Iron and cobalt complexes of a series of tridentate P,N,P ligands - Synthesis, characterization, and application in ethene polymerization reactions

Article abstract of DOI:10.1002/1521-3749(200213)628:13<2839::AID-ZAAC2839>3.0.CO;2-9

A series of tridentate P,N,P ligands comprising a central pyridine unit and two pendent diarylphosphane moieties (2,6-bis(CH₂PAr₂)pyridine; Ar = phenyl (1), 2-methylphenyl (2), 2,4,6-trimethylphenyl (3)) as well as the corresponding iron (1-FeCl2, 2-FeCl2, 3-FeCl2) and cobalt (1-CoCl₂, 2-CoCl₂, 3-CoCl₂) complexes were synthesized and characterized. An X-ray structure analysis of 2-CoCl₂ and 3-CoCl₂ exhibited a trigonal-bipyramidal coordination geometry at the metal center, the two chlorine atoms and the nitrogen occupying the equatorial and the phosphane units the apical positions. IR analysis indicated, that in all complexes the pyridine unit is coordinated to the metal center. The cobalt compounds were applied as catalyst precursors for the polymerization of ethene after activation with MAO.

Full text of DOI:10.1002/1521-3749(200213)628:13<2839::AID-ZAAC2839>3.0.CO;2-9

Iron and Cobalt Complexes of a Series of Tridentate P,N,P Ligands ؊
Synthesis, Characterization, and Application in Ethene Polymerization
Reactions
a,
Gabi Müllera, Martti Klingab, Markku Leskeläb, and Bernhard Rieger *
a Ulm, Department of Materials and Catalysis, Inorganic Chemistry II of the University
b Helsinki/Finland, Laboratory of Inorganic Chemistry, Department of Chemistry of the University
Received May 15th, 2002.
Abstract. A series of tridentate P,N,P ligands comprising a central
pyridine unit and two pendent diarylphosphane moieties (2,6-
bis(CH2PAr2)pyridine; Ar ϭ phenyl (1), 2-methylphenyl (2), 2,4,6-
trimethylphenyl (3)) as well as the corresponding iron (1-FeCl2,
2-FeCl2, 3-FeCl2) and cobalt (1-CoCl2, 2-CoCl2, 3-CoCl2) com-
plexes were synthesized and characterized. An X-ray structure
analysis of 2-CoCl2 and 3-CoCl2 exhibited a trigonal-bipyramidal
coordination geometry at the metal center, the two chlorine atoms
and the nitrogen occupying the equatorial and the phosphane units
the apical positions. IR analysis indicated, that in all complexes
the pyridine unit is coordinated to the metal center. The cobalt
compounds were applied as catalyst precursors for the polymeri-
zation of ethene after activation with MAO.
Keywords: P,N,P ligands; Iron; Cobalt; Ethene polymerization
Eisen- und Cobaltkomplexe mit dreizähnigen P,N,P-Liganden ؊ Synthese,
Charakterisierung und Verwendung als Katalysatoren für die Ethenpolymerisation
Inhaltsübersicht. Eine Reihe von dreizähnigen P,N,P-Liganden, be-
stehend aus einer 2,6-diarylphosphansubstituierten Pyridineinheit
(2,6-bis(CH2PAr2)pyridin; Ar ϭ phenyl (1), 2-methylphenyl (2),
2,4,6-trimethylphenyl (3)), wurde zu den entsprechenden Eisen-
(1-FeCl2, 2-FeCl2, 3-FeCl2) und Cobaltkomplexen (1-CoCl2,
2-CoCl2, 3-CoCl2) umgesetzt. Strukturanalysen an 2-CoCl2 und
3-CoCl2 zeigten in beiden Fällen eine trigonal-bipyramidale Koor-
dinationsanordnung am Cobalt(II). Die Cobalt-Verbindungen
wurden nach Aktivierung mit MAO als Katalysatoren für die Poly-
merisation von Ethen eingesetzt.
Introduction
Iron and cobalt complexes with tridentate 2,6-bis(imino)-
pyridyl ligands (N,N,N ligands) are among the most active
catalyst systems for the polymerization of ethene, contain-
ing metals of group 8 and 9 (Figure 1) [1, 2]. The polymeri-
zation properties of such systems, carrying a variety of dif-
ferent aryl- and backbone substituents, were described in a
number of publications [3Ϫ8]. It was demonstrated, that
the catalyst performance can be controlled by modifying
the aryl substitution pattern, leading to highly active oligo-
merization or polymerization catalysts affording linear,
high molecular weight polyethylenes.
Fig. 1 N,N,N ligands and P,N,P ligands 1 (R ϭ H), 2 (R ϭ
2-CH3) and 3 (R ϭ 2,4,6- CH3).
We report here an approach towards new catalysts which
carry phosphane functionalities instead of the imine groups
of the N,N,N systems (Figure 1). A series of these P,N,P
ligands with differently substituted aryl moieties on the
phosphane units were synthesized; 1 (R ϭ H), 2 (R ϭ
2-CH3) and 3 (R ϭ 2,4,6- CH3).
* Prof. Dr. B. Rieger
Department of Materials and Catalysis
University of Ulm
Results and Discussion
Ligand synthesis and characterization
Albert-Einstein-Allee 11
D-89069 Ulm, Germany
Fax: ϩ49 (0)7 31 50 2 30 39
e-mail: bernhard.rieger@chemie.uni-ulm.de
Treatment of diarylphosphanes with 2,6-bis(chloromethyl)-
pyridine in the presence of a base (potassium tert.-buta-
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846  2002 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 0044Ϫ2313/02/628/2839Ϫ2846 $ 20.00ϩ.50/0
2839

G. Müller, M. Klinga, M. Leskelä, B. Rieger
Fig. 2 Synthesis of the ligands 1, 2, 3 as well as the corresponding iron (1-FeCl2, 2-FeCl2, 3-FeCl2) and cobalt (1-CoCl2, 2-CoCl2, 3-
CoCl2) complexes.
The structure of 2 was determined by single crystal X-ray
analysis. Suitable crystals were obtained from CHCl3/ace-
tone. An Ortep plot of 2 is depicted in Figure 3 (crystal
data, intensity collection and structure refinement param-
eters see Table 3).
Bond lengths and angles are within the limits expected
for these types of bonds (Table 1) [10]. The ligand shows
C2-symmetry in the solid state. The symmetry axis is deter-
mined by the nitrogen and C4 (symmetry equivalent atoms
are labeled with the suffix a).
Fig. 3 Molecular structure of 2. Hydrogen atoms were omitted for
clarity. Thermal ellipsoids are depicted at a 50 % probability level.
Complex synthesis and characterization
Iron (1-FeCl2, 2-FeCl2, 3-FeCl2) and cobalt (1-CoCl2, 2-
nolate) afforded the tridentate P,N,P ligands with variable
sterical demand at the phosphane units (Figure 2) [9]1).
The ligands were characterized by 31P- and 1H NMR
spectroscopy, mass spectroscopy, and elemental analysis.
CoCl2, 3-CoCl2) complexes were synthesized by reacting the
ligands with a solution of iron or cobalt chloride in ethanol
(Figure 2). The iron compounds were isolated as yellow,
amorphous solids, whereas the cobalt analogues were ob-
2)
tained as bright colored (blue 1-CoCl2, violet 2-CoCl2
,
˚
Table 1 Selected bond lengths/A and angles/° for 2.
P1ϪC12
P1ϪC5
P1ϪC1
N1ϪC2
C1ϪC2
C2ϪC3
C3ϪC4
1.836(2)
1.848(2)
1.867(2)
1.346(2)
1.504(3)
1.392(3)
1.383(3)
C12ϪP1ϪC5
C12ϪP1ϪC1
C5ϪP1ϪC1
C2aϪN1ϪC2
N1ϪC2ϪC1
C3ϪC2ϪC1
101.84(9)
101.48(10)
97.58(9)
117.7(2)
116.37(18)
120.85(19)
2) A turquoise form of 2-CoCl2 was isolated by crystallization from
CH2Cl2/PE. In some cases both forms were obtained simulta-
neously. By heating the violet form above 225 °C a color change
from violet to turquoise was observed which is not reversible upon
cooling. No included solvent molecules were found which could
explain this observation. A similar behavior was not observed for
1-CoCl2 or 3-CoCl2. For pentacoordinated cobalt complexes two
isomeric forms, a trigonal-bipyramidal and a square-pyramidal
form exist which are close in energy. The existence of the turquoise
isomer might be attributed to the formation of a square-pyrami-
dal isomer.
’a’ denotes a symmetry equivalent atom at x, Ϫyϩ1, Ϫzϩ1.
1) for 1 see [9]
2840
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846

Iron and Cobalt Complexes of a Series of Tridentate P,N,P Ligands
˚
measurements on the cobalt complexes revealed magnetic
moments between 4.3 and 4.5 µB which is characteristic for
cobalt(II) complexes with three unpaired electrons [17, 11].
The structure of 2-CoCl2 and 3-CoCl2 was determined by
X-ray analysis. Suitable crystals were obtained from chloro-
form (2-CoCl2) and by slow diffusion of hexane into a solu-
tion of 3-CoCl2 in CH2Cl2. An Ortep plot of the structures
is depicted in Figure 4 and 5 (crystal data, intensity collec-
tion and structure refinement parameters see Table 3).
For 2-CoCl2 and 3-CoCl2 a distorted, trigonal-bipyrami-
dal coordination geometry was found. The phosphorus
atoms are located at the apical positions and the chlorine
atoms, together with the nitrogen unit, occupy the equa-
torial coordination sites. Complex 3-CoCl2 shows C2-sym-
metry in the solid state. The symmetry axis is determined
by N1 and Co1 (symmetry equivalent atoms are labeled
with the suffix a).
Table 2 Selected bond lengths/A and angles/° of 2-CoCl2 and
3-CoCl2.
2-CoCl2
Co1ϪN1
Co1ϪCl1
Co1ϪCl2
Co1ϪP1
Co1ϪP2
P1ϪC1
2.097(5)
2.247(2)
2.2794(19)
2.550(2)
2.542(2)
1.809(7)
1.824(7)
1.842(6)
1.819(7)
1.826(6)
1.844(6)
1.499(9)
1.495(9)
1.347(8)
N1ϪCo1ϪCl1
N1ϪCo1ϪCl2
Cl1ϪCo1ϪCl2
N1ϪCo1ϪP2
N1ϪCo1ϪP1
Cl1ϪCo1ϪP1
Cl2ϪCo1ϪP1
P2ϪCo1ϪP1
C1ϪP1ϪCo1
C8ϪP1ϪCo1
C35ϪP1ϪCo1
C22ϪP2ϪCo1
C15ϪP2ϪCo1
C29ϪP2ϪCo1
130.38(16)
111.92(15)
117.68(8)
77.15(15)
78.67(15)
92.09(7)
102.11(7)
155.35(6)
122.0(2)
123.5(2)
88.4(2)
P1ϪC8
P1ϪC35
P2ϪC22
P2ϪC15
P2ϪC29
C29ϪC30
C34ϪC35
N1ϪC34
122.8(2)
121.9(2)
89.2(2)
3-CoCl2
Co1ϪN1
Co1ϪCl1
Co1ϪP1
P1ϪC1
P1ϪC10
P1ϪC19
N1ϪC20
C19ϪC20
C20ϪC21
C21ϪC22
2.057(6)
2.2508(13)
2.6200(13)
1.838(5)
1.846(5)
1.864(5)
1.344(5)
1.505(7)
1.377(7)
1.369(7)
N1ϪCo1ϪCl1
Cl1ϪCo1ϪCl1a
N1ϪCo1ϪP1
Cl1ϪCo1ϪP1a
Cl1ϪCo1ϪP1
P1aϪCo1ϪP1
C1ϪP1ϪCo1
C10ϪP1ϪCo1
C19ϪP1ϪCo1
120.59(4)
118.83(8)
78.48(4)
For 2-CoCl2 a chloroform molecule per one complex unit
was located in the unit cell. The nitrogen-cobalt bond
87.24(4)
104.56(4)
156.96(7)
111.93(15)
133.91(16)
85.11(16)
˚
˚
lengths, 2.097(5) A in 2-CoCl2 and 2.057(6) A in 3-CoCl2,
are comparable with distances found in complexes of simi-
˚
lar types (2.05Ϫ2.16 A) (Table 2) [3, 12, 13, 14]. Extended
˚
P-Co bond lengths 2.542(2) and 2.550(2) A in 2-CoCl2, and
˚
˚
2.6200(13) A in 3-CoCl2 were observed (common P-Co dis-
’a’ denotes a symmetry equivalent atom at Ϫx, y, Ϫzϩ1/2.
tance: 2.25 A) [15]. These distances are longer than values
found in other transition metal complexes comprising li-
˚
green 3-CoCl2), crystalline materials. All compounds were
gand 1 (2.26Ϫ2.37 A) [12, 13, 14, 16]. The extended bond
characterized by elemental analysis and FAB-MS. Magnetic
lengths are most evidently attributed to the ortho-substitu-
Table 3 Crystallographic data for 2, 2-CoCl2 and 3-CoCl2.
2
2-CoCl2•CHCl3
3-CoCl2
molecular formula
formula weight/(g/mol)
crystal color and form
radiation
C35H35NP2
531.58
colorless prisms
Cu-KͰ
orthorhombic
P 2 21 21
8.991(1)
C36H36Cl5CoNP2
780.78
violet prisms
Mo-KͰ
monoclinic
P 21/c
13.307(3)
17.137(5)
15.874(6)
93.43(3)
3613.5(19)
4
1.435
0.960
1604
C43H51Cl2CoNP2
773.62
green prisms
Mo-KͰ
monoclinic
C 2/c
27.713(3)
8.854(4)
20.199(3)
126.85 (1)
3966.0(19)
4
1.296
0.679
crystal system
space group
˚
a/A
˚
b/A
11.353(1)
14.332(1)
˚
c/A
β /°
3
˚
volume/A
1462.9(2)
2
1.207
1.518
564
Z
Dcalcd./Mg/m3
absorption coefficient/mmϪ1
F(000)
1628
crystal size/mm
θmax/°
number of observed reflections [I>2σ(I)]
number of collected reflections
number of unique reflections
number of parameters
index range
0.35 ϫ 0.33 ϫ 0.27
66.99
1997
2190
2025
0.30 ϫ 0.26 ϫ 0.25
25.25
3842
6756
6463
0.30 ϫ 0.25 ϫ 0.20
25.25
2390
3814
3549
173
406
223
0 Յ h Յ 10
Ϫ13 Յ k Յ 5
Ϫ17 Յl Յ 17
1.194
R1 ϭ 0.0384
wR2 ϭ 0.1028
R1 ϭ 0.0387
wR2 ϭ 0.1031
0.342 and Ϫ0.334
0 Յ h Յ 15
0 Յ k Յ 20
Ϫ19 Յ l Յ 19
1.051
R1 ϭ 0.0811
wR2 ϭ 0.1740
R1 ϭ 0.1539
wR2 ϭ 0.1958
0.977 and Ϫ0.947
Ϫ12 Յ h Յ 33
Ϫ7 Յ k Յ 10
Ϫ24 Յ l Յ 19
1.005
R1 ϭ 0.0698
wR2 ϭ 0.1609
R1 ϭ 0.1186
wR2 ϭ 0.1763
0.643 and Ϫ0.510
goodness-of-fit on F2
final R indices [I>2σ(I)]a,b)
R indices (all data)a,b)
3
˚
largest differential peak and hole/(e/A )
a) R1 ϭ ΣʈFoΗϪΗFcʈ/ΣΗFoΗ.
b) wR2 ϭ [Σ[w(Fo2ϪFc2)2]/Σ[wFo4]]1/2
.
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846
2841

G. Müller, M. Klinga, M. Leskelä, B. Rieger
Fig. 4 Molecular structure of 2-CoCl2 (left) and 3-CoCl2 (right). Hydrogen atoms were omitted for clarity. Thermal ellipsoids are depicted
at a 50 % probability level.
Fig. 5 Molecular structure of 2-CoCl2 (left) and 3-CoCl2 (right), side view. Hydrogen atoms were omitted for clarity. Thermal ellipsoids
are depicted at a 50 % probability level.
ent(s) in 2(3) which inhibit a further approach of the phos-
phane units due to steric interaction with the chlorine
atoms.
1566 cmϪ1 in the case of 1) as well as different bands of
substituted aryl units, which in number and position de-
pend on the substitution pattern, can be observed [17, 20].
In the case of 2,6-disubstituted pyridine derivatives a shift
in frequency of about 10Ϫ20 cmϪ1 of the highest ring de-
formation band was observed upon coordination of the li-
gand to a metal center [17, 19].
Structural analysis on iron and cobalt complexes of the
N,N,N ligands revealed an almost planar arrangement of
the bis(imino)pyridyl fragment and the related chelate rings
[1, 2, 3, 7]. In contrast to this our P,N,P ligands form two
non planar 5-membered chelate rings with torsion twists of
33.7(7)° (N1-C30-C29-P2) and 48.5(7)° (N1-C34-C35-P1)
in 2-CoCl2 and 47.4(5)° (N1-C20-C19-P1) in 3-CoCl2 (Fig-
ure 5).
An IR analysis was conducted on the free ligands and on
the corresponding iron and cobalt complexes. Upon coordi-
nation of a pyridine unit a distinct variation of the pyridine
ring deformation can be observed [17, 18, 19]. In Figure 6
the high frequency region (1650Ϫ1350 cmϪ1) of the ring
deformation vibrations of the free ligands as well as of the
corresponding iron and cobalt complexes are depicted. Of
most interest is the region between 1610Ϫ1550 cmϪ1, where
two bands of the 2,6-substituted pyridine (1588 and
The IR-diagrams 1-3 show the spectra of the free ligands
(upper), the cobalt (middle) and the iron (lower) complexes
of 1 (diagram 1), 2 (diagram 2) and 3 (diagram 3). The
spectra of the iron and cobalt complexes of 1 show a high
frequency band at 1597/1598 cmϪ1 which is not present in
the spectrum of the free ligand. This new band can be as-
signed to the coordinated pyridine unit. The band at
1584/5 cmϪ1 observed for the complexes can be attributed
to the phosphane unit and not to uncoordinated pyridine 3)
.
3) Ph3P also shows a band at 1582 cmϪ1
2842
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846

Iron and Cobalt Complexes of a Series of Tridentate P,N,P Ligands
nated to the metal center, as was found also in the structural
analysis of 2-CoCl2 and 3-CoCl2.
Polymerization reactions
The iron and cobalt complexes were testes for the polymer-
ization of ethene after activation with MAO. In the case of
the cobalt species the formation of a yellow solution indi-
cated a reaction between the complexes and MAO. In the
case of the iron complexes a fast decomposition (formation
of a black precipitate) was observed which could be sup-
pressed by the addition of olefins (ethene, n-pentene, nor-
bornene) prior to activation. However the complexes de-
composed rapidly at polymerization temperature, so that no
polymer products could be obtained.
Table 4 Ethene polymerization experiments with the complexes
1-CoCl2, 2-CoCl2, 3-CoCl2 as well as analytical data for the isola-
ted polymers.
run catalyst
Co:MAO temp.
productivity
/(g/molMh)
Mw/(g / mol) Tm
/°C
(PD)
/°C
130
136
135
135
133
131
1
2
3
4
5
6
1-CoCl2
2-CoCl2
3-CoCl2
3-CoCl2
3-CoCl2
3-CoCl2
1:400
60
60
60
60
60
80
74
333 000
(2.0)
1:400
74
331 000
(2.1)
1:400
88
336 000
(2.2)
1:1000
1:1500
1:1000
174
130
225
320 000
(2.1)
302 000
(2.0)
255 000
(2.2)
polymerization conditions: catalyst: 0.1 mmol (run 1Ϫ3), 0.05 mmol (run
4Ϫ6); pressure: 60 bar; solvent: toluene 20 ml (run 1Ϫ3), 10 ml (run 4, 6),
5 ml (run 5);
The cobalt complexes produce polyethylene at elevated
polymerization temperatures (>60 °C, 60 bar) (Table 4).
The activity, molecular weights, polydispersities as well as
the melting points of the isolated polymers are nearly inde-
pendent of the aryl substitution pattern of the ligands (run
1Ϫ3). Higher activities and polymers with lower molecular
weights are obtained at 80°. The productivity depends on
the Co:MAO ratio and shows a maximum at about 1:1000.
However, the activities of the P,N,P cobalt complexes is
about 103 times lower compared to the N,N,N systems
[1, 2].
Fig. 6 IR spectra of the ligands 1, 2 and 3 as well as of the cor-
responding iron (1-FeCl2, 2-FeCl2, 3-FeCl2) and cobalt complexes
(1-CoCl2, 2-CoCl2, 3-CoCl2).
In all cases polymers with high molecular weights (about
300 000 g/mol) and low polydispersities (2.2) were obtained.
Melting points are between 130 and 136 °C and nearly inde-
pendent of the polymerization conditions. Such high melt-
ing points indicate a linear structure of the polyethylene
[1, 3].
Also for the complexes 2-CoCl2 and 2-FeCl2 a high fre-
quency band at 1602/1604 cmϪ1 is present which is not ob-
served in the free ligand. The IR spectrum of 3 shows a
band at 1602 cmϪ1 which results from the 2,4,6-CH3 substi-
tuted aryl moieties [20]. Upon coordination the high fre-
quency band of the coordinated pyridine probably superim-
poses with this band which causes the increase in intensity
at 1600/1601 cmϪ1. No differences between the spectra of
the iron and cobalt complexes were observed. These results
indicate, that in all the cases the pyridine units are coordi-
Conclusion
The P,N,P ligands 1, 2 and 3, carrying different aryl sub-
stituents on the phosphane units, form trigonal-bipyramidal
cobalt complexes which could be characterized by an X-ray
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846
2843

G. Müller, M. Klinga, M. Leskelä, B. Rieger
Bis(2-methylphenyl)halophosphane: 31P NMR (CDCl3): 74.42 (Cl),
66.55 (Br), (Cl:Br ϭ 1:0.9); H NMR (CDCl3): 2.48 (s, 6H, CH3-),
7.17Ϫ7.24 (m, 4H, Ar), 7.31 (m, 2H, Ar), 7.44 (m, 1H, Ar (Br)),
7.49 (m, 1H, Ar (Cl)); MS (EI): m/z 292 (Mϩ, 100 %, 79Br), 294
(Mϩ, 100 %, 81Br).
structure analysis on the complexes 2-CoCl2 and 3-CoCl2.
Polymerization experiments showed, that these complexes
are up to 103 times less active than the N,N,N catalysts.
However, high molecular weight polymers were produced
at elevated temperatures. The low activity could be due to
changes in the overall structure of the ligand which might
cause a drastic decrease in activity and stability as was also
observed in other tridentate ligand systems derived from
the parent N,N,N ligands [21, 22, 23, 24].
1
Bis(2,4,6-trimethylphenyl)halophosphane: 31P NMR (CDCl3):
75.49 (Br), 85.83 (Cl), (Cl:Br ϭ 1:0.5); 1H NMR (CDCl3): 2.26
(s, 6H, CH3-), 2.34 (s, 12H, CH3-), 6.80 (s, 4H, Ar); MS (EI): m/z
304 (Mϩ, 40 %, Cl35), 348 (Mϩ, 60 % , Br79), 350 (Mϩ, 60 % , Br81).
Bis(2-methylphenyl)phosphane, bis(2,4,6-trimethylphenyl)phosphane:
The appropriate amount of the halophosphane (0.1 mol), dissolved
in 200 ml of diethyl ether, was slowly added to a suspension of
LiAlH4 (0.1 mol) in 250 ml of diethyl ether cooled to Ϫ40 °C. The
reaction mixture was allowed to reach RT and was stirred for
further 30 minutes. The excess of LiAlH4 was hydrolyzed by the
careful addition of water at 0 °C. The clear solution was separated
and the residue was extracted with 2 ϫ 200 ml of diethyl ether.
After removal of the solvent under reduced pressure the phosphane
was purified by crystallization from 2-propanol. Yield: 90Ϫ95 %.
Bis(2-methylphenyl)phosphane: 31P NMR (CDCl3): Ϫ57.52;
1H NMR (CDCl3): 2.40 (s, 6H, CH3-), 5.10 (d, 1H, J ϭ 207.0 Hz,
P-H), 7.09 (dd, 2H, Ar), 7.18-7.24 (m, 6H, Ar); MS (CI): m/z 215
(MHϩ, 44 %).
Experimental Part
All manipulations were carried out in dry solvents under an inert
atmosphere of argon using standard Schlenk techniques. THF, di-
ethyl ether and toluene were distilled from LiAlH4, CH2Cl2 and
petroleum ether were distilled from CaH2. Anhydrous acetone and
ethanol were purchased from Merck. All solvents were stored over -
molecular sieves. Commercially available phosphorus trichloride,
diphenylphosphane, 2-bromo-toluene, mesitylbromide, LiAlH4,
2,6-bis(chloromethyl)pyridine, potassium tert.-butanolate, anhy-
drous FeCl2 and anhydrous CoCl2 (Aldrich) were used without
further purification. Polymerization experiments were performed in
an 100 ml steel autoclave (Roth) with a glass inlet and mechanical
stirring. Ethene (BASF, 2.7) was used without further purification.
MAO (10 % in toluene) was purchased from Witko. NMR meas-
urements were conducted on a Bruker DRX 400 spectrometer.
Chemical shifts are reported in ppm. Tetramethylsilane and 85 %
phosphoric acid were used as references. IR spectra were measured
on a Bruker IFS 113v spectrometer, FAB-MS spectra on a Finni-
gan MAT TSQ 7000 spectrometer using a mixture of dimethyl-
formamide (DMF) and 2,3,4-trimethoxyacetophenone (TMAP) as
matrix. EI spectra (temperature range of 30Ϫ300 °C, heating rate
of 25 °C/min) and CI spectra (methane as reactant gas) were per-
formed on a Finnigan MAT SSQ 7000 spectrometer. Elemental
analyses were measured on an Vario EL elementar. Magnetic meas-
urements were conducted on a SQUID magnetometer (Quantum-
Design) at a field strength of 1000 Oe within a temperature range
of 5 to 400 K. Diamagnetic susceptibilities were calculated using
literature data [25]. High temperature GPC measurements were
performed on an Waters alliance 2000 in 1,2,4-trichlorobenzene at
145 °C. DSC was measured on a Perkin Elmer DSC 7 calorimeter
with a heating-/cooling rate of 10°C/min.
Bis(2,4,6-trimethylphenyl)phosphane: 31P NMR (CDCl3): Ϫ92.33;
1H NMR (CDCl3): 2.22 (s, 6H, CH3-), 2.24 (s, 12H, CH3-), 5.22 (d,
1H, J ϭ 235 Hz, P-H), 6.80 (s, 4H); MS (EI): m/z270 (Mϩ, 100 %).
Ligands 1, 2, 3: Potassium tert.-butanolate (60 mmol) was added to
a solution of the appropriate phosphane (30 mmol) in 150 ml of
THF. The reaction mixture was cooled to 0 °C and 2,6-bis(chloro-
methyl)pyridine (15 mmol) was added. The reaction mixture was
stirred at RT for 24 hours. The solvent was removed under reduced
pressure and the remaining solid was dissolved in CH2Cl2 and
water (200 ml each). The organic layer was separated and the water
layer further extracted with 100 ml of CH2Cl2. The organic phase
was dried over Na2SO4 and the solvent was removed under reduced
pressure. The crude product was purified by crystallization from
CHCl3/acetone. Yield 70Ϫ80 %.
1: 31P NMR (CDCl3): Ϫ9.67; 1H NMR (CDCl3): 3.62 (s, 4H, -
CH2-), 6.74 (d, 2H, J ϭ 7.8 Hz, Ar), 7.23 (t, 1H, J ϭ 7.7 Hz, Ar),
7.32 (m, 12H, Ar), 7.45 (m, 8H, Ar); MS (EI): m/z 475 (Mϩ, 55 %);
mp: 149 °C; elemental analysis (C31H27NP2): cal.: C: 78.30, H: 5.72,
N: 2.95, found: C: 78.03, H: 5.73, N: 2.95 %.
2: 31P NMR (CDCl3): Ϫ30.40; H NMR (CDCl3): 2.20 (s, 12H,
1
Bis(2-methylphenyl)halophosphane, Bis(2,4,6-trimethylphenyl)halo-
phosphane: A solution of the appropriate arylbromine (0.25 mol) in
180 ml of THF was added to a suspension of magnesium turnings
(0.30 mol) in 50 ml of THF at such a rate as to keep the reaction
mixture under reflux. After the addition was completed, the reac-
tion mixture was heated under reflux for an additional hour. The
solution was filtered through glass wool and transferred into a
dropping funnel. The Grignard solution was added slowly to a
solution of PCl3 (0.125 mol) in 250 ml of THF, cooled to Ϫ70 °C.
The reaction mixture was allowed to reach RT over night. The
solvent was removed under reduced pressure and the solid residue
was extracted with 3 ϫ 300 ml of petroleum ether. The solvent was
removed under reduced pressure to leave a viscous oil which solidi-
fied slowly. The product was purified by distillation under reduced
pressure. The halophosphanes were obtained as a mixture of the
diarylchloro and diarylbromophosphane. Yield: 85Ϫ90 %.
CH3-), 3.49 (s, 4H, -CH2-), 6.62 (d, 2H, J ϭ 7.5Hz, Ar), 7.08 (m,
4H, Ar), 7.12-7.21 (m, 9H, Ar), 7.35 (m, 4H, Ar); MS (EI): m/z
531 (Mϩ, 25 %); mp: 167 °C; elemental analysis (C35H35NP2): cal.:
C: 79.08, H: 6.64, N: 2.63, found: C: 78.97, H: 6.54, N: 2.64 %.
1
3: 31P NMR (CDCl3): Ϫ18.87; H NMR (CDCl3): 2.13 (s, 24H,
CH3-), 2.19 (s, 12H, CH3-), 3.92 (s, 4H, -CH2-), 6.35 (d, 2H, J ϭ
7.8 Hz, Ar), 6.68 (s, 8H, Ar), 6.97 (t, 1H, J ϭ 7.6 Hz, Ar); MS
(EI): m/z 643 (Mϩ, 100 %); mp: 184 °C; elemental analysis
(C43H51NP2): cal.: C: 80.22, H: 7.98, N: 2.18, found: C: 79.88, H:
7.96 , N: 2.09 %.
Complexes 1-FeCl2, 2-FeCl2, 3-FeCl2, 2-CoCl2, 3-CoCl2: The appro-
priate anhydrous metal salt (2 mmol), dissolved in 20 ml of ethanol,
was added to the appropriate ligand (2 mmol) in 30 ml of CH2Cl2.
The reaction mixture was stirred overnight and the precipitated
2844
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846

Iron and Cobalt Complexes of a Series of Tridentate P,N,P Ligands
product was separated, washed with ethanol and diethyl ether and
dried in vacuum. Yield: 70Ϫ90 %.
the labelling scheme: ORTEP3 (Farrugia, 1997) [29, 30].The struc-
tures were solved by direct methods. All non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were refined on calculated
positions. The displacement factor of the H-atoms was 1.2 ϫ (or
1.5 ϫ for methyl hydrogens) to that of the host atom5).
1-FeCl2: MS (FAB): m/z 601 (Mϩ, 35 %, 35Cl), 566 (Mϩ-Cl, 100 %,
35Cl) (TMAP/DMF 1:1); mp: 210 °C (dec.); elemental analysis
(C31H27Cl2FeNP2): cal.: C: 61.82, H: 4.52, N: 2.33, found: C: 60.91,
H: 4.50, N: 2.25 %.
2-FeCl2: MS (FAB): m/z 657 (Mϩ, 45 %, 35Cl), 622 (Mϩ-Cl, 100 %,
35Cl) (TMAP/DMF, 2:1); mp: 215°C (dec.); elemental analysis
(C35H35Cl2FeNP2): cal.: C: 63.85, H: 5.36, N: 2.13, found: C: 63.23,
H: 5.40, N: 2.04 %.
3-FeCl2: MS(FAB): m/z 769 (Mϩ, 65 %, 35Cl), 734 (Mϩ-Cl, 100 %,
35Cl) (TMAP/DMF; 1:1); mp: 178 °C (dec.); elemental analysis
(C43H51Cl2FeNP2 ϫ 1/2 CH2Cl2): cal.: C: 64.26, H: 6.45, N: 1.72,
found: C: 64.51, H: 6.46, N: 1.69 %.
Crystallographic data for the structural analysis have been de-
posited with the Cambridge Crystallographic Data Center, CCDC
181872 for compound 2, CCDC 181873 for compound 2-CoCl2,
CCDC 181874 for compound 3-CoCl2. Copies of this information
may be obtained free of charge from The Director, CCDC, 12 Un-
ion Road, Cambridge, CB2 1EZ UK, Fax: ϩ44-1223-336-033; E-
mail: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.a-
c.uk.
Acknowledgements. The Fonds der Chemischen Industrie and the
DAAD are gratefully acknowledged for their financial support.
1-CoCl2: MS (FAB): m/z 604 (Mϩ, 20 %, 35Cl), 569 (Mϩ-Cl, 100 %,
35Cl), (TMAP/DMF 2:1); mp: 275 °C (dec.); elemental analysis
(C31H27Cl2CoNP2): cal.: C: 61.51, H: 4.50, N: 2.31, found: C:
61.49, H: 4.69, N: 2.31 %; µeff ϭ 4.54 µB.
References
2-CoCl2: MS (FAB): m/z 660 (Mϩ, 30 %, 35Cl), 625 (Mϩ-Cl, 100 %,
35Cl) (TMAP/DMF, 2:1); mp: 265 °C, at 225 °C color change to
turquoise; elemental analysis (C35H35CoNP2FeCl2): cal.: C: 63.55,
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with ethene by pressurizing the autoclave with ethene and releasing
the pressure and the appropriate amount of MAO was added in
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Crystallography
Crystal data of compound 2 were collected on a Enraf-Nonius
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˚
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Solution and refinement: SHELX-97 (Sheldrick, 1997); figures with
5) The high R values for compound 2-CoCl2 and 3-CoCl2 can be
deduced to a disordered solvent molecule in the case of 2-CoCl2
and to poor crystal quality in the case of 3-CoCl2.
4) For the turquois isomer of 2-CoCl2 a magnetic moment of
4.40 µB was observed as well.
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846
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2846
Z. Anorg. Allg. Chem. 2002, 628, 2839Ϫ2846