Thioacylsulfanylarsines (RCS2)xAsPh3-x, x = 1-3: Synthesis, structures, natural bond order analyses and reactions with piperidine

Article abstract of DOI:10.1039/b008702p

A series of thioacylsulfanylarsines ((RCS₂)AsPh₂, (RCS₂)₂AsPh, (RCS₂)₃As) were synthesized by treating piperidinium dithiocarboxylates with Ph₂AsCl, PhAsCl₂ or AsCl₃, respectively and characterized. Their molecular structures were determined by X-ray crystallography and compared with those of the corresponding acylsulfanyl derivatives ((RCOS)AsPh₂, (RCOS)₂AsPh, (RCOS)₃As). They exist as monomers, and the environment around the arsenic atoms is distorted tetrahedral with one lone pair at the apex. The structure of the mono(dithiocarboxylate) is different from that of the corresponding thiocarboxylic acid derivative, while the bis and tris derivatives showed similar structure to the corresponding thiocarboxylic acid derivatives ((RCOS)₂AsPh, (RCOS)₃As), respectively. The new compounds showed intramolecular interactions between the thiocarbonyl sulfur and the central arsenic atom. NBO (Natural Bond Orbital) analyses performed on the model compounds (CH₃CS₂)As(CH₃)₂ and (CH₃CS₂¹)-(CH₃CS₂² )AsCH₃ at the RHF/LANL2DZ level of theory showed the presence of interactions between the non-bonding orbitals on the thiocarbonyl sulfur (n_s) and the σ*_MS orbitals together with that between the n_s and the σ*_MC orbitals for the former compound; for the latter the presence of both orbital interactions between n_s and σ*_MS1 and between n_s and σ*_MS2 are present. The reaction of the mono(dithiocarboxylate) derivative (R = 4-CH₃-C₆H₄) with piperidine in ethanol gave piperidinium diphenyldithioarsinate along with the corresponding N-thioacyl- or N-acyl-piperidine. A similar reaction of the bis(dithiocarboxylate) derivative (R = 4-CH₃C₆H₄) gave the novel di(piperidinium) phenyltrithioarsonate in which two anion charges are delocalized on the AsS₃ moiety and a cyclic phenylarsine sulfide tetramer (PhAsS)₄. The diphenyldithioarsinate and phenyltrithioarsonate salts exist as a dimer and a polymer, respectively, in which 12-membered rings are formed by intermolecular N-H ... S hydrogen bonds.

Full text of DOI:10.1039/b008702p

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Thioacylsulfanylarsines (RCS2)xAsPh3 Ϫ x, x ؍ 1–3: synthesis,
structures, natural bond order analyses and reactions with
piperidine†
Kazuyasu Tani, Shin-ichi Hanabusa, Shinzi Kato,* Shin-ya Mutoh, Shun-ichi Suzuki and Masaru Ishida
Department of Chemistry, Faculty of Engineering, Gifu University,
1-1 Yanagido Gifu 501-1193, Japan. E-mail: shinzi@apchem.gifu-u.ac.jp
Received 30th October 2000, Accepted 15th January 2001
First published as an Advance Article on the web 13th February 2001
A series of thioacylsulfanylarsines ((RCS2)AsPh2, (RCS2)2AsPh, (RCS2)3As) were synthesized by treating
piperidinium dithiocarboxylates with Ph2AsCl, PhAsCl2 or AsCl3, respectively and characterized. Their molecular
structures were determined by X-ray crystallography and compared with those of the corresponding acylsulfanyl
derivatives ((RCOS)AsPh2, (RCOS)2AsPh, (RCOS)3As). They exist as monomers, and the environment around the
arsenic atoms is distorted tetrahedral with one lone pair at the apex. The structure of the mono(dithiocarboxylate)
is different from that of the corresponding thiocarboxylic acid derivative, while the bis and tris derivatives showed
similar structure to the corresponding thiocarboxylic acid derivatives ((RCOS)2AsPh, (RCOS)3As), respectively.
The new compounds showed intramolecular interactions between the thiocarbonyl sulfur and the central arsenic
atom. NBO (Natural Bond Orbital) analyses performed on the model compounds (CH3CS2)As(CH3)2 and (CH3CS1 )-
2
(CH3CS2 )AsCH3 at the RHF/LANL2DZ level of theory showed the presence of interactions between the non-
2
bonding orbitals on the thiocarbonyl sulfur (nS) and the σ*MS orbitals together with that between the nS and the
σ*MC orbitals for the former compound; for the latter the presence of both orbital interactions between nS and
σ*MS1 and between ns and σ*MS2 are present. The reaction of the mono(dithiocarboxylate) derivative (R = 4-CH3-
C6H4) with piperidine in ethanol gave piperidinium diphenyldithioarsinate along with the corresponding N-thioacyl-
or N-acyl-piperidine. A similar reaction of the bis(dithiocarboxylate) derivative (R = 4-CH3C6H4) gave the novel
di(piperidinium) phenyltrithioarsonate in which two anion charges are delocalized on the AsS3 moiety and a cyclic
phenylarsine sulfide tetramer (PhAsS)4. The diphenyldithioarsinate and phenyltrithioarsonate salts exist as a dimer
and a polymer, respectively, in which 12-membered rings are formed by intermolecular N–H ؒ ؒ ؒ S hydrogen bonds.
arsenic() ammonium salts.8 Recently the structure of tris-
Introduction
(benzoylsulfanyl)arsine was reported by Nöth and co-workers.9
The chemistry of arsenic compounds with dithio-carbamato
This prompted us to reveal our results concerning Group 15
and -carbonato ligands has been investigated in great detail.1 In
element derivatives of thio- and dithio-carboxylic acids. We
contrast, the preparation of arsenic compounds with thio- and
describe here in detail the synthesis and structural analyses of a
dithio-carboxylato ligands was limited to only seven thiocarb-
series of dithiocarboxyarsines [(RCS2)xAsPh3 Ϫ x, x = 1–3] along
with a structural comparison with the corresponding thio-
carboxyarsines [(RCOS)xAsPh3 Ϫ x, x = 1–3] and in addition
oxylic2 and two dithiocarboxylic acid arsenic derivatives3 when
our study began in 1974. Their spectral data and crystal struc-
ture analyses have not been described. The reason for this
seemed to be the difficulty of purification and of the prepar-
reactions with amines, leading to the first isolation of the
2Ϫ
organotrithioarsonate dianion RAsS3
.
ation of the starting compounds such as dithiocarboxylic
acids and their alkali metal and ammonium salts. The arsenic
compounds with dithio- and thio-carboxylato ligands are
considered to be effective precursors for the synthesis of
organoarsenic thiolate anion species such as R2AsSϪ,4 which
can be used easily to introduce the arsenic–sulfur framework
into a molecule. It is possible that the reactions of alkali
metal diorganoarsenides with elemental sulfur may be used for
the synthesis of organoarsenic thiolates. In our research the
preparation of R2AsϪMϩ (M = alkali metal) appeared to be
impractical. We previously developed convenient syntheses of
ammonium and alkali metal chalcogenocarboxylates,5 and syn-
thesized a variety of their main group element derivatives.6 In
addition, diphenyl(selenocarboxylato)arsines7 have been found
to be effective precursors for the synthesis of diphenylseleno-
Results and discussion
Synthesis of complexes
Initially, the synthesis of diphenyl(dithiocarboxy)arsines 3,
phenylbis(dithiocarboxy)arsines and tris(dithiocarboxy)-
4
arsines 5 was examined using piperidinium 4-methylbenzene-
carbodithioate. Under the conditions as shown in Scheme 1
these compounds were obtained in 70–90% yields.10a Although
small amounts of alkanedithioic acid derivatives are lost during
purification, the main reactions (to give 3, 4 and 5) proceed
quantitatively. In order to compare structure and spectral
data, a series of diphenyl(thiocarboxy)arsines 6, phenyl-
bis(thiocarboxy)arsines 7 and tris(thiocarboxy)arsines 8 were
synthesized in similar yields by treating potassium thio-
carboxylates 2 instead of piperidinium dithiocarboxylates 110b
(Scheme 1). The resulting dithio- and thio-carboxylic acid
arsenic derivatives (especially aromatic derivatives) are stable
both thermally and toward oxygen and water. Upon exposure
† Electronic supplementary information (ESI) available: characteris-
ation data for compounds 3–8, selected bond lengths and angles for 3g,
4e, 5e, 6h, 7g, 8e, 9 and 15. See http://www.rsc.org/suppdata/dt/b0/
b008702p/
518
J. Chem. Soc., Dalton Trans., 2001, 518–527
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b008702p

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Scheme 1
to air they do not show any appreciable change for three
months.
Crystal structures
The structures of (4-methoxythiobenzoylsulfanyl)diphenyl-
3g, bis(4-methylthiobenzoylsulfanyl)phenyl- 4e and tris(4-
methylthiobenzoylsulfanyl)arsine 5e are shown in Fig. 1. The
dithiocarboxylato ligand and the phenyl ring containing C(21)
in 3g are twisted (S(11)–As(1)–C(21)–C(22) 60.0(2)Њ) (Fig. 1a).
In 4e the two dithiocarboxyl ligands exist in the same plane
with the same orientation, where two thiocarbonyl sulfurs are
located in the same direction (Fig. 1b). In 5e the three dithio-
carboxylato ligands exist in C3 symmetry and no two ligands
of the three exist in the same plane (Fig. 1c). The distances
between the central As atom and the thiocarbonyl sulfur
(As(1) ؒ ؒ ؒ S 2.96–3.15 Å) are within the sum of the van der
Waals radii of both atoms (3.65 Å),11 indicating interactions
between the unshared electron pair on the thiocarbonyl sulfur
and the σ* orbitals of the As–S and/or As–Cipso bonds (S(11)–
As(1)–C(31) 155.54(8)Њ). It is noted that the two As ؒ ؒ ؒ S dis-
tances in 4e (As(1) ؒ ؒ ؒ S(11) 2.958(4), As(1) ؒ ؒ ؒ S(21) 2.956(4)
Å) are shorter than those in the mono 3g (3.1470(8) Å) and tris
derivatives 5e (2.969(4) Å). This may facilitate interaction
because the two dithiocarboxylato ligands of 4e exist in the
same plane. These complexes can be described as having a dis-
torted tetrahedral structure and the bonds around the As atoms
can be considered to exhibit a p3-type bond.1b,g
Fig. 1 Molecular structures of (a) (4-CH3OC6H4CS2)AsPh2 3g, (b) (4-
CH3C6H4CS2)2AsPh 4e and (c) (4-CH3C6H4CS2)3As 5e. The thermal
ellipsoids represent 50% probability. Hydrogen atoms are omitted for
clarity.
For comparison, the structure analyses of the corresponding
thiocarboxylato complexes were carried out. The ORTEP12
drawings of (4-chlorobenzoylsulfanyl)diphenyl- 6h, bis(4-
methoxybenzoylsulfanyl)phenyl- 7g and tris(4-methylbenzoyl-
sulfanyl)arsine 8e are shown in Fig. 2. Unlike the dithiocarb-
oxylato complex 3g, the thiocarboxylato ligand of 6h exists
nearly in the same plane as the phenyl ring containing C(21).
Although the crystal system and space group of 7g are different
from those of 4e, the structures of both compounds resemble
one another (Fig. 2b). The structure of 8e is comparable to
both that in 5e and the recently reported tris(benzoylsulfanyl)-
arsine9 (Fig. 2c). Similarly to dithiocarboxylato complexes, the
distances between the central As atom and the carbonyl
oxygens (As ؒ ؒ ؒ O 2.71–2.94 Å) are elongated in the order bis
7g, tris 8e, mono 6h.
where the two CSSAs planes (C(11*)–S(11*)–S(12*)–As(1) and
C(11)–S(11)–S(12)–As(1*)) are parallel, the distance between
the planes being 1.37 Å and the distance between As(1*) and
S(11) (or As(1) ؒ ؒ ؒ S(11*)) is significantly short (3.939 Å),
although greater than the sum of the van der Waals radii of
both atoms. In contrast such a pairing of the molecules is not
observed for the other compounds as shown in Fig. 3 (b) and
also for the corresponding phosphorus isologues ((RCES)PPh2,
E = O or S).12
Structural comparison with the phosphorus isologues
In Table 1 the distances between the thiocarbonyl sulfur or
carbonyl oxygen and the central arsenic atom are collected
along with the C᎐E ؒ ؒ ؒ P (E = O or S) distances of the corre-
᎐
sponding phosphorus isologues. Interestingly, despite the large
atomic radius of arsenic compared with that of phosphorus,
Packing
The molecular arrangement of compounds 3g and 6h is shown
in Fig. 3. It is noteworthy that in 3g two molecules form a pair
the C᎐S ؒ ؒ ؒ As distances are close to those in the corresponding
᎐
phosphorus isologues. In addition, the C᎐O ؒ ؒ ؒ As distance
᎐
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519

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Table 1 Distances between the thiocarbonyl sulfur or carbonyl oxygen and As or P in (RCES)xAsPh3 Ϫ x and (RCES)xPPh3 Ϫ x
Fig. 3 Molecular arrangement of (a) (4-CH3OC6H4CS2)AsPh2 3g and
(b) (4-ClC6H4COS)AsPh2 6h.
As distance (2.943(3) Å) is ca. 0.02 Å longer than that in the
similar phosphorus compound ((4-CH3C6H4COS)PPh2).
Ab initio calculations
To elucidate the nature of these non-bonding attraction, ab
initio geometry optimizations at the RHF/LANL2DZ level
with the GAUSSIAN 94 program15 were performed on the
model compounds (acetylsulfanyl)dimethyl-phosphine 1Ј and
-arsine 2Ј and dimethyl(thioacetylsulfanyl)-phosphine 1Љ and
-arsine 2Љ for (RCES)M(CH3)2 (E = O or S; M = P or As)
and bis(acetylsulfanyl)methyl-phosphine 3Ј and -arsine 4Ј and
bis(thioacetylsulfanyl)methyl-phosphine 3Љ and -arsine 4Љ for
(RCES)2MCH3 (E = O or S; M = P or As). The NBO (natural
bond orbital) analyses showed that orbital interactions between
Fig. 2 Molecular structures of (a) (4-ClC6H4COS)AsPh2 6h, (b) (4-
CH3OC6H4COS)2AsPh 7g and (c) (4-CH3C6H4COS)3As 8e. Details as
in Fig. 1.
(av. 2.720(3) Å) in the bis(thiocarboxylate) 7g is about 0.04 Å
shorter than the C᎐O ؒ ؒ ؒ P distance (av. 2.765(3) Å) in the
᎐
corresponding phosphorus compounds. In the mono(thio-
carboxylate) derivative 6h ((4-ClC H COS)AsPh ) the C᎐O ؒ ؒ ؒ
᎐
6
4
2
520
J. Chem. Soc., Dalton Trans., 2001, 518–527

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Table 2 NBO analysis of (CH3CES)M(CH3)2 and (CH3CES)2MCH3
(E = O or S; M = P or As) at RHF/LANL2DZ levels of theory
(CH3CES)M(CH3)2
∆Ea/kcal molϪ1
nE→σ*MC6
No.
E
M
nE→σ*MS
1Ј
2Ј
1Љ
2Љ
O
O
S
P
As
P
0.55
0.77
1.46
2.22
—
—
0.62
0.84
S
As
(CH3CES)2MCH3
∆Ea/kcal molϪ1
nE→σ*MC10
No.
E
M
nE→σ*MS2
nE→σ*MS3
3Ј
4Ј
3Љ
4Љ
O
O
S
P
—
—
—
—
—
—
—
—
1.77 (E4)
— (E5)
— (E4)
1.77 (E5)
0.64 (E4)
2.84 (E5)
1.57 (E4)
4.97 (E5)
2.50 (E4)
8.25 (E5)
As
P
2.84 (E4)
0.64 (E5)
4.97 (E4)
1.57 (E5)
8.25 (E4)
2.50 (E5)
Fig. 4 Non-bonding attraction due to (a) the nE→σ*MC and (b)
nE→σ*MS interactions in (CH3CES)M(CH3)2 (E = O or S; M = P or As)
and (c) the nE5→σ*MS3 and (d) nE5→σ*MS2 interactions in (CH3CES)2-
MCH3 (E = O or S; M = P or As).
S
As
a Stabilization energy associated with delocalization.
the n orbital (nO) on the carbonyl oxygen and the σ*MC orbitals
in 1Ј and 2Ј (Fig. 4a) are present, but their values are close to
each other (Table 2). Interactions between the nS and σ*MS
orbitals (Fig. 4b) are also appreciable for 1Љ and 2Љ together
with interactions between the nS and σ*MC orbitals. The contour
(see Figs. 1b and 2b). The atomic charges (0.73) of the As in the
arsenic compounds (2Ј, 2Љ, 4Ј and 4Љ) are larger than those in
the phosphorus compounds (0.63 for 1Ј and 1; 0.53 for 3Ј and
3Љ), suggesting that electrostatic interactions may contribute to
maps of the nE and σ*MS orbitals in the molecular plane C(᎐S)–
᎐
S–M (E = O or S; M = P or S) for the model compounds were
depicted by using the MOLDEN 3.6 program.14 Indeed, the
overlaps between the nS and σ*MS orbitals are present for 1Љ
and 2Љ.
the short C᎐E ؒ ؒ ؒ As distances.
᎐
Spectra
In the case of the bis derivatives (3Ј, 3Љ, 4Ј and 4Љ) the inter-
actions between the n orbitals (nE) on the carbonyl oxygen or
thiocarbonyl sulfur and σ*MC are absent. Instead, the orbital
interactions between nE5 and σ*MS3 and between nE4 and σ*MS2
(Fig. 4c) are large. Those between nE5 and σ*MS2 and between
nE4 and σ*MS3 (Fig. 4d) are also appreciable for 4Ј, 3Љ and 4Љ, but
small. The contour maps of the nE and σ*MS orbitals in the
In Table 3 the thiocarbonyl and carbonyl stretching frequencies,
thiocarbonyl and carbonyl carbon chemical shifts and the vis-
ible spectral data are collected. It is noted that the thiocarbonyl
stretching frequencies of compounds 3–5 appear at 1170–1250
cmϪ1. The carbonyl stretching frequencies for 6–8 are observed
at 1610–1690 cmϪ1 and show a low frequency shift in the order
7 < 8 < 6, which is consistent with the C᎐O ؒ ؒ ؒ As distance.
᎐
molecular planes C(᎐E)–S–M–S–C(᎐E) (E = O or S; M = P or
᎐
᎐
The thiocarbonyl carbon chemical shifts of 4 and 5 are
observed in the region δ 214–257, and those of 3 show an
upfield shift of 3–5 ppm compared with those of 4 and 5. The
carbonyl carbon chemical shifts of 6–8 appear at δ 190–208,
and that of the t-C4H9 derivative 6b shows a downfield shift
relative to those of the other derivatives. In the electronic
spectra the absorptions of 4 due to the n–π* transitions of the
As) for 4Ј, 3Љ and 4Љ obtained by using the MOLDEN 3.6 pro-
gram14 showed the expected overlaps between the nE and σ*MS
orbitals. The stabilization energies of the arsenic compounds 2Ј,
2Љ, 4Ј and 4Љ are larger than those of the corresponding phos-
phorus compounds 1Ј, 1Љ, 3Ј and 3Љ, respectively. In addition,
the stabilization energies of the dithiocarboxylic acid deriv-
atives 1Љ–4Љ are greater than those of the corresponding thio-
carboxylic acid derivatives 1Ј–4Ј, respectively. The former
tendency may be understood in the terms of their orbital levels:
the lower energy level of the σ*AsS orbitals compared with that
of σ*PS. Also, the latter can also be understood in terms of the
lower energy level of the nO orbitals (Ϫ0.93201, Ϫ0.46778 au for
2Ј; Ϫ0.94975, Ϫ0.48359 au for 2Љ) compared with that of the nS
orbitals (Ϫ0.66262, Ϫ0.31594 au for 4Ј; Ϫ0.67753, Ϫ0.33772 au
for 4Љ). These non-bonding orbital interactions between nE
and σ*MS in the bis derivatives 4 and 7 may facilitate the two
dithio- or thio-carboxylate groups being in the same direction
C᎐S group show hypsochromic shifts compared with those of
᎐
the mono 3 and tris derivatives 5.
Reactions of compounds 3–5 or 6–8 with piperidine
Expecting formation of a piperidinium diphenylthioarsenate()
salt (H2NC5H10)ϩPh2AsSϪ, the reactions of (4-methylthio-
benzoylsulfanyl)diphenyl- 3e and (4-methylbenzoylsulfanyl)-
diphenyl-arsine 6e with piperidine were examined (Table 4).
When 3e or 6e and two equivalents of piperidine were
refluxed in ethanol, piperidinium diphenyldithioarsinate 9 was
J. Chem. Soc., Dalton Trans., 2001, 518–527
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Table 3 Spectral data of compounds 3, 4, 5, 6, 7 and 8
ν(C᎐S)a/cmϪ1
δC᎐S
λmax c/nm
mono 3
b
᎐
(RCS2)xAsPh3 Ϫ x
R
mono 3
bis 4
tris 5
mono 3
bis 4
tris 5
bis 4
tris 5
C6H5
1218
1227
1264
1224
1238
1238
1241
1265
1237
1227
1241
1243
1249
1241
1229
229.0
227.8
226.2
227.0
233.4
231.0
230.3
228.1
228.9
235.4
234.2
234.1
231.0
232.7
239.3
527
527
518
533
494
506
505
498
507
495
511
511
505
510
500
4-CH3C6H4
4-CH3OC6H4
4-ClC6H4
1-Naph
ν(C᎐O)a/cmϪ1
δC᎐O
b
᎐
(RCOS)xAsPh3 Ϫ x
R
mono 6
bis 7
tris 8
mono 6
bis 7
tris 8
C6H5
1644
1644
1629
1655
1639
1626
1628
1612
1631
1639
1627
1660
192.1
191.7
190.5
190.8
192.8
192.4
191.1
191.6
190.3
192.5
191.3
191.7
4-CH3C6H4
4-CH3OC6H4
4-ClC6H4
a As KBr disc. b In CDCl3. c In CH2Cl2.
Table 4 Reactions of 3e and 6e with piperidine
Yieldb (%)
4e or 7e:
Entry
Compound
piperidinea
t/h
T/ЊC
9
10
11
13
1
2
3
4
5
3e
3e
6e
6e
6e
1:1
1:2
1:1
1:1
1:2
9
9
3
12
12
20
78
20
20
78
7
38
5
10
42
44 (10-S)
69 (10-S)
83 (10-O)
90 (10-O)
88 (10-O)
31 (11-S)
0
0
0
0
11
0 (11-S)
17 (11-O)
0 (11-O)
0 (11-O)
a Mole ratio. b Isolated yields.
obtained in yields of 38 and 42%, respectively, together
with N-4-methylthiobenzoylpiperidine 10-S or N-4-methyl-
benzoylpiperidine 10-O (entries 2 and 5). The reaction with an
equivalent of piperidine in EtOH at 20 ЊC resulted in a sig-
nificant decrease in 9. Instead, the corresponding thioamide
10-S or amide 10-O was obtained in good yields along with
11-S or 11-O (entries 1 and 3). A plausible mechanism for the
formation of 9 is shown in Scheme 2, where piperidine attacks
the thiocarbonyl or carbonyl carbon in 3e and 6e to form
piperidinium diphenylthioarsenate salt 12, which further dispro-
portionates to give 9 and tetraphenyldiarsane, while piperidine
attacks the As to form dithio- or thio-carboxylic acids which
further react with piperidine to give 11-S and 11-O. We have
observed that 11-S5a,b and 11-O16 gradually decompose at room
temperature to 10-S and 10-O, respectively, with the evolution
of hydrogen sulfide.
In contrast to the results with compounds 3e and 6e, the
reaction of bis(4-methylthiobenzoylsulfanyl)phenylarsine 4e
under the same conditions gave di(piperidinium) phenyltri-
thioarsonate 15 in 14% yield along with 10-S (Table 5, entry 1).
The reaction with four equivalents of piperidine at 78 ЊC in
ethanol led to a significant increase in the yield of 15 (entry 3).
Formation of 11-S was not observed. On the other hand, reflux
Scheme 2
of 7e and two equivalents of piperidine in ethanol gave 2,4,6,8-
tetraphenyl-1,3,5,7,2,4,6,8-tetrathiatetrarsocane 1417 (here-
after called cyclic tetramer) and 11-O in 63 and 27% yields,
522
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Table 5 Reactions of compounds 4e and 7e with piperidine
Yieldb (%)
4e or 7e:
Entry
Compound
piperidinea
t/h
T/ЊC
10
11
0 (11-S)
0 (11-S)
0 (11-S)
14
15
1
2
3
4
5
4e
4e
4e
7e
7e
1:2
1:2
1:4
1:2
1:2
5
2
5
15
3
20
78
78
78
20
35 (10-S)
38 (10-S)
84 (10-S)
70 (10-O)
56 (10-O)
0
4
16
63
66
14
24
65
0
27 (11-O)
40 (11-O)
0
a Mole ratio. b Isolated yields.
respectively (entry 4). The reactions at room temperature led to
a decrease in 10-O and to an increase in 11-O (entry 5). One
plausible mechanism for the formation of 14 and 15 is shown in
Scheme 3, where piperidine attacks initially at the thiocarbonyl
Scheme 4
traces of a white solid with mp >300 ЊC and a slightly yellow
solid 20 with mp 142–145 ЊC (Scheme 5). The structure of
Scheme 5
20 was deduced as (H2NC5H10ϩ)2(As2S6)2Ϫ on the basis of
1
elemental analysis and the IR and H NMR spectra which
show characteristic absorption bands of piperidinium salts as
observed for 9 and 15.
Structures of salts 9 and 15 and the cyclic tetramer (PhAsS)4 14
The ORTEP drawings of the salts 9 and 15 are shown in Fig. 5a
and b, respectively. The structure determined for 9 shows that it
exists as a dimer in the solid state, in which the distances
S(1) ؒ ؒ ؒ N(1*) 3.225(3) and S(2) ؒ ؒ ؒ N(1) 3.473(3) Å are close to
the sum of the van der Waals radii of both atoms (3.26 Å),11
clearly indicative of the presence of N–H ؒ ؒ ؒ S hydrogen
bonding between the molecules. In the dimer a 12-membered
ring is formed by the hydrogen bonding (Fig. 5a). The two
As–S bond lengths (As(1)–S(1) 2.128(1), As(1)–S(2) 2.101(1)
Å) are intermediate between the sum of their single (2.25
Å)18 and double-bond covalent bond radii (2.05 Å),18 suggest-
ing delocalization of the negative charge on the AsS2 moiety
of 9. The angles around the As atom (103.3(1)–116.27(4)Њ)
are close to tetrahedral, thus yielding a distorted tetrahedral
structure.
Scheme 3
carbon in 4e or carbonyl carbon in 7e to form 10-S or 10-O and
unstable piperidinium salts 16 (E = S or O), respectively. In the
case of dithiocarboxylic acid derivative 4e the thiocarbonyl
carbon is further attacked by piperidine to form the dithio-
arsenate dianion 17 which disproportionates to give 15 and
phenylthioxoarsine 18 which further tetramerizes to give 14
(path a). In this reaction, the formation of a cyclic trimer of 18
was not observed. In the case of the thiocarboxylic acid deriv-
ative 7e the As–S bond of 16 (E = O) is cleaved to give 11-O
and 18 (path b). The processes for the disproportionation of 17
to give 15 and for tetramerization of 18 to 14 are not clear at
this time. The structures of 9, 14 and 15 were determined by 1H
and 13C NMR, elemental analysis and and by X-ray structural
analysis. In addition, 15 was converted into 4-bromophenacyl
ester 19 (Scheme 4).
In compound 15 the three As–S bond distances are in the
range 2.135(3)–2.151(2) Å, indicative of their covalent radii
having values intermediate between those of single and double
bonds,18 and suggesting delocalization of the negative charges
on the AsS3 group. The bond angles around the central As atom
are S(1)–As(1)–S(2) 111.69(9), S(1)–As(1)–C(1) 105.8(2), S(1)–
The reaction of tris(4-methylthiobenzoylsulfanyl)arsine 5e
with piperidine under reflux in ethanol gave 10-S along with
J. Chem. Soc., Dalton Trans., 2001, 518–527
523

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Fig.
6 Molecular structure of 2,4,6,8-tetraphenyl-1,3,5,7,2,4,6,8-
tetrathiatetrarsocane 14. Details as in Fig. 1.
Center of Kyoto University and Bernhardt Analytisch
Laboratorium.
Materials
All solvents were dried and distilled prior to use. Arsenic()
chloride was obtained from Aldrich. Chlorodiphenylarsine21
and dichlorophenylarsine22 were prepared by heating tri-
phenylarsine23 with arsenic() chloride under argon at 250 ЊC
for 5–10 h. Piperidinium carbodithioates5b and potassium
carbothioates24 were prepared according to the literature
procedures. Piperidine and 4-bromophenacyl bromide were
commercial grade.
X-Ray crystallography
Measurements were carried out on a Rigaku AFC7R four-
circle diffractometer with graphite-monochromated Mo-Kα
radiation (λ = 0.71069 Å). All the structures were solved and
refined using the TEXSAN crystallographic software pack-
age.25 All crystal samples were cut from the grown crystals,
mounted on a glass fiber, and coated with an epoxy resin.
Lorentz and polarization corrections were applied to the
data, and empirical absorption corrections [Ψ scans26 (3g, 4e,
5e, 6h, 7g, 8e or 14) and DIFABS27 (9 or 15)] were also
applied. The structures were solved by direct methods using
SHELXS 8626 for 3g, 6h, 7g, 9, 14 or 15, SAPI9128 for 4e or
8e and MITHRIL 9029 for 5e and expanded using DIRDIF,
94.30 Scattering factors for neutral atoms were from Cromer
and Waber31 and anomalous dispersion32 was used. A full-
matrix least-squares refinement was executed, with non-
hydrogen atoms being anisotropic for 3g, 4e, 5e, 6h, 7g, 8e, 9,
14 or 15, and using SHELXL 93 for 8e.33 The final least-
squares cycle included fixed hydrogen atoms at calculated
positions, for which each isotropic thermal parameter was set
to 1.2 times that of the connecting atoms. Crystal data and
data collection parameters are summarized in Table 6. The
bond lengths and angles and torsion angles are deposited as
ESI supplementary data.
Fig. 5 Molecular structures of (a) piperidinium diphenyldithio-
arsinate 9 and (b) di(piperidinium) phenyltrithioarsonate 15. Details
as in Fig. 1.
As(1)–S(3) 112.0(1), S(2)–As(1)–C(1) 106.7(2), S(2)–As(1)–S(3)
113.6(1) and S(3)–As(1)–C(1) 106.5(2)Њ, indicating a distorted
tetrahedron. As in 9, the distances between S and N (3.195(8)–
3.339(8) Å) of 15 are close to the sum of their van der Waals
radii (3.35 Å), indicating the presence of N–H ؒ ؒ ؒ S inter-
molecular hydrogen bonding.11 Thus, 15 exists as a polymer in
which a 12-membered ring was formed by the hydrogen bond-
ing (Fig. 5b) and is the first example of an organoarsenic
trithionate in which two negative charges are delocalized on the
AsS3 moiety.
The ORTEP drawing of cyclic tetramer 14 is shown in Fig. 6.
The crown ring structure is similar to that of the tetramer
(PhAsS)4 prepared by treating phenylarsine with thionyl
chloride,19 and closely resembles those in the analogous methyl
cyclo-tetramer20 and cyclo-S8.
Preparation of single crystals at 25 ЊC. Compound 3g (0.060
g) from dichloromethane (1.5 mL) and hexane (1.1 mL) for 8
days, 4e (0.130 g) from dichloromethane (1.0 mL) and hexane
(0.6 mL) for 6 days, 5e (0.095 g) from dichloromethane (4.3 mL)
and hexane (3.0 mL) for 6 days, 6h (0.090 g) from dichloro-
methane (2.0 mL) and hexane (2.0 mL) for 4 days, 7g (0.140 g)
from dichloromethane (1.5 mL) and hexane (1.1 mL) for
1 week, 8e (0.070 g) from dichloromethane (0.5 mL) and
hexane (2.8 mL) for 4 days, 9 (0.035 g) from dichloromethane
(3.5 mL) and hexane (2.8 mL) for 1 week, 14 (0.032 g) from
dichloromethane (0.5 mL) and hexane (0.7 mL) for 3 days and
15 (0.051 g) from dichloromethane (1.5 mL) and hexane (3.0
mL) for 5 days.
Experimental
General
Melting points were determined by a Yanagimoto micromelting
point apparatus and are uncorrected. The IR spectra were
measured on JASCO grating IR-G and Perkin-Elmer FT-IR
1640 spectrophotometers, 1H (400 MHz) and 13C NMR spectra
(100 MHz) on JEOL JNM-α400 spectrometers in CDCl3
1
containing Me4Si as an internal standard, the H spectrum
(60 MHz) of compound 19 on a Hitachi R-24 and UV and
visible spectra on Hitachi 124 and 330 spectrophotometers.
Elemental analyses were performed by the Elemental Analysis
CCDC reference number 186/2321.
See http://www.rsc.org/suppdata/dt/b0/b008702p/ for crystal-
lographic files in .cif format.
524
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Syntheses of thioacylsulfanyl- 3–5 and acylsulfanyl-arsines 6–8
Typical procedures are described in detail for the preparation of
compounds 3e and 6e. Spectroscopic data of other thioacyl-
sulfanyl 3–5 and acylsulfanyl-arsines 6–8 are deposited as ESI
supplementary data.
(4-Methylthiobenzoylsulfanyl)diphenylarsine 3e. To a solution
of piperidinium 4-methylbenzenecarbodithioate (0.269 g, 1.06
mmol) in CH2Cl2 (15 mL) was added Ph2AsCl (0.264 g, 1.00
mmol) in CH2Cl2 (5 mL), and the mixture stirred at 20 ЊC for
1 h. After addition of CH2Cl2 (100 mL), the mixture was
washed with water (3 × 90 mL), followed by drying over MgSO4
(ca. 2 g) for 1 h. The solvent was removed under reduced pres-
sure by use of a rotary evaporator (30 ЊC/2.7 kPa). The resulting
residue was dissolved in diethyl ether (5 mL), and allowed to
stand in a refrigerator (Ϫ20 ЊC) for 24 h to give compound 3e as
red crystals 0.358 g (91%), mp 85–87 ЊC (Calc. for C20H17AsS2:
C, 60.60; H, 4.32. Found: C, 60.50; H, 4.36%). νmax/cmϪ1 (C᎐S)
᎐
1227 (KBr); λmax/nm (CH2Cl2) 330 (ε/dm3 molϪ1 cmϪ1 17 000)
and 527 (170); δH(CDCl3) 2.22 (s, 3H, CH3), 7.03 (d, J = 8.1,
2H), 7.24–7.27 (m, 6H), 7.49–7.53 (m, 4H) and 8.06 (d, J = 8.1
Hz, 2H); δC(CDCl3) 21.4 (CH3), 127.1, 128.6, 128.6, 129.2,
133.0, 137.9, 141.9, 143.6 and 227.8 (C᎐S).
᎐
(4-Methylbenzoylsulfanyl)diphenylarsine 6e. To a solution of
Ph2AsCl (0.271 g, 1.02 mmol) in CH2Cl2 (20 mL), potassium
4-methylbenzenecarbothioate (0.196 g, 1.03 mmol) was added
and the mixture stirred at 20 ЊC for 1 h. After addition of
CH2Cl2 (100 mL), the mixture was washed with water (3 × 90
mL), followed by drying over MgSO4 (ca. 2 g) for 1 h. The
solvents were removed under reduced pressure by use of a
rotary evaporator (30 ЊC/2.7 kPa). The resulting residue was
dissolved in CH2Cl2 (10 mL) and hexane (10 mL) and allowed
to stand in a refrigerator (Ϫ20 ЊC) for 24 h to give compound 6e
as colorless crystals (0.358 g, 92%), mp 96–99 ЊC (Calc. for
C20H17AsOS: C, 63.16; H, 4.51. Found: C, 62.95; H, 4.61%).
νmax/cmϪ1 (C᎐O) 1644 (KBr); δ (CDCl ) 2.39 (s, 3H, CH ), 7.21
᎐
H
3
3
(d, J = 8.1, 2H), 7.34–7.38 (m, 6H), 7.56–7.60 (m, 4H) and 7.94
(d, J = 8.1 Hz, 2H); δC(CDCl3) 21.7 (CH3), 128.4, 128.8, 129.2,
129.4, 133.2, 134.8, 138.5, 144.5 and 191.7 (C᎐O).
᎐
Reaction of compound 3e with piperidine (Table 4, entry 2)
A suspension of compound 3e (0.198 g, 0.50 mmol) in ethanol
(40 mL) was added dropwise to a solution of piperidine (0.085
g, 1.00 mmol) in ethanol (20 mL). This suspension was stirred
at 78 ЊC for 9 h. The solvent was evaporated under reduced
pressure (20 ЊC/53 Pa), followed by addition of ether (20 mL).
Filtration of the resulting precipitates gave piperidinium
diphenyldithioarsinate 9 as colorless needles (0.072 g, 38%).
N-4-Methylthiobenzoylpiperidine 10-S was obtained from this
1
filtrate as yellow crystals (0.076 g, 69%). H and 13C NMR
spectra were exactly consistent with those of authentic samples
prepared by heating piperidinium 4-methylbenzenecarbo-
dithioate. Piperidinium diphenyldithioarsinate 9: mp 155–
157 ЊC (Calc. for C17H22AsNS2: C, 53.82; H, 5.84; N, 3.69.
Found: C, 53.44; H, 5.70; N, 3.82%); νmax/cmϪ1 3014, 2885,
1603, 1609, 1491, 1456, 1410, 1324, 1178, 1098, 1043, 1019, 961,
948, 881, 772, 718 and 699 (KBr); δH(CDCl3) 1.41–1.46 (m,
2H), 1.60–1.66 (m, 4H), 3.04–3.06 (m, 4H), 7.33–7.41 (m, 6H),
8.04–8.06 (m, 4H) and 9.02 (br, 2H, NH2); δC(CDCl3) 22.3,
22.5, 44.2, 128.4, 129.7, 130.0 and 143.5.
Reaction of compound 6e with piperidine (Table 4, entry 3)
A suspension of compound 6e (0.380 g, 1.00 mmol) in ethanol
(40 mL) was added dropwise to a solution of piperidine (0.086
g, 1.01 mmol) in ethanol (20 mL). This suspension was stirred
at 20 ЊC for 3 h. The solvent was evaporated under reduced
pressure (20 ЊC/53 Pa), followed by addition of ether (20 mL).
J. Chem. Soc., Dalton Trans., 2001, 518–527
525

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Filtration of the resulting precipitates gave piperidinium
4-methylbenzenecarbothioate 11-O as a colorless solid (0.040 g,
17%). To the filtrate was added toluene (10 mL) and the mixture
allowed to stand in a refrigerator (Ϫ20 ЊC) for 48 h. Filtration
of the resulting precipitate gave 9 as colorless needles (0.019 g,
5%). N-4-Methylbenzoylpiperidine 10-O was obtained from
this filtrate as a colorless oil (0.168 g, 83%).
from the filtrate was removed under reduced pressure. To the
residue ether (30 mL) was added. Filtration of the ether insol-
uble part gave 0.088 g of a slightly yellow solid 20 [mp 142–
145 ЊC (decomp.) (Calc. for C10H24As2N2S8: C, 20.76; H, 4.18;
N, 4.84. Found: C, 20.43; H, 4.06; N, 4.92%); δH (DMSO-d6)
1.1–3.2. Removal of the ether from the filtrate under reduced
pressure gave 10-S in 48% yield.
Reaction of compound 4e with piperidine (Table 5, entry 1)
Acknowledgements
A suspension of compound 4e (0.487 g, 1.00 mmol) in ethanol
(80 mL) was added dropwise to a solution of piperidine (0.173
g, 2.03 mmol) in ethanol (40 mL), and this suspension was
stirred at 20 ЊC for 5 h. The solvent was evaporated under
reduced pressure (20 ЊC/53 Pa), followed by addition of ether
(20 mL). Filtration of the resulting precipitate gave di(piper-
idinium) phenyltrithioarsonate 15 as a colorless solid (0.057 g,
14%). Evaporation of the filtrate under reduced pressure gave
10-S (0.149 g, 35%). Di(piperidinium) phenyltrithioarsonate
15: mp 154–157 ЊC (Calc. for C16H29AsN2S3: C, 45.70; H, 6.95;
N, 6.66. Found: C, 45.54; H, 6.87; N, 6.51%); νmax/cmϪ1 2950,
2710, 2500, 1579, 1455, 1441, 1308, 1078, 1039, 938, 872, 754,
703 and 651 (KBr); δH(CDCl3) 1.59–1.65 (m, 4H), 1.82–1.88
(m, 8H), 3.23–3.25 (m, 8H), 7.33–7.35 (m, 3H), 7.42–7.44
(m, 2H) and 8.23 (br, 4H, NH2); δC (CDCl3) 22.6, 22.9, 44.8,
128.3, 129.8, 131.0 and 133.0.
This research was supported by a Grant-in-Aid for Scientific
Research on Priority Areas (No. 09239220) and by Grant-
in-Aid for Scientific Research (No. 09355032) from the
Ministry of Education, Science, Sports and Culture of
Japan. We thank Professor Takashi Kawamura and Associate
Professor Masahiro Ebihara of Gifu University for their
invaluable assistance with X-ray crystallography.
References
1 Reviews: (a) D. Coucouvanis, Prog. Inorg. Chem., 1970, 11, 301;
D. Coucouvanis, Prog. Inorg. Chem., 1979, 26, 301; (b) I. Haiduc,
Rev. Inorg. Chem., 1981, 3, 353. Articles after 1981: (c) T. Ito and
H. Hishino, Acta Crystallogr., Sect. C, 1983, 39, 448; (d) B. F.
Hoskins, P. M. Piko, E. R. T. Tiekink and G. Winter, Inorg. Chim.
Acta, 1984, 84, L13; (e) B. F. Hoskins, E. R. T. Tiekink and
G. Winter, Inorg. Chim. Acta, 1985, 99, 177; ( f ) N. R. Snow
and E. R. T. Tiekink, Aust. J. Chem., 1987, 40, 743; (g) R.
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2 (CH3COS)AsPhEt: G. M. Usacheva and G. Kh. Kami, Russ. J. Gen.
Chem., 1970, 40, 1298; G. M. Usacheva and G. Kh. Kami, Izv. Akad.
Nauk SSSR., Ser. Khim., 1968, 1878. (CH3COS)2AsCH3, (PhCOS)2-
AsCH3, (PhCOS)2AsPh, (4-ClC6H4COS)2AsCH3, (4-ClC6H4-
COS)AsPh2 and (C6Cl5COS)2AsMe: E. Urbschat and P. E.
Frohberger, US Pat., 2 767 114, 1956; Chem. Abstr., 1957, 51, 5354c.
3 (PhCS2)3As and (4-BrC6H4CS2)3As: J. Houben, Ber. Dtsch. Chem.
Ges., 1906, 39, 3219.
Reaction of compound 7e with piperidine (Table 5, entry 5)
A suspension of compound 7e (0.454 g, 1.00 mmol) in ethanol
(80 mL) was added dropwise to a solution of piperidine (0.173
g, 2.03 mmol) in ethanol (40 mL), and this suspension was
stirred at 20 ЊC for 3 h. The solvent was evaporated under
reduced pressure (20 ЊC/53 Pa), followed by addition of ether
(20 mL). Filtration of the resulting precipitate gave 11-O as a
colorless solid (0.190 g, 40%). The filtrate was added to ethanol
(20 mL), and filtration of the resulting precipitate gave 0.162 g
(66%) of 2,4,6,8-tetraphenyl-1,3,5,7,2,4,6,8-tetrathiatetrarso-
cane 14 as a colorless solid which was recrystallized from
dichloromethane–hexane. The compound 10-O was obtained
from this filtrate as a colorless oil (0.227 g, 56%). 2,4,6,8-
Tetraphenyl-1,3,5,7,2,4,6,8-tetrathiatetrarsocane 14: mp 174–
175 ЊC (lit.,20 175–176 ЊC) (Calc. for C24H20As4S4: C, 39.15; H,
2.74. Found: C, 39.32; H, 2.66%); νmax/cmϪ1 3042, 1571, 1475,
1429, 1179, 1062, 1019, 998, 728, 687 and 468 (KBr); δH(CDCl3)
7.34–7.45 (m, 12H) and 7.77–7.87 (m, 8H); δC(CDCl3) 129.0,
130.0, 131.6 and 142.3.
4 To our knowledge, such R2AsSϪ species have not been reported.
5 For example, ammonium dithiocarboxylates: (a) S. Kato and
M. Mizuta, Bull. Chem. Soc. Jpn., 1972, 45, 3492; (b) S. Kato,
T. Mitani and M. Mizuta, Int. J. Sulfur Chem., Part A, 1973, 8, 359;
(c) S. Kato, S. Chiba, M. Mizuta and M. Ishida, Z. Naturforsch.,
Teil B, 1982, 37, 736. Alkali metal dithiocarboxylates: S. Kato,
K. Ito, R. Hattori, M. Mizuta and T. Katada, Z. Naturforsch.,
Teil B, 1978, 33, 976; S. Kato, S. Yamada, H. Goto, K. Terashima,
M. Mizuta and T. Katada, Z. Naturforsch., Teil B, 1980, 35, 458;
S. Kato, N. Kitaoka, O. Niyomura, Y. Kitoh, T. Kanda and
M. Ebihara, Inorg. Chem., 1999, 38, 495.
6 [(RCEEЈ)xMRЈ4 Ϫ x, x = 1 or 2, E, EЈ = O, S, Se or Te; M = C, Si,
Ge, Sn or Pb]: S. Kato, W. Akada, M. Mizuta and Y. Ishii, Bull.
Chem. Soc. Jpn., 1973, 46, 244; S. Kato, M. Mizuta and Y. Ishii,
J. Organomet. Chem., 1973, 55, 121; S. Kato, A. Hori, H. Shiotani,
M. Mizuta, N. Hayashi and T. Takakuwa, J. Organomet. Chem.,
1974, 82, 223; T. Katada, S. Kato and M. Mizuta, Chem. Lett., 1975,
1037; S. Kato, A. Hori, M. Mizuta, T. Katada and H. Ishihara,
J. Organomet. Chem., 1991, 420, 13; S. Kato, H. Kageyama,
Y. Kawahara, T. Murai and H. Ishihara, Chem. Ber., 1992, 125, 417;
S. Kato, T. Komuro, T. Kanda, H. Ishihara and T. Murai, J. Am.
Chem. Soc., 1993, 115, 3000; H. Kageyama, K. Kido, S. Kato and
T. Murai, J. Chem. Soc., Perkin Trans. 1, 1994, 1083. (RCSS)PPh2:
S. Kato, M. Goto, R. Hattori, K. Nishiwaki, M. Mizuta and
M. Ishida, Chem. Ber., 1985, 118, 1668. (RCSS)2E (E = Se or Te):
S. Kato, Y. Itoh, Y. Ohta, M. Kimura, M. Mizuta and T. Murai,
Chem. Ber., 1985, 118, 1696. RCOSX (X = Cl, Br or I): S. Kato,
E. Hattori, M. Mizuta and M. Ishida, Angew. Chem., Int. Ed. Engl.,
1982, 21, 150; S. Kato, K. Miyagawa, S. Kawabata and M. Ishida,
Synthesis, 1982, 1013; S. Kato, K. Itoh, K. Miyagawa and
M. Ishida, Synthesis, 1983, 814. (RCOE)2 (E = S, Se or Te): O.
Niyomura, S. Kato and S. Inagaki, J. Am. Chem. Soc., 2000, 122,
2132.
Reaction of di(piperidinium) phenyltrithioarsonate 15 with
4-bromophenacyl bromide (Scheme 4)
A two molar amount of 4-bromophenacyl bromide (0.139 g,
0.50 mmol) in ethanol (5.0 mL) was added to a suspension of
compound 15 (0.105 g, 0.25 mmol) in ethanol (20 mL) and
refluxed for 10 min. The solvent was evaporated and ether (50
mL) added, followed by washing with water (3 × 90 mL) and
drying over Na2SO4 (ca. 2 g) for 1 h. The solvents were removed
under reduced pressure by use of a rotary evaporator (30 ЊC/2.7
kPa). The resulting residue was dissolved in CH2Cl2 (2.0 mL)
and hexane (0.5 mL) and allowed to stand in a refrigerator
(Ϫ20 ЊC) for 24 h to give di(4-bromophenacyl) phenyltrithio-
arsonate 19 as colorless crystals (0.027 g, 18%): mp 134–137 ЊC
(Calc. for C22H17AsBr2O2S3: C, 41.01; H, 2.66. Found: C, 41.35;
H, 2.66%); νmax/cmϪ1 (C᎐O) 1685 (KBr); δ (CDCl ) 4.1 (s, 4H,
᎐
H
3
CH2) and 7.2–8.0 (m, 13H).
Reaction of compound 5e with piperidine (Scheme 5)
Tris(4-methylthiobenzoylsulfanyl)arsine 5e (0.288 g, 0.50
mmol) and piperidine (0.128 g, 1.50 mmol) were refluxed in
ethanol (50 mL) for 3 h. Filtration of the precipitates gave
0.006 g of a white solid (mp >300 ЊC) (AsxSy?). The ethanol
7 T. Kanda, K. Mizoguchi, T. Koike, T. Murai and S. Kato, Synthesis,
1994, 282.
8 T. Kanda, K. Mizoguchi, S. Kagohashi and S. Kato,
Organometallics, 1998, 17, 1487.
526
J. Chem. Soc., Dalton Trans., 2001, 518–527

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9 P. Singh, S. Singh, V. D. Gupta and H. Nöth, Z. Naturforsch., Teil B,
1998, 53, 1475.
22 G. O. Doak and L. D. Freeman, in Organometallic Compounds
of Arsenic, Antimony and Bismuth, Wiley Sons Press,
&
10 Unpublished results. (a) [(RCS2)xAsPh3 Ϫ x, x = 1–3]: S. Hanabusa,
New York, 1970, p. 84; M. Dub, in Organometallic Compounds,
Springer-Verlag Press, New York, 2nd edn., 1968, vol. III,
pp. 165–182.
Master’s Thesis, Gifu University, 1983 (Engl.); (b) S. Suzuki,
Undergraduate Thesis, Gifu University, 1979; (c) (RCOS)xAsPh3 Ϫ x
x = 1–3]: S. Mutoh, Undergraduate Thesis, Gifu University, 1985.
,
23 Triphenylarsine was prepared by treating PhMgBr with AsCl3 in
tetrahydrofuran: L. Pheiffer and W. Pietsch, Ber. Dtsch. Chem. Ges.,
1904, 37, 4621.
11 A. Bondi, J. Phys. Chem., 1964, 68, 441. van der Waals distances:
As ؒ ؒ ؒ S 3.65, As ؒ ؒ ؒ O 3.36, N ؒ ؒ ؒ S 3.26 Å.
12 C. K. Johnson, ORTEP II, Report ORNL-5138, Oak Ridge
National Laboratory, Oak Ridge, TN, 1976.
13 K. Tani, K. Matsuyama, S. Kato, K. Yamada and H. Mifune, Bull.
Chem. Soc. Jpn., 2000, 73, 1243.
14 G. Schaftenaar and J. H. Noordik, J. Comput.-Aided Mol. Des.,
2000, 14, 123.
15 M. J. Frisch, G. W. Trucks, H. B. Schlegel, P. M. W. Gill, B. G.
Johnson, M. A. Robb, J. R. Cheeseman, T. Keith, G. E. Petersson,
J. A. Montgomery, K. Raghavachari, M. A. Al-Laham, V. G.
Zakrzewski, J. V. Ortiz, J. B. Foresman, J. Cioslowski, B. B.
Stefanov, A. Nanayakkara, M. Challacombe, C. Y. Peng, P. Y.
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