Rock around the ring: An experimental and theoretical study of the molecular dynamics of stannyltriphospholes with chiral tin substituents

Article abstract of DOI:10.1002/ejic.200701321

The reaction of diphenyltin dichloride with enantiopure Grignard reagents prepared in situ leads to diphenyltin chlorides 7a-e, which contain chiral organyl substituents. The 2-bornyl derivative 7a forms a mixture of exo and endo isomers and the (-)-menthyl derivative 7b yields a mixture of epimers, whereas the cis- and trans-myrtanyl complexes 7c and 7d and the m-(2-bornyl-2-ene)phenyl species 7e form only one enantiomer as the tin atom is separated from the next stereogenic centre by a methylene or m-phenylene group. The target chirally modified 1-(triorganylstannyl)-1,2,4-triphospholes 2a-e are accessible from 7a-e by treatment of the latter with the salt (3,5-di-tert-butyl-1,2,4- triphospholyl)-sodium (Na5) in good yield. As for 7c-e, complexes 2c-e exhibit enantiopure organyl tin substituents that combine with the planar chiral 1,2,4-triphosphole moiety to form diastereomers. X-ray diffraction studies on crystalline phases of 2a,b,d and 7b,c confirm the stereochemical interpretations of their spectroscopic data with the help of absolute structure parameter determinations. Dynamic NMR spectroscopy experiments with these compounds demonstrate for the first time a facile stannyl group shift between the two adjacent P atoms (P1 and P2) of the heterocycles that includes ring inversion through a planar transition state (T₁). In line with the NMR spectroscopic results for 2a-e, density functional calculations with the simplified model compound (trimethylstannyl)-1,2,4-triphosphole (9) point to 1-(trimethylstannyl)-1,2,4-triphosphole (9a) as the global energetic minimum for 9 and an almost isoenergetic 1,2-shift and ring inversion as the main epimerisation processes of the two enantiomers of 9a. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200701321

FULL PAPER
DOI: 10.1002/ejic.200701321
Rock around the Ring: An Experimental and Theoretical Study of the
Molecular Dynamics of Stannyltriphospholes with Chiral Tin Substituents
Martin Hofmann,[a] Tim Clark,[b] Frank W. Heinemann,[a] and Ulrich Zenneck*[a]
Keywords: Phosphorus heterocycles / Tin / Stereochemistry / Molecular dynamics / Density functional calculations
The reaction of diphenyltin dichloride with enantiopure
Grignard reagents prepared in situ leads to diphenyltin chlo-
rides 7a–e, which contain chiral organyl substituents. The 2-
bornyl derivative 7a forms a mixture of exo and endo isomers
and the (–)-menthyl derivative 7b yields a mixture of epi-
mers, whereas the cis- and trans-myrtanyl complexes 7c and
7d and the m-(2-bornyl-2-ene)phenyl species 7e form only
one enantiomer as the tin atom is separated from the next
stereogenic centre by a methylene or m-phenylene group.
The target chirally modified 1-(triorganylstannyl)-1,2,4-tri-
phospholes 2a–e are accessible from 7a–e by treatment of the
latter with the salt (3,5-di-tert-butyl-1,2,4-triphospholyl)-
sodium (Na5) in good yield. As for 7c–e, complexes 2c–e ex-
hibit enantiopure organyl tin substituents that combine with
the planar chiral 1,2,4-triphosphole moiety to form dia-
stereomers. X-ray diffraction studies on crystalline phases of
2a,b,d and 7b,c confirm the stereochemical interpretations of
their spectroscopic data with the help of absolute structure
parameter determinations. Dynamic NMR spectroscopy ex-
periments with these compounds demonstrate for the first
time a facile stannyl group shift between the two adjacent P
atoms (P1 and P2) of the heterocycles that includes ring in-
version through a planar transition state (Ti). In line with the
NMR spectroscopic results for 2a–e, density functional calcu-
lations with the simplified model compound (trimethylstan-
nyl)-1,2,4-triphosphole (9) point to 1-(trimethylstannyl)-1,2,4-
triphosphole (9a) as the global energetic minimum for 9 and
an almost isoenergetic 1,2-shift and ring inversion as the
main epimerisation processes of the two enantiomers of 9a.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
1,2,4-triphosphole (1), for example (Figure 1), although the
symmetry of the exchange process means that the experi-
mental data do not indicate whether the tin always stays on
the same side of the ring or if it also moves to the other
side.[7] In the former the stannyl group would oscillate be-
tween the two adjacent phosphorus atoms like a windscreen
wiper, whereas in the latter it rocks around the P2 edge of
1 or maybe even around the complete π-system of the mole-
cule. Besides simply shifting the substituent to the other P
atom through a triangular η2 transition state, the wind-
screen-wiper mode could also include a ring-slippage
mechanism via η1-η3-η5 bonding of the tin atom, as ob-
served earlier for nickel,[9] although in this case an inversion
of the pyramidal phosphorus atom would be excluded. This
assumption follows a general feature of P-chiral phos-
phanes, which can exist as a pair of stable enantiomers at
ambient temperatures.[10,11] A well characterised example of
the inversion barrier at a phosphorus[12] or arsenic centre
Introduction
The fluxional behaviour of cyclopentadiene and its deriv-
atives has been a subject of interest for several groups since
1970.[1–3] A similar dynamic molecular behaviour can be
observed when one or more of the CH fragments of cyclo-
pentadiene are replaced by isolobal phosphorus atoms to
form mono-, di-, tri- or tetraphospholes.[4–6] If a λ3-phos-
phorus atom of a phosphole is bonded to a metallic group
14 or another p-block element, a diene-like character of the
five-membered heterocycle results because of the covalent
character of the P–M bond.[7,8] As the dynamic behaviour
of phospholes involves reversible forming and breaking of
P–M and probably of C–M bonds, it also reveals details
of the bonding situation in the heterocycles. A facile [1,5]-
sigmatropic shift has been observed by dynamic NMR
spectroscopy for the SnPh3 group of 1-(triphenylstannyl)-
[a] Department Chemie und Pharmazie and Interdisciplinary Cen- in a five-membered ring exists,[13] and the energy barriers in
ter for Molecular Materials, Universität Erlangen-Nürnberg,
these cases are anticipated to be much higher than for the
Egerlandstr. 1, 91058 Erlangen, Germany
Fax: +49-9131-852-7367
E-mail: ulrich.zenneck@chemie.uni-erlangen.de
[b] Computer-Chemie-Centrum der Universität and Interdisciplin-
ary Center for Molecular Materials,
triphospholyl system.
If d8- or d10-transition metal ions like Ni2+ [14]
,
Pt2+ [15]
,
Cu+,[16] Ag+,[17] or Au+ [18] are bound to a formal 1,2,4-tri-
phospholyl anion, the metal atom may be coordinated by a
P-atom lone pair of a planar and aromatic ring ligand. This
bonding situation is equivalent to that of a potential inver-
sion transition state for a P substituent that changes sides
Nägelsbachstrasse 25, 91054 Erlangen, Germany
Fax: +49-9131-852-6565
E-mail: tim.clark@chemie.uni-erlangen.de
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2008, 2225–2237
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M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
FULL PAPER
Figure 1. [1,5]-Sigmatropic shift of the SnPh3 group of 1.
of a phosphole derivative. Phosphole transition metal com- phases of crystallographic quality. The chiral group is pref-
plexes of Ti4+, Zr4+ and Hf4+ have been shown to exhibit erably introduced with the help of Grignard reagents
fluxional behaviour using their chiral planarity, and the formed from the corresponding chlorides R*Cl (R* should
change of ring face of the substituent was confirmed by not contain functional groups to avoid unwanted side reac-
facile isomerisation at ambient temperature to form rac and tions). Another problem is the danger of epimerisation of
meso isomers.[19] Even more closely related to other main the α-carbon atoms linked to tin. Thus, bornyl and menthyl
group element substituents, the bulky CH(SiMe3)2 group chlorides and compounds 8c–8e, which contain methylene
generates planar 1-CH(SiMe3)2-3,5-di-tBu-1,2,4-triphos- or m-phenylene spacer groups, were used to prevent loss of
phole if attached to one of the neighbouring phosphorus optical activity (Scheme 1).
atoms by a covalent P–C bond.[20] The occurrence of planar
P atoms has also been attributed to electronic effects.[21]
In this paper we report an experimental and theoretical
investigation of the mobility of the stannyl groups of P-
chiral 3,5-di-tert-butyl-1-(triorganylstannyl)-1,2,4-triphos-
pholes. To allow the observation of a change of face of the
tin atom through phosphorus atom inversion by NMR
spectroscopy, a chiral Sn substituent is required to trans-
form the two enantiomers of 1 into a pair of diastereomers
2. The target asymmetrically substituted 1-stannyl-1,2,4-tri-
phospholes are also relevant to an interesting preparative
question: a high-yield, highly diastereoselective cycload-
dition reaction of 1 with two equivalents of the P-alkyne
tBuCϵP gives access exclusively to one pair of enantio-
meric P5(CR)4(SnR3) cage compounds with seven stereo-
genic centres.[7] Control of the stereochemistry of such cage-
forming processes is one of the main objectives of this re-
search. To the best of our knowledge, no asymmetric P–C
cage compounds with a defined stereochemistry are known.
We regard such compounds as novel chiral building blocks
with several potential uses, for instance as ligands in enan-
tioselective catalysis or in materials science.
Scheme 1. The chiral organyl chlorides used in this study.
Chiral Organyl Chlorides R*Cl
Compound 8a is accessible by addition of HCl to α-pi-
nene at low temperature followed by a Wagner–Meerwein
rearrangement.[25] NMR spectroscopy reveals the presence
of about 10% of the endo isobornyl chloride as an impurity,
which could not be removed.[26] (1R)-(–)-Menthyl chloride
(8b) is available commercially. The optically active alcohols
(–)-cis- and (–)-trans-myrtanol were transformed into the
corresponding chloro compounds 8c and 8d by a standard
substitution reaction sequence.[27] To prepare a closely re-
lated chiral derivative of 1-(triphenylstannyl)-1,2,4-triphos-
phole (1), which was investigated in most detail, 2-(m-chlo-
rophenyl)bornyl-2-ene (8e) was synthesised from 1-bromo-
3-chlorobenzene and (+)-camphor (Scheme 2).[28]
Results and Discussion
Becker et al. have shown that reduction of the stable
phosphaalkene Me3SiP=C(OSiMe3)(tBu) (3) with elemen-
tal alkali metals (M) or suitable metal–organic compounds
(MR) leads to a mixture of the salts M(2,4,5-tri-tert-butyl-
1,3-diphospholyl) (M4) and M(3,5-di-tert-butyl-1,2,4-tri-
phospholyl) (M5) as the main products.[22–24] Such mixtures
can be separated by repeated fractional crystallisation of
the sodium salts from thf. 1-Triorganylstannyl-1,2,4-tri-
phospholes are accessible from the sodium salt Na5 upon
treatment with the corresponding triorganyltin chloride
(R3SnCl, 6).[7]
One chiral group is sufficient to apply this approach to
formation of the asymmetrically substituted Ph2R*SnCl de-
rivatives 7. Phenyl groups have been chosen as co-substitu-
ents because of their supporting role in forming solid Scheme 2. Preparation of 2-(3-chlorophenyl)bornyl-2-ene (8e).
2226 Eur. J. Inorg. Chem. 2008, 2225–2237
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Stannyltriphospholes with Chiral Tin Substituents
Chirally Modified Triorganyltin Chlorides
pendent molecules of one enantiomer in the asymmetric
part of the unit cell; two others are symmetry related and
the structural differences between the two independent
molecules are only marginal (Table 1). The crystal packing
of 7b is characterised by individual stacks of independent
molecules along the crystallographic b axis that exhibit
short Cl···Sn distances of 369 pm between neighbouring
molecules. This stacking results in infinite almost linear
Cl···Sn–Cl···Sn chains with an Sn···Cl–Sn angle of 170°.
The organyl chlorides 8a–e were transformed into the
corresponding Grignard compounds by treatment with ac-
tivated magnesium[29] and then treated with Ph2SnCl2 to
afford the Ph2SnR*Cl derivatives 7a–e in yields of about
40% after chromatographic purification to remove unre-
acted starting material and disubstituted by-product
Ph2SnR*2 (Scheme 3).[30]
Table 1. Selected Sn–C, C–C and Sn–Cl distances [pm] and angles
[°] for triorganyltin chlorides (R)-7b and 7c.
(R)-7b
(molecule 1) (equiv.
positions
(R)-7b
7c
molecule 2)
Sn1–Cl
Sn1–C1
Sn1–C11
Sn1–C21
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
240.4(5)
214(1)
214(1)
213(1)
165(2)
139(2)
159(2)
159(2)
146(2)
147(2)
100.0(4)
116.1(5)
121.4(5)
239.6(7)
214(2)
216(2)
213(2)
169(2)
133(2)
157(2)
158(2)
142(2)
148(2)
101.1(6)
113.4(6)
125.0(6)
110.8(5)
101.0(5)
100.8(5)
110(2)
121(2)
109(2)
122(2)
107(2)
115(2)
239.52(4)
213.4(2)
214.2(2)
212.9(2)
C2–C3 155.4(2)
C3–C4 155.4(3)
C4–C5 152.5(3)
C5–C6 154.4(3)
C6–C7 155.2(2)
C7–C2 153.6(3)
106.10(4)
C6–C1
C1–Sn1–Cl1
C1–Sn1–C11
C1–Sn1–C21
112.63(6)
118.97(7)
116.20(6)
100.94(5)
C11–Sn1–C21 111.9(4)
Scheme 3.
C11–Sn1–Cl1
C21–Sn1–Cl1
C6–C1–C2
C1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–C6
C5–C6–C1
102.0(4)
100.8(5)
108(2)
117(2)
108(2)
111(2)
106(2)
116(2)
98.35(5)
In the case of 7a, only an oily mixture of exo and endo
isomers was obtained.[31] Compound 7b forms an epimeric
mixture of (R)-7b and (S)-7b,[32,33] with the main epimer
(R)-7b accounting for about 90% of the mixture. Com-
pounds 7c–e were isolated as chemically and optically pure
compounds, and (R)-7b and 7c were structurally character-
ised by X-ray diffraction (Figure 2).
C7–C2–C3 111.3(2)
C2–C3–C4 115.1(2)
C3–C4–C5 112.8(2)
C4–C5–C6 108.2(2)
C5–C6–C7 86.0(2)
C6–C7–C2 107.6(2)
The single-crystal X-ray diffraction studies of (R)-7b and
The single crystal of 7c investigated contains one inde-
7c reveal that they consist of discrete mononuclear mole- pendent molecule in the asymmetric part of the unit cell;
cules in the solid state. Both these compounds crystallise in three more are symmetry related by the three twofold screw
chiral space groups (P21 for 7b and P212121 for 7c) which axes of the space group. Similar to 7b, the crystal packing of
are composed of a single enantiomer of the corresponding 7c is characterised by relatively short intramolecular Cl···Sn
molecules [absolute structure parameter x = 0.16(10) for 7b distances of 368 pm between neighbouring molecules,
and –0.03(1) for 7c].[34] Compound 7b contains two inde- which results in the formation of stacks along the crystallo-
Figure 2. Molecular structures of (1R)-(–)-menthyldiphenyltin chloride [(R)-7b, left] and (–)-cis-myrtanyldiphenyltin chloride (7c, right)
in the solid state.
Eur. J. Inorg. Chem. 2008, 2225–2237
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M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
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graphic b axis. In contrast to (R)-7b, however, molecules of ation of compounds 2c,d,e (Scheme 4), all of which show
1
7c are arranged in a zigzag fashion with an Sn···Cl–Sn angle only one set of H, 13C and 31P NMR signals and are op-
of 124° in the resulting Cl···Sn–Cl···Sn chains. Both these tically active.
compounds are therefore triorganyltin chlorides with ex-
panded C–Sn–C and reduced C–Sn–Cl angles compared to
an ideal tetrahedral arrangement of Sn substituents
(Table 1). This effect is more pronounced for (R)-7b due to
direct bonding of the tin atom to the chiral cycle.
As hoped for, the stereochemistry of the chiral organic
substituents of (R)-7b and 7c remains unchanged in com-
parison to the starting materials 8b and 8c. The C–C bond
lengths for the menthyl groups of the two independent
molecules of (R)-7b span the range from 133 to 168 pm and
Scheme 4. Preparation of diastereomeric 3,5-di-tert-butyl-1-(tri-
organylstannyl)-1,2,4-triphospholes 2a–e.
the C–C–C bond angles vary from 106° to 122°. The rela-
The molecular structures of 2a,b,d in the solid state are
tive trends within the aliphatic rings are the same for both
shown in Figures 3, 4 and 5, respectively, and selected bond
compounds: the highly Ph2SnCl-influenced C1–C2 bonds
angles and lengths are given in Table 2. Compounds 2a,b,d
and their counterparts in molecule 2, for example, exhibit
exhibit some general structural features that are similar to
the Ph3Sn derivative 1,[7] such as the pyramidality of the λ3-
phosphorus atoms, which is characterised by the sum of the
bond angles around P1 [ΣՄP1]. The two enantiomers of 1
the significantly elongated distances of 165 and 169 pm,
whereas all the other C–C bonds are shorter then 160 pm.
Due to a smaller interaction between the stannyl group and
the aliphatic cis-myrtanyl moiety because of the methylene
have values of 310.3°, whereas all enantiomers and epimers
linker, the intra-ring C–C myrtanyl bond lengths of 7c fall
of 2a,b,d characterised structurally in this study exhibit val-
in the range 152 to 157 pm whereas the C–C–C angles vary
ues of between 292.9° and 312.6° (Table 2). Consistent with
from 84° to 115°. All values below 90° belong to internal
this observation, the triphosphole moieties form almost
C–C–C bond angles of the four-membered ring substruc-
planar P=C–P=C trapezoids with alternating P–C bond
lengths. The λ3-P centre is only slightly displaced from this
plane opposite to the side of the tin atom to form envelope-
type conformers of the five-membered rings. These findings
give a clear indication of localised π4-systems and a pyrami-
dal phosphorus atom as a linker which is not involved in π-
interactions with the neighbouring sp2-hybridized ring car-
bon and phosphorus atoms. A significant influence of the
chiral tin substituents on the bonding situation of the tri-
phosphole ring can be ruled out.
ture; the others fall in the range 107–115°. In both cases,
the molecular structure parameters of the aliphatic chiral
groups agree with earlier findings for related compounds,[35]
therefore (R)-7b and 7c exhibit no unusual strain within the
molecules.
Diastereomeric 1-(Triorganylstannyl)-1,2,4-triphospholes
2a–e
The specific structural features of the molecules in the
Treatment of the triorganyltin chlorides 7a–e with 3,5-
di-tert-butyl-1,2,4-triphospholylsodium (Na5) in toluene at
–30 °C led to formation of the target diastereomeric 1-
(triorganylstannyl)-3,5-di-tert-butyl-1,2,4-triphospholes 2a–
e in yields of up to 80%. Compounds 2a,b,d were isolated
as yellow crystals that proved to be suitable for X-ray dif-
fraction studies, whereas 2e was isolated as an amorphous
solid and 2c as a yellow oil.
solid state are as follows. The exo-bornyl derivative 2a crys-
¯
tallises in the centrosymmetric space group P1. The two
molecules in the unit cell form a racemic mixture of two
enantiomers that are crystallographically connected by an
inversion centre (Figure 3). One and a half molecules of tol-
As indicated by the properties of the isomeric bornyl
chloride 7a, a double set of signals with an intensity ratio
of about 2:1 in the NMR spectra of bornyl derivative 2a
proves the loss of at least one stereogenic centre. As no
optical activity at all remained from the starting α-pinene,
a complete racemisation of the norbornyl group is assumed
to form a mixture of bornyl and isobornyl derivatives[25]
(see below). Both these compounds exist as diastereomers
in rapid equilibrium with the two enantiomeric stannyl-
1,2,4-triphosphole units. A double set of NMR signals in
the same 9:1 ratio as for the (R)-7b/(S)-7b starting material
in the menthyl derivative 2b suggests that no further epi-
merisation of the menthyl group takes place upon connect-
ing the tin atom to the heterocycle. The spectroscopic in-
Figure 3. Molecular structure of one of the enantiomers of racemic
exo-derivative 2a in the solid state. Solvent molecules and hydrogen
vestigations gave no indication of epimerisation or racemis- atoms have been omitted for clarity.
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Stannyltriphospholes with Chiral Tin Substituents
the crystallographic c-direction, and four of these stacks at
the unit cell edges form a channel that is occupied by the
toluene solvent molecules. All bond lengths and angles of
the aliphatic exo-bornyl substituent are in the normal range
of values for derivatives, with no significant distortion.[36]
Crystals of 2b of sufficient quality for X-ray diffraction
studies were only obtained for a crystalline phase composed
of a 1:1 mixture of the two epimers already observed for
stannyl chloride 7b. The main epimer can only be isolated
as an amorphous solid and attempts to separate the solid
phases of 2b by fractional crystallisation failed. Compound
2b crystallises in the chiral space group P1 [absolute struc-
ture parameter x = 0.015(16)][34] with two independent
molecules in the unit cell that represent two diastereomers
with opposite stereodescriptors for P3 (S) and P5 (R) and
C30 (R) and C80 (S), the menthyl group stereogenic centre
that is partially lost by the tin-α-Cmenthyl interaction (Fig-
ure 4). The other two stereogenic centres of the menthyl
group (C32–C35 and C82–C85) remain unaffected by all
chemical procedures that eventually lead to 2b. The two
phenyl tin substituents of two neighbouring independent
epimers are involved in weak T-shaped π-stacking interac-
tions in the crystalline phase. The corresponding C(H)··· π
distances are 362 and 368 pm.
As intended, the introduction of achiral spacer groups
like methylene or m-phenylene between the tin atom and
the next stereogenic centre prevents epimerisation or racem-
isation of the chiral organyl group of compounds 2c,d,e
completely. The structure of trans-myrtanyl species 2d was
determined by X-ray diffraction (Figure 5). This compound
crystallises in the chiral space group P21 with two indepen-
dent molecules in the asymmetric part of the unit cell.
Figure 4. Molecular structures of two epimers of 2b (SR; top, equa-
torial) and 2b (RS; bottom, axial) in the solid state. Hydrogen
atoms have been omitted for clarity.
uene are also present per formula unit. The single toluene These two molecules are diastereomers with the tin atom
molecule occupies a specific position in the unit cell bound to either of the two adjacent diastereotopic (R)- and
whereas the half molecule is disordered around the crystal- (S)-phosphorus centres but with identical stereochemistry
lographic inversion centre. No hydrogen atom positions as- [the same as that of the starting material (–)-trans-myrtanol]
sociated with this molecule were determined. The inversion of the chiral auxiliary group [absolute structure parameter
relation between the two observed enantiomers of 2a proves x = 0.009(11)].[34] These two epimeric molecular structures
a complete racemisation of the bornyl group with its three represent the start and end points of the [1,5]-sigmatropic
stereogenic centres at C30, C32, and C35 and the presence stannyl shift in 2b. As the closest stereogenic centres are
of both (R)- and (S)-P1. Molecules of 2a form stacks along separated by three bonds, epimerisation of the λ3-phospho-
Figure 5. Molecular structure of the two diastereomers 2d (SS, left) and 2d (RS, right) in the solid state. Hydrogen atoms have been
omitted for clarity.
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M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
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Table 2. Selected bond lengths [pm] and angles [°] for racemic 2a, epimeric 2b (SR)/(RS), diastereomeric 2d (SS)/(RS), and calculated
values of the energetic minimum species 9a (R1 = R2 = R* = Me).[a]
2a
2b(SR)
2b(RS)
2d(SS)
2d(RS)
9a
Sn–P1
254.95(9)
217.0(3)
214.1(3)
214.7(3)
177.3(3)
171.7(3)
176.5(4)
171.9(3)
213.2(2)
119.6(2)
107.87(9)
105.4(1)
101.94(9)
114.8(2)
96.21(4)
101.6(2)
116.6(2)
102.1(2)
121.6(2)
97.1(2)
255.9(2)
217.3(6)
212.7(6)
214.3(7)
178.7(6)
173.1(7)
175.9(7)
171.0(6)
215.1(2)
116.5(2)
108.5(2)
107.4(2)
106.0(2)
104.8(2)
87.02(8)
101.1(2)
116.1(4)
103.2(3)
121.2(4)
98.0(2)
257.3(12)
220.5(6)
216.3(7)
216.7(6)
176.9(7)
169.0(7)
178.3(7)
170.3(7)
214.3(3)
110.7(2)
106.0(2)
107.3(2)
109.2(2)
107.0(3)
88.04(8)
99.0(2)
255.1(1)
215.2(3)
215.1(3)
214.8(4)
178.5(4)
170.9(4)
178.5(4)
171.0(4)
213.8(2)
110.7(2)
101.43(9)
109.8(1)
110.6(1)
114.0(2)
93.79(4)
100.8(2)
117.5(2)
101.9(2)
121.2(2)
97.9(2)
254.84(9)
216.1(3)
215.6(3)
214.5(3)
178.9(4)
171.9(4)
177.6(4)
171.7(4)
214.5(2)
116.0(2)
108.08(9)
103.75(8)
115.6(1)
112.0(1)
88.97(4)
100.7(2)
117.4(2)
102.1(2)
121.3(2)
97.9(2)
259.0
214.3
214.7
214.9
179.5
173.2
179.3
173.4
219.9
Sn–C(R*)
Sn–C(R1)
Sn–C(R2)
P1–C1
C1–P3
P3–C2
C2–P2
P2–P1
C(R2)–Sn–C(R*)
C(R2)–Sn–P1
C(R1)–Sn–P1
C(R*)–Sn–P1
C1–P1–Sn
P2–P1–Sn
C1–P1–P2
P3–C1–P1
C1–P3–C2
P2–C2–P3
C2–P2–P1
ΣՄP1
112.6, 111.3, 111.3
106.5
110.0
104.8
101.6
98.2
98.9
121.5
97.8
125.4
119.8(4)
101.6(3)
120.2(4)
99.0(2)
95.7
298.7
312.6
292.9
294.0
308.6
301.7
[a] Experimental data: C(R1) = C(R2) = Cipso of phenyl groups; C(R*) = C of chiral group next to the tin atom. General notation 2x(AB):
A = configuration of λ3-phosphorus atom that carries the stannyl group, B = configuration of the stereogenic centre next to the tin atom
of the chiral auxiliary group.
rus atom does not influence the structural parameters of characterised by AB2X spin systems (X = 117/119Sn) at am-
the myrtanyl group significantly Ϫ only the relative orienta-
tion of these two building blocks of 2b changes, mainly by
rotation around the C–C bonds C30–C31 and C80–C81.
This may be caused by packing effects. Both phenyl substit-
uents of both diastereomers are involved in weak T-shaped
π-stacking interactions in the solid state with C(H)···π-dis-
tances ranging from 355 to 409 pm.
bient temperature with triplets for the A nucleus at around
δ = 325 ppm and doublets close to δ = 160 ppm for the two
B nuclei (2JP,P ≈ 40 Hz) (Figure 6). Both are accompanied
by 117/119Sn satellites with a smaller coupling to the A-nu-
cleus (3JSn,P ≈ 50 Hz) and higher values for B (1JSn,P
≈
350 Hz). The variable-temperature 31P{1H} NMR spectra
of the two spectroscopically distinguishable diastereomers
of 2a, for example, reveal some details. Thus, the A-parts
of both spectra remain almost unchanged on cooling to
–70 °C, with only some line broadening due to increasing
solvent viscosity leading to a loss of the triplet appearance
of the lines at the low-temperature limit of the experiment
(–85 °C). In contrast, the B-parts of the spectra lose their
NMR Spectra and Fluxional Behaviour of Diastereomeric
Stannyltriphospholes
The general appearance of the NMR spectra of 2c,d,e at
ambient temperature is very similar to that of the achiral
version 1[7] except that the chiral groups contribute to the tin satellites at –10 °C due to line broadening caused by
spectra. Unlike 2a,b, all three exhibit one set of signals in slowing down of the [1,5]-sigmatropic shift, their doublet
their 1H, 13C and 31P NMR spectra, which is consistent appearance is no longer visible at –30 °C, and at –70 °C
with the optical purity of the compounds and a highly mo- they are no longer observable at all. These signals do not
bile tin atom with respect to the triphospholyl moiety. The reappear at temperatures down to –85 °C, therefore no
1
solution H NMR spectra, for example, always show only slow-exchange-limit spectra could be obtained and a direct
one sharp resonance for the tBu groups of the heterocycle determination of the coalescence temperature, and thus the
even though they are not equivalent in the solid state. The energy barrier, was not possible. As the 31P NMR spectra
same situation occurs for the 31P NMR spectra, which are of solutions of 1 behave similarly on cooling, the activation
2230
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 2225–2237

Stannyltriphospholes with Chiral Tin Substituents
energy of all derivatives of 2 investigated is estimated to system in both cases. A projection of the cyclic rocking
be close to the value (∆G‡ ≈ 7.5 kcalmol–1) found for this mode of the stannyl group in front of the P2-edge of dia-
compound.[7]
stereomeric 1,2,4-triphospholes 2, as deduced from the dy-
namic NMR spectra, is shown in Figure 7.
Figure 7. Cyclic rocking mode of the mobile stannyl group in front
of the P2-edge of 1-(triorganylstannyl)-1,2,4-triphospholes 2.
Computational Results
Density functional theory (DFT) calculations were per-
formed on the model compound trimethylstannyl-1,2,4-tri-
phosphole (9) in order to analyse the bonding situation of
compounds 1 and 2 and the principal aspects of the mo-
bility of the stannyl group in the vicinity of the 1,2,4-tri-
phosphole ring. The absence of bulky carbon substituents
in the model compound means that the DFT studies em-
phasise the electronic aspects of the molecular dynamics.
All calculations were performed with the Gaussian03
suite of programs[37] and the LANL2DZ basis set with stan-
dard pseudopotentials[38] and an additional set of polarisa-
tion functions[39] (designated LANL2DZ+pol in the follow-
ing). Optimisations and calculations of the normal vi-
brations were carried out using density-functional theory
with the Becke three-parameter/Lee–Yang–Parr hybrid
functional.[40] Single-point calculations were performed on
the B3LYP/LANL2DZ+pol optimised geometries using the
same basis set but with an additional set of polarisation
functions on hydrogen[39] (designated LANL2DZ+2pol in
the following) and at the coupled cluster level including sin-
gle and double excitations[41] and a non-iterative correction
for triples[42] [CCSD(T)]. Minima and transition states were
confirmed as such by calculating their normal vibrations
within the harmonic approximation at the B3LYP/
LANL2DZ+pol level. The energies discussed in the text are
those calculated at the CCSD(T)/LANL2DZ+2pol level
corrected for zero-point vibrational energy using the un-
scaled zero-point energies calculated at the B3LYP/
LANL2DZ+pol level.
Figure 6. 31P{1H} NMR spectrum (121.49 MHz, CDCl3, 25.1 °C)
of
1-{[3-(2-bornyl-2-ene)phenyl]diphenyltin}-3,5-di-tert-butyl-
1,2,4-triphosphole (2e).
Replacement of the achiral Ph3Sn group in 1 by SnPh2R*
would be expected to give an ABCX spin-system if the tin
atom were to oscillate only between the two adjacent phos-
phorus atoms in the suprafacial windscreen-wiper mode be-
tween the two diastereomeric minima A and B (Scheme 5).
Exchange of the stereochemical identity of the phosphorus
atoms starting from state A to form identical AЈ is possible
either via state B and planar transition state TiЈ, if the pro-
cess begins with the 1,5-shift, or via Ti and BЈ, if the inver-
sion of the pyramidal phosphorus atom is the initial step.
The molecules must pass through the planar inversion tran-
sition states Ti or TiЈ to generate the observed AB2X spin
All principal isomers of 9 with an 1,2,4-triphosphole
skeleton and a Me3Sn group with Sn–P and Sn–Cring bonds
were considered. Three minima Ϫ 9a, 9b, and 9c Ϫ were
identified for 9 in close energetic proximity. The global
minimum 9a represents the P-chiral 1-stannyl-1,2,4-triphos-
phole case, which has been observed experimentally for all
stannyl-1,2,4-triphospholes in solution and in the solid state
reported so far (Table 3 and Figure 8).
The transition states (structures with one imaginary fre-
quency) are designated Ts(9nǞm) for suprafacial SnMe3-
shift transition states between structures 9n and 9m and as
Scheme 5. Diastereomeric ground states (A and B) at equilibrium
and inversion transition states (Ti) of 1-(triorganylstannyl)-1,2,4-
triphosphole derivatives 2.
Eur. J. Inorg. Chem. 2008, 2225–2237
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2231

M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
Table 3. Calculated total, zero-point vibrational and relative energies of the isomers of model compound 9.
FULL PAPER
Species
B3LYP/LANL2DZ+pol
Nimag
CCSD(T)/LANL2DZ+2pol
Total energy[a] E(rel)[d]
[b]
Total energy[a]
ZPE[c]
E(rel)[d]
9a
–220.09207
–220.08832
–220.08630
–220.08260
–220.07925
–220.07775
–220.08222
0
0
0
1
1
1
1
90.49
90.44
90.62
90.45
90.57
90.61
90.67
0.0
2.3
3.8
5.9
8.1
9.1
6.4
–219.32744
–219.32249
–219.32581
–219.31880
–219.31841
–219.31632
–219.32054
0.0
3.1
1.2
5.4
5.7
7.1
4.5
9b
9c
Ts(9aǞaЈ)
Ts(9aǞb)
Ts(9bǞc)
Ts(9aǞc)
Ts(9bǞbЈ)
Ti(9a)
transition state not located
90.53
90.38
–220.08580
–220.08137
1
1
4.0
6.6
–219.31906
–219.31309
5.3
8.9
Ti(9c)
[a] Total energy in hartrees. [b] Number of imaginary frequencies at the B3LYP/LANL2DZ+pol level. [c] Zero-point vibrational energy
(kcalmol–1) at the B3LYP/LANL2DZ+pol level. [d] Calculated energy (including an unscaled B3LYP/LANL2DZ+pol ZPE correction)
relative to 9a (kcalmol–1).
lated to lie within 4 kcalmol–1. The 1,2-PǞP shift (9aǞ9aЈ)
has an activation energy of 5–6 kcalmol–1. The 1,5-PǞC
shift (9aǞ9b) and 3,4-CǞP shift (9bǞ9c) are calculated
to have less stable transition states, but the 1,4-PǞP shift
(9aǞ9c) is similar in energy to the 1,2-PǞP shift. Direct
inversion at P1 of 9a is easier than that at P4 of 9c and is
close in energy to the easiest SnMe3 shifts.
Figure 8. Calculated structures of (trimethylstannyl)-1,2,4-triphos-
The most apparent feature of Figure 9 is the small range
phole isomers 9a (left), 9b (middle) and 9c (right). The CCSD(T)/
LANL2DZ+2pol relative energies [kcalmol–1] of the three minima
of values for the energy barriers, which span a factor of
only two and include the estimated experimental value of
7.5 kcalmol–1. In agreement with the NMR spectroscopic
findings, the energy required for inversion at P1 or for the
suprafacial 1,2-shift, which both represent epimerisation of
P-chiral 9a, are calculated to be almost identical. A 30%
smaller calculated absolute value may be attributed to the
simplifications of model compound 9, which lacks the
bulky tBu carbon substituents of the derivatives of 2. The
energetic minima 9b and 9c, the transition state for the in-
version of P4 Ti(9c) and the suprafacial shift processes, with
the exception of P1–P2, can be expected to be destabilised
to some extent with respect to 9 by the bulky tert-butyl
groups for the compounds investigated experimentally. The
calculated inversion transition states Ti (Figure 10) and sup-
rafacial SnMe3 group shift Ts (Figure 11) illustrate this
point.
are 9a: 0.0, 9b: 3.1, and 9c: 1.2.
Ti(9n) for inversion transition states for the λ3-phosphorus
atom. The data shown in Table 3 are summarised schemati-
cally in Figure 9.
Figure 9. Shift-barrier calculation results [kcalmol–1] for 9.
With the exception of the simplified substituents, the cal-
culated structural parameters of 9a (Table 2) are all close to
the X-ray data reported for the 1-stannyl-1,2,4-triphos-
pholes 2 in the solid state in this paper and those of 1,[7]
thus suggesting that 9 is an adequate model and that the
level of calculation is appropriate.
All meaningful reaction pathways for migration of the
stannyl group between the minima 9a, 9b and 9c were calcu-
lated. The resulting energy barriers are summarised in Fig-
ure 9.
Figure 10. Calculated ring inversion transition states Ti for 9a (left)
and 9c (right).
The calculations confirm the experimental results. There
The transition states expected to be influenced least by
is considerable variation between the B3LYP and CCSD(T) C substituents are Ti(9a) and that for the suprafacial stan-
results, however, which means that no firm conclusions can nyl group shift Ts(9aǞaЈ). Both of these are identical with
be drawn about the relative ease of the multitude of compet- those postulated on the basis of the NMR spectroscopic
ing rearrangements or even the relative stability of the three properties. Even in the absence of bulky Cring substituents,
competing isomers. However, 9a is found to be the most the highest activation barrier found by the calculations con-
stable structure at both levels and both 9b and 9c are calcu- nects 4-stannyl-1,2,4-triphosphole minimum 9c and its hori-
2232
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 2225–2237

Stannyltriphospholes with Chiral Tin Substituents
performed locally by the microanalytical laboratory at the Depart-
ment für Chemie und Pharmazie of the University of Erlangen-
Nürnberg.
The starting material (3,5-di-tert-butyl-1,2,4-triphospholyl)sodium
(Na5) was prepared by a published route.[7] Diphenyltin dichloride,
(+)-camphor, (–)-cis/trans-myrtanol, 1-bromo-3-chlorobenzene and
solvents were purchased from standard commercial sources. Di-
phenyltin dichloride was recrystallised from dry n-hexane. (1R,2R)-
Bornyl chloride (8a) was prepared according to a published pro-
cedure.[25] The product contains about 10% of the endo isomer iso-
bornyl chloride.[26] (1R)-(–)-Menthyl chloride (8b) was purchased
from Fluka and used without further purification. (–)-cis- and
(–)-trans-Myrtanyl chloride 8c/d were prepared from commercially
available (1S,2R,5S)-(–)-cis- and (1R,2R,5S)-(–)-trans-myrtanol,
respectively, as described in the literature.[27] Activated magnesium
was generated by reduction of water-free MgCl2 with potassium in
thf.[29]
Figure 11. Calculated transition states Ts of suprafacial P–P (top)
and P–C (bottom) stannyl group shifts for 9.
2-(3-Chlorophenyl)-(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-ene
[2-(3-Chlorophenyl)bornyl-2-ene, 8e]: For preparation of the precur-
sor 2-endo-(3-chlorophenyl)borneol, a solution of 1-bromo-3-chlo-
robenzene (16.77 g, 10.3 mL, 87.6 mmol) in 30 mL of dry thf was
added dropwise over 30 min to 50 mL of dry thf containing magne-
sium turnings (2.13 g, 87.6 mmol). The mixture was heated for an
additional two hours at reflux or until the magnesium had dis-
solved. After this time a solution of (+)-camphor (13.34 g,
87.6 mmol) in dry thf (40 mL) was added and the mixture was
heated for an additional 14 h. The reaction mixture was then co-
oled to approximately 0 °C and was hydrolysed carefully with satu-
rated NH4Cl solution (ca. 50 mL). Diethyl ether (50 mL) was
added to form a biphasic system and the layers separated. The
aqueous layer was washed twice more with diethyl ether (20 mL),
then the combined organic phases were washed with saturated
NaHCO3 solution and water and dried with Na2SO4. After filtering
off the drying agent, the solution was evaporated and excess cam-
phor sublimed (10–2 mbar/40–45 °C). Recrystallisation of the solid
residue from petroleum ether or n-hexane yielded the desired prod-
uct as colourless thin needles or a powder (10.2 g, 38.6 mmol,
zontal mirror image 9cЈ through inversion transition state
Ti(9c). As this is a competitive process with higher acti-
vation energy it is not observable by dynamic NMR spec-
troscopy, but 9c may nevertheless contribute to the mobility
of the stannyl groups as a minor component. Variable-tem-
perature NMR spectroscopy of a binuclear W/Cu 1,2,4-tri-
phosphole complex, for example, has shown that the sup-
rafacial exchange of the CuI nucleus from P1 or P2 to P4
has an activation barrier of 10.5 kcalmol–1.[16]
Conclusions
Three different diastereomeric 1-triorganyl-1,2,4-triphos-
pholes 2c,d,e with optically pure stannyl substituents have
been prepared and characterised. Dynamic NMR spec-
troscopy of the compounds has shown, for the first time, a
facile stannyl group shift between the two adjacent P atoms
of the heterocycle (P1 and P2) that includes ring inversion
with a planar transition state Ti. Nicely in line with the
NMR spectroscopic results on diastereomeric derivatives
2c,d,e, DFT and ab initio calculations with the simplified
model compound (trimethylstannyl)-1,2,4-triphosphole (9)
have shown that 1-(trimethylstannyl)-1,2,4-triphosphole
(9a) is the global energetic minimum for 9 and that it un-
dergoes an almost isoenergetic 1,2-shift and ring inversion
as the main epimerisation processes of the two enantiomers
of 9a.
1
44.1%). H NMR (399.65 MHz, CDCl3, 27.2 °C): δ = 0.74 (m, 1
H), 0.84 (s, 3 H, CH3), 0.88 (s, 3 H, CH3), 1.22 (m, 1 H), 1.26 (s,
3 H, CH3), 1.46 (s, 1 H, OH), 1.67 (m, 1 H), 1.72 (s, 1 H), 1.85 (m,
3
1 H), 2.11 (m, 1 H), 2.19 (d, J1H,1H = 10 Hz, 1 H), 7.14 (m, 1 H),
7.18 (m, 1 H), 7.32 (m, 1 H), 7.45 (m, 1 H) ppm. 13C{1H} NMR
(100.40 MHz, CDCl3, 27.2 °C): δ = 10.0 (CH3), 21.89 (CH3), 21.92
(CH3), 26.8, 31.5, 45.9, 46.0, 50.8, 53.9, 83.7 (COH), 125.3, 127.2,
127.5, 129.0, 134.0, 148.5 ppm. MS (FD): m/z (%) 264 (100) [M]+.
C16H21ClO (264.79): calcd. C 72.57, H 7.99; found C 72.85, H 8.19.
Optical rotation (23 °C, c = 0.0824 in thf): [α]546 = –41; [α]578
–36; [α]589 = –34; [α]633 = –30.
=
A solution of 2-endo-(3-chlorophenyl)borneol (5.0 g, 19 mmol) in
pyridine (40 mL) was cooled to –40 °C and thionyl chloride
(1.80 mL, 24.8 mmol) was added dropwise. After an additional
30 min of stirring at –40 °C, the cooling bath was removed and the
reaction mixture warmed to room temperature. After addition of
n-hexane (100 mL) the solid was filtered off and the solvent evapo-
rated. Distillation of the residue at 10–2 mbar and 68–71 °C gave
the desired product 8e as a colourless oil in a yield of 83% (3.9 g,
15.8 mmol). 1H NMR (CDCl3, 269.7 MHz, 19.5 °C): δ = 0.75 (s, 3
Experimental Section
All reactions were carried out in flame-dried glassware under an
oxygen-free atmosphere of dry nitrogen using Schlenk techniques.
Solvents were dried by standard methods and distilled under N2.
All NMR solvents were carefully dried, degassed and stored over
4-Å molecular sieves. NMR spectra were recorded with JEOL
JNM-EX 270, JNM-LA 400 and Bruker Avance DRX 300 spec-
trometers. 1H and 13C NMR chemical shifts are given relative to
residual solvent peaks. 31P NMR chemical shifts are referenced to
external H3PO4 (85%). Mass spectra were recorded with Varian
Mat 212 and JEOL JMS 700 spectrometers. Elemental analysis was
H, CH3), 0.80 (s, 3 H, CH3), 1.02 (s, 3 H, CH3), 1.05 (m, 1 H),
3
1.21 (m, 1 H), 1.60 (m, 1 H), 1.86 (m, 1 H), 2.31 (m, JH3,H4
=
3
3.5 Hz, 1 H(4)], 5.95 (d, JH3,H4 = 3.5 Hz, 1 H(3)], 7.11 (m, 4 Har)
ppm. MS (FD): m/z (%) 246 (100) [M]+.
Eur. J. Inorg. Chem. 2008, 2225–2237
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2233

M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
FULL PAPER
117/119Sn,13
C
39.2 (s, Cal), 38.8 (s, d, J
= 24.7 Hz, Cal), 34.1 (s, Cal),
= 407.6 Hz, Cal), 26.7 (s, Cal),
C
1
117/119Sn,13
28.34 (s, Cal), 28.25 (d, J
26.3 (s, Cal), 23.8 (s, Cal) ppm. MS (FD): m/z (%) 445 (100) [M]+.
C22H27ClSn (445.62): calcd. C 59.30, H 6.11; found C 59.30, H
6.10. Optical rotation (23 °C, c = 0.004 in n-hexane): [α]589 = –1.0;
[α]578 = –1.0; [α]546 = –1.5; [α]436 = –2.75; [α]365 = –5.25.
{(1S,2S)-6,6-Dimethylbicyclo[3.1.1]heptyl-2-methylene}diphenyltin
Chloride {10-[(–)-trans-Myrtanyl]diphenyltin Chloride, 7d}: Yield
4.51 g (10.1 mmol, 36.5%) [starting from (–)-trans-myrtanyl chlo-
ride (4.78 g, 27.7 mmol)]. 1H NMR (300.13 MHz, CDCl3, 26.9 °C):
δ = 0.65 (s, 3 H, CH3), 1.06 (s, 3 H, CH3), 1.28 (m, 2 H), 1.32 (m,
1 H), 1.66 (m, 5 H), 1.78 (m, 1 H), 1.96 (m, 1 H), 2.39 (m, 1 H),
7.34 (m, 6 H, Har), 7.52 (dd, 3JH,H = 7.1, 4JH,H = 2.1, d, 3JH,117/119Sn
= 53.8 Hz, 4 H, Ho) ppm. 13C{1H} NMR (75.47 MHz, CDCl3,
Preparation of the Chiral Modified Tin Compounds 7a–e. General
Procedure: One mol of the chiral organic chloro compound was
added with a syringe directly to a stirred suspension of two mol of
activated magnesium in absolute thf and the mixture heated under
reflux for an additional three hours. After the reaction mixture had
cooled to room temperature it was filtered directly into a rapidly
stirring solution of one mol of diphenyltin dichloride in thf. After
the addition of a small amount of 4-tert-butylcatechol the mixture
was stirred overnight. The solvent was evaporated until a white
precipitate appeared, then an equal volume of n-hexane was added
and the suspension was stirred for an additional hour. After fil-
tration the solvent was evaporated and the residue was eluted on
silica gel (SiO2/5%H2O) with n-hexane/diethyl ether (4:1) as eluent.
The desired products were found in the second fraction and were
identified by the formation of streaks in the solvent. The triorganyl-
tin chlorides were obtained as colourless oils after evaporation of
the solvent. Compounds 7b and 7c were crystallised from n-hexane
at 4 °C as colourless needles.
26.9 °C): δ = 139.57 (Ci), 135.73 (d, 2J
= 47.95 Hz, Co),
117/119Sn,13
C
4
129.98 (d, J
= 13.0 Hz, Cp), 128.90 (d, 3J
=
C
117/119Sn,13
C
117/119Sn,13
117/119Sn,13
57.4 Hz, Cm), 49.28 (s, d, J
C
= 61.0 Hz, Cal), 40.59 (s, Cal),
39.95 (s, Cal), 32.28 (s, Cal), 26.69 (s, Cal), 26.58 (s, Cal), 26.10 (s,
Cal), 24.35 (s, Cal), 22.89 (s, Cal), 19.85 (s, Cal) ppm. MS (FD): m/z
(%) 445 (100) [M]+, 369 (2) [(C6H5)(C10H17)SnCl]+, 137 (2)
[C10H17]+. Optical rotation (23 °C, c = 0.0304 in n-hexane): [α]589
= –0.16; [α]578 = –0.07; [α]546 = 0.07; [α]436 = 1.78; [α]365 = 6.51.
{3-[2-(1R,4S)-1,7,7-Trimethylbicyclo[2.2.1]hept-2-ene]phenyl}-
diphenyltin Chloride {[m-(2-Bornyl-2-ene)phenyl]diphenyltin Chlo-
ride, 7e}: Yield 2.50 g (4.8 mmol, 39.4%) [starting from 2-(3-chlo-
rophenyl)bornyl-2-ene (8e; 3.0 g, 12.2 mmol)]. 1H NMR (CDCl3,
269.7 MHz, 19.8 °C): δ = 0.74 (s, 3 H, CH3), 0.80 (s, 3 H, CH3),
1.02 (s, 3 H, CH3), 1.04 (m, 1 H), 1.20 (m, 1 H), 1.58 (m, 1 H),
{(1R,2R,4R)-1,7,7-Trimethylbicyclo[2.2.1]hept-2-yl}diphenyltin
Chloride [(2-Bornyl)diphenyltin Chloride, 7a]: Obtained as a mixture
of exo and endo isomers. Yield 3.65 g (8.2 mmol, 30.5%). 1H NMR
(300.13 MHz, CD2Cl2, 26.9 °C): δ = 7.48 (m, 10 H, Har), 2.70–0.92
3
3
1.93 (m, 1 H), 2.26 (m, JH,H3 = 3.5 Hz, 1 H4), 5.96 (d, JH,H4
=
[m, 8H (CH, CH2)], 0.84 (s, 3 H, CH3), 0.80 (s, 3 H, CH3), 0.74 (s, 3.5 Hz, 1 H3), 7.40 (m, 14Har) ppm; the numbering scheme is the
3 H, CH3) ppm. MS (FD): m/z (%) 445 (100) [M]+, 308 (2)
same as for 8e. MS (FD): m/z (%) 520 (100) [M]+. Optical rotation:
[SnCl(C6H5)2]+, 137 (10) [C10H17]+.
(23 °C, c = 0.0824 in thf): [α]546 = –33.0; [α]578 = –28.9; [α]589
–22.7; [α]633 = –16.5.
=
2-[(1S,2R,4R)-1-Isopropyl-4-methylcyclohexyl]diphenyltin Chloride
[(–)-Menthyldiphenyltin Chloride, 7b]: Obtained as a 2:1 mixture of
(R)-7b and (S)-7b epimers before workup (9:1 after repeated
Preparation of the Stannyl Triphospholes 2a–e. General Procedure:
A solution containing 1 mol of the chiral modified triorganyltin
recrystallisation). Yield 12.91 g (28.8 mmol, 53.3%).[33] 1H NMR chloride [Ph2SnR*Cl] (7a–e) in toluene was added to a suspension
spectroscopic data identical with those reported in the literature
within the margins of experimental error. 13C{1H} NMR
(75.47 MHz, CDCl3, 25.0 °C): (R)-7b: δ = 141.8/141.5 (s, Ci/CiЈ),
of one mol of (3,5-di-tert-butyl-1,2,4-triphospholyl)sodium (Na5)
in toluene at –50 °C. After stirring and warming to room tempera-
ture overnight, all volatile components were evaporated from the
reaction mixture. The resulting yellow residue was suspended in
135.9 (s, d, 2J
= 45.0 Hz, Co), 129.9 (s, d, 3J
=
117/119Sn,13
C
117/119Sn,13
C
12.9 Hz, Cp), 128.9 (s, d, 4J
= 55.4 Hz, Cm), 46.28 (s, n-hexane and filtered to yield a clear yellow solution, which was
117/119Sn,13
C
117/119Sn,13
117/119Sn,13
C
J
C = 16.5 Hz, CHal), 42.01 (s, CHal), 39.95 (s, d, J
concentrated under vacuum. Products 2a,b,d,e crystallised at
–30 °C as yellow solids, whereas 2c was obtained as a yellow oil
containing an impurity which could not be removed.
117/119Sn,13
= 27.4 Hz, CH2), 35.58 (s, d, J
d, J
C = 27.4 Hz, CHal), 35.32 (s,
117/119Sn,13
C
117/119Sn,13
C
= 84.7 Hz, CHal), 34.93 (s, d, J
= 9.9 Hz,
117/119Sn,13
C
CH2/al), 26.70 (s, d, J
= 89.5 Hz, CH2/al), 22.35 (s, 3 H,
2a: Obtained from 7a (0.42 g, 0.94 mmol) as a 63.5:36.5 mixture of
endo and exo isomers. Yield 0.253 g (0.39 mmol, 42.0%). 1H NMR
(121.49 MHz, CDCl3, 25.1 °C): δ = 0.63/0.61 (s, 3 H, CH3), 0.77/
0.74 (s, 3 H, CH3), 1.13/1.08 (s, 3 H, CH3), 1.51/1.46 [br., 2ϫ18
H, C(CH3)3], 2.58–0.50 (m, 8 H, CH, CH2), 7.67–6.96 (m, 10 H,
Har) ppm. 13C{1H} NMR (100.40 MHz, C6D5CD3, 21.7 °C): δ =
CH3), 21.79 (s, 3 H, CH3), 15.75 (s, 3 H, CH3); (S)-7b: δ = 49.03,
45.56, 38.86, 34.13, 33.98, 33.72, 30.47, 22.27, 21.87, 21.01 ppm.
MS (FD): m/z (%) 447 (100) [M]+, 139 (6) [(C10H19)]+, 860 (20)
[M2 – Cl]+. C22H29ClSn (447.63): calcd. C 59.03, H 6.53; found C
59.32, H 6.61. Optical rotation (22 °C, c = 0.01 in n-hexane): [α]589
= –18.0; [α]578 = –18.6; [α]546 = –21.0; [α]436 = –34.2; [α]365 = –50.9.
1
2
219.18/219.68 [2ϫd pseudo t, JP,C = 35.9/35.3, Σ(1JP,C + JP,C) =
2
{(1S,2R)-6,6-Dimethylbicyclo[3.1.1]heptyl-2-methylene}diphenyltin 65.3/65.2 Hz, Cring), 41.25/41.19 [2ϫd pseudo t, JP,C = 19.8/19.9,
Chloride {10-[(–)-cis-Myrtanyl]diphenyltin Chloride, 7c}: Yield 2.4 g
(5.4 mmol, 34.0%) [starting from (–)-cis-myrtanyl chloride (2.74 g,
3
3
Σ(2JP,C + JP,C) = 5.7/5.8 Hz, C(CH3)], 34.97 [d pseudo t, JP,C
=
10.7, Σ(3JP,C + 4JP,C) = 5.7 Hz, C(CH3)], 141.15/139.60 and 139.93/
15.9 mmol)]; m.p. 99–101 °C. 1H NMR (300.13 MHz, CDCl3, 139.48 (t, JP,C = 3.7/5.7 and 4.1/5.8 Hz, 2ϫ2 Ci), 135.60 (m, Co),
22.0 °C): δ = 0.79 (d, 2JH,H = 9.8 Hz, 1 H), 1.01 (s, 3 H, CH3), 1.06 127.50–124.00* (m, Cp/Cm) ppm. Two sets of signals for aliphatic
(s, 3 H, CH3), 1.45 (m, 1 H), 1.75 (m, 2 H), 1.81/1.83 (s, 2 H), 1.89 carbon atoms: δ = 49.13, 48.73, 48.00, 47.38, 46.70, 46.51, 45.81,
(m, 2 H), 2.03 (m, 1 H), 2.24 (m, 1 H), 2.48 (m, 1 H), 7.36 (m, 6 H, 45.42, 40.24, 40.17, 36.96, 34.11, 26.99, 26.52, 20.35–17.14* ppm
Har), 7.53 (m, 4 H, Har) ppm. 13C{1H} NMR (75.48 MHz, CDCl3, (s, 6ϫCH3); * denotes signals that are partially superimposed by
2
22.0 °C): δ = 139.9 (s, Ci), 136.2 (d, 2J
= 48.0 Hz, Co),
solvent signals. 31P{1H} NMR (161.70 MHz, C6D5CD3, 22.9 °C):
117/119Sn,13
C
130.4 (d, 4J
= 13.1 Hz, Cp), 129.4 (d, 3J
=
endo isomer: δ = 317.13 (t, JP,P = 37.2 + d, J
2
3
117/119Sn,13
C
117/119Sn,13
C
31P,117/119Sn
= 35.6 Hz,
2
117/119Sn,13
C
31P,117/119Sn
= 378.9 Hz, 2 P,
58.1 Hz, Cm), 50.1 (s, d, J
= 63.9 Hz, Cal), 41.4 (s, Cal), 1 P, P3), 160.95 (d, JP,P = 37.2 + d, J
2234
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 2225–2237

Stannyltriphospholes with Chiral Tin Substituents
2
P1+P2) ppm; exo isomer: δ = 315.75 (t, JP,P = 40.4 + d, 3J
31P,117/
2
Σ(JP,C
Σ(2JP,C + JP,C) = 5.8 Hz, C(CH3)], 36.37 [d pseudo t, JP,C = 10.4,
Σ(3JP,C 4JP,C) = 5.8 Hz, C(CH3)], 141.17 (d, J
= 469.3
+ d, 2JP,C = 4.6 Hz, Ci), 137.55 (d, 2J
+
2JP,C) = 64.7 Hz, Cring], 43.30 [d pseudo t, JP,C = 20.8,
2
119Sn
31P,117/119Sn
= 37.2 Hz, 1 P, P3Ј), 162.21 (d, JP,P = 40.4 + d, J
=
3
3
386.7 Hz, 2 P, P1Ј + P2Ј) ppm. MS (FD): m/z (%) 641 (100)
117/119Sn,13
C
+
[M]+, 411 (1) [(C10H17)(C6H5)2Sn]+, 231 (1) [(C2P3 Bu2)2Sn]+, 137
t
117/119Sn,13
= 52.0 Hz, Cm), 130.23 (d, 4J
C = 40.4 Hz, Co), 129.54
(3) [(C10H17)]+. No clear melting behaviour or correct analytical
results could be obtained due to the solvent content of the crystal-
line material.
(d, 3J
= 9.3 Hz,
117/119Sn,13
C
117/119Sn,13
C
Cp), 50.12, 41.64, 40.75, 34.00, 27.48, 27.36, 26.52, 25.45, 23.75,
20.53 ppm. 31P{1H} NMR (121.49 MHz, CD2Cl2, 25.1 °C): δ =
2
3
31P,117/119Sn
318.90 (t, JP,P = 38.8 + d, J
= 51.2 Hz, 1 P, P4), 162.25
P = 358.7 Hz, 2 P, P1 + P2) ppm. MS
2b: Obtained from 7b (1.94 g, 4.3 mmol) as a mixture of two epi-
(d, 3JP,P = 38.8 + d, J
117/119Sn,31
mers. Yield 2.06 g (80.2%). 1H NMR (269.72 MHz, CDCl3,
(FD): m/z (%) 641 (100) [M]+, 410 (22) [(C6H5)2(C10H17)Sn]+, 231
(15) [C2P3tBu2]+, 137 (2) [C10H17]+. M.p. 86–88 °C. C32H45P3Sn
(641.34): calcd. C 59.93, H 7.07; found C 59.34, H 7.54. Optical
25.1 °C): δ = 0.61 (d, JH,H = 6.7 Hz, 3 H, CH3), 0.66 (d, JH,H
6.7 Hz, 3 H, CH3), 0.72 (d, JH,H = 6.6 Hz, 6 H, 2ϫCH3), 0.75 (3
H, CH3), 0.88 (d, JH,H = 6.6 Hz, 3 H, CH3), 0.76–2.33 (m, 2ϫ9
=
rotation (23 °C, c = 0.0024 in n-hexane): [α]589 = 1.25; [α]578
–16.67; [α]546 = 4.17.
=
2
H), 1.39/1.36 (2 s, 2ϫ18 H, C(CH3)3], 3.21 (br. d, JH,117/119
≈
Sn
59 Hz, 2ϫ1 H), 7.27 (m, 6 H, Hm/p), 7.39 (m, 3JH,117/119Sn = 49.9 Hz,
4 H, Ho) ppm. 13C{1H} NMR (67.83 MHz, CDCl3, 25.1 °C): δ =
2e: Synthesised from 7e (2.03 g, 3.9 mmol). Yield 1.71 g (2.4 mmol,
63.4%). 1H NMR (300.13 MHz, CDCl3, 26.9 °C): δ = 0.73 (s, 3 H,
CH3), 0.79 (s, 3 H, CH3), 0.98 (s, 3 H, CH3), 1.03 (m, 1 H), 1.19
(m, 1 H), 1.38 [s, 18 H, C(CH3)3], 1.56 (m, 1 H), 1.85 (m, 1 H),
221.45/220.15 [2ϫd pseudo t, JP,C = 36.0/36.0, Σ(1JP,C + JP,C) =
1
2
2
65.3/63.4 Hz, Cring], 42.44/42.34 [2ϫd pseudo t, JP,C = 20.5/20.5,
Σ(2JP,C + 3JP,C) = 6.2/5.6 Hz, C(CH3)], 36.12/36.11 [2ϫd pseudo t,
3JP,C = 10.6/11.2, Σ(3JP,C
140.53/138.69/138.60 (t, JP,C
+
4JP,C) = 5.0/5.6 Hz, C(CH3)], 140.88/
3
3
2.30 (m, JH,H3 = 3.3 Hz, 1 H, H4), 5.89 (d, JH,H4 = 3.3 Hz, 1 H,
2
H3), 7.31 (m, 14 H, Har) ppm. 13C{1H} NMR (75.47 MHz, CDCl3,
= 4.3/3.7/4.4/7.5 Hz, 2ϫCi/CiЈ),
135.94/135.71/135.66/135.55 (s, 2ϫCo/CoЈ), 127.46 (m, 2ϫCm/CmЈ
26.9 °C): δ = 222.76 [d pseudo t, JP,C = 37.0, Σ(JP,C
+
2JP,C) =
/
64.9 Hz, CRing], 42.96 [d pseudo t, JP,C = 19.6, Σ(2JP,C + JP,C) =
2
3
Cp/CpЈ); 2ϫ10 signals of the epimeric menthyl substituents: 49.28
(s, Cal), 46.93 (s, Cal), 45.71 (s, Cal), 45.05 (s, Cal), 43.75 (s, Cal),
40.64 (s, Cal), 40.12 (s, Cal), 49.32 (s, Cal), 38.46 (s, Cal), 38.19 (s,
Cal), 33.00 (s, Cal), 32.12 (s, Cal), 28.49 (s, Cal), 25.88 (s, Cal), 21.72
(s, Cal), 21.56 (s, Cal), 21.38 (s, Cal), 20.80 (s, Cal), 19.96 (s, Cal),
15.14 (s, Cal) ppm. 31P{1H} NMR (121.49 MHz, CDCl3, 25.1 °C,
5.8 Hz, C(CH3)], 36.37 [d pseudo t, JP,C = 10.9, Σ(3JP,C + JP,C) =
3
4
117/119Sn,13
C
5.8 Hz, C(CH3)], 149.90, 139.30, 139.19, 138.33 (d, J
=
8.7 Hz, Car/olef), 137.18 (d, 2J
= 40.7 Hz, Co), 135.27,
= 13.1 Hz, Cp), 129.11,
117/119Sn,13
117/119Sn,13
C
134.99, 132.68, 129.93 (d, 4J
C
128.74, 128.23, 57.52, 55.32, 52.07, 32.80, 26.08, 20.14, 20.06,
2
13.06 ppm. 31P{1H} NMR (121.49 MHz, CDCl3, 25.1 °C): δ =
2 sets of signals of the AB2 spin system): δ = 319.73 (t, JP,P = 38.8
2
+ d, 3J
= 40.7 Hz, 1 P, P4), 162.16 (d, JP,P = 38.8 + d,
2
3
31P,117/119Sn
31P,117/119Sn
325.05 (t, JP,P = 38.8 + d, J
= 66.6 Hz, 1 P, P4), 159.24
2
(d, 2JP,P = 38.8 + d, J
Sn = 351.4 Hz, 2 P, P1 + P2) ppm. MS
31P,117/119Sn
J
= 377.3 Hz, 2 P, P1 + P2), 315.32 (t, JP,P = 38.8 + d,
31P,117/119
3J
= 37.0 Hz, 1 P, P4Ј), 163.15 (d, JP,P = 38.8 + d, J
2
31P,117/119Sn
31P,117/
(FD): m/z (%) 715 (100) [M]+, 212 (34) [C6H5 – C10H15]+. M.p. 86–
119Sn
= 381.0 Hz, 2 P, P1Ј + P2Ј) ppm. MS (FD): m/z (%) 643 (100)
88 °C. Optical rotation (23 °C, c = 0.0121 in n-hexane): [α]589
–52.3; [α]578 = –55.0; [α]546 = –64.1.
=
[M]+, 139 (5) [C10H19]+. C32H47P3Sn (643.35): calcd. C 59.74, H
7.36; found C 60.66, H 8.28. Optical rotation (24 °C, c = 0.026 in
n-hexane): [α]546 = 17.5; [α]578 = 12.8; [α]589 = 11.6.
Crystal Structure Determinations: Intensity data for 2a and 2b were
collected with a Siemens P4 diffractometer (ω scan technique, 4.0°/
min), whereas those for (R)-7b were collected with a Nicolet R3m/
V diffractometer (ω scan technique, 8.0°/min) and those for 2d and
7c with a Bruker–Nonius KappaCCD diffractometer (φ and ω ro-
2c: Obtained as yellow oil containing about 8.5% of a known
P6C4tBu4H2 cage,[43] which could not be removed, from 7c (0.79 g,
1.77 mmol). Yield 1.02 g (1.59 mmol, 90%). 1H NMR
2
(300.13 MHz, CDCl3, 25.0 °C): δ = 0.66 (d, JH,H = 9.4 Hz, 2 H,
tations). Mo-Kα radiation (graphite monochromator,
λ =
CH2), 0.96 (s, 3 H, CH3), 0.99 (s, 3 H, CH3), 1.41 [s, 18 H,
2ϫC(CH3)3], 1.72 (m, 7 H), 2.20 (m, 2 H), 7.25 (m, 6 H, Har), 7.31
(m, 4 H, Har) ppm. 13C{1H} NMR (75.47 MHz, CDCl3, 25.0 °C):
δ = 222.0 [d pseudo t, JP,C = 36.3, Σ(JP,C + 2JP,C) = 64.7 Hz, Cring],
0.71073 Å) was used for all data collections and data were cor-
rected for Lorentz and polarisation effects. Absorption effects were
taken into account for 2a, 2b and (R)-7b by using a semi-empirical
method based on Psi-scans.[44] A numerical absorption method was
applied[45] for 2d and a semi-empirical method based on multiple
scans (SADABS, Bruker-AXS, 2002)[46] was used for 7c. All struc-
tures were solved by direct methodsand refined by full-matrix least-
squares procedures against F2 with all reflections using SHELXTL-
NT 6.12 (Bruker AXS, 2002).[47] All non-hydrogen atoms were re-
fined anisotropically. The hydrogen atoms were placed in optimised
positions with an isotropic displacement parameter corresponding
to 1.2- or 1.5-times the equivalent isotropic displacement parameter
of their parent carbon atoms. The crystal structure of 2a contains
1.5 molecules of toluene in the asymmetric unit. The half molecule
of toluene is disordered over a crystallographic inversion centre and
was refined using SIMU restraints. Crystal data and experimental
details are listed in Table 4.
2
3
42.83 [d pseudo t, JP,C = 20.3, Σ(2JP,C + JP,C) = 5.8 Hz, C(CH3)],
3
4
36.49 [d pseudo t, JP,C = 10.9, Σ(3JP,C + JP,C) = 5.8 Hz, C(CH3)],
2
140.63/140.45 (s, JP,C
=
5.1 Hz, Ci), 137.03/136.97 (s,
= 11.6 Hz, Cp),
2J
= 40.0 Hz, Co), 129.67 (s, 4J
117/119Sn,13
C
117/119Sn,13
C
129.02 (s, 3J
= 52.4 Hz, Cm), 50.0 (s, J
=
117/119Sn,13
C
117/119Sn,13
C
117/119Sn,13
54.5 Hz), 41.53, 39.68 (s, J
C = 24.0 Hz), 39.17, 34.27, 28.41,
28.20, 26.84, 26.46, 23.84 ppm. 31P{1H} NMR (121.49 MHz,
CDCl3, 25.1 °C): δ = 319.30 (t, JP,P = 37.9 + d, 3J
=
2
31P,117/119Sn
51.2 Hz, 1 P, P3), 162.0 (d, 3JP,P = 37.9 + d, J
P = 356.4 Hz,
117/119Sn,31
2 P, P1 + P2) ppm. MS (FD): m/z (%) 641 (100) [M]+, 410 (1)
[(C6H5)2(C10H17)Sn]+, 231 (2) [C2P3tBu2]+. Optical rotation (23 °C,
c = 0.0026 in n-hexane): [α]589 = –10.0; [α]578 = –10.4; [α]546 = –11.2.
2d: Synthesised from 7d (0.62 g, 1.4 mmol). Yield 0.65 g (1.0 mmol,
72.3%) 1H NMR (300.13 MHz, CD2Cl2, 26.9 °C): δ = 0.52 (s, 3 H, CCDC-660896 (for 2a; originally deposited as 6a), -660897 (for 2b;
CH3), 0.97 (s, 3 H, CH3), 0.99–1.59 (m, 8 H, Hal + CH2), 1.40 [s, deposited as 6b), -660898 (for 2d; deposited as 6d), -660899 (for 7c;
18 H, C(CH3)3], 1.72 (m, 1 H), 1.91 (m, 1 H), 2.18 (m, 1 H), 6.95– deposited as 8c) and -660900 [for (R)-7b; deposited as 8d) contain
4
7.10 (m, 6 H, Har), 7.37 (ddd, 3JH,H = 7.7, 4JH,H = 2.4, JH,H = 1.7
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
+ d, 3J
= 49.9 Hz, 4 H, Har) ppm. 13C{1H} NMR
(75.47 MHz, CD2Cl2, 26.9 °C): δ = 222.60 [d pseudo t, JP,C = 35.8,
117/119Sn,H
Eur. J. Inorg. Chem. 2008, 2225–2237
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2235

M. Hofmann, T. Clark, F. W. Heinemann, U. Zenneck
FULL PAPER
Table 4. Experimental data from X-ray diffraction studies.
2a
2b
2d
7b
7c
Formula
Crystal size [mm]
Crystal system
Space group
a [pm]
b [pm]
c [pm]
α [°]
β [°]
C
42.5H57P3Sn
C32H47P3Sn
0.60ϫ0.55ϫ0.42
triclinic
P1
979.9(1)
1322.8(2)
1374.9(2)
75.56(1)
75.51(1)
78.78(1)
1.6543(4)
2
C32H45P3Sn
0.30ϫ0.28ϫ0.21
monoclinic
P21
1018.32(2)
3312.51(5)
1055.94(2)
90
118.230(2)
90
3.1382(1)
4
C22H29ClSn
0.66ϫ0.22ϫ0.18
monoclinic
P21
1892.6(6)
607.3(2)
1934.3(7)
90
95.39(3)
90
2.213(2)
4
C22H27ClSn
0.18ϫ0.13ϫ0.05
orthorhombic
P212121
999.15(6)
1068.97(4)
1875.4(1)
90
90
90
2.0030(2)
4
0.60ϫ0.50ϫ0.10
triclinic
P1
¯
1105.7(2)
1365.7(2)
1452.7(2)
71.67(1)
88.39(1)
82.10(1)
2.0623(6)
2
γ [°]
V [nm3]
Z
Mr
779.52
0.763
643.35
0.935
641.34
0.986
447.61
1.276
445.62
1.409
µ [mm–1
]
Tmin/Tmax
0.714/0.929
1.255
814
0.621/0.677
1.291
668
0.638/0.823
1.357
1328
0.678/0.795
1.343
912
0.775/0.930
1.478
904
ρ [g cm–3
F(000)
]
T (data coll.) [K]
2Θ range [°]
hkl range
Reflections measured
Reflections unique
Reflections observed
[IՆ4σ(I)]
200 (2)
4.5–54.0
210 (2)
4.7–55.8
100 (2)
7.6–55.8
298 (2)
5.8–50.1
100 (2)
7.0–55.8
–12/12 –11/13 –22/24
23625
4691
4446
–13/9 –16/16 –18/18 –12/7 –17/16 –18/17 –13/13 –42/43 –13/13 –22/22 –7/7 –1/23
14632
8837
7262
10615
10554
9968
56778
14580
13558
7772
7116
3744
Parameters refined
GooF (all data)
R1 (obsd. reflections)
wR2 (all data)
436
669
1.077
0.0279
0.0740
0.015(16)
665
1.041
0.0318
0.0741
0.009(11)
433
0.961
0.0591
0.1630
0.16(10)
219
0.997
0.0166
0.0333
–0.028(11)
1.017
0.0415
0.1142
–
Absolute structure parameter
[10] K. M. Pietrusiewicz, M. Zablocka, Chem. Rev. 1984, 94, 1375;
G. Hoge, J. Am. Chem. Soc. 2004, 126, 9920.
Supporting Information (see also the footnote on the first page of
this article): Details of the theoretical calculations (4 pages, com-
plete set of basis calculation data for ground states 9a–c and transi-
tion states Ti and Ts).
[11] Z. Csók, G. Keglevich, G. Petöcz, L. Kollár, Inorg. Chem. 1999,
38, 831; V. Mouriès, F. Mercier, L. Ricard, F. Mathey, Eur. J.
Org. Chem. 1998, 2683; J. Grundy, B. Donnadieu, F. Mathey,
J. Am. Chem. Soc. 2006, 128, 7716; P. Rosa, L. Ricard, F. Ma-
they, P. Le Floch, Chem. Commun. 1999, 537; M. Westerhau-
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