N, N -Disubstituted- N ′-acylthioureas as modular ligands for deposition of transition metal sulfides

Article abstract of DOI:10.1039/c7dt04860b

First row transition metal complexes (Ni, Co, Cu, Zn) with N,N-disubstituted-N′-acylthiourea ligands have been synthesized and characterized. Bis(N,N-diisopropyl-N′-cinnamoylthiourea)nickel was found to have the lowest onset temperature for thermal decomp

Full text of DOI:10.1039/c7dt04860b

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10.1039/C7DT04860B.
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ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
framework
a Zr-metal–organic
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N,N‐disubstituted‐N’‐acylthioureas as modular ligands for
deposition of transition metal sulfides
Received 00th January 20xx,
Accepted 00th January 20xx
Zahra Ali,a,b† Nathaniel E. Richey,a,† Duane C. Bock,a Khalil A. Abboud,a Javeed Akhtar,c Muhammad
Sher,b and Lisa McElwee‐Whitea,*
DOI: 10.1039/x0xx00000x
First row transition metal complexes (Ni, Co, Cu, Zn) with N,N‐disubstituted‐N’‐acylthiourea ligands have
been synthesized and characterized. Bis(N,N‐diisopropyl‐N’‐cinnamoylthiourea)nickel was found to have
the lowest onset temperature for thermal decomposition. Thin film deposition of Ni, Co, and Zn sulfides
by Aerosol Assisted Chemical Vapor Deposition from their respective N,N‐diisopropyl‐N’‐
cinnamoylthiourea complexes at 350 °C has been demonstrated.
www.rsc.org/
allows exploration of ligand chemistry that could not be used
in conventional CVD. Study of new ligands can provide a
means to tune the stoichiometry of the deposited material,
Introduction
Transition metal sulfides are
a
promising class of
increase atmospheric stability, and control the decomposition
semiconductors that show potential in a wide range of energy
and photonic related applications.1, 2 The materials properties
of the metal sulfide are important when considering
appropriate applications. For example, crystalline materials are
typically better for photonic applications,3 while amorphous
metal sulfides are promising for their use in lithium ion
batteries and as electrocatalysts.4, 5 In attempts to control the
properties of the materials, a multitude of strategies have
been employed in their synthesis. Among the techniques that
have been explored are variants of solvothermal processes and
chemical vapor deposition (CVD).6 For these methods, single
source precursors (SSP), in which both metal and sulfide
source are the same compound, are often able to produce the
metal sulfide at lower temperatures and with better control of
stoichiometry.7 Many of these single source precursors lack
the volatility to be used in conventional CVD, where
volatilization of neat precursor occurs in a bubbler. However,
this limitation can be overcome by using aerosol‐assisted
(AA)CVD, in which the precursor is dissolved in an appropriate
solvent and nebulized for transport to the substrate.8, 9 Since
volatility is not critical for AACVD precursors, the technique
temperature of the precursor.10
Currently, there are several ligands that are commonly
used in single source precursors for the AACVD of metal
sulfides. Metal thiolates have been used to deposit metal
sulfides at temperatures as low as 150 °C, however their
reactivity with air and water makes them difficult to work
with.11, 12 Dithiocarbamate ligands have been widely used in
deposition of a wide range of metal sulfides, such as iron,
copper, cobalt, nickel, zinc, molybdenum, tungsten, and tin.13‐
17
These complexes often do not require special handling,
however this comes at the price of higher deposition
temperatures, typically above 300 °C. Xanthate ligands have
similarly found use with a variety of metals and often
decompose at lower temperatures than their dithiocarbamate
analogues.18‐20 This lowered decomposition temperature of
the xanthate precursors comes from the Chugaev elimination
mechanism pathway by which these ligands can readily
decompose to their corresponding metal sulfide.21 Thiobiuret
and dithiobiuret complexes have also found use for the
deposition of a wide variety of late transition metal sulfides
and show no oxygen incorporation from the thiobiurets.22, 23
Several other ligands, such as thioureas and dithiophosphates,
have also been used though less commonly.24, 25
a. Department of Chemistry, University of Florida, Gainesville, Florida, 32611, USA.
Email: lmwhite@chem.ufl.edu
N,N‐disubstituted‐N’‐acylthiourea ligands have long been
b. Department of Chemistry, Allama Iqbal Open University, Islamabad, Pakistan.
c. Department of Chemistry, Polymers & Materials Synthesis Lab (PMS), Mirpur
University of Science & Technology (MUST), Alama Iqbal Road, Mirpur Azad
Kashmir Pakistan.
known to coordinate to many transition metals in a chelating
27
fashion similar to acetylacetonate.26,
Thermogravimetric
analysis (TGA) of several of these complexes is consistent with
thermal decomposition to the corresponding metal sulfide or
pure metal.28, 29 However, the complexes are not sufficiently
† These authors have contributed equally to this work.
Electronic Supplementary Information (ESI) available: Metal complex TGA and
DTG plots, PXRD of the deposits, and X‐ray crystallographic data. CCDC 1811086,
1811087, 1811088, 1811089. See DOI: 10.1039/x0xx00000x
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Scheme 1 Synthesis of N,N‐disubstituted‐N’‐acylthioureas and nickel complexes.
volatile for conventional CVD. There are a few reports of their
use in AACVD but these studies do not explore the effects on
decomposition temperature from varying the substituents on
the ligand.30, 31 Herein, we investigate the impact of the N‐
substituents, R and R’ on decomposition temperatures of Ni
complexes and demonstrate that these ligands can be used for
deposition of metal sulfides via AACVD.
Results and discussion
To investigate the effect of substituents, we synthesized and
compared four nickel complexes with ligands derived from two
acid chlorides, benzoyl and cinnamoyl chloride, and two
secondary amines, diphenyl‐ and diisopropylamine. The N,N‐
disubstituted‐N’‐acylthiourea ligands are readily synthesized in
a two‐step, one‐pot reaction by mixing the acid chloride and
sodium thiocyanate, followed by addition of the secondary
amine (Scheme 1).32 After purification by recrystallization from
an appropriate solvent mixture, the ligand was deprotonated
with a mild base and reacted with a metal salt to form the
respective ML2 or ML3 complex in good yield.33 The wide
range of commercially available acid chlorides and secondary
amines make this family of ligands highly modular.
The thermal behavior of these complexes was investigated
by both TGA and the first derivative of the TGA plot (DTG) (Fig.
1). From these data, it was observed that Ni(L3)2 (where R =
PhCH=CH, R′ = iPr) has the lowest decomposition temperature,
with mass loss occurring most rapidly at 223 °C. An increase of
approximately 25 °C in decomposition temperature is
observed for Ni(L1)2, in which R is phenyl. A similar increase of
approximately 25 °C in the decomposition temperature is
observed in comparison of Ni(L4)2 and Ni(L2)2. Varying R′ from
alkyl to aryl moiety also caused a significant increase in
Fig 1. (a) TGA and (b) DTG plots of the Ni(L1‐4)2 complexes.
though the ligand backbone remained unchanged. This shows
that decomposition temperature is directly correlated to the
substituents and that both R and R′ need to be carefully
considered when designing precursors based on this ligand
framework.
Fragmentation from mass spectrometry has previously
been used as a model for the gas phase decomposition of
precursors in CVD, though some care needs to be taken in
35
interpretation.34, Tandem mass spectrometry was used to
elucidate possible decomposition pathways of Ni(L3)2. In this
experiment the [M+H]+ ion was selectively trapped and
fragmentation was brought on by collision induced
dissociation until the parent peak was no longer visible (Fig S6,
ESI). A list of abundant ions observed in positive mode appears
in Table 1. The base peak is observed at m/z 510.93 and is
attributed to loss of diisopropylcyanamide ([M+H‐N(iPr)2CN]+).
The second largest peak is observed at m/z 507.07 and is
attributed to the loss of the cinnamoyl moiety ([M+H‐
PhCH=CHCO]+). In these two most abundant fragments the Ni‐
S bond is unaffected. This may be indicative of the preference
for these complexes to decompose to the metal sulfide.
decomposition temperature, with
a
difference of
approximately 45 °C between Ni(L1)2 and Ni(L2)2 as well as
between Ni(L3)2 and Ni(L4)2. This resulted in a total difference
Another
fragment
is
observed
for
the
of 70 °C in the decomposition of Ni(L3
) and Ni(L2)2, even
2
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Ni(L3)(diisopropylcyanamide) complex at m/z 473.17 (M+H‐
PhCH=CHCOSH]+) with a high relative abundance. If this
fragment were also formed during the thermal gas phase
reaction, the cyanamide would be expected to be labile,
similarly to what has been reported for acetonitrile adducts of
tungsten imido precursors.34 This secondary fragmentation
(loss of the cyanamide) would provide another route to the ion
observed at m/z 347.07 ([M+H‐HL3]+), corresponding to overall
loss of the L3 ligand. Loss of the HNR′2 moiety is also observed
in good abundance at m/z 535.87 ([M+H‐NH(iPr)2]+).
Table 1. Selected relative abundance of ion fragments from tandem mass spectrometry
of Ni(L3)2
m/z
Fragment
[M+H]+
Relative abundance
637.07
535.87
510.93
507.07
473.17
347.07
0
[M+H‐NH(iPr)2]+
[M+H‐N(iPr)2CN]+
[M+H‐PhCH=CHCO]+
[M+H‐PhCH=CHCOSH]+
[M+H‐HL3]+
44.3
100
92.1
91.0
55.7
Since among all nickel complexes, Ni(L3)2 had the lowest
decomposition temperature, L3 was selected for the synthesis
and study of several other ML2 and ML3 complexes (M = Ni, Zn,
Co, and Cu). The formation of all of the metal complexes could
be easily followed with IR spectroscopy during synthesis by
observing the disappearance of the amide N‐H and C=O
stretches of the free ligand. For the diamagnetic complexes,
Ni(L1‐4)2, Co(L3)3, and Zn(L3)2, the disappearance of the N‐H
The X‐ray crystal structures were determined for all M(L3
)
2
and M(L3
)
complexes. Ni(L3
)
showed a square planar
2
3
geometry with the sulfurs cis to one another and a S1‐Ni1‐S1A
bond angle of 83.83(2)° (Fig. 2a). The cis isomer has been
noted for other nickel complexes of N,N‐disubstituted‐N’‐
acylthioureas as well and by analogy, we assign the
proton in 1H
NMR
could also be
followed.
Fig 2. X‐ray crystallographic structures of (a) Ni(L3)2 (b) Cu(L3)2 (c) Co(L3)3 and (d) Zn(L3)2. Selected solvent molecules and disorder omitted for clarity.
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predominant isomer for Ni(L1)2, Ni(L2)2, and Ni(L4)2 as cis.30 material CoCl2 was oxidized during the synthesis of Co(L3)3,
The Cu(L3)2 crystal structure contained two copper centers, consistent with the diamagnetic 1H NMR spectrum. The crystal
one ordered and the other disordered, and two disordered structure shows Co(L3)3 as the facial isomer with S‐Co‐S angles
tetrahydrofuran molecules from the crystallization process ranging from 86.31(2) to 89.47(2)° (Fig. 2c). Zn(L3)2 crystallized
resulting in an overall formula of Cu(L3)2∙THF (Fig S2, ESI). in a distorted tetrahedral geometry indicated by the S1‐Zn‐S2
Cu(L3)2∙THF also showed square planar geometry, however the angle of 120.76(4)° (Fig. 2d). A noninteracting acetonitrile
coordination around copper was trans with respect to the molecule was also present in the asymmetric unit from the
sulfurs with a S1‐Cu1‐S1A angle of 180.0° (Fig. 2b). The crystallization process (Fig S4, ESI).
difference in cis and trans coordination around nickel and
While the coordination around the metal center varies
copper, respectively, has been observed previously for similar significantly among these complexes, several common
bis(thiobiuret) complexes.22 The cobalt(II) ion in the starting
Table 2. Selected crystal data and structure refinement data
Ni(L3)2
C32H42NiN4O2S2
Tetragonal
I‐4
Cu(L3)2∙THF
C36H50CuN4O3S2
Triclinic
Co(L3)3
C48H63CoN6O3S3
Monoclinic
P2I/c
Zn(L3)2∙NCCH3
C34H45ZnN3O2S2
Monoclinic
P2I/n
Formula
crystal system
Space group
a (Å)
P‐1
14.662(2)
14.662(2)
15.487(2)
90
10.5648(7)
11.9358(8)
15.2248(10)
79.6830(10)
72.2510(10)
84.0150(10)
1796.4(2)
1.173
9.6733(4)
26.7438(10)
18.9117(7)
90
13.8922(16)
7.4030(9)
34.250(4)
90
b (Å)
c (Å)
α (deg)
β (deg)
90
92.5405(9)
90
99.859(2)
90
γ (deg)
90
volume (Å3)
3329.2(11)
1.272
4887.7(3)
1.260
3470.4(7)
1.312
D
calc(Mg/m3)
total reflns
unique reflns
GOD of F2
36001
36766
114933
34093
5829
8897
18743
8616
1.029
1.025
1.016
0.829
Table 3. Selected bond distances (Å) for Ni(L3)2, Cu(L3)2∙THF, Co(L3)3, and Zn(L3)2∙NCCH3
Compound
Bond
M‐O bond lengths
M‐S bond lengths
Bond
Backbone C‐N lengths
Ni(L3)3
Cu(L3)2 ∙THFa
Ni1‐O1/S1
1.8719(9)
2.1424(4)
C1‐N1, C2‐N1
C1‐N1, C2‐N1
1.3283(16), 1.3441(16)
Cu1‐O1/S1
1.9093(13)
2.2709(4)
1.323(2), 1.354(2)
Co1‐O1/S1
Co1‐O21/S21
Co1‐O41/S41
1.9080(14)
1.9463(13)
1.9255(13)
2.2106(6)
2.2243(5)
2.2032(6)
C1‐N1, C2‐N1
C21‐N21, C22‐N21
C41‐N41, C42‐N41
1.335(3), 1.339(3)
1.337(2), 1.340(2)
1.329(3), 1.336(4)
Co(L3)3
Zn1‐O1/S1
Zn1‐O21/S21
1.968(3)
1.959(3)
2.2706(11)
2.3083(12)
C1‐N1, C2‐N1
C21‐N21, C22‐N21
1.324(5), 1.351(5)
1.313(5), 1.359(5)
Zn(L3)2∙NCCH3
aLengths from the ordered molecule within the unit cell.
Table 4. Selected bond distances (Å) for Ni(L3)2, Cu(L3)2∙THF, Co(L3)3, and Zn(L3)2∙NCCH3
Backbone C‐N‐C
Compound
Bonds
S‐M‐S angles
Bonds
Dihedral intersect
Dihedral angles
angles
Ni(L3)2
S1‐Ni1‐S2
83.83(2)
C1‐N1‐C2
C1‐N1‐C2
124.36(11)
N1
13.536(161)
Cu(L3)2∙THFa
S1‐Ni1‐S2
180.0
125.10(16)
N1
N1
N21
N41
32.825(221)
8.980(360)
34.806(211)
20.638(373)
S1‐Co1‐S42
S1‐Co1‐S42
S21‐Co1‐S42
89.47(2)
86.76(2)
89.31(2)
C1‐N1‐C2
C21‐N21‐C22
C1‐N1‐C2
125.53(17)
123.69(15)
126.3(2)
Co(L3)3
C1‐N1‐C2
C21‐N21‐C22
126.8(3)
126.4(3)
N1
N21
42.087 (0.413)
50.317(416)
Zn(L3)2
S1‐Zn1‐S2
121.76(4)
aAngles from the ordered molecule within the unit cell.
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characteristics are observed. As expected, the metal‐sulfide 13.536(161) and 8.980(360)°, respectively, but was larger in
bonds were significantly longer, approximately 0.3 Å on Zn(L3)2∙NCCH3 with angles of 42.087 (0.413) and 50.317(416)°.
average, than the metal‐oxide bonds due to the increased This dihedral angle also varied significantly for ligands on the
ionic radius of the sulfur. The bond lengths between the core same metal center and range between 8.980(360),
nitrogen (N1, N21, or N41) and the neighboring carbons 34.806(211), and 20.638(373)° on the Co(L3)3 complex. These
(C1/C2, C21/C22, or C41/C42) do not differ significantly, factors also cause the C‐N‐C angle in the ligand to open up to
indicating resonance delocalization through the ligand values from 123.69(15) to 126.8(3)°.
core.The ligand backbone was distorted from the planarity
expected for the free ligand. The dihedral angle between the complexes showed similar decomposition temperatures to
OCN and SCN planes (Fig S5, ESI), where N is the core nitrogen that of Ni(L3)2 (Fig S7, ESI). From the DTG trace, both Co(L3
TGA and DTG of the Cu(L3)2∙THF, Co(L3)3, and Zn(L3)
3
)
3
of the backbone (N1, N21, or N41) is less pronounced in and Cu(L3
) appear to undergo a multistep decomposition
2
Ni(L3
)
and one of the ligands in Co(L3
)
with angles of pathway. With these relatively low decomposition
temperatures, these compounds were precursor candidates
for the AACVD of their corresponding metal sulfide. Toluene
solutions of 0.65 mM were prepared for the Ni(L3)2, Co(L3)3,
and Zn(L3)2 complexes and depositions onto silicon substrates
were carried out at 350 °C. Cu(L3)2 was inadequately soluble
in toluene for these depositions and attempts to deposit
2
3
Cu(L3
) from a tetrahydrofuran solution at 350 °C were
2
unsuccessful, as indicated by absence of the metal sulfide on
the substrate by EDX or PXRD.
Deposition from Ni(L3)2 resulted in a mixture of individual
nanorods and thin sheets, which appeared to be fused from
several nanorods (Fig. 3a). Growth from Co(L3)3 resulted in the
deposition of platelets perpendicular to the substrate with an
underlying thin film (Fig. 3b). Zn(L3
) appeared to give the
2
most conformal film, with minimal surface features (Fig 3c).
EDX of these depositions resulted in an M:S ratio ranging from
1.0:0.84‐1.06 (Table 3). This is within the error for the metal
monosulfide deposition, however this is also within range of
the sulfur deficient Ni9S8 and Co9S8 phases, which are also
known. PXRD revealed mostly amorphous deposits, with only
ZnS showing some crystallinity by the presence of a small peak
at 28.5° which is indicative of the ZnS (111) reflection (Fig S8,
ESI). Several peaks from the silicon substrate were also
observed in the NiS and ZnS deposits. No increase in
crystallinity was observed after annealing at 650 °C for one
hour.
Table 5. Metal:sulfur ratios of the deposits
Precursor
Ni(L3)2
M:S ratio
1:0.90
Co(L3)3
Zn(L3)2
1.0:0.84
1.0:1.06
Conclusions
In summary, we have demonstrated that the thermal
decomposition temperatures of bis(N,N‐disubstituted‐N’‐
acylthiourea)nickel complexes vary with the substituents R
and R′. Ni(L3)2 (where R is PhCH=CH and R’ is isopropyl) had
the lowest decomposition temperature, with the most rapid
mass loss occurring at 223 °C. The related complexes Ni(L3)2,
Cu(L3)2, Co(L3)3, and Zn(L3)2 were all synthesized and found to
crystalize in the cis‐square planar, trans‐square planar, fac‐
octahedral, and distorted tetrahedral geometries respectively.
Fig 3. SEM images of the deposits grown at 350 °C from (a) Ni(L3)2, (b) Co(L3)3,
and (c) Zn(L3)2
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Ni(L3)2, Co(L3)3, and Zn(L3
) were found to deposit their While previously prepared, no spectroscopic data were
2
1
corresponding metal sulfide from AACVD at temperatures of reported.37 Yield: 7.0116 g, 78%. H NMR (300 MHz; DMSO‐
350 °C but attempted depositions from tetrahydrofuran
d6): = 10.32 ppm (s, 1H), 7.70 (m, 5H), 4.56 (broad, 1H), 4.30
solution of Cu(L3)2 were unsuccessful due its low solubility. (s, 1H), 1.36 (d, 12H). FTIR (neat): 3245 cm‐1 (m), 1786 cm‐1
These experiments demonstrate the viability of N,N‐ (m), 1650 cm‐1 (s), 1599 cm‐1 (m), 1581 cm‐1 (m), 1538 cm‐1
disubstituted‐N’‐acylthiourea ligands as sulfur sources in the (m).
AACVD of metal sulfides.
L2. Benzoyl chloride (3.95 mL) and diphenylamine (4.80 mL)
were used as the acyl chloride and diamine, respectively. The
Experimental
General information
compound was characterized by comparison to literature
data.38 Yield: 10.7371 g, 95%. 1H NMR (300 MHz; DMSO‐
d6):
= 11.18 ppm (s, 1H,), 7.40 (m, 15H). FTIR (neat): 3210 cm‐1 (m),
1690 cm‐1 (s), 1591 cm‐1 (m), 1501 cm‐1 (s).
Reagents were purchased from Sigma Aldrich or Fisher
Scientific; DMSO‐d6 was purchased from Cambridge Isotopes.
Nitrogen gas (99.999%) was purchased from AirGas. Toluene
was purified using an MBraun MB‐SP solvent purification
system and stored over activated 3 Å molecular sieves for at
least 48 h prior to experiments. Acetone was distilled over
CaSO4 and KMnO4 prior to use. All other reagents were used
as received. NMR spectra were recorded on a Varian Mercury
300 (300 MHz) spectrometer using residual protons from
deuterated solvents for reference. IR spectra were obtained
on a Bruker Vertex 80V equipped with an ATR diamond crystal
stage. Thermogravimetric analysis (TGA, TA Discovery5500)
was performed under N2 gas with a heating rate of 10
°C/minute. Mass spectrometry was performed on an Agilent
6220 ESI‐TOF with Agilent 1100 LC with electrospray ionization
(ESI) or direct analysis in real time (DART) ionization.
Elemental CHN analysis was performed by Robertson Microlit
laboratories, New Jersey. X‐Ray Intensity data were collected
at 100 K on a Bruker DUO diffractometer using MoKa radiation
(l = 0.71073 Å) and an APEXII CCD area detector.
L3. Cinnamoyl chloride (5.6644 g) and diisopropylamine (4.80
mL) were used as the acyl chloride and diamine, respectively.
1
Yield: 8.0972 g, 82%. H NMR (300 MHz; DMSO‐d6
:
= 10.13
ppm (s, 1H), 7.54 (m, 6H), 6.80 (d, 1H), 4.33 (broad, 1H), 1.39
(broad, 12H). FTIR (neat): 3237 cm‐1 (m), 1661 cm‐1 (m), 1626
cm‐1 (s), 1577 cm‐1 (w), 1526 cm‐1 (s).
L4. Cinnamoyl chloride (5.6644 g) and diphenylamine (4.80
mL) were used as the acyl chloride and diamine, respectively.
1
Yield: 10.6032 g, 87%. H NMR (300 MHz; DMSO‐
d
6): = 11.02
ppm (s, 1H), 7.32 (m, 16H), 6.67 (d, 1H). FTIR (neat): 3178 cm‐1
(m), 1704 cm‐1 (s), 1684 cm‐1 (w, sh), 1667 cm‐1 (s), 1634 cm‐1
(s), 1617 cm‐1 (s), 1589 cm‐1 (m), 1535 cm‐1 (m).
Metal complex synthesis
General Procedure for Nickel Complexes. This procedure was
adapted from a previously reported synthesis.39 Nickel
chloride hexahydrate (0.5940 g, 2.5 mmol) was dissolved in
(10 mL) of water and was added to a stirring solution of L1‐4
(5 mmol) in acetonitrile (35 mL). Sodium acetate (0.8200 g, 10
mmol) in water (10 mL) was then added, resulting in complex
precipitation that was filtered off and dried in vacuo.
Depositions were carried out using
a Blue Wave
Semiconductors CVD reactor with a Liquifog ultrasonic liquids
atomizer from Johnson Matthey Piezoproducts. The
crystallinities and morphologies were measured by X‐ray
diffraction (XRD, Panalytical X’pert Pro) and field emission
scanning electron microscopy (FESEM, FEI Nova NanoSEM
430). Elemental compositions of the deposits were
determined by energy‐dispersive X‐ray spectroscopy (FESEM,
FEI Nova NanoSEM 430).
Ni(L1)2. From 1.3220 g of L1, yield: 1.0245 g, 70%. The
compound was characterized by comparison to literature
data.39 1H‐NMR (300 MHz; DMSO‐
d6): = 8.18 (m, 4H), 7.61
(m, 6H), 4.85 (s, 2H), 4.10 (s, 2H), 1.55 (d, 12H), 1.34 (broad,
12H). FTIR (neat): 1587 cm‐1 (w) 1509 cm‐1 (m). MS (ESI) m/z
585.18 (M+H+). Elemental analysis: Calc. for C28H38N4O2S2Ni: C,
57.44; H, 6.54; N, 9.57; Found: C, 57.51; H, 6.60; N, 9.57%.
Ligand synthesis
General Procedure for Ligands L1, L2, L3 and L4. This
procedure was adapted from
a
previously reported
synthesis.36, 37 The acyl chloride (34 mmol) was stirred with
NaSCN (34 mmol) in dry acetone (25 mL) for 10 minutes, after
which the solution was milky white. The dialkyl or diaryl amine
(34 mmol) was dissolved in dry acetone (15 mL) and was then
added to the stirring solution, which turned yellow. The
solution was then added to 250 mL of ice cold water, at which
point the crude product precipitated. The crude product was
filtered, dried, and recrystallized from an acetonitrile:water
(3:1) mixture.
Ni(L2)2. From 1.6621 g of L2, yield: 1.1183 g, 62%. The
compound was characterized by comparison to literature
data.39 1H‐NMR (300 MHz; DMSO‐
d6): = 9.00 (m, 4H), 7.46
(m, 22H), 7.12 (m, 4H). FTIR (neat): 1588 cm‐1 (w), 1508 cm‐1
(s). MS (DART) m/z 721.12 (M+H+). Elemental analysis: Calc.
for C40H30N4O2S2Ni: C, 66.59; H, 4.19; N, 7.77. Found: C, 67.04;
H, 3.84; N, 7.58%.
Ni(L3)2. From 1.4522 g of L3, yield: 1.1165 g, 73%. X‐ray quality
crystals were obtained from recrystallization in acetonitrile.
L1. Benzoyl chloride (3.95 mL) and diisopropylamine (4.80 mL)
were used as the acyl chloride and diamine, respectively.
1H‐NMR (300 MHz; DMSO‐
d6): δ 7.63 (m, 6H), 7.42 (m, 6H),
7.00 (d, 2H), 4.85 (s, 2H), 3.95 (s, 2H), 1.49 (broad, 12H), 1.26
6 | J. Name., 2012, 00, 1‐3
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(broad, 12H). FTIR (neat): 1638 cm‐1 (m), 1577 cm‐1 (w), 1506
cm‐1 (m). MS (ESI) m/z 637.21 (M+H+). Elemental analysis:
Calc. for C32H42N4O2S2Ni: C, 60.29; H, 6.64; N, 8.79. Found: C,
60.29; H, 6.41; N, 8.72%.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
Ni(L4)2. From 1.7923 g of L4, yield: 1.2377 g, 64%.1H‐NMR
ZA acknowledges Higher Education Commission (HEC),
Pakistan for financial assistance. KAA wishes to acknowledge
the National Science Foundation and the University of Florida
for funding of the purchase of the X‐ray equipment. We thank
the UF Mass Spectrometry Research and Education Center,
supported by NIH S10 OD021758‐01A1, for mass spectrometry
data.
(300 MHz; DMSO‐d6): δ = 7.49 (m, 28H), 7.11 (m, 4H), 6.89 (m,
2H). FTIR (neat): 1629 cm‐1 (m), 1589 cm‐1 (w), 1576 cm‐1 (w),
1501 cm‐1 (s). MS (ESI) m/z 773.15 (M+H+). Elemental analysis:
Calc. for C44H34N4O2S2Ni: C, 68.32; H, 4.43; N, 7.24. Found: C,
68.22; H, 4.18; N, 7.14%.
Cu(L3)2∙THF. Same procedure as for Ni(L3)2, substituting the
nickel chloride with cupric nitrate trihydrate (0.6040 g, 2.5
mmol) and recrystallized from THF. Yield: 1.4111g, 79%. FTIR
(neat): 1636 cm‐1 (m), 1577 cm‐1 (w), 1501 cm‐1 (m, sh). MS
(ESI) m/z 642.21 ([M‐THF+H]+). Elemental analysis: Calc. for
C36H50N4O3S2Cu: C 60.52; H, 7.05; N, 7.84. Found: C, 60.41; H,
7.09; N, 7.78%.
Notes and references
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J. Name., 2013, 00, 1‐3 | 7
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8 | J. Name., 2012, 00, 1‐3
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Table of Contents Entry
Readily available N,N-disubstituted-N’-acylthiourea complexes are single source precursors for Aerosol Assisted
Chemical Vapor Deposition of metal sulfide thin films.