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Group VIb metal carbonyl complexes of 1,3-dithiolene-2-thione
INORG.
NUCL.
CHEM.
LETTERS
Vol.
11,
pp.
345-347,
1975.
Pergamon
Press.
Printed
in
Great
Britain.
GROUP VIb METAL CARBONYL COMPLEXES OF 1,3-DITHIOLENE-2-THIONE Allen R. Siedle Inorganic Chemistry Section, National Bureau of Standards Washington, D.C. 20234 (Received6December]974) We wish to report the preparation of complexes of 1,3dithiolene-2-thione,
~, which relate to the coordination chemistry of this
polyfunctional ligand.
In principle, ~ may bind to transition metals
through the thioketone sulfur and/or the endocyclic sulfur or form + complexes,
since the C3H3S 2
ring is isoelectronic with C6H 6.
syntheses proceed by displacement of a chelating diolefin
The
from
(diolefin)M(CO) 4 (M = Cr, MO) to afford products having a greater number of carbonyl groups than the starting complex. Treatment of bicyclo[2.2.1]heptadiene molybdenum tetracarbonyl with two equivalents of 1,3-dithiolene-2-thione
(i) in hot benzene produced
orange, crystalline 1,3-dithiolene-2-thione molybdenum pentacarbonyl (17% based on Mo), black solids and unreacted ~. achieved by elemental analysis singlet at 6C6D6 5.53.
was
(cyclohexane solution)
1955(vs) and 2070(w) cm.
band spectral pattern of carbonyl modes symmetry.
Characterization of ~
(2) and the IH NMR spectrum which showed a
The infrared spectrum
contained bands at 1935(s),
, ~,
-i
, exhibiting the three
(2A 1 + E) characteristic of C4v
The observed carbonyl frequencies are very similar to those in
(CH3CN)Mo(CO) 5, 1931(s),
1948(vs)
and 2085(w)
cm.
-I
(3).
Decomposition of
2a occurred on heating and a satisfactory mass spectrum could not be obtained. Red 1,3-dithiolene-2-thione chromium pentacarbonyl
(2), ~ ,
m.p. 96-98 ° , was similarly obtained from bicyclo[2.2.1]heptadiene chromium tetracarbonyl and ~. at 1933(s),
Metal carbonyl absorptions in this compound occurred
1950(vs), and 2060(w)
cm. -i 345
The 1 H NMR spectrum contained a
GroupVIbMetalCarbonylComplexes
346
singlet at 65.53.
Vol. 11,No. 5.
The mass spectrum contained a parent ion peak at m/e 326
and the 13C{1H} spectrum (C6D6) showed resonances at 223.0 (C=S), 216.8 (trans CO) and 215.3 ppm (cis CO) relative to (CH3)4Si in a 1:1:4 ratio. Compound &
is monomeric in benzene. The observation of only one resonance in the
&,Q
1 H NMR spectra of
indicates that the M(COj5 moiety is symmetrically bound to the ligand
through the exocyclic thioketone sulfur.
The 'H NMR spectrum of uncomplexed
,& in C6D6 consists of a singlet at 6 5.67.
The small upfield shift on
coordination, 0.14 ppm, suggests that the olefinic carbon-carbon bond in the ligand is not extensively involved in bonding interactions with the M(C0) 5 group, consistent with the infrared data, and indicates that these complexes are more closely represented by 2 than by the dipolar form 2. S
0
S
S
1
3
2a, M = MO 2b, M = Cr Details of the mechanism of formation of &,Q
are unclear.
It
is possible that an intermediate such as (C3H2S3)M(C0j4 abstracts a carbonyl group from (C7H8)M(C0)4 at a rate faster than which it reacts with additional &.
Other examples of carbonyl transfer reactions have been reported (4,5),
providing precedent for an abstraction step. it was observed that the yields of &,k
In support of this suggestion,
increased by a factor of three when
the reactions were run under an atmosphere of carbon monoxide. ACKXWLEDGEMENT The l3C NMR spectrum was obtained at the Laboratory of Chemistry, National Heart and Lung Institute.
The author is grateful for the
award of a NAS-NRC postdoctoral fellowship. REFERENCES 1.
L. R. Melby, H. D. Hartzler and W. A. Sheppard, J. Org. Chem., 9, 2456 (1974).
Vol. 11, No. 5.
Group Vlb Metal Carbonyl Complexes
347
2.
Anal.: Calcd. for C8H2MoO5S3: C, 25.95; H, 0.54; Mo, 25.95. Found: C, 25.59; H, 0.35; Mo, 25.88. Calcd. for C8H2CrO5S3: C, 29.45; H, 0.61; Cr, 15.95; S, 29.45; mol. wt. 326. Found: C, 29.24; H, 0.59; Cr, 16.21; S, 29.68; mol. wt. (osmometric in C6H6), 314.
3.
G. R. Dobson, M. F. Elsayed, I. W. Stolz and R. K. Sheline, Inorg. Chem., i, 526 (1962).
4.
B. L. Booth, M. J. Else, R. Fields and R. N. Hazeldine, J. Organometal. chem., 14, 417 (1968).
5.
J. J. Alexander and A. Wojcicki,
Inorg. Chem., 12, 74 (1973).
NUCL.
CHEM.
LETTERS
Vol.
11,
pp.
345-347,
1975.
Pergamon
Press.
Printed
in
Great
Britain.
GROUP VIb METAL CARBONYL COMPLEXES OF 1,3-DITHIOLENE-2-THIONE Allen R. Siedle Inorganic Chemistry Section, National Bureau of Standards Washington, D.C. 20234 (Received6December]974) We wish to report the preparation of complexes of 1,3dithiolene-2-thione,
~, which relate to the coordination chemistry of this
polyfunctional ligand.
In principle, ~ may bind to transition metals
through the thioketone sulfur and/or the endocyclic sulfur or form + complexes,
since the C3H3S 2
ring is isoelectronic with C6H 6.
syntheses proceed by displacement of a chelating diolefin
The
from
(diolefin)M(CO) 4 (M = Cr, MO) to afford products having a greater number of carbonyl groups than the starting complex. Treatment of bicyclo[2.2.1]heptadiene molybdenum tetracarbonyl with two equivalents of 1,3-dithiolene-2-thione
(i) in hot benzene produced
orange, crystalline 1,3-dithiolene-2-thione molybdenum pentacarbonyl (17% based on Mo), black solids and unreacted ~. achieved by elemental analysis singlet at 6C6D6 5.53.
was
(cyclohexane solution)
1955(vs) and 2070(w) cm.
band spectral pattern of carbonyl modes symmetry.
Characterization of ~
(2) and the IH NMR spectrum which showed a
The infrared spectrum
contained bands at 1935(s),
, ~,
-i
, exhibiting the three
(2A 1 + E) characteristic of C4v
The observed carbonyl frequencies are very similar to those in
(CH3CN)Mo(CO) 5, 1931(s),
1948(vs)
and 2085(w)
cm.
-I
(3).
Decomposition of
2a occurred on heating and a satisfactory mass spectrum could not be obtained. Red 1,3-dithiolene-2-thione chromium pentacarbonyl
(2), ~ ,
m.p. 96-98 ° , was similarly obtained from bicyclo[2.2.1]heptadiene chromium tetracarbonyl and ~. at 1933(s),
Metal carbonyl absorptions in this compound occurred
1950(vs), and 2060(w)
cm. -i 345
The 1 H NMR spectrum contained a
GroupVIbMetalCarbonylComplexes
346
singlet at 65.53.
Vol. 11,No. 5.
The mass spectrum contained a parent ion peak at m/e 326
and the 13C{1H} spectrum (C6D6) showed resonances at 223.0 (C=S), 216.8 (trans CO) and 215.3 ppm (cis CO) relative to (CH3)4Si in a 1:1:4 ratio. Compound &
is monomeric in benzene. The observation of only one resonance in the
&,Q
1 H NMR spectra of
indicates that the M(COj5 moiety is symmetrically bound to the ligand
through the exocyclic thioketone sulfur.
The 'H NMR spectrum of uncomplexed
,& in C6D6 consists of a singlet at 6 5.67.
The small upfield shift on
coordination, 0.14 ppm, suggests that the olefinic carbon-carbon bond in the ligand is not extensively involved in bonding interactions with the M(C0) 5 group, consistent with the infrared data, and indicates that these complexes are more closely represented by 2 than by the dipolar form 2. S
0
S
S
1
3
2a, M = MO 2b, M = Cr Details of the mechanism of formation of &,Q
are unclear.
It
is possible that an intermediate such as (C3H2S3)M(C0j4 abstracts a carbonyl group from (C7H8)M(C0)4 at a rate faster than which it reacts with additional &.
Other examples of carbonyl transfer reactions have been reported (4,5),
providing precedent for an abstraction step. it was observed that the yields of &,k
In support of this suggestion,
increased by a factor of three when
the reactions were run under an atmosphere of carbon monoxide. ACKXWLEDGEMENT The l3C NMR spectrum was obtained at the Laboratory of Chemistry, National Heart and Lung Institute.
The author is grateful for the
award of a NAS-NRC postdoctoral fellowship. REFERENCES 1.
L. R. Melby, H. D. Hartzler and W. A. Sheppard, J. Org. Chem., 9, 2456 (1974).
Vol. 11, No. 5.
Group Vlb Metal Carbonyl Complexes
347
2.
Anal.: Calcd. for C8H2MoO5S3: C, 25.95; H, 0.54; Mo, 25.95. Found: C, 25.59; H, 0.35; Mo, 25.88. Calcd. for C8H2CrO5S3: C, 29.45; H, 0.61; Cr, 15.95; S, 29.45; mol. wt. 326. Found: C, 29.24; H, 0.59; Cr, 16.21; S, 29.68; mol. wt. (osmometric in C6H6), 314.
3.
G. R. Dobson, M. F. Elsayed, I. W. Stolz and R. K. Sheline, Inorg. Chem., i, 526 (1962).
4.
B. L. Booth, M. J. Else, R. Fields and R. N. Hazeldine, J. Organometal. chem., 14, 417 (1968).
5.
J. J. Alexander and A. Wojcicki,
Inorg. Chem., 12, 74 (1973).