The preparation and coordination chemistry of substituted benzenethiols. Triphenylphosphine gold(I) complexes of sterically demanding and nondemanding arenethiols. The absence of gold(I)-gold(I) interactions

Article abstract of DOI:10.1016/S0277-5387(98)00339-8

Novel substituted benzenethiols can be easily prepared via aryl thiocyanates or aryl bromides. Reaction of [(Ph₃P)AuCl] with the sterically-nondemanding benzenethiols HSC₆H₄NMe₂-p and HSC₆H₄

Full text of DOI:10.1016/S0277-5387(98)00339-8

\
Polyhedron 07 "0888# 482Ð599
PERGAMON
The preparation and coordination chemistry of substituted
benzenethiols[ Triphenylphosphine gold"I# complexes of sterically
demanding and nondemanding arenethiols[ The absence of gold"I#Ð
gold"I# interactions
Laila S[ Ahmeda\ William Cleggb\ Dominic A[ Daviesa\ 0\ Jonathan R[ Dilworthc\
Mark R[ J[ Elsegoodb\ D[ Vaughan Gri.thsa\ 1\ Lynne Horsburghb\ John R[ Millera\
Nigel Wheatleya\ꢀ
aDepartment of Biological and Chemical Sciences\ University of Essex\ Central Campus\ Wivenhoe Park\ Colchester CO3 2SQ\ U[K[
bDepartment of Chemistry\ University of Newcastle!upon!Tyne\ Newcastle!upon!Tyne NE0 6RU\ U[K[
cInorganic Chemical Laboratory\ University of Oxford\ South Parks Road\ Oxford OX0 2QR\ U[K[
Received 14 May 0887^ accepted 05 September 0887
Abstract
Novel substituted benzenethiols can be easily prepared via aryl thiocyanates or aryl bromides[ Reaction of ð"Ph2P#AuClŁ with
the sterically!nondemanding benzenethiols HSC5H3NMe1!p and HSC5H3NMe¦2!p and with the sterically!demanding benzenethiols
HSCMe1H1NMe1!p\ HSC5Me3H!p and in the presence of triethylamine yields the monomeric gold"I# complexes ð"Ph2P#Au"SAr#Ł\
which are analogous to the gold!based antiarthritic drug Aurano_n[ Reaction with the sterically demanding dithiol HSC5Me3SH!p
in the presence of NEt2 yields the dimeric complex ð""Ph2P#Au#1"m!SC5Me3S!p#Ł[ Spectrochemical and electrochemical data are
reported[ The crystal structures of ð"Ph2P#Au"SC5H3NMe1!p#Ł and ð"Ph2P#Au"SC5H3NMe2!p#ŁPF5 have been solved] both complexes
are monomeric in the solid state\ lacking the short goldÐgold interaction which is commonly found in gold"I# complexes of soft
ligands\ e[g[\ ð"Ph2P#Au"SPh#Ł1[ Þ 0888 Elsevier Science Ltd[ All rights reserved[
Keywords] Gold^ MetalÐmetal interactions^ Cyclic voltammetry^ Thiols
0[ Introduction
albumin cysteine!23 ð3\4Ł[ The exchange of gold between
physiological thiol groups is thought to be important in
its biodistribution and pharmacological activity ð5Ð7Ł[
The phenomenon of {{goldÐgold bonding|| ð8\09Ł\ inter!
action between two d09 gold"I# centres less than the sum
The use of copper and gold to combat connective tissue
disorders dates back to the Bronze Age^ in more modern
times\ gold thiolates are increasingly important in the
control and treatment of arthritis\ especially since the
introduction of the orally!administered drug Aurano_n
ð0\1Ł\ ð"Et2P#Au"SR#Ł "HSRꢁtetraacetylthioglucose#[
The mode of action of gold!based anti!arthritic drugs is
still not well understood ð2Ł\ although it is known that
gold is transported in the blood stream bound to serum
Ä
of the van der Waals radii ð00Ł\ 2[21 A\ has received both
theoretical ð01Ð04Ł and experimental attention ð05Ð16Ł[
The reversible formation of gold"I#Ðgold"I# interactions
in the solid state by a gold dithiocarbamate complex
leads to luminescence in the presence of organic vapours\
o}ering a basis for the detection of volatile organic com!
pounds in the atmosphere ð17Ł[
The energy of these interactions has been estimated to
ꢀ Corresponding author[ Current address] Laboratoire de Catalyse\
be 14Ð29 kJ mol−0 for a goldÐgold distance of 2 A ð18\29Ł\
Ä
Chimie Fine et Polymeres\ Ecole Nationale Superieure de Chimie
Á
ꢂ
de Toulouse\ 007 route de Narbonne\ F!20966 Toulouse cedex 3\
France[ Tel[] ¦22!450!064!581^ fax] ¦22!450!064!599^ e!mail]
nwheatleyÝensct[fr
of the same order of magnitude as hydrogen bonding[
There has been much debate as to the exact nature of the
interaction between the two formally closed!shell centres\
although it is generally agreed that the relativistic con!
traction of the ns orbitals due to the extremely high
angular momentum of the electrons in the gold atom
0 Current address] School of Chemical and Life Sciences\ University
of Greenwich\ Wellington Street\ London SE07 5PF\ UK[
1 Current address] Department of Chemistry\ Queen Mary and West!
_eld College\ Mile End Road\ London\ E0 3NS\ UK[
9166!4276:88:, ! see front matter Þ 0888 Elsevier Science Ltd[ All rights reserved[
PII] S9166!4276 "87#99228!7

483
L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
"Zꢁ68# is an important element of the phenomenon ð20Ð
23Ł[ Recent ab initio studies ð24\25Ł failed to reproduce an
attractive goldÐgold interaction at the HF level\ although
inclusion of electron correlation produced a energy mini!
mum of ca[ 9[90 au "¼14 kJ mol−0# at the MP1 level[ The
energy minimum is quite soft with respect to goldÐgold
distance\ in accordance with the large range of goldÐgold
distances observed ð8\09Ł[
Much of the recent interest in the coordination chem!
istry of sterically!demanding thiols ð26Ł has been directed
at the modelling of active sites in proteins such as fer!
redoxins ð27Ł[ In such complexes\ both the metal centre
and the thiolate anion possess considerable reactivity\
and a degree of steric protection of the sulfur atom is
necessary to allow the isolation of stable complexes[ Most
sterically hindered thiols studied to date have been sub!
stituted with relatively inert carbon! or silicon!based sub!
stituents\ partly due to the limitations on synthetic
procedures based on the NewmannÐKwart rearrange!
ment ð28Ł or chlorosulfonation ð39\30Ł] however\ this has
meant that there has been little attempt to separate the
electronic e}ects of the sterically!demanding substituents
from those caused purely by their size[
re~uxed in methanol for 13 h[ The mixture was allowed
to cool and a small amount of diethyl ether added to
ensure complete precipitation\ yielding trimethyl"3!thio!
cyanatophenyl#ammonium iodide "4[7 g\ 77)# as a yel!
low precipitate[ m[p[ 054>C "from EtOH#[ Found C\ 26[1^
H\ 2[8^ N\ 7[5[ C09H02IN1S requires C\ 26[4^ H\ 3[0^ N\
7[64[ dH "DMSO!d5# 2[4 "8H\ s\ Me#\ 6[8 ð1H\ d\ J"HH#
8[2 Hz\ ArŁ\ 7[1 ð1H\ d\ J"HH# 8[2 Hz\ ArŁ[ dC "DMSO!
d5# 54[3 "s\ Me#\ 009[7 "s\ NCS#\ 011[6 "s\ Ar#\ 016[5 "s\
Ar#\ 029[8 "s\ Ar#\ 036[3 "s\ Ar#[
1[1[ 3!"Trimethylammonio#benzenethiol tetraphenyl!
borate "1#
"Trimethyl "3!thiocyanatophenyl#ammonium iodide#
"1[9 g\ 5[2 mmol# and sodium borohydride "9[36 g\
02 mmol# were re~uxed in methanol "49 ml# for 13 h under
an atmosphere of dry oxygen!free nitrogen[ The mixture
was allowed to cool\ and acidi_ed to pH 5 with 09)
aq[ hydrochloric acid[ The mixture was _ltered\ and a
solution of sodium tetraphenylborate "1[06 g\ 5[2 mmol#
in the minimum quantity of methanol was added\ yielding
3!"trimethylammonio#benzenethiol
tetraphenylborate
"1[1 g\ 61)# as a white precipitate[ m[p[ 062Ð064>C[
Found C\ 79[8^ H\ 5[8^ N\ 1[8[ Calc[ for C22H23BNS C\
70[2^ H\ 6[9^ N\ 1[8[ dH "DMSO!d5# 2[4 "0OH\ s\ Me#\
5[6Ð6[2 "19H\ m#\ 6[34 ð1H\ d\ J"HH# 8[0 Hz\ ArŁ\ 6[53
ð1H\ d\ J"HH# 8[0 Hz\ ArŁ[ dC "DMSO!d5# 45[1 "s\ Me#\
019[8 "s\ Ar#\ 010[5 "s\ BPh3#\ 014[3 "s\ BPh3#\ 017[7 "s\
Ar#\ 024[4 "s\ BPh3#\ 025[1 "s\ Ar#\ 032[7 "s\ Ar#\ 053[3 ðq\
J"CB# 38[5 Hz\ BPh3Ł[ The hexa~uorophosphate salt was
"m[p[ 063Ð066>C ð49Ł# was prepared by an analogous
method[
In a recent paper ð31Ł\ Schmidbaur et al[ compared the
properties of "benzenethiolato#"triphenylphosphine#!
gold"I#\ ð"Ph2P#Au"SPh#Ł\ which exists as a goldÐgold
bonded dimer in the solid!state\ with analogous com!
plexes of sterically!demanding thiols\ which are mono!
meric[ In this paper\ we discuss the synthesis of a number
of sterically!demanding and !nondemanding ben!
zenethiols and their complexation to "triphenyl!
phosphine#gold"I# centres in an attempt to separate the
e}ects of size and electronic properties on the properties
of the complexes\ with particular reference to short
gold"I#Ðgold"I# interactions[
1[2[ 3!Dimethylamino!1\5!dimethylbenzenethiol "2#
3!Dimethylamino!1\5!dimethylphenyl thiocyanate ð40Ł
"0[9 g\ 4[3 mmol#\ sodium sul_de nonahydrate "1[9 g\
15 mmol# and sodium hydroxide "9[14 g\ 5[14 mmol# were
re~uxed in ethanol "14 ml# for 3 h under an atmosphere
of dry oxygen!free nitrogen[ The mixture was allowed to
cool\ and then poured in to a thoroughly degassed 09)
aq[ solution of ammonium chloride "49 ml#[ The mixture
was extracted with degassed diethyl ether "2×04 ml#[ The
ethereal solution was dried over magnesium sulfate and
the solvent removed\ yielding 3!dimethylamino!1\5!
dimethylbenzenethiol[0 dH "CDCl2# 1[3 "5H\ s\ ArÐCH2#\
2[9 "5H\ s\ NÐCH2#\ 2[8 "0H\ s\ SH#\ 5[4 "1H\ s\ ArÐH#[
1[ Experimental
Chloro"triphenylphosphine#gold"I# ð32Ł\ 3!"dimethyl!
amino#benzenethiol ð33Ł and 1\2\4\5!tetramethyl!
benzenethiol ð34\35Ł were prepared by literature methods^
solvents were dried by normal methods ð36Ł\ and distilled
under dry oxygen!free nitrogen prior to use^ all other
chemicals were obtained from normal commercial sour!
ces and used as received[ Microanalyses were performed
by Mr S[ Hodder "University of Essex#[ NMR spectra
were obtained on an JEOL EX!169 spectrometer ð0H
169 MHz\ 02C 56[8 MHz\ standard SiMe3^ 02P 098[2 MHz\
standard 74) H2PO3 "ext[#Ł[
1[3[ 1\2\4\5!Tetramethylbenzene!0\3!dithiol "4#
0\3!Bis"butylthio#!1\2\4\5!tetramethylbenzene
"1[4 g\ 5[5 mmol# was dissolved in liquid ammonia
ð40Ł
1[0[ Trimethyl"3!thiocyanatophenyl#ammonium iodide
"0#
0 The product was usually found to be contaminated with ca[ 19)
bis"3!dimethylamino!1\5!dimethylphenyl#disul_de\ dH "CDCl2# 1[1\ 1[8\
5[3[
3!"Dimethylamino#phenyl thiocyanate ð37\38Ł "5[9 g\
23 mmol# and iodomethane "4[2 ml\ 01[0 g\ 74 mmol# were

L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
484
"099 ml# under an atmosphere of dry oxygen!free nitro!
gen[ Small portions of metallic sodium were added until
a blue colour persisted in the solution for one hour[ Solid
ammonium chloride was added in small portions until
the blue colour was just extinguished[ The ammonia was
allowed to evaporated o}\ leaving a white residue which
was suspended in chloroform "199 ml#[ An excess of dry
hydrogen chloride gas was passed through the suspen!
sion[ The remaining solid was _ltered o}\ and the chloro!
form removed on a rotary evaporator\ giving 1\2\4\5!
tetramethylbenzene!0\3!dithiol "0[2 g\ 87)# as a yellow
solid[ dH "CDCl2# 1[3 "01H\ s\ Me#\ 2[9 "1H\ s\ SH#[ dc
"CDCl2# 08[6 "s\ Me#\ 017[8 "s\ CÐMe#\ 022[2 "s\ CÐSH#[
followed by normal heavy atom procedures\ and re_ned
by the full!matrix least!squares method[ All non!hydro!
gen atoms were re_ned anisotropically\ while hydrogens
were placed in calculated positions[ Atomic coordinates\
interatomic distances and angles\ anisotropic dis!
placement parameters and hydrogen atom positions have
been deposited with the Cambridge Crystallographic
Data Centre\ Cambridge\ with deposition codes 090578
for 5 and 090582 for 6[
2[ Results and discussion
2[0[ Preparation of ligands
1[4[ Gold"I# complexes
Thiocyanation has previously provided a convenient
route to 3!"dimethylamino#benzenethiol ð33\47Ł\ with the
thiocyanate being reduced by either LiAlH3 or sodium
sul_de[ Quaternisation of the amino group does not
appear to interfere with the subsequent reduction\ and so
this method can also be used to prepare the unusual\
electron!de_cient trimethylammonio!substituted ben!
zenethiols[ However\ the initial thiocyanation step is
e}ective only with electron!rich phenyl rings] our
attempts to prepare 0\1\3\4!tetramethyl!2\5!dithio!
cyanatobenzene "03# by this method were unsuccessful[
We were also unable to prepare 1\2\4\5!tetramethyl!
benzene!0\3!disulfonyl dichloride "04# from any of a num!
ber of possible precursors[ Hence we used an adaptation
of the method of Adams and Ferretti ð48Ð50Ł to prepare
1\2\4\5!tetramethylbenzene!0\3!dithiol "durene dithiol#
"4# "see Scheme 0#] this is a signi_cant improvement ð40Ł
in terms of simplicity\ cost and safety over the previous
six!step synthesis of Raasch ð51Ð53Ł[
ð"Ph2P#AuClŁ "9[1 g\ 399 mmol#\ thiol "399 mmol# and
triethylamine "9[93 g\ 309 mmol# were re~uxed in meth!
anol "29 ml# for 2 h under an atmosphere of dry oxygen!
free nitrogen[ Cooling yielded the "triphenyl!
phosphine#gold"I# complex as a white or o}!white pre!
cipitate[ Analytical and other data for the complexes are
given in Tables 0 and 1[
1[5[ Cyclic voltammetry
Measurements were made using a custom!made glass
cell housing the three electrodes and a nitrogen bubbler[
The working and secondary electrode were constructed
from platinum wire fused in glass] a silver reference elec!
trode was also used[ The cell was powered by a EG and
G PAR 251 scanning potentiostat\ and the data recorded
on a 275 microcomputer using the ConDecon program[
Test solutions were approximately 099 mM in complex
and 0999 mM in Bu3N¦BF3! "support electrolyte#] solvents
and results "quoted relative to Cp1Fe:Cp1Fe¦ꢁ9 mV# are
given in Table 2[
2[1[ Preparation of gold"I# complexes
Our gold"I# complexes were stable inde_nitely at room
temperature in the solid state\ in line with the _ndings of
Schmidbaur et al[ ð31Ł and Fackler et al[ ð54Ł and contrary
to the implications of the work of Kowala et al[ ð55\56Ł[
However\ we did notice a small degree of dis!
1[6[ Crystal structure determination
Crystal data and experimental details are given in
Table 3[ The structures were solved by Patterson methods
Table 0
Analyticala and other data for the gold"I# complexes
Complex
Yieldb ")#
dcP:ppm
C
H
N
5 ð"Ph2P#Au"SC5H3NMe1!p#Ł
6 ð"Ph2P#Au"SC5H3NMe2!p#ŁPF5
7 ð"Ph2P#Au"SC5Me1H1NMe1!p#Ł
8 ð"Ph2P#Au"SC5Me3H!p#Ł
66
61
57
69
54
¦28[8
¦28[8d
¦27[6
¦27[8
¦28[9
49[8 "40[0#
31[9 "31[9#
42[6 "42[4#
42[4 "42[7#
38[2 "38[5#
3[04 "3[0#
2[5 "2[6#
3[4 "3[2#
3[6 "3[4#
2[7 "2[7#
1[2 "1[2#
0[7 "0[7#
1[3 "1[1#
09 ð""Ph2P#Au#1SC5Me3S!pŁ
a Required values are given in parentheses[
b Based on ð"Ph2P#AuClŁ[
c 098[2 MHz\ standard 74) aq[ H2PO3 "ext[#\ solvent CDCl2 unless otherwise stated[
d Solvent acetone!d5[

485
L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
Table 1
0H and 02C"0H#!NMRa data for the gold"I# complexes
Com!
NMR!data
pound
5
6
dH 1[8 "5H\ s\ NÐCH2#\ 5[04 ð1H\ d\ J"HH# 7[5 Hz\ ArŁ\ 6[4 "06Hb\ m\ Ar#[
dC 30[1 "s\ NÐCH2#\ 002[5 "s\ C2ÐH#\ 018[2 "s\ C1ÐH#\ 022[4 "s\ CÐS#\ 037[9 "s\ CÐNMe1#[
dcH 2[7 "8H\ s\ NÐCH2#\ 6[5 "08Hb\ m\ Ar#[
dcC 46[6 "s\ NÐCH2#\ 019[8 "s\ C1ÐH#\ 029[6 "s\ C2ÐH#\ 022[2 "s\ CÐS#\ 028[3 "s\ CÐNMe2#[
dH 1[6 "5H\ s\ ArÐCH2#\ 1[8 "5H\ s\ NÐCH2#\ 5[5 "0H\ s\ Ar#[
7
dC 24[0 "s\ ArÐCH2#\ 30[0 "s\ NÐCH2#\ 001[7 "s\ CÐH#\ 028[4 "s\ CÐCH2#\ 033[4 "s\ CÐS#\ 036[7 "s\ CÐNMe1#[
8
dH 1[2 "5H\ s\ C1ÐCH2#\ 1[6 "5H\ s\ C2ÐCH2#\ 5[64 "0H\ s\ Ar#[
dC 19[1 "s\ C1ÐCH2#\ 10[2 "s\ C2ÐCH2#\ 017[1 "s\ CÐH#\ 021[7 "s\ C2ÐCH2#\ 025[8 "s\ C1ÐCH2#\ 028[4 "s\ CÐS#[
dH 1[7 "01H\ s\ ArÐCH2#[
09
dC 11[2 "s\ ArÐCH2#\ 024[5 "s\ CÐS#\ 025[4 "s\ CÐCH2#[
a 0H\ 169 MHz^ 02C\ 56[8 MHz^ standard SiMe3\ solvent CDCl2 unless otherwise speci_ed^ peaks assigned to
triphenylphosphine are not recorded unless otherwise speci_ed[
b Includes 04H corresponding to PPh2[
c Solvent acetone!d5[
Table 2
water "see Scheme 1#[ The irreversibility of this process
Electrochemical dataa for the gold"I# complexes
and the breadth of the peaks in the voltammagrams pre!
vented a quantitative measurement of electron stoi!
chiometry\ although the results are consistent with a two
electron transfer in the case of the dimeric complex 09[
In all the complexes except 6\ there are additional oxi!
dation processes at more positive potentials\ one for 8
and 09 and two for 5 and 7[ These all have coupled
reduction peaks\ although these are much smaller than
the oxidation peaks[ The interpeak spacings and the
observed variation of peak potential with sweep speed
both indicate that the electron transfer in these processes
is very slow\ which may also explain the disparity in peak
currents[
Solvent
CHCl2
Eox
069
E0:1
DE
5
297
480
066
040
6
7
DMSO!d5
CH1Cl1
0122
−003
−204
286
843
134
192
055
105
8
09
CH1Cl1
CH1Cl1
341
163
695
aPotentials
"Cp1Fe:Cp1Fe¦ꢁ¦439 mV vs SCE in THF#[
in
mV
relative
to
Cp1Fe:Cp1Fe¦ꢁ9 mV
proportionation of the complexes of sterically!demand!
ing thiols on attempted recrystallisation\ leading to
deposition of metallic gold[
2[3[ Crystal structures of 5 and 6
¹
Both 5 and 6 crystallise in the triclinic P0 space group\
2[2[ Electrochemistry
with two molecules per unit cell\ related by a centre of
symmetry[ The molecular structures are shown in Figs 0
and 1\ and signi_cant interatomic distances and angles
are given in Tables 4 and 5[ The geometry around the
gold atom is approximately linear\ with PÐAuÐS being
065[42"4#> for 5 and 064[41"3#> for 6[ Perhaps surpris!
ingly\ given the very di}erent electronic properties of the
two thiol phenyl rings\ there is no signi_cant di}erence
The _ve gold complexes showed a complex elec!
trochemistry when studied by cyclic voltammetry[ On the
_rst sweep\ the complexes showed a broad oxidation peak
at −003 to ¦482 mV "see Table 2#\ with the more elec!
tron!rich thiols "e[g[\ 5 and 7# giving the lower values
for the oxidation potential[ No corresponding reduction
peak could be observed\ even on increasing the sweep
speed to 1999 mV s−0 and reducing the temperature to
199 K and the oxidation peak was substantially reduced
in height or even absent in immediately subsequent scans\
indicating an EC!type process\ where an electrochemical
oxidation is immediately followed by a chemical
rearrangement[ This can be explained by an initial trans!
fer of an electron from the complex\ followed by dis!
sociation of a thiyl radical\ which may then dimerise to
form a disul_de or react with the solvent or adventitious
Ä
between the two AuÐS distances^ 1[187"1# A for 5 and
Ä
1[182"2# A for 6[ These distances are within the range of
AuÐS distances observed to date for "tri!
Ä
1[173Ð1[209 A
phenylphosphine#gold"I#
thiolates\
ð2\8\09\31\54\57Ð68Ł] the angles at sulfur\ 093[0"1#> for 5
Ä
and 092[5"1#> for 6 and the AuÐP distances\ 1[148"0# A
Ä
for 5 and 1[148"2# A for 6\ are also typical for this type
of complex[
The most striking feature of these crystal structures is
the absence of any short gold"I#Ðgold"I# interaction\ with

L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
486
Table 3
Crystal data and experimental details of the structure determinations for 5 and 6
5
6
Colour and habit
Crystal dimensions "mm#
Formula
orangeÐbrown tablets
9[4×9[5×0[9
C15H14AuNPS
pale blue tablets
9[31×9[02×9[09
C16H17AuNPS = PF5
¹
¹
Space group
P0 "No[ 1#
P0 "No[ 1#
Ä
a "A#
8[6493"6#
09[823"1#
02[2761"8#
68[429"7#
57[823"5#
7[541"8#
Ä
b "A#
09[533"01#
04[607"06#
76[41"8#
76[56"6#
63[11"01#
Ä
c "A#
a ">#
b ">#
g ">#
54[257"8#
0198[7"1#
2
Ä
U "A #
0280"2#
Z
1
1
Di}ractometer
Radiation
Enraf!Nonius CAD3
MoÐKa
StoeÐSiemens ð44Ł
MoÐKa
Re~ections measured
Unique re~ections
Observed re~ections
Transmission factors
Re_nement
3139 "0[4²u²14#
3139
4064 "1[5²u²14#
3781
2891 ðF×2s"F#Ł
max 0[9\ min 9[68
F
3536 ðF×1s"F#Ł
max 9[349\ min 9[117
F1
Weighting scheme "w−0
#
s1"Fo#¦9[9993F1o
s1"F1o#¦1[5282P¦9[9911P1
ðPꢁ"F1o¦1F1c#:2Ł
0[960
Agreement analysis "S#
Final R
0[75
9[920
9[9145
Final R?
9[934
9[9619
Program
Molen ð45Ł
SHELXTL ð46Ł
the thiolate rings of 5 was investigated\ as the rings are
parallel^ however\ the closest approach is
C"01# = = = C"01?#ꢁ2[49"0# A[
Ä
Short goldÐgold interactions have been observed in a
wide range of gold"I# compounds ð8\09Ł\ including
ð"Ph2P#Au"SPh#Ł1 "05# ð31\68Ł and ð"Ph2P#Au"C2CPh#Ł1
ð79Ł[ It has been proposed that the tendency to form
goldÐgold bonds increases with the softness of the ligand
ð8\09\70\71Ł\ and hence we would de_nitely expect 5 to
show such
a short contact\ as the 3!"dimethyl!
amino#benzenethiolato ligand is softer than the ben!
zenethiolato ligand in 05[
However\ many gold"I# complexes of the type ðLAuXŁ\
where X is a soft anionic ligand such as iodide\ exist as
chains or clusters of distinct anions and cations\
ðL1AuŁðAuX1Ł\ in the solid state ð8\09\72Ð76Ł[ It would be
expected that any goldÐgold interactions in these com!
pounds would be enhanced by the Coulombic attraction
between the ions\ although recent ab initio studies indicate
that the electron populations on the gold centres in the
two isomeric forms\ ðLAuXŁ1 and ðL1AuŁ¦ðAuX1Ł−\ as
well as their total energies\ are very similar ð77Ł[
Scheme 0[
Ä
minimum Au = = = Au distances of 5[070 A for 5 and
4[516 A for 6[ The possibility that a goldÐgold interaction
might be overtaken by a stacking interaction between
Ä
Schmidbaur et al[ ð31Ł have postulated that the steric
demands of the thiol ligand prevent goldÐgold inter!
Scheme 1[

487
L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
Fig[ 0[ The molecular structure of ð"Ph2P#Au"SC5H3NMe1!p#Ł[
Fig[ 1[ The molecular structure of the ð"Ph2P#Au"SC5H3NMe2!p#Ł¦ cation[
actions in ð"Ph2P#Au"SC5R2H1#Ł "RꢁMe\ Et\ Pri#\ despite
the bending of the phenyl ring away from any obstacle
"AuÐSÐC 090[6Ð009[7># and the softer nature of the thiol
ligands compared to the benzenethiolato ligand[ This
explanation for the absence of short goldÐgold contacts
has been applied in other systems ð54\78\89Ł[ However\ in
neither 5 nor 6 is the arenethiolate ligand signi_cantly
more sterically demanding than that in 05[
The long Au [ [ [ Au distances in 5 and 6 cannot be
explained in terms of ligand softness or steric demands[
Hence we are forced to conclude that explanations of the
existence or absence of short gold"I#Ðgold"I# contacts
which are based on the softness or steric demands of
the anionic ligand are at best incomplete\ and that such
contacts should be viewed as just one of the many inter!
molecular interactions which occur to stabilise a crystal[

L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
ð6Ł Isab AA\ Sadler PJ[ J[ Chem Soc Dalton Trans[ 0871^024[
488
Table 4
Ä
Signi_cant interatomic distances "A# and angles "># for ð"Ph2P#Au!
"SC5H3NMe1!p#Ł "5#] _gures in parentheses indicate the estimated stan!
dard deviation in the least signi_cant digit
ð7Ł Snyder RM\ Mirabelli CK\ Crooke ST[ Biochem Pharmacol
0875^24]812[
ð8Ł Ahrland S\ Dreisch K\ Noren B\ Oskarsson A[ Mat Chem Phys
ꢂ
Ä
0882^24]170[
Complex
Distance or
angle "A or >#
Complex
Distance or
angle "A or >#
ð09Ł Pyykko P[ Chem Rev 0886^86]486[
ð00Ł Bondi A[ J[ Phys Chem 0853^57]330[
Ã
Ä
Ä
ð01Ł Jiang Y\ Alvarez S\ Ho}mann R[ Inorg Chem 0874^13]638[
AuÐP
PÐC"10#
PÐC"20#
1[148"0#
0[705"4#
0[707"4#
AuÐS
SÐC"00#
PÐC"30#
1[187"1#
0[652"5#
0[797"4#
ð02Ł Pyykko P\ Runeberg N\ Mendizabal F[ Chem Eur J 0886^2]0340[
ð03Ł Pyykko P\ Mendizabal F[ Chem Eur J 0886^2]0347[
Ã
Ã
ð04Ł Pyykko P\ Mendizabal F[ Inorg Chem 0887^26]2907[
Ã
ð05Ł Balch AL\ Fung EY\ Olmstead MM[
0889^001]4070[
ð06Ł King C\ Wang J!C\ Khan MNI\ Fackler Jr JP[ Inorg Chem
0878^17]1034[
ð07Ł Tzeng BC\ Che CM\ Peng SM[ J[ Chem Soc Dalton Trans
0885^0658[
J Am Chem Soc
PÐAuÐS
C"10#ÐPÐAu
C"30#ÐPÐAu
065[42"4#
004[3"1#
002[2"1#
C"00#ÐSÐAu
C"20#ÐPÐAu
C"10#ÐPÐC"20# 095[1"1#
C"20#ÐPÐC"30# 094[3"1#
093[0"1#
009[4"1#
C"10#ÐPÐC"30# 094[2"1#
ð08Ł Tang SS\ Lin IJB\ Liu LS\ Wang JC[ J Chin Chem Soc 0885^32]216[
ð19Ł Colacio E\ Cuesta R\ Gutierrez!Zorilla JM\ Luque A\ Roman P\
Giraldi T\ Taylor MR[ Inorg Chem 0885^24]3121[
ð10Ł Cerrada E\ Jones PG\ Laguna A\ Laguna M[ Inorg Chim Acta
0885^138]052[
Table 5
Ä
Signi_cant interatomic distances "A# and angles "># for ð"Ph2P#Au!
"SC5H3NMe2!p#ŁPF5 "6#] _gures in parentheses indicate the estimated
standard deviation in the least signi_cant digit
ð11Ł Toronto DV\ Weissbart B\ Tinbi DS\ Balch AL[ Inorg Chem
0885^24]1373[
ð12Ł Van Calcar PM\ Olmstead MM\ Balch AL[ Inorg Chem
0886^25]4120[
Complex
Distance or
angle "A or >#
Complex
Distance or
angle "A or >#
Ä
Ä
ð13Ł Xiao H\ Weng YX\ Wong WT\ Mak TCW\ Che CM[ J Chem Soc
Dallon Trans 0886^110[
ð14Ł Feng DF\ Tang SS\ Liu CW\ Lin IJB[ Organometallics
0886^05]890[
AuÐP"0#
P"0#ÐC"6#
P"0#ÐC"0#
1[148"2#
0[703"3#
0[703"4#
AuÐS
SÐC"08#
PÐC"02#
1[182"2#
0[667"4#
0[710"4#
ð15Ł Tang SS\ Chang CP\ Lin IJB\ Liou LS\ Wang JC[ Inorg[ Chem
0886^25]1183[
ð16Ł Vincente J\ Chicote MT\ Abrisqueta MD\ Guerrero R\ Jones PG[
Angew[ Chem Int[ Ed[ Engl 0886^25]0192[
ð17Ł Mansour MA\ Connick WB\ Lachicoue RJ\ Gysling HJ\ Eisenberg
R[ J Am Chem Soc 0887^019]0218[
P"0#ÐAuÐS
C"0#ÐP"0#ÐAu
C"6#ÐP"0#ÐAu
064[41"3#
004[7"1#
003[7"1#
C"08#ÐSÐAu
092[5"1#
C"02#ÐP"0#ÐAu 096[2"1#
C"0#ÐP"0#ÐC"02# 096[4"1#
C"6#ÐP"0#ÐC"02# 095[0"1#
C"6#ÐP"0#ÐC"0# 093[7"1#
ð18Ł Schmidbaur H\ Graf W\ MuÃller G[ Angew[ Chem Int Ed Engl
0877^16]306[
ð29Ł Dziwok K\ Lachmann J\ Wilkinson DL\ Muller G\ Schmidbaur
Ã
Acknowledgements
H[ Chem Ber 0889^012]312[
ð20Ł Raptis RG\ Fackler Jr JP\ Murray HH\ Porter LC[ Inorg Chem
0878^17]3946[
ð21Ł Pyykko P[ Chem Rev 0877^77]452[
Ã
The authors would like to thank Mr[ N[ L[ Barnard
"University of Essex# for his help in conducting the elec!
trochemical experiments\ Johnson Matthey for their gift
of sodium tetrachloroaurate\ and the following for stu!
dentships during the period of this work] European Social
Fund "LSA#\ London Borough of Bromley "DAD#\ B[ P[
Chemicals Ltd[ "NW#[ The authors also thank Professor
Pekka Pyykkoà "University of Helsinki#\ as well as one of
the reviewers of the original submission\ for bringing to
our attention certain published articles[
ð22Ł Pitzer KS[ Acc Chem Res 0868^01]160[
ð23Ł Pyykko P\ Desclaux JP[ Acc Chem Res 0868^01]165[
Ã
ð24Ł Pyykko P\ Zhao Y[ Angew[ Chem Int Ed Engl 0880^29]593[
Ã
ð25Ł Li J\ Pyykko P[ Chem Phys Lett 0881^086]475[
Ã
ð26Ł Dilworth JR\ Hu J[ Adv Inorg Chem 0883^39]300[
ð27Ł Krebs B\ Henkel G[ Angew Chem Int[ Ed[ Engl 0880^29]658[
ð28Ł Newman MS\ Karnes HA[ J Org Chem 0855^20]2879[
ð39Ł Huntress EH\ Autenrieth JS[ J Am Chem Soc 0830^52]2335[
ð30Ł Blower PJ\ Dilworth JR\ Hutchinson J\ Nicholson T\ Zubieta JA[
J Chem Soc Dalton Trans 0874^1528[
ð31Ł Nakamoto M\ Hiller W\ Schmidbaur H[ Chem Ber 0882^015]594[
ð32Ł Jones AG\ Powell DB[ Spectrochim[ Acta Part A 0863^29]452[
ð33Ł Chuchani G\ Frohlich A[ J Chem Soc B 0860^0306[
ð34Ł Kuliev AM\ Kyazim!Zade AK\ Guseinov KZ[ Zh Org Khim
0869^5]0702 Chem Abstr 0869\ 62\ 019125k[
ð35Ł Leonardi A\ Rossi S\ Palmeri C\ Nardi D\ Subissi A[ Boll Chim
Farm 0868^007]175^ Chem Abstr 0879^81]58359s[
ð36Ł Perrin DD\ Armarego WLF[ Puri_cation of Laboratory Chemi!
cals\ 2rd ed[ Oxford] Pergamon\ 0877[
ð37Ł Brewster RQ\ Schroeder W[ Org Synth 0828^08]68[
ð38Ł Brewster RQ\ Schroeder W[ Org Synth\ 1nd Coll[ Vol[\ 463[
ð49Ł DePamphilis BV\ Averill BA\ Herskovitz T\ Que L Jr\ Holm RH[
J Am Chem Soc 0863^85]3048[
References
ð0Ł Sutton BM\ Gusty E\ Walz DT\ DiMartino MJ[ J[ Med[ Chem
0861^04]0984[
ð1Ł Hill DT\ Sutton BM[ Cryst Struct Commun 0879^8]568[
ð2Ł Brown DH\ Brown WE[ Chem Soc Rev 0879^8]106[
ð3Ł Shaw III CF\ Schae}er NA\ Elder RC\ Eidsness MK\ Trooster
JM\ Calis GHM[ J Am Chem Soc 0873^095]2400[
ð4Ł Co}er MT\ Shaw III CF\ Eidsness MK\ Watkins II JW[ Inorg[
Chem 0875^14]22[
ð5Ł Shaw III CF\ Co}er MT\ Kingbeil J\ Mirabelli CK[ J Am Chem
Soc 0877^009]618[
ð40Ł Davies DA[ B[Sc[ dissertation\ University of Essex 0883[

599
L[S[ Ahmed et al[ : Polyhedron 07 "0888# 482Ð599
ð41Ł Adams R\ Reifschneider W\ Ferretti A[ Org Synth 0851^31]11[
ð42Ł Adams R\ Reifschneider W\ Ferretti A[ 4th Coll[ Vol[\ 096[
ð43Ł Adams R\ Ferretti A[ J Am Chem Soc 0848^70]3816[
ð45Ł Fair CK[ MOLEN\ An Interactive Structure Solution Procedure[
Enraf!Nonius\ Delft 0889[
ð44Ł Clegg W[ Acta Crystallogr Sect A 0870^26]11[
ð45Ł SHELXTL "version 4#[ Siemans Analytical X!ray Instruments\
Madison\ WI 0884[
ð47Ł Ban_eld JE[ J Chem Soc 0859^345[
ð48Ł Adams R\ Ferretti A[ J Am Chem Soc 0848^70]3828[
ð59Ł Ferretti A[ Org Synth 0851^31]43[
ð50Ł Ferretti A[ Org Synth\ 4th Coll[ Vol[ 308[
ð51Ł Raasch MS[ J Org Chem 0868^33]1518[
ð52Ł Smith LI\ Dobrovolny FJ[ J Am Chem Soc 0815^37]0319[
ð53Ł Conant JB\ Fieser LF[ J Am Chem Soc 0812^34]1083[
ð54Ł Forward JM\ Bohmann D\ Fackler JP\ Staples RJ[ Inorg Chem
0884^23]5229[
ð55Ł Coates GE\ Kowala C\ Swan JM[ Aust J Chem 0855^08]428[
ð56Ł Kowala C\ Swan JM[ Aust J Chem 0855^08]436[
ð57Ł Hoskins BF\ Lu Z\ Tiekink ERT[ Inorg Chim Acta 0878^047]6[
ð58Ł Kuz|mina LG\ Smislova EI\ Grandberg KI[ Zh Neorg Khim
0882^27]0998[
ð61Ł Sladek A\ Schmidbaur H[ Chem Ber 0884^017]896[
ð62Ł Viotte M\ Gautheron B\ Nifantev I\ Kuz|mina LG[ Inorg Chim
Acta 0885^142]60[
ð63Ł Schneider W\ Bauer A\ Schmidbaur H[ Organometallics
0885^04]4334[
ð64Ł Sladek A\ Schmidbaur H[ Inorg Chem 0885^24]2157[
ð65Ł Sladek A\ Schneider W\ Angermeier K\ Bauer A\ Schmidbaur H[
Z[ Naturforsch[ B Chem Sci 0885^40]654[
ð66Ł Bishop P\ Marsh P\ Brisdon AK\ Brisdon BJ\ Mahon MF[ J Chem
Soc Dalton Trans 0887^564[
ð67Ł Onaka S\ Katsukawa Y\ Yamashita M[ Chem Lett 0887^414[
ð68Ł Fackler JP\ Staples RJ\ Elduque A\ Grant T[ Acta Crystallogr[
Sect[ C 0878^34]419[
ð79Ł Schmidbaur H\ Weidenhiller G\ Steigelmann O\ Muller G[ Chem
Ã
Ber 0889^012]174[
ð70Ł Pyykko P\ Li J\ Runeberg N[ Chem Phys Lett 0883^107]022[
Ã
ð71Ł Abraham SP\ Samuelson AG[ Proc Indian Acad Sci 0885^097]020[
ð72Ł Adams H!N\ Hiller W\ Strahle J[ Z Anorg Allg Chem 0871^374]70[
Ã
ð73Ł Conzelmann W\ Hiller W\ Strahle J\ Sheldrick GM[ Z Anorg Allg
Ã
Chem 0873^401]058[
ð74Ł Ahrland S\ Noren B\ Oskarsson A[ Inorg Chem 0874^13]0229[
ꢂ
Ä
ð75Ł Wang S\ Fackler Jr JP[ Inorg Chem 0889^18]3393[
ð76Ł Bauer A\ Schmidbaur H[ J Am Chem Soc 0885^007]4213[
ð69Ł Narayanaswamy R\ Young MA\ Parlhurst E\ Ouellette M\ Kerr
ME\ Ho DM\ Elder RC\ Bruce AE\ Bruce MRM[ Inorg Chem
0882^21]1495[
ð60Ł Tong YY\ Pombeiro AJL\ Hughes DL\ Richards RL[ Transition
Met[ Chem "London# 0884^19]261[
ð77Ł Pyykko P\ Schneider W\ Bauer A\ Bayler A\ Schmidbaur H[ Chem
Ã
Commun 0886^0000[
ð78Ł Angermaier K\ Schmidbaur H[ Chem Ber 0883^016]1276[
ð89Ł Bauer A\ Schneider W\ Angermaier K\ Schier A\ Schmidbaur H[
Inorg Chim Acta 0885^140]138[