Synthesis and structure of dichloropalladium(II) complexes of heteroleptic N,S- and N,Se-donor ligands based on the 2-organochalcogenomethylpyridine motif, and Mizoroki-Heck catalysis mediated by complexes of N,S-donor ligands

Article abstract of DOI:10.1016/j.ica.2009.10.002

Ligands containing the 2-organochalcogenomethylpyridine motif with substituents in the 4- or 6-position of the pyridyl ring, R⁴,R⁶-pyCH₂ER¹ [R⁴ = R⁶ = H, ER¹ = SMe (1), SeMe (2), SPh (6), SePh (7); R⁴ = Me, R⁶ = H, ER¹ = SMe (3), SPh (8), SePh (9); R⁴ = H, R⁶ = Me, ER¹ = SMe (4), SPh (10), SePh (11); R⁴ = H, R⁶ = Ph, ER¹ = SMe (5), SPh (12), SePh (13)] are obtained on the reaction of R⁴,R⁶-pyMe with LiBuⁿ followed by R¹EER¹. On reaction with PdCl₂(NCMe)₂, the ligands with a 6-phenyl substituent form cyclopalladated species PdCl{6-(o-C₆H₄)pyCH₂ER¹-C,N,E} (5a, 12a, 13a) with the structure of 13a (ER¹ = SePh) confirmed by X-ray crystallography; other ligands form complexes of stoichiometry PdCl₂(R⁴,R⁶-pyCH₂ER¹). Complexes with R⁶ = H are monomeric with N,E-bidentate configurations, confirmed by structural analysis for 3a (R⁴ = Me, ER¹ = SMe), 7a (R⁴ = H, ER¹ = SePh) and 9a (R⁴ = Me, ER¹ = SePh). Two of the 6-methyl substituted complexes examined by X-ray crystallography are oligomeric with trans-PdCl₂(N,E) motifs and bridging ligands, trimeric [PdCl₂(μ-6-MepyCH₂SPh-N,S)]₃ (10a) and dimeric [PdCl₂(μ-6-MepyCH₂SePh-N,Se)]₂ (11a). This behaviour is attributed to avoidance of the Me···Cl interaction that would occur in the cis-bidentate configuration if the pyridyl plane had the same orientation with respect to the coordination plane as observed for 3a, 7a and 9a [dihedral angles 8.0(2)-16.8(2)°]. When examined as precatalysts for the Mizoroki-Heck reaction of n-butyl acrylate with aryl halides in N,N-dimethylacetamide at 120 °C, the complexes exhibit the anticipated trends in yield (ArI > ArBr > ArCl, higher yield for electron withdrawing substituents in 4-RC₆H₄Br and 4-RC₆H₄Cl). The most active precatalysts are PdCl₂(R⁴-pyCH₂SMe-N,S) (R = H (1a), Me (3a)); complexes of the selenium containing ligands exhibit very low activity. For closely related ligands, the changes SMe to SPh, 6-H to 6-Me, and 6-H to 6-Ph lead to lower activity, consistent with involvement of both the pyridyl and chalcogen donors in reactions involving aryl bromides. The precatalyst PdCl₂(pyCH₂SMe-N,S) (1a) exhibits higher activity for the reaction of aryl chlorides in Buⁿ₄NCl at 120 °C as a solvent under non-aqueous ionic liquid (NAIL) conditions. Crown Copyright

Full text of DOI:10.1016/j.ica.2009.10.002

Inorganica Chimica Acta 363 (2010) 77–87
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis and structure of dichloropalladium(II) complexes of heteroleptic
N,S- and N,Se-donor ligands based on the 2-organochalcogenomethylpyridine motif,
and Mizoroki–Heck catalysis mediated by complexes of N,S-donor ligands
a,
a
b
a
Roderick C. Jones a, , Allan J. Canty , Michael G. Gardiner , Brian W. Skelton , Vicki-Anne Tolhurst ,
*
*
Allan H. White b
a School of Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
b Chemistry M313, University of Western Australia, Crawley, WA 6009, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Ligands containing the 2-organochalcogenomethylpyridine motif with substituents in the 4- or 6-
position of the pyridyl ring, R4,R6-pyCH2ER1 [R4 = R6 = H, ER1 = SMe (1), SeMe (2), SPh (6), SePh (7);
Received 29 September 2009
Accepted 2 October 2009
Available online 8 October 2009
R
R
4 = Me, R6 = H, ER1 = SMe (3), SPh (8), SePh (9); R4 = H, R6 = Me, ER1 = SMe (4), SPh (10), SePh (11);
4 = H, R6 = Ph, ER1 = SMe (5), SPh (12), SePh (13)] are obtained on the reaction of R4,R6-pyMe with LiBun
followed by R1EER1. On reaction with PdCl2(NCMe)2, the ligands with a 6-phenyl substituent form cyclo-
palladated species PdCl{6-(o-C6H4)pyCH2ER1-C,N,E} (5a, 12a, 13a) with the structure of 13a (ER1 = SePh)
confirmed by X-ray crystallography; other ligands form complexes of stoichiometry PdCl2(R4,R6-
pyCH2ER1). Complexes with R6 = H are monomeric with N,E-bidentate configurations, confirmed by struc-
tural analysis for 3a (R4 = Me, ER1 = SMe), 7a (R4 = H, ER1 = SePh) and 9a (R4 = Me, ER1 = SePh). Two of the
6-methyl substituted complexes examined by X-ray crystallography are oligomeric with trans-PdCl2(N,E)
Keywords:
Palladium
Thiomethylpyridine
Heck
Mizoroki–Heck
Non-aqueous ionic liquid catalysis
NAILs
motifs and bridging ligands, trimeric [PdCl2(
l-6-MepyCH2SPh-N,S)]3 (10a) and dimeric [PdCl2
Dimeric complexes
Trimeric complexes
Nitrogen–sulfur ligands
Heteroleptic ligands
(
l
-6-MepyCH2SePh-N,Se)]2 (11a). This behaviour is attributed to avoidance of the MeꢀꢀꢀCl interaction that
would occur in the cis-bidentate configuration if the pyridyl plane had the same orientation with respect
to the coordination plane as observed for 3a, 7a and 9a [dihedral angles 8.0(2)–16.8(2)°]. When examined
as precatalysts for the Mizoroki–Heck reaction of n-butyl acrylate with aryl halides in N,N-dimethylacet-
amide at 120 °C, the complexes exhibit the anticipated trends in yield (ArI > ArBr > ArCl, higher yield for
electron withdrawing substituents in 4-RC6H4Br and 4-RC6H4Cl). The most active precatalysts are
PdCl2(R4-pyCH2SMe-N,S) (R = H (1a), Me (3a)); complexes of the selenium containing ligands exhibit very
low activity. For closely related ligands, the changes SMe to SPh, 6-H to 6-Me, and 6-H to 6-Ph lead to
lower activity, consistent with involvement of both the pyridyl and chalcogen donors in reactions involv-
ing aryl bromides. The precatalyst PdCl2(pyCH2SMe-N,S) (1a) exhibits higher activity for the reaction of
aryl chlorides in Bun4NCl at 120 °C as a solvent under non-aqueous ionic liquid (NAIL) conditions.
Crown Copyright Ó 2009 Published by Elsevier B.V. All rights reserved.
1. Introduction
coordination and organometallic chemistry [3,4], and palladium
catalysis for addition of diethylzinc to benzaldehyde [5a,b], allylic
Bidentate heteroleptic ligands containing donor groups with
widely different characteristics offer opportunities in catalysis
and stoichiometric synthesis, in particular the ability to both stabi-
lise intermediate species via chelation and to encourage reactivity
and low energy transition states via partial dissociation [1]. For
N,S-donors and the nickel triad, the most widely studied system in-
volves the 2-organothiomethylpyridine motif (I) [2–6], in particu-
lar by Canovese [3;4a–i,k–m,5c–e], including applications in
coordination chemistry [2,3], probing reaction mechanisms in
substitution [5a], trimerisation of dimethyl acetylene dicarboxyl-
ate [5c], and the stoichiometric synthesis of fluoranthenes [5d]
and 2,4-diene-6-ynes [5f].
R4
R6
N
ER1
I
R4,R6-pyCH2ER1
* Corresponding authors. Tel.: +61 3 6226 2162; fax: +61 3 6226 2858.
E-mail address: Allan.Canty@utas.edu.au (A.J. Canty).
0020-1693/$ - see front matter Crown Copyright Ó 2009 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.10.002

78
R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
We have reported preliminary investigations of the application of
2.2. Synthesis and characterisation of complexes
dichloropalladium(II) complexes of
I in Mizoroki–Heck (E = S,
R1 = Me, R6 = H, R4 = H [6a], p-BnOC6H4 [6b]; R1 = Ph, R4 = R6 = H
[6a]) and Suzuki–Miyaura catalysis [6b], including supported catal-
ysis on organic polymer beads and porous organic polymer mono-
Complexes were readily obtained on the reaction of
PdCl2(NCMe)2 with the above ligands in acetonitrile at room tem-
perature, followed by evaporation to low volume and addition of
diethyl ether. New complexes were obtained as yellow or orange
(13a) solids in 80–96% yield, and in the solid state have the formu-
lations shown in Eqs. (2)–(5) based on X-ray structural studies of
3a, 7a, 9a, 10a, 11a, 13a (see below), 6 [6a], microanalysis and sup-
portive 1H NMR spectra for 1 [6a], 2 [6a], 6a, 5a, 12a. Complex 4a
has microanalysis consistent with a 1:1 ratio of PdCl2:6-Me-
pyCH2SMe, but the structure is not assigned (see below).
lith in
a
microreactor flow-through system comprised of
a
capillary of internal diameter 250
lm [6b]. Related studies of
unsymmetrical bidentate (heteroleptic) systems in Mizoroki–Heck
catalysis appear to be limited to neutral P,O [7], P,S [8] and P,N [9]
and anionic-[N,O]ꢁ [10] ligands utilising donor atoms from both
groups 15 and 16, where these systems offer an alternative to less
stable phosphine ligands [11]. We report here the application of a
synthetic protocol for the facile synthesis of a range of 2-organoch-
alcogenomethylpyridine ligands (I), the synthesis of dichloropalla-
dium(II) complexes, cyclopalladated complexes of 6-phenyl
substituted ligands, structural studies of selected complexes, and
investigation of the complexes as precatalysts in Mizoroki–Heck
catalysis ((Eq. (1)) including for aryl chlorides under non-aqueous
ionic liquid (NAIL) conditions.
PdCl2ðNCMeÞ þ R4; R6-pyMe ! PdCl2ðR4; R6-pyCH ER1-N; EÞ
2
2
1—4;6—9
1a—3a;6a—9a
ð2Þ
ð3Þ
PdCl2ðNCMeÞ2 þ 6-MepyCH2SPh
10
! 1=3 ½PdCl2ð
l
-6-MepyCH2SPh-N; SÞꢂ3
10a
Ar—X þ CH2@CHR þ base ! ArCH@CHR þ ½baseHꢂX
ð1Þ
PdCl2ðNCMeÞ2 þ 6-MepyCH2SePh
11
! 1=2 ½PdCl2ð
l
-6-MepyCH2SePh-N; SeÞꢂ2
ð4Þ
2. Results and discussion
11a
2.1. Synthesis of ligands
PdCl2ðNCMeÞ þ 6-Ph-pyCH ER1
2
2
5;12;13
Ligands of general structure I are usually synthesised by reaction
of 2-halogenomethylpyridines with RSꢁ [2e,4a–c,e,i,6b,12–17]
although there is a report of the reaction of pyMe with lithium
diethylamide followed by selenium to give pyCH2Seꢁ and reaction
with MeI to give pyCH2SeMe [18], and reaction of 2-picolines with
! PdClf6-ðo-C6H4ÞpyCH ER1-C; N; Eg
ð5Þ
2
5a;12a;13a
The results of the single crystal X-ray studies are consistent
with the presence of neutral molecules as expected, mononuclear
except for 11a (binuclear) and 10a (trinuclear), a number being
solvated with MeNO2 or MeCN (Figs. 1–4, Tables 1 and 2). All are
devoid of crystallographic symmetry except the dimer of 11a
which is disposed about a crystallographic inversion centre, one
half of the dimer comprising the asymmetric unit of the structure.
In 7a and 9a (MeCN solvate form), a single monomer comprises the
asymmetric unit; 3a (MeNO2 solvate) and 9a (unsolvated form)
have two monomers; 13a has four; and 10a (MeNO2 solvate) has
one trimer in the asymmetric unit.
The molecular structures of 3a, 7a, 9a are similar, the palla-
dium atoms lying in four-coordinate distorted ‘square planar’
PdNECl2 environments, similar to those previously recorded in
6a ([PdCl2(pyCH2SPh-N,S)]) [6a] and [PdCl2(4-RpyCH2SMe-N,S)]
(R = 4HOC6H4, 4-BnOC6H4) [6b]. The former show the expected dif-
ference in Pd–S,Se distances, and in Pd–Cl trans to Pd–N,E (Table 1).
In consequence of the five-membered chelate ring constraints, the
coordination planes are distorted, with the nitrogen atoms lying
well out of plane, in conjunction with the pyridine ring planes
being tilted relative to the coordination planes. The chelate rings
are considerably puckered (Table 1), with rather wide divergences
in some of the angles about the chalcogen atoms. In 3a, the two
independent molecules pack as quasi-centrosymmetric pairs with
their ‘inversion images’ (Fig. 1b), the closest distances between
the coordination planes being between the metal atoms 3.781(1),
3.697(1) Å; similar packing in unsolvated 9a results in a much clo-
ser contact between the two independent molecules of the asym-
metric unit, Pd(1)ꢀꢀꢀPd(2) being 3.3651(7) Å; all planes are
oriented quasi-parallel to (1 1 0) (Fig. 1c). In the Se–Ph arrays here
and elsewhere the phenyl ring planes lie quasi-normal to their
coordination planes.
ꢁ
LiBun to give RpyCH2 followed by reaction with R1SSR1 to give 3-
MepyCH2SPh [19] and 1–3,4,6 (Scheme 1) [2e]. The latter approach
has been explored here as a general method because a wide range of
diorganodichalgogenides and substituted 2-picolines are commer-
cially available, although we obtained 6-PhpyMe by modification
of a reported synthesis [20]. This method allowed the synthesis of
new ligands (6-PhpyCH2SMe, 4-MepyCH2SPh, 6-PhpyCH2SPh, 4-
MepyCH2SePh, 6-PhpyCH2SePh) in good to high yield (51–85%)
except for 4-MepyCH2SPh (25%); the previously known ligands (6-
MepyCH2SPh [4b], pyCH2SeMe [13], pyCH2SePh [4e], 6-
MepyCH2SePh [4e]) were obtained in 32–92% yield (Scheme 1).
R4
N
R4
N
(i) LiBun
(ii) R1EER1
R6
Me
R6
ER1
R4,R6-pyMe
R4,R6-pyCH2ER1
1-13
1 pyCH2SMe
2 pyCH2SeMe
8
9
4-MepyCH2SPh
4-MepyCH2SePh
3 4-MepyCH2SMe
4 6-MepyCH2SMe
5 6-PhpyCH2SMe
6 pyCH2SPh
10 6-MepyCH2SPh
11 6-MepyCH2SePh
12 6-PhpyCH2SPh
13 6-PhpyCH2SePh
The cyclopalladated complex 13a (Fig. 2a) has longer Pd–Se ow-
ing to the trans-effect of Pd–C, and Pd–N is shorter in keeping with
its role as the central donor of a tridentate ligand. The pyridine ring
is now more closely aligned with the coordination plane (as is the
7 pyCH2SePh
Scheme 1. Synthesis of 2-organochalcogenomethylpyridines.

R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
79
Fig. 1. (a) (i) Projection of 3a (molecule 1) normal to the coordination plane; the other molecule is similar, as also are both forms of 9a; (ii) projection of 7a similarly. About
50% probability amplitude displacement envelopes are shown for the non-hydrogen atoms in this and the other figures; hydrogen atoms where shown have arbitrary radii of
0.1 Å. (b) Unit cell contents of 3a, projected down b, showing the packing of the two independent molecules as centrosymmetric pairs. (c) Unit cell contents of unsolvated 9a,
projected down [1 1 0].

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R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
Fig. 2. (a) Projection of molecule 1 of 13a, normal to the coordination plane (molecules 2–4 are similar). (b) Unit cell contents projected down c, showing the orientations of
the coordination planes and the planes of the pendant phenyl rings parallel and normal to the axis, respectively.
coordinated phenyl ring), with the puckering of the five-membered
ring containing the chalcogen diminished. The aggregate of these
planes is aligned quasi-parallel to the c-axis, the pendant (Seꢁ)phe-
nyl ring planes quasi-normal (Fig. 2b). Again close PdꢀꢀꢀPd distances
are found: Pd(1)ꢀꢀꢀPd(2) (x, 1 ꢁ y, ½ + z) 3.442(2); Pd(3)ꢀꢀꢀPd(4)
(x ꢁ ½, y ꢁ ½, z) 3.434(1) Å.
and the Cl2SeN plane tending towards the normal (88.5(1))°, one
of the chlorine atoms having a close contact to a methylene hydro-
ꢀ
gen atom (Cl(2)ꢀꢀꢀH(21B) (x, 1 ꢁ y, 1 ꢁ z) 2.67 Å (est.)). Alterna-
tively,
a view projected through the selenium and opposed
methylene carbon atom, both of which subtend similar angles
within the ten-membered metallocycle, portrays the array in terms
of a displaced/step structure (Fig. 3b). Pendant C6/C5N1Se2N2Pd2
dihedral angles are 55.8(2)°, 70.2(1)°; the palladium atom lies
0.190(6) Å out of the C5N plane. The PdꢀꢀꢀPd distance is 3.6539(8) Å.
Fig. 3 shows the dimer of 11a projected onto the plane gener-
ated by the pair of inversion-related SePdN struts; the pyridine
ring plane is inclined to it (interplanar dihedral angle 26.6(1)°)

R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
81
Fig. 3. Projections of the dimer of 11a, (a) normal to the (SePdN)2 plane, and (b)
illustrating the conformation of the ring and trans-PdCl2 units aligned almost
parallel.
Fig. 4. Projection of the trimer of 10a, (a) normal to the Pd3 plane, and (b)
illustrating the conformation of the ring and trans-PdCl2 units aligned almost
parallel.
Compound 10a may be regarded as an extension of the dimer,
where presence of a further Cl2PdL unit into the macrocycle, results
in a fifteen-membered metallocycle, above the centre of which the
disordered solvent molecule lies (Fig. 4). There is ca. 20% disorder
in part of the ring, evidenced by refinement of fragments of Pd(3)
and associated Cl(31 and 32) and the adjoining S(2). Dihedral an-
gles of the C5N planes 1–3 to the Pd3 plane are 22.1(2)°, 28.2(2)°,
22.1(2)°, and of the pendant C6 planes 63.5(2)°, 56.0(2)°, 47.8(2)°;
the associated palladium atoms lie 0.16(1), 0.08(1), 0.18(1) Å out
of their C5N planes.
In view of these observations a structure has not been assigned
to the third complex containing a 6-methyl group, PdCl2(6-Me-
pyCH2SMe) (4a).
The complexes exhibit microanalyses consistent with formula-
tions revealed by X-ray structural analysis, i.e. 6-H and 6-Me sub-
stitution corresponding to PdCl2(L), and 6-Ph substitution
corresponding to PdCl(6-C6H4pyCH2ER1-C,N,E). LSIMS mass spectra
show [MꢁCl]+ for all complexes except the trimer (no ions ob-
served) and the dimer (showing breakdown to monomer,
½[(MꢁCl)]+).
New complexes with a 6-hydrogen substituent give 1H NMR
spectra for (CD3)2SO solutions similar to that reported for 1a, 2a,
and 6a [6a], in particular methylene resonances (AB spin system
for 3a, 7a–9a) exhibiting coalescence temperatures 72–94 °C, com-
pared with 82–95 °C for 1a, 2a, and 6a, as a result of facile flipping
of the chelate ring together with inversion at the chalcogen as dis-
cussed in detail elsewhere for 1a, 2a and 6a [6a].
The trimeric (10a) and dimeric (11a) complexes, the complex
with a 6-methyl substituent whose structure in the solid state
has not been determined [PdCl2(6-MepyCH2SMe)] (4a), and the
cyclopalladated complexes (5a, 12a, 13a) have low solubility. The
complexes exhibited broad NMR signals in (CD3)2SO that were dif-
ficult to interpret, e.g. PdCl2(6-MepyCH2SMe) 4a showed a broad
methylene resonance without evidence of a coalescence process
in variable temperature spectra. Spectra of the other 6-substituted
complexes are consistent with the presence of conformers/equilib-
ria, e.g. hemilabile behaviour and solvent coordination. They
exhibited two broad methylene resonances in the ratio 60:40
(10a), 70:30 (11a) and 1:1 for the cyclopalladated species (5a,

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R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
Table 1
1
Selected bond distances and angles for PdCl2(4-MepyCH2SMe) (3aꢀ 4MeNO2), PdCl2(pyCH2SePh) (7a) and PdCl2(4-MepyCH2SePh) (9a) (unsolvated, MeCN solvated).
(3a) (mols. 1,2)
(7a)
(9a) (unsolvated; mols. 1,2)
(9aꢀMeCN)
Bond distances (Å)
Pd–N(1)
2.041(4), 2.049(5)
2.043(3)
2.062(4), 2.069(4)
2.055(5)
Pd–E(1)
Pd–Cl(1)
Pd–Cl(2)
2.2564(15), 2.2498(18)
2.3268(16), 2.3205(19)
2.2880(16), 2.277(2)
2.3537(7)
2.3257(11)
2.2844(11)
2.3647(7), 2.3537(7)
2.3516(14), 2.3352(14)
2.2914(17), 2.2942(16)
2.3541(8)
2.3269(18)
2.2870(19)
Bond angles (°)
N(1)–Pd–E(1)
85.40(13), 85.22(15)
94.26(13), 94.13(15)
173.58(13), 173.81(16)
177.95(7), 178.87(8)
89.04(6), 88.91(8)
91.40(6), 91.77(8)
97.2(18), 96.5(2)
86.81(9)
94.88(9)
172.70(9)
173.52(3)
88.14(4)
90.71(4)
95.1(1)
86.36(12), 86.64(12)
96.99(13), 95.36(13)
170.91(13), 172.74(13)
176.57(4), 174.59(4)
86.87(4), 86.14(4)
89.71(5), 91.90(5)
97.6(17), 93.39(16)
100.3(17), 98.25(16)
99.2(3), 101.1(2)
86.66(15)
94.62(16)
174.51(16)
178.33(6)
87.85(5)
90.87(7)
94.1(2)
N(1)–Pd–Cl(1)
N(1)–Pd–Cl(2)
E(1)–Pd–Cl(1)
E(1)–Pd–Cl(2)
Cl(1)–Pd–Cl(2)
Pd–E(1)–C(H2)
Pd–E(1)–C(H3,Ar)
C(H2)–E(1)–C(H3,Ar)
103.7(2), 104.4(3)
100.7(3), 101.6(4)
105.3(1)
101.4(2)
99.3(2)
102.0(3)
Chelate ring torsion angles (°)
E–Pd–N–C
Pd–N–C–C
N–C–C–E
C–C–E–Pd
C–E–Pd–N
Me/Ar–E–Pd–N
Me/Ar–E–C–C
ꢁ10.7(4), 13.1(5)
ꢁ9.4(7), 7.2(8)
11.0(2)
1.1(4)
ꢁ2.6(4), ꢁ11.4(4)
10.0(7), ꢁ7.9(6)
ꢁ12.5(7), 28.3(6)
8.5(4), ꢁ30.1(4)
ꢁ3.2(2), 20.0(2)
97.6(2), ꢁ81.7(2)
ꢁ93.3(4), 69.0(4),
12.6(5)
2.6(8)
30.4(6), ꢁ30.3(8)
ꢁ32.5(4), 34.2(5)
21.7(2), ꢁ23.3(3)
ꢁ81.2(3), 80.4(4)
73.0(5), ꢁ71.9(6)
ꢁ16.4(2)
20.0(3)
ꢁ14.9(1)
88.5(2)
ꢁ87.2(2)
ꢁ21.0(8)
24.8(5)
ꢁ17.8(3)
85.0(3)
ꢁ75.7(6)
Interplanar dihedral angles (°) and out-of-plane deviations (dÅ)
C5N/Cl2EN
16.8(2), 16.7(2)
16.8(1)
11.2(1), 8.0(2)
12.2(2)
C6/Cl2EN
dPd/C5N
ꢁ
79.1(1)
88.0(2), 86.1(2)
87.3(3)
0.176(8), 0.091(9)
0.025(1), 0.009(1)
0.149(6), 0.077(7)
ꢁ0.155(2), ꢁ0.009(2)
ꢁ0.015(2), ꢁ0.012(3)
0.014(2), 0.017(4)
0.008(5)
0.100(1)
0.337(4)
ꢁ0.032(1)
ꢁ0.029(1)
0.033(1)
0.226(8), 0.050(8)
ꢁ0.019(8), 0.094(1)
0.169(5), 0.183(5)
ꢁ0.007(1), ꢁ0.007(1)
ꢁ0.014(2), ꢁ0.014(2)
0.013(2), 0.012(2)
0.013(9)
0.019(1)
0.032(6)
ꢁ0.001(1)
ꢁ0.004(3)
0.004(3)
dPd/Cl2EN
dN/Cl2EN
dE/Cl2EN
dCl(1)/Cl2EN
dCl(2)/Cl2EN
Table 2
Selected bond distances and angles for [PdCl2(
l
-6-MepyCH2SPh-N,S)]3ꢀMeNO2 (10a), [PdCl2(l-6-MepyCH2SePh-N,Se)]2 (11a) and [PdCl{6-(o-C6H4)pyCH2SePh-C,N,S}] (13a).
a
(10aꢀMeNO2) (frags. 1–3)
(11a)
(13a)b (mols. 1–4)
Bond distances (Å)
Pd–N(1)
Pd–E(1)
Pd–C(66)
Pd–Cl(1)
Pd–Cl(2)
2.080(17), 2.053(17), 2.054(19)
2.282(5), 2.277(5), 2.280(7)
2.051(3)
2.4057(10)
2.006(5), 2.010(5), 2.005(5), 2.014(5)
2.5033(13), 2.5201(10), 2.5081(10), 2.5434(11)
1.989(6), 1.989(6), 1.986(6), 1.986(6)
2.302(2), 2.312(2), 2.323(3), 2.311(2)
2.297(5), 2.269(7), 2.340(8)
2.287(7), 2.290(8), 2.304(10)
2.3200(11)
2.3084(11)
Bond angles (°)
N(1)–Pd–E(1)
N(1)–Pd–Cl(1)
N(1)–Pd–Cl(2)
N(1)–Pd–C(66)
E(1)–Pd–Cl(1)
E(1)–Pd–Cl(2)
E(1)–Pd–C(66)
Cl(1)–Pd–Cl(2)
Cl(1)–Pd–C(66)
Pd–E(1)–C(H2)
Pd–E(1)–C(Ar)
C(H2)–E(1)–C(Ar)
176.4(5), 176.3(5), 173.5(6)
91.3(5), 88.5(5), 89.1(6)
87.1(5), 91.0(5), 89.7(6)
176.82(9)
90.24(10)
86.87(10)
86.58(14), 85.42(13), 86.20(14), 84.36(14)
178.53(14), 176.56(14), 177.06(14), 177.01(15)
82.0(2), 81.7(2), 81.5(2), 82.7(2)
94.89(5), 97.94(5), 94.74(5), 98.59(5)
85.85(19), 95.2(2), 96.6(3)
95.8(2), 85.4(2), 84.9(3)
86.59(4)
96.31(4)
166.4(2), 165.1(2), 165.5(2), 163.4(2)
177.7(2), 178.4(2), 176.3(3)
174.58(4)
96.6(2), 94.9(2), 97.2(2), 94.5(2)
91.7(2), 97.2(2), 97.9(2), 90.4(2)
97.0(2), 91.2(2), 91.2(2), 94.4(2)
100.8(3), 99.3(3), 99.6(2), 97.8(3)
109.7(4), 110.8(2), 109.5(2)
106.9(3), 104.5(2), 107.5(2)
98.9(4), 103.4(3), 99.0(3)
108.8(1)
101.6(1)
96.5(2)
a
Three independent Pd environments; the third has disorder, data for the major component being shown.
Four molecules in the asymmetric unit.
b
12a, 13a) where the lower relative intensity resonances for 10a
and 11a, and one of the resonances for the cyclopalladated com-
plexes are close to values for the free ligands. The ratio of these res-
onances alter on warming. For the more NMR amenable complex
5a containing an SMe group, spectra at 85 °C showed two ‘aryl
environments’, two SMe resonances, and two broad methylene res-
onances, all in 65:35 ratio. For both SMe and CH2, the resonances of
lower relative intensity are within ca. 0.05 ppm of the value for the
free ligand, consistent with presence of thiomethyl dissociation
opposite the high trans effect aryl group leading to presence of,
for example, species that may contain solvent coordination or
chloro bridges.
2.3. Catalysis
For the Mizoroki–Heck reaction, the precise nature of species in
the catalytic cycle is not fully resolved [21], but at temperatures
near or above ca. 120 °C decomposition of precatalysts is assumed

R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
83
Table 4
to occur to form nanoparticles which act as sources of Pd(0) species
that participate in homogeneous catalysis [10b,21i–l,22,23],
although a recent report suggests that the catalysis reaction can
proceed on the surface of nanoparticles [21l,23b]. Palladium may
also be released as Pd(II) via oxidative addition at the surface
[21i,k,l,23e]. It is feasible that neutral ligands may have roles in
stabilising nanoparticles [21l], together with quaternary ammo-
nium salts [10b,21k,l,22,23b–d], and in releasing Pd(0) atoms from
the surface of nanoparticles. For aryl iodides there is evidence for
the absence of a requirement for neutral ligand coordination in
Mizoroki–Heck catalysis [21b,e,h,i,24]. When aryl bromides and
aryl chlorides are used as substrates, the rate determining step is
generally considered to be oxidative addition to Pd0Ln, or [Pd0LnX]ꢁ
[21d] and, for bidentate ligands in the presence of a high concen-
tration of potentially coordinating anions, hemilabile behaviour is
anticipated to allow the alkene insertion step on reaction of
PdIIXAr(LꢃL) with alkene [21b,m,25]. In view of these consider-
ations, investigation of R4,R6-pyCH2ER1 complexes as precatalysts
was generally confined to aryl bromides and chlorides, conducted
at 120 °C and with presence of sodium formate [26] to encourage
reduction to Pd(0); Na2CO3 as a base [21c,e,27a]; Bun4NCl princi-
pally as a phase transfer reagent [27] and stabiliser of nanoparti-
cles, but also providing high [Clꢁ]/[Pd] ratio to encourage
chloride coordination and thus likely involvement of hemilabile
behaviour by the neutral ligand [21b,25]; and anhydrous N,N-
dimethylacetamide (DMAc) as a commonly used polar solvent
[9c,1oa,d,11d,e,21c,e,g,m].
Catalytic data for the Heck reaction of 4-halogenoarenes (RC6H4X) and n-butyl
acrylate, using PdCl2(pyCH2SMe) (1a) as the precatalyst.a
Entry
X
R
Mol% Pd
Yield (%)
1
2
3
4
5
6
7
8
I
I
I
I
Br
Br
Br
Br
Cl
Cl
Cl
Cl
COMe
H
Me
OMe
COMe
H
10ꢁ4
10ꢁ4
10ꢁ4
10ꢁ4
10ꢁ4
10ꢁ4
10ꢁ3
10ꢁ2
1
>99
>99
99
97
>99
36
Me
43
58
OMe
COMe
COMe
H
9
13
10
11
12
1
1
1
>99a
<1
H
87a
Experimental conditions: As for Table 3 except for Bun4NCl (2.48 g) was used and
a
DMAc was omitted.
ilarly, lower yields on 6-Me substitution implies coordination of
the pyridyl donor, consistent with anticipated difficulty of coordi-
nation of the 6-Me-pyridyl donor indicated by solid state structural
analyses. Activities observed for the cyclopalladated precatalysts,
5a (TON 670) and 12a (TON 950) at 0.1 mol%, are consistent with
reports for
(TON 900-2000) [28].
a
related species PdCl{pyC(Cl)CCH2CH2SBut-N,C,S}
The most active precatalyst (1a) was examined with a range of
aryl halides (Eq. (7), Table 4), including under non-aqueous ionic
liquid (NAIL) conditions similar to earlier reports [29] (including
use of Na2CO3, and NaO2CH) [29c] for the least reactive reagents
(aryl chlorides, Entries 10 and 12). In general terms, the trends
are as expected [21] for Mizoroki–Heck catalysis: Ar–I (Entries 1–
4) > Ar–Br (5–8) > Ar–Cl (9,11), and the electron-withdrawing sub-
stituent (COMe) results in higher yield for aryl bromides (5 > 6)
and aryl chlorides (9 > 11) including under NAIL conditions for aryl
chlorides (10 > 12). Presence of electron-donating substituents
(Me, OMe) results in lower yield (6 > 7, 8 where 7 and 8 are at high-
er mol% Pd), and NAIL conditions resulted in much improved yields
for aryl chlorides (10 > 9, 12 > 11).
4-MeC6H4-Br þ CH2@CHCO2Bun
! trans-ð4-MeC6H4ÞCH@CHCO2Bun
ð6Þ
Reactions of 4-bromotoluene with n-butyl acrylate were exam-
ined at 1 mol% palladium and, for those precatalysts showing high-
est activity, 0.1 mol%, and subsequently 0.01 mol% for the most
active precatalysts including aryl iodides for comparison (Eq. (6),
Table 3).
The most active precatalysts have a 6-H substituent and a thio-
methyl donor (1a, 3a), exhibiting essentially quantitative yield at
1–10ꢁ2 mol%; those containing an N,Se donor are inactive (2a, 7a,
9a, 11a), and very low activity is shown by the cyclopalladated
complex involving selenium (13a). The remaining complexes
(4a–6a, 8a, 12a) exhibit intermediate activity, with yields of 65–
85% at 0.1 mol%, except for the complex with a 6-Me substituent
and SPh donor (10a, 11%). Lower yields for selenium containing li-
gands, together with lower yields for –SPh than –SMe containing
ligands, imply that coordination of the chalcogen is involved. Sim-
4-RC6H4-X þ CH2@CHCO2Bun ! trans-ð4-RC6H4ÞCH@CHCO2Bun
ð7Þ
The trends discussed above, in particular those implicating
bidentate behaviour, are consistent with a major role for the li-
gands in the catalytic cycle for aryl bromides, and presumably
chlorides.
3. Conclusions
Table 3
Catalytic data for the Heck reaction of 4-bromotoluene and n-butyl acrylate.a
2-Organochalcogenomethylpyridine ligands are accessible in
mid-high yield from substituted 2-picolines, and dichloropalla-
dium(II) complexes are readily obtained in high yield on simple
addition reactions although phenyl-substitution in the 6-position
of pyridine leads to cyclopalladation reactions. Methyl-substitu-
tion in the 6-position results in oligomers involving trans-
PdCl2(N,E) units, assumed to relieve MeꢀꢀꢀCl steric interactions;
cis-coordination, as obtained in the absence of a substituent, may
be feasible in view of the reported structural analysis of
PdClMe(6-MepyCH2SBut-N,S) which has the chloro ligand cis to
the pyridyl donor [4d]. In this complex the pyridyl mean plane
forms a dihedral angle of 34.4° with the mean coordination plane
(PdCl2NS) [4d], significantly larger than 3a, 7a and 9a (8.0(2)–
16.8(2)°, see above), reflecting the effect of the MeꢀꢀꢀCl interaction.
Catalysis results implicate bidentate coordination in the rate
determining step for reactions of aryl bromides. The most success-
ful system is based on the readily accessible pyCH2SMe ligand, e.g.
Precatalyst
Mol% Pd
Yield (%)
1a
2a
3a
4a
5a
6a
7a
8a
PdCl2(pyCH2SMe)
PdCl2(pyCH2SeMe)
PdCl2(4-MepyCH2SMe)
PdCl2(6-MepyCH2SMe)
PdCl(6-C6H4pyCH2SMe)
PdCl2(pyCH2SPh)
1, 10ꢁ1, 10ꢁ2
>99, >99, >99
18
1
1, 10ꢁ1, 10ꢁ2
>99, >99, 92
97, 78
>99, 67
90, 74
ca. 0.5
83, 65
1
79, 11
0
>99, 85
32
1, 10ꢁ1
1, 10ꢁ1
1, 10ꢁ1
1
PdCl2(pyCH2SePh)
PdCl2(4-MepyCH2SPh)
PdCl2(4-MepyCH2SePh)
PdCl2(6-MepyCH2SPh)
PdCl2(6-MepyCH2SePh)
PdCl{6-(o-C6H4)pyCH2SPh}
PdCl{6-(o-C6H4}pyCH2SePh}
1, 10ꢁ1
1
9a
10a
11a
12a
13a
1, 10ꢁ1
1
1, 10ꢁ1
1
a
Experimental conditions: 4-Bromotoluene (1.5 mmol), n-butyl acrylate
(4.0 mmol), Na2CO3 (3.0 mmol), Bun4NCl (2.25 mmol), NaO2CH (1.65 mmol), in
DMAc at 120 °C for 48 h. Yields were determined by GC-FID using diphenyl ether as
a standard.

84
R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
exhibiting TONs for p-MeOC6H4Br ca. 5845 at 120 °C for 48 h, sim-
ilar to that of the N,O-bidentate precatalyst bis(quinoline-8-car-
boxylato)palladium(II) assessed as fairly high (TON 7300 at
130 °C for 30 h) [10e]; a higher yield was obtained for aryl chlo-
rides under non-aqueous ionic liquid conditions. Thus, ligands of
the type examined here offer an alternative to phosphines as
ligands.
CH2), 2.15 (3H, s, CH3). 13C{1H} NMR: d 158.8 (2-py), 156.7 (6-
py), 141.4 (1-Ph), 138.3 (4-py), 129.5 (4-Ph), 129.0 (3,5-Ph),
127.4 (2,6-Ph), 121.7 (3-py), 119.3 (5-py), 39.8H(2) 15.6 (CH3). Anal.
Calc.: C, 72.48; H, 5.99; N, 6.52; S, 15.01. Found: C, 72.52; H, 6.09; N,
6.51; S, 14.89%. EI m/z 215 [M]+, [12C13H1314N32S 215].
4.1.3. 2-Methylselenomethylpyridine 2; 6-phenyl-2-
phenylthiomethylpyridine (12); 6-phenyl-2-
phenylselenomethylpyridine (13)
4. Experimental
These ligands were prepared in a similar manner to 5 and, and
were purified by passage through a silica plug (10% toluene in hex-
anes) to remove contamination by diorganodichalcogenide to give
products as a yellow oil (2, 92%; 12, 76%) and pale yellow oil (13,
85%).
All solvents were dried and distilled by conventional methods
prior to use; tetrakis(triphenylphosphine)palladium was prepared
as reported [30], 2-bromo-6-methylpyridine was purchased (Lan-
caster) and other reagents (Aldrich) were used as received. NMR
spectra were recorded on a Varian Mercury Plus 300 spectrometer
(1H, 299.9 MHz; 13C{1H}, 75.4 MHz) in CDCl3 (6-MepyMe and li-
gands) or (CD3)2SO (complexes) at 20 °C unless otherwise noted,
and chemical shifts are reported in ppm relative to TMS. Assign-
ments were facilitated by gHMBC, gHMQC and gCOSY techniques.
Electron Ionisation mass spectra were obtained using a Kratos ISQ
spectrometer with a liquid matrix of nitrobenzyl alcohol using
10 kV Cs ions and a 5.3 kV accelerating voltage.
2: 1H NMR: d 8.51 (1H, d, J = 7.8 Hz, 6-py), 7.64 (1H, m, 4-py),
7.29 (1H, d, J = 7.8 Hz, 3-py), 7.14 (1H, m, 5-py), 3.86 (2H, s, CH2),
1.99 (3H, s, CH3); 13C{1H} NMR: d 159.8 (2-py), 149.0 (6-py),
137.3 (4-py), 123.4 (3-py), 121.9 (5-py), 29.8 (CH2), 4.8 (CH3). Anal.
Calc.: C, 45.38; H, 4.79; N, 7.60. Found: C, 45.17; H, 4.87; N, 7.53%.
EI m/z 186 [M]+, [12C7H914N80Se 186].
12: 1H NMR: d 7.95 (2H, dd, J = 6.9, 0.9 Hz, 2,6-Ph), 7.68 (1H, m,
4-py), 7.57 (1H, d, 5-py), 7.42 (5H, m, 3,4,5-Ph and 2,6-SPh), 7.26
(4H, m, 3-py and 3,5-SPh), 4.35 (2H, s, CH2); 13C{1H} NMR: d
157.8 (2-py), 156.9 (6-py), 138.0 (4-py), 135.9 (1-SPh), 132.8
(2,6-SPh), 129.8 (3,5-SPh), 129.4 (4-Ph), 129.1 (3,5-Ph), 128.0 (4-
SPh), 127.4 (2,6-Ph), 121.6 (3-py), 119.3 (5-py), 40.4 (CH2). Anal.
Calc.: C, 78.00; H, 5.49; N, 5.02; S, 11.49. Found: C, 77.94; H,
5.45; N, 5.05; S, 11.56%. EI m/z 276 [M]+, [12C18H1514N32S 276].
13: 1H NMR: d 7.94 (2H, dd, J = 7.8, 1.2 Hz, 2,6-Ph), 7.65 (1H, m,
4-py), 7.56 (3H, m, 5-py and 2,6-SePh), 7.45 (3H, m, 3,4,5-Ph), 7.26
(3H, m, 3,4,5-SePh), 7.11 (1H, d, J = 7.8 Hz, 3-py), 4.36 (2H, s, 2H,
CH2). 13C{1H} NMR: d 158.9 (2-py), 156.9 (6-py), 137.7 (4-py),
133.8 (2,6-SePh), 130.3 (1-SePh) 129.5 (4-Ph), 129.3 (3,5-SePh),
128.9 (3,5-Ph), 127.6 (4-SePh), 127.4 (2,6-Ph), 121.7 (3-py), 119.0
(5-py), 33.7 (CH2). Anal. Calc.: C, 66.58; H, 4.60; N, 4.28. Found:
C, 66.67; H, 4.66; N, 4.32%. EI m/z 323 [M]+, [12C18H1514N80Se 323].
4.1. Synthesis of reagents and ligands
4.1.1. 6-Phenyl-2-methylpyridine
A degassed solution of Na2CO3 (1.39 g, 13.11 mmol) in water
(12.0 mL) was added to a solution of 2-bromo-6-methylpyridine
(0.66 mL, 5.81 mmol) and Pd(PPh3)4 (0.34 g, 5 mol%) in toluene
(26.0 mL), followed by a solution of phenylboronic acid (1.06 g,
8.72 mmol) in methanol (8.0 mL). The mixture was stirred at
95 °C for 6 h under argon, and another 0.5 equiv. of phenylboronic
acid and 1 mol% of catalyst were added. After a further 6 h the
solution was cooled to room temperature and treated with satu-
rated Na2CO3. The product was extracted with CH2Cl2
(3 ꢄ 25 mL), the combined organic layers were washed with satu-
rated NaCl solution, dried over Na2SO4 and the solvent removed in
a vacuum to give a pale yellow oil (0.91 g, 98%). Although not re-
quired, the product can be distilled (76–79 °C, 2.9 ꢄ 10ꢁ2 torr) to
give a colourless oil (0.64 g, 69%). 1H NMR: d 7.99 (2H, dd), 7.69
(1H, t), 7.48 (4H, m), 7.13 (1H, d), 2.69 (3H, s, CH3). 13C{1H}
NMR: d 158.4, 156.9, 137.9, 129.3, 128.9, 127.5, 127.4, 122.2,
118.4, 24.5 (CH3).
The ligands pyCH2SMe (1), 4-MepyCH2SMe (3), 6-MepyCH2SMe
(4), and pyCH2SPh (6) were prepared as reported.3e The same
method was used to prepare the known ligands pyCH2SeMe (2),
pyCH2SePh (7), 6-MepyCH2SPh (10), 6-MepyCH2SePh (11), and
the new ligands 6-PhpyCH2SMe (5), 4-MepyCH2SPh (8), 4-Me-
pyCH2SePh (9), 6-PhpyCH2SPh (12) and 6-PhpyCH2SePh (13). The
general method, is followed by slight variations in work-up and
purification of products.
4.1.4. 2-Phenylselenomethylpyridine (7); 4-methyl-2-
phenylthiomethylpyridine (8); 4-methyl-2-
phenylselenomethylpyridine (9); 6-methyl-2-
phenylthiomethylpyridine (10); 6-methyl-2-
phenylselenomethylpyridine (11)
These ligands were prepared in a similar manner to 2, 12, 13
and, although the products do not require further purification
(49–74% yield), they were distilled under vacuum to give products
as a yellow oil (7, 108–112 °C, 4.0 ꢄ 10ꢁ2 torr, 54%; 9, 118–122 °C,
3.1 ꢄ 10ꢁ2 torr, 51%; 11, 114–1182 °C, 2.8 x 10ꢁ2 torr, 54%), and
pale yellow oil (8, 112–122 °C, 4.2 ꢄ 10ꢁ2 torr, 25%; 10, 104–
110 °C, 4.2 ꢄ 10ꢁ2 torr, 32%).
7: 1H NMR: d 8.50 (1H, d, J = 4.8 Hz, 6-py), 7.54 (1H, m, 4-py),
7.47 (2H, m, 2,6-SePh), 7.24 (3H, m, 3,4,5-SePh), 7.10 (2H, m, 3,5-
py), 4.23 (2H, s, CH2); 13C{1H} NMR: d 158.8 (2-py), 149.3 (6-py),
137.0 (4-py), 133.9 (2,6-SePh), 130.1 (1-SePh), 129.3 (3,5-SePh),
127.7 (4-SePh), 123.4 (3-py), 122.0 (5-py), 33.8 (CH2). Anal. Calc.:
C, 57.89; H, 4.58; N, 5.41. Found: C, 58.07; H, 4.47; N, 5.64%. EI
m/z 247 [M]+, [12C12H1114N80Se 247].
4.1.2. 6-Phenyl-2-methylthiomethylpyridine (5)
A solution of LiBun (0.44 mL, 1.6 M in hexane) was added drop-
wise to a stirred solution of 6-phenyl-2-methylpyridine (0.10 g,
0.59 mmol) in Et2O (25 mL) at ꢁ78 °C. The solution was allowed
to warm to room temperature, and then added dropwise to a stir-
red solution of dimethyldisulfide (0.06 mL, 0.65 mmol) in THF
(25 mL) at ꢁ78 °C. The solution was allowed to warm to room tem-
perature and stirred for 3 h. Water (10 mL) was added and the
aqueous layer extracted with Et2O (3 ꢄ 25 mL). Solvent was re-
moved in a vacuum from the combined organic phases to give a
pale yellow oil (0.12 g, 94%). 1H NMR: d 8.01 (2H, dd, J = 7.8,
1.2 Hz, 2,6-Ph), 7.78 (1H, m, J = 7.8 Hz, 4-py), 7.62 (1H, d, 5-py),
7.46 (3H, m, 3,4,5-Ph), 7.36 (1H, d, J = 7.5 Hz, 3-py), 3.95 (2H, s,
8: 1H NMR: d 8.39 (1H, d, J = 5.1 Hz, 6-py), 7.33 (2H, dd, J = 8.4,
1.5 Hz, 2,6-SPh), 7.24 (2H, m, 3,5-SPh), 7.17 (2H, m, 3-py and 4-
SPh), 7.00 (1H, d, 5-py), 4.25 (2H, s, CH2), 2.30 (3H, s, CH3);
13C{1H} NMR: d 157.3 (2-py), 153.8 (4-py), 148.6 (6-py), 132.7
(1-SPh), 129.8 (2,6-SPh), 129.1 (3,5-SPh), 126.6 (4-SPh), 124.3 (3-
py), 123.5 (5-py), 40.2 (CH2), 21.3 (CH3). Anal. Calc.: C, 72.68; H,
6.15; N, 6.43; S, 14.64. Found: C, 72.52; H, 6.09; N, 6.51; S,
14.89%. EI m/z 214 [M]+
[ C
H1314N32S 214].
12
13
9: 1H NMR: d 8.38 (1H, d, J = 5.1 Hz, 6-py), 7.46 (2H, m, 2,6-
SePh), 7.23 (3H, m, 3,4,5-SePh), 6.91 (2H, m, 3,5-py), 4.19 (2H, s,

Table 5
Crystal/refinement data.
13ab
a
1
Complex
7a
9a
9aꢀMeCN
10aꢀMeNO2
11a
3aꢀ 4MeNO2
1
Formula
Mr/Da
C12H11Cl2NPdSe
425.5
C13H13Cl2NPdSe
439.5
C13H13Cl2NPdSeꢀCH3CN
C39H39Cl6N3Pd3S3ꢀMeNO2
C26H26Cl4N2Pd2Se2
879.0
C18H14ClNPdSe
465.1
C8H11Cl2NPdSꢀ 4CH3NO2
345.0
480.6
1238.9
Crystal system
Space group
triclinic
ꢀ
monoclinic
monoclinic
monoclinic
Orthorhombic
Monoclinic
Monoclinic
P21/n ðC52h; #14Þ
P21/c ðC52h; #14Þ
P21/c ðC52h; #14Þ
Pca21 ðC52 ; #29Þ
P21/n ðC52h; #14 ð
v
ariantÞÞ
Cc ðC4s ; No:9Þ
19.343(4)
18.935(8)
18.015(9)
1
P1 ðCi ; #2Þ
8.284(4)
10.059(2)
16.272(3)
105.857(18)
92.38(4)
110.74(3)
1205.3(7)
1.901
v
a (Å)
b (Å)
c (Å)
9.236(3)
13.258(7)
10.802(3)
16.701(3)
12.229(2)
15.961(3)
10.055(2)
10.968(2)
16.437(4)
20.330(4)
11.577(3)
20.364(4)
7.970(5)
14.790(4)
12.410(3)
a
(°)
b (°)
95.95(3)
117.43(3)
106.26(2)
92.73(2)
101.24(4)
c
(°)
V (Å3)
1315.6(9)
2.148
4
4.6
0.20, 0.18, 0.18
50
2893.3(12)
2.018
8
4.1
0.22, 0.22, 0.20
50
1740.1(6)
1.834
4
4793(20
1.717
4
1.62
0.10,0.10,0.04
50
1461.2(11)
1.998
6471(4)
1.910
16
Dc (g cmꢁ3
Z/f.u.
)
4
2.1
2
lMo (mmꢁ1
)
3.5
4.1c
3.6
Specimen (mm3)
0.24, 0.20, 0.20
50
0.32, 0.28, 0.28
50
0.05,0.05,0.03
51
0.20,0.20,0.20
50
2hmax (°)
Nt
N (Rint
No
4381
4218 (0.016)
3487
4634
2338 (0.079)
2167
7989
5005 (0.041)
4551
3008
2907 (0.059)
2633
42 813
8433 (0.070)
6727
15 725
2266 (0.045)
2266
5855
)
5855 (ꢁ)
5557
R1
0.043
0.034
0.056
0.080
0.056
0.031
0.022
wR2 (a,b)
S
0.125 (0.075,2.0)
1.04
0.091 (0.051,0.64)
1.08
0.14 (0.093,2.8)
1.12
0.23 (0.20)
1.10
0.125 (0.043,11.3)
1.02
0.076 (0.039,7.3)
1.07
0.053 (0.035)
1.05
a
b
c
xabs = 0.20(4).
xabs = 0.006(6).
k = 0.75277 Å.

86
R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
CH2), 2.24 (3H, s, CH3); 13C{1H} NMR: d 158.4 (2-py), 149.1 (6-py),
148.1 (4-py), 133.8 (2,6-SePh), 130.1 (1-SePh), 129.2 (3,5-SePh),
127.6 (4-SePh), 124.3 (3-py), 123.1 (5-py), 33.8 (CH2), 21.2 (CH3).
Anal. Calc.: C, 59.52; H, 4.89; N, 5.44. Found: C, 59.55; H, 5.00; N,
5.34%. EI m/z 261 [MꢁH]+, [12C13H1214N80Se 261].
C, 39.84; H, 3.38; N, 3.62; S, 8.28. Found: C, 39.77; H, 3.34; N, 3.57;
S, 8.17%.
11a: dark yellow solid (0.14 g, 80%). 1H NMR: d 7.79 (2H, s b,
py), 7.60 (6H, m b, py and Ph), 7.29 (8H, m b, py and Ph), 5.14
(2.8H, s b, CH2, major), 4.27 (1.2H, s b, CH2, minor), 3.19 (6H, br
10: 1H NMR: d 7.49 (1H, m, 4-py), 7.33 (2H, dd, J = 6.9, 1.2 Hz,
2,6-SPh), 7.24 (2H, m, 3,5-SPh), 7.18 (2H, m, 3-py and 4-SPh),
7.01 (2H, d, J = 7.5 Hz, 5-py), 4.25 (2H, s, CH2), 2.55 (3H, s, 3H,
CH3); 13C{H} NMR: d 158.2 (2-py), 156.9 (6-py), 137.3 (4-py),
136.3 (1-SPh), 129.7 (2,6-SPh), 129.1 (3,5-SPh), 126.5 (4-SPh),
122.0 (5-py), 120.2 (3-py), 40.5 (CH2), 24.5 (CH3). Anal. Calc.: C,
72.52 (72.72); H, 6.09 (6.12); N, 6.51 (6.40); S, 14.89 (14.61).
s, 6-CH3). Anal. Calc.: C, 35.59; H, 3.05; N, 3.24. Found: C, 35.52;
12
H, 2.98; N, 3.19%. LSIMS m/z 404 [1/2(MꢁCl)]+,
[ C H13
13
35Cl14N79Se106Pd 404].
12a: dark yellow solid (0.15 g, 92%). 1H NMR: d 7.98 (4H, m),
7.81 (2H, m), 7.74 (2H, d), 7.6 (2H, m), 7.4 (12H, m b), 7.11 (4H,
m), 5.05 (2H, s, CH2, major), 4.39(2H, s, CH2, minor). Anal. Calc.:
C, 51.58; H, 3.32; N, 3.30; S, 7.92. Found: C, 51.69; H, 3.37; N,
3.35; S, 7.67%. LSIMS m/z 383 [MꢁCl]+, [12C18H1414N32S106Pd 383].
13a: orange solid (0.17 g, 96%). 1H NMR: d 7.96 (4H, m), 7.81
(2H, m), 7.74 (2H, d), 7.6 (2H, m), 7.4 (12H, m b), 7.11 (4H, m),
5.05 (2H, s, CH2, major), 4.39 (2H, s, CH2, minor). Anal. Calc.: C,
46.58; H, 3.10; N, 3.09. Found: C, 46.48; H, 3.03; N, 3.01%. LSIMS
m/z 430 [MꢁCl]+, [12C18H1414N79Se106Pd 430].
Found: C, 72.72; H, 6.12; N, 6.40; S, 14.61%. EI m/z 214 [M]+
12
[
C
H1314N32S 214].
13
11: 1H NMR: d 7.47 (3H, m, 4-py and 2,6-SePh), 7.24 (3H, m,
3,4,5-SePh), 6.98 (1H, d, 5-py), 6.91 (1H, d, J = 7.8 Hz, 3-py), 4.22
(2H, s, CH2), 2.53 (3H, s, CH3); 13C{1H} NMR: d 158.0 (6-py),
157.9 (2-py), 137.4 (4-py), 134.0 (2,6-SePh), 130.2 (1-SePh),
129.2 (3,5-SePh), 127.7 (4-SePh), 121.8 (5-py), 120.4 (3-py), 33.7
(CH2), 24.4 (CH3). Anal. Calc.: C, 59.44; H, 5.17; N, 5.18. Found: C,
59.55; H, 5.00; N, 5.34%. EI m/z 261 [M]+, [12C13H1314N80Se 261].
4.3. Structural determinations
Data for 3a, 7a, the two polymorphs of 9a and 13a were col-
4.2. Synthesis of complexes
lected at ꢁ80 °C with an Enraf Nonius Turbo CAD4 with Mo K
a
radiation (0.71073 Å) on crystals mounted on glass fibres. Full
A suspension of PdCl2(NCMe)2 (0.10 g, 0.39 mmol) and ligand
(0.46 mmol) in dry acetonitrile (25 mL) was stirred for 12 h at
room temperature to give yellow solutions. The volume was re-
duced to ca. 5 mL in a vacuum, and diethyl ether added to precip-
itate the complexes which were collected by filtration and washed
with diethyl ether.
spheres of CCD area-detector diffractometer data for 10a were col-
lected (Bruker AXS,
x-scans, monochromatic Mo Ka radiation,
k = 0.71073 Å, T ca. 153 K) at the University of Western Australia.
Data for 11a was collected at ꢁ173 °C for crystals mounted on a
Hampton Scientific cryoloop at the PX1 beamline of the Australian
Synchrotron [31]. The structures were solved by direct methods
with SHELXS-97, refined using full-matrix least-squares routines
against F2 with SHELXL-97 [32], and visualised using X-SEED [33].
All non-hydrogen atoms were refined anisotropically. Nitrogen-
bound and O-bound hydrogen atoms were positionally refined
and other hydrogen atoms were placed in calculated positions
and refined using a riding model with fixed C–H distances of
0.95 Å (sp2C–H), 0.99 Å (CH2), 0.98 Å (CH3). The thermal parame-
ters of all hydrogen atoms were estimated as Uiso(H) = 1.2Ueq(C)
except for CH3 where Uiso(H) = 1.5Ueq(C). Crystallographic data
are listed in Table 5.
3a: yellow solid (0.11 g, 85%). 1H NMR: d 8.92 (1H, d, J = 6 Hz, py),
7.58 (s, py), 7.39 (1H, d, py), 4.74, 4.41 (2H, AB spin system,
J = 16.5 Hz, CH2, Tc = 92 °C), 2.48 (3H, s, 4-CH3), 2.37 (3H, s, SCH3).
Anal. Calc.: C, 29.25; H, 3.42; N, 4.29; S, 9.61. Found: C, 29.07;
H, 3.35; N, 4.24; S, 9.70%. LSIMS m/z 295 [MꢁCl]+, [12C8H11
35Cl14N32S106Pd 295].
4a: yellow solid (0.12 g, 95%). 1H NMR: d 7.92 (1H, m b, py), 7.57
(1H, m b, py), 7.43 (1H, m b, py), 4.72 (2H, s b, CH2), 3.06 (3H, s b, 6-
CH3), 2.26 (3H, s b, SCH3). Anal. Calc.: C, 29.18; H, 3.38; N, 4.38; S,
9.45. Found: C, 29.07; H, 3.35; N, 4.24; S, 9.70%.
5a: dark yellow solid (0.13 g, 94%). 1H NMR: d 7.9 (6H, m), 7.6
(2H, m), 7.4 (6H, m b), 7.07 (2H, m), 4.58 (2H, s, CH2, major),
3.83 (2H, s, CH2, minor). Anal. Calc.: C, 43.75; H, 3.32; N, 3.86; S,
9.25. Found: C, 43.84; H, 3.40; N, 3.93; S, 9.00%. LSIMS m/z 321
[MꢁCl]+, [12C13H1214N32S106Pd 321].
4.4. Catalysis
The pre-catalyst was added to
a solution of aryl halide
7a: dark yellow solid (0.14 g, 87%). 1H NMR: d 9.17 (1H, d,
J = 5.4 Hz, py), 9.02 (m, py), 7.84 (2H, d, Ph), 7.66 (1H, d, py), 7.46
(4H, m, py and Ph), 5.22 and 4.66 (2H, AB spin system,
J = 15.9 Hz, CH2, Tc = 75 °C). Anal. Calc.: C, 33.67; H, 2.54; N, 3.18.
(1.5 mmol), n-butylacrylate (0.6 mL, 4.0 mmol), Na2CO3 (0.32 g,
3.0 mmol), Bun4NCl (0.63 g, 2.25 mmol), and NaO2CH (0.11 g,
1.65 mmol) in DMAc (5 mL) under Ar. The resulting mixture was
then stirred at 120 °C for 48 h under Ar. When cooled to room tem-
perature, diphenyl ether was added (0.170 g, 1.0 mmol); an aliquot
(1.5 mL) was diluted with CH2Cl2 (2.0 mL) and washed with an
aqueous solution saturated with NaCl (3 ꢄ 1.5 mL). The organic
layer was extracted, dried over MgSO4 and filtered. Catalysis did
not occur in the absence of a precatalyst. For NAIL catalysis,
Bun4NCl (2.48 g) was used and N,N-dimethylacetamide was
omitted.
Found: C, 33.87; H, 2.61; N, 3.29%. LSIMS m/z 390 [MꢁCl]+,
12
[
C
H1135Cl14N79Se106Pd 390].
12
8a: yellow solid (0.15 g, 96%). 1H NMR: d 8.91 (1H, d, py), 7.80
(2H, d, Ph), 7.58 (1H, s, py), 7.47 (3H, m, Ph), 7.38 (1H, d, py),
5.29 and 4.69 (2H, AB spin system, J = 17.4 Hz, CH2, Tc = 94 °C)
2.35 (3H, s, 4-CH3). Anal. Calc.: C, 39.90; H, 3.42; N, 3.63; S, 8.22.
Found: C, 39.77; H, 3.34; N, 3.57; S, 8.17%. LSIMS m/z 357 [MꢁCl]+,
12
[
C
H1335Cl14N32S106Pd 357].
13
9a: dark yellow solid (0.16 g, 92%). 1H NMR: d 9.00 (1H, d, py),
7.85 (2H, dd, Ph), 7.50 (1H, s, py), 7.44 (3H, m, py and Ph), 7.33 (1H,
d, py), 5.17 and 4.57 (2H, AB spin system, J = 15.9 Hz, CH2,
Tc = 72 °C), 2.31 (3H, s, 3H, 4-CH3). Anal. Calc.: C, 35.38; H, 2.92;
Acknowledgements
We thank the Australian Research Council for financial support.
Aspects of this research were undertaken on the PX1 beamline at
the Australian Synchrotron, Victoria, Australia. Julian Adams (Aus-
tralian Synchrotron) is acknowledged for technical support. The
views expressed herein are those of the authors and are not neces-
sarily those of the owner or operator of the Australian Synchrotron.
N, 3.12. Found: C, 35.52; H, 2.98; N, 3.19%. LSIMS m/z 404 [MꢁCl]+,
12
[
C
H1335Cl14N79Se106Pd 404].
13
10a: yellow solid (0.12 g, 81%). 1H NMR: d 7.86 (2H, m, py), 7.56
(2H, m, py), 7.44 (2H, m, py), 7.3 (10H, m, Ph), 5.22 (2.4H, s b, CH2,
major), 4.26 (1.6H, s b, CH2, minor, 3.23 (6H, s, 6-CH3). Anal. Calc.:

R.C. Jones et al. / Inorganica Chimica Acta 363 (2010) 77–87
87
(c) T. Schultz, N. Schnees, A. Pfaltz, Appl. Organomet. Chem. 18 (2004) 595;
A. Scrivanti, M. Bertoldini, U. Matteoli, V. Beghetto, S. Antonaroli, A. Marini, B.
Crociani, J. Mol. Catal. A 235 (2005) 12.
Appendix A. Supplementary material
CCDC 745461, 745462, 745463, 745464, 745465, 745466 and
745467 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif. upplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.ica.2009.10.002.
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