Manganese(II) complexes of 2,3,5,6-tetra-(2-pyridyl)pyrazine-Syntheses, crystal structures, spectroscopic, magnetic and catalytic properties

Article abstract of DOI:10.1016/j.poly.2013.01.015

A systematic studies on complex formation between Mn(II) ions, 2,3,5,6-tetra(2-pyridyl)pyrazine and halide or pseudohalide (N₃ ^-, NCS^- and N(CN)₂^-) ligands have been carried out and the following comp

Full text of DOI:10.1016/j.poly.2013.01.015

Polyhedron 53 (2013) 132–143
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Polyhedron
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Manganese(II) complexes of 2,3,5,6-tetra-(2-pyridyl)pyrazine – Syntheses,
crystal structures, spectroscopic, magnetic and catalytic properties
a
b
b
c
d
B. Machura a, , J. Palion , J. Mrozinski , B. Kalinska , M. Amini , M.M. Najafpour ,
⇑
´
´
R. Kruszynski e
a Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
b Faculty of Chemistry, Wroclaw University, F. Joliot-Curie 14 St., 50-383 Wrocław, Poland
c Department of Chemistry, Faculty of Science, University of Maragheh, Golshahr, P.O. Box 55181-83111731, Maragheh, Iran
d Department of Chemistry, Institute for Advanced Studies in Basic Sciences, 45195-1159 Gava Zang, Zanjan, Iran
Department of X-ray Crystallography and Crystal Chemistry, Institute of General and Ecological Chemistry, Technical University of Lodz, 116 Zeromski St., 90-924 Łódz, Poland
e
_
´
a r t i c l e i n f o
a b s t r a c t
Article history:
A systematic studies on complex formation between Mn(II) ions, 2,3,5,6-tetra(2-pyridyl)pyrazine and
halide or pseudohalide (N3ꢀ, NCSꢀ and N(CN)2ꢀ) ligands have been carried out and the following com-
Received 14 September 2012
Accepted 8 January 2013
Available online 29 January 2013
plexes [Mn2(
l-Cl)2Cl2(tppz)2] (1), [Mn2Cl2(
l-N3-
j
N1)2(tppz)2] (2), [MnCl(SCN)(tppz)(H2O)]ꢁH2O (3),
[MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4), [Mn(NO3)2(tppz)(H2O)] (5), [Mn(N3)(NO3)(tppz)(H2O)] (6),
[Mn(SCN)2(tppz)] (7) and [Mn(NO3)(dca)(tppz)]n (8) have been obtained. The compounds were
characterized by elemental analysis, IR, EPR, magnetic measurements and X-ray analysis. Two of
them (5 and 6) have been tested as catalysts in oxidation of alcohol to aldehydes/ketones using
oxone (2KHSO5ꢁKHSO4ꢁK2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and
tetra-n-butylammonium bromide as phase transfer agent under air at room temperature and as catalysts
in oxidation of sulfides to sulfoxides with UHP (urea hydrogen peroxide) as oxidant.
Keywords:
Manganese(II)
2,3,5,6-Tetra(2-pyridyl)pyrazine
X-ray structure
Magnetic properties
Catalytic activity
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
between paramagnetic centers bridged by the central pyrazine
moiety and hence separated by more than 6.4 Å [4,5]. The largest
2,3,5,6-Tetra-(2-pyridyl)pyrazine (tppz), synthesized by Good-
win and Lions in 1959, was designed as an analogue of terpyridine
but with the idea that it also might bridge central ions and form ex-
tended chain structures due to six potential donor sites [1]. In me-
tal complexes tppz forms seven distinct binding modes illustrated
in Scheme 1.
antiferromagnetic interaction has been found in the dinuclear
complexes [Cu2(tppz)(H2O)4](ClO4)4ꢁ2H2O (J = ꢀ61.1 cmꢀ1
) and
[Ni2(tppz)(H2O)6](NO3)4ꢁ2.5H2O (J = ꢀ76 cmꢀ1) [5]. Interestingly,
the relatively good efficiency of the tppz bridge in transmitting
magnetic interactions between paramagnetic centers contrasts
with much poorer ability of unsubstituted pyrazine bridges in its
metal complexes, where negligible or weak antiferromagnetic
As we can see from scheme 1, tppz binds to a metal center in a
bidentate
a
(a) or
c
(b), bis-bidentate
a
(c) or
c
(d), tris-bidentate
interactions were observed (with
J
values ranging from
(e), tridentate (f) or bis-tridentate (g) coordination mode, forming
both mono- and polynuclear complexes with interesting electronic
and magnetic properties.
ꢀ0.14 cmꢀ1 in [Ni(pyz)2Cl2] to 15.1 cmꢀ1 in Cu(pyz)2(ReO4)2)
[6,7]. In binuclear ruthenium(II) complexes, tppz bridges have been
found to mediate intermetallic electronic communication through
The rich photophysical and redox properties associated with
these complexes make them useful for analytical purposes and
probes for biologically relevant molecules such as DNA. Recently,
tppz has been examined as fluorescence sensors for series of metal
ions and off–off–on switching of fluorescence depending on step-
wise complex formation with tppz has been reported [3].
Studies on tppz metal(II) complexes have illustrated the ability
of this polydentate organic ligand to mediate magnetic interactions
the p symmetry orbitals [8]. In turn, the mononuclear complexes of
Co(II) of formula [Co(tppz)2]2+ with tppz ligands coordinated in a
tridentate coordination mode attract scientific interest due to ther-
mally induced spin crossover behaviour from a high-spin SCo = 3/2
at high temperatures to a low-spin SCo = 1/2 at lower temperatures
[9].
A search in CCDC (Cambridge Crystallographic Data Centre, Ver-
sion 5.33) database reveals only three Mn(II) complexes of tppz,
namely [Mn2(
l
-Cl)2Cl2(tppz)2] [10], [MnI(tppz)(H2O)2]IꢁH2O[11]
and [Mn(dca)(NO3)(tppz)(H2O)] [12]. This prompt us to systematic
studies on complex formation between Mn(II) ions, tppz and halide
or pseudohalide (N3ꢀ, NCSꢀ and N(CN)2ꢀ) ligands. Here, we present
⇑
Corresponding author.
E-mail addresses: basia@ich.us.edu.pl (B. Machura), jmroz@wchuwr.chem.uni.
wroc.pl (J. Mrozin´ ski), rafal.kruszynski@p.lodz.pl (R. Kruszynski).
0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.01.015

B. Machura et al. / Polyhedron 53 (2013) 132–143
133
Scheme 1.
synthesis, X-ray studies as well as spectroscopic and magnetic
properties of manganese(II) complexes [Mn2(-Cl)2Cl2(tppz)2] (1),
methods are available to effect this conversion, and continuous
attention is drawn to newer and more selective methods of oxida-
tion [14]. Recently, some metal complexes with N-donor ligands
were used as catalysts in these reactions [15].
[Mn2Cl2(l-N3-j
N1)2(tppz)2] (2), [MnCl(SCN)(tppz)(H2O)]ꢁH2O (3),
[MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4), [Mn(NO3)2(tppz)(H2O)]
(5), [Mn(N3)(NO3)(tppz)(H2O)] (6), [Mn(SCN)2(tppz)] (7) and
[Mn(NO3)(dca)(tppz)]n (8). The molecular structure of 1 have been
previously determined by Kwang [10], but the compound pre-
sented here has different conformation of the side pyridine rings
and different crystal packing as compared to the literature-known
one. Because the structural differences affect the magnetic proper-
ties, the contemporary structural data of 1 was included into study.
Two of these compounds (5 and 6) have been tested as catalysts
in oxidation of alcohol to aldehydes/ketones using oxone (2KHSO5ꢁ
KHSO4ꢁK2SO4) as an oxidant under biphasic reaction conditions
(CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase
transfer agent under air at room temperature and as catalysts in
oxidation of sulfides to sulfoxides with UHP (urea hydrogen perox-
ide) as oxidant. Selective oxidation of alcohols and sulfides, respec-
tively to aldehydes/ketones and sulfoxides is a prominent reaction
in laboratory and industrial synthetic chemistry [13]. In view of
their importance as intermediates in organic synthesis, several
2. Experimental
tppz and the other reagents used to the syntheses were com-
mercially available (POCh and Aldrich) and were used without fur-
ther purification. IR spectra were recorded on a Nicolet Magna 560
spectrometer in the spectral range 4000–400 cmꢀ1 with the sam-
ples in the form of KBr pellets.
2.1. Preparation of [Mn2(l-Cl)2Cl2(tppz)2] (1) and
[Mn(NO3)2(tppz)(H2O)] (5)
tppz was dissolved in a mixture of methanol/acetonitrile (30/
60 ml) and slowly added to methanolic solution of MnCl2ꢁ4H2O
or Mn(NO3)ꢁ4H2O, and stirred at room temperature for 12 h. The

134
B. Machura et al. / Polyhedron 53 (2013) 132–143
resulting solution was allowed to evaporate at room temperature
IR (KBr, cmꢀ1): 3394 (br)
m(O–H) 2061 (vs)
m
as(N3) 1631 (w),
and crystals of 1 and 5 were obtained after several days.
1594 (s), 1570 (sh) and 1534 (w) m(C@N) and m(C@C).
2.2.5. (7) [Mn(SCN)2(tppz)]
2.1.1. (1) [Mn2(l-Cl)2Cl2(tppz)2]
The compound was prepared by employing NH4SCN (0.10 g
1.6 mmol), Mn(NO3)ꢁ4H2O (0.2 g 0.8 mmol) and tppz (0.31 g,
0.8 mmol). Yield 75% (334 mg).
The compound was prepared by employing MnCl2ꢁ4H2O (0.2 g,
1 mmol) and tppz (0.39 g, 1 mmol). Yield 75% (390 mg).
Calc. for C48H32Cl4Mn2N12: C, 56.05; H, 3.14; N, 16.34. Found: C,
56.34; H, 3.08; N, 16.52%.
Calc. for C26H16MnN8S2: C, 55.81; H, 2.88; N, 20.03. Found: C,
55.21; H, 3.01; N, 20.69%.
IR (KBr, cmꢀ1): 1631 (w), 1594 (s), 1567 (sh) and 1536 (w)
IR (KBr, cmꢀ1): 2048 (vs)
m(C@NSCN) 1642 (w), 1588 (s), 1567
m(C@N) and m(C@C).
(sh)
m(C@N) and m(C@C).
2.1.2. (5) [Mn(NO3)2(tppz)(H2O)]
2.2.6. (8) [Mn(NO3)(dca)(tppz)]n
The compound was prepared by employing Mn(NO3)2ꢁ4H2O
(0.2 g, 0.8 mmol) and tppz (0.31 g, 0.8 mmol). Yield 70% (327 mg).
Calc. for C24H18MnN8O7: C, 49.24; H, 3.10; N, 9.38. Found: C,
49.96; H, 3.21; N, 9.81%.
The compound was prepared by employing NaN(CN)2 (0.14 g,
1.6 mmol), Mn(NO3)ꢁ4H2O (0.2 g, 0.8 mmol) and tppz (0.31 g,
0.8 mmol) Yield 70% (319 mg).
IR (KBr, cmꢀ1): 3415 (br)
and 1574 (sh) (C@N) and (C@C).
m(OH) 1666 (w), 1639 (w), 1590 (m)
Calc. for C26H16MnN10O3: C, 54.65; H, 2.82; N, 24.51. Found: C,
54.10; H, 2.92; N, 24.98%.
m
m
IR (KBr, cmꢀ1): 2310
ms(C@N) and 2172 mas
+ ms(C@N) 1590 (s),
1568 (sh) and 1537 (w)
m
(C@N) and (C@C).
m
2.2. Preparation of [Mn2Cl2(l-N3-kN1)2(tppz)2] (2), [MnCl(SCN)(tppz)
(H2O)]ꢁH2O (3) [MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4), [Mn(N3)
(NO3)(tppz)(H2O)] (6), [Mn(SCN)2(tppz)] (7) and [Mn(NO3)(dca)
(tppz)]n (8)
2.3. Crystal structures determination and refinement
The X-ray intensity data of 1–8 were collected on a Gemini A Ul-
tra diffractometer equipped with Atlas CCD detector and graphite
monochromated Mo Ka radiation (k = 0.71073 Å) at room temper-
ature. Details concerning crystal data and refinement are given in
Table 1. Lorentz, polarization and empirical absorption correction
NaN3, NH4SCN or NaN(CN)2 was dissolved in methanol and
slowly added to yellow methanol/acetonitrile solution of tppz
and MnCl2/or Mn(NO3)2, and stirred at room temperature for
12 h. The resulting solution was allowed to evaporate at room tem-
perature. Crystals, suitable for X-ray analysis, were obtained after
several days.
using spherical harmonics implemented in SCALE3 ABSPACK scaling
algorithm [16] were applied. The structures were solved by the di-
rect methods and subsequently completed by the difference Fou-
rier recycling. All the non-hydrogen atoms were refined
anisotropically using full-matrix, least-squares technique. The
hydrogen atoms were treated as ‘‘riding’’ on their parent carbon
atoms and assigned isotropic temperature factors equal 1.2 (aro-
matic) and 1.5 (water) times the value of equivalent temperature
factor of the parent atom. The methyl groups were allowed to ro-
tate about their local threefold axis. SHELXS97 and SHELXL97 [17] pro-
grams were used for all the calculations. Atomic scattering factors
were those incorporated in the computer programs. At x, ½, ½ the
compound 1 have the solvent accessible void of about 180 Å3, filled
2.2.1. (2) [Mn2Cl2(l-N3-kN1)2(tppz)2]
The compound was prepared by employing NaN3 (0.13 g,
2 mmol), MnCl2ꢁ4H2O (0.2 g, 1 mmol) and tppz (0.39 g, 1 mmol).
Yield 75% (395 mg).
Calc. for C48H32Cl2Mn2N18: C, 55.35; H, 3.10; N, 24.20. Found: C,
55.92; H, 3.16; N, 24.76%.
IR (KBr, cmꢀ1): 2065 (vs)
mas(N3) 1639 (w), 1590 (s), 1569 (sh)
and 1536 (w) m(C@N) and m(C@C).
with the continuous electron density not larger than 0.377 e Åꢀ3
.
2.2.2. (3) [MnCl(SCN)(tppz)(H2O)]ꢁH2O
The compound was prepared by employing NH4SCN (0.15 g
2 mmol), MnCl2ꢁ4H2O (0.2 g 1 mmol) and tppz (0.39 g, 1 mmol)
Yield 75% (434 mg).
Because such density do not show any clear maximum it can be
stated that above mentioned solvent accessible void is filled with
the diffused solvent (multiple, differently disordered solvent mol-
ecules). Refinement of the model which does not comprise the dif-
fused solvent leads to the satisfactory and reasonable structural
parameters (Table 1). The compound 4 contains build up into the
inner coordination sphere the disorder solvent molecules (water/
methanol). These solvents exist almost alternately in the crystal
net molecules and the oxygen atoms of both molecules occupy al-
most equivalent places in the asymmetric unit.
Calc. for C25H20ClMnN7O2S: C, 52.41; H, 3.52; N, 17.11. Found:
C, 51.99; H, 3.76; N, 17.81.
IR (KBr, cmꢀ1): 3391 (br)
m
(O–H) 2063 (vs)
m(C@NSCN) 1649 (m),
1598 (s), 1569 (sh) and 1539 (w) (C@N) and
m
m(C@C).
2.2.3. (4) [MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47
]
The compound was prepared by employing NaN(CN)2 (0.18 g,
2 mmol), MnCl2ꢁ4H2O (0.2 g, 1 mmol) and tppz (0.39 g, 1 mmol).
Yield 65% (374 mg).
2.4. Magnetic measurement and EPR spectra
Calc. for C26.47H18.94ClMnN9O: C, 55.82; H, 3.35; N, 22.14.
Found: C, 55.49; H, 3.42; N, 22.65%.
Variable-temperature magnetic measurements of polycrystal-
line samples were carried out with a Quantum Design SQUID mag-
netometer (MPMSXL-5-type) at a magnetic field of 0.5 T over the
temperature range 1.8–300 K. Correction are based on subtracting
the sample-holder signal, contribution vDia estimated from Pascal
IR (KBr, cmꢀ1): 3395 (m), 3324 (m) and 3209 (m)
m
(O–H), 2299,
s(C@) 1620 (m), 1601 (s), 1578 (s) and
m(C@C).
2228
1540 (m)
m
s(C@ and 2176 mas
(C@N) and
+ m
m
2.2.4. (6) [Mn(N3)(NO3)(tppz)(H2O)]
constants [18]. The effective magnetic moment was calculated
1=2
The compound was prepared by employing NaN3 (0.10 g,
1.6 mmol), Mn(NO3)2ꢁ4H2O (0.2 g 1 mmol) and tppz (0.31 g,
0.8 mmol). Yield 65% (293 mg).
from the equation: leff ¼ 2:83ð
v
MTÞ
(B.M.). Magnetization ver-
sus magnetic field measurements were carried out at 2 K in the
magnetic field range 0–5 T.
Calc. for C24H18MnN10O4: C, 50.98; H, 3.21; N, 9.72. Found: C,
50.17; H, 3.30; N, 9.99%.
EPR spectra were recorded at room temperature and 77 K on a
Brüker ESP 300 spectrometer operating at X-band, equipped with

Table 1
Crystal data and structure refinement for 1–8.
1
2
3
4
5
6
7
8
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C
48H32Cl4Mn2N12
C48H32Cl2Mn2N18
1041.70
293.0(2)
0.71073
triclinic
C25H20ClMnN7O2S
572.93
293.0(2)
0.71073
monoclinic
P21/n
C26.47H18.94ClMnN9O
569.51
293.0(2)
0.71073
monoclinic
P21/c
C24H18MnN8O7
585.40
293.0(2)
0.71073
monoclinic
P21/n
C24H18MnN10O4
565.42
293.0(2)
0.71073
monoclinic
P21/c
C26H16MnN8S2
559.53
293.0(2)
0.71073
monoclinic
P21/n
C26H16MnN10O3
571.43
293.0(2)
0.71073
monoclinic
P21/n
1028.54
293.0(2)
0.71073
triclinic
ꢀ
ꢀ
P1
P1
9.3470(5)
10.4400(6)
13.4185(8)
72.537(5)
78.073(5)
81.714(5)
1217.36(12)
1
8.9184(4)
11.0500(5
13.0981(6)
107.895(4)
96.332(3)
105.086(4)
1160.31(9)
1
17.1955(14)
7.3436(6)
21.7739(18)
15.8314(8)
7.3101(5)
22.4617(9)
14.3966(5)
9.5914(4)
18.6066(7)
14.0217(5)
9.7158(4)
22.4628(8)
15.8687(6)
7.3574(2)
22.3087(8)
9.3542(5)
8.7838(3)
31.2293(14)
b (Å)
c (Å)
a
(°)
b (°)
(°)
110.744(9)
99.942(4)
94.362(3)
123.700(3)
108.884(4)
97.324(4)
c
Volume (Å3)
Z
2571.3(4)
4
2560.4(2)
4
2561.82(17)
4
2545.91(17)
4
2464.41(15)
4
2545.0(2)
4
Density (calculated)
1.403
1.491
1.480
1.477
1.518
1.475
1.508
1.491
(Mg/m3)
Absorption coefficient 0.785
(mmꢀ1
F(000)
0.717
530
0.736
1172
0.660
1163
0.576
1196
0.571
1156
0.738
1140
0.569
1164
)
522
Crystal size (mm)
h range for data
collection (°)
0.025 ꢂ 0.109 ꢂ 0.261 0.025 ꢂ 0.067 ꢂ 0.242 0.255 ꢂ 0.135 ꢂ 0.090 0.017 ꢂ 0.072 ꢂ 0.185 0.028 ꢂ 0.049 ꢂ 0.170 0.047 ꢂ 0.085 ꢂ 0.102 0.074 ꢂ 0.160 ꢂ 0.254 0.031 ꢂ 0.106 ꢂ 0.250
3.47–25.00
3.44–25.00
3.39–25.05
3.45–25.05
3.44–25.05
3.44–25.05
3.40–25.00
3.51–25.05
Index ranges
ꢀ11 6 h 6 10
ꢀ12 6 k 6 12
ꢀ15 6 l 6 14
8285
ꢀ10 6 h 6 10
ꢀ13 6 k 6 12
ꢀ15 6 l 6 15
8814
ꢀ20 6 h 6 20
ꢀ8 6 k 6 8
ꢀ18 6 h 6 18
ꢀ7 6 k 6 8
ꢀ17 6 h 6 17
ꢀ11 6 k 6 10
ꢀ22 6 l 6 22
14432
ꢀ16 6 h 6 16
ꢀ11 6 k 6 11
ꢀ26 6 l 6 26
13646
ꢀ18 6 h 6 18
ꢀ8 6 k 6 8
ꢀ9 6 h 6 11
ꢀ10 6 k 6 10
ꢀ37 6 l 6 29
11263
ꢀ25 6 l 6 25
ꢀ26 6 l 6 25
ꢀ20 6 l 6 26
Reflections collected
Independent
reflections
14670
4546 (Rint = 0.0425)
11993
4525 (Rint = 0.0426)
10633
4327 (Rint = 0.0214)
4273 (Rint = 0.0354)
4077 (Rint = 0.0326)
4532 (Rint = 0.0523)
4512 (Rint = 0.0582)
4503 (Rint = 0.0312)
Completeness to 2h
(%)
99.7
99.7
99.8
99.8
99.7
99.8
99.7
99.7
Min. and max. transm. 0.812 and 1.000
0.903 and 1.000
4077/0/316
0.712 and 1.000
4546/7/334
0.772 and 1.000
4525/0/362
0.856 and 1.000
4532/0/361
0.927 and 1.000
4512/0/354
0.766 and 1.000
4327/0/334
0.937 and 1.000
4503/0/361
Data/restraints/
parameters
4273/0/298
Goodness-of-fit on F2
Final R indices
0.941
1.028
1.072
1.028
0.980
1.110
1.045
1.036
R1 = 0.0478
wR2 = 0.1128
R1 = 0.0764
wR2 = 0.1227
0.377 and ꢀ0.354
R1 = 0.0446
wR2 = 0.1046
R1 = 0.0701
wR2 = 0.1144
0.440 and ꢀ0.472
R1 = 0.0561
wR2 = 0.1499
R1 = 0.0737
wR2 = 0.1629
0.743 and ꢀ0.460
R1 = 0.0436
wR2 = 0.0958
R1 = 0.0841
wR2 = 0.1055
0.420 and ꢀ0.259
R1 = 0.0498
wR2 = 0.1055
R1 = 0.0864
wR2 = 0.1155
0.654 and ꢀ0.365
R1 = 0.0461
wR2 = 0.1330
R1 = 0.0828
wR2 = 0.1422
1.039 and ꢀ0.242
R1 = 0.0340
wR2 = 0.0886
R1 = 0.0490
wR2 = 0.0917
0.407 and ꢀ0.587
R1 = 0.0387
wR2 = 0.0883
R1 = 0.0562
wR2 = 0.0943
0.655 and ꢀ0.382
[I > 2r(I)]
R indices (all data)
Largest diff. peak and
hole (e Åꢀ3
)

136
B. Machura et al. / Polyhedron 53 (2013) 132–143
an ER 035M Brüker NMR gaussmeter and HP 5350B Hewlett–Pack-
ard microwave frequency counter.
The intra- and intermolecular contacts [20] detected in the
structures 2–8 are collected in Table S1. The compound 1 does
not show any interaction which can be classified even as weak
hydrogen bond, however, due to existence of diffused solvent in
the crystal structure, the intermolecular contacts scheme is incom-
plete and some bonding interactions between the solvent and
complex molecules eventually may exist. It can be postulated that
formation of the hydrogen bond between the solvent and complex
molecules leads to stabilization of the solvent molecules positions
in the crystal structure, thus the presence of diffused solvent may
indicated a lack of the intermolecular interactions between the sol-
vent and complex molecules. The molecules of compounds 2, 7 and
8 are interconnected only by weak C–Hꢁ ꢁ ꢁD hydrogen bonds
(Table S1), respectively, to the chains extending along the crystal-
lographic [011] axis, to the dimers and to the ribbons exiting along
the crystallographic [010] axis and perpendicular to the crystallo-
2.5. Catalytic studies
2.5.1. General procedure in oxidation of alcohol
In a typical experiment, a solution of Oxone (0.2 mmol) in H2O
(5 ml) at room temperature was added to a solution of alcohol
(0.2 mmol), tetra-n-butylammonium bromide, (0.1 mmol), and
catalyst (0.01 mmol), in CH2Cl2 (1 mL), and the biphasic mixture
stirred vigorously. Formation of products and consumption of
substrates were monitored by gas chromatography. The identity
of products was determined by comparison with authentic
samples using gas–liquid chromatography. Oxidation products
yields based on the oxidant, were quantified by comparison with
chlorobenzene.
ꢀ
graphic (013) plane. The complex molecules of 3 are connected by
O–Hꢁ ꢁ ꢁCl medium strength hydrogen bonds to the chains extend-
ing along crystallographic [010] axis and described C(4) graph.
The unitary graph set is formed by these C(4) motifs and additional
D motifs of O–Hꢁ ꢁ ꢁO hydrogen bonds. The weak C–Hꢁ ꢁ ꢁCl hydrogen
bonds (Table S1) expands above mentioned chins to the layers
2.5.2. General procedure for sulfide oxidation
To a solution of sulfide (0.2 mmol), imidazole (0.1 mmol) as ax-
ial ligand, chlorobenzene (0.2 mmol) as internal standard and cat-
alyst (0.01 mmol) in a (1:1) mixture of CH3OH/CH2Cl2 (1 ml) was
added UHP (0.4 mmol) as oxidant. The mixture was stirred at room
temperature and the progress of the reaction was monitored by GC,
by removing small samples of the reaction mixture. To establish
the identity of the products unequivocally, the retention times
and spectral data were compared to those of commercially avail-
able compounds.
ꢀ
propagating along crystallographic (101) plane, and weak C–
Hꢁ ꢁ ꢁS hydrogen bonds (Table S1) extents these layers to the 3D
supramolecular network. The molecules of 4 are linked to hydro-
gen bonded dimers by O–Hꢁ ꢁ ꢁN interactions forming N1C22(16)
motifs. The presence of the weak C–Hꢁ ꢁ ꢁCl hydrogen bonds lead
to formation of the 3D network in 4. The medium strength O–
Hꢁ ꢁ ꢁA hydrogen bonds link the molecules of 5 to the chains extend-
ing along crystallographic [010] axis and described by
C(4)C(6)C(8) basic unitary graph set motifs. The weak C–Hꢁ ꢁ ꢁO
hydrogen bonds expands these chains to the 3D supramolecular
network. In compound 6, similarly to the 5, the O–Hꢁ ꢁ ꢁN hydrogen
bonds extents molecules to the chains located along crystallo-
graphic [010] axis but they forms the C(4)C(5)C(8) basic unitary
graph set. Additionally the weak C–Hꢁ ꢁ ꢁO hydrogen bonds present
in 6 link above mentioned chain to the plane expanding along the
crystallographic (001) plane. Additionally the molecules of the
compounds 2–6 and 8 are internally liked by the by the weak C–
Hꢁ ꢁ ꢁA intramolecular bonds.
3. Results and discussion
3.1. Preparation and infrared data
The preparations of complexes 1–8 were carried out in a mix-
ture methanol–acetonitrile in molar ratio of manganese(II) ions
to ligand equal 1:1, and two manganese(II) salts (MnCl2 4H2O
and Mn(NO3)2 4H2O) were used for the syntheses. The reaction
of tppz with MnCl2 yields [Mn2(l-Cl)2Cl2(tppz)2] (1), while
Mn(NO3)2 reacts with tppz to form [Mn(NO3)2(tppz)(H2O)] (5).
Interestingly, the choice of manganese(II) salt turned out to be
crucial in complex formation with tppz and pseudohalide ligands.
MnCl2 reacts with tppz and NH4SCN, NaN3 or NaN(CN)2 to give
3.3. [Mn2(-Cl)2Cl2(tppz)2] (1) and [Mn2Cl2(-N3-N1)2(tppz)2] (2)
[MnCl(SCN)(tppz)(H2O)]ꢁH2O (3), [Mn2Cl2(
l
-N3-kN1)2(tppz)2] (2)
ꢀ
Compounds 1 and 2 crystallize in the triclinic space group P1.
and [MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47
]
(4), respectively,
Perspective view of the molecule 2 with the labeling of the atoms
are depicted in Fig. 1, and the relevant bond lengths of 1 and 2 are
collected in Table 2. The molecular structure of 1 and detailed
structural parameters of 1 and 2 were included in Supplementary
materials (Fig. S1, Tables S2 and S3). The dinuclear complexes 1
and 2 result from the pairing of two mononuclear units related
by a crystallographic center of inversion. In 1 the manganese(II)
centers are doubly bridged by chloride ions, whereas the Mn(II)
of 2 are doubly linked by end-on (EO) azide groups.
In both dimers, the four atoms involved in bridging form a per-
fect plane due to the existence of an inversion center. The resulting
intradinuclear Mnꢁ ꢁ ꢁMn separation of 3.859 Å in 1 and 3.553 Å in 2
falls in the range reported for the related Mn(II) dimers [21]. Sim-
ilarly, the bridging angles Mn(1)–Cl(2)–Mn(1)#1 (96.59(3)°) and
Mn(1)–N(99)–Mn(1)#1 (104.91(11)°) are in good agreement with
whereas the reactions of Mn(NO3)2 with tppz and NH4SCN, NaN3
or NaN(CN)2 yield [Mn(SCN)2(tppz)] (7), [Mn(N3)(NO3)(tppz)(H2-
O)] (6) and [Mn(NO3)(dca)(tppz)]n (8).
In high frequency region the IR spectra of 3, 4, 5 and 6 show
broad and strong absorptions centered at 3391 cmꢀ1 for 3, 3395,
3324 and 3209 cmꢀ1 for 4, 3415 cmꢀ1 for 5 and 3394 cmꢀ1 for 6,
assignable to the O–H stretching water molecules. Intense absorp-
tions associated with the stretching modes of the pseudohalide
ions occur at 2065 cmꢀ1 for 2, 2063 cmꢀ1 for 3, 2299, 2228 and
2176 cmꢀ1 for 4, 2061 cmꢀ1 for 6, 2048 cmꢀ1 for 7, 2310 and
2172 cmꢀ1 for 8. Peaks revealing the presence of tppz occur in
the ranges 3100–2880 cmꢀ1 (aromatic C–H stretching vibrations),
1600–1530 cmꢀ1
(C@N) and
1000 cmꢀ1 (C–N) vibrations) and 800–700 cmꢀ1 (aro-
C–C) + m
(m
m(C@C) stretches), 1480–
(m
matic C–H deformation vibrations). In the case of 5, 6 and 8 the re-
gionꢀ1480–1000 cmꢀ1 is partially obscured by the strong nitrate
NO3 stretching modes [19].
data reported in the literature, for example in [MnCl(l-
Cl)(mpbpa)]2 the Mn(1)–Cl(1)–Mn(1)i angle equals 94.426(19)°
[21a] and in [Mn(terpy)(N3)2] 2H2O the Mn– N4–Mni angle is
104.6(1)°) [21e]. The two Mn2Cl bridging bond lengths in 1 are sig-
nificantly different (2.4227(10) Å and 2.7391 Å). A similar trend is
observed in 2, where Mn–N corresponding to the bridging azide
groups are equal 2.161(2) and 2.319(3) Å.
3.2. Crystal structure analysis
The crystallographic data of 1–8 are summarized in Table 1.

B. Machura et al. / Polyhedron 53 (2013) 132–143
137
Fig. 1. The molecular structure of 2. Displacement ellipsoids are drawn at 50% probability.
Table 2
The relevant bond lengths of 1–8.
1
2
3
4
5
6
7
8
Mn–Npz
2.243(3)
2.255(3)
2.265(3)
2.4461(10)
2.7391(10)
2.275(2)
2.254(2)
2.275(3)
2.4266(11)
2.224(2)
2.243(3)
2.235(3)
2.5009(13)
2.248(2)
2.256(2)
2.226(2)
2.4763(11)
2.267(2)
2.316(2)
2.295(2)
2.283(2)
2.327(3)
2.293(3)
2.2455(17)
2.2423(17)
2.2432(18)
2.3096(18)
2.2701(19)
2.3212(19)
Mn–N(3)py
Mn–N(4)py
Mn–Cl(1)
Mn–Cl(2)
Mn–Nazide
Mn–N(99)SCN
Mn–N(98)SCN
Mn–Owater
Mn–OMeOH
Mn–O(1)nitrate
Mn–O(2)nitrate
Mn–O(4)nitrate
Mn–N(99)dca
Mn–N(97)dca
2.161(2)
2.200(3)
2.183(2)
ꢀ
ꢀ
2.060(3)
2.465(4)
2.156(2)
2.032(2)
2.294(13)
2.19(2)
2.160(2)
2.367(2)
2.295(2)
2.317(3)
2.372(2)
2.238(3)
2.298(3)
2.407(3)
2.108(3)
2.201(2)
2.2292(19)
Each Mn(II) ion in the two dimers exhibits a distorted octahe-
dral coordination sphere. The main source of distortion of the
metal surrounding comes from the bites taken by tppz ligand
The tppz ligand is appreciably twisted, dihedral angles between
the pyrazine ring and each of the pyridyl rings are equal
41.35(12)°, 31.95(14)°, 30.03(15)° and 21.74(16)
° in 1 and
equal 71.04(9)° and 71.48(10)° for
1
and 70.11(8)° and
51.85(10)°, 29.53(12)°, 26.77(15)° and 18.57(17)° in 2. The pyra-
zine ring itself is puckered with maximum atomic deviations from
a best mean plane being 0.1053 Å at C(4) in 1 and 0.0995 Å at C(2)
in 2. The torsion angles N1–C1–C2–N2 and N2–C3–C4–N1 are
ꢀ18.51(41)° and 16.83(39)° in 1 and, and the dihedral angle be-
tween the two C–N–C planes of the pyrazine ring is 10.07(46)° in
1 and 5.18(33)° in 2. The non-planarity of the pyrazine ring is
unexceptional. It has been reported for the related structures
[2b,c,4,6,11,23,24], and the factor responsible for destabilizing
the planar geometry of the pyrazine ring has a pure electronic ori-
gin [25].
71.56(8)° for 2. In complex 1 the Mn(1) ions are coordinated
by three N atoms from the tppz ligand and three chloride ligands
giving a six-coordinate mer-N3Cl3 donor set. In 2 three nitrogen
atoms of the tppz ligand and one nitrogen atom of end-on azido
ligand act as the equatorial plane, while the nitrogen atom of the
second end-on azido ligand and chloride ion situate in the axial
positions.
The Mn–N bond lengths, ranging from 2.243(3) Å to 2.319(3) Å,
and Mn–Cl distances, from 2.4227(10) to 2.7391(10) Å, fall within
the normal range in dimers incorporating six-coordinate manga-
nese(II) ions [21,22]. In 1, the bond distance of Mn(II) to the middle
nitrogen N(1) is shorter than Mn(1)–N(3) and Mn(1)–N(4) dis-
tances, which is usually observed in tppz-like ligands [2]. The
shortness of Mn–Npyrazine distance within the tppz unit is attributed
to a more efficient overlap of the metal t2g orbitals with the p⁄ orbi-
tals of the central pyrazine ring compared to the distal pyridyl
groups. This trend is not observed in complex 2, probably due to
a trans effect of the azide group.
3.4. [MnCl(SCN)(tppz)(H2O)]ꢁH2O (3) and
[MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4)
A perspective view of the molecule 3 with the labeling of the
atoms are depicted in Fig. 2, and the relevant bond lengths and an-
gles of the molecule 3 and 4 are collected in Table 2. The molecular
structure of 4 and detailed structural parameters of 3 and 4 were

138
B. Machura et al. / Polyhedron 53 (2013) 132–143
Fig. 2. The molecular structure of 3. Displacement ellipsoids are drawn at 50% probability.
included in Supplementary materials (Fig. S2, Tables S4 and S5). In
both compounds the metal center is six coordinate and shows a
distorted octahedral geometry. The tridentate tppz ligand and
pseudohalide ion (quasi-linear (178.5(4)°) terminal thiocyanate
ion in 3 and dca anion in 4) constitute the equatorial plane, while
axial positions are occupied by chloride ion and solvent molecule.
The Mn–N bond lengths of 3 follow a decreasing order for pyr-
idyl (2.243(3) and 2.234(3) Å), pyrazine (2.224(3) Å) and thiocya-
nate (2.060(3) Å) donors, indicating the expected variation in
coordinating ability. The anionic NCS N-donors bind most strongly,
followed by the two neutral nitrogen donors from the heterocycles.
Similar to the previous structures, there is twisting between the
pyrazine and pyridyl rings. The uncoordinated pyridine rings are
inclined toward the pyrazine ring by 39.13(9)°, 27.40(8)° in 3
and 39.26(8)°, 28.41(6)° in 4, and the dihedral angles between
the pyrazine ring and coordinated pyridyl rings are equal
17.59(13)° and 23.22(13)° in 3 and 19.74(12)° and 23.18(11)° in
4. The individual pyridyl rings are planar within experimental er-
rors, while the pyrazine ring is significantly puckered (with maxi-
constituted by three N atoms of tpzz ligand and two oxygen atoms
from the bidentate nitrate ligand, but axial positions are occupied
by the oxygen atom belonging to the water molecule and nitrogen
atom of the azide group. A rare heptacoordinated geometry of
Mn(II) ions in 5 and 6 seems to be govern by simultaneous exis-
tence of bidentate nitrate ligand leading to the formation of four-
membered chelate ring and tridentate tppz ligand forming with
the central ion two five-membered chelate rings. The deviation
from ideal pentagonal bipyramidal geometry, clearly indicated by
bond angles in the equatorial plane, comes from the bites taken
by the nitrate ion (54.19(8) in 5 and 54.01(8) in 6) and tppz ligands
(70.41(9) and 70.45(9) in 5 and 69.75(9) and 70.95(9) in 6). In turn,
the bond angles N(3)–Mn(1)–O(1) (81.60(11)°) and N(4)–Mn(1)–
O(2) (85.04(11)°) are considerably greater than ideal for pentago-
nal bipyramidal geometry value 72°.
The individual pyridyl rings are planar within experimental er-
rors, while the pyrazine ring is significantly puckered, with maxi-
mum atomic deviations from
a best mean plane being
0.1105(20) Å at C(2) in 5 and 0.1112(21) Å at C(2) in 6). The dihe-
dral angles between the pyrazine and uncoordinated pyridyl rings
are 38.86(13)° and 34.50(14)° in 5 and 38.60(16)° and 36.06(17)°
in 6, whereas the coordinated pyridine rings are inclined toward
the pyrazine ring by 20.16(10) and 25.86(9) in 5 and 18.86(11)
and 26.74(10) in 6. The Mn–N bonds involving the tppz ligand vary
from 2.267(2) to 2.327(3) Å, and the Mn–N distance for the coordi-
nated pyrazine is slightly shorter in comparison with Mn–Npyridine
(Tables S6 and S7).
According to the criteria introduced by Kleywegtꢀal. [26] for
determining nitrate binding mode (Table S8) the NO3 group of 5
coordinates to central ion in an symmetric bidentate fashion. For
complex 6 two coordination modes have been confirmed. The ni-
mum atomic deviations from
a best mean plane being
0.1113(22) Å at C(4)) in 3 and 0.1141(19) Å at C(2)) in 4.
3.5. [Mn(NO3)2(tppz)(H2O)] (5) and [Mn(N3)(NO3)2(tppz)(H2O)] (6)
The manganese(II) ions of 5 and 6 are heptacoordinated with
coordination polyhedron close to the pentagonal bipyramid
(Figs. S3 and S4). In 5 the heptacoordination is achieved by means
of three N atoms from the tppz ligand and two oxygen atoms from
the bidentate nitrate ligand, which determine the equatorial plane,
and two oxygen atoms, from the water molecule and monodentate
nitrate group, in axial positions. The equatorial plane of 6 is also

B. Machura et al. / Polyhedron 53 (2013) 132–143
139
trate group occupying the axial positionꢀbounds to the central ion
in a monodentate mode, whereas NO3 in the equatorial plane
coordinates in symmetric bidentate fashion.
ported for [Mn(dpka)2(NCS)2]ꢁ½H2O (\Mn–N–C: 157.95(11)° and
139.20(9)°) [28], [Cu(NCS)2(C6H8N2)2] (\Cu–N–C: 127.49(10)°)
[29] and [Cu(bedmpza)(NCS)2] (\Cu–N–C: 140.75(10)° and
173.44(11)°) [30].
3.6. [Mn(SCN)2(tppz)] (7)
The molecular structure of 7 with the labeling of the atoms is
depicted in Fig. S5, and the selected bond lengths and angles are
collected in Table S9. The manganese(II) ion is five-coordinate by
three N atoms of tppz ligand and two atoms of thiocyanate ions
and shows square-based pyramidal geometry (SP). The equatorial
plane of manganese(II), defined by three tppz nitrogen atoms and
one nitrogen atom of the thiocyanate group, has a slight tetrahe-
dral distortion and the metal atom is displaced by 0.317(1) Å from
this plane in the direction of the apical position, occupying by the
nitrogen atom of the second SCNꢀ ion. As in the aforementioned
structures, the tppz ligand is appreciably twisted, the coordinated
pyridine rings are inclined toward the central pyrazine by
24.89(8)° and 29.83(7)°, and dihedral angles between the pyrazine
and uncoordinated pyridyl rings are 46.58(7)° and 56.78(5)°. Inter-
estingly, the pyrazine ring in 7 is flat within experimental error
(maximum atomic deviation at C(2) equals to 0.0221(14) Å).
The Mn–N, ranging from 2.032(2) to 2.4555(17) Å, are consis-
tent with the values observed in other penta-coordinated mononu-
clear manganese(II) complexes [27]. The Mn–N bond length is
shortest for thiocyanate nitrogens, indicating their stronger coordi-
nation than the pyridyl and pyrazine nitrogens of tppz ligand. Sim-
ilar to the complex 2, the bond distance of Mn(II) to the middle
nitrogen N(1) is slightly longer than Mn(1)–N(3) and Mn(1)–N(4)
distances, which is probably due to a trans effect of the thiocyanate
group. The NCS groups are quasilinear with N–C–S bond angle of
178.7(3)° and 179.5(2)° and are bonded to the metal ion through
an angle of 165.5(2)° and 137.2(2)°, respectively. The bent coordi-
nation is rarer compared to the linear one. Previously, it was re-
3.7. [Mn(NO3)(dca)(tppz)]n (8)
The structure 8 consists of neutral [Mn(NO3)(dca)(tppz)] mole-
cules linked by a single end-to-end dicyanamido group to an infi-
nite one-dimensional zig-zag chain propagated along the [010]
direction (Fig. 3).
The dicyanamide ligand is angular with a C(99)–N(97)–C(98)
angle of 126.8(3)° and two nearly linear N–C–N units with angle
of 170.3(3)°. The intrachain Mnꢁ ꢁ ꢁMn separation of 8.784 Å falls
in the range reported for the Mn(II) coordination polymers based
on
l1,5–N(CN)2 bridges, e.g. {[Mn(azpy)2(dca)(H2O)2]-(ClO4)(-
azpy)(H2O)2}n (8.425 Å) [31a] Mn[N(CN)2]2(H2O)2(2,5-me2pyz)2]
(8.425 Å) [31b]. Each manganese center is seven-coordinated by
three N atoms from the tppz ligand, two oxygen atoms of the ni-
trate ligand and two nitrogen atoms belonging to
l1,5-bridged
dca. The coordination polyhedron of Mn(II) ions is best described
as pentagonal bipyramid with the equatorial plane being defined
by nitrogen atoms of tppz and nitrate oxygen donors. Similarly to
the mononuclear complexes (5 and 6), the nitrate group coordi-
nates in
a symmetric bidentate mode to the central ion
(Table S8). The tppz ligand is significantly twisted. The pyrazine
ring is puckered with maximum atomic deviations from a best
mean plane being 0.0644(15) Å at C(4), and the dihedral angles be-
tween the pyrazine ring and each of the pyridyl rings are equal
27.00(9)°, 25.83(10)°, 44.64(11)° and 73.76(6)°. The coordination
bond lengths and angles, reported in Table S10, are not unexcep-
tional and correlate well with the values discussed for structures
1–7 and given for the related complexes [Mn(NO3)(dca)(tppz)(H2-
Fig. 3. The one-dimensional coordination chain of 8.

140
B. Machura et al. / Polyhedron 53 (2013) 132–143
O)] [32a], [Mn(CH3COO)(dca)(tppz)(H2O)]ꢁ(H2O)2 [32b] and
bridges cause a larger distortion than chloride ions. In turn, analy-
sis of Fig. 9 reveals that calculated shape measures for coordination
sphere of the structures 1–4 do not appear along the Bailar path.
Such deviation is typical for six-coordinated complexes incorporat-
ing polydentate ligands with small bite angles.
[Mn(dca)(NO3)(terpy)]n [32c].
3.8. Continuous shape measures (CShM)
Manganese(II) ions of the complexes 5, 6 and 8 are seven-coor-
dinated and their geometries were referred to three commonly se-
ven-vertexes polyhedra: pentagonal bipyramid (PBPY), capped
octahedron (COC) and capped trigonal prism (CTP). The CShM of
manganese(II) ions in compounds 5, 6 and 7 revealed that their
geometry is closer to pentagonal bipyramid (PBPY) than to the
other seven-vertexes polyhedron (Table S11). The distances to
the capped octahedron (COC) and capped trigonal prism (CTP)
are much larger than to the PBPY. Generally, it is assumed that
shape measures of less than 1.0 indicate minor distortions from
the reference shape values of up to 3.0 units indicate important
distortions, but the reference shape provides still a good stereo-
chemical description.
The distortion of the coordination sphere of the Mn(II) ions in
1–8 from ideal polyhedra has been calculated using the SHAPE pro-
gram [33] based on continuous shape measures (CShM) concept.
CShM allows to determine a distance between the real metal envi-
ronment and ideal polyhedron. Mathematically CShM of the origi-
nal structure (Q) is a normalized root-mean-square deviation from
the referenced structure with the desired symmetry (P) and it is
expressed by Eq. (1):
"
#
P
n
2
~
~
i¼1jqi ꢀ pij
SQ ðPÞ ¼ min
ꢂ 100
ð1Þ
P
n
2
~
~
i¼1jqi ꢀ q0j
~
where, qi are N vectors that contain the 3N Cartesian coordinates of
Two ideal shapes, the trigonal bipyramid (TBP) of D3h symme-
try, and the square pyramid (SPY) of C4v symmetry, were taken into
account in continuous shape measures for geometry of the penta-
coordinated metal center in 7. The CShM values (Table S11) indi-
cate the predominance of square-based pyramidal (SP) geometry
of the manganese(II) ion in structure 7 and well correlate with
~
the problem structure Q, and pi contain the coordinates of the ideal
~
polyhedron P and qi is the position vector of the geometric center
that is chosen to be the same for the two polyhedra [33,34]. The
minimum is taken for all possible relative orientations in space, iso-
tropic scaling, and for all possible pairings of the vertexes of the
problem and reference polyhedra. The value SQ(P) tends to zero,
when considered polyhedron Q is close to ideal one [21g]. The max-
imum allowed value SQ(P) is 100, although in practice the values
found for severely distorted chemical structures are very rarely lar-
ger than 40.
the value of angular parameter
s = 0.36 also describing the struc-
ture 7 as a distorted square pyramid [36].
3.9. Magnetic properties and EPR spectra
The results of shape measurements for Mn(II) ions in the exam-
ined structures are summarized in Table S11.
The values
range 10–300 K are near constant. The slight decrease of the value
MT at the lowest temperatures range (1.8–10 K) is caused by
occurrence of a very weak antiferromagnetic interactions between
Mn(II) centers in the crystal lattice. All magnetic data are presented
in Table 3.
The variation of the magnetization M versus the magnetic field
H have been measured for all complexes at 2 K indicates linear
relation to ꢃ1 T and than continues Brillouin function. All these
data confirms presence of spin S = 5/2 and a small lowering values
of magnetic moment of manganese(II) centers. The EPR parameters
of powdered spectra of all compounds are presented in the
Table S12.
For monometallic complexes the magnetic data were fitted
using the susceptibility equation for S = 5/2 (Eq. (2)). To elucidate
the significance of exchange between manganese(II) ions in the
crystal lattices, a molecular field correction term [37] was also in-
cluded (Eq. (3)).
vMT of monometallic complexes in the temperature
Metal centers of compounds 1–4 present a six-coordinated
environment and their geometries were referred to two ideal poly-
hedra: octahedron (Oh) and trigonal prism (TPR). The most charac-
teristic distortion of these systems is the Bailar trigonal twist,
which leading from perfect octahedron to perfect trigonal prism
and results from rotating by 60° two opposite faces of the octahe-
dron around their C3 axis [35]. In case when only two ideal polyhe-
dra are taken into consideration (as for 1–4 octahedron and
trigonal prism), each distortion can be represented by specific scat-
terplot in two-dimensional space defined by the two symmetry
measures SQ(Oh) and SQ(TRP). This scatterplot is called a shape
map [34]. Fig. S6 shows the octahedron–trigonal pathway and in-
cludes the calculated shape measures for coordination sphere of
the experimental structures 1–4. For all compounds 1–4, S(Oh) is
lower than value 4.42 corresponding to the intermediate geometry
(with h = 30°) being isosymmetric with respect to the octahedron
and the trigonal prism. Therefore, the structures 1–4 are closer to
an octahedron than to a trigonal prism and can be best described
as a distorted octahedron. Dimers 1 and 2 are more distorted in
comparison with mononuclear complexes 3 and 4, and azide
v
Nb2g2
3kT
vM
¼
SðS þ 1Þ
ð2Þ
Table 3
Magnetic parameters and magnetization data for complexes 1–8.
vdia ꢂ106
Curie constantb
C
Weiss constant h (K)
Effective magnetic moments lB (B.M.)
Magnetizationc
(B.M.)
a
b
Compound
(cm3 molꢀ1
)
(cm3 K molꢀ1
)
T = 1.8 K
T = 300 K
[Mn2(
[Mn2Cl2(
[MnCl(SCN)(tppz)(H2O)]ꢁH2O (3)
[Mn(NO3)2(tppz)(H2O)] (5)
[Mn(N3)(NO3)2(tppz)(H2O)] (6)
[Mn(SCN)2(tppz)] (7)
l
-Cl)2Cl2(tppz)2] (1)
1.1-N3)2(tppz)2] (2)
ꢀ290
ꢀ391
ꢀ273
ꢀ286
ꢀ219
ꢀ303
ꢀ251
4.21
4.10
4.35
4.34
3.94
4.28
4.33
0.0
ꢀ0.4
ꢀ1.1
ꢀ0.22
ꢀ2.8
ꢀ1.9
ꢀ2.5
5.65
4.92
4.74
5.52
3.21
3.51
3.66
5.77
5.63
5.95
5.85
5.48
4.70
5.81
4.47
4.73
4.52
4.88
4.74
4.31
4.72
l
[Mn(NO3)(dca)(tppz)]n (8)
a
b
c
Diamagnetic corrections calculated per one manganese center.
In the temperature range 1.8–300 K.
At the magnetic field 5 T and temperature 2 K.

B. Machura et al. / Polyhedron 53 (2013) 132–143
141
Table 4
Magnetic parametersa for complexes 1–7.
Compound
Exchange parameter J (cmꢀ1
)
Intermolecular interaction zJ0 (cmꢀ1
)
Tensor g
Agreement factor R
[Mn2(
[Mn2Cl2(
[MnCl(SCN)(tppz)(H2O)]ꢁH2O (3)
[Mn(NO3)2(tppz)(H2O)] (5)
[Mn(N3)(NO3)2(tppz)(H2O)] (6)
[Mn(SCN)2(tppz)] (7)
l
-Cl)2Cl2(tppz)2] (1)
0.15
0.32
ꢀ0.08
ꢀ0.16
ꢀ0.13
ꢀ0.03
ꢀ0.88
ꢀ0.22
1.95
1.91
1.99
1.99
1.94
1.98
6.11 ꢂ 10ꢀ5
6.00 ꢂ 10ꢀ4
6.68 ꢂ 10ꢀ4
2.03 ꢂ 10ꢀ4
2.75 ꢂ 10ꢀ3
1.37 ꢂ 10ꢀ3
l
1.1-N3)2(tppz)2] (2)
a
Calculated for the temperature range 1.8–300 K.
(3)), where J0 is the interaction between chains and z is the number
of nearest neighbor chains.
vM
vcMorr
¼
ð3Þ
2zJ0
1 ꢀ
ꢁ
vM
Nb2g2
The least-squares fit of the experimental data using this equa-
tion was limited to the whole temperature rangeꢀ1from 1.8 K up
to 300 K and leads to J = ꢀ0.1 cmꢀ1, zJ0 = ꢀ0.0 cm and g = 1.97
with the agreement factor R equal 6.9 ꢂ 10ꢀ5 for complex 8. Exper-
where N is the Avogadro’s number, g is the tensor, b is the Bohr
magneton, k is the Boltzmann constant, zJ0 is the intermolecular ex-
change parameter and z is the number of the nearest neighbors of
Mn(II) center.
The least-squares fit of the experimental data using these equa-
tions were limited to the temperature range from 1.8 K up to 300 K
(Table 4).
imental magnetic data plotted as
plex are shown in Fig. S7.
vMT versus T for 1D chain com-
Weak ferromagnetic behaviours of dinuclear compounds are
evident from the magnetic measurements. The MT value increases
v
only at the lowest temperature, reaching maximums at 3.3 K and
16 K and than decreases on cooling down to 1.8 K. for 1 and 2 com-
pound, adequate.
The magnetic data for dinuclear complexes were fitted using
the susceptibility equation for Mn(II) center with S = 5/2 and ex-
pressed by Eq. (5) [39].
The magnetic data of 1D chain complex indicated weak antifer-
romagnetic properties and have been fit using Fisher’s classical
Heisenberg results [38] for infinite linear chains.
The molecular field approximation has been used to account for
interaction between chains. Fisher’s Eq. (4) for magnetic suscepti-
bility of a classical spin chain is:
Ng2b2SðS þ 1Þ 1 þ u
Nb2g2
55 þ 30e5x þ 14e9x þ 5e12x þ e14x
v
¼
ð4Þ
v
¼
ð5Þ
kT 11 þ 9e5x þ 5e3x þ 7e9x þ 5e12x þ 3e14x þ e15x
3kT
1 ꢀ u
with
where x = ꢀ2J/kT and
J
is intradimer exchange interaction
ꢀ
ꢁ
ꢀ
ꢁ
parameter.
JSðS þ 1Þ
kT
JSðS þ 1Þ
u ¼ coth
ꢀ
To elucidate the significance of exchange between manga-
nese(II) ions in the crystal lattices, a molecular field correction
term [33] was also included, (Eq. (3)).
Experimental magnetic data plotted as
plex 1 are shown in Fig. S8.
kT
where J is the intrachain exchange parameter. If there are interac-
tion between chains, the actual observed susceptibility may then
the obtained using results of a molecular field calculation (Eq.
v
MT versus T for com-
Table 5
Oxidation of alcohols by the catalyst Oxone/n-Bu4NBr catalytic system.a
Entry
Substrate
Product
GC yield%
Compound 5
100
Compound 6
1
2
100
CH2OH
CH3
CH2OH
OMe
CH2OH
CHO
CH3
CHO
OMe
CHO
100
100
100
100
100
100
3
4
MeO
MeO
MeO
MeO
CH2OH
CH2OH
CHO
CHO
5
6
100
92
100
93
NO2
CH2OH
NO2
CHO
7
8
93
94
93
91
O2N
Cl
CH2OH
CH2OH
O2N
Cl
CHO
CHO
a
The molar ratios for catalyst:phase transfer agent:substrate:oxidant are 1:10:20:20, respectively. The reactions were run for 5 min at room temperature in a biphasic
medium (CH2Cl2/H2O).

142
B. Machura et al. / Polyhedron 53 (2013) 132–143
Table 6
Oxidation of sulfides catalyzed by 5 and 6.a
Entry
1
Substrate
GC yield %b
Selectivity to sulfoxide (%)c
100
Compound 5
Compound 6
45
46
2
3
53
59
49
100
100
57
4
5
44
33
47
39
100
100
CH3CH2-S-CH2CH3
a
The molar ratios for catalyst:imidazole:substrate:UHP are 1:10:20:40. The reactions were performed in (1:1) mixture of CH2Cl2/CH3OH (1 mL) under air at room
temperature.
b
The GC yield (%) are measured relative to the starting sulfide after 60 min.
Selectivity to sulfoxide = (sulfoxide%/(sulfoxide% + sulfone%)) ꢂ 100.
c
The least-squares fit of the experimental data for both ferro-
4. Conclusions
magnetic complexes are presented in Table 4.
For all equations, the criterion used in determination of the best
fit was based on minimization of the sum of squares of the
deviation:
Several novel halide and pseudohalides manganese(II) com-
plexes containing tppz ligand have been synthesized and fully
characterized. The studies have shown that the choice of manga-
nese(II) salt is crucial in the formation of manganese(II) complexes
with tppz and pseudohalide ligands. In the reported compounds
the manganese(II) ions show various coordination geometries but
tppz ligand coordinates to metal center in the most common tri-
dentate coordination mode. Manganese(II) ions of 1D chain net-
work [Mn(NO3)(dca)(tppz)]n are linked by a single end-to-end
sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
,
sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
n
n
1
1
2
R ¼
R
ð
vei xp
ꢀ
vci alc
Þ
R
2
vei xp
Þ
i¼1
i¼1
ð
vei xp
Þ
ð
dicyanamido group, whereas the metal center of dimers [Mn2(
l-
3.10. Catalytic experiments
Cl)2Cl2(tppz)2] and [Mn2Cl2( -N3- N1)2(tppz)2] are bridged by
l
j
chloride and azide ions, respectively. Future studies will be focused
on design of tppz-bridged manganese(II) complexes.
In order to compare catalytic reactivity of 5 and 6 with other
compounds, we used the same optimization condition with our
previous work [15a,b]. Reactions were performed at room temper-
ature under air in CH2Cl2/H2O containing the manganese complex,
tetra-n-butylammonium bromide, substrate and Oxone in
1:20:10:20 molar ratio, respectively. The system was applicable
for the oxidation of a wide variety of primary benzylic alcohols
to corresponding aldehydes (Table 5).
Benzylalcohols were oxidized to give the corresponding alde-
hydes with 91–100% conversion (entries 1–8). The substrates hav-
ing electron-donating and -withdrawing substituents in the
aromatic ring were compatible with this protocol. The change of
nature and site of substituents (methyl, methoxy, chloro and nitro)
in the aromatic ring of benzylalcohol to probe electronic effects
displayed no regular trends in the conversion. The catalytic oxida-
tion of alcohols in the given conditions showed excellent efficiency
in terms of yield and selectivity (100%).
Acknowledgements
This research was supported by the National Science Centre
(Poland) under grant No. 2011/01/B/ST5/01624. M.M.N. is grateful
to the Institute for Advanced Studies in Basic Sciences for financial
support.
Appendix A. Supplementary data
CCDC 896713, 896714, 896715, 896716, 896717, 896718,
896719and 896720 contain the supplementarycrystallographic data
for C48H32Cl4Mn2N12 (1), C48H32Cl2Mn2N18 (2), C25H20ClMnN7O2S (3),
C
C
26.47H18.94ClMnN9O (4), C24H18MnN8O7 (5), C24H18MnN10O4 (6),
26H16MnN8S2 (7) and C26H16MnN10O3 (8). These data can be
Also various types of structurally diverse substrates underwent
smooth and selective oxidation to produce the corresponding sulf-
oxides in good yields. In order to compare catalytic reactivity of 5
and 6 with other Mn(II) complexes, we used the same optimization
condition with our previous work [15c]. Aliphatic and aromatic
sulfides were effectively oxidized to the corresponding sulfoxides
with full selectivity and no over oxidation to sulfone were ob-
served (Table 6).
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223-
336-033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.poly.2013.01.015.
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