Synthesis and crystal structure of 1-(4-fluorophenyl)-and 1-(4-dimethylamino)phenylgermatranes

Article abstract of DOI:10.1007/s10593-008-0082-9

The X-ray crystal structure of 1-(4-fluorophenyl)- and 1-(4- dimethylaminophenyl)germatranes reveals that the germanium atom is pentacoordinated and adopts a trigonal bipyramidal geometry. The fluorophenyl and dimethylaminophenyl groups and the nitrogen atom each occupy an apical position with the transannular N→Ge bond of 2.192(3) and 2.249(3) A; the deviation of the Ge atom from the O(2)-O(8)-O(9) plane is 0.2306(4) and 0.2693(3) A, correspondingly. 2008 Springer Science+Business Media, Inc.

Full text of DOI:10.1007/s10593-008-0082-9

Chemistry of Heterocyclic Compounds, Vol. 44, No. 5, 2008
SYNTHESIS AND CRYSTAL STRUCTURE
OF 1-(4-FLUOROPHENYL)-AND 1-(4-DIMETHYL-
AMINO)PHENYLGERMATRANES
E. Lukevics, L. Ignatovich, T. Shul'ga, S. Belyakov
The X-ray crystal structure of 1-(4-fluorophenyl)- and 1-(4-dimethylaminophenyl)germatranes reveals that the
germanium atom is pentacoordinated and adopts a trigonal bipyramidal geometry. The fluorophenyl and
dimethylaminophenyl groups and the nitrogen atom each occupy an apical position with the transannular
N→Ge bond of 2.192(3) and 2.249(3) Å; the deviation of the Ge atom from the O(2)−O(8)−O(9) plane is
0.2306(4) and 0.2693(3) Å, correspondingly.
Keywords: germatranes, crystal structure, synthesis, transannular N→Ge bond.
The transannular N→Ge bond length in 1-substituted germatranes containing the Ge−C bond depends on
the hybridization state of the C atom and the electronegativity of the substituents bound to this atom. For Csp
3
substituents (alkyl, cycloalkyl) it is in the range 2.24−2.27 Å [1] being the longest in 1-ada- mantylgermatrane
(2.266 Å) [2]. Introduction of electronegative substituents into the alkyl group significantly shortens the N→Ge
bond (2.167 for CH2Cl, 2.146 for CHCl2, and 2.108 Å for CF3) [1]. This bond is shorter for germatranes with
Csp substituents (aryl) but it is less influenced by the substituents in the aryl group, e.g. 2.156 for C F [3] and
2
6
5
2.212 Å for C6H5 [3, 4]. The difference is even smaller for monosubstituted arylgermatranes (Table 1). This may
be due to the relatively small substituent electronic effects in the investigated arylgermatranes. Therefore we
decided to synthesize and investigate the molecular structure of arylgermatranes containing substituents with
different electronic effects (F and Me2N).
The 4-fluorophenylgermatrane (1) was prepared from 1-fluoro-4-iodobenzene by the germanium
dibromide insertion method [4] and 4-dimethylaminophenylgermatrane (2) from N,N-dimethylaniline by the
substitution reaction with germanium tetrachloride [5] followed by hydrolysis and cyclization with
triethanolamine.
O
N
R
Ge
O
O
1 R = F, 2 R = NMe2
In the crystal structure of germatrane 1 (Fig. 1) the molecules are packed as on a chessboard: the center
of negative charges of one molecule corresponds to the positive center of another molecule (Fig. 2). The
molecules are packed approximately parallel to the main symmetry axis (space group P 21). Thus, the crystal
__________________________________________________________________________________________
Latvian Institute of Organic Synthesis, Riga, LV-1006; e-mail: ign@osi.lv. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 5, pp. 776-781, May, 2008. Original article submitted March 06, 2008.
0009-3122/08/4405-0615©2008 Springer Science+Business Media, Inc.
615

structure of germatrane 1 is chiral in spite of the absence of asymmetric atoms. Compound 1 is characterized by
a significant value of the dipole moment (calculated value 4.99 D), which is directed along N−Ge−C6H4F bonds.
This direction is almost coaxial to the positive direction of the monoclinic axis (y axis). Therefore, in crystals 1
the dipole moments are summarized and these crystals possess the piezoelectric effect: they are polarized and
stick to the internal surface of vessels.
Fig. 1. Molecular structure of 1-(4-fluorophenyl)germatrane (1).
Fig. 2. A packing diagram for germatrane 1, viewed along the x axis.
The length of the intramolecular transannular N→Ge bond for 4-fluorophenylgermatrane 1 equals
2.192(3) Å. It is a relatively short value for arylgermatranes (Table 1). The deviation (∆Ge) of the Ge atom from
the three oxygen atoms plane in compound 1 is 0.2306(4) Å. The mean bond length for Ge−O is 1.789(4), and
the length of Ge−C bond is 1.949(5) Å; the value of N→Ge−C valence angle is 176.8(2)°, and the mean values
of angles N−Ge−O, O−Ge−C, and O−Ge−O are 82.6(1), 97.4(2), and 118.4(2)°, correspondingly.
616

TABLE 1. The Principal Geometrical Parameters of R−Ge(OCH2CH2)3N
Refe-
rences
R
d (Ge−N), Å
d (Ge−C), Å
∠C−Ge−N, deg
∆Ge, Å
4-Me2NC6H4
2-MeC6H4
4-MeC6H4
3-MeC6H4
C6H5
2.249
2.230
2.217
2.214
2.212
2.192
2.156
2.211
2.208
2.219
2.247
1.941
1.940
1.946
1.947
1.947
1.949
1.990
1.961
1.948
1.948
179.8
144.2
179.0
176.3
177.5
176.8
176.3
178.7
177.6
178.9
0.269
0.263
0.245
0.253
0.238
0.231
0.2
This work
[4]
[4]
[4]
[4]
4-FC6H4
This work
[3]
C6F5
4-EtOOCC6H4
4-BrC6H4
4-(2-Thienyl)C6H4
0.238
0.227
0.263
0.231
[7]
[8]
[9]
Fig. 3. Molecular structure of 1-(4-dimethylaminophenyl)germatrane (2).
Fig. 4. A packing diagram for germatrane 2 (for the sake of clarity, H atoms have
been omitted, the bonds between disordered atoms are shown by double thin lines).
617

The form and volume of compound 2 molecules are near to these in compound 1. At the same time, for
molecules 2 the dipole moment (1.398 D) is three and a half times smaller than that for molecule 1. Possibly, it is
why the molecular packing of germatrane 1 is not realized for the germatrane 2, and the crystal structure 2 (Fig. 3)
is not isomorphous to the structure 1. The molecules 2 are packed in a centrosymmetrical orthorhombic lattice
(space group Pnma); each molecule lies in a special position (symmetry plane m). However, the germatrane cage
does not possess symmetry planes. Thus, packing of molecules 2 in this space group is possible only if structure
disorder occurs (Fig. 4). The symmetry planes m are perpendicular to the phenyl rings of germatrane 2. Two
carbon atoms of the phenyl group and both nitrogen atoms, and germanium atoms lie in the symmetry plane. All
oxygen and carbon atoms of the atrane cage are disordered. The occupation g-factors for these atoms are 0.5.
The value of the N→Ge donor-acceptor bond for germatrane 2 is 2.249(3) Å. It is the longest bond
found for arylgermatranes (Table 1). The Ge−C bond (1.941(3) Å) in germatrane 2 is shorter than in germatrane
1 in accordance with the conclusions of [6], where it has been shown that lengthening of transannular N→Ge
bonds leads to shortening of Ge−C bonds. The bond angle N→Ge−C in compound 2 (179.8(1)°) is practically
flat, and the mean values of angles N−Ge−O, O−Ge−C, and O−Ge−O are 81.4(1), 98.6(2), and 117.8(3)°,
respectively; the ∆Ge value is 0.2693(3) Å and the mean value of Ge−O bond lengths is 1.774(3) Å.
Thus the introduction of fluorine substituent into position 4 of the aryl ring of phenylgermatrane
shortens the N−Ge distance, but the introduction of the electron-donor dimethylamino group, on the contrary,
lengthens it. However, the differences between them and unsubstituted phenylgermatrane are still small.
EXPERIMENTAL
1H NMR spectra were measured on a Varian Mercury-200 instrument (200 MHz) using CDCl3 as a
solvent and TMS as the internal standard. Mass spectra were registered on an GC-MS HP 6890 (70 eV).
Elemental analyses were performed on a EA 1108 Carlo Erba instrument.
The molecular dipole moments for germatranes 1 and 2 were calculated by the quantum-chemical
MNDO method using an approach analogous to [6].
1-(4-Fluorophenyl)germatrane (1). A mixture of 1-fluoro-4-iodobenzene (17 mmol) and the dioxane
complex of germanium(II) dibromide (5 mmol) was boiled in "Pierce" for 18 h under Ar. The reaction mixture
was analyzed by GC. The resultant yellow solution was transported to a 3-neck flask under Ar. An ethanolic
solution of triethylamine (17 mmol) was added dropwise to 4-fluorophenyldibromoiodogermane solution in abs.
Et2O (5 ml), cooled to 0°C, followed by heating to room temperature and boiling for 2 h. After cooling, pentane
(10 ml) was added and the triethylamine salt was filtred off. Triethanolamine (5 mmol) in an ethanol solution (8
ml) was added dropwise to the filtrate cooled to 0°C. The reaction mixture was stirred at room temperature for 1
1
h, cooled to 0°C, and 1-(4-fluorophenyl)germatrane (58%) was filtered off. H NMR spectrum, δ, ppm (J, Hz):
2.93 (6H, t, J = 6.0, CH2N); 3.90 (6H, t, J = 6.0, CH2O); 6.82-7.86 (4H, m, C6H4). GC-MS (m/z): 408 [M+] (5),
327 [M+ −Br] (100), 234 (5), 153 [GeBr] (30), 75 (15), 50 (10). The single crystals were grown from chloroform
by slow evaporation of the solvent, mp 188-189°C. Found, %: C 45.34; H 4.98; N 4.40. C12H16FGeNO3.
Calculated, %: C 45.92; H 5.14; N 4.46.
1-(4-Dimethylaminophenyl)germatrane (2). Germatrane 2 was synthesized by the known method [5].
Crystals of germatrane 2 suitable for X-ray study were grown from ethanol solution, mp 236-238°C (235-238°C
[5]). Found, %: C 49.24; H 6.48; N 8.10. C14H22GeN2O3. Calculated, %: C 49.61; H 6.54; N 8.27.
X-Ray crystallography. For X-ray crystal structure analysis of compounds 1 and 2 an automatic single-
crystal Nonius Kappa CCD diffractometer with MoKα radiation (λ = 0.71073 Å) was used for intensity data
collection. Reflection intensities were collected at room temperature (293K) using the φ and ω scan technique.
Other crystallographic, measurement, and refinement data for compounds 1 and 2 are given in Table 2.
618

TABLE 2. Crystal Data, Measurement Conditions and Refinement Data for
Compounds 1 and 2
1
2
Molecular formula
Molecular weight, Mr
Crystal size, mm3
Crystal system
C12H16FGeNO3
313.85
C14H22GeN2O3
338.93
0.10×0.12×0.25
Monoclinic
P 21
0.13×0.17×0.22
Orthorhombic
Pnma
Space group
Cell parameter:
a, Å
6.7526(3)
9.6962(3)
9.9677(5)
102.524(1)
11.0570(2)
11.2904(2)
12.1708(3)
90.0
b, Å
c, Å
β, deg
Unit cell volume, V, Å3
Molecular multiplicity, Z
F(000)
Crystal density, Dcalc, g/cm3
Absorption coefficient, µ, mm−1
637.10(5)
2
1519.35(5)
4
320
704
1.636
2.416
1.482
2.025
Data collection:
2θmax
55.0
57.0
h
k
l
-8→8
-12→12
-12→12
-14→14
-15→15
-16→16
Number of
measured reflections
independent reflections
reflections with I > 2σ(I)
3085
2795
2520
3716
2047
1741
Refinement data:
R-factor
0.0377
0.0931
1.057
163
0.0369
0.1105
1.051
139
wR on F2 for all data
Goodness of fit
Number of parameters
∆ρmax, e/Å3
0.342
-0.481
-0.03(2)
0.418
-0.534
—
∆ρmin, e/Å3
Flack’s x parameter
Solution and refinement programs SIR93 [10], SHELXL97 [11] SIR93 [10], SHELXL97 [11]
CCDC deposition numbers 643598 643599
The authors express their sincere thanks to the Latvian Council of Science (grant 1771) for financial
support.
REFERENCES
1.
2.
3.
E. S. Karlov and G. S. Zaitseva, Khim. Geterotsikl Soed., 1451 (2001). [Chem. Heterocycl. Comp., 37,
1325 (2001)].
A. A. Korlyukov, E. A. Komissarov, N. V. Alekseev, K. V. Pavlov, O. V. Krivolapova, and
V. G. Lachtin, Acta Crystallogr., 62С, 303 (2006).
R. G. Kultyshev, G. K. S. Prakash, G. A. Olah, and J. W. Faller, and J. Parr, Organometallics, 23, 3184
(2004).
4.
5.
E. Lukevics, L. Ignatovich, and S. Belyakov, J. Organomet. Chem., 588, 222 (1999).
T. K. Gar, O. L. Dombrova, N. Yu. Khromova, and V. F. Mironov, Zh. Obshch. Khim., 54, 2590 (1984).
619

6.
7.
8.
9.
10.
S. Belyakov, L. Ignatovich, and E. Lukevics, J.Organomet.Chem., 577, 205 (1999).
E. Lukevics, L. Ignatovich, T. Shul'ga, and S. Belyakov, Main Group Met. Chem., 26, 67 (2003).
E. Lukevics, L. Ignatovich, and A. Kemme, Main Group Met. Chem., 25, 313 (2002).
E. Lukevics, L. Ignatovich, T. Shul'ga, and S. Belyakov, Appl. Organomet. Chem., 19, 167 (2005).
A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M. C. Burla, G. Polidori, and G. Camalli,
J. Appl. Cryst., 27, 435 (1994).
11.
G. M. Sheldrick, SHELXL97. Program for the Refinement of Crystal Structures (1997).
620