Nickel(II) complexes of N -(dialkylcarbamothioyl)-4-nitrobenzamide as single-source precursors for the deposition of nanostructured nickel sulfide thin films by chemical vapor deposition

Article abstract of DOI:10.1080/00958972.2013.807921

Nickel(II) complexes of N-(di-alkyl-carbamothioyl)-4-nitrobenzamide (alkyl = ethyl or n-propyl) have been synthesized and characterized by infrared spectroscopy, elemental analysis, nuclear magnetic resonance spectroscopy, and mass spectrometry. The struc

Full text of DOI:10.1080/00958972.2013.807921

This article was downloaded by: [University of Waikato]
On: 03 June 2014, At: 04:57
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Coordination Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gcoo20
Nickel(II) complexes of N-
(dialkylcarbamothioyl)-4-
nitrobenzamide as single-source
precursors for the deposition of
nanostructured nickel sulfide thin films
by chemical vapor deposition
Sohail Saeed a , Naghmana Rashid a , Mohammad Azad Malik b ,
Paul O’Brien b & Wing-Tak Wong c
a Department of Chemistry , Allama Iqbal Open University ,
Islamabad , Pakistan
b Schools of Chemistry and of Materials , The University of
Manchester , Manchester , UK
c Department of Chemistry , The University of Hong Kong , Hong
Kong SAR , P.R. China
Accepted author version posted online: 22 May 2013.Published
online: 16 Jul 2013.
To cite this article: Sohail Saeed , Naghmana Rashid , Mohammad Azad Malik , Paul O’Brien
& Wing-Tak Wong (2013) Nickel(II) complexes of N-(dialkylcarbamothioyl)-4-nitrobenzamide
as single-source precursors for the deposition of nanostructured nickel sulfide thin films
by chemical vapor deposition, Journal of Coordination Chemistry, 66:16, 2788-2801, DOI:
10.1080/00958972.2013.807921
To link to this article: http://dx.doi.org/10.1080/00958972.2013.807921
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,

proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Journal of Coordination Chemistry, 2013
Vol. 66, No. 16, 2788–2801, http://dx.doi.org/10.1080/00958972.2013.807921
Nickel(II) complexes of N-(dialkylcarbamothioyl)-4-
nitrobenzamide as single-source precursors for the deposition
of nanostructured nickel sulfide thin films by chemical vapor
deposition
SOHAIL SAEED†, NAGHMANA RASHID†, MOHAMMAD AZAD MALIK‡,
PAUL O’BRIEN*‡ and WING-TAK WONG§
†Department of Chemistry, Allama Iqbal Open University, Islamabad, Pakistan
‡Schools of Chemistry and of Materials, The University of Manchester, Manchester, UK
§Department of Chemistry, The University of Hong Kong, Hong Kong SAR, P.R. China
(Received 13 October 2012; in final form 22 April 2013)
Nickel(II) complexes of N-(di-alkyl-carbamothioyl)-4-nitrobenzamide (alkyl = ethyl or n-propyl)
have been synthesized and characterized by infrared spectroscopy, elemental analysis, nuclear
magnetic resonance spectroscopy, and mass spectrometry. The structures of bis[N-(diet-
hylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2a) and bis[N-(dipropylcarbamothioyl)-4-nitrobenza-
mide]nickel(II) (2b) have been determined by X-ray crystallography. FTIR and NMR of the nickel
complexes showed the absence of the N–H proton resonance and the N–H stretch and shift of νC=O
and νC=S as expected. Both complexes have been used as single-source precursors for the deposi-
tion of nickel sulfide nanostructured thin films by aerosol-assisted chemical vapor deposition. The
nanostructured thin films were characterized by X-ray powder diffraction, scanning electron micros-
copy, energy dispersive X-ray analysis, and atomic force microscopy.
Keywords: Nickel complexes; Crystal structure; cis-Configuration; Thin films; AACVD; SEM
1. Introduction
There is growing interest in nanostructured and thin film materials and the design of the
metal coordination complexes to be used for the synthesis of these materials [1–7]. The
coordination chemistry and potential applications of such precursors have only been
explored in the last few decades. Acylthiourea ligands with presence of O, N, N′, and S
donors exhibit various coordination modes: (a) O and S bonded to M (monobasic
bidentate) [8], (b) only S bonded to M (neutral monodentate) [9], (c) O and N bonded to
M (neutral bidentate) [10], and (d) O and S bonded to M and N is bonded to M′
(monobasic bridging ligand) [11]. Substituted acylthiourea ligands, which do not form an
intramolecular hydrogen bond, tend to coordinate predominately in bidentate (S, O)
fashion to transition-metal ions through sulfur and acyl oxygen [11]. Examples for this
*Corresponding author. Email: paul.obrien@manchester.ac.uk
Ó 2013 Taylor & Francis

S. Saeed et al.
2789
type of coordination are mononuclear complexes [ML2], where M = Ni(II), Cu(II), Co(II),
Zn(II), Cd(II), Pt(II), and Pd(II) and L= substituted acylthiourea derivatives [12]. Coordina-
tion solely through sulfur is rare and so far only known for complexes with Au(I) [13],
Ag(I) [14], Hg(II) [15], and Cu(I) [16]. It has been suggested that intramolecular hydrogen
bonding exists between the thiourea N–H (where R/R′ = H) and the amidic O-donor to
form a six-membered ring, with the consequence that the ligands coordinate to metal cen-
ters in a monodentate fashion through sulfur [11].
There are relatively few reports on the deposition of nickel sulfide thin films from sin-
gle-source precursors by CVD. The phase diagram of the Ni–S system is more complex
than that of the Fe or Co sulfides. In this system, many crystalline phases and stoichiome-
tries have been reported including: Ni3+xS2, Ni3S2, Ni4+xS2, Ni6S5, Ni7S6, Ni9S8, NiS,
Ni3S4, and NiS2 [17–19]. Some compounds, for example, NiS and NiS2, have been studied
extensively, while for others only more limited information is available. NiS2 (Vaesite) is a
p-type semiconductor with a band gap of 0.5 eV [20]. It is potentially useful in photo elec-
trochemical solar cells [21, 22], I.R detectors [23], catalysis [24], and sensors [25]. It is
also used as a hydrodesulfuration catalyst and as a cathode material in rechargeable lithium
batteries [26]. Nomura et al. studied the growth of NiS1.03 from [Ni(S2CNEt2)2] on silicon
(111) substrates by low-pressure chemical vapor deposition (LP-CVD) [27]. Earlier,
O’Brien et al. have reported the deposition of nickel sulfide films from dithiocarbamate
compounds of the type [Ni(S2CNRR′)2], where RR′ = Et2, MeEt, MenBu, or MenHex, by
AA [28] and LP-CVD methods [29] and also from xanthate compounds of the type [Ni
i
(S2COR)2], where R = Et or Pr by AACVD [30]. Recently, Alam et al. have used pyridine
adducts of nickel(II) xanthates as single-source precursors for the deposition of nickel
sulfide thin films by aerosol-assisted chemical vapor deposition (AACVD) [31].
Our team has focused on synthesis, characterization, crystal structures, biological
activities, and material applications of new thiourea derivatives and their metal complexes
[32–36]. In this manuscript, two acylthiourea derivatives, N-(diethylcarbamothioyl)-4-
nitrobenzamide (1a) and N-(di-n-propylcarbamothioyl)-4-nitrobenzamide (1b), and their Ni
(II) complexes were synthesized, characterized by spectroscopic techniques and crystal
structures of both complexes were determined by X-ray crystallography. In addition, these
metal complexes have been used as single-source precursors for deposition of nickel
sulfide semiconducting nanostructured thin films by AACVD.
2. Experimental
2.1. Materials and reagents
Analytical grade 4-nitrobenzoyl chloride (P98.0%), dipropylamine (99%), diethylamine
(P98%), sodium thiocyanate (99%), nickel(II) acetate tetrahydrate (99%), and tetrabutyl-
ammonium bromide (TBAB) (P98%) were purchased from Sigma–Aldrich. Analytical
grade solvents such as tetrahydrofuran (THF), toluene, acetonitrile, n-hexane, dichloro-
methane, ethanol, methanol, chloroform, ethyl acetate, and others were purchased from
Sigma–Aldrich and Riedel-de Haën (Germany), whereas ethanol and acetone were dried
using standard procedures [37]. All manipulations were carried out in air except the
AACVD.

2790
Nickel sulfide thin films
2.2. Physical measurements
Elemental analysis was carried out by the University of Manchester micro-analytical labo-
1
ratory. The H NMR was recorded in CDCl3 solvent on Bruker 400 MHz spectrophotome-
ters using tetramethylsilane as an internal reference. All the complexes were studied by
thermogravimetry in an inert atmosphere, at sample heating rate of 283 K/min, with a
DuPont 2000 ATG. Infrared spectra were recorded on a Specac single reflectance ATR
instrument (4000–400 cmÀ1, resolution 4 cmÀ1). Mass spectra of complexes (MS-APCl)
were recorded on a Micromass Platform II instrument. Melting points were recorded on
the Barloworld SMP10 Melting Point Apparatus. Deposited thin films of nickel sulfide
were carbon coated using Edward’s E306A coating system before carrying out SEM and
EDX analysis. SEM analysis was carried out using a Philips XL 30FEG and EDX was
carried out using a DX4 instrument. AFM analysis was carried out using a Veeco CP2
instrument. p-XRD studies were carried out on a Bruker SMART 1000 CCD diffractome-
ter using Cu-Kα radiation.
2.3. Synthesis of the ligands
A solution of p-nitrobenzoyl chloride 1.85 gm (0.01 M) in anhydrous acetone (80 mL) and
TBAB0.678 gm (0.3 M%) in acetone was added dropwise to a suspension of sodium thio-
cyanate 0.81 gm (0.01 M) in acetone (50 mL) and the reaction mixture was refluxed for
45 min. After cooling to room temperature, a solution of diethylamine 0.73 gm (0.01 M) or
di-n-propylamine 0.101 gm (0.01 M) in acetone (25 mL) was added and the resulting mix-
ture refluxed for 2 h. The reaction mixture was poured into five times its volume of cold
water, whereupon the acylthiourea precipitated. The solid product was washed with water
and purified by re-crystallization from an ethanol-dichloromethane mixture (1 : 2) or ethyl
acetate.
2.3.1. N-(Diethylcarbamothioyl)-4-nitrobenzamide (1a). Yellow crystals. M.p.: 437–
439 K. Yield: 3.0 g (91%). IR (νmax/cmÀ1): 3282 (NH), 2942, 2855 (C–H), 1645(C=O),
1
1231 (C=S). H NMR (400 MHz, CDCl3) in δ (ppm): 8.43 (br s, 1H, CONH), 8.32 (d,
2Hmeta, p-nitrophenyl), 8.06 (d, 2Hortho, p-nitrophenyl), 4.07 (q, 2H, N–CH2), 3.59 (q, 2H,
N-CH2), 1.38 (t, 3H, –CH3), 1.30 (t, 3H, –CH3); 13C–NMR (300 MHz, CDCl3) in δ
(ppm): 178.9, 163.2, 141.5, 138.3, 129.2, 125.1, 49.1.7, 13.9, 12.1. Anal. Calcd for
C12H15N3O3S: C, 51.23; H, 5.37; N, 14.94; S, 11.40. Found: C, 51.89; H, 5.41; N, 14.82;
S, 11.42.
2.3.2. N-(Dipropylcarbamothioyl)-4-nitrobenzamide (1b). Pale yellow. M.p.: 389–
390 K. Yield: 3.2 g (88%). IR (νmax/cmÀ1): 3202 (NH), 2929, 2863 (C–H), 1681 (C=O),
1
1252 (C=S). H NMR (400 MHz, CDCl3) in δ (ppm) and J (Hz): 8.45 (s, 1H, CONH),
8.12 (d, 2Hmeta, J = 8.3 Hz, p-nitrophenyl), 7.35 (d, 2Hortho, J = 8.8 Hz, p-nitrophenyl), 3.82
(t, 2H, N–CH2), 3.53 (m, 2H, CH2), 1.81 (m, 2H, CH2), 1.60 (m, 2H, CH2), 0.98 (t, 3H,
CH3), 0.91 (t, 3H, CH3). Anal. Calcd for C14H19N3O3S: C, 54.35; H, 6.19; N, 13.58; S,
10.36. Found: C, 54.32; H, 6.35; N, 13.57; S, 10.37.

S. Saeed et al.
2791
2.4. Synthesis of the complexes
A solution of nickel acetate (0.005 M) in methanol (35 mL) was added dropwise to a
solution of the ligand in a 1 : 2 ratio with a small excess of ligand in ethanol (35 mL) at
room temperature, and the resulting mixture was stirred for 3 h. The reaction mixture was
filtered, washed with ethanol, and re-crystallized from THF/acetonitrile mixture (1 : 1).
2.4.1. Bis[N-(diethylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2a). Quantities used
were 2.81 g (0.01 M) ligand (1a) and 1.24 g (0.005 M) nickel acetate tetrahydrate in
ethanol. Golden crystals. Yield: 3.5 g (88%). IR (νmax/cmÀ1): 2929, 2852 (Ar–H), 1506
1
(C–O), 1532 (C–N), 1139 (C–S). H NMR (400 MHz, CDCl3) in δ (ppm) and J (Hz):
8.01 (d, 4H, Ar–H), 7.32 (d, 4H, Ar–H), 3.51 (m, 8H, N–CH2), 1.32 (t, 12H, –CH3). Anal.
Calcd for C24H28N6O6S2Ni: C, 46.54; H, 4.56; N, 13.57; S, 10.35; Ni, 9.48. Found: C,
46.23; H, 4.53; N, 13.50; S, 10.26; Ni, 9.95. Mass (MS-APCI) (major fragment, m/z): 619
[M+, C24H28N6O6S2Ni].
2.4.2. Bis[N-(di-n-propylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2b). Quantities
used were 3.09 g (0.01 M) ligand (1b) and 1.24 g (0.05 M) nickel acetate tetrahydrate in
ethanol. Dark brown. Yield: 3.6 g (85%). IR (νmax/cmÀ1): 2930, 2857(Ar–H), 1503 (C–O),
1
1535 (C–N), 1142 (C–S). H NMR (400 MHz, CDCl3) in δ (ppm) and J (Hz): 8.03 (d, 4H,
Ar–H), 7.37 (d, 4H, Ar–H), 3.73 (t, 8H, N–CH2), 1.70 (m, 8H, CH2), 0.90 (t, 12H, –CH3).
Anal. Calcd for C28H36N6O6S2Ni: C, 47.79; H, 5.37; N, 12.44; S, 9.49; Ni, 8.69. Found: C,
49.55; H, 5.34; N, 12.37; S, 9.46; Ni, 8.34. Mass (MS-APCI) (major fragment, m/z): 675
[M+, C28H36N6O6S2Ni].
2.5. X-ray structure determination
Single-crystal X-ray diffraction (XRD) data for both the nickel complexes (2a, 2b) were
collected using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) on a Bruker
SMART 1000 CCD diffractometer. The structures were solved by Patterson methods
DIRDIF-99 [38] and expanded using Fourier techniques. All non-H atoms were refined
anisotropically. The programs used for data collection and cell refinement were SMART
and SAINT v7.34A, respectively [39, 40]. The software used to solve and refine the struc-
tures was SHELXL97 [41].
2.6. Deposition of nickel sulfide thin films by AA-CVD
Experiments were carried out as described by us previously [42]. In a typical deposition,
0.25 g of the precursor was dissolved in 15 mL THF in a two-necked 100 mL round-bottom
flask with a gas inlet that allowed the carrier gas (argon) to pass into the solution to aid
the transport of the aerosol. This flask was connected to the reactor tube by a piece of
reinforced tubing. The argon flow rate was controlled by a Platon flow gauge. Seven soda
glass substrates (approx. 1 Â 2 cm) were placed inside the reactor tube, which is placed in
a CARBOLITE furnace. The precursor solution in a round-bottom flask was kept in a
water bath above the piezoelectric modulator of a PIFCO ultrasonic humidifier (Model No.
1077). The aerosol droplets of the precursor thus generated were transferred into the hot

2792
Nickel sulfide thin films
wall zone of the reactor by carrier gas. Both the solvent and the precursor were evaporated
and the precursor vapor reached the heated substrate surface where thermally induced reac-
tions and film deposition took place.
3. Results and discussion
The acylthiourea derivatives and their nickel complexes were synthesized according to
reported procedures [43–47] with minor modifications as presented in scheme 1. The use
of phase transfer catalyst (PTC) as a method of agitating a heterogeneous reaction system
O
Cl
O2N
NaSCN
TBAB
Dry acetone
O
S
C
N
Sec. amine
O2N
O
S
R'
NH
( 1a, b )
N
R
O2N
Ni (CH3COO)2.4H O
2
NO
2
O2N
O
S
O
S
N
N
N
N
Ni
R
R'
R
R'
( 2a, b )
R = R' = ethyl and propyl
Scheme 1. Preparation of 1a, b and their metal complexes (2a, b).

S. Saeed et al.
2793
is gaining recognition [48, 49]. In search of improving methods to prepare the target
acylthiourea by reacting isothiocyanates with nucleophiles, we have found that use of
TBAB as phase transfer catalyst can produce isothiocyanates in good yield. The reaction
proceeds via nucleophilic addition of the secondary amine to the isothiocyanate. We have
conducted our reaction using TBAB as PTC to synthesize the acylthiourea derivatives.
3.1. Spectroscopic characterization
Solid state IR spectra of acylthiourea derivatives and the metal complexes from 4000 to
400 cmÀ1 were compared and assigned on careful comparison. Tentative assignments are
Figure 1. (a) The molecular structure of bis[N-(diethylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2a). (b) Unit
cell diagram of 2a.

2794
Nickel sulfide thin films
made according to the literature [50]. N,N′-disubstituted thioureas behave both as mono-
dentate and bidentate ligands, depending upon the reaction conditions. The characteristic
bands of N,N′-disubstituted thioureas are (cmÀ1): 3202–3282 (NH), 2855–2942 Ph (CH),
1645–1681 (C=O), and 1231–1252 (C=S), and there is a slight shift of (C=O) and (C=S)
groups stretching frequencies due to coordination of the ligands to nickel.
Acythioureas usually are bidentate to transition-metal ions through the acyl oxygen and
sulfur [43, 51–53]. FT-IR spectra of the complexes show significant changes when
Figure 2. (a) The molecular structure of bis[1-(4-nitrobenzoyl)-3,3-dipropylthiourea]nickel(II) (2b). (b) Packing
diagram of 2b.

S. Saeed et al.
2795
compared with FT-IR spectra of the corresponding ligands. The IR spectra of complexes
show absorption bands at υmax/cmÀ1: 2852–2929 Ph (CH), 1503–1506 (C–O), 1531–1575
(C–N), and 1139–1142 (C–S). The most striking changes are the N–H stretching frequency
at ꢀ3200 cmÀ1 in the free ligands disappears, in agreement with both ligand and complex
structure and the complexation reaction, indicating loss of proton originally bonded to
nitrogen of the (NH–CO) amide. Another striking change is observed for the carbonyl
stretching vibrations. The vibrational frequencies due to carbonyl (1645–1681 cmÀ1) in the
free ligands shift to lower frequencies upon complexation, confirming ligands are coordi-
nated to nickel(II) through oxygen and sulfur [54–57]. A comparative absorption pattern
of the complexes with the values of the free ligands demonstrates that the coordination of
acylthiourea ligands to nickel has a significant effect on υ(NH), υ(CO), and υ(CS)
frequencies.
1H NMR data for N,N′-disubstituted thioureas show that the NH resonates considerably
downfield from other resonances in the spectra. The proton chemical shifts are 8.43–8.45
for free NH protons and aromatic protons between 7.35 and 8.32 ppm. It has also been
observed that coordinating or highly polar solvents like DMSO-D6 have profound effect
on the free NH chemical shift and appear more downfield as compared with C6D6, CDCl3,
and CD2Cl2. This shift can be attributed to hydrogen bonding between NH and sulfoxide
1
(S=O). H NMR data for the metal complexes describe the existence of aromatic protons
at 7.32–8.01 ppm as reported earlier [58, 59]. Resonances due to NH of CONH moiety in
the ligands completely disappear in both 2a and 2b. This indicates loss of the proton origi-
nally bonded to nitrogen of (NH–CO) amide in the ligands and confirms the formation of
Table 1. Crystal data and structure refinement for 2a and 2b.
2a
2b
CCDC
879,351
879,353
Empirical formula
Formula weight
Crystal size
C24H28N6NiO6S2
619.35
C28H36N6NiO6S2
675.46
0.50 Â 0.35 Â 0.12 mm
0.35 Â 0.32 Â 0.18 mm
Temperature
299 K
300 K
Wavelength
Crystal system
Space group
0.71073 Å
Monoclinic
P21/c
a = 13.2407(13) Å
b = 14.8611(14) Å
c = 14.2608(14) Å
β = 91.928(1)°
0.71073 Å
Triclinic
Pī
Unit cell dimensions
a = 8.9483(8) Å
b = 13.3915(12) Å
c = 14.9970(13)Å
α = 65.229(1)°
β = 87.987(1)°
γ = 79.441(1)°
1602.4(2) Å3
1.400 Mg mÀ3
2.6–25.0°
Volume
2804.5(5) Å3
1.467 Mg mÀ3
2.7–25.0°
0.6646, 0.9007
15,272
Density (calculated)
Theta range of data collection
Max. and min. transmission
No. of reflections measured
No. of independent reflections
F (0 0 0)
0.7707, 0.8716
8906
5515
4924
1288
708
Refinement method
Z
Least-squares matrix on F2
4
Least-squares matrix on F2
2
R indices (all data)
Goodness-of-fit on F2
(Δ/ρ)max
0.0674
0.0460
1.05
1.04
0.74 e ÅÀ3
À0.86 e ÅÀ3
0.69 e ÅÀ3
À0.48 e ÅÀ3
(Δ/ρ)min

2796
Nickel sulfide thin films
nickel complexes. Thus, all the characteristic chemical shifts were identified by their inten-
sity and multiplicity patterns.
3.2. Single-crystal X-ray crystallography
The molecular structures of bis[N-(diethylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2a)
and bis[N-(di-n-propylcarbamothioyl)-4-nitrobenzamide]nickel(II) (2b) with their packing
Table 2. Selected bond lengths (Å) and angles (°) for 2a and 2b.
2a
2b
Ni1–S2
Ni1–S1
S1–C8
2.1331(10)
2.1439(10)
1.727(3)
Ni1–O4
Ni1–O1
Ni1–S2
1.854(17)
1.859(17)
2.136(8)
S2–C20
O1–C1
O4–C13
O4–Ni1–S2
O1–Ni1–S2
O4–Ni1–S1
O1–Ni1–S1
S2–Ni1–S1
1.739(4)
1.273(4)
1.273(4)
94.90(8)
178.52(8)
178.16(7)
94.43(7)
Ni1–O4
Ni1–O1
Ni1–O4
O4–Ni1–O1
O4–Ni1–S2
O1–Ni1–S2
O4–Ni1–S1
O1–Ni1–S1
1.854(17)
1.859(17)
1.854(17)
84.42(7)
94.57(6)
176.16(7)
174.64(8)
94.98(6)
86.91(4)
Table 3. Thermogravimetric analysis of 2a and 2b.
2a
2b
1st stage decomposition temperature range (K)
2nd stage decomposition temperature range (K)
Maximum degradation temperature range (K)
Weight loss at 1st stage decomposition (%)
Weight loss at 2nd stage decomposition (%)
Residual weight at 873 K (%)
506–598
601–848
553–593
61
17
18.64
511–802
–
553–603
77
–
18.18
120
100
80
60
x
x
40
20
x
2 0 0
20
30
40
50
60
70
80
2-Theta-Scale (deg)
Figure 3. XRD pattern of the nickel sulfide thin film obtained from 2a.

S. Saeed et al.
2797
diagrams are shown in figures 1 and 2, respectively; crystal data and refinement and
selected bond lengths and angles are listed in tables 1 and 2, respectively. In both of these
structures, the nickels are coordinated to two N-(di-R-carbamothioyl)-4-nitrobenzamide
(R = ethyl and n-propyl) ligands in cis-configuration. Nickels are in slightly distorted
square planar geometry coordinated by two oxygens and two sulfurs forming cis-[NiL2].
The angle between the planes (Ni, S1, O1) and (Ni, S2, O4) is 0.67(1)° for 2a and 6.21
(1)° for 2b. There is no significant difference between Ni–S bonds, 2.1331(10)-2.1439(10)
Å in both complexes. The Ni–O bonds are 1.852(2)–1.8591(17) Å. The bond lengths are
also comparable with those of square planar nickel(II)-β-thioxoketonates [8, 59–61].
The C–S, 1.720(3)–1.740(3) Å, and C–O, 1.265(3)–1.273(4) Å, bonds are longer than
the free ligand (1a) C=S (1.6632(14) Å) and C=O (1.2228(17) Å) bonds. However, C–N
bonds in the complexes, 1.308(4)–1.351(3) Å, were shorter than in the free ligand (1.3423
(17)–1.43431(16) Å). Lengthening of C–S and C–O bonds and shortening of C–N bonds
Figure 4. (a) SEM image of nickel sulfide thin film deposited from 2a at 723 K, (b) AFM image in 3D view of
film, and (c) shows average roughness and Rms roughness of thin film deposited at 723 K.

2798
Nickel sulfide thin films
suggest delocalization of the π-electrons over the chelate rings. The chelate rings are
almost planar, with maximum deviation from the mean plane less than 0.156(1) Å. The
dihedral angles between the chelate rings are 5.9(1)° for 2a and 7.3(1)° for 2b. Both com-
plexes also show short interchelate distances between S1 and S2, 2.942(4) Å for 2a and
2.926(4) Å for 2b, which are also within the usual S–S interchelate distance of analogous
square planar nickel(II)-β-thioxoketonates (2.85(1)–2.95(1) Å). Unlike analogs reported ear-
lier [60], both Ni complexes are not stacked into dimers, and the NiÁ Á ÁNi distances in both
complexes are > 6.30(1) Å. No close NiÁ Á ÁNi interactions were observed.
3.3. Thermal decomposition studies and characterization of thin films deposited from
single-source precursors
Thermal behavior of 2a and 2b has been examined by TGA, performed under an inert
atmosphere of flowing nitrogen (20 mL minÀ1) and a heating rate of 283 K/min. Thermal
decomposition data of complexes are given in table 3. TGA of 2a shows two-step decom-
position with a rapid weight loss between 406 and 598 K and the second step between 601
and 848 K. The major part of the complex degraded sharply at 553–593 K leaving the
approximate residual amount of 18.63%, close to the accumulative mass of decomposed
product NiS (Calcd 19.04%). TGA of 2b shows single-step decomposition of the complex
starts at 511 K and accomplished by 802 K. The major part of the complex degraded shar-
ply at 553–603 K leaving the approximate residual weight of 21.31%, close to the accumu-
lative mass of decomposed product NiS (Calcd 18.18%).
Thin films of nickel sulfide were prepared as described in the experimental section and
were studied and characterized by XRD, SEM, energy dispersion X-ray analysis (EDXA),
and AFM. The XRD pattern of as deposited film from 2a at 723 K is shown in figure 3.
At 723 K, the XRD pattern from this film shows that there are two phases of nickel sul-
fide. The diffraction pattern of the dominant phase is nickel sulfide in hexagonal (NiS1.19
)
with major diffraction peaks of (1 0 0), (1 0 1), (1 0 2), (11 0), and (2 0 2) planes (ICDD:
002-1277). The second phase is orthorhombic nonanickeloctasulfide (Ni8S9). The peaks of
30
20
10
0
20
30
40
50
60
70
2-Theta-Scale (deg)
Figure 5. p-XRD pattern of the nickel sulfide thin films obtained from 2b by AACVD.

S. Saeed et al.
2799
the second phase are shown with “x”. The SEM image of the film (figure 4(a)) shows that
the film morphology is porous structure formed by the network of interlinked or agglomer-
ated NiS crystals. EDX analysis of the film shows the composition Ni : S ratio:
61.67 : 44.57. The AFM image of the film (figure 4(b)) shows the growth of closely
packed crystallites onto a glass substrate with an average roughness of 12.0 nm (figure 4
(c)). The XRD pattern of as deposited film from 2b at 723 K is shown in figure 5. At
723 K, the XRD pattern from this film shows diffractions of hexagonal Ni17S18 in the
space group P3121 (152) with major diffraction peaks of (0 2 4), (0 3 3), (3 0 6), and (3 3 0)
planes (ICDD: 007-1010). The SEM image of the nickel sulfide thin film (figure 6(a))
shows compact and smooth film morphology with homogeneously dispersed particles. The
particles with irregular appearance have good orientation and clearly well-defined grain
boundaries. The EDXA of film indicates the composition as Ni : S ratio: 64.67 : 47.57. The
AFM image of the film (figure 6(b)) shows the growth of closely packed crystallites onto
a glass substrate with an average roughness of 12.4 nm (figure 6(c)).
Figure 6. (a) SEM image of nickel sulfide thin film deposited from 2b at 723 K, (b) AFM image in 3D view of
film, and (c) shows average roughness and Rms roughness of thin film deposited at 723 K.

2800
Nickel sulfide thin films
4. Conclusions
Nickel(II) complexes of thiourea ligands, N-(diethylcarbamothioyl)-4-nitrobenzamide (1a)
and N-(dipropylcarbamothioyl)-4-nitrobenzamide (1b), have been synthesized and the
structures of the complexes determined by single-crystal X-ray crystallography. AACVD
from 2a and 2b deposited nickel sulfide thin films at 450 °C. AFM studies showed the
average roughness of the deposited films as 12 nm.
Supplementary material
Crystallographic data for the structure reported in this article have been deposited with
Cambridge Crystallographic Data Center, CCDC 879,351 (2a) and 879,353 (2b). Copies
of this information may be obtained free of charge from the Director, CCDC, 12 Union
Road, Cambridge, CBZ IEZ, UK. Facsimile 44 01223 336 033, E-mail: deposit@ccdc.
cam.ac.uk or www: http//www.ccdc.com.ac.uk/deposit.
Acknowledgments
S. Saeed would like to acknowledge the HEC, Government of Pakistan for financial support
and also would like to thank The University of Manchester for providing the facilities for
this work.
References
[1] K. Ramasamy, M.A. Malik, P. O’Brien. Chem. Commun., 48, 5703 (2012).
[2] A. Abdelhady, K. Ramasamy, M.A. Malik, P. O’Brien. Mater. Lett., 99, 138 (2013).
[3] N. Boadi, M.A. Malik, J.A.M. Awudza, P. O’Brien. Dalton Trans., 10497 (2012).
[4] J. Akhtar, M. Akhtar, M.A. Malik, P. O’Brien, J. Raftery. J. Am. Chem. Soc., 134, 2485 (2012).
[5] K. Ramasamy, V.L. Kuznetsov, K. Gopal, M.A. Malik, J. Raftery, P.P. Edwards, P. O’Brien. Chem. Mater.,
25, 266 (2013); Doi: 10.1021/cm301660n.
[6] M. Shahid, M. Hamid, A. Tahir, M. Mazhar, M.A. Malik, M. Helliwell. Ind. Eng. Chem. Res., 51, 16361
(2012).
[7] K.A. Wahab, M.A. Malik, P. O’Brien, R. Winpenny, F. Tuna. Dalton Trans., 196 (2013).
[8] R.A. Baily, K.L. Rothaupt, R.K. Kullnig. Inorg. Chim. Acta, 147, 233 (1988).
[9] W. Bensch, M. Schuster. Z. Anorg. Allg. Chem., 611, 99 (1992).
[10] D.J. Che, G. Li, X.L. Yao, Q.J. Wu, W.L. Wang, Y. Zhu. J. Organomet. Chem., 584, 190 (1999).
[11] G. Kemp, A. Roodt, W. Purcell, K.R. Koch. J. Chem. Soc., Dalton Trans., 4481 (1997).
[12] G. Binzet, U. Flörke, N. Külcü, H. Arslan. J. Coord. Chem., 62, 3454 (2009).
[13] A. Molter, F. Mohr. Coord. Chem. Rev., 254, 19 (2010).
[14] N. Gunasekaran, P. Ramesh, M.N.G. Ponnuswamy, R. Karvembu. Dalton Trans., 12519 (2011).
[15] R. Richter, J. Sieler, L. Beyer, O. Lindqvist, L. Andersen. Z. Anorg. Allg. Chem., 522, 171 (1985).
[16] Y.F. Yuan, J.T. Wang, M.C. Gimeno, A. Laguna, P.G. Jones. Inorg. Chim. Acta, 324, 309 (2001).
[17] G. Kullerud, R.A. Yund. J. Petrol., 3, 126 (1962).
[18] M.V. Swain. J. Mater. Sci., 16, 151 (1981).
[19] J.C. Barry, S. Ford. J. Mater. Sci., 36, 3721 (2001).
[20] S.D. Sartale, C.D. Lokhande. Mater. Chem. Phys., 72, 101 (2001).
[21] M. Sharon, G. Tamizhmani, C. Levy-Clement, J. Rioux. Sol. Cells, 26, 303 (1989).
[22] Z. Zainal, N. Saravanan, H.L. Mien. J. Mater. Sci. Mater. Electron, 16, 111 (2005).
[23] S. Licht, G. Hodes, R. Tenne, J. Manassen. Nature, 326, 863 (1987).
[24] S.T. Oyama. J. Catal., 216, 343 (2003).
[25] R.S. Mane, C.D. Lokhande. Mater. Chem. Phys., 65, 1 (2000).
[26] J. Cheon, D.S. Talaga, J.I. Zink. Chem. Mater., 9, 1208 (1997).

S. Saeed et al.
2801
[27] R. Nomura, H. Hayata. Trans. Mater. Res. Soc. Japan, 26, 1283 (2001).
[28] P. O’Brien, J. Waters. Chem. Vap. Deposition, 12, 620 (2006).
[29] P. O’Brien, J.H. Park, J. Waters. Thin Solid Films, 431–432, 502 (2003).
[30] P.L. Musetha, N. Revaprasadu, M.A. Malik, P. O’Brien. Mater. Res. Soc. Symp. Proc., 879E, Z7.4 (2005).
[31] N. Alam, M.S. Hill, G. Kociok-Kohn, M. Zeller, M. Mazhar, K.C. Molloy. Chem. Mater., 20, 6157 (2008).
[32] S. Saeed, N. Rashid, P.G. Jones, A. Tahir. J. Heterocycl. Chem., 48, 74 (2011).
[33] S. Saeed, N. Rashid, R. Hussain, P.G. Jones. Eur. J. Chem., 2, 77 (2011).
[34] S. Saeed, N. Rashid, P.G. Jones, M. Ali, R. Hussain. Eur. J. Med. Chem., 45, 1323 (2010).
[35] S. Saeed, N. Rashid, P.G. Jones, R. Hussain, M.H. Bhatti. Cent. Eur. J. Chem., 8, 550 (2010).
[36] S. Saeed, W.-T. Wong. J. Heterocycl. Chem., 49, 580 (2012).
[37] D.D. Perrin, W.L.F. Armarego, D.R. Perrin. Purification of Laboratory Chemicals, 3rd Edn, Pergamon Press,
Oxford (1988).
[38] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, R. de Gelder, R. Israel, J.M.M. Smits. The DIR-
DIF99 Program System, Technical Report of the Crystallography Laboratory, University of Nijmegen, The
Netherlands (1999).
[39] Bruker AXS Inc. SMART (Version 5.059), Bruker AXS Inc., Madison, Wisconsin, USA (1998).
[40] Bruker AXS Inc. SAINT, (Version 7.34A), Bruker AXS Inc., Madison, Wisconsin, USA (2006).
[41] G.M. Sheldrick. SHELX, SHELXL97 SHELXS97 program. SHELX Acta Cryst., E64, 112 (2008).
[42] A. Panneerselvam, M.A. Malik, P. O’Brien, M. Helliwell. Chem. Vap. Deposition, 15, 57 (2009).
[43] G.M.A. El-Reash, F.I. Taha, G. Badr. Transition Met. Chem., 15, 116 (1990).
[44] D.S. Mansuroglu, H. Arslan, U. Flörke, N. Kulcu. J. Coord. Chem., 61, 3134 (2008).
[45] Y.-M. Zhang, H.-X. Pang, C. Cao, T.-B. Wei. J. Coord. Chem., 61, 1663 (2008).
[46] H. Arslan, U. Flörke, N. Külcü, M.F. Emen. J. Coord. Chem., 59, 223 (2006).
[47] G. Binzet, H. Arslan, U. Flörke, N. Külcü, N. Duran. J. Coord. Chem., 59, 1395 (2006).
[48] S.-Y. Ke, S.-J. Xue. ARKIVOC, x, 63 (2006).
[49] T.B. Wei, J.C. Chen, X.C. Wang. Synth. Commun., 26, 1147 (1996).
[50] D. Fregona, L. Giovagnini, L. Ronconi, C. Marzano, A. Trevisan, S. Sitran, B. Biondi, F. Bordin. J. Inorg.
Biochem., 93, 181 (2003).
[51] D.J. Che, X.L. Yao, G. Li, Y.H. Li. J. Chem. Soc., Dalton Trans., 1853 (1998).
[52] R. Richter, L. Beyer, J. Kaiser. Z. Anorg. Allg. Chem., 461, 67 (1980).
[53] L. Beyer, E. Hoyer, J. Liebscher, H. Hartmann. Z. Chem., 21, 81 (1980).
[54] A. Irving, K.R. Koch, M. Matoetoe. Inorg. Chim. Acta, 206, 193 (1993).
[55] K.R. Koch, C. Sacht, S. Bourne. Inorg. Chim. Acta, 232, 109 (1995).
[56] M. Mikami, I. Nakagawa, T. Shimanouch. Spectrochim. Acta, 23A, 1037 (1967).
[57] S. Saeed, N. Rashid, M. Ali, R. Hussain. Eur. J. Chem., 3, 200 (2010).
[58] K. Nakamoto. Infrared and Raman Spectra of Inorganic and Coordination Compounds, 4th Edn, Wiley,
New York (1986).
[59] H. Arslan, N. Külcü, U. Flörke. Transition Met. Chem., 28, 816 (2003).
[60] (a) P. Knuuttila, H. Knuuttila, H. Hennig, L. Beyer. Acta Chem. Scand., A36, 541 (1982); (b) R. del Campo,
J.J. Criado, E. García, M.R. Hermosa, A. Jiménez-Sánchez, J.L. Manzano, E. Monte, E. Rodríguez-Fernán-
dez, F. Sanz. J. Inorg. Biochem., 89, 74 (2002).
[61] H. Arslan, U. Florke, N. Külcü, E. Kayhan. Turk. J. Chem., 30, 429 (2006).