1,3,2-diazaalumina-[3]ferrocenophanes with alkyn-1-yl substituents at aluminum

Article abstract of DOI:10.1515/znb-2007-1005

The 1,3,2-diazaalumina-[3]ferrocenophane-ethyl(dimethyl)amine adduct 2, containing an Al-H function, reacts with terminal alkynes R-C≡C-H [R = Bu (a), ^tBu (b), Ph (c), SiMe3 (d)] by elimination of H ₂ to the amine adducts 4a-d containing an Al-C≡C-R function. Addition of pyridine leads to the corresponding pyridine adducts 5a - d, of which the molecular structure of 5d could be determined by single crystal X-ray diffraction. The formation of 4 is accompanied by side reactions such as trimerization of the alkynes to the 1,3,5-trisubstituted benzene derivatives 6a, c, and some polymerization of the alkynes. The solution-state structures of 4 and 5 were confirmed by multinuclear magnetic resonance spectroscopy ( ¹H, ¹³C, ²⁷Al, ²⁹Si NMR). Structural features and molecular dynamics were investigated by appropriate ¹H/¹H NOE and magnetization transfer experiments, and particular attention was paid to the correct assignment of ¹³C(Al-C= C-R) NMR signals.

Full text of DOI:10.1515/znb-2007-1005

1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at
Aluminum
Bernd Wrackmeyer, Elena V. Klimkina, and Wolfgang Milius
Laboratorium fu¨r Anorganische Chemie, Universita¨t Bayreuth, D-95440 Bayreuth, Germany
Reprint requests to Prof. Dr. B. Wrackmeyer. E-mail: b.wrack@uni-bayreuth.de
Z. Naturforsch. 2007, 62b, 1259 – 1266; received May 21, 2007
The 1,3,2-diazaalumina-[3]ferrocenophane-ethyl(dimethyl)amine adduct 2, containing an Al–H
function, reacts with terminal alkynes R–C≡C–H [R = nBu (a), tBu (b), Ph (c), SiMe3 (d)] by elim-
ination of H2 to the amine adducts 4a – d containing an Al–C≡C–R function. Addition of pyridine
leads to the corresponding pyridine adducts 5a – d, of which the molecular structure of 5d could be
determined by single crystal X-ray diffraction. The formation of 4 is accompanied by side reactions
such as trimerization of the alkynes to the 1,3,5-trisubstituted benzene derivatives 6a, c, and some
polymerization of the alkynes. The solution-state structures of 4 and 5 were confirmed by multinu-
clear magnetic resonance spectroscopy (1H, 13C, 27Al, 29Si NMR). Structural features and molecular
dynamics were investigated by appropriate 1H/1H NOE and magnetization transfer experiments, and
particular attention was paid to the correct assignment of 13C(Al–C≡C–R) NMR signals.
Key words: Aluminum, Ferrocenophane, Alkynes, NMR, X-Ray
Introduction
in general in the presence of transition metal com-
plexes, can catalyze cyclotrimerization of alkynes
[9], polymerization of alkynes [10], and of course
the widely studied polymerization of olefins [11]. In
the light of these properties of aluminum hydrides,
we have studied the reactivity of the hydride 2 to-
wards four representative terminal alkynes R–C≡C–H
[R = nBu (a), tBu (b), Ph (c), SiMe3 (d)].
With a few exceptions [1] the aluminum atom in alu-
minum amides prefers the coordination number 4 and
achieves it either by dimerization [2] or by accepting a
suitable donor ligand. The latter coordination can take
place in an intra- [3] or intermolecular way [4]. Nev-
ertheless, such aluminum amides remain reactive; in
particular if they bear at least one halide or hydride
function at the aluminum atom in addition to amido
groups. Recently, we have shown that 1,3,2-diazaalum-
ina-[3]ferrocenophanes 2 and 3 are readily accessi-
ble [5] by the reaction of 1,1ꢀ-bis(trimethylsilylamino)
ferrocene 1 with H3Al–NEtMe2 [6a] (Scheme 1), in
which an Al–H bond is present, inviting a study of fur-
ther transformations.
Results and Discussion
In all cases studied (Scheme 2), we noted elimina-
tion of H2 as soon as the alkyne was added to the solu-
tion containing the aluminum hydride 2. In the case of
nBu–C≡C–H, an insoluble polymer was formed at the
same time. This is also true for Ph–C≡C–H, whereas in
t
the cases of Bu–C≡C–H and Me3Si–C≡C–H, poly-
Aluminum hydrides are well known to undergo
hydroalumination reactions with alkynes or alkenes
[7]. However, this behavior is less evident if the alu-
minum atom is coordinated to fairly strong donors such
as amines [8]. On the other hand, aluminum hydrides,
merization appears to be negligible.
Monitoring of the reactions by NMR spectroscopy
(1H, 13C and 29Si NMR) has shown that the concen-
tration of 2 decreases fast in the cases of nBu–C≡C–H
Scheme 1. Synthesis of
1,3,2-diazaalumina-[3]
ferrocenophane add-
ucts containing an
Al–H function.
0932–0776 / 07 / 1000–1259 $ 06.00 © 2007 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
Scheme 2. Conversion of the Al–H func-
tion into the Al–C≡C–R function.
Scheme 3. The formation
of the Al–C≡C–R func-
tion is accompanied by cy-
clotrimerization and poly-
merization in the cases of
the alkynes nBu–C≡C–H
and Ph–C≡C–H.
t
and Ph–C≡C–H, and rather slowly for Bu–C≡C–H talline material suitable for X-ray structural analysis
and Me3Si–C≡C–H. In the latter cases, heat- (vide infra).
ing to 75 ◦C (for tBu–C≡C–H) and 60 ◦C (for
NMR spectroscopic studies in solution
Me3Si–C≡C–H) for several hours was necessary in or-
der to accelerate and complete the reactions.
The solution-state structures of the new compounds
4 and 5 are based on a consistent set of NMR data given
in Table 1 and in the Experimental Section. The find-
ings are in agreement with the results for the solid-state
structure of 5d (vide infra).
Primary products of hydroalumination were not ob-
served. However, the reaction mixture containing 2,
tBu–C≡C–H and 4b also contained a small amount
t
of Bu–CH=CH2, most likely the result of hydroalu-
mination followed by protolytic cleavage of the Al–C=
bond [8d]. More complex reactions involving hydro-
alumination are indicated by the formation of the 1,3,5-
trisubstituted benzene derivatives 6a, c as side prod-
ucts. They were identified in the reaction mixtures by
their characteristic 13C NMR data, and in the cases of
6a, c, the formation of the trimers is accompanied by
that of polymers (Scheme 3).
For the solutions, the most important structural
1
properties were revealed by H/1H-NOE experiments
which, in the present cases, are most conveniently car-
ried out in 1D mode (Fig. 1). These phase-sensitive
pulsed gradient enhanced experiments [12] served to
prove the mutual neighborhood of the various groups
within the molecule, and they have provided evidence
for intra- and intermolecular exchange processes.
In any case, the main products, as far as the alu- Thus, the normal 1H NMR spectra of the compounds
minum compounds are concerned, are the alkyn-1- 4 can be explained by proposing either a structure with
yl derivatives 4a – d which are converted, upon addi- a planar or a non-planar arrangement of the heterocy-
tion of pyridine, into the respective pyridine adducts cle consisting of the atoms Fe,C(1),N,Al,N,C(1ꢀ), and
5a – d. All compounds 4 and 5 are extremely sensi- there is no evidence for any significant exchange with
tive to hydrolysis, and in spite of all precautions the the small amount of excess of the amine N(Et)Me2
reaction mixtures also contain variable amounts of 1. always present in solution. However, Fig. 1 shows
The pyridine adduct 5d could be isolated as crys- clearly that two dynamic processes have to be con-
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
1261
1
Fig. 1. 400 MHz 1H{ H} NOE differ-
ence spectra (gradient enhanced [12]) of
4b (10 % in [D8]toluene at 23 ◦C; re-
laxation delay 1.5 s; mixing time 0.8 s;
24 min of spectrometer time). The irradi-
ated resonance signals are marked by ar-
rows; the resulting intensities arising from
NOE or EXchange are marked. (A) Nor-
mal 1H NMR spectrum. The mixture con-
tained 4b, some 1, formed during the re-
action, tBu–C≡C–H (marked by aster-
isks), and a small amount of N(Et)Me2.
(B) The NSiMe3-resonance wasꢀ irradi-
ated and response is shown: H5,5 (+++)
ꢀ
and H2,2 (++) of the cyclopentadi-
enyl groups, NCH2 and NMe2 of the
dimethyl(ethyl)amine ligand, and the
CMe3 group. (C) The CMe3-resonance
was irradiated and response is shown:
NMe2 (+) of the N(Et)Me2 ligand, the
SiMe3 (+++) group. (D) The NMe2-
resonance of the N(Et)Me2 ligand was ir-
ꢀ
radiated and response is shown: H5,5 (+)
ꢀ
and H2,2 (+++) of the cyclopentadienyl
groups, NEt (+++) of the N(Et)Me2 lig-
and, the CMe3 (+) and the SiMe3 (+++)
group. Magnetization transfer [13] takes
place between NMe2 of the N(Et)Me2 lig-
and and NMe2 of the free N(Et)Me2, in-
ꢀ
dicating slow exchange. (E) The H2,2
-
resonance of the cyclopentadienyl groups
was irradiated and response is shown:
magnetization transfer takes place be-
ꢀ
ꢀ
tween H2,2 and H5,5 , whereaꢀs NOE is
ꢀ
observed for H4,4 (+) and H3,3 (+++) of
the cyclopentadienyl groups, NCH2 (++)
and NMe2 (+++) of the N(Et)Me2 lig-
ꢀ
and, the SiMe3 (++) group. (F) The H5,5
-
resonance of the cyclopentadienyl groups
was irradiated and response is shown:
magnetization transfer takes place be-
ꢀ
ꢀ
tween H5,5 and H2,2 , whereas NOE is
ꢀ
ꢀ
observed for H4,4 (+++) and H3,3 (+++)
of the cyclopentadienyl groups, and the
CMe3 (+) and SiMe3 (+++) group.
sidered: (i) ring inversion taking place slowly (e. g. tramolecular dynamic processes (ring inversion) in 5
exchange (EX) signꢀals as a result of magnetization are faster than for 4. Furthermore, even a very
ꢀ
transfer [13] for H2,2 and H5,5 ), proving a non-planar small amount of pyridine in excess (difficult to pre-
arrangement of the Fe,C(1),N,Al,N,C(1ꢀ) atoms, and vent owing to traces of decomposition of 5 in solu-
(ii) intermolecular exchange taking place between co- tion) causes faster exchange than the tertiary amine.
ordinated and non-coordinatedamine. The NOE exper- This gives rise to dynamically broadened 1H and
iments indicate that the N–Si bond vectors point into 13C NMR signals at r. t. As observed for 3 [5]
the same direction as the C≡C–R group, and in this or comparable Al-alkyl derivatives [14], these sig-
arrangement repulsive interactions between the SiMe3 nals would become sharper at lower temperature.
groups and the bulky amine are avoided.
However, in the case of 5, this is difficult to ob-
Since the pyridine ligand in compounds 5 is less serve in an undisturbed way, since the pyridine
bulky than the tertiary amine in compounds 4, in- adducts 5 tend to become increasingly insoluble at
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
Table 1. 13C, 29Si, and 27Al NMR dataa of the compounds 4a – d and 5b, d.
Compound
R
T (K)
4a
4b
4c
R = Ph
298
4d
5b
5d
R = nBu
R = tBu
R = SiMe3
298
R = tBu
R = SiMe3
298
298
233
2.2
106.3 106.8
66.3
69.0
64.0
63.3
298
253
298
253
3.1
106.1
67.8
δ
δ
δ
13C(SiMe3) 3.2 (56.3)
3.7 (56.2) 3.7
3.2 (56.2) 3.7 (56.3) 2.9 (55.8)
2.8 (55.6)
106.0
68.2 (br)
13C(fc-C1) 106.9
13C(fc-C2) 67.1
106.7
66.7
69.5
65.1
64.5
106.6
67.2
69.9
65.0
64.3
n. o.b
106.5
66.9
69.7
65.2
64.6
n. o.b
106.3
68.1 (br)
66.9
69.7
65.1
64.5
δ13C(fc-C5) 69.0
δ
δ
δ
13C(fc-C3) 64.8
13C(fc-C4) 64.1
13C(Al-C≡)94.5 [br]
64.8
64.6
298 K
n. o.b
95.0 [br]94.6 [br]
94.2 [br]
94.2 [br]
94.5 [br]
(25 Hz)
118.0
(h1/2, Hz)
(≈ 70 Hz)
(35 Hz) (≈ 100 Hz) (30 Hz)
(≈ 120 Hz)
δ
13C(≡C–R) 110.6 (br)
109.3 118.4 (br) 118.0
108.8 (br) 117.8 (br) 118.5 (br)
(15 Hz) (5 Hz)
117.3 (br)
(7 Hz)
0.2 (55.6)
(h1/2, Hz)
(8 Hz)
(4 Hz) (8 Hz)
13.4 31.2 (CH3) 31.0 (CH3) 125.8 (Ci) 0.1 (55.9) 31.3 (CH3)
20.2 (CH2(CH2)2CH3)19.5
22.5 (CH2CH3) 21.9
(2.5 Hz)
(6 Hz)
(5 Hz)
31.0 (CH3)
δ
13C(R)
13.8 (CH3)
28.5 (CMe3)28.3 (CMe3)127.7 (Cp)
125.5 (Cm)
28.5 (CMe3) 28.4 (CMe3)
31.4 (CH2CH2CH3) 30.5
52.1, 5.9 (NCH2CH3) 50.5, 4.952.0, 5.6
131.5 (Co)
δ13
C
51.2, 5.0
42.5
52.3, 6.0 52.0, 5.4 124.3 (Cβ) (br)124.1 (Cβ) (br)124.4 (Cβ) (br)
43.8
(EtNMe2 or 43.7 (NCH3)
42.2
43.3
43.2
137.0 (Cγ) (br) 137.0 (Cγ) (br) 136.8 (Cγ) (br)
pyridine)
149.6 (Cα) (br)149.0 (Cα) (br)148.2 (Cα) (br)
δ
27Al
120
123
–
105
120
105
(4600 Hz,
(h1/2, Hz)
(3000 Hz,
500 Hz)
4.0 (56.2)
(3000 Hz,
500 Hz)
4.1 (56.2)
(4600 Hz, (4000 Hz,
500 Hz) 500 Hz)
500 Hz)
δ
29Si
3.9
4.0 (56.2) 4.4 (56.2) 3.8 (55.8)
3.9 (55.6)
(NSiMe3)
−21.9 (55.6)
(CSiMe3)
(NSiMe3)
−21.9
(CSiMe3)
a
In CD2Cl2 (4a, 4c), [D8]toluene (4b, 4d, 5b, 5d); coupling constants ( 0.5 Hz) 1J(29Si,13C) are given in parentheses; [br] denotes broad
13C resonances of aluminum-bonded atoms; (br) denotes broad 13C resonances due to dynamic effects; n. o. = not observed.
b
1
Fig. 2. Parts of the low temperature (upper trace, 62.9 MHz) and r. t. (lower trace, 100.5 MHz) 13C{ H} NMR spectra of the
ferrocenophane 4b containing some 1, formed during the reaction, 2 and tBu–C≡C–H ([D8]toluene). The 13C(Al–C≡) NMR
signal sharpens considerably at lower temperature owing to “quadrupole decoupling” [18].
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
1263
Fig. 3. Molecular structure of 5d (A) (ORTEP plot, displacement ellipsoids at the 40 % probability level) and (B) (ball and
stick model); hydrogen atoms are omitted for clarity, see Table 2 for structural parameters.
Table 2. Selected bond lengths (pm) and angles (deg)a of the
temperatures < −20 ◦C both in [D8]toluene and
[3]ferrocenophanes 5d (Fig. 3) and 3 [5] for comparison.
CD2Cl2.
5d
3b
13C NMR data of some aluminum-nitrogen com-
pounds with terminal Al–C≡C–R functions have been
reported [15 – 17]. Unfortunately, the assignment of
the 13C(alkyne) NMR signals appears to be incorrect
in many cases [15]. Frequently the assignment of the
13C(Al–C≡) NMR signal appears to be erroneous con-
sidering the reported chemical shifts [16], or the more
readily observed slightly broadened 13C(≡C–R) NMR
signal was mistaken for that of 13C(Al–C≡). There are
also examples, where 13C NMR signals belonging un-
doubtedly to the terminal alkyne R–C≡C–H itself (see
Al–N(1)
Al–N(2)
Al–N(3) (from py)
Al–C(11)
N(1)–Si(1)
184.1(2)
183.3(3)
199.5(2)
195.7(3)
173.8(2)
174.7(2)
183.7(4)
184.0(4)
199.7(4)
–
173.9(4)
173.4(4)
–
N(2)–Si(2)
C(11)–C(12)
Si(3)–C(12)
N(1)···N(2)
C(1)···C(6)
Fe···Al
–
318.1
324.5
350.2
316.7
324.3
351.1
118.9(2)
–
N(1)–Al–N(2) (endo)
N(1)–Al–C(11)
119.9(1)
110.9(1)
110.2(1)
104.5(1)
104.8(1)
105.1(1)
116.6(2)
117.1(2)
116.0(2)
116.5(2)
125.3(1)
124.6(1)
e. g. [15b]) were wrongly assigned to the Al–C≡C– N(2)–Al–C(11)
N(3)–Al–C(11)
R unit. This confusion prompted us to look carefully
N(1)–Al–N(3) (from py)
104.2(2)
105.3(2)
119.1(3)
116.5(3)
116.3(2)
116.7(3)
122.4(2)
124.3(2)
–
for the 13C(alkyne) NMR signals in the case of com-
N(2)–Al–N(3) (from py)
C(1)–N(1)–Si(1)
C(6)–N(2)–Si(2)
Al–N(1)–C(1)
Al–N(2)–C(6)
Al–N(1)–Si(1)
Al–N(2)–Si(2)
Al–C(11)–C(12)
C(11)–C(12)–Si(3)
pounds 4 and 5. It turned out indeed that the 13C(Al–
C≡) NMR signals are expectedly rather broad (h1/2
>
80 Hz at 23 ◦C) and difficult to observe owing to fairly
long relaxation times T1(13C) and efficient scalar re-
laxation of the second kind [18, 19] (short T2(13C)).
Therefore, we show the 13C(Al–C≡C) NMR signals
of 4b as an example (Fig. 2) which may give a sort
of guidance for related studies in the field of alkyn-1-
ylaluminum chemistry.
–
Fe–C(1)–N(1)–Al–N(2)–C(6)c 12.4
Distance of Al from the plane 50.0
Fe–C(1)–N(1)–N(2)–C(6)c
12.8
51.8
C5 / C5 (α)
2.9
2.3
Single crystal X-ray diffraction of the ferrocenophane
5d
The molecular structure of 5d is shown in Fig. 3,
and selected structural parameters, in comparison with
those for the hydride 3, are given in Table 2. Inter-
molecular interactions for 5d in the solid state appear
to be negligible. The major structural properties of the
C5 / N(1) (β1)
C5 / N(2) (β2)
C5–Fe–C5 (γ)
C5 / C5 (twist) (τ)
Fe–C5 (center)
0.3 towards iron 1.6 towards iron
1.4 towards iron 0.2 towards iron
176.6
2.8
164.2
164.5
176.7
5.1
164.3
164.5
a The definition of the angles α, β, γ and τ is given in ref. [20]; b ref.
[5]; c mean deviation from plane in pm.
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
1,3,2-diazaalumina-[3]ferrocenophane unit are almost removed in vacuo, and the remaining yellow-brown oil was
dissolved in CD2Cl2 (1 mL). After separation from insol-
uble polymers, the resulting mixture contained the adducts
4a (ca. 40 %) and 2 (ca. 30 %) together with 1 and 1,3,5-
tributylbenzene 6a (1H, 13C and 29Si NMR). 4a: 1H NMR
(399.8 MHz; CD2Cl2, 298 K): δ = 0.10 (s, 18H, Me3Si),
0.85, 0.90 (t,t, 3H, 3H, CH2CH3), 1.19 (m, 2H, CCH2CH3),
unchanged when the Al–H function in 3 is replaced
by the Al–C≡C–SiMe3 function in 5d, and the solid-
state structure corresponds closely to the findings from
solution-state NMR spectra. In both 5d and 3, the sur-
roundings of the nitrogen atoms are not exactly pla-
nar (sum of bond angles 357.9◦ and 357.8◦). Devi-
ations from linearity in the Al–C≡C–SiMe3 unit are
expectedly small, and the length of the C≡C bond is
well inside the known range. Interestingly, the bond
1.47 (m, 2H, CH2CH2CH3), 2.17 (m, 2H, CH2(CH2)2CH3),
ꢀ
2.63 (s, 6H, NCH3), 3.23 (q, 2H, NCH2), 3.45 (m, 2H, H2,2 ),
ꢀ
ꢀ
ꢀ
3.76 (m, 4H, H4,4 ,3,3 ), 3.88 (m, 2H, H5,5 ).
length Al–C(11) (195.7(3) pm) in 5d is almost iden- 3,3-Dimethylbutin-1-yl derivative 4b
tical with that reported for Al–C(Me) (196.4(5) pm)
and Al–C(Et) (196.5(7) pm) of the analogous pyridine
adducts containing the Al-Me or Al-Et functions [14].
3,3-Dimethyl-1-butyne (16 mg, 0.024 mL, 0.19 mmol)
was added in excess to a solution of 2 (46 mg, 0.10 mmol)
in [D8]toluene ◦(1 mL). The reaction mixture was kept stir-
ring at 70 – 75 C for 10 h. The resulting mixture contained
the adducts 4b (ca. 70 %) together with 3,3-dimethylbut-1-
yne (20 %), 1, and free dimethyl(ethyl)amine (1H, 13C and
29Si NMR). 4b: 1H NMR (399.8 MHz; [D8]toluene; 298 K):
δ = 0.38 (s, 18H, Me3Si), 0.62 (t, 3H, CH2CH3, J = 7.6 Hz),
Experimental Section
General
All syntheses and the handling of the samples were car-
ried out observing necessary precautions to exclude traces
of air and moisture. Carefully dried solvents and oven-
dried glassware were used throughout. The deuteriated sol-
vent CD2Cl2 was distilled over CaH2 in an atmosphere
of Ar. All other solvents were distilled from Na metal
in an atmosphere of Ar. 1,1ꢀ-Diaminoferrocene [6b], 1,1ꢀ-
bis(trimethylsilylamino)ferrocene 1 [6a] and the dimethyl-
(ethyl)amine adduct of the 1,3-bis(trimethylsilyl)-1,3,2-di-
azaalumina-[3]ferrocenophane 2 [5] were prepared as de-
scribed. 1-Hexyne, 3,3-dimethyl-1-butyne, ethynylbenzene,
and ethynyl(trimethyl)silane were commercial products and
distilled prior to use. NMR measurements: Bruker ARX
250: 1H, 13C, 27Al, and 29Si NMR (refocused INEPT [21]
based on 2J(29Si,1H) = 7 Hz); Varian INOVA 400: 1H,
13C NMR; chemical shifts are given with respect to Me4Si
1.27 (s, 9H, C(CH3)3), 2.20 (s, 6H, NCH3), 2ꢀ.97 (q, 2H,
ꢀ
NCH2), ꢀ3.40 (m, 2H, H2,2 ), 3.83 (m, 2H, H4,4 ), 3.86 (m,
ꢀ
2H, H3,3 ), 4.00 (m, 2H, H5,5 ).
tBu–CH=CH2: 1H NMR (399.8 MHz; [D8]toluene;
298 K): δ = 0.95 (s, 9H, C(CH3)3), 4.83 (dd, 1H, =CH2,
2J(1H,1H) = 1.5 Hz, 3J(1H,1H)cis = 10.6 Hz), 4.90 (dd,
1H, =CH2, 2J(1H,1H) = 1.5 Hz, 3J(1H,1H)trans = 17.4 Hz),
5.77 (dd, 1H, =CH, 3J(1H,1H) = 10.6 Hz, 17.4 Hz). –
13C NMR (62.9 MHz, [D8]toluene, 298 K): δ = 28.9 (CH3),
109.2 (=CH2), 149.7 (=CH).
Phenylethynyl derivative 4c
The synthesis was carried out as described for 4a, start-
ing from 120 mg (0.26 mmol) of 2 in [D8]toluene (1.5 mL)
and ethynylbenzene (55 mg, 0.059 mL, 0.54 mmol). The
resulting mixture contained the adducts 4c (ca. 70 %) to-
gether with phenylacetylene (15 %), 1, and a small amount of
[δ1H (CHDCl2) = 5.33, δ1H (C6D5CD2H) = 2.08; δ13
C
(CD2Cl2) = 53.8, δ13C ([D8]toluene) = 20.4; δ29Si = 0 for
Ξ(29Si) = 19.867184 MHz]; external 1.1 M Al(NO3)3 in D2O
[δ27Al = 0 for Ξ(27Al) = 26.056890 MHz]. Assignments of
1H and 13C NMR signals are based on 1H/1H-NOE differ-
ence, and 2D 1H/13C-HETCOR experiments. The melting
points (uncorrected) were determined using a Bu¨chi 510 ap-
paratus.
1
unidentified olefins (1H, 13C and 29Si NMR). 4c: H NMR
(399.8 MHz; CD2Cl2, 298 K): δ = 0.17 (s, 18H, Me3Si),
1.23 (t, 3H, CH2CH3, J = 7.2 Hz), 2.71 (s, 6H, NCH3), 2.30
ꢀ
ꢀ
(q, 2H, NCH2), 3.51 (m, 2H, H2,2ꢀ ), 3.70 (m, 2H, H4,4 ), 3.80
ꢀ
(m, 2H, H3,3 ), 3.94 (m, 2H, H5,5 ), 7.25 – 7.50 (m, 5H, Ph).
Trimethylsilylethynyl derivative 4d
2-(Alkyn-1-yl)-1,3-bis(trimethylsilyl)-2-dimethyl(ethyl)-
The synthesis was carried out as described for 4b, start-
ing from 100 mg (0.22 mmol) of 2 in [D8]toluene (1.5 mL)
and trimethylsilylacetylene (32 mg, 0.046 mL,◦0.33 mmol).
amine-1,3,2-diazaalumina-[3]ferrocenophanes 4
Hexyn-1-yl derivative 4a
A solution of the dimethyl(ethyl)amine adduct of 1,3- The reaction mixture was kept stirring at 60 C for 28 h.
bis(trimethylsilyl)-1,3,2-diazaalumina-[3]ferrocenophane
2
The resulting mixture contained the adduct 4d (ca. 70 %)
(120 mg, 0.26 mmol) in toluene (5 mL) was cooled to 0 ◦C, together with 1, trimethylsilylacetylene (10 %) and free di-
and 1-hexyne (22 mg, 0.03 mL, 0.26 mmol) was added. The methyl(ethyl)amine (1H, 13C and 29Si NMR). 4d: 1H NMR
reaction mixture was allowed to reach ambient temperature (399.8 MHz; [D8]toluene; 298 K): δ = 0.24 (s, 9H, Me3SiC),
and stirring was continued for 20 h. Volatile materials were 0.38 (s, 18H, Me3SiN), 0.60 (t, 3H, CH2CH3, J = 7.2 Hz),
Unauthenticated
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B. Wrackmeyer et al. · 1,3,2-Diazaalumina-[3]ferrocenophanes with Alkyn-1-yl Substituents at Aluminum
1265
Table 3. Crystallographic data of the [3]ferrocenophane 5d.
3,3-Dimethylbutyn-1-yl derivative 5b
5d
The synthesis was carried out as described for 5a, starting
from ca. 54 mg (0.10 mmol) of 4b and pyridine (0.008 mL,
0.10 mmol), to give 51 mg of 5b (93 %). – 1H NMR
Formula
C26H40AlFeN3Si3
yellow orange prism
0.22×0.17×0.15
triclinic
Crystal
Dimensions, mm3
(399.8 MHz; [D8]toluene; 298 K): δ = 0.29 (sꢀ, 18H, Me3Si),
Crystal system
Space group
a, pm
b, pm
ꢀ
1.22 (s, 9H, ꢀC(CH3)3), 3.64 (br) (m, 4H, H2,2 ,5,5 ), 3.77 (m,
ꢀ
¯
P1
4H, H3,3 ,4,4 ), 6.62 (br) (m, 2H, Hβ ), 6.89 (br) (m, 1H, Hγ ),
1038.0(2)
1154.2(2)
1505.3(3)
8.70 (br) (m, 2H, Hα ).
c, pm
α, deg
100.62(3)
101.75(3)
108.61(3)
2
Phenylethynyl derivative 5c
β, deg
γ, deg
The synthesis was carried out as described for 5a, starting
from ca. 55 mg (0.10 mmol) of 4c and pyridine (0.008 mL,
0.10 mmol) to give a mixture containing 5c (ca. 30 %) and 1.
5c: 13C NMR (62.9 MHz, [D8]toluene, 298 K): δ = 2.7
Z
Absorption coefficient µ (mm−1
)
0.624
Diffractometer
Stoe IPDS I (MoKα radiation,
λ = 71.073 pm),
graphite monochromator
2.1 – 26.0
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
(Me3Si), 68.3 (br) (C2,2 ,5,5 ), 65.0 (C3,3 ,4,4 ), 106.0 (C1,1 ),
Measuring range (ϑ, ◦)
Reflections collected
109.2 (br) (≡C–Ph, h1/2 ≈ 15 Hz), 126.0 (Cm), 127.4 (Cp),
131.8 (Co). – 29Si NMR (49.7 MHz, [D8]toluene, 298 K):
11845
Independent reflections [I ≥ 2σ(I)] 5810
δ = 3.7.
Absorption correctiona
Refined parameters
wR2/R1 [I ≥ 2σ(I)]
None
307
0.117/0.049
Trimethylsilylethynyl derivative 5d
Max./min. residual electron density 0.56/−0.21
The synthesis was carried out as described for 5a, starting
from ca. 61 mg (0.11 mmol) of 4b and pyridine (0.009 mL,
0.11 mmol) to give 56 mg of 5b (90 %). Crystallization from
[D8]toluene, after 4 d at −30 ◦C, gave orange crystals of 5b;
(e pm−3 × 10−6
)
a
Absorption corrections did not improve the parameter set.
◦
m. p. 155 – 165 C. – 1H NMR (250.1 MHz; [D8]toluene;
ꢀ
2.19 (s, 6H, NCH3), 2.96 (q, 2H, NCH2), 3.38 (m, 2H, H2,2ꢀ ),
ꢀ
ꢀ
3.83 (m, 2H, H4,4 ), 3.85 (m, 2H, H3,3 ), 4.00 (m, 2H, H5,5 ).
298 K): δ = 0.25 (s, 9H,ꢀ Me3SiC), 0.36 (s, 18H, Me3SiN),
ꢀ
ꢀ
ꢀ
3.72 (br) (m, 4H, H2,2 ,5,5 ), 3.84 (m, 4H, H3,3 ,4,4 ), 6.58 (br)
(m, 2H, Hβ ), 6.81 (br) (m, 1H, Hγ), 8.95 (br) (m, 2H, Hα).
2-(Alkyn-1-yl)-1,3-bis(trimethylsilyl)-2-pyridine-1,3,2-
diazaalumina-[3]ferrocenophanes 5
Crystal structure determination of the [3]ferroceno-
Hexyn-1-yl derivative 5a
phane 5d
Details pertinent to the crystal structure determination are
listed in Table 3. Crystals of appropriate size were sealed un-
der argon in a Lindemann capillary, and the data collection
was carried out at 20 ◦C [22].
A solution of 4a (ca. 60 mg, 0.11 mmol) in [D8]toluene
(1 mL) was cooled to 0 ◦C, and pyridine (0.008 mL,
0.10 mmol) was added. The mixture was stirred for 1 h
and centrifuged. The resulting mixture contained ca. 40 %
of the adduct 5a together with 1. 5a: 13C NMR (62.9 MHz,
[D8]toluene, 298 K): δ = 2.5 (Me3Si), 14.0 (CH3), 19.8
(CH2(CH2)2CH3), 23.0 (CH2CH3), 31.5 (CH2CH2CH3),
Acknowledgement
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
68.0 (br) (C2,2 ,5,5 ), 64.7 (C3,3 ,4,4 ), 105.9 (C1,1 ). –
This work was supported by the Deutsche Forschungsge-
meinschaft.
29Si NMR (49.7 MHz, [D8]toluene, 298 K): δ = 3.5.
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