Binuclear orthometalated N,N-Dimethylbenzylamine complexes of palladium(II): Synthesis, structures and thermal behavior

Article abstract of DOI:10.1080/10426507.2012.757608

Organochalcogenolate-bridged cyclometalated palladium(II) complexes of the formulae, [Pd₂(μ-Epy)₂(Me₂NCH ₂C₆H₄-C,N)₂] (2) (E = S (2a), Se (2b)), [Pd₂(μ-SAr)(μ-Cl)(Me₂NCH₂C ₆H₄-C,N)₂] (3) (Ar = Ph (3a), Mes (Mes = 2,4,6-Me₃C₆H₂) (3b)) and [Pd ₂(μ-SeAr)₂(Me₂NCH₂C ₆H₄-C,N)₂] (4) (Ar = Ph (4a), Mes (4b)), have been synthesized by the reactions of [Pd₂(μ-Cl) ₂(Me₂NCH₂C₆H₄-C,N) ₂] with lead or sodium salts of the chalcogenolate ligand. These complexes have been characterized by elemental analysis, mass spectral data, and NMR (¹H and ⁷⁷Se{¹H}) spectroscopy. The molecular structure of 2, determined by single crystal X-ray diffraction analysis, revealed a Epy-bridged head-to-tail arrangement in which the eight-membered (PdECN)₂ ring adopts a distorted twist boat conformation. The Pd····Pd separation in 2a is within the van-der-Waals interaction but in 2b it is too large to support the presence of any metal-metal interaction. The thermal behavior of these complexes has been studied by thermogravimetric analysis.

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Binuclear Orthometalated N,N-
Dimethylbenzylamine Complexes of
Palladium(II): Synthesis, Structures and
Thermal Behavior
Siddhartha Kolay a , Ninad Ghavale a , Amey Wadawale a , Dasarathi
Das a & Vimal K. Jain a
a Chemistry Division , Bhabha Atomic Research Centre , Mumbai ,
400085 , India
Accepted author version posted online: 02 Jan 2013.Published
online: 06 Sep 2013.
To cite this article: Siddhartha Kolay , Ninad Ghavale , Amey Wadawale , Dasarathi Das & Vimal
K. Jain (2013) Binuclear Orthometalated N,N-Dimethylbenzylamine Complexes of Palladium(II):
Synthesis, Structures and Thermal Behavior, Phosphorus, Sulfur, and Silicon and the Related Elements,
188:10, 1449-1461, DOI: 10.1080/10426507.2012.757608
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Phosphorus, Sulfur, and Silicon, 188:1449–1461, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.757608
Binuclear Orthometalated N,N-Dimethylbenzylamine
Complexes of Palladium(II): Synthesis, Structures and
Thermal Behavior
Siddhartha Kolay, Ninad Ghavale, Amey Wadawale,
Dasarathi Das, and Vimal K. Jain
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
GRAPHICAL ABSTRACT
Abstract Organochalcogenolate-bridged cyclometalated palladium(II) complexes of the
formulae, [Pd2(μ-Epy)2(Me2NCH2C6H4-C,N)2] (2) (E = S (2a), Se (2b)), [Pd2(μ-SAr)(μ-
Cl)(Me2NCH2C6H4-C,N)2] (3) (Ar = Ph (3a), Mes (Mes = 2,4,6-Me3C6H2) (3b)) and [Pd2(μ-
SeAr)2(Me2NCH2C6H4-C,N)2] (4) (Ar = Ph (4a), Mes (4b)), have been synthesized by the
reactions of [Pd2(μ-Cl)2(Me2NCH2C6H4-C,N)2] with lead or sodium salts of the chalcogeno-
late ligand. These complexes have been characterized by elemental analysis, mass spectral
1
data, and NMR (1H and 77Se{ H}) spectroscopy. The molecular structure of 2, determined by
single crystal X-ray diffraction analysis, revealed a Epy-bridged head-to-tail arrangement in
Received 1 August 2012; accepted 7 December 2012.
The authors thank Dr. T. Mukherjee for encouragement of this work.
Address correspondence to Vimal K. Jain, Chemistry Division, Bhabha Atomic Research Centre, Mumbai
400085, India. E-mail: jainvk@barc.gov.in
1449

1450
S. KOLAY ET AL.
which the eight-membered “(PdECN)2” ring adopts a distorted twist boat conformation. The
Pd····Pd separation in 2a is within the van-der-Waals interaction but in 2b it is too large to
support the presence of any metal–metal interaction. The thermal behavior of these complexes
has been studied by thermogravimetric analysis.
Supplementary materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental
files: Additional figures.
Keywords Cyclometaled complexes; palladium; chalcogen ligands; x-ray structure,
NMR, TGA
INTRODUCTION
Cyclometalated platinum group metal complexes have been of considerable inter-
est1–3 since early studies by Cope and Siekman in the mid 1960s. Recently we have isolated
cyclometalated palladium and platinum complexes derived from metalated ligand differing
in the metalocyclic ring size and the nature of neutral donor group as well as a variety of
anionic auxiliary ligands.4–7 It is worth noting that simple thiolate ligands invariably gave
chloro/thiolato-bridged derivatives of palladium, [Pd2(μ-Cl)(μ-SR)(CˆN)2] under differ-
ent experimental conditions.4 In contrast, similar reactions with selenolate ligands afforded
bis-selenolato-bridged derivatives.4 Such reactions employing platinum precursors and both
thiolate and selenolate ligands yielded the expected products, [Pt2(μ-ER)2(X∩C)2] (E = S
or Se; X = N or P).5,6 Interestingly, reaction involving platinum precursors with internally
functionalized ligands, e.g., Spy, Me2NCH2CH2E− (E = S or Se) afforded several products
varying from cleavage of metalated ligands, cleavage of the Pt-C bond, mono-, bi- and tetra-
nuclear platinum(II) complexes to a platinum(III) derivative [Pt2Cl2(μ-Spy)2(ppy)2].5–7 The
2-mercaptopyridine bridged platinum complex with metalated 2-phenylpyridine show a fa-
cial redox (PtII····PtIII) behavior8 and exhibit red luminescence from metal to metal ligand
charge transfer (MMLCT) arising from short Pt····Pt (2.849(1) Å) interaction.8,9 Similarly,
other Spy-bridged binuclear complexes of palladium(II) and platinum(II) with short M····M
(M = Pd or Pt) interactions, e.g., [Pd2(μ-Spy)2(CˆN)2],10 [Pt2(μ-Spy)2(bipy)2][PF6]2,11
have been shown to be luminescent.10–12 Deeming and coworkers13 reported Spy and
SpyMe (6-methylpyridine-2-thiolate) bridged binuclear palladium complexes derived from
metalated N,N-dimethylbenzylamine, [Pd2(μ-SAr)2(Me2NCH2C6H4-C,N)2] (Ar = py or
C5H3(6-Me)N) and described the structural aspects based on 1H NMR spectral data.
In the light of the above we have now examined palladium(II) complexes containing
N,N-dimethylbenzylamine as a metalated ligand and pyridine-2-chalcogenolate ions as a
bridging ligand. For comparison purpose complexes with non-hemilabile chalcogenolate
ligands bearing bulky (Mes = 2,4,6-Me3C6H2-) and simple (Ph) aryl groups have also been
synthesized. Results of this work are described herein.
RESULTS AND DISCUSSION
Synthesis and Spectroscopy
The reaction of [Pd2(μ-Cl)2(Me2NCH2C6H4 C,N)2] (1) with lead salt of 2-
mercapto or selenopyridine in dichloromethane afforded 2-chalcogenopyridine-bridged
binuclear palladium complexes, [Pd2(μ-Epy)2(Me2NCH2C6H4-C,N)2] (2) (E = S (2a) or
Se (2b) ) in fairly good yield (Scheme 1). Interestingly, a similar reaction with simple

BINUCLEAR ORTHOMETALATED N,N-DIMETHYLBENZYLAMINE COMPLEXES 1451
arylthiolate groups gave mixed chloro/mercapto-bridged derivatives, [Pd2(μ-Cl)(μ-
SAr)(Me2NCH2C6H4 C,N)2] (3) (Ar = Ph (3a) or Mes (3b)). Contrary to this, the
analogous arylselenolate ligand yielded the expected bis selenolato-bridged complexes,
[Pd2(μ-SeAr)2(Me2NCH2C6H4-C,N)2] (4) (Ar = Ph (4a) or Mes (4b)).
Scheme 1
The mass spectra of 2 did not show a molecular ion peak, instead a peak due to M-Epy
fragment with the expected isotopic pattern was observed. The mass spectra of 3 and 4
displayed molecular ion peaks. The 1H NMR spectral data for 2a are consistent with the one
reported earlier.13 Deeming described temperature independent 1H NMR spectra of 2a while
the analogous complex [Pd2(μ-SC5H3(Me-6)N)2(Me2NCH2C6H4-C,N)2] is fluxional at
1
room temperature.13 Unlike 2a, the H NMR spectrum of 2b showed broad resonances
indicative of fluxional nature of the complex in solution. The spectrum displayed a singlet
for NMe2 protons and two separate resonances for CH2 protons, i.e., a singlet at 2.97 ppm
and a broad AB pattern in the region 3.13– 3.37 ppm in the ratio of 1:1.6 at room temperature.
On lowering the temperature, two separate signals for NMe2 protons appeared. At –30 ◦C,
the spectrum showed two separate signals for NMe2 at 2.49 and 2.52 ppm while the NCH2
protons showed a singlet at 2.97 ppm and an AB pattern in the region 3.05-3.14 ppm in the
ratio of 1:8.8. The singlet at 2.97 ppm may be attributed to the sym-cis isomeric form. The
spectra of 3 and 4 exhibited singlets for NMe2 and CH2 protons at ∼2.75 and ∼3.85 ppm,
respectively, indicating magnetic equivalence of protons of methyl and methylene groups.
This suggests that these groups of both the metalated ligands are trans to the similar
bridging ligands. Recent X−ray analysis of [Pd2(μ-Cl)(μ−SMes)(Me2NC10H6 C,N)2]4
and [Pd2(μ-Cl)(μ−SBun){(BunO)C6H3CH = NC6H4(OBun−4)}2]14 have shown a sym-cis
configuration with the nitrogen atom of the metalated ligands trans to the bridging thiolate
group. The 1H NMR spectra of 3 can be interpreted in terms of sym-cis configuration. The
77Se NMR spectrum of 4a showed a singlet at 181 ppm indicating that both the bridging
selenolates are magnetically equivalent as is expected for sym-trans configuration. However,

1452
S. KOLAY ET AL.
for 4b 77Se NMR spectrum displayed two resonances at –10 and 30 ppm indicating the
existence of sym-cis configuration. This configuration has been reported for the complex
[Pd2(μ-SePh)2(Me2NC10H6 C,N)2] both in the solid state (X−ray crystallography) and
in solution (77Se NMR data).4
Crystal Structures of [Pd2(μ–Epy)2(Me2NCH2C6H4–C,N)2] (E = S or Se)
Molecular structures of [Pd2(μ–Epy)2(Me2NCH2C6H4–C,N)2] (E = S or Se), es-
tablished by X–ray diffraction analysis, are shown in Figures 1 and 2, while the se-
lected inter-atomic parameters are given in Tables 1 and 2. The coordination around
each palladium atom, defined by C, N, E, N, donor set, is nearly planar. The sul-
fur or selenium atoms in the two bridging pyridine-chalcogenolate ligands occupy the
trans position to the N atoms of the metalated ligands resulting in an anti configuration
(head-to-tail arrangement) which is usually observed for this type of complexes.10,11,15
Figure 1 Crystal structure of [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2] with 25% ellipsoid probability (H atoms
are excluded for clarity) (Color figure available online).

BINUCLEAR ORTHOMETALATED N,N-DIMETHYLBENZYLAMINE COMPLEXES 1453
Figure 2 Crystal structure of [Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2] with 25% ellipsoid probability (H atoms
are excluded for clarity) (Color figure available online).
The eight-membered ring adopts a distorted twist-boat conformation. The methyl groups
of NMe2 of the metalated rings are mutually anti but differ in their conformation in
two complexes. In case of the Spy bridged complex, they are exo with resepect to
the eight-membered boat configuration while in the case of Sepy-bridged complex they
adopt an endo configuration. The Pd–C and Pd–N(metalated) are well in agreement with
those reported for [Pd3(μ–Spy)2(Me2NCH2C6H4–C,N)3][BF4]13 and other related cy-
clometalated palladium complexes.14 The two Pd–S distances are essentially similar and
can be compared with those reported in [Pd3(μ–Spy)2(Me2NCH2C6H4–C,N)3][BF4],13
[Pd2(μ–Spy)2(Bzq)2],10 and [Pd2(μ–Spy)2(4,4ꢁ–But2bipy)2][ClO4]2.12 The Pd–Se distance
(2.410Å) is as expected and can be compared with the one trans to nitrogen atom as observed
in [Pd2(μ–SePh)2(C10H6NMe2–C,N)2].4

1454
S. KOLAY ET AL.
Table 1 Selected bond lengths (Å) and angles ( ◦) for [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2]
Pd1-C11
Pd1-N2
Pd1-N3
Pd1-S1
S1-C1
2.028(8)
2.184(7)
2.143(6)
2.295(2)
1.728(9)
Pd2-C20
Pd2-N1
Pd2-N4
Pd2-S2
S2-C6
Pd1-Pd2
N1-Pd2-N4
N1-Pd2-S2
N1-Pd2-C20
N4-Pd2-C20
N4-Pd2-S2
C20-Pd2-S2
N1-C1-S1
C20-Pd2-Pd1
2.004(8)
2.157(7)
2.163(6)
2.305(2)
1.732(8)
2.976(2)
93.4(2)
91.37(18)
174.7(3)
82.1(3)
N2-Pd1-N3
N2-Pd1-S1
N2-Pd1-C11
N3-Pd1-C11
N3-Pd1-S1
C11-Pd1-S1
N1-C6-S2
92.7(2)
92.81(18)
174.0(3)
81.6(3)
166.84(19)
92.2(2)
167.55(17)
92.5(2)
122.4(6)
98.5(2)
122.2(6)
98.6(2)
C11-Pd1-Pd2
The Pd–Pd distance in Spy-bridged complex (2.976(2) Å) is significantly longer
than those reported in [Pd2(Spy)4] (2.677(1) Å),16 [Pd2(μ–Spy)2(4,4ꢁ–But2bipy)2][ClO4]2
(2.891(4)Å),12 [Pt2(Spy)2(ppy)2] (2.8491(4) Å),8 but only marginally longer than the one
reported in [Pd2(μ–Spy)2(Bzq)2] (2.941(4) Å).10 However, it is shorter than the sum of van
der Waals radii of Pd atoms (3.26Å) and is within the acceptable value for a Pd···Pd intra-
molecular interaction. The Pd···Pd separation in the corresponding Sepy bridged complex
(3.420Å) is much longer than the analogous thio derivative and is also longer than the sum
of van der Waals radii of Pd atoms indicative of absence of Pd···Pd interaction.
Thermal studies
Palladium chalcogenolate complexes have been employed as molecular precursors
for moderately low temperature synthesis of palladium chalcogenides4,17,18 which find nu-
merous applications.19,20 These are also believed to be formed during several catalytic
processes involving palladium chalcogenolate complexes.21,22 Depending on auxiliary lig-
ands on palladium and the nature of R group on chalcogenolate ligand, a variety of palladium
chalcogenides are formed. To understand decomposition pattern of these complexes ther-
mogravimetric analysis (TGA) were carried out and the TG residues were characterized by
powder XRD. Some of these complexes were also heated in a furnace under different heating
conditions and the final residues were characterized by powder XRD analysis. The TG-
DTG curves (Supplementary Material) revealed that these complexes undergo a multistep
decomposition in the temperature range 200–300 ◦C leading to the formation of palladium
Table 2 Selected bond lengths (Å) and angles ( ◦) for [Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2]
Pd1-C6
Pd1-N1
Pd1-N2
N1-Pd1-N2
N1-Pd1-Se1i
N1-Pd1-C6
1.994(9)
2.189(8)
2.140(8)
94.3(3)
94.7(2)
173.6(4)
Pd1-Se1i
Se1-C5
Pd1-Pd1i
N2-Pd1-C6
N2-Pd1-Se1i
C6-Pd1-Se1i
N1-C5-Se1
2.410(2)
1.906(10)
3.420
81.4(4)
165.2(2)
88.5(3)
118.3(7)

BINUCLEAR ORTHOMETALATED N,N-DIMETHYLBENZYLAMINE COMPLEXES 1455
10
0
2
0
-2
-10
-20
-30
-40
-50
-60
-4
-6
-8
-10
-12
-14
50
100
150
200
250
300
350
400
Temperature °C
Figure 3 TG-DTG curve of [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2] (Color figure available online).
chalcogenides. The thiolato-bridged complexes decomposed to single phase Pd4S (JCPD
file No 73-1387). The TG curve (Figure 3) of [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2] ap-
pears to be a single-step decomposition but the DTG clearly shows overlapping of closely
◦
spaced two-step decomposition (weight loss 30, 28%) at ∼215 C with the formation of
Pd4S (from XRD pattern, Figure 4). This complex can be converted into single phasic Pd4S
500
400
300
200
100
0
30
35
40
45
50
55
60
65
2θ
Figure 4 XRD pattern of Pd4S obtained from [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2].

1456
S. KOLAY ET AL.
0
-10
-20
-30
-40
0
-2
-4
50
100
150
200
250
300
350
400
450
Temperature °C
Figure 5 TG-DTG curve of [Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2] (Color figure available online).
◦
even at low temperature (210 C) as seen during the conventional furnace heating under
dynamic argon flow condition.
The selenolato-bridged complexes in general gave a mixture of palladium selenides
on decomposition. The TG curve of [Pd2(μ-SePh)2(Me2NCH2C6H4–C,N)2] showed that
the complex decomposed at ∼290 ◦C into single phasic Pd7Se4 (confirmed from the XRD
pattern JCPDS 44-0875). We have also tried to identify the low temperature decomposition
◦
product by carrying out the decomposition of the complex at 200 C in a furnace under
flowing argon, air, and H2 atmospheres. However, in every case, Pd4Se was the major
product together with Pd7Se4 as confirmed from their powder XRD patterns. Similarly,
[Pd2(μ-SeMes)2(Me2NCH2C6H4–C,N)2] decomposed into a biphasic mixture of Pd34Se11
(JCPDS file No: 79-0140) and Pd4Se7 (JCPDS file No: 31-0939) at ∼350 ◦C. The complex
[Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2] undergoes a multi-step decomposition (Figure 5)
◦
at 225 C to yield Pd17Se15 as confirmed by the XRD pattern (Figure 6) (JCPDS file No
73-1424). Figures S2–S12 (Supplemental Materials) provide additional characterization
spectra for TG-DTG and XRD of the products.
EXPERIMENTAL
Materials and Methods
Solvents were dried and distilled under a nitrogen atmosphere prior to use accord-
ing to literature method.23 All reactions were carried out in Schlenk flask under a ni-
trogen atmosphere. N,N-Dimethylbenzylamine, PhSH, MesSH (Mes = 2,4,6-Me3C6H2),
Ph2Se2, pySH, and other reagents were obtained from commercial sources and were used
without further purification. Palladium precursor [Pd(μ-Cl)(C∩N)]2 (1) (C∩NH = N,N-
dimethylbenzylamine),24 Mes2S2,25 Mes2Se2,26 py2Se2,27 Pb(SMes)2,18 and Pb(Spy)2
7
were prepared according to literature methods. Elemental analyses were carried out on a

BINUCLEAR ORTHOMETALATED N,N-DIMETHYLBENZYLAMINE COMPLEXES 1457
300
200
100
0
20
30
40
50
60
70
2θ
Figure 6 XRD pattern of Pd17Se15 obtained from [Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2].
Thermo Fisher Flash CHN-S instrument. Melting points were determined in capillary tubes
and are uncorrected. UV-vis spectra were recorded on a Chemito Spectroscan UV-2600
1
double beam UV-vis spectrophotometer. 1H and 77Se{ H} NMR spectra were recorded on
a Bruker Avance II-300 NMR spectrometer operating at 300 and 57.24 MHz, respectively.
Chemical shifts are relative to internal chloroform peak (δ 7.26 for 1H) and external Me2Se
1
for 77Se{ H} (secondary reference Ph2Se2 in CDCl3, δ 463 ppm). TG curves were recorded
on a Setsys Evolution 1750 instrument at a heating rate of 5ºC/min under flowing argon
atmosphere. Mass spectra were recorded in an MS-500 Ion Trap (IT) Varian mass spec-
trometer at Sophisticated Analytical Instrumentation Facility (SAIF), Indian Institute of
Technology-Bombay, Mumbai. Powder XRD patterns were recorded on a Philips PW1820
using Cu-Kα radiation.
Single crystal X-ray data of [Pd2(μ-Epy)2(Me2NCH2C6H4–C,N)2] (E = S or Se)
were collected on a Rigaku AFC 75 diffractometer using graphite monochromated Mo- Kα
(λ = 0.71069 Å) radiation so that θmax = 27.5 ◦. Crystallographic data, together with data
collection and refinement details are given in Table 3. All the data were corrected for Lorentz
and polarization effects. The structures were solved by direct methods28 and expanded using
Fourier technique.29 The nonhydrogen atoms were refined anisotropically and fitted with
hydrogen atoms in their calculated positions. All calculations were performed using crystal
structure crystallographic software package.30,31 Molecular structures were drawn using
ORTEP.32
Synthesis
Synthesis of [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2](2a). The complex was pre-
pared by a method different from the one reported by Deeming13. To a dichloromethane solu-
tion (15 mL) of [Pd(μ-Cl)(Me2NCH2C6H4–C,N)]2 (208 mg, 0.38 mmol), solid [Pb(Spy)2]
(167 mg, 0.39 mmol) was added and the reactants were stirred for 24 h. The contents were

1458
S. KOLAY ET AL.
Table 3 Crystal data and structure refinement details for [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2] and [Pd2(μ-
Sepy)2(Me2NCH2C6H4–C,N)2]
[Pd2(μ-Spy)2
[Pd2(μ-Sepy)2
(Me2NCH2C6H4–C,N)2]
(Me2NCH2C6H4–C,N)2]
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
Unit cell dimensions
a (Å)
C28H32N4Pd2S2
701.56
C28H32N4Pd2Se2
795.30
0.40 × 0.20 × 0.05
Monoclinic
C2/c
0.20 × 0.20 × 0.20
Triclinic
P1
10.333(3)
11.294(10)
13.794(6)
70.62(5)
72.560(17)
79.50(5)
16.131(9)
9.812(8)
18.867(11)
—
110.03(5)
—
2806(3)
b (Å)
c (Å)
α (◦)
β (◦)
γ (◦)
Volume (Å3)
1442.6(14)
1.615
Dcalc (g cm−-1
Z
)
1.883
4
2
μ (mm−1) / F(000)
θ range of data collection( ◦)
Index ranges
1.415 / 704
2.51–27.61
−13 ≤ h ≤ 7
−14 ≤ k ≤ 14
−17 ≤ l ≤ 17
6583 / 3231
6583 / 0 / 323
0.0551, 0.1081
0.1760, 0.1455
0.973
3.901 / 1552
2.53–27.50
−11 ≤ h ≤ 20
−12 ≤ k ≤ 7
−24 ≤ l ≤ 23
3217 / 1291
3217 / 0 / 165
0.0600, 0.1002
0.2326, 0.1407
0.929
Reflection collected / unique
Data/restraints/parameters
Final R1, ωR2 indices
R1, ωR2 (all data)
Goodness of fit on F2
Largest difference in peak
0.957, −0.957
0.844, −1.555
and hole (e A ◦
)
-3
passed through a Celite column. The clear filtrate was concentrated. To this hexane was
added, whereupon a yellow precipitate was formed, which was washed with diethyl ether
and recrystallized from dichloromethane containing few drops of hexane at 0–5 ◦C as yel-
low crystals (yield 176 mg; (66%), m.p.: >195 ◦C (dec). Anal. Calcd. for C28H32N4Pd2S2
: C, 47.9; H, 4.6; N, 8.0; S, 9.1. Found: C, 48.0; H, 4.7; N, 7.9; S, 8.9 %. Mass: m/z: 591
(M·+-Spy,). UV-Vis at λmax: 276, 337 nm. 1H NMR (CDCl3) δ: 2.39, 2.55 (each s, NMe2);
2.84–3.10 (AB pattern CH2N); 6.65–6.69 (m), 6.91 (br, C6H4); 6.99 (t, J = 6.6 Hz, CH–5),
7.30 (d, 7.5Hz, CH–4), 7.66 (d, J = 7.5 Hz, CH–3), 8.60 (d, J = 6Hz, CH–6) (Spy).
Synthesis of [Pd2(μ-Sepy)2(Me2NCH2C6H4–C,N)2](2b). To a toluene solu-
tion (20 mL) of NaSepy, prepared in situ by reduction of py2Se2 (115 mg, 0.37 mmol)
with methanolic NaBH4 (0.03 g, 0.79 mmol), [Pd(μ-Cl)(Me2NCH2C6H4–C,N)]2 (200 mg,
0.36 mmol) dissolved in toluene (10 mL) was added and the reaction mixture was stirred
for 2 h. The reaction mixture was evaporated under vacuum. The complex was extracted
with toluene and the solution was passed through Celite. The clear filtrate was concentrated
under reduced pressure. The residue was washed with diethyl ether and recrystallized from
dichloromethane-hexane mixture to give yellowish brown crystals (yield 225 mg; 78%),
m.p.: 193 ◦C (dec.). Anal. Calcd. for C28H32N4Pd2Se2: C, 42.3; H, 4.0; N, 7.0. Found: C,
42.2; H, 4.1; N, 7.2. Mass: m/z: 638 (M+ - Sepy); 504 (M+ - (N,N-dimethylbenzylamine

BINUCLEAR ORTHOMETALATED N,N-DIMETHYLBENZYLAMINE COMPLEXES 1459
1
+ Sepy)). UV-Vis at λmax: 275, 287, 330 nm. H NMR (500 MHz) (CDCl3) δ: (at room
temperature) 2.53 (s, NMe2), 2.97 (s), 3.13-3.37 (AB pattern) (NCH2), 6.68 (br) 6.76◦(t, J
= 6 Hz), 6.87 (m), 6.94 (m), 7. 45 (d, 8 Hz), 7.69 (br), 8.73 (d, J = 5 Hz); (at −30 C):
2.49, 2.52 (each s, NMe2), 2.97 (s) 3.05–3.14 (AB pattern) (NCH2), 6.68 (t, 1H, C6H4),
6.81 (t, 6.5 Hz,1H, C5H4N), 6.89 (t, 4.5 Hz, 2H, C6H4), 6.98 (t,7 Hz, 1H, C5H4N), 7.46 (d,
1
8 Hz, 1H, C5H4N), 7.75 (t,5 Hz, 1H, C6H4), 8.73 (d, 5Hz, 1H, C5H4N); 77Se{ H} NMR
(CDCl3) δ: 311 ppm.
Synthesis of [Pd2(μ-Cl)(μ-SPh)(Me2NCH2C6H4–C,N)2] (3a). To a toluene so-
lution (20 mL) of [Pd(μ-Cl)(Me2NCH2C6H4–C,N)]2 (300 mg, 0.54 mmol), PhSH (120 mg,
1.09 mmol) in toluene (5 mL) was added. After stirring for 5 min, Et3N (151 μL, 1.0 mmol)
was added and the whole reaction mixture was further stirred for 2 h. The contents were
passed through a Celite column and the clear filtrate was shaken first with distilled water
(1 × 10 mL) and then with aqueous NaCl solution (2 × 5 mL) in a separating funnel and, in
both the cases, organic fraction was collected. The organic fraction was stored over anhy-
drous Na2SO4. The clear solution was decanted and passed through Celite. The filtrate was
concentrated to 5 mL and the title complex was precipitated by adding hexane, which was
filtered and washed with diethyl ether and dried under vacuum. The complex was recrys-
tallized as a yellow crystalline solid from dichloromethane containing few drops of hexane
at 0–5 ◦C. Yield: 253 mg (74 %), m.p. 185 ◦C (dec.). Anal. Calcd. for C24H29ClN2Pd2S: C,
46.0; H, 4.7; N, 4.5; S, 5.1. Found: C, 45.9; H, 4.6; N, 4.6; S, 4.9 %. Mass: m/z: 626 (M+);
590 (M - Cl·). UV-Vis : λmax: 282, 339 nm. 1H NMR (CDCl3) δ: 2.77 (s, 12H, NMe2); 3.89
(s, 4H, CH2 ); 6.94–6.97 (m), 7.13 (m) (SPh); 7.60–7.63 (m),8.15–8.18 (m) (C6H4).
Synthesis of [Pd2(μ-Cl)(μ-SMes)(Me2NCH2C6H4–C,N)2] (3b). To
a
dichloromethane solution (15 mL) of [Pd(μ-Cl)(Me2NCH2C6H4–C,N)]2 (260 mg,
0.47 mmol), solid [Pb(SMes)2] (240 mg, 0.47 mmol) was added with stirring. The yellow
solution turned orange with appearance of a white precipitate. The reaction mixture was
stirred for 2 h and the solution was passed through a Celite column. The clear filtrate
was concentrated and the complex was precipitated by adding hexane. The precipitate
was washed with diethyl ether until the color of the washings became colorless. The
complex was crystallized from dichloromethane containing few drops of hexane at 0–5 ◦C
whereupon orange crystals were separated (yield 187 mg; 59%), m.p.: 166 ◦C (dec). Anal.
Calcd. for C27H35ClN2Pd2S: C, 48.5; H, 5.3; N, 4.2; S, 4.8. Found: C, 48.7; H, 5.2; N,
4.3; S, 4.5%. Mass: m/z: 668 (M+); 632 (M+-Cl) ; 517 (M+- SMes). UV-Vis at λmax: 279,
341 nm. 1H NMR (CDCl3) δ: 2.16 (s, 3H, 4-Me); 2.71 (s, 12H, NMe2); 3.14 (s, 6H ,2,6-Me);
3.85 (s, 4H, -CH2-); 6.44(s); 6.47 (s) (C6H2Me3); 6.54–6.60 (m); 6.79–6.82 (m) (C6H4).
Synthesis of [Pd2(μ-SePh)2(Me2NCH2C6H4–C,N)2] (4a). To a toluene solu-
tion (20 mL) of NaSePh, prepared in situ by reduction of Ph2Se2 (113 mg, 0.36 mmol)
with methanolic NaBH4 (30 mg, 0.79 mmol), [Pd(μ-Cl)(Me2NCH2C6H4–C,N)]2 (200 mg,
0.36 mmol) dissolved in 20 mL toluene was added and stirred for 2 h. The solvents were
evaporated under reduced pressure and the residue was extracted with benzene. The solution
was passed through Celite, concentrated and precipitated by adding hexane. The precipi-
tate was washed with diethyl ether and recrystallized from benzene/hexane mixture as red
crystals, (yield: 174 mg (61%), m.p. 158 ◦C (dec)). Anal. Calcd. for C30H34N2Pd2Se2: C,
45.4; H, 4.3; N, 3.5. Found: C, 45.1; H, 4.3; N, 3.2%. Mass: m/z: 793 (M+), 659 (M+-N,N-
1
dimethylbenzylamine), 637 (M+-SePh). UV-Vis : λmax : 276, 335 nm. H NMR (CDCl3)
δ: 2.76 (s, 12H, NMe2); 3.91 (s, 4H, -CH2 ); 6.89–6.97 (m), 7.12–7.15 (m), 7.63 (d, J =
1
6.6 Hz); 8.81 (d, d, 1.8, 7.8 Hz) (Ph + C6H4). 77Se { H} NMR (CDCl3) δ: 181 ppm.

1460
S. KOLAY ET AL.
Synthesis of [Pd2(μ-SeMes)2(Me2NCH2C6H4–C,N)2] (4b). Prepared similar
to reported method.4 (Characterization details are given in supplementary information).
Figure S13 shows the 77Se NMR spectrum of 4b.
SUPPLEMENTARY DATA
The full crystallographic data were deposited in the form of CIF files at
the Cambridge Structural Database (CCDC-Nos. 870373 and 870374 for [Pd2(μ-
Sepy)2(Me2NCH2C6H4–C,N)2](2b) and [Pd2(μ-Spy)2(Me2NCH2C6H4–C,N)2](2a), re-
spectively) and are available freely on request citing the deposition number from the website:
www.ccdc.cam.ac.uk/conts/retrieving.html.
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