Convenient syntheses of [IrCl(CS)(PPh3)2] and a Bis(thiocarbonyl) complex of iridium

Article abstract of DOI:10.1021/om960205+

Treating [IrCl(CO)(PPh₃)₂] with ClC(=S)OR (R = C₆H₄Me-4) provides [IrCl₂{C(=S)OR}-(CO)(PPh₃)₂], which reacts with NaBH₄ to give [IrHCl{C(=S)OR}(CO)(PPh₃)₂]. The aryloxide group is cleaved by HCl to give [IrHCl₂(CS)(PPh₃)₂], which is dehydrochlorinated by DBU to provide [IrCl(CS)(PPh₃)₂] (overall yield for Ir(CO) → Ir(CS) 75%). Treating [IrCl(CS)-(PPH₃)₂] with ClC(=S)SPh provides [IrCl₂{C(=S)SPh}(CS)(PPH₃)₂] (in equilibrium with [IrCl-(η²-SCSPh)(CS)(PPH₃)₂]Cl) which reacts subsequently with I₂ or ICl to provide [IrCl₂(CS)₂-(PPH₃)²]X (X = I₃, Cl). [Ir(CS₂Ph)Cl₂(CO)(PPH₃)₂], however, reacts with I₂ to provide [IrClI₂(CS)(PPH₃)₂]. Reaction of [IrHCl₂(CS)(PPH₃)₂] with CNC₆H₃Me₂-2,6 does not proceed via migratory insertion but, rather, leads to reduction of iridium and formation of the salt [Ir(CNC₆H₃Me₂-2,6)₂(CS)(PPH ₃)₂]Cl. ^? Dedicated to Professor Max Herberhold on the occasion of his 60th birthday.

Full text of DOI:10.1021/om960205+

Organometallics 1996, 15, 3791-3797
3791
Articles
Con ven ien t Syn th eses of [Ir Cl(CS)(P P h 3)2] a n d a
Bis(th ioca r bon yl) Com p lex of Ir id iu m †
Anthony F. Hill*,‡ and J ames D. E. T. Wilton-Ely
Department of Chemistry, Imperial College of Science, Technology and Medicine,
London SW7 2AY, U.K.
Received March 19, 1996X
Treating [IrCl(CO)(PPh3)2] with ClC(dS)OR (R ) C6H4Me-4) provides [IrCl2{C(dS)OR}-
(CO)(PPh3)2], which reacts with NaBH4 to give [IrHCl{C(dS)OR}(CO)(PPh3)2]. The aryloxide
group is cleaved by HCl to give [IrHCl2(CS)(PPh3)2], which is dehydrochlorinated by DBU
to provide [IrCl(CS)(PPh3)2] (overall yield for “Ir(CO)” f “Ir(CS)” 75%). Treating [IrCl(CS)-
(PPh3)2] with ClC(dS)SPh provides [IrCl2{C(dS)SPh}(CS)(PPh3)2] (in equilibrium with [IrCl-
(η2-SCSPh)(CS)(PPh3)2]Cl) which reacts subsequently with I2 or ICl to provide [IrCl2(CS)2-
(PPh3)2]X (X ) I3, Cl). [Ir(CS2Ph)Cl2(CO)(PPh3)2], however, reacts with I2 to provide
[IrClI2(CS)(PPh3)2]. Reaction of [IrHCl2(CS)(PPh3)2] with CNC6H3Me2-2,6 does not proceed
via migratory insertion but, rather, leads to reduction of iridium and formation of the salt
[Ir(CNC6H3Me2-2,6)2(CS)(PPh3)2]Cl.
Sch em e 1
In tr od u ction
Wilkinson's archetypal thiocarbonyl complex [RhCl-
(CS)(PPh3)2] is conveniently obtained in good yield (ca.
80%) by treating [RhCl(PPh3)3] with CS2 and PPh3
(reaction 1).1 The preparation of the iridium analogue
PPh3
[RhCl(PPh3)3] + CS2
8
trans-[RhCl(CS)(PPh3)2] + SPPh3 + ... (1)
[IrCl(CS)(PPh3)2] (1b)2 is somewhat more problematical.
Two routes for the conversion of [IrCl(CO)(PPh3)2] (1a )
to its thiocarbonyl analogue are currently available,
each with their own attendant problems. The first
(Scheme 1),3 requiring anaerobic conditions, involves the
initial conversion of Vaska’s complex to [IrCl(N2)(PPh3)2]
using an organic azide followed by treatment with
carbon disulfide to provide an ill-defined metallacyclic
species. This is then converted to (1b) by phosphine
(overall yield 48%). The second route (Scheme 2)4 offers
the advantages of air-stable intermediates. Alkylation
of “IrCl(CS2)(CO)(PPh3)2” (generated in situ in CS2) with
methyl triflate to provide [IrCl{η2-SCSMe)(CO)-
(PPh3)2](O3SCF3) followed by triflate/hydride metathesis
gives [IrHCl{C(dS)SMe}(CO)(PPh3)2]. Thermolysis then
leads to elimination of methanethiol and carbon mon-
oxide and formation of 1b.
Sch em e 2
† Dedicated to Professor Max Herberhold on the occasion of his 60th
birthday.
‡ Email: a.hill@ic.ac.uk.
X Abstract published in Advance ACS Abstracts, August 1, 1996.
(1) Baird, M. C.; Wilkinson, G. J . Chem. Soc., Chem. Commun. 1966,
267.
(2) Yagupsky, M. P.; Wilkinson, G. J . Chem. Soc., A 1968, 2813.
(3) Kubota, M. Inorg. Synth. 1979, 19, 206. Kubota, M.; Carey, C.
R. J . Organomet. Chem. 1970, 24, 491.
(4) Collins, T. J .; Roper, W. R.; Town, K. G. J . Organomet. Chem.
1976, 121, C41.
We were eager to investigate further the chemistry
of [IrCl(CS)(PPh3)2] but were somewhat discouraged by
S0276-7333(96)00205-1 CCC: $12.00 © 1996 American Chemical Society

3792 Organometallics, Vol. 15, No. 18, 1996
Hill and Wilton-Ely
Sch em e 3
Sch em e 4. Rota tion a l Isom er ism in
Alk oxyth ioca r bon yl Com p lexes
Sch em e 5
of such a process would be rotational isomerism about
either the Ir-C or C-O bonds of the (aryloxy)thiocar-
bonyl ligand (Scheme 4). Both of these linkages can be
expected to have a degree of multiple bonding, albeit
small. Such rotational isomerism is a feature of related
alkoxycarbene complexes.
the associated problems with each of these approaches.
We have therefore developed an alternative procedure,
the advantages of which include (i) high overall yield,
(ii) short process times, (iii) reagents which are all
commercially available and cheap and have minimal
health and safety criteria, (iv) intermediates that are
all air-stable, and (v) the fact that the approach allows
the introduction of a second thiocarbonyl ligand to give
the first group 9 bis(thiocarbonyl) complex.
The two chloride ligands of 2 show different chemical
reactivities. Treating 2 with an excess of ethanolic
sodium borohydride leads to replacement of only one
chloride and formation of [IrHCl{C(dS)OR}(CO)(PPh3)2]
(3). It is most likely that it is the chloride trans to the
(aryloxy)thiocarbonyl ligand which is replaced, on the
basis of chemical intuition (σ-organyls having a stronger
trans effect than carbonyl ligands) and spectroscopic
data for 3. Most spectroscopic data for 3 are comparable
to those for 2 and need no further discussion. Those
associated with the hydride and (aryloxy)thiocarbonyl
ligand are, however, noteworthy. First, the hydride
Resu lts a n d Discu ssion
The chemistry described employs chlorothionoformate
esters, ClC(dS)OAr (Ar ) C6H5, C6H4Me-4), as source
molecules for the thiocarbonyl ligand. The processes
proceed equally well for both aryl substituents; however,
those based on the 4-tolyl derivatives will be discussed,
due to the spectroscopic advantages (1H and 13C NMR,
IR). Treating 1a with ClC(dS)OC6H4Me-4 (hereafter
R ) C6H4Me-4) in tetrahydrofuran provides the yellow
complex [IrCl2{C(dS)OR}(CO)(PPh3)2] (2) in 95% yield.
The identity of this complex follows unambiguously from
spectroscopic data. The occurrence of an oxidative-
addition process is indicated by the high-frequency shift
in the ν(CO) IR absorption to 2074 and 2054 cm-1
(Nujol) (1961 cm-1 in the precursor). The stereochem-
istry at iridium (Scheme 3) follows from the appearance
of two ν(IrCl2) absorptions at 317 and 271 cm-1, a singlet
resonance in the 31P NMR spectrum (δ -16.1 ppm), and
a triplet carbonyl resonance in the 13C NMR spectrum
(δ 156.4 ppm; J (P2C) ) 7.2 Hz ). The resonance derived
from the (aryloxy)thiocarbonyl carbon appears to lower
field, at δ 215.4 ppm, also as a triplet (J (P2C) ) 5.4 Hz)
and those due to the phosphine aryl groups appear as
virtual triplets, further confirming the trans bis(phos-
phine) arrangement. In addition to confirming the gross
molecular composition (M+ at m/ z 967) and revealing
a range of ligand fragmentations, the FAB-mass spec-
trum also shows a peak due to “[M - OR]+”, which bodes
well for the subsequent chemistry.
1
ligand gives rise to a triplet resonance in the H NMR
spectrum at δ -11.0 (J (PH) ) 14.5 Hz). Second,
although the 13C NMR resonance associated with the
carbonyl ligand shows only a small shift to δ 161.8 ppm
(J (P2C) ) 8.1 Hz), that due to the (aryloxy)thiocarbonyl
shows a dramatic shift to lower field to 268.5 ppm and
is observed as two overlapping triplets. This presum-
ably results from the coupling to the trans hydride being
comparable to the cis PC coupling (ca. 7 Hz). The large
shift may be due to the increase in carbene character
which would be favored by a stronger trans donor ligand
(Scheme 5). This is also supported by the apparent
absence of rotational isomerism about the C-O bond
of this ligand, which should have reduced multiple-bond
character.
The aryloxide group of 3 is readily cleaved by Brøn-
stead acids. Treating 3 with HCl leads to loss of both
cresol and carbon monoxide to provide [IrHCl2(CS)-
(PPh3)2] (4) in high yield. The stereochemistry at
iridium (Scheme 3) follows from the appearance of two
ν(IrCl2) absorbances in the infrared spectrum (CsI) at
293 and 261 cm-1 and a singlet resonance in the 31P-
{1H} NMR spectrum (δ 1.86 ppm). The thiocarbonyl
ligand which results from the aryloxide abstraction
gives rise to an intense IR absorption at 1358 cm-1. The
complex (4) is readily dehydrochlorinated by 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) in a mixture of
dichloromethane and ethanol (25 °C) to provide [IrCl-
(CS)(PPh3)2] (1b), characterized by comparison of spec-
The splitting of the ν(CO)-associated absorption in the
infrared spectrum (retained in solution) suggests the
possibility of isomers which nevertheless interconvert
within the NMR time scale. The most plausible origin

Thiocarbonyl Complexes of Iridium
Organometallics, Vol. 15, No. 18, 1996 3793
a
Ta ble 1. In fr a r ed Da ta (cm -1
)
for th e Com p lexes
Sch em e 6
[MClX(CS2R)(AB)L2] a n d [MX(η2-SCSR)(AB)L2]+
(MX(AB) ) OsI (NO),b OsCl (NO),b Ir Cl (CO), Ir Cl
(CS); L ) P P h 3)
complex
ν(AB) ∆ν(AB) ν(CS2) ∆ν(CS2)
[OsClI(CS2Me)(NO)L2]
1843
1798
991
1122
1128
[OsI(η2-SCSMe)(NO)L2]+
-45
-51
+131
+137
[OsCl(η2-SCSMe)(NO)L2]+ 1792
[IrCl2(CS2Ph)(CO)L2]
2069
2028
1009
1136
[IrCl(η2-SCSPh)(CO)L2]+
-41
-3
+137
+95
[IrCl2(CS2Ph)(CS)L2]
1363
1360
1029
1124
[IrCl(η2-SCSPh)(CS)L2]+
a
b
Data from Nujol mulls. From ref 9.
triplets (IrCS, δ 244.9 ppm, J (PC) ) 8.0 Hz; OCS, δ
218.3 ppm, J (PC) ) 5.4 Hz). The FAB mass spectrum
of 5 differs slightly from that of 2 in that while the base
peak for 2 corresponded to loss of chloride, such a
fragmentation for 5 is not as strongly observed. Rather,
the base peak is due to the molecular ion, with only
minor peaks being observed for loss of phosphine (42%)
followed by loss of chloride (12%). Presumably this
reflects the more electron poor iridium center in 5
relative to 2, which reduces the facility of iridium-
halide ionization.
troscopic data with those previously reported.3,4 The
multistep sequence for the conversion of 1a to 1b may
be performed without isolation of the intermediates (see
Experimental Section), giving yields in excess of 75%
for the IrCO f IrCS conversion.
Reaction of 1a with ClCS2Ph provides [IrCl(η2-SCSPh)-
(CO)(PPh3)2]Cl (6‚Cl) or [IrCl2(CS2Ph)(CO)(PPh3)2] (7),
depending on the solvent combination used for recrys-
tallization. From weakly polar or nonpolar solvent
mixtures the isolated species is the neutral complex
[IrCl2(CS2Ph)(CO)(PPh3)2] (7; monodentate (phenylthio)-
thiocarbonyl ligand), as indicated by the appearance of
Bis(th ioca r bon yl) Com p lexes. With access to 1b
we have extended the approach to the preparation of
bis(thiocarbonyl) complexes. This class of complex
remains rare,5 due to the difficulties in the construction
of the thiocarbonyl ligand within a coordination sphere.
The three successful approaches previously employed
involve the following. (i) Successive carbonyl photolabi-
lization has been used to generate solvent-stabilized
species which react with CS2 and phosphine. This has
been extended to a tris(thiocarbonyl) complex of man-
ganese, albeit in low overall yield.6 (ii) Reduction of
[OsCl2(CS)(PPh3)3] to [Os(CO)(CS)(PPh3)3] occurs via a
multistep procedure, followed by coordination of CS2 to
provide [Os(η2-SCS)(CO)(CS)(PPh3)2]. Alkylation of the
coordinated CS2 ligand followed by thiol protonolysis
with hydrohalic acids provides [OsX2(CS)2(PPh3)2] (X )
Cl, Br).7 (iii) Reaction of [OsCl2()CCl2)(CS)(PPh3)2]
with sodium hydrosulfide provides [OsCl2(CS)2(PPh3)2].
This last approach has also been extended to the mixed-
chalcogenocarbonyl complex [OsCl2(CS)(CSe)(PPh3)2].8
The reaction of 1b with ClC(dS)OR proceeds in a
manner completely analogous to that of 1a to provide
[IrCl2{C(dS)OR}(CS)(PPh3)2] (5) (Scheme 6). Oxidation
of the iridium(I) center is accompanied by a bathochro-
mic shift in the thiocarbonyl infrared absorption (Nujol,
1365 cm-1; CH2Cl2, 1369 cm-1). Once again, bands are
observed at 1113 and 999 cm-1 (cf. 1119 and 1008 for
2) due to ν(CsO) and ν(CdS) vibrations of the (aryloxy)-
thiocarbonyl ligand. Both thiocarbonyl carbon nuclei
are observed to low field in the 13C NMR spectrum as
bands at 1009 s and 910 m cm-1
absorption occurs at 2069 cm-1 The salt [IrCl(η2-
.
The carbonyl
.
SCSPh)(CO)(PPh3)2]Cl (6‚Cl) has a ν(C-S) absorption
at 1136 cm-1. If the product is, however, crystallized
from polar solvents, e.g., a mixture of dichloromethane
and ethanol, the salt [IrCl(η2-SCSPh)(CO)(PPh3)2]Cl
(6‚Cl) is obtained; alternatively, metathesis with NH4-
PF6 provides exclusively [IrCl(η2-SCSPh)(CO)(PPh3)2]-
PF6 (6‚PF6). We have encountered similar behavior in
the formally isoelectronic osmium compounds [OsI(η2-
SCSMe)(NO)(PPh3)2]Cl and [OsClI(CS2Me)(NO)(PPh3)2].9
Notably, the conversion of a neutral nitrosyl or carbonyl
complex to a cationic derivative is normally expected
to result in a shift to higher frequency of ν(NO) or ν-
(CO); however, in both systems the ionization of the
complexes and the adoption of η2-SCSR coordination
results in a decrease in ν(NO) and ν(CO). Table 1
summarizes the changes in infrared data for these two
pairs of complexes in addition to the thiocarbonyl
analogues of 6+ and 7, which show interconversion
between the two forms (vide infra). These data indicate
that the bidentate mode of (alkylthio)thiocarbonyl co-
ordination results in a substantial transfer of electron
density to the metal center relative to monodentate
coordination. Upon σ-coordination the CS2R ligand acts
as a strong π-acid; however, η2(SC) coordination renders
it a strong donor ligand. These effects are presumably
exaggerated by a stereochemistry at the metal center
in which the sulfur donor ligates trans to the π-acid.
Similar results are to be found for the analogous
(5) For a review of thiocarbonyl coordination chemistry see: Broad-
hurst, P. V. Polyhedron 1985, 4, 1801.
(6) Fenster, A. E.; Butler, I. S. Inorg. Chem. 1974, 13, 915.
(7) Collins, T. J .; Roper, W. R. J . Organomet. Chem. 1977, 139, C9.
(8) Clark, G. R.; Marsden, K.; Rickard, C. E. F.; Roper, W. R.; Wright,
L. J . J . Organomet. Chem. 1988, 338, 393.
(9) Herberhold, M.; Hill, A. F.; McAuley, N.; Roper, W. R. J .
Organomet. Chem. 1986, 310, 95.

3794 Organometallics, Vol. 15, No. 18, 1996
Hill and Wilton-Ely
Ta ble 2. 31P {1H} NMR Da ta a for Mon od en ta te a n d
Bid en ta te Com p lexes of P h en oxyth ioca r bon yl a n d
(P h en ylth io)th ioca r bon yl a n d Th ioca r ba m oylb
Liga n d s
(CO)(PPh3)2] reacts with iodine to provide the salt [IrCl2-
(CO)(CS)(PPh3)2]I3 and MeSI.11 A similar reaction
ensues between 8‚Cl/9 and iodine to provide green
[IrCl2(CS)2(PPh3)2]I3 (10‚I3). Our interest in the com-
plex 10+ stems from its anticipated reactivity toward
nucleophiles, and accordingly, the triiodide counteranion
was considered inappropriate. Attempts to metathesize
this with NH4PF6 in dichloromethane/ethanol mixtures
were unsuccessful, due to the reaction of ethanol with
one of the thiocarbonyl ligands to provide an as yet
uncharacterized compound. An alternative preparation
of 10+ was therefore investigated, using iodine monochlo-
ride as the source of electrophilic iodine but providing
the more “innocent” chloride counteranion. The reaction
of 8‚Cl/9 with ICl leads to clean formation of orange
[IrCl2(CS)2(PPh3)2]Cl (10‚Cl) in high yield, indicating
that the intense green color of the triiodide salt stems
from the counteranion and not the metal complex. The
stereochemistry at iridium is cis,cis,trans, as indicated
by the appearance of a singlet resonance in the 31P{1H}
NMR at δ -11.2 ppm for 10‚I3 (δ -11.0 ppm for 10‚Cl).
Two ν(IrCl2) absorptions are observed (320, 300 cm-1),
indicating the cis IrCl2 stereochemistry. Two ν(CS)-
associated infrared absorptions are observed (KBr disc,
1425, 1357; CH2Cl2, 1438, 1369 cm-1) to particularly
high frequency, indicating both the electron-poor nature
of the iridium center and the mutual cis disposition of
the two thiocarbonyl ligands. These values may be
compared with 1400 cm-1 for [IrCl2(CO)(CS)(PPh3)2]+ 11
and 1370 and 1260 cm-1 for [OsCl2(CS)2(PPh3)2].7,8 The
complexes are formally isoelectronic, and spectroscopic
data are comparable notwithstanding the perturbations
associated with the more electron poor iridium centers
(cationic Ir(III) vs neutral Os(II)). These changes are
reflected in an increase of approximately 0.82 N m-1 of
the thiocarbonyl Cotton-Kraihanzel force constants
from 7.00 N m-1 for the osmium complex to 7.82 N m-1
for the iridium salt. Finally, the low-field region of the
13C{1H} NMR spectrum shows a triplet resonance at
232.4 ppm with a reduced coupling to phosphorus (J (PC)
) 5.4 Hz) relative to that in, e.g., 4.
The facile cleavage of ISMe from [IrCl2(CS2Me)(CO)-
(PPh3)2] by iodine to provide [IrCl2(CO)(CS)(PPh3)2]+
suggested that 7 should also serve as a precursor for
this cationic complex. This proved not to be the case.
Reaction of 7 with iodine provided the neutral iridium-
(III) thiocarbonyl complex [IrClI2(CS)(PPh3)2]. The
reasons for the different outcomes for the two iodination
reactions remain obscure.
P r ep a r a tion of [Ir (CNC6H3Me2-2,6)2(CS)(P P h 3)2]-
Cl. One exciting aspect of thiocarbonyl chemistry to
emerge in recent times is the tendency of this ligand to
enter into migratory insertion reactions, even involving
ligands with such negligible migratory aptitude as
hydrides12 and σ-silyls.13 The complex 4, with both a
hydride and a thiocarbonyl ligand, might appear to be
a suitable precursor for thioformyl complexes. Treating
4 with isonitriles might be expected to trap such a
species, should it be in tautomeric equilibrium with 4.
Reaction of 4, however, with excess CNC6H3Me2-2,6
complex
δ (ppm)
[IrCl2(CS2Ph)(CO)L2]
[IrCl2(CS2Ph)(CS)L2]
[IrCl2(CSOR)(CO)L2]
[IrCl2(CSOR)(CS)L2]
-17.3
-13.0c
-16.1
-9.6
[IrCl(η2-SCSPh)(CO)L2]+
[IrCl(η2-SCSPh)(CS)L2]+
[IrCl(η2-SCNMe2)(CO)L2]+
[IrCl(η2-SCNMe2)(CS)L2]+
-1.8
1.6
-2.4
-0.7
a
Data obtained from saturated solution in CDCl3 at 25 °C; R
b
c
) C6H4Me-4. Data from ref 10. In equilibrium with ca. 5% of
8‚Cl.
thiocarbamoyl complex [IrCl(η2-SCNMe2)(CO)(PPh3)2]+.10
In general the thiocarbamoyl ligand shows a greater
propensity for bidentate coordination, being a stronger
net donor than either the alkoxythiocarbonyl or (alky-
lthio)thiocarbonyl ligand.
A similar reaction of 1b with ClCS2Ph provides the
salt [IrCl(η2-SCSPh)(CS)(PPh3)2]Cl (8‚Cl), which is in
solvent-dependent equilibrium with [IrCl2(CS2Ph)(CS)-
(PPh3)2] (9). As with 6+ and 7 in nonpolar or weakly
polar solvents, e.g., tetrahydrofuran, the neutral species
9 predominates. However, in more polar solvents (e.g.,
dichloromethane-ethanol mixtures) ionization is fa-
vored, followed by bidentate coordination of the (alky-
lthio)thiocarbonyl ligand. This would appear to be in
contrast to the alkoxythiocarbonyl complexes described
above but is supported by the greater tendency of
thiocarbamoyl ligands to adopt bidentate coordination
modes. The bidentate mode of coordination appears to
be increasingly favored with increasing π-dative capac-
ity of the thiocarbonyl substituent. The salt [IrCl(η2-
SCNMe2)(CO)(PPh3)2]Cl shows no tendency toward
monodentate thiocarbamoyl coordination in the pres-
ence of excess halide.10 The compounds 8‚Cl and 9
provide similar FAB-mass spectra independent of the
solvent of crystallization suggesting preionization to 8‚-
Cl in the nba matrix. The base peaks for the spectra
correspond to the ion [IrCl(η2-SCSPh)(CS)(PPh3)2]+ (8+),
with minor fragmentations due to loss of ClSPh (8%)
and sequential loss of phosphine (24%) and chloride
(5%). The exclusive isolation of 8+ is achieved by Cl/
PF6 metathesis and fractional crystallization of [IrCl-
(η2-SCSPh)(CS)(PPh3)2]PF6 (8‚PF6). 31P{1H} NMR data
for the complexes 9 and 8+ also further confirm the
nature of the two isomers when compared with the
related complexes discussed above. These data are
summarized in Table 2 in addition to data for carbamoyl
analogues,10 and show that for all the neutral η1
examples of (aryloxy)thiocarbonyl and (arylthio)thio-
carbonyl complexes, a singlet resonance is observed in
the region δ -9.6 to -17.3 ppm. These data span a
wider range of values than for the bidentate isomers,
which give rise to peaks in the range δ +1.6 to -2.4
ppm.
The position of the ionization equilibrium does not
interfere with the next step on the way to a bis-
(thiocarbonyl) complex. Roper has previously described
the use of iodine to cleave a methylthio group (as ISMe)
from a (methylthio)thiocarbonyl ligand: [IrCl2(CS2Me)-
(11) Roper, W. R.; Town, K. G. J . Chem. Soc., Chem. Commun. 1977,
781.
(12) Collins, T. J .; Roper, W. R. J . Organomet. Chem. 1978, 159,
73.
(13) Rickard, C. E. F.; Roper, W. R.; Salter, D. M.; Wright, L. J .
Organometallics 1992, 11, 2323.
(10) Hill, A. F.; Wilton-Ely, J . D. E. T., manuscript in preparation.

Thiocarbonyl Complexes of Iridium
Organometallics, Vol. 15, No. 18, 1996 3795
821 (δ(C6H4)); in CH2Cl2, 2076, 2061 (ν(CO)); in CsI, 317, 271
(cis ν(IrCl2)). NMR (CDCl3, 25 °C): 1H δ 2.21 [s, 3 H, CH3],
5.68, 6.84 [(AB)2, 4 H, J (AB) ) 8.3 Hz, C6H4], 7.36, 8.01 [m ×
2, 20 H, PC6H5] ppm; 13C{1H} δ 215.4 [t, J (PC) ) 5.4 Hz,
IrCSO], 156.4 [t, J (PC) ) 7.2 Hz, IrCO], 153.9 [s, C1(OC6H4)],
134.9, 130.8, 128.8, 127.9 [vt × 4, C(3,5),4,(2,6)(PC6H5)], ca. 115.1
[s, C4(OC6H4)], 128.8 [s, C2,6(OC6H4)], 121.3 [s, C3,5(OC6H4)],
20.7 [s, CH3] ppm; 31P{1H}:, -16.1 ppm. FAB-MS: m/ z (%
abundance) [assignment] 967 (2.4) [M]+, 931 (100) [M - Cl]+,
903 (9) [M - Cl - CO]+, 859 (7) [M - OR]+, 796 (5) [M - CO
- Cl - OR]+, 751 (3) [M - Cl - CO - CSOR]+, 669 (5) [M -
Cl - PPh3]+, 641 (36) [M - Cl - CO - PPh3]+, 605 (12) [M -
Cl2 - CO - PPh3]+, 497 (21) [Ir(CS)(PPh3)]+, 453 (10) [Ir-
PPh3]+, 297 (61) [Ph3PHCl]+, 262 (32) [PPh3]. Anal. Found:
C, 54.8; H, 3.8. Calcd for C45H37Cl2IrO2P2S‚0.25CH2Cl2: C,
55.0; H, 3.8. The solvent of crystallization was confirmed by
NMR integration.
leads not to the thioformyl complex [IrCl2{C-
(dS)H}(CNC6H3Me2-2,6)(PPh3)2] but rather via reduc-
tive dehydrochlorination to the monovalent iridium salt
[Ir(CNC6H3Me2-2,6)2(CS)(PPh3)2]Cl (11‚Cl), which may
be metathesized with NH4[PF6] to give 11‚PF6. The
geometry about iridium does not follow unambiguously
from spectroscopic data, in that trigonal-bipyramidal
structures with either trans-axial or cis-equatorial iso-
cyanide ligands are plausible. The 31P{1H} NMR spec-
trum consists of a singlet (δ 7.53 ppm), while the 1H
NMR spectrum indicates that the four isonitrile methyl
groups are equivalent (δ 1.80 ppm). The infrared
spectrum shows three isonitrile bands both in the solid
state (Nujol: 2171, 2141, 2112 cm-1) and in solution
(CH2Cl2: 2176, 2136, 2108 cm-1), although there is only
one resolvable ν(CS)-associated absorption (Nujol: 1283
cm-1) in a region consistent with “CS” bound to monov-
alent cationic iridium. Two possibilities are considered.
First, there may be an intramolecular Berry pseudoro-
tation interconverting the two isomers, or second, the
complex may be in dissociative equilibrium with the
coordinatively unsaturated complex [Ir(CNC6H3Me2-
2,6)(CS)(PPh3)2]+, with either of these processes occur-
Syn th esis of [Ir HCl{C(dS)OC6H4Me-4}(CO)(P P h 3)2] (3).
A magnetically stirred solution of 2 (4.30 g, 4.45 mmol) in
tetrahydrofuran (100 cm3) and ethanol (100 cm3) was treated
with a filtered solution of sodium borohydride (0.40 g, 10.5
mmol) in ethanol (30 cm3). Stirring was continued for 60 min,
during which time a pale green-yellow solid crystallized. The
crystals were isolated by filtration, washed with ethanol (50
cm3), and petroleum ether (50 cm3) and dried in vacuo. The
product could be recrystallized from a mixture of dichlo-
romethane and ethanol; however, the crude material obtained
above was of sufficent purity for spectroscopic and preparative
purposes. Yield: 3.90 g (94%). IR (cm-1) Nujol, 2051, 1992
(νCO), 1276, 1259, 1130, 1001, 946, 880, 825 in CH2Cl2, 2039
(ν(CO)); in CsI, 310 (ν(IrCl)). NMR (CDCl3, 25 °C): 1H, δ -11.0
[t, 1 H, J (PC) ) 14.5 Hz, IrH], 2.22 [s, 3 H, CH3], 5.72, 6.89
[(AB)2, 4 H, J (AB) ) 8.3 Hz], 7.4, 7.7 [m × 2, 30 H, PC6H5]
ppm; 13C{1H}, δ 268.5 [dt, J (HC) ≈ J (PC) ≈ 7 Hz, IrCSO],
161.8 [t, J (PC) ) 8.1 Hz, IrCO], 155.6 [s, C1(OC6H4)], 134.8,
131.0, 130.5, 128.2 [vt × 4, C(3,5),4,(2,6)(PC6H5)], 134.4 [s, C4-
(OC6H4)], 129.0 [s, C2,6(OC6H4)], 122.2 [s, C3,5(OC6H4)], 20.9 [s,
CH3]; 31P{1H}, δ -2.20. FAB-MS: m/ z (% abundance) [as-
signment] 933 (24) [M]+, 897 (4) [M - Cl]+, 869 (3) [M - Cl -
CO]+, 825 (11) [M - HOR]+, 781 (42) [M - HCSOR]+, 745 (28)
[M - Cl - HCSOR]+, 635 (8) [M - Cl - PPh3]+, 483 [Ir(CO)-
(PPh3)]+, 263 (100) [HPPh3]+. Anal. Found: C, 56.2; H, 4.1.
Calcd for C45H38ClIrO2P2S‚0.5CH2Cl2: C, 56.1; H, 4.0. The
solvent of crystallization was confirmed by NMR integration.
Syn th esis of [Ir HCl2(CS)(P P h 3)2] (4). A solution of (3)
(0.20 g, 0.22 mmol) in dichloromethane (10 cm3) was treated
with concentrated hydrochloric acid (1 cm3). Ethanol (20 cm3)
was then added, and the total solvent volume was reduced to
ca. 10 cm3. The colorless microcrystals which formed were
isolated by filtration, washed with ethanol (2 × 10 cm3) and
light petroleum ether (2 × 10 cm3), and dried in vacuo. The
complex was recrystallized from a mixture of dichloromethane
and ethanol. Yield: 0.15 g (84%). A larger scale run (3.80 g)
resulted in an improved yield [3.25 g (96%)]. IR (cm-1): Nujol,
2022 (ν(IrH)), 1358 (ν(CS)); in CsI 1357 (ν(CS)), 293, 261 (cis-
IrCl2). NMR (CDCl3, 25 °C):1H, δ -13.9 [t, 1 H, J (PH) ) 11.2
Hz, IrH], 7.39, 7.82 [m × 2, 30 H, PC6H5]; 13C{1H}, insuf-
ficiently soluble in CDCl3, (CD3)2CO, or CD2Cl2; 31P{1H}, δ 1.86.
FAB-MS: useful data not obtained. Anal. Found: C, 51.7;
H, 3.6. Calcd for C37H31Cl2IrP2S‚0.25CH2Cl2: C, 51.5; H, 3.7.
1
ring within the 31P and H NMR time scales. The peaks
in the aryl region of the 13C{1H} NMR spectrum are
somewhat broad; however, a virtual triplet due to the
ipso carbon nuclei of the phosphine ligands is apparent,
suggesting that the the trans-bis(phosphine) geometry
is adopted. The salt 11‚Cl is also obtained from the
reaction of preformed and isolated 1b with excess
CNC6H3Me2-2,6; thus, it is not clear whether in the
transformation 4 f 11‚Cl reversible dehydrochlorina-
tion occurs prior to isonitrile coordination or if inter-
mediates of the form [IrHCl(CNC6H3Me2-2,6)(CS)(PPh3)2]-
Cl are involved.
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless otherwise indicated, all
manipulations were carried out under aerobic conditions using
solvents and reagents as received from commercial sources.
Vaska’s complex [IrCl(CO)(PPh3)2] was prepared according to
the method outlined in ref 14, with the exception that
hexachloroiridic acid was used in place of iridium(III) chloride
with no substantial compromise in yield. 1H, 13C{1H} and 31P-
{1H} NMR spectra were recorded on a J EOL J NM EX270
NMR spectrometer and calibrated against internal Me4Si (1H),
internal CDCl3 (13C), or external H3PO4 (31P). Infrared spectra
were recorded using a Perkin-Elmer 1720-X FT-IR spectrom-
eter. Characteristic absorptions due to coordinated triph-
enylphosphine are omitted from the data below. FAB mass
spectrometry was carried out using an Autospec Q mass
spectrometer employing nitrobenzyl alcohol as matrix. Abun-
dances are given for the major peak of isotopic envelopes
confirmed by simulation. For salts, “M” refers to the cationic
complex. Elemental microanalytical data were obtained from
the ICSTM microanalytical service.
Syn th esis of [Ir Cl2{C(dS)OC6H4Me-4}(CO)(P P h 3)2] (2).
A suspension of [IrCl(CO)(PPh3)2] (3.70 g, 4.75 mmol) and
ClC(dS)OC6H4Me-4 (0.80 cm3, 0.98 g, 5.3 mmol) in tetrahy-
drofuran (10 cm3) was stirred for 1 h, and then ethanol (20
cm3) was added. Concentration under reduced pressure
provided yellow crystals, which were isolated by filtration and
washed with light petroleum ether. The complex is mildly
light sensitive as a solid. Yield: 4.35 g (95%). IR (cm-1) in
Nujol, 2074, 2054 (ν(CO)), 1119, 1008 (ν(COC) and ν(CdS)),
Syn th esis of [Ir Cl(CS)(P P h 3)2] (1b). (a ) F r om 4.
A
solution of 4 (0.90 g, 1.1 mmol) in dichloromethane (50 cm3)
and ethanol (20 cm3) was treated with DBU (0.5 cm3). The
mixture was stirred for 1 h, during which time bright orange
crystals formed. The suspension was concentrated under
reduced pressure to ca. 30 cm3, and the orange microcrystals
were isolated by filtration, washed with ethanol (2 × 10 cm3)
and light petroleum ether (10 cm3), and dried in vacuo.
Yield: 0.67 g (78%).
(b) F r om 1a . A suspension of 1a (4.00 g, 5.13 mmol) in
tetrahydrofuran (100 cm3) was treated with ClC(dS)OC6H4-
Me-4 (1.2 cm3, 1.43 g, 7.67 mmol) and the mixture stirred for
(14) Vrieze, K.; Collman, J . P.; Sears, C. T., J r.; Kubota, M. Inorg.
Synth. 1968, 11, 101.

3796 Organometallics, Vol. 15, No. 18, 1996
Hill and Wilton-Ely
1 h. Ethanol (100 cm3) was then added, followed by a filtered
solution of sodium borohydride (0.50 g, 13 mmol, excess) in
ethanol (50 cm3), and the mixture was stirred for 60 min. The
solvent was then removed under reduced pressure, the residue
was extracted with dichloromethane, and the combined ex-
tracts were filtered through diatomaceous earth. To the
resulting filtrate was added concentrated hydrochloric acid (ca.
5 cm3), and the mixture was stirred for 20 min or until the
solution was colorless. Ethanol (100 cm3) was then added, the
total solvent volume was reduced to ca. 80 cm3, and the
supernatant was decanted from the colorless precipitate. The
precipitate was washed by decantation with ethanol (3 × 20
cm3) and then suspended in dichloromethane (100 cm3) and
treated with DBU (4.0 cm3, 3.93 g, 25.8 mmol) and stirred until
all of the white solid had dissolved to give a bright orange
solution (ca. 60 min). This solution was then diluted with
ethanol and concentrated under reduced pressure to provide
orange crystals of 1b, which were washed with ethanol (4 ×
20 cm3) and light petroleum ether (20 cm3) and dried in vacuo.
Yield: 3.00 g (75% based on 1a ). IR and elemental microana-
lytical data for 1b are comparable to those previously re-
ported.3 NMR (CDCl3, 25 °C): 31P{1H} δ 8.0 ppm. FAB-MS:
m/ z (% abundance) [assignment] 796 (47) [M]+.
Syn th esis of [Ir Cl2{C(dS)OC6H4Me-4}(CS)(P P h 3)2] (5).
A suspension of [IrCl(CS)(PPh3)2] (0.28 g, 0.35 mmol) and
ClC(dS)OC6H4Me-4 (0.06 cm3, 0.07 g, 0.39 mmol) in tetrahy-
drofuran (10 cm3) was stirred for 30 min, and then ethanol
(30 cm3) was added, followed by hexane (20 cm3). Concentra-
tion under reduced pressure provided a precipitate of the crude
material, which was crystallized from a mixture of dichlo-
romethane and hexane. The compound is mildly light sensi-
tive as a solid and is not amenable to chromatography.
Yield: 0.25 g (72%). IR (cm-1): in Nujol, 1365 (ν(CS)), 1113,
999 (ν(COC) and ν(CdS)), 820 (δ(C6H4)); inCH2Cl2, 1369 (ν-
(CS)). NMR (CDCl3, 25 °C): 1H, δ 2.24 [s, 3 H, CH3], 5.90,
6.92 [(AB)2, 4 H, J (AB) ) 8.4 Hz, C6H4], 7.34, 8.02 [m × 2, 20
H, PC6H5]; 13C{1H}, δ 244.9 [t, J (PC) ) 8.0 Hz, IrCS], 218.3
[t, J (PC) ) 5.4 Hz, IrCSO], 154.3 [s, C1(OC6H4)], 135.6, 130.7,
127.6 [vt × 3, C(3,5),4,(2,6)(PC6H5)], 129.6 [vt + s, C1(PC6H5) and
C3,5(OC6H4)], 115.2 [s, C4(OC6H4)], 20.8 [s, CH3]; 31P{1H}, δ
-9.64. FAB-MS: m/ z (% abundance) [assignment] 947 (100)
[M - Cl]+, 685 (41) [M - PPh3]+, 649 (13) [M - HCl - PPh3]+,
262 [PPh3]+. Anal. Found: C, 54.7; H, 3.8. Calcd for
and ethanol (10 cm3) was treated with a solution of NH4[PF6]
(0.10 g, 0.61 mmol, excess) in water (1 cm3) and ethanol (30
cm3). Slow concentration of the mixture under reduced pres-
sure provides the salt 6‚PF6 in quantitative yield. IR (cm-1):
in Nujol, 2028 (ν(CO)), 1136 (ν(SCS)); in CH2Cl2, 2047 (ν(CO)).
NMR (CDCl3, 25 °C): 1H, δ 6.44 [d, 2 H, J (HH) ) 7.3 Hz, H2,6
-
(SC6H5)], 7.24-7.97 [m, 33 H, PC6H5 and H3-5(SC6H5)]; 13C-
{1H}, δ 238.6 [t, SCS, J (PC) ≈ 3.6 Hz], 168.8 [t, IrCO, J (PC)
) 8.9 Hz], 134.4-125.7 [C6H5]; 31P{1H} δ -1.77. FAB-MS:
m/ z (% abundance) [assignment] 933 (100) [M]+, 905 (3) [M
- CO]+, 780 (2) [M - CS2Ph]+, 643 (53) [M - CO - PPh3].
Anal. Found: C, 49.1; H, 3.1. Calcd for C44H35ClF6IrOP3S2:
C, 49.0; H, 3.3.
Syn th esis of [Ir Cl2(CS2P h )(CS)(P P h 3)2] (9). A suspen-
sion of 1b (0.20 g, 0.25 mmol) in benzene (10 cm3) was treated
with ClC(dS)SPh (0.03 cm3, 0.04 g, 0.28 mmol), resulting in
dissolution of 1b. The mixture was stirred for 60 min and then
freed of volatiles under reduced pressure. The residue was
then crystallized from a mixture of tetrahydrofuran and
cyclohexane to provide the desired complex 9. Yield: 0.22 g
(89%). IR (cm-1): in Nujol, 1363 (ν(CS)), 1029 (ν(SCS)). NMR
(CDCl3, 25 °C):1H, δ 6.35 [d, 2 H, J (HH) ) 7.1 Hz, H2,6(SC6H5)],
7.15, 7.24 [t × 2, 3 H, J (HH) ) 7.1 Hz, H3-5(SC6H5)], 7.30-
8.09 [m, 30 H, PC6H5]; 13C{1H}, δ 242.8 [t(br), IrCS, J (PC) ≈
7.1 Hz], 136.4 [s, C1(SC6H4)], 135.6, 130.6, 128.9 [vt(br) × 3,
C(3,5),4,1(PC6H5)], 133.7 [s, C3,5(SC6H4)], 128.5 [s, C4(SC6H4)],
127.6 [vt(br) + s, C2,6(PC6H5) and C2,6(SC6H4)]; 31P{1H}, δ 1.61
[20% intensity] (8+), -13.0 [100% intensity] (9) (br; peak half-
height ≈ 1 ppm). FAB-MS: m/ z (% abundance) [assignment]
949 (92) [M - Cl]+, 805 (5) [M - ClSPh]+, 687 (18) [M -
PPh3]+, 651 (4) [M - Cl - PPh3]+, 262 (32) [PPh3]+. Anal.
Found: C, 54.6; H, 4.1. Calcd for C44H35Cl2IrP2S3‚0.25C6H11
C, 54.3; H, 3.8.
:
Syn th esis of [Ir Cl(η2-SCSP h )(CS)(P P h 3)2]P F 6 (8.P F 6).
A solution of 1b (0.10 g, 0.13 mmol) in dichloromethane (20
cm3) and ethanol (15 cm3) was treated with ClC(dS)SPh (0.02
cm3, 0.027 g, 0.14 mmol), causing an immediate color change
to deep yellow. The mixture was stirred for 30 min and then
treated with K[PF6] (0.05 g, 0.27 mmol), and stirring was
continued for a further 1 h. The solvent was then removed
under reduced pressure and the residue extracted with dichlo-
romethane (2 × 10 cm3), and the combined extracts were
filtered through diatomaceous earth to remove KCl. The
filtrate was then diluted with ethanol (10 cm3). Slow conce-
tration of the solution under reduced pressure provided
crystals of 8‚PF6 which were isolated by filtration, washed with
ethanol (10 cm3) and light petroleum ether (10 cm3), and dried
in vacuo. Yield: 0.13 g (91%). IR (cm-1): in Nujol, 1360 (ν-
(CS)), 1124, 1042, 923. NMR (CDCl3, 25 °C): 1H, δ 6.35 [d, 2
H, J (HH) ) 6.9 Hz, H2,6(SPh)], 7.2-8.1 [m × 6, 33 H, H3-5(SPh)
and PPh]; 31P{1H}, δ 1.61; 13C{1H}, 250.9 [t, IrCS, J (PC) )
8.1 Hz], 241.5 [t, SCS, J (PC) ≈ 3.5 Hz], 135-124 [C6H5]. FAB-
MS: m/ z (% abundance) [assignment] 949 (100) [M]+, 687 (18)
[M - PPh3]+, 643 (2) [M - PPh3 - CS]+. Anal. Found: C,
48.2; H, 3.4. Calcd for C44H35ClF6IrP3S3: C, 48.3; H, 3.2.
Syn th esis of [Ir Cl2(CS)2(P P h 3)2]I3 (10‚X). (a) X ) I3:
F r om 9. A solution of 9 (0.10 g, 0.10 mmol) in tetrahydrofuran
(5 cm3) was treated with iodine (0.05 g, 2.0 mmol), and the
mixture was stirred for 10 min, resulting in the precipitation
of dark green crystals. These were isolated by filtration,
washed with benzene (10 cm3), and dried in vacuo. Yield:
0.075 g (61%). Comparable yields were obtained for runs
based on 0.40 g of 9.
C
45H37Cl2IrOP2S2: C, 55.0; H, 3.8.
Syn th esis of [Ir Cl2(CS2P h )(CO)(P P h 3)2] (7). Under an
atmosphere of dry dinitrogen, a suspension of 1a (0.50 g, 0.64
mmol) in dried and degassed tetrahydrofuran (30 cm3) was
treated with ClC(dS)SPh (0.10 cm3, 0.13 g, 0.71 mmol),
resulting in a deep orange solution being formed. The mixture
was stirred for 1 h and then diluted with ethanol (30 cm3).
Concentration under reduced pressure provided crystals of the
desired complex 7, which were isolated by filtration, washed
with ethanol (10 cm3) and light petroleum ether (10 cm3), and
dried in vacuo. Yield: 0.60 g (95%). IR (cm-1): in Nujol, 2069
(ν(CO)), 1009, 910 (ν(SCS)); in CH2Cl2, 2062 (ν(CO)). NMR
(CDCl3, 25 °C): 1H, δ ) 6.14 [d, 2 H, J (HH) ) 7.3 Hz, H2,6
-
(SC6H5)], 7.10, 7.20 [t × 2, 3 H, J (HH) ) 7.3 Hz, H3-5(SC6H5)],
7.33-8.00 [m, 30 H, PC6H5]; 13C{1H} δ 232.6 [t(br), SCS, J (PC)
not resolved], 156.0 [t(br), IrCO, J (PC) not resolved], 136.1 [s,
C1(SC6H4)], 135.3 , 130.8, 129.1, 127.9 [vt × 4, C(3,5),4,(2,6)
-
(PC6H5)], 133.7 [s, C3,5(SC6H4)], 128.6 [s, C4(SC6H4)], 128.4 [s,
C2,6(SC6H4)]; 31P{1H}, δ -17.3 (br; peak half-height ≈ 1 ppm).
FAB-MS: m/ z (% abundance) [assignment] 933 (92) [M - Cl]+,
905 (4) [M - Cl - CO]+, 796 (6) M - Cl - CO - SPh]+, 761
(3) M - 2Cl - CO - SPh]+, 643 (82) [M - Cl - CO - PPh3]+,
607 (12) [M - 2Cl - CO - PPh3]+. N.B.: The major
components of this spectrum correspond to those of 6‚PF6,
suggesting virtually complete ionization of 7 to 6+ in the nba
matrix. Anal. Found: C, 48.9; H, 3.3. Calcd for
(b) X ) I3: F r om 1b. A suspension of 1b (1.05 g, 1.32
mmol) in tetrahydrofuran (30 cm3) was treated with ClC(dS)-
SPh (0.20 cm3, 0.27 g, 1.43 mmol), resulting in dissolution of
1b. The mixture was stirred for 2 h and then treated with
iodine (0.68 g, 2.70 mmol) and stirred for a further 20 min.
The green crystals which formed were isolated by filtration
and washed with benzene (2 × 10 cm3) and dried in vacuo.
Yield: 1.46 g (88%).
C
44H35Cl2IrOP2S2‚2CH2Cl2: C, 48.6; H, 3.5.
Syn th esis of [Ir Cl(η2-SCSP h )(CO)(P P h 3)2]P F 6 (6‚P F 6).
A solution of 7 (0.20 g, 0.21 mmol) in dichloromethane (20 cm3)
IR (cm-1): in KBr disk, 1425, 1357 (ν(CS)); in CH2Cl2, 1436,

Thiocarbonyl Complexes of Iridium
Organometallics, Vol. 15, No. 18, 1996 3797
1365 (ν(CS)). NMR (CH2Cl2, 25 °C): 1H, δ 7.54, 8.04 [m × 2,
30 H, PC6H5]; 31P{1H}, δ -11.2. FAB-MS: m/ z (% abundance)
[assignment] 875 (0.5) [M]+. Anal. Found: C, 36.1; H, 2.5.
Calcd for C38H30Cl2I3IrP2S2: C, 36.3; H, 2.4.
a mixture of dichloromethane and hexane to provide 11‚Cl;
alternatively, the chloride counteranion could be metathesized
with ammonium hexafluorophosphate to provide the more
crystalline salt 11‚PF6. The residue was then dissolved in
dichloromethane (20 cm3), and this solution was treated with
a solution of NH4[PF6] (0.15 g, 0.92 mmol) in water (1 cm3)
and ethanol (20 cm3). Slow concentration of the mixture under
reduced pressure affected crystallization of 11‚PF6. Yield of
11‚Cl: 0.65 g (83%). IR (cm-1): in Nujol, 2171, 2141, 2112
(ν(CN)), 1283 (ν(CS)); in CH2Cl2, 2176, 2136, 2108 (ν(CN)),
1292 (ν(CS)). NMR (CDCl3, 25 °C): 1H, δ 1.80 [s, 12 H, CH3],
6.93 [d, 4 H, J (HH) ) 7.9 Hz, H4(C6H3)], 7.07 [t, 4 H, J (HH) )
7.9 Hz, H3,5(C6H3)], 7.39, 7.57 [m × 2, 30 H, PC6H5]; 13C{1H},
δ 283.4 [t, J (PC) ) 14.3 Hz, IrCS], 135.3-126.5 [C6H3 and C6H5
including 130.3 (vt, J (P2C) ) 30.3 Hz) for C1(PC6H5)], 18.2 [s,
CH3]; 31P{1H}, 7.53 [7.69 ppm for 9‚PF6]. FAB-MS (X )
C6H3Me2-2,6): m/ z (% abundance) [assignment] ) 1023 (12)
[M]+, 892 (89) [M - CNX]+, 796 (9) M - CNX + Cl]+, 761 (100)
[M - 2CNX]+, 717 (7) [M - CS - CNX]+, 630 (14) [M - PPh3]+,
497 (17) [M - PPh3 - CNX]+. Anal. Found: C, 58.0; H, 4.5;
N, 2.4. Calcd for C55H48ClIrN2P2S‚1.25(CH2Cl2): C, 58.0; H,
4.4; N, 2.4. The solvent of crystallization was confirmed by
NMR integration.
(c) X ) Cl: F r om 1b. In a similar manner to that described
in (b) above, a solution of 1b (0.15 g, 0.19 mmol) in tetrahy-
drofuran (5 cm3) was treated with ClC(dS)SPh (0.025 cm3,
0.033 g, 0.20 mmol), stirred for 2 h, and then treated with
iodine monochloride (0.035 g, 0.22 mmol). The resulting
orange solution was stirred for a further 20 min, during which
time orange crystals of the product formed, which were isolated
by filtration, washed with benzene (10 cm3), and dried in
vacuo. A further crop of crystals could be obtained by
concentration of the filtrate. Yield: 0.15 g (87%). IR (cm-1):
in Nujol, 1435, 1361 (ν(CS)); in CH2Cl2, 1438, 1369 (ν(CS)); in
KBr, 1425, 1357 (ν(CS)), 320, 300 (cis-ν(IrCl2)). NMR (CDCl3,
25 °C): 31P{1H}, δ -11.0; 13C{1H}, δ 232.4 [t, Ir(CS)2, J (PC) )
5.4 Hz], 134.9 [t, C3,5(PPh), J (PC) ) 4.5 Hz], 132.6 [s, C4(PPh)],
128.8 [t, C2,6(PPh), J (PC) ) 5.3 Hz], 126.8 [t, C1(PPh), J (PC)
) 30.3 Hz]. FAB-MS: m/ z (% abundance) [assignment] 875
(100) [M]+, 843 (9) [M - S]+, 615 (8) [M - PPh3]+, 541 (2) [M
- 2Cl - PPh3]+, 497 (10) [M - 2Cl - CS - PPh3]+, 297 (63)
[Ph3PCl]+, 262 (72) [PPh3]+.
Syn th esis of [Ir (CNC6H3Me2-2,6)2(CS)(P P h 3)2]Cl (11‚-
Cl). A solution of (4) (0.56 g, 0.67 mmol) in dichloromethane
(20 cm3) was treated with 2,6-dimethylphenyl isocyanide (0.18
g, 1.40 mmol), and the mixture was stirred for 1 h. The solvent
was then removed under reduced pressure and the residue
triturated with light petroleum ether to remove unreacted
isocyanide. The remaining residue could be crystallized from
Ack n ow led gm en t. We wish to thank the Engineer-
ing and Physical Sciences Research Council (U.K.) for
the award of a studentship (to J .D.E.T.W.-E.).
OM960205+