Synthesis and characterization of [Co(NH3)5NO 2][M(NO2)4] (M = Pt, Pd) compounds and their thermolysis products

Article abstract of DOI:10.1134/S0036023606040024

Compounds [Co(NH₃)₅NO₂][Pd(NO ₂)₄] (I) and [Co(NH₃)₅NO ₂][Pt(NO₂)₄] ? 1.5H₂O (II) have been crystallized from solution. Their crystal

Full text of DOI:10.1134/S0036023606040024

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2006, Vol. 51, No. 4, pp. 521–530. © Pleiades Publishing, Inc., 2006.
Original Russian Text © K.V. Yusenko, Yu.V. Shubin, O.N. Skryabina, I.A. Baidina, S.V. Korenev, 2006, published in Zhurnal Neorganicheskoi Khimii, 2006, Vol. 51, No. 4,
pp. 573–582.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Synthesis and Characterization
of [Co(NH3)5NO2][M(NO2)4] (M = Pt, Pd) Compounds
and Their Thermolysis Products
a
a
b
a
a
K. V. Yusenko , Yu. V. Shubin , O. N. Skryabina , I. A. Baidina , and S. V. Korenev
a
Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia
e-mail: yusenko@che.nsk.su
Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090 Russia
b
Received June 16, 2005
Abstract—Compounds [Co(NH3)5NO2][Pd(NO2)4] (I) and [Co(NH3)5NO2][Pt(NO2)4] · 1.5H2O (II) have
been crystallized from solution. Their crystal structures have been solved, and thermolysis under various con-
ditions studied. The thermolysis products are Co0.5M0.5 ordered solid solutions.
DOI: 10.1134/S0036023606040024
The syntheses and structures of double complex in the form of yellow platelets for M = Pd or orange
salts containing a complex cation and a complex anion needles for M = Pt. The precipitate was allowed to
have been studied for a sufficiently long time [1], but stand for 10 min; then, it was vacuum filtered, washed
the study by Michelot and colleagues [2] has spurred with acetone, and dried in air. Yield: 75–85%.
interest in their thermolysis and final thermolysis prod-
ucts in various gas atmospheres. Michelot and col-
leagues [2] noticed that [Ir(NH3)5Cl][PtCl4] thermoly-
sis under a hydrogen atmosphere finally yielded
Ir0.5Pt0.5 solid solution. The Ir0.5Pt0.5 solid solution was
formed after the salt was applied to alumina pellets and
reduced in the support phase. Michelot and colleagues
[2] also demonstrated that this support system can serve
as a reforming catalyst.
Element analysis was by atomic absorption on a
Hitachi Z800 spectrometer with Zeeman background
correction. A salt aliquot was dissolved in water in the
presence of hydrochloric acid under heating. The total
of metals was determined by reducing the salt aliquot in
flowing hydrogen in a boat inside a reactor (both made
of fused silica).
The results of element analysis for compound I were
as below.
Substituting nonprecious cobalt for precious iridium
lowers the catalyst’s cost and improves its characteris-
tics [3]. Another way to improve the characteristics of
the catalysts is to use precursor complexes free of
halide ions. Here, we have synthesized and character-
ized such compounds: [Co(NH3)5NO2][Pd(NO2)4] (I)
and [Co(NH3)5NO2][Pt(NO2)4] · 1.5H2O (II). Our
efforts were directed to solving the structure of the
complexes and studying their transformations under
various conditions.
For H15N10O10CoPd anal. calcd., %: Co, 12.26; Pd,
22.15; Co + Pd, 34.41.
Found, %: Co, 11.2 0.5; Pd, 18.9 0.5; Co + Pd,
34.8 0.2.
The results of element analysis for compound II
were as below.
For H18N10O11.5CoPt anal. calcd., %: Co, 9.8; Pt,
35.2; Co + Pt, 41.61.
Found, %: Co, 9.6 0.5; Pt, 35.2 0.5; Co + Pt,
42.7 0.2.
The thermogravimetric properties of the compounds
were studied on a Q-1000 derivatograph modified to
operate in various gas atmospheres. A sample about
15 mg in size was mixed with a tenfold amount of
Al2O3 and transferred into a covered platinum crucible.
The heating rate was 3 K/min in flowing helium
(150 ml/min).
Polycrystal X-ray diffraction experiments were car-
ried out for ethanol mulls applied to the polished side of
a fused silica cell (DRON Seifert RM4, CuKα radiation,
EXPERIMENTAL
The starting chemicals used ([Co(NH3)5NO2]Cl2,
K2[Pt(NO2)4], and K2[Pd(NO2)4]) were prepared by
procedures described elsewhere [4, 5].
Phases of the double complex salts were prepared as
follows. A [Co(NH3)5NO2]Cl2 sample (0.5 mmol) was
dissolved in minimum hot water and mixed with a solu-
tion of K2[M(NO2)4] (0.5 mmol) in minimum hot water.
After some time, double complex crystals precipitated
521

522
YUSENKO et al.
Table 1. Crystal data and details of the X-ray diffraction ex- Table 2. Atomic coordinates (×104) and equivalent thermal
periment
parameters (Å2 × 103) for complex I
Atom
x/a
y/b
z/c
Ueq, Å2
Parameter
I
II
Pd(1)
7373(1)
7019(1)
4344(1)
1598(1)
4273(1)
4400(1)
4346(9)
3419(12)
5206(10)
5116(9)
6517(8)
4302(8)
4069(8)
5204(8)
2695(10)
3524(8)
4123(15)
2853(12)
6416(9)
5955(9)
2421(9)
4643(10)
4105(9)
2895(8)
1741(9)
3035(7)
22(1)
21(1)
35(2)
72(2)
66(2)
28(2)
46(2)
42(2)
23(2)
43(2)
54(2)
16(1)
97(3)
91(3)
27(2)
27(2)
26(2)
31(2)
33(2)
29(2)
46(2)
38(2)
Formula weight
a, Å
480.55
587.26
Co(1)
N(1)
8.0209(8) 7.7583(8)
22.167(2) 9.6385(9)
7.8453(8) 10.9641(11)
5904(10) 5083(3)
4512(10) 5096(3)
6354(11) 5520(3)
5551(10) 3822(3)
b, Å
O(11)
O(12)
N(2)
c, Å
α, deg
β, deg
γ, deg
90
97.216(2)
98.836(2) 92.090(2)
O(21)
O(22)
N(3)
5952(9)
4130(8)
8787(8)
9116(9)
3567(3)
3775(3)
3591(3)
3228(3)
90
112.2500(10)
Space group
Cc
P1
O(31)
O(32)
N(4)
V, Å3
1378.3(2) 749.66(13)
9283(10) 3525(3)
9379(9) 4896(3)
Z
4
2
ρ
ρ
calc, g/cm3
meas, g/cm3
2.316
2.602
O(41)
O(42)
N(5)
10554(17) 4748(4)
8932(13) 5294(5)
2.29 0.01 2.70 0.02
2.73–23.27 2.31–23.27
6937(9)
7206(10)
7082(9)
9421(9)
4522(9)
6738(9)
2139(3)
884(3)
θ range, deg
N(6)
Number of measured reflections
Number of unique reflections
R for reflections with I > 2σ(I)
2661
1317
3268
2662
N(7)
1073(3)
1685(3)
1522(3)
2280(3)
N(8)
0.0247
0.0180
0.0443
0.0189
0.0449
N(9)
wR for reflections with I > 2σ(I) 0.0583
N(10)
O(101)
O(102)
R for all reflections
wR for all reflections
0.0248
0.0584
7611(10) 2340(3)
5632(8) 2662(3)
SHELX97 program package [8] was used in all compu-
tations. The atomic coordinates in the structures of
compounds I and II are listed in Tables 2 and 3.
Selected bond lengths and bond angles are listed in
Tables 4 and 5.
graphite monochromator on the reflected beam, scintil-
lation detector with amplitude discrimination, frame
mode). A polycrystalline silicon sample (a = 5.4309 Å)
prepared in the same manner was the external standard.
The 2θ range was from 5° to 60° for the complex salt
and from 5° to 135° for the thermolysis products.
The X-ray diffraction patterns were indexed com-
pletely on the basis of the single-crystal data; therefore,
the samples were single phases. X-ray phase analysis
was performed by analogy with X-ray diffraction pat-
terns for pure metals and intermetallic compounds from
the PDF file [6]. The parameters of the metal phases
were refined over the entire data set using the Powder-
Cell 2.3 program [7].
RESULTS AND DISCUSSION
The method we developed for the synthesis of dou-
ble complex salts allows us to prepare single crystals
suitable for X-ray diffraction experiment. Double com-
plex salts I and II have different crystal-water concen-
trations. Therefore, their structural features will be
described separately.
Single-crystal X-ray diffraction experiments were
carried out (the unit cell parameters were refined, and
the X-ray diffraction reflection intensities were mea-
sured in order to solve the crystal structures) on a
Bruker AXS P4 diffractometer (MoKα radiation, graph-
ite monochromator, θ/2θ scan mode, room tempera-
ture). The crystal data, experimental details, and refine-
ment parameters are listed in Table 1. The structures
were solved by the standard heavy-atom method and
Crystal structure of [Co(NH3)5NO2][Pd(NO2)4]
(compound I). A comparative crystal-chemical analy-
sis of the compounds of the [Pd(NO2)4]2– anion was
carried out in [9]. The configuration of the anion was
found to vary noticeably depending on the cation. Com-
pound I contains a rather bulky complex cation capable
of hydrogen bonding with the anion.
The compound crystallizes in yellow monoclinic
refined in the anisotropic approximation. The platelets. The crystal structure is built of isolated
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SYNTHESIS AND CHARACTERIZATION OF [Co(NH3)5NO2][M(NO2)4]
523
Table 3. Atomic coordinates (×104) and equivalent thermal parameters (Å2 × 103) for complex II
Atom
x/a
y/b
z/c
Ueq, Å2
Pt(1)
–2976(1)
–5233(1)
6671(1)
3316(1)
1761(1)
–4705(1)
6567(3)
29(1)
28(1)
24(1)
23(1)
29(4)
60(6)
38(5)
21(3)
36(4)
33(5)
38(5)
28(4)
48(5)
43(5)
40(5)
35(5)
44(5)
37(4)
47(5)
52(5)
33(4)
36(5)
78(8)
42(5)
45(5)
33(4)
47(5)
55(6)
51(4)
69(5)
56(5)
57(4)
100(6)
119(5)
113(8)
167(11)
102(8)
63(5)
61(5)
66(6)
203(15)
50(4)
144(6)
186(14)
133(9)
74(4)
Pt(2)
Co(1)
Co(2)
N(11)
N(12)
N(13)
N(14)
N(15)
N(16)
N(21)
N(22)
N(23)
N(24)
N(25)
N(26)
O(16A)
O(16B)
O(26A)
O(26B)
N(1)
2750(4)
8127(3)
–10975(4)
1580(20)
1866(3)
459(3)
6252(15)
8456(19)
6988(16)
7769(12)
9317(17)
9942(16)
3800(18)
1467(16)
2174(18)
2956(16)
732(16)
5362(15)
6490(20)
7938(13)
6659(14)
5222(14)
7736(18)
1666(16)
498(15)
470(30)
1960(20)
5070(17)
3510(20)
3865(18)
–9830(20)
–8642(18)
–13300(20)
–10130(20)
–11810(20)
–12170(30)
3140(20)
389(16)
–929(14)
1823(15)
–685(14)
8655(16)
7567(11)
–1634(15)
–487(15)
620(20)
17(18)
10123(17)
10893(14)
–170(15)
–943(14)
5620(20)
6720(19)
6691(18)
7600(20)
4370(20)
3293(17)
2370(20)
3360(20)
6166(17)
4342(18)
5557(16)
7970(15)
5660(20)
7934(14)
7190(20)
8390(30)
5680(19)
3810(20)
4467(16)
2127(17)
1200(20)
2769(17)
3158(18)
3800(40)
590(20)
5450(20)
–11310(20)
–13637(19)
–5320(30)
–1330(20)
–4640(30)
–790(30)
N(2)
422(18)
N(3)
3180(20)
2993(19)
–3470(20)
–3320(18)
–5850(20)
–6044(19)
444(18)
N(4)
N(5)
–2970(30)
–6930(20)
–7670(30)
–3580(20)
–6350(20)
–5590(20)
–1080(20)
–310(20)
N(6)
N(7)
N(8)
O(11)
O(12)
O(21)
O(22)
O(31)
O(32)
O(41)
O(42)
O(51)
O(52)
O(61)
O(62)
O(71)
O(72)
O(81)
O(82)
O(1W)
O(2W)
–2(15)
–122(14)
89(18)
–5930(30)
–4630(18)
610(30)
3250(20)
3522(12)
2930(20)
3878(16)
–3120(20)
–3311(19)
–2900(17)
–3015(18)
–6540(20)
–5826(13)
–7294(11)
–6130(20)
5320(20)
–8487(15)
–670(30)
–2590(30)
–1700(20)
–6920(20)
–7810(20)
–7930(30)
–8779(18)
–4510(20)
–2140(30)
7790(30)
–6030(30)
–400(20)
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006

524
YUSENKO et al.
Table 4. Bond lengths (d) and bond angles (ω) in the structure of I
Bond
d, Å
Angle
ω, deg
Pd(1)–N(1)
Pd(1)–N(3)
Pd(1)–N(2)
Pd(1)–N(4)
2.025(7)
2.037(7)
2.052(8)
2.173(7)
1.911(7)
1.916(7)
1.946(7)
1.988(7)
1.990(7)
1.995(7)
1.204(10)
1.236(10)
1.222(10)
1.233(9)
1.199(8)
1.214(9)
1.040(13)
1.061(12)
1.233(9)
1.243(9)
N(10)Co(1)N(8)
N(10)Co(1)N(7)
N(8)Co(1)N(7)
N(10)Co(1)N(9)
N(8)Co(1)N(9)
N(7)Co(1)N(9)
N(10)Co(1)N(6)
N(8)Co(1)N(6)
N(7)Co(1)N(6)
N(9)Co(1)N(6)
N(10)Co(1)N(5)
N(8)Co(1)N(5)
N(7)Co(1)N(5)
N(9)Co(1)N(5)
N(6)Co(1)N(5)
O(12)N(1)O(11)
O(12)N(1)Pd(1)
O(11)N(1)Pd(1)
O(22)N(2)O(21)
O(22)N(2)Pd(1)
O(21)N(2)Pd(1)
O(31)N(3)O(32)
O(31)N(3)Pd(1)
O(32)N(3)Pd(1)
O(41)N(4)O(42)
O(41)N(4)Pd(1)
O(42)N(4)Pd(1)
O(101)N(10)O(102)
O(102)N(10)Co(1)
90.2(3)
89.7(3)
89.5(3)
88.5(3)
Co(1)–N(10)
Co(1)–N(8)
Co(1)–N(7)
Co(1)–N(9)
Co(1)–N(6)
Co(1)–N(5)
N(1)–O(12)
N(1)–O(11)
N(2)–O(22)
N(2)–O(21)
N(3)–O(31)
N(3)–O(32)
N(4)–O(41)
N(4)–O(42)
N(10)–O(101)
N(10)–O(102)
178.6(3)
90.4(3)
177.6(3)
92.3(3)
90.3(3)
89.1(3)
89.9(3)
90.9(3)
179.5(3)
89.3(3)
90.1(3)
118.5(8)
122.8(6)
118.7(6)
121.4(8)
122.2(6)
116.3(6)
121.0(7)
123.5(5)
115.5(6)
134.4(10)
111.0(7)
113.3(7)
118.9(7)
120.2(5)
Angle
ω, deg
176.9(3)
90.0(3)
89.8(3)
90.6(3)
89.8(2)
176.9(3)
120.9(6)
N(1)Pd(1)N(3)
N(1)Pd(1)N(2)
N(3)Pd(1)N(2)
N(1)Pd(1)N(4)
N(3)Pd(1)N(4)
N(2)Pd(1)N(4)
O(101)N(10)Co(1)
[Co(NH3)5NO2]2+ complex cations and [Pd(NO2)4]2–
anions; both species have no symmetry elements. The
Pd atom is coordinated by the nitrogen atoms of the
four nitro groups that form a slightly distorted square;
the Pd–N bond lengths average 2.072 Å; the NPdN
bond angles approach 90°. The PdN4 coordination
square is nearly planar; the departures of the atoms are
within 0.05 Å. The angles formed by the NO2 groups
with the square coordination plane are listed in Table 6,
compared with the geometry of some tetranitropalla-
dates(II). In all structures containing the [Pd(NO2)4]2–
complex anion, the square coordination of Pd is trans-
formed to an extended bipyramid due to Pd···O(NO2)
contacts. In compound I the square-planar coordination
of the Pd atom is transformed to (4 + 1 + 1) due to two
nitro oxygen atoms from neighboring complex anions,
with Pd···O distances of 3.003 and 3.184 Å. Zigzag
chains of complex anions with a Pd···Pd distance of
4.884 Å and a PdPdPd angle of 106.9° running along
axis z are formed due to such contacts. A chain frag-
ment is shown in Fig. 1. The nitro groups of the anion
have the following geometry: N–Oav = 1.18 Å, and
ꢀONOav = 123°. It is interesting that the geometry of
the nitro groups involved in the extra coordination of
the palladium atom differs noticeably from the average
values: the N–O bonds are shortened to 1.04 Å, the
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SYNTHESIS AND CHARACTERIZATION OF [Co(NH3)5NO2][M(NO2)4]
Table 5. Bond lengths (d) and bond angles (ω) in the structure of II
525
Bond
d, Å
Angle
ω, deg
Pt(1)–N(4)
Pt(1)–N(2)
Pt(1)–N(1)
Pt(1)–N(3)
Pt(2)–N(8)
Pt(2)–N(5)
Pt(2)–N(6)
Pt(2)–N(7)
1.972(16)
1.975(19)
2.003(19)
2.06(3)
1.98(2)
2.02(2)
N(12)Co(1)N(15)
N(16)Co(1)N(15)
N(13)Co(1)N(15)
N(12)Co(1)N(14)
N(16)Co(1)N(14)
N(13)Co(1)N(14)
N(15)Co(1)N(14)
N(12)Co(1)N(11)
N(16)Co(1)N(11)
N(13)Co(1)N(11)
N(15)Co(1)N(11)
N(14)Co(1)N(11)
N(26)Co(2)N(23)
N(26)Co(2)N(25)
N(23)Co(2)N(25)
N(26)Co(2)N(24)
N(23)Co(2)N(24)
N(25)Co(2)N(24)
N(26)Co(2)N(22)
N(23)Co(2)N(22)
N(25)Co(2)N(22)
N(24)Co(2)N(22)
N(26)Co(2)N(21)
N(23)Co(2)N(21)
N(25)Co(2)N(21)
N(24)Co(2)N(21)
N(22)Co(2)N(21)
O(16A)N(16)O(16B)
O(16A)N(16)Co(1)
O(16B)N(16)Co(1)
O(26B)N(26)O(26A)
O(26B)N(26)Co(2)
O(26A)N(26)Co(2)
O(11)N(1)O(12)
O(11)N(1)Pt(1)
O(12)N(1)Pt(1)
O(22)N(2)O(21)
O(22)N(2)Pt(1)
O(21)N(2)Pt(1)
O(31)N(3)O(32)
O(31)N(3)Pt(1)
O(32)N(3)Pt(1)
O(42)N(4)O(41)
O(42)N(4)Pt(1)
O(41)N(4)Pt(1)
O(51)N(5)O(52)
O(51)N(5)Pt(2)
O(52)N(5)Pt(2)
O(61)N(6)O(62)
O(61)N(6)Pt(2)
O(62)N(6)Pt(2)
O(72)N(7)O(71)
O(72)N(7)Pt(2)
O(71)N(7)Pt(2)
O(82)N(8)O(81)
O(82)N(8)Pt(2)
88.0(8)
89.7(7)
178.0(6)
179.4(7)
90.8(6)
88.9(6)
92.6(6)
90.2(7)
179.7(7)
91.0(7)
90.4(7)
89.5(6)
88.9(7)
89.5(7)
88.7(7)
89.3(7)
92.1(7)
178.5(6)
88.9(6)
177.7(6)
90.8(7)
88.4(7)
2.04(2)
2.05(2)
Co(1)–N(12)
Co(1)–N(16)
Co(1)–N(13)
Co(1)–N(15)
Co(1)–N(14)
Co(1)–N(11)
Co(2)–N(26)
Co(2)–N(23)
Co(2)–N(25)
Co(2)–N(24)
Co(2)–N(22)
Co(2)–N(21)
N(16)–O(16A)
N(16)–O(16B)
N(26)–O(26B)
N(26)–O(26A)
N(1)–O(11)
N(1)–O(12)
N(2)–O(22)
N(2)–O(21)
N(3)–O(31)
N(3)–O(32)
N(4)–O(42)
N(4)–O(41)
N(5)–O(51)
N(5)–O(52)
N(6)–O(61)
N(6)–O(62)
N(7)–O(72)
N(7)–O(71)
N(8)–O(82)
N(8)–O(81)
1.912(19)
1.913(15)
1.952(15)
1.953(17)
1.958(11)
1.976(14)
1.927(16)
1.936(16)
1.948(16)
1.950(17)
1.987(11)
2.014(15)
1.20(2)
1.26(2)
1.21(2)
1.29(2)
1.13(2)
1.27(2)
1.27(2)
1.28(2)
1.13(3)
177.7(7)
88.8(7)
89.9(7)
91.3(7)
93.4(6)
120.4(15)
120.7(12)
118.7(14)
122.1(15)
120.8(13)
117.1(14)
118.5(19)
122.8(16)
118.5(13)
114.5(19)
120.8(13)
124.6(15)
119(3)
120.1(19)
112.7(15)
112.3(18)
126.0(16)
121.1(16)
119.0(19)
116.6(17)
121.9(15)
126(2)
1.21(2)
1.13(2)
1.28(2)
1.19(2)
1.32(2)
1.16(2)
1.17(2)
1.07(2)
1.22(2)
1.04(3)
1.48(2)
Angle
ω, deg
90.7(8)
175.0(11)
93.4(8)
87.9(9)
178.1(7)
88.1(9)
90.1(8)
179.3(8)
89.5(8)
95.1(9)
173.6(10)
85.2(9)
89.5(7)
90.5(8)
88.9(7)
N(4)Pt(1)N(2)
N(4)Pt(1)N(1)
N(2)Pt(1)N(1)
N(4)Pt(1)N(3)
N(2)Pt(1)N(3)
N(1)Pt(1)N(3)
N(8)Pt(2)N(5)
N(8)Pt(2)N(6)
N(5)Pt(2)N(6)
N(8)Pt(2)N(7)
N(5)Pt(2)N(7)
N(6)Pt(2)N(7)
N(12)Co(1)N(16)
N(12)Co(1)N(13)
N(16)Co(1)N(13)
115.8(14)
118.5(14)
117(2)
124.9(17)
117.5(16)
106(2)
137(2)
113.7(10)
O(81)N(8)Pt(2)
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006

526
YUSENKO et al.
Table 6. Comparative geometry of [M(NO2)4]2– anions in the structures of salts according to [10] and this work*
Pd–N, Å
ONO, deg
Complex
NPdN, deg
N–O, Å
Pd···O, Å
3.10
ϕ, deg
n
Li2[Pd(NO2)4] · 2H2O
2.029–2.037
1.197–2.240
118–122
88.44, 91.56
56 (×2), 48, 73
1
Na2[Pd(NO2)4]
2.015–2.053
1.190–1.261
1.226–1.239
1.211–1.247
0.98–1.29
118–121
32, 70
2.90
3.25 Ë 3.28
3.09
87.5–91.8
1
K2[Pd(NO2)4]
2.013–2.047
119–119
88
43, 54, 69, 88
2
β-Rb2[Pd(NO2)4]
α-Cs2[Pd(NO2)4]
[Co(NH3)5NO2][Pd(NO2)4]
2.019, 2.038
118, 119
82, 28
89, 29
1
1.980–2.120
108–128
6, 88
–
87
3
2.025–2.173
89.8–90.0
1
1.040–1.236
118–134
3.10
59, 63, 53, 38
Pt–N, Å
NPtN, deg
n
ONO, deg
ϕ, deg
Pt···O, Å
Pt···N, Å
Complex
N–O, Å
K2[Pt(NO2)4]
2.030–2.047
1.197–1.252
120
–
88
49, 86 (×2), 40, 67, 71
2
1.972–2.050
88–93
2
[Co(NH3)5NO2][Pt(NO2)4] · 1.5H2O
1.04–1.48
106–120
3.405
3.626
62, 69, 66, 46
16, 52, 70, 74
* n—number of independent [M(NO ] ] complex anions in the structure; ϕ—angle formed by the nitro group and the [M(NO ) ] square plane.
2 4
2 4
ONO angle is increased to 134°, the Pd–N(4) distance deviate by 2.4° from their ideal values. The shortest
is 0.1 Å longer than the average value, and the angle
formed by the plane of this ligand with the PdN4 coor-
Co···Co contacts in the structure are 6.530 Å; the eight
shortest distances between the centers of the complex
dination square is smaller than the angles formed by the anions and complex cations fall in the range 6.287–
other ligands.
7.970 Å.
The Co atoms in the structure of I are surrounded by
an octahedral array of atoms (CoN6) formed by the five
ammonia molecules and the NO2 group. The Co–
N(NH3) bond lengths average 1.967 Å; the Co–N(NO2)
Structural fragments are linked through weak
hydrogen bonds; the minimal estimates of the N–H···O
(N···O) distances are 2.89 Å. The shortest contact
between the oxygen atoms O(CoNO2)···O(PdNO2) is
distance is 1.911 Å. The bond angles at the Co atoms 2.99 Å.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006

SYNTHESIS AND CHARACTERIZATION OF [Co(NH3)5NO2][M(NO2)4]
527
O(101)
N(7)
N(10)
O(32)
N(9)
N(6)
O(11)
N(1)
O(102)
N(8)
O(22)
N(4)
Pd(1)
O(42)
O(41)
N(3)
Co(1)
O(31)
N(2)
O(12)
N(5)
3.184
O(21)
3.003
Fig. 1. Fragment of the crystal structure of I. The dashed lines show the shortest Pd···O distances (in Å).
N(13)
Crystal structure of [Co(NH3)5NO2][Pt(NO2)4] ·
1.5H2O (compound II). The crystal chemistry of com-
plexes with the [Pt(NO2)4]2– anion is less known. Crys-
N(11)
O(16A)
N(14)
N(12)
N(16)
O(16B)
tal chemistry has been described for K2[Pt(NO2)4] [9]
and Ag4A2[Pt(NO2)4]3 with A = K or Rb [10].
Co(1)
The structure of salt II is built of isolated
[Co(NH3)5NO2]2+ complex cations, [Pt(NO2)4]2– com-
plex anions, and crystal water molecules (Fig. 2). There
are two crystallographically independent complex cat-
ions and two crystallographically independent complex
anions in the structure; the complex species are in gen-
eral positions. The geometric parameters of the com-
plex cations are the following: Co–N(NH3)av = 1.96 Å,
Co–N(NO2) = 1.92 Å, N–Oav = 1.24 Å, ꢀONOav =
121°. The shortest Co···ëÓ distance in the structure of II
is 6.020 Å. The coordination polyhedra around the Pt
atoms are slightly distorted squares formed by the four
nitro nitrogen atoms; the average Pt–N bond length is
2.01 Å; deviation of the NPtN angles from ideal values
(90° and 180°) reaches 6.4°. The PtN4 fragments are
planar squares; the departure of the atoms from the
coordination plane is no more than 0.03 Å. The planes
of the Pt(1) and Pt(2) coordination squares are nearly
parallel; the angle formed by the normals to these
planes is as small as 0.3°. The geometric parameters of
the [Pt(NO2)4]2– complex anions, including the angles
of the nitro groups, are listed in Table 6. The
N(15)
O(1W)
O(71)
O(62)
O(52)
N(6)
Pt(2)
N(7)
N(7)
O(61)
O(82)
O(81)
O(72)
3.112
N(8)
O(51)
3.353
O(31)
N(3)
O(41)
O(12)
N(1)
O(21)
O(42)
O(32)
N(4)
Pt(1)
O(11)
N(2)
O(22)
Fig. 2. Fragment of the crystal structure of II. The dashed
lines show the shortest Pt···O distances (in Å).
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006

528
YUSENKO et al.
Relative intensity
1
2
3
4
5
38
40
42
44
46
48
50
2θ, deg
Fig. 3. Fragment of the X-ray diffraction pattern for a metal powder produced by the thermolysis of salt II in a mixture with ammo-
nium chloride (1 : 10 wt/wt) at 500°C under helium after washing off cobalt chloride with water: (1) observed intensities, (2) plat-
inum (a = 3.923 Å), (3) Pt Co
solid solution (a = 3.890 Å), (4) Pt Co
solid solution (a = 3.855 Å), and (5) Pt Co
0.90 0.10
0.75 0.25 0.60 0.40
solid solution (‡ = 3.795 Å).
3
[Pt(NO2)4]2– anions in the structure are paired with a
Pt···Pt distance equal to 5.282 Å (Fig. 2). The structural
units in a crystal are linked through weak hydrogen
bonds N–H···O and é(W)–H···O, equal to 2.89 and
2.96 Å, respectively. The crystal water molecules are
hydrogen bonded mainly with the cations.
We characterized the final products of thermolysis
of complex II under helium using X-ray powder dif-
fraction. After the complex was heated to 500°C, a mix-
ture of metal platinum and Co3O4 was formed. Heating
a mixture of complex II and ammonium chloride
(1 : 10 wt/wt) to the same temperature produced
cobalt(II) chloride and a polyphase metal mixture. Fig-
ure 3 shows the X-ray diffraction pattern from the pow-
der obtained after water washing of cobalt chloride.
The complex profile of each diffraction peak was
formed by reflections from pure platinum and the
Pt1 − xCox solid-solution series based on the face-cen-
tered cubic (fcc) lattice of platinum. The figure displays
an approximate model in which the reflection profile is
formed by platinum (a = 3.923 Å) and three solid solu-
tions with the parameters a1 = 3.885 Å, a2 = 3.855 Å,
and a3 = 3.790 Å. The compositions of the solid solu-
tions were estimated from the Zen rule [11] (assuming
the additivity of the volume per atom in the solid solu-
Thermal properties. Compounds I and II decom-
posed in flowing helium in the same manner, with two
well-defined exotherms at 160 and 230°C for com-
pound I and at 160 and 250°C for compound II. The
thermolysis of complex II was preceded by water loss
at 90–100°C. Dehydration was achieved under isother-
mal conditions. Heating complex II in vacuum at
100°C for 10 h dehydrated about half of the starting
amount of the salt; the salt transformed to a phase struc-
tural to compound I with the following monoclinic unit
cell parameters: a = 8.01 Å, b = 22.27 Å, c = 7.93 Å,
β = 99.4°. Further heating at this temperature decom-
posed the complex; after 3 days, the complex com-
pletely transformed to a phase with an unknown struc-
ture. The IR spectrum of this phase did not differ from
the spectrum of the starting compound, which proved
the absence of ligand rearrangement between the cation
and anion.
tion) as follows: Pt0.90Co0.10
,
Pt0.75Co0.25
,
and
Pt0.60Co0.40, respectively. We may suggest that ammo-
nium chloride reduced part of the cobalt during the
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SYNTHESIS AND CHARACTERIZATION OF [Co(NH3)5NO2][M(NO2)4]
Relative intensity
529
1
2
3
40
50
2θ, deg
Fig. 4. Fragment of the X-ray diffraction pattern for a metal powder produced by the thermolysis of salt II under a hydrogen atmo-
sphere at 450°C: (1) observed intensities, (2) Pt Co
solid solution (a = 3.870 Å), and (3) Pt Co
solid solution (a =
0.80 0.20
1
0.60 0.40
2
3.805 Å).
Relative intensity
1
2
Pd
Pd
Pd
40
60
2θ, deg
Fig. 5. Fragment of the X-ray diffraction pattern for a metal powder produced by the thermolysis of salt I under a hydrogen atmo-
sphere (1) without thermal diluent and (2) with ammonium chloride used as a thermal diluent.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006

530
YUSENKO et al.
thermolysis, and the metal cobalt formed solid solu- varying the temperature and gas ambiance, one can
tions with platinum.
determine the phase composition of the products and
the dispersivity of the resulting powders.
The thermolysis products of complex II in hydrogen
were obtained in two ways. In the first case, the com-
plex was heated to 450°C under a hydrogen atmo-
sphere, then it was cooled under the hydrogen atmo-
sphere. The final product was two fcc phases (Fig. 4)
with the cubic unit cell parameters a1 = 3.870 Å and
a2 = 3.805 Å, which corresponded to Pt0.80Co0.20 and
Pt0.60Co0.40 solid solutions, respectively. The CSD sizes
were 100–150 and 50–70 Å, respectively. In the second
case, the heating schedule was the same but ammonium
chloride was used as the thermal diluent. The X-ray dif-
fraction pattern of the product nearly coincided, in its
peak intensities and positions, with the PDF card
65-8969 for intermetallic compound CoPt. The tetrago-
nal unit cell parameters (a = 3.794 Å, c = 3.724 Å)
slightly differed from the standard values.
REFERENCES
1. Strukturbericht, Ed. by C. Hermann, O. Lohrmann, and
H. Philipp (Leipzig, 1966), Vol. 2, p. 102.
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sian].
5. Handbuch der präparativen anorganischen Chemie, Ed.
by G. Brauer (Ferdinand Enke, Stuttgart, 1981; Mir,
Moscow 1985).
The thermolysis products of salt I in flowing hydro-
gen were studied in the same manner. The final product
was a single-phase sample with the fcc unit cell param-
eter a = 3.750 Å (CSD sizes were 100–150 Å), which
corresponded to a solid solution with an approximate
composition of Pd0.45Co0.55. Heating in the presence of
a thermal diluent (ammonium chloride) yielded a solid
solution with the parameter a = 3.785 Å and the com-
position Pd0.50Co0.50. The sample also contained less
than 2 wt % of metal palladium (Fig. 5).
6. Powder Diffraction File. Alphabetical Index. Inorganic
Phases (JCPDS, ICDD, Pa, 1983).
7. G. Nolze and W. Kraus, Powder Diffraction 13 (4), 256
(1998).
8. G. M. Sheldrick, SHELX97. Release 97-1 (Univ. of Göt-
tingen, Göttingen, 1997).
9. M. A. Porai-Koshits, G. A. Kukina, and V. P. Nikolaev,
Koord. Khim. 4, 1435 (1978).
10. S. A. Gromilov, I. A. Baidina, S. P. Khranenko, et al., Zh.
Strukt. Khim. 44, 90 (2003).
Proceeding from the data above, we may infer that
the metal products of thermolysis of compounds I and
II are strongly affected by the process parameters. By
11. W. Pearson, The Crystal Chemistry and Physics of Met-
als and Alloys (Wiley, New York, 1972; Mir, Moscow,
1977).
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 4 2006