Comparative evolved gas analytical and structural study on trans-diammine-bis(nitrito)-palladium(II) and platinum(II) by TG/DTA-MS, TG-FTIR, and single crystal X-ray diffraction

Article abstract of DOI:10.1016/j.tca.2009.02.006

Detailed study on identification and thermal decomposition of solid title compounds 1 and 2 crystallized from the used aqueous ammonia solutions of Pd(NH₃)₂(NO₂)₂ and Pt(NH₃)₂(NO₂

Full text of DOI:10.1016/j.tca.2009.02.006

Thermochimica Acta 490 (2009) 51–59
Contents lists available at ScienceDirect
Thermochimica Acta
journal homepage: www.elsevier.com/locate/tca
Comparative evolved gas analytical and structural study on
trans-diammine-bis(nitrito)-palladium(II) and platinum(II)
by TG/DTA–MS, TG–FTIR, and single crystal X-ray diffraction
a,∗
b
b
c
c
a
János Madarász , Petra Bombicz , Czugler Mátyás , Ferenc Réti , Gábor Kiss , György Pokol
a
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, Budapest H-1521, Hungary
Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest H-1525, POB 17, Hungary
Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, Budapest H-1111, Hungary
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Detailed study on identification and thermal decomposition of solid title compounds 1 and 2 crystallized
from the used aqueous ammonia solutions of Pd(NH3)2(NO2)2 and Pt(NH3)2(NO2)2, has been carried
out. Beyond the composition of complexes 1 and 2, their trans square planar configuration have already
been recognized by reference IR spectra and powder XRD patterns, nevertheless their exact molecular
and crystal structure as of trans-Pd(NH3)2(NO2)2 (1, Pd-NN) and trans-Pt(NH3)2(NO2)2 (2, Pt-NN) has
been determined by single crystal X-ray diffraction (R = 0.0515 and 0.0341), respectively. Despite their
compositional and configuration analogy, they crystallize in different crystal systems and space groups.
The crystals of 1 (Pd-NN) are triclinic (space group No. 2, P-1, a = 5.003(1) Å, b = 5.419(1) Å, c = 6.317(1) Å,
Received 3 December 2008
Received in revised form 2 February 2009
Accepted 6 February 2009
Available online 21 February 2009
Keywords:
Evolved gas analysis (EGA)
Mass spectrometry (MS)
FTIR-spectroscopic gas cell
Simultaneous thermogravimetry (TG) and
differential thermal analysis (DTA)
Single crystal X-ray diffraction
Determination of molecular and crystal
structure
◦
◦
◦
˛
= 91.34(2) , ˇ= 111.890(10) , ꢀ= 100.380(10) ), while those of 2 (Pt-NN) are monoclinic (space group No.
◦
5, C2, a = 7.4235(16) Å, b = 9.130(2) Å, c = 4.4847(10) Å, ˇ= 99.405(7) ).
The pyrolytic processes of 1 and 2 (which might be sensitive to shock and heat) have been followed by
simultaneous thermogravimetric and differential thermal analysis (TG/DTA), while the evolved gaseous
species have been traced in situ by online coupled TG/DTA–EGA–MS and TG–EGA–FTIR instruments in
He and air. Pd and Pt powders, forming as final solid products in single step, are captured and checked by
TG and XRD. Whilst the unified evolved gas analyses report evolution of N2, H2O, NH3, N2O, NO, and NO2
CO sensors
Pt and Pd catalysts
gases as gaseous product components in the exothermic decomposition of both trans-Pd(NH3)2(NO2)2
◦
(
1) and trans-Pt(NH3)2(NO2)2 (2) starting from ca. 230 and 220 C, in sealed crucibles with a pinhole on
the top, respectively.
©
2009 Elsevier B.V. All rights reserved.
◦
1. Introduction
zation of SnO2 layers for CO gas has been observed at 90 C
[
1].
In order to get a deeper insight in to chemical mechanism of
This study has been directly initiated by the work of Kiss
et al. [1], who studied the CO sensitivity of SnO2 thick layer
sensors impregnated with Pt(NH ) (NO ) and Pd(NH ) (NO )
the sensitization process, we have tried to identify the active sens-
ing chemical species of residues obtainable from the impregnating
Pd or Pt solutions, on a higher mass scale and with other analytical
methods different from XPS. We could carry out a detailed study on
thermal decomposition of solid trans-Pd(NH ) (NO ) (1, Pd-NN)
3
2
2
2
3
2
2 2
depending on their fabrication temperature. The complexes had
◦
been decomposed by heat treatments in range of 150–350 C
in air, and the surface composition had achieved were eval-
uated by X-ray photoelectron spectroscopy (XPS) [1]. Basically
PtO and PdO was found to be present on the surface beyond
some Pt(OH)2 and some partially decomposed Pd complex,
respectively [1]. Despite these spurious XPS findings, start-
ing with commercially available aqueous ammonia solutions of
Pd(NH ) (NO ) and Pt(NH ) (NO ) , after impregnations and
3
2
2 2
and trans-Pt(NH ) (NO ) (2, Pt-NN), which actually firstly crystal-
3
2
2 2
lized from the applied commercial aqueous ammoniacal solutions.
Both solid and gaseous state analyses of the decomposition prod-
ucts have been performed by powder XRD and evolved gas analysis
(EGA), respectively.
The essentially violent thermal decomposition processes of solid
complexes 1 and 2 has been studied and followed by simultaneous
thermogravimetric (TG) and differential thermal analysis (TG/DTA)
in semi-sealed Al crucibles, while the evolved gaseous species
has been traced in situ by online coupled TG/DTA–EGA–MS and
TG–EGA–FTIR instruments in He and air, whilst the solid residues
3
2
2
2
3
2
2 2
◦
heat treatments between 150 and 350 C, a successful sensiti-
∗ Corresponding author. Tel.: +361 463 4047; fax: +361 463 3408.
E-mail address: madarasz@mail.bme.hu (J. Madarász).
0
040-6031/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.tca.2009.02.006

5
2
J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
Table 1
Crystal data, data collection and structure refinement of compounds trans-Pd(NH3)2(NO2)2 (1, Pd-NN) and trans-Pt(NH3)2(NO2)2 (2, Pt-NN).
1
trans-Pd(NH3)2(NO2)2
2 trans-Pt(NH3)2(NO2)2
Empirical formula
Formula weight
Temperature (K)
Radiation wave length, ꢁ(Å),
Crystal system
Space group
PdN4H6O4
232.49
293(2)
0.710730, (MoK()
Trilinic
P-1, No. 2
PtN4H6O4
321.17
295(2)
0.710730 (MoK()
Monoclinic
C2, No. 5
Unit cell dimensions
a (Å)
b (Å)
5.003(1)
5.419(1)
6.317(1)
91.34(2)
7.4235(16)
9.130(2)
4.4847(10)
90
99.405(7)
90
299.87(11)
2/0.5
3.557
c (Å)
◦
˛
( )
◦
ˇ( )
111.89(1)
◦
␥
( )
100.38(1)
155.54(5)
1/0.5
2.482
2.939
3
Volume (Å )
ꢀ
Z/Z
Density (calculated) [Mg m−3]
Absorption coefficient, ꢂ(mm−1)
F(0 0 0)
23.352
288
112
Crystal colour
Crystal description
Bright yellow
Block
Colourless
Block
Crystal size (mm)
Absorption correction
Max. and min. transmission
ꢃrange for data collection ( )
Index ranges
0.30 × 0.20 × 0.10
Semi-empirical (␺-scan)
1.000 and 0.505
3.49 ≤ ꢃ≤ 24.99
−10 ≤ h ≤ 10;
0.13 × 0.33 × 0.41
Numerical
1.000 and 0.8977
3.6 ≤ ꢃ≤ 27.5
−9 ≤ h ≤ 9;
−11 ≤ k ≤ 11;
−5 ≤ l ≤ 5
1706
0.932
673 [R(int) = 0.072]
673
673/0/45
1.13
◦
−
11 ≤ k ≤ 11;
13 ≤ l ≤ 13
−
Reflections collected
Completeness to 2ꢃ
Independent reflections
Reflections I > 2ꢄ(I)
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices (I > 2ꢄ(I))
R1
7134
0.998
3262 [R(int) = 0.0345]
2618
3262/0/46
1.510
0.0515
0.1002
0.0341
0.0788
R2
R indices (all data)
R1
0.0875
0.0341
R2
0.1235
0.0788
Extinction coefficient
Max. and mean shift/esd
Largest diff. peak and hole (e A−3)
0.097(8)
0.0053(7)
0.008, 0.001
0.99 and −2.86
0.000, 0.000
2.629 and −3.197
The weighting schemes applied for 1 and 2 respectively was 1. w = 1/[ꢄ (F02) + (0.0202P)2 + 0.3178P] where P = (F02 + 2Fc2)/3. and 2. w = 1/[ꢄ (F02) + (0.0563P)2 + 0.0P] where
2
2
P = (F0 + 2Fc2)/3.
2
Table 2
Comparison of the FTIR spectra segments in ref [11] and the present work.
Band positions (cm−1) for trans-Pd(NH3)2(NO2)2
−1
Band positions (cm ) for trans-Pt(NH3)2(NO2)2
In ref. [11]
375
In present work
In ref. [11]
In present work
1
1386
1327
1261
828
791
592
1365
1325
1282
828
–
1370
1334
1288
829
–
1325
1255
8
8
5
4
30
00
88
94
626
518
628
524
496
Table 3
Intermolecular interactions in the complexes of 1 (Pd-NN) and 2 (Pt-NN).
1
(Pd-NN)
d(D–H) (Å)
0.89
0.89
0.89
d(D–H) (Å)
0.89
0.89
0.89
0.89
0.89
d(H· · ·A) (Å)
2.15
2.21
d(D· · ·A) (Å)
(D–H· · ·A) (◦)
Symmetry operation
x,1 + y, z
1 + x,1 + y, z
1 − x,−y,1 − z
Symmetry operation
Intra
N1-H11· · ·O32
N1-H12· · ·O32
N1-H13· · ·O31
3.034(5)
3.085(5)
3.136(5)
d(D· · ·A) (Å)
2.89(4)
170
168
169
␺(D–H· · ·A) ( )
2.26
◦
2
(Pt-NN)
d(H· · ·A) (Å)
N1-H11· · ·O21
N1-H12· · ·O31
N1-H11· · ·O31
N1-H12· · ·O21
N1-H13· · ·O21
2.33
121
113
150
147
137
2.34
2.34
2.26
2.50
2.81(4)
3.14(3)
3.05(4)
3.21(4)
Intra
1/2 − x,−1/2 + y,1 − z
1/2 − x,1/2 + y,1 − z
1/2 − x,1/2 + y,−z

J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
53
Fig. 1. FTIR spectra of samples 1 (Pd-NN) and 2 (Pt-NN) in KBr.
are checked by XRD phase analysis. Especially a better understand-
ing of mechanism and dynamics of the gas evolution from these
solid complexes 1 and 2 which are probably sensitive also to shock,
seems to be essential during a scaling up of the sensor fabrication.
2. Experimental
2.1. Samples and methods
The samples 1 and 2 were crystallized at room temperature
by slow evaporation of the solvent then filtered from commer-
cially available precursor solutions of the Aldrich Chem. Co. with
PN 33,990-3 (‘Diamminedinitritopalladium(II) solution in dilute
ammonium hydroxide, Pd cc. 5%. Dry material may be shock
sensitive! Protect from light’!) and PN 33,988-1 (diammine dini-
tritoplatinum(II) 3.4 wt% solution in dilute ammonium hydroxide,
Light sensitive! Dry material may be shock sensitive!), which were
used as received.
FTIR spectra of solid samples 1 and 2 were measured by Excal-
ibur Series FTS 3000 (BioRad) FTIR spectrophotometer in KBr
(
4
with gentle powdering and suitable precautions) between 400 and
000 cm , meanwhile the XRD patterns of theirs and their solid
−
1
decomposition products obtained after the thermal runs from the
thermal balances were recorded on X’pert Pro MPD (PANalytical Bv,
The Netherlands) X-ray diffractometer using Cu K˛radiation with
Ni filter and X’celerator detector.
2.2. Structure determination and refinement by single crystal
X-ray diffraction of trans-Pd(NH ) (NO ) (1) and
3
2
2 2
trans-Pt(NH ) (NO ) (2)
Fig. 2. The complex of 1 (Pd-NN). (a) ORTEP diagram [7,8] at 50% probability level.
Half of the molecule is in the asymmetric unit. Atoms labeled with the extension
of “a” are symmetry generated. (b) The intermolecular interactions of a complex
molecule. All hydrogen bonds are the type of N–H· · ·O.
3
2
2 2
A bright yellow single crystal of 1 was mounted on glass fiber.
Cell parameters were determined by least-squares of the setting
◦
◦
angles of 25 reflections (18.37 ≤ ꢃ≤ 19.58 ). Intensity data with
ω–2ꢃscans were collected on an Enraf-Nonius CAD4 diffractometer
using graphite monochromated MoK␣ radiation. Data reductions
was carried out by program XCAD4 [2], while the empirical absorp-
A block type colourless crystal of 2 was mounted on a loop
with oil. Cell parameters were determined by least-squares of the
◦
◦
setting angles of all 1704 reflections (3.57 ≤ ꢃ≤ 27.45 ). Intensity
data were collected on a RAXIS-RAPID diffractometer using graphite
monochromated MoK␣ radiation. R(␴) = 0.0496]. Completeness to
2ꢃ= 1.000. Numerical absorption correction was applied.
tion corrections were done by MolEN [3]. The scan width was
◦
0
.61 + 0.82tg(ꢃ) in ω. Backgrounds were measured 1/2 the total
time of the peak scans. The intensities of three standard reflections
were monitored every 60 min. The intensities of the standard reflec-
tions indicated a crystal decay of 1%, the data were corrected for
The initial structure models were found by direct methods using
SHELXS97 [4], the anisotropic full-matrix least-squares structure
refinements on F2 were performed by SHELXL97 [5] for all non-
◦
decay, R(sigma) = 0.0359]. Completeness to 2ꢃ= 0.998 .

5
4
J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
Fig. 3. The complex of 2 (Pt-NN). (a) ORTEP diagram [7,8] at 50% probability level.
Half of the molecule is in the asymmetric unit. Atoms labeled with the extension of
“a” are symmetry generated. (b) The direction of the intermolecular interactions of
a complex molecule. All hydrogen bonds are the type of N–H· · ·O.
hydrogen atoms. The highest peak and deepest hole of the residual
electron density synthesis are around the heavy metal centers Pd
and Pt cations, respectively.
Hydrogen atomic positions of 1 were calculated from assumed
geometries, except H11 that was located in difference maps.
Hydrogen atomic positions of 2 were located on difference maps.
Hydrogen atoms were included in structure factor calculations but
they were not refined. The isotropic displacement parameters of
the hydrogen atoms were approximated from the U(eq) value of
Fig. 4. Simultaneous TG/DTG/DTA curves of (a) crystal 1 (trans-Pd(NH3)2(NO2)2)
and (b) 2 (trans-Pt(NH3)2(NO2)2), measured in situ by online coupled TG/DTA–MS
system. (He flow 110 mL/min, heating rate 10 C/min, in sealed Al crucibles with a
◦
pinhole on the top, initial masses 3.08 mg and 2.98, respectively).

J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
55
Fig. 5. Gas evolution curves of various of gaseous species, represented by their characteristic mass spectroscopic ion fragments, from (a) crystal 1 (trans-Pd(NH3)2(NO2)2)
◦
and (b) 2 (trans-Pt(NH3)2(NO2)2) in helium, as measured in situ by online coupled TG/DTA–EGA–MS system (He flow 110 mL/min, heating rate 10 C/min, initial mass 3.08 mg
and 2.98, respectively).

5
6
J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
Fig. 7. FTIR spectra of gaseous mixture observed in the air decomposition of 1 (trans-
◦
Pd(NH3)2(NO2)2) at around 255 C measured by the online TG–FTIR system (heating
◦
−1
rate 10 C min , 130 mL/min air flow, initial mass 3.19 mg).
◦
steal transfer line (l = 90 cm, d = 2 mm) kept at T = 180 C. FTIR
in
−
1
spectra (550–4000 cm ) were collected in every 30 s after accu-
mulation of 29 interferograms by a BioRad Excalibur Series FTS
3000 spectrometer using Win IR Pro 2.7 FTIR (BioRad) data col-
lection and evaluation software.
2.5. FTIR spectroscopic and mass spectrometric identification of
various gaseous species
The components of released gaseous mixtures were monitored
and identified mostly on the basis of their FTIR and MS reference
spectra available on world-wide web in the public domain spectral
libraries of NIST [9,10].
3. Results and discussion
Fig. 6. Gas evolution curves of various of gaseous species, represented by their
mass spectroscopic ion fragments, from (a) crystal (trans-Pd(NH3)2(NO2)2)
3.1. FTIR and XRD identification of solid samples 1 (Pd-NN) and 2
1
and (b) 2 (trans-Pt(NH3)2(NO2)2) in air, as measured in situ by online coupled
TG/DTA–EGA–MS system (He flow 110 mL/min, heating rate 10 C/min, initial mass
(Pt-NN) as trans-Pd(NH ) (NO ) and trans-Pt(NH ) (NO ) ,
respectively
3 2 2 2 3 2 2 2
◦
1.46 mg and 2.77, respectively).
FTIR spectra of samples 1 (Pd-NN) and 2 (Pt-NN) are shown
in Fig. 1. The FTIR-spectra of samples 1 (Pd-NN) and 2 (Pt-NN)
are similar and resembling to those of trans-Pd(NH ) (NO ) and
the atom they were bonded. Neutral atomic scattering factors were
taken from the International Tables for X-ray Crystallography, vol.
C [6].
Details of data collection and crystallographic data are presented
in Table 1.
3
2
2 2
trans-Pt(NH ) (NO ) , respectively, as far as could be compared in
3 2 2 2
−
1
the published wave number range of 400–1400 cm [11]. Detailed
comparison of the corresponding wave numbers to those of in ref.
11] are given in Table 2. In the range of 1500–1700 cm the sam-
−
1
[
2
.3. In situ EGA by coupled TG/DTA–MS
ple 1 (Pd-NN) shows only one sharp H–N–H bending vibration band
−
1
at 1647 cm , while sample 2 (Pt-NN) displays three sharp ones at
−
1
A simultaneous TG/DTA apparatus (STD 2960 Simultaneous
1655(s), 1600(w) and 1558(s) cm . It is probably due to the higher
complexity of hydrogen bond system in sample 2 (Pt-NN) compared
to that of sample 1 (Pd-NN) (see later).
◦
−1
,
DTA–TGA, TA Instruments Inc., USA), a heating rate of 10 C min
an air flow rate of 130 mL/min, sample sizes between 2.1 and
.8 mg, and sealed Al crucibles with a pinhole on the top were
used. The mixture of gaseous species could reach a ThermoStar GDS
00(Balzers Instruments)quadrupole mass spectrometer equipped
8
Powder XRD phase identification has confirmed that the XRD
pattern of samples 1 (Pd-NN) and 2 (Pt-NN) corroborates with that
of unspecified Pd(NH3)2(NO2)2 and trans-Pt(NH3)2(NO2)2 (PDF 00-
45-598 [12,13] and PDF 00-54-155 [12,14]), respectively. The latter
pattern is indexed erroneously in space group C2/m (No. 12).
The powder patterns of 1 and 2 reveal the structural differences
of the two complexes.
2
with Chaneltron detector, through a heated 100% methyl deacti-
vated fused silica capillary tubing kept at T = 200 C. Data collection
was carried out with QuadStar 422v60 software in multiple ion
detection mode (MID) monitoring 64 selected channels ranging
mostly between m/z 12 and 78. Measuring time was ca. 0.5 s for
one channel, resulting in time of measuring cycles of ca. 30 s.
◦
3.2. Molecular and crystal structure of trans-Pd(NH ) (NO ) 1
2 2,
3
2
(
Pd-NN) and trans-Pt(NH ) (NO ) 2 (Pt-NN)
3 2 2 2,
2.4. In situ EGA by coupled TG–FTIR
The molecular structure, conformation and the complex sys-
A TGA 2050 thermogravimetric analyzer (TA Instruments, USA)
with a heating rate of 10 C min , with air flow rate of 120 mL/min,
and an extra 20 mL/min air as a balance purge) and sample
size 1.8–6.5 mg of samples sealed Al crucibles with a pinhole
on the top were used. Gaseous species evolved from the sam-
ple were led to FTIR gas cell of a BioRad TGA/IR accessory unit
equipped with cooled DTGS detector through a heated stainless
tem of intermolecular interactions of 1 (Pd-NN) and 2 (Pt-NN)
were determined by single crystal X-ray diffraction. The complex
arrangements are square planar and the configurations are trans
around the heavy metal (Pd2+ or Pt ) cations surrounded by two
ammonia and two nitrite anion as ligands (Figs. 2 and 3). Although
the 1 (Pd-NN) and 2 (Pt-NN) are chemically analogue molecules and
their configuration is highly similar, their crystals are not isostruc-
◦
−1
(
2+

J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
57
Fig. 8. Evolution courses of gaseous species, from sample 1 (trans-Pd(NH3)2(NO2)2),. (by integration of IR-absorbance in their characteristic wave number regions observed
◦
in situ TG–EGA–FTIR measurement, 10 C/min heating rate, 130 mL/min air flow, initial mass 3.19 mg).
tural. While the bright yellow 1 (Pd-NN) crystallizes in triclinic
crystal system and P-1 space group, the colourless, transparent
There are six hydrogen bonded rings in the crystal of 1 (Pd-NN)
2
(Table 3, supplementary figure on crystal packing). The R (12) and
4
4
2
2
1
(Pt-NN) is monoclinic and crystallizes in the space group C2.
(Pd-NN) complex molecule is organized by the symmetry cen-
R (12) rings are heterodromic, R (10) rings are homodromic. The
4 2
biggest, overlapping R (14) rings are also heterodromic. The iden-
3
4
tre, 2 (Pt-NN) molecule is arranged by a twofold axis along the
tical rings consist of two N O and four N–H covalent bonds, four
Pd—N coordination bonds and four N-H· · ·O type hydrogen bonds.
All hydrogen bonds in 2 are also the type of N-H· · ·O. They form
a three dimensional network in b diagonal (Table 3, supplementary
figure on crystal packing). In addition to the two intramolecular
hydrogen bonds N1-H11· · ·O21 and N1-H12· · ·O31 stabilizing the
complex conformation, a two dimensional network is built by N1-
H12· · ·O21 and N1-H11· · ·O31 interactions in the bc crystallographic
plane. The former one is the shortest hydrogen bond, and connects
four complex molecules having a heterodromic loop of the type
ꢀ
N(O )PtN(O ) molecular axis. Z = 0.5 in both cases. Cell parameters
2
2
are given in Table 1. These compounds have not been included yet
into the Inorganic Crystal Structure Database (ICSD), [15], although
some structural reports have appeared about the Pd complex in
Russian [16,17].
Further details of the crystal structure investigations may
be obtained from Fachinformationszentrum Karlsruhe, 76344
Eggenstein-Leopoldshafen, Germany (fax: (+49)7247-808-666;
e-mail: crysdata@fiz-karlsruhe.de, http://www.fiz-karlsruhe.de/
request for deposited data.html) on quoting the ICSD numbers
4
4
of R (18), what can be well seen in the packing diagram viewing
[
15]: 420291 for 1 (Pd-NN) and 420292 for 2 (Pt-NN), while figures
from the a crystallographic axis. Within this ring a smaller loop of
showing the various crystal packing are available as supplementary
material deposited electronically at this journal.
4
4
R (12) is formed if we take also the longer N1-H11· · ·O31 interac-
tion into consideration. The planes are connected by N1-H13· · ·O21
The crystal structures are rich in hydrogen bonds since there
are six potential donors and four acceptors in the complexes. All
hydrogen bonds are the type of N–H· · ·O (Figs. 2 and 3, Table 3).
The main difference of the hydrogen bond systems is, that beyond
three ‘inter-complex’ type hydrogen bonds, complex 2 (Pt-NN) has
two additional strong ‘intra-complex’ type interactions compared
to 1 (Pd-NN), what seems mainly to be responsible for the differ-
ences in the structural types of crystal lattices. Anyhow, the strong
hydrogen bonds.
3
.3. Evolution of gaseous species from 1 and 2 in He and air,
measured in situ by TG/DTA–EGA–MS and TG–EGA–FTIR
spectrometric gas cell system
The thermogravimetric, as well as its time derivative (DTG), and
the DTA curves of crystal 1 (trans-Pd(NH ) (NO ) ) and 2 (trans-
3
2
2 2
‘
intra-complex’ type hydrogen bonds are responsible for differences
Pt(NH ) (NO ) ) are shown in Fig. 4. Both complex 1 and 2 are
3 2 2 2
−1
◦
observed in the 1500–1700 cm range of FTIR spectra of samples
(
in sample 1 (Pd-NN) represents a degenerative vibration mode of
N-bonded monodentate NH3 ligand [18], while sample 2 (Pt-NN)
displays split bands at 1655(s), 1600(w) and 1558(s) cm , what
stable till about 220 C, when both show an suddenly accelerated
decomposition, which is moderated in our cases with application
of sealed sample holder with a pinhole on the top. This precaution
helps to slow down the violent explosion of the samples and also
prevents the solid samples and their residues spewing out of the
crucible. The captured residues contain only crystalline phases of
metallic Pd (PDF 00-05-681, and Pt (PDF 00-04-802) [12]) according
Fig. 1). The sharp H–N–H bending vibration band at 1647 cm−1
−
1
proves that the occurrence of ‘intra-complex’ type H-bonds in 2
(
Pt-NN) eliminates the degeneration of this vibration mode.

5
8
J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
to our XRD phase analysis. The final amounts of the solid residues
of 1 (Pd-NN) and 2 (Pt-NN), 46.92% and 60.97% are close to 45.77%
and 60.74%, which are the theoretical mass levels corresponding
to metallic palladium and platinum, respectively. Stoichiometric
mass level of PdO and PtO would be 52.66% and 65.72%, respec-
tively. Anyhow presence of traces of PdO or PtO [1] cannot be
excluded.
of 1 (trans-Pd(NH ) (NO ) ) by the FTIR-spectra, as well (Fig. 7).
3 2 2 2
In addition, evolution of NO , nitrogen dioxide has also definitely
2
been observed in air (See Fig. 7). This gas could not be conclusively
detected by EGA–MS.
The evolution patterns of the individual gas components are pre-
sented in Fig. 8. The time shift of H O and CO2 signals is not part of
2
the degradation processes. Probably, initially NH forms from crys-
3
Formation of Pt from unspecified Pt(NH ) (NO ) seems to be
tal 1 (Pd-NN), whose oxidation into N O, NO and NO are catalyzed
3
2
2
2
2
2
reported several times in the literature [19–25]. Figureas et al.
19] deposited Pt metal aiming reforming catalysts. Impregnated
by the metallic Pd particles.
[
platinum catalyst, Pt/Al O3 was prepared from such precur-
sor for hydrodechlorination of CCl4 [20]. As electrocatalysts for
direct methanol fuel cells, PtRu/C [21,22] and PtRuRh/C [23] were
2
4
. Summary and conclusion
We have successfully crystallized from the impregnation solu-
tions, the crystals of analogous 1 (trans-Pd(NH ) (NO ) ), and 2
also obtained from Pt(NH ) (NO ) by thermal reduction. Vari-
3
2
2 2
3
2
2 2
ous oxide-supported Pd metal catalysts were also reported from
unspecified Pd(NH ) (NO ) by impregnation methods (on SnO2,
(trans-Pd(NH ) (NO ) ), respectively. The molecular and crystal
3 2 2 2
3
2
2 2
structures have been determined by single crystal X-ray diffraction,
and their thermal stability has also been studied. The chemically
and configurationally analogous compounds crystallized in differ-
ent crystal systems and space groups having also different network
ZrO , CeO [24], or on SiO2 [25,26]. Even effect of noble metals (Pt
2
2
or Pd coming from the above precursors) on VOCs (aromatic volatile
organic carbons) sensing properties of WO3 thin film sensors were
also studied [27].
◦
of intermolecular interactions. They are both stable till ca. 220 C,
Kinoshita et al. [28] studied the thermal stability of platinum
when they suddenly decompose both in inert (He) and in oxi-
dizing (air) atmosphere. We have also been able to capture the
spewing residues of thermal decomposition in a sealed Al crucible
with a pinhole on the top used in simultaneous TG/DTA experi-
ments. Despite former XPS findings [1] the amount of residues and
their powder X-ray diffraction phase analysis shows single step
and stoichiometric formation of metallic palladium and platinum,
diamino dinitrite (Pt(NH ) (NO ) ) for preparation Pt catalyst in
3
2
2 2
flowing hydrogen, argon, air, oxygen, and vacuum by thermo-
gravimetry (TG), and separately in air, argon, and hydrogen by
DTA, in open crucibles, at about 10 mg of initial mass. The ther-
mal decomposition of Pt(NH ) (NO ) had occurred with a rapid,
3
2
2 2
violent weight loss at well defined temperatures depending on the
◦
surrounding gas environment, at 127, 208, 230, 232, and 180 C
respectively. Thermal degradation of a [Pt(NH )5OH]Cl .H O salt
3
3
2
in hydrogen, argon, air, oxygen, and vacuum, respectively [28].
Exothermic heat effect escorted the decomposition even in air,
argon, and hydrogen, although poor agreement was observed for
the onset temperatures of thermal decomposition in the sepa-
rate TG and DTA apparatuses [28]. Hernandez and Choren studied
also the thermal decomposition of diammineplatinum(II) nitrit
[
30] in oxygen produced PtO as an intermediate before the forma-
2
◦
tion of Pt above 430 C, but it is not happened in our case.
In situ evolved gas analysis of the released gas mixture from
decomposition of both compounds indicated and monitored the
formation of N , H O, NH , N O, and NO gases as gaseous prod-
uct components (even presence of NO2 could not be excluded)
by TG/DTA–EGA–MS in He purge atmosphere, while TG–EGA–FTIR
2
2
3
2
(
Pt(NH ) (NO ) ) in oxygen, helium and hydrogen observing sin-
3 2 2 2
◦
gle step decomposition at temperatures 240, 240, and 125 C,
respectively, accompanied by highly exothermic effects in all atmo-
spheres, while the solid products of transformation was calculated
to be Pt according to TG diagrams [29] in all the cases.
spectroscopy in air has also proven the elaboration of H O, NH ,
N O, NO and NO , (unfortunately N is not IR active and not
2
3
2
2
2
detectable by FTIR). Beyond water and nitrogen formation [18],
the occurrence of ammonia and various nitrogen oxides represent
a more sophisticated degradation mechanism of the compounds,
which seems to be not too much influenced neither by the inertness
nor oxidative nature of atmosphere used for the thermal decompo-
sition, or by the different H-bonding system of the two complexes.
The intense and violent exothermic gas evolution from these
solid complexes 1 and 2 at about 220 C makes them probably sen-
sitive to shock, what needs to be essentially beware in mind during
a scaling up of sensor fabrication.
In our simultaneous TG/DTA experiments of 1 (Pd-NN), the sin-
gle pinhole has usually become probably temporary closed by some
solid particles of sample, resulting in delayed and varied dynamics
and in some more virtual stages of decomposition shown by both
TG, DTG, and DTA curves, compared to the smooth changes in case
of 2 (Pt-NN) cf. Fig. 4a and b.
◦
The evolution courses of individual gaseous products of
decomposing crystal 1 (trans-Pd(NH ) (NO ) ) and
2
(trans-
3
2
2 2
Pt(NH ) (NO ) ), as identified and monitored by TG/DTA–EGA–MS
3
2
2 2
in He are shown in Fig. 5. The ion fragments, which suffered changes,
indicate (at least, do not exclude) the evolution of N , H O, NH ,
Acknowledgements
2
2
3
N O, and NO gases during the decomposition, what follows the
overall dynamics of mass losses represented by the DTG curves.
The TG/DTA–EGA–MS experiments carried out in air (Fig. 6) for
2
P.B. and M.C. acknowledge the National Science and Tech-
nology Office for an X-ray diffractometer purchase grant (MU-
0
0338/2003). J.M. and G.P. also thanks for the purchase grant of
1
(trans-Pd(NH ) (NO ) ) and 2 (trans-Pt(NH ) (NO ) ) could only
3 2 2 2 3 2 2 2
a new HT-XRD apparatus supported by the EU and Hungarian gov-
ernment (GVOP-3.2.1.-2004-04-0224, KMA).
confirm evolution of H O, N O and NO in both cases, but the MS
2
2
system was not able to detect of N2 and NH , because of the vast
3
presence of nitrogen originating from the flowing air and providing
high lever of background and background noises.
Appendix A. Supplementary data
According to Figureas et al. [19] Pt(NH ) (NO ) ) decomposes
3
2
2 2
under vacuum into nitrogen and water, unfortunately neither
experimental proof nor source of reference was given on the chem-
ical identity of evolved gases.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tca.2009.02.006.
In order to check the identity of the evolved gases, comparatively
TG–EGA–FTIR gas cell measuring system has also been applied. In
References
air, the evolution of the various gases (H O, NH , N O, and NO,
2
3
2
[1] G. Kiss, V.K. Josepovits, K. Kovács, B. Ostrick, M. Fleischer, H. Meixner, F. Réti,
Thin Solid Films 436 (2003) 115–118.
except N , which is not detectable by FTIR) is confirmed in case
2

J. Madarász et al. / Thermochimica Acta 490 (2009) 51–59
59
[
2] K. Harms, XCAD4 Data Reduction Program for CAD4 Diffractometers, Philipps-
Universität Marburg, Germany, 1996.
[15] Inorganic Crystal Structure Database (ICSD), Fachinformationszentrum Karl-
sruhe (FIZ) and National Institute of Standards and Technology (NIST), Version
Release 2008/2.
[16] S.A. Gromilov, S.P. Khranenko, V.I. Alekseev, I.A. Baidina, A.V. Belyaev, Zh. Neor-
gan. Khim. 43 (1998) 427–429 (Russ.), CA 129:10928.
[
3] A.C. North, D.C. Philips, F. Mathews, Acta Cryst. A24 (1968) 350–359.
4] G.M. Sheldrick, SHELXS-97 Program for Crystal Structure Solution, University
of Göttingen, Germany, 1997.
[
[
5] G.M. Sheldrick, SHELXL-97 Program for Crystal Structure Refinement, Univer-
sity of Göttingen, Germany, 1997.
[17] A.I. Blokhin, L.A. Solov’ev, M.L. Blokhina, I.S. Yakimov, S.D. Kirik, Russ. J. Coord.
Chem. (Transl. Koordinatsionnaya Khimiya) 22 (1996) 185–189, CA 124: 275020.
[18] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Com-
pounds, Wiley-Interscience, 1986.
[6] International Tables for X-ray Crystallography Vol. C., in: A.J.C. Wilson (Ed.),
Kluwer Academic Publishers, Dordrecht, Tables 6.1.1.4 (pp. 500–502), 4.2.6.8
(
pp. 219–222) and 4.2.4.2 (pp. 193–199), 1992.
7] A.L. Spek, Acta Cryst. A46, C-34, Windows implementation by L.J. Farrugia,
1998), Department of Chemistry, University of Glasgow, UK, 1990.
[19] F. Figureas, B. Mencier, L. de Mourgues, C. Naccache, Y. Trambouze, J. Catal. 19
(1970) 315–321.
[20] T. Kawaguchi, Y. Rachi, W. Sugimoto, Y. Murakami, Y. Takasu, J. Appl. Elec-
trochem. 36 (2006) 1117–1125.
[21] Z.B. Wang, G.P. Yin, P.F. Shi, J. Power Sources 163 (2007) 688–694.
[22] Z.B. Wang, G.P. Yin, P.F. Shi, J. Electrochem. Soc. 152 (2005) A2406–A2412.
[23] J.W. Bae, I.G. Kim, J.S. Lee, K.H. Lee, E.J. Jang, Appl. Catal. A: Gen. 240 (2003)
129–142.
[
[
(
8] M.N. Burnett, C.K. Johnson, ORTEP-III, ORNL Report 6895, Windows implemen-
tation by, L.J. Farrugia (1998), Department of Chemistry, University of Glasgow,
UK, 1996.
9] NIST Chemistry Webbook Standard Reference Database No. 69, June 2005
Release (http://webbook.nist.gov/chemistry).
[
[
10] Spectral Database for Organic Compounds, SDBS, National Institute of Advanced
Industrial Science and Technology, Japan, http://riodb01.ibase.aist.go.jp/sdbs/
cgi-bin/direct frame top.cgi.
[24] T. Mitsui, K. Tsutsui, T. Matsui, R. Kikuchi, K. Eguchi, Appl. Catal. B: Environ. 78
(2008) 158–165.
[25] J. Sakauchi, H. Sakagami, N. Takahashi, T. Matsuda, Y. Imizu, Catal. Lett. 99 (2005)
257–261.
[
11] M. Le Postollec, J.-P. Mathieu, H. Poulet, J. Chim. Phys. Phys. Chim. Biol. 60 (1963)
1
319–1333 (Fr.) CA 60:57358.
[26] K. Ito, M. Ohshima, H. Kurokawa, K. Sugiyama, H. Miura, Catal. Commun. 3
(2002) 527–531.
[
12] International Centre for Diffraction Data (ICDD), Powder Diffraction File (PDF),
PDF-2 Release, 2007.
13] S. Kirik, I. Yakimov, A. Blohkin, L. Soloyov, Institute of Chemistry, Academy of
Science, Krasnoyarsk, Russia, ICDD Grant-in-Aid, 1994.
[27] K. Kanematsu, J. Tamaki, S. Kajita, Chem. Sensors 23 (Suppl. B) (2007) 34–36.
[28] K. Kinoshita, K. Routsis, J.A.S. Bett, Thermochim. Acta 10 (1974) 109–117.
[29] J.O. Hernández, E.A. Choren, Thermochim. Acta 71 (1983) 265–272.
[30] H. Hokkanen, T. Leskelä, L. Niinistö, H.A. Laitinen, Thermochim. Acta 191 (1991)
35–40.
[
[
14] S. Kirik, L. Solovyov, A. Blohkin, R. Mulagaleev, Institute Of Chemistry, Academy
of Science, Krasnoyarsk, Russia, ICDD Grant-in-Aid.(2002).