Synthesis of titanium complexes that contain triamido-amine ligands

Article abstract of DOI:10.1021/om9508389

We report the synthesis of a variety of titanium complexes that contain (Et₃SiNCH₂CH₂)₃N, (C₆F₅NCH₂CH₂)₃N, or (Me₃SiNCH₂CH₂CH₂)₃N ligands. Complexes in the first category include [(Et₃SiNCH₂CH₂)₃N]TiCl, [(Et₃SiNCH₂CH₂)₃N]Ti(OTf), and [(Et₃SiNCH₂CH₂)₃N]Ti-(t-Bu). Complexes in the second category include [(C₆F₅NCH₂CH₂)₃N]TiX (X = Cl, Br, I, OTf) and [(C₆F₅NCH₂CH₂)₃N]TiR (R = Me, Et). Complexes in the third category include [(Me₃SiNCH₂CH₂CH₂)₃N]TiCl and [(Me₃SiNCH₂CH₂CH₂) ₃N]TiCH₃. In an X-ray study [(Me₃-SiNCH₂CH₂CH₂) ₃N]TiCl was shown to contain a coordinated amino nitrogen and TiN₂C₃ rings that were puckered in a pseudocyclohexane chair form. The TiN₂C₃ rings are proposed to "flip" via dissociation of the amino nitrogen donor in the methyl complex, but the flipping rate is slow on the NMR time scale in [(Me₃SiNCH₂CH₂CH₂)₃N]TiCl as a consequence of the greater electrophilicity of the metal.

Full text of DOI:10.1021/om9508389

1470
Organometallics 1996, 15, 1470-1476
Syn th esis of Tita n iu m Com p lexes Th a t Con ta in
Tr ia m id o-Am in e Liga n d s
Richard R. Schrock,* Christopher C. Cummins, Thomas Wilhelm, Shirley Lin,
Steven M. Reid, Moshe Kol, and William M. Davis
Department of Chemistry, Room 6-331, Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139
Received October 23, 1995X
We report the synthesis of a variety of titanium complexes that contain (Et3SiNCH2CH2)3N,
(C6F5NCH2CH2)3N, or (Me3SiNCH2CH2CH2)3N ligands. Complexes in the first category
include [(Et3SiNCH2CH2)3N]TiCl, [(Et3SiNCH2CH2)3N]Ti(OTf), and [(Et3SiNCH2CH2)3N]Ti-
(t-Bu). Complexes in the second category include [(C6F5NCH2CH2)3N]TiX (X ) Cl, Br, I,
OTf) and [(C6F5NCH2CH2)3N]TiR (R ) Me, Et). Complexes in the third category include
[(Me3SiNCH2CH2CH2)3N]TiCl and [(Me3SiNCH2CH2CH2)3N]TiCH3. In an X-ray study [(Me3-
SiNCH2CH2CH2)3N]TiCl was shown to contain a coordinated amino nitrogen and TiN2C3
rings that were puckered in a pseudocyclohexane chair form. The TiN2C3 rings are proposed
to “flip” via dissociation of the amino nitrogen donor in the methyl complex, but the flipping
rate is slow on the NMR time scale in [(Me3SiNCH2CH2CH2)3N]TiCl as a consequence of
the greater electrophilicity of the metal.
In tr od u ction
A transition metal that is useful in initial studies
involving multidentate amido ligands is titanium. For
example, we reported the synthesis of [(Me3SiNCH2-
CH2)3N]TiCl and some of its alkyl derivatives,2 as well
as trigonal monopyramidal Ti[(t-BuMe2SiNCH2CH2)3N],4
while others have reported ethyl- and isopropyl-substi-
tuted titanium derivatives.9 We found that the reaction
between [(Me3SiNCH2CH2)3N]TiCl and lithium reagents
yielded highly soluble titanium n-Bu and s-Bu com-
plexes and that the s-Bu titanium complex cleanly
eliminates butenes and dihydrogen upon heating to give
a metallacycle (eq 1) that we presume to be related to
A variety of compounds that contain ligands of the
type [(RNCH2CH2)3N]3- (R ) alkyl, trialkylsilyl, C6F5)
have been reported in the last few years.1-14 These
trianionic ligands give rise to relatively rigid trigonal
bipyramidal transition metal complexes when they
behave as tetradentate ligands (i.e., when the amino
nitrogen binds in an apical position) in which chemistry
can be restricted to one apical site. When R is a
sterically bulky group, then rarely observed types of
complexes can be prepared, e.g., a tantalum phosphin-
idene,6 a tungsten alkylidene hydride complex,15 or
tungsten or molybdenum terminal phosphido com-
plexes.16 Complexes that do not have a ligand in the
other apical site, so-called trigonal monopyramidal
species,4 have also been prepared for first-row metals
(Ti-Fe).
X Abstract published in Advance ACS Abstracts, February 1, 1996.
(1) Naiini, A. A.; Menge, W. M. P. B.; Verkade, J . G. Inorg. Chem.
1991, 30, 5009.
(2) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Organometallics
1992, 11, 1452.
(3) Plass, W.; Verkade, J . G. J . Am. Chem. Soc. 1992, 114, 2275.
(4) Cummins, C. C.; Lee, J .; Schrock, R. R. Angew. Chem., Int. Ed.
Engl. 1992, 31, 1501.
(5) Plass, W.; Verkade, J . G. Inorg. Chem. 1993, 32, 3762.
(6) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 756.
(7) Kol, M.; Schrock, R. R.; Kempe, R.; Davis, W. M. J . Am. Chem.
Soc. 1994, 116, 4382.
(8) Shih, K.-Y.; Totland, K.; Seidel, S. W.; Schrock, R. R. J . Am.
Chem. Soc. 1994, 116, 12103.
(9) Schubart, M.; O’Dwyer, L.; Gade, L. H.; Li, W.-S.; McPartlin,
M. Inorg. Chem. 1994, 33, 3893.
(10) Shih, K.-Y.; Schrock, R. R.; Kempe, R. J . Am. Chem. Soc. 1994,
116, 8804.
(11) Freundlich, J .; Schrock, R. R.; Cummins, C. C.; Davis, W. M.
J . Am. Chem. Soc. 1994, 116, 6476.
others that are known for titanium.17 The metallacycle
is also formed upon treating the s-Bu complex with
dihydrogen (25 °C, 12 h, 3 atm). (Only butane is
produced in this reaction.) A resonance that appears at
δ 8.29 in the proton NMR spectrum during the reaction
with dihydrogen in a sealed NMR tube was tentatively
assigned to a titanium(IV) monohydride intermediate.
Therefore it was proposed that the reaction with dihy-
drogen proceeds via hydrogenolysis of the sec-butyl
ligand to give unstable [(Me3SiNCH2CH2)3N]TiH, which
loses dihydrogen to give the cyclometalated product.
This reaction is analogous to the cyclometalation ob-
served in complexes of the type HM[N(SiMe3)2]3 (M )
Th, U).18
(12) Cummins, C. C.; Schrock, R. R. Inorg. Chem. 1994, 33, 395.
(13) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Inorg. Chem.
1994, 33, 1448.
(14) Duan, Z.; Verkade, J . G. Inorg. Chem. 1995, 34, 1576.
(15) Schrock, R. R.; Shih, K.-Y.; Dobbs, D.; Davis, W. M. J . Am.
Chem. Soc. 1995, 117, 6609.
We became interested in preparing other types of
[(RNCH2CH2)3N]Ti complexes in order to determine if
(16) Zanetti, N. C.; Schrock, R. R.; Davis, W. M. Angew. Chem., Int.
Ed. Engl. 1995, 34, 2044.
(17) Simpson, S. J .; Andersen, R. A. Inorg. Chem. 1981, 20, 3627.
(18) Simpson, S. J .; Andersen, R. A. Inorg. Chem. 1981, 20, 2991.
0276-7333/96/2315-1470$12.00/0 © 1996 American Chemical Society

Ti Complexes Containing Triamido-Amine Ligands
Organometallics, Vol. 15, No. 5, 1996 1471
cyclometalation could be prevented and a rare19-21
monomeric Ti(IV) hydride isolated. In this paper we
report the synthesis of a variety of titanium complexes
that contain triethylsilyl- or pentafluorophenyl-substi-
tuted triamido-amine ligands, along with examples of
compounds that contain the new (Me3SiNCH2CH2-
CH2)3N ligand. Complete synthetic procedures for the
(Me3SiNCH2CH2)3N complexes that were reported in a
preliminary fashion2 are also included here, as no
further studies were carried out.
at 85 °C). When [(Et3SiNCH2CH2)3N]Ti(t-Bu) is allowed
to decompose in C6D6 in the absence of any trapping
agent, resonances attributable to a cyclometalated
complex are observed before formation of [(Et3SiNCH2-
CH2)3N]TiH is complete. Therefore loss of isobutylene
from [(Et3SiNCH2CH2)3N]Ti(t-Bu) is too slow for this
reaction to serve as a synthetic route to [(Et3SiNCH2-
CH2)3N]TiH. When [(Et3SiNCH2CH2)3N]Ti(t-Bu) is al-
lowed to decompose in the presence of ethylene (∼10
equiv), resonances consistent with the formation of [(Et3-
SiNCH2CH2)3N]Ti(Et) also can be observed in the proton
NMR spectrum, although [(Et3SiNCH2CH2)3N]TiH can
be observed during the course of the reaction. We
conclude from these experiments that [(Et3SiNCH2-
CH2)3N]TiH resists cyclometalation to a much greater
degree than does [(Me3SiNCH2CH2)3N]TiH and that it
might be isolable, at least at low temperatures, if a route
to it can be devised. Unfortunately no route has yet
been found.
Triflate complexes are potentially useful in chemistry
involving triamido-amine complexes.7 The triflate
complex, [(Et3SiNCH2CH2)3N]Ti(OTf), could be prepared
via a two-step route. [(Et3SiNCH2CH2)3N]TiCl could be
reduced by sodium amalgam to an oily blue complex
that by analogy with isolated [(t-BuMe2SiNCH2CH2)3-
N]Ti4 we believe to be [(Et3SiNCH2CH2)3N]Ti. Subse-
quent oxidation of [(Et3SiNCH2CH2)3N]Ti by ferroceni-
um triflate yields crystalline, yellow-orange [(Et3SiNC-
H2CH2)3N]Ti(OTf) in an overall yield of ∼80%. At-
tempts to prepare [(Et3SiNCH2CH2)3N]Ti(OTf) by treat-
ing [(Et3SiNCH2CH2)3N]TiCl with silver triflate were
not successful.
Resu lts
Syn th esis of [(Et3SiNCH2CH2)3N]Ti Com p lexes.
Crystalline [(Et3SiNCH2CH2)3N]TiCl can be prepared
readily from Li3[(Et3SiNCH2CH2)3N] and TiCl4(THF)2
in pentane in a manner analogous to the synthesis of
[(Me3SiNCH2CH2)3N]TiCl. Li3[(Et3SiNCH2CH2)3N] had
to be prepared in situ from (Et3SiNHCH2CH2)3N, as it
could not be crystallized. Orange, crystalline [(Et3-
SiNCH2CH2)3N]TiCl, which was obtained in 30% yield
overall, had 1H and 13C NMR spectra consistent with
the expected trigonal bipyramidal, 3-fold symmetric
structure.
Addition of t-BuLi to [(Et3SiNCH2CH2)3N]TiCl in
pentane yielded a yellow-green reaction mixture, but
NMR spectra of aliquots revealed only resonances for
unreacted starting materials. However, when the reac-
tion mixture was stored at -35 °C for 1 to 10 days,
orange-red needles were deposited along with a white
precipitate of LiCl. Proton and carbon NMR spectra of
the orange-red crystalline product were consistent with
its formulation as [(Et3SiNCH2CH2)3N]Ti(t-Bu). The
tert-butyl proton resonance is found at 1.59 ppm while
the quaternary carbon resonance is found at 70.3 ppm
in the carbon NMR spectrum. [(Et3SiNCH2CH2)3N]Ti-
(t-Bu) is not likely to form via nucleophilic substitution
at Ti in view of severe steric constraints. A possible
explanation is that [(Et3SiNCH2CH2)3N]TiCl is slowly
reduced by t-BuLi to [(Et3SiNCH2CH2)3N]Ti (see below)
and LiCl and that [(Et3SiNCH2CH2)3N]Ti subsequently
traps a tert-butyl radical to give [(Et3SiNCH2CH2)3N]-
Ti(t-Bu). Yields for this reaction therefore are under-
standably low (15-30%) and appear to decrease upon
scaling up the reaction. In our hands the reaction is
reproducible only on a scale of ∼200 mg of [(Et3SiNCH2-
CH2)3N]TiCl.
Syn th esis of [(C6F 5NCH2CH2)3N]Ti Com p lexes. A
ligand that is potentially more resistent to metalation
reactions of the type observed for titanium silyl deriva-
tives is [(C6F5NCH2CH2)3N]3- 7
Since Li3[(C6F5NCH2-
.
CH2)3N] does not appear to be a stable isolable species,
the parent ligand was employed in the presence of a
base. Addition of a mixture of (C6F5NHCH2CH2)3N and
22
Et3N in THF to TiCl4(THF)2 in THF yielded the
chloride derivative shown in eq 2 in a >90% yield. The
[(Et3SiNCH2CH2)3N]Ti(t-Bu) decomposes slowly and
smoothly at 25 °C in C6D6 to give isobutylene and what
we propose to be [(Et3SiNCH2CH2)3N]TiH, according to
NMR studies. The hydride resonance in [(Et3SiNCH2-
CH2)3N]TiH appears at 8.21 ppm in C6D6. This chemi-
cal shift should be compared with the resonance at 8.29
ppm in [(Me3SiNCH2CH2)3N]TiH above and at 8.5 ppm
in Ta(O-2,6-i-Pr2C6H3)2(H)(PMe3).21 Loss of isobutylene
from [(Et3SiNCH2CH2)3N]Ti(t-Bu) follows first-order
kinetics in CDCl3 (k (40 °C) ) 1.2 × 10-4 s-1 and k (50
°C) ) 2.9 × 10-4 s-1, as determined by proton NMR);
under these conditions as soon as [(Et3SiNCH2CH2)3-
N]TiH is formed it is converted into [(Et3SiNCH2-
CH2)3N]TiCl, which is thermally stable in CDCl3 (28 h
bromo and iodo derivatives could be prepared in analo-
gous reactions involving TiX4 (X ) Br, I) in dichlo-
romethane. Highly insoluble, dark red [(C6F5NCH2-
CH2)3N]Ti(OTf) could be prepared by treating [(C6-
F5NCH2CH2)3N]TiCl with TMSOTf in DME. All [(C6F5-
NCH2CH2)3N]TiX species are highly colored crystalline
compounds (the iodo derivative is dark purple) with
proton NMR spectra consistent with their expected
3-fold symmetry on the NMR time scale, i.e., structures
analogous to that of [(C6F5NCH2CH2)3N]MoCl7 in which
the donor nitrogen atom is bound to the metal, as shown
in eq 2.
[(C6F5NCH2CH2)3N]TiMe could be prepared in ∼80%
yield as red-orange crystals by treating [(C6F5NCH2-
CH2)3N]TiI or [(C6F5NCH2CH2)3N]TiBr with MeMgCl.
Reactions involving LiCH3 or ZnMe2 in several different
solvents gave low to moderate yields. [(C6F5NCH2-
(19) Bercaw, J . E.; Marvich, R. H.; Bell, L. G.; Brintzinger, H. H. J .
Am. Chem. Soc. 1972, 94, 1219.
(20) Bennett, J . L.; Wolczanski, P. T. J . Am. Chem. Soc. 1994, 116,
2179.
(21) No¨th, H.; Schmidt, M. Organometallics 1995, 14, 4601.
(22) Manzer, L. E. Inorg. Synth. 1982, 21, 135.

1472 Organometallics, Vol. 15, No. 5, 1996
Schrock et al.
not yield complexes that we can say unambiguously are
analogous [(C6F5NCH2CH2)3N]TiR species. We suspect
that nucleophilic replacement of Cl, Br, or I is simply
too slow if the alkyl is larger than ethyl, and other
reaction pathways (attack on the C6F5 rings or reduction
via electron transfer) begin to dominate.
Reactions between [(C6F5NCH2CH2)3N]TiMe or [(C6F5-
NCH2CH2)3N]TiEt and hydrogen (1 atm) so far have
been inconclusive. It does not appear that hydrogenoly-
sis of the Ti-C bond is facile and that hypothetical
[(C6F5NCH2CH2)3N]TiH is accessible in this manner.
Syn th esis of [(Me3SiNCH2CH2CH2)3N]Ti Com -
p lexes. We felt that a potentially useful variation of a
trisubstituted TREN ligand would be a trisubstituted
tris(3-aminopropyl)amine (TRPN) ligand.23,24 A ligand
that contains one more methylene unit per backbone
arm might allow transition metals (especially larger
second- or third-row metals, actinides, or early lan-
thanides) to reside deeper inside the steric “pocket”,
quite possibly in the plane defined by the three equato-
rial nitrogens. A potential disadvantage is that the
apical nitrogen donor might be more prone to dissocia-
tion than in analogous TREN derivatives.
Deprotonation of TRPN with 3.3 equiv of BuLi in THF
at -70 °C followed by quenching with 3.3 equiv of
TMSCl gave (Me3SiNHCH2CH2CH2)3N, which was depro-
tonated once more with 3.3 equiv of BuLi in pentane at
-70 °C to give microcrystalline Li3[(Me3SiNCH2CH2-
CH2)3N]. Addition of Li3[(Me3SiNCH2CH2CH2)3N] to
F igu r e 1. (a) TiMe resonance in the proton- and fluorine-
coupled 13C NMR NMR spectrum of [(C6F5NCH2CH2)3N]-
TiMe. (b) TiMe resonance in the proton-coupled, fluorine-
decoupled 13C NMR NMR spectrum of [(C6F5NCH2C-
H2)3N]TiMe.
22
TiCl4(THF)2 in pentane at -35 °C gave amber [(Me3-
SiNCH2CH2CH2)3N]TiCl in high yield (eq 3). Isolated
CH2)3N]TiCl reacted relatively slowly with CH3MgCl to
give a mixture of ∼85% [(C6F5NCH2CH2)3N]TiMe and
∼15% [(C6F5NCH2CH2)3N]TiCl (by proton NMR). Use
of excess CH3MgCl led to more complex mixtures from
which [(C6F5NCH2CH2)3N]TiMe could not be isolated
readily. The proton and fluorine NMR spectra of [(C6F5-
NCH2CH2)3N]TiMe are characteristic of complexes of
this general type, with one exception. The methyl
resonance in the proton NMR spectrum is relatively
broad and shows fine structure consistent with it being
a septet (J ≈ 1.5 Hz). The proton-decoupled carbon
NMR spectrum showed a methyl resonance at 72.26
ppm which was split into a septet (J CF ≈ 1.9 Hz). The
proton and fluorine coupled carbon NMR spectrum
shows a methyl quartet (1J CH ) 118 Hz) with additional
coupling to six nuclei of spin 1/2 (J ≈ 2 Hz; Figure 1a).
When the methyl carbon is decoupled from fluorine each
of the quartet lines narrows as shown in Figure 1b.
Therefore, we conclude that the methyl group’s protons
and carbon are coupled to six fluorines in the three C6F5
groups in [(C6F5NCH2CH2)3N]TiMe, presumably the six
ortho fluorines. Coupling of the ortho fluorines to the
methyl protons was not observable by 19F NMR.
[(C6F5NCH2CH2)3N]TiEt could be prepared by treat-
ing [(C6F5NCH2CH2)3N]TiBr with MgEt2(dioxane). Ad-
dition of EtMgCl to [(C6F5NCH2CH2)3N]TiBr or [(C6F5-
NCH2CH2)3N]TiI resulted in halogen exchange to give
a mixture containing [(C6F5NCH2CH2)3N]TiCl rather
than pure [(C6F5NCH2CH2)3N]TiEt. Evidently halogen
exchange is faster relative to displacement of halogen
by the alkyl group for steric reasons in reactions
involving EtMgCl but not in reactions involving MeMgCl.
Attempts to synthesize n-Bu, i-Bu, s-Bu, and neopen-
tyl complexes using a variety of alkylating agents did
yields were limited to ∼50% as a consequence of the
high solubility of [(Me3SiNCH2CH2CH2)3N]TiCl in hy-
drocarbon solvents. The room-temperature proton NMR
spectrum of [(Me3SiNCH2CH2CH2)3N]TiCl in C6D6 shows
the expected TMS resonance at 0.52 ppm but six
complex methylene resonances in the 1.25-4.30 ppm
range. Heating a sample of [(Me3SiNCH2CH2CH2)3N]-
TiCl in toluene-d8 to 90 °C did not induce any change
in line shapes. Carbon NMR spectra confirmed the
presence of three unique methylene carbons, each of
which has two diastereotopic protons bonded to it.
These data suggest that the ligand framework is “rigid”
on the NMR time scale in [(Me3SiNCH2CH2CH2)3N]-
TiCl, i.e., that methylene protons on a given carbon
atom cannot interconvert readily by “flipping” of the six-
membered TiN2C3 ring.
The structure of [(Me3SiNCH2CH2CH2)3N]TiCl was
determined by X-ray crystallography (Table 1). Two
views of the structure are shown in Figure 2, while
selected distances and angles are shown in Table 2. The
Ti atom is nearly coplanar with the equatorial nitrogens
(average Ti-Neq ) 1.90 Å), and the Ti-Nax distance
(Ti-Nax ) 2.360(6) Å) is somewhat longer compared to
the V-Nax bond distance in [(Me3SiNCH2CH2)3N]VCl
(23) vanWinkle, J . L.; McClure, J . D.; Williams, P. H. J . Org. Chem.
1966, 31, 3300.
(24) Chin, J .; Banaszczyk, M.; J ubian, V.; Zou, X. J . Am. Chem. Soc.
1989, 111, 186.

Ti Complexes Containing Triamido-Amine Ligands
Organometallics, Vol. 15, No. 5, 1996 1473
Ta ble 1. Exp er im en ta l Deta ils for th e X-r a y
Str u ctu r e of [(Me3SiNCH2CH2CH2)3N]TiCl
A. Crystal Data
empirical formula
fw
C18H45N4Si3TiCl
485.19
cryst color, habit
cryst dimens
cryst system
orange, prismatic
0.280 × 0.320 × 0.180 mm
monoclinic
no. reflcns used for unit
tot. 7971; unique 7685
(Rint ) 0.050)
cell determination (2θ range) 25 (13.0-22.0°)
ω scan peak width
at half-height
0.27
lattice params
a ) 17.900(2) Å
b ) 17.134(2) Å
c ) 20.116(3) Å
â ) 113.60(2)°
V ) 5653(3) Å
P21/n (No. 14)
8
space group
Z value
Dcalc
F000
µ(Mo KR)
1.140 g/cm3
2096
5.30 cm-1
B. Intensity Measurements
diffractometer
radiation
temp
Enraf-Nonius CAD-4
Mo KR (λ ) 0.710 69 Å)
25 ( 1 °C
attenuator
Zr foil (factor ) 17.9)
2.8°
take-off angle
detector aperture
cryst to detector dist
scan type
scan rate
scan width
2.0 × 2.5 × 2.0 mm
21 cm
ω-2θ
(1.9-16.5°)/min (in ω)
(0.80 + 0.35 tan θ)°
44.9°
2θmax
no. of reflcns measd
F igu r e 2. Two Chem 3D views of the structure of [(Me3-
SiNCH2CH2CH2)3N]TiCl.
tot. 7971
unique: 7685 (Rint ) 0.050)
Lorentz-polarization
abs (transm factors: 0.74-1.11)
secondary extinction
corrs
Ta ble 2. Selected In tr a m olecu la r Dista n ces (Å)
a n d An gles (d eg) for th e Non -Hyd r ogen Atom s of
[(Me3SiNCH2CH2CH2)3N]TiCl
(coeff: 0.53392 × 10-7
)
Bond Lengths
C. Structure Solution and Refinement
Ti(2)-N(2)
Ti(2)-N(4)
Ti(2)-N(6)
1.910 (5)
1.905 (6)
1.897 (5)
Ti(2)-Cl(2)
2.352 (2)
2.360 (6)
struct solution
refinement
direct methods
Ti(2)-N(8)
full-matrix least-squares
function minimized
least-squares weights
p-factor
anomalous dispersion
no. observns (I > 3.00σ(I))
no. variables
reflcns/param ratio
residuals: R; Rw
goodness of fit indicator
max shift/error in final cycle
max peak in final diff map
min peak in final diff map
∑w(|Fo| - |Fc|)2
4Fo2/s2(Fo
)
2
Bond Angles
0.03
all non-H atoms
3619
488
7.42
Ti(2)-N(2)-Si(2) 129.7 (3) N(2)-Ti(2)-N(6)
Ti(2)-N(4)-Si(4) 130.0 (3) N(4)-Ti(2)-N(6)
Ti(2)-N(6)-Si(6) 129.7 (4) N(8)-Ti(2)-N(2)-Si(2) 136.8 (4)
N(8)-Ti(2)-Cl(2) 179.0 (2) N(8)-Ti(2)-N(4)-Si(4) 142.4 (4)
N(2)-Ti(2)-N(4) 120.6 (4) N(8)-Ti(2)-N(6)-Si(6) 137.5 (4)
117.2 (2)
119.6 (4)
0.052; 0.051
1.40
0.03
[(Me3SiNCH2CH2)3N]VdNH (average 177°), and [(Me3-
SiNCH2CH2)3N]VCl (average 147°).13 One could specu-
late that the silyl groups are “tilted” to a greater degree
in [(Me3SiNCH2CH2CH2)3N]TiCl as a consequence of the
chair form of each TiN2C3 ring. The Ti-Neq-Si angle
in [(Me3SiNCH2CH2CH2)3N]TiCl (120°) is slightly less
than what it is the vanadium complexes noted above
(ca. 126°).
0.22 e/Å3
-0.23 e/Å3
(V-Nax ) 2.238 Å).2 The Ti atom is displaced from the
equatorial NNN plane by 0.203 Å in [(Me3SiNCH2CH2-
CH2)3N]TiCl compared to 0.310 Å in [(Me3SiNCH2-
CH2)3N]VCl. The Ti-Cl bond distance (2.353(2) Å) is
also longer than that reported in [(Me3SiNCH2CH2)3N]-
TiCl (2.259(6) Å).25 An important structural feature
that must be a consequence of the longer “arms” in
[(Me3SiNCH2CH2CH2)3N]TiCl is the formation of three
“chair form” TiN2C3 rings. The resulting “propeller”
orientation of the trimethylsilyl groups can be measured
by the dihedral angle Nax-Ti-Neq-Si. In [(Me3SiNCH2-
CH2CH2)3N]TiCl the average dihedral angle is 138°.
This value should be compared to analogous dihedral
angles in [(Me2(t-Bu)SiNCH2CH2)3N]V (average 168°),
[(Me3SiNCH2CH2CH2)3N]TiCl is alkylated cleanly by
1.1 equiv of LiMe in cold ether to furnish the expected
methyl complex (eq 4). Its high solubility limited
isolated yields, however. Proton and carbon NMR
spectra of the methyl complex show broad ligand
backbone (methylene) resonances consistent with a
(25) Airoldi, C.; Bradley, D. C.; Chudzynska, H.; Hursthouse, M. B.;
Malik, K. M. A.; Raithby, P. R. J . Chem. Soc., Dalton Trans. 1980,
2010.

1474 Organometallics, Vol. 15, No. 5, 1996
Schrock et al.
[(Me3SiNCH2CH2)3N]Ti(s-Bu ). A 20 mL vial containing
[(Me3SiNCH2CH2)3N]TiCl (0.846 g, 1.91 mmol) in 15 mL of
pentane was treated with a 1.3 M solution of s-BuLi in
cyclohexane (1.1 equiv, 800 µL) at -35 °C. An immediate color
change to green was observed, but after 2-3 min a white LiCl
precipitate was observed and the color of the reaction mixture
had become yellow-orange. After being warmed to 25 °C and
stirred for 1.5 h, the reaction mixture was filtered through a
plug of alumina (height, 2 cm; diameter, 2 cm). The yellow-
orange filtrate was concentrated in vacuo to give orange
crystalline solid (657 mg, 1.42 mmol, 75%). A pentane solution
of this material was chilled to -35 °C for 3 days to provide
[(Me3SiNCH2CH2)3N]Ti(s-Bu) (397 mg, 45%) as an orange
crystalline solid that was pure by proton NMR except for a
trace of [(Me3SiNCH2CH2)3N]Ti(n-Bu): 1H NMR (C6D6) δ 3.40
(ddd, 3, NCH2), 3.31 (ddd, 3, NCH2), 2.65 (ddq, 1, CH2), 2.17
(t, 6, NCH2), 1.77 (ddq, 1, CH2), 1.75 (d, CH3), 1.06 (t, CH3),
0.85 (ddq, TiCH), 0.33(s, SiMe3); 13C NMR (C6D6) δ 82.88 (d,
TiCH), 62.51 (t, NCH2), 50.52 (t, NCH2), 32.91 (t, CH2), 22.22
more rapid “flipping” of the TiN2C3 rings and consequent
equilibration of the diastereotopic methylene protons,
in contrast to the behavior observed in the chloride
derivative. We speculate that the more electron-rich
metal center in the methyl derivative allows more facile
dissociation of the axial amine donor nitrogen, a process
that should facilitate equilibration of methylene protons
on a given backbone carbon atom.
Con clu sion s
We have shown that titanium halide and some alkyl
complexes can be prepared that contain the triamido-
amine ligand [(Et3SiNCH2CH2)3N]3-, [(C6F5NCH2CH2)3-
N]3-, or [(Me3SiNCH2CH2CH2)3N]3-. However, so far
such ligands have not proven to have any significant
advantages as far as stabilization of a Ti(IV) monohy-
dride complex is concerned. TRPN derivatives, of which
the last is an example, might prove useful in chemistry
of larger second- or third-row metals, actinides, or early
lanthanides, especially if substituents larger than TMS
(e.g., Et3Si or i-Pr3Si) are employed.
(q, CH3), 15.03 (q, CH3), 1.97 (q, SiMe3). Anal. Calcd for C19
-
H48N4Si3Ti: C, 49.10; H, 10.41; N, 12.05. Found: C, 48.69;
H, 10.14; N, 12.06.
Ti[(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH2]. A 50 mL
pressure vessel containing [(Me3SiNCH2CH2)3N]Ti(s-Bu) (0.771
g, 1.67 mmol) in 12 mL of benzene was freeze-pump-thaw
degassed three times prior to admission of H2 (1 atm), with
the vessel at -196 °C. The reaction mixture was warmed to
25 °C with the vessel closed, giving approximately 3 atm of
H2. The orange-red solution turned yellow over a 48 h period.
Removal of the benzene in vacuo gave a yellow-brown oil (667
mg, 1.64 mmol, 98%). The oil was transferred to a sublimation
vessel. Sublimation (50-60 °C, 0.05 Torr, probe temperature
) -78 °C) provided Ti(Me3SiNCH2CH2)2NCH2CH2NSi(CH2)-
Me2 (571 mg, 1.40 mmol, 84%) as a waxy yellow solid: 1H NMR
(C6D6) δ 3.72 (t, NCH2), 3.23 (ddd, 2, NCH2), 3.12 (ddd, 2,
NCH2), 2.34 (t, NCH2), 2.27 (dd, 2, NCH2), 2.25 (dd, 2, NCH2),
1.31 (s, TiCH2Si), 0.37 (s, SiMe2), 0.32 (s, SiMe3); 13C NMR
(C6D6) δ 58.47 (t, NCH2), 56.91 (t, NCH2), 55.87 (t, TiCH2Si),
53.66 (t, NCH2), 48.84 (t, NCH2), 1.87 (q, SiMe2), 1.48 (q,
SiMe3).
Exp er im en ta l Section
Gen er a l Meth od s. All experiments were carried out in
purified, dry solvents under a nitrogen atmosphere in a
Vacuum Atmospheres drybox or using standard Schlenk
techniques, unless otherwise specified. TiBr4, TiI4, and N(CH2-
CH2CH2NH2)3 were purchased from Strem Chemicals and used
as received. TiCl4(THF)2,22 Li3(Me3SiNCH2CH2)3N,13,26,27 and
(C6F5NHCH2CH2)3N7 were prepared by literature methods.
NMR coupling constants normally are not noted unless they
are unusual or informative. Within the TREN backbond J HH
) 5-6 Hz and J CH ≈ 135 Hz for the methylene groups.
P r ep a r a tion of Com p ou n d s. [(Me3SiNCH 2CH2)3N]-
TiCl. A 100 mL round bottom flask was charged with
TiCl4(THF)2 (2.64 g, 7.91 mmol) and Li3(Me3SiNCH2CH2)3N
(3.01 g, 7.91 mmol). Pentane (60 mL) was added, and the
mixture was stirred for 26 h at 25 °C. The off-white LiCl
precipitate was removed by filtration through a bed of Celite,
and the deep orange filtrate was concentrated in vacuo. The
crude yield of orange crystalline solid was 3.02 g (6.82 mmol,
86%). A solution of the crude material in a minimum of
pentane was chilled to -35 °C to provide pure [(Me3SiNCH2-
CH2)3N]TiCl as orange crystals (1.99 g, 4.49 mmol, 57%): 1H
(Et3SiNHCH2CH2)3N. This ligand was prepared from
TREN and Et3SiCl in a manner analogous to that used to
prepare (Me3SiNHCH2CH2)3N.13 It was isolated without
purification and treated with 3 equiv of Li-n-butyl in order
to form Li3(Me3SiNCH2CH2)3N in situ.
[(Et3SiNCH2CH2)3N]TiCl. TiCl4(THF)2 (14.29 g, 42.80
mmol) was added to 250 mL of pentane at -35 °C, and then
a solution of crude Li3[(Et3SiNCH2CH2)3N] (42.80 mmol, 0.25
M in pentane) was added. The reaction mixture was allowed
to warm to 25 °C and was stirred for 24 h and then was filtered
through a bed of Celite. The pentane was removed in vacuo
to give an oily residue which was dissolved in 50 mL of
pentane. The pentane solution was chilled to -35 °C for 72
h. Orange crystals were collected by filtration, washed quickly
with 10 mL of cold pentane, and dried in vacuo (7.33 g, 12.90
mmol, 30%): 1H NMR (C6D6) δ 3.48 (t, NCH2), 2.41 (t, NCH2),
1.10 (t, CH3), 0.94 (q, SiCH2); 13C NMR (C6D6) δ 63.48 (NCH2),
NMR (C6D6) δ 3.36 (t, CH2), 2.276 (t, CH2), 0.35 (s, SiMe3); 13
C
NMR (C6D6) δ 63.17 (CH2), 50.81 (CH2), 1.61 (SiMe3). Anal.
Calcd for C15H39ClN4Si3Ti: C, 40.66; H, 8.87; N, 12.64; Cl, 8.00.
Found: C, 40.36; H, 8.64; N, 12.53; Cl, 8.05.
[(Me3SiNCH2CH2)3N]Ti(n -Bu ). A 20 mL vial containing
[(Me3SiNCH2CH2)3N]TiCl (0.81 g, 1.82 mmol) in 12 mL of
pentane was treated with a 1.6 M solution of n-BuLi in
hexanes (1.1 equiv, 800 µL) at -35 °C. After the mixture was
warmed to 25 °C and stirred for 2 h, it was filtered through a
plug of alumina (height, 2 cm; diameter, 2 cm). The yellow-
gold filtrate was concentrated in vacuo to give a yellow
crystalline solid (581 mg, 1.26 mmol, 69%). A pentane solution
of this material was chilled to -35 °C to provide [(Me3SiNCH2-
CH2)3N]Ti(n-Bu) (480 mg, 57%) as lemon yellow crystals: 1H
NMR (C6D6) δ 3.35 (t, NCH2), 2.15 (t, NCH2), 2.15 (m, CH2),
1.48 (m, CH2), 1.39 (m, CH2), 1.03 (t, CH3), 0.33 (s, SiMe3);
13C{1H} NMR (C6D6) δ 72.90 (TiCH2), 61.99 (NCH2), 50.39
(NCH2), 35.32 (CH2), 29.40 (CH2), 13.90 (CH2), 1.68 (SiMe3).
Anal. Calcd for C19H48N4Si3Ti: C, 49.10; H, 10.41; N, 12.05.
Found: C, 48.92; H, 10.10; N, 12.40.
51.45 (NCH2), 8.01 (SiEt3), 6.18 (SiEt3). Anal. Calcd for C24
57ClN4Si3Ti: C, 50.63; H, 10.09; N, 9.84. Found: C, 50.72;
H, 10.36; N, 9.45.
-
H
[(Et3SiNCH2CH2)3N]Ti(t-Bu ). A solution of [(Et3SiNCH2-
CH2)3N]TiCl (276 mg, 490 µmol) in pentane (40 mL) was
chilled to -35 °C and treated with t-BuLi (530 µmol, 315 µL,
1.7 M in pentane). After the mixture was stirred for 25 min
at 25 °C, the volume was reduced to 5 mL under reduced
pressure, and the turbid green reaction mixture was chilled
to -35 °C. After 48 h a crop (ca. 50 mg) of large orange crystals
had formed mixed with LiCl. The LiCl was slurried in the
cold supernatant and removed via pipet: 1H NMR (C6D6) δ
3.53 (br, NCH2), 2.26 (br, NCH2), 1.59 (s, CMe3), 1.14 (t,
(26) Duan, Z.; Yound, V. G.; Verkade, J . G. Inorg. Chem. 1995, 34,
2179.
(27) Gudat, D.; Verkade, J . G. Organometallics 1989, 8, 2772.

Ti Complexes Containing Triamido-Amine Ligands
Organometallics, Vol. 15, No. 5, 1996 1475
SiCH2CH3), 0.97 (q, SiCH2); 13C NMR (C6D6) δ 70.27 (TiCMe3),
63.73 (NCH2), 51.80 (NCH2), 35.73 (TiCMe3), 8.48 (SiEt3), 7.18
(SiEt3).
Calcd for TiC24H12N4F15I: C, 35.32; H, 1.48; N, 6.86; I, 15.55.
Found: C, 35.28; H, 1.44; N, 7.02; I, 15.72.
[(C6F 5NCH2CH2)3N]Ti(OTf). A solution of [(C6F5NCH2-
CH2)3N]TiCl (1.00 g, 1.38 mmol) in 70 mL of dimethoxyethane
was added to a precooled (-30 °C) solution containing trimeth-
ylsilyl triflate (350 µL, 1.38 mmol). The reaction mixture was
stirred at room temperature overnight, and the insoluble red
product was collected on a glass frit and washed with dimethox-
yethane and pentane (990 mg, 1.18 mmol, 86%). The product
[(Et3SiNCH2CH2)3N]Ti(OTf). A solution of [(Et3Si)3N4]-
TiCl (1.02 g, 1.78 mmol) in pentane (30 mL) was treated with
fresh sodium amalgam (2.67 mmol Na, 62 mg Na, 12.24 g Hg),
and the reaction mixture was stirred vigorously for 48 h. The
solids were allowed to settle, and the bright blue solution was
decanted and filtered through a bed of Celite. The pentane
was removed from the filtrate in vacuo to give a viscous blue
liquid. This liquid was dissolved in ether (40 mL), and the
solution was chilled to -35 °C. [FeCp2][O3SCF3] (1.78 mmol,
598 mg) was added to the stirred solution in solid portions
over a period of 1 to 2 min to produce a golden reaction
mixture. After 40 min at 25 °C the solution was filtered and
the ether was removed in vacuo. Ferrocene was removed by
sublimation (45 °C, 0.05 Torr, probe temperature -78 °C) over
3 to 4 h and the residue was recrystallized from pentane (45
mL) to provide yellow-orange crystals (966 mg, 1.41 mmol,
79%): 1H NMR (C6D6) δ 3.47 (t, NCH2), 2.40 (t, NCH2), 1.07
(t, CH3), 0.88 (q, SiCH2); 13C NMR (C6D6) δ 65.51 (NCH2), 51.59
(NCH2), 7.96 (SiEt3), 5.68 (SiEt3); 19F NMR (C6D6) δ -75 (CF3).
Anal. Calcd for C25H57N4Si3O3SF3Ti: C, 43.97; H, 8.41; N,
8.20. Found: C, 44.20; H, 8.71; N, 7.80.
is too insoluble to obtain NMR spectra. Anal. Calcd for C25
12N4F18SO3Ti: C, 35.82; H, 1.44; N, 6.68. Found: C, 36.03;
H, 1.62; N, 6.45.
-
H
[(C6F 5NCH2CH2)3N]Ti(CH3). MeMgCl (3.0M in THF, 314
µL, 1.22 equiv) was added dropwise over 10 min to a -40 °C
methylene chloride solution of [(C6F5NCH2CH2)3N]TiI (628 mg,
0.769 mmol). The reaction appeared to be virtually instanta-
neous, but the reaction mixture was allowed to stir for 4 h at
room temperature before placing it in the -40 °C freezer. After
16 h the orange-red crystalline product was filtered off (435
mg, 0.62 mmol, 80%): 1H NMR (CD2Cl2) δ 3.92 (t, 6, CH2),
1
3.07 (t, 6, CH2), 0.43 (m, 3, CH3); H NMR (C6D6) δ 3.32 (t, 6,
CH2), 2.27 (t, 6, CH2); 19F NMR δ -150.10 (d, 6, J FF ) 21),
-163.27 (t, 3, J FF ) 22) -164.47 (t, 6, J FF ) 22); 13C{1H} (CD2-
Cl2) δ 142.7-130.7 (C6F5), 72.3 (q, CH3, J CH ) 118, J CF ) 2),
57.28-53.37 (NCH2CH2N). Anal. Calcd for TiC25H15N4F15: C,
42.63; H, 1.72; N, 7.99. Found: C, 42.39; H, 2.03; N 8.18.
Alternatively CH3MgCl (0.780 mmol, 1.2 equiv) in ether was
slowly added to [(C6F5NCH2CH2)3N]TiBr (0.500 g, 0.650 mmol)
dissolved in toluene. The solution turned from dark red to a
bright orange, and salt precipitated from solution. The reac-
tion mixture was stirred for 1 h and filtered. The filtrate was
reduced to dryness in vacuo, and the residue was recrystallized
from dichloromethane at -40 °C.
[(C6F 5NCH 2CH 2)3N]TiCl. A solution of (C6F5NHCH2-
CH2)3N (3.86 g, 5.99 mmol) and triethylamine (1.88 g, 3.1
equiv) in THF (-35 °C) was added dropwise to a solution of
TiCl4(THF)2 (2.0 g, 5.99 mmol) in THF at -35 °C. The reaction
mixture was allowed to warm to room temperature and stirred
for 6 h. The red reaction mixture was then filtered through
Celite. The filtrate was taken to dryness in vacuo, and the
residue was dissolved in minimal methylene chloride. Chilling
the solution to -40 °C produced red microcrystals (2.60 g, 3.59
mmol, 60%): 1H NMR (C6D6) δ 3.30 (t, 6), 2.33 (t, 6); 19F NMR
δ -149.46 (d, 6, J FF ) 20), -149.46 (d, 6, J FF ) 20), -164.52
(t, 6, J FF ) 21). Anal. Calcd for TiC24H12N4F15Cl: C, 39.78;
H, 1.67; N, 7.73; Cl, 4.89. Found: C, 39.81; H, 1.97; N, 7.49;
Cl, 5.40.
[(C6F5NCH2CH2)3N]Ti(CH2CH3). [(C6F5NCH2CH2)3N]TiBr
(0.500 g, 0.650 mmol) was dissolved in toluene, and Mg(CH2-
CH3)2(dioxane) (0.066 g, 0.390 mmol, 1.2 equiv) in ether was
added slowly. The solution turned from dark red to a lighter
orange-red and then darkened again. After 2 h, the solution
was filtered and the filtrate was taken to dryness in vacuo.
The residue was recrystallized from a mixture of toluene and
pentane at -40 °C: 1H NMR (C6D6) δ 3.31 (t, 6, CH2), 2.08 (t,
6, CH2), 1.19 (q, 2, CH2CH3), 0.32 (t, 3, CH2CH3); 19F NMR δ
-149.74 (d, 6, J FF ) 19), -163.37 (t, 3, J FF ) 22), -164.35 (t,
6, J FF ) 21). Anal. Calcd for TiC26H17N4F15: C, 43.48; H, 2.39;
N, 7.80. Found: C, 43.06; H, 2.60; N, 7.52.
Li3[(Me3SiNCH2CH2CH2)3N]. A 1 L Schlenk flask was
charged with N(CH2CH2CH2NH2) (18.00 g, 0.096 mol) in 350
mL of THF. The solution was stirred magnetically and cooled
to -65 °C. Butyllithium (0.296 mol, 2.5 M in hexane) was
syringed in; a white precipitate formed immediately. The
mixture was allowed to warm to room temperature over 7 h,
cooled again to -65 °C, and treated with TMSCl (32.16 g, 0.296
mol). The white mixture was allowed to warm to room
temperature overnight. Solvents were removed in vacuo, and
the residue was extracted three times with 150 mL of pentane
and filtered through a bed of Celite. The solvents were
removed from an aliquot of the filtrate to give a pale yellow
oil: 1H NMR (CDCl3) δ 2.68 (q, 6, NCH2CH2CH2), 2.37 (t, 6,
NCH2CH2CH2), 1.49 (m, 6, NCH2CH2CH2), 0.01 (s, 27, SiMe3).
The pentane extracts were combined, cooled to -65 °C, and
treated with butyllithium (0.30 mmol, 2.5M in hexane). The
mixture containing a thick white precipitate was allowed to
warm to room temperature overnight and then was chilled to
-35 °C overnight. The white microcrystalline powder was
filtered off, washed quickly with cold pentane, and dried in
vacuo to give pure product (30.52 g, 72.2 mmol, 75%).
[(C6F 5NCH2CH2)3N]TiBr . TiBr4 (1.00 g, 2.72 mmol) was
dissolved in dichloromethane, and the solution was cooled to
-40 °C. A solution containing (C6F5NHCH2CH2)3N (1.75 g,
2.72 mmol) and NEt3 (0.866 g, 8.54 mmol, 3.04 equiv) in CH2-
Cl2 was also cooled to -40 °C and then added slowly over a
period of several minutes to the TiBr4. The reaction mixture
darkened from light orange-yellow to deep red. After the
mixture was stirred for 3 h, it was reduced to dryness in vacuo
and the residue was dissolved in toluene. The extract was
filtered, and the toluene was removed from the filtrate in
vacuo. The product was recrystallized from a minimum of
dichloromethane at -35 °C to give nearly black crystals (1.64
g, 2.13 mmol, 78%): 1H NMR (C6D6) δ 3.31 (t, 6, CH2), 2.32 (t,
6, CH2); 19F NMR δ -148.95 (d, 6, J FF ) 19), -160.81 (t, 3,
J FF ) 22), -164.35 (t, 6, J FF ) 20). Anal. Calcd for TiC24H12
-
N4F15Br: C, 37.48; H 1.57; N, 7.28. Found: C, 37.55; H, 1.63;
N 7.10.
[(C6F5NCH2CH2)3N]TiI. A solution containing (C6F5NHCH2-
CH2)3N (1.16 g, 1.82 mmol) and triethylamine (570 mg, 3.1
equiv) in methylene chloride (-35 °C) was added dropwise to
a solution of TiI4 (1.0 g, 1.80 mmol) in methylene chloride at
-35 °C. The reaction mixture was allowed to warm to room
temperature and was stirred for more than 3 h. The dark
purple reaction mixture was filtered through Celite to remove
the ammonium salts. The filtrate was taken to dryness in
vacuo, and the residue was extracted with 1,2-dimethoxy-
methane (dme). The solution was filtered through Celite, and
the solvent was removed from the filtrate in vacuo. The
residue was dissolved in a small amount of dichloromethane
and the solution was chilled to -35 °C to give dark purple
microcrystals (1.175 g, 1.44 mmol, 80%): 1H NMR (C6D6) δ
3.32 (t, 6, CH2), 2.27 (t, 6, CH2); 19F NMR δ -148.32 (d, 6, J FF
) 19), -160.50 (t, 3, J FF ) 22), -164.16 (t, 6, J FF ) 20). Anal.
[(Me3SiNCH 2CH 2CH 2)3N]TiCl. Li3[(Me3SiNCH2CH2C-
H2)3N] (2.30 g, 5.44 mmol) was added in one portion to a stirred
suspension of TiCl4(THF)2 (2.00 g, 5.99 mmol) in 50 mL of
pentane at -35 °C. The canary yellow mixture darkened
slightly and was allowed to stir at room temperature overnight.
LiCl and excess TiCl4(THF)2 were removed via filtration

1476 Organometallics, Vol. 15, No. 5, 1996
Schrock et al.
Of the 7971 reflections collected, 7685 were unique (Rint
through Celite. The yellow filtrate was concentrated and
chilled to -35 °C to give amber plates of [(Me3SiNCH2CH2-
CH2)3N]TiCl (1.19 g, 2.45 mmol, 45%): 1H NMR (C6D6) δ 4.24
(td, 3), 3.36 (td, 3), 3.24 (m, 3), 1.64 (m, 6), 1.25 (m, 3), 0.52 (s,
27, SiMe3); 13C{H} NMR (C6D6) δ 59.24, 51.18, 27.66, 1.38.
Anal. Calcd for C18H45N4ClSi3Ti: C, 44.56; H, 9.35; N, 11.55.
Found: C, 44.44; H, 9.21; N, 11.38.
[(Me3SiNCH 2CH 2CH 2)3N]TiCH 3. Methyllithium (0.79
mmol, 1.4 M in ether) was added dropwise to a stirred solution
of [(Me3SiNCH2CH2CH2)3N]TiCl (350 mg, 0.72 mmol) in 25 mL
of ether at -35 °C. The yellow mixture was stirred overnight,
and ether was removed in vacuo. The yellow residue was
taken up in pentane, and the solution was filtered through a
bed of Celite. The filtrate was concentrated in vacuo and
chilled to -35 °C to give yellow crystals of the product (67 mg,
20%): 1H NMR (C6D6) δ 4.26 (m, 3), 3.20 (m, 6), 1.60 (m, 6),
1.18 (m, 3), 0.89 (s, 3, TiCH3), 0.35 (s, 27, SiMe3); 13C{H} NMR
(C6D6) δ 58.01, 50.12, 44.18, 28.72 (TiCH3), 1.44. Anal. Calcd
for C19H48N4Si3Ti: C, 49.10; H, 10.41; N, 12.05. Found: C,
49.23; H, 10.02; N, 11.94.
)
0.050); equivalent reflections were merged. The structure was
solved by direct methods. Non-hydrogen atoms were refined
anisotropically. The final cycle of full-matrix least-squares
refinement was based on 3619 observed reflections (I > 3.00σ-
(I)) and 488 variable parameters and converged (largest
parameter shift was 0.03 times its esd) with unweighted and
weighted agreement factors of R ) 0.052 and Rw ) 0.051. See
the Supporting Information and Table 2 for further details.
Ack n ow led gm en t. R.R.S. thanks the National Sci-
ence Foundation (Grant CHE 91 22827) for research
support. S.L. thanks the MIT Undergraduate Research
Opportunities Program (UROP) for funding, A. LaPointe
for experimental advice, and K. Totland for NMR
spectra. T.W. thanks the MIT Undergraduate Research
Opportunities Program (UROP) for funding and M. K.
for experimental advice. M. K. thanks the Rothschild
Foundation for a postdoctoral fellowship.
X-r a y Str u ctu r e of [(Me3SiNCH2CH2CH2)3N]TiCl. An
orange prismatic crystal of C18H45N4Si3TiCl was mounted on
a glass fiber. All measurements were made on an Enraf-
Nonius CAD-4 diffractometer with graphite-monochromated
Mo KR radiation. Cell constants and an orientation matrix
for data collection, were obtained from a least-squares refine-
ment using the setting angles of 25 carefully centered reflec-
tions in the range 13.00 < 2θ < 22.00°.
Su p p or tin g In for m a tion Ava ila ble: Text describing
experimental details of the X-ray study of [(Me3SiNCH2CH2-
CH2)3N]TiCl, an ORTEP drawing of the structure, and tables
of final positional parameters, final thermal parameters, and
data collection parameters (13 pages). Ordering information
is given on any current masthead page.
OM9508389