Coordination chemistry of the activation of [(triazacyclohexane) CrCl3] with [PhNMe2H][B(C6 F5)4] and AlR3

Article abstract of DOI:10.1016/S0022-328X(03)00634-X

Complexes of N-substituted 1,3,5-triazacyclohexanes with CrCl₃ form 1:1 adducts with [PhNMe₂H][B(C₆F₅) ₄] with increased solubility in toluene. Addition of AlⁱBu₃ leads to free PhNMe₂ and a complex with [B(C₆F₅)₄]^- weakly coordinated to chromium via a meta-fluorine atom. This complex can polymerise and/or trimerise olefins similar to methyl aluminoxane activated complexes. Decomposition of the active complex involves transfer of the triazacyclohexane to aluminium leading to [(triazacyclohexane)AlⁱBu₂][B(C₆ F₅)₄] and [(arene)₂Cr][B(C₆ F₅)₄]. These chromium(I) complexes have been characterised by X-ray crystallography and prove that chromium is reduced to the oxidation state +I during the catalysis.

Full text of DOI:10.1016/S0022-328X(03)00634-X

Journal of Organometallic Chemistry 683 (2003) 200Á208
/
www.elsevier.com/locate/jorganchem
Coordination chemistry of the activation of
[(triazacyclohexane)CrCl3] with [PhNMe2H][B(C6F5)4] and AlR3
Randolf D. Kohn a,*, David Smith a, Mary F. Mahon a, Martina Prinz b,
¨
Shahram Mihan c, Gabriele Kociok-Kohn a
¨
a Department of Chemistry, University of Bath, Bath BA2 7AY, UK
b BASF AG, Research Laboratory, D-67056 Ludwigshafen, Germany
c Basell Polyolefins GmbH, Research Laboratory, D-67056 Ludwigshafen, Germany
Received 28 March 2003; received in revised form 26 June 2003; accepted 28 June 2003
Abstract
Complexes of N-substituted 1,3,5-triazacyclohexanes with CrCl3 form 1:1 adducts with [PhNMe2H][B(C6F5)4] with increased
solubility in toluene. Addition of Ali Bu3 leads to free PhNMe2 and a complex with [B(C6F5)4]ꢀ weakly coordinated to chromium
via a meta-fluorine atom. This complex can polymerise and/or trimerise olefins similar to methyl aluminoxane activated complexes.
Decomposition of the active complex involves transfer of the triazacyclohexane to aluminium leading to [(triazacyclohexane)
Ali Bu2][B(C6F5)4] and [(arene)2Cr][B(C6F5)4]. These chromium(I) complexes have been characterised by X-ray crystallography and
prove that chromium is reduced to the oxidation state ꢁI during the catalysis.
/
# 2003 Elsevier B.V. All rights reserved.
Keywords: Chromium; Olefin trimerisation; Arene complexes
1. Introduction
Alternatively, other alkylating agents like AlR3 in
combination with alkyl-abstracting agent like B(C6F5)3
or anilinium or trityl salts of weakly coordinating anions
like [B(C6F5)4]ꢀ can be used. These co-catalysts have
the advantage of producing well defined anions that
allow the spectroscopic or crystallographic investigation
of the catalysts.
Several transition metal systems have been found over
the past 50 years that can catalyse the polymerisation
and oligomerisation of olefins. Heterogeneous Ziegler-
Natta systems based on early transition metals are the
most successful and produce a large variety of poly-
olefins. Homogeneous single site systems, initially the
group IV metallocenes but later with many different
ligands and metals, have been developed which are able
to produce highly stereo regular polymers and have
become useful industrial catalysts. The study of these
homogeneous systems has tremendously improved the
detailed understanding of the catalytic mechanism.
Generally the transition metal complexes are treated
with a co-catalyst to become active. The most com-
monly used co-catalyst is methyl aluminoxane (MAO).
The heterogeneous Phillips catalysts [1Á5] based on
/
CrO3/SiO2 for the polymerisation of ethylene have been
known as long as the Ziegler-Natta systems and they
still produce a large fraction of the world production of
HDPE (ꢀ7 million ton per annum) [6,7]. This system
/
has many unusual features compared to the other
transition metal catalysts and little is known about its
active species and mechanism [8Á10]. After the initial
/
report by Briggs [11], some homogeneous chromium
systems have been developed that are able to catalyse
the unusual selective trimerisation of ethylene. These
systems generally consist of some soluble chromium
complex, aluminium alkyls and some amine, mostly
pyrroles [12] or more recently PNP ligands [13]. The
* Corresponding author. Tel.: ꢁ
38-6231.
E-mail address: r.d.kohn@bath.ac.uk (R.D. Kohn).
/
44-1225-38-3305; fax: ꢁ44-1225-
/
¨
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00634-X

R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
201
¨
increasing demand for 1-hexene has sparked a growing
interest in these selective trimerisation catalysts.
The much slower trimerisation of a-olefins especially
suffers from the relatively fast deactivation of the
system. To our knowledge, no alternative system is yet
known for the catalytic trimerisation of a-olefins.
Therefore, a detailed understanding of the activation
and deactivation processes is mandatory for the devel-
opment of better catalysts. Here we describe a detailed
investigation of the activation with DMAB/AliBu3 and
subsequent decomposition.
However, little is known about the active species in
these complex mixtures largely due to the difficulty of
obtaining useful NMR spectra of these highly para-
magnetic compounds. Briggs [11] and others have
proposed a mechanism via metallacycles analogous to
Scheme 2 and Jolly and co-workers [14] were able to
support the involvement of metallacyclopentane and
metallacycloheptane complexes. Although oxidative ad-
dition of the olefins and reductive elimination of the
trimer are required by this mechanism, no oxidation
2. Results and discussion
states of chromium other than ꢁIII have been proven in
/
the catalytic cycle, and redox steps via Cr(I)/Cr(III) or
Cr(II)/Cr(IV) have been proposed. A similar mechanism
has recently been found for titanium systems [15,16] or
TaCl3Me2 [17] and a recent computational study of the
latter system confirms a mechanism via metallacycles
and two oxidation states [18].
The activation by DMAB/AliBu3 is best performed in
two steps. First [(R3TAC)CrCl3] is treated with one
equivalent of DMAB in toluene or benzene. Even poorly
soluble chromium complexes dissolve readily upon the
addition of DMAB. This increased solubility greatly
enhances the catalytic performance of many complexes.
1H- and 13C-NMR spectra of these solutions show
severely broadened or unobservable signals for the
aniline and significant broadening of the 19F-NMR
For several years we have been investigating the
coordination chemistry of N-substituted 1,3,5-triazacy-
clohexanes (R3TAC) [19Á23]. Our results on the co-
/
ordination chemistry of R3TAC show that complexes
with low steric demand by the ligand and the misdir-
signals to 100Á300 Hz. This indicates an anilinium
adduct with a close contact to the paramagnetic
chromium and ion pairing with the anion. For the cases
/
ected nitrogen lone pairs due to the small NÁ
/
metalÁN
/
angle of 60Á658 can be formed.
/
Rꢂ
/
PhCH2CH2 (2a) and RꢂEt2CHCH2 (2b) crystals
/
The triazacyclohexane complexes of CrCl3 (Scheme 1)
can be activated with MAO [25] or [PhNMe2H]ꢁ
[B(C6F5)4]ꢀ (DMAB) followed by trialkylaluminium.
Depending on the substituents, the catalyst can poly-
merise or selectively trimerise ethylene and, for the first
time, also trimerise a-olefins. Activities of up to 800 kg
mol Crꢀ1 hꢀ1 with MAO or up to 2800 kg mol Crꢀ1
hꢀ1 with DMAB/AliBu3 can be obtained. Thus, the
activity is comparable to that of the heterogeneous
were grown from the solution and analysed by X-ray
crystallography. The crystal structure of 1a as the
precursor of the adduct was determined as well to
investigate the effect of the anilinium adduct. The
structures of 1a and the cations in 2a and 2b are shown
in Figs. 1Á3 and selected bond distances and angles are
/
given in Table 1.
Comparison of the data shows little significant change
in the coordination environment of chromium upon
adduct formation. More significantly the adduct forma-
tion changes the weak intermolecular hydrogen bonding
network. In 1a, contacts between hydrogen atoms of the
triazacyclohexane ring and chloride atoms of neighbour-
Phillips catalyst (500Á
3000 kg mol Crꢀ1 hꢀ1) and more
/
active chromium catalysts have only been obtained with
Cp-based systems [10,26] (up to 20 000 kg mol Crꢀ1
hꢀ1).
ing molecules are found (closest distance H3A
/
ꢀ ꢀ ꢀ
/
Cl1
A single mononuclear chromium(III) complex is
observed during the catalysis, probably a metallacyclo-
pentane complex. The observation of two broadened
and shifted signals in 2H-NMR studies with a ring-
deuterated ligand proves that the triazacyclohexane is
coordinated to the paramagnetic chromium in the active
complex. The kinetic data can be fitted to rate laws
derived from the metallacyclic mechanism outlined in
Scheme 2.
˚
2.84 A) (and slightly longer contacts to other hydrogen
atoms of neighbouring ligands) leading to an infinite
weak hydrogen bonding network. Similar contacts are
found in many other [(R3TAC)CrCl3] complexes [27]. In
the anilinium adduct 2a, two strong hydrogen bonds
˚
Cl1 2.52 A) form an isolated dinuclear unit (Fig.
(H1A/
ꢀ ꢀ ꢀ
/
2) with no additional H/ Cl contacts at distances
˚
smaller than 3 A. The bulkier N-substituents in 2b
prevent this close interaction and a zig-zag chain of
ꢀ ꢀ ꢀ
/
much weaker contacts is found (H1B/
ꢀ ꢀ ꢀ
/
Cl1 and H3B
/
ꢀ ꢀ ꢀ
/
˚
Cl3 both 2.91 A). Thus, engaging the chloride atoms in
an anilinium adduct weakens the intermolecular con-
tacts between the chromium complexes in the solid state
and may be the cause for the observed increased
solubility of the adducts.
Scheme 1. Syntheses of the complexes 1.

202
R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
¨
Scheme 2. Proposed mechanism for the selective trimerisation [24].
hexene indicating a similar anion coordination. How-
ever, the decomposition of the active chromium complex
leads to a sharpening of the 19F-NMR signals. This
process occurs within days without added 1-hexene and
within hours in the presence of 1-hexene. The meta-F
signal becomes detectable after 1 week (1 day in the
presence of 1-hexene) and yellow crystals separate from
the solution that analyse as [(arene)2Cr][B(C6F5)4]
(areneꢂ/benzene 3A or toluene 3B depending on the
solvent used). In repeated runs 10Á
/
20% of the chro-
mium were isolated in these crystals. The crystal
structures of d12-3A and 3B are shown in Fig. 4. The
˚
Fig. 1. Structure of 1a (disorder in one substituent not shown).
CrÃ
/
C bond distances (2.13Á
/
2.16 A for d12-3A and 2.10Á
/
˚
2.18 A for 3B) are similar to those found for the cations
in other [(arene)2Cr]ꢁ salts [28]. 3B has a disordered
cation with the major component having nearly eclipsed
methyl groups. This unusual conformation is probably
due to crystal packing.
Observation of the NMR spectra after addition of the
aluminium alkyl leads to the reappearance of narrow
aniline signals and disappearance of the m-F and severe
broadening of the o- and p-F signals. This is also
maintained after addition of 1-hexene and during
catalysis. Thus the anion fills a free coordination site
in the resting state of the activated catalyst (Scheme 3).
The observation of only no more than three 19F-NMR
signals in 2 and 3 indicates that fast exchange between
all o-, m- and p-F positions occurs on the NMR time
scale at ambient conditions leading to average line-
widths.
The observation of 3 proves that the oxidation state
ꢁI can be reached in the system and supports the
/
proposed mechanism via Cr(I). [(Arene)2Cr]ꢁ has pre-
viously been observed to about 0.4% in a mixture of
Cr(acac)3 and AlEt3 by ESR [29]. The much larger
amount of Cr(I) isolated in our system suggests that the
triazacyclohexane ligand may be involved in its forma-
1
tion. Close inspection of the H-NMR spectra of the
catalytic system after substantial decomposition shows
Initially, the linewidths of the ortho- and para-19F-
NMR signals are similar before and after addition of 1-
the appearance of two doublets in the region of 3Á4
/

R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
203
¨
Fig. 2. Structure of cation in 2a and a simplified plot of the neighbouring ions.
Table 1
˚
Selected bond distances (A) and angles (8)
1a
2a
2b
CrÃ
CrÃ
CrÃ
/
N1
N2
N3
2.0974(18)
2.1015(19)
2.1087(16)
2.103(6)
2.1162(14)
2.0826(14)
2.0983(14)
2.099(17)
2.1028(18)
2.1150(19)
2.0951(19)
2.104(10)
/
/
av. CrÃ
CrÃCl1
CrÃ
CrÃ
/
N
/
2.2853(6)
2.2791(6)
2.2658(7)
2.277(10)
2.2956(5)
2.2696(5)
2.2918(5)
2.286(14)
2.2928(7)
2.2826(7)
2.2818(6)
2.286(6)
/
Cl2
Cl3
/
av. CrÃ
Cl1Ã
Cl2/3Ã
av. NÃ
Cl1ÃCrÃ
Cl1ÃCrÃ
Cl2ÃCrÃ
av. ClÃ
av. CrÃ
/
Cl
/
H4
H4
CrÃ
2.65 a
2.60 a
2.74 a
2.59 a
/
/
/
N
66.2(5)
66.15(10)
99.901(19)
95.865(18)
99.697(19)
98.5(2.3)
66.2(2)
97.43(3)
98.38(2)
98.03(3)
97.9(5)
/
/
Cl2
Cl3
Cl3
97.84(3)
99.63(3)
99.60(3)
99.0(1.0)
/
/
/
/
/
CrÃ
/Cl
/
NÃCR
/
127.7(11.7)
126.2(2.4)
125.3(2.0)
Fig. 3. Structure of the cation in 2b.
a
Distances to hydrogens are based on the calculated positions in
the refinement.
ppm. The chemical shifts are different for different N-
substituents (4b,c). Similar doublets have previously
been observed for the two types of ring hydrogen atoms
in triazacyclohexanes coordinated in k3 fashion to
diamagnetic metal centres [30]. As Al(III) is the only
diamagnetic metal in the system, an aluminium complex
must have been formed. AliBu3 does not react with
R3TAC to form k3 complexes. However, when one
equivalent of DMAB is added, the previously observed
doublet pattern at nearly identical shifts confirm the
formation of [(R3TAC)AliBu2][B(C6F5)4] 4b,c. The
anion in the diamagnetic environment of 4 is in fast
exchange with the anions in remaining 3 resulting in
narrowing average linewidths for the 19F-NMR signals
with proceeding decomposition. Comparison of the
integrals for the aniline (one equivalent per chromium)
and the aluminium complex shows that at least 50% of
the original triazacyclohexane is transferred from the
chromium to aluminium. An approximate stoichiometry
of the decomposition that agrees with the observed
intensities is given in Scheme 4.
Transfer of the triazacyclohexane ligands from chro-
mium to aluminium on the Cr(I) stage of the proposed
cycle would lead directly to 3. However, some of the
triazacyclohexane must remain coordinated to an in-
active possibly multinuclear chromium(III) complex to
account for the previously observed new paramagneti-
cally shifted signals for coordinated ligand. We are
currently investigating the exact stoichiometry of the
decomposition and the nature of the other products.
3. Conclusion
Activation of [(triazacyclohexane)CrCl3] with DMAB
and AliBu3 leads to an active complex with similar

204
R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
¨
Scheme 3. Activation with DMAB/Ali Bu3.
catalytic olefin trimerisation activity as activation with
MAO. However, the well defined borate anion permits
isolation and crystallographic characterisation of hydro-
gen bonded anilinium adducts to the chromium chloride
complex during activation, and bis(arene) chromium(I)
complexes as catalyst decomposition products. This
observation shows that reduction to Cr(I) can occur in
this system. During catalysis itself, a cationic Cr(III)
complex with the weakly coordinating borate anion
occupying one coordination site is found to be the
resting state as shown by 19F-NMR.
and using Schlenk techniques. Solvents were dried
according to standard methods. CrCl3(THF)3 was
1
purchased from Aldrich. H-, 13C{1H}- and 19F-NMR
spectra were recorded on a Bruker 300 or Varian 400
instrument. [(n-Do3TAC)CrCl3] was prepared as de-
scribed previously [24].
4.1. Synthesis of (PhCH2CH2)3TAC [31]
(PhCH2CH2)3TAC was prepared analogously to
(Et2CHCH2)3TAC and repeatedly recrystallised from
hexane until a colourless solid was obtained in 62%
1
4. Experimental
yield. M.p. 38 8C; H-NMR (400 MHz): d(CDCl3) 7.38
(6H, m, m-Ph), 7.29 (9H, m, o, p-Ph), 3.52 (6H, br, NÃ
CH2 ÃN), 2.83 (12H, m, NÃ
CH2CH2Ph). 13C-NMR (75
MHz): d(CDCl3) 140.1 (i-Ph), 128.5, 128.1 (m, o-Ph),
/
All manipulations were carried out under nitrogen on
a standard vacuum line, argon in a Saffron glove box,
/
/
Fig. 4. Structure of the ions in 3A (left) and of the cation in the analogous 3B (right). Average CrÃ
/C bond distance in angstrom: 2.14 (3A) and 2.15
(3B).

R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
205
¨
Scheme 4. Proposed stoichiometry of the decomposition reaction (Rꢂ
/
Et2CHCH2 (2b) and Rꢂn-dodecyl (2c), arene solvent is C6D6 for 3A and
/
toluene for (3B).
125.7 (p-Ph), 74.2 (NÃ
/
CH2Ã
/
N), 54.2 (NÃ/CH2CH2Ph),
(18H, bs, CÃ
DMSO) 39.22 (6C, bs, CÃ
CH3).
/
CH3). 13C-NMR (100 MHz): d(CDCl3/
CH2ÃC), 12.98 (6C, bs, CÃ
34.3 (NÃCH2CH2Ph).
/
/
/
/
4.2. Synthesis of (Et2CHCH2)3TAC
4.5. Synthesis of [((PhCH2CH2)3TAC)CrCl3]
[DMAB] (2a)
2-Ethyl-n-butylamine (2 g, 19.8 mmol) and paraform-
aldehyde (0.59 g, 19.8 mmol) were stirred in toluene (20
ml). After 4 h, half the toluene and the water produced
during the reaction were removed by distillation. The
remaining solvent was removed in vacuo, resulting in a
colourless liquid of (Et2CHCH2)3TAC. Yield, 1.8 g
[((PhCH2CH2)3TAC)CrCl3] (0.1 g, 0.18 mmol) and
DMAB (0.144 g, 0.18 mmol) were stirred in toluene (10
ml) for 10 min. This solution was layered with hexane
(10 ml) and left to stand for 4 days. Filtration, repeated
washings with hexane and drying in vacuo resulted in
purple crystals of [((PhCH2CH2)3TAC)CrCl3(Ph-
Me2NH)][B(C6F5)4]. Yield, 0.14 g (57%), m.p. 251 8C
(dec.). Anal. Calc. for C48H57BCl3CrF20N4 (1366.09): C,
51.87; H, 3.32; N, 4.10. Found: C, 52.60; H, 3.37; N,
1
(80%). H-NMR (300 MHz): d(CDCl3) 3.26 (6H, br,
NÃ
1.32 (15H, m, CÃ
Hz, CH3). 13C-NMR (75 MHz): d(CDCl3) 75.8 (NÃ
CH2ÃN), 56.7 (NÃCH2ÃC), 39.2 (CH(CH2CH3)2),
24.7 (CH(CH2CH3)2), 11.3 (CÃCH(CH2CH3)2).
/
CH2Ã
/
N), 2.27 (6H, d, JH,H
ꢂ
/
5.3 Hz, NÃ
/
CH2 Ã
/
C),
7.2
/CH(CH2)2), 0.85 (18H, t, JH,H
ꢂ
/
/
/
/
/
/
4.21%. 19F-NMR (376 MHz): d(CDCl3) ꢀ
bs, o-ArF), ꢀ159.95 (4F, bs, p-ArF), ꢀ163.30 (8F, bs,
m-ArF).
/
130.48 (8F,
/
/
4.3. Synthesis of [((PhCH2CH2)3TAC)CrCl3] (1a)
(PhCH2CH2)3TAC (1.0 g, 2.5 mmol) and
CrCl3(THF)3 (1.0 g, 2.7 mmol) were stirred in THF
(20 ml) for 20 h. Addition of water, filtration, repeated
washings with first water and then Et2O and drying in
4.6. Synthesis of [((Et2CHCH2)3TAC)CrCl3]
[DMAB] (2b)
[((Et2CHCH2)3TAC)CrCl3] (0.1 g, 0.2 mmol) and
DMAB (0.161 g, 0.2 mmol) were stirred in toluene (10
ml) for 10 min. This solution was layered with hexane
(10 ml) and left to stand for 4 days. Filtration, repeated
washings with hexane then drying in vacuo resulted in
purple crystals of [((Et2CHCH2)3TAC)CrCl3(Ph-
Me2NH)][B(C6F5)4]. Yield, 0.19 g (71%), m.p. 234 8C
(dec.). Anal. Calc. for C53H57BCl3CrF20N4 (1299.18): C,
49.00; H, 4.42; N, 4.31. Found: C, 49.90; H, 4.34; N,
vacuo
resulted
in
a
purple
solid
of
((PhCH2CH2)3TAC)CrCl3. Yield, 1.3 g (93%), m.p.
285 8C (dec.). Anal. Calc. for C27H33Cl3CrN3 (557.93):
C, 58.12; H, 5.96; Cr 9.32; N, 7.53. Found: C, 57.92; H,
6.20; Cr 9.45; N, 7.87%. Solubility was too low for
NMR.
4.4. Synthesis of [((Et2CHCH2)3TAC)CrCl3] (1b)
1
4.02%. H-NMR (400 MHz): d(C6D6) 1.312 (12H, br,
CÃ
MHz): d(C6D6) 36.67 (6C, br, CÃ
br, CÃ
CH3). 19F-NMR (376 MHz): d(C6D6) ꢀ
Dn1/2 150 Hz, o-ArF), ꢀ162 (4F, Dn1/2 90 Hz, p-ArF),
165 (8F, Dn1/2 145 Hz, m-ArF).
/
CH2Ã
/
C), 0.933 (18H, br, CÃ
/
CH3). 13C-NMR (100
(Et2CHCH2)3TAC (1 g, 2.9 mmol) and CrCl3(THF)3
(1.103 g, 2.9 mmol) were stirred in THF (30 ml) for 12 h.
Filtration, repeated washings with Et2O then drying in
/
CH2Ã/C), 12.00 (6C,
/
/132 (8F,
/
vacuo
resulted
in
a
purple
solid
of
ꢀ
/
[((Et2CHCH2)3TAC)CrCl3]. Yield, 0.82 g (56%), m.p.
234 8C (dec.). Anal. Calc. for C21H45N3CrCl3 (497.96):
C, 50.65; H, 9.11; N, 8.44. Found: C, 50.10; H, 9.03; N,
8.21%. 1H-NMR (400 MHz): d(CDCl3/DMSO) 3.86
4.7. Synthesis of [(C7H8)2Cr] [B(C6F5)4] (3B)
(6H, bs, NÃ
/
CH2Ã
/
N), 1.96 (6H, bs, NÃ
/
CH2Ã
/
C), 1.67
C), 0.91
[(n-Do3TAC)CrCl3] (0.4 g, 0.5 mmol) and DMAB
(0.426 g, 0.5 mmol) were stirred in toluene (5 ml) for 5
(3H, bs, CÃCHÃ
/
/
[C]2), 1.30 (12H, bs, CÃ
/
CH2Ã
/

206
R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
¨
min. To this solution was added AliBu3 as 1.0 M
solution in hexane (2.5 g, 3.6 mmol). The resulting
1H-NMR of the solution also shows two small doublets
at 3.60 and 3.05 ppm (Jꢂ
/
9 Hz, ring CH2 of the
green solution was left to stand at ꢀ14 8C for 3 days
/
aluminium complex).
upon which yellow crystals of [(C7H8)2Cr] [B(C6F5)4]
were formed. Yield, 0.06 g (12%). Anal. Calc. for
C38H16BCrF20 (922.25): C, 49.86; H, 1.76; N, 0.0.
Found: C, 49.90; H, 2.10; N, 0.12%.
4.9. NMR-tube reaction of [(n-Do3TAC)CrCl3] (1c)
with DMAB, AliBu3 and 1-hexene and crystallisation of
3A
4.8. NMR-tube reaction of
[((Et2CHCH2)3TAC)CrCl3] [DMAB] (2b) with
AliBu3/1-hexene
[(n-Do3TAC)CrCl3] (6 mg, 0.008 mmol) and DMAB
(9 mg, 0.011 mmol) were dissolved in C6D6 (1 ml). 19F-
NMR (376 MHz): d(C6D6) ꢀ132 (8F, Dn1/2 225 Hz, o-
/
ArF), ꢀ162 (4F, Dn1/2 155 Hz, p-ArF), ꢀ
/
/
165 (8F, Dn1/2
[((Et2CHCH2)3TAC)CrCl3] [DMAB] (1.4 mg, 0.0011
mmol) were dissolved in C6D6 (1 ml) and 43 ml AliBu3 as
1.0 M solution in hexane (0.044 mmol) was added.
NMR of the resulting green solution 10 min after the
addition showed in the H-NMR isobutylene (4.8 ppm)
and DMA (7.0, 6.9 and 2.3 ppm) and in the 19F-NMR
231 Hz, m-ArF). To this solution was added 55 ml
AliBu3 as 1.0 M solution in hexane (0.055 mmol) and 27
mg 1-hexene (0.32 mmol). NMR of the resulting green
solution 10 min after the addition showed 1-hexene in
the 1H-NMR (5.9 and 5.1 ppm) and 19F-NMR (376
1
MHz): d(C6D6) ꢀ
/
130 (8F, Dn1/2 540 Hz, o-ArF), ꢀ
/
158
(376 MHz): d(C6D6) ꢀ
/
132 (8F, Dn1/2 207 Hz, o-ArF),
(4F, Dn1/2 870 Hz, p-ArF). After 2 days a mixture of
hexene trimers [24] has formed with 60% conversion by
integration of the olefinic region and yellow crystals of
3A have separated from the solution. Anal. Calc. for
C36D12BCrF20 (899.33): C, 48.08; H, 1.34 [32]; N, 0.0.
ꢀ160 (8F, Dn1/2 2000 Hz, m-ArF), ꢀ
/
/
162 (4F, Dn1/2 90
Hz, p-ArF). 1-Hexene (20 mg, 0.24 mmol) was added
and left to trimerise and decompose for 1 day. A mixture
of hexene trimers [24] has formed with 75% conversion
and yellow crystals have separated from the solution.
1
Found: C, 48.50; H, 1.58; N, 0.22%. H-NMR of the
Table 2
Summary of crystallographic data for compounds 1a, 2a, 2b, 3A and 3B
Compound
1a
2a
2b*(toluene)0.5
3A*(C6D6)0.5
3B*(toluene)0.5
Empirical formula
M (g molꢀ1
C27H33Cl3CrN3
557.91
Purple
C59H45BCl3CrF20N4
1359.15
Purple
C56.5H60.5BCl3CrF20N4
1344.75
Purple
C39H15BCrF20
926.32
Yellow
C41.5H19.5BCrF20
960.88
Yellow
)
Crystal colour
Crystal size (mm)
Crystal system
Space group
0.5ꢃ
/
0.15ꢃ
/
0.08
0.38ꢃ
/
0.25ꢃ
/
0.10
0.5ꢃ
/
0.4ꢃ
/
0.15
0.38ꢃ/0.13ꢃ/0.03
0.3ꢃ
/
0.25ꢃ0.13
/
Monoclinic
Triclinic
¯
1 (no. 2)
Monoclinic
Triclinic
¯
1 (no. 2)
Monoclinic
P21/c (no. 14)
11.6360(2)
17.1910(3)
14.0810(3)
P
/
P21/n (no. 14)
12.3190(1)
30.5470(3)
P
/
P21/c (no. 14)
10.4850(2)
21.8690(4)
16.8810(4)
˚
a (A)
13.4030(2)
15.0830(2)
15.2570(2)
63.8900(6)
82.3890(6)
80.4760(6)
2903.81(7)
2
8.1330(2)
13.3590(3)
16.2770(4)
107.1960(11)
97.2240(11)
93.3740(13)
1667.39(7)
2
˚
b (A)
˚
c (A)
16.5740(2)
a (8)
b (8)
g (8)
V (A )
Z
Dcalc (g cmꢀ3
109.784(1)
107.870(10)
103.971(1)
3
˚
2650.43(9)
4
5936.14(10)
4
3756.25(13)
4
)
1.398
0.755
1.554
0.443
1.505
0.432
1.845
0.489
1.699
0.437
m(MoÁ
/
Ka) (mmꢀ1
)
2u Range (8)
Collected data
8Á
/
55
7Á
/
55
6Á
/
54
6Á
/
55
7Á55
/
45 752
6064 (Rint
321
41 201
13 271 (Rint
793
41 284
12 904 (Rint
775
25 661
7625 (Rint
550
27 245
8310 (Rint
660
Unique Data (I ꢀ
Refined parameter
/
2sI)
ꢂ/0.074)
ꢂ/
0.041)
ꢂ/0.063)
ꢂ/0.079)
ꢂ/0.074)
ꢀ3
˚
Min/max density (e A
Extinction coefficient a
)
ꢀ
/
0.504/0.378
ꢀ
/
0.487/0.271
ꢀ
/
0.677/0.456
ꢀ
/
0.585/0.303
ꢀ/0.475/0.299
0.0054(7)
0.0396
0.0865
1.019
b
R1 (I ꢀ
/
2sI)
0.0358
0.0857
1.022
0.0441
0.0984
1.015
0.0443
0.0905
1.020
0.516
0.1138
1.011
c
wR2 (I ꢀ2sI)
Goodness-of-fit d
/
a
Fc ꢄ ꢂ
/
kFc[1ꢁ
ajjFojꢀjFcjj/ajFoj.
wR2ꢂ
{a[w(Fo2ꢀFc2)2]/a[w(F2o)2]}1/2
GOFꢂSꢂ
{a[w(F2oꢀF2c)2]/(nꢀp)}1/2
/
0.001F2cl3/sin(2u)]ꢀ1/4
.
b
c
R1ꢂ
/
/
/
/
.
d
/
/
/
/
.

R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
207
¨
solution also shows two small doublets at 3.48 and 2.93
ppm (ring CH2 of the aluminium complex).
1EZ, UK (fax: ꢁ44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk
/
4.10. NMR-tube synthesis of
[((Et2CHCH2)3TAC)AliBu2] [B(C6F5)4] (4b)
Acknowledgements
(Et2CHCH2)3TAC (0.032 g, 0.094 mmol), DMAB
(0.075 g, 0.094 mmol), and AliBu3 as 1.0 M solution in
hexane (0.29 g, 0.29 mmol) were dissolved in benzene-d6
R.D. Kohn and D. Smith thank EPSRC for support.
¨
The authors thank BASF AG and Basell for encourage-
ment and support.
(1 ml) to form
[((Et2CHCH2)3TAC)AliBu2] [B(C6F5)4] 4b. 1H-NMR
(300 MHz): d(C6D6) 3.73 (3H, d, JHa,Hb
8.9 Hz, NÃ
CHaHbÃN), 3.08 (3H, d, JHb,Ha 8.9 Hz, NÃCHbHaÃ
N), 1.70 (2H, m, CÃCHÃC), 0.92 (12H, d, JH,H 6.4
Hz, CÃCH3), 0.24 (4H, d, JH,H 7.0 Hz, AlÃCH2ÃC).
a
colourless solution of
ꢂ
/
/
/
ꢂ
/
/
/
References
/
/
ꢂ
/
/
ꢂ
/
/
/
[1] J.P. Hogan, R.L. Banks, (Phillips Petroleum) US Patent
2,825,721, 1958.
4.11. NMR-tube synthesis of [(n-Do3TAC)AliBu2]
[B(C6F5)4] (4c)
[2] M.P. McDaniel, Adv. Catal. 33 (1985) 47.
[3] C.E. Marsden, Plast. Rubber Compos. Process. Appl. 21 (1994)
193.
[4] T.E. Nowlin, Prog. Polym. Sci. 11 (1985) 29.
[5] S.M. Augustine, J.P. Blitz, J. Catal. 161 (1996) 641.
[6] M. Ratzsch, Kunststoffe 86 (1996) 6.
¨
Do3TAC (0.022 g, 0.037 mmol), DMAB (0.03 g, 0.037
mmol), and AliBu3 as 1.0 M solution in hexane (0.083 g,
0.12 mmol) were dissolved in benzene-d6 (1 ml) to form
a colourless solution of [(n-Do3TAC)AliBu2] [B(C6F5)4]
(4c). 1H-NMR (300 MHz): d(C6D6) 3.48 (3H, d,
[7] R. Messere, A.F. Noels, P. Dournel, N. Zandona, J. Breulet,
Proceedings of Metallocenes’96, Dusseldorf, 6Á7 Marz, 1996, p.
/
¨
¨
309.
[8] K.H. Theopold, Eur. J. Inorg. Chem. (1998) (1998) 15.
[9] G.J.P. Britovsek, V.C. Gibson, D.F. Wass, Angew. Chem. Int.
Ed. Engl. 38 (1999) 428.
JHa,Hb
8.9 Hz, NÃ
(12H, d, JH,H
Hz, AlÃCH2Ã
ꢂ
/
8.9 Hz, NÃ
CHbHaÃ
6.3 Hz, CÃ
C).
/
CHaHbÃ
N), 1.76 (2H, m, CÃ
CH3), 0.07 (4H, d, JH,H
/
N), 2.88 (3H, d, JHb,Ha
CHÃC), 0.95
8.0
ꢂ
/
/
/
/
/
[10] A. Dohring, J. Gohre, P.W. Jolly, B. Kryger, J. Rust, G.P.J.
¨ ¨
ꢂ
/
/
ꢂ
/
Verhovnik, Organometallics 19 (2000) 388.
[11] J.R. Briggs, J. Chem. Soc. Chem. Commun. (1989) 674.
[12] M.E. Lashier, (Phillips Petroleum Company) EP Patent 0780353,
1995.
/
/
5. X-ray crystal structure determinations
[13] A. Carter, S.A. Cohen, N.A. Cooley, A. Murphy, J. Scutt, D.F.
Wass, J. Chem. Soc. Chem. Commun. (2002) 858.
[14] R. Emrich, O. Heinemann, P.W. Jolly, C. Kruger, G.P.J.
¨
Verhovnik, Organometallics 16 (1997) 1511.
[15] C. Pellecchia, D. Pappalardo, L. Oliva, M. Mazzeo, G.-J. Gruter,
Macromolcules 33 (2000) 2807.
Intensity data were collected at 150 K on a Nonius
Kappa CCD equipped with a low temperature device,
using graphite monochromated MoÁ
/
Ka radiation (lꢂ
/
˚
0.71070 A) and processed using the NONIUS software
[33]. For structure solution and refinement the programs
SIR-97 [34] and SHELXL-97/2 [35] were used while
illustrations were generated using ORTEP-3 [36]. Crystal
parameters and details of the data collection, solution
and refinement are summarised in Table 2. ORTEP
[16] P.J.W. Deckers, B. Hessen, J.H. Teuben, Angew. Chem. Int. Ed.
Engl. 40 (2001) 2516.
[17] C. Andes, S. Harkins, S. Murtuza, K. Oyler, A. Sen, J. Am.
Chem. Soc. 123 (2001) 7423.
[18] Z.-X. Yu, K.N. Houk, Angew. Chem. Int. Ed. 42 (2003) 808.
[19] M. Haufe, R.D. Kohn, G. Kociok-Kohn, A.C. Filippou, Inorg.
¨
¨
Chem. Commun. 1 (1998) 263.
[20] R.D. Kohn, G. Kociok-Kohn, Angew. Chem. Int. Ed. Engl. 33
¨
¨
(1994) 1877.
[21] R.D. Kohn, G. Kociok-Kohn, M. Haufe, J. Organomet. Chem.
¨
graphics of the complexes are presented in Figs. 1Á
and selected bond lengths and angles in Table 1.
Notes on the refinement: In 1a one of the ligand
groups shows disorder in a ratio of 1:1. Atoms C21Ã
C28, C21AÃC28A of this disordered group were refined
/
4,
¨
501 (1995) 303.
/
[22] M. Haufe, R.D. Kohn, R. Weimann, G. Seifert, D. Zeigan, J.
¨
Organomet. Chem. 520 (1996) 121.
/
[23] R.D. Kohn, Z. Pan, G. Kociok-Kohn, M.F. Mahon, Dalton
¨
¨
Trans. 1 (2002) 2344.
[24] R.D. Kohn, M. Haufe, G. Kociok-Kohn, S. Grimm, P. Wassersc-
isotropically. 2b and 3B crystallise with half molecule of
toluene per asymmetric unit which is disordered about a
centre of inversion. The cation in 3B is disordered in a
ratio of 2:1 and Fig. 4 shows its major component.
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 206260 for 1a, 206258 for 2a,
206259 for 2b, 206262 for 3A and 206262 for 3B. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
¨
heid, W. Keim, Angew. Chem. Int. Ed. Engl. 39 (2000) 4337.
¨
[25] R.D. Kohn, M. Haufe, S. Mihan, D. Lilge, J. Chem. Soc. Chem.
¨
Commun. (2000) 1927.
[26] M. Enders, P. Fernandez, G. Ludwig, H. Pritzkow, Organome-
tallics 20 (2001) 5005.
[27] For example in [(n-octyl3TAC)CrCl3] Cl
˚
H 2.67 and 2.76 A [24].
/
ꢀ ꢀ ꢀ
/
[28] Iodide salts: B. Morosin, Acta Crystallogr., Sect. B B30 (1974)
838; C.V. Starovskii, Yu. T. Struchkov, Zh. Strukt. Khim. 2
(1961) 161.

208
R.D. Kohn et al. / Journal of Organometallic Chemistry 683 (2003) 200Á
/208
¨
[29] E. Angelescu, C. Nicolau, Z. Simon, J. Am. Chem. Soc. 88 (1966)
3910.
[30] Zn(II): [19]; Cr(0): M.V. Baker, D.H. Brown, B.W. Skelton, A.H.
abundance; a sample of (CD3)2SO gave C, 28.2; H, 7.34; Calc.
C, 28.54, H, 14.36/2ꢂ7.18%.
/
[33] Z. Otwinowski, W. Minor, DENZO-SMN Manual, University of
Texas Southwestern Medical Center, Dallas, 1999.
White, Dalton Trans. (1999) 1483; Cu(I): R.D. Kohn, G. Seifert,
¨
[34] A. Altomare, M.C. Burla, M. Camalli, G.L. Cascarano, C.
Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, R.
Spagna, SIR-97, J. Appl. Cryst. 32 (1999) 115.
G. Kociok-Kohn, Chem. Ber. 129 (1996) 1327 and references
¨
therein.
[31] PhCH2CH23TAC is known: R. Bartnik, Rocz. Chem. 51 (1977)
49.
[35] G.M. Sheldrick, SHELXL-97-2. Program for Crystal Structure
Determination, Universitat Gottingen, Germany, 1998.
¨
¨
[32] The calculated value for %D was divided by 2 as hydrogen is
analysed with the assumption of all hydrogen at natural
[36] L.J. Farrugia, ORTEP-3 for Windows, J. Appl. Crystallogr. 30
(1997) 565.