Titanium triamidotriamine compounds: Syntheses, structures and redox properties

Article abstract of DOI:10.1002/ejic.200400813

The preparation of 1,4,7-{NH(2-C₆H₄F)SiMe ₂}₃-1,4,7-triazacyclononane (H₃N _3-F[9]N₃) and 1,4,8-{N(H)PhSiMe₂} ₃-1,4,8-triazacycloundecane (H₃N₃[11]N ₃), and their sodium derivatives Na₃N _3-F[9]N₃(THF)₂ and Na₃N ₃[11]N₃(THF)₂, is described. The reaction of [TiCl₃(THF)₃] with Na₃N_3-F[9]-N ₃(THF)₂ and Na₃N₃[11]N ₃(THF)₂ leads to [Ti{N_3-F[9]N₃}] and (Ti(N₃[11]N₃)]. The titanium complexes react readily with I₂ to give the Ti^IV derivatives [Ti{N _3-F[9]N₃}]I and [Ti{N₃[11]N₃}]I. All titanium compounds display distorted trigonal prismatic geometries where the metal is coordinated to the six nitrogen donors. Fluxional processes that convert the conformations of the five- and six-membered metallacycles and the Δ and Λ enantiomers of [Ti{N₃[11]N₃}]I have been identified in solution. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejic.200400813

FULL PAPER
Titanium Triamidotriamine Compounds: Syntheses, Structures
and Redox Properties
Ana M. Martins,*[a] José R. Ascenso,*[a] Cristina G. de Azevedo,[a] Alberto R. Dias,[a]
M. Teresa Duarte,[a] Humberto Ferreira,[a] M. João Ferreira,[a] Rui T. Henriques,[b]
M. Amélia Lemos,[c] Li Li,[a] and João F. da Silva[a]
Keywords: Amide ligands / Cyclic voltammetry / N ligands / Titanium
The preparation of 1,4,7-{NH(2-C6H4F)SiMe2}3-1,4,7-triaza-
cyclononane (H3N3-F[9]N3) and 1,4,8-{N(H)PhSiMe2}3-1,4,8-
[Ti{N3[11]N3}]I. All titanium compounds display distorted
trigonal prismatic geometries where the metal is coordinated
triazacycloundecane (H3N3[11]N3), and their sodium deriva- to the six nitrogen donors. Fluxional processes that convert
tives Na3N3-F[9]N3(THF)2 and Na3N3[11]N3(THF)2, is de-
scribed. The reaction of [TiCl3(THF)3] with Na3N3-F[9]-
N3(THF)2 and Na3N3[11]N3(THF)2 leads to [Ti{N3-F[9]N3}]
and [Ti{N3[11]N3}]. The titanium complexes react readily
with I2 to give the TiIV derivatives [Ti{N3-F[9]N3}]I and
the conformations of the five- and six-membered metall-
acycles and the Δ and Λ enantiomers of [Ti{N3[11]N3}]I have
been identified in solution.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
placed tacn with triazacycloundecane (tacu). Although this
goal has not been attained, we describe here the syntheses
and characterisation of the new ligand precursors together
with their sodium, TiIII and TiIV derivatives. To the best of
our knowledge, Ti-tacu complexes have not been reported
before. Cyclic voltammetry results are also presented.
Introduction
The N-functionalization of azamacrocycles has been ex-
tensively explored as a method to design new ligand frame-
works for metal cations. Several substituents and synthetic
methodologies have been described and aspects such as
structures, stabilities and physical properties have been
broadly explored for many compounds. Despite the large
number of transition-metal complexes of polyaza macro-
cyclic ligands bearing functionalized pendant arms reported
in the literature,[1–3] the number of compounds displaying
Results and Discussion
The reaction sequence used to synthesize 1,4,7-[{N(H)-2-
amide-tacn fragments as metal donors is much lower.[4–8] In C6H4F}SiMe2]3-triazacyclononane (1, H3N3-F[9]N3), 1,4,8-
this context we have reported the synthesis of a new six- {N(H)PhSiMe2}3-triazacycloundecane (2, H3N3[11]N3) and
donor triamidotriamine ligand precursor derived from tacn their sodium derivatives Na3N3-F[9]N3(THF)2 (3) and
by introducing three Si(Me)2N(H)Ph pendant arms on the Na3N3[11]N3(THF)2 (4) is presented in Scheme 1. H3N3-F
-
nitrogen atoms, and the preparation and characterisation [9]N3 (1) and H3N3[11]N3 (2) were obtained in quantitative
of several triamide-tacn metal derivatives.[9,10] The ligand is yields from the corresponding triazamacrocycle trihydro-
hexacoordinate in all these complexes, irrespective of the chloride derivatives.[11,12] Na3(THF)2N3-F[9]N3 (3) and
size or oxidation state of the metals used (Ti, lanthanides, Na3(THF)2N3[11]N3 (4) were also isolated in quantitative
U). With the aim of modifying the donor properties of the yields from THF from the reaction of 1 and 2 with NaH,
original set and reduce the ligands’ hapticity, with concomi- respectively.
tant release of coordination positions at the metal centres,
The characterization data of 1–4 are consistent with their
we introduced ortho-fluorine substituents in the phenyl formulation as trisubstituted macrocycle derivatives. The
rings and increased the macrocyclic framework and re- NMR spectra of H3N3-F[9]N3 and H3N3[11]N3 reveal C3v
and C2v symmetry, respectively, compatible with fast nitro-
gen inversion of the macrocyclic amines. On the other hand,
in the proton spectra of 3 and 4 the macrocyclic resonances
are split into two groups that were identified by NOE differ-
ence experiments as the protons pointing towards the SiMe2
pendant arm groups (Hsyn) and opposite to them (Hanti).
The differentiation between syn and anti protons is indica-
tive of the coordination of the macrocyclic amines to the
[a] Centro de Química Estrutural, Complexo Interdisciplinar, Insti-
tuto Superior Técnico,
Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal
E-mail: ana.martins@ist.utl.pt
[b] Instituto Superior Técnico,
Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal
[c] Centro de Engenharia Biológica e Química, Instituto Superior
Técnico,
Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal
Eur. J. Inorg. Chem. 2005, 1689–1697
DOI: 10.1002/ejic.200400813
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A. M. Martins, J. R. Ascenso et al.
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Scheme 1. Syntheses of triazacyclononane and triazacycloundecane
ligand precursors. Cn = 0, 1; PhЈ = C6H5, o-C6H4F.
sodium cations and attests that, in these conditions, the
macrocycle nitrogen inversion is slow on the NMR time-
scale. Although we have not been able to grow crystals of
Na3(THF)2N3-F[9]N3 and Na3(THF)2N3[11]N3 suitable for
X-ray structural determination, the similarity between the
1H and 13C NMR spectra of these compounds and those
of Li3(THF)2N3[9]N3 suggests that, in solution, comparable
fluxional processes take place.[9] As shown in Scheme 2, the
fast exchange between the metals that occupy endocyclic
and exocyclic positions creates average C3 and Cs symmet-
ries for 3 and 4, respectively. In the case of the tacn deriva-
tive 3 this process makes all the pendant arms and macro-
cyclic carbons equivalent, but for 4, two sets of resonances
Scheme 2. Fluxional process responsible for the average C3 and Cs
symmetry of 3 and 4, respectively. Cn = 0, 1; PhЈ = C6H5, o-C6H4F.
Scheme 3.
owing to the pendant arms (integrating 2:1) and four car- consists of a symmetrical single line. In solution, at 22 K, a
bon macrocyclic resonances result. The 19F NMR spectrum more complex spectrum with gav = 1.953 is obtained, whose
of 1 shows a doublet at δ = –57.5 ppm, with coupling con- hyperfine structure may arise from coupling with fluorine
stant of 3.9 Hz that results from the coupling with the NH or with 47Ti and 49Ti. The spectral resolution does not al-
groups through the intramolecular formation of five-mem- low us to estimate a coupling constant but it is likely that
bered rings, as represented in Scheme 3.
it results from electron coupling to 19F given that coupling
Treatment of [TiCl3(THF)3] with one equivalent of to titanium isotopes is rarely observed and has not been
Na3(THF)2N3-F[9]N3 or Na3(THF)2N3[11]N3 in toluene led detected in the EPR spectrum of the non-fluorinated ana-
to the synthesis of [Ti{N(2-FPh)SiMe2}3(tacn)] (5, [Ti{N3-F
[9]N3}]) and [Ti{N(Ph)SiMe2}3(tacu)] (6, [Ti{N3[11]N3}]), 298 K shows a symmetrical single line, with gav = 1.944.
respectively (Scheme 4). As expected for paramagnetic com- Orange crystals of 5 and 6 were grown from toluene solu-
-
logue [Ti{N3[9]N3}].[9] The solution EPR spectrum of 6 at
1
pounds, the H NMR spectra of 5 and 6 show broad reso- tions at 4 °C. ORTEP illustrations of their molecular struc-
nances for all the protons. Large paramagnetic shifts are tures, as determined by single-crystal X-ray diffraction, are
observed for the macrocyclic protons adjacent to the nitro- represented in Figure 1 and Figure 2, respectively, and cor-
gens that appear at δ = 5.31 ppm in 5 and δ = 6.27 ppm in responding selected bond length and angles are listed in
6. The EPR spectrum of a crystal of 5 at room temperature Table 1 and Table 2.
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Titanium Triamidotriamine Compounds
FULL PAPER
Scheme 4. i) Na3N3-F[9]N3, PhЈ = o-C6H4F; ii) Na3N3[11]N3.
Figure 2. Molecular diagram of compound 6 showing the atomic
labelling scheme (ellipsoids at 30% probability level).
a consequence of the different lengths of the tacu methyl-
enic chains.
The distances between the metal and the Namine and
Namide planes are 1.65 Å and 0.88 Å in 5 and 1.15 Å and
0.91 Å in 6, respectively. The longer Ti–Ntacn distances
compared to Ti–Ntacu show the ability of the larger macro-
cycle chains to adapt to the metal–nitrogen bonding
requirements.[14] As it has a larger cavity, the triazacyclo-
undecane ring accommodates the metal cation better than
triazacyclononane and thus the metal–amine bonds become
shorter. The cooperative effects between the two types of
donor fragments is well expressed by the Ti–Namide bond
lengths, which follow the opposite trend; that is, the
Ti–Namide distances in 5 are shorter than those in 6. The
metal–nitrogen bond length variations are accompanied by
different N(i)–Si(i)–N(ij) angles, which are slightly larger in
6 than in 5. A comparison between the molecular structural
parameters of [Ti{N3-F[9]N3}] and [Ti{N3[9]N3}] shows
that the introduction of the fluorides do not alter the
metal···ligand distances significantly, nor the overall coordi-
nation geometry. However, the close F···H contacts with the
Figure 1. Molecular diagram of compound 5 showing the atomic
labelling scheme (ellipsoids at 30% probability level).
In both compounds the metal coordination geometry is Si(CH3)2 hydrogens (2.30 Å and 2.73 Å) found in 5 might
best described as distorted trigonal prismatic with three tri- have induced a more constrained structure than that of
azamacrocyclic amines and three pendant arm amides [Ti{N3[9]N3}], thus inducing the crystallization in the cubic
bonded to the titanium. Complex 5 crystallizes in the cubic space group. Other differences between the two complexes
space group P213 with twist angles between the amide and refer to the stereochemical conformation of the TiN-
amine fragments, ϑ, defined by the dihedral angles Namino
–
(CH2)2N metallacycles and to the orientation of the shift
cent1–cent2–Namido {Namine and Namide belong to the same between the Namido and Namine planes that is expressed by
pendant arm and cent1 and cent2 are the dummy centroid the twist angles defined above. The configuration of
atoms defined respectively by the three Namine [N(1), N(2), [Ti{N3[9]N3] in the solid state was shown to be Δ(λλλ)/
N(3)] and the three Namide atoms [N(11), N(21), N(31)]}[11] Λ(δδδ) whereas that of 5 is Λ(λλλ)/Δ(δδδ).
of –8.4°, whereas 6 crystallizes in the triclinic space group
The two six-membered metallacycles defined by the tita-
¯
P1 with twist angles of –21.1°, –25.8° and –32.2°. The angle nium and the NC3N chains in 6 display different conforma-
between the N(1)–N(2)–N(3) and N(11)–N(21)–N31 planes tions. The TiN(1)C(8)C(7)C(9)N(3) ring defines a chair
is 5.5° and the angle cent1–Ti–cent2 is 176.5° for 6 and, conformation while Ti(N1)C(1)C(2)C(3)N(2) has a boat
obviously, 0° and 180° for 5. The higher asymmetry re- conformation. These arrangements have also been found in
flected by these angles when compared to tacn analogues is [Cu(tacu)Br2] which is, according to a search performed in
Eur. J. Inorg. Chem. 2005, 1689–1697
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A. M. Martins, J. R. Ascenso et al.
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Table 1. Selected bond lengths [Å] and angles [°] for [Ti{N3-F[9]N3}] (5) and [Ti{N3-F[9]N3}]I (7).
5
7
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–N(11)
Ti(1)–N(21)
Ti(1)–N(31)
N(1)–C(1)
Plane[N(1)–N(2)–N(3)]–Ti(1)
Plane[N(11)–N(21)–N(31)]–Ti(1)
N(1)–Ti(1)–N(11)
N(2)–Ti(1)–N(21)
N(3)–Ti(1)–N(31)
N(1)–Ti(1)–N(2)
N(2)–Ti(1)–N(3)
N(3)–Ti(1)–N(1)
N(11)–Ti(1)–N(21)
N(11)–Ti(1)–N(31)
N(21)–Ti(1)–N(31)
Plane[N(1)–N(2)–N(3)]–Plane[N(11)–N(21)–N(31)]
[N(1)–N(2)–N(3)][a]–Ti(1)–[N(11)–N(21)–N(31)][a]
N(1)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(11)
N(2)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(21)
N(3)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(31)
2.326(3)
Ϫ
Ϫ
2.078(2)
Ϫ
Ϫ
1.490(4)
1.65(7)
0.88(7)
70.59(10)
Ϫ
Ϫ
75.21(10)
Ϫ
Ϫ
103.45(9)
Ϫ
Ϫ
0
180
–8.4
Ϫ
2.262(14)
2.259(13)
2.266(15)
1.987(13)
1.997(13)
1.969(12)
1.550(18)
1.60(9)
0.85(9)
70.1(5)
72.5(5)
70.8(5)
75.1(5)
75.4(5)
75.8(5)
103.5(5)
103.0(6)
104.5(5)
1.6
178.1
+ 16.3
+15.0
+ 14.4
Ϫ
[a] Centroid defined by the atoms in brackets.
Table 2. Selected bond lengths [Å] and angles [°] for one of the
molecules of [Ti{N3[11]N3}] (6).
The molecular structure of 7 is depicted in Figure 3 and
selected bond lengths and angles are reported in Table 1.
[Ti{N3[11]N3}]
Ti(1)–N(1)
Ti(1)–N(2)
Ti(1)–N(3)
Ti(1)–N(11)
Ti(1)–N(21)
Ti(1)–N(31)
Plane[N(1)–N(2)–N(3)]–Ti(1)
Plane[N(11)–N(21)–N(31)]–Ti(1)
N(1)–Ti(1)–N(11)
2.340(6)
2.311(5)
2.425(6)
2.074(5)
2.064(6)
2.057(6)
1.48(3)
0.90(3)
70.1(2)
N(2)–Ti(1)–N(21)
70.8(2)
N(3)–Ti(1)–N(31)
69.3(2)
N(1)–Ti(1)–N(2)
90.1(2)
N(2)–Ti(1)–N(3)
74.7(2)
N(3)–Ti(1)–N(1)
86.9(2)
N(11)–Ti(1)–N(21)
N(11)–Ti(1)–N(31)
N(21)–Ti(1)–N(31)
Plane[N(1)–N(2)–N(3)]–Plane[N(11)–N(21)–N(31)]
[N(1)–N(2)–N(3)][a]–Ti(1)–[N(11)–N(21)–N(31)][a]
N(1)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(11)
N(2)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(21)
N(3)–[N(1)–N(2)–N(3)][a]–[N(11)–N(21)–N(31)][a]–N(31)
100.0(2)
101.4(2)
105.7(2)
5.5 (3)
176.5(9)
–25.8(10)
–32.2(12)
–21.1(10)
Figure 3. Molecular diagram of the cation of compound 7 showing
the atomic labelling scheme (ellipsoids at 30% probability level).
[a] Centroid defined by the atoms in brackets.
In 7, the titanium coordination geometry is best de-
CCDC, the only triazacycloundecane complex character- scribed as distorted trigonal prismatic with twist angles, ϑ,
ised by X-ray diffraction.[15]
of 14.4°, 15.0° and 16.3°. The angle between the N(1)–
Treatment of 5 and 6 with iodine gave the corresponding N(2)–N(3) and N(11)–N(21)–N(31) planes is 1.6° and the
TiIV derivatives [Ti{N3-F[9]N3}]I (7) and [Ti{N3[11]N3}]I angle cent1–Ti–cent2 is 178.1°. The amide nitrogen atoms
(8). The 1H NMR spectrum of 7 is compatible with an are planar, with a sum of the angles around them of 359.6°
average C3 symmetry in solution where the macrocyclic pro- for N(11), 359.8° for N(21) and 360.0° for N(31). The Ti–
tons appear as two sets of resonances attributable to Hsyn Namine bond lengths range between 2.259 and 2.266 Å and
and Hanti. The 19F NMR spectrum shows a broad singlet the Ti–Namide vary from 1.969 to 1.997 Å (see Table 1). Al-
at δ = –41.2 ppm.
though slightly shorter than the values obtained for the TiIII
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Titanium Triamidotriamine Compounds
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starting material, the metal···nitrogen distances in 7 are split into five singlets and the three phenyl rings become
close to those found in cations [Ti{N3[9]N3}]X (X = I, non-equivalent, implying that the δ/λ isomerisation is
BPh4), denoting that, once more, the ortho-fluorines have blocked at that temperature. The C2 macrocyclic protons
no significant influence on the ligand coordination. Simi- pattern broadens as a consequence of the splitting into an
larly to 5, short F···H distances (2.27–2.38 Å) between the ABCD system that partially overlaps the C3 chain reso-
fluoride and the SiMe2 groups of each pendant arm are nances. The two other fluxional processes are still operative,
observed for 7. The configuration of the five-membered as revealed by the equivalence of the two methyl groups of
TiNC2N metallacycles in 7 is the same as for 5 [Λ(λλλ)/ the pendant arm bonded to the nitrogen between the two
Δ(δδδ)].
C3 macrocyclic chains. At –70 °C these protons also become
In CD2Cl2, at room temperature, the 1H NMR spectrum non-equivalent. Six different methyl resonances and the ap-
of [Ti{N3[11]N3}]I (8) is consistent with an average Cs sym- pearance of a series of interpenetrating multiplets due to
metry, displaying two sets of aromatic resonances corre- non-equivalent macrocyclic protons are indicative that the
sponding to the phenyl rings and three singlets for the six equilibrium between the two enantiomers is blocked.
CH3 groups of the bridging dimethylsilyl groups. The C2-
To evaluate the donor ability of the N3[9]N3 and N3-F[9]-
chain methylenic protons lead to different Hsyn and Hanti N3 sets used we performed cyclic voltammetry measure-
resonances at δ = 3.39 and 3.68 ppm, respectively, and the ments of complexes [Ti{N3-F[9]N3}] (5), [Ti{N3-F[9]N3}]I
C3-chain protons give rise to four multiplets centred at δ = (7) and [Ti{N3[9]N3}]X (X = I, 9, BPh4, 10)[9] in acetonitrile
2.37 and 2.05 ppm, corresponding to the Hsyn and Hanti at variable scan rates. The results are listed in Table 3.
protons of the middle of the chain, and at δ = 3.47 and
3.30 ppm corresponding to the Hsyn and Hanti protons ad-
jacent to the nitrogen atoms. This pattern reveals that the
Table 3. Electrochemical data for complexes 5, 7, 9 and 10.
red
ox
Compound[a]
E
[V]
E [V]
1/2
Solvent
three exchange processes available to the molecule at room
temperature, namely the trigonal twist of the Namine and
Namide planes, which corresponds to the equilibrium be-
tween the two possible enantiomers Δ and Λ, the δ/λ in-
terconversion of the five-membered metallacycle and the
chair/boat interconversion are fast processes on the NMR
timescale (Scheme 5). At –40 °C, the dimethylsilyl protons
1/2
[Ti{N3-F[9]N3}]
[Ti{N3-F[9]N3}]I
[Ti{N3[9]N3}] BPh4
–1.59
–0.22
CH3CN
CH3CN
CH3CN
CH2Cl2
CH3CN
–1.58
–1.71
–1.78
–1.71
[Ti{N3[9]N3}]I
–0.20
[a] At 25 °C, 6.5×10–2 m (Bu4N)BPh4, 10–3 m FeCp2. All potentials
were recorded at 200 mVs–1.
The first remark concerns the stability of the different
complexes in the medium. Triazacycloundecane derivatives
are, in general, less stable than the triazacyclononane-based
complexes and this characteristic prevents their study by
cyclic voltammetry. The stability of the cations is higher
than that of the reduced metal complexes and thus
[Ti{N3[9]N3}] and [Ti{N3[11]N3}] are not suitable starting
materials for CV measurements. Remarkably, [Ti{N3-F[9]-
N3}] is much more stable than the other TiIII compounds
and, in acetonitrile, a reversible one-electron oxidation at
ox
E
= –1.59 V was detected at a scan rate of 200 mVs–1.
1/2
Cationic tacn derivatives show reversible one-electron re-
duction peaks. Figure 4 shows the cyclic voltammogram of
[Ti{N3[9]N3}]BPh4 (10) as an example.
The values listed in Table 3 show that the redox poten-
tials for the TiIV/TiIII couple in complexes 9 and 10 are
lower than the values reported for metallocene titanium di-
chlorides such as [Cp2TiCl2], [Cp*2TiCl2] and [(C5H4-
red
SiMe3)2TiCl2], for which E values range from –1.295 to
1/2
–1.621 mV.[16–18] On the other hand, the value of –1.58 mV
red
measured for E of 7 reflects the additional stability of the
1/2
LUMO when C6H5 is replaced by o-C6H4F. The similarity
between the reduction potential of 7 and that of [Ti{O3[9]-
N3}PF6 (H3O3[9]N3 = 1,4,7-tris(5-tert-butyl-2-hydroxyben-
red
zyl)-1,4,7-triazacyclononane; E = –1.52 mV) shows that
1/2
the donor ability of the amide moieties in 7 is comparable
to that of the alkoxide fragments in [Ti{O3[9]N3}]PF6.[17]
The voltammograms of 7 and 9 display addition redox
Scheme 5. Exchange processes responsible for the average Cs sym-
metry of [Ti{N3[11]N3}]I (8).
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Figure 4. Cyclic voltammogram of [Ti{N3[9]N3}]BPh4 (10) in [Bu4N]BPh4/CH3CN, at scan rates of 200 mVs–1, 500 mVs–1 and
1000 mVs–1.
and 1,4,7-(SiMe2Cl)3-tacn[9] were prepared according to described
peaks at –0.22 V and –0.20 V, respectively, that are due to
the I– counterion.
procedures.
Cyclic voltammetric measurements were carried out with a Radi-
ometer DEA 101 Digital Electrochemical Analyser interfaced with
an IMT 102 Electrochemical Interface. [Bu4N][BPh4] (Fluka, elec-
Experimental Section
trochemical grade) was used as supporting electrolyte in CH2Cl2 or
CH3CN with a concentration of 6.5×10–2 m. All experiments were
General Procedures and Starting Materials: All reactions were con-
performed with concentrations of complexes in the range 2–
4×10–3 m. All potentials are referenced to the ferrocene/ferrocen-
ium couple as internal standard with E1/2 = 0.50 V vs. S.C.E. A Pt
disc (φ = 1 mm) was used as working electrode. The solvents were
distilled immediately before use. All experiments were carried out
at 25 °C in the absence of oxygen. Dry nitrogen was bubbled
through the solution in the cell before measurements.
ducted under a nitrogen atmosphere. Solvents were pre-dried with
4 Å molecular sieves and refluxed over sodium-benzophenone (di-
ethyl ether, tetrahydrofuran, n-hexane and toluene) or calcium hy-
dride (dichloromethane) under an atmosphere of nitrogen, and col-
lected by distillation. Deuterated solvents were dried with molecu-
lar sieves and freeze-pump-thaw degassed prior to use. Proton
(300 MHz) and carbon (75.419 MHz) NMR spectra were recorded
with a Varian Unity 300, at 298 K, unless stated otherwise. The
spectra are referenced to internal residual protio-solvent (1H) or
solvent (13C) resonances and reported relative to tetramethylsilane
(δ = 0 ppm). Assignments were supported by NOE difference ex-
periments and by 13C-1H hetero-correlations, as appropriate. EPR
spectra were recorded at room temperature with a Bruker 300E
spectrometer at X-band frequency (ν Ϸ 9.5 GHz). Mass spectra
were performed at the Laboratoire de Spectrométrie de Masse,
Université de Rouen, France. Elemental analyses were obtained
from the Laboratório de Análises do IST, Lisbon, Portugal.
1,4,7-[{N(H)(2-C6H4F)}SiMe2]3-tacn (1): 2-Fluoraniline (2.1 mL,
21.9 mmol) was added to a suspension of NaH (0.95 g, 39.6 mmol)
in THF. The mixture was heated to 60 °C and stirred for 12 h. The
excess of NaH was filtered off and washed with 20 mL of THF, at
room temperature. The filtrates were added dropwise to a solution
of 1,4,7-(SiMe2Cl)3-tacn (2.74 g, 6.74 mmol) in toluene (80 mL),
cooled to –40 °C. The mixture was warmed to room temperature
and stirred for 12 h. The solvents were evaporated and the residue
was extracted in hexane and filtered. Evaporation to dryness led to
a very viscous yellow oil in quantitative yield (4.25 g). 1H NMR
(C6D6): δ = 6.94–6.90 (m, 3 H, Hmeta), 6.88–6.87 (m, 3 H, Hmeta),
6.85–6.82 (m, 3 H, Hortho), 6.55–6.48 (m, 3 H, Hpara), 3.77 (d, JH,F
= 3.9 Hz, 3 H, NH), 2.89 (s, 12 H, NCH2CH2N), 0.09 (s, 18 H,
Triethylamine, aniline, SiMe2Cl2, TiCl3 and NaH (60% dispersion
in mineral oil) were purchased from Aldrich. NEt3 and NH2Ph
were pre-dried with molecular sieves, refluxed over calcium hydride,
and collected by distillation. SiMe2Cl2 was purified by removal of
residual HCl and then distilled trap-to-trap. NaH was washed with
1
CH3) ppm. 13C{1H} NMR (C6D6): δ = 153.1 (d, JC,F = 236.0 Hz,
2
4
Cortho), 135.8 (d, JC,F = 13.0 Hz, Cipso), 124.8 (d, JC,F = 3.5 Hz,
3
3
THF prior to use. [TiCl3(THF)3],[19] tacn·3HCl,[11] tacu·3HCl,[12] Cmeta), 118.0 (d, JC,F = 7.0 Hz, Cpara), 117.2 (d, JC,F = 3.5 Hz,
1694 © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1689–1697

Titanium Triamidotriamine Compounds
FULL PAPER
1,4,8-[{N(Na)(C6H5)SiMe2}3-tacu]·2THF (4): A solution of 1,4,8-
2
Cortho), 115.3 (d, JC,F = 20.0 Hz, Cmeta), 50.5 (NCH2CH2N), –1.4
(CH3) ppm. 19F NMR (C6D6): δ = –57.47 ppm. C30H45N6F3Si3 [N(H)(C6H5)SiMe2]3-tacu (7.03 g, 11.62 mmol) in THF (ca. 25 mL)
(630.98): calcd. C 57.08, H 7.19, N 13.33; found C 57.06, H 7.20,
was added to a suspension of NaH (1.00 g, 42 mmol) in 100 mL of
THF. The mixture was slowly warmed to 60 °C and stirred at this
temperature for 12 h. After cooling to room temperature, the solu-
tion was filtered off and the NaH excess was washed with 30 mL
of THF that was collected with the filtrate. The solvent was evapo-
rated to dryness and a greenish powder was obtained by scratching
the dried material under N2, at liquid nitrogen temperature. Yield:
N 13.20. MS (EI): m/z = 630 [M]+.
1,4,8-[SiMe2Cl]3-tacu:
A
suspension of tacu·3HCl (1.06 g,
3.97 mmol) in CH2Cl2 (50 mL), cooled to 0 °C, was treated with
Et3N (6,0 mL, 40 mmol). The mixture was stirred during 15 min-
utes and SiMe2Cl2 (3.0 mL, 24 mmol) was added. The reaction pro-
ceeded overnight at room temperature and a precipitate formed.
The volatiles were then evaporated under vacuum and the residue
was extracted with hexane and filtered. Evaporation of the hexane
led to a white solid in quantitative yield (1.72 g). The reaction was
scaled up to 20 mmol of tacu·3HCl. 1H NMR (C6D6): δ =
1
3
8.63 g, quantitative. H NMR (C6D6): δ = 7.16 (t, JH,H = 7.2 Hz,
3
3
2 H, Hmeta), 7.07 (t, JH,H = 6.9 Hz, 4 H, Hmeta), 6.76 (t, JH,H
=
3
7.2 Hz, 6 H, Hortho), 6.58 (t, JH,H = 7.2 Hz, 1 H, Hpara), 6.47 (t,
3JH,H = 6.9 Hz, 2 H, Hpara), 3.27 (m, 8 H, OCH2, THF), 2.86 [br.
s, 6 H, NCHsynHantiCH2CHsynHantiN(CHsynHanti)2N], 2.56 [br. s, 2
3
2.90 (s, 4 H, NCH2CH2N), 2.83 [t, JH,H = 6.9 Hz, 4 H,
3
H, N(CHsynHanti)2N], 2.44 (br. s, 4 H, NCHsynHantiCH2CHsyn-
N(CH2)2CH2N(CH2)2N], 2.65 [t, JH,H = 6.9 Hz, 4 H, (CH2)2-
3
HantiN), 1.67 (br. s, 2 H, NCH2CHsynHantiCH2N), 1.38 (br. s, 2 H,
NCH2CHsynHantiCH2N), 1.24 (m, 8 H, CH2, THF), 0.34 (s, 6 H,
SiCH3), 0.29 (s, 12 H, SiCH3) ppm. 13C{1H} NMR (C6D6): δ =
161.1 (1 C, Cipso), 160.4 (2 C, Cipso), 130.7 (4 C, Cmeta), 130.2 (2 C,
CH2NCH2(CH2)2], 1.53 (quint., JH,H
=
6.9 Hz,
4
H,
NCH2CH2CH2N), 0.29 (s, 12 H, SiCH3), 0.27 (s, 6 H, SiCH3) ppm.
13C{1H} NMR (C6D6): δ = 50.4 (NCH2CH2N), 46.2 [(CH2)2CH2-
NCH2(CH2)2], 45.7 [N(CH2)2CH2N(CH2)2N], 30.8 (NCH2CH2-
CH2N), 2.3 [(CH2)3N{Si(CH3)2}(CH2)3], 2.1 [(CH2)3N{Si(CH3)2}-
(CH2)2] ppm. C14H34N3Cl3Si3 (435.06): calcd. C 38.63, H 7.88, N
9.66; found C 38.55, H 7.96, N 9.55. MS (EI): m/z = 401 [M –
Cl]+.
Cmeta), 122.9 (2 C, Cortho), 121.8 (4 C, Cortho), 113.3 (1 C, Cpara),
113.2 (2 C, Cpara), 67.8 (OCH2, THF), 51.4 [(CH2)2CH2-
NCH2(CH2)2], 50.7 [N(CH2)2CH2N(CH2)2N], 49.0 [N(CH2)2N],
30.0 (NCH2CH2CH2N), 25.5 (CH2, THF), 1.2 [(CH2)3N{Si-
(CH3)2}(CH2)3], 0.1 [(CH2)3N{Si(CH3)2}(CH2)2] ppm.
1,4,8-[N(H)(C6H5)SiMe2]3-tacu (2): PhNH2 (6.8 mL, 74 mmol) was
added at 0 °C to a suspension of NaH (2.32 g, 93 mmol) in 100 mL
of THF. The cooling bath was removed and, once the initial effer-
vescence had stopped, the mixture was warmed at 60 °C for 12 h.
The solution was filtered and the residue washed with THF
(20 mL). The solution was transferred dropwise, at –40 °C, to a
solution of 1,4,8-[ClSiMe2]3-tacu (10.24 g, 23.54 mmol) in 100 mL
of toluene. The reaction took place at room temperature during
12 h and the volatiles were then evaporated. The residue was ex-
tracted with hexane and filtered off. Evaporation of the solvent led
[Ti{N(2-C6H4F)SiMe2}3-tacn] (5): A solution of [1,4,7-{N(Na)(2-
C6H4F)SiMe2}3-tacn]·2THF (2.30 g, 2.86 mmol) in toluene
(10 mL) was rapidly added at –60 °C to
a suspension of
[TiCl3(THF)3] (1.11 g, 3.00 mmol) in toluene (40 mL). The mixture
was allowed to warm to room temperature while being stirred for
12 h. The solution was filtered through a celite layer and the residue
was washed with toluene and collected together with the filtrate.
The solvents were evaporated under vacuum and the compound
was washed at –30 °C with hexane (2×5 mL). Yield: 90% (1.69 g).
1H NMR (C6D6): δ = 9.25, 7.98, 6.93 (br., 2-C6H4F), 5.30 (br.,
NCH2CH2N), 0.61 [br., Si(CH3)2] ppm. EPR (10–2 m in toluene,
22 K): g = 1.953. C30H42F3N6Si3Ti (675.82): calcd. C 53.29, H 6.27,
N 12.44; found C 53.20, H 6.36, N 12.43. MS (EI): m/z = 583
[M+ – C6H2F].
1
to 14.23 g of 2 (100%). H NMR (C6D6): δ = 7.20–7.13 (m, 6 H,
3
Hmeta), 6.81–6.73 (m, 3 H, Hpara), 6.67 (d, JH,H = 8.9 Hz, 4 H,
3
Hortho), 6.60 (d, JH,H = 8.9 Hz, 2 H, Hortho), 3.15 (s, 2 H, NH),
3
3.12 (s, 1 H, NH), 3.02 (s, 4 H, NCH2CH2N), 2.73 [t, JH,H
=
3
6.9 Hz, 4 H, (CH2)2CH2NCH2(CH2)2], 2.39 [t, JH,H = 6.9 Hz, 4
H, N(CH2)2CH2N(CH2)2N], 1.63 (quint., JH,H = 6.9 Hz, 4 H,
3
[Ti{N(Ph)SiMe2}3-tacu] (6): A suspension of [TiCl3(THF)3] (1.23 g,
3.31 mmol) in 50 mL of toluene was treated at –60 °C with a solu-
NCH2CH2CH2N), 0.12 (s, 12 H, SiCH3), 0.08 (s, 6 H, SiCH3) ppm.
13C{1H} NMR (C6D6): δ = 147.4 (3 C, Cipso), 129.5 (2 C, Cmeta),
129.4 (4 C, Cmeta), 118.3 (2 C, Cpara), 118.2 (1 C, Cpara), 116.9
tion
of
1,4,8-[{N(Na)(C6H5)SiMe2}3-tacu]·2THF
(2.36 g,
3.18 mmol) in 10 mL of toluene. The mixture was allowed to reach
room temperature and was stirred for a further 12 h. The solution
was filtered through a celite layer and the solvent evaporated to
dryness. The solid obtained was washed at –30 °C with hexane and
dried. Crystals suitable for X-ray diffraction were obtained from
toluene at 4 °C. Yield: 80% (1.65 g). EPR (10–2 m in toluene, 22 K):
g = 1.944. C32H49N6Si3Ti (649.90): calcd. C 59.11, H 7.60, N 12.94;
found C 59.03, H 7.73, N 12.88. MS (EI): m/z = 649 [M]+.
(4 C,
Cortho), 116.8 (2 C, Cortho), 50.2 (NCH2CH2N), 46.7
[(CH2)2CH2NCH2(CH2)2], 45.3 [N(CH2)2CH2N(CH2)2N], 32.0
(NCH2CH2CH2N), –1.05 [(CH2)3N{Si(CH3)2}(CH2)3], –1.08
[(CH2)3N{Si(CH3)2}(CH2)2] ppm. C32H52N6Si3 (605.06): calcd. C
63.50, H 8.67, N 13.90; found C 63.75, H 8.61, N 13.86. MS (EI):
m/z = 604 [M]+.
[1,4,7-{N(Na)(2-C6H4F)SiMe2}3-tacn]·2THF (3):
A solution of
1,4,7-{[N(H)(2-C6H4F)]SiMe2}3-tacn (7.91 g, 12.54 mmol) in THF
(25 mL) was added dropwise to a suspension of NaH (1.2 g,
50 mmol) in THF (100 mL). The mixture was then heated at 60 °C
for 12 h. The solution was filtered off and the excess of NaH was
washed with THF (30 mL). Evaporation of the THF led to a green-
[Ti{N(2-C6H4F)SiMe2}3-tacn]I (7): A solution of [Ti{N(2-C6H4F)
SiMe2}3-tacn] (0.80 g, 1.19 mmol) in 40 mL of toluene, cooled to
–60 °C, was treated with I2 (0.15 g, 0.60 mmol). The solution was
allowed to warm to room temperature and was then stirred for
12 h. The solvent was evaporated to dryness and the residue was
1
ish solid in quantitative yield (10.54 g). H NMR (C6D6): δ = 6.94
3
(m, 6 H, Hortho, Hmeta), 6.84 (t, JH,H = 6.6 Hz, 3 H, Hmeta), 6.24 washed with hexane and dried in vacuo to give 7 as an orange solid
(m, 3 H, Hpara), 3.41 (m, 8 H, OCH2, THF), 3.07–2.95 (m, 6 H, in 98% yield (0.93 g). 1H NMR (C6D5Br):
CH2, syn), 2.75–2.63 (m, 6 H, CH2, anti), 1.30 (m, 8 H, CH2, THF), (br. t, 3 H, Hmeta-H3), 7.30–7.20 (m, 3 H, Hpara), 6.95 (t, JH,H
δ
=
7.37
3
3
0.28 (s, 18 H, CH3) ppm. 13C{1H} NMR (C6D6): δ = 158.1 (d,
= 6.6 Hz, 3 H, Hmeta-H5), 5.76 (t, JH,H = 7.2 Hz, 3 H, Hortho),
1JC,F = 225.0 Hz, Cortho), 149.5 (br., Cipso), 125.1 (Cmeta), 124.3 4.65–4.40 (br. s, CHantiHsyn), 3.95–3.75 (m, 6 H, CHantiHsyn), 0.72
2
3
3
(Cortho), 114.4 (d, JC,F = 24.0 Hz, Cmeta), 110.3 (Cpara), 67.9
(OCH2, THF), 48.3 (NCH2CH2N), 25.6 (CH2, THF), 0.1 (CH3) = 8.4, JH,H = 1.5 Hz, 3 H, Hmeta-H3), 7.02–6.93 (m, 3 H, Hpara),
ppm. 19F NMR(C6D6): δ = –63.24 (m) ppm. 6.52 (dt, 3JH,H = 7.8, 5JH,F = 1.5 Hz, 3 H, Hmeta-H5), 5.43 (dt, 3JH,H
(s, 18 H, CH3) ppm; (CD3CN): δ = 7.09 (ddd, JH,F = 11.4, JH,H
4
Eur. J. Inorg. Chem. 2005, 1689–1697
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1695

A. M. Martins, J. R. Ascenso et al.
FULL PAPER
Table 4. Crystal and refinement data for compounds 5 and 7.
5
7
Empirical formula
Formula mass
Temperature
C30H42F3N6Si3Ti
675.87
293(2) K
C30H42F3IN6Si3Ti
802.77
293(2) K
Wavelength
0.71069 Å
0.71069 Å
Crystal system
Space group
Unit cell dimensions
cubic
P213
orthorhombic
P21cn
a = 10.577(5) Å
b = 17.772(5) Å
c = 18.911(5) Å
3555(2) Å3
a = 15.080(2) Å
b = 15.0780(16) Å
c = 15.0753(16) Å
3427.7(7) Å3
4
Volume
Z
Calculated density
Absorption coefficient
F(000)
4
1.310 Mgm–3
1.500 Mgm–3
1.256 mm–1
0.401 mm–1
1420
1632
Crystal size
Crystal morphology
Colour
prism
0.5×0.3×0.3 mm
red
parallelepiped
0.6×0.4×0.3 mm
red
Theta range for data collection
Limiting indices
1.91 to 26.00°
0 Յ h Յ 18
0 Յ k Յ 18
1.57 to 25.97°
0 Յ h Յ 13
0 Յ k Յ 21
–18 Յ l Յ 18
7249/2262 [R(int) = 0.0489]
99.7% (θ = 26.00)
full-matrix least-squares on F2
2262/0/131
0 Յ l Յ 23
Reflections collected/unique
Completeness to theta
Refinement method
3603/3603 [R(int) = 0.0000]
97.8% (θ = 25.97)
full-matrix least-squares on F2
3603/1/392
Data/restraints/parameters
Goodness-of-fit on F2
1.073
1.074
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
R1 = 0.0400, wR2 = 0.0892
R1 = 0.0593, wR2 = 0.1007
0.46(5)
R1 = 0.0984, wR2 = 0.2247
R1 = 0.1365, wR2 = 0.2663
0.08(7)
0.215 and –0.196 eÅ–3
3.954 and –2.026 eÅ–3
4
4
= 7.8, JH,F = 7.8, JH,H = 2.1 Hz, 3 H, Hortho), 3.63 (s, 12 H,
NCH2CH2N), 0.42 (s, 18 H, CH3) ppm. 13C{1H} NMR (CD3CN):
Table 5. Crystal and refinement data for compound 6.
6
1
2
δ = 154.8 (d, JC,F = 241.0 Hz, Cortho), 140.7 (d, JH,F = 13.0 Hz,
Cipso), 127.3 (Cortho), 126.3 (d, 3JC,F = 7.3 Hz, Cpara), 125.5 (d, 4JC,F
Empirical formula
Formula mass
Temperature
Wavelength
Crystal system
Space group
C32H49N6Si3Ti
649.94
2
=
3.7 Hz, Cmeta), 116.9 (d, JC,F
=
22 Hz, Cmeta), 52.4
(NCH2CH2N), –0.7 (CH3) ppm. 19F NMR(CD3CN): δ = –41.06
(m) ppm. C30H42F3IN6Si3Ti (802.72): calcd. C 44.86, H 5.27, N
10.47; found C 44.68, H 5.27, N 10.37. MS (EI): m/z = 675
[M – I]+.
293(2) K
1.54180 Å
triclinic
¯
P1
Unit cell dimensions
a = 10.497(3) Å
b = 18.309(6) Å
c = 18.355(3) Å
3481.6(16) Å3
2 (2 molecules)
1.240 Mgm–3
3.304 mm–1
[Ti{N(Ph)SiMe2}3-tacu]I (8): A solution of [Ti{N(Ph)SiMe2}3-tacu]
(3.25 g, 5.0 mmol) in toluene at –60 °C was treated with I2 (0.69 g,
2.7 mmol). The solution was allowed to warm to room temperature
and was then stirred for 12 h. The solvent was removed in vacuo
and the residue was washed with hexane (3×5 mL) and dried. The
Volume
Z
Calculated density
Absorption coefficient
F(000)
1
complex was obtained as an orange solid in 96% yield (3.72 g). H
NMR (CD2Cl2, room temp.): δ = 7.14 (t, JH,H = 7.5 Hz, 2 H,
1388
3
Crystal morphology
Crystal size
Colour
prism
0.6×0.3×0.2 mm
orange
3
Hmeta), 6.91 (m, 4 H, Hmeta), 6.68 (m, 3 H, Hpara), 6.49 (d, JH,H
=
7.5 Hz, 2 H, Hortho), 6.25 (d, 3JH,H = 7.8 Hz, 4 H, Hortho), 3.68, 3.39
(br., 4 H, NCH2CH2N), 3.47, 3.30 (m, 8 H, NCH2CH2CH2N),
2.37, 2.05 (br., m, 4 H, NCH2CH2CH2N), 0.70 (s, 6 H, CH3), 0.46
Theta range for data collection
Limiting indices
3.25 to 66.93°
–12 Յ h Յ 0
–21 Յ k Յ 21
–21 Յ l Յ 21
13100/12362 [R(int) =
0.0721]
99.8% (θ = 66.93)
full-matrix least-squares on
F2
1
(s, 6 H, CH3), 0.21 (br. s, 6 H, CH3) ppm. H NMR (CD2Cl2, –40
°C): δ = 7.10 (m, 2 H, Hmeta), 6.97–6.84 (m, 4 H, Hmeta), 6.69–6.23
(m, 3 H, Hpara), 6.51 (d, 3JH,H = 7.8 Hz, 2 H, Hortho), 6.40 (d, 3JH,H
Reflections collected/unique
Completeness to theta
Refinement method
3
= 7.8 Hz, 2 H, Hortho), 6.23 (d, JH,H = 8.1 Hz, 2 H, Hortho), 3.70–
3.14 (br. m, 12 H, NCH2), 2.10, 1.89 (br. m,
NCH2CH2CH2N), 0.83 (s, 3 H, CH3), 0.75 (s, 3 H, CH3), 0.43 (s,
6 H, CH3), 0.21 (s, 3 H, CH3), 0.12 (s, 3 H, CH3) ppm. H NMR
(CD2Cl2, –70 °C): δ = 7.08 (m, 2 H, Hmeta), 6.94 (m, 2 H, Hmeta),
6.83 (m, 2 H, Hmeta), 6.67–6.51 (m, 7 H, Hpara, Hortho), 6.25 (br. d,
2 H, Hortho), 3.70–3.06 (br. m, 12 H, NCH2), 2.07, 1.76 (br. m, 4
H, NCH2CH2CH2N), 0.95 (s, 3 H, CH3), 0.78 (s, 3 H, CH3), 0.44
4 H,
1
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
12362/0/758
0.987
R1 = 0.0908, wR2 = 0.2300
R1 = 0.1767, wR2 = 0.2726
0.625 and –0.551 eÅ–3
Largest diff. peak and hole
1696
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1689–1697

Titanium Triamidotriamine Compounds
FULL PAPER
[2]
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1998, 174, 417–468.
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org. Chim. Acta 2003, 351, 404–408.
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Chem. Commun. 2003, 1025–1033.
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Hessen, J. H. Teuben, Organometallics 2004, 23, 936–939.
S. Bambirra, S. J. Boot, D. van Leusen, A. Meetsma, B.
Hessen, Organometallics 2004, 23, 1891–1898.
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Duarte, R. T. Henriques, Inorg. Chem. 2003, 42, 2675–2682.
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Martins, Â. Domingos, N. Marques, Inorg. Chem. 2003, 42,
4223–4231.
(s, 3 H, CH3), 0.38 (s, 3 H, CH3), 0.21 (s, 3 H, CH3), 0.09 (s, 3 H,
CH3) ppm. 13C{1H} NMR (CD2Cl2, room temp.): δ = 159.0, 152.8
(Cipso), 129.6, 128.8, 124.1, 122.9, 119.7, 118.6 (CPh), 52.6, 50.7,
48.3 (NCH2), 26.7 (NCH2CH2CH2N), 1.8 (CH3), 1.1 (CH3), 0.0
(CH3) ppm. C32H49IN6Si3Ti (776.80): calcd. C 49.48, H 6.36, N
10.82; found C 49.18, H 6.27, N 10.39.
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
X-ray Experimental Details: X-ray data were collected on a
MACH3 Nonius diffractometer equipped with Mo-Kα radiation (λ
= 0.71069 Å) and a Turbo CAD4 with a rotating anode and Cu-
Kα1 radiation (in the case of compound 7), at room temperature.
Solution and refinement were performed with SIR97[20] and
SHELXL[21] included in the WINGX Version 1.64.03b program
package.[22] Compound 5 crystallized in the cubic space group
P213, thus only 1/3 of the molecule is present in the asymmetric
unit, as the Ti atom is on a 3-fold rotation axis. Compound 6 crys-
¯
tallized in the triclinic centrosymmetric space group P1 with two
similar molecules in the asymmetric unit. Geometrical data are dis-
cussed and presented only for one of the molecules. As for com-
pound 7, a large residual electron density is present near the iodide
atom. Several refinements of a possible disorder of I– (occupying
three possible positions with different occupation factors) did not
improve the refinement and several satellite residual peaks were
kept. The possibility of a disordered I3– ion was also attempted but
the I–I distances were not acceptable. All non-H atoms were refined
anisotropically, and all hydrogen atoms were inserted in idealized
positions riding on the parent C atom. All the details concerning
data collection and refinement are presented in Table 4 and Table 5.
Figures were drawn with ORTEP3.[23]
[11]
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CCDC-250633 to -250635 (for 5–7, respectively) contain the sup-
plementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
The authors are thankful to the Fundação para a Ciência e a Tec-
nologia, Portugal for funding this work (research projects POCTI/
QUI/39734/2001 and POCTI/QUI/46206/2002).
[23] ORTEP3: L. J. Farrugia, J. Appl. Crystallogr. 1997, 30, 565–
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[1] J. Costamagna, G. Ferraudi, B. Matsuhiro, M. C. Vallette, J.
Canales, M. Villagrán, J. Vargas, M. Aguirre, Coord. Chem.
Rev. 2000, 196, 125–164.
Received: September 28, 2004
Eur. J. Inorg. Chem. 2005, 1689–1697
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1697