Crystal structures of copper(II) complexes of 2-formylpyridine substituted thiosemicarbazones; the first example of a coordinated thiosemicarbazone with a thiol function

Article abstract of DOI:10.1016/S0022-2860(01)00471-9

The crystal structures of two 5-coordinate copper(II) complexes containing neutral, tridentate 2-formylpyridine N(4)-substituted thiosemicarbazones have been determined. 2-Formylpyridine N(4)-cyclohexylthiosemicarbazone, HFo4CHex coordinates via the pyridine nitrogen, imine nitrogen and thione sulfur with two chloro ligands to produce [Cu(HFo4CHex)Cl₂]. Similarly, 2-formylpyridine 3-(4-methylpiperazine)thiosemicarbazone, HFoppz4M, produces [Cu(HFoppz4M)Cl₂] with one major difference; rather than the expected thione form of the thiosemicarbazone moiety, it coordinates as the thiol isomer. Both complexes are close to a square pyramid structure with axial and equatorial chloro ligands and the thiosemicarbazone moieties of both ligands nearly planar. Also included is the crystal structure of N-cyclohexylthiosemicarbazide, CHextsc.

Full text of DOI:10.1016/S0022-2860(01)00471-9

Journal of Molecular Structure 570 ꢀ2001) 129±136
www.elsevier.com/locate/molstruc
Crystal structures of copperꢀII) complexes of 2-formylpyridine
substituted thiosemicarbazones; the ®rst example of a coordinated
thiosemicarbazone with a thiol function
a,
a
a
a
b
*
D.X. West , J.K. Swearingen , T.J. Romack , I.S. Billeh , J.P. Jasinski ,
Y. Lib, R.J. Staplesc
aDepartment of Chemistry, Illinois State University, Normal, IL 61790-4160, USA
bDepartment of Chemistry, Keene State College, Keene, NH 03435, USA
cDepartment of Chemistry, Harvard University, Cambridge, MA 02138, USA
Received 10 August 2000; accepted 9 January 2001
Abstract
The crystal structures of two 5-coordinate copperꢀII) complexes containing neutral, tridentate 2-formylpyridine
Nꢀ4)-substituted thiosemicarbazones have been determined. 2-Formylpyridine Nꢀ4)-cyclohexylthiosemicarbazone, HFo4CHex
coordinates via the pyridine nitrogen, imine nitrogen and thione sulfur with two chloro ligands to produce [CuꢀHFo4CHex)Cl2].
Similarly, 2-formylpyridine 3-ꢀ4-methylpiperazine)thiosemicarbazone, HFoppz4M, produces [CuꢀHFoppz4M)Cl2] with one
major difference; rather than the expected thione form of the thiosemicarbazone moiety, it coordinates as the thiol isomer. Both
complexes are close to a square pyramid structure with axial and equatorial chloro ligands and the thiosemicarbazone moieties
of both ligands nearly planar. Also included is the crystal structure of N-cyclohexylthiosemicarbazide, CHextsc. q 2001
Elsevier Science B.V. All rights reserved.
Keywords: Crystal structure; Heterocyclic thiosemicarbazones; CopperꢀII); Thione/thiol
1. Introduction
in the 2435 cm21 spectral region that is absent in the
spectra of the complexes with anionic thiosemicarba-
zone ligand, [CuꢀAcppz4M)Cl]. Although we have
been unable to produce suitable crystals of any of
those complexes, we have recently acquired a crystal
of copperꢀII) complex of the 2-formylpyridine
analogue, [CuꢀHFoppz4M)Cl2]. In addition, we
recently reported the spectroscopic characterization
of a series of cobaltꢀII,III), nickelꢀII) and copperꢀII)
complex of 2-formyl-, 2-acetyl- and 2-benzoylpyridine
Nꢀ4)-cyclohexylthiosemicarbazones, HFo4CHex, HA
c4CHex and HBz4CHex, respectively, along with the
analogous semicarbazones [5]. Itwas indicated thatdata
sets of crystals of both [CuꢀHAc4CHex)Cl2] and
Some time ago we reported the IR spectra of a
series of nickelꢀII) and copperꢀII) complexes of
neutral and monoanionic 2-acetylpyridine 3-ꢀ4-
methylpiperazine), HAcppz4M, and indicated that
the coordinated neutral ligand is in the thiol form
[1] rather than the commonly observed thione form
[2±4]. The spectra of [CuꢀHAcppz4M)Cl2] has a band
* Corresponding author. Department of Chemistry, University of
Washington, Box 351700, Seattle, WA 98195-1700, USA. Tel.:
11-206-616-4213; fax: 11-206-685-8665.
E-mail address: westdx@chem.washington.edu ꢀD.X. West).
0022-2860/01/$ - see front matter q 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-2860ꢀ01)00471-9

130
D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
[CuꢀBz4CHex)Cl] had been acquired, but solutions of
suf®cient accuracy had not been achieved with a stan-
dard diffractometer. However, data collected using a
Siemens SMART CCD based diffractometer operating
at 213 K has provided a suitable solution for [CuꢀHFo4-
CHex)Cl2]. These two crystals provide a useful contrast
of the two possible forms of a coordinated, neutral
heterocyclic thiosemicarbazone. In addition, we include
the structure of N-cyclohexylthiosemicarbazide,
CHextsc, inorder tocompare the coordinated condensa-
tion product with its starting material.
data collection. Cell parameters were retrieved using
smart [9] software and re®ned using saint on all
observed re¯ections. Data reduction was performed
using the saint software [10], which corrects for Lp
and decay. Absorption corrections were applied using
sadabs [11] supplied by George Sheldrick. The struc-
ture was solved by direct method using the shelxl-90
program [12] and re®ned by least squares method on
F2, shelxl-97 [13], incorporated in shelxtl-pc v
5.03 [14]. All non-hydrogen atoms for both crystals
were re®ned anisotropically, and hydrogens were
calculated by geometrical methods and re®ned as a
riding model.
A crystal of [CuꢀHFoppz4M)Cl2] was mounted in a
random orientation on a glass ®ber using a super glue
and measured with an Enraf-Nonius MACH3 diffract-
ometer. The structure was solved using maXus,
version 2.0 [15], software by Direct Methods with
the SIR92 [16] module and re®ned by full-matrix
least-square technique. Missing atoms were found
by difference-Fourier synthesis and non-hydrogen
atoms were re®ned anisotropically. The hydrogen
atoms on the carbon atoms were assigned ®xed
2. Experimental
CHextsc was prepared starting with cyclohexyla-
mine using the method described by Scovill [6].
HFoChex [5] was prepared by stirring ꢀand warming)
an equimolar mixture of 2-formylpyridine hydrazone
ꢀprepared by gently re¯uxing an excess of hydrazine
hydrate with 2-formylpyridine) and cyclohexyl
isothiocyanate in ethanol. HFoppz4M was prepared
by re¯uxing an excess of Nꢀ4)-methylpiperazine
with 2-formylpyridine S-methyldithiocarbazate, which
was prepared by the literature method [6]. The resulting
2-formylpyridine thiosemicarbazones were reacted in a
1:1 molar ratio with anhydrous copperꢀII) chloride in
boiling ethanol for two hours. All starting materials
were obtained from Aldrich Chemical Company,
Milwaukee, WI, and used as received.
ꢀ2
thermal parameters of Uiso ˆ 0:05 A ;placed in their
Ê
calculated positions ꢀC±H ˆ 0.96 A) and re®ned
using a riding model. The hydrogen atom on the sulfur
atom was found by a difference Fourier map and
re®ned isotropically. Scattering factors for both
compounds were taken from the International Tables
for X-ray Crystallography ꢀ1974, Vol. IV).
The olive green needle-like crystal of [CuꢀHFo4-
CHex)Cl2] and the yellow±orange crystal of CHextsc
were grown by slow evaporation of a 95% ethanol
solution and the selected crystals mounted on glass
®bers using silicon grease. Data for CHextsc were
acquired with a Rigaku AFC6S diffractometer with
graphite monochromatic MoKa radiation. The struc-
ture was solved by mithril [7] and re®ned by texsan
package [8]. Data for [CuꢀHFo4CHex)Cl2] were
collected using a Siemans SMART CCD based
diffractometer equipped with a LT-2 low-temperature
apparatus operating at 213 K. Data were measured
using c-scans of 0.38 per frame for 60 s, such that a
hemisphere was collected. A total of 2543 frames
3. Results and discussion
Table 1 contains a summary of the crystallographic
data for CHextsc, [CuꢀHFo4CHex)Cl2] and
[CuꢀHFoppz4M)Cl2] and selected bond distances
and angles are listed in Table 2. Perspective views
of CHextsc, [CuꢀHFo4CHex)Cl2] and [CuꢀHFop
pz4M)Cl2] are shown in Figs. 1±3, respectively.
3.1. Structure of CHextsc
A recent report on copperꢀII) complexes of Nꢀ4)-
substituted thiosemicarbazides included the structure
of N-methylthiosemicarbazide, Metsc [17]. The trans
arrangement of the thione sulfur and the hydrazinic
nitrogen with respect to the C1±N2 bond of CHextsc
is the same conformation found for Metsc [17] and for
Ê
were collected with a ®nal resolution of 0.85 A. The
®rst 50 frames were recollected at the end of data
collection to monitor for decay; the crystal used in
the diffraction study showed no decomposition during

D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
131
Table 1
Crystallographic data and re®nement results for cyclohexylthiosemicarbazide ꢀCHextsc): a copperꢀII) complex of 2-formylpyridine Nꢀ4)-
cyclohexylthiosemicarbazone, [CuꢀHFo4CHex)Cl2]; and a copperꢀII) complex of 2-formylpyridine 3-ꢀ4-methyl)piperazine, [CuꢀHFoppz)Cl2]
Empirical formula
Color: habit
C7H15N3S
C13H18Cl2CuN4S
Dark green needle
0.12 £ 0.05 £ 0.01
Triclinic
C13H19Cl2CuN5S
Green prism
0.25 £ 0.20 £ 0.15
Monoclinic
Yellow±orange prism
1.00 £ 0.40 £ 0.30
Monoclinic
Crystal size ꢀmm)
Crystal system
Space group
P21/a
P-1
C/2cꢀ#)
Unit cell dimensions
Ê
a ꢀA)
10.552ꢀ6)
6.076ꢀ5)
15.485ꢀ4)
90
6.7078ꢀ2)
9.0150ꢀ4)
13.9500ꢀ6)
82.190ꢀ1)
86.848ꢀ1)
79.456ꢀ1)
821.24ꢀ6)
2
22.204ꢀ3)
13.179ꢀ2)
12.587ꢀ2)
90
Ê
b ꢀA)
Ê
c ꢀA)
a ꢀ8)
b ꢀ8)
g ꢀ8)
108.20ꢀ2)
90
106.90ꢀ1)
90
Ê 3
Volume ꢀA )
943.2ꢀ8)
4
173.28
3524.1ꢀ2)
8
411.8
Z
Formula weight
396.81
Density ꢀcalcd.), ꢀg/cm3)
Absorption coef®cient ꢀmm21
Fꢀ000)
Goodnes-of-®t on F2
u range for data collection, 8
Limiting indices
1.220
1.605
1.533
)
2.76
1.780
1.664
376
1.964
406
1.213
1688
6.039
1.00 to 27.50
0 # h # 12
0 # k # 7
218 # l # 18
2490
2.32 to 24.78
26 # h # 7
210 # k # 10
216 # l # 16
5324
1.55 to 27.50
0 # h # 28
0 # k # 17
216 # l # 16
8922
Re¯ections collected
Independent re¯ections
Ê 23
2369 ꢀRint ˆ 0.030)
0.19
2572 ꢀRint ˆ 0.0359)
0.360
4045 ꢀRint ˆ 0.017)
2.29
Largest diff. Peak ꢀeA
)
)
Ê 23
Largest diff. Hole ꢀeA
R [I . 2sꢀI)]
Rw
20.18
0.037
20.368
0.0469
20.45
0.0543
0.031
0.0795
0.147
Ê
thiosemicarbazide [18,19]. This arrangement is stabi-
lized by weak hydrogen bonding between the amide
hydrogen, N1H1, and the hydrazinic nitrogen, N3,
which was also present in Metsc [17] and thiose-
micarbazide [18,19]. There is also intermolecular
hydrogen bonding with the strongest interaction
between N2H2 and S10 ꢀi.e. dꢀN2±H2) ˆ 0.83ꢀ2),
dꢀH2´´´S10) ˆ 2.51ꢀ2) and dꢀN2´´´S10) ˆ 3.311ꢀ2)
1.693ꢀ3) and 1.325ꢀ3) A for CHextsc. The only bond
angles of CHextsc and Metsc that differ signi®cantly
are the following: for CHextsc, S1±C1±
N2 ˆ 119.5ꢀ2) and N1±C1±N2 ˆ 116.8ꢀ2)8 and for
Metsc, S1±C1±N2 ˆ 117.8ꢀ3) and S1±C1±N2 ˆ
118.4ꢀ2)8.CHextsc is rather planar as demonstrated by
the following torsion angles: N1±C1±N2±N3, 12.6ꢀ3),
S1±C1±N2±N3, 2168.7ꢀ2) and S1±C1±N1±C2,
21.4ꢀ4)8.
Ê
A)that results in the formation of a dimer, which is
similar structurally to the dimers found for thioureas
[20]. However, the extent of hydrogen bonding inter-
actions for CHextsc is considerably less than found
for Metsc [17] and is probably due to the bulkiness of
the cyclohexyl group.
The most noticeable difference between the average
bond distances of the two crystallographically unique
forms of Metsc [17] and the bond distances in CHextsc
are the S1±C1 and N3±C1 bonds. In Metsc S1±C1 and
3.2. Structure of [Cu6HFo4CHex)Cl2] and
[Cu6HFoppz4M)Cl2]
Although isolation with anionic ligands is common
forcomplexesof2-formyl-,2-acetyl-and2-benzoylpyr-
idine Nꢀ4)-dialkyl- and 3-azacyclothiosemicarbazones,
particularly when base is added [21], it is considerably
less common for heterocyclic Nꢀ4)-alkyl- [4] and
Nꢀ4)-arylthiosemicarbazones [22]. Five-coordinate
Ê
N3±C1 average 1.718ꢀ4) and 1.302ꢀ6) A compared to

132
D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
Table 2
Selected bond length ꢀA) and angles ꢀ8) for CHextsc, 1, [CuꢀHFo4CHex)Cl2], 2 and [CuꢀHFoppz4M)Cl2], 3
Ê
Bond
1
Bond
2
3
Cu±Cl1
Cu±Cl2
Cu±S
2.2225ꢀ12)
2.5985ꢀ13)
2.2997ꢀ13)
2.037ꢀ4)
1.984ꢀ3)
1.697ꢀ5)
1.279ꢀ5)
1.351ꢀ5)
1.363ꢀ5)
1.323ꢀ5)
2.247ꢀ3)
2.757ꢀ3)
2.275ꢀ3)
2.038ꢀ8)
1.972ꢀ7)
1.740ꢀ9)
1.30ꢀ2)
Cu±N1
Cu±N2
S±C7
S1±C1
1.693ꢀ3)
N2±C6
N2±N3
N3±C7
N4±C7
N2±N3
N2±C1
N1±C1
1.415ꢀ3)
1.350ꢀ3)
1.325ꢀ3)
1.35ꢀ2)
1.32ꢀ2)
1.36ꢀ2)
Angle
Cl2±Cu±Cl1
Cl2±Cu±S
Cl2±Cu±N2
Cl2±Cu±N1
Cl1±Cu±S
Cl1±Cu±N2
Cl1±Cu±N1
S±Cu±N2
99.96ꢀ5)
103.7ꢀ1)
100.0ꢀ1)
90.7ꢀ3)
100.76ꢀ5)
93.57ꢀ11)
90.7ꢀ1)
87.1ꢀ3)
96.02ꢀ5)
166.22ꢀ11)
97.91ꢀ1)
83.91ꢀ11)
160.7ꢀ1)
78.84ꢀ14)
96.9ꢀ1)
96.8ꢀ1)
165.4ꢀ3)
97.3ꢀ3)
82.9ꢀ3)
S±Cu±N1
162.2ꢀ3)
80.8ꢀ3)
95.4ꢀ3)
N1±Cu±N2
Cu±S±C7
Cu±N2±C6
Cu±N2±N3
C5±C6±N2
C6±N2±N3
N2±N3±C7
N3±C7±S
118.1ꢀ3)
119.8ꢀ3)
114.8ꢀ4)
122.0ꢀ4)
117.3ꢀ3)
121.2ꢀ3)
114.9ꢀ4)
123.9ꢀ3)
115.5ꢀ7)
125.0ꢀ6)
116.8ꢀ8)
119.5ꢀ8)
111.3ꢀ7)
125.1ꢀ7)
116.0ꢀ8)
118.9ꢀ7)
N3±N2±C1
S1±C1±N2
N1±C1±N2
S1±C1±N1
119.2ꢀ2)
119.5ꢀ2)
116.8ꢀ2)
123.7ꢀ2)
N3±C7±N4
N4±C7±S
[CuꢀHFo4CHex)Cl2] and [CuꢀHFop pz4M)Cl2] are
isolated from boiling ethanol with coordination of
the thiosemicarbazone ligand via the thione or thiol
sulfur, respectively, the pyridyl nitrogen, and imine
nitrogen with one chloro ligand in a basal position
of an approximately square pyramidal structure. The
tridentate thiosemicarbazone ligand occupies three
equatorial positions, and the geometrical parameters
t, i.e. t ˆ ꢀb 2 a†=160[23], where a and b are the
N1±Cu±S1 and Cl1±Cu±N2 bond angles, respec-
tively, has a value of 0.09 and 0.05 for [CuꢀHFo4-
CHex)Cl2] and [CuꢀHFoppz4M)Cl2], respectively,
indicating small deviations from square pyramidal
chemistry. The second chloro ligand, Cl2, has a longer
Cu±Cl bond and is apical with angles to the larger
planar donor atoms ꢀi.e. S, Cl) $ 1008 and the angles
to the two nitrogens closer to 908.
A comparison of the copperꢀII)±thiosemicarbazone
ligand bond distances of the two complexes, Table 2,
as well as a similar complex of 2-benzoylpyridine
Nꢀ4)-propylthiosemicarbazone, [CuꢀHBz4P)Cl2] [4],
shows the following: there is no difference in the
Cu±N1 distances; [CuꢀHFoppz4M)Cl2] has the
shortest Cu±N2 and Cu±S distances, 1.927ꢀ7) and
Ê
2.275ꢀ3) A and [CuꢀHBz4P)Cl2] has the longest Cu±
Ê
N2 bond, 2.001ꢀ4) A and [CuꢀHFo4CHex)Cl2] the
Ê
longest Cu±S bond, 2.2997ꢀ13) A. The shorter Cu±
S bond for the thiol sulfur compared to the thione
sulfur is different than found for a nickelꢀII) complex
with neutral and anionic tridentate ligands,
[NiꢀHAm4DH)ꢀAm4DH)]ClO4 where HAm4DH is
2-pyridineformamide thiosemicarbazone, which
have equivalent Ni±S bond distances [24]. Greater
variation occurs for the Cu±Cl bonds; both bonds

D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
133
Fig. 1. ortep drawings of CHextsc with atom numbering scheme and displacement ellipsoids at 50% probability level.
are signi®cantly longer in [CuꢀHFoppz4M)Cl2], and
[CuꢀHFo4CHex)Cl2] has the shortest Cu±Cl bonds,
Table 2. The bond angles about the copperꢀII) center
are essentially the same for [CuꢀHFo4CHex)Cl2] and
[CuꢀHBz4P)Cl2], but [CuꢀHFoppz4M)Cl2] is some-
what different. In particular, Cl2±Cu±Cl1 is about
38 larger, and Cl2±Cu±N2 and Cl2±Cu±N1 about
38 smaller. Therefore, whether the sulfur is thiol or
thione does not seem to make a large difference in its
bond angles about the copperꢀII) center, and variation
Fig. 2. ortep drawings of [CuꢀHFo4CHex)Cl2] with atom numbering scheme and displacement ellipsoids at 50% probability level.

134
D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
Fig. 3. ortep drawings of [CuꢀHFoppz4M)Cl2] with atom numbering scheme and displacement ellipsoids at 50% probability level.
might be due in part to the difference between azacylic
and Nꢀ4)-alkyl thiosemicarbazones.
As expected, greater differences occur for the bond
distances of the thiosemicarbazone moiety and, in
particular, for C7±S, which aids in distinguishing
between the thione and thiol forms. The thiol C7±S
not involved in signi®cant intermolecular interactions.
The N3±C7 bond is formally a single bond in the
thione form of a thiosemicarbazone and a double
bond in the thiol and thiolato forms. This is consistent
Ê
with bond distances of 1.363ꢀ5) and 1.366ꢀ7) A for
[CuꢀHFo4CHex)Cl2] and [CuꢀHBz4P)Cl2], respec-
tively, and [CuꢀHFoppz4M)Cl2] and [CuꢀBzhex-
Ê
bond in [CuꢀHFoppz4M)Cl2] is 1.740ꢀ9) A compared
Ê
to 1.697ꢀ5) and 1.698ꢀ5) A for the thione C7±S bond
Ê
im)Cl] have values of 1.32ꢀ2) and 1.336ꢀ10) A.
in [CiꢀHFo4CHex)Cl2] and [CuꢀHBz4P)Cl2], respec-
tively. The thiol bond C±S distance is comparable to
Ê
the thiolato C7±S bond distance of 1.750ꢀ9) A for
[CiꢀBzhexim)Cl] where Bzhexim is the anion of
2-benzoylpyridine 3-hexamethyleneiminylthiosemi-
carbazone [4]. In addition, the S±H bond distance
However, all C±N bonds are shorter than a formal
C±N single bond due to delocalization of electron
density through the thiosemicarbazone moiety. The
other thiosemicarbazone bond distances are within
the combined e.s.d. values of the two complexes of
this study. Also, the bond distances in CHextsc and
[CuꢀHFo4CHex)Cl2], Table 2, are very similar except
Ê
was found to be 0.960ꢀ3) A, and this hydrogen is

D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
135
when the formal bond orders are different, i.e. N2±
N3. Further, there is not much variation in the bond
angles between these two compounds.
Although in [CuꢀHFoppz4M)Cl2] the mean plane
deviation of coordination plane, S1±C1±N2±N1, is
centers of an adjacent dimer resulting in a weak
chain of dimers. This ªeclipsedº stacking also
precludes strong intermolecular hydrogen bonding
interactions by either N3H or N4H. Fig. 4 shows
that other than the cyclohexyl group, [CuꢀHFo4-
CHex)Cl2], like [CuꢀHFoppz4M)Cl2], appears to be
quite planar.
Ê
only 0.0012 A, N2 and N1 are 0.0832ꢀ0.0069) and
Ê
20.0776ꢀ0.0071) A out of the plane and further, Cu
Ê
is 0.2185ꢀ0.0011) A out of the plane. The mean plane
of the thiosemicarbazone moiety, S1±N4±C7±N3±
Ê
N2±C6, is 0.0020 A and is nearly coplanar to the
The structure of Nꢀ4)-cyclohexylthiosemicarbazide
is similar to that of Nꢀ4)-methylthiosemicarbazide
except that the bulkier cyclic ring causes differences
in bond distances and angles in the thioamide portion
of the molecule, as well as differences in the extent of
hydrogen bonding. The two copperꢀII) compounds are
the second and third 5-coordinate square pyramid
complexes reported, and [CuꢀHFoppz4M)Cl2] is the
®rst thiosemicarbazone found in the thiol form in the
solid state. Finally, [CuꢀHFo4CHex)Cl2] packs in an
eclipsed manner in contrast to the chain, non-eclipsed
pacing of [CuꢀHBz4P)Cl2].
Supplementary material. Crystallographic data for
C7H15N3S ꢀCHextsc), CCDC#147583, C13H18Cl2CuN4S
ꢀ[CuꢀHFo4CHex)Cl2]), CCDC#147584, and for
C13H19Cl2CuN5S ꢀ[CuꢀHFoppz4M)Cl2]) CCDC#147
585 have been deposited with the Cambridge Crystal-
lographic Data Centre as supplementary publication no.
CCDC-1003/m. Copies of available material can be
S1±C1±N2±N1 plane, forming an angle of
175.6ꢀ4.2)8. The mean plane of the pyridine ring has
an angle of 6.67ꢀ3.07)8 with the S1±C1±N2±N1
plane and 177.7ꢀ4.5)8 with the thiosemicarbazone
plane showing that the thiol form of a thiosemicarba-
zone, like the thione form, retains its near planarity on
coordination.
The packing of [CuꢀHFo4CHex)Cl2] suggests weak
interactions between molecules via bridging by the
basal chloro ligand. This bridging causes a stacking
of the molecules in an ªeclipsedº arrangement, Fig. 4.
This packing is substantially different from that found
for [CuꢀHBz4P)Cl2] ꢀªnon-eclipsedº) in which each
molecule has a 6th donor to form a dimer and each
Clꢀ2) is positioned so that it interacts weakly with
Nꢀ3)H and Nꢀ4)H of the closest of the copperꢀII)
Fig. 4. Packing diagram for [CuꢀHFo4CHex)Cl2] showing `eclipsed' arrangement.

136
D.X. West et al. / Journal of Molecular Structure 570 62001) 129±136
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