The reactivity of trimethylsilyliminophosphines towards titanium and zirconium halides

Article abstract of DOI:10.1039/b009082o

Zirconium tetrachloride reacted with C₂H₄(Ph₂P=NSiMe₃)₂-1,2 1 under C-H activation to give the NCN Chelate complex ZrCl₃{κ³-N,C,N′-C₂H₃(Ph ₂P=NSiMe₃)₂}, while the reaction with C₅H₃N(Ph₂P=NSiMe₃)₂-2,6 gave an N-donor adduct. Cp^*TiCl₃ reacts with trimethylsilyliminophosphines under dehalosilylation in all cases. In contrast to 1, the potentially C-N chelating benzylphosphinimine (4-Bu^tC₆H₄CH₂)Ph₂P=NSiMe ₃ undergoes dehalosilylation with TiCl₄ in preference to C-H activation, while prolonged reflux with ZrCl₄ affords the salt [4-Bu^tC₆H₄CH₂P(Ph)₂NHSiMe ₃]₂[Zr₂Cl₁₀]. The molecular structures of the latter, ZrCl₃ {C₂H₃(Ph₂PNSiMe₃)₂}, C₅H₃N(Ph₂P=NTiCl₂Cp^* )₂-2,6, and TiCl₂Cp^* {N=PPh₂CH₂C₆H₄Bu^t-4} have been determined by X-ray diffraction.

Full text of DOI:10.1039/b009082o

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The reactivity of trimethylsilyliminophosphines towards titanium
and zirconium halides
Mark J. Sarsfield,a Musa Said,b Mark Thornton-Pett,a Lee A. Gerrardb and
Manfred Bochmann*b
a School of Chemistry, University of Leeds, Leeds, UK LS2 9JT
b School of Chemical Sciences, University of East Anglia, Norwich, UK NR4 7TJ
Received 13th November 2000, Accepted 31st January 2001
First published as an Advance Article on the web 22nd February 2001
Zirconium tetrachloride reacted with C H (Ph P᎐NSiMe ) -1,2 1 under C–H activation to give the NCN chelate
᎐
2
4
2
3 2
complex ZrCl {κ3-N,C,NЈ-C H (Ph P᎐NSiMe ) }, while the reaction with C H N(Ph P᎐NSiMe ) -2,6 gave an
᎐
᎐
3
2
3
2
3
2
5
3
2
3 2
N-donor adduct. Cp*TiCl3 reacts with trimethylsilyliminophosphines under dehalosilylation in all cases. In
contrast to 1, the potentially C–N chelating benzylphosphinimine (4-ButC H CH )Ph P᎐NSiMe undergoes
᎐
6
4
2
2
3
dehalosilylation with TiCl4 in preference to C–H activation, while prolonged reflux with ZrCl4 affords the salt
[4-ButC6H4CH2P(Ph)2NHSiMe3]2[Zr2Cl10]. The molecular structures of the latter, ZrCl3{C2H3(Ph2PNSiMe3)2},
C H N(Ph P᎐NTiCl Cp*) -2,6, and TiCl Cp*{N᎐PPh CH C H But-4} have been determined by X-ray diffraction.
᎐
᎐
5
3
2
2
2
2
2
2
6
4
those of 2 suggested that the analogous zirconium complex 3
had been formed (Scheme 1). The CH2CH bridge gives rise to a
Introduction
Trimethylsilyl substituted phosphinimines R P᎐NSiMe are
᎐
3
3
known to react with Lewis acidic metal halides to give phos-
phinimido complexes via a dehalosilylation reaction (eqn. 1).1
(1)
(2)
Titanium tris(t-butyl)phosphinimido complexes formed in this
way have proved to be highly active ethene polymerisation
catalysts.2 Alternatively, silyl phosphinimines may simply form
N-donor adducts (eqn. 2), some of which have proved to be
thermally surprisingly stable.1,3 As part of an exploration of
the coordination chemistry of oligodentate P᎐N ligands
᎐
and possible applications to catalysis,4 we recently reported
that 1,2-bis[diphenyl(trimethylsilylimino)phosphoranyl]ethane
1 reacts with TiCl4 not under dehalosilylation and formation
of titanium imido complexes as expected, but undergoes C–H
activation and HCl elimination to give the red-purple complex
2 (eqn. 3).5 We report here on the reaction of 1 and related
Scheme 1
characteristic set of three multiplets in the 1H NMR spectrum,
at δ 1.07 (CH), 2.63 and 2.96, which each show coupling to two
protons and two phosphorus atoms. As is typical for phosphin-
imine N-donor adducts, the 31P NMR chemical shifts are found
at comparatively positive values, at δ 28.5 and 39.1, similar to
those of aminophosphonium salts (e.g. compound 13 below:
δ 40.4).
(3)
Compound 3 retains variable amounts of dichloromethane
of crystallisation. The bulk material analysed for 3ؒCH2Cl2,
while after some attempts of slow recrystallisation from
dichloromethane crystals of 3ؒ2CH2Cl2 were obtained which
proved suitable for X-ray diffraction. The crystal structure (Fig.
1) confirmed the NMR assignments. Selected bond distances
and angles are collected in Table 1. Unfortunately the crystal
suffered from solvent loss during data collection, in addition to
disorder problems (see Experimental section) and did not
give high quality diffraction data. Zirconium is in a distorted
trimethylsilyliminophosphine ligands with TiCl4, ZrCl4 and
Cp*TiCl3 (Cp* = η-C5Me5).
Results and discussion
The reaction of 1,2-bis[diphenyl(trimethylsilylimino)phosphor-
anyl]ethane 1 with ZrCl4 in dichloromethane at room temper-
ature leads to the formation of a poorly soluble white
precipitate. Comparison of the NMR data of this product with
octahedral environment containing
a four- and a five-
membered C–N chelate ring. The Zr–Cl(1) bond trans to the
zirconium–carbon bond is slightly longer [2.477(2) Å] than
822
J. Chem. Soc., Dalton Trans., 2001, 822–827
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b009082o

View Article Online
Table 1 Selected bond length (Å) and angles (Њ)
ZrCl3{C2H3(Ph2᎐᎐NSiMe3)2} 3
Zr(1)–N(1)
Zr(1)–C(1)
Zr(1)–Cl(2)
Zr(1)–Cl(1)
N(1)–Si(1)
P(1)–C(1)
2.201(4)
2.407(11)
2.4580(13)
2.477(2)
1.754(5)
1.771(9)
1.809(5)
Zr(1)–Cl(2Ј)a
N(1)–P(1)
Si(1)–C(13)
P(1)–C(2)
2.4580(13)
1.618(5)
1.863(6)
1.825(10)
1.806(5)
1.527(12)
P(1)–C(121)
C(1)–C(2)a
P(1)–C(11)
N(1)a–Zr(1)–N(1) 145.5(3)
N(1)a–Zr(1)–C(1)
N(1)–Zr(1)–C(1)
C(1)–Zr(1)–Cl(2)
N(1)–Zr(1)–Cl(2)a
N(1)–Zr(1)–Cl(1)
Cl(2)–Zr(1)–Cl(1)
P(1)–N(1)–Zr(1)
N(1)–P(1)–C(1)
82.9(3)
63.2(3)
N(1)–Zr(1)–Cl(2)
90.59(11)
Cl(2)–Zr(1)–Cl(2)a 177.15(10)
101.4(2)
90.25(11)
107.26(14)
88.57(5)
108.4(2)
91.0(4)
C(1)a–Zr(1)–Cl(2)
C(1)–Zr(1)–Cl(1)
P(1)–N(1)–Si(1)
Si(1)–N(1)–Zr(1)
81.4(2)
165.9(2)
126.8(3)
124.7(3)
C(1)–P(1)–C(111) 115.9(4)
C5H3N(Ph2PNTiCl2Cp*)2-2,6 7
Fig. 1 Molecular structure of ZrCl3{Me3SiNP(Ph2)CHCH2P(Ph2)-
NSiMe3} 3, showing the atomic numbering scheme. Ellipsoids
are drawn at 40% probability. Note that the CHCH2 backbone is
disordered 50 : 50 over two positions, one of which is shown.
Ti(1)–N(1)
Ti(1)–Cl(2)
Ti(1)–C(3)
Ti(1)–C(1)
N(1)–P(1)
P(1)–C(111)
C(11)–N(12)
C(13)–P(2)
Ti(2)–Cl(4)
1.794(2)
2.3091(8)
2.345(3)
2.412(3)
1.578(2)
1.804(3)
1.340(3)
1.824(2)
2.3044(9)
Ti(1)–Cl(1)
Ti(1)–C(2)
Ti(1)–C(4)
Ti(1)–C(5)
P(1)–C(121)
P(1)–C(11)
Ti(2)–N(2)
Ti(2)–Cl(3)
N(2)–P(2)
2.2849(8)
2.334(3)
2.377(3)
2.421(3)
1.800(3)
1.823(3)
1.791(2)
2.3116(8)
1.578(2)
the other two Zr–Cl distances [2.4580(13) Å]. By comparison,
the Zr–C(1) distance is long, 2.407(11) Å. As a consequence
of disorder only average Zr–N bond distances can be given,
2.201(4) Å. Both nitrogen atoms in 3 are trigonal planar.
Initial ethene polymerisation attempts with compound 3 in
toluene activated with methylaluminoxane (MAO), (MeAlO)n
(nominal Al : Zr ratio 1000 : 1), showed encouraging activity
(50 ЊC, 1 bar). However, recrystallised 3 proved to be inactive,
and we ascribe the observed catalytic activity to an impurity
which could not be identified.
Cl(1)–Ti(1)–Cl(2) 102.99(3)
P(1)–N(1)–Ti(1) 155.4(2)
N(1)–P(1)–C(111) 112.14(11)
N(1)–P(1)–C(11) 111.69(12)
N(1)–Ti(1)–Cl(1)
N(1)–Ti(1)–Cl(2)
102.40(8)
101.81(8)
N(1)–P(1)–C(121) 113.08(12)
C(16)–C(11)–P(1) 123.0(2)
C(11)–N(12)–C(13) 117.7(2)
N(12)–C(11)–P(1) 114.1(2)
TiCl2Cp*{N᎐PPh2CH2C6H4But-4} 12
᎐
By contrast to the C–H activation leading to compound 3,
the reaction of 1 with Cp*TiCl3 proceeds cleanly with dechloro-
silylation, to give the titanium phosphinimido complex C2H4-
Ti(1)–N(1)
Ti(1)–Cl(2)
N(1)–P(1)
P(1)–C(21)
1.7737(16)
2.3158(5)
1.5841(16)
1.8066(18)
Ti(1)–Cl(1)
P(1)–C(11)
P(1)–C(31)
2.3085(5)
1.8018(19)
1.8170(18)
{Ph P᎐NTiCl Cp*} -1,2
4
as orange-red crystals. The
᎐
2
2
2
1
symmetric structure is evident from the observation in the H
NMR spectrum of a simple doublet for the C2H4 bridge (δ 2.87,
JHP = 2.4 Hz). The linear transoid geometry was confirmed by
X-ray diffraction which allowed the identification of all heavy
atoms, although the data were of insufficient quality to be
discussed here further.
N(1)–Ti(1)–Cl(1)
Cl(1)–Ti(1)–Cl(2) 101.38(2)
P(1)–N(1)–Ti(1)
N(1)–P(1)–C(21)
N(1)–P(1)–C(31)
104.39(5)
N(1)–Ti(1)–Cl(2)
N(1)–P(1)–C(11)
C(11)–P(1)–C(21)
C(11)–P(1)–C(31)
101.21(5)
111.10(9)
108.59(8)
105.75(9)
165.69(11)
111.69(8)
112.74(9)
[4-ButC6H4CH2P(Ph)2NHSiMe3]2[Zr2Cl10] 13
Alkylation of compound 4 with MeMgCl in diethyl ether
leads cleanly to C H {Ph P᎐NTiMe Cp*} -1,2 5. Mixtures of 4
᎐
2
4
2
2
2
Zr(1)–Cl(5)
Zr(1)–Cl(4)
Zr(1)–Cl(3)
Cl(3)–Zr(1)*
P(1)–C(18)
P(1)–C(1)
2.371(2)
2.407(2)
2.615(2)
2.640(2)
1.790(6)
1.823(6)
Zr(1)–Cl(2)
Zr(1)–Cl(1)
Zr(1)–Cl(3)*
P(1)–N(1)
P(1)–C(12)
Si(1)–N(1)
2.388(2)
2.431(2)
2.640(2)
1.635(5)
1.792(6)
1.772(5)
activated with methylaluminoxane (MAO, Al : Ti = 1000 : 1) in
toluene at 60 ЊC under 1 bar ethene show modest polymeris-
ation activity [ca. 5 × 103 g polyethylene (PE) (mol Ti)Ϫ1 hϪ1
barϪ1], while equimolar mixtures of 5 and B(C6F5)3 only gave
traces of polymer.
Dehalosilylation is also observed on exposure of the
Cl(5)–Zr(1)–Cl(2) 100.51(8)
Cl(5)–Zr(1)–Cl(4)
Cl(5)–Zr(1)–Cl(1)
Cl(4)–Zr(1)–Cl(3)
Cl(2)–Zr(1)–Cl(3)
Cl(1)–Zr(1)–Cl(3)
Cl(2)–Zr(1)–Cl(3)*
Cl(1)–Zr(1)–Cl(3)*
93.68(8)
92.54(8)
173.28(7)
169.56(6)
87.75(6)
92.71(6)
86.60(6)
potentially tridentate4 bis(iminophosphino)pyridine C5H3N-
Cl(2)–Zr(1)–Cl(4)
Cl(2)–Zr(1)–Cl(1)
Cl(5)–Zr(1)–Cl(3)
Cl(4)–Zr(1)–Cl(3)
92.09(7)
89.28(7)
89.62(6)
89.74(6)
(Ph P᎐NSiMe ) -2,6 6 to Cp*TiCl in dichloromethane at
᎐
2
3
2
3
room temperature, to give orange crystalline C H N{Ph P᎐
᎐
2
5
3
NTiCl2Cp*}2-2,6ؒCH2Cl2 7ؒCH2Cl2 (Scheme 2). The molecular
structure of 7 is shown in Fig. 2. The molecule contains near-
linear Ti–N–P moieties, with an average Ti–N–P angle of
Cl(5)–Zr(1)–Cl(3)* 166.74(6)
Cl(4)–Zr(1)–Cl(3)* 86.76(7)
Cl(3)–Zr(1)–Cl(3)* 77.12(5)
Zr(1)–Cl(3)–Zr(1)* 102.88(5)
160.5(2)Њ. The Ti–N and P᎐N distances of, on average, 1.793(2)
N(1)–P(1)–C(18)
108.8(3)
N(1)–P(1)–C(12)
N(1)–P(1)–C(1)
C(12)–P(1)–C(1)
111.7(3)
110.5(3)
107.3(3)
᎐
C(18)–P(1)–C(12) 110.3(3)
and 1.578(2) Å, respectively, correspond closely to those found
in the parent complex, CpCl TiN᎐PPh .6 There is no coord-
C(18)–P(1)–C(1)
108.1(3)
᎐
2
3
a
1
ination to the pyridine N atom.
–
Symmetry relation: 1 Ϫ x, ϩy, 2 Ϫ z.
By contrast, the reaction of compound 6 with ZrCl4 under
similar conditions leads to a product analysing for C5H3N-
{Ph P᎐N(SiMe )ZrCl } -2,6ؒ2CH Cl 8ؒ2CH2Cl2. Although
phosphinimines with formation of CPN chelate structures
᎐
2
3
4
2
2
2
crystals suitable for X-ray diffraction could not be grown, the
analogous to those of 2 and 3, the reaction of the benzyl phos-
composition of 8 is confirmed by the NMR spectra, e.g. the 31
P
phinimine 4-ButC H CH P(Ph) ᎐NSiMe 9 with titanium and
᎐
6
4
2
2
3
NMR chemical shift of δ 39.5. Heating 8ؒ2CH2Cl2 to 180 ЊC for
3 h failed to induce dehalosilylation but allowed the recovery of
solvate-free 8.
zirconium halides was explored (Scheme 3). Unlike 1, the reac-
tion of 9 with TiCl4 failed to give a chelate complex of type 10
but led instead to dehalosilylation with formation of 11 as
a poorly soluble orange microcrystalline solid in high yield.
In an attempt to probe the extent of C–H activation of alkyl-
J. Chem. Soc., Dalton Trans., 2001, 822–827
823

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Fig. 2 Molecular structure of C5H3N{Ph2P᎐NTiCl2Cp*}2-2,6, 7.
Fig. 4 Crystal structure of [4-ButC6H4CH2P(Ph)2NHSiMe3]2[Zr2Cl10]
13.
᎐
Fig. 3 Molecular structure of TiCl2Cp*{N᎐PPh2CH2C6H4But-4}ؒ
᎐
C6H5Me 12ؒC6H5Me).
Scheme 3
Scheme 2
to have been crystallographically characterised in only a few
cases.7 Typically, the Zr–Cl distances to the bridging chlorine
atoms are ca. 0.2 Å longer than the terminal Zr–Cl bonds. The
bridge is slightly unsymmetric, with Zr–Cl(3) and Zr–Cl(3*)
bond lengths of 2.615(2) Å and 2.640(2) Å, respectively. There
is no indication for hydrogen bonding between cations and
anion.
There was evidence for a second species in solution, with a
31P NMR shift of δ 31.45, which was suspected to be the metal-
lated compound ZrCl3{4-ButC6H4CHP(Ph)2NSiMe3} 14. The
formation of such a product would provide the HCl required
for the generation of 13 according to eqn. (4), although in view
of the almost 40% yield of 13 hydrolysis by traces of moisture
could not be ruled out. However, the reaction of Li[4-But-
C6H4CHP(Ph)2NSiMe3] with ZrCl4 (eqn. 5) affords a product
with a very similar 31P NMR chemical shift (δ 31.92). Although
Similarly, the reaction of 9 with Cp*TiCl3 affords orange
TiCl Cp*{N᎐PPh CH C H But-4} 12. The structure of 12
᎐
2
2
2
6
4
(Fig. 3) shows a Ti–N bond of 1.7737(16) Å and a near-linear
Ti–N–P arrangement, with an angle of 165.69(11)Њ.
A different course of reaction was followed when compound
9 was treated with ZrCl4. A product derived from dehalosilyl-
ation was not observed. Refluxing the mixture in dichloro-
methane for 5 h followed by crystallisation led to the isolation
of a colourless material which was identified as a salt of
the decachlorodizirconate dianion, [4-ButC6H4CH2P(Ph)2-
NHSiMe3]2[Zr2Cl10] 13, in moderate yield. The compound
shows a 31P NMR signal at δ 40.4, as expected of a phos-
phonium cation. The structure of 13 was confirmed by X-ray
diffraction (Fig. 4). The [Zr2Cl10]2- anion is rare and appears
824
J. Chem. Soc., Dalton Trans., 2001, 822–827

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methane (40 cm3) was stirred at room temperature for 17 h. A
(4)
milky white precipitate developed which was allowed to settle
for 1 h and filtered off. The white residue was washed with
dichloromethane (40 cm3) and dried in vacuo to give 3ؒCH2Cl2,
yield 2.20 g (2.58 mmol, 60%). Crystals suitable for X-ray dif-
fraction were obtained from warm dichloromethane. 1H NMR
(CD2Cl2, 20 ЊC): δ 0.13 (s, 9H, SiMe3), 0.14 (s, 9H, SiMe3), 1.07
(d,d,d,d, 1H, CH, JHH = 14.2, 4.7, JHP = 6.1, 3.5), 2.63 (d,d,d,d,
1H, CH2, JHH = 14.2, 4.7, JHP = 6.0, 1.7), 2.96 (d,d,d,d, 1H,
CH2, JHH = 14.2, 14.2, JHP = 17.4, 10.5 Hz) and 7.93–7.35 (m,
20H, Ph). 13C-{1H} NMR (CD2Cl2, 20 ЊC): δ 2.9 (d, SiMe3,
JCP = 3.3), 3.9 (d, SiMe3, JCP = 3.6), 20.8 (d,d CH, JCP = 71.8,
9.9), 36.0 (d, CH2, JCP = 77.9), 124.7 (d, ipso-C of Ph2,
JCP = 86.9), 125.6 (d, ipso-C of Ph, JCP = 90.3), 129.0 (d, m-C of
Ph, JCP = 12.4), 129.1 (d, m-C of Ph, JCP = 11.5), 129.2 (d, m-C
of Ph, JCP = 12.7), 129.3 (d, m-C of Ph, JCP = 12.7), 131.0
(d, o-C of Ph, JCP = 10.4), 132.1 (d, p-C of Ph, JCP = 3.0), 132.8
(d, p-C of Ph, JCP = 3.0), 133.3 (d, p-C of Ph, JCP = 2.0), 133.4
(d, p-C of Ph, JCP = 2.2), 133.4 (d, o-C of Ph, JCP = 10.4), 133.7
(d, o-CofPh, JCP = 10.6), 134.0(d, o-CofPh, JCP = 9.8)and136.2
(d,d, ipso-C of Ph, JCP = 80.1, 1.8 Hz). 31P NMR (CD2Cl2,
20 ЊC): δ 28.5 (d, JPP = 81.9) and 39.1 (d, JPP = 81.9 Hz). Calc.
for C32H41Cl3N2P2Si2ZrؒCH2Cl2: C, 46.4; H, 5.1; N, 3.3%.
Found: C, 47.0; H, 5.3; N, 3.8%.
an analytically pure sample of 14 could not be obtained, the
spectroscopic data are in agreement with the suggested struc-
ture. Similarly, the reaction of Li[4-ButC6H4CHP(Ph)2NSiMe3]
with TiCl4 gives TiCl3{4-ButC6H4CHP(Ph)2NSiMe3} 10 men-
tioned earlier; the compound was isolated as a light yellow
powder.
(5)
C H {Ph P᎐NTiCl Cp*} -1,2 4. A solution of compound 1
᎐
2
4
2
2
2
(0.50 g, 1.73 mmol) and Cp*TiCl3 (1.00 g, 3.45 mmol) in
dichloromethane (30 cm3) was stirred at room temperature for
16 h. The solution was filtered, reduced in volume (ca. 20 cm3)
and placed in the freezer overnight. Bright orange-red crystals
of C H {Ph P᎐NTiCl Cp*} -1,2 4 were isolated, yield 1.45 g
᎐
2
4
2
2
2
1
(1.55 mmol, 90%). H NMR (CD2Cl2, 20 ЊC): δ 1.98 (s, 30 H,
Cp*), 2.87 (d, 4H, CH2, JHP = 2.4 Hz), 7.50 (m, 8H, o-H of Ph),
7.58 (m, 4H, p-H of Ph) and 7.78 (m, 8H, m-H of Ph). 13C
NMR (CD2Cl2, 20 ЊC): δ 12.1 (s, C5Me5), 22.7 (vt, 2CH2,
JCP = 31.7), 127.2 (s, C5Me5), 129.0 (t, o-C of Ph, JCP = 6.4),
129.8 (d, ipso-C of Ph, JCP = 97.9), 132.9 (d, m-C of Ph,
JCP = 5.3 Hz) and 132.4 (s, p-C of Ph). 31P NMR (CD2Cl2,
20 ЊC): δ 6.6. Calc. for C23H27Cl2NPTi: C, 59.1; H, 5.8; Cl, 15.2;
N, 3.0%. Found: C, 58.8; H, 5.8; Cl, 15.0; N, 3.2%.
Conclusion
Chelating bis(trimethylsilylimino)phosphines undergo C–H
activation in preference to dehalosilylation with both titanium
and zirconium tetrachloride, to give products containing
[C–N]Ϫ chelate rings. In all other cases ZrCl4 forms N-donor
adducts or salts. The (phosphinimine)ZrCl4 complexes are
thermally stable and cannot be converted into dehalosilylation
products. By contrast, TiCl4 shows a preference for dehalo-
silylation to give phosphinimido complexes, a reaction pathway
that is exclusively followed by the less Lewis acidic Cp*TiCl3.
C H {Ph P᎐NTiMe Cp*} -1,2 5. This compound was pre-
᎐
2
4
2
2
2
pared from 1 (0.50 g, 1.73 mmol) and Cp*TiCl3 (1.00 g, 3.45
mmol) in a one-pot procedure. A dichloromethane solution of 4
was prepared as described above and the solvent replaced by thf
(30 cm3). The solution was cooled to Ϫ78 ЊC and treated with
MeMgCl (2.6 cm3, 6.9 mmol, 3 M solution in thf). The orange
suspension slowly turned pale yellow on warming to room tem-
perature. After 3 h the solvent was removed and the product
extracted into 50 : 50 toluene–light petroleum (2 × 30 cm3). The
combined extracts were cooled to Ϫ20 ЊC overnight to afford 5
as a crystalline material (0.35 g, 24%). 1H NMR (C6D6, 20 ЊC):
δ 0.63 (s, 12H, TiMe), 1.95 (s, 30 H, Cp*), 3.01 (d, 4H, 2CH2,
J = 2.0 Hz), 7.02 (m, 12H, o,p-H of Ph) and 7.85 (m, 8H, m-H
of Ph). 13C NMR (C6D6, 20 ЊC): δ 12.0 (s, C5Me5), 24.5 (“t”,
2CH2, JCP = 32.1), 43.2 (TiMe), 119.3 (s, C5Me5), 129.0 (t, o-C
of Ph, JCP = 5.7), 131.5 (d, m-C of Ph, JCP = 4.5), 131.7 (s, p-C
of Ph) and 134.0 (d, ipso-C of Ph, JCP = 95.0 Hz). 31P NMR
(C6D6, 20 ЊC): δ Ϫ6.6. Calc. for C25H33NP2Ti: C, 70.4; H, 7.8; N,
3.3%. Found: C, 70.3; H, 8.0; N, 3.0%.
The potentially tridentate ligand C H (Ph P᎐NSiMe ) -1,2 1
᎐
2
4
2
3 2
has a significantly greater tendency towards C–H activation
than monoiminophosphines; the latter require lithiation to give
[C–N]Ϫ chelate complexes.
Experimental
All manipulations were performed under
a dinitrogen
atmosphere unless specified using Schlenk techniques. Solvents
were distilled under N2 over sodium–benzophenone (thf),
sodium (toluene), sodium–potassium alloy [diethyl ether, light
petroleum (bp 40–60 ЊC)], or CaH2 (dichloromethane). NMR
solvents were dried over activated molecular sieves and
degassed through several freeze–thaw cycles. NMR spectra
were recorded on Bruker DPX300 or DRX500 spectrometers.
Chemical shifts are reported in ppm and referenced to residual
solvent resonances (1H, 13C) or to external 85% H3PO4 (31P).
Bis(diphenylphosphino)methane (dppm), azidotrimethylsilane
and 2,6-difluoropyridine were used as purchased, ZrCl4 was
freshly sublimed under nitrogen before use (400–450 ЊC, 1
C H N{Ph P᎐NTiCl Cp*} -2,6 7.
A solution of C5H3-
᎐
5
3
2
2
2
N(Ph P᎐NSiMe ) -2,6 64 (1.07 g, 1.73 mmol) and Cp*TiCl3
atm), Cp*TiCl3,8 C H (Ph P᎐NSiMe ) -1,2 19 and C5H3N-
᎐
2
3 2
᎐
2
4
2
3 2
(1.00 g, 3.45 mmol) in dichloromethane (30 cm3) was stirred at
room temperature for 16 h. The solution was filtered, reduced
in volume to ca. 20 cm3 and placed in a freezer overnight. Bright
(Ph P᎐NSiMe ) -2,6 64 were prepared according to literature
᎐
2
3 2
procedures.
orange crystals of C H N{Ph P᎐NTiCl Cp*} -2,6ؒCH Cl
᎐
5
3
2
2
2
2
2
Preparations
7ؒCH2Cl2 were isolated, yield 1.49 g (1.40 mmol, 81%). 1H
NMR (CD2Cl2, 20 ЊC): δ 1.97 (s, 30 H, C5Me5), 7.33 (m, 8H,
o-H of Ph), 7.53 (m, 12H, m,p-H of Ph), 8.17 (m, 1H, p-H of
ZrCl3{CHCH2(Ph2PNSiMe3)2} 3. A mixture of compound 1
(2.50 g, 4.36 mmol), ZrCl4 (1.00 g, 4.29 mmol) and dichloro-
J. Chem. Soc., Dalton Trans., 2001, 822–827
825

View Article Online
Table 2 Crystal data of iminophosphorane complexes
3ؒ2CH2Cl2
7
12
13
Formula
M
C32H41Cl3N2P2Si2Zrؒ2CH2Cl2
939.21
C50H55Cl6N3P2Ti2
1068.41
C40H48Cl2NPTi
692.56
C52H70Cl10N2P2Si2Zr2
1374.13
Crystal system
Space group
Monoclinic
C2/c
Triclinic
P1
Monoclinic
P21/n
Monoclinic
P21/n
¯
a/Å
b/Å
c/Å
α/Њ
22.6760(10)
9.5021(5)
21.3807(7)
12.0929(2)
13.4161(4)
16.3861(4)
84.4990(14)
80.911(2)
81.787(2)
2590.85(11)
2
19.5778(5)
10.3318(3)
19.8983(4)
16.729(3)
11.509(2)
17.448(4)
β/Њ
113.031(3)
112.136(2)
98.13(3)
γ/Њ
U/Å3
4239.7(3)
4
0.86
3728.24(16)
4
0.444
3325.5(11)
2
0.832
Z
µ/mmϪ1
0.716
Independent/
observed reflections
Rint
4113/3582
0.0491
10152/8694
0.0595
7286/6403
0.0627
5572/3623
0.0422
a
R1 [I > 2σ(I)]
wR2 (all data)
0.0661
0.1472
0.0484
0.1314
0.0427
0.1193
0.0544
0.2193
2
a Σ|Fo2 Ϫ Fo2 (mean)|/ΣFo .
py) and 8.79 (m, 2H, m-H of py). 13C NMR (CD2Cl2, 20 ЊC):
δ 13.0 (s, C5Me5), 127.9 (s, C5Me5), 128.8 (d, o-C of Ph,
JCP = 13.6), 130.3 (d, ipso-C of Ph, JCP = 101.1), 131.4 (d,d, m-C
of py, JCP = 21.9, 3.0), 132.6 (s, p-C of Ph), 132.9 (d, m-C of Ph,
JCP = 10.6), 137.8 (t, p-C of py, JCP = 8.7) and 156.2 (d,d, ipso-C
of py, JCP = 128.3, 18.1 Hz). 31P NMR (CD2Cl2, 20 ЊC): δ Ϫ5.2.
Calc. for C49H53Cl4N3P2Ti2ؒCH2Cl2: C, 56.2; H, 5.2; N, 3.9%.
Found: C, 56.0; H, 5.2; N, 3.4%.
cm3, 1.02 mmol) over a period of 10 min. The solution was
warmed to ambient temperature, stirred for 2 h, and added
dropwise to a cold (Ϫ70 ЊC) solution of TiCl4 (0.19 g, 1.02
mmol) in toluene (20 cm3). After warming to room temperature
and stirring for 2 h the mixture was filtered. The filtrate was
concentrated to 10 cm3 and 10 cm3 of light petroleum were
added to give a light yellow powdery solid, yield 0.28 g (0.49
1
mmol, 48%). H NMR (CD2Cl2, 20 ЊC): δ 0.29 (s, 9H, SiMe3),
1.06(s, 9H, CMe3), 3.65 (br, H, CH) and 6.91–7.70 (m, 14H,
C H N{Ph P᎐N(SiMe )ZrCl } -2,6 8. A mixture of ZrCl
Ph). 31P NMR (CD2Cl2, 20 ЊC): δ 5.14.
᎐
5
3
2
3
4
2
4
(0.376 g, 1.607 mmol) and compound 6 (0.500 g, 0.834 mmol)
in dichloromethane (20 cm3) was heated at 40 ЊC for 30 min and
left to stir at room temperature for 16 h. Some solid precipitate
was removed by filtration. The filtrate was concentrated to pro-
TiCl {4-ButC H CH P(Ph) ᎐N} 11. To a solution of com-
᎐
3
6
4
2
2
pound 9 (1.10 g, 2.62 mmol) in toluene (30 cm3) at Ϫ78 ЊC was
added dropwise a solution of TiCl4 (0.50 g, 2.62 mmol) in tolu-
ene (3.5 cm3) over a period of 10 min. The resulting light orange
solution was allowed to warm to ambient temperature and
stirred for 3 h. Solvent was reduced to 5 cm3 and light petrol-
eum (30 cm3) added to yield an orange precipitate which was
collected and dried overnight under vacuum, yield 1.90 g (3.8
vide C H N{Ph P᎐N(SiMe )ZrCl } -2,6ؒ2CH Cl 8ؒ2CH2Cl2,
᎐
5
3
2
3
4
2
2
2
yield 0.65 g (0.6 mmol, 72%). Heating this compound at 180 ЊC
for 3 h gave unsolvated 8 only. 1H NMR (CD2Cl2, 20 ЊC): δ 0.40
(s, 18 H, SiMe3), 7.70 (m, 12H, o- and p-H of Ph), 7.95 (m, 2H,
m-H of py), 8.12 (m, 8H, m-H of Ph) and 8.61 (m, 1H, p-H of
py). 13C NMR (CD2Cl2, 20 ЊC): δ 4.8 (SiMe3), 124.1 (d, ipso-C
of Ph, JCP = 96.6), 130.4 (d, o-C of Ph, JCP = 13.6), 133.1 (d,d,
m-C of py, JCP = 21.1, 2.3), 134.1 (d, m-C of Ph, JCP = 12.1),
135.5 (d, p-C of Ph, JCP = 3.0), 145.2 (t, p-C of py, JCP = 9.1)
and 158.1 (d,d, ipso-C of py, JCP = 122.3, 11.3 Hz). 31P NMR
(CD2Cl2, 20 ЊC): δ 39.5. 8ؒ2CH2Cl2. Calc. for C35H41Cl8-
N3P2Si2Zr2ؒ2CH2Cl2: C, 36.9; H, 3.7; Cl, 30.2; N, 3.6%. Found:
C, 37.0; H, 3.6; Cl, 30.4; N, 3.4%. 8. Calc. for C35H41Cl8-
N3P2Si2Zr2: C, 38.6; H, 3.8; Cl, 26.1; N, 3.9%. Found: C, 38.0;
H, 3.8; Cl, 26.6; N, 4.1%.
1
mmol, 84%). H NMR (C6D6, 20 ЊC): δ 1.14 (s, 9H, CMe3),
3.16 (d, JHP = 13.21 Hz, 2H, CH2) and 6.93–7.53 (m, 14H, Ph).
13C-{1H} NMR (C6D6, 20 ЊC): δ 31.01 (s, CMe3), 34.28 (s,
CMe3), 36.11 (d, JCP = 60.4 Hz, CH2) and 124.83–151.11 (aryl).
31P NMR (C6D6, 20 ЊC, 121.49 MHz): δ 11.6. Calc. for C23H25-
Cl3NPTi: C, 55.2; H, 5.0; N, 2.8%. Found: C, 54.5; H, 5.3; N,
2.9%.
TiCl Cp*{N᎐PPh CH C H But-4}ؒC H Me 12ؒC H Me. A
᎐
2
2
2
6
4
6
5
6
5
solution of compound 9 (1.45 g, 3.46 mmol) and Cp*TiCl3
(1.0 g, 3.46 mmol) in toluene (20 cm3) was heated at 110 ЊC
overnight. The mixture was concentrated to 5 cm3 and light
petroleum added to yield an orange precipitate which was
purified by recrystallisation from hot toluene (1 g cmϪ3) to yield
crystals of 12ؒC6H5Me after 3 h, yield 1.7 g (2.45 mmol, 71%).
1H NMR (C6D6, 20 ЊC): δ 1.13(s, 9H, CMe3), 2.07(s, 15H,
C5Me5), 2.13(s, 3H, Me of toluene), 3.16 (d, JHP = 14.2 Hz, 2H,
CH2) and 6.99–7.90 (m, 19H, aryl). 13C-{1H} NMR (C6D6,
20 ЊC): δ 12.85 (s, 5C, C5Me5), 21.17 (s, 1C, Me of toluene),
31.06 (s, 3C, CMe3), 34.14 (s, 1C, CMe3), 37.04 (d, JCP = 64.1
Hz, CH2) and 125.39–149.70 (aryl). 31P NMR (C6D6, 20 ЊC):
δ 2.5. Calc. for C33H38Cl2NPTiؒC7H8: C, 69.4; H, 7.0; Cl, 10.2;
N, 2.0%. Found: C, 69.5; H, 7.0; Cl, 10.3; N, 1.3%.
4-ButC H CH P(Ph) ᎐NSiMe 9. To a solution of freshly dis-
᎐
6
4
2
2
3
tilled 4-ButC6H4CH2PPh2 (3.20 g, 9.64 mmol) in toluene (50
cm3) was added trimethylsilyl azide (2.78 g, 24.10 mmol) at
room temperature. The mixture was heated to reflux for 18 h,
the volatiles were removed, and light petroleum was added (ca.
30 cm3). Crystals were grown at Ϫ25 ЊC over a period of two
days, yield 2.5 g (6.0 mmol, 62%). 1H NMR (C6D6, 20 ЊC,
300.13 MHz): δ 0.43 (s, 9H, SiMe3), 1.23 (s, 9H, CMe3), 3.46 (d,
JHP = 13.1 Hz, 2H, CH2) and 7.11–7.71 (m, 14H, Ph). 13C-{1H}
NMR (C6D6, 20 ЊC, 75.46 MHz): δ 4.34 (s, 3C, SiMe3), 31.16 (s,
3C, CMe3), 34.13 (s, CMe3), 39.04 (d, JCP = 68.7 Hz, CH2) and
124.98–149.09 (aryl). 31P NMR (C6D6, 20 ЊC, 121.49 MHz):
δ Ϫ0.8. Calc. for C26H34NPSi: C, 74.4; H, 8.2; N, 3.3%. Found:
C, 74.5; H, 8.4; N, 3.3%.
[4-ButC6H4CH2P(Ph)2NHSiMe3]2[Zr2Cl10] 13. A mixture of
compound 9 (1.00 g, 2.38 mmol) and ZrCl4 (0.55 g, 2.38 mmol)
in 30 cm3 of dichloromethane was heated to reflux for 5 h. After
reducing the solvent volume to 5 cm3 the solution was cooled to
4 ЊC for three days to give colourless crystals of 13, yield 0.65 g
TiCl {4-ButC H CHP(Ph) ᎐NSiMe } 10. In a one-pot pro-
᎐
3
6
4
2
3
cedure, to a solution of compound 9 (0.43 g, 1.02 mmol) in
toluene (20 cm3) was added dropwise at Ϫ78 ЊC BunLi (0.64
826
J. Chem. Soc., Dalton Trans., 2001, 822–827

View Article Online
(0.47 mmol, 39%). 1H NMR (thf-d8, 20 ЊC): δ 0.06 (s, 9H,
SiMe3), 1.25 (s, 9H, CMe3), 4.04 (br, 2H, CH2), 4.99 (br, 1H,
NH) and 6.97–7.84 (m, 14H, aryl). 13C-{1H} NMR (thf-d8,
20 ЊC): δ 2.55 (s, 3C, SiMe3), 31.00 (s, CMe3), 32.92 (d,
JCP = 60.1 Hz, CH2), 36.64 (s, CMe3) and 121.82–151.14 (aryl).
31P NMR (thf-d8, 20 ЊC): δ 40.4. Calc. for C26H35Cl5NPSiZr: C,
45.3; H, 5.2; Cl, 25.0; N, 20%. Found: C, 45.2; H, 5.2; Cl, 26.2;
N, 1.9%. The mother liquor showed an additional peak in the
31P NMR spectrum at δ 31.45 (see text).
CCDC reference numbers 154069–154072.
See http://www.rsc.org/suppdata/dt/b0/b009082o/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
This work was supported by BP Amoco Chemicals Ltd.,
Sunbury, and the Engineering and Physical Sciences Research
Council.
ZrCl {4-ButC H CHP(Ph) ᎐NSiMe } 14. Following the pro-
᎐
3
6
4
2
3
References
cedure described for 10, the compound was prepared from
9 (1.5 g, 3.57 mmol) BunLi (2.23 cm3, 3.57 mmol), and ZrCl4
1 Reviews: K. Dehnicke, M. Krieger and W. Massa, Coord. Chem.
Rev., 1999, 182, 19; K. Dehnicke and F. Weller, Coord. Chem. Rev.,
1997, 158, 103.
2 D. W. Stephan, J. C. Steward, F. Guérin, R. E. v. H. Spence, W. Xu
and D. G. Harrison, Organometallics, 1999, 18, 1116; D. W. Stephan,
F. Guérin, R. E. v. H. Spence, L. Koch, X. Gao, S. J. Brown,
J. W. Swabey, Q. Wang, W. Xu, P. Zoricak and D. G. Harrison,
Organometallics, 1999, 18, 2046; C. A. Carraz and D. W. Stephan,
Organometallics, 2000, 19, 3791.
3 M. Grün, F. Weller and K. Dehnicke, Z. Anorg. Allg. Chem.,
1997, 623, 224; C. M. Ong, P. McKarns and D. W. Stephan,
Organometallics, 1999, 18, 4197.
4 S. Al-Benna, M. J. Sarsfield, M. Thornton-Pett, D. L. Ormsby,
P. J. Maddox, P. Brès and M. Bochmann, J. Chem. Soc., Dalton
Trans., 2000, 4247.
5 M. J. Sarsfield, M. Thornton-Pett and M. Bochmann, J. Chem. Soc.,
Dalton Trans., 1999, 3329.
6 I. A. Latham, G. J. Leigh and G. Huttner, J. Chem. Soc., Dalton
Trans., 1986, 377. For related titanium phosphinimido complexes as
bidentate ligands see also: K. V. Katti and R. G. Cavell, Inorg. Chem.,
1989, 28, 413; K. V. Katti and R. G. Cavell, Organometallics, 1991,
10, 539.
7 J. Eicher, U. Müller and K. Dehnicke, Z. Anorg. Allg. Chem., 1985,
521, 37; F. Calderazzo, P. Pallavicini, G. Pampaloni and P. F.
Zanazzi, J. Chem. Soc., Dalton Trans., 1990, 2743; S. J. Coles,
M. B. Hursthouse, D. G. Kelly and N. M. Walker, Acta Crystallogr.,
Sect. C, 1999, 55, 1789.
8 G. Hidalgo-Llinás, M. Mena, F. Palacios, P. Royo and R. Serrano,
J. Organomet. Chem., 1988, 340, 37.
1
(0.83 g, 3.57 mmol). H NMR (CD2Cl2, 20 ЊC): δ 0.38 (s, 9H,
SiMe3), 1.31(s, 9H, CMe3), 3.39 (d, JHP = 13.3 Hz, 1H, CH) and
6.92–7.65 (m, 14H, Ph). Major 31P NMR (CD2Cl2, 20 ЊC,
121.49 MHz): δ 31.92. Unidentified by-products were also
apparent in the spectra which could not be removed.
X-Ray crystallography
In each case a suitable crystal was coated in an inert perfluoro-
polyether oil and mounted in a nitrogen stream at 150 K on a
Nonius Kappa CCD area-detector diffractometer. Data collec-
tion was performed using Mo-Kα radiation (λ = 0.71073 Å)
with the CCD detector placed 30 mm from the sample via a
mixture of 1Њ ꢀ and ω scans at different θ and κ settings using
the program COLLECT.10 The raw data were processed to
produce conventional data using the program DENZO-SMN.11
The datasets were corrected for absorption using the program
SORTAV.12 All structures were solved by heavy-atom methods
using SHELXS 9713 and refined by full-matrix least squares (on
F2) using SHELXL 97.14 All non-hydrogen atoms were refined
with anisotropic displacement parameters. Hydrogen atoms
were constrained to idealised positions. Crystallographic data
for compounds 3, 7, 12 and 13 are summarised in Table 2.
Crystals of 3, which also contain a molecule of CH2Cl2 solvent
per asymmetric unit, proved to be highly efflorescent and were
therefore of limited quality. In addition, molecular C2 crystal-
lographic symmetry introduces a 50 : 50 disorder into the
CH2CH backbone of the ligand of this structure. Only one of
the two positions is shown in Fig. 1. Rigid-bond restraints were
applied to the thermal parameters of the carbon atoms involved
in the disorder.
9 R. Appel and I. Ruppert, Z. Anorg. Allg. Chem., 1974, 406, 131.
10 COLLECT, data collection software, Nonius B. V., Delft, 1999.
11 Z. Otwinowski and W. Minor, Methods Enzymol., 1996, 276,
307.
12 R. H. Blessing, Acta Crystallogr., Sect. A, 1995, 51, 33.
13 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
14 G. M. Sheldrick, SHELXL 97, Program for crystal structure
refinement, University of Göttingen, 1997.
J. Chem. Soc., Dalton Trans., 2001, 822–827
827