The synthesis of [{n-Bu2Sn(S2N2)}2] and its use in the preparation of organometallic iridium sulfur nitrogen complexes

Article abstract of DOI:10.1139/v02-085

The addition of [n-Bu₂SnCl₂] to a solution of [S₄N₃][Cl] in liquid ammonia gave after extraction of the dry reaction mixture the new tin disulfur dinitrido compound [{n-Bu₂Sn(S₂N₂)}₂] (1). Reaction of [{n-Bu₂Sn(S₂N₂)}₂] (1) with the pentamethylcyclopentadienyl (Cp*) iridium derivatives [{IrCl(μ-Cl)(η⁵-C₅Me₅)}₂] or [μ⁵-C₅Me₅)IrCl₂(PPh ₃)] gave different products, which were dependent on the reactant ratios. A 1:1 reaction between 1 and [{IrCl(μ-Cl)(η⁵-C₅Me₅}₂] gave only [η⁵-C₅Me₅)Ir(S₂N ₂)] (2) in moderate yield; the same product in higher yield was obtained from a 2:1 reaction between 1 and [(η⁵-C₅Me₅IrCl₂(PPh ₃]. Reaction of 1 and [ζ⁵-C₅Me₅)₂IrCl₂ (PPh₃)] (1:1 molar ratio) in the presence of NH₄[PF₆] gave the unusual bimetallic species [η⁵-C₅Me₅IrCl(PPh₃)S ₂N₂)Ir(η⁵-C₅Me₅] [PF₆] (3). The) X-ray crystal structures of 1, 2, and 3 are reported.

Full text of DOI:10.1139/v02-085

1481
The synthesis of [{n-Bu2Sn(S2N2)}2] and its use in
the preparation of organometallic iridium sulfur
nitrogen complexes
Stephen M. Aucott, Alexandra M.Z. Slawin, and J. Derek Woollins
Abstract: The addition of [n-Bu2SnCl2] to a solution of [S4N3][Cl] in liquid ammonia gave after extraction of the dry
reaction mixture the new tin disulfur dinitrido compound [{n-Bu2Sn(S2N2)}2] (1). Reaction of [{n-Bu2Sn(S2N2)}2] (1)
with the pentamethylcyclopentadienyl (Cp*) iridium derivatives [{IrCl(µ-Cl)(η5-C5Me5)}2] or [(η5-C5Me5)IrCl2(PPh3)]
gave different products, which were dependent on the reactant ratios. A 1:1 reaction between 1 and [{IrCl(µ-Cl)(η5-
C5Me5)}2] gave only [(η5-C5Me5)Ir(S2N2)] (2) in moderate yield; the same product in higher yield was obtained from a
2:1 reaction between 1 and [(η5-C5Me5)IrCl2(PPh3)]. Reaction of 1 and [(η5-C5Me5)2IrCl2(PPh3)] (1:1 molar ratio) in
the presence of NH4[PF6] gave the unusual bimetallic species [(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-C5Me5)][PF6] (3). The
X-ray crystal structures of 1, 2, and 3 are reported.
Key words: liquid ammonia, tin sulfur–nitrogen reagent, metathesis, sulfur–nitrogen metallacycle, iridium complexes.
Résumé : L’addition du [n-Bu2SnCl2] à une solution de [S4N3][Cl], dans de l’ammoniac liquide, suivie d’une extraction
conduit à la formation d’un mélange réactionnel sec du nouveau composé dinitrido disoufre étain [{n-Bu2Sn(S2N2)}2]
(1). La réaction du composé [{n-Bu2Sn(S2N2)}2] (1) avec les dérivés pentaméthylcyclopentadiényl (Cp*) iridium
[{IrCl(µ-Cl)(η5-C5Me5)}2] ou [(η5-C5Me5)IrCl2(PPh3)] conduit à des produits différents suivant les rapports de réactifs.
Une réaction 1:1 entre 1 et [{IrCl(µ-Cl)(η5-C5Me5)}2] ne conduit qu’au produit [(η5-C5Me5)Ir(S2N2)] (2) avec un
rendement moyen; on obtient le même produit, avec un rendement un peu plus élevé par réaction 2:1 entre 1 et [(η5-
C5Me5)IrCl2(PPh3)]. La réaction du composé 1 avec [(η5-C5Me5)2IrCl2(PPh3)] (rapport molaire 1:1) en présence de
NH4[PF6] conduit à la formation de l’espèce bimétallique inhabituelle [(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-C5Me5)][PF6]
(3). On a déterminé les structures cristallines des composés 1, 2 et 3 par diffraction des rayons X.
Mots clés : ammoniac liquide, réactif azote–soufre étain, métathèse, métallacycle soufre–étain, complexes de l’iridium.
[Traduit par la Rédaction] Aucott et al. 1487
Introduction
treating cis-[MCl2(PR3)2] (M
=
Pt or Pd) with
Silyl and tin reagents have proven useful sources of sulfur–
nitrogen fragments in the synthesis of heterocycles (1, 2). In
many examples the driving force of these reactions is the
formation of M—X (M = Si or Sn; X = Br, Cl, or F) bonds.
Thus, for example, bis(trimethylsilyl)sulfur diimide
(Me3Si)2N2S reacts with S4N4Cl2 and o-C6H4(SCl)2, provid-
ing an [N2S]2– fragment, to give S5N6 (3) and o-C6H4(SN)2S
(4), respectively. Similarly [{Me2Sn(S2N2)}2] (5) supplies an
[S2N2]2– fragment and gives the five-membered ring compounds
C(O)S2N2 (6) and S(O)S2N2 (7) with carbonyl fluoride
(COF2) and thionyl fluoride (SOF2), respectively. Metal sul-
fur nitrides (see references 8 and 9 for reviews) have been pre-
pared analogously from Group 14 sulfur–nitrogen reagents and
metal halides. Examples include formation of the eight-
membered ring compound (MeAsNSN)2 (10) by reaction of
(Me3Si)2N2S with MeAsCl2 and complexes of the type
[M(S2N2H)(PR3)2][X] (X = Me2SnCl3, PF6, or BF4) (11) by
[{Me2Sn(S2N2)}2] via the elimination of Me3SiCl and
Me2SnCl2, respectively. Group 9 metal complexes contain-
ing the [S2N2]2– ligand are uncommon (especially when
compared with those of Group 10 and in particular those of
platinum) examples being [(η5-C5H5)Co(S2N2)] (12–14),
[(η5-C5Me5)Co(S2N2)] (13–14), and [Ir(dppe)2(S2N2)][BPh4]
(15) (dppe = cis-1,2-bis(diphenylphosphino)ethane) prepared
by the action of S4N4 on [(η5-C5H5)Co(CO)2] or [(η5-
C5H5)Co(cod)], [(η5-C5Me5)Co(CO)2], and [Ir(dppe)2(CO)][BPh4],
respectively. We report here the synthesis of two new
organometallic thiazene complexes of iridium [(η5-
C5Me5)Ir(S2N2)] (2) and [(η5-C5Me5)IrCl(PPh3)- (S2N2)Ir(η5-
C5Me5)][PF6] (3) prepared by metathesis using [{n-
Bu2Sn(S2N2)}2] (1), a new example of a dialkyl–SnS2N2
dimer, of which only two other examples are known, the
aforementioned methyl derivative [{Me2Sn(S2N2)}2] (5) and
the tert-butyl analogue [{t-Bu2Sn(S2N2)}2] (16, 17).
Received 2 February 2002. Published on the NRC Research Press Web site at http://canjchem.nrc.ca on 12 November 2002.
Dedicated to Professor Tris Chivers in recognition of his unique contribution to main group chemistry.
S.M. Aucott, A.M.Z. Slawin, and J.D. Woollins.1 School of Chemistry, University of St Andrews, Fife, Scotland KY16 9ST.
1Corresponding author (e-mail: jdw3@st-and.ac.uk).
Can. J. Chem. 80: 1481–1487 (2002)
DOI: 10.1139/V02-085
© 2002 NRC Canada

1482
Can. J. Chem. Vol. 80, 2002
[(η5-C5Me5)Ir(S2N2)] (2)
Experimental
Method A.
To an orange solution of [{IrCl(µ-Cl)(η5-C5Me5)}2]
(197 mg, 0.247 mmol) in dichloromethane (20 cm3) was
added [{n-Bu2Sn(S2N2)}2] (1) (161 mg, 0.248 mmol) in one
portion. Over the course of 25 min the reaction mixture
darkened to a deep red colour and stirring was continued for
a total of 8 h. The reaction mixture was evaporated to dry-
ness under reduced pressure and then taken up in toluene
(25 cm3). The slightly cloudy dark orange solution was then
added to a column of silica (20 × 2 cm) and first eluted with
toluene (200 cm3), which was discarded, and then with ace-
tone; the orange band that moved with the solvent front was
collected and taken to dryness. The residue was dissolved in
the min amount of warm (60–70°C) toluene and stored at
4°C overnight. The resulting well-formed dark orange–red
crystals were collected by suction filtration and dried in
vacuo. Yield: 107 mg, 53%.
General
Unless otherwise stated, manipulations were performed
under an oxygen-free nitrogen or argon atmosphere using
pre-dried solvents and standard Schlenk techniques. The am-
monia used was obtained from BOC Ltd and dried by pas-
sage through a column of NaOH. The reagents [S4N3][Cl]
(18) and [{IrCl(µ-Cl)(η5-C5Me5)}2] (19) were both prepared
according to literature procedures, the latter from
IrCl3·3H2O and pentamethylcyclopentadiene (both Strem).
[(η5-C5Me5)IrCl2(PPh3)] was prepared by treating a CH2Cl2
solution of [{IrCl(µ-Cl)(η5-C5Me5)}2] with 2 equiv of PPh3
(Aldrich) followed by precipitation of the product by the ad-
dition of diethyl ether. [n-Bu2SnCl2], NH4[PF6], and
Ag[PF6] were purchased from Aldrich and used as received.
IR spectra were recorded as KBr pellets in the range
4000–220 cm–1 on a PerkinElmer system 2000 Fourier trans-
1
form spectrometer. H NMR spectra (250 MHz) were ob-
Method B.
[(η5-C5Me5)IrCl2(PPh3)] (245 mg, 0.371 mmol) and [{n-
Bu2Sn(S2N2)}2] (1) (242 mg, 0.372 mmol) were stirred to-
gether in dichloromethane (20 cm3) for 8 h. The product iso-
lation procedure is exactly as described above (Method A).
Yield: 131 mg, 84%. IR (KBr pellet) (cm–1): 2984 (w), 2962
(w), 2921 (w), 2854 (w), 1490 (w), 1458 (s), 1427 (w), 1376
(s), 1158 (w), 1079 (w), 1027 (vs), 957 (s), 701 (vs), 697
(w), 636 (s), 612 (w), 590 (w), 502 (s), 453 (m), 397 (s), 383
tained using a Bruker AC250 FT spectrometer with δ
referenced to external SiMe4, 31P NMR spectra (109.4 MHz
or 101.3 MHz) either on a JEOL GSX270 or a Bruker
AC250 FT spectrometer with δ referenced to external
H3PO4, and 119Sn NMR spectra (100.7 MHz) on a JEOL
GSX270 spectrometer with δ referenced to external SnMe4.
Microanalyses were performed by the University of St An-
drews Chemistry Department Service.
1
(w). H NMR (C6D6) δ: 1.65 (s, 15 H, C5Me5). FAB+-MS
m/z: 420 ([M]+). Anal. calcd. for C10H15IrN2S2 (%): C 28.57,
H 3.60, N 6.67, S 15.22; found: C 28.58, H 3.35, N 6.31,
S 15.17.
Preparations
[{n-Bu2Sn(S2N2)}2] (1)
[(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-C5Me5)][PF6] (3)
Ammonia (~200 cm3) was condensed into a pre-cooled
(–78°C, cardice–acetone) Schlenk flask. [S4N3][Cl] (9.22 g,
44.82 mmol) was added to the ammonia in small portions
over a 5 min period. The resulting dark red reaction mixture
was stirred at –78°C for an additional 30 min. [n-Bu2SnCl2]
(27.24 g, 89.64 mmol) was then added to this mixture in
small portions again over 5 min. Once the addition was com-
plete the reaction vessel was topped with a bubbler and
stirred at –78°C for 2.5 h then the cooling bath was removed
and the reaction gradually warmed to room temperature.
Once the ammonia had evaporated the reaction residue was
dried in vacuo for ca. 1 h before being placed in a Sohxlet
thimble. The residue was extracted with (40–60°C) petro-
leum ether (250 cm3) until the extracts were nearly colour-
less (approximately 4–5 h). The resulting deep orange–red
solution was placed in a freezer (–20°C) overnight and the
deposited bright yellow crystals were collected by filtration
under an atmosphere of nitrogen or argon and washed with
cold (<0°C) hexanes (2 × 100 cm3) and dried in vacuo.
Yield: 20.98 g, 72%. IR (KBr pellet) (cm–1): 2956 (m), 2918
(m), 2871 (m), 2853 (m), 1063 (s), 1033 (vs), 899 (vs), 769
Method A.
To
a
dichloromethane (20 cm3) solution of [(η5-
C5Me5)IrCl2(PPh3)] (237 mg, 0.359 mmol) were added as
solids [{n-Bu2Sn(S2N2)}2] (1) (117 mg, 0.180 mmol) and
NH4[PF6] (45 mg, 0.360 mmol); the resulting red–brown re-
action mixture was stirred for 18 h at room temperature be-
fore filtration through Celite; the Celite was washed with a
further 10 cm3 of dichloromethane. The filtrate and the
washings were evaporated to ca. 15 cm3 and allowed to
slowly decrease in volume over 2 weeks giving a small crop
of orange–brown crystals, which were manually separated
from the reaction residue, washed with diethyl ether, and
dried in vacuo. Yield: 79 mg, 37%. Single crystals suitable
for X-ray analysis were grown by diffusion of diethyl ether
into a dilute dichloromethane solution of 3.
Method B.
To
a
dichloromethane (20 cm3) solution of [(η5-
C5Me5)IrCl2(PPh3)] (105 mg, 0.159 mmol) was added as a
solid Ag[PF6] (40 mg, 0.158 mmol), and the reaction mix-
ture was stirred in the dark for 2 h. To this reaction mixture
was added solid [(η5-C5Me5)Ir(S2N2)] (2) (67 mg, 0.160 mmol)
in one portion and a further 10 cm3 of dichloromethane. The
mixture was stirred for an additional 2 h at room tempera-
ture in the dark and then filtered through Celite to remove
the precipitated AgCl. The filtrate was then evaporated to ca.
5–6 cm3 under reduced pressure. Precipitation was induced
1
(m), 697 (s), 668 (w), 622 (s), 443 (m), 385 (m). H NMR
(C6D6) δ: 1.55–0.78 (m, 36 H, n-Bu). 119Sn (C6D6) δ: 37.8
(br s). EI–CI-MS m/z (%): 267 (n-BuSnS2N2, 20), 210
(SnS2N2, 13), 177 (n-BuSn, 17), 166 (SnSN, 11), 120 (Sn, 9),
64 sulfur–nitrogen(S2, 100), 60 (NSN, 70), and 46 (SN, 35).
Anal. calcd. for C16H36N4S4Sn2 (%): C 29.45, H 5.56, N 8.59,
S 19.62; found: C 29.21, H 5.29, N 8.50, S 19.73.
© 2002 NRC Canada

Aucott et al.
1483
Table 1. Crystallographic data for compounds 1–3.
Crystal
1
2
4
Empirical formula
Crystal colour, habit
Crystal system
Space group
C16H36N4S4Sn2
Yellow, plate
Triclinic
P-1
C10H15IrN2S2
Orange, prism
Monoclinic
P21/n
C38H45ClF6Ir2N2P2S2·2H2O
Yellow, plate
Monoclinic
P21/n
a (Å)
b (Å)
c (Å)
9.2230(7)
14.4851(12)
16.0210(13)
84.692(2)
75.640(2)
88.436(3)
2064.6(3)
3
7.8051(4)
13.3519(6)
12.9863(6)
90
102.2640(10)
90
12.0603(17)
14.879(2)
25.281(4)
90
91.202(3)
90
α (°)
β (°)
γ (°)
V (Å3)
1322.46(11)
4
4553.5(11)
4
Z
Molecular weight
Dcalcd. (mg m–3)
Absorption correction (µ) (mm–1)
F(000)
650.11
1.57
2.13
972
419.56
2.11
10.38
792
1225.70
1.79
6.12
2376
Measured reflections
Observed independent reflections
Final R1, wR2[I > 2σ(I)]
Largest diff. peak hole (e Å–3)
12839
5855
0.0609, 0.1629
0.693, –1.091
5550
1871
0.0238, 0.0535
0.720, –0.855
25195
6470
0.0849, 0.1710
0.2219, 0.2296
by the slow addition of diethyl ether (90 cm3) to the stirred
filtrate to give bright orange micro-crystals, which were col-
lected by suction filtration, washed with diethyl ether
(10 cm3), and dried in vacuo. Yield: 0.151 mg (80%). IR
(KBr pellet) (cm–1): 3080 (w), 3061 (w), 3027 (w), 2990
(w), 2970 (w), 2920 (w), 1484 (w), 1453 (w), 1437 (s), 1386
(w), 1097 (m), 1024 (m), 973 (m), 876 (m), 841 (vs), 781
(w), 756 (m), 746 (s), 738 (m), 701 (s), 558 (s), 530 (s), 513
(m), 494 (m), 453 (w), 440 (w), 414 (w), 398 (w), 257 (w),
were by full-matrix least squares based on F2 using
SHELXTL (20).2
Results and discussion
The addition of [n-Bu2SnCl2] to a reaction mixture of
[S4N3][Cl] in liquid ammonia gives, after extraction of the
dry reaction residue with 40–60°C petroleum ether, the di-
n-butyltin disulfur dinitrido compound [{n-Bu2Sn(S2N2)}2]
(1) in 72% yield (eq. [1]). This reaction represents a more con-
248 (w). 1H NMR (CD2Cl2) δ: 7.67–6.85 (m, 15 H,
4
aromatics), 2.08 (s, 15 H, C5Me5), 1.31 (d, 15 H, J
=
31 P−1 H
3 Hz, C5Me5). 31P NMR (CD2Cl2) δ: 9.7 (PPh3), –143.9
(sept, [PF6]–1, 1J
= 709 Hz). FAB+-MS m/z: 1045
31 P−19 F
([M-(PF6)]+), 625 ([Cp*IrCl(PPh3)]+), 420 ([Cp*Ir(S2N2)]+),
363 ([Cp*IrCl]+). Anal. calcd. for C38H45ClF6Ir2N2P2S2
(%): C 38.31, H 3.81, N 2.35, S 5.37; found: C 37.97, H
3.62, N 2.28, S 4.99.
[1]
The crystals used in the X-ray analysis of 3 were obtained
via Method A. Further characterization was performed using
material synthesized by Method B.
X-Ray crystallography
venient route to this class of compound and uses a commer-
cial source of tin and a stable readily prepared source of sul-
fur and nitrogen. By comparison the two previously reported
examples of this type of compound employ
tris(timethylstannyl)amine [(Me3Sn)3N] and S4N4 (eq. [2])
and the tin starting material 4 and elemental sulfur (eq. [3])
in their syntheses, which give [{Me2Sn(S2N2)}2] and [{t-
Bu2Sn(S2N2)}2] + compound 5, respectively. Compound 1 is
a moderately air- and moisture-sensitive yellow crystalline
Table 1 lists details of data collections and refinements for
1, 2, and 3. Data were collected at room temperature using
Mo Kα radiation with a SMART system. Intensities were
corrected for Lorentz polarization and for absorption. The
structures were solved by the heavy atom method or by di-
rect methods. The positions of the hydrogen atoms were ide-
alized. High thermal motion in the n-butyl groups of
compound 1 meant that the carbon atoms were refined
isotropically subject to distance constraints. Refinements
2 Supplementary data may be purchased from the Depository of Unpublished Data, Document Delivery, CISTI, National Research Council
Canada, Ottawa, ON K1A 0S2, Canada (http://www.nrc.ca/cisti/irm/unpub_e.shtml for information on ordering electronically). CCDC
178367–178369 contain the supplementary data (excluding structure factors) for this paper. These data can be obtained, free of charge, via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, U.K.; fax
+44 1223 336033; or deposit@ccdc.cam.ac.uk).
© 2002 NRC Canada

1484
Can. J. Chem. Vol. 80, 2002
Table 2. Selected bond lengths (Å) and bond angles (°) for [{n-Bu2Sn(S2N2)}2] (1) (listing the three independent n-Bu2Sn(S2N2) units
that make up the unit cell) and [{t-Bu2Sn(S2N2)}2] for comparison.
[{n-Bu2Sn(S2N2)}2] (1)
n-Bu2Sn(S2N2) (1)
Bond lengths (Å)
[{t-Bu2Sn(S2N2)}2]
n-Bu2Sn(S2N2) (2)
n-Bu2Sn(S2N2) (3)
Sn(1)—C(1)
Sn(1)—C(5)
Sn(1)—N(1)
N(1)—S(1)
S(1)—N(2)
N(2)—S(2)
S(2)—Sn(1)
Sn(1)—N(3)
2.1497(7)
Sn(2)—C(9)
Sn(2)—C(13)
Sn(2)—N(3)
N(3)—S(3)
S(3)—N(4)
N(4)—S(4)
S(4)—Sn(2)
Sn(2)—N(1)
2.1499(7)
2.1498(7)
2.144(2)
1.553(6)
1.571(6)
1.681(7)
2.598(2)
2.382(5)
Sn(3)—C(17)
Sn(3)—C(21)
Sn(3)—N(5)
N(5)—S(5)
S(5)—N(6)
N(6)—S(6)
2.1499(8)
2.1501(6)
2.133(5)
1.526(5)
1.552(7)
1.666(7)
2.591(2)
2.349(5)
Sn(1)—C(1)
Sn(1)—C(5)
Sn(1)—N(1)
N(1)—S(1)
S(1)—N(2)
N(2)—S(2)
S(2)—Sn(1)
Sn(1)—N(3)
2.22(1)
2.20(1)
2.15(1)
1.54(1)
1.56(1)
1.66(1)
2.62(7)
2.33(1)
2.1501(7)
2.0995(5)
1.528(6)
1.571(6)
1.621(6)
2.594(2)
2.322(5)
S(6)—Sn(3)
Sn(3)—N(5A)
Bond angles (°)
N(1)-Sn(1)-C(1)
N(1)-Sn(1)-C(5)
C(1)-Sn(1)-C(5)
N(1)-Sn(1)-N(3)
N(1)-Sn(1)-S(2)
C(1)-Sn(1)-S(2)
C(5)-Sn(1)-S(2)
S(1)-N(1)-Sn(1)
Sn(1)-N(1)-Sn(2)
N(1)-S(1)-N(2)
S(1)-N(2)-S(2)
N(2)-S(2)-Sn(1)
115.4(2)
121.3(2)
120.77(3)
72.9(2)
79.81(15)
100.92(7)
104.21(7)
123.1(3)
107.7(2)
113.9(3)
121.4(4)
101.8(2)
N(3)-Sn(2)-C(9)
N(3)-Sn(2)-C(13)
C(9)-Sn(2)-C(13)
N(3)-Sn(2)-N(1)
N(3)-Sn(2)-S(4)
C(9)-Sn(2)-S(4)
C(13)-Sn(2)-S(4)
S(3)-N(3)-Sn(2)
Sn(2)-N(3)-Sn(1)
N(3)-S(3)-N(4)
S(3)-N(4)-S(4)
116.4(2)
113.7(2)
128.06(3)
70.9(2)
N(5)-Sn(3)-C(17)
N(5)-Sn(3)-C(21)
C(17)-Sn(3)-C(21)
N(5)-Sn(3)-N(5A)
N(5)-Sn(3)-S(6)
C(17)-Sn(3)-S(6)
C(21)-Sn(3)-S(6)
S(5)-N(5)-Sn(3)
Sn(3)-N(5)-Sn(3A)
N(5)-S(5)-N(6)
116.3(2)
112.8(2)
128.55(6)
72.5(2)
79.9(1)
99.4(1)
103.4(1)
122.0(3)
107.5(2)
116.0(3)
120.0(4)
102.1(2)
N(1)-Sn(1)-C(1)
N(1)-Sn(1)-C(5)
C(1)-Sn(1)-C(5)
N(1)-Sn(1)-N(3)
N(1)-Sn(1)-S(2)
C(1)-Sn(1)-S(2)
C(5)-Sn(1)-S(2)
S(1)-N(1)-Sn(1)
Sn(1)-N(1)-Sn(2)
N(1)-S(1)-N(2)
S(1)-N(2)-S(2)
N(2)-S(2)-Sn(1)
118.7(5)
117.7(5)
123.4(5)
72.7(5)
80.2(3)
96.1(4)
80.9(2)
100.95(7)
99.32(7)
120.5(3)
108.3(2)
116.7(3)
119.5(4)
102.0(2)
96.2(4)
120.8(6)
107.2(4)
116.9(7)
120.2(9)
101.8(5)
S(5)-N(6)-S(6)
N(6)-S(6)-Sn(3)
N(4)-S(4)-Sn(2)
[2]
Fig. 1. Crystal structure of [{n-Bu2Sn(S2N2)}2] (1) showing the
1.5 independent molecules.
[3]
solid that is extremely soluble in most common organic
solvents including pentane and hexane. The 1H NMR (C6D6)
is uninformative and is very similar to that of its precursor
[n-Bu2SnCl2] with no evident 1H-117Sn or 1H-119Sn cou-
plings. The 119Sn NMR (C6D6) consists of a broad singlet at
37.8 ppm while the corresponding value of n-Bu2SnCl2 is
124.7 ppm. The IR spectrum shows absorptions that are
comparable to those reported for [{Me2Sn(S2N2)}2] (5). The
EI–CI mass spectrum of 1 failed to show the molecular ion
of either the dimer or monomer, however it did show m/z
267, which corresponds to [n-BuSnS2N2]+ along with other
tin-containing fragments (see Experimental); in addition ele-
mental analysis was within specified limits. The slow pas-
sage of nitrogen for 24 h over a diethyl ether solution of 1
led to small but well-formed crystals that were suitable for
X-ray analysis. The crystal structure of 1 (Fig. 1) and se-
lected bond lengths and angles together with those of
[{t-Bu2Sn(S2N2)}2] for comparison are given (Table 2). The
X-ray structural determination of [{n-Bu2Sn(S2N2)}2] (1)
identified the SnS2N2 unit as a 1,3,2,4,5-dithiadiazastannole
© 2002 NRC Canada

Aucott et al.
1485
Scheme 1. (i) [{IrCl(µ-Cl)(η5-C5Me5)}2]; (ii) [(η5-C5Me5)IrCl2(PPh3)]; (iii) [(η5-C5Me5)IrCl2(PPh3)], NH4[PF6]; (iv) [(η5-
C5Me5)IrCl2(PPh3)], Ag[PF6], [(η5-C5Me5)Ir(S2N2)].
Fig. 2. Crystal structure of [(η5-C5Me5)Ir(S2N2)] (2).
ring and highlighted the dimeric nature of the molecule. The
unit cell of [{n-Bu2Sn(S2N2)}2] (1) contains 1.5 independent
molecules consisting of three distinct n-Bu2Sn(S2N2) mono-
mer units that have similar bond lengths and angles. The ge-
ometry about the tin atoms is distorted trigonal bipyramidal,
the n-butyl groups and the tin-bound nitrogen atoms of the
SnS2N2 rings in the equatorial positions with the tin-bound
sulfur atoms of each SnS2N2 unit and the bridging nitrogen
atoms occupying the axial sites. The three bond angles in the
trigonal plane are all close to 120°, but the axial substituents
occupy far from linear positions with average S-Sn-N =
152.3°. The ring Sn—N and Sn—S distances are close to
those found in [{t-Bu2Sn(S2N2)}2] (17) and [{Me2Sn(S2N2)}2]
(21) as is the pattern of average S—N bond lengths within
the SnS2N2 ring, i.e., short (1.536 Å), medium (1.566 Å),
and long (1.656 Å), a pattern also observed in other MS2N2
rings, for example [(H3N)Pb(S2N2)] (22). The four-
membered Sn2N2 rings are parallelograms, formed by the n-
Bu2Sn(S2N2) dimer pairs and have average internal angles of
N-Sn-N = 72.08° and Sn-N-Sn = 107.83°. The [Sn(S2N2)]2
unit of the dimer consisting of two different n-Bu2Sn(S2N2)
molecules is essentially planar with a mean deviation from
the least squares plane of 0.06 Å and a maximum deviation
of only 0.10 Å above the plane for Sn(1). The second pic-
tured dimer made up of two repeat n-Bu2Sn(S2N2) units is
closer to planarity with a mean deviation of 0.01 Å and a
maximum deviation above the plane of 0.03 Å for N(5).
ably the by-products of the reaction between 1 and PPh3,
which we were unable to identify (Scheme 1). The air- and
moisture-tolerant orange–red crystalline product is highly
soluble in chlorinated solvents, benzene, and toluene and is
slightly soluble in diethyl ether but is much less so in petro-
leum ether, hexane, and alcohols. The H NMR (CD2Cl2)
data shows the 15 Cp* (Cp* = pentamethylcyclopentadienyl)
1
A previous attempt to obtain monocyclopentadienyl IrS2N2
complexes via oxidative addition to [(η5-C5H5)Ir(CO)2] with
S4N4, a method that works well for the cobalt analogues
[(η5-C5H5)Co(CO)2] and [(η5-C5Me5)Co(CO)2], gave only
an insoluble black precipitate (14). An alternative synthetic
method involving the treatment of [{IrCl(µ-Cl)(η5-C5Me5)}2]
with [{n-Bu2Sn(S2N2)}2] (1) in dichloromethane proceeds
via the elimination of [n-Bu2SnCl2] (119Sn NMR evidence)
and gives after chromatography on silica (eluting first with
toluene and then with acetone) [(η5-C5Me5)Ir(S2N2)] (2) in
53% yield (Scheme 1). Alternatively compound 2 can be
prepared in higher yield (84%) by the reaction of 1 equiv of
1 and [(η5-C5Me5)IrCl2(PPh3)], which proceeds via the elim-
ination of PPh3 (which undergoes further reaction with
0.5 equiv of 1 to give P(S)Ph3 (31P NMR evidence) and
[n-Bu2SnCl2] (119Sn NMR evidence); also shown by
119Sn NMR were a number of other 119Sn signals, presum-
methyl group protons as a sharp singlet at δ 1.65 compared
4
with 1.51 and a doublet at 1.32 J
= 2 Hz (both CD2Cl2)
31 P−1 H
for [{IrCl(µ-Cl)(η5-C5Me5)}2] and [(η5-C5Me5)IrCl2(PPh3)],
respectively. The vibrational spectrum of complex 2 (KBr
pellet) shows the expected bands due to the [S2N2]2– ligand
at 1027 (vs) ν(NS), 701 (vs) ν(NS), 636 (s) ν(NS), 453 (m)
ν(IrN), 397 (m) δ(NS), and 383 (w) cm–1 ν(IrS). Micro-
analytical data were in excellent agreement with the pro-
posed formulation and the positive-ion FAB+ mass spectra
showed the molecular ion of 2 at m/z 420 ([M]+). Large
well-formed orange–red crystals, which were of X-ray qual-
ity were obtained by crystallization from hot (60–70°C) to-
luene. The X-ray structure of [(η5-C5Me5)Ir(S2N2)] (2) is
shown in Fig. 2 with bond distances and angles in Table 3
(along with those of [Ir(dppe)2(S2N2)][BPh4] (15) for com-
parison) and reveals that the IrS2N2 cycle is essentially pla-
nar, the largest deviation from the mean plane being only
© 2002 NRC Canada

1486
Can. J. Chem. Vol. 80, 2002
Table 3. Selected bond lengths (Å) and bond angles (°) for [(η5-C5Me5)Ir(S2N2)] (2), [(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-
C5Me5)][PF6]·2H2O (3), and [Ir(dppe)2(S2N2)][BPh4].
[(η5-C5Me5)Ir(S2N2)] (1)
Bond lengths (Å)
(3)
[Ir(dppe)2(S2N2)][BPh4]
Ir(1)—N(1)
N(1)—S(1)
S(1)—N(2)
N(2)—S(2)
S(2)—Ir(2)
Ir(1)—C(1)
Ir(1)—C(2)
Ir(1)—C(3)
Ir(1)—C(4)
Ir(1)—C(5)
1.962(6)
1.509(7)
1.563(9)
1.632(8)
2.175(2)
2.172(6)
2.192(6)
2.178(6)
2.194(6)
2.191(6)
Ir(1)—N(1)
N(1)—S(1)
S(1)—N(2)
N(2)—S(2)
S(2)—Ir(2)
Ir(1)—C(31)
Ir(1)—C(32)
Ir(1)—C(33)
Ir(1)—C(34)
Ir(1)—C(35)
Ir(2)—Cl(1)
Ir(2)—P(1)
Ir(2)—N(2)
1.961(10)
1.558(10)
1.531(9)
1.685(9)
2.179(3)
2.120(12)
2.183(10)
2.120(11)
2.179(12)
2.158(10)
2.421(3)
2.336(3)
2.178(8)
Ir(1)—N(1)
N(1)—S(1)
S(1)—N(2)
N(2)—S(2)
S(2)—Ir(2)
2.289(12)
1.38(2)
1.75(2)
1.40(2)
2.379(9)
Bond angles (°)
120.2(4)
112.4(3)
114.0(4)
108.3(3)
85.1(2)
Ir(1)-N(1)-S(1)
N(1)-S(1)-N(2)
S(1)-N(2)-S(2)
N(2)-S(2)-Ir(1)
S(2)-Ir(1)-N(1)
P(1)-Ir(2)-Cl(1)
P(1)-Ir(2)-N(2)
N(2)-Ir(2)-Cl(1)
Ir(2)-N(2)-S(1)
Ir(2)-N(2)-S(2)
120.6(5)
110.0(5)
117.4(5)
105.5(3)
86.5(3)
90.39(10)
90.6(2)
86.4(2)
Ir(1)-N(1)-S(1)
N(1)-S(1)-N(2)
S(1)-N(2)-S(2)
N(2)-S(2)-Ir(1)
S(2)-Ir(1)-N(1)
111.1(8)
119.7(9)
117.4(10)
109.0(8)
82.5(4)
Ir(1)-N(1)-S(1)
N(1)-S(1)-N(2)
S(1)-N(2)-S(2)
N(2)-S(2)-Ir(1)
S(2)-Ir(1)-N(1)
125.1(5)
117.1(5)
0.007 Å with an S2N2 “bite angle” of 85.1(2)°. The bond
lengths within the S2N2 unit of 1, i.e., short (1.509(7) Å),
medium (1.563(9) Å), and long (1.632(8) Å) seem to be in
good agreement with those noted in previous studies (23–24)
on monomeric PtS2N2 species, and in particular are consistent
with the values reported for the only other crystallographi-
cally characterized monocyclopentadienyl MS2N2 complex
[(η5-C5H5)Co(S2N2)] (12), i.e., short (1.548(3) Å), medium
(1.579(4) Å), and long (1.650(4) Å).
The 31P NMR (CD2Cl2) data of 3 shows two phosphorus en-
vironments, a singlet at δ 9.7 ppm (cf. δ 2.4 (CD2Cl2) for
[(η5-C5Me5)IrCl2(PPh3)]) assigned to the PPh3 ligand and
the anticipated septet centred at –143.9 ppm due to the
[PF6]– counter-ion. The IR spectra of 3 (KBr pellet) displays
characteristic absorption at 1024 (m) ν(NS), 701 (s) ν(NS),
636 (s) ν(NS), and 398 (w) cm–1 δ(NS) of the [S2N2]2–
ligand (8, 23, 24, 25) and also a very strong band at
841 cm–1, which is characteristic of the [PF6]– anion. Micro-
analytical data were in good agreement with the proposed
structure and the positive-ion FAB+ mass spectra showed
[M-(PF6)]+ at m/z 1045 along with several other identifiable
fragments. Crystals suitable for X-ray crystallography were
grown over 4 days by layering a dichloromethane solution
of 3 with diethyl ether. Figure 3 shows a perspective view of
the complex cation of 3 (water molecules and the [PF6]–
counter ion are not shown for the sake of clarity) and se-
lected bond distances and angles are given in Table 3. The
coordination geometry around Ir(1) closely resembles that in
the mononuclear complex 2 (mean deviation from IrS2N2
plane = 0.008 Å) and it is evident that coordination to Ir(2)
by the non-metal bound nitrogen N(2) causes only minimal
changes in the bond lengths and bond angles of the IrS2N2
cycle. The geometry about Ir(2) is unremarkable; the
P(1)-Ir(2)-Cl(1), P(1)-Ir(2)-N(2), and N(2)-Ir(2)-Cl(1) bond
angles all being close to 90°. The iridium atom of the
(η5-C5Me5)IrCl(PPh3) group Ir(2) lies 0.28 Å below the
Ir(1)S2N2 plane and the Ir(2)-N(2) bond length 2.178(8) Å
and the Ir(2)-N(2)-S(1) and Ir(2)-N(2)-S(2) bond angles
The reaction of [(η5-C5Me5)IrCl2(PPh3)] with 0.5 equiv of
1 in the presence of NH4[PF6] leads to the unusual bimetallic
complex [(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-C5Me5)][PF6]·2H2O
(3) in low yield (37%) and poor purity (Scheme 1). A more
rational approach, which gives this material in much higher
yield (80%) and of more satisfactory purity involves the ab-
straction of a chloride ligand from [(η5-C5Me5)IrCl2(PPh3)]
with Ag[PF6] followed by treatment of the resulting
coordinatively unsaturated species with pre-formed [(η5-
C5Me5)Ir(S2N2)] (2). The resulting bright orange micro-
crystalline product is soluble in alcohols, THF, and chlori-
nated solvents, sparingly soluble in benzene and toluene, and
1
insoluble in diethyl ether and hexane. The H and 31P NMR
data (C6D6) of the dry crude reaction mixture suggests that
this reaction proceeds cleanly to give only [(η5-
C5Me5)IrCl(PPh3)(S2N2)Ir(η5-C5Me5)][PF6] (3), as only two
Cp* environments are evident (Scheme 1). The first, bound
to the iridium centre bearing the PPh3 ligand, is a doublet at
δ 1.31 4J
= 2 Hz; the singlet at δ 2.08 we have as-
31 P−1 H
signed to the Cp* ligand of the (S2N2)Ir(η5-C5Me5)] moiety.
© 2002 NRC Canada

Aucott et al.
1487
Fig. 3. Crystal structure of [(η5-C5Me5)IrCl(PPh3)(S2N2)Ir(η5-
C5Me5)][PF6]·2H2O (3) (the water molecules and the [PF6]–
counter ion have been omitted for clarity).
References
1. A.Y. Makarov, I.Y. Bagryanakaya, Y.V. Gatilov, T.V.
Mikhalina, M.M. Shakirov, L.N. Shchegoleva, and A.V.
Zibarev. Heteroatom Chem. 12(7), 563 (2001).
2. A.Y. Makarov, M.A. Shakirov, K.V. Shuvaev, I.Y.
Bagryanakaya, Y.V. Gatilov, and A.V. Zibarev. Chem.
Commun. 1774, (2001).
3. W.S. Sheldrick, M.N.R. Sudheendra, and H.W. Roesky. Inorg.
Chem. 19, 538 (1980).
4. J.L. Morris, C.W. Rees, and D.J. Rigg. J. Chem. Soc. Chem.
Commun. 7, 396 (1985).
5. H.W. Roesky and H. Weizer. Angew. Chem. Int. Ed. Engl. 12,
674 (1973).
6. H.W. Roesky and M. Witt. Inorg. Synth. 25, 49 (1989).
7. H.W. Roesky. Z. Naturforsch. 31B, 680 (1976).
8. P.F. Kelly and J.D. Woollins. Polyhedron, 5, 607 (1985).
9. P.F. Kelly, A.M.Z. Slawin, D.J. Williams, and J.D. Woollins.
Chem. Soc. Rev. 245 sulfur–nitrogen(1992).
10. O.J. Scherer and R. Wies. Angew. Chem. Int. Ed. Engl. 11,
529 (1972).
11. R. Jones, C.P. Warrens, D.J. Williams, and J.D. Woollins. J.
Chem. Soc. Dalton Trans. 907 (1987).
12. F. Edelmann. J. Organomet. Chem. 228, C47 (1982).
13. G. Granozzi, M. Casarin, F. Edelmann, T.A. Albright, and
E.D. Jemmis. Organometallics, 6, 2223 (1987).
14. R.T. Boeré, B.Klassen, and K.H. Moock. J. Organomet. Chem.
467, 127 (1994).
117.1(5) and 125.1(5)° are in excellent agreement with
those of the only other known example of a similar binu-
clear dithiadiaza complex — [Ir(dppe)2(S2N2){W(CO)5}][BPh4]
(15) [W—N(2) = 2.22(2) Å, W-N(2)-S(1) and W-N(2)-S(2) =
117.6(10) and 126.6(11)°, respectively.
15. C.A. Ghilardi, S. Midollini, S. Moneti, and A. Orlandini. J.
Organomet. Chem. 312, 383 (1986).
16. D. Hänssgen, H. Salz, S. Rheindorf, and C. Schrage. J.
Organomet. Chem. 443, 61 (1993).
17. D. Hänssgen, M. Jansen, W. Assenmacher, and H. Salz. J.
Conclusion
The synthesis of [{n-Bu2Sn(S2N2)}2] (1) from [n-
Bu2SnCl2] and [S4N3][Cl] in liquid ammonia represents a
convenient high-yield preparation of a potentially syntheti-
cally useful reagent. This usefulness is highlighted by its use
in the preparation of [(η5-C5Me5)Ir(S2N2)] (2) only the third
known monocyclopentadienyl MS2N2 complex and the first
iridium example of this type of compound in good yield.
This synthetic procedure involving the metathesis of metal
halides with [{n-Bu2Sn(S2N2)}2] (1) is currently being ap-
plied to the preparation of other monocyclopentadienyl
MS2N2 complexes. We have also shown that novel binuclear
species can be readily prepared from [(η5-C5Me5)Ir(S2N2)]
(2) by simple halide abstraction reactions, which we are also
studying in more detail.
Organomet. Chem. 445, 61 (1993).
18. W.L. Jolly and K.D. Maguire. Inorg. Synth. 9, 103 (1967).
19. C. White, A.Yates, and P.M. Maitliss. Inorg. Synth. 29, 228
(1992).
20. G.M. Sheldrick. 1999. SHELXTL [computer program]. Bruker
AXS, Madison, WI.
21. H.W. Roesky. Adv. Inorg. Chem. Radiochem. 22, 245 (1979).
22. H. Martan and J.Weiss. Z. Anorg. Allg. Chem. 514, 107 (1984).
23. P.A. Bates, M.B.Hursthouse, P.F. Kelly, and J.D. Woollins. J.
Chem. Soc. Dalton Trans. 2367 (1986).
24. P.F. Kelly, A.M.Z. Slawin, D.J. Williams, and J.D. Woollins.
Polyhedron, 7, 1925 (1988).
25. D.B. Powell and J.D. Woollins. Spectrochim. Acta, A36, 447
(1980).
© 2002 NRC Canada