Synthesis, structure and optical features of single adamantanoid Hg-SePh-X anionic clusters stabilized by octahedral complexes (Ph = phenyl; X = Cl, Br, I)

Article abstract of DOI:10.1016/j.poly.2011.10.012

The ligand dppmo₂ [CH₂{P(O)Ph₂} ₂] (Ph = phenyl), MgCl₂·6H₂O, MgBr ₂, MgI₂, FeBr₂, CoBr₂, NiBr ₂ and Hg(SePh)₂ react one at

Full text of DOI:10.1016/j.poly.2011.10.012

Polyhedron 31 (2012) 596–600
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Polyhedron
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Synthesis, structure and optical features of single adamantanoid Hg–SePh–X
anionic clusters stabilized by octahedral complexes (Ph = phenyl; X = Cl, Br, I)
⇑
⇑
Rafael Stieler, Fabrício Bublitz, Ernesto Schulz Lang , Gelson Manzoni de Oliveira
Laboratório de Materiais Inorgânicos (LMI), Universidade Federal de Santa Maria (UFSM), Departamento de Química, Santa Maria, RS 97105-900, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 July 2011
Accepted 11 October 2011
Available online 17 October 2011
The ligand dppmo2 [CH2{P(O)Ph2}2] (Ph = phenyl), MgCl2Á6H2O, MgBr2, MgI2, FeBr2, CoBr2, NiBr2 and
Hg(SePh)2 react one at a time to give the complex salt of the general formula [M(dppmo2)3][Hg4X4
(SePh)6]Á4dmfÁH2O (M = Mg2+, Fe2+, Co2+, Ni2+; X = Cl, Br, I; dmf = dimethylformamide). The cations
[M(dppmo2)3]2+ are predominantly octahedral with axial angles from 175° to 178°. The adamantane like
anions [Hg4X4(SePh)6]2À are examples of single adamantanoid species, since these compounds normally
appear as polymers or fused cages. Adamantanoid cages are the preferential thermodynamic configura-
tion for this atomic aggregate. They appear as single molecules or ions however only in a halogen rich
reactions milieu.
Keywords:
Complex salts of IIA elements
Hg–Se-adamantane like cages
Thermodynamic stabilization as
adamantanoid cages
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
force supporting their formation seems to be the hardness of the
interaction Hg–X (X = Cl, Br, I) allied to the chelate effect of the
It is well known that the reaction of (RE)2 (R = aryl; E = Se, Te)
with transition metals M, mainly those of IIb subgroup, leads to
the formation of M(RE)2, and (under definite conditions), further
to polymeric, one-dimensional adamantane like cages, linked
dppmo2 ligand, which force the migration of the halides from
the hard metal to the adamantanoid system.
In earlier results obtained by our group concerning adamantane
cages, two of the four metallic centers attained only chalcogene
bridges, while the other two metals were also bounded respec-
tively to one halide ligand and to one pyridine or phosphine ligand.
The resulting products were polymeric cages linked by a chalco-
gene atom. In the present case, due to the increased concentration
of the halide ions, the anionic adamantanoid clusters were stabi-
lized as single monomers, with the coordination sphere of the
metal ions always completed by a halide ligand.
We report further the series of reactions of diphosphorylated
1,1-bis(diphenylphosphine)methane (dppm), with Hg(SePh)2 and
with MgCl2Á6H2O, MgBr2, MgI2, FeBr2, CoBr2, and NiBr2, as well as
the obtainment of the complexes of the general formula
[M(dppmo2)3][Hg4X4(SePh)6]Á4dmfÁH2O.
through a chalcogene atom. In the case of Hg2+ and Cd2+
,
adamantanoid structures seem to be the main stabilization form of
the resulting clusters products.
This kind of arrangement has been widely shown and discussed.
Some authors which have intensively contributed for the advance
of this synthetic and applicative chemistry (and some selected
works) are Dean [1], Eichhöfer [2,3], Fenske [4,5], Corrigan [6], Vit-
tal [7,8], Lang and Oliveira [9–12] and Ahlrichs [13]. Most of the
mentioned examples discussed by these authors consist of various
fused adamantane cages. Because of this frequent trend – fusion of
the cages À these adamantanoid species can be divided in three
general groups: polymeric cages [M4(EPh)7XL] (M = Cd2+, Hg2+
;
E = Se, Te; Ph = phenyl (or other aryl group); X = Cl, Br, I; L = PPh3,
pyridine) linked through a chalcogene atom; fused adamantane
cages (varying in number of cages and structural features), and iso-
lated single cages, not interacting with each other. This last type is
less common, since up to date few references of it have been made
in the literature.
2. Experimental
2.1. General
MgCl2Á6H2O, MgBr2, MgI2, FeBr2, CoBr2, NiBr2 and dppm (1,1-
bis(diphenylphosphine)methane) were obtained commercially
(Aldrich or Sigma) and used without further purification. Solvents
were purified and dried by standard procedures and freshly dis-
tilled before use. Hg(SePh)2 was prepared according to literature
procedure [14]. Elemental analyses (CHN) were carried out with
a Perkin-Elmer 2400 analyzer. Infrared spectra were measured on
In this sense, regarding the anionic clusters of the title com-
pounds of this work À all single adamantane cages À the driving
⇑
Corresponding authors. Tel.: +55 55 3220 8980; fax: +55 55 3220 8031
(G. Manzoni de Oliveira).
E-mail addresses: eslang@smail.ufsm.br (E. Schulz Lang), manzonideo@
smail.ufsm.br (G. Manzoni de Oliveira).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.10.012

R. Stieler et al. / Polyhedron 31 (2012) 596–600
597
2.4.1. Properties
[M(dppmo2)3][Hg4X4(SePh)6]·4dmf·H2O
Yellow crystalline substance. Melting point: 112–114 °C. Anal.
Calc. for C123H126Br4Hg4MgN4O11P6Se6 (3642.17): C, 40.56; H,
3.49; N, 1.54. Found: C, 40.27; H, 3.34; N, 1.37%. IR (KBr): 3050
−
−
−
X
Cl
Br
I
M
[ms(C–H)]; 2929 [mas(CH2)]; 2872 [ms(CH2)]; 1663 [m(C@O)]; 1574,
Mg2+
Fe2+
Co2+
Ni2+
1a
1b
2
1c
1475, 1437 [ms(C@C)]; 1176 [m(P@O)]; 1068, 1020 [dip(C@C–H)];
734, 690 [dop(C@C–H)], 461 cmÀ1 [dop(C@C–C)].
2.5. Preparation of [Mg(dppmo2)3][Hg4I4(SePh)6]Á4dmfÁH2O (1c)
3
According to the preparation of 1a, under addition of 0.028 g
(0.1 mmol) of MgI2 instead of MgCl2Á6H2O. After 5 days, yellow
crystals suitable for X-ray analysis were obtained. Yield: 0.134 g,
52% based on Hg(SePh)2.
4
Scheme 1. Identification of the title compounds according to the metal ions and
halide ligands present in the general formula above. Dppmo2 = CH2{P(O)Ph2}2;
Ph = phenyl; dmf = dimethylformamide.
2.5.1. Properties
Yellow crystalline substance. Melting point: 114–116 °C. Anal.
Calc. for C123H126Hg4I4MgN4O11P6Se6 (3830.13): C, 38.57; H, 3.32;
N, 1.46. Found: C, 38.65; H, 3.11; N, 1.31%. IR (KBr): 3053 [
ms(C–
a Bruker Tensor 27 mid-IR spectrometer. Melting points were
determined on a Microquimica MQAPF-301 melting point appara-
tus and are uncorrected. UV–Vis spectra in the range 200–800 nm
were obtained on a VARIAN Cary 100 spectrophotometer in the
solid state by diffuse reflectance with a LabsphereÒ integration
sphere.
H)]; 2931 [ as(CH2)]; 2874 [ s(CH2)]; 1667 [ (C@O)]; 1576, 1476,
m
m
m
1439 [ms(C@C)]; 1178 [m(P@O)]; 1070, 1022 [dip(C@C–H)]; 736,
692 [dop(C@C–H)], 464 cmÀ1 [dop(C@C–C)].
2.6. Preparation of [Fe(dppmo2)3][Hg4Br4(SePh)6]Á4dmfÁH2O (2)
The general formula of the title compounds, together with their
identification codes are shown in Scheme 1.
According to the preparation of 1a, under addition of 0.022 g
(0.1 mmol) of FeBr2 instead of MgCl2Á6H2O. After 3 days, red crys-
tals suitable for X-ray analysis were obtained. Yield: 0.055 g, 22%
based on Hg(SePh)2.
2.2. Preparation of dppmo2, [CH2{P(O)Ph2}2]
2.6.1. Properties
The phosphorylation of the white, crystalline powder dppm
Red crystalline substance. Melting point: 133–135 °C. Anal. Calc.
for C123H126Br4FeHg4N4O11P6Se6 (3673.71): C, 40.21; H, 3.46; N,
{1,1-bis(diphenylphosphine)methane},
a chelating ligand, was
carried out by oxidation of the diphosphine with oxygen in a
dichloromethane solution, in the presence of SnI4. The product
was isolated and purified using chromatographic methods. Yield:
63%.
1.53. Found: C, 39.30; H, 3.21; N, 1.28%. IR (KBr): 3050 [
2927 [ as(CH2)]; 2868 [ s(CH2)]; 1663 [ (C@O)]; 1574, 1475,
1437 [
ms(C–H)];
m
m
m
m
s(C@C)]; 1163 [m(P@O)]; 1069, 1020 [dip(C@C–H)]; 734,
690 [dop(C@C–H)], 462 cmÀ1 [dop(C@C–C)].
2.3. Preparation of [Mg(dppmo2)3][Hg4Cl4(SePh)6]Á4dmfÁH2O (1a)
2.7. Preparation of [Co(dppmo2)3][Hg4Br4(SePh)6]Á4dmfÁH2O (3)
To a solution of 0.102 g (0.2 mmol) of Hg(SePh)2 in 6 mL of dmf,
0.020 g (0.1 mmol) of MgCl2Á6H2O was added and the solution was
stirred for 10 min. Thereafter 0.083 g (0.2 mmol) of dppmo2 was
added, and the mixture was further stirred for 1 h. The solution
was then filtered in celite, and 6 mL of isopropanol was layered
in the mother solution. After 15 days yellow crystals suitable for
X-ray analysis were obtained. Yield: 0.100 g, 43% based on
Hg(SePh)2.
According to the preparation of 1a, under addition of 0.022 g
(0.1 mmol) of CoBr2 instead of MgCl2Á6H2O. After 5 days, pink crys-
tals suitable for X-ray analysis were obtained. Yield: 0.067 g, 27%
based on Hg(SePh)2.
2.7.1. Properties
Pink crystalline substance. Melting point: 117–119 °C. Anal.
Calc. for C123H126Br4CoHg4N4O11P6Se6 (3676.79): C, 40.18; H,
3.45; N, 1.52. Found: C, 39.85; H, 3.27; N, 1.35%. IR (KBr): 3052
[ms(C–H)]; 2929 [mas(CH2)]; 2870 [ms(CH2)]; 1665 [m(C@O)]; 1576,
2.3.1. Properties
1477, 1439 [ms(C@C)]; 1164 [m(P@O)]; 1070, 1022 [dip(C@C–H)];
Yellow crystalline substance. Melting point: 111–113 °C. Anal.
Calc. for C123H126Cl4Hg4MgN4O11P6Se6 (3464.33): C, 42.64; H,
3.67; N, 1.62. Found: C, 42.50; H, 3.49; N, 1.59%. IR (KBr): 3050
736, 692 [dop(C@C–H)], 463 cmÀ1 [dop(C@C–C)].
2.8. Preparation of [Ni(dppmo2)3][Hg4Br4(SePh)6]Á4dmfÁH2O (4)
[ms(C–H)]; 2929 [mas(CH2)]; 2872 [ms(CH2)]; 1662 [m(C@O)]; 1574,
1476, 1437 [ms(C@C)]; 1176 [m(P@O)]; 1069, 1020 [dip(C@C–H)];
According to the preparation of 1a, under addition of 0.022 g
(0.1 mmol) of NiBr2 instead of MgCl2Á6H2O. After 10 days, yellow
crystals suitable for X-ray analysis were obtained. Yield: 0.058 g,
24% based on Hg(SePh)2.
735, 691 [dop(C@C–H)], 461 cmÀ1 [dop(C@C–C)] (dip and dop = in-
plane and out-of-plane bendings, respectively).
2.4. Preparation of [Mg(dppmo2)3][Hg4Br4(SePh)6]Á4dmfÁH2O (1b)
2.8.1. Properties
According to the preparation of 1a, under addition of 0.018 g
(0.1 mmol) of MgBr2 instead of MgCl2Á6H2O. After 1 day, yellow
crystals suitable for X-ray analysis were obtained. Yield: 0.123 g,
51% based on Hg(SePh)2.
Yellow crystalline substance. Melting point: 113–115 °C. Anal.
Calc. for C123H126Br4Hg4N4NiO11P6Se6 (3676.57): C, 40.18; H,
3.45; N, 1.52. Found: C, 39.42; H, 3.30; N, 1.36%. IR (KBr): 3050
[ms(C–H)]; 2932 [mas(CH2)]; 2872 [ms(CH2)]; 1662 [m(C@O)]; 1574,

598
R. Stieler et al. / Polyhedron 31 (2012) 596–600
Table 1
Crystallographic data and refinement parameters for 1a, 1b and 1c.
1a
1b
1c
Empirical formula
Formula weight
T (K)
C
123H126Cl4Hg4MgN4O11P6Se6
C123H126Br4Hg4MgN4O11P6Se6
3642.17
296(2)
C123H126Hg4I4MgN4O11P6Se6
3830.13
296(2)
3464.33
296(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/c
15.2615(6)
27.5726(12)
29.3614(14)
90
monoclinic
P21/c
15.3905(2)
27.5345(5)
29.2996(5)
90
monoclinic
P21/c
15.5067(3)
27.7610(6)
29.6515(6)
90
a
(°)
b (°)
90.530(2)
90
12354.7(9)
4
1.862
6.952
90.7750(10)
90
12415.1(3)
4
1.949
8.120
90.7270(10)
90
12763.4(5)
4
1.993
7.613
c
(°)
V (Å3)
Z
qcalc (g cmÀ3
)
l
(MoK
a
) (mmÀ1
)
k (Å)
F(000)
0.71073
6696
0.71073
6984
0.71073
7272
h Range (°)
Completeness to hmax (%)
1.48–28.96
97.9
1.57–28.75
99.8
1.50–27.52
99.9
Collected reflections
Unique reflections [Rint
119871
32032 [0.0606]
GAUSSIAN
123820
32157 [0.0605]
GAUSSIAN
123466
29336 [0.0581]
GAUSSIAN
]
Absorption correction
Goodness-of-fit (GOF) (F2)
0.883
0.922
0.983
Final R indices [I > 2
R1 (all data)
r(I)]
R1 = 0.0487, wR2 = 0.1105
0.1234
R1 = 0.0500, wR2 = 0.1149
0.1200
R1 = 0.0517, wR2 = 0.1318
0.1014
wR2 (all data)
0.1283
0.1323
0.1478
Table 2
Crystallographic data and refinement parameters for 2, 3 and 4.
2
3
4
Empirical formula
Formula weight
T (K)
C
123H126Br4FeHg4N4O11P6Se6
C123H126Br4CoHg4N4O11P6Se6
3676.79
296(2)
C123H126Br4Hg4N4NiO11P6Se6
3676.57
296(2)
3673.71
296(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/c
15.4150(4)
27.5189(7)
29.3358(7)
90
monoclinic
P21/c
15.4050(3)
27.5380(6)
29.2475(6)
90
monoclinic
P21/c
15.3378(3)
27.6052(5)
29.2739(6)
90
a
(°)
b (°)
90.9150(10)
90
12442.8(5)
4
1.961
8.208
90.7060(10)
90
12406.5(4)
4
1.968
8.249
90.8870(10)
90
12393.2(4)
4
1.970
8.276
c
(°)
V (Å3)
Z
qcalc (g cmÀ3
)
l
(MoK
a
) (mmÀ1
)
k (Å)
F(000)
0.71073
7040
0.71073
7044
0.71073
7048
h Range (°)
Completeness to hmax (%)
1.51–28.73
99.9
1.48–28.77
99.6
1.48–28.74
99.8
Collected reflections
Unique reflections [Rint
123860
32205 [0.0564]
GAUSSIAN
127317
32148 [0.0731]
GAUSSIAN
127688
32108 [0.0824]
GAUSSIAN
]
Absorption correction
Goodness-of-fit (GOF) (F2)
0.929
0.924
0.876
Final R indices [I > 2
R1 (all data)
r(I)]
R1 = 0.0488, wR2 = 0.1138
0.1114
R1 = 0.0549, wR2 = 0.1302
0.1283
R1 = 0.0530, wR2 = 0.1195
0.1373
wR2 (all data)
0.1299
0.1504
0.1418
1475, 1437 [
m
s(C@C)]; 1163 [
m
(P@O)]; 1068, 1020 [dip(C@C–H)];
parameters for all non-hydrogen atoms. Hydrogen atoms were in-
cluded in the refinement in calculated positions.
734, 690 [dop(C@C–H)], 461 cmÀ1 [dop(C@C–C)].
In the Gaussian absorption corrections the program XPREP was
2.9. X-ray structural determination
used as part of SADABS
.
Additional electron density was localized in voids (1301 Å3
summing to 450 eÀ for 1a; 1239 Å3 summing to 419 eÀ for 1b;
1298 Å3 summing to 478 eÀ for 1c; 1226 Å3 summing to 398 eÀ
for 2; 1238 Å3 summing to 387 eÀ for 3; 1214 Å3 summing to
456 eÀ for 4; total potential solvent accessible volume) corre-
sponding to approximately 12 molecules of dimethylformamide
and 4 molecules of water, per unit cell. This residual electron den-
sity was removed using the SQUEEZE routine in PLATON and are
Data were collected with a Bruker APEX II CCD area-detector
diffractometer and graphite-monochromatized MoK
a radiation.
The structures were solved by direct methods using SHELXS-97
[15]. Subsequent Fourier-difference map analyses yielded the posi-
tions of the non-hydrogen atoms. Refinements were carried out
with the SHELXL-97 package [15]. All refinements were made by
full-matrix least-squares on F2 with anisotropic displacement

R. Stieler et al. / Polyhedron 31 (2012) 596–600
599
Table 3
Average lengths (Å) of the six metal–O bonds of the octahedral cations and of the 12
Hg–Se and the 4 Hg–X bonds of the adamantane like anions of 1a, 1b, 1c, 2, 3 and 4.
1a
1b
1c
2
3
4
M–O
Hg–Se
Hg–X
2.091
2.632
2.567
2.088
2.633
2.661
2.081
2.646
2.799
2.134
2.633
2.664
2.104
2.635
2.657
2.072
2.632
2.662
Fig. 1. Structure of the cations [M(dppmo2)3]2+ {M = Mg2+ (1a, 1b, 1c), Fe2+ (2), Co2+
(3), Ni2+ (4); dppmo2 = CH2{P(O)Ph2}2}. For clarity, the hydrogen atoms and the
solvate molecules (dmf and water) are not shown.
Fig. 3. The absorption spectra of polycrystalline samples of 1a, 1b, and 1c.
Fig. 2. Adamantane like structure of the anions [Hg4X4(SePh)6]2À. {X = Cl (1a), Br
(1b, 2, 3, 4), I (1c)}. For clarity, the hydrogen atoms and the solvate molecules (dmf
and water) are not shown.
Fig. 4. The absorption spectra of polycrystalline samples of 2, 3, and 4.
included in the molecular formula [15,16]. Crystal data and more
details of the data collections and refinements are contained in Ta-
bles 1 and 2.
adamantane like, respectively. In earlier works the environment
used to be somewhat thin, regarding the halogen reactants. On
the contrary, in the present work we have used a larger concentra-
tion of halogens, so that the adamantanoid groups always present
four halide ligands in the coordination sphere of the same number
of Hg atoms. It has been experimentally shown that for this type of
complex the adamantanoid geometry is the preferential thermody-
namic assembly. The complexes 2, 3 and 4 were prepared as a com-
plement for the IIA group complexes 1a, 1b and 1c, but also to
prove if the transition metal ions Fe2+, Co2+ and Ni2+ – intermediary
acids with the configurations d6, d7 and d8 respectively – would
reproduce the reactivity of the IIA ion Mg2+ (a hard acid) with re-
gards to the hard base dppmo2. Not only the same octahedral
structures were reproduced, but also the axial octahedral angles
are in the same order for all complexes, varying from 175° to
3. Discussion
3.1. X-ray structures
The structures of the compounds 1a, 1b, 1c, 2, 3 and 4 are
represented in Figs. 1 and 2. The cation and anion are displayed
separately for clarity, and also for this reason the hydrogen atoms
and the solvate molecules (dmf and water) are not shown. Table 3
shows the medium distance of the six metal–O bonds of the
octahedral cationic species of 1a, 1b, 1c, 2, 3 and 4, together with
the average distance of the 12 Hg–Se and 4 Hg–X bonds of the
adamantanoid anions of the title complexes. All the cationic and
anionic species present the same structure, octahedral and

600
R. Stieler et al. / Polyhedron 31 (2012) 596–600
178°. The three dppmo2 molecules embrace the metal atoms in a
slightly distorted octahedral configuration, only one dppmo2 li-
gand (O3 and O4) occupying simultaneously two equatorial
positions.
Appendix A. Supplementary data
CCDC 825259, 825260, 825261, 825262, 825263 and 825264
contain the supplementary crystallographic data for 1a, 1b, 1c,
2, 3 and 4. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
3.2. Optical properties
Figs. 3 and 4 display the UV–Vis absorption spectra of 1a, 1b, 1c,
2, 3 and 4, in the solid state at room temperature. The estimated
band gaps are ca. 2.76 eV (449 nm) for 1a, 2.72 eV (456 nm) for
1b, 2.75 eV (451 nm) for 1c, 2.71 eV (457 nm) for 2, 2.71 nm
(457 nm) for 3 and 2.75 eV (451 nm) for 4, respectively. The
absorption wavelength for the energy gaps were calculated by
laying the tangent line through the inflection point of the first in-
crease of the curves. The intersection point of the tangent with
the abscissa was considered as wavelength of the gap [4]. A
detailed assignment of the bands is complicated as there are sev-
eral possible absorption processes for the compounds. However,
the broad bands at higher wavelengths (Fig. 4) can be attributed
to the spin-allowed d–d transitions in octahedral coordinated
Fe2+, Co2+ and Ni2+ ions. On the other hand, the intense bands at
lower wavelengths probably originate from ligand-to-metal charge
transfer (LMTC) transitions, chiefly Se(4p) ? Hg(6s), overlapped by
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p–
p⁄ transitions of the dppmo2 and SePhÀ ligands. These assertions
are supported by earlier works [17,18], and the LMTC transitions
do not exclude the realization of metal-to-ligand charge transfer
transitions (MLCT) between M2+-dominated (M2+ = Mg2+, Fe2+
Co2+, Ni2+) to dppmo2-dominated orbitals.
,
Acknowledgment
This work was supported with funds from CNPq, CAPES and FA-
PERGS (Brazilian agencies).