Synthesis of zirconium complexes that contain the diamidophosphine ligands [(Me3SiNCH2CH2)2PPh]2- or [(RNSiMe2CH2)2PPh]2- (R = t-Bu or 2,6-Me2C6H3)

Article abstract of DOI:10.1021/om9807654

A new synthesis of PhP(CH₂CH₂NH₃Cl)₂ is reported that involves the addition of 2 equiv of butyllithium to a mixture of PhPH₂ and 2 equiv of ClCH₂CH₂(cyclo-NSiMe₂CH₂CH ₂SiMe₂). The reaction between PhP(CH₂CH₂NH₃Cl)₂ and 4 equiv of butyllithium followed by 2 equiv of Me₃SiCl then yielded (Me₃SiNHCH₂CH₂)₂PPh (H₂[N₂P]) quantitatively. Addition of H₂-[N₂P] to Zr(NMe₂)₄ in pentane gave intermediate [N₂P]Zr(NMe₂)₂ that was converted without purification to white, crystalline [N₂P]ZrCl₂ in 80% yield overall upon treatment with 2 equiv of Me₃SiCl. The alkyl complexes that were prepared include [N₂P]Zr(THF)MeCl, [N₂P]Zr-(i-Bu)Cl, [N₂P]ZrMe₂, [N₂P]Zr(CH₂Ph)₂, and [N₂P]Zr(CH₃)(CH₂Ph). An X-ray diffraction study showed that the basic structure of [N₂P]Zr(CH₃)(CH₂Ph) is a distorted trigonal bipyramid in which the methyl group is in the apical position trans to phosphorus and the η²-benzyl group is cis to phosphorus. Compounds of the type PhP(CH₂SiMe₂NHR)₂ (R = t-Bu or 2,6-Me₂C₆H₃; H₂[R₂NPN]) were prepared by treating ClCH₂SiMe₂Cl with LiNHR to give ClCH₂-SiMe₂NHR followed by a reaction between PhPH₂, ClCH₂SiMe₂NHR, and butyllithium. Zirconium complexes that were prepared include [t-Bu₂NPN]ZrMeCl, [Ar₂NPN]ZrMeCl, and [Ar₂NPN]ZrMe₂. An attempted synthesis of [t-Bu₂NPN]ZrMe₂ led to loss of a feri-butyl group and formation of a dimeric complex containing imido-type bridging nitrogen ligands, as confirmed in an X-ray study. X-ray studies of [t-Bu₂NPN]ZrMeCl and [Ar₂NPN]ZrMeCl demonstrate that extensive steric crowding exerted by a tert-butyl group in complexes of this type contributes to the inability to form a simple complex such as [PhP(CH₂SiMe₂N-t-Bu)₂]ZrMe₂.

Full text of DOI:10.1021/om9807654

428
Organometallics 1999, 18, 428-437
Syn th esis of Zir con iu m Com p lexes Th a t Con ta in th e
Dia m id op h osp h in e Liga n d s [(Me3SiNCH2CH2)2P P h ]2- or
[(RNSiMe2CH2)2P P h ]2- (R ) t-Bu or 2,6-Me2C6H3)
Richard R. Schrock,* Scott W. Seidel, Yann Schrodi, and William M. Davis
Department of Chemistry, Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139
Received September 14, 1998
A new synthesis of PhP(CH2CH2NH3Cl)2 is reported that involves the addition of 2 equiv
of butyllithium to a mixture of PhPH2 and 2 equiv of ClCH2CH2(cyclo-NSiMe2CH2CH2SiMe2).
The reaction between PhP(CH2CH2NH3Cl)2 and 4 equiv of butyllithium followed by 2 equiv
of Me3SiCl then yielded (Me3SiNHCH2CH2)2PPh (H2[N2P]) quantitatively. Addition of H2-
[N2P] to Zr(NMe2)4 in pentane gave intermediate [N2P]Zr(NMe2)2 that was converted without
purification to white, crystalline [N2P]ZrCl2 in 80% yield overall upon treatment with 2 equiv
of Me3SiCl. The alkyl complexes that were prepared include [N2P]Zr(THF)MeCl, [N2P]Zr-
(i-Bu)Cl, [N2P]ZrMe2, [N2P]Zr(CH2Ph)2, and [N2P]Zr(CH3)(CH2Ph). An X-ray diffraction study
showed that the basic structure of [N2P]Zr(CH3)(CH2Ph) is a distorted trigonal bipyramid
in which the methyl group is in the apical position trans to phosphorus and the η2-benzyl
group is cis to phosphorus. Compounds of the type PhP(CH2SiMe2NHR)2 (R ) t-Bu or 2,6-
Me2C6H3; H2[R2NPN]) were prepared by treating ClCH2SiMe2Cl with LiNHR to give ClCH2-
SiMe2NHR followed by a reaction between PhPH2, ClCH2SiMe2NHR, and butyllithium.
Zirconium complexes that were prepared include [t-Bu2NPN]ZrMeCl, [Ar2NPN]ZrMeCl, and
[Ar2NPN]ZrMe2. An attempted synthesis of [t-Bu2NPN]ZrMe2 led to loss of a tert-butyl group
and formation of a dimeric complex containing imido-type bridging nitrogen ligands, as
confirmed in an X-ray study. X-ray studies of [t-Bu2NPN]ZrMeCl and [Ar2NPN]ZrMeCl
demonstrate that extensive steric crowding exerted by a tert-butyl group in complexes of
this type contributes to the inability to form a simple complex such as [PhP(CH2SiMe2N-t-
Bu)2]ZrMe2.
In tr od u ction
Multidentate ligands of this type that have a central
donor atom, which is the more common type, and “arms”
that contain two atoms between the donor and the
amido nitrogen atom have considerable potential as
ligands in organometallic chemistry. An example is the
[(t-BuN-o-C6H4)2O]2- ([NON]2-) ligand, zirconium com-
plexes of which have been found to be catalysts for the
living polymerization of 1-hexene.5,6 Diamido/donor
ligands that contain nitrogen as the central donor in-
clude [(Me3SiNCH2CH2)2NSiMe3]2- 1-4 and [(C6F5NCH2-
Several types of “diamido/donor” ligands have been
synthesized in the last several years and employed in
the synthesis of early transition metal complexes.1-15
(1) Cloke, F. G. N.; Hitchcock, P. B.; Love, J . B. J . Chem. Soc., Dalton
Trans. 1995, 25.
(2) Clark, H. C. S.; Cloke, F. G. N.; Hitchcock, P. B.; Love, J . B.;
Wainwright, A. P. J . Organomet. Chem. 1995, 501, 333.
(3) Horton, A. D.; de With, J .; van der Linden, A. J .; van de Weg, H.
Organometallics 1996, 15, 2672.
(4) Horton, A. D.; de With, J . Chem. Commun. 1996, 1375.
(5) Baumann, R.; Schrock, R. R.; Davis, W. M. J . Am. Chem. Soc.
1997, 119, 3830.
CH2)2NH]2- 8
. One of the issues surrounding group 4
(6) Baumann, R.; Schrock, R. R. J . Organomet. Chem. 1998, 557,
69.
(7) Schrock, R. R.; Schattenmann, F.; Aizenberg, M.; Davis, W. M.
Chem. Commun. 1998, 199.
(8) Schrock, R. R.; Lee, J .; Liang, L.-C.; Davis, W. M. Inorg. Chim.
Acta 1998, 270, 353.
(9) Schattenmann, F.; Schrock, R. R.; Davis, W. M. Organometallics
1998, 17, 989.
(10) Friedrich, S.; Schubart, M.; Gade, L. H.; Scowen, I. J .; Edwards,
A. J .; McPartlin, M. Chem. Ber. Rec. 1997, 130, 1751.
(11) Gue´rin, F.; McConville, D. H.; Vittal, J . J . Organometallics
1995, 14, 3154.
(12) Gue´rin, F.; McConville, D. H.; Payne, N. C. Organometallics
1996, 15, 5085.
(13) Gue´rin, F.; McConville, D. H.; Vittal, J . J . Organometallics
1996, 15, 5586.
(14) Male, N. A. H.; Thornton-Pett, M.; Bochmann, M. J . Chem. Soc.,
Dalton Trans. 1997, 2487.
(15) Aizenberg, M.; Turculet, L.; Davis, W. M.; Schattenmann, F.
S.; Schrock, R. R. Organometallics 1998, 17, 4795.
complexes that contain diamido/donor ligands is whether
the geometries of five-coordinate dialkyl complexes (mer
and fac being the ideal limiting geometries where D )
donor) can be correlated with the degree of living
character of cationic pseudotetrahedral catalysts in the
10.1021/om9807654 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/24/1998

Zr Complexes Containing Diamidophosphine Ligands
Organometallics, Vol. 18, No. 3, 1999 429
polymerization of ethylene and terminal olefins. Con-
sequently we became interested in attempting to force
the geometry of a five-coordinate species to be fac by
employing phosphorus as the donor. No complex that
contains a simple diamido/phosphine ligand has been
reported, even though PhP(CH2CH2NH3Cl)2, the pre-
cursor to PhP(CH2CH2NH2)2 and possible PhP(CH2CH2-
NHR)2 species, was prepared over 30 years ago.16
Ligands that are most closely related to [R′P(CH2CH2-
NR)2]2- ligands include aminodiphosphine ligands17,18
such as (Ph2PCH2SiMe2)2NH and a related macrocyclic
dianionic diamidodiphosphine ligand, [N(SiMe2CH2P(Ph)-
Addition of H2[N2P] to Zr(NMe2)4 in pentane gave
intermediate [N2P]Zr(NMe2)2 as an oil that was con-
verted without purification to white, crystalline [N2P]-
ZrCl2 in 80% yield overall upon treatment with 2 equiv
of Me3SiCl (eq 3). In crude [N2P]Zr(NMe2)2 methyl
resonances for the two amido groups (each with equiva-
lent methyl groups on the NMR time scale) are found
at 3.13 and 3.05 ppm in the proton NMR spectrum, and
the molecule contains a plane of symmetry. The phos-
CH2SiMe2)2N]2- 19
We report here the synthesis of two
.
types of diamido/phosphine ligands, [PhP(CH2CH2N-
SiMe3)2]2- ([N2P]2-) and [PhP(CH2SiMe2NR)2]2- (R )
t-Bu or R ) 2,6-Me2C6H3 ) Ar; [R2NPN]2-) and several
zirconium complexes that contain them.20
Resu lts a n d Discu ssion
Th e [P h P (CH2CH2NSiMe3)2]2- Liga n d a n d [N2P ]-
Zr Com p lexes. We decided to construct the first ligand
from the known molecule,16 PhP(CH2CH2NH3Cl)2. The
synthesis of PhP(CH2CH2NH3Cl)2 that is reported in the
literature (in 23% yield) consists of the treatment of
ClCH2CH2NH2 with NaP(Ph)CH2CH2NH2 in liquid am-
monia. We believe a more convenient preparation is that
shown in eq 1. This synthesis is related to that employed
phorus resonance is found at -10.5 ppm in the 31P NMR
spectrum. NMR data for [N2P]ZrCl2 are also consistent
with a structure that has mirror symmetry; the phos-
phorus resonance is found in the 31P NMR spectrum at
1.94 ppm. On the basis of X-ray studies of related
species reported below we presume that both molecules
have fac geometries (eq 3). However, we cannot discount
the possibility that [N2P]ZrCl2 is a mirror symmetric
dimer (in the solid state) that has two pseudooctahedral
zirconium centers connected by two bridging chlorides
and the phosphorus donors on opposite sides of the Zr2-
(µ-Cl)2 ring.
Monoalkyl complexes can be prepared by monoalkyl-
ation of [N2P]ZrCl2 (eq 4). When MeMgCl (in THF) is
added to [N2P]ZrCl2 in ether, [N2P]Zr(THF)MeCl is
obtained in ∼40% yield as pentane-soluble white crys-
tals. The proton NMR spectrum revealed a doublet
by Fryzuk to prepare (Ph2PCH2SiMe2)2NH and HN-
(SiMe2CH2P(Ph)CH2CH2)2NH.19 This approach avoids
making and handling phosphides and liquid ammonia
as a solvent, and yields are essentially quantitative. The
product is obtained as a light yellow oil on a large scale
(∼50 g). PhP(CH2CH2NH3Cl)2 is obtained by treating
PhP[CH2CH2(cyclo-NSiMe2CH2CH2SiMe2)]2 in ether with
aqueous HCl.
[N2P]ZrCl2 monoalkylation8
[N2P]ZrRCl
(4)
The easiest amido derivatives to prepare are those
that contain trimethylsilyl groups. The reaction between
PhP(CH2CH2NH3Cl)2 and 4 equiv of butyllithium fol-
lowed by 2 equiv of Me3SiCl yielded (Me3SiNHCH2-
CH2)2PPh essentially quantitatively (eq 2). A white,
pentane-soluble, crystalline dilithium salt, Li2[N2P]
([N2P]2- ) [(Me3SiNCH2CH2)2PPh]2-), could be pre-
pared in moderate yield by treating (Me3SiNHCH2-
CH2)2PPh with 2 equiv of butyllithium.
R ) CH3, CH2CHMe2
2
resonance for the methyl group at 0.84 ppm with J HP
) 7 Hz. As we will show later, a PH coupling on the
order of 7 Hz is indicative of the methyl group being in
a position cis to the phosphine. A complex that does not
contain THF could be prepared by employing Me2Mg
in ether. However, several attempts to obtain satisfac-
tory analytical data for [N2P]ZrMeCl failed, even though
NMR spectra were unambiguous. Proton NMR spectra
of [N2P]ZrMeCl revealed a singlet resonance for the
methyl group at 0.9 ppm (undetectable J HP), which on
the basis of data presented below we believe to be
characteristic of a methyl group trans to the phosphorus
donor. This molecule could be a dimer with a pseudooc-
tahedral arrangement about each Zr and two bridging
chlorides. The analogous isobutyl complex, [N2P]Zr(i-
(16) Issleib, K.; Oehme, H. Chem. Ber. 1967, 100, 2685.
(17) Fryzuk, M. D.; Gao, X. L.; J oshi, K.; Macneil, P. A.; Massey, R.
L. J . Am. Chem. Soc. 1993, 115, 10581-10590.
(18) Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J . Organometallics
1992, 11, 2967-2969.
(19) Fryzuk, M. D.; Love, J . B.; Rettig, S. J .; Young, V. G. Science
1997, 275, 1445.
(20) In a private communication M. Fryzuk revealed to the principal
author that a preliminary communication describing the synthesis of
tantalum complexes that contains [PhP(CH2SiMe2NPh)2]2- had been
accepted; it has now appeared (Fryzuk, M. D.; J ohnson, S. A.; Rettig,
S. J . J . Am. Chem. Soc. 1998, 120, 11024).

430 Organometallics, Vol. 18, No. 3, 1999
Schrock et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta , Collection P a r a m eter s, a n d Refin em en t P a r a m eter s for
[N2P ]Zr (CH3)(CH2P h ), [t-Bu 2NP N]Zr (CH3)Cl, [Ar 2NP N]Zr (CH3)Cl, a n d
{[t-Bu NSiMe2CH2P (P h )CH2SiMe2N]Zr (CH3)}2 (“Dim er ”)
[N2P]Zr(CH3)(CH2Ph)
[t-Bu2NPN]Zr(CH3)Cl
[Ar2NPN]Zr(CH3)Cl
Dimer
empirical formula
fw
C
24H41N2PSi2Zr
C21H42ClN2PSi2Zr
536.39
C29H42ClN2PSi2Zr
632.47
C34H66N4P2Si4Zr2
887.65
535.96
cryst dimens (mm)
0.26 × 0.12 × 0.08
monoclinic
13.677(3)
11.936(3)
17.646(3)
90
96.182(14)
90
2863.9(11)
P21/c
0.49 × 0.35 × 0.28
orthorhombic
11.12570(10)
13.331
18.2853(3)
90
0.35 × 0.33 × 0.23
monoclinic
17.201(4)
18.766(4)
20.187(5)
90
90
90
6516(3)
P2/c
8
0.25 × 0.20 × 0.08
cryst syst
a (Å)
b (Å)
c (Å)
triclinic
10.8271(4)
11.6428(4)
19.1805(7)
97.9570(10)
92.1900(10)
111.7450(10)
2213.63(14)
P1h
R
â (deg)
γ
90
90
V (Å3)
space group
Z
2712.02(5)
P212121
4
1.314
0.661
4
2
F
calc (Mg/m3)
1.243
0.536
1128
1.289
0.562
2640
1.332
0.679
928
abs coeff (mm-1
F000
)
1128
temp (K)
183(2)
183(2)
153(2)
163(2)
θ range for data collection (deg)
no. of reflns collected
no. of ind reflns
1.50-23.26
1.89-23.26
1.90-23.26
1.91-23.26
8939
11176
11580
9111
3928
3888
3546
6223
R [I > 2σ(I)]
0.0450
0.0912
1.164
0.0175
0.0476
1.084
0.0606
0.1600
1.140
0.0522
0.1173
1.105
R
w [I > 2σ(I)]
GoF
extinction coeff
0.0016 (3)
0.373 and -0.332
0.0094(4)
0.270 and -0.263
0.0021(3)
0.825 and -0.399
0.0023
1.279 and -0.833
largest diff peak and hole (e Å-3
)
3
2
Bu)Cl, was also prepared in good yield and analyzed
satisfactorily. In this case J HP (7.7 Hz) for the isobutyl
methylene group was more consistent with the isobutyl
group being in a position cis to the phosphorus in a
monomeric, five-coordinate fac species.
value for J HP (∼10 Hz) and the smaller value for J CP
(∼5 Hz), while the methyl ligand has a small (unobserv-
3
2
able) J HP and the larger value for J CP (28 Hz).
An X-ray diffraction study (Tables 1 and 2) verified
that the basic structure of [N2P]Zr(CH3)(CH2Ph) is a
distorted trigonal bipyramid, that the methyl group is
in the apical position trans to phosphorus, and that the
benzyl ligand is in the “equatorial” position and bound
in an η2 manner (Figure 1). Therefore we can conclude
Dialkyl complexes can be prepared by dialkylation of
[N2P]ZrCl2 (eq 5). Addition of 2 equiv of MeMgCl to
[N2P]ZrCl2 dialkylation8
[N2P]Zr(R1)(R2)
(5)
2
that the large value for J CP and small (undetectable)
R1 ) R2 ) CH3, CH2Ph;
R1 ) CH3, R2 ) CH2Ph
3
value for J HP are associated with the alkyl group trans
to the phosphine donor (methyl), while the small value
2
3
for J CP and a large value for J HP are associated with
the alkyl group cis to the phosphine donor (benzyl). The
Zr-C(41) distance (2.835(4) Å) and Zr-C(47)-C(41)
angle (95.4(2)°) are similar to distances and angles in
several other recently characterized η2-benzyl complexes
of zirconium,21-25 while the Zr-P distance (2.9343(11)
Å) is somewhat longer than what has been observed
(typically 2.75-2.85 Å) in a variety of zirconium phos-
phine complexes.19,26-43 The Zr-Namido bond lengths also
[N2P]ZrCl2 yielded [N2P]ZrMe2 in high yield. Although
NMR data suggest that this complex is quite pure, it
resisted crystallization and therefore could not be puri-
fied and analyzed. [N2P]Zr(13CH3)2 was prepared simi-
larly. Proton NMR spectra of [N2P]ZrMe2 reveal a
doublet resonance at 0.80 ppm for one methyl group
(2J HP ) 6 Hz) and a singlet resonance at 0.60 ppm for
the other methyl group with no detectable coupling of
the methyl protons to phosphorus. Carbon NMR data
reveal methyl resonances with dramatically different
2J CP values at 35.9 (2J CP ) 29 Hz) and 40.9 ppm (2J CP
) 2 Hz). An analogous [N2P]Zr(CH2Ph)2 complex could
be prepared similarly and analyzed satisfactorily. Pro-
ton NMR data reveal benzyl methylene resonances at
2.75 ppm (J HP ) 6.6 Hz) and 2.69 ppm (J HP ) 2.4 Hz),
while the methylene carbon atom resonances in the
carbon NMR spectrum of [N2P]Zr(CH2Ph)2 are found at
(21) Latesky, S. L.; McMullen, A. K.; Niccolai, G. P.; Rothwell, I. P.
Organometallics 1985, 4, 902.
(22) Cloke, F. G. N.; Geldbach, T. J .; Hitchcock, P. B.; Love, J . B. J .
Organomet. Chem. 1996, 506, 343-345.
(23) Ciruelo, G.; Cuenca, T.; Gomez, R.; Gomez-Sal, P.; Martin, A.;
Rodriguez, G.; Royo, P. J . Organomet. Chem. 1997, 547, 287-296.
(24) Bei, X. H.; Swenson, D. C.; J ordan, R. F. Organometallics 1997,
16, 3282-3302.
(25) Cloke, F. G. N.; Geldbach, T. J .; Hitchcock, P. B.; Love, J . B. J .
Organomet. Chem. 1996, 506, 343.
(26) Fryzuk, M. D.; Mao, S. S. H.; Zaworotko, M. J .; MacGillivray,
L. R. J . Am. Chem. Soc. 1993, 115, 5336.
1
69.3 ppm (2J CP ) 3.2 Hz, J CH ) 126 Hz) and 65.9 ppm
(2J CP ) 22 Hz, 1J CH ) 118 Hz). Finally, [N2P]Zr(13CH3)-
(CH2Ph) could be prepared and isolated in good yield
by treating [N2P]ZrCl2 first with 13CH3MgI and then
with PhCH2MgCl. The proton and carbon CH2 reso-
nances for the benzyl ligand were found at 2.82 ppm
(3J HP ) 9 Hz) and 62.4 ppm (2J CP ) 4.6 Hz), respectively,
while for the methyl group they were found at 0.59 ppm
(undetectable J HP) and 38.2 ppm (2J CP ) 27.9 Hz),
respectively. Therefore the benzyl ligand has the larger
(27) Fryzuk, M. D.; Haddad, T. S.; Mylvaganam, M.; McConville,
D. H.; Rettig, S. J . J . Am. Chem. Soc. 1993, 115, 2782.
(28) Wengrovius, J . H.; Schrock, R. R.; Day, C. S. Inorg. Chem. 1981,
20, 1844.
(29) Waldman, T. E.; Rheingold, A. L.; Ernst, R. D. J . Organomet.
Chem. 1995, 503, 29-33.
(30) Waldman, T. E.; Stahl, L.; Wilson, D. R.; Arif, A. M.; Hutch-
inson, J . P.; Ernst, R. D. Organometallics 1993, 12, 1543-1552.
(31) Gozum, J . E.; Girolami, G. S. J . Am. Chem. Soc. 1991, 113,
3829-3837.
(32) Gozum, J . E.; Wilson, S. R.; Girolami, G. S. J . Am. Chem. Soc.
1992, 114, 9483-9492.

Zr Complexes Containing Diamidophosphine Ligands
Organometallics, Vol. 18, No. 3, 1999 431
Ta ble 2. Selected Dista n ces a n d An gles in [N2P ]Zr (CH3)(CH2P h ), [t-Bu 2NP N]Zr (CH3)Cl, [Ar 2NP N]Zr (CH3)Cl,
a n d {[t-Bu NSiMe2CH2P (P h )CH2SiMe2N]Zr (CH3)}2 (“Dim er ”)
[N2P]Zr(CH3)(CH2Ph)
[t-Bu2NPN]Zr(CH3)Cl
[Ar2NPN]Zr(CH3)Cl
Dimer (Zr(1))
Dimer (Zr(2))
Zr-Lax
2.294(4)
2.295(4)
2.054(3)
2.062(3)
2.9343(1)
109.96(14)
105.1(2)
96.5(2)
174.65(12)
102.35(13)
114.25(14)
72.89(9)
127.56(13)
69.70(8)
106.7(2)
144.66(13)
139.6
2.5067(6)
2.278(2)
2.093(2)
2.116(2)
2.6797(6)
133.09(5)
95.87(5)
84.57(6)
146.37(2)
112.41(7)
105.29(8)
79.81(5)
126.00(8)
71.94(5)
106.99(11)
125.07(8)
147.5
2.715(3)
2.343(8)
2.093(5)
2.110(5)
2.916(2)
105.1(2)
105.0(2)
93.8(2)
179.44(6)
122.3(2)
109.1(2)
74.9(2)
116.6(2)
74.6(2)
106.3(3)
128.8(3)
178.2
2.098(5)
2.282(6)
2.101(5)
2.126(4)
2.820(2)
82.2(2)
116.9(2)
101.3(2)
154.67(13)
116.2(2)
120.5(2)
73.29(13)
114.2(2)
80.59(13)
105.1(3)
133.0(2)
173.1
2.112(5)
2.272(6)
2.113(5)
2.139(5)
2.774(2)
81.6(2)
117.7(2)
102.1(2)
154.53(13)
117.4(2)
120.0(2)
73.64(13)
113.0(2)
79.85(13)
104.2(3)
129.8(2)
172.6
Zr-Leq
Zr-N(1)
Zr-N(2)
Zr-P
Lax-Zr-N(1)
Lax-Zr-N(2)
Lax-Zr-Leq
Lax-Zr-P
N(1)-Zr-N(2)
N(1)-Zr-Leq
N(1)-Zr-P
N(2)-Zr-Leq
N(2)-Zr-P
C-P-C
Zr-P-Cipso
P-Zr-N(1)-X
P-Zr-N(2)-X
Zr-N(1)-X
Zr-N(2)-X
N(1),Zr,P,N(2) planes
“arm lengths”
Zr-C(47)-C(41)
Zr-C(41)
144.7
148.9
151.9
155.4
116.2(4)
96.5(2)
121
7.573, 7.550
153.9
116.3(4)
96.6(2)
123
7.555, 7.568
125.0(2)
122.6(2)
111
6.912, 6.921
95.4(2)
116.02(13)
121.08(14)
118
108.6(4)
113.4(5)
130
7.553, 7.567
7.546, 7.574
2.835(4)
N(1) plane, with the sum of the angles at the “equato-
rial” ligands (N(1), N(2), and C(47)) being 344°. How-
ever, the C(47)-Zr-N(2) angle (127.56(13)°) is the
largest of the three, presumably in order to accom-
modate the η2-benzyl ligand that points toward N(2).
The sum of the angles around N(1) (360.0°) and N(2)
(359.8°) suggests that the amido nitrogen atoms are
strictly planar, as is the case in all compounds whose
structures are reported here. However, the TMS groups
are “tipped” from a “vertical” position (with P-Zr-N-
Si dihedral angles ) 139.6° and 144.7°), presumably in
order to avoid interacting with C(5), the consequence
of which is an “envelope” configuration in the PC2NZr
five-membered rings. The TMS group containing Si(2)
points between the two imido nitrogen atoms (away
from the η2 benzyl ligand), and Si(1) points away from
Si(2). The Zr-N-Si angles (125.0(2)° and 122.6(2)°) are
approximately the same as those observed in a wide
variety of triamidoamine complexes (∼125°).47 A con-
venient measure of the trigonal nature of the equatorial
ligand set is the angle between the N(1)/Zr/P and N(2)/
Zr/P planes, which here is 111°. This angle and the
N(1)-Zr-N(2) angle are the smallest of any correspond-
ing angles in related complexes reported here, we
presume in response to the steric demands of the η2-
benzyl ligand and formation of what could be called a
pseudo six-coordinate geometry.
F igu r e 1. ORTEP drawing of the structure of [(Me3-
SiNCH2CH2)2P]Zr(CH3)(CH2Ph).
are typical of those in related diamido compounds in
the literature, which usually fall in the range 2.05-2.12
Å.1,5,13,15,44-46 The Zr is situated above the C(47)-N(2)-
(33) Fryzuk, M. D.; Love, J . B.; Rettig, S. J . Organometallics 1998,
17, 846-853.
(34) Fryzuk, M. D.; Mao, S. S. H.; Duval, P. B.; Rettig, S. J .
Polyhedron 1995, 14, 11-23.
(35) Fryzuk, M. D.; Haddad, T. S.; Mylvaganam, M.; McConville,
D. H.; Rettig, S. J . J . Am. Chem. Soc. 1993, 115, 2782-2792.
(36) Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J . J . Am. Chem. Soc.
1990, 112, 8185-8186.
We were especially interested in whether [N2P]ZrMe2
could be activated to yield a “cation” (in the presence of
a “weakly coordinating” anion) that would be active for
polymerization of terminal olefins.48,49 [N2P]Zr(13CH3)2
reacts with [Ph3C][B(C6F5)4] in bromobenzene-d5 at -30
(37) Cotton, F. A.; Lu, J .; Shang, M. Y.; Wojtczak, W. A. J . Am.
Chem. Soc. 1994, 116, 4364-4369.
(38) Cotton, F. A.; Kibala, P. A.; Shang, M. Y.; Wojtczak, W. A.
Organometallics 1991, 10, 2626-2630.
(39) Cotton, F. A.; Shang, M. Y.; Wojtczak, W. A. Inorg. Chem. 1991,
30, 3670-3675.
(44) Scollard, J . D.; McConville, D. H.; Vittal, J . J . Organometallics
1995, 14, 5478.
(45) Warren, T. H.; Schrock, R. R.; Davis, W. M. Organometallics
1998, 17, 308.
(40) Chen, L. F.; Cotton, F. A. Inorg. Chim. Acta 1997, 257, 105-
120.
(41) Chen, L. F.; Cotton, F. A.; Wojtczak, W. A. Inorg. Chem. 1996,
35, 2988-2994.
(46) Aoyagi, K.; Gantzel, P. K.; Kalai, K.; Tilley, T. D. Organome-
tallics 1996, 15, 923.
(47) Schrock, R. R. Acc. Chem. Res. 1997, 30, 9.
(48) Brintzinger, H. H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143.
(49) Kaminsky, W.; Ardnt, M. Adv. Polym. Sci. 1997, 127, 144.
(42) Bosch, B. E.; Erker, G.; Frohlich, R.; Meyer, O. Organometallics
1997, 16, 5449-5456.
(43) Fryzuk, M. D.; Carter, A.; Rettig, S. J . Organometallics 1992,
11, 469-472.

432 Organometallics, Vol. 18, No. 3, 1999
Schrock et al.
°C. The 13C NMR spectrum at -30 °C shows a peak at
55.1 ppm (14 ppm downfield from the lower field methyl
resonance in [N2P]Zr(13CH3)2) which we assign to “{[N2P]-
Zr(13CH3)}+” (with solvent and/or anion associated with
it) as well as a resonance for Ph3C13CH3, the expected
product of methyl abstraction or oxidative cleavage, at
30.5 ppm. The 31P NMR spectrum shows a relatively
broad resonance at 26.8 ppm, 42.5 ppm downfield of the
31P resonance in [N2P]ZrMe2. No resonance for the
methyl group in the proton NMR spectrum of {[N2P]-
Zr(13CH3)}+ could be identified unambiguously, how-
ever. Evidence of decomposition is observed by 13C and
31P NMR within minutes after warming the sample to
room temperature. Similar results were obtained upon
treating [N2P]Zr(CH2Ph)2 with [Ph3C][B(C6F5)4] under
similar conditions. When 20 equiv of 1-hexene were
added to “{[N2P]Zr(CH3)}[B(C6F5)4]” in bromobenzene-
d5 and the reaction was held at 0 °C for 1 h, some poly-
1
(1-hexene) formed, according to H NMR spectra, al-
though >50% of the initial 1-hexene was still present.
Longer reaction times yielded little additional poly(1-
hexene). We conclude that while “{[N2P]Zr(13CH3)}+”
may be formed at 0 °C or below, it is not stable enough
to be an initiator for the controlled polymerization of
1-hexene under the conditions employed.
Th e [R2NP N]2-) Liga n d a n d [R2NP N]Zr Com -
p lexes (R ) t-Bu or 2,6-Me2C6H3). We hypothesized
that the instability of zirconium alkyl cations containing
the [N2P]2- ligand might be ascribed to some adverse
reaction involving the trimethylsilyl substituent on the
amido nitrogen atoms (e.g., CH activation or cleavage
of the Si-N bond). For this reason we turned to the
synthesis of diamido/phosphine ligands in which a
dimethylsilyl group is incorporated into the backbone
and an alkyl (t-Bu) or aryl (2,6-Me2C6H3) substituent
is present as an “external” substituent on the amido
nitrogen atoms. (The tert-butyl group has been used
successfully in [NON]2- complexes5,6 and 2,6-disubsti-
tuted aryl groups in complexes containing the [(Aryl-
NCH2CH2)2O]2- ligand.7,15) The potential advantage of
incorporating a dimethylsilyl group into the backbone
is that the metal will not have ready access to the CH
bonds in the silyl methyl groups in an intramolecular
reaction, and a variety of substituents on nitrogen in
theory could be employed.
F igu r e 2. (a) ORTEP drawing of the structure of [(t-Bu-
NSiMe2CH2)2P]Zr(CH3)Cl. (b) Top view of Chem 3D space-
filling drawing of the structure of [(t-BuNSiMe2CH2)2P]Zr-
(CH3)Cl (including protons).
although it is possible that this species is a dimer with
bridging chlorides.
Addition of 1 equiv of LiMe to [t-Bu2NPN]ZrCl2 yields
[t-Bu2NPN]ZrMeCl in good yield. The methyl ligand
appears to be located in the equatorial position on the
3
basis of the magnitude of J HP (11 Hz) for the methyl
resonance at 0.58 ppm in the proton NMR spectrum.
An X-ray study of [t-Bu2NPN]ZrMeCl showed this to be
the case (Tables 1 and 2, Figure 2). However, the
trigonal bipyramid is severely distorted (Figure 2a) in
that the “axial” chloride has been “pushed” from the
“ideal” axial position by the tert-butyl group containing
C(103), and in particular the methyl group bound to it
(C(105)), as judged from the P-Zr-Cl angle of only
146.37(2)°. A top view of a space-filling drawing (Figure
2b) reveals that the chloride has taken the only position
possible from a steric point of view, i.e., the apical
chloride is 3.50 Å from C(105), 3.46 Å from C(206), and
3.73 Å from C(204), and contacts with four surrounding
methyl protons range from 2.47 to 3.06 Å. Interactions
of this magnitude between the TMS methyl groups and
the apical methyl group on Zr are also found in
[N2P]Zr(CH3)(CH2Ph) (e.g., C(5)...C(23) ) 3.50 Å and
C(5)...C(13) ) 3.52 Å). The Zr-N(1)-C(103) angle in
[t-Bu2NPN]ZrMeCl is ∼9° smaller than the correspond-
ing angle in [N2P]Zr(CH3)(CH2Ph), which should con-
tribute to greater steric problems in terms of accommo-
dating the chloride ligand in the ideal apical position.
The Zr-P bond is shorter and the Zr-P-Cipso bond
angle is also significantly smaller in [t-Bu2NPN]ZrMeCl
than in [N2P]Zr(CH3)(CH2Ph). One readily quantifiable
The syntheses again are fashioned after those of
amidodiphosphine ligands17,18 and H2[N2P] described
above. The tert-butyl derivative can be prepared readily
as shown in eqs 6 and 7. The H2[t-Bu2NPN] compound
ClCH2SiMe2Cl + 2.1 t-BuNH2 ether8
ClCH2SiMe2NH-t-Bu (6)
2 ClCH2SiMe2NH-t-Bu + PhPH2 2.1 LiBu8
ether
PhP(CH2SiMe2NH-t-Bu)2 (7)
shown in eq 7 is isolated as a pale yellow oil in nearly
quantitative yield. Deprotonation with butyllithium in
pentane yields Li2[t-Bu2NPN], which reacts with ZrCl4-
(THF)2 in diethyl ether to yield colorless, crystalline
[t-Bu2NPN]ZrCl2 in 64% yield. Proton and carbon NMR
spectra of [t-Bu2NPN]ZrCl2 are consistent with a pseudo
trigonal bipyramidal complex containing a mirror plane,

Zr Complexes Containing Diamidophosphine Ligands
Organometallics, Vol. 18, No. 3, 1999 433
difference between [N2P]Zr(CH3)(CH2Ph) and [t-Bu2-
NPN]ZrMeCl is the length of the “arms” between P and
Zr. The average of the sum of the four distances in the
“arms” in [t-Bu2NPN]ZrMeCl (7.560 Å) is significantly
greater than that in [N2P]Zr(CH3)(CH2Ph) (6.917 Å),
primarily as a consequence of the larger size of Si versus
C. In the end, however, we can simply point to the
greater steric demand of a tert-butyl group near the
metal as perhaps the most important difference in steric
crowding between [N2P]Zr(CH3)(CH2Ph) and [t-Bu2-
NPN]ZrMeCl and the reason the chloride ligand cannot
occupy the axial position in [t-Bu2NPN]ZrMeCl.
One of the advantages of the [R2NPN]2- ligand is the
ability to vary the R group. For example, we could
readily prepare the 2,6-Me2C6H3 (Ar) derivative. The Ar
group was chosen on the basis of its relatively planar
form and in anticipation therefore that the structure of
[Ar2NPN]ZrMeCl would not show the dramatic steric
interaction that pushed the axial chloride from the axial
position in [t-Bu2NPN]ZrMeCl. H2[Ar2NPN] was pre-
pared by reactions analogous to those used to prepare
H2[t-Bu2NPN], and [Ar2NPN]ZrMe2 was prepared by
the route shown in eq 8. It is interesting to note that
F igu r e 3. ORTEP drawing of the structure of [(2,6-
Me2C6H3NSiMe2CH2)2P]Zr(CH3)Cl.
ZrMeCl, and [Ar2NPN]ZrMeCl. The Zr-P-Cipso angle
is similar to what it is in [t-Bu2NPN]ZrMeCl; indeed,
the C-P-C angle is virtually invariant in [N2P]Zr(CH3)-
(CH2Ph), [t-Bu2NPN]ZrMeCl, and [Ar2NPN]ZrMeCl.
The sum of the four distances in the ligand “arms” in
[Ar2NPN]ZrMeCl are virtually the same as in [t-Bu2-
NPN]ZrMeCl. The steric problems in the apical pocket
in [t-Bu2NPN]ZrMeCl clearly are not present in [Ar2-
NPN]ZrMeCl. The reason is most likely primarily the
planar nature of the Ar groups on the amido donors in
contrast to the spherical, sterically unyielding nature
of a tert-butyl group.
Zr(NMe2)4 H [Ar NPN]8 [Ar2NPN]Zr(NMe2)2
2
2
-2 Me2NH
2 HCl
8 [Ar2NPN]ZrCl2 2 MeMgCl8 [Ar2NPN]ZrMe2
-2 Me2NH
(8)
the ligand is not cleaved off upon addition of HCl to [Ar2-
NPN]Zr(NMe2)2, presumably as a consequence of the
multidentate nature of the [Ar2NPN]2- ligand. Even if
a proton adds to the amido nitrogen of the [Ar2NPN]2-
ligand instead of the dimethylamido ligand it must be
transferred to the dimethylamido ligand, before further
protonations or ligand degradation reactions result in
decomposition. Addition of only 1 equiv of MeMgCl to
[Ar2NPN]ZrCl2 leads to a mixture of [Ar2NPN]ZrMe2
and [Ar2NPN]ZrMeCl. [Ar2NPN]ZrMeCl could be crys-
tallized from a CH2Cl2/pentane mixture at -35 °C to
afford colorless crystals of X-ray crystallography quality
in 30% yield. NMR spectra of both [Ar2NPN]ZrMe2 and
[Ar2NPN]ZrMeCl are fully consistent with the expected
fac structures. Proton NMR data suggest that the
methyl group in [Ar2NPN]ZrMeCl is in an equatorial
position (3J HP ) 8.8 Hz), while in [Ar2NPN]ZrMe2 J HP
values for the methyl groups are 6.6 and 1.5 Hz in what
we presume to be Meeq and Meax, respectively.
An X-ray study of [Ar2NPN]ZrMeCl showed it to be a
trigonal bipyramidal species in which the apical chloride
is strictly trans to the phosphorus donor (Tables 1 and
2; Figure 3), as judged by the Cl-Zr-P angle of 179.44-
(6)°. Interestingly, the Zr-Cl distance in [Ar2NPN]-
ZrMeCl (2.715(3) Å) is ∼0.2 Å longer than the Zr-Cl
distance in [t-Bu2NPN]ZrMeCl, perhaps as a conse-
quence of the chloride being strictly trans to the P donor.
The Zr-P distance is similar to what it is in [N2P]Zr-
(CH3)(CH2Ph) rather than [t-Bu2NPN]ZrMeCl. One of
the Ar groups is virtually “upright”, as judged by the
P-Zr-N(1)-C angle of 178.2°, while the other is tipped
to a significant degree (P-Zr-N(2)-C ) 151.9°). Con-
sequently the Zr-N(1)-C angle is only 108.6(4)°, while
Zr-N(2)-C ) 113.4(5); both are the smallest of the Zr-
N-X angles in [N2P]Zr(CH3)(CH2Ph), [t-Bu2NPN]-
Addition of 2 equiv of MeMgCl or LiMe to [t-Bu2NPN]-
ZrCl2 (or 1 equiv to [t-Bu2NPN]ZrMeCl) yields complex
mixtures in which there is no evidence for [t-Bu2NPN]-
ZrMe2, according to NMR spectra. When methyllithium
was employed, a product could be isolated in ∼25% yield
1
that contains only one tert-butyl group (eq 9). The H
NMR spectrum of this product in C6D6 is consistent with
a compound that has no symmetry about zirconium and
3
one “equatorial” methyl ligand (δ ) 0.87 ppm with J HP
) 10 Hz). An X-ray study showed this product to be a
dimer of the imido complex, “[t-BuNSiMe2CH2P(Ph)CH2-
SiMe2N]ZrMe”, in which the imido nitrogen is bridging
between two Zr centers to yield a Zr2(µ-N)2 ring (Tables
1 and 2; Figure 4). We hypothesize that electron transfer
to Zr followed by loss of chloride ion and a tert-butyl
radical leads to “[t-BuNSiMe2CH2P(Ph)CH2SiMe2N]-
ZrMe”, which then dimerizes to give the observed
product. Evidently steric crowding prevents nucleophilic
displacement of the chloride in [t-Bu2NPN]ZrMeCl, or
the distorted structure of [t-Bu2NPN]ZrMeCl makes it
more susceptible to electron transfer, or both. No
method of isolating any other product of the reaction
between [t-Bu2NPN]ZrCl2 and 2 equiv of MeMgCl or
LiMe has been found.
The structure of {[t-BuNSiMe2CH2P(Ph)CH2SiMe2N]-
ZrMe}2 cannot be compared directly with the structures

434 Organometallics, Vol. 18, No. 3, 1999
Schrock et al.
“outside” the ligand backbone or “inside” the ligand
backbone, rather than the presence of phosphorus per
se. Therefore if olefin polymerization is the goal, we will
have to prepare and test other types of diamidophos-
phine ligands that have no N-Si bonds. However, the
diamido/phosphine ligands described here, in part be-
cause of their “hard/soft” multidentate nature, may offer
opportunities for preparing a variety of complexes that
contain a metal outside of group 4 in less demanding
environments than in a zirconium “cation”.
Exp er im en ta l Section
Gen er a l Deta ils. All experiments were conducted under
nitrogen in a Vacuum Atmospheres drybox, using standard
Schlenk techniques, or on a high-vacuum line (<10-4 Torr).
Pentane was washed with HNO3/H2SO4 (5/95 v/v), sodium
bicarbonate, and water, stored over CaCl2, and then distilled
from sodium benzophenone under nitrogen. Reagent grade
benzene was distilled from sodium benzophenone under
nitrogen. Toluene was distilled from molten sodium. Methylene
chloride was distilled from CaH2. Reagent grade ether and
THF were sparged with nitrogen and passed through alumina
columns.50 Aldrich anhydrous grade DME was sparged with
argon and brought into the drybox. All solvents were stored
in the drybox over activated 4 Å molecular sieves. Deuterated
solvents were freeze-pump-thaw degassed and vacuum
transferred from an appropriate drying agent or sparged with
F igu r e 4. ORTEP drawing of the structure of {[t-Bu-
NSiMe2CH2P(Ph)CH2SiMe2N)Zr(CH3)}2.
of [N2P]Zr(CH3)(CH2Ph), [t-Bu2NPN]ZrMeCl, and [Ar2-
NPN]ZrMeCl as a consequence of the restrictions im-
posed by the formation of the Zr2(µ-N)2 ring in the
dimer, i.e., the “axial” ligand for each Zr is now the
“imido” donor from the other half of the molecule, and
the trigonal bipyramidal geometry about each Zr is
consequently distorted. The Lax-Zr-P angles are re-
stricted to ∼155° and a measure of the “steric pressure”
at the apical position therefore is not possible. The Zr-
(1)-N(11) and Zr(2)-N(21) bond lengths are similar to
Zr-N(amido) bond lengths in other molecules discussed
here, while the Zr-P distances and the Zr-P-Cipso
angles are similar to those in [t-Bu2NPN]ZrMeCl and
[Ar2NPN]ZrMeCl. Other distances and angles can be
found in Table 2 and will not be discussed in any detail.
The reaction between [Ar2NPN]ZrMe2 and [Ph3C]-
[B(C6F5)4] in bromobenzene or chlorobenzene at -30 °C
1
argon and stored over 4 Å sieves. H and 13C data are listed
in parts per million downfield from tetramethylsilane and were
referenced using the residual protonated solvent peak. Unless
otherwise noted, NMR experiments were run in C6D6 solution
and 13C and 31P spectra were proton-decoupled. Coupling
constants are given in hertz, and routine couplings are not
listed. Elemental analyses (C, H, N) were performed on a
Perkin-Elmer 2400 CHN analyzer in our own laboratory or
by Kolbe Microanalytical Laboratory (Mu¨lheim an der Ruhr,
Germany). Column chromatography was performed by the
method of Still.51
Zr(NMe2)4 was prepared by a literature procedure.52 ClMe2-
SiCH2CH2SiMe2Cl was purchased from a commercial source.
13CH3MgI was prepared from 13CH3I (Cambridge Isotopes) and
magnesium in ether. Grignard reagents were titrated with
n-propanol using 1,10-phenanthroline as an indicator before
use.
afforded a mixture of different species, according to 31
P
NMR spectra. More complex mixtures were formed upon
warming the sample to -20 °C. Attempts to prepare a
cationic dimethylamine adduct by protonating a methyl
ligand in [Ar2NPN]ZrMe2 with [PhNMe2H][B(C6F5)4]
also gave mixtures of unstable species. [Ar2NPN]ZrMe2
in bromobenzene-d5 was activated by addition of [Ph3C]-
[B(C6F5)4] at -35 °C and the solution was kept at 0 °C
for 30 min. Addition of several equivalents of 1-hexene
resulted in incomplete polymerization, as evidenced by
1H NMR. The 1H NMR spectrum also showed broad
olefinic resonances, which suggests that â-hydride
elimination occurs during the polymerization. We con-
clude that cationic species formed from [Ar2NPN]ZrMe2
are not stable under the conditions employed and not
adequate as initiators for polymerization of 1-hexene
under the conditions employed.
All X-ray data were collected on a Siemens SMART/CCD
diffractometer with λ(Mo KR) ) 0.710 73 Å using ω scans and
solved using a full-matrix least-squares refinement on F2. No
absorption correction was applied in any case. All procedures
were analogous to those described elsewhere.53 (See also the
Supporting Information.)
ClCH2CH2(cyclo-NSiMe2CH2CH2SiMe2). A 1 L flask was
charged with ClCH2CH2NH3Cl (32.3 g, 0.278 mol), triethyl-
amine (128 mL, 0.835 mol, 3.3 equiv), and 600 mL of CH2Cl2
(dried solvent is unnecessary). A solution of ClMe2SiCH2CH2-
SiMe2Cl in 200 mL of CH2Cl2 was prepared in the drybox. It
was added slowly via a dropping funnel to the well-stirred
slurry of ClCH2CH2NH3Cl over a period of 1 h. The reaction
mixture was stirred overnight, and the voluminous precipitate
of NEt3HCl was filtered off. The dichloromethane solution was
evaporated, and the residue was extracted with hexane. The
Con clu sion s
The ligands reported here have a “fixed” geometry
that imposes some significant steric pressure on the
apical coordination site, the degree of which depends
markedly on the nature of the amido substituent and
follows the order Ar < SiMe3 , t-Bu. This “fixed” fac
geometry consequently in theory would allow the sterics
to be finely adjusted. Unfortunately, as far as cationic
zirconium polymerization catalysts are concerned, the
ligands do not seem stable enough to support a cationic
zirconium center. We hypothesize that the instability
of “cations” can be ascribed to the presence of Si, either
(50) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J . Organometallics 1996, 15, 1518.
(51) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.
(52) Diamond, G. M.; Rodewald, S.; J ordan, R. F. Organometallics
1995, 14, 5.
(53) Rosenberger, C.; Schrock, R. R.; Davis, W. M. Inorg. Chem.
1997, 36, 123.

Zr Complexes Containing Diamidophosphine Ligands
Organometallics, Vol. 18, No. 3, 1999 435
NEt3HCl was also thoroughly extracted with hexane. The
extracts were combined, and the solvents were removed in
vacuo. The residue was distilled in vacuo (bp 45 °C at 100
mTorr) to give the product as a colorless liquid, which became
slightly cloudy upon standing; yield 45.3 g (73%): 1H NMR δ
3.18 (m, 2, CH2), 3.00 (m, 2, CH2), 0.665 (s, 4, SiCH2CH2Si),
0.040 (s, 12, Me2Si); 13C NMR δ 45.6 (CH2), 45.1 (CH2), 8.12
(SiCH2CH2Si), -0.158 (SiMe2).
LiBu (2.5 M in hexanes, 9.4 mL, 24 mmol) was added. The
reaction was stirred at 22 °C for 50 min, and the volume
reduced to ∼30 mL in vacuo. The reaction was cooled to -40
°C, and crystallization of the product allowed to proceed. The
product was filtered off and rinsed quickly with cold pentane.
A second crop was obtained similarly for a combined yield of
2.54 g (62%): 1H NMR (THF-d8) δ 7.45 (t, 2, Ph), 7.24 (m, 3,
Ph), 3.23 (m, 4, NCH2CH2P), 1.91 (m, 4, NCH2CH2P), -0.068
(s, 18, Si(CH3)3); 13C NMR δ 143.6, 132.1, 128.8, 128.1 (Ph),
P h P [CH2CH2(cyclo-NSiMe2CH2CH2SiMe2)]2. In the dry-
box, a 500 mL Schlenk flask was charged with 300 mL of THF,
ClCH2CH2(cyclo-NSiMe2CH2CH2SiMe2) (50.0 g, 0.225 mol),
and a stir bar. It was fitted with a septum and connected to a
Schlenk line. Phenylphosphine (12.4 mL, 0.113 mol) was intro-
duced via syringe. The flask was cooled to -10 °C (ice/acetone
bath) and fitted with an addition funnel containing 2.5 M LiBu
in hexane (90.1 mL, 0.225 mol). The butyllithium solution was
added dropwise over 1.5 h. After the addition was complete,
the reaction was warmed to room temperature and stirred
overnight. 31P NMR showed clean conversion to product, which
is stable enough to be worked up in air. The volatile compo-
nents were removed in vacuo, and the residue was extracted
with hexane (200 mL). This solution was filtered through a
bed of Celite. The hexane was removed in vacuo to yield the
product as a light yellow oil; yield 54.3 g (100%): 1H NMR δ
7.50 (t, 2, Ph), 7.36 (d, 3, Ph), 2.81 (m, 4, CH2), 1.80 (m, 4,
CH2), 0.655 (s, 8, SiCH2CH2Si), -0.0153 (s, 24, SiMe2); 13C
NMR δ 139.1 (d, Cipso), 132.7 (d, Cm), 129.1 (Cp), 128.7 (d, Co),
39.8 (d, 1J CP ) 24, NCH2CH2P), 34.6 (d, 2J CP ) 15, NCH2CH2P),
8.37 (SiCH2CH2Si), 0.19 (Si(CH3)2); 31P NMR (THF) -33.2.
P h P (CH2CH2NH3Cl)2. Under air, a 500 mL round-bot-
tomed flask was charged with PhP[CH2CH2(cyclo-NSiMe2CH2-
CH2SiMe2)]2 (54.3 g, 0.113 mol) and 350 mL of ether. The
reaction flask was cooled on an ice bath, and a dilute solution
of HCl (24 mL of 12 M HCl in 75 mL of water) was added to
the ethereal solution over 5 min. After 24 h the ether and
water layers were separated, and the aqueous layer was
washed with ether (2 × 100 mL). The water was removed by
rotary evaporation with a bath temperature of 60 °C to give
the crude product as an off-white oily mass. Ethanol (800 mL,
sparged with argon) was added, and the mixture was heated
under argon in an 80 °C oil bath for 20 min with good stirring.
White microcrystals formed, which were isolated on a Bu¨chner
funnel. A second crop was obtained by reducing the volume of
the mother liquor to ∼250 mL, which resulted in more product
oiling out. Heating this mixture as before led to formation of
a second crop of microcrystals. The product was dried at 50
°C in vacuo to remove the last traces of ethanol; yield 19.9 g
(65%): 1H NMR (DMSO-d6) δ 8.22 (6, NH3+), 7.55 (2, Ph), 7.41
1
46.2 (d, J CP ) 16, NCH2CH2P), 36.4 (NCH2CH2P), 2.11 (Si-
(CH3)3); 31P NMR (THF-d8) δ -29.2.
[N2P ]Zr Cl2. H2[N2P] (2.00 g, 5.87 mmol) was dissolved in
60 mL of pentane. The solution was cooled to -40 °C, and Zr-
(NMe2)4 (1.57 g, 5.87 mmol) was added as a solid. The reaction
was stirred overnight and filtered to remove a small amount
of precipitate. The solvents were removed under reduced
pressure to give [N2P]Zr(NMe2)2 as an oil that could not be
induced to crystallize: 1H NMR δ 7.35 (tt, 2, Ph), 7.02 (d, 3,
Ph), 3.5 (m, 2, NCH2CH2P), 3.2 (m, 2, NCH2CH2P), 3.13 (s, 6,
NMe2), 3.05 (s, 6, NMe2), 1.99 (m, 2, NCH2CH2P), 1.68 (m, 2,
NCH2CH2P), 0.30 (s, 18, SiMe3); 31P NMR δ -10.5.
[N2P]Zr(NMe2)2 was dissolved in 40 mL of pentane, and Me3-
SiCl (1.49 mL, 11.7 mmol) was added by syringe. The reaction
was stirred vigorously for 10 min and then allowed to stand
for 2 h. The off-white crystalline solid that formed was isolated
on
a frit and dried in vacuo, 2.36 g (80%). No further
purification was necessary, although the complex may be
recrystallized from a mixture of toluene and pentane: 1H NMR
δ 7.63 (t, 2, Ph), 7.13 (m, 3, Ph), 2.94 (br m, 2, NCH2CH2P),
2.73 (m, 2, NCH2CH2P), 1.91 (m, 4, NCH2CH2P), 0.37 (s, 18,
SiMe3); 13C NMR δ 133.0, 130.1, 129.0, 125.6 (Ph), 50.0 (d, J CP
) 15, NCH2CH2P), 38.3 (d, J CP ) 20, NCH2CH2P), 1.30 (Si-
(CH3)3); 31P NMR δ 1.94. Anal. Calcd for C16H31N2PSi2ZrCl2:
C, 38.38; H, 6.24; N, 5.59. Found: C, 38.53; H, 6.20; N, 5.52.
[N2P ]Zr (CH3)(THF )Cl. [N2P]ZrCl2 (300 mg, 0.599 mmol)
was dissolved in 20 mL of ether, and the solution was cooled
to -40 °C in the drybox freezer. MeMgCl (3.0 M in THF, 100
µL, 0.300 mmol) was added via syringe over a period of 4 min.
The solution was placed back in the freezer for 15 min, and
then another portion of MeMgCl (100 µL, 0.300 mmol) was
added. After 30 min the solvents were removed in vacuo, and
the reside was extracted with 40 mL of pentane. The extract
was filtered through Celite, and the solvent removed in vacuo.
The residue was recrystallized from pentane at -40 °C to give
the product as white crystals, yield 140 mg (42%): 1H NMR δ
7.32 (m, 2, Ph), 7.02 (m, 3, Ph), 3.64 (m, 4, THF), 3.2 (m, 4,
NCH2CH2P), 1.8 (m, 4, NCH2CH2P), 1.33 (m, 4, THF), 0.84
(d, 2J HP ) 7, 3, Me), 0.42 (s, 18, SiMe3); 31P NMR δ -0.49. Anal.
Calcd for C21H42N2PSi2ClOZr: C, 45.66; H, 7.66; N, 5.07.
Found: C, 45.54; H, 7.85; N, 5.02.
(3, Ph), 2.78 (br m, 4, NCH2CH2P), 2.10 (t, 4, NCH2CH2P); 31
P
NMR (DMSO-d6) δ -29.6.
P h P (CH2CH2NHTMS)2. In the drybox, a 500 mL round-
bottomed flask was charged with PhP(CH2CH2NH3Cl)2 (10.0
g, 37.2 mmol) and 300 mL of THF. The slurry was cooled to
-40 °C, and LiBu (2.5 M in hexanes, 59.4 mL, 149 mmol) was
slowly added via syringe in small portions. After stirring the
mixture at room temperature for 2.5 h it was again cooled to
-40 °C, and Me3SiCl (9.9 mL, 78.0 mmol) was added via
syringe. The mixture was stirred for 3 h at 22 °C, and all
solvents were removed in vacuo. The oily residue was extracted
with 180 mL of pentane, and the extract was filtered through
a bed of Celite. The pentane was removed from the filtrate in
vacuo to give the product as a brown oil in quantitative yield
(12.6 g): 1H NMR δ 7.58 (t, 2, Ph), 7.12 (m, 3, Ph), 2.82 (m, 4,
NCH2CH2P), 1.79 (m, 4, NCH2CH2P), 0.3 (br s, 2, NH), 0.01
(s, 18, Si(CH3)3); 13C NMR δ 139.0 (d, Cipso), 132.7 (d, Cm), 129.0
[N2P ]Zr (CH3)Cl. [N2P]ZrCl2 (350 mg, 0.699 mmol) was
dissolved in 20 mL of ether, and the solution was cooled to
-40 °C. MgMe2 (0.82 M in ether, 426 µL, 0.350 mmol) was
added by syringe, and the reaction was stirred for 1 h at room
temperature. The ether was removed in vacuo, and the residue
was extracted with 40 mL of pentane. The extract was filtered
through Celite, and the volume of the filtrate was reduced to
∼20 mL in vacuo. After storing the solution at -40 °C for 15
h the granular product was collected; yield 223 mg in two crops
(66%): 1H NMR δ 7.3 (m, 2, Ph), 6.95 (m, 3, Ph), 3.25 (m, 4,
NCH2CH2P), 1.8 (m, 4, NCH2CH2P), 0.9 (s, 3, CH3), 0.40 (s,
18, SiMe3); 31P NMR δ -1.6. Several attempts to obtain
analytical data for [N2P]Zr(CH3)Cl failed.
[N2P ]Zr (i-Bu )Cl. [N2P]ZrCl2 (200 mg, 0.399 mmol) was
dissolved in 15 mL of ether, and the solution was cooled to
-40 °C. i-BuMgCl (2.16 M in ether, 185 µL, 0.399 mmol) was
added by syringe, and the reaction was stirred at room
temperature for 2 h. Dioxane (41 µL, 0.479 mmol) was added,
and the precipitate allowed to settle for 30 min. The mixture
was filtered through a short plug of Celite, and the solvents
were removed in vacuo. The residue was dissolved in ∼1 mL
1
(d, Cp), 128.8 (d, Co), 39.7 (d, J CP ) 24, NCH2CH2P), 34.6 (d,
2J CP ) 15), 8.37 (SiCH2CH2Si), 0.191 (Si(CH3)2); 31P NMR δ
-35.7.
P h P (CH2CH2NLiTMS)2. A 100 mL round-bottomed flask
was charged with PhP(CH2CH2NHTMS)2 (4.00 g, 11.7 mmol)
and 70 mL of pentane. The mixture was cooled to -40 °C, and

436 Organometallics, Vol. 18, No. 3, 1999
Schrock et al.
of ether, to which a layer of pentane was carefully added. The
product precipitated as a light yellow powder as the solvents
slowly diffused together; yield 137 mg (66%): 1H NMR δ 7.34
(m, 2, Ph), 7.03 (m, 3, Ph), 3.3 (dt, 4, NCH2CH2P), 2.1 (sept, 1,
CH2CH(CH3)2), 1.88 (m, 4, NCH2CH2P), 1.5 (virtual triplet,
added, and a white precipitate formed. The reaction mixture
was stirred overnight at room temperature, and the solvents
were removed in vacuo. The residue was extracted with
pentane. The extract was filtered through Celite, and the
pentane was removed from the filtrate in vacuo to give a
3
1
3J HP ) 7.7, J HH ) 6.8, 2, CH2CH(CH3)2), 1.07 (d, 6, CH2CH-
colorless oil (59 g, 0.33mol; 94% yield). H NMR δ 2.57 (s, 2,
(CH3)2), 0.37 (s, 18, SiMe3); 13C NMR δ 134, 132, 130, 129 (Ph),
70.9 (CH2CH(CH3)2), 48 (d, NCH2CH2P), 37.8 (d, NCH2CH2P),
CH2), 0.99 (s, 9, t-Bu), 0.5 (br s, 1, NH), 0.11 (s, 6, Si(CH3);
13C{1H} δ 49.7 (s, NC(CH3)3), 34.0 (s, NC(CH3)3), 32.4 (s, NCH2-
Si), 0.7 (s, Si(CH3)2).
3
29.9 (d, J CP ) 5, CH2CH(CH3)2), 28.2 (s, CH2CH(CH3)2), 1.1
(s, Si(CH3)3; 31P NMR δ 1.19. Anal. Calcd for C20H40N2Si2-
PClZr: C, 45.99; H, 7.72; N, 5.36. Found: C, 45.52; H, 7.53;
N, 5.37.
P h P (CH2SiMe2NH-t-Bu )2. A solution of 2.5 M LiBu in
hexane (58.5 mL, 1.5 mol) and a solution of PhPH2 (15.4 g,
1.4 mol) in diethyl ether (300 mL) were cooled to -35 °C in
the drybox. The LiBu solution was then added to the phosphine
solution. The mixture stood for 1 h at room temperature. A
solution of ClCH2SiMe2NH-t-Bu (25.2 g, 1.4 mol) in diethyl
ether (30 mL) was then added at -35 °C, and the reaction
mixture was stirred for 1 h at room temperature. Again the
reaction mixture was cooled to -35 °C, and another 58 mL of
2.5 M LiBu solution was added. The mixture stood for 1 h at
room temperature, and a solution of ClCH2SiMe2NH-t-Bu (25.2
g, 1.4 mol) in diethyl ether was then added at -35 °C. The
reaction mixture was stirred for 2 h at room temperature, and
the solvent was removed in vacuo. The residue was extracted
with pentane, and the extract was filtered through Celite. The
solvent was removed from the filtrate in vacuo to afford a pale
yellow oil that was distilled (105 °C, 100 mTorr) to give the
product as a colorless oil (47 g, 1.19 mol; 85% yield): 1H NMR
δ 7.68 (m, 2, Ph), 7.18 (m, 3, Ph), 1.14 (m, 2, CHaHb), 1.08 (s,
18, t-Bu), 0.99 (m, 2, CHaHb), 0.55 (br s, 2, NH), 0.17 (s, 6,
[N2P ]Zr (CH3)2. [N2P]ZrCl2 (260 mg, 0.519 mmol) was
dissolved in 15 mL of ether. The solution was cooled to -40
°C, and MeMgCl (3.0 M in THF, 346 µL, 1.04 mmol) was added
by syringe. The reaction was stirred for 45 min at room
temperature. The volatile components were removed in vacuo,
and the residue was extracted with 12 mL of pentane. After 1
h the mixture was filtered and the solvents were removed from
the filtrate in vacuo to yield the product as an oil (220 mg,
92%) that could not be induced to crystallize: 1H NMR δ 7.3
(m, 2, Ph), 7.0 (m, 3, Ph), 3.4 (m, 2, NCH2CH2P), 3.1 (m, 2,
NCH2CH2P), 1.8 (m, 2, NCH2CH2P), 1.62 (m, 2, NCH2CH2P),
2
0.80 (d, J HP ) 6, 3, cis-Me), 0.60 (s, 3, trans-Me).
[N2P]Zr(13CH3)2 was prepared similarly: 13C NMR δ 35.9
1
1
(2J CP ) 29, J CH ) 113), 40.9 (2J CP ) 2, J CH ) 114); 31P NMR
δ -15.7.
[N2P ]Zr (CH2P h )2. [N2P]ZrCl2 (150 mg, 0.300 mmol) was
dissolved in 10 mL of ether. The solution was cooled to -40
°C, and C6H5CH2MgCl (1.0 M in ether, 599 µL, 0.599 mmol)
was added by syringe. After 3 h, a 31P NMR spectrum showed
that the reaction was complete. Dioxane (56 µL, 0.66 mmol)
was added, and the precipitate was allowed to settle. The
reaction was filtered through Celite, and the volatile compo-
nents were removed under reduced pressure. The residue was
recrystallized from a mixture of ether and pentane at -40 °C
to give the product as yellow crystals (120 mg in two crops;
65%): 1H NMR δ 7.28 (d, 4, Ph), 7.05 (m, 2, Ph), 6.95 (m, 2,
Ph), 6.7 (m, 2, Ph), 3.15 (m, 2, NCH2CH2P), 2.8 (m, 2, NCH2-
1
SiMe), 0.15 (s, 6, SiMe); 13C{1H} δ 133.7 (d, J CP ) 22, Cipso),
129.6 (Cm), 128.9 (Cp), 128.7 (Co), 49.9 (NC(CH3)3), 34.2 (NC-
1
3
(CH3)3), 22.9 (d, J CP )30, CH2), 3.6 (d, J CP ) 4, Si(CH3)a-
(CH3)b), 3.5 (d, 3J CP ) 4, Si(CH3)a(CH3)b); 31P{1H} δ -34.4. Anal.
Calcd for C20H41N2PSi2: C, 60.55; H, 10.42; N, 7.06. Found:
C, 60.57; H, 10.34; N, 7.12.
[t-Bu 2NP N]Zr Cl2. A -35 °C solution of PhP[CH2SiMe2N-
(Li)(t-Bu)]2 (2.88 g, 7 mmol) in diethyl ether (15 mL) was added
to a slurry of ZrCl4(THF)2 (2.66 g, 7 mmol) in diethyl ether
(40 mL) at -35 °C, and the reaction was stirred overnight at
room temperature. The reaction mixture was filtered through
Celite, and the volume of the filtrate was reduced to 15 mL in
vacuo. The product crystallized upon storing the solution
overnight at -35 °C; yield 2.5 g (4.5 mmol, 64%): 1H NMR δ
7.95 (m, 2, Ph), 7.11 (m, 3, Ph), 1.59 (s, 18, t-Bu), 1.27 (br m,
2, CHaHb), 0.82 (m, 2, CHaHb), 0.24 (s, 6, SiMe), 0.15 (br s, 6,
3
3
CH2P), 2.75 (d, J HP ) 6.6, 2, cis-CH2C6H5), 2.69 (d, J HP
)
2.4, 2, trans-CH2C6H5), 1.65 (m, 4, NCH2CH2P), 0.294 (s, 18,
SiMe3); 13C NMR δ 149.6 (Cipso), 143.5 (Cm), 135.9 (Cp), 131.7
(Co), 129.3, 128.9, 128.8, 128.7, 127.3, 126.8, 122.3, 120.8, 69.3
1
1
(2J CP ) 3.2, J CH ) 126, cis-CH2C6H5), 65.9 (2J CP ) 22, J CH
)
118, trans-CH2C6H5), 47.7 (d, NCH2CH2P), 37.1 (d, NCH2-
1
SiMe); 13C{1H} δ 134.0 (d, J CP ) 10, Cipso), 131.3 (Cm), 129.3
CH2P), 1.40 (SiMe3); 31P NMR δ -7.08. Anal. Calcd for
(Cp), 129.2 (Co), 60.0 (NC(CH3)3), 33.6 (NC(CH3)3), 17.9 (CH2),
7.1 (Si(CH3)a(CH3)b), 5.9 (d, 3J CP ) 8, Si(CH3)a(CH3)b); 31P{1H}
(C6D6) δ -10.9; 31P{1H} (THF) δ -9.8.
The compound was also recrystallized from C6H6 by dis-
solving it in hot C6H6 and cooling the solution to room tem-
perature overnight. Large colorless crystals were collected
whose proton NMR spectrum in toluene showed 5/6 molecule
of C6H6 per Zr atom to be present. Anal. Calcd for C25H44Cl2N2-
PSi2Zr: C, 48.28; H, 7.13; N, 4.50. Found: C, 48.20; H, 7.13;
N, 4.51.
C
30H45N2PSi2Zr: C, 58.87; H, 7.41; N, 4.58. Found: C, 58.71;
H, 7.55; N, 4.47.
[N2P ]Zr (13CH3)(CH2P h ). [N2P]ZrCl2 (250 mg, 0.499 mmol)
was dissolved in 20 mL ether, and the solution was cooled to
-40 °C. 13CH3MgI (1.4 M in ether, 423 µL, 0.50 mmol) was
added by syringe, and the reaction was stirred for 40 min. The
reaction mixture was again cooled to -40 °C, and C6H5CH2-
MgCl (1.0 M in ether, 500 µL, 0.499 mmol) was added. The
mixture was stirred for 1.3 h, and dioxane (98 µL) was added.
The precipitate was allowed to settle for 45 min, and the
solution was filtered through a plug of Celite. The ether was
removed from the filtrate in vacuo, and the crude product was
recrystallized from ether, 169 mg (63%): 1H NMR δ 7.4 (t, Ph),
[t-Bu 2NP N]Zr MeCl. A 1.4 M solution of LiMe (256 mL,
0.36 mmol) in diethyl ether was added to a solution of [PhP-
(CH2SiMe2N-t-Bu)2]ZrCl2 (200 mg, 0.36 mmol) in diethyl ether
(6 mL). The reaction was stirred at room temperature for only
5 min before filtering the cloudy yellow solution through
glasswool paper. The yellow filtrate was placed in the -30 °C
freezer overnight, and white crystals were isolated (120 mg,
0.225 mmol; 62%): 1H NMR (CD2Cl2) δ 7.78 (m, 2, Ph), 7.43
(m, 3, Ph), 1.63 (s, 18, t-Bu), 1.59 (m, 2, CHaHb), 1.21 (m, 2,
3
7.1 (m, Ph), 6.8 (t, Ph), 3.25 (m, 2, NCH2CH2P), 2.82 (d, J HP
) 9, cis-CH2C6H5), 2.61 (m, 2, NCH2CH2P), 1.8 (m, 2, NCH2-
CH2P), 1.62 (m, NCH2CH2P), 0.588 (d, 3, trans-13Me), 0.304
(s, 18, SiMe3); 13C NMR δ 131.9, 129,7 128.9, 127.4, 122.3, 62.4
(cis-CH2C6H5, 2J CP ) 4.6, 1J CH ) 130), 48.7 (NCH2CH2P), 38.2
(d, trans-13CH3, 2J CP ) 27.9), 37.7 (NCH2CH2P), 0.927 (SiMe3);
31P NMR δ -6.56 (d). Anal. Calcd for C24H41N2PSi2Zr (all
natural abundance 13C): C, 53.78; H, 7.71; N, 5.23. Found:
C, 54.08; H, 7.32; N, 5.17.
3
CHaHb), 0.58 (d, J HP ) 11, 3, ZrMe), 0.41(br s, 6, SiMe), 0.18
(br s, 6, SiMe); 31P{1H} (CD2Cl2) δ -0.5. Anal. Calcd for C21H42
-
ClN2PSi2Zr: C, 47.02; H, 7.89; N, 5.22. Found: C, 46.88; H,
7.95; N, 5.09.
{[t-Bu NSiMe2CH2P (P h )CH2SiMe2N]Zr Me}2. A -35 °C
1.4 M solution of LiMe (512 µL, 0.72 mmol) in diethyl ether
ClCH2SiMe2NH(t-Bu ). A solution of dry t-BuNH2 (53.7 g,
0.73 mol) in diethyl ether (300 mL) was cooled to -35 °C in
the drybox. A solution of ClCH2SiMe2Cl (50 g, 0.35 mol) was

Zr Complexes Containing Diamidophosphine Ligands
Organometallics, Vol. 18, No. 3, 1999 437
was added to a solution of [t-Bu2NPN]ZrCl2 (200 mg, 0.36
mmol) in diethyl ether (8 mL). The reaction was stirred at room
temperature for 10 min. A white precipitate formed, and the
reaction mixture turned pale yellow. The solvents were
removed in vacuo, and the residue was extracted with 8 mL
of pentane. The extract was filtered, and the volume was
reduced to ∼1 mL in vacuo. The product is highly soluble in
pentane, but 40 mg (0.09 mmol, 25%) could be isolated in
crystalline form upon storing a pentane solution at -35 °C
for several days: 1H NMR δ 7.78 (m, 2, Ph), 7.18 (m, 3, Ph),
1.64 (s, 9, t-Bu), 1.32 (m, 2, CHaHb), 0.98 (m, 2, CHaHb), 0.87
and dried in vacuo, 1.35 g (84%): 1H NMR δ 7.96 (m, 2, PhP),
7.15 (m, 3, PhP), 7.00 (d, 4, Hm), 6.90 (t, 2, Hp), 2.50 (s, 12,
Meo), 1.24 (m, 4, CH2), 0.16 (s, 6, SiMe), -0.20 (s, 6, SiMe);
1
13C{1H} (60 °C) δ 147.07, 147.02, 136.3, 136.1, 135.1 (d, J CP
) 16), 132.7, 132.6, 131.1, 129.9, 129.5, 129.4, 125.9, 22.0 (s,
1
3
Meo), 21.6 (s, Meo), 18.8 (d, J CP ) 5, CH2), 3.8 (d, J CP ) 4.6,
SiMe), 2.0 (d, J CP ) 3.8, SiMe); 31P{1H} δ -15.2. Anal. Calcd
3
for C28H39Cl2N2PSi2Zr: C, 51.51; H, 6.02; N, 4.29; Cl, 10.86.
Found: C, 51.38; H, 6.05; N, 4.22; Cl, 10.95.
[Ar 2NP N]Zr MeCl. A 3.0 M solution of MeMgBr in ether
(150 µL, 0.46 mmol) was added to a solution of [Ar2NPN]ZrCl2
(300 mg, 0.46 mmol) in CH2Cl2 (8 mL) at -35 °C. The reaction
mixture was stirred at room temperature for 1 h. The solution
was treated with dioxane, and the cloudy mixture was filtered.
The solvents were removed from the filtrate in vacuo and the
off-white crystalline material was recrystallized from dichlo-
romethane/pentane mixtures to give X-ray crystallography
quality crystals in 30% yield (87 mg, 0.14 mmol): 1H NMR
(CD2Cl2) δ 7.74 (m, 2, PhP), 7.51 (m, 3, PhP), 7.05 (m, 4, Hm),
7.02 (m, 2, Hp), 2.40 (s, 6, Meo), 2.22 (s, 6, Meo), 1.73 (m, 4,
CH2), 0.54 (d, 3J HP ) 8.8, 3, ZrMe), 0.28 (s, 6, SiMe), 0.04 (s, 6,
SiMe); 31P{1H} (CD2Cl2) δ -12.0.
3
(d, J HP ) 10, 3, ZrMe), 0.68 (s, 3, SiMe), 0.60 (s, 3, SiMe),
0.34 (s, 3, SiMe), -0.07 (s, 3, SiMe); 31P{1H} δ -19.8.
ClCH2SiMe2NHAr . Li[NH(2,6-Me2C6H3)] (16.1 g, 127 mmol)
was added as a solid to a solution of ClCH2SiMe2Cl (18.2 g,
127 mmol) in diethyl ether (120 mL) at -35 °C. A white solid
formed, and the reaction was stirred overnight at room
temperature. The mixture was then filtered through Celite,
and solvents were removed from the filtrate in vacuo to give
a yellow oil (26 g, 114 mmol, 90%); this crude material was
distilled (200 mTorr; 90 °C) to afford a colorless oil (23.9 g,
105 mmol): 1H NMR δ 6.95 (m, 2, Hm), 6.84 (m, 1, Hp) 2.53 (s,
2, CH2), 2.08 (s, 6, Meo), 0.04 (s, 6, SiMe).
[Ar 2NP N]Zr Me2. A 3.0 M solution of MeMgBr in ether (306
µL, 0.92 mmol) was added to a stirred slurry of [Ar2NPN]ZrCl2
(300 mg, 0.46 mmol) in diethyl ether (8 mL) at -35 °C. The
reaction mixture was stirred at room temperature for 1 h.
Dioxane was added, and the reaction mixture was stirred for
an additional 20 min. The resulting milky solution was filtered
through Celite. The solvents were removed from the filtrate
in vacuo, and the white crystalline material was freeze-dried
using 4 mL of benzene. The product was obtained in quantita-
tive yield as a white powder (276 mg, 0.45 mmol). No further
purification was necessary, although the complex may be
recrystallized from dichloromethane/pentane mixtures to af-
ford large colorless crystals in 47% yield: 1H NMR δ 7.70 (m,
2, Hp), 7.2-6.9 (m, 4, aryl), 2.38 (s, 3, Meo), 2.26 (s, 3, Meo),
1.21 (m, 4, CH2), 0.88 (d, 3J HP ) 6.6, 3, Meeq), 0.16 (s, 6, SiMe),
P h P (CH2SiMe2NHAr )2. Phenylphosphine (4.9 g, 45 mmol)
and ClCH2SiMe2NH(2,6-Me2C6H3) (20.3 g, 90 mmol) were
dissolved in diethyl ether (120 mL), and the solution was cooled
to -35 °C. A 2.5 M solution of LiBu in hexane (35.6 mL, 90
mmol) was then added at -35 °C. A white precipitate of LiCl
formed immediately. The reaction was stirred overnight at
room temperature, and the solvents were removed in vacuo.
The residue was extracted with pentane (2 × 100 mL), and
LiCl was filtered off through Celite. The solvent was removed
from the filtrate in vacuo to give the product as a pale yellow
oil in quantitative yield: 1H NMR δ 7.58 (m, 2, PhP), 7.05 (m,
3, PhP), 6.96 (m, 2, Hm), 6.85 (m, 1, Hp), 2.08 (s, 6, Meo), 1.06
(m, 2, CH2), 0.04 (s, 6, SiMe), 0.01 (s, 6, SiMe); 13C{1H} δ 144.0,
133.5 (d, 1J CP ) 25), 132.1, 129.9, 129.08, 129.04, 128.96, 122.5,
22.0 (d, 1J CP )19, CH2), 20.5 (s, ArMe), 1.6 (d, 3J CP ) 4.5, SiMe),
3
-0.05 (s, 6, SiMe), -0.24 (d, J HP ) 1.5, 3, Meax); 13C{1H} δ
3
1
1.5 (d, J CP ) 4, SiMe); 31P{1H} δ -36.1. Anal. Calcd for
144.1, 143.9, 138.9, 138.8, 136.6 (d, J CP ) 16), 132.5, 132.3,
2
C
28H41N2PSi2: C, 68.25; H, 8.39; N, 5.68. Found: C, 68.12; H,
130.3, 129.9, 129.6, 129.4, 129.3, 125.1, 46.4 (d, J CP ) 30.1,
2
8.44; N, 5.74.
Meax), 45.0 (d, J CP ) 6.2, Meeq), 22.0 (s, Meo), 21.4 (s, Meo),
1
3
3
[Ar 2NP N]Zr (NMe2)2. H2[Ar2NPN] (3.6 g, 7.3 mmol) was
dissolved in 50 mL of pentane, and Zr(NMe2)4 (2.0 g, 7.3 mmol)
was added as a solid at room temperature. The reaction was
stirred overnight and filtered to remove a small amount of
precipitate. The solvents were removed under reduced pres-
sure to give [Ar2NPN]Zr(NMe2)2 as a white solid in quantita-
tive yield. An analytically pure sample was obtained by
recrystallization from pentane at -35 °C: 1H NMR δ 7.63 (m,
2, PhP), 7.20 (m, 3, PhP), 7.06 (d, 4, Hm), 6.79 (t, 2, Hp), 3.08
(s, 6, NMe2), 2.39 (s, 6, Meo), 2.38 (s, 6, Meo), 1.97 (s, 6, NMe2),
1.26 (m, 4, SiCH2P), 0.18 (s, 6, SiMe), -0.08 (s, 6, SiMe); 31P
NMR δ -27.9. Anal. Calcd for C32H51N4PSi2Zr: C, 57.35; H,
7.67; N, 8.36. Found: C, 57.06; H, 7.45; N, 8.18.
[Ar 2NP N]Zr Cl2. [Ar2NPN]Zr(NMe2)2 (1.64 g, 2.45 mmol)
was dissolved in 50 mL of ether, and a 1.0 M solution of HCl
in ether (4.9 mL, 4.9 mmol) was added by syringe at -35 °C.
The reaction was stirred vigorously for 2 h. The solution was
concentrated to 30 mL and was allowed to stand overnight.
The white crystalline solid that formed was isolated on a frit
18.5 (d, J CP ) 13, CH2), 3.7 (d, J CP ) 5.0, SiMe), 2.9 (d, J CP
) 3.5, SiMe); 31P{1H} δ -23.7. Anal. Calcd for C30H45N2PSi2-
Zr: C, 58.87; H, 7.41; N, 4.58. Found: C, 58.78; H, 7.29; N,
4.58.
[Ar2NPN]Zr(13CH3)2 was prepared similarly: 13C NMR δ
46.0 (2J CP ) 31, J CH ) 113), 45.1 (2J CP ) 6.2, J CH ) 115).
1
1
Ack n ow led gm en t. We thank Exxon Corporation for
supporting this research.
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and structure refinement details, atomic coordinates,
bond lengths and angles, and anisotropic displacement pa-
rameters for [N2P]Zr(CH3)(CH2Ph), [t-Bu2NPN]ZrMeCl, [Ar2-
NPN]ZrMeCl, and {[t-BuNSiMe2CH2P(Ph)CH2SiMe2N]ZrMe}2
(24 pages). Ordering information is given on any current
masthead page.
OM9807654