Synthesis and conformational studies of palladium(II) complexes containing [Ph2P(O)NP(E)Ph2]- (E=S or Se)

Article abstract of DOI:10.1016/S0277-5387(98)00253-8

The ligands [Ph₂P(O)NP(E)Ph₂]^- (E=S I; E=Se II) can readily be complexed to a range of palladium(II) starting materials affording new six-membered Pd-O-P-N-P-E palladacycles. Hence ligand substitution reaction of the chloride complexes [PdCl₂(bipy)] (bipy=2,2′-bipyridine), [{Pd(μ-Cl)(L-L)}₂] (HL-L=C₉H₁₃N or C₁₂H₁₃N), [{Pd(μ-Cl)Cl(PMe₂Ph)}₂] or [PdCl₂(PR₃)₂] [PR₃=PPh₃; 2PR₃=Ph₂PCH₂CH₂PPh₂ or cis-Ph₂PCH=CHPPh₂] with either I (or II) in thf or CH₃OH gave [Pd{Ph₂P(O)NP(E)Ph₂-O,E}(bipy)]PF₆, [Pd{Ph₂P(O)NP(E)Ph₂-O,E}(L-L)], [Pd{Ph₂P(O)NP(E)Ph₂-O,E}Cl(PMe₂Ph)] or [Pd{Ph₂P(O)NP(E)Ph₂-O,E} (PR₃)₂]PF₆ in good yields. All compounds described have been characterised by a combination of multinuclear NMR [31 P{1 H} and 1 H] and IR spectroscopy and microanalysis. The molecular structures of five complexes containing the selenium ligand II have been determined by single-crystal X-ray crystallography. Three different ring conformations were observed, a pseudo-butterfly, hinge and in the case of all three PR₃ complexes, pseudo-boat conformations. Within the Pd-O-P-N-P-Se rings there is evidence for π-electron delocalisation.

Full text of DOI:10.1016/S0277-5387(98)00253-8

Polyhedron Vol[ 06\ Nos[ 14\ 15\ pp[ 3354Ð3362\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99142Ð7
Synthesis and conformational studies of
palladium"II# complexes containing
ðPh1P"O#NP"E#Ph1Ł− "EꢀS or Se#
Alexandra M[ Z[ Slawin\ Martin B[ Smith and J[ Derek Woollinsꢀ
Department of Chemistry\ Loughborough University\ Loughborough\ Leics LE00 2TU\ U[K[
"Received 18 April 0887^ accepted 07 June 0887#
Abstract*The ligands ðPh1P"O#NP"E#Ph1Ł− "EꢁS I^ EꢁSe II# can readily be complexed to a range of
palladium"II# starting materials a}ording new six!membered PdÐOÐPÐNÐPÐE palladacycles[ Hence ligand
substitution reaction of the chloride complexes ðPdCl1"bipy#Ł "bipyꢁ1\1?!bipyridine#\ ð"Pd"m!Cl#"LÐL##1Ł "HLÐ
LꢁC8H02N or C01H02N#\ ð"Pd"m!Cl#Cl"PMe1Ph##1Ł or ðPdCl1"PR2#1Ł ðPR2ꢁPPh2^ 1PR2ꢁPh1PCH1CH1PPh1 or
cis!Ph1PCHꢁCHPPh1Ł with either I "or II# in thf or CH2OH gave ðPd"Ph1P"O#NP"E#Ph1!O\E#"bipy#ŁPF5\
ðPd"Ph1P"O#NP"E#Ph1!O\E#"LÐL#Ł\ ðPd"Ph1P"O#NP"E#Ph1!O\E#Cl"PMe1Ph#Ł or ðPd"Ph1P"O#NP"E#Ph1!O\E#
"PR2#1ŁPF5 in good yields[ All compounds described have been characterised by a combination of multinuclear
0
NMR ð20P"0H# and HŁ and IR spectroscopy and microanalysis[ The molecular structures of _ve complexes
containing the selenium ligand II have been determined by single!crystal X!ray crystallography[ Three di}erent
ring conformations were observed\ a pseudo!butter~y\ hinge and in the case of all three PR2 complexes\ pseudo!
boat conformations[ Within the PdÐOÐPÐNÐPÐSe rings there is evidence for p!electron delocalisation[ Þ 0887
Elsevier Science Ltd[ All rights reserved
Keywords] metallacycles^ palladium^ ligands^ X!ray
———————————————————————————————————————————————
INTRODUCTION
through both E donor atoms although the propensity
to adopt a range of other di}erent bonding modes has
been reported ð5Ð8\ 16\ 20\ 21\ 23Ł[ One particularly
interesting feature that has emerged from the extensive
studies concerning the co!ordination chemistry of
ðR1P"E#NP"E#R1Ł− is the ability of the MÐEÐPÐNÐPÐ
E chelate to exist in di}erent ring conformations[ An
initial report from this laboratory revealed that by
modifying the exocyclic substituents "Ph vs OPh#
bound to phosphorus in ðR1P"S#NP"S#R1Ł− the PtÐSÐ
PÐNÐPÐS ring conformation in ðPt"R1P"S#NP"S#R1!
S\S?#"PR?2#1ŁPF5 "RꢁPh or OPh^ R?ꢁMe or Et# is
signi_cantly altered ð13Ł[ Silvestru and co!workers ð12Ł
found that in the manganese"I# complex ðMn"CO#3
"Ph1P"S#NP"S#Ph1!S\S?#Ł the unit cell contains two
independent monomeric molecules in which both MnÐ
SÐPÐNÐPÐS rings adopt dissimilar geometries[ In 0885
we reported ð06Ł an unusual homoleptic complex cis!
ðPd"Ph1P"O#NP"Se#Ph1!O\Se#1Ł which\ from X!ray
crystallographic studies\ revealed that both six!mem!
bered PdÐOÐPÐNÐPÐSe metallacycles assume dis!
parate ring conformations "pseudo!boat and chair!
like geometries# within the co!ordination sphere of the
molecule[
Over the last few years the co!ordination chemistry
of the monoanionic ligands ðR1P"E#NP"E#R1Ł−
"Rꢁalkyl\ aryl\ alkoxy\ aryloxy^ EꢁO\ S\ Se# has
been the subject of great interest due principally to its
close analogy to acetylacetonate "hereafter abbrevi!
ated acac# ð0Ð23Ł[ Whereas metal complexes of acac
"and its derivatives# have found important appli!
cations in diverse areas such as catalysis\ in organic
synthesis\ as medicinal based drugs\ CVD precursors
and in liquid crystals\ metal complexes of ðR1P"E#N!
P"E#R1Ł− have found only limited use as selective
metal extraction agents ð29Ł and NMR shift reagents
"Ref ð09Ł and references cited therein#[ Recently the
tetranuclear Ag"I# cluster ðAg"Ph1P"O#NP"O#Ph1#Ł3[
1EtOH has been shown to be an ole_n epoxidation
catalyst ð8Ł[
In common with acac\ the principal co!ordination
mode of ðR1P"E#NP"E#R1Ł− is that of chelation
ꢀ Author to whom correspondence should be addressed[
E!mail] j[d[woollinsÝlboro[ac[uk
3354

3355
Alexandra M[ Z[ Slawin et al[
ðPd"Ph1P"O#NP"S#Ph1!O\S#"C8H01N#Ł\ 2[ To
Since the mixed ligands ðPh1P"O#NP"E#Ph1Ł− "EꢁS
a
or Se# have been very poorly studied ð02\ 06Ł we report
here the synthesis and characterisation of some new
palladium"II# complexes of the type cis!
ðPdL1"Ph1P"O#NP"E#Ph1!O\E#Ł[ Five crystal structure
determinations have been performed on complexes
bearing di}erent trans ancillary ligands and fur!
thermore reveal that the six!membered PdÐOÐPÐNÐ
PÐSe metallacycles can adopt a range of di}erent ring
conformations[
solution of ð"Pd"m!Cl#"C8H01N##1Ł "9[939 g\ 9[9613
mmol# in thf "4 cm2# was added solid KðPh1P"O#
NP"S#Ph1Ł "9[961 g\ 9[042 mmol# in one portion[ After
stirring for ca[ 29 min\ the solvent was evaporated to
dryness in vacuo[ The residue was dissolved in CH1Cl1
"1 cm2#\ _ltered through a small Celite pad and
addition of petroleum ether "b[p[ 59Ð79>C\ ca[ 04 cm2#
gave a pale yellow solid 2[ The product was collected
by suction _ltration and dried in vacuo[ Yield] 9[973 g\
75)[
Using similar experimental conditions the following
compounds were prepared] ðPd"Ph1P"O#NP"Se#Ph1!
EXPERIMENTAL
O\Se#"C8H01N#Ł
3 "81)#\ ðPd"Ph1P"O#NP"S#Ph1!
General
O\S#"C01H01N#Ł 4 "85)# and ðPd"Ph1P"O#NP"Se#
Ph1!O\Se#"C01H01N#Ł 5 "78)#[ Slow di}usion of
petroleum ether "b[p[ 59Ð79>C# into a CH1Cl1 solution
of 5 over the course of ca[ 6 d gave crystals suitable
for X!ray crystallography[
ðPd"Ph1P"O#NP"S#Ph1!O\S#Cl"PMe1Ph#Ł\ 6[ To a
solution of ð"Pd"m!Cl#Cl"PMe1Ph##1Ł "9[931 g\
9[956 mmol# in thf "4 cm2# was added solid
KðPh1P"O#NP"S#Ph1Ł "9[954 g\ 9[027 mmol# in one
portion[ After stirring for ca[ 29 min\ the solvent was
evaporated to dryness in vacuo[ The residue was dis!
solved in CH1Cl1 "1 cm2#\ _ltered through a small
Celite pad and addition of petroleum ether "b[p[ 59Ð
79>C\ 19 cm2# gave a yellow solid[ The product was
collected by suction _ltration and dried in vacuo[
Yield] 9[977 g\ 82)[
All reactions were carried out in air using distilled
solvents[ The potassium salts of ðPh1P"O#NP"E#Ph1Ł−
"EꢁS or Se# ð06Ł and the metal complexes ð"Pd"m!
Cl#Cl"PMe1Ph##1Ł ð24Ł and ð"Pd"m!Cl#"LÐL##1Ł ðLÐ
Lꢁdimethylbenzylamine "C8H01N# and N\N!dime!
thyl!0!naphthylamine "C01H01N#Ł ð25Ł were prepared
according to previous published procedures[ The pal!
ladium"II# compounds ðPdCl1"PR2#1Ł ðPR2ꢁPPh2^
1PR2ꢁPh1PCH1CH1PPh1 or cis!Ph1PCHꢁCHPPh1Ł
were synthesised by stoichiometric addition of the
appropriate PR2 to ðPdCl1"cod#Ł "codꢁcycloocta!0\4!
diene# in dichloromethane[ ðPdCl1"bipy#Ł was pur!
chased from Aldrich Chemical Co[ and used without
further puri_cation[
Infrared spectra were recorded as KBr pellets in the
range 3999Ð199 cm−0 on a Perkin!Elmer System 1999
In
a similar manner ðPd"Ph1P"O#NP"Se#Ph1!
Fourier!transform spectrometer[ 20P"0H# NMR spec! O\Se#Cl"PMe1Ph#Ł\ 7\ was prepared in 69) yield[
tra "25[1 MHz# were recorded on a JEOL FX89Q
spectrometer with chemical shifts "d# in ppm "29[0#
to high frequency of 74) H2PO3 and coupling con!
stants "J# in Hz "22#[ All NMR spectra were mea!
sured in CDCl2 unless otherwise stated[ Elemental
analyses "Perkin!Elmer 1399 CHN Elemental Ana!
lyzer# were performed by the Loughborough Uni!
versity Analytical Service within the Department of
Chemistry[
Slow di}usion of petroleum ether "b[p[ 59Ð79>C# into
a CDCl2 solution of 7 over the course of ca[ 4 d gave
crystals suitable for X!ray crystallography[
ðPd"Ph1P"O#NP"Se#Ph1!O\Se#"Ph1PCH1CH1PPh1#Ł
ðPF5Ł\ 01[ The solids ðPdCl1"Ph1PCH1CH1PPh1#Ł
"9[937 g\ 9[9723 mmol# and KðPh1P"O#NP"Se#Ph1Ł
"9[936 g\ 9[980 mmol# were suspended in CH2OH
"1 cm2#[ After stirring for 1 h the yellow solution was
treated with a methanolic solution of ðNH3ŁðPF5Ł
"9[921 g\ 9[085 mmol\ 1[24 equivs[# whereupon a yel!
low precipitate formed immediately[ The mixture was
stirred for ca[ 09 min and the product 01 collected by
suction _ltration and dried in vacuo[ Yield] 9[971 g\
76)[
Palladium salts were provided on loan by Johnson
Matthey[
Preparations
The following cationic compounds were synthesised
ðPd"Ph1P"O#NP"S#Ph1!O\S#"bipy#ŁPF5\ 0 To the
solids ðPdCl1"bipy#Ł "9[943 g\ 9[051 mmol# and
KðPh1P"O#NP"S#Ph1Ł "9[965 g\ 9[050 mmol# was added
CH2OH "1 cm2#[ The solids dissolved to give an orange
solution and after stirring for ca[ 1 h a yellow suspen!
sion formed[ To this was added ðNH3ŁðPF5Ł "9[956 g\
9[300 mmol\ 1[43 equivs[# in CH2OH "ca[ 9[4 cm2# and
the mixture stirred for 09 min[ The solid 0 was isolated
by suction _ltration\ washed with CH2OH "ca[ 0 cm2#
and dried in vacuo[ Yield] 9[008 g\ 76)[ Compound 0
could be recrystallised from CH1Cl1:Et1O[
using
a similar method] ðPd"Ph1P"O#NP"S#Ph1!
O\S#"PPh2#1ŁðPF5Ł 8 "83)#\ ðPd"Ph1P"O#NP"Se#Ph1!
O\Se#"PPh2#1ŁðPF5Ł 09 "83)#\ ðPd"Ph1P"O#NP"S#Ph1!
O\S#"Ph1PCH1CH1PPh1#ŁðPF5Ł 00 "89)#\ ðPd"Ph1P
"O#NP"S#Ph1!O\S#"cis!Ph1PCHꢁCHPPh1#ŁðPF5Ł 02
"68)#
and
ðPd"Ph1P"O#NP"Se#Ph1!O\Se#"cis!
Ph1PCHꢁCHPPh1#ŁðPF5Ł 03 "81)#[ Slow di}usion of
diethyl ether into either CDCl2 "or CH1Cl1# solutions
of 09\ 01 or 03 over the course of several days gave
crystals suitable for X!ray crystallography[
Microanalytical and selected spectroscopic data for
compounds 0Ð03 are given in Tables 1 and 2[
In a similar manner ðPd"Ph1P"O#NP"Se#Ph1!O\Se#
"bipy#ŁPF5 1 was prepared in 77) yield[

Table 0[ Details of the X!ray data collections and re_nements for compounds 5\ 7\ 09\ 01 and 03
Compound
5
7
09
01
03
Empirical formula
Crystal colour\ habit
Crystal dimensions "mm#
Crystal system
C26H23Cl1N1OP1PdSe
pale yellow\ block
9[19×9[19×9[01
triclinic
C21H20ClNOP2PdSe
yellow:orange\ plate
9[09×9[02×9[02
triclinic
C59H49F5NOP4PdSe
yellow\ plate
9[92×9[09×9[19
monoclinic
C49H33F5NOP4PdSe
yellow\ plate
9[95×9[09×9[04
triclinic
C41H31NOP4F5PdSe
yellow\ plate
9[95×9[09×9[04
orthorhombic
P10101
Space group
P!0
P!0
P10:n
P!0
Lattice cell parameters
Ä
a "A#
00[547"1#
03[618"0#
00[437"0#
097[386"6#
092[05"0#
64[51"0#
0686"3#
1
00[570"0#
01[6683"7#
09[6799"8#
87[872"5#
090[997"7#
78[570"6#
0459"1#
1
00[780"2#
06[050"5#
16[750"3#
02[483"2#
06[336"1#
00[110"1#
80[72"0#
096[35"1#
092[63"0#
1340"8#
1
04[322"2#
18[393"4#
00[190"3#
Ä
b "A#
Ä
c "A#
a ">#
b ">#
g ">#
Volume "A #
Z value
090[74"1#
2
Ä
4453"1#
3
4972"1#
3
Formula weight
Densitycalc "g:cm2#
Absorption coe.cient "mm−0
1umax ">#
F"999#
Measured re~ections
Independent re~ections
739[8
0[44
6[67
019[0
733
4543
4238
648[23
0[51
7[47
019[1
659
0144[17
0[49
4[32
019[0
1425
0018[01
0[42
4[85
019[2
0025
0040[02
0[49
4[65
019[0
1201
3172
#
3895
3531
8982
7512
6561
6204
Observed re~ections ðI×1[9s"I#Ł
Re~ection:parameter ratio
Min[:max[ transmission
Weighting scheme\ pa
No[ of variables
2771
7[83]0
9[26\ 0[99
9[992
323
2258
8[20]0
9[81\ 0[99
9[993
251
1566
3573
6[87]0
9[46\ 0[99
9[993
476
1005
5[63]0
9[57\ 0[99
9[995
203
6[01]0
9[55\ 0[99
9[991
265
Final R\ Rw
Maximum D:s
Largest di}erence peak:hole "e A
9[937\ 9[936
2[29
9[69\ −9[78
9[928\ 9[930
9[90
9[47\ −9[59
9[942\ 9[936
9[99
9[50\ −9[32
9[933\ 9[926
9[94
9[36\ −9[54
9[979\ 9[968
9[86
9[68\ −9[47
−2
Ä
#
a The weighting scheme is as de_ned in Ref[ð28Ł[

3357
Alexandra M[ Z[ Slawin et al[
Table 1[ Microanalytical data "calculated values in par!
X!ray crystallo`raphy
entheses# for compounds 0Ð03
The crystal structures of complexes 5\ 7\ 09\ 01 and
03 were determined using a Rigaku AFC6S di}ract!
ometer with graphite!monochromated "CuÐKa# radi!
ation and v!scans[ Details of the data collections and
re_nements are given in Table 0[ Empirical absorption
corrections "DIFABS ð26Ł# were applied[ Psi!scans
proved unsatisfactory and DIFABS gave generally
superior results[ The structures were solved by the
heavy!atom method ð27Ł[ In 03 poor crystal quality
and the presence of an unidenti_ed solvent fragment
precluded complete re_nement of the structure[ The
Pd\ Se\ P\ N and O atoms were re_ned anisotropically
whilst the C and F atoms were re_ned isotropically
with the phenyl rings being re_ned as rigid bodies[ All
of the non!hydrogen atoms in the other structures
were re_ned anisotropically[ The CÐH atoms were
Analysis ")#
Compound
C
H
N
0
1
2
3
4
5
6
7
37[09 "37[59#
34[24 "35[94#
47[34 "47[89#
44[09 "44[94#
48[84 "59[84#
45[54 "46[19#
42[69 "42[84#
49[04 "49[59#
48[94 "48[54#
46[24 "46[39#
44[09 "44[49#
42[99 "42[19#
44[34 "44[59#
41[54 "42[14#
2[14 "2[24#
2[99 "2[19#
3[44 "3[79#
3[14 "3[49#
3[14 "3[44#
3[14 "3[14#
3[99 "3[39#
2[64 "3[09#
3[99 "3[19#
2[89 "3[99#
2[84 "3[09#
2[89 "2[84#
2[79 "2[84#
2[54 "2[64#
4[99 "4[99#
3[79 "3[64#
2[89 "3[04#
2[74 "2[89#
2[34 "2[84#
2[29 "2[69#
0[89 "0[84#
0[89 "0[74#
0[09 "0[04#
0[94 "0[09#
0[19 "0[29#
0[04 "0[14#
0[19 "0[29#
0[09 "0[14#
8
09
00
01
02
03
Ä
idealised and _xed "CÐH\ 9[84 A#[ No additional con!
straints or restraints were applied[ Re_nement was by
full!matrix least!squares methods based on F[ Cal!
culations were performed using TEXSAN ð28Ł[
Table 2[ Selected spectroscopic data for compounds 0Ð03
Compound
d"PO#
d"PE#a
d"PR2#
0J"PSe#
J"PP#
IR n"PE#a
Ib
02[8
01[8
39[7d
31[2e
15[4
15[4
16[3
16[4
29[9
29[7
29[2o
23[9o
29[7o
21[0
21[4o
21[7
24[2
12[5
25[5
12[0
22[5
06[6
22[3
06[7
29[9
04[0
21[5
07[5
20[6
06[8
20[5
07[8
2[2
1[1
IIb
0c
1c
2f
553
369
409
400
373
382
381
368
468
433
470
451
472
459
463l
444n
461
447
468
446
465
451
3[3
1[1
2[7
1[7
3g
4h
5i
6j
09[4k
7m
8
7[7k
27[8\ 29[2
25[6\ 15[9
56[8\ 55[0
56[0\ 51[8
63[2\ 60[3
61[9\ 69[1
09
00
01
02
03
7[4
a EꢁS or Se[
b Taken from Ref[ð06Ł[
c Recorded in CD1Cl1[
d 0H NMR] d 7[88Ð4[20 "arom[ H#[
e 0H NMR] d 8[93Ð4[20 "arom[ H#[
f 0H NMR] d 7[90Ð5[76 "arom[ H#^ 2[75 "CH1#^ 1[54 "NCH2#[
g 0H NMR] d 6[87Ð5[72 "arom[ H#^ 2[76 "CH1#^ 1[52 "NCH2#[
h 0H NMR] d 7[91Ð6[10 "arom[ H#^ 2[13 "NCH2#[
i 0H NMR] d 6[84Ð6[95 "arom[ H#^ 2[04 "NCH2#[
j 0H NMR] d 6[81Ð6[29 "arom[ H#^ 0[54 ð1J"PH# 01[2\ "PCH2#Ł[
k PR2ꢁPMe1Ph[
l n"PdCl#ꢁ295[
m 0H NMR] d 6[83Ð6[29 "arom[ H#^ 0[69 1J"PH# 01[4\ "PCH2#Ł[
n n"PdCl#ꢁ297[
o Tentative assignment only[

Synthesis and conformational studies of palladium"II# complexes
3358
RESULTS AND DISCUSSION
LꢁC8H01N or C01H01N# or ð"Pd"m!Cl#Cl"PMe1Ph##1Ł
gave the neutral complexes ðPd"Ph1P"O#NP"E#Ph1!
O\E!Chelate complexes of ðPh1P"O#NP"E#Ph1Ł− "EꢀS O\E#"LÐL#Ł "EꢁS\ LÐLꢁC8H01N 2^ EꢁSe\ LÐ
or Se#
LꢁC8H01N 3^ EꢁS\ LÐLꢁC01H01N 4^ EꢁSe\ LÐ
LꢁC01H01N 5# and ðPd"Ph1P"O#NP"E#Ph1!
We previously reported the synthesis of the mixed O\E#Cl"PMe1Ph#Ł "EꢁS 6^ EꢁSe 7# in respectable
ligands KðPh1P"O#NP"E#Ph1Ł "EꢁS I^ EꢁSe II# from yields "69Ð85)#[ Compounds 2Ð7 were characterised
the monooxidised compound Ph1P"O#NHPPh1 and by a combination of 20P"0H#\ 0H and IR spectroscopy
elemental sulfur "or selenium# followed by depro! "Table 2# and microanalysis "Table 1#[ In particular\
tonation with base ð06Ł[
d"PO# for 2Ð7 is shifted to lower frequency "ca[ 09Ð
The stoichiometric reaction of ðPdCl1"bipy#Ł 04 ppm# with respect to 0 and 1 and to higher fre!
"bipyꢁ1\1?!bipyridine# and one equivalent of either I quency "ca[ 09Ð04 ppm# with respect to I and II[ The
"or II# in CH2OH\ followed by addition of a meth! 20P"0H# and 0H NMR spectra of 2Ð7 "recorded in
anolic solution of ðNH3ŁðPF5Ł\ gave the cationic com! CDCl2# con_rm that\ in all cases\ only one isomer is
plexes ðPd"Ph1P"O#NP"E#Ph1!O\E#"bipy#ŁPF5 "EꢁS present in solution "either the geometric isomer A or
0^ EꢁSe 1# "Scheme 0#[ Analytical and spectroscopic B#[ X!ray crystallogaphic studies on compounds 5 and
data are given in Tables 1 and 2 and are broadly as 7 "vide infra# unambiguously demonstrate that isomer
expected[ The 20P"0H# NMR spectra of 0 and 1 show\ A "E trans to X where XꢁN\ Cl# is exclusively formed[
in both cases\ two singlet resonances ðJ"PP# coupling The formation of one isomer has also been observed
not resolvedŁ corresponding to PO and PE of the in
the
related
cyclopalladated
complexes
chelating ðPh1P"O#NP"E#Ph1Ł−[ In addition\ the ðPd"Ph1P"O#NPPh1!O\P#"LÐL#Ł
"LÐLꢁC8H01N\
0J"PSe# coupling constant of 369 Hz for 1 is of similar C09H7N\ C01H01N# "P trans to N# ð39Ł but in contrast\
magnitude
to
that
reported
for
cis! both isomers of ðPt"Ph1P"O#NPPh1!O\P#Cl"PMe1Ph#Ł
ðPd"Ph1P"O#NP"Se#Ph1!O\Se#1Ł ð0J"PSe# 381 HzŁ ð06Ł[ have been independently synthesised and fully charac!
Treatment of I "or II# with the chloro bridged terised ð30Ł[ Furthermore in the complexes
binuclear compounds ð"Pd"m!Cl#"LÐL##1Ł "LÐ ðPd"Ph1P"S#NP"Se#Ph1!S\Se#"LÐL#Ł "LÐLꢁC8H01N\
Scheme 0[ "i# ðPdCl1"bipy#Ł\ ðNH3ŁðPF5Ł\ "ii# ð"Pd"m!Cl#"L!L##1Ł "L!LꢁC8H01N or C01H01N#\ "iii# ð"Pd"m!Cl#Cl"PMe1Ph##1Ł\
"iv# ðPdCl1"PR2#1Ł "PR2ꢁPPh2^ 1PR2ꢁPh1PCH1CH1PPh1\ cis!Ph1PCHꢁCHPPh1#\ ðNH3ŁðPF5Ł and "v# ðPdCl1"cod#Ł
"codꢁcycloocta!0\4!diene#[

3369
Alexandra M[ Z[ Slawin et al[
C01H01N# containing di}erent {{soft|| donor centres\ Crystal structure determinations of complexes 5\ 7\ 09\
both isomers were detected in CDCl2 solution in ca[ 01 and 03
4]0 ratio "20P"0H# evidence# ð31Ł[
We have also prepared several square!planar pal!
The structures of 5\ 7\ 09\ 01 and 03 "Table 3\
ladium"II# complexes with one chelating ðPh1P"O#N! Figs 0Ð4# have some common features[ Thus all _ve
P"E#Ph1!O\EŁ− and several di}erent tertiary complexes display the expected square planar
phosphine ligands[ Hence replacement of both geometry "Table 4 gives the maximum deviation from
chloride ligands in ðPdCl1"PR2#1Ł ðPR2ꢁPPh2^ the ML3 co!ordination plane#[ The PdÐP bond lengths
1PR2ꢁPh1PCH1CH1PPh1\ cis!Ph1PCHꢁCHPPh1Ł re~ect the nature of the trans ligand[ Thus in 09\ 01
with one equivalent of I "or II# in CH2OH presumably and 03 Pd"0#ÐP"3# "trans to selenium# is larger than
a}ords
the
cations
ðPd"Ph1P"O#NP"E#Ph1! Pd"0#ÐP"2# "trans to oxygen# suggesting that the Se
O\E#"PR2#1ŁCl[ The cationic compounds were most atom is a poorer s donor:better p acceptor than the
conveniently obtained as their hexa~uorophosphate O atom[ The PdÐSe bond lengths vary ð1[395"0#Ð
salts by metathesis with ðNH3ŁðPF5Ł in CH2OH[ In 1[410"0# AŁ also as a consequence of the trans ligand[
Ä
this manner we have isolated ðPd"Ph1P"O#NP"E#Ph1! The phosphine ligands trans to Se give the largest PdÐ
O\E#"PR2#1ŁðPF5Ł "EꢁS\ PR2ꢁPPh2 8^ EꢁSe\ Se bonds whilst N and Cl give the shortest PdÐSe
PR2ꢁPPh2 09^ EꢁS\ 1PR2ꢁPh1PCH1CH1PPh1 00^ distances which are not distinguishable from each
EꢁSe\
1PR2ꢁPh1PCH1CH1PPh1
01^
EꢁS\ other[ Interestingly the PdÐSe bond lengths in cis!
1PR2ꢁcis!Ph1PCHꢁCHPPh1 02^ EꢁSe\ 1PR2ꢁcis! ðPd"Ph1P"O#NP"Se#Ph!O\Se#1Ł\ with cis O donors\
Ph1PCHꢁCHPPh1 03 "Scheme 0# in good yields[ The "Table 3 and Fig[ 5# are much shorter than any of
in situ reaction between ðPdCl1"Ph1PCH1CH1PPh1#Ł those reported here[ The PdÐO distances are in the
Ä Ä
and
ðPd"Ph1P"O#NP"S#Ph1!O\S#"Ph1PCH1CH1PPh1#ŁCl
I "0]0 ratio# in CH2OH gave exclusively range 1[972"3#Ð1[018"4# A ðc[f[ 1[964"2# and 1[974"2# A
for cis!ðPd"Ph1P"O#NP"Se#Ph!O\Se#1Ł ð06ŁŁ and as
veri_ed by 20P"0H# NMR spectroscopy[ We have also anticipated are less sensitive to the identity of the trans
been able to liberate ðPh1P"O#NP"S#Ph1Ł− "20P NMR atom[ Within the PdÐOÐPÐNÐPÐSe metallacycle the
evidence# by treatment of 00 with concentrated HCl bond lengths are consistent with a fair degree of
ða}ording the parent acid Ph1P"O#NHP"S#Ph1Ł or by delocalisation[
the addition of one equivalent of Ph1PCH1CH1PPh1
The conformation of the PdÐOÐPÐNÐPÐSe rings
ðgiving ðPh1P"O#NP"S#Ph1Ł− and the dication vary somewhat in the various structures[ Compound
ðPd"Ph1PCH1CH1PPh1#1Ł1¦Ł[ Compounds 8Ð03 were 5 has a unique conformation and the ring is best
characterised by 20P"0H# NMR and IR "Table 2 for described as consisting of two planar fragments Pd"0#Ð
data#[ Typically the 20P"0H# NMR data reveal that Se"0#ÐP"0#ÐN"0# and Pd"0#ÐO"0#ÐP"1#ÐN"0# which are
d"PS# for 8\ 00 and 02 is observed at ca[ 21 ppm whilst inclined by 25> with respect to each other[ This di}er!
for 09\ 01 and 03 d"PSe# is around 07 ppm with 0J"PSe# ence in geometry is noticeable in the Pd"0#ÐSe"0#ÐP"0#
ca[ 389 Hz[ Moreover the two inequivalent phos! angle for 5 ð093[57"6#>Ł which lies well outside the
phorus centres of the co!ordinated tertiary phosphines range observed in the other structures including cis!
in 8Ð03 have similar d"P# to those observed in ðPd"Ph1P"O#NP"Se#Ph!O\Se#1Ł ð82[35"5#Ð090[4"3#>Ł[
ðPdCl1"PR2#1Ł[ Consistent with ðPh1P"O#NP"E#Ph1! The conformation in 5 can be described as pseudo!
O\EŁ− chelate formation was the absence of n"PdCl# butter~y and to the best of our knowledge has not
absorptions and the presence of n"PE# absorptions been observed before in ME1P1N systems[ Compound
which in the latter case\ could not accurately be 7 has a ring conformation which\ though rare\ is simi!
assigned with con_dence[
lar to that observed in some previous examples ð06\

Synthesis and conformational studies of palladium"II# complexes
3360
Ä
Table 3[ Selected bond lengths "A# and angles "># for compounds 5\ 7\ 09\ 01 and 03
5
7
09
01
03
ðPd"Ph1P"O#NP"Se#Ph1!O\Se#1Ła
Pd"0#ÐSe"0#
Se"0#ÐP"0#
P"0#ÐN"0#
N"0#ÐP"1#
P"1#ÐO"0#
O"0#ÐPd"0#
Pd"0#ÐC"21#
Pd"0#ÐN"1#
Pd"0#ÐP"2#
Pd"0#ÐCl"0#
Pd"0#ÐP"3#
1[395"0#
1[071"1#
0[463"5#
0[593"5#
0[420"5#
1[018"4#
0[854"7#
1[976"6#
1[398"0#
1[075"1#
0[479"4#
0[483"4#
0[419"3#
1[006"3#
1[346"1#
1[084"3#
0[461"09#
0[590"00#
0[426"8#
1[093"8#
1[410"0#
1[081"1#
0[463"4#
0[487"4#
0[425"3#
1[972"3#
1[382"3#
1[065"6#
0[542"08#
0[448"08#
0[444"08#
1[009"05#
1[270"6#
1[190"0#
0[475"3#
0[592"3#
0[408"2#
1[974"2#
1[272"7#
1[087"1#
0[466"3#
0[473"3#
0[413"2#
1[964"2#
1[100"1#
1[225"1#
1[143"3#
1[243"3#
1[108"1#
1[155"1#
1[113"7#
1[140"7#
Pd"0#ÐSe"0#ÐP"0#
Se"0#ÐP"0#ÐN"0#
P"0#ÐN"0#ÐP"1#
093[57"6#
007[1"2#
015[3"3#
007[0"2#
029[9"2#
88[3"1#
89[8"1#
73[0"2#
74[6"1#
84[25"5#
007[9"1#
020[5"2#
007[0"2#
014[1"2#
81[9"0#
87[5"0#
005[5"4#
014[7"6#
006[0"5#
023[9"4#
85[0"1#
82[35"5#
005[4"1#
012[9"2#
006[9"2#
014[9"1#
87[6"0#
86[7"1#
004[5"7#
013[7"01#
004[7"09#
010[2"09#
099[2"4#
090[4"3#
004[7"0#
012[6"1#
006[3"1#
013[2"1#
88[7"0#
85[5"0#
005[7"1#
021[0"2#
007[1"1#
012[5"1#
80[5"0#
N"0#ÐP"1#ÐO"0#
P"1#ÐO"0#ÐPd"0#
O"0#ÐPd"0#ÐSe"0#
C"21#ÐPd"0#ÐSe"0#
C"21#ÐPd"0#ÐN"1#
N"1#ÐPd"0#ÐO"0#
P"2#ÐPd"0#ÐSe"0#
P"2#ÐPd"0#ÐCl"0#
Cl"0#ÐPd"0#ÐO"0#
P"2#ÐPd"0#ÐP"3#
P"3#ÐPd"0#ÐO"0#
O"0#ÐPd"0#ÐO"1#
Se"0#ÐPd"0#ÐSe"1#
81[28"5#
76[40"6#
78[9"0#
75[4"0#
81[95"5#
76[8"1#
83[8"0#
71[5"2#
73[75"6#
73[6"0#
74[6"2#
74[7"4#
74[7"0#
71[7"0#
a Taken from Ref[ð06Ł[
Fig[ 1[ Core geometry in ðPd"Ph1P"O#NP"Se#Ph1!O\Se#
Cl"PMe1Ph#Ł\ 7[
Fig[ 0[ Core geometry in ðPd"Ph1P"O#NP"Se#Ph1!O\Se#
"C01H01N#Ł\ 5[
and 03 have quite closely related ring conformations
which can be most readily described as pseudo!boat
13Ł with the six!membered ring being hinged about with Se"0# at the prow and P"1# at the stern of the
the O"0# [ [ [ Se"0# vector "hinge angle 59># and the {{boat||[ The Pd"0# [ [ [ P"0# hinge angle in 09\ 01 and
O"0#ÐP"0#ÐN"0#ÐP"1#ÐSe"0# atoms forming an 03 are very similar "ca[ 39># but there are some di}er!
approximate planar array ðmaximum deviation of this ences in the hinge angle at O"0# [ [ [ N"0# "Table 4#[ It
Ä
mean plane is 9[16 A for O"0#Ł[ Compounds 09\ 01 appears that the smallest O"0# [ [ [ N"0# hinge angle is

3361
Alexandra M[ Z[ Slawin et al[
Fig[ 3[ Core geometry in ðPd"Ph1P"O#NP"Se#Ph1!O\Se#
"Ph1PCH1CH1PPh1#ŁðPF5Ł\ 01[
Fig[ 2[ Core geometry in ðPd"Ph1P"O#NP"Se#Ph1!O\Se#
"PPh2#1ŁðPF5Ł\ 09[
Fig[ 5[ Core geometry in cis!ðPd"Ph1P"O#NP"Se#Ph1!O\Se#1Ł
"taken from Ref[ ð06Ł#[
Fig[ 4[ Core geometry in ðPd"Ph1P"O#NP"Se#Ph1!O\Se#"cis!
Ph1PCHꢁCHPPh1#ŁðPF5Ł\ 03[
CONCLUDING REMARKS
We have shown that a range of new palladium"II#
complexes with
a chelating anionic ðPh1P"O#N!
P"E#Ph1Ł− "EꢁS or Se# ligand are ammenable and
have been fully characterised[ Furthermore from X!
ray structure studies it is apparent that the PdÐOÐPÐ
NÐPÐSe six!membered chelate ring is ~exible and can
take up a range of conformations[ Further work into
the generality of these observations would be useful[
for the bulkiest phosphine "PPh2# and this is further
re~ected in the O"0#ÐPd"0#ÐSe"0# angle which
increases in the order 09³01³03 in parallel with the
change in hinge angle[
Overall then\ it appears that the PdSeOP1N ring is
able to adopt a range of geometries and the nature of
the trans ligand does in~uence the geometry within
the metallacycle[
Acknowled`ements*We are grateful to the EPSRC for sup!
port and to Johnson Matthey for loans of precious metals[
Table 4[ Planarity and conformational details in the X!ray structures of 5\ 7\ 09\ 01 and 03
09 01
9[05 ðN"1#Ł 9[18 ðO"0#Ł 9[91 ðO"0#Ł 9[03 ðP"3#Ł 9[06 ðP"3#Ł
5
7
03
Ä
ML3 co!ordination plane "max[ deviation# "A#
Pd"0#ÐSe"0#ÐP"0#ÐN"0#:Pd"0#ÐO"0#ÐP"1#ÐN"0# hinge angle ">#
Pd"0#ÐSe"0#ÐO"0#:Se"0#ÐP"0#ÐN"0#ÐP"1#ÐO"0# hinge angle ">#
Pd"0#ÐP"0#ÐN"0#ÐO"0# "max[ deviation# "A#
Pd"0#ÐSe"0#ÐP"0#:Pd"0#ÐO"0#ÐN"0#ÐP"0# hinge angle ">#
Pd"0#ÐO"0#ÐN"0#ÐP"0#:O"0#ÐP"1#ÐN"0# hinge angle ">#
25
−
−
−
−
−
59
−
−
−
−
−
−
−
−
−
Ä
9[12 ðN"0#Ł 9[10 ðN"0#Ł 9[94 ðN"0#Ł
39
14
32
39
39
37

Synthesis and conformational studies of palladium"II# complexes
3362
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