Phosphanylalkylcyclopentadienyl ligands: Synthesis, molecular structures and catalytic properties of [{(η5-C5H 4)CMe2PHR}CrCl2(PMe2Ph)] (R=Ph, tBu)

Article abstract of DOI:10.1016/j.poly.2004.02.011

Li[(C₅H₄)CMe₂PHPh] reacted with [CrCl ₃(THF)₃] with formation of a mixture of products, among which only [{(η⁵-C₅H₄)CMe ₂PPh}CrCl]₂ (1) could be isolated. However, when [CrCl₃(PMe₂Ph)₃] was treated with Li[(C ₅H₄)CMe₂PHR], the complexes [{(η⁵-C₅H₄)CMe₂PHR}CrCl ₂(PMe₂Ph)] (R=Ph (2), ^tBu (3)) were obtained in moderate yield. Complexes 1 and 2 were characterised by X-ray crystallography, 1-3 by IR spectroscopy. In the solid state, a phosphanido-bridged dimer is observed for 1, while 2 and 3 are monomeric complexes without coordination of the phosphanyl group of the cyclopentadienyl ring. 2 and 3 were also characterised by mass spectrometry and NMR and UV-Vis spectroscopy, and their magnetic moments were determined. 2 and 3 were studied in the catalytic polymerisation of ethylene with methylalumoxane (MAO) as cocatalyst.

Full text of DOI:10.1016/j.poly.2004.02.011

Polyhedron 23 (2004) 1393–1399
www.elsevier.com/locate/poly
Phosphanylalkylcyclopentadienyl ligands: synthesis,
molecular structures and catalytic properties
of [{(g5-C5H4)CMe2PHR}CrCl2(PMe2Ph)] (R ¼ Ph, Bu)
t
a
Thomas Hocher , Brian A. Salisbury , Klaus H. Theopold , Evamarie Hey-Hawkins
b
b
a,
*
€
a
Institut fu€r Anorganische Chemie der Universit€at, Johannisallee 29, D-04103 Leipzig, Germany
Department of Chemistry and Biochemistry, Center for Catalytic Science and Technology, University of Delaware, Newark, DE 19716, USA
b
Received 5 January 2004; accepted 19 February 2004
Available online 12 April 2004
Abstract
Li[(C5H4)CMe2PHPh] reacted with [CrCl3(THF)3] with formation of a mixture of products, among which only [{(g5-
C5H4)CMe2PPh}CrCl]2 (1) could be isolated. However, when [CrCl3(PMe2Ph)3] was treated with Li[(C5H4)CMe2PHR], the
complexes [{(g5-C5H4)CMe2PHR}CrCl2(PMe2Ph)] (R ¼ Ph (2), tBu (3)) were obtained in moderate yield. Complexes 1 and 2 were
characterised by X-ray crystallography, 1–3 by IR spectroscopy. In the solid state, a phosphanido-bridged dimer is observed for 1,
while 2 and 3 are monomeric complexes without coordination of the phosphanyl group of the cyclopentadienyl ring. 2 and 3 were
also characterised by mass spectrometry and NMR and UV–Vis spectroscopy, and their magnetic moments were determined. 2 and
3 were studied in the catalytic polymerisation of ethylene with methylalumoxane (MAO) as cocatalyst.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Phosphanylalkylcyclopentadienyl ligands; Chromium complexes; Polymerisation studies
1. Introduction
While numerous cyclopentadienyl ligands with O-
and N-functionalised side chains are known, the number
of cyclopentadienes with a P-functionalised alkyl or silyl
side chain is still small [8], and it was only in 1994 that
Heidemann and Jutzi [9] reported the first compound in
which the P atom bears a reactive P–H bond. We ex-
tended this class of compounds to other derivatives in
1999 [10,11]. The lithium salts [Li(TMEDA)]2[(C5H4)-
CMe2PPh] [12] and [Li(TMEDA)][(C5H4)CMe2PR2]
(R ¼ Ph, Me) [13], 1-SiMe2PHMes*C5Me4H and its
dimeric dipotassium salt [K(THF)2]2[(C5Me4)SiMe2-
PMes*] (Mes* ¼ 2,4,6-tBu3C6H2) [14] have been struc-
turally characterised. Such compounds should be useful
precursors for dianionic bifunctional ligands in transi-
tion metal chemistry. In addition, the presence of a P-
containing group is advantageous for reactivity studies
by 31P NMR spectroscopy.
After the discovery of a-olefin polymerisation [1],
numerous metallocene and monocyclopentadienyl de-
rivatives with different steric and electronic properties
were synthesised and employed as catalysts in poly-
merisation reactions. Ansa-metallocene dichlorides of
Ti, Zr, and Hf (especially chiral ones) are important
catalysts for the methylalumoxane-promoted isotactic
polymerisation of olefins. Therefore, intensive research
is being carried out towards the synthesis of improved
catalysts [2–5]. Recently, monocyclopentadienyl deriva-
tives in which the cyclopentadienyl ring has a heteroat-
om-functionalised side chain were prepared and
employed in the polymerisation and copolymerisation of
olefins [6]. These studies were also extended to phos-
pholyl ligands [7].
We previously reported the synthesis of the PH-
functionalised ferrocene derivatives rac-[Fe{(g5-
C5H4)CMe2PHR}2] [R ¼ Ph, 2,4,6-Me3C6H2 (Mes)] [15]
the monosubstituted phosphanylalkylcyclopentadienyl
* Corresponding author. Tel.: +493419736151; fax: +493419739319.
E-mail address: hey@rz.uni-leipzig.de (E. Hey-Hawkins).
0277-5387/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.02.011

1394
T. H€ocher et al. / Polyhedron 23 (2004) 1393–1399
complexes of group 4 metals, [{(g5-C5H4)SiMe2PHR}-
ZrCl3] (R ¼ Ph, Cy) and [{(g5-C5H4)CMe2PHtBu}-
MCl3] (M ¼ Ti, Zr) [16] and of the metallocene
derivatives [{(g5-C5H4)CMe2PHR}2ZrCl2] and [{(g5-
presence of a PH band at 2289 cmꢀ1 in the IR spectrum
of the pale blue powder indicates that a mixture of
products was obtained. The other product(s) could,
however, not be obtained in pure form by fractional
crystallisation, extraction or thin-layer chromatography.
The formation of 6,6-dimethylfulvene in the reaction
mixture, shown by 1H NMR spectroscopy, indicated
decomposition of the phosphanylalkylcyclopentadienyl
ligand. Similarly, decomposition of Li[(C5H4)C-
Me2PHPh] was observed on protonation with HCl gas
in diethyl ether (formation of PH2Ph, LiCl and 6,6-
dimethylfulvene) and in reactions with AlCl3, for which
elimination of HCl is proposed as the first reaction step
[21]. A similar reaction is proposed here, with attack of
CrCl3 on the cyclopentadienyl ring (with elimination of
LiCl) and/or at the phosphanyl group (with elimination
of HCl).
t
C5H4)CMe2PHR}2TiCl] (R ¼ Ph, Bu). The last-named
slowly decompose on recrystallisation from THF, Et2O
or toluene with formation of [{(g5-C5H4)2CMe2}MCl2]
(M ¼ Zr, Ti) and (PR)n (R ¼ Ph, n ¼ 4–6, R ¼ tBu,
n ¼ 4) and PH2R [17]. Recently, Erker and coworkers
[18] reported the synthesis and catalytic properties in the
polymerisation of olefins of the constrained-geometry
catalysts
[{(C5H4)CMe2PCy}M(NR2)2]
(M ¼ Ti,
R ¼ Me, M ¼ Zr, R ¼ Et). Hou and coworkers [14]
reported the synthesis of [{(g5-C5Me4)SiMe2PMes*}-
Ln(L)n] (Ln ¼ Sm: L ¼ THF, n ¼ 1 or 3; L ¼ MeOCH2-
CH2OMe, n ¼ 2; L ¼ PO(NMe2)3, n ¼ 2; Ln ¼ Yb,
L ¼ THF, n ¼ 3) and the polymerisation of ethene, e-
caprolactone and 1,3-butadiene with the SmII mono-
THF complex.
Activation of the PH proton and elimination of HCl
can be avoided if [CrCl3(PMe2Ph)3] is employed as
starting material, as this prevents attack at the phos-
phanyl group, as well as subsequent reactions after for-
mation of the cyclopentadienyl complexes, because
coordination of the phosphanyl group to chromium is
prevented. Dark green [CrCl3(PMe2Ph)3] is readily ob-
tained from the reaction of CrCl3 with three equivalents
of PMe2Ph in refluxing THF/toluene (if less PMe2Ph is
employed, unconsumed insoluble CrCl3 remains) [22].
After filtration, the solution of the phosphine complex
was treated in situ with a solution of Li[(C5H4)C-
Me2PHR] in THF at )50 °C, and the blue chromium(III)
We now report the synthesis and catalytic properties
of the first PH-functionalised phosphanylalkylcyclo-
pentadienyl complexes of chromium(III), [{(g5-
C5H4)CMe2PHR}CrCl2(PMe2Ph)] (R ¼ Ph (2), tBu (3)),
and the first constrained-geometry chromium complex
with a phosphanidoalkylcyclopentadienyl ligand, [{(g5-
C5H4)CMe2PPh}CrCl]2 (1).
Only a limited number of chromium complexes with
chelating tertiary phosphanylalkylcyclopentadienyl li-
gands is known [19]. [{(g5-C5H4)CH2CH2PR2}CrCl2]
(R ¼ Me, Et, Pr, iPr, iBu, tBu, neopentyl, hexyl, Cy, Ph,
o-tolyl, 1-naphthyl) are accessible from the corre-
sponding lithium cyclopentadienide and [CrCl3(THF)3]
[19]; reaction with MeLi and R0MgCl gave the corre-
sponding dimethyl and dialkyl derivatives (R0 ¼ Me, Pr,
complexes
[{(g5-C5H4)CMe2PHR}CrCl2(PMe2Ph)]
(R ¼ Ph (2), tBu (3)) were obtained in high yield
(Eq. (1)).
Crystals of 2 and 3 are only slowly oxidised in air,
while a blue solution of 3 in THF, toluene or CH2Cl2
slowly turns green on prolonged exposure to air. In the
IR spectra, complexes 2 and 3 exhibit a sharp PH ab-
sorption at 2278 (2) and 2276 cmꢀ1 (3). The 31P{1H}
NMR spectra (CH2Cl2/C6D6) show very broad signals
(m1=2 ca. 900 Hz) at 92 (2) and 111 ppm (3) (cf.
Li[(C5H4)CMe2PHR]: )1.2 ppm (R ¼ Ph) [10]), 26.0
ppm (R ¼ tBu) [17]. Typical of half-sandwich CrIII
complexes, the 1H NMR spectra of 2 and 3 (C6D6) show
several broad and isotropically shifted resonances
ranging in chemical shift approximately from +11 to
)30 ppm. Consistent with the structural similarity of 2
and 3, both spectra feature a series of very similar peaks,
namely, those at 10.5, 5.0, ca 0.0 and ca. )28 ppm. These
are likely associated with the PMe2Ph ligand and the
geminal methyl groups of the cyclopentadienyl sub-
stituent, although the greater signal intensity at 0.0 ppm
in 3 suggests accidental coincidence with the resonance
of the tert-butyl group. The spectrum of 2 exhibits a few
minor additional peaks, which are attributed to the P-
bound phenyl ring. In summary, the 1H NMR spectra of
paramagnetic organometallics can rarely be unambi-
t
Cy, Bu). The dichloride complex can be used with me-
thyl alumoxane (Al:Cr ¼ 100:1) as a catalyst for the
polymerisation of ethene [20].
2. Results and discussion
The lithium reagents Li[(C5H4)CMe2PHR] (R ¼ Ph
[10], tBu [17]) are readily accessible by reaction of
LiPHR with 6,6-dimethylfulvene. The reaction of
Li[(C5H4)CMe2PHPh] with [CrCl3(THF)3] yielded a
pale blue powder, from which a small amount of blue
crystals of [{(g5-C5H4)CMe2PPh}CrCl]2 (1) was ob-
tained on recrystallisation from toluene/hexane (Eq.
(1)). Attempts to synthesise 1 in better yield (a) by
heating to reflux after addition of Li[(C5H4)CMe2PHPh]
to [CrCl3(THF)3]; (b) by reaction of [{(g5-C5H4)CMe2-
PHPh}CrCl2(PMe2Ph)] with DBU (DBU ¼ 1,8-diaza-
bicyclo[5.4.0]undec-7-ene); or (c) by reaction of
Li[(C5H4)CMe2PHPh] with [CrCl3(THF)3] in the pres-
ence of DBU failed. The molecular structure (vide infra)
shows a phosphanido-bridged dimer. However, the

T. H€ocher et al. / Polyhedron 23 (2004) 1393–1399
1395
Me Me
Ph
Cl
P
+ ?
Cr
Cr
+ [CrCl3(THF)3]
(R = Ph)
P
Cl
Ph
Me Me
Li[(C5H4)CMe2PHR]
ð1Þ
Me
Me
+ [CrCl3(PMe2Ph)3]
(R = Ph, tBu)
PHR
Cr
Cl
R = Ph (2), tBu (3)
PhMe2P
Cl
gously assigned. However, the spectra of 2 and 3 clearly
show them to be closely related and are entirely con-
sistent with the crystal structures. The cyclopentadienyl
protons are probably too far shifted and broadened to
be readily detectable.
phenyl rings form an angle of 35.8°. The chromium
atom, C1 of the cyclopentadienyl ring, C12 of the
methylene bridge and P1 form a planar four-membered
ring; this plane forms an angle of 54.8(1)° with the Cr2P2
ring (see Fig. 1).
In the UV–Vis spectra the blue complexes 2 and 3
show absorptions at k ¼ 661 (log(e/cm2 molꢀ1) ¼ 4.69)
and 667 nm (log(e/cm2 molꢀ1) ¼ 4.72), respectively.
No meaningful mass spectrum was obtained for 2,
while for 3, a molecular ion peak as well as fragmenta-
tion products thereof were observed in the FAB mass
spectrum.
There are two independent molecules in the asym-
metric unit of 2, which differ mainly in the configuration
of the chiral P atoms, P1 and P3. One has R, and the
other S configuration (see Fig. 2).
In 1, the Cr–P bond is 0.09 A shorter than the coor-
dinative Cr–P(PMe2Ph) bond in 2 (2.439(1) and 2.447(1)
ꢁ
ꢁ
A). Similar Cr–P bond lengths are observed in the
phosphanido-bridged complexes [{(g5-C5Me5)Cr}2(l-
2.1. Molecular structures of 1 and 2
C14
Crystals of 2 suitable for X-ray crystallography were
obtained from a concentrated solution in diethyl ether at
)30 °C. Compound 3 crystallises in very thin plates re-
gardless of the solvent used for crystallisation. There-
fore, only a poor data set was obtained, but it was
sufficient to elucidate the structural motif, which is
similar to that of 2.
Compounds 1 and 3 crystallise in the monoclinic
space group P21=c with 2 and 8 formula units in the unit
cell, respectively; 2 crystallises in the triclinic space
C13
C12
C9
C7
C10
C6
Cl1
C8
C11
P1
Cr1
C5
C4
ꢀ
group P1 with 4 formula units in the unit cell.
C1
In 1, the centre of the Cr2P2 ring coincides with a
crystallographic centre of inversion. The Cr2P2 ring
forms a parallelogram with a Crꢁ ꢁ ꢁCr distance of
C3
C2
Fig. 1. Molecular structure of [{(g-C5H4)CMe2PPh}CrCl]2 (1) show-
ing the atom-numbering scheme employed (ORTEP plot, 50% proba-
bility, SHELXTL PLUS; XP [26]). Hydrogen atoms are omitted for
clarity.
ꢁ
2.9383(1) A and a P–Cr–P bond angle of 102.75(2)°
(Table 1). The cyclopentadienyl ring and the Cr2P2 ring
form an angle of 32.4(1)°; the cyclopentadienyl and

1396
T. H€ocher et al. / Polyhedron 23 (2004) 1393–1399
C33
(R ¼ Ph)) [19]. The different environment of Cr in 1 and 2
has only minor influence on the Cr–C (cyclopentadienyl
ring) and Cr–Cl distances (see Table 1).
C34
C35
C36
C32
C31
C25
C26
C24
C44
C43
C42
Hp2
C23
C38
P4
2.2. Ethylene polymerisation catalysis
C39
C40
C27
P3
Cr2
C28
C29
Cyclopentadienyl chromium(III) complexes are
known to catalyse the polymerization of ethylene, and in
view of the structural novelty of the complexes described
above their catalytic activity was evaluated. 10 mg of
chromium compound and 100 equivalents of methyl-
alumoxane (MAO) were dissolved in 50 ml toluene ([Cr]
ꢂ 10ꢀ6 M) and exposed to 1.4 MPa of ethylene for 1 h at
room temperature. Under these conditions both 2 and 3
produced moderate amounts of polyethylene (2, 0.54 g;
3, 1.38 g). Characterisation of the resulting polymers by
13C NMR spectroscopy showed them to be highly linear
polyethylene with negligible branching (2, 0.9 branches
per 1000 backbone C atoms; 3, 1.9 branches per 1000
backbone C atoms). However, molecular weight deter-
mination by gel permeation chromatography (GPC)
revealed a surprising difference between the two sam-
ples. Polyethylene obtained with 3 had a very narrow
molecular weight distribution (Mn ¼ 2220, Mw ¼ 4710,
Mw=Mn ¼ 2:12), consistent with a homogeneous single-
site catalyst. In contrast, the polymer produced by 2 was
at least trimodal and accordingly had a much higher
C41
C37
Cl3
C30
C13
C14
Cl4
C12
C11
C10
C2
C22
C9
C21
C20
C15
C4
Hp1
C6
C3
C17
C5
Cr1
P2
P1
C4
C19
C18
Cl2
C8
C9
C16
Cl1
Fig. 2. Molecular structure of [{(g5-C5H4)CMe2PHPh}CrCl2-
(PMe2Ph)] (2) showing the atom-numbering scheme employed (ORTEP
plot, 50% probability, SHELXTL PLUS; XP [26]). Hydrogen atoms
(other than PH) are omitted for clarity. There are two independent
molecules in the unit cell.
þ
ꢁ
PPh2)n(l-Cl)3ꢀn
]
(n ¼ 1, 2; Cr–P 2.385(2)–2.404(4) A)
[23] and the phosphine complexes [{(g5-C5H4)CH2-
ꢁ
CH2PR2}CrCl2] (2.459(1) (R ¼ Cy), 2.447(1)
A
Table 1
ꢁ
Selected distances [A] and bond angles [°] for 1 and 2
[{(g-C5H4)CMe2PPh}CrCl]2 (1)
Cr(1)–C
2.203(2)–2.255(2)
2.347(1)
2.360(1)
C(6)–P(1)–C(12)
C(1)–Cr(1)–P(1)
Cl(1)–Cr(1)–P(1)
P(1)–Cr(1)–P(1a)
C(6)–P(1)–Cr(1)
C(12)–P(1)–Cr(1)
C(1a)1–C(12)–P(1)
107.9(1)
126.23(5)
103.47(2)
102.75(2)
121.43(6)
126.05(6)
93.2(1)
Cr(1)–P(1)
Cr(1)–P(1a)
Cr(1)ꢁ ꢁ ꢁCr(1a)
P(1)–Cr(1a)
P(1)–C(6)
2.9383(1)
2.360(1)
1.817(2)
P(1)–C(12)
Cr(1)–Cl(1)
1.894(2)
2.278(1)
P(1)ꢁ ꢁ ꢁP(1a)
3.678(1)
[{(g5-C5H4)CMe2PHPh}CrCl2(PMe2Ph)] (2)
Molecule 1
Molecule 2
Cr(1)–C
Cr(1)–Cl
2.191(3)–2.282(3)
Cr(2)–C
Cr(2)–Cl
2.209(3)–2.290(3)
2.288(1)–2.290(1)
2.447(1)
2.278(1)–2.292(1)
2.439(1)
1.910(4)
Cr(1)–P(2)
P(1)–C(6)
P(1)–H(p1)
Cr(2)–P(4)
P(3)–C(28)
P(3)–H(p2)
1.895(3)
1.34(4)
1.36(4)
C(9)–P(1)–C(6)
104.1(2)
101.1(2)
98.2(2)
C(31)–P(3)–C(28)
C(31)–P(3)–H(p2)
C(28)–P(3)–H(p2)
C(38)–P(4)–C(37)
C(38)–P(4)–C(39)
C(37)–P(4)–C(39)
C(39)–P(4)–Cr(2)
C(38)–P(4)–Cr(2)
C(37)–P(4)–Cr(2)
Cl(4)–Cr(2)–Cl(3)
Cl(4)–Cr(2)–P(4)
Cl(3)–Cr(2)–P(4)
104.6(1)
101.2(1)
98.8(2)
C(9)–P(1)–H(p1)
C(6)–P(1)–H(p1)
C(16)–P(2)–C(17)
C(15)–P(2)–C(16)
C(15)–P(2)–C(17)
C(15)–P(2)–Cr(1)
C(16)–P(2)–Cr(1)
C(17)–P(2)–Cr(1)
Cl(1)–Cr(1)–Cl(2)
Cl(1)–Cr(1)–P(2)
Cl(2)–Cr(1)–P(2)
103.2(2)
103.9(2)
105.9(2)
113.7(1)
112.1(1)
116.7(1)
97.97(4)
92.94(4)
89.61(4)
104.2(2)
106.0(2)
104.6(2)
115.59(1)
113.6(2)
111.9(1)
97.5(1)
92.7(1)
91.4(1)

T. H€ocher et al. / Polyhedron 23 (2004) 1393–1399
1397
polydispersity (Mn ¼4830, Mw ¼617000, Mw=Mn ¼127:8).
The reasons for this disparity are not clear, given the
subtle structural differences between the two catalyst
precursors.
complete. The solution was filtered and the filtrate cooled
to )50 °C. A solution of Li[(C5H4)CMe2PHPh] (1.7 g,
7.6 mmol) in THF (25 ml) was slowly added to this so-
lution. During the addition, the initially green solution
turned blue. The solution was stirred for 12 h at r.t. Then
the solvent was evaporated in vacuo and the blue residue
dissolved in CH2Cl2 (25 ml). LiCl was separated from the
blue solution by filtration and extracted twice with
CH2Cl2 (10 ml). The CH2Cl2 fractions were combined
and the solvent was evaporated in vacuum. The blue
residue was washed with hexane (2 ꢃ 20 ml) and ex-
tracted repeatedly with Et2O (70 ml) to give 1.8 g (50%)
of 2; m.p. 114–117 °C. Blue crystals were obtained from a
concentrated Et2O solution at )30 °C.
3. Experimental
3.1. General
All experiments were carried out under purified dry
nitrogen. Solvents were dried and freshly distilled under
argon. The NMR spectra were recorded with an
1
AVANCE DRX 400 spectrometer (Bruker): H NMR
(400.13 MHz): internal standard solvent, external stan-
dard TMS; 31P NMR (161.9 MHz): external standard
85% H3PO4. The IR spectra were recorded on an FT-IR
spectrometer Perkin–Elmer System 2000 (KBr) in the
range 350–4000 cmꢀ1. UV–Vis spectra were recorded
with a LAMBDA 900 (Perkin–Elmer). The magnetic
moments were determined with a magnetic susceptibility
balance of Johnson Mathey Alfa Products. EI MS:
MAT 212 (Varian); FAB: ZAB-HSQ-VG Analytical
Manchester. The melting points were determined in
sealed capillaries under nitrogen and are uncorrected
(Boetius). Li[(C5H4)CMe2PHPh] [10] Li[(C5H4)CMe2-
PHtBu] [17] and [CrCl3(PMe2Ph)3] [24] were prepared
according to the literature procedures. CrCl3 is com-
mercially available (Merck).
1H NMR (C6D6): d ¼ ꢀ28:3 (br s), 0.3 (s), 4.5 (sh),
5.0 (s), 5.8 (s), 10.5 (s). 31P NMR (CH2Cl2/C6D6):
d ¼ 92 ppm. IR: 3076 (w, CH, C5H4), 3054 (w, CH, Ph),
2964, 2910 (m, CH, CH3 (CMe)), 2866 (w, CH, CH3
(PMe)), 2278 (m, PH), 1476, 1365 (m-st, CH3 (CMe)),
1435 (st, CH3 (PMe)), 1282, 1106 (w-m, PC (PMe2Ph),
955, 924, 829, 913 (st, CH, CH3 (PMe)) 745, 694 (st, CH,
Ph) 485 (m, PC (PMe2Ph)) cmꢀ1. UV–Vis: log(e/cm2
molꢀ1) ¼ 4.69 (k ¼ 661 nm). leff ¼ 4:0 B.M. (lcalc
¼
3:8). Anal. Calc. for C22H27Cl2CrP2 (476.3): C, 55.5; H,
5.7. Found: C 53.9, H 5.3%.
3.4. Synthesis of [{(g5-C5H4)CMe2PHtBu}CrCl2-
(PMe2Ph)] (3)
CrCl3 (1.3 g, 8.2 mmol) was suspended in toluene (25
ml), and THF (25 ml) and PMe2Ph (3.5 ml, 24.2 mmol)
were added quickly. The mixture slowly turned green
and was refluxed for ca. 2 h, after which the reaction was
complete. The solution was filtered and the filtrate
cooled to )50 °C. A solution of Li[(C5H4)CMe2PHtBu]
(1.65 g, 8.2 mmol) in THF (10 ml) was slowly added to
this solution. During the addition, the initially green
solution turned blue. The solution was stirred at r.t. for
2 h and then refluxed for 1 h. Then the solvent was
evaporated in vacuum and the blue residue dissolved in
CH2Cl2 (25 ml). LiCl was separated from the blue so-
lution by filtration and extracted twice with CH2Cl2 (10
ml). The CH2Cl2 fractions were combined and the sol-
vent was evaporated in vacuum. The blue residue was
washed with hexane (2 ꢃ 25 ml) and extracted repeatedly
with Et2O (50 ml) to give 1.9 g (51%) of 3 as blue
crystals; m.p. 143 °C.
3.2. Synthesis of [{(g-C5H4)CMe2PPh}CrCl]2 (1)
At ca. )50 °C a solution of Li[(C5H4)CMe2PHPh]
(1.7 g, 7.7 mmol) in THF (10 ml) was slowly added to a
suspension of [CrCl3(THF)3] (2.9 g, 7.7 mmol) in THF
(25 ml). During the addition, [CrCl3(THF)3] slowly
dissolved, and the initially colorless solution turned dark
green after addition of several drops of the solution of
the Li salt. The solution was stirred for 24 h at r.t., after
which it had turned blue. Then the solvent was evapo-
rated in vacuum and the slimy blue residue was washed
with n-hexane to give 2.0 g of a blue powder after drying
in vacuo. The blue powder was dissolved in toluene (15
ml) and layered with n-hexane. A blue powder was ob-
tained and a small amount of blue crystals of 1 suitable
for X-ray structure determination formed at the inter-
face between the two solvents.
1H NMR (C6D6): d ¼ ꢀ28:3 (br s), 0.0 (s), 5.0 (s), 8.9
(br s), 10.5 (s). 31P NMR (CH2Cl2/C6D6): d ¼ 111 ppm.
IR: 3080 (w, CH, C5H4), 3054 (w, CH, Ph), 2953, 2892
(m-st, CH, CH3 (CMe)), 2859 (m-st, CH, CH3 (PMe)),
2295, 2276 (m, PH), 1474, 1365 (m-st, CH3 (CMe)), 1436
(m-st, CH3 (PMe)), 1411 (m-st, CH3 (tBu)) 1280, 1107
(m, PC (PMe2Ph)), 955, 924, 829, 913 (st, CH, CH3
(PMe)) 744, 694 (st, CH, Ph) 485 (m, PC (PMe2Ph)), 408
3.3. Synthesis of [{(g5-C5H4)CMe2PHPh}CrCl2-
(PMe2Ph)] (2)
CrCl3 (1.2 g, 7.6 mmol) was suspended in toluene (25
ml), and THF (25 ml) and PMe2Ph (3.3 ml, 22.8 mmol)
were added quickly. The mixture slowly turned green
and was refluxed for ca. 2 h, after which the reaction was

1398
T. H€ocher et al. / Polyhedron 23 (2004) 1393–1399
Table 2
Crystal data and structure refinement for 1 and 2
data can be obtained free of charge via www.ccdc.cam.
ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44)-1223-336-033; or
deposit@ccdc.cam.uk).
1
2
Empirical formula
Mr
Temperature (K)
Crystal system
Space group
C28H30Cl2Cr2P2
603.36
220(2)
C22H27Cl2CrP2
476.30
220(2)
monoclinic
P21=c (no. 14)
8.7224(4)
8.9261(4)
17.0822(8)
90
triclinic
ꢀ
P1 (no. 2)
ꢁ
a (A)
13.738(2)
13.764(2)
13.885(2)
88.986(3)
72.509(3)
72.607(3)
2382.0(6)
4
Acknowledgements
ꢁ
b (A)
ꢁ
c (A)
We gratefully acknowledge financial support from the
Deutscher Akademischer Austauschdienst (315/PPP/ab)
and the US National Science Foundation (CHE-9876426
to KHT). We thank ChevronPhillips Chemical Co. for
characterisation of the polymers.
a (°)
b (°)
c (°)
96.4(1)
90
3
ꢁ
V (A )
1321.7(1)
2
1.516
Z
qcalc (Mg mꢀ3
F ð000Þ
)
1.328
988
620
0.70 ꢃ 0.20 ꢃ 0.05
1.162
Crystal size (mm)
Absorption coefficient
0.3 ꢃ 0.2 ꢃ 0.2
0.844
(mmꢀ1
)
References
H range (°)
2.35–28.74
13076
3239
1.56–29.45
15394
11272
0.0271
495
Reflections collected
Independent reflections
Rint
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0.0391
211
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Parameters
R½I > 2rIÞꢄ
0.0300
0.0756
0.306
0.0514
0.0999
0.312
wR2 (all datꢀa3)
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ꢁ
D=qmin (e Aꢀ3
)
ꢁ
D=qmax (e A
)
)0.313
)0.369
€
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420 (49) [Mþ ) Cl], 317 (25) [Mþ ) PMe2Ph], 282 (62)
[Mþ ) Cl ) PMe2Ph], 139 (100) [PMe2Ph + Hþ], and
fragmentation products thereof. EI MS: m/z ¼ 362
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€
(b) H.H. Brintzinger, D. Fischer, R. Mulhaupt, B. Rieger, R.M.
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[Mþ ) C6H5CH3],
317
[Mþ ) PMe2Ph],
281
€
(c) G. Fink, R. Mulhaupt, H.H. Brintzinger, Ziegler Catalysts –
[Mþ ) HCl ) PMe2Ph], 225 [Mþ ) HCl ) PMe2Ph ) tBu],
193 [Mþ ) PMe2Ph ) PHtBu ) Cl], 138 [PMe2Ph]þ, 123
[PMePh], and fragmentation products thereof. UV–Vis:
log(e/cm2 molꢀ1) ¼ 4.72 (k ¼ 667 nm). leff ¼ 3:8 B.M.
(lcalc ¼ 3:8). Anal. Calc. for C20H31Cl2CrP2 (456.3): C,
52.6; H, 6.8. Found: C, 52.0; H, 7.1%
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