New heterobimetallic and polymeric selenocarboxylates derived from [M(SeC{O}Ph)4]- (M = Ga and In) as molecular precursors for ternary selenides

Article abstract of DOI:10.1021/ic0611286

(Et₃NH)[In(SeC{O}Ph)₄]·H₂O (1) along with heterobimetallic and polymeric metal selenocarboxylates, namely [NaGa-(SeC{O}Ph)₄] (2), [K(MeCN)₂Ga(SeC{O}Ph)₄] (3), [NaIn(SeC{O}Ph)₄] (

Full text of DOI:10.1021/ic0611286

Inorg. Chem. 2006, 45, 10147−10154
New Heterobimetallic and Polymeric Selenocarboxylates Derived from
-
[M(SeC
{O}Ph)4] (M ) Ga and In) as Molecular Precursors for Ternary
Selenides
Meng Tack Ng and Jagadese J. Vittal*
Department of Chemistry, National UniVersity of Singapore, Singapore 117543
Received June 22, 2006
(Et3NH)[In(SeC
(SeC Ph)4] (2), [K(MeCN)2Ga(SeC
CuIn(SeC Ph)4] CH2Cl2 (6), and [(Ph3P)2AgIn(SeC
either alkali metal ions (Na+ and K+) or group 11 metal ions (Cu(I) and Ag(I)) into the [M(SeC
Crystal structures determined by X-ray crystallography indicate that 3 and 5 have one-dimensional coordination
polymeric structures while 6 and 7 have an M( -Se)2In (M Cu, Ag) core. The thermal decomposition of these
{O
}
Ph)4]
‚
H2O (1) along with heterobimetallic and polymeric metal selenocarboxylates, namely [NaGa-
Ph)4] (3), [NaIn(SeC Ph)4] (4), [K(MeCN)2In(SeC Ph)4] (5), [(Ph3P)2-
Ph)4] CH2Cl2 (7), have been synthesized by incorporating
Ph)4]- anion.
{O}
{O}
{
O
‚
}
{O}
{O}
‚
{O}
{O}
µ
)
compounds except 4 lead to the formation of the corresponding metal selenides as confirmed by thermogravimetric
analysis and in some cases by powder X-ray diffraction studies.
Introduction
selenocarboxylate complexes to date. A major impediment
to the development of this chemistry has been the difficulty
in synthesizing the metal selenocarboxylates along with the
air- and moisture-sensitive nature of monoselenocarboxylate
anions, RC{O}Se-. However, Kato et al. have developed
synthetic routes to alkali metal selenocarboxylates and paved
way to the growth of metal selenocarboxylates.9 Our recent
work revealed that the chemistry of monoselenocarboxylate
anions need not be similar to that of the monothiocarboxy-
lates,10,11 as has been observed between the thiolates and
selenolates.12 Due to our sustained interest in the chemistry
of metal thio- and selenocarboxylates, in general, we are
prompted to explore the synthesis of [In(Se{O}Ph)4]- and
[Ga(SeC{O}Ph)4]- anions and to use them as metalloligands
to bind to various metal ions. Here, we report the syntheses
and structures of (Et3NH)[In(SeC{O}Ph)4]‚H2O and one-
dimensional coordination polymeric compounds [A(MeCN)xM-
Over the years, there has been sustained interest in the
development of the chemistry of metal thiocarboxylate
complexes, stemming not only from their interesting struc-
tural chemistry1-4 but also from the fact that many of them
can be used as single molecular precursors for the low-
temperature synthesis of metal sulfide materials, thin films,
and nanoparticles.5-8 In contrast to metal thiocarboxylate
complexes, little is known about the chemistry of metal
* To whom correspondence should be addressed. E-mail: chmjjv@
nus.edu.sg.
(1) (a) Sampanthar, J. T.; Deivaraj, T. C.; Vittal, J. J.; Dean, P. A. W. J.
Chem. Soc., Dalton Trans. 1999, 4419. (b) Burnett, T. R.; Dean, P.
A. W.; Vittal, J. J. Inorg. Chem. 1994, 72, 1127. (c) Dean, P. A. W.;
Vittal, J. J. Polyhedron 1998, 17, 1937. (d) Dean, P. A. W.; Vittal, J.
J.; Craig, D. C.; Scudder, M. L. Inorg. Chem. 1998, 37, 1661.
(2) (a) Deivaraj, T. C.; Dean, P. A. W.; Vittal, J. J. Inorg. Chem. 2000,
39, 3071. (b) Dean, P. A. W.; Vittal, J. J. Inorg. Chem. 1993, 32,
791.
(3) Dean, P. A. W.; Vittal, J. J. Inorg. Chem. 1996, 35, 3089.
(4) Devy, R.; Vittal, J. J.; Dean, P. A. W. Inorg. Chem. 1998, 37, 6939.
(5) (a) Shang, G.; Hampden-Smith, M. J.; Duesler, E. N. Chem. Commun.
1996, 1733. (b) Shang, G.; Kunze, K.; Hampden-Smith, M. J.; Duesler,
E. N. Chem. Vap. Deposition 1996, 2, 242. (c) Nyman, M. D.;
Hampden-Smith, M. J.; Duesler, E. N. Chem. Vap. Deposition 1996,
2, 171. (d) Zhang, Z. H.; Chin, W. S.; Vittal, J. J. J. Phys. Chem. B
2004, 108, 18569. (e) Lim, W. P.; Zhang, Z. H.; Low, H. Y.; Chin.
W. S. Angew. Chem., Int. Ed. 2004, 43, 5685. (f) Zhang, Z.; Lee, S.
H.; Vittal, J. J.; Chin, W. S. J. Phys. Chem. B 2006, 110, 6649.
(6) (a) Nyman, M. D.; Jenkins, K.; Hampden-Smith, M. J.; Kodas, T. T.;
Duesler, E. N.; Rheingold, A. L.; Liable-Sands, M. L. Chem. Mater.
1998, 10, 914. (b) Nyman, M. D.; Hampden-Smith, M. J.; Duesler,
E. N. Inorg. Chem. 1997, 36, 2218.
(7) (a) Deivaraj, T. C.; Park, J.-H.; Afzaal, M.; O’Brien, P.; Vittal, J. J.
Chem. Mater. 2003, 15, 2383. (b) Deivaraj, T. C.; Park, J.-H.; Afzaal,
M.; O’Brien, P.; Vittal, J. J. Chem. Commun. 2001, 2304.
(8) (a) Deivaraj, T. C.; Lin, M.; Loh, K. P.; Yeadon, M.; Vittal, J. J. J.
Mater. Chem. 2003, 13, 1149. (b) Lin, M.; Loh, K. P.; Deivaraj, T.
C.; Vittal, J. J. Chem. Commun. 2002, 1400.
(9) (a) Kato, S.; Kageyama, H.; Takagi, K.; Mizoguchi, K.; Murai, T. J.
Prakt. Chem. 1990, 332, 898. (b) Niyomura, O.; Tani, K.; Kato, S.
Heteroat. Chem. 1999, 10, 373.
(10) Zheng, L.; Huang, W.; Vittal, J. J. New J. Chem. 2002, 26, 1122.
(11) Ng, M. T.; Dean, P. A. W.; Vittal, J. J. J. Chem. Soc., Dalton Trans.
2004, 2890.
(12) Arnold, J. Prog. Inorg. Chem. 1995, 43, 353.
10.1021/ic0611286 CCC: $33.50
Published on Web 11/16/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 25, 2006 10147

Ng and Vittal
( COSe). ESI-MS (m/z) (CH2Cl2) at 50 °C: 853.1 ([In(SeC{O}Ph)4]-,
60%); 1058.5 ([In(SeC{O}Ph)4]- + 2Et3N, 60%); 391.4 ([Na(SeC-
{O}Ph)2]-, 18%); 185.5 (PhC{O}Se-, 100%). TG weight loss for
one H2O: expected, 1.9%; found, 1.8%.
(SeC{O}Ph)4] (A ) Na, K; M ) In, Ga; x ) 0, 2). Further,
we have also successfully synthesized and characterized two
heterobimetallic selenocarboxylates of Cu(I) and Ag(I),
namely, [(Ph3P)2M′In(SeC{O}Ph)4]‚CH2Cl2 (M′ ) Cu, Ag).
Recently we reported that the metal selenocarboxylates can
be used as single precursors for metal selenides.10,13 There-
fore, we have also examined the feasibility of using these
metal selenocarboxylates to prepare AMSe2 materials.
[NaGa(SeC{O}Ph)4], 2. The solvent from the sodium seleno-
carboxylate solution prepared as described above was removed to
dryness under vacuum. Deaerated H2O (30 mL) was then added to
the crude sodium monoselenocarboxylate and the insoluble pre-
cipitate was filtered off. Ga(NO3)3‚3H2O (0.70 g, 2.26 mmol)
dissolved in deaerated H2O (10 mL) was added dropwise to the
yellow filtrate via a dropping funnel to get a pale yellow precipitate.
The contents were allowed to stir for 1.5 h in ice-cold condition.
The white precipitate was filtered off, washed with plenty of water,
and then dried under vacuum and stored at 5 °C. Yield: 0.67 g
(50%). Elemental Anal. Calcd for NaGaSe4C28H20O4 (mol wt
829.02): C, 40.57; H, 2.43; Na, 2.77%. Found: C, 40.53; H, 3.00;
Na, 3.21%. 1H NMR (d6-acetone) δH: 8.00 (8H, d, J ) 7 Hz, ortho-
proton), 7.40 (8H, t, J ) 6 Hz, meta-proton), 7.51 (4H, t, J ) 6 Hz
para-proton). 13C NMR (d6-acetone) δc: for selenobenzoate
ligand: 126.12 (C2/6 or C3/5), 128.61 (C2/6 or C3/5), 131.05 (C4),
142.94 (C1), 201.50 (COSe). ESI-MS (m/z) (acetone) at 50 °C:
Experimental Section
All reactions were performed under an atmosphere of argon using
Schlenk techniques. All the starting materials were obtained
commercially and were used as received except benzoyl chloride,
which was purified by distillation under N2. Gallium metal salt Ga-
(NO3)3‚xH2O (x ≈ 3 by thermogravimetric analysis)14 was obtained
from Sigma-Aldrich. Acetonitrile was distilled from calcium hydride
under N2. Na2Se and K2Se were prepared by the literature method.15
1H, 31P{1H}, and 13C{1H} NMR spectra were recorded with a
Bruker ACF300 NMR spectrometer, with chemical shifts referenced
to residual nondeuterated solvent and external H3PO4, respectively.
Mass spectra were obtained with a Finnigan MAT LCQ (ESI)
spectrometer. All elemental analyses were performed by the
Microanalytical Laboratory in NUS. Thermogravimetric analysis
(TGA) was recorded on an SDT 2960 with simultaneous differential
thermal analysis (DTA)-TGA. Approximately 10 mg of the
precursor was decomposed under inert N2 flow (90 mL/min), and
a heating rate of 10 deg‚min-1 was used. Powder X-ray diffraction
(XRPD) patterns were recorded on a Siemens D5005 X-ray powder
diffractometer with Cu KR radiation (40 kV, 40 mA). Each sample
was measured at the rate of 0.01 deg/s from 20° to 80°.
806.9 ([Ga(SeC{O}Ph)4]-, 100%); 884.9 ([Ga(SeC{O}Ph)4]-
+
(CH3)2CO + H2O, 12%); 1635 ([(Ga(SeC{O}Ph)4)2Na]-, 45%);
185.2 (PhC{O}Se-, 100%).
[K(MeCN)2Ga(SeC{O}Ph)4], 3. To the MeCN solution (25 mL)
of K+PhC{O}Se- (3.33 mmol), Ga(NO3)3‚3H2O (0.19 g, 0.62
mmol) in MeOH (5 mL) was added to get a yellow precipitate.
The contents were then stirred for 1.5 h and heated in a water bath
to dissolve the yellow precipitate. The insoluble KNO3 was filtered
off and the yellow solution was left at 5 °C overnight to obtain
yellow needle-like crystals, which was then filtered, washed with
a small amount of cold EtOH and Et2O, and dried in vacuum. A
second crop was obtained by slowly removing the solvent under
vacuum. Total yield: 0.09 g (16%). Anal. Calcd for KGaSe4C28-
H20O4‚MeCN (mol wt 886.18): C, 40.66; H, 2.62; K, 4.41%.
Found: C, 40.07; H, 2.19; K, 4.63%. The analysis of the dried
sample matched with only one MeCN, while fresh single crystal
used for X-ray crystallography has two MeCN molecules. 1H NMR
(d6-acetone) δH: 8.01 (8H, d, J ) 6 Hz, ortho-proton), 7.40 (8H,
t, J ) 6 Hz, meta-proton), 7.51 (4H, t, J ) 7.5 Hz, para-proton).
13C NMR (d6-acetone) δc: for selenobenzoate ligand: 127.25 (C2/6
or C3/5), 128.61 (C2/6 or C3/5), 131.25 (C4), 142.97 (C1), 200.80
(COSe). ESI-MS (m/z) (acetone) at 50 °C: 807.0 ([Ga(SeC{O}Ph)4]-,
100%); 1029.0 ([KGa(SeC{O}Ph)4 + PhCOSe-], 6%); 884.9
([Ga(SeC{O}Ph)4]- + (CH3)2CO + H2O, 4%); 185.3 (PhC{O}Se-,
40%). TG weight loss for one MeCN: expected, 4.6%; found, 2.7%.
[NaIn(SeC{O}Ph)4], 4. Compound 4 was synthesized via a
synthetic strategy similar to that used for 2 except that InCl3 was
used instead of Ga(NO3)3‚3H2O. Yield: 1.55 g (78%). Elemental
Anal: Calcd. for NaInSe4C28H20O4 (mol wt 874.11): C, 38.47; H,
Sodium Selenocarboxylate, Na+PhC{O}Se-.9a Benzoyl chlo-
ride (1.05 mL, 9.05 mmol) was added to a suspension of Na2Se
(1.47 g, 11.77 mmol) in MeCN at 0 °C under an argon atmosphere,
and the color of the mixture rapidly changed to yellow. After the
mixture was stirred for 1 h, NaCl and unreacted Na2Se were filtered
off using a G4 Umkehr filter. The solution of Na+RC{O}Se- was
used in the following syntheses of compounds 2 and 4.
Potassium Selenocarboxylate, K+PhC{O}Se-.9b The reaction
was carried out similarly to that for sodium selenocarboxylate, but
K2Se was used instead of Na2Se. The solution of K+RC{O}Se-
was used in the following syntheses of compounds 3 and 5.
(Et3NH)[In(SeC{O}Ph)4]‚H2O, 1. To a solution of [NaIn(SeC-
{O}Ph)4] (0.18 g, 0.20 mmol) (refer to the synthesis of 4) in acetone
(4 mL), Et3NHCl (0.03 g, 0.20 mmol) dissolved in MeCN (4 mL)
was added dropwise at ambient condition. The solution was allowed
to stir for 0.5 h and the solvents were removed completely under
vacuum. The product was then extracted in CH2Cl2 (5 mL) and
layered with hexane. A crystalline product was obtained by keeping
the solution at 5 °C overnight. The yellow crystals were filtered
off, washed with MeOH and Et2O, and then dried under vacuum
and stored at 5 °C for further use. Yield: 0.15 g (78%). Elemental
Anal. Calcd for InSe4O4C34H36N‚H2O (mol wt. 971.34): C, 42.04;
H, 3.94; N, 1.44%. Found: C, 41.82; H, 3.95; N, 1.47%. 1H NMR
(CDCl3) δH: 8.01 (8H, d, J ) 6 Hz, ortho-proton), 7.31 (8H, t, J
) 7.5 Hz, meta-proton), 7.45 (4H, t, J ) 7.5 Hz , para-proton),
3.33 (6H, q, J ) 8 Hz, CH2CH3), 1.31 (9H, t, J ) 7.5 Hz, CH2CH3).
13C NMR (CDCl3) δc: for selenobenzoate ligand: 126.92 (C2/6 or
1
2.31; Na, 2.63%. Found C, 38.39; H, 2.17; Na, 2.58%. H NMR
(d6-acetone) δH: 8.02 (8H, d, J ) 6 Hz, ortho-proton), 7.40 (8H,
t, J ) 6 Hz, meta-proton), 7.51 (4H, t, J ) 6 Hz para-proton). 13
C
NMR (d6-acetone) δc: For selenobenzoate ligand: 126.12 (C2/6 or
3/5), 128.41 (C2/6 or C3/5), 130.75 (C4), 141.94 (C1), 201.80 (COSe).
C
ESI-MS (m/z)(acetone) at 50 °C: 898.5, ([NaIn(SeC{O}Ph)4] +
Na+, 100%); 852.8, ([In(SeC{O}Ph)4]-, 60%); 185.3, (PhC{O}Se-,
100%).
[K(MeCN)2In(SeC{O}Ph)4], 5. Compound 5 was synthesized
using a procedure similar to that for 3 except that InCl3 was used
instead of Ga(NO3)3‚3H2O. Unlike Ga(NO3)3‚3H2O, InCl3 powder
was added directly into PhCOSe- solution. Yield: 70%. Anal. Calcd
for the desolvated product, KInSe4C28H20O4 (mol wt 890.22): C,
C
3/5), 128.31 (C2/6 or C3/5), 130.05 (C4), 140.94 (C1), 201.15
(13) Ng, M. T.; Boothroyd, C.; Vittal, J. J. Chem. Commun. 2005, 3820.
(14) Deivraj, T. C.; Lye, W. H.; Vittal, J. J. Inorg. Chem. 2002, 41, 3755.
(15) Thompson, D. P.; Boudjouk, P. J. Org. Chem. 1988, 53, 2109.
10148 Inorganic Chemistry, Vol. 45, No. 25, 2006

Molecular Precursors for Ternary Selenides
Table 1. Crystallographic Data and Refinement Parameters for 1, 3, 5, 6, and 7
1a
3
5
6
7
formula
fw
C34H38InNO5Se4
971.34
C32H26N2GaKO4Se4
927.21
C32H26N2InKO4Se4
972.31
C65H52CuInO4P2Se4Cl2
1524.11
C65H52AgInO4P2Se4Cl2
1568.44
T, K
223
223
233
223
223
λ, Å
0.710 73
orthorhombic
P212121
13.0491(5)
13.0760(4)
21.7114(7)
90
90
90
3704.6(2)
4
1.742
0.710 73
monoclinic
P21/n
12.3468(5)
13.8322(6)
20.7219(8)
90
91.535(2)
90
3537.7(3)
4
0.710 73
monoclinic
P21/n
12.4406(7)
13.8078(7)
20.7791(1)
90
91.647(2)
90
3567.9(3)
4
0.710 73
triclinic
P1h
0.710 73
triclinic
P1h
crystal system
space group
a, Å
12.6678(9)
13.9765(10)
18.8875(13)
90.999(2)
101.415(2)
110.784(2)
3050.5(4)
2
1.659
3.300
R1 ) 0.0380,
wR2 ) 0.0694
12.7983(6)
14.0942(7)
18.7509(9)
91.009(1)
100.373(1)
111.089(1)
3091.7(3)
2
1.685
3.229
R1 ) 0.0318,
wR2 ) 0.0708
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
F, g cm-3
µ, mm-1
final R indicesb
(I > 2σ(I))
1.741
5.048
R1 ) 0.0346,
wR2 ) 0.0724
1.810
4.896
R1 ) 0.0457,
wR2 ) 0.0776
4.607
R1 ) 0.0362,
wR2 ) 0.0855
a Flack parameter, 0.020(9). b R1 ) (∑||Fo - |Fc||)/∑|Fo|; wR2 ) [∑w(Fo - Fc )/∑wFo ]1/2
.
2
2
4
37.78; H, 2.26; K, 4.39%. Found: C, 37.80; H, 2.18; K, 4.39%.
The dried sample contains no MeCN solvent molecule, while fresh
single crystal used for X-ray crystallography has two MeCN
molecules. 1H NMR (d6-acetone) δH: 8.02 (8H, d, J ) 6 Hz, ortho-
proton), 7.41 (8H, t, J ) 7.5 Hz, meta-proton), 7.52 (4H, t, J )
7.5 Hz para-proton). 13C NMR (d6-acetone) δc: for selenobenzoate
ligand: 127.10 (C2/6 or C3/5), 128.48 (C2/6 or C3/5), 131.05 (C4),
142.90 (C1), 201.50 (COSe). ESI-MS (m/z) (acetone) at 50 °C:
ESI-MS (m/z) (CH2Cl2) at 50 °C: 631.0 ([(PPh3)2Ag]+, 100%);
852.8 ([In(SeC{O}Ph)4]-, 100%); 185.3 (PhC{O}Se-, 100%). TG
weight loss for one CH2Cl2: expected, 5.4%; found, 2.3%. Single
crystals of [(PPh3)2AgIn(SeC{O}Ph)4] were obtained by layering
Et2O over CH2Cl2 solution of 7 at 5 °C overnight.
X-ray Crystallography. The diffraction experiments were
carried out on a Bruker SMATR CCD diffractormeter with a Mo
KR sealed tube. The program SMART17 was used for collecting
frames of data, indexing reflection, and determining lattice param-
eters; SAINT17 was used for integration of the intensity of
reflections and scaling. SADABS18 was used for absorption
correction, and SHELXTL19 was used for space group and structure
determination and least refinement on F2. Selected crystallographic
data of experimental details are compiled in Table 1.
852.8 ([In(SeC{O}Ph)4]-, 100%); 930.0 ([In(SeC{O}Ph)4]-
+
(CH3)2CO + H2O, 2%); 1074.7 ([KIn(SeC{O}Ph)4 + PhCOSe-],
15%); 1742.0 ([(In(SeC{O}Ph)4)2K]-, 80%); 185.2 (PhC{O}Se-,
17%).
[(Ph3P)2CuIn(SeC{O}Ph)4]‚CH2Cl2, 6. Compound 6 was syn-
thesized using a procedure similar to that for 1 except that [(Ph3P)2-
Cu(NO3)]16 was used instead of Et3NHCl. Yield: 78%. Elemental
Anal. Calcd for CuInSe4P2C64H50O4‚CH2Cl2 (mol wt 1524.18): C,
51.22; H, 3.44; P, 4.06%. Found: C, 51.56; H, 3.18; P, 4.30%. 1H
NMR (CDCl3) δH: 7.88 (8H, d, J ) 6 Hz, ortho-proton), 7.15 (8H,
t, J ) 7.5 Hz, meta-proton), 7.25-7.45 (34H, m, para-proton and
PPh3), 5.32 (2H, CH2Cl2). 13C NMR (CDCl3) δc: for selenobenzoate
ligand: 126.12 (C2/6 or C3/5), 128.11 (C2/6 or C3/5), 130.75 (C4),
141.94 (C1), 202.50 (COSe); for PPh3: 128.15 (C3), 129.30 (C4),
133.14 (C1), 133.95 (C2). 31P NMR (CDCl3) δp: -1.31. ESI-MS
(m/z) (CH2Cl2) at 50 °C: 848.7 ([(PPh3)3Cu]+, 100%); 852.9
([In(SeC{O}Ph)4]-, 100%); 185.3 (PhC{O}Se-, 85%); 703.7 (In-
(SeC{O}Ph)3 + Cl-, 18%). TG weight loss for one CH2Cl2:
expected, 5.5%; found, 3.2%. Single crystals of 6 were obtained
by layering Et2O over the CH2Cl2 solution of 6 and stored at 5 °C
for overnight.
Results and Discussion
Synthesis. The compounds [NaGa(SeC{O}Ph)4] (2),
[K(MeCN)2Ga(SeC{O}Ph)4] (3), [NaIn(SeC{O}Ph)4] (4),
and [K(MeCN)2In(SeC{O}Ph)4] (5) were prepared by simple
metathesis between the metal salts and appropriate amounts
of the corresponding alkali metal selenocarboxylates in either
H2O or MeCN solvent. (Et3NH)[In(SeC{O}Ph)4]‚H2O (1),
[(Ph3P)2CuIn(SeC{O}Ph)4]‚CH2Cl2 (6), and [(Ph3P)2AgIn-
(SeC{O}Ph)4]‚CH2Cl2 (7) were prepared by the metathesis
between the ionic salts Et3NHCl, [(Ph3P)2Cu(NO3)] or
[(Ph3P)2Ag(NO3)], and 4 in either CH2Cl2/(Me)2CO or CH2-
Cl2/MeCN solvents.
Compounds 2 and 4 could not be isolated if the reaction
was conducted in MeCN alone. Similarly, complexes 1, 6,
and 7 could not be isolated from the in situ reaction, unlike
the corresponding metal thiocarboxylates, which were iso-
lated from in situ complexation.7,8 Unfortunately, the gallium
analogues of 1, 6, and 7 could not be isolated from the
[(Ph3P)2AgIn(SeC{O}Ph)4]‚CH2Cl2, 7. To an acetone (5 mL)
solution of [NaIn(SeC{O}Ph)4] (0.64 g, 0.73 mmol) a CH2Cl2 (5
mL) solution of [(PPh3)2Ag(NO3)]16 (0.51 g, 0.73 mmol) was added
dropwise. A brownish gray precipitate was formed immediately
upon stirring. The solution was allowed to stir for 0.5 h, and the
precipitate was filtered off and washed with MeOH, H2O, and Et2O.
The product was then dried under vacuum and stored at 5 °C.
Yield: 0.71 g (65%). Elemental Anal. Calcd for AgInSe4P2C64H50-
O4‚CH2Cl2 (mol wt 1568.51): C, 49.77; H, 3.34; P, 3.95%. Found
C, 50.28; H, 3.09; P, 3.89%. 1H NMR (CDCl3) δH: 7.73 (8H, d, J
) 6 Hz, ortho-proton), 7.11 (8H, t, J ) 7.5 Hz, meta-proton), 7.24-
7.42 (34H, m, para-proton and PPh3). 13C NMR (CDCl3) δc: for
selenobenzoate ligand: 127.12 (C2/6 or C3/5), 128.61 (C2/6 or C3/5),
131.05 (C4), 142.94 (C1), 201.50 (COSe); for PPh3: 128.15 (C3),
129.30 (C4), 133.14 (C1), 133.95 (C2). 31P NMR (CDCl3) δp: 7.35.
(16) (a) Kubas, G. J. Inorg. Synth. 1970, 19, 93. (b) Bowmaker, G. A.;
Effendy, A. H. J.; Healy, P. C.; Skelton, B. W.; White, A. H. J. Chem.
Soc., Dalton Trans. 1993, 1387.
(17) SMART & SAINT Software Reference Manuals, version 5.0; Bruker
Analytical X-ray Systems, Inc.: Madison, WI, 2000.
(18) Sheldrick, G. M. SADABS a software for empirical absorption
correction, version 2.03; University of Go¨ttingen: Go¨ttingen, Ger-
many, 2000.
(19) SHELTX Reference Manual, version 6.13; Bruker Analytical X-ray
Systems, Inc.: Madison, WI, 2000.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10149

Ng and Vittal
Figure 1. Ball-and-stick diagram of 1.
Figure 2. Perspective view showing the coordination environment around
the metal centers in 5.
Table 2. Selected Bond Lengths (Å) and Angles (deg) of 1
Bond Distances
Table 3. Selected Bond Distances (Å) and Angles (deg) in 3 and 5
In(1)-Se(1)
In(1)-Se(2)
In(1)-Se(3)
In(1)-Se(4)
Se(1)-C(1)
Se(2)-C(2)
Se(3)-C(3)
Se(4)-C(4)
2.5615(7)
2.5790(7)
2.5784(7)
2.5659(7)
1.861(6)
1.902(6)
1.918(5)
1.914(5)
3 (M ) Ga)
5 (M ) In)
Bond Distances
M-Se(1)
2.393(1)
2.560(1)
M-Se(2)
2.419(1)
2.418(1)
2.398(1)
2.703(3)
2.741(3)
2.700(3)
2.841(4)
2.851(5)
2.606(1)
2.610(1)
2.581(1)
2.696(4)
2.797(4)
2.726(4)
2.852(6)
2.844(6)
M-Se(3)
M-Se(4)
O(1)-K(1)
O(2)-K(1)
O(4)-K(1)a
K(1)-N(1)
K(1)-N(2)
Bond Angles
Se(1)-In(1)-Se(2)
Se(1)-In(1)-Se(3)
Se(1)-In(1)-Se(4)
Se(2)-In(1)-Se(3)
Se(2)-In(1)-Se(4)
Se(3)-In(1)-Se(4)
106.74(3)
104.50(3)
116.64(3)
110.04(2)
104.63(2)
114.08(3)
Bond Angles
Se(1)-M-Se(2)
Se(1)-M-Se(3)
Se(1)-M-Se(4)
Se(3)-M-Se(2)
Se(4)-M-Se(2)
Se(4)-M-Se(3)
O-K-O
110.30(2)
106.45(2)
123.47(2)
103.82(2)
105.20(2)
105.92(2)
69.84(8)-88.05(9)
70.10(8)-131.10(8)
60.92(2)-114.23(2)
61.27(6)-148.24(7)
74.86(1)-143.37(9)
111.8(1)
110.93(3)
105.34(2)
125.65(2)
102.45(2)
105.12(2)
104.93(2)
67.9(1)-87.7(1)
68.9(1)-133.8(1)
64.71(2)-142.21(4)
62.17(8)-150.4(1)
74.5(1)-142.5(1)
109.2(2)
reaction solution under these conditions due to rapid
decomposition of the products even though the solution was
kept at 5 °C for recrystallization.
Compounds 2-5 are insoluble in CH2Cl2 or CHCl3 but
soluble in Me2CO and warm MeCN, and compounds 1, 6,
and 7 are very soluble in CH2Cl2 and CHCl3. The compounds
are stable for months if stored at 5 °C. However, unlike the
corresponding metal thiocarboxylates,14 compounds 2-5
decomposed slowly upon standing in ambient condition for
long time. The structural characterization of these compounds
mainly depends on X-ray crystallography, because the usual
spectroscopic techniques are not very informative.
Structural Descriptions. Compounds 3 and 5 are one-
dimensional coordination polymers in which the [M(SeC-
{O}Ph)4]- ions (M ) Ga, In) act as a multidentate ligand
bound to the K cation. In addition, the structures of 3 and 5
are isotypical. On the other hand, 1 is a discrete ionic
complex. Compounds 6 and 7 are bimetallic dimers with an
A(µ-Se)2In core (A ) Cu, Ag) and are isostructural with
each other and to the corresponding silver thiocarboxylate
structure.7 Detailed structural descriptions are given in the
following sections.
Structure of (Et3NH)[In(SeC{O}Ph)4]‚H2O, 1. 1 con-
tains a discrete unit of [In(SeC{O}Ph)4]- anions and hydrated
cation as illustrated in Figure 1. Selected bond distances and
angles of compound 1 are listed in Table 2. As shown in
Figure 1, the indium metal center in 1 is covalently bonded
to four selenocarboxylates through selenium atoms. Further,
the Se-In-Se angles (104.50(3)-116.64(3)°) indicate dis-
tortions from the ideal tetrahedral geometry. In 1, the
N-K-Se
Se-K-Se
O-K-Se
O-K-N
N-K-N
a Symmetry transformation used to general equivalent atoms: -x + 3/2,
y + 1/2, -z + 1/2.
triethylammonium cation is hydrogen bonded to the water
molecule through the amine hydrogen atom. Overall, the
structural feature of 1 resembles that of the corresponding
thiocarboxylate.8
Structures of [K(MeCN)2{M(SeC{O}Ph)4}] (M ) Ga
(3), In(5)). As mentioned above, both 3 and 5 are isostruc-
tural. A portion of the polymeric structures of these two
compounds showing the details of the geometries around the
metal ions and PhC{O}Se- ligands is illustrated in Figure 2
for 5. Selected bond lengths and angles are displayed in Table
3. In these two compounds, four of the selenobenzoate
ligands are bonded to the metal ions through selenium atoms.
The distances between gallium and selenium in 3 are nearly
identical, which range from 2.393(1) to 2.419(1) Å. Unlike
3, the In-Se distances in 5 are in a wider range, 2.560(1)-
2.610(1) Å. In these structures, the M‚‚‚O distances are less
than the sum of their van der Waals radii (3.40 Å), suggesting
the presence of weak interactions in these two complexes.20
(20) Bondi, A. J. Phys. Chem. 1964, 68, 441.
10150 Inorganic Chemistry, Vol. 45, No. 25, 2006

Molecular Precursors for Ternary Selenides
Figure 3. Segment of one-dimensional coordination of 5. The hydrogen atoms are omitted for clarity. The color codes are as follows: blue sphere, K; red,
O; orange, Se; blue open circle, N; yellow circle, In.
In the solid state 3 and 5 form one-dimensional (1D)
polymeric structures with alternating repeating units of
[K(MeCN)2]+ and [M(SeC{O}Ph)4]-. A portion of these
coordination polymers is illustrated in Figure 3, and each
polymeric strand is arranged parallel to the b-axis. One of
the [M(SeC{O}Ph)4]- units binds to potassium as a tridentate
ligand through two carboxyl oxygen atoms, namely O(1) and
O(2), and a selenium atom (Se(4)). Further, another
[M(SeC{O}Ph)4]- unit binds through one oxygen atom, O(4),
and two selenium atoms, Se(1) and Se(3). In addition, two
acetonitrile molecules coordinate to the potassium ion. The
K-Se distances in 3 (3.750(1)-3.824(1) Å) and 5 (3.668-
(2)-3.857(2) Å) are larger than the reported values found
in potassium 2-methoxybenzenecarboselenoate (3.309(1)-
Figure 4. Perspective view of 6. Hydrogen atoms have been removed for
clarity.
3.625(2) Å)21 but shorter than the sum of van der Waals radii
(4.70 Å).20 If the weak interactions between K and Se are
taken into account, the geometry at the potassium ion is
considered as eight-coordinated highly distorted hexagonal
bipyramidal geometry with a Se3O3N2 donor set. Compound
5 is found to be isomorphous to [K(MeCN)2In(SC{O}Ph)4],14
but the coordination number and geometry at K are slightly
different.
Structures of [(Ph3P)2M′In(SeC{O}Ph)4]‚CH2Cl2, (M′
) Cu (6), Ag (7)). A perspective view of 6 and 7 is shown
in Figure 4, and selected bond distances and angles are given
in Table 4. In the asymmetric unit containing heterobimetallic
compounds, a CH2Cl2 molecule is present in the crystal lattice
similar to the thiocarboxylate analogue of Ag(I) compound.7
As illustrated in Figure 4, a [In(SeC{O}Ph)4]- anion is
bonded to M′(PPh3)2+ cation through two bridging SeC{O}Ph-
ligands through Se atom forming a M′InSe2 ring (M′ ) Cu,
Ag). Apart from four In-Se bonds, weak interactions were
also observed between the indium and two carbonyl oxygens
in 6 (In(1)‚‚‚O(3), 2.883 Å; In(1)‚‚‚O(4), 2.976 Å) and in 7
(In(1)‚‚‚O(3), 2.897 Å; In(1)‚‚‚O(4), 2.958 Å). Hence, the
geometry at the indium metal center is six-coordinated
distorted octahedron and the geometry at the group 11 metal
Table 4. Selected Bond Lengths (Å) and Angles (deg) of 6 and 7
6 (M′ ) Cu)
7 (M′ ) Ag)
Bond Distances
2.636(1)
2.635(1)
2.554(1)
2.551(1)
2.283(1)
2.278(1)
2.567(1)
2.567(1)
In(1)-Se(1)
In(1)-Se(2)
In(1)-Se(3)
In(1)-Se(4)
M′-P(1)
2.637(1)
2.640(1)
2.555(1)
2.554(1)
2.467(1)
2.461(1)
2.778(1)
2.767(1)
M′-P(2)
M′-Se(1)
M′-Se(2)
Bond Angles
93.36(2)
Se(2)-In(1)-Se(1)
Se(3)-In(1)-Se(1)
Se(4)-In(1)-Se(1)
Se(3)-In(1)-Se(2)
Se(4)-In(1)-Se(2)
Se(4)-In(1)-Se(3)
P(2)-M′-P(1)
Se(2)-M′-Se(1)
M′-Se(1)-In(1)
M′-Se(2)-In(1)
99.30(1)
111.47(2)
101.25(2)
103.87(1)
109.55(1)
127.95(2)
122.98(3)
92.99(1)
83.76(1)
83.92(1)
112.84(2)
103.63(2)
107.12(2)
110.48(2)
124.90(2)
121.77(4)
96.67(2)
84.96(2)
84.98(2)
ion is distorted tetrahedron with P2M′Se2 core (M′ ) Cu,
Ag). The M′-P distances are normal and do not warrant
any additional comment. It may be noted that the benzoyl
group at the bridging selenium atoms have “anti” configu-
ration and the Se-C bonds are tilting away from the M′-
(21) Niyomura, O.; Kato, S.; Kanda, T. Inorg. Chem. 1999, 38, 507.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10151

Ng and Vittal
Figure 5. XRPD patterns of 2 and 4.
Figure 6. Overlay of thermogravimetric curves of 1-7.
(PPh3)2. The nonbonding Cu‚‚‚In distance, 3.52 Å, is,
therefore, longer compared to distances in the reported
compounds such as (Ph3P)2Cu(µ-SEt)2In(SEt)2 (3.34 Å),
(Ph3P)Cu(µ-SeEt)2In(SeEt)2 (3.32 Å), and (Ph3P)2Cu(µ-
(S(iso-Bu))2In(S(iso-Bu))2 (3.24 Å).22
selenide materials was investigated by thermogravimetry and
pyrolysis experiments. The TGA curves are presented in
Figure 6, and the results are summarized in Table 5.
It is unusual that 6 and 7 can retain CH2Cl2 up to 145 and
135 °C, respectively, and similar behavior was also observed
in the corresponding thiocarboxylates.7a To our surprise, no
distinct intra- or intermolecular interactions that one might
expect for retaining the CH2Cl2 molecule were found in the
crystal lattices of these compounds, and we are currently
investigating this unusual retention of CH2Cl2 solvent well
above its boiling point. All the compounds started decom-
posing in the temperature range 144-192 °C and completed
400-450 °C, except 6 and 7, where the decomposition
process ended at a relatively low temperature. Overall, the
decomposition profiles of these metal selenocarboxylates are
similar to those of the corresponding metal thiocarboxy-
lates.7,8,14 As shown in Figure 6, no distinct plateau was
observed after major weight loss in 2-5 until at least 600
°C. This suggested that the AMSe2 (A ) Na, K; M ) In,
Ga) could be unstable at high temperature and undergo
decomposition which led to the decrease of the residual
weight. In fact, we previously observed that GaCuS2 is
unstable at high temperature:8a when we tried to deposit this
material at temperatures higher than 400 °C by MOCVD, it
decomposed to a mixture of products. Thus, this illustrated
the poor thermal stability of some ternary metal sulfides.
The pyrolysis products of 2-5 were stored under dry argon
atmosphere to prevent any decomposition, as it has been
stated that NaInSe2 is unstable at ambient conditions and
will react with moisture to form H2Se and acid.23 The
elemental stochiometry of the decomposed products char-
acterized by EDX (energy dispersive X-ray spectroscopy)
are in the expected range of 1:1:2 (Na/K:Ga/In:Se) for
Overall, 6 and 7 are isostructural and isomorphous to each
other. However, 7 is isostructural with the corresponding
thiocarboxylate analogue, but 6 is not. This could be due to
the large size of the selenium atom that is able to release
the steric crowd around Cu(I), thereby accommodating one
more PPh3 unlike the sulfur analogue.7a This is supported
by the fact that the larger size of Ag atom enables (Ph3P)2-
Ag to bind to the [In(EC{O}Ph)4]- (E ) S, Se) units without
affecting the overall molecular strength or crystal packing.7b
A close examination of the molecular structure of 6 in Figure
4 may reveal the presence of an approximate noncrystallo-
graphic 2-fold symmetry along the M′-In bond. Interest-
ingly, this is not reflected in the crystal structure symmetry.
The presence of alkali metal inflicts a strong distortion at
the In(III) metal centers through the selenocarboxylate
ligands. However, the bond parameters at the potassium
cations in 3 and 5 are similar, remain undisturbed by
changing from thiobenzoate to selenobenzoate ligand, and
have little effect on the overall polymeric structure of this
type of compound. Unfortunately, single crystals of 2 and 4
suitable for X-ray crystallography were not obtained, but the
XRPD patterns of 2 and 4 are similar (Figure 5), indicating
that they are isomorphous and isostructural, but different
from the generated XRPD patterns of [NaIn(SCOPh)4]14 and
5. Hence choice of solvent has a strong effect on the overall
crystal structure of these alkali metal incorporated group III
metal thio- or selenocarboxylates.
Thermogravimetry and Pyrolysis. The usefulness of
compounds 1-7 as single-source precursors for metal
(22) Hirpo, W.; Dhingra, S.; Sutorik, A. C.; Kanatzidis, M. G. J. Am. Chem.
Soc. 1993, 115, 1597.
(23) Macintyre, J. E. Dictionary of Inorganic Compounds, 1st ed.;
London: New York, 1992.
10152 Inorganic Chemistry, Vol. 45, No. 25, 2006

Molecular Precursors for Ternary Selenides
Table 5. Pyrolysis and TGA Results for 1-7
compd
temp range (°C)
residual wt obsd (calcd) (%)
residual wt from pyrolysisa (%)
product of decomposition (JCPDS No.)
desolvated 1
1
50-139
139-409
149-409
150-396
192-446
180-425
RT-145
176-356
RT-135
178-361
98.7 (98.2)
25.0 (24.5)
27.1
27.3
26.8
37.3
30.0
In2Se3 (40-1407)
b
2
3
4
5
6
23.0-28.0 (30.2)
26.7-32.3 (30.1)
32.7-38.2 (33.8)
26.4-36.0 (35.0)
96.8 (94.5)
23.9 (22.1)
97.7 (94.6)
26.5 (24.3)
NaGaSe2
KGaSe2 (isostructural to KGaTe2 (01-070-5286)
unknown
KInSe2 (01-070-6110).
desolvated 6
CuInSe2 (40-1487)
desolvated 7
22.3
26.6
7
AgInSe2 (035-01099)
a 4 was heated at 500 °C for 2 h; 1, 2, and 5 were heated at 450 °C for 1 h; 3 was heated at 350 °C for 30 min; 6 and 7 were heated at 300 °C for 30
min. b Based on the EDX analyses.
Figure 8. XRPD patterns of decomposed products of compounds 1, 6,
and 7.
Figure 7. XRPD patterns of pyrolyzed products of 3 and 5 along with
the reported XRPD pattern of KInSe2.
decomposed products of 1, 6, and 7 confirmed the formation
compounds 2, 3, and 5.24 Further, the XRPD pattern of the
of the corresponding ternary metal selenides as shown in
decomposed product of 5 is matched with the known
Figure 8. The sharp peaks in the XRPD patterns stem from
monoclinic KInSe2 (JCPDS No. 01-070-6110) as shown in
the strong crystalline nature of the metal selenides. Further,
Figure 7. The XRPD pattern for KGaSe2 is not available to
no other peaks are present at high temperatures, showing
date; however, the XRPD pattern of the product of pyrolysis
of 3 closely resembles that of KGaTe2 (JCPDS No. 01-070-
the feasibility of using these metal selenocarboxylates as
single source precursors to synthesize the corresponding
5286) and hence it may be concluded that KGaSe2 might be
ternary metal selenides in either the form of thin films or
isostructural with the monoclinic KGaTe2.24 Although EDX
nanoparticles. This is supported by the fact that 7 decom-
shows the correct stoichiometry for the decomposed product
of 2 to be 1:1:2 (Na:Ga:Se). The XRPD pattern of the
pyrolyzed product does not match or resemble with any
known phase of sodium gallium selenide including
Na2Ga2Se3.24 Hence, based on the EDX analysis, we pro-
posed that the XRPD pattern could be due to a new phase
posed in the presence of dodecanethiol and oleylamine
ligands when a new phase AgInSe2 nanorod, which is
isostructural to AgInS2, can be obtained.25
Summary
NaGaSe2. Both the EDX and XRPD analyses of the
pyrolyzed product of 4 do not match with NaInSe2. Hence
We have shown that [M(SeC{O}Ph)4]- can be used as
metalloligand to bind to alkali metal ions and [In(SeC-
compound 4 might adopt a different decomposition pathway
{O}Ph)4]- can be used for Cu(I) and Ag(I). The solid-state
and the expected NaInSe2 is not formed.
structures of 6 and 7 are isotypical and are very similar to
that of [(Ph3P)2AgIn(SC{O}Ph)4]‚CH2Cl2.7a The K(I) salts
In contrast, a sharp plateau was observed in the TGA of
of [M(SeC{O}Ph)4]- (M ) Ga, In) have 1D coordination
1, 6, and 7. The observed residual weights are in fair
agreement with the calculated values. XRPD patterns of the
(25) Ng, M. T.; Boothroyd, C.; Vittal, J. J. J. Am. Chem. Soc. 2006, 128,
(24) See Supporting Information.
7118.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10153

Ng and Vittal
polymeric structures in the solid state. Based on the TGA,
pyrolysis, EDX, and XRPD experiments, 2, 3, and 5
thermally decomposed to the corresponding AMSe2. If these
compounds are subjected to one-pot colloidal synthesis, one
might be able to isolate stable AMSe2 nanoparticles by the
use of surfactants to cap and stabilize them.25,26 On the other
hand, In2Se3, CuInSe2, and AgInSe2 can be obtained respec-
tively from 1, 6, and 7. Hence, these precursors may provide
an alternative route to synthesizing the corresponding thin
films, which are promising photovoltaic materials.
Acknowledgment. We would like to thank the NUS for
their generous financial support through Grant R-143-000-
283-112.
Supporting Information Available: Crystallographic data in
CIF format for 1, 3, and 5-7. EDX spectra of the pyrolysis products
of 2-5, and table containing the elemental analysis of the pyrolyzed
products of 2-5. This material is available free of charge via the
Internet at http://pubs.acs.org.
(26) (a) Chen, X.; Xu, H.; Xu, N.; Zhao, F.; Lin, W.; Lin, G.; Fu, Y.;
Huang, Z.; Wang, H.; Wu, M. Inorg. Chem. 2003, 42, 3100. (b) Zhao,
Y.; Zhang, Y.; Zhu, H.; Hadjipanayis, G. C.; Xiao, J. Q. J. Am. Chem.
Soc. 2004, 126, 6874. (c) Li, Y.; Li, X.; Yang, C.; Li, Y. J. Phys.
Chem. B 2004, 108, 16002.
IC0611286
10154 Inorganic Chemistry, Vol. 45, No. 25, 2006