Synthesis and supramolecular architectures of tetrakis(triorganostannyltetrazoles), including the crystal structure of hydrated 1,2,4,5-tetrakis(triethylstannyltetrazolyl)benzene

Article abstract of DOI:10.1039/a901737b

Six tetrakis(triorganostannyltetrazolyl)-alkanes and -benzenes have been prepared by a cycloaddition reaction between SnR₃N₃ and either 1,2,4,5-(NC)₄C₆H₂, 1,1,3,3-(NC)₄C₃H₄ or 1,3,3,5-(NC)₄C₅H₈. All compounds contain tin in a trans-XYSnR₃ environment; in anhydrous compounds the axial co-ordination about tin is exclusively from the tetrazoles (X, Y = N), while hydrated materials may also contain less symmetrical arrangements (X = N; Y = O). The structure of 1,2,4,5-tetrakis(triethylstannyltetrazolyl)benzene dihydrate has been determined and displays a complex three-dimensional network in which each tetrazole acts as at least a bidentate unit. One molecule of water co-ordinates one of the metal centres while the other is embedded in the lattice as a guest.

Full text of DOI:10.1039/a901737b

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Synthesis and supramolecular architectures of tetrakis(triorgano-
stannyltetrazoles), including the crystal structure of hydrated
1,2,4,5-tetrakis(triethylstannyltetrazolyl)benzene
Sonali Bhandari, Mary F. Mahon and Kieran C. Molloy*
Department of Chemistry, University of Bath, Claverton Down, Bath, UK BA2 7AY.
E-mail: chskcm@bath.ac.uk
Received 4th March 1999, Accepted 26th April 1999
Six tetrakis(triorganostannyltetrazolyl)-alkanes and -benzenes have been prepared by a cycloaddition reaction
between SnR3N3 and either 1,2,4,5-(NC)4C6H2, 1,1,3,3-(NC)4C3H4 or 1,3,3,5-(NC)4C5H8. All compounds contain
tin in a trans-XYSnR3 environment; in anhydrous compounds the axial co-ordination about tin is exclusively from
the tetrazoles (X, Y = N), while hydrated materials may also contain less symmetrical arrangements (X = N; Y = O).
The structure of 1,2,4,5-tetrakis(triethylstannyltetrazolyl)benzene dihydrate has been determined and displays a
complex three-dimensional network in which each tetrazole acts as at least a bidentate unit. One molecule of water
co-ordinates one of the metal centres while the other is embedded in the lattice as a guest.
the methanolic solutions gave gummy materials for 1, 3–6,
which needed trituration with hexane to give the respective
products in a powder form. Compound 2 crystallised from
methanol as a dihydrate in a form suitable for X-ray
Introduction
We have been investigating the structural chemistry of organo-
tin tetrazoles, influenced primarily by the variety of supra-
molecular lattices which these species generate.1–5 In such
crystallography.
compounds the metal centre invariably adopts a trans-N2SnC3
geometry with a near-linear N–Sn–N moiety (established both
crystallographically and by Mössbauer spectroscopy) thus act-
ing as a rigid connector between multifunctional azoles. The
Spectroscopy
1
The H and 13C NMR data for compounds 1–6 are largely
unexceptional but confirm the formulations shown in Scheme 1.
The 13C NMR spectra of all species clearly show the quaternary
carbon of the tetrazole at δ ca. 160 confirming the result of the
cycloaddition reaction; 1J(Sn–C) ≈ 480 Hz fall within the range
for five-co-ordinate tin and the semiempirical relationship
derived by Holecek and Lycka6 for correlating 1J and C–Sn–C
angles in butyltin compounds suggests a value of 124Њ for
compounds 1, 3 and 5, implying a trans-trigonal bipyramidal
geometry about the metal centre.
polydentate nature of each tetrazole leads to a wide variety of
supramolecular structures, the nature of which appears to be
dependent on the hydrocarbon groups bonded to the tin. Thus,
while 1,2-(Et3SnN4C)2C6H4 adopts a non-planar layer struc-
ture, its n-butyl analogue, 1,2-(Bu3SnN4C)2C6H4, exhibits a
three-dimensional architecture with pores filled by the hydro-
carbon groups.4 Other arrangements we have identified include
a two-dimensional network of hexamers [1,3,5-(Bu3SnN4C)3-
C6H3, 1,3,5-(Bu3SnN4CCH2CH2)3CNO2]5 and a bilayer struc-
ture with channels running in all three directions.3 The latter
arises when a flexible alkyl chain is used to link two organotin
tetrazoles [1,6-(Bu3SnN4C)(CH2)6].
As the number of organometallic tetrazoles inherent in the
molecular motif increases so, potentially, does the complexity
of the lattice construct. We now report the syntheses of
tetrakis(triorganostannyltetrazolyl)-alkanes and -benzenes as a
natural extension of our earlier work on systems containing
two and three organostannyl tetrazole moieties. The structure
of 1,2,4,5-(Et3SnN4C)4C6H2ؒ2H2O is presented and is the most
complex yet of this family of compounds.
The 119Sn NMR spectra of compounds 1–6 exhibit reson-
ances between δ Ϫ40 and Ϫ80. In comparison with previous
work on organotin-substituted tetrazoles this indicates a five-
co-ordinate tin.2 For example, the 119Sn chemical shifts of 1,2-
[(R3Sn)N4C]C6H4 (R = Et, Bun or Pri), 1,3-[(R3Sn)N4C]C6H4
(R = Et or Bun) and 1,4-[(R3Sn)N4C]C6H4 (R = Bun or Pri) fall
within the range of δ Ϫ40 to Ϫ83 and are to low frequency of
four-co-ordinated SnBu3(NMe2) (δ 36).7 The five-co-ordination
at tin could be achieved either via co-ordination of a solvent
molecule (as for previously reported triorganostannyl tetra-
zoles, highly co-ordinating d6-DMSO was required for dis-
solution of NMR samples) or via formation of an oligomeric
species. There is, however, no structural precedent for DMSO
co-ordination in the solid state. In addition, the linewidths of
the 119Sn resonances are broad (half width at half height,
HWHH, ca. 470 Hz). Simple R3SnN4CRЈ species exhibit
similar spectral characteristics as a result of migration of the tin
around the tetrazole nitrogens.2
Results and discussion
Synthesis
Six triorganotin-substituted tetra-tetrazoles 1–6 have been syn-
thesized using the well established [3ϩ2] cycloaddition route,2
in which a tetranitrile is heated with a slight excess of the
appropriate azide under nitrogen in the absence of any solvent
(Scheme 1). Reactions usually reached completion at elevated
temperatures (100–170 ЊC) over one hour. The course of the
reaction was followed by the disappearance of the IR bands due
to the ν(N3) at ≈2060 cmϪ1 and ν(CN) at ≈2250 cmϪ1. The crude
products in all cases were recrystallised from methanol. Cooling
The Mössbauer spectra for compounds 1–6 have isomer
shifts (i.s.) in the range 1.30–1.55 mm sϪ1 and quadrupole split-
ting (q.s.) between 3.5 and 3.9 mm sϪ1. The former confirms the
ϩ4 oxidation state of the tin atom while the latter points towards
a trans-trigonal bipyramidal geometry around tin, consistent
with the NMR analysis. For comparison, q.s. values of 1,2-
[(R3Sn)N4C]C6H4 (R = Et, Bun or Pri), 1,3-[(R3Sn)N4C]C6H4
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Scheme 1
(R = Et or Bun) and 1,4-[(R3Sn)NC4]C6H4 (R = Bun or Pri) fall
within the narrow range of 3.60–3.86 mm sϪ1 4
The trans-
ethyl groups. The asymmetric unit contains four trans-N2SnC3
[Sn(1)–Sn(4)] centres and one trans-NOSnC3 centre [Sn(5)].
Both these trigonal bipyramidal tin environments have been
found in previously examined tin tetrazoles and are consistent
with the spectroscopic interpretation (see above). The axially
ligating atoms for the five tins, the N–Sn–N/N–Sn–O bond
angles and the modes of co-ordination of the tetrazole ring
with respect to the tins are summarised in Table 1. The seven
unique Sn–N bond lengths are essentially equivalent within
experimental error and the strength of N–Sn bonding is
reflected in the proximity of all the N–Sn–N to 180Њ. The co-
ordination between tetrazole and tin can be described with
respect to the metal atom as being either N1 (see Scheme 1 for
numbering; for tin, N1, N4 are equivalent) or N2 (N2, N3 are
similarly equivalent). The versatility of the tetrazole co-
ordination is reflected in the occurrence of both N1 ϩ N2
[Sn(2), Sn(4)] and N2 ϩ N2 [Sn(1), Sn(3)] environments. The
N1 ϩ N2 co-ordination mode has been noted previously in 1,2-
(Bu3SnN4C)2C6H4 while the N2 ϩ N2 mode has been found in
1,2-(Et3SnN4C)2C6H4.4
The gross three-dimensional structure of compound 2 (Fig.
2) is complex but can be broadly described in terms of layers.
Propagation along c takes place primarily through the trans-
N2Sn(3) [Sn(3) in the asymmetric unit as presented sits on an
inversion centre at 0, 0.5, 0], while propagation along a takes
place via trans-N2Sn(2) and trans-N2Sn(4). In addition, the
lattice is extended in the b direction through the influence of the
ligands, which are of two distinct types. The ligand based on
C(1) (type A) has an inversion centre at the middle of the C6
ring (0.25, 0.75, 1.0) and is oriented asymmetrically with respect
to b. The ligand based on C(7) (type B) has a twofold rotation
axis through C(7) and C(10) parallel to b (0, y, 0.25) and is thus
symmetrically disposed with respect to this axis. Both ligand
types, but particularly those of type A, orchestrate lattice
propagation into a third dimension.
.
trigonal bipyramidal geometry about tin is achieved by axial
co-ordination of the tetrazoles, a feature which is common in
all published organotin tetrazole structures. Possible exceptions
to this may occur, however, in the case of hydrated 2, 4 and 6. In
these three cases, both trans-N2SnC3 and trans-NOSnC3 co-
ordinations are possible, the latter arising if the intermolecular
N→Sn is replaced by H2O→Sn, and both are consistent with
the Mössbauer data. The quadrupole splittings for both possi-
bilities (N2SnC3 vs. NOSnC3) fall within the same range, e.g. q.s.
for crystallographically characterised 1,3-bis(tributylstannyl-
tetrazolyl)benzene bis(methanol) is 3.65 mm sϪ1.4 A precedent
for simultaneous observation of both tin environments in the
same lattice exists in bis(trimethylstannyl)-5,5Ј-azotetrazole
for which similar Mössbauer data have also been recorded
(q.s. = 3.90 mm sϪ1).8 Broad linewidths for 5 (Γ = 0.98, 1.07)
and 6 (0.83, 1.05 mm sϪ1) are possibly caused by the asymmetry
inherent in the tetratetrazole ligands, which in turn may give
rise to a combination of different co-ordination modes between
tin and the tetrazole nitrogens, e.g. N1 ϩ N2, N1 ϩ N3, N1 ϩ N4,
etc. (see numbering in Scheme 1).
Crystallography
The asymmetric unit of compound 2 consists of three tins of
unit occupancy [Sn(2), Sn(4), Sn(5)], two tins which coincide
with inversion centres of half occupancy [Sn(1), Sn(3)], along
with two separate ligand halves (Fig. 1). Selected bond lengths
and bond angles are given in Table 1. The crystallographic
symmetry at the two metal centres [Sn(1), Sn(3)] gives rise to
disorder with respect to the attached ethyl groups such that only
2 of 6 β-carbons in these groups could be located with any
certainty and refined. The overall structural analysis is in no
way compromised by these difficulties.
All tin environments are trigonal bipyramidal with equatorial
The pseudo-five-sided, 28-atom rings visible in Fig. 2 contain
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Fig. 1 The asymmetric unit of compound 2, showing the labelling scheme used in the text and Tables. Ellipsoids are at the 30% probability level.
This effectively anchors the position of the two tetrazoles based
on C(4) [via the nitrogens not co-ordinating Sn(1)] and gener-
ates a new 26-membered centrosymmetric macrocycle (Fig. 3;
highlighted in green but sharing some common atoms with the
28-membered ring shown in orange). Finally, the lattice can
alsobeviewedasaninterpenetratingnetwork. Thepseudo-eight-
sided rings comprising of 38 atoms, built from 6 trans-N2Sn
units and fragments of two type A and four type B ligands (Fig.
3, blue), have the trans-N2Sn(1) bridge (generated by the inver-
sion centre at 0.25, 0.25, 1.0) involving ligand type A threaded
through them.
The hydrogen-bonding interactions discussed above result
from an interaction between the water molecule [O(1)] co-
ordinated to Sn(5) and N(3) of the lattice neighbour generated
by the operation 1 Ϫ x, 1 Ϫ y, 2 Ϫ z [O(1)–N(3): 2.65(2) Å]. The
distance Sn(5)–O(1) [2.27(1) Å] of compound 2 is comparable
to Sn–O of hydrated 1,4-(Bu3SnN4C)2C6H4ؒH2O [2.368(6) Å].9
There is also a second water molecule [O(2)], not co-ordinated
to tin but occupying an interstitial guest site within the lattice,
which is hydrogen bonded to both O(1) and N(5) of the sym-
metry related molecule generated by the 0.5 Ϫ x, Ϫ0.5 ϩ y, z
transformation [O(2) ؒ ؒ ؒ O(1) 2.72(2); O(2) ؒ ؒ ؒ N(5) 2.84(2) Å].
This is the first example of a non-metal bound solvent guest
in an organotin tetrazole lattice and suggests other inclusion
species can be synthesized more rationally.
Finally, the hierarchy for nitrogen co-ordination within the
tetrazole is evident in the behaviour of the four independent
heterocycles within the asymmetric unit (Fig. 1). Tetrazoles
based on C(6) and C(11) exhibit N1 ϩ N3 co-ordination (Table
1; see Scheme 1 for numbering), this being the least sterically
demanding combination and the one we have most commonly
observed in other organotin tetrazole structures. The tetrazole
incorporating C(4) also adopts N1 ϩ N3 co-ordination, with tin
bound to N3 (the primary binding site) and the weaker hydro-
gen bond relegated to the use of N1. The tridentate tetrazole
involving C(5) follows a similar pattern: primary co-ordination
to tin using N1 ϩ N3, followed by the use of N4 for the hydrogen
bonds. In summary, N1 ϩ N3 co-ordination imposes the least
three tin atoms [Sn(2)–Sn(4)] and lie approximately in the ac
plane. However, these rings are not planar and are tilted with
respect to the b axis. They can be viewed as starting and finish-
ing at tetrazoles based on C(5) sharing a common phenylene
bridge (type A) and are highlighted in orange in Fig. 3. The
tetrazoles labelled 1 or 2 on either side of the type A tetra-
tetrazole are oriented approximately 30Њ with respect to the
ac-plane and facilitate the “top to bottom” nature of these rings
in the superstructure.
The formation of the three-dimensional lattice is, however,
complex as several features contribute to the propagation along
b. First, there are two distinct types of ligands as described
above. Secondly, the spirals associated with Sn(2) and Sn(4), the
pseudo four-sided rings (Fig. 2), are not planar but are related
by the screw axis at 0.25, y, 0.25 which propagates the lattice
along b. Thirdly, there is a hydrogen-bonding interaction
involving water [O(1)] which is co-ordinated to Sn(5) and N(3).
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Fig. 2 The unit cell of compound 2 viewed along b. Colour code: Sn, blue; C, black; N, orange, O, green. Ethyl groups omitted for clarity.
steric clash between bulky metal centres, and is the primary
mode of tetrazole co-ordination. The use of N1 involves steric
clashes with the hydrocarbon group attached to the adjacent
carbon but these are less significant than metal–metal inter-
actions which would arise from N2 ϩ N3 bonding. Hydrogen
bonds are subservient to tin co-ordination and involve N1, then
N4, for their formation.
Experimental
Spectra were recorded on the following instruments: JEOL
GX270 (1H, 13C NMR), GX400 (119Sn NMR), Perkin-Elmer
599B (IR). Details of our Mössbauer spectrometer and related
procedures are given elsewhere.10 Isomer shift data are relative
to CaSnO3. For all compounds, infrared spectra were recorded
as Nujol mulls on KBr plates and all NMR data were recorded
on saturated solutions in DMSO-d6.
Conclusion
Syntheses
Polyfunctional tetrazoles incorporating four organotin tetra-
zole units can be synthesized and used to construct complex
three-dimensional supramolecular lattice arrangements. The
structure of 1,2,4,5-(Et3SnN4C)4C6H2ؒ2H2O has been deter-
mined as an example and emphasises the structural versatility
of tetrazoles in orchestrating supramolecular architectures. The
utility of polytetrazoles in the development of such structures
is, however, limited by the increasing lack of solubility which
accrues as more tetrazoles are incorporated into the ligands.
The tributyltin and triethyltin azides were prepared by the
literature methods.11 The method of Belsky12 was used to pre-
pare 1,3,3,5-pentanetetracarbonitrile.12 All other reagents were
of commercial origin (e.g. Aldrich) and used without further
purification.
CAUTION: owing to their potentially explosive nature, all
preparations of and subsequent reactions with organotin azides
were conducted under an inert atmosphere behind a rigid safety
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Table 1 Selected structural data for compound 2a
Tin
Tetrazole
Tin
Sn–N/Å
N–Sn–N/Њ
co-ordinationa
Tetrazole
co-ordinationb
1
2
Sn(1)–N(1) 2.36(1)
Sn(2)–N(8) 2.43(1)
Sn(2)–N(9) 2.37(1)
Sn(3)–N(13) 2.40(1)
Sn(4)–N(6) 2.42(1)
Sn(4)–N(15) 2.39(1)
Sn(5)–N(11) 2.42(1)
Sn(5)–O(1) 2.27(1)
N(1)–Sn(1)–N(1Ј)
N(9)–Sn(2)–N(8)
180
176.3(4)
N2 ϩ N2
N1 ϩ N2
C(4)
C(5)
N1 ϩ N3 c
N1 ϩ N2 ϩ N4 c
3
4
N(13)–Sn(3)–N(13Ј) 180
N(6)–Sn(4)–N(15)
N2 ϩ N2
N1 ϩ N2
C(6)
C(11)
N1 ϩ N3
N1 ϩ N3
179.2(4)
5d
N(11)–Sn(5)–O(1)
175.6(5)
N1
a See Scheme 1 for numbering; with respect to tin, N1, N4 and N2, N3 are equivalent pairs. b See Scheme 1 for numbering. c Atom N1 involved in
hydrogen bonding. d Tin co-ordinated to N, O.
Fig. 3 A stereoscopic view of the unit cell of compound 2 highlighting the formation of 28- (orange), 26- (green) and 38-atom (blue) rings. Ethyl
groups omitted for clarity.
screen. None of the tetrazoles synthesized showed any tend-
ancy to detonate at temperatures up to their melting points (ca.
200 ЊC).
1,2,4,5-Tetrakis(triethylstannyltetrazolyl)benzene dihydrate 2.
A mixture of triethyltin azide (0.92 g, 3.71 mmol) and
1,2,4,5-tetracyanobenzene (0.15 g, 0.84 mmol) was heated
under N2 at 105 ЊC for 30 min. The reaction mixture formed a
white solid at this temperature, which was washed with hexanes
and dried in vacuo. The resultant white powder, which was par-
tially soluble in methanol, was extracted in this solvent using
a Soxhlet apparatus. Hot filtration afforded a clear solution,
which on cooling at room temperature produced colourless
crystals (0.59 g, 56%), mp 200 ЊC [Found (Calc. for C17H33-
N8OSn2): C, 33.5 (33.9); H, 5.32 (5.53); N, 17.8 (18.6)%]. NMR
Syntheses
1,2,4,5-Tetrakis(tributylstannyltetrazolyl)benzene 1. A mix-
ture of tributyltin azide (2.89 g, 8.7 mmol) and 1,2,4,5-
tetracyanobenzene (0.39 g, 2.12 mmol) was heated under N2 at
120 ЊC for 45 min. The reaction mixture formed a white solid
at this temperature, which was then dissolved in hot methanol.
Hot filtration afforded a green solution, which on cooling pro-
duced a green gum, which was then washed with hexanes to give
1 as a green powder (0.99 g, 30%), mp 210 ЊC (decomp.) [Found
(Calc. for C29H55N8Sn2): C, 46.2 (47.2); H, 7.30 (7.20); N, 14.9
1
[(CD3)2SO]: H, δ 8.0 (s, 2 H, H3,6 of C6H2), 0.8–1.4 (m, 60
H, CH2CH3); 13C, δ 160.2 (CN4), 131.1 (C3,6 of C6H2), 129.3
(C1,2,4,5 of C6H2), 9.7 (CH2CH3), 9.1 (CH2CH3), 1J[13C–117,119Sn]
478 (unresolved), 2J[13C–117,119Sn] 34.9 Hz (unresolved); 119Sn, δ
Ϫ43.2. 119mSn Mössbauer (mm sϪ1): i.s. = 1.50; q.s. = 3.76. IR
(cmϪ1, KBr disk ): 3661, 3061, 2924, 2870, 1637, 1479, 1460,
1427, 1377, 1190, 1074, 1057, 1022, 997, 729, 698, 661, 524 and
447.
1
(15.1)%]. NMR [(CD3)2SO]: H, δ 8.49 (s, 1 H, H3 of C6H2),
8.10 (s, 1 H, H6 of C6H2), 1.45 (m, 24 H, SnCH2CH2CH2CH3),
1.20–1.30 (m, 48 H, SnCH2CH2CH2CH3) and 0.77 [m, 36 H,
(CH2)3CH3]; 13C, δ 159.9 (CN4), 134.2 (C3,6 of C6H2), 117.7
(C1,2,4,5 of C6H2), 27.7 (SnCH2CH2CH2CH3), 26.5 [Sn(CH2)2-
CH2CH3], 18.4 [SnCH2(CH2)2CH3], 13.5 [(CH2)3CH3],
2J[13CH2–117,119Sn] 77.2 (unresolved), 3J[13CH2–117,119Sn] 28.6 Hz
(unresolved); 119Sn, δ Ϫ48.6. 119mSn Mössbauer (mm sϪ1):
i.s. = 1.50; q.s. = 3.67. IR (cmϪ1, KBr disk ): 3406, 2957, 2924,
2872, 2856, 1658, 1618, 1464, 1417, 1377, 1358, 1292, 1217,
1157, 1080, 1047, 1026, 879, 769, 700, 679, 524 and 432.
1,1,3,3-Tetrakis(tributylstannyltetrazolyl)propane 3. A mix-
ture of tributyltin azide (2.07 g, 6.23 mmol) and 1,1,3,3-
tetrapropanecarbonitrile (0.18 g, 1.30 mmol) was heated while
stirring under N2 at 130 ЊC for half an hour. An orange-brown
glass was formed at this temperature, which was dissolved in
J. Chem. Soc., Dalton Trans., 1999, 1951–1956
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hot methanol. Hot filtration resulted in a yellow solution,
which, on cooling, gave a yellow gummy substance. The yellow
gum, when washed with hexanes, gave compound 3 as a yellow
perature. A crystal of approximate dimensions 0.25 × 0.25 ×
0.3 mm was used for data collection.
Crystal data. C34H66N16O2Sn4, M = 1205.79, monoclinic,
a = 30.070(3), b = 14.241(2), c = 25.259(2) Å, β = 105.28(1)Њ,
powder (0.43 g, 24%), mp 195 ЊC [Found (Calc. for C55H112
-
N16Sn4): C, 44.8 (44.0); H, 7.61 (7.58); N, 15.2 (14.9)%]. NMR
[(CD3)2SO]: 1H, δ 1.48 (m, 24 H, SnCH2CH2CH2CH3), 1.2–1.3
(m, 48 H, SnCH2CH2CH2CH3) and 0.78 [m, 36 H, (CH2)3CH3];
13C, δ 163.0 (CN4), 27.7 (SnCH2CH2CH2CH3), 26.4 [Sn(CH2)2-
U = 10434(2) Å3, space group C2/c, Z = 8, Dc = 1.535 g cmϪ3
,
µ(Mo-Kα) = 1.936 mmϪ1, F(000) = 4784.
Crystallographic measurements were made at 293(2) K on a
CAD4 automatic four-circle diffractometer in the range
2.17 < θ < 23.92Њ. Data (8368 reflections) were corrected for
Lorentz-polarisation effects and also for linear decay of the
crystal during data collection. In the final least squares cycles
all Sn, O and N atoms along with carbons 1–11 were allowed to
vibrate anisotropically. Ethyl carbons were refined isotropically
as a consequence of disorder of these groups which naturally
arises from the site symmetry of the associated centres [Sn(1)
and Sn(3)]. Associated α-carbons were refined with half site
occupancies but only two β-carbons could be reliably located
and refined around these two metal centres. Hydrogen atoms
were included at calculated positions where relevant on non-
disordered ethyl groups. The hydrogen atoms on the water
molecules could not be located with any reliability and were
not modelled. The solution of the structure (SHELXS 86)13
and refinement (SHELXL 93)14 converged to a conventional
[i.e. based on 4244 reflections with Fo > 4σ(Fo)] R1 = 0.0628
and wR2 = 0.1451. Goodness of fit = 1.043. The maximum and
minimum residual densities were 0.944 and Ϫ1.086 e ÅϪ3
respectively.
2
CH2CH3], 18.1 [SnCH2(CH2)2CH3], 13.5 [(CH2)3CH3], J[13C–
117,119Sn] 76 Hz (unresolved); 119Sn, δ Ϫ50.2. 119mSn Mössbauer
(mm sϪ1): i.s. = 1.47; q.s. = 3.65. IR (cmϪ1, KBr disk): 3420,
2957, 2924, 2872, 2855, 2073, 1653, 1635, 1464, 1377, 1342,
1292, 1155, 1126, 1026, 960, 879, 679 and 611.
1,1,3,3-Tetrakis(triethylstannyltetrazolyl)propane dihydrate 4.
Prepared as for compound 3 using triethyltin azide (1.83 g,
7.38 mmol) and 1,1,3,3-tetrapropanecarbonitrile (0.26 g, 1.81
mmol). Yellow powder (1.75 g, 80%), mp 205 ЊC (decomp.)
[Found (Calc. for C31H68N16O2Sn4): C, 31.8 (31.8); H, 5.68
1
(5.86); N, 19.0 (19.1)%]. NMR [(CD3)2SO]: H, δ 1.0–1.3 (m,
60 H, CH2CH3); 13C, δ 163.5 (CN4), 10.1 (CH2CH3), 10.0
(CH2CH3), 1J[13C–117,119Sn] 478 Hz (unresolved); 119Sn, δ Ϫ45.1.
119mSn Mössbauer (mm sϪ1): i.s. = 1.53; q.s. = 3.87. IR (cmϪ1
,
KBr disk): 3406, 3182, 2949, 2870, 2735, 1458, 1421, 1379,
1199, 1126, 1016, 956 and 684.
1,3,3,5-Tetrakis(tributylstannyltetrazolyl)pentane 5. Pre-
pared as for compound 3 using tributyltin azide (2.13 g, 6.42
mmol) and 1,3,3,5-tetracyanopentane (0.26 g, 1.5 mmol). Yel-
low powder (1.56 g, 70%), mp 209 ЊC [Found (Calc. for
C57H116N16Sn4): C, 45.6 (44.1); H, 7.73 (7.46); N, 14.9 (14.7)%].
NMR [(CD3)2SO]: 1H, δ 2.50–2.80 [m, 4 H, C(CH2CH2)2], 1.48
(m, 24 H, SnCH2CH2CH2CH3), 1.20–1.25 (m, 48 H, SnCH2-
CH2CH2CH3) and 0.76 [m, 36H, (CH2)3CH3]; 13C, δ 160.0
(CN4), 27.7 (SnCH2CH2CH2CH3), 26.4 [Sn(CH2)2CH2CH3],
18.1 [SnCH2(CH2)2CH3], 13.5 [(CH2)3CH3], 1J[13C–117,119Sn] 476
(unresolved), 2J[13C–117,119Sn] 75.4 Hz (unresolved); 119Sn,
δ Ϫ53.5. 119mSn Mössbauer (mm sϪ1): i.s. = 1.47; q.s. = 3.59. IR
(cmϪ1, KBr disk): 3387, 2957, 2924, 2872, 2856, 1655, 1589,
1464, 1400, 1377, 1342, 1292, 1251, 1226, 1080, 1049, 1026, 962,
879, 771, 748, 679, 611, 515 and 453.
CCDC reference number 186/1442.
See http://www.rsc.org/suppdata/dt/1999/1951/ for crystallo-
graphic files in .cif format.
Acknowledgements
We thank the University of Bath for financial support in the
form of a studentship (to S. B.).
References
1 R. J. Deeth, K. C. Molloy, M. F. Mahon and S. Whitaker,
J. Organomet. Chem., 1992, 430, 25.
2 S. J. Blunden, M. F. Mahon, K. C. Molloy and P. C. Waterfield,
J. Chem. Soc., Dalton Trans., 1994, 2135.
1,3,3,5-Tetrakis(triethylstannyltetrazolyl)pentane hydrate 6.
Prepared as for compound 3 using triethyltin azide (1.72 g, 6.9
mmol) and 1,3,3,5-tetracyanopentane (0.25 g, 1.5 mmol). Yel-
low powder (1.17 g, 68%), mp 206 ЊC (decomp.) [Found (Calc.
for C33H68N16Sn4ؒH2O): C, 33.3 (33.5); H, 5.78 (5.92); N, 19.0
(18.9)%]. NMR [(CD3)2SO]: 1H, δ 1.04–1.50 (m, 60 H,
CH2CH3) and 2.48–2.55 [m, 4 H, C(CH2CH2)2]; 13C, δ 161.5
(CN4), 121.9 [(CN4)2C], 38.2 [(CN4)2C(CH2)2(CH2)2], 21.9
[(CN4)2C(CH2)2(CH2)2], 10.9 [CH2CH3], 10.8 (CH2CH3),
1J[13C–117,119Sn] 482 Hz (unresolved); 119Sn, δ Ϫ51.8. 119mSn
Mössbauer (mm sϪ1): i.s. = 1.43; q.s. = 3.63. IR (cmϪ1, KBr
disk): 2949, 2850, 1637, 1458, 1400, 1196, 1130, 1016, 962 and
682.
3 A. Goodger, M. Hill, M. F. Mahon, J. G. McGinley and K. C.
Molloy, J. Chem. Soc., Dalton Trans., 1996, 847.
4 M. Hill, M. F. Mahon, J. G. McGinley and K. C. Molloy, J. Chem.
Soc., Dalton Trans., 1996, 835.
5 M. Hill, M. F. Mahon and K. C. Molloy, J. Chem. Soc., Dalton
Trans., 1996, 1857.
6 J. Holecek and A. Lycka, Inorg. Chim. Acta, 1986, 118, L15.
7 B. Wrackmeyer, Annu. Rep. NMR Spectrosc., 1985, 16, 73.
8 M. F. Mahon, K. C. Molloy and S. F. Sayers, unpublished results.
9 S. Bhandari, Ph.D. Thesis, University of Bath, 1998.
10 K. C. Molloy, T. G. Purcell, K. Quill and I. Nowell, J. Organomet.
Chem., 1984, 267, 237.
11 W. T. Reichle, Inorg. Chem., 1964, 3, 237.
12 I. Belsky, J. Chem. Soc., Chem. Commun., 1977, 237.
13 G. M. Sheldrick, SHELXS 86, A Computer Program for Crystal
Structure Determination, University of Göttingen, 1986.
14 G. M. Sheldrick, SHELXL 93, A Computer Program for Crystal
Structure Refinement, University of Göttingen, 1993.
X-Ray crystallography
Suitable crystals of 1,2,4,5-tetrakis(triethylstannyltetrazolyl)-
benzene dihydrate 2 were grown from methanol at room tem-
Paper 9/01737B
1956
J. Chem. Soc., Dalton Trans., 1999, 1951–1956