Diarylstannylene reactions with some aryl azides: Formation of different ring systems

Article abstract of DOI:10.1016/S0022-328X(99)00010-8

The reactions of the diarylstannylene Ar₂Sn: (1), Ar = 2,4,6-tBu₃C₆H₂ with the azides RN₃, R = 2,6-iPr₂C₆H₃ (3) or 2,4,6-Me₃C₆H₂ (4), proceed via the stannanimines, which rearrange by intramolecular addition of a C-H bond of one of the ortho-tert-butyl groups across the Sn=N bond to furnish the stannaindan derivatives 7 and 8. Treatment of 1 with excess 3,5-bis(trifluoromethyl)phenyl azide (9) affords the tetraazastannoline derivative 10 by a [3 + 2] cycloaddition reaction of 9 to the stannanimine intermediate The structures of 7 and 10 were determined by X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(99)00010-8

Journal of Organometallic Chemistry 579 (1999) 280–284
Diarylstannylene reactions with some aryl azides: formation of
different ring systemsꢀ
Ulrike Fooken, Wolfgang Saak, Manfred Weidenbruch *
Fachbereich Chemie der Uni6ersita¨t Oldenburg, Carl-6on-Ossietzky-Straße 9–11, D-26111 Oldenburg, Germany
Received 26 November 1998
Abstract
The reactions of the diarylstannylene Ar2Sn: (1), Ar=2,4,6-tBu3C6H2 with the azides RN3, R=2,6-iPr2C6H3 (3) or
2,4,6-Me3C6H2 (4), proceed via the stannanimines, which rearrange by intramolecular addition of a C–H bond of one of the
ortho-tert-butyl groups across the SnꢀN bond to furnish the stannaindan derivatives 7 and 8. Treatment of 1 with excess
3,5-bis(trifluoromethyl)phenyl azide (9) affords the tetraazastannoline derivative 10 by a [3+2] cycloaddition reaction of 9 to the
stannanimine intermediate The structures of 7 and 10 were determined by X-ray crystallography. © 1999 Elsevier Science S.A. All
rights reserved.
Keywords: Tin; Stannylene; Stannaindan; Tetraazastannoline
2. Results and discussion
1. Introduction
Some of the most interesting reactions of stannylenes
are those with azides to form mainly the thermally
labile stannanimines [8,9]. Recently Meller and co-
workers isolated and completely characterized the first
and as yet only stannanimine that is stable at −30°C
from the reaction of [(Me3Si)2N]2Sn: with the azide
RN3 (R=2,6-iPr2C6H3) [10]. Thus, it seemed worth-
while to make use of the steric overcrowding in the
diarylstannylene 1 in an attempt to generate more
stable stannanimines.
Structurally characterized diarystannylenes without
donor-stabilization are still very rare [2]. One such
example is compound 1, which is stable in the solid
state but undergoes rearrangement to afford the alky-
larylstannylene 2 in solution (Scheme 1, [3]). Accord-
ingly, all reactions of 1 with the heavier chalcogens of
transition metal substrates yielded products arising ex-
clusively from the rearranged stannylene 2 [4–6].
An exception to this behaviour pattern is the reaction
of 1 with carbon disulfide which proceeds without
isomerization by insertion of one or two molecules of
CS2 in the SnꢁC bonds to furnish tri- or tetracoordi-
nated stannylenes [7]. We now report on reactions of 1
with some aryl azides—also proceeding without iso-
merization—to furnish initially stannanimines which
then undergo further intra- or intermolecular reactions
to provide various cyclic products.
Reaction of the diarylstannylene 1 with the azide 3
does indeed furnish a colourless crystalline product in
44% yield with analytical data suggestive of a stannan-
imine. However, the spectral data are not compatible
1
with such a structure; for example, the H-NMR spec-
trum reveals signals for an NH group and an AB spin
system for a ring CH2 group thus indicating that a
rearrangement of the primarily formed stannanimine 5
has occurred (Scheme 2).
An X-ray crystallographic analysis (Fig. 1, Table 1)
shows that the stannaindan derivative 7 has been
ꢀ See Ref. [1].
* Corresponding author. Tel.: +49-441-7983655; fax: +49-441-
7983352.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00010-8

U. Fooken et al. / Journal of Organometallic Chemistry 579 (1999) 280–284
281
sufficient ability to adequately protect the electron sex-
tet molecule from a rearrangement.
formed through intramolecular addition of a CꢁH bond
of one of the ortho-tert-butyl groups to the SnꢀN bond
of 5. Meller and co-workers [10] had observed a similar
subsequent reaction on thermal treatment of their stan-
nanimine, albeit with the difference that the CꢁH addi-
tion to the double bond proceeded from the
N-substituent and not, as in our case, from the one of
the Sn-aryl subsitutents.
The reaction of 1 with mesityl azide (4) takes a
similar course to afford the stannaindan 8 by way of
the stannanimine 6. The structure of 8 was confirmed
by a complete NMR spectral analysis. An interesting
result of both reactions is that the formation of 7 or 8
via the intermediates 5 or 6 takes place without the
almost always observed aryl/alkyl isomerization of the
stannylene 1. It would seem that, like the CꢁS bonds in
CS2, the NꢁN bonds of the employed azides have a
The reaction of 1 with the aryl azide 9, however,
follows a different course. Although no unambiguously
identified products have as yet been isolated from the
equimolar reaction of the two components, use of an
excess of 9 does lead to the formation of the tetraaza-
stannoline 10 (Scheme 3, Fig. 2 and Table 2). Com-
pound 10 is presumably the result of a [3+2] cycload-
dition of 9 to the stannanimine intermediate. Similar
tetrazastannolines have been reported previously but a
search of the Cambridge Crystallographic Data File
showed that no structure determination has yet been
reported.
The X-ray crystallographic analysis of 10 revealed
major similarities with the structures of the correspond-
ing tetraazasilolines [11,12] and tetraazagermolines
[13,14]. With an angular sum of 539.7° the SnN4 ring is
practically planar. In comparison with the analogous
silicon and germanium compounds [11–14,17,18], the
markedly longer SnꢁN bond lengths in 10 result in a
much smaller NꢁSnꢁN bond angle of 72.9(1)°. To
accommodate this very small angle in a five-membered
ring the angles at N(1) and N(2) are appreciably
widened. This very acute angle together with the lower
SnꢁC bond energy as compared to SiꢁC and GeꢁC
bonds are presumably responsible for the low thermal
stability of 10.
Scheme 1.
3. Experimental
3.1. General procedure
All reactions were carried out in oven-dried glass-
ware under an atmosphere of dry argon.
The H-, 13C-, and 119Sn-NMR spectra were obtained
on a Bruker AM 300 or Bruker AMX 500 spectrometer
1
Scheme 2.
using C6D6 or toluene-d8 as solvents. The assignments
1
of the H- and 13C-signals were confirmed by DEPT,
COSY, and COLOC spectra. Mass spectra were
recorded on a Varian-MAT 212 instrument. UV/vis
spectra were taken on a ConSpec spectrometer with
fiber optics. Elemental analyses were performed by
Analytische Laboratorien, D-51779 Lindlar, Germany.
3.2. 2,6-Diisopropylphenyl-[5,7-di-tert-butyl-3,3-
dimethyl-1-(2,4,6-tri-tert-butylphenyl)-1-
stannaindan-1-yl]amine (7)
At −30°C, the azide 3 (0.5 g, 2.5 mmol) was added
to a solution of 1 (1.5 g, 2.5 mmol) in toluene (50 ml)
with stirring. The mixture was allowed to warm to r.t.
over a period of 2 h and concentrated to a volume of 20
ml. Cooling of the solution at 4°C afforded a yellow
Fig. 1. Molecular structure of 7 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability.

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U. Fooken et al. / Journal of Organometallic Chemistry 579 (1999) 280–284
3
Table 1
MHz, 263 K, toluene-d8): l 0.43 (d, 3 H, J=6.3 Hz),
Selected bond lengths (pm) and angles (°) for 7
3
0.87 (s, 9 H), 1.13 (m, 6 H), 1.23 (d, 3 H, J=6.3 Hz),
1.26 (s, 18 H), 1.36 (s, 9 H), 1.53 (s, 3 H), 1.62 (s, 9 H),
1.80 (d, 1 H, J=13.2 Hz), 1.81 (s, 3 H), 1.83 (d, 1 H),
Bond lengths (pm)
Sn−C(31)
Sn−C(20)
2
218.8(4) Sn−C(13)
213.7(4) Sn−N
219.4(2)
208.4(3)
2.24 (m, 1 H), 2.45 (m, 1 H), 2.86 (s, 1 H, NH), 6.73
3
(dd, 1 H), 6.80 (d, 1 H, J=7.3 Hz), 6.97 (d, 1 H,
Bond angles (°)
N−Sn−C(31)
N−Sn−C(13)
Sn−C(13)−C(14)
3J=7.3 Hz), 7.33 (s, 1 H), 7.44 (s, 1 H), 7.59 (s, 1 H),
7.66 (s, 1 H) ppm. 13C-NMR (298 K, toluene-d8): l
23.46 (Cp), 31.39 (Cp), 31.52 (Cp), 32.21 (Cp), 32.98
(CH2), 33.74 (Cp), 34.35 (Cp), 34.58 (Cq), 34.83 (Cq),
35.78 (Cp), 36.57 (Cq), 37.48 (Cp), 39.66 (Cq), 40.38
(Cq), 41.39 (Cq), 119.34 (Ct), 121.59 (Ct), 121.82 (Ct),
123.18 (Ct), 123.31 (Ct), 123.94 (Ct), 135.82 (Cq), 137,81
(Cq), 145.90 (Cq), 150.32 (Cq), 151.33 (Cq), 154.21 (Cq),
158.16 (Cq), 158.23 (Cq), 158.81 (Cq) ppm. Cp, Ct, and
Cq refer to primary, tertiary, and quaternary carbon
atoms. 119Sn-NMR (C6D6): l 6.1 ppm. IR (KBr): w
3358 (m, NH) cm−1. MS (CI, isobutane): m/z 786
(MH+, 2%). Anal. Found: C, 73.23; H, 9.77; N, 1.74.
C48H75NSn (784.82) Anal. Calc.: C, 73.46; H, 9.63; N,
1.78%.
95.5(1) C(20)−Sn−C(31)
109.0(1) C(13)−Sn−C(20)
106.9(1) C(13)−C(14)−C(19) 123.9(2)
121.0(2)
85.8(1)
C(14)−C(13)−C(20) 111.9(3) C(19)−C(20)−Sn
109.3(3)
Scheme 3.
3.3. 2,4,6-Trimethylphenyl-[5,7-di-tert-butyl-3,3-
dimethyl)-1-(2,4,6-tri-tert-butylphenyl)-1-
stannaindan-1-yl]amine (8)
solid. Recrystallization from a minimum amount of
toluene furnished 0.90 g (44% yield) of rectangular
colourless crystals of 7, m.p. 196 °C. 1H-NMR (500
At 0°C, azide 4 (0.34 g, 2.13 mmol) was added from
a syringe to a solution of 1 (1.3 g, 2.13 mmol) in
n-hexane (50 ml) over a period of 1 h with stirring. To
complete the reaction, the solution was allowed to
warm to r.t. and stirred for 12 h. During this time the
colour of the solution changed from dark red to yellow.
The solution was concentrated to a volume of 30 ml
and cooled at 4°C. Recrystallization of the yellow solid
from a minimum amount of toluene yielded 0.60 g
(38%) of rectangular colourless plates of 8, m.p. 179°C.
1H-NMR (300 MHz, 298 K, C6D6): l 0.92 (s, 9 H), 1.20
(s, 9 H), 1.23 (s, 9 H), 1.34 (s, 9 H), 1.62 (s, 9 H), 1.63
2
(s, 3 H), 1.75 (d, 1 H, J=13.3 Hz), 1.76 (s, 3 H), 1.83
(s, 6 H), 1.89 (d, 1 H), 2.08 (s, 3 H), 2.70 (s, 1 H, NH),
4
6.55 (s, 2 H), 7.44 (d, 1 H, J=1.85 Hz), 7.46 (d, 1 H,
4
4J=1.95 Hz), 7.61 (d, 1 H, J=1.95 Hz), 7.65 (d, 1 H,
4J=1.85 Hz) ppm. 13C-NMR (298 K, C6D6): l 20.17
(Cp), 20.48 (Cp), 31.38 (CH2), 31.42 (Cp), 32.08 (Cp),
33.75 (Cp), 34.04 (Cp), 34.57 (Cq), 34.84 (Cq), 36.59
(Cp), 36.78 (Cq), 36.83 (Cp), 39.28 (Cq), 40.12 (Cq),
41.46 (Cq), 121.37 (Ct), 122.23 (Ct), 123.34 (Ct), 123.92
(Ct), 126.33 (Cq), 126.37 (Cq), 128.29 (Ct), 129.49 (Ct),
135.47 (Cq), 137.14 (Cq), 146.64 (Cq), 150.25 (Cq),
151.97 (Cq), 154.51 (Cq), 158.12 (Cq), 158.56 (Cq),
159.11 (Cq) ppm. 119Sn-NMR (C6D6, 298 K): l 10.5
ppm. IR (KBr) w: 3364 (m, NH) cm−1. Anal. Found:
C, 72.68; H, 9.40; N, 1.86. C45H68NSn (741.73) Anal.
Calc.: C, 72.87; H, 9.24; N, 1.89%.
Fig. 2. Molecular structure of 10 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability.
Table 2
Selected bond lengths (pm) and angles (°) for 10
Bond lengths (pm)
Sn−C(1)
N(1)−N(2)
220.5(2)
138.0(3)
Sn−N(1)
N(2)−N(2a)
210.0(2)
126.2(4)
Bond angles (°)
N(1)−Sn−N(1a)
Sn−N(1)−N(2)
72.9(1)
116.95(14)
N(1)−N(2)−N(2a) 116.5(1)
C(1)−Sn−C(1a) 108.2(1)

U. Fooken et al. / Journal of Organometallic Chemistry 579 (1999) 280–284
283
3.4. 5,5-Bis(2,4,6-tri-tert-butylphenyl)-1,4-bis[3,5-bis-
(trifluoromethyl)phenyl]-4,5-dihydro-1H-[1,2,3,4,5]tetr-
azastannole (10)
at 293(2) K on a Siemens STOE AED 2 (7) or at 213(2)
K on a STOE IPDS (10) diffractometer using graphite-
monochromated Mo–Ka radiation.
The structures were solved by direct phase determina-
tion and refined by full-matrix least-squares techniques
against F2 with the SHELXL 93 program system [15].
Hydrogen atoms were placed in the calculated positions,
and all other atoms were refined anisotropically [16]. The
fluorine atoms of the CF3 groups are disordered and
were refined on three positions with the occupancy factor
of 1/3 each.
At −40°C, azide 9 (1.06 g, 4.2 mmol) was added
dropwise to a solution of 1 (1.27 g, 2.1 mmol) in toluene
(40 ml). The mixture was allowed to warm to 0°C over
a period of 2.5 h. During this time the colour of the
solution changed from reddish–brown to yellowish–
brown. Concentration of the solution to a volume of 30
ml and cooling at 4°C afforded 1.2 g (52%) of pale yellow
rhombic crystals of 10, m.p. 135°C (dec.). 1H-NMR (500
MHz, 273 K, toluene-d8): l 0.76 (s, 18 H), 1.16 (s, 18 H),
1.34 (s, 18 H), 7.36 (s, 2 H), 7.53 (s, 2 H), 7.55 (s, 2 H),
8.14 (s, 4 H) ppm. 13C-NMR (298 K): l 30.90 (Cp), 32.68
(Cp), 33.12 (Cp), 34.66 (Cq), 37.94 (Cq), 39.20 (Cq), 117.98
Acknowledgements
Financial support of our work from the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen
Industrie is gratefully acknowledged.
1
(Ct), 123.83 (Cq, JC,F=272.8 Hz), 125.92 (Ct), 126.51
2
(Ct), 129.28 (Ct), 132.31 (Cq, JC,F=32.9 Hz), 140.67
(Cq), 150.79 (Cq), 152.10 (Cq), 154.76 (Cq), 156.01 (Cq)
ppm. 119Sn-NMR: l −275.0 ppm. UV/vis: umax(m): 296
(22440) nm. Anal. Found: C, 57.32; H, 5.82; N, 5.11.
C52H64F12N4Sn (1091.77) Anal. Calc.: C, 57.21, H, 5.91;
N, 5.13%.
References
[1] Compounds of germanium, tin, and lead; part IXXX. Part
XXVIII: M. Stu¨rmann, W. Saak, H. Marsmann, M. Weiden-
bruch, Angew. Chem. 111 (1999) 145; Angew. Chem. Int. Ed. 38
(1999) 187.
3.5. X-ray structure analyses of 7 and 10
[2] Review: M. Weidenbruch, Eur. J. Inorg. Chem. (1999) 373.
[3] M. Weidenbruch, J. Schlaefke, A. Scha¨fer, K. Peters, H.G. von
Schnering, H. Marsmann, Angew. Chem. 106 (1994) 1938;
Angew. Chem. Int. Ed. Engl. 33 (1994) 1846.
Crystal and numerical data of the structure determina-
tions are given in Table 3. Data collection was performed
[4] M. Weidenbruch, A. Stilter, J. Schlaefke, K. Peters, H.G. von
Schnering, J. Organomet. Chem. 501 (1995) 67.
[5] M. Weidenbruch, A. Stilter, K. Peters, H.G. von Schnering,
Chem. Ber. 129 (1996) 1565; Z. Anorg. Allg. Chem. 622 (1996)
543.
[6] M. Weidenbruch, A. Stilter, K. Peters, H.G. von Schnering, J.
Organomet. Chem. 560 (1998) 125.
[7] M. Weidenbruch, U. Grobecker, W. Saak, E.-M. Peters, K.
Peters, Organometallics 17 (1998) 5206.
[8] N. Wiberg, S.-K. Vasisht, Angew. Chem. 103 (1991) 105; Angew.
Chem. Int. Ed. Engl. 30 (1991) 93.
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Angew. Chem. Int. Ed. Engl. 30 (1991) 1017.
[10] G. Ossig, A. Meller, S. Freitag, R. Herbst-Irmer, J. Chem. Soc.,
Chem. Commun. (1993) 497.
[11] G.A. Miller, S.W. Lee, W.C. Trogler, Organometallics 8 (1989)
738.
Table 3
Crystallographic data for 7 and 10
7
10
Empirical formula
Molar mass
Unit cell dimensions
a (pm)
b (pm)
c (pm)
C47H75NSn
784.85
C56H64F12N4Sn
1091.82
1308.1(1)
1673.2(2)
2130.2(2)
90.26(2)
4644.0(8)
4
1.118
Monoclinic
P21/c
2129.65(10)
1000.24(4)
2617.06(8)
107.144(4)
5327.1(4)
4
1.361
Monoclinic
C2/c
i (°)
V (×106) (pm3)
Z
Dcalc (g cm−3
)
Crystal system
Space group
Crystal dimensions (mm3)
0.61×0.42
0.70×0.68×0.50
[12] J. Niesmann, U. Klingebiel, M. Noltemeyer, J. Organomet.
Chem. 521 (1996) 191.
[13] J. Pfeiffer, W. Maringele, M. Noltemeyer, A. Meller, Chem. Ber.
122 (1989) 245.
×0.32
ꢀ-scan
50
Data collection mode
2qmax (°)
–
52
No. of reflections
No. of unique reflections
No. of observed reflections
(I=2|(I))
8199
8199
6604
19458
4916
4493
[14] M. Veith, E. Werle, V. Huch, Z. Anorg. Allg. Chem. 619 (1993)
641.
[15] G.M. Sheldrick, SHELXL 93, Program for crystal structure
refinement, Universita¨t Go¨ttingen, Germany.
Linear abs. coefficient
0.577
433
0.524
417
[16] Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary
publication nos. CCDC-106609 (7) and CCDC-106610 (10).
Copies of the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambrige CB2 1EZ, UK [Fax:
+44-01223-336-093; e-mail: deposite@ccdc.cam.ac.uk].
(mm−1
)
No. of parameters
R1 (wR2) (I=2|(I))
R1 (wR2) (all data)
GOF on F2
0.0449 (0.1045) 0.0303 (0.0769)
0.0653 (0.1296) 0.0351 (0.0811)
1.167
1.086

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U. Fooken et al. / Journal of Organometallic Chemistry 579 (1999) 280–284
[17] For a recent review on the reactions of silenes with azides see:
A.G. Brook, M.A. Brook, in R. West, F.G.A. Stone (Eds.),
Multiply Bonded Main Group Metals and Metalloids, Academic
Press, San Diego, 1996, p. 71.
[18] For a recent review on the reactions of silanimines with azides
see: I. Hemme, U. Klingebiel, in: R. West, F.G.A. Stone (Eds.),
Multiply Bonded Main Group Metals and Metalloids, Academic
Press, San Diego, 1996, p. 159.
.