New dithiocarbamate compounds of manganese carbonyl and a zinc polymer

Article abstract of DOI:10.1016/S0277-5387(98)00064-3

The reaction of [EtO₂CN=CS₂C {N (H) CO₂Et} {S₂CN (H) CO₂Et} ] , 1 with Mn₂ (CO) ₉NCMe yielded the dithiocarbamate complex Mn (CO) ₄ [S₂CN (H) CO₂Et] , 2 which was characterized structurally in the form of its phosphine derivative Mn (CO) ₃ (PMe₂Ph) [S₂CN (H) CO₂Et] , 3. Compound 3 was found to contain a chelating dithiocarbamato ligand with a cis-positioned phosphine ligand. Compound 1 also reacts with zinc acetylacetonate to yield the zinc dithiocarbamate complex Zn (μ-S,S-S₂CN (H) CO₂Et) (μ-O,S-S₂CN (H) CO₂Et) , 4. Compound 4 forms a helical polymer in the solid state with the zinc ions linked by bridging dithiocarbamate ligands. Compound 1 appears to be a good source of the ethoxycarbonylthiocarbamate ligand.

Full text of DOI:10.1016/S0277-5387(98)00064-3

Polyhedron Vol[ 06\ No[ 05\ pp[ 1648Ð1653\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII ] S9166Ð4276"87#99953Ð2
New dithiocarbamate compounds of manganese
carbonyl and a zinc polymer
Richard D[ Adamsꢀ and Mingsheng Huang
Department of Chemistry and Biochemistry\ University of South Carolina\ Columbia\ SC 18197\ U[S[A[
"Received 02 November 0886 ^ accepted 15 January 0887#
Abstract*The reaction of ðEtO1CN1CS1C"N"H#CO1Et#"S1CN"H#CO1Et#Ł\ 0 with Mn1"CO#8NCMe yielded
the dithiocarbamate complex Mn"CO#3ðS1CN"H#CO1EtŁ\ 1 which was characterized structurally in the form
of its phosphine derivative Mn"CO#2"PMe1Ph#ðS1CN"H#CO1EtŁ\ 2[ Compound 2 was found to contain a
chelating dithiocarbamato ligand with a cis!positioned phosphine ligand[ Compound 0 also reacts with zinc
acetylacetonate to yield the zinc dithiocarbamate complex Zn"m!S\S!S1CN"H#CO1Et#"m!O\S!S1CN"H#CO1Et#\
3[ Compound 3 forms a helical polymer in the solid state with the zinc ions linked by bridging dithiocarbamate
ligands[ Compound 0 appears to be a good source of the ethoxycarbonylthiocarbamate ligand[ Þ 0887 Elsevier
Science Ltd[ All rights reserved
Keywords] dithiocarbamate ligand ^ manganese ^ zinc ^ polymer[
———————————————————————————————————————————————
We have recently obtained the new compound
In this report we describe reaction of the compound
"EtO1CN1CS1CðN"H#CO1EtŁðS1CN"H#CO1EtŁ#\ 0 0 with Mn1"CO#8"MeCN# and zinc acetylacetonate[
from the reaction of water with ethoxy! We have found that compound 0 readily transfers its
carbonylisothiocyanate ð0Ł[ Compound 0 can be dithiocarbamate grouping to the metal atoms to yield
viewed as an adduct of a dimer A of the isothiocyanate new metal compounds[
and the dithiocarbamic acid\ EtO1CNHCS1H[ Iso!
thiocyanates are e}ective ligands for the transition
metals ð1\2Ł[ They have been shown to coordinate
in h1!C0S\ B and bridging m!h1!C0S\ C and m!h2!
N0C0S\ D bonding modes between two metal
atoms[ Dithiocarbamate anions are also good ligands
for the transition metals and a large number of com!
plexes have been made by employing them ð3Ł[
EXPERIMENTAL
Unless speci_ed otherwise\ all reactions were per!
formed under an atmosphere of nitrogen[ All solvents
were appropriately dried and degassed prior to use[
Zinc acetylacetonate was purchased from Strem and
was used without further puri_cation[ TLC sep!
arations were performed in air by using silica gel "59
_\ F143# on plates "Whatman\ 9[14 mm#[ Elemental
analyses were performed by Desert Analytics\ Tucson\
AZ[ Mass spectra were carried out on a VG Model
ꢀ Author to whom correspondence should be addressed[
1648

1659
R[ D[ Adams and M[ Huang
69SQ mass spectrometer "direct inlet\ electron impact Preparation of Zn"S1CNHCO1Et#1\ 3
ionization#[ "EtO1CN1CS1CðN"H#CO1EtŁðS1CN"H#
CO1EtŁ#\ 0 which contains one equivalent of cocrys!
"a# To a 04 ml three necked ~ask was added a 49[9
tallized EtO1CN1C1S was prepared as previously mg amount "9[978 mmol# of 0 = "EtO1CN1C1S#\ a
described ð0Ł[ Mn1"CO#8"MeCN# was prepared by the 49[9 mg amount "9[075 mmol# of Zn"acac#1 and 4 ml
reported method ð4Ł[
of CH1Cl1[ The mixt was stirred at room temperature
for 07 h[ The mixt was _ltered and washed with 1×9[4
ml of ethylacetate[ The _ltrate and the washings were
combined and the solvent removed[ The resulting resi!
due was separated by TLC using silica gel thin plates
without ~uorescent indicator and a 0:2 hexane:
CH1Cl1 solvent mixt[ This yielded 00[1 mg of Zn
Reaction of 0 with Mn1"CO#8"MeCN#
An 78[9 mg amount "9[048 mmol# of
0 = "EtO1CN1C1S# was added to a soln of a 14[9 mg
amount "9[951 mmol# of Mn1"CO#8"MeCN# in 09 ml
of hexane[ The mixt was stirred at room temp[ for 3
days[ The volatiles were removed under vacuum\ and
the residue was separated by TLC using a 2:0 hex!
ane:CH1Cl1 solvent mixt[ This yielded Mn1"CO#09\
"0[6 mg# and yellow Mn"CO#3ðS1CN"H#CO1EtŁ\ 1
"07[5 mg\ 34) yield#[ Spectral data for 1 ] IR "nCO in
hexane\ cm−0# ] 1981 "m#\ 1903 "s#\ 1992 "s#\ 0855 "s#\
0666 "w\ br#\ 0648 "w\ br#[ 0H NMR "d in C5D5\ ppm# ]
"m!S\S!S1CN"H#CO1Et#"m!O\S!S1CN"H#CO1Et#\
3
"46) yield based on 0#[ Spectra data for 3 ] 0H NMR
"d in CDCl2\ ppm# ] 8[94 "s\ br\ 1H\ NH#\ 3[29 "q\
2
2JHÐH ꢁ 6[0 Hz\ 3H\ OCH1Me#\ 0[22 "t\ JHÐH ꢁ 6[0
Hz\ 5H\ CH2#[ Anal ] Calcd "found# ] C\ 13[39 "13[34# ^
H\ 2[96 "1[75# ^ N\ 6[00 "6[90#[
"b#
A 29[9 mg amount "9[943 mmol# of
0 = "EtO1CN1C1S# was dissolved in a minimum
amount of CH1Cl1[ The soln was loaded on TLC
plates "silica gel with Zn1SiO3 ~uorescent indicator#[ A
pale yellow band was eluted with a 2:0 CH1Cl1:hexane
solvent mixt to yield 3[7 mg of 3 "34) yield#[
2
6[34 "s\ br\ 0H\ NH#\ 2[52 "q\ JHÐH ꢁ 6[1 Hz\ 1H\
2
OCH1Me#\ 9[62 "t\ JHÐH ꢁ 6[0 Hz\ 2H\ CH2#[ MS ]
parent ion m:e ꢁ 220 plus ions corresponding to the
loss of each of the four carbonyl ligands[
Reaction of 1 with PMe1Ph
Crystallo`raphic analyses
A 08[0 mg amount "9[947 mmol# of 1 and 8[9 ml
Crystals of 2 suitable for X!ray di}raction analysis
amount "9[005 mmol# of dimethylphenylphosphine were obtained by slow evaporation of solvent from a
were dissolved in 14 ml of hexane[ The soln was heated hexane soln at −3>C[ Crystals of 3 suitable for X!ray
to re~ux for 29 min[ After the solvent was removed di}raction analysis were obtained by slow evap!
via rotary evaporation\ the residue was separated by oration of solvent from a 0:2 acetone:acetonitrile soln
TLC using a 0:0 hexane:CH1Cl1 solvent mixt[ This at 14>C[ The crystals used in intensity measurements
yielded
a
yellow
band
of
Mn"CO#2"P! were mounted in thin!walled glass capillaries[
Me1Ph#ðS1CN"H#CO1EtŁ\ 2 "11[0 mg\ 76) yield#[ Di}raction measurements for 2 were made on a
Spectral data for 2 ] IR "nCO in hexane\ cm−0# ] 1915 Rigaku AFC5S fully automated four!circle di}ract!
"vs#\ 0836 "s#\ 0806 "s#\ 0662 "w\ br#\ 0640 "w\ br#[ 0H ometer using graphite!monochromated MoÐKa radi!
NMR "d in CDCl2\ ppm# ] 7[94 "s\ br\ 0H\ NH#\ 6[31 ation[ Di}raction measurements for 3 were made on
2
"m\ 4H\ C5H4#\ 3[19 "q\ JHÐH ꢁ 6[9 Hz\ 1H\
a Rigaku AFC4R fully automated four!circle
2
OCH1Me#\ 0[71 "d\ JHÐH ꢁ 7[0 Hz\ 5H\ P"CH2#1#\ di}ractometer using graphite!monochromated CuÐKa
0[18 "t\ JHÐH ꢁ 6[9 Hz\ 2H\ OCH1CH2#[ Anal ] Calc[ radiation[ The unit cells were determined and re_ned
2
"found# ] C\ 39[71 "39[66# ^ H\ 2[77 "2[40# ^ N\ 2[06 from 04 randomly selected re~ections obtained by
"2[19#[
using the AFC5S or AFC4R automatic search\ center\

Compounds of manganese carbonyl and a zinc polymer
1650
Table 0[ Crystal data for compounds 2 and 3
Compound
Formula
Formula weight
Crystal system
a "_#
2
3
MnS1PO4NC04H06
330[22
Monoclinic
00[488"1#
09[583"0#
05[392"1#
85[46"0#
1910[0"3#
P10:c "è03#
3
ZnS3O3N1C7H01 = MeCN
323[76
Monoclinic
03[632"1#
6[830"0#
04[294"0#
80[19"0#
0680[3"2#
P10:c "è03#
3
b "_#
c "_#
b ">#
V "_2#
Space group
Z value
rcalc "g:cm2#
m"MoÐKa# "cm−0
1Umax ">#
0[34
8[50
37
1598
0[50
53[20 "CuÐKa#
019
#
No[ obs[ "I × 2s#
1900
No[ variables
120
1[47
9[91
9[923 ^ 9[939
Difabs
0[99:9[65
9[21
197
1[45
9[94
9[932 ^ 9[937
empirical
0[99:9[26
9[67
Goodness of _t "GOFa#
Max shift in _nal cycle
Residualsa ] R ^ Rw
Abs[ cor[
Transmis coe} max:min
Largest residual pk "e:_2#
a R ꢁ Shkl">Fobs=−=Fcalc>#:Shkl=Fobs= ^
Rw ꢀ ðShklw"=Fobs=−=Fcalc=#1:ShklwFo1bsŁ0:1
\
w ꢁ 0:s1"Fobs# ^
GOF ꢁ ðShklw"=Fobs=−=Fcalc=#1:"ndata−nvari#Ł0:1
[
index\ and least!squares routines[ Crystal data\ data positions were not re_ned[ One equivalent of MeCN
collection parameters\ and results of these analyses are from the crystallization solvent was found cocrys!
listed in Table 0[ All data processing was performed tallized in the lattice[ This was included in the cal!
on a Silicon Graphics Indigo1 computer by using the culations and was satisfactorily re_ned with 099)
TEXSAN structure solving program library obtained occupancy[
from the Molecular Structure Corp[\ The Woodlands\
TX[ Neutral atom scattering factors were calculated
by the standard procedures ð5aŁ[ Anomalous dis!
RESULTS AND DISCUSSION
persion corrections were applied to all non!hydrogen
When compound 0 was allowed to react with
atoms ð5bŁ[ Lorentz!polarization "Lp# and absorption
Mn1"CO#8"MeCN# in a hexane soln at 14>C for 3
corrections were applied in each analysis[ Full matrix
days\ the compound 1 was formed in 34) yield[ A
least!squares re_nements minimized the function ]
manganese pentacarbonyl grouping was eliminated in
S
hklw"=Fo=−=Fc=#1\ where w ꢁ 0:s"F#1\ s"F#
ꢀ
the process\ presumably as HMn"CO#4[ HMn"CO#4 is
relatively unstable and was not recovered from the
reaction[ The formula of compound 1 was established
by a combination of IR\ 0H NMR\ mass spectral and
elemental analyses[ The structure proposed for 1 is
based largely on a single crystal X!ray di}raction
analysis of the PMe1Ph derivative fac!Mn"CO#2"P!
Me1Ph#ðS1CN"H#CO1EtŁ\ 2 that was obtained by the
reaction of 1 with PMe1Ph[ Compound 2 is obtained
in 76) yield after 29 min at re~ux in a hexane soln\
eqn "0#[
s"F1o#:1Fo\
"9[91 = Inet#1Ł0:1:Lp[
and
s"F1o #
ꢁ
ðs"Iraw#1¦
Compounds 2 and 3 crystallized in the monoclinic
crystal system[ The patterns of systematic absences
observed during the collection of intensity data ident!
i_ed the space group uniquely as P10:c for compounds
2 and 3[ For 2 the hydrogen atom "H# on the nitrogen
atom N was located and re_ned with isotropic thermal
parameters[ The positions of all other hydrogen atoms
were calculated by assuming idealized geometries with
all C0H distances at 9[84 _[ Their contributions were
added to the structure factor calculations\ but their
Compound
2
was characterized crystallo!
positions were not re_ned[ For 3 the hydrogen atoms graphically and an ORTEP diagram of the molecular
H"0# and H"1# on the nitrogen atoms N"0# and N"1# structure is shown in Fig[ 0[ Compound 2 is a six coor!
were located and re_ned with isotropic thermal par! dinate complex[ It contains three COs\ one PMe1Ph
ameters[ The positions of all other hydrogen atoms and one S1CN"H#CO1Et ligand[ The three CO ligands
were calculated by assuming idealized geometries with are arranged in a fac!form[ This is consistent with
all C0H distances at 9[84 _[ Their contributions were three strong absorptions in the IR spectrum in solu!
added to the structure factor calculations\ but their tion\ 1915 "vs#\ 0836 "s#\ 0806 "s# cm−0[ The dithio!

1651
R[ D[ Adams and M[ Huang
transient Mn"CO#4 anion formed by cleavage of
the Mn0Mn bond to yield HMn"CO#4[
Compound 0 was also found to react with Zn"acac#1
in CH1Cl1 solvent at 14>C over a period of 07 h to
produce
a
new
compound
Zn"m!S\S!
S1CN"H#CO1Et#"m!O\S!S1CN"H#CO1Et#\ 3 in 46)
yield[ It is even formed "34) yield# simply by eluting 0
over TLC plates containing the Zn1"SiO3# ~uorescent
indicator[ Compound 3 was characterized by a single!
crystal X!ray di}raction analysis[ The compound
exists in a polymeric form in the solid state[ An
ORTEP diagram showing a portion of one polymeric
chain of the structure is shown in Fig[ 1[ The ZnSCS
linkage of the polymer is indicated by the solid bonds[
In compound 3\ one dithiocarbamato ligand is che!
lated to the zinc atom via the two sulfur atoms S"0#
and S"1#[ This ligand is not involved in the polymeric
Fig[ 0[ An ORTEP diagram of Mn"CO#2"P!
Me1Ph#"S1CNHCO1Et#\ 2[ Selected interatomic distances
"_# and angles "># are ] Mn0S"0# ꢁ 1[2771"7#\ Mn0S"1#
ꢁ 1[2740"8#\ Mn0P ꢁ 1[2443"8#\ S"0#0C"0# ꢁ 0[693"2#\ linkage[ The Zn0S"0# distance of 1[560"1# _ is sig!
S"1#0C"0# ꢁ 0[567"2#\ C"0#0N ꢁ 0[252"3#\ C"1#0N ꢁ
0[289"3#\ C"1#0O"0# ꢁ 0[080"3#\ C"1#0O"1# ꢁ 0[226"3# ^
ni_cantly longer than the Zn0S"1# distance\ 1[234"1#
_[ This may be related to the coordination geometry
and bonding about the zinc ion\ see below[ The poly!
meric chain is formed via the coordination of the
second dithiocarbamate ligand[ The sulfur atom S"3#
is bonded to one zinc atom\ Zn0S"3# ꢁ 1[231"1# _\
while the other sulfur atom S"2# is bonded to another
zinc atom\ Znꢀ0S"2# ꢁ 1[215"1# _[ This coor!
dination leads to the formation of an helical in_nite
chain along b!direction of the unit cell[ In addition\
the carbonyl oxygen atom O"2# of the carboxylate
group is also coordinated to zinc[ This results in the
S"0#0C"0#0S"1#
ꢁ
003[1"1#\ N"0#0C"0#0S"0#
ꢁ
007[8"1#\ N"0#0C"0#0S"1# ꢁ 015[7"1#\ C"0#0N"0#0C"1#
ꢁ 016[0"2#[
carbamato ligand is chelated to the metal atom via the
two sulfur atoms[ The Mn0S distances are essentially
identical\ Mn0S"0# ꢁ 1[2771"7# _\ Mn0S"1# ꢁ
1[2740"8# _\ and are similar to those found in the
related complex Mn"CO#2"PPh2#"S1CNMe1#\ 4\ 1[262Ð
1[274 _ ð6Ł[ The carbonÐsulfur distances are very simi!
lar in length C"0#0S"0# ꢁ 0[693"2# _\ C"0#0S"0# ꢁ
0[567"2# _ and are similar to those found in com!
pound 4\ 0[535Ð0[695 _[ The hydrogen atom on the
nitrogen atom was located crystallographically and its
formation of
a
six membered metallocycle\
Zn0S"2#0C"2#0N"1#0C"3#0O"2#[ The zinc atom
has a _ve!coordinate distorted trigonal bipyramidal
geometry[ The equatorial sites are occupied by the
sulfur atoms S"1#\ S"2# and S"3#[ The axial sites are
occupied by the atoms S"0# and O"2#[ Both zinc!ligand
axial bonds are unusually long\ Zn0S"0# ꢁ 1[560"1#
_ and Zn0O"2# ꢁ 1[043"1# _[ Zinc has been found
in distorted trigonal bipyramidal environments in the
related _ve coordinate dithiocarbamate complexes
Zn"S1CNEt1#1 ð7Ł and Zn"py#"S1CNMe1#1 = 9[4C5H5
ð8Ł[ In both cases the axial Zn0S bond distances are
signi_cantly longer than the equatorial Zn0S bond
distances[ The Zn0O"2# bond distance is signi_cantly
longer than those found in related carboxylate com!
0
resonance was observed in the H NMR spectrum as
a broad singlet at d ꢁ 7[94 ppm[
We anticipate that the formation of 1 has occurred
by the transfer of the dithiocarbamate ion from 0 to
the Mn1"CO#8"NCMe# through cleavage of the car!
bonÐsulfur bond and a nucleophilic displacement of
the NCMe ligand from the manganese complex by
the dithiocarbamate[ Although this could occur via a
mechanism involving radicals\ we prefer a mechanism plexes ðNBun3 ðZn"S1CNEt1#1 "O1CMe#Ł\ 0[868"5# _
based on two electron processes as shown in the ð09Ł and Zn"O1CCH1CH2#1\ 0[84 _ ð00Ł[ In the solid
Scheme which culminates with a protonation of a state\ the two dithiocarbamato ligands in 3 are inequi!

Compounds of manganese carbonyl and a zinc polymer
1652
Scheme 0[
Fig[ 1[ An ORTEP diagram showing a portion of the polymeric chain Zn"m!S\S!S1CN"H#CO1Et#"m!O\S!S1CN"H#CO1Et#\
3[ The connectivity of the ZnSCS polymer is indicated by the solid bonds[ Selected interatomic distances "_# and angles ">#
are ] Zn0S"0# ꢁ 1[560"1#\ Zn0S"1# ꢁ 1[2340"1#\ Zn0S"2# ꢁ 1[215"1#\ Zn0S"3# ꢁ 1[231"1#\ Zn0O"2# ꢁ 1[043"3#\
S"0#0C"0# ꢁ 0[567"5#\ S"1#0C"0# ꢁ 0[693"4#\ S"2#0C"2# ꢁ 0[571"4#\ S"3#0C"2# ꢁ 0[580"4#\ C"0#0N"0# ꢁ 0[260"6#\
C"1#0N"0# ꢁ 0[394"6#\
C"2#0N"1# ꢁ 0[254"6#\
C"3#0N"1# ꢁ 0[268"6#\
C"3#0O"2# ꢁ 0[101"5# ^
S"0#0Zn0S"1# ꢁ 60[53"4#\ S"0#0Zn0S"2# ꢁ 89[95"4#\ S"0#0Zn0S"3# ꢁ 89[52"4#\ S"0#0Zn0O"2# ꢁ 050[3"0#\
S"1#0Zn0S"2# ꢁ 010[32"5#\ S"1#0Zn0S"3# ꢁ 096[17"5#\ S"1#0Zn0O"2# ꢁ 83[3"0#\ S"2#0Zn0S"3# ꢁ 096[57"6#\
S"2#0Zn0O"2# ꢁ 75[8"0#\ S"3#0Zn0O"2# ꢁ 094[5"0#\ S"0#0C"0#0S"1# ꢁ 010[2"2#\ S"2#0C"0#0S"3# ꢁ 010[8"2#[
valent\ however\ only one set of resonances for the solution[ Other zinc dithiocarbamates\ Zn"S1CNEt1#1
ethyl groups and only one for the hydrogen atom ð7Ł and Zn"S1CNMe1#1 ð01Ł have been found to form
bonded to two nitrogen atoms\ 8[94 "s\ br\ 1H\ NH#\ dimeric units in solid state\ but they exist in mono!
0
are observed in the H NMR spectrum in solution[ meric forms in solution[
This suggests that compound 3 depolymerizes when
The formation of compound 3 also appears to be
dissolved in chloroform solvent\ and the two dithi! the result of transfer of the dithiocarbamate grouping
ocarbamato ligands are either structurally equivalent of 0 to a zinc ion[ Zinc and other dithiocarbamates
or are dynamically averaged on the NMR time scale in have been used for a variety of purposes ranging from

1653
R[ D[ Adams and M[ Huang
88\ 1007 ^ "d# Bianchini\ C[\ Masi\ D[ and Meli\
A[\ J[ Or`anomet[ Chem[\ 0872\ 136\ C18[
2[ Adams\ R[ D[ and Huang\ M[\ Or`anometallics\
0885\ 04\ 2533[
3[ "a# Coucouvanis\ D[\ Pro`[ Inor`[ Chem[\ 0868\
15\ 290 ^ "b# Coucouvanis\ D[\ Pro`[ Inor`[ Chem[\
0869\ 00\ 122[
4[ Koelle\ U[\ J[ Or`anomet[ Chem[\ 0867\ 044\ 42[
5[ "a# International Tables for X!ray Crys!
tallo`raphy\ Vol[ IV[ Kynoch Press\ Birmingham\
England\ 0864\ Table 1[1b\ pp[ 88Ð090 ^ "b# Ibid[\
Table 1[2[0\ pp[ 038Ð049[
6[ Dean\ W[ K[ and Moncrief\ J[ W[\ J[ Coord[
Chem[\ 0865\ 5\ 096[
7[ Bonamica\ M[\ Mazzone\ G[\ Vaciago\ A[ and
Zambonelli\ L[\ Acta Cryst[\ 0854\ 08\ 787[
8[ Fraser\ K[ A[ and Harding\ M[\ Acta Cryst[\ 0856\
11\ 64[
09[ McCleverty\ J[ A[\ Spencer\ N[\ Bailey\ N[ A[ and
Shackleton\ S[\ J[ Chem[ Soc[\ Dalton Trans[\
0879\ 0828[
pesticides to rubber vulcanization accelerators ð02Ł[ In
summary it appears that 0\ which is very easily
obtained from ethoxycarbonylisothiocyanate\ is a
convenient source of the ethoxycarbonyldithio!
carbamate[
Supplementary material ] Tables of _nal atomic pos!
itional parameters\ bond distances\ bond angles and
anisotropic thermal parameters are available for the
structural analysis of 2 and 3 "00 pages# have been
deposited with the Cambridge Crystallographic Data
Centre[ Support for an upgrade of the NMR facilities
at the University of South Carolina was provided by
an NSF ARI grant\ Grant No[ CHE!8590612[
Acknowled`ments*These studies were supported by the Div!
ision of Chemical Sciences of the O.ce of Basic Energy
Sciences of the U[S[ Department of Energy[ The authors
wish to thank Prof[ F[ A[ Cotton and Dr Lee Daniels for
measurement of the di}raction intensity data for compound
3[
00[ Goldschmied\ E[ and Rae\ A[ D[\ Acta Cryst[\
0866\ B22\ 1006[
01[ Klug\ H[ P[\ Acta Cryst[\ 0855\ 10\ 425[
02[ "a# McCleverty\ J[ A[\ Morrison\ N[\ Spencer\ N[\
Ashworth\ C[ C[\ Bailey\ N[ A[\ Johnson\ M[ R[\
Smith\ J[ M[ A[\ Tabbiner\ B[ A[\ Taylor\ C[ R[
and Shackleton\ S[\ J[ Chem[ Soc[\ Dalton Trans[\
0879\ 0834 ^ "c# Ashworth\ C[ C[\ Bailey\ N[ A[\
Johnson\ M[ R[\ McCleverty\ J[ A[\ Morrison\ N[
and Tabbiner\ B[ A[\ J[ Chem[ Soc[\ Chem[
Comm[\ 0865\ 632[
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