Zinc thiosemicarbazide dicarboxylates: The influence of the anion shape on supramolecular structure

Article abstract of DOI:10.1016/S0277-5387(02)01399-2

The syntheses and crystal structures of the zinc thiosemicarbazide dicarboxylate compounds [Zn(tsc)₂(OH₂)₂][fumarate] 2, [Zn(tsc)₂(citraconate)]·H₂O 3, [Zn(tsc)(μ-1,4-phenylenediacetate)] 4, [Zn(Ettsc

Full text of DOI:10.1016/S0277-5387(02)01399-2

Polyhedron 22 (2003) 673ꢀ686
/
www.elsevier.com/locate/poly
Zinc thiosemicarbazide dicarboxylates: the influence of the anion
shape on supramolecular structure
Jennifer E.V. Babb, Andrew D. Burrows *, Ross W. Harrington, Mary F. Mahon
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
Received 8 July 2002; accepted 14 August 2002
Abstract
The syntheses and crystal structures of the zinc thiosemicarbazide dicarboxylate compounds [Zn(tsc)2(OH2)2][fumarate] 2,
[Zn(tsc)2(citraconate)]×H2O 3, [Zn(tsc)(m-1,4-phenylenediacetate)] 4, [Zn(Ettsc)2(citraconate)]×3H2O 5, [Zn(Ettsc)2(Hphthalate)]-
[Hphthalate]×H2O 6, [Zn(Metsc)2(Hphthalate)][Hphthalate]×H2O 7, [Zn(Me2tsc)2(OH2)][terephthalate]×2H2O 8 and [Zn(EtMe2ts-
/
/
/
/
/
c)2(OH2)][terephthalate] 9 are reported. The supramolecular structures of the terephthalate and fumarate compounds 2, 8 and 9
consist of chains of cations and anions, in which the ions are linked by hydrogen bonding. In contrast, compounds 3, 5, 6 and 7
contain carboxylate groups co-ordinated to the metal centre to give either neutral or monocationic species. These differences can be
rationalised on the basis of the dicarboxylate structure, in particular the angle between the carboxylate vectors. Compound 4 forms
co-ordination polymers in an analogous manner to thiourea derivatives.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Hydrogen bonding; Crystal engineering; Zinc; Carboxylates; X-ray crystal structures
1. Introduction
We have previously shown that the interactions
between bis(thiosemicarbazide)nickel [5,6] orꢀzinc [7]
/
Crystal engineering is the name often given to the
branch of supramolecular chemistry concerned with the
planning and utilisation of crystal-orientated syntheses
and the evaluation of the physical and chemical properties
of the resultant crystalline materials [1]. Although
routine prediction of crystal structures remains a distant
goal, progress in this field has arisen through the
identification and use of ‘supramolecular synthons’,
cations and dicarboxylate anions can lead to the
formation of one-dimensional chains in which the
cations and anions are linked by charge-augmented
hydrogen bonds involving DD:AA motifs (Dꢁ
/
hydro-
gen bond donor, Aꢁhydrogen bond acceptor) in which
/
the secondary interactions are all attractive. For exam-
ple, the metathesis reaction between [Zn(tsc)2](NO3)2
[tscꢁ
/
thiosemicarbazide] and sodium terephthalate gives
2H2O 1, part of the
[Zn(tsc)2(OH2)2][terephthalate]×
/
[2]*small units that are anticipated to interact together
/
structure of which is shown in Fig. 1. In this paper, we
investigate the effects of changing the thiosemicarbazide
and the dicarboxylate on the products of this reaction.
Substitution of those hydrogen atoms not involved in
chain formation by alkyl groups has been shown to
affect the presence of the DD:AA interaction in nickel
complexes, and the manner in which the chains are
linked when they are observed [6]. Variation of the
dicarboxylate influences both the relative orientation of,
and the distance between the two carboxylate groups.
The thiosemicarbazide ligands and dicarboxylates used
in this paper are shown in Fig. 2.
strongly, and thus dictate the intermolecular interac-
tions between molecules or ions. Many of these ‘supra-
molecular synthons’ involve multiple hydrogen bonds,
and rely on the strength and directionality of these
interactions [3]. The geometric preferences of transition
metal centres can be exploited to orient hydrogen
bonding groups in pre-ordained directions [4].
* Corresponding author. Tel.: ꢂ
826231.
E-mail address: a.d.burrows@bath.ac.uk (A.D. Burrows).
/
44-1225-386529; fax: ꢂ44-1225-
/
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0277-5387(02)01399-2

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J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
Fig. 1. The supramolecular structure of [Zn(tsc)2(OH2)2][terephthalate]×2H2O 1.
/
and [Zn(EtMe2tsc)2(OH2)][terephthalate] 9 were pre-
pared from the reaction of either [Zn(Me2tsc)2](NO3)2
or [Zn(EtMe2tsc)2](NO3)2 with sodium terephthalate in
aqueous solution. In all cases, slow evaporation of the
water led to the formation of colourless crystals which
were analysed by single-crystal X-ray crystallography.
The compounds were isolated in 61ꢀ73% yield as the
/
only observed metal-containing products, and a combi-
nation of microanalysis and unit cell determinations
confirmed that the crystals chosen for the structural
determinations were representative of the bulk materi-
als. Poor solubility of the compounds prevented satis-
1
factory H NMR spectra from being obtained. Selected
bond lengths and angles for compounds 2ꢀ9 are given in
/
Table 1.
2.1. [Zn(tsc)2(OH2)2][fumarate] (2)
In the crystal structure of 2, the asymmetric unit
consists of half a [Zn(tsc)2(OH2)2]2ꢂ cation and half a
fumarate anion, with the remainder of the ions gener-
ated through inversion centres located on the half-
occupancy zinc atom and at the centre of the fumarate.
The cation has distorted octahedral geometry with two
mutually trans tsc ligands and two axial aqua ligands.
The cations and anions are linked via DD:AA interac-
Fig. 2. Thiosemicarbazide and dicarboxylate structures.
2. Synthesis and characterisation of the zinc
thiosemicarbazide dicarboxylate compounds 2
tions [graph set R22(8)] [8] between the parallel NÃ
/H
/
9
ꢀ
H2O 3 and [Zn(tsc)(m-1,4-pheny-
groups of the tsc ligands and the oxygen atoms of the
carboxylate groups of the fumarate to form one-dimen-
sional chains, in the same manner as was previously
observed in the terephthalate compound 1 [7]. The
hydrogen-bonded chains in 2 are linked into two-
The compounds [Zn(tsc)2(OH2)2][fumarate] 2,
[Zn(tsc)2(citraconate)]×
/
lenediacetate)] 4 were prepared by reaction of
[Zn(tsc)2](NO3)2 with the relevant sodium dicarboxylate
in aqueous solution. The compounds [Zn(Ettsc)2-
dimensional sheets via NÃ
/
H
/
Á Á Á
/
O hydrogen bonds be-
(citraconate)]×
[Hphthalate]×H2O
[Hphthalate]×H2O 7 were prepared by reaction of
/
3H2O
5,
[Zn(Ettsc)2(Hphthalate)]-
tween the thioamido NÃH group [N(3)Ã
/
/H(3B)] and a
/
6 and [Zn(Metsc)2(Hphthalate)]-
carboxylate oxygen atom O(2), (Fig. 3(a)). These inter-
actions result in the formation of R44(18) and R42(18)
rings, all of approximately equal dimensions. This is in
contrast to 1, in which linking of the hydrogen bonded
chains into sheets led to both small [R24(18)] and large
/
[Zn(Metsc)2](NO3)2 or [Zn(Ettsc)2](NO3)2 with sodium
citraconate or phthalate in aqueous solution. The
compounds [Zn(Me2tsc)2(OH2)][terephthalate]×
/2H2O 8

J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
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686
675
Table 1
Selected bond lengths (A) and angles (8) for compounds 2ꢀ
˚
/9
2a
3b
5b
6c
7d
8e
9a
4
Zn(1)Ã
Zn(1)Ã
Zn(1)Ã
Zn(1)Ã
Zn(1)Ã
/
S(1)
S(2)
N(a)
N(b)
O
2.4494(6) 2.3640(8)
2.4220(8)
2.3681(9)
2.4438(10)
2.159(3)
2.137(3)
2.005(2)
2.3961(7) 2.4129(7) 2.3137(8) 2.3102(14)
2.3795(7) 2.3738(7) 2.3247(8)
Zn(1)Ã
Zn(1)Ã
Zn(1)Ã
Zn(1)Ã
Zn(2)Ã
Zn(2)Ã
Zn(2)Ã
Zn(2)Ã
/
S(1)
2.283(3)
2.135(8)
1.968(6)
1.937(7)
2.298(3)
2.143(8)
1.984(7)
1.939(6)
/
/
N(1)
O(1)
O(3)’
S(2)
/
2.167(2)
2.142(2)
81.26(5)
2.159(2)
2.150(2)
2.0185(17)
2.122(2)
2.177(2)
2.082(2)
2.114(2)
2.215(2)
2.049(2)
2.271(2)
2.260(2)
2.004(1)
2.2776(19)
1.968(2)
82.30(6)
/
/
/
/
/
/
N(4)
O(5)
O(7)
N(a)Ã
/
Zn(1)Ã
Zn(1)Ã
/
S(1)
S(2)
82.53(6)
82.70(6)
82.83(7)
81.24(8)
83.55(5)
81.19(6)
83.09(5)
80.88(5)
82.08(5)
82.55(5)
/
N(b)Ã
/
/
/
N(1)Ã
/
Zn(1)Ã
/
S(1)
S(2)
86.5(2)
85.9(2)
N(4)Ã
/
Zn(2)Ã
/
a
b
c
N(a)Ä
N(a)Ä
N(a)Ä
/
N(1), OÄ
N(3), N(b)Ä
N(3), N(b)Ä
N(3), N(b)Ä
N(3), N(b)Ä
/
O(3).
N(6), OÄ
N(6), OÄ
N(6), OÄ
N(6), OÄ
/
/
/
O(1).
/
/
/
O(2).
d
e
N(a)Ä
/
/
/
O(5).
O(1W).
N(a)Ä
/
/
/
R44(32) rings. This difference in the structures of 1 and 2
is concurrent with a disparity in the manner in which the
sheets are linked together to form the gross structure. In
the fumarate compound 2 the sheets are linked into the
and AA sites on the same molecule ensures that these
chains are directional. However, neighbouring chains
are orientated in opposite directions, so overall the
crystal is non-polar. The chains are linked together by a
three-dimensional structure via an NÃ
and two OÃ Á Á ÁO hydrogen bonds in which the aqua
ligands provide the hydrogen bond donors (Fig. 3(b)) in
addition to a weaker NÃ S interaction [N(1) S(1)
3.520(2) A]. This contrasts with the structure of 1, in
which an included water molecule acts as a ‘linker’
between the sheets. These water molecules project into
neighbouring sheets, and serve to fill the large rings in 1.
/
H
/
Á Á Á
/
O interaction
combination of NÃ
/
H
/
Á Á Á
/
O hydrogen bonds and addi-
/
H
/
/
tional hydrogen bonds in which the included water
provides either donor or acceptor sites [N(1)
/
Á Á Á
/
O(1W)
˚
/
H
/
Á Á Á
/
/
Á Á Á
/
3.033(4), H(1A)
1488; N(3) O(2) 2.872(3), H(3A)
Á Á Á
H(3A) O(2) 1748; N(4)Á Á ÁO(1W) 2.970(4), H(4A)
Á Á Á
O(1W) 2.13 A, N(4)ÃH(4A)Á Á ÁO(1W) 1628; N(5)Á Á Á
O(3) 2.856(3), H(5) O(3) 2.00 A, N(5)Ã O(3)
Á Á Á
1638; N(6) O(4) 3.214(3), H(6B)Á Á ÁO(4) 2.35 A, N(6)Ã
Á Á Á
H(6B) O(4) 1748; O(1W)Á Á ÁO(3) 2.811(3), H(1WA)Á Á Á
Á Á Á
O(3) 1.96 A, O(1W)ÃH(1WA)Á Á ÁO(3) 1658; and O(1W)
Á Á ÁO(1) 3.107(3), H(1WB)Á Á ÁO(1) 2.28 A, O(1W)Ã
H(1WB) O(1) 1628]. Surprisingly, one of the NH
Á Á Á
groups [N(4)ÃH(4B)] is not involved in a hydrogen
/
Á Á Á
/
O(1W) 2.27 A, N(1)Ã
/
H(1A)Á Á Á
/
/O(1W)
˚
˚
/
/
/
Á Á Á
/
O(2) 2.00 A, N(3)Ã
/
/
/
/
/
/
Á Á Á
/
˚
/
/
/
/
/
˚
/
/
/
H(5)
/
Á Á Á
/
˚
/
/
/
/
/
/
/
/
/
/
/
˚
2.2. [Zn(tsc)2(citraconate)]×
/
H2O (3)
/
/
/
/
˚
/
/
/
/
In the crystal structure of compound 3, the asym-
metric unit consists of a discrete, neutral [Zn(tsc)2(ci-
traconate)] molecule, formed via k1-co-ordination of the
dicarboxylate to the zinc centre, and an included water
molecule. The zinc centres have distorted trigonal
bipyramidal geometry, as evidenced by the structural
index parameter t [9] which is 0.67, with the axial
positions occupied by a sulfur atom from one tsc ligand
and a nitrogen atom from the other. An intramolecular
hydrogen bond to an oxygen atom on the non-co-
/
/
/
bond, being directed into the cleft between citraconate
and tsc ligands.
2.3. [Zn(tsc)(m-1,4-phenylenediacetate)] (4)
The asymmetric unit of compound 4 consists of two
fragments, one of which contains a Zn(tsc) moiety k1-
co-ordinated to a 1,4-phenylenediacetate, the other a
Zn(tsc) moiety k1-co-ordinated to two halves of 1,4-
phenylenediacetate anions. The presence of crystallo-
graphic inversion centres ensure that independent co-
ordination polymers are generated from each of the
fragments, one of which is shown in Fig. 5(a). Although
this represents the only observation of co-ordination
polymerisation including a Zn(tsc)2ꢂ centre, co-ordina-
tion polymers of the type [Zn(tu)2(m-dicarboxylate)]
ordinated carboxylate group [N(3)Ã
/
H(3B)
/
Á Á Á
/
O(4)]
serves to lock the citraconate conformation [graph set
S(9)].
Co-ordination of the dicarboxylate to the [Zn(tsc)2]2ꢂ
centre prevents formation of cation
/
Á Á Á
/
anion
/
Á Á Á
/
cation
chains in the same manner as observed in 1 and 2.
However, [Zn(tsc)2(citraconate)] contains both DD and
AA hydrogen bonding sites, the latter from the unco-
ordinated carboxylate group, and a DD:AA interaction
is observed between these groups to form zigzag
hydrogen bonded chains (Fig. 4). Inclusion of the DD
(tuꢁ
/
thiourea) are the most common product from the
reaction of [Zn(tu)4]2ꢂ with dicarboxylates [10].

676
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
/
686
˚
Fig. 3. Hydrogen bonding in compound 2. (a) Formation of sheets. The hydrogen bond distances (A) and angles (8) are N(2)
/
Á Á Á
O(2) 2.939(3), H(3B)
O(2) 3.236(3), H(1B) O(2) 2.41, N(1)Ã
Á Á Á
O(1) 2.723(2), H(4B) O(1) 1.90, O(3)ÃH(4B)Á Á Á
Á Á Á
/
O(2) 2.788(3), H(2)
/
Á Á Á
/
O(2) 1.95, N(2)Ã
N(3)ÃH(3B)Á Á ÁO(2) 149. (b) Linking of sheets. The hydrogen bond distances (A) and angles (8) are N(1)
H(1B) O(2) 154; O(3)Á Á ÁO(1) 2.768(2), H(4A)Á Á ÁO(1) 1.95, O(3)ÃH(4A)Á Á ÁO(1) 172; and O(3)Á Á Á
Á Á Á
O(1) 173.
/
H(2)
/
Á Á Á
/
O(2) 169; N(3)
/
Á Á Á
/
O(1) 2.831(3), H(3A)
/
Á Á Á
/
O(1) 2.00, N(3)Ã
/
H(3A)
/
Á Á Á
/
O(1) 175; and N(3)
/
Á Á Á
/
/
Á Á ÁO(2) 2.22,
/
˚
/
/
/
/
Á Á Á
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
˚
The co-ordination polymers based on Zn(1) and Zn(2)
O hydrogen bonds, with the
principal hydrogen bonding motif involving the parallel
H(5)
O(4) 2.93(1), H(6A)
1448]. Zn(1)- and Zn(2)-based polymers become prox-
/
Á Á Á
/
O(4) 2.00 A, N(5)Ã
/
H(5)
/
Á Á Á
/
O(4) 1498; and N(6)
/
Á Á Á
/
˚
are linked by NÃ
/
H
/
Á Á Á
/
/
Á Á ÁO(4) 2.18 A, N(6)Ã
/
/
H(6A)
/
Á Á Á
/
O(4)
˚
˚
NH groups hydrogen bonding to a single non-co-
ordinated carboxylate oxygen atom, with graph set
˚
imate (Zn
/
Á Á Á
/
Zn 4.4 A) at intervals of 20.8 A, and interact
at these points through two pairs of NÃ
/
H
/
Á Á Á
/
O hydrogen
R12(6) [N(2)
/
Á Á Á
/
O(8) 2.85(1), H(2)/
Á Á Á
/
O(8) 2.07 A, N(2)Ã
/
bonds in which the co-ordinated carboxylate oxygen
atoms act as hydrogen bond acceptors forming R22(6)
motifs. (Fig. 5(b)).
H(2)
/
Á Á Á
/
O(8) 1508; N(3)
/
Á Á Á
/
O(8) 2.84(1), H(3A)/
Á Á Á
/
O(8)
˚
2.06 A, N(3)Ã
/
H(3A)/
Á Á Á
/
O(8) 1508; N(5)
/
Á Á ÁO(4) 2.77(1),
/

J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
/
686
677
˚
Fig. 4. Hydrogen bonding in compound 3, linking the molecules into chains. The hydrogen bond distances (A) and angles (8) are N(1)
2.875(3), H(1B) O(4) 2.02, N(1)ÃH(1B)Á Á ÁO(4) 162; N(2)Á Á ÁO(3) 2.782(3), H(2)Á Á ÁO(3) 1.91, N(2)ÃH(2)Á Á ÁO(3) 176; N(6)Á Á Á
Á Á Á
O(2) 2.01, N(6)ÃH(6A)Á Á ÁO(2) 164; and N(3)Á Á ÁO(4) 2.881(3), H(3B)Á Á ÁO(4) 2.06, N(3)ÃH(3B)Á Á ÁO(4) 154.
/
Á Á Á
/
O(4)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
O(2) 2.868(3), H(6A)
/
Á Á Á
/
/
/
/
/
/
/
/
/
/
/
2.4. [Zn(Ettsc)2(citraconate)]×
/
3H2O (5)
H groups is hydrogen-bonded to a carboxylate oxygen
atom, while the other is hydrogen-bonded to a water
molecule which is in turn hydrogen-bonded to the
carboxylate oxygen. The second set of parallel NH
The crystal structure of compound 5 consists of
molecules of [Zn(Ettsc)2(citraconate)], with three inde-
pendent molecules of water present per asymmetric unit.
The co-ordination geometry around the zinc centre can
groups [N(4)Ã
/
H(4) and N(5)Ã
/
H(5)] hydrogen bonds to
two carboxylate oxygen atoms on different citraconates,
which in turn are bridged by a water molecule giving a
be described as distorted square-pyramidal (tꢁ0.41),
/
R24(10) motif (Fig. 6(a)). NÃ
molecules into sheets, which are held together by
hydrogen bonds involving the included water molecules
in addition to an interaction between an Ettsc NH group
/
H
/
Á Á Á
/
O interactions link the
with two mutually cis thiosemicarbazide ligands occu-
pying the basal positions and a carboxylate group k1-co-
ordinated in the axial position. The conformation
adopted by the citraconate differs from that in com-
and a carboxylate oxygen atom [N(3)
˚
/
Á Á Á
/
O(4) 2.892(4),
pound 3: the C(8)ꢀ
/
C(7)ꢀ
/
O(1)ꢀZn(1) torsion angle in 5
/
H(3F)
/
Á Á Á
/
O(4) 2.03 A, N(3)Ã
/
H(3F)
/
Á Á ÁO(4) 1588] (Fig.
/
is 1468, demonstrating co-ordination of a syn lone pair,
whereas in contrast the equivalent torsion angle in 3 is
278, demonstrating co-ordination of an anti lone pair.
This change in co-ordination mode leads to a difference
in the orientation of the non-co-ordinated carboxylate
group, which in 5 lies essentially perpendicular to the
6(b)). Further hydrogen bonds involving the water
molecules serve to assemble the sheets into bilayers,
though there is no hydrogen bonding between these
bilayers.
two DD sets of NÃ
/
H bonds. In contrast to 3, there is no
2.5. [Zn(Rtsc)2(Hphthalate)][Hphthalate]×
/
H2O (Rꢁ
/
intramolecular hydrogen bonding in 5.
Et, 6; RꢁMe, 7)
/
DD:AA interactions between the Ettsc ligands and
carboxylates are absent in this structure. The non-co-
ordinated carboxylate does interact with two NH
groups, but each is located on a different molecule.
The structures of compounds 6 and 7 exhibit a
number of common structural features, and therefore
can be discussed together. Both asymmetric units consist
of a [Zn(Rtsc)2(Hphthalate)]ꢂ cation, a [Hphthalate]ꢃ
anion and an included water molecule. In compound 6
One of the sets of parallel NH groups [N(1)Ã
/
H(1) and
H(2)] forms a R23(8) motif, in which one of the NÃ
N(2)Ã
/
/

678
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
Fig. 5. (a) Part of one of the independent co-ordination polymers within the crystal structure of compound 4. (b) Hydrogen bonding linking the co-
˚
ordination polymers in compound 4. The hydrogen bond distances (A) and angles (8) are N(1)
131; N(1) O(5) 3.04(1), H(1B)Á Á ÁO(5) 2.20, N(1)ÃH(1B)Á Á ÁO(5) 154; N(4)Á Á ÁO(1) 2.96(1), H(4A)
Á Á Á
O(3) 3.08(1), H(4B) O(3) 2.39, N(4)ÃH(4B)Á Á ÁO(3) 134.
Á Á Á
/
Á Á Á
/
O(7) 3.02(1), H(1A)
/
Á Á Á
/
O(7) 2.35, N(1)Ã
/
H(1A)/
Á Á Á
/
O(7)
/
/
/
/
/
/
/
/
/
/
Á Á ÁO(1) 2.13, N(4)Ã
/
/
H(4A)/
Á Á ÁO(1) 151; and N(4)
/
/
Á Á Á
/
/
/
/
/
/
the geometry around the zinc centre is distorted trigonal
bipyramidal (tꢁ0.73) with a sulfur atom from one Rtsc
ligand and a nitrogen atom from the other in the axial
positions, and the remaining sulfur and nitrogen donors
together with a k1-co-ordinated carboxylate in the
equatorial positions. The geometry is similar in com-
pound 7, though the distortion towards a square
balance the charges. The hydrogen bonding patterns in
the two compounds are identical, and Fig. 7 depicts
compound 6 only.
As in 3, one of the NH groups from a co-ordinated
amino group forms an intramolecular hydrogen bond
[S(9)] to the non-co-ordinated carboxylic acid oxygen
atom, effectively locking the conformation of the
/
pyramidal geometry is greater in this case (tꢁ
/
0.41).
Hphthalate ligand [N(6)
/
Á Á Á
O(4) 1418]. One of the sets of
parallel NH groups [N(1)ÃH(1) and N(2)ÃH(2)] forms a
DD:AA interaction with the co-ordinated Hphthalate
/
O(4) 2.940(3), H(6B)
/
Á Á Á
/
O(4)
˚
Since in both 6 and 7, in contrast to 3 and 5, the non-co-
ordinated carboxylate group is protonated, an addi-
tional hydrogen phthalate anion is included in order to
2.21 A, N(6)Ã
/
H(6B)
/
Á Á Á
/
/
/

J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
/
686
679
˚
Fig. 6. Hydrogen bonding in compound 5. (a) Hydrogen bonds involving the sets of parallel NH groups. The hydrogen bond distances (A) and
angles (8) are N(1) O(7) 2.933(4), H(1)Á Á ÁO(7) 2.05, N(1)ÃH(1)Á Á ÁO(7) 178; N(2)Á Á ÁO(4) 2.849(4), H(2)Á Á ÁO(4) 2.05, N(2)ÃH(2)Á Á ÁO(4) 153; N(4)Á Á Á
Á Á Á
O(2) 2.873(4), H(4) O(2) 2.14, N(4)ÃH(4)Á Á ÁO(2) 139; N(5)Á Á ÁO(3) 2.812(4), H(5)Á Á ÁO(3) 1.97, N(5)ÃH(5)Á Á ÁO(3) 164; O(5)Á Á ÁO(3) 2.805(3), H(5WA)
Á Á Á
Á Á ÁO(3) 1.94, O(5)ÃH(5WA)Á Á ÁO(3) 162; O(5)Á Á ÁO(2) 2.811(3), H(5WB)Á Á ÁO(2) 1.96, O(5)ÃH(5WB)Á Á ÁO(2) 159; and O(7)Á Á ÁO(4) 2.713(4), H(7WB)Á Á Á
O(4) 1.85, O(7)ÃH(7WB)Á Á ÁO(4) 169. (b) Formation of sheets through hydrogen bonds involving the included water molecules.
/
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ligand on a neighbouring cation (Fig. 7(a)), with the co-
ordinated oxygen atom O(2) and carbonyl oxygen O(4)
of the carboxylic acid acting as acceptors [R22(11)]. This
motif is similar to that observed between the co-
ordination polymers in the structure of [Zn(tu)2(m-
phthalate)] [10] and serves to link the molecules into
chains. The other DD face [N(4)Ã
/
H(4) and N(5)Ã/H(5)]
interacts with oxygen atoms from a carboxylate [O(6)]

680
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
˚
Fig. 7. Hydrogen bonding in compound 6. (a) Formation of chains. Selected hydrogen bond distances (A) and angles (8) are N(1)
H(1) O(2) 1.93, N(1)ÃH(1)Á Á ÁO(2) 165; N(2)Á Á ÁO(4) 3.004(3), H(2)Á Á ÁO(4) 2.18, N(2)ÃH(2)Á Á ÁO(4) 158; N(4)Á Á ÁO(6) 2.950(3), H(4)
Á Á Á
N(4)ÃH(4)Á Á ÁO(6) 153; N(5)Á Á ÁO(9) 2.794(3), H(5)Á Á ÁO(9) 1.96, N(5)ÃH(5)Á Á ÁO(9) 159; N(3)Á Á ÁO(6) 2.863(3), H(3A)Á Á ÁO(6) 2.00, N(3)ÃH(3A)
163; and N(6) O(5) 2.957(3), H(6A)Á Á ÁO(5) 2.15, N(6)ÃH(6A)Á Á ÁO(5) 155. (b) Inclusion of water within channels. Selected hydrogen bond distances
Á Á Á
(A) and angles (8) are O(3) O(5) 2.538(2), H(3)Á Á ÁO(5) 1.60, O(3)ÃH(3)Á Á ÁO(5) 168; O(9)Á Á ÁO(5) 2.936(3), H(9B)Á Á ÁO(5) 2.15, O(9)ÃH(9B)Á Á ÁO(5)
Á Á Á
150; and O(9) O(6) 2.902(3), H(9A)Á Á ÁO(6) 2.29, O(9)ÃH(9A)Á Á ÁO(6) 127.
Á Á Á
/
Á Á Á
/
O(2) 2.792(3),
Á Á ÁO(6) 2.19,
Á Á ÁO(6)
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and the included water molecule [O(9)]. The two co-
ordinated NH2 groups can together also be regarded as
comprising two additional DD faces, with the faces
made up from one NH group from each of the amino
groups [11]. One of these ‘new’ faces [N(3)ÃH(3A) and
N(6)ÃH(6A)] forms a DD:AA interaction with the
/
/

J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
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686
681
carboxylate
group
of
the
non-co-ordinated
hydrogen bonding involving the water molecules.
Further OÃ Á Á ÁO interactions [O(2W)Á Á ÁO(2) 2.942(3),
H(2WA) H(2WA) O(2) 1678]
O(2) 2.06 A, O(2W)Ã
[Hphthalate]ꢃ anion (Fig. 7(a)).
/
H
/
/
/
/
˚
Further hydrogen bonding involves the included
water molecules, which reside in channels within the
structure (Fig. 7(b)). There is also p-stacking involving
both co-ordinated and non-co-ordinated [Hphthalate]ꢃ
anions.
/
Á Á Á
/
/
/
Á Á Á
/
serve to link these sheets into the three-dimensional
structure.
The hydrogen bonding pattern observed in this
structure is different from that observed in the nickel
analogue [Ni(Me2tsc)2(OH2)2][terephthalate]×
/2H2O [6].
In this compound the DD:AA interactions linking the
cations and anions are surprisingly absent, though all
potential hydrogen bond donors and acceptors are
utilised in hydrogen bonding. However, the nickel
complex has octahedral geometry, and the presence of
the second co-ordinated water appears to be sufficient to
change the hydrogen bonding pattern.
2.6. [Zn(Me2tsc)2(OH2)][terephthalate]×
/
2H2O (8)
In the crystal structure of 8, the asymmetric unit
consists of a [Zn(Me2tsc)2(OH2)]2ꢂ cation, a terephtha-
late anion and two included water molecules. In the
cation the metal geometry is distorted square pyramidal
(tꢁ0.20) with the two Me2tsc ligands orientated
/
mutually trans and the aqua ligand co-ordinated in the
axial position. The cations and anions are linked via
2.7. [Zn(EtMe2tsc)2(OH2)][terephthalate] (9)
In the crystal structure of compound 9 the asymmetric
DD:AA interactions between the two parallel NÃ
/
H
groups of the Me2tsc ligands and the oxygen atoms of
the carboxylate groups to form infinite chains (Fig. 8),
similar to those in 1. These chains are linked into pairs
unit
consists
of
a
discrete
5-co-ordinate
[Zn(EtMe2tsc)2(OH2)]2ꢂ cation and a terephthalate
anion, and unlike 8 there is no included solvent. The
co-ordination geometry of 9 is best described as
via NÃ
/
H
/
Á Á Á
/
O interactions to generate large [R44(32)] and
small [R24(8)] rings, again in a similar manner to 1.
However, these pairs are not directly hydrogen-bonded
to their neighbours, and sheet formation is mediated by
distorted trigonal bipyramidal (tꢁ0.65) with sulfur
/
and nitrogen atoms in the axial positions, and sulfur,
˚
Fig. 8. Formation of hydrogen-bonded sheets in compound 8. The hydrogen bond distances (A) and angles (8) are N(1)
/
Á Á Á
O(2) 2.758(2), H(2)
O(4) 2.831(2), H(4B) O(4) 2.02, N(4)Ã
Á Á Á
O(1) 2.652(2), H(1WA) O(1) 1.77, O(1W)ÃH(1WA)Á Á ÁO(1) 172;
Á Á Á
O(3W) 173; O(2W) O(3) 2.913(2), H(2WB). . .O(3) 2.02, O(2W)ÃH(2WB)Á Á Á
Á Á Á
H(3WA) O(3) 179; and O(3W)Á Á ÁO(2W) 2.863(3), H(3WB)Á Á ÁO(2W) 2.01, O(3W)Ã
Á Á Á
/
O(1) 2.838(2), H(1A)
Á Á ÁO(2) 1.87,
H(4B)
Á Á Á
/
Á Á Á
/
O(1) 1.95, N(1)Ã
N(2)ÃH(2)Á Á ÁO(2) 176; N(4)
O(4) 152; N(5) O(3) 2.816(2), H(5)
Á Á Á
O(1W) O(3W) 2.729(2), H(1WB)Á Á Á
Á Á Á
O(3) 172; O(3W) O(3) 2.864(2), H(3WA)
Á Á Á
H(3WB) O(2W) 167.
Á Á Á
/
H(1A)
/
Á Á Á
/
O(1) 176; N(1)
Á Á ÁO(4) 2.804(2), H(4A)
Á Á ÁO(3) 1.94, N(5)Ã
O(3W) 1.84, O(1W)Ã
Á Á ÁO(3) 1.98, O(3W)Ã
/
Á Á Á
/
O(3W) 3.106(3), H(1B)
Á Á ÁO(4) 1.94, N(4)Ã
H(5) O(3) 174; O(1W)
Á Á Á
H(1WB)
Á Á Á
/
Á Á Á
/
O(3W) 2.27, N(1)Ã
H(4A) O(4) 166; N(4)
Á Á Á
Á Á Á
/
H(1B)
/
Á Á Á
/
O(3W) 156; N(2)
/
Á Á Á
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Á Á Á
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682
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
nitrogen and co-ordinated water in the equatorial
positions. The difference in co-ordination geometry
between 8 and 9 does not affect the principal manner
in which the cations and anions interact: they are linked
into infinite chains via the same DD:AA motif observed
These differences in structure are not a consequence
of differences in co-ordination geometry. The series of
ionic compounds (1, 2, 8 and 9) includes 6-co-ordinate
octahedral and 5-co-ordinate structures that range from
square pyramidal to trigonal bipyramidal in the zinc
geometry. Similarly, the 5-co-ordinate compounds con-
taining co-ordinated dicarboxylate involve varying de-
grees of distortion. The energy surface between the two
extremes of square pyramidal and trigonal bipyramidal
is well established as being relatively flat [12], and
although difficult to quantify it is likely that the metal
geometry is sufficiently flexible to be able to facilitate
the most effective hydrogen bonding network.
in 1 and 8 involving the two NÃ
carboxylate oxygen atoms, (Fig. 9). These chains are in
turn linked into the three-dimensional structure via OÃ
O interactions involving the co-ordinated water and
/H groups and the
/
H
/
Á Á Á
/
a carboxylate oxygen atom.
The differences in structure observed in this series of
compounds are more readily rationalised on the basis of
the shape of the dicarboxylate, specifically the relative
orientation of the two carboxylate groups. Yaghi,
O’Keeffe and co-workers have recently described the
geometry of dicarboxylates in terms of three angles, u,
c and 8, and used these to help prepare porous metal-
organic frameworks with predictable structures [13].
Starting from the planar terephthalate anion, u repre-
sents bending in the centre of the anion with the two
carboxylates remaining co-planar, c represents bending
of the carboxylates towards each other, and 8 repre-
sents the relative twisting of the planes of the carbox-
ylate groups. These angles have been calculated from the
3. Discussion
Compounds 1ꢀ9 were all isolated in good yield as the
/
sole products from the seemingly straightforward reac-
tions between a bis(thiosemicarbazide)zinc(II) nitrate
and a sodium dicarboxylate. However, there is a
remarkable structural diversity in the products. Com-
pounds 1, 2, 8 and 9 form ionic compounds in which
DD:AA interactions serve to link the cations and anions
into hydrogen-bonded chains, compounds 3, 5, 6 and 7
form square pyramidal compounds in which a carbox-
ylate is co-ordinated to the zinc along with the two
thiosemicarbazide ligands, and compound 4 forms co-
ordination polymers.
˚
Fig. 9. Formation of the supramolecular structure in compound 9. The hydrogen bond distances (A) and angles (8) are N(2)
/
Á Á Á
/
O(3) 2.748(3), H(2)
/
Á Á Á
/
O(3) 1.88, N(2)Ã
/
H(2)
/
Á Á Á
/
O(3) 172; N(3)
/
Á Á Á
/
O(2) 2.792(3), H(3)
/
Á Á Á
/
O(2) 1.90, N(3)Ã
/
H(3)/
Á Á Á
/
O(2) 176; and O(1)
/
Á Á Á
/
O(2) 2.635(2), H(1A)
/
Á Á ÁO(2) 1.77, O(1)Ã
/
/
H(1A) (2) 169.
/
Á Á Á
/

J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ
/
686
683
˚
Table 2
Values for the angles u, c and 8 (8) for the dicarboxylates in the
carboxylates (5.3 A). Although this would not preclude
formation of hydrogen bonded chains in a compound
[Zn(tsc)2][1,4-phenylenediacetate] based on DD:AA in-
teractions, it is likely that the lateral displacement would
hamper the interactions between these chains to form
the three-dimensional structure. Although 4 represents
the only observation of a co-ordination polymer in this
series, these are the main products from the related
reaction of [Zn(tu)4]2ꢂ with dicarboxylates [10]. The
major factor governing the difference in the product
distributions from these reactions is the lower lability of
the bidentate tsc ligand with respect to the monodentate
thiourea ligand.
structures of compounds 1ꢀ9
/
Dicarboxylate
Terephthalate
Compound
u
c
8
1
8
9
180 172
180 180 30
0
180 180
0
Fumarate
1,4-Phenylenediacetate
2
180 180
180 180
0
0
4a
4a
171 177 39
Citraconate
Phthalate
3
5
69 180 89
69 177 81
6b
6c
7b
7c
59 164 56
63 177 84
63 163 52
64 178 89
The DD:AA interaction between two parallel NÃ
/
H
groups from a co-ordinated thiosemicarbazide ligand
and two oxygen atoms from a carboxylate [graph set
R22(8)] has been demonstrated to be a robust motif for
use in crystal engineering. In the nine structures
discussed in this paper, there are 18 carboxylate groups,
of which 11 (61%) are involved in this type of hydrogen
bonding. Of the seven which are not, six are prevented
from doing so by co-ordination, and only one forms
another hydrogen bonding motif. Hence 11 out of 12
non-co-ordinated carboxylate groups are involved in
a
One of the two independent chains.
Co-ordinated [Hphthalate]ꢃ
b
c
.
Non-co-ordinated [Hphthalate]ꢃ
.
crystal structures of 1ꢀ9, and are presented in Table 2.
/
For terephthalate and fumarate, u is 1808 as the
carboxylate groups are orientated in opposite directions;
their compounds consist of ionic structures held to-
gether by DD:AA interactions despite the presence of
various amounts of co-ordinated and non-co-ordinated
water molecules. These chains are flexible to changes in
c and 8, and for 8 the twist angle 8 is 308. For
DD:AA interactions*a ‘success rate’ of 92%, which
/
compares with the most robust hydrogen bonding
motifs known [16]. Moreover, this occurs despite the
presence of a competitive solvent, which is included in
the lattice either free or co-ordinated. Indeed, with the
rigid planar dicarboxylates terephthalate and fumarate,
only one compound has been structurally characterised
to date without cation
ions linked through these interactions [6]. The structures
in this paper support these observations, and show that
citraconate and phthalate u B908 and the compounds
/
contain co-ordinated carboxylates. With such acute
values of u, one of the carboxylate groups needs to
rotate in order to prevent steric repulsions between these
groups, and this is reflected in the much higher values of
8 observed in these compounds than for those of
terephthalate or fumarate. Co-ordination of the dicar-
boxylate may be driven by basicity, since the first pKa
for phthalic acid (2.94) is slightly lower than that for
terephthalic (3.54) or fumaric acid (3.02) [14]. However,
it is more likely that this is a ‘second choice’ arrange-
ment that is only observed when the more favourable
ionic-type structure is precluded on geometric grounds.
It is unclear why phthalate is protonated in the
structures of 6 and 7 whereas citraconate is not in the
structures of 3 and 5 as the second pKa for citraconic
acid is greater (6.17 vs. 5.43) [14,15]. It is noteworthy
that in both 6 and 7 the co-ordinated hydrogen
phthalate anion contains lower values of both c and
8 than the non-co-ordinated hydrogen phthalate.
/
Á Á Á
/
anion/
Á Á Á
/
cation chains with the
when u is acute these cation
/
Á Á Á
/
anion
/
Á Á Á
/
cation chains do
not form. Instead carboxylate co-ordination is observed
giving either neutral molecules or monocations, with the
non-co-ordinated carboxylates in these species generally
forming hydrogen bonds to parallel NH groups in tsc
ligands.
4. Experimental
4.1. General experimental
Microanalyses (C, H and N) were carried out by Mr
Alan Carver (University of Bath Microanalytical Ser-
vice). Infrared spectra were recorded on a Nicolet Nexus
FT-IR spectrometer as KBr pellets. Sodium dicarbox-
ylates were prepared by reaction of the appropriate
dicarboxylic acid with either sodium hydroxide or
sodium hydrogen carbonate where not available from
commercial sources. The compounds tsc, Metsc and
Ettsc were purchased from commercial sources. Me2tsc
The 1,4-phenylenediacetate compound 4 is unusual,
since the values for u, c and 8 for the dicarboxylate are
similar to those for terephthalate, whereas the observed
structure of 4 is very different to those of the terephtha-
late compounds 1, 8 and 9. The main structural
difference between these dicarboxylates is the large
lateral displacement of the CÃ/C bond vectors to the

684
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
and EtMe2tsc were synthesised using the literature
method [17].
IR (cmꢃ1): n(NH)/(OH) 3461s, 3307s (br), 2975s;
n(CO2)/d(NH) 1651s, 1557m.
4.7. Synthesis of
[Zn(Ettsc)2(Hphthalate)][Hphthalate]×
4.2. Synthesis of [Zn(tsc)2](NO3)2,
[Zn(Metsc)2](NO3)2, [Zn(Ettsc)2](NO3)2,
[Zn(Me2tsc)2](NO3)2, and [Zn(EtMe2tsc)2](NO3)2
/
H2O (6)
Yield 52 mg (70%). Found C, 40.6; H, 4.86; N, 12.5.
C22H32N6O9S2Zn requires C, 40.5; H, 4.64; N, 12.9%.
IR (cmꢃ1): n(NH)/(OH) 3396s, 3228s (br); n(CO2)/
d(NH) 1598s, 1457s (br).
Thiosemicarbazide, (0.200 g, 2.20 mmol), dissolved in
absolute ethanol (15 cm3), was added dropwise to an
absolute ethanolic solution of zinc(II) nitrate hexahy-
drate, (0.327 g, 1.1 mmol in 10 cm3), whilst stirring.
After approximately 10 min a white precipitate of
[Zn(tsc)2](NO3)2 was seen to form, and this was
collected by filtration. Yield 0.35 g (81%).
4.8. Synthesis of
[Zn(Metsc)2(Hphthalate)][Hphthalate]×
/
H2O (7)
Yield 45 mg (63%). Found C, 39.0; H, 4.11; N, 13.2.
C20H28N6O9S2Zn requires C, 38.5; H, 4.20; N, 13.5%.
IR (cmꢃ1): n(NH)/(OH) 3448s (br); n(CO2)/d(NH)
1604s (br), 1425s.
[Zn(Metsc)2](NO3)2, [Zn(Ettsc)2](NO3)2, [Zn(Me2-
tsc)2](NO3)2, and [Zn(EtMe2tsc)2](NO3)2, were synthe-
sised using analogous procedures, though a significant
reduction in the solvent volume was required before the
products crystallised in 70ꢀ85% yield.
/
4.9. Synthesis of [Zn(Me2tsc)2(OH2)][terephthalate]×
/
2H2O (8)
4.3. Synthesis of [Zn(tsc)2(OH2)2][fumarate] (2)
Yield 83 mg (73%). Found C, 31.7; H, 5.35; N, 15.8.
C14H28N6O7S2Zn requires C, 32.2; H, 5.37; N, 16.1%.
IR (cmꢃ1): n(NH)/(OH) 3275m; n(CO2)/d(NH) 1613s,
1533s, 1447s.
To an aqueous solution of [Zn(tsc)2](NO3)2 (100 mg,
0.27 mmol) was added an aqueous solution of sodium
fumarate, (43 mg, 0.27 mmol). After approximately 24 h
a colourless crystalline material, [Zn(tsc)2(OH2)2][fuma-
rate], was seen to form, which was separated by
filtration. Yield 73 mg (70%). Found C, 18.1; H, 3.98;
N, 21.0. C6H16N6O6S2Zn requires C, 18.1; H, 4.05; N,
21.1%. IR (cmꢃ1): n(NH)/(OH) 3514s, 3294s, 3000s
(br); n(CO2)/d(NH) 1638m, 1558s, 1438s.
4.10. Synthesis of
[Zn(EtMe2tsc)2(OH2)][terephthalate] (9)
Yield 89 mg (72%). Found C, 39.6; H, 5.91; N, 15.3.
C18H32N6O5S2Zn requires C, 39.9; H, 5.91; N, 15.5%.
IR (cmꢃ1): n(NH)/(OH) 3255s; n(CO2)/d(NH) 1604s,
1565s, 1358m.
Syntheses of compounds 3ꢀ9 were carried out using
/
the appropriate bis(thiosemicarbazide)zinc nitrate
(0.100 g) and one equivalent of the appropriate sodium
dicarboxylate in an analogous manner to that of
compound 2.
5. Crystallography
4.4. Synthesis of [Zn(tsc)2(citraconate)]×
/
H2O (3)
Single-crystals of compounds 2ꢀ
/
9 were prepared by
the methods above and analysed on either an Enrafꢀ
/
Yield 65 mg (61%). Found C, 21.3; H, 4.13; N, 21.3.
C7H16N6O5S2Zn requires C, 21.4; H, 4.09; N, 21.3%. IR
(cmꢃ1): n(NH)/(OH) 3381s, 3215s; n(CO2)/d(NH)
1604m, 1531s, 1444m.
Nonius CAD4 automatic four-circle diffractometer (2,
3, 8 and 9) or a Nonius Kappa CCD diffractometer (4,
5, 6 and 7) Table 3. The structures were solved using
SHELXS-97 and refined using SHELXL-97 [18]. Hydrogen
atoms were included at calculated positions on carbon
centres. All hydrogens attached to nitrogen and oxygen
atoms were located in the electron density maps and
refined at fixed distances from their parent atom.
4.5. Synthesis of [Zn(tsc)(m ꢀ1,4-phenyldiacetate)] (4)
/
Yield 67 mg (71%). Found C, 37.4; H, 3.84; N, 12.05.
C11H13N3O4SZn requires C, 37.9; H, 3.76; N, 12.0%. IR
(cmꢃ1): n(NH)/(OH) 3167w; n(CO2)/d(NH) 1570m,
1458s.
6. Supplementary material available
4.6. Synthesis of [Zn(Ettsc)2(citraconate)]×
/
3H2O (5)
Crystallographic data for compounds 2ꢀ
deposited with the Cambridge Crystallographic Data
Centre as supplementary publications CCDC 189017ꢀ
189024. Copies of the data can be obtained free of
/
9 have been
Yield 85 mg (65%). Found C, 27.1; H, 5.75; N, 17.3.
C11H28N6O7S2Zn requires C, 27.2; H, 5.77; N, 17.3%.
/

Table 3
Crystallographic parameters for compounds 2ꢀ
/9
Complex
2
3
4
5
6
7
8
9
Empirical formula
M
C6H16N6O6S2Zn
397.74
C7H16N6O5S2Zn
393.75
C22H26N6O8S2Zn2 C11H28N6O7S2Zn
695.33 485.88
C22H30N6O9S2Zn
652.01
C20H26N6O9S2Zn
623.96
C14H28N6O7S2Zn
521.91
C18H32N6O5S2Zn
541.99
Crystal size/mm
T(K)
˚
l(A)
0.20ꢄ
293(2)
0.71069
2.67ꢀ24.97
triclinic
/
0.20ꢄ
/
0.20 0.25ꢄ
293(2)
0.71069
2.59ꢀ24.97
/
0.20ꢄ
/
0.20 0.13ꢄ
293(2)
0.71070
3.08ꢀ24.20
/
0.13ꢄ/0.05
0.15ꢄ
296(2)
/
0.15ꢄ
/
0.10 0.30ꢄ
170(2)
0.71070
3.64ꢀ27.48
/
0.10ꢄ
/
0.10 0.25ꢄ
150(2)
0.71069
3.76ꢀ27.49
/
0.25ꢄ
/
0.25 0.25ꢄ
293(2)
0.71069
2.04ꢀ24.98
triclinic
/
0.20ꢄ
/
0.15 0.35ꢄ
293(2)
0.71069
2.36ꢀ24.96
/
0.30ꢄ0.30
/
0.71070
3.36ꢀ27.13
triclinic
u Range
/
/
/
/
/
/
/
/
Crystal system
Space group
monoclinic
P21/c
monoclinic
P21/n
monoclinic
P21/c
monoclinic
P21/c
monoclinic
C2/c
¯
¯
¯
P/
1
/
P/
1
/
P/ /
1
˚
a A
6.4053(7)
7.8436(8)
7.9661(9)
76.182(8)
78.570(10)
78.530(10)
376.07(7)
2
11.650(3)
7.6400(10)
17.590(3)
12.6541(10)
11.518(2)
18.705(3)
8.9190(6)
9.3860(7)
13.017(1)
90.099(3)
88.662(3)
81.684(4)
1077.9(2)
2
7.9700(1)
14.7810(2)
24.2320(4)
7.923(1)
14.370(2)
23.393(3)
9.344(2)
10.672(2)
12.753(2)
74.64(2)
76.87(2)
73.21(2)
1158.3(4)
2
22.490(12)
9.118(2)
15.819(8)
˚
b A
˚
c A
a 8
b 8
g 8
106.130(2)
99.516(10)
92.0270(9)
92.638(6)
129.74(3)
U
1504.0(5)
4
2688.8(7)
4
2852.85(7)
4
2660.6 (6)
4
2494.6(19)
4
Z
m (Mo Ka) (mmꢃ1
Reflections collected
Independent reflections
R(int)
)
1.945
1493
1.940
2873
2628
1.998
18774
4273
1.375
9661
1.066
48821
6525
1.140
46061
6101
1.286
4056
1.192
2301
2195
1322
0.0081
4654
0.0500
3411
0.0121
0.0146
0.1539
0.0513
0.0668
0.0125
R1, wR2 [I ꢀ
R indices (all data)
/
2s(I)]
0.0298, 0.0797
0.0306, 0.0824
0.0263, 0.0683
0.0433, 0.0741
0.0804, 0.1934
0.1151, 0.2176
0.0456, 0.0997
0.0731, 0.1118
0.0404, 0.0971
0.0575, 0.1058
0.0355, 0.0878
0.0550, 0.0992
0.0236, 0.0655
0.0318, 0.0686
0.0225, 0.0591
0.0313, 0.0618

686
J.E.V. Babb et al. / Polyhedron 22 (2003) 673ꢀ686
/
[6] M.T. Allen, A.D. Burrows, M.F. Mahon, J. Chem. Soc. Dalton
Trans. (1999) 215.
charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: ꢂ44-1223-336033, e-
/
[7] A.D. Burrows, S. Menzer, D.M.P. Mingos, A.J.P. White, D.J.
Williams, J. Chem. Soc. Dalton Trans. (1997) 4237.
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[10] A.D. Burrows, R.W. Harrington, M.F. Mahon, C.E. Price, J.
Chem. Soc. Dalton Trans. (2000) 3845.
Acknowledgements
The EPSRC is thanked for financial support.
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