Hydrostannylation of ketones and alkynes with LSnH [L = HC(CMeNAr) 2, Ar = 2,6-/Pr2C6H3]

Article abstract of DOI:10.1021/ic9012069

The reactions of the stable β-diketiminate tin(II) hydride LSnH [L = HC(CMeNAr)₂, Ar = 2,6-/Pr₂C₆H₃] with different ketones (Ph₂CO, 2-Py₂CO, CyPr₂CO, and 2-C₄H₃

Full text of DOI:10.1021/ic9012069

Inorg. Chem. 2009, 48, 9543–9548 9543
DOI: 10.1021/ic9012069
Hydrostannylation of Ketones and Alkynes with LSnH [L = HC(CMeNAr)2,
Ar = 2,6-iPr2C6H3]
Anukul Jana,† Herbert W. Roesky,*,† and Carola Schulzke‡
::
:: ::
::
†Institut fur Anorganische Chemie, Universitat Gottingen, Tammannstrasse 4, 37077 Gottingen, Germany, and
‡School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
Received June 23, 2009
The reactions of the stable β-diketiminate tin(II) hydride LSnH [L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3] with different
ketones (Ph2CO, 2-Py2CO, cyPr2CO, and 2-C4H3SCOCF3) generated a variety of tin(II) alkoxides (1-4) in high yield.
The activated terminal alkynes (HCtCCO2R, R = Me, Et) react with LSnH to yield the tin(II) substituted terminal
alkenes (5-6) instead of dihydrogen elimination although the Sn-H and C-H bonds are differently polarized.
Furthermore, LSnH reacts with disubstituted alkyne (RO2CCtCCO2R, R = Et, tBu) in toluene at room temperature to
form the stannylene substituted internal alkenes (7-8). Compounds 1-8 were characterized by microanalysis and
multinuclear NMR spectroscopy. Moreover compounds 3, 4, 5, and 7 were characterized by X-ray crystallography, and
the resulting structures confirmed the monomeric nature, in which the tin centers reside in a trigonal-pyramidal
environment.
Introduction
lysts.1 In recent years the chemistry of stable heteroleptic
metal hydrides has attracted much attention because of their
versatile reactivity.2 In comparison with main group hydrides
the chemistry of transition metal hydrides is well documen-
ted.3 Organometallic hydrides of group 14 play an important
role in various metathesis reactions, and therefore the reac-
tivity of hydrides like R3SiH, R3GeH, and R3SnH is well
studied.4 In recent years the parent SnH2 has been prepared
and characterized in an argon matrix.5 At elevated tempera-
ture SnH2 changed to an insoluble solid of unknown struc-
ture. The terphenyl and β-diketiminate ligands have been
used for the preparation of substituted tin(II) hydrides. The
terphenyl derivatives show dimeric structures in the solid
state,6 while the β-diketiminate moiety exhibits a terminal
tin(II) hydride with very weak intermolecular interaction.7
Until recently the reactions of organotin hydrides were based
mainly on tin(IV) precursors. Di- and triorganotin hydrides
of composition R2SnH2 and R3SnH with formal oxidation
state of Sn(IV) show a rich variety of chemical transforma-
tions.8 The preferred reagent of this class of compounds is the
Metal hydrides and their complexes are considered valu-
able synthons in chemistry. It was demonstrated that main
group and transition metal hydrides are important inter-
mediates in industrial processes and also function as cata-
*To whom correspondence should be addressed. E-mail: hroesky@
gwdg.de. Fax: þ49-551-393373.
(1) (a) Kaesz, H. D.; Saillant, R. B. Chem. Rev. 1972, 72, 231–281.
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r
2009 American Chemical Society
Published on Web 09/08/2009
pubs.acs.org/IC

9544 Inorganic Chemistry, Vol. 48, No. 19, 2009
Scheme 1. Preparation of Compounds 1, 2, 3, and 4
Jana et al.
ppm).10 For the H NMR spectra of LSnOC(O)H, (δ 8.97
ppm)10 and LSnOCHPh(2-Py) (δ 6.28 ppm)10 we compared
the CH resonances with that of LSnH (δ 13.96 ppm). This
indicates the conversion of the tin(II)-hydride to the corre-
sponding tin(II)-alkoxide. The 119Sn NMR exhibits reso-
nances at -256 ppm and -324 ppm for compounds 1 and 2.
The two values are different because of the non identical
electronic nature of the phenyl rings when compared with
those of the 2-pyridyl rings. In the EI mass spectra the
molecular ion peaks were observed at m/z 719 and 722 as
the base peaks for 1 and 2.
Compound 3 has one CF3 group and displays an interest-
ing NMR spectrum. The 1H NMR spectrum of 3 exhibits a
quartet (δ 5.45 ppm) which corresponds to the quaternary
CH proton and its coupling with the three F-atoms of the CF3
group (3J(19F-1H) = 7 Hz). The 19F NMR resonance arises
as a doublet (δ -77.39 ppm) with the same coupling constant
of 6.99 Hz and is flanked by Sn satellite lines (4J(119Sn-1H) =
42 Hz). The four isopropyl groups of 3 show four dif-
ferent resonances, and even the two methyl groups in the
backbone exhibit two different signals in the 1H NMR
spectrum.
1
tributyltin hydride, and it is widely used as a reducing agent
in organic and inorganic chemistry.9 In a preliminary
publication we have shown some reactions of tin(II) hydride
with unsaturated molecules.10 There we describe the reaction
of LSnH [L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3] with
carbon dioxide, 2-benzoyl pyridine, 2,2,2-trifluoro acetophe-
none, ferrocene carbaldehyde, MeCtCO2Et, MeO2CCtC-
CO2Me, and dicyclohexyl carbodiimide. LSnH reacts with
alkynes under the formation of vinylated stannylenes. So far
we used no terminal alkynes, which might either eliminate
dihydrogen or undergo nucleophilic addition reaction to the
triple bond. Herein, we describe the hydrostannylation reac-
tions of a variety of ketones and alkynes with LSnH,
although Albertin et al. reported on the reactivity of tin(IV)
trihydride with terminal alkynes and carbon dioxide.11
At room temperature there is no reaction observable when
LSnH is treated with dicyclopropylketone in toluene. How-
ever, after refluxing this mixture for 12 h compound 4 is
formed in high yield. Compound 4 is composed of two
cyclopropyl rings, and to our surprise they were not decom-
Results and Discussion
1
LSnH was synthesized from the corresponding tin(II)
chloride, LSnCl12 with potassium triisobutylborohydride
(K[HB(iBu)3]) in toluene at -10 °C. The 1H NMR spectrum
of LSnH shows a low field singlet (δ 13.96 ppm) correspond-
ing to the proton of the Sn-bound hydrogen. The ketone
group and its transformation to other functional groups is
very important in organic chemistry.13 In the literature there
are numerous reports on hydrostannation reaction of ke-
tones using tin(IV) hydride.14
posed during the reaction. The H NMR spectrum of 4
exhibits a triplet (δ 2.47 ppm), which can be assigned to the
quaternary CH proton which is coupled by two C-H
protons from the two cyclopropyl rings with a coupling
constant of 7.3 Hz. In the 1H NMR spectrum of compound
4 the quaternary proton resonance arises upfield (δ 2.47
ppm), when compared with the corresponding proton signal
in compounds 1-3 (δ 6.28, 6.59, 5.45 ppm). This is mainly
due to the different electronic nature of the two cyclopropyl
rings in compound 4. The other protons of the cyclopropyl
rings show the expected resonances. The two quaternary CH
protons of the two cyclopropyl rings exhibit a multiplet each
at 0.75 ppm. The four CH2 groups of the two cyclopropyl
rings are not identical, they show four multiplets (δ 0.21, 0.02,
-0.07, -0.25 ppm). Each multiplet is not consistent with
each methylene group. It has been found that each multiplet
corresponds to one proton from each of the two cyclopropyl
rings.
Single crystals of 3 and 4 suitable for X-ray structural
analysis were obtained from n-hexane solutions. Both 3 and 4
crystallize in the triclinic space group P1 (Table 1). The
molecular structures of 3 and 4 are shown in Figures 1 and 2.
The asymmetric unit of 3 and 4 contains one formula unit of
the compound, and two of the molecules in each unit cell. As
predicted on the basis of the 1H NMR spectrum and the EI
mass spectrum, compounds 3 and 4 contain a Sn(II)-O-CH
core. The three coordinate tin atom is surrounded by two N
atoms of the β-diketiminato ligand, and an exocyclic O atom.
Treatment of LSnH with benzophenone, di(2-pyri-
dyl)ketone, 2,2,2-trifluoroacetothiophene, and dicyclopro-
pylketone leads quantitatively to the stannylene alkoxides
1, 2, 3, and 4, respectively, with a Sn(II)-O-C framework
that is formed by nucleophilic hydride addition to the
respective carbon of the carbonyl group (Scheme 1). Com-
pounds 1-4 were monitored by their 1H NMR spectra.
1
Sharp resonances in the H NMR of 1-4 gave the initial
indication that the products have been formed in high yield.
1
The H NMR spectra of 1 and 2 exhibit each an upfield
shifted singlet (δ 6.28, 6.59 ppm) for the quaternary CH
proton, when compared with that of LSnOC(O)H, (δ 8.97
(9) (a) Neumann, W. P. Synthesis 1987, 665–683. (b) Chen, L.; Cotton, F. A.;
Wojtczak, W. A. Inorg. Chim. Acta 1996, 252, 239–250.
::
(10) Jana, A.; Roesky, H. W.; Schulzke, C.; Doring, A. Angew. Chem.
2009, 121, 1126–1129. Angew. Chem., Int. Ed. 2009, 48, 1106-1109.
(11) (a) Albertin, G.; Antoniutti, S.; Bacchi, A.; Bortoluzzi, M.; Pelizzi,
G.; Zanardo, G. Organometallics 2006, 25, 4235–4237. (b) Albertin, G.;
ꢀ
Antoniutti, S.; Castro, J.; García-Fontan, S. G.; Zanardo, G. Organometallics
2007, 26, 2918–2930.
(12) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Organo-
metallics 2001, 20, 1190–1194.
(13) Katritzky, A. R. Comprehensive Organic Functional Transformations;
Elsevier Pergamon: Amsterdam, 1995.
(14) (a) Shibata, I.; Suzuki, T.; Baba, A.; Matsuda, H. J. Chem. Soc.,
Chem. Commun. 1988, 882–883. (b) Fisch, M. H.; Dannenberg, J. J.; Pereyre,
M.; Anderson, W. G.; Rens, J.; Grossman, W. E. L. Tetrahedron 1984, 40, 293–
298. (c) Clive, D. L. J.; Chittattu, G.; Wong, C. K. J. Chem. Soc., Chem.
Commun. 1978, 41–42. (d) He, A.; Falck, J. R. Angew. Chem. 2008, 120, 6586–
6589. Angew. Chem., Int. Ed. 2008, 47, 6688-6691.
˚
˚
The Sn-O bond lengths (2.046 A and 2.024 A) are compar-
15
˚
able with those of compound [LAl(Me)O]2Sn (1.9597 A).
The O-C bond distances of 3 and 4 are in a narrow range
of each other (1.418 A and 1.431 A). Furthermore com-
˚
˚
pounds 1-4 were characterized by elemental analysis, except
(15) Nembenna, S.; Singh, S.; Jana, A.; Roesky, H. W.; Yang, Y.; Ye, H.;
Ott, H.; Stalke, D. Inorg. Chem. 2009, 48, 2273–2276.

Article
Inorganic Chemistry, Vol. 48, No. 19, 2009 9545
Table 1. Crystallographic Data for the Structural Analyses of Compounds 3, 4, 5, and 7
3
4
5
7
empirical formula
CCDC-No.
T [K]
C
35H45 F3N2 OSSn
730402
C36H52N2OSn
730399
133(2)
triclinic
P1
9.0024(18)
12.105(2)
16.135(3)
76.66(3)
76.23(3)
84.38(3)
1660.0(5)
2
1.295
0.799
680
C33H46N2O2Sn
730401
133(2)
triclinic
P1
11.067(2)
12.259(3)
13.922(3)
115.84(3)
93.10(3)
108.12(3)
1575.4(6)
2
C37H52N2O4Sn
730400
133(2)
monoclinic
P21/c
14.806(3)
12.705(3)
19.471(4)
90
102.38(3)
90
3577.6(12)
4
1.314
0.753
1480
133(2)
triclinic
P1
crystal system
space group
˚
a [A]
8.8197(18)
12.061(2)
16.556(3)
81.07(3)
77.65(3)
87.01(3)
1699.2(5)
2
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
3
˚
V [A ]
Z
Dcalcd [g cm-3
]
1.402
0.859
740
1.310
0.841
648
μ [mm-1
F(000)
]
θ range [deg]
reflections collected/unique
1.71-26.99
16245/7340
[R(int) = 0.0384]
7340/0/401
0.0488, 0.1348
0.0595, 0.1401
1.044
2.33-27.12
14776/7075
[R(int) = 0.0762]
7075/0/379
0.0504, 0.1040
0.0797, 0.1104
0.884
1.67-26.96
14660/6731
[R(int) = 0.0322]
6731/0/358
0.0317, 0.0557
0.0429, 0.0576
1.052
1.41-26.97
22711/7419
[R(int) = 0.1288]
7419/0/413
0.0686, 0.0835
0.1449, 0.0999
0.983
data/restraints/parameters
R1, wR2 [I > 2σ(I)]a
R1, wR2 (all data) a
GoF
-3
˚
ΔF(max), ΔF(min) [e A
]
1.932, -1.712
2.206, -1.035
0.493, -1.147
1.274, -0.889
P
P
P
P
aR1 = ||Fo| - |Fc||/ |Fo|; wR2 = [ w(Fo2 - Fc2)2/ w(Fo2)2]0.5
.
˚
Figure 1. Molecular structure of 3. Selected bond lengths [A] and angles
[deg]; anisotropic displacement parameters are depicted at the 50%
probability level, and all restrained refined hydrogen atoms are omitted
for clarity: Sn1-O1 2.046(3), Sn1-N1 2.194(3), O1-C1 1.418(6);
N1-Sn1-N2 83.30(11), N1-Sn1-O1 93.04(12), Sn1-O1-C1 114.5(4).
˚
Figure 2. Molecular structure of 4. Selected bond lengths [A] and angles
[deg]; anisotropic displacement parameters are depicted at the 50%
probability level, and all restrained refined hydrogen atoms are omitted
for clarity: Sn1-O1 2.024(3), Sn1-N1 2.199(4), O1-C1 1.431(6);
N1-Sn1-N2 82.79(14), N1-Sn1-O1 95.80(13), Sn1-O1-C1 117.5(3).
“carbon” in compounds 1 and 4; all the data are in good
agreement with the calculated one. This error may be due to
the unwanted impurities, although these are in the accepted
experimental range.
Scheme 2. Preparation of Compounds 5 and 6
The hydrostannation of alkynes is well-known since nearly
50 years ago, and follows a polar or a free radical pathway
depending on substituents, catalyst, solvent, and condi-
tions.16 In contrast to this result the present hydrostannyla-
tion reaction of alkynes with LSnH proceeds without any
catalyst. LSnH reacts with HCtCCO2Me and HCtCCO2Et
respectively at room temperature to form the vinyl stanny-
lenes 5 and 6 (Scheme 2).
5 and 6 are obtained by the 1,2-addition of stannylene
hydride LSnH to the terminal alkynes, and the result is the
transfer of the hydrogen atom and stannylene to the carbon
carbon triple bond (Scheme 2), rather than the elimination
(16) (a) Davies, A. G.; Smith, P. J. Comprehensive Organometallic
Chemistry; Pergamon: Oxford, U.K., 1982; Vol. 2, pp 584-591. (b) Davies,
A. G. Comprehensive Organometallic Chemistry II; Pergamon: Oxford, U.K.,
1995; Vol. 2, pp 270-277.

9546 Inorganic Chemistry, Vol. 48, No. 19, 2009
Jana et al.
˚
Figure 4. Molecular structure of 7. Selected bond lengths [A] and angles
˚
Figure 3. Molecular structure of 5. Selected bond lengths [A] and angles
[deg]; anisotropic displacement parameters are depicted at the 50%
probability level, and all restrained refined hydrogen atoms are omitted
for clarity: Sn1-C1 2.241(2), Sn1-N1 2.202(2), C1-C3 1.488(3);
N1-Sn1-N2 85.64(7), N1-Sn1-C1 93.06(8), Sn1-C1-C3 116.79(17).
[deg]; anisotropic displacement parameters are depicted at the 50%
probability level. Isopropyl groups and all restrained refined hydrogen
atoms are omitted for clarity: Sn1-N1 2.207(5), Sn1-C4 2.330(8),
C4-C5 1.331(9); N1-Sn1-N2 85.19(17), N1-Sn1-C4 92.3(2),
Sn1-C4-C5 121.5(5).
-211 ppm, for E- and Z-isomers of 7 and the resonance at
δ -123 and -205 ppm for E- and Z- isomers of 8.
The colors of 7 and 8 are yellow and red, respectively, in the
solid state and in solution. 7 and 8 are soluble in benzene,
THF, n-hexane, and n-pentane and show no decomposition
on exposure to air.
Scheme 3. Preparation of Compounds 7 and 8
7 crystallizes in the monoclinic space group P21/c, with one
monomer in the asymmetric unit from saturated n-hexane
solution at -32 °C after 1 day (Figure 4). In the crystalline
state we were only able to isolate the Z-isomer.
of H2 although the Sn-H and C-H bonds are differently
polarized.
Summary and Conclusion
5 and 6 are yellow solids soluble in benzene, THF, n-
hexane, and n-pentane and show no decomposition on
exposure to air. 5 and 6 were characterized by multinuclear
NMR and IR spectroscopy, EI mass spectrometry, and
elemental analysis. Furthermore 5 was characterized by
X-ray structural analysis (Figure 3). The 1H NMR spectrum
of 6 exhibits two broad resonances (δ 6.25 and 5.85 ppm)
which correspond to the two alkenyl protons. Moreover, the
1H NMR spectrum shows a quartet and a triplet resonance
(δ 4.07 and 0.87 ppm) corresponding to the two different
types of CH protons of the ethyl moieties. Compound
5 crystallizes in the triclinic space group P1, with one
monomer in the asymmetric unit, and with two molecules
in each unit cell. Single crystals were obtained from a
saturated n-hexane solution at -32 °C after 2 days
(Table 1). The coordination polyhedron around the tin atom
features a distorted tetrahedral geometry with a stereoche-
mically active lone pair.
Furthermore we were interested in the selectivity of the
addition across the carbon carbon triple bond. Therefore we
selected the disubstituted alkynes, diethyl acetylenedicarbox-
ylate and ditertiarybutyl acetylenedicarboxylate. LSnH re-
acts with dialkyl acetylenedicarboxylate, (RO2CCtCCO2R,
R = Et, tBu) in toluene at room temperature to form the two
isomers with E- and Z- stannylene substituted alkene in a
different ratio (1.00:0.69 for 7 and 1.00:1.52 for 8) (Scheme 3).
The 1H NMR spectra of 7 and 8 exhibittwo singlets which are
arranged betweenthe tin satellites with two different coupling
constants. The 119Sn NMR resonances arise at δ -130 and
Tin(II)-alkoxides have been prepared by the reaction of a
tin(II)-hydride with a variety of ketones resulting in com-
pounds containing the Sn(II)-O-CH core. Furthermore
tin(II)-hydride reacts with terminal and internal alkynes
generating the vinyl substitutedstannylene, rather than under
elimination of dihydrogen in the case of terminal alkynes.
Compounds 1-8 represent a unique new class of stannylene
compounds with an electron lone pair on tin(II) that is
primed for complexation reaction with transition metal
fragments. Moreover it is interesting to mention that most
of the compounds are stable in air and moisture and highly
soluble in common organic solvents.
Experimental Section
General Considerations. All manipulations were performed in
a dry and oxygen-free atmosphere (N2 or Ar) by using Schlenk-
line and glovebox techniques. Solvents were purified with the M-
Braun solvent drying system. Compound LSnH was prepared
by literature procedure.10 Other chemicals were purchased
commercially and used as received.1H, 13C, 19F, and 119Sn
NMR spectra were recorded on a Bruker 500 MHz instrument
and referenced to the deuterated solvent in the case of the 1H and
13C NMR spectra. 19F NMR spectra were referenced to CFCl3
and those of 119Sn NMR to SnMe4. Elemental analyses were
::
performed by the Analytisches Labor des Instituts fur Anorga-
nische Chemie der Universitat Gottingen. Mass spectra were
::
::
obtained on a Finnigan Mat 8230 instrument. Melting points
were measured in a sealed glass tube with a Buchi melting point
B 540 instrument and are not corrected.
::

Article
Synthesis of [{HC(CMeNAr)2}SnOCHPh2] (Ar = 2,6-iPr2-
Inorganic Chemistry, Vol. 48, No. 19, 2009 9547
1.00 mmol in 5 mL of toluene) was added by cannula to a
solution of LSnH (0.54 g, 1.00 mmol in toluene 20 mL) at room
temperature. After that the solution was heated under reflux for
12 h. Then all volatiles were removed from the solution in vacuo,
and the remaining residue was extracted with n-hexane (25 mL).
The solution was concentrated and stored in a freezer, after 4
days yellow crystals of 4 are formed which are suitable for X-ray
structural analysis. Yield (0.480 g, 74%); mp 169 °C; 1H NMR
(500 MHz, C6D6): δ 7.06-7.20 (m, 6 H, Ar-H), 4.71 (s, 1H, γ-
CH), 3.81 (sept, 2H, CH(CH3)2), 3.24 (sept, 2H, CH(CH3)2),
2.47 (q, 3J(H-H) = 7.3 Hz, 1H, CH), 1.58 (s, 6H, CH3), 1.52 (s,
6H, CH3), 1.28 (d, 6H, CH(CH3)2), 1.24 (d, 6H, CH(CH3)2),
1.14 (d, 6H, CH(CH3)2), 0.75 (m, 2H, CH), 0.21 (m, 2H, CH2),
0.02 (m, 2H, CH2), -0.07 (m, 2H, CH2), -0.25 (m, 2H, CH2)
ppm; 119Sn{1H} NMR (186.46 MHz): δ -190.50 ppm; EI-MS
(70 eV): m/z (%): 648 (100) [M]þ; elemental analysis (%) anal.
calcd for C36H52N2OSn (648.31): C, 66.78; H, 8.09; N, 4.33.
Found: C, 65.19; H, 8.00; N, 4.13.
C6H3) (1). A solution of Ph2CO (0.180 g, 1.00 mmol in 5 mL of
toluene) was added by cannula to a solution of LSnH (0.54 g,
1.00 mmol in toluene 20 mL) at room temperature. After 12 h all
volatiles were removed from the solution in vacuo, and the
remaining residue was extracted with n-hexane (25 mL) and
concentrated to about 15 mL and stored in a -30 °C freezer.
After 4 days yellow crystals of 1 are formed. Yield (0.590 g,
82%); mp 76 °C; 1H NMR (500 MHz, C6D6): δ 6.86-7.70 (m,
16H, Ar-H), 5.97 (s, 1H, CH), 4.80 (s, 1H, γ-CH), 3.67 (sept,
3J(H-H) = 6.50 Hz, 2H, CH(CH3)2), 3.15 (sept, 3J(H-H) =
6.50 Hz, 2H, CH(CH3)2), 1.57 (s, 6H, CH3), 1.19 (d, 3J(H-H) =
3
6.50 Hz, 6H, CH(CH3)2), 1.14 (d, J(H-H) = 6.50 Hz, 6H,
CH(CH3)2), 1.12 (d, 3J(H-H) = 6.50 Hz, 6H, CH(CH3)2), 1.07
(d, 3J(H-H) = 6.50 Hz, 6H, CH(CH3)2); 13C{1H} NMR
(125.77 MHz, C6D6): δ 165.22 (CN), 148.76-123.54 (Ar-C),
97.78 (γ-C), 78.87 (HC), 31.92, 28.58, 28.46, 26.32, 24.75, 24.71,
24.65, 24.46, 23.48, 23.42, 23.01 ppm; 119Sn{1H} NMR (186.46
MHz): δ -218 ppm; EI-MS (70 eV): m/z (%): 719 (100) [M]þ;
elemental analysis (%) anal. calcd for C42H52N2OSn (719.59):
C, 70.10; H, 7.28; N, 3.89. Found: C, 72.71; H, 7.53; N, 3.32.
Synthesis of [{HC(CMeNAr)2}SnOCH(2-Py)2] (Ar = 2,6-
iPr2C6H3) (2). A solution of (2-Py)2CO (0.185 g, 1.00 mmol in
5 mL of toluene) was added by cannula to a solution of LSnH
(0.54 g, 1.00 mmol in toluene 20 mL) at room temperature. After
overnight stirring all volatiles were removed from the solution in
vacuo, and the remaining residue was extracted with n-hexane
(25 mL). The solvent from the solution was completely removed
and compound 2 was obtained as a powder. Yield (0.560 g,
78%); mp 160 °C; 1H NMR (500 MHz, C6D6): δ 6.38-7.60 (m,
14H, Ar-H), 6.59 (s, 1H, CH), 4.85 (s, 1H, γ-CH), 3.93 (sept,
3J(H-H) = 6.85 Hz, 2H, CH(CH3)2), 3.55 (sept, 3J(H-H) =
6.85 Hz, 2H, CH(CH3)2), 1.72 (s, 6H, CH3), 1.44 (d, 3J(H-H) =
Synthesis of [{HC(CMeNAr)2}SnC(CO2Me)CH2] (Ar = 2,6-
iPr2C6H3) (5). A solution of methyl propiolate (0.085 g, 1.00
mmol in 5 mL of toluene) was added drop by drop by cannula to
a solution of LSnH (0.540 g, 1.00 mmol in toluene 15 mL) at
room temperature. After 0.5 h under constant stirring at ambi-
ent temperature all volatiles were removed from the solution in
vacuo, and the remaining residue was extracted with n-hexane
(15 mL) and concentrated to about 5 mL and stored in a -30 °C
freezer. Yellow crystals of 5 suitable for X-ray diffrac-
tion analysis are formed after 2 days. Yield: 0.435 g (70%);
mp 170 °C. 1H NMR (500 MHz, C6D6): δ 7.08-7.14 (m, 6H, Ar-
H), 6.45 (br, 1H, CdCH2), 6.15 (br, 1H, CdCH2), 4.81 (s, 1H,
γ-CH), 3.67 (sept, 2H, CH(CH3)2), 3.42 (s, 3H, CH3), 3.40 (sept,
2H, CH(CH3)2), 1.60 (s, 6H, CH3), 1.27 (m, 12H, CH(CH3)2),
1.16 (m, 12H, CH(CH3)2) ppm; 119Sn{1H} NMR (186.46 MHz):
δ -93.28 ppm. EI-MS: m/z (%) 622 (100) [M]þ. Elemental
analysis (%) anal. calcd for C33H46N2O2Sn (622.26): C, 63.78;
H, 7.46; N, 4.51. Found: C, 63.80; H, 7.84; N, 4.47.
3
6.85 Hz, 6H, CH(CH3)2), 1.23 (d, J(H-H) = 6.85 Hz, 6H,
CH(CH3)2), 1.17 (d, 3J(H-H) = 6.85 Hz, 6H, CH(CH3)2), 0.90
(d, 3J(H-H) = 6.85 Hz, 6H, CH(CH3)2) ppm; 13C{1H} NMR
(125.77 MHz, C6D6): δ 165.33, 164.43 (CN), 146.64-121.16
(Ar-C), 95.36 (γ-C), 79.86 (CH), 28.60, 28.44, 26.60, 24.88,
24.84, 24.60, 23.67 ppm; 119Sn{1H} NMR (186.46 MHz):
δ -324 ppm; EI-MS (70 eV): m/z (%): 722 (100) [M]þ; elemental
analysis (%) anal. calcd for C40H50N4OSn (722.30): C, 66.58; H,
6.98; N, 7.76. Found: C, 66.74; H, 6.94; N, 7.67.
Synthesis of [{HC(CMeNAr)2}SnC(CO2Et)CH2] (Ar = 2,6-
iPr2C6H3) (6). A solution of ethyl propiolate (0.100 g, 1.00 mmol
in 5 mL of toluene) was added drop by drop by cannula to a
solution of LSnH (0.490 g, 1.00 mmol in toluene 15 mL) at room
temperature. After 0.5 h under constant stirring at ambient
temperature the yellow solution remains unchanged. All vola-
tiles were removed from the solution in vacuo, and the remain-
ing residue was extracted with n-hexane (15 mL) and
concentrated to about 5 mL and stored in a -30 °C freezer.
Yellow crystals of 6 are formed after 1 week. Yield: 0.460 g
(72%); mp 168 °C. 1H NMR (500 MHz, C6D6): δ 7.10-7.20 (m,
6H, Ar-H), 6.70 (br, 1H, CdCH2), 6.10 (br, 1H, CdCH2), 4.82
(s, 1H, γ-CH), 4.08 (q, 2H, CH2), 3.67 (sept, 2H, CH(CH3)2),
3.42 (sept, 2H, CH(CH3)2), 1.62 (s, 6H, CH3), 1.28 (m, 12H,
CH(CH3)2), 1.18 (m, 12H, CH(CH3)2), 1.03 (t, 3H, CH2CH3)
ppm; 119Sn{1H} NMR (186.46 MHz): δ -89.02 ppm. EI-MS: m/
z (%) 636 (100) [M]þ. Elemental analysis (%) anal. calcd for
C34H48N2O2Sn (636.27): C, 64.26; H, 7.61; N, 4.41. Found: C,
63.98; H, 7.92; N, 4.38.
Synthesis of [{HC(CMeNAr)2}SnOCH(2-C4H3S)CF3] (Ar =
2,6-iPr2C6H3) (3). A solution of 2,2,2-trifluoroacetothiophene
(0.180 g, 1.00 mmol in 5 mL of toluene) was added by cannula to
a solution of LSnH (0.54 g, 1.00 mmol in toluene 20 mL) at room
temperature. After 12 h all volatiles were removed from the
solution in vacuo, and the remaining residue was extracted with
n-hexane (25 mL). The resulting solution was concentrated and
stored in a freezer, after 3 days yellow crystals of 3 are formed
which are suitable for X-ray structural analysis. Yield (0.610 g,
85%); mp 158 °C; 1H NMR (500 MHz, C6D6): δ 7.03-7.20 (m,
6H, Ar-H), 6.81 (m, 2H, C4H3S), 6.64 (m, 1H, C4H3S), 5.44 (q,
3J(F-H) = 6.99 Hz, 1H, CH), 4.87 (s, 1H, γ-CH), 3.78 (sept,
3J(H-H) = 6.50 Hz, 1H, CH(CH3)2), 3.61 (sept, 3J(H-H) =
6.50 Hz, 1H, CH(CH3)23), 3.30 (sept, 3J(H-H) = 6.50 Hz, 1H,
CH(CH3)2), 3.09 (sept, J(H-H) = 6.50 Hz, 1H, CH(CH3)2),
1.57 (s, 3H, CH3), 1.53 (s, 3H, CH3), 1.42 (d, 3J(H-H) = 6.50
Synthesis of [{HC(CMeNAr)2}SnC(CO2Et)CHCO2Et] (Ar =
2,6-iPr2C6H3) (7). A solution of diethyl acetylenedicarboxylate
(0.170 g, 1.00 mmol in 5 mL of toluene) was added drop by drop
by cannula to a solution of LSnH (0.540 g, 1.00 mmol in toluene
15 mL) at room temperature. After 6 h under constant stirring at
ambient temperature the yellow solution turned red. All vola-
tiles were removed from the solution in vacuo, and the remain-
ing residue was extracted with n-hexane (15 mL) and
concentrated to about 5 mL and stored in a -30 °C freezer.
Red crystals of 7 suitable for X-ray diffraction analysis are
formed after 1 day. Yield: 0.480 g (68%); mp 138 °C. 1H NMR
(500 MHz, C6D6): δ 7.05-7.16 (m, 6H, Ar-H), 6.93 (s, CH), 6.26
(s, CH), 4.87 (s, γ-CH), 4.85 (s, γ-CH), 4.22 (q, CH2), 4.03 (q,
CH2), 3.98 (q, CH2), 3.88 (m, CH(CH3)2), 3.84 (q, CH2), 3.28
3
Hz, 3H, CH(CH3)2), 1.37 (d, J(H-H) = 6.50 Hz, 3H, CH-
(CH3)2), 1.24 (d, 3J(H-H) = 6.50 Hz, 3H, CH(CH3)2), 1.21 (d,
3J(H-H) = 6.50 Hz, 3H, CH(CH3)2), 1.19-1.12 (m, 12H,
CH(CH3)2) ppm; 19F NMR (188.29 MHz): δ -77.39 (d, 3J-
(F-H) = 6.99 Hz, 3F, CF3) ppm; 119Sn{1H} NMR (186.46
MHz): δ -262 ppm; EI-MS (70 eV): m/z (%): 718 (100) [M]þ;
elemental analysis (%) anal. calcd for C35H45F3N2OSSn
(718.22): C, 58.59; H, 6.32; N, 3.90; S, 4.47. Found: C, 58.57;
H, 6.52; N, 3.84; S, 4.81.
Synthesis of [{HC(CMeNAr)2}SnOCH(C3H5)2] (Ar = 2,6-
iPr2C6H3) (4). A solution of dicyclopropylketone (0.110 g,

9548 Inorganic Chemistry, Vol. 48, No. 19, 2009
Jana et al.
(m, CH(CH3)2), 1.65 (s, CH3), 1.64 (s, CH3), 1.35 (t, CH3),
1.32-1.12 (m, CH(CH3)2), 1.06 (t, CH3), 0.95 (t, CH3), 0.87 (t,
CH3), 0.82 (t, CH3) ppm; 119Sn{1H} NMR (186.46 MHz): δ
-130.36, -211.20 ppm; EI-MS: m/z (%) 708 (100) [Mþ]. Anal.
calcd for C37H52N2O4Sn (708.29): C, 62.81; H, 7.41; N, 3.96.
Found: C, 60.63; H, 7.41; N, 3.64.
(m, 24H, CH(CH3)2), 1.25 (s, 9H, C(CH3)3) ppm. 119Sn{1H}
NMR (186.46 MHz): δ -123.27 and -205.75 ppm; EI-MS: m/z
(%) 707 (100) [M-tBu]þ. Anal. calcd for C41H60N2O4Sn
(764.36): C, 64.49; H, 7.92; N, 3.67. Found: C, 64.38; H, 8.08;
N, 3.59.
Crystallographic details for compounds 3, 4, 5, and 7. Suitable
crystals of 3, 4, 5, and 7 were mounted on a glass fiber, and data
was collected on an IPDS II Stoe image-plate diffractometer
Synthesis of [{HC(CMeNAr)2}SnC(CO2tBu)CHCO2tBu] (Ar =
2,6-iPr2C6H3) (8). A solution of ditertiarybutyl acetylenedicar-
boxylate (0.225 g, 1.00 mmol in 5 mL toluene) was added drop
by drop by cannula to a solution of LSnH (0.540 g, 1.00 mmol in
toluene 15 mL) at room temperature. After overnight constant
stirring at ambient temperature, all the volatiles were removed
from the solution in vacuo, and the remaining residue was
extracted with n-hexane (25 mL). Complete evaporation of the
filtrate resulted in a red power of the title compound 8. Yield:
0.490 g (64%); mp 179 °C. 1H NMR (500 MHz, C6D6): δ
7.06-7.15 (m, 6H, Ar-H), 6.93 (s, CH), 6.18 (s, CH), 4.92 (s,
γ-CH), 4.90 (s, γ-CH), 3.82 (m, 2H, CH(CH3)2), 3.36 (sept, 2H,
CH(CH3)2), 1.72 (s, 6H, CH3), 1.65 (s, 9H, C(CH3)3), 1.37-1.15
˚
(graphite monochromated Mo KR radiation, λ = 0.71073 A) at
133(2) K. The data was integrated with X-Area. The structures
were solved by Direct Methods (SHELXS-97)17 and refined by
full-matrix least-squares methods againstF2 (SHELXL-97).17 All
non-hydrogen atoms were refined with anisotropic displacement
parameters. Crystallographic data are presented in Table 1.
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft.
Supporting Information Available: X-ray data for 3, 4, 5, and 7
(CIF). This material is available free of charge via the Internet at
http://pubs.acs.org.
(17) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–122.