Ortho versus α-metalation of ethyl phenyl sulfide by n-butyllithium/N,N,N′,N′-tetramethylethylenediamine: Synthesis, reactivity, and crystal structures of (2-(ethylthio)phenyl)- and (1-(penylthio)ethyl)lithium

Article abstract of DOI:10.1021/om049886w

Metalation of ethyl phenyl sulfide by n-BuLi/tmeda (tmeda = N,N,N′,N′,-tetramethylethylenediamine) is strongly solvent dependent. In n-hexane and diethyl ether ortho lithiation took place, yielding (2-(ethylthio)phenyl)lithium, while in tetrahydrofuran (THF) α-lithiation occurred, yielding (1-(phenylthio)ethyl)lithium. From n-hexane solutions [{Li(C₆H₄SEt-2)-(tmeda)}₂] (4) was isolated as a white powder. Dissolution of 4 in THF resulted in isomerization, forming quantitatively the α-lithiated compound [Li(CHMeSPh)(tmeda)] (5). Compounds 4 and 5 reacted with n-Bu₃SnCl, yielding n-Bu ₃Sn(C₆H₄SEt-2) (1a) and n-Bu ₃SnCHMeSPh (2a), respectively. The identities of 4, 5, 1a, and 2a were confirmed by ¹H, ¹³C, and ¹¹⁹Sn (1a/2a) NMR measurements. Single-crystal X-ray diffraction analysis of 4 showed it to be dimeric, with a nonplanar four-membered ring composed of two lithium atoms and two ortho phenyl carbon atoms. The distorted-tetrahedral donor set of Li is completed by two nitrogen atoms (tmeda). Furthermore, from solutions of 4 in n-hexane crystals of [{Li(CHMeSPh)(tmeda)}₂(μ-tmeda)] (50 were obtained. X-ray structure analysis revealed the presence of centrosymmetric dimers. The primary donor set of Li is made up of one carbon atom and three nitrogen atoms, two of them from a chelating tmeda and the other from a bridging tmeda ligand.

Full text of DOI:10.1021/om049886w

3668
Organometallics 2004, 23, 3668-3673
Or th o ver su s r-Meta la tion of Eth yl P h en yl Su lfid e by
n -Bu tyllith iu m /N,N,N′,N′-Tetr a m eth yleth ylen ed ia m in e:
Syn th esis, Rea ctivity, a n d Cr ysta l Str u ctu r es of
(2-(Eth ylth io)p h en yl)- a n d (1-(P h en ylth io)eth yl)lith iu m
Matthias Linnert,† Clemens Bruhn,† Tobias Ru¨ffer,‡ Harry Schmidt,† and
Dirk Steinborn*,†
Institut fu¨r Anorganische Chemie der Martin-Luther-Universita¨t Halle-Wittenberg,
Kurt-Mothes-Strasse 2, D-06120 Halle/ Saale, Germany, and Institut fu¨r Chemie,
Technische Universita¨t Chemnitz, Strasse der Nationen 62, D-09107 Chemnitz, Germany
Received February 12, 2004
Metalation of ethyl phenyl sulfide by n-BuLi/tmeda (tmeda ) N,N,N′,N′-tetramethyleth-
ylenediamine) is strongly solvent dependent. In n-hexane and diethyl ether ortho lithiation
took place, yielding (2-(ethylthio)phenyl)lithium, while in tetrahydrofuran (THF) R-lithiation
occurred, yielding (1-(phenylthio)ethyl)lithium. From n-hexane solutions [{Li(C6H4SEt-2)-
(tmeda)}2] (4) was isolated as a white powder. Dissolution of 4 in THF resulted in
isomerization, forming quantitatively the R-lithiated compound [Li(CHMeSPh)(tmeda)] (5).
Compounds 4 and 5 reacted with n-Bu3SnCl, yielding n-Bu3Sn(C6H4SEt-2) (1a ) and n-Bu3-
1
SnCHMeSPh (2a ), respectively. The identities of 4, 5, 1a , and 2a were confirmed by H,
13C, and 119Sn (1a /2a ) NMR measurements. Single-crystal X-ray diffraction analysis of 4
showed it to be dimeric, with a nonplanar four-membered ring composed of two lithium
atoms and two ortho phenyl carbon atoms. The distorted-tetrahedral donor set of Li is
completed by two nitrogen atoms (tmeda). Furthermore, from solutions of 4 in n-hexane
crystals of [{Li(CHMeSPh)(tmeda)}2(µ-tmeda)] (5′) were obtained. X-ray structure analysis
revealed the presence of centrosymmetric dimers. The primary donor set of Li is made up of
one carbon atom and three nitrogen atoms, two of them from a chelating tmeda and the
other from a bridging tmeda ligand.
In tr od u ction
phenyl sulfides that lithiation of methyl phenyl sulfide
by n-BuLi in diethyl ether afforded LiCH2SPh, whereas
such reactions of phenyl sulfides containing higher alkyl
groups resulted in ortho lithiation.5 Such (2-(alkylthio)-
phenyl)lithium compounds proved to be versatile re-
agents in organic synthesis.6 Furthermore, better se-
lectivities in ortho lithiation have been achieved while
using n-BuLi/tmeda instead of n-BuLi.6,7 Benzyl phenyl
sulfide was found to react with n-BuLi/tmeda in hexane
to give the ortho-metalated product,6 whereas with
n-BuLi in THF/hexane R-metalation of the benzyl group
occurred.8 We here report reactions of ethyl phenyl
sulfide with n-BuLi/tmeda, which were investigated in
order to determine what factors influence ortho versus
R-lithiation.
R-Functionalized alkyllithium compounds of the type
LiCHRYR′n (R ) alkyl, H) with Lewis basic heteroatoms
Y (YR′n ) NR′2, PR′2, OR′, SR′, F, Cl, ...; R′ ) alkyl, aryl,
H) cover a wide range of stabilities, structures, and
reactivities.1 This can be understood in terms of an
electronic and/or steric influence of the Lewis basic
YR′n group upon the neighboring Li-C bond or directly
upon the Li atom. Sulfur-functionalized methyl com-
pounds of the type LiCH2SR′ have been well studied.2
Thus, only recently has a pronounced relationship
between the mononuclear structure of [Li(CH2SPh)-
(pmdta)] (pmdta ) N,N,N′,N′′,N′′-pentamethyldiethyl-
enetriamine) and its carbenoid reactivity been shown.3
Less investigated are analogous R-sulfur-functionalized
alkyllithium compounds of the type LiCHRSPh (R )
alkyl). This may be due to competitive ortho and
R-metalation.4 As early as 1940 Gilman showed for alkyl
Resu lts a n d Discu ssion
The reaction of ethyl phenyl sulfide with an equimolar
amount of n-BuLi/tmeda followed by addition of an
† Martin-Luther-Universita¨t Halle-Wittenberg.
‡ Technische Universita¨t Chemnitz.
(1) (a) Peterson, D. J . Organomet. Chem. Rev. A 1972, 7, 295-358.
(b) Krief, A. Tetrahedron 1980, 36, 2531-2640.
(2) Boche, G.; Lohrenz, J . C. W.; Cioslowski, J .; Koch, W. In
Supplement S: The Chemistry of Sulphur-containing Functional
Groups; Patai, S., Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1993;
pp 339-362.
(3) Ru¨ffer, T.; Bruhn, C.; Maulitz, A. H.; Stro¨hl, D.; Steinborn, D.
Organometallics 2000, 19, 2829-2831.
(4) Wheatley, A. E. H. Eur. J . Inorg. Chem. 2003, 3291-3303.
(5) (a) Gilman, H.; Webb, F. J . J . Am. Chem. Soc. 1940, 62, 987-
988. (b) Gilman, H.; Webb, F. J . J . Am. Chem. Soc. 1949, 71, 4062-
4066.
(6) Horner, L.; Lawson, A. J .; Simons, G. Phosphorus, Sulfur Relat.
Elem. 1982, 12, 353-356.
(7) Shirley, D. A.; Reeves, B. J . J . Organomet. Chem. 1969, 16, 1-6.
(8) (a) Zarges, W.; Marsch, M.; Harms, K.; Koch, W.; Frenking, G.;
Boche, G. Chem. Ber. 1991, 124, 543-549. (b) Schade, S.; Boche, G. J .
Organomet. Chem. 1998, 550, 359-379. (c) Schade, S.; Boche, G. J .
Organomet. Chem. 1998, 550, 381-395.
10.1021/om049886w CCC: $27.50 © 2004 American Chemical Society
Publication on Web 06/17/2004

(2-(Ethylthio)phenyl)- and (1-(Phenylthio)phenyl)lithium
Organometallics, Vol. 23, No. 15, 2004 3669
Sch em e 1
several weeks. Solutions of 4 in n-hexane were not
stable at room temperature, as indicated by a color
change from yellowish via orange (after 1-2 h) and then
to brown within several days. At -78 °C addition of a
solution of n-Bu3SnCl in n-hexane to a solution of [{Li-
(C6H4SEt-2)(tmeda)}2] (4) in n-hexane resulted in for-
mation of n-Bu3Sn(C6H4SEt-2) (1a ), which was isolated
in 49% yield as a colorless air-stable liquid: bp 135-
142 °C at 0.02 Torr (Scheme 2).
Ta ble 1. Meta la tion of RCH2SP h (R ) Me, H) by
n -Bu Li/tm ed a Accor d in g to Sch em e 1a
The identities of 4 and 1a were unambiguously proved
by NMR spectroscopy, and that of 4 was also proved by
a single-crystal X-ray diffraction analysis. 13C NMR
spectra of 4 in perdeuterated n-hexane and benzene
show six singlet resonances for aromatic C atoms,
proving the presence of an unsymmetrically disubsti-
tuted benzene derivative. The two ipso C atoms were
found to be strongly shifted to low field at 151.9/152.4
ppm (i-CSEt, C6D14/C6D6) and 185.7/185.5 ppm (i-CLi,
C6D14/C6D6). In comparison with PhLi, the resonance
of the ipso-C-Li atom is shifted to low field by about
14 ppm.13 The presence of a nonlithiated R-methylene
R ) Me
product composition, mol %
entry
solvent
n-hexane
n-hexane
time, h
1a
2a
3
1
2
3
4
24
1-2
70-75
10-20
70-80
5-10
1-2
8-12
45-50
0
75-85
5-10
0
Et2O/n-hexane (4/1) 2b
THF/n-hexane (4/1) 1-2b 2-5
R ) H
product composition, mol %
entry
solvent
time, h
1b
2b
3
1
group is clearly indicated in H NMR spectra, showing
5
6
n-hexane
n-hexane
24
0
90-95
45-50
0
triplet and quadruplet resonances for CH3CH2S groups
(CH3, 1.43/1.29 ppm; CH2, 2.89/2.79 ppm; C6D14/C6D6)
with the correct 3:2 intensity ratio. The identity of the
1-2
<5
45-50
The product composition is based on 119Sn spectroscopic
investigations. Addition of n-BuLi/tmeda at -78 °C.
a
b
1
ortho-metalated tin compound 1a was confirmed by H
and 13C NMR spectra. The magnitude of the coupling
constant in 1a (1J (Sn, CBu) ) 346.0 Hz) compared with
that in the parent compound n-Bu3SnPh (339.7 Hz)14
indicates that o-SEt substitution results in a diminished
electronic influence of the aryl ligand.15
equimolar amount of tri-n-butyltin chloride and analysis
of the organotin product via 119Sn NMR spectroscopy
showed a strong solvent influence on the course of the
reaction (Scheme 1, Table 1). In n-hexane and diethyl
ether ortho metalation was the predominant reaction;
R-metalation occurred only to a minor extent. Compari-
son of entries 2 and 3 (Table 1) shows that in diethyl
ether the reaction proceeded much faster. On the other
hand, in tetrahydrofuran predominantly R-metalation
occurred; the relatively low yield of about 50% resulted
from the limited stability of n-BuLi/tmeda in THF.9 For
comparison, methyl phenyl sulfide was metalated with
n-BuLi/tmeda in n-hexane under the same conditions.
After 24 h only R-metalated product was observed.
During shorter reaction times formation of smaller
amounts of ortho-metalated product was observed,
indicating that this is the kinetically favored process,
as already stated in refs 1a and 7. Comparison of entries
6 and 2 (Table 1) shows that metalation of methyl
phenyl sulfide proceeded faster than that of ethyl phenyl
sulfide. Metalation of MeSPh in more polar solvents
(ether, THF, tmeda) is known to proceed also by
R-metalation.5,10-12
Dissolving the ortho-lithiated compound 4 in THF-d8
resulted immediately in nearly quantitative isomeri-
zation to the R-metalated lithium compound [Li-
(CHMeSPh)(tmeda)] (5) (Scheme 2). As expected, reac-
tion of 5 with n-Bu3SnCl afforded n-Bu3SnCHMeSPh
(2a ), which was isolated as a colorless air-stable liquid
(bp 146-148 °C at 0.01 Torr) in 35% yield. The identities
of compounds 5 and 2a followed unambiguosly from the
1H, 13C, and 119Sn NMR spectra. The 13C NMR spectrum
of 5 shows four singlet resonances for aromatic carbon
atoms, as expected for a monosubsituted benzene de-
rivative. The resonance of the ipso carbon atom is
essentially the same as that of the corresponding C atom
in the ortho-metalated compound 4 (152.1 vs 152.4/151.9
ppm). R-Metalation results in a strong high-field shift
of the methlyene carbon atom (27.6 ppm in PhSEt16 vs
12.8 ppm in 5) and in a strong low-field shift of the
methyl carbon atom (14.3 ppm in PhSEt16 vs 22.4 ppm
1
in 5). Further proof for R-metalation came from the H
Cooling the reaction mixture of ethyl phenyl sulfide
with n-BuLi/tmeda in n-hexane to -78 °C resulted in
precipitation of the ortho-metalated product [{Li(C6H4-
SEt-2)(tmeda)}2] (4), which was isolated as a white
powder in 60% yield (Scheme 2). In air 4 immediately
went up in smoke. Even storage under argon at room
temperature for 1 week resulted in decomposition,
whereas at -40 °C no decomposition occurred over
NMR spectrum, showing for the SCHLiCH3 unit doublet
and quadruplet resonances in the correct 3:1 intensity
ratio. In comparison with the nonmetalated thioether,
the methine proton is shifted strongly to high field in 5
(2.94 versus 1.27 ppm). R-Metalation in the tin com-
pound 2a is clearly proved by the 1H and 13C NMR
1
spectra. The coupling constant J (Sn, CBu) ) 323.6 Hz
in 2a is smaller by 10.7 Hz than that in n-Bu3SnCH2-
SPh (334.3 Hz).17 Thus, as expected, substitution of H
(9) (a) Mallan, J . M.; Bebb, R. L. Chem. Rev. 1969, 69, 693-755. (b)
Scho¨llkopf, U. In Methoden der Organischen Chemie (Houben-Weyl);
Thieme-Verlag: Stuttgart, Germany, 1970; Vol. XIII/1, pp 3-25.
(10) Corey, E. J .; Seebach, D. J . Org. Chem. 1966, 31, 4097-4099.
(11) Amstutz, R.; Laube, T.; Schweizer, W. B.; Seebach, D.; Dunitz,
J . D. Helv. Chim. Acta 1984, 67, 224-236.
(13) Mann, B. E.; Taylor, B. F. 13C NMR Data for Organometallic
Compounds; Academic Press: London, 1981.
(14) Al-Allaf, T. A. K. J . Organomet. Chem. 1986, 306, 337-346.
(15) Steinborn, D. Angew. Chem., Int. Ed. Engl. 1992, 31, 401-421.
(16) Linnert, M. Diplomarbeit, Universita¨t Halle, 2002.
(17) Steinborn, D. Z. Chem. 1985, 25, 412-413.
(12) Seebach, D.; Gabriel, J .; Ha¨ssig, R. Helv. Chim. Acta 1984, 67,
1083-1099.

3670 Organometallics, Vol. 23, No. 15, 2004
Linnert et al.
Sch em e 2
by Me in the methylene group (SnCH2S versus SnCH-
(Me)S) results in an increased electronic influence of the
R-thioalkyl ligand.
distance is 2.568(6) Å. The structure of the Li2C2 ring
in 4 is very similar to that in the parent compound
[{LiPh(tmeda)}2] (Li‚‚‚Li ) 2.490(6) Å; Ci-Li‚‚‚Li′-Ci′
) -146.6°; interplanar angle Ph/Li2Ci 80.7°).18 It is
worth noting that in other tmeda adducts [{Li(tmeda)}2-
(µ-R)2] with four-membered Li2C2 rings the torsion
angles Ci-Li‚‚‚Li′-Ci′ were found to be between (149.3
and 180.0° (median 159.9°, n ) 8 observations).19 Thus,
the ring puckering in 4 (-147.1(2)°) is the largest one.
The phenyl rings include angles of 78.0(2) and 68.9-
(2)° with the Li1Li2C2 and Li1Li2C9 planes, respec-
tively. With respect to the central Li2C2 ring the two
ethylthio substituents are in syn positions. Thus, dimer
4 is a typical representative of an electron-deficient
bonding of the lithium atoms that are bridging between
sp2-hybridized carbon atoms. The carbon atoms which
are bonded to Li have small C-C-C angles (C1-C2-
C3/C10-C9-C14 ) 111.9(3)/111.3(3)°), while the neigh-
boring C atoms in the phenyl rings have large C-C-C
angles (124.0(3)-125.6(3)°). The same distortions were
found in structurally analogous aryllithium compounds
(Co-Ci-Co, median 112.5°, lower/upper quartile 112.2/
113.4°, n ) 108 observations; Cm-Co-Ci, median 124.5°,
lower/upper quartile 123.8/125.4°, n ) 216 observa-
tions), in particular in the parent compound [{LiPh-
(tmeda)}2] (Co-Ci-Co ) 111.8(3)° versus Cm-Co-Ci )
123.7(2)/125.5(3)°).18 Unexpectedly, in the solvate-free
polymeric LiPh all C-C-C angles were found to be
120.0(5)°.20
Crystals (colorless blocks) of compound 4 suitable for
single-crystal X-ray diffraction analysis were grown
from n-hexane solution at -40 °C. After several weeks
(-40 °C) a few single yellowish crystals of [{Li-
(CHMeSPh)(tmeda)}2(µ-tmeda)] (5′) precipitated from
these solutions. Compound 4 crystallized as isolated
dimeric molecules without unusual short inter-
actions (shortest contact between non-hydrogen atoms:
C20‚‚‚C21′ 3.401(5) Å). The molecular structure of the
dimer is shown in Figure 1, and selected bond lengths
and angles are given in Table 2. The central four-
membered Li2C2 ring is not planar; the dihedral angle
C2-Li1-Li2-C9 is -147.1(2)°. The Li-C bond lengths
are between 2.247(5) and 2.292(6) Å. The Li1‚‚‚Li2
The shortest Li‚‚‚S separations in 4 are Li1‚‚‚S1/
Li2‚‚‚S2 ) 3.457(5)/3.504(5) Å and do not indicate sulfur
coordination. These are much longer than those in [Li-
{CH(t-Bu)SPh}(µ-tmeda)1/2] (6) forming in the crystal
F igu r e 1. Solid-state structure of [{Li(C6H4SEt-2)(tme-
da)}2] (4; thermal ellipsoids at 25% probability). Hydrogen
atoms were omitted for clarity.
Ta ble 2. Selected In ter a tom ic Dista n ces (in Å) a n d
An gles (in d eg) in [{Li(C6H4SEt-2)(tm ed a )}2] (4)
Li1-C2
Li1-C9
Li2-C2
Li2-C9
Li1‚‚‚Li2
2.256(6)
2.278(5)
2.247(5)
2.292(6)
2.568(6)
S1-C1
S1-C29
S2-C10
S2-C15
Li-N
1.785(3)
1.795(4)
1.789(3)
1.812(4)
2.164(5)-2.285(5)
Li1-C2-Li2
Li1-C9-Li2
C2-Li1-C9
C2-Li2-C9
C1-C2-C3
C2-C1-C6
C2-C3-C4
69.5(2)
N1-Li1-N2
N3-Li2-N4
C1-S1-C29
C10-S2-C15
C10-C9-C14
C9-C14-C13
C9-C10-C11
83.2(2)
84.0(2)
68.4(2)
104.6(2)
104.4(2)
111.9(3)
124.0(3)
125.4(3)
one-dimensional infinite chains by bridging tmeda
105.3(2)
108.0(2)
111.3(3)
125.6(3)
125.4(3)
(18) (a) Thoennes, D.; Weiss, E. Chem. Ber. 1978, 111, 3157-3161.
(b) Cambridge Structural Database (CSD); Cambridge Crystallographic
Data Centre, University Chemical Laboratory, Cambridge, U.K. (ref-
code: PHENLI).

(2-(Ethylthio)phenyl)- and (1-(Phenylthio)phenyl)lithium
Organometallics, Vol. 23, No. 15, 2004 3671
criterion the Li-N bonds to the chelating and bridging
tmeda ligands are of the same length (2.183(2)/2.186-
(2) Å vs 2.191(2) Å). The (1-phenylthio)ethyl ligand is
η1 coordinated to Li with an Li-C1 distance of 2.184(2)
Å.
The anion stabilizing effect of sulfur is mainly due to
polarizability and negative hyperconjugation.2,22 In ac-
cordance with that, R-lithiation gives rise to a substan-
tial shortening of the S-Calkyl bond length (1.795(4)/
1.812(4) Å in 4 versus 1.766(1) Å in 5′). Although the
lone pair on C1 is nearly in an antiperiplanar position
to the σ*S-Ph orbital (Li-C1-S-C3 ) -163.94(8)°),
there is no lengthening of the S-CPh bond (1.785(3)/
1.789(3) Å in 4 vs 1.779(1) Å in 5′). Analogous values
were found in the solid-state structure of the monomeric
[Li(CHPhSPh)(THF)3] (S-Cbenzyl ) 1.76(1) Å, S-CPh
)
1.771(9) Å)8a as well as in the parent compound LiCH2-
SPh with tmeda, pmdta, and THF coligands (S-CH2 )
1.75(1)-1.780(7) Å, S-CPh ) 1.762(6)-1.81(2) Å).3,11,23
To summarize, the site of metalation of EtSPh by
n-BuLi/tmeda is solvent dependent: in nonpolar and
less polar solvents (n-hexane, Et2O) ortho lithiation
takes place, whereas in the more polar tetrahydrofuran
R-lithiation occurs, yielding [{Li(C6H4SEt-2)(tmeda)}2]
(4) and [Li(CHMeSPh)(tmeda)] (5), respectively. For the
first time, a solvent-induced isomerization of an ortho-
metalated lithium compound into an R-metalated one
(4 f 5) could be achieved. Recently, a slow THF-induced
isomerization (at higher temperatures) of ortho-lithiated
1-methoxynaphthalene into the peri-lithiated species
was observed.24 Furthermore, to synthesize 5 via isomer-
ization of 4 is superior to direct metalation of EtSPh by
n-BuLi/tmeda in THF, due to its limited stability in this
solvent. Investigations of the synthetic potential of this
new route to synthesize R-sulfur-substituted alkyl-
lithium compounds are in progress.
Figu r e 2. Solid-state structure of [{Li(CHMeSPh)(tmeda)}2-
(µ-tmeda)] (5′; thermal ellipsoids at 25% probability).
Hydrogen atoms of tmeda ligands were omitted for clarity.
From disordered carbon atoms C11/C12 only the major
occupied position (0.61) is shown.
Ta ble 3. Selected In ter a tom ic Dista n ces (in Å) a n d
An gles (in d eg) in
[{Li(CHMeSP h )(tm ed a )}2(µ-tm ed a )] (5′)
Li-C1
S-C1
S-C3
2.184(2)
1.766(1)
1.779(1)
Li-N1
Li-N2
Li-N3
2.191(2)
2.183(2)
2.186(2)
C1-Li-N1
C1-Li-N2
C1-Li-N3
C1-S-C3
108.55(9)
115.3(1)
118.3(1)
110.18(6)
N1-Li-N2
N1-Li-N3
N2-Li-N3
115.0(1)
112.18(9)
86.33(8)
ligands.21 In 6 the Li atom has a distorted-tetrahedral
coordination sphere consisting of two C atoms of phenyl
rings, one N atom, and one S atom (Li-S ) 2.712(5)
Å).
Compound 5′ crystallized as isolated dimeric mol-
ecules. There are no unusual intermolecular con-
tacts (shortest contact between non-hydrogen atoms:
C10‚‚‚C13′′ ) 3.635(3) Å). The dimer exhibits crystal-
lographically imposed Ci symmetry. Its structure is
shown in Figure 2. Selected bond lengths and angles
are depicted in Table 3.
The lithium atoms are four-coordinate with a (dis-
torted) tetrahedral coordination environment. The co-
ordination tetrahedron is defined by one carbon atom
and three nitrogen atoms belonging to a chelating and
a bridging tmeda ligand. The chelating tmeda ligands
form five-membered LiN2C2 rings exhibiting an ap-
proximate envelope conformation. Methylene carbon
atoms C11/C12 of chelating tmeda ligands are disor-
dered over two positions, corresponding to λδ and δλ
isomers of the five-membered rings. Within the 3σ
Exp er im en ta l Section
All reactions and manipulations were carried out under
purified argon using standard Schlenk techniques. Organotin
compounds were handled in air. n-Hexane, THF-d8, C6D6, and
n-C6D14 were dried with LiAlH4, and THF was distilled from
sodium benzophenone ketyl. NMR spectra were recorded on
Varian Gemini 200, Gemini 2000, and Unity 500 spectrometers
using the protio impurities and the 13C resonances of the
deuterated solvents as references for 1H and 13C NMR spec-
troscopy, respectively. δ(119Sn) is relative to external SnMe4
in C6D6.
Gen er a l P r oced u r e for Meta la tion of RCH2SP h (R )
Me, H). At 0 °C (using n-hexane) and -78 °C (using Et2O/
THF), respectively, to a stirred solution of n-BuLi in n-hexane
(10 mmol, 1.5 M) was added the solvent (20-30 mL) listed in
Table 1 and tmeda (10 mmol). Then, a solution of RCH2SPh
(10 mmol) in the solvent (5 mL) listed in Table 1 was added
within 15 min. The mixture was warmed to room temperature
and stirred for the time given in Table 1. A solution of n-Bu3-
SnCl (10 mmol) in the corresponding solvent (5 mL) was added
at -78 °C, and the mixture was stirred for 24 h at room
temperature. After the solvent was removed in vacuo, the
residue was examined by 119Sn NMR spectroscopy in CDCl3
(19) Cambridge Structural Database (CSD); Cambridge Crystal-
lographic Data Centre, University Chemical Laboratory, Cambridge,
U.K.
(20) Dinnebier, R. E.; Behrens, U.; Olbrich, F. J . Am. Chem. Soc.
1998, 120, 1430-1433.
(21) (a) Harder, S.; Brandsma, L.; Kanters, J . A.; Duisenberg, A. J .
M. Acta Crystallogr. 1987, C43, 1535-1537. (b) Bauer, W.; Klusener,
P. A. A.; Harder, S.; Kanters, J . A.; Duisenberg, A. J . M.; Brandsma,
L.; Schleyer, P. v. R. Organometallics 1988, 7, 552-555.
(22) (a) Reed, A. E.; Schleyer, P. v. R. J . Am. Chem. Soc. 1990, 112,
1434-1445. (b) Salzner, U.; Schleyer, P. v. R. J . Am. Chem. Soc. 1993,
115, 10231-10236.
(23) Becke, F.; Heinemann, F. W.; Steinborn, D. Organometallics
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3672 Organometallics, Vol. 23, No. 15, 2004
Linnert et al.
solution; proportionality between 119Sn integrals and Sn por-
tion was checked by measurements of pure tri-n-butyltin
compounds as reference substances.
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 4 a n d 5′
4
5′
[{Li(C6H4SEt-2)(tm ed a )}2] (4). At 0 °C to a stirred solution
of n-BuLi (50 mmol) in n-hexane (60 mL) was added dropwise
a solution of tmeda (5.8 g, 50 mmol) in n-hexane (10 mL). After
15 min a solution of PhSEt (6.9 g, 50 mmol) in n-hexane (10
mL) was added dropwise. Stirring for 4 h gave a clear orange
solution. Cooling to -78 °C resulted in precipitation of 4 as a
white powder, which was filtered at that temperature, washed
with n-hexane (2 × 10 mL), and dried in vacuo. Yield: 6.8 g
empirical formula
fw
T, K
cryst syst
space group
a, Å
b, Å
c, Å
C
28H50Li2N4S2
C34H66Li2N6S2
636.93
198(2)
monoclinic
P2/c
13.382(5)
8.615(4)
18.031(6)
520.72
223(2)
triclinic
P1h
8.536(2)
10.612(3)
18.575(5)
90.78(3)
101.44(3)
96.11(3)
1638.6(7)
2
1.055
0.183
568
2.20-25.00
11 754
5431 (Rint
0.0841)
325
1
3
R, deg
â, deg
γ, deg
V, Å3
Z
(60%). H NMR (400 MHz, C6D6): δ 1.29 (t, J H,H ) 7.47 Hz,
103.36(3)
3
3H, CH3CH2S), 1.94-1.97 (m, 16H, tmeda), 2.79 (q, J H,H
)
7.47 Hz, 2H, CH3CH2S), 6.98-7.13/8.07 (m/d, 3H/1H, C6H4).
2022.5(14)
2
1.046
0.160
700
1H NMR (400 MHz, n-C6D14): δ 1.43 (t, J H,H ) 7.47 Hz, 3H,
3
CH3CH2S), 2.14 (s, CH3N), 2.25 (s, CH2N), 2.89 (q, 3J H,H ) 7.47
F
calcd, g/cm3
Hz, 2H, CH3CH2S), 6.79/6.92/7.86 (m/t/d, 2H/1H/1H, C6H4). 13
C
µ(Mo KR), mm-1
F(000)
NMR (100 MHz, C6D6): δ 14.8 (s, CH3CH2S), 26.3 (s, CH3CH2S),
46.2 (s, CH3N), 57.5 (s, CH2N), 119.2/121.8/125.6/141.8 (s/s/s/
s, C6H4), 152.4 (s, i-CSEt), 185.5 (s, i-CLi). 13C NMR (100 MHz,
n-C6D14): δ 14.8 (s, CH3CH2S), 26.6 (s, CH3CH2S), 46.3 (s,
CH3N), 57.7 (s, CH2N), 119.2/121.7/125.3/141.4 (s/s/s/s, C6H4),
151.9 (s, i-CSEt), 185.7 (s, i-CLi). The powdery product contained
smaller amounts of additional tmeda.
scan range, deg
no. of rflns collected
no. of indep rflns
1.56-24.96
4798
)
3547 (Rint
0.0242)
219
)
no. of params refined
goodness of fit on F2
final R (I > 2σ(I))
0.956
1.048
R1 ) 0.0575
wR2 ) 0.1415
R1 ) 0.0954
wR2 ) 0.1639
0.477/-0.250
R1 ) 0.0398
wR2 ) 0.1023
R1 ) 0.0499
wR2 ) 0.1123
0.219/-0.222
n -Bu 3Sn (C6H4SEt-2) (1a ). To 4 (100 mmol) in n-hexane
(90 mL), cooled to -78 °C, was added dropwise a solution of
n-Bu3SnCl (30.0 g, 92 mmol) in n-hexane (20 mL). The reaction
mixture was warmed to room temperature over 6 h and stirred
overnight. A saturated aqueous solution of NH4Cl (200 mL)
was added at 0 °C. After phase separation, the aqueous phase
was extracted with diethyl ether (3 × 100 mL). The combined
organic phases were washed with water (3 × 50 mL) and dried
(Na2SO4). Solvents were removed in vacuo, and the residue
was fractionated (bp 135-142 °C at 0.02 Torr). Yield: 19.2 g
(49%). Anal. Calcd for C20H36SSn (427.28): C, 56.22; H, 8.49;
S, 7,50. Found: C, 56.54; H, 8,21; S, 7.12. 1H NMR (400 MHz,
CDCl3): δ 0.89-0.94/1.12-1.16/1.30-1.40/1.52-1.61(m/m/m/
R, all data
largest diff peak/hole, e/Å3
1
56.36; H, 8,18; S, 7.17. H NMR (200 MHz, CDCl3): δ 0.89-
1.06/1.11-1.18/1.27-1.41/1.45-1.62 (m/m/m/m, 30H, (C4H9)3-
Sn + CH3), 2.91-3.01 (m, 1H, CH(CH3)S), 7.10-7.17 (m, 1H,
p-CH), 7.23-7.36 (m, 4H, o-CH/m-CH). 13C NMR (100 MHz,
3
CDCl3): δ 13.7 (s, CH3 of Bu), 27.4 (s+d, J Sn,C ) 56.7 Hz,
2
3-CH2 of Bu), 29.2 (s+d, J Sn,C ) 20.7 Hz, 2-CH2 of Bu), 9.3
1
2
(s+d, J Sn,C ) 323.6 Hz, 1-CH2 of Bu), 19.7 (s+d, J Sn,C ) 10.0
Hz, CH(CH3)S), 21.5 (s+d, 1J Sn,C ) 250.2 Hz, CH(CH3)S), 125.3
(s, p-C), 128.5/128.6 (s/s, o-C and m-C), 138.2 (s, i-C). 119Sn
NMR (186 MHz, CDCl3): δ -7.9 (s).
3
m, ca. 30H, (C4H9)3Sn + CH3CH2S), 2.94 (q, J H,H ) 7.47 Hz,
2H, CH3CH2S), 7.13-7.18/7.24-7.32 (m/m, 1H/1H, H4 and H5
of Ph), 7.39 (m, 2H, H3 and H6 of Ph). 13C NMR (100 MHz,
Cr ysta llogr a p h ic Stu d ies. Single crystals of 4 (colorless
block, 0.60 × 0.60 × 0.21 mm) suitable for X-ray diffraction
measurements were obtained from the reaction mixture stored
for 1-2 days at -40 °C. From the same solutions very few
crystals of 5′ were obtained after several weeks. Intensity data
were collected on a STOE-STADI4 four-circle diffractometer
(5′) and STOE-IPDS diffractometer (4), respectively, with Mo
KR radiation (0.710 73 Å, graphite monochromator). A sum-
mary of crystallographic data, data collection parameters, and
refinement parameters is given in Table 4. The absorption
correction for 4 was applied numerically (Tmin/Tmax ) 0.90/0.96)
and for 5′ empirically via ψ-scans (Tmin/Tmax ) 0.68/0.85). The
structures were solved by direct methods using SHELXS-97
and refined with full-matrix least-squares routines against F2
using SHELXL-97.25 Non-hydrogen atoms were refined with
anisotropic and hydrogen atoms with isotropic displacement
parameters. H atoms were added to the model in their
calculated positions (riding model). In 5′ the ethylene bridge
of the tmeda ligand shows a typical disorder (λδ). Thus, carbon
atoms C11 and C12 are disordered over two positions with site
occupancies of 0.61 and 0.39. The corresponding disorder of
methyl carbon atoms C9/C10 and C13/C14 results in slightly
larger displacement ellipsoids.
3
CDCl3): δ 13.7 (s, CH3 of Bu), 27.5 (s+d, J Sn,C ) 61.4 Hz,
2
3-CH2 of Bu), 29.2 (s+d, J Sn,C ) 19.6 Hz, 2-CH2 of Bu), 11.0
(s+d, 1J Sn,C ) 346.0 Hz, 1-CH2 of Bu), 14.4 (s, CH3CH2S), 29.9
2
(s, CH3CH2S), 125.6 (s+d, J Sn,C ) 38.3 Hz, C6 of Ph), 128.7
4
3
(s+d, J Sn,C ) 8.8 Hz, C4 of Ph), 129.3/136.6 (s+d/s+d, J Sn,C
2
) 29.1/30.3 Hz, C3 and C5 of Ph), 144.5 (s+d, J Sn,C ) 22.7
Hz, C2 of Ph), 146.6 (s+d, J Sn,C ) 388.6 Hz, C1of Ph). 119Sn
1
NMR (186 MHz, CDCl3): δ -44.0 (s).
[Li(CHMeSP h )(tm eda)] (5) an d n -Bu 3Sn CHMeSP h (2a).
[Li(CHMeSP h )(tm ed a )] (5). (a) To a stirred solution of
n-BuLi (100 mmol) in n-hexane (60 mL)/THF (100 mL) was
added tmeda (11.6 g, 100 mmol) at -78 °C. After 15 min of
stirring PhSEt (13.8 g, 100 mmol) was added dropwise. The
reaction mixture was slowly warmed to room temperature and
stirred for 1-2 h.
1
(b) As shown by H and 13C NMR experiments, dissolution
of [{Li(C6H4SEt-2)(tmeda)}2] (4) (ca. 50 mg) in THF-d8 (ca. 1
1
mL) resulted in formation of 5. H NMR (400 MHz, THF-d8):
3
3
δ 1.27 (q, J H,H ) 6.23 Hz, 1H, LiCH(CH3)SPh), 1.53 (d, J H,H
) 6.23 Hz, 3H, LiCH(CH3)SPh), 2.18 (s, 12H, CH3N), 2.32 (s,
4H, CH2N), 6.69 (m, 1H, p-CH), 6.98/7.11 (m/m, 2H/2H, o-CH
and m-CH). 13C NMR (100 MHz, THF-d8): δ 12.8 (s, LiCH-
(CH3)SPh), 22.4 (s, LiCH(CH3)SPh), 46.2 (s, CH3N), 58.7 (s,
CH2N), 120.9 (s, p-C), 125.5 (s, m-C), 127.6 (s, o-C), 152.1 (s,
i-C).
Ack n ow led gm en t. Financial support by the Deut-
sche Forschungsgemeinschaft and the Fonds der Che-
mischen Industrie is gratefully acknowledged. We thank
Merck (Darmstadt, Germany) for gifts of chemicals.
n -Bu 3Sn CHMeSP h (2a ). From [Li(CHMeSPh)(tmeda)] (5),
prepared as described above, and n-Bu3SnCl (30.0 g, 92 mmol)
in THF (25 mL) at -10 °C tin compound 2a was obtained by
the same procedure as described for tin compound 1a (bp 146-
148 °C at 0.01 Torr). Yield: 13.6 g (35%). Anal. Calcd for
(25) Sheldrick, G. M. SHELXS-97 and SHELXL-97, Programs for
Crystal Structure Determination; University of Go¨ttingen, Go¨ttingen,
Germany, 1990, 1997.
C
20H36SSn (427.28): C, 56.22; H, 8.49; S, 7.50. Found: C,

(2-(Ethylthio)phenyl)- and (1-(Phenylthio)phenyl)lithium
Organometallics, Vol. 23, No. 15, 2004 3673
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic data are available as CIF files. This material is
available free of charge via the Internet at http://pubs.acs.org.
Crystallographic data (excluding structure factors) have been
also deposited at the Cambridge Crystallographic Data Center
as supplementary publication nos. CCDC-229877 (4) and
CCDC-229876 (5′). Copies of the data can be obtained free of
charge on application to the CCDC, 12 Union Road, Cam-
bridge, CB2, 1EZ, U.K. (fax, (internat.) +44(0)1223/336-033;
e-mail, deposit@ccdc.cam.ac.uk).
OM049886W