Syntheses and crystal structures of the two new polychalcogenides

Article abstract of DOI:10.1515/znb-2004-0602

The solvothermal reaction of MnCl₂·4 H₂O, K₂Se₃ and Se in trans-cyclohexane-1,2-diamine (chxn) at 433 K yields dark blue crystals of [Mn(chxn)₃]Se₆ (1), and the reaction of MnCl₂·4 H₂O, K₂Se ₃ and Te under similar conditions gives dark blue crystals of [Mn(chxn)₃]₂[H₂chxn](TeSe₂) ₂Se (2). While compound (1) crystallises in the orthorhombic space group Pbcn with the lattice parameters a = 13.7017(9), b = 19.9073(8) and c = 10.8058(5) A?, compound (2) crystallises in the monoclinic space group P2₁ with the lattice parameters a = 9.4396(6), b = 24.2450(2), c = 12.8170(8) A? and β = 91.6(1)°. In both structures discrete complex cations and polychalcogenide anions are found. In (1) the Se6 ^2- anions form a pseudo-layer arrangement with nearly rectangular pores. The complex cations are encapsulated by the arrangement of the Seg ^2- anions. Some short distances between the amino groups of the ligands and the anions indicate weak hydrogen bonding. In compound (2) two independent [Mn(chxn)₃]²⁺ and one unique H₂chxn dications, two unique TeSe₂^2- as well as one Se ^2- dianion coexist. The two complex cations exhibit different conformations. One of the two TeSe₂^2- anions has the di-protonated chxn molecule in the neighbourhood and short Se?H separations indicate weak hydrogen bonding. The isolated Se^2- ion is located above the ring of the di-protonated trans-cyclohexane-1,2-diamine molecule and again a short Se?H separation may be due to a weak hydrogen bond. Compound (1) decomposes in a single step when heated in an Ar atmosphere. In contrast, the thermal decomposition of compound (2) is complex and at least five different steps can be identified.

Full text of DOI:10.1515/znb-2004-0602

Syntheses and Crystal Structures of the Two New Polychalcogenides
[Mn(C6H14N2)3]Se6 and [Mn(C6H14N2)3]2[C6H16N2](TeSe2)2Se
Frank Wendland, Christian Na¨ther, and Wolfgang Bensch
Institut fu¨r Anorganische Chemie, Olshausenstraße 40, D-24118 Kiel, Germany
Reprint requests to Prof. Dr. Wolfgang Bensch. Fax: +49(0)431 880 1520.
E-mail: wbensch@ac.uni-kiel.de
Z. Naturforsch. 59b, 629 – 634 (2004); received February 11, 2004
Dedicated to Prof. Dr. G.-V. Ro¨schenthaler on the occasion of his 60th birthday
The solvothermal reaction of MnCl2 · 4 H2O, K2Se3 and Se in trans-cyclohexane-1,2-diamine
(chxn) at 433 K yields dark blue crystals of [Mn(chxn)3]Se6 (1), and the reaction of MnCl2 · 4 H2O,
K2Se3 and Te under similar conditions gives dark blue crystals of [Mn(chxn)3]2[H2chxn](TeSe2)2Se
(2). While compound (1) crystallises in the orthorhombic space group Pbcn with the lattice parame-
˚
ters a = 13.7017(9), b = 19.9073(8) and c = 10.8058(5) A, compound (2) crystallises in the mono-
˚
clinic space group P21 with the lattice parameters a = 9.4396(6), b = 24.2450(2), c = 12.8170(8) A
and β = 91.6(1)◦. In both structures discrete complex cations and polychalcogenide anions are found.
2−
In (1) the Se6 anions form a pseudo-layer arrangement with nearly rectangular pores. The com-
plex cations are encapsulated by the arrangement of the Se62− anions. Some short distances between
the amino groups of the ligands and the anions indicate weak hydrogen bonding. In compound (2)
2−
two independent [Mn(chxn)3]2+ and one unique H2chxn dications, two unique TeSe2 as well as
one Se2− dianion coexist. The two complex cations exhibit different conformations. One of the two
2−
TeSe2 anions has the di-protonated chxn molecule in the neighbourhood and short Se···H sep-
arations indicate weak hydrogen bonding. The isolated Se2− ion is located above the ring of the
di-protonated trans-cyclohexane-1,2-diamine molecule and again a short Se···H separation may be
due to a weak hydrogen bond. Compound (1) decomposes in a single step when heated in an Ar atmo-
sphere. In contrast, the thermal decomposition of compound (2) is complex and at least five different
steps can be identified.
Key words: Solvothermal Synthesis, Polychalcogenides, Selenides, Telluroselenides,
Thermal Decomposition
Introduction
polychalcogenide anions formed. One would assume
that the size and arrangement of the ammonium
cations or of complex cations should affect the na-
ture of the polychalcogenide anions. In 1987 Dehnicke
et al. [4] showed that isolated tetraalkylammonium
cations (N(C2H5)4, R–N(CH3)3, R = C16H33, C14H29,
C12H25) had no predictable effect on the size and struc-
ture of the polyselenide anions in the crystalline prod-
ucts. Judging by the wealth of hexaselenides reported
For the synthesis of polychalcogenide anions the
solvothermal method is a suitable route. In selenium
and tellurium chemistry, e. g., reacting suitable start-
ing compounds at temperatures ranging from 363–
455 K under an autogenous pressure of 105 – 106 Pa
for several days in a Teflon-lined autoclave or a
glass ampoule can give pure and mixed polyselenides
and polytellurides. Examples reported in the litera-
ture are [Mn(en)3]Se3 and [Mn(en)3]TeSe2 [1] and
[Mn(en)3]Te4 [2, 3]. These compounds were synthe-
sised using ethylene-1,2-diamine (en) as the solvent
and chelating amine.
2−
in the literature [4 – 8] the Se6 anion seems to re-
present the most stable of the polyselenide anions.
2−
It is noteworthy that no Sen anion longer than the
2−
nonaselenide Se9 has been synthesised yet. We note
that the two compounds presented here are the first
[Mn(chxn)3]2+ complexes and the first chalcogenides
with a [M(chxn)3]n+ counter cation.
One aspect investigated during our work is the
influence of the cation size onto the length of the
c
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F. Wendland et al. · Two New Polychalcogenides
◦
˚
Table 1. Selected bond lengths [A] and angles [ ] in
[Mn(chxn)3]Se6 (1). Estimated standard deviations are given
in parentheses.
C13
C12
C11
Se3a
Se3
Se(1)–Se(2)
Se(3)–Se(3A)
Mn–N(1)
2.3129(5) Se(1)–Se(3)
2.3602(8)
2.3403(6)
N2
N1
C1
Mn
2.238(3)
2.246(2)
2.322(2)
Mn–N(1A)
Mn–N(2)
Mn–N(3A)
2.238(3)
2.246(2)
2.322(2)
C2
C3
C23
Se1
Mn–N(2A)
Mn–N(3)
Se2
N3
C21
C22
Se(2)–Se(1)–Se(3) 108.32(2) Se(1)–Se(3)–Se(3A) 106.08(2)
N(1)–Mn–N(1A)
N(1A)–Mn–N(2A)
N(1A)–Mn–N(2)
N(1)–Mn–N(3)
N(2A)–Mn–N(3)
N(1)–Mn–N(3A)
N(2A)–Mn–N(3)
N(3)–Mn–N(3A)
155.2(2)
99.1(1)
100.1(1)
88.9(1)
165.1(1)
75.9(1)
89.4(1)
104.4(2)
N(1)–Mn–N(2A)
N(1)–Mn–N(2)
N(2A)–Mn–N(2)
N(1A)–Mn–N(3)
N(2)–Mn–N(3)
N(1A)–Mn–N(3)
N(2)–Mn–N(3A)
100.1(1)
99.1(1)
77.6(2)
75.9(1)
89.4(1)
88.9(1)
165.1(1)
2−
Fig. 1. The Se6 anion (left) and the [Mn(chxn)3]2+ cation
(right) in compound 1 with atomic labelling. (Hydrogen
atoms are omitted for clarity.)
the structure can clearly be seen in the arrangement of the
molecules within the unit cell. Experimental details of data
collections and selected refinement results are summarised
in Table 3.
Experimental Section
Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as supple-
mentary publication no. CCDC 230932 for [Mn(chxn)3]Se6
and CCDC 230931 for [Mn(chxn)3]2[H2chxn](TeSe2)2Se.
Copies of the data can be obtained, free of charge,
on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK. (fax: +44-(0)1223-336033 or email:
deposit@ccdc.cam.ac.uk).
Syntheses
Dark blue plate like crystals of [Mn(chxn)3]Se6 (1) (esti-
mated yield 60% based on Mn) were obtained from the reac-
tion of 0.198 g MnCl2 ·4H2O, 0.315 g K2Se3 and 0.079 g Se
(molar ratio 1:1:3) in 2 ml of trans-cyclohexane-1,2-diamine
at 433 K heated for 7 d. The product was washed with ethanol
and dried in a vacuum. The crystals are not stable on air and
decompose within 2 weeks.
The reaction of 0.06 g MnCl2 · 4H2O, 0.095 g K2Se3 and
0.115 g Te (molar ratio 1:1:3) in 2 ml of trans-cyclohexane-
1,2-diamine at 433 K for 7 d gave dark blue polyhedra of 2
(estimated yield 70% based on Mn). The product was washed
with ethanol and dried in a vacuum. Using K2Se3 and Te,
crystals of [Mn(chxn)3]2[H2chxn](TeSe2)2Se (2) were also
formed. The compound is not stable on air and decomposes
within 2 weeks. The composition was confirmed by C, H, N
analysis and AAS (C calculated 32.31%, found 32.15%; H
calculated 6.46%, found 6.23%; N calculated 12.56%, found
12.93%, C:N ratio calculated 2.57, found 2.49; calculated
Mn:Se ratio 1:2.5, found 1:2.57).
X-ray powder diffractometry
The X-ray powder patterns were recorded with a Siemens
D5000 (Cu-Kα radiation, λ = 1.54056 A) in Bragg-Brentano
geometry.
˚
Thermal analysis
The DTA-TG data were recorded using a Netzsch STA
429 instrument. All measurements were performed under an
argon atmosphere in alumina crucibles using Al2O3 as the
inert reference. Heating rate: 3 K/min.
Results and Discussion
Structure refinement details
Crystal structures
Single crystal X-ray diffractometry: The intensities were
collected using a STOE IPDS I diffractometer (λ =
Thecompoundtris(trans-cyclohexane-1,2-diamine)-
manganese-hexaselenide (1) crystallises in the or-
thorhombic space group Pbcn with four formula units
in the unit cell. The crystal structure consists of iso-
˚
0.7107 A). The data were corrected for Lorentz and
polarisation effects and face indexed absorption correc-
tions were applied. All non-hydrogen atoms were re-
fined with anisotropic displacement parameters. The hy-
drogen atoms were positioned with idealised geometry and
refined with fixed isotropic displacement parameters. In
[Mn(chxn)3]2(TeSe2)2Se·H2chxn (2) the N(13) atom is dis-
ordered into two positions and was refined using a split
model. The crystal was a racemic twin and refined with
2−
lated [Mn(chxn)3]2+ cations and Se6 anions each of
these being located on centres of inversion. The Mn2+
ion is in an octahedral environment of six nitrogen
atoms of three amine molecules with Mn−N distances
˚
between 2.238(3) and 2.322(2) A (Fig. 1, Table 1).
a BASF parameter of 0.35(1). The non-centrosymmetry of The Mn-N bond lengths are in the range reported in
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F. Wendland et al. · Two New Polychalcogenides
631
C53
C14
C12
C54
C55
C13
C15
C52
C51
N11
C56
N12
C11
N4
C16
C5
N7
a
c
N2
C32
C31
C6
C4
N3
Mn2
N9
C3
C33
C34
Mn1
C1
C36
C2
N8
N1
N5
C35
N10
C41
C21
C46
N6
C42
C45
C43
C22
C44
C26
C25
C23
C24
Fig. 2. The pseudo-layers formed by intermolecular
Fig. 4. The two cations in [Mn(C6H14N2)3]2[C6H16N2]
(TeSe2)2Se (2) with atomic labelling.
2−
Se(1)···Se(1) contacts between neighbouring Se6 anions
in compound 1. Dotted lines are the long Se-Se separations.
plane of the pores and the ligands pointing outwards
(Fig. 3). The layers are stacked perpendicular to [010]
˚
with a shortest interlayer separation of 9 A. The ter-
minal Se(1) atom has two relatively short contacts to H
˚
atoms of the amino groups of 2.61 and 2.66 A with cor-
responding angles of 158.6◦ and 170.5◦. The arrange-
ment of the cations and anions may be viewed as an en-
capsulation of the [Mn(chxn)3]2+ cations by the Se6
anions.
2−
Compound 2 crystallises in the monoclinic space
group P21 with two formula units in the cell. Two crys-
tallographically independent [Mn(chxn)3]2+ cations,
2−
two crystallographically independent Se6
anions,
one selenide anion and one di-protonated ligand are
found, and all are located in general positions. The
two crystallographically independent Mn2+ cations are
each sixfold coordinated by the nitrogen atoms of
three 1,2-cyclohexanediamine molecules (Fig. 4), and
the complex cations show the lel3-λ(λδδ) and lel3-
(λλδ) conformation. The Mn–N distances are be-
Fig. 3. Crystal structure of compound 1 with view along the
c-axis. (Hydrogen atoms are omitted for clarity.) Dotted lines
indicate the long Se-Se contacts.
the literature [9 – 11]. The N-Mn-N angles indicate a
relatively strong distortion from ideal octahedral ge-
ometry (Table 1). The Se–Se bond lengths within the
˚
tween 2.227(5) and 2.284(5) A for Mn(1) and range
2−
˚
from 2.254(5) to 2.291(5) A for Mn(2), being compa-
Se6 chain (Fig. 1) vary from 2.3129(5) (terminal
˚
rable with the values found in 1 and in [9 – 11]. Again,
the N-Mn-N angles indicate a rather strong distortion
of the octahedral environment (Table 2). The Se–Te
Se(1)–Se(2)) to 2.3602(8) A (internal Se(3)–Se(3a)).
The angles are 108.32(2)◦ for Se(2)–Se(1)–Se(3) and
106.08(2)◦ for Se(1)–Se(3)–Se(3a). These values are
comparable with those found in other hexa-selenides
[5 – 8]. Between the anions the shortest separation is
˚
distances between 2.4781(8) and 2.4888(8) A and Se–
Te–Se angles of 106.44(3) and 109.41(3)◦ (Table 2)
2−
˚
found in the two distinct V-shaped TeSe2 anions are
3.618 A (Se(1)-Se(3)) which is slightly smaller than
2−
˚
in the range observed for other isolated TeSe2 an-
the sum of the van der Waals radii (3.80 A). When
ions [1, 12].
these Se···Se contacts are taken into account two-
2−
dimensional layers with large nearly rectangular pores
The shortest separations between the TeSe2 an-
˚
formed by rings of 14 Se atoms present in the (010) ions amount to 5.529 (Se(2)···Se(3)) and 5.480 A
plane (Fig. 2). The dimensions of the pores are about (Se(1)···Se(4)) which are shorter than the distance of
2+
˚
˚
6.029 A found in [Mn(en)3]TeSe2 [1]. The two differ-
8.9·8.5 A. The pores are filled with the [Mn(chxn)3]
cations with the central Mn2+ ion residing within the ent TeSe2 anions are stacked in rods along [100],
2−
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F. Wendland et al. · Two New Polychalcogenides
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˚
Table 2. Selected bond lengths (A) and angles [ ] in
[Mn(chxn)3]2[H2chxn](TeSe2)2Se (2). Estimated standard
deviations are given in parentheses.
Te(1)–Se(1)
Te(2)–Se(4)
Mn(1)–N(5)
Mn(1)–N(2)
Mn(1)–N(1)
Mn(2)–N(12)
Mn(2)–N(11)
Mn(2)–N(7)
2.478(1)
2.483(1)
2.227(5)
2.262(5)
2.275(5)
2.254(5)
2.261(5)
2.286(5)
Te(1)–Se(2)
Te(2)–Se(3)
Mn(1)–N(6)
Mn(1)–N(4)
Mn(1)–N(3)
Mn(2)–N(8)
Mn(2)–N(10)
Mn(2)–N(9)
2.480(1)
2.489(1)
2.256(5)
2.265(6)
2.284(5)
2.258(5)
2.272(5)
2.291(5)
Se(1)–Te(1)–Se(2) 106.44(3) Se(4)–Te(2)–Se(3)
109.41(3)
92.6(2)
170.4(2)
92.4(2)
95.8(2)
90.3(2)
95.8(2)
98.1(2)
76.7(2)
N(5)–Mn(1)–N(6)
N(5)–Mn(1)–N(6)
N(6)–Mn(1)–N(2)
N(6)–Mn(1)–N(4)
N(5)–Mn(1)–N(1)
N(2)–Mn(1)–N(1)
N(5)–Mn(1)–N(3)
N(2)–Mn(1)–N(3)
N(1)–Mn(1)–N(3)
79.3(2)
79.3(2)
93.0(2)
170.3(2)
97.3(2)
76.9(2)
89.2(2)
97.6(2)
170.3(2)
N(5)–Mn(1)–N(4)
N(5)–Mn(1)–N(2)
N(5)–Mn(1)–N(4)
N(2)–Mn(1)–N(4)
N(6)–Mn(1)–N(1)
N(4)–Mn(1)–N(1)
N(6)–Mn(1)–N(3)
N(4)–Mn(1)–N(3)
N(12)–Mn(2)–N(8) 169.4(2)
N(12)–Mn(2)–N(11)
N(12)–Mn(2)–N(10)
N(11)–Mn(2)–N(10) 170.5(2)
N(8)–Mn(2)–N(7)
N(10)–Mn(2)–N(7)
N(8)–Mn(2)–N(9)
N(10)–Mn(2)–N(9)
79.0(2)
93.2(2)
N(8)–Mn(2)–N(11)
N(8)–Mn(2)–N(10)
N(12)–Mn(2)–N(7)
N(11)–Mn(2)–N(7)
N(12)–Mn(2)–N(9)
N(11)–Mn(2)–N(9)
N(7)–Mn(2)–N(9)
91.7(2)
96.5(2)
96.9(2)
91.3(2)
92.4(2)
96.5(2)
168.9(2)
78.2(2)
95.0(2)
93.7(2)
78.3(2)
Fig. 5. Packing of the di-protonated trans-cyclohexane-1,2-
2−
diamine molecules, the TeSe2 and Se2− anions showing
Se···H contacts in compound (2). The nitrogen atom N13 is
disordered in two positions and the C-H hydrogen atoms are
omitted for clarity.
with an identical orientation within the rods and an al-
ternating orientation in neighbouring rods. The short-
est distance between the isolated Se2− anion and a Se
disordered and both orientations are energetically more
or less identical.
2−
˚
atom of the TeSe2 anion amounts to 5.978 A.
Charge neutrality of the compound requires that
the isolated trans-cyclohexane-1,2-diamine molecule
is di-protonated. The Se atoms of only one of the
Thermal properties
Single crystals of [Mn(chxn)3]Se6 were heated up
to 873 K in an argon atmosphere. The sample de-
composed in one step, accompanied by a mass loss
of 34.9% (calculated mass loss for the three amine
molecules is 39.3%). In the grey product obtained af-
ter the treatment MnSe could be identified with X-ray
powder diffraction. According to the C, N, H analy-
sis only traces of organic material are present. Hence,
it must be assumed that amorphous elemental Se is
present in the residue explaining the difference be-
tween the expected and measured mass change.
2−
TeSe2 anions (Te(1), Se(1), Se(2)) and the isolated
Se2− ion (Se(5)) have relatively short contacts to the H
atoms of the amino groups of the trans-cyclohexane-
1,2-diammonium cation. The arrangement of the an-
ions around the ammonium cation is displayed in
Fig. 5. All cations point into the same direction
which can be regarded as an evidence for the non-
centrosymmetry of the structure. Two of the three H
atoms of N(14) have a contact to one Se atom of one
2−
˚
˚
A SEM-EDX-analysis of the decomposition prod-
uct showed three different phases: octahedral-like crys-
tals with composition MnSe, ellipsoidal and shapeless
crystals which both are selenium-rich.
TeSe2 anion (Se(1)-H28N: 2.597 A; Se(2)-H29N:
2.533 A). As expected the H atoms point towards the
lone-pairs of Se(1) resp. Se(2). The third H atom makes
a short contact to the isolated Se2− anion (Se(5)-H30N:
˚
2.498 A). Obviously, there is no ammonium cation in
A more complex behaviour was found for [Mn
the neighbourhood of the second TeSe22− anion which (chxn)3]2[H2chxn](TeSe2)2Se. Upon heating single
can act as a donor for hydrogen bonds. Because the crystals in an argon atmosphere decomposition oc-
H atoms of N13 have no contacts to acceptors they are cured in at least five not well separated steps (Fig. 6),
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6900
5700
4500
Int.
(a.u.)
468 K
871 K
3300
564 K
2100
900
22
24
26
28
30
32
34
36
2 Theta / °
Fig. 7. X-ray powder patterns of the decomposition prod-
ucts of [Mn(chxn)3]2[H2chxn](TeSe2)2Se (2) after heating
the sample to 468 K (first trace), to 564 K (second trace) and
to 871 K. Note that the patterns are shifted on the intensity
scale for clarity.
Fig. 6. DTA-TG curves for [Mn(chxn)3]2[H2chxn]
(TeSe2)2Se (2) in argon atmosphere.
each step being accompanied by an endothermic sig-
nal in the DTA curve. The total mass loss of 45.9% is
about 10% lower than expected assuming a decompo- small alterations are seen compared to that obtained
sition according to equation (1) (expected: 56.3%).
after the first stop. Interestingly, in the pattern of the
residue obtained at 564 K the background is more flat
and two new reflections occur between 30 and 40◦
2θ which match well with the most intense peaks of
MnSe2. We note that the formation of MnSe2 and ele-
mental Te is known from the thermal decomposition
of [Mn(en)3]TeSe2 [1]. In addition, the intensity ra-
tio of the “doublet” around 28 – 30◦ 2θ has drastically
changed and the reflection at about 38.3◦ 2θ has disap-
peared. In the pattern of the grey material obtained at
871 K several reflections can be explained with crys-
talline MnSe, but the remaining peaks do not match
with Te, Se or other Mn chalcogenides. It cannot be
excluded that at this temperature reactions within the
genuine material lead to the formation of unknown Mn
compounds. From the literature it is known that the de-
composition of MnSe2 into MnSe starts at 863 K in
vacuum which takes between 2 and 5 days until com-
pletion. At 948 K complete decomposition was ob-
served [13].
[Mn(chxn)3]2[H2chxn](TeSe2)2Se
(1)
→ 2MnSe2 +2Te+H2Se ↑+7C6H14N2 ↑
To acquire more information about this complex ther-
mal decomposition, several experiments were con-
ducted where the heat treatment was stopped after each
reaction step. The resolution of individual steps is not
good and the assignment of distinct temperatures to
each step is somewhat arbitrary. The products were
analysed by X-ray powder diffractometry.
A selected region of the X-ray powder patterns
(XPD) recorded after quenching samples from 468 K,
564 K and 871 K are displayed in Fig. 7. The back-
ground of the patterns recorded below 564 K is
strongly modulated in the range from about 10 to 40◦
2θ. In this 2θ range the most intense reflections of
the different modifications of elemental Se and Te are
located. The main difficulty for a definite assignment
of the reflections is that different manganese selenides
and tellurides as well as elemental Se and Te show the
strongest reflections in the region between 20 and 40◦
2θ. In addition, the formation of crystalline Te/Se solid
solutions makes the assignment more difficult. There-
fore, we can only qualitatively discuss the changes
of the X-ray powder patterns. After the first thermal
event (468 K) the XPD shows the reflections of el-
emental Te and one intense peak at about 28.3◦ 2θ
which cannot be explained considering simple com-
pounds like MnTe, MnSe, Se or MnSe2. In the XPD
In summary, the decomposition process of 2 is
complex with the experimental mass loss significantly
smaller than expected. The changes in the XPD pro-
vide also evidence for the complex nature of the ther-
mal reactions. Further experiments using mass spec-
trometry are required to acquire a better understanding
of the thermal degradation of the material.
In the introduction we mentioned that one aim of
our study is the investigation of the influence of the
size of the cation onto the polychalcogenide chain
of the reactions stopped after 475 and 500 K only length. Using the in situ formed [Mn(en)3]2+ cation
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634
F. Wendland et al. · Two New Polychalcogenides
Table 3. Crystallographic data, details of the data collec-
tion and selected results of the structure refinement for
[Mn(chxn)3]Se6 (1) and [Mn(chxn)3]2[H2chxn](TeSe2)2Se
(2). Estimated standard deviations are given in parentheses.
and applying K2Se3/Se or K2Te3/Se mixtures, well
2−
2−
separated Se3
resp. TeSe2
anions are observed
in the products. Under similar conditions and using
K2Te3/Te as the chalcogenide source, the compound
2−
[Mn(chxn)3]Se6 (1) [Mn(chxn)3]2[H2chxn]
(TeSe2)2Se (2)
[Mn(en)3]Te4 is formed with Te4
anions which
form infinite chains through interchain interactions [1].
With the larger [Mn(chxn)]2+ cation the reaction with
K2Se3/Se leads to the formation of [Mn(chxn)3]Se6
˚ ˚
Lattice parameters
a = 13.7017(9) A a = 9.4396(6) A
˚
˚
b = 19.9073(8) A b = 24.2450(2) A
˚
˚
c = 10.8058(5) A c = 12.8170(8) A
β = 91.6(1)
2−
with the Se6 anion which shows weak inter-anionic
3
interactions in a two-dimensional arrangement. With
the same cation, and using K2Te3/Se, the compound
[Mn(chxn)3]2[H2chxn](TeSe2)2Se is obtained with
isolated anions. Attempted syntheses with MnCl2 ·
4H2O, K2Te3/Te in a solution of chxn were unsuccess-
ful and only amorphous powders were formed. Hence,
the results of the present study as well as of previously
published work demonstrate that there is no simple re-
lation between cation size and the final polychalco-
genide chain lengths. It seems that besides the geo-
metrical factors hydrogen bonding cannot be neglected
even for the very weak Se···H and Te···H bonds.
˚
Unit cell volume/A
2947.4(3)
orthorhombic,
Pbcn
2932.3(3)
monoclinic,
P21
Crystal system,
space group
Formula units
per unit cell
4
2
Density (calculated)/ 1.963
1.768
g·.cm3
µ/mm−1
7.88
4.55
Scan range
Temperature of
data collection
No. refined
parameters
4◦ ≤ 2θ ≤ 56◦
150 K
3◦ ≤ 2θ ≤ 52◦
150 K
142
590
Reflections measured 15536
21249
10653
Independent
reflections
3421
Acknowledgements
We gratefully acknowledge the financial support by the
State of Schleswig-Holstein and the Deutsche Forschungs-
gemeinschaft (DFG).
Independent with
Fo > 4σ(Fo)
Rint
2908
9623
0.0774
0.1183/0.4270
0.0286
0.4207/0.6178
Min./max.
transmission
R1 (Fo > 4σ(Fo))
R1 (all)
0.0362
0.0447
0.0429
0.0480
wR2 (Fo > 4(Fo))
wR2 (−all)
0.0893
0.0938
1.57/−1.28
0.1175
0.1217
1.96/−1.13
3
˚
∆F/e /A
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