Keywords: O,P Ligands; Nickel; Chelate complexes; Coordination
modes; Polymerization; Homogenous catalysis
2-Dialkyl- und 2-tert-Butylphenylphosphinophenol(ate) Nickel und Palladium
Komplexe: Kontrolle der E/Z-Konfiguration in Bis(PʝO؊-chelat)en und Aktivierung
der Nickel Komplexe für die Polymerisation von Ethylen
Inhaltsübersicht. Nickel(II)-bis(2-dialkylphosphinophenolate), Des-
aktivierungsprodukte von Organonickel(II) bis(2-dialkylphosphi-
nophenolat)-Polymerisationskatalysatoren, wurden untersucht. Im
Gegensatz zum Einfluß der P-Basizität auf die Katalysatoreigen-
schaften ist für die Konfiguration der Nickel-bis(2-dialkylphosphi-
nophenolate) nur der sterische Einfluß der P-Substituenten wesent-
lich. Kleine Alkylreste (Ethyl) begünstigen ähnlich Phenylgruppen
quadratisch-planare cis-Bis(PʝOϪ-chelate) während sterische Hin-
derung durch Isopropyl- oder tert-Butylreste zu trans-Isomeren
führt. Dicyclohexyl- und tert-Butylphenylphosphinogruppen
stellen Grenzfälle dar. Analoge Palladium(II)-Komplexe zeigen be-
züglich der cis/trans-Kontrolle nur marginale Unterschiede zum
Nickel(II). Zwischenstufen der Bildung der PdII bis(PʝOϪ-chelate),
trans-Dichloro-bis(phosphinophenol)- und Chloro(phosphinophe-
nol)(phosphinophenolat)-palladium(II)-Komplexe, konnten isoliert
und in einem Falle durch Kristall- und Molekülstruktur charakteri-
siert werden. Nickel(II)-bis(2-dialkylphosphinophenolat)e können
zu Polymerisationskatalysatoren aktiviert werden, mit Einschrän-
kungen durch NiBr2·DME und Natriumhydrid oder durch Tri-
ethylsilan in THF, effizienter durch nBuLi oder nBuLi
/
NiBr2·DME.
Introduction
discovery of novel types of nickel and other late transition
metal complex catalysts leading to branched polymers or
improved tolerance towards functional groups and protic
solvents [2Ϫ6]. In the course of continuous investigations
on 2-phosphinophenols, O- and/or P-substituted derivatives
and various nickel complexes thereof [7Ϫ12], we studied
organonickel phosphinophenolate oligo- and polymeriz-
ation catalysts [10Ϫ12] and observed by 31P NMR the for-
mation of nickel bis(phosphinophenolate) chelate com-
plexes as the spent form of the catalysts when the ethylene /
catalyst ratio was low [12]. The diphenylphosphino complex
cis-[Ni(2-Ph2PC6H4O)2] [13] was found to be (re)activated
by heating in toluene in the presence of ethylene,
Nickel chelate complexes, important industrial catalysts in
the oligomerization of ethylene by the Shell Higher Olefin
Process [1], have recently enjoyed a renaissance by the
* Prof. Dr. J. Heinicke
Institut für Chemie und Biochemie
Ernst-Moritz-Arndt-Universität Greifswald
Soldmannstr. 16
D-17487 Greifswald, Germany
Fax: (ϩ49 3834) 864319
E-mail: heinicke@uni-greifswald.de
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J. Heinicke, M. Köhler, N. Peulecke, W. Keim, P. G. Jones
NiCl2·DME and sodium hydride and to give higher turn-
over numbers and molecular weights than catalysts formed
from methallylnickel diphenylphosphinophenolate or, in
situ, from Ni(1,5-COD)2 and diphenylphosphinophenol
[12]. Analogous cis-bis(dialkylphosphinophenolate) nickel
complexes had been unknown, and only after completion
of the paper a first representative (alk ϭ C2H4OC2H5)
was reported [14]. The known isomers, trans-[Ni(2-iPr2P-
4,6-tBu2C6H2O)2] [11] and trans-[Ni(2-tBu2PC6H4O)2]
[15], could not be activated in the way found for
cis-[Ni(2-Ph2PC6H4O)2]. Considering that dialkylphosphino-
phenolate nickel catalysts (2-R2PC6H4ONiRЈ) give poly-
ethylenes with much higher molecular weights than di-
Reaction of 1a؊f with sodium tetrachloropalladate
in methanol led to trans-[bis(phosphinophenol)PdCl2]
complexes 3, pure in case of 3a and 3c, or mixtures with
trans-[(phosphinophenol)(phosphinophenolate)PdCl] 4. The
isolated complexes 3a and 3c were converted to the pal-
ladium(II) bis(dialkylphosphinophenolates) 5a and 5c by
treatment with sodium carbonate. The mixtures formed
from 1b or 1d؊f were heated under vacuum. This led
to enrichment of the bis(chelates) 5b or 5d؊f. Cis-5b was
obtained in spectroscopically pure form by vacuum subli-
mation while addition of base was required to isolate pure
5d؊f (eq. (2)). It should be mentioned that 5b as generated
by vacuum sublimation is the cis-form, while 5b synthesized
at room temperature in presence of Na2CO3 is the trans-
isomer (kinetic product) which at room temperature slowly
converts to the cis-form (thermodynamic product). Apart
from the palladium(II) bis(dialkylphosphinophenolates)
5a؊e, the tert-butylphenylphosphinophenolate 5f was in-
cluded in the investigation for comparison with related
P-substituted nickel complexes (see discussion below).
phenylphosphinophenolate catalysts [12],
a somewhat
broader knowledge of nickel bis(dialkylphosphinophenol-
ates) seemed desirable to us. Therefore, we prepared some
nickel and, for more general conclusions, analogous pal-
ladium complexes of this type, studied the structure of the
bis(chelates) and PdCln-phosphinophenol(ate) precursor
complexes (n ϭ 1,2) and the possibility of using the nickel
bis(dialkylphosphinophenolates) for catalyst generation;
here we report on the results.
Structure elucidation and discussion
Bis(2-phosphinophenol)- and mixed phosphinophenol-
phosphinophenolate complexes.
Results and Discussion
Bis(2-phosphinophenol)- or mixed phosphinophenol-phos-
phinophenolate complexes of nickel(II) are unknown; to the
best of our knowledge, only a 2-phosphinophenol Ni(0)
complex has been reported [9]. The softer palladium(II),
however, forms more stable bis(2-phosphinophenol) dihal-
ides [15, 16] allowing isolation of the P-dialkyl derivatives
3a and 3c in pure form. The coordination at the phosphorus
atom is established by the downfield phosphorus coordi-
nation shift (∆δ ϭ 61.5, 52.5) and the multiplicity of the
13C NMR signals of the carbon nuclei directly bound to
phosphorus atom while the appearance of OH in the nor-
mal range (δ ϭ 8 to 9) and the relatively constant signals
of C-1 (connected to the OH group) indicate lack of coordi-
Preparation of the complexes
The new bis(2-dialkylphosphinophenolate) nickel(II) and
palladium(II) complexes were synthesized by known routes.
2-Dialkylphosphinophenols 1a and 1b, respectively, were
heated with the semimolar amount of nickelocene in tolu-
ene at 80 to 110 °C to furnish the corresponding nickel
bis(2-dialkylphosphinophenolates). The diethyl derivative
2a forms orange, the dicyclohexyl derivative 2b green mic-
rocrystals (eq. (1)). Intermediate cyclopentadienylnickel
phosphinophenolates, known for 2-diphenyl-[13] and
2-alkylphenylphosphinophenolates [10], react readily with
excess 1a or 1b and have not been observed.
1
nation at the oxygen atom. Similar JPC-2 coupling con-
stants in 3a,c and 5c suggest the trans-configuration
whereas 1JPC-2 of cis-5a is larger. 3b, 3d and 3f are less stable
and undergo partial deprotonation even in the absence of
an auxiliary base, but were detected by characteristic 31P
NMR signals (δ31P ϭ 17.8, 13.9 and 34.0), which differ
from those of PʝOϪ-chelates (see below) in their smaller
coordination chemical shift (∆δ ϭ 51.5, 47.3, 51.5). The
deprotonation products, the trans-monochelates 4b (δ31P ϭ
2
2
12.4, 59.7, JPP ϭ 436 Hz), 4d (δ31P ϭ 13.9, 60.9, JPP
ϭ
425 Hz) and 4f (δ31P ϭ 33.5, 56.0, JPP ϭ 438 Hz), were
detected in the crude product mixtures by phosphorus dou-
blets typically for P-only and PʝOϪ-chelate coordination,
with two-bond PϪPdϪP coupling constants characteristic
for trans-configuration. Single crystals of 4d allowed a de-
tailed analysis of the molecular structure (Figure 1, Tables
1, 2). PdII complexes of type 4 are yet unknown to our
knowledge. 4d forms a distorted square but planar structure
(average deviation of Pd, Cl, O1, P1, P2 from the plane
2
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2-Dialkyl- and 2-tert-Butylphenylphosphinophenol(ate) Nickel and Palladium Complexes
˚
0.02 A) around the palladium(II) atom. The distortions are
associated with the rather small P1ϪPdϪO1 angle (84.06°)
of the rigid five-membered ring, which enforces an increase
of the angles O1ϪPdϪP2, ClϪPdϪP2 and ClϪPdϪP1.
The chelate ring is planar (average deviation from the best
shown in Figure 1. The overall structure is however a race-
mate. Some short CϪH···O and CϪH···Cl contacts could
be interpreted as weak hydrogen bonds (Table 2).
˚
Table 1 Selected bond lengths/A and angles/°.
˚
plane 0.03 A). The arrangement of the phosphinophenol
Pd-O(1)
Pd-P(1)
Pd-Cl
Pd-P(2)
P(1)-C(11)
P(1)-C(21)
1.9972(16)
2.2821(6)
2.2952(6)
2.4228(6)
1.805(2)
P(1)-C(51)
P(2)-C(41)
P(2)-C(31)
P(2)-C(55)
O(1)-C(12)
O(2)-C(32)
1.870(3)
1.828(2)
1.848(2)
1.874(3)
1.344(3)
1.354(3)
ring (interplanar angle 27° to the chelate ring) is controlled
by the hydrogen bond between the hydroxyl group and the
phenolate oxygen atom. The two bulky tert-butyl groups are
in anti-positions (dihedral angle C51ϪP1···P2ϪC55 Ϫ156°)
causing S-configuration of both P1 and P2 in the molecule
1.816(3)
O(1)-Pd-P(1)
O(1)-Pd-Cl
P(1)-Pd-Cl
O(1)-Pd-P(2)
P(1)-Pd-P(2)
Cl-Pd-P(2)
C(11)-P(1)-C(21)
C(11)-P(1)-C(51)
C(21)-P(1)-C(51)
C(11)-P(1)-Pd
84.06(5)
176.65(5)
92.60(2)
91.13(5)
174.82(2)
92.21(2)
107.17(12)
106.85(11)
111.10(12)
99.51(8)
C(21)-P(1)-Pd
C(51)-P(1)-Pd
C(41)-P(2)-C(31)
C(41)-P(2)-C(55)
C(31)-P(2)-C(55)
C(41)-P(2)-Pd
C(31)-P(2)-Pd
C(55)-P(2)-Pd
C(12)-O(1)-Pd
116.36(8)
114.46(8)
101.75(11)
110.26(11)
103.87(12)
108.76(8)
122.80(8)
108.91(9)
120.69(15)
Bis(phosphinophenolate) complexes.
1H and 13C NMR and analytical data of 2a,b and 5a؊f
are in accordance with the bis(PʝOϪ-chelate) structure, the
diamagnetism of the nickel(II) complexes indicating a
square-planar configuration around the metal. The chemi-
cal equivalence of the two phosphorus atoms prevents the
assignment of cis- or trans-isomers as for 4 simply by their
Figure 1 Molecular structure of 4d (ellipsoids with 50 % probabi-
lity).
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J. Heinicke, M. Köhler, N. Peulecke, W. Keim, P. G. Jones
a)
˚
Table 2 Hydrogen bonds/A and °
Table 3 Selected NMR data of square-planar cis- and trans-bis-
(phosphinophenolate) nickel(II) and palladium(II) complexes 2
and 5 and of trans-bis(phosphinophenol)PdCl2 3 (∆δ ϭ δcomplex-δ1)
D-H···A
d(D-H)
d(H···A)
d(D···A)
<(DHA)
O(2)-H(02)···O(1)
0.86(4)
0.98
0.98
0.95
0.95
1.63(4)
2.45
2.65
2.98
2.94
2.490(3)
3.319(5)
3.457(4)
3.678(2)
3.820(3)
175(4)
147.0
140.4
131.3
155.0
compd. (solv.) ∆δ31
P
∆δ13C-1 NP-C2-P (Hz) NP-C1-P (Hz) NP-C6-P (Hz)
C(58)-H(58C)···O(2)
C(53)-H(53C)···O(2)#1
C(14)-H(14)···Cl#2
C(24)-H(24)···Cl#3
a)
cis-2a
cis-2b
85.6
79.2
61.6
14.0
12.7
17.5
17.1
55.8
53.0
41.2
42.6
15.6
15.0
32
12.9
11.3
6.9
a)
b)
b)
trans-2b
trans-2e [11] 62.0
30.5
7.4
a) Symmetry transformations used to generate equivalent atoms: #1 Ϫx,
yϪ1/2, Ϫzϩ3/2; #2 xϪ1, y, z; #3 Ϫxϩ1, Ϫyϩ1, Ϫzϩ2.
a)
cis-5a
cis-5b
cis-5f
95.2
92.5
76.9
15.3
16.4
15.8
51.6
48.9
50.5
11.6
10.7
12
17.1
17.1
17.3
b)
a)
a)
b)
trans-5c
trans-5b
trans-5e
trans-5d
trans-5f
76.2
79.1
80.5
82.1
60.3
17.4
19.0
19.6
17.6
38.7
39.2
39.7
38.7
24.7
25.4
24.5
25.0
10.6
10.6
10.5
10.4
characteristic two-bond P-MII-P coupling constants. The
different nature of linear P-MII-O (cis) or P-MII-P and
O-MII-O (trans) substructures, however, influence the
chemical shifts of phosphorus and 13C-1 and the P-C coup-
ling constants of the carbon nuclei C-1, C-2 and C-6 in a
way that distinguishes between the two configurations.
Characteristic differences are compiled in Table 3.
b)
a)
a,d)
c)
c)
trans-3a
trans-3c
61.5
52.5
Ϫ1.6
Ϫ1.5
43.5
40.7
0
4.4
0
0
a) in CDCl3, b) in C6D6, c) in D8-THF, d) minor isomer, Յ 5 %.
Typically, the phosphorus coordination chemical shifts
∆δ(31P) of the cis-isomers are larger than those of the trans-
isomers (∆δcis-trans ϭ 13Ϫ18) indicating stronger deshielding
and donor character of phosphorus. This suggests that the
cis- differ from the trans-isomers by some push(P)-pull(O)
bonding character within the nearly linear P-MII-O sub-
structure. In this sense MII acquires more electron density
from phosphorus, which in turn reduces the electron with-
drawal from OϪ and C-1, indicated by the somewhat lower
coordination chemical shift ∆δ(13C) of C-1 in the cis- as
compared to the trans-isomers (∆δcis-trans ϭ Ϫ3 to Ϫ5).
If, as typically, only one isomer is formed, the ∆δ(31P)
value is less indicative, since it depends apart from the con-
figuration also on the nature of the phosphorus substituents
and the metal and is larger for dialkyl- than for alkylphenyl-
and diphenylphosphino groups (e.g. ∆δ ϭ 85.6, 75.1, 65.0
for cis-2a, cis-[Ni(2-iPrPhP-4-MeC6H3O)2], cis-[Ni(2-Ph2P-
4-MeC6H3O)2] [10]) and for palladium than for analogous
nickel complexes (cf. 2a,b,e and 5a,b,e). However, an unam-
biguous distinction of cis- and trans-isomers is possible in
terms of the different coupling constants N ϭ ΗJϩJЈΗ of the
nuclei 13C-1, 13C-2 and 13C-6 with the two phosphorus nu-
clei. In most cases three of the expected five lines (X part
of ABX; A and B phosphorus adjacent to 12C and 13C)
can be observed. N, the difference of the outer lines of the
pseudotriplet (τ), is larger for C-2 (by 20Ϫ30 %) and C-6
(by 60Ϫ70 %) in the cis- than in the trans-configuration
while for C-1 the opposite is found (Ntrans ഠ 2Ncis).
more stable in C6D6 and CDCl3. Additional tert-butyl
groups in 4- and 6-position in 5e steer the preference to the
trans-isomer. The preference for the cis-configuration not
only in NiII or PdII bis(2-diphenylphosphinophenolates)
[9, 15, 17] but also in 2a and 5a and the possible or even
preferred cis-configuration of 2b or 5b, which has even
more basic phosphino groups than 2a and 5a (for basicity
of aryl- and alkylphosphines see [18]) provide evidence that
the configuration is not controlled by the basicity of the
phosphino groups but only by steric factors as previously
suggested, but not proved. The lower stability of the trans-
configuration in 5b as compared to 2b is due to the larger
size of PdII as compared to the NiII atom, which lowers
steric strain by the ligands, while the increased steric stress
in 5e by tert-butyl groups in 4- and particularly in 6-posi-
tion turns the preferred configuration again to trans.
A similar borderline behavior as caused by dicyclohexyl
groups was found earlier for tert-butylphenylphosphino
groups. While rac-[Ni(2-iPrPhP-4-MeC6H3O)2] [10] as well
as meso-[Ni(2-iPrPhP-4,6-tBu2C6H2O)2] [9] crystallize as
cis-isomers, the somewhat bulkier [Ni(2-tBuPhP-4-
MeC6H3O)2] forms meso-trans-isomers [10]. [Ni(2-tBuPhP-
4,6-tBu2C6H2O)2] (2f) displays trans-configuration in
D8-THF solution but crystallizes as distorted rac-cis-iso-
mers [9]. The angle between the best planes of the five-
membered rings increases from 11.3° in meso-[Ni(2-iPrPhP-
4,6-tBu2C6H2O)2] to 22.3° in 2f and thus indicates the labile
configuration. 5f, prepared for comparison, prefers the cis-
configuration in C6D6 and in CDCl3 solution (cis to trans
each 94:6 %) and thus shows the same effect as 5b, a shift
towards the cis-configuration by increasing size of the metal
ion in borderline cases. Finally, it should be mentioned that
2-bis(2,4,6-trimethoxyphenyl)phosphino-3,5-dimethoxy-
phenolate ligands, highly P-basic and bulky, also form a
trans-bis(PʝOϪ-chelate) complex [19]. In non-anellated
The structure elucidation of the bis(2-dialkylphosphino-
phenolates) 2a,b and 5a؊e shows that diethylphosphino
groups give rise to cis-configuration while diisopropyl
groups, like di-tert-butyl phosphino groups [15], lead to for-
mation of trans-isomers. Dicyclohexylphosphino groups al-
low both cis- and trans-configuration. 2b adopts the trans-
form in the crystal (as seen by the green color [11, 15]) and
in C6D6 solution but favors the cis-form (90:10 %) in CDCl3
solution. 5b, as mentioned above, can be obtained as the
trans-isomer but rearranges into the cis-isomer, which is
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2-Dialkyl- and 2-tert-Butylphenylphosphinophenol(ate) Nickel and Palladium Complexes
phosphinoenolate complexes the unsaturated C-C-back-
bone is somewhat less rigid and allows nickel bis(2-diiso-
propylphosphino-1-phenyl-enolate) to adopt both the cis-
and trans-configuration [20]. Only nickel bis(di-tert-butyl-
phosphinoenolates) exist exclusively as trans-isomers [21].
The preference for trans-bis(PʝOϪ-chelates) thus increases
in the order Et2P << tBuPhP ഠ cHex2P < iPr2P < tBu2P
and matches the order of Tolman angles of dialkylphe-
nylphosphines (Et2PhP, iPr2PhP, cHex2PhP, tBu2PPh; ␽
136, 155, 162, 170 [18]) except for diisopropyl and dicyclo-
hexyl groups.
Use of nickel bis(phosphinophenolates) for the
polymerization of ethylene
Figure 2 Pressure time plots for batch oligo- or polymerization of
ethylene with: a) [Ni(2-Ph2PC6H4O)2] / 2NiBr2·DME / 3NaH (so-
lid), b) 2a / NiBr2·DME / 4 NaH at 100 °C (dash), c) as b) but at
130 °C (dot). Catalyst each 100 µmol, solvent 20 mL, initial pres-
sure increase by heating from 20 to 100 °C, for further data see
Table 4.
As referred to in the introduction, organonickel 2-phosphi-
nophenolates are efficient catalysts for the poly- or oligo-
merization of ethylene, and nickel bis(2-phosphinophenol-
ates), shown for 2a in case of a small ethylene to catalyst
ratio, are the spent form of the catalysts [12]. The lability
of nickel bis(2-phosphinophenolates), indicated by cis-trans
isomerizations of 2b or 2f on change of the molecular en-
vironment, should allow reactivation to improve the pro-
ductivity of the catalysts or activation to use the air-stable
nickel bis(2-phosphinophenolates) themselves as precata-
lysts. It was shown already that nickel bis(2-diphenylphos-
phinophenolates) can be activated by heating with
NiBr2·DME and excess sodium hydride in toluene in pres-
ence of ethylene (50 bar). The polymerization rate (ethylene
consumption rate), for [Ni(2-Ph2PC6H4O)2] / 2NiBr2·
DME / 3NaH visualized by the pressure-time plot (Fig-
ure 2, plot a), is slow as compared to that with the orga-
nonickel catalyst formed in situ from 2-diphenylphosphino-
phenol and Ni(1,5-COD)2 under the same conditions, but
the selectivity for linear polyethylene is unchanged, and the
total conversion of ethylene is improved [12]. Attempts to
activate nickel bis(dialkylphosphinophenolates) with excess
NiBr2·DME and sodium hydride in toluene as catalyst for
the polymerization of ethylene failed, but we observed for
2a that replacement of toluene by THF, allowing at least
partial solution of the salts, enabled slow formation of an
oligomerization catalyst. The pressure-time plots (Figure 2,
plots b and c) indicate very long induction periods (12 h at
100 °C and 6 h at 130 °C) but the conversions in the sub-
sequent oligomerization come close to those for the catalyst
generated in situ from 1a and Ni(COD)2 (84 %) [12], and
the selectivity for linear α-olefins is comparable (Table 4).
The molecular weights are lower than those of the poly-
ethylene obtained with the catalyst formed from 1a and
Ni(COD)2 in toluene (Mw 21800, Mn ca. 8000 g·molϪ1
[12]), but this is due to the solvent effect of THF. Attempts
to activate the more bulkily substituted 2b in the same way
as 2a or by heating with NaBH4 in THF / ethylene (50 bar)
failed, and little conversion of ethylene to polyethylene was
observed upon heating with 2b and Ni(1,5-COD)2 in THF,
even at 130 °C.
Figure 3 Pressure time plots for batch polymerization of ethylene
with: a) 2a / nBuLi in THF at 100 °C (solid), b) 2b / nBuLi in
THF at 100 °C (dash), c) 2b / nBuLi in toluene at 100 °C (dot), d)
Ph2PC6H4OH / Ph3P / Ni(1,5-COD)2 in toluene at 100 °C (dash-
dot).
To circumvent the disadvantageous low solubility of the
inorganic hydrides and low stability of the catalysts at high
temperature, attempts were made to cleave off one of the
chelate rings of 2a or 2b by polar covalent hydride or alkyl
sources such as triethylsilane or n-butyllithium and to use
the PϳOϪ-ligand for catalyst stabilization, as in diphenyl-
phosphinophenolate-phosphine oligomerization catalysts
[22, 23], instead of trapping it by excess nickel(II). Heating
ethylene in the presence of 2a and triethylsilane in THF
furnished HDPE with high selectivity for linear α-olefins,
but the conversion and reaction rate are low even at high
temperature (130 °C). The catalyst formed from 2b and
Et3SiH in toluene gives similar results (Table 4). Higher
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J. Heinicke, M. Köhler, N. Peulecke, W. Keim, P. G. Jones
productivities are achieved by the use of n-butyllithium.
Solutions formed from n-butyllithium with 2a or 2b in THF
or toluene cause oligo- or polymerization of ethylene at
100 °C. The reactions start within 2 h but are then slower
than after activation of 2a with NiBr2·DME and sodium
hydride. The pressure-time plots (Figure 3, plots a-c) re-
semble that of the oligomerization catalyst obtained from
2-diphenylphosphinophenol, Ni(1,5-COD)2 and triphenyl-
phosphine (Figure 3, plot d) [24] and can be understood in
terms of competing coordination of the liberated phos-
phine, ethylene and THF for the catalyst (eq. 3), which
slows down the rate of the chain growth reaction. In case
of 2a / nBuLi / THF a soft wax consisting of linear α-olefins
was isolated after THF and oligomers were removed by
flash distillation. The short chain lengths suggest that the
rate of the β-olefin elimination is much less decreased by
the auxiliary phosphine and THF than that of the chain
growth. The catalyst 2b / nBuLi / THF produced linear
HDPE (Table 4). The higher molecular weight is due to the
higher basicity of the cHex2P as compared to the Et2P
group, as observed with catalysts formed from 1a or 1b and
Ni(COD)2 [12], and to steric hindrance of the coordination
of the liberated 2-cHex2PC6H4OϪ to the catalyst (cf. [24]).
The low effect of THF, which usually causes a strong de-
crease of the molecular weights, is not clear. As compared
to polyethylene obtained with the catalyst 1b / NiCOD)2
in toluene (Mw 59000, Mn 26500 g/mol) [12], however, the
molecular weights are lower. The lower molecular weights
in the polymerization with 2b / nBuLi in toluene may be due
to stronger interactions with cHex2PC6H4OϪ in absence of
THF, and increase if NiBr2·DME is added to trap this li-
gand (Table 4), but by far not to the value observed with
1b / Ni(COD)2 in toluene. The slow reaction rate (Figure 4,
plot a) shows that this heterogeneous catalyst system is dis-
tinct from the homogenous catalyst formed from 1b and
Ni(COD)2 (Figure 4, plot b) and more similar to the cata-
lyst [Ni(2-Ph2PC6H4O)2] / 2NiBr2·DME / 3NaH (cf. Figure
Table 4 Poly- and oligomerization of ethylene by catalysts derived from 2a or 2b
exp.
catalyst components
(µmol)
solvent, initial
pressure (bar),
T (°C)
conversion of
C2H4(g (%)),
product:
PE: mp. (°C),
d (g·cmϪ3),
α/internal (%);
Me/olefin,
Me/1000C
TON (mol·molϪ1
)
MNMR (g·molϪ1
)
a)
b)
1
2
3
4
5
6
7
8
2a (113),
NiBr2·1.1DME (113),
NaH (500)
THF, 34, 100
THF, 32, 130
THF, 50, 130
5.3 (54),
1580
HDPE,
n.d.
132-134,
0.953,
n.d.
c)
2a (113),
NiBr2·1.1DME (113),
NaH (500)
6.3 (74),
1785
HDPE,
92:8,
1.4, 5.8
128-130,
0.954,
3400
2a (100),
Et3SiH (620)
3.2 (28),
1070
HDPE,
>97:3,
1.5, 3.7
130-132,
0.956,
6000
2b (96),
Et3SiH (950)
toluene, 50, 130
THF, 50, 100
2.2 (20),
820
HDPE,
92:8,
1.8, 1.5
2.7 g oligomer,d)
7.6 g soft wax,
95:5, 1.3
129-132,
0.957,
16000
2a (110),
nBuLi (150)
11.3 (85),
3660
55-86,
n.d.,
430
2b (88),
nBuLi (150)
THF, 50, 100
9.0 (79),
3210
HDPE,
>97:3,
1.2, 2.2
132-133,
0.975,
6600
2b (108),
nBuLi (170)
toluene, 50, 100
toluene, 50, 100
11.1 (81),
3660
HDPE,
95:5,
1.2, 13
115-118,
0.961,
1300
2b (108),
nBuLi (205),
NiBr2·1.1DME (110)
10.0 (73),
HDPE,
>97:3,
1, 2.6
130-131,
0.962,
5300
e)
3240
a)
M
NMR
by 1H NMR integration (for low-molecular weight polymers similar to Mn) [12]. b) Induction period 12 h. c) Induction period 6 h. d) Yield rel. to
C2H4: C4 1.5, C6 4.9, C8 5.7, C10 3.0, C12 0.6 %; isomers < 0.1 % (GC). e) TON rel. to 2b.
1186
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Z. Anorg. Allg. Chem. 2004, 630, 1181Ϫ1190

2-Dialkyl- and 2-tert-Butylphenylphosphinophenol(ate) Nickel and Palladium Complexes
of hydrogen and carbon nuclei use for the phenolate ring numbers
1 to 6 according to the nomenclature (see eq. (1)), for P-alkyl and
cyclohexyl α, β, γ, δ and for P-phenyl groups i, o, m, p. Coupling
constants refer to JHH in 1H and JPC in 13C NMR data unless
1
stated otherwise. τ means a pseudotriplet appearance of H or 13C
signals by coupling with two phosphorus nuclei, N ϭ ΗJϩJЈΗ.
Nickel complexes
cis-Bis[2-(diethylphosphino)phenolato]nickel(II) (2a). The dark green
solution of nickelocene (278 mg, 1.5 mmol) and 1a (536 mg,
2.9 mmol) in toluene (50 mL) was refluxed for 15 h. After partial
evaporation of the solvent and cooling to room temperature the
precipitate was filtered, washed with a small amount of cold hexane
and dried for some hours at 10Ϫ4 Torr to yield 480 mg (76 %) of
2a as yellow powder, mp. > 250 °C, soluble in CDCl3 with orange
color.
Figure 4 Pressure time plots for batch polymerization of ethylene
with: a) 2b / nBuLi / NiBr2·DME in toluene at 100 °C (dash), b)
1b / Ni(1,5-COD)2 in toluene at 100 °C (solid).
C20H28O2P2Ni (421.08); C 57.12 (calc. 57.05); H 6.68 (6.70) %.
3
1H NMR (CDCl3): δ ϭ 1.30 (dt, JPH ϭ 18.1, 3J ϭ 7.5 Hz, 12 H, CH3),
1.70-1.90 (m, 8 H, CH2), 6.54 (t, 3J ഠ 7.2 Hz, 2 H, 4-H), 6.87-6.97 (m, 4 H,
3-H, 6-H), 7.19 (t, 3J ഠ 7.6 Hz, 2 H, 5-H). 13C{1H} NMR (CDCl3): δ ϭ 8.7
(s, CH3), 19.5 (τ, N ϭ 30.0 Hz, 8 H, PCH2), 113.5 (τ, N ϭ 55.8 Hz, C-2),
115.3 (τ, N ϭ 7.0 Hz, C-4), 118.8 (τ, N ϭ 12.9 Hz, C-6), 128.3 (s, C-3), 133.8
(s, C-5), 176.0 (τ, N ϭ 15.6 Hz, C-1). 31P{1H} NMR (C6D6): δ ϭ 39.0.
2, plot a), but, as the selectivity is unchanged, it differs
probably only by slower but longer lasting catalyst genera-
tion and much lower stationary catalyst concentration. The
mechanism assumed for the oligo- or polymerization of eth-
ylene by the nickel(II) phosphinophenolate catalysts
(eq. (3)), apart from the activation of 2, corresponds to that
proposed by Keim for phosphinoenolates [1].
The catalyst systems reported here show principal ways
to activate nickel(II) bis(2-dialkylphosphinophenolates) or
to reactivate the spent-form of these catalyst systems.
Molecular weights of polyethylenes were lower than of
those obtained with related 2-Alk2PC6H4OH / Ni(COD)2
catalysts but, except in experiments 5 and 7 by the presence
of the PϳOLi-ligand, generally higher than with nickel(II)
2-diphenylphosphinophenolate catalysts. Though MAO
seems unsuitable to activate nickel 2-phosphinophenolates,
more efficient hydride or alkyl activators / donors may be
found to improve these systems in future work. Finally, it
should be mentioned that attempts to oligo- or polymerize
ethylene with solutions prepared from the analogous pal-
ladium bis(PʝO-chelate) 5b and nBuLi failed under anal-
ogous conditions, probably due to the higher stability of
organopalladium(II)-2-phosphinophenolates.
trans- and cis-Bis[2-(dicyclohexylphosphino)phenolate]nickel(II) (2b).
Nickelocene (166 mg, 0.9 mmol) and 1b ( 510 mg, 1.8 mmol) in
toluene (50 mL) were refluxed overnight. On cooling to room
temperature green microcrystals of 2b were collected and dried in
vacuum, yield 407 mg (71 %), mp. > 250 °C. The crystals are sol-
uble in C6D6 with light green and in CDCl3 with orange color.
C36H52O2P2Ni (637.45); C 67.81 (calc. 67.83); H 8.11 (8.22) %.
trans-2b in C6D6:
1H NMR: δ ϭ 1.00-1.30 (m, 12 H, Cy), 1.53 (br s, 4 H), 1.68-2.05 (m, 20 H,
Cy), 2.15-2.25 (m, 4 H, α-H), 2.71 (d, 3JPHϭ 11.4 Hz, 4 H, β-H), 6.50 (t,
3J ϭ 7.0-7.4 Hz, 2 H, 4-H), 6.87 (d br, 3J ϭ 8 Hz, 2 H, 6-H), 7.04 (td, 3J ഠ
7.6, 4J ഠ 1.3 Hz, 2 H, 5-H), 7.12 (ddd, 3J ϭ 7.7, 3JPHϭ 4.0, 4J ϭ 1.4-1.6 Hz,
2 H, 3-H). 13C{1H} NMR: δ ϭ 27.1 (s, C-δ), 27.8 (τ, N ഠ 10 Hz, C-γ), 27.9
(τ, N ഠ 13 Hz, C-γЈ), 29.1 (s, C-β), 29.4 (s, C-βЈ), 34.1 (τ, N ϭ 22.3 Hz, C-
α), 114.3 (τ, N ϭ 41.2 Hz, C-2), 115.2 (τ, N ca. 4 Hz, C-4), 120.1 (τ, N ϭ
6.9 Hz, C-6), 132.4 (s, C-3), 133.3 (s, C-5), 180.5 (τ, N ϭ 32 Hz, C-1).
31P{1H} NMR: δ ϭ 27.9.
cis- and trans-2b in CDCl3:
1H NMR (CH-COSY): cis δ ϭ 1.15-1.40 (m, 16 H, βЈ,γ,γЈ,δ-H), 1.40-1.60
(m, 4 H, β-H), 1.65-2.00 (m, 16 H, δ,γ,γЈ,β-H), 2.05-2.20 (br m, 4 H, α-H),
2.80-2.92 (br m, 4 H, βЈ-H), 6.45 (t, 3J ϭ 7.0-7.6 Hz, 2 H, 4-H), 6.89 (d br,
3J ϭ 8.1 Hz, 2 H, 6-H), 6.96-6.98 (m, 2 H, 3-H), 7.1 (t, 3J ϭ 7.6 Hz, 2 H, 5-
H); trans δ ϭ 1.90-2.00 (m, 12 H, β,γ,γЈ-H), 2.20 (br m, 4 H, α-H), 2.54 (d
br, 2J ഠ 12 Hz, βЈ-H), 6.40 (t, 4-H), other signals superimposed. Ϫ 13C NMR
(CH-COSY, DEPT): cis δ ϭ 26.0 (s, C-δ), 27.12-27.25 (m, 2 C, C-γ/γЈ), 28.0
(s, C-β), 30.0 (s, C-βЈ), 35.6 (τ, N ϭ 24.4 Hz, C-α), 113.8 (τ, N ϭ 53.0 Hz,
C-2), 114.4 (τ, N ഠ 6.4 Hz, C-4), 118.7 (τ, N ϭ 11.3 Hz, C-6), 130.3 (s, C-
3), 133.2 (s, C-5), 175.7 (τ, N ϭ 15 Hz, C-1); trans δ ϭ 21.6 (s, C-δ), 26.9-
27.0 (m, 2 C, C-γ/γЈ), 27.9 (s, C-β), 32.9 (τ, N ϭ 21.2 Hz, C-α), 113.9 (s, C-
4), ca. 118.2 (τ, C-6), 131.4 (s, C-3), 132.0 (s, C-5), (C-1 and C-2 uncertain
by low intensity). 31P{1H} NMR: cis δ ϭ 45.5, trans δ ϭ 27.1; at 25 °C cis /
trans ca. 10:1, at Ϫ40 °C only cis-isomer.
Experimental Section
General
All reactions were carried out under argon, using Schlenk tech-
niques and freshly distilled dry solvents. The 2-dialkylphosphino-
phenols and 2-tert-butylphenylphosphinophenol were synthesized
as reported earlier [12], other chemicals were purchased. Ethylene
(99.5 %, Air Liquide) was used without further treatment. Melting
points were performed with a Sanyo Gallenkamp melting point
apparatus, elemental analyses with a CHNS-932 analyzer from
LECO using standard conditions. NMR spectra were recorded on
a multinuclear FT-NMR spectrometer ARX300 (Bruker) at 300.1
(1H), 75.5 (13C), and 121.5 (31P) MHz. Shift references are tetra-
methylsilane for 1H and 13C and H3PO4 (85 %) for 31P. Assignments
Palladium complexes
trans-Bis[2-(diethylphosphino)phenol-η1-P]palladiumdichloride semi-
hydrate(3a·0.5 H2O).
Na2PdCl4 (279 mg, 0.95 mmol), dissolved in methanol (10 mL),
was added to a solution of 1a (380 mg, 2.09 mmol) in methanol
(10 mL) affording a yellow precipitate. To complete the reaction,
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1187

J. Heinicke, M. Köhler, N. Peulecke, W. Keim, P. G. Jones
the mixture was stirred for 1 h at 40 °C. Then the precipitate was
separated, washed with water and dried in vacuum to give 205 mg
(40 %) of 3a·0.5 H2O as yellow powder, sparingly soluble in C6D6,
mp. > 220 °C.
C20H30Cl2O2P2Pd·0.5 H2O (550.74); found C 43.77 (calc. 43.62); H
5.81 (5.67) %.
trans-Bis[2-(diisopropylphosphino)phenol-η1-P]palladiumdichloride (3c).
1c (538 mg, 2.56 mmol), dissolved in methanol (10 mL), was added
to a solution of Na2PdCl4 (342 mg, 1.16 mmol) in methanol
(10 mL). After stirring for 1 h at 40 °C the precipitate was collected,
washed with water and dried in vacuum to give 506 mg (73 %) of
3c as yellow powder, slightly soluble in C6D6.
3
1H NMR (D8-THF): δ ϭ 1.15 (tτ, JHH ϭ 7.7, N ഠ 17.9 Hz, 12 H, CH3),
C24H38Cl2O2P2Pd (597.84); C 48.62 (calc. 48.22); H 6.35 (6.41) %.
3
4
2.17-2.41 (m, 8 H, CH2), 6.74 (ddd, JHH ϭ 8.1 Hz, JHH ϭ 0.6 Hz, JPH
ഠ
IR (nujol): ν¯ ϭ 3311 cmϪ1 s νOH
.
1H NMR (D8-THF): δ ϭ 1.16 (dτ, 3JHH ϭ
3
4
2 Hz, 2 H, 6-H), 6.84 (td, JHH ϭ 7.4, 7.5 Hz, JHH ϭ 0.6 Hz, 2 H, 4-H),
7.23 (dd, JHH ϭ 8.1, 7.4 Hz, JHH ϭ 1.6 Hz, 2 H, 5-H), 7.81 (τdd, N ϭ
11.6, JHH ϭ 7.5, JHH ϭ 1.6 Hz, 2 H, 3-H), 8.80 (s, 2 H, OH); 2.53 (br s,
H2O). 13C{1H} NMR (D8-THF): δ ϭ 9.1 (s, CH3), 16.0 (τ, N ϭ 29.1 Hz,
CH2), 116.3 (s, C-6), 117.0 (τ, N ϭ 43.5 Hz, C-2), 119.9 (τ, N ϭ 10.4 Hz, C-
4), 132.5 (s, C-5), 137.0 (τ, N ϭ 12.6 Hz, C-3), 160.4 (s, C-1). 31P{1H} NMR
(D8-THF): δ ϭ 14.9.
3
7.1, N ϭ 14.2 Hz, 12 H, CH3A), 1.32 (dτ, JHH ϭ 7.1, N ϭ 17 Hz, 12 H,
3
4
CH3B), 2.89-3.00 (m, 4 H, CH), 6.83 (m, 3JHH ϭ 8.1, 4JHH ϭ 1, N ഠ 4.4 Hz,
3
4
2 H, 6-H), 6.89 (t br, 3JHH ഠ 7.5 Hz, 2 H, 4-H), 7.26 (dt br, JHH ϭ 8.1, 7.1,
3
4JHH ϭ 1.4 Hz, 2 H, 5-H), 7.49 (ddτ, JHH ϭ 7.6, JHH ϭ 1.4, N ϭ 9.0 Hz,
2 H, 3-H), 8.41 (s, 2 H, OH). 13C{1H} NMR (D8-THF): δ ϭ 18.6 (s, CH3A),
19.8 (s, CH3B), 23.4 (τ, N ϭ 25 Hz, CH), 113.0 (τ, N ϭ 40.7 Hz, C-2), 118.3
(s, C-6), 120.0 (τ, N ϭ 8.1 Hz, C-4), 132.4 (s, C-5 or C-3), 135.9 (s br, C-3
or C-5), 161.2 (τ, N ϭ 4.4 Hz, C-1). 31P{1H} NMR (D8-THF): δ ϭ 29.4.
3
4
cis-Bis[2-(diethylphosphino)phenolato]palladium(II) (5a).
trans-Bis[2-(diisopropylphosphino)phenolato]palladium(II) (5c).
3a·0.5 H2O, prepared as described above from 1a (210 mg,
1.156 mmol) and Na2PdCl4 (170 mg, 0.578 mmol), was dissolved
in methanol and stirred with Na2CO3 (100 mg, 0.94 mmol) for 1 h
at 40 °C and overnight at 20 °C. NMR-spectra of the crude product
showed broad bands (δ 31P ϭ 51.4). Methanol was evaporated, the
residue was washed with water and hexane, and the complex was
extracted with CHCl3. Evaporation of the solvents afforded 163 mg
(60 %) of yellow 5a, m.p. > 220 °C.
Na2CO3 (500 mg) was added to a solution of 3c (300 mg,
0.50 mmol) in THF (10 mL), and the suspension was stirred for 1 h
at 60 °C. After removal of the main part of the solvent and cooling
to room temperature the precipitate was collected, washed with
water and dried in vacuum to afford 150 mg (57 %) of 5c as yellow
powder, soluble in C6D6 or CDCl3.
C24H36O2P2Pd (524.92); C 55.21 (calc. 54.92); H 7.13 (6.91) %.
3
1H NMR (CDCl3): δ ϭ 1.29 (dτ, JHH ϭ 7.0, N ϭ 15.6 Hz, 12 H, CH3A),
C20H28O2P2Pd (468.81); C 50.95 (calc. 51.24); H 6.12 (6.02) %.
3
3
1.42 (dτ, JHH ϭ 7.0, N ϭ 17.5 Hz, 12 H, CH3B), 2.55 (sept τ, JHH ϭ 7.0,
3
1H NMR (CDCl3): δ ϭ 1.17 (dt, JPH ϭ 18.8, 3J ϭ 7.5 Hz, 12 H, CH3),
3
4
N ϭ 4.7 Hz, 4 H, CH), 6.49 (tdτ, JHH ഠ 7.2 Hz, JHH ϭ 1 Hz, N ഠ 2 Hz,
1.82-2.15 (m, 8 H, CH2), 6.56 (ddbr, 3J ഠ 7.0, 7.5 Hz, 2 H, 4-H), 6.88-6.97
(m, 4 H, 3-H, 6-H), 7.21 (ddbr, 3J ഠ 7.5, 8.2 Hz, 2 H, 5-H). 13C{1H} NMR
(CDCl3): δ ϭ 8.5 (s, CH3), 20.7 (τ, N ϭ 34.0 Hz, 8 H, PCH2), 112.2 (τ, N ϭ
51.6 Hz, C-2), 115.4 (τ, N ϭ 8.0 Hz, C-4), 119.4 (τ, N ϭ 17.1 Hz, C-6), 128.9
(s, C-3), 133.9 (s, C-5), 177.3 (τ, N ϭ 11.6 Hz, C-1). 31P{1H} NMR:
δ(CDCl3) ϭ 48.6, δ(C6D6) ϭ 48.4.
3
4
2 H, 4-H), 6.72 (dm, JHH ϭ 8.9, JHH ϭ 1, N ഠ 4 Hz, 2 H, 6-H), 7.07-7.13
(m, 4 H, 3-H and 5-H). 13C{1H} NMR (CDCl3): δ ϭ 18.0 (s, CH3A), 18.2 (τ,
N ϭ 5.1 Hz, CH3B), 24.6 (τ, N ϭ 24 Hz, CH), 111.6 (τ, N ϭ 38.7 Hz, C-2),
114.7 (τ, N ϭ 6.8 Hz, C-4), 118.9 (τ, N ϭ 10.6 Hz, C-6), 131.6, 132.7 (2 s,
C-3 and C-5), 180.1 (τ, N ϭ 24.7 Hz, C-1). 31P{1H} NMR: δ(CDCl3) ϭ 53.1,
δ(C6D6) ϭ 53.7.
cis- and trans-Bis[2-(dicyclohexylphosphino)phenolato]palladium(II)
(5b).
trans-Bis(2-dicyclohexylphosphino-4,6-di-tert-butylphenolato)pal-
ladium(II) (5d).
a) 1b (621 mg, 2.14 mmol) was added to a solution of Na2PdCl4
(285 mg, 0.97 mmol) in methanol (20 mL) and stirred for 3 h at
40 °C. After cooling the precipitate was filtered, washed with water,
dried in vacuum and sublimed at 160 °C / 2·10Ϫ2 Torr to give
490 mg (74 %) of spectroscopically pure cis-5b as pale-yellow
microcrystals, mp. >220 °C.
A solution of 1d (610 mg, 1.52 mmol) in methanol (10 mL) and
then Na2CO3 (106 mg, 1.0 mmol) was added to Na2PdCl4 (139 mg,
0.47 mmol) dissolved in methanol (10 mL). The mixture was stirred
overnight at 40 °C, cooled to room temperature and filtered. The
yellow precipitate was washed with water and dried in vacuum to
give 320 mg (74 %) of 5d.
C36H52O2P2Pd (685.18); C 60.36 (combustion incomplete, calc.
63.11); H 7.47 (7.65) %.
C52H84O2P2Pd (909.60); C 68.90 (calc. 68.66); H 9.55 (9.31) %.
1H NMR (C6D6): δ ϭ 1.44 (s, 18 H, tBuA), 1.68 (s, 18 H, tBuB), 1.05-2.0 (m,
4
MS (EI 70 eV, 330 °C): m/e ϭ 686 (100 %) [Mϩ], 604 (48 %), 524 (20 %), 522
(25 %), 520 (44 %), 289.5 (23 %), 55 (34 %). 1H NMR (CDCl3): δ ϭ 1.10-
1.35 (m, 16 H, Cy), 1.35-1.53 („q“, 4 H, Cy), 1.60-1.95 (m, 16 H, Cy), 2.17-
36 H, Cy), 2.30-2.56 (m, 8 H, Cy), 7.21 (τd, N ϭ 9.3, JHH ϭ 2.3 Hz, 2 H,
4
3-H), 7.54 (d, JHH ϭ 2.3 Hz, 1 H, 5-H). 13C{1H} NMR (CDCl3): δ ϭ 26.1
(s, δ-CH2), 26.8 (τ, N ϭ 13.4 Hz, γ-CH2), 27.0 (τ, N ϭ 11.5 Hz, γЈ-CH2),
28.5 (s, β-CH2), 29.0 (s, βЈ-CH2), 29.3 (s, CMe3),29.7 (s, βЈ-CH2), 31.8 (s,
CMe3), 33.8 (s, CMe3), 34.2 (τ, N ϭ 24.1 Hz, α-CH), 35.2 (s, CMe3), 111.0
(τ, N ϭ 38.7 Hz, C-2), 125.9 and 126.6 (2s, C-3 and C-5), 135.7 (τ, N ϭ
7.0 Hz, C-4), 137.8 (τ, N ϭ 10.4 Hz, C-6), 176.6 (τ, N ϭ 24.5 Hz, C-1).
31P{1H} NMR: δ(C6D6) ϭ 48.6, δ(CDCl3) ϭ 48.7.
3
4
2.37 (m, 8 H, Cy), 6.51 (td, JHH ഠ 7.2 Hz, JPH ϭ 0.9 Hz, 2 H, 4-H), 6.92
3
4
4
(dd br, JHH ഠ 8.5, JPH ഠ 3 Hz, 2 H, 6-H), 7.02 (τd, N ϭ 16.7, JHH
ϭ
1.5 Hz, 2 H, 3-H), 7.19 (t br, JHH ഠ 7.5 Hz, 2 H, 5-H). 31P{1H} NMR
3
(CDCl3): δ ϭ 59.9.
b) 1b (86 mg, 0.296 mmol) was stirred with Na2PdCl4 (43 mg,
0.146 mmol) in methanol (5 mL) and excess Na2CO3 (32 mg,
0.30 mmol) for 2 h at 40 °C to give a precipitate of trans-5b which
was separated, washed with water and dried in vacuum, yield 80 mg
(79 %), mp. >220 °C. In C6D6 solution trans-5b isomerizes slowly
to cis-5b.
13C{1H} NMR (C6D6): trans: δ ϭ 26.0 (s, δ-CH2), 27.65 (τ, N ϭ 12.4 Hz,
γ,γЈ-CH2), 29.2 (s, β-CH2) , 29.4 (br s, βЈ-CH2), 34.9 (τ, N ϭ 24.0 Hz, α-
CH2), 112.6 (τ, N ϭ 39.2 Hz, C-2), 115.6 (τ, N ϭ 6.6 Hz, C-4), 120.5 (τ, N ϭ
10.6 Hz, C-6), 132.9 (s, C-3), 133.7 (s, C-5), 182.0 (τ, N ϭ 25.4 Hz, C-1); cis:
δ ϭ 26.9 (s, δ-CH2), 27.8 (τ, N ϭ 10.1 Hz, γ,γЈ-CH2), 28.7 (s, β-CH2) , 30.4
(s, βЈ-CH2), 36.7 (mABX, N ϭ 27.4 Hz, α-CH2), 114.1 (mABX, N ϭ 48.9 Hz,
C-2), 115.1 (τ, N ϭ 7.2 Hz, C-4), 120.2 (τ, N ϭ 17.1 Hz, C-6), 131.7 (s, C-
3), 135.0 (s, C-5), 179.4 (τ, N ϭ 9.6 Hz, C-1). 31P{1H} NMR (C6D6) δ ϭ
45.4, 58.8 (trans / cis-intensity after 1 h Ն 95:5, 4d 30:70, 7d 0:100 %).
trans-Bis(2-diisopropylphosphino-4,6-di-tert-butylphenolato)pal-
ladium(II) (5e).
1e (135 mg, 0.419 mmol) was stirred with Na2PdCl4 (63 mg,
0.214 mmol) and excess Na2CO3 (30 mg, 0.283 mmol) in methanol
(5 mL) for 1 h at 40 °C and overnight at 20 °C to give a yellow
precipitate of trans-5e which was separated, washed with water and
dried in vacuum; yield 152 mg (97 %), mp. >220 °C.
C40H68O2P2Pd (749.35); C 64.17 (calc. 64.11); H 9.49 (9.15) %.
1H NMR (C6D6): δ ϭ 1.18 (dτ, 3JHH ϭ 7.8, N ϭ 15.0 Hz, 12 H, CH3A), 1.41
(s, 18 H, tBuA), 1.44 (dτ, 3JHH ϭ 7.3, N ϭ 21 Hz, 12 H, CH3B), 1.65 (s, 18 H,
tBuB), 2.36 (m, 4 H, CH), 7.08 (τd, N ϭ 4.6, 4JHH ϭ 2.3 Hz, 2 H, 3-H), 7.52
4
(d, JHH ϭ 2.3 Hz, 1 H, 5-H). 13C{1H} NMR (C6D6): δ ϭ 19.0 (s, CH3A),
19.9 (τ, N ϭ 6.3 Hz, CH3B), 25.9 (τ, N ϭ 23.9 Hz, CH), 30.5 (s, CMe3), 32.8
1188
 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2004, 630, 1181Ϫ1190

2-Dialkyl- and 2-tert-Butylphenylphosphinophenol(ate) Nickel and Palladium Complexes
(s, CMe3), 34.8 (s, CMe3), 36.4 (s, CMe3), 112.0 (τ, N ϭ 39.7 Hz, C-2), 126.3
Table 5 Crystal data and structure refinement of 4d.
(s, C-5), 128.0 (s, C-3), 137.3 (τ, N ϭ 7.0 Hz, C-4), 139.4 (τ, N ϭ 10.5 Hz,
C-6), 177.7 (τ, N ϭ 24.5 Hz, C-1). 31P{1H} NMR: δ(C6D6 or CDCl3) ϭ 56.2.
Empirical formula
Formula weight
Temperature
C32H36ClO2P2Pd
656.40
trans-[2-(tert-butylphenylphosphino)phenolato-2-(tert-butylphenyl-
phosphino)phenol] palladium(II)chloride (4f) and cis- and trans-
Bis[2-(tert-butylphenylphosphino)phenolato] palladium(II) (5f).
133(2) K
˚
Wavelength
0.71073 A
Crystal system
Space group
Unit cell dimensions
monoclinic
P21/c
a ϭ 10.9610(8) A
˚
A solution of 1f (610 mg, 2.36 mmol) in methanol (10 mL) was
added to Na2PdCl4 (315 mg, 1.07 mmol) dissolved in methanol and
stirred for 1 h. NMR control revealed formation of two pairs of
diastereoisomers of 4f and a minor amount of cis-5f. Heating over-
˚
˚
b ϭ 18.2488(12) A
βϭ 110.062(4)°
c ϭ 15.9307(11) A
3
˚
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
2993.2(4) A
4
1.457 Mg/m3
0.844 mmϪ1
1348
night left one pair of diastereoisomers of 4f [in CDCl3 δ(31P) ϭ
3
33.5 and 56.0 (2JPP ϭ 438.1 Hz); δ(1H)tBu ϭ 1.46 (d, JPH
ϭ
15.9 Hz) and 1.61 (d, 3JPH ϭ 15.0 Hz)] along with increased signals
for 5f. Bis(chelate) formation was completed by addition of
Na2CO3 (106 mg, 1.0 mmol). Work-up as above gave 530 mg
(80 %) 5f as yellow powder, mp. >220 °C.
0.20 x 0.13 x 0.05 mm3
1.76 to 28.28°
Ϫ14 Յ h Յ14, Ϫ24 Յ k Յ 24, Ϫ21 Յ l Յ 21
56564
Reflections collected
Independent reflections
7422 [R(int) ϭ 0.0706]
C32H36O2P2Pd (621.00); C 61.81 (calc. 61.89); H 5.82 (5.84) %.
5f:
Completeness to theta ϭ 28.25° 100.0 %
Absorption correction
Semi-empirical from equivalents
Max. and min. transmission
0.928 and 0.821
3
1H NMR (CDCl3): cis δ ϭ 0.93 (d, JPH ϭ 15.7 Hz, 6 H, CH3), 6.46 („t“br,
Refinement method
Full-matrix least-squares on F2
7422 / 6 / 364
0.944
3
3JHH ഠ 7 Hz, 2 H, 4-H), 6.76 („t“, JHH ഠ 8.0-8.3 Hz, 2 H, 5-H), 6.99 (dd,
3JHH ϭ 8.3, 4JPH ϭ 4.2 Hz, 2 H, 6-H) 7.15-7.25 (m, 2 H, 3-H), 7.40-7.50 (m,
4 H, Ph), 7.51-7.62 (m, 6 H, Ph); trans δ ϭ 1.34 (τ, N ϭ 15.9 Hz, CH3), 6.62
Data / restraints / parameters
Goodness-of-fit on F2
3
3
Final R indices [I>2sigma(I)]
R indices (all data)
Largest diff. peak and hole
R1 ϭ 0.0316, wR2 ϭ 0.0635
R1 ϭ 0.0578, wR2 ϭ 0.0692
0.588 and Ϫ0.430 e. A
(„t“br, JHH ഠ 7.6 Hz, 4-H), 6.89 (d br, JHH ഠ 8 Hz, 6-H), 8.18 (m), other
signals superimposed. 13C{1H} NMR (CDCl3): δ ϭ 27.7 (d, J ϭ 2.2 Hz,
CMe3), 37.5 (mABX, N ϭ 27.8 Hz, CMe3),114.6 (τ, N ഠ 7 Hz, C-4), 115.9
(mABX, N ϭ 50.5 Hz, C-2), 119.3 (τ, N ϭ 17.3 Hz, C-6), 128.6 (τ, N ϭ
9.8 Hz, C-m), 130.0 (mABX, N ϭ 44 Hz, C-i) 131.2, 132.1 (2s, C-3 and C-p),
133.4 (τ, N ϭ 8.9 Hz, C-o), 133.9 (s, C-5 ), 176.7 (τ, N ഠ 12 Hz, C-1).
31P{1H} NMR: δ(CDCl3) ϭ 59.4, 42.8; δ(C6D6) ϭ 59.3, 43.1; in both sol-
vents intensity ratio of cis to trans ca. 94:6 %.
Ϫ3
˚
Polymerization
a) Catalyst preparation: The catalyst components given in Table 4
were dissolved or suspended in the given solvent (total volume
20 mL) and united at 0 °C or, in preparations using nBuLi, at
Ϫ30 °C. In experiment 8, NiBr2·1.1DME was added to the solution
obtained from 2b and nBuLi at Ϫ30 °C after stirring for 15 min
at 20 °C.
4f: The ratio of the originally two pairs of diastereoisomers based
on H NMR integration is roughly 55:45 % (w ϭ weaker signal).
1
3
1H NMR (C6D6): δ ϭ 1.32w, 1.34 (both d, JPH ϭ 15.8 Hz, 18 H, tBuchelate),
1.52w, 1.65 (both d, 3JPH ϭ 14.9 Hz, 18 H, tBuopen), 6.45-6.60 (m, 4 H), 6.85-
7.35 (m), 7.31 (tm, 2 H), 7.91 (tm, 2 H), 8.10-8.20 (m, 4 H), 11.59, 11.65 (2
s, 2 H, OH). 31P{1H} NMR (C6D6): δ ϭ 33.4w, 36.2, 54.6, 55.2w (each d,
2JPP ϭ 441.1 Hz).
b) Polymerization of ethylene. A 75 mL stainless steal autoclave
equipped with gas and catalyst inlet valve, manometer and safety
diaphragm was charged with the catalyst solution or suspension
and ethylene, placed into a preheated bath (100 °C), and heated for
15-20 h. The pressure was registered online (HEJU pressure sensor
1-100 bar, Juchheim, connected to digital multimeter and PC). (The
initial pressure increase in Figures 2-4 is attributed to the increasing
temperature. According to internal calibration in absence of cata-
lyst the temperature rises to 80 °C within 12-14 min. and reaches
100 °C after 25-30 min). After cooling the autoclave to 0-5 °C unre-
acted ethylene was allowed to escape, and the reaction mixture was
transferred to a flask. Polyethylene was separated from the liquid,
was stirred for 1 d with methanol / hydrochloric acid (1:1), washed
with methanol and with CH2Cl2, and the residue was dried in vac-
uum. The solvent and liquid oligomers were distilled off (bath ca.
150 °C, 1.5 Torr) for GC analysis. For further details see in ref. [12].
c) Characterization of poly- and oligomers. 1H NMR spectra of
polyethylene were measured at 100 °C using concentrated solutions
in C6D5Br prepared by swelling for 1 d at 120 °C under argon,
acquisition time 4.9-5.4 s, delay 1.0 s. Oligomers were analyzed by
GC (HP 57890) using a HP-5 capillary column (30m x 0.32mm x
0.25µm; 5 % phenyl methyl silicone), nitrogen as carrier gas, two
isothermal runs at 35 and 100 °C, detection by FID and identifi-
cation by selected reference samples and the Kovats-Index.
Single crystals of 4f were grown from an ethereal solution of the
crude product of a separate experiment by slow mixing (overlayer-
ing) with hexane; for crystal structure analysis see below.
Crystal Structure Analysis.
Data collection: A crystal of 4d was mounted on a glass fiber in
inert oil and transferred to the cold gas stream of the diffractometer
(Bruker SMART 1000 CCD). Data were collected with monochro-
mated Mo-Kα radiation and corrected for absorption (program
SADABS)
Structure refinement: The structure was refined anisotropically on
F2 using the program SHELXL-97 [25]. Hydrogen atoms were re-
fined either freely (OH), as rigid methyls, or using a riding model.
The butyl carbons C52-54 are disordered over two positions in the
ratio 9:1.
The crystallographic data are listed in Table 5. For selected bond
lengths and angles of 4f see Tables 1 and 2. Crystallographic data
for 4f have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no. CCDC-228472.
Copies of the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, Uk [Fax: (int.
code) ϩ44-(1223)/336-033, e-mail: deposit@ccdc.cam.ac.uk].
Acknowledgments. We acknowledge the Deutsche Forschungsge-
meinschaft and the Fonds der Chemischen Industrie for the support
Z. Anorg. Allg. Chem. 2004, 630, 1181Ϫ1190
zaac.wiley-vch.de
 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
1189

J. Heinicke, M. Köhler, N. Peulecke, W. Keim, P. G. Jones
of this study. Furthermore we thank M. K. Kindermann, B. Witt
and S. Siegert for numerous NMR measurements and P. Lobitz for
GC analyses.
[11] J. Heinicke, M. He, A. Dal, H.-F. Klein, O. Hetche, W. Keim,
U. Flörke, H.-J. Haupt, Eur. J. Inorg. Chem. 2000, 431Ϫ440;
A. Dal, M. He, J. Heinicke, W. Keim, H.-F. Klein, M. Köhler,
M. Koesling, Phosphorus, Sulfur Silicon 1999, 144Ϫ146,
145Ϫ148.
[12] J. Heinicke, M. Köhler, N. Peulecke, M. He, M. K. Kinder-
mann, W. Keim, G. Fink, Chem. Eur. J. 2003, 9, 6093Ϫ6107;
M. O. Kristen, J. Heinicke, W. Keim, M. Köhler, M. He, DE
199 55 45 (09.11.1999).
[13] T. B. Rauchfuss, Inorg. Chem. 1977, 16, 2966Ϫ2968.
[14] X. Couillens, M. Gressier, Y. Coulais, M. Dartiguenave, Inorg.
Chim. Acta 2003, 357, 195Ϫ201.
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1190
 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
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Z. Anorg. Allg. Chem. 2004, 630, 1181Ϫ1190