New P-S-N containing ring systems. Reaction of 2,4-(naphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide and its 4-methoxynaphthalene derivative with hexamethyldisilazane

Article abstract of DOI:10.1039/a708348c

Reaction of 2,4-(naphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide 1 with hexamethyldisilazane (hmds) in acetonitrile gave the N,N′-bis(trimethylsilyl)acetamidinium salt of the [(C₁₀H₆)P(S)(NHSiMe₃)SP(S)₂] ^- anion 2, a product of P₂S₂ ring cleavage, together with the new thiazaphosphetidine (C₁₀H₆)P(S)SN(SiMe₃)P(S) 3. Analogous (methoxy derived) products to 2 (2a, 2b) and 3 (3a) were obtained when 2,4-(4-methoxynaphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide 1a was used instead of 1. When the reaction of 1 with hmds was performed in dichloromethane a mixture of the products was obtained, from which the hexamethyldisilazan-2-ium salt of the anion of identical structure to that in 2 has been isolated. No reaction occurred when a solventless system was used. The new compounds were studied spectroscopically (one- and two-dimensional NMR, IR spectroscopy) and by X-ray crystallography (3, 3a and 4).

Full text of DOI:10.1039/a708348c

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New P᎐S᎐N containing ring systems. Reaction of 2,4-(naphthalene-
,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide and its 4-methoxy-
naphthalene derivative with hexamethyldisilazane
1
,
,a
a
b
a
b
a
Petr Kilián,* † Jaromír Marek, Radek Marek, Jiøí Touؒín, Otakar Humpa, Josef Novosad
,
,c
and J. Derek Woollins* ‡
a
Department of Inorganic Chemistry, Masaryk University, Kotláøská 2, Brno 611 37,
Czech Republic
b
NMR Laboratory, Faculty of Science, Masaryk University, Kotláøká 2, Brno 611 37,
Czech Republic
c
Department of Chemistry, Loughborough University, Loughborough, Leics, UK LE11 3TU
Reaction of 2,4-(naphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide 1 with hexamethyldisilazane
hmds) in acetonitrile gave the N,NЈ-bis(trimethylsilyl)acetamidinium salt of the [(C H )P(S)(NHSiMe )SP(S) ]
Ϫ
(
10
6
3
2
anion 2, a product of P S ring cleavage, together with the new thiazaphosphetidine (C H )P(S)SN(SiMe )P(S) 3.
2
2
10
6
3
Analogous (methoxy derived) products to 2 (2a, 2b) and 3 (3a) were obtained when 2,4-(4-methoxynaphthalene-
,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide 1a was used instead of 1. When the reaction of 1 with hmds
was performed in dichloromethane a mixture of the products was obtained, from which the hexamethyldisilazan-
-ium salt of the anion of identical structure to that in 2 has been isolated. No reaction occurred when a
1
2
solventless system was used. The new compounds were studied spectroscopically (one- and two-dimensional
NMR, IR spectroscopy) and by X-ray crystallography (3, 3a and 4).
Compounds with the P S heterocyclic system continue to be
Schlenk vessels. Compounds 1 and 1a were prepared by the
reaction of P S with 1-bromo- and 1-methoxynaphthalene
2
2
of a great interest since they are widely used as thionation
4
10
1
6
reagents and also as sources of new organophosphorus
respectively and recrystallised from dichloromethane or tolu-
ene respectively. Solvents and hmds were purified and/or dried
using standard methods. The IR spectra were recorded in
Nujol mull in cells equipped with KBr windows on a Bruker
IFS 28 spectrometer. Microanalyses were carried out by the
Department of Inorganic Chemistry, Palacky University, Czech
Republic.
2
compounds. The most well known examples of compounds
with such a structural motif are Lawesson’s reagent 2,4-bis-
(
p-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide
and Davy’s reagent methyl 2,4-bis(methylsulfanyl)-1,3,2,4-di-
thiadiphosphetane 2,4-disulfide, both of which are com-
mercially available. Synthetic routes using the silylating agents
3
4
methyl bis(trimethylsilyl)amine
or trimethylsilyl azide
towards organodithiadiphosphetane disulfides have been previ-
ously reported, which lead to new thiazadiphosphetidines. Here
we report results of the study of reactions of compounds 1 and
Preparations
؉
؊
[
MeC(NHSiMe ) ] [(C H )P(S) SP(S)(NHSiMe )] 2. A
3 2 10 6 2 3
suspension of compound 1 (0.50 g, 1.58 mmol) in MeCN
1
a with another silylating agent hexamethyldisilazane (hmds)
3
3
(
5 cm ) and hmds (1.67 cm , 7.90 mmol) was stirred at room
leading to new heterocyclic and cage compounds with electron-
withdrawing groups.
temperature until the reaction was finished (about 10 d),
during which time it became a yellow clear solution. The dark
yellow oil obtained by evaporation of solvent and residual hmds
in vacuo was then placed in an oil-bath and evacuated/heated
R
(
15 Pa/90 ЊC) for 10 min to remove tris(trimethylsilyl)amine.
The yellow solid obtained after cooling melted and decomposed
1
on heating above 90 ЊC (determined by H NMR spectroscopy).
S
The yield of this material is apparently quantitative but
purification of the crude product is difficult because of its sensi-
tivity to moisture, extreme solubility and tendency to create
oversaturated solutions in common solvents (acetonitrile,
dichloromethane, benzene, toluene). Even long standing (sev-
eral months) of the oily product at Ϫ20 ЊC did not lead to
precipitation of solid. Thermal instability makes it difficult to
P
P
S
S
S
1
1
R = H
a R = OMe
5
6
Crystal structure analysis of compounds 1 and 1a reveals
a cis configuration of the substituents, imposed by the
naphthalene-1,8-diyl, joining both phosphorus atoms and cre-
ating (together with the P S ring) a cage structure. This back-
bone makes it impossible to split molecules 1 and 1a into two
31
1
13
distil off N(SiMe ) . The purity was assessed by P, H and
C
3
3
2
2
NMR spectroscopy, which revealed that the product contains
about 4% (molar) of compound 3 and about 13% (molar) of
fragments each having one P atom as is common in reactions of
other organodithiadiphosphetane disulfides.
31
1
N(SiMe ) . NMR (in CD CN): P-{ H}, δ 66.1 (d, P ), 57.1
3
2
3
3
A
2
3
31
(
d, P ), J(PP) = 13.6, J(P H) = 20.5 Hz (from P spectrum);
B A
3 3
1
H, anion, δ 8.77 [1 H, ddd, J(PH) = 20.5, J(HH) = 7.3,
4
3
J(HH) = 1.4, H2], 8.72 [1 H, ddd, J(PH) = 20.5, H8], 7.98
Experimental
(
1 H, m, H6), 7.91 (1 H, m, H4), 7.59 (1 H, m, H7), 7.52 (1 H,
All manipulations were performed under dried nitrogen gas in
2
m, H3), 6.90 [1 H, d, J(PH) = 8.7 Hz, H11] and 0.39 (9 H, s,
H12); cation, δ 8.26 (2 H, s, H11x), 2.13 (3 H, s, H1x) and 0.33
1
3
1
1
(
18 H, s, H12x); C-{ H}, anion, δ 141.2 [1 C, d, J(PC) = 80.3,
1 3
†
‡
E-Mail: kilian@chemi.muni.cz
E-Mail: J.D.Woollins@lboro.ac.uk
C1], 136.0 [1 C, d, J(PC) = 101.0, J(PC) = 3.8, C9], 133.7 (2 C,
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180
1175

View Article Online
2
13
1
m, C5 and C6), 132.9 [1 C, d, J(PC) = 13.0, C8], 132.4 (1 C, s,
H7) and 0.05 [9 H, s, Si(CH ) ]; C-{ H}, δ 134.1 (s, C4 and
3 3
1 3
2
2
C4), 129.2 [1 C, d, J(PC) = 13.8, C2], 127.6 [1 C, t, J(PC) = 8.4
Hz, C10], 125.1 [1 C, d, J(PC) = 17.6, C7], 125.0 [1 C, d,
J(PC) = 16.8 Hz, C3] and 1.9 (3 C, s, C12); cation, δ 174.9 (1 C,
s, C2x), 20.6 (1 C, s, C1x) and Ϫ0.1 (6 C, s, C12x); N, δ 133.1
s, N11x and N11xЈ) and 68.5 (s, N11). IR (ν˜ max/cm ): 3184s,
125s and 3055s [ν(N᎐H)], 1683w and 1659w [ν(N᎐C ᎐N)],
C6), 133.3 [d, J(PC) = 103.0, C1 and C9], 133.4 [t, J(PC) =
11.5, C5], 131.8 (m, C2 and C8), 128.8 [t, J(PC) = 9.7 Hz, C10],
125.6 (m, C3 and C7) and 0.8 [s, Si(CH ) ]. IR (ν
3
2
3
Ϫ1
˜
/cm ): 648s
3
3
max
15
[ν(P᎐S)].
᎐
Ϫ1
(
ϩ
3
6
(
MeOC H )P(S)SN(SiMe )P(S) 3a. A suspension of com-
10 5 3
3
70s, 660s [ν(P᎐S)].
᎐
pound 2 (0.40 g, 1.15 mmol) in MeCN (5 cm ) and hmds (0.36
3
cm , 1.72 mmol) was heated at reflux for 3 h. The resulting light
yellow solution was concentrated in vacuo to 2 cm and placed
in a closed vessel in a Dewar flask with hot water and allowed to
3
R1
R2
cool slowly (10 d) to ambient temperature. Colorless crystals
of 3a were filtered off, washed with MeCN (2 × 0.5 cm ) and
4
6
5
3
3
7
11x
12x
NH Si(CH3)3
dried in vacuo. Yield 51 mg (11%), m.p. 169–171 ЊC (Found: C,
2
8
1x
CH3
2x
C
1
S
0
S 1
9
41.96; H, 4.02; N, 3.21; S, 24.39. C H NOP S Si requires C,
14 17
2 3
S
NH Si(CH3)3
PA
–S
PB
41.88; H, 4.27; N, 3.49; S, 23.96%). NMR (in CD Cl , for num-
2 2
31 1
NH11
11x′
12x′
bering of atoms see Fig. 2): P-{ H} (δ values calculated for
Si(CH3)3
1
2
1
AB system), δ 47.05 (d), 47.25 (d), J(PP) = 17.68 Hz; H, δ 8.58
1 H, m, H6), 8.34 (1 H, m, H8), 8.23 (1 H, m, H2), 7.65 (1 H,
m, H7), 6.99 (1 H, m, H3), 4.07 (3 H, s, H11) and 0.03 [9 H, s,
2
(
R1
R2
H
1
3
1
2
2
H
Si(CH ) ]; C-{ H}, δ 160.5 (s, C4), 133.9 [d, J(PC) = 12.2,
3 3
1 2
2
2
a
b
OMe
H
H
C8], 133.0 [d, J(PC) = 103.2, C9], 132.2 [d, J(PC) = 10.71, C2],
2
OMe
1
30.1 [t, J(PC) = 11.1, C10],3 128.4 (s, C6), 125.9 [t,
3
J(PC) = 12.2, C5], 124.9 [m, 3 J(PC) = 13.8, C7], 124.2 [d,
1
J(PC) = 109.4, C1], 103.8 [m, J(PC) = 14.5 Hz, C3], 56.4 (s,
؉
؊
[
MeC(NHSiMe ) ] [(MeOC H )P(S) SP(S)(NHSiMe )]
Ϫ1
3
2
10
5
2
3
C11) and 0.6 [s, Si(CH ) ]. IR (ν
˜
/cm ): 640s [ν(P᎐S)].
3
3
max
᎐
2
a and 2b. A mixture of isomers (molar ratio 1.3:1) was pre-
pared in the same fashion as for compound 2 from 1a (0.50 g,
.44 mmol) and hmds (1.52 cm , 7.2 mmol) in MeCN (5 cm ).
The resulting light yellow solid melts and decomposes on
heating above 90 ЊC or when exposed to moisture. Effectively
a quantitative yield was obtained; purity was assessed by
Ϫ1
Raman (ν
˜
/cm ): 639w [ν(P᎐S)].
max
3
3
1
؉
؊
[
NH (SiMe ) ] [(C H )P(S) SP(S)(NHSiMe )] ؒ0.5CH Cl
2
3
2
10
6
2
3
2
2
4
. A suspension of compound 1 (0.25 g, 0.79 mmol) in CH Cl
2 2
3 3
(
10 cm ) and hmds (0.83 cm , 3.95 mmol) was stirred at room
temperature; after 3 h it had become a clear yellow solution.
Stirring was continued for several hours, the reaction mixture
31
1
1
13
1
P-{ H}, H and C-{ H} NMR spectroscopy. Such mixtures
of isomers contain less than 3% (molar) of 3a and about 3%
3
was then concentrated to 7 cm and allowed to cool slowly to
31
1
(
(
molar) of N(SiMe ) . NMR (in CD Cl ): 2a, P-{ H}, δ 65.5
3 3 2 2
2 1 13
Ϫ20 ЊC. The clear yellow crystals of 4 were filtered off and
washed with n-hexane before being dried in vacuo. Compound 4
decomposes when exposed to moisture (determined by IR spec-
troscopy), m.p. 133–134 ЊC. Yield 0.246 g (51.1%) (Found: C,
d, P ), 58.0 (d, P ), J(PP) = 13.6 Hz; H and C spectra of
A
B
1
cation identical to that of 2; anion, H δ 8.89 [1 H, m,
3
3
J(HH) = 7.5, H8], 8.83 [1 H, m, J(HH) = 8.0, H2], 8.56 (1 H,
m, H6), 7.69 (1 H, m, H7), 6.95 (1 H, d, H3), 6.92 [1 H, d,
3
8.01; H, 6.18; N, 4.36; S, 20.94. C H N P S Si ؒ0.5CH Cl
19 36 2 2 4 3 2 2
2
2
J(PH) = 9.5 Hz, H11], 3.99 (3 H, s, OCH ) and 0.51 (9 H, s,
3
requires C, 38.43; H, 6.12; N, 4.60; S, 21.04%). NMR (in [ H ]-
acetone): P-{ H}, H and C-{ H} spectra of anion identical
to those of 2 (see Discussion); H, cation, δ 0.02 [18 H, s,
Si(CH ) ]; C-{ H}, cation, δ 1.22 [s, Si(CH ) ]. IR (ν
1
3
1
1
6
H12); C-{ H}, δ 158.0 (s, C4), 136.5 [dd, J(PC) = 101,
J(PC) = 3.8, C9], 133.7 [d, J(PC) = 12.6, C8], 133.2 [d,
31
1
1
13
1
3
1
2
2
1
2
J(PC) = 86, C1], 131.0 [d, J(PC) = 15.2, C2], 129.3 [t,
13
1
Ϫ1
˜
/cm ):
3
3
3
3
3
max
J(PC) = 10, C10], 127.4 (s, C6), 126.2 [t, J(PC) = 11.5, C5],
3
122s, 3056s [ν(N᎐H)], 655m, 640m [ν(P᎐S)].
3
3
᎐
1
5
24.6 [d, J(PC) = 16.4, C7], 103.1 [d, J(PC) = 17.0 Hz, C3],
3
3
1
1
6.68 (s, OCH ) and 2.6 [d, J(PC) <2 Hz, C12]; 2b, P-{ H}
3
2
1
13
Crystallography
δ 66.4 (d, P ), 56.7 (d, P ), J(PP) = 13.6 Hz; H and C spectra
A
B
1
of cation identical to that of 2; H anion, δ 8.93 [1 H, m,
J(HH) = 7.5, H2], 8.81 [1 H, m, J(HH) = 8.0, H8], 8.48 (1 H,
m, H4), 7.61 (1 H, m, H3), 7.01 (1H, d, H7), 6.78 [1 H, d,
Details of the data collections and refinements are summarised
in Table 1. Data were collected using graphite-monochrom-
atized Mo-Kα (λ = 0.710 73 Å) radiation on a KUMA KM-4
four circle κ-axis diffractometer equipped either with a modi-
fied Nonius low-temperature device (3a, 4) or with an Oxford
Cryostream Cooler (3). The cell parameters were determined
by least-squares refinement on diffractometer coordinates of
n centered reflections in the range (2θmin, 2θmax). Data were
collected in the 2θ range 4–50Њ with ω–2θ scan techniques.
Three standard reflections tested during measurement showed
no significant variation in intensity. Intensities were corrected
3
3
2
J(PH) = 8.8 Hz, H11], 3.97 (3 H, s, OCH ) and 0.51 (9 H, s,
3
1
3
1
1
H12); C-{ H}, δ 159.0 (s, C6), 141.3 [d, J(PC) = 81, Cl], 135.1
2
2
[
d, J(PC) = 14.1, C8], 129.9 [d, J(PC) = 13.8, C2], 129.4 [t,
1 3
3
J(PC) = 10, C10], 127.8 [dd, J(PC) = 107, J(PC) = 4.5, C9],
2
1
25.9 (s, C4), 125.8 [t, J(PC) = 11.4, C5], 124.4 [d,
J(PC) = 15.8, C3], 104.0 [d, J(PC) = 17.0, C7], 56.74 (s, OCH )
3
3
3
3
and 2.6 [d, J(PC) <2 Hz, C12].
7
(
C H )P(S)SN(SiMe )P(S) 3. A suspension of compound 1
0.50 g, 1.58 mmol) in MeCN (10 cm ) and hmds (0.50 cm , 2.37
for Lorentz-polarisation and absorption effects (DIFABS).8
10
6
3
3
3
(
All structures were solved by direct methods (SHELXS 86).
mmol) was heated under reflux for 8 h. The resulting clear yel-
low solution was concentrated in vacuo to 4 cm and placed in a
closed vessel inside a Dewar flask with hot water and allowed to
All non-hydrogen atoms were refined anisotropically by full-
3
2
matrix least-squares procedures based on F
(program
8
Ϫ1
2
2
SHELXL 93) with weight w = σ(F ) ϩ (aP) ϩ bP, where
o
2
2
c
cool slowly (10 d) to ambient temperature. Clear yellow crystals
P = (Fo ϩ 2F )/3. All hydrogen atoms were located from
3
of 3 were filtered off, washed with n-hexane (2 × 3 cm ) and
the Fourier-difference synthesis and refined isotropically. The
maximum ∆/σ after the last cycle of refinement was in all
cases less than 0.001.
dried in vacuo. Yield 218 mg (37.1%), m.p. 167–169 ЊC (Found:
C, 42.19; H, 4.13; N, 3.50; S, 25.31. C H NP S Si requires C,
13
15
2 3
4
2.03; H, 4.07; N, 3.77; S, 25.89%). NMR (in CDCl , for num-
CCDC reference number 186/897.
See http://www.rsc.org/suppdata/dt/1998/1175/ for crystallo-
graphic files in .cif format.
3
31
1
1
bering of atoms see Fig. 1): P-{ H}, δ 46.3 (s); H, δ 8.34 (2 H,
m, H2 and H8), 8.15 (2 H, m, H4 and H6), 7.69 (2 H, m, H3 and
1
176
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180

View Article Online
mental section), and also the data for the N,NЈ-bis(trimethyl-
silyl)acetamidinium cation. Three-bond correlation of C1x
with H11x and one-bond correlation of C1x with its hydrogens
were observed as well as interaction of the least shielded carbon
C2x with H11x and C1x. The proposed structure of the cation
hmds
1
S
S
S
S
P
P
NH
1
15
12,13
11
was supported also by H᎐ N GHMBC
and GSQMBC
SiMe3
SiMe3
experiments, showing one-bond correlation of hydrogen H11x
1
with N11x [ J(HN) = Ϫ76 Hz] as well as three-bond correlation
–
Me3SiSH
MeCN)
2 hmds
(MeCN)
3
of H11x with N11xЈ [ J(HN) = ϩ4.3 Hz] and thus confirming
(
the presence of two chemically equivalent NH groups bonded
2
hmds
14
3
to one C atom. The correlations of N11x with H1x [ J(HN) =
(CH2Cl2)
N(SiMe3)3
MeCN
+ 2
3
3
Ϫ4.8 Hz] and H12x [ J(HN) = Ϫ3.5 Hz] were observed as well
as one-bond interaction of nitrogen N11 with its hydrogen H11
N(SiMe3)3
+ 4
1
[
J(HN) = Ϫ71 Hz] and three-bond interaction of N11 with
3
Scheme 1
hydrogens H12 [ J(HN) = Ϫ3.5 Hz]. The infrared spectrum
of 2 contains characteristic bands at 1659 and 1683 cm
[ν(N᎐C ᎐N)] due to the amidinium cation as well as several
bands at 3055–3184 cm [ν(N᎐H)], confirming the presence of
Ϫ1
ϩ
NMR spectroscopy
Ϫ1
The NMR spectra were recorded on a Bruker Avance DRX-500
spectrometer. The values of small coupling constants summar-
ised in the Experimental section were read directly from corre-
sponding one-dimensional spectra (non-optimized). For
and C NMR spectroscopy SiMe was used as an internal
standard, for P NMR 85% H PO was used as an external
standard. Homo- and hetero-nuclear chemical shift correlation
spectra [double quantum filtered (DQF)-COSY, GHMBC,
GSQMBC ] were recorded using a 5 mm triple resonance
inverse probehead ( H-{ C}, {BB}, z-grad) equipped with a
z-gradient coil.
For gradient-enhanced heteronuclear multiple bond correl-
ation (GHMBC) experiments the following parameters were
more than one N᎐H group.
The analogous reaction of hmds with the methoxy derivative
1
a was also studied. Thus 1a with hmds in acetonitrile in molar
ratio 1:5 leads to a mixture of isomers 2a and 2b (molar ratio
.3:1), differing from each other only by the position of the
1
H
13
4
1
31
3
4
methoxy group on the naphthalene ring. A coproduct
N(SiMe ) and side product 3a were identified by NMR spec-
9
10
3 3
troscopy. Extreme solubility prevents purification of the crude
product by recrystallisation; no attempts were made to separate
isomers.
11
1
13
The molecular structures of compounds 2a and 2b were
unambiguously demonstrated by both one- and two-
dimensional NMR spectroscopy. A set of one-dimensional
1
1
used: sequence 90Њ( H)–∆-90Њ(X)-t /2-G1-180Њ( H)-G2-t /
1
1
31
13
1
13
1
31
31
1
1
NMR experiments ( H, H-{ P}, C-{ H}, C-{ H, P}, P-
{
1
13
2
3
-90Њ(X)-G3-acq(t ), for H᎐ C gradient ratios G1:G2:G3 =
1
1
31
13
31
2
H} allowed us to establish values of H᎐ P and C᎐ P
Ϫ1
1
15
0:18:24 G cm , ∆ = 60–80 ms, for H᎐ N gradient ratios
coupling constants summarised in the Experimental section.
The proposed structure and correct assignment of all signals
Ϫ1
G1:G2:G3 = 42:18:30 G cm , ∆ = 80–120 ms. For gradient-
enhanced single-quantum multiple bond correlation (GSQ-
31
in these spectra were confirmed also by GE-DQF-COSY{ P},
1
1
MBC) experiments: sequence 90Њ( H)–∆/2–180Њ( H)/180Њ(X)-
1
31
11
1
13
31
H᎐ P GSQMBC and H᎐ C GHMBC{ P} two-dimen-
1
1
1
∆
9
/2-90Њ( H)/90Њ(X)-t /2-180Њ( H)-t /2-G1-180Њ(X)-G2-90Њ( H)/
1
1
sional experiments, where similar correlation peaks as for 2
were found. An unequivocal confirmation of the position of the
methoxy group on the naphthalene ring was provided by DQF-
0Њ(X)-acq(t )/G3, evolution delays as for GHMBC spectra,
2
1 13 Ϫ1
gradient ratios for H᎐ C G1:G2:G3 = 12:36:±6 G cm ,
1
15
Ϫ1
1
31
for H᎐ N G1:G2:G3 = 4.8:52.8:±4.8 G cm , for H᎐ P
G1:G2:G3 = 12:41.6:±12 G cm , ∆ = 50–100 ms.
1
31
COSY and H᎐ P GSQMBC experiments. The first allowed us
to assign naphthalene ring hydrogen atoms, the second showed
correlations of hydrogen atoms H2 and H3 (two spin system)
in compound 2a with the phosphorus atom other than that
having correlation with hydrogen H11 and hydrogens, H6, H7,
H8 (three-spin system). On the other hand, hydrogens H7 and
H8 in compound 2b correlated with the same phosphorus atom
as that correlated with hydrogen H11.
Ϫ1
Results and Discussion
The reaction of compound 1 with hmds in acetonitrile gives
products 2 and 3 depending on the molar ratio used and the
temperature (Scheme 1). The proposed transition product (in
square brackets) is unstable and undergoes subsequent reac-
tions giving the products shown. The cation in 2 is probably
formed from a reaction of hmds with the MeCN solvent. We
Treatment of compound 1 with hmds in a molar ratio of
1:1.5 in acetonitrile leads to a mixture of products, from which
the product of partial desulfuration 2,4-(naphthalene-1,8-diyl)-
ϩ
speculate that (Me Si) NH is formed which undergoes rapid
3-trimethylsilyl-1,3,2,4-thiazadiphosphetidine 2,4-disulfide 3
3
2
2
reaction with the solvent. The reaction of 1a with hmds gives
products 2a, 2b and 3a. When a great molar excess of hmds is
used (1:5 to 1:10) the major products of the reaction are 2
together with N(SiMe ) . Compound 3 was identified as a
side product (4 molar %), its amount significantly increasing
at higher reaction temperatures (18 molar % at reflux temper-
ature).
was obtained in moderate yield. Previously reported reactions
of dithiadiphosphetane disulfides with methyl bis(trimethylsil-
3
yl)amine (Scheme 2) resulted in the synthesis of an NH substi-
tuted ring, whereas here we obtained the NSiMe derivative.
3
3
3
This yellow solid is very soluble in CHCl and poorly soluble in
3
MeCN. Mechanistically the reaction leading to 3 and a side
product SiMe (SH) requires a reactant molar ratio of 1:1
3
The molecular structure of compound 2 was unambiguously
demonstrated by both one- and two-dimensional NMR spec-
troscopy. The naphthalene ring hydrogen atoms were assigned
(Scheme 1); when the reaction was performed with only a small
excess of hmds (molar ratio 1:1.1) unchanged 1 was observed
31
1
in the mixture even after 48 h reflux. The P-{ H} NMR spec-
trum of 3 (singlet, δ 46.3) confirms the equivalence of both
31
using a DQF-COSY experiment. The assignment of P signals
1
31
1
was based on the H᎐ P GHMBC experiment, where inter-
phosphorus atoms; H NMR reveals the aromatic protons as
action of P with H11 was found. Clear interactions of P with
well as confirming retention of one SiMe group.
B
B
3
aromatic hydrogens H6, H7, H8 and H4 as well as weak inter-
The crystal structure of compound 3 (Table 2, Fig. 1) con-
actions with H12 were observed. Atom P interacted with aro-
firms that 1 has undergone a ring-cleavage and subsequent ring-
A
matic hydrogens H2, H3 and H4 and H6, but not with any
closure reaction to give a P NS ring. The asymmetric unit in 3
consists of two formula units which are slightly different from
each other, as is shown in Table 2, where bond angles with
2
1
13
trimethylsilyl hydrogens. The H᎐ C GHMBC experiment
1
13
allowed us to assign all H and C NMR signals (see Experi-
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180
1177

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Table 1 Details of the data collections and refinements for compounds 3, 3a and 4
3
3a
4
Ϫ
ϩ
Empirical formula
M
C H NP S Si
C H NOP S Si
14 17
C H NP S Si C H NSi ؒ2CH Cl
13 16 2 4 6 20 2 2
1
3
15
2
3
2
3
371.5
401.5
609.4
Colour, habit
Crystal size/mm
T/K
Yellow, rhomboid
1.00 × 1.00 × 0.15
150.0(1)
Colourless, needle
0.80 × 0.30 × 0.30
293(2)
Yellow, rhomboid
0.8 × 0.7 × 0.4
133(2)
Crystal system
Space group
Triclinic
P1
Monoclinic
P2 /n
1
Monoclinic
P2 /c
1
¯
a/Å
b/Å
c/Å
α/Њ
8.944(2)
7.984(2)
20.430(3)
11.142(2)
17.698(9)
12.841(3)
14.008(4)
11.490(2)
17.165(4)
76.08(2)
β/Њ
γ/Њ
89.74(2)
87.54(2)
98.53(2)
104.08(4)
Centered reflections (n)
34
50
29
2
U/Å
θ Range of centered reflections/Њ
18.2–28.0
1710.5(6)
4
19.5–25.8
1797.3(6)
4
17.3–18.8
3088(2)
4
3
Z
Ϫ3
D /Mg m
1.442
1.484
1.311
c
Maximum, minimum transmission
µ/mm
0.90, 0.51
0.679
0.82, 0.59
0.656
0.78, 0.61
0.627
Ϫ1
F(000)
Index ranges
768
832
1284
Ϫ10 р h р 10,
Ϫ13 р k р 13,
Ϫ20 р l р 0
6226
Ϫ9 р h р 9,
Ϫ24 р k р 0,
0 р l р 13
3297
0 р h р 21,
Ϫ12 р k р 0,
Ϫ16 р l р 16
4736
Reflections measured
Independent reflections (Rint
Data/parameters
a, b
)
6008 (0.0721)
6008/481
0.0939, 2.4000
0.884
3139 (0.1000)
3139/266
0.1000, 3.1648
0.980
4591 (0.0238)
4591/435
0.0600, 7.0000
0.980
2
S on F
Final R1, wR2 [I > 2σ(I)]
0.0391, 0.1138
0.0492, 0.1242
0.538, Ϫ0.544
0.0476, 0.1322
0.0793, 0.1541
0.590, Ϫ0.611
0.0402, 0.1091
0.0484, 0.1143
0.349, Ϫ0.0554
(
all data)
Ϫ3
Largest difference peak, hole/e Å
Table 2 Selected bond lengths (Å) and angles (Њ) in compound 3
P(1)᎐S(3a)
P(2)᎐S(3a)
P(1)᎐N
P(1)᎐S(1)
P(1)᎐C(1)
Si᎐N
2.113(1)
2.123(1)
1.680(3)
1.908(1)
1.796(3)
1.782(2)
P(1)᎐S(3b)
P(2)᎐S(3b)
P(2)᎐N
P(2)᎐S(2)
P(2)᎐C(9)
2.125(1)
2.114(1)
1.683(2)
1.906(1)
1.797(3)
P(1)᎐S(3)᎐P(2)
N᎐P(1)᎐S(3)
N᎐P(2)᎐S(2a)
N᎐P(1)᎐S(1)
S(2)᎐P(2)᎐S(3a)
C(1)᎐P(1)᎐S(1)
C(1)᎐P(1)᎐S(3)
N᎐P(1)᎐C(1)
P(1)᎐N᎐Si(a)
P(2)᎐N᎐Si(a)
73.55(4)
89.14(9)
121.20(9)
119.01(9)
119.60(5)
117.7(1)
101.5(1)
102.8(1)
126.6(1)
133.2(2)
P(1)᎐N᎐P(2)
N᎐P(2)᎐S(3)
N᎐P(2)᎐S(2b)
S(1)᎐P(1)᎐S(3)
97.90(1)
89.08(9)
120.08(9)
121.65(5)
S(2)᎐P(2)᎐S(3b) 120.18(5)
C(9)᎐P(2)᎐S(2)
C(9)᎐P(2)᎐S(3)
N᎐P(2)᎐C(9)
P(1)᎐N᎐Si(b)
P(2)᎐N᎐Si(b)
118.2(1)
101.6(1)
102.2(1)
130.6(1)
129.3(1)
R
S
S
N
S
R
R
P
S
S
S
S
P
6 or 7
P
P
R
R′
Fig. 1 Structure of the independent molecule in compound 3
8
a, b, c R′ = Me
5
5
5
a R = Me
(when treated with 6)
b R = Et
the P NS rings are planar. In the cis derivative 3 the ring NP S is
2 2
c R = C6H4OMe-p
9a, b R′ = SiMe3
not planar with a dihedral angle of 146Њ about the P ؒ ؒ ؒ P axis.
The transannular P ؒ ؒ ؒ P and S ؒ ؒ ؒ N distances are 2.54 and
2.69 Å respectively. The internal P᎐S᎐P angle is noticeably
(
when treated with 7)
Scheme 2 Reagents: NMe(SiMe ) 6, SiMe N 7
3
2
3
3
5
reduced [73.55(4)Њ] relative to that in 1 [80.0(1)Њ] and to those
∆
> 3σ are listed for both independent molecules (a and b). The
in known NP S rings, both cis and trans derivatives (78–
2
3,15,16
SiMe group in formula unit a is slightly twisted about the
80Њ).
Similarly the internal P᎐N᎐P angle in 3 [97.90(1)Њ] is
3
N ؒ ؒ ؒ Si axis when compared to unit b. The naphthalene part of
the molecule, phosphorus and sulfur atoms S(1) and S(2) lie
very close to a mean plane [maximum deviation 0.12 Å for
S(1)]. There are few reports of the X-ray characterisation of
significantly reduced vs. that in other known NP S ring deriv-
2
atives (104–106Њ). Similar trends could be seen in derivatives
containing the P N ring. In cis-PhP(S)(NEt) P(S)Ph, where the
2
2
2
dihedral angle about the P ؒ ؒ ؒ P axis is 168.5Њ, the P᎐N᎐P angle
(95.0Њ) is slightly reduced vs. that in the trans derivative (96.7Њ),
3,15,16
P NS rings;
2
only one derivative has the cis configuration
17
(
cis-2-cyclohexylamino-3-cyclohexyl-4-methylsulfanyl-1,3,2,4-
where the P N ring is planar. On the other hand the internal
2 2
15
thiazadiphosphetidine 2,4-disulfide ), however in all of them
P᎐S and P᎐N bond lengths in 3 are comparable to those in
1
178
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180

View Article Online
Table 3 Selected bond lengths (Å) and angles (Њ) in compound 3a
Table 4 Selected bond lengths (Å) and angles (Њ) in compound 4
P(1)᎐S(3)
P(1)᎐N
P(1)᎐S(1)
P(1)᎐C(1)
Si᎐N
2.127(2)
1.691(3)
1.909(1)
1.783(4)
1.792(4)
P(2)᎐S(3)
P(2)᎐N
P(2)᎐S(2)
P(2)᎐C(9)
2.116(2)
1.689(3)
1.905(2)
1.804(4)
P(1)᎐S(1)
P(1)᎐S(3)
P(2)᎐S(2)
P(1)᎐C(1)
Si(1)᎐N(1)
Si(3)᎐N(2)
2.111(1)
1.970(1)
1.942(1)
1.812(3)
1.748(3)
1.804(3)
P(2)᎐S(1)
P(1)᎐S(4)
P(2)᎐N(1)
P(2)᎐C(9)
Si(2)᎐N(2)
2.082(1)
1.978(1)
1.626(3)
1.817(3)
1.850(3)
P(1)᎐S(3)᎐P(2)
N᎐P(1)᎐S(3)
N᎐P(1)᎐S(1)
S(1)᎐P(1)᎐S(3)
C(1)᎐P(1)᎐S(1)
C(1)᎐P(1)᎐S(3)
N᎐P(1)᎐C(1)
P(1)᎐N᎐Si
73.49(5)
88.1(1)
P(1)᎐N᎐P(2)
N᎐P(2)᎐S(3)
N᎐P(2)᎐S(2)
S(2)᎐P(2)᎐S(3)
C(9)᎐P(2)᎐S(2)
C(9)᎐P(2)᎐S(3)
N᎐P(2)᎐C(9)
P(2)᎐N᎐Si
97.4(2)
88.5(1)
P(1)᎐S(1)᎐P(2)
S(3)᎐P(1)᎐S(4)
S(3)᎐P(1)᎐S(1)
S(2)᎐P(2)᎐S(1)
C(1)᎐P(1)᎐S(1)
C(1)᎐P(1)᎐S(3)
C(9)᎐P(2)᎐S(2)
Si(2)᎐N(2)᎐Si(3)
100.44(6)
116.98(6)
103.07(6)
106.80(6)
102.8(1)
111.9(1)
113.8(1)
127.1(2)
P(2)᎐N(1)᎐Si(1)
N(1)᎐P(2)᎐S(2)
S(4)᎐P(1)᎐S(1)
N(1)᎐P(2)᎐S(1)
C(9)᎐P(2)᎐S(1)
C(1)᎐P(1)᎐S(4)
C(9)᎐P(2)᎐N(1)
132.1(2)
113.1(2)
112.66(6)
110.2(1)
105.7(1)
108.5(1)
107.1(2)
122.2(1)
120.42(7)
115.2(1)
102.7(1)
103.6(2)
131.2(2)
120.5(1)
120.82(7)
116.1(1)
102.6(1)
103.6(2)
127.0(2)
Fig. 3 Molecular structure of compound 4
Fig. 2 Molecular structure of compound 3a
angles C(1)᎐P(1)᎐S(1) and C(9)᎐P(2)᎐S(2), however the differ-
ence from those in 3 is less than 2Њ. As in 3 the molecules pack
with the naphthalene rings face to face.
other known NP S ring derivatives. In 3 the molecules pack
2
with the naphthalene rings face to face in a typical π–π overlap
with an interplanar separation of 3.49 Å. The closest non-
bonded intermolecular S ؒ ؒ ؒ S distance 3.56 Å is between S(1)
and S(2).
In an attempt to exclude formation of the N,NЈ-bis(trimethyl-
silyl)acetamidinium cation we performed the reaction of com-
pound 1 with hmds in dichloromethane (Scheme 1). The reac-
tion in 1:5 molar ratio is completed in a much shorter time than
that where acetonitrile is used, probably because of the much
higher solubility of 1 in dichloromethane. From a complex mix-
ture of products compound 4 crystallizes on cooling in good
yield and purity. It is soluble in acetonitrile, but its solution is
unstable and turns into 2 (conversion is completed after several
days), also in dichloromethane and chloroform. However in the
latter solvents it undergoes decomposition to an equilibrium
mixture of 4 and two unidentified products (present also in the
reaction mixture before as well as after precipitation of 4), each
containing two chemically inequivalent phosphorus atoms. The
A methoxy-derived relative 3a was obtained in a similar
fashion to 3. This white air-stable compound is soluble in
dichloromethane and acetonitrile. The reaction was completed
in a shorter time because of the higher solubility of 1a vs. 1. The
chemical shifts of both phosphorus atoms in 3a (δ 47.05, 47.25)
are similar to that of 3 (δ 46.3) and suggest that the two com-
31
1
pounds have similar structures. The P-{ H} NMR spectrum
AB system) is as expected, where the methoxy group has an
(
electronic effect through the aromatic naphthalene system.
Substitution of one of the internal S atoms by an N atom
2
31
1
1
13
1
resulted in a substantial increase in the magnitude of the J(PP)
P-{ H}, H and C-{ H} NMR spectra of the anion are, as
expected, very similar to those of 2, slight differences in chem-
18
coupling constant to 17.7 Hz (6.5 Hz for 1, 7.4 Hz for 1a).
1
13
1
The H and C-{ H} NMR signals were assigned by analogy
of 3a with 2a and 2b.
ical shifts occurring because of the presence of a different
2
cation and solvent ([ H ]acetone). We were unable to identify
6
ϩ
1
The crystal structure of compound 3a (Table 3, Fig. 2)
reveals a very similar geometry to that of 3, as was expected on
peaks belonging to NH2 hydrogens in the H NMR spectrum
of 4, probably due to fast chemical exchange.
6
the basis of comparison between 1 and 1a, where the methoxy
The crystal structure of 4 (Table 4, Fig. 3) reveals that 1 has
undergone a ring-cleavage reaction to give a product with an
ionic structure. Its anionic part is identical to that in 2, the
structure of which was solved by NMR techniques. The struc-
ture of the cation is noteworthy; to our knowledge no report
of the X-ray characterisation of the hexamethyldisilazan-2-
ium ion has been previously published. The C H P part of
group does not exert any steric effect on the P NS ring system.
2
The naphthalene part of the molecule, phosphorus, sulfur
atoms S(1) and S(2) and methoxy O and C(11) lie very close to a
mean plane [maximum deviation 0.09 Å for C(11) and P(2)].
The ring NP S is non-planar with a dihedral angle of 142.6Њ
2
about the P ؒ ؒ ؒ P axis (about 3Њ more hinged than that in 3). All
corresponding bond lengths and almost all bond angles are not
substantially different from those in 3. The only exceptions are
10
6
2
molecule is noticeably distorted from planar; atoms P(1) and
P(2) lie 0.25 and 0.21 Å above and below the mean plane
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180
1179

View Article Online
respectively. The C P S ring is hinged with the C P and P S
5 A. M. Z. Slawin, D. J. Williams, P. T. Wood and J. D. Woollins,
3
2
3
2
2
J. Chem. Soc., Chem. Commun., 1987, 1741.
M. R. St. J. Foreman, J. Novosad, A. M. Z. Slawin and J. D.
Woollins, J. Chem. Soc., Dalton Trans., 1997, 1347.
planes inclined by 51.2Њ with respect to each other. The opening
of the P2S2 ring results in substantial lengthening of the
P ؒ ؒ ؒ P distance vs. that in 1 (3.22 vs. 2.73 Å) and widening of
P(1)᎐S(1)᎐P(2) angle [100.44(6) vs. 80.0(1)Њ]. However, this angle
is comparable to that in related molecules (C H )P(S)(SMe)-
6
7
N. G. Walker and D. Stuart, Acta Crystallogr., Sect. B, 1983, 39,
1
58.
1
0
6
8 G. M. Sheldrick, SHELXS 86, SHELXL 93, University of
Göttingen, 1993.
9 A. L. Davis, E. D. Laue, J. Keeler, D. Moskau and J. Lohman,
J. Magn. Reson., 1991, 94, 637.
1
9
SP(S)(OMe) [103.0(1)Њ] and (C H )P(S)(OCH CH OH)SP-
S)(OCH CH OH) [101.8(1)Њ]. The P(1)᎐S(3) [1.9689(14) Å]
10
6
2
2
20
(
2 2
and P(1)᎐S(4) [1.9785(13) Å] distances indicate delocalisation
1
1
0 A. Bax and M. F. Summers, J. Am. Chem. Soc., 1986, 108, 2093.
1 R. Marek, L. Králík and V. Sklenáø, Tetrahedron Lett., 1997, 38,
of the negative charge in the PS group. Hydrogen bonds link
2
the S(4) atom to an NH (anion) hydrogen (2.60 Å) and to one
6
65.
of the NH (cation) hydrogens (2.54 Å).
12 R. Marek, J. Dostál, J. Slavík and V. Sklenáø, Molecules, 1996, 1, 166.
3 G. E. Martin, R. C. Crouch, M. H. M. Sharaf and P. L. Schiff, jun.,
J. Nat. Prod., 1996, 59, 2.
4 R. Marek, V. Sklenáø, J. Dostál and J. Slavík, Tetrahedron Lett.,
2
1
1
1
Acknowledgements
J. M. wishes to express his gratitude to the Ministry of
Education of the Czech Republic for grant VS 96 095 and to
the Grant Agency of the Czech Republic for grant No. 203/95/
1
996, 37, 1655.
5 C. Donath, B. Wallis, M. Meisel and P. Leibnitz, Z. Anorg. Allg.
Chem., 1989, 576, 33.
16 M. R. St. J. Foreman, A. M. Z. Slawin and J. D. Woollins, Chem.
Commun., 1997, 1269.
1
190. J. T. is grateful to the Grant Agency of the Czech
1
1
1
2
7 G. J. Bullen and P. A. Tucker, Acta Crystallogr., Sect. B, 1973, 29,
Republic for grant No. 203/97/0955.
2
878.
8 G. Grossmann, H. Beckmann, P. Rademacher, K. Kruger and
G. Ohms, J. Chem. Soc., Dalton Trans., 1995, 2797.
9 M.-E. Eleftheriou, J. Novosad, D. J. Williams and J. D. Woollins,
J. Chem. Soc., Chem. Commun., 1991, 116.
0 P. Kilián, J. Touؒín, J. Marek, J. D. Woollins and J. Novosad, Main
Group Chem., 1996, 1, 425.
References
1
M. P. Cava and M. I. Levinson, Tetrahedron, 1985, 41, 5061;
H. Davy, J. Chem. Soc., Chem. Commun., 1982, 457.
2
R. Shabana and S. S. Atrees, Phosphorus Sulfur Silicon Relat.
Elem., 1995, 105, 57; S. Scheibye, R. Shabana and S.-O. Lawesson,
Tetrahedron, 1982, 38, 993.
3
4
W. Zeis and H. Henjes, Z. Naturforsch., Teil B, 1979, 34, 1334.
H. W. Roesky and M. Dietl, Angew. Chem., Int. Ed. Engl., 1973, 12,
4
25.
Received 19th November 1997; Paper 7/08348C
1
180
J. Chem. Soc., Dalton Trans., 1998, Pages 1175–1180