Chiral organotin hydrides containing intramolecular coordinating substituents

Article abstract of DOI:10.1016/S0022-328X(00)00315-6

A series of chiral non-racemic triorganotin halides and triorganotin hydrides containing one or two (1R,2S,5R)-menthyl (Men) substituents as well as the 8-dimethylaminonaphthyl (L) or 2-[(1S)-1-dimethylaminoethyl]phenyl (L*) substituents has been synthesised and characterised. Each of the compounds MenPhLSnBr (1) and MenPhLSnH (2) has a stereogenic tin centre and the compounds were isolated in diastereomeric ratios of 60:40 and 66:33, respectively. Compounds MenPhL*SnCl (3) and MenPhL*SnH (4) were synthesised with diastereomeric ratios of 73:27 and 64:36, respectively. Single crystal X-ray analysis of MenPhL*SnCl (3), Men₂L*SnCl (8), and MenPh₂LSn (10) reveals that each structure has a tendency towards penta-coordination at the tin centre as a result of intramolecular N→Sn interactions. AM1 calculations successfully predict the molecular geometries observed in the solid state as well as the diastereomeric ratios observed in solution.

Full text of DOI:10.1016/S0022-328X(00)00315-6

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 605 (2000) 209–220
Chiral organotin hydrides containing intramolecular coordinating
substituents
Dainis Dakternieks a,*, Kerri Dunn a, Carl H. Schiesser b, Edward R.T. Tiekink c
a Centre for Chiral and Molecular Technologies, Deakin Uni6ersity, Geelong, Victoria 3217, Australia
b School of Chemistry, Uni6ersity of Melbourne, Park6ille, Victoria 3052, Australia
c Department of Chemistry, Uni6ersity of Adelaide, Adelaide, South Australia 5005, Australia
Received 18 April 2000; accepted 18 May 2000
Abstract
A series of chiral non-racemic triorganotin halides and triorganotin hydrides containing one or two (1R,2S,5R)-menthyl (Men)
substituents as well as the 8-dimethylaminonaphthyl (L) or 2-[(1S)-1-dimethylaminoethyl]phenyl (L*) substituents has been
synthesised and characterised. Each of the compounds MenPhLSnBr (1) and MenPhLSnH (2) has a stereogenic tin centre and the
compounds were isolated in diastereomeric ratios of 60:40 and 66:33, respectively. Compounds MenPhL*SnCl (3) and
MenPhL*SnH (4) were synthesised with diastereomeric ratios of 73:27 and 64:36, respectively. Single crystal X-ray analysis of
MenPhL*SnCl (3), Men2L*SnCl (8), and MenPh2LSn (10) reveals that each structure has a tendency towards penta-coordination
at the tin centre as a result of intramolecular N“Sn interactions. AM1 calculations successfully predict the molecular geometries
observed in the solid state as well as the diastereomeric ratios observed in solution. © 2000 Elsevier Science S.A. All rights
reserved.
Keywords: Chiral; Organotin; Hydride
containing the intramolecular coordinating chiral 2-
[(1S)-1-dimethylaminoethylphenyl] ligand (L*) also dis-
1. Introduction
played some enantioselectivity in free radical reductions
[5]. The syntheses of several triorganostannanes con-
taining the chiral (1R,2S,5R)-menthyl (Men) have been
reported previously [6–11]. Amongst these was t-butyl-
8-(dimethylaminonaphthyl)-(1R,2S,5R)-menthyltin hy-
dride, which contains a stereogenic tin centre and was
Tri-n-butyltin hydride is an efficient, commonly
utilised reagent in free radical chemistry [1]. Reduction
reactions involving prochiral radicals must always re-
sult in racemic mixtures of the product owing to the
inability of Bu3SnH to differentiate between the two
faces of the prochiral carbon radical during delivery of
prepared in a 60:40 diastereomeric ratio [6]. Work in
the hydrogen atom from tin to carbon. Over recent
our group has demonstrated significant enhancement in
years there has been increased interest in the synthesis
enantioselectivities during asymmetric reductions in-
of chiral organotin hydrides as enantioselective free
volving chiral non-racemic stannanes by the incorpora-
radical reducing agents [2]. For example, Metzger et al.
tion of chiral and achiral Lewis acids [12]. As part of
[3] as well as Nanni and Curran [4] prepared organotin
hydrides containing the C2-symmetric binaphthyl moi-
ety. These stannanes induced some degree of enantiose-
lectivity during the free radical reduction of several
racemic alkyl halides. A series of organotin hydrides
our ongoing interest [10,13,14] in the development of
enantioselective free radical reducing agents, we now
focus on the synthesis of a series of chiral organotin
hydrides which contain the chiral (1R,2S,5R)-menthyl
substituent (Men) as well as potentially intramolecular
coordinating 8-(dimethylamino)naphthyl (L) (see
Scheme 1) and L* (see Scheme 2) ligands. The enan-
tioselectivity of organotin the hydrides in a cross-sec-
tion of radical reactions is currently being evaluated.
* Corresponding author. Fax: +61-352-272218.
E-mail address: dainis@deakin.edu.au (D. Dakternieks).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00315-6

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D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
Scheme 1.
Scheme 2.
2. Results and discussion
Reaction of 1 with lithium aluminium hydride
(LiAlH4) results in formation of MenPhLSnH (2)
(Scheme 1) in a diastereomeric ratio of 66:34, as evi-
denced by the 119Sn proton-coupled NMR spectrum
(C6D6) which exhibited two doublets; l −115.0,
2.1. Monomenthyltin deri6ati6es
The synthesis of the first target compound, namely
8 - (dimethylamino) - naphthyl - (1R,2S,5R) - menthyl-
phenyltin hydride (2) was achieved as follows. Reaction
of one molar equivalent of 8-(dimethylamino)-
naphthyllithium (LiL), as the etherate, with
MenPhSnBr2 (Scheme 1) in diethyl ether results in a
white solid, which has elemental analysis consistent
with the formula MenPhLSnBr (1). The 119Sn-NMR
spectrum (C6H6) of the isolated product contains two
signals at l −89.4 and −119.6 and were observed in
a 60:40 ratio which are assigned to the two possible
diastereomers of 1 (Fig. 1). The 13C-NMR spectra
(toluene-d8) of 1 at room temperature contains four
sharp singlets (l 47.12, 47.59, 49.98 and 50.62) corre-
sponding to the two non-equivalent methyl groups at
the nitrogen of the dimethylaminonaphthyl substituent
for each diastereomer. These signals most likely indi-
cate that the nitrogen is effectively coordinated to the
tin centre. This is supported by the crystal structure of
1
1J(119Sn–1H) 1955 Hz and −140.0, J(119Sn–1H) 1980
Hz.
1
The H-NMR spectra (C6D6) of 2 at room tempera-
ture contains four singlets (l 2.24, 2.28, 2.50, 2.54)
corresponding to two non-equivalent methyl sub-
stituents attached to the nitrogen in the L moiety for
each of the two isomers. As is the case for 1, the
nitrogen appears to be coordinated to the tin centre,
even though the tin centre in 2 might be expected to
have a lower Lewis acidity. Heating a toluene solution
of 2 at 100°C for 20 minutes caused no change in the
66:34 diastereomeric ratio as evidenced by 119Sn-NMR.
Attention was then directed to the preparation of
MenPhL*SnH (4) which was prepared as described.
Addition of L*Li to MenPhSnCl2 in diethyl ether af-
fords MenPhL*SnCl (3) in a 69% yield (Scheme 2). The
119Sn-NMR spectrum (CHCl3) of an analytically pure
sample of 3 shows two resonances at l −123.8 and
−146.4 in the ratio 73:27 corresponding to the two
diastereomers of 3. The 13C-NMR spectrum (CDCl3) of
3 at room temperature displays two separate, somewhat
broad, resonances for the nitrogen-bound methyl
groups of the L* substituent of each isomer (l 36.9
(W1/2 40 Hz) and 43.9 (W1/2 40 Hz) for the major
isomer, l 37.8 (W1/2 80 Hz) and 45.2 (W1/2 80 Hz) for
the minor isomer). The difference in chemical shifts, i.e.
approximately 7 ppm between the two methyl groups of
each isomer, suggest that the two methyl groups exist in
a
similar compound, 8-(dimethylamino)naphthyl-
(1R,2S,5R)-menthylmethyltin bromide (MenMeLSnBr)
,
[15] which has a NꢀSn bond distance of 2.55(1) A. The
13C-NMR spectrum of this product also exhibited sepa-
rate signals for each methyl group. Attempts to obtain
crystals of 1 suitable for X-ray study were not
successful.
Interestingly, there is no substantive change in the
13C-NMR spectra on heating solutions of 1 to 90°C.
Furthermore there is no change in the ratio of the two
119Sn resonances after a toluene solution of 1 had been
heated at 115°C for 24 h. The remarkably high configu-
rational stability of the two isomers of 1 can be largely
ascribed to the rigid aromatic ring system which ensures
that the nitrogen of the dimethylamino group is kept in
close proximity to the tin atom.
Attempts to separate the two isomers of 1 using
normal-phase chromatography, MPLC, HPLC and
crystallisation were not successful.
Fig. 1. Diagram representing the two diastereomers of compound 1.

D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
211
Fig. 2. Molecular structures and atomic numbering scheme for (A) molecule a, and (B) molecule c, of MenPhL*SnCl (3); the numbering scheme
for molecule b follows that of molecule a.
are collected in Table 1. The tin atom in each molecule
is bonded to three carbon atoms, a chlorine as well as
the amino-nitrogen atom. The Sn···N distances lie in
significantly different chemical environments. A smaller
difference of approximately 3 ppm is observed for the
two methyl groups of the L moiety in compound 1. On
heating a solution of 3 in toluene to 105°C the four
methyl 13C-NMR (toluene-d8) resonances coalesce into
two signals, indicating dissociation of the N“Sn coor-
dination. Heating the toluene solution of 3 at 105°C for
18 hours caused no change in the ratio of the two
119Sn-NMR signals. The 119Sn-NMR spectrum of a
solution of compound 3 in dichloromethane showed no
change in the diastereomeric ratio after two weeks a
20°C.
,
the range 2.58(2)–2.64(2) A. The overall molecular
structure for each molecule is consistent with a dis-
torted trigonal bipyramidal geometry in which the tin
,
atom lies 0.189(2) A above the C3 trigonal plane in the
direction of the chlorine atom; the comparable values
,
for molecules b and c are 0.173(2) and 0.237(2) A,
respectively. This is comparable with the compound of
(RSn)-[8-(dimethylaminonaphthyl]-(1R,2S,5R)-menthyl-
methyltin bromide which also had a distorted trigonal
bipyramidal coordination geometry at the tin centre
The X-ray analysis of 3 was carried out on a crystal
,
with a Sn···N distance of 2.55(1) A [15]. The most
obtained from the slow evaporation of
a
1:1
significant consequence of the differing stereochemistry
found for the tin atoms in molecules a and b and that
observed in molecule c is found in the distortion in the
C3 trigonal plane. Thus, there is a significant (approxi-
mately 10°) expansion and contraction of the
C(1)ꢀSnꢀC(7) and C(1)ꢀSnꢀC(17) angles, respectively,
in molecule c compared with molecules a and b.
dichloromethane–methanol solution. The unit cell
comprises three independent molecules with two
molecules, i.e. a and b, adopting an S configuration at
the stereogenic tin centre and the third molecule, c,
adopting a R configuration. Molecules a and c are
illustrated in Fig. 2 and selected interatomic parameters

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D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
Fig. 2. (Continued)
The use of LiAlH4 as a reducing agent appears to
destroy compound 3. The 119Sn-NMR spectrum of the
reaction mixture indicated the absence of any 119Sn
products. However, reaction of sodium borohydride
Table 1
Selected interatomic (A, °) parameters for MenPhL*SnCl (3)
,
(NaBH4) with
3 in ethanol solution affords a
Molecule a
Molecule b
Molecule c
diastereomeric mixture of MenPhL*SnH (4) in 95%
yield (Scheme 2). The 119Sn proton-coupled NMR spec-
trum of 4 displays two doublet resonances (l −136.7,
SnꢀCl
SnꢀN
SnꢀC(1)
SnꢀC(7)
SnꢀC(17)
2.496(5)
2.58(2)
2.16(2)
2.13(2)
2.16(2)
2.486(6)
2.64(2)
2.16(2)
2.14(2)
2.15(2)
2.464(7)
2.60(2)
2.12(2)
2.14(2)
2.17(2)
1J(1H–119Sn) 1920 Hz and −166.8, J(1H–119Sn) 1904
1
Hz) in a 64: 36 ratio. The 13C- and H-NMR (C6D6)
1
spectra of 4 at room temperature displays a single
signal (l 40.26, 40.82 and 1.86, 1.92, respectively) for
the two methyl groups of the dimethylamino-
ethylphenyl substituent for each diastereomer of 4 indi-
cating no N“Sn coordination. On cooling the 13C-
NMR signals corresponding to the methyl groups
coalesce at approximately −50°C.
In order to provide further insight into the structures
and energies of the two tin-epimeric diastereomers of
MenPhLSnBr (1) and MenPhL*SnCl (3), the ge-
ClꢀSnꢀN
166.3(4)
92.1(5)
95.6(5)
97.4(5)
87.2(7)
73.0(6)
94.8(6)
119.3(7)
119.9(7)
118.5(8)
167.6(4)
92.4(5)
94.6(5)
96.8(5)
90.8(6)
73.3(6)
91.9(6)
116.0(8)
120.7(7)
121.4(8)
168.8(4)
96.0(7)
97.8(6)
95.5(5)
87.8(8)
71.0(7)
89.7(7)
107.1(9)
131.7(7)
117.5(7)
ClꢀSnꢀC(1)
ClꢀSnꢀC(7)
ClꢀSnꢀC(17)
NꢀSnꢀC(1)
NꢀSnꢀC(7)
NꢀSnꢀC(17)
C(1)ꢀSnꢀC(7)
C(1)ꢀSnꢀC(17)
C(7)ꢀSnꢀC(17)

D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
213
Fig. 3. AM1 calculated geometries of both diastereomers of compounds 1 and 3.
ometries of 1 and 3 were optimised using the AM1
semiempirical molecular modelling technique [16]. The
calculated lowest-energy structures are displayed in Fig.
3 together with the AM1 calculated relative energy of
each isomer; full details are available as Supporting
Information. Inspection of Fig. 3 reveals that the calcu-
lated structures of 3 bear a striking resemblance to the
X-ray structures displayed in Fig. 2. The tin atom in
each molecule is shown to be coordinated to the amino-
nitrogen atom, with calculated NꢀSn separations in
of the S isomer of 1 is remarkably similar to the
analogous X-ray structure of MenMeLSnBr reported
by Schumann et al. [15]. Both structures are, once
again, calculated to have significant NꢀSn bonding,
,
with separations of 2.99 and 3.04 A for (SSn)-1 and
(RSn)-1, respectively, and calculated associated bicentric
energies of −0.86 and −0.74 eV. Clearly, the NꢀSn
interactions in structures 1 are predicted to be mar-
ginally weaker than the corresponding interactions in 3.
To our delight, AM1 calculations predict that the S
isomer of MenPhLSnBr (1) is more stable than (RSn)-1
by only 0.8 kJ mol−1. Using the same argument pre-
sented above, this difference translates into a 60:40
ratio of isomers at 25°C, once again in excellent agree-
ment with the available experimental data; the 119Sn-
,
(SSn)-3 and (RSn)-3 of 2.86 and 2.71 A, respectively, in
good agreement with the X-ray determined values, such
,
as 2.55(1) A for MenMeLSnBr [15]. In addition, energy
partitioning [17–19] within the AM1 framework reveals
an (attractive) NꢀSn bicentric energy of −1.43 and
−1.96 eV for the S and R isomers, respectively. More
importantly, these calculations predict that (SSn)-3 lies
1.8 kJ mol−1 below (RSn)-3 in energy. Assuming that
this enthalpy difference is reflected in the difference in
free energies, this value of 1.8 kJ mol−1 translates into
a 2:1 ratio of isomers at 25°C in favour of (SSn)-3, a
result which is in excellent agreement with the experi-
mental data (vide supra).
NMR spectrum of
1
reveals two signals in
approximately 60:40 ratio (vide supra). On the basis of
the exceptional agreement between calculated and ex-
perimental data, we tentatively assign the major
diastereomer of 1 to be (SSn)-MenPhLSnBr.
2.2. Dimenthyltin deri6ati6es
These calculated data provide confidence in our abil-
ity to predict the structures and energies of the isomers
of MenPhLSnBr (1) for which no X-ray data are avail-
able. Fig. 3 reveals that the AM1 calculated geometry
The addition of one molar equivalent of LiL to
Men2SnCl2 (5) (prepared by treatment of HgCl2 with
Men2Ph2Sn in acetone) in diethyl ether affords
Men2LSnCl (6) (Scheme 3); 119Sn-NMR (CDCl3): l

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D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
−49.6. The 13C- and H-NMR (CDCl3) spectra of 6
contain two resonances (l 48.51, 50.12 and 2.76, 2.88,
respectively) corresponding to the diastereotopic methyl
groups on the nitrogen of the L substituent.
1H-NMR spectra (C6D6) of 9 at room temperature each
displayed a single resonance (l 41.32 and 2.05, respec-
tively) for the nitrogen-bound methyl groups of the
dimethylaminoethylphenyl ligand indicating their
equivalence and suggests that the N“Sn association/
dissociation of 9 is fast on the NMR timescale. There
are no substantial changes in the 13C-NMR spectra at
temperatures down to −70°C.
1
Reduction of 6 with LiAlH4 in diethyl ether gave the
hydride, Men2LSnH (7) (Scheme 3). The 119Sn-NMR
(C6D6) spectrum of 7 displays a doublet l −104.6
1
(1J(119Sn–1H) 1729 Hz). The 13C- and H-NMR (tolu-
ene-d8) spectra at 20 and 100°C of 7 contain two
separate peaks (l 46.33, 47.79 and 2.44, 2.48, respec-
tively) associated with the two methyl groups of the L
substituent, again indicating coordination of the nitro-
gen to the tin centre.
Some tetraorganotin compounds were synthesised to
compare the degree of intramolecular coordination with
the corresponding organotin halides and organotin hy-
drides. The reaction of an excess of LiL with
MenPh2SnF in diethyl ether afforded MenPh2LSn (10)
as a white solid in a 32% yield (119Sn-NMR (C6H6): l
−107.1). The 13C- and 1H-NMR spectra indicated
N“Sn coordination in solution and this was confirmed
by a crystal structure of 10 (as a 1:2 chloroform sol-
vate). Two molecules of 10 comprise the crystallo-
graphic asymmetric unit, however, there are only minor
conformational differences between them as illustrated
in Fig. 5; selected interatomic parameters are collected
in Table 3. The tin atom in each molecule is bound by
four carbon atoms and exists in a distorted tetrahedral
geometry. The range of tetrahedral angles subtended at
the Sn(1) atom of 102.5(3)–119.4(3)° (101.7(3)–
119.2(3)° for the Sn(2) atom) suggests relatively little
distortion from the ideal geometry. The maximum devi-
ation in each case may be traced to the presence of
close intramolecular N(1)“Sn(1) and N(2)“Sn(2) in-
The reaction of L*Li with 5 afforded Men2L*SnCl
(8) quantitatively as a white crystalline solid (Scheme
3). The 13C- and 1H-NMR (CDCl3) spectra of 8 at
room temperature contained a single broad resonance
(l 40.13 and 2.25, respectively) for the two methyl
substituents of the L* moiety. Coalescence of the 13C-
NMR resonance was observed at 0°C, and two separate
signals (l 36.7 and 42.8) are visible at −55°C. We
attribute this to a dynamic N“Sn dissociation/associa-
tion process in solution, which is fast compared with
the NMR time scale at room temperature. Coalescence
occurs at a lower temperature compared with 3, consis-
tent with decreased Lewis acidity of the tin centre in 8.
The structure of
8
was determined by X-ray
crystallography.
The structure of 8 is shown in Fig. 4 and selected
interatomic parameters are listed in Table 2. The imme-
diate geometry about the tin atom is defined by three
carbon atoms and a chlorine atom. The close approach
,
teractions of 2.882(7) and 2.899(7) A, respectively. The
overall molecular geometry, including the magnitude of
the distortions, seen in 10 matches those found for the
two independent molecules of the triphenyltin analogue
[20]. The increased magnitude of the intramolecular
Sn···N(1) interaction in 8 compared with that found in
10 may be related, in the first instance, to the enhanced
Lewis acidity of the tin centre in 8 having a C3Cl donor
set as opposed to a C4 donor set as in 10.
,
of the amino-nitrogen atom, i.e. Sn···N is 2.640(3) A,
has a significant structural impact, however, so that the
molecular geometry may be described as being interme-
diate between tetrahedral and trigonal bipyramidal. In
,
the latter description the tin atom lies 0.2293(2) A
above the trigonal C3 plane in the direction of the
chloride atom; the ClꢀSn···N(1) axial angle is
169.11(7)°.
Addition of an excess of LiL to Men2PhSnI in te-
tramethylethylenediamine
(TMEDA)
afforded
Reduction of 8 with LiAlH4 afforded Men2L*SnH
(9) in a 78% yield (Scheme 3). The 119Sn proton-coupled
NMR spectrum (C6D6) of 9 displayed a doublet l
−141.3 ppm (1J(119Sn–1H) 1688 Hz). The 13C- and
Men2PhLSn (11) in a 33% yield (119Sn-NMR (CHCl3):
l −99.1). The use of TMEDA as a solvent system was
required, there being no reaction in diethyl ether, nor in
diethyl ether containing only one molar equivalent of
Scheme 3.

D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
215
Fig. 4. Molecular structure and atomic numbering scheme for Men2L*SnCl (8).
1
TMEDA. The 13C- and H-NMR (CDCl3) spectra for
trospray mass spectra were obtained on a Bruker
BioApex 47e FT mass spectrometer. All solvents and
reagents used were of analytical reagent grade. Reac-
tions were generally carried out in an atmosphere of
dry nitrogen or dry argon. LiL as the etherate [21],
LiL* [22], MenPh2SnF, MenPhSnBr2 [10], Men2PhSnI
11 displays two signals (l 40.48, 50.98 and 2.47, 2.76,
respectively) for the two diastereomeric methyl groups
again indicating association of the nitrogen to the tin
centre.
3. Experimental
Table 2
3.1. General methods
,
Selected interatomic (A, °) parameters for Men2L*SnCl (8)
SnꢀCl
SnꢀC(11)
SnꢀN(1)
2.474(1)
2.196(4)
2.640(3)
SnꢀC(1)
SnꢀC(21)
2.195(4)
2.155(4)
NMR spectra were obtained using a JEOL-GX 270
FT NMR spectrometer (119Sn inverse-gated or 119Sn
proton-coupled and 19F), referenced to Me4Sn and
CFCl3, respectively, and a Varian 300 MHz Unity Plus
NMR spectrometer (1H and 13C), referenced to TMS.
Uncorrected melting points were determined on a
Kofler hot stage. Microanalyses were performed at
Dortmund University (Germany). High-resolution elec-
ClꢀSnꢀC(1)
92.56(9)
98.4(1)
132.2(1)
87.0(1)
ClꢀSnꢀC(11)
ClꢀSnꢀN(1)
C(1)ꢀSnꢀC(21)
C(11)ꢀSnꢀC(21)
C(21)ꢀSnꢀN(1)
97.6(1)
169.11(7)
112.2(1)
112.2(1)
71.8(1)
ClꢀSnꢀC(21)
C(1)ꢀSnꢀC(11)
C(1)ꢀSnꢀN(1)
C(11)ꢀSnꢀN(1)
90.7(1)

216
D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
Fig. 5. Molecular structures and atomic numbering scheme for the two independent molecules of MenPh2LSn (10).
[10] and MenPhSnCl2 [10] were prepared as previously
reported.
25.40, 31.71, 34.05, 34.50, 40.31, 43.36 (J(13C–119Sn)
567 Hz), 43.74, 47.59, 49.98, 115.67, 125.14, 126.31,
126.63, 127.70 (2C), 128.03, 128.61, 133.06, 133.43,
134.97 (J(13C–119Sn) 616 Hz), 134.92 (2C), 136.57,
144.97 (J(13C–119Sn) 636 Hz), 148.85. 119Sn-NMR
(CDCl3): l (Rint, %) −89.4 (60), −119.6 (40). Anal.
Calc for C28H36BrNSn: C, 57.5; H, 6.2; N, 2.4. Found:
C, 58.2; H, 6.3; N, 2.9%.
3.2. Syntheses
3.2.1. MenPhLSnBr (1)
A suspension of LiL·Et2O (1.22 g, 4.86 mmol) in
diethyl ether (100 ml) was added to a stirred solution of
MenPhSnBr2 (1.5 g, 3.03 mmol) in diethyl ether (20
ml). The reaction mixture was stirred at room tempera-
ture (r.t.) for 86 h and the solvent was removed in
vacuo. The residue was purified by column chromatog-
raphy (silica gel 60, 70–230 mesh) using a 70:30 hex-
ane–dichloromethane solvent system. Removal of the
solvent in vacuo yielded a red crystalline solid (1.2 g,
68%); m.p. 49–52°C. 13C-NMR (CDCl3): major
diastereomer: l 15.73, 21.08, 21.56, 25.40, 32.86, 34.01,
34.27, 38.60, 41.84 (J(13C–119Sn) 556 Hz), 43.59, 47.12,
50.62, 115.81, 124.96, 126.31, 126.47, 127.80 (2C),
128.21, 128.71, 132.28 (J(13C–119Sn) 553 Hz), 133.43,
133.55, 134.32 (2C), 137.96, 145.70 (J(13C–119Sn) 612
Hz), 149.09; minor diastereomer: l 14.53, 20.85, 22.01,
3.2.2. MenPhLSnH (2)
A solution of 1 (0.26 g, 0.45 mmol) in diethyl ether
(10 ml) was added to a suspension of LiAlH4 (0.18 g,
4.7 mmol) in diethyl ether (3 ml), and stirred at r.t. for
18 h. Water (2 ml) was carefully added, followed by a
20% solution of potassium/sodium-(+)-tartrate (2 ml).
The residue was extracted with diethyl ether (2×5 ml)
and the combined organic extracts were dried (Na2SO4)
and the solvent removed in vacuo to yield 2 as a yellow
1
oil (0.15 g, 66%). H-NMR (C6D6): l 0.07–2.19 (38H,
m, both isomers), 2.24 (3H, s, minor isomer), 2.28 (3H,
s, major isomer), 2.50 (3H, s, minor isomer), 2.54 (3H,
s, major isomer), 6.77 (1H, s, minor isomer), 6.91 (1H,

D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
217
Fig. 5. (Continued)
s, major isomer), 6.82–8.34 (22H, m, both isomers).
119Sn-NMR (C6D6): l (Rint, %) −140.0 (66) (d,
J(119Sn–1H) 1980 Hz), −115.0 (33%) (d, J(119Sn–1H)
1955 Hz). HRMS (ESI): m/z Calc. for C28H37SnN
[M−H]+: 506.1861. Found: 506.1868.
22.23, 25.97, 33.80, 34.77, 34.95, 36.90 (broad, W1/2 40
Hz), 39.78, 43.54 (J(13C–119Sn) 600 Hz), 43.88, 43.90
(broad, W1/2 40 Hz), 61.31, 125.12, 127.11, 128.15 (2C),
128.64, 129.06, 135.63 (2C), 138.21, 139.78, 144.07
(J(13C–119Sn) 607 Hz), 147.92; minor diastereomer: l
10.58, 16.03, 21.50, 22.45, 26.27, 32.36, 34.56, 35.10,
37.8 (broad, half width 80 Hz), 40.41, 41.73 (J(13C–
119Sn) 576 Hz), 43.77, 45.2 (broad, half width 80 Hz),
63.54, 125.36, 127.38, 128.02 (2C), 128.27, 129.09,
135.79 (2C), 136.96, 141.67, 144.91 (J(13C–119Sn) 653
3.2.3. MenPhL*SnCl (3)
A solution of LiL* (1.53 g, 9.79 mmol) in diethyl
ether (20 ml) was added to a solution of MenPhSnCl2
(3.31 g, 8.16 mmol) in diethyl ether (40 ml) at 0°C, and
the resultant solution stirred at r.t. for 18 h. Saturated
ammonium chloride (2 ml), then water (20 ml) were
added. The mixture was extracted with dichloro-
methane (2×40 ml), the combined organic extracts
were dried (Na2SO4) and the solvent removed in vacuo
to afford 3 as an orange oil in quantitative yield which
was triturated from methanol afforded a white crys-
Table 3
,
Selected interatomic (A, °) parameters for MenPh2LSn (10)
Sn(1)ꢀC(1)
Sn(1)ꢀC(7)
Sn(1)ꢀC(13)
Sn(1)ꢀC(23)
Sn(1)ꢀN(1)
2.162(8)
2.156(8)
2.176(8)
2.160(9)
2.882(7)
Sn(2)ꢀC(35)
Sn(2)ꢀC(41)
Sn(2)ꢀC(47)
Sn(2)ꢀC(57)
Sn(1)ꢀN(1)
2.179(9)
2.129(8)
2.148(8)
2.147(9)
2.899(7)
1
talline solid (2.18 g, 52%); m.p. 144–145°C. H-NMR
(CDCl3): l 0.58–2.46 (50H, m, both isomers), 1.24 (3H,
d, minor isomer), 1.28 (3H, d, minor isomer), 3.49 (1H,
q, major isomer), 3.91 (1H, q, minor isomer), 7.21–7.65
(16H, m, both isomers), 8.34–8.36 (1H, m, major iso-
mer), 8.45–8.48 (1H, m, minor isomer). 13C-NMR
(CDCl3): major diastereomer: l 8.53, 16.19, 21.80,
C(1)ꢀSn(1)ꢀC(7)
C(1)ꢀSn(1)ꢀC(13)
C(1)ꢀSn(1)ꢀC(23)
C(7)ꢀSn(1)ꢀC(13)
C(7)ꢀSn(1)ꢀC(23)
102.5(3)
103.9(3)
103.3(3)
119.4(3)
112.8(3)
C(35)ꢀSn(2)ꢀC(41)
C(35)ꢀSn(2)ꢀC(47)
C(35)ꢀSn(2)ꢀC(57)
C(41)ꢀSn(2)ꢀC(47)
C(41)ꢀSn(2)ꢀC(57)
C(47)ꢀSn(2)ꢀC(57)
101.7(3)
104.2(3)
104.1(3)
119.2(3)
113.9(3)
111.6(3)
C(13)ꢀSn(1)ꢀC(23) 112.6(3)

218
D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
Hz), 146.38. 119Sn-NMR (CHCl3): major diastereomer:
l (Rint, %) −123.8 (73); minor diastereomer: l (Rint, %)
−146.4 (27). Anal. Calc. for C26H38ClNSn: C, 60.2; H,
7.4; N, 2.7. Found: C, 60.2; H, 7.4; N, 2.8%.
reaction mixture was stirred at r.t. for 18 h. Saturated
ammonium chloride (2 ml) was added and the resultant
mixture extracted with diethyl ether (3×20 ml). The
combined extracts were dried (MgSO4) and the solvent
removed in vacuo. The residue was purified by column
chromatography (silica gel 60, 70–230 mesh) using
gradient elution with a 70:30:1 solution of hexane–
dichloromethane–triethylamine followed by acetone
and then methanol. Removal of solvent in vacuo
yielded the crude product as a brown oil (2.07 g, 70%).
The product was dissolved in dichloromethane (20 ml),
washed with 1 M HCl (20 ml), dried (Na2SO4) and the
solvent was removed in vacuo to obtain 6 as a maroon
3.2.4. MenPhL*SnH (4)
A solution of NaBH4 (0.27 g, 7.14 mmol) in ethanol
(30 ml) was added to a suspension of 3 as prepared
above (0.20 g, 0.39 mmol) in ethanol (10 ml) and the
reaction mixture was stirred at r.t. for 1 h. The solvent
was removed in vacuo, water (3 ml) was added and the
residue was extracted with diethyl ether (3×5 ml). The
combined extracts were dried (Na2SO4) and the solvent
removed in vacuo to afford 4 as a yellow oil (0.18 g,
95%). 1H-NMR (C6D6): l 0.66–2.19 (38H, m, both
isomers), 1.05 (3H, d, minor isomers), 1.08 (3H, d,
major isomer), 1.86 (6H, s, major isomer), 1.92 (6H, s,
minor isomer), 3.22 (1H, q, minor isomer), 3.49 (1H, q,
major isomer), 6.46 (1H, s, minor isomer) (J(1H–119Sn)
1904 Hz), 6.46 (1H, s, major isomer) (J(1H–119Sn) 1920
Hz), 7.00–7.85 (18H, m both isomers). 13C-NMR
(C6D6): major diastereomer: l 13.31, 16.08, 22.11,
22.81, 27.06, 34.10, 35.41 (J(13C–119Sn) 456 Hz), 35.67,
35.98, 40.82 (2C), 42.92, 46.41, 64.64, 126.79, 126.89,
128.36 (2C), 128.39, 128.78, 137.89, 138.14, 140.83
(J(13C–119Sn) not observable), 144.15 (J(13C–119Sn)
387 Hz), 150.54; minor diastereomer: l 11.23, 16.00,
22.04, 22.78, 27.06, 33.39, 35.90, 35.98 (J(13C–119Sn)
484 Hz), 36.09, 40.26 (2C), 42.15, 46.78, 63.37, 126.34,
126.75, 128.07 (2C), 128.39, 128.53, 138.05 (2C), 138.38,
140.94 (J(13C–119Sn) not observable), 144.33 (J(13C–
119Sn) 359 Hz), 150.29. 119Sn-NMR (C6D6): major
1
solid (0.58 g, 20%); m.p. 65–72°C. H-NMR (CDCl3):
l −0.28–2.07 (38H, m), 2.76 (3H, s), 2.88 (3H, s),
7.37–8.35 (10H, m). 13C-NMR (CDCl3): l 14.62, 16.60,
21.38, 21.89, 22.30, 22.64, 26.34, 26.59, 30.95, 34.30,
34.75 (2C), 35.37, 35.53, 40.64, 42.12, 42.92 (J(13C–
119Sn) 474 Hz), 44.12 (J(13C–119Sn) 482 Hz), 44.24,
44.42, 48.51, 50.12, 115.70, 125.01, 127.20 (2C), 128.26,
134.41, 135.07, 136.42, 140.05 (J(13C–119Sn) 467 Hz),
150.76. 119Sn-NMR (CDCl3): l −49.6. Anal. Calc. for
C32H50ClNSn: C, 63.8; H, 8.4; N, 2.3. Found: C, 63.4;
H, 7.9; N, 2.2%.
3.2.7. Men2LSnH (7)
A solution of 6 (0.42 g, 0.70 mmol) in diethyl ether
(25 ml) was added to a suspension of LiAlH4 (0.08 g,
4.61 mmol) in diethyl ether (50 ml). The reaction mix-
ture was stirred at r.t. for 18 h. Water (1 ml) was
cautiously added. The reaction mixture was filtered and
a 20% potassium/sodium-(+)-tartrate solution (30 ml)
was added. The residue was extracted with diethyl ether
(3×30 ml), dried (Na2SO4) and the solvent removed in
vacuo to yield a cream coloured oil (0.36 g, 86%).
1H-NMR (C6D6): l 0.40–2.17 (38H, m), 2.44 (3H, s),
2.48 (3H, s), 6.31 (1H, s), 6.99–8.01 (10H, m). 13C-
NMR (C6D6): l 15.97, 16.47, 22.40, 22.46, 22.96, 23.03,
27.44 (2C), 32.77, 34.13, 35.02 (J(13C–119Sn) 475 Hz),
35.84, 36.04, 36.10, 36.15, 36.75 (J(13C–119Sn) 389 Hz),
42.23, 43.70, 46.33, 47.79 (2C), 47.96, 116.18, 125.57,
125.90, 125.94, 129.28, 135.15, 135.63, 136.93, 138.83
(J(13C–119Sn) 442 Hz), 152.48. 119Sn-NMR (C6H6): l
−104.6 (d, J(119Sn–1H) 1729 Hz). HRMS (ESI): m/z
Calc. for C32H49NSn [M−H]+: 568.2953. Found:
568.2967.
diastereomer:
l
(Rint, %) −136.7 (64); minor
diastereomer: l (Rint, %) −166.8 (36). HRMS (ESI):
m/z Calc. for C26H38SnN [M−H]+: 484.2017. Found:
484.2014.
3.2.5. Men2SnCl2 (5)
A solution of HgCl2 (4.99 g, 18.38 mmol) in acetone
(100 ml) was added slowly to a solution of Men2Ph2Sn
(5.06, 9.18 mmol) in acetone (100 ml) at 0°C. The
reaction mixture was stirred at r.t. for a further 18 h.
The solvent was removed in vacuo and the PhHgCl was
removed by precipitation from diethyl ether. The
residue was distilled (180°C, 1 Pa), to give 5 as a
colourless oil which solidified on standing (3.47 g, 81%);
1
m.p. 43–45°C. H-NMR (CDCl3): l 0.83–2.33 (38H,
3.2.8. Men2L*SnCl (8)
m). 13C-NMR (CDCl3): l 15.9, 21.9, 22.2, 26.7, 34.5,
35.3, 36.7, 38.9, 45.8, 52.6 (J(13C–119Sn) 385 Hz). 119Sn-
NMR (CDCl3): l 94.3. Anal. Calc. for C20H38Cl2Sn: C,
51.3; H, 8.2. Found: C, 51.3; H, 8.0%.
A solution of LiL* (1.26 g, 8.12 mmol) in diethyl
ether (30 ml) was added to a solution of 5 (3.39 g, 7.24
mmol) in diethyl ether (20 ml) at 0°C, and the reaction
stirred at r.t. for 18 h. Saturated NH4Cl (2 ml), and
water (50 ml) were added to the reaction mixture. The
mixture was extracted with dichloromethane (2×30
ml), the combined extracts dried (Na2SO4) and the
solvent removed in vacuo. The residue was triturated
with methanol to give 8 a white crystalline solid (3.33 g,
3.2.6. Men2LSnCl (6)
A suspension of LiL·etherate (1.33 g, 5.32 mmol) in
diethyl ether (25 ml) was added to a solution of 5 (2.30
g, 4.91 mmol) in diethyl ether (25 ml) at 0°C, and the

D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
219
1
79%); m.p. 183–187°C. H-NMR (CDCl3): l 0.07–2.06
35.86 (J(13C–119Sn) 431 Hz), 35.98, 36.04, 36.07, 41.32
(2C), 42.30, 43.73, 47.15, 47.75, 65.30, 126.22, 126.73,
128.12, 138.30, 142.58 (J(13C–119Sn) 430 Hz), 151.36.
119Sn-NMR (C6D6): l −141.3 (d, J(119Sn–1H) 1688
Hz). HRMS (ESI): m/z Calc. for C30H52NSn [M−H]+:
546.3109. Found: 546.3112.
(38H, m), 1.41 (3H, d), 2.25 (6H, s, broad), 4.12 (1H,
q), 7.17–8.06 (4H, m). 13C-NMR (CDCl3): l 7.87,
15.29, 16.40, 21.49, 21.87, 22.37, 22.57, 26.43, 26.67,
30.88, 34.42, 34.85 (2C), 35.30, 35.42, 40.13 (broad)
(2C), 40.92, 41.08 (J(13C–119Sn) 462 Hz), 41.94, 44.12,
44.96, 45.06 (J(13C–119Sn) 515 Hz), 61.75, 124.69,
127.28, 128.15, 136.53, 145.05 (J(13C–119Sn) 488 Hz),
146.55. 119Sn-NMR (CH2Cl2): l −75.2. Anal. Calc. for
C30H52ClNSn: C, 62.0; H, 9.0; N, 2.4. Found: C, 62.0;
H, 9.3; N, 2.2%.
3.2.10. MenPh2LSn (10)
A suspension of LiL·etherate (1.50 g, 6.20 mmol) in
diethyl ether (50 ml) was added to a suspension of
MenPh2SnF (0.74 g, 1.72 mmol) in diethyl ether (10 ml)
at 0°C. The reaction mixture was stirred at r.t. for 60 h,
after which the solvent was removed in vacuo. The
residue was purified by column chromatography (silica
gel 60, 70–230 mesh) using a 20:80 solution of
dichloromethane–hexane to afford 10 as a white solid
(0.38 g, 32%); m.p. 82–85°C. 1H-NMR (CDCl3): l
0.31–2.21 (19H, m), 1.87 (3H, s), 2.66 (3H, s), 7.24–
7.86 (16H, m). 13C-NMR (CDCl3): l 16.75, 21.56,
22.68, 26.94, 33.45, 35.40, 35.61, 36.60 (J(13C–119Sn)
509 Hz), 40.92, 45.12, 45.85, 50.40, 115.52, 125.48,
125.83, 125.93, 127.55, 127.74 (2C), 128.07 (2C), 128.15
(2C), 128.44 (2C), 135.22 (J(13C–119Sn) 537 Hz), 143.68
(J(13C–119Sn) 493 Hz), 145.23 (J(13C–119Sn) 360 Hz),
3.2.9. Men2L*SnH (9)
A solution of 8 (0.63 g, 1.09 mmol) in diethyl ether
(20 ml) was added to a suspension of LiAlH4 (0.70 g,
18.4 mmol) in diethyl ether (30 ml) and the mixture was
stirred at r.t. for 18 h. The reaction mixture was filtered
through a thin layer of filter aid and water (3 ml) was
added carefully to the filtrate at 0°C. Sodium/potas-
sium-(+/−)-tartrate (20%, 20 ml) was added and the
product was extracted with diethyl ether (2×30 ml).
The combined extracts were dried (Na2SO4) and the
solvent removed in vacuo to yield 9 as a pale yellow oil
1
(0.46 g, 78%). H-NMR (C6D6): l 0.81–2.28 (38H, m),
1.15 (3H, d), 2.05 (6H, s), 3.56 (1H, q), 5.99 (1H, s,
J(1H–119Sn) 1671 Hz), 7.13–7.72 (4H, m). 13C-NMR
(C6D6): l 13.64, 16.12, 16.24, 22.26, 22.31, 22.85, 22.89,
27.20, 27.29, 33.72 (2C), 35.61 (J(13C–119Sn) 362 Hz),
119Sn-NMR (C6H6):
l
−107.1. Anal. Calc for
C34H41NSn·CHCl3: C, 59.9; H, 6.0; N, 2.0. Found: C,
60.7; H, 6.4; N, 1.8%.
Table 4
Crystallographic data for MenPhL*SnCl (3), Men2L*SnCl (8) andMenPh2LSn (10·2CHCl3)
3
8
10·2CHCl3
Formula
Fw
C26H38ClNSn
518.7
C30H52ClNSn
580.9
C36H41Cl6N2Sn
833.1
Crystal size (mm)
Colour
Temperature (K)
Crystal system
Space group
0.11×0.27×0.47
Colourless
293
Triclinic
P1
0.26×0.26×0.52
Colourless
200
Orthorhombic
P212121
0.13×0.37×0.44
Colourless
200
Monoclinic
P21
,
a (A)
9.53(1)
25.51(2)
9.217(9)
97.69(8)
118.47(7)
84.66(9)
1950(4)
3
1.325
804
10.96
0.282–1
9486
12.866(5)
23.37(2)
10.223(5)
14.480(9)
21.07(1)
12.345(8)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
114.83(4)
3
,
V (A )
3073(2)
4
1.255
1224
9.35
0.691–1
4000
27.7
3418(3)
4
Z
Dcalc (g cm−3
F(000)
)
1.619
1692
12.46
0.855–1
8431
27.6
v (cm−1
)
Transmission factors
No. of data collected
qmax (°)
27.6
No. of unique data with I]3.0|(I)
R
5520
0.080
0.088
1.83
3587
0.025
0.032
0.36
6172
0.048
0.050
1.20
Rw
−3
,
Residual electron density (e A
)

220
D. Dakternieks et al. / Journal of Organometallic Chemistry 605 (2000) 209–220
3.2.11. Men2PhLSn (11)
A solution of LiL·etherate (1.51 g, 6.04 mmol) in
TMEDA (50 ml) was added to solution of
CCDC No. 141614 for compound 8, and CCDC No.
141616 for compound 10. Copies of the information
may be obtained free of charge from: The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
a
Men2PhSnI (2.30 g, 3.83 mmol) in TMEDA (40 ml)
and the solution was stirred at r.t. for 15 h. Water (1
ml) was added, the solution was dried (MgSO4) and the
solvent removed in vacuo. Purification of the residue
was achieved by column chromatography (silica gel 60,
70–230 mesh) using a 70:30 solution of hexane–
dichloromethane. Crystallisation in hot methanol af-
forded a white solid (0.83 g, 33%); m.p. 155°C.
1H-NMR (CDCl3): l 0.38–2.24 (38H, m), 2.47 (3H, s),
2.76 (3H, s), 7.24–7.84 (11H, m). 13C-NMR (CDCl3): l
16.13, 17.16, 21.74, 21.84, 22.49, 22.77, 27.06, 27.20,
32.58, 33.69, 35.32, 35.54, 35.57, 35.68, 36.94 (J(13C–
119Sn) 439 Hz), 37.62 J(13C–119Sn) 407 Hz), 40.80,
43.29, 45.32, 46.32, 46.48, 50.98, 115.34, 125.02, 125.37,
125.95, 126.88, 127.23 (2C), 128.27, 135.01, 135.86,
137.56 (2C), 137.87, 138.67 (J(13C–119Sn) 431 Hz),
147.48 (J(13C–119Sn) 295 Hz), 153.44. 119Sn-NMR
(CHCl3): l −99.1 Anal. Calc. for C38H55NSn: C, 70.8;
H, 8.6; N, 2.2. Found: C, 70.6; H, 8.6; N, 2.0%.
Acknowledgements
We gratefully acknowledge the Australian Research
Council for financial support.
References
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Data were collected on a Rigaku AFC6R diffrac-
tometer fitted with graphite monochromatised Mo–Ka
,
radiation, u=0.71073 A. Corrections were made for
Lorentz and polarisation effects [23] as well as for
absorption employing an empirical method [24]. The
structures were solved by Patterson methods [25] and
each refined by a full-matrix least-squares procedure
based on F [23]. The absolute structures were deter-
mined on the basis of the known configuration of the
menthyl. For the refinement of 8 all non-hydrogen
atoms were refined with anisotropic displacement
parameters but for the refinements of 3 and 10 only
non-carbon and non-hydrogen atoms were refined an-
isotropically. The refinements were continued with the
application of a weighting scheme of the form w=1/
2
[|2(Fo)+gꢀFoꢀ ] where g=0.00022, 0.00018 and 0.019
for 3, 8 and 10, respectively. The significant residual
electron density peaks (Table 4) in the final difference
maps were located in the region of the tin atom in each
case. Crystallographic and refinement data are given in
Table 4. Diagrams of the molecules were drawn with
ORTEP [26] plotted at the 35% (for 3) and 50% (for 8
and 10) probability levels.
[23] TEXSAN
: Structure Analysis Software, Molecular Structure
Corp., The Woodlands, TX, USA.
[24] N. Walker, D. Stuart, Acta Crystallogr. Sect. A 39 (1983) 158.
[25] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, S.
Garcia-Granda, J.M.M. Smits, C. Smykalla, The DIRDIF Pro-
gram System, Technical Report of the Crystallography Labora-
tory, University of Nijmegen, The Netherlands, 1994.
[26] C.K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, TN, 1976.
4. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 141615 for compound 3,
.