New Stable Germylenes, Stannylenes, and Related Compounds. 3. Stable Monomers XGeOCH2CH2NMe2 (X = Cl, OCOMe) with only One Intramolecular Coordination Metal-Nitrogen Bond: Synthesis and Structure

Article abstract of DOI:10.1021/om034068+

New stable monomeric germanium(II) derivatives XGeOCH₂CH ₂NMe₂ (1, X = Cl; 2, X = OCOMe) with ligands that are not sterically bulky at the Ge atom and only one intramolecular coordination Ge←N_sp3 bond have been

Full text of DOI:10.1021/om034068+

Organometallics 2003, 22, 5441-5446
5441
New Sta ble Ger m ylen es, Sta n n ylen es, a n d Rela ted
Com p ou n d s. 3. Sta ble Mon om er s XGeOCH CH NMe (X )
2
2
2
Cl, OCOMe) w ith On ly On e In tr a m olecu la r Coor d in a tion
Meta l-Nitr ogen Bon d : Syn th esis a n d Str u ctu r e
,
†
†
‡
Nikolay N. Zemlyansky,* Irina V. Borisova, Victor N. Khrustalev,
‡
,§
§
Mikhail Yu. Antipin, Yuri A. Ustynyuk,* Mikhail S. Nechaev, and
Valery V. Lunin§
A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences (TIPS RAS),
2
9 Leninsky prosp., 119991-GSP-1, Moscow, Russia, A. N. Nesmeyanov Institute of
Organoelement Compounds, Russian Academy of Sciences, 28 ul. Vavilova, 119991 Moscow,
Russia, and Department of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119899 Moscow, Russia
Received J uly 25, 2003
2 2 2
New stable monomeric germanium(II) derivatives XGeOCH CH NMe (1, X ) Cl; 2, X )
OCOMe) with ligands that are not sterically bulky at the Ge atom and only one
3
intramolecular coordination GerNsp bond have been synthesized. The molecular and crystal
structures of these compounds were studied by X-ray diffraction analysis. The electronic
structures of 1 and 2 were studied by DFT. Compound 2 is the first structurally characterized
acyloxy derivative of germanium(II).
In tr od u ction
The compound AcOGeOCH2CH2NMe2 (2) has been
prepared in 67% yield by the reaction of (N,N-dimethyl-
aminoethoxy)triethyltin with germanium(II) acetate (5)
at 1:1 reagent ratio in THF at room temperature
The chemistry of stable organic derivatives of divalent
germanium and tin has developed very rapidly in the
last decades.1 Steric protection of the metal atom by
bulky substituents R and intramolecular coordination
MrY (Y ) N, O) with donor groups of suitable geometry
in the side chain are two main factors responsible for
their kinetic and thermodynamic stabilization. Mono-
meric germanium(II) compounds with small ligands are
so far practically unknown. In continuation of our study
,2
(Scheme 2).
(2) Recent selected publications: (a) J utzi, P.; Keitemeyer, S.;
Neumann, B.; Stammler, A.; Stammler, H.-G. Organometallics 2001,
0, 42. (b) J utzi, P.; Keitemeyer, S.; Neumann, B.; Stammler, H.-G.
2
Organometallics 1999, 18, 4778. (c) Schmidt, H.; Keitemeyer, S.;
Neumann, B.; Stammler, H.-F.; Schnoeller, W. W.; J utzi, P. Organo-
metallics 1998, 17, 2149. (d) Barrau, J .; Rima, G.; El Amraoui, T.
Organometallics 1998, 17, 607. (e) Barrau, J .; Rima, G.; El Amraoui,
T. J . Organomet. Chem. 1998, 561, 167. (f) Akkari, A.; Byrne, J . J .;
Saur, I.; Rima, G.; Gornitzka, H.; Barrau, J . J . Organomet. Chem. 2001,
3
on germanium(II) compounds we report here the
synthesis and the results of experimental (X-ray, NMR)
and DFT theoretical studies of two stable monomeric
compounds, XGeOCH2CH2NMe2 (1, X ) Cl; 2, X ) OAc),
stabilized by only one intramolecular coordination
GerNsp3 bond without any steric protection. Rare
examples of such compounds, namely, dialkoxy deriva-
6
22, 190. (g) Eaborn, C.; Hill, M. S.; Hitchcock, P. B.; Patel, D.; Smith,
J . D.; Zhang, S. Organometallics 2000, 19, 49. (h) Borisova, I. V.;
Eaborn, C.; Hill, M. S.; Khrustalev, V. N.; Kuznetzova, M. G.; Smith,
J . D.; Ustynyuk, Yu. A.; Lunin, V. V.; Zemlyansky, N. N. Organome-
tallics 2002, 21, 4005. (i) Chorley, R. W.; Hitchcock, P. B.; J olly, B. S.;
Lappert, M. F.; Lawless, G. A. J . Chem. Soc., Chem. Commun. 1991,
1302. (j) Leung, W.-P.; Kwok, W.-H.; Zhou, Z.-Y.; Mak, T. C. W.
Organometallics 2003, 22, 1751. (k) J astrzebski, J . T. B. H.; van der
Schaaf, P. A.; Boersma, J .; van Koten, G.; Zoutberg, M. C.; Heljdenrijk,
D. Organometallics 1989, 8, 1373, and references therein. (l) Ayers,
A. E.; Klap o¨ tke, T. M.; Dias, H. V. R. Inorg. Chem. 2001, 40, 1000. (m)
Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.; Power, P. P.
Organometallics 2001, 20, 1190. (n) Ding, Y.; Hao, H.; Roesky, H. W.;
Noltemeyer, M.; Schmidt, H.-G. Organometallics 2001, 20, 4806. (o)
Ding, Y.; Ma, Q.; Roesky, H. W.; Herbst-Irmer, R.; Us o´ n, I.; Noltemeyer,
M.; Schmidt, H.-G. Organometallics 2002, 21, 5216. (p) Kitamura, C.;
Maeda, N.; Kamada, N.; Ouchi, M.; Yoneda, A. J . Chem. Soc., Perkin
Trans. 2000, 1, 781. (q) Veith, M.; Rammo, A. Z. Anorg. Allg. Chem.
4
a
4b
tive MeN(CH2CH2O)2Ge,
oxyisobutyrate,
oxy-
4
c,d
and oxythiosalicylate4c,d germanium(II),
salicylate,
have been reported previously without structural char-
acterization.
Resu lts a n d Discu ssion
The chloro derivative ClGeOCH2CH2NMe2 (1) is
formed easily in 74% yield by the exchange of one
chelating OCH2CH2NMe2 ligand of Ge(OCH2CH2NMe2)2
3) in the 1:1 redistribution reaction with GeCl2‚D (D
dioxane) (4) in THF at 20 °C (Scheme 1).
2
001, 627, 662. (r) Eichler, B. E.; Power, P. P. J . Am. Chem. Soc. 2000,
122, 8785. (s) Francis, M. D.; Hitchcock, P. B. Organometallics 2003,
2, 2891. (t) Richards, A. F.; Phillips, A. D.; Olmstead, M. M.; Power
3
2
(
)
P. P. J . Am. Chem. Soc. 2003, 125, 3204. (u) Setaka, W.; Sakamoto,
K.; Kira, M.; Power, P. P. Organometallics 2001, 20, 4460. (v) Karsch,
H. H.; Schl u¨ ter, P. A.; Reisky, M. Eur. J . Inorg. Chem. 1998, 433. (w)
Foley. S. R.; Bensimon, C.; Richeson, D. S. J . Am. Chem. Soc. 1997,
119, 10359. (x) Dias, H. V. R.; Wang, Z. J . Am. Chem. Soc. 1997, 119,
4650.
*
Address correspondence to these authors. N.N.Z.: E-mail
zemlyan@mail.cnt.ru. Y.A.U.: E-mail yust@nmr.chem.msu.su.
†
A. V. Topchiev Institute of Petrochemical Synthesis.
A. N. Nesmeyanov Institute of Organoelement Compounds.
Moscow State University.
1) Recent reviews: (a) Tokitoh, N.; Okazaki, R. Coord. Chem. Rev.
‡
(3) (a) Khrustalev, V. N.; Borisova, I. V.; Zemlyanskii, N. N.;
Ustynyuk, Yu. A.; Antipin, M. Yu. Crystallogr. Rep. 2002, 47, 616. (b)
Zemlyansky, N. N.; Borisova, I. V.; Khrustalev, V. N.; Ustynyuk, Yu.
A.; Nechaev, M. S.; Lunin, V. V.; Barrau, J .; Rima, Organometallics
2003, 22, 1675.
§
(
2
000, 210, 251. (b) Barrau, J .; Rima, G. Coord. Chem. Rev. 1998, 178-
1
80, 593.
1
0.1021/om034068+ CCC: $25.00 © 2003 American Chemical Society
Publication on Web 11/21/2003

5
442 Organometallics, Vol. 22, No. 26, 2003
Zemlyansky et al.
Sch em e 1
Sch em e 2
Sch em e 3
F igu r e 1. Molecu la r str u ctu r e of 1 (50% p r oba bility
ellip soid s).
Both 1 and 2 are white crystalline substances that
are very sensitive to traces of oxygen and moisture. They
are moderately soluble in THF and dichloromethane
1
and slightly soluble in ether and hexane. The H NMR
spectra of 1 and 2 recorded in dichloromethane-d2 at
+40 °C contain sharp A2X2 patterns of CH2CH2 units
and sharp singlets due to the NMe2 groups. This
indicates that a fairly fast dynamic process occurs in
3
solution, during which the GerNsp coordination bonds
1
break and re-form. In the H NMR spectra recorded at
0
°C the triplets due to the CH2N groups and NMe2
group singlets, as well as the singlets due to the OCH2
carbons in the 13C NMR spectra of both substances, are
noticeably broadened due to retardation of this process.
A similar process had been reported for the nitrogen-
and oxygen-coordinated germanium(II) compounds
F igu r e 2. Molecu la r str u ctu r e of 2 (50% p r oba bility
ellip soid s).
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(
d eg) for 1 a n d 2
(
)
Mamx)2Ge [temperature range +80 to -80 °C; Mamx
2,4-Bu-t-6-(Me2NCH2)C6H2],2 (t-Bomx)2Ge [temper-
c
compound
1 (R ) Cl)
2 (R ) OCOMe)
ature range +80 to -40 °C; t-Bomx ) 2,4-Bu-t-6-(t-
BuOCH2)C6H2], and (i-Pomx)2Ge [temperature range
Ge-O
1.820(4)
2.330(2)
2.093(5)
98.0(2)
92.9(2)
84.7(2)
1.832(1)
1.938(1)
2.108(1)
97.09(5)
86.90(5)
84.79(5)
Ge-R
GerN
2
a
∼
20 to -40 °C; i-Pomx ) 2,4-Bu-t-6-(i-PrOCH2)C6H2]
and nitrogen-coordinated tin(II) compounds (ArO)2Sn
Ar ) 2,4,6-(Me2NCH2)3C6H2)2d,e and RSnX [R )
O-Ge-R
NfGe-R
NfGe-O
(
2
i
C(SiMe3)2C5H4N-2, X ) Cl or N(SiMe3)2; R ) CH-
SiMe3)C9H6N-8, X ) CL or Br; R ) 2,6-(Me2NCH2)2-
C6H3, X ) Cl]. We started the study of the NMR
spectra of 1 and 2 in a wide range of temperatures and
concentrations to obtain more detailed information
about this dynamic process.
insoluble in ether and hexane. We have not succeeded
in preparing a crystal of 5 suitable for X-ray analysis.
Our study of the synthesis and reactivity of the series
of other germanium(II) acylates will be reported else-
where.
Crystals suitable for an X-ray structure analysis were
obtained from THF (for 1) and Et2O/THF (for 2) solu-
tion. The molecular structures of 1 and 2 are shown in
Figures1 and 2. Selected bond lengths and angles are
presented in Table 1, and crystallographic data are
given in Table 2.
2
j
(
2
k
Previously unknown germanium(II) acetate, Ge(OAc)2
(5), has been prepared by the reactions of triethyltin
acetate, Et3SnOAc, with GeCl2‚D (4) or with Ge(SBu)2,
which had been synthesized earlier 5 (Scheme 3). The
reverse transformation of 5 into Ge(SBu)2 can be ef-
fected easily by its reaction with Me3SiSBu.
Acetate 5 is a white crystalline substance that is very
sensitive to traces of oxygen and moisture. It is well
soluble in pyridine, THF, and chloroform and practically
In the structures of 1 and 2 the germanium atom is
three-coordinate, forming one σ-bond to each substituent
and an additional NfGe coordination bond. The Ge-N
bond length is 2.093(5) Å for 1 and 2.108(1) Å for 2.
These values are in the same range as those observed
in previously studied amino-functionalized Ge(II) com-
pounds of this type (2.092(3)-2.165(5) Å2 ). The
alkoxide Ge-O bond lengths (1.820(4) Å in 1 and 1.832-
(4) (a) Silverman, L. D.; Zeldin, M. Inorg. Chem. 1980, 19, 272. (b)
Lavayssi e` re, H.; Dousse, G.; Satg e´ , J . Phosphorus, Sulfur, Silicon Relat.
Elem. 1990, 53, 411. (c) Lavayssi e` re, H.; Dousse, G.; Mazieres, S.;
Satg e´ , J . Phosphorus, Sulfur, Silicon Relat. Elem. 1991, 61, 341. (d)
Mazieres, S.; Lavayssi e` re, H.; Dousse, G.; Satg e´ , J . Inorg. Chim. Acta
b,c,6
(
1) Å in 2) are shortened in comparison with that for
1
996, 252, 25.
5) J utzi, P.; Stener, W. Chem. Ber. 1976, 109, 1575.
3
(
Ge(OCH2CH2NMe2)2 (1.861(1)-1.870(1) Å ). The Ge-

New Stable Germylenes
Organometallics, Vol. 22, No. 26, 2003 5443
Ta ble 2. Cr ysta llogr a p h ic Da ta for 1 a n d 2
Ta ble 3. Ca lcu la ted Geom etr y P a r a m eter s of
Molecu les 1a -c (in ter a tom ic d ista n ces in Å,
va len ce a n gles in d eg, d evia tion s fr om X-r a y d a ta
in p a r en th eses)
1
2
empirical formula
fw
C
4
H
10NOClGe
6 3
C H13NO Ge
219.76
200(2)
196.17
110(2)
temperature (K)
cryst size (mm)
cryst syst
space group
a (Å)
1a
1b
1c
0.40 × 0.30 × 0.05 0.30 × 0.15 × 0.10
monoclinic monoclinic
P2 /c P2 /c
6.500(3)
11.203(4)
10.080(5)
90
94.453(9)
90
731.8(5)
4
Ge-O
1.850
1.843
(+0.023)
2.351
(+0.021)
2.093a
(0.000)
100.9
(+2.9)
92.2
1.795
(
+0.034)
2.340
+0.010)
2.252
+0.159)
101.6
1
1
Ge-Cl
2.232
5.067
97.0
12.8127(15)
6.6734(8)
11.5545(15)
90
110.988(3)
90
922.4(2)
4
1.582
(
b (Å)
c (Å)
Ge-N
(
R (deg)
O-Ge-Cl
N-Ge-Cl
N-Ge-O
â (deg)
(
+3.6)
γ (deg)
3
91.3
V (Å )
Z
(+1.6)
81.4
(-3.3)
(-0.7)
83.4
(-1.4)
(g cm-3)
d
c
1.781
F(000)
392
4.462
448
3.285
µ (mm-1)
a
Parameter fixed at the X-ray value in optimization.
θ range (deg)
index range
2.72 to 26.06
-8 e h e 7
3.41 to 28.06
-16 e h e 16
-8 e k e 8
-15 e l e 15
9088
-
13 e k e 9
12 e l e 11
In the crystal the molecules 1 and 2 show no inter-
molecular interactions.
-
no. of reflns collected
no. of unique reflns
4535
1403
2193
no. of reflns with I > 2σ(I) 890
1793
DF T Stu d y of 1 a n d 2
R1; wR2 (I > 2σ(I))
R1; wR2 (all data)
no. of data/restraints/
params
0.0487; 0.1052
0.0215; 0.0496
0.0283; 0.0512
2193/0/103
0.0852; 0.1170
1403/0/113
The molecular and electronic structures of 1 and 2
have been studied using the DFT approach. The geom-
etry optimizations have been carried out using general-
GOF on F2
0.921
0.953
0.001
0.359/-0.250
max shift/error
largest diff peak/hole
0.001
0.906/-0.916
9
ized gradient functional PBE. This functional has
-3
previously been extensively tested on a variety of types
(e Å
)
1
0
abs corr Tmax; Tmin
0.800; 0.281
0.720; 0.398
of molecules. Triple-ú valence basis sets including
polarization functions TZ2P {3,1,1/3,1,1/1,1} for Ge, Cl,
C, N, and O atoms and {3,1,1/1) for H atoms have been
used. Innermost electrons were treated using relativ-
istic effective core potentials ECP-SBKJ C. All station-
ary points were characterized by calculation of Hessian
matrices. In all cases no imaginary frequencies were
found, which corresponds to local minima. Atomic
partial charges were calculated using Hirshfeld’s
Cl bond length in the structure 1 (2.330(2) Å) is equal
2
b
to that in [Mamx]GeCl (2.3283(4) Å ) or in [t-Bomx]-
GeCl (2.333(1) Å 2 ). The acetate Ge-O bond length in
a
11
i (+)
12
2
(1.938(1) Å) is equal to that in the salt [PPh3Pr ] [Ge-
(-)
7
(
OCOMe)3] (1.921(1)-1.948(1) Å ). However, it con-
siderably exceeds the values of the lengths of other
known Ge(II)-O bonds (1.765(6)-1.879(7) Å2
b,6,8a-i
).
The geometry at the germanium atom in the struc-
tures of 1 and 2 is worth mentioning. The angle R (O1-
Ge-N) is smaller than 90° in both compounds (84.7(2)°
in 1 and 84.79(5)° in 2). The angle â (O1-Ge-X, X )
Cl, O) is close to 90° (92.9(2)° in 1 and 86.90(5)° in 2),
and the angle γ (N-Ge-X, X ) Cl, O) is larger than
1
3
method. All calculations have been performed using
1
4
the “PRIRODA” program. This approach and program
have been successfully used by us earlier in the study
of the structures and reactivities of organometallic
betaines, compounds with multiple bonds R2MdX and
heavier analogues of carbenes R2M: (M ) Si, Ge, Sn; X
9
0° (98.0(2)° in 1 and 97.09(5)° in 2). The same distribu-
1
5
tion of the R, â, and γ bond angles (R < â ≈ 90° < γ) is
) CR2, O, S, NR, Se; R ) Alk, Ar).
characteristic of all previously investigated analogous
Although all calculations were performed for isolated
molecules in the gas phase, calculated geometries 1a
and 2a reproduced reasonably well the general features
of 1 and 2 geometries in the crystalline state (Tables 3,
4; Figure 3). Rather large deviations from X-ray data
for 1a and 2a were found, as expected for the relatively
Ge(II) compounds.2
b,c,6
The nitrogen atom is nearly
perpendicular to the O-Ge-X (X ) Cl, O) plane,
allowing ideal interaction of its lone electron pair with
the vacant Ge(p) orbital.
The five-membered heterocycles of 1 and 2 have
envelope conformations with C(2) atom deviations from
the mean-square planes through the rest of the atoms
of 0.561 and 0.564 Å, respectively.
(
9) Perdew, J . P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996,
7
7, 3865.
(
10) (a) Ernzerhof, M.; Scuseria, G. E. J . Chem. Phys. 1999, 110,
5
029. (b) Adamo, C.; Barone, V. J . Chem. Phys. 1999, 110, 6158.
(11) Laikov, D. N. Ph.D. Dissertation, Moscow State University,
(6) Suh, S.; Hoffman, D. M. Inorg. Chem. 1996, 35, 6164.
(
7) Khrustalev, V. N.; Antipin, M. Yu.; Zemlyansky, N. N.; Borisova,
Moscow, 2000.
I. V.; Ustynyuk, Yu. A.; Lunin, V. V.; Izod, K. Unpublished results.
8) (a) C¸ etinkaya, B.; G u¨ mr u¨ k c¸ u¨ , I.; Lappert, M. F.; Atwood, J . L.;
Rogers, R. D.; Zaworotko, M. J . J . Am. Chem. Soc. 1980, 102, 2088.
b) Fjeldberg, T.; Hitchcock, P. B.; Lappert, M. F.; Smith, S. J .; Thorne,
(12) (a) Stevens, W. J .; Basch, H.; Krauss, M. J . Chem. Phys. 1984,
81, 6026. (b) Stevens, W. J .; Krauss, M.; Basch, H.; J asien, P. G. Can.
J . Chem. 1992, 70, 2. (c) Cundari, T. R.; Stevens, W. J . J . Chem. Phys.
1993, 98, 5555.
(
(
A. J . J . Chem. Soc., Chem. Commun. 1985, 939. (c) Hitchcock, P. B.;
Lappert, M. F.; Thomas, S. A.; Thorne, A. J .; Carty, A. J .; Taylor, N.
J . J . Organomet. Chem. 1986, 315, 27. (d) Veith, M.; Kafer, D.; Koch,
J .; May, P.; Stahl, L.; Huch, V. Chem. Ber. 1992, 125, 1033. (e) Veith,
M.; Mathur, C.; Huch, V. Organometallics 1996, 15, 2858. (f) Veith,
M.; Mathur, C.; Huch, V. J . Chem. Soc., Dalton Trans. 1997, 995. (g)
Veith, M.; Mathur, C.; Mathur, S.; Huch, V. Organometallics 1997,
(13) Hirshfeld, F. L. Theor. Chim. Acta (Berlin) 1977, 44, 129.
(14) Laikov, D. N. Chem. Phys. Lett. 1997, 281, 151.
(15) (a) Nechaev, M. S.; Borisova, I. V.; Zemlyansky, N. N.; Laikov,
D. N.; Ustynyuk, Yu. A. Russ. Chem. Bull. 2000, 49, 1823. (b) Borisova,
I. V.; Zemlyansky, N. N.; Khrustalev, V. N.; Kuznetzova, M. G.;
Ustynyuk, Yu. A.; Nechaev, M. S. Russ. Chem. Bull. 2001, 50, 1679.
(c) Ustynyuk, Yu. A.; Nechaev, M. S.; Laikov, D. N.; Borisova, I. V.;
Zemlyansky, N. N.; Chernyshev, E. A. Russ. Chem. Bull. 2001, 50,
771. (d) Borisova, I. V.; Nechaev, M. S.; Khrustalev, V. N.; Zemlyansky,
N. N.; Ustynyuk, Yu. A. Russ. Chem. Bull. 2002, 51, 721.
1
6, 1292. (h) Hascall, T.; Rheingold, A. L.; Guzei, I.; Parkin, G. Chem.
Commun. 1998, 101. (i) McBurnett, B. G.; Cowley, A. H. Chem.
Commun. 1999, 17.

5
444 Organometallics, Vol. 22, No. 26, 2003
Zemlyansky et al.
F igu r e 3. Calculated molecular structures of 1a , 1c, 2a , 2c, and 2d (numbers are calculated Hirshfeld’s partial atomic
charges).
Ta ble 4. Ca lcu la ted Geom etr y P a r a m eter s of
Molecu les 2a -d (in ter a tom ic d ista n ces in Å,
va len ce a n gles in d eg, d evia tion s fr om X-r a y d a ta
in p a r en th eses)
Ta ble 5. Ca lcu la ted En er gies E, E0 ) E + ZP E (a u ),
a n d Rela ted En er gies ∆E0 (k ca l/m ol) of Molecu les
1a -c a n d 2a -d
molecule
E
E0
∆E0
2
a
2b
2c
2d
1
a
-73.47999
-73.47759
-73.45257
-103.73236
-103.72861
-103.71437
-103.72372
-73.33793
-73.33517
-73.31251
-103.54260
-103.53804
-103.52581
-103.53333
0.0
Ge-O1
1.846
+0.014)
2.077
+0.139)
2.389
+0.281)
2.288
-0.465)
95.9
-1.2)
83.2
-3.7)
81.2
-3.6)
1.850
(+0.018)
1.995
(+0.057)
2.108
(0.000)
2.753
(0.000)
98.0
(+0.9)
84.3
(-2.6)
83.5
(-1.3)
1.803
1.843
1b
1c
2a
2b
2c
2d
+1.7
+16.0
0.0
+2.9
+10.5
+5.8
(
Ge-O2
2.090
5.097
2.096
93.6
1.925
2.211
4.072
99.23
84.2
(
a
Ge-N
(
a
Ge-O3
(
1
a , i.e., transition 1a f 1c, is related to the consumption
O1-Ge-O2
N-Ge-O2
N-Ge-O1
of 16.0 kcal/mol (Table 5). In 1c the bond lengths Ge-O
and Ge-Cl and valence angle O-Ge-Cl are reduced
with respect to 1a (Table 3).
Rupture of the Ge-N coordination bond in 2a results
in the formation of isomer 2c (Figure 3), which lies 10.5
kcal/mol higher in energy than 2a (Table 5). The energy
consumption for breaking the Ge-N bond in this case
is partially compensated by strengthening of the coor-
dination with the acetate ligand, which is manifested
(
(
82.6
(
a
Parameter fixed at the X-ray value in optimization.
weak Ge-N coordination bonds (+0.159 Å in 1 and
0.281 Å in 2) and Ge-O3 distance (-0.465 Å in 2). The
acetate group in isolated 2a is bonded to the germanium
atom as an unsymmetrical η -ligand, whereas in crystal
it clearly has η -coordination. To elucidate the reason
+
2
in the significant shortening of the Ge-O distance in
comparison with 2a . The acetate η -coordination in 2c
3
2
1
2
becomes almost symmetrical; the Ge-O2 and Ge-O3
bonds differ only by 0.006 Å (Table 4). Rupture of the
Ge-O3 bond in 2a , i.e., transition 2a f 2d , is associated
with consumption of only 5.8 kcal/mol and accompanied
by considerable shortening of the Ge-N bond in 2d .
Population analysis shows that the HOMO in 1a , 2a ,
and 2d are localized on the metal atoms and occupied
by a lone electron pair (LEP) as shown for 1a (Figure
4). In isomers c the HOMOs are localized on the
nitrogen atoms of the NMe2 groups, which are not
included in the coordination. The LUMOs in 1a , 1c, 2c,
and 2d are mainly localized on the germanium atoms
and represented by a large contribution of the 4pz orbital
of Ge and minor contributions of N and O atoms. The
LUMO in 2a is localized on the acetate ligand.
for these deviations, we optimized the geometries of the
structures 1b and 2b, in which the Ge-N and Ge-O3
distances were fixed at the X-ray values. It was found
that related energies of 1b and 2b differ from the
corresponding values for 1a and 2a only by +1.7 and
+
2.9 kcal/mol, respectively (Table 5). This means that
the potential energy surfaces (PES) of 1 and 2 in the
region of minima are so flat that differences in calcu-
lated and X-ray structures of 1 and 2 are most probably
due to crystal-packing effects.
The local minima that exist on the potential energy
surfaces (PES) of 1 and 2 corresponded to isomeric
structures 1c, 2c, and 2d , in which Ge-N (structure c)
or Ge-O3 (structure d ) coordination bonds are broken
(Figure 3). Rupture of the Ge-N coordination bond in

New Stable Germylenes
Organometallics, Vol. 22, No. 26, 2003 5445
F igu r e 4. Shape of frontier molecular orbitals (HOMO and LUMO) in 1a and 1c.
,3b GeCl
‚dioxane,16 Et
SnOAc,17 Ge(SBu) ,5
3 2
Ta ble 6. F r on tier Or bita l En er gies (eV) of 1a ,c a n d
GeOCH
and Me
2
3
CH
2
NMe
2
2
SiSBu18 were synthesized as discribed earlier. The
2
a ,c,d
solvents commercially available were purified by conventional
methods and distilled immediately prior to use. NMR spectra
orbital
1a
1c
2a
2c
2d
LUMO
HOMO
HOMO-1
-1.27
-5.66
-6.06
-3.06
-4.93
-6.55
-0.79
-5.13
-5.93
-1.64
-4.62
-6.09
-1.28
-5.38a
-5.82
1
were recorded at 360.13 and 300.13 MHz ( H) and 90.55 and
a
a
1
3
7
5.47 MHz ( C) for the samples in CD
2 2 8
Cl and THF-d .
a
a
Chemical shifts are relative to SiMe for H, C or indirectly
4
a
Lone electron pair on Ge atom.
referenced to TMS via the solvent signals. Accuracy of the
coupling constant determination is (0.1 Hz; accuracy of the
The energies of molecular orbitals of LEP of metal
atoms decrease in the order 2a > 1a > 2d > 2c > 1c
Table 6). The loss of coordination at the Ge atom results
1
chemical shift measurements is (0.01 ppm ( H) and (0.05
1
3
ppm ( C).
(
2 2 2 2 2 2 2
ClGeOCH CH NMe (1). A solution of Ge(OCH CH NMe )
in the lowering of LEP energy. We can conclude from
the data presented that germylene 2 should be more
nucleophilic than 1.
(0.6729 g, 2.71 mmol) in THF (10 mL) was added at room
temperature to a stirred solution of GeCl
2
‚D (4) (0.6268 g, 2.71
mmol) in THF (30 mL). The mixture was refluxed for 0.5 h.
3
The filtered solution was reduced in volume to about 10 cm
Calculated charge distributions in isomers 1(2)a , b,
c, d (Figure 3) show an increase of the positive charge
on the Ge atom and negative charge on the N atom with
the rupture of the Ge-N coordination bonds (transitions
and kept at -12 °C to give white crystals of 1. Yield: 0.79 g
(
74%); mp 74-75 °C with dec (in a sealed capillary). Anal.
Calcd for C
C, 25.05; H, 5.23. H NMR (CD
b, t, 2H, CH N), 4.23 (t, 2H, CH O, J ) 5.7 Hz). C NMR
4
H10ClGeNO: C, 24.49; H, 5.14; Cl, 18.07. Found:
1
2
Cl
2
2
): δ 2.69 (s, 6H, Me N, 2.96
1
(2)a f 1(2)c). Transition 2a f 2d leads to an increase
3
13
(
2
2
of the negative charge on the O(3) atom. Changes in
charges on the O(1) and O(2) atoms are insignificant.
(CD Cl ): δ 45.88 (Me N), 61.32 (CH N), 67.8 (br, CH O).
2
2
2
2
2
AcOGeOCH
2
CH
2
NMe
2
(2). Et
3
GeOCH
2
CH
2
NMe
2
(3.6355
g, 14.68 mmol) was added at room temperature to a stirred
solution of Ge(OAc) (5) (2.81 g, 14.74 mmol) in THF (50 mL).
The mixture was refluxed for 0.5 h. The solvent was removed
in vacuo, the residue was evaporated at 50-60 °C/1 Torr, and
the volatiles were condensed in a liquid nitrogen cooled trap.
2
Con clu sion
Data presented above show that one coordination
GerN bond and two electronegative groups at the Ge-
II) atom provide enough stabilization to make possible
the existence of monomeric Ge(II) organic derivatives
without steric protection of the Ge atom by bulky
substituents. This fact opens new opportunities in the
synthesis of stable, monomeric germylenes and related
compounds.
The resulting crude product was crysrallized from THF/Et
at -12 °C, giving 2 as white crystals. Yield: 2.15 g (66.8%);
13
mp 67-68 °C (in a sealed capillary). Anal. Calcd for C H -
2
O
(
6
1
GeNO
CD Cl
t, 2H, CH
Cl ): δ 23.36 (MeCO), 44.19 (Me
O), 177.01 (CdO).
3
: C, 32.79; H, 5.96. Found: C, 33.04; H, 6.12. H NMR
(
2
2
): δ 1.93 (s, 3H, MeCO), 2.63 (s, 6H, Me N), 2. 84 (b,
2
3
13
2
N), 4.11 (t, 2H, CH
2
O, J ) 5.7 Hz). C NMR (CD
2
-
2
2
N), 60.50 (CH N)), 64.60 (b,
2
CH
2
Exp er im en ta l Section
(16) Fjeldberg, T.; Haaland, A.; Schilling, B. E. R.; Lappert, M. F.;
Thorne, A. J . Chem. Soc., Dalton Trans. 1986, 1551.
17) Ingham, R. K.; Rosenberg, S. D.; Gilman, H. Chem. Rev. 1960,
Gen er a l P r oced u r es. All manipulations were carried out
(
under purified argon atmosphere using standard Schlenk and
6
0, 459.
3
b
high-vacuum-line techniques. Ge(OCH
2
CH
2
NMe
2
)
2
,
Et
3
-
(18) Schmeisser, M.; Miller, H. Angew. Chem. 1957, 69, 781.

5
446 Organometallics, Vol. 22, No. 26, 2003
Zemlyansky et al.
Ge(OAc)
mmol) in Et
temperature to a stirred solution of GeCl
mmol) in Et O/THF (50 mL). After 30 min the solvent was
removed by distillation at normal pressure until the vapor
temperature increased to 70 °C. The residue was evaporated
at 100 °C/1 Torr. The volatiles were condensed in a liquid
nitrogen cooled trap. The oil residue was treated with ether,
and the precipitate was filtered off, washed, and dried in vacuo.
The yield of 5 as a white solids is 2.22 g (60%); mp 109-110
2
(5). (a) A solution of Et
O/THF (50 mL) (in ratio 1:1) was added at room
‚D (4) (4.49 g, 19.4
3
SnOAc (10.26 g, 38.8
methods and by full-matrix least-squares refinement with
anisotropic thermal parameters for non-hydrogen atoms. The
hydrogen atoms in 1 were objectively localized in the difference
Fourier map and refined isotropically. The hydrogen atoms
in 2 were placed in calculated positions and refined in a riding
model with fixed thermal parameters. All calculations were
carried out by use of the SHELXTL PLUS (PC Version 5.0)
program.20 Crystallographic data for 1 and 2 have been
deposited with the Cambridge Crystallographic Data Center,
CCDC nos. 206357 and 206358, respectively. Copies of this
information may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax +44
2
2
2
°C (in a sealed capillary). Anal. Calcd for C
4 6 4
H GeO : C, 25.20;
H, 3.17. Found: C, 25.43; H, 3.09. Distillation of liquid
1
223 336033; e-mail deposit@ccdc.cam.ac.uk or www.ccdc.ca-
1
collected in the trap gave 8.21 g (87.8%) of Et
3
SnCl. 5: H NMR
CH ) 128.1 Hz); C NMR (C N) δ
3.24 (Me); 177.24 (CdO).
b) A solution of Et SnOAc (6.88 g, 26 mmol) in THF (50
mL) was added at room temperature to a stirred solution of
Ge(SBu) (3.255 g, 13 mmol) in THF (20 mL). After 20 min
stirring the reaction mixture was worked up as in procedure
a). The yield of 5 is 6.1 g (90%), mp 109-110 °C (in a sealed
m.ac.uk).
1
13
(
C
5
D
5
N) δ 2.03 (Me,
J
5 5
D
2
Ack n ow led gm en t. This work was financially sup-
ported by the Russian Foundation for Basic Research
Projects Nos. 00-03-32889a, 00-03-32807a, 00-15-97359)
(
3
(
2
and by the Russian Academy of Sciences based on the
subprogram “Theoretical and experimental study of
chemical bonding and mechanisms of chemical reactions
and processes”. We thank Dr. M. G. Kuznetsova for
providing us with multinuclear NMR measurements.
(
capillary). A mixture of the probe and the substance obtained
by procedure (a) melts without decomposition.
Rea ction of Ge(OAc)
0.6108 g, 3.21 mmol) was dissolved in Me
2
w ith Me
3
SiSBu . Solid Ge(OAc)
SiSBu (1.86 g, 11.5
2
(
3
Su p p or tin g In for m a tion Ava ila ble: Tables of atom
coordinates, bond lengths and angles, and anisotropic dis-
placement parameters for 1 and 2. This material is available
free of charge via the Internet at http://pubs.acs.org.
mmol). This operation is exothermic. After that the reaction
mixture was heated to boiling for 15 min and volatiles were
-
3
2
evaporated in vacuo at 10 Torr. Ge(SBu) (0.802 g, 99.9%)
was obtained as a residue. NMR spectra of the substance were
identical to those of the compound described previously.5
OM034068+
X-r a y Str u ctu r e Deter m in a tion . Data were collected on
a Bruker SMART CCD 1000 diffractometer and corrected for
Lorentz and polarization effects and for absorption.19 For
details see Table 2. The structures were determined by direct
(
19) Sheldrick, G. M. SADABS, V2.01, Bruker/Siemens Area Detec-
tor Absorption Correction Program; Bruker AXS: Madison, WI, 1998.
20) Sheldrick, G. M. SHELXTL, V5.10; Bruker AXS Inc.: Madison,
WI 53719, 1997
(