Synthesis and structural comparison of triaryl(sulfonylimino)pnictoranes

Article abstract of DOI:10.1021/ic0110575

Triarylphosphanes 1 (Ar₃P; Ar = Ph, 4-MeC₆H₄), triphenylarsane (2), and triarylstibanes 3 (Ar₃Sb; Ar = 2-MeC₆H₄, 2-MeOC₆H₄) reacted with trifluoromethanesulfonamide (7a) in the presence of equimolar diethyl azodicarboxylate to afford the corresponding triaryl(sulfonylimino)pnictoranes [Ar₃M=NSO₂CF₃; 8 (M = P), 9 (M = As), 10 (M = Sb)]. The Kirsanov-type reaction of triarylantimony dichlorides 5 (Ar₃SbCl₂; Ar = 2-MeC₆H₄, 2-MeOC₆H₄) and triarylbismuth dichlorides 6 (Ar₃BiCl₂; Ar = 2-MeC₆H₄, 2-MeOC₆H₄, 2,4,6-Me₃C₆H₂) with sulfonamides 7 (H₂NSO₂R; R = CF₃, 4-MeC₆H₄, Me) in the presence of 2 equiv of potassium tert-butoxide yielded triaryl(sulfonylimino)-λ⁵-stibanes 10 and -bismuthanes 11, respectively. The ortho-substitution in aryl ligands of 10 and 11 has been found to bring about considerable kinetic stabilization of the reactive Sb=N and Bi=N bonds. A structural comparison was made for a series of triaryl(sulfonylimino)pnictoranes 8-11 by IR spectroscopy and X-ray crystallography. In the IR spectra of 9-11, SO₂ asymmetric stretching absorptions (ν_SO2) were observed at lower wavenumbers as compared to those of phosphorus counterparts 8. The difference in frequency (δν_SO2) from 8 increased progressively as the pnictogen element being utilized moved down the group 15 column on the periodic table. X-ray crystallographic analyses of eight of the triaryl(sulfonylimino)pnictoranes prepared confirmed the increasing single-bond character of the M=N bond, with the contribution from the canonical structure M⁺-N=S(O)-O^- increasing in importance in the order P < As < Sb < Bi. Among all triaryl(sulfonylimino)pnictoranes examined, only imino-λ⁵-bismuthanes 11 oxidized alcohols to carbonyl compounds.

Full text of DOI:10.1021/ic0110575

Inorg. Chem. 2002, 41, 1940−1948
Synthesis and Structural Comparison of
Triaryl(sulfonylimino)pnictoranes
Yoshihiro Matano,* Hazumi Nomura, and Hitomi Suzuki†
Department of Chemistry, Graduate School of Science, Kyoto UniVersity,
Sakyo-ku, Kyoto 606-8502, Japan
Received October 12, 2001
Triarylphosphanes 1 (Ar3P; Ar ) Ph, 4-MeC H ), triphenylarsane (2), and triarylstibanes 3 (Ar3Sb; Ar ) 2-MeC H ,
6
4
6 4
2-MeOC H ) reacted with trifluoromethanesulfonamide (7a) in the presence of equimolar diethyl azodicarboxylate
6
4
to afford the corresponding triaryl(sulfonylimino)pnictoranes [Ar3MdNSO CF ; 8 (M ) P), 9 (M ) As), 10 (M )
2
3
Sb)]. The Kirsanov-type reaction of triarylantimony dichlorides 5 (Ar3SbCl2; Ar ) 2-MeC H , 2-MeOC H ) and
6
4
6 4
triarylbismuth dichlorides 6 (Ar3BiCl2; Ar ) 2-MeC H , 2-MeOC H , 2,4,6-Me3C H ) with sulfonamides 7 (H NSO R;
6
4
6
4
6
2
2
2
R ) CF , 4-MeC H , Me) in the presence of 2 equiv of potassium tert-butoxide yielded triaryl(sulfonylimino)-λ5-
3
6 4
stibanes 10 and -bismuthanes 11, respectively. The ortho-substitution in aryl ligands of 10 and 11 has been found
to bring about considerable kinetic stabilization of the reactive SbdN and BidN bonds. A structural comparison
was made for a series of triaryl(sulfonylimino)pnictoranes 8−11 by IR spectroscopy and X-ray crystallography. In
the IR spectra of 9−11, SO asymmetric stretching absorptions (νSO2) were observed at lower wavenumbers as
2
compared to those of phosphorus counterparts 8. The difference in frequency (∆νSO2) from 8 increased progressively
as the pnictogen element being utilized moved down the group 15 column on the periodic table. X-ray crystallographic
analyses of eight of the triaryl(sulfonylimino)pnictoranes prepared confirmed the increasing single-bond character
+
of the MdN bond, with the contribution from the canonical structure M sNdS(O)sO- increasing in importance
in the order P < As < Sb < Bi. Among all triaryl(sulfonylimino)pnictoranes examined, only imino-λ5-bismuthanes 11
oxidized alcohols to carbonyl compounds.
Introduction
the PdN bond in imino-λ5-phosphanes on the basis of
experimental7,8 and theoretical studies.8c,9 Recent theoretical
studies on an imaginary imino-λ5-phosphane (H3PdNH) have
led to the conclusion that the electrostatic interaction, as well
as the n-σ* negative hyperconjugation,10 between the
phosphorus and nitrogen atoms is responsible for the PdN
bond shortening of imino-λ5-phosphane.11 To gain a sys-
tematic understanding of the nature of MdN bonds, however,
it would be more productive to compare the structure and
In recent decades, the chemistry of iminopnictoranes
(R3MdNR′; M ) P, As, Sb, Bi)1 has received considerable
attention due to the role of these compounds in reactions
that form a bond with nitrogen as well as the chemical
analogy with ylides (R3MdCR′R′′) and oxides (R3MdO).2
For instance, the aza-Wittig reaction based on imino λ5-
phosphanes has found a wide range of applications in organic
synthesis.3 Although the examples are yet limited in number,
the synthetic application of imino-λ5-arsanes,4 -stibanes,4k,5
and -bismuthanes4k,6 has also been a subject of recent studies.
A salient structural feature of the iminopnictoranes is the
nature of the MdN bonds. The vast majority of related
studies have been devoted to exploring the multiplicity of
(2) (a) Singh, G.; Zimmer, H. Organomet. Chem. ReV. 1967, 2, 279-
348. (b) Abel, E. W.; Mucklejohn, S. A. Phosphorus and Sulfur 1981,
9, 235-266. (c) Gololobov, Y. G.; Zhmurova, I. N.; Kasukhin, L. F.
Tetrahedron 1981, 37, 437-472. (d) Gololobov, Y. G.; Kasukhin, L.
F. Tetrahedron 1992, 48, 1353-1406. (e) Johnson, A. W. Ylides and
Imines of Phosphorus; Wiley: New York, 1993. (f) Lloyd, D.; Gosney,
I. In The Chemistry of Organic Arsenic, Antimony and Bismuth
Compounds; Patai, S., Ed.; Wiley: New York, 1994; Chapter 16, pp
657-693. (g) Matano, Y.; Suzuki, H. Bull. Chem. Soc. Jpn. 1996,
69, 2673-2681. (h) Matano, Y.; Ikegami, T. In Organobismuth
Chemistry; Suzuki, H., Matano, Y., Eds.; Elsevier: New York, 2001;
Chapter 3.6, pp 313-319 and references therein.
* To whom correspondence should be addressed. E-mail: matano@
kuchem.kyoto-u.ac.jp.
† Present address: Department of Chemistry, School of Science, Kwansei
Gakuin University, Sanda, 669-1337, Japan.
(1) Throughout this paper, the bond between a pnictogen and a nitrogen
atom in iminopnictoranes is depicted as MdN for simplicity.
(3) For a review, see: Molina, P.; Vilaplana, M. J. Synthesis 1994, 1197-
1218.
1940 Inorganic Chemistry, Vol. 41, No. 7, 2002
10.1021/ic0110575 CCC: $22.00 © 2002 American Chemical Society
Published on Web 03/01/2002

Triaryl(sulfonylimino)pnictoranes
reactivity of a series of iminopnictoranes bearing a common
substituent on the nitrogen atom.
of the intrinsic properties of the MdN bonds.13 These studies
have revealed that the single-bond character of the MdN
bond in iminopnictoranes increases as the atomic weight of
the pnictogen atom increases. However, the effects of other
N-substituents on the MdN bonding nature have not yet been
systematically examined, probably because of a lack of well-
characterized examples among known iminopnictoranes,
especially those derived from antimony and bismuth.
In 1997, Koketsu et al. reported a comparative study of
the structure and reactivity of a series of imaginary imino-
pnictoranes (H3MdNH; M ) P, As, Sb, Bi) on the basis of
ab initio molecular orbital calculations.12 Recently, we have
also carried out the first comparative study of the structure
and reactivity of a series of existing (acylimino)triarylpnic-
toranes (Ar3MdNCOR), for which the structural property
of the N-acyl group has been found to be strongly indicative
We have recently succeeded in determining the crystal
structures of the monomeric imino-λ5-stibanes that bear a
trifluoromethylsulfonyl group on the nitrogen atom.14 This
success led us to compare the structural properties of an
N-sulfonyliminopnictorane series, as we expected that the
N-sulfonyl groups would, like N-acyl groups, also reflect the
properties of the conjugated MdN bond and bring some
thermal stability to intrinsically thermolabile BidN bonds.
We report herein the results of synthesis and a structural
comparison of a series of triaryl(sulfonylimino)pnictoranes.
These results demonstrate that both the single-bond character
of the MdN bond and the contribution from canonical form
M+sNdS(O)sO- increase progressively as the pnictogen
element becomes heavier.
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Pinchuk, A. M.; Bespal’ko, G. K.; Khimchenko, T. V.; Kuplennik, Z.
I. Zh. Obshch. Khim. 1977, 47, 2153-2154. (d) Kuplennik, Z. I.;
Pinchuk, A. M. Zh. Obshch. Khim. 1979, 49, 155-160. (e) Kuplennik,
Z. I.; Belaya, Z. N.; Pinchuk, A. M. Zh. Obshch. Khim. 1981, 51,
2711-2715. (f) Kuplennik, Z. I.; Belaya, Z. N.; Pinchuk, A. M. Zh.
Obshch. Khim. 1984, 54, 462-463.
(6) (a) Wittig, G.; Hellwinkel, D. Chem. Ber. 1964, 97, 789-793. (b)
Suzuki, H.; Nakaya, C.; Matano, Y.; Ogawa, T. Chem. Lett. 1991,
105-108. (c) Pasenok, S. V.; Kirij, N. V.; Yagupolskii, Y. L.;
Naumann, D.; Tyrra, W. J. Fluorine Chem. 1993, 63, 179-183. (d)
Suzuki, H.; Ikegami, T. J. Chem. Res., Synop. 1996, 24-25. (e)
Ikegami, T.; Suzuki, H. Organometallics 1998, 17, 1013-1017. (f)
Matano, Y.; Nomura, H.; Shiro, M.; Suzuki, H. Organometallics 1999,
18, 2580-2582. (g) Matano, Y.; Nomura, H.; Suzuki, H. J. Organomet.
Chem. 2000, 611, 89-99.
(7) X-ray crystallographic analyses: (a) Cameron, T. S.; Prout, C. K. J.
Chem. Soc. C 1969, 2285-2288. (b) Adamson, G. W.; Bart, J. C. J.
J. Chem. Soc. A 1970, 1452-1456. (c) Cameron, A. F.; Hair, N. J.;
Morris, D. G. Acta Crystallogr. 1974, B30, 221-225. (d) Cameron,
T. S.; Mannan, K. Acta Crystallogr. 1977, B33, 443-446. (e)
Cameron, T. S.; Cordes, R. E.; Jackman, F. A. Acta Crystallogr. 1979,
B35, 980-982. (f) Bar, I.; Bernstein, J. Acta Crystallogr. 1980, B36,
1962-1964. (g) Chivers, T.; Cordes, A. W.; Oakley, R. T.; Swepston,
P. N. Inorg. Chem. 1981, 20, 2376-2380. (h) Nevstad, G. O.;
Rømming, C.; Songstad. J. Acta Chem. Scand. 1985, A39, 691-699.
(i) Zhu, S.; Xu, B.; Qin, C.; Xu, G. Inorg. Chem. 1997, 36, 4909-
4911. (j) Uchiyama, T.; Fujimoto, T.; Kakehi, A.; Yamamoto, I. J.
Chem. Soc., Perkin Trans. 1 1999, 1577-1580. See also Table 13.3
(p 415) in ref 2e.
(8) Spectroscopic studies: (a) Wiegra¨be, W.; Bock, H.; Lu¨ttke, W. Chem.
Ber. 1966, 99, 3737-3749. (b) Wiegra¨be, W.; Bock, H. Chem. Ber.
1968, 101, 1414-1427. (c) Albright, T. A.; Freeman, W. J.; Schweizer,
E. E. J. Org. Chem. 1976, 41, 2716-2720. (d) Astrup, E. E.; Bouzga,
A. M.; Ostoja Starzewski, K. A. J. Mol. Struct. 1979, 51, 51-59. (e)
Pomerantz, M.; Chou, W.-N.; Witczak, M. K.; Smith, C. G. J. Org.
Chem. 1987, 52, 159-163. (f) Chou, W.-N.; Pomerantz, M.; Witczak,
M. K. J. Org. Chem. 1990, 55, 716-721.
Experimental Section
General. All reactions with air-sensitive compounds were carried
out under an argon atmosphere. Melting points were determined
on a Yanagimoto hot-stage apparatus and are uncorrected. 1H and
13C NMR spectra were recorded on a Varian Gemini-200 or a JEOL
FX400 spectrometer using CDCl3 as a solvent unless otherwise
noted. Chemical shifts are reported as the relative value versus
tetramethylsilane. 19F NMR data were measured on a JEOL JNM-
LA500 spectrometer in CDCl3 using neat trifluoroacetic acid as an
external standard. IR spectra were observed as KBr pellets on a
Shimadzu FTIR-8100S or 8200A spectrometer. FABMS spectra
were measured on a JEOL JMS-HS100 spectrometer using m-
nitrophenyl octyl ether as a matrix. Elemental analyses were
performed at Microanalytical Laboratory of Kyoto University. CH2-
Cl2 and Et2O were distilled from calcium hydride and sodium
benzophenone ketyl, respectively, before use. Pentane, hexane,
CHCl3, and CDCl3 were distilled from CaH2 and stored over 4 Å
molecular sieves.
Triarylstibanes 3a,b were prepared from SbCl3 and the corre-
sponding Grignard reagents.15 Triarylantimony dichlorides 5 were
prepared from 3a,b and sulfuryl chloride. Triarylbismuth dichlorides
613 were obtained by the reaction of the corresponding triarylbis-
muthanes with sulfuryl chloride according to Barton’s procedure.16
Other reagents were used as commercially received.
Triarylstibanes, 3a: 1H NMR δ 2.48 (s, 9H), 6.98-7.05 (m,
6H), 7.24-7.29 (m, 6H). 3b: 1H NMR δ 3.76 (s, 9H), 6.82 (dt,
3H, J ) 1.0, 7.1 Hz), 6.85-6.90 (m, 6H), 7.31 (ddd, 3H, J ) 7.2,
7.1, 2.0 Hz).
(9) (a) Gonbeau, D.; Pfister-Guillouzo, G.; Mazie`res, M.-R.; Sanchez, M.
Can. J. Chem. 1985, 63, 3242-3248. (b) Nguyen, M. T.; Hegarty, A.
F. J. Chem. Soc., Perkin Trans. 2 1987, 47-54. (c) Molina, P.;
Alajar´ın, M.; Lo´pez-Leonardo, C.; Claramunt, R. M.; Foces-Foces,
M. de la C.; Herna´ndez-Cano, F.; Catala´n, J.; De Paz, J. L. G.; Elguero,
J. J. Am. Chem. Soc. 1989, 111, 355-363. (d) Sudhakar, P. V.;
Lammertsma, K. J. Am. Chem. Soc. 1991, 113, 1899-1906.
(10) Reed, A. E.; Schleyer, P. v. R. J. Am. Chem. Soc. 1990, 112, 1434-
1445.
(11) The pπ-dπ orbital interaction has become a classical means of
explaining the PdX bond-shortening (X ) C, N, or O). For example,
see: Gilheany, D. G. Chem. ReV. 1994, 94, 1339-1374.
(12) Koketsu, J.; Ninomiya, Y.; Suzuki, Y.; Koga, N. Inorg. Chem. 1997,
36, 694-702.
Triarylantimony Dichlorides, 5a: mp 234-236 °C; 1H NMR
δ 2.69 (s, 9H), 7.35-7.39 (m, 6H), 7.44-7.48 (m, 3H), 7.90 (d,
(13) Matano, Y.; Nomura, H.; Suzuki, H.; Shiro, M.; Nakano, H. J. Am.
Chem. Soc. 2001, 123, 10954-10965.
(14) Matano, Y.; Nomura, H.; Suzuki, H. Inorg. Chem. 2000, 39, 1340-
1341.
(15) Levason, W.; Sheikh, B. J. Organomet. Chem. 1981, 208, 1-9.
(16) Barton, D. H. R.; Bhatnagar, N. Y.; Finet, J.-P.; Motherwell, W. B.
Tetrahedron 1986, 42, 3111-3122.
Inorganic Chemistry, Vol. 41, No. 7, 2002 1941

Matano et al.
3H, J ) 7.6 Hz). Anal. Calcd for C21H21Cl2Sb: C, 54.12; H, 4.54.
Found: C, 54.03; H, 4.56. 5b: mp 231-238 °C; 1H NMR δ 3.82
(s, 9H), 7.04-7.18 (m, 6H), 7.46-7.55 (m, 3H), 7.88 (dd, 3H, J
) 7.7, 1.5 Hz). Anal. Calcd for C21H21Cl2O3Sb: C, 49.07; H, 4.12.
Found: C, 48.54; H, 3.97.
mL) at -50 °C. The mixture was allowed to gradually warm to
room temperature with stirring. The insoluble solid was filtered
off through Celite, and the filtrate was concentrated under reduced
pressure to leave an oily residue, which was crystallized from CH2-
Cl2/hexane to give triaryl(sulfonylimino)-λ5-bismuthane 11. Com-
pounds 10 were similarly obtained from triarylantimony dichlorides
5.
Synthesis of Triaryl(sulfonylimino)-λ5-phosphanes 8, -arsane
9, and -stibanes 10 by Redox Condensation17 (Method A).
Diethyl azodicarboxylate (40% in toluene; 0.5 mL, ∼1.1 mmol)
was added to a mixture of triarylphosphane 1 (1.0 mmol), amide
7a (1.0 mmol), and Et2O (10 mL) at 0 °C. The resulting mixture
was allowed to gradually warm to room temperature with stirring.
After 12 h, the solvent was removed under reduced pressure to
leave a solid that was then washed with Et2O and recrystallized
from CH2Cl2/hexane to yield triaryl(sulfonylimino)-λ5-phosphane
8. Imino-λ5-arsane 9 and imino-λ5-stibanes 10 were similarly
prepared from 2 and 3, respectively.
Tris(2-methylphenyl)[(trifluoromethanesulfonyl)imino]-λ5-
bismuthane, 11a: mp 131-138 °C; 1H NMR δ 2.49 (s, 9H), 7.45-
7.54 (m, 9H), 7.90 (d, 3H, J ) 7.8 Hz); 13C{1H} NMR δ 24.4,
129.2, 132.3, 133.1, 135.0, 143.4, 146.9; 19F NMR δ 0.046; IR ν
1586, 1559, 1464, 1453, 1420, 1387, 1279 (SO2, as), 1202, 1171,
1157, 1125, 992, 795, 762, 752, 642, 623, 610, 569, 515, 428 cm-1
;
FABMS m/z 630 ([M + H]+). Anal. Calcd for C22H21BiF3NO2S:
C, 41.98; H, 3.36; N, 2.23. Found: C, 41.97; H, 3.26; N, 2.15.
Tris(2-methoxyphenyl)[(trifluoromethanesulfonyl)imino]-λ5-
Triphenyl[(trifluoromethanesulfonyl)imino]-λ5-phosphane,
1
bismuthane, 11b: mp 137-151 °C (decomp); H NMR δ 3.69
1
8a: mp 165-167 °C (lit.,18 168-169 °C); H NMR δ 7.53-7.57
(s, 9H), 7.10-7.25 (m, 6H), 7.48-7.56 (m, 3H), 8.01 (dd, 3H, J
) 7.6, 1.3 Hz); 13C{1H} NMR δ 56.1, 112.0, 123.9, 133.2, 135.0,
136.9, 159.8; 19F NMR δ -0.259; IR ν 1590, 1563, 1472, 1435,
1294, 1279, 1269 (SO2, as), 1242, 1206, 1159, 1121, 1046, 1013,
994, 787, 766, 758, 637, 612, 567, 517, 477, 430 cm-1; FABMS
m/z 678 ([M + H]+). Anal. Calcd for C22H21BiF3NO5S: C, 39.00;
H, 3.12; N, 2.07. Found: C, 38.93; H, 3.07; N, 2.09.
3
(m, 6H), 7.67 (t, 3H, J ) 7.4 Hz), 7.77 (dd, 6H, JPH ) 13.4 Hz,
3JHH ) 8.2 Hz); IR ν 1590, 1485, 1437, 1320 (SO2, as), 1246, 1211,
1171, 1157, 1113, 1096, 1028, 999, 795, 752, 741, 723, 693, 613,
581, 558, 544, 531, 511, 502, 434 cm-1
.
Tris(4-methylphenyl)[(trifluoromethanesulfonyl)imino]-λ5-
1
phosphane, 8b: mp 209-210 °C; H NMR δ 2.43 (s, 9H), 7.32
(dd, 6H, 3JHH ) 8.3 Hz, 4JPH ) 3.7 Hz), 7.62 (dd, 6H, 3JPH ) 13.1
[(Trifluoromethanesulfonyl)imino]tris(2,4,6-trimethylphenyl)-
3
1
Hz, JHH ) 8.3 Hz); 13C{1H} NMR δ 21.7, 123.1 (d, JPC ) 108
1
λ5-bismuthane, 11c: mp 173-175 °C; H NMR δ 2.29 (s, 9H),
2
3
Hz), 129.7 (d, JPC ) 13.7 Hz), 133.0 (d, JPC ) 11.4 Hz), 144.3
(d, 4JPC ) 2.8 Hz); IR ν 1601, 1563, 1501, 1449, 1402, 1381, 1316
(SO2, as), 1283, 1233, 1204, 1190, 1175, 1165, 1113, 1094, 1040,
1022, 845, 810, 783, 750, 710, 668, 660, 625, 604, 575, 554, 534,
517, 511, 504, 459, 451 cm-1. Anal. Calcd for C22H21F3NO2PS:
C, 58.53; H, 4.69; N, 3.10. Found: C, 58.53; H, 4.77; N, 3.12.
Triphenyl[(trifluoromethanesulfonyl)imino]-λ5-arsane, 9: mp
183-185 °C; 1H NMR δ 7.56-7.60 (m, 6H), 7.68 (t, 3H, J ) 7.4
Hz), 7.77 (d, 6H, J ) 7.8 Hz); IR ν 1578, 1483, 1443, 1306 (SO2,
as), 1213, 1192, 1175, 1163, 1140, 1086, 1019, 997, 758, 749, 741,
706, 687, 623, 610, 573, 521, 478, 463, 419 cm-1. Anal. Calcd for
C19H15AsF3NO2S: C, 50.34; H, 3.34; N, 3.09. Found: C, 50.12;
H, 3.45; N, 3.13.
2.58 (s, 18H), 7.08 (s, 6H); IR ν 1590, 1566, 1453, 1381, 1294,
1267 (SO2, as), 1198, 1163, 1113, 1028, 972, 941, 853, 687, 631,
612, 581, 565, 538, 511, 492 cm-1; FABMS m/z 714 ([M + H]+).
Tris(2-methylphenyl)(tosylimino)-λ5-bismuthane, 11d: 1H NMR
δ 2.30 (s, 3H), 2.36 (s, 9H), 6.98 (d, 2H, J ) 8.0 Hz), 7.35-7.48
(m, 9H), 7.57 (d, 2H, J ) 8.0 Hz), 7.90-7.94 (m, 3H); 13C{1H}
NMR δ 21.3, 24.3, 125.9, 128.5, 128.8, 131.7, 132.5, 135.4, 139.5,
143.6, 144.8, 146.7; IR ν 1599, 1586, 1493, 1468, 1451, 1383,
1275, 1229 (SO2, as), 1204, 1161, 1117, 1076, 1024, 1007, 943,
820, 793, 756, 749, 735, 708, 664, 644, 625, 567, 546, 428 cm-1
FABMS m/z 652 ([M + H]+).
;
Tris(2-methoxyphenyl)(tosylimino)-λ5-bismuthane, 11e: mp
179-182 °C (decomp); 1H NMR δ 2.28 (s, 3H), 3.51 (s, 9H), 6.92-
7.02 (m, 5H), 7.13-7.20 (m, 3H), 7.41-7.50 (m, 3H), 7.57 (d,
2H, J ) 8.1 Hz), 8.04 (d, 3H, J ) 7.9 Hz); 13C{1H} NMR δ 21.2,
55.7, 111.5, 123.6, 126.0, 128.2, 132.6, 135.7, 136.8, 138.7, 146.2,
160.0; IR ν 1580, 1568, 1472, 1451, 1435, 1298, 1277, 1248 (SO2,
as), 1229, 1183, 1165, 1119, 1075, 1049, 1019, 947, 853, 824, 789,
762, 712, 662, 567, 548, 477, 434 cm-1; FABMS m/z 700 ([M +
H]+). Anal. Calcd for C28H28BiNO5S: C, 48.07; H, 4.03; N, 2.00.
Found: C, 48.35; H, 3.81; N, 2.06.
(Mesylimino)tris(2-methylphenyl)-λ5-bismuthane, 11f: mp
158-175 °C (decomp); 1H NMR δ 2.50 (s, 9H), 2.96 (s, 3H), 7.40-
7.49 (m, 9H), 7.92-7.96 (m, 3H); 13C{1H} NMR δ 24.4, 44.3,
129.0, 131.8, 132.6, 135.2, 143.4, 147.0; IR ν 1584, 1559, 1466,
1451, 1310, 1275, 1227 (SO2, as), 1204, 1163, 1088, 1003, 965,
953, 795, 783, 762, 750, 621, 527, 513, 428 cm-1; FABMS m/z
576 ([M + H]+). Anal. Calcd for C22H24BiNO2S: C, 45.92; H,
4.20; N, 2.43. Found: C, 45.06; H, 3.92; N, 2.41.
Tris(2-methylphenyl)[(trifluoromethanesulfonyl)imino]-λ5-
1
stibane, 10a: mp 168-170 °C; H NMR δ 2.48 (s, 9H), 7.38-
7.42 (m, 6H), 7.53-7.57 (m, 3H), 7.74 (d, 3H, J ) 7.6 Hz); 13C{1H}
NMR δ 23.9, 127.6, 127.9, 132.2, 133.3, 135.0, 144.0; IR ν 1578,
1472, 1456, 1393, 1287 (SO2, as), 1211, 1181, 1159, 1140, 1022,
797, 766, 749, 700, 654, 644, 619, 567, 546, 519, 484, 434, 410
cm-1. Anal. Calcd for C22H21F3NO2SSb: C, 48.73; H, 3.90; N,
2.58. Found: C, 48.22; H, 3.90; N, 2.40.
Tris(2-methoxyphenyl)[(trifluoromethanesulfonyl)imino]-λ5-
stibane, 10b: mp 165-168 °C; 1H NMR δ 3.68 (s, 9H), 6.99 (d,
3H, J ) 8.3 Hz), 7.10-7.19 (m, 3H), 7.52-7.61 (m, 3H), 7.73 (d,
3H, J ) 7.6 Hz); IR ν 1582, 1476, 1460, 1435, 1279 (SO2, as),
1246, 1208, 1175, 1127, 1053, 1013, 874, 851, 791, 756, 669, 615,
569, 517, 484, 438, 426, 403 cm-1. Anal. Calcd for C22H21F3NO5-
SSb: C, 44.77; H, 3.59; N, 2.37. Found: C, 44.54; H, 3.59; N,
2.38.
Synthesis of Triaryl(sulfonylimino)-λ5-stibanes 10 and -bis-
muthanes 11 by the Kirsanov-Type Reaction19 (Method B). KO-
t-Bu (998 mg, 8.89 mmol) was added to a mixture of triarylbismuth
dichloride 6 (4.00 mmol), amide 7 (4.05 mmol), and CH2Cl2 (80
(Mesylimino)tris(2-methoxyphenyl)-λ5-bismuthane, 11g: mp
127-135 °C (decomp); 1H NMR δ 2.92 (s, 3H), 3.65 (s, 9H), 7.07-
7.22 (m, 6H), 7.44-7.52 (m, 3H), 8.04 (d, 3H, J ) 7.3 Hz); 13C-
{1H} NMR δ 44.3, 55.9, 111.6, 123.8, 132.7, 135.6, 137.0, 160.0;
IR ν 1588, 1566, 1474, 1433, 1312, 1298, 1279, 1254, 1246 (SO2,
as), 1215, 1184, 1167, 1117, 1084, 1046, 1019, 980, 862, 787, 764,
750, 646, 627, 565, 527, 515, 477, 430 cm-1; FABMS m/z 624
(17) Bittner, S.; Assaf, Y.; Krief, P.; Pomerantz, M.; Ziemnicka, B. T.;
Smith, C. G. J. Org. Chem. 1985, 50, 1712-1718.
(18) Roy, A. K. J. Am. Chem. Soc. 1993, 115, 2598-2603.
(19) Kirsanov, A. V. Zh. Obshch. Khim. 1952, 22, 269-273.
1942 Inorganic Chemistry, Vol. 41, No. 7, 2002

Triaryl(sulfonylimino)pnictoranes
([M + H]+). Anal. Calcd for C22H24BiNO5S: C, 42.38; H, 3.88;
Scheme 1
N, 2.25. Found: C, 42.45; H, 3.69; N, 2.06.
Although spectroscopic data clearly supported a high state of
purity of 11c,d, we were not successful in obtaining satisfactory
analytical data of an accuracy within (0.4%.
Oxidation of Alcohols by Triaryl(sulfonylimino)-λ5-bismuth-
anes. A mixture of 11a (15.7 mg, 25 µmol), ethanol (7.2 µL, 0.12
mmol), and CDCl3 (0.5 mL) was heated at 40 °C, and the progress
1
of the reaction was monitored by H NMR using 9,10-dihydroan-
thracene (4.5 mg, 25 µmol) as an internal standard. After 36 h,
acetaldehyde (67%), toluene (85%), and diarylbismuth amide 12a
(76%) were formed. 2-Propanol was similarly oxidized by 11e to
give acetone (75%), toluene (91%), and 12b (73%). Compounds
8b, 9, and 10a did not oxidize these alcohols under the same
reaction conditions.
those of Creagh and Hubbel.26 All calculations were performed
using the teXsan27 crystallographic software package of Molecular
Structure Corporation. Further details of the crystal data are
provided in Supporting Information.
Bis(2-methylphenyl)bismuth trifluoromethanesulfonamide,
12a. 1H NMR δ 2.47 (s, 6H), 4.51 (br-s, 1H, NH), 7.39-7.59 (m,
6H), 8.28 (d, 2H, J ) 7.6 Hz); IR ν 3270, 1580, 1447, 1383, 1348
(SO2, as), 1269, 1219, 1186, 1138, 955, 793, 747, 613, 561, 505,
432 cm-1
.
Results and Discussion
Bis(2-methylphenyl)bismuth tosylamide, 12b. 1H NMR δ 2.39
(s, 3H), 2.40 (s, 6H), 4.37 (br-s, 1H, NH), 7.20 (d, 2H, J ) 8.0
Hz), 7.32-7.41 (m, 4H), 7.45 (d, 2H, J ) 7.2 Hz), 7.70 (d, 2H, J
) 8.0 Hz), 8.15 (d, 2H, J ) 7.2 Hz); IR ν 3290, 1599, 1578, 1495,
1447, 1398, 1310 (SO2, as), 1302, 1286, 1204, 1142, 1088, 1020,
914, 810, 750, 741, 667, 563, 544, 432; FABMS m/z 470 ([M -
Tol]+).
Synthesis. Triaryl(sulfonylimino)pnictoranes 8-11 were
prepared by two different methods (Scheme 1 and Table 1).
Triaryl(sulfonylimino)-λ5-phosphanes 8, -arsane 9, and
-stibanes 10 were prepared by the Bittner’s redox condensa-
tion reaction (method A).17 Treatment of triarylphosphanes
1a,b, triphenylarsane (2), and triarylstibanes 3a,b with
trifluoromethanesulfonamide (7a) in the presence of an
equimolar diethyl azodicarboxylate (DEADC) in Et2O af-
forded the corresponding triaryl(sulfonylimino)-λ5-phos-
phanes 8a,b,18 -arsane 9, and -stibanes 10a,b,14 respectively
(entries 1-5 in Table 1). With triphenylstibane (3c),
however, triphenylstibane oxide28 was obtained in place of
the expected triphenyl(sulfonylimino)-λ5-stibane 10c (entry
6).5a Presumably, the resulting stibonium salt or imino-λ5-
stibane 10c was readily hydrolyzed during the reaction. The
DEADC-promoted redox condensation between tris(2-me-
thylphenyl)bismuthane (4) and 7a did not take place at room
temperature even after 48 h, probably because of the low
nucleophilicity of a lone electron pair of 4 (entry 7).
Although spectroscopic data clearly supported a high state of
purity of 12a,b, we were not successful in obtaining satisfactory
analytical data of an accuracy within (0.4%.
X-ray Crystallographic Analysis of Triaryl(sulfonylimino)-
pnictoranes. Single crystals of 8a, 8b, 9, 10a, 10b, 11a, 11b, and
11e were grown from CH2Cl2/hexane or CH2Cl2/pentane at 4 °C.
Data were recorded on a Rigaku AFC7S diffractometer, with
graphite-monochromated Mo KR (λ ) 0.71069 Å) radiation, using
the ω-2θ scan technique. The intensities of three representative
reflections were measured after every 150 reflections. An empirical
absorption correction based on azimuthal scans of several reflections
was applied. The data were corrected for Lorentz and polarization
effects. The structures were solved by the Patterson methods20 (for
11a) or direct methods21 (for 8a, 8b, 9, 10a, 10b, 11b, and 11e)
and expanded using the Fourier techniques.22 The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were included
but not refined. Neutral atom scattering factors were taken from
Alternatively, triaryl(sulfonylimino)-λ5-stibanes 10a,b were
synthesized by a Kirsanov-type reaction (method B).19
Triarylantimony dichlorides 5a,b reacted with 7a in the
presence of 2.2 equiv of KO-t-Bu in CH2Cl2 to afford 10a,b
in 77-96% yields (entries 8,9). Triaryl(sulfonylimino)-λ5-
bismuthanes 11a-g were similarly obtained in 23-98%
yields from triarylbismuth dichlorides 6a-c and amides
7a-c (entries 11-17). However, triphenyl derivatives, Ph3-
Cromer and Waber.23 Anomalous dispersion effects were included
24
in Fcalcd
;
the values for ∆f ′ and ∆f ′′ were those of Creagh and
McAuley.25 The values for the mass-attenuation coefficients are
(20) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman,
W. P.; de Gelder, R.; Israel, R.; Smits, J. M. M. The DIRDIF-94
program system; Technical Report of the Crystallography Laboratory;
University of Nijmegen: The Netherlands, 1994.
(21) SIR92: Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, M.;
Giacovazzo, C.; Guagliardi, A.; Polidori, G. J. Appl. Crystallogr. 1994,
27, 435.
5a
6c
SbdNSO2CF3 (10c) and Ph3BidNSO2CF3 (11h), were
readily hydrolyzed during workup in air to give triphenyl-
stibane oxide together with trace amounts of µ-oxo-bridged
antimony(V) compound (Ph3SbNHSO2CF3)2O29 from the
(22) DIRDIF-94: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman,
W. P.; de Gelder, R.; Israel, R.; Smits, J. M. M. The DIRDIF-94
program system; Technical Report of the Crystallography Laboratory;
University of Nijmegen: The Netherlands, 1994.
(23) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
(24) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
(25) Creagh, D. C.; McAuley, W. J. International Tables for Crystal-
lography; Wilson, A. J. C., Ed.; Kluwer Academic Publishers: Boston,
1992; Vol. C, Table 4.2.6.8, pp 219-222.
(26) Creagh, D. C.; Hubbell, J. H. International Tables for Crystallography;
Wilson, A. J. C., Ed.; Kluwer Academic Publishers: Boston, 1992;
Vol. C, Table 4.2.4.3, pp 200-206.
(27) teXsan: Crystal Structure Analysis Package; Molecular Structure
Corporation: The Woodlands, TX, 1985, 1999.
(28) Bordner, J.; Doak, G. O.; Everett, T. S. J. Am. Chem. Soc. 1986, 108,
4206-4213.
(29) This compound was structurally determined by X-ray crystallography.
The bond parameters and crystal data are reported as a CIF file in the
Supporting Information.
Inorganic Chemistry, Vol. 41, No. 7, 2002 1943

Matano et al.
Table 1. Synthesis of Triaryl(sulfonylimino)pnictoranes
entry
Ar3M or Ar3MX2
H2NSO2R
methoda
iminopnictorane
yield/%
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Ph3P (1a)
p-Tol3P (1b)
Ph3As (2)
7a
7a
7a
7a
7a
7a
7a
7a
7a
7a
7a
7a
7a
7b
7b
7c
7c
7a
A
A
A
A
A
A
A
B
B
B
B
B
B
B
B
B
B
B
Ph3PdNSO2CF3 (8a)
p-Tol3PdNSO2CF3 (8b)
Ph3AsdNSO2CF3 (9)
o-Tol3SbdNSO2CF3 (10a)
o-Ans3SbdNSO2CF3 (10b)
Ph3SbdNSO2CF3 (10c)
no reaction
10a
10b
10c
o-Tol3BidNSO2CF3 (11a)
o-Ans3BidNSO2CF3 (11b)
Mes3BidNSO2CF3 (11c)
o-Tol3BidNSO2(p-Tol) (11d)
o-Ans3BidNSO2(p-Tol) (11e)
o-Tol3BidNSO2Me (11f)
o-Ans3BidNSO2Me (11g)
Ph3BidNSO2CF3 (11h)
46
92
70
90
88
b
o-Tol3Sb (3a)
o-Ans3Sb (3b)
Ph3Sb (3c)
o-Tol3Bi (4)
o-Tol3SbCl2 (5a)
o-Ans3SbCl2 (5b)
Ph3SbCl2 (5c)
o-Tol3BiCl2 (6a)
o-Ans3BiCl2 (6b)
Mes3BiCl2 (6c)
6a
96
77
b
98
92
84
96
65
80
23
b
6b
6a
6b
Ph3BiCl2 (6d)
a A: 7 (1.0 equiv), EtO2CNdNCO2Et (1.1 equiv), Et2O, 0 °C to r.t., 12 h. B: 7 (1.0 equiv), KO-t-Bu (2.2 equiv), CH2Cl2, -50 °C to r.t. b Not isolated.
Table 2. SO2 Asymmetric Stretching Bands of Triaryl(sulfonylimino)pnictoranesa
Ar3MdNSO2CF3
ν(∆νb)
Ar3MdNSO2(p-Tol)
ν(∆νb)
Ar3MdNSO2Me
ν(∆νb)
o-Tol3BidNTf (11a)
o-Ans3BidNTf (11b)
Mes3BidNTf (11c)
o-Tol3SbdNTf (10a)
o-Ans3SbdNTf (10b)
Ph3AsdNTf (9)
1279 (41)
1269 (51)
1267 (53)
1287 (33)
1279 (41)
1306 (14)
1316 (4)
o-Tol3BidNTs (11d)
o-Ans3BidNTs (11e)
1229 (41)
1248 (22)
o-Tol3BidNMs (11g)
o-Ans3BidNMs (11h)
1227 (28)
1246 (9)
Ph3SbdNTsc
Ph3AsdNTsd
Ph3PdNTse
1200 (70)
1250 (20)
1270 (0)
Ph3AsdNMsd
Ph3PdNMse
1255 (0)
1255 (0)
p-Tol3PdNTf (8b)
Ph3PdNTf (8a)
1320 (0)
a Reported in cm-1. Tf ) SO2CF3. Ts ) SO2(p-Tol). Ms ) SO2Me. b Difference in frequency from the respective triphenyl(sulfonylimino)-λ5-phosphanes
(8a, Ph3PdNTs, and Ph3PdNMs). c Shah, J. J. J. Tenn. Acad. Sci. 1976, 51, 130-134. d Taken from ref 4g. e Taken from ref 17.
Scheme 2
former and a polymeric triphenylbismuthane oxide30 from
the latter (entries 10 and 18). These results indicate that the
ortho-substituted aryl ligands can provide the moisture-
sensitive SbdN and BidN bonds with some kinetic stabi-
lization.31 Triaryl(sulfonylimino)pnictoranes 8-11 were iso-
lated as thermally stable solids that can be stored in a
refrigerator (at 4 °C) for over a month.
increasingly prominent as the pnictogen atom becomes
heavier. A similar trend was also observed for the N-tosyl
and N-mesyl derivatives derived from P, As, and Bi.
Therefore, the contribution of a canonical form Z would be
more significant than that of two others X and Y for heavy
triaryl(sulfonyl)iminopnictoranes (Scheme 2). Both the SO2
symmetric and S-N stretching bands overlapped with other
absorptions and could not be located.
A series of triaryl(sulfonylimino)pnictoranes, 8a, 8b, 9,
10a, 10b, 11a, 11b, and 11e, were characterized by X-ray
crystallography and their structures compared. ORTEP
diagrams are presented in Figures 1-8, selected bond
parameters are listed in Table 3, and crystal data are
summarized in Table 4.32 All iminopnictoranes were found
to exist in a monomeric form, and no intermolecular
interaction between the pnictogen atom and neighboring
molecules was apparently observed. Each pnictogen center
possesses a distorted tetrahedral geometry, to which one of
the sulfonyl oxygen atoms, O(1), coordinates weakly (vide
infra). The ortho-substituents in compounds 10 and 11 were
Structural Comparison. The structures of triaryl(sulfo-
1
nylimino)pnictoranes 8-11 were characterized by H and
13C NMR, IR, and FABMS spectroscopies as well as by
X-ray crystallography. In the IR spectra, the SO2 asymmetric
stretching absorptions (νSO2) of sulfonylimino-λ5-arsanes,
-stibanes, and -bismuthanes were observed at lower frequen-
cies than those of sulfonylimino-λ5-phosphanes (Table 2).
In a series of the N-trifluoromethanesulfonyl derivatives,
the differences in frequency (∆νSO2) from 8a increased
progressively in the order 9 < 10a,b < 11a-c, suggesting
that the single-bond character of the SdO bond becomes
(30) (a) Goel, R. G.; Prasad, H. S. J. Organomet. Chem. 1972, 36, 323-
332. (b) Goel, R. G.; Prasad, H. S. J. Organomet. Chem. 1973, 50,
129-134. (c) Suzuki, H.; Ikegami, T.; Matano, Y. Tetrahedron Lett.
1994, 35, 8197-8200. (d) Matano, Y.; Nomura, H. J. Am. Chem. Soc.
2001, 123, 6443-6444.
(31) Kinetic protection by ortho-substituted aryl groups has been employed
for the stabilization of highly reactive functionalities. For example,
see: (a) Yoshifuji, M.; Shima, I.; Inamoto, N.; Hirotsu, K.; Higuchi,
T. J. Am. Chem. Soc. 1981, 103, 4587-4589. (b) West, R.; Fink, M.
J.; Michl, J. Science 1981, 214, 1343-1344. (c) Cowley, A. H.;
Kilduff, J. E.; Newman, T. H.; Pakulski, M. J. Am. Chem. Soc. 1982,
104, 5820-5821. (d) Tokitoh, N.; Arai, Y.; Okazaki, R.; Nagase, S.
Science 1997, 277, 78-80. (e) Tokitoh, N.; Matsumoto, T.; Okazaki,
R. Bull. Chem. Soc. Jpn. 1999, 72, 1665-1684.
(32) After the previous communication (ref 14), the structures of imino-
λ5-stibanes 10a,b were re-solved at a recommended level of calcula-
tion, and the bond parameters of these compounds reported herein
are the revised ones.
1944 Inorganic Chemistry, Vol. 41, No. 7, 2002

Triaryl(sulfonylimino)pnictoranes
Figure 4. ORTEP diagram for 10a (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): Sb-C(1), 2.101(4); Sb-C(7), 2.106(4);
Sb-C(13), 2.114(4); C(1)-Sb-C(7), 108.8(2); C(1)-Sb-C(13), 106.3(2);
C(7)-Sb-C(13), 113.5(2); N-Sb-C(1), 100.5(2); N-Sb-C(7), 117.0(2);
N-Sb-C(13), 109.4(2).
Figure 1. ORTEP diagram for 8a (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): P-C(1), 1.793(2); P-C(7), 1.793(2);
P-C(13), 1.800(2); C(1)-P-C(7), 109.8(1); C(1)-P-C(13), 107.7(1);
C(7)-P-C(13), 107.9(1); N-P-C(1), 105.3(1); N-P-C(7), 109.8(1);
N-P-C(13), 116.2(1).
Figure 2. ORTEP diagram for 8b (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): P-C(1), 1.791(4); P-C(7), 1.796(4);
P-C(13), 1.794(4); C(1)-P-C(7), 107.1(2); C(1)-P-C(13), 108.0(2);
C(7)-P-C(13), 109.2(5); N-P-C(1), 104.6(2); N-P-C(7), 111.7(2);
N-P-C(13), 115.7(2).
Figure 5. ORTEP diagram for 10b (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): Sb-C(1), 2.098(2); Sb-C(7), 2.098(2);
Sb-C(13), 2.090(2); C(1)-Sb-C(7), 106.66(9); C(1)-Sb-C(13), 110.45(10);
C(7)-Sb-C(13), 113.16(9); N-Sb-C(1), 107.63(9); N-Sb-C(7), 107.24(9);
N-Sb-C(13), 111.41(8).
Figure 6. ORTEP diagram for 11a (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): Bi-C(1), 2.224(7); Bi-C(7), 2.245(7);
Bi-C(13), 2.224(7); C(1)-Bi-C(7), 111.9(3); C(1)-Bi-C(13), 106.3(3);
C(7)-Bi-C(13), 122.0(3); N-Bi-C(1), 96.4(3); N-Bi-C(7), 107.3(3);
N-Bi-C(13), 110.1(3).
Figure 3. ORTEP diagram for 9 (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): As-C(1), 1.898(8); As-C(7), 1.908(8);
As-C(13), 1.920(8); C(1)-As-C(7), 108.2(3); C(1)-As-C(13), 108.0(4);
C(7)-As-C(13), 109.6(4); N-As-C(1), 103.3(4); N-As-C(7), 111.4(4);
N-As-C(13), 115.8(4).
found to interact with the pnictogen center sterically or
electronically: In 10a and 11a, there is repulsive interaction
between the ortho-methyl groups and the pnictogen center,
whereas in 10b, 11b, and 11e there is attractive interaction
between the ortho-methoxy oxygen and pnictogen atoms.33
The observed MdN bond lengths primarily reflect the
orbital size of the respective pnictogen atoms34 and are within
the range of those of known iminopnictoranes.2e,4k,7,13,14,35,36
The MdN bond lengths of the N-sulfonyl derivatives exam-
ined here are slightly shorter than those of N-trichloroacetyl
Inorganic Chemistry, Vol. 41, No. 7, 2002 1945

Matano et al.
Å) observed for potassium phosphoramidate.38 Previous
discussion of the bonding nature of the P-N bond of
phosphorus(III) amides37 has suggested that the back-bonding
from the nitrogen to the phosphorus causes a P-N bond
shortening of 0.04-0.12 Å.39 Therefore, the PdN bonds of
8a,b are considered to possess considerable double-bond
character. The AsdN bond length of 1.776(7) Å in 9 is
shorter than typical As-N bond lengths (1.84-1.88 Å) of
arsenic(III) amides.37e,40 The SbdN bond lengths of 1.952(4)-
1.962(2) Å in imino-λ5-stibanes 10a,b are also shorter than
known Sb-N bond lengths (2.01-2.08 Å) of antimony(III)
amides.41 The BidN bond lengths of 2.073(8)-2.117(6) Å
in imino-λ5-bismuthanes 11a,b,e are slightly shorter than
known Bi-N bond lengths (2.165-2.20 Å) of bismuth(III)
amides.41c,d,42 Recently, Burford and co-workers have com-
pared the structures of a homologous series of bis(amido)-
diazadipnictetidines, [DipNMN(H)Dip]2 (M ) P, As, Sb, Bi;
Dip ) 2,6-diisopropylphenyl), from which the average M-N
bond lengths are estimated to be 1.709 Å for P-N, 1.867 Å
for As-N, 2.043 Å for Sb-N, and 2.165 Å for Bi-N.42c,43
Table 5 summarizes the ratios of the MdN bond lengths of
the triaryl[(trifluoromethylsulfonyl)imino]pnictoranes versus
the MsN bond lengths observed for [DipNMN(H)Dip]2. The
ratios increase steadily and approximate toward unity as the
pnictogen atoms become heavier, leading us to conclude that
the single-bond character of the MdN bond is more
prominent with heavier pnictogen elements.
Figure 7. ORTEP diagram for 11b (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): Bi-C(1), 2.212(8); Bi-C(7), 2.211(8);
Bi-C(13), 2.192(9); C(1)-Bi-C(7), 112.4(3); C(1)-Bi-C(13), 115.0(3);
C(7)-Bi-C(13), 107.0(3); N-Bi-C(1), 99.4(3); N-Bi-C(7), 104.7(4);
N-Bi-C(13), 117.9(3).
(37) Typical bond lengths are 1.68-1.69 Å for P-Nsp2 and 1.74-1.75 Å
for P-Nsp3 bonds. For example, see: (a) Rømming, C.; Songstad, J.
Acta Chem. Scand. 1978, A32, 689-699. (b) Thompson, M. L.;
Haltiwanger, R. C.; Norman, A. D. J. Chem. Soc., Chem. Commun.
1979, 647-648. (c) Scherer, O. J.; Andres, K.; Kru¨ger, C.; Tsay, Y.-
H.; Wolmerha¨user, G. Angew. Chem., Int. Ed. Engl. 1980, 19, 571-
572. (d) Thompson, M. L.; Tarassoli, A.; Haltiwanger, R. C.; Norman,
A. D. J. Am. Chem. Soc. 1981, 103, 6770-6772. (e) Atwood, J. L.;
Cowley, A. H.; Hunter, W. E.; Mehrotra, S. K. Inorg. Chem. 1982,
21, 1354-1356. (f) Chen, H.-J.; Haltiwanger, R. C.; Hill, T. G.;
Thompson, M. L.; Coons, D. E.; Norman, A. D. Inorg. Chem. 1985,
24, 4725-4730. (g) Cobbledick, R. E.; Einstein, F. W. B. Acta
Crystallogr. 1975, B31, 2731-2733.
(38) Cameron, T. S.; Chan, C.; Chute, W. J. Acta Crystallogr. 1980, B36,
2391-2393. The anion of potassium phosphoramidate (K[H3NO3P])
is considered to contain an “ideal” P-N single bond [1.800(4) Å],
where the nitrogen atom is sp3 hybridized with no lone pair of
electrons.
(39) The quaternization of the phosphorus atom through the P(III) to P(V)
conversion causes additional P-N bond-shortening.
Figure 8. ORTEP diagram for 11e (30% probability ellipsoids). Selected
bond lengths (Å) and angles (deg): Bi-C(1), 2.197(10); Bi-C(7), 2.188(9);
Bi-C(13), 2.211(10); C(1)-Bi-C(7), 110.0(4); C(1)-Bi-C(13), 106.5(4);
C(7)-Bi-C(13), 106.0(4); N-Bi-C(1), 109.1(4); N-Bi-C(7), 106.1(4);
N-Bi-C(13), 119.0(3).
derivatives, which constitute another homologous series of
iminopnictoranes characterized by X-ray crystallography.13
To estimate the multiplicity of the MdN bonds, the MdN
bond lengths are compared to the reported MsN bond
lengths of pnictogen(III) amides. The PdN bond lengths of
1.603(2)-1.609 (3) Å in 8a,b are much shorter than typical
P-N bond lengths (1.68-1.75 Å) observed for phosphorus-
(III) amides37 and the ideal P-N single-bond length (1.80
(40) Typical bond lengths are 1.84-1.85 Å for As-Nsp2 and 1.87-1.88
Å for As-Nsp3 bonds. For example, see: (a) Weiss, V. J.; Eisenhuth,
W. Z. Anorg. Allg. Chem. 1967, 350, 9-17. (b) Rømming, C.;
Songstad, J. Acta Chem. Scand. 1980, A34, 365-373.
(41) (a) Edwards, A. J.; Paver, M. A.; Raithby, P. R.; Russell, C. A.; Wright,
D. S. J. Chem. Soc., Dalton Trans. 1993, 2257-2258. (b) Edwards,
A. J.; Paver, M. A.; Rannie, M.-A.; Raithby, P. R.; Russell, C. A.;
Wright, D. S. J. Chem. Soc., Dalton Trans. 1994, 2963-2966. (c)
Burford, N.; Macdonald, C. L. B.; Robertson, K. N.; Cameron, T. S.
Inorg. Chem. 1996, 35, 4013-4016. (d) Mason, M. R.; Phulpagar, S.
S.; Mashuta, M. S.; Richardson, J. F. Inorg. Chem. 2000, 39, 3931-
3933. The values in parentheses are averaged.
(42) (a) Clegg, W.; Compton, N. A.; Errington, R. J.; Norman, N. C.;
Wishart, N. Polyhedron 1989, 8, 1579-1580. (b) Clegg, W.; Compton,
N. A.; Errington, R. J.; Fisher, G. A.; Green, M. E.; Hockless, D. C.
R.; Norman, N. C. Inorg. Chem. 1991, 30, 4680-4682. (c) Wirringa,
U.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Inorg. Chem.
1994, 33, 4607-4608. The values in parentheses are averaged.
(43) Burford, N.; Cameron, T. S.; Lam, K.-C.; LeBlanc, D. J.; Macdonald,
C. L. B.; Phillips, A. D.; Rheingold, A. L.; Stark, L.; Walsh, D. Can.
J. Chem. 2001, 79, 342-348.
(33) The ortho-methyl groups of 10a and 11a lean ∼3-5° away from the
pnictogen center, whereas the ortho-methoxy groups of 10b, 11b, and
11e lean ∼5-6° toward the pnictogen center.
(34) Emsley, J. The Elements, 3rd ed.; Oxford University Press: Oxford,
U.K., 1998. Covalent radii: N, 0.70 Å; P, 1.10 Å; As, 1.21 Å; Sb,
1.41 Å; Bi, 1.52 Å; O, 0.66 Å. van der Waals radii: P, 1.90 Å; As,
2.00 Å; Sb, 2.20 Å; Bi, 2.40 Å; O, 1.40 Å.
(35) Imino-λ5-arsanes: (a) Roesky, H. W.; Witt, M.; Clegg, W.; Isenberg,
W.; Noltemeyer, M.; Sheldrick, G. M. Angew. Chem., Int. Ed. Engl.
1980, 19, 943-944. (b) Witt, M.; Roesky, H. W.; Noltemeyer, M.;
Clegg, W.; Schmidt, M.; Sheldrick, G. M. Angew. Chem., Int. Ed.
Engl. 1981, 20, 974-975. (c) Bailey, K.; Gosney, I.; Gould, R. O.;
Lloyd, D.; Taylor, P. J. Chem. Res., Synop. 1988, 386-387. (d)
Kokorev, G. I.; Litvinov, I. A.; Musin, R. Z.; Naumov, V. A. Zh.
Obshch. Khim. 1991, 61, 2713-2721. (e) Mai, H.-J.; Weller, F.;
Dehnicke, K.; Maichle-Mo¨ssmer, C.; Stra¨hle, J. Z. Anorg. Allg. Chem.
1994, 620, 851-855. See also ref 7i.
(36) A dimeric imino-λ5-stibane: Edwards, A. J.; Paver, M. A.; Pearson,
P.; Raithby, P. R.; Rennie, M.-A.; Russell, C. A.; Wright, D. S. J.
Organomet. Chem. 1995, 503, C29-C31.
1946 Inorganic Chemistry, Vol. 41, No. 7, 2002

Triaryl(sulfonylimino)pnictoranes
Table 3. Selected Bond Parameters of Triaryl(sulfonylimino)pnictoranes
8a
8b
9
10a
10b
11a
11b
11e
Bond Lengths (Å)
1.952(4)
M-N
1.603(2)
1.536(2)
1.423(2)
1.426(2)
3.216(2)
1.609(3)
1.548(3)
1.427(3)
1.418(3)
3.137(3)
1.776(7)
1.557(7)
1.439(6)
1.422(6)
3.038(6)
1.962(2)
1.535(2)
1.445(2)
1.436(2)
3.112(2)
2.117(6)
1.532(7)
1.433(7)
1.454(7)
3.285(7)
2.096(7)
1.516(7)
1.444(6)
1.450(7)
3.210(7)
2.073(8)
1.574(8)
1.463(9)
1.451(8)
3.067(8)
N-S
1.535(4)
1.445(4)
1.431(4)
3.259(4)
S-O(1)
S-O(2)
M‚‚‚O(1)
Bond Angles (deg)
122.9(2)
M-N-S
N-S-O(1)
N-S-O(2)
131.7(1)
115.4(1)
111.7(1)
127.1(2)
115.7(2)
112.0(2)
118.9(4)
115.1(4)
111.8(4)
117.3(1)
116.1(1)
112.3(1)
118.6(4)
117.2(4)
110.6(4)
117.6(4)
117.5(4)
112.6(4)
112.1(5)
113.8(5)
108.0(5)
116.0(2)
113.2(3)
Torsion Angles (deg)
10.3(4)
M-N-S-O(1)
-4.2(3)
2.8(4)
-0.9(7)
-9.6(2)
-16.9(7)
5.5(7)
-22.9(7)
Table 4. Crystal Data for Triaryl(sulfonylimino)pnictoranes
8a
8b
9
10a
10b
11a
11b
11e
empirical
formula
fw
C19H15F3-
NO2PS
409.36
C22H21F3-
NO2PS
451.44
C19H15AsF3-
NO2S
453.31
C22H21F3-
NO2SSb
542.22
C22H21F3-
NO5SSb
590.22
C22H21BiF3-
NO2S
629.45
C22H21BiF3-
NO5S
677.45
C28H28Bi-
NO5S
699.57
cryst
0.38 × 0.20 × 0.50 × 0.24 × 0.12 × 0.12 ×
0.40 × 0.10 × 0.30 × 0.10 × 0.10 × 0.10 × 0.20 × 0.19 × 0.45 × 0.15 ×
dimensions
0.20
0.10
0.08
0.10
0.10
0.20
0.10
0.10
(mm3)
cryst syst
a (Å)
triclinic
10.610(1)
11.414(1)
8.6814(5)
92.255(8)
100.704(7)
114.343(9)
933.2(2)
P1h
monoclinic
10.419(2)
21.244(2)
10.697(2)
monoclinic
11.085(5)
14.494(3)
24.257(2)
monoclinic
11.285(2)
15.234(3)
13.410(2)
triclinic
10.955(2)
14.268(2)
9.055(3)
100.29(2)
110.43(2)
107.50(1)
1199.5(6)
P1h
triclinic
10.507(1)
12.553(1)
9.377(1)
92.361(9)
108.031(8)
74.032(7)
1129.3(2)
P1h
monoclinic
11.403(2)
17.981(2)
11.777(2)
monoclinic
8.757(4)
14.985(8)
20.761(4)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z
112.56(1)
98.94(2)
103.10(1)
94.63(1)
96.93(3)
2186.5(7)
P21/n
4
3850(1)
C2/c
8
2245.3(7)
P21/n
4
2406.8(5)
P21/n
4
2704(1)
P21/n
4
2
2
2
D
calcd (g cm-3
)
1.457
1.371
1.564
(Mo KR,
0.71069)
19.16
1.604
1.634
1.851
1.869
1.718
radiation
(λ, Å)
(Mo KR,
0.71069)
3.02
(Mo KR,
0.71069)
2.65
(Mo KR,
0.71069)
13.62
(Mo KR,
0.71069)
12.91
(Mo KR,
0.71069)
79.26
(Mo KR,
0.71069)
74.55
(Mo KR,
0.71069)
66.22
µ (Mo KR)
(cm-1
)
temp (°C)
2θmax (deg)
23 ( 1
55.0
23 ( 1
55.0
26 ( 1
55.0
25 ( 1
55.0
26 ( 1
55.0
22 ( 1
54.8
21 ( 1
55.0
23 ( 1
55.0
no. reflns measd
total
4524
5282
4664
5406
5869
5433
5764
6869
unique
4519
5210
4634
5353
5521
5122
5701
6560
no. reflns
4290
5019
3437
5153
5521
5122
5701
6212
(all, 2θ <
55.00°)
244
0.043, 0.147
1.06
(all, 2θ <
54.98°)
271
0.063, 0.216
1.04
(I > 0.00σ(I),
2θ < 55.02°)
244
0.057, 0.177
0.81
(all, 2θ <
54.99°)
272
0.040, 0.140
0.85
(all, 2θ <
54.99°)
299
0.027, 0.086
1.01
(all, 2θ <
54.85°)
272
0.045, 0.135
1.10
(all, 2θ <
54.98°)
298
0.048, 0.150
0.90
(all, 2θ <
55.00°)
325
0.053, 0.176
1.12
no. variables
R1, Rw
GOF
double-bond length (1.40 Å).46 Among N-trifluoromethyl-
sulfonyl derivatives, 10a,b and 11a,b possess longer SdO
and shorter NsS bonds compared to 8a,b and 9, indicating
the increased contribution of canonical form Z to the heavier
(sulfonylimino)pnictoranes, in accordance with the IR data
(Scheme 2).
Table 5. MdN/MsN Bond Length Ratios
M
MdN/Å
MsN/Åa
MdN/MsN
P (8a,b)
As (9)
Sb (10a,b)
Bi (11a,b)
1.603-1.609
1.776
1.952-1.962
2.096-2.117
1.709
1.867
2.043
2.165
0.938-0.941
0.951
0.955-0.960
0.968-0.978
a Averaged MsN bond lengths of [DipNMN(H)Dip]2, taken from ref
The MdN and SsN bond lengths are also dependent on
the structure of the sulfonyl group. The N-trifluoromethyl-
sulfonyl derivatives possess slightly longer MdN bonds
compared to those of the N-tosyl derivatives; the MdN bonds
of 8a [1.603(2) Å], 9 [1.776(7) Å] and 11b [2.096(7) Å] are
all longer than those of Ph3PdNTs [1.579(4) Å],7c Ph3Asd
NTs [1.755(3) Å],35e and 11e [2.073(8) Å]. In contrast, the
42c and 43.
The bonding nature of the MsNsSO2 linkage is also
noteworthy. All observed NsS bond lengths are in the range
1.516(7)-1.574(8) Å. They are close to that [1.590(2) Å]
of Chloramine-T44 but much shorter than the ideal NsS
single-bond length (1.76 Å) observed for sulfamic acid
-
(H3N+sSO3 ).45 In contrast, the SdO bond lengths of 1.418-
(3)-1.463(9) Å are somewhat longer than the typical SdO
(45) (a) Sass, R. L. Acta Crystallogr. 1960, 13, 320-324. (b) Osaki, K.;
Tadokoro, H.; Nitta, I. Bull. Chem. Soc. Jpn. 1955, 28, 524-528.
(46) Gillespie, R. J.; Robinson, E. A. Can. J. Chem. 1963, 41, 2074-
2085.
(44) Olmstead, M. M.; Power, P. P. Inorg. Chem. 1986, 25, 4057-4058.
Inorganic Chemistry, Vol. 41, No. 7, 2002 1947

Matano et al.
atom.48 The observed reactivity of 11a,d stands in marked
contrast to that of imino-λ5-phosphane 8b, -arsane 9, and
-stibane 10a, which did not oxidize these alcohols under the
employed conditions (in CDCl3, 40 °C, 36-70 h).
Scheme 3
CDCl3
11a + EtOH 40 °C, 36 h8
o-Tol BiNHSO CF
MeCHO TolH
+
+
(1)
(2)
2
2
3
NsS bond lengths of 8a [1.536(2) Å], 9 [1.557(7) Å], and
11b [1.516(7) Å] are slightly shorter than those of Ph3Pd
NTs [1.586(4) Å],7c Ph3AsdNTs [1.572(3) Å],35e and 11e
[1.574(8) Å]. These findings may be interpreted by the strong
electron-withdrawing ability of the trifluoromethyl group on
the sulfur atom, enhancing both the single-bond character
of the MdN bond and the double-bond character of the Ns
S bond.47
All intramolecular M‚‚‚O(1) distances are much longer
than the sum of the covalent radii (1.76 Å for PsO; 1.87 Å
for AssO; 2.07 Å for SbsO; 2.18 Å for Bi-O) but are
clearly shorter than the sum of the van der Waals radii (3.30
Å for P‚‚‚O; 3.40 Å for As‚‚‚O; 3.60 Å for Sb‚‚‚O; 3.80 Å
for Bi‚‚‚O).34 A comparison of the observed M‚‚‚O(1)
distances with these values allows us to conclude that the
electrostatic interaction between the negatively charged
sulfonyl oxygen O(1) and the positively charged pnictogen
atoms would become more important in the order P < As
< Sb < Bi (Scheme 3).
Reactions. To compare the oxidizing ability of 8b, 9, 10a,
11a, and 11d, these compounds were treated with excess of
an alcohol in CDCl3. Imino-λ5-bismuthanes 11a,d oxidized
ethanol to acetaldehyde and 2-propanol to acetone, respec-
tively (eqs 1, 2). In these oxidations, toluene and bis(2-
methylphenyl)bismuth amides 12a,b were formed as byprod-
ucts, indicating that the R-hydrogen is abstracted from the
substrate by the tolyl group originally attached to the bismuth
(67%)
(85%)
12a (76%)
CDCl3
11d + i-PrOH reflux, 2 h8
Me CO
(75%)
o-Tol BiNHSO (p-Tol)
TolH
(91%)
+
+
2
2
2
12b (73%)
Summary
A series of triaryl(sulfonylimino)pnictoranes Ar3MdNSO2R
(M ) P, As, Sb, Bi) were prepared, and their structures were
elucidated by X-ray crystallography. The ortho-substitution
in aryl ligands has been found to provide kinetic stabilization
to the reactive SbdN and BidN bonds. The observed X-ray
structures clearly show the increased single-bond character
of the MdN bonds and the increased contribution of a
canonical form M+sNdS(O)sO- as the central pnictogen
element becomes heavier. Of several iminopnictoranes
examined, only triaryl(sulfonylimino)-λ5-bismuthane 11 could
oxidize alcohols to carbonyl compounds.
Acknowledgment. This work was supported by Grants-
in-Aid (1120224 and 12640516) from the Ministry of
Education, Science, Sports and Culture of Japan. We thank
Dr. Masamichi Ogasawara for 19F NMR measurement.
Supporting Information Available: CIF files for the crystal
structures of 8a, 8b, 9, 10a, 10b, 11a, 11b, 11e and (Ph3SbNHSO2-
CF3)2O. These materials are available free of charge via the Internet
at http://pubs.acs.org.
IC0110575
(47) Because of the inductive (-Iσ) effect of the trifluoromethyl group,
the canonical structure W may contribute to some extent to the actual
bonding state of the N-trifluoromethylsulfonyl derivatives.
(48) Bi(V)-alkoxo intermediates were proposed by Barton et al. in the
oxidation of alcohols by organobismuth(V) compounds. (a) Barton,
D. H. R.; Kitchin, J. P.; Lester, D. J.; Motherwell, W. B.; Papoula,
M. T. B. Tetrahedron 1981, 37 (Supplement 9), 73-79. (b) Barton,
D. H. R.; Lester, D. J.; Motherwell, W. B.; Papoula, M. T. B. J. Chem.
Soc., Chem. Commun. 1980, 246-247.
1948 Inorganic Chemistry, Vol. 41, No. 7, 2002