Synthesis, X-ray diffraction studies, and DFT calculations on hexacoordinated germanium derivatives: The case of germaspirobis(ocanes)

Article abstract of DOI:10.1021/ic048165m

Synthesis of the title compounds, viz. [RN(CH₂CHR′O) ₂]₂Ge (1, R = Me, R′ = H; 2, R = Me, R′ = Ph; 3, R = Ph, R′ = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH₂CHR′OH)₂ (4, R

Full text of DOI:10.1021/ic048165m

Inorg. Chem. 2005, 44, 4879−4886
Synthesis, X-ray Diffraction Studies, and DFT Calculations on
Hexacoordinated Germanium Derivatives: The Case of
Germaspirobis(ocanes)
Sergey S. Karlov,*,† Elmira Kh. Lermontova,† Maxim V. Zabalov,† Anastasia A. Selina,†
Andrei V. Churakov,‡ Judith A. K. Howard,§ Mikhail Yu. Antipin, and Galina S. Zaitseva
|
†
Chemistry Department, Moscow State UniVersity, B-234, Leninskie Gory, 119899 Moscow, Russia,
Institute of General and Inorganic Chemistry, RAS, Leninskii pr. 31, 119991 Moscow, Russia,
Department of Chemistry, UniVersity of Durham, South Road, DH1 3LE Durham, United
Kingdom, and A. N. NesmeyanoV Institute of Organoelement Compounds, RAS, VaViloVa Street 28,
119991 Moscow, Russia
Received December 28, 2004
Synthesis of the title compounds, viz. [RN(CH
Ph, R′ ) H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH
2
CHR
′
O)
2
]
2
Ge (1, R
)
Me, R′ ) H; 2, R
CHR
4
Ge is reported. Composition and structures of all novel
)
Me, R′ ) Ph; 3, R
)
2
′
OH) (4, R Me, R′ )
2
)
H; 5, R
)
Me, R′ ) Ph; 6, R
)
Ph, R′ ) H) with (AlkO)
compounds were established by 1H and C NMR spectroscopy and mass spectrometry as well as elemental
13
analysis data. The single-crystal X-ray diffraction of 2 has clearly indicated the presence of two transannular
interactions Ge
The structural data obtained from geometry optimizations by DFT calculations on 1
results. Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically
stable for all three compounds. The transition states for possible cis trans rearrangement processes in 1
were calculated. The properties of the Ge O and Ge N bonds in 1 3 were analyzed by the AIM approach. The
interactions between the Ge atom and N atoms as well as O atoms possess predominantly ionic character.
rN in the compound. N atoms are cis-orientated. The compound 3 possesses long Ge‚‚‚N distances.
−3 reproduces experimental
T
−3
−
r
−
Introduction
by the design of the atrane building block and the substituents
1
,3,4
at the metal atoms.
CH O) MX(X′) (M ) Si, Ge, Sn) (II)sclosely related
analogues of Ishave been little studied.
2
In contrast, metallocanes, RN(CH -
The structure and chemical behavior of the metallatranes,
cyclic ethers of trialkanolamines, have been extensively
studied, and compounds of elements have been reported
throughout the periodic table. Among these, metallatranes
derivatives of group 14 elements, N(CH
2
2
5
-12
It is possible
that these compounds possess even greater chemical and
structural flexibility than the metallatranes (I) since the
substituents R, X, and X′ can be varied readily along with
their influence on structures and chemical properties of
substances. Among compounds of type II, derivatives where
1
2 2 3
CH O) MX (I, M
2
-4
)
Si, Ge, Sn), are the most heavily investigated.
The
main focus of the research is the elucidation of the nature
of the transannular MrN bond, which is strongly affected
(
5) Swisher, R. G.; Holmes, R. R. Organometallics 1984, 3, 365-369.
*
Author to whom correspondence should be addressed. E-mail:
(6) Karlov, S. S.; Yakubova, E. Kh.; Gauchenova, E. V.; Selina, A. A.;
Churakov, A. V.; Howard, J. A. K.; Tyurin, D. A.; Lorberth, J.;
Zaitseva G. S. Z. Naturforsch. 2003, 58b, 1165-1170.
(7) Faur e´ , J.-L.; Gornitzka, H.; R e´ au, R.; Stalke, D.; Bertrand, G. Eur. J.
Inorg. Chem. 1999, 2295-2299.
sergej@org.chem.msu.su. Fax: +7-095-932-8846.
†
Moscow State University.
Institute of General and Inorganic Chemistry, RAS.
University of Durham.
A. N. Nesmeyanov Institute of Organoelement Compounds, RAS.
‡
§
|
(8) Kemme, A.; Bleidelis, J.; Urtane, I.; Zelchan, G.; Lukevics, E. J.
Organomet. Chem. 1980, 202, 115-121.
(
(
1) Verkade, J. G. Coord. Chem. ReV. 1994, 137, 233-295.
2) Chuit, C.; Corriu, R. J. P.; Rey e´ , C.; Young, J. C. Chem. ReV. 1993,
(9) Corey, J. Y.; Rath, N. P.; John, C. S.; Corey, E. R. J. Organomet.
Chem. 1990, 399, 221-233.
93, 1371-1448.
(
3) Pestunovich, V.; Kirpichenko, S.; Voronkov M. In The Chemistry of
Organic Silicon Compounds; Rappoport, Z., Apeloig, Y., Eds.; John
Wiley & Sons: New York, 1998; Vol. 2, Part 1, Chapter 24.
(10) Jung, O.-K.; Jeong, J. H.; Sohn, Y. S. Organometallics 1991, 10, 761-
765.
(11) Lukevics, E.; Belyakov, S.; Pudova, O. J. Organomet. Chem. 1996,
523, 41-45.
(12) Daly, J. J.; Sanz, F. J. Chem. Soc., Dalton Trans. 1974, 2051-2054.
(
4) Karlov, S. S.; Zaitseva, G. S. Chem. Heterocycl. Compd. 2001, 37,
1325-1357.
1
0.1021/ic048165m CCC: $30.25
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 13, 2005 4879
Published on Web 06/02/2005

Karlov et al.
both substituents X and X′ form one tridentate ligand
containing an additional donor group are of particular interest
due to the possible formation of an additional transannular
interaction, leading to hexacoordination at the central atom
M. The structural study of these compounds may allow new
information to be obtained for the transannular MrN bond.
established by X-ray diffraction confirming the hexacoor-
dination of the Ge atom in these compounds (2 and 3). These
data have been compared with those obtained from DFT
calculations.
Experimental Section
We expect the spirobis(ocanes), [RN(CH
Si, Ge, Sn) (C), to be the most interesting in this regard.
However, only few papers have dealt with their synthesis,
2 2 2 2
CH O) ] M (M )
General Procedures. All manipulations were performed under
a dry, oxygen-free argon atmosphere using standard Schlenk
techniques. Solvents were dried by standard methods and distilled
13-18
and the structures of only two compounds have been
determined by single-crystal X-ray diffraction.14,15,18 On the
other hand, it is well-known that hypercoordinated group 14
elements derivatives display a wide range of biological
2 2 2 2
prior to use. PhN(CH CH OH) (6) (Aldrich) and MeN(H)CH -
CH OH (Aldrich) were used as supplied. Ge(OEt) , Ge(OMe) ,29
2
4
4
30
31
MeN(CH
2
CH
2
OH)
2
(4), and MeN(CH
CH OSiMe )
2 2 3 2
were pre-
pared according to the literature. CDCl
GmbH and dried over P
1H and 13C NMR spectra were
recorded on a Varian VXR400 spectrometer (in CDCl at 295 K).
Chemical shifts in the H and 13C NMR spectra are given in ppm
relative to internal Me Si. Mass spectra (EI-MS) were recorded on
3
was obtained from Deutero
4 10
O .
activity, which makes them interesting for medicinal chem-
istry and pharmacology.3
,18,19
Thus, spirobis(ocanes) (III)
3
1
may also be potentially useful as therapeutic agents. As a
part of our program to investigate the structure and chemical
behavior of hypercoordinated germanium molecules, espe-
cially germatranes and germocanes, and to compare the
degree of strength of the transannular MrN interactions with
4
a Varian CH-7a device using electron impact ionization at 70 eV;
all assignments were made with reference to the most abundant
isotopes. Elemental analyses were carried out by the Microanalytical
Laboratory of the Chemistry Department of the Moscow State
University. In this work, the nonempirical generalized gradient
approximation (GGA) for the exchange-correlation functional of
Perdew et al. was employed.3 Calculations were performed using
the program “PRIRODA” developed by Laikov, which implements
an economical computational procedure.34 Large orbital basis sets
of contracted Gaussian-type functions of the size (5s1p):[3s1p] for
H, (11s6p2d):[4s3p2d] for C, (11s6p2d):[4s3p2d] for N, (11s6p2d):
6
,20-28
those in the derivatives of other main group elements,
we present the synthesis of three novel 1,7,9,15-tetraoxa-
,12-diaza-8-germaspiro[7.7]pentadecanes, i.e., [RN(CH
CHR′O) Ge (1-3), which are the derivatives of N-methyl-
2,33
4
2
-
2 2
]
diethanolamine (4), N-methyl-N-(2-hydroxy-2-phenylethyl)-
ethanolamine (5), and N-phenyldiethanolamine (6), respec-
tively. The motivation in our work was to study structural
changes in hypercoordinated germanium compounds arising
from the replacement of substituents at the different positions
of the ligand cage.
Compounds 1-3 were prepared via reaction of 2 equiv
of the corresponding dialkanolamine with tetraalkoxyger-
mane. The crystal structures of two of them have been
[4s3p2d] for O, and (19s16p9d):[6s5p3d] for Ge were used. The
present method has been used and has given very useful results in
21,35
the organometallic chemistry of Si, Ge, Sn, Sb, and Bi.
The
chemical bonds were analyzed by using the topological analysis
of the wave function. All critical point calculations were performed
using AIMPAC95 software package.3
6,37
N-Methyl-N-(2-hydroxy-2-phenylethyl)ethanolamine, MeN-
2 2 2
(CH CH OH)CH CH(Ph)OH (5). A mixture of N-methylethano-
(
(
(
(
(
13) Chen, D.-H.; Chiang, H.-C. Polyhedron 1995, 14, 687-691.
14) Follner, H. Monatsh. Chem. 1972, 103, 1438-1443.
15) Fiedler, R.; Follner, H. Monatsh. Chem. 1978, 108, 319-323.
16) Mehrotra, R. C.; Gupta, V. D. Indian J. Chem. 1967, 5, 643-645.
17) Kostyanovskii, R. G.; Prokof’ev, A. K.; Goldanskii, V. I.; Hrapov,
V. V.; Rochev, V. Ya. Zh. Obsh. Khim. 1968, 38, 270-273; Chem.
Abstr. 1968, 69, 92517z.
lamine (8.26 g, 0.11 mol) and styrene oxide (12.02 g, 0.10 mol)
was stirred for 24 h at room temperature. The distillation of the
reaction mixture gave a colorless oil (17.80 g, 91%; 132-136 °C,
0.02 Torr) as a mixture of 5 (95%) and MeN(CH
CHPhCH OH (5%). This mixture was used without further
purification. Analytical data for 5 are as follows. NMR spectra:
2 2
CH OH)-
2
(
(
(
18) Organic Silicon DeriVatiVes of Alkanolamines; Lukevics, E. Ya., Ed.;
1
H, δ 2.36 (s, 3H, NCH
3
), 2.52-2.66 (m, 4H, NCH
), 4.75 (dd, 1H, OCH), 7.30-
); C{ H}, δ 42.30 (NCH ), 59.25 (NCH ),
, OCH ), 70.27 (OCH), 125.86, 127.52, 128.32,
). Analytical data for MeN(CH CH OH)CHPhCH
OH are as follows. NMR spectra: H, δ 2.20 (s, 3H, NCH ), other
2
), 3.25 (br s,
Zinatne: Riga, Latvia, 1987.
19) Lukevics, E.; Germane, S.; Ignatovich, L. Appl. Organomet. Chem.
2H, OH), 3.58-3.68 (m, 2H, OCH
7
5
2
1992, 6, 543-564.
13
1
.37 (m, 5H, C
6
H
5
3
2
20) Shutov, P. L.; Karlov, S. S.; Harms, K.; Churakov, A. V.; Howard, J.
9.54, 65.94 (NCH
2
2
A. K.; Lorberth, J.; Zaitseva, G. S. Eur. J. Inorg. Chem. 2002, 2784-
2788.
142.15 (C
H
6 5
2
2
2
-
(
21) Shutov, P. L.; Karlov, S. S.; Harms, K.; Tyurin, D. A.; Churakov, A.
V.; Lorberth, J.; Zaitseva, G. S. Inorg. Chem. 2002, 41, 6147-6152.
22) Shutov, P. L.; Sorokin, D. A.; Karlov, S. S.; Harms, K.; Oprunenko,
Yu. F.; Churakov, A. V.; Antipin, M. Yu.; Zaitseva, G. S.; Lorberth,
J. Organometallics 2003, 22, 516-522.
1
3
13
1
signals overlapped with signals of protons of 5; C{ H}, δ 37.48
(
(29) Jonson, O. H.; Fritz, H. E. J. Am. Chem. Soc. 1953, 75, 718-720.
(30) Hanby, W. E.; Rydon. J. Chem. Soc. 1947, 513-519.
(31) Lukevics, E. Ya.; Libert, L. I.; Voronkov, M. G. Zh. Obshch Khim.
1969, 39, 806-809; Chem. Abstr. 1969, 71, 50058m.
(32) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. ReV. Lett. 1996, 77,
3865-3868.
(33) Ernzerhof, M.; Scuseria, G. E. J. Chem. Phys. 1999, 110, 5029-5036.
(34) Laikov, D. N. Chem. Phys. Lett. 1997, 281, 151-156.
(35) Shutov, P. L.; Karlov, S. S.; Harms, K.; Tyurin, D. A.; Sundermeyer,
J.; Lorberth, J.; Zaitseva, G. S. Eur. J. Inorg. Chem. 2004, 2498-
2503.
(36) Biegler-K o¨ nig, F. W.; Bader, R. F. W.; Tang, T.-H. J. Comput. Chem.
1982, 13, 317-328.
(37) Keith, T. A.; Laidig, K. E.; Krug, P.; Cheeseman, J. R.; Bone, R. G.
A.; Biegler-K o¨ nig, F. W.; Duke, J. A.; Tang, T.; Bader, R. F. W. The
aimpac95 programs; 1995.
(
23) Gauchenova, E. V.; Karlov, S. S.; Selina, A. A.; Chernyshova, E. S.;
Churakov, A. V.; Howard, J. A. K.; Troitsky, N. A.; Tandura, S. N.;
Lorberth, J.; Zaitseva, G. S. J. Organomet. Chem. 2003, 676, 8-21.
24) Shutov, P. L.; Karlov, S. S.; Harms, K.; Poleshchuk, O. Kh.; Lorberth,
J.; Zaitseva, G. S. Eur. J. Inorg. Chem. 2003, 1507-1510.
25) Shutov, P. L.; Karlov, S. S.; Harms, K.; Churakov, A. V.; Lorberth,
J.; Zaitseva, G. S. Eur. J. Inorg. Chem. 2004, 2123-2129.
26) Shishkov, I. F.; Khristenko, L. V.; Rudakov, F. M.; Golubinskii, A.
B.; Vilkov, L. V.; Karlov, S. S.; Zaitseva, G. S.; Samdal, S. Struct.
Chem. 2004, 15, 11-16.
(
(
(
(27) Zaitseva, G. S.; Livantsova, L. I.; Nasim, M.; Karlov, S. S.; Churakov,
A. V.; Howard, J. A. K.; Avtomonov, E. V.; Lorberth, J. Chem. Ber.
1997, 130, 739-746.
(28) Karlov, S. S.; Shutov, P. L.; Akhmedov, N. G.; Seip, M. A.; Lorberth,
J.; Zaitseva, G. S. J. Organomet. Chem. 2000, 598, 387-394.
4880 Inorganic Chemistry, Vol. 44, No. 13, 2005

Hexacoordinated Germanium DeriWatiWes
(
(
NCH
3
), 54.90 (NCH
2
), 58.92 (OCH
2
), 61.36 (OCH
2
NCH), 69.19
Table 1. Crystal Data, Data Collection, Structure Solution, and
Refinement Parameters for 2 and 3
NCH), 127.83, 128.28, 128.71 (C
6
H , signal of one carbon has
5
not been found).
,12-Dimethyl-1,7,9,15-tetraoxa-4,12-diaza-8-germaspiro[7.7]-
pentadecane, [MeN(CH CH O) Ge (1). A mixture of alkano-
lamine 4 (1.71 g, 14.4 mmol), (MeO) Ge (1.42 g, 7.2 mmol), and
benzene (10 mL) was refluxed for 2 h, and all volatiles were
removed under reduced pressure to give a white waxy solid 1 (2.21
2
3
4
formula
fw
cryst system
space group
a, Å
C22H30GeN2O4
459.07
tetragonal
P41212
11.6124(1)
11.6124(1)
15.5183(2)
C20H26GeN2O4‚C7H8
523.15
monoclinic
P21/n
17.0253(7)
18.4791(7)
17.4343(7)
118.135(1)
4836.9(3)
8
2
2
2 2
]
4
b, Å
c, Å
g, 100%). NMR spectra: 1H, δ 2.46 (s, 6H, NCH
), 2.58 (t, 8H,
3
1
2 2
NCH ), 3.71 (t, 8H, OCH ); H (223 K), δ 2.49 (br s, 6H, NCH
3
),
â, deg
V, Å3
2092.61(4)
4
13
2
{
.56-2.72 (br m, 8H, NCH
2
2
), 3.75-3.65 (br s, 8H, OCH ); C-
1
Z
H}, δ 45.46 (NCH
3
), 57.26 (NCH
2
), 58.05 (OCH
2
). Mass
-
3
d(calcd), g‚cm
abs coeff, mm
F(000)
θ range, deg
index ranges
1.457
1.495
960
1.437
1.303
2192
+
+
spectrum (EI-MS) [m/e (rel int)]: 308 (1, M ), 207 (22, M
-
-1
OCH
H, 7.23; N, 9.13. Found: C, 39.48; H, 7.51; N, 9.18.
,12-Dimethyl-2,10-diphenyl-1,7,9,15-tetraoxa-4,12-diaza-8-
germaspiro[7.7] pentadecane, [MeN(CH CH O)(CH CHPhO)] Ge
2). A mixture of alkanolamine 5 (1.80 g, 9.2 mmol), (EtO) Ge
1.17 g, 4.6 mmol), and benzene (15 mL) was refluxed for 50 h,
2
CH
2
- 2OCH
2
). Anal. Calcd for C10
H22GeN O
2 4
: C, 39.14;
2.19-27.99
1.38-28.00
-22 e h e 9
-24 e k e 23
-15 e l e 23
27 669
-15 e h e 13
4
-
-
15 351
2540
15 e k e 13
19 e l e 20
2
2
2
2
(
4
reflcns collcd
indpdt reflcns
Rint
(
11 658
0.0333
0.0418
2540/192
1.068
and all volatiles were removed under reduced pressure. The residue
was recrystallyzed from toluene mixture to give colorless micro-
crystals of 2 (1.75 g, 83%) as a mixture of three diastereomers.
data/param
11 658/885
0.950
GOOF on F2
R1 [I > 2σ(I)]
wR2 (all data)
0.0246
0.0570
0.0424
0.1109
NMR spectra: 1H, δ 2.56, 2.58, 2.59 (s, 6H, NCH
m, 8H, NCH ), 3.78-3.90 (m, 4H, OCH
OCH), 7.09-7.22, 7.31-7.35 (m, 10H, C
broad, 3NCH ), 58.03, 58.22, 58.26, 59.10, 59.16, 59.49 (NCH
5.20, 65.41, 65.47 (NCH CHO), 69.44, 69.52, 69.70 (OCH),
25.73, 125.92, 125.99, 126.86, 126.92, 127.05, 127.96, 127.99,
), 2.58-2.78
), 4.79-4.91 (m, 2H,
3
largest diff peak/hole (e‚Å-3) 0.323/-0.250
1.568/-0.639
(
2
2
13
1
6
5
H ); C{ H}, δ 47.73
),
(
3
2
Å). Semiempirical absorption corrections based on the measure-
ments of equivalent reflections were applied. The structures were
6
1
1
2
3
8
solved by direct methods and refined by full-matrix least squares
based on F2 with anisotropic thermal parameters for all non-
28.05, 143.07, 143.26, 143.42 (C
6
H
5
). Mass spectrum (EI-MS)
+
+
hydrogen atoms.39 All hydrogen atoms were found from difference
[m/e (rel int)]: 460 (5, M ), 354 (46, M - PhCHO), 266 (31,
+
Fourier syntheses and refined isotropically for both 2 and 3.
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publications nos.
CCDC-247115 and -247116. Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, U.K. [fax, +44-1223-336-033; E-mail, deposit@
ccdc.cam.ac.uk].
M - CH
GeN : C, 57.56; H, 6.59; N, 6.10. Found: C, 57.53; H, 6.67;
N, 6.15.
,12-Diphenyl-1,7,9,15-tetraoxa-4,12-diaza-8-germaspiro[7.7]-
pentadecane, [PhN(CH CH O) Ge (3). A mixture of alkanola-
mine 6 (0.80 g, 4.4 mmol), (EtO) Ge (0.56 g, 2.2 mmol), and
2
PhCHO - CH
2
CH
2
O - OCH
2 30
). Anal. Calcd for C22H -
2 4
O
4
2
2
2 2
]
4
toluene (20 mL) was refluxed for 50 h. The resulting solution was
reduced in volume to 4 mL and stored at -18 °C to give colorless
microcrystals of 3 (0.42 g, 44%). NMR spectra: 1H, δ 3.38 (t, 8H,
NCH
2
1
), 3.89 (t, 8H, OCH
2
), 6.89-6.94, 7.28-7.32 (m, 10H, C
), 62.82 (OCH ), 115.52, 119.30, 128.70,
). Mass spectrum (EI-MS) [m/e (rel int)]: 432 (5, M ).
Anal. Calcd for C20 : C, 55.74; H, 6.08; N, 6.50.
Found: C, 55.40; H, 5.92; N, 6.36.
MeN(CH CH O) Ge(OH) (7). Water (3 mL) was added to a
stirred solution of the compound 1 (2.00 g, 6.5 mmol) in toluene
10 mL) at room temperature. The reaction mixture was stirred at
6
H
5
);
Results and Discussion
13
C{ H}, δ 56.29 (NCH
49.86 (C
2
2
Synthesis. According to the literature, only two of
compounds III (M ) Ge) were synthesized so far, [HN-
+
1
6 5
H
2 4
H26GeN O
(
CH
tural information was reported. These compounds have
been synthesized via reaction of GeO or HN(CH CHR′O) Ge-
(OH) with the corresponding dialkanolamine. The treatment
2 2 2 2 2 2 2
CH O) ] Ge and [HN(CH CHMeO) ] Ge, but no struc-
1
3
2
2
2
2
2
2
2
(
2
1
3
room temperature during 72 h, and all volatiles were removed under
reduced pressure. The residue was recrystallized from the mixture
of GeO with 4 did not lead to the expected 1. Moreover,
the authors have suggested the impossibility of the synthesis
of derivatives with electron-donating groups at the nitrogen
atoms as “the germanium center will be too electron-rich
and become unstable”. Two closely related compounds
where the hexacoordination of the Ge atom is possible,
2
of methanol/acetone (1:3) to give 7 (1.30 g, 89%). NMR spectra:
1
H, δ 2.58 (s, 3H, NCH
3
), 2.65-2.71 (m, 4H, NCH
2
), 3.75-3.79,
3
.85-3.90 (m, 4H, OCH
2
), signals of OH groups have not been
1
3
13
1
found in the spectrum; C{ H}, δ 44.59 (NCH
8.10 (OCH ).
Attempted Synthesis of 1 via MeN(CH
mixture of MeN(CH CH OSiMe (10.54 g, 0.04 mol) and GeCl
4.29 g, 0.02 mol) in CHCl solution (15 mL) was refluxed for 9
3
), 55.82 (NCH
2
),
5
2
[S(CH
2 2 2 2 2 2 2 2
CH S) ] Ge and [O(CH CH S) ] Ge, have been stud-
2
2 3 2
CH OSiMe ) . A
ied by X-ray diffraction, but the Ge atom in the compounds
2
2
3
)
2
4
40
was found to be tetracoordinated. In addition, the examples
of structural investigations of neutral germanium compounds
(
3
h. No traces of 1 have been found in reaction mixture according to
NMR data.
X-ray Crystallography. Crystal data, data collection, structure
solution, and refinement parameters for compounds 2 and 3 are
given in Table 1. Both experiments were performed at 120 K on
Bruker SMART 1K diffractometer using Mo KR radiation (0.710 73
(38) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, A46, 467-473.
(
39) Sheldrick, G. M. SHELXL-97. Program for the Refinement of Crystal
Structures; University of G o¨ ttingen: G o¨ ttingen, Germany, 1997.
40) Chen, D.-H.; Chiang, H.-C.; Ueng, C.-H. Inorg. Chim. Acta 1993,
208, 99-101.
(
Inorganic Chemistry, Vol. 44, No. 13, 2005 4881

Karlov et al.
Scheme 1
Chart 1. Three Possible Isomers for Hexacoordinate 1-3
skeleton appear as a set of two pseudotriplets, forming an
1
AA′XX′ spin system (J ∼ 6 Hz). The H NMR spectrum of
2
is more complicated due to the nonequivalence of all H
atoms in one dialkanolamine moiety. It should be noted that
this compound exists as a mixture of three diastereomers.
The diastereomers differ in position of phenyl groups toward
the “ocane” skeleton. The proton resonances of the Me-N
and NCH
comparison to those in the model compounds 4 and 5 [4, δ
.23 (CH ), 2.50 (NCH ); 5, see Experimental Section].
These shifts may be explained by hexacoordination of the
2
groups in 1 and 2 are downfield shifted in
with hexacoordinated Ge atom are very rare.41 The hexaco-
2
3
2
2 2 2 2 2 2
ordinated tin derivative [HOCH CH N(CH CH O) ] Sn (ac-
cording to crystallographic data) has been obtained from the
4
2
Ge atoms in 1 and 2 in CDCl
downfield shift of the NCH group signal in the H NMR
spectrum of 3 was observed in comparison with that for
model alkanolamine 6 [6, δ 3.41 (NCH )]; i.e., the transan-
solution) are expect-
3
solutions. In contrast, no
reaction of SnCl
stannaspirobis(ocane), [CH
4
with triethanolamine,1
4,15
while another
1
2
3
N(CH CH O) ] Sn, has been
2
2
2 2
prepared by transalkoxylation reaction between 4 and adduct
Me NH‚Sn(OMe) . The authors have found from M o¨ ssbauer
spectroscopy data that the tin atom is hexacoordinated in
2
2
4
nular interactions GerN in 3 (CDCl
edly weaker than those in 1 and 2.
3
17
[
CH
several silaspirobis(ocanes) are formed in reactions of Si-
OAlk) with dialkanolamines, but yields have not been
3 2 2 2 2
N(CH CH O) ] Sn. Lukevics et al. have reported that
In the 13C NMR spectra of 1-3 the signals of the carbon
atoms of the “ocane” skeleton have the expected values.42
There are three different signals for the C atoms of compound
(
4
reported. The authors suggested the weakening of SirN
1
, six signals for those of 3, and 25 signals for the three
interaction in silaspirobis(ocanes) in comparison with that
diastereomers of 2 (27 ) 9 × 3 required peaks). The
hexacoordinate compounds 1-3 may exist as three possible
isomers, e.g., cis- and trans-isomers as shown in Chart 1,
but it should be noted that in the trans- and cis-isomers of 1
and 3, two dialkanolamine groups are equivalent. Thus, in
theory it is impossible to define what kind of isomer exists
1
8
in “usual” silocanes (B) from mass-spectrometry data.
We have also used this reaction for the syntheses of
spirobis(ocanes) 1-3. Dialkanolamines 4-6 react in reflux-
ing toluene or benzene with Ge(OAlk) (Alk ) Me or Et)
4
to give the corresponding spirobis(ocanes) 1-3, which were
isolated in high or moderate yields (Scheme 1). The
substances are very moisture sensitive. The reaction of
controlled hydrolysis of 1 led to dihydroxygermocane 7 with
high yield. Dialkanolamine 5 has been prepared by the
3
in CDCl solution, but we can conclude that only one isomer
is present for both compounds under these conditions. The
1
conclusion was supported by H NMR data of 1 at -50 °C.
1
Little change in the H NMR spectrum of 1 at -50 °C was
treatment of MeN(H)CH
product was a mixture of the expected 5 (95%) and MeN-
CHPhCH OH)CH CH OH (5%) and was used in the next
2 2
CH OH with styrene oxide. The
found in comparison to that at 23 °C; only a partial
broadening of signals was detected.
(
2
2
2
Although different sets of signals should be present in the
C NMR spectrum of the trans- and cis-isomers for
reaction without further purification. We have also tested
another approach to the spirobis(ocane) 1. Recently, we have
1
3
compound 2, it is very difficult to determine unambiguously
the type of isomer in this case due to the presence of three
diastereomers in solution.
reported the reaction of GeHal
of MeN(CH CH OSiMe readily led to the dihaloger-
mocanes MeN(CH CH O)
to prepare 1 via reaction of GeCl
CH OSiMe failed.
The composition and structures of 1-3 and 7 were
4
(Hal ) Cl, Br) with 1 equiv
2
2
3 2
)
6
2
2
2
GeHal
2
. However, our attempts
X-ray Studies. To the best of our knowledge compounds
4
with 2 equiv of MeN(CH -
2
2
and 3 are the first derivatives of germanium containing
two dialkanolamine moieties that have been structurally
characterized. To our knowledge only [PhN(CH CH O)
Si [Si atom is tetracoordinated; Si-N distances are 3.16-
(1)-3.345(9) Å for two independent molecules] and [HOCH
CH N(CH CH O) Sn [two modifications, Sn atom is
hexacoordinated; the Sn-N distances are 2.33(1)-2.38(1)
2
3 2
)
1
13
2
2
2 2
] -
established by H and C NMR spectroscopy, mass spec-
1
8
trometry and elemental analysis data.
1
13
2
-
NMR Studies. H and C NMR spectra are in accord
1
2
2
2
2 2
]
with the suggested structures. In the H NMR spectra of 1
and 3 the signals of the methylene protons of the “ocane”
14,15
Å]
have been crystallographically studied among spirobis-
(
41) Baukov, Yu. I.; Tandura S. N. In The Chemistry of Organic
Germanium, Tin and Lead Compounds; Rappoport, Z., Ed.; John Wiley
(42) Tandura, S. N.; Voronkov, M. G.; Alekseev, N. V. Top. Curr. Chem.
1986, 131, 99-189.
&
Sons: New York, 2002; Vol. 2, Chapter 16.
4882 Inorganic Chemistry, Vol. 44, No. 13, 2005

Hexacoordinated Germanium DeriWatiWes
Table 2. Selected Bond Lengths (Å) and Angles (deg)a
2
3ab
3bb
Ge(1)-N(1)
2.307(2)
Ge(1)-N(1)
Ge(1)-N(2)
Ge(1)-O(11)
Ge(1)-O(12)
Ge(1)-O(21)
Ge(1)-O(22)
3.016(2)
2.795(2)
1.761(2)
1.753(2)
1.744(2)
1.755(2)
Ge(2)-N(3)
Ge(2)-N(4)
Ge(2)-O(31)
Ge(2)-O(32)
Ge(2)-O(41)
Ge(2)-O(42)
3.055(2)
2.779(2)
1.761(2)
1.756(2)
1.749(2)
1.753(2)
Ge(1)-O(1)
Ge(1)-O(2)
1.821(1)
1.834(1)
intraligand (cis)
O-Ge-O
O(1)-Ge(1)-O(2)
O(1)-Ge(1)-N(1)
O(2)-Ge(1)-N(1)
interligand (cis)
O(1)-Ge(1)-O(1)
O(1)-Ge(1)-O(2)
O(2)-Ge(1)-N(1)
N(1)-Ge(1)-N(1)
103.56(6)
81.79(6)
80.26(6)
O(21)-Ge(1)-O(12)
O(21)-Ge(1)-O(22)
O(12)-Ge(1)-O(22)
O(21)-Ge(1)-O(11)
O(12)-Ge(1)-O(11)
O(22)-Ge(1)-O(11)
O-Ge-O(av)
124.19(8)
112.10(8)
106.16(7)
101.78(7)
109.72(7)
100.28(8)
109.04
O(41)-Ge(2)-O(42)
O(41)-Ge(2)-O(32)
O(42)-Ge(2)-O(32)
O(41)-Ge(2)-O(31)
O(42)-Ge(2)-O(31)
O(32)-Ge(2)-O(31)
O-Ge-O (av)
113.52(8)
122.40(8)
107.01(8)
101.08(7)
99.90(8)
110.47(7)
109.06
#
#
#
#
1
1
1
1
92.25(9)
93.99(6)
84.40(6)
105.06(9)
cis-angle (av)
91.62
O-Ge-N (trans)
interligand (trans)
O(1)-Ge(1)-N(1)
O(2)-Ge(1)-O(2)
O(11)-Ge(1)-N(2)
O(22)-Ge(1)-N(1)
172.23(7)
165.37(7)
O(31)-Ge(2)-N(4)
O(42)-Ge(2)-N(3)
171.71(6)
162.59(7)
#
#
1
1
170.44(6)
154.67(9)
∆
Nc
0.468(2)
∆N(1)c
0.207(3)
0.263(2)
∆N(3)c
∆N(4)c
0.176(2)
0.271(2)
∆
N(2)c
a
Symmetry transformations used to generate equivalent atoms: (#1) y, x, -z. b 3a,b are two crystallographically independent molecules of 3. c ∆N
denotes the deviation of nitrogen atom from the plane of three neighboring carbon atoms.
Figure 2. Molecular structure of 3. One independent molecule is presented.
Hydrogen atoms are omitted for clarity.
Figure 1. Molecular structure of 2. Hydrogen atoms are omitted for clarity.
compound 2 represents a distorted octahedral geometry with
N(1) and N(1A) atoms in cis-orientation. The O-Ge-N
angles [except O(1)-Ge(1)-N(1A) and O(1A)-Ge(1)-
N(1), 170.44(6)°] and O-Ge-O angles [except O(2)-Ge-
(
ocanes) of the 14 group elements. Analysis of the Cambridge
43
Structural Database (July 2004) shows that only five
structures with O GeN structural fragment have been
documented. All of them contain ethylenediaminetetraacetic
acid moiety, and it is characteristic that the Ge-N contacts
are very short due to the bonding of the Ge atom with
carboxylate groups.
The molecular structures of 2 and 3 (one independent
molecule) are shown in Figures 1 and 2. Table 2 lists selected
geometrical parameters for these compounds. The molecules
of 2 lie on a crystallographic 2-fold axis. In the structure of
4
2
(
(
1)-O(2A), 154.67(9)°] range between 80.26(6) and 105.06-
9)°. Previously studied [HOCH CH N(CH CH O) Sn also
In contrast, trans-orientation of
intermolecular donor molecules is usual for MX ‚2D (M )
Si, Ge, Sn; D ) external donor) except some cases with
special steric requirements of donor molecule, such as SiF
2
2
2
2
2 2
]
14,15
possesses cis-geometry.
4
41
4
‚
44
2
,2′-bipy where the cis-structure realizes. The GerN bonds
[
2.307(2) Å] in 2 are much longer than usual covalent Ge-N
3
, the asymmetric unit contains two independent molecules
22
bonds (1.80-1.90 Å). At the same time this value is close
to those previously found for GerN transannular bonds in
of the germocane and two independent solvate toluene
molecules. The coordination polyhedron of Ge atom in
(
44) Adley, A. D.; Bird, P. H.; Fraser, A. R.; Onyszchuk, M. Inorg. Chem.
(43) Allen, F. H. Acta Crystallogr., Sect. B 2002, B58, 380-388.
1972, 11, 1402-1409.
Inorganic Chemistry, Vol. 44, No. 13, 2005 4883

Karlov et al.
molecules with pentacoordinated Ge atom like germatranes
and germocanes which also are based on alkanolamine
and 124.19(8)°. The Ge-O distances [1.744(2)-1.761(2) Å]
are shorter than those in 2 and are comparable with those
moiety. For example, in germatranes with the NfGeO3-
O
found for closely related Ge(O-i-Pr)
confirms the absence of the considerable donation of the
electron density from the PhN group on the GeO fragment
[1.745(1) Å].46 It
4
fragment the GerN bond distance lies within 2.105-2.156
4
Å. The GerN bond length in HN(CH
2
CH
equals 2.123(4) Å. On the other hand, the GerN distance
in a germocane with two donor substituents, MeN(CH
2
O)
2
Ge(OH)
2
4
45
as it was found from NMR data (vide supra). However, the
Ge-N distances [2.779(2)-3.055(2) Å] are significantly
shorter than the sum of the van der Waals radii of the
germanium and the nitrogen (3.72 Å) and are comparable
with the lengths of GerN weak secondary interactions found
2
-
1
1
2 2 2
CH O) Ge(2-thienyl) , is substantially longer [2.446(8) Å].
Thus, the electron-donor properties of the Me group in 2
lead to the formation of two sufficiently strong transannular
GerN bonds.
2 2 3 3
in the structures of azagermatranes N[(CH CH N(SiMe )] -
22
Ge-X [2.743(2) Å, X ) n-Bu; 2.766(2) Å, X ) Ph]. As
well, N atoms in 3 are slightly shifted toward the Ge atom
by 0.18-0.27 Å. Consequently, the germanium atom in 3
can be regarded as [4 + 2]-coordinated. If we consider the
coordination polyhedron of the Ge atom as a strongly
distorted octahedron, N atoms will occupy cis-positions. It
The presence of nitrogen atoms [N(1) and N(1A)] in trans-
positions to O(1) and O(1A) effects very little change in the
length of Ge-O(1) and Ge-O(1A) bonds (1.821(1) Å) in
comparison to the Ge-O(2) and Ge-O(2A) bonds [1.834-
(1) Å]. However, the Ge-O bonds in 2 are longer than those
in Ge(O-i-Pr) , [1.745(1) Å], which is the only tetraalkox-
4
46
4
should be noted that the GeO fragment is more attractive
ygermane studied crystallographically. The elongation
results from additional electron density donation from two
for electron donation from the PhN group than SiO
The SirN distances in closely related [PhN(CH
4
moiety.18
CH O)
2
2
2 2
] -
MeN groups on the GeO
Ge-O bond lengths in 2 with those in closely related MeN-
CH CH O) Ge(-OCH CH O-) with a pentacoordinated
4
fragment. Comparison of the
Si range between 3.16(1) and 3.345(9) Å (two independent
molecules), and distortions of tetrahedron (coordination
polyhedron of the Si atom) are noticeably smaller (O-Si-O
angles: 106.9-114.4°). The approximate equality of the
(
2
2
2
2
2
germanium atom shows that the coordination polyhedron of
the Ge atom in the latter compound represents a distorted
18
47
Si-O bond lengths in [PhN(CH CH O) ] Si (1.61-1.62 Å)
trigonal bipyramid. This compound contains two different
2
2
2 2
with those in closely related silicon tetraalkoxides [Si(O-
types of Ge-O bonds: three equatorial bonds [1.776(6)-
4 4
i-Pr) 1.615(1) Å, Si(O-Menthoxy)
1.615(5)-1.624(5) Å]4
9,50
1.795(6) Å] and one axial bond [1.808(6) Å] which are
is an additional confirmation of the appropriateness of the
assertion about the weakness or absence of a transannular
situated on the opposite side to the N atom and is slightly
longer than the three others. The GerN distance in the
compound is quite short (2.159(7) Å).47 However, all four
Ge-O bonds are noticeably shorter than those found in 2.
Thus, we can note a large influence of two internal donor
interaction in [PhN(CH CH O) ] M, where M ) Si and Ge.
2
2
2 2
The eight-membered ring in 3 has a crown conformation like
that in previously studied MeN(CH CH O) Ge(2-thienyl)
2
2
2
2
,
1
1
a germocane with a weak GerN interaction. Thus, the
variation of the substituents at nitrogen atoms in spirobis-
(germocanes) easily leads to a decrease or increase of the
effective charge on the Ge atom.
groups on the GeO
4
fragment in 2 in comparison with the
2
CH O) -
same influence of the one MeN group in MeN(CH
2
2
O-).47
Ge(-OCH CH
2 2
The coordination environment of the both N atoms in
compound 2 is approximately tetrahedral, and the Ge-N-C
and C-N-C angles range between 102.1(1) and 118.1(1)°.
The nitrogen atoms are displaced by 0.47 Å from the plane
defined by three carbon atoms toward the Ge atom. The
conformation of the eight-membered rings -Ge-O-C-C-
DFT Calculations. As shown above hexacoordinate
germanium derivatives of dialkanolamines may exist as three
different isomers (see Chart 1). One can expect that these
compounds may even possess a structure with a penta- or
tetracoordinated Ge atom. To determine the structures of all
possible compounds discussed above and to estimate their
comparative stability, we have carried out DFT calculations
on these isomers up to the PBE level of theory. The most
important calculated geometry parameters of the compounds,
relative energies, as well as topological properties of GerN
and Ge-O bonds, are listed in Tables 3-5. The possible
calculated structures of 1 are presented in Figures 3-6. There
is a satisfactory agreement between main geometry param-
eters of cis-2 and cis-3 for the solid phase (crystal structures)
and for the free molecules (calculation data). However, the
calculated structure of cis-2 in contrast to the solid-state data
possesses two different GerN bonds. The explanation of
this disagreement may consist in the weakness of the
N-C-C-O- in 2 may be regarded as a boat-chair, similar
6
to that recently found for MeN(CH
2
CH
2
O)
2
GeBr
2
, while
previously studied spirogermocanes, such as n-BuN(CH
CH O) Ge[CH CH C(O)O-] and MeN(CH CH O) Ge(-
OCH CH O-) exhibit boat-boat conformation.
2
-
2
2
2
2
2
2
2
47,48
2
2
In contrast to what is found for 2, the primary coordination
environment of the Ge atom in 3 is formed by four covalent
bonded oxygen atoms and may be treated as a distorted
tetrahedron. The O-Ge-O angles range between 99.90(8)
(
(
(
(
45) Chiang, H.-C.; Lin, S.-M.; Ueng, C.-H. Acta Crystallogr., Sect. A 1992,
C48, 991-993.
46) Mitzel, N. W.; Vojinovic, K. J. Chem. Soc., Dalton Trans. 2002,
2341-2343.
47) Gurkova, S. N.; Gusev, A. I.; Alekseev, N. V.; Gar, T. K.; Viktorov,
N. A. Zh. Strukt. Khim. 1990, 31 (5), 158-160.
(49) Beckmann, J.; Dakternieks, D.; Tiekink, E. R. T. J. Organomet. Chem.
2002, 648, 188-192.
(50) Mitzel, N. W.; Blake, A. J.; Rankin D. W. H. J. Am. Chem. Soc. 1997,
119, 4143-4148.
48) Gurkova, S. N.; Gusev, A. I.; Alekseev, N. V.; Gar, T. K.; Dombrova,
O. A. Zh. Strukt. Khim. 1985, 26 (5), 185-188; Chem. Abstr. 1986,
104, 59743p.
4884 Inorganic Chemistry, Vol. 44, No. 13, 2005

Hexacoordinated Germanium DeriWatiWes
Figure 3. DFT-calculated structures of cis-1 and trans-A-1 as well as a structure of a transition state (TS1). Hydrogen atoms are omitted for clarity.
Table 4. Relative Energies (kcal‚mol- ) of All Calculated Isomers of
1
Table 3. Calculated Main Geometrical Parameters and the GerN and
Ge-O Bond Properties for Hexacoordinated Cis- and Trans-Isomers as
Well as Tetra- and Pentacoordinated Species of 1-3 and for TSs
-
1
1-3 as Well as Calculated Activation Barrier (kcal‚mol ) of the
Rearengements trans-A f cis-A and cis-A f trans-A
GerN, Å
Ge-O, Å
1
2
3
a
cis-1
2.627
1.820-1.835
1.900-1.910
1.868-1.914
1.805-1.831
cis-
trans-A-
trans-B-
0
0
0
a
trans-A-1
trans-B-1
penta-1
2.122
3.883
8.753
0.863
5.102a
6.220
14.821
9.804
a
2.185
2.380
4
.110
3.986
2.355
penta-
tetra-
Eact(trans-A- f cis-A)
Eact(cis-A- f trans-A-)
7.565
21.468
12.129
16.012
7.515
b
b, c
6.514
21.335
a
tetra-1
cis-2
1.779-1.794
1.822-1.850
23.042
12.511
13.374
2
.774
2.118
2.148
a
trans-A-2
trans-B-2
1.900-1.907
1.872-1.933
a
b
Two different structures were found due to different positions of phenyl
groups. b No stable compounds were found for this structure type. trans-
B-3 isomer may be considered as tetra-3.
c
2
.155
2.147
.153
2.341
.102
3.969
.975
3.007
.025
trans-B-2b
1.876-1.926
1.808-1.832
1.778-1.794
1.794-1.799
2
Table 5. Calculated GerN and Ge-O Bond Properties for
Cis-Isomers of 1-3
penta-2
tetra-2
cis-3
4
GerN
Ge-O
3
2
2
F(r), au ∇ λ(r), au |λ1|/λ3
cis-1 0.031
F(r), au
∇ F(r), au
|λ1|/λ3
3
0.058
0.048
0.086
0.035
0.235 0.126-0.130 0.419-0.456 0.237-0.241
0.209 0.121-0.129 0.398-0.458 0.235-0.241
0.274
a
a
a
trans-A-3
trans-B-3
TS-1
2.237
3.324
2.503
2.486
1.872-1.909
1.778-1.799
1.847-1.871
1.845-1.870
cis-2 0.023
0.051
cis-3 0.014
0.197 0.137
0.494-0.510 0.233-0.235
TS-2
2
.544
2.445
.618
-1
(
6.5-12.1 kcal mol ). It should be noted that these reactions
proceed without cleavage of GerN bonds.
TS-3
1.839-1.873
2
a
Two identical Ge-N distances were found in this compound. b Two
Besides the structures with the hexacoordinated Ge atom
for 1-3 we have also detected two other local minima for 1
and 2 on the potential energy surface. These structures
correspond to the derivatives of the pentacoordinated Ge
atom (penta-1, penta-2, Figure 5) and the tetracoordinated
Ge atom (tetra-1, tetra-2, Figure 6). Their main geometry
and energy parameters are listed in Tables 3 and 4. The
coordination polyhedron of the Ge atom in penta-1 and
penta-2 represents a distorted trigonal bypyramid with the
N atom and one O atom in apical positions while three other
O atoms occupy equatorial sites. The coordination environ-
ment of the Ge atoms in tetra-1 and tetra-2 is formed by
four O atoms and may be treated as a distorted tetrahedron.
The isomers with penta- and tetracoordinated Ge atoms are
less stable than the structures with hexacoordinated Ge atom
discussed above. The considerable contraction of the Ge-O
bonds in the range from six- to four-coordinated germanium
derivatives should be pointed out; it corresponds to experi-
different structures were found due to different positions of phenyl groups.
transannular bond in hexacoordinated compounds 1-3 and
in the absence of high symmetry in compound 2. The latter
leads to the possibility of the existence of different confor-
mations as well as diastereomers for 2 with similar energies
but different geometries.
We have found that the most stable isomer for 1-3 in the
gas phase is the cis-isomer. However, the calculated relative
energies of both possible types of trans-structures of 1-3
Table 3) are higher than those for the cis-isomers, but the
difference is not that large.
We have found the transition state geometry (TS) of cis-A
T trans-A rearrangement process (Figure 3, Tables 3 and
). The computed barrier of the gas-phase interconversion
(
4
-
1
of cis-A into trans-A is low (13.4-21.3 kcal mol ), and
the analogous barrier for the reverse process is even lower
Inorganic Chemistry, Vol. 44, No. 13, 2005 4885

Karlov et al.
On the basis of the theory of “atoms in molecules”
5
1
(
AIM), we have analyzed properties of the Ge-O and
GerN bonds in cis-1-3. We have found all anticipated
BCPs in the bonding regions. According to Bader’s theory,
a low value of the electron density [F(rbcp)] and the positive
2
value of its Laplacian ∇ [F(rbcp)] are the signs of closed-
shell interactions (ionic bonds), while shared interactions
(such as polar covalent bonds) are characterized by large
value of F(rbcp) and a negative value of the Laplacian of
Figure 4. DFT-calculated structure of trans-B-1. Hydrogen atoms are
omitted for clarity.
2
∇
F(rbcp). Additionally, the ratio |λ1|/λ3 should be below 1
for ionic bonds. Very recently, Stalke and co-workers have
analyzed the closely related system of hexacoordinated
5
2
silicon, [Me
2
2 2
N-NdC(Ph)-O] SiF , and have found that
all bonds around the Si atom in the compound possess the
dominating ionic character. Our results listed in Table 5
unambiguously testify to the ionic nature of all six bonds
around Ge atom in cis-isomers of 1-3.
Conclusion. We have found that tetraalkoxygermanes
react with dialkanolamines 4-6 leading to the formation of
the corresponding spirobis(ocanes) [RN(CH
2 2 2
CHR′O) ] Ge
(
1-3). The nature of the substituent R strongly affects the
Figure 5. DFT-calculated structure of penta-1. Hydrogen atoms are omitted
for clarity.
transannular GerN distance. According to DFT calculations
spirobis(ocanes) may possess four-, five-, and six-coordinated
Ge atoms. The derivatives with octahedrally hexacoordinated
Ge atoms with the N atoms occuping cis-positions are
thermodynamically the most stable.
Acknowledgment. We thank Prof. Dr. A. S. Peregudov
and Dr. P. V. Petrovskii for their help in NMR studies. We
thank Dr. D. N. Laikov for placing at our disposal the
program “PRIRODA”. We also thank the Research Comput-
ing Center of the Moscow State University for computational
time. A.V.C. is grateful for the grant of The President of
the Russian Federation for Young Scientists (MK-3697.2004.3)
and Russian Science Support Foundation.
Figure 6. DFT-calculated structure of tetra-1. Hydrogen atoms are omitted
for clarity.
mental data (see X-ray discussion). Also, the DFT calcula-
tions have predicted that GerN distances are noticeably
shorter and corresponding Ge-O bonds are longer in trans-
isomers in comparison with those in cis-derivatives.
To our knowledge, these are the first cases in “atrane”
and “ocane” chemistry where stable structures with and
without transannular interaction were found for the same
compound by quantum chemical methods. Of interest,
compound 3 does not have stable isomers with penta- and
tetracoordinated Ge atoms.
Supporting Information Available: X-ray crystallographic
files, in CIF format, for the structures of 2 and 3 as well as
calculation details. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC048165M
(51) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; Oxford
University Press: New York, 1990.
52) Kocher, N.; Henn, J.; Gostevskii, B.; Kost, D.; Kalikhman, I.; Engels,
(
B.; Stalke, D. J. Am. Chem. Soc. 2004, 126, 5563-5568.
4886 Inorganic Chemistry, Vol. 44, No. 13, 2005