2334
D.M. Griffith et al. / Inorganica Chimica Acta 363 (2010) 2333–2337
Table 1
analyses were determined on a Bruker Smart Apex CCD diffracto-
meter. Elemental analysis was performed by the RCSI Analytical
Service, Department of Pharmaceutical and Medicinal Chemistry,
Royal College of Surgeons in Ireland, 123 St. Stephen’s Green, Dub-
lin 2, Ireland.
Crystallographic data collection and experimental conditions for Bit/BitO and cis-
Pd(en)(BitÀ1H)2ÁH2O.
Compound
Bit/BitO
cis-[Pden(BitÀ1H)2]ÁH2O
C16H18N4O3S2Pd
100(2) K
Empirical formula
Temperature
Crystal system
Space group
a (Å)
C14H10N2O3S2
293(2) K
monoclinic
P21/n (#14)
14.1571(12)
6.9559(6)
15.1323(13)
90
111.288(1)
90
4
full-matrix
least-squares on F2
1.042
21 905
3023 [Rint = 0.0213]
triclinic
ꢀ
P1 (#2)
2.3. Synthesis of Benzisothiazolinone (Bit)
5.5189(4)
10.0133(8)
16.7384(13)
72.199(2)
85.255(2)
85.7870(10)
2
full-matrix
least-squares on F2
1.058
b (Å)
c (Å)
Hydroxylamine hydrochloride (4.16 g, 60 mmol) was added to
an aqueous sodium hydroxide (4.80 g, 120 mmol) solution
(25 cm3) and then added dropwise to a methanolic solution
(50 cm3) of methylthiosalicylate (5 g, 30 mmol). The solution was
stirred at room temperature for 72 h, after which time the solution
was acidified to pH 4.5 using 5% HCl solution. A white solid precip-
itated, which was filtered and dried. The white solid was recrystal-
lised from hot water:methanol (2:1) to give white crystals of Bit.
Yield: 1.5 g, 33%. Anal. Calc. for C7H5NOS: C, 55.61; H, 3.33; N,
a
(°)
b (°)
c
(°)
Z
Refinement method
Goodness-of-fit (GOF) on F2
Reflections collected
Independent reflections
10 711
4901 [Rint = 0.0235]
9.26; S, 21.21. Found: C, 55.22; H, 3.30; N, 9.03; S, 21.20%. mmax
/
cmÀ1 3039s, 3058s (N–H), 1655vs, 1636vs (C@O); dH (400 MHz,
d6 DMSO): 11.89 (1H, br s, NH), 7.98 (1H, d, 3J 8.0 Hz, aromatic
H), 7.88 (1H, d, 3J 7.8 Hz, aromatic H), 7.61 (1H, t, 3J 7.5 Hz, aro-
matic), 7.41 (1H, t, 3J 7.5 Hz, aromatic H); ESI-MS m/z: 152
([MÀH]+).
2.6. X-ray data collection and structure determination for Bit/BitO and
cis-Pd(en)(BitÀ1H)2ÁH2O
Crystal data and experimental details for Bit/BitO and cis-
Pd(en)(BitÀ1H)2ÁH2O are summarised in Table 1. Additional data
are available in the Supplementary material. X-ray data were col-
lected with a Bruker Smart Apex CCD diffractometer at 293 and
Good-quality crystals of a benzisothiazolinone:benzisothiazoli-
none-1-oxide, Bit/BitO, co-crystal were obtained from the filtrate
after 1 month standing at room temperature.
100 K, respectively using monochromated Mo
Ka radiation,
(k = 0.71073 Å) and the /– scan method. The structures were
x
solved by direct method (SHELXS-97) [29] and refined by full-matrix
least-squares using SHELXL 97-2 package [29].
2.4. Synthesis of cis-Pd(en)(BitÀ1H)2ÁH2O
Pd(en)Cl2 (0.19 g, 0.80 mmol) and AgNO3 (0.27 g, 1.56 mmol) in
deionised water (15 cm3) were stirred overnight in the dark. The
insoluble AgCl was filtered and Bit (0.25 g, 1.68 mmol) dissolved
in an aqueous solution (5 cm3) of NaOH (0.067 g, 1.68 mmol) was
added to the filtrate. A cream/yellow solid precipitated instantly.
The reaction was stirred at room temperature for 1 h, filtered,
washed with cold H2O and dried over P2O5. Yield: 0.26 g, 68%. Anal.
Calc. for C16H18N4O3PdS2: C, 39.63; H, 3.74; N, 11.55; S, 13.23.
3. Results and discussion
3.1. Synthesis and spectroscopic characterisation of Bit
Bit was unexpectedly synthesised by reacting methyl thiosali-
cylate with hydroxylamine hydrochloride in the presence of NaOH
(Scheme 1). Synthesis of Bit has been previously reported and via a
number of routes; the transamination of sulfonamides [30], the
cyclisation of acyl azides [31] and significantly the cyclisation of
thiobenzohydroxamic acids [32]. Therefore it is proposed that
reaction of methyl thiosalicylate with a twofold excess of hydrox-
ylamine and fourfold excess of base initially gave 2-merca-
ptobenzohydroxamic acid, which subsequently cyclised in the
presence of NaOH to give Bit (Scheme 1).
Found: C, 39.25; H, 3.55; N, 11.32; S, 13.05%. m
max/cmÀ1 3224s,
3196s (N–H, NH2), 1656vs, (C@O); dH (400 MHz, d6 DMSO): 7.69
(2H, d, 3J 7.7 Hz, aromatic H), 7.62 (2H, d, 3J 8.0 Hz, aromatic H),
7.39 (2H, dt, 3J 7.8 and 4J 1.2 Hz, aromatic H), 7.22 (2H, dt, 3J 7.0
and 4J 0.8 Hz, aromatic H), 5.47 (4H, br, s, NH2), 2.59 (4H, br, s,
CH2); ESI-MS m/z: 466 ([MÀH]+).
Good-quality crystals of cis-Pd(en)(BitÀ1H)2ÁH2O were obtained
from a cooled, saturated aqueous methanol solution.
Bit was obtained in low yield but excellent purity and was char-
acterised by elemental analysis, IR and 1H NMR spectroscopy and
mass spectrometry. The IR spectrum of Bit contains bands at
1655 and 1637 cmÀ1 which may be assigned as the symmetric
2.5. Synthesis of cis-Pt(NH3)2(BitÀ1H)2.DMF
and asymmetric stretches corresponding to m
(C@O). The 1H NMR
Cis-Pt(NH3)I2 (0.54 g, 1.12 mmol) and AgNO3 (0.37 g,
2.19 mmol) in deionised water (15 cm3) were stirred overnight in
the dark. The insoluble AgI was filtered and Bit (0.37 g, 2.46 mmol)
dissolved in an aqueous solution (5 cm3) of NaOH (0.098 g,
2.46 mmol) was added to the filtrate. A yellow solid precipitated
instantly. The reaction was stirred at room temperature for 1 h, fil-
tered, washed with cold H2O and dried over P2O5. The yellow solid
was subsequently recrystallised from a cooled, saturated DMF
solution. Yield: 0.34 g, 50%. Anal. Calc. for C17H23N5O3PtS2: C,
33.77; H, 3.83; N, 11.58; S, 10.61. Found: C, 33.38; H, 3.50; N,
spectrum of Bit in d6 DMSO shows an N–H resonance at
11.89 ppm and exhibits 4 resonances at 7.98, 7.88, 7.61 and
7.41 ppm corresponding to the four aromatic protons. ESI-MS in
the positive mode assisted in identifying Bit with a mass peak at
152 amu.
Good-quality crystals of co-crystallised Bit/BitO were obtained
from the mother liquor after 1 month standing suggesting that
Bit is air oxidised over time to give the corresponding 1-oxide,
BitO.
11.26; S, 10.36%.
m
max/cmÀ1 3200s, 3097s (N–H, NH3), 1663vs
(C@O); dH (400 MHz, d6 DMSO): 7.69 (2H, d, 3J 7.8 Hz, aromatic
H), 7.61 (2H, d, 3J 8.3 Hz, aromatic H), 7.39 (2H, t, 3J 7.5 Hz, aro-
matic H), 7.22 (2H, t, 3J 7.3 Hz, aromatic H), 4.67 (6H, br, s, NH3);
ESI-MS m/z: 530 ([MÀH]+).
3.2. X-ray structural characterisation of Bit/BitO
The structure of co-crystallised Bit/BitO is shown in Fig. 1; se-
lected bond lengths and angles are given in the Supplementary