Synthesis, structure, and reactivity of germanium-containing derivatives of substituted diethanolamines

Article abstract of DOI:10.1134/S0036023609020077

The reaction of dialkanolamines RN(CH₂CH₂O) (CHR'CHR'OH) (R = Me, Ph, PhCH₂; R' = H, Ph) with tetraethoxygermane gives either 2,2-diethoxy-1,3,6,2-dioxazagermocanes RN(CH₂CH ₂O)(CHR'CHR'O)Ge(OEt)

Full text of DOI:10.1134/S0036023609020077

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 2, pp. 211–218. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © E.Kh. Lermontova, A.V. Churakov, M. Quan, Yu.F. Oprunenko, S.S. Karlov, G.S. Zaitseva, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009,
Vol. 54, No. 2, pp. 245–253.
COORDINATION
COMPOUNDS
Synthesis, Structure, and Reactivity of Germanium-Containing
Derivatives of Substituted Diethanolamines
E. Kh. Lermontovaa, A. V. Churakova, M. Quanb, Yu. F. Oprunenkob, S. S. Karlovb,
and G. S. Zaitsevab
aKurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
bMoscow State University, Moscow, 119991 Russia
Received December 3, 2007
Abstract—The reaction of dialkanolamines RN(CH2CH2O)(CHR'CHR'OH) (R = Me, Ph, PhCH2; R' = H, Ph) with
tetraethoxygermane gives either 2,2-diethoxy-1,3,6,2-dioxazagermocanes RN(CH2CH2O)(CHR’CHR’O)Ge(OEt)2
or 1,7,9,15-tetraoxa-4,12-diaza-8-germaspiro[7.7]pentadecanes [RN(CH2CH2O) (CHR'CHR'O)]2Ge depending on
the reactant ratio. The chemical behavior of the obtained compounds in substitution reactions at germanium was stud-
ied. The product structure was confirmed by elemental analysis data and 1H, 13C, and 19F NMR spectroscopy. The
cyclotrigermanoxane [MeN(CH2CH2O)2GeO]3 was studied by X-ray diffraction.
DOI: 10.1134/S0036023609020077
The interest in germanium derivatives is dictated by tives [2]. Closely related 1,3,6,2-dioxazagermocanes B,
the extensive industrial use of germanium compounds,
in particular, for the design of electronic instruments.
Therefore, synthesis and study of previously unknown
germanium compounds is important. In recent years,
the attention of researchers has been largely concen-
trated on compounds in which the germanium atom has
a nonclassical valence other than four. The molecules
containing penta- and hexacoordinated germanium
atoms show a broad spectrum of biological activities
and find use even now as pharmaceutical drugs [1]. In
our opinion, such compounds may also be promising
for the design of new materials, in particular, nano-
structures.
cyclic ethers of dialkanolamines, are less known [3]. In
these derivatives, the germanium coordination sphere
has been extended through the germanium–nitrogen
intramolecular contact whose properties, in particular,
the bond strength, are determined by the environment
of the atoms forming this bond [4].As regards the mate-
rial design, 1,3,6,2-dioxazagermocanes B seem more
promising due to the presence of two substituents X at
germanium, whose variation would give rise to mole-
cules containing several ocane groups and to complex
molecular assemblies. In addition, it has been shown
previously that the length of intramolecular germa-
nium–nitrogen bond in 1,3,6,2-dioxazagermocanes,
unlike that in germatranes, varies over a broad range
Germatranes A, cyclic ethers of trialkanolamines,
are best studied hypercoordinated germanium deriva- (2.080(3)–3.182(1) Å) [3].
R'
R'
R'
R
O
N
N
R'
O
R
X
Ge
X
O
O
Ge
X
O
N
Ge
N
O
O
R
O
R'
O
Ä
B
R'
C
Various synthetic approaches to 1,3,6,2-dioxazager- mediates for the synthesis of new, more complex 1,3,6,2-
mocanes have been developed. As a result, a broad range dioxazagermocanes B having specified useful properties
of 2,2-diorganyl- (B, X = alkyl, aryl) and 2,2-dihalo- [5–8]. However, little data have been published on one
1,3,6,2-dioxazagermocanes (B, X = halogen) have been more class of useful precursors, functionally substituted
prepared. The latter compounds seem to be good inter- 1,3,6,2-dioxazagermocanes, in particular, 2,2-dialkoxy
211

212
LERMONTOVA et al.
derivatives (B, X = AlkO). Until recently, only com- kanolamine II (2.58 g, 13 mmol), and benzene (20 mL)
pounds containing dialcohol residues as ligands have was refluxed for 5 h. The volatile components were
been reported [9]. It was only in 2006 that we published removed in vacuo, and the solid residue was washed
a paper [10] where demonstrated the existence of 2,2- with ether to give 3.84 g (83%) of compound VII as a
dialkoxy-1,3,6,2-dioxazagermocanes and developed a white solid.
preparative method for their synthesis by exchange
1H NMR (CDCl3, δ, ppm): 1.22 (t, 6H, CH3); 2.51–
between 2,2-dihalo-1,3,6,2-dioxazagermocanes and tri-
2.60, 2.95–3.00 (both m, 4H, NCH2); 3.78–3.84, 4.01–
4.08 (both m, 4H, OCH2); 3.97 (br.s, 2H, CH2Ph);
7.30–7.34 (m, 5H, aromatic protons).
alkylalkoxystannanes. It is evident that further studies
along this line are required in order to develop other
approaches to previously unknown 2,2-dialkoxy-1,3,6,2-
dioxazagermocanes B, to study their structure and reac-
tivity. It also appears important to continue studies on the
chemistry of related compounds, 2,2-dihydroxy-1,3,6,2-
dioxazagermocanes and their esters (B, X = OH,
OC(O)Y), and 1,7,9,15-tetraoxa-4,12-diaza-8-ger-
maspiro[7.7]pentadecanes (type C), which are called
below germaspiro-bis-ocanes for the sake of simplicity.
We studied derivatives of five dialkanolamines (I–V)
containing N and C substituents with different electronic
and steric properties.
13C NMR (CDCl3, δ, ppm): 17.51 (CH3); 49.91,
56.92, 57.43 (OCH2, NCH2); 60.15 (CH2Ph); 128.43,
131.07, 133.33, 139.32 (aromatic carbons).
For C15H25GeNO4 anal. calcd. (wt %): C, 50.61; H,
7.08; N, 3.93.
Found (wt %): C, 49.86; H, 6.88; N, 3.52.
Reaction of dialkanolamine IV with Ge(OEt)4.
erythro-6-Methyl-4,5-diphenyl-2,2-diethoxy-1,3,6,2-
dioxazagermocane (VIII). Synthetic operations were
carried out as described for VII starting from Ge(OÖt)4
(1.1 g, 4.3 mmol) and dialkanolamine IV (1.17 g,
4.3 mmol). The volatile components were removed in
vacuo, and the residue was extracted with ether. The
ether-insoluble compound was germaspiro-bis-ocane
IX (1H NMR data, the spectra are given below) (0.34 g,
26% in relation to alkanolamine). Removal of the ether
from the filtrate gave diethoxigermocane VIII (0.59 g,
32%) as a yellow oil.
1H NMR (CDCl3, δ, ppm): 1.17–1.30 (m, 6H, CH3);
2.22 (s, 3H, NH3); 2.73–2.76, 3.26–3.33 (both m, 2H,
NCH2); 3.77 (d, 1H, NCH); 3.69–3.87, 3.94–4.08
(both m, 6H, OCH2); 5.42 (d, 1H, OCH); 7.02–7.14
(m, 10H, aromatic protons).
I: R = Me, R' = H
CH2CH2OH
II: R = PhCH2, R' = H
R N
III: R = Ph, R' = H;
CH CHOH
IV: R = Me, R' = Ph (erytho)
R' R'
V: R = Me, R' = Ph (threo)
I–V
EXPERIMENTAL
All synthetic operations were carried out under argon
using standard Schlenk glassware. The 1ç, 13ë, and 19F
NMR spectra were recorded on a Varian XR-400 spec-
trometer operating at 400, 100, and 376.4 MHz, respec-
tively; CDCl3 served as the solvent and the internal ref-
erence. The chemical shifts are referred to TMS.
6-Methyl-2,2-diethoxy-1,3,6,2-dioxazagermocane
(VI). A solution of Ge(OÖt)4 (0.77 g, 3 mmol) and dial-
kanolamine I (0.36 g, 3 mmol) in toluene (15 mL) was
refluxed for 5 h. The volatile components were removed
in vacuo, and the residual yellow oil was reevaporated
under an oil pump vacuum (0.1 mmHg) to give 0.65 g
(77%) of compound VI as a colorless glassy solid.
13C NMR (CDCl3, δ, ppm): 18.62 (CH3); 42.36
(NCH3); 58.40, 59.78, 60.65, 71.86, 73.81 (OCH2,
NCH2, NCH, OCH).
Reaction of dialkanolamine III with Ge(OEt)4 [11].
A mixture of dialkanolamine III (0.80 g, 4.4 mmol),
1ç NMR (CDCl3, δ, ppm): 1.07–1.12 (m, 6H, CH3); Ge(OÖt)4 (0.56 g, 2.2 mmol), and toluene (20 mL) was
2.44 (s, 3H, NCH3); 2.54–2.69, 2.66–2.72 (both m, 4H, refluxed for 50 h and cooled to room temperature. The vol-
atile compounds (80%) were removed in vacuo, and the
residue was collected on a filter, washed with anhydrous
ether (2 × 3 mL), and dried in vacuum (0.1 mmHg) to give
0.42 g (44%) of compound XI as a white powder. The 1H
and 13C NMR spectra were consistent with published data
[11]. The solvents were removed from the filtrate in vacuo
to give a yellow oil, which was a mixture of two com-
pounds: germaspiro-bis-ocane XI and diethoxyger-
mocane XII. The latter could not be isolated in a pure
state.
NCH2); 3.67–3.75, 3.79–3.85 (both m, 8H, OCH2).
13C NMR (CDCl3, δ, ppm): 18.77, 18.84 (CH3);
43.75 (NCH3); 55.18, 57.45 (NCH2, OCH2); 59.41,
60.23 (2OCH2CH3).
1H NMR (CDCl3, δ, ppm, 50°ë): 1.15 (t, 6H, CH3);
2.49 (s, 3H, NCH3); 2.64–2.70, (m, 4H, NCH2); 3.79
(t, 4H, OCH2), 3.90 (q, 4H, OCH2).
For C9H21GeNO4 anal. calcd. (wt %): C, 38.62; H,
7.56; N, 5.00.
1H NMR (CDCl3, δ) (for XII): 0.99 (t, 6H, CH3);
3.43 (t, 4H, NCH2); 3.69 (q, 4H, OCH2), 4.09 (t, 4H,
Found (wt %): C, 38.56; H, 7.42; N, 4.82.
6-Benzyl-2,2-diethoxy-1,3,6,2-dioxazagermocane
(VII). A mixture of Ge(Oet)4 (3.35 g, 13 mmol), dial- OCH2), 6.97–6.93 (m, aromatic protons).
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SYNTHESIS, STRUCTURE, AND REACTIVITY OF GERMANIUM-CONTAINING
213
13C NMR (CDCl3, δ, ppm) (for XII): 18.18, 56.68,
13C NMR (CDCl3, δ, ppm): 50.06, 56.81, 57.58
60.95 (NCH2); 63.27 (OCH2); 116.05, 119.90, 128.24, (OCH2, NCH2); 127.87, 128.25, 131.24, 134.12 (aro-
149.32 (aromatic carbons).
matic carbons).
erythro-4,12-Dimethyl-2,3,10,11-tetraphenyl-
1,7,9,15-tetraoxa-4,12-diaza-8-germaspiro[7,7]pen-
tadecane (IX). A mixture of dialkanolamine IV (2.6 g,
9.7 mmol), Ge(OÖt)4 (1.23 g, 4.9 mmol), and benzene
(25 mL) was refluxed for 50 h. The volatile compounds
were removed in vacuo, and the residue was recrystal-
lized from toluene to give 2.28 g (76%) of compound
For C11H17GeNO4 anal. calcd. (wt %): C, 44.06; H,
5.71; N, 4.67.
Found (wt %): C, 43.80; H, 5.58; N, 4.36.
2,2-Dihydroxy-6-methyl-1,3,6,2-dioxazagermocane
(XV). Water (3 mL) was added to a solution of ger-
maspiro-bis-ocane X (2 g, 6.5 mmol) in toluene
(25 mL). The reaction mixture was stirred for 72 h. The
volatile compounds were removed in vacuo, and the
residue was recrystallized from a methanol/acetone
mixture (1 : 3) to give 1.3 g (89%) of compound XV as
colorless crystals.
1H NMR (CDCl3, δ, ppm): 2.58 (s, 3H, NCH3);
2.65–2.71 (m, 4H, NCH2); 3.75–3.79, 3.85–3.90 (both m,
4H, OCH2).
13C NMR (CDCl3, δ, ppm): 44.59 (NCH3); 55.82
(NCH2); 58.10 (OCH2).
According to 1H and 13C NMR data, the filtrate con-
tained dialkanolamine I.
1
IX as a white powder. The H and 13C NMR spectra
exhibited signals for three diastereomers, which were
not unambiguously assigned.
1H NMR (CDCl3, δ): 2.15, 2.28, 2.33 (all s, 6H,
CH3N); 2.44–2.51, 3.33–3.48, 3.96–3.98, 4.18–4.33
(all m, 8H, CH2); 3.46, 3.72 (both d, 2H, NCH2), 5.23
(d), 5.54 (br.s), 6.03 (br.s, 2H, OCH); 6.90–7.09, 7.26–
7.34 (both m, 20H, aromatic protons).
13C NMR (CDCl3, δ, ppm): 43.31, 43.79, 45.21
(NCH3); 56.44, 57.88, 58.78 (NCH2); 60.87, 61.28
(NCH) (signal for one diastereomer was not observed);
72.53, 74.36, 75.55, 73.64, 75.36, 74.74 (OCH);
125.84, 126.06, 126.19, 126.38, 126.88, 126.95,
127.06, 127.18, 127.28, 127.36, 127.42, 127.84,
127.92, 128.09, 129.29, 130.54, 130.80, 130.91,
141.59, 141.83, 142.51 (aromatic carbons).
Cyclotrigermanoxane (XVI). A toluene solution
of germaspiro-bis-ocane X (0.1 mL) was allowed to
stand in air at room temperature for several days. This
gave crystals suitable for X-ray diffraction.
For C34H38GeN2O4 anal. calcd. (wt %): C, 66.46; H,
6.10; N, 4.52.
6-Methyl-1,3,6,2-dioxazagermocane-2,2-diyl bis(tri-
fluoroacetate) (XVIII). A solution of (CF3CO)2O
(0.54 g, 0.24 mmol) in dioxane (10 mL) was slowly
Found (wt %): C, 66.96; H, 6.00; N, 4.21.
threo-4,12-Dimethyl-2,3,10,11-tetraphenyl-1,7,9,15- added to a solution of 2,2-dichloro-6-methyl-1,3,6,2-
tetraoxa-4,12-diaza-8-germaspiro[7,7]pentadecane dioxazagermocane XVIII (0.21 g, 0.8 mmol) in diox-
(XIII) was prepared as described for X by refluxing dial- ane (10 mL). The trifluoroacetyl chloride evolved was
kanolamine V (0.4 g, 1.5 mmol), Ge(OÖt)4 (0.19 g, collected in a trap cooled to –78°ë. For complete
removal of the chloride, the reaction mixture was vig-
orously stirred for 2 h at 40°ë. The resulting solid resi-
due was washed with ether to give 0.31 g (92%) of
compound XVIII as a white powder.
1H NMR (CDCl3, δ, ppm): 3.01 (s, 3H, NCH3); 3.61
(t, 4H, CH2); 4.81 (t, 4H, CH2).
0.7 mmol), and benzene (10 mL) for 50 h. Recrystalli-
zation from toluene gave 0.38 g (89%) of compound
XIII as a white powder.
1H NMR (CDCl3, δ): 2.29 (s, 6H, CH3N); 2.41–2.51
(m, 4H, NCH2); 3.61 (d, 2H, NCH), 3.67–3.77 (m, 4H,
OCH2); 5.04 (d, 2H, OCH); 7.07–7.13, 7.19–7.26, 7.34
(all m, 20H, aromatic protons).
13C NMR (CDCl3, δ, ppm): 41.69 (CH3); 54.78,
61.67 (CH2).
For C34H38GeN2O4 anal. calcd. (wt %): C, 66.46; H,
6.10; N, 4.52.
19F NMR (CDCl3, δ, ppm): –77.39 (s, CF3).
Found (wt %): C, 66.80; H, 6.27; N, 4.58.
erythro-6-Methyl-4,5-diphenyl-2,2-difluoro-1,3,6,2-
dioxazagermocane (XIX). A solution of BF3 · Et2O
(0.05 g, 0.33 mmol) in CH3CN (7 mL) was added drop-
wise to a solution of 2,2-diethoxygermocane VIII
(0.21 g, 0.50 mmol) in CH3CN (3 mL) heated to 50°ë.
The mixture was stirred at 50°C for 8 h and the volatile
compounds were removed in vacuo. Ether (5 mL) was
added to the residue and the mixture was stirred for 2 h.
The precipitate was collected on a filter and dried in
vacuo to give compound XIX (0.14 g, 72%) as a white
6-Benzyl-2,2-dihydroxy-1,3,6,2-dioxazagermocane
(XIV). GeO2 (1.1 g, 11 mmol) was added in one portion
to a mixture of diethanolamine II (2.1 g, 11 mmol) and
water (10 mL). The mixture was refluxed for 4 h, water
was removed at a reduced pressure, and the residue was
recrystallized from a methanol/acetone mixture (1 : 3) to
give 1.7 g (56%) of compound XIV as a white powder.
1H NMR (CDCl3, δ, ppm): 2.44–2.50, 2.92–2.98
(both m, 4H, NCH2); 3.75–3.79, 3.98–4.03 (both m,
4H, OCH2); 4.13 (s, 2H, CH2Ph); 7.19–7.22, 7.29–7.31
(both m, 5H, aromatic protons).
1
solid. The H and 13C NMR spectra exhibited signals
for two diastereomers in 3 : 1 ratio.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 2 2009

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LERMONTOVA et al.
1H NMR (DMSO-d6, δ, ppm): 2.19, 2.38 (both s,
Found (wt %): C, 47.98; H, 6.37; N, 7.38.
3H, CH3N); 2.78–2.82, 3.03–3.09 (both m, 2H, NCH2);
3.52–3.61, 3.99–4.05 (both m, 2H, OCH2), 4.11, 4.12
X-ray diffraction study of compound XVI was
carried out on a Bruker SMART APEX automated dif-
(both d, 1H, NCH); 5.28, 5.58 (both d, 1H, OCH); fractometer at 120 K (MoKα radiation, λ = 0.71073 Å,
6.90–7.02, 7.06–7.09, 7.12–7.16 (all m, 10H, aromatic
protons).
graphite monochromator). The crystals of XVI
(C15H33Ge3N3O9, M = 617.21) are monoclinic, space
group ê21/Ò, a = 10.5973(12) Å, b = 18.002(2) Å, c =
13C NMR (DMSO-d6, δ, ppm): 54.93, 59.09
(NCH3); 59.85, 61.34 (NCH2); 68.81, 68.95 (OCH2); 11.8721(13) Å, β = 100.893(3)°, V = 2224.1(4) Å3,
72.53, 73.90, 76.14, 79.13 (NCH, OCH); 125.56, Z = 4, ρcalcd = 1.843 g/cm3, µ(MoKα) = 4.080 mm–1,
125.90, 127.35, 127.67, 128.00, 130.90, 139.65, 140.59
(aromatic carbons).
19F NMR (DMSO-d6, δ, ppm): –143.90 (1F), –141.87
(1F) (GeF).
For C5H11F2GeNO2 anal. calcd. (wt %): C, 26.38; H,
4.87; N, 6.15.
F(000) = 1248. The intensities of 12981 reflections (of
these, 5295 independent reflections, Rint = 0.0354) were
measured in the ω scan mode in the range 2.99° < θ <
28.00° (–13 ≤ h ≤ 13, –23 ≤ k ≤ 23, –15 ≤ l ≤ 12). The
structure was solved by direct methods (SHELX-86
[12]). All non-hydrogen atoms were refined by full-
matrix anisotropic least-squares on F2 (SHELXL-97
[13]). One of the three ocane fragments is rotationally
disordered over two positions with an occupancy ratio of
0.59/0.41. All hydrogen atoms (except for disordered
ones) were found from a difference Fourier synthesis and
refined isotropically. The hydrogen atoms of disordered
groups were placed in calculated positions and refined
using the riding model. The final R values were R1 =
0.0320 and wR2 = 0.0691 for 4271 reflections with I
> 2σ(I) and 388 refinement parameters; GOOF = 1.020,
∆ρmin/max = –0.480/0.713 e Å–3.
Found (wt %): C, 27.03; H, 4.67; N, 6.34.
Germocane XX. A solution of 2,2-dihydroxy-6-
methylgermocane XV (0.22 g, 1 mmol) and 9-hydroxy-
9H-fluorene-9-carboxylic acid (0.22 g, 1 mmol) in tol-
uene (20 mL) was refluxed for 10 h to give compound
XX (0.3 g, 72%) as a white solid.
1H NMR (C6D6, δ, ppm): 2.67 (s, 3H, NCH3); 2.92–
2.96, 3.09–3.14 (both m, 4H, CH2); 4.10–4.13 (m, 4H,
CH2); 7.14–7.16, 7.34–7.37, 7.45, 7.62 (all m, 8H, aro-
matic protons).
For C19H19GeNO5 anal. calcd. (wt %): C, 55.12; H,
4.63; N, 3.38.
RESULTS AND DISCUSSION
Found (wt %): C, 55.34; H, 4.67; N, 3.34.
2,2-Dialkoxygermocanes were synthesized for the
first time using organotin reagents [10]. Previously, the
lack of prospects in using the most obvious approach to
2,2-dialkoxygermocanes, transalkoxylation reaction,
was apparently based on publication [14] stating that
the expected products are not formed in this reaction;
rather, germaspirobis(ocane) [HN(CH2CH2O)2]2Ge
was isolated from the reaction mixture.
Reaction of 2,2-dihydroxy-6-methylgermocane
XV with menthol. A solution of 2,2-dihydroxy-6-
methylgermocane XV (0.46 g, 2 mmol) and L-menthol
(0.64 g, 4 mmol) in toluene (20 mL) was refluxed for
10 h. According to 1H NMR, no reaction took place.
4-Methyl-12-phenyl-1,7,9,15-tetraoxa-4,12-diaza-
8-germaspiro[7,7]pentadecane (XXI). A mixture of
diethanolamine III (0.32 g, 1.8 mmol), 2,2-diethoxy-6-
methylgermocane (0.50 g, 1.8 mmol), and toluene
(20 mL) was refluxed for 25 h and cooled to room tem-
perature. The volatile compounds (80%) were removed
in vacuo, and the precipitate was collected on a filter,
washed with anhydrous ether (2 × 3 mL), and dried in
vacuum (1 mmHg) to give 0.56 g (84%) of compound
XXI as a white powder.
1H NMR (CDCl3, δ): 2.48 (s, 6H, NCH3); 2.47–
2.52, 2.58–2.66 (both m, 4H, NCH2); 3.29–3.33, 3.54–
3.59 (both m, 4H, OCH2), 3.36–3.40 (dt, 4H, NCH2);
4.06, 4.10 (both t, 4H, OCH2); 6.60–6.63, 6.80–6.82,
7.13–7.25 (all m, aromatic protons).
13C NMR (CDCl3, δ, ppm): 44.19 (NCH3); 52.97,
53.27, 55.06, 57.12, 61.52, 61.97 (NCH2, OCH2);
112.84, 115.85, 128.67, 150.57 (aromatic carbons).
For C15H24GeN2O4 anal. calcd. (wt %): C, 48.83; H,
6.56; N, 7.59.
We studied the reaction of dialkanolamines I, II,
and IV with tetraethoxygermane and found that
dialkoxygermocanes are formed in satisfactory yields.
R'
R
N
CH2CH2OH
R'
Ge(OEt)4
R N
EtO Ge
O
–2EtOH
CH CHOH
O
OEt
VI–VIII
R' R'
I, II, IV
+I, VI: R = Me, R' = H; II, VII: R = PhCH2, R' = H
IV, VIII: R = Me, R' = Ph (erythro)
Previously we have shown that the reaction of
Ge(OÄlk)4 with two equivalents of amino alcohols I
and III gives germaspirobis(ocanes) (C: X, XI) [11].
Further study of this reaction carried out here has
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SYNTHESIS, STRUCTURE, AND REACTIVITY OF GERMANIUM-CONTAINING
215
shown that the reaction of Ge(OEt)4 with III yields diethoxygermocane XII as a by-product.
Ph
N
Ge(OEt)4
[PhN(CH2CH2O)2]2Ge + EtO Ge
O
2PhN(CH2CH2OH)2
III
–xEtOH
O
XI
XII
OEt
The reactions of dialkanolamines IV andVwith Ge(OÖt)4 respectively, in high yields.
in a 2 : 1 ratio give germaspirobis(ocanes) IX and XIII,
Ph
Ph
O
O
Me
CH2CH2OH
Ge(OEt)4
–4EtOH
2Me N
N
Ge
N
CH CHOH
Ph Ph
Me
O
Ph
O
Ph
IV, IX: erythro; V, XIII: threo
IX, XIII
2,2-Dihydroxy derivatives can be prepared both by
treatment of germanium dioxide with dialkanolamine
in the presence of water and by hydrolysis of ger-
maspirobis(ocanes) with excess H2O. Both approaches
were used in this study. Dihydroxy derivative XIV was
obtained in 56% yield by refluxing a mixture of dial-
kanolamine II and GeO2 in water.
O
O
Me
Me
N
H2O
N
Ge
N
HO Ge
OH
O
Me
O
O
O
X
XV
PhCH2
N
Compound XV was synthesized by the reaction of
methyldiethanolamine I with GeO2/H2O [15]. The
transformation of 2,2-dihydroxygermocanes into spiro-
cyclic derivatives or into cyclotrigermoxanes depend-
ing on the N-substituent was reported in the literature.
The addition of water to these compounds results again
in the initial 2,2-dihydroxygermocanes [16].
GeO2/H2O
PhCH2N(CH2CH2OH)2
II
HO Ge
O
O
XIV
OH
The controlled hydrolysis of germaspirobis(ocane)
X under mild conditions afforded 2,2-dihydroxy deriv-
ative XV in a high yield.
R
N
O
O
O
O
R
O
R
N
Ge
O
Ge
O
O
R
H2O
H2O
O
N
N
Ge
N
RN(CH2CH2OH)2
–H2O
N
R
HO Ge
OH
O
R
O
Ge
O
O
O
O
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 2 2009

216
LERMONTOVA et al.
We obtained the crystals of XVI (R = Me) upon
The first representative of a new class of germocanes,
long-term storage of germaspirobis(ocane) X in air 2,2-dicarboxylatogermocane, was prepared by treatment
and confirmed their structure by X-ray diffraction.
of
2,2-dichloro-6-methyl-1,3,6,2-dioxazagermocane
XVII with trifluoroacetic anhydride.
O
MeN(CH2CH2O)2Ge(OCCF3)2
XVIII
2(CF3CO)2O
2CF3C(O)Cl
MeN(CH2CH2O)2GeCl2
–
XVII
We studied the chemical properties of the compounds etherate to give trifluoro derivative [10]. In this study we
synthesized. Previously, we found that 2,2-dihydroxyger- showed that the ethoxy groups in 2,2-diethoxygermocanes
mocane XV undergoes exchange with boron trifluoride can be replaced by fluorine atoms.
Ph
Ph
Me
Me
N
N
BF3 · (OEt)2
Ph
erythro-
erythro-
Ph
–Et2O
–[EtOBF2}
F
Ge
F
O
EtO Ge
O
O
O
OEt
VIII
XIX
It was also found that germocane XV easily reacts presence of minor germaspirobis(ocane) impurities.
with 9-hydroxy-9H-fluorene-9-carboxylic acid to give The latter is also true for dihydroxy derivatives.
The 1H, 13C, and 19F NMR data of the prepared ger-
mocanes correspond to the proposed structures. A key
aspect considered during the NMR study of the product
structures in solutions is the presence or absence of
transannular interactions. For C-unsubstituted ger-
mocanes, the conclusion about the presence of transan-
nular interactions in solution was based on the down-
field shift of the proton signals of the NCH2 groups of
the ocane cage with respect to those of model com-
pounds (trimethyl silyl ethers of dialkanolamines [10]).
For C-substituted ocanes, this conclusion was based on
the existence of the compounds as diastereomer mix-
tures due to the chirality of nitrogen in these com-
pounds with a transannular bond.
dispirocyclic derivative XX.
However, the reaction of XV with two equivalents
of L-menthol does not result in the expected dimen-
thoxygermocane: after 10 h of refluxing in toluene, the
reaction mixture still contained only the starting com-
pounds according to 1H NMR data.
An important result of this study is the synthesis of
unsymmetrical germaspirobis(ocane) XXI by the reac-
tion of diethoxy derivative VI with 1 equivalent of
amino alcohol III.
Me
O
N
O
Ph
III
–2EtOH
EtO Ge
O
N
Ge
N
An NMR study of germocane VI showed the pres-
ence of two non-equivalent ethoxy groups. These is due
to the absence or difficulty of the conformation
exchange of the positions of axial and equatorial EtO
groups.
O
Me
O
OEt
VI
O
XXI
Note that, in the case of similar titanium derivatives,
no such unsymmetrical derivatives are formed, but the
reactions give mixtures of two symmetrical titanospiro-
bis(ocanes) [17]. The structure of compound XXI is
discussed in detail below.
The structures of the obtained compounds were con-
firmed by NMR spectroscopy and, in some cases, by
elemental analysis data. Note that preparation of ana-
lytically pure samples of 2,2-dialkoxy derivatives is
Me
N
EtO Ge
O
O
OEt
VI
As the temperature of recording the spectrum
hampered due to their hydrolytic instability and the increases to 50°ë, the signals of the EtO protons coa-
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 2 2009

SYNTHESIS, STRUCTURE, AND REACTIVITY OF GERMANIUM-CONTAINING
217
C(21)
C(22)
O(21)
N(2)
C(2)
C(24)
C(32)
O(32)
O(3)
C(23)
Ge(2)
C(36)
C(31)
C(33)
O(22)
O(1)
O(31)
Ge(3)
C(1)
C(34)
N(3)
Ge(1)
N(1)
O(11)
C(11)
C(13)
C(35)
C(4)
O(12)
C(14)
C(3)
C(12)
Molecular structure of compound XVI.
Key structural parameters of XVI: bond lengths (d) and bond angles (ω)
Bond
d, Å
Bond
d, Å
Ge
N
2.231(2)–2.284(2)
1.781(2)–1.795(2)
Ge–Xax
Ge–Xeq
1.794(2)–1.804(2)
1.738(2)–1.755(2)
Ge–O
Angle
ω, deg
Angle
ω, deg
NgeXax
NGeXeq
NGeO
169.68(9)–172.96(9)
85.67(9)–87.64(9)
80.90(9)–83.06(9)
117.05(9)–118.4(1)
OGeXeq
OGeXax
XaxGeXeq
CNC
114.8(1)–122.61(9)
92.55(9)–95.21(9)
100.17(9)–104.43(9)
107.4(5)–115.5(5)
101.1(3)–118.0(2)
OGeO
CNGe
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 2 2009

218
LERMONTOVA et al.
lesce; thus, the activation energy of conformation tran- deviated from the root-mean-square plane to the highest
extent. The eight-membered Ge–O–C–C–N–C–C–O
rings in XVI have a “chair–boat” conformation.
sition can be estimated as <15 kcal/mol.
Previously, the hexacoordination of germanium in
germaspiro-bis-ocane X in a CDCl3 solution and tetraco-
ordination of germanium in XI under similar conditions
were demonstrated [11]. The germaspirobis(ocanes) IX
and XIII prepared in this work also contain a hexacoor-
dinated germanium atom. Conversely, analysis of the
spectral data of unsymmetrical germaspirobis(ocane)
XXI and their comparison with the data for X and XI
(the proton chemical shifts of XXI are similar to those
for X and XI) leads to the conclusion that XXI contains
a pentacoordinated germanium atom with a strong
MeN–Ge bond. Thus, compound XXI is the first repre-
sentative of a germaspirobis(ocane) with a pentacoordi-
nated central atom.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research (project no. 06-03-33032a).
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RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 2 2009