Dinuclear Complexes Assembled from Asymmetric CoIII Bis(dioximates) and Boronic Acids
FULL PAPER
3
1 H, para py), 8.77 (d, JH,H = 6.2 Hz, 2 H, ortho py), 18.20 (s, 2 (400 MHz, CDCl3, TMS): δ = 1.28 (s, 6 H, axial CH3), 2.53 (s, 12
3
H, OHO) ppm. cis-[CH3Co(mpgH)2py] (2): Yield: 0.124 g (27%).
C24H26CoN5O4 (507.43): calcd. C 56.8, H, 5.16, N 13.8; found C
56.7, H 5.40, N 14.0. ESI-MS (60 V, MeOH): m/z calcd. for cis-
[CH3Co(mpgH)2py] 507.428; found 508.0 (24%); further peaks: m/
z (%) = 529.9 (28) [M + Na+] , 429.1 (80) [M – py], 451.0 (100) [M
+ Na+ – py]. 1H NMR (400 MHz, CDCl3, TMS): δ = 1.12 (s, 3 H,
axial CH3), 2.08 (s, 6 H, equatorial CH3), 7.25–7.42 (m, 12 H, meta
H, CH3C=NOB), 3.37 (s, 6 H, OCH3), 6.84 (d, JH,H = 6.3 Hz, 4
H, meta of py), 7.16 (d, JH,H = 6.3 Hz, 4 H, ortho of py), 7.45–
7.55 (m, 20 H, equatorial phenyls), 17.94 (s, 2 H, OHO) ppm.
3
Structure Determinations: Single crystals suitable for X-ray data
collection were obtained as reported above. Data for the crystals
of compounds 1 and 4, being of small size and, in the case of 4,
also of poor quality, were collected at 200 K and 293 K, respec-
tively, using a rotating copper-anode generator working at 45 kV
and 95 mA, equipped with an Enraf Nonius KCCD diffractometer;
88 images for 1 and 176 for 4 were collected (crystal-to-detector
distance of 42 mm) with 6° oscillation and 20 s/° exposure time for
CCD image. The data were processed, scaled, and merged with the
programs DENZO and SCALE-PACK.[22] Data for the crystals of
compounds 2 and 3 were collected at 293 K and 150 K, respec-
tively, with a Nonius DIP 1030 H System, using graphite-mono-
chromated Mo-Kα radiation. For both compounds a total of 30
frames were collected using the Xpress program[23] over half of re-
ciprocal space, with a rotation of 6° about the axis. A Mac Science
Image Plate (diameter = 300 mm) was used and the crystal-to-plate
distance was fixed at 90 mm. The determination of unit-cell para-
meters, integration of reflection intensities, and data scaling were
performed using the programs DENZO and SCALE-PACK. All
structures were solved by direct methods,[24] followed by Fourier
syntheses and refined by full-matrix least squares (on F2) cycles.[25]
The H atoms were not refined but were included at calculated posi-
tions in the final refinements. A suite of programs[26] was also used
for the geometrical and final calculations. Crystal and refinement
data are given in Table 3. CCDC-264667 to -264670 (1–4, respec-
tively) contain the supplementary crystallographic data for this pa-
per. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
3
of py and equatorial phenyls), 7.79 (t, JH,H = 7.6 Hz, 1 H, para of
py), 8.75 (d, 3JH,H = 6.2 Hz, 2 H, ortho of py), 18.39 (s, 1 H, OHO),
18.56 (s, 1 H, OHO) ppm.
Synthesis of 3: A solution of 3-pyridylboronic acid (12 mg,
0.098 mmol in 6 mL of MeOH) was added to a solution of trans-
[CH3Co(mpgH)2py] (0.050 g, 0.098 mmol in 1 mL CHCl3) The pH
was adjusted to 5.5 with concentrated HClO4 and NaOH. The
solution was filtered and set aside in a beaker covered with Paraf-
ilm. After some days, small orange crystals of 3, suitable for X-ray
analysis, appeared and were collected by filtration. Yield: 33.2 mg
(62%). C50H54B2Co2N10O10 (1094.5): calcd. C 54.8, H 4.97, N 12.8;
found C 55.3, H 5.10, N 12.7. ESI-MS (90 V, CH2Cl2/HCOOH
1%): m/z calcd. for 3 1094.5; found 1095.4 (100%). 1H NMR
(400 MHz, CDCl3, TMS: δ = 1.45 (s, 6 H, axial CH3), 1.79 (s, 6
H, CH3C=NOH), 2.01 (s, 6 H, CH3C=NOB), 3.31 (s, 6 H, OCH3),
7.12–7.74 (m, 22 H, meta of py and equatorial phenyls), 7.90 (d,
3
3JH,H = 6.8 Hz, 2 H, ortho of py), 8.30 (d, JH,H = 5.4 Hz, 2 H,
para of py), 9.60 (s, 2 H, ortho of py), 18.54 (s, 2 H, OHO) ppm.
Synthesis of 4: The synthesis was performed as described above
using 4-pyridylboronic acid instead of 3-pyridylboronic acid. Yield:
17 mg (32%). C50H54B2Co2N10O10 (1094.5): calcd. C 54.8, H 4.97,
N 12.8; found C 54.3, H 5.03, N 12.3. ESI-MS (90 V, CH2Cl2/
HCOOH 1%): m/z calcd. for 4 1094.5; found 1095.4 (100%). 1H
NMR (400 MHz, CDCl3, TMS): δ = 1.28 (s, 6 H, axial CH3), 2.27
(s, 6 H, CH3C=NOH), 2.51 (s, 6 H, CH3C=NOB), 3.22 (s, 6 H,
Supporting Information: Time-resolved 1H NMR spectra relative to
the formation and decomposition of 3, 1H NMR spectra of 1–6,
and ESI mass spectra of 3–6.
3
3
OCH3), 6.72(d, JH,H = 5.4 Hz, 2 H, meta of py), 6.83(d, JH,H
=
3
5.4 Hz, 2 H, meta of py), 7.05 (d, JH,H = 5.4 Hz, 2 H, ortho of
py), 7.09 (d, 3JH,H = 5.4 Hz, 2 H, ortho of py), 7.45–7.65 (m, 20 H,
phenyls), 17.89 (s, 2 H, OHO) ppm.
Synthesis of 5: A solution of 3-pyridylboronic acid (12 mg,
0.098 mmol in 6 mL of MeOH) was added to a solution of cis-
[CH3Co(mpgH)2py] (0.050 g, 0.098 mmol in 1 mL of CHCl3) and
the pH was adjusted to 5.5. The solution was filtered and allowed
to stand in a beaker covered with Parafilm for2 d. Then, the solvent
was evaporated under atmospheric pressure and the orange solid
collected by filtration. Yield: 22.3 mg (41%). C50H54B2Co2N10O10
(1094.5): calcd. C 54.8, H 4.97, N 12.8; found C 53.0, H 4.50, N
11.8. ESI-MS (90 V, CH2Cl2/HCOOH 1%): m/z calcd. for 5 1094.5;
Acknowledgments
This work was supported by MIUR (Prin 2003 no. 2003037580).
P. S. acknowledges CIRCMSB (Consorzio Interuniversitario per la
Ricerca sui Metalli nei Sistemi Biologici) for a grant. We thank Dr.
Fabio Hollan for recording the mass spectra.
[1] a) N. Bresciani Pahor, M. Forcolin, L. G. Marzilli, L. Randac-
cio, M. F. Summers, P. J. Toscano, Coord. Chem. Rev. 1985, 63,
1; b) L. Randaccio, N. Bresciani Pahor, E. Zangrando, L. G.
Marzilli, Chem. Soc. Rev. 1989, 18, 225; c) L. Randaccio, Com-
ments Inorg. Chem. 1999, 21, 327.
1
found 1095.2 (100%). H NMR (400 MHz, CDCl3, TMS: δ = 1.49
(s, 6 H, axial CH3), 1.99 (s, 12 H, CH3C=NOB), 3.44 (s, 6 H,
OCH3), 7.30–7.50 (m, 22 H, meta of py and equatorial phenyls),
3
3
[2] A. A. Gridner, S. D. Ittel, Chem. Rev. 2001, 101, 3611 and ref-
8.09 (d, JH,H = 7.1 Hz, 2 H, ortho of py), 8.46 (d, JH,H = 5.5 Hz,
2 H, para of py), 9.72 (s, 2 H, ortho of py), 18.56 (s, 2 H, OHO)
ppm.
erences cited therein.
[3] M. E. Welker, Curr. Org. Chem. 2001, 5, 785 and references
cited therein.
Synthesis of 6: A solution of 4-pyridylboronic acid (12 mg,
0.098 mmol in 6 mL of MeOH) was added to a solution of cis-
[CH3Co(mpgH)2py] (0.050 g, 0.098 mmol in 1 mL of CHCl3) and
the pH was adjusted to 5.5. The solution was filtered and allowed
to stand in a beaker covered with Parafilm for 2 d. Then, two drops
of water were added and the solvent evaporated under atmospheric
pressure. The orange solid was collected by filtration. Yield: 6.3 mg
(12%). C50H54B2Co2N10O10 (1094.5): calcd. C 54.8, H 4.97, N 12.8;
found C 53.8, H 5.41, N 11.7. ESI-MS (90 V, CH2Cl2/HCOOH
1%): m/z calcd. for 6 1094.5; found 1095.4 (80%). 1H NMR
[4] B. D. Gupta, R. Yamuna, V. Singh, U. Tiwari, Organometallics
2003, 22, 226 and references cited therein.
[5] B. D. Gupta, K. Qanungo, R. Yamuna, A. Pandey, U. Tiwari,
V. Vijaikanth, V. Singh, T. Barclay, W. Cordes, J. Organomet.
Chem. 2000, 608, 106 and references cited therein.
[6] a) P. J. Toscano, L. Lettko, E. Schermerhorn, J. Waechter, K.
Schufon, S. Liu, E. V. Dikarev, J. Zubieta, Polyhedron 2003, 22,
2809; b) C. López, S. Alvarez, M. Font Bardía, X. Solans, J.
Organomet. Chem. 1991, 414, 245; c) C. López, S. Alvarez, M.
Aguiló, X. Solans, M. Font-Altaba, Inorg. Chim. Acta 1987,
127, 153; d) C. López, S. Alvarez, X. Solans, M. Font-Altaba,
Eur. J. Inorg. Chem. 2005, 3936–3944
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3943