Chemistry of functionalized thiolates: Syntheses and structures of neutral, monomeric [Zn(SC6H4X-4)2(N-N)], where X=H, NH2 and OH, and (N-N)=nitrogen bases 2,2′-bpy, phen and tmen

Article abstract of DOI:10.1016/S0020-1693(99)00267-4

Six neutral monomers of the type [Zn(SC₆H₄X-4)₂(N-N)] (where X=H, NH₂, OH; (N-N)=tetramethylethylenediamine (tmen); 2,2′-bipyridyl (bpy) and 1,10-phenanthroline (phen)) have been synthesized in quantitative yield by reacting bis(4-substituted benzenethiolato)zinc(II) with an equimolar amount of the dinitrogen bases. The crystal and molecular structures of all the compounds were determined by X-ray crystallography. A simple neutral compound [Zn(SPh)₂(bpy)] was also prepared for comparison. The compounds show some interesting X-HS (where X=O or N) hydrogen bonding pattern in the solid state.

Full text of DOI:10.1016/S0020-1693(99)00267-4

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 295 (1999) 9–17
Chemistry of functionalized thiolates: syntheses and structures of
neutral, monomeric [Zn(SC6H4X-4)2(NꢀN)], where X=H, NH2
and OH, and (NꢀN)=nitrogen bases 2,2%-bpy, phen and tmen
K.S. Anjali, Jeyagowry T. Sampanthar, Jagadese J. Vittal *
Department of Chemistry, National Uni6ersity of Singapore, Kent Ridge, Singapore 119 260, Singapore
Received 12 February 1999; accepted 18 June 1999
Abstract
Six neutral monomers of the type [Zn(SC6H4X-4)2(NꢀN)] (where X=H, NH2, OH; (NꢀN)=tetramethylethylenediamine
(tmen); 2,2%-bipyridyl (bpy) and 1,10-phenanthroline (phen)) have been synthesized in quantitative yield by reacting bis(4-substi-
tuted benzenethiolato)zinc(II) with an equimolar amount of the dinitrogen bases. The crystal and molecular structures of all the
compounds were determined by X-ray crystallography. A simple neutral compound [Zn(SPh)2(bpy)] was also prepared for
comparison. The compounds show some interesting XꢀH···S (where X=O or N) hydrogen bonding pattern in the solid state.
© 1999 Elsevier Science S.A. All rights reserved.
Keywords: Crystal structures; Zinc complexes; Thiolate complexes
1. Introduction
properties of 4-substituted benzene thiolates, 4-XC6H4-
S− (X=NH2, OH). The purpose is threefold: (1) To
understand how the structure of metal-thiolates is af-
fected by the functional groups at the para positions.
(2) To investigate whether there is any outersphere
coordination of these proton donor–acceptor groups
leading to interesting hydrogen bonding patterns. (3)
To use these functional groups for further reactions
with the metal ions. As a part of the program, we
report here the syntheses and structures of a series of
neutral, monomeric zinc compounds, [Zn(SC6H4X-
4)2(NꢀN)], where X=H, NH2, OH; (NꢀN)=te-
tramethylethylenediamine (tmen), 2,2%-bipyridyl (bpy)
and 1,10-phenanthroline (phen). The influence of
NꢀH···S and OꢀH···S hydrogen bonding on the packing
patterns in the crystal structures has been discussed in
detail.
Several monomeric zinc compounds of the type
ZnN2S2 have been studied as bioinorganic models [1] of
[Zn(cys-S)2(his)2] sites found in zinc fingers and
proteins involved in gene regulation [2]. Such
monomers with modified thiolate ligands have also
been considered as precursors for MOCVD techniques
[3]. Of late there has been interest in metal-containing
compounds bearing ligands with reactive functionality
not available for coordination to the central metal [4].
The external functional group can be used to transform
the molecules into useful materials. In biological sys-
tems, the protein superstructure serves as the ultimate
functional group. In this context, the N–H···S hydro-
gen bond formed between sulfur on the cysteine and
amine or amide group in the main chain of the peptide,
has been particularly notable for electron transfer
metalloproteins, cytochrome P-450 and chloroperoxi-
dase [5,6]. A few interesting inorganic systems dealing
with NꢀH···S hydrogen bonding have been reported as
models for metallothioneins [7]. Recently we have
started a research program to investigate the ligand
2. Experimental
2.1. General methods
The materials used in the syntheses were obtained
commercially and used as received. The compounds
* Corresponding author. Tel.: +65-874 2975; fax: +65-779 1691.
0020-1693/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00267-4

10
K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
warmed with stirring until the starting materials dis-
solved completely. The clear solution obtained was left
undisturbed at 0°C to obtain very light cream multi-
faceted crystals. The crystals were decanted, washed
with MeOH and dried in air. Yield: 0.15 g (72%). Anal.
Calc. for Zn S2C18H28N4: C, 50.29; H, 6.56; N, 13.03.
1
Found: C, 50.08; H, 6.01; N, 12.56%. H NMR (d6-
DMSO): l 7.03 (d, J=7 Hz, 4H, 2,2%), 6.29 (d, J=8
Hz, 4H, 3,3%), 4.55 (s, 4H, 5), 2.60 (s, 4H, 6,6%), 2.30 (s,
12H, 7,7%). 13C NMR (d6-DMSO): l 143.77 (1), 132.85
(2,2%), 126.89 (4), 115.45 (3,3%), 56.37 (6,6%), 46.62 (7,7%).
Scheme 1. Numbering scheme of the ligands.
2.2.3. Synthesis of [Zn(SC6H4NH2-4)2(bpy)] (3)
The synthesis was carried out similarly to that of 2
using bpy instead of tmen. Yield: 0.16 g (73%). Single
crystals were grown by dissolving the compound in a
large excess of warm CH3CN and leaving to cool. Anal.
Calc. for ZnS2C22H20N4: C, 56.23; H, 4.29; N, 11.92.
[Zn(SC6H4NH2-4)2] and [Zn(SC6H4OH-4)2] were pre-
pared similarly to [Zn(SC6H5)2] [8]. The solvents were
,
dried over 3 A molecular sieves and degassed with N2
prior to use. All the preparations were carried out
under N2. The Microanalytical Laboratory at NUS
performed the microanalyses. The yields are reported
1
Found: C, 55.96; H, 3.99; N, 12.05%. H NMR (d6-
DMSO): l 8.67 (d, J=4 Hz, 2H, 6,6%), 8.43 (d, J=8
Hz, 2H, 9,9%), 8.13 (br, 2H, 7,7%), 7.65 (br, 2H, 8,8%),
6.69 (br, 4H, 2,2%), 6.12 (d, J=7 Hz, 4H, 3,3%), 4.47 (s,
4H, 5). 13C NMR (d6-DMSO): l 149.89 (6,6%), 143.76
(1,8,8%), 134.22 (7,7%), 132.96 (2,2%), 125.80 (4), 120.72
(9,9%), 114.10 (3,3%).
1
with respect to the metal salts. 13C{1H} and H NMR
spectra were recorded on a Bruker ACF 300 MHz
using TMS as internal reference at 25°C. Assignment of
1H and 13C NMR data of these complexes is based on
those of similar complexes previously reported [9]. The
1
numbering scheme used in the assignment of H and
13C NMR chemical shifts is shown in Scheme 1.
In the 13C NMR spectra of compounds 1–7, the
chemical shifts correspond to C9 and C9% for phen, and
C10 and C10% for phen and bpy ligands were not
detected.
2.2.4. Synthesis of [Zn(SC6H4NH2-4)2(phen)] (4)
1,10-Phenanthroline was used in place of tmen, oth-
erwise the synthetic procedure was similar to that of 2.
Yield: 0.20 g (86%). Yellowish orange crystals were
grown by dissolving the compound in DMSO and
layering with water. Anal. Calc. for ZnS2C24H20N4: C,
58.36; H, 4.08; N, 11.34. Found: C, 58.04; H, 4.01; N,
2.2. Syntheses
1
11.06%. H NMR (d6-DMSO): l 9.02 (br, 2H, 6,6%),
2.2.1. Synthesis of [Zn(SC6H5)2(bpy)] (1)
8.77 (br, 2H 8,8%), 8.13 (s, 2H, 11,11%), 8.02 (br, 2H,
7,7%), 6.49 (br, 4H, 2,2%), 5.85 (br, 2H, 3,3%); 4.35 (br,
4H, 5). 13C NMR (d6-DMSO): l 149.08 (6,6%), 143.89
(1), 139.33 (8,8%), 132.87 (2,2%), 128.42 (11,11%), 126.77
(4,4%), 125.34 (7,7%), 113.73 (3,3%).
Neutral zinc thiolate Zn(SPh)2 (0.34 g, 1.19 mmol)
was dissolved in 8 ml of DMF to which was added bpy
(0.19 g, 1.23 mmol) in 10 ml of MeOH. The clear
yellow solution obtained was layered with 15 ml of
Et2O and left undisturbed at 0°C to obtain cream
colored crystals. The crystals were decanted, washed
with MeOH and dried in air. Yield: 0.39 g (74%). Anal.
Calc. for ZnS2C22H18N2: C, 60.07; H, 4.12; N, 6.37.
Found: C, 59.89; H, 4.39; N, 6.47%. 1H NMR (d6-
DMSO): l 8.22 (br, 2H, 6,6%), 7.99 (d, J=7 Hz, 2H,
9,9%), 7.69 (br, 2H, 7,7%), 7.20 (br, 2H, 8,8%), 6.65 (br,
4H, 2,2%), 6.34 (br, 6H, 3,3% and 4). 13C NMR (d6-
DMSO): l 150.20 (1), 148.64 (6,6%), 142.35 (8,8%), 132.50
(2,2%), 127.41 (3,3%), 126.40 (7,7%), 125.32 (4), 121.97
(9,9%).
2.2.5. Synthesis of [Zn(SC6H4OH-4)2(tmen)] (5)
The neutral [Zn(SC6H4OH-4)2] prepared in situ
[ZnCl2 (0.60 g, 4.4 mmol), Na (0.20 g, 8.88 mmol),
HSC6H4OH (1.12 g, 8.87 mmol)] was added to tmen
(0.67 ml, 4.44 mmol) in 6 ml of CH3CN and stirred for
about 30 min. The white precipitate obtained was
filtered, washed with water and vacuum dried. Yield:
1.75 g (91.8%). Anal. Calc. for ZnS2C18H26N2O2: C,
50.05; H, 6.07; N, 6.49. Found: C, 49.84; H, 6.07; N,
1
6.70%. H NMR (d6-DMSO): l 7.12 (d, J=8 Hz, 4H,
2.2.2. Synthesis of [Zn(SC6H4NH2-4)2(tmen)] (2)
To a suspension of [Zn(SC6H4NH2-4)2] (0.15 g, 0.48
mmol) in 3.0 ml of CH3CN was added tmen (0.07 ml,
0.49 mmol) via a syringe. The resulting mixture was
2,2%), 6.43 (d, J=8 Hz, 4H, 3,3%), 3.25 (br, 2H, 5), 2.63
(s, 12H, 6,6%), 2.33 (s, 12H, 7,7%). 13C NMR (d6-DMSO):
l 153.02 (1), 133.09 (2,2%), 128.70 (4), 115.02 (3,3%) 56.33
(6,6%), 46.63 (7,7%).

K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
11
2.2.6. Synthesis of [Zn(SC6H4OH-4)2(bpy)]·0.5H2O (6)
The neutral [Zn(SC6H4OH-4)2] was prepared in situ
by adding ZnCl2 (0.38 g, 2.78 mmol) to NaSC6H4OH
prepared from HSC6H4OH (0.70 g, 5.5 mmol), Na (0.13
g, 5.5 mmol) in 3 ml of MeOH. To this, bpy (0.43 g, 2.7
mmol) in 6 ml of MeOH was added. The yellow product
obtained was warmed after adding an excess of CH3CN
and a few drops of water. The clear yellow solution
obtained was concentrated and cooled for 5 h. Bright
yellow crystals obtained were collected by filtration and
dried in air. Yield: 0.81 g (60.5%). Anal. Calc. for
ZnS2C22H19N2O2.5: C, 54.95; H, 3.98; N, 5.83. Found:
C, 55.31; H, 3.78; N, 5.88%. 1H NMR (CD3CN): l 8.63
(d, J=5 Hz, 2H, 6,6%), 8.14 (br, 4H, 9,9%,7,7%), 7.64 (br,
2H, 8,8%), 6.75 (d, J=9 Hz, 4H, 2,2%), 6.20 (d, J=9 Hz,
4H, 3,3%), 3.40 (br, 2H, 5). 13C NMR (CD3CN): l 153.07
(1); 148.11 (6,6%), 140.24 (8,8%), 133.46 (2,2%), 128.16
(7,7%), 126.02 (4), 121.38 (9,9%), 114.69 (3,3%).
2.3.1. Treatment of hydrogen atoms
The CꢀH hydrogen atoms were placed in the calcu-
lated positions and their thermal parameters were al-
lowed to ride on the carbon atoms to which they were
attached. All the NꢀH and OꢀH were located in the
difference Fourier methods. However, the positional
and isotropic thermal parameters of a few hydrogen
atoms were refined. The positional parameters were
refined for the NꢀH protons in 3 and 4 and the same
parameters were fixed for the rest. Individual isotropic
thermal parameters were fixed for the hydrogen atoms
in 4, 6 and 7, common isotropic temperature factors
were refined in 3 and riding models were used for the
rest. A half molecule of water was located in 6 and the
positions of the hydrogen atoms were constrained using
DFIX
.
3. Results and discussion
2.2.7. Synthesis of [Zn(SC6H4OH-4)2(phen)] (7)
The neutral zinc thiolate [Zn(SC6H4OH-4)2] was pre-
pared in situ as described before (from ZnCl2 (0.62 g,
4.57 mmol), Na (0.21 g, 9.23 mmol), HSC6H4OH (1.16
g, 9.23 mmol) in 5 ml of MeOH). To this, phen (0.92 g,
4.62 mmol) was added in 5 ml of CH3CN while stirring.
The yellowish orange product was filtered, washed with
MeOH and vacuum dried. Single crystals were grown by
dissolving the compound in THF and layering with
petroleum ether. Yield: 1.65 g (73%). Anal. Calc. for
ZnS2C24H18N2O2: C, 58.13; H, 3.66; N, 5.65. Found: C,
3.1. Preparation of [Zn(SC6H4X-4)2(NꢀN)] (1–7)
The complexes 1–7 were prepared in a straightfor-
ward manner, by the reaction of the corresponding
neutral thiolates with the dinitrogen bases (Eq. (1)) and
isolated in 60–90% yield. The color of the crystals
varied from almost colorless for 1, 2 and 5, yellow for
6 to orange (3, 4 and 7). The isolated products were
found to be insoluble in cold acetonitrile, although they
were soluble in the reaction mixture before work-up.
These compounds are in general soluble in DMF,
DMSO and hot acetonitrile.
1
57.47; H, 3.72; N, 5.55%. H NMR (d6-DMSO): l 8.99
(br, 2H, 6,6%), 8.77 (d, J=8 Hz, 2H, 8,8%), 8.12 (s, 2H,
11,11%), 8.02 (br, 2H, 7,7%), 6.68 (br, 4H, 2,2%), 6.05 (br,
4H, 3,3%), 3.38 (br, 2H, 5). 13C NMR (d6-DMSO): l
152.88 (1), 149.17 (6,6%), 139.28 (8,8%), 133.21 (2,2%),
128.42 (11,11%), 126.76 (4), 125.34 (7,7%), 114.32 (3,3%).
Zn(SC6H4X-4)2+(NꢀN)“[Zn(SC6H4X-4)2(NꢀN)]
(1)
1H and 13C NMR spectroscopic methods were used
successfully to characterize the compounds in solution
(see Section 2) and are consistent with the proposed
monomer structure. The structures were further confi-
rmed by X-ray crystallography.
2.3. X-ray structure determinations
The diffraction experiments were carried out on a
Bruker AXS SMART CCD three-circle diffractometer
,
with a Mo Ka (u=0.71073 A) sealed tube at 23°C. The
3.2. Description of structures of 1–7
software used was: SMART [10] for collecting frames of
data, indexing reflections and determining lattice
parameters; SAINT [10] for integration of intensity of
reflections and scaling; SADABS [11] for absorption cor-
rection; and SHELXTL [12] for space group determina-
tion, structure solution and least-squares refinements on
F2. The space groups were determined from the system-
atic absences. The correctness of the choice of space
groups was confirmed by successful solution and refine-
ment of the structures. All the non-hydrogen atoms
were refined anisotropically. The Flack parameter for 5
was refined to −0.006(9). A summary of the crystallo-
graphic data and experimental details is given in Table
1.
The crystal and molecular structures of the com-
pounds 1–7 were determined by single crystal X-ray
diffraction techniques. Only compound 1 was found to
be discrete in the solid state. The rest of the compounds
have intermolecular interactions due to NꢀH···S and
OꢀH···S hydrogen bonding. Compounds 6 and 7 are
isomorphous and isostructural. Compounds 3 and 4
have similar arrangements of molecules in the crystal
lattice. However, they are not strictly isotypical. Com-
pound 5 crystallized in a chiral space group, P21 with
two independent molecules in the asymmetric unit.
Selected bond distances and angles are summarized in
Table 2.

Table 1
Crystal data and structure refinement for [Zn(SC6H4-X)2(NꢀN)] a
Compound
1
2
3
4
5
6
7
Formula
Weight
C22H18N2S2Zn
439.87
C18H28N4S2Zn
429.93
C22H20N4S2Zn
469.91
C24H20N4S2Zn
493.93
C18H26N2O2S2 Zn
431.90
C22H19N2O2.5S2Zn
480.88
C24H18N2O2S2Zn
495.89
Crystal system
Space group
triclinic
orthorhombic
Pbca
16.4520(2)
13.8102(2)
18.5102(2)
90
monoclinic
P21/c
9.5043(3)
21.3506(7)
10.7014(2)
90
96.785(1)
90
2156.35(11)
4
1.447
1.348
968
0.18×0.10×0.05
1.91–25.00
−105h511,
−255k525,
−125l57
10 272
monoclinic
P21/c
10.2763(2)
18.6353(2)
12.0741(2)
90
106.203(1)
90
2220.37(6)
4
1.478
1.313
1016
0.30×0.20×0.13
2.06–29.38
−105h513,
−185k524,
−165l516
13 749
monoclinic
P21
9.403
14.0426(2)
15.7482(2)
90
95.225(1)
90
2070.88(4)
4
1.385
1.401
904
0.40×0.20×0.20
1.95–29.31
−125h58,
−195k518,
−205l521
13 161
triclinic
triclinic
(
(
(
P1
P1
P1
,
a (A)
7.6516(2)
11.2320(3)
12.2055(4)
92.800(1)
90.536(1)
101.784(1)
1025.44(5)
2
9.4978(6)
10.7579(6)
12.0823(7)
67.743(1)
74.601(1)
75.315(1)
1085.2(1)
2
9.300(2)
,
b (A)
10.579(3)
12.264(3)
69.17(1)
77.47(2)
79.15(3)
1092.7(5)
2
1.507
1.339
508
0.40×0.20×0.13
1.80–29.30
−125h512,
−145k513,
−115l516
7155
,
c (A)
h (°)
i (°)
k (°)
90
90
3
/
,
V (A )
Z
4205.62(9)
8
1.358
1.375
1808
0.45×0.33×0.25
2.20–29.34
−225h520,
−115k518,
−255l523
24 625
Dcalc (g cm−3
)
1.425
1.410
452
0.30×0.25×0.10
2.43–29.25
−105h59,
−155k512,
−155l516
6423
1.472
1.347
494
0.40×0.33×0.15
1.85–29.45
−55h512,
−145k514,
−165l516
7057
v (mm−1
F(000)
)
Crystal size (mm3)
q Range (°)
Index ranges
295
Reflections collected
(
Independent reflections 4584 [Rint=0.0181]
Max./min. transmission 0.881/0.536
Data/restraints/parame- 4584/0/245
ters
5372 [Rint=0.0267]
0.746/0.608
5372/0/227
3736 [Rint=0.0611]
0.904/0.623
3736/13/276
5473 [Rint=0.0301]
0.862/0.672
5473/7/296
8388 [Rint=0.01931] 5002 [Rint=0.0160]
5083 [Rint=0.0306]
0.862/0.402
5083/0/285
0.813/0.577
8386/1/456
0.779/0.635
5002/3/281
Goodness-of-fit on F2
R[Fo]4|(Fo)]
1.030
1.056
1.066
1.023
1.025
1.100
1.048
R1=0.0459,
wR2=0.0972
R1=0.0728,
wR2=0.1102
0.0028(12)
R1=0.0395,
wR2=0.0802
R1=0.0582,
wR2=0.0877
0.00009(10)
0.301 and −0.302
R1=0.0595,
wR2 =0.0842
R1=0.1135,
wR2=0.0967
0.0019(3)
R1=0.0430,
wR2=0.0850
R1=0.0744,
wR2=0.0953
R1=0.0354,
wR2=0.0748
R1=0.0465,
wR2=0.0840
0.0011(3)
R1=0.0435,
wR2=0.1026
R1=0.0573,
wR2=0.1130
R1=0.0560,
wR2=0.1314
R1=0.0711,
wR2=0.1378
0.0015(13)
R on all data
Extinction coefficient
Largest difference peak 0.427 and −0.323
0.296 and −0.268
0.399 and −0.354
0.449 and −0.349
0.379 and −0.425
0.851 and −0.976
−3
,
and hole (e A
)
]
a R1=S(ꢀꢀFoꢀ−ꢀFcꢀꢀ)/S(ꢀFoꢀ); wR2=[Sw(Fo2−Fc2)2/wFo4 1/2; Goodness-of-fit=[Sw(Fo2−Fc2)2/n−p]1/2, where n is the number of reflections and p is the number of parameters refined.

K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
13
OꢀH functional group (see below) and hence account
for the similar ZnꢀSꢀC angles.
3.2.2. Hydrogen bonding
The hydrogen bonding patterns present in the crys-
tals of 2–7 are shown at the bottom of Figs. 2–7 along
with the relevant hydrogen bonding parameters. The
NꢀH···S and OꢀH···S bonds observed are less than the
sum of the van der Waals radii for H and S (3.0–3.25
,
A) [14]. A search of the August 1998 release of the
Cambridge Structural Database [15] produced 67 hits
for the NꢀH···S interactions present in inorganic sys-
tems. The H···S and N···S distances are in the range
,
2.213–2.798 and 3.222–3.699 A, respectively. Similarly,
there were 20 hits for the OꢀH···S interactions present
Fig. 1. An ORTEP diagram of 1 showing the 50% probability of the
thermal ellipsoids and the numbering scheme.
3.2.1. Molecular structures
Some of the common features of the molecular ge-
ometries of 1–7 are summarized as follows. Two ben-
zenethiolates and a dinitrogen base provide a distorted
tetrahedral geometry around the central zinc atom. The
thermal ellipsoid plots for 1–7 and the packing dia-
grams for 2–7 are shown in Figs. 1–7. One of the two
benzenethiolate ligands adopts a different orientation
depending on the type of chelating dinitrogen base
attached to Zn(II). When (NꢀN) is planar as in bpy and
phen, one of the benzene thiolate rings is oriented just
above the dinitrogen base. Some of the relevant
parameters are given in Table 3. The interplanar angles
between the dinitrogen base and the benzenethiolate
vary from 13.5(3) to 32.3(1)°. The nonbonded distances
,
between these two p rings are in the range 3.02–4.37 A.
In 1, the metal atom is almost on the plane of the bpy
ring. When the para position of the benzenethiolate
contains the functional group OH or NH2, the zinc
metal is displaced towards the thiolate ring by 0.19–
,
0.412 A and further, the interplanar angles between the
rings were found to be smaller (13.5–23.7°) than in 1.
This is also reflected in the interplanar distances be-
tween the rings involved in p stacking as given in Table
3. Such intramolecular p stacking of benzene rings has
also been observed in many other systems. It appears
that these p–p interactions are responsible for the color
and luminescent properties observed in the solid state
[13].
The variations in ZnꢀS, ZnꢀN and SꢀC distances and
NꢀZnꢀN angles are normal and do not warrant any
further discussion. The SꢀZnꢀS angles vary from
97.1(1) to 100.7(1)°. Two types of ZnꢀSꢀC angles are
observed and the ZnꢀS(1)ꢀC(1A) angle is found to be
less than the ZnꢀS(2)ꢀC(1B) angle, in general. The
smaller ZnꢀSꢀC angles in 1, 3, 4 and 6 may be at-
tributed to intramolecular p–p interactions. The second
benzene thiolate ring in 7 is involved in intermolecular
p stacking as well as hydrogen bonding through the
Fig. 2. (a) Thermal ellipsoid plot and the numbering scheme for 2. (b)
Packing diagram of molecule 2. Relevant hydrogen-bonding distances
(A) and angles (°): S2···H3Di, 2.706, S2···N3i, 3.455(3);
,
S2···H3DiꢀN3i, 146.4; S1···H4Cii, 2.708; S1···N4ii, 3.534(2);
S1···H4CiiꢀN4ii, 161.4; S2···H4Diii, 2.677(2); S2···N4iii, 3.493(2);
i
S2···H4DiiiꢀN4iii, 158.7. Operators for generating equivalent atoms:
x−1/2, y, −z+1/2;
y−1/2, z.
ii
iii
−x+1/2, −y+1, z−1/2;
−x+1/2,

14
K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
Fig. 3. (a) An ORTEP diagram showing the number scheme in 3. (b)
Packing diagram of 3, viewed down the a-axis. Selected hydrogen
i
i
,
bonding distances (A) and angles (°): N3ꢀH3C···S2 ; 2.772, N3···S2 ,
3.606(3); N3ꢀH3C···S2i, 170.0. Operators for generation equivalent
i
atoms: −x+1, y−1/2, −z+1/2.
in the inorganic systems. The H···S and O···S distances
,
are in the range 2.085–2.856 and 3.095–3.548 A, re-
spectively. However, almost all the reported interac-
tions are between sulfur and hydrogen atoms of the
solvent molecule present in the crystal lattice.
In 2, three out of four NH2 hydrogen atoms are
involved in weak hydrogen bonding to S atoms. The
,
N···S distances, 3.455–3.534 A, are in the upper range
,
of 3.3–3.5 A of NꢀH···S hydrogen bonds observed [16]
in neutral organic compounds. The packing diagram of
the compound shown in Fig. 2 indicates a three-dimen-
sional hydrogen-bonding pattern. It appears that only
one out of four NH2 hydrogen atoms is involved in
NꢀH···S hydrogen bonding in 3. Fig. 3 shows the
one-dimensional polymer formed by the weak interac-
tion between NꢀH and S along the b-axis. The S atom
of thiolate not involved in the p stacking is intermolec-
ularly hydrogen bonded to one of the NH2 hydrogen
atoms of its counterpart from the neighboring molecule
in the lattice. The neutral monomer 4 is dimerized in
the solid-state through NꢀH···S hydrogen bonding as
shown in Fig. 4. Here, the hydrogen bonding is between
the S atom of the p stacked thiolate and the NꢀH of the
other thiolate ligand. The H···S distances, 2.751 and
,
2.953 A, indicate that the interaction is weak. Again, all
the NH2 hydrogen atoms are not utilized in hydrogen
bonding. The NꢀH···S bonds present in all these three
compounds (2–4) are indicative of weak bonding rela-
tive to the interactions observed between the cations
containing NꢀH groups and the anions containing
PhS− groups [7].

K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
15
Table 3
Selected non-bonding parameters
Compound
1
3
4
6
7
Interplanar angle between the thiolato ring and (NꢀN) (°)
32.3(1)
3.02–4.37
0.097
13.5(3)
3.1–3.71
0.412
14.2(1)
2.98–3.66
0.190
23.7(1)
3.12–4.21
0.210
18.3(2)
2.16–3.96
0.385
,
Distance between the thiolato and the (NꢀN) rings (A)
,
Displacement of Zn from the (NꢀN) plane (A)
Twist angle between the rings in bpy (°)
6.1(2)
2.8(3)
1.1(2)
The OꢀH···S hydrogen bonds present in 5 produce a
two-dimensional network as shown in Fig. 5. All the
OꢀH hydrogen atoms and a sulfur atom from each
independent molecule participate in OꢀH···S hydrogen
bonding. In other words, one of the two S atoms is
hydrogen bonded to two OꢀH hydrogens in the bc
plane (Fig. 5). The H···S and O···S distances are 2.428–
,
2.528 and 3.224–2.326 A, respectively. Similar to 4, 6 is
also present as a dimer in the solid state through
Fig. 5. (a) A perspective view of compound 5 showing 50% thermal
ellipsoids and the numbering scheme. Of the two independent
molecules in the asymmetric unit, only one is shown. (b) Two-dimen-
sional hydrogen bonding network present in 5. Selected hydrogen
i
Fig. 4. (a) An ORTEP view with 50% thermal ellipsoids showing the
,
bonding distances (A) and angles (°): S4···H1, 2.528; S2···H3 , 2.469;
S4···H2ii, 2.513; S2···H4ii, 2.428; S4···O1, 3.299(4); S2···O3i, 3.271(3);
S4···O2ii, 3.326(3); S2···O4ii, 3.224(3); S4···H1ꢀO1, 157.1;
S2···H3iꢀO3i, 166.0; S4···H2ii-O2ii, 171.3; S2···H4ii-O4ii, 164.0. Opera-
atom numbering scheme in 4. (b) Unit cell packing of 4. Selected
i
,
hydrogen bonding distances (A) and angles (°): N4ꢀH1···S1 , 2.751,
N4···S1i, 3.572(4), N4ꢀH1···S1i, 172.9. N3ꢀH2···S1ii, 2.953, N3···S1ii,
3.753(3), N3ꢀH2···S1ii, 166.0. Operators for generation equivalent
i
ii
tors for generating equivalent atoms: x, y, z+1; −x+1, y−1/2,
−z+1.
i
ii
atoms: 1−x, −y, 1−z; x, −y−0.5, z−0.5.

16
K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
Fig. 7. (a) Perspective view of 7 showing the numbering scheme. (b)
Ribbon-like one-dimensional linear polymer formed by OꢀH···S hy-
,
drogen bonding in 7. Selected hydrogen bonding distances (A) and
angles (°): H2O···S1i, 2.391; H1O···S2ii, 2.422; O2···S1i, 3.209(4);
O1···S2ii, 3.238(3); O2ꢀH2O···S1i, 174.9; O1ꢀH1O···S2ii, 173.7. Opera-
i
tors for generating equivalent atoms:
x, y−1, z.
−x, −y+1, −z;
ii
Fig. 6. (a) ORTEP view of compound 6 showing 50% probability
thermal ellipsoids. (b) The hydrogen bonding pattern in 6. Selected
i
,
hydrogen bonding distances (A) and angles (°): H31···O2 , 2.147;
H1O···S2ii, 2.419, H2O··· S1iii, 2.336; O3···O2i, 2.97(1); O1···S2ii,
3.234(3), O2···S1iii, 3.148(3); O3ꢀH31···O2i, 164.0; O1ꢀH1O···S2ii,
172.3; O2ꢀH2O···S1iii, 170.7. Operators for generating equivalent
the solid state. In the crystal structures of 5–7, the
H···S and O···S distances are in the range 2.336–2.528
i
ii
iii
atoms: x+1, y, z; x, y−1, z; −x, −y+1, −z.
,
and 3.148–3.326 A, respectively. These OꢀH···S
distances are shorter than the NꢀH···S distances
observed here.
OꢀH···S bonding. Furthermore, the oxygen atom of the
OH group involved in the hydrogen bonding interacts
with one of the hydrogen atoms of the half solvent
water molecule present in the lattice. The sulfur atoms
of the p stacked thiolate ligands are hydrogen bonded
to the OH groups of the neighboring thiolate ligand to
form a ring consisting of four [Zn(SC6H4OH-4)2(bpy)]
4. Summary and conclusions
In the series of zinc complexes reported here, we have
observed that the compounds containing intramolecular
p stacking are intensely colored compared to those
containing tmen ligands. In structurally similar
compounds, the XꢀH···S interactions greatly influence
the way these monomers pack in the crystal lattice,
resulting in the formation of dimers, linear polymers,
two-dimensional networks and three-dimensional
hydrogen bonded networks. The structural details
provided here on XꢀH···S hydrogen-bonding
interactions in structurally similar zinc complexes
suggest that such interactions could stabilize the
structure of zinc-binding sites in zinc containing
metalloproteins.
monomers. This results in the formation of
a
one-dimensional ribbon polymer as shown in Fig. 6.
The hydrogen bonding pattern in 7 is very similar to
that in 6 as shown in Fig. 7. In the absence of water in
.
the lattice, the benzene thiolate rings that are not
involved in intramolecular p interactions are brought
closer together to form dimers with intramolecular p
stacking through OꢀH···S hydrogen bonding. These
dimers further interact to form a ring comprising four
[Zn(SC6H4OH-4)2(phen)] monomers. These dimers and
tetramers alternate to form one-dimensional ribbons in

K.S. Anjali et al. / Inorganica Chimica Acta 295 (1999) 9–17
17
[4] For recent examples see: (a) T.J. Katz, L. Liu, N.D. Willmore,
J.M. Fox, A.L. Rheingold, S. Shi, C. Nuckolls, B.H. Rickman,
J. Am. Chem. Soc. 119 (1997) 10 054. (b) M.D. Westmeyer,
M.A. Massa, T.B. Rauchfuss, S.R. Wilson, J. Am. Chem. Soc.
120 (1998) 114.
5. Supplementary material
Complete details of crystallographic data in the form
of CIF files for the compounds 1–7 have been de-
posited with the Cambridge Structural Database.
[5] T. Okamura, S. Takamizawa, N. Ueyama, A. Nakamura, Inorg.
Chem. 37 (1998) 18 and Refs. therein.
[6] T. Ueno, Y. Kousumi, K. Yoshizawa-Kumagaye, K. Nakajima,
N. Ueyma, T. Okamura, A. Nakamura, J. Am. Chem. Soc. 120
(1998) 12 264 and Refs. therein.
Acknowledgements
[7] (a) W.P. Chung, J.C. Dewan, M.A. Walters, Inorg. Chem. 30
(1991) 4280. (b) W.P. Chung, J.C. Dewan, M.A. Walters, J. Am.
Chem. Soc. 113 (1991) 525. (c) M.A. Walters, J.C. Dewan, C.
Min, S. Pinto, Inorg. Chem. 30 (1991) 2656.
[8] P.A.W. Dean, J.J. Vittal, Y. Wu, Can. J. Chem. 70 (1992) 779.
[9] R. Castro, J.A. Garcia-vazquez, J. Romero, A. Sousa, Polyhe-
dron 12 (1993) 2241.
J.J.V. would like to thank National University of
Singapore for the research grant (Grant No.
RP970618).
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