Spectroscopic and thermal studies of Mn(II), Co(II) and Ni(II) bromide m-methylaniline complexes

Article abstract of DOI:10.1016/S0022-2860(03)00448-4

The complexes of the MBr₂L₂ [M: Mn(II), Co(II) and Ni(II); L: m-methylaniline (mMA)] form have been prepared and characterized by their elemental analyses, thermogravimetric analyses, magnetic moment measurements, UV-vis, IR and Raman spectral studies. Elemental analysis suggests the stoichiometry to be 1:2 (metal:ligand). Thermal decomposition studies, using thermogravimetry show that the intermediate metal complexes are formed for complexes during their decomposition processes, the metal oxide being finally produced in each case. IR and Raman bands of the complexes have been assigned as compared with the free ligand. Coordination effects on the internal modes of mMA have been discussed. A polymeric octahedral geometry around metal ion with bridging bromides has been proposed for the Mn(II) and Ni(II) complexes, while tetrahedral geometry around Co(II) ion with C _2v symmetry is suggested for the Co(II) complex.

Full text of DOI:10.1016/S0022-2860(03)00448-4

Journal of Molecular Structure 657 (2003) 385–393
www.elsevier.com/locate/molstruc
Spectroscopic and thermal studies of Mn(II), Co(II) and Ni(II)
bromide m-methylaniline complexes
*
K. Golcuk , A. Altun, M. Kumru
Department of Physics, Fatih University, B.CEKMECE, Istanbul 34900, Turkey
Received 20 May 2003; revised 2 July 2003; accepted 3 July 2003
Abstract
The complexes of the MBr2L2 [M: Mn(II), Co(II) and Ni(II); L: m-methylaniline (mMA)] form have been prepared and
characterized by their elemental analyses, thermogravimetric analyses, magnetic moment measurements, UV–vis, IR and
Raman spectral studies. Elemental analysis suggests the stoichiometry to be 1:2 (metal:ligand). Thermal decomposition studies,
using thermogravimetry show that the intermediate metal complexes are formed for complexes during their decomposition
processes, the metal oxide being finally produced in each case. IR and Raman bands of the complexes have been assigned as
compared with the free ligand. Coordination effects on the internal modes of mMA have been discussed. A polymeric
octahedral geometry around metal ion with bridging bromides has been proposed for the Mn(II) and Ni(II) complexes, while
tetrahedral geometry around Co(II) ion with C2v symmetry is suggested for the Co(II) complex.
q 2003 Elsevier B.V. All rights reserved.
Keywords: MnBr2, CoBr2 and NiBr2 complexes; m-methylaniline; Spectroscopy; Thermal analysis; Structure
1. Introduction
thermogravimetric (TG) behaviors, magnetic
moments, electronic spectra and vibrational spectra
of the metal(II) [Mn(II), Co(II) or Ni(II)] bromide
with m-methylaniline complexes in the present study.
A detailed vibrational bands analysis of each metal
complex is also given. The spectroscopic investi-
gations are used to obtain further information about
the local structure around the metal ions.
Aniline and its derivatives are of great industrial
importance. These compounds are widely used for
producing polyurethanes, rubbers, pesticides and dyes
and also found in the environment [1]. Recently, their
toxicity effects to Daphnia magna were also studied
[2]. Hence, understanding of their molecular proper-
ties and the reactions they experience is very
important. Besides, their metal(II)halide complexes
have been interested for decades [3–12]. As a
continuation of previous works [10–12], we report
2. Experimental
All the chemicals used were reagent grade (Fluka–
Aldrich). The polycrystalline complexes were pre-
pared using the method given in Refs. [10,11].
*
Corresponding author. Tel.: þ90-212-8890810; fax: þ90-212-
8891142.
E-mail address: kgolcuk@fatih.edu.tr (K. Golcuk).
0022-2860/03/$ - see front matter q 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-2860(03)00448-4

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K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
Composition and purity (C, H, N, and M) were
determined by microanalysis (see Table 1).
spectra of the complexes have been considered.
The only coordination site for the ligand m-
methylaniline (mMA) is the nitrogen atom of the
amine group. Hence, we pay attention to –NH2
group vibrations upon complexation. The FT-IR
spectra of mMA and its complexes are shown
together in Fig. 1. The Raman spectrum of cobalt
complex exhibits very strong florescence, covering
all the vibrational bands. Hence, we could not
obtain a clear Raman spectrum of Co(II) complex
for several attempts. We only give FT-Raman
spectra of the Mn(II) and Ni(II) complexes and free
ligand in Fig. 2.
Electronic spectra in EtOH were recorded on a
Perkin Elmer Lambda 9 UV–VIS–NIR spectrometer
in the range 190–1100 nm.
Measurements of magnetic moments at room
temperature were made using the Evans method
with a Sherwood Sci. magnetic balance. The molar
susceptibilities were corrected for the diamagnetism
of the constituent atoms using Pascal’s constants.
Thermal analyses were made on a Mettler Toledo
TG50 thermobalance under a N2 flow (flow rate,
30 cm3 min21). The samples were heated in an Al2O3
crucible at rate of 10 8C min21
.
All observed vibrational bands and their assign-
ments are given in Table 2. Vibrational mode
assignments of the free mMA are based on ab initio
and DFT calculations and fully reported in Ref. [13].
A band for band correspondence is also considered for
the spectra of the compounds.
The FT-IR spectra were recorded using KBr discs
over range 4000–400 cm 21 on a Perkin Elmer
Paragon 1000 FT-IR. The 500–200 cm 21 region
spectra were recorded using polyethylene discs over
the range 500–200 cm 21 on a Mattson 2030 Galaxy
FT-IR spectrometer.
The n NH asymmetric and symmetric stretching
bands are shifted towards lower wavenumbers on the
formationofthecomplexes.Thiswouldsuggestthatthe
N atom of the amine group coordinates to metal ion
[3–12]. The shifting to the lower frequencies can be
explained as a weakening of the N–H bonds resulting
fromtheelectrondrainagefromthenitrogenatomdueto
its coordination to the metal atom [10–12].
Raman spectra were recorded on a Bruker RFS
100/S FT-Raman Spectrometer in the range 3600–
70 cm21. A 1.5 W Nd–YaG air-cooled laser deliver-
ing excitation wavelength of 1064 nm was used.
3. Results and discussion
The NH2 scissoring frequency at 1622 cm21 in
the mMA spectrum is lowered 50 cm21 by
coordination. The change in hybridization of
nitrogen orbitals and therefore the alteration of
HNH angle decreases NH2 scissoring force constant
and causes the shifts upon the complexations. We
have assigned the band observed at 1293 cm21 to
the n CN stretching for free mMA. Vibrations of
this mode occur at lower frequencies in the
complexes, in line with the decrease in the CyN
double bond character [11].
Elemental analysis data, listed in Table 1, suggest
that the complexes have 1:2 (M:L) stoichiometry.
Based on the elementary chemical analysis has been
suggested, for all the compounds, [MBr2(mMA)2]
form.
3.1. Vibrational spectroscopy
In order to get data conceiving the ligand way
of coordination to the metal ions, the vibrational
Table 1
Analyses (%) of the metal complexes
Compound
Colour
Found (Calc.)%
M
C
N
H
[MnBr2(mMA)2]n
[CoBr2(mMA)2]
Pale pink
Blue
12.88(12.80)
13.49(13.61)
38.90(39.19)
38.69(38.83)
6.49(6.53)
6.45(6.47)
4.18(4.23)
4.26(4.19)
[NiBr2(mMA)2]n
Light yellow
13.23(13.56)
39.29(38.85)
6.89(6.47)
4.15(4.19)

K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
387
Fig. 1. FT-IR spectra of (a) mMA, (b) [MnBr2(mMA)2]n, (c) [CoBr2(mMA)2] and (d) [NiBr2(mMA)2]n.
The metal-sensitivity of the n NH and n CN bands
is in the sequence Co , Ni , Mn which is the inverse
order of the masses of the metal atoms.
and suggested that the NH2 wagging vibration was
observed as a very strong and coordination
sensitive band in the region 1185–1000 cm21
,
Jungbauer and Curran [14] reported a study of
some deuterated aniline metal halide complexes
while it appeared at 670 cm21 in the IR spectrum
of aniline. The similar shifts were also observed in
Fig. 2. FT-Raman spectra of (a) mMA, (b) [MnBr2(mMA)2]n and (c) [NiBr2(mMA)2]n.

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K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
Table 2
Infrared and Raman frequencies of mMA and metal complexes
mMA
IR
[MnBr2(mMA)2]n
IR Ra
[CoBr2(mMA)2]
IR
[NiBr2(mMA)2]n
IR Ra
Assignment
Ra
3435 s
3354 s
3328 m
3296 m
3124 w,br
3028 w,sh
3012 w,sh
3330 w
3297 w
3264 s
3215 s
3116 m
3317 s
3236 s
3121 m
3034 w
3316 w
3235 s
3122 w
3053 s
n NH (asym.)
n NH (sym.)
2 £ 1620 over
n CH ring
n CH ring
n CH ring
n CH ring
n CH3 (asym.)
n CH3 (sym.)
NH2 (sciss.)
n CC ring
n CC ring
n CC ring
n CC ring
b CH3 (asym.)
b CH3 (asym.)
b CH3 (sym.)
b CH
n CN
n CN
3353 m,br
3212 m,br
3046 s
3012 s
2974 m
3218 m
3034 m
3015 m,sh
2975 m,sh
2946 m,sh
2919 m
2857 w
3046 s
3014 m,sh
2976 w
2951 w,sh
2917 s
2860 w
3033 m
2966 vw
2977 w
2947 w
2917 s
2919 s
2857 m,sh
1620 s
2914 w
2858 w
1572 s
1616 s
1598 s
2918 m
2855 vw
1572 vs
1615 s
2919 w
2855 vw
1573 s
2852 w,sh
1622 vs
1614 s
1598 s
1617 s
1614 m,sh
1597 s
1591 vs
1513 m,sh
1493 vs
1469 s
1443 m,sh
1381 w
1314 m
1293 s
1590 m
1514 vw
1493 vw
1596 s
1594 m,sh
1516 vw
1496 vs
1467 s
1437 m,sh
1374 w
1309 vw
1282 vw
1262 m
1170 m
1143 w
1087 m
999 m
919 m
886 w
862 w
773 vs
733 m
690 s
1043 vs
575 w
549 w
1516 vw,sh
1494 vs
1466 s
1517 vw
1492 vs
1470 s
1436 m,sh
1374 w
1494 w
1463 vw
1440 w,br
1378 s
1312 w
1278 m,sh,
1268 s
1170 m
1146 vw
1085 vw
1000 vs
919 w
1472 m
1440 w,br
1382 m
1313 vw
1284 w,sh
1261 s
1168 m
1139 vw
1087 m
1000 vs
920 m
1447 w,br
1378 m
1313 m,sh
1293 s
1374 w
1313 vw
1264 m
1277 w
1257 s
1167 w
1144 w
1094 vs
996 m,sh
916 m
889 m
867 m
780 vs
729 m
688 vs
1035 w
568 m
546 w
1170 s
1166 m
1170 m
b CH ring
n CCH3
1077 w
996 m
926 w
870 m
855 m
775 vs
726 m,sh
691 vs
655a
1075 w
996 m
928 w
1086 m
990 vs
918 vs
882 s
854 m
776 vs
730 m
690 vs
1022 vs
557 s
b NH2 (rock.)
b CCC ring
b CCC ring
g CH ring; g CCC
g CH ring; g CCC
g CH ring; g CCC
Breathing
g CCC ring
g NH2 (wagg.)
g CCC ring
b CCC ring
b CCC ring
g CCC ring
n (M–N)
886 w
866 w
778 w
728 s
899 w
784 w
738 s
733 s
690 m
1058 s
575 vw
549 m
518 s
1025 m
557 m
538 m
543 m
518 m
431 w
543 m
518 vw,sh
441 s
545 s
520 s
441 vw
419 w
331 m
518 vw
445 m
420 m
399 m
445 m
415 s
372 m, br
354 m,br
297 s
450 w
417 vw
412 s
329 m
n (M–N)
357 m,br
297 m
294 m
234 m
296 m
285 m
570 s
293 m
284 m
574 m
292 s
b CNH2; b CH3
g NH2 (twist.)
652 m
635 m
246 s
618 s
608 m
257 m
240 m
221 m
253 w
235 w,sh
215 s
NMN deformation
218 m
221 s
219 m
234 s
210 s
220 s
g CNH2g CCC ring
n (M–Br)t
n (M–Br)t
192 m
167 m
194 s
152 m
n (M–Br)b
n (M–Br)b
Key: n; stretching; b; in plane deformation; g; out-of-plane deformation s, strong; vs, very strong; m, medium; w, weak; vw, very weak; sh,
shoulder; br, broad.
a
Mode has not been observed, but has been found based on ab initio and DFT calculations [13].
our previous works for some metal bromide and
iodide mMA complexes [10–12]. We therefore
assign the IR bands at 1022, 1035 and 1043 cm21
to the NH2 wagging mode for the Mn(II), Co(II)
and Ni(II) complexes, respectively. The explicit
metal-sensitivity can be explained directly by
mechanical coupling of this mode with M–N
vibrations [15].
The weak band at 1077 cm21 is attributed to NH2
rocking mode of free mMA, while it is shifted towards
the upper frequencies by complex formation. A study
of normal coordinate analysis on aniline revealed that

K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
389
the band at 216 cm21 (NH2 twisting mode) was found
at 605 cm21 in aniline–Cd complex [9]. Hence, we
have assigned the 652–570 cm21 region bands of the
complexes to the NH2 twisting vibrations.
A very intense band is found near 1000 cm21 in
both Raman spectra of mMA and its complexes,
indicating the meta-disubstituted ring. This band is
due to a symmetrical in plane ring deformation [13].
The upward shifts of the NH2 rocking and wagging
vibrations follow the sequence Ni . Mn. This order
obeys the Irving–Williams stability sequence and can
be correlated with the increase in the second
ionization potential of the metals.
210 cm21 [4–6]. In [CoBr2(mMA)2], the metal ion is
involved in a tetrahedral N2CoBr2 skeleton. Assuming
C2v symmetry for this complex, both the anti-
symmetric and symmetric CoBr2 and CoN2 stretching
vibrations are IR active [16]. The n (Co–Br)t and n
(Co–N) stretching vibrations can be described with
A1 þ B1 and A1 þ B2 representations, respectively.
Thus, the low frequency spectrum is consistent with
previously reported tetrahedral Co(II) complexes
[3–6,14,16].
The stretching vibrations of the bridging M–Br–M
bonds, i.e. n (M–Br)b, should appear below 200 cm21
[17]. In Raman spectrum of Mn(II) complex (see Fig.
2(b)), the 192 and 167 cm21 bands are assigned to n
(Mn–Br)b. Similarly, the 194 and 152 cm21 bands in
Raman spectrum of Ni(II) complex (see Fig. 3(c)) are
due to the stretching bands of bridging Ni–Br–Ni
bonds, i.e. n (Ni–Br)b. Hence, the appearance of the n
(M–Br)b vibrations indicates a polymeric octahedral
structure around metal ions with exclusively bridging
bromides for [MnBr2(mMA)2]n and [NiBr2(mMA)2]n
complexes, where n shows the polymeric character of
the complexes. As a result, the local environments for
both Mn and Ni ions consist of polymeric chains in
which each metal atom is surrounded by four bromine
atoms and two nitrogen atoms of the ligands, as also
The metal–ligand bands are helpful for determin-
ing the local structure around metal ions. It is
considered that the metal–ligand vibrations occur
below 500 cm21 [3–12]. Assignments of the n (M–
N) and n (M–Br) vibrations, listed in Table 2, have
been given carefully by considering the internal
modes of mMA and comparing with literature reports
[3–16]. The 500–200 cm21 region spectra of the
complexes are shown in Fig. 3.
For the Co (II) complex, the medium IR bands at
420 and 399 cm21 have been ascribed as n (Co–N)
stretching vibrations. The terminal Co–Br bond
stretching, i.e. n (Co–Br)t bands occur at 230 and
Fig. 3. The 500–200 cm21 region spectra of (a) [NiBr2(mMA)2]n, (b) [MnBr2(mMA)2]n and (c) [CoBr2(mMA)2].

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K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
Fig. 4. The proposed molecular structure of (a) [CoBr2(mMA)2] and (b) [MnBr2(mMA)2]n and [NiBr2(mMA)2]n complexes (M: Mn, Ni; N:
nitrogen atom of the mMA).
reported in aniline complexes [3,5,8,16]. The pro-
posed molecular structures of the complexes are
shown in Fig. 4.
3.2. UV–vis spectroscopy and magnetochemistry
The electronic spectral data and magnetic moment
values of the complexes are given in Table 3. The
UV–vis spectrum of Mn(II) complex shows bands
around 18315 and 24271 cm21. Both of the d–d
transitions are spin forbidden and therefore of low
intensity. The complex is pale pink in color. The
bands at 24271 and 18315 cm21 correspond to
The coordination number effect on metal–ligand
vibration frequencies is known to be a substantial one
[4]. The decreased coordination number which
accompanies substitution of Co(II) by Mn(II) is
expected to lead to a increase in n (M–N) as is
observed. Substitution of Ni(II) by Co(II) is expected
to cause an decrease in n (M–N). This result arises
from the bonding capacity of the metal ion being
distributed over more bands with consequently lower
metal–ligand force constants [4]. If the coordination
number remains unchanged, n (M–N) bands follow
the sequence Mn , Ni. The difference between the
frequencies of corresponding n (M–N) bands in each
Mn–Ni pair might be attributed to the fact that the
Ni(II) complex is stabilized by crystal field splitting
whereas the Mn(II) complex is not.
4
6
4
6A1g(S) ! A1g(G), 4Eg(G) and A1g(S) ! T1g(G)
transitions, respectively. The spectrum bands are
consistent with those predicted six coordinated
polymeric octahedral Mn complexes [5]. This geo-
metry is confirmed by the value of magnetic moment
(meff ¼ 5.80 BM) as well, which is a characteristic of
high spin octahedral Mn(II) complex [19]. The
magnetic moment value of the complex is slightly
lower than spin-only value of a Mn(II) ion, showing
Mn–Mn interaction.
The very strong Raman bands below 100 cm21 are
ascribed as the lattice mode of the solid complexes
[18] and couple with torsional mode of CH3.
In the UV–vis spectrum of Ni(II) complex, two
bands have been observed at 12820 and
23809 cm21. The spin allowed electronic transitions

K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
391
Table 3
UV–vis spectral data, colors and magnetic moments of the metal complexes
Compound
Color
Band position (cm21
)
Transition
meff (BM)
4
[MnBr2(mMA)2]n
Pale pink
18315
24271
14925
6A1g(S) ! T1g(G)
5.80
4.73
4
6A1g(S) ! A1g(G),4Eg(G)
4A2(F) ! T1(P)
4
2
[CoBr2(mMA)2]
[NiBr2(mMA)2]n
Blue
15625
16077
16649
4A2(F) ! E(G)
4A2(F) ! T1(G)
2
4A2(F) ! T2(G)
2
3
Light yellow
12820
23809
3A2g(F) ! T1g(P)
3.20
3
3A2g(F) ! T1g(F)
for d8 octahedral Ni(II) ion are expected from
The electronic absorption spectrum of Co(II)
complex shows one broad band in visible region at
14925 cm21 and gives some shoulders around 15625,
16077 and 16649 cm21. The complex is blue in color,
which is a characteristic for tetrahedrally coordinated
cobalt complexes [21,22]. The band at 14925 cm21 is
a spin allowed electronic transition and arises from
3A2(F) ground state to T2g(F), T1g(P) and T1g(F)
states. But we have found only two of the possible
electronic transitions. The absorption band with
3
3
3
lower energy (12820 cm21
)
arises from
3
3A2g(F) ! T1g(F) transition, while the absorption
band with higher energy (23809 cm21) corresponds
3
3
4
to A2g(F) ! T1g(P) transition. The positions of
the d–d transitions indicate that the Ni ion is in a
polymeric octahedral environment with bridging
bromides [5]. The magnetic moment value
(meff ¼ 3.20 BM) of the complex, which shows
the presence of two unpaired electrons, lies in the
region expected for octahedral Ni complexes [3].
This value is only a little higher than the calculated
value for two unpaired electron, which indicates
metal–metal interaction is absent, and the discre-
pancy can be attributed to the contribution made by
orbital motion of the electrons [20].
4A2(F) ! T1(P). The bands at 15625, 16077 and
16649 cm21 come from spin forbidden transitions and
4
2
4
2
assignable to A2(F) ! E(G), A2(F) ! T1(G) and
4A2(F) ! T2(G), respectively, indicating fine struc-
2
tures due to pseudo-tetrahedral structure. Holm and
Cotton [22] have made an extensive study on
magnetic investigation of a number of cobalt com-
plexes. They have reported that cobalt-halide with p-
methylaniline (pMA) complexes have a tetrahedral
arrangement around cobalt ion and possess magnetic
moment values laying in the range 4.80–4.72 BM.
We have also found the value of magnetic moment of
Table 4
Thermal decomposition processes of the metal complexes
Compound
Process
Temp. range (8C)
DTG peak temp. (8C)
Weight loss (%)
Calc.
Found
[MnBr2(mMA)2]n
[MnBr2(mMA)2] ! [MnBr2(mMA)0.4
[MnBr2(mMA)0.4] ! MnBr2
MnBr2 ! MnO
]
115–183
183–310
350–750
178
202
670
29.12
19.83
33.39
26.68
17.78
35.93
[CoBr2(mMA)2]
[NiBr2(mMA)2]n
[CoBr2(mMA)2] ! CoBr2
97–350
250
690
49.40
33.29
47.70
36.62
CoBr2 ! CoO
390–710
[NiBr2(mMA)2] ! NiBr2
NiBr2 ! NiO
90–380
235
685
50.33
33.08
49.31
34.88
400–720

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K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
Fig. 5. TG-DTG curves of [MnBr2(mMA)2]n (sample mass: 8.9907 mg, heating ratio: 10 8C/min, under N2 atmosphere with a flow rate:
5 ml/min).
[CoBr2(mMA)2] complex as 4.73 BM which falls into
that reported region. Hence, the value obtained for
magnetic moment proposes that complex has a high
spin tetrahedral N2CoBr2 coordination sphere.
range) for the Co(II) complex corresponds to the loss
of 2 mol of mMA. The second decomposition stage
registered between 390–710 8C matches the
decomposition of CoBr2 finally to CoO. The Ni(II)
complex loses its 49.31% mass in the range 90–
380 8C, corresponding to the complete removal of
mMA from the complex. The second step in the range
400–720 8C in which the maximum mass loss occurs
at 685 8C is the evidence of decomposition of NiBr2 to
metal oxide. The observed weight losses for the
decomposition processes in each of the compounds
compare favorably with the theoretical values listed in
Table 4. The initial decomposition temperature of
each complex reveals the following thermal stability
sequence Mn . Co . Ni which is the inverse order
of Irwing–Williams series [20].
3.3. Thermal analysis
Thermal decomposition data of the metal com-
plexes are listed in Table 4. As an example, TG and
DTG traces for Mn(II) complex are shown in Fig. 5. In
the TG-DTG curves of Mn(II) complex no weight
changes are observed until 115 8C, where an initial
weight loss is observed, due to the loss of 60% mMA
molecules. In the temperatures between 183 and
310 8C, the rest of the mMA molecules is removed
immediately from the complex, leaving the inter-
mediate MnBr2. The metal salt starts to decompose at
350 8C. The residual weight is in good agreement with
the value required for MnO.
4. Conclusion
The Co(II) and Ni(II) complexes decompose in a
two-step mass loss reaction. The first step (97–350 8C
The spectroscopic studies of mMA complexes of
some metal bromides show that coordination occurs

K. Golcuk et al. / Journal of Molecular Structure 657 (2003) 385–393
393
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via nitrogen atom of the mMA. The IR and Raman
spectra reveal the type of the coordination around
each metal ion. The information referring to the
geometry of the studied complexes is also obtained
from the electronic spectra and from values of
magnetic moments. Without X-ray analysis, no define
structure can be described. However, the spectro-
scopic and magnetic data suggest that the Co(II)
complex has a tetrahedral structure, with the cobalt
ion bonded to two bromide ions and two nitrogen
atoms from two different molecules of ligand, while
the Mn(II) and Ni(II) complexes have the metal ions
in a polymeric octahedral environment with bridging
bromides. The metal complexes decompose via
intermediate complexes to give the metal oxides.
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