Reaction of 1,3,5-triazacyclohexanes with TiCl4: Formation of cationic complexes

Article abstract of DOI:10.1002/ejic.200500122

N-substituted 1,3,5-triazacyclohexanes [R₃TAC; R = cyclohexyl, p-fluorobenzyl or Ph(CH₂)_n (n = 1, 2, 3)] react with excess TiCl₄ to give the corresponding cationic κ³ complexes [(R₃TAC)TiCl₃][Ti₂Cl₉]. Attempts to prepare complexes with titanium-free anions at lower Ti:R ₃TAC ratio or with added Me₃SiOTf lead to the same cations with [Ti₂Cl₁₀]^2- and [Ti₂Cl ₈(OTf)]^- anions. Five complexes as well as (p-fluorobenzyl)₃TAC have been characterised by X-ray crystallography. The ring C-H bonds engage in hydrogen bonding interactions in the crystals and strongly solvent and anion dependent ¹H NMR signals are detected in solution. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200500122

FULL PAPER
Reaction of 1,3,5-Triazacyclohexanes with TiCl4: Formation of Cationic
Complexes
Randolf D. Köhn,*[a] Philip Kampe,[a,b] and Gabriele Kociok-Köhn[a]
Dedicated to Professor Herbert Schumann on the occasion of his 70th birthday
Keywords: N ligands / Tridentate ligands / Titanium
N-substituted 1,3,5-triazacyclohexanes [R3TAC; R = cyclo-
hexyl, p-fluorobenzyl or Ph(CH2)n (n = 1, 2, 3)] react with
excess TiCl4 to give the corresponding cationic κ3 complexes
[(R3TAC)TiCl3][Ti2Cl9]. Attempts to prepare complexes with
robenzyl)3TAC have been characterised by X-ray crystal-
lography. The ring C–H bonds engage in hydrogen bonding
interactions in the crystals and strongly solvent and anion
1
dependent H NMR signals are detected in solution.
titanium-free anions at lower Ti:R3TAC ratio or with added
2–
Me3SiOTf lead to the same cations with [Ti2Cl10
]
and
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
[Ti2Cl8(OTf)]– anions. Five complexes as well as (p-fluo-
clohexane complexes of titanium are the neutral imido
complexes A shown in Scheme 1.[3,7,8] In this paper we de-
scribe the synthesis of cationic 1,3,5-triazacyclohexane
complexes by the reaction of the ligand with TiCl4
(Scheme 2).
Introduction
Many complexes containing triazacyclononane and
larger macrocyclic amines are known.[1,2] They are used, for
example, as bioinorganic model systems, reagents with high
metal ion selectivity or as olefin polymerisation catalysts.
The smaller N-substituted 1,3,5-triazacyclohexanes
(R3TAC) are much easier to prepare by the reaction of
formaldehyde with primary amines allowing for a large
variety of alkyl substituents. However, their coordination
chemistry has mostly been explored only in the past ten
years. A wide range of complexes with transition metals
(like titanium complex A[3] in Scheme 1) and main group
elements are well established. MAO activated chromium(iii)
complexes[4] (e.g. B in Scheme 1) are highly active homo-
geneous catalysts for the polymerisation and selective tri-
merisation of olefins.[5] Recently alternative catalysts for the
selective trimerisation of ethylene based on aryl-substituted
CpTiCl3, C, have been discovered.[6] Since many features of
the metal complexes containing R3TAC, such as the ring
centroid-metal distance, donor orbital orientation or posi-
tions of the ring substituents resemble those of analogous
Cp rather than triazacyclononane complexes, we were inter-
ested in the preparation of analogous [(R3TAC)TiCl3]+
complexes. The only previously described types of triazacy-
Scheme 1.
[a] Department of Chemistry, University of Bath,
Bath, BA2 7AY, UK
E-mail: r.d.kohn@bath.ac.uk
[b] Current address: TU Darmstadt,
64287 Darmstadt, Germany
E-mail: Kampe@ct.chemie.tu-darmstadt.de
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Scheme 2.
Eur. J. Inorg. Chem. 2005, 3217–3223
DOI: 10.1002/ejic.200500122
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3217

R. D. Köhn, P. Kampe, G. Kociok-Köhn
FULL PAPER
crystal structure of the product, 4d, revealed the same cat-
ion not with an isolated triflate anion but with the titanium
Results and Discussion
Treatment of TiCl4 with one equivalent of N-substituted containing anion [Ti2Cl6(μ-Cl)2(μ-OTf)]–. Elemental analy-
triazacyclohexanes 1 gave complex mixtures of products. sis of the bulk product indicates that a mixture of 4d and
However, a few yellow crystals of 2b grew from this mixture 3d was obtained.
as in the case of R = Ph(CH2)2 (1b). X-ray crystallography
Addition of one equivalent of LiB(C6F5)4 to a CDCl3/
revealed
a
cationic complex [(R3TAC)TiCl3]+ with SOCl2 solution of 3d leads to a significant change in the
1
[Ti2Cl10]2– anions. Apparently, excess TiCl4 can abstract chemical shift of the pair of ring CH2 signals of the H
chloride ions to produce cationic R3TAC complexes. In- NMR spectrum without changing the rest of the spectrum
deed, reaction of excess TiCl4 with 1 gave high yields of (4.96 and 4.62 ppm vs. 4.97 and 4.77 ppm in 3d) indicating
often crystalline orange compounds. The optimal ratio of an anion exchange. Preparative scale metathesis of 3 or
TiCl4 to R3TAC for a clean reaction was found to be 3:1. TiCl4/1 with LiB(C6F5)4 allows the isolation of analogous
The crystal structures of 3a, 3b and 3d contain the same salts 5 with largely B(C6F5)4 anions, although no pure sam-
cations as in 2b but with the relatively more titanium rich ples could be obtained due to anion contamination. 5d had
anions [Ti2Cl9]–. Similar ionisation of TiCl4 has previously an NMR spectrum identical to the NMR tube experiment
been observed in the reaction of hexaalkylbenzene with mentioned above and the spectra for 5b (4.91 and 4.30 ppm
three equivalents of TiCl4 giving [(arene)TiCl3][Ti2Cl9][9] vs. 5.03 and 4.81 ppm in 3b) and for 5c (3.60 and 3.45 ppm
Contrary to these arene complexes, the formation of 3 is vs. coinciding peaks at 4.83 for 3c) showed an increasing
irreversible on dilution. Thus, triazacyclohexanes are much effect of the anion exchange (up-field shift and larger sepa-
stronger ligands than the arenes. The similarity of this reac- ration) for decreasing bulk of the N-substituents. A mixture
tion and the structures of the products show that the coor- of 5b and 3b leads to NMR signals at average positions
dination chemistry of triazacyclohexanes share many char- indicating fast anion exchange on the NMR time-scale.
acteristics with cyclic π ligands in the orientation of the
The strong dependence of the ring CH2 1H NMR signals
donor orbitals, the position of the substituents near the on the anion and the solvent indicates significant interac-
plane of the donor atoms as well as the steric requirements. tions of these C–H bonds with the environment.
The well-defined complexes 3 show only limited solubil-
ity in most inert organic solvents. The isolated crystalline
solids are poorly soluble even in chlorinated solvents. The
X-ray Crystal Structures
concentrations of saturated solutions of 3a and 3d in
CH2Cl2 were found to be 2×10–4 and 2×10–3 molcm–3,
All structures contain the [(R3TAC)TiCl3]+ cation with
1
respectively, by H NMR spectroscopy. We generally find titanium containing anions. Except for one feature, struc-
low solubility of triazacyclohexane complexes, probably due tural differences between cations with different anions (2b,
to hydrogen bonding interactions between ring–CH and Cl 3b and 3d, 4d) as well as anions with different cations (3a,
of the anion (or the complex itself) found in many solid- 3b, 3d) are small and allow a separate discussion of the
state structures. Thus, long-chain N-substituents or strong anions and cations.
donor solvents are usually required for sufficient solubility.
Structural parameters of the coordination environment
The concentration of 3e was high enough to obtain 1H and around titanium in the cations [(R3TAC)TiCl3]+ shown in
19F NMR spectra in pure CDCl3 (about 4×10–3 molcm–3 Figure 1 are summarised in Table 1. The structures are very
by NMR spectroscopy). All complexes 3 dissolved well in similar to the neutral [(R3TAC)CrCl3] where the analogous
a mixture of CDCl3 and SOCl2 without apparent decompo- structure for R = PhCH2CH2 is known.[5] However, the Ti–
sition. Solutions in this mixture remained stable for many N bond (2.23 Å) is much longer than in the chromium com-
days even when exposed to air. Comparison of the NMR plex (2.10 Å) whereas the Ti–Cl bonds (2.20 Å) are shorter
spectra of 3e in neat CDCl3 and those in 1:1 CDCl3/SOCl2 than in the chromium complex (2.28 Å), despite nearly
showed little differences except for the chemical shift of the identical ionic radii for CrIII and TiIV.[11] Thus the higher
two doublets for the ring CH2 signals (4.89 and 4.74 ppm charge on titanium favours the chloride bonding over the
in CDCl3 vs. 4.98 and 4.48 ppm in CDCl3/SOCl2). The ob- amine bonding. As in other triazacyclohexane complexes
servation of these two doublets for the equatorial and axial the nitrogen lone pair cannot be directed towards the metal
hydrogen atoms in the ring is also the best evidence for κ3- and results in a bent-bonding situation. However, the Ti–N
R3TAC coordination to a metal as observed previously.[10] bonding is improved by bending the N-substituent towards
The chemical shift and shift difference appears to be highly the N3 plane and therefore the lone pair towards the metal
dependent on the environment (solvent, anion), probably as shown in Scheme 3.
due to C–H···X hydrogen bonding interactions. The shift
This bending can be expressed by the Ti–N–C angle or
difference varies from 0.1–0.9 ppm and is significantly better the distance Δ of the α-C of the N-substituent above
smaller than the difference found in the neutral imido com- (or below) the N3 plane. This can also be compared to the
plexes of type A (1–2 ppm).[3,7,8]
free ligand; the published structure[12] of 1a has severe tem-
In an attempt to obtain analogous cationic titanium perature dependent disorder between axial and equatorial
complexes with titanium free anions we added Me3SiOTf benzyl groups making it difficult to obtain reliable Δ values.
to the reaction mixture. Me3SiCl was formed, however, a We crystallised the known ligand 1e (R = p-fluorobenzyl)
3218
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Eur. J. Inorg. Chem. 2005, 3217–3223

Reaction of 1,3,5-Triazacyclohexanes with TiCl4
FULL PAPER
Scheme 3. Bent-bonding situation in triazacyclohexane complexes,
definition of Δ, and the syn and anti conformation of the N-substit-
uent.
and obtained a crystal structure without such disorder.[13]
The structure of 1e shows the most common conformation
for free triazacyclohexanes with one axial and two equato-
rial N-substituents as shown in Figure 2. Δ for the two
equatorial carbon atoms is +0.47 and +0.55 Å and close
to the value of +0.49 Å expected for a ring with perfect
tetrahedral angles and equal C–N bond lengths of 1.46 Å
(average found in 1e). The observed Δ values for the tita-
nium complexes fall into three groups: +0.12 and +0.16 Å
Figure 1. Structure of the cations in 3a, 3b and 3d. The cations in
2b and 4d look nearly identical.
Figure 2. Structure of the complex 1e.
Table 1. Selected averaged distances [Å] and angles [°] in [(R3TAC)TiCl3]+ of 2, 3 and 4.
R = PhCH2
3a
R = PhCH2CH2
2b [3b]
R = cyclohexyl
3d [4d]
Ti1–N1
Ti1–N2
Ti1–N3
av. Ti–Nsyn
av. Ti–Nanti
Ti1–Cl1
Ti1–Cl2
Ti1–Cl3
2.221(1)[b]
2.254(1)[a]
2.228(1)[b]
2.25
2.205(2)[b] [2.236(2)[b]
2.218(2)[b] [2.230(2)[b]
2.227(2)[a] [2.223(2)[b]
]
]
]
2.240(3) [2.236(2)]
2.232(3) [2.239(2)]
2.235(3) [2.227(2)]
2.24 [2.23]
2.23 [–]
2.21 [2.23]
2.22
2.201(1)
2.191(1)
2.205(1)
2.20
2.208(1) [2.206(1)]
2.206(1) [2.196(1)]
2.199(1) [2.189(1)]
2.20 [2.20]
2.197(1) [2.204(1)]
2.213(1) [2.203(1)]
2.201(1) [2.212(1)]
2.20 [2.21]
+0.04 [+0.04]
128.7(2) [128.2(1)]
+0.06 [+0.03]
128.4(2) [127.8(1)]
+0.08 [+0.05]
129.3(2) [128.2(1)]
0.06/129 [0.04/128]
av. Ti–Cl
Δ(C11)[c]
+0.02[b]
126.5(1)
+0.16[a]
133.2(1)
–0.02[b]
125.2(1)
0.16/133
0.00/126
61.7
–0.01[b] [–0.02[b]
]
Ti1–N1–C11
125.7(2) [125.7(2)]
–0.01[b] [+0.03[b]
126.1(2) [127.7(2)]
+0.12[a] [–0.07[b]
Δ(C21)[c]
]
Ti1–N2–C21
Δ(C31)[c]
]
Ti1–N3–C31
av. Δ/Ti–N–Csyn
av. Δ/Ti–N–Canti
av. N–Ti–N
av. Cl–Ti–Cl
av. Ti–N–C–Csyn
av. Ti–N–C–Canti
131.5(2) [123.4(2)]
0.12/132 [–]
–0.01/126 [–0.02/126]
62.2 [61.9]
61.9 [62.1]
104 [104]
55 [57]
106
54
173
106 [106]
75 [–]
177 [177]
177 [176]
[a] syn conformation of R. [b] anti conformation of R. [c] Distance Δ above the N3 plane (negative number on metal side).
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Eur. J. Inorg. Chem. 2005, 3217–3223
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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R. D. Köhn, P. Kampe, G. Kociok-Köhn
FULL PAPER
Figure 3. Structure of the anions in 2b, 3d and 4d. The anions in 3a and 3b look nearly identical to that in 3d.
for N-substituents in the syn conformation, –0.07 to +0.03 Table 2. Selected averaged distances [Å] and angles for the anions
of 2, 3 and 4.
(av. –0.01) Å for the anti conformation and +0.03 to +0.08
[Ti2Cl10]2– [Ti2Cl9]–
[Ti2Cl8(OTf)]–
4d
(av. +0.05) Å for the cyclohexyl substituent (β-C in both syn
and anti position). All values indicate a substantial bending
of the N-substituent position towards the N3 plane upon
complexation in order to obtain better N-metal overlap. Ti–Cl
However, steric repulsion leads to less bending in the syn
2b
3a [3b] {3d}
Ti–(μ-Cl)
2.50
2.27
2.49 [2.49] {2.49} 2.48
2.22 [2.21] {2.21} 2.21
2.10
Ti–O
Ti···Ti
Ti–(μ-Cl)–Ti
3.84
101°
3.40 [3.43] {3.39} 3.75
conformation (β-C···Cl) and increased bending in the anti
86° [87°] {86°}
78° [78°] {79°}
98° [99°] {99°}
98°
80°
99°
conformation (β-C···axial ring C–H) with an intermediate
case for cyclohexyl with repulsion at both β-C positions.
The intermediate values for the cyclohexyl substituent show
that both steric repulsions are important.
(μ-Cl)–Ti–(μ-Cl) 79°
Cl–Ti–Cl cis: 94°
It is informative to compare the bonding parameters in
these cationic [(R3TAC)TiCl3]+ complexes with the neutral
imido complexes A. The Ti–N bond lengths trans to Ti–Cl
are nearly the same (2.23 Å) unless R is the bulky tBu group
(Ͼ2.30 Å) whereas the Ti–Cl bonds are substantially
shorter in the cationic complexes (2.20 vs. 2.33–2.36 Å in A)
but similar to those in the cationic arene complexes [(arene)
TiCl3]+ (2.19 Å).[9] However, the Δ values for N-substituents
trans to Cl in the imido complexes are much larger (+0.15
to 0.24 Å) than those found in the cationic complexes
(–0.07 to +0.16 Å). Thus the tighter bonding of R3TAC in
cationic complexes is expressed as an improved nitrogen
lone pair orientation (smaller Δ) rather than shorter Ti–N
bonds.
All anions (Figure 3) contain two octahedrally coordi-
nated titanium atoms. The two metals share one edge (two
chloride bridges) in 2 or one face (three chloride bridges)
in 3. The anion in 4 contains a triflate bridge in addition
to two chloride bridges and results in structural features
intermediate between 2 and 3 as shown in Table 2. The
anions in 2 and 3 have been observed before while the anion
in 4 is new.[14]
differences between the structures. The shortest contacts in
3 with the anion increase from 3b (2.68 Å, R = PhCH2CH2)
to 3a (2.76 Å, R = PhCH2) and 3d (2.85 Å, R = cyclohexyl)
as expected for increasing steric bulk exhibited by the sub-
stituent. In the latter case as well as in the similar 4d (short-
est C–H···Cl 2.78 Å + C–H···O(Tf) 2.51 Å) additional con-
tacts of similar lengths with C–H groups of the substituents
exist. The single short C–H···Cl contact in 3b is replaced by
two slightly longer contacts of 2.73 Å (ring CH) and 2.72 Å
(α-CH2 of R) reflecting the probably tighter binding of the
Ti2Cl10 dianion.
The above study demonstrates that cationic triazacy-
clohexane complexes of titanium can be obtained by the
reaction of the ligand with excess TiCl4. The N-substituents
are more bent towards the metal than in neutral complexes
with improved metal–N bonding. The ring C–H bonds of
the triazacyclohexanes interact with the environment
through significant hydrogen-bonding interactions leading
to surprisingly poor solubility of these 3D networks in chlo-
rinated solvents.
The structures also allow us to look at the C–H···X inter-
actions in the crystal and the effect of varying the N-sub-
stituents and anions. A CSD review of C–H···Cl interac-
tions revealed H···Cl distances of 2.8–2.9 Å and C–H···Cl
angles of 140–180° as the best parameters for this hydrogen
bonding interaction when Cl is part of an anion.[15] The
structures of all complexes in this work contain C–H···Cl
contacts of this length or shorter and involve at least one
ring C–H bond. Each anion has several contacts to neigh-
bouring cations leading to an extended 3D network ratio-
Experimental Section
General Details: All manipulations of air- and moisture-sensitive
compounds were carried out under nitrogen or argon using stan-
dard Schlenk-line or glove box techniques. Solvents were dried ac-
cording to standard methods and collected by distillation. R3TAC
except for 1c are known and have been prepared analogous to the
method described for 1c. 1a,b,d,e were crystallised from petroleum
ether. 1H and 13C NMR spectra were recorded with a Varian Mer-
cury-400 or Bruker Avance-300 or 400 at 20 °C and assignments
nalising the poor solubility. However, there are noteworthy were confirmed by COSY spectra. Mr Alan Carver (University of
3220 © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3217–3223

Reaction of 1,3,5-Triazacyclohexanes with TiCl4
FULL PAPER
Bath) carried out the elemental analyses with an Exeter Analytical
Instruments CE-440 Elemental Analyser.
orange-brown precipitate was separated and dried under reduced
pressure to give a brownish yellow crystal-like powder. Yield: 1.81 g
(79%). 1H NMR (300 MHz, CDCl3/SOCl2): δ = 7.34–7.27 (9 H,
C6H5–), 7.24–7.18 (6 H, C6H5–), 4.85 and 4.81 (d, J = 9.6 Hz, 3
H, N–CH2–N), 3.21 (m, 6 H, PhEt–CH2–N) 2.68 (m, 6 H, Ph–
CH2), 1.98 (m, 6 H, PhCH2–CH2–) ppm. 13C{1H} NMR (75 MHz,
CDCl3/SOCl2): δ = 139.1 (1-C6H5), 128.7 (3-C6H5), 128.3 (2-C6H5),
126.6 (4-C6H5), 77.5 (N–CH2–N), 56.2 (PhEt–CH2–N), 32.4 (Ph–
CH2–), 25.1 (PhCH2–CH2) ppm. C30H39N3Ti3Cl12 (1010.74): calcd.
C 35.65, H 3.89, N 4.16; found C 36.0, H 3.76, N 4.24.
Phenylpropyl3TAC (1c): Phenylpropylamine (11.37 g, 84.22 mmol)
and paraformaldehyde (2.53 g, 84.22 mmol) were dissolved in tolu-
ene (50 mL). The solution was heated to distil off the produced
water as an azeotropic mixture with toluene. After 30 min the re-
maining solvent was removed by distillation under reduced pres-
sure. The remaining pale yellow oil was dissolved in methanol
(250 mL) and stored at 0 °C. The separated oil was washed with
ethanol and dried under reduced pressure to give a colourless oil.
1H NMR (300 MHz, CDCl3): δ = 7.31–7.28 (6 H, C6H5–), 7.23 (9
H, C6H5–), 3.36 (br. s, 6 H, ring–CH2), 2.69 (m, 6 H, –CH2–Ph),
2.51 (m, 6 H, N–CH2–), 1.83 (m, 6 H, Bz–CH2–CH2–N). 13C{1H}
NMR (75 MHz, CDCl3): δ = 142.1 (1-C6H5), 128.4 (3-C6H5), 128.2
(2-C6H5), 125.7 (4-C6H5), 74.5 (N–CH2–N), 52.0 (PhEt–CH2–N),
33.5 (Ph–CH2–), 29.2 (Bz–CH2–).
[(Cyclohexyl3TAC)TiCl3]+[Ti2Cl9]– (3d): A solution of Cy3TAC
(1 g, 3.00 mmol) in dichloromethane (25 mL) was added slowly to
a solution of TiCl4 (1.71 g, 9.01 mmol) in dichloromethane (25 mL)
at room temperature under a stream of dinitrogen to give a clear
brown solution. A bright yellow solid began to precipitate from
the dark solution. After 48 h in the refrigerator the precipitate was
isolated, washed with dichloromethane (20 mL) and dried under
reduced pressure to give bright yellow crystals. Yield: 2.03 g (75%).
1H NMR (300 MHz, CDCl3/SOCl2): δ = 4.97 and 4.77 (d, J = 8.8,
3 H, N–CH2–N), 3.22 [3 H, CH–N], 2.20 [6 H, eq. –CH2–CHN)],
2.00 [6 H, eq. –CH2–CH2CHN], 1.72 (3 H, eq. –CH2–
CH2CH2CHN), 1.38 [12 H, ax. –CH2–CH2–CHN] 1.2 (3 H, ax.
–CH2–CH2CH2CHN) ppm. 1H NMR (400 MHz, saturated in
CH2Cl2, 2.3 mm): δ = 4.927 and 4.85 (d, J = 8.5, 3 H, N–CH2–N),
3.2 [3 H, CH–N], 2.18 [6 H, eq. –CH2–CHN)], 1.94 [6 H, eq.
–CH2–CH2CHN], 1.70 (3 H, eq. –CH2–CH2CH2CHN), 1.34 [12
H, ax. –CH2–CH2–CHN] 1.12 (3 H, ax. –CH2–
CH2CH2CHN) ppm. 1H NMR (400 MHz, saturated in CH2Cl2/
SOCl2 (3:1), 2.8 mm): δ = 4.93 and 4.88 (3 H, N–CH2–N), 3.2 [3
H, CH–N], 2.2 [6 H, eq. –CH2–CHN)], 1.94 [6 H, eq. –CH2–
CH2CHN], 1.70 (3 H, eq. –CH2–CH2CH2CHN), 1.34 [12 H, ax.
–CH2–CH2–CHN] 1.12 (3 H, ax. –CH2–CH2CH2CHN) ppm.
13C{1H} NMR (75 MHz, CDCl3/SOCl2): δ = 74.6 (N–CH2–N),
66.6 (CH–N), 27.5 (CH2–CHN), 25.2 (CH2–CH2CHN), 24.7
(CH2–CH2CH2CHN) ppm. C21H39N3Ti3Cl12 (902.64): calcd. C
27.94, H 4.36, N 4.66; found C 27.9, H 4.35, N 4.65.
[(Benzyl3TAC)TiCl3]+[Ti2Cl9]– (3a): I A solution of (PhCH2)3TAC
(0.415 g, 1.16 mmol) in dichloromethane (25 mL) was added to a
stirred solution of TiCl4 (0.865 g, 4.56 mmol) in dichloromethane
(25 mL) at room temperature under a stream of dinitrogen. After
5 h pale yellow platelets deposited. Washing with dichloromethane
(10 mL) and drying in vacuo yielded clear yellow crystals. Yield:
0.56 g (52%). II A solution of (PhCH2)3TAC (1.24 g, 3.47 mmol)
in toluene (25 mL) was added to a stirred solution of TiCl4 (1.73 g,
9.12 mmol) in toluene (25 mL) at room temperature under a stream
of dinitrogen. Dichloromethane (50 mL) was slowly added by con-
densation under reduced pressure. After 1 h of stirring, further
TiCl4 (1.73 g, 9.12 mmol) was added to give a dark orange solution.
After another hour little orange crystals started to precipitate.
1
These were dried under reduced pressure. Yield: 1.89 g (59%). H
NMR (300 MHz, CDCl3/SOCl2): δ = 7.48 m (9 H, C6H5–), 7.30 m
(6 H, C6H5–), 5.06 and 4.14 (d, J = 9 Hz, 3 H, N–CH2–N), 4.31 (s,
1
6 H, N–CH2–Ph) ppm. H NMR (400 MHz, saturated in CH2Cl2,
0.2 mm): δ = 7.5 (9 H, C6H5–), 7.3 (6 H, C6H5–), 4.75 and 4.25 (3
H, N–CH2–N), 4.34 (s, 6 H, N–CH2–Ph). 1H NMR (400 MHz,
saturated in CH2Cl2/SOCl2, 1.0 mm): δ = 7.45 (9 H, C6H5–), 7.33
(6 H, C6H5–), 5.01 and 4.32 (d, 3 H, N–CH2–N), 4.29 (s, 6 H, N–
CH2–Ph) ppm. 13C{1H} NMR (75 MHz, CDCl3/SOCl2): δ = 130.7
(1-C6H5), 130.6 (3-C6H5), 129.9 (2-C6H5), 127.6 (4-C6H5), 76.5 (N–
CH2–N), 60.9 (Ph–CH2–N). C24H27N3Ti3Cl12 (926.58): calcd. C
31.11, H 2.94, N 4.54; found C 30.9, H 2.99, N 4.52 ppm.
[(Cyclohexyl3TAC)TiCl3]+[[Ti2Cl8(OTf)]– (4d): Trimethylsilyl tri-
fluoromethanesulfonate (0.67 mL, 3.7 mmol) was added to 5 mL
of a 0.6 m solution of TiCl4 in toluene (3 mmol) at 0 °C. The re-
sulting deep red-brown solution was stirred for 30 min and then
Cy3TAC (1.0 g, 3.0 mmol) was added at 0 °C. After warming to
ambient temperature and stirring for 1 h, hexane (30 mL) was
added to give an orange precipitate. The solution was decanted and
the residue dried under vacuum, washed with 50 mL of hexane and
dried again under vacuum to give an orange-brown solid (2.6 g,
85%). Elemental analysis (CHN) of this product fits that of a mix-
ture of complexes containing the cation with a 2:1 mixture of
[Ti2Cl8(OTf)]– and [Ti2Cl10]2– anions. Crystals of 4d were grown
from a solution in SOCl2/chloroform. 1H NMR (300 MHz, CDCl3/
SOCl2): δ = 4.92 and 4.87 (d, J = 9.4, 3 H, N–CH2–N), 3.20 [3 H,
CH–N], 2.19 [6 H, eq. –CH2–CHN)], 1.98 [6 H, eq. –CH2–
CH2CHN], 1.71 (3 H, eq. –CH2–CH2CH2CHN), 1.4 [12 H, ax.
–CH2–CH2–CHN] 1.2 (3 H, ax. –CH2–CH2CH2CHN) ppm.
13C{1H} NMR (75 MHz, CDCl3/SOCl2): δ = 77.9 (N–CH2–N),
67.0 (CH–N), 27.3 (CH2–CHN), 25.0 (CH2–CH2CHN), 24.6
(CH2–CH2CH2CHN) ppm. C22H39N3Ti3Cl11SO3F3 (1016.26):
[(Phenylethyl3TAC)TiCl3]+[Ti2Cl9]– (3b): A solution of (PhC2H4)3-
TAC (1 g, 2.5 mmol) in dichloromethane (25 mL) was added slowly
to a solution of TiCl4 (1.330 g, 7.01 mmol) in dichloromethane
(25 mL) at room temperature under a stream of dinitrogen to give
a clear brown solution. The product was cautiously precipitated
by slow addition of hexane (20 mL). After 48 h a brownish yellow
precipitate was separated and dried under reduced pressure to give
a
brownish yellow powder. Yield: 2.17 g (96%). 1H NMR
(300 MHz, CDCl3/SOCl2): δ = 7.41–7.34 (9 H, C6H5–), 7.26–7.23
(6 H, C6H5–), 5.03 and 4.81 (d, J = 9.2 Hz, 3 H, N–CH2–N), 3.55
(t, 6 H, Ph–CH2–), 2.98 (t, 6 H, Bz–CH2–N) ppm. 13C{1H} NMR
(75 MHz, CDCl3/SOCl2): δ = 135.3 (1-C6H5), 129.3 (3-C6H5), 128.5
(2-C6H5), 127.7 (4-C6H5), 77.9 (N–CH2–N), 58.1 (Bz–CH2–N),
30.5 (Ph–CH2–) ppm. C27H33N3Ti3Cl12 (968.66): calcd. C 33.48, H
3.43, N 4.34; found C 33.4, H 3.52, N 4.34.
calcd.
C 26.00, H 3.87, N 4.14. Calcd for the mixture
[(Phenylpropyl3TAC)TiCl3]+[Ti2Cl9]– (3c): A solution of (PhC3H6)3-
TAC (1 g, 2.26 mmol) in dichloromethane (25 mL) was added
slowly to a solution of TiCl4 (1.29 g, 6.80 mmol) in dichlorometh-
ane (25 mL) at room temperature under a stream of dinitrogen to
give a clear dark brown solution. The product was cautiously pre-
cipitated by slow addition of hexane (20 mL). After 24 h a dark
C22H39N3Ti2.5Cl9.5S0.5O1.5F1.5: C 30.35, H 4.52, N 4.83; found C
30.1, H 4.65, N 4.48.
[(Fluorobenzyl3TAC)TiCl3]+[Ti2Cl9]– (3e):
A solution of (p-F–
PhCH2)3TAC (0.163 g, 0.40 mmol) in dichloromethane (10 mL)
was added to a stirred solution of TiCl4 (0.16 mL, 0.28 g,
Eur. J. Inorg. Chem. 2005, 3217–3223
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3221

R. D. Köhn, P. Kampe, G. Kociok-Köhn
FULL PAPER
Table 3. Crystal data, data collection and refinement parameters for 2b, 3a, 3b, 3d and 4d.
2b·(toluene)
3a
3b
3d·(CH2Cl2)
4d
Empirical formula
M [gmol–1
C41H49Cl8N3Ti2
963.23
C24H27Cl12N3Ti3
926.54
C27H33Cl12N3Ti3
968.66
C22H41Cl14N3Ti3
987.58
C22H39Cl11F3N3O3STi3
1016.27
]
Crystal colour
yellow
yellow
yellow
yellow
yellow
Crystal size [mm]
0.4×0.25×0.2
monoclinic
P21/a (no.14)
11.3330(2)
23.7790(4)
16.6530(4)
0.45×0.38×0.38
monoclinic
P21/c (no.14)
11.6700(1)
15.7590(1)
20.5150(2)
0.4×0.33×0.2
triclinic
P1 (no.2)
0.4×0.3×0.2
monoclinic
P21/c (no.14)
13.5980(2)
10.4900(2)
28.1290(4)
0.3×0.3×0.08
triclinic
P1 (no.2)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
ß [°]
γ [°]
V [Å3]
Z
¯
¯
11.5000(4)
12.1700(5)
15.7990(7)
69.985(2)
83.7330(17)
69.130(2)
1941.09(14)
2
13.0210(2)
13.4030(2)
14.6230(2)
65.2640(8)
68.9630(9)
64.0170(8)
2034.78(5)
2
96.9650(7)
103.2280(4)
94.8570(5)
4454.66(15)
4
1.436
0.871
3672.76(5)
4
1.676
1.532
3998.00(11)
4
1.641
1.542
Dc [gcm–3
]
1.657
1.453
972
1.659
1.392
1024
μ(Mo-Kα) [mm–1
F(000)
]
1984
1848
1992
2θrange [°]
7–55
8–60
8–55
7–55
7–55
Collected data
71226
68831
21139
38570
35951
Unique data I Ͼ 2σ(I)
Refined parameter
10005, R(int) = 0.087
487
–0.560/0.903
10694, R(int) = 0.036
379
–0.891/0.778
8525, R(int) = 0.049
407
–0.513/0.533
0.0033(6)
0.0399
8970, R(int) = 0.1625
379
–1.028/0.758
9257, R(int) = 0.041
415
–0.655/0.532
min./max. density [eÅ–3
Extinction coeff.[a]
]
[b]
R1 [I Ͼ 2σ(I)]
0.0472
0.0998
1.038
0.0297
0.0700
1.047
0.0626
0.1454
1.046
0.0356
0.0908
1.049
[c]
wR2 [I Ͼ 2σ(I)]
0.0990
1.059
Gof[d]
2
2
[a] Fc* = kFc[1 + 0.001Fc2λ3/sin(2θ)]–1/4. [b] R1 = Σ||Fo| – |Fc|| / Σ|Fo|. [c] wR2 = {Σ[w(Fo – Fc2)2] / Σ[w(Fo2)2]}1/2. [d] Gof = S = {Σ[w(Fo – Fc2)2]] / (n – p)}1/2
.
1.46 mmol) in dichloromethane (20 mL) at room temperature un-
der a stream of dinitrogen. The solution was slowly concentrated
to 2 mL and cooled to –20 °C. Yellow crystals grew overnight and
Acknowledgments
We thank Prof. A. C. Filippou (HU Berlin/Germany) for dif-
were isolated by decanting the remaining solution, washing with
two 1 ml portions of CH2Cl2 and drying in a stream of nitrogen.
This results in about 1.5 or 2.5 remaining CH2Cl2 per 3e according
to elemental analysis and NMR spectroscopy, respectively. Yield:
0.29 g (74%). 1H NMR (400 MHz, saturated solution in CDCl3,
4 mm): δ = 7.40 (m, 6 H, C6H4F), 7.21 (6 H, C6H4F), 4.89 and 4.74
(d, J = 8.7 Hz, 3 H, N–CH2–N), 4.26 (s, 6 H, N–CH2–Ph) ppm.
1H NMR (400 MHz, CDCl3/SOCl2): δ = 7.38 (m, 6 H, C6H4F),
7.18 (6 H, C6H4F), 4.98 and 4.48 (d, J = 8.9 Hz, 3 H, N–CH2–N),
4.25 (s, 6 H, N–CH2–Ph) ppm. 13C{1H} NMR (101 MHz, CDCl3/
SOCl2): 164.1 (d, 1-C6H4F, J = 252 Hz), 133.4 (d, 3-C6H4F, J =
8.8 Hz), 117.2 (d, 2-C6H4F, J = 21.6 Hz), 124.0 (d, 4-C6H4F, J =
3.3 Hz), 76.7 (N–CH2–N), 59.9 (Ph–CH2–N) ppm. 19F NMR
(376 MHz, CDCl3): –108.2 ppm. 19F NMR (376 MHz, CDCl3/
SOCl2): δ = –108.2 ppm. C24H24F3N3Ti3Cl12 (980.55): calcd. C
29.40, H 2.47, N 4.29, and for 3e(CH2Cl2)1.5 (1107.95): calcd. C
27.64, H 2.46, N 3.79; found C 27.7, H 2.58, N 3.89.
fractometer time for compound 1e.
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clinic, space group P21/n, a = 9.977(2), b = 14.591(5), c =
X-ray Crystallography: Intensity data for 1e[13] were collected with
a STOE STADI4 and for 2b, 3a, 3b, 3d and 4d with a Nonius
KappaCCD diffractometer. Details of the crystal structure deter-
minations are shown in Table 3. Structure solution, followed by
full-matrix least-squares refinement was performed using the
WINGX-1.64 suite of programs throughout.[16]
CCDC-257783–257788 contain the crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Supporting Information: Plots of the C–H···Cl contacts and NMR
spectra (see also footnote on the first page of this article).
15.490(4) Å, β = 107.30(3)°, V = 2152.9(10), Z = 4, Dc
=
1.269 Mgm–3, μ(Mo-Kα) = 0.094 mm–1, T = 293 K, 6387 reflec-
3222
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3217–3223

Reaction of 1,3,5-Triazacyclohexanes with TiCl4
FULL PAPER
tions collected, 3044 unique, (Rint = 0.0304) final residuals R1[I
Ͼ 2σ(I)] = 0.0463, wR2 = 0.1068.
[14] J. Eicher, P. Klingelhöfer, U. Müller, K. Dehnicke, Z. Anorg.
Allg. Chem. 1984, 514, 79.
[16] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837.
Received: February 9, 2005
Published Online: June 17, 2005
[15] C. B. Aakeröy, T. A. Evans, K. R. Seddon, I. Pálinkó, New J.
Chem. 1999, 145.
Eur. J. Inorg. Chem. 2005, 3217–3223
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3223