3-Dimethylaminopropyl chalcogenolate complexes of palladium(II): Syntheses and characterization, including the crystal structures of [Pd(OAc)(ECH 2CH2CH2NMe2)]2· H2O (E = S, Se) and [PdCl(TeCH2CH2CH 2NMe2)]2

Article abstract of DOI:10.1016/j.ica.2005.09.019

The reactions of the sodium salts of 3-dimethylamino-1- propylchalcogenolates, prepared by sodium borohydride reduction of (Me ₂NCH₂CH₂CH₂E)₂ in methanol, with Na₂PdCl₄ yielded homoleptic [Pd(ECH ₂CH₂CH₂NMe₂)₂] ₆ (1) (E = S (1a); Se (1b); Te (1c)). When treated with [Pd(OAc) ₂]₃ or Na₂PdCl₄, compounds 1 readily gave binuclear redistribution products [PdX(ECH₂CH ₂CH₂NMe₂)]₂ where X = OAc (2) (E = S (2a); Se (2b); or Cl (3)) (E = S (3a); Se (3b); Te (3c)), respectively. The terminal acetate/chloride ligands in 2b/3b can be substituted by other ionic ligands like PhSe^-. The complexes were characterized by elemental analysis, UV-Vis, IR and NMR spectroscopy. The structures of 2a, 2b and 3c were established by X-ray crystallography. Each molecule has a dimeric structure in which there are two chalcogenolate bridges from the chelating 3-dimethylamino-1-propylchalcogenolate ligands. On pyrolysis, compound 2b affords Pd₁₇Se₁₅.

Full text of DOI:10.1016/j.ica.2005.09.019

Inorganica Chimica Acta 359 (2006) 1449–1457
www.elsevier.com/locate/ica
3-Dimethylaminopropyl chalcogenolate complexes of
palladium(II): Syntheses and characterization, including the crystal
structures of [Pd(OAc)(ECH2CH2CH2NMe2)]2 Æ H2O (E = S, Se)
and [PdCl(TeCH2CH2CH2NMe2)]2
a
a,
b
c
c
Sandip Dey , Vimal K. Jain *, Babu Varghese , Thilo Schurr , Mark Niemeyer ,
c
d
Wolfgang Kaim , Ray J. Butcher
a
Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
b
RSIC, Indian Institute of Technology, Chennai 600 036, India
Institut fuer Anorganische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
c
d
Department of Chemistry, Howard University, Washington, DC 20059, USA
Received 31 August 2005; accepted 16 September 2005
Available online 26 October 2005
Abstract
The reactions of the sodium salts of 3-dimethylamino-1-propylchalcogenolates, prepared by sodium borohydride reduction of
(Me2NCH2CH2CH2E)2 in methanol, with Na2PdCl4 yielded homoleptic [Pd(ECH2CH2CH2NMe2)2]6 (1) (E = S (1a); Se (1b); Te
(1c)). When treated with [Pd(OAc)2]3 or Na2PdCl4, compounds
1
readily gave binuclear redistribution products
[PdX(ECH2CH2CH2NMe2)]2 where X = OAc (2) (E = S (2a); Se (2b); or Cl (3)) (E = S (3a); Se (3b); Te (3c)), respectively. The terminal
acetate/chloride ligands in 2b/3b can be substituted by other ionic ligands like PhSeꢀ. The complexes were characterized by elemental
analysis, UV–Vis, IR and NMR spectroscopy. The structures of 2a, 2b and 3c were established by X-ray crystallography. Each molecule
has a dimeric structure in which there are two chalcogenolate bridges from the chelating 3-dimethylamino-1-propylchalcogenolate
ligands. On pyrolysis, compound 2b affords Pd17Se15.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: 3-Dimethylaminopropyl chalcogenolate; Acetate; Palladium(II); Crystal structure; NMR
1. Introduction
olates in particular constitute an interesting family of
ligands which have not only shown versatile coordination
chemistry [1–6], but also exhibited high catalytic activities
[6,7]. The structures of their complexes are greatly influ-
enced by the nature of the metal ion, the number of inter-
vening atoms separating the N and S centers, and the
substituents on the N atom. Internal functionalization of
chalcogenolate ligands assists in suppressing polymeriza-
tion of the metal complexes and consequently makes them
promising candidates as precursor molecules for the syn-
thesis of metal chalcogenides.
Hemilabile ligands have attracted considerable attention
for more than two decades due to their potential applica-
tions in catalysis. These ligands contain at least two differ-
ent types of donor atoms, one of which binds the metal
center firmly, while the other donor site is substitutionally
labile. Over a period, a wide variety of hemilabile ligands
have been designed and synthesized. Among them, inter-
nally functionalized thiolates in general and aminoalkylthi-
The palladium and platinum complexes with thiolates in
which S and N are separated with three intervening atoms
(e.g., I [8–11], II [12], III [13], IV [14,15] and V [16])
*
Corresponding author.
E-mail addresses: jainvk@apsara.barc.ernet.in (V.K. Jain), kaim@
iac.uni-stuttgart.de (W. Kaim), rbutcher@howard.edu (R.J. Butcher).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.09.019

1450
S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
S
H2
C
CH2S
Me
CH2
S
N
N
CH2CH2S
N
N
N
R2N
E
Me
Me
Me
Me
(I)
(II)
(IV)
(III)
(V)
E = S, Se, Te
3-aminopropyl
chalcogenolate (I)
pyrazolate based
thiolate (V)
N-methyl piperidyl based thiolates (II-IV)
Scheme 1.
(Scheme 1) have been investigated. In general, these ligands
act as a simple thiolate, however, in [MCl(S“N)]2 (M = Pd
or Pt; S“N = I–V) they function as chelating bridging li-
gands. The chemistry of the heavier analog of I (E = Se)
has been explored only recently by us [17]. We carried
out a reaction between [Pd(OAc)2]3 and [Pd(SeCH2CH2-
CH2NMe2)2]6 [18] with the hope of isolating a new struc-
tural motif as the substitution of acetate either in trimeric
[Pd(OAc)2]3 with ethyl(methylthio)acetate [19] or in tetra-
meric [Pt(OAc)2]4 with diethyldithiophosphate [20] results
in the formation of [Pd3(OAc)3(l,g2-MeSCHCOOEt)3] or
[Pt4(OAc)4{S2P(OEt)2}4], respectively. Surprisingly, the
complex of composition [Pd(OAc)(SeCH2CH2CH2N-
Me2)]n isolated from our reaction is dimeric as shown by
X-ray crystallography. We have further extended the work
with I, where E = S, Se, Te, and the results are summarized
herein.
heating rate of 10 ꢁC/min under a flow of argon. X-ray
powder diffraction was measured using Cu Ka radiation.
EDAX photographs were taken on a JEOL JSM-T330A
instrument.
2.1. Synthesis
2.1.1. Preparation of bis[3-(N,N-dimethylamino)propyl]-
disulfide, [(Me2NCH2CH2CH2S)2]
Bis(3-dimethylaminopropyl)disulfide was prepared in an
analogous manner to (Me2NCH2CH2CH2Se)2 [2], using
Me2NCH2CH2CH2Cl (40.41 g, 332 mmol) and Na2S2
(18.30 g, 166 mmol). The liquid was distilled in vacuo
(160 ꢁC/2 mm Hg) to give a pale-yellow liquid (22 g, 56%
yield). Spectroscopic data are given in Table 1.
2.1.2. Preparation of bis[3-(N,N-dimethylamino)propyl]-
ditelluride, [(Me2NCH2CH2CH2Te)2]
2. Experimental
The title compound was prepared from K2Te2 (37.96 g,
114 mmol) and Me2NCH2CH2CH2Cl (27.63 g, 227 mmol)
in a manner similar to the preparation of (Me2NCH2-
CH2CH2Se)2 [2], in 58% yield (28 g) as a dark red oil. This
oil on attempted distillation under vacuum led to excessive
decomposition (formation of Te metal). Therefore, the
crude dark red oil was extracted with hexane and cooled
at ꢀ5 ꢁC overnight. A white insoluble part separated in
variable yields and was not characterized. The hexane solu-
tion was passed through a Florisil column and the solvent
was evaporated under vacuum to give a red liquid (18 g,
37% yield) which was found to be spectroscopically pure
(Table 1).
All reactions were carried out under a nitrogen atmo-
sphere using conventional Schlenk techniques. Solvents
were dried by standard methods with subsequent distilla-
tion under nitrogen. Tellurium and Me2NCH2CH2CH2-
Cl Æ HCl were obtained from commercial sources. The
compound (Me2NCH2CH2CH2Se)2 and Na2PdCl4 were
prepared according to the literature methods [2]. Melting
points were determined in capillary tubes and are uncor-
rected. Elemental analyses were carried out by the Analyt-
ical Chemistry Division of B.A.R.C. 1H, 13C{1H},
77Se{1H} and 125Te{1H} NMR spectra were recorded on
a Bruker DPX-300 NMR spectrometer operating at 300,
75.47, 57.24 and 94.86 MHz, respectively. Chemical shifts
are relative to the internal chloroform peak at d 7.26 ppm
2.1.3. Preparation of [Pd(SCH2CH2CH2NMe2)2]6
To a methanolic solution (10 cm3) of NaSCH2CH2CH2-
NMe2 (prepared by NaBH4 (104 mg, 2.74 mmol), reduc-
tion of (Me2NCH2CH2CH2S)2 (318 mg, 1.34 mmol) in
methanol), a solution of Na2PdCl4 (395 mg, 1.34 mmol)
in methanol was added which was followed by addition
of 20 cm3 of acetone. The mixture was stirred for 4 h at
room temperature. The solvents were evaporated under
vacuum and the residue was extracted with hexane
(3 · 25 cm3). The brown solution was filtered through a
G-3 filter. The filtrate was concentrated to 15 cm3 and
was passed through a Florisil column. Few drops of
1
for H and d 77.0 ppm for 13C{1H}, Me2Se for 77Se{1H}
and [Te(dtc)2] (d = 0 ppm; dtc = N,N-diethyldithiocarba-
mate) for 125Te{1H}. A 90ꢁ pulse was used in every case.
The IR spectra were recorded as Nujol mulls between
CsI plates on a Bomen MB-102 FT-IR spectrometer.
UV–Vis absorption spectra were recorded on a Chemito
Spectrascan UV 2600 double beam UV–Vis spectropho-
tometer. Thermogravimetric analyses (TGA) were carried
out on a Setaram 92-16-18 instrument which was calibrated
with CaC2O4 Æ H2O. The TG curves were recorded at a

Table 1
Spectroscopic data for 3-dimethylaminopropyl chalcogenolate (E“N = Me2NCH2CH2CH2E; E = S, Se, Te) complexes of palladium(II)
Complex
NMR d in ppm in CDCl3
UV–Visa
IR in cmꢀ1
1H
13C{1H}
77Se{1H}/125Te{1H}
(Me2NCH2CH2CH2S)2
(Me2NCH2CH2CH2Se)2
(Me2NCH2CH2CH2Te)2
1.85 (m, C–CH2–C); 2.22 (s, NMe2); 2.35 (t, 7 Hz,
NCH2–); 2.72 (t, 7 Hz, SCH2)
1.90 (m, C–CH2–C); 2.20 (s, NMe2); 2.35 (t, 7 Hz,
NCH2); 2.95 (t, 7 Hz, SeCH2)
1.87 (m, C–CH2–C); 2.22 (s, NMe2); 2.40 (t,
6.6 Hz, NCH2–); 3.21 (t, 7.0 Hz, TeCH2)
1.98 (s, CH3)
2.21 (br, –CH2–); 2.26 (s, NMe2); 2.33, 2.40 (each
br, NCH2/SCH2)
27.2 (s, C–CH2–); 36.8 (s, –CH2–);
45.3 (s, NMe2); 58.2 (s, NCH2)
28.2 (SeCH2); 29.2 (s, C–CH2);
45.4 (s, NMe2); 59.3 (s, NCH2)
2.4 (s, TeCH2–); 30.5 (s, –CH2–);
45.6 (s, NMe2); 61.2 (s, NCH2)
22.7 (s, CH3); 188.5 (s, C@O)
30.7 (s, CH2); 33.0 (s, SCH2);
45.5 (s, NMe2); 58.8 (s, NCH2)
20.7, 24.7 (each s, SeCH2); 30.8,
32.6 (each s, SeC–CH2); 45.5 (s,
NMe2); 59.3, 59.5 (s, NCH2)
282 (180)
301 (770)
316
ꢀ653b
355 (586)
398 (255)
[Pd(OAc)2]3
[Pd(S“N)2]6
1601, 1564
258, 380
[Pd(Se“N)2]6
1.93–2.05 (m, SeC–CH2); 2.21, 2.23 (each s,
NMe2); 2.32–2.56 (m, NCH2, SeCH2)
ꢀ31, ꢀ161
298 (13800), 338 (9900),
440 (5000)
[Pd(Te“N)2]6
[PdCl(S“N)]2
decompose
316 (4450), 454 (4500)
2.32 (m, CH2); 2.46 (t, 5 Hz, NCH2); 2.75, 2.72
(each s, NMe2); 3.12 (m, SCH2)
26.8 (s, SCH2); 28.7 (s,
SCH2CH2); 50.8, 52.1 (each s,
NMe2); 63.1 (s, NCH2)
22.6 (s, 1J(77Se–13C) = 64 Hz,
SeCH2); 27.9 (s, SeCH2–CH2,
2J(Se–C) = 35 Hz); 50.0, 52.4
(each s, NMe2); 65.1 (s, NCH2)
285 (11400), 325 (sh),
368 (2100)
[PdCl(Se“N)]2
1.93–2.48 (m, NCH2CH2); 2.66, 2.74 (each s,
NMe2); 3.46–3.52 (m, SeCH2)
18
291
298 (10000), 335 (sh),
370 (sh)
[PdCl(Te“N)]2
324, 390
d
[Pd(OAc)(S“N)]2
1.97 (OAc); 2.47, 2.70 (each s, NMe2); 2.26 (m,
CCH2); 2.76 (m, NCH2); 2.95 (t, SCH2)
23.9 (s, OAc); 26.7, 27.0 (each s,
–CH2–/SCH2); 50.8 (s, NMe2);
63.1 (s, NCH2); 177.0 (C@O)
19.4 (CH2); 23.7 (OAc); 27.7 (s,
SeCH2); 50.0, 51.5 (NMe2); 64.4
(NCH2); 176.7 (C@O)
1580
1613
278 (12200), 351 (2300),
430 (sh)
[Pd(OAc)(Se“N)]2
1.95 (s, OAc); 2.45, 2.67 (each s, NMe2); 2.90–2.94
(m, SeCH2); 2.61–2.75 (br, m, NCH2); 2.25
(NCCH2)
ꢀ32
d
287 (19000), 291
(19000), 373 (sh), 442
(sh)
[Pd(SePh)(Se“N)]n
2.15 (with a very broad base); 7.10 (br); 7.94 (br)
24.8 (br, –CH2–); 32.6 (br,
SeCH2); 45.7 (s, NMe2); 59.6 (s,
NCH2); 126.8, 128.2, 131.2 (C-1);
135.9 [Ph]
c
299 (11600), 363 (sh),
419 (13200)
a
Wavelengths kmax at the absorption maxima in nm, molar extinction coefficients in Mꢀ1 cmꢀ1
Recorded in acetone-d6.
Spectra show broad resonances.
A broad peak appears at 1.69 due to coordinated water molecule, another peak appeared at 2.10 and could not be assigned.
.
b
c
d

1452
S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
pentane were added to yield (286 mg, 62%) a pasty solid at
ꢀ5 ꢁC. Analogous Se and Te complexes were prepared sim-
ilarly. Only prolonged cooling could give a crystalline
product. The tellurium complex decomposed on standing
and hence satisfactory analysis could not be done.
was concentrated to 5 cm3 and a few drops of hexane were
added to yield (64 mg, 44%) a chocolate colored powder.
2.1.7. Reaction between NaTeCH2CH2CH2NMe2 and
[Pd2Cl2(l-Cl)2(PEt3)2]
To a methanolic solution (10 cm3) of NaTeCH2CH2-
CH2NMe2 (prepared from (Me2NCH2CH2CH2Te)2
(124 mg, 0.29 mmol) and NaBH4 (22 mg, 0.58 mmol) in
methanol), an acetone (10 cm3) suspension of [Pd2Cl2
(l-Cl)2(PEt3)2] (170 mg, 0.29 mmol) was added with vigor-
ous stirring which was continued for 4 h. The solvents were
evaporated in vacuo and the residue was extracted with
hexane (3 · 10 cm3), followed by extraction with acetone
(3 · 8 cm3). Both hexane and acetone fractions were passed
through a Florisil column and the yellow solution was
dried under vacuum to give a yellow solid. M.p. 130 ꢁC.
Anal. Calc. for C12H30Cl2P2Pd: C, 34.8; H, 7.3. Found:
2.1.4. Preparation of [PdCl(TeCH2CH2CH2NMe2)]2
To a stirred methanolic solution (20 cm3) of Na2PdCl4
(731 mg, 2.48 mmol) was added a methanolic solution of
(Me2NCH2CH2CH2Te)2 (531 mg, 1.24 mmol). A brownish
yellow precipitate formed immediately. The reaction mix-
ture was stirred for 3 h. The solvent was evaporated under
vacuum and the residue was washed with hexane and meth-
anol (25 cm3). The residue was extracted with acetonitrile,
filtered and dried under vacuum, to give an orange solid
(238 mg, 27%). Analytical data are given in Table 2.
1
C, 33.6; H, 7.2; N, <0.2%. H NMR in acetone-d6 d: 1.18
(m, PC-CH3); 1.84–1.88 (m, PCH2), 31P{1H} in acetone-
d6 d: 18.6 ppm. Similarly, the reaction of [Pd2Cl2(l-Cl)2
(PPh3)2] with NaTeCH2CH2CH2NMe2 was carried out
2.1.5. Preparation of [Pd(OAc)(SCH2CH2CH2NMe2)]2 Æ
H2O
An acetone solution (5 cm3) of [Pd(OAc)2]3 (144 mg,
0.214 mmol) was added to a toluene solution (10 cm3) of
[Pd(SCH2CH2CH2NMe2)2]6 (153 mg, 0.074 mmol). The
reddish reaction mixture was stirred for 4 h. The solvents
were stripped off in vacuum. The residue was washed with
hexane and extracted with toluene (3 · 8 cm3). The red
solution was filtered and concentrated to 2 cm3. Few drops
of acetone and hexane were added and cooled at ꢀ5 ꢁC to
yield a yellow crystalline product (166 mg, 56%). Single
crystals were obtained from the supernatant at ꢀ5 ꢁC after
2 days. [Pd(OAc)(SeCH2CH2CH2NMe2)]2 was prepared in
an analogous manner.
and
a
mixture of products formed from which
PdCl2(PPh3)2 was isolated [Anal.: Calc. for C36H30Cl2P2Pd:
C, 61.6; H, 4.3. Found C, 60.2; H, 4.7; N, 0.4%. 31P{1H} in
acetone-d6 d: 23.7 ppm].
2.2. X-ray crystallography
X-ray data on single crystals of [Pd(OAc)(SCH2CH2CH2-
NMe2)]2 Æ H2O (2a Æ H2O), [Pd(OAc)(SeCH2CH2CH2NMe2)]2 Æ
H2O (2b Æ H2O) and [PdCl(TeCH2CH2CH2NMe2)]2 (3c)
were collected using graphite monochromated Mo Ka radi-
˚
ation (k = 0.71073 A), employing the x–2h scan technique.
Crystal data are given in Table3 [21–24]. The unit cellparam-
eters were determined from 25 reflections measured by ran-
dom search routine and indexed by the method of short
vectors followed by least-squares refinement. The intensity
data were corrected for Lorentz, polarization and absorp-
tion effects [25]. The structures were solved by direct methods
and refined by full-matrix least squares on F2. The non-
hydrogen atoms were refined anisotropically and the hydro-
gen atoms were introduced using the appropriate riding
model.
2.1.6. Preparation of [Pd(SePh)(SeCH2CH2CH2NMe2)]n
A dichloromethane solution (20 cm3) of [PdCl(SeCH2-
CH2CH2NMe2)]2 (104 mg, 0.34 mmol) was added to a
freshly prepared methanolic solution (5 cm3) of NaSePh
(prepared by NaBH4 (28 mg, 0.74 mmol) and reduction of
Ph2Se2 (108 mg, 0.34 mmol) in methanol). The color of the
reaction mixture immediately changed to dark chocolate.
The reactants were stirred for 3 h. The solvents were stripped
off in vacuo, the residue was washed with hexane and the res-
idue was extracted with toluene (3 · 10 cm3). The solution
Table 2
Physical and analytical data for 3-dimethylaminopropyl chalcogenolate (E“N = Me2NCH2CH2CH2E; E = S, Se, Te) complexes of palladium(II)
Complex
Recrystallization solvent (% yield)
Color/m.p. (ꢁC)
% Analysis Found (Calcd.)
C
H
N
[Pd(S“N)2]6
hexane (62)
hexane–pentane (40)
hexane (28)
dichloromethane (21)
dichloromethane–acetone (38)
acetonitrile (27)
acetone–hexane (56)
toluene–hexane (51)
toluene–hexane (44)
brown/paste
brown-red/102
brown/paste
orange-red/180 (d)
orange-red/205 (d)
red/106
brown/160 (d)
orange-red/156 (d)
red/96 (d)
34.7 (35.0)
26.4 (27.5)
17.7 (22.5)
22.8 (23.1)
19.3 (19.6)
16.5 (16.9)
28.3 (28.7)
24.7 (24.8)
30.9 (30.9)
7.1 (7.1)
5.3 (5.5)
3.8 (4.5)
4.4 (4.7)
3.6 (3.9)
3.6 (3.4)
6.1 (5.5)
4.9 (4.7)
4.9 (4.0)
7.9 (8.2)
5.3 (6.4)
3.8 (5.2)
5.5 (5.4)
5.0 (4.6)
4.2 (3.9)
4.7 (4.8)
4.1 (4.1)
3.1 (3.3)
a
[Pd(Se“N)2]6
[Pd(Te“N)2]6
[PdCl(S“N)]2
[PdCl(Se“N)]2
[PdCl(Te“N)]2
[Pd(OAc)(S“N)]2 Æ H2O
[Pd(OAc)(Se“N)]2 Æ H2O
[Pd(SePh)(Se“N)]n
a
S: Found 18.0; Calc. 18.7.

S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
1453
Table 3
Crystallographic and structure refinement data for 2a Æ H2O, 2b Æ H2O and 3c
2a Æ H2O
2b Æ H2O
3c
Chemical formula
Diffractometer model
Formula weight
C
14H32N2O5Pd2S2
C14H32N2O5Pd2Se2
Rigaku AFC-6S
679.14
0.56 · 0.35 · 0.10
103(2)
C10H24Cl2N2Pd2Te2
Siemens P4
711.21
0.35 · 0.30 · 0.10
173(2)
Nonius CAD4
585.34
0.2 · 0.2 · 0.1
293(2)
Crystal size (mm3)
Temperature (K)
˚
k (A)
0.71073
0.71073
0.71073
Crystal system
Space group
Unit cell dimensions
monoclinic
P21/c
monoclinic
P21/n
monoclinic
P21/n
˚
a (A)
12.5451(13)
12.1990(13)
15.649(3)
111.293(13)
2231.4(5)
12.522(3)
12.304(3)
15.465(3)
113.23(2)
2189.5(8)
2.060
4
10.765(2)
8.6628(17)
19.491(4)
98.05(3)
1799.8(6)
2.625
˚
b (A)
˚
c (A)
b (ꢁ)
Volume (A )
3
˚
Density calcd. (g cmꢀ1
Z
)
1.742
4
4
l (mmꢀ1)/F(000)
1.822/1176
2.18 to 24.98
ꢀ14 6 h 6 14, 0 6 k 6 14,
ꢀ1 6 l 6 18
1.132
w scan
3922/2772
2772/2/235
0.0377, 0.1094
0.0721, 0.1270
SHELXS 86 [21], SHELXL 97 [22]
4.992/1320
h for data collection (ꢁ)
Limiting indices
2.19 to 28.32
ꢀ14 6 h 6 16, ꢀ14 6 k 6 16,
ꢀ20 6 l 6 20
1.027
semi-empirical from equivalents
16407/5355
5355/3/232
0.0302, 0.0734
0.0383, 0.0769
TEXSAN [23]
2.11 to 27.02
ꢀ13 6 h 6 13, 0 6 k 6 11,
0 6 l 6 24
Goodness of fit on F2
Absorption correction
Reflections collected/unique
Data/restraints/parameters
Final R1, wR2 indices
R1, wR2 (all data)
1.091
empirical, XABS2
3900/3186
3186/0/167
0.0509, 0.1216
0.0678, 0.1333
SHELXTL-5.1 [24]
Computer programs used
3. Results and discussion
When treating complex 1 with Pd(OAc)2 or Na2PdCl4,
the formation of redistribution products [Pd(OA-
c)(ECH2CH2CH2NMe2)2]n (2) (E = S (2a) or Se (2b)) and
[PdCl(ECH2CH2CH2NMe2)]2 (3) (E = S (3a); Se (3b) or
Te (3c)), respectively, was observed. Compounds 3 can also
be obtained by the reaction of Na2PdCl4 with
(Me2NCH2CH2CH2E)2 in methanol as sparingly soluble
powders. Compounds 3a [11] and 3b [17] have been re-
ported earlier and their dimeric structures have been estab-
lished by X-ray crystallography. Like 1c, 2c and 3c
decompose in solution, most and rapidly in chlorinated sol-
vents (e.g., CH2Cl2 and CHCl3). The tellurolate complexes
of palladium and platinum are also known to decompose in
halogenated solvents [27]. Compound 3c, however, could
be stored in the solid state for several days without any
apparent decomposition and hence could be characterized
crystallographically. The reactions of 2b and 3b with Na-
3.1. Synthesis and spectroscopy
Bis(3-dimethylamino-1-propyl)dichalcogenides (Me2NCH2-
CH2CH2E)2 (E = S or Te) were prepared by the reaction
of Me2NCH2CH2CH2Cl with Na2S2 or K2Te2 in a manner
similar to the synthesis of (Me2NCH2CH2CH2Se)2 [17].
The disulfide and diselenide could be distilled under vacuum
as yellow and orange-red liquids, respectively, whereas the
ditelluride, a dark red oil, decomposed on attempted distilla-
tion. The NMR spectra (1H and 13C{1H}) displayed the ex-
pected resonances (Table 1). The 77Se{1H} and 125Te{1H}
NMR spectra exhibited only a single signal. These signals
appeared within the range reported for R2E2 (E = Se or
Te) [26].
Synthetic routes for palladium(II) 3-dimethylamino-1-
propylchalcogenolates are illustrated in Scheme 2. The
homoleptic palladium complexes, [Pd(ECH2CH2CH2N-
Me2)2]n (1) (E = S (1a); Se (1b) or Te (1c)), have been pre-
pared by the reaction of Na2PdCl4 with two equivalents of
NaECH2CH2CH2NMe2 in methanol–acetone. Compound
1b has been reported to have hexameric structure (from
FAB mass spectrometry and X-ray crystallography)
[11,17]. The spectroscopic data of 1a and 1c are similar
to those of 1b, suggesting that all these complexes have a
hexameric structure. Compound 1c tends to decompose
when left in solution, and hence no satisfactory microanal-
yses and NMR spectra could be obtained.
1
SePh gave [Pd(SePh)(SeCH2CH2CH2NMe2)]n (4). The H
and 13C{1H} NMR spectra of 2 and 3 displayed the ex-
pected resonances and peak multiplicities. The methyl
groups on NMe2 are anisochronous as two separate reso-
nances are observed both in the 1H and 13C NMR spectra.
One of the methyl resonances of the NMe2 group in the 1H
NMR spectra is considerably shielded (ꢁ2.45 ppm) for the
acetato complexes (2) as compared to its position for the
corresponding chloro complexes (3) (ꢁ2.70 ppm) (Table
1). This may be attributed to the anisotropic effect of the
carbonyl group on the methyl protons which lie below
the C@O group, according to the X-ray structural result.

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S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
(E∩N)2
[PdCl(E∩N)]2
Na2PdCl4
2NaE∩N
(3)
Na2PdCl4
2NaSePh; E = Se
NaE∩N
[Pd(E∩N)2]6
N
E
E
X
N
[Pd(SePh)(Se∩N)]n
Pd
Pd
(1)
(4)
X
[Pd(OAc)2]3
2NaSePh; E = Se
[Pd(OAc)(E∩N)]2
(2)
(E∩N)2 = (Me2NCH2CH2CH2E)2; E = S, Se or Te; X = Cl or OAc
Interconversion of palladium chalcogenolates
Scheme 2.
The reactions of [Pd2Cl2(l-Cl)2(PR3)2] with NaECHR0-
scheme are shown in Figs. 1 and 2 and the selected bond
lengths and angles are given in Tables 4 and 5.
CH2NMe2 (R0 = H or Me) have been reported to yield
[PdCl(ECHR0CH2NMe2)(PR3)] (E = S, Se, Te) [1–3]. To
assess whether 3-dimethylamino-1-propylchalcogenolate
can be used in a similar manner, the reactions of
NaECH2CH2CH2NMe2 (E = Se, Te) with [Pd2Cl2(l-Cl)2
(PR3)2] were carried out. In each case, a mixture of prod-
ucts was formed as revealed by 31P NMR spectroscopy.
From the reaction of [Pd2Cl2(l-Cl)2(PMePh2)2] with
NaSeCH2CH2CH2NMe2 (3b) could be separated [17].
The reaction of NaTeCH2CH2CH2NMe2 with [Pd2Cl2
(l-Cl)2(PR3)2] (PR3 = PEt3, PPh3) gave a mixture of prod-
ucts and from this mixture at least PdCl2(PR3)2 (R = Et or
Ph) could be isolated and characterized by microanalysis
and NMR (1H and 31P) spectral data.
The two structures are isomorphous and can be com-
pared with those of [PdCl(ECH2CH2CH2NMe2)]2 (E = S
[11] and Se [17]) and [PdCl(SC8H16N)]2 [12]. The two dis-
torted square planar palladium atoms in each molecule
are held together by asymmetric chalcogenolato-bridges.
Each palladium atom is surrounded by one oxygen atom
of OAcꢀ, one nitrogen and two chalcogen atoms. The ace-
tate groups are in anti position. One water molecule is
hydrogen bonded to the carbonyl oxygen atom of the ace-
tate group. The six-membered chelate rings (PdECCCN)
are in boat conformation, while the four-membered
‘‘Pd2E2’’ ring is non-planar.
Although the Pd–E distances trans to N are longer than
those trans to the acetate linkages, they are well within the
range reported for several complexes [11,12,16,17]. In con-
trast, the Pd–E distances in [PdCl(ECH2CH2CH2NMe2)]2
are essentially similar [11,12,17]. The Pd–O distances in
3.2. Electronic spectra
The absorption spectra of the complexes display long
wavelength bands in dichloromethane (Table 1). These
absorptions can be assigned as charge transfer transitions
from electron-rich chalcogenolate ligand centers to unoccu-
pied metal orbitals (LMCT). The absorptions of the
complexes [Pd(ECH2CH2CH2NMe2)2]6 are intense and
red-shifted in comparison to the corresponding complexes
[PdCl(ECH2CH2CH2NMe2)]2. The absorptions of the ace-
tato complexes 2 are considerably red-shifted in compari-
son to corresponding chloro derivatives 3.
3.3. Crystal structures of [Pd(OAc)(ECH2CH2CH2NMe2)]2 Æ
H2O (E = S or Se)
The structures of [Pd(OAc)(ECH2CH2CH2NMe2)]2
(E = S or Se), which crystallized with one molecule of
water, were confirmed by single crystal X-ray diffraction
methods. The ORTEP plots with atomic numbering
Fig. 1. Molecular structure of [Pd(OAc)(SCH2CH2CH2NMe2)]2 Æ H2O
with atomic numbering scheme.

S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
1455
Table 5
˚
Selected bond lengths (A) and angles (ꢁ) for [Pd(OAc)-(SeCH2CH2-
CH2NMe2)]2 Æ H2O
Pd(1)–O(1A)
Pd(1)–N(1A)
Pd(1)–Se(1A)
Pd(1)–Se(1B)
O(1A)–C(6A)
O(2A)–C(6A)
O(1B)–C(6B)
O(2B)–C(6B)
2.053(3) Pd(2)–O(1B)
2.129(3) Pd(2)–N(1B)
2.3776(8) Pd(2)–Se(1B)
2.3952(6) Pd(2)–Se(1A)
1.255(4) Se(1A)–C(1A)
1.260(5) Se(1B)–C(1B)
1.292(5) O(1W)–H(1W1)
1.232(6) O(1W)–H(1W2)
2.078(3)
2.141(3)
2.3742(6)
2.4025(5)
1.974(4)
1.966(4)
0.842(19)
0.847(19)
O(1A)–Pd(1)–N(1A) 90.19(11) O(1B)–Pd(2)–N(1B)
94.76(12)
169.07(8)
94.57(9)
91.01(8)
172.84(9)
80.14(2)
102.19(13)
105.03(12)
87.21(2)
O(1A)–Pd(1)–Se(1A) 170.18(8)
N(1A)–Pd(1)–Se(1A) 96.41(8)
O(1A)–Pd(1)–Se(1B) 93.80(8)
N(1A)–Pd(1)–Se(1B) 174.02(8)
O(1B)–Pd(2)–Se(1B)
N(1B)–Pd(2)–Se(1B)
O(1B)–Pd(2)–Se(1A)
N(1B)–Pd(2)–Se(1A)
Se(1A)–Pd(1)–Se(1B) 80.221(17) Se(1B)–Pd(2)–Se(1A)
C(1A)–Se(1A)–Pd(1) 103.47(13) C(1B)–Se(1B)–Pd(2)
C(1A)–Se(1A)–Pd(2) 106.43(12) C(1B)–Se(1B)–Pd(1)
Fig. 2. Molecular structure of [Pd(OAc)(SeCH2CH2CH2NMe2)]2 Æ H2O
with atomic numbering scheme.
Pd(1)–Se(1A)–Pd(2)
86.97(2)
Pd(2)–Se(1B)–Pd(1)
C(6A)–O(1A)–Pd(1) 121.1(2)
C(6B)–O(1B)–Pd(2) 114.6(3)
O(1A)–C(6A)–O(2A) 124.3(4)
O(1A)–C(6A)–C(7A) 115.4(4)
O(2A)–C(6A)–O(7A) 120.1(4)
Pd(1)–N(1A)–C(3A) 114.9(2)
Pd(1)–N(1A)–C(4A) 104.1(2)
Pd(1)–N(1A)–C(5A) 111.9(2)
H(1W1)–O(1W)–H(1W2) 105(3)
Table 4
O(1B)–C(6B)–O(2B)
O(1B)–C(6B)–O(7B)
O(2B)–C(6B)–O(7B)
Pd(2)–N(1B)–C(3B)
Pd(2)–N(1B)–C(4B)
Pd(2)–N(1B)–C(5B)
123.9(4)
114.5(4)
121.6(4)
116.0(2)
106.2(2)
109.7(3)
˚
Selected bond lengths (A) and angles (ꢁ) for [Pd(OAc)(SCH2CH2-
CH2NMe2)]2 Æ H2O
Pd(1)–S(1)
Pd(1)–S(2)
Pd(2)–S(1)
Pd(2)–S(2)
Pd(1)–O(1)
C(6)–O(2)
C(6)–O(1)
C(6)–C(7)
2.292(2)
2.268(2)
2.263(2)
2.291(2)
2.061(6)
1.220(13)
1.268(11)
1.488(16)
Pd(2)–O(3)
Pd(1)–N(1)
Pd(2)–N(2)
S(1)–C(8)
2.066(6)
2.129(7)
2.131(7)
1.840(9)
1.822(10)
1.225(14)
1.264(13)
1.522(15)
S(2)–C(1)
C(13)–O(4)
C(13)–O(3)
C(13)–C(14)
3.4. Crystal structure of [PdCl(TeCH2CH2CH2NMe2)]2
The molecular structure of 3c is shown in Fig. 3, it is
comparable to those of [PdCl(ECH2CH2CH2NMe2)]2
(E = S or Se). Two distorted square planar palladium
atoms in the molecule are held together by two tellurolate
bridges of the chelating TeCH2CH2CH2NMe2 ligands.
The coordination environment around each palladium
atom is defined by two Te atoms, N and Cl. The two chlo-
ride ligands are mutually trans. The four-membered Pd2Te2
ring is non-planar. The Pd–Te distances trans to N and
trans to Cl are essentially similar. The Pd–Cl [17,30], Pd–
N [17,30] and Pd–Te [2,30] distances (Table 6) are well
within the range reported for palladium(II) derivatives.
S(1)–Pd(1)–S(2)
S(1)–Pd(1)–O(1)
S(1)–Pd(1)–N(1)
S(2)–Pd(1)–N(1)
S(2)–Pd(1)–O(1)
N(1)–Pd(1)–O(1)
Pd(1)–S(1)–Pd(2)
C(6)–O(1)–Pd(1)
O(2)–C(6)–O(1)
O(2)–C(6)–C(7)
O(1)–C(6)–C(7)
Pd(1)–N(1)–C(3)
Pd(1)–N(1)–C(4)
Pd(1)–N(1)–C(5)
Pd(1)–S(2)–C(1)
Pd(1)–S(1)–C(8)
79.47(8)
93.7(2)
172.69(19)
95.9(2)
169.23(19)
91.7(3)
88.16(7)
121.1(7)
124.1(11)
120.8(11)
115.1(11)
116.2(7)
112.6(6)
105.6(6)
107.1(4)
108.4(3)
S(1)–Pd(2)–S(2)
S(2)–Pd(2)–O(3)
S(2)–Pd(2)–N(2)
S(1)–Pd(2)–N(2)
S(1)–Pd(2)–O(3)
N(2)–Pd(2)–O(3)
Pd(1)–S(2)–Pd(2)
C(13)–O(3)–Pd(2)
O(4)–C(13)–O(3)
O(4)–C(13)–C(14)
O(3)–C(13)–C(14)
Pd(2)–N(2)–C(10)
Pd(2)–N(2)–C(11)
Pd(2)–N(2)–C(12)
Pd(2)–S(1)–C(8)
Pd(2)–S(2)–C(1)
79.59(8)
91.76(19)
172.4(2)
95.3(2)
168.9(2)
94.0(3)
88.08(8)
117.6(8)
124.1(10)
121.6(11)
114.3(12)
115.3(5)
106.5(6)
109.9(6)
106.2(3)
109.4(3)
3.5. Thermal studies
Pd(1)ꢂ ꢂ ꢂPd(2) 3.1689(9).
These studies were conducted to assess whether these
complexes can be used as precursors for the synthesis of pal-
ladium chalcogenides, which can find applications in catal-
ysis and in the electronics industry [31]. Thus, the thermal
behavior of [Pd(OAc)(SeCH2CH2CH2NMe2)]2 Æ H2O (2b)
was investigated. The TG curve (Fig. 4) showed a three step
decomposition with a total weight loss of 47.7%, which cor-
responds to Pd17Se15 (calcd. weight loss 48.1%). In the first
step of decomposition at 130 ꢁC, the coordinated water
molecule is liberated. The second step of decomposition at
175 ꢁC leads to the formation of PdSe (from weight loss
45.6%; calcd. 45.4%), which finally loses some selenium at
260 ꢁC to give the single phase of Pd17Se15. The latter is also
obtained when a bulk quantity of 2b is heated at 300 ꢁC
the two molecules are slightly longer than those reported in
[Pd(OAc)2]3 (Pd–O = 1.973–2.014(9) A) [28] and [Pd(8-
hydroxyquinolinate)2] (2.02(2) A) [29], owing to the strong
˚
˚
trans influence of the chalcogen ligand trans to the acetate
group. The Pdꢂ ꢂ ꢂPd separation in acetato complexes (for S:
˚
˚
3.1689(9) A; Se: 3.289(9) A) is significantly reduced in com-
parison to the corresponding chloro analogs (for S:
˚
˚
3.305(1) A [11]; Se: 3.413(1) A [17]). The E–Pd–E and
Pd–E–Pd angles in the acetato complexes are ꢁ8ꢁ and
86–88ꢁ, respectively. The corresponding angles in the
chloro derivatives have been reported to be 80ꢁ and 90–
93ꢁ, respectively [11,17].

1456
S. Dey et al. / Inorganica Chimica Acta 359 (2006) 1449–1457
under flowing argon atmosphere. The XRD pattern of the
residue confirms the formation of Pd17Se15 [32].
In conclusion, the chemistry of the 3-dimethylamino-1-
propylchalcogenolate ligands differs considerably from that
of 2-aminoalkylchalcogenolates, both in terms of coordina-
tion behavior and chemical reactivity. The acetato deriva-
tives show promising potential as low temperature
decomposition precursors for the synthesis of palladium
chalcogenides.
4. Supplementary material
CCDC Nos. 268184 ([Pd(OAc)(SeCH2CH2CH2NMe2)]2 Æ
H2O), 277357 ([Pd(OAc)(SCH2CH2CH2NMe2)]2 Æ H2O)
and 277356 ([PdCl(TeCH2CH2CH2NMe2)]2) contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge at www.ccdc.cam.
ac.uk/conts/retrieving.html or from the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK [Fax: (internat.) + 44 1223/336 033; E-mail:
deposit@ccdc.cam.ac.uk].
Fig. 3. Molecular structure of [PdCl(TeCH2CH2CH2NMe2)]2 with atomic
numbering scheme.
Table 6
˚
Selected bond lengths (A) and angles (ꢁ) for [PdCl(TeCH2CH2-
CH2NMe2)]2
Acknowledgments
Pd(1)–Te(1)
Pd(1)–Te(2)
Pd(1)–Cl(1)
Pd(1)–N(1)
Te(1)–C(15)
2.5532(9)
2.5467(11)
2.361(2)
2.174(8)
2.173(10)
Pd(2)–Te(2)
Pd(2)–Te(1)
Pd(2)–Cl(2)
Pd(2)–N(2)
Te(2)–C(25)
2.5395(10)
2.5520(10)
2.386(3)
2.177(8)
2.166(10)
We thank Drs. T. Mukherjee and S.K. Kulshreshtha for
encouragement of this work. We are also grateful to Dr. M.
Sudershanan, Head, Analytical Chemistry Division,
BARC for providing microanalyses of the complexes.
Te(1)–Pd(1)–Te(2)
Te(1)–Pd(1)–Cl(1)
Te(2)–Pd(1)–Cl(1)
Te(1)–Pd(1)–N(1)
Te(2)–Pd(1)–N(1)
Cl(1)–Pd(1)–N(1)
Pd(1)–Te(1)–Pd(2)
Pd(1)–Te(1)–C(15)
Pd(2)–Te(1)–C(15)
79.36(3)
169.64(7)
90.29(7)
96.0(2)
175.2(2)
94.3(2)
90.06(3)
98.6(3)
103.3(3)
Te(1)–Pd(2)–Te(2)
Te(2)–Pd(2)–Cl(2)
Te(1)–Pd(2)–Cl(2)
Te(2)–Pd(2)–N(2)
Te(1)–Pd(2)–N(2)
Cl(2)–Pd(2)–N(2)
Pd(2)–Te(2)–Pd(1)
Pd(1)–Te(2)–C(25)
Pd(2)–Te(2)–C(25)
79.52(3)
170.43(7)
90.95(7)
94.8(2)
173.4(2)
94.6(2)
90.49(3)
107.8(3)
100.8(3)
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