Ring-functionalized niobocene complexes
fulvene (6; 0.59 g, 2.76 mmol) and Super-Hydride (2.85 ml, 2.85
mmol). Yield 0.48 g (0.81 mmol, 59%); brown powder. Anal. Calcd
for C28H30Cl2NbO4: C 56.58; H: 5.09. Found: C 56.52; H 5.01. EPR
(CH2Cl2): giso = 1.981, |Aiso| = 113.6 G. Single crystals of 17 suitable
for X-ray analysis were obtained by careful layering of the CH2Cl2 so-
lution with a double volume of hexane.
multiplate reader (Tecan Infinite 200). Compounds 12–22 were
dissolved in DMSO and diluted by cultivation medium to desired
concentrations. The MOLT-4 cells were seeded in a 96-well plate,
incubated in solutions of compounds 12–22 for 24 h, then
washed in pure media and incubated for 180 min in WST-1 solu-
tion. The same cells incubated in the cultivation media only were
used as the control.
Preparation of {3,4-(MeO)2C6H3CH2C5H4}2NbCl2 (18)
The steps of synthesis followed the procedure for compound 14.
Reagents: NbCl4(THF)2 (0.63 g, 1.66 mmol), 6-(3′,4′-dimetho-
xyphenyl)fulvene (7; 0.76 g, 3.55 mmol) and Super-Hydride
(3.50 ml, 3.50 mmol). Yield 0.52 g (0.88 mmol, 53%); brown
powder. Anal. Calcd for C28H30Cl2NbO4: C 56.58; H: 5.09. Found:
C 56.32; H: 4.92. EPR(CH2Cl2): giso = 1.982, |Aiso| = 113.9 G.
Crystallography
The X-ray data for crystals of 12, 14 and 17 were obtained at 150 K
using an Oxford Cryostream low-temperature device on a Nonius
KappaCCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å), a
graphite monochromator, and the ϕ and χ scan mode. Data re-
ductions were performed with DENZO-SMN.[39] Absorption was
corrected by integration methods.[40] Structures were solved by
direct methods (SIR92)[41] and refined by full-matrix least squares
based on F2 (SHELXL97).[42] Hydrogen atoms were mostly local-
ized on a difference Fourier map; however, to ensure uniformity
of treatment of crystal, all hydrogens were recalculated into ideal-
ized positions (riding model) and assigned temperature factors
Preparation of {2,4,6-(MeO)3C6H2CH2C5H4}2NbCl2 (19)
The steps of synthesis followed the procedure for compound 14.
Reagents: NbCl4(THF)2 (0.76 g, 2.01 mmol), 6-(2′,4′,6′-trimetho-
xyphenyl)fulvene (8; 0.98 g, 4.02 mmol) and Super-Hydride
(4.00 ml, 4.00 mmol). Yield 0.64 g (0.98 mmol, 49%); brown
powder. Anal. Calcd for C30H34Cl2NbO6: C: 55.06; H: 5.24. Found:
C: 55.14; H: 5.33. EPR(CH2Cl2): giso = 1.981, |Aiso| = 113.9 G.
H
iso(H) = 1.2 Ueq (pivot atom) or 1.5 Ueq (methyl). The absolute
Preparation of {3,4,5-(MeO)3C6H2CH2C5H4}2NbCl2 (20)
structure of 12 was determined according to standard Flack pro-
cedures.[43] Crystallographic data are summarized in Table 4.
Figs. 2–4 were drawn using PLATON.[44]
The steps of synthesis followed the procedure for compound 14.
Reagents: NbCl4(THF)2 (0.65 g, 1.72 mmol), 6-(3′,4′,5′-trimetho-
xyphenyl)fulvene (9; 0.84 g, 3.44 mmol) and Super-Hydride
(3.43 ml, 3.43 mmol). Yield 0.58 g (0.89 mmol, 52%); brown
powder. Anal. Calcd for C30H34Cl2NbO6: C 55.06; H 5.24. Found:
C 54.88; H 5.42. EPR(CH2Cl2): giso = 1.981, |Aiso| = 113.8 G.
Acknowledgment
This work was supported by the Ministry of Education of the
Czech Republic (Project No. SG320001).
Preparation of (4-FC6H4CH2C5H4)2NbCl2 (21)
The steps of synthesis followed the procedure for compound 14.
Reagents: NbCl4(THF)2 (0.56 g, 1.40 mmol), 6-(4′-fluorophenyl)
fulvene (10; 0.53 g, 3.08 mmol) and Super-Hydride (3.10 ml,
3.10 mmol). Yield 0.47 g (0.92 mmol, 66%); brown powder. Anal.
Calcd for C24H20Cl2F2Nb: C 56.50; H 3.95. Found: C 56.62; H 4.03.
EPR(CH2Cl2): giso = 1.981, |Aiso| = 114.5 G.
References
[1] H. Köpf, P. Köpf-Maier, Angew. Chem. Int. Edit. 1979, 18, 477–478.
[2] P. Köpf-Maier, H. Köpf, Struct. Bonding 1988, 103–194.
[3] P. M. Abeysinghe, M. M. Harding, Dalton Trans. 2007, 3474–3482.
[4] K. Strohfeldt, M. Tacke, Chem. Soc. Rev. 2008, 37, 1174–1187.
[5] C. C. L. Pereira, M. Nolasco, S. S. Braga, F. A. A. Paz, P. Ribeiro-Claro, M.
Pillinger, I. S. Gonçalves, Organometallics 2007, 26, 4220–4228.
[6] I. Turel, A. Demsar, J. Kosmrlj, J. Incl. Phenom. Macrocycl. Chem. 1999,
35, 595–604.
Preparation of (4-Me2NC6H4CH2C5H4)2NbCl2 (22)
The steps of synthesis followed the procedure for compound 14.
Reagents: NbCl4(THF)2 (0.59 g, 1.56 mmol), 6-(4′-dimethyl-
aminophenyl)fulvene (11; 0.62 g, 3.16 mmol) and Super-Hydride
(3.20 ml, 3.20 mmol). Yield: 0.50 g (0.90 mmol, 58%). Brown pow-
der. Anal. Calcd for C28H32Cl2N2Nb: C 60.01; H: 5.76; N 5.00. Found:
C 60.12; H 5.53; N 5.06. EPR(CH2Cl2): giso = 1.980, |Aiso| = 114.1 G.
[7] J. Vinklárek, J. Honzíček, J. Holubová, Cent. Eur. J. Chem. 2005, 3,
72–81.
[8] S. S. Braga, I. S. Gonçalves, M. Pillinger, P. Ribeiro-Claro, J. J. C.
Teixeira-Dias, J. Organomet. Chem. 2001, 632, 11–16.
[9] P. Köpf-Maier, H. Köpf, Chem. Rev. 1987, 87, 1137–1152.
[10] J. Vinklárek, H. Paláčková, J. Honzíček, Collect. Czech. Chem. Commun.
2004, 69, 811–821.
[11] P. Köpf-Maier, I. C. Tornieporth-Oetting, Biometals 1996, 9, 267–271.
[12] J. Vinklárek, H. Paláčková, J. Honzíček, J. Holubová, M. Holčapek, I.
Císařová, Inorg. Chem. 2006, 45, 2156–2162.
Cytotoxicity Studies
[13] J. Vinklárek, H. Hurychová, J. Honzíček, L. Šebestová, Z. Padělková,
M. Řezáčová, Eur. J. Inorg. Chem. 2013, 2665–2672.
[14] O. R. Allen, A. L. Gott, J. A. Hartley, J. M. Hartley, R. J. Knox, P. C. McGowan,
Dalton Trans. 2007, 5082–5090.
Studies were performed on human T-lymphocytic leukemia cells
MOLT-4 obtained from the American Type Culture Collection
(USA). The cells were cultured in Iscove’s modified Dulbecco’s
medium supplemented with a 20% fetal calf serum and 0.05%
L-glutamine (all Sigma-Aldrich, USA) in a humidified incubator at
37°C and a controlled 5% CO2 atmosphere. The cell lines in the
maximal range of up to 20 passages have been used for this study.
Cytotoxicity of compounds 12–22 was evaluated by the WST-1
cell viability test (Roche, Germany) according to manufacturer’s
instructions. The assay is based on the reduction of WST-1 (4-[3-
(4-Iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene
disulfonate) by viable cells. The reaction produces a colored solu-
ble formazan salt. Absorbance at 440 nm was measured using a
[15] J. R. Boyles, M. C. Baird, B. G. Campling, N. Jain, J. Inorg. Biochem.
2001, 84, 159–162.
[16] I. Klepalová, J. Honzíček, J. Vinklárek, Z. Padělková, L. Šebestová,
M. Řezáčová, Inorg. Chim. Acta 2013, 402, 109–115.
[17] J. Ceballos-Torres, S. Gómez-Ruiz, G. N. Kaluđerović, M. Fajardo,
R. Paschke, S. Prashar, J. Organomet. Chem. 2012, 700, 188–193.
[18] W. Cini, T. D. Bradshaw, W. Lewis, S. Woodward, Eur. J. Org. Chem.
2013, 3997–4007.
[19] O. R. Allen, L. Croll, A. L. Gott, R. J. Knox, P. C. McGowan, Organome-
tallics 2004, 23, 288–292.
[20] N. J. Sweeney, O. Mendoza, H. Müller-Bunz, C. Pampillón, F.-J. K. Rehmann,
K. Strohfeldt, M. Tacke, J. Organomet. Chem. 2005, 690, 4537–4544.
Appl. Organometal. Chem. 2014, 28, 252–258
Copyright © 2014 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc