Organometallic coordination polymers: Sn(IV) derivatives with the bis(triazolyl)methane ligand

Article abstract of DOI:10.1016/j.ica.2010.05.031

Several alkyl- or aryl-tin(IV) halides of general formula SnR _nX_4-n (n = 0-2; R = Me, Et, ⁿBu, ^tBu, Ph; X = Cl, Br), possessing Lewis acidic character, have been reacted with the polydentate N-donor ligand bis(1

Full text of DOI:10.1016/j.ica.2010.05.031

Inorganica Chimica Acta 363 (2010) 3733–3741
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Organometallic coordination polymers: Sn(IV) derivatives with the
bis(triazolyl)methane ligand
b,
b
b
Norberto Masciocchi a, , Claudio Pettinari
, Riccardo Pettinari , Corrado Di Nicola ,
*
**
Alessandro Figini Albisetti c
a Dipartimento di Scienze Chimiche e Ambientali, Università dell’Insubria, via Valleggio 11, 22100 Como, Italy
b Dipartimento di Scienze Chimiche, Università di Camerino, via S.Agostino 1, 62032 Camerino, Italy
c Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Università di Milano, via Venezian 21, 20133 Milano, Italy
a r t i c l e i n f o
a b s t r a c t
Several alkyl- or aryl-tin(IV) halides of general formula SnRnX4ꢀn (n = 0–2; R = Me, Et, nBu, tBu, Ph; X = Cl,
Br), possessing Lewis acidic character, have been reacted with the polydentate N-donor ligand bis(1,2,4-
triazolyl)methane (Btm), affording Btm(SnRnCl4ꢀn) complexes. (Btm)2SnnBu2Br2 and (Btm)SnnBu2(NO3)2
are also reported. These materials were characterized by elemental analyses, IR and 1H (and, in selected
cases, 119Sn) NMR spectroscopy, and, were possible, ab initio X-ray powder diffraction methods. The crys-
tal structures determined by the latter method showed that Btm ligands, in the exobidentate mode, link
Sn(IV) fragments which lie 9.5–11.2 Å apart (depending on the Btm conformation and on the local metal
stereochemistry), in one-dimensional chains packed in parallel bundles. The main geometrical features of
these 1D polymers are compared with those of the bis(imidazolyl)methane complexes and of the known
Btm derivative, Btm(Ph2SnBr2). Interestingly, the expected isomorphous structures for selected couples
was not found, as if very subtle energetic differences were driving the crystallization of these species into
different structure types.
Article history:
Received 1 March 2010
Received in revised form 11 May 2010
Accepted 15 May 2010
Available online 23 May 2010
Keywords:
Organometallic polymers
Nitrogen ligands
Powder diffraction
Tin
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
Recently, our interest has shifted from carbonylic species to
new polytopic ligands, capable of bridging metal centers at differ-
In the last decades, one-dimensional coordination polymers
have been the subject of several investigations, for their peculiar
structures, reactivity and functional activity, which have been of-
ten attributed to the cooperativity of the different metal coordina-
tion spheres, enhancing, or generating, new functional properties
[1]. This is particularly true if the metal arrangement is nearly
colinear, as beautifully demonstrated by the Fe(II) spin crossover
systems (showing hysteretic behavior near RT) [2], the Cu(II) pyr-
azolate (vapochromic) polymers [3,4] and, long time ago, by the
electron-conducting (doped) K2Pt(CN)4 materials [5]. Less investi-
gated are monodimensional organometallic polymers, some of
which could be characterized by X-ray powder diffraction (XRPD)
methods only, eventually disclosing new, or unexpected, connec-
tivity, conformation and stoichiometry. For example, the elusive
structures of the [Ru(CO)4]n [6], [Ru(2,20-bipyridine)(CO)2]n [7],
[PdCl(acetonyl)]n [8], [HRe(CO)4]n and [HRe(CO)4]6 [9] species were
all determined from laboratory XRPD data on less-than-ideal poly-
crystalline materials, not affording single-crystals of suitable
quality.
ent distances, thanks to the exobidentate mode of N-heterocyclic
rings, such as pyrazolates, imidazolates and pyrimidinolates. A par-
tial summary of our studies can be found in Refs. [10–12]. Worthy
of note, among the many species prepared during this ongoing pro-
ject, interesting functional materials could be prepared: molecular
magnets [13]; second harmonics generation-active polymers [14];
nanoporous MOFs with high gas storage capacity and size-selective
catalytic activity [15].
Our latest results were focused on the coordination chemistry
of the new bis(imidazolyl)methane ligand [16] (Bim, see Scheme 1),
which was coupled to a number of metal centers: transition metal
ions (Rh, Zn, Cd and Hg) [17–19] and main group elements (Sn)
[20]. This recent work of ours has been substantially augmented
by the publications of Chen and Cui, who used also other transition
metal ions [Ag(I), Mn(II) Fe(II), Co(II), Ni(II) and Cu(II)], also in com-
bination with complex carboxylates [21–23]. Aiming at better
comprehending the subtle factors driving the formation of these
polymers, in the last year we shifted our attention to the similar
bis(1,2,4-triazolyl)methane ligand (Btm, see Scheme 1), which,
bearing two additional nitrogen atoms on the heterocyclic ring,
may show an increased flexibility and coordination versatility.
As an initial set of compounds, we prepared Sn(IV) organome-
tallic polymers, to be structurally compared with the Bim analogs
* Corresponding author.
** Corresponding author.
E-mail address: norberto.masciocchi@uninsubria.it (N. Masciocchi).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.05.031

3734
N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
reported by us in Ref. [20]. Indeed, organotin polymers are increas-
ingly attracting the attention of many for their potential industrial
application and biological activities [24,25], since they are effective
against wood decay fungi and marine borers but also widely used
in self-polishing paints [26]. On the other hand, 1,2,4-triazole is
associated with diverse pharmacological activities such as analge-
sic, antiasthmatic, diuretic, antihypersensitive, anticholinergic,
antibacterial, antifungal and anti-inflammatory activity [27–31]
and, thanks to the presence of the pyridinic nitrogen atoms, is able
to form metal coordination polymers, of still unknown structure
[32], or fully characterized, as in the recently reported lead acetate
and hydroxo-copper derivatives [33,34]. Thus, a combination of
these two functions within the same compound may, in principle,
lead to an increasing antimicotic effect.
The modification of poly(pyrazolyl)alkane ligands through
replacement of the pyrazolyl by a triazolyl ring has been originally
performed by Elguero and coworkers in 1982 [35]. Unfortunately,
the coordination chemistry of Btm is still poorly developed, mainly
due to the lack of conventional single-crystal structural analyses,
as a consequence of the poor solubility of its (likely polymeric) me-
tal complexes. In this contribution, we present the synthesis of sev-
eral Btm-based organotin polymers, a few of which have been
structurally characterized using state-of-the-art (less conven-
tional) structural methods (employing laboratory X-ray powder
diffraction data), coupled to ancillary elemental, IR and 1H and
119Sn NMR analyses. Our results will be compared with those re-
ported by Tang et al. who described the crystal and molecular
structure of the polymeric Btm(Ph2SnBr2) derivative [36]. In order
to improve the legibility of this paper, also in conjunction with the
previously communicated results, the complete labeling and nam-
ing of the Sn(IV) polymers is hereafter reported:
Varian 400 NMR spectrometer (400 for 1H and 149.2 MHz for 119Sn,
respectively). Referencing is relative to TMS (1H) and Me4Sn
(
amount of compound in 0.5 ml of solvent. Peak multiplicities are
abbreviated: singlet, s; doublet, d; triplet, t; quartet, q; and multi-
plet, m. Melting points are uncorrected and were taken on an SMP3
Stuart scientific instrument and on a capillary apparatus.
119Sn). NMR samples were prepared by dissolving a suitable
2.2. Syntheses
2.2.1. Btm
The ligand Btm has been prepared by the literature methods
[37], and has been recrystallized from hot chloroform. Mp 165–
168 °C. Anal. Calc. for C5H6N6: C, 40.00; H, 4.03; N, 55.97. Found:
C, 40.02; H, 4.20; N, 56.03%. IR (nujol, cmꢀ1): 3181br, 3115w,
3106w, 1555w, 1508m, 1500m 391m, 383m, 360w br, 279w. 1H
NMR (CDCl3, 293 K): d, 6.44 (s, 2H, CH2Btm), 7.99 (s, 2H, CHBtm),
8.42 (s, 2H, CHBtm). 1H NMR (CD3OD, 293 K): d, 6.68 (s, 2H, CH2Btm),
8.03 (s, 2H, CHBtm), 8.80 (pt, 2H, CHBtm). 1H NMR (DMSO-d6, 293 K):
d, 6.7 (s, 2H, CH2Btm), 8.1 (s, 2H, CHBtm), 8.9 (pt, 2H, CHBtm). 1H NMR
(acetone-d6, 293 K): d, 6.7 (s, 2H, CH2Btm), 8.1 (s, 2H, CHBtm), 8.9 (pt,
2H, CHBtm).
2.2.2. Btm(SnMe2Cl2) (1Btm
)
To a stirred ethanol solution (20 mL) of Me2SnCl2 (0.219 g,
1.0 mmol) was added an ethanol solution (20 mL) of bis(triazol-
1-yl)methane (Btm) (0.150 g, 1.0 mmol). The solution was stirred
for 48 h under N2 at room temperature. Upon diethyl ether addi-
tion a colorless precipitate formed which was isolated by filtration
and dried in vacuum. The residue obtained was washed with 5 mL
of diethyl ether and shown to be compound 1Btm (0.332 g,
0.90 mmol, yield 90%). M.p. 167–171 °C dec. Anal. Calc. for
C7H12Cl2N6Sn: C, 22.73; H, 3.27; N, 22.72. Found: C, 22.93; H,
3.34; N, 22.70%. IR (nujol, cmꢀ1): 3117w, 3060w; 1547m, 1538m,
Btm(SnMe2Cl2), 1Btm
Btm(SnEt2Cl2), 2Btm
Btm(SnnBu2Cl2), 3Btm
Btm(SnPh2Cl2), 4Btm
Btm(SnMeCl3), 5Btm
Btm(SnPhCl3), 6Btm
Btm(SntBu2Cl2), 7Btm
Btm(SnCl4), 8Btm
. . .
. . .
1502m
br
t
(C C, C N), 353m, 205m, 175m, 575m t(Sn–C), 240s
•
•
t
(Sn–Cl). 1H NMR (DMSO-d6, 293 K): d, 1.04 (s, 6H, CH3Sn
,
1J(119Sn–1H): 114 Hz; 1J(117Sn–1H): 109 Hz), 6.7(s, 2H, CH2Btm),
8.0 (s, 2H, CHBtm), 8.9 (s, 2H, CHBtm). 1H NMR (acetone-d6, 293 K):
d, 1.2 (s, 6H, CH3Sn
,
1J(119Sn–1H): 84 Hz; 1J(117Sn–1H): 80 Hz), 6.7
(s, 2H, CH2Btm), 7.9 (s, 2H, CHBtm), 8.7 (s, 2H, CHBtm). 119Sn NMR
Btm(SnBr4), 9Btm
(CDCl3, 293 K): +110 ppm. Km (DMSO, 293 °C): 9.4
(1.0 ꢁ 10ꢀ3 M).
lS
(Btm)2SnnBu2Br2, 10Btm
BtmSnnBu2(NO3)2, 11Btm
2.2.3. Btm(SnEt2Cl2) (2Btm
)
while the bis(imidazolyl)methane (Bim) analogs will be referred to
by the corresponding XBim labels.
Btm (0.158 g, 1.0 mmol) was added to a methanol solution
(20 mL) containing Et2SnCl2 (0.247 g, 1.0 mmol). The solution
was stirred for 5 days under N2 at room temperature. Slow evapo-
ration of the solution yields colorless crystals which were filtered,
dried in vacuum and shown to be compound 2Btm (0.120 g,
0.30 mmol, yield 30%). M.p. 178–180 °C dec. Anal. Calc. for
2. Experimental
2.1. Materials and methods
C9H16Cl2N6Sn: C, 27.17; H, 4.05; N, 21.12. Found: C, 27.23; H,
4.21; N, 21.03%. IR (nujol, cmꢀ1): 3140w, 3116w; 1513m
t(C C,
. . .
•
. . .
All chemicals and reagents were of reagent grade quality and
were used as received without further purification. All solvents
were distilled prior to use. Dichloromethane was freshly distilled
from CaH2. Other solvents were dried and purified by standard pro-
cedures. The samples were dried in vacuo to constant weight
(293 K, 0.1 Torr). Elemental analyses were carried out in-house
with a Fisons Instruments 1108 CHNSO-elemental analyzer. IR
spectra from 4000 to 370 cmꢀ1 were recorded with a Perkin–Elmer
Spectrum One FT-IR instrument. The solid samples were analyzed
on the single reflection ATR accessories. The solid has been placed
on the crystal area, the pressure arm being positioned over the
crystal/sample area. IR spectra from 700 to 150 cmꢀ1 were re-
corded with a Perkin–Elmer System 2000 FT-IR instrument. 1H
and 119Sn NMR solution spectra were recorded on a Mercury-Plus
C
t
N), 535m, 485br, 373m, 289m, 279m, 267m, 245sh, 226sh
•
(Sn–Cl). 1H NMR (CDCl3, 293 K): d, 1.45 (t, 6H, CH3Sn
170 Hz, 1.77 (q, 4H, CH2Sn
2J(119Sn–1H): 88 Hz), 6.44 (s, 2H,
CH2Btm), 7.99 (s, 2H, CHBtm), 8.42 (s, 2H, CHBtm). 1H NMR (CD3OD,
,
3J(Sn–1H):
,
293 K): d, 1.38 (t, 6H, CH3Sn, ,
3J(Sn–1H): 170 Hz), 1.67 (q, 4H, CH2Sn
2J(Sn–1H): 88 Hz), 6.67 (s, 2H, CH2Btm), 8.03 (s, 2H, CHBtm), 8.79 (s,
2H, CHBtm). 119Sn NMR (CDCl3, 293 K): +121 ppm. Km (DMSO,
293 °C): 7.3
l
S (1.0 ꢁ 10ꢀ3 M).
2.2.4. Btm(SnnBu2Cl2) (3Btm
)
Btm (0.150 g, 1.0 mmol) was added to a dichloromethane solu-
tion (20 mL) containing nBu2SnCl2 (0.303 g, 1.0 mmol). The solu-
tion was stirred overnight. Upon addition of diethyl ether a
colorless precipitate formed which was filtered off and washed

N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
3735
with 20 ml of n-hexane and shown to be compound 3Btm (40%
yield). From the mother liquor very small colorless crystals were
also obtained that were identified as 3Btm. M.p. 94–95 °C dec. Anal.
Calc. for C13H24Cl2N6Sn: C, 34.40; H, 5.33; N, 18.51. Found: C,
34.24; H, 5.55; N, 18.34%. IR (KBr, cmꢀ1): 3115w, 3022w, 2970w,
7.2–7.5 (m, 2H, Sn–C6H5), 8.0, 8.1, 8.8, 8.9 (s br, 2H, CHBtm). Km
(DMSO, 293 °C): 18.0
l
S (0.9 ꢁ 10ꢀ3 M).
2.2.8. [Btm(SntBu2Cl2)] (7Btm
)
Bis(triazol-1-yl)methane (Btm) (0.150 g, 1.0 mmol) was added
to a methanol solution (20 mL) containing tBu2SnCl2 (0.303 g,
1.0 mmol). The solution was stirred overnight and then slowly
evaporated until a colorless precipitate formed which was filtered
off and washed with 20 ml of diethyl ether and shown to be com-
pound 7Btm (45% yield). M.p. 143–145 °C dec. Anal. Calc. for
. . .
t(C C, C N), 1446w, 1399w, 1277m,
•
. . .
2923w, 2909w; 1512m
•
1195m, 1114s, 1020m, 982m, 951m, 916w, 778m, 736s, 660s. 1H
NMR (CDCl3, 293 K): d, 0.93t, 1.4m, 1.8m, 1.9m (18H, C4H9Sn),
6.44 (s, 2H, CH2Btm), 7.97 (s, 2H, CHBtm), 8.41 (s, 2H, CHBtm). 1H
NMR (CDCl3, 293 K): d, 0.95t, 1.4m, 1.7m, 1.9m (18H, C4H9Sn),
6.67 (s, 2H, CH2Btm), 8.03 (s, 2H, CHBtm), 8.80 (s, 2H, CHBtm). Km
C
13H24Cl2N6Sn, C, 34.40; H, 5.33; N, 18.51. Found: C, 33.90; H,
5.42; N, 18.89. IR (nujol, cm-1): 3186w, 3111w, 3096w; 1515sh,
. . . . . .
(DMSO, 293 °C): 12.4
l
S (1.2 ꢁ 10ꢀ3 M).
1503m
t(C C, C N), 391m, 384m, 342s, 272w, 254m, 250m.
• •
1H NMR (CD3OD, 293 K): d, 1.46 (s, 18H, C4H9Sn 1J(119Sn–1H):
,
2.2.5. Btm(SnPh2Cl2) (4Btm
)
117 Hz, 1J(117Sn–1H): 112 Hz), 6.67 (s, 2H, CH2Btm), 8.03 (s, 2H,
CHBtm), 8.79 (s, 2H, CHBtm). 1H NMR (CDCl3, 293 K): d, 1.45 (s,
Btm (0.150 g, 1.0 mmol) was added to a methanol solution
(20 mL) containing Ph2SnCl2 (0.343 g, 1.0 mmol). A colorless pre-
cipitate immediately formed. The suspension was stirred for 12 h
under N2 at room temperature. The resulting colorless precipitate
was isolated by filtration and dried in vacuum. The residue ob-
tained was washed with 5 mL of diethyl ether, recrystallized from
ethanol and shown to be compound 4Btm (0.469 g, 0.95 mmol,
yield 95%). M.p. 166–167 °C dec. Anal. Calc. for C17H16Cl2N6Sn: C,
41.34; H, 3.26; N, 17.01. Found: C, 41.71; H, 3.20; N, 17.12%. IR (nu-
18H, C4H9Sn,
1J(119Sn–1H): 117 Hz, 1J(117Sn–1H): 112 Hz), 6.45 (s,
2H, CH2Btm), 7.97 (s, 2H, CHBtm), 8.45(s, 2H, CHBtm). Km (DMSO,
293 °C): 6.5
l
S (1.0 ꢁ 10ꢀ3 M).
2.2.9. Btm(SnCl4) (8Btm
)
Bis(triazol-1-yl)methane (Btm) (0.151 g, 1.0 mmol) was added
to a dichloromethane solution (20 mL) containing SnCl4 (0.26 g,
1.0 mmol). A colorless precipitate immediately formed. The sus-
pension was stirred for 4 h under N2 at room temperature. The
resulting colorless precipitate was isolated by filtration and dried
in vacuum. The residue obtained was washed with 5 mL of dichlo-
romethane, and shown to be compound 8Btm (0.250 g, 0.60 mmol,
yield 60%). M.p. 200 °C dec. Anal. Calc. for C5H6Cl4N6Sn, C, 14.62; H,
1.47; N, 20.47. Found: C, 15.05; H, 1.78; N, 20.53%. IR (cmꢀ1):
jol, cmꢀ1): 3117w; 1570w, 1540w, 1518m, 1508m
461m, 382w, 291s, 283s, 233s br
(Sn–Cl). 1H NMR (DMSO-d6,
t
(C C, C N),
. . .
. . .
•
•
t
293 K): d, 6.6, 6.7 (2s, 2H, CH2Btm), 7.2–7.5 (m, 10H, Sn–C6H5),
8.0, 8.1 (s, 2H, CHBtm), 8.8, 8.9 (s, 2H, CHBtm). 1H NMR (CD3OD,
293 K): d, 6.66 (2s, 2H, CH2Btm), 7.5 (m, 6H, Sn–C6H5, 1J(Sn–1H):
103 Hz), 7.9 (m, 4H, Sn–C6H5), 8.03 (s, 2H, CHBtm), 8.79 (s, 2H,
CHBtm). 119Sn NMR (DMSO-d6, 293 K), d: ꢀ402 ppm. 119Sn NMR
(CD3OD, 293 K), d: ꢀ241 ppm. Km (DMSO, 293 °C): 32.5
lS
. . .
t(C C, C N),
•
. . .
3142w, 3119w, 3027w; 1538m, 1530sh, 1519m,
•
(0.4 ꢁ 10ꢀ3 M).
390w, 320s t
(Sn–Cl), 190w, 165m. 1H NMR (DMSO-d6, 293 K): d,
6.63 (s, 2H, CH2Btm), 8.03 (s, 2H, CHBtm), 8.82 (s, 2H, CHBtm). 1H
NMR (DMSO-d6, 293 K): d, 6.6, 6.7 (s, 2H, CH2Btm), 8.0, 8.1, 8.8,
8.9, 9.0 (br, 4H, CHBtm).119Sn NMR (DMSO-d6, 293 K): ꢀ625,
2.2.6. Btm(SnMeCl3) (5Btm
)
To a stirred ethanol solution (20 mL) containing MeSnCl3
(0.240 g, 1.0 mmol) Btm (0.150 g, 1.0 mmol) was added. The sus-
pension was stirred for 2 h under N2 at room temperature. The
resulting colorless precipitate was isolated by filtration and dried
in vacuum. The residue obtained was washed with 5 mL of ethanol
and shown to be compound 5Btm (0.220 g, 0.56 mmol, yield 56%).
M.p. 257–258 °C dec. Anal. Calc. for C6H9Cl3N6Sn: C, 18.47; H,
2.32; N, 21.54. Found: C, 18.65; H, 2.54; N, 21.44%. IR (nujol,
ꢀ668. Km (DMSO, 293 °C): 78.4
l
S (0.7 ꢁ 10ꢀ3 M).
2.2.10. Btm(SnBr4) (9Btm
)
Btm (0.151 g, 1.0 mmol) was added to a dichloromethane solu-
tion (20 mL) containing SnBr4 (0.436 g, 1.0 mmol). A colorless pre-
cipitate immediately formed. The suspension was stirred for 4 h
under N2 at room temperature, then filtered off and the precipitate
dried in vacuum. The residue obtained was washed with 5 mL of
dichloromethane and shown to be compound 9Btm (0.423 g,
0.72 mmol, yield 72%). M.p. 300 °C dec. Anal. Calc. for C5H6Br4N6Sn:
cmꢀ1): 3139w, 3110w, 3060sh; 1539s, 1519br
536s, 406w, 334s, 289s
(Sn–Cl). 1H NMR (DMSO-d6, 293 K): d,
t
(C C, C N),
. . .
. . .
•
•
t
1.00 (s br, 3H, CH3Sn), 6.6, 6.7 (br, 2H, CH2Btm), 8.1, 8.15 (s br, 2H,
CHBtm), 8.8, 8.9 (s br, 2H, CHBtm). 1H NMR (DMSO-d6, 293 K): d,
,
1J(119Sn–1H): 133 Hz, 1J(117Sn–1H): 123 Hz),
C, 10.21; H, 1.03; N, 14.28. Found: C, 10.34; H, 1.25; N, 14.65%. IR
0.93 (s, 3H, CH3Sn
(nujol, cmꢀ1): 3126w, 3060w; 1608w, 1560w, 1540m
t(C C,
. . .
6.65 (s, 2H, CH2Btm), 8.04 (s, 2H, CHBtm), 8.84 (s, 2H, CHBtm). 119Sn
•
. . .
C
N), 403w, 392w, 286w, 231s, 221s, 212s t
(Sn–Br). 1H NMR
•
NMR (DMSO-d6, 293 K): ꢀ 450br. Km (DMSO, 293 °C): 13.5
(0.6 ꢁ 10ꢀ3 M).
lS
(CD3OD, 293 K): d, 6.79 (s, 2H, CH2Btm), 8.29 (s, 2H, CHBtm), 9.19
(s, 2H, CHBtm). Km (DMSO, 293 °C): 84.0
l
S (0.6 ꢁ 10ꢀ3 M).
2.2.7. Btm(SnPhCl3) (6Btm
Bis(triazol-1-yl)methane (Btm) (0.150 g, 1.0 mmol) was added
ethanol solution (20 mL) containing PhSnCl3 (0.303 g,
)
2.2.11. (Btm)2(SnnBu2Br2) (10Btm
Bis(triazol-1-yl)methane (Btm) (0.150 g, 1.0 mmol) was added
to a
dichloromethane solution (20 mL) containing nBu2SnBr2
)
to
a
1.0 mmol). A colorless precipitate immediately formed. The sus-
pension was stirred for 12 h under N2 at room temperature. The
resulting colorless precipitate was isolated by filtration and dried
in vacuum. The residue obtained was washed with 5 mL of diethyl
ether and 10 mL of methanol and shown to be compound 6Btm
(0.350 g, 0.77 mmol, yield 77%). M.p. 250 °C dec. Anal. Calc. for
(0.392 g, 1.0 mmol). The solution was stirred overnight. Upon addi-
tion of 15 mL of diethyl ether a colorless precipitate formed which
was filtered off and washed with 20 ml of n-hexane and shown to
be compound 10Btm (40% yield). M.p. 108 °C dec. Anal. Calc. for
C18H30Br2N12Sn, C, 31.20; H, 4.36; N, 24.25. Found: C, 31.57; H,
4.31; N, 24.57%. IR (KBr, cmꢀ1): 3115w, 3027w, 2965w, 2927w,
2857w; 1515m, 1454w, 1408w, 1384w, 1355w, 1268m, 1192m,
1115s, 1026m, 979m, 956m, 908m, 885m, 779m, 731s, 683m,
660s. 1H NMR (CDCl3, 293 K): d, 0.92t, 1.4m, 1.8m (18H, C4H9Sn),
6.44 (s, 4H, CH2Btm), 7.97 (s, 4H, CHBtm), 8.41 (s, 4H, CHBtm). 1H
NMR (CDCl3, 293 K): d, 0.96t, 1.43m, 1.8m (18H, C4H9Sn), 6.67
C
11H11Cl3N6Sn, C, 29.21; H, 2.45; N, 18.58. Found: C, 28.82; H,
2.42; N, 18.30%. IR (nujol, cmꢀ1): 3114w; 1574w, 1518m
t(C C,
. . .
•
. . .
C
N), 450m, 385w, 313s t(Sn–Cl), 293s, 264sh t(Sn–C), 232m,
•
193m. 1H NMR (CD3OD, 293 K): d, 6.67 (s, 2H, CH2Btm), 7.37 (m,
3H, Sn–C6H5), 7.84 (m, 2H, Sn–C6H5), 8.07 (s, 2H, CHBtm), 8.84 (s,
2H, CHBtm). 1H NMR (DMSO-d6, 293 K): d, 6.5s, 6.6s (br, 2H, CH2Btm),

3736
N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
Table 1
Crystal data and refinement details for the compounds 1Btm, 4Btm and 5Btm and their Bim counterparts (taken from Ref. [20]).
1Btm
4Btm
5Btm
1Bim
5Bim
Empirical formula
fw (g molꢀ1
Crystal system
SPGR, Z
a (Å)
C7H12Cl2N6Sn
369.83
monoclinic
C2/c, 4
15.2596(4)
11.8545(3)
8.5151(2)
90
119.410(2)
90
1341.84(6)
1.83
C17H16Cl2N6Sn
493.97
monoclinic
P21/n, 4
12.4477(6)
15.3044(9)
9.8471(5)
90
90.972(4)
90
1875.6(2)
1.74
C6H9Cl3N6Sn
390.25
C9H14Cl2N4Sn
361.80
monoclinic
P21/n, 4
15.333(1)
9.000(1)
10.650(1)
90
107.569(3)
90
1401.0(1)
1.71
C8H11C3N4Sn
450.33
monoclinic
C2, 2
10.706(2)
8.217(1)
8.077(1)
90
67.363(4)
90
655.8(2)
1.94
)
triclinic
ꢀ
P1, 2
7.9918(2)
10.5354(2)
8.0486(2)
110.531(1)
86.187(3)
91.416(2)
633.21(2)
2.05
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V, Å3
qcalc (g cmꢀ3
l
)
(Cu K
a
) (cmꢀ1
)
187
136
218
179
210
T (K)
298(2)
8–105
67.6
4851
298(2)
8–105
21.6
4851
298(2)
7–105
41.6
4901
298(2)
5–105
18
298(2)
5–105
15
2h range (°)
M/GOF
Ndata
5001
5001
Rp, Rw
RBragg
V/Z (Å3)
0.093, 0.125
0.084
335
0.086, 0.120
0.103
469
0.058, 0.077
0.043
316
0.053, 0.153
0.052
350
0.015, 0.095
0.038
328
(s, 4H, CH2Btm), 8.03 (s, 4H, CHBtm), 8.80 (s, 4H, CHBtm). Km (DMSO,
Strictly monophasic samples of 1, 4 and 5 were gently ground in
an agate mortar, and then deposited in the hollow of a 0.2 mm
deep aluminum sample holder, equipped with a quartz monocrys-
tal zero background plate (supplied by The Gem Dugout, State Col-
lege, PA). Diffraction data were collected in the 5–105° 2h range,
sampling at 0.02°, on a h:h vertical scan Bruker AXS D8 Advance
diffractometer, equipped with a linear Lynxeye position sensitive
293 °C): 24
l
S (1.0 ꢁ 10ꢀ3 M).
2.2.12. BtmSnnBu2(NO3)2 (11Btm
)
Bis(triazol-1-yl)methane (Btm) (0.150 g, 1.0 mmol) was added
to a dichloromethane solution (20 mL) containing nBu2Sn(NO3)2
(0.356 g, 1.0 mmol). A colorless precipitate formed which was fil-
tered off and washed with diethyl ether and shown to be com-
pound 11Btm (60% yield). M.p. 190 °C dec. Anal. Calc. for
detector, set at 300 mm from the sample. Ni-filtered Cu Ka1,2 radi-
ation, k = 1.5418 Å. Standard peak search methods, followed by
indexing by TOPAS-R [39], allowed the determination of approxi-
mate cell parameters; systematic absences allowed the detection
of the probable space groups (see Table 1), later confirmed by suc-
cessful structure solutions and refinements. Structure solution was
initiated by employing a semi-rigid molecular fragment for Btm,
flexible about two torsion angles (see Scheme 1), and free tin and
chloride atoms. Where pertinent, alkylic or aromatic residues were
added as further independent groups. Hydrogen atoms have been
positioned in idealized locations, as they have been included in
the definition of the rigid bodies. If the Btm molecule was found
to be bisected by a twofold axis, only a rigid portion of the mole-
cule was employed. Simulated annealing (occasionally helped by
soft restraints) allowed the location and orientation of the used
fragments, later refined by the Rietveld method. The fundamental
parameter approach in describing the peak shapes was employed,
the background contribution was modeled by a polynomial fit, and
preferred orientation effects for 4 (0 1 0 pole) were described by
the March–Dollase formulation [40]. A single isotropic thermal
parameter was adopted for the Sn atoms, while lighter atoms were
assigned B = BSn + 2.0 Å2. Fig. 1 shows the final Rietveld refinement
plots, with peak markers and difference plot at the bottom [41].
Structure solution and refinements were performed by TOPAS-R.
Crystal data, data collection parameters and agreement factors
are shown in Table 1. The indexed XRPD trace and the pertinent
Pawley fit for species 3 (in C2/c) is supplied in Fig. 2, where the
presence of a still unknown crystalline contaminant is evident.
C
13H23N8O6Sn, C, 30.85; H, 4.58; N, 22.14. Found: C, 30.77; H,
4.31; N, 22.34%. IR (KBr, cmꢀ1): 3139w, 3036w, 2964w; 2930w,
2864w; 1517m, 1484s, 1457m, 1382m, 1270s, 1200m, 1116s,
1032m, 996m, 981m, 959m, 884br, 812w, 781m, 728m, 687m,
670s. 1H NMR (CD3)2CO, 293 K): d, 0.83t, 1.31m, 1.6m, 1.88m
(18H, C4H9Sn), 6.44 (s, 4H, CH2Btm), 7.97 (s, 4H, CHBtm), 8.41 (s,
4H, CHBtm).
2.3. X-ray powder diffraction studies
Diffraction data of all powder specimens were measured at
room temperature, in air. Unfortunately, only a few (1, 4 and 5)
gave XRPD traces of decent quality, allowing a fruitful structural
determination (as reported hereafter), while the remaining ones,
even after different syntheses and preparations, did not afford
interpretable diffraction traces. Among these, we were able to de-
tect the lattice parameters of 3 and, perhaps, 6, but not to fully un-
ravel their crystal structure [38].
CH2
Bim
N
N
N
N
3. Results and discussion
CH2
τ1
N
τ2
N
3.1. Synthesis and spectroscopy
Btm
N
N
The reaction between diorganotin(IV) compounds R2SnX2 and
an equimolar quantities of Btm in organic solvent (ethanol,
methanol or dichloromethane) produces, in moderate yields, the
N
N
Scheme 1.

N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
3737
BtmSnMe2Cl2 100.00 %
800.000
700.000
600.000
500.000
400.000
300.000
200.000
100.000
0
-100.000
-200.000
-300.000
-400.000
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
180.000
160.000
140.000
120.000
100.000
80.000
60.000
40.000
20.000
0
BtmSnMe2Cl2 100.00 %
-20.000
-40.000
-60.000
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
(a)
450.000
400.000
350.000
300.000
250.000
200.000
150.000
100.000
50.000
0
BtmBPh2SnCl2 100.00 %
-50.000
-100.000
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
BtmBPh2SnCl2 100.00 %
120.000
100.000
80.000
60.000
40.000
20.000
0
-20.000
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
(b)
800.000
700.000
600.000
500.000
400.000
300.000
200.000
100.000
0
LixSnMeCl3 100.00 %
-100.000
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
240.000
220.000
200.000
180.000
160.000
140.000
120.000
100.000
80.000
60.000
40.000
20.000
0
LixSnMeCl3 100.00 %
-20.000
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
(c)
Fig. 1. Rietveld refinement plots for species 1Btm (a), 4Btm (b) and 5Btm (c) with difference plots and peak markers at the bottom. The lowest portions show the high-angle
range at a magnified scale (5ꢁ).

3738
N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
3.800
3.600
3.400
3.200
3.000
2.800
2.600
2.400
2.200
2.000
1.800
1.600
1.400
1.200
1.000
800
hkl_Phase 0.00 %
600
400
200
0
-200
-400
-600
-800
-1.000
-1.200
-1.400
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
Fig. 2. Pawley fit for species 3Btm, with difference plot and peak markers at the bottom. The presence of reflections from a yet unknown contaminant phase is obvious.
compounds Btm(R2SnX2) 1Btm–4Btm and 7Btm listed in Section 2.
The formation of these species requires long times and higher con-
centrations of the reactant, the products being moderately soluble
in the reaction solvents. The 2:1 adduct 10Btm (Btm)2(R2SnBr2)
formed in the same conditions also when the reaction was carried
agreement with the trend previously described for other analogous
complexes [48].
The 1H NMR spectra of derivatives 1Btm–4Btm and 7Btm in chlo-
roform, methanol or DMSO support the formulae proposed and
show that the organic ligand has not undergone any structural
change upon complexation. However, these spectra also show that
these polymeric complexes are completely dissociated in solution,
since only negligible differences exist between the chemical shifts
of the free ligand and those of the dissolved complexes. Further-
more, in the case of the trihalide and tetrahalide species, not solu-
ble in CHCl3, the spectra in DMSO or MeOH show sensible
dependence on the dilution: indeed, at low concentrations, very
close coincidence between the proton chemical shifts of the free li-
gand and of the dissolved complexes, is observed, whereas, at high-
er concentrations, the number of signals increases, suggesting the
occurrence of equilibria such as:
out in a strong excess of the organotin species. Derivatives 1Btm
,
3Btm, 4Btm and 10Btm were obtained upon addition of diethyl ether
to the reaction solution, whereas 2Btm and 7Btm formed upon slow
evaporation of the reaction solvent. The reaction between Btm and
RSnX3 or SnX4 immediately afforded colorless insoluble precipi-
tates of Btm(RSnX3) 5Btm–6Btm or Btm(SnX4) 8Btm–9Btm in high-
yield, independently on the solvent employed. No adduct has been
obtained by reacting, in the same reaction conditions, the donor
Btm with R3SnX, probably because of the +I effect of the organic
residues, diminishing the Lewis acidic character of the Sn(IV) cen-
ter. Finally the derivative 11Btm has been prepared only when Btm
was reacted with nBu2Sn(NO3)2, previously prepared. On the other
hand when Btm(R2SnX2) was reacted with AgX (X = NO3 or ClO4),
only untreatable materials or the starting reactants were recovered
from the reaction mixtures.
All obtained compounds, 1Btm–11Btm, are colorless solids, suffi-
ciently stable to air and soluble only in DMSO, acetone and some-
times also in CD3OD and CDCl3. The conductivity measurements in
DMSO and/or acetone suggest partial ionic dissociation into the
starting reagents for 1Btm–7Btm and 10Btm, whereas the tin adducts
8Btm and 9Btm behave in DMSO as 2:1 electrolytes.
\BtmðRSnX3Þ" þ xDMSO ¼ RSnX3ðDMSOÞx þ \Btm"
in which the elusive ‘‘Btm(RSnX3)” fragment is generated by
uncomplete disruption of the organometallic polymer or, vice versa,
by formation of oligomeric fragments based on the Btm–Sn(IV)
bond. The 119Sn NMR data, reported only for some selected com-
pounds, due to the low solubility of the species show that the di-
methyl and diethyltin(IV) chloride are comparable with that of
the corresponding Lewis acid in the same solvent and clearly indi-
cate that this type of complexes is extensively dissociated in solu-
tion [49]. On the other hand the 119Sn NMR spectra of the tri- and
tetrahalide tin complexes in CD3OD, acetone-d6 and DMSO-d6 [50]
indicates that this strong solvating species are able to displace the
Btm from the tin coordination sphere.
The IR data are also reported in Section 2. All the spectra show
very weak vibration bands at ca. 3000 cmꢀ1 that can be assigned to
the m(CH) of the heterocyclic ring, whereas a more intense absorp-
tion band at ca. 1600 cmꢀ1 is likely due to ring breathing [42]. Most
IR absorptions are slightly shifted with respect to the correspond-
ing absorptions in the free Btm. We have also compared the far-IR
spectra of the complexes 1Btm–4Btm, 7Btm and 10Btm with that of
the uncomplexed Btm, so that it has been possible to assign the
strong band found in 1Btm, falling near 575 cmꢀ1, to masym Sn–C
[43,44], whereas the two strong absorptions found in 4Btm at 291
and 282 cmꢀ1 suggest a markedly distorted trans-R2 distorted octa-
hedral diphenyltin(IV) complex [45,46]. In 3Btm and 4Btm, the Sn–C
stretching absorption bands are found at ca. 620 cmꢀ1. Upon com-
paring the low-lying Sn–Cl stretching frequencies in di-
3.2. Crystal chemistry
Crystals of 1Btm, 4Btm and 5Btm share the presence of one-
dimensional polymeric chains based on the Btm–Sn–Btm–Sn
sequence generated by exobidentate Btm ligands, which link dif-
ferently substituted organometallic Sn(IV) centers of pseudoocta-
hedral coordination geometry. Portions of the polymeric chain of
1Btm and 1Btm are shown in Figs. 3 and 4, respectively [51]. These
chains are invariably isooriented, and parallelly packed in all spe-
cies, no matter what crystal lattice and space group symmetry
are adopted by the overall 3D structure; however, the different
nature, size and geometry of the ancillary ligands modulate their
) )
(240 cmꢀ1), tri- (330–290 cmꢀ1 and tetrachloride (320 cmꢀ1
complexes with those of the starting tin(IV) and organotin(IV) spe-
cies [47], significant shifts to lower frequency are found, in full

N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
3739
Fig. 3. Schematic drawing of the polymeric chain present in compound 1Btm
.
Fig. 4. Schematic drawing of the polymeric chain present in compound 5Btm
.
Table 2
Synoptic collection of relevant structural and stereochemical features of the compounds 1Btm, 4Btm, 5Btm, 1Bim, 5Bim and Btm(Ph2SnBr2).
1Btm
4Btm
5Btm
1Bim
5Bim
Btm(Ph2SnBr2)
Ref.
This work
1D
This work
1D
This work
1D
octahedral
N2CCl3
trans-N,N
mer-Cl,Cl,Cl
[20]
1D
[20]
1D
octahedral
N2CCl3
trans-N,N
mer-Cl,Cl,Cl
[36]
1D
Topology
Geometry
Coordination
octahedral
N2C2Cl2
trans-N,N
trans-C,C
trans-Cl,Cl
2.237(2)
2.458(7)
2.15
octahedral
N2C2Cl2
cis-N,N
trans-C,C
cis-Cl,Cl
2.53-2.55
2.678(4)-2.692(3)
2.15
octahedral
N2C2Cl2
trans-N,N
trans-C,C
trans-Cl,Cl
2.31-2.32
2.43-2.45
2.12-2.20
11.09
octahedral
N2C2Br2
cis-N,N
trans-C,C
cis-Br,Br
2.45
2.62
2.15
9.57
88.2
Sn–N (Å)
Sn–Cl (Å)
Sn–C (Å)
Sn–Btm–Sn (Å)
N–Sn–N (°)
2.24(2)-2.33(2)
2.42-2.45
2.20
10.78
169.8(4)
C2
2.29
2.28, 2.49
2.29
10.64
173.4
C2
11.21
180
C2
9.85
100.8(4)
Cs
180
C2
Idealized Btm symmetry
Cs
Sn site symmetry
ꢀ1
1
1
ꢀ1
2
m
relative arrangement in the orthogonal plane, thus the 2D packing
of the polymeric chains. Another interesting versatility element is
the conformational flexibility about the two N–CH2 bonds, already
present in the Bim analogs, and, differently from these recently
published cases, the possibility of linkage isomerization, given that
Btm is a multitopic nitrogen ligand. In the following, a comparative
structural analysis is presented between Bim and Btm couples,
highlighting analogies, and, more fascinatingly, the most peculiar
differences, while the relevant stereochemical features of these
new species are synoptically collected in Table 2.
change of the nearly isosteric methyl and chloride residues) could
be easily ruled out from our XRPD analysis in 1Btm, thus clearly indi-
cating the trans N2C2Cl2 stereochemistry at the metal. The absence
of disorder is also partially reflected by the significantly lower mo-
lar volume of 1Btm, about 15 Å3 smaller than in 1Bim
.
ꢀ
At variance from 1Btm, Btm(MeSnCl3), 5Btm, is triclinic, P1, with
the metal atom lying in general position, as well as all other atoms
in the structure do. Also in this case the Btm ligand adopts a C2
conformation, as in 5Bim, but with markedly distinct lattice param-
eters, space group symmetry and site symmetry location of the
metal atom (bisected by a twofold axis in 5Bim). Slightly different
bridged Snꢂ ꢂ ꢂSn interactions (10.64 and 10.78 Å, in 5Bim and 5Btm
,
3.2.1. Crystal structures of 1Btm and 5Btm
respectively) in these non-isomorphous species are observed, both
significantly lower than those present in the dimethyl derivatives
1Bim and 1Btm, discussed above. Also in the case of 5Btm, no disorder
was observed among the methyl and chlorine ligands. Additionally,
also in this case, a slightly denser phase is observed, with a ca.
These two compounds, Btm(Me2SnCl2) and Btm(MeSnCl3), are
expected to be isostructural, thanks to the substantial similarity
of the isosteric methyl and chlorine ligands. While this is nearly
true in terms of molecular geometry and overall chain conforma-
tion, their crystal packing is substantially different.
Indeed, Btm(Me2SnCl2) crystallizes in the C2/c space group, with
the metal atom lying in the ꢀ1 special position and the Btm ligand
bisected by a twofold axis. This implies that the Btm ligand adopts
the nearly ubiquitous [for Sn(IV) polymers] C2 conformation, as in
1Bim, even if the lattice parameters speak for a non-isomorphous
character of the two derivatives. This difference can be traced back
to the different lengths of the bridged Snꢂ ꢂ ꢂSn interactions (11.09
and 11.21 Å, in 1Bim and 1Btm, respectively) and, particularly, to
the (approximate) [0 0 1] and [1 0 2] orientation of the chains in
the two (nearly isooriented) monoclinic lattices. Interestingly, the
disorder affecting the crystal structure of 1Bim (the mutual inter-
10 Å3 smaller molar volume than 5Bim
.
3.2.2. Crystal structure of 4Btm
Species Btm(Ph2SnCl2), 4Btm, crystallizes in the monoclinic
space group P21/n with all atoms lying in general position. Also
in this case, a 1D polymeric chain is present (see Fig. 5), built by
pseudooctahedral SnC2N2Cl2 centers (with a rare trans C–C, cis-
N,N and cis-Cl,Cl stereochemistry) which, connected through the
Btm bridges, lie approximately 9.45 Å apart. As in the already
known bromine analog, Btm(Ph2SnBr2) [36], the two phenyl rings,
attached to the same Sn(IV) atoms, show a staggered conformation.

3740
N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
Fig. 5. Schematic drawing of the polymeric chain present in compound 4Btm
.
Despite of this similarity, and of the common Cs symmetry of the
Btm ligand in the two Btm(Ph2SnX2) (X = Cl, Br) species, the two
crystals adopt different crystal systems, but are related by a proper
group-subgroup relation, the bromine derivative possessing higher
symmetry (Pnma vs. P21/n11, once reorientation of the cell axes is
allowed), with the two phenyls bisected (in different ways!) by one
mirror plane. As expected, also the Snꢂ ꢂ ꢂSn are similar [9.57 Å in
Btm(Ph2SnBr2)], and reflect the larger size of the halide in the latter
species.
Acknowledgements
We thank the Italian MIUR for funding (PRIN06: Materiali ibridi
con proprietà funzionali). We thank Simona Galli (University of
Insubria) for helpful discussions.
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4. Conclusions
The present paper reports on the preparation and characteriza-
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the rarely studied bis-(1,2,4-triazolyl) ligand. Of the several materi-
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powder diffraction data, and allowed the retrieval of a coherent
structural model. However, even in these fortunate cases, the qual-
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with those of other Btm or Bim derivatives, highlighting the non-
isomorphous character of the selected couples.
Why for the Btm derivatives the (well defined) analytical data
do not match with equally good powder diffraction traces (which,
in some cases, contain unindexable peaks, or show very poor crys-
tallinity) is not yet understood. We tentatively put forward the
hypothesis that, in the solid, linkage-isomers of the Btm ligand
(possessing different donor sites) may exist, disrupting the ideal
crystalline periodicity. Perhaps, only solid-state NMR may help in
assigning such variability, which solution (multinuclear) NMR
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only low-mass (monomeric?) complexes exist, thus limiting the
power of the spectroscopic information derived therefrom.
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CCDC 767916, 767917 and 767918 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.

N. Masciocchi et al. / Inorganica Chimica Acta 363 (2010) 3733–3741
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ꢀ
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C13H24Cl2N6Sn,
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V = 1925 Å3, = 1.57 g cmꢀ3
q
. A
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