Synthesis, structure, and reactivity of zirconium alkyl complexes bearing ancillary pyridine diamide ligands

Article abstract of DOI:10.1021/om980146v

Zirconium alkyl complexes bearing a linked pyridine diamide ligand [2,6-(RNCH₂)₂NC₅H₃]^2- (R = 2,6-diisopropylphenyl, a, (BDPP); R = 2,6-diethylphenyl, b, (BDEP); R = 2,6-dimethylphenyl, c, (BDMP)) have been synthesized. The bis(benzyl) derivatives (2a-c) undergo an η¹-, η²-benzyl flip, which is likely a result of the electrophilic nature of the zirconium metal center. The bis(trimethylsilylmethyl) derivative (BDPP)Zr(CH₂SiMe₃)₂ (3a) is also fluxional; however, this behavior is attributable to the steric crowding in this complex. In contrast, the analogous compounds bearing the less bulky BDEP and BDMP ligands do not show fluxional behavior. The butadiene complexes (BDPP)Zr(C₄He) (5a) (determined by X-ray crystallography), (BDEP)Zr(C₄H₆) (5b), and (BDMP)Zr(C₄H₆) (5c) adopt an s-cis bent metallacyclo-3-pentene structure with significant πr-donation from the double bond. Consistent with the rigid nature of these complexes, no insertion chemistry is observed below 90°C. Alkenes and alkynes react (>90°C) via insertion into the Zr-C σ-bond to give σ,π-allyl products.

Full text of DOI:10.1021/om980146v

5172
Organometallics 1998, 17, 5172-5177
Syn th esis, Str u ctu r e, a n d Rea ctivity of Zir con iu m Alk yl
Com p lexes Bea r in g An cilla r y P yr id in e Dia m id e Liga n d s
Fre´de´ric Gue´rin,† David H. McConville,*,† J agadese J . Vittal,‡ and
Glen A. P. Yap§
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver,
British Columbia, Canada V6T 1Z1; Department of Chemistry, University of Western Ontario,
London, Ontario, Canada N6A 5B7; and Windsor Molecular Structure Center, Department of
Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada, N9B 3P4
Received March 2, 1998; Revised Manuscript Received September 1, 1998
Zirconium alkyl complexes bearing a linked pyridine diamide ligand [2,6-(RNCH2)2NC5H3]2-
(R ) 2,6-diisopropylphenyl, a , (BDPP); R ) 2,6-diethylphenyl, b, (BDEP); R ) 2,6-
dimethylphenyl, c, (BDMP)) have been synthesized. The bis(benzyl) derivatives (2a -c)
undergo an η1-, η2-benzyl flip, which is likely a result of the electrophilic nature of the
zirconium metal center. The bis(trimethylsilylmethyl) derivative (BDPP)Zr(CH2SiMe3)2 (3a )
is also fluxional; however, this behavior is attributable to the steric crowding in this complex.
In contrast, the analogous compounds bearing the less bulky BDEP and BDMP ligands do
not show fluxional behavior. The butadiene complexes (BDPP)Zr(C4H6) (5a ) (determined
by X-ray crystallography), (BDEP)Zr(C4H6) (5b), and (BDMP)Zr(C4H6) (5c) adopt an s-cis
bent metallacyclo-3-pentene structure with significant π-donation from the double bond.
Consistent with the rigid nature of these complexes, no insertion chemistry is observed below
90 °C. Alkenes and alkynes react (>90 °C) via insertion into the Zr-C σ-bond to give σ,π-
allyl products.
In tr od u ction
complexes supported by chelating diamide ligands. We
have previously8 shown that the pyridine diamide
zirconium fragment [2,6-(RNCH2)2NC5H3]Zr (A, R )
aryl) can be viewed as an electron-deficient analogue
of Cp2Zr (B).
The organometallic chemistry of zirconium in the +4
oxidation state has been dominated by complexes sup-
ported by cyclopentadienyl ligands.1,2 Within this class
of compounds, cationic metallocene derivatives3,4 of the
type [Cp2ZrR]+ exhibit high activity for the polymeri-
zation of ethylene and R-olefins.5-7 The bent Cp2Zr
framework restricts coordination of olefins to a site cis
to the Zr-R bond, while the formally 14-electron count
results in a highly electrophilic metal center. Studies
in this area have been concerned with the way in which
the stereoregularity, catalytic activity, and comonomer
incorporation can be altered with changes to the Cp
ligand(s). In an effort to develop new families of
catalysts with similar structural and/or electronic fea-
tures, we are exploring the organometallic and poly-
merization chemistry of zirconium8,9 and titanium10,11
In addition, the sterics of the pyridine diamide ligand
can be altered readily by varying the size of the
substituents at nitrogen. Herein, we report the syn-
thesis, reactivity, and fluxional behavior of a number
of mono and bis(alkyl) derivatives of zirconium bearing
pyridine diamide ligands of varying steric bulk. The
similarities and differences between these compounds
and their Cp2Zr congeners will be presented.
† University of British Columbia.
‡ University of Western Ontario.
§ University of Windsor.
(1) J ubb, J .; Song, J .; Richeson, D.; Gambarotta, S. In Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson,
G., Ed.; Elsevier Science Ltd.: New York, 1995; Vol. 4.
(2) Cardin, D. J .; Lappert, M. F.; Raston, C. L. Chemistry of Organo-
Zirconium and -Hafnium Compounds; Ellis Horwood Ltd.: Chichester,
U.K., 1986.
(3) Eisch, J . J .; Piotrowski, A. M.; Brownstein, S. K.; Gabe, E. J .;
Lee, F. L. J . Am. Chem. Soc. 1985, 107, 7219.
(4) J ordan, R. F.; Dasher, W. E.; Echols, S. F. J . Am. Chem. Soc.
1986, 108, 1718.
(5) Bochmann, M. J . Chem. Soc., Dalton Trans. 1996, 255.
(6) Brintzinger, H. H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143.
(7) Mohring, P. C.; Coville, N. J . J . Organomet. Chem. 1994, 479, 1.
(8) Gue´rin, F.; McConville, D. H.; Vittal, J . J . Organometallics 1996,
15, 5586.
Resu lts a n d Discu ssion
We have reported8 the synthesis of the zirconium
pyridine diamide complexes [2,6-(RNCH2)2NC5H3]ZrCl2
(1a , R ) 2,6-iPr2C6H3, (BDPP)ZrCl2; 1b, R ) 2,6-
Et2C6H3, (BDEP)ZrCl2; 1c, R ) 2,6-Me2C6H3, (BDMP)-
ZrCl2). The reaction of the dichlorides 1a -c with 2
equiv of BrMgCH2Ph in ether at 23 °C affords the bis-
(benzyl) derivatives 2a -c in good yield (Scheme 1).
(10) (a) Scollard, J . D.; McConville, D. H. J . Am. Chem. Soc. 1996,
118, 10008. (b) Scollard, J . D.; McConville, D. H.; Vittal, J . J .
Macromolecules 1996, 29, 5241.
(9) Scollard, J . D.; McConville, D. H.; Vittal, J . J . Organometallics
1995, 14, 5478.
(11) Gue´rin, F.; McConville, D. H.; Payne, N. C. Organometallics
1996, 15, 5085.
10.1021/om980146v CCC: $15.00 © 1998 American Chemical Society
Publication on Web 10/13/1998

Zirconium Alkyl Complexes
Organometallics, Vol. 17, No. 23, 1998 5173
Sch em e 1
F igu r e 1. The ligand methylene and methine region of
the variable-temperature NMR spectra of compound 2a .
Compounds 2a and 2c are isolated as crystalline
solids from CH2Cl2, while complex 2b, which bears ethyl
groups in the 2,6-position of the aryl substituents, is
isolated as an oily solid due to its high solubility in
pentane. The proton NMR spectrum of compound 2a
is broad and featureless at room temperature (Figure
1). The low-temperature (-40 °C) limiting spectrum of
2a displays resonances for a species with Cs symmetry;
in particular, two isopropyl methine resonances (CHMe2)
and an AB quartet pattern (NCH2) are observed for the
BDPP ligand, indicating asymmetry about the ligand
N3 plane. In addition, a high-field resonance (5.90 ppm)
is observed for the ortho protons of a single benzyl
group. These low-temperature proton NMR features
are consistent with an η1-, η2-benzyl formulation12 which
is supported by the solid-state structure13 of 2a (Figure
2). The above resonances coalesce at 10 °C, yielding a
F igu r e 2. Chem 3D representation of the molecular
structure of compound 2a (the isopropyl methyl groups
have been removed for clarity). Only connectivity could be
established.
Sch em e 2
1
In contrast to complex 2a , the room-temperature H
NMR spectra of compounds 2b and 2c display sharp
resonances for species with C2v symmetry. However,
upon cooling, both compounds show resonances con-
sistent with both η1- and η2-benzyl ligands (2b, Tc )
-20 °C, ∆Gq ) 11.5(5) kcal mol-1; 2c, Tc ) -30 °C, ∆Gq
) 11.2(5) kcal mol-1). Interestingly, the low-tempera-
ture (-80 °C) limiting spectrum of compound 2c dis-
plays resonances for inequivalent aryl methyl groups,
consistent with restricted rotation of the N-Cipso bond
at this temperature (similarly, 2a displays inequivalent
isopropyl methyl groups and 2b shows diastereotopic
methylene protons in the aryl ethyl groups). The room-
temperature proton NMR spectrum14 of the metallocene
bis(benzyl) derivative Cp2Zr(CH2Ph)2 shows no evidence
of η2-benzyl ligands. In contrast, the structurally
barrier to “benzyl flipping” of ∆Gq ) 13.5(5) kcal mol-1
.
At higher temperatures (>40 °C) the benzyl ligands
exchange rapidly, leading to a species with C2v sym-
metry (Scheme 2).
(12) Bei, X.; Swenson, D. C.; J ordan, R. F. Organometallics 1997,
16, 3282.
(13) X-ray data for 2a were collected at 25 °C on a Siemens P4
diffractometer using graphite-monochromated Mo KR radiation. A total
of 3654 reflections were collected in the θ range 1.88-21.0° with
significant crystal decay (26.3%), resulting in a low data-to-parameter
ratio (6.3:1). Therefore only the connectivity has been established.
Crystal data: C45H55N3Zr; MW ) 849.29; monoclinic; space group P21/
n; a ) 12.535(11) Å, b ) 21.683(21) Å, c ) 14.543(18) Å, â ) 90.28(1)°;
V ) 3952(7) Å3; Z ) 4; Fcalcd ) 1.223 g cm-3. In the final least-squares
refinement cycles on F, the model converged at R ) 0.0972, wR )
0.1077, and GoF ) 1.62 for 989 observations with Fo ) 4σ(Fo) and 156
parameters (see Supporting Information).
(14) Fachinetti, G.; Floriani, C. J . Chem. Soc., Chem. Commun.
1972, 654.

5174 Organometallics, Vol. 17, No. 23, 1998
Gue´rin et al.
Ta ble 1. Selected Cr ysta llogr a p h ic Da ta for
Com p ou n d 5a a
Sch em e 3
empirical formula
fw
C35H47N3Zr‚0.35Et2O
616.49
cryst dimens (mm)
cryst syst
0.20 × 0.10 × 0.10
tetragonal
space group
a ) b (Å)
c (Å)
I-42d
16.155(3)
26.847(3)
R ) â ) γ (deg)
90
7007(2)
V (Å3)
Z
8
F (calc) (g/mol)
collection temp (K)
F000
1.169
298(2)
2612
characterized cationic benzyl derivative [Cp2Zr(η2-
CH2Ph)(NtCMe)]+{BPh4}- and the spectroscopically
identified base-free complex [(η5-C5H4Me)2Zr(η2-CH2Ph)]+-
{BPh4}- 15 clearly show the presence of an η2-benzyl
moiety.
Mo KR
graphite (monochromated)
2019 (R(int) ) 0.2999)
244
0.0765
0.1635
1.029
total no. of unique reflns
no. of variable params
R1
The dichlorides 1a -c react with 2 equiv of LiCH2-
SiMe3 in ether to afford the bis(trimethylsilylmethyl)
derivatives in excellent isolated yield (Scheme 1). Com-
pounds 3a -c are isolated as bright yellow crystalline
solids from hexanes. The proton NMR spectra of
compounds 3b and 3c show resonances for species with
C2v symmetry at temperatures between -80 and +80
wR2
goodness of fit (GoF)
R1 ) ∑(||Fo| - |Fc||)/∑|Fo|; wR2 ) [∑w(Fo - Fc2)2/∑wFo
]
;
a
2
4 1/2
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
5a -c in excellent isolated yield (Scheme 1). The proton
NMR spectra of compounds 5a -c display characteristic
resonances for species with Cs symmetry; however, the
mirror symmetry is in the plane of the meridionally
coordinated pyridine diamide ligand; the 1H NMR
spectrum of the diene derivative 5c shows two ligand
methylene (NCH2) signals which are not coupled. The
diene fragment in all three complexes adopts an s-cis
bent metallacyclo-3-pentene structure18,19 with signifi-
cant π-donation from the cyclopentene double bond; for
example, the proton NMR spectrum of compound 5c
displays signals at 4.98, 3.42, and 0.17 ppm for Hm, Ha,
and Hs, respectively (C).
1
°C. In contrast, the room-temperature H NMR spec-
trum of complex 3a , which bears isopropyl groups in
the 2,6-position of the aryl substituents, is broad and
featureless. The high-temperature (+70 °C) limiting
spectrum shows resonances for the expected C2v-sym-
metric product, including a Zr-CH2SiMe3 signal at 0.65
ppm. The low-temperature limiting spectrum displays
sharp signals for a species with Cs symmetry; for
example, an AB quartet at 4.80 ppm and two isopropyl
methines at 4.26 and 3.36 ppm result from asymmetry
about the ligand N3 plane. The absence of fluxionality
in compounds 3b and 3c suggests that the origin of this
behavior in compound 3a is steric and not electronic.
Hence, we propose that the bulk of the isopropyl
substituents in compound 3a prevents both trimethyl-
silyl groups from simultaneously residing adjacent to
these substituents, in other words, to point outward
(Scheme 3).
The above resonances coalesce at 20 °C, yielding a
barrier to “Zr-C bond rotation” of ∆Gq ) 13.4(5) kcal
The Cs symmetry of compound 5a is retained to +80
°C, and we see no evidence of syn/anti proton exchange,
consistent with rigid coordination of the diene fragment
to the highly electrophilic zirconium center. The zir-
conocene derivative Cp2Zr(η4-C4H6) exists in two iso-
meric forms, having the butadiene coordinated in either
the s-cis or s-trans configuration.19 The s-trans complex
is considerably more reactive than the s-cis isomer (vide
infra).20
The solid-state structure of 5a was determined by
X-ray crystallography (Table 1). The molecular struc-
ture of complex 5a can be found in Figure 3 and relevant
bond distances and angles in Table 2. The amide- and
pyridine-zirconium bond distances are statistically the
same as those found in (BDEP)ZrMe2.8 The long-
short-long bond alternation in the diene fragment
coupled with the short Zr-C(17) and long Zr-C(18)
bonds confirms the s-cis bent metallacyclo-3-pentene
mol-1
.
In the solid-state structure of Cp2Zr(CH2-
SiMe3)2,16 the trimethylsilylmethyl groups are arranged
in the least sterically hindered position, that is, with
both trimethylsilyl moieties directed outward.
Compounds 1a -c react cleanly with NaCp‚DME
(DME ) dimethoxyethane) in ether at -20 °C to give
the white crystalline mono(cyclopentadienyl) derivatives
4a -c in good yield (Scheme 1). All three compounds
display proton and carbon resonances consistent with
molecular Cs symmetry. It has been proposed17 that the
tris(methylcyclopentadienyl) derivative (C5H4Me)3ZrCl
contains two η5-coordinated MeCp rings and one η1-
coordinated ring. We see no evidence of an η1-Cp ligand
in the low-temperature proton NMR spectrum of com-
pound 4a .
The dichlorides 1a -c react with Mg(C4H6)‚2THF in
ether at -20 °C to give the zirconium diene derivatives
(15) J ordan, R. F.; LaPointe, R. E.; Bajgur, C. S.; Echols, S. F.;
Willett, R. J . Am. Chem. Soc. 1987, 109, 4111.
(16) J effery, J .; Lappert, M. F.; Luong-Thi, N. T.; Webb, M.; Atwood,
J . L.; Hunter, W. E. J . Chem. Soc., Dalton Trans. 1981, 1593.
(17) Etievant, P.; Gautheron, B.; Tainturier, G. Bull. Soc., Chim.
Fr. 1978, II, 292.
(18) Yasuda, H.; Tatsumi, K.; Nakamura, A. Acc. Chem. Res. 1985,
18, 120.
(19) Erker, G.; Kru¨ger, C.; Mu¨ller, G. Adv. Organomet. Chem. 1985,
24, 1.
(20) Erker, G.; Engel, K.; Dorf, U.; Atwood, J . L.; Hunter, W. E.
Angew. Chem., Int. Ed. Engl. 1982, 21, 914.

Zirconium Alkyl Complexes
Organometallics, Vol. 17, No. 23, 1998 5175
Sch em e 4
F igu r e 3. Chem 3D representation of the molecular
structure of compound 5a .
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 5a
isopropyl methine, and eight isopropyl methyl reso-
nances. We see no evidence for syn/anti proton ex-
change in the allyl group to 80 °C, suggesting that this
moiety is firmly coordinated to the electrophilic zirco-
nium center. In an analogous fashion, Cp2Zr(η4-iso-
prene) reacts with 2-butyne to give a σ,π-allyl deriva-
tive.23 The reaction of compound 5a with HCtCSiMe3
affords a single isomer (7a ) derived from 2,1-insertion
of the acetylenic unit into the Zr-C bond. The substi-
tution pattern of complex 7a was established on the
basis of 1H NMR spectroscopy, 1H COSY, and NOE
experiments. For example, irradiation of the low-field
vinylic resonance (δ 8.02 ppm) results in a strong
enhancement of the metallacycle CdCH-CH2 protons.
The reaction of complex 5a with excess 1-hexene also
affords a 2,1-insertion type product. The presence of
two AB quartets for the ligand methylene protons
(NCH2) is consistent with a complex with C1 symmetry.
The 2,1-insertion of the olefin was confirmed by a
Bond Distances
Zr-N(1)
Zr-N(2)
Zr-N(2A)
Zr-C(17)
Zr-C(20)
2.307 (13)
2.111 (8)
2.111 (8)
2.36 (2)
Zr-C(18)
2.47 (2)
2.47 (2)
1.56 (3)
1.36 (3)
1.55 (3)
Zr-C(19)
C(17)-C(18)
C(18)-C(19)
C(19)-C(20)
2.33 (2)
Bond Angles
N(2)-Zr-N(2A)
N(1)-Zr-C(17)
N(1)-Zr-C(20)
Zr-C(17)-C(18)
140.0 (4)
133.3 (6)
141.4 (7)
37.7 (7)
Zr-C(20)-C(19)
C(17)-C(18)-C(19)
C(20)-C(19)-C(18)
N(2)-Zr-N(1)
37.5 (7)
126 (2)
121 (2)
70.0 (2)
formulation. Overlap of the 5b2 and 13a1 frontier
molecular orbitals8 of the (BDPP)Zr fragment with the
sp3-hybrids on carbons C(17) and C(20) accounts for the
σ-bonds between Zr and these carbons.21 Presumably,
the π-donation from carbons C(18) and C(19) is mainly
into the empty 10b1 orbital on zirconium.
1
combination of H,13C COSY, and 13C-APT and experi-
ments; in particular, an inverted peak is observed for
the carbon attached to the zirconium (42.49 ppm),
characteristic of a tertiary carbon. In contrast, most
1-alkenes (1-butene, 1-octene, etc.) react with Cp2Zr-
(diene) in a 1,2 fashion.22-24
Con clu sion s
A series of alkyl derivatives stabilized by a linked
pyridine diamide ligand have been prepared. The bis-
(benzyl) derivatives undergo an η1-, η2-benzyl flip, which
is likely a result of the electrophilic nature of the
zirconium metal center. The bis(trimethylsilylmethyl)
derivative (BDPP)Zr(CH2SiMe3)2 is also fluxional; how-
ever, this behavior is attributable to the steric crowding
in this complex. The butadiene complexes 5a -c adopt
an s-cis bent metallacyclo-3-pentene structure with
significant π-donation from the double bond. Consistent
with the rigid nature of these complexes, no insertion
chemistry is observed below 90 °C. Alkenes and alkynes
react (>90 °C) via insertion into the Zr-C σ-bond to give
σ,π-allyl products. The fluxionality and reactivity of the
pyridine diamide derivatives detailed herein are con-
sistent with the electron deficiency of these compounds
as compared to their metallocene analogues.
The diene complex 5a does not react with unsaturated
substrates over several days at 23 °C; however, upon
heating to 90 °C in benzene products derived from
insertion into the Zr-C σ-bond are observed (Scheme
4).
The σ,π-allyl formulation for compounds 6a , 7a , and
8a is based on characteristic proton22,23 and carbon24,25
resonances for the Zr-allyl functional group and the
1
observed C1 symmetry for all three complexes. The H
NMR spectrum for compound 6a displays two AB
quartets for the ligand methylene (NCH2) protons, four
(21) Calculations were performed on an appropriate model using
CAChe Scientific Inc. software.
(22) Yasuda, H.; Kajihara, Y.; Nagasuna, K.; Mashima, K.; Naka-
mura, A. Chem. Lett. 1980, 719.
(23) Kai, Y.; Kanehisa, N.; Miki, K.; Kasai, N.; Mashima, K.;
Nagasuna, K.; Yasuda, H.; Nakamura, A. Chem. Lett. 1982, 1979.
(24) Erker, G.; Berg, K.; Kru¨ger, C.; Mu¨ler, G.; Angermund, K.;
Benn, R.; Schroth, G. Angew. Chem., Int. Ed. Engl. 1984, 23, 455.
(25) Temme, B.; Karl, J .; Erker, G. Chem. Eur. J . 1996, 2, 919.
Exp er im en ta l Section
Gen er a l Deta ils. All experiments were performed under
a dry dinitrogen atmosphere using standard Schlenk tech-

5176 Organometallics, Vol. 17, No. 23, 1998
Gue´rin et al.
niques or in an Innovative Technology Inc. glovebox. Solvents
were distilled from sodium/benzophenone ketyl (DME, THF,
hexanes, diethyl ether, and benzene) or molten sodium (tolu-
ene) under argon and stored over activated 4 Å molecular
sieves. Zirconium(IV) chloride was purchased from Alfa and
used as received. The 4-octyne, trimethylsilylacetylene, and
1-hexene were purchased from Aldrich and distilled prior to
use. The compounds (BDPP)ZrCl2 (1a ), (BDEP)ZrCl2 (1b), and
(BDMP)ZrCl2 (1c) were synthesized by literature procedures.8
Unless otherwise specified, proton (300 MHz) and carbon
(75.46 MHz) NMR spectra were recorded in C6D6 at ap-
proximately 22 °C on a Varian Gemini-300 or 300-XL spec-
trometer. The proton chemical shifts were referenced to
internal C6D5H (δ ) 7.15 ppm) and the carbon resonances to
C6D6 (δ ) 128.0 ppm). Elemental analyses were performed
using sealed tin cups on a Fisons Instruments model 1108
elemental analyzer by Mr. Peter Borda of this department or
by Oneida Research Services Inc., Whitesboro, NY.
and dried under vacuum (0.109 g, 0.156 mmol, 88%). 1H
NMR: δ 7.24 (b, 6H, Ar), 6.86 (t, 1H, py), 6.40 (d, 2H, py), 5.0
(br, 4H, NCH2), 1.52 and 1.28 (br, 12H each, CHMe2), -0.13
(br, 18H, SiMe3). 1H NMR (toluene-d8, 70 °C): δ 7.20-7.25
(m, 6H, Ar), 6.98 (t, 1H, py), 6.54 (d, 2H, py), 4.96 (s, 4H,
NCH2), 3.91 (br, 4H, CHMe2), 1.49 and 1.26 (d, 12H each,
CHMe2), 0.65 (s, 4H, ZrCH2Si), -0.18 (s, 18H, SiMe3). 13C{1H}
NMR: δ 146.13, 127.38, 124.68, 117.32, 67.78, 28.18, 27.46,
24.25, 2.82. Anal. Calcd for C39H63N3Si2Zr: C, 64.94; H, 8.80;
N, 5.83. Found: C, 64.94; H, 8.77; N, 5.95.
(BDEP )Zr (CH2SiMe3)2 (3b). The preparation of compound
3b is identical to that for complex 3a . Compound 1b (0.100
g, 0.178 mmol) and Me3SiCH2Li (0.037 g, 0.393 mmol) gave
yellow crystalline 3b (0.109 g, 0.156 mmol, 88%). 1H NMR:
δ 7.15-7.25 (m, 6H, Ar), 6.88 (t, 1H, py), 6.43 (d, 2H, py), 4.77
(s, 4H, NCH2), 3.05 (m, 8H, CH2Me), 1.33 (t, 12H, CH2Me),
0.54 (s, 4H, ZrCH2Si), -0.13 (s, 18H, SiMe3). 13C{1H} NMR:
δ 163.33, 149.42, 141.39, 138.43, 126.75, 125.84, 117.58, 66.60,
58.79, 24.57, 15.75, 2.99.
(BDMP )Zr (CH2SiMe3)2 (3c). The preparation of com-
pound 3c is identical to that for complex 3a . Compound 1c
(0.100 g, 0.198 mmol) and Me3SiCH2Li (0.041 g, 0.435 mmol)
gave yellow crystalline 3c (0.103 g, 0.169 mmol, 85%). 1H
NMR: δ 7.15 (d, 4H, Ar), 7.03 (m, 2H, Ar), 6.91 (t, 1H, py),
6.47 (d, 2H, py), 4.64 (s, 4H, NCH2), 2.48 (s, 12H, Me), 0.61 (s,
4H, ZrCH2Si), -0.13 (s, 18H, SiMe3). 13C{1H} NMR: δ 163.49,
150.53, 138.32, 135.85, 129.34, 125.39, 117.53, 64.94, 58.43,
19.54, 3.00.
(BDP P )Zr (CH2P h )2 (2a ). To a diethyl ether (25 mL)
suspension of compound 1a (0.100 g, 0.162 mmol) was added
2.2 equiv of PhCH2MgBr (0.32 mL, 1.13 M, 0.36 mmol) at 23
°C. The suspension was stirred for 12 h. The solvent was
removed in vacuo. The resulting solid was extracted with
toluene (3 × 10 mL) and filtered through Celite to give a
bright-yellow solution. The solvent was removed in vacuo, and
the solid was dissolved in a minimum amount of dichloro-
methane and cooled to -30 °C for 12 h. Yellow crystalline 2a
was isolated by filtration and dried under vacuum (0.093 g,
0.128 mmol, 79%). 1H NMR (toluene-d8, 23 °C): δ 6.90-7.30
(m, Ar and CH2Ph), 6.82 (t, 1H, py), 6.35 (d, 2H, py), 4.82 (br,
4H, NCH2), 3.85 (br, 4H, CHMe2), 1.92 (br, 4H, CH2Ph), 1.45
(br, 12H, CHMe2), 1.21 (d, 12H, CHMe2). 1H NMR (toluene-
d8, -40 °C): δ 6.90-7.30 (m, 6H, Ar and CH2Ph), 6.82 (m,
4H, m Ph), 6.75 (t, 1H, py), 6.51 (m, 2H, p Ph), 6.23 (d, 2H,
(BDP P )Zr Cp Cl (4a ). To a diethyl ether (25 mL) suspen-
sion of compound 1a (0.100 g, 0.162 mmol) was added 1.3 equiv
of NaCp‚DME (0.038, 0.213 mmol) at -20 °C. The suspension
was stirred for 12 h. The solvent was removed in vacuo. The
resulting solid was extracted with toluene (3 × 10 mL) and
filtered through Celite to give a colorless solution. The solvent
was removed in vacuo, and the solid was dissolved in a
minimum amount of diethyl ether and cooled to -30 °C for 12
h. White crystalline 4a was isolated by filtration and dried
under vacuum (0.093 g, 0.144 mmol, 89%). 1H NMR: δ 7.10-
7.25 (m, 6H, Ar), 6.75 (t, 1H, py), 6.33 (d, 2H, py), 6.04 (s, 5H,
2
py), 5.90 (d, 2H, o Ph), 4.81 (AB quartet, J HH ) 20.2 Hz, 4H,
NCH2), 4.03 (sept, 2H, CHMe2), 3.71 (sept, 2H, CHMe2), 2.10
(s, 2H, CH2Ph), 1.64 (s, 2H, CH2Ph), 1.51 (d, 6H, CHMe2), 1.40
(d, 6H, CHMe2), 1.38 (d, 6H, CHMe2),1.08 (d, 6H, CHMe2).
Partial 13C{1H} NMR (toluene-d8, 23 °C): δ 68.87 (NCH2).
Anal. Calcd for C45H55N3Zr‚1/4CH2Cl2: C, 72.43; H, 7.45; N,
5.60. Found: C, 72.65; H, 7.62; N, 5.59.
2
Cp), 4.78 (AB quartet, J HH ) 20.2 Hz, 4H, NCH2), 3.90 and
3.23 (sept, 2H each, CHMe2), 1.53, 1.35, 1.32 and 0.92 (d, 6H
each, CHMe2). 13C{1H} NMR: δ 161.50, 157.38, 145.12,
142.52, 137.61, 125.24, 124.77, 123.81, 116.56, 116.26 (C5H5),
68.30, 28.70, 27.82, 27.67, 26.68, 24.04, 23.54. Anal. Calcd
for C36H46ClN3Zr: C, 66.78; H, 7.16; N, 6.49. Found: C, 66.98;
H, 7.24; N, 6.35.
(BDEP )Zr (CH2P h )2 (2b). The preparation of compound
2b is identical to that for complex 2a . Compound 1b (0.300
g, 0.534 mmol) and PhCH2MgBr (1.42 mL, 1.13M, 1.60 mmol)
gave a yellow oily solid 2b. The crude yield of 2b is >90%;
however, the compound is exceedingly soluble, which precludes
its isolation. 1H NMR: δ 6.5-7.4 (m, 15H, py, Ar and Ph),
6.35 (d, 4H, Ph), 4.55 (s, 4H, NCH2), 2.89 (q, 8H, CH2Me), 1.61
(s, 4H, ZrCH2Ph), 1.26 (t, 12H, CH2Me). 13C{1H} NMR: δ
162.74, 149.81, 141.59, 137.76, 129.59, 126.83, 126.18, 125.79,
122.01, 117.17, 65.69, 60.95, 24.66, 15.15.
(BDMP )Zr (CH2P h )2 (2c). The preparation of compound
2c is identical to that for complex 2a . Compound 1c (0.075 g,
0.148 mmol) and PhCH2MgBr (0.29 mL, 1.13 M, 0.33 mmol)
gave yellow crystalline 2c (0.089 g, 0.144 mmol, 97%). 1H
NMR: δ 7.08 (m, 4H, Ar), 6.98 (m, 2H, Ar), 6.87 (m, 4H, Ph),
6.84 (t, 1H, py), 6.67 (m, 2H, Ph), 6.36 (m, 4H, Ph), 6.34 (d,
2H, py), 4.42 (s, 4H, NCH2), 2.37 (s, 12H, Me), 1.66 (s, 4H,
ZrCH2Ph). 13C{1H} NMR: δ 162.85, 150.76, 137.59, 136.25,
129.64, 126.69, 125.40, 121.94, 117.13, 64.12, 60.62, 60.57,
19.62. Anal. Calcd for C37H39N3Zr: C, 72.03; H, 6.37; N, 6.81.
Found: C, 71.89; H, 6.65; N, 6.82.
(BDP P )Zr (CH2SiMe3)2 (3a ). To a diethyl ether (25 mL)
suspension of compound 1a (0.100 g, 0.178 mmol) was added
2.2 equiv of Me3SiCH2Li (0.037 g, 0.393 mmol) at -20 °C. The
suspension was stirred for 12 h. The solvent was removed in
vacuo. The resulting solid was extracted with toluene (3 ×
10 mL) and filtered through Celite to give a bright-yellow
solution. The solvent was removed in vacuo, and the solid was
dissolved in a minimum amount of hexanes and cooled to -30
°C for 12 h. Yellow crystalline 3a was isolated by filtration
(BDEP )Zr Cp Cl (4b). The preparation of compound 4b is
identical to that for complex 4a . Compound 1b (0.100 g, 0.178
mmol) and NaCp‚DME (0.040 g, 0.224 mmol) gave white
crystalline 4b (0.091 g, 0.154 mmol, 87%). 1H NMR: δ 7.00-
7.25 (m, 6H, Ar), 6.79 (t, 1H, py), 6.37 (d, 2H, py), 5.89 (s, 5H,
2
Cp), 4.51 (AB quartet, J HH ) 20.6 Hz, 4H, NCH2), 3.05 and
2.49 (m, 4H each, CH2Me), 1.39 and 1.08 (t, 6H each, CH2Me).
13C{1H} NMR: δ 161.48, 159.444, 140.21, 137.62, 137.50,
126.88, 126.11, 124.74, 116.85, 116.38 (C5H5), 67.14, 24.59,
24.05, 15.88, 14.84.
(BDMP )Zr Cp Cl (4c). The preparation of compound 4c is
identical to that for complex 4a . Compound 1c (0.100 g, 0.98
mmol) and NaCp‚DME (0.045 g, 0.253 mmol) gave white
crystalline 4c (0.093 g, 0.174 mmol, 88%). 1H NMR: δ 6.98-
7.15 (m, 6H, Ar), 6.83 (t, 1H, py), 6.38 (d, 2H, py), 5.88 (s, 5H,
2
Cp), 4.45 (AB quartet, J HH ) 20.9 Hz, 4H, NCH2), 2.55 and
1.98 (s, 6H each, Me). 13C{1H} NMR: δ 161.75, 159.36, 137.38,
134.89, 132.19, 129.33, 128.76, 124.35, 116.90, 116.43 (C5H5),
65.39, 19.00, 18.75.
(BDP P )Zr (C4H6) (5a ). To a diethyl ether (25 mL) suspen-
sion of compound 1a (0.100 g, 0.162 mmol) was added 1.3 equiv
of Mg(C4H6)‚2THF (0.044 g, 0.198 mmol) at -20 °C. The
suspension was stirred for 12 h. The solvent was removed in
vacuo. The resulting solid was extracted with toluene (3 ×
10 mL) and filtered through Celite to give a bright-yellow

Zirconium Alkyl Complexes
Organometallics, Vol. 17, No. 23, 1998 5177
solution. The solvent was removed in vacuo, and the solid was
dissolved in a minimum amount of diethyl ether and cooled
to -30 °C for 12 h. Yellow crystalline 5a was isolated by
filtration and dried under vacuum (0.093 g, 0.155 mmol, 96%).
1H NMR: δ 7.0-7.15 (m, 2H, Ar), 6.98 (t, 1H, py), 6.57 (d, 1H,
py), 6.49 (d, 1H, py), 5.07 (s, 2H, NCH2), 5.03 (m, 2H,
ZrCH2CH, Hm), 4.72 (s, 2H, NCH2), 4.00 (sept, 2H, CHMe2),
3.56 (m, 2H, ZrCH2CH, Ha), 3.08 (sept, 2H, CHMe2), 2.38 (sept,
6H each, CHMe2), 1.33, 1.23, 1.16 and 1.01 (d, 6H each,
CHMe2), 0.28 (m, 2H, ZrCH2CH, Hs). 13C{1H} NMR: δ 165.52,
164.58, 150.75, 149.92, 146.10, 143.78, 137.69, 125.21, 124.89,
124.31, 123.46, 119.35, 117.65, 117.20, 67.99, 67.73, 58.20,
28.48, 27.98, 27.78, 27.48, 24.33, 23.27. Satisfactory elemental
analysis was not obtained due to incomplete combustion.
Different combustion additives were used without success.
(BDEP )Zr (C4H6) (5b). The preparation of compound 5b
is identical to that for complex 5a . Compound 1b (0.100 g,
0.178 mmol) and C4H6Mg‚2THF (0.044 g, 0.198 mmol) gave
yellow crystalline 5b (0.083 g, 0.152 mmol, 85%). 1H NMR:
δ 7.0-7.15 (m, 2H, Ar), 6.97 (t, 1H, py), 6.59 (d, 1H, py), 6.51
(d, 1H, py), 4.92 (m, 2H, ZrCH2CH, Hm), 4.83 (s, 2H, NCH2),
4.47 (s, 2H, NCH2), 3.41 (m, 2H, ZrCH2CH, Ha), 2.97 (m, 4H,
CH2Me), 2.38 (m, 4H, CH2Me), 1.24 and 1.11 (t, 6H each,
CH2Me), 0.16 (m, 2H, ZrCH2CH, Hs). 13C{1H} NMR: δ 165.64,
164.75, 140.95, 138.82, 137.58, 129.35, 126.39, 125.46, 124.72,
124.36, 119.64, 117.79, 117.34, 67.06, 66.57, 58.50, 23.66,
23.36, 15.73, 15.29.
(BDMP )Zr (C4H6) (5c). The preparation of compound 5c
is identical to that for complex 5a . Compound 1a (0.100 g,
0.198 mmol) and C4H6Mg‚2THF (0.049 g, 0.249 mmol) gave
yellow crystalline 5c (0.093 g, 0.190 mmol, 96%). 1H NMR: δ
6.8-7.15 (m, 2H, Ar), 6.91 (t, 1H, py), 6.62 (d, 1H, py), 6.52
(d, 1H, py), 4.98 (m, 2H, ZrCH2CH, Hm), 4.47 (s, 2H, NCH2),
4.36 (s, 2H, NCH2), 3.42 (m, 2H, ZrCH2CH, Hs), 2.39 and 1.95
(s, 6H each, Me), 0.17 (m, 2H, ZrCH2CH, Ha). 13C{1H} NMR:
δ 165.69, 164.80, 153.40, 151.57, 137.47, 135.49, 133.38,
129.23, 128.24, 124.28, 123.94, 119.59, 117.76, 117.31, 65.31,
64.73, 58.54, 18.36. Anal. Calcd for C27H31N3Zr: C, 66.35;
H, 8.60; N, 6.39. Found: C, 66.71; H, 8.44; N, 6.42.
4.78 (m, 1H, ZrCH2CHdCHCH2), 3.98 (sept, 1H, CHMe2), 3.59
(sept, 1H, CHMe2), 3.48 (m, 2H, CHMe2), 3.02 (m, 2H, ZrCH2-
CHdCHCH2), 2.43 (dd, 1H, ZrCH2CHdCHCH2), 1.70 (dd, 1H,
ZrCH2CHdCHCH2), 1.20-1.40 (6 doublets, 18H, CHMe2), 1.09
(d, 3H, CHMe2), 1.07 (d, 3H, CHMe2), -0.03 (s, 9H, SiMe3).
13C{1H} NMR: δ 193.83, 172.22, 164.53, 164.04, 147.97,
147.35, 147.06, 146.67, 145.75, 145.55, 141.35, 138.22, 126.52,
125.73, 124.72, 124.58, 124.48, 123.94, 123.34, 117.61, 68.11,
67.52, 67.27, 42.84, 28.74, 28.61, 28.31, 28.25, 28.07, 27.22,
27.09, 23.88, 23.80, 23.21, 22.73, 1.42.
(BDP P )Zr (C6H9Bu ) (8a ). The preparation of compound
8a is identical to that of complex 6a . Compound 5a (0.250 g,
0.43 mmol) and 1-hexene (0.100 g, 1.19 mmol) gave white
crystalline 8a (0.213 g, 0.31 mmol, 73%). 1H NMR: δ 7.05-
7.20 (m, 6H, Ar), 6.87 (t, 1H, py), 6.45 (d, 1H, py), 6.44 (d, 1H,
2
py), 5.41 (m, 1H, ZrCH2CHdCHCH2), 4.80 (AB quartet, J HH
2
) 19.8 Hz, 2H, NCH2), 4.69 (AB quartet, J HH ) 19.8 Hz, 2H,
NCH2), 3.80 (m, 3H, CHMe2), 3.80 (m, 1H, ZrCH2CHdCHCH2),
3.38 (sept, 1H, CHMe2), 3.17 (m, 1H, ZrCH2CHBu), 2.93 (broad
d, 1H, ZrCH2CHdCHCH2), 2.51 (dd, 1H, ZrCH2CHdCHCH2)
2.17 (m, 1H, ZrCH2CHdCHCH2), 1.72 (m, 1H, ZrCH2CHBu),
1.46 (m, 1H, ZrCH2CHdCHCH2), 1.28-1.43 (5 doublets, 15H,
CHMe2), 1.28-1.43 (buried, 6H, CH2CH2CH2), 1.22 (d, 3H,
CHMe2), 1.08 (d, 3H, CHMe2), 1.05 (d, 3H, CHMe2), 0.92 (t,
3H, CH2CH3), 0.12 (t, 1H, ZrCH2CHBu). 13C{1H} NMR: δ
163.03, 162.82, 149.55, 148.22, 146.27, 145.90, 145.51, 137.76,
135.93, 125.79, 125.08, 124.45, 124.23, 123.86, 123.63, 120.48,
117.18, 67.19, 67.01, 66.51, 56.95, 54.10, 42.49 (ZrCHBuCH2),
41.37, 31.11, 29.50, 29.39, 28.03, 27.67, 27.54, 27.46, 26.96,
26.53, 24.80, 24.47, 24.04, 23.47, 14.51. Anal. Calcd for
C
41H59N3Zr: C, 71.87; H, 8.68; N, 6.13. Found: C, 72.00; H,
8.80; N, 6.12.
X-r a y Cr ysta llogr a p h ic An a lysis. A suitable crystal of
5a was grown from a saturated ether solution at -30 °C.
Crystal data may be found in Table 1. Data were collected on
a Siemens Smart system CCD diffractometer. The data were
collected in the range of θ ) 1.47-21.49° (-20 ) h ) 21, -21
) k ) 15, -32 ) l ) 35). Unit-cell parameters were calculated
from reflections obtained from 60 data frames collected at
different sections of the Ewald sphere. No absorption correc-
tions were necessary (µ ) 3.36 cm-1). The molecule is located
on a 2-fold axis with the diene disordered with a 50/50 site
occupation. The diene was refined as a flat, rigid body with
chemically equivalent bonds restrained to be equal. A co-
crystallized, partially occupied ether solvent molecule was
located severely disordered at a 4-fold rotoinversion axis with
a net occupancy of 0.35. The Flack parameter refined to 0.0(2),
indicating that the true hand of the data was correctly
determined. All non-hydrogen atoms were refined with aniso-
tropic displacement coefficients. All hydrogen atoms were
treated as idealized contributions. The structure was solved
by direct methods, completed by subsequent Fourier syntheses,
and refined with full-matrix least-squares methods. All scat-
tering factors and anomalous dispersion coefficients are con-
tained in the SHELXTL 5.03 program library.26 In the final
difference Fourier synthesis the electron density fluctuates in
(BDP P )Zr (C6H6P r 2) (6a ). A benzene (10 mL) solution of
compound 5a (0.100 g, 0.17 mmol) and an excess of 4-octyne
(0.050 g, 0.45 mmol) were heated in a glass pressure vessel to
90 °C for 12 h. The solution changed from yellow to orange.
The solvent was removed in vacuo, and the resulting solid was
recrystallize from a toluene/pentane mixture (10/50) at -30
°C. White crystalline 6a was isolated by filtration and dried
under vacuum (0.098 g, 0.014 mmol, 84%). 1H NMR: δ 7.25-
7.10 (m, 6H, Ar), 7.00 (t, 1H, py), 6.55 (br d, 2H, py), 5.35 (m,
1H, ZrCH2CHdCHCH2), 5.01 (AB quartet, 2J HH ) 20.6 Hz, 2H,
2
NCH2), 4.94 (AB quartet, J HH ) 20.6 Hz, 2H, NCH2), 4.42
(m, 1H, ZrCH2CHdCHCH2), 4.05 (sept, 1H, CHMe2), 3.66
(sept, 1H, CHMe2), 3.61 (sept, 1H, CHMe2), 3.55 (sept, 1H,
CHMe2), 3.12 (d, 2H, ZrCH2CHdCHCH2), 2.45 (dd, 1H, ZrCH2-
CHdCHCH2), 2.25 (m, 2H, CH2CH2CH3), 2.1 (m, 2H, CH2CH2-
CH3), 1.60 (m, 1H, ZrCH2CHdCHCH2), 1.60 (m, 2H, CH2CH2-
CH3), 1.50-1.10 (8 doublets, 3H each, CHMe2), 1.50-1.10
(buried, 2H, CH2CH2CH3), 0.88 (t, 3H, CH2CH2CH3), 0.60 (t,
3H, CH2CH2CH3). 13C{1H} NMR: δ 187.97, 168.97, 163.87,
163.51, 148.38, 147.04, 146.43, 145.84, 145.72, 138.82, 137.91,
129.29, 126.28, 125.45, 124.62, 124.52, 124.38, 123.27, 119.23,
117.38, 117.31, 68.06, 67.66, 67.27, 42.23, 38.91, 34.83, 28.52,
28.44, 28.27, 28.20, 28.07, 27.87, 27.64, 27.35, 24.92, 24.27,
24.07, 23.96, 23.45, 23.25, 15.52, 15.40.
the range 0.551--0.489 e Å-3
.
Ackn owledgm en t. Fundingfrom theNSERC(Canada)
in the form of a Research Grant to D.H.M. and Union
Carbide Canada is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: The final crystal-
lographic atomic coordinates, equivalent isotropic thermal
parameters, hydrogen atom parameters, anisotropic thermal
parameters, complete tables of bond lengths and angles, and
ORTEPs for 2a and 5a (19 pages). Ordering information can
be found on any current masthead page.
(BDP P )Zr (C6H7SiMe3) (7a ). The preparation of compound
7a is identical to that of complex 6a . Compound 5a (0.050 g,
0.09 mmol) and trimethylsilylacetylene (0.020 g, 0.20 mmol)
gave white crystalline 7a (0.046 g, 0.07 mmol, 79%). 1H
NMR: δ 8.02 (t, 3J HH ) 2.7 Hz 1H, (SiMe3)CdCH), 7.10-7.25
(m, 6H, Ar), 6.98 (d, 1H, py), 6.58 (d, 1H, py), 6.55 (d, 1H, py),
5.38 (m, 1H, ZrCH2CH)CHCH2), 5.03 (AB quartet, 2J HH ) 20.6
Hz, 2H, NCH2), 4.99 (AB quartet, 2J HH ) 20.3 Hz, 2H, NCH2),
OM980146V
(26) SHELXTL Version 5; Siemans Analytical X-ray Instruments
Inc.: Madison WI, 1994.