Bulky chelating diamide complexes of zirconium: Synthesis, structure, and reactivity of d0 alkyl derivatives

Article abstract of DOI:10.1021/om9703503

The reaction of 2 equiv of LiNHAr (Ar = 2,6-ⁱPr₂C₆H₃) with 1,3-dibromopropane yields the diamine ArHN(CH₂)₃NHAr ((BAIP)H₂, 1). The reaction of (BAIP)H₂ with Zr(NMe

Full text of DOI:10.1021/om9703503

Organometallics 1997, 16, 4415-4420
4415
Bu lk y Ch ela tin g Dia m id e Com p lexes of Zir con iu m :
Syn th esis, Str u ctu r e, a n d Rea ctivity of d 0 Alk yl
Der iva tives
J ohn D. Scollard, David H. McConville,*,† and J agadese J . Vittal‡
Department of Chemistry, University of British Columbia, 2036 Main Mall,
Vancouver, British Columbia, Canada V6T 1Z1
Received April 24, 1997X
The reaction of 2 equiv of LiNHAr (Ar ) 2,6-iPr2C6H3) with 1,3-dibromopropane yields
the diamine ArHN(CH2)3NHAr ((BAIP)H2, 1). The reaction of (BAIP)H2 with Zr(NMe2)4
yields the complex (BAIP)Zr(NMe2)2 (2) and 2 equiv of NHMe2. Compound 2 reacts with 2
equiv of [Me2NH2]Cl to yield (BAIP)ZrCl2(NHMe2)2 (3) and in the presence of excess pyridine
affords the complex (BAIP)ZrCl2py2 (4). The base-free dichloride complex (BAIP)ZrCl2 (5)
can be prepared from 2 and excess ClSiMe3. The alkylation of 4 or 5 with 2 equiv of MeMgBr,
2 equiv of PhCH2MgCl, and 1 equiv of NaCp(DME) yields the alkyl derivatives (BAIP)ZrR2
(6a , R ) Me; 6b, R ) CH2Ph) and (BAIP)Zr(η5-C5H5)Cl (8), respectively. The reaction of 2
equiv of PhMe2CCH2MgCl with complex 4 yields the η2-pyridyl complex (BAIP)Zr(η2-N,C-
NC5H4)(CH2CMe2Ph) (7). An X-ray study of 7 revealed a capped tetrahedron geometry with
the pyridyl nitrogen occupying the capping position. Complex 7 is likely formed via proton
abstraction from coordinated pyridine. The catalyst system 6a /MAO polymerizes 1-hexene
to a mixture of high polymer and oligomers. Activation with {Ph3C}[B(C6F5)4] yields only
oligomers (n ) 2-7). Rapid â-hydride elimination precludes polymer formation in these
systems.
In tr od u ction
of R-olefins under the same conditions. Strong binding
of the cocatalyst to the electrophilic, low-coordinate
zirconium metal center may preclude formation of a
cationic alkyl complex, as has been observed for other
chelating diamides of Ti and Zr.8 We report here the
synthesis, structure, and reactivity of chelating diamide
complexes of zirconium, including a new, high-yield
route to base-free diamide dichloride materials. Some
of this work has appeared in a preliminary form.15
The design and synthesis of well-defined olefin po-
lymerization catalysts has developed rapidly in the last
fifteen years with the group 4 metallocene class of com-
pounds receiving considerable attention.1-3 Detailed
studies in this area have been concerned with the way
in which the stereoregularity, catalytic activity, and co-
monomer incorporation can be altered with changes to
the Cp ligand(s). For example, although the putative
complex Cp2ZrR+ will polymerize ethylene with high
activity, the homopolymerization of 1-alkenes is rela-
tively slow. In contrast, linked Cp-amide derivatives
such as [(η5-C5Me4)SiMe2(NCMe3)]TiR+ readily incor-
porate R-olefins.4,5 Given the success associated with
Cp-amide derivatives, there is growing interest in the
use of chelating diamide6-12 ligands in olefin polymer-
ization catalysis.
Resu lts
The reaction of 2 equiv of LiNHAr (generated from
H2NAr and BuLi at -78 °C, Ar ) 2,6-iPr2C6H3) with
1,3-dibromopropane affords the diamine (BAIP)H2 (1)
as a viscous yellow oil in about 47% yield (eq 1). The
We recently reported that the chelating diamide
complex [ArN(CH2)3NAr]TiMe2 (Ar ) 2,6-iPr2C6H3)
serves as a precursor for the highly active13 and living14
polymerization of R-olefins. In contrast, the analogous
zirconium compounds (e.g., [ArN(CH2)3NAr]ZrX2, X )
Me,15 Cl) show little or no activity for the polymerization
diamine is formed in a 1:1 ratio with the elimination
(6) Tinkler, S.; Deeth, R. J .; Duncalf, D. J .; McCamley, A. J . Chem.
Soc., Chem. Commun. 1996, 2623.
(7) Aoyagi, K.; Gantzel, P. K.; Kalai, K.; Tilley, T. D. Organometallics
1996, 15, 923.
(8) Warren, T. H.; Schrock, R. R.; Davis, W. M. Organometallics
1996, 15, 562.
† Author to whom correspondence may be addressed. Fax: 604-
822-2847. E-mail: mcconvil@chem.ubc.ca.
‡ Department of Chemistry, University of Western Ontario, London,
ON, Canada N6A 5B7.
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) Bochmann, M. J . Chem. Soc., Dalton Trans. 1996, 255.
(2) Brintzinger, H. H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143.
(3) Mohring, P. C.; Coville, N. J . J . Organomet. Chem. 1994, 479, 1.
(4) Canich, J . A. (Exxon) European Patent Application EP-420-436-
A1, April 4, 1991.
(5) Stevens, J . C.; Timmers, F. J .; Wilson, D. R.; Schmidt, G. F.;
Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Y. (Dow) European
Patent Application EP-416-815-A2, March 13, 1991.
(9) Horton, A. D.; de With, J .; van der Linden, A. J .; van de Weg, H.
Organometallics 1996, 15, 2672.
(10) Cloke, F. G. N.; Geldbach, T. J .; Hitchcock, P. B.; Love, J . B. J .
Organomet. Chem. 1996, 506, 343.
(11) Clark, H. C. S.; Cloke, F. G. N.; Hitchcock, P. B.; Love, J . B.;
Wainwright, A. P. J . Organomet. Chem. 1995, 501, 333.
(12) Herrmann, W. A.; Denk, M.; Albach, R. W.; Behm, J.; Herdtweck,
E. Chem. Ber. 1991, 124, 683.
(13) Scollard, J . D.; McConville, D. H.; Vittal, J . J . Macromolecules
1996, 29, 5241.
S0276-7333(97)00350-6 CCC: $14.00 © 1997 American Chemical Society

4416 Organometallics, Vol. 16, No. 20, 1997
Scollard et al.
Sch em e 1
Sch em e 2
1
preparation of a number of bis(alkyl) derivatives, large
alkyl groups (i.e., CH2SiMe3, CH2CMe2Ph) give rise to
products derived from proton abstraction from the
coordinated pyridine (vide infra). We have previously
reported17 that ClSiMe3 reacts selectively with the di-
methylamido ligands in [2,6-(ArNCH2)2NC5H3]Zr(NMe2)2.
Similarly, the BAIP ligand in 2 is inert to excess
ClSiMe3, affording the base-free dichloride (5) in excel-
lent yield (Scheme 1). 5 is highly electrophilic, irrevers-
ibly coordinating bases such as THF, pyridine, and
PMe3.
product ArHNCH2CHdCH2 (A, identified by H NMR
spectroscopy). The facile formation of A necessitates the
use of tetramethylethylenediamine (tmeda) (reactions
performed without tmeda contain about 80% A). The
diamine is easily separated from A via formation of the
ether- and water-insoluble salt [ArH2N(CH2)3NH2Ar]2+
-
{2Cl-}.
The aminolysis reaction between (BAIP)H2 and Zr-
(NMe2)4 provides 2 equiv of HNMe2 and the mixed
amide complex (BAIP)Zr(NMe2)2 (2) in excellent yield
(eq 2). A characteristic second-order pattern is observed
16
Alkyl derivatives can be prepared from 4 or 5,
depending on the bulk of the alkyl group. For example,
the bis(alkyl) complexes (BAIP)ZrR2 (6a , R ) Me; 6b,
R ) CH2Ph) and the monocyclopentadienyl derivative
(BAIP)Zr(η5-C5H5)Cl (8) are obtained cleanly from the
bis(pyridine) or the base-free dichlorides (Scheme 2).
Unlike all other complexes we have prepared bearing
the BAIP ligand, the proton NMR spectrum of 6a is
temperature dependent; in particular, the isopropyl
methyl groups appear as a broad featureless peak at
25 °C. The low-temperature-limiting spectrum (-20 °C)
shows two doublets for the isopropyl methyl groups. The
high-temperature limiting spectrum (60 °C) shows only
one doublet for the isopropyl methyls, suggesting that
the aryl groups pass through a molecular plane of
symmetry, in other words, free rotation about the
for the methylene protons (NCH2) of the coordinated
BAIP ligand in the proton NMR spectrum of complex
2. Additionally, the isopropyl methyl groups of the
arene are diastereotopic, which we interpret as a
consequence of restricted rotation about the N-Cipso
bond. The steric bulk of the ligand precludes formation
of the bis(ligand) complex (BAIP)2Zr.
Chloride derivatives were sought as precursors to
alkyl derivatives. Our initial15 attempts to prepare a
dichloride complex met with mixed success. Compound
2 reacts with 2 equiv of [Me2NH2]Cl to afford the oc-
tahedral dimethylamine adduct, (BAIP)ZrCl2(NHMe2)2
(3) in nearly quantitative yield. The BAIP ligand ap-
pears to be stable to protonolysis in contrast to what
we have observed for pyridine diamide derivatives of
zirconium-bearing ancillary dimethylamido ligands.17
However, the dimethylamine protons in 3 are attacked
by alkylating reagents; for example, the reaction of 3
and 2 equiv of MeMgBr affords the mixed amide alkyl
complex (BAIP)ZrMe(NMe2) (identified by NMR spec-
troscopy).18 Reaction of complex 2 with 2 equiv of
[Me2NH2]Cl in the presence of excess pyridine affords
a single bis(pyridine) geometrical isomer (BAIP)ZrCl2-
(py)2 (4) in 77% yield (Scheme 1). The proton and
carbon NMR spectra of 4 are consistent with a species
with C2v symmetry; however, it is not possible to
distinguish whether the chloride or pyridine ligands are
trans to the BAIP ligand. Although 4 is useful for the
q
N-Cipso bond (∆Gro t ) 13.3(5) kcal mol-1). As previ-
ously noted,15 the proton NMR spectrum of the bis-
(benzyl) complex 6b displays a high-field resonance for
the ortho protons of the benzyl groups; however, we have
been unable to observe ηn-coordination of these benzyl
groups at low temperature (to -80 °C). In addition, the
carbon NMR spectrum of 6b shows a Zr-CH2Ph reso-
1
nance at 64.2 ppm with J CH ) 124 Hz, which is normal
for η1-coordinated benzyl groups.
The 1H and 13C{1H} NMR spectra of (BAIP)Zr(η5-
C5H5)Cl are consistent with a pseudotetrahedral geom-
etry and Cs symmetry about zirconium. This gives rise
to two isopropyl methine (CHMe2) resonances and four
isopropyl methyl resonances, which is consistent with
restricted rotation about the N-Cipso bond. Monoalkyl
complexes of the type (BAIP)Zr(η5-C5H5)R (9a , R ) Me;
9b, R ) CH2Ph) are obtained cleanly from 8 and the
appropriate Grignard reagent (eq 3). The local Cs sym-
(14) Scollard, J . D.; McConville, D. H. J . Am. Chem. Soc. 1996, 118,
10008.
(15) Scollard, J . D.; McConville, D. H.; Vittal, J . J . Organometallics
1995, 14, 5478.
(16) Bradley, D. C.; Thomas, I. M. Proc. Chem. Soc., London 1959,
225.
(17) Gue´rin, F.; McConville, D. H.; Vittal, J . J . Organometallics
1996, 15, 5586.
(18) Scollard, J . D.; McConville, D. H., unpublished results.
metry is retained in these compounds.

Bulky Chelating Diamide Complexes of Zr
Organometallics, Vol. 16, No. 20, 1997 4417
Sch em e 3
Ta ble 1. Su m m a r y of Cr ysta llogr a p h ic Da ta ,
Collection P a r a m eter s, a n d Refin em en t
P a r a m eter s for Com p ou n d 7a
empirical formula
fw
C45H57N3Zr
695.13
25
0.71073 (Mo KR)
triclinic
P1h
10.146(2)
12.336(2)
16.723(2)
81.00(2)
76.99(2)
76.24(2)
1953.6(6)
2
temperature ( °C)
wavelength (Å)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
volume (Å3)
Z
F igu r e 1. (top) Chem 3D representation of 7. (bottom)
Chem 3D representation of the core of 7.
F(calc) (g/mol)
F000
1.182
740
no. of reflns collected
no. of indep reflns
no. of obs with Fo g 4σ(Fo)
no. of variable params
R1
6209
5405
2999
289
0.0951
0.2287
1.014
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 7
Bond Distances
Zr1-C1
Zr1-N1
Zr1-N3
2.268(12)
2.050(9)
2.260(10)
Zr1-C30
Zr1-N2
C30-N3
2.219(12)
2.031(9)
1.31(2)
wR2
goodness of fit (GOF)
R1 ) ∑(||Fo| - |Fc||)/∑||Fo|; wR2 ) [∑w(Fo - Fc2)2/∑wFo
] ;
a
2
4 1/2
Bond Angles
GOF ) [∑w(Fo - Fc2)2/(n - p)]1/2 (where n is the number of
reflections and p is the number of parameters refined).
2
N1-Zr1-N2
N1-Zr1-C1
N3-Zr3-C3
95.4(4)
103.9(4)
126.4(3)
C1-Zr1-C30
N2-Zr1-C1
N3-Zr1-C30
113.2(4)
104.0(4)
34.0(4)
The bis(alkyl) complexes (BAIP)ZrR2 (6c, R ) CH2-
SiMe3; 6d , R ) CH2CMe2Ph) are obtained as oils in high
yield from 5 and 2 equiv of the suitable alkylating
reagent (Scheme 3). Compounds 6c,d are exceedingly
soluble in pentane and failed to crystallize at -30 °C.
In contrast to the alkylation chemistry of the base-free
dichloride, the reaction of the bis(pyridine) complex 4
with 2 equiv of PhMe2CCH2MgCl in THF did not give
the anticipated bis(neophyl) complex, but rather the
η2-pyridyl compound (BAIP)Zr(η2-N,C-NC5H4)(CH2-
CMe2Ph) (7). Resonances attributable to an η2-pyridyl
the Zr1-C30 bond is occurring on the NMR time scale.
The Cs symmetry of 7 is maintained down to -80 °C.
We have studied15 the mechanism of formation of 7.
A deuterium labeling experiment showed that the
pyridine ortho proton is abstracted by either a coordi-
nated neophyl group (most likely) or by the neophyl
Grignard reagent. It seemed reasonable that heating
a solution of 6d in neat pyridine would lead to formation
of complex 7 and 1 equiv of tBuC6H5 (Scheme 3).
Surprisingly, no reaction occurs even after several days
at 80 °C, suggesting that (1) precoordination of pyridine
is required during the formation of 7 and (2) that it is
unlikely that the reaction proceeds via a bis(neophyl)
intermediate. On the basis of these results and the
labeling experiment, we propose that a transient
monoalkyl derivative (BAIP)ZrCl(CH2CMe2Ph)(py)2 (A)
1
moiety were also observed in the crude H NMR spec-
trum of 4 and 2 equiv of LiCH2SiMe3, but this compound
proved difficult to isolate from other byproducts. The
solid state structure of 7 was determined by X-ray
crystallography (Table 1). The molecular structure of
7 can be found in Figure 1 and relevant bond distances
and angles in Table 2. Overall the structure is best
described as a face-capped tetrahedron with the pyridyl
nitrogen occupying the capping position. The Zr1-N3-
C30 ring is structurally similar to the Zr-N-C ring in
the cationic complex [Cp2Zr(η2-picolyl)(PMe3)](BPh4).19
Each amide donor in 7 is sp2-hybridized as evidenced
by the sum of the angles about each nitrogen (N1 )
360.0° and N2 ) 359.8°). The solid state C1 symmetry
of 7 coupled with its spectroscopically observed Cs
symmetry in solution suggests that rapid rotation about
t
loses BuC6H5 slowly to yield the pyridine-stabilized
pyridyl complex (BAIP)ZrCl(η2-N,C-NC5H4)(py) (B)
(Scheme 4). Alkylation of intermediate B and loss of
pyridine affords complex 7 (free pyridine is observed in
1
the crude reaction mixture by H NMR spectroscopy).
Attempts to prepare the mononeophyl complex (BAIP)-
ZrCl(CH2CMe2Ph)(py)n (n ) 1 or 2) from 4 and 1 equiv
of ClMgCH2CMe2Ph have been unsuccessful, leading to
intractable material. We have isolated the bis(alkyl)
monopyridine complexes (BAIP)ZrR2(py) (R ) Me, CH2-

4418 Organometallics, Vol. 16, No. 20, 1997
Scollard et al.
Sch em e 4
we are unable to assign. Attempts to isolate these
species have been unsuccessful.
Borate-stabilized cations of zirconium can be gener-
ated with more reactive methide abstraction reagents;
for example, equimolar amounts of 6a and {Ph3C}-
[B(C6F5)4] oligomerize (n ) 2-7, confirmed by GC-MS)
neat 1-hexene at 23 °C with an activity of 130 g of oligo-
(1-hexene)/mmol of catalyst‚h. The MAO-activated
systems are slightly more active that the trityl borate-
activated systems, as has been observed in the analo-
gous titanium systems.23 In contrast to the MAO-
activated system above, we see no evidence of high
polymer formation in the trityl borate-activated com-
plexes. For comparison, the catalyst system (BAIP)-
TiMe2/{Ph3C}[B(C6F5)4] is an active (104,000 g of poly(1-
hexene)/mmol of catalyst‚h) living polymerization catalyst
at 68 °C (Mw ) 239 100, Mn ) 177 500; polydispersity
1.35).23 The zirconium MAO- and trityl borate-activated
systems above are dramatically effected by the presence
of toluene;13 for example, 6a /MAO and 6a /{Ph3C}-
[B(C6F5)4] are inactive in a 10% toluene in 1-hexene
mixture, likely a result of competitive binding of the
arene to the electrophilic metal center.
Ph), prepared from 6a ,b and excess pyridine;18 however,
these species do not eliminate alkane at 80 °C. In fact,
the pyridine adducts are stable for days at this temper-
ature. This suggests that A is likely six-coordinate and
that the elimination of tBuC6H5 is a result of the steric
congestion in this complex.
Given our interest in the polymerization chemistry
of group 4 diamide complexes,13,14 we undertook a study
of the 1-hexene polymerization chemistry of (BAIP)-
ZrMe2 with the cocatalysts methylaluminoxane (MAO),
B(C6F5)3,20 and {Ph3C}[B(C6F5)4].21 When activated
with MAO (500 equiv), 6a yields both high polymer (Mw
) 26 000, Mn ) 15 100; polydispersity 1.72) and oligo-
mers (n ) 2-7, confirmed by GC-MS). Activities up
to 150 g of poly(1-hexene)/mmol of catalyst‚h were
obtained in neat 1-hexene at 68 °C. For comparison,
the titanium analogue (BAIP)TiMe2 yields only high
polymer (Mw ) 81 500, Mn ) 47 000; polydispersity 1.73)
with an activity of 350 000 g of poly(1-hexene)/mmol of
catalyst‚h under the same reaction conditions.13 Based
on chain end analysis,22 the putative cationic alkyl
[(BAIP)ZrP]+ (P ) polymer) inserts 1-hexene in a 1,2
fashion followed by â-hydride elimination. The titanium
complex (BAIP)TiMe2 also inserts 1-hexene in a primary
fashion; however, these systems do not engage in
â-hydride elimination.23 It would appear that at least
two active species are generated with MAO since both
oligomers and high polymer are formed.
Con clu sion s
In summary, a high-yield route to chelating diamide
complexes of zirconium has been demonstrated. The
base-free dichloride (BAIP)ZrCl2 serves as a starting
point for the synthesis of a variety of bis(alkyl) deriva-
tives, while the pyridine-stabilized dichloride complex
(BAIP)ZrCl2(py)2 affords pyridyl complexes when the
alkylating reagent is bulky. Moderately active olefin
polymerization and oligomerization catalyst systems are
obtained when (BAIP)ZrMe2 is activated with MAO and
{Ph3C}[B(C6F5)4], respectively. Although the lack of
polymerization activity in the borane system (BAIP)-
ZrMe2/B(C6F5)3 may reflect a strong binding of the
cocatalyst to the electrophilic metal center, spectroscopic
data suggest that at least three different species are
formed when these reagents are mixed, resulting in an
ill-defined system.
Exp er im en ta l Deta ils
Gen er a l Deta ils. All experiments were performed under
an atmosphere of dry dinitrogen using standard Schlenk
techniques or in an Innovative Technology Inc. drybox. Sol-
vents were distilled from sodium/benzophenone ketyl (dimeth-
oxyethane, THF, hexanes, diethyl ether, benzene) or molten
sodium (toluene) under argon and stored over activated 4 Å
molecular sieves. ZrCl4 and 1,3-dibromopropane (Aldrich
Chemicals) were used as received. N,N,N′N′-tetramethyleth-
ylenediamine (tmeda), 2,6-diisopropylaniline, and chlorotri-
methylsilane were distilled prior to use. Zr(NMe2)4 was
synthesized following Bradley’s method.16 Proton (300 MHz)
and carbon (75.46 MHz) NMR spectra were recorded in C6D6
at approximately 22 °C on Varian Gemini-300 and Varian XL-
300 spectrometers. The proton chemical shifts were referenced
to internal C6D5H (δ ) 7.15 ppm) and the carbon resonances
to C6D6 (δ ) 128.0 ppm). Mass spectra were performed on a
Finnigan MAT Model 8230 spectrometer coupled to a Varian
3400 gas chromatograph. GPC analyses (in THF) versus
polystyrene standards were performed using a Waters GPC
equipped with Waters Styragel columns (HR 1, HR 3, HR 4).
Elemental analyses were performed by Oneida Research
Services Inc., Whitesboro, NY, and by Mr. Peter Borda at the
University of British Columbia. Ar ) 2,6-iPr2C6H3.
We have previously reported that the catalysts system
(BAIP)TiMe2/B(C6F5)3 effects the living polymerization
of R-olefins at room temperature.14 In contrast, 6a /
B(C6F5)3 is completely inactive for the polymerization
of 1-hexene at 23 °C. The following spectroscopic data
suggest that several species are formed. The 11B{1H}
NMR spectrum of equimolar amounts of 6a and B(C6F5)3
shows three boron-containing species; one that is three-
coordinate (free B(C6F5)3), and two that are four-
coordinate. In addition, the 19F{1H} NMR spectrum
shows a total of nine resonances, which is in agreement
1
with the boron NMR data. The H NMR spectrum of
6a /B(C6F5)3 shows at least three different species which
(19) J ordan, R. F.; Taylor, D. F.; Baenziger, N. C. Organometallics
1990, 9, 1546.
(20) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1964, 2, 245.
(21) Chien, J . C. W.; Tsai, W.; Rausch, M. D. J . Am. Chem. Soc.
1991, 113, 8570.
(22) Resconi, L.; Piemontesi, F.; Franciscono, G.; Abis, L.; Fiorani,
T. J . Am. Chem. Soc. 1992, 114, 1025.
(23) Scollard, J . D.; McConville, D. H.; Payne, N. C.; Vittal, J . J . J .
Mol. Catal. Chem. submitted for publication.

Bulky Chelating Diamide Complexes of Zr
Organometallics, Vol. 16, No. 20, 1997 4419
Ar HN(CH2)3NHAr ((BAIP )H2, 1). n-BuLi (2.50 M, 79.2
mL, 198 mmol) was added dropwise to a stirring THF (150
mL) solution of 2,6-diisopropylaniline (35.12 g, 198.1 mmol)
at -78 °C. The solution was warmed to 22 °C, where it was
kept for 30 min. The solution was cooled to 0 °C and tmeda
(23.0 g, 198 mmol) was added dropwise followed by 1,3-
dibromopropane (20.0 g, 99.1 mmol) dropwise. The solution
was warmed to 22 °C and stirred overnight. The solution was
poured into H2O (100 mL) and extracted with CH2Cl2 (3 × 100
mL). The organic layer was dried over anhydrous Na2SO4 and
the CH2Cl2 removed in vacuo. The resulting yellow oil was
dissolved in diethyl ether (30 mL), and concentrated HCl (20
mL) was added. The resulting salt ([ArH2N(CH2)3NH2Ar]Cl2)
was removed by filtration, washed with diethyl ether (20 mL),
and dissolved in dichloromethane. This solution was poured
into aqueous saturated NaHCO3 (100 mL). The organic layer
was separated and dried over anhydrous Na2SO4. Removal
of the solvent yielded 1 as a viscous oil (18.2 g, 46.1 mmol;
47%). 1H NMR δ 7.10 (m, 6H, Ar), 3.36 (sept, 4H, CHMe2),
3.01 (t, 4H, NCH2), 2.97 (s, 2H, NH), 1.77 (pent, 2H, NCH2CH2),
1.22 (d, 24H, CHMe2). 13C{1H} NMR δ 144.0, 143.7, 123.9,
124.4, 50.8, 32.7, 28.1, 24.5. MS (EI) m/ z 394.3342 (M+).
Calcd for C27H42N2: 394.3348.
(BAIP )Zr (NMe2)2 (2). Compound 1 (2.95 g, 7.48 mmol) and
Zr(NMe2)4 (2.00 g, 7.48 mmol) were dissolved in toluene, sealed
in a heavy-walled glass pressure vessel, and heated to 110 °C
for 3 h. The solvent was removed in vacuo and the resulting
solid extracted with pentane (3 × 100 mL) and filtered through
Celite. The volume of the filtrate was reduced to 50 mL and
cooled to -30 °C for 12 h. A white crystalline solid was
isolated by filtration and dried under vacuum (4.21 g, 7.34
mmol, 98%). 1H NMR δ 7.20 (m, 6H, Ar), 3.78 (sept, 4H,
CHMe2), 3.55 (m, 4H, NCH2), 2.64 (s, 12H, NMe2), 2.44 (m,
2H, NCH2CH2), 1.34 (d, 12H, CHMe2), 1.32 (d, 12H, CHMe2).
13C{1H} NMR δ 146.4, 145.8, 125.2, 124.1, 59.1, 41.8, 32.3,
28.3, 26.2, 25.0. Anal. Calcd for C31H52N4Zr: C, 65.09; H, 9.16;
N, 9.79. Found: C, 64.75; H, 9.19; N, 9.65.
(BAIP )Zr Cl2(NHMe2)2 (3). Compound 2 (1.92 g, 3.37
mmol) was dissolved in CH2Cl2 (25 mL) and cooled to -78 °C.
[Me2NH2]Cl (0.550 g, 6.74 mmol) was added slowly as a solid.
The resulting solution was allowed to warm to room temper-
ature and stirred overnight. The solvent was removed in vacuo
and the resulting yellow solid dissolved in toluene and filtered
through Celite. The solution volume was reduced until a
slurry formed. Hexane (60 mL) was added, and the solution
was filtered to yield a yellow crystalline solid (2.16 g, 3.35
mmol, 99%). 1H NMR δ 7.13 (m, 6H, Ar), 3.97 (sept, 4H,
CHMe2), 3.67 (m, 4H, NCH2), 2.58 (m, 2H, NCH2CH2), 2.17
(s, 2H, NH), 1.86 (s, 12H, NMe2), 1.45 (d, 12H, CHMe2), 1.29
(d, 12H, CHMe2). This compound loses NHMe2 upon isolation.
(BAIP )Zr Cl2(p y)2 (4). Compound 2 (4.80 g, 8.39 mmol)
was dissolved in a mixture of CH2Cl2 (50 mL) and pyridine (2
mL) and cooled to -78 °C. [Me2NH2]Cl (1.37 g, 16.8 mmol)
was added slowly as a solid. The resulting solution was
allowed to warm to room temperature and stirred overnight.
The solvent was removed in vacuo and the resulting yellow
solid dissolved in toluene and filtered through Celite. The
solution volume was reduced until a slurry formed. Hexanes
(60 mL) was added, and the solution was filtered to yield a
yellow crystalline solid (4.60 g, 6.45 mmol, 77%). 1H NMR δ
8.86 (dd, 4H, py), 7.11 (m, 6H, Ar), 6.52 (tt, 2H, py), 6.27 (tt,
4H, py), 4.29 (sept, 4H, CHMe2), 4.05 (m, 4H, NCH2), 2.43 (m,
2H, NCH2CH2), 1.30 (d, 12H, CHMe2), 1.15 (d, 12H, CHMe2).
13C{1H} NMR δ 151.7, 145.8, 137.6, 128.5, 125.7, 124.0, 123.2,
61.3, 33.0, 28.2, 27.8, 23.3. Carbon analyses for this compound
were low (three attempts). Anal. Calcd for C37H48Cl2N4Zr: C,
62.33; H, 7.07; N, 7.86. Found: C, 60.65; H, 7.22; N, 7.35.
(BAIP )Zr Cl2 (5). Compound 2 (0.50 g, 0.87 mmol) was
dissolved in hexanes. Excess chlorotrimethylsilane (1.0 g, 9.26
mmol) was added dropwise at room temperature and the
solution stirred overnight. After 12 h, 5 precipitated from the
solution and was collected by filtration and washed with cold
hexanes. Analytically pure 5‚1/2 n-C5H12 was obtained as a
yellow microcrystalline powder (0.43 g, 0.78 mmol, 90%) from
the recrystallization of 5 at -30 °C from a mixture of toluene/
pentane. 1H NMR δ 7.07 (m, 6H, Ar), 3.59 (sept, 4H, CHMe2),
3.51 (t, 4H, NCH2), 2.39 (m, 2H, NCH2CH2), 1.35 (d, 12H,
CHMe2), 1.23 (d, 12H, CHMe2). 13C{1H} NMR δ 146.9, 145.6,
129.8, 126.9, 62.1, 31.9, 30.9, 28.4, 27.4. Anal. Calcd for
C
27H40Cl2N2Zr‚C5H12: C, 59.97; H, 7.85; N, 4.74. Found: C,
59.84; H, 7.69; N, 4.21 (the pentane of crystallization was
confirmed by H NMR spectroscopy).
1
(BAIP )Zr Me2 (6a ). MeMgBr (2.4 M, 1.17 mL, 2.8 mmol)
was added dropwise to a stirring suspension of 4 (1.00 g, 1.40
mmol) in Et2O (50 mL) at -20 °C. The solution was warmed
to 23 °C and stirred overnight. Dimethoxyethane (2 mL) was
added and the solvent removed in vacuo. The resulting solid
was extracted with toluene and filtered through Celite. The
toluene was removed in vacuo, and the product recrystallized
from pentane at -30 °C (0.42 g, 0.82 mmol, 58%). 1H NMR δ
7.17 (m, 6H, Ar), 3.75 (sept, 4H, CHMe2), 3.47 (m, 2H, NCH2),
2.25 (m, 2H, NCH2CH2), 1.36 (m, 12H, CHMe2), 1.34 (m, 12H,
CHMe2), 0.42 (s, 6H, ZrMe2). 13C{1H} NMR δ 145.6, 143.2,
126.8, 124.5, 59.4, 39.9 (ZrMe), 29.9, 28.6, 25.8. Anal. Calcd
for C29H46N2Zr: C, 67.78; H, 9.02; N, 5.45. Found: C, 68.04;
H, 9.27; N, 5.40.
(BAIP )Zr (CH2P h )2 (6b). PhCH2MgCl (1.40 M, 2.00 mL,
2.80 mmol) was added dropwise to a stirring suspension of 4
(1.00 g, 1.40 mmol) in Et2O (50 mL) at -20 °C. The solution
was warmed to room temperature and stirred overnight. The
solvent was removed in vacuo and the solid extracted with
toluene and filtered through Celite. The solution was concen-
trated and cooled to -30 °C to yield yellow crystalline 6b (0.40
g, 0.60 mmol, 43%). 1H NMR δ 7.19 (m, 6H, Ar), 7.01 (tt, 4H,
Ph), 6.82 (tt, 2H, Ph), 6.65 (dd, 4H, Ph), 3.78 (sept, 4H,
CHMe2), 3.49 (m, 2H, NCH2), 2.31 (m, 2H, NCH2CH2), 1.95
(s, 2H, CH2Ph), 1.32 (d, 12H, CHMe2), 1.27 (d, 12H, CHMe2).
13C{1H} NMR δ 145.9, 145.1, 145.0, 130.1, 126.6, 126.5, 124.7,
122.7, 64.2 (CH2Ph, 1J CH ) 124 Hz), 58.8, 29.1, 28.4, 26.6, 25.1.
Anal. Calcd for C41H54N2Zr: C, 73.93; H, 8.17; N, 4.21.
Found: C, 73.54; H, 8.33; N, 4.27.
(BAIP )Zr (CH2SiMe3)2 (6c). Compound 5 (1.00 g, 1.40
mmol) was suspended in Et2O (50 mL). LiCH2SiMe3 (0.264
g, 2.80 mmol) was then added as a solid. The solution was
allowed to warm to room temperature and stirred overnight.
The solvent was removed in vacuo and the resulting solid
dissolved in hexanes and filtered through Celite. The hexanes
was removed in vacuo yielding 6c as a light yellow oil (0.860
g, 1.30 mmol, 93%). 1H NMR δ 7.19 (m, 6H, Ar), 3.85 (sept,
4H, CHMe2), 3.50 (m, 4H, NCH2), 2.43 (m, 2H, NCH2CH2), 1.44
(d, 6H, CHMe2), 1.35 (d, 6H, CHMe2), 0.51 (s, 2H, CH2SiMe3),
0.08 (s, 9H, SiMe3). 13C{1H} NMR δ 145.0, 144.7, 126.6, 124.7,
58.9, 58.2, 29.1, 28.2, 26.3, 25.6, 2.7.
(BAIP )Zr (CH2CMe2P h )2 (6d ). Compound 5 (1.00 g, 1.40
mmol) was suspended in THF (50 mL) and cooled to -20 °C.
(PhMe2CCH2)2Mg (0.190 M, 14.7 mL, 2.80 mmol, prepared
from PhMe2CCH2MgCl and 1,4-dioxane) was added dropwise.
The solution was allowed to warm to room temperature and
stirred overnight. The solvent was removed in vacuo and the
resulting solid dissolved in hexanes and filtered through Celite.
The hexanes was removed in vacuo yielding 6d as a yellow oil
(0.90 g, 1.2 mmol, 86%). 1H NMR δ 7.22 (m, 10H, Ar), 7.05
(m, 6H, Ar), 3.89 (sept, 4H, CHMe2), 3.47 (m, 4H, NCH2), 2.18
(m, 2H, NCH2CH2), 1.42 (d, 6H, CHMe2), 1.31 (d, 6H, CHMe2),
1.31 (s, 6H, CMe2Ph), 1.18 (s, 2H, CH2CMe2Ph). 13C{1H} NMR
δ 153.7, 146.5, 145.0, 128.5, 126.4, 125.3, 125.3, 124.8, 87.6,
58.5, 42.0, 33.9, 28.2, 26.9, 25.1.
(BAIP )Zr (η2-N,C-NC5H4)(CH2CMe2P h ) (7). PhMe2CCH2-
MgCl (0.89 M, 3.15 mL, 2.80 mmol) was added dropwise to a
stirring THF (50 mL) suspension of 4 (1.00 g, 1.40 mmol) at
-20 °C. The solution was allowed to warm to room temper-
ature and stirred overnight. The solvent was removed in vacuo
and the resulting solid extracted with pentane and filtered
through Celite. The solution was concentrated and cooled to

4420 Organometallics, Vol. 16, No. 20, 1997
Scollard et al.
-30 °C to yield colorless crystalline 7 (0.40 g, 0.58 mmol, 43%).
1H NMR δ 7.33-7.10 (m, 10H, Ar, Ph, py), 6.88 (m, 1H, Ph),
6.78 (tt, 1H, py), 6.72 (m, 2H, Ph), 6.35 (ddd, 1H, py), 4.26
(sept, 2H, CHMe2), 3.82 (m, 2H, NCH2), 3.58 (m, 2H, NCH2),
3.26 (sept, 2H, CHMe2), 2.76 (m, 1H, NCH2CH2), 2.64 (m, 1H,
NCH2CH2), 1.70 (s, 2H, CH2CMe2Ph), 1.59 (d, 6H, CHMe2),
1.47 (d, 6H, CHMe2), 1.18 (d, 6H, CHMe2), 1.17 (s, 6H, CMe2-
Ph), 0.64 (d, 6H, CHMe2). 13C{1H} NMR δ 153.9, 149.7, 145.5,
144.6, 144.5, 134.8, 129.3, 128.1, 125.3, 125.1, 125.1, 124.7,
124.0, 123.8, 68.0, 59.6, 41.0, 35.5, 31.7, 28.3, 28.1, 27.0, 26.6,
25.2, 24.1. Anal. Calcd for C42H57N3Zr: C, 72.57; H, 8.26; N,
6.04. Found: C, 72.85; H, 8.61; N, 5.95.
1.29 (d, 6H, CHMe2), 1.28 (d, 6H, CHMe2), 1.25 (d, 6H, CHMe2).
13C{1H} NMR δ 153.0, 151.6, 144.5, 142.6, 128.6, 125.9, 125.6,
124.4, 124.4, 120.8, 113.8, 69.6, 57.4, 51.1, 28.0, 27.7, 27.1, 25.9,
25.4, 24.8.
P olym er iza tion Deta ils. Compound 6a (5.0 mg, 9.7 µmol)
was mixed with 500 equiv of MAO or 1 equiv of {Ph3C}-
[B(C6F5)4] in pentane (1 mL) and added to 5.0 g of 1-hexene at
23 or 68 °C. The polymerizations were quenched after 30 (23
°C) or 10 min (68 °C) by the addition of a 1 N solution of HCl
(2 mL). The polymer/oligomer was extracted with hexanes and
dried under vacuum overnight. The samples were dissolved
in THF for GPC analysis.
(BAIP )Zr (η5-C5H5)Cl (8). NaCp(DME) (0.250 g, 1.40 mmol)
was added as a solid to a stirring toluene (50 mL) solution of
4 (1.00 g, 1.40 mmol). The solution was stirred overnight at
room temperature and then filtered through Celite. The
volume of toluene was reduced to 10 mL and hexane (50 mL)
added. Cooling to -30 °C afforded white crystals of 5c (0.770
g, 1.32 mmol, 94%). 1H NMR δ 7.12 (m, 6H, Ar), 5.93 (s, 5H,
C5H5), 3.91 (m, 1H, NCH2CH2), 3.61 (sept, 2H, CHMe2), 3.60
(sept, 2H, CHMe2), 3.60 (m, 2H, NCH2), 3.35 (m, 2H, NCH2),
2.01 (m, 1H, NCH2CH2), 1.40 (d, 6H, CHMe2), 1.32 (d, 6H,
CHMe2), 1.27 (d, 6H, CHMe2), 1.23 (d, 6H, CHMe2). 13C{1H}
NMR δ 151.1, 145.1, 142.3, 125.9, 124.6, 124.2, 114.7, 57.9,
28.0, 27.9, 27.2, 25.9, 25.6, 25.1, 25.0. Anal. Calcd for
X-r a y Cr ysta llogr a p h ic An a lysis. A suitable crystal of
7 was grown from a saturated pentane solution at -30 °C.
Crystal data may be found in Table 1. Data were collected on
a Siemens P4 diffractometer with the XSCANS software
package.24 The cell constants were obtained by centering 20
reflections (21.0 e 2θ e 24.6°). The Laue symmetry 1h was
determined by merging symmetry-equivalent positions. The
data were collected in the θ range 2.0-23° (-1ehe11,
-13eke13, -17ele18) in θ-2θ scan mode at variable scan
speeds (2-20 deg/min). Background measurements were
made at the ends of the scan range. Four standard reflections
monitored at the end of every 297 reflections collected showed
no decay of the crystal. The data processing, solution, and
refinement were done using SHELXTL-PC25 and SHELXL-
9326 programs. An empirical absorption correction was applied
to the data using the routine XEMP on the ψ scans data (µ )
0.312 mm-1). Anisotropic thermal parameters were refined
for all non-hydrogen atoms except for two phenyl ring carbon
atoms. No attempt was made to locate the hydrogen atoms.
All the bonds and angles in the isopropyl groups were
restrained to be equal using the option SADI. In the final
difference Fourier synthesis the electron density fluctuates in
C
32H45ClN2Zr: C, 65.77; H, 7.76; N, 4.79. Found: C, 66.24;
H, 7.86; N, 4.72.
(BAIP )Zr (η5-C5H5)Me (9a ). Compound 8 (1.00 g, 1.40
mmol) was suspended in Et2O (50 mL) at 23 °C. MeMgCl (3.0
M, 0.47 mL, 1.40 mmol) was added all at once. The solution
was stirred overnight at room temperature and the solvent
removed in vacuo. The resulting oil was taken up in hexane
(50 mL) and filtered. Compound 9a formed as white crystals
(0.637 g, 1.12 mmol, 80%) upon cooling to -30 °C. 1H NMR δ
7.11 (m, 6H, Ar), 5.79 (s, 5H, C5H5), 3.67 (sept, 2H, CHMe2),
3.54 (m, 2H, NCH2), 3.47 (sept, 2H, CHMe2), 3.46 (m, 1H,
NCH2CH2), 3.29 (m, 2H, NCH2), 2.07 (m, 1H, NCH2CH2), 1.42
(d, 6H, CHMe2), 1.31 (d, 6H, CHMe2), 1.23 (d, 6H, CHMe2),
1.20 (d, 6H, CHMe2), 0.36 (s, 3H, ZrMe). 13C{1H} NMR δ 151.0,
144.7, 142.9, 128.3, 125.4, 124.2, 112.8, 58.1, 28.0, 27.6, 27.3,
27.2, 25.4, 25.0, 20.8, 19.9.
the range +1.03 to -0.635 e Å-3
.
Ack n ow led gm en t . Funding from the NSERC
(Canada) in the form of a Research Grant to D.H.M. is
gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of data col-
lection and experimental details, final atomic coordinates, final
thermal parameters, bond distances and angles, calculated
hydrogen positions, selected torsional angles, and least-squares
planes and a full ORTEP diagram of 7 (10 pages). Ordering
information is given on any current masthead page.
(BAIP )Zr (η5-C5H5)(CH2P h ) (9b). Compound 8 (1.0 g, 1.4
mmol) was suspended in Et2O (50 mL). PhCH2MgCl (.69M,
2.03 mL, 1.4 mmol) was then added all at once. The solution
was stirred overnight at room temperature and the solvent
removed in vacuo. The resulting oil was dissolved in hexane
(50 mL), filtered through Celite, reduced in volume, and cooled
to -30 °C. Compound 9b formed as white crystals (0.677 g,
1.05 mmol, 75%). 1H NMR δ 7.29 (m, 2H, Ph), 7.13 (m, 1H,
Ph), 7.13 (m, 6H, Ar), 7.01 (m, 2H, Ph), 5.77 (s, 5H, C5H5),
3.55 (sept, 2H, CHMe2), 3.51 (sept, 2H, CHMe2), 3.51 (m, 2H,
NCH2), 3.38 (m, 1H, NCH2CH2), 3.28 (m, 2H, NCH2), 2.48 (s,
2H, ZrCH2Ph), 2.07 (m, 1H, NCH2CH2), 1.40 (d, 6H, CHMe2),
OM9703503
(24) XSCANS. Siemens Analytical X-Ray Instruments Inc., Madison,
WI, 1990.
(25) Sheldrick, G. M. SHELXTL-PC Software. Siemens Analytical
X-Ray Instruments Inc., Madison, WI, 1990.
(26) Sheldrick, G. M. SHELXL-93. Institute fuer Anorg. Chemie,
Goettingen, Germany, 1993.