Halocarbonyl alkyne complexes of molybdenum (II) : Crystal structures of [MoI2 (CO) (NCMe) (η2-RC2R) 2] (R=Me and Ph) and [MoI2 (CO) (5,6-Me2-1,10-phen) (η2-PhC2Ph) ]

Article abstract of DOI:10.1016/S0277-5387(98)00132-6

Reaction of [MoXX′ (CO) ₃ (NCMe) ₂] with RC₂R′ in CH₂Cl₂ at room temperature gave the bis (alkyne) complexes [MoXX′ (CO) (NCMe) (η²-RC₂R′) ₂] (X=X′=I, R=R′=Me; X=X′=Br, R=R′=Me, Ph; X′=I, X=Cl, Br, R=R′=Me, Ph) (1→7) in high yield. The molecular structures of [MoI₂ (CO) (NCMe) (η²-RC₂R) ₂] (R=Me, Ph) have been determined by X-ray crystallography. The two structures are very similar, with the two alkyne ligands cis- and parallel to each other and trans- to the two iodo ligands. The carbon monoxide and acetonitrile ligands occupy the two axial sites. Treatment of [MoI₂ (CO) (NCMe) (η²-RC₂Ph) ₂] with an equimolar amount of L^∩L {for R=Ph, L^∩L=5,6-Me₂-1,10-phen, Ph₂P (CH₂) ₂PPh₂; for R=Me, L^∩L=2,2′-bipy, Ph₂P (CH₂) _nPPh₂, n=1, 3, 4} yielded the mono (alkyne) complexes [MoI₂ (CO) (L^∩L) (η²-RC₂Ph) ] (8→13) , which for L^∩L=5,6-Me₂-1,10-phen, R=Ph (8) was crystallogaphically characterised. The geometry around the molybdenum centre is essentially octahedral, with the phenanthroline ligand trans- to a carbonyl and an iodide ligand, with the alkyne and other iodide group in the axial sites. Reaction of [MoI₂ (CO) (NCMe) (η²-MeC₂Ph) ₂] with two equivalents of NaS₂CNMe₂ in CH₂Cl₂ gave [Mo (CO) (S₂CNMe₂) ₂ (η²-MeC₂Ph) ] (14) .

Full text of DOI:10.1016/S0277-5387(98)00132-6

Polyhedron Vol[ 06\ No[ 08\ pp[ 2344Ð2355\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99021Ð5
Halocarbonyl alkyne complexes of
molybdenum"II#] crystal structures of
ðMoI1"CO#"NCMe#"h1!RC1R#1Ł "RꢀMe
and Ph# and ðMoI1"CO#"4\5!Me1!0\09!phen#
"h1!PhC1Ph#Ł
Nicholas G[ Aimeloglou\a Paul K[ Baker\a\ꢀ Margaret M[ Meehana and
Michael G[ B[ Drewb
a Department of Chemistry\ University of Wales\ Bangor\ Gwynedd\ LL46 1UW\ U[K[
b Department of Chemistry\ University of Reading\ Whiteknights\ Reading\ RG5 5AD\ U[K[
"Received 05 January 0887^ accepted 02 April 0887#
Abstract*Reaction of ðMoXX?"CO#2"NCMe#1Ł with RC1R? in CH1Cl1 at room temperature gave the bis
"alkyne# complexes ðMoXX?"CO#"NCMe#"h1!RC1R?#1Ł "XꢁX?ꢁI\ RꢁR?ꢁMe^ XꢁX?ꢁBr\ RꢁR?ꢁMe\
Ph^ X?ꢁI\ XꢁCl\ Br\ RꢁR?ꢁMe\ Ph# "0:6# in high yield[ The molecular structures of ðMoI1"CO#"NCMe#
"h1!RC1R#1Ł "RꢁMe\ Ph# have been determined by X!ray crystallography[ The two structures are very similar\
with the two alkyne ligands cis! and parallel to each other and trans! to the two iodo ligands[ The carbon
monoxide and acetonitrile ligands occupy the two axial sites[ Treatment of ðMoI1"CO#"NCMe#"h1!RC1Ph#1Ł
with an equimolar amount of L+L "for RꢁPh\ L+Lꢁ4\5!Me1!0\09!phen\ Ph1P"CH1#1PPh1^ for RꢁMe\
L+Lꢁ1\1?!bipy\ Ph1P"CH1#nPPh1\ nꢁ0\ 2\ 3# yielded the mono"alkyne# complexes ðMoI1"CO#"L+L#"h1!
RC1Ph#Ł "7:02#\ which for L+Lꢁ4\5!Me1!0\09!phen\ RꢁPh "7# was crystallogaphically characterised[ The
geometry around the molybdenum centre is essentially octahedral\ with the phenanthroline ligand trans! to
a carbonyl and an iodide ligand\ with the alkyne and other iodide group in the axial sites[ Reaction of
ðMoI1"CO#"NCMe#"h1!MeC1Ph#1Ł with two equivalents of NaS1CNMe1 in CH1Cl1 gave ðMo"CO#"S1CNMe1#1
"h1!MeC1Ph#Ł "03#[ Þ 0887 Elsevier Science Ltd[ All rights reserved
Keywords] halocarbonyl alkyne complex^ molybdenum"II#^ crystal structures[
———————————————————————————————————————————————
Alkyne ligands have orthogonal pp!orbitals which valents of RC1R? to yield ðMI1"CO#"NCMe#"h1!
enables them to have variable electron!donor inter! RC1R?#1Ł "MꢁMo\ W\ RꢁR?ꢁPh\ RꢁMe\ R?ꢁPh^
actions to a transition!metal centre[ This can range MꢁW\ RꢁR?ꢁMe\ CH1Cl\ p!tol\ RꢁPh\
from two to four electrons depending upon which R?ꢁCH1OH# and the dimeric molybdenum complex
ð"Mo"m!I#I"CO#"h1!MeC1Me#1#1Ł[ The molecular
complex is being considered ð0Ł[ Both experimental
studies ð1\2Ł and theoretical calculations ð3Ð6Ł support
structures of ðWI1"CO#"NCMe#"h1!RC1R#1Ł "RꢁMe
and Ph# were crystallographically determined ð09Ł[ At
the time we considered the molybdenum complexes
were much less stable than their tungsten analogues^
in particular it was found di.cult to isolate ð09Ł the
bis"but!1!yne# complex ðMoI1"CO#"NCMe#"h1!MeC1
Me#1Ł\ which dimerised to give ð"Mo"m!I#I"CO#
"h1!MeC1Me#1#1Ł[ One example of the di}erent reac!
tivity pattern of the two metals has also been pre!
viously observed ð00Ł\ namely the reaction of
ðMI1"CO#"NCMe#"h1!PhC1Ph#1Ł with one equivalent
this variable electron donor ability of alkynes[ A wide
range of alkyne complexes of molybdenum"II# and
tungsten"II# have been reported ð7\8Ł\ and the
majority of these have alkyne ligands which donate
four electrons to the metal[
In 0877 ð09Ł\ we described the reactions of
ðMI1"CO#2"NCMe#1Ł "MꢁMo or W# with two equi!
ꢀ Author to whom correspondence should be addressed[
2344

2345
N[ G[ Aimeloglou et al[
of PPh2 which gave ðMoI1"CO#"PPh2#"h1!PhC1Ph#1Ł ðMoI1"CO#"4\5!Me1!0\09!phen#"h1!PhC1Ph#Ł 7
or
ðWI1"CO#"NCMe#"h1!PhC1Ph#1Ł\
"h1!PhC1Ph#1Ł and ðWI1"CO#"PPh2#1"h1!PhC1Ph#Ł[
a
mixture of products for MꢁW\ namely
ðWI1"CO#"PPh2#
To a solution of ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł
"9[1 g\ 9[147 mmol# dissolved in CH1Cl1 "19 cm2# with
We have reinvestigated the reactions of continuous stirring at room temperature was added\
ðMoXX?"CO#2"NCMe#1Ł with alkynes to give 4\5!Me1!0\09!phen "9[943 g\ 9[147 mmol# and the reac!
ðMoXX?"CO#"NCMe#"h1!RC1R?#1Ł\ and in this paper tion mixture stirred for 13 hrs[ The product was then
describe their reactivity with both neutral and anionic washed with hexane "19 cm2# and diethyl ether
donor ligands[ The molecular structures of the com! "29 cm2# to give the dark orange complex ðMoI1
plexes ðMoI1"CO#"NCMe#"h1!RC1R#1Ł "RꢁMe and "CO#"4\5!Me1!phen#"h1!PhC1Ph#Ł "7# "yieldꢁ9[06 g\
Ph# and ðMoI1"CO#"4\5!Me1!0\09!phen#"h1!PhC1Ph#Ł 82)#[ Suitable crystals as their CDCl2 solvate for X!
are also described[
ray analysis were grown from CDCl2 at 187 K in an
NMR tube over 6 days[
In a similar reaction of ðMoI1"CO#"NCMe#"h1!
PhC1Ph#1Ł with an equimolar amount of Ph1P"CH1#1
PPh1 gave ðMoI1"CO#"Ph1P"CH1#1PPh1#"h1!PhC1Ph#Ł
"8#[
EXPERIMENTAL
All reactions described in this paper were carried
out under a dry dinitrogen atmosphere using vac!
uum:Schlenk line techniques[ The starting materials\
ðMoXX?"CO#2"NCMe#1Ł "XꢁX?ꢁI ð01Ł\ Br ð02Ł^
XꢁCl\ X?ꢁI ð03Ł^ XꢁBr\ X?ꢁI ð04Ł# and
ðMoI1"CO#"NCMe#"h1!RC1Ph#1Ł "RꢁMe\ Ph# ð09Ł
were prepared by the published methods[ The solvents
diethyl ether and dichloromethane were dried and dis!
tilled before use[ All chemicals used in this research
were purchased from commercial sources[
Elemental analyses "C\ H and N# were determined
using a Carlo Erba Elemental Analyser MOD 0097
"using helium as a carrier gas#[ Infrared spectra were
recorded as thin CHCl2 _lms between NaCl plates on
a Perkin!Elmer 0599 series FTIR spectrophotometer[
0H and 02C "referenced to SiMe3# and 20P "referenced
to 74) H2PO3# NMR spectra were recorded on a
Bruker AC 149 NMR spectrometer[
ðMoI1"CO#"Ph1P"CH1#PPh1#"h1!MeC1Ph#Ł 00
To a solution of ðMoI1"CO#"NCMe#"h1!MeC1Ph#1Ł
"9[2 g\ 9[350 mmol#\ dissolved in degassed CH1Cl1
"19 cm2#\ with continuous stirring under a stream of
dry dinitrogen\ was added Ph1P"CH1#PPh1 "9[066 g\
9[350 mmol#\ and the mixture stirred for 13 hrs[ Fil!
tration over Celite and removal of the solvent in vacuo
gave the dark red crystalline complex ðMoI1"CO#
"Ph1P"CH1#PPh1#"h1!MeC1Ph#Ł "00# "Yieldꢁ9[26 g\
80)#\ which was then washed with hexane "29 cm2#
and diethylether "19 cm2#[
In a similar fashion\ reactions of ðMoI1"CO#
"NCMe#"h1!MeC1Ph#1Ł with an equimolar amount
1\1?!bipy or Ph1P"CH1#nPPh1 "nꢁ2\ 3# in CH1Cl1 gave
the complexes ðMoI1"CO#"1\1?!bipy#"h1!MeC1Ph#Ł
"09# and ðMoI1"CO#"Ph1P"CH1#nPPh1#"h1!MeC1Ph#Ł
"01# "nꢁ2# and "02# "nꢁ3#[
Preparations
ðMoI1"CO#"NCMe#"h1!MeC1Me#1Ł[0CH1Cl1 0
ðMo"CO#"S1CNMe1#1"h1!MeC1Ph#Ł 03
1
To a solution of ðMoI1"CO#2"NCMe#1Ł "0[9 g\
0[8 mmol# dissolved in CH1Cl1 "29 cm2# in a foil
covered Schlenk tube at room temperature was added
but!1!yne "9[5 g\ 6[7 mmol# and the reaction was stirred
for 0 hr[ The resulting red solution was _ltered\ and
the solvent removed in vacuo giving a red crystalline
To a solution of ðMoI1"CO#"NCMe#"h1!MeC1Ph#1Ł
"9[1 g\ 9[20 mmol# dissolved in CH1Cl1 "19 cm2# at
room temperature was added NaðS1CNMe1Ł "9[97 g\
9[50 mmol# and the reaction mixture stirred for 13 hrs[
The resulting solution was _ltered\ and the solvent
removed in vacuo giving a purple powder\ which was
washed with hexane "29 cm2# and diethyl ether
"19 cm2# to give ðMo"CO#"S1CNMe1#1"h1!MeC1Ph#Ł
"03#[ Yieldꢁ9[09 g\ 72)[
solid of ðMoI1"CO#"NCMe#"h1!MeC1Me#1Ł[0CH1Cl1
1
0[ This was recrystallised by cooling a CH1Cl1 solution
of the complex to −06>C to yield single crystals
0
suitable for X!ray crystallography of 0 as a MeOH
solvate\ which must have arisen as a result of1a small
amount of MeOH remaining in the degassing unit X!ray crystallo`raphy
before degassing the CH1Cl1 used in this reaction[
Yield 9[8 g\ 89)[
Crystals of complexes\ 0\ ðMoI1"CO#"NCMe#"h1!
Similar reactions of ðMoXX?"CO#2"NCMe#1Ł PhC1Ph#1Ł\ and 7 were grown as described in the exper!
"XꢁX?ꢁBr\ I\ XꢁBr\ Cl\ X?ꢁI# with two equi! imental section[ Crystal data for the three structures
valents of diphenylacetylene or 3 equivalents of but! are given in Table 0\ together with re_nement details[
1!yne in CH1Cl1 gave the products ðMoXX?"CO# Bond lengths and angles for the metal coordination
"NCMe#"h1!RC1R#1Ł "XꢁX?ꢁBr\ I^ XꢁBr\ Cl\ spheres of 0\ ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł and 7
X?ꢁI^ RꢁMe\ Ph# 1:6[
are given in Table 1[ Data were collected with MoKa

Halocarbonyl alkyne complexes of molybdenum"II#
2346
Table 0[ Crystal data and structure re_nement for 0\ ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł and 7[
ðMoI1"CO#"NCMe#
"0#
"h1!PhC1Ph#1Ł
"7#
Empirical formula
C00[4 H06 I1 Mo N O0[4
C20[14 H12[4 Cl9[4 I1
Mo N O
685[36
182 "1#
9[60962
C18[4 H13[4 Cl0[4
I1 Mo N1
714[82
182 "1#
9[60962
Formula weight
Temperature "K#
448[91
182 "1#
9[60962
Ä
Wavelength "A#
Crystal system
Space group
Unit cell dimensions a"A#
triclinic
P!0
monoclinic
C1:c
23[40"2#
09[562"09#
08[58"1#
"89#
004[18"0#
"89#
5447"00#
7
0[501
1[234
monoclinic
P10:n
03[963"01#
05[385"03#
03[751"01#
"89#
095[12"0#
"89#
2204"4#
Ä
6[551"8#
7[913 "8#
04[504"03#
68[90"0#
66[41"0#
77[80"0#
819"1#
Ä
b"A#
Ä
c"A#
a"deg#
b"deg#
t"deg#
2
Ä
Volume "A #
Z
1
3
Density "calculated# "Mg:m2#
Absorption coe.cient "mm−0
F"999#
0[859
3[959
413
0[545
1[392
0477
#
2945
Crystal size "mm#
u range for data collection "deg#
Index ranges
9[04×9[19×9[19
1[61 to 13[87
9³ꢁh³ꢁ8\
−7³ꢁk³ꢁ8\
−06³ꢁ0³ꢁ07
1328
9[14×9[14×9[24
1[91 to 14[29
9³ꢁh³ꢁ30
−00³ꢁk³ꢁ00
−12³ꢁ0³ꢁ10
6121
3242 "9[9678#
3242:9:228
9[140\ 9[999
0[991
9[2×9[14×9[14
1[36 to 14[04
9³ꢁh³ꢁ05
−08³ꢁk³ꢁ08
−06³ꢁ0³ꢁ05
5547
3608 "9[9673#
3608:9:244
9[198\ 9[999
9[867
Re~ections collected
Independent re~ections "Rint#
Data:restraints:parameters
Weighting Scheme "a\b#ꢀ
Goodness!of!_t on F1
Final R indices ðI×1s"I#Ł R0
wR1
1328
1328:9:060
9[982\ 4[031
0[942
9[9375\
9[0274
9[0928
9[1801
9[9783
9[1224
R indices "all data# R0
wR1
9[9427\
9[0342
9[0464
9[2468
9[0331
9[1666
Largest di}[ peak and hole e[AÐ!2
0[903\ −0[913
0[450\ −9[735
1[269\ −0[258
ꢀ Weighting scheme wꢁ0:"s1"Fo1#¦"aP#1¦bP#\ where Pꢁ"Fo1¦1F1c #:2
radiation using the MAR Research Image Plate Silicon Graphics R3999 Workstation at the University
System[ The crystals were positioned at 64 mm from of Reading[
the Image Plate[ 84 frames were measured at 1> inter!
vals with a counting time of 1 mins[ Data analysis was
carried out with the XDS program ð05Ł[ All three
structures were solved using direct methods with the
RESULTS AND DISCUSSION
Shelx75 program ð06Ł[ The non!hydrogen atoms were ðMXX?"CO#"NCMe#"h1!RC1R?#1Ł complexes
re_ned with anisotropic thermal parameters[ The
hydrogen atoms were included in geometric positions
The starting materials for this research\ namely
and given thermal parameters equivalent to 0[1 times ðMoXX?"CO#2"NCMe#1Ł "XꢁX?ꢁI ð01Ł\ Br ð02Ł^
those of the atom to which they were attached[ In all XꢁCl\ X?ꢁI ð03Ł^ XꢁBr\ X?ꢁI ð04Ł# were prepared
three structures\ disordered solvent molecules were as described previously ð01Ð04Ł by reacting the zero!
located[ In "0#\ a solvent methanol was given 49) valent complex fac!ðMo"CO#2"NCMe#2Ł "prepared in
occupancy\ in ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł a situ# with an equimolar amount of XX?[ Reaction
solvent dichloromethane was given 14) occupancy of ðMoXX?"CO#2"NCMe#1Ł with two equivalents of
and in "7# a solvent trichloromethane was given 49) RC1R? in CH1Cl1 at room temperature gives the bis"al!
occupancy[ Empirical absorption corrections were kyne# complexes ðMoXX?"CO#"NCMe#"h1!RC1R?#1Ł
applied ð07Ł[ The structures were then re_ned using "XꢁX?ꢁI\ RꢁR?ꢁMe^ XꢁX?ꢁBr\ RꢁR?ꢁMe\
Shelxl ð08Ł[ All calculations were carried out on a Ph^ XꢁBr\ X?ꢁI\ RꢁR?ꢁMe\ Ph^ XꢁCl\ X?ꢁI\

2347
N[ G[ Aimeloglou et al[
Table 1[ Bond lengths ðAŁ and angles ðdegŁ for the metal coordination
spheres of 0\ ðMoI1"CO#"NCMe#"h!PhC1Ph#1Ł and 7[
in "0#
Mo"0#ÐC"00#
Mo"0#ÐC"40#
Mo"0#ÐC"10#
Mo"0#ÐC"30#
Mo"0#ÐC"20#
Mo"0#ÐN"01#
Mo"0#ÐI"1#
Mo"0#ÐI"0#
1[917"09#
1[987"8#
1[093"8#
1[033"09#
1[043"7#
1[195"7#
1[894"1#
1[813"1#
C"00#ÐMo"0#ÐC"40#
C"00#ÐMo"0#ÐC"10#
C"40#ÐMo"0#ÐC"10#
C"00#ÐMo"0#ÐC"30#
C"40#ÐMo"0#ÐC"30#
C"10#ÐMo"0#ÐC"30#
C"00#ÐMo"0#ÐC"20#
C"40#ÐMo"0#ÐC"20#
C"10#ÐMo"0#ÐC"20#
C"30#ÐMo"0#ÐC"20#
C"00#ÐMo"0#ÐN"01#
C"40#ÐMo"0#ÐN"01#
C"10#ÐMo"0#ÐN"01#
C"30#ÐMo"0#ÐN"01#
C"20#ÐMo"0#ÐN"01#
C"00#ÐMo"0#ÐI"1#
C"40#ÐMo"0#ÐI"1#
C"10#ÐMo"0#ÐI"1#
C"30#ÐMo"0#ÐI"1#
C"20#ÐMo"0#ÐI"1#
N"01#ÐMo"0#ÐI"1#
C"00#ÐMo"0#ÐI"0#
C"40#ÐMo"0#ÐI"0#
C"10#ÐMo"0#ÐI"0#
C"30#ÐMo"0#ÐI"0#
C"20#ÐMo"0#ÐI"0#
N"01#ÐMo"0#ÐI"0#
I"0#ÐMo"0#ÐI"1#
098[7"3#
098[5"3#
85[2"3#
63[7"3#
24[0"3#
094[3"3#
63[7"3#
094[3"3#
23[8"3#
82[4"3#
052[7"3#
79[7"2#
79[4"2#
004[5"2#
004[0"2#
72[6"2#
052[0"2#
77[3"2#
046[2"2#
76[7"1#
73[9"1#
72[3"2#
76[7"2#
052[8"1#
75[8"2#
046[2"2#
73[7"1#
72[36"7#
In ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł
Mo"0#ÐC"00#
Mo"0#ÐC"40#
Mo"0#ÐC"10#
Mo"0#ÐC"20#
Mo"0#ÐN"01#
Mo"0#ÐC"30#
Mo"0#ÐI"1#
Mo"0#ÐI"0#
C"00#ÐMo"0#ÐC"40#
C"00#ÐMo"0#ÐC"20#
C"40#ÐMo"0#ÐC"20#
C"00#ÐMo"0#ÐC"10#
C"40#ÐMo"0#ÐC"10#
C"20#ÐMo"0#ÐC"10#
C"00#ÐMo"0#ÐN"01#
C"40#ÐMo"0#ÐN"01#
C"20#ÐMo"0#ÐN"01#
C"10#ÐMo"0#ÐN"01#
C"00#ÐMo"0#ÐC"30#
C"40#ÐMo"0#ÐC"30#
C"20#ÐMo"0#ÐC"30#
1[97"1#
1[98"1#
1[09"1#
1[00"1#
1[06"1#
1[08"1#
1[803"2#
1[835"2#
000[0"5#
004[9"6#
85[4"6#
79[0"6#
093[0"5#
24[4"5#
048[9"6#
68[3"5#
79[3"5#
004[8"5#
64[5"6#
25[0"5#
095[2"5#
"continued on next pa`e#

Halocarbonyl alkyne complexes of molybdenum"II#
Table 1 "continued#
2348
C"10#ÐMo"0#ÐC"30#
N"01#ÐMo"0#ÐI"1#
C"00#ÐMo"0#ÐI"1#
C"40#ÐMo"0#ÐI"1#
C"20#ÐMo"0#ÐI"1#
C"10#ÐMo"0#ÐI"1#
N"01#ÐMo"0#ÐI"1#
C"30#ÐMo"0#ÐI"1#
C"00#ÐMo"0#ÐI"0#
C"40#ÐMo"0#ÐI"0#
C"20#ÐMo"0#ÐI"0#
C"10#ÐMo"0#ÐI"0#
N"01#ÐMo"0#ÐI"0#
C"30#ÐMo"0#ÐI"0#
I"1#ÐMo"0#ÐI"0#
81[9"5#
004[1"5#
70[7"4#
051[9"3#
77[5"3#
89[9"3#
73[4"3#
045[6"3#
65[1"5#
75[8"4#
054[6"4#
045[0"4#
75[5"3#
73[6"3#
73[05"7#
in "7#
Mo"0#ÐC"40#
Mo"0#ÐC"30#
Mo"0#ÐC"00#
1[922"02#
1[931"00#
1[99"1#
Mo"0#ÐN"11#
Mo"0#ÐN"00#
Mo"0#ÐI"1#
Mo"0#ÐI"0#
1[191"09#
1[159"09#
1[723"1#
1[757"1#
26[2"4#
C"40#ÐMo"0#ÐC"30#
C"40#ÐMo"0#ÐC"00#
C"30#ÐMo"0#ÐC"00#
C"40#ÐMo"0#ÐN"11#
C"30#ÐMo"0#ÐN"11#
C"00#ÐMo"0#ÐN"11#
C"40#ÐMo"0#ÐN"00#
C"30#ÐMo"0#ÐN"00#
C"00#ÐMo"0#ÐN"00#
N"11#ÐMo"0#ÐN"00#
C"40#ÐMo"0#ÐI"1#
C"30#ÐMo"0#ÐI"1#
C"00#ÐMo"0#ÐI"1#
N"11#ÐMo"0#ÐI"1#
N"00#ÐMo"0#ÐI"1#
C"40#ÐMo"0#ÐI"0#
C"30#ÐMo"0#ÐI"0#
C"00#ÐMo"0#ÐI"0#
N"11#ÐMo"0#ÐI"0#
N"00#ÐMo"0#ÐI"0#
I"1#ÐMo"0#ÐI"0#
000[8"4#
63[5"4#
77[9"3#
80[4"3#
84[4"3#
72[7"3#
019[2"3#
050[9"4#
62[5"3#
85[1"2#
87[5"3#
82[2"3#
057[0"1#
84[6"2#
051[6"2#
046[9"3#
72[7"3#
71[8"2#
68[4"1#
89[0"0#
RꢁMe\ Ph# "0:6# in good yield[ Complexes 0:6 solvents such as CH1Cl1\ CHCl2\ but very much less
have been characterised by elemental analysis "C\ H soluble in diethyl ether and hydrocarbon solvents[
and N# "Table 2#\ IR "Table 3# and 0H NMR spectro!
The IR spectra for complexes 0:6\ all show single
scopy "Table 4#[ Repeated elemental analysis results carbonyl bands which are as expected at lower wave!
and 0H NMR spectroscopy con_rmed complexes 0\ 1\ number for the but!1!yne complexes compared to the
5 and 6 contained various amounts of CH1Cl1 as diphenylacetylene analogues[ All the complexes 0:6
a solvate in the crystal lattice[ Complexes 0:6\ have alkyne stretching bands at considerably lower
although less stable than related tungsten complexes wavenumber compared to the uncoordinated alkyne[
ð09\ 19\ 10Ł\ can be stored in the solid state under
dinitrogen for several days in the absence of light[ was prepared as previously described ð09Ł[ Single crys!
Complexes 0:6 are soluble in polar chlorinated tals suitable for X!ray analysis of
The complex ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł

2359
N[ G[ Aimeloglou et al[
Table 2[ Physical and Analytical Dataa for the halocarbonyl alkyne complexes of molybdenum"II#
Analysis ")#
Yield
Complex
Colour
")#
C
H
N
0
1
2
3
4
5
6
7
8
ðMoI1"CO#"NCMe#"h1!MeC1Me#1Ł[0CH1Cl1
ðMoBr1"CO#"NCMe#"h1!MeC1Me#11Ł[1CH1Cl1
ðMoBr1"CO#"NCMe#"h1!PhC1Ph#1Ł
Red
Orange
Orange
89
57
66
70
70
78
89
82
86
55
80
79
56
72
12[7 "13[0#
15[0 "15[9#
43[2 "43[5#
15[4 "16[4#
49[4 "40[9#
16[0 "15[4#
38[7 "38[1#
34[3 "34[4#
41[1 "40[5#
24[9 "23[4#
36[8 "36[8#
38[2 "38[9#
49[9 "38[5#
35[8 "35[1#
1[8 "1[7#
2[1 "2[1#
2[3 "2[3#
2[1 "2[0#
2[3 "2[1#
1[1 "2[9#
2[4 "2[0#
2[5 "1[8#
2[0 "2[4#
1[3 "1[2#
2[6 "2[3#
3[1 "2[7#
3[7 "3[9#
4[2 "3[8#
1[6 "1[5#
2[3 "1[5#
1[0 "1[9#
1[3 "1[8#
0[5 "0[8#
2[9 "1[6#
1[9 "0[7#
2[2 "2[6#
Ð
ðMoBrI"CO#"NCMe#"h1!MeC1Me#1Ł
Dark red
Dark red
Orange:Red
Red:Brown
Dark Orange
Orange
Dark Green
Dark red
Brown
ðMoBrI"CO#"NCMe#"h1!PhC1Ph#1Ł
ðMoClI"CO#"NCMe#"h1!MeC1Me#1Ł[CH1Cl1
ðMoClI"CO#"NCMe#"h1!PhC1Ph#1Ł[CH1Cl1
ðMoI1"CO#"4\5!Me1!0\09!phen#"h1!PhC1Ph#Ł
ðMoI1"CO#"Ph1P"CH1#1PPh1#"h1!PhC1Ph#Ł
09 ðMoI1"CO#"1\1?!bipy#"h1!MeC1Ph#Ł
3[9 "3[4#
Ð
00 ðMoI1"CO#"Ph1P"CH1#PPh1#"h1!MeC1Ph#Ł
01 ðMoI1"CO#"Ph1P"CH1#2PPh1#"h1!MeC1Ph#Ł
02 ðMoI1"CO#"Ph1P"CH1#3PPh1#"h1!MeC1Ph#Ł
03 ðMo"CO#"S1CNMe1#1"h1!MeC1Ph#Ł
Ð
Ð
Purple
Dark purple
5[4 "5[6#
a Calculated values in parenthesis[
Table 3[ Infrared spectrala data for the halocarbonyl alkyne complexes of
molybdenum"II#
Complex
n"N0C#:cm−0
n"C0O#:cm−0
n"C0C#:cm−0
0
1
2
3
4
5
6
7
1296"w#\ 1180"w#
1170"w#\ 1143"w#
1219"w#\ 1183"w#
1208"w#\ 1180"w#
1219"w#\ 1171"w#
1108"w#\ 1188"w#
1212"w#\ 1182"w#
Ð
Ð
Ð
Ð
Ð
Ð
Ð
1950"s#
1956"s#
1984"s#
1951"s#
1989"s#
1951"s#
1976"s#
0847"s#
0866"s#
0836"s#
0842"s#
0840"s#
0837"s#
0852"m#
0501"w#
0591"w#
0593"w#
0487"w#
0506"w#
0597"w#
0590"w#
0488"w#
0590"w#
0599"w#
0477"w#
0478"w#
0489"w#
0845"w#
8
09
00
01
02
03
a Spectra were recorded in CHCl2 as thin _lms between NaCl plates[
sꢁstrong\ mꢁmedium\ wꢁweak[
ðMoI1"CO#"NCMe#"h1!RC1R#1Ł "RꢁMe\ Ph# were sample of complex 0[ The structures of 0 and
grown by cooling a CH1Cl1 solution of the complexes ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł are shown in Figs
to −06>C for 13 hrs[ The single crystal chosen for X! 0 and 1 together with the atomic numbering schemes[
ray analysis of complex 0 contained a 01MeOH solvate The geometry of the coordination spheres for both
in the crystal lattice which probably arose from small complexes are listed in Table 1[ Both structures are
quantities of MeOH in the degassing unit containing isomorphous with their tungsten analogues ð09Ł and
CH1Cl1[ This is surprising\ but complex 0 has been contain equivalent coordination spheres with the
prepared a number of times and from elemental analy! molybdenum atoms bonded to two iodide atoms\ one
0
sis results and H NMR spectroscopy is always con! carbonyl group\ one acetonitrile group and two alkyne
_rmed as a 0CH1Cl1 solvate[ It must be that the ligands[ The geometry of the coordination spheres can
1
suitable single crystal of 0 chosen for X!ray analysis best be considered as six!coordinate with the alkyne
0
as a MeOH solvate is not representative of the bulk ligands each occupying one coordination site[ The two
1

Halocarbonyl alkyne complexes of molybdenum"II#
2350
Table 4[ Proton NMR data "d#ꢀ for the halocarbonyl alkyne complexes of molybdenum"II#
Complex
d "ppm#
0
1
2
3
4
5
6
7
4[2 "s\ 0 H\ CH1Cl1#^ 1[8 "s\ 5 H\ C1Me#^ 1[7 "s\ 5 H\ MeC1#^ 1[2 "s\ 2 H\ NCMe#
4[2 "s\ 3 H\ CH1Cl1#^ 2[9 "s\ 5 H\ C1Me#^ 1[7 "s\ 5 H\ MeC1#^ 1[1 "s\ 2 H\ NCMe#
6[8:6[4 "m\ 19 H\ Ph#^ 1[1 "s\ 2 H\ NCMe#
1[8 "s\ 5 H\ MeC1#^ 1[6 "s\ 5 H\ MeC1#^ 1[2 "s\ 2 H\ NCMe#
6[7:6[3 "m\ 19 H\ Ph#^ 1[2 "s\ 2 H\ NCMe#
4[2 "s\ 1 H\ CH1Cl1#^ 2[9 "s\ 5 H\ C1Me#^ 1[8 "s\ 5 H\ C1Me#^ 1[1 "s\ 2 H\ NCMe#
6[7:6[5 "m\ 19 H\ Ph#^ 4[2 "s\ 1 H\ CH1Cl1#^ 1[1 "s\ 2 H\ NCMe#
8[6:8[5 "br m\ 1 H\ phen#^ 7[8:7[5 "br m\ 1 H\ phen#^ 7[9:6[5 "br m\ 1 H\ phen#^ 6[5Ð6[2 "br m\ 09 H\ Ph#^
1[8:1[6 "br m\ 5 H\ Me#
8
09
7[9:5[4 "br m\ 29 H\ Ph#^ 2[3:2[1 "br m\ 1 H\ PCH1#^ 1[8:1[6 "br m\ 1 H\ PCH1#
7[4:7[3 "d\ 1 H\ bipy#^ 7[2:7[9 "br m\ 1 H\ bipy#^ 6[7:6[6 "br m\ 1 H\ bipy#^ 6[4:6[3 "br m\ 1 H\ bipy#^
6[2:6[1 "br s\ 4 H\ C1Ph#^ 1[7 "s\ 2 H\ C1Me#
00
01
02
03
7[9:5[8 "br m\ 14 H\ Ph#^ 3[7:3[6 "br m\ 1 H\ PCH1#^ 1[5 "s\ 2 H\ C1Me#
6[4:5[5 "br m\ 14 H\ Ph#^ 1[8:1[6 "br m\ 3 H\ PCH1#^ 1[5 "s\ 2 H\ C1Me#^ 1[4:1[2 "br m\ 1 H\ PCH1CH1#
6[8:5[5 "br m\ 14 H\ Ph#^ 1[8:1[6 "br m\ 3 H\ PCH1#^ 1[5 "s\ 2 H\ C1Me#^ 1[4:1[2 "br m\ 3 H\ PCH1CH1#
6[4:6[9 "br m\ 4 H\ Ph#^ 2[0 "s\ 01 H\ S1CNMe1#^ 1[6 "s\ 2 H\ C1Me#
ꢀ Spectra recorded in CDCl2 "¦14>C# and referenced to SiMe3] sꢁsinglet\ brꢁbroad\ dꢁdoublet\ mꢁmultiplet[
Fig[ 0[ Crystal structure of ðMoI1"CO#"NCMe#"h1!MeC1Me#1Ł "0# showing the atom numbering scheme[ Ellipsoids shown
at 29) probability[
Ä
iodine atoms are mutually cis and each is trans to "1# in "0# and 1[803 "2#\ 1[835 "2# A in
an alkyne group[ The carbonyl group is trans to the ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł compared to WÐI
Ä
acetonitrile group[
distances of 1[732Ð1[751 A in the tungsten analogues[
There is some small di}erence in geometry between Similar di}erences are found in the MoÐN distances
these two molybdenum complexes and their tungsten and to a lesser extent in the MoÐC distances[
analogues re~ecting the larger size of the molybdenum
The 0H NMR spectra of complexes 0:6 conforms
atom[ Thus the MoÐI bond lengths are 1[894 "1#\ 1[813 with the structures shown in Figs 0 and 1[ The 02C

2351
N[ G[ Aimeloglou et al[
Fig[ 1[ Crystal structure of ðMoI1"CO#"NCMe#"h1!PhC1Ph#1Ł\ showing the atom numbering scheme[ Ellipsoids shown at
49) probability[
NMR spectrum of complex 0 has alkyne contact "for XꢁI\ y"CO#ꢁ1919 and 0855 cm−0^ for XꢁBr\
carbon resonances at dꢁ057[9 and 048[9 ppm\ which y"CO#ꢁ1912 and 0876 cm−0# were observed after
conforms with the two alkyne ligands donating a total 1 hrs "for 0# and 0 hr "for 1# respectively[ This might
of six!electrons to the molybdenum ð0Ł\ which enables be explained by the smaller size of the bromide ligands
the complex to obey the e}ective atomic number rule[ enabling more rapid formation of the dimeric
It should be noted that we reported the mono"ace! complex[ It should be noted that Davidson and
tonitrile# complex ðMoI1"CO#"NCMe#"h1!MeC1Me#1Ł Vasapollo ð11Ł described the reactions of RC1R
"0# {could not be isolated in a pure state| ð09Ł[ When "RꢁMe\ Et\ Ph# with ð"W"m!Br#Br"CO#3#1Ł to give
reinvestigating this reaction we found that reaction the bromide!bridged dimers ð"W"m!Br#Br"CO#"h1!
of ðMoI1"CO#2"NCMe#1Ł with excess but!1!yne gave RC1R#1#1Ł\ which were fully characterised\ and are
high yields of pure complex 0[ As we have previously analogous to the dimers\ ð"Mo"m!X#X"CO#"h1!
observed complex 0 reacts in CH1Cl1 at room tem! MeC1Me#1#1Ł "XꢁBr\ I# described in this paper[ The
perature "06 hrs# to a}ord the dimeric complex spectroscopic properties of the ð"Mo"m!X#X"CO#"h1!
ð"Mo"m!I#I"CO#"h1!MeC1Me#1#1Ł[ The ease of dim! MeC1Me#1#1Ł "XꢁBr\ I# and ð"W"m!Br#Br"CO#"h1!
erisation of complexes 0 and 1 was investigated by RC1R#1#1Ł "RꢁMe\ Et\ Ph# ð11Ł complexes are very
IR spectroscopy[ The room temperature reactions of similar[
ðMoX1"CO#2"NCMe#1Ł "XꢁI\ Br# with four equi!
valents of but!1!yne in CHCl2 were followed by IR ðMoI1"CO#"L+L#"h1!RC1Ph#Ł complexes
spectroscopy[ Complete dimerisation of the initially
formed bis"alkyne# complexes ðMoX1"CO#"NCMe#
The reactions of ðMoI1"CO#"NCMe#"h1!RC1Ph#1Ł
"h1!MeC1Me#1Ł to ð"Mo"m!X#X"CO#"h1!MeC1Me#1#1Ł with neutral and anionic ligands described in this

Halocarbonyl alkyne complexes of molybdenum"II#
2352
Scheme 0
All reactions were carried out in CH1Cl1[
"i# RꢁPh\ N+Nꢁ4\5!Me1!0\09!phen^ RꢁMe\ N+Nꢁ1\1?!bipy^
"ii# RꢁPh\ P+PꢁPh1P"CH1#1PPh1^ RꢁMe\ P+PꢁPh1P"CH1#nPPh1\ nꢁ0\ 2\ 3^
"iii# RꢁMe^ 1NaðS1CNMe1Ł[
paper are given in Scheme 0[ Equimolar quantities of phen#"h1!PhC1Ph#Ł "7# have been grown from a con!
ðMoI1"CO#"NCMe#"h1!RC1Ph#1Ł and L+L in CH1Cl1 centrated CDCl2 solution of 7 in an NMR tube for
react at room temperature to give the neutral mono one week[ The molecular structure of ðMoI1"CO#"4\5!
"alkyne# complexes ðMoI1"CO#"L+L#"h1!RC1Ph#Ł Me1!0\09!phen#"h1!PhC1Ph#Ł "7# is shown in Fig[ 2
"RꢁPh\ L+Lꢁ4\5!Me1!0\09!phen^ Ph1P"CH1#1PPh1\ together with the atomic numbering scheme and can
RꢁMe\ L+Lꢁ1\1?!bipy\ Ph1P"CH1#nPPh1 "nꢁ0\ 2\ also best be described as a distorted octahedron in
3## "7:02# in high yield[ All complexes 7:02 have which the PhC1Ph ligand occupies one site which is
been characterised as shown in Tables 2:4[ Com! trans! to an iodide[ The second iodide is trans! to a
plexes 7:02 are generally more stable\ but less soluble nitrogen atom of the phenanthroline ligand\ while the
that their bis"alkyne# precursors 0:6[
carbonyl group is trans to the other nitrogen atom[
It is interesting to note ð12Ł that reaction of the There is half a molecule of CDCl2 per unit formula of
analogous tungsten complexes ðWI1"CO#"NCMe#"h1! 7 in the crystal lattice since suitable single crystals for
RC1R#1Ł "RꢁMe\ Ph# react with an equimolar X!ray analysis were grown from CDCl2[ Complex 7\
amount of N+N "N+Nꢁ1\1?!bipy\ 0\09!phen# to prepared in CH1Cl1 does not have a molecule of sol!
a}ord the cationic bis"alkyne# complexes ðWI"CO# vent as shown by elemental analysis "C\ H and N#
"N+N#"h1!RC1R#1ŁI\ which was crystallographically Table 2 and 0H NMR spectroscopy Table 4[ It is
characterised for N+Nꢁ1\1?!bipy\ RꢁMe\ as its interesting that the two MoÐI bond lengths are con!
ðBPh3Ł! salt[ It is well known that low valent molyb! siderably shorter than in
0
and ðMoI1"CO#
1
Ä
denum organometallic complexes are much more "NCMe#"h !PhC1Ph#1Łð1[723 "1#\ 1[757 "1# AŁ but pre!
labile than their analogous tungsten compounds[ This sumably this is due to a decrease in strain as the angle
probably accounts for the greater lability of the alkyne subtended at the metal by the two iodides is 89[0>
ligand bonded to molybdenum[ However\ reaction of compared to 72[4 "0#\ 73[1 "0#> in "0# and ðMoI1"CO#
ðWI1"CO#"NCMe#"h1!RC1R#1Ł "RꢁMe\ Ph# with an "NCMe#"h1PhC1Ph#1Ł respectively[
0
equimolar quantity of Ph1P"CH1#nPPh1 "nꢁ0:5# in
The H NMR data "Table 4# for complexes 7:02
CH1Cl1 at room temperature yields the mono"alkyne# comply with the formulation of the complexes[ Since
complexes ðWI1"CO#"Ph1P"CH1#nPPh1#"h1!RC1R#Ł we have previously described ð00Ł the synthesis and
ð00Ł\ ie[ analogous to the molybdenum reactions[ The structure of the but!1!yne complex ðWI1"C!
infra red spectra of 7:02 all show a single carbonyl O#"Ph1P"CH1#PPh1#"h1!MeC1Me#Ł\ we tried to grow
band between 0836 and 0866 cm−0[ Alkyne stretching single crystals of complexes 8\ 01 and 02[ Suitable
bands are also observed at considerably lower wave! single crystals of ðMoI1"CO#"Ph1P"CH1#1PPh1#"h1!
number compared to the free alkyne[
PhC1Ph#Ł "8# were grown and subjected to X!ray
Single crystals of ðMoI1"CO#"4\5!Me1!0\09! analysis[ The data collected were poor\ however the

2353
N[ G[ Aimeloglou et al[
Fig[ 2[ Crystal structure of ðMoI1"CO#"4\5!Me1!0\09!phen#"h1!PhC1Ph#Ł "7#\ showing the atom numbering scheme[ Ellipsoids
shown at 29) probability[
basic coordination geometry for the structure is shown "S1CNEt1#1"h1!RC1R?#Ł "RꢁR?ꢁH\ Ph of CO1Me^
in Fig[ 3 and is discussed in a footnote0[
RꢁH\ R?ꢁMe or Ph^ RꢁMe\ R?ꢁPh# ð13\14Ł\
ðMo"CO#"S1PiPr1#1"h1!HC1H#Ł
ð15\16Ł
ðW"CO#
"S1CNEt1#1"h1!RC1R?#Ł "RꢁR?ꢁH\ Me\ Et or Ph^
RꢁH\ P?ꢁPh# ð17\18Ł ðMo"CO##"S1CNR1#"h1!
C7H01#Ł "MꢁMo W^ RꢁMe or Ph# ð29Ł and
ðMo"CO#"S1CNMe1#1"h1!MeC1Ph#Ł "03# complex
Treatment of ðMoI1"CO#"NCMe#"h1!MeC1Ph#1Ł
with two equivalents of NaS1CNMe1 in CH1Cl1 at
room temperature gives the mono"alkyne# complex
ðMo"CO#"S1CNMe#1"h1!MeC1Ph#Ł "03#[ Complex 03
has been fully characterised in the normal manner
"see Tables 2:4#[ The bis"dithiocarbamate# complex
ðMo"CO#"S1CNMe1#1"h1!MeC1Ph#Ł is closely related
to the previously reported complexes ðMo"CO#
ðW"CO#"L+L?#1"h1!RC1R?#Ł
"RꢁR?ꢁMe\
L+L?ꢁS1CNMe1 or 1!SC4H3N^ RꢁPh\ R?ꢁMe\
L+L?ꢁS1CNMe1
or
S1PMe1^
RꢁR?ꢁPh\
L+L?ꢁS1PMe1# ð20Ł[ Since the spectral properties of
03 are similar to the crystallographically characterised
complex ðW"CO#"S1CNEt1#1"h1!HC1H#Ł ð17Ł\ the
structure of 03 is likely to be similar as shown in
Fig[ 4[
0Data for "8#\ ðMoI1"CO#"Ph1P"CH1#1PPh1#"h1!PhC1Ph#Ł\
CONCLUSIONS
C30H27I1MoP1\ Mꢁ847[3\ aꢁ00[222 "8#\ bꢁ12[69 "1#\
2
Ä
Ä
Cꢁ03[889 "01# A\ bꢁ096[49 "0#\ Uꢁ2728 A \ monoclinic\
spacegroup P10:c\ Zꢁ3[ The crystals gave a highly dis!
ordered di}raction pattern\ and while the structure was
determined\ it is of insu.cient quality to be reported here
in detail[ The molybdenum atom occupies an octahedral
environment being bonded to two phosphorus atoms trans
to iodide and the carbonyl group\ and a diphenylalkyne trans
to the second iodide group[ The arrangement of ligands is
thus di}erent from that observed in ðWI1"CO#"Ph1P"CH1#
PPh1#"h1!MeC1Me#Ł ð00Ł where the alkyne is trans to one of
the phosphorus atoms and the iodide groups are trans to the
remaining phosphorus atom and the carbonyl group[
Although the bis"alkyne# complexes of molyb!
denum"II# ðMoXX?"CO#"NCMe#"h1!RC1R?#1Ł are less
stable than their tungsten analogues\ they can be iso!
lated and their chemistry studied[ Many of the reac!
tions of the molybdenum and tungsten bis"alkyne#
complexes ðMXX?"CO#"NCMe#"h1!RC1R?#1Ł are very
similar\ however their reactions with bidentate nitro!
gen donors are quite di}erent[ For example\ the reac!
tion of ðMI1"CO#"NCMe#"h1!MeC1Ph#1Ł with 1\1?!
bipy gives the cationic bis"alkyne# tungsten complex
ðWI"CO#"1\1?!bipy#"h1!MeC1Ph#1ŁI ð12Ł and the

Halocarbonyl alkyne complexes of molybdenum"II#
2354
Fig[ 3[ Ortep picture of ðMoI1"CO#"Ph1P"CH1#1PPh1#"h1!PhC1Ph#Ł "8#[ Ellipsoids shown at 29) probability[
assistance with the crystallographic investigations and the
EPSRC and the University of Reading for funds for the
Image Plate System[
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"h1!MeC1Ph#Ł "03#
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Acknowled`ements*M[M[M[ thanks the EPSRC for
studentship and N[G[A[ thanks the Training for Work
scheme for support[ We also thank A[W[ Johans for his
a

2355
N[ G[ Aimeloglou et al[
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Or`anomet[ Chem[\ 0875\ 298\ 208[
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11[ Davidson\ J[ L[ and Vasapollo\ G[\ J[ Chem[ Soc[\
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12[ Baker\ P[ K[\ Armstrong\ E[ M[ and Drew\ M[ G[
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03[ Baker\ P[ K[\ Birkbeck\ T[\ Brase\ S[\ Bury\ A[
Ã
and Naylor\ H[ M[\ Transition!Met[ Chem[\ 0881\
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04[ Baker\ P[ K[\ Flower\ K[ R[\ Naylor\ H[ M[ and
Voigt\ K[\ Polyhedron\ 0882\ 01\ 246[
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08[ Shelxl\ Sheldrick\ G[ M[\ program for crystal
structure re_nement\ University of Gottingen\
Ã
0882[
19[ Baker\ P[ K[\ Muldoon\ D[ J[\ Lavery\ A[ J[ and
Shawcross\ A[\ Polyhedron\ 0883\ 02\ 1804[