Synthesis and structures of [{HC(CMeNAr)2}Ge(S)X] (Ar = 2,6-iPr2C6H3, X = F, Cl, Me): Structurally characterized examples with a formal double bond between group 14 and 16 elements bearing a halide

Article abstract of DOI:10.1021/ja017645z

Treatment of [{HC(CMeNAr)₂}GeX] (Ar = 2,6-iPr₂C₆H₃, X = Cl (1), F (2)), with elemental sulfur at room temperature smoothly afforded the [{HC(CMeNAr)₂}Ge(S)X] (X = Cl (3), F (4)). Compound 4 can also b

Full text of DOI:10.1021/ja017645z

Published on Web 06/28/2002
Synthesis and Structures of [{HC(CMeNAr)2}Ge(S)X] (Ar ) 2,6-iPr2C6H3, X )
F, Cl, Me): Structurally Characterized Examples with a Formal Double Bond
between Group 14 and 16 Elements Bearing a Halide
Yuqiang Ding, Qingjun Ma, Isabel Uso´n, Herbert W. Roesky,* Mathias Noltemeyer, and
Hans-Georg Schmidt
Institut fu¨r Anorganische Chemie der UniVersita¨t Go¨ttingen, Tammannstrasse 4, D-37077 Go¨ttingen, Germany
Received November 30, 2001
Scheme 1
Species containing multiple bonded heavier main group elements
are important precursors for a variety of new reactions. Especially
of great interest are compounds with halides, where the halides
can easily be replaced to synthesize a plethora of new compounds.
Over the past few decades, the double bonds between heavier main
group elements had been considered to be unstable due to their
weak π-bonds. However, in 1981, compounds with SidC1, Sid
Si2, and PdP3 bonds were prepared by taking advantage of the
protection from the bulky ligands. After that, remarkable progress
has been made in the chemistry of multiple bonded compounds of
heavier main group elements. In recent years, interest in the
chemistry of double bonded species between group 14 and 16
heavier elements M ) E (M ) Si, Ge, Sn; E ) S, Se, Te), analogues
of ketone, has remarkably increased.4 Examples such as Si (E )
S),5 Ge (E ) S, Se, Te),6-12 and Sn (E ) S, Se, Te)13 have been
synthesized and structurally characterized. In contrast, the chemistry
1
analysis, EI-MS, H, and 19F NMR. All results are in accord with
the corresponding formula.17
of compounds involving multiply bonded elements bearing halides
The solid-state structures of 3, 4, and 5 were determined by
was neglected; only one example was recently reported without
single-crystal X-ray diffraction. Compound 3 crystallizes in the
structural investigation.14 We were interested in the preparation of
P21/c space group, while 4 and 5 crystallize in the space group
the heavier chalcogen analogues of alkanoyl halide M(Cl) ) E, as
P21/n.18 The structures of 3, 4, and 5 are shown in Figures 1-3.
potentially important precursors, for the synthesis of compounds
Selected bond lengths and bond angles are given in the legends.
containing double bonded heavier main group elements. The
Figures 1-3 show that compounds 3-5 are monomeric. The
preparation of a stable germanium (II) chloride, [{HC(CMeNAr)2}-
germanium centers adopt four coordinated geometries and reside
GeCl] (Ar ) 2,6-iPr2C6H3 (1)),15 and its conversion to the
in a distorted tetrahedral environment.
structurally characterized germanium (II) hydride and fluoride
The Ge-S bond length (2.053(6) Å in 3, 2.050(9) Å in 4, and
[{HC(CMeNAr)2}GeF] (2)16 prompted us to study the synthesis
2.104(7) Å in 5), which is shorter than the Ge-S single bond length
of RGedS(X) compounds. Herein, we report on the synthesis of
(2.239(1) Å),11 is in agreement with those (2.063(3) Å6 and 2.045-
[{HC(CMeNAr)2}Ge(S)X] (Ar ) 2,6-iPr2C6H3, X ) Cl (3), F (4),
(3) Å12) reported for GedS. The Ge-S bond length in 3 (2.053(6)
Me (5)) as well as their solid structures.
Å) is comparable to that in 4 (2.050(9) Å) but distinctly shorter
Treatment of 1 with elemental sulfur in toluene at ambient
(0.051 Å) than that of 5 due to the difference of the electron-
temperature for 2 days smoothly afforded [{HC(CMeNAr)2}Ge-
(S)Cl] (Ar ) 2,6-iPr2C6H3 (3)) in excellent yield (0.49 g, 88%)
(Scheme 1). Slightly yellow crystals of 3 were obtained from a
withdrawing ability among F, Cl, and Me. This property also
influences the average Ge-N bond length (4 (1.888 Å) < 3 (1.895
Å) < 5 (1.941 Å)). The Ge-Cl bond length in 3 (2.195(7) Å) is
toluene solution at -32 °C. The fluoro analogue [{HC(CMeNAr)2}-
0.10 Å shorter than that in the starting material 1 (2.295(1) Å) as
Ge(S)F] (4), which is expected to have a different reactivity due to
expected for the higher oxidation state of the product. The Ge-F
the strong electron-withdrawing property compared to those of other
bond length in 4 (1.848(2) Å) is in the expected range (1.781(10)19
halides, can be generated by two routes: from 3 by the fluorination
to 1.867(14) Å20).
with Me3SnF or from 2 by the oxidative addition of elemental sulfur
(Scheme 1). Both methods yield colorless crystals from toluene
solutions. The reactivity of 3 was preliminarily checked by using
the smallest alkylation reagent MeLi (Scheme 1). Treatment of 3
with MeLi led to the formation of [{HC(CMeNAr)2}Ge(S)Me] (5).
The thus-far known structurally characterized double bonded heavier
main group elements are bound to bulky ligands. With this reaction
a small alkyl group was introduced into such a system for the first
The geometries as well as the Ge-S bond length of 3, 4, and 5
are very close to those of the compounds containing terminal
chalcogenido germanium units.6,10 The compounds reported are
stabilized by intramolecular coordination of a base shown by the
resonance structure in Scheme 2.6 The short Ge-S bond length in
compounds 3, 4, and 5 is indicative for a double bond or a Ge-S
σ bond with an additional percentage of ionic character. The Ge-
Cl bond may also influence the Ge-S bond. For discussion of the
double bond character, compound [Ge(Cl){C6H3-2,6-Mes2}]221 may
be used. In this compound, the multiple character of the Ge-Ge
time. Compounds 3, 4, and 5 were characterized by elemental
* To whom correspondence should be addressed. E-mail: hroesky@gwdg.de.
9
8542
J. AM. CHEM. SOC. 2002, 124, 8542-8543
10.1021/ja017645z CCC: $22.00 © 2002 American Chemical Society

C O M M U N I C A T I O N S
Supporting Information Available: The detailed synthetic pro-
cedures, analytical and spectral characterization data (PDF). X-ray
crystallographic files (CIF) for 3, 4, and 5. This material is available
free of charge via the Internet at http://pubs.acs.org.
References
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Figure 1. Molecular structure of 3 in the crystal (50% probability thermal
ellipsoids). Selected bond lengths (Å) and angles (deg): Ge(1)-Cl(1) 2.195-
(7), Ge(1)-S(1) 2.053(6), Ge(1)-N(1) 1.881(1), Ge(1)-N(2) 1.910(1);
S(1)-Ge(1)-N(1) 118.87(4), S(1)-Ge(1)-N(2) 118.33(4), S(1)-Ge(1)-
Cl(1) 116.82(2), N(1)-Ge(1)-N(2) 98.18(6), Cl(1)-Ge(1)-N(1) 99.51-
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Figure 2. Molecular structure of 4 in the crystal (50% probability thermal
ellipsoids). Selected bond lengths and angles (deg): Ge(1)-F(1) 1.848(2),
Ge(1)-S(1) 2.050(9), Ge(1)-N(1) 1.892(2), Ge(1)-N(2) 1.884(2); S(1)-
Ge(1)-N(1) 120.14(7), S(1)-Ge(1)-N(2) 119.58(7), S(1)-Ge(1)-F(1)
116.57(8), N(1)-Ge(1)-N(2) 97.69(10), F(1)-Ge(1)-N(1) 99.07(9), F(1)-
Ge(1)-N(2) 99.61(9).
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Organometallics 2001, 20, 4806.
(17) The physical data of 3, 4, and 5 are given in the Supporting Information.
(18) The structures were solved by direct methods (SHELXS-97) and refined
against F2 using SHELXL-97.22 All non-hydrogen atoms were refined
anisotropically. All hydrogen atoms were included in the refinement in
geometrically ideal positions. (a) Crystallographic data for 3:
C29H41-
ClGeN2S, Mr ) 557.74, crystal size: 0.25 × 0.13 × 0.13 mm3, monoclinic,
space group P21/c, a ) 16.880(3) Å, b ) 13.044(3) Å, c ) 13.801(3) Å,
R ) γ ) 90°, â ) 108.57(3)°, V ) 2880.5(10) Å3, Z ) 4, Fcalcd ) 1.286
Mgm-3, F(000) ) 1176, T ) 133(2) K, µ (Mo KR) ) 1.248 mm-1, 2.01°
e θ e 27.82°; of the 42179 reflections collected, 6747(Rint ) 0.0457)
were independent. The R values are R1 ) 0.0312 (I > 2σ (I)) and wR2
) 0.0721 (all data); max/min residual electron density: 0.355/-0.448 e
Å -3. (b) Crystallographic data for 4: C36H49FGeN2S incl.toluene, Mr )
633.42, crystal size: 1.00 × 0.40 × 0.40 mm3, monoclinic, space group
P21/n, a ) 13.467(2) Å, b ) 16.804(3) Å, c ) 15.668(3) Å, R ) γ )
Figure 3. Molecular structure of 5 in the crystal (50% probability thermal
ellipsoids). Selected bond lengths and angles (deg): Ge(1)-C(6) 2.009(2),
Ge(1)-S(1) 2.104(7), Ge(1)-N(1) 1.930(2), Ge(1)-N(2) 1.952(2); S(1)-
Ge(1)-N(1) 111.54(5), S(1)-Ge(1)-N(2) 110.41(5), S(1)-Ge(1)-C(6)
120.25(6), N(1)-Ge(1)-N(2) 94.15(10), C(6)-Ge(1)-N(1) 107.69(8),
C(6)-Ge(1)-N(2) 109.66(8).
90°, â ) 92.783(16)°, V ) 3541.5(11) Å3, Z ) 4, Fcalcd ) 1.188 Mgm-3
,
F(000) ) 1344, T ) 200(2) K, µ (Mo KR) ) 0.945 mm-1, 3.65° e θ e
25.13°; of the 9893 reflections collected, 6266 (Rint ) 0.0300) were
independent. The R values are R1 ) 0.0467 (I > 2σ (I)) and wR2 )
Scheme 2
0.1318 (all data); max/min residual electron density: 0.821/-0.736 eÅ-3
.
(c) Crystallographic data for 5: C30H44GeN2S, Mr ) 537.32, crystal size:
0.50 × 0.13 × 0.13 mm3, monoclinic, space group P21/n, a ) 12.663(3)
Å, b ) 19.441(4) Å, c ) 13.350(3) Å, R ) γ ) 90°, â ) 117.49°, V )
2915.4(10) Å3, Z ) 4, Fcalcd ) 1.224 Mgm-3, F(000) ) 1144, T )133(2)
K, µ (Mo KR) ) 1.142 mm-1, 2.71 e θ e 27.67°; of the 32774 reflections
collected, 6745 (Rint ) 0.0412) were independent. The R values are R1 )
0.0373 (I > 2σ(I)) and wR2 ) 0.1032 (all data); max./min. residual
bond is open to debate because of the significantly longer Ge-Ge
bond length compared to those of other digermenes.
In summary, compounds 3 and 4 are the structurally characterized
examples with a formal double bond between group 14 and 16
elements bearing a halide. The chemistry without degradation of
the GedS bond is shown by the metathesis reaction of 3 to 4 and
5.
electron density: 0.953/-1.063 eÅ-3
.
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1997, 16, 1920.
Acknowledgment. This work was supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
Dedicated to Professor R. Uso´n.
(22) Sheldrick, G. M. SHELXL-97 Universita¨t Go¨ttingen: Go¨ttingen,1997.
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