Spectroscopic properties, structure and reactivity of [WCl(SnCl3)(CO)3(NCMe)2]

Article abstract of DOI:10.1016/S0277-5387(98)00123-5

A series of seven-coordinate tungsten(II) nitrile complexes of the type [WCl(SnCl₃)(CO)₃(NCR)₂](1-4), R=Me, Et, n-Bu, Ph, has been synthesized. These new complexes have been characterized by IR, NMR and UV-vis spectroscopy. In addition single-crystal X-ray diffraction was used to structurally characterize [WCl(SnCl₃)(CO)₃(NCMe)₂](1). The most prominent feature of complex 1 is the facility by which acetonitrile and carbonyl ligands can be replaced by other ligands. Complexes were isolated in which CO and acetonitrile ligands were substituted by alkyne ligands. The alkyne tungsten(II) complexes 5-8 formed were structurally characterized by IR and NMR spectroscopy. The complex 1 has been found to be an active catalyst for the polymerization of phenylacetylene. The structures and mechanisms of the formation of various new types of complexes and their role in the catalytic process are discussed.

Full text of DOI:10.1016/S0277-5387(98)00123-5

Polyhedron Vol[ 06\ No[ 08\ pp[ 2308Ð2315\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99012Ð4
Spectroscopic properties\ structure and reactivity
of ðWCl"SnCl2#"CO#2"NCMe#1Ł
Teresa Szymanska!Buzarꢁ and Tadeusz G<owiak
ꢀ
Faculty of Chemistry\ University of Wroc<aw\ 03 F[Joliot!Curie\ 49!272 Wroc<aw\ Poland
"Received 02 February 0887^ accepted 14 March 0887#
Abstract*A series of seven!coordinate tungsten"II# nitrile complexes of the type ðWCl"SnCl2#"CO#2"NCR#1Ł"0Ð
3#\ R Me\ Et\ n!Bu\ Ph\ has been synthesized[ These new complexes have been characterized by IR\ NMR
1
and UV!vis spectroscopy[ In addition single!crystal X!ray di}raction was used to structurally characterize
ðWCl"SnCl2#"CO#2"NCMe#1Ł"0#[ The most prominent feature of complex 0 is the facility by which acetonitrile
and carbonyl ligands can be replaced by other ligands[ Complexes were isolated in which CO and acetonitrile
ligands were substituted by alkyne ligands[ The alkyne tungsten"II# complexes 4Ð7 formed were structurally
characterized by IR and NMR spectroscopy[ The complex 0 has been found to be an active catalyst for the
polymerization of phenylacetylene[ The structures and mechanisms of the formation of various new types of
complexes and their role in the catalytic process are discussed[ Þ 0887 Elsevier Science Ltd[ All rights reserved
Keywords] tungsten^ tin^ crystal structure^ nitrile complexes^ alkyne complexes^ polymerization of phenyl!
acetylene[
———————————————————————————————————————————————
A number of seven!coordinated compounds with a
The unknown coordination geometry of ace!
tungsten!tin or a molybdenum!tin bond have been tonitrile compound 0 together with the fact that com!
prepared by reaction of tungsten! and molybdenum! pounds of this class have been used for synthetic
substituted carbonyls\ ðM"CO#3L1Ł "1Lꢂ1\1?!bipy! purpose on several occasions ð09Ð06Ł\ make it an inter!
ridyl\
phino#ethane\ RN
1\4!dithiahexane\
CHCH
0\1!bis"diphenylphos! esting problem for X!ray structure analysis[
NR\ Rꢂi!Pr\ n!Bu or
1
1
Cy\ two molecules of acetonitrile# and tin tetrahalides
or organometallic halides\ RnSnCl3!n\ R Me\ Bu\ Ph
EXPERIMENTAL
1
ð0Ð09Ł[ Among them acetonitrile compounds are
especially interesting as useful starting materials in
which the labile acetonitrile groups can be easily
replaced by other ligands ð09Ð06Ł[ This can be the basis
for synthetic procedures\ including the preparation of
alkene and alkyne derivatives as well as a model of a
All operations were carried out in an inert atmo!
sphere using standard Schlenk techniques[ All solvents
and liquid reagents were dried and distilled over CaH1[
IR spectra "KBr pellets# were recorded on an FT!
IR Model!399 Nicolet instrument and Far!IR spectra
"499Ð49 cm−0# were recorded with a Brucker IFSv
Ã
catalytic
centre[
In
the
reaction
of
0
instrument in Nujol mull on a polyethylene _lm[ H
ðWCl"SnCl2#"CO#2"NCMe#1Ł"0# with norbornadiene
two acetonitrile ligands are replaced by one molecule
of norbornadiene and ðWCl"SnCl2#"CO#2"h3!NBD#Ł is
formed ð06Ł[ In this paper we present results con!
cerning the reactivity of complex 0 towards alkynes[
Complexes were isolated in which CO and acetonitrile
ligands were replaced by alkyne ligands[ The complex
0 has been found to be an active catalyst for the
polymerization of phenylacetylene[
and 02C"0H# NMR spectra were run using a Bruker
AMX!299 spectrometer[ UV!visible absorption spec!
tra were recorded on a HewlettÐPackard 7341A spec!
trophotometer[ The analysis of the catalytic reaction
products was performed on a HewlettÐPackard GC!
MS system and by 0H NMR spectroscopy[
Synthesis of ðWCl"SnCl2#"CO#2"NCMe#1Ł"0#
To ðW"CO#3"NCMe#1Ł ð07Ł "0[7 g\ 3[6 mmol# dis!
solved in CH1Cl1 "49 cm2# with continuous stirring
ꢁ Author to whom correspondence should be addressed[
2308

2319
T[ Szymanska!Buzar and T[ G<owiak
ꢀ
under a stream of nitrogen\ was added a stoi! di}erent isomers of diphenylbutadienes "08)#\ and a
chiometric amount of SnCl3 "9[45 cm2\ 3[6 mmol# by dimer of PA detected by MS as 0H!indene!0!"phe!
means of a syringe[ The mixture was stirred for 5 nylmethylene# "0)#[
hours\ during which time the yellow solution gradu!
ally changed to an orange colour\ while the n"CO#
Procedures for testin` catalytic activity and charac!
frequency of ðW"CO#3"NCMe#1Ł disappeared[ After
terization of or`anic products
the completion of the reaction\ the solution was sep!
arated from some insoluble blue powder by _ltration
Polymerization experiments were carried out in a
and evaporated to dryness[ The crystallization from
reaction mixture composed of toluene or CH1Cl1 as
CH1Cl1:heptane produced the analytically pure dark
solvent\ ortho!xylene "the internal chromatographic
orange crystalline complex 0 "Table 0#[
standard#\ phenylacetylene "PA#"0 mol dm−2#\ and
complex 0"PA:W 099#[ The reaction mixture was stir!
red by a magnetic stirrer at room temperature in a
49 cm2 glass reactor provided with a septum through
which liquid reactants were introduced and removed
by a syringe[ The gas!samples were removed with a
syringe and injected into the PORA PLOT!Q 04 m
column of the chromatograph _tted with a ~ame ion!
ization detector[ The conversion of PA\ monitored by
chromatography\ was not higher than 09) after 13 h
reaction[ For the analysis of PA reaction products\
reactions were continued for 13 h and then methanol
was added[ The polymer "PPA# was collected\ washed
with methanol\ dried and weighed[ The poly!
merization yield ")# is de_ned by comparing the poly!
mer weight to the weight of the PA used and 13 h
reaction catalyzed by 0 was about 6)[ The polymer
Preparation
"R1C1H4#^ 2 "R
of
ðWCl"SnCl2#"CO#2"NCR#1Ł\
C5H4#[
1
1
C2H6#^ 3 "R
1
0 was dissolved in an appropriate nitrile and the
solution was stirred for 59 min[ Filtration\ followed
by removal of the solvent in vacuo\ gave a residue
coloured from orange 1 to red 3\ which was recrys!
tallized from CH1Cl1!heptane giving a pure crystalline
bis"nitrile# complex 1!3 "Table 0#[
Reaction of 0 with PhC2CPh
To a solution of 0 "9[1 g\ 9[22 mmol# in 04 cm2 of
CH1Cl1 was added PhC2CPh "9[01 g\ 9[55 mmol# in
4 cm2 of CH1Cl1[ The mixture was stirred for two
hours\ after which time the full conversion of 0 was
observed by IR[ Evaporation of the solvent followed
by washing with heptane produced a mixture of com!
pounds identi_ed by IR and NMR studies as
0
was analysed by H NMR\ IR spectroscopy and gel!
permeation chromatography[ Molecular weights of
the PPA were measured using CHCl2 solutions\ a
refractive index monitor and a Plgel 09 m MIXED!B
column[ The value recorded "Mwꢂ4×092# is the
weight of polystyrene that would exhibit the chro!
matogram observed[
ðWCl1"CO#"NCMe#"PhC2CPh#1Ł
ðWCl1"NCMe#1"PhC2CPh#1Ł
4\
and
5
"Table 1#[ Crys!
tallization of the above greenish!yellow solid from
CH1Cl1:heptane always produced mixture of the com!
pounds 4 and 5\ but with di}erent molar ratios
depending on reaction time[ Beside 4 and 5\ a side
products were formed[ One was identi_ed by IR]
n"CO# 1958 "vw#\ 0828 "vs# and 02C NMR] d 191[36 "0
CO#\ 085[43 "3 CO# ppm as ðW"CO#4SnCl1Ł and other
was separated by _ltration as white\ insoluble in
CH1Cl1 solid of SnCl1[
The _ltrate obtained after the precipitation of the
polymers was evaporated to dryness and the CH1Cl1
solution of the residue was investigated by GC!MS
"HP4 14 m column#[ Analysis showed 0\1\3!tri!
phenylbenzene "34)#\ 0\2\4!triphenylbenzene "23)#\
di}erent isomers of diphenylbutadienes "05)#\ and a
dimer of PA detected by MS as 0H!indene!0!"phe!
nylmethylene# "4)#[
0H NMR spectra of the polymers were recorded in
a CDCl2 solution at 299 MHz[ The microstructural
0
details of the polymers were deduced from the H
Reaction of 0 with phenylacetylene "PA#
NMR integrals ð08Ł as mainly trans[
A slight excess of PA "9[014 cm2\ 0[07 mmol# was
syringed into a stirred CH1Cl1 solution "04 cm2# of 0 Crystallo`raphy
"9[1 g\ 9[22 mmol# at room temperature[ Immediately
the solution became dark orange[ Stirring for 1 hours
Crystal data for 0[ C6H5Cl3N1O2SnW\ Mꢂ509[37\
followed by the evaporation of the solvent under low monoclinic\ space group P10:m\ aꢂ5[792"0#\
Ä
pressure gave an orange solid\ which was washed out bꢂ02[558"2#\
with a small portion of heptane and dried in vacuo to Uꢂ672[8"2# A \
cꢂ7[539"1# A\
bꢂ091[57"2#>\
Dcꢂ1[475 g cm−2
The dark
2
Ä
Zꢂ1\
\
give a greenish yellow mixture of compounds con! F"999#ꢂ445\ m"Mo!Ka#ꢂ85[93 cm−0
[
taining mainly ðWCl1"CO#"NCMe#"PhC2CH#1Ł 6 orange crystals of 0 were grown from a CH1Cl1:to!
and ðWCl1"NCMe#1"PhC2CH#1Ł 7 as was shown by luene:heptane solution[ The crystals were stable
0H and 02C"0H# NMR spectra "Table 1#[ The heptane enough when handled in an inert atmosphere or
extract contained organic products] 0\1\3!tri! coated with a light hydrocarbon oil to protect them
phenylbenzene "30)#\ 0\2\4!triphenylbenzene "28)#\ from the atmosphere[ Crystallographic data were

Table 0[ Spectroscopic data for the seven!coordinate nitrile complexes ðWCl"SnCl2#"CO#2"NCR#1Ł 0Ð3^ R1CH2 "0#\ C1H4 "1#\ C2H6 "2#\ C5H4 "3#
IR"n\ cm−0
#
0H NMR
02C"0H# NMR
"d\ ppm^ J\ Hz#
UV!vis\ l\ nm
n"CO#a
n"CN#a
n"SnCl#b
"d\ ppm^ J\ Hz#
1[42 "s\ 1 CH2CN#c
"e\ dm2 mol−0 cm−0
Complex
0
1929 "vs#
1216 "w#
0824 "s\sh# 1188 "w#
0892 "vs#
233 "w#
214 "w#
100[82 "s\ 2 CO#\ 015[79 "s\ 1 CH2CN#\ 3[43 "s\ 1
CH2CN#c
149 "8275#\
189 "3114#\
287 "353#d
1
2
1911 "vs#
0825 "s\sh#
0896 "vs#
1910 "s#
1182 "m#
1181 "m#
1[71 "q\ JHHꢂ6[4\ 1 CH2CH1CN# 0[35 "t\ JHHꢂ6[4\ 1
CH2CH1CN#e
100[90 "s\ 2 CO#\ 018[36 "s\ 1 CH2CH1CN#\ 01[64 "s\
1 CH2CH1CN#\ 8[34 "s\ 1 CH2CH1CN#e
1
1
1[79 "t\ JHHꢂ6[9\
1 CH2CH1CH1CN# 0[78 "q\ 100[16 "s\ 2 CO\ JWCꢂ014\ J006SnÐ02Cꢂ150\ J008SnÐ
0839 "s\sh#
0804 "vs#
JHHꢂ6[4\ 1 CH2CH1CH1CN# 0[03 "t\ JHHꢂ6[4\ 1 02Cꢂ166# 017[83 "s\ 1 CH2CH1CH1CN#\ 19[38 "s\ 1
CH2CH1CH1CN#e
CH2CH1CH1CN#\ 07[59 "s\ 1 CH2CH1CH1CN#\ 02[37
"s\ 1 CH2CH1CH1CN#e
100[98 "s\ 2 CO\ JWCꢂ016\ J006SnÐ02Cꢂ156\ J008SnÐ
02Cꢂ179# 024[87 "s\ CpÐ!Ph# 022[50 "s\ CoÐ!Ph# 018[73
"s\ CmÐ!Ph# 018[94 "s\ CiÐ!Ph# 015[82 "s\ 1 PhCN#\e
0
1
1
3
1915 "s#
0834 "s#
0801 "s#
1152 "m#
6[75 "d\ o!Ph\ Jꢂ6[2# 6[67 "t\ p!Ph\ Jꢂ6[6# 6[48 "t\ m!
Ph\ Jꢂ6[7#e
a Spectra recorded in KBr plates[ b Spectra recorded in Nujol mull on a polyethylene _lm[ c Spectra recorded in CD1Cl1 at 182 K[ d Spectra recorded in CH1Cl1[ e Spectra recorded w CDCl2
at 182 K[
Table 1[ Selected IR and NMR data for tungsten "II# alkyne complexes 4Ð7
a
IR"n\ cm−0
#
0H NMRb
"d\ ppm^ J\ Hz#
02C"0H# NMRb
"d\ ppm^ J\ Hz#
Complex
n"CO#
n"CN#
ðWCl1"CO#"NCMe#"PhC2CPh#1Ł "4#
1977 "s# 1218 "w#
1187 "vw#
1[31 "s\ CH2CN#
199[62 "s\ 0 CO#\ 065[07 "s\ 1 PhC2CPh#\ 056[11 "s\ 1 PhC2CPh#\
039[33 "s\ 1 CiÐPh#\ 028[37 "s\ 1 CiÐPh#\ 015[85 "s\ 0 CH2CN#\ 4[06
"s\ 0 CH2CN#
ðWCl1"NCMe#1"PhC2CPh#1Ł "5#
ðWCl1"CO#"NCMe#"PhC2CH#1Ł "6#
ðWCl1"NCMe#1"PhC2CH#1Ł "7#
*
1216 "w#
1188 "vw#
1[28 "s\ 1 CH2CN#
084[85 "s\ 1 PhC2CPh#\ 078[15 "s\ 1 PhC2CPh#\ 027[52 "s\ 1 CiÐ
Ph#\ 026[74\ "s\ 1 CiÐPh#\ 016[52 "s\ 1 CH2CN#\ 4[45 "s\ 1 CH2CN#
085[13 "s\ 0 CO#\ 072[52 "s\ 1 PhC2CH#\ 065[62 "s\ 1 PhC2CH#\
026[93 "s\ 1 CiÐPh#\ 3[71 "s\ 0 CH2CN#
085[53 "s\ 1 PhC2CH#\ 077[49 "s\ 1 PhC2CH#\ 025[33 "s\ 1 CiÐPh#\
4[11 "s\ 1 CH2CN#
1978 "s# 1218 "w#
1181 "vw#
*
1[44 "s\ 0 CH2CN# 00[89\ "s\ 1 PhC2CH#
1215 "w#
1299 "vw#
1[31 "s\
1
CH2CN# 00[50\00[44 "s\
1
PhC2CH#
a Spectra recorded in KBr disc[ b Spectra recorded w CDCl2 at 182 K[

2311
T[ Szymanska!Buzar and T[ G<owiak
ꢀ
obtained
for
a
crystal
approximately mation of deep blue\ insoluble solid in methylene
9[09×9[09×9[04 mm using a KM3 k!axis computer! chloride\ most probably the chloro!bridged dimer[
controlled ð19Ł four!circle di}ractometer operating in
Another method which proved useful in obtaining
the v!1u scan mode[ All measurements were made the compound 0 was the oxidative!addition reaction
using graphite!monochromated Mo Ka radiation of ðW"CO#3"NCMe1Ł with SnCl3 in dichloromethane[
Ä
"lꢂ9[60958 A# at 182 "2# K[ The accurate cell dimen! Baker and Bury brie~y mentioned the formation of
sions and the crystal orientation matrix were deter! mixture of compounds containing 0 by reaction of
mined by a least!squares re_nement of the setting ðW"CO#2"NCMe#2Ł with SnCl3 in acetonitrile\ but
angles of 29 carefully centred re~ections in the range without synthetic and spectroscopic details for 0 ð09Ł[
19[5>³1u³26[2>[ A total of 1003 unique re~ections
The compounds 1Ð3 containing nitriles with a
were measured\ of which 0884 "026 variables# with longer carbon chain\ were prepared in the reaction of
Ir3s "I# in the range 4 to 69> were used to solve and 0 with an appropriate nitrile at room temperature[
re_ne the structure in the monoclinic space group The compounds 0Ð3 are very soluble in nitriles and in
P10:m[ A surprisingly high R value "R0ꢂ9[9680\ acetone\ less soluble in chlorinated solvents "CH1Cl1\
wR1ꢂ9[0870# was obtained after _rst re_nement[ A CHCl2# but insoluble in hydrocarbon solvents[ They
di}erence synthesis at this stage revealed two regions are air!sensitive in solution but in the solid state it
2
Ä
of signi_cant electron density "00[1\ 7[9\ e:A # located can be stored under nitrogen for a month without
Ä
at approximately 9[4 A from both sides of W"0#\ Sn"0# decomposition[
and Cl"0# atoms[ During re_nement the molecule was
found to be disordered between three adjacent pos!
itions with occupancy factor 9[65\ 9[01 and 9[01 for
Structure of 0
W"0#\ Sn"0#\ Cl"0#[ Further re_nement of this three
The molecule ðWCl"SnCl2#"CO#2"NCMe#1Ł"0#\ is
shown in Fig[ 0 together with the atomic numering
scheme Selected interatomic bond distances and
angles are presented in Table 2[
site model gave
a _nal R0 value of 9[9459
"wR1ꢂ9[0435#[ The largest peak in the _nal di}erence
2
Ä
map was 1[75 e:A [ Goodness!of!_t was 0[029[ The
structure was given a weighting scheme in the
form wꢀ0:ðs1"F91#¦"9[9167P#1¦9[9999PŁ\ where
Pꢀ"F19¦1F1c#:2[
The environment of the tungsten atom is an almost
ideal capped octahedron with the tin atom occupying
the unique capping position above an octahedral face
de_ned by the bridging chlorine and two crys!
tallographically equivalent carbonyl groups[ The
octahedral face that is capped by the SnCl2 group is
distorted to allow a close approach of the tin atom[
The angles subtended at the tungsten atom by the
three atoms determining the capped face are in the
range 096[6"7#Ð097[1"3#>^ compared with the opposite
face\ determined by C"1#\ N"0# and N"0#i\ where the
angles are in the range 79[9"6#Ð82[2"4#>[ Thus\ there
is a distortion of octahedral symmetry in order to
accommodate the tin atom[
The structure was solved by the heavy!atom method
with the SHELXS!75 program ð10Ł and re_ned by a
full!matrix least!squares method\ using the SHELXL!
82 program ð11Ł[ Neutral atomic scattering factors
were taken from the SHELXL!82 program ð11Ł[ The
positions of C!bonded H atoms were calculated
assuming typical stereochemistry and three atoms
Ä
were re_ned with _xed positions at 9[85 A from the C
atoms to which they were bonded[
The remaining dimensions\ positional parameters
and equivalent isotropic thermal parameters and
anisotropic thermal parameters are deposited in sup!
plementary material[
In addition one may notice that the molecule of 0
is remarkable in its symmetry[ The crystallographic
plane of symmetry extends through W\ Sn\ Cl"0# and
RESULTS AND DISCUSSION
In 0884 we reported ð12Ł that a photochemical reac!
tion of W"CO#5 with SnCl3 led to the formation of
an orange crystalline air!sensitive complex[ This was
structurally identi_ed by single!crystal X!ray crys!
tallography as the _rst example of a dinuclear hal!
ogenocarbonyl complex of tungsten"II# with a WÐSn
bond[ When this product is dissolved in toluene and
acetonitrile added\ an equimolecular mixture of
ðWCl"SnCl2#"CO#2"NCMe#1Ł"0# and ðWCl1"CO#2
"NCMe#1Ł is formed immediately ð13Ł[ Recrys!
tallization of the mixture from CH1Cl1:to!
luene:heptane produces quite stable orange crystals of
0 while considerable less stable ðWCl1"CO#2"NCMe#1Ł
decomposes with loss of carbon monoxide and for!
Fig[ 0[ Molecular geometry of ðWCl"SnCl2#"CO#2
"NCMe#1Ł"0#[

Spectroscopic properties\ structure and reactivity of ðWCl"SnCl2#"CO#2"NCMe#1Ł
2312
Ä
Table 2[ Selected bond lengths "A# and angles "># with e[s[d[s in parentheses for 0
W"0#ÐSn"0#
W"0#ÐCl"0#
W"0#ÐN"0#
W"0#ÐC"1#
1[609"0#
1[400"4#
1[07"0#
1[99"1#
W"0#ÐC"0#
Sn"0#ÐCl"0#
Sn"0#ÐCl"1#
Sn"0#ÐCl"2#
0[886"02#
1[739"4#
1[222"3#
1[233"4#
C"0#ÐW"0#ÐC"1#
C"1#ÐW"0#ÐN"0#
C"1#ÐW"0#ÐCl"0#
C"0#ÐW"0#ÐC"0#i
Cl"0#ÐW"0#ÐC"0#
Cl"0#ÐW"0#ÐN"0#
N"0#ÐW"0#ÐN"0#i
N"0#ÐW"0#ÐC"0#
N"0#iÐW"0#ÐC"0#
Sn"0#ÐW"0#ÐCl"0#
Sn"0#ÐW"0#ÐN"0#
65[5"5#
82[2"4#
060[0"5#
096[6"7#
097[1"3#
79[9"2#
79[9"6#
050[1"4#
73[7"4#
54[7"0#
016[4"2#
Sn"0#ÐW"0#ÐC"1#
Sn"0#ÐW"0#ÐC"0#
Cl"2#ÐSn"0#ÐCl"2#i
Cl"2#ÐSn"0#ÐCl"1#
Cl"0#ÐSn"0#ÐCl"2#
Cl"0#ÐSn"0#ÐCl"1#
Cl"0#ÐSn"0#ÐW"0#
W"0#ÐSn"0#ÐCl"1#
W"0#ÐSn"0#ÐCl"2#
W"0#ÐCl"0#ÐSn"0#
012[0"5#
69[7"3#
090[2"2#
86[8"0#
78[4"0#
057[3"1#
42[6"0#
003[5"1#
019[3"0#
59[4"0#
Symmetry elements represented by i] x\ 9[4!y\ z[
Cl"1#[ In such an arrangement two acetonitrile ligands chlorine forms a stronger bond with the tungsten while
are crystallographically equivalent and e}ectively cis the SnÐCl bond is weakened[ The angle of 59[4"0#>
with N"0#ÐWÐN"0#i angle 79[9"6#> and the WÐN dis! subtended at the chlorine by the tungsten!tin bond
Ä
tances identical "1[07"0# A#[ Two CO groups in the agrees with the value 48[8"1#> for bridging chlorine in
capped face are mutually cis with C"0#ÐWÐC"0#i angle ðWCl"MeSnCl1#"CO#2"C3H09S1#Ł ð3Ł\ 59[4"0#> in
Ä
096[6"7#> and the same WÐC distance 1[99"0# A[ The ðMoCl"SnCl2#"CO#2"C3H09S1#Ł"CH1Cl1#
ð5Ł
and
angles between carbonyl groups in the capped and 50[5"0#> in ðMoCl"MeSnCl1#"CO#2"C09H7N1#Ł ð2Ł[ The
uncapped face are smaller with 65[5"5#> for C"1#ÐWÐ form of the tungsten atom coordination in 0 is indeed
C"0# angle[
very similar to the monocapped octahedral geometries
The WÐNÐC angle is 067"0#> to evidence that the observed earlier in WÐSn or MoÐSn compounds ð2\ 3\
nitrile ligand is coordinated in an almost linear 5Ł[ A common feature of those structures is the pres!
Ä
manner[ The CÐN lengths of 0[02"1# A are not sig! ence of a tin atom in the unique capping position and
Ä
ni_cant but are shorter than CÐN distance of 0[044 A a chlorine atom bridging the WÐSn or MoÐSn bond[
observed in free CH2CN ð14Ł[ Comparison of bond The tin atom in 0 is _ve!coordinate with a geometry
length for 0 and tungsten"9# complex\ reveals that that is best described as trigonal bipyramidal with
Ä
the WÐN distance is shorter in 0\ being 1[07"0# A vs[ the two chlorine atoms occupying the axial sites[ The
Ä
1[10 A"av# in ðW"CO#2"NCMe#2Ł ð15Ł\ while the tung! WSnCl1 unit is nearly planar with the tin atom only
Ä
Ä
sten!carbonyls distances in 0 are about 9[96 A longer\ 9[594"2# A out of the WÐCl"0#ÐCl"1# plane[ The Cl"0#Ð
being 1[99 A "av# vs[ 0[82 A "av# in tungsten"9# SnÐCl"2# and Cl"0#ÐSnÐCl"2#i angles are identical
complex[ This correlates qualitatively with the "78[4"0#># as are the WÐSnÐCl"2# and WÐSnÐCl"2#i
expected lower electron density and p!donor ability angles "019[3"0#>#[ However\ the Cl"0#ÐSnÐCl"1# angle
Ä
Ä
of the tungsten in the higher oxidation state[
is 057[3"1#>\ and the Cl"0#ÐSnÐW angle is much smaller
The tungsten atom is seven!coordinate and tin atom than 89>\ at 42[6"0#>^ so the trigonal bipyramid is
is _ve!coordinate\ with one chlorine atom occupying signi_cantly distorted[
a bridging position between the two metal atoms[ The
Similar capped octahedral geometry with two crys!
Ä
tungsten!tin bond is short at 1[609"0# A compared to tallographically equivalent nitrile and carbonyl
Ä
the sum of the relevant covalent radii of 1[86 A ð16\ groups seen in
0
has been detected for
Me\ Et ð20Ł[ However\ those
17Ł[ The WÐSn distances of 1[648"2# ð3Ł\ 1[620"0# ð07Ł\ ðWI1"CO#2"NCR#1Ł\ R
1
Ä
1[600"0# ð18Ł and 1[626"0# ð18Ł A have been observed complexes contain a carbonyl ligand in the unique
previously[ In view of the established p!acceptor capping position and two mutually trans iodine
properties of the ðSnCl2Ł− group it seems probable ligands[
that the bond does possess some double!bond charac!
The molecular structure of the recently investigated
ter ð29Ł[ The tin to bridging chlorine distance is ðWCl"SnCl2#"CO#2"h3!NBD#Ł ð06Ł is best described as
Ä
1[739"4# A\ being considerably longer than the other a capped trigonal prism with the tin atom lying above
Ä
tin!chlorine distances\ which are average 1[23 A\ indi! a square face formed by the chlorine atom and three
cates that this bond is much weaker than a tin!chlorine carbonyl groups[ Unlike the situation in other WÐSn
single bond[ The tungsten to bridging chlorine dis! compounds in ðWCl"SnCl2#"CO#2"h3!NBD#Ł the chlor!
Ä
tance is 1[400"4# A and indicates that the bridging ine attached to the tungsten does not bridge the WÐ

2313
T[ Szymanska!Buzar and T[ G<owiak
ꢀ
Sn bond[ The WÐCl bond length is much shorter at CO groups and a single signal from each carbon of
Ä
Ä
1[343"1# A and WÐSn distance longer at 1[653"0# A the two nitriles "Table 0#[
than in other WÐSn or MoÐSn compounds ð2\ 3\ 5Ł[
The electronic spectrum of 0 is quite similar to those
of the starting tungsten "II# compound ð12Ł and shows
one strong band at 149 nm with a shoulder at 189 nm
which\ because of its high intensity and its position is
assigned to CT transition pꢁ"CO#9dp"W#[ There is
Spectroscopic studies of nitrile compounds 0Ð3
The carbonyl region of the infrared spectra of the also another band at 287 nm[ Because of its relatively
compounds 0Ð3 in KBr are almost identical in show! low intensity it is assigned to a ligand!_eld transition[
ing three carbonyl bands "Table 0#[ The infrared spec!
trum of compound 0 shows three carbonyl bands at
n"CO# 1929vs\ 0824s"sh# and 0892vs cm−0 and is simi! Reaction of 0 with alkynes
lar to that for the analogous molybdenum!tin complex
obtained _rst time by Baker and Bury\ "n"CO# 1915s\
When the reaction of 0 with two molecular equi!
0828s and 0801vs cm−0 ð09Ł# but qualitatively di}erent valents of PhC2CPh at room temperature in CH1Cl1
from that reported by Baker and Bury for the tungsten was monitored by IR\ the substitution of the CO
compound "n"CO# 1906\ 0867 and 0823 cm−0 ð09Ł#[ As ligands by an alkyne can be observed[ The n"CO#
noted by Baker and Bury their tungsten complex was bands for 0 decrease\ while this of the alkyne complex
extremely unstable to exposure to air and could not at 1090 "s# appears[ The 0H\ 02C NMR and IR spectral
be isolated in a pure state[ This is marked contrast to data for the reaction product indicate that it is a mix!
the quite good stability of the complex obtained by ture of two alkyne compounds "Table 1#[ One
us[ However\ IR spectra of 0 in a dichloromethane compound\ with acetonitrile trans to CO ligand\ two
solution shows more than three bands in the carbonyl cis PhC2CPh ligands and two cis anionic ligands "Cl−#
stretching region] 1939 "s#\ 1919 "s#\ 0869 "m# and in the coordination sphere\ can be formulated as
0829 "vs# cm−0[ The spectral di}erences correspond to ðWCl1"CO#"NCMe#"PhC2CPh#1Ł 4\ which probably
di}erent coordination geometries\ and in a dichlo! has a structure similar to that observed by Baker et al[
romethane solution distinct isomers of 0 may co!exist\ for ðWI1"CO#"MeCN#"MeC2CMe#1Ł ð22Ł[ The other
as was proposed previously by Kummer and Graham alkyne compound does not contain CO in coor!
ð0Ł[ In the n"C2N# region of the IR spectra for 0 two dination sphere and can be formulated as
bands are observed[ One is the n"C2N# band and the ðWCl1"NCMe#1"PhC2CPh#1Ł 5[ Both compounds
other a combination band resulting from the sym! dimerize in solution\ _rst with a loss of carbon mon!
metrical CH2 deformation and the CÐC stretch which oxide and second with a loss of acetonitrile molecule
borrows its intensity from the n"C2N# ð14Ł[ For the to give probably the chloride!bridged dimer ðW"m!
compound 0 those bands are at 1219 and 1181 cm−0
\
Cl#Cl"NCMe#"PhC2CPh#1Ł1[ The dimeric compound
these are at higher frequencies than the n"C2N# band is less soluble than monomeric and could not be char!
in the free acetonitrile observed at 1157 cm−0 ð14Ł[ The acterized by 02C NMR spectroscopy in solution[ A
intensity ratio of the n"C2N# band to that of the similar dimerization process was observed by Baker et
combination band was found to di}er greatly between al[ in their molybdenum"II# and tungsten"II# diiodide
cis and trans isomers ð14Ł[ Two sharp bands of com! alkyne complexes ð22\ 23Ł[ In 02C NMR spectra of
parable intensities in the n"C2N# region of 0 are con! the reaction products two sets of carbon signals of
sistent with cis acetonitrile ligands ð14Ł[ The n"C2N# coordinated PhC2CPh for 4 and 5 are observed[
frequencies of coordinated propionitrile and butyron! However\ after prolonged reaction time "13 h# n"CO#
itrile in 1 and 2 were observed as one band at band characteristic of alkyne complex 4 disappears
1181 cm−0[ The lower frequency region of the infrared and in the residue obtained after evaporation of sol!
spectrum is dominated by the principal absorptions vent only compound 5 was identi_ed by NMR[ 02C
at 233\ 214 cm−0\ which can be regarded as ns and nas NMR spectra of 4 and 5 revealed acetylenic carbon
"SnÐCl# vibration[ This is in good agreement with resonances in the range from 085Ð056 ppm\ as is typi!
increased frequencies of these bands upon coor! cal for three!electron!donor alkynes[ The white pre!
dination to metal or other ligand[ Tin!halide fre! cipitate which appeared as the side product during the
quencies of ðSnCl2Ł− ion were observed in\ for reaction of 0 with alkynes was identi_ed as SnCl1\
0
example\ Et3NðSnCl2Ł at 184 "A0# and 142 cm−0 "E# what suggests that the SnCl−2 ligand undergoes
ð21Ł[
hydrolysis to SnCl1 and Cl− in the presence of an
The similarity of the IR spectra in a solid state of alkyne[
the series of nitrile compounds obtained by us\ shows
In the reaction of 0 with two molecular equivalents
that the most probable solid state structure for those of phenylacetylene\ a mixture of alkyne complexes is
compounds is the same as that of 0 "Fig[ 0#[
formed[ The monomeric compound ðWCl1"CO#
0
The H and 02C NMR spectra of the nitrile com! "MeCN#"PhC2CH#1Ł 6\ with a solitary CO ligand
pounds 0Ð3 are very similar and are consistent with was identi_ed as the main product by IR and NMR
the solid!state structure of 0 "Fig[ 0#[ The spectrum spectroscopy[ The other alkyne complex does not con!
shows one carbonyl resonance from three equivalent tain CO and most probably can be formulated as

Spectroscopic properties\ structure and reactivity of ðWCl"SnCl2#"CO#2"NCMe#1Ł
2314
ðWCl1"NCMe#1"PhC2CH#1Ł 7 "Table 1#[ However\ give an alkylidene complex initiating the increase of
complexes 6 and 7 are not the only reaction products the polymer chain[
because several other proton signals of coordinated
PA in the region 00Ð03 ppm appeared in the reaction Acknowled`ements*Authors thank KBN "Grant No 2T98A
983 09# for _nancial support of this work[
of PA with 0[ Also several lower intensity carbon
signals of coordinated PA were observed in 02C NMR
spectra[
REFERENCES
Catalytic activity of 0[ The starting point of the
present investigation was to examine the scope of our
earlier _nding ð24\ 25\ 26Ł that the formation of tung!
sten"II# might be an important event in the creation by
Lewis acids "Group 03 tetrachlorides# of the catalytic
activity of tungsten"9# compounds[ To be precise\
polymerization of PA occurs at room temperature in
CH1Cl1 containing tungsten"II# compound 0[ Treat!
ment of the resultant deep!red solution with a large
amount of methanol produced\ quantitatively\ poly!
"phenylacetylene# "PPA# as a _ne dark!orange powder
with a number!average molecular weight "Mw# of
4×092\ determined by GPC[ The polymers produced
were soluble in CH1Cl1\ CHCl2 and toluene[ IR and
0H NMR spectroscopy was used to establish the ster!
eochemistry in PPA as mainly trans ð08Ł[
However\ the catalytic coupling of alkynes in the
presence of 0 yields at least two types of product\
namely polymers with conjugated polyenic structures
and cyclic oligomers\ especially the aromatic cyclo!
trimers 0\1\3! and 0\2\4!triphenylbenzene[ Minor
amounts of other oligomers arise\ mainly linear
diphenylbutadienes\ which contain\ for example\
hydrogen derived from the solvent and also a dimer
of PA detected by MS as 0H!indene!0!"phenyl!
methylene#[
The intermediates formed in mechanisms most fre!
quently suggested for the catalytic polymerization and
cyclotrimerization of alkynes are alkylidene com!
plexes ð27Ł and metallacyclic species ð28Ł[ The cata!
lytically active species are\ as yet\ rather poorly
characterized[ Our results provide direct information
only as regards to the _rst step and strongly suggest
that the loss of three labile two!electron!donor ligands
"CO or CH2CN#\ and coordination of two alkyne
molecules as three!electron!donor ligands\ is common
to all the reactions studied[ In the reactions of 0 with
alkynes that we investigated\ the tungsten complexes
that could be isolated contained a cis arrangement of
the two alkyne ligands[ We were unable to isolate any
intermediates beyond the _rst bis"alkyne# complexes
and their decomposition product] 0H!indene!0!"phe!
nylmethylene#[ The formation of dimers\ cyclotrimers
and linear conjugated polyenic polymers involves oxi!
dative coupling and formation of a series of met!
alacyclic species ð28Ł[ The metallacycle formed with
four molecules of alkyne can then rearrange to an
alkylidene ligand\ as was observed by Yeh et al[ð39Ł[
The mechanism of PA polymerization induced by
tungsten"II# complex is therefore seen to involve a
series of stepwise cis insertions of coordinated PA
into a CÐW bond giving a metallacycloheptatriene
complex[ A further PA cis insertion then occurs to
0[ Kummer\ R[ and Graham\ W[ A[ G[\ Inor`[
Chem[\ 0857\ 6\ 209[
1[ Edgar\ K[\ Jonson\ B[ F[ G[\ Lewis\ J[ and Wild\
S[ B[\ J[ Chem[ Soc[\ A\ 0857\ 00\ 1740[
2[ Elder\ M[ and Hall\ D[\ Inor`[ Chem[\ 0858\ 7\
0157[
3[ Elder\ M[ and Hall\ D[\ Inor`[ Chem[\ 0858\ 7\
0162[
4[ Einstein\ F[ W[ B[ and Field\ J[ S[\ J[ Chem[ Soc[
Dalton\ 0864\ 05:06\ 0517[
5[ Anderson\ R[ A[ and Einstein\ F[ W[ B[\ Acta
Cryst[\ 0865\ B21\ 855[
6[ Panizo\ M[ and Cano\ M[\ J[ Or`anomet[ Chem[\
0874\ 176\ 110[
7[ Bell\ A[ and Walton\ R[ A[\ J[ Or`anomet[ Chem[\
0874\ 189\ 230[
8[ Iglesias\ M[\ Lorente\ A[ L[\ Del Pino\ C[ and
Santos\ A[\ J[ Or`anomet[ Chem[\ 0872\ 145\ 62[
09[ Baker\ P[ K[ and Bury\ A[\ J[ Or`anomet[ Chem[\
0878\ 248\ 078[
00[ Baker\ P[ K[ and Bury\ A[\ Polyhedron\ 0878\ 7\
806[
01[ Baker\ P[ K[ and Quinlan\ A[ J[\ Inor`[ Chim[
Acta\ 0878\ 051\ 068[
02[ Miguel\ D[\ Perez!Martinez\ J[ A[\ Riera\ V[ and
ꢀ
Garcia!Granda\ S[\ Polyhedron\ 0880\ 09\ 0606[
03[ Miguel\ D[\ Perez!Martinez\ J[ A[\ Riera\ V[ and
ꢀ
Garcia!Granda\ S[\ J[ Or`anomet[ Chem[\ 0882\
344\ 010[
04[ Barrado\ G[\ Miguel\ D[\ Perez!Martinez\ J[ A[\
ꢀ
Riera\ V[ and Garcia!Granda\ S[\ J[ Or`anomet[
Chem[\ 0882\ 352\ 016[
05[ Cano\ M[\ Panizo\ M[\ Campo\ J[ A[\ Tornero\ J[
and Menendez\ N[\ J[ Or`anomet[ Chem[\ 0882\
ꢀ
352\ 010[
06[ Szymanska!Buzar\ T[\ G<owiak\ T[\ Polyhedron\
ꢀ
0886\ 05\ 0488[
07[ Dobson\ G[ R[\ Amr El Syed\ M[ F[\ Stolz\ I[ W[
and Sheline\ R[ K[\ Inor`[ Chem[\ 0850\ 0\ 415[
08[ Simionescu\ C[ J[\ Percec\ V[ and Dumitrescu\ S[\
J[ Polym[ Sci[ Polym[ Chem[\ 0866\ 04\ 1386[
19[ G[ R[\ KUMA KM3 Software\ User|s Guide\ Ver!
sion 2[0\ KUMA DIFFRACTION\ Wroc<aw\
Poland\ 0878[
10[ Sheldrick\ G[ M[\ Acta Crystallo`r[\ A[\ 0889\ 35\
356[
11[ Sheldrick\ G[ M[\ SHELXL82\ Program for the
Re_nement of Crystal Structure\ University of
GoÃttingen\ Germany[
12[ Szymanska!Buzar\ T[\ G<owiak\ T[\ J[ Or`an!
ꢀ
omet[ Chem[\ 0884\ 378\ 196[
13[ Szymanska!Buzar\ T[\ J[ Or`anomet[ Chem[\
ꢀ
0884\ 381\ 130[
14[ Storho}\ B[ N[ and Lewis\ Jr[\ H[ C[\ Coord[
Chem[ Rev[\ 0866\ 12\ 0[
15[ Hamilton\ E[ J[\ Smith\ D[ E[ and Welch\ A[ J[\
Acta Crystallo`r[\ C\ 0876\ 32\ 0103[

2315
T[ Szymanska!Buzar and T[ G<owiak
ꢀ
16[ Siemion\ V[ A[\ Chapovskii\ Y[ A[\ Struchkov\ 23[ Armstrong\ E[ M[\ Baker\ P[ K[ and Drew\ M[ G[
Yu[ T[ and Nesmeyanov\ A[ N[\ Chem[ Commun[\
0857\ 555[
B[\ Or`anometallics\ 0877\ 6\ 208[
24[ Szymanska!Buzar\ T[\ J[ Mol[ Catal[\ 0880\ 57\
ꢀ
17[ O|Connor\ J[ E[ and Corey\ E[ R[\ J[ Am[ Chem[
Soc[\ 0856\ 78\ 2829[
18[ Balch\ A[ L[ and Oram\ D[ E[\ Or`anometallics\
0877\ 6\ 044[
29[ Petz\ W[\ Chem[ Rev[\ 0875\ 75\ 0908[
20[ Drew\ M[ G[ B[\ Baker\ P[ K[\ Amstrong\ E[ M[\
Fraser\ S[ G[\ Muldoon\ D[ J[\ Lavery\ A[ J[ and
Shawcross\ A[\ Polyhedron\ 0884\ 03\ 506[
21[ Clark\ R[ J[ H[\ Maresca\ L[ and Smith\ P[ J[\ J[
Chem[ Soc[\ A[\ 0869\ 05\ 1576[
066[
25[ Szymanska!Buzar\ T[\ J[ Mol[ Catal[\ 0883\ 82\
ꢀ
026[
26[ Szymanska!Buzar\ T[\ J[ Mol[ Catal[\ A] Chemi!
ꢀ
cal\ 0886\ 012\ 002[
27[ Schrock\ R[ R[\ J[ Or`anomet[ Chem[\ 0875\ 299\
138 and references therein[
28[ Vollhardt\ K[ P[ C[\ An`ew[ Chem[ Int[ Ed[ En`l[\
0873\ 12\ 428[
39[ Yeh\ W[!Y[\ Pengband\ S[!M[ and Lee\ G[!H[\ J[
Chem[ Soc[ Chem[ Comm[\ 0882\ 02\ 0945[
22[ Armstrong\ E[ M[\ Baker\ P[ K[ and Drew\ M[ G[
B[\ J[ Or`anomet[ Chem[\ 0876\ 225\ 266[