Synthesis and reactivity of intramolecularly stabilized organotin compounds containing the C,N-chelating o-carboranylamino ligand [o-C2B10H10(CH2NMe2)-C,N]- (CabC,N). X-ray structures of (CabC,N)SnR2X (R = Me, X = Cl; R = Ph, X = Cl), (CabC,N)2Hg, and

Article abstract of DOI:10.1021/om990935s

A variety of organotin complexes, containing the o-carboranylamino ligand (Cab^C,N), has been prepared by the reaction of LiCab^C,N (1) with organotin halides or tin tetrachloride. In this way, the tetraorganotin compound (Cab^C,N)SnMe₃ (2), triorganotin halide (Cab^C,N)SnR₂X (3: R = Me, X = Cl, 3a; R = Ph, X = Cl, 3b; R = Me, X = Br, 3c), diorganotin dichloride (Cab^C,N)SnPhCl₂ (4), and monoorganotin trichloride (Cab^C,N)SnCl₃ (5) have been synthesized and characterized. ¹H and ¹¹⁹Sn NMR spectroscopy indicates that the tin center in the tetraorganotin compound 2 is tetracoordinate, whereas this center in mono-, di-, and triorganotin compounds 3-5 is pentacoordinate as a result of intramolecular Sn-N coordination. Complexes 3a,c were also formed by redistribution of (Cab^C,N)SnMe₃ (2) with the corresponding Me₂SnX₂ (X = Cl, Br). The molecular structures of 3a,b were determined by X-ray analysis. As a result of the Sn-N interaction, the tin atoms in 3a,b exhibit distorted-trigonal-bipyramidal configurations with the electronegative atoms (N and Cl) in apical positions. The reaction of 2 equiv of 2 with HgCl₂ resulted in transmetalation of (Cab^C,N)SnMe₃ (2), giving the diorganomercury compound (Cab^C,N)₂Hg (6). The structure of 6 was determined by an X-ray structural study. The mercury atom is four-coordinate, both nitrogen atoms being involved in intramolecular coordination. The reaction of 3c with Na in a 1:1 ratio afforded the bis(o-carboranylamino)distannane [(Cab^C,N)SnMe₂]₂ (7). The crystal structure of 7 was determined by an X-ray structural study. The two four-coordinate tin moieties exhibit approximately pseudotetrahedral geometries showing only negligible, if any, interactions between the tin atoms and the amino nitrogen atoms.

Full text of DOI:10.1021/om990935s

Organometallics 2000, 19, 1695-1703
1695
Syn th esis a n d Rea ctivity of In tr a m olecu la r ly Sta bilized
Or ga n otin Com p ou n d s Con ta in in g th e C,N-Ch ela tin g
o-Ca r bor a n yla m in o Liga n d [o-C2B10H10(CH2NMe2)-C,N]-
(Ca bC,N). X-r a y Str u ctu r es of (Ca bC,N)Sn R2X (R ) Me, X )
†
Cl; R ) P h , X ) Cl), (Ca bC,N)2Hg, a n d [(Ca bC,N)Sn Me2]2
J ong-Dae Lee,‡ Sung-J oon Kim,‡ Dongwon Yoo,‡ J aejung Ko,*,‡ Sungil Cho,§ and
Sang Ook Kang*,‡
Department of Chemistry, Korea University, 208 Seochang, Chochiwon,
Chung-nam 339-700, Korea, and Department of Chemical Engineering, J unnong-dong 90,
Seoul City University, Seoul 130-743, Korea
Received November 29, 1999
A variety of organotin complexes, containing the o-carboranylamino ligand (CabC,N), has
been prepared by the reaction of LiCabC,N (1) with organotin halides or tin tetrachloride. In
this way, the tetraorganotin compound (CabC,N)SnMe3 (2), triorganotin halide (CabC,N)SnR2X
(3: R ) Me, X ) Cl, 3a ; R ) Ph, X ) Cl, 3b; R ) Me, X ) Br, 3c), diorganotin dichloride
(CabC,N)SnPhCl2 (4), and monoorganotin trichloride (CabC,N)SnCl3 (5) have been synthesized
1
and characterized. H and 119Sn NMR spectroscopy indicates that the tin center in the
tetraorganotin compound 2 is tetracoordinate, whereas this center in mono-, di-, and
triorganotin compounds 3-5 is pentacoordinate as a result of intramolecular Sn-N
coordination. Complexes 3a ,c were also formed by redistribution of (CabC,N)SnMe3 (2) with
the corresponding Me2SnX2 (X ) Cl, Br). The molecular structures of 3a ,b were determined
by X-ray analysis. As a result of the Sn-N interaction, the tin atoms in 3a ,b exhibit distorted-
trigonal-bipyramidal configurations with the electronegative atoms (N and Cl) in apical
positions. The reaction of 2 equiv of 2 with HgCl2 resulted in transmetalation of (CabC,N)-
SnMe3 (2), giving the diorganomercury compound (CabC,N)2Hg (6). The structure of 6 was
determined by an X-ray structural study. The mercury atom is four-coordinate, both nitrogen
atoms being involved in intramolecular coordination. The reaction of 3c with Na in a 1:1
ratio afforded the bis(o-carboranylamino)distannane [(CabC,N)SnMe2]2 (7). The crystal
structure of 7 was determined by an X-ray structural study. The two four-coordinate tin
moieties exhibit approximately pseudotetrahedral geometries showing only negligible, if any,
interactions between the tin atoms and the amino nitrogen atoms.
In tr od u ction
In this study, organotin complexes of the type (CabC,N)-
SnR1R2X (3-5), in which the tin center may be regarded
as pentacoordinate as a result of intramolecular Sn-N
coordination, have been prepared and characterized.
Such a Sn-N interaction in these compounds is favored
It has been well-established that by using the proper-
ties of C,N-chelating ligands,1 organometallic com-
pounds that have interesting properties and special
reactivity can be prepared. These properties are at-
tributable to an extension of their coordination number
by intramolecular coordination of a C,N-chelating ligand.
There is a variety of organotin halides with C,N-
chelating ligands which are bonded to the tin atom by
a Sn-C covalent bond and a Sn-N dative bond.2 It was,
therefore, of interest to investigate the possibility of
synthesizing such intramolecularly coordinated com-
plexes using the potentially bidentate C,N-chelating
o-carboranylamino ligand system LiCabC,N (1).3 In this
respect, we have started investigating the synthesis of
intramolecularly coordinated organotin compounds bear-
ing a bulky o-carborane unit4 that might potentially
stabilize the pentacoordinate tin center.
(2) (a) Rippstein, R.; Kickelbick, G.; Schubert, U. Inorg. Chim. Acta
1999, 290, 100. (b) Schwarzkopf, K.; Metzger, J . O.; Saak, W.; Pohl, S.
Chem. Ber. 1997, 130, 1539. (c) Hoppe, S.; Weichmann, H.; J urkschat,
K.; Schneider-Koglin, C.; Dra¨ger, M. J . Organomet. Chem. 1995, 505,
63. (d) J astrzebski, J . T. B. H.; van der Schaaf, P. A.; Boersma, J .; van
Koten, G.; de Ridder, D. J . A.; Heijdenrijk, D. Organometallics 1992,
11, 1521. (e) J astrzebski, J . T. B. H.; Boersma, J .; Esch, P. M.; van
Koten, G. Organometallics 1991, 10, 930. (f) Neumann, W. P.; Wicenec,
C. J . Organomet. Chem. 1991, 420, 171. (g) J astrzebski, J . T. B. H.;
Boersma, J .; van Koten, G. J . Organomet. Chem. 1991, 413, 43. (h)
J astrzebski, J . T. B. H.; Wehman, E.; Boersma, J .; van Koten, G.;
Goubitz, K.; Heijdenrijk, D. J . Organomet. Chem. 1991, 409, 157. (i)
Preut, H.; Wicenec, C.; Neumann, W. P. Acta Crystallogr., Sect. C 1991,
C47, 2214. (j) Vicente, J .; Chiote, M. T.; Ramirez-de-Arellano, M. d.
C.; J ones, P. G. J . Organomet. Chem. 1990, 394, 77. (k) J astrzebski,
J . T. B. H.; van Koten, G.; Knaap, C. T.; Schreurs, A. M. M. M.; Kroon,
J .; Spek, A. L. Organometallics 1986, 5, 1551. (l) Oki, M.; Ohira, M.
Chem. Lett. 1982, 1267. (m) van Koten, G.; J astrzebski, J . T. B. H.;
Noltes, J . G.; Verhoecks, G. J .; Spek, A. L.; Kroon, J . J . Chem. Soc.,
Dalton Trans. 1980, 1352. (n) van Koten, G.; J astrzebski, J . T. B. H.;
Noltes, J . G.; Pontenagel, W. M. G. F.; Kroon, J .; Spek, A. L. J . Am.
Chem. Soc. 1978, 100, 5021. (o) van Koten, G.; Noltes, J . G. J . Am.
Chem. Soc. 1976, 98, 5393. (p) van Koten, G.; Noltes, J . G. J .; Spek, A.
L. J . Organomet. Chem. 1976, 118, 183.
† This contribution is dedicated to Professor Dietmar Seyferth on
the occasion of his 70th birthday.
‡ Korea University.
§ Seoul City University.
(1) J astrzebski, J . T. B. H.; van Koten, G. Adv. Organomet. Chem.
1993, 35, 241 and references therein.
10.1021/om990935s CCC: $19.00 © 2000 American Chemical Society
Publication on Web 03/30/2000

1696 Organometallics, Vol. 19, No. 9, 2000
Lee et al.
in the solid state and in solution; in both cases neutral
o-carboranylamine is set free. It is moderately soluble
in pentane, benzene, and toluene.
The composition of 2 was confirmed by elemental
analysis and high-resolution mass spectral analysis. The
1
119Sn, 13C, 11B, and relevant H NMR spectroscopic data
for 2 are given in Table 1. The signals for both N(CH3)2
and NCH2 in the 1H NMR spectrum are at a higher field
1
than for the free ligand. The H NMR data suggest that
compound 2 is tetracoordinated in solution. This is
demonstrated most clearly by both the downfield shift
of the 119Sn NMR resonance at 35.38 ppm and the
by an electronegative substituent on tin, such as halo-
2
decrease in the J (119SnC1H3) coupling constant to 56.0
gen, trans to the Lewis-basic group. In contrast, tet-
Hz compared with those of Me3PhSn (δ(119Sn) -28.6
raorganotin compounds of the type (CabC,N)SnR1 R2 (2
2
2
ppm; J (119SnC1H3) ) 54.5 Hz)5a and Me2PhSnCl (δ-
and 7), bearing four Sn-C bonds, are reluctant to form
pentacoordinate complexes. In fact, at best only weak
interactions can be expected if electronegative substit-
uents are absent.1a A similar pentacoordinate arrange-
ment of the tin atom is in principle possible if the alkyl
substituents are replaced by electronegative substitu-
ents. Thus, the redistribution reaction of 2 with Me2-
SnX2 (X ) Cl, Br) gave the pentacoordinate triorganotin
compound 3, resulting in the formation of a stable Sn-N
bond. In addition, the intramolecularly stabilized dior-
ganomercury compound (CabC,N)2Hg (6) has been syn-
thesized by the transmetalation reaction of 2 with
HgCl2.
(
119Sn) 48.3 ppm; 2J (119SnC1H3) ) 58.5 Hz).6 Such a
correlation between δ(119Sn) and J (119SnC1H3) and the
tin coordination number is well-documented.5 Thus, the
main feature of the structure of 2 in solution is the
tetrahedral ligand arrangement around the tin atom.
Syn th esis of th e Tr ior ga n otin Ha lid es (Ca bC,N)-
Sn R2X (3). One procedure for the synthesis of 3 used
the reaction of 1 with the respective dialkyltin dihalide
(eq 2). Compounds 3 were purified by low-temperature
2
To the best of our knowledge, this is the first example
in which a C,N-chelating o-carboranylamino ligand is
intramolecularly coordinated with a tin atom, thus
improving the stability of the pentacoordinate tin center.
We now report the detailed synthesis and complete
characterization of a series of mono-, di-, tri-, and
tetraorganotin compounds containing the potentially
bidentate o-carboranylamino ligand.
Resu lts a n d Discu ssion
Syn th esis of th e Tetr a or ga n otin Com p lex (Ca b-
C,N)Sn Me3 (2). (CabC,N)SnMe3 (2) was prepared as a
colorless solid by the reaction of LiCabC,N (1) with a
stoichiometric amount of Me3SnCl according to eq 1. The
complex decomposes slowly in the presence of air, both
(3) Lee, J .-D.; Baek, C.-K.; Ko, J .; Park, K.; Cho, S.; Min, S.-K.; Kang,
S. O. Organometallics 1999, 18, 2189.
(4) Beall, H. In Boron Hydride Chemistry; Muetterties, E., Ed.;
Academic Press: New York, 1975; Chapter 9.

Intramolecularly Stabilized Organotin Compounds
Organometallics, Vol. 19, No. 9, 2000 1697
Ta ble 1. NMR Sp ectr oscop ic Da ta for Com p ou n d s 2-7
NMR (δ)a
compd
HCabN
1H
13C
11B
119Sn
2.33 (s, 6H, N-CH3)
3.00 (s, 2H, N-CH2)
46.73 (s, 2C, N-CH3)
-13.43 (d, 4B, J BH ) 120 Hz)
-11.87 (d, 2B, J BH ) 110 Hz)
-9.27 (d, 2B, J BH ) 160 Hz)
-5.48 (d, 1B, J BH ) 150 Hz)
-3.33 (d, 1B, J BH ) 140 Hz)
58.77 (s, 1C, CHCB10H10
63.23 (s, 1C, N-CH2)
75.75 (s, 1C, CHCB10H10
)
)
3.99 (s, 1H, H-Ccab
)
2
0.39 (s, 6H, Sn-CH3)
(56.0 Hz)b
2.26 (s, 6H, N-CH3)
2.90 (s, 2H, N-CH2)
1.20 (s, Sn-CH3)
61.73 (s, N-CH3)
62.77 (s, NCH2)
-13.04 (d, 6B, J BH ) 145 Hz)
-9.40 (d, 2B, J BH ) 155 Hz)
-3.96 (d, 1B, J BH ) 155 Hz)
-2.52 (d, 1B, J BH ) 150 Hz)
35.38
3a
1.00 (s, 6H, Sn-CH3)
3.26 (s, Sn-CH3)
51.20 (s, N-CH3)
65.58 (s, N-CH2)
-13.69 (d, 1B, J BH ) 150 Hz)
-11.19 (d, 2B, J BH ) 180 Hz)
-10.67 (d, 4B, J BH ) 155 Hz)
-7.19 (d, 2B, J BH ) 140 Hz)
-4.13 (d, 1B, J BH ) 130 Hz)
-13.14 (d, 1B, J BH ) 135 Hz)
-11.63 (d, 2B, J BH ) 170 Hz)
-9.44 (d, 3B, J BH ) 140 Hz)
-7.22 (d, 1B, J BH ) 155 Hz)
-3.59 (d, 2B, J BH ) 165 Hz)
-0.68 (d, 1B, J BH ) 155 Hz)
-121.44
-118.63
(69.6 Hz)b
2.39 (s, 6H, N-CH3)
3.19 (s, 2H, N-CH2)
3b
2.01 (s, 6H, N-CH3)
3.09 (s, 2H, N-CH2)
7.49 (m, 6H, N-C6H5)
7.75 (m, 4H, N-C6H5)
51.29 (s, N-CH3)
65.88 (s, N-CH2)
129.69 (Sn-C6H5)
(89.3 Hz)c
130.76 (Sn-C6H5)
(16.60 Hz)c
136.03 (Sn-C6H5)
(45.5 Hz)c
73.55 (C2B10 unit)
3c
4
1.11 (s, 6H, Sn-CH3)
(68.8 Hz)b
4.85 (s, Sn-CH3)
51.09 (s, N-CH3)
65.88 (s, N-CH2)
-10.47 (d, 5B, J BH ) 150 Hz)
-7.32 (d, 2B, J BH ) 135 Hz)
-3.98 (d, 2B, J BH ) 150 Hz)
-1.93 (d, 1B, J BH ) 160 Hz)
-8.32 (d, 4B, J BH ) 140 Hz)
-7.24 (d, 4B, J BH ) 145 Hz)
-4.88 (d, 1B, J BH ) 160 Hz)
-1.69 (d, 1B, J BH ) 150 Hz)
-109.82
-130.49
2.39 (s, 6H, N-CH3)
3.18 (s, 2H, N-CH2)
2.38 (s, 6H, N-CH3)
3.21 (s, 2H, N-CH2)
7.53 (m, 3H, N-C6H5)
7.61 (m, 2H, N-C6H5)
53.63 (s, N-CH3)
66.67 (N-CH2)
126.83 (Sn-C6H5)
131.32 (Sn-C6H5)
137.86 (Sn-C6H5)
5
6
7
2.74 (s, 6H, N-CH3)
3.36 (s, 2H, N-CH2)
51.29 (s, N-CH3)
63.26 (N-CH2)
-7.48 (d, 4B, J BH ) 160 Hz)
-6.68 (d, 4B, J BH ) 135 Hz)
-5.01 (d, 1B, J BH ) 145 Hz)
-1.84 (d, 1B, J BH ) 140 Hz)
-14.84 (d, 2B, J BH ) 160 Hz)
-10.72 (d, 5B, J BH ) 145 Hz)
-8.21 (d, 2B, J BH ) 160 Hz)
-4.64 (d, 1B, J BH ) 180 Hz)
-13.19 (d, 2B, J BH ) 145 Hz)
-11.66 (d, 1B, J BH ) 140 Hz)
-9.15 (d, 3B, J BH ) 145 Hz)
-5.41 (d, 1B, J BH ) 140 Hz)
-3.21 (d, 2B, J BH ) 160 Hz)
0.13 (d, 1B, J BH ) 160 Hz)
-149.15
77.06 (C2B10 unit)
2.42 (s, 6H, N-CH3)
3.14 (s, 2H, N-CH2)
49.40 (s, N-CH3)
63.06 (N-CH2)
0.69 (s, 6H, Sn-CH3)
(50.23 Hz)b
-2.88 (s, Sn-CH3)
47.08 (s, N-CH3)
65.67 (s, N-CH2)
8.11
(2610 Hz)e
(13.6 Hz)d
2.28 (s, 6H, N-CH3)
2.89 (s, 2H, N-CH2)
a
cn
d
All NMR spectra were recorded in CDCl3 at room temperature. b 2J (119Sn-1H). J (119Sn-13C), n ) 2, 3. 3J (119Sn-1H). e 1J (119Sn-
117Sn).
recrystallization from toluene as colorless crystals.
central tin atom has little effect on the δ(N(CH3)2) and
1
Satisfactory elemental analyses were obtained for 3, and
δ(NCH2) values in both the H and 13C NMR spectra.
1
the H, 11B, and 13C NMR spectral data are consistent
Information about the ligand geometry in solution at
tin in 3 was obtained from the 119Sn chemical shifts and
2J (119SnC1H3) values for 3a ,c. These depend on the
coordination number of the tin5 and are compared with
those of pentacoordinate methyl-substituted triorgano-
tin halides. The observed δ(119Sn) and 2J (119SnC1H3)
values suggest a pentacoordinate geometry at tin for
3a ,c. In fact, there is a close agreement of the NMR
spectroscopic data between 3a and (ArC,N)SnMe2Cl,8
with the presence of the bidentate o-carboranylamino
ligand (see Experimental Section).
Compounds 3 are moderately stable in air and de-
compose only slowly when in contact with moisture. The
kinetic stabilization of compounds 3 is due to the
formation of a five-membered chelate ring, thus blocking
1
the Sn atom from external nucleophilic attack. The H
NMR signals for both N(CH3)2 and NCH2 in 3a ,c are at
lower field than for the free ligand. This can be
explained on the basis of a trigonal-bipyramidal geom-
etry with amino and halide ligands in the axial positions
and evidence of Sn-N coordination in solution. This
observation is consistent with similar findings for the
general intramolecularly coordinated triorganotin ha-
lides of the ArC,N ligand system (ArC,N ) C6H4(CH2-
NMe2)-C,N)-.2n,o,7 The data for 3b also reveal that the
replacement of Me (3a ,c) by Ph (3b) groups on the
2
particularly the J (119SnC1H3) coupling constants (69.6
Hz in (CabC,N)SnMe2Cl (3a) and 63.9 Hz in (ArC,N)SnMe2-
Cl). The spectroscopic data indicate that complexes 3
1
have a related structure. On the basis of H, 13C, and
119Sn NMR spectroscopic studies, a trigonal-bipyramidal
structure for 3 in solution is proposed. This is as
expected, since in the triorganotin halides containing a
C,N-chelating ligand, normally the tin atom has a
trigonal-bipyramidal coordination geometry, as a result
of intramolecular coordination.1 It is anticipated that
the o-carboranyl carbon atom and two alkyl ligands are
at the equatorial sites, while the more electronegative
(5) (a) Wrackmeyer, B. Annu. Rep. NMR Spectrosc. 1985, 16, 73.
(b) Otera, J . J . Organomet. Chem. 1981, 221, 57. (c) Petrosyan, V. S.;
Yashina, N. S.; Reutov, O. A. Adv. Organomet. Chem. 1976, 14, 63.
(d) Mitchell, T. N. J . Organomet. Chem. 1973, 59, 189.
(6) Weichmann, H.; Schmoll, C. Z. Chem. 1984, 24, 390.
(7) van Koten, G.; Schaap, C. A.; Noltes, J . G. J . Organomet. Chem.
1975, 99, 157.
(8) Rippstein, R.; Kickelbick, G.; Schubert, U. Monatsh. Chem. 1999,
130, 385.

1698 Organometallics, Vol. 19, No. 9, 2000
Lee et al.
nitrogen atom of o-carboranylamine and the halide atom
reside at axial positions.
A second route to 3 involved the redistribution reac-
tion9 of the tetraorganotin compound (CabC,N)SnMe3 (2)
with 1 equiv of the corresponding dimethyltin dihalide
Me2SnX2 (X ) Cl, Br) (eq 3).
F igu r e 1. Molecular structure of (CabC,N)SnMe2Cl (3a ).
The thermal ellipsoids are drawn at the 30% probability
level.
Complex 3b crystallizes with two pairs of independent
molecules (molecules 1 and 2) in an orthorhombic unit
cell. The main feature of the structure is the intramo-
lecular coordination between tin and nitrogen with a
distorted-trigonal-bipyramidal arrangement as shown
in Figure 2, with selected bond lengths and bond angles
listed in Table 3. Thus, a similar C,N-chelate structure
is seen in 3b, where the amine N again coordinates to
an axial position opposite to the chlorine atom with the
three Sn-C bonds in equatorial positions. The two
molecules are identical and show slight differences in
bond distances and angles compared to each other. The
bite angle of C(1)-Sn(1)-N(1)/C(1′)-Sn(1′)-N(1′) is
only 74.5(3)/75.4(3)°, the N(1)-Sn(1)-Cl(1)/N(1′)-Sn-
(1′)-Cl(1′) configuration is bent to 167.3(2)/167.5(2)°,
and the Sn atom is displaced 0.248(6)/0.212(5) Å from
the (C(1), C(6), C(12))/(C(1′), C(6′), C(12′)) plane toward
the Cl ligand. The values of 2.701(8) Å in molecule 1
and 2.666(8) Å in molecule 2 for the Sn-N distance are
in the range observed for other pentacoordinate trior-
ganotin halides with Sn-N coordination.2c,g,n,p As a
consequence of the weak Sn-N interaction, the expected
shortening of the Sn-Cl bonds to 2.408(3) Å in molecule
1 and 2.421(3) Å in molecule 2 is observed.
The NMR spectra of these products were identical
with those of 3a ,c prepared by the method of eq 2.
Although this reaction requires overnight reflux in
benzene, its simple reaction path and facile product
isolation make this route attractive.
Molecu la r Geom etr y a n d Cr ysta l Str u ctu r e of
3a ,b. The molecular structure of 3a as determined by
X-ray crystallography is shown in Figure 1. The crystal-
lographic data are collected in Table 2, and the inter-
atomic distances and angles are listed in Table 3. In
compound 3a , a donor-acceptor interaction stronger
than that in 7 between the nitrogen atom of the amino
group and the tin center is found. This interaction leads
to a trigonal-bipyramidal coordination of the Sn atom
and places the three organic substituents in the equato-
rial plane. The Sn atom resides 0.133(6) Å below the
equatorial plane (C(1), C(6), C(7)), and the N(1)-Sn-
(1)-Cl(1) configuration deviates from linearity (168.9-
(1)°). Such a distortion originates mainly from the
formation of five-membered C,N-chelate bonding of the
bulky o-carboranylamino group with a bite angle (N(1)-
Sn(1)-C(1)) of 75.5(2)°. The value of 2.648(6) Å for the
Sn(1)-N(1) distance is in the range observed for other
pentacoordinated triorganotin halides with Sn-N
coordination.2c,g,n,p As a consequence of the Sn-N in-
teraction, the Sn(1)-Cl(1) distance (2.458(2) Å) is longer
than that found in tetracoordinate Me3SnCl (2.430 Å).10
The lengthening is of the same order of magnitude as
observed for other hypervalent triorganotin chlorides.11
The structures of 3a ,b agree with conclusions12 from
the solution NMR data on the general placement of
atoms in a trigonal-bipyramidal framework. However,
considerable distortions from an idealized trigonal bi-
pyramid are evident in the solid state. According to the
X-ray structure analysis of 3a ,b, it is most likely that
the structure as found in the solid state is retained in
solution. The sum of the Sn-N and Sn-Cl bonds
appears to be remarkably constant, revealing an inverse
correlation between the Sn-N and Sn-Cl distances.
Syn th esis of Mon o- an d Dior gan otin Com pou n ds
(Ca bC,N)Sn RCl2 (R ) P h , 4; R ) Cl, 5). (CabC,N)SnRCl2
(9) (a) Mitchell, T. N.; Godry, B. J . Organomet. Chem. 1996, 516,
133. (b) Fu, F.; Li, H.; Zhu, D.; Fang, Q.; Pan, H.; Tiekink, E. R. T.;
Kayser, F.; Biesemans, M.; Verbruggen, I.; Willem, R.; Gielen, M. J .
Organomet. Chem. 1995, 490, 163. (c) Hoppe, S.; Weichmann, H.;
J urkschat, K.; Schneider-Koglin, C.; Dra¨ger, M. J . Organomet. Chem.
1995, 505, 63. (d) Kolb, U.; Dra¨ger, M.; J ousseaume, B. Organometallics
1991, 10, 2737. (e) J astrzebski, J . T. B. H.; Knaap, C. T.; van Koten,
G. J . Organomet. Chem. 1983, 255, 287.
(11) (a) Hartung, H.; Petrick, D.; Schmoll, C.; Weichmann, H. Z.
Anorg. Allg. Chem. 1987, 550, 140. (b) Weichmann, H.; Meunier-Piret,
J .; van Meerssche, H. J . Organomet. Chem. 1986, 309, 267.
(10) Lefferts, J . L.; Molloy, K. C.; Hossain, M. B.; van der Helm, D.;
Zuckerman, J . J . J . Organomet. Chem. 1982, 240, 349.

Intramolecularly Stabilized Organotin Compounds
Organometallics, Vol. 19, No. 9, 2000 1699
Ta ble 2. X-r a y Cr ysta llogr a p h ic Da ta a n d P r ocessin g P a r a m eter s for Com p ou n d s 3a ,b, 6, a n d 7
3a
3b
6
7
formula
fw
B
10C7H24ClNSn
B10C17H28ClNSn
508.64
B20C10H36N2Hg
601.22
B20C14H48N2Sn2
698.12
384.51
cryst class
space group
Z
monoclinic
P21/c (No. 14)
4
orthorhombic
Pna21 (No. 33)
8
monoclinic
P21/c (No. 14)
4
monoclinic
P21/n (No. 14)
4
cell constants
a, Å
12.8470(3)
10.2730(4)
13.4510(4)
1739.34(9)
101.540(2)
1.603
20.4020(4)
8.3610(1)
27.3250(6)
4661.1(1)
103.715(7)
1.216
10.2530(7)
9.5172(8)
13.374(1)
1267.8(2)
92.8180(1)
12.120
16.8285(1)
9.8086(1)
20.1975(4)
3329.85(8)
b, Å
c, Å
V, Å3
â, deg
µ, cm-1
cryst size, mm
1.511
0.20 × 0.25 × 0.30
0.10 × 0.10 × 0.15
0.20 × 0.30 × 0.30
0.20 × 0.30 × 0.20
D
calcd, g/cm3
F(000)
1.468
1.450
1.575
1.393
1384
760
2032
850
radiation
Mo KR (λ ) 0.7170 Å)
θ range, deg
2.51-24.80
+15, (11, (15
2936
2.00-24.74
+24, (9, (32
4063
2.04-24.97
(12, +11, +15
2405
1.54-23.25
(17, (7, +21
14 454
4752
h, k, l collected
no. of rflns measd
no. of unique rflns
2936
4063
2225
no. of rflns used in refinement (I > 2σ(I))
2936
4063
2225
4752
no. of params
data/param ratio
R1a
277
765
163
367
10.60
5.31
13.65
12.95
0.0556
0.1228
1.134
0.0420
0.1119
0.954
0.0507
0.1338
1.170
0.0468
0.1122
0.792
wR2b
GOF
R1 ) ∑||Fo| - |Fc||/∑|Fo| (based on reflections with Fo > 2σ(Fo2)). wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]1/2; w ) 1/[σ2(Fo2) + (0.095P)2];
a
2
b
2
P ) [max(Fo2, 0) + 2Fc2]/3 (also with Fo > 2σ(Fo2)).
2
(R ) Ph, 4; R ) Cl, 5) were prepared as colorless solids
by the reaction of 1 with a stoichiometric amount of
RSnCl3 (R ) Ph, Cl) according to eq 4. Complexes 4 and
5 are stable in air and show slow decomposition when
in contact with moisture.
with respect to the tetracoordinate Me2SnCl2 (δ(119Sn)
140 ppm).14 This confirms the existence of the transan-
nular donor-acceptor interaction in this molecule in
solution. The same holds for monoorganotin halide 5 (δ-
(
119Sn) -149.15 ppm) when compared with MeSnCl3
(δ(119Sn) 21 ppm).14 Taken together, these data favor
the existence of an intramolecular Sn-N interaction in
4 and 5, which leads to a trigonal-bipyramidal coordina-
tion of the Sn atom.
Tr a n sm eta la tion of th e Tetr a or ga n otin Com p lex
(Ca bC,N)Sn Me3 (2) w ith HgCl2. The reaction of 2 equiv
of 2 with HgCl2 afforded (CabC,N)2Hg 6 in 46% yield (eq
5).
The compositions of 4 and 5 were confirmed by
elemental analysis and high-resolution mass spectral
analysis. Because mono- and diorganotin halides are
stronger Lewis acids than a triorganotin halide,13 the
intramolecular Sn-N coordination which was observed
earlier in the corresponding triorganotin halide 3 should
also occur in compounds 4 and 5. To assess the strength
of such intramolecular Sn-N interactions in 4 and 5,
solution NMR data for these compounds were compared
with those of the triorganotin halides 3a -c. Large
downfield shifts of the signals for both N(CH3)2 and
1
(12) (a) Mu¨gge, C.; J urkschat, K.; Tzschach, A.; Zschunke, A. J .
Organomet. Chem. 1979, 164, 135. (b) J urkschat, K.; Mu¨gge, C.;
Tzschach, A.; Zschunke, A.; Larin, M. F.; Pestunovich, V. A.; Voronkov,
M. G. J . Organomet. Chem. 1977, 139, 279.
(13) Dostal, S.; Stoudt, S. J .; Fanwick, P.; Sereatan, W. F.; Kahr,
B.; J ackson, J . E. Organometallics 1993, 12, 2284.
(14) Davis A. G. Organotin Chemistry; VCH: Weinheim, Germany,
1997.
NCH2 are observed in the H NMR spectra of 4 and 5,
in accord with the presence of strong Sn-N bonds.
Additional evidence for pentacoordinate tin centers in
these compounds is the observed absolute 119Sn NMR
chemical shift values. The diorganotin halide 4 exhibits
a considerable high-field shift (δ(119Sn) -130.49 ppm)

1700 Organometallics, Vol. 19, No. 9, 2000
Ta ble 3. Selected In ter a tom ic Dista n ces a n d An gles in 3a ,b, 6, a n d 7
Lee et al.
Bond Distances (Å)
Compound 3a
Sn(1)-N(1)
Sn(1)-C(6)
N(1)-C(4)
C(1)-C(2)
2.648(6)
2.120(9)
1.49(1)
Sn(1)-Cl(1)
Sn(1)-C(7)
N(1)-C(5)
2.458(2)
2.121(9)
1.47(1)
Sn(1)-C(1)
N(1)-C(3)
C(2)-C(3)
2.194(6)
1.47(1)
1.52(1)
1.641(9)
Compound 3b
Molecule 1
Sn(1)-Cl(1)
Sn(1)-C(12)
N(1)-C(5)
Sn(1)-N(1)
Sn(1)-C(6)
N(1)-C(4)
C(1)-C(2)
2.701(8)
2.11(1)
1.49(2)
1.64(1)
2.408(3)
2.15(1)
1.48(2)
Sn(1)-C(1)
N(1)-C(3)
C(2)-C(3)
2.20(1)
1.46(2)
1.55(2)
Molecule 2
Sn(1′)-N(1′)
Sn(1′)-C(6′)
N(1′)-C(4′)
C(1′)-C(2′)
2.666(8)
2.14(1)
1.51(2)
1.64(1)
Sn(1′)-Cl(1′)
Sn(1′)-C(12′)
N(1′)-C(5′)
2.421(3)
2.14(1)
1.45(2)
Sn(1′)-C(1′)
N(1′)-C(3′)
C(2′)-C(3′)
2.18(1)
1.48(2)
1.51(2)
Compound 6
Hg(1)-N(1)
Hg(1)-C(1)
C(2)-C(3)
2.092(8)
1.55(1)
2.86(6)
1.66(1)
N(1)-C(3)
1.46(1)
C(1)-C(2)
Compound 7
Sn(1)-Sn(1′)
Sn(1)-C(1)
Sn(1′)-C(1′)
N(1)-C(5)
N(1′)-C(3′)
C(2′)-C(3′)
2.8058(8)
2.216(8)
2.221(8)
1.48(1)
1.45(1)
1.55(1)
Sn(1)-C(6)
Sn(1′)-C(6′)
N(1)-C(3)
C(2)-C(3)
N(1′)-C(4′)
C(1′)-C(2′)
2.132(8)
2.136(8)
1.44(1)
1.51(1)
1.47(1)
1.66(1)
Sn(1)-C(7)
Sn(1′)-C(7′)
N(1)-C(4)
C(1)-C(2)
N(1′)-C(5′)
2.147(8)
2.149(8)
1.48(1)
1.69(1)
1.48(1)
Bond Angles (deg)
Compound 3a
C(6)-Sn(1)-C(1)
C(7)-Sn(1)-Cl(1)
C(5)-N(1)-C(4)
C(6)-Sn(1)-C(7)
C(6)-Sn(1)-Cl(1)
C(5)-N(1)-C(3)
N(1)-Sn(1)-Cl(1)
131.2(4)
93.1(3)
110.1(7)
168.9(1)
115.9(4)
94.0(3)
106.5(8)
C(7)-Sn(1)-C(1)
C(1)-Sn(1)-Cl(1)
C(3)-N(1)-C(4)
111.7(3)
93.6(2)
109.8(7)
Compound 3b
Molecule 1
C(6)-Sn(1)-C(1)
C(12)-Sn(1)-Cl(1)
C(3)-N(1)-C(4)
C(6)-Sn(1)-C(12)
C(6)-Sn(1)-Cl(1)
C(3)-N(1)-C(5)
N(1)-Sn(1)-Cl(1)
122.6(4)
98.4(3)
109(1)
120.0(4)
97.4(3)
110(1)
C(12)-Sn(1)-C(1)
C(1)-Sn(1)-Cl(1)
C(5)-N(1)-C(4)
113.5(4)
93.9(3)
107(1)
167.3(2)
Molecule 2
C(12′)-Sn(1′)-C(6′)
C(12′)-Sn(1′)-Cl(1′)
C(5′)-N(1′)-C(3′)
N(1′)-Sn(1′)-Cl(1′)
121.9(4)
95.7(3)
110(1)
C(12′)-Sn(1′)-C(1′)
C(6′)-Sn(1′)-Cl(1′)
C(5′)-N(1′)-C(4′)
114.0(4)
97.6(3)
107(1)
C(6′)-Sn(1′)-C(1′)
C(1′)-Sn(1′)-Cl(1′)
C(3′)-N(1′)-C(4′)
121.2(4)
93.4(3)
108(1)
167.5(2)
Compound 6
N(1)-Hg(1)-C(1)
C(3)-C(2)-C(1)
C(1)-Hg(1)-C(1)*
N(1)-C(3)-C(2)
180.000(2)
113.9(8)
75.0(9)
121.8(7)
Hg(1)-N(1)-C(3)
C(2)-C(1)-Hg(1)
104.2(9)
118.9(5)
Compound 7
C(6)-Sn(1)-C(7)
C(6)-Sn(1)-Sn(1′)
C(6′)-Sn(1′)-C(7′)
C(6′)-Sn(1′)-Sn(1)
C(3)-N(1)-C(4)
112.9(4)
118.8(3)
113.3(4)
118.1(2)
111.6(8)
110.9(7)
C(6)-Sn(1)-C(1)
C(7)-Sn(1)-Sn(1′)
C(6′)-Sn(1′)-C(1′)
C(7′)-Sn(1′)-Sn(1)
C(3)-N(1)-C(5)
106.0(3)
106.0(3)
109.8(3)
105.2(3)
113.1(8)
110.6(7)
C(7)-Sn(1)-C(1)
C(1)-Sn(1)-Sn(1′)
C(7′)-Sn(1′)-C(1′)
C(1′)-Sn(1′)-Sn(1)
C(4)-N(1)-C(5)
108.6(3)
103.9(2)
106.5(3)
103.0(2)
108.5(8)
108.5(7)
C(3′)-N(1′)-C(4′)
C(3′)-N(1′)-C(5′)
C(4′)-N(1′)-C(5′)
The composition of 6 was established by elemental
analysis. Furthermore, the spectroscopic data (1H, 11B,
and 13C NMR) for (CabC,N)2Hg (6) also are consistent
with its assigned structure. The 1H NMR spectrum
consists of a singlet due to the NMe2 at 2.42 ppm and a
singlet due to the NCH2 protons at 3.14 ppm. Further-
more, the appearance of the NMe2 proton signals at
lower field relative to the chemical shift of these protons
in the free ligand HCabN also provides evidence for
Hg-N coordination. This observation is consistent with
similar findings for the general intramolecularly coor-
dinated metal complexes of the o-carboranylamino
ligand system.3
square planar, the preferred geometry in almost in all
cases where such intramolecularly stabilized four-
coordination has been observed.15 The geometry about
the Hg atom is planar, and this atom also lies close to
coplanarity with both coordinating o-carboranylamino
units. The C-Hg-C axis is constrained exactly to
linearity by crystallographic symmetry with an Hg-C
distance of 2.092(8) Å, in close agreement with values
reported previously for (ArC,N)2Hg (2.10(2) Å)15b and
other diarylmercury compounds.16 The Hg(1)-N(1) dis-
tance (2.86(6) Å) is only slightly shorter than that in
(ArC,N)2Hg (2.89(1) Å),15b and it is still in the range of
bonding interaction.17
Molecu la r Geom etr y a n d Cr ysta l Str u ctu r e of 6.
Figure 3 and Table 3 show the ORTEP drawing and
selected bond distances and bond angles for the struc-
ture of 6, as determined by X-ray crystallography. The
coordination geometry around Hg is best described as
(15) (a) Schumann, H.; Freitag, S.; Girgsdies, F.; Hemling, H.;
Kociok-Ko¨hn, G. Eur. J . Inorg. Chem. 1998, 243. (b) Atwood, J . L.;
Berry, D. E.; Stobart, S. R.; Zaworotko, M. J . Inorg. Chem. 1983, 22,
3480.

Intramolecularly Stabilized Organotin Compounds
Organometallics, Vol. 19, No. 9, 2000 1701
tin centers (eq 6). The reaction of 3c with 10 equiv of
F igu r e 2. ORTEP plots of the molecule (CabC,N)SnPh2Cl
(3b), showing the two independent molecules in the asym-
metric unit. The atoms are drawn with 30% probability
ellipsoids. Hydrogen atoms are omitted for clarity.
sodium in toluene at mild reflux for 12 h gave the
distannane [(CabC,N)SnMe2]2 (7) in 18% isolated yield.
The composition of 7 was established by elemental
analysis. The spectroscopic data (1H, 11B, and 13C NMR)
for 7 also are consistent with its assigned structure. In
1
the H and 13C NMR spectra, the respective NCH2 and
NMe2 resonances show only small upfield shifts. The
1
solution H NMR spectrum of the tetraorganotin com-
pound 7 points to a structure in which there is tetra-
hedral geometry about Sn (see complex 2) instead of the
trigonal-bipyramidal geometry present in 3-5. Further-
more, one signal was observed for the two methyl groups
of the two magnetically equivalent dimethylamino
groups in 7, indicating that the rotation around the tin-
tin bond is not hindered due to any interaction between
Sn and N atoms. In addition, the Sn(CH3)2 protons in
1
2
the H NMR spectrum have a J (119Sn-C1H3) value of
about 50.2 Hz, which is the value expected for tetraco-
ordinate organotin compounds. In the 119Sn NMR
spectrum, the value of 2610 Hz of the J (119Sn-117Sn)
1
coupling constant also is characteristic of tetracoordi-
nate tin atoms, because couplings in distannanes lie in
the range 60-4500 Hz when the tin atoms are four-
coordinate.5a,18 On the basis of 1H, 13C, and 119Sn
solution NMR spectroscopic studies, a tetrahedral con-
formation at the tin atom for the bis(o-carboranylami-
no)distannane 7 may be assumed.
Molecu la r Geom etr y a n d Cr ysta l Str u ctu r e of 7.
The structure of complex 7 was determined by X-ray
diffraction. The crystallographic data are collected in
Table 2, and selected bond distances and angles are
summarized in Table 3. The ORTEP view of 7 is shown
in Figure 4. The structure of 7 agrees with the conclu-
sion based on the NMR data for the general placement
F igu r e 3. Molecular structure of (CabC,N)2Hg (6). The
thermal ellipsoids are drawn at the 30% probability level.
Syn th esis of th e Bis(o-ca r bor a n yla m in o)d ista n -
n a n e [(Ca bC,N)Sn Me2]2 (7). The Wurtz-type coupling
reaction of 3c using sodium metal afforded the corre-
sponding distannane containing pseudo-tetracoordinate
(16) (a) Vincente, J .; Bermudez, M.-D.; Carrion, F.-J .; J ones, P. G.
Chem. Ber. 1996, 129, 1395. (b) Holloway, C. E.; Melnik, M. J .
Organomet. Chem. 1995, 495, 1. (c) Black, D. S. C.; Deacon, G. B.;
Edwards, G. L.; Gatehouse, B. M. Aust. J . Chem. 1993, 46, 1323. (d)
Huffman, J . C.; Nugent, W. A.; Kochi, J . K. Inorg. Chem. 1980, 19,
2749. (e) Gardenic, D.; Kamenar, B.; Nagl, A. Acta Crystallogr., Sect.
B 1977, B33, 587. (f) Kunchur, N. R.; Mathew, M. J . Chem. Soc., Chem.
Commun. 1966, 71.
(18) (a) Adams, S.; Dra¨ger, M.; Mathiasch, B. Z. Allg. Chem. 1986,
532, 81. (b) Mathiasch, B.; Mitchell, T. N. J . Organomet. Chem. 1980,
185, 351. (c) Mitchell, T. N.; Walter, G. J . Chem. Soc., Perkin Trans.
2 1977, 1842.
(17) (a) Canty, A. J .; Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225.
(b) Canty, A. J .; Gatehouse, B. M. J . Chem. Soc., Dalton Trans. 1976,
2018.

1702 Organometallics, Vol. 19, No. 9, 2000
Lee et al.
HE-493 drybox. THF was freshly distilled from potassium
benzophenone. Diethyl ether and toluene were dried over and
distilled from sodium benzophenone. Hexane and pentane
were dried and distilled from CaH2. 1H, 11B, 13C, and 119Sn
NMR spectra were recorded on a Varian Gemini 2000 spec-
trometer operating at 200.1, 64.2, 50.3, and 74.6 MHz,
respectively. Chemical shifts are reported (δ, ppm) from
internal tetramethylsilane for 1H and 13C, from boron trifluo-
ride diethyl etherate for 11B, or from tetramethyltin for 119Sn
spectroscopy. IR spectra were recorded on a Biorad FTS-165
spectrophotometer. High- and low-resolution mass spectra
were obtained on a VG Micromass 7070H mass spectrometer.
Elemental analyses were performed with a Carlo Erba Instru-
ments CHNS-O EA1108 analyzer. All melting points are
uncorrected. Decaborane and (dimethylamino)-2-propyne were
purchased from the Callery Chemical Co. and Aldrich, respec-
tively, and used without purification. HCabN (o-C2B10H11(CH2-
NMe2)-N) was prepared by the literature methods.24
Syn th esis of (Ca bC,N)Sn Me3 (2). To a stirred solution of
HCabN (0.604 g, 3.0 mmol) in 30 mL of hexane, which was
cooled to -20 °C, was added 1.6 M n-BuLi (2 mL, 3.2 mmol)
via syringe. The resulting white suspension was stirred at -20
°C for 2 h and then transferred through a cannula to a
suspension of Me3SnCl (0.598 g, 3.0 mmol) in 30 mL of THF
at -78 °C. The reaction temperature was maintained at -78
°C for 1 h, following which the reaction mixture was warmed
slowly to room temperature. After being stirred for an ad-
ditional 12 h, the reaction mixture was filtered. The solvent
was removed under vacuum, and the resulting residue was
taken up in a minimum of toluene and then recrystallized from
this solution by cooling it to -20 °C. (CabC,N)SnMe3 (2) was
isolatedin47%yield(0.513g,1.4mmol).HRMSfor11B1012C81H2714N119Sn
(m/e): calcd, 367.2096; found, 367.2100. Anal. Calcd: C, 26.39;
H, 7.47; N, 3.85. Found: C, 26.40; H, 7.55; N, 3.80. Mp: 187-
188 °C. IR (KBr pellet, cm-1): ν(CH) 3068, 2984; ν(BH) 2588.
Gen er al Syn th esis of th e Tr ior gan otin Halides (CabC,N)-
Sn R2X (3). A solution of R2SnX2 in diethyl ether (20 mL) was
slowly added to a 50 mL diethyl ether solution of LiCabC,N (1;
3.0 mmol, previously prepared by the reaction of HCabN and
LiBun) at -78 °C. LiCl precipitated upon warming the mixture
to room temperature. The reaction mixture was stirred for 12
h at room temperature, after which all volatile components
were distilled in vacuo at room temperature. The crude product
was dissolved in toluene (40 mL) and the solution separated
by filtration. The volume was then reduced to 20 mL, and
crystallization at -20 °C gave pure 3.
P r ep a r a tive a n d An a lytica l Da ta for th e Tr ior ga n otin
Ha lid es (Ca bC,N)Sn R2X 3 (R ) Me, X ) Cl, 3a ; R ) P h , X
) Cl, 3b; R ) Me, X ) Br , 3c). (Ca bC,N)Sn Me2Cl (3a ) was
prepared from 3.0 mmol (0.659 g) of Me2SnCl2. After recrys-
tallization from toluene, 3a (0.323 g, 0.84 mmol, 28% yield)
was isolated as a white solid. Anal. Calcd: C, 21.87; H, 6.29;
N, 3.64. Found: C, 21.92; H, 6.34; N, 3.70. Mp: 197-198 °C.
IR spectrum (KBr pellet, cm-1): ν(CH) 2925, 2886; ν(BH) 2588.
(Ca bC,N)Sn P h 2Cl (3b) was prepared from 3.0 mmol (1.03
g) of Ph2SnCl2. After recrystallization from toluene, 3b (0.473
g, 0.93 mmol, 31% yield) was isolated as a white solid. Anal.
Calcd: C, 40.14; H, 5.55; N, 2.75. Found: C, 40.18; H, 5.63;
N, 2.70. Mp: 211-212 °C. IR spectrum (KBr pellet, cm-1):
ν(CH) 3071, 3051; ν(BH) 2607, 2584.
F igu r e 4. Molecular structure of [(CabC,N)SnMe2]2 (7). The
thermal ellipsoids are drawn at the 30% probability level.
of atoms in a tetrahedral framework. However, consid-
erable distortions from an idealized tetrahedron are
evident in the solid state. It must be noted that the
Sn-N distances in 7 are extremely long (average 3.640-
(8) Å). These values, although longer than the sum of
the covalent radii for nitrogen and tin (2.10 Å),19 are
shorter than the sum of the van der Waals radii (3.75
Å).20 The tetrahedral angles range from 103 to 119°, but
if the C(6)-Sn(1)-Sn(1′) and C(6′)-Sn(1′)-Sn(1) angles
are excluded, the range is somewhat smaller: i.e., 103-
113°. Because of steric hindrance by the two bulky
o-carboranyl groups, the two four-coordinate moieties
of the molecule are twisted by about 120° along the Sn-
Sn vector: the dihedral angle between the planes Sn-
(1)-Sn(1)′-C(1)′ and Sn(1′)-Sn(1)-C(1) is 19.6(2)°. The
Sn-C distances do not exhibit noteworthy differences
with respect to those of other four-coordinate organotin
compounds. It must be noted that the Sn-Sn bond
length in 7 is extremely long (2.806(1) Å) for a Sn-Sn
coordination bond,21 while this value is almost the same
as that found in [ClSn(CH2CH2CH2)2NMe]2 (2.83 Å).22
However, this Sn-Sn distance is in the range of lengths
found in compounds containing tin atoms with bulky
substituents.23 It is reasonable to assume that in 7 the
central Sn-Sn bond is elongated due to the steric
repulsion between the two o-carboranylamino ligands.
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were performed
under a dry, oxygen-free nitrogen or argon atmosphere using
standard Schlenk techniques or in a Vacuum Atmosphere
(19) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1973; p 224.
(20) Bondi, A. J . Phys. Chem. 1964, 68, 441.
(21) (a) Preut, H.; Bleckmann, P.; Mitchell, T.; Fabisch, B. Acta
Crystallogr., Sect. C 1984, C40, 370. (b) Dra¨ger, M.; Mathiasch, B.
Angew. Chem. 1981, 93, 1079. (c) Dra¨ger, M.; Mathiasch, B. Z. Anorg.
Allg. Chem. 1980, 470, 45. (d) Mathiasch, B.; Dra¨ger, M. Angew. Chem.
1978, 90, 814. (e) Nardelli, M.; Pelizzi, C.; Pelizzi, G.; Tarasconi, P. Z.
Anorg. Allg. Chem. 1977, 431, 250.
(22) J urkschat, K.; Tzschach, A.; Mu¨gge, C.; Piret-Meunier, J .; Van
Meerssche, M.; Van Binst, G.; Wynants, C.; Gielen, M.; Willem, R.
Organometallics 1988, 7, 593.
(Ca bC,N)Sn Me2Br (3c) was prepared from 3.0 mmol (0.926
g) of Me2SnBr2. After recrystallization from toluene, 3c (0.682
g, 1.59 mmol, 53% yield) was isolated as a white solid. Anal.
Calcd: C, 19.60; H, 5.64; N, 3.27. Found: C, 19.64; H, 5.69;
N, 3.19. Mp: 184-185 °C. IR spectrum (KBr pellet, cm-1):
ν(CH) 2979, 2924; ν(BH) 2597, 2570, 2551.
(23) (a) Adams, S.; Dra¨ger, M. J . Organomet. Chem. 1985, 288, 295.
(b) Masamune, S.; Sita, L. J . Am. Chem. Soc. 1983, 105, 630. (c) Belsky,
V.; Zemly, N.; Kolosava, N.; Borisova, I. J . Organomet. Chem. 1981,
215, 41.
(24) Heying, T. L.; Ager, J . W., J r.; Clark, S. L.; Mangold, D. J .;
Goldstein, H. L.; Hillman, M.; Polak, R. J .; Szymanski, J . W. Inorg.
Chem. 1963, 2, 1089.

Intramolecularly Stabilized Organotin Compounds
Organometallics, Vol. 19, No. 9, 2000 1703
Rea ction of (Ca bC,N)Sn Me3 (2) w ith Me2Sn Cl2. To a
solution of 0.364 g (1.0 mmol) of 2 in benzene (15 mL) was
added 0.220 g (1.0 mmol) of Me2SnCl2. The solution was heated
at 80-90 °C until the reaction was complete (ca. 12 h). The
progress of the reaction could easily be followed by NMR
spectroscopy. The mixture was then evaporated, and the
residue was extracted with toluene, filtered, and crystallized
from toluene to afford 0.138 g (0.36 mmol, 36%) of 3a .
Rea ction of (Ca bC,N)Sn Me3 (2) w ith Me2Sn Br 2. With
Me2SnBr2 (0.309 g, 1.0 mmol) as the starting material, the
synthesis of 3c was analogous to the preparation of 3a . 3c was
obtained in 42% yield (0.180 g, 0.42 mmol).
20.06; H, 6.08; N, 4.59. Mp: 158 °C. IR spectrum (KBr pellet,
cm-1): ν(CH) 2993, 2891; ν(BH) 2583, 2557, 2529.
Syn th esis of th e Bis(o-ca r bor a n yla m in o)d ista n n a n e
[(Ca bC,N)Sn Me2]2 (7). A solution of 0.429 g (1.0 mmol) of 3c
in 15 mL of toluene was added to Na (0.230 g, 10.0 mmol),
stirred in 15 mL of toluene. The heterogeneous mixture was
1
gently refluxed and monitored periodically by H NMR spec-
troscopy. After ca. 90% conversion (ca. 12 h), the gray solution
was evaporated to dryness. Hexane (10 mL) was added and
again stripped off under vacuum to remove traces of 3c,
leaving a yellow to brown solid. The residue was washed with
toluene (15 mL). Recrystallization from a toluene/hexane
mixture gave white microcrystals of [(CabC,N)SnMe2]2 (7),
which was isolated by filtration, washed with cold pentane (3
× 5 mL), and dried under vacuum (0.126 g, 0.18 mmol, 18%
yield). Anal. Calcd: C, 24.09; H, 6.93; N, 4.01. Found: C, 24.11;
H, 7.00; N, 3.97. Mp: 164-165 °C. IR spectrum (KBr pellet,
cm-1): ν(CH) 2831; ν(BH) 2574.
X-r a y Cr ysta llogr a p h y. Details of the crystal data and a
summary of intensity data collection parameters for 3a ,b, 6,
and 7 are given in Table 2. Crystals of 3a ,b, 6, and 7 were
grown from toluene solutions stored at -20 °C and were
mounted in thin-walled glass capillaries that were sealed
under argon. The data sets for 3a ,b were collected on a Rigaku
diffractometer with an area detector at a temperature of 195
K, and an Enraf CAD4 automated diffractometer was used
for the collection of data for compounds 6. A standard Siemens
SMART CCD area detector was used for the collection of data
for compound 7 at 223 K. Mo KR radiation (λ ) 0.7107 Å) was
used for all structures. Each structure was solved by the
application of direct methods using the SHELXS-96 program25a
and least-squares refinement using SHELXL-97.25b All non-
hydrogen atoms in compounds 3a ,b, 6, and 7 were refined
anisotropically. All other hydrogen atoms were located from
the difference Fourier and were refined.
Syn th esis of (Ca bC,N)Sn P h Cl2 (4). A solution of PhSnCl3
(0.50 mL, 3.2 mmol) in diethyl ether (20 mL) was slowly added
to a 50 mL diethyl ether solution of 1 (3.0 mmol) at -78 °C.
The reaction temperature was maintained at -78 °C for 1 h,
following which the reaction mixture was warmed slowly to
room temperature. After it had been stirred for an additional
12 h, the reaction mixture was filtered. The solvent was
removed under vacuum, and the resulting residue was taken
up in a minimum of toluene and recrystallized from this
solution by cooling to -20 °C. (CabC,N)SnPhCl2 (4) was isolated
11
12
35
in 35% yield (0.490 g, 1.05 mmol). HRMS for
B
C
-
11
10
Cl2 H2314N119Sn (m/e): calcd, 496.1160; found, 496.1165. Anal.
Calcd.: C, 28.29; H, 4.96; N, 3.00. Found: C, 28.20; H, 4.89;
N, 2.89. Mp: 215-216 °C. IR spectrum (KBr pellet, cm-1):
ν(CH) 3035, 2962; ν(BH) 2598.
1
Syn th esis of (Ca bC,N)Sn Cl3 (5). A solution of SnCl4 (0.35
mL, 3.0 mmol) in diethyl ether (20 mL) was slowly added to a
50 mL diethyl ether solution of 1 (3.0 mmol) at -78 °C. The
reaction temperature was maintained at -78 °C for 1 h,
following which the reaction mixture was warmed slowly to
room temperature. After it had been stirred for an additional
12 h, the reaction mixture was filtered. The solvent was
removed under vacuum, and the resulting residue was taken
up in a minimum of toluene and recrystallized by cooling to
-20 °C. (CabC,N)SnCl3 (5) was isolated in 86% yield (1.097 g,
Ack n ow led gm en t. We are grateful to the Korea
Science and Engineering Foundation (Grant No. 971-
0306-048-2) for financial support.
11
1
2.58 mmol). HRMS for
B
12C535Cl3 H1814N119Sn (m/e): calcd,
10
427.0457; found, 427.0451. Anal. Calcd: C, 14.12; H, 4.27; N,
3.29. Found: C, 14.20; H, 4.35; N, 3.20. Mp: 196-198 °C. IR
spectrum (KBr pellet, cm-1): ν(CH) 3037, 2961; ν(BH) 2582.
Rea ction of (Ca bC,N)Sn Me3 (2) w ith HgCl2. To a solution
of 0.728 g (2.0 mmol) of 2 in toluene (15 mL) was added 0.326
g (1.2 mmol) of HgCl2. The solution was stirred at room
temperature until the reaction was complete (ca. 24 h). The
progress of the reaction could easily be followed by NMR
spectroscopy. The mixture was then evaporated, and the
residue was extracted with toluene, filtered, and crystallized
from toluene to afford 0.277 g (0.46 mmol, 46%) of (CabC,N)2-
Hg (6). Anal. Calcd: C, 19.98; H, 6.04; N, 4.66. Found: C,
Su p p or tin g In for m a tion Ava ila ble: Tables describing
the X-ray analysis (data collection and analysis), crystal data,
atomic coordinates, anisotropic thermal parameters, bond
lengths and angles, and least-squares planes for 3a ,b, 6, and
7. This material is available free of charge via the Internet at
http://pubs.acs.org.
OM990935S
(25) (a) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, A46, 467.
(b) Sheldrick, G. M. SHELXL, Program for Crystal Structure Refine-
ment; University of Go¨ttingen, Go¨ttingen, Germany, 1997.