Organometallics
Article
4,5-anth), 6.43 (d, 4H, 3JHH = 3.4 Hz, pyrrole β-H), 5.72 (d, 4H, 3JHH
= 3.4 Hz, pyrrole β-H), 5.69 (s, 2H, meso-H). Data for the minor
isomer are as follows. H NMR (d8-THF, 300 K): δH/ppm 8.56 (s,
the macrocyclic frameworks means that unusual planar oxo and
cyclic hydroxo tetranuclear zinc complexes are formed cleanly,
without decomposition to extended aggregates. In a manner
similar to our previous work on macrocycle encapsulated
magnesium hydroxide cubanes, it is clear that these macrocylic
ligands can flex to accommodate small Zn(OH/O) clusters and
limit further cluster growth. We are currently expanding this
chemistry to redox-active first-row transition metals.
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2H, 9-anth), 8.00 (s, 4H, imine), 7.77 (s, 2H, 10-anth), 7.24 (d, 4H,
3JHH = 8.6 Hz, 2,7-anth), 6.84 (t, 4H, 3JHH = 10 Hz, 3,6-anth), 6.70 (d,
4H, 3JHH = 6.7 Hz, 4,5-anth), 6.32 (d, 4H, 3JHH = 3.4 Hz, pyrrole β-H),
3
6.06 (d, 4H, JHH = 3.4 Hz, pyrrole β-H), 5.99 (s, 2H, meso-H).
13C{1H} NMR (d8-THF, 300 K): δC/ppm 158.56, 148.53, 146.2 (d,
1JCF = 249 Hz, ArF), 141.2 (d, 1JCF = 244 Hz, ArF), 138.6 (d, 1JCF = 260
Hz, ArF), 135.38, 134.09, 133.13, 129.08, 127.34, 127.18, 126.73,
124.83, 119.22, 117.67, 115.65, 112.58, 36.25. Data for the major
isomer are as follows. 19F{1H} NMR (d8-THF, 300 K): δF/ppm
EXPERIMENTAL SECTION
■
General Procedures. Syntheses of all compounds were carried out
under a N2 atmosphere using standard Schlenk-line techniques.
Ligands H4La and H4Lb were prepared according to literature
procedures.30 Vacuum Atmospheres and MBraun gloveboxes were
used to manipulate and store air- and moisture-sensitive compounds
under an atmosphere of dried and deoxygenated N2. All gases were
supplied by BOC Gases UK. All glassware was dried in an oven at 160
°C, cooled under 10−3 mbar vacuum, and then purged with N2.
Organic solvents were collected from the Vacuum Atmospheres
solvent tower drying system, where they had been passed over a
column of molecular sieves for 24 h prior to collection; they were then
degassed prior to use and subsequent storage over 4 Å molecular
sieves. The solvents d8-THF and C6D6 were dried over K metal,
distilled under reduced pressure, and degassed prior to storage under
N2. All solvents were supplied by Sigma-Aldrich or Fisher Scientific.
NMR spectra were recorded on Bruker AVA400, AVA500, and
PRO500 spectrometers. 1H and 13C{1H} NMR chemical shifts are
referenced to residual solvent resonances calibrated against an external
standard (SiMe4, δ 0 ppm). 19F{1H} NMR chemical shifts are
referenced to an external standard (CCl3F, δ 0 ppm). X-ray
crystallographic data were collected at 170 K on an Oxford Diffraction
Excalibur diffractometer using graphite-monochromated Mo Kα
radiation equipped with an Eos CCD detector (λ = 0.71073 Å).
MALDI-TOF mass spectra were measured on a Bruker UltrafleXtreme
spectrometer and are calibrated against red phosphorus. Elemental
analyses were conducted by Mr. Stephen Boyer at the London
Metropolitan University. H4La and H4Lb were prepared according to
published procedures, and 1 M ZnEt2 in hexanes and Zn{N(SiMe3)2}2
were used as supplied (Sigma-Aldrich). DFT calculations were
conducted using the Gaussian09 package at the University of
Edinburgh.
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−144.68 (d, 4F, JFF = 22.4 Hz, ArF o-F, overlap with minor isomer),
3
3
−160.25 (t, 2F, JFF = 21.8 Hz, ArF p-F), −165.31 (t of d, 4F, JFF
=
30.5 Hz, ArF m-F). Data for the minor isomer are as follows. 19F{1H}
NMR (d8-THF, 300 K): δF/ppm −144.68 (d, 4F, 3JFF = 22 Hz, ArF o-
F), −161.27 (t, 2F, JFF = 22 Hz, ArF p-F), −165.76 (broad t, 4F, ArF
3
m-F). Anal. Calcd for C62H30F10N8Zn2 (Mr = 1207.76): C, 61.66; H,
2.50; N, 9.28. Found: C, 61.45; H, 2.35; N, 9.16.
Synthesis of 2a. A brown solution of H4La (0.10 g, 0.1 mmol) in
THF (10 cm3) was treated with a solution of ZnEt2 in hexanes (0.5
cm3, 1 mol dm−3, 0.5 mmol) at −80 °C; the solution turned dark
yellow. The mixture was warmed to room temperature and stirred for
18 h, after which the solvent was removed under vacuum, giving a dark
yellow solid that was dried under vacuum at 70 °C. Yield: 0.12 g
(94%). 1H NMR (C6D6, 300 K): δH/ppm 7.68 (s, 4H, imine), 6.75 (d,
3
4H, JHH = 3.2 Hz, pyrrole β-H), 6.55 (s, 4H, Ar C−H), 6.26 (d, 4H,
3JHH = 1.9 Hz, pyrrole β-H), 6.03 (s, 2H, meso-H), 1.99 (s, 12H, Ar-
CH3), 1.32 (t, 12H, 3JHH = 8.1 Hz, ethyl-CH3), 0.42 (q, 8H, 3JHH = 7.9
Hz, ethyl-CH2). 13C{1H} NMR (C6D6, 300 K): δC/ppm 156.71
(imine), 149.64 (pyrrole α-C), 149.03 (ArF, next to meso-C), 145.9 (d,
1JCF = 248 Hz, ArF o-C), 140.6 (d, 1JCF = 251 Hz, ArF p-C), 139.44 (Ar,
next to imine-N), 138.2 (d, 1JCF = 250 Hz, ArF m-C), 137.79 (pyrrole
α-C), 134.78 (Ar, next to CH3), 124.38 (Ar C−H), 122.04 (pyrrole β-
C, nearest to imine), 114.27 (pyrrole β-C, nearest to meso-C), 40.10
(meso-C), 19.20 (Ar-CH3), 12.59 (ethyl-CH3), 0.07 (ethyl-CH2).
19F{1H} NMR (C6D6, 333 K): δF/ppm −140.24 (broad s, 3F, ArF o-
3
3
F), −156.94 (t, 2F, JFF = 21.9 Hz, ArF p-F), −162.26 (t of d, JFF
=
23.0, 8.1 Hz, ArF m-F). Anal. Calcd for C58H50F10N8Zn4 (Mr =
1310.7): C, 53.15; H, 3.85; N, 8.55. Found: C, 52.87; H, 3.71; N, 8.46.
Synthesis of 2b. This compound was prepared as described for 2a.
To a solution of H4Lb (0.20 g, 0.18 mmol) in THF (30 cm3) was
added a solution of ZnEt2 in hexanes (0.75 cm3, 1 mol dm−3, 0.75
Synthesis of 1a. To a brown solution of H4La (0.41 g, 0.45 mmol)
in THF (20 cm3) was added a solution of Zn{N(SiMe3)2}2 (0.36 cm3,
0.90 mmol) in THF (ca. 2 cm3) at room temperature. The mixture
was stirred for 24 h, after which the solvent was removed under
vacuum, yielding a brown solid that was dried under vacuum at 70 °C.
1
mmol). Yield: 0.128 g (49%). H NMR (d8-THF, 300 K): δH/ppm
8.89 (s, 2H, 9-anth), 8.55 (s, 2H, 10-anth), 8.40 (s, 4H, imine), 7.84
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3
(d, 4H, JHH = 7.0 Hz, 2,7-anth), 7.44 (dd, 4H, JHH = 5.0 Hz, 3,6-
1
anth), 7.14 (d, 4H, 3JHH = 5.1 Hz, 4,5-anth), 6.75 (s, 4H, pyrrole β-H),
Yield: 0.43 g (91%). H NMR (C6D6, 300 K): δH/ppm 7.79 (s, 4H,
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6.54 (s, 4H, pyrrole β-H), 5.81 (s, 2H, meso-H), 0.99 (t, 12H, JHH
=
imine), 6.99 (s, 2H, meso-H), 6.80 (d, 4H, 3JHH = 5 Hz, pyrrole β-H),
3
3
7.5 Hz, ethyl-CH3), 0.10 (q, 8H, JHH = 7.5 Hz, ethyl-CH2). 13C{1H}
6.73 (s, 4H, Ar-H), 6.42 (d, 4H, JHH = 5 Hz, pyrrole β-H), 2.00 (s,
12H, Ar-CH3). 13C{1H} NMR (C6D6, 300 K): δC/ppm 150.47
NMR (d8-THF, 300 K): δC/ppm 158.43 (imine), 148.37 (1,8-anth),
1
146.87 (anth, quaternary-C), 145.3 (d, JCF = 246 Hz, ArF), 139.7 (d,
(pyrrole α-C, next to meso-position), 146.83 (imine), 146.40 (d, 1JCF
246 Hz, ArF o-C), 140.00 (pyrrole α-C, next to imine), 137.9 (d, 1JCF
=
=
1JCF = 256 Hz, ArF), 137.6 (d, 1JCF = 255 Hz, ArF), 136.80 (pyrrole α-
C), 133.12 (pyrrole α-C), 128.05 (10-anth), 127.21 (ArF, next to meso-
C), 126.27 (3,6-anth), 125.44 (2,7-anth), 124.64 (anth, quaternary-C),
120.75 (pyrrole β-C), 118.17 (9-anth), 117.20 (4,5-anth), 114.02
(pyrrole β-C), 40.97 (meso-C), 12.11 (ethyl-CH3), −3.21 (ethyl-CH2).
19F{1H} NMR (d8-THF, 333 K): δF/ppm −140.27 (broad s, 2F, ArF o-
242 Hz, overlapping ArF m- and p-C), 136.79 (Ar, next to imine-N),
134.22 (ArF, next to meso-C), 133.76 (Ar, next to CH3), 119.71
(pyrrole β-C), 116.30 (Ar C−H), 114.87 (pyrrole β-C), 42.15 (meso-
C), 19.74 (Ar-CH3). 19F{1H} NMR (C6D6, 300 K): δF/ppm −139.9
(d, 4F, 3JFF = 20 Hz, ArF o-F), −158.16 (t, 2F, 3JFF = 20 Hz, ArF p-F),
F), −161.21 (t, 2F, 3JFF = 20 Hz, ArF p-F), −164.93 (broad t, 4F, 3JFF
=
3
−163.75 (t, 4F, JFF = 20 Hz, ArF m-F). MALDI-TOF-MS (DCTB):
18 Hz, ArF m-F). Anal. Calcd for C70H50F10N8Zn4 (Mr = 1454.82): C,
57.79; H, 3.46; N, 7.70. Found: C, 57.68; H, 3.52; N, 7.62.
m/z 1063, [C50H30F10N8Zn2, M+ + H]. Anal. Calcd for
C50H30F10N8Zn2 (Mr = 1063.6): C, 56.46; H, 2.84; N, 10.54.
Found: C, 56.28; H, 2.95; N, 10.42.
Synthesis of 3. 2a (10 mg, 8 μmol) was dissolved in a solution of
H2O in C6D6 (concentration of H2O 8.6 mM by 1H NMR integration,
Synthesis of 1b. This compound was prepared as described for 1a.
To a solution of H4Lb (0.50 g, 0.46 mmol) in THF (50 cm3) was
added Zn{N(SiMe3)2}2 (0.391 g, 1.0 mmol). The crude product was
washed with pentane (3 × 2 cm3) and dried at 60 °C. Yield: 0.398 g
(71.2%). Data for the major isomer are as follows. 1H NMR (d8-THF,
300 K): δH/ppm 8.66 (s, 2H, 9-anth), 8.21 (s, 4H, imine), 7.84 (s, 2H,
10-anth), 7.29 (d, 4H, 3JHH = 8.4 Hz, 2,7-anth), 6.84 (t, 4H, 3JHH = 10
Hz, 3,6-anth, overlap with minor isomer), 6.78 (d, 4H, 3JHH = 6.3 Hz,
1
0.9 cm3, 8 μmol of H2O). Yield: 5 mg (50% conversion by H NMR
1
integration). H NMR (C6D6): δH/ppm 7.95 (s, 4H, imine), 6.90 (d,
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4H, JHH = 5 Hz, pyrrole β-H), 6.58 (s, 4H, Ar C−H), 6.43 (s, 2H,
meso-H), 6.22 (broad s, 4H, pyrrole β-H), 2.05 (s, 12H, Ar-CH3), 1.51
3
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(t, 6H, JHH = 10 Hz, ethyl-CH3), 0.30 (q, 4H, JHH = 10 Hz, ethyl-
CH2). 13C{1H} NMR (d8-THF, 300 K): δC/ppm 153.59 (imine),
148.90 (ArF, next to meso-C), 147.1 (d, JCF = 246 Hz, ArF), 142.56
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Organometallics XXXX, XXX, XXX−XXX