Synthesis and crystal structure of dinuclear and tetranuclear palladium dppm complexes. [Pd2(μ-dppm)2(vpy)Cl] and [Pd4(μ-dppm)4 (μ-X)2](ClO4)2 (X = Cl, Br and I)

Article abstract of DOI:10.1016/S0277-5387(98)00163-6

Reaction of the intermediate [Pd₂(μ-dppm)₂]² which was prepared from [Pd₂(μ-dppm)₂X₂] (X = Cl, Br and I) and AgClO₄ in ethanol with 2-vinylpyridine (vpy) afforded dinuclear Pd(I) dppm complex [Pd₂(μ-dppm)₂(vpy)Cl] (1). When the intermediate [Pd₂(μ-dppm)₂]² was allowed to stand for a few days, tetranuclear Pd dppm complex [Pd₄ (μ-dppm)₄(μ-X)₂](ClO₄)₂ (X = Cl (2), Br (3) and I (4)) was systematically formed. The structure for 1 and 2 were crystallographically determined. On complex 1 two Pd atoms are doubly bridged by two dppm ligands to form an eight-membered Pd₂P₄C₂ framework in a twist-chair conformation. Each Pd atoms is also coordinated by the Cl atom and the N atom of vpy in unsymmetrical side-by-side mode. The Pd-Pd distance is 2.597(2) A and the torsion angle between two Pd₂P₂ plane is 43.2°. On the other hand four Pd atoms on 2 are bridged by four dppm ligands to form a rectangular Pd₄ core, which is composed of the shorter Pd-Pd separations (2.590(1) A) and the close Pd · · · Pd separations (3.818(2) A). The later Pd · · · Pd separation is also bridged by the Cl atom. The Pd-P distance (2.351(1) A) bridging the close Pd · · · Pd separation is rather longer than that (2.238(2) A) bridging the shorter Pd-Pd separation.

Full text of DOI:10.1016/S0277-5387(98)00163-6

Polyhedron Vol[ 06\ No[ 19\ pp[ 2546Ð2552\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99052Ð5
Synthesis and crystal structure of dinuclear and
tetranuclear palladium dppm complexes[
ðPd1"m!dppm#1"vpy#ClŁ and ðPd3"m!dppm#3
"m!X#1Ł"ClO3#1 "X ꢀ Cl\ Br and I#
Masahiko Maekawa\aꢀ Megumu Munakata\b Takayoshi Kuroda!Sowab and
Yusaku Suenagab
aResearch Institute for Science and Technology\ Kinki University\ 2!3!0 Kowakae\ Higashi!Osaka\
Osaka\ 466!7491\ Japan
bDepartment of Chemistry\ Kinki University\ 2!3!0 Kowakae\ Higashi!Osaka\ Osaka\ 466!7491\ Japan
"Received 7 January 0887^ accepted 6 April 0887#
Abstract*Reaction of the intermediate ðPd1"m!dppm#1Ł1¦ which was prepared from ðPd1"m!dppm#1X1Ł "X ꢁ Cl\
Br and I# and AgClO3 in ethanol with 1!vinylpyridine "vpy# a}orded dinuclear Pd"I# dppm complex ðPd1"m!
dppm#1"vpy#ClŁ "0#[ When the intermediate ðPd1"m!dppm#1Ł1¦ was allowed to stand for a few days\ tetranuclear
Pd dppm complex ðPd3 "m!dppm#3"m!X#1Ł"ClO3#1 "X ꢁ Cl "1#\ Br "2# and I "3## was systematically formed[ The
structure for 0 and 1 were crystallographically determined[ On complex 0 two Pd atoms are doubly bridged by
two dppm ligands to form an eight!membered Pd1P3C1 framework in a twist!chair conformation[ Each Pd
atoms is also coordinated by the Cl atom and the N atom of vpy in unsymmetrical side!by!side mode[ The PdÐ
Ä
Pd distance is 1[486"1# A and the torsion angle between two Pd1P1 plane is 32[1>[ On the other hand four Pd
atoms on 1 are bridged by four dppm ligands to form a rectangular Pd3 core\ which is composed of the shorter
Ä
Ä
PdÐPd separations "1[489"0# A# and the close Pd = = = Pd separations "2[707"1# A#[ The later Pd = = = Pd separation
Ä
is also bridged by the Cl atom[ The PdÐP distance "1[240"0# A# bridging the close Pd = = = Pd separation is rather
longer than that "1[127"1# A# bridging the shorter PdÐPd separation[ Þ 0887 Elsevier Science Ltd[ All rights
Ä
reserved[ Þ 0887 Elsevier Science Ltd[ All rights reserved
Keywords] palladium complexes^ dinuclear complexes^ tetranuclear complexes^ crystal structures^ bidentate
phosphine ligands^ nitrogen donor ligands[
———————————————————————————————————————————————
Bidentate phosphine ligands such as bis"diphenyl! "face!to!face# ð08\ 19Ł have been known in dinuclear
Pd"I# complexes[ It has been reported that dinuclear
Pd"I# dppm complexes in a side!by!side mode react
with small molecules such as CO\ SO1\ RCN\
CR1CR1 to a}ord those in A!frame mode via a inser!
tion reaction into a PdÐPd bond ð03\ 06\ 10\ 11Ł[
Although crystal structures of several trinuclear ð12Ð
15Ł and tetranuclear Pd complexes ð16Ð29Ł bridged by
dppm ligands has been investigated\ investigations to
polynuclear Pd dppm complexes are relatively few and
their structure\ property and reactivity are not fully
researched ð1Ł[
phosphino#methane "dppm# and 1!"diphenylphos!
phino#pyridine "Ph1Ppy# are useful bridging ligands
to form homo! and heteronuclear Pd"I# complexes
with a close metal!metal distance[ There has been con!
siderable interests in synthesis\ structure and reaction
of dinuclear Pt"I# and Pd"I# complexes ð0Ð2Ł\ since
these dinuclear complexes can provide unique proper!
ties for an unusual coordination mode of small mol!
ecules\ their activation and catalytic transformation[
Three typical coordination modes of "a# ðPd1"m!
dppm#1L1Ł "side!by!side# ð3Ð8Ł\ "b# ðPd1"m!X#"m!
dppm#1L1Ł "A!frame# ð09Ð07Ł and "c# ðPd1"m!dppm#1L3Ł
We have so far interested in the reactivity of the
intermediate ðPd1"m!dppm#1Ł1¦ which was prepared
from ðPd1"m!dppm#1X1Ł and AgClO3 in alcohol
"Scheme# ð20\ 21Ł[ It has been reported that reaction of
ꢀAuthor to whom correspondence should be addressed[
2546

2547
Masahiko Maekawa et al[
Scheme 0[
the intermediate ðPd1"m!dppm#1Ł1¦ with 3!mercapto! solvents were available from Merck and were dried by
pyridine "pySH# as a S!donor ligand a}orded the di! molecular sieves before use[ Tetramethylsilane and
nuclear Pd"I# complex ðPd1"m!dppm#1"HpyS#1Ł"ClO3#1 74) H2PO3 in D1O were used as a reference\ respec!
ð20Ł[ In this study\ the reaction of the intermediate tively[
ðPd1"m!dppm#1Ł1¦ with 1!vinylpyridine "vpy# as a N
donor ligand was furthermore attempted and dinu!
Synthesis of ðPd1"m!dppm#1"vpy#ClŁClO3 "0#
clear Pd"I# complex ðPd1"m!dppm#1"vpy#ClŁ "0# was
obtained[ It was found that tetranuclear Pd complex
ðPd3"m!dppm#3"m!X#1Ł"ClO3#1 "XꢁCl"1#\ Br"2# and
ðPd1"m!dppm#1Cl1Ł "10[9 mg\ 9[91 mmol# and
AgClO3 "8[9 mg\ 9[93 mmol# were mixed in ethanol
"09 ml# for 2 hours[ The reddish brown suspension
was _ltered[ The vpy ligand "0[9 ml# was then added
I"3## were systematically constructed by the standing
of the intermediate ðPd1"m!dppm#1Ł1¦ in ethanol[ The
to the _ltrate[ After stirring for 1 hours\ the orange
structure for 0 and 1 were determined by a single
suspension was _ltered and the _ltrate was sealed in a
crystal X!ray structure analysis[
4 mm diameter glass tube[ The orange solution was
allowed to stand for 0 week at an ambient temperature
and the yellow crystals were collected[ Yield[ 06 mg
EXPERIMENTAL
"21)#[ Found] C\ 44[72^ H\ 2[88^ N\ 0[98[ Calc[ for
General
Pd1P3C46NCl1O3H40] C\ 45[93 H\ 3[10^ N\ 0[04[ IR
0
"CsI\ cm−0#] 0324"nPÐC#[ H NMR "CDCl2#] d "6[81
Dinuclear Pd"I# dppm complex ðPd1"m!dppm#1X1Ł
and 6[39# "39 H\ br m\ Ph# and 3[28 "3 H\ br s\ CH1#
"XꢁCl\ Br and I# were prepared according to the
literature
for dppm\ 7[58 "0 H\ br s\ 1!H#\ 6[60 "0 H\ br s\ 3!H#\
6[09 "0 H\ br s\ 4!H#\ 5[76 "0 H\ br s\ 2!H#\ 5[62 "0 H\
ð11Ł[
Bis"diphenylphosphino#methane
"dppm#\ 1!vinyl!pyridine "vpy# and AgClO3 were pur!
chased from Aldrich and used without further puri!
_cation[ All organic solvents were dried by general
procedures and distilled before use[ All operations
were carried out using standard Schlenk techniques
br s\ CH
1
#\ 5[39 "0 H\ br d\ CH1# and 4[79 "0 H\ br
1
d\ ÐCH1# for vpy[ 20P NMR "ethanol#] −0[17[ UV!
VIS "nm "e"M−0 cm−0##\ ethanol#] 221 "0[6×093#\ 284
"6×092#[
under Ar[ IR spectra were measured with a JASCO Synthesis of ðPd3"m!dppm#3"m!Cl#1Ł"ClO3#1 "1#
7999 FT IR spectrometer\ using a CsI pellet[ 0H NMR
and 20P NMR spectra were obtained with a JEOL
ðPd1"m−dppm#1Cl1Ł "10[9 mg\ 9[91 mmol# and
GSX 169 FT NMR spectrometer at 12>C[ Deuterium AgClO3 "8[9 mg\ 9[93 mmol# were mixed in ethanol

Synthesis and crystal structure of dinuclear and tetranuclear palladium dppm complexes
2548
"09 ml# for 2 hours[ The reddish brown suspension Pd3I1P7C099H77Cl1O7] C\ 38[60^ H\ 2[56[ IR "CsI\
0
was _ltered and the _ltrate was sealed in a 4 mm diam! cm−0#] 0324 "nPÐC#\ 0985 "nClO3#[ H NMR "CDCl2#] d
eter glass tube[ The reddish brown solution was "6[86\ 6[37 and 6[35# "79 H\ m\ Ph#\ 3[28 "7 H\ br s\
allowed to stand at an ambient temperature for 2 CH1#[ 20P NMR "ethanol\ 12>C#] −3[80[ UV!VIS "nm
days and the red prism crystals were collected[ Yields[ "e"M−0 cm−0##\ THF#] 231 "0[2×093#\ 333 "8[8×092#\
04 mg "58)#[ Found] C\ 42[10^ H\ 2[54[ Calc[ for 401 "6[5×092#[
Pd3Cl3P7O7C099H77] C\ 42[68^ H\ 2[86[ IR "CsI\ cm−0#]
0
0326 "nPÐC#\ 0987 "nClO3#[ H NMR "CDCl2#] d "6[87\
Data collection\ structure solution and re_nements for
6[40 and 6[34# "79 H\ m\ Ph#\ 3[30 "7 H\ tt\ CH1#[ 20P
0 and 1
NMR "ethanol#] −3[80[ UV!VIS "nm "e"M−0 cm−0##\
THF#] 247 "0[9×093#\ 320 "7[6×092#\ 401 "7[6×092#[
A suitable crystal for 0 or 1 was attached to the end
XPS "eV#] 231[8 "2d2:1#\ 226[4 "2d4:1#[
of a glass _ber and were mounted on a Rigaku AFC!
4R di}ractometer with a graphite mono!chromated
Ä
Synthesis of ðPd3"m!dppm#3"m!X#1Ł"ClO3#1 "XꢁBr"2# Mo Ka radiation "l ꢁ 9[60958 A#[ The detailed
and I"3##
measurement conditions and crystal data are sum!
marized in Table 0[ The intensity data were collected
In a similar manner as 1\ red brick crystals of 2 or at 12>C using the v scan technique for 0 and v!1u
red needle crystals of 3 were obtained using ðPd1"m! scan technique for 1[ The re~ection data of 4610 and
dppm#1Br1Ł "34[5 mg\ 3[9×09−4 mol# or ðPd1"m! 00111 re~ections were collected[ On 0 the intensities of
dppm#1I1Ł "38[4 mg\ 9[93 mmol# and AgClO3 "07[9 mg\ three representative re~ections which were measured
9[97 mmol# in ethanol "09 ml#[ 2] Yields[ 06 mg "39)#[ after every 049 re~ections remained constant through
Found] C\ 40[14^ H\ 2[47[ Calc[ for Pd3Br1P7C099H! data collection\ indicative of crystal and electronic
77Cl1O7] C\ 40[62^ H\ 2[71[ IR "CsI\ cm−0#] 0326 "nPÐC#\ stability[ No decay correction was applied[ On the
0985 "nClO3#[ 0H NMR "CDCl2#] d "6[86\ 6[41 and 6[35# other hand the intensities of three representative
"79 H\ m\ Ph#\ 3[17 "7 H\ t\ CH1#[ 20P NMR "ethanol#] re~ections on 1 which were measured after every 049
−3[85[ UV!VIS "nm "e"M−0 cm−0##\ THF#] 245 re~ections declined by 7[0)[ A linear correction fac!
"7[2×092#\ 324 "6[7×092#\ 404"6[4×092#[ 3] Yields[ tor was applied to the data to account for this
00 mg "26)#[ Found] C\ 38[26^ H\ 2[38[ Calc[ for phenomena[ The linear absorption coe.cient for Mo
Table 0[ Crystal data and measurement conditions for 0 and 1
Complex
0
1
Formula
M
Pd1P3C46NCl1O3H40
0110[53
Orthorhombic
P101010
00[771"4#
00[898"6#
27[565"4#
89[9
89[9
89[9
4362"2#
3
0[371
Pd3Cl3P7O7C099H77
1122[9
Triclinic
Crystal system
Space group
Þ
P0
Ä
a "A#
03[145"5#
04[237"8#
02[255"4#
003[54"2#
094[89"2#
51[63"2#
1249"3#
0
Ä
b "A#
Ä
c "A#
a ">#
b ">#
g ">#
2
Ä
U "A #
Z
Dcalc "gcm−2
#
Ä
0[466
9[60958
09[36
l"Mo Ka# "A#
9[60958
8[95
m"Mo Ka# "cm−0
#
Scan type
v
v!1u
Scan rate ">:min#
Scan width ">#
1umax ">#
1[9
7[9
9[65¦9[29 tan u
44[9
0[29¦9[29 tan u
44[9
No[ of re~ections measured
No[ of observations
F"999#
4610
1468 "I × 1s"I9##
1361
9[937
9[935
00111
6693 "I × 2s"I9##
0013
9[924
9[930
Ra
b
Rw
aR ꢀ >F9=−Fc>:=F9=[
bRw ꢀ ð"w"=F9=−=Fc=#1:w=F9=1#Ł0:1\ w ꢀ 3F91:s1"F9#1[

2559
Masahiko Maekawa et al[
Ka is 8[0 and 09[4 cm−0 for 0 and 1\ respectively[ gave the dinuclear Pd"I# complex ðPd1"m!dppm#1"vpy!
Azimuthal scans of several re~ections indicated no
need for an absorption correction[ The data were cor!
rected for Lorentz and polarization e}ects[
#ClŁ"ClO3# "0#[ Crystal structure of 0 is shown in Fig[
0\ together with the atomic labeling scheme[ Selected
bond distances and bond angles are listed in Table 1[
The two Pd atoms are doubly bridged by two dppm
ligands to form an eight!membered Pd1P3C1 ring
framework in a twist!chair conformation] The P"0#Ð
Pd"0#ÐP"3# and P"1#ÐPd"1#ÐP"2# angles are 065[1"1#
and 060[5"1#>\ respectively[ Each Pd atoms is fur!
thermore coordinated by the Cl atom and the N atom
of the vpy ligand\ providing an unsymmetrical side!
by!side mode[ The Cl"0#ÐPd"0#ÐPd"1#ÐN"0# axis is
almost linear[ The Pd"1#ÐPd"0#ÐCl"0# and Pd"0#Ð
Pd"1#ÐN"0# angle are 065[8"0# and 068[3"3#>\ respec!
tively\ which are slightly larger than those "058[0"2#\
062"0#># of other dinuclear Pd"I# dppm complexes ð3\
7Ł[
The structures were solved by a direct method
"MITHRIL# ð22Ł[ The non!hydrogen atoms were
re_ned anisotropically[ Hydrogen atoms were
included but not re_ned[ The _nal cycle of the full!
matrix least squares re_nement was based on 1468
and 6693 observed re~ections "I × 2s"I##\ and 507 and
448 variable parameters for 0 and 1\ respectively[
Reliability factors are de_ned as R ꢁ S"=Fo=−=Fc=#:
S=Fo= and Rw ꢁ ðSw "=Fo=−=Fc=#1:Sw=Fo=1Ł0:1\ where
1
1
w ꢁ 3Fo :s"Fo #[ The _nal R and Rw values were 9[937
and 9[935 for 0\ and 9[924 and 9[930 for 1\ respectively[
The maximum and minimum peaks on the _nal
di}erence Fourier map corresponded to 9[49 and
−2
−2
Ä
Ä
−9[49 eA for 0\ and 0[90 and −9[34 eA for 1\
respectively[ Atomic scattering factors and anomalous
dispersion terms were taken from the International
Tables for X!ray Crystallography\ Vol[ IV ð23Ł[ All
calculations were performed using the program
TEXSAN crystallographic software package ð24Ł[
Ä
The average PdÐP distance of 1[180"2# A is within
Ä
those "1[163"1#Ð1[291"1# A# of other dinuclear Pd"I#
dppm complexes in a side!by!side mode ð3Ð8\ 25Ł\
whereas the distance is rather shorter than those
Ä
"1[296"1#Ð1[247"3# A# in a A!frame mode ð09Ð07Ł[ The
Ä
Pd"0#ÐCl"0# distance of 1[270"4# A is similar to those
in other dinuclear Pd"I# dppm complexes ð6\ 7Ł[
Ä
The Pd"0#ÐPd"1# distance of 1[486"1# A is rather
RESULTS AND DISCUSSION
Ä
shorter than that "1[64A# in Pd metal and those
"1[483"1#Ð1[588"4# A# of other dinuclear Pd"I# dppm
Ä
Crystal structure of ðPd1"m!dppm#1"vpy#ClŁClO3 "0#
According to the Scheme\ reaction of the inter!
complexes with PdÐPd bond ð3Ð8Ł\ indicative of a
direct PdÐPd bond[ It has been theoretically reported
mediate ðPd1"m!dppm#1Ł1¦ with 1!vinylpyridine "vpy# on dinuclear Pd"I# dppm complexes that the twist
Fig[ 0[ Molecular structure of ðPd"m!dppm#1"vpy#ClŁ¦ "0# and the atomic labeling scheme[ Only Pd"0#\ Pd"1#\ P"0#\ P"1#\ P"2#\
Pd"3#\ Cl"0# and N"0# in the coordination sphere are labeled[

Synthesis and crystal structure of dinuclear and tetranuclear palladium dppm complexes
2550
Ä
Table 1[ Selected bond distance "A# and bond angles "># of 0
Pd"0#ÐPd"1#
Pd"0#ÐP"0#
Pd"1#ÐP"1#
Pd"1#ÐN"0#
1[486"1#
1[298"4#
1[201"4#
1[05"0#
Pd"0#ÐCl"0#
Pd"0#ÐP"2#
Pd"1#ÐP"3#
1[270"4#
1[297"4#
1[174"4#
Pd"1#ÐPd"0#ÐCl"0#
Pd"1#ÐPd"0#ÐP"2#
P"2#ÐPd"0#ÐCl"0#
Pd"0#ÐPd"1#ÐP"1#
Pd"0#ÐPd"1#ÐN"0#
P"1#ÐPd"1#ÐN"0#
P"0#ÐC"0#ÐP"1#
065[8"0#
76[6"0#
89[1"1#
76[4"0#
068[3"3#
80[8"3#
096"0#
Pd"1#ÐPd"0#ÐP"0#
P"0#ÐPd"0#ÐCl"0#
P"0#ÐPd"0#ÐP"2#
Pd"0#ÐPd"1#ÐP"3#
P"1#ÐPd"1#ÐP"3#
P"3#ÐPd"1#ÐN"0#
P"2#ÐC"1#ÐP"3#
77[7"0#
82[1"1#
065[1"1#
74[0"0#
060[5"1#
84[4"3#
093[7"7#
along the PdÐPd axis is due to anti!bonding inter! "X ꢁ Cl"1#\ Br"2# and I"3## was systematically formed[
actions of _lled metal d orbitals which are minimized This facts indicate that if no other suitable ligands
when the torsion angle equals 34> ð3\ 4Ł[ The twisted "or higher a.nity solvents and counter anion# were
conformation allows the ligands to span a shorter present in solution\ tetranuclear Pd complex ðPd3"m!
metal!metal bond[ The crystallographic data for 0 dppm#3"m!X#1Ł"ClO3#1 was constructed from ðPd1"m!
reveal that the torsion angle between the plane de_ned dppm#1Ł1¦ and dissolving halogen anions[ It has been
by "P"0#\ Pd"0#\ P"2# and Pd"1## and "P"1#\ Pd"1#\ reported that the similar complex ðPd3"m!dppm#3"m!
P"3# and Pd"1## is 32[1> and the PdÐPd distance is Cl#1ŁY1 "Y ꢁ BF3 and PF5# was obtained from reac!
Ä
1[486"1# A[ The torsion angle is more close to 34> and tion of ðPd1"m!dppm#1Cl1Ł with copper or gold com!
the PdÐPd distance is correspondingly more short\ plexes ð16Ł[ Crystal structure of 1 was shown in Fig[
compared with other dinuclear Pd"I# dppm complexes 1\ together with the atomic labeling scheme[ Selected
Ä
"ðPd1"m!dppm#1Br1Ł "28>\ 1[588"4# A# ð8Ł\ ðPd1"m! bond distances and bond angles are listed in Table 2[
Ä
dppm#1"SnCl2#ClŁ "30[2>\ 1[533"1# A# ð5Ł\ ðPd1"m! Complex 1 has the center of inversion at the midpoint
Ä
dppm#1"OCOF2#1Ł "33[4>\ 1[483"1# A# ð3Ł\ ðPd1"m! of Pd"0# = = = P"0?#[ Four Pd atoms are bridged by four
Ä
dppm#1"C5Cl4#1Ł "33[87>\ 1[5693"10# A# ð7Ł\ ðPd1"m! dppm ligands to form the rectangular Pd3 core\ which
4
Ä
dmpm#1Br1Ł "49[4>\ 1[592"0# A# #[ This facts illustrate consists of the shorter PdÐPd separations and the close
that the smaller deviation from 34> leads to the short! Pd = = = Pd separations[ The close Pd = = = Pd separations
ening of PdÐPd distance[
are moreover bridged by the Cl atom\ which is situated
0[34 A from the mean Pd3 plane[ All the Pd atoms are
Ä
coplanar[ The similar Pd3 core has been known in
ðPd3"m!dppm#3"m!Cl#1Ł"BF3#1, "CH2#1CO ð16\ 17Ł and
ðPd3"m!dppm#3"m!Cl#1Ł"ClO3#1,bpe ð18Ł[
Crystal structure of ðPd3"m!dppm#3"m!Cl#1Ł"ClO3#1
When the intermediate ðPd1"m!dppm#1Ł1¦ was
Ä
The shorter Pd"0#ÐPd"1# distance of 1[489"0# A is
Ä
allowed to stand in ethanol according to the Scheme\ rather shorter than that "1[64 A# in Pd metal and those
Ä
tetranuclear Pd complex ðPd3"m!dppm#3"m!X#1Ł"ClO3#1 "1[42Ð1[66 A# of other dinuclear Pd"I# complexes ð1\
Table 2[ Selected bond distances and bond angles for 1
Pd"0#ÐPd"1#
Pd"0#ÐCl"0#
Pd"0#ÐP"0#
Pd"1#ÐP"1#
P"0#ÐC"38#
P"2#ÐC"49#
1[489"0#
1[316"1#
1[126"1#
1[139"1#
0[703"3#
0[717"3#
Pd"0# = = = Pd"1?# 2[707"1#
Pd"1#ÐCl"0#
Pd"0#ÐP"2#
Pd"1#ÐP"3#
P"1#ÐC"38#
P"3#ÐC"49#
1[303"1#
1[220"0#
1[261"1#
0[737"3#
0[722"3#
P"0#ÐPd"0#ÐP"2#
Pd"1#ÐPd"0#ÐCl"0#
P"1#ÐPd"1#ÐP"3#
Pd"0#ÐPd"1#ÐCl"0?#
Pd"0#ÐCl"0#ÐPd"1?#
P"2#ÐC"49#ÐP"3?#
099[03"5#
77[69"4#
009[53"5#
65[05"4#
093[03"5#
010[5"1#
P"2#ÐPd"0#ÐCl"0#
Pd"1#ÐPd"0#ÐP"0#
P"3#ÐPd"1#ÐCl"0?#
Pd"0#ÐPd"1#ÐP"1#
P"0#ÐC"38#ÐP"1#
80[22"4#
71[12"4#
89[66"5#
71[33"4#
094[1"1#

2551
Masahiko Maekawa et al[
Fig[ 1[ Molecular structure of ðPd3"m!dppm#3"m!Cl#1Ł1¦ "1# and the atomic labeling scheme[ Only Pd"0#\ Pd"1#\ P"0#\ P"1#\
P"2#\ Pd"3#\ Cl"0#\ C"38#\ C"49#\ Pd"0?#\ Pd"1?#\ P"0?#\ P"1?#\ P"2?#\ P"3?#\ Cl"0?#\ C"38?# and C"49?# in the coordination sphere
are labeled[
3\ 4\ 26Ł\ indicative of a direct PdÐPd bond[ On the
SUPPLEMENTARY MATERIALS
other hand the close Pd"0# = = = Pd"1?# separation of
2[707"1# A are longer than that in Pd metal\ no indica!
Complete listings of the atomic coordinates\ bond
distances\ bond angles\ hydrogen atomic coordinates\
anisotropic thermal parameters\ and a listing of
observed and calculated structure factors for 0 and 1
are available from the Cambridge Crystallographic
Data Centre and the author[
Ä
tive of a direct PdÐPd bond[ The shorter PdÐPd dis!
Ä
tance is shorter than those "1[483"1#Ð2[221"0# A# of
other tetranuclear Pd complexes with the rectangular
Pd3 core ð16Ð32Ł[ The close Pd = = = Pd separation is
Ä
longer than those "1[720"0#Ð2[631"1# A# ð16Ð32Ł[
Consequently the Pd3 core is rather rectangular[
Acknowled`ements*We thank Mr[ Tamotsu Goto\ Mr[
Yasuhiro Tsujita and Mr[ Hisaaki Ohnishi for their assist!
ances[ This work was partially supported by a Grant!in!Aid
for Science Research from the Ministry of Education\ Science
and Culture in Japan[
Ä
The average PdÐP distance of 1[184"1# A is within
Ä
those "1[119"4#Ð1[242"6# A# of dinuclear ð3\ 4\ 26Ł\ tri!
nuclear ð13Ð15Ł and tetranuclear Pd complexes ð16Ð
29Ł bridged by dppm ligands[ It is interesting that
Ä
the PdÐP distance of 1[240"0# A bridging the close
Pd = = = Pd separation is very longer than that
"1[127"1# A# bridging the shorter PdÐPd bond[ The
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Ä
di}erence is considered due to both steric and elec!
tronic factors arising from the trans in~uence of the
PdÐPd bond and the bulk of the phenyl substituents[
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Ä
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Synthesis and crystal structure of dinuclear and tetranuclear palladium dppm complexes
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