Synthesis, structural characterization and growth features of some (Ph)Se-Cd cluster compounds (Ph = phenyl)

Article abstract of DOI:10.1016/j.poly.2010.02.023

Cd(SePh)₂, CdBr₂·4H₂O/CdI₂ and PCh₃ (Ph = phenyl; PCh₃ = tricyclohexylphosphine) react to give [(SePh)₂Cd₂Br₂(PCh₃)₂] (1), [(SePh)₂Cd₂I₂(PCh₃)₂] (2) and [(SePh)₇Cd₄Br(PCh₃)]_n (3). The new compounds are examples of Cd(II) clusters obtained starting from the cluster-forming reagents Cd(SePh)₂ and CdX₂ (X = Br, I) in the presence of variable amounts of PCh₃. While 1 and 2 are single, tetranuclear clusters, compound 3 attains polymeric adamantanoid cages linked through selenium bridges.

Full text of DOI:10.1016/j.poly.2010.02.023

Polyhedron 29 (2010) 1760–1763
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Polyhedron
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Synthesis, structural characterization and growth features of some (Ph)Se–Cd
cluster compounds (Ph = phenyl)
*
*
Ernesto Schulz Lang , Rafael Stieler, Gelson Manzoni de Oliveira
LMI – Laboratório de Materiais Inorgânicos, Departamento de Química, Universidade Federal de Santa Maria (UFSM), 97105-900 Santa Maria, RS, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Cd(SePh)2, CdBr2ꢀ4H2O/CdI2 and PCh3 (Ph = phenyl; PCh3 = tricyclohexylphosphine) react to give
[(SePh)2Cd2Br2(PCh3)2] (1), [(SePh)2Cd2I2(PCh3)2] (2) and [(SePh)7Cd4Br(PCh3)]n (3).
The new compounds are examples of Cd(II) clusters obtained starting from the cluster-forming
reagents Cd(SePh)2 and CdX2 (X = Br, I) in the presence of variable amounts of PCh3. While 1 and 2 are
single, tetranuclear clusters, compound 3 attains polymeric adamantanoid cages linked through selenium
bridges.
Received 1 October 2009
Accepted 15 February 2010
Available online 18 February 2010
Keywords:
Cd(II)-clusters
Cd(II)-selenolate clusters
Clusters growth
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
[Cd2(SePh)2I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3) (PCh3 =
tricyclohexylphosphine). The structural characterization of the
Clusters of the IIbꢁVI groups have become progressively impor-
tant due to their semiconductor potentialities, among other materi-
als and biological applications [1–4]. Since the chemistry of
adamantane-like mercury/cadmium–chalcogen cages has been also
extensively studied [5–11], in recent reports we have discussed the
use of mercury bis-phenylselenolate/tellurolate, Hg(EPh)2 (E = Se,
Te), as efficient start for the synthesis of ternary clusters and poly-
mers [12–16].
It is well known that metal chalcogenide clusters and deriva-
tives can show variable sizes and shapes, whether concerning to
single clusters like [(PhTe)16Ag4Hg6Py4] (Ph = phenyl; Py = pyri-
dine) [17] or regarding to bulkier, polymeric clusters like [Hg5Cl3-
new compounds will be also presented, together with a brief com-
parative discussion on their formation and growth.
2. Experimental
2.1. General
All reactions were carried out under dry Ar. Solvents were puri-
fied and dried by standard procedures and freshly distilled before
use. Cadmium bromide tetrahydrate, cadmium iodide and tricyclo-
hexylphosphine were purchased from Sigma AldrichÒ. Cd(SePh)2
[20] was prepared according to literature procedures [21]. Elemen-
tal analyses were made using a FlashEA 1112 device. The synthetic
procedures can be summarized in the form of the chemical Eqs. (a)
and (b) below,
(SePh)7]n and [Hg7Br3(SePh)11]n [18].
In the study of the architecture of nanocrystals building blocks,
Cheon et al. [19] elected ‘‘time”, ‘‘temperature” ‘‘capping mole-
cules” and ‘‘kinetic energy barrier, (D
G#), as the parameters whose
CdðSePhÞ2 þCdX2 þ2PCy3 ! ½Cd2ðSePhÞ2X2ðPCy3Þ2ꢂ ðX ¼ Brð1Þ; Ið2Þ
ðaÞ
interaction should influence the growth pattern of nanocrystals.
Although nanocrystals and nanoclusters are different species,
and this report does not address nanoclusters, we have observed
that some parameters discussed by Cheon et al. [19] for nanocrystals
4CdðSePhÞ2 þCdBr2 þPCy3 ! ½Cd4ðSePhÞ7BrðPCy3Þꢂnð3ÞþðCdSePhBrÞn ðbÞ
In the case of 3, the equation does not correspond to the actu-
ally used stoichiometry (2:1:2), since the excess of Cd(SePh)2 leads
to the polymerization of the main product in the solvothermal
reaction.
seem to be also valid in the managing of the growth of (l-Se)Cd(II)
clusters. We report now the use of cadmium bis-phenylselenolate,
Cd(SePh)2, plus CdX2 (X = Br, I), in the synthesis of the new tetranu-
clear and adamantanoid shaped clusters [Cd2(SePh)2Br2(PCh3)2] (1),
2.2. Preparation of [Cd2(SePh)2Br2(PCh3)2] (1)
A
mixture of CdBr2ꢀ4H2O (0.034 g, 0.1 mmol), Cd(SePh)2
* Corresponding authors. Tel.: +55 3220 8980; fax: +55 3220 8031 (G.M. de
Oliveria).
E-mail addresses: eslang@base.ufsm.br (E.S. Lang), manzonideo@smail.ufsm.br
(G.M. de Oliveira).
(0.042 g, 0.1 mmol), PCh3 (0.056 g, 0.2 mmol) in 8 mL of methanol
was heated at 130 °C for 1 h in a 12 mL stainless steel sealed
reactor. Thereafter the reactor was cooled down slowly to room
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.02.023

E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763
1761
Table 1
Crystal data and structure refinement for 1, 2 and 3.
1
2
3
Empirical formula
Formula weight
T (K)
C48H76Br2Cd2P2Se2
1257.57
293(2)
C48H76Cd2I2P2Se2
1351.55
296(2)
C60H68BrCd4PSe7
1902.34
293(2)
Radiation, k (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
Mo K
a
, 0.71073
Mo K
a
, 0.71073
Mo Ka, 0.71073
monoclinic
P21/n
triclinic
triclinic
ꢀ
ꢀ
P1
P1
10.2012(4)
10.8207(4)
12.2261(5)
72.776(2)
88.663(2)
83.995(3)
1281.93(9)
1
10.3511(10)
10.7551(12)
12.1186(13)
101.577(8)
87.752(6)
84.188(6)
1280.2(2)
1
20.8440(3)
14.1347(2)
22.2968(3)
90
98.3040(10)
90
6500.29(16)
4
1.944
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
DCalc (g cmꢁ1
)
1.629
3.900
628
1.753
3.551
664
Absorption coefficient (mm1)
F (0 0 0)
5.885
3632
Crystal size (mm)
h (°)
Index range
0.355 ꢃ 0.265 ꢃ 0.08
0.11 ꢃ 0.1 ꢃ 0.09
1.99–27.56
ꢁ13 6 h 6 13, ꢁ13 6 k 6 13,
ꢁ15 6 l 6 15
23 064
0.22 ꢃ 0.082 ꢃ 0.055
1.71–30.06
ꢁ29 6 h 6 26, ꢁ19 6 k 6 17,
ꢁ31 6 l 6 30
65 510
2.22–27.22
ꢁ10 6 h 6 13, ꢁ13 6 k 6 13, ꢁ15 6 l 6
15
14 708
Reflections collected
Reflections unique (Rint
Completeness to theta maximum (%) 99.3
)
5685 (0.0403)
5846 (0.0687)
98.7
18 992 (0.0428)
99.6
Absorption correction
Maximum and minimum
transmission
gaussian
0.7455 and 0.5566
multi-scan
0.7456 and 0.6557
multi-scan
0.746 and 0.5784
Refinement method
full-matrix least-squares on F2
5685/0/254
1.037
full-matrix least-squares on F2
5846/0/241
1.061
full-matrix least-squares on F2
18 992/0/658
1.031
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
Final R indices [I > 2
r
(I)]
R1 = 0.0443, wR2 = 0.0974
R1 = 0.0838, wR2 = 0.1129
1.926 and 0.898
R1 = 0.0502, wR2 = 0.1182
R1 = 0.0847, wR2 = 0.1352
3.828 and 1.918
R1 = 0.0419, wR2 = 0.0991
R1 = 0.1108, wR2 = 0.1364
1.256 and 1.126
R indices (all data)
Largest diff. peak and hole (e Å3)
temperature (4 h) and white crystals suitable for X-ray analysis
were obtained. Yield: 82% based on Cd(SePh)2. Melting point:
178ꢁ180 °C. Anal. Calc. for C48H76Br2Cd2P2Se2 (1257.62): C,
The crystal structures were solved by direct methods using SHELXS
[22]. Subsequent Fourier-difference map analyses yielded the
positions of the non-hydrogen atoms. Refinements were carried
out with SHELXL package [22]. All refinements were made by full-
matrix least-squares on F2 with anisotropic displacement param-
eters for all non-hydrogen atoms. Hydrogen atoms were included
in the refinement in calculated positions. Crystal data and more
details of the data collections and refinements are contained in
Table 1.
45.84; H, 6.09. Found: C, 45.90; H, 5.82%. IR (KBr): 3064 [
ms(CꢁH)];
2932 [mas(CH2)]; 2849 [ms(CH2)]; 1573, 1472, 1446 [ms(C@C)]; 1069,
1020 [dip(C=CꢁH)]; 737, 690 [dop(C=CꢁH)]; 462 cmꢁ1 [dop(C@C–
C)].
2.3. Preparation of [Cd2(SePh)2I2(PCh3)2] (2)
According to the preparation of 1, with CdI2 (0.037 g, 0.1 mmol)
in the place of CdBr2ꢀ4H2O. White crystals were obtained. Yield:
85% based on Cd(SePh)2. Melting point: 216ꢁ218 °C. Anal. Calc.
for C48H76I2Cd2P2Se2 (1351.62): C, 42.65; H, 5.67. Found: C,
3. Results and discussion
The X-ray crystal data and the experimental conditions for the
analyses of the complexes [Cd2(SePh)2Br2(PCh3)2] (1), [Cd2(SePh)2-
I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3), are given in Table 1.
Table 2 presents selected bond distances and angles for the title
compounds. Figs. 1 and 2 represent the dimeric assembly of the
unit cells [CdSePhXPCh3] (X = Br, I) and the resulting configurations
of compounds 1 and 2. Fig. 3 shows the adamantanoid structure of
the unit cell of 3, and Fig. 4 displays the polymeric arrangement of
42.93; H, 5.37%. IR (KBr): 3063 [
m
s(CꢁH)]; 2932 [
mas(CH2)]; 2848
[
m
s(CH2)]; 1572, 1472, 1446 [
m
s(C@C)]; 1069, 1020 [dip(C=CꢁH)];
736, 689 [dop(C=CꢁH)]; 461 cmꢁ1 [dop(C@C–C)].
2.4. Preparation of [Cd4(SePh)7Br(PCh3)] (3)
According to the preparation of 1, with 0.084 g (0.2 mmol) of
Cd(SePh)2. White crystals were also obtained. Yield: 53% based
on Cd(SePh)2. Melting point: 185ꢁ187 °C. Anal. Calc. for
C60H68BrCd4PSe7 (1902.44): C, 37.88; H, 3.60. Found: C, 38.15; H,
3, achieved through (Ph)Se-l(CdxCdy) bridging bonds between the
adamantane-like moieties.
The association in pairs of the monomeric units
[CdSePhXPCh3] {X = Br (1), I (2)} leads to a distorted tetrahedral
configuration of the Cd(II) centers, with the bond distances rang-
ing within 2.5380(7) (CdꢁBr)ꢁ2.7449(7) Å (CdꢁSe0) in 1, and
2.5666(15) (CdꢁP)ꢁ2.7484(9) Å (CdꢁSe) in 2. In both dimeric
compounds the SeꢁCdꢁSe0ꢁCd0 bonds achieve a quadratic ring
with an inversion center. In the adamantanoid structure of 3
3.41%. IR (KBr): 3045 [
m
s(CꢁH)]; 2930 [
mas(CH2)]; 2849 [ms(CH2)];
1573, 1472, 1434 [ms(C@C)]; 1068, 1019 [dip(C@C–H)]; 735, 688
[dop(C@C–H)]; 462 cmꢁ1 [dop(C@CꢁC)].
2.5. X-ray structural determination
all the selenium atoms attain
l2-bridges linking the four cad-
Data were collected with a Bruker APEX II CCD area-detector
mium centers, with a medium distance of 2.65 Å; one bromide
diffractometer and graphite-monochromatized Mo K
a radiation.
ligand and one P(Ch3) group accomplish the distorted tetrahedral

1762
E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763
Table 2
Selected bond lengths (Å) and angles (°) for 1, 2, and 3.
Complex 1
Bond lengths
CdꢁBr
Cd1ꢁBr
2.5580(7)
2.6476(7)
2.6621(8)
2.6652(7)
2.6616(7)
2.6309(7)
2.6431(7)
2.6439(7)
Cd1ꢁSe4
2.5380(7)
2.5737(12)
2.6786(7)
2.7449(7)
Cd1ꢁSe7
CdꢁP
Cd1ꢁSe2
CdꢁSe
Se1ꢁCd4
CdꢁSe0
Cd4ꢁSe50
Bond angles
BrꢁCdꢁP
BrꢁCdꢁSe
PꢁCdꢁSe
BrꢁCdꢁSe0
PꢁCdꢁSe0
SeꢁCdꢁSe0
CdꢁSeꢁCd0
Complex 2
Bond lengths
PꢁCd
Cd4ꢁSe7
116.64(4)
107.69(2)
118.26(3)
120.43(3)
99.57(3)
92.24(2)
87.76(2)
Cd4ꢁSe6
Bond angles
Se4ꢁCd3ꢁSe6
Se4ꢁCd3ꢁSe5
Se6ꢁCd3ꢁSe5
Se4ꢁCd3ꢁSe3
Se6ꢁCd3ꢁSe3
Se5ꢁCd3ꢁSe3
PꢁCd2ꢁSe2
PꢁCd2ꢁSe3
Se2ꢁCd2ꢁSe3
PꢁCd2ꢁSe1
Se2ꢁCd2ꢁSe1
Se3ꢁCd2ꢁSe1
BrꢁCd1ꢁSe4
BrꢁCd1ꢁSe7
Se4ꢁCd1ꢁSe7
BrꢁCd1ꢁSe2
Se4ꢁCd1ꢁSe2
Se7ꢁCd1ꢁSe2
Cd4ꢁSe1ꢁCd2
Cd2ꢁSe2ꢁCd1
Cd3ꢁSe4ꢁCd1
Cd400ꢁSe5ꢁCd3
Cd2ꢁSe3ꢁCd3
Se50ꢁCd4ꢁSe7
Se50ꢁCd4ꢁSe6
Se7ꢁCd4ꢁSe6
Se50ꢁCd4ꢁSe1
Se7ꢁCd4ꢁSe1
Se6ꢁCd4ꢁSe1
122.65(2)
118.50(2)
105.31(2)
100.10(2)
109.01(2)
97.83(2)
114.05(4)
110.15(4)
107.24(2)
108.11(4)
108.58(2)
108.59(2)
108.10(3)
108.11(3)
124.99(2)
109.71(2)
113.69(2)
90.83(2)
105.73(2)
109.93(2)
104.33(2)
121.06(2)
111.29(2)
105.46(2)
97.65(2)
2.5666(15)
2.7484(9)
2.6851(8)
2.7182(7)
SeꢁCd
CdꢁSe0
CdꢁI
Bond angles
Cd0ꢁSeꢁCd
PꢁCdꢁSe0
PꢁCdꢁI
86.55(3)
118.10(4)
116.78(4)
107.08(2)
98.91(4)
93.45(3)
120.78(2)
Fig. 2. Dimeric assembly of [Cd2(SePh)2I2(PCh3)2] (2). Symmetry transformations
used to generate equivalent atoms: (0) ꢁx + 1, ꢁy + 1, ꢁz.
Se0ꢁCdꢁI
PꢁCdꢁSe
Se0ꢁCdꢁSe
IꢁCdꢁSe
Complex 3
Bond lengths
Cd3ꢁSe4
Cd3ꢁSe6
Cd3ꢁSe5
Cd3ꢁSe3
Cd2ꢁP
2.6179(7)
2.6235(7)
2.65507)
2.6641(7)
2.5810(15)
2.6458(7)
2.6480(7)
2.6742(7)
122.85(2)
122.67(2)
107.05(2)
102.46(2)
Cd2ꢁSe2
Cd2ꢁSe3
Cd2ꢁSe1
Symmetry transformations used to generate equivalent atoms: 1: (0) ꢁx + 1, ꢁy + 2,
ꢁz + 1; 2: (0) ꢁx + 1, ꢁy + 1, ꢁz; 3: (0) ꢁx + 1.5, y + 0.5, ꢁz + 1.5; (00) ꢁx + 1.5, y ꢁ 0.5,
ꢁz + 1.5.
Fig. 3. Molecular structure of [Cd4(SePh)7Br(PCh3)] (3).
are linked as well through Se bonds (bridges) which measure
2.6309(7) Å.
The main difference in the synthesis of compound 3, if com-
pared with the syntheses of 1 and 2, is the use of 0.2 mmol of
Cd(SePh)2 instead of 0.1 mmol. Thus, the amount of the effective
cluster-forming reagent was duplicated, hence the amount of the
co-ligand PCh3 was relatively reduced to the half. In consequence,
compound 3 results from the polymerization of 13-membered ada-
mantanoid moieties, in contrast with the tetranuclear clusters 1
and 2.
Finally, the title compounds 1, 2 and 3 are not examples of
Fig. 1. Structure of [Cd2(SePh)2Br2(PCh3)2] (1). Symmetry transformations used to
generate equivalent atoms: (0) ꢁx + 1, ꢁy + 2, ꢁz + 1.
‘‘giant” chalcogenide tetrahedral nanoclusters like [Cd32S14
-
2ꢁ
(SPh)38
]
[23] or [Cd32Se14(SePh)36(L)4] (L = OPPh3, OC4H8) [24],
among others. In our case, two main factors seem to have pre-
vented the growth of the cluster products, and, specially, in the
case of 3, the fusion of the adamantanoid cages, instead of their
polymerization: the use of two sources of Cd2+ ions and the
configuration of Cd1 and Cd2, respectively, with distances of
2.5580(7) (Cd1ꢁBr) and 2.5810(15) Å (Cd2ꢁP). The adamantanes

E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763
1763
Acknowledgment
This work was supported with funds from PRONEX-CNPq/FA-
PERGS (Brazil).
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4. Supplementary data
CCDC 730892, 730893 and 745060 contains the supplementary
crystallographic data for 1, 2 and 3. These data can be obtained free
of charge via 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.