University of Groningen Neutral and cationic alkyl and alkynyl complexes of lanthanum Tazelaar, CGJ; Bambirra, S; van Leusen, D; Meetsma, A; Hessen, B; Teuben, JH; Tazelaar, Cornelis G.J. Published in: Organometallics DOI: 10.1021/om034403u IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2004 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Tazelaar, C. G. J., Bambirra, S., van Leusen, D., Meetsma, A., Hessen, B., Teuben, J. H., & Tazelaar, C. G. J. (2004). Neutral and cationic alkyl and alkynyl complexes of lanthanum: Synthesis, stability, and cis- selective linear alkyne dimerization. Organometallics, 23(5), 936-939. DOI: 10.1021/om034403u Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 10-02-2018
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University of Groningen Neutral and cationic alkyl and ... · By: Cornelis G. J. Tazelaar, Sergio Bambirra, Daan van Leusen, , Auke Meetsma, Bart Hessen* and Jan H. Teuben Part I:
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University of Groningen
Neutral and cationic alkyl and alkynyl complexes of lanthanumTazelaar, CGJ; Bambirra, S; van Leusen, D; Meetsma, A; Hessen, B; Teuben, JH; Tazelaar,Cornelis G.J.Published in:Organometallics
DOI:10.1021/om034403u
IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.
Document VersionPublisher's PDF, also known as Version of record
Publication date:2004
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):Tazelaar, C. G. J., Bambirra, S., van Leusen, D., Meetsma, A., Hessen, B., Teuben, J. H., & Tazelaar, C.G. J. (2004). Neutral and cationic alkyl and alkynyl complexes of lanthanum: Synthesis, stability, and cis-selective linear alkyne dimerization. Organometallics, 23(5), 936-939. DOI: 10.1021/om034403u
CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).
Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.
Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.
Me2TACN(CH2)2NHtBu4, Me3SiCH2Li5, LaBr3(THF)46 were prepared according to
1 Fassbeck, C.; Wieghardt, K. Z. Anorg. Allg. Chem., 1992, 608, 60. 2 Fletcher, J. S.; Male, N. A. H.; Wilson, P. J.; Rees, L. H.; Mountford, P.; Schröder, M. J. Chem. Soc., Dalton Trans., 2000, 4130 3 Wannagat, U.; Schreiner, G. Monath. Chem. 1965, 96, 1889 4 Bambirra, S.; Van Leusen, D.; Meetsma, A.; Hessen, B; Teuben, J. H. Chem. Commun., 2001, 637. 5 Lewis, H. L.; Brown, T. L. J. Am. Chem. Soc. 1970, 92, 4664
published procedures. Phenylacetylene (Aldrich) was dried over molecular sieves
(Aldrich 4Å) under nitrogen atmosphere before use. NMR spectra were recorded on
Varian Gemini VXR 300 or Varian Inova 500 spectrometers in NMR tubes equipped
with Teflon Young valve. The 1H NMR spectra were referenced to resonances of
residual protons in deuterated solvents. The 13C NMR spectra were referenced to
carbon resonances of deuterated solvents and reported in ppm relative to TMS (δ 0
ppm). GC analyses were performed on a HP 6890 instrument equipped with a HP-1
dimethylpolysiloxane column (19095 Z-123). GC/MS analyses were conducted using
a HP 5973 mass-selective detector attached to a HP 6890 GC instrument. Elemental
analyses were performed at the Microanalytical Department of the Univeristy of
Groningen. Given values are the average of at least two independent determinations.
In initial combustion analysis experiments, the compounds containing La and Si (and
especially compound 2) gave carbon contents that were significantly and consistently
too low, whereas the other elements (H, N) gave values close to those expected. This
may be associated with the formation of inert metal carbides during combustion. To
counteract this, aliquots of V2O5 were added to the solid samples before combustion.
This resulted in a relative increase of the determined amounts of C (albeit still below
the calculated values); the values of these runs are given. IR spectra were recorded on
a Mattson 4020 Galaxy FT-IR spectrometer.
6 LaBr3: Taylor, M. D.; Carter, C. P. J. Inorg. Nucl. Chem. 1962, 24, 387. LaBr3(THF)4: Herzog, S.; Gustav, K.; Krüger, E.; Oberender, H.; Schuster, R. Z. Chem. 1963, 3, 428.
Synthesis of [Me2-TACN-SiMe2NHBut] (HB)
To a solution of 2.20 g (13.49 mmol) of Li[Me2-TACN] in hexane (50 ml) was
added 2.34 g (13.50 mmol) of ClSiMe2NHBut. The mixture was stirred for one hour,
after which the precipitated LiCl was filtered off. The hexane was removed from the
filtrate under reduced pressure to leave the title compound as a light yellow oil. Yield:
3.70 g (12.9 mmol, 96 %). The identity of the product was established by NMR
spectroscopy (purity > 95%) and the product was used without further purification.
In one experiment a solution of 50 µL (0.45 mmol) of phenyl acetylene in 0.4 mL of
bromobenzene-d5 was added to a solid mixture of 1 and [PhNMe2H][B(C6F5)4] (10
µmol each; substrate/catalyst ratio 45:1). The reaction mixture was transferred to an
NMR tube and warmed to 50oC. The reaction was monitored by 1H NMR, showing
full conversion in 15 min. The reaction mixture was quenched by the addition of 25
µL of methanol and the products were analyzed by GC and GC-MS. The dimer
fraction contained 99% of cis-enyne and 1% of trans-enyne. Approximately 1% of
trimer (based on the initial amount of phenylacetylene; 3 isomers) was also observed.
The same procedure, but now using 500 µL (0.45 mmol) of phenylacetylene in 0.4
mL of bromobenzene-d5 (substrate/catalyst ratio 450:1), led to full conversion in 240
min. The relatively low observed conversion rate in this experiment may be due to the
reduced polarity of the reaction medium. Analysis of the mixture as described above
showed that the dimer fraction contained 99% of cis-enyne and 1% of trans-enyne. A
trace amount of trimer was also observed.
Part II: Structure determination of [Me 2-TACN-(CH 2) 2NBut]La(CH 2SiMe 3) 2 (1)
Experimental
X-ray diffraction: Crystal and Molecular Structure.
Suitable colorless colored block-shaped crystals were obtained by recrystallisation
from toluene. A crystal with the dimensions of 0.210 x 0.190 x 0.110 mm was
mounted on top of a glass fiber, by using inert-atmosphere handling techniques, and
aligned on a Bruker1 SMART APEX CCD diffractometer (Platform with full three-
circle goniometer). The diffractometer was equipped with a 4K CCD detector set 60.0
mm from the crystal. The crystal was cooled to 100(1) K using the Bruker
KRYOFLEX low-temperature device. Intensity measurements were performed using
graphite monochromated Mo-Kα radiation from a sealed ceramic diffraction tube
(SIEMENS). Generator settings were 50 KV/ 40 mA. SMART was used for
preliminary determination of the unit cell constants and data collection control. The
intensities of reflections of a hemisphere were collected by a combination of 3 sets of
exposures (frames). Each set had a different φ angle for the crystal and each exposure
covered a range of 0.3° in ω. A total of 1800 frames were collected with an exposure
time of 10.0 seconds per frame. The overall data collection time was 8.0 h. Data
integration and global cell refinement was performed with the program SAINT. The
final unit cell was obtained from the xyz centroids of 8942 reflections after
integration. Intensity data were corrected for Lorentz and polarization effects, scale
variation, for decay and absorption: a multi-scan absorption correction was applied,
based on the intensities of symmetry-related reflections measured at different angular
settings (SADABS)2, and reduced to Fo2. The program suite SHELXTL was used for
space group determination (XPREP).1
The unit cell3 was identified as monoclinic; reduced cell calculations did not indicate
any higher metric lattice symmetry.4 The space group P21/n, was derived from the
systematic extinctions. Examination of the final atomic coordinates of the structure
did not yield extra metric symmetry elements.6,7
The structure was solved by Patterson methods and extension of the model was
accomplished by direct methods applied to difference structure factors using the
program DIRDIF.8 The positional and anisotropic displacement parameters for the
non-hydrogen atoms were refined. A subsequent difference Fourier synthesis resulted
in the location of all the hydrogen atoms, which coordinates and isotropic
displacement parameters were refined.
Final refinement on F2 carried out by full-matrix least-squares techniques converged
at wR(F2) = 0.0676 for 6852 reflections and R(F) = 0.0290 for 5628 reflections with
Fo ≥ 4.0 σ(Fo) and 474 parameters. The final difference Fourier map was essentially
featureless: no significant peaks (1.09(9) e/Å3) having chemical meaning above the
general background were observed.
The positional and anisotropic displacement parameters for the non-hydrogen atoms
and isotropic displacement parameters for hydrogen atoms were refined on F2 with
full-matrix least-squares procedures minimizing the function Q = h[w(│(Fo2) -
k(Fc2)│)2], where w = 1/[σ2(Fo
2) + (aP)2 + bP], P = [max(Fo2,0) + 2Fc
2] / 3, F0 and Fc
are the observed and calculated structure factor amplitudes, respectively; ultimately
the suggested a (=0.0282) and b (= 0.1125) were used in the final refinement.
Crystal data and numerical details on data collection and refinement are given in
Table 1. Final fractional atomic coordinates, equivalent displacement parameters and
anisotropic displacement parameters for the non-hydrogen atoms are given in Table 2.
Molecular geometry data are collected in Table 3. Tables of atom positions,
displacement parameters, comprehensive distances and angles and tables of (Fo2),
(Fc2) and σ(Fo
2) are given as supplementary material8 for this paper. Neutral atom
scattering factors and anomalous dispersion corrections were taken from International
Tables for Crystallography.11
All refinement calculations and graphics were performed on a Pentium-III / Debian-
Linux computer at the University of Groningen with the program packages SHELXL12
(least-square refinements), a locally modified version of the program PLUTO13
(preparation of illustrations) and PLATON10 package (checking the final results for
missed symmetry with the MISSYM option, solvent accessible voids with the SOLV
option, calculation of geometric data and the ORTEP10 illustrations).
References. 1. Bruker (2000). SMART, SAINT, SADABS, XPREP and SHELXTL/NT. Area
Detector Control and Integration Software. Smart Apex Software Reference Manuals. Bruker Analytical X-ray Instruments. Inc., Madison, Wisconsin, USA.
2. Sheldrick, G.M. (2001). SADABS. Version 2. Multi-Scan Absorption Correction Program. University of Göttingen, Germany.
3. Duisenberg, A. J. M. (1992). J. Appl. Cryst. 25, 92-96.
4. Spek, A.L. (1988). J. Appl. Cryst. 21, 578-579. 5. Le Page, Y. (1987). J. Appl. Cryst. 20, 264-269. 6. Le Page, Y. (1988). J. Appl. Cryst. 21, 983-984. 7. Beurskens, P.T., Beurskens, G., Gelder, R. de, García-Granda, S., Gould,
R.O., Israël, R. & Smits, J.M.M. (1999). The DIRDIF-99 program system, Crystallography Laboratory, University of Nijmegen, The Netherlands.
8. Hall, S.R, Allen, F.H. & Brown, I.D. (1991). Acta Cryst. A47, 655-685. 9. Spek, A.L. (2002). PLATON. Program for the Automated Analysis of
Molecular Geometry (A Multipurpose Crystallographic Tool). Version of Feb. 2002. University of Utrecht, The Netherlands.
10. International Tables for Crystallography (1992). Vol. C. Edited by A.J.C. Wilson, Kluwer Academic Publishers, Dordrecht. The Netherlands.
11. Sheldrick, G.M. (1997b). SHELXL-97. Program for the Refinement of Crystal Structures. University of Göttingen, Germany.
12. Meetsma, A. (2002). PLUTO. Molecular Graphics Program. University of Groningen, The Netherlands.
13. Bondi, A. (1964). J. Phys. Chem. 68, 441-451. 14. Spek, A.L. (1990). Acta Cryst. A46, C-34. 15. Spek, A.L. (1994). Am. Crystallogr. Assoc. Abstr. 22, 66. 16. International Tables for Crystallography (1983). Vol. A. Space-group
symmetry, edited by T. Hahn. Dordrecht: Reidel. (Present distributor Kluwer Academic Publishers, Dordrecht).
X-ray diffraction: Crystal and Molecular Structure.
Suitable colorless colored block-shaped crystals were obtained by recrystallisation
from toluene. A crystal with the dimensions of 0.39 x 0.31 x 0.16 mm was mounted
on top of a glass fiber, by using inert-atmosphere handling techniques, and aligned on
a Bruker1 SMART APEX CCD diffractometer (Platform with full three-circle
goniometer). The diffractometer was equipped with a 4K CCD detector set 60.0 mm
from the crystal. The crystal was cooled to 100(1) K using the Bruker KRYOFLEX
low-temperature device. Intensity measurements were performed using graphite
monochromated Mo-Kα radiation from a sealed ceramic diffraction tube
(SIEMENS). Generator settings were 50 KV/ 40 mA. SMART was used for
preliminary determination of the unit cell constants and data collection control. The
intensities of reflections of a hemisphere were collected by a combination of 3 sets of
exposures (frames). Each set had a different φ angle for the crystal and each exposure
covered a range of 0.3° in ω. A total of 1800 frames were collected with an exposure
time of 10.0 s per frame. The overall data collection time was 8.0 h. Data integration
and global cell refinement was performed with the program SAINT. The final unit cell
was obtained from the xyz centroids of 8203 reflections after integration. Intensity
data were corrected for Lorentz and polarization effects, scale variation, for decay and
absorption: a multi-scan absorption correction was applied, based on the intensities of
symmetry-related reflections measured at different angular settings (SADABS)2, and
reduced to Fo2. The program suite SHELXTL was used for space group determination
(XPREP).1
The unit cell3 was identified as triclinic, space group P-1: the E-statistics were
indicative of a centrosymmetric space group.4 Reduced cell calculations did not
indicate any higher metric lattice symmetry5 and examination of the final atomic
coordinates of the structure did not yield extra metric symmetry elements.6,7
The structure was solved by Patterson methods and extension of the model was
accomplished by direct methods applied to difference structure factors using the
program DIRDIF.8 The positional and anisotropic displacement parameters for the
non-hydrogen atoms were refined. A subsequent difference Fourier synthesis resulted
in the location of all the hydrogen atoms, which coordinates and isotropic
displacement parameters were refined.
Final refinement on F2 carried out by full-matrix least-squares techniques converged
at wR(F2) = 0.0570 for 13308 reflections and R(F) = 0.0230 for 12090 reflections
with Fo ≥ 4.0 σ(Fo) and 860 parameters. The final difference Fourier map was
essentially featureless: no significant peaks (0.81(8) e/Å3) having chemical meaning
above the general background were observed.
The positional and anisotropic displacement parameters for the non-hydrogen atoms
and isotropic displacement parameters for hydrogen atoms were refined on F2 with
full-matrix least-squares procedures minimizing the function Q = h[w(│(Fo2) -
k(Fc2)│)2], where w = 1/[σ2(Fo
2) + (aP)2 + bP], P = [max(Fo2,0) + 2Fc
2] / 3, F0 and Fc
are the observed and calculated structure factor amplitudes, respectively; ultimately
the suggested a (=0.0284) and b (= 0.9545) were used in the final refinement.
Crystal data and numerical details on data collection and refinement are given in
Table 1. Final fractional atomic coordinates, equivalent displacement parameters and
anisotropic displacement parameters for the non-hydrogen atoms are given in Table 2.
Molecular geometry data are collected in Table 3. Tables of atom positions,
displacement parameters, comprehensive distances and angles and tables of (Fo2),
(Fc2) and σ(Fo
2) are given as supplementary material*7 for this paper. Neutral atom
scattering factors and anomalous dispersion corrections were taken from International
Tables for Crystallography.11
All refinement calculations and graphics were performed on a Pentium-III / Debian-
Linux computer at the University of Groningen with the program packages SHELXL12
(least-square refinements), a locally modified version of the program PLUTO13
(preparation of illustrations) and PLATON10 package (checking the final results for
missed symmetry with the MISSYM option, solvent accessible voids with the SOLV
option, calculation of geometric data and the ORTEP10 illustrations).
*7 Supplementary Material Available: Tables of crystal data, anisotropic displacement parameters, atomic coordinates, bond lengths, bond angles, and torsion angles (as a CIF9 file) and an ORTEP10 plot; a listing of observed and calculated structure factors (also as a CIF file). Supplementary data for this paper are available from the IUCr electronic archives (Reference: CCDCxxxxxxx). Services for accessing these data are described at the back of the journal. (Acta Cryst. C)
References. 1. Bruker (2000). SMART, SAINT, SADABS, XPREP and SHELXTL/NT. Area
Detector Control and Integration Software. Smart Apex Software Reference Manuals. Bruker Analytical X-ray Instruments. Inc., Madison, Wisconsin, USA.
2. Sheldrick, G.M. (2001). SADABS. Version 2. Multi-Scan Absorption Correction Program. University of Göttingen, Germany.
3. Duisenberg, A. J. M. (1992). J. Appl. Cryst. 25, 92-96. 4. Snow, M.R. & Tiekink, E.R.T. (1988). Acta Cryst. B44, 676-677. 5. Spek, A.L. (1988). J. Appl. Cryst. 21, 578-579. 6. Le Page, Y. (1987). J. Appl. Cryst. 20, 264-269. 7. Le Page, Y. (1988). J. Appl. Cryst. 21, 983-984. 8. Beurskens, P.T., Beurskens, G., Gelder, R. de, García-Granda, S., Gould, R.O.,
Israël, R. & Smits, J.M.M. (1999). The DIRDIF-99 program system, Crystallography Laboratory, University of Nijmegen, The Netherlands.
9. Hall, S.R, Allen, F.H. & Brown, I.D. (1991). Acta Cryst. A47, 655-685. 10. Spek, A.L. (2002). PLATON. Program for the Automated Analysis of
Molecular Geometry (A Multipurpose Crystallographic Tool). Version of Feb. 2002. University of Utrecht, The Netherlands.
11. International Tables for Crystallography (1992). Vol. C. Edited by A.J.C. Wilson, Kluwer Academic Publishers, Dordrecht. The Netherlands.
12. Sheldrick, G.M. (1997b). SHELXL-97. Program for the Refinement of Crystal Structures. University of Göttingen, Germany.
13. Meetsma, A. (2002). PLUTO. Molecular Graphics Program. University of Groningen, The Netherlands.
14. Bondi, A. (1964). J. Phys. Chem. 68, 441-451. 15. Spek, A.L. (1990). Acta Cryst. A46, C-34. 16. Spek, A.L. (1994). Am. Crystallogr. Assoc. Abstr. 22, 66. 17. International Tables for Crystallography (1983). Vol. A. Space-group
symmetry, edited by T. Hahn. Dordrecht: Reidel. (Present distributor Kluwer Academic Publishers, Dordrecht).
C31 -C32 -C33 -C34 178.8(3) C37 -C32 -C33 -C34 -0.5(4) C31 -C32 -C37 -C36 -178.7(3) C33 -C32 -C37 -C36 0.6(4) C32 -C33 -C34 -C35 0.0(4) C33 -C34 -C35 -C36 0.4(4) C34 -C35 -C36 -C37 -0.3(4) C35 -C36 -C37 -C32 -0.2(4) The sign of the torsion angle is positive if when looking from atom-2 to atom-3 a clockwise motion of atom-1 would superimpose it on atom-4.
Part III: Structure determination of [Me2-TACN-(CH2)2NBut]La(CCPh)2 (3)
Experimental
X-ray diffraction: Crystal and Molecular Structure.
Suitable colorless colored block-shaped crystals were obtained by recrystallisation
from toluene. The crystals were picked from the mother liquor, to avoid deterioration
due to loss of solvent from the crystal lattice, directly glued on a glass fiber and
transferred into the cold nitrogen stream of the low temperature unit mounted on the
diffractometer.
A crystal with the dimensions of 0.39 x 0.29 x 0.23 mm was mounted on top of a
glass fiber, by using inert-atmosphere handling techniques, and aligned on a Bruker1
SMART APEX CCD diffractometer (Platform with full three-circle goniometer). The
diffractometer was equipped with a 4K CCD detector set 60.0 mm from the crystal.
The crystal was cooled to 100(1) K using the Bruker KRYOFLEX low-temperature
device. Intensity measurements were performed using graphite monochromated Mo-
Kα radiation from a sealed ceramic diffraction tube (SIEMENS). Generator settings
were 50 KV/ 40 mA. SMART was used for preliminary determination of the unit cell
constants and data collection control. The intensities of reflections of a hemisphere
were collected by a combination of 3 sets of exposures (frames). Each set had a
different φ angle for the crystal and each exposure covered a range of 0.3° in ω. A
total of 1800 frames were collected with an exposure time of 10.0 seconds per frame.
The overall data collection time was 8.0 h. Data integration and global cell refinement
was performed with the program SAINT. The final unit cell was obtained from the xyz
centroids of 9288 reflections after integration. Intensity data were corrected for
Lorentz and polarization effects, scale variation, for decay and absorption: a multi-
scan absorption correction was applied, based on the intensities of symmetry-related
reflections measured at different angular settings (SADABS)2, and reduced to Fo2. The
program suite SHELXTL was used for space group determination (XPREP).1
The unit cell3 was identified as triclinic, space group P-1: the E-statistics were
indicative of a centrosymmetric space group.0 Reduced cell calculations did not
indicate any higher metric lattice symmetry0 and examination of the final atomic
coordinates of the structure did not yield extra crystallographic or metric symmetry
elements.6,7
The structure was solved by Patterson methods and extension of the model was
accomplished by direct methods applied to difference structure factors using the
program DIRDIF.8 The positional and anisotropic displacement parameters for the
non-hydrogen atoms were refined. A subsequent difference Fourier synthesis resulted
in the location of most hydrogen atoms; the remaining hydrogen atoms were
generated by geometrical considerations. The hydrogen atom coordinates and
isotropic displacement parameters were refined.
Refinement was frustrated by a disorder problem: from the solution it was clear that a
toluene solvent molecule was highly disordered over an inversion. Attempts to find a
satisfactory disorder model failed. The BYPASS procedure0 was used to take into
account the electron density in the potential solvent area, which resulted in an electron
count of 32, within a volume of 498.4 Å3 in the unit cell.
Final refinement on F2 carried out by full-matrix least-squares techniques converged
at wR(F2) = 0.0842 for 16750 reflections and R(F) = 0.0305 for 14479 reflections
with Fo ≥ 4.0 σ(Fo) and 1054 parameters. The final difference Fourier map was
essentially featureless with a few peaks of max. 2.2( 1) e/Å3 within 1.0 Å from La, but
were neglected/rejected, being artefacts. No other significant peaks (max. = 0.9(1)
e/Å3) having chemical meaning above the general background were observed in the
final difference Fourier syntheses.
The positional and anisotropic displacement parameters for the non-hydrogen atoms
and isotropic displacement parameters for hydrogen atoms were refined on F2 with
full-matrix least-squares procedures minimizing the function Q = h[w(│(Fo2) -
k(Fc2)│)2], where w = 1/[σ2(Fo
2) + (aP)2 + bP], P = [max(Fo2,0) + 2Fc
2] / 3, F0 and Fc
are the observed and calculated structure factor amplitudes, respectively; ultimately
the suggested a (=0.0514) and b (= 0.0) were used in the final refinement.
Crystal data and numerical details on data collection and refinement are given in
Table 1. Final fractional atomic coordinates, equivalent displacement parameters and
anisotropic displacement parameters for the non-hydrogen atoms are given in Table 2.
Molecular geometry data are collected in Table 3. Tables of atom positions,
displacement parameters, comprehensive distances and angles and tables of (Fo2),
(Fc2) and σ(Fo
2) are given as supplementary material8 for this paper. Neutral atom
scattering factors and anomalous dispersion corrections were taken from International
Tables for Crystallography.11
All refinement calculations and graphics were performed on a Pentium-III / Debian-
Linux computer at the University of Groningen with the program packages SHELXL12
(least-square refinements), a locally modified version of the program PLUTO13
(preparation of illustrations) and PLATON10 package (checking the final results for
missed symmetry with the MISSYM option, solvent accessible voids with the SOLV
option, calculation of geometric data and the ORTEP10 illustrations).
References. 1. Bruker (2000). SMART, SAINT, SADABS, XPREP and SHELXTL/NT. Area
Detector Control and Integration Software. Smart Apex Software Reference Manuals. Bruker Analytical X-ray Instruments. Inc., Madison, Wisconsin, USA.
2. Sheldrick, G.M. (2001). SADABS. Version 2. Multi-Scan Absorption Correction Program. University of Göttingen, Germany.
3. Duisenberg, A. J. M. (1992). J. Appl. Cryst. 25, 92-96. 4. Snow, M.R. & Tiekink, E.R.T. (1988). Acta Cryst. B44, 676-677 5. Spek, A.L. (1988). J. Appl. Cryst. 21, 578-579. . 6. Le Page, Y. (1987). J. Appl. Cryst. 20, 264-269. 7. Le Page, Y. (1988). J. Appl. Cryst. 21, 983-984. 8. Beurskens, P.T., Beurskens, G., Gelder, R. de, García-Granda, S., Gould,
Crystallography Laboratory, University of Nijmegen, The Netherlands. 9. Sluis, P. van der & Spek, A.L. (1990). Acta Cryst. A46, 194-201. 10. Hall, S.R, Allen, F.H. & Brown, I.D. (1991). Acta Cryst. A47, 655-685. 11. Spek, A.L. (2003). PLATON. Program for the Automated Analysis of
Molecular Geometry (A Multipurpose Crystallographic Tool). Version of June 2003. University of Utrecht, The Netherlands. 12.International Tables for Crystallography (1992). Vol. C. Edited by A.J.C. Wilson, Kluwer Academic Publishers, Dordrecht. The Netherlands.
13. Sheldrick, G.M. (1997). SHELXL-97. Program for the Refinement of Crystal Structures. University of Göttingen, Germany.
14. Meetsma, A. (2003). PLUTO. Molecular Graphics Program. Version of May 2003. University of Groningen, The Netherlands.
15. Bondi, A. (1964). J. Phys. Chem. 68, 441-451. 16. Spek, A.L. (1990). Acta Cryst. A46, C-34. 17. Spek, A.L. (1994). Am. Crystallogr. Assoc. Abstr. 22, 66. 18. International Tables for Crystallography (1983). Vol. A. Space-group
symmetry, edited by T. Hahn. Dordrecht: Reidel. (Present distributor Kluwer Academic Publishers, Dordrecht).
or F(h) = Fo(h) exp (-8π2Uiso(sin(θ)/λ)2) Table 3. Data on the geometry. Standard deviations in the last decimal place are given in parentheses. Residue: 1.