New chiral tin compounds containing the 2-(4-isopropyl-2-oxazolinyl)-5-phenyl ligand

Article abstract of DOI:10.1016/j.jorganchem.2006.01.023

A series of tri- and tetraorganotin compounds containing the optically active 2-(4-isopropyl-2-oxazolinyl)-5-phenyl ligand and tert-butyl, methyl and/or phenyl groups on the tin has been synthesized. All the novel compounds have been characterized, especi

Full text of DOI:10.1016/j.jorganchem.2006.01.023

Journal of Organometallic Chemistry 691 (2006) 2394–2402
www.elsevier.com/locate/jorganchem
New chiral tin compounds containing the
2-(4-isopropyl-2-oxazolinyl)-5-phenyl ligand
a,
a
a,b
*
´
´
Krzysztof Stalinski , Zofia Urbanczyk-Lipkowska , Piotr Cmoch
,
c
d
Leszek Rupnicki , Andrey Grachev
a
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
b
Pharmaceutical Research Institute, Rydygiera 8, 01-793 Warsaw, Poland
Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland
Nesmeyanow Institute of Organo-Element Compounds, Russian Academy of Sciences, Vavilow 28, 117813 Moscow, Russia
c
d
Received 18 October 2005; received in revised form 30 December 2005; accepted 11 January 2006
Available online 23 February 2006
Abstract
A series of tri- and tetraorganotin compounds containing the optically active 2-(4-isopropyl-2-oxazolinyl)-5-phenyl ligand and tert-
butyl, methyl and/or phenyl groups on the tin has been synthesized. All the novel compounds have been characterized, especially by
means of the multinuclear NMR investigation, the results of which are discussed. The tin halides, as pairs of diastereoisomers in solution,
crystallize in the form of one diastereoisomer. The single-crystal X-ray analysis of tin iodide 10a revealed pseudo-equatorial position of
1
the tert-butyl group opposite to the isopropyl group. In the corresponding diastereomeric tin hydrides values of J(1H–117/119Sn) differ
significantly, suggesting a different pseudo-axial/equatorial position of the hydrogen atom.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: NMR spectroscopy; Sn–N coordination; Tin halides; Tin hydrides
1. Introduction
tional chirality on the tin. It was expected that bulky
tert-butyl group linked to the tin atom might cause a strong
repulsive interaction with the isopropyl group at the stere-
ogenic center of the ligand and lead to one favorable dia-
stereomeric hydride. We now describe the synthesis and
NMR study of tri- and tetraorganotin compounds contain-
ing the optically active 2-(4-isopropyl-2-oxazolinyl)-5-phe-
nyl ligand and tert-butyl, methyl and/or phenyl groups
on the tin.
There have been several reports concerning potentially
intramolecularly coordinated tin compounds, including
hydrides in which the tin atom is coordinated to nitrogen
[1–8] or phosphorus [9] from the ligand. We have recently
described the synthesis and NMR study of tin hydrides
1–3 containing the chiral oxazoline moiety (Fig. 1)
[10,11]. On the basis of the NMR results, especially the
J(15N–117/119Sn) coupling constants it appeared that the
tin atom in the hydrides was indeed intramolecularly coor-
dinated to the nitrogen from the ligand. The hydrides 1–3
have the same substituents (Me, n-Bu, Ph) on the tin and
a stereogenic center in the oxazoline part. The present
study was initiated by our interest in synthesis of intramo-
lecularly Sn–N coordinated hydrides possessing an addi-
2. Experimental
2.1. Materials and methods
The 1H, 13C, 15N, 117Sn NMR spectra were measured in
CDCl3 or C6D6 at 303 K on a Bruker DRX Avance 500
spectrometer equipped with a TBI 500SB H-C/BB-D-05
Z-G probehead, operating at 500.133, 125.773, 50.690
*
Corresponding author. Tel.: +48 22 632 09 04; fax: +48 22 632 66 81.
1
and 186.501 MHz for H, 13C, 15N and 117Sn, respectively.
´
E-mail address: stalinsk@icho.edu.pl (K. Stalinski).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.01.023

K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
2395
Table 1
4
Crystal data and structure refinement for compound 10a
5
6
3
2
Empirical formula
Formula weight
C22H28I1N1O1Sn1
569.05
1'
O
1
3'
Crystal system, space group
Unit cell dimensions
Orthorhombic, P212121
4'
SnH N
R2
5'
˚
a (A)
9.0084(9)
15.660(1)
16.562(2)
2336.4(4)
4, 1.618
6'
1, R = Me
2, R = n-Bu
3, R = Ph
˚
b (A)
˚
c (A)
3
˚
Volume (A )
Z, calculated density (Mg mꢀ3
)
Fig. 1. The Sn–N coordinated tin hydrides 1–3.
Absorption coefficient (mmꢀ1
)
19.136
F(000)
1116
h Range for data collection (ꢁ)
Reflections collected/unique (Rint
Completeness to 2h = 74.23 (%)
Data/restraints/parameters
Goodness-of-fit on F2
3.88–75.85
5190/4616 (0.0663)
98.3
4616/0/236
1.075
1
The assignment of the H and 13C NMR signals of all the
)
compounds studied was made using results of 2D methods
including H–13C gradient selected HSQC (heteronuclear
1
single quantum correlation) and HMBC (heteronuclear
multiple bond correlation). In case of the 15N NMR spec-
tra inverse gated decoupling sequence [possibility of obser-
Final R indices [I > 2r(I)]
R1 = 0.0809, wR2 = 0.1576
ꢀ0.02(5)
Absolute structure parameter
Largest difference in peak and
4.656 and ꢀ3.019
3
˚
vation of J(15N–117/119Sn) couplings] was used otherwise
1
hole (e A )
Wavelength (A)
˚
1.54178
2D H–15N NMR gradient selected HMBC method was
1
Limiting indices
10 6 h 6 11,
applied. The 117Sn NMR spectra were recorded using
inverse gated decoupling sequence. The 1H and 13C
NMR measurements in CDCl3 and C6D6 for all of the
compounds studied were performed using internal tetra-
methylsilane as a standard, whereas for the 15N and
117Sn nuclei external nitromethane and tetramethyltin were
applied as the standards, respectively. IR spectra were mea-
sured on a Perkin–Elmer FT-IR spectrophotometer. EI,
ESI and HRMS spectra were determined on an ADM
604 Inectra GmbH spectrometer. Thin layer chromatogra-
phies were run on silica gel (Merck 60 F254) plates. HPLC
analyses were run using a Merck–Hitachi apparatus and
Kromasil SI 60/7 lm column. All reactions were carried
out under argon atmosphere. 2-(4-Bromo-phenyl)-4-iso-
propyl-4,5-dihydro-oxazole (4) was prepared according
to the published procedures [12]. X-ray diffraction mea-
surements of 10a (crystal of dimensions 0.21 · 0.27 ·
0.54 mm) were performed at 293(2) K at a Nonius BV
MACH3 diffractometer. Structure of 10a was solved with
direct methods using SHELXS97 [13] and refinement with
SHELXL97 [14] programs included into WINGX [15] suite of
programs. H-atoms were included at their calculated posi-
tions and allowed to ride with Biso equal 1.2 of that of the
parent atom. Crystal data of 10a and details of refinement
are shown in Table 1.
ꢀ19 6 k 6 19,
ꢀ20 6 l 6 20
Refinement method
R indices (all data)
Extinction coefficient
Full-matrix least-squares on F2
R1 = 0.2174, wR2 = 0.2703
0.0020(3)
with n-butyl lithium (6.3 mL, 10 mmol, 1.6 M solution in
hexane) was slowly added and the reaction mixture was
stirred for an additional hour and quenched by water.
After addition of diethyl ether the organic layer was
worked up in the usual manner to give a crude product,
which was purified by column, chromatography (hexanes/
ethyl acetate) to give compounds 5–8.
2.2.1.1. (R)-2-[2-(tert-butyl-diphenyl-stannyl)-phenyl]-4-
isopropyl-4,5-dihydro-oxazole (5). Yellowish oil, 95%.
[a]D = ꢀ3.9 (CHCl3, c = 1). IR cmꢀ1 (film): 3061, 2958,
2924, 2872, 2845, 1649, 1466, 1360, 1255, 1083, 1044,
1
727. H NMR (CDCl3) ppm: 8.10–7.30 (14H, m, Harom.),
4.03 (1H, dd, J = 9.8 Hz, J = 8.3 Hz, –OCH2CHN–), 3.89
(1H, t, J = 8.1 Hz, –OCH2CHN–), 3.78 (1H, ddd, J =
9.8 Hz, J = 7.9 Hz, J = 5.5 Hz, –OCH2CHN–), 1.62–1.53
(1H, m, –CHMe2), 1.41 [9H, s, 3J(1H–117/119Sn) = 75.4/
79.0 Hz, –SntBu], 0.75 (3H, d, J = 6.8 Hz, –CHMe2), 0.58
(3H, d, J = 6.8 Hz, –CHMe2). 13C NMR (CDCl3) ppm:
164.5 [J(13C–117/119Sn) = 10.2 Hz, C10], 143.9 [J(13C–
117/119Sn) = 386/404 Hz, Cphenyl], 143.1 [J(13C–117/119Sn) =
2.2. Synthesis
2.2.1. General procedure for the preparation of stannanes
5–8
461/482 Hz,
C
phenyl], 141.8 [J(13C–117/119Sn) = 441/
461 Hz, C1], 138.7 [J(13C–117/119Sn) = 33.9 Hz], 137.5
[J(13C–117/119Sn) = 30.0 Hz], 137.1 [J(13C–117/119Sn) =
To a solution of the corresponding tetraorganostannane
[J(13C–117/119Sn) = 20.8 Hz],
130.6
(Ph3 BuSn, Ph2 BuMeSn or PhtBuMe2Sn, 10 mmol) in
THF was added I2 (2.54 g, 10 mmol) and the reaction mix-
ture was stirred at ambient temperatures for 2 h and then
cooled to ꢀ70 ꢁC. Subsequently, a solution of the o-lithi-
ophenyloxazole prepared by metallation of 2-(4-bromo-
phenyl)-4-isopropyl-4,5-dihydro-oxazole (2.68 g, 10 mmol)
t
t
32.1 Hz],
[J(13C–117/119Sn) = 46.0 Hz], 128.7 [J(13C–117/119Sn) =
32.8 Hz], 128.5 128.0
[J(13C–117/119Sn) = 9.8 Hz],
[J(13C–117/119Sn) = 46.7 Hz], 127.9 [J(13C–117/119Sn) =
41.1 Hz], 127.8 127.7
[J(13C–117/119Sn) = 10.8 Hz],
[J(13C–117/119Sn) = 9.7 Hz], 72.1 (C40), 69.5 (C30), 32.0
134.2

2396
K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
[–SnC(CH3)3], 31.8 (C50), 30.6 [J(13C–117/119Sn) = 493/
516 Hz, –SnC(CH3)3], 18.9 and 17.0 (C60). 15N NMR
(CDCl3) ppm: ꢀ155.4 [J(15N–117/119Sn) = 26.2 Hz]. 117Sn
NMR (CDCl3) ppm: ꢀ114.8. MS (ESI) m/z: 542 (M+ +
Na). Anal. Calcd. for C28H33N1O1Sn1: C, 64.89; H, 6.42;
N, 2.70. Found: C, 64.56; H, 6.47; N, 2.68%.
[–SnC(CH3)3], 27.8 [J(13C–117/119Sn) = 471/488 Hz, –Sn-
C(CH3)3], 19.2 and 16.9 (C60), ꢀ8.1 [J(13C–117/119Sn) =
342/358 Hz, –SnCH3]. 15N NMR (CDCl3) ppm: ꢀ156.0.
117Sn NMR (CDCl3) ppm: ꢀ72.8. MS (EI) m/z: 442
(M+ ꢀ Me, 8), 400 (100), 380 (7), 314 (37), 222 (31). Anal.
Calcd. for C23H31N1O1Sn1: C, 60.56; H, 6.85; N, 3.07.
Found: C, 60.44; H, 6.81; N, 2.96%.
2.2.1.2. (R)-2-[(R)-2-(tert-butyl-phenyl-methyl-stannyl)-
phenyl]-4-isopropyl-4,5-dihydro-oxazole (6). Major dia-
stereoisomer, yellowish oil, 70%. [a]D = +17.1 (CHCl3,
c = 1.1). IR cmꢀ1 (film): 3061, 2957, 2926, 2873, 2844,
1649, 1465, 1359, 1254, 1083, 1044, 726. 1H NMR (CDCl3)
ppm: 8.03 (1H, dd, J = 7.4 Hz, J = 1.7 Hz, Harom.), 7.68
(1H, dd, J = 7.1 Hz, J = 1.6 Hz, Harom.), 7.48–7.24 (7H,
2.2.1.4. (R)-2-[2-(tert-butyl-dimethyl-stannyl)-phenyl]-4-
isopropyl-4,5-dihydro-oxazole (8). Colorless oil, 72%.
[a]D = +18.7 (CHCl3, c = 1). IR cmꢀ1 (film): 3055, 2958,
2922, 2873, 2844, 1649, 1465, 1358, 1253, 1083, 1044,
725. H NMR (CDCl3) ppm: 7.98 (1H, dd, J = 7.6 Hz,
J = 1.4 Hz, Harom.), 7.63 (1H, dd, J = 7.2 Hz, J = 1.4 Hz,
1
m,
Harom.), 4.08 (1H, dd, J = 9.8 Hz, J = 8.3 Hz,
H
arom.), 7.43 (1H, dt, J = 7.3 Hz, J = 1.4 Hz, Harom.),
–OCH2CHN–), 3.95 (1H, t, J = 8.3 Hz, –OCH2CHN–),
3.80 (1H, ddd, J = 9.8 Hz, J = 8.2 Hz, J = 5.9 Hz,
–OCH2CHN–), 1.77–1.70 (1H, m, –CHMe2), 1.27 [9H, s,
3J(1H–117/119Sn) = 70.6/73.9 Hz, –SntBu], 0.87 (3H, d,
J = 6.8 Hz, –CHMe2), 0.74 (3H, d, J = 6.8 Hz, –CHMe2),
7.38 (1H, dt, J = 7.5 Hz, J = 1.5 Hz, Harom.), 4.42–4.36
(1H, m, –OCH2CHN–), 4.18–4.12 (2H, m, –OCH2CHN–),
2.04–1.95 (1H, m, –CHMe2), 1.15 [9H, s, 3J(1H–
117/119Sn) = 69.5/72.7 Hz, –SntBu], 1.04 (3H, d, J = 6.8
Hz, –CHMe2), 0.91 (3H, d, J = 6.8 Hz, –CHMe2), 0.25
[3H, s, 2J(1H–117/119Sn) = 49.0/51.2 Hz, –SnMe], 0.20
[3H, s, 2J(1H–117/119Sn) = 45.2/47.1 Hz, –SnMe]. 13C
NMR (CDCl3) ppm: 164.8 [J(13C–117/119Sn) = 8.9 Hz,
C10], 144.4 [J(13C–117/119Sn) = 400/419 Hz, C1], 137.0
[J(13C–117/119Sn) = 31.7 Hz], 133.7 [J(13C–117/119Sn) =
19.0 Hz, C2], 130.1 [J(13C–117/119Sn) = 42.5 Hz], 128.5
[J(13C–117/119Sn) = 30.2 Hz], 127.9 [J(13C–117/119Sn) =
9.3 Hz], 72.6 (C40), 69.4 (C30), 31.9 (C50), 30.9 [–SnC(CH3)3],
25.1 [J(13C–117/119Sn) = 461/483 Hz, [–SnC(CH3)3], 19.3
and 17.2 (C60), ꢀ7.4 [J(13C–117/119Sn) = 323/338 Hz,
–SnCH3], ꢀ8.2 [J(13C–117/119Sn) = 290/303 Hz, –SnCH3].
15N NMR (CDCl3) ppm: ꢀ155.9 [J(15N–117/119Sn) =
20.1 Hz]. 117Sn NMR (C6D6) ppm: ꢀ28.6. MS (EI) m/z:
380 (M+ ꢀ Me, 19), 338 (100), 322 (14), 308 (19), 252 (44),
222 (32). Anal. Calcd. for C18H29N1O1Sn1: C, 54.86; H,
7.42; N, 3.55. Found: C, 54.69; H, 7.42; N, 3.56%.
2
0.42 [3H, s, J(1H–117/119Sn) = 46.8/48.7 Hz, –SnMe]. 13C
NMR (CDCl3) ppm: 164.5 [J(13C–117/119Sn) = 10.2 Hz,
C10], 144.4 [J(13C–117/119Sn) = 439/460 Hz, Cphenyl], 142.7
[J(13C–117/119Sn) = 419/438 Hz,
C1],
137.6
[J(13C–
117/119Sn) = 33.6 Hz], 136.3 [J(13C–117/119Sn) = 32.0 Hz],
134.1 [J(13C–117/119Sn) = 18.6 Hz], 130.2 [J(13C–117/119Sn)
= 44.5 Hz], 128.7 [J(13C–117/119Sn) = 31.2 Hz], 128.2
[J(13C–117/119Sn) = 9.6 Hz],
127.7
[J(13C–117/119Sn) =
44.9 Hz], 127.4 [J(13C–117/119Sn) = 10.3 Hz], 72.3 (C40),
69.6 (C30), 31.9 (C50), 31.2 [–SnC(CH3)3], 27.6 [J(13C–
117/119Sn) = 460/481 Hz, –SnC(CH3)3], 19.1 and 17.4
(C60), ꢀ8.3 [J(13C–117/119Sn) = 312/326 Hz, –SnCH3]. 15N
NMR (CDCl3) ppm: ꢀ154.6 [J(15N–117/119Sn) = 19.4 Hz].
117Sn NMR (CDCl3) ppm: ꢀ73.3. MS (EI) m/z: 442
(M+ ꢀ Me, 7), 400 (100), 380 (5), 314 (37), 222 (28). Anal.
Calcd. for C23H31N1O1Sn1: C, 60.56; H, 6.85; N, 3.07.
Found: C, 60.53; H, 6.72; N, 2.98%.
2.2.1.3. (R)-2-[(S)-2-(tert-butyl-phenyl-methyl-stannyl)-
phenyl]-4-isopropyl-4,5-dihydro-oxazole (7). Minor dia-
stereoisomer, yellowish oil, 22%. [a]D = +2.6 (CHCl3,
c = 1.1). IR cmꢀ1 (film): 3062, 2958, 2925, 2873, 2841,
1651, 1465, 1360, 1252, 1082, 1044, 727. 1H NMR (CDCl3)
ppm: 8.00–7.27 (9H, m, Harom.), 4.23–4.17 (1H, m,
–OCH2CHN–), 4.04–3.98 (2H, m, –OCH2CHN–), 1.93–
1.86 (1H, m, –CHMe2), 1.23 [9H, s, 3J(1H–117/119Sn) =
72.3/75.6 Hz, –SntBu], 0.93 (3H, d, J = 6.8 Hz, –CHMe2),
0.80 (3H, d, J = 6.8 Hz, –CHMe2), 0.49 [3H, s, 2J(1H–
117/119Sn) = 49.8/52.0 Hz, –SnMe]. 13C NMR (CDCl3) ppm:
164.8 [J(13C–117/119Sn) = 9.8 Hz, C10], 144.8 [J(13C–
117/119Sn) = 374/391 Hz, Cphenyl], 143.2 [J(13C–117/119Sn) =
423/442 Hz, C1], 138.0 [J(13C–117/119Sn) = 33.0 Hz], 136.9
[J(13C–117/119Sn) = 29.2 Hz], 133.9 [J(13C–117/119Sn) =
2.2.2. General procedure for the preparation of triorganotin
bromides and iodides 9–12
A solution of stannanes 5–8 (5.0 mmol) and Br2 or I2
(5.1 mmol) in THF (20 mL) was stirred at ambient
temperatures. The mixture was then evaporated and
the crude product was recrystallized from hexane/CH2Cl2
to give the corresponding halides 9–12 as yellowish
crystals.
2.2.2.1. (R)-2-[(R,S)(S,R)-(2-bromo-tert-butyl-phenylstan-
nyl)-phenyl]-4-isopropyl-4,5-dihydro-oxazole (9). Mixture
of diastereoisomers 4.4/1, yellowish crystals, 97%. IR
cmꢀ1 (KBr): 3065, 2963, 2956, 2924, 2849, 1635, 1461,
1375, 1091, 945. MS (ESI) m/z: 442 (M+ ꢀ Br). HRMS
(ESI): Calcd. for C22H28N1O1Sn1 442.1142. Found
442.1187. Anal. Calcd. for C22H28Br1N1O1Sn1: C, 50.71;
H, 5.42; N, 2.69; Br, 15.33. Found: C, 50.63; H, 5.65; N,
2.53; Br, 15.36%.
20.5 Hz],
130.4
[J(13C–117/119Sn) = 44.4 Hz],
128.6
[J(13C–117/119Sn) = 31.7 Hz], 128.2 [J(13C–117/119Sn) =
9.7 Hz], 127.8 [J(13C–117/119Sn) = 39.8 Hz], 127.5 [J(13C–
117/119Sn) = 9.4 Hz], 72.1 (C40), 69.2 (C30), 31.6 (C50), 31.4

K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
2397
Major diastereoisomer 9a: 1H NMR (CDCl3) ppm:
8.70–7.22 (9H, m, Harom.), 4.52 (1H, t, J = 9.3
Hz, –OCH2CHN–), 4.37 (1H, dd, J = 8.8 Hz, J = 7.2 Hz,
–OCH2CHN–), 4.16 (1H, ddd, J = 9.9 Hz, J = 7.1 Hz,
J = 4.4 Hz, –OCH2CHN–), 1.52–1.47 (1H, m, –CHMe2),
1.49 [9H, s, 3J(1H–117/119Sn) = 102.6/107.3 Hz, –SntBu],
0.69 (3H, d, J = 6.8 Hz, –CHMe2), 0.26 (3H, d, J =
6.8 Hz, –CHMe2). 13C NMR (CDCl3) ppm: 170.0
[J(13C–117/119Sn) = 8.9 Hz, C10], 147.1 [J(13C–117/119Sn) =
638/667 Hz, C1], 144.0 [J(13C–117/119Sn) = 552/578 Hz,
623/652 Hz, C1], 142.4 [J(13C–117/119Sn) = 523/547 Hz,
Cphenyl], 140.5 134.6
[J(13C–117/119Sn) = 36.3 Hz],
[J(13C–117/119Sn) = 41.4 Hz], 132.7 [J(13C–117/119Sn) =
54.7 Hz], 129.7, 129.6 128.3 [J(13C–117/119Sn) = 19.3 Hz],
128.1, 127.0 [J(13C–117/119Sn) = 37.0 Hz], 70.8 (C30), 70.4
[J(13C–117/119Sn) = 10.1 Hz, C40], 37.5 [J(13C–117/119Sn) =
579/606 Hz, –SnC(CH3)3], 31.8 [–SnC(CH3)3], 30.1 (C50),
19.5 and 14.6 (C60). 117Sn NMR (CDCl3) ppm: ꢀ133.2.
15N NMR (CDCl3) ppm: ꢀ179.7 [J(15N–117/119Sn) =
112.6 Hz].
C
phenyl],
[J(13C–117/119Sn) = 43.0 Hz], 132.9 [J(13C–117/119Sn) =
55.7 Hz], 130.2 129.5
[J(13C–117/119Sn) = 29.1 Hz],
[J(13C–117/119Sn) = 13.6 Hz], 128.7 [J(13C–117/119Sn) =
13.5 Hz], 128.3 127.0
[J(13C–117/119Sn) = 56.0 Hz],
139.3
[J(13C–117/119Sn) = 35.5 Hz],
135.2
Minor diastereoisomer 10b: 1H NMR (CDCl3) ppm:
8.79–7.20 (9H, m,
Harom.), 4.54–4.50 (1H, m,
–OCH2CHN–), 4.37 (1H, t, J = 8.7 Hz, –OCH2CHN–),
3.55–3.49 (1H, m, –OCH2CHN–), 2.13–2.06 (1H, m,
3
–CHMe2), 1.50 [9H, s, J(1H–117/119Sn) = 102.1/106.7 Hz,
[J(13C–117/119Sn) = 39.0 Hz], 70.7 (C30), 70.6 [J(13C–
117/119Sn) = 10.3 Hz, C40], 37.9 [J(13C–117/119Sn) = 600/
628 Hz, –SnC(CH3)3], 31.6 [–SnC(CH3)3], 30.4 (C50), 19.6
and 14.9 (C60). 117Sn NMR (CDCl3) ppm: ꢀ149.9.
–SntBu], 0.79 (6H, 2 · d, J = 6.7 Hz, –CHMe2). 13C
NMR (CDCl3) ppm: 170.1 (C10), 147.5, 143.2, 139.7,
134.8 132.6, 130.4, 129.7, 128.4, 128.2, 126.7, 71.1 (C30),
69.3 (C40), 35.7 [–SnC(CH3)3], 31.4 [–SnC(CH3)3], 29.8
(C50), 20.1 and 15.5 (C60). 117Sn NMR (CDCl3) ppm:
ꢀ117.6.
Minor diastereoisomer 9b: 1H NMR (CDCl3) ppm: 8.70–
7.22 (9H, m, Harom.), 4.41–4.37 (1H, m, –OCH2CHN–),
4.32 (1H, t, J = 8.6 Hz, –OCH2CHN–), 3.65–3.59 (1H,
m, –OCH2CHN–), 2.15–2.07 (1H, m, –CHMe2), 1.47
[9H, s, 3J(1H–117/119Sn) = 101.0/105.6 Hz, –SntBu], 0.79
(6H, 2 · d, J = 6.8 Hz, –CHMe2). 13C NMR (CDCl3)
ppm: 170.1 [J(13C–117/119Sn) = 9.9 Hz, C10], 146.0
2.2.2.3. (R)-2-[(R,S)(S,R)-(2-bromo-tert-butyl-methyl-stan-
nyl)-phenyl]-4-isopropyl-4,5-dihydro-oxazole (11). Mixture
of diastereoisomers 10/1, white crystals, m.p. 85–88 ꢁC,
98%. [a]D = + 80.7 (CHCl3, c = 1). IR cmꢀ1 (film): 3057,
2961, 2925, 2874, 2850, 1634, 1466, 1380, 1262, 1095,
1046, 953, 729. MS (EI) m/z: 444 (M+ ꢀ Me, 1), 402
(100), 380 (22), 358 (7), 316 (27), 222 (19). Anal. Calcd.
for C27H26Br1N1O1Sn1: C, 44.49; H, 5.71; N, 3.05; Br,
17.41. Found: C, 44.53; H, 5.72; N, 3.11; Br, 17.56%.
Major diastereoisomer 11a: 1H NMR (CDCl3) ppm:
8.60–8.45 (1H, m, Harom.), 7.83–7.77 (1H, m, Harom.),
7.64 (1H, dt, J = 7.4 Hz, J = 1.3 Hz, Harom.), 7.46 (1H,
dt, J = 7.6 Hz, J = 1.3 Hz, Harom.), 4.59 (1H, dd, J =
10.0 Hz, J = 9.0 Hz, –OCH2CHN–), 4.50 (1H, dd,
J = 8.9 Hz, J = 7.0 Hz, –OCH2CHN–), 4.28 (ddd, J =
10.2 Hz, J = 6.4 Hz, J = 3.2 Hz, –OCH2CHN–), 2.20–
2.10 (1H, m, –CHMe2), 1.31 [9H, s, 3J(1H–
117/119Sn) = 98.0/102.6 Hz, –SntBu], 1.07 (3H, d, J = 6.8
Hz, –CHMe2), 0.87 (3H, d, J = 6.8 Hz, –CHMe2), 0.90
[3H, s, 3J(1H–117/119Sn) = 63.6/66.4 Hz, –SnMe]. 13C
NMR (CDCl3) ppm: 170.1 [J(13C–117/119Sn) = 8.3 Hz,
C10], 145.8 [J(13C–117/119Sn) = 537/562 Hz, C1], 138.4
[J(13C–117/119Sn) = 35.5 Hz], 132.5 [J(13C–117/119Sn) =
[J(13C–117/119Sn) = 648/678 Hz,
117/119Sn) = 575/602 Hz, Cphenyl], 138.5 [J(13C–117/119Sn) =
34.0 Hz], 135.4 132.9
[J(13C–117/119Sn) = 42.8 Hz],
[J(13C–117/119Sn) = 48.2 Hz], 130.4 [J(13C–117/119Sn) =
30.5 Hz], 129.4 128.6
[J(13C–117/119Sn) = 13.7 Hz],
C1],
144.7
[J(13C–
[J(13C–117/119Sn) = 13.5 Hz], 128.3 [J(13C–117/119Sn) =
56.0 Hz], 127.0 [J(13C–117/119Sn) = 40.0 Hz], 70.9 (C30),
70.8 [J(13C–117/119Sn) = 10.3 Hz, C40], 37.6 [J(13C–
117/119Sn) = 565/593 Hz, –SnC(CH3)3], 31.3 [–SnC(CH3)3],
30.5 (C50), 20.2 and 14.8 (C60). 117Sn NMR (CDCl3)
ppm: ꢀ161.4.
2.2.2.2. (R)-2-[(R,S)(S,R)-(2-iodo-tert-butyl-phenylstan-
nyl)-phenyl]-4-isopropyl-4,5-dihydro-oxazole (10). Mix-
ture of diastereoisomers 5.1/1, yellowish crystals, m.p.
198–201 ꢁC, 97%. [a]D = +77.8 (CHCl3, c = 1). IR cmꢀ1
(KBr): 3066, 2965, 2955, 2926, 2850, 1634, 1460, 1376,
t
1091, 944. MS (EI) m/z: 512 (M+ ꢀ Bu, 71), 442 (100),
386 (54), 308 (33), 222 (50). HRMS (EI): Calcd. for
C18H19N1O1120Sn1I1 511.9533. Found: 511.9548. Anal.
Calcd. for C22H28I1N1O1Sn1: C, 46.52; H, 4.97; N, 2.47;
I, 22.34. Found: C, 46.59; H, 4.97; N, 2.48; I, 20.78%.
Major diastereoisomer 10a: 1H NMR (CDCl3) ppm:
8.79–7.20 (9H, m, Harom.), 4.52 (1H, dd, J = 9.5 Hz,
J = 9.2 Hz, –OCH2CHN–), 4.39 (1H, dd, J = 8.8 Hz, J =
7.1 Hz, –OCH2CHN–), 4.17 (1H, ddd, J = 9.9 Hz, J =
7.1 Hz, J = 4.3 Hz, –OCH2CHN–), 1.52 [9H, s, 3J(1H–
117/119Sn) = 104.1/108.9 Hz, –SntBu], 1.47–1.40 (1H, m,
–CHMe2), 0.69 (3H, d, J = 6.7 Hz, –CHMe2), 0.25 (3H,
d, J = 6.7 Hz, –CHMe2). 13C NMR (CDCl3) ppm: 169.6
[J(13C–117/119Sn) = 8.1 Hz, C10], 148.8 [J(13C–117/119Sn) =
55.1 Hz],
129.5
[J(13C–117/119Sn) = 29.0 Hz],
129.1
[J(13C–117/119Sn) = 11.1 Hz], 126.7 [J(13C–117/119Sn) =
29.0 Hz], 70.3 (C30), 69.6 [J(13C–117/119Sn) = 10.7 Hz,
C40], 34.1 [J(13C–117/119Sn) = 573/600 Hz, –SnC(CH3)3],
30.7 [–SnC(CH3)3], 30.0 (C50), 19.4 and 14.6 (C60), 4.3
[J(13C–117/119Sn) = 460/481 Hz, –SnCH3]. 117Sn NMR
(CDCl3) ppm: ꢀ75.7. 15N NMR (CDCl3) ppm: ꢀ181.3
[J(15N–117/119Sn) = 116.3 Hz].
Minor diastereoisomer 11b: 1H NMR (CDCl3) ppm:
8.42–7.43 (4H, m,
Harom.), 4.62–4.57 (1H, m,
–OCH2CHN–), 4.39 (1H, t, J = 8.8 Hz, –OCH2CHN–),
4.08 (1H, ddd, J = 9.6 Hz, J = 4.3 Hz, J = 0.6 Hz,

2398
K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
–OCH2CHN–), 2.20–2.10 (1H, m, –CHMe2), 1.32 [9H, s,
3J(1H–117/119Sn) = 96.2/100.5 Hz, –SntBu], 1.00 (3H, d,
J = 6.8 Hz, –CHMe2), 0.91 [3H, s, 2J(1H–117/119Sn) =
62.4/65.3 Hz, –SnMe], 0.81 (3H, d, J = 6.8 Hz, –CHMe2).
13C NMR (CDCl3) ppm: 170.2 (C10), 145.9 (C1),
138.0, 132.3, 129.5, 129.0, 126.6, 71.3 (C30), 70.1 (C40),
32.9 [–SnC(CH3)3], 30.4 [–SnC(CH3)3], 27.9 (C50), 20.4
and 15.8 (C60), 4.1 (–SnCH3). 117Sn NMR (CDCl3) ppm:
ꢀ60.9.
(EI): Calcd. for C22H28O1N1120Sn1 442.1193. Found:
442.1182.
Major diastereoisomer 13a: 1H NMR (C6D6) ppm: 8.48–
1
7.25 (9H, m, Harom.), 7.15 [1H, s, J(1H–117/119Sn) = 1480/
1549 Hz, –SnH], 4.10–3.85 (3H, m, –OCH2CHN–), 1.68–
1.63 (1H, m, –CHMe2), 1.56 [9H, s, 3J(1H–
117/119Sn) = 77.9/81.1 Hz, –SntBu], 0.72 (3H, d, J = 6.8 Hz,
–CHMe2), 0.57 (3H, d, J = 6.8 Hz, –CHMe2). 13C NMR
(C6D6) ppm: 165.8 [J(13C–117/119Sn) = 9.9 Hz, C10], 143.3
[J(13C–117/119Sn) = 498/521 Hz, Cphenyl], 143.2 [J(13C–
117/119Sn) = 466/487 Hz, C1], 138.6 [J(13C–117/119Sn) =
31.7 Hz], 137.1 [J(13C–117/119Sn) = 35.8 Hz], 133.4 [J(13C–
117/119Sn) = 21.5 Hz], 131.5 [J(13C–117/119Sn) = 48.9 Hz],
128.8, 128.3, 128.2, 127.9, 72.3 (C40), 69.8 (C30), 35.5
(C50), 32.0 [–SnC(CH3)3], 29.2 [J(13C–117/119Sn) = 505/
529 Hz, –SnC(CH3)3], 19.4 and 14.1 (C60). 117Sn NMR
(C6D6) ppm: ꢀ102.0.
2.2.2.4. (R)-2-[(R,S)(S,R)-(2-iodo-tert-butyl-methyl-stan-
nyl)-phenyl]-4-isopropyl-4,5-dihydro-oxazole (12). Mix-
ture of diastereoisomers 21/1, yellowish oil, 98%.
[a]D = +70.1 (CHCl3, c = 1). IR cmꢀ1 (film): 3053, 2962,
2923, 2875, 2849, 1633, 1464, 1381, 1263, 1095, 1046,
1
952, 728. Major diastereoisomer 12a: H NMR (CDCl3)
ppm: 8.60 (1H, d, J = 7.4 Hz, Harom.), 7.80 (1H, d,
J = 7.7 Hz, Harom.), 7.66 (1H, dt, J = 7.4 Hz, J = 1.2 Hz,
Minor diastereoisomer 13b: 1H NMR (C6D6) ppm: 8.48–
1
H
arom.), 7.47 (1H, dt, J = 7.6 Hz, J = 1.1 Hz, Harom.),
7.25 (9H, m, Harom.), 7.35 [1H, s, J(1H–117/119Sn) = 1823/
4.61 (1H, dd, J = 9.8 Hz, J = 9.1 Hz, –OCH2CHN–), 4.54
(1H, dd, J = 8.9 Hz, J = 6.9 Hz, –OCH2CHN–), 4.31
1908 Hz, –SnH], 4.10–3.85 (3H, m, –OCH2CHN–),
1.82–1.75 (1H, m, –CHMe2), 1.52 [9H, s, 3J(1H–
117/119Sn) = 78.6/81.4 Hz, –SntBu], 0.94 (3H, d, J = 6.8
Hz, –CHMe2), 0.88 (3H, d, J = 6.8 Hz, –CHMe2). 13C
NMR (C6D6) ppm: 165.6 [J(13C–117/119Sn) = 7.9 Hz, C10],
144.7 [J(13C–117/119Sn) = 336/351 Hz, Cphenyl], 143.0
(1H,
ddd,
J = 10.3 Hz,
J = 6.9 Hz,
J = 3.8 Hz,
–OCH2CHN–), 2.22–2.13 (1H, m, –CHMe2), 1.33 [9H, s,
3J(1H–117/119Sn) = 99.4/104.1 Hz, –SntBu], 1.10 [3H, s,
2J(1H–117/119Sn) = 61.5/71.1 Hz, –SnMe], 1.01 (3H, d,
J = 6.8 Hz, –CHMe2), 0.81 (3H, d, J = 6.8 Hz, –CHMe2).
13C NMR (CDCl3) ppm: 170.3 (C10), 144.7 [J(13C–
117/119Sn) = 508/530 Hz, C1], 140.0 [J(13C–117/119Sn) =
32.3 Hz], 132.8 [J(13C–117/119Sn) = 53.5 Hz], 129.5, 129.3,
127.0 [J(13C–117/119Sn) = 35.9 Hz], 70.7 (C30), 69.8 (C40),
34.0 [–SnC(CH3)3], 31.1 [–SnC(CH3)3], 30.1 (C50), 19.8
and 14.8 (C60), 8.6 [J(13C–117/119Sn) = 512/532 Hz,
–SnCH3]. 117Sn NMR (CDCl3) ppm: ꢀ58.4 (major diaste-
reoisomer) and ꢀ48.3 (minor diastereoisomer). 15N NMR
(CDCl3) ppm: ꢀ181.9. MS (EI) m/z: 492 (M+ ꢀ Me, 1),
450 (100), 380 (86), 364 (24), 324 (33), 308 (39), 222 (22).
HRMS (EI): Calcd. for C13H17O1N1120Sn1I1 449.9377.
Found: 449.9370. Anal. Calcd. for C17H26I1N1O1Sn1: C,
40.35; H, 5.18; N, 2.77; I, 25.08. Found: C, 40.23; H,
5.18; N, 2.73; I, 22.79%.
[J(13C–117/119Sn) = 467/487 Hz,
C1],
140.1
[J(13C–
117/119Sn) = 37.2 Hz], 138.3 [J(13C–117/119Sn) = 35.6 Hz],
133.1 [J(13C–117/119Sn) = 20.3 Hz], 131.2 [J(13C–117/119Sn) =
49.1 Hz], 128.5, 128.3, 128.1, 127.9, 72.1 (C40), 70.5 (C30),
35.5 (C50), 32.3 [–SnC(CH3)3], 29.0 [J(13C–117/119Sn) =
515/539 Hz, [–SnC(CH3)3], 19.1 and 16.7 (C60). 117Sn
NMR (C6D6) ppm: ꢀ118.9.
2.2.3.2. (R,S)(S,R)-[2-(4-(R)-isopropyl-2-oxazoline)-5-
phenyl]tert-butylmethyltin hydride (14). Mixture of dia-
stereoisomers 6.2/1, yellowish oil, 98%. IR cmꢀ1 (film):
3055, 2960, 2926, 2873, 2845, 1834, 1737, 1643, 1580,
1561, 1480, 1465, 1362, 1087, 1044, 963, 728. MS (EI) m/
z: 380 (M+ ꢀ H, 11), 358 (27), 338 (20), 324 (100), 308
(69), 222 (61). HRMS (EI): Calcd. for C13H18O1N1120Sn1
324.0410. Found: 324.0418.
1
2.2.3. Synthesis of hydrides 13 and 14
Major diastereoisomer 14a: H NMR (C6D6) ppm: 8.15
A solution of NaBH4 (757 mg, 20.0 mmol) in ethanol
(5 mL) was added to a solution of the corresponding tin
halide 9–12 (4.0 mmol) in ethanol (10 mL) and stirred at
0 ꢁC for 5 min. The reaction mixture was treated with
water (1 mL) and the crude product was extracted with
hexane. The extracts were dried over anhydrous MgSO4
and evaporated to afford the corresponding hydride 13 or
14 as colorless oil.
(1H, dd, J = 7.5 Hz, J = 1.1 Hz, Harom.), 8.03 (1H, dd,
J = 7.1 Hz, J = 1.1 Hz, Harom.), 6.35 [1H, s, 1J(1H–
117/119Sn) = 1380/1444 Hz, –SnH], 7.30 (1H, dt, J = 5.7 Hz,
J = 1.4 Hz, Harom.), 7.25 (1H, dt, J = 7.5 Hz, J = 1.4 Hz,
H
arom.), 4.02–3.83 (3H, m, –OCH2CHN–), 1.90–1.84
(1H, m, –CHMe2), 1.41 [9H, s, 3J(1H–117/119Sn) = 75.4/
79.1 Hz, –SntBu], 0.84 (3H, d, J = 6.8 Hz, –CHMe2), 0.76
(3H, d, J = 6.8 Hz, –CHMe2), 0.58 [3H, d, J = 2.0 Hz,
2J(1H–117/119Sn) = 56.4 Hz, –SnMe]. 13C NMR (C6D6)
ppm: 165.9 [J(13C–117/119Sn) = 9.1 Hz, C10], 144.8
2.2.3.1. (R,S)(S,R)-[2-(4-(R)-isopropyl-2-oxazoline)-5-
phenyl]tert-butylphenyltin hydride (13). Mixture of dia-
stereoisomers 1.7/1.0, yellowish oil, 98%. IR cmꢀ1 (film):
3061, 2960, 2923, 2873, 2847, 1836, 1739, 1645, 1580,
1563, 1464, 1362, 1087, 1046, 963. MS (EI) m/z: 442
(M+ ꢀ H, 7), 386 (100), 366 (6), 308 (33), 222 (17). HRMS
[J(13C–117/119Sn) = 447/468 Hz,
C1],
139.8
[J(13C–
117/119Sn) = 36.0 Hz], 133.4 [J(13C–117/119Sn) = 21.4 Hz],
131.2 [J(13C–117/119Sn) = 47.4 Hz], 128.6, 128.2 [J(13C–
117/119Sn) = 7.0 Hz],72.3(C40),69.3(C30),31.8[–SnC(CH3)3],
30.7 (C50), 26.3 [J(13C–117/119Sn) = 489/512 Hz, –SnC(CH3)3],

K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
2399
19.3 and 16.7 (C60), ꢀ7.4 [J(13C–117/119Sn) = 363/380 Hz,
–SnCH3]. 117Sn NMR (C6D6) ppm: ꢀ60.0.
longer (1 h) epimerization was observed, presumable due
to the presence of sodium borohydride or ethoxide anions
formed in the reaction mixture. A similar process has been
reported by Metzger and co-workers [3]. The isolated
organotin hydrides do not racemize and are stable enough
to be used in further radical reactions but they cannot be
stored for a long period of time at room temperature due
to their high reactivity.
Minor diastereoisomer 14b: 1H NMR (C6D6) ppm: 8.17–
1
7.20 (4H, m, Harom.), 6.46 [1H, s, J(1H–117/119Sn) = 1692/
1770 Hz, –SnH], 4.02–3.83 (3H, m, –OCH2CHN–), 1.81–
1.75 (1H, m, –CHMe2), 1.39 [9H, s, 3J(1H–117/119Sn) =
76.4/80.2 Hz, –SntBu], 0.94 (3H, d, J = 6.8 Hz, –CHMe2),
0.87 (3H, d, J = 6.8 Hz, –CHMe2), 0.46 [3H, d, J = 2.0
Hz, 2J(1H–117/119Sn) = 22.2 Hz, –SnMe]. 13C NMR
(C6D6) ppm: 165.5 [J(13C–117/119Sn) = 7.9 Hz, C10], 144.1
3.2. Crystal structure of triorganotin iodide (10a)
[J(13C–117/119Sn) = 443/464 Hz,
117/119Sn) = 34.7 Hz],
133.7
C1],
138.2
[J(13C–
[J(13C–117/119Sn) = 18.8
The molecular structure of tin iodide 10a is shown in
Fig. 2 and selected interatomic parameters are collected
in Table 2. The compound has trigonal bipyramidal coor-
dination geometry at the tin atom, with the N- and I-atoms
located in the apex of the bipyramid and the three carbon
atoms occupying equatorial positions. In the absence of
classic hydrogen bond donors several CH-acceptor interac-
tions are observed in the crystal. Conformation of the com-
plex is stabilized by two intramolecular hydrogen bonds:
Hz], 130.9 [J(13C–117/119Sn) = 29.8 Hz], 128.7 [J(13C–
117/119Sn) = 9.8 Hz], 128.5, 72.7 (C40), 70.1 (C30), 31.7
[–SnC(CH3)3], 30.5 (C50), 26.1 [J(13C–117/119Sn) = 489/
511 Hz, –SnC(CH3)3], 20.5 and 19.2 (C60), ꢀ9.1
[J(13C–117/119Sn) = 287/301 Hz, –SnCH3]. 117Sn NMR
(C6D6) ppm: ꢀ91.0.
3. Results and discussion
˚
C6–H6–I1 [H6–I1 = 2.93(8) A, C6–H6–I1 angle = 133(4)]
˚
3.1. Synthesis of the tin hydrides
and C3–H3–O8 [H3-O8 = 2.57(8) A, C3–H3–O8 angle =
102]. Due to chiral ligand the compound crystallizes in
the non-centrosymmetric space group. Absolute configura-
tion at the C10 stereogenic center is (R), as assigned on the
basis of w-scan based absorption.
Initially, two isomeric tetraorganotin compounds 6 and
7 were expected to be appropriate precursors of triorgano-
tin halides 9–12. The synthesis of these compounds
involved treatment of PhtBuMeSnI with the o-lithiophenyl-
oxazole prepared by metallation of 2-(4-bromo-phenyl)-4-
isopropyl-4,5-dihydro-oxazole with n-butyl lithium in
THF at ꢀ70 ꢁC. They were formed as a 3.2/1.0 mixture
of two diastereoisomers. The mixture could be separated
into pure diastereoisomers using HPLC [16,17]. However,
when stannanes 6 and 7 reacted with bromine or iodine
at ambient temperatures they followed different chemical
pathways. In the case of 6 the usual sequence of reactivity
was reversed, i.e., the methyl group was cleaved preferen-
tially to the aryl group (9 and 10). In the case of 7 tin bro-
mide 11 or iodide 12 was formed according to the general
rule. Such phenomena could be explained by intramolecu-
lar assistance at the tin [10,18]. In view of these results the
reported triorganotin bromides and iodides 9–12 were pre-
pared in a much simpler way via addition of stoichiometric
amount of bromine or iodine to stannanes 5 and 8 (Scheme
1). Tin halides were obtained as mixtures of diastereoiso-
mers: 9 (a/b = 4.4/1.0), 10 (a/b = 5.1/1.0), 11 (a/b = 10/
1), 12 (a/b = 21/1). They could be purified on silica gel to
give satisfactory elemental analyses. The tin halides
appeared to be stable and could be stored at room temper-
ature with exclusion of light for months without decompo-
sition. Crystallization of tin iodide 10a,b results in the
preferential formation of one diastereoisomer 10a. How-
ever, in solution at room temperature the 5.1/1.0 ratio of
10a/10b reestablishes itself. Similar preferential crystalliza-
tion has been reported [6,19]. Reduction of tin halides 9–12
with NaBH4 in ethanol at 0 ꢁC afforded tin hydrides 13 and
14 as mixtures of diastereoisomers: 13 (a/b = 1.7/1.0), 14
(a/b = 6.2/1.0). However, when the reaction time was
3.2.1. Structure in solution of the tetraorganotin compounds
We have recently described that the tin atom in tetraorg-
anotin compounds containing the chiral oxazoline was in
fact pentacoordinated due to the weak Sn–N coordination
[10,11]. Newly synthesized compounds 5–8, which are sub-
strates in two-step reaction leading to hydrides 13 and 14
also share this feature. The 117/119Sn chemical shifts of
tetraorganotins are generally not sensitive to the antici-
pated Sn–N coordination [20]. For compounds 5–8 the
117Sn NMR shifts depend only on a number of phenyl
groups attached to the tin atom: 5 (ꢀ114.8 ppm), 6
(ꢀ73.3 ppm), 7 (ꢀ72.8 ppm), 8 (ꢀ28.6 ppm). Comparison
of the 117Sn NMR data for 5–8 with those of counterparts
t
without the oxazoline substituent (Ph3 BuSn ꢀ108.9 ppm,
Ph2 BuMeSn ꢀ65.0 ppm, PhtBuMe2Sn ꢀ19.1 ppm) indi-
t
cates only small 117Sn shielding increases (5.9–9.5 ppm)
for potentially coordinated stannanes 5–8. More informa-
tive, from the standpoint of the Sn–N interaction parame-
ters, are the 13C and 15N NMR data, especially the
1J(13C–117/119Sn) and the 1J(15N–117/119Sn) couplings.
An increase in coupling constants is ascribed to an increase
of s character in the C1–Sn bond. Comparison of
the J(13C–117/119Sn) for stannanes 5–8 with those
t
from Ph3 BuSn: 139.2 ppm [418/434 Hz], 29.1 ppm
t
[441/462 Hz]; Ph2 BuMeSn: 140.5 ppm [405/424 Hz],
26.7 ppm [432/452 Hz], ꢀ12.2 ppm [299/312 Hz]; PhtBu-
Me2Sn: 141.7 ppm [390/408 Hz], 23.9 ppm [423/443 Hz],
ꢀ12.1 ppm [290/304 Hz] shows either increase or decrease
of the 1J(13C–117/119Sn) couplings at carbons directly
bounded to the tin for 5–8 (Table 3). As previously proved

2400
K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
MgMeCl, THF, 0 oC
30 min, 98 %
I2, THF, rt
2 h, 97 %
I2, THF, rt
2 h, 94 %
t
t
PhMetBuSnI
Ph3 BuSn
Ph2 BuSnI
Ph2MetBuSn
4, n-BuLi, THF
4, n-BuLi, THF
-70 oC, 92 %
-70 oC, 95 %
MgMeCl
O
THF, 0 oC
30 min, 95 %
R2SnH N
O
O
1, R = Me
t
2, R = n-Bu
3, R = Ph
Ph2 BuSn
N
Me Sn
tBu
I2, THF
rt, 1 h
85 %
N
t
PhMe2 BuSn
Ph
Br2 or I2, THF, rt
1 h, 97 %
5
6, 70 %
+
O
I2, THF, rt
2 h, 85 %
Br
N
O
O
4
Ph
tBu Me
Sn
N
Sn
I
N
N
t
Me2 BuSnI
tBu Ph
+
7, 22 %
9a (X = Br)
10a (X = I)
NaBH4/EtOH
4, n-BuLi, THF
-70 oC, 72 %
0 oC, 5 min
98 %
I2, THF, rt
1 h, 98 %
O
9b (X = Br)
10b (X = I)
Sn
I
O
tBu
Ph
Br2 or I2
THF, rt
1 h, 97 %
O
N
O
PhtBuSnH N
t
Sn
X
Me2 BuSn
N
13
tBu
Me
NaBH4/EtOH
0 oC, 5 min
98 %
8
O
+
11a (X = Br)
12a (X = I)
t
SnH N
Me Bu
14
O
11b (X = Br)
12b (X = I)
Sn
X
N
tBu
Me
Scheme 1. The preparation of tin compounds 5–14.
Table 2
Selected bond lengths and angles for 10a
˚
Bond lengths (A)
Angles (ꢁ)
Sn–1–C15 2.11(2) C1–Sn1–C15 120.1(7) C21–Sn1–N11 95.1(6)
Sn1–C1
Sn1–C21
2.19(2) C15–Sn1–C21 118.7(9) C15–Sn1–I1
2.21(2) C1–Sn1–C21 118.5(9) C1–Sn1–I1
92.6(6)
94.3(7)
94.3(7)
167.1(4)
Sn1–N11 2.44(2) C15–Sn1–N11 87.1(7) C21–Sn1–I1
Sn1–I1 2.867(2) C1–Sn1–N11 74.9(8) N11–Sn1–I1
by NOE differential and NOESY experiments the tert-
butyl group in stannanes 5–8 occupies a pseudo-equatorial
position opposite to the isopropyl one due to steric reasons.
Therefore, it is reasonably safe to assume that the consid-
1
erably large differences between the J(13C–117/119Sn) cou-
plings observed at the phenyl/methyl carbons directly
bounded to the tin of 5–8 are due to pseudo-axial/equato-
rial positions of two remaining groups (Ph or Me) caused
by the Sn–N interaction. An additional proof supporting
the Sn–N coordination was obtained from long accumu-
Fig. 2. Molecular structure and atomic numbering scheme for tin iodide
10a.

K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
2401
Table 3
The selected 1J(117/119Sn–13C) values of stannanes 5–9, 13, 14
Stannane
1J(117/119Sn–13C)
C1 tert-butyl
C1 ligand
C1 phenyl
C1 methyl
5
6
30.6 (493/516)
27.6 (460/481)
27.8 (471/488)
25.1 (461/483)
37.9 (600/628)
37.6 (565/593)
29.2 (505/529)
29.0 (515/539)
26.3 (489/512)
26.1 (489/511)
141.8 (441/461)
142.7 (419/438)
143.2 (423/442)
144.4 (400/419)
147.1 (638/667)
146.0 (648/678)
143.2 (466/487)
143.0 (467/487)
144.8 (447/468)
144.1 (443/464)
143.9 (386/404), 143.1 (461/482)
–
144.4 (439/460)
144.8 (374/391)
–
144.0 (552/578)
144.7 (575/602)
143.3 (498/521)
144.7 (336/351)
–
ꢀ8.3 (312/326)
7
ꢀ8.1 (342/358)
8
ꢀ7.4 (323/338), ꢀ8.2 (290/303)
9a
9b
13a
13b
14a
14b
–
–
–
–
ꢀ7.4 (363/380)
–
ꢀ9.1 (287/301)
lated 15N NMR spectra taken for 5, 6 and 8 in which
appearance of the 1J(15N–117/119Sn) couplings of 26.2,
19.4 and 20.1 Hz was observed, respectively.
3.2.3. Structure in solution of the triorganotin hydrides
The tin hydrides 13 and 14 were obtained as mixtures of
diastereoisomers: 13 (a/b = 1.7/1.0), 14 (a/b = 6.2/1). In
the 117Sn NMR spectra of hydrides 13 and 14 two separate
signals for each compound are observed in a typical range
for tin hydrides. The 117Sn NMR chemical shifts for both
hydrides depend on the substituents at the tin and are as
follows: 13 (a/b = ꢀ102.0/ꢀ118.9 ppm), 14 (a/b = ꢀ60.0/
ꢀ91.0 ppm). They are quite close to those of counterparts
3.2.2. Structure in solution of the triorganotin halides
Due to the preferential cleavage of pseudo-axial groups
over pseudo-equatorial ones, the triorganotin halides 9–12
can be obtained in a nearly quantitative yield from the
reaction of 5 and 8 with bromine or iodide. It was expected
that the bulky tert-butyl group linked to the tin atom might
cause a strong repulsive interaction with the isopropyl
group at the stereogenic center of the ligand and lead to
one favorable diastereomeric halide. Indeed, the halides
were obtained with good to high diastereoselectivity: 9
(a/b = 4.4/1.0, 63% de), 10 (a/b = 5.1/1.0, 67% de), 11
(a/b = 10/1, 82% de), 12 (a/b = 21/1, 91% de). It is rather
difficult to determine the structure of second minor isomer
but the dominant form is that with halogen at axial posi-
tion of the trigonal bipyramid, what in the case of 10a
was proved by the X-ray diffraction measurements. The
1H and 117Sn NMR spectra of solutions of tin halides 9–
12 showed no change in the diastereomeric ratios even after
10 days at rt. However, on cooling the 1H NMR spectra of
the halides revealed increases of the major diastereoisomers
at the expense of the minor ones. It reflects the dynamic
equilibrium of the tin halides in solution [21,22]. Particu-
t
without the oxazoline moiety: Ph2 BuSnH ꢀ118.6 ppm,
PhtBuMeSnH ꢀ86.9 ppm. Based only on this comparison
it is not possible to correlate these values with geometry
1
at the tin. More informative are the H NOE differential
experiments taken for 13a/b–14a/b at low temperatures
in toluene–d8. Analysis of the NOEs observed for the
hydrides clearly proves that in solution two diastereoiso-
meric hydrides with hydrogen in pseudo-axial/equatorial
positions are present. This conclusion is strongly sup-
1
ported by the J(1H–117/119Sn) couplings for triorganotin
hydrides 13 and 14. The corresponding values differ signif-
icantly at 30 ꢁC (13a 1480/1549 Hz, 13b 1823/1908 Hz, 14a
1380/1444 Hz, 14b 1692/1770 Hz), suggesting a different
position of the hydrogen atom. Similar but smaller differ-
1
ences in the J(1H–117/119Sn) couplings of the investigated
hydrides have been reported by Metzger and co-workers
[3] and Dakternieks et al. [6]. Moreover, the 1J(1H–117/
119Sn) couplings seem to be temperature dependent. The
1H NMR measurements of 13a/b in toluene–d8 at different
1
larly interesting are the J(13C–117/119Sn) couplings of 9,
which are different for both forms a and b (ca. 20–
30 Hz). This could suggest different chemical environments
of the substituents at the tin. Unfortunately, in the case of
minor diastereoisomers of 10b–12b it was not possible to
1
temperatures show noticeable differences in the J(1H–117/
119Sn) couplings, although the diastereomeric ratios of
13a/b does not change with temperature [23]. At low
(ꢀ60 and ꢀ20 ꢁC) and high (+80 ꢁC) temperatures they
are as follows: 13a (1384/1448 Hz, 1426/1493 Hz), 13b
(1887/1974 Hz, 1850/1936 Hz) and 13a (1545/1617 Hz),
13b (1792/1876 Hz), respectively. The same phenomenon
was observed for hydride 14a/b: ꢀ60 ꢁC 14a (1284/
1344 Hz), 14b (1727/1806 Hz) and ꢀ20 ꢁC 14a (1360/
1423 Hz), 14b (1707/1785 Hz). Analysis of the values of
1
detect the J(13C–117/119Sn) due to broad carbon signals
(half-heights ca. 15 Hz). Comparison of the 117Sn NMR
chemical shifts of 9 (a/b = ꢀ149.9/ꢀ164.4 ppm), 10 (a/
b = ꢀ133.2/ꢀ117.6 ppm), 11 (a/b = ꢀ75.7/ꢀ60.9 ppm)
and 12 (a/b = ꢀ 58.4/ꢀ48.3 ppm,) with those of counter-
t
parts (Ph2 BuSnI: ꢀ36.7 ppm, PhtBuMeSnI: ꢀ20.3 ppm)
shows remarkable 117Sn shielding increases for coordinated
tin halides 9–12. Additionally, in the 15N NMR spectra of
10a and 11a we observed the 1J(15N–117/119Sn) couplings as
small satellite line (10a 112.6 Hz, 11a 116.3 Hz). This con-
firms the existence of the Sn–N interaction in these mole-
cules in solution.
1
the J(13C–117/119Sn) observed at C1 (phenyl or methyl)
resonances of the pseudo-axial substituents shows that they
are smaller than the pseudo-equatorial substituents in
hydrides 13a/b and 14a/b, respectively (Table 3). On the
basis of these results we propose distorted tetrahedral

2402
K. Stalin´ski et al. / Journal of Organometallic Chemistry 691 (2006) 2394–2402
Acknowledgments
O
O
O
Financial support by the Institute of Organic Chemistry,
Polish Academy of Sciences and the Scientific Research
(Grant No. 4 TO9A 063 25) is gratefully acknowledged.
Sn
Sn
H
N
N
Ph
tBu
N
tBu Ph
H
13b
13a
References
[1] H. Schumann, B.C. Wassermann, F.E. Hahn, Organometallics 11
(1992) 2803.
[2] E. Vedejs, S.M. Duncan, A.R. Haight, J. Org. Chem. 58 (1993) 3046.
[3] K. Schwarzkopf, J.O. Metzger, W. Saak, S. Pohl, Chem. Ber./Recueil
130 (1997) 1539.
O
Sn
Sn
H
Me
tBu
N
tBu Me
14a
H
14b
[4] D. Dakternieks, K. Dunn, V.T. Perchyonok, C.H. Schiesser, Chem.
Commun. (1999) 1665.
Scheme 2. Axial versus equatorial position of the hydrogen atom in
[5] D. Dakternieks, K. Dunn, C.H. Schiesser, E.R.T. Tiekink, J.
Organomet. Chem. 605 (2000) 209.
hydrides 13–14.
[6] D. Dakternieks, K. Dunn, C.H. Schiesser, E.R.T. Tiekink, J. Chem.
Soc., Dalton Trans. (2000) 3693.
[7] D. Dakternieks, C.H. Schiesser, Aust. J. Chem. 54 (2001) 89.
[8] D. Dakternieks, V.T. Perchyonok, C.H. Schiesser, Tetrahedron:
Asymm. 14 (2003) 3057.
coordination geometry at tin and the pseudo-axial/equato-
rial position of hydrogen atom for the investigated diaste-
reomeric hydrides (Scheme 2).
[9] G. Muller, J. Brand, Z. Anorg. Allg. Chem. 631 (2005) 2820.
´
´
[10] P. Cmoch, Z. Urbanczyk-Lipkowska, A. Petrosyan, A. Ste˛pien, K.
In conclusion, the new hydrides can be easily prepared
from the corresponding tetraorganotin compounds. In
the diastereomeric triorganotin hydride values of the
1J(1H–117/119Sn) differ significantly, suggesting a different
pseudo-axial/equatorial position of the hydrogen atom.
The isolated hydrides do not racemize and are stable
enough to be used in radical and nucleophilic reductions.
Further investigations concerning application of the
hydrides are in progress.
´
Stalinski, J. Mol. Struct. 733 (2005) 29.
´
´
[11] L. Rupnicki, Z. Urbanczyk-Lipkowska, A. Ste˛pien, P. Cmoch, Z.
´
Pianowski, K. Stalinski, J. Organomet. Chem. 690 (2005) 3690.
[12] M. Peer, J.C. de Jong, M. Kiefer, T. Langer, H. Rieck, H. Schell, P.
Sennhenn, J. Sprinz, H. Steinhagen, B. Wiese, G. Helmchen,
Tetrahedron 52 (1996) 7547.
[13] G.M. Sheldrick, Acta Crystallogr. A46 (1990) 467.
[14] G.M. Sheldrick, SHELXL97, Program for Crystal Structure Refine-
ment, University of Go¨ttingen, Germany, 1997.
[15] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[16] I.V. Eynde, M. Gielen, J. Organomet. Chem. 198 (1980) C55.
[17] I.V. Eynde, M. Gielen, G. Stuhler, A. Mannschreck, Polyhedron 1
¨
(1982) 1.
4. Supplementary material
[18] B. Jousseaume, P.J. Villeneuve, J. Chem. Soc., Chem. Commun.
(1987) 513.
[19] G. van Koten, J.T.B.H. Jastrzebski, J.G. Noltes, J. Am. Chem. Soc.
100 (1978) 5021.
[20] J.T.B.H. Jastrzebski, J. Boersma, P.M. Esch, G. Van Koten,
Organometallics 10 (1991) 930.
[21] M. Gielen, Top. Curr. Chem. 104 (1983) 57.
[22] M. Gielen, M. Biesemans, R. Willem, Appl. Organomet. Chem. 19
(2005) 440.
Crystallographic data (excluding structure factors) for
the structure 5 in this paper has been deposited with the
Cambridge Crystallographic Data Center as Supplemen-
tary Publication No. CCDC 285182. Copies of the data
can be obtained free of charge, on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 0
1223 336033 or e-mail: deposit@ccdc.cam.ac.uk].
[23] M. Gielen, Y. Tondeur, J. Organomet. Chem. 169 (1979) 265.