Synthesis and molecular structure of phenyl and tolylgermatranes

Article abstract of DOI:10.1016/S0022-328X(99)00378-2

The crystals of arylgermatranes (R=H (I), 4-CH₃ (II), 3-CH₃ (III), 2-CH₃ (IV)), have been obtained to study the influence of a substituent position on coordination of the germanium atom. Compounds I-IV were prepared by the insertion of GeBr₂ into the carbon-bromine bond of the corresponding arylbromide, conversion of aryltribromogermanes to triethoxy derivatives by alcoholysis and their transalkoxylation with triethanolamine to germatranes; or by the condensation of halobenzene with GeCl₄ in the presence of copper powder followed by alcoholysis and cyclization. The crystal structure of compounds I-IV was studied via the X-ray diffraction method. The intramolecular donor-acceptor bond Ge←N in arylgermatranes (2.212-2.230 A) is longer than that in the corresponding furyl- and thienylgermatranes. Introduction of a substituent into o-position of the benzene ring decreases the N-Ge-C angle value from 177.5 to 144.2°. The quantum chemical calculations were performed to investigate structures I-IV in isolated molecules.

Full text of DOI:10.1016/S0022-328X(99)00378-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 588 (1999) 222–230
Synthesis and molecular structure of phenyl and tolylgermatranes
Edmunds Lukevics *, Luba Ignatovich, Sergey Belyakov
Lat6ian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Lat6ia
Received 11 May 1999; received in revised form 20 June 1999
Abstract
The crystals of arylgermatranes
(R=H (I), 4-CH3 (II), 3-CH3 (III), 2-CH3 (IV)), have been obtained to study the influence of a substituent position on
coordination of the germanium atom. Compounds I–IV were prepared by the insertion of GeBr2 into the carbonꢀbromine bond
of the corresponding arylbromide, conversion of aryltribromogermanes to triethoxy derivatives by alcoholysis and their
transalkoxylation with triethanolamine to germatranes; or by the condensation of halobenzene with GeCl4 in the presence of
copper powder followed by alcoholysis and cyclization. The crystal structure of compounds I–IV was studied via the X-ray
,
diffraction method. The intramolecular donor–acceptor bond Ge’N in arylgermatranes (2.212–2.230 A) is longer than that in
the corresponding furyl- and thienylgermatranes. Introduction of a substituent into o-position of the benzene ring decreases the
NꢀGeꢀC angle value from 177.5 to 144.2°. The quantum chemical calculations were performed to investigate structures I–IV in
isolated molecules. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Aryltrihalogenogermane; Germatrane; Crystal structure; MNDO calculation; Toxicity
bond distances for all germatranes are in the range
1. Introduction
,
2.011–2.29 A (Table 1). The general consensus is
that more electronegative groups R yield shorter
Organic derivatives of pentacoordinate germanium
have attracted a great deal of interest in the recent
years. Germatranes
tramolecular Ge’N bond are the most intensively
studied class of such compounds. The analysis of
the Cambridge Crystallographic Data Bank has
shown that the molecular structures of over 30 germa-
tranes have been documented [1–27]. The germatrane
structure consists of a distorted trigonal bipyramid
,
Ge’N bonds (2.011 A for 1-fluorogermatrane [24],
,
2.081 A for 1-isothiocyanatogermatrane [17], while
containing an in-
,
2.238 A for 1-t-butylgermatrane [5]). The same ten-
dency exists for silatranes (Si’N 1.965–2.24 A) [28–
,
32]. Some changes in the germatranyl groups
(replacement of one CH2 group for CꢁO or CHꢀCH3,
or CHꢀC2H5) does not significantly change the Ge’N
value [33–35].
We have shown [36] that the Ge’N bond in crystals
is considerably shorter than that in isolated germatrane
molecules due to the crystal packing effect. Therefore,
the main aim of this investigation was to study the
molecular structure of tolylgermatranes in crystals as
well as in the free state, to determine the influence of
the position of the methyl group on the values of bond
angles and on the length of intramolecular Ge’N
donor–acceptor bond.
,
at Ge (DGe is 0.095–0.37 A) with nearly equatorial
O atoms. The axial N is pyramidalized so that its
lone pair points towards Ge. The transannular Ge’N
At the same time we are also interested in the study
of the biological properties of this class of compounds.
* Corresponding author. Tel.: +371-7551822; fax: +371-7821031.
E-mail address: ign@osi.lanet.lv (E. Lukevics)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00378-2

E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
223
Table 1
N“Ge bond lengths (A) in germatranes
Table 1 (Continued)
,
,
R
N“Ge (A)
Refs.
2-MeC6H4
H2NCOCH2CH2
Me3C
2.230
2.231
2.238
2.24
This work a
[8]
[5]
[1]
,
R
N“Ge (A)
Refs.
Et
F
NCS
Br
2.011
2.084
2.094
[24]
[17]
[6]
2.24
[2]
2.105
[20]
(Me3Si)2N
N(CH2CH2O)3GeCH2
2.242
2.29
[27]
[4]
Ph3SiO
Me3SiO
2.126
2.128
[16]
[20]
a Preliminary communication [25].
2.144
2.146
2.15
[20]
[10]
[13]
It has been shown that the majority of the organoger-
manium compounds possess lower toxicity than the
corresponding sila analogues, while the other biologi-
cal properties appear to be similar. But these com-
pounds can dramatically differ in the degree of
activity. In this work, we have tested toxicity and
neurotropic activity of germatranes I and II.
HO
2. Results and discussion
2.156
[20]
Tolylgermatranes (II–IV) were obtained as a result
of the following conversions: insertion of germanium
dibromide into the carbonꢀbromine bond of the cor-
responding bromotoluenes, conversion of tolyltribro-
mogermanes into triethoxy derivatives by alcoholysis,
and transalkoxylation with triethanolamine to germa-
tranes II–IV (yields 15, 25 and 14%, respectively).
Phenylgermatrane (I) was synthesized in 67% yield by
condensation of iodobenzene with GeCl4 in the pres-
ence of copper followed by alcoholysis and cyclization
(Scheme 1). Yields, melting points, element analysis
MeOOCCHPh
PhCꢂC(CHCl3)
2.158
2.160
[22]
[21]
2.165
2.166
[7]
[21]
1
and H-NMR data for new compounds obtained are
summarized in Table 2. After recrystallization from
chloroform (II), chloroform–hexane (III, IV) or chlo-
roform–pentane (I), they were obtained as colourless
crystals suitable for an X-ray diffraction study.
ClCH2
4-ClC6H4CONHCH2
ICH2
MeOOC(CH2)3
CH2ꢁCHꢀCH2
MeOOCCHSiMe3
MeOOC(CH2)2
Ph
2.168
2.185
2.19
[14,15]
[11]
[3]
[18]
[23]
2.198
2.208
2.209
2.210
2.212
2.214
2.217
2.22
To further our stereochemical investigation of
atranes the crystals of germatranes I–IV were ana-
lyzed by means of X-ray diffraction. Tables 3–6 give
the atomic coordinates for non-hydrogen atoms with
thermal parameters for molecules I–IV. Figs. 1–4
show a perspective view of molecular structures I–IV
with atomic labels. The crystal structure I is iso-
morphous to b-modification of phenylsilatrane [37].
The crystal structure II is also isomorphous to the
corresponding silatrane structure [38]. The value of
the intramolecular Ge’N donor–acceptor bond
[22]
[19]
This work a
This work
This work a
[22]
3-MeC6H4
4-MeC6H4
MeOOCCMe2
2.223
[9]
,
length for phenylgermatrane (I) is 2.212(5) A. The

224
E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
corresponding distances for tolylgermatranes are
slightly longer: 2.217(4) for p- (II), 2.214(7) for
,
m- (III) and 2.230(11) A for the o-isomer (IV). This
bond in arylgermatranes is longer than that in the
corresponding furyl- and thienylgermatranes [39].
More significant changes have been found for
NꢀGeꢀC angles. For phenylgermatrane (I), p-tolyl-
(II) and m-tolyl- (III) the NꢀGeꢀC angle was close to
linear. Introduction of a methyl group into o-position
of the benzene ring decreases the angle value from
177.5 to 144.2°.
It has been previously shown [36] that the quantum
chemical MNDO SCF molecular orbital method can
be used for silatranes and germatranes. In accordance
with the results obtained in the work by Belyakov et
al. [36] the MNDO approximation gives more accu-
rate data than other quantum chemical patterns.
Therefore, to continue our quantum chemical study of
atrane molecules the MNDO calculations for I–IV
have been performed. Table 7 lists the geometrical
characteristics of molecules I–IV in crystals and in
the free state obtained from MNDO calculations. Ac-
cording to the quantum chemical calculations the
Ge’N bond length is practically constant for iso-
lated molecules I–IV. As shown in Ref. [36], the
shortening of the Ge’N bond in germatrane crystal
leads to the lengthening of Ge–C bonds. This is also
observed for compounds I–IV. Accordingly, the bond
orders of Ge’N for molecules in crystals are greater
than those in the free state (see Table 7). The oppo-
site effect is observed for the Ge–C bonds. The other
bond orders for the isolated molecules almost coincide
with the corresponding values for molecules in crys-
tals. Analogously, the theoretical bond lengths (except
for Ge’N and GeꢀC) are near to the X-ray crystal
analysis data. Thus, the lengthening of the Ge’N
bond in the atrane systems for isolated molecules is
realized without change of other bonds in the rings.
This lengthening is achieved, mainly, due to the
change of the valence and, especially, of the torsion
angles in atranes. Therefore, the zigzag conformation
of the atrane system in crystals differs from that in
the isolated molecules. It can be seen in Fig. 5 where
the projections of molecules I (without H atoms) on
the Ge’N bond are illustrated. As the potential en-
ergy of angle changes is not significant [40], the devia-
tion of the angles from optimum values practically
does not affect the molecule energy.
With the exception of the shortening of the Ge’N
bond, the deviations (DGe) of the Ge atom from the
O2ꢀO8ꢀO9 plane are shorter in germatrane crystals.
The values of DGe in crystals I–IV are 0.238–0.263
,
A, while in the isolated molecules these values are

E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
225
Although the Ge’N bond lengths in isolated
molecules I–IV are identical, these values in crystals of
the compounds are different. This fact may be ex-
plained by the influence of packing effects. Table 8
gives the packing coefficients and densities of crystals
I–IV. The more dense packing promotes the shortening
of the Ge’N bond. The more friable crystal structure
furthers the disorder. It occurs in the crystal structures
of II and IV, where the packing coefficients are less
than in crystals I and III.
Scheme 1.
Previously, we discovered that many organogerma-
tranes exhibit very low toxicity (LD50 for white mice
more than 2000 mg kg−1). The more detailed investiga-
tion allowed us to demonstrate that the acute toxicity
and neurotropic activity of germatranes depend
strongly on the substituent structure at the germanium
atom [41].
Table 3
Atomic coordinates and equivalent isotropic thermal parameters in
germatrane I
Biological investigations have demonstrated that
phenyl- (I) and p-tolylgermatranes (II) are highly toxic
compounds (LD50 35.5 and 70.0 mg kg−1). Phenylger-
matrane (I) is 100 times less toxic than the correspond-
ing silatrane. The introduction of the methyl group into
the p-position lowers the toxicity of germatranes (LD50
70 mg kg−1) but increases this parameter for p-tolylsi-
latrane (0.2 mg kg−1) [42].
Atom
x
y
z
Ueq
Ge(1) 0.32111(2)
−0.35200(7)
−0.2298(8)
−0.2116(13)
−0.3865(11)
−0.4259(7)
−0.2910(14)
−0.2511(13)
−0.2249(7)
−0.6213(6)
−0.7394(11)
−0.6410(10)
−0.2861(9)
−0.4304(10)
0.25(0)
0.0225(2)
0.0389(11)
0.042(2)
0.041(2)
0.0279(10)
0.046(2)
O(2)
C(3)
C(4)
N(5)
C(6)
C(7)
O(8)
O(9)
C(10) 0.2668(5)
C(11) 0.2289(5)
C(12) 0.4097(3)
C(13) 0.4416(3)
C(14) 0.4968(4)
C(15) 0.5223(4)
C(16) 0.4930(4)
C(17) 0.4376(4)
0.2380(3)
0.1570(4)
0.1394(4)
0.2164(3)
0.2274(4)
0.3202(4)
0.3607(3)
0.3307(3)
0.1733(4)
0.2225(6)
0.3012(7)
0.3668(4)
0.4646(6)
0.4787(6)
0.3739(4)
0.2446(9)
0.2916(7)
0.3965(7)
0.1416(5)
0.0660(5)
0.041(2)
0.0365(10)
0.0428(12)
0.042(2)
0.046(2)
3. Experimental
0.0256(11)
0.0319(13)
0.042(2)
0.045(2)
0.038(2)
Standard inert atmosphere techniques were used for
all syntheses and sample manipulations. The solvents
were dried by standard methods and distilled under
−0.3739(13) −0.0211(7)
−0.1786(12) −0.0318(7)
−0.0359(11)
−0.0874(10)
0.0440(7)
0.1294(6)
0.0345(13)
argon prior use. Arylhalogenides
— commercially
available compounds — were distilled prior use under
vacuo.
PMR spectra were conventionally recorded on a
Bruker WH-90/DS spectrometer for 5–7% solutions in
CDCl3 with TMS as internal standard.
For X-ray crystal structure analysis of compounds
I–IV a four-circle computer-controlled single-crystal
Syntex P21 diffractomer with graphite-monochromated
,
0.609–0.628 A. As follows from Table 7 the deviations
(DN) of the N atom from the C4ꢀC6ꢀC11 plane, in
contrast, are longer in crystals.
The lengthening of the transannular bond in isolated
molecules leads to the increase of CꢀGeꢀO valence
angles. Therefore, there is a considerable difference in
theoretical and X-ray values. The low values of
CꢀGeꢀO angles in crystals of compound IV result in
shortened intramolecular contacts between the oxygen
atom and hydrogens of the methyl group (distance
,
Mo–Ka (u=0.71069 A) radiation was used for inten-
sity data collection. Reflection intensities were collected
at room temperature (r.t.) using the q/2q scan tech-
nique. Multisolution direct method package SHELX-86
[43] was used for solution of the structures. SHELXL-93
programs [44] were used for the refinement calculations.
Other crystallographic, measurement and refinement
data for I–IV are given in Table 9. Earlier we reported
[25] the X-ray structures I, II and IV without adducing
the atomic coordinates. In this work the more accurate
data for germatrane IV are given. The data of com-
pound III are presented for the first time. The CCDC
deposition numbers for the structures III and IV are
,
O2···H1(C18) is 2.70 A). That is why the NꢀGeꢀC angle
in crystals of IV differs from the flat angle. In isolated
molecules of IV the distances between O and H are
larger than in crystals (distance O2···H1(C18) is equal
,
2.92 A), therefore, the NꢀGeꢀC angle approaches the
flat angle.

226
E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
Table 4
Atomic coordinates and equivalent isotropic thermal parameters in germatrane II
Atom
Molecule A
Molecule B a
x
y
z
Ueq
x
y
z
Ueq
Ge(1)
O(2)
C(3)
C(4)
N(5)
C(6)
C(7)
O(8)
O(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(4%)
C(6%)
C(11’)
0.29758(4)
0.3804(2)
0.3450(5)
0.2374(5)
0.1845(3)
0.1048(4)
0.1503(5)
0.2238(3)
0.2507(3)
0.1652(6)
0.1556(7)
0.3991(3)
0.4857(4)
0.5559(4)
0.5448(4)
0.4581(4)
0.3872(5)
0.6219(7)
–
0.16870(3)
0.2524(3)
0.3152(5)
0.3404(5)
0.2517(3)
0.2694(5)
0.2759(5)
0.2058(3)
0.0734(3)
0.0878(5)
0.1891(6)
0.0966(3)
0.0710(4)
0.0151(4)
0.04908(3)
0.0070(3)
0.0363(2)
0.0567(10)
0.0703(19)
0.074(2)
0.0465(11)
0.0637(16)
0.0608(16)
0.0572(10)
0.0624(11)
0.077(2)
0.079(2)
0.0356(11)
0.0468(13)
0.0518(15)
0.0472(13)
0.0516(14)
0.0477(15)
0.077(2)
–
0.79088(4)
0.8662(3)
0.8240(5)
0.7143(6)
0.6715(3)
0.6489(7)
0.6703(7)
0.7529(3)
0.7165(3)
0.6312(5)
0.5886(6)
0.8955(4)
0.9344(4)
1.0091(4)
1.0483(4)
1.0113(4)
0.9355(4)
1.1315(7)
0.725(2)
0.17654(3)
0.2716(3)
0.3404(6)
0.3537(6)
0.2572(3)
0.2055(6)
0.1007(6)
0.0858(3)
0.2012(3)
0.2580(6)
0.2569(7)
0.1042(3)
0.0218(4)
−0.0280(4)
0.0021(4)
0.0840(5)
0.1355(4)
−0.0552(8)
0.310(2)
0.38712(3)
0.4432(3)
0.4952(6)
0.4561(7)
0.4401(3)
0.5200(6)
0.5086(7)
0.4617(3)
0.2755(3)
0.2713(5)
0.3584(5)
0.3405(3)
0.3833(5)
0.3505(5)
0.2728(5)
0.2299(4)
0.2612(4)
0.2389(9)
0.529(2)
0.0389(2)
0.0675(12)
0.071(2)
0.073(3)
0.0456(10)
0.065(2)
−0.0678(5)
−0.0653(6)
−0.0470(3)
0.0087(5)
0.1110(4)
0.1355(2)
−0.0287(3)
−0.0959(6)
−0.1277(5)
0.1303(3)
0.0989(4)
0.1524(4)
0.2409(4)
0.2731(4)
0.2199(4)
0.2958(6)
–
0.076(2)
0.0659(11)
0.0633(11)
0.0649(18)
0.065(2)
0.0417(12)
0.0551(14)
0.0644(17)
0.0579(16)
0.0621(17)
0.0552(14)
0.100(3)
−0.0172(4)
0.0081(4)
0.0640(4)
−0.0794(6)
–
–
–
0.026(6)
0.043(9)
0.037(9)
–
–
–
–
–
–
0.612(3)
0.626(3)
0.172(2)
0.317(3)
0.475(3)
0.373(3)
a In molecule B the g-factors for atoms C(4), C(6) and C(11) are 0.85 for atoms C(4%), C(6%) and C(11%) are 0.15.
118916 and 118917, respectively. The ciphers of the
structures I and II in CCDB are RENWUC and
RENXAJ.
The quantum chemical calculations of electronic
structure for the studied systems were performed by the
SCF method using the MNDO approximation
analogously to work [36].
cooled to 0°C and a white solid of 1-phenylgermatrane
(1.31 g, 67%) was filtered off. Recrystallization from a
chloroform–pentane (1:1.8) mixture was carried out.
Analytical data are summarized in Table 2.
Table 5
Atomic coordinates and equivalent isotropic thermal parameters in
germatrane III
3.1. Phenylgermatrane (I)
Atom
x
y
z
Ueq
Iodobenzene (10.5 g, 0.051 mol), germanium tetra-
chloride (12.3 g, 0.057 mol) and 10 g (0.16 g-at) copper
powder were heated in a sealed ampoule for 7 h at
200°C. The content was cooled and filtered directly to a
distilling apparatus under Ar. A yellow solution was
distilled in vacuo and the fraction boiling at 80°C/3.5
mmHg was collected to yield phenyltrichlorogermane
1.7 g (yield 13%). To a phenyltrichlorogermane solution
(1.7 g, 0.0066 mol) in abs. Et2O (10 ml), cooled to 0°C,
was added dropwise an ethanol solution (10 ml) of
triethylamine (1.95 g, 0.02 mol) followed by heating to
r.t. and boiling for 2 h. After cooling, pentane (15 ml)
was added and the triethylamine salt was filtered off.
Triethanolamine (1.0 g, 0.007 mol) in ethanol solution
(15 ml) was added dropwise to the filtrate cooled to
0°C. The reaction mixture was stirred at r.t. for 10 h,
Ge(1)
O(2)
C(3)
C(4)
N(5)
C(6)
C(7)
O(8)
O(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
0.15950(13)
0.17743(6)
0.0862(5)
0.1166(8)
0.2225(11)
0.2804(6)
0.3271(11)
0.3278(9)
0.2437(5)
0.2376(5)
0.3050(8)
0.3479(12)
0.0826(6)
0.0388(6)
0.27833(8)
0.2725(7)
0.2551(12)
0.3013(17)
0.2821(7)
0.1695(11)
0.1138(10)
0.1488(6)
0.4144(6)
0.4640(10)
0.3750(12)
0.2813(8)
0.1745(8)
0.1762(9)
0.2825(8)
0.3821(10)
0.3813(8)
0.0642(10)
0.0338(3)
0.061(2)
0.064(3)
0.109(6)
0.0391(17)
0.083(4)
0.062(3)
0.0545(18)
0.0535(17)
0.065(3)
0.116(7)
0.0359(19)
0.040(2)
0.042(2)
0.044(2)
0.053(3)
0.040(2)
0.064(3)
−0.0011(10)
−0.1748(15)
−0.157(2)
−0.0392(10)
−0.154(2)
−0.0455(17)
0.0760(10)
0.3348(10)
0.2736(16)
0.0859(19)
0.3301(13)
0.2851(14)
0.3902(13) −0.0401(6)
0.5480(13) −0.0767(7)
0.6045(13) −0.0327(8)
0.4885(14)
0.3320(18) −0.0871(9)
0.0480(6)

E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
227
Table 6
Atomic coordinates and equivalent isotropic thermal parameters in
germatrane IV
Atom
x
y
z
Ueq
Ge(1)
O(2)
C(3)
0.1211(3)
0.0016(10) −0.0564(7)
−0.1263(15) −0.0487(9)
0.0493(3)
0.0(0)
0.0166(9)
0.0570(15) 0.098(19)
0.0706(27) 0.123(33)
0.1197(27) 0.083(32)
0.0468(10)
0.059(6)
a
C(4)
−0.1821(28)
−0.1621(29)
−0.0643(10)
−0.0254(29)
−0.0080(28)
0.1104(17)
0.1870(10)
0.1197(10)
−0.0072(16)
−0.0612(29)
−0.1014(29)
0.0599(21)
0.0547(21)
0.1324(8)
0.1459(21)
0.1915(21)
0.1532(9)
0.0869(5)
0.1479(5)
0.2023(8)
0.2349(22)
C(4%) a
N(5)
0.0690(9)
0.056(7)
C(6) a
C(6%) a
C(7)
0.2026(26) 0.025(28)
0.1739(26) 0.092(32)
0.2202(10) 0.086(12)
0.1463(8)
−0.1172(8)
O(8)
O(9)
0.079(8)
0.091(9)
C(10)
C(11) a
C(11%) a
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
−0.1207(12) 0.149(25)
0.0041(22) 0.059(25)
Fig. 2. Perspective view and atom numbering scheme of molecule II.
0.2041(22) −0.0355(22) 0.067(32)
0.2825(19) −0.0251(9)
0.3383(21) −0.1143(9)
0.0490(9)
−0.0044(9)
0.1197(9)
0.061(9)
0.077(8)
0.186(51)
0.172(28)
−0.1621(23)
0.0547(9)
0.2758(23) −0.1741(9)
0.4610(23) −0.1626(9)
−0.1090(9)
0.0304(11) 0.105(15)
0.1501(9) 0.084(12)
0.1959(14) 0.137(22)
0.3521(22)
0.0148(9)
0.4631(24) −0.0399(9)
a For atoms C(4), C(4%), C(6), C(6%), C(11) and C(11%) the occupa-
tion g-factors equal 0.5.
Fig. 3. Perspective view and atom numbering scheme of molecule III.
Fig. 1. Perspective view and atom numbering scheme of molecule I.
3.2. m-Tolylgermatrane (III)
Fig. 4. Perspective view and atom numbering scheme of molecule IV.
m-Bromotoluene (6.35 g, 0.037 mol) and a dioxane
complex of germanium (II) dibromide (5.65 g, 0.018
mol) were heated for 30 h at 200°C in a sealed am-
poule. The resultant yellow solution was distilled in
vacuo, and a fraction boiling at 95–105°C/3 mmHg
was collected to yield m-tolyltribromogermane (1.56 g,
21.5%). An ethanolic solution (10 ml) of triethylamine
(1.17 g, 0.012 mol) was added dropwise to a m-tolyltri-

228
E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
Table 7
The principal geometrical parameters of molecules I–IV and MNDO calculated bond orders (in square brackets); X-ray analysis results in
comparison with the values for isolated molecules
I
II
III
IV
Crystal state
,
N“Ge (A)
2.212(5)
1.947(6)
1.797(4)
1.404(8)
1.514(9)
1.475(8)
–
177.5(2)
97.9(2)
0.238(1)
0.371(3)
[0.221]
[0.759]
[0.628]
[1.024]
[0.921]
[0.931]
2.217(4)
1.946(5)
1.792(3)
1.405(7)
1.510(10)
1.467(9)
1.509(8)
179.0(2)
97.8(2)
[0.219]
[0.760]
[0.629]
[1.024]
[0.921]
[0.932]
[0.983]
2.214(7)
1.947(11)
1.792(7)
1.416(16)
1.51(2)
[0.220]
[0.760]
[0.629]
[1.023]
[0.921]
[0.932]
[0.983]
2.230(11)
1.94(2)
1.798(14)
1.38(3)
1.48(3)
1.46(3)
1.51(3)
144.2(8)
95.2(8)
0.263(2)
0.407(17)
[0.217]
[0.762]
[0.628]
[1.024]
[0.921]
[0.931]
[0.982]
,
GeꢀC (A)
GeꢀO(mean) (A)
,
,
OꢀC(mean) (A)
CꢀC(mean) (A)
CꢀN(mean) (A)
CꢀMe (A)
N“GeꢀC (°)
CꢀGeꢀO(mean) (°)
,
,
1.43(2)
,
1.503(18)
176.3(3)
98.1(4)
0.253(2)
0.394(9)
,
DGe (A)
DN (A)
0.245(2)
0.363(4)
,
Free state
,
N“Ge (A)
2.759
1.915
1.814
1.380
1.542
1.478
–
179.8
110.3
0.609
0.292
[0.062]
[0.787]
[0.650]
[1.001]
[0.921]
[0.935]
2.763
1.918
1.814
1.381
1.542
1.479
1.507
179.6
109.3
0.610
0.292
[0.061]
[0.787]
[0.651]
[0.998]
[0.922]
[0.935]
[0.983]
2.758
1.919
1.813
1.380
1.543
1.478
1.505
179.5
109.5
0.614
0.295
[0.062]
[0.787]
[0.651]
[0.999]
[0.921]
[0.936]
[0.983]
2.791
1.932
1.815
1.382
1.540
1.477
1.510
178.4
110.2
0.628
0.283
[0.056]
[0.787]
[0.649]
[0.998]
[0.922]
[0.936]
[0.981]
,
GeꢀC (A)
GeꢀO(mean) (A)
,
,
OꢀC(mean) (A)
CꢀC(mean) (A)
CꢀN(mean) (A)
CꢀMe (A)
N“GeꢀC (°)
CꢀGeꢀO(mean) (°)
,
,
,
,
DGe (A)
DN (A)
,
bromogermane solution (1.56 g, 0.004 mol) in abs. Et2O
(10 ml), cooled to 0°C, followed by heating to r.t. and
boiling for 2 h. After cooling pentane (15 ml) was
added and triethylamine salt was filtered off. Tri-
ethanolamine 0.57 g (0.004 mol) in an ethanol solution
(15 ml) was added dropwise to the filtrate cooled to
0°C. The reaction mixture was stirred at r.t. for 8 h,
cooled to 0°C and m-tolylgermatrane (0.3 g, 25.0%)
was filtered off. Recrystallization from a chloroform–
hexane (1:1) mixture was carried out. Analytical data
are summarized in Table 2.
Fig. 5. Projection of molecular structure I along the Ge’N bond in
crystals (a) and in the free state (b).
Compounds II and IV were prepared analogously.
After recrystallization compound II (from chloroform)
and compound IV (from chloroform–hexane (1:2)) had
properties shown in Table 2.
Table 8
Crystal density and packing coefficient for I–IV
Density (g cm−3
)
Packing coefficient
Acknowledgements
Compound
I
II
III
IV
1.582(1)
1.526(1)
1.559(1)
1.505(1)
0.733(1)
0.665(1)
0.679(1)
0.656(1)
The authors are grateful to Dr J. Popelis for record-
ing 1H-NMR spectra, Dr S. Germane for biological
investigations and Mrs L. Khokhlova for assistance in
synthesis.

E. Luke6ics et al. / Journal of Organometallic Chemistry 588 (1999) 222–230
229
Table 9
Crystal data, measurement conditions and refinement results for compounds I–IV
I
II
III
IV
Molecular weight Mr
Crystal size (mm3)
Crystal system
295.86
309.88
309.88
309.88
0.35×0.30×0.30
Orthorhombic
Pna21
0.40×0.25×0.20
Monoclinic
P21/c
1.00×0.50×0.20
Monoclinic
P21/c
0.60×0.30×0.25
Orthorhombic
Pna21
Space group
Cell parameters
,
a (A)
15.910(2)
6.661(1)
11.719(2)
90.0
1242.0(3)
4
13.608(3)
14.012(3)
14.330(2)
99.13(1)
2697.8(9)
8
8.527(4)
13.464(6)
14.253(6)
126.20(3)
1320.4(10)
4
9.759(3)
12.725(3)
11.015(3)
90.0
1367.9(6)
4
,
b (A)
,
c (A)
i (°)
3
,
Unit cell volume V (A )
Molecular multiplicity Z
F(000)
608
2.462
1280
2.271
640
2.320
640
2.240
Absorption coefficient v (mm−1
)
Data collection
2qmax (°)
50
45
50
50
h
k
l
0“18
0“7
0“13
1120
1120
1083
0“14
0“15
−15“15
3783
3547
2872
−10“8
0“16
0“16
2465
2302
1775
0“11
0“15
0“13
1261
1261
887
Number of measured reflections
Number of independent reflections
Number of observed reflections (I\2|I)
Refinement data
R factor
R(F) for all data
wR(F2) for all data
Goodness-of-fit
(D/|)max
0.0323
0.0333
0.0841
1.082
0.045
222
0.0458
0.0572
0.1253
1.055
0.067
490
0.0699
0.0804
0.2016
0.914
0.043
163
0.0745
0.1012
0.2202
1.024
0.064
160
Number of parameters
Flack’s x parameter
−0.01(3)
–
–
0.03(7)
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