Products of the reaction of 9-nickelafluorenyllithium complexes with water

Article abstract of DOI:10.1021/om800329u

Reactions of 9-nickelafluorenyllithium complexes with water were carried out. Trinickel clusters with aryne ligands were formed (via aromatic C-H bond activation by a nickel atom), whose crystal and molecular structures were determined by single-crystal X-ray analysis.

Full text of DOI:10.1021/om800329u

3618
Organometallics 2008, 27, 3618–3621
Products of the Reaction of 9-Nickelafluorenyllithium Complexes
with Water
Piotr Buchalski,*,† Patryk Jadach,† Antoni Pietrzykowski,† Kinga Suwin´ska,‡
Lucjan Jerzykiewicz,§ and Jarosław Sadło
Faculty of Chemistry, Warsaw UniVersity of Technology, Koszykowa 75, 00-662 Warsaw, Poland, Institute
of Physical Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland,
Faculty of Chemistry, UniVersity of Wrocław, Joliot-Curie 14, 50-353 Wrocław, Poland, and Institute of
Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
ReceiVed April 14, 2008
Scheme 1. Reactions of Complexes 1 with Water
Summary: Reactions of 9-nickelafluorenyllithium complexes with
water were carried out. Trinickel clusters with aryne ligands
were formed (Via aromatic C-H bond actiVation by a nickel
atom), whose crystal and molecular structures were determined
by single-crystal X-ray analysis.
Introduction
We have recently published the synthesis and structural
characterization of 9-nickelafluorenyllithium compounds.1 To
extend our knowledge of their properties, we studied their
reactivity toward various reagents. In this paper we present the
results of our studies on reactions of these compounds with
water. The reaction is not a simple hydrolysis. A C-H bond of
the phenyl ring is activated, and trinickel complexes with
phenylbenzyne are formed among other products. C-H bond
activation by transition metal complexes has been intensively
studied in recent years due to its potential applications in
synthesis.2
Benzyne and its derivatives are a specific type of alkynes
derived from benzene. They are very reactive and cannot be
isolated as free species,3 but can be stabilized as complexes
with various early and late transition metals, similar to those
formed with alkynes, which can be bonded to one or more metal
centers in various ways.4 Several structurally characterized
nickel complexes with aryne ligands containing one,5 two,6 or
three7 nickel atoms are known.
The products were separated by column chromatography on
neutral alumina deactivated with 5% water. Three colored bands
were collected. The first, green fraction from the reaction of 1a
with water contained traces of nickelocene. The second, red
fraction contained π-allyl complex 2a (yield 28%). It was
characterized by EIMS, EI HRMS, and 1H and 13C NMR
spectroscopy. Recrystallization from ethanol afforded crystals
of 2a suitable for X-ray diffraction. The molecular structure of
2a is presented in Figure 1. Crystal data, data collection, and
refinement parameters are given in Table 1. The compound
crystallizes in the monoclinic crystal system. The cyclopentenyl
ring exhibits an “open envelope” conformation. The nickel atom
is bonded to the cyclopentadienyl ring in η5 mode and to the
cyclopentenyl ring in η3 mode. The hinge angle between the
planes C1-C2-C4-C5 and C2-C3-C4 is 26.8°. The bond
lengths between the nickel atom and carbon atoms (Ni-C3
1.884(4) Å, Ni-C2 2.062(4) Å, N-C4 1.981(5) Å) are typical
for π-allyl-nickel complexes.8 The third, brown fraction con-
tained a mixture of trinickel clusters 3a and 4a. They were
unstable and decompose during chromatography, so it was
impossible to separate them from each other and to obtain
crystals for X-ray measurements. They were identified by the
EIMS spectrum of their mixture, which revealed the parent ion
at m/e 521 (58Ni calc) with an isotopic pattern characteristic
for three nickel atoms in the molecule, and by an EI HRMS
spectrum.
Results and Discussion
The reactions of compounds 1a and 1b with deoxygenated
water have been carried out in a mixture of toluene and
diethyl ether at temperatures ranging from 0 °C to room
temperature. Three types of products were formed in these
reactions (Scheme 1).
* Corresponding author. Tel: +48 22 234 78 59. Fax: +48 22 234 54
62. E-mail: pjb@ch.pw.edu.pl.
† Warsaw University of Technology.
‡ Institute of Physical Chemistry of the Polish Academy of Sciences.
§ University of Wrocław.
Institute of Nuclear Chemistry and Technology.
(1) Buchalski, P.; Grabowska, I.; Kamin´ska, E.; Suwin´ska, K. Orga-
nometallics 2008, 27, 2346–2349.
(2) See for example: (a) Labinger, J. A.; Bercaw, J. E. Nature 2002,
417, 507. (b) Godula, K.; Sames, D. Science 2006, 312, 67. (c) Lersch, M.;
Tilset, M. Chem. ReV. 2005, 105, 2471. (d) Shilov, A. E.; Shul’pin, G. B.
Chem. ReV. 1997, 97, 2879. (e) Liang, L.-C.; Chien, P.-S.; Huang, Y.-L.
J. Am. Chem. Soc. 2006, 128, 15562.
(3) Wenk, H. H.; Winkler, M.; Sander, W. Angew. Chem., Int. Ed. 2003,
42, 502.
(4) Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. ReV. 1983, 83, 203.
10.1021/om800329u CCC: $40.75
2008 American Chemical Society
Publication on Web 06/25/2008

Notes
Organometallics, Vol. 27, No. 14, 2008 3619
pattern characteristic for three nickel atoms in the molecules.
Compounds 3b and 4b are paramagnetic. The EPR spectra of
both compounds in benzene and in the solid state were identical.
There were no signals in the EPR spectra at room temperature.
At 77 K there was an isotropic single Lorentzian line with g
factor 2.023 and of line width 144 G. Crystals of 3b and 4b
suitable for X-ray diffraction studies were obtained from hexane
solutions. Their molecular structures are presented in Figures 2
and 3, respectively. Crystal data, data collection, and refinement
parameters are given in Table 1. Both compounds crystallize
in a monoclinic crystal system. Three nickel atoms form a
triangle. The phenylbenzyne ligand is bonded to the trinickel
core by two σ bonds and one π bond (2σ + π or µ3-η2), which
is similar to the bonding mode of alkyne to three nickel atoms
in previously described clusters.9 This type of a bonding mode
is commonly found in homo- and heterometallic alkyne clusters
and is also common for isonitriles.5 The Ni-Ni distances
(2.38-2.45 Å) are within the range of nickel-nickel single
bonds.
The proposed course of the reaction is depicted in Schemes
2 and 3. The formation of clusters 3 and 4 most probably occurs
via nickel-mediated aromatic C-H bond activation. It can be
assumed that during hydrolysis of 1 an unstable 16 VE species
5 is formed, which is the precursor of cluster 3. Species 5
isomerizes via nickel-mediated hydrogen transfer to the species
7, which is the precursor of cluster 4.
Such isomerization is evidence for C-H bond activation in
arenes by nickel. It also demonstrates that the nickel atom can
migrate with respect to the aromatic ring. Johnson and co-
workers recently postulated that such migration can occur in a
difluorobenzynenickel complex.6a,b
In conclusion, we have shown that the course of the
hydrolysis of 9-nickelafluorenyllithium complexes is compli-
cated, leading to several organonickel products: π-allyl com-
plexes and trinickel clusters with aryne ligands. It appears likely
that the formation of these compounds proceeds via aromatic
C-H bond activation by nickel.
Figure 1. ORTEP view of the molecular structure of 2a. Thermal
ellipsoids are drawn at the 30% probability level. Hydrogen atoms
were omitted for clarity. Selected interatomic distances (Å) and
angles (deg): Ni-C2 2.062(4), Ni-C3 1.884(4), Ni-C4 1.981(5),
Ni-Cg 1.768(2), C1-C2 1.511(5), C2-C3 1.408(7), C3-C4
1.419(7), C4-C5 1.522(6), C1-C5 1.537(6), C2-C3-C4 105.1(4),
Ni-C3-C2 76.0(3), Ni-C3-C4 72.1(2), C2-Ni-C4 67.4(2).
Therefore we decided to synthesize complexes with meth-
ylcyclopentadienyl ligands. Compound 1b was synthesized from
dilithiobiphenyl and 1,1′-dimethylnickelocene (63% yield). It
is much more soluble than 1a in organic solvents and was
1
characterized on the basis of H and 13C NMR spectra. The
reaction of 1b and water was carried out in a mixture of toluene
and diethyl ether. The products were separated by column
chromatography on neutral alumina deactivated with 5% water.
Three colored bands were collected. The first, green fraction
contained traces of 1,1′-dimethylnickelocene. The second, red
fraction contained π-allyl complex 2b (yield 16%). It was
characterized by EIMS (the parent ion at m/e 370 (58Ni calc)),
Experimental Section
All reactions were carried out in an atmosphere of dry argon or
nitrogen using Schlenk flask techniques. Solvents were dried by
1
1
EI HRMS, and H and 13C NMR spectra. H NMR and 13C
NMR spectra of 2b are difficult to analyze owing to the number
of isomers that may be formed during addition of the biphenyl
group to the methylcyclopentadienyl ring. The third, brown
fraction contained a mixture of trinickel clusters 3b and 4b.
The mixture was chromatographed again, and two brown
fractions of compounds 3b and 4b were separated. Their EIMS
showed the parent ions at m/e 563 (58Ni calc) with an isotopic
1
conventional methods. H and 13C NMR spectra were measured
on a Varian Mercury 400BB instrument. Mass spectra were
recorded on an AMD-604 spectrometer. EPR spectra were measured
on a Bruker ESP 300 spectrometer in X-band. Compound 1a was
synthesized according to the method described previously.1
Synthesis of 1b. 2,2′-Dibromobiphenyl (4.00 g, 12.8 mmol) and
150 mL of hexane were placed in a Schlenk flask. Then 25.6 mmol
of n-butyllithium in hexane was added at room temperature. The
reaction was carried out for 4 days. The white precipitate of 2,2′-
dilithiobiphenyl was washed three times with hexane and dried
under vacuum. Then 200 mL of diethyl ether and 2.75 g (12.7
mmol) of 1,1′-dimethylnickelocene were added. The reaction was
carried for 2 days at room temperature. The resulting precipitate
was allowed to settle, and the clear supernatant solution of 1b was
transferred to another Schlenk flask. A 20 mL amount of dimethox-
yethane was added to the solution of 1b, forming a yellow
precipitate. Solvents were removed under reduced pressure, and
the solid residue was dissolved in 15 mL of warm dimethoxyethane.
Red crystals were obtained after cooling the solution to -15 °C.
(5) (a) Garcia, J. J.; Brunkan, N. M.; Jones, W. D. J. Am. Chem. Soc.
2002, 124, 9547. (b) Retboll, M.; Edwards, A. J.; Rae, A. D.; Willis, A. C.;
Bennet, M. A.; Wenger, E. J. Am. Chem. Soc. 2002, 124, 8348. (c) Bennet,
M. A.; Hambley, T. W.; Roberts, N. K.; Robertson, G. B. Organometallics
1985, 4, 1992.
(6) (a) Keen, A. L.; Johnson, S. A. J. Am. Chem. Soc. 2006, 128, 1806.
(b) Keen, A. L.; Doster, M.; Johnson, S. A. J. Am. Chem. Soc. 2007, 129,
810. (c) Bennet, M. A.; Drage, J. S.; Griffiths, K. D.; Roberts, N. K.;
Robertson, G. B.; Wickramasinghe, W. A. Angew. Chem., Int. Ed. 1988,
27, 941.
(7) Bennet, M. A.; Griffiths, K. D.; Okano, T.; Parthasarathi, V.;
Robertson, G. B. J. Am. Chem. Soc. 1990, 112, 7047.
(8) See for example: (a) Schneider, J. J.; Kru¨ger, C. Chem. Ber. 1992,
125, 843. (b) Wiederhold, M.; Behrens, U. J. Organomet. Chem. 1994,
476, 101. (c) Pasynkiewicz, S.; Pietrzykowski, A.; Bukowska, L.; Słupecki,
K.; Jerzykiewicz, L. B.; Urban´czyk-Lipkowska, Z. J. Organomet. Chem.
2000, 604, 241. (d) Denniger, U.; Schneider, J. J.; Wilke, G.; Goddard, R.;
Kro¨mer, R.; Kru¨ger, C. J. Organomet. Chem. 1993, 459, 349.
(9) (a) Pasynkiewicz, S.; Pietrzykowski, A.; Kryza-Niemiec, B.; Jerzyk-
iewicz, L. B. J. Organomet. Chem. 2000, 593, 245. (b) Pietrzykowski, A.;
Buchalski, P.; Pasynkiewicz, S.; Lipkowski, J. J. Organomet. Chem. 2002,
663, 249.

3620 Organometallics, Vol. 27, No. 14, 2008
Notes
Table 1. Crystal Data and Structure Refinement Parametersa
2a 3b
4b
empirical formula
cryst size
cryst syst
space group
unit cell dimens
C22H20Ni
C30H29Ni3
C30H29Ni3
0.45 × 0.25 × 0.2 mm
monoclinic
P21
a ) 5.7888(2) Å
b ) 13.1587(6) Å
c ) 11.1799(5) Å
ꢀ ) 103.979(2)°
826.44(6) Å3
2
0.5 × 0.4 × 0.1 mm
monoclinic
P21/c
a ) 12.505(2) Å
b ) 9.792(2) Å
c ) 19.219(3) Å
ꢀ ) 94.32(2)°
2346.7(7) Å3
4
0.6 × 0.4 × 0.1 mm
monoclinic
P21/n
a ) 16.393(2) Å
b ) 9.319(2) Å
c ) 17.292(2) Å
ꢀ ) 109.71(2)°
2486.9(7) Å3
4
volume
Z
fw
343.09
565.66
565.66
density (calcd)
temperature
absorp coeff
F(000)
1.379 Mg · m-3
293(2) K
1.601 Mg · m-3
100(1) K
1.511 Mg · m-3
100(1) K
1.170 mm-1
360
2.399 mm-1
1172
2.264 mm-1
1172
radiation
θ range for data collection
index ranges
Mo KR (λ ) 0.71073 Å, graphite monochromator)
1.88-27.86°
3.27-28.39°
3.25-28.52°
-7 e h e 7,
-15 e h e 16,
-19 e h e 21,
-12 e k e 12,
-18 e l e 21
-17 e k e 17,
-14 e l e 14
7324/2037 [Rint ) 0.041]
-12 e k e 10,
-25 e l e 24
no. of reflns collected/unique
refinement method
15 631/5420 [Rint ) 0.0287]
full-matrix least-squares on F2
5420/0/298
10 034/5434 [Rint ) 0.0877]
no. of data/restraints/params
2037/0/208
1.051
5434/0/298
goodness-of-fit on F2
1.066
0.955
final R indices [I > 2σ(I)]
R indices (all data)
largest diff peak and hole
R ) 0.037, wR ) 0.085
R ) 0.049; wR ) 0.089
0.411 and -0.497 e · Å-3
R ) 0.028, wR ) 0.065
R ) 0.039; wR ) 0.068
0.475 and -0.434 e · Å-3
R ) 0.065, wR ) 0.164
R ) 0.111; wR ) 0.188
0.575 and -0.804 e · Å-3
a Weighting scheme (where P ) (Fo + 2Fc )/3): For 2a: w-1 ) σ2 (Fo + (0.0362P)2 - 0.4535P. For 3b: w-1 ) σ2 (Fo + (0.0385P)2 + 0.0000P.
2
2
2
2
For 4b: w-1 ) σ2 (Fo + (0.1015P)2 + 0.0000P.
2
Figure 3. ORTEP view of the molecular structure of 4b. Thermal
ellipsoids are drawn at the 20% probability level. Hydrogen atoms
were omitted for clarity. Selected interatomic distances (Å) and
angles (deg): Ni2-Ni1 2.383(1), Ni2-Ni3 2.403(1), Ni1-Ni3
2.449(1), Ni2-Cg 1.735(3), Ni1-Cg 1.770(2), Ni3-Cg 1.778(9),
Ni2-C41 1.983(5), Ni2-C42 2.013(5), Ni1-C42 1.862(5), Ni3-C41
1.884(5),C41-C421.403(7),Ni2-Ni1-Ni359.62(3),Ni2-Ni3-Ni1
58.83(3), Ni1-Ni2-Ni3 61.54(3), C41-Ni2-C42 41.1(2).
Figure 2. ORTEP view of the molecular structure of 3b. Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms
were omitted for clarity. Selected interatomic distances (Å) and
angles (deg): Ni1-Ni2 2.3871(5), Ni1-Ni3 2.4071(6), Ni2-Ni3
2.4475(5), Ni1-Cg 1.73(1), Ni2-Cg 1.76(1), Ni3-Cg 1.769(1),
Ni1-C42 1.996(2), Ni1-C43 2.003(2), Ni2-C42 1.898(2), Ni3-C43
1.871(2),C42-C431.409(3),Ni1-Ni2-Ni359.70(2),Ni1-Ni3-Ni2
58.90(2), Ni2-Ni1-Ni3 61.40(1), C42-Ni1-C43 41.27(8).
Scheme 2
The crystals were dried under vacuum at 50 °C. 1b was obtained
1
as a yellow powder (3.12 g, 8.1 mmol, 63%). H NMR (C6D6): δ
3
3
(ppm): 7.76 (d, J ) 7.2 Hz, 2H, Ph), 7.55 (d, J ) 7.2 Hz, 2H,
3
3
Ph), 7.09 (t, J ) 7.2 Hz, 2H, Ph), 6,87 (t, J ) 7.2 Hz, 2H, Ph),
3
3
5.38 (t, J ) 2,4 Hz, 2H, Ph), 5.27 (t, J ) 2,4 Hz, 2H, Ph), 2.50
(s, 6H, CH3 (DME)), 2.33 (s, 4H, CH2 (DME)), 2.21 (s, 3H, CH3
(MeCp)). 13C NMR (C6D6) δ (ppm): 167.51 (Ph), 153.80 (Ph),
145.21 (Ph), 123.72 (Ph), 122.69 (Ph), 120.95 (Ph), 103.65 (C,
MeCp), 91.32 (CH, MeCp), 88.93 (CH, MeCp), 68.84 (CH2, DME),
58.90 (CH3, DME), 13.87 (CH3, MeCp). Anal. Calcd for
C22H25LiNiO2: C, 68.27; H, 6.51. Found: C, 68.10; H, 6.62.
Reaction of 1a with Water. 1a (1.106 g, 3.0 mmol), toluene
(35 mL), and diethyl ether (35 mL) were placed in a Schlenk flask.
The solution was cooled to 0 °C. Then 30 mL of deoxygenated
water was slowly added. The mixture was stirred for 30 min at 0
°C, then warmed slowly to room temperature and filtered through
a bed of alumina. The organic layer solution was concentrated to

Notes
Organometallics, Vol. 27, No. 14, 2008 3621
Scheme 3
matrix least-squares with SHELXL-97.13 All hydrogen atoms were
placed in calculated positions and refined using a riding model.
Reaction of 1b with Water. The reaction was carried out
analogously to the previous one using 2.413 g (6.3 mmol) of 1b,
toluene (30 mL), and diethyl ether (30 mL). Three colored
chromatographic bands were separated and collected. The first,
green fraction (hexane/toluene, 10:1) after evaporation to dryness
gave traces of a solid identified by EIMS spectroscopy as 1,1′-
dimethylnickelocene. The second, red fraction (hexane/toluene, 6:1)
gave a solid identified as 2b (yield 0.184 g, 0.5 mmol, ca. 16%).
EIMS (70 eV) m/e (rel int) (58Ni): 370 (13%, M+), 290 (100%,
C18H16Ni+), 275 (33%, C17H13Ni+), 215 (14%, C17H11+). EI
HRMS: obsd 370.12288, calcd for C24H24(58Ni) 370.12315. 1H
NMR (C6D6) δ (ppm): 6.70-8.10 (m), 4.80-5.15 (m), 3,78 (s),
3.63 (s), 3.45 (s), 2.78 (m), 1.85 (s), 1.83 (s), 1.81 (s), 1.01 (s),
0.85-1.30 (m). 13C NMR (C6D6) δ (ppm): 125-144, 82-94,
62-68, 40-46, 12-22. Complex spectra owing to several possible
isomers. Anal. Calcd for C24H24Ni: C, 77.67 H, 6.52. Found: C,
77.34; H, 6.35. The third, brown fraction (hexane/toluene, 1:1) gave
a brown solid identified as a mixture of 3b and 4b. This fraction
was chromatographed again on a smaller column. Two brown
fractions were collected. The first fraction (hexane/toluene, 1:1)
gave 0.202 g (0.36 mmol, 17%) of a brown solid identified as 3b.
The second brown fraction (hexane/toluene, 1:1) gave 0.033 g (0.06
mmol, 3%) of a brown solid identified as 4b. Crystals of 3b and
4b suitable for X-ray measurements were obtained from a hexane
solution. EIMS of 3b and 4b (70 eV) m/e (rel int) (58Ni): 563 (84%,
M+), 481 (29%, C24H19Ni3+), 403 (7%, C18H13Ni3+), 331 (18%,
C12H13Ni3+), 288 (5%, C18H14Ni+), 216 (6%, C12H14Ni+), 152 (3%,
C12H8+), 136 (4%, C6H6Ni+). EI HRMS: obsd 563.03273, calcd
for C30H29(58Ni)3 563.03297. Anal. Calcd for 3b C30H29Ni3: C,
63.70 H, 5.17. Found: C, 63.54; H, 5.35. Anal. Calcd for 4b
C30H29Ni3: C, 63.70 H, 5.17. Found: C, 63.82; H, 5.32.
approximately 10 mL. Alumina was added and the solvent was
removed under vacuum. The products, absorbed on alumina, were
placed at the top of the column and chromatographed on alumina
(deactivated with 5% water) with hexane/toluene mixtures as
eluents. Three colored bands were separated and collected. The first
green fraction (hexane/toluene, 10:1) after evaporation to dryness
gave traces of a solid identified by EIMS spectroscopy as
nickelocene.
The second, red fraction (hexane/toluene, 5:1) gave a solid
identified as 2a (yield 0.142 g, 0.42 mmol, ca. 28%). Crystals of
2a suitable for X-ray measurements were obtained from an ethanol
solution. EIMS (70 eV) m/e (rel int) (58Ni): 342 (8%, M+), 304
(26%, C19H18Ni+), 276 (100%, C17H14Ni+), 215 (36%, C17H11+),
123 (4%, C5H5Ni+). EI HRMS: obsd 342.09298, calcd for
C22H20(58Ni) 342.09185. 1H NMR (C6D6) δ (ppm) (atom numbering
as in Figure 1): 7.07-7.93 (m, 9H, Ph), 5.20 (s, 5H, Cp), 5.06 (m,
1H, CH), 3.87 (m, 1H, CH), 3.59 (m, 1H, CH), 2.60 (m, 1H, CH),
0.95 (m, 2H, CH2). 13C NMR (C6D6) δ (ppm): 142.99 (Ph), 142.94
(Ph), 141.72 (Ph), 130.02 (Ph), 129.49 (Ph), 128.33 (Ph), 126.89
(Ph), 126.78 (Ph), 126.13 (Ph), 89.30 (Cp), 82.37 (CH), 65.71 (CH),
61.38 (CH), 45.08 (CH) (3), 39.80 (CH2). Anal. Calcd for C22H20Ni:
C, 77.02 H, 5.88. Found: C, 76.82; H, 6.05. The third, brown
fraction (hexane/toluene, 1:1) gave 0.108 g (0.21 mmol, 21%) of a
brown solid identified as a mixture of 3a and 4a. Repeated
chromatography of this fraction did not lead to the separation of
these products and caused their decomposition. EIMS (70 eV) m/e
(rel int): (58Ni): 521 (90%, M+), 455 (55%, C22H17Ni3+), 340 (20%,
C22H18Ni+), 275 (14%, C17H13Ni+), 215 (28%, C17H11+), 188 (37%,
C10H10Ni+), 154 (14%, C12H10+), 123 (15%, C5H5Ni+). EI HRMS:
obsd 520.98570, calcd for C27H23(58Ni)3 520.98602.
Crystal structure determination of 3b and 4b: Preliminary
examination and intensity data collections were carried out on a
KUMA CCD KM-4 κ-axis diffractometer with graphite-monochro-
mated Mo KR.14 All data were corrected for Lorentz, polarization,
and absorption effects. Data reduction and analysis were carried
out with the Oxford Diffraction programs. The structures were
solved by direct methods and refined using full-matrix least-squares
on all F2 data with SHELXTL software.15 All non-hydrogen atoms
were refined anisotropically, and hydrogen atoms were included
in calculated positions with isotropic thermal parameters.
Acknowledgment. This work was financially supported
by the Polish Ministry of Education and Science (grant no.
PBZ-KBN-118/T09/03).
Crystal structure determination of 2a: The crystal was sealed in
a glass capillary under a nitrogen stream. X-ray data were collected
on a Nonius KappaCCD diffractometer. The diffractometer control
program was Collect,10 unit cell parameters and data reduction was
performed with Denzo and Scalepak,11 and the structure was solved
by direct methods with SHELXS-9712 and refined on F2 by full-
Supporting Information Available: CIF files giving X-ray
crystallographic data for the structure determinations of 2a, 3b, and
4b. This material is available free of charge via the Internet at
http://pubs.acs.org.
OM800329U
(10) Nonius, B. V.“Collect” data collection software, 1998.
(11) Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data
Collected in Oscillation Mode. In Methods in Enzymology, Vol. 276:
Macromolecular Crystallography, part A; Carter, C. W., Jr., Sweet, R. M.,
Eds.; Academic Press: New York, 1997; pp 307-326.
(12) Sheldrick, G. M. SHELXS-97. Acta Crystallogr., Sect. A 1990, 46,
467.
(13) Sheldrick, G. M. SHELXL-97, Program for the refinement of crystal
structures; University of Go¨ttingen: Go¨ttingen (Germany), 1997.
(14) Oxford Diffraction. CrysAlis CCD and CrysAlis RED, Versions
1.171; Oxford Diffraction Ltd.: Abingdon, Oxfordshire, England, 2004.
(15) Sheldrick, G. M. SHELXTL, Version 5.10; Bruker AXS Inc.:
Madison, WI, 1997.