Synthesis and structure of group 4 iminophosphonamide complexes

Article abstract of DOI:10.1021/om0492350

The syntheses of a variety of iminophosphonamide (PN₂) ligands (2a-f), the corresponding hydrochloride salts (1a-c), and a number of bis(PN₂) dichloride complexes of group 4 (3a-e) and their corresponding dialkyls (5a-e) are described. A novel monosubstituted PN ₂ "ate" complex 4 was prepared from ligand 2f and Zr(NMe₂)₄ on treatment with excess Me ₂NH·HCl. Piano-stool PN₂ zirconium dichloride complexes 6a-h were accessible on treatment of CpZr(NMe₂)₃ (Cp = C₅H₅, Cp*) with PN₂ ligands 2a-e, followed by metathesis with excess Me₃SiCl or Me ₂NH·HCl (6a-g) or at low T with ethereal HCl (6h). Dialkyl derivatives 8a-h could be prepared from 6a-h or directly from ligands 2 and CpMMe₃ (Cp = C₅H₅, Cp*; M = Ti or Zr). The intermediate Cp(PN₂)Zr(NMe₂)₂, precursor to 6h, rearranged to the novel terminal difluoride complexes 7a,b at room temperature. A variety of complexes 3 and 6 or their corresponding alkyl derivatives have been characterized by X-ray crystallography. In addition, the novel "ate" complex 4 and difluoride complexes 7a,b have been structurally characterized in this manner. The structures of 7a,b in the solid state reveal strong, intramolecular coordination of the NMe₂ group to the metal center, resulting in eight-coordinate complexes. One of these complexes is fluxional in solution, suggesting rapid exchange of bound versus free NMe₂ groups coupled with the formation of coordination stereoisomers.

Full text of DOI:10.1021/om0492350

494
Organometallics 2005, 24, 494-507
Synthesis and Structure of Group 4
Iminophosphonamide Complexes
Rainer Vollmerhaus,† Robert Tomaszewski,† Pengcheng Shao,†
Nicholas J. Taylor,† Kevin J. Wiacek,‡ Stewart P. Lewis,‡
Abdulaziz Al-Humydi,‡ and Scott Collins*,‡
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and
Department of Polymer Science, University of Akron, Akron, Ohio 44325-3909
Received October 4, 2004
The syntheses of a variety of iminophosphonamide (PN2) ligands (2a-f), the corresponding
hydrochloride salts (1a-c), and a number of bis(PN2) dichloride complexes of group 4 (3a-
e) and their corresponding dialkyls (5a-e) are described. A novel monosubstituted PN2 “ate”
complex 4 was prepared from ligand 2f and Zr(NMe2)4 on treatment with excess Me2NH‚
HCl. Piano-stool PN2 zirconium dichloride complexes 6a-h were accessible on treatment of
CpZr(NMe2)3 (Cp ) C5H5, Cp*) with PN2 ligands 2a-e, followed by metathesis with excess
Me3SiCl or Me2NH‚HCl (6a-g) or at low T with ethereal HCl (6h). Dialkyl derivatives 8a-h
could be prepared from 6a-h or directly from ligands 2 and CpMMe3 (Cp ) C5H5, Cp*; M
) Ti or Zr). The intermediate Cp(PN2)Zr(NMe2)2, precursor to 6h, rearranged to the novel
terminal difluoride complexes 7a,b at room temperature. A variety of complexes 3 and 6 or
their corresponding alkyl derivatives have been characterized by X-ray crystallography. In
addition, the novel “ate” complex 4 and difluoride complexes 7a,b have been structurally
characterized in this manner. The structures of 7a,b in the solid state reveal strong,
intramolecular coordination of the NMe2 group to the metal center, resulting in eight-
coordinate complexes. One of these complexes is fluxional in solution, suggesting rapid
exchange of bound versus free NMe2 groups coupled with the formation of coordination
stereoisomers.
Introduction
[RC(NR′)2 ) CN2] as catalysts in ethylene or propylene
polymerization. This ligand is a hard σ-donor, which can
contribute up to 5e (3σ + 2π) on coordination to a d0
metal.2 On activation with PMAO in hydrocarbon
media, both bis(CN2)3 and mixed Cp(CN2)4 complexes
of Ti and Zr were active in ethylene, while the former
were also active in propylene polymerization; however,
compared with Cp2ZrX2 complexes, these 14-electron
complexes were approximately 102-103 times less active
under similar conditions of temperature and pressure.
Further, some of these complexes [e.g., Cp(CN2)ZrCl2,
R ) SiMe3, R′ ) Ph] were said to be almost inactive in
olefin polymerization;4a,b in these cases, thermal insta-
bility of cationic alkyls generated in situ from neutral
catalyst precursors was believed to be responsible for
this finding.
The synthesis of novel group 4 complexes is of
considerable interest in the context of olefin polymeri-
zation using “non-metallocene” catalysts.1 A wide vari-
ety of complexes based on the use of surrogates for the
Cp ligand have been prepared and many are active in
ethylene or R-olefin polymerization. However, the
polymerization activities of isoelectronic (or even iso-
lobal) complexes differ dramatically and often in a
contradictory manner. Establishing fundamental trends
in, for example, catalyst activity with respect to param-
eters such as total electron count and the steric and
electronic effect of ligand substituents has been prob-
lematic. These difficulties arise through a number of
complicating factors such as the efficiency of activation
of catalyst precursors with typical cocatalysts, particu-
larly methyl aluminoxane (PMAO), the stability of the
active catalyst (or precatalyst) with respect to irrevers-
ible deactivation or reversible inhibition processes, and
intrinsic electronic or steric effects on monomer coor-
dination and insertion rates.
More recently, less-hindered versions of mixed
Cp(CN2)ZrMe2 complexes (Cp ) η5-C5H5, η5-Cp*; R )
(2) (a) Barker, J.; Kilner, M. Coord. Chem. Rev. 1994, 133, 219. (b)
Edelmann, F. T. Coord. Chem. Rev. 1994, 137, 403.
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1995, 503, 307. (b) Flores, J. C.; Chien, J. C. W.; Rausch, M. D.
Organometallics 1995, 14, 1827. (c) Littke, A.; Sleiman, N.; Bensimon,
C.; Richeson, D. S.; Yap, G. P. A.; Brown, S. J. Organometallics 1998,
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Some time ago, a number of workers elected to study
group 4 complexes based on the amidinate ligand
* To whom correspondence should be addressed. E-mail: collins@
uakron.edu.
† University of Waterloo.
‡ University of Akron.
(1) (a) Gibson, V. C.; Spitzmesser, S. K. Chem. Rev. 2003, 103, 283.
(b) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem., Int.
Ed. 1999, 38, 428.
10.1021/om0492350 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 01/07/2005

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 495
Me and R′ ) Et, cHx, tBu, etc.) have been shown to effect
the living polymerization of 1-hexene or other sterically
hindered alkenes in chlorobenzene solution on activation
with either [PhNMe2H][B(C6F5)4] or [Ph3C][B(C6F5)4].5
Detailed study of these cationic alkyl-Zr complexes has
indicated that they are reasonably stable in such media
and are less prone to â-H elimination than their Cp2
counterparts. Further, bimolecular alkyl group ex-
change processes are facile at higher Zr concentrations5e,f
and are responsible for erosion of tacticity seen using
chiral initiators of this type. Although the polymeriza-
tion of ethylene or propylene has not been reported in
the open literature using these initiators, the activity
in hexene polymerization (e105 g C6H12/mol Zr × h)
suggests that values in the range 106-107 g monomer/
mol Zr × h at 25 °C in this polar solvent are not
unlikely.
Several years ago we were intrigued by the origins of
the low activities observed for CN2 complexes of group
4 in ethylene polymerization, at least when activated
under conventional conditions using PMAO in hydro-
carbon media. We suspected either that the precatalysts
were inefficiently activated using PMAO or were insuf-
ficiently stable under the conditions studied or that
unfavorable steric/electronic effects were at play here.
Further, although the CN2 ligand is sterically demand-
ing with a cone angle comparable to Cp or Cp* depend-
ing on substitution,2 it is an inherently two-dimensional
ligand, which might make such complexes more sus-
ceptible to bimolecular inhibition and/or degradation
processes, compared with their Cp analogues.
We reasoned that a more three-dimensional analogue,
such as the iminophosphonamide [R2P(NR′)2 ) PN2]
ligand,6 where the tetrahedral P(V) atom is thought to
represent a minimal electronic perturbation to trigonal
C(IV), would be a suitable choice of ligand to investigate
such issues. Preliminary work revealed that complexes
derived from these ligands had ethylene polymerization
activities that rivaled bent metallocene complexes when
activated by PMAO under comparable conditions.7
Herein we report full details for the synthesis of a
variety of PN2 ligands and the synthesis and solid-state
structures of group 4 complexes derived from them. In
a subsequent paper we will report on the utility of these
complexes in ethylene polymerization and their use for
living polymerization of hexene.8
Scheme 1
Results and Discussion
Synthesis of PN2 Ligands and PN2 Complexes.
A number of PN2 complexes of the group 4 metals had
been prepared and characterized prior to our work in
this area; many of these compounds were synthesized
by the reaction of an N,N,N′-tris(trimethylsilyl)-PN2
ligand with the corresponding titanium or zirconium
(IV) chloride.6 Monosubstituted complexes were gener-
ally accessible via this route and were typically di-
nuclear with halide bridges. In contrast, there were very
few reports of disubstituted and no reports of mixed
Cp(PN2) complexes prior to our work. Further, the range
of substituents on both P and N in these complexes was
rather limited, because of the need for trimethylsilyl
chloride elimination as a key step in complex formation.
We thus focused our attention on a more general
approach to the synthesis of these complexes and elected
to use amine elimination9 as a complementary route to
both mono- and disubstituted PN2 complexes. Further,
we envisaged that the nature of the R and R′ groups on
P and N, respectively, would alter the steric and
electronic properties of these ligands so that we could
study fundamental trends in insertion reactivity with
these complexes. Thus, a variety of PN2 ligands differing
in their steric and/or electronic properties were targeted.
As shown in Scheme 1, a variety of NAr-, NR-, or
NSiMe3-substituted PN2 ligands were accessible by one
of two established routes. With electron-rich amines or
anilines, nucleophilic disubstitution of diphenylphos-
phoryl trichloride10 proved expedient (but wasteful of
1° amine) and furnished the corresponding PN2‚HCl
salts 1 in high yields. This approach was unsuccessful
in the case of electron-deficient anilines such as C6F5-
NH2; in such cases, a complementary method involving
the Stau¨dinger reaction of 2° phosphines with 2 equiv
of an aryl- or trimethysilyl-azide11 proved efficient,
affording access to the PN2 ligands 2 directly. Although
the hydrochloride salts 1 are useful reagents in their
own right (vide infra), they can be transformed to
ligands 2 on treatment with KOtBu in ether, while the
former are accessible from the latter on reaction with
anhydrous HCl in ether (as in the case of 1f). All of these
compounds are sensitive toward hydrolysis in solution
and are best stored in a glovebox or desiccator under
N2.
(5) (a) Jayaratne, K. C.; Sita, L. R. J. Am. Chem. Soc. 2000, 122,
958. (b) Jayaratne, K. C.; Keaton, R. J.; Henningsen, D. A.; Sita, L. R.
J. Am. Chem. Soc. 2000, 122, 10490. (c) Keaton, R. J.; Jayaratne, K.
C.; Fettinger, J. C.; Sita, L. R. J. Am. Chem. Soc. 2000, 122, 12909.
(d) Keaton, R. J.; Jayaratne, K. C.; Henningsen, D. A.; Koterwas, L.
A.; Sita, L. R. J. Am. Chem. Soc. 2001, 123, 6197. (e) Jayaratne, K. C.;
Sita, L. R. J. Am. Chem. Soc. 2001, 123, 10754. (f) Zhang, Y.; Keaton,
R. J.; Sita, L. R. J. Am. Chem. Soc. 2003, 125, 9062. (g) Zhang, Y.;
Sita, L. R. J. Am. Chem. Soc. 2004, 126, 7776.
(6) (a) Witt, M.; Roesky, H. W.; Stalke, D.; Pauer, F.; Henkel, T.;
Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1989, 2173. (b)
Recknagel, A.; Witt, M.; Edelmann, F. T. J. Organomet. Chem. 1989,
371, C40. (c) Recknagel, A.; Steiner, A.; Noltemeyer, M.; Brooker, S.;
Stalke, D.; Edelmann, F. T. J. Organomet. Chem. 1991, 414, 327. (d)
Kilimann, U.; Noltemeyer, M.; Schafer, M.; Herbst-Irmer, R.; Schmidt,
H.-G.; Edelmann, F. T. J. Organomet. Chem. 1994, 469, C27. (f) Muller,
E.; Muller, J.; Olbrich, F.; Bruser, W.; Knapp, W.; Abeln, D.; Edelmann,
F. T. Eur. J. Inorg. Chem. 1998, 87, and references therein.
The free PN2 ligands 2 should, in principle, give rise
to different sets of NMR signals associated with the
(7) (a) Preliminary communication: Vollmerhaus, R.; Shao, P.;
Taylor, N. J.; Collins, S. Organometallics 1999, 18, 2731. (b) Voll-
merhaus, R.; Collins, S.; Wang, S. US Patent 6,268,448, 2001, 13 pp.
(8) Vollmerhaus, R.; Al-Humydi, A.; Tomaszewski, R.; Shao, P.;
Taylor, N. J.; Collins, S. Manuscript in preparation.
(9) (a) Diamond, G. M.; Rodewald, S.; Jordan, R. F. Organometallics
1995, 14, 5. (b) Diamond, G. M.; Jordan, R. F.; Peterson, J. L. J. Am.
Chem. Soc. 1996, 118, 8024.
(10) Cristau, H.-J.; Garcia, C. Synthesis 1990, 315.
(11) Paciorek, K.; Kratzer, R. J. Org. Chem. 1996, 31, 2426.

496 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
Scheme 2
adopt cis-quasi-octahedral structures with approximate
C2 symmetry (vide infra). We suspect the higher sym-
metry observed in solution is due to rapid rotation of
these ligands about the P- - -Zr axes, as has been
documented for the corresponding amidinate ana-
logues.3,15
Dimethyl derivatives 5a-d can be readily pre-
pared from dichloride complexes 3 with either MeLi or
MeMgBr in ether solution (eq 2). The dibenzyl complex
5e was prepared from 3c using 2 equiv of PhCH2K in
toluene suspension. The dialkyls 5 are all readily
hydrolyzed but are not pyrophoric; they merely smolder
in air. As with their dichloride precursors, complexes 5
exhibit NMR spectra consistent with time-averaged C2v
symmetry.
inequivalent NR moieties in these compounds. In prac-
tice this was not usually observed in the 1H NMR
spectra of ligands 2a-e at room temperature; however,
the 19F NMR spectrum of 2f clearly showed evidence
for fluxional behavior at room temperature, consisting
of three line-broadened resonances. On cooling to -60
°C, decoalescence of these into two sets of o-, m-, and
p-F resonances was observed. We suspect that rapid
exchange of the reasonably acidic N-H proton, in a
bimolecular fashion, analogous to the process known for
carboxylic acids or amidines,12 is at play here.
An “atom-economical” route to bis(PN2) dichloride
complexes 3a-e involves direct reaction of hydrochlo-
ride salts 1a,b and 1f with Zr(NMe2)4 or Ti(NMe2)4 in a
2:1 ratio (Scheme 2). We suspect these reactions proceed
via initial formation of M(NMe)2Cl2, which has been
shown to be a useful starting material in amine elimi-
nation reactions.13 Alternate routes to complexes 3
involved amine elimination reactions of Zr(NMe2)4 with
2 equiv of the “free” PN2 ligand 2 to furnish the expected
bis(amido)PN2 complexes in high yield. Generally such
intermediates were not isolated but converted to the
corresponding dichloride complexes 3 on treatment with
either anhydrous Me2NH‚HCl or an excess of Me3SiCl
(e.g., synthesis of 3e, Scheme 2).14 Although not sys-
tematically investigated as a route to monosubstituted
PN2 complexes, the 1:1 reaction of Zr(NMe)4 with PN2
ligand 2c cleanly furnished the expected tris(amido)
complex; treatment with a 4-fold excess of Me2NH‚HCl
furnished the novel [Me2NH2][PN2ZrCl4] complex 4 in
variable yield (eq 1). This compound was characterized
by X-ray crystallography (vide infra), but its chemistry
has not been further studied.
Piano-stool, PN2 zirconium dichloride complexes 6a-g
were available through reaction of ligands 2c-e with
CpZr(NMe2)3 [Cp ) C5H5, C5Me5], followed by treatment
with either Me2NH‚HCl or excess Me3SiCl (eq 3). In this
case, it was also convenient to use salts 1a,b (which are
easily purified) even though the intermediate (dimethyl-
amido)chloride complexes had to be converted to the
final products 6a,b using the same methods.
In the case of ligand 2f (R′ ) C6F5, R ) Ph) amine
elimination involving CpZr(NMe2)3 proceeded in an
unexpected manner to give a solid, sparingly soluble in
hexane, which is uncharacteristic of these piano-stool
bis(amido) complexes. The 19F NMR spectrum of this
mixture in C6D6 featured multiple resonances in the
region δ -100 to -200, characteristic of perfluoroaryl
groups, and multiple signals at δ 0 to +100 ppm, some
with obvious 19F-19F coupling. The 1H NMR spectrum
indicated fluxional behavior for the PPh2, Cp, and NMe2
groups and suggested the presence of at least two
different compounds based on the Cp region. Crystal-
lization of this material from toluene allowed for sepa-
The dichloride complexes 3 are sensitive to hydrolysis,
particularly in solution, but are nicely crystalline and
can be readily purified. Their solution 1H, 13C, and,
where applicable, 19F NMR spectra are consistent with
time-averaged C2v symmetry (see Experimental Sec-
tion). However, in the solid state, all of these complexes
(12) (a) Raczynska, E.; Oszczapowicz, J. Tetrahedron 1985, 41, 5175.
(b) Genkina, G. K.; Korolev, B. A.; Gilyarov, V. A.; Stepanov, B. I.;
Kabachnik, M. I. Zh. Obsh. Khim. 1969, 39, 326; Chem. Abstr. CA 71:
12396.
(13) (a) Murata, K.; Hori, J.; Yoshida, M. Eur. Pat. Appl. 834514,
1998, 19 pp. (b) Fritze, C.; Erker, G.; Duda, L. Ger. Offen. DE 19741989,
1999, 12 pp. (c) Duncan, A. P.; Mullins, S. M.; Arnold, J.; Bergman, R.
G. Organometallics 2001, 20, 1808.
(14) (a) Kim, I.; Jordan, R. F. Macromolecules 1996, 29, 489. (b)
Rahim, M.; Taylor, N. J.; Xin, S.; Collins, S. Organometallics 1998,
17, 1315.
(15) Koterwas, L. A.; Fettinger, J. C.; Sita, L. R. Organometallics
1999, 18, 4183, and references therein.

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 497
Scheme 3
the possibility of coordination stereoisomers (e.g., cis
versus trans fluorides) being present in solution.
As with their bis(PN2) counterparts, dialkyl zirconium
derivatives 8a, 8c, and 8e-g were accessible via con-
ventional reactions with Grignard or organolithium
reagents (Scheme 4). However, control of stoichiometry
and/or reaction conditions was crucial since in many
cases these mixed Zr complexes are susceptible to
disproportionation into (PN2)2ZrR2 and Cp2ZrR2, a
process that appears facilitated by an excess (local or
otherwise) of R-M (M ) MgBr or Li). Similar observa-
tions have been made during the synthesis of Cp(CN2)-
ZrMe2 complexes via this route.4a-c,5
In view of this undesired complexity, a better route
to Ti and Zr alkyls 8 was developed; some of these Zr
complexes were among the most active in olefin polym-
erization,7,8 and gram quantities were needed for mecha-
nistic work in support of these studies.8 As shown in
Scheme 4, reaction of ligands 2a,b, and 2d with
CpMMe3 (Cp ) C5H5, M ) Ti or Zr) cleanly furnished
the corresponding alkyls 8b-d and 8f often in close to
quantitative yield. Since the complex CpZrMe3 is un-
stable in solution above -20 °C,17 alkane elimination
reactions involving the use of this precursor required
in situ formation from CpZrCl3 and MeLi prior to the
addition of ligands 2. In these cases it was preferable
to use a slight excess of MeLi, to facilitate clean and
rapid formation of CpZrMe3, followed by treatment with
anhydrous and degassed Me3SiCl5 prior to the addition
of ligand 2. This procedure avoided disproportionation
of products 8 due the presence of excess MeLi in these
mixtures (vide supra).
Structure of PN2 Complexes. A number of these
Ti and Zr complexes have been characterized by X-ray
crystallography. The molecular structures of complexes
3a and 3b, 5b and 5e, 4, 6b7 and 8d, and 7a and 7b
appear in Figures 1-5, respectively, while selected
crystallographic and refinement data appear in Table
1, and selected metrical parameters appear in Tables 2
and 3, respectively. Full details of these structures are
included as Supporting Information. In earlier work, we
had also reported the structures of 3c and 6b7 and have
included relevant metrical data in Tables 3 and 4 for
the sake of comparison and discussion.
ration of these compounds, and X-ray structural deter-
minations on both revealed that these compounds were
the novel isomeric zirconium difluoride complexes 7a
and 7b (Scheme 3). The former compound, in which the
PN2 ligand is symmetrically substituted by the o-Me2N-
C6F4- group, was the major isomer present in the
original mixture (ca. 2:1). Evidently, these complexes
form via intramolecular, nucleophilic substitution of the
C6F5 rings at the o-position in the putative bis(NMe2)
intermediate, which is unstable at room temperature.16
We have been unable to isolate the latter compound
under any conditions. Its presence is inferred from the
1H and 19F NMR spectra of a mixture of 2f and
CpZr(NMe2)3 at low temperature and by the observation
that amine elimination, followed by treatment with
anhydrous HCl in ether at -78 °C, cleanly furnished
the expected dichloride complex 6h (Scheme 3).
Interestingly, of these two difluoride isomers, only 7a
appears fluxional in solution. The 1H, 19F, and 31P NMR
spectra of 7b were consistent with the static structure
shown in Scheme 3 (see Experimental Section). As to
1
the fluxional behavior of 7a, whose 19F and H NMR
spectra were variable and complex over the T range -80
to +100 °C, we have been unable to completely decipher
the nature of the processes responsible for this behavior.
We suspect, based on the X-ray structure which
features a dative interaction between one NMe2 group
and the Zr (vide infra), that a combination of reversible,
degenerate exchange of bound and free NMe2 groups,
coupled with hindered rotation about the N-Ar bonds
or P-Zr axis, is partly responsible for the behavior seen
for 7a. However, there are more than the expected
number of terminal F resonances in the 19F NMR
spectrum (two sets of doublets with different 19F-19F
coupling constants) and two different singlets in the
31P{1H} NMR spectrum of 7a. This behavior suggests
The bis(PN2) dichloride and dialkyl complexes 3 and
5 are characterized by quasi-octahedral geometries
featuring cis dichloride or dialkyl ligation. These com-
plexes have approximate local C2 symmetry in the solid
state. As would be expected, the M-N distances in the
PN2 ligands track with the identity of both the metal
Scheme 4

498 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
Figure 1. Molecular structures of complexes 3a and 3b with 30% thermal ellipsoids depicted and H atoms removed for
clarity.
Figure 2. Molecular structures of complexes 5b and 5e with 30% thermal ellipsoids depicted and H atoms removed for
clarity.
and the nature of the remaining ligands (Table 3), being
2.0-2.7% shorter on average in the case of dichloride
complexes 3 relative to the dialkyls 5. The magnitude
of the Ti-N distances [2.031(2)-2.118(2) Å] are 11.0-
14.6% shorter on average than the sum of the covalent
radii (2.38 Å), while the Zr-N distances [2.174(2)-
2.284(2) Å] are only about 2.6% shorter on average than
the corresponding distance (2.29 Å). Only the Ti-N
bonds could be considered to possess a significant
π-component on this basis.
is 64.7-66.8(1)° and 69.5-71.5(1)° in the case of Zr and
Ti, respectively. There is minor systematic variation of
this angle with respect to the remaining ligands, with
the angle being about 1.0-1.8(1)° more acute in the case
of the dialkyls 5 compared to analogous complexes 3.
The PN distances at 1.600-1.630(2) Å are intermediate
between single and double P-N bonds. Again, there is
a systematic variation in the P-N bond lengths, being
marginally shorter (e1%) on average in the dialkyls 5
compared with dichloride complexes 3; interestingly, the
P-N distances are essentially independent of the nature
of the metal in otherwise identical complexes [e.g.,
1.608-1.624(2) versus 1.608-1.628(2) Å for 3b and 3a].
There are larger variations in the N-P-N angles in
these complexes, being more acute by about 1-2° in the
dichlorides versus the dialkyls and by a similar amount
for Ti versus Zr. Since the overall variation in this angle
is smaller than for the corresponding N-M-N angles
The bite angle of the PN2 ligand is remarkably
consistent over a range of ligands and complexes and
(16) A dimethylamido fluoride complex, a plausible intermediate
involved in the formation of 7a and 7b, has also been isolated from
these mixtures after short reaction times at room temperature and
has been characterized spectroscopically. Tomaszewski, R. Unpub-
lished results.
(17) Aitken, C.; Barry, J. P.; Gauvin, F.; Harrod, J. F.; Malek, A.;
Rousseau, D. Organometallics 1989, 8, 1732.

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 499
variation as a function of the M-N distances. Thus, in
3a the Zr-Cl distances of 2.466(1) and 2.478(1) Å are
about 2% longer than in 3c [2.436(1) and 2.431(1) Å],
which mirrors the variation seen in the corresponding
M-N distances (longer on average for 3c). The angle
defined by the metal and these two remaining ligands
varies from 86.5(1)° to 95.7(1)° with TiMe2 and ZrCl2
angles being at the lower and upper ranges, respec-
tively. The angle between these two ligands appears to
be independent of the metal as the R-M-R angles are
4.35(7)-4.4(1)° more acute than the corresponding Cl-
M-Cl angles for both Ti and Zr. Overall, the structures
of the Zr complexes are analogous to structurally
characterized bis(CN2) complexes featuring alkyl/aryl
substitution on N,3,18 the differences mainly evident in
the more acute bite angle of the CN2 ligand and the
somewhat shorter M-N distances in the case of the PN2
complexes.
A curious feature is evident in the structures of the
N-benzyl Ti complexes 3b and 5b. Namely, the geometry
at N(2) and N(4) is distorted from trigonal planar
toward tetrahedral. In the case of complex 3b the sum
of the angles about N(2) and N(4) respectively are
349.6(1)° and 350.5(1)°, while the corresponding values
for complex 5b are 349.8(1)° and 349.5(1)°, respectively.
At first this distortion was attributed to possible H-
bonding between the N-CH2Ph protons and the chloride
Figure 3. Molecular structure of the anionic portion of
“ate” complex 4 with 30% thermal ellipsoids depicted and
H atoms removed for clarity.
(ca. 4.4° in the case of 3a versus 3b) and these four-
membered rings are close to planar (Table 3), the
principle effect on changing the metal in these systems
is for the PN2 ligand to simply move farther away from
the (larger) metal with a lesser change in the angle at
P.
Finally, M-Cl and M-C distances in these structures
are within the normal range expected but do show a
Figure 4. Molecular structures of complexes 6b7 and 8d with 30% thermal ellipsoids depicted.
Figure 5. Molecular structures of complexes 7a and 7b with 30% thermal ellipsoids depicted and selected H atoms depicted.

500 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
Table 1. Selected Crystallographic and Refinement Data for PN2 Complexesa
3a
3b
4
5b
emp formula
fw
C
52H48Cl2N4P2Zr
C52H48Cl2N4P2Ti
909.68
monoclinic
P2(1)/c
a ) 10.605(1),
R ) 90
C20H36Cl4N3PSi2Zr
638.69
monoclinic
P2(1)/n
a ) 9.1834(9),
R ) 90
C53.85H53.55Cl0.15N4P2Tib
871.91
orthorhombic
Pbca
953.00
cryst syst
monoclinic
P2(1)/c
a ) 10.265(3),
R ) 90
space group
unit cell (Å and deg)
a ) 20.360(3),
R ) 90°
b ) 21.493(4),
â ) 93.02(1)
c ) 20.721(4)
γ ) 90
b ) 21.317(2),
â ) 90.32(1)
c ) 20.485(2),
γ ) 90
b ) 16.569(1),
â ) 90.54(1)
c ) 20.171(2),
γ ) 90
b ) 20.087(2),
â ) 90°
c ) 22.375(2),
γ ) 90°
volume (Å3)
Z
4565(2)
4630.9(8)
3069.1(5)
9151(2)
4
4
4
8
F(calcd) (Mg/m3)
1.387
1.305
1.382
1.266
abs coeff (mm-1
)
0.469
0.410
0.850
0.307
F(000)
1968
1896
1312
3674
cryst size (mm3)
θ range (deg)
0.42 × 0.37 × 0.34
2.14-25.00
8519
0.54 × 0.52 × 0.52
2.14-25.00
8606
0.56 × 0.36 × 0.21
2.36-25.00
5752
0.96 × 0.60 × 0.60
2.00-27.00
9952
no. of reflns coll
no. of indep reflns
max./min. transmn
no. of data/params
GOF (F2)
8040 [R(int) ) 0.0227]
0.874/0.846
8040/551
8138 [R(int) ) 0.0157]
0.833/0.814
8138/550
5394 [R(int) ) 0.0123]
0.846/0.741
5394/289
9952
0.847/0.762
9952/550
2.254
1.696
2.617
1.823
R indices [I>2σ(I)]
R1 ) 0.0295
wR2 ) 0.0602
R1 ) 0.0390
wR2 ) 0.0610
R1 ) 0.0357
wR2 ) 0.0735
R1 ) 0.0435
wR2 ) 0.0738
R1 ) 0.0214
wR2 ) 0.0497
R1 ) 0.0251
wR2 ) 0.0500
R1 ) 0.0421
wR2 ) 0.0906
R1 ) 0.0569
wR2 ) 0.0914
R indices (all data)
5e
7a
7b
8d
emp formula
fw
C
80H78N4P2Zr
C33H27F10N4PZr
791.78
C39.70H34.10Cl0.30F10N4PZrc
890.03
monoclinic
P2(1)/c
a ) 15.074(1),
R ) 90
C33H35N2PTi
538.50
monoclinic
P2(1)/c
a ) 8.998(1),
R ) 90
1248.62
cryst syst
monoclinic
triclinic
space group
unit cell (Å and deg)
Pnd
P1h
a ) 17.346(2),
R ) 90
a ) 9.946(1),
R ) 97.45(1)
b ) 12.725(2),
â ) 102.87(1)
c ) 12.947(1),
γ ) 90.50(1)
1582.7(3)
b ) 10.437(1),
â )103.93(1)
c ) 18.653(2),
γ ) 90
b ) 11.865(1),
â ) 101.42(1)
c ) 21.633(2),
γ ) 90
b ) 25.879(2),
â ) 97.86(1)
c ) 12.215(1),
γ ) 90
volume (Å3)
Z
3277.7(6)
2
3792.6(6)
2817.7(4)
4
2
4
F(calcd) (Mg/m3)
1.265
1.661
1.559
1.269
abs coeff (mm-1
)
0.265
0.489
0.438
0.385
F(000)
1312
796
1802
1136
cryst size (mm3)
θ range (deg)
0.74 × 0.52 × 0.36
2.25-25.00
5964
0.42 × 0.26 × 0.20
2.10-26.00
6592
0.74 × 0.70 × 0.38
2.13-28.00
9459
0.70 × 0.36 × 0.36
2.28-28.00
7210
no. of reflns coll
no. of indep reflns
max./min. transmn
no. of data/params
GOF (on F2)
5964
6214 [R(int) ) 0.0177]
0.914/0.880
6214/447
9126 [R(int) ) 0.0131]
0.856/0.750
9126/507
6804 [R(int) ) 0.0135]
0.886/0.863
6804/338
0.915/0.874
5964/787
2.165
1.545
2.116
1.940
R indices [I>2σ(I)]
R1 ) 0.0261
wR2 ) 0.0631
R1 ) 0.0275
wR2 ) 0.0633
R1 ) 0.0248
wR2 ) 0.0509
R1 ) 0.0318
wR2 ) 0.0515
R1 ) 0.0321
wR2 ) 0.0898
R1 ) 0.0400
wR2 ) 0.0905
R1 ) 0.0343
wR2 ) 0.0681
R1 ) 0.0463
wR2 ) 0.0689
R indices (all data)
a All data were collected at 160 K using graphite-monochromated Mo KR radiation (λ ) 0.71073 Å) and a Siemens P4 diffractometer
using ω scans. Unit cell parameters were determined from 25 general reflections well distributed in reciprocal space. Crystal stability
was monitored every 100 reflections. Structure solution and refinement was by Patterson and Fourier techniques with full-matrix least-
squares refinement on F2. Full details of the structures are included as Supporting Information. b Structure was disordered and could be
fit to a model in which 15% of the Ti-C(54) sites were disordered with a Ti-Cl(54) atom; see Supporting Information. c The structure
featured a disordered toluene molecule that could be modeled by inclusion of chlorobenzene at 30% occupancy; see Supporting Information.
d Flack parameter ) 0.00(14).
ligands in 3b, as the former were oriented toward the
distortion from planarity at N was also seen in the
dialkyl complex 5b and is of a similar magnitude.
Since there are no obvious inter- or intramolecular
contacts that might sterically distort these N-benzyl
substituents, we have to attribute this tendency toward
pyramidalization as intrinsic. Tentatively, delocalization
of lone pair electron density through P (or Ti) would
appear to be less effective in these N-alkyl (versus
N-aryl) Ti complexes. Although the P-N and M-N bond
lengths show differences (which are longer in the N-Bn
complexes) consistent with this interpretation, it should
latter in the solid-state structure. However, this same
(18) (a) Richter, J.; Edelmann, F. T.; Noltemeyer, M.; Schmidt, H.-
G.; Shmulinson, M.; Eisen, M. S. J. Mol. Catal. A: Chem. 1998, 130,
149-162. (b) Kincaid, K.; Gerlach, C. P.; Giesbrecht, G. R.; Hagadorn,
J. R.; Whitener, G. D.; Shafir, A.; Arnold, J. Organometallics 1999,
18, 5360. (c) Keaton, R. J.; Koterwas, L. A.; Fettinger, J. C.; Sita, L. R.
J. Am. Chem. Soc. 2002, 124, 5932. (d) Zhang, Y.; Kissounko, D. A.;
Fettinger, J. C.; Sita, L. R. Organometallics 2003, 22, 21. (e) Kissounko,
D. A.; Fettinger, J. C.; Sita, L. R. J. Organomet. Chem. 2003, 683, 29.
(f) Hagadorn, J. R.; McNevin, M. J.; Wiedenfeld, G.; Shoemaker, R.
Organometallics 2003, 22, 4818. (g) Kissounko, D. A.; Sita, L. R. J.
Am. Chem. Soc. 2004, 126, 5946.

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 501
Table 2. Selected Bond Lengths and Angles for Bis(PN2) Complexes
3a
3b
3c7
5b
5e
Bond Lengths [Å]
Zr(1)-N(1)
Zr(1)-N(2)
Zr(1)-N(3)
Zr(1)-N(4)
Zr(1)-Cl(1)
Zr(1)-Cl(2)
2.174(2) Ti(1)-N(3)
2.180(2) Ti(1)-N(1)
2.188(2) Ti(1)-N(2)
2.191(2) Ti(1)-N(4)
2.466(1) Ti(1)-Cl(1)
2.478(1) Ti(1)-Cl(2)
2.031(2) Zr(1)-N(1)
2.198(2) Ti(1)-N(1)
2.237(2) Ti(1)-N(4)
2.226(2) Ti(1)-N(3)
2.223(2) Ti(1)-N(2)
2.436(1) Ti(1)-C(53)
2.431(1) Ti(1)-C(54)
2.090(2) Zr(1)-N(2)
2.104(2) Zr(1)-N(3)
2.106(2) Zr(1)-N(4)
2.118(2) Zr(1)-N(1)
2.179(2) Zr(1)-C(60)
2.242(4)
2.254(3)
2.262(3)
2.284(3)
2.312(4)
2.313(4)
2.033(2) Zr(1)-N(2)
2.056(2) Zr(1)-N(3)
2.064(2) Zr(1)-N(4)
2.362(1) Zr(1)-Cl(1)
2.368(1) Zr(1)-Cl(2)
2.179a
2.367a
Zr(1)-C(53)
Ti(1)-Cl(54)
1.628(2) P(1)-N(2)
1.630(2) P(1)-N(1)
1.622(2) P(2)-N(4)
1.626(3) P(2)-N(3)
P(1)-N(2)
P(1)-N(1)
P(2)-N(4)
P(2)-N(3)
1.610(2) P(1)-N(2)
1.628(2) P(1)-N(1)
1.608(2) P(2)-N(4)
1.617(2) P(2)-N(3)
1.612(2) P(1)-N(2)
1.624(2) P(1)-N(1)
1.608(2) P(2)-N(4)
1.624(2) P(2)-N(3)
1.600(2) P(1)-N(1)
1.606(2) P(1)-N(2)
1.601(2) P(2)-N(3)
1.608(2) P(2)-N(4)
1.618(4)
1.619(3)
1.605(4)
1.623(3)
Bond Angles [deg]
N(1)-Zr(1)-N(2) 65.8(1)
N(3)-Zr(1)-N(4) 65.7(1)
N(1)-Zr(1)-N(2) 66.8(1)
N(3)-Zr(1)-N(4) 67.2(1)
Cl(1)-Zr-Cl(2)
N(2)-P(1)-N(1) 95.4(1)
N(4)-P(2)-N(3) 97.4(1)
N(1)-Ti-N(2)
N(3)-Ti-N(4)
71.2(1)
71.5(1)
N(4)-Ti(1)-N(3) 69.6(1)
N(1)-Ti(1)-N(2) 69.5(1)
C(54)-Ti-C(53) 86.5(1)
N(2)-P(1)-N(1) 96.9(1)
N(4)-P(2)-N(3) 96.9(1)
N(3)-Zr(1)-N(4) 64.7(1)
N(2)-Zr(1)-N(1) 64.8(1)
C(60)-Zr-C(53) 91.3(1)
N(1)-P(1)-N(2) 97.0(2)
N(3)-P(2)-N(4) 97.0(2)
93.34(2) Cl(1)-Ti-Cl(2) 90.84(2) Cl(1)-Zr-Cl(2)
95.7(1)
N(2)-P(1)-N(1) 95.4(1)
N(4)-P(2)-N(3) 96.0(1)
N(2)-P(1)-N(1) 94.8(1)
N(4)-P(2)-N(3) 95.5(1)
Σ
Σ
Σ
Σ
Σ
Σ
N(1)b
360.0(1)
359.9(1)
358.9(1)
351.6(2)
360.0(1)
360.0(1)
Σ
Σ
Σ
Σ
Σ
Σ
N(1)b
359.7(2)
349.6(1)
359.1(2)
350.5(1)
360.0(1)
360.0(1)
Σ
Σ
Σ
Σ
Σ
Σ
N(1)b
360.0(2)
358.4(2)
360.0(2)
359.6(2)
359.9(1)
360.0(1)
Σ
Σ
Σ
Σ
Σ
Σ
N(1)b
359.1(1)
349.8(1)
358.6(1)
349.5(1)
359.8(1)
360.0(1)
Σ
Σ
Σ
Σ
Σ
Σ
N(1)b
358.2(3)
360.0(3)
359.8(3)
360.0(3)
358.9(2)
359.8 (2)
N(2)b
N(2)b
N(2)b
N(2)b
N(2)b
N(3)b
N(3)b
N(3)b
N(3)b
N(3)b
N(4)b
N(4)b
N(4)b
N(4)b
N(4)b
P(1)N2Zrc
P(2)N2Zrc
P(1)N2Tic
P(2)N2Tic
P(1)N2Zrc
P(2)N2Zrc
P(1)N2Tic
P(2)N2Tic
P(1)N2Zrc
P(2)N2Zrc
a C(54) is site-disordered with about 15% of Cl(54) arising from an impurity in the lattice, and neither atom’s position was refined.
b Sum of the endo- and exo-cyclic bond angles about N(1), N(2), N(3), and N(4), respectively. c Sum of the angles within the PN2M rings.
Table 3. Selected Bond Lengths and Angles for Complex 4 and Cp(PN2)MX2 Complexes
4
6c7
7a
7b
8d
Bond Lengths [Å]
Zr(1)-N(1)
Zr(1)-N(2)
Zr(1)-Cl(4)
Zr(1)-Cl(2)
Zr(1)-Cl(1)
Zr(1)-Cl(3)
P(1)-N(1)
P(1)-N(2)
2.176(1) Zr(1)-N(1)
2.178(2) Zr(1)-N(2)
2.478(1) Zr(1)-Cl(1)
2.478(1) Zr(1)-Cl(2)
2.486(1) Zr(1)-C(1)
2.493(1) Zr(1)-C(2)
1.618(2) Zr(1)-C(5)
1.620(2) Zr(1)-C(3)
Zr(1)-C(4)
2.186(2) Zr(1)-N(1)
2.235(1) Zr(1)-N(1)
2.236(1) Zr(1)-N(2)
1.972(1) Zr(1)-F(2)
1.993(1) Zr(1)-F(1)
2.525(2) Zr(1)-N(3)
2.528(2) Zr(1)-C(1)
2.553(2) Zr(1)-C(2)
2.555(2) Zr(1)-C(4)
2.556(2) Zr(1)-C(5)
2.579(2) Zr(1)-C(3)
2.236(2) Zr(1)-X1A
1.610(2) P(1)-N(2)
1.637(2) P(1)-N(1)
2.198(2) Ti(1)-N(1)
2.251(2) Ti(1)-N(2)
1.987(1) Ti(1)-C(32)
1.990(1) Ti(1)-C(33)
2.483(2) Ti(1)-C(1)
2.525(2) Ti(1)-C(2)
2.527(2) Ti(1)-C(5)
2.553(2) Ti(1)-C(3)
2.556(2) Ti(1)-C(4)
2.570(2) Ti(1)-X1A
2.250(2) P(1)-N(2)
1.598(2) P(1)-N(1)
1.647(2)
2.109(1)
2.156(1)
2.159(2)
2.124(2)
2.349(2)
2.365(2)
2.37(2)
2.386(2)
2.399(2)
2.057(2)
1.603(1)
1.609(1)
2.215(1) Zr(1)-N(2)
2.450(1) Zr(1)-F(1)
2.429(1) Zr(1)-F(2)
2.471(2) Zr(1)-N(3)
2.492(2) Zr(1)-C(1)
2.502(2) Zr(1)-C(5)
2.513(2) Zr(1)-C(2)
2.535(2) Zr(1)-C(4)
1.619(1) Zr(1)-C(3)
1.616(1) Zr(1)-X1A
P(1)-N(2)
P(1)-N(1)
P(1)-N(2)
P(1)-N(1)
Bond Angles [deg]
N(1)-Zr(1)-N(2) 65.9(1) N(1)-Zr(1)-N(2) 65.1(1) N(1)-Zr(1)-N(2) 64.8(1) N(1)-Ti(1)-N(2) 68.2(1)
99.20(2) Cl(1)-Zr(1)-Cl(2) 91.8(1) N(2)-Zr(1)-N(3) 71.4(1) N(2)-Zr(1)-N(3) 71.0(1) C(33)-Ti-C(32) 85.9(1)
N(1)-Zr(1)-N(2) 69.6(1)
Cl(2)-Zr-Cl(3)
Cl(4)-Zr-Cl(1)
168.70(2) N(2)-P(1)-N(1)
95.5(1) F(1)-Zr(1)-F(2) 151.1(1) F(2)-Zr(1)-F(1) 151.4(1) N(2)-P(1)-N(1) 96.2(1)
N(2)-P(1)-N(1) 95.6(1) N(2)-P(1)-N(1) 94.6(1)
Σ
Σ
Σ
N(1)a
359.6(1)
359.8(1)
359.8(1)
Σ
Σ
Σ
N(1)a
359.8(1)
359.6(1)
359.8(1)
Σ
Σ
Σ
Σ
Σ
N(1)a
354.6(1)
358.0(1)
359.6(1)
539.3(2)
359.9(2)
Σ
Σ
Σ
Σ
Σ
N(1)a
359.2(1)
359.1(1)
359.8(1)
539.7(2)
360.0(2)
Σ
Σ
Σ
N(1)a
359.6(1)
358.5(2)
360.0(1)
N(2)a
N(2)a
N(2)a
N(2)a
N(2)a
ZrN2Pb
ZrN2Pb
ZrN2Pb
ZrN2C2
ZrN2Pb
ZrN2C2
TiN2Pb
c
c
ZrN3X1Ad
ZrN3X1Ad
a Sum of the endo- and exo-cyclic angles around N(1) and N(2), respectively. b Sum of the angles within the PN2M ring. c Sum of the
angles with the five-membered ring defined by Zr(1), N(1), C(24), C(25), and N(3). d Sum of the angles around Zr(1) involving the atoms
N(1), N(2), N(3), and the metal centroid X1A.
be noted that the differing hybridization of the exocyclic
N-R bonds could also lead to such behavior.
otherwise analogous neutral chloride complexes.
Further, the PN2 bite angle is narrowed because of
this distortion, while the remaining metrical param-
eters associated with the PN2 ligand are similar to
PN2Zr compounds first characterized by Roesky and co-
workers.6
In the case of the unique structure of 4, which
features a PN2 ligand substituted by N-TMS groups, the
structure differs somewhat from those reported earlier.6
The zirconium atom is octahedrally coordinated with
two axial and two equatorial chloride ligands. Given
that 4 is actually an “ate” complex, in which the
dimethylammonium counterion is H-bonded to one of
the axial chloride ligands,19 it is not surprising that the
Zr-N bond lengths are somewhat longer than in
The mixed ligand Cp(PN2) complexes 6b7 and 8d
feature structures similar to their bis(PN2) complexes
as far as the PN2 ligand is concerned. On average, the
M-N distances are slightly longer in the mixed com-
plexes when compared to their bis(PN2) analogues.
Similarly, the bite angles of the PN2 ligands are
somewhat narrower here compared with the corre-
(19) See Supporting Information for details of this structure.

502 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
sponding bis(PN2) complexes. The metal-Cp distances
are typical for these piano-stool complexes,20 and the
only significant distortion from the expected four-legged
piano-stool geometry is the twisting of the PN2 ligand
with respect to the plane defined by the metal centroid,
the metal, and the bisector of the MX2 angle. The
frontier orbitals in a CpMX2 fragment21 are such that
maximal π-donation from N to M is possible from an
orientation where the PN2 ligand is orthogonal to this
plane. Since the M-N bond distances do not imply
significant π-donation, it is possible that the skewed
arrangements seen reflect a low-energy barrier to rota-
tion about the M- - -P axis. Similar effects have been
noted in neutral amidinate complexes of this type.4,15
The structures of 7a and 7b deserve special comment.
A basic structural motif is common to both isomers and
which can be thought of as a quasi-octahedral geometry
with the Cp ligand occupying a single vertex, even
though this ligand is normally considered three-
coordinate. In particular, the sum of the angles about
the metal defined by the metal-centroid and the three
N atoms is 360° within experimental error (Table 3),
while the trans F atoms are distorted away from the
Cp ligand toward the less sterically encumbered PN2
ligand. The latter tridentate ligand adopts a mer
relationship with the metal in both structures and in
which both the N(1)-P(1)-N(2)-M and N(2)-C(24)-
C(25)-N(3)-M rings are planar within experimental
error (Table 3). The P(1)-N(1) and P(1)-N(2) distances
are marginally dissimilar, while the Zr-N distances
show considerable variation, and as might be expected,
the dative Zr(1)-N(3) distances are much longer than
the other two remaining Zr-N bonds. The Zr-F dis-
tances in these structures are short but are of compa-
rable length to those found in other metallocene com-
plexes bearing terminal Zr-F bonds.22
of the PN2 ligand and marginally shorter M-N bond
lengths. Overall, the structures of these complexes are
consistent with the PN2 ligand functioning as a 3e donor
with a minimal π-component to the M-N bonding, and
thus these complexes should be considered as 14- rather
than 16-electron complexes. The full details concerning
olefin polymerization and allied chemistry of this class
of compounds will reported in due course.8
Experimental Section
All reactions were conducted under an atmosphere of dry
N2. Standard techniques for the manipulation of air-sensitive
compounds were employed.23 All solvents were reagent grade
and were purified using a solvent purification system similar
to that described in the literature.24 The following chemicals
were obtained from commercial sources and used without
further purification unless otherwise noted: Ph2PCl, MeLi (1.4
M in Et2O, titrated with 1,3-diphenylacetone-p-tosylhydro-
zone25). The compounds Zr(NMe2)4,9 CpZr(NMe2)3,26 Cp*Zr-
(NMe2)3,26 Cp*ZrMe3,27 Ph2PCl3,28 C6F5-N3,29 and 3,5-(CF3)2C6H3-
30
N3 were prepared according to literature methods.
1H and 13C NMR spectra (referenced to residual protonated
solvent) were recorded on a Bruker AC 200, AM 250, or AC
300 or Varian Innova 400 MHz spectrometer. Chemical shifts
are referenced to residual undeutrated solvent. 31P NMR
spectra (referenced to external 85% H3PO4) and 19F NMR
spectra (referenced to external CFCl3) were obtained in the
solvent indicated on a Bruker AC 200 or Varian Innova 400
MHz spectrometer. IR spectra were recorded on a Bomem
MB100 FT-IR instrument. Elemental analyses were performed
by Oneida Research Services, NY.
Solid Methyllithium. An Aldrich SureSeal bottle was
opened up and the MeLi solution removed. About 90% of the
solvent was removed in vacuo, and then hexanes (50 mL) was
added to cause the precipitation of a large amount of white
solid. This process (reducing the volume and then adding
hexanes) was repeated two more times and then the slurry
1
pumped to dryness. H NMR spectroscopy showed that there
was a small amount of residual Et2O (less than 1%), but that
the only other proton source was MeLi. From later reactions
it became apparent that the solid contains only 69 mol % MeLi.
The residual solid is most likely LiCl.
Conclusions
A wide variety of bis(PN2) and mixed Cp(PN2) com-
plexes of group 4 are available by amine elimination
reactions and the corresponding PN2 ligands 2 or their
hydrochloride salts 1. The synthetic routes to these
ligands allow for considerable latitude as to the steric
and electronic nature of the substituents on N or P in
the resulting complexes. The solid-state structures of
complexes 3-8 show that they are similar to amidinate
complexes that have been characterized, the principle
differences revolving around the more obtuse bite angle
Diphenyl(benzylamino)(benzylimino)phosphorane Hy-
drochloride, 1a. In a typical reaction, Ph2PCl3 (5.00 g, 17.1
mmol) was placed in a Schlenk flask with CH2Cl2 (200 mL).
The solution was cooled to 0 °C, and the appropriate amine
was added over about 30-60 min (BzNH2 (7.49 mL, 68.6 mmol,
d ) 0.981)). During addition, a large amount of white solid
(identified as RNH3Cl) precipitated. Once the addition was
complete, the solution was refluxed overnight to ensure
complete reaction. After 12 h, the solution was filtered in the
air and the filtrate pumped to dryness. The resulting white
solid was recrystallized from CH2Cl2/hexanes. Often this did
not result in a solid but in a large quantity of oil that was
easily separated. Residual solvent can be removed by heating
overnight in vacuo to give a white crystalline solid (6.65 g,
89%). Spectral data were virtually identical with the corre-
(20) (a) Buijink, J. K.; Noltemeyer, M.; Edelmann, F. T. Z. Natur-
forsch. 1991, 46b, 1328. (b) Sootodeh, M.; Leitchweis, I.; Roesky, H.
W.; Noltemeyer, M.; Schmidt, H.-G. Chem. Ber. 1993, 126, 913. (c)
Gomez, R.; Duchateau, R.; Chernega, A. N.; Teuben, J. H.; Edelmann,
F. T.; Green, M. L. H. J. Organomet. Chem. 1995, 491, 153.
(21) Terpstra, A.; Louwen, J. N.; Oskam, A. D.; Teuben, J. H. J.
Organomet. Chem. 1984, 260, 207.
(22) Antinolo, A.; Lappert, M. F.; Singh, A.; Winterborn, D. J. W.;
Engelhardt, L. M.; Raston, C. L.; White, A. H.; Carty, A. J.; Taylor, N.
J. J. Chem. Soc., Dalton Trans. 1987, 1463. (b) Shah, S. A. A.; Dorn,
H.; Voigt, A.; Roesky, H. W.; Parisini, E.; Schmidt, H.-G.; Noltemeyer,
M. Organometallics 1996, 15, 3176. (c) Dorn, H.; Shah, S. A. A.;
Parisini, E.; Noltemeyer, M.; Schmidt, H.-G.; Roesky, H. W. Inorg.
Chem. 1996, 35, 7181. (d) Edelbach, B. L.; Rahman, A. K. F.;
Lachicotte, R. J.; Jones, W. D. Organometallics 1999, 18, 3170. (e)
Schormann, M.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. J.
Fluor. Chem. 2000, 101, 75. (f) Kraft, B. M.; Lachicotte, R. J.; Jones,
W. D. J. Am. Chem. Soc. 2001, 123, 10973. (g) Kraft, B. M.; Lachicotte,
R. J.; Jones, W. D. Organometallics 2002, 21, 727. (h) Kraft, B. M.;
Jones, W. D. J. Organomet. Chem. 2002, 658, 132.
(23) Shriver, D. F.; Drezdon, M. A. The Manipulation of Air-Sensitive
Compounds, 2nd ed.; Wiley: New York, 1986.
(24) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518.
(25) Lipton, M. F.; Sorensen, C. M.; Sadler, A. C.; Shapiro, R. H. J.
Organomet. Chem. 1980, 186, 155.
(26) Chandra, G.; Lappert, M. F. J. Chem. Soc. A 1968, 1940.
(27) Wolczanski, P. T.; Bercaw, J. E. Organometallics 1982, 1, 793.
(28) Chandrasekhar, V.; Chivers, T.; Kumaravel, S. S.; Meetsma,
A.; van de Grampel, J. C. Inorg. Chem. 1991, 30, 3402.
(29) Kanakarajan, K.; Haider, K.; Czarnik, A. W. Synthesis 1988,
566.
(30) Laitar, D. S.; Mathison, C. J. N.; Davis, W. M.; Sadighi, J. P.
Inorg. Chem. 2003, 42, 7354 (See Supporting Information).

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 503
sponding compounds reported by Garcia and Cristau.10 1H
the product was distilled through a short path distillation
apparatus (0.01 mm, 56-60 °C) to yield a clear liquid (3.30 g,
72%). 1H NMR (C6D6): δ 1.12 (overlapping dq, CH2, 4H), 0.84
(overlapping dt, CH3, JHP ) 17.3 Hz, JHH ) 7.4 Hz, 6H), 0.73
(br s, NH, 1H), 0.29 (s, SiCH3, 18H). 13C{1H} NMR (C6D6): δ
26.6 (d, PCH2CH3, JCP ) 78.2 Hz), 6.5 (d, PCH2CH3, JCP ) 3.7
Hz), 3.3 (exchange broadened s, SiMe3). 31P{1H} NMR (C6D6):
δ 20.1. A satisfactory combustion analysis was not obtained
for this compound.
NMR (CDCl3): δ 7.94-7.89 and 7.43-7.04 (br m, 21 H, C6H5
3
2
and NH), 3.97 (dd, 4H, CH2Ph, JPH ) 13 Hz, JHH ) 7 Hz).
31P NMR (CH2Cl2): δ 38.3. Anal. Calcd for C26H26PN2Cl: C,
72.13; H, 6.05; N, 6.47. Found: C, 71.57; H, 6.11; N, 6.13.
Diphenyl(p-tolylamino)(p-tolylimino)phosphorane Hy-
drochloride, 1b. A solution of p-tolylNH2 (14.7 g, 137 mmol)
in CH2Cl2 (100 mL) was added to a solution of Ph2PCl3 (10.000
g, 34.3 mmol) in CH2Cl2 (200 mL). The reaction was worked
up in a manner similar to that described above for the
preparation of 1a. This resulted in a white powder (14.22 g,
Synthesis of [(CF3)2C6H3N][(CF3)2C6H3NH]PPh2, 2e.
Diphenylphosphine (0.365 g, 1.96 mmol) was placed into a
Schlenk flask, and toluene (50 mL) was added. The mixture
was cooled to 0 °C, and the azide [(CF3)2C6H3]N3 (1.00 g, 3.92
mmol) in toluene (20 mL) was added dropwise. Little ef-
fervescence was initially observed, and only upon warming to
room temperature did the reaction became more vigorous. The
colorless mixture was stirred overnight at room temperature
and then heated to 40 °C for 1 h. The solvent was removed in
vacuo to give a white solid (0.826 g, 81%). Recrystallization
from cold toluene provided an analytically pure sample as the
3
96%). 1H NMR (CDCl3): δ 9.79 (d, 1H, NH, JPH ) 11 Hz),
8.07-7.99 and 7.52-7.27 (br m, 10H, C6H5), 7.18 and 6.69 (AB
doublets, 8H, C6H4CH3, 3JHH ) 8.0 Hz), 2.06 (s, 6 H, C6H4CH3).
31P NMR (CH2Cl2): δ 28.0. Anal. Calcd for C26H26PN2Cl: C,
72.13; H, 6.05; N, 6.47. Found: C, 72.27; H, 6.20; N, 6.18.
Diphenyl(benzylamino)(benzylimino)phosphorane, 2a.
A solution of 1a (3.00 g, 6.94 mmol) in 100 mL of dry CH2Cl2
was placed in a 500 mL Schlenk flask under N2 and cooled to
0 °C in an ice bath. A diethyl ether solution of potassium tert-
butoxide (0.79 g, 7.0 mmol) was added to the flask by cannula.
The reaction mixture was stirred for 5 min, and the volatiles
were removed under vacuum. The remaining solid was ex-
tracted with toluene. Removal of toluene from the extract
afforded a white solid, which was further purified by recrys-
tallization from toluene and hexane. Yield: 2.2 g (5.6 mmol,
1
toluene solvate. Mp: 115-119 °C. H NMR (C6D6, ambient):
δ 7.70-7.60 and 7.00-6.90 (m, 10H, Ph), 7.34 (s, 4H,
((CF3)2C6H3N))2), 7.27 (s, 2H, ((CF3)2C6H3N))2), 5.17 (s, 1H,
NH). 31P{1H} NMR (C6D6, ambient): δ -2.98. 19F NMR (C6D6,
ambient): δ -62.94 (s, 12 F). Anal. Calcd for C28H17F12N2P‚
C7H8: C, 57.23; H, 3.70; N, 3.81. Found: C, 57.63; H, 3.39; N,
3.69.
1
81%). H NMR (CDCl3): δ 7.9-7.2 (20H, aromatic protons),
4.22 (d, 4H, NCH2Ph, 3JPH ) 14.0 Hz). 13C{1H} NMR (CDCl3):
δ 132.2, 132.0, 131.2, 128.6, 127.5, 126.4 (aromatic carbons),
46.1 (NCH2Ph). 31P{1H} NMR (CH2Cl2): δ 11.4. Anal. Calcd
for C26H25PN2: C, 78.77; H, 6.36; N, 7.07. Found: C, 79.00;
H, 6.37; N, 6.86.
Synthesis of (C6F5N)(C6F5NH)PPh2, 2f. Diphenylphos-
phine (1.33 g, 7.14 mmol) was placed into a Schlenk flask, and
toluene (50 mL) was added at 0 °C. The azide C6F5N3 (3.00 g,
14.3 mmol) in toluene (30 mL) was added dropwise, and the
mixture was warmed to room temperature. The reaction was
stirred overnight, during which efferevescence ceased. The
mixture was heated to 80 °C for 2 h to give a pale yellow
solution. The solvent was then removed in vacuo, leaving
behind an off-white solid. Recrystallization of the solid from
toluene/hexane gave a white solid (2.79 g, 71%). Mp: 125-
Diphenyl(p-tolylamino)(p-tolylimino)phosphorane, 2b.
Method A. To a 500 mL Erlenmeyer flask was added 150 mL
of a CH2Cl2 solution of 1b (5.00 g, 11.6 mmol) and 100 mL of
3% KOH aqueous solution. The mixture was vigorously stirred
for 5 min, and the CH2Cl2 layer was then separated. The
aqueous layer was extracted with CH2Cl2 (2 × 50 mL). The
extract was combined and dried over anhydrous MgSO4.
Filtration and removal of CH2Cl2 in a vacuum afforded free
ligand as a white crystalline solid. Yield: 4.50 g (11.4 mmol,
98%). 1H NMR (CDCl3): δ 7.93, 7.42, 6.94 (18H, aromatic
protons), 5.31 (s, 1H, NH), 2.21 (s, 6H, NPhCH3).
Method B. Compound 1b (2.00 g, 4.6 mmol) was placed in
a Schlenk flask with KOtBu (520 mg, 4.6 mmol), ether (30 mL)
was added, and the mixture was allowed to stir for 1 h. The
resulting solution was filtered through Celite, and the filtrate
was reduced to dryness to produce a white solid (1.59 g, 87%).
1H NMR (C6D6): δ 8.01-7.93 and 7.15-6.86 (br m, 18H, C6H5
and C6H4CH3), 4.85 (br s, 1H, NH), 2.06 (s, 6H, C6H4CH3).
13C{1H} NMR (CDCl3): δ 132.7, 132.0, 131.9, 131.7, 129.7,
129.9, 128.7, 120.9 (C6H5 and C6H4CH3), 20.6 (C6H4CH3). 31P
NMR (CH2Cl2): δ 22.3. Anal. Calcd for C26H25PN2: C, 78.77;
H, 6.36; N, 7.07. Found: C, 78.62; H, 6.30; N, 6.90.
Diphenyl(trimethylsilylamino)(trimethylsilylimino)-
phosphorane, 2c. This compound was synthesized using a
literature procedure.11 Ph2PH (3.00 mL, 17.2 mmol, d ) 1.07)
and N3SiMe3 (5.00 mL, 35.8 mmol, d ) 0.868, 95%) were
refluxed overnight in a round-bottom flask with a reflux
condenser under a positive pressure of nitrogen. After 12 h
the reflux was stopped and the product was distilled through
a short path distillation apparatus (0.01 mm, 129 °C) to yield
a clear liquid (5.28 g, 85%). Spectral data agreed with
literature values. 1H NMR (C6D6): δ 7-7.75 (br m, C6H5, 10H),
1.88 (br s, NH, 1H), 0.34 (s, SiCH3, 9H), 0.18 (s, SiCH3, 9H).
31P{1H} NMR (C6D6): δ 0.06 (s).
1
128 °C. H NMR (C6D6, ambient): δ 7.90-7.70 and 7.0-6.90
(m, 10H, Ph), 4.22 (s, 1H, NH). 31P{1H} NMR (C6D6, ambi-
ent): δ 4.78 (s). 19F NMR (C6D6, ambient): δ -150.6 (s, br,
4F), -164.8 (s, br, 2F), -165.9 (s, br, 4F). 19F NMR (C7D8, -90
°C): δ -144.9 (s, br, 2F), -153.9 (s, br, 1F), -155.2 (s, br, 2F),
-162.6 (s, br, 2F), -166.0 (s, br, 1F), -172.0 (s, br, 2F). Anal.
Calcd for C24H11F10N2P: C, 52.52; H, 2.02; N, 5.10. Found: C,
52.90; H, 1.68; N, 5.12.
Synthesis of (C6F5N)(C6F5NH)PPh2‚HCl, 1f. Ligand 2f
(0.600 g, 1.09 mmol) was dissolved in toluene (50 mL) in a
Schlenk flask. The flask was cooled to 0 °C, and an HCl/ether
solution (0.30 mL, 3.8 M) was added. The reaction was warmed
to room temperature and the solvent removed in vacuo. The
resulting solid was washed with hexane (20 mL) and filtered
to give a white solid (0.611 g, 98%). 1H NMR (C6D6, ambient):
δ 11.90 (s, 2H, NHHCl), 7.91 and 6.77 (m, 10H, Ph). 31P{1H}
NMR (C6D6, ambient): δ 22.3 (s). 19F NMR (C6D6, ambient):
δ -142.6 (s, br, 4F), -156.8 (s, br, 2F), -163.8 (t, J ) 20.7 Hz,
4F). Anal. Calcd for C24H12N2PClF10: C, 49.29; H, 2.07; N, 4.79.
Found: C, 49.30; H, 2.02; N, 4.99.
[Ph2P(NCH2Ph)2]2ZrCl2, 3a. Compound 1a (5.083 g, 11.74
mmol) was slowly added to a solution of Zr(NMe2)4 (1.57 g,
5.87 mmol) in toluene (200 mL) and allowed to stir for several
hours. Partial vacuum was applied periodically throughout the
reaction to ensure that there was always a negative pressure
inside the flask. After 12 h the toluene was removed in vacuo,
and spectral data were obtained. The product was purified by
recrystallization from CH2Cl2/hexanes. In this fashion 4.95 g
1
of a white solid was obtained (88%). H NMR (C6D6): δ 7.60-
Diethyl(trimethylsilylamino)(trimethylsilylimino)-
phosphorane, 2d. Diethylphosphine (2.00 mL, 17.4 mmol, d
) 0.7862) and N3SiMe3 (5.00 mL, 35.8 mmol, d ) 0.868, 95%)
were refluxed overnight in a round-bottom flask with a reflux
condenser under a positive pressure of nitrogen. After 12 h
7.55, 7.32-7.27, and 7.15-6.87 (br m, 40H, C6H5), 4.62 (d, 8H,
CH2Ph, 3JHP ) 26 Hz). 13C NMR (CDCl3): δ 141.2, 133.2-132.0,
and 128.8-126.4 (C6H5), 51.7 (CH2Ph). 31P NMR (CH2Cl2): δ
45.8. Anal. Calcd for C52H48PN4ZrCl2: C, 65.53; H, 5.08; N,
5.88. Found: C, 65.72; H, 5.29; N, 5.81. Single crystals were

504 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
(C6D6, ambient): δ 41.0 (s). 19F NMR (C6D6, ambient):
-143.8 (d, 8F, J ) 20.7 Hz), -164.4 (t, 4F, J ) 19.8 Hz), -164.9
(t, 8F, J ) 22.6 Hz)
This amido complex (1.00 g, 0.768 mmol) was dissolved in
toluene (60 mL) in a Schlenk flask and cooled to 0 °C.
Chlorotrimethylsilane (0.21 mL, 1.65 mmol) was added, and
the reaction was warmed to room temperature and then heated
at 50 °C overnight. The solvent was removed in vacuo, and
the white residue was dissolved in toluene (50 mL) and filtered
via a Celite pad to give a pale yellow filtrate. The solvent was
removed in vacuo to ca. 20 mL and the flask placed into a -30
°C freezer to give a white solid (0.817 g, 85%).
obtained by dissolving the solid in a minimal amount of hot
toluene and allowing it to stand overnight.
δ
[Ph2P(NCH2Ph)2]2TiCl2, 3b. Ligand salt 1a (3.55 g, 8.21
mmol) was dissolved with 150 mL of dry CH2Cl2 in a 500 mL
Schlenk flask. A 50 mL toluene solution of Ti(NMe2)4 (0.918
g, 4.09 mmol) was added to the flask rapidly by syringe. The
reaction mixture was stirred for 30 min, and volatiles were
removed under vacuum. Bright yellow crystals of complex 3a
were obtained by crystallization from CH2Cl2 and hexane.
Yield: 82%. 1H NMR (CDCl3): δ 7.5-6.9 (40H, aromatic
protons), 4.65 (d, 8H, NCH2Ph, 3JPH ) 25.5 Hz). 13C{1H} NMR
(CDCl3): δ 141.0, 133.7, 133.5, 132.2, 132.2, 129.2, 128.0, 127.8,
127.5, 126.6 (aromatic carbons), 55.3 (NCH2Ph). 31P{1H} NMR
(CH2Cl2): δ 47.3. Anal. Calcd for C52H48N4P2Cl2Ti: C, 68.66;
H, 5.32; N, 6.15. Found: C, 69.05; H, 5.14; N, 6.00.
Synthesis of [Me2NH2][Ph2P(NTMS)2]ZrCl4], 4. A solu-
tion of ligand 2c (2.294 g, 6.4 mmol) in a minimal volume of
toluene was added to a solution of Zr(NMe2)4 (1.702 g, 6.4
mmol) in toluene at 25 °C with stirring. The solution turned
yellow immediately, and the flask was evacuated to remove
dimethylamine. After subsequent stirring for 48 h at 25 °C,
the solution was concentrated in vacuo to provide crude tris-
(dimethylamido) complex, sufficiently pure for further use
[Ph2P(N-p-tolyl)2]2ZrCl2, 3c. Compound 1b (7.000 g, 16.17
mmol) was slowly added to a solution of Zr(NMe2)4 (2.16 g,
8.08 mmol) in toluene (200 mL) and allowed to stir for several
hours at room temperature. The reaction was worked up as
described above for the preparation of 3a to produce a white
1
1
(3.523 g, 95%). H NMR (C6D6, 25 °C): δ 7.9-7.8 (br m, 4H,
solid (6.54 g, 85%). H NMR (CDCl3): δ 7.54-7.45 and 7.28-
3
Ph) 7.12-7.08 (m, 6 H, Ar), 3.19 (s, 18 H, NMe2), 0.04 (s, 18H,
SiMe3).
7.21 (br m, 10H, C6H5), 6.89 (d, 4H, m-C6H4CH3, JHH ) 8.2
3
3
Hz), 6.72 (dd, 4H, o-C6H4CH3, JHH ) 8.2 Hz, JPH ) 1.9 Hz),
2.28 (s, 6H, C6H4CH3). 13C NMR (CDCl3): δ 143.1, 133.6-132.2
and 129.2-125.6, and 116.4 (C6H5 and C6H4CH3), 20.8
(C6H5CH3). 31P NMR (CH2Cl2): δ 34.8. Anal. Calcd for
C52H48P2N4ZrCl2: C, 65.53; H, 5.08; N, 5.88. Found: C, 65.36;
H, 5.20; N, 5.74.
A solution of the above complex (0.300 g, 0.51 mmol) in
CH2Cl2 was stirred with an excess of Me2NH‚HCl (0.166 g,
2.04 mmol) at room temperature for a period of 12 h, during
which time all of the hydrochloride salt dissolved. The mixture
was evaporated to dryness in vacuo. This afforded a mixture
of the title compound (major) and what appears to be [Ph2P-
(NTMS)2]ZrCl3‚(Me2NH)2. Crystallization from a mixture of
CH2Cl2 and toluene provided single crystals of the title
compound, the structure of which was confirmed by X-ray
crystallography. Anal. Calcd for C20H36N3Cl4Si2PZr: C, 37.61;
H, 5.68; N, 6.58. Found: C, 37.25; H, 5.97; N, 6.23.
[Ph2P(N-p-tolyl)2]2TiCl2, 3d. Phosphonium salt 1b (3.55
g, 8.21 mmol) was dissolved with 150 mL of dry CH2Cl2 in a
500 mL Schlenk flask. A 50 mL toluene solution of Ti(NMe2)4
(0.918 g, 4.09 mmol) was added to the flask rapidly by syringe.
The reaction mixture was stirred for 30 min, and volatiles were
removed under vacuum. The remaining solid was dissolved
with 50 mL of CH2Cl2, and 100 mL of hexane was carefully
added on the top of the CH2CL2 layer. The mixture was left
undisturbed overnight, and purple crystals formed. These
crystals contained 1 equiv of CH2Cl2 solvent (as shown by NMR
and elemental analysis). The solvent-free complex 6 was
obtained by dissolving the crystals in toluene and then
removing the volatiles. Yield: 3.16 g (3.48 mmol, 85%). 1H
NMR (CDCl3): δ 7.4-6.8 (36H, aromatic protons), 2.27 (s, 12H,
NPhCH3). 13C{1H} NMR (CDCl3): δ 146.4, 134.0, 133.8, 132.8,
132.5, 128.8, 128.1, 127.9, 125.2 (aromatic carbons), 20.9
(NPhCH3). 31P{1H} NMR (CH2Cl2): δ 36.5. Anal. Calcd for
C53H50N4P2Cl4Ti: C, 64.07; H, 4.97; N, 5.64. Found: C, 64.35;
H, 4.94; N, 5.72.
Synthesis of [(C6F5N)2PPh2]2ZrCl2, 3e. Method A. Ligand
salt 1f (1.00 g, 1.71 mmol) was added in small portions to a
solution of Zr(NMe2)4 (0.229 g, 0.856 mmol) in toluene (60 mL)
at -30 °C. The reaction was warmed to room temperature and
stirred overnight to give a clear solution. The solvent was
removed in vacuo to give a white solid. The solid was stirred
with hexane (50 mL) and filtered off. Recrystallization from
toluene (20 mL) gave a white powder (0.887 g, 79%). 1H NMR
(C6D6, ambient): δ 7.72-7.62 and 7.00 (m, 20H, Ph). 31P{1H}
NMR (C6D6, ambient): δ 47.4 (s). 19F NMR (C6D6, ambient):
δ -142.6 (d, 8F, J ) 20.7 Hz), -161.2 (t, 4F, J ) 22.6 Hz),
-163.8 (t, 8F, J ) 21.7 Hz). Anal. Calcd for C48H20N4P2-
Cl2F20Zr: C, 45.87; H, 1.60; N, 4.45. Found: C, 45.50; H, 1.54;
N, 4.56.
[Ph2P(NCH2Ph)2]2ZrMe2, 5a. Complex 3a (1.50 g, 1.57
mmol) was placed in a Schlenk flask with 100 mL of toluene.
MeLi (1.908 mL, 1.65 M in ether, 3.14 mmol) was added via
syringe to the solution at room temperature over about 5 min.
The mixture was allowed to stir for 1 h, and then the solvent
was removed in vacuo. The solids were redissolved in about
10 mL of CH2Cl2 and then filtered through Celite. The flask
and Celite were washed with two additional portions of
CH2Cl2. Removal of solvent resulted in a white, crystalline
powder (1.10 g, 77%). 1H NMR (C6D6): δ 7.57-7.50 and 7.27-
3
6.93 (br m, 40H, C6H5), 4.48 (d, 8H, CH2C6H5, JPH ) 26 Hz),
1.15 (s, 6H, CH3). 13C NMR (CDCl3): δ 142.8 and 132.6-125.8
(C6H5), 49.9 (CH2Ph), 40.0 (t, ZrCH3, 3JCP ) 3.4 Hz). 31P NMR
(CH2Cl2): δ 48.0. Anal. Calcd for C54H54P2N4Zr: C, 71.10; H,
5.97; N, 6.14. Found: C, 71.05; H, 5.87; N, 5.90.
[Ph2P(NCH2Ph)2]2TiMe2, 5b. Complex 3b (1.22 g, 1.34
mmol) was dissolved with 100 mL of toluene in a 250 mL flask,
and the resulting solution was cooled to -30 °C. A solution of
MeLi in ether (1.63 mL, 1.65 M, 2.68 mmol) was added rapidly.
The reaction mixture was allowed to warm to room temper-
ature and stirred for 30 min. The remaining material was
extracted with toluene. The volume of extract was reduced to
15 mL; layering this solution with 30 mL of hexane provided
complex 5b (0.95 g, 1.10 mmol) as orange-red crystals. Yield:
82%. 1H NMR (CDCl3): δ 7.5-6.9 (40H, aromatic protons), 4.24
(d, 8H, NCH2Ph, 3JPH ) 27.1 Hz), 1.30 (s, 6H, TiCH3). 13C{1H}
NMR (CDCl3): δ 142.9, 133.2, 133.0, 131.7, 131.2, 129.9, 129.3,
128.4, 128.0, 127.9, 127.6, 125.8 (aromatic carbons), 62.7
(TiCH3), 51.7 (NCH2Ph). 31P{1H} NMR (CH2Cl2): δ 49.9. Anal.
Calcd for C54H54N4P2Ti: C, 74.64; H, 6.26; N, 6.44. Found: C,
74.24; H, 5.96; N, 6.55.
Method B. Zr(NMe2)4 (0.244 g, 0.912 mmol) was placed into
a Schlenk flask, and toluene (60 mL) was added at -30 °C.
Ligand 2f (1.00 g, 1.82 mmol) in toluene (20 mL) was added
dropwise to the solution. The mixture was warmed to room
temperature and stirred overnight to give a pale yellow
solution. The solvent was removed in vacuo to give a white
solid, which was washed with hexane (50 mL) and filtered off
to provide bis(dimethylamido) complex of sufficient purity for
[Ph2P(N-p-tolyl)2]2ZrMe2, 5c. Complex 3c (1.0 g, 1.05
mmol) was placed in a Schlenk flask with toluene (50 mL),
and MeLi (1.61 mL, 2.10 mmol) was syringed in and the
solution was allowed to stir for 1 h. After this time the toluene
was removed in vacuo and the solid was redissolved in CH2Cl2
and filtered. The solvent was removed in vacuo to give a white,
1
further use (1.04 g, 89%). H NMR (C6D6, ambient): δ 7.50-
7.40 and 7.00 (m, 20H, Ph), 2.96 (s, 12H, NMe2). 31P{1H} NMR

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 505
crystalline powder. 1H NMR (THF-d8): δ 7.61-7.08 (br m, 20H,
was reduced until a solid began to precipitate. The solution
was reduced some more (5 mL), and hexanes (100 mL) were
added to precipitate all of the material. The mixture was
filtered, and the solid was washed with 2 × 20 mL of hexanes.
The white solid was dried under vacuum (3.27 g, 77%). 1H
NMR (CDCl3): δ 7.76-7.49 (br m, 10H, C6H5), 6.90 (d, 4H,
3
C6H5), 6.76 and 6.61 (d, 16H, C6H4CH3, JHH ) 8.0 Hz), 2.19
(s, 12H, C6H4CH3), 0.30 (s, 6H, Zr-CH3). 13C NMR (CDCl3): δ
143.9 and 133.2-125.2 (C6H5 and C6H4CH3), 43.6 (t, ZrCH3,
3JCP ) 3.2 Hz), 20.7 (C6H4CH3). 31P NMR (CH2Cl2): δ 35.0.
Anal. Calcd for C54H54P2N4Zr: C, 71.10; H, 5.97; N, 6.14.
Found: C, 71.55; H, 5.85; N, 5.92.
3
m-C6H4CH3, JHH ) 8.2 Hz), 6.68 (s, 5H, C5H5), 6.61 (dd, 4H,
3
4
o-C6H4CH3, JHH ) 8.3 Hz, JHP ) 1.7 Hz), 2.22 (s, 6H,
C6H5CH3). 13C NMR (CDCl3): δ 142.9 and 133.2-124.9 (C6H5
and C6H4CH3), 116.4 (C5H5), 20.7 (C6H4CH3). 31P NMR (CH2Cl2):
δ 31.9. Anal. Calcd for C31H29PN2ZrCl2: C, 59.80; H, 4.69; N,
4.50. Found: C, 59.40; H, 4.97; N, 4.26.
[Ph2P(N-p-tolyl)2]2TiMe2, 5d. Complex 3d (1.40 g, 1.54
mmol) was dissolved with 150 mL of toluene in a 500 mL
Schlenk flask, and the resulting solution was cooled to 0 °C.
A solution of MeMgBr in ether (1.2 mL, 2.6 M, 3.1 mmol) was
added to the flask rapidly by syringe, which resulted in an
immediate color change from deep red to yellow. The reaction
mixture was allowed to stir for 30 min at 0 °C, and volatiles
were then removed under vacuum. The remaining material
was extracted with toluene. The volume of extract was reduced
to 15 mL; layering this solution with 30 mL of hexane provided
1.0 g of crystals. Yield: 75%. 1H NMR (CDCl3): δ 7.5-6.6 (36H,
aromatic protons), 2.25 (s, 6H, NPhCH3a), 2.24 (s, 6H, NPhCH3b),
1.23 (TiCH3). 13C{1H} NMR (CDCl3): δ 145.5, 133.6, 133.5,
133.4, 133.3, 131.7, 131.6, 131.4, 130.9, 130.1, 128.8, 128.0,
127.8, 125.7, 125.6 (aromatic carbons), 69.9 (TiCH3), 20.8 (N-
Ph-CH3). 31P{1H} NMR (CH2Cl2): δ 38.0. Anal. Calcd for
C54H54N4P2Ti: C, 74.64; H, 6.26; N, 6.44. Found: C, 74.40; H,
5.89; N, 5.93.
[Ph2P(N-p-tolyl)2]2Zr(CH2Ph)2, 5e. Complex 3c (2.00 g,
2.10 mmol) was placed in a Schlenk flask along with toluene
(100 mL). Powdered KCH2Ph (547 mg, 4.20 mmol) was slowly
added with stirring. The mixture was allowed to stir for 1 week
before the red color of the KCH2Ph disappeared to give a yellow
solution. The solvent was removed in vacuo, and the resulting
solid was redissolved in a small amount of toluene and filtered
through Celite. The solid and Celite are washed with two more
portions of toluene (20 mL). The filtrate volume was reduced,
and yellow, single crystals were obtained by layering the
solution with hexanes (1.243 g, 56%). 1H NMR (CDCl3): 7.41-
6.46 (br m, 46H, C6H5 and C6H4CH3), 2.41 (s, 4H, CH2Ph), 2.23
(C6H5CH3). 31P NMR (CH2Cl2): δ 36.2.
Synthesis of Cp*Zr[(p-CH3(C6H4)N)2PPh2]Cl2, 6c. A
solution of Cp*Zr(NMe2)3 (1.00 g, 2.79 mmol) was placed into
a Schlenk flask, and hexane (60 mL) was added. The solution
was cooled to -30 °C, and ligand 2b (1.11 g, 2.79 mmol) in
toluene (40 mL) was added dropwise to the flask. The reaction
was allowed to warm to room temperature and stirred over-
night to give a pale yellow solution. Next, the solvent was
removed in vacuo to give a yellow residue that was extracted
with two portions of hexane (2 × 50 mL) and passed through
Celite to give a pale yellow filtrate. The solvent was removed
in vacuo to ca. 20 mL and placed in a -30 °C freezer to give
bis(amido) complex as a pale yellow solid, sufficiently pure for
the next step (1.33 g, 67%). 1H NMR (C6D6, ambient): δ 7.92-
7.80 and 6.99 (m, 10H, Ph), 6.90 and 6.86 (d, 8H, J ) 8.2 Hz,
C6H4CH3), 3.10 (s, 12H, NMe2), 2.17 (s, 15H, Cp*), 2.10 (s, 6H,
C6H4CH3). 31P{1H} NMR (C6D6, ambient): δ 28.0 (s).
This bis(amido) complex (1.10 g, 1.55 mmol) was placed into
a Schlenk flask, and toluene (60 mL) was added flask at 0 °C.
Me3SiCl (0.41 mL, 3.23 mol) was added to the flask and the
mixture warmed to room temperature. The flask was heated
to 50 °C and stirred overnight to give a cloudy yellow solution.
The solvent was removed in vacuo, and the yellow residue was
dissolved in toluene (100 mL) and filtered via a Celite pad.
The solvent was then removed in vacuo to ca. 20 mL and an
equal volume of hexane added to give an off-white powder
(0.852 g, 79%). 1H NMR (C6D6, ambient): δ 7.76-7.67 and 6.94
(m, 10H, Ph), 6.96 and 6.82 (d, 4H, J ) 8.1 Hz, C6H4CH3),
2.17 (s, 15H, Cp*), 2.01 (s, 6H, C6H4CH3). 31P{1H} NMR (C6D6,
ambient): δ 31.5 (s). Anal. Calcd for C36H39N2PCl2Zr: C, 62.41;
H, 5.67; N, 4.04. Found: C, 62.44; H, 5.67; N, 4.18.
Cp[Ph2P(NCH2Ph)2]ZrCl2, 6a. Method A. A solution of
CpZr(NMe2)3 (1.00 g, 3.47 mmol) in toluene (50 mL) was
prepared in a Schlenk flask. Ligand 2a (1.37 g, 3.47 mmol)
was slowly added to the solution at room temperature. Vacuum
was applied to remove the dimethylamine that was liberated.
The solution was allowed to stir overnight. The next day,
Me2NH2Cl (565 mg, 6.93 mmol) was added. The solid slowly
dissolved in about 6 h, and vacuum was applied to remove the
Me2NH. After 24 h the solution was reduced almost to dryness
and then layered with hexane, producing a white solid. This
was washed twice with pentane and dried under vacuum (yield
1.764 g, 82%).
Cp[Ph2P(NSiMe3)2]ZrCl2, 6d. A solution of ligand 2c
(1.400 g, 3.88 mmol) in toluene (100 mL) was slowly added to
a solution of CpZr(NMe2)3 (1.120 g, 3.88 mmol) in toluene to
form a yellow solution. This solution was stirred for 10 min,
and then NMe2H2Cl (0.633 g, 7.77 mmol) was added and the
mixture was allowed to stir overnight until all of the solid had
dissolved. The solution became colorless overnight. The solvent
was removed in vacuo, and the resulting solid was dissolved
in about 5 mL of CH2Cl2, to which 20 mL of hexanes was
added. The volume was reduced to about 5 mL, and another
20 mL of hexanes was added. This process was repeated
several times until a large amount of white solid precipitated.
Method B. A solution of CpZr(NMe2)3 (1.50 g, 5.20 mmol)
and salt 1a (2.25 g, 5.20 mmol) in toluene (50 mL) was
prepared. This was stirred overnight. The next day, Me2NH2Cl
(424 mg, 5.20 mmol) was added and the solution was allowed
to stir overnight until the entire solid had dissolved. Partial
vacuum was applied to remove Me2NH as it was produced. A
solid was obtained by reducing the volume of the solution
almost to dryness and then adding about 100 mL of pentane.
The white solid was collected, washed with pentane, and dried
1
This gave 1.80 g (79%) of a pure (by H NMR spectroscopy)
1
white solid. H NMR (C6D6): δ 7.85-7.77 and 7.11-7.01 (br
m, 10 H, C6H5), 6.57 (s, 5H, C5H5), 0.003 (s, 18H, SiCH3). 13C
NMR (CDCl3): δ 132.6-128.4 (aromatic C), 116.3 (C5H5), 2.80
(SiCH3). 31P NMR (CH2Cl2): δ 22.2. Anal. Calcd for C23H33PN2-
Si2ZrCl2: C, 47.08; H, 5.67; N, 4.77. Found: C, 48.15; H, 5.70;
N, 4.25.
1
in vacuo (2.88 g, 90%). H NMR (CDCl3): δ 7.67-6.92 (br m,
20H, C6H5), 6.12 (s, 5H, C5H5), 4.22 (d, 4H, CH2Ph, 3JHP ) 21
Hz). 13C NMR (CDCl3): δ 140.4, 132.9-132.5, and 129.2-127.0
(C6H5), 115.5 (C5H5), 51.7 (CH2Ph). 31P NMR (CH2Cl2): δ 36.8.
Anal. Calcd for C31H29PN2ZrCl2: C, 59.80; H, 4.69; N, 4.50.
Found: C, 59.82; H, 4.95; N, 4.25.
Cp[Et2P(NSiMe3)2]ZrCl2, 6e. A solution was made of
ligand 2d (0.700 g, 2.65 mmol) and CpZr(NMe2)3 (0.764 g, 2.65
mmol) in toluene (100 mL). The yellow solution was allowed
to stir for about 10 min, and then NMe2H2Cl (0.432 g, 7.56
mmol) was added. The solution rapidly turned colorless and
was allowed to stir overnight. In the same manner as described
for the preparation of 6d, the solvent was removed under
vacuum and the resulting solid was recrystallized from CH2Cl2/
hexanes. This gave an initial batch of white, single crystals
(0.580 g), and the filtrate was further concentrated to yield
Cp[Ph2P(N-p-tolyl)2]ZrCl2, 6b. CpZr(NMe2)3 (2.00 g, 6.94
mmol) and compound 1b (3.00 g, 6.94 mmol) were placed in a
Schlenk flask along with toluene (100 mL). The solution was
allowed to stir overnight. After 12 h, Me2NH2Cl (560 mg, 6.94
mmol) was added and the solution was stirred overnight so
that the entire solid had dissolved. The volume of the solution

506 Organometallics, Vol. 24, No. 4, 2005
Vollmerhaus et al.
another 0.515 g of a pure white powder (total ) 1.095 g, 85%).
1H NMR (C6D6): δ 6.40 (s, 5H, C5H5), 1.10 (dq, 4H, CH2CH3),
0.85 (dt, 6H, CH2CH3). 13C NMR (CDCl3): δ 116.2 (C5H5), 25.2
(d, CH2CH3, JCP ) 65 Hz), 5.07 (d, CH2CH3, JCP ) 6.0 Hz),
2.70 (d, SiCH3, 3JCP ) 2.9 Hz). 31P NMR (CH2Cl2): δ 44.2. Anal.
Calcd for C15H33PN2Si2ZrCl2: C, 36.72; H, 6.78; N, 5.71.
Found: C, 36.50; H, 6.56; N, 5.54.
Synthesis of CpZr{[(CF3)2C6H3N)}2PPh2]Cl2, 6f. CpZr-
(NMe2)3 (0.451 g, 1.56 mmol) was added to a Schlenk flask
containing toluene (50 mL) at -30 °C. Ligand 2e (1.00 g, 1.56
mmol) in toluene (50 mL) was added dropwise into the reaction
flask, and the mixture was warmed to room temperature. The
mixture was stirred overnight at room temperature to give a
yellow solution. The solvent was evaporated in vacuo to ca.
20 mL and placed in a -30 °C freezer to give yellow crystals,
sufficiently pure for further use (1.05 g, 80%). 1H NMR (C6D6,
ambient): δ 7.70-7.58 and 6.94 (m, 10H, Ph), 7.33 (s, 2H,
((CF3)2C6H3N)), 7.15 (s, 4H, ((CF3)2C6H3N), 6.25 (s, 5H, Cp),
2.84 (s, 12H, NMe2). 31P{1H} NMR (C6D6, ambient): δ 33.2
(s). 19F NMR (C6D6, ambient): δ -62.9 (s, 12F, CF3).
The resulting white solid was stirred with hexane (30 mL) and
1
filtered off (0.406 g, 57%). H NMR (C6D6, ambient): δ 7.60-
7.45 and 7.05-6.85 (m, 10H, Ph), 6.47 (s, 5H, Cp). 31P{1H}
NMR (C6D6, ambient): δ 45.0 (s). 19F NMR (C6D6, ambient):
δ -142.6 (d, 4F, J ) 22.6 Hz), -159.4 (t, 2F, J ) 21.7 Hz),
-163.3 (t, 4F, J ) 22.6 Hz). Anal. Calcd for C29H15N2-
PCl2F10Zr: C, 44.97; H, 1.95; N, 3.61. Found: C, 44.64; H, 1.80;
N, 3.85.
1
2
Synthesis of CpZr{[2-(NMe2)C6F4N]2PPh2}F2, 7a, and
CpZr{(C6F5N)[2,6-(NMe2)2C6F4N]}PPh2]F2, 7b. CpZr(NMe2)3
(1.00 g, 3.47 mmol) in toluene (50 mL) was prepared in a
Schlenk flask and cooled to -30 °C. Ligand 2f (1.90 g, 3.47
mmol) in toluene (30 mL) was added dropwise, and the mixture
was warmed to room temperature to give a pale yellow
solution. The mixture was further stirred for 2 days and the
solvent then removed in vacuo. The resulting white solid was
washed with hexane (20 mL) and filtered off to give 1.79 g of
7a and 7b. The solid mixture was dissolved in toluene (50 mL)
and filtered through Celite. The filtrate was removed in vacuo
to ca. 20 mL and placed in the freezer (-30 °C) to give 1.07 g
of complex 7a as a white crystalline solid, while leaving the
mother liquor at -30 °C gave 0.408 g of complex 7b as a white
solid. Complex 7a: 1H NMR (C6D6, ambient): δ 8.15 and 7.48
and 6.98 (s, br, 10H, Ph), 6.23 (s, 5H, Cp), 3.15 and 3.04 and
2.27 (s, br, 12H, NMe2). 31P{1H} NMR (C6D6, ambient): δ 36.7
(s) 31.4 (s). 19F NMR (C6D6, ambient): δ 81.6 (d, J ) 36.6 Hz),
63.2 (d, J ) 97.7 Hz), 46.7 (d, J ) 36.6 Hz), 42.9 (d, J ) 97.7
Hz), -142.0 (s, br, 1F), -145.9 (d, 2F, J ) 24.4 Hz), -145.9 (s,
br, 1F), -150.6 (s, br, 1F), -158.8 (s, br, 1F), -159.8 (t, 1F, J
) 24.4 Hz), -161.9 (s, br, 1F), -164.0 (s, br, 1F), -171.1 (t,
1F, J ) 24.4 Hz), -171.4 (s, br, 1F). 19F NMR (C7D8, -60 °C):
δ 80.5 (d, 1F, J ) 36.6 Hz), 42.2 (d, 1F, J ) 36.6 Hz), -146.1
(d, 2F, J ) 24.4 Hz), -147.7 (d, 2F, J ) 24.4 Hz), -159.4 (t,
2F, J ) 24.4 Hz), -170.7 (br, 2F). Anal. Calcd for C33H27N4-
PF10Zr‚C7H8: C, 54.35; H, 3.99; N, 6.34. Found: C, 54.76; H,
3.87; N, 6.25. Complex 7b: 1H NMR (C6D6, ambient): δ 7.93
and 7.02 (s, br, 10H, Ph), 6.15 (s, 5H, Cp), 3.12 (s, 6H, NMe2),
1.40 (s, 6H, NMe2). 31P{1H} NMR (C6D6, ambient): δ 36.3 (s).
19F NMR (C6D6, ambient): δ 30.9 (s, 2F), -141.2 (d, 1F, J )
22.6 Hz), -144.1 (d, 1F, J ) 22.6 Hz), -144.6 (d, 2F, J ) 22.6
Hz), -160.5 (t, 1F, J ) 23.5 Hz), -164.1 (t, 2F, J ) 22.6 Hz),
-171.8 (t, 1F, J ) 20.7 Hz). Anal. Calcd for C33H27N4PF10Zr:
C, 50.06; H, 3.44; N, 7.08. Found: C, 49.70; H, 3.22; N, 6.79.
Cp[Ph2P(NCH2Ph)2]ZrMe2, 8a. Complex 6a (1.00 g, 1.61
mmol) was placed in a Schlenk flask, and THF (25 mL) was
added. The mixture was cooled to 0 °C, and MeMgBr (1.24
mL in THF, 3.22 mmol) was added rapidly via syringe. The
solution was allowed to warm to room temperature and stirred
for 10 min. Then the solution volume was reduced to about 2
mL, 25 mL of toluene was added, and the volume was reduced
again. This process was repeated about 3 or 4 times until no
more THF was seen in the 1H NMR spectrum of the crude
material. The residual solid was dissolved in a small amount
of CH2Cl2, the volume was reduced to about 1-2 mL, and
hexanes (20 mL) were added. This process was repeated 2 or
3 times to produce a white precipitate, which 1H NMR spectra
The amido complex (0.702 g, 0.794 mmol) was placed into a
Schlenk flask, and toluene (50 mL) was added at -30 °C.
Me3SiCl (0.21 mL, 1.65 mmol) was added and the yellow
mixture stirred to room temperature. After stirring overnight,
the mixture was heated to 60 °C for 2 h, resulting in a colorless
solution. The solvent was removed in vacuo to ca. 20 mL and
placed in a -30 °C freezer to give a white solid (0.522 g, 66%).
1H NMR (C6D6, ambient): δ 7.38 (s, 2H, ((CF3)2C6H3N)), 7.32
(s, 4H, ((CF3)2C6H3N), 6.97-6.91 and 6.85-6.82 (m, 10H, Ph),
6.29 (s, 5H, Cp). 31P{1H} NMR (C6D6, ambient): δ 37.0 (s). 19
F
NMR (C6D6, ambient): δ -62.9 (s, 12F, CF3). A satisfactory
combustion analysis was not obtained for this compound.
Synthesis of Cp*Zr{[(CF3)2C6H3N)]2PPh2}Cl2, 6g. Cp*Zr-
(NMe2)3 (0.920 g, 2.56 mmol) was placed into a Schlenk flask,
and toluene (50 mL) was added at -30 °C. Then ligand 2e
(1.64 g, 2.56 mmol) in toluene (20 mL) was added dropwise,
and the reaction mixture was allowed to warm to room
temperature. The mixture was stirred overnight to give a pale
yellow solution. The reaction was then warmed to 30 °C for 6
h and the solvent then removed in vacuo, leaving behind a
yellow solid. The solid was dissolved in two portions of hexane
(2 × 50 mL) and filtered via Celite to give a yellow solution.
Removal of the solvent in vacuo to ca. 20 mL and placement
into a -30 °C freezer gave a yellow solid, sufficiently pure for
1
further use (2.10 g, 86%). H NMR (C6D6, ambient): δ 7.74-
7.65 and 7.00-6.80 (m, 10H, Ph), 7.45 (s, 4H,((CF3)2C6H3N)),
7.35 (s, 2H, ((CF3)2C6H3N)), 2.88 (s, 12H, NMe2), 1.98 (s, 15H,
Cp*). 31P{1H} NMR (C6D6, ambient): δ 32.7 (s). 19F NMR (C6D6,
ambient): δ -62.6 (s, 12F, CF3)
The amido complex (0.859 g, 0.900 mmol) was placed into a
Schlenk flask, and toluene (50 mL) was added at -30 °C.
Me3SiCl (0.24 mL, 1.89 mmol) was added to the flask and the
mixture warmed to room temperature to give a pale yellow
solution. The reaction was stirred overnight and then heated
to 60 °C for 1 h. The solvent was removed in vacuo to ca. 20
mL and placed in a -30 °C freezer to give a pale yellow solid
(0.533 g, 63%). 1H NMR (C6D6, ambient): δ 7.47 (s, 4H,
((CF3)2C6H3N)), 7.36 (s, 2H, ((CF3)2C6H3N)), 6.95-6.90 and 6.82
(m, 10H, Ph), 2.02 (s, 15H, Cp*). 31P{1H} NMR (C6D6, ambi-
ent): δ 35.6 (s). 19F NMR (C6D6, ambient): δ -62.9 (s, 12F,
CF3). Anal. Calcd for C38H31N2PCl2F12Zr: C, 48.72; H, 3.33;
N, 2.99. Found: C, 48.57; H, 3.32; N, 2.99.
Synthesis of CpZr[(C6F5N)(C6F4N)PPh2]Cl2, 6h. CpZr-
(NMe2)3 (0.263 g, 0.911 mmol) in toluene (50 mL) was prepared
in a Schlenk flask and cooled to -78 °C. Ligand 2f (0.500 g,
0.911 mmol) in toluene (20 mL) was added dropwise to the
flask. After complete addition, the mixture was stirred at -78
°C for 1.5 h. Next, a HCl/ether solution (0.50 mL, 4 M) in
toluene (10 mL) was added dropwise to the flask. The reaction
was stirred at -78 °C for 0.5 h and then warmed to room
temperature, at which time the solvent was removed in vacuo.
1
showed to be pure product (0.510 g, 55%). H NMR (C6D6): δ
7.51-7.46 and 7.15-6.92 (br m, 20H, C6H5), 6.11 (s, 5H, C5H5),
3
4.24 (d, 4H, CH2Ph, JHP ) 23.5 Hz), 0.53 (s, 6H, ZrCH3). 13C
NMR (C6D6): δ 142.6, 132.6-126.5 (C6H5), 111.8 (C5H5), 50.3
(CH2Ph), 39.4 (ZrCH3). 31P NMR (CH2Cl2): δ 45.2. Anal. Calcd
for C33H35N2PZr: C, 68.12; H, 6.06; N, 4.81. Found: C, 68.29;
H, 6.06; N, 4.69.
Cp[Ph2P(NCH2Ph)2]TiMe2, 8b. CpTiCl3 (1.00 g, 4.56
mmol) was dissolved with 100 mL of toluene in a 500 mL
Schlenk flask and was cooled to -30 °C. A solution of
methyllithium in 8.5 mL of ether (1.6 M, 13.6 mmol) was added
to the flask rapidly by syringe. The reaction mixture was
stirred at -30 °C for 5 min, and then 25 mL of a toluene
solution of ligand 2a (1.80 g, 4.56 mmol) was added rapidly.
The mixture was allowed to warm to room temperature and

Group 4 Iminophosphonamide Complexes
Organometallics, Vol. 24, No. 4, 2005 507
stirred for 30 min, and then volatiles were removed under
vacuum. The remaining material was extracted with toluene.
Removal of toluene from the extract gave an orange-red
powder that was further purified by recrystallization from a
toluene/hexane mixture to give orange-red crystals. Yield:
50%. 1H NMR (CDCl3): δ 7.7-6.7 (20H, aromatic protons), 5.96
(SiCH3). 31P NMR (CH2Cl2): δ 24.8. Anal. Calcd for C25H39PN2-
Si2Zr: C, 53.00; H, 7.20; N, 5.13. Found: C, 52.86; H, 7.31; N,
4.70.
Cp[Et2P(NSiMe3)2]ZrMe2, 8f. Method A. Complex 6e
(1.00 g, 2.04 mmol) was placed in a Schlenk flask with toluene
(100 mL). Solid MeLi (130 mg, 4.08 mmol, 69% MeLi) was
added, and the mixture was stirred overnight. The solution
was pumped to dryness, and the resulting solid was dissolved
in benzene and filtered through Celite. The filtrate was
pumped to dryness to yield a white solid (0.800 g, 1.78 mmol,
87%). 1H NMR (C6D6): δ 6.25 (s, 5H, C5H5), 1.28-1.20 (m,
CH2CH3), 1.02-0.91 (m, CH2CH3), 0.43 (s, 6H, ZrCH3), 0.072
(s, 18H, SiCH3). 13C NMR: δ 112.3 (C5H5), 42.6 (ZrCH3), 25.8
(CH2CH3, 1JCP ) 65.4 Hz), 5.08 (CH2CH3, 2JCP ) 6.04 Hz), 3.28
(SiCH3). 31P NMR (CH2Cl2): δ 44.9. Anal. Calcd for C17H39PN2-
Si2Zr: C, 45.39; H, 8.74; N, 6.23. Found: C, 45.30; H, 8.81; N,
6.14.
Method B. A suspension of CpZrCl3 (1.34 g, 5.10 mmol) in
120 mL of ether was cooled to -65 °C. A solution of MeLi (10.1
mL of 1.54 M in ether, 15.6 mmol) was added to the stirred
suspension slowly via syringe over about 30 min. The mixture
was allowed to stir for 1 h and 30 min at -65 °C, during which
time it became homogeneous. Then Me3SiCl (2 mL) was added
to the reaction mixture in order to quench any excess MeLi. A
solution of ligand 2d (1.13 g, 4.29 mmol) in 50 mL of ether
was added slowly via cannula to the reaction mixture at -65
°C over a period of 15 min. The solution was allowed to warm
to 25 °C, and then ether and excess Me3SiCl were removed in
vacuo and the solid residue was taken up in 20 mL of toluene
and filtered under N2, washing with additional toluene. The
filtrate was concentrated in vacuo to ca. 5 mL, layered with
hexane, and then kept at -30 °C to provide a white crystalline
solid (1.45 g, 75%).
Synthesis of Cp*Zr{[(CF3)2C6H3N)]2PPh2}Me2, 8g. Com-
plex 6g (1.00 g, 1.07 mmol) was placed into a Schlenk flask,
and toluene (50 mL) was added at -30 °C. Solid MeLi (68.0
mg, 2.14 mmol, 69% MeLi) was added in small portions to the
flask, and the reaction was warmed to room temperature. A
pale yellow solution and a white precipitate appeared, and the
mixture was stirred overnight. The solvent was then removed
in vacuo. The residue was dissolved in two portions of hexane
(50 mL × 2) and filtered via Celite to give a pale yellow filtrate.
The solvent was then removed in vacuo to ca. 20 mL and
placed into a -30 °C freezer to give an off-white solid (0.824
g, 86%). 1H NMR (C6D6, ambient): δ 7.66-7.55 and 6.99-6.85
(m, 10H, Ph), 7.33 (s, 2H, ((CF3)2C6H3N)), 7.21 (s, 4H,
((CF3)2C6H3N)), 1.94 (s, 15H, Cp*), 0.28 (s, 6H, CH3). 31P{1H}
NMR (C6D6, ambient): δ 37.2 (s). 19F NMR (C6D6, ambient):
δ -62.9 (s, 12F, CF3). Anal. Calcd for C40H37N2PF12Zr: C,
53.63; H, 4.16; N, 3.13. Found: C, 54.02; H, 4.22; N, 3.04.
3
(s, 5H, Cp-protons), 4.04 (d, 4H, NCH2Ph, JPH ) 22.5 Hz),
0.54 (s, 6H, TiCH3). 13C{1H} NMR (CDCl3): δ 142.2, 142.1,
132.5, 132.4, 131.7, 128.6, 128.5, 128.4, 127.7, 126.2 (aromatic
carbons), 114.2 (Cp-Carbons), 60.3 (TiCH3), 50.9 (NCH2Ph).
31P{1H} NMR (CH2Cl2): δ 38.2. Anal. Calcd for C31H29N2PTi:
C, 73.47; H, 6.54; N, 5.19. Found: C, 73.68; H, 6.45; N, 5.12.
Cp[Ph2P(N-p-tolyl)2]ZrMe2, 8c. Method A. Complex 6c
(1.193 g, 1.92 mmol) was placed in a Schlenk flask with toluene
(50 mL). Solid MeLi (122 mg, 3.84 mmol, 69% MeLi) was
added, and the mixture was stirred for 2 h. The solution was
pumped to dryness, and the resulting solid was dissolved in
benzene and filtered through Celite. The filtrate was pumped
almost to dryness, layered with hexanes, and placed in the
freezer overnight to yield a light beige solid (830 mg, 73%).
1H NMR (THF-d8): δ 7.70-7.42 (br m, 10H, C6H5); 6.76 (d, 4H,
m-C6H4CH3, 3JHH ) 8.2 Hz), 6.47 (dd, 4H, o-C6H4CH3, 3JHH
)
4
8.2 Hz, JHP ) 1.7 Hz), 6.09 (s, 5H, C5H5), 2.13 (s, 6H,
C6H4CH3), 0.03, (s, 6H, ZrCH3). 13C NMR (C6D6): δ 144.8,
133.2-125.8 (C6H5 and C6H4CH3), 112.4 (C5H5), 39.8 (ZrCH3),
20.5 (C6H4CH3). 31P NMR (C6D6): δ 35.6. Anal. Calcd for
C33H35N2PZr: C, 68.12; H, 6.06; N, 4.81. Found: C, 68.37; H,
6.13; N, 4.73.
Method B. A suspension of CpZrCl3 (1.33 g, 5.07 mmol) in
120 mL of ether was cooled to -65 °C. A solution of MeLi (10.1
mL of 1.54 M in ether, 15.6 mmol) was added to the stirred
suspension slowly via syringe over about 30 min. The mixture
was allowed to stir for 1 h and 30 min at -65 °C, during which
time it became homogeneous. Then Me3SiCl (2 mL) was added
to the reaction mixture in order to quench any excess MeLi. A
solution of ligand 2b (1.70 g, 4.29 mmol) in 50 mL of ether
was added slowly via cannula to the reaction mixture at -65
°C over a period of 15 min. The solution was allowed to warm
to 25 °C, and then ether and excess Me3SiCl were removed in
vacuo and the solid residue was taken up in 20 mL of toluene
and filtered under N2, washing with additional toluene. The
filtrate was concentrated in vacuo to ca. 5 mL, layered with
an equal volume of hexane, and then kept at -30 °C to provide
a white crystalline solid (1.94 g, 78%).
Cp[Ph2P(N-p-tolyl)2]TiMe2, 8d. The same procedure de-
scribed for the preparation of 8b was followed to synthesize
8d. Yield: 1.74 g (3.23 mmol, 71%). 1H NMR (CDCl3): δ 7.8-
3
7.5 (20H, phenyl protons), 6.80 (d, 4H, JHH ) 8.2 Hz), 6.38
3
(d, 4H, JHH ) 8.3 Hz), 6.42 (s, 5H Cp-protons), 2.16 (s, 6H,
NPhCH3), 0.65 (s, 6H, TiCH3). 13C{1H} NMR (CDCl3): δ 145.1,
133.0, 132.8, 132.2, 130.8, 130.6, 129.6, 129.0, 128.6, 128.5,
124.6, 124.4 (aromatic carbons), 114.9 (Cp-carbons), 64.9
(TiCH3), 20.6 (NPhCH3). 31P{1H} NMR (CH2Cl2): δ 28.4. Anal.
Calcd for C31H29N2PTi: C, 73.47; H, 6.54; N, 5.19. Found: C,
73.64; H, 6.48; N, 5.32.
Acknowledgment. The authors would like to thank
the Natural Sciences and Engineering Research Council
of Canada, Nova Chemicals Ltd. of Calgary, Alberta,
and The University of Akron for financial support of this
work.
Cp[Ph2P(NSiMe3)2]ZrMe2, 8e. Complex 6d (1.50 g, 2.56
mmol) was placed in a Schlenk flask with toluene (100 mL).
Solid MeLi (163 mg, 5.12 mmol, 69% MeLi) was added, and
the mixture was stirred for 2 h. The solution was pumped to
dryness, and the resulting solid was dissolved in benzene and
filtered through Celite. The filtrate was pumped almost to
dryness, layered with hexanes, and placed in the freezer
Supporting Information Available: Crystallographic
information files and tables of crystallographic and refinement
data, atomic coordinates and isotropic thermal parameters,
bond lengths and angles, anisotropic thermal parameters, and
H atom coordinates and thermal parameters for complexes
3a,b, 4, 5b, 5e, 7a, 7b, and 8d. This information is available
free of charge via the Internet at http://pubs.acs.org.
1
overnight to yield a white solid (1.21 g, 2.21 mmol, 86%). H
NMR (C6D6): δ 7.94-7.87 and 7.15-7.08 (br m, 10H, C6H5),
5.42 (s, 5H, C5H5), 0.63 (s, 6H, ZrCH3), -0.12 (s, 18H, SiCH3).
13C NMR (C6D6): δ 132.1, 131.9, and 131.7 (C6H5) (other half
of signals buried under C6D6), 112.4 (C5H5), 44.3 (ZrCH3), 3.35
OM0492350