Novel triorganotin(IV) complexes of β-diketonates bearing two heterocycles in their structures

Article abstract of DOI:10.1016/j.ica.2010.12.002

Novel triorganotin(IV) derivatives of β-diketonate Q ligands (HQ in general, in detail HQ^fur = 1-phenyl-3-methyl-4-(2-furancarbonyl)- pyrazol-5-one, HQ^thi = 1-phenyl-3-methyl-4-(2-thienylcarbonyl)- pyrazol-5-one) of general formula (

Full text of DOI:10.1016/j.ica.2010.12.002

Inorganica Chimica Acta 367 (2011) 98–107
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Inorganica Chimica Acta
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Novel triorganotin(IV) complexes of b-diketonates bearing two heterocycles
in their structures
a
a
a
Claudio Pettinari a, Fabio Marchetti b, , Ivan Timokhin , Alessandro Marinelli , Corrado Di Nicola ,
⇑
Brian W. Skelton c, Allan H. White c
a School of Pharmacy, Università degli Studi di Camerino, via S Agostino 1, 62032 Camerino MC, Italy
b School of Science and Technology, Università degli Studi di Camerino, via S Agostino 1, 62032 Camerino MC, Italy
c Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA 6009, Australia
a r t i c l e i n f o
a b s t r a c t
Novel triorganotin(IV) derivatives of b-diketonate Q ligands (HQ in general, in detail HQfur = 1-phenyl-3-
methyl-4-(2-furancarbonyl)-pyrazol-5-one, HQthi = 1-phenyl-3-methyl-4-(2-thienylcarbonyl)-pyrazol-5-
one) of general formula (Q)SnR3ꢀxH2O (R = Ph, x = 0; R = Bun or Me, x = 1) have been synthesized and
spectroscopically and thermally characterized. Triphenyltin(IV) complexes have been isolated as anhy-
drous compounds while trialkyltin(IV) are always monohydrated. The structures of (Qfur)SnPh3 and
(Qthi)SnMe3(OH2) are recorded. The tin atoms are five-coordinate in both. In the first, the pyrazolonate
ligand behaves as an O,O0-bidentate; there are two similar but independent molecules in the structure.
In the quasi-trigonal-bipyramidal environments, Sn–O(acyl) are 2.478(3), 2.364(3), Sn–O(pyrazolonate)
2.050(2), 2.079(2), Sn–C 2.123(4)–2.162(3) Å with the longer O(acyl) and a phenyl group quasi-trans
(O–Sn–C 162.5(1), 160.8(1)°). In (Qthi)SnMe3(OH2), the three methyl groups are equatorial (Sn–C
2.1259(9)–2.1380(8) Å); Sn–O(Qthi,OH2) are 2.2143(5), 2.3350(6) Å, O–Sn–O 175.36(2)°. Trimethyltin(IV)
derivatives decompose on heating with release of H2O and SnMe4 and formation of (Q)2SnMe2. Decom-
position occurs also within two days after dissolution of (Q)SnMe3(OH2) in chloroform.
Article history:
Received 21 July 2010
Received in revised form 10 November 2010
Accepted 1 December 2010
Available online 7 December 2010
Keywords:
Triorganotin(IV)
Acylpyrazolonate
NMR
Crystal structures
TGA-DTA
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
Among organometallic compounds, those of tin(IV) play a spe-
cial role, due to their wide application in industry as wood preser-
vatives, stabilizers for PVC, marine antifouling agents, and in
agriculture as fungicides and biocides [1]. In addition, many
organotin(IV) compounds have been tested for their in vitro activ-
ity against a large variety of tumor lines and have been found to be
as effective or better than traditional heavy metal anticancer drugs
such as cis-platin [2].
O
S
Me
Me
O
O
N
N
OH
OH
N
N
The rapid rise in the industrial, agricultural and biological appli-
cations of organotin(IV) compounds during the last few decades
has led to their accumulation in the environment and in biological
systems [3]. In particular, the trialkyltin(IV) [R3Sn(IV)]+ and triaryl-
tin(IV) [Ar3Sn(IV)]+ derivatives exert powerful toxic actions on the
central nervous system. Within series of [R3Sn(IV)]+ compounds,
the lower homologues (R = methyl, Me; ethyl, Et) are the most
toxic when administrated orally; the toxicity diminishes progres-
sively from tri-n-propyl to tri-n-octyl, the latter tending not to be
toxic at all [4].
HQthi
HQfur
Chart 1.
Our long interest in organotin(IV) chemistry has been particu-
larly concerned with their coordination and structural chemistry
with chelating N- and O-donor ligands such as tris(pyrazol-
yl)borates [5], bis- and tris-(pyrazolyl)alkanes [6] and 4-acyl-5-
pyrazolonates [7]. The latter are well known b-diketonate-type
donors, widely used as extractants and sequestering agents toward
heavy metals [8]. Previous reports on tin(IV) acylpyrazolonates
have shown interesting structural features [9] and some of them
⇑
Corresponding author. Tel.: +39 0737 402217; fax: +39 0737 637345.
E-mail address: fabio.marchetti@unicam.it (F. Marchetti).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.12.002

C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
99
have also displayed interesting anti-proliferative effects on some
2.2.2. Metal complexes
human melanoma cell lines, particularly toward SK-MEL-5, which
is intrinsically resistant to all conventional treatment modalities
[10].
Here we extend our studies on different acylpyrazolones con-
taining a heterocycle with an additional donor atom in the acyl
pendant, in particular 2-substituted furan and thiophene rings
(Chart 1), and on their interaction toward triorganotin(IV) accep-
tors, where the organic group is methyl, n-butyl or phenyl. These
proligands are potentially polydentate donors and could be useful
in the design and construction of inorganic polynuclear materials.
2.2.2.1. (Qfur)SnPh3 (1). A benzene solution (30 cm3) of (Ph3Sn)2O
(1.0 mmol) was added to a benzene solution (30 cm3) of the ligand
HQfur (2.0 mmol), and the reaction mixture was refluxed for about
2 h. After removing the solvent under reduced pressure on a rotary
evaporator, a thick oil was obtained. This was treated with diethyl
ether and petroleum ether, and a solid formed, which was re-crys-
tallized from a benzene/petroleum ether mixture. It is soluble in
chloroform, benzene, methanol, acetone, acetonitrile and dmso.
Yield 64%. M.p. 119–122 °C. Elemental analyses: Anal. Calc. for
C
33H26N2O3Sn: C, 64.21; H, 4.25; N, 4.54. Found: C, 64.48; H,
4.32; N, 4.68%. Km (CH2Cl2, conc. 10ꢁ3 M): 0.7 S cm2 molꢁ1. IR (nu-
jol) data: 3129w (C–Harom), 1603vs (C@O), 1592s, 1555s, 1523s
(C@N + C@C), 273s, 257vs, 236s (Sn–C), 454s, 444vs, 369s
(Sn–O), 689s, 658m, 629s, 607m, 592m, 509m, 391w, 291m. 1H
m
m
m
2. Experimental
m
m
2.1. General comments
(CDCl3) NMR (293K): d, 2.22s, 2.44s (3H, C3–CH3), 6.53br, 6.61br,
7.40m, 7.64m, 7.76m (23H, Sn–C6H5, C(@O)C4H3O and N–C6H5).
13C (CDCl3) NMR (293 K): d, 17.5s (C3–CH3), 127.5–129.5vbr,
135.7s (2J(Sn–C): 58.4 Hz) 137.1s (2J(Sn–C): 61.3 Hz), 145.9s, 146.4s
(Carom of Sn–Ph), 118.7s, 119.5s, 121.2br, 122.7br, 126.2br,
126.6s, 127.5–129.5vbr, 129.7s, 148.3s, 149.1s, 151.3s (Caromatic of
Qfur), 112.7s, 112.9 (C4), 137.9s, 138.1s (C3), 163.9s, 165.2 (C5),
175.0s (CO). 119Sn (CDCl3) NMR (293 K): d, ꢁ176, ꢁ180br. TGA-
DTA (mg% vs. °C): heating from 30 to 500 °C with a speed of
5 °C/min; at 122.0 °C onset of fusion (
at 178.6 °C another endothermal event (
180 to 500 °C progressive decomposition, with a final residue of
41% weight. Derivatives 2–4 were synthesised in a similar way.
The tin(IV) and organotin(IV) halides were purchased from Alfa
(Karlsruhe) and Aldrich (Milwaukee) and used as received. The
proligands HQfur and HQthi were prepared according to the litera-
ture [7]. The reactions were carried out under an N2 stream using
Schlenk techniques. Solvents were dried by standard techniques
and distilled prior to use.
The samples for microanalyses were dried in vacuo to constant
weight (20 °C, ca. 0.1 Torr). Elemental analyses (C, H, N) were per-
formed in-house with a Fisons Instruments 1108 CHNS-O Elemen-
tal Analyzer. IR spectra were recorded from 4000 to 100 cmꢁ1 with
a Perkin–Elmer System 2000 FT-IR instrument. 1H and 119Sn NMR
spectra were recorded on a Mercury Plus Varian 400 spectrometer
operating at room temperature (400 MHz for 1H and 149.3 MHz for
119Sn). The 119Sn NMR experiments were carried out aliasing by
varying the centre of the window, to avoid falling-out resonances,
with a spectral width of 900 ppm. Melting points were taken on an
IA 8100 Electrothermal Instrument. The electrical conductivity
measurements (KM, reported as S cm2 molꢁ1) of the dichlorometh-
ane solutions were measured with a Crison CDTM 522 conductim-
eter at room temperature. TGA-DTA spectra were obtained with a
STA 6000 Simultaneous Thermal Analyzer Perkin–Elmer by con-
ducting the thermal studies under an inert atmosphere of dry
nitrogen.
D
Hfusion = 7.0 kJ/mol), then
D
H = 23.7 kJ/mol), from
2.2.2.2. (Qthi)SnPh3 (2). Yield 67%. M.p. 130–132 °C. Elemental anal-
yses: Anal. Calc. for C33H26N2O2SSn: C, 62.58; H, 4.14; N, 4.42; S,
5.06. Found: C, 62.31; H, 4.23; N, 4.53; S, 4.83%. Km (CH2Cl2, conc.
10ꢁ3 M): 0.6 S cm2 molꢁ1. IR (nujol) data: 3097w, 3066w
m
(C–Har-
(C@N + C@C),
(Sn–C), 447vs, 427s, 347s, 327m (Sn–O),
om), 1600s
259s, 247s, 233m
m(C@O), 1593sh, 1569vs, 1558s, 1515s m
m
m
692s, 670m, 649s, 624m, 571m, 538m, 510m, 485m, 405w,
393w, 294w, 276s. 1H (CDCl3) NMR (293 K): d, 2.06br, 2.23s (3H,
C3–CH3), 7.05br, 7.10t, 7.30–7.50m, 7.60m 7.70t, 7.87br (23H,
Sn–C6H5, C(@O)C4H3S and N–C6H5). 13C (CDCl3) NMR (293 K): d,
16.9s, 17.1s (C3–CH3), 128.0–130.0vbr, 135.7s (2J(Sn–C): 59.1 Hz)
137.0s (2J(Sn–C)
: 64.7 Hz), 148.2s, (Carom of Sn–Ph), 120.5br,
121.1br, 122.8s, 126.3s, 127.3s, 127.9s, 128.0–130.0vbr, 138.0s,
148.7s (Caromatic of Qthi), 104.2s, 105.5 (C4), 135.4s, 136.8s (C3),
163.3s, 164.7 (C5), 182.1s, 183.3s (CO). 119Sn (CDCl3) NMR
(293 K): d, +188, ꢁ131. TGA-DTA (mg% vs. °C): heating from 30
to 500 °C with a speed of 5 °C/min; from 140 to 500 °C progressive
decomposition, with a final residue of 42% weight.
2.2. Syntheses
2.2.1. Ligands
The proligands HQfur and HQthi were synthesized using the pro-
cedure reported by Jensen [11].
2.2.1.1. 1-Phenyl-3-methyl-4-(2-furancarbonyl)-pyrazol-5-one (HQfur).
Yield 71%. M.p. 103–105 °C. Elemental analyses: Anal. Calc. for
2.2.2.3. (Qfur)SnBun3ꢀH2O (3). Yield 64%. M.p. 120–123 °C. Elemental
analyses: Anal. Calc. for C27H40N2O4Sn: C, 56.37; H, 7.01; N, 4.87.
Found: C, 56.17; H, 7.14; N, 4.91%. Km (CH2Cl2, conc. 10ꢁ3 M):
C
15H12N2O3: C, 67.16; H, 4.51; N, 10.44. Found: C, 66.91; H, 4.67;
N, 10.40%. IR (nujol) data: 3350br (C–Harom),
(N–HꢀꢀꢀO), 3095w
2700br (C@O), 1580s, 1528s (C@N + C@C),
m
m
0.9 S cm2 molꢁ1. IR (nujol) data: 3156vbr
m
(H2O), 3091w
(C@N + C@C), 608vs,
m(Sn–O), 692s, 677s, 660s,
m(C–Har-
m
(O–HꢀꢀꢀO), 1630vs
m
m
om), 1587s
m(C@O), 1564s, 1528vs, 1514s m
689s, 651m, 604m, 585m, 510m, 391m, 291w. 1H (CDCl3) NMR:
d 2.63s, (3H, C3–CH3), 6.66q, 7.32t, 7.72t (3H, C(@O)C4H3O),
7.38t, 7.43t, 7.29d (5H, N-C6H5), 11.5br, (1 H, OHꢀꢀꢀO).
532 m (Sn–C), 441s, 386s, 349s
m
647m, 593m, 499m, 392w, 290m, 251m. 1H (CDCl3) NMR
(293 K): d, 0.82t, 0.90t, 1.13m, 1.24m, 1.40–1.70m br (27H, Sn–
C4H9), 2.04s, 2.33s (3H, C3–CH3), 2.65br (2H, H2O), 6.56dbr,
7.21br, 7.26t, 7.42t, 7.63br, 7.78d (8H, C(@O)C4H3O and N–C6H5).
2.2.1.2.
1-Phenyl-3-methyl-4-(2-thienylcarbonyl)-pyrazol-5-one
(HQthi). Yield 65%. M.p. 152–155 °C. Elemental analyses: Anal. Calc.
13C (CDCl3) NMR (293 K): d, 19.1s, 27.0s, 27.3s, 27.8s (1J(Sn–C)
:
2
3
for C15H12N2O2S: C, 63.36; H, 4.25; N, 9.85; S, 11.28. Found: C,
356 Hz; J(Sn–C): 19 Hz, J(Sn–C): 74 Hz) (Sn–CH2CH2CH2CH3), 13.8s
(C3–CH3), 117.6s, 122.7s, 126.3s, 128.8s, 145.5s, 150.4s (Caromatic
of Qfur), 111.9s (C4), 138.9s (C3), 163.2s (C5), 172.4s (CO). 119Sn
(CDCl3) NMR (293 K): d, +140, ꢁ175. TGA-DTA (mg% vs. °C): heat-
ing from 30 to 500 °C with a speed of 5 °C/min; from 80 to 100 °C
loss of one water molecule (weight loss found 3.08%, calcd. 3.12%,
63.49; H, 4.29; N, 9.57; S, 11.04%. IR (nujol) data: 3400br
m
(N–HꢀꢀꢀO),
2600br
1515m
m
(O–HꢀꢀꢀO), 3089w
m(C–Harom), 1626vs m(C@O) 1601s,
m(C@N + C@C), 688m, 670m, 635m, 608w, 595m, 563w,
514w, 490m, 432w, 408m, 383s, 369s, 314m, 296w, 277s. 1H (CDCl3)
NMR: d 2.45s, (3H, C3-CH3), 7.17t, 7.27t, 7.74d (3H, C(@O)C4H3S),
7.47t, 7.72t, 7.85d (5H, N–C6H5), 10.5br, (1 H, OHꢀꢀꢀO).
D
H = 12.3 kJ/mol), from 140 to 500 °C progressive decomposition,

100
C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
with a final residue of 24% weight corresponding to SnO (calcd.
23.41%).
7.68d, 7.77d (8H, C(@O)C4H3S and N–C6H5). 13C (CDCl3) NMR
(293 K): d, ꢁ0.8s (1J(Sn–C): 365 Hz) (Sn–CH3), 16.0s (C3–CH3),
122.5s, 126.4s, 127.4s, 128.9s, 131.9s, 132.5s, 149.0s, 150.3s (Caro-
2.2.2.4. (Qthi)SnBu3nꢀH2O (4). Yield 73%. M.p. 121–122 °C. Elemental
analyses: Anal. Calc. for C27H40N2O3SSn: C, 54.84; H, 6.82; N, 4.74;
S, 5.42. Found: C, 54.96; H, 6.95; N, 4.85; S, 5.22%. Km (CH2Cl2,
of Qthi), 103.7s (C4), 138.5s (C3), 163.1s (C5), 182.8s (CO).
matic
119Sn (CDCl3) NMR (293 K): d, +173, ꢁ175. TGA-DTA (mg% vs.
°C): heating from 30 to 500 °C with a speed of 5 °C/min; from 80
conc. 10ꢁ3 M): 0.7 S cm2 molꢁ1. IR (nujol) data: 3257vbr
m
(H2O),
(C@O), 1536vs, 1510s
(Sn–C), 444m, 439m, 369m,
to 140 °C loss (
half of SnMe4 (total weight loss found 24.0%, calcd. 23.1%), at
142.9 °C onset of fusion ( Hfusion = 12.3 kJ/mol), from 160 to
DH = 92.5 kJ/mol) of one water molecule and one-
3094w
m(C–Harom), 1661 m d(H2O), 1571s
m
m(C@N + C@C), 617m, 604s, 519m
m
D
344s
m
(Sn–O), 691s, 676m, 652m, 640m, 562m, 496m, 408w,
500 °C progressive decomposition, with a final residue of 32%
weight corresponding to SnS (calcd. 32.41%).
392w, 290m, 252m. 1H (CDCl3) NMR (293 K): d, 0.81t, 1.02t,
1.18m, 1.42m, 1.80m br (27H, Sn–C4H9), 2.10br (2H, H2O), 2.18br,
2.31br (3H, C3–CH3), 7.11t, 7.25t, 7.39t, 7.59d, 7.73t (8H,
C(@O)C4H3S and N–C6H5). 13C (CDCl3) NMR (293 K): d, 18.5s,
2.2.2.7. (Qfur)2SnMe2 (7). To a methanol solution (30 ml) of QSH
(2 mmol) were added KOH (2 mmol) and (CH3)2SnCl2 (1 mmol). A
precipitate formed immediately. The mixture was stirred overnight
and the precipitate was then filtered off, washed with methanol
(10 ml) and dried under reduced pressure at room temperature.
This was recrystallised from chloroform/methanol and shown to
be compound 7. Yield 86%. M.p. 170–174 °C. Elemental analyses:
Anal. Calc. for C32H28N4O6Sn: C, 56.25; H, 4.13; N, 8.20. Found: C,
56.14; H, 4.20; N, 8.03%. Km (CH2Cl2, conc. 10ꢁ3 M):
26.9s, 27.3s, 27.7s (1J(Sn–C): 342 Hz; J(Sn–C): 18 Hz, J(Sn–C): 72 Hz)
(Sn–CH2CH2CH2CH3), 13.8s (C3–CH3), 122.9s, 126.5s, 127.5s,
128.3s, 132.1s, 132.7s, 149.2s, 150.1s (Caromatic of Qthi), 103.5s
(C4), 138.2s (C3), 163.0s (C5), 182.2s (CO). 119Sn (CDCl3) NMR
(293 K): d, +154, ꢁ176. TGA-DTA (mg% vs. °C): heating from 30
to 500 °C with a speed of 5 °C/min; from 80 to 100 °C loss of one
water molecule (weight loss found 2.98%, calcd. 3.04%,
2
3
D
H = 63.8 kJ/mol), from 140 to 500 °C progressive decomposition,
0.5 S cm2 molꢁ1
.
IR (nujol) data: 3050w
(C@O), 1574s, 1542s, 1524s (C@N + C@C), 593m, 583s,
(Sn–C), 476s, 437m, 396m, 374s (Sn–O), 684s, 661s,
m(C–Harom), 1601m,
with a final residue of 25% weight corresponding to SnS (calcd.
25.49%).
1591s
532m
m
m
m
m
646m, 625vs, 615m, 508s, 405w, 335w, 296m, 280m, 254w.
246w. 1H (CDCl3) NMR (293 K): d, 0.96s (2J(Sn–H): 98.8 Hz) (6H,
Sn–CH3), 2.31s (6H, C3–CH3), 6.62d, 7.25m, 7.67d, 7.93d (16H,
C(@O)C4H3O and N–C6H5). 13C (CDCl3) NMR (293 K): d, 9.6s (1J(Sn–
C): 928 Hz) (Sn–CH3), 17.2s (C3–CH3), 118.8s, 121.5s, 125.9s,
129.1s, 146.1s, 148.8s, 151.8s (Caromatic of Qfur), 112.6s (C4),
138.4s (C3), 163.4s (C5), 176.1s (CO). 119Sn (CDCl3) NMR (293 K):
d, ꢁ323. TGA-DTA (mg% vs. °C): heating from 30 to 500 °C with a
2.2.2.5. (Qfur)SnMe3ꢀH2O (5). A benzene solution (30 cm3) of the li-
gand HQfur (1.0 mmol) was added to
a methanolic solution
(10 cm3) of sodium methoxide (1.0 mmol) and refluxed for 1 h. A
benzene solution (20 cm3) of Me3SnCl (1.0 mmol) was then added
to the above solution dropwise and the reaction mixture was stir-
red at room temperature for about 3 h. Sodium chloride was fil-
tered off and the solvent removed under reduced pressure on a
rotary evaporator until a thick oil was obtained. This was treated
with diethyl ether and light petroleum, and a brown solid afforded.
It was re-crystallized from benzene/petroleum ether mixture and
shown to be compound 5. Yield 66%. M.p. 130–132 °C. Elemental
analyses: Anal. Calc. for C18H22N2O4Sn: C, 48.14; H, 4.94; N, 6.24.
Found: C, 47.87; H, 4.90; N, 6.09%. Km (CH2Cl2, conc. 10ꢁ3 M):
speed of 5 °C/min; at 141.3–160.8 °C onset of fusion
(DHfu-
sion = 8.9 kJ/mol), from 170 to 500 °C progressive decomposition,
with a final residue of 31% weight corresponding to SnO (calcd.
30.00%). Derivative 8 was synthesised in a similar way.
2.2.2.8. (Qthi)2SnMe2 (8). Yield 81%. M.p. 165–166 °C. Elemental
analyses: Anal. Calc. for C32H28N4O4S2Sn: C, 53.72; H, 3.94; N,
7.83; S, 8.96. Found: C, 53.46; H, 4.05; N, 7.82; S, 8.64%. Km
(CH2Cl2, conc. 10ꢁ3 M): 0.6 S cm2 molꢁ1. IR (nujol) data: 3097w
1.1 S cm2 molꢁ1. IR (nujol) data: 3105vbr
1521vs, 1501s (C@N + C@C), 558vs, 545s, 534sh
389m, 340s (Sn–O), 689s, 661s, 649m, 621m, 608m, 590m,
m
(H2O), 1577s
m(C@O),
m
m(Sn–C), 430m,
m
502m, 401w, 305m, 299m, 251m. 1H (CDCl3) NMR (293 K): d,
0.49s (2J(Sn–H): 56.4 Hz) (9H, Sn–CH3), 1.25s (2H, H2O), 2.36s (3H,
C3–CH3), 6.57br, 6.61br, 7.19br, 7.27t, 7.41t, 7.62br, 7.67br,
7.79d, 7.93d (8H, C(@O)C4H3O and N–C6H5). 13C (CDCl3) NMR
(293 K): d, ꢁ0.5s (1J(Sn–C): 387 Hz) (Sn–CH3), 14.7s (C3–CH3),
117.2s, 122.6s, 126.5s, 128.7s, 132.3s, 145.8s, 150.5s (Caromatic of
Qfur), 110.9s (C4), 138.6s (C3), 163.3s (C5), 172.6s (CO). 119Sn
(CDCl3) NMR (293 K): d, +149br. TGA-DTA (mg% vs. °C): heating
from 30 to 500 °C with a speed of 5 °C/min; from 80 to 140 °C
m
(C–Harom), 1593s
m
(C@O), 1548vs, 1520s
m
(C@N + C@C), 589m,
572s, 542m (Sn–C), 456m, 428s br, 375m, 356s
m
m(Sn–O), 694s,
646s, 640sh, 622s, 509m, 491w, 404w, 301w, 289w, 274w, 251w,
247w. 1H (CDCl3) NMR (293K): d, 0.97s (2J(Sn–H): 98.0 Hz) (6H,
Sn–CH3), 2.15s (6H, C3–CH3), 7.13t, 7.25m, 7.54d, 7.65d, 7.96d
(16H, C(@O)C4H3S and N–C6H5). 13C (CDCl3) NMR (293 K): d, 9.6s
(1J(Sn–C): 901 Hz) (Sn–CH3), 16.9s (C3–CH3), 121.4s, 125.9s, 127.5s,
129.2s, 132.3s, 133.0s, 148.6s (Caromatic of Qthi), 104.9s (C4),
138.4s (C3), 162.7s (C5), 182.6s (CO). 119Sn (CDCl3) NMR (293 K):
d, ꢁ315. TGA-DTA (mg% vs. °C): heating from 30 to 500 °C with a
(D
H = 11.23 kJ/mol) loss of one water molecule and one-half of
SnMe4 (total weight loss found 25.0%, calcd. 23.9%), at 141.3–
160.8 °C onset of fusion ( Hfusion = 8.98 kJ/mol), from 170 to
speed of 5 °C/min; at 142.9 °C onset of fusion (DHfusion = 12.3 kJ/
mol), from 160 to 500 °C progressive decomposition, with a final
D
500 °C progressive decomposition, with a final residue of 31%
weight corresponding to SnO (calcd. 30.00%). Derivative 6 was syn-
thesised in a similar way.
residue of 32% weight corresponding to SnS (calcd. 32.41%).
2.3. Structure determinations
2.2.2.6. (Qthi)SnMe3ꢀH2O (6). Yield 80%. M.p. 134–136 °C. Elemental
analyses: Anal. Calc. for C18H22N2O3SSn: C, 46.48; H, 4.77; N, 6.02;
S, 6.89. Found: C, 46.28; H, 4.86; N, 5.92; S, 6.65%. Km (CH2Cl2,
Full sphere of ‘low’-temperature CCD/area detector diffractom-
eter data were measured (monochromatic Mo
Ka radiation
(k = 0.71073 Å), -scans) yielding Ntotal reflections, these merging
x
conc. 10ꢁ3 M): 0.9 S cm2 molꢁ1. IR (nujol) data: 3105vbr
m
(H2O),
(C@N + C@C),
m(Sn–O), 689s,
to N unique (Rint cited) after absorption correction, these being
used in the full matrix least squares refinements on F2, refining
anisotropic displacement parameter forms for the non-hydrogen
atoms, hydrogen atom treatment following a riding model. Reflec-
1681mbr d(H2O), 1561s
m
(C@O), 1538vs, 1508vs
m
553vs, 542s
m(Sn–C), 442sh, 430 m, 373 m, 348 m
675m, 650m, 616w, 602m, 519w, 497w, 402w, 306m, 251m. 1H
(CDCl3) NMR (293 K): d, 0.37s (2J(Sn–H): 53.2 Hz) (9H, Sn–CH3),
1.24s (2H, H2O), 2.30s (3H, C3–CH3), 7.12t, 7.25t, 7.40 m, 7.60d,
tion weights were (
reflections with I > 2(I) were considered ‘observed’. Results are
r
2(F2o) + (aP)2 (+ bP))ꢁ1 (P = (F2+ 2F2)/3). No
o c

C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
101
given below and in the tables and figures, the latter showing non-
X
X
hydrogen atom ellipsoids at the 50% probability amplitude level,
hydrogen atoms having arbitrary radii of 0.1 Å. Neutral atom com-
plex scattering factors were used within the SHELXL 97 program [12].
Me
Sn
O
O
O
O
Me
Me
2 HQ + 2 NaOMe + Me2SnCl2
N
N
Me
N
N
MeOH
- 2 NaCl
2.3.1. Crystal/refinement data
2.3.1.1. (Qfur)SnPh3 (1). C33H26N2O3Sn, M = 617.3. Triclinic, space
1
ꢀ
group P1 ðCi ; No: 2Þ; a = 11.802(2), b = 13.937(3), c = 18.225(4) Å,
a
= 108.913(4), b = 101.353(5), c
= 97.104(5)°, V = 2723(1) Å3 (T
7, X = O
8, X = S
ca. 153 K). Dc (Z = 4) = 1.506 g cmꢁ3 Mo = 0.98 mmꢁ1; specimen:
. l
0.36 ꢂ 0.36 ꢂ 0.15 mm; ‘T’min/max = 0.90 (‘empirical’/multiscan cor-
rection). 2hmax = 70°; Nt = 45928, N = 22950 (Rint = 0.034),
No = 14725; R1 = 0.049, wR2 = 0.16 (a = 0.062, b = 4.9); S = 1.09.
Scheme 2.
3.2. Infrared Spectroscopy
2.3.1.2. (Qthi)SnMe3(OH2) (6). C18H22N2O3SSn, M = 465.1. Mono-
clinic, space group P21/c ðC52h; No: 14Þ, a = 11.7698(1), b =
10.2815(1), c = 16.2938(2) Å, b = 98.608(1)°, V = 1949.52(3) Å3 (T
In the solid state, the proligands HQ are likely to exist as a mix-
ture of both the amino-diketonic form, exhibiting a broad absorp-
ca. 100 K). Dc (Z = 4) = 1.585 g cmꢁ3
. l
Mo = 1.44 mmꢁ1; specimen:
2hmax = 112°; Nt =
No = 17174; R1 = 0.029,
tion due to an intermolecular
m
(N–HꢀꢀꢀO) mode in the range 3350–
3400 cmꢁ1, and of the keto-enol form with an intramolecular
m(O–
0.44 ꢂ 0.27 ꢂ 0.23 mm;
214648, N = 25798
wR2 = 0.074 (a = 0.038); S = 0.97.
Variata. Water molecule hydrogen atoms were located and
refined.
‘T’min/max = 0.87.
HꢀꢀꢀO) mode that affords a very broad band at 2600–2700 cmꢁ1
(Rint = 0.039),
[13]. Upon coordination these absorptions disappear and the
m
(C@O) at 1626–1630 cmꢁ1 undergoes a red shift in the range
1603–1561 cmꢁ1, in accordance with deprotonation of HQ and
involvement of both carbonyl groups in bonding with the metal,
particularly in the case of derivatives 1 and 2; in the monohydrate
derivatives 3–6 we find weak interactions with neighbouring
hydrogen atoms of a water molecule resulting in a broad band be-
tween 3100 and 3250 cmꢁ1, as previously observed for similar
3. Results and discussion
3.1. Synthesis of derivatives 1–8
compounds [9d]. Below the
have assigned the vibrations of the azomethine bond in the pyra-
zole and the (C@C) of Ph and heteroaromatic rings. By careful
comparison of the far-IR of the proligands and their tin derivatives,
m
(C@O) band down to 1500 cmꢁ1 we
Derivatives 1–4 have been synthesized by direct interaction be-
tween HQ (HQ = HQfur or HQthi) proligands and (R3Sn)2O (R = Ph or
Bun) in benzene at reflux. By contrast, trimethyltin(IV) derivatives
5 and 6 have been synthesized from interaction between the so-
dium salts of 4-acyl-5-pyrazolones and Me3SnCl in benzene at
room temperature. While triphenyltin(IV) derivatives 1 and 2 are
air and moisture stable, all of the others (3–6) absorb water when
exposed to atmosphere, and have been characterized as monohy-
drated compounds (Q)SnR3(OH2) (R = Me or Bun) (Scheme 1). They
are very soluble in all common organic solvents, such as chloro-
form, benzene, methanol, acetone, acetonitrile and dmso, but
insoluble in saturated hydrocarbons and water. Conductivity mea-
surements in acetonitrile and acetone have confirmed their non-
electrolyte nature.
The dimethyltin(IV) derivatives 7 and 8 have been synthesized
from dimethyltin(IV) dichloride in methanol and sodium methox-
ide by using a 1:2 metal to ligand ratio (Scheme 2). They are air and
moisture stable, highly soluble in chlorohydrocarbon solvents,
dmso and acetone, where they are non-electrolytes, and insoluble
in diethyl ether, alcohols, hydrocarbons and water.
m
we have also tentatively assigned as m(Sn–O) modes some new
strong bands in the range 400–500 cmꢁ1 [14].
In the far-IR spectra of triphenyltin(IV) derivatives 1 and 2 the
m
as(Sn–C) and ms(Sn–C) have been observed in the range 200–
300 cmꢁ1 [15], whereas for tributyl- and trimethyl-tin(IV) deriva-
tives 3–6 novel absorptions in the range 500–620 cmꢁ1 due to
mas(Sn–C) and
ms(Sn–C) modes have been assigned thus [16]. The
presence of s(Sn–C) in the far-IR of the monohydrate derivatives
m
3–6 seems to indicate (for a TBP trans-O–SnR3-O system) a devia-
tion from planarity of the SnR3 moiety, with a lowering of the local
symmetry from D3h to C3v. Moreover, the band at 3100–3200 cmꢁ1
in the IR spectra of 3–6 can be attributed to intermolecular H-
bonded water [9d,17].
In the IR spectra of 7 and 8 the broad band of the neutral HQ
proligands has disappeared upon coordination and the
band is shifted to lower frequencies. In the far-IR region new
absorptions due to Sn–C and Sn-O stretching modes have been
m(C@O)
X
HQ + NaOMe + Me3SnCl
X
R
Sn
R
R
Sn
O
benzene
- NaCl
O
O
+ H2O(vap)
Me
OH2
O
R
Me
-MeOH
N
N
R
N
R
N
benzene
- 1/2 H2O
HQ + 1/2 (R3Sn)2O
(R = Ph or Bun)
3, X = O, R = Bun
4, X = S, R = Bun
5, X = O, R = Me
6, X = S, R = Me
1, X = O, R = Ph
2, X = S, R = Ph
Scheme 1.

102
C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
Fig. 1. 1H NMR spectrum in CDCl3 of derivative 5 after two days from sample dissolution.
assigned, on the basis also of infrared studies on analogous com-
pounds previously reported [9]. The presence of more than one
into tetraorganotin(IV) and diorganotin(IV) derivatives. In fact
the resonance at 0.06 ppm is due to Sn(CH3)4 [19], while those at
0.96 and at 2.31 ppm can be attributed respectively to Sn–CH3
and C3–CH3 in the Qfur component of (Qfur)2Sn(CH3)2 [20].
m(Sn-C) mode seems indicative of some distortion from regular
octahedral geometry.
An analogous behaviour has been previously observed in the
case of (acac)SnMe3 (acac = 2,4-pentanedionate) [21] and (oxi-
n)SnMe3 (oxin = 8-hydroxyquinolinato) [22]. By contrast, triphen-
yltin(IV) derivatives 1 and 2 are stable in solution for several days.
13C NMR spectra are in good agreement with previous observa-
3.3. NMR Spectroscopy
The proligands HQ exist in chloroform in the keto-enol tauto-
meric form as confirmed by the broad resonance up to 10.0 ppm
in their 1H NMR spectra, originating in (O–HꢀꢀꢀO) systems as previ-
ously observed in examples of other 4-acylpyrazolones [9]. The
disappearance of such signals in the proton spectra of 1–6 indi-
cates coordination of the donors in anionic form. Moreover, a slight
shielding of C3–CH3 in Q ligands is generally observed, while aro-
matic protons present a more complex pattern upon chelation. In
the 1H NMR of the triphenyltin(IV) adducts 1–2 it has not been
possible to distinguish between signals due to aromatic protons
of the ligand and those linked to tin, but integration takes their
presence into account. By contrast, in the 1H NMR of tributyl-
and trimethyl tin(IV) derivatives 3–6 multiplets for butyl and sing-
lets for methyl groups bound to tin have been found between 0 and
2 ppm, with tin-proton coupling constants 2J(Sn–H) in the range 55–
58 Hz for 5 and 6, which is typical of tetracoordinate species [18].
We have observed that in solution derivatives 3–6 progressively
decompose to tetraorganotin(IV) and diorganotin(IV) acylpyrazol-
onates. As an example here we describe the decomposition process
of 5 as followed by the 1H NMR technique over two days after
dissolution of the sample in chloroform. Apart the set of proton
resonances due to the starting species (Qfur)SnMe3(OH2), two
new Sn–CH3 resonances appear in the 1H NMR spectrum at
0.06 ppm (2J(Sn–H): 53.0 Hz) and 0.96 ppm (2J(Sn–H): 100.4 Hz),
together with an additional peak at 2.31 ppm (Fig. 1). This may
be explained by a progressive decomposition of triorganotin(IV)
1
tions. In detail, the values of the J(Sn–C) coupling constants of tri-
methyltin(IV) derivatives
5
and
6
are 387 and 365 Hz,
respectively, and by applying the empirical relationship between
1J(Sn–C) and the angle h(C–Sn–C) proposed by Holecek and Lycka
(1J(Sn–C) = 9.99 h(C–Sn–C) ꢁ746 [23]), values of 113 and 111° are
calculated for h(C–Sn–C), in accordance with all methyl groups in
the equatorial plane of a trigonal bipyramidal environment on
tin, and in good agreement with the structural results of derivative
6 (see below).
We have also performed 119Sn NMR studies at room tempera-
ture for derivatives 1–6 which absorb between ꢁ180 and
+190 ppm. In particular, derivative 1 shows close resonances
around ꢁ180 ppm, in a range typical of a five-coordinate cis-
O2SnR3 TBP geometry [23], for which, in principle, the three iso-
mers (a–c) shown in Scheme 3 are possible. Clearly, however, the
isomer (c) is not feasible due to the steric limitations of the acy-
lpyrazolonate ligand, so that only the former two isomers are
likely, one with both carbonyl arms of Qfur in equatorial positions
and the other with one equatorial and one axial position occupied
by the two oxygen atoms of Qfur (Scheme 3).
By contrast, derivatives 2–4 and 6 display two well-separated
resonances, one at negative values (in the range from ꢁ122 to
ꢁ176 ppm) and the other at positive values (in the range from
+140 to +188 ppm). In the case of 2 the value at +188 ppm can

C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
103
C
Sn
C
O
Sn
C
O
C
O
O
O
C
C
C
C
Sn
C
O
(b)
(a)
(c)
Me
N
O
O
O
Ph
N
O
O
O
Me
N
Ph
Sn
Ph
Ph
Sn
Ph
Ph
N
CDCl3
Scheme 3.
Fig. 2. TGA spectrum of derivative 3.
be ascribed to the presence of a tetrahedral OSnPh3 species arising
from rupture of an Sn–O bond in the five-coordinate cis-O2SnR3
TBP geometry (Scheme 4). By contrast, for 3, 4 and 6 the positive
value arises from tetrahedral OSnR3 species after breaking of the
Sn–OH2 bond in solution (Scheme 4) [24], while the negative value
can be attributed to the aquo trialkyltin(IV) species having trans-
O2SnR3 TBP geometry. An additional possibility is that the apical
position of the water molecule is occupied by a sulfur or oxygen
donor atom of the heterocycle (thiophene of furan) of a neighbour-
ing complex molecule. However, 119Sn NMR studies carried out at
different molar concentrations of the sample didn’t afford any
detectable shift in these resonances, as expected for the case of
intermolecular interactions.
fur
(Q )SnMe3(H2O) (5), 25°C
first plateau, 100°C
second plateau, 170°C
Finally, derivative 5 shows a unique resonance at +149 ppm, in
accordance with fast and complete breaking of the Sn–OH2 bond
after dissolution of the sample in deuterochloroform and the pres-
ence of only the tetrahedral OSnMe3 species.
fur
(Q )2SnMe2 (7), 25°C
1H NMR spectra of 7 and 8 indicate a skewed trans-octahedral
geometry about the tin atom, that has been inferred from the
2J(Sn–H), which are 98.8 and 98.0 Hz for 7 and 8, respectively. By
applying the Lockhart relationship between the C–Sn–C angle
and tin-proton 2J coupling constant [19a], angles of 160.1° and
158.6° have been calculated for 7 and 8, respectively.
4000,0
3000
2000
1500
1000
650,0
cm-1
Fig. 3. IR spectra of derivative 5 and its intermediates recovered after heating to
100 °C and 170 °C respectively, compared with the IR of derivative 7.
Further support comes from the 13C NMR spectra of 7 and 8, val-
ues of 1J(Sn–C) being 925 and 901 Hz, respectively. In fact, on the basis
of the empirical relation h(C–Sn–C) = 0.178 ꢂ |1J(13C–119Sn)| +
14.74, derived by Howard for octahedral dialkyltin complexes of
type R2SnCh2 (R = alkyl, Ch = bidentate ligand) [25], the calculated
C–Sn–C angles for 7 and 8 are 180 and 175° (angles calculated from
this relationship have a standard error calculated as l2°).
S
Ph
Sn
S
Ph
O
O
O
Ph
Me
O
Sn Ph
Ph
Me
Ph
N
N
N
CDCl3
N
In addition, 119Sn NMR spectra of 7 and 8 show unique reso-
nances at ꢁ323 and ꢁ315 ppm, respectively, in close agreement
with those of bis(acylpyrazolonate)dimethyltin(IV) derivatives
previously reported and structurally characterized [9].
2
X
X
3.4. Thermal studies
R
Sn
R
R
O
O
O
Me
R
+ H2O
OH2
O
Sn
Derivatives 1–6 display low apparent melting/decomposition
points, within the range 118–136 °C. However thermal studies car-
ried out with TGA-DTA techniques have shown a more complex
behaviour on heating. In particular derivatives 3–6 undergo
decomposition with the formation of different substances.
Detailed thermal studies have been performed for all deriva-
tives 1–6 in the temperature range 30–500 °C under an inert atmo-
sphere of dry nitrogen. The data indicate that anhydrous
triphenyltin(IV) derivatives 1 and 2 are stable to decomposition
Me
N
N
N
CDCl3
R
R
N
3, X = O, R = Bun
4, X = S, R = Bun
6, X = S, R = Me
Scheme 4.

104
C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
Table 1
Metal atom environments, 1, (the two values in each entry are for molecules n = 1 and
2).
Atoms
Parameter
Atoms
Parameter
Distances (Å)
Sn(n)–O(n41)
2.478(3),
2.364(3)
2.058(2),
2.079(2)
1.255(4),
1.273(4)
1.298(4),
1.298(4)
Sn(n)–C(n51)
Sn(n)–O(n61)
Sn(n)–C(n71)
2.141(3),
2.149(3)
2.162(3),
2.145(3)
2.123(4),
2.133(3)
Sn(n)–O(n5)
O(n41)–C(n41)
O(n5)–C(n5)
Angles (°)
O(n41)–Sn(n)–
O(n5)
76.19(9),
77.24(9)
O(n5)–Sn(n)–
C(n51)
118.8(1),
123.0(1)
O(n41)–Sn(n)–
C(n51)
O(n41)–Sn(n)–
C(n61)
O(n41)–Sn(n)–
C(n71)
Sn(n)–O(n41)–
C(n41)
81.1(1), 82.2(1)
O(n5)–Sn(n)–
C(n61)
O(n5)–Sn(n)–
C(n71)
C(n51)–Sn(n)–
C(n61)
C(n51)–Sn(n)–
C(n71)
86.4(1), 84.4(1)
Fig. 4. TGA spectra of derivatives 5 and 7.
162.5(1),
160.8(1)
81.0(1), 85.4(1)
108.1(1),
109.7(1)
106.1(1,
103.9(1)
123.3(1),
121.0(1)
106.8(1),
106.0(1)
129.5(2),
135.1(2)
125.4(2),
132.9(2)
Sn(1)–O(n5)–
C(n5)
C(n61)–Sn(n)–
C(n71)
Interplanar dihedral angles (°) and atom deviations (dÅ)
C3O2/C3N2
Sn/C3O2
9.0(1), 5.0(2)
0.790(4),
C3N2/C6
C3N2/C4O
31.0(2), 21.6(2)
39.7(2), 28.0(2)
0.002(5)
Torsion angles (°) (carbon atoms denoted by number only)
O(n41)–Sn(n)–
n51–n52
O(n41)–Sn(n)–
n61–n62
ꢁ152.6(3),
O(n5)–Sn(n)–
n51–n52
O(n5)–Sn(n)–
n61–n62
ꢁ83.8(3),
ꢁ165.7(3)
ꢁ96.4(3)
39.1(6), 40.2(5)
45.6(3), 56.2(3)
O(n41)–Sn(n)–
n71–n72
ꢁ68.4(3),
ꢁ63.0(3)
O(n5)–Sn(n)–
n71–n72
ꢁ140.5(3),
ꢁ137.7(3)
Table 2
Metal atom environment, 6.
Atoms
Parameter
Atoms
Parameter
Distances (Å)
Sn–C(10)
Sn–C(20)
Sn–C(30)
2.1380(8)
2.1227(8)
2.1259(9)
Sn–O(1)
Sn–O(5)
2.3350(6)
2.2143(5)
Angles (°)
O(1)–Sn–C(10)
O(1)–Sn–C(20)
O(1)–Sn–C(30)
C(10)–Sn–C(20)
C(10)–Sn–C(30)
Sn–O(5)–C(5)
85.57(3)
86.96(3)
90.06(3)
125.34(4)
116.96(4)
119.72(4)
O(5)–Sn–C(10)
O(5)–Sn–C(20)
O(5)–Sn–C(30)
O(1)–Sn–O(5)
C(20)–Sn–C(30)
93.17(3)
90.15(3)
94.48(3)
175.36(2)
117.11(4)
Torsion angles (°) (carbon atoms denoted by number only)
5–N(1)–11–12
ꢁ44.3(1)
5–4–41–42
4–41–42–46
19.6(1)
16.3(1)
Fig. 5. Projection of molecule 1 of compound 1 quasi-normal to the acylpyrazol-
onate coordination plane (molecule 2 is similar). Non-hydrogen atoms are shown
with 50% probability amplitude displacement envelopes; hydrogen atoms have
arbitrary radii of 0.1 Å.
ꢀ
O(1), H(1A)ꢀꢀꢀO(41)(x; 1 ꢁ y, 1ꢁz) 2.6626(9), 1.86(1) (O–H 0.82(1) Å); O(1),
H(1B)ꢀꢀꢀN(2)(x, 3/2 ꢁ y, z ꢁ ½) 2.7645(9), 1.91(2) (O–H 0.87(2) Å).
correspondence between experimental and calculated weight
losses. Such thermal behaviour is typical and well known for alkyl-
tin(IV) complexes with O- or S-containing ligands [26].
up to 180 and 140 °C, respectively, derivative 1 showing at 122.0 °C
and 178.6 °C endothermic events assignable to fusion (the former)
and decomposition (the latter), whereas derivative 2 seems to pro-
gressively decompose without a real fusion. Final black residues of
more than 40% weight are probably a mixture of SnO (or SnS for 2)
and organic uncombusted material. By contrast, thermal runs of
derivatives 3 and 5 containing the Qfur ligand leave a residue cor-
responding to SnO, whereas for 4 and 6 with the sulfur-containing
Qthi ligand, the final residue is SnS, as confirmed by the good
The aquo Bun3Sn(IV) derivatives 3–4 lose their coordinated
water, endothermal dehydration taking place in a single step with-
in the range 80–100 °C (see Fig. 2), as confirmed by comparison of
theoretical and experimental values of percentage weight reduc-
tion. Further support is provided by the close correspondence of
the IR spectra of the powders recovered after heating derivatives
3–4 to 100 °C, with those of the starting compounds, the only

C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
105
Fig. 6. (a) Projection of the molecule of 6; (b) hydrogen-bonding in 6, showing the formation of a polymer of dimers, along c.
difference being the disappearance of the broad absorption due to
Sn-coordinated water in the range from 3100 to 3250 cmꢁ1. After
dehydration, other endothermic events are observed at higher
temperatures, probably due to melting, with decomposition of
anhydrous (Q)SnBu3 substances.
one equivalent of dichlorodimethyltin(IV) in methanol in the
presence of sodium methoxide (Scheme 2). Their analytical and
spectral data are the same of those of the intermediates of
decomposition of 5 and 6 recovered after a thermal run stopped
at 170 °C.
Trimethyltin(IV) derivatives 5 and 6 show a different thermal
behaviour with respect to the previous. Both display two consec-
utive plateaus, one starting at ca. 100 °C and the other at ca.
160 °C for 5 and at 150 °C for 6. After these steps, the percentage
loss of weight corresponds to the liberation of H2O and of one
half of an SnMe4 component, with concomitant formation of
intermediate species, which have been characterized by IR and
proton NMR as the bis(acylpyrazolonate)dimethyltin(IV) com-
pounds 7 and 8 (Scheme 2). Derivatives 7 and 8 have also been
prepared by interaction between two equivalents of HQfur and
We have studied in detail the thermal decomposition of 5 and
its rearrangement into the derivative (Qfur)2SnMe2 (7).
By the comparison of the IR spectra of the two intermediates,
recovered after heating at 100 and 170 °C, with those of the start-
ing derivative 5 and of derivative 7 (Fig. 3) we observe that the IR of
the intermediate recovered after the first step is exactly compara-
ble with the IR of derivative 7 synthesized using Me2SnCl2 as reac-
tant. Hence, during this first thermal step the elimination of the
water molecule and formation of the dimethyltin(IV) complex is
essentially complete.

106
C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
In the second step we have melting/decomposition in the
adducts are monohydrated aquo compounds with general for-
mula (Q)SnR3(OH2), with Q acting in a monodentate fashion
through only one carbonyl arm, the other being involved in a
hydrogen-bonding network with neighbouring water molecule
components. The tin atoms are in trigonal-bipyramidal environ-
ments, with the water molecules directly bonded to the tin
atoms. Such Sn–OH2 bonds are broken in solution and tetrahedral
OSnC3 species formed. After some days on standing in solution
the trimethyltin(IV) compounds slowly decompose into
(Q)2SnMe2 derivatives and SnMe4. Such decomposition can be in-
duced by heating, with release of H2O and volatile SnMe4 within
the range 80–100 °C. Dimethyltin(IV) derivatives (Q)2SnMe2 have
been also synthesized from HQ and Me2SnCl2 in basic methanol
and exist as skewed trans-octahedral compounds, both in the so-
lid state and solution.
range 172–176 °C, corresponding to the melting with decomposi-
tion observed in the TGA spectrum of derivative 7. From compar-
ison of the TGA spectra of 5 and 7 we observe the correspondence
of the curves after 170 °C, with two typical inflection points at ca.
290 and 330 °C (Fig. 4). An analogous thermal behaviour has been
found for derivative 6, which transforms into the corresponding
dimethyltin(IV)bis(acylpyrazolonate) compound 8. Also in this
case we have confirmed the transformation by comparison of
IR, proton NMR and TGA-DTA spectra of the intermediate recov-
ered by stopping the thermal run of 6 at 140 °C and those of
derivative (Qthi)2SnMe2 (8) synthesized by using Me2SnCl2 as
reactant.
3.5. Structure determination of [(Qfur)SnPh3] (1) and (Qthi)SnMe3(OH2)
(6)
Acknowledgment
The results of the single crystal X-ray structure determinations
of derivatives 1 and 6 are consistent with their formulation as
(Qfur)SnPh3 and (Qthi)SnMe3(OH2), respectively. In 1, the pyrazolate
ligand is O,O0-bidentate and the complex mononuclear, with five-
coordinate O2SnC3 metal atom environments. Two full indepen-
dent molecules, devoid of crystallographic symmetry, comprise
the asymmetric unit of the structure, representative molecule 1
being shown in Fig. 5, with metal atom coordination environments
presented comparatively in Table 1. A number of the latter differ
rather surprisingly between the two molecules, indicating a rather
flexible array, cf. the two similar complexes defined in the studies
of refs. [27,28]. (See also Ref. [29] where two such molecular units
are linked by a bifunctional ligand). Differences in Sn(n)–O(n41) cf.
Sn(n)–O(n5) correlate with differences observed in the associated
C–O distances; the dispositions of the three phenyl rings persist
across both molecules. The exocyclic angles at C(n42) of the pen-
dant furyl rings are very disparate (C(n41)–C(n42)–C(n46);
O(n43) 132.8(3), 130.8(4), 116.8(3), 119.8(3)°), regardless of
whether O(n43) lies cis to O(n41), as is the case in molecule 1, or
trans (molecule 2). The coordination environments are more nearly
trigonal-bipyramidal than square pyramidal, although the large
angle (O(n41)-Sn-C(n61), 152.5(1), 160.8(1)°) is well removed
from linearity in each case.
On passing to 6, the more feebly bound carbonyl oxygen atom is
detached, being supplanted by a more strongly bound water mol-
ecule. In the structure of 6, a single molecule of (Qthi)SnMe3(OH2),
devoid of crystallographic symmetry, comprises the asymmetric
unit of the structure. The tin atom coordination environment is
again quasi-trigonal bipyramidal, with the three methyl groups
in the equatorial plane (Table 2, Fig. 6(a)). Such an environment
has been defined previously in an earlier determination of a similar
complex with a different ‘Q’ ligand in ref. [9d], the present offering
superior precision. Hydrogen-bonds from the water molecule (Ta-
ble 2) link (A) centrosymmetrically to the ligand carbonyl oxygen
atoms, forming a dimer, the other (B) linking to the nitrogen atom
of a c-glide related unit, forming a polymer of dimers in that direc-
tion (Fig. 6(b)).
Financial support by Università degli Studi di Camerino and
Valle-Esina SpA (grant to Alessandro Marinelli) is gratefully
acknowledged.
Appendix A. Supplementary material
Full cif depositions (excluding structure factor amplitudes)
CCDC 779873 and 799085 can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.ica.2010.12.002.
References
[1] M. Gielen, A. Davies, K. Pannell, E. Tiekink, Tin Chemistry: Fundamentals,
Frontiers, and Applications, John Wiley and Sons, Chichester, United Kingdom,
2008.
[2] S.K. Hadjikakou, N. Hadjiliadis, Coord. Chem. Rev. 253 (2009) 235.
[3] M. Hoch, Appl. Geochem. 16 (2001) 719.
[4] (a) V. Chandrasekhar, S. Nagendran, V. Baskar, Coord. Chem. Rev. 235 (2002) 1;
(b) L. Pellerito, L. Nagy, Coord. Chem. Rev. 224 (2002) 111.
[5] (a) C. Pettinari, Scorpionates II: Chelating Borate Ligands, World Scientific
Group, Imperial College Press, London, United Kingdom, 2008.;
(b) C. Pettinari, C. Santini, Polypyrazolylborate and Scorpionate Ligands, in:
Comprehensive Coordination Chemistry II, vol. 1, Elsevier, 2003, p. 159
(Chapter 1.10).
[6] (a) C. Pettinari, R. Pettinari, Coord. Chem. Rev. 249 (2005) 663;
(b) C. Pettinari, R. Pettinari, Coord. Chem. Rev. 249 (2005) 525.
[7] C. Pettinari, R. Pettinari, Coord. Chem. Rev. 249 (2005) 2909.
[8] Y.A. Zolotov, N.M. Kuzmin, Extraction of Metals by Acylpyrazolones, Nauka,
Moscow, Russia, 1977.
[9] (a) C. Pettinari, F. Marchetti, A. Gregori, A. Cingolani, J. Tanski, M. Rossi, F.
Caruso, Inorg. Chim. Acta 257 (1997) 37;
(b) C. Pettinari, F. Marchetti, A. Cingolani, A. Lorenzotti, E. Mundorff, M. Rossi, F.
Caruso, Inorg. Chim. Acta 262 (1997) 33;
(c) F. Caruso, D. Leonesi, F. Marchetti, E. Rivarola, M. Rossi, V. Tomov, C.
Pettinari, J. Organomet. Chem. 519 (1996) 29;
(d) F. Marchetti, C. Pettinari, A. Cingolani, G. Gioia Lobbia, A. Cassetta, L. Barba,
J. Organomet. Chem. 517 (1996) 141;
(e) F. Caruso, M. Rossi, F. Marchetti, C. Pettinari, Organometallics 18 (1999)
2398;
(f) C. Pettinari, F. Marchetti, A. Cingolani, A. Gindulyte, L. Massa, M. Rossi, F.
Caruso, Eur. J. Inorg. Chem. (2001) 2171.
[10] C. Pettinari, F. Caruso, N. Zaffaroni, R. Villa, F. Marchetti, R. Pettinari, C. Phillips,
J. Tanski, M. Rossi, J. Inorg. Biochem. 100 (2006) 58.
4. Conclusions
[11] B.S. Jensen, Acta Chem. Scand. 13 (1959) 1890. 1347, 1668.
[12] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[13] M.J. O’Connell, C.G. Ramsay, P.J. Steel, Aust. J. Chem. 38 (1985) 401.
[14] (a) S. Saxena, R. Bohra, A.K. Rai, Inorg. Chim. Acta 172 (1990) 191;
(b) C. Pettinari, F. Marchetti, A. Cingolani, D. Leonesi, E. Mundorff, M. Rossi, F.
Caruso, J. Organomet. Chem. 557 (1998) 187.
We have synthesized novel triorganotin(IV) derivatives, with
acylpyrazolonate Q ligands incorporating oxygen- (Qfur) and sul-
fur-heterocycles (Qthi) in their acyl fragments, by direct reaction
between HQ and (R3Sn)2O in benzene (R = Ph or Bu) and between
HQ and Me3SnCl in benzene/methanol in the presence of NaOMe.
The triphenyltin(IV) adducts are anhydrous derivatives of formula
(Q)SnPh3 where Q is O,O0-bidentate and tin is five-coordinate in
the solid state. By contrast, the tributyl- and trimethyl-tin(IV)
[15] (a) J.R. May, W.R. McWhinnie, R.C. Poller, Spectrochim. Acta A 27 (1971) 969;
(b) A.L. Smith, Spectrochim. Acta A 24 (1967) 695;
(c) M.S. Dance, W.R. McWhinnie, R.C. Poller, J. Chem. Soc., Dalton Trans. (1976)
2349;
(d) D.H. Whiffen, J. Chem. Soc. (1956) 1350.

C. Pettinari et al. / Inorganica Chimica Acta 367 (2011) 98–107
107
[16] (a) B.Y.K. Ho, J.J. Zuckermann, Inorg. Chem. 12 (1973) 1552;
(b) R. Okawara, D.E. Webster, E.G. Rochow, J. Am. Chem. Soc. 82 (1960) 3287;
(c) G.K. Sandhu, G. Kaur, J. Holecek, A. Lycka, J. Organomet. Chem. 345 (1988)
51.
[17] M.F. Mahon, K.C. Molloy, B.A. Omotowa, M.A. Mesubi, J. Organomet. Chem. 511
(1996) 227.
[18] B. Wreckmeyer, Ann. Rep. NMR Spectrosc. 16 (1985) 73.
[19] (a) T.P. Lockhart, W.F. Manders, Inorg. Chem. 25 (1986) 892;
(b) J. Holecek, A. Lycka, Inorg. Chim. Acta 118 (1986) L15;
(c) W.F. Howard, R.W. Crecely, W.H. Nelson, Inorg. Chem. 24 (1985) 2204.
[20] F. Marchetti, C. Pettinari, R. Pettinari, unpublished results.
[21] G.M. Bancroft, B.W. Davies, N.C. Payne, T.K. Sham, J. Chem. Soc., Dalton Trans.
(1975) 973.
[23] (a) J. Holecek, A.J. Lycka, Inorg. Chim. Acta 118 (1986) L15;
(b) J. Holecek, M. Nadvornik, K. Handlir, A.J. Lycka, Organomet. Chem. 241
(1983) 177.
[24] (a) M. Nadvornik, J. Holecek, K. Handlir, A. Lycka, J. Organomet. Chem. 275
(1984) 43;
(b) P.J. Smith, R.F.M. White, L. Smith, J. Organomet. Chem. 40 (1972) 341.
[25] W.F. Howard, R.W. Crecely, W.H. Nelson, Inorg. Chem. 24 (1985) 2204.
[26] M. Nath, Sulaxna, X. Song, G. Eng. Spectrochim. Acta Part A 64 (2006) 148.
[27] F. Marchetti, C. Pettinari, A. Cingolani, L. Brocanelli, M. Rossi, F. Caruso, J.
Organomet. Chem. 580 (1999) 344.
[28] F. Marchetti, C. Pettinari, A. Cingolani, R. Pettinari, M. Rossi, F. Caruso, J.
Organomet. Chem. 645 (2002) 134.
[29] C. Pettinari, F. Marchetti, R. Pettinari, A. Cingolani, A. Drozdov, S. Troyanov, J.
Chem. Soc., Dalton Trans. (2002) 188.
[22] K. Kawakami, R. Okawara, J. Organomet. Chem. 6 (1966) 249.