Synthesis and reactions of coordinatively unsaturated half-sandwich rhodium and iridium complexes having a 2,6-dimesitylbenzenethiolate ligand

Article abstract of DOI:10.1021/om100006r

Coordinatively unsaturated rhodium and iridium complexes bearing a bulky thiolate ligand, [Cp*M(SDmp)](BAr^F₄) (2a, M = Rh; 2b, M = Ir; Cp* = ?⁵-C₅Me₅; Dmp = 2,6-(mesityl)₂C₆H₃; Ar^F = 3,5-(CF₃)₂C₆H₃) were synthesized from the reactions of [Cp*MCl]₂(μ-Cl)₂ with LiSDmp and NaBAr^F₄. The metal centers in 2a and 2b weakly interact with the ipso-carbon of one of the mesityl groups in the SDmp ligand, while the ipso-carbon dissociates from the coordination sphere in the reactions with donor ligands. Treatment of 2a or 2b with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) led to the formation of [Cp*M(SDmp)(bpy)] (BAr^F₄) (3a, M = Rh; 3b, M = Ir) or [Cp*M(SDmp) (phen)](BAr^F₄) (4a, M = Rh; 4b, M = Ir), respectively. The reactions of 2a and 2b with 2 equiv of tert-butylisocianide or 1 atm of CO gave rise to the bis-adducts [Cp*M(SDmp)(L)₂](BAr^F ₄) (5a, M = Rh, L = CN^tBu; 5b, M = Ir, L = CN ^tBu; 6a, M = Rh, L = CO; 6b, M = Ir, L = CO). The coupling of terminal alkynes and SDmp took place upon the addition of excess 1-pentyne or phenylacetylene to solutions of 2a or 2b, affording cationic complexes with an S-arylated thiophene group, [Cp*M(?⁴-2, 4-R₂C ₄H₂S-Dmp)](BAr^F₄) (7a, M = Rh, R = ⁿPr; 7b, M = Ir, R = ⁿPr; 7c, M = Rh, R = Ph; 7d, M = Ir, R = Ph).

Full text of DOI:10.1021/om100006r

Organometallics 2010, 29, 1761–1770 1761
DOI: 10.1021/om100006r
Synthesis and Reactions of Coordinatively Unsaturated Half-Sandwich
Rhodium and Iridium Complexes Having a 2,6-Dimesitylbenzenethiolate
Ligand
Mayumi Sakamoto, Yasuhiro Ohki,* and Kazuyuki Tatsumi*
Department of Chemistry, Graduate School of Science and Research Center for Materials Science, Nagoya
University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
Received January 5, 2010
Coordinatively unsaturated rhodium and iridium complexes bearing a bulky thiolate ligand,
[Cp*M(SDmp)](BArF4) (2a, M = Rh; 2b, M = Ir; Cp* = η5-C5Me5; Dmp = 2,6-(mesityl)2C6H3;
ArF = 3,5-(CF3)2C6H3) were synthesized from the reactions of [Cp*MCl]2(μ-Cl)2 with LiSDmp and
NaBArF4. The metal centers in 2a and 2b weakly interact with the ipso-carbon of one of the mesityl
groups in the SDmp ligand, while the ipso-carbon dissociates from the coordination sphere in the
reactions with donor ligands. Treatment of 2a or 2b with 2,20-bipyridine (bpy) or 1,10-phenanthroline
(phen) led to the formation of [Cp*M(SDmp)(bpy)](BArF4) (3a, M=Rh; 3b, M=Ir) or [Cp*M-
(SDmp)(phen)](BArF4) (4a, M=Rh; 4b, M = Ir), respectively. The reactions of 2a and 2b with 2 equiv
of tert-butylisocianide or 1 atm of CO gave rise to the bis-adducts [Cp*M(SDmp)(L)2]-
(BArF ) (5a, M=Rh, L=CNtBu; 5b, M = Ir, L = CNtBu; 6a, M = Rh, L=CO; 6b, M = Ir, L =
4
CO). The coupling of terminal alkynes and SDmp took place upon the addition of excess 1-pentyne or
phenylacetylene to solutions of 2a or 2b, affording cationic complexes with an S-arylated thiophene group,
[Cp*M(η4-2, 4-R2C4H2S-Dmp)](BArF ) (7a, M = Rh, R = nPr; 7b, M = Ir, R = nPr; 7c, M = Rh, R =
Ph; 7d, M = Ir, R = Ph).
4
Introduction
toward H2 and other small molecules,2 (2) the synthesis of
biomimetic metal-sulfur clusters,3-5 and (3) the unique
coordination modes of thiolate ligands.2a,6 Among the bulky
thiolate ligands used for these studies, 2,6-di(mesityl)-
benzenethiolate (SDmp)7 is unique, in that mesityl carbons
are able to interact with metals in an η1- or η6-fashion. The
η1-interaction is labile,6b,8 and the dissociation of the mesityl
carbon from metal centers can create a reactive vacant site.
We have previously reported the synthesis and reactions of
Cp*Ru(SDmp) (Chart 1), in which the Ru atom forms an
η1-interaction with one of the mesityl ipso-carbons.6b This
complex was found to facilitate the trimerization of phenyl-
acetylene to afford the cationic arene complex [Cp*Ru(η6-
C6H3Ph3)](SDmp), with liberation of the SDmp ligand as
the counteranion. In this report, we extended our study on
the half-sandwich SDmp complex of ruthenium to the
analogous cationic complexes of rhodium and iridium,
Coordinatively unsaturated transition-metal thiolate
complexes are relatively rare but deserve particular interest
in terms of their relevancy to the active sites of cysteine-rich
metalloenzymes such as hydrogenases, acetyl CoA synthase,
CO dehydrogenases, and nitrogenases.1 We have been in-
vestigating coordinatively unsaturated thiolate complexes
with respect to (1) the reactions of metal-sulfur bonds
*Corresponding authors. E-mail: i45100a@nucc.cc.nagoya-u.ac.jp
(K.T.); ohki@mbox.chem.nagoya-u.ac.jp (Y.O.).
(1) Reviews of cysteine-rich metalloenzymes: (a) Rees, D. C.;
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Amara, P.; Cavazza, C.; Nicolet, Y.; Volbeda, A. Nature 2009, 460, 814–822.
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M.; Matsumoto, T.; Tatsumi, K. Inorg. Chem. 2009, 48, 2215–2223. (c)
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r
2010 American Chemical Society
Published on Web 03/11/2010
pubs.acs.org/Organometallics

1762 Organometallics, Vol. 29, No. 7, 2010
Sakamoto et al.
Chart 1
Scheme 1. Synthesis of Coordinatively Unsaturated Rh- and
Ir-SDmp Complexes 2a and 2b
Figure 1. Structure of the cation of 2a with thermal ellipsoids at
the 50% probability level.
˚
Table 1. Selected Bond Distances (A) and Angles (deg) for 2a and
2b
2a
2b
M-S
2.2280(8)
2.318(2)
1.752(2)
1.424(4)
1.394(5)
1.396(5)
1.371(5)
1.379(5)
1.437(4)
83.08(8)
105.95(11)
157.9(2)
2.229(2)
2.256(6)
1.761(6)
1.442(10)
1.405(12)
1.366(12)
1.382(12)
1.381(12)
1.412(10)
83.0(2)
M-C3
S-C1
C3-C4
C4-C5
C5-C6
C6-C7
C7-C8
C8-C3
[Cp*M(SDmp)](BArF4) (2a, M=Rh; 2b, M=Ir). As expec-
ted, these complexes were found to generate vacant metal
sites and to accommodate substrates. In contrast to Cp*Ru-
(SDmp), however, treatment of the rhodium and iridium
complexes with terminal alkynes led to the unexpected
coupling of the alkynes and SDmp ligand to produce the
S-arylated thiophene derivatives bound to the metals.
S-M-C3
M-S-C1
C2-C3-centroid(mesityl)
105.7(2)
152.7(5)
Ar = aryl), which serve as efficient catalysts for carbon-
nitrogen and carbon-carbon bond forming reactions.11 The
metal-bound mesityl groups in 2a and 2b are bent away from
the metals, as can be seen from the C2-C3-centroid-
(mesityl) angles of 157.9(2)° (2a) and 152.7(5)° (2b). These
angles are comparable to those of Cp*Ru(SDmp) (153.1°)6b
and the PR2(C6H4-2-Ar) complexes of palladium (141.7-
161.1°).11 Due to the M-C(ipso) interaction, the C3-C4 and
Results and Discussion
Synthesis and Structures of [Cp*M(SDmp)](BArF4) (2a,
M = Rh; 2b, M = Ir). We have reported that the reactions
of [Cp*MCl]2(μ-Cl)2 (M=Rh, Ir)9 with LiSDmp afford the
half-sandwich rhodium(III) and iridium(III) complexes
Cp*M(SDmp)(Cl) (1a, M=Rh; 1b, M= Ir).2b Treatment
˚
C3-C8 bonds (2a, 1.424(4), 1.437(4) A; 2b, 1.442(10),
ꢀ
(11) (a) Kocovsky, P.; Vyskocil, S.; Cısarova, I.; Sejbal, J.; Tislerova,
I.; Smrcina, M.; Lloyd-Jones, G. C.; Stephen, S. C.; Butts, C. P.; Murray,
ꢁ
ꢀ
ꢀ
ꢁ
ꢀ
ꢁ
ꢀ
of 1a and 1b with 1 equiv of NaBArF (ArF =3,5-(CF3)2-
4
M.; Langer, V. J. Am. Chem. Soc. 1999, 121, 7714–7715. (b) Barder, T. E.;
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C6H3)10 led to the removal of chloride, giving rise to the
cationic complexes [Cp*M(SDmp)](BArF4) (2a, M=Rh; 2b,
M = Ir) as green crystals with an 89% yield for both
(Scheme 1). These complexes are air- and moisture-sensitive
in solution and need to be handled under an inert atmos-
phere.
The molecular structures of 2a and 2b were determined by
X-ray crystallography. The cationic part of 2a is shown in
Figure 1, and selected bond distances and angles of 2a and 2b
are listed in Table 1. The cations of 2a and 2b have a
geometry very similar to that of the ruthenium(II) analogue
Cp*Ru(SDmp),6b and in fact the metal center interacts with
the ipso-carbon of one of the mesityl groups. Similar Pd---Ar
interactions are found in palladium complexes of ortho-
biaryl phosphines PR2(C6H4-2-Ar) (R = alkyl or phenyl,
(9) White, C.; Yates, A.; Maitlis, P. M. Inorg. Synth. 1992, 29, 228–
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3920–3922.

Article
Organometallics, Vol. 29, No. 7, 2010 1763
Scheme 2. Reactions of 2a and 2b with 2,20-Bipyridine and
1,10-Phenanthroline
˚
1.412(10) A) are slightly longer than the other C-C bonds in
˚
the mesityl ring (2a, 1.371(5)-1.396(5) A; 2b, 1.366(12)-
˚
1.405(12) A). Although the M-C(ipso) interaction is not
very strong, as manifested by the long M-C3 distances
˚
˚
of 2.318(2) A (2a) and 2.256(6) A (2b) relative to the M-
C(olefin) distances (2.08-2.24 A)12,13 and the M-C(arene)
˚
14,15
˚
distances (2.01-2.15 A),
stabilizing the coordinatively unsaturated metal center. The
M-C3 distance is longer for Rh (2a, 2.318(2) A) than Ir (2b,
2.256(6) A), while the reason is unclear. The Rh-S and Ir-S
bonds (2a, 2.2280(8) A; 2b, 2.229(2) A) are short compared
this interaction is effective in
˚
˚
˚
˚
with those of electronically saturated thiolate complexes of
16,17
˚
rhodium and iridium (2.32-2.38 A),
able, since 2a and 2b are electron deficient.
which is reason-
1
The H NMR spectra of 2a and 2b show that the two
mesityl groups of the SDmp ligand are inequivalent, where a
pair of signals were observed for the ortho- as well as the
para-methyls with the intensity ratio 6H(ortho):6H(ortho):
3H( para):3H( para). These signals did not show notable line-
broadning even at 80 °C. Thus the M-C(ipso) interaction is
likely retained in solution on the NMR time scale. The three
protons of the central phenyl group in the SDmp were also
found to be inequivalent, and one of the meta-protons shifts
to higher field at 6.41 ppm (2a) and 6.50 ppm (2b), respec-
tively. This upfield shift may be due to the ring-current effect
of the metal-bound mesityl group, since bending of the
mesityl ring makes it more facing toward one of the meta-
H of the central phenyl group.
the 18-electron complexes [Cp*M(SDmp)(bpy)](BArF4) (3a,
M = Rh; 3b, M = Ir), in which the SDmp ligand has no
metal-arene interaction (Scheme 2). In a similar manner, the
reactions with 1,10-phenanthroline (phen) afforded [Cp*M-
(SDmp)(phen)](BArF4) (4a, M = Rh; 4b, M = Ir). These
complexes were isolated as brown crystals in 80-90% yields.
In the 1H NMR spectra of these complexes, the two mesityl
groups of the SDmp ligand are equivalent, exhibiting single
ortho- and para-methyl signals with a 12H(ortho):6H( para)
intensity ratio.
Reactions of 2a and 2b with Small Molecules. The M-
C(ipso) interaction in 2a and 2b provides stability for the
coordinatively unsaturated metal center by blocking a po-
tential reaction site. On the other hand, dissociation of the
ipso-carbon from the coordination sphere apparently occurs,
allowing the following reactions with organic substrates.
Lability of the M-C(ipso) interaction also has been sug-
gested to be important for the high catalytic performance of
the palladium complexes bearing ortho-biaryl phosphines
PR2(C6H4-2-Ar).11
The X-ray analysis reveals a typical three-legged piano
stool geometry of 3 and 4, as shown in Figure 2. The M-S
˚
bond distances listed in Table 2 (2.3659(4)-2.3792(7) A) are
evidently longer than those of coordinatively unsaturated
complexes 2a and 2b, while they are comparable to those of
known 18-electron thiolate complexes of rhodium and ir-
idium.16,17 In the known [Cp*MX(bpy)]þ and [Cp*ML-
(bpy)]2þ complexes of Rh(III) and Ir(III), bpy coordinates
with a planar five-membered-ring geometry.18 In contrast,
the bpy ligand in 3a,b is bent toward the Cp* ligand,
distorting the ring from planarity. The dihedral angles
between the N1-M-N2 plane and the least-squared plane
of N1-C4-C5-N2 are 21.1(1)° (3a) and 20.2(2)° (3b). The
phen ligand in 4a,b is also bent, but to a lesser extent, with the
corresponding dihedral angles being 18.6(1)° for 4a and
8.7(4)° for 4b. Steric hindrance between the bpy/phen and
the SDmp ligands may contribute to the bending of these
chelating ligands. Interestingly, the bpy/phen aromatic rings
in 3a-4b are nearly parallel to one of the mesityl rings of
SDmp. The interplane angles are 11.1(1)° (3a), 12.4(2)° (3b),
4.7(1)° (4a), and 16.1(3)° (4b), and the shortest C-C contacts
A. 2,20-Bipyridine and 1,10-Phenanthroline. The reactions
of 2a and 2b with 1 equiv of 2,20-bipyridine (bpy) gave rise to
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˚
between the bpy/phen and mesityl carbons are 3.329(5) A
˚
˚
˚
(3a), 3.327(5) A (3b), 3.389(5) A (4a), and 3.149(2) A (4b).
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1764 Organometallics, Vol. 29, No. 7, 2010
Sakamoto et al.
Figure 2. Structures of the cations of 3a (left) and 4a (light) with thermal ellipsoids at the 50% probability level.
˚
Table 2. Selected Bond Distances (A) and Angles (deg) for Complexes 3a, 3b, 4a, 4b, 5b, and 6b
3a
3b
4a
4b
5b
6b
M-S
2.3765(7)
2.099(3)
2.103(3)
2.3792(7)
2.091(3)
2.087(3)
2.3659(4)
2.1064(18)
2.121(2)
2.3773(18)
2.099(6)
2.108(6)
2.4008(12)
1.950(6)
1.967(4)
1.134(8)
1.149(6)
1.780(3)
113.06(17)
88.86(14)
95.31(14)
94.9(2)
2.389(2)
1.905(8)
1.919(9)
1.123(10)
1.126(12)
1.778(7)
114.4(3)
93.0(2)
M-X1a
M-X2b
C2-Y1c
C3-Y2c
S-C1
1.786(3)
118.93(11)
90.79(7)
101.07(7)
76.08(13)
21.1(1)
1.793(3)
118.78(12)
99.98(8)
89.51(8)
75.60(14)
20.2(2)
1.773(2)
125.30(8)
89.44(5)
104.22(5)
77.50(9)
18.6(1)
1.784(6)
126.6(2)
87.43(18)
102.29(16)
77.4(2)
M-S-C1
S-M-X1a
S-M-X2b
X1-M-X2a,b
(N1-M-N2)-(N1-C4-C5-N2)d
M-C2-Y1c
M-C3-Y2c
88.3(2)
95.6(3)
8.7(4)
171.7(3)
172.7(5)
177.2(8)
173.0(7)
a X1 = N1 (3a, 3b, 4a, 4b), C2 (5b, 6b). b X2 = N2 (3a, 3b, 4a, 4b), C3 (5b, 6b). c For 5b and 6b: Y1 = C2 (5b), O1 (6b); Y2 = C3 (5b), O2 (6b).
d Interplane angles.
Scheme 3. Reactions of 2a and 2b with tert-Butyl Isocyanide and Carbon Monoxide
B. tert-Butyl Isocyanide and Carbon Monoxide. The reac-
tions of 2a,b with two-electron donors (L) such as CNtBu
and CO resulted in the formation of a series of bis-adducts
[Cp*M(SDmp)(L)2](BArF4) (5a, M = Rh, L = CNtBu; 5b,
M = Ir, L = CNtBu; 6a, M = Rh, L = CO; 6b, M = Ir, L =
CO), as shown in Scheme 3. Whereas the rhodium complexes
5a and 6a were formed in >90% yield according to the NMR
measurements, their isolation has been unsuccessful due to
instability in solution. The isocyanide complex 5a is gener-
ated cleanly at -40 °C, but it gradually decomposes at room
temperature. The carbonyl complex 6a is also labile, and
evaporation of the solution of 6a under reduced pressure
resulted in the dissociation of CO to reproduce 2a. In
contrast, the iridium congeners, 5b and 6b, are both stable,
and they were isolated as crystals. Their structures deter-
mined by X-ray diffraction studies are shown in Figure 3.
˚
The Ir-S bond distances of 5b (2.4008(12) A) and 6b
(2.389(2) A) are slightly longer than those of bpy/phen
˚
˚
˚
complexes 3b (2.3792(7) A) and 4b (2.3773(18) A), while
the coordination geometries are similar. In the 13C{1H}
NMR spectra, the coordinated carbon atoms of CNtBu
and CO were observed at 149.8 (5a), 149.9 (5b), 179.2 (6a),
and 184.2 (6b) ppm, respectively. The CtN or CtO bands in
the IR spectra appeared at 2202, 2185 cm-1 (5a), 2198, 2173
cm-1 (5b), 2125, 2100 cm-1 (6a), and 2116, 2083 cm-1 (6b).
C. 1-Pentyne and Phenylacetylene. When 2a or 2b was
treated with an excess of 1-pentylne or phenylacetylene, the
coupling of two alkynes and the SDmp ligand occurred in

Article
Organometallics, Vol. 29, No. 7, 2010 1765
Figure 3. Structures of the cations of 5b (left) and 6b (right) with thermal ellipsoids at the 50% probability level.
Scheme 4. Reactions of 2a and 2b with Terminal Alkynes
either case to give the S-arylated thiophene complexes
[Cp*M(η4-2,4-R2C4H2SDmp)](BArF4) (7a, M = Rh, R =
nPr; 7b, M = Ir, R = nPr; 7c, M = Rh, R = Ph; 7d, M = Ir,
R = Ph) (Scheme 4). S-Alkyl thiophene complexes of Cp*Ir
are known, which were formed by the alkylation of the pre-
formed η4-thiophene ligand by (R3O)BF4 (R = Me, Et).19
Figure 4. Structure of the cation of 7b with thermal ellipsoids at
the 50% probability level.
To our knowledge, the formation of a thiophene moiety from
alkynes and a thiolate ligand is unprecedented. NMR moni-
toring of the reaction mixtures revealed no isomers or
byproducts, indicating that the coupling of the SDmp ligand
with two alkyne molecules occurs regioselectively, providing
the 2,4-substituted S-aryl thiophene ligands. Complexes
7a-d were isolated as yellow crystals in 70-80% yields,
and they were characterized by the NMR spectra, elemental
˚
Table 3. Selected Bond Distances (A) and Angles (deg) for
Complexes 7a and 7b
7a
7b
M-S
2.7514(11)
1.803(5)
1.757(5)
1.422(7)
1.404(9)
1.425(10)
1.839(5)
85.4(2)
109.7(3)
112.4(5)
109.2(5)
112.6(4)
0.631(9)
28.8(3)
2.8134(10)
1.814(5)
1.763(5)
1.443(7)
1.429(8)
1.426(9)
1.833(4)
84.8(2)
109.3(3)
110.5(5)
109.6(4)
112.0(4)
0.712(8)
32.6(2)
1
S-C1
analysis, and X-ray crystallography. In the H NMR, the
S-C4
η4-thiophene ring of 7a-d gave rise to two singlets
found between 2.9-3.9 ppm and 4.3-5.4 ppm. The 13C{1H}
NMR of 7a-d exhibited four signals for the η4-thiophene
ring.
C1-C2
C2-C3
C3-C4
S-C5
C1-S-C4
The structures of 7a and 7b, determined by X-ray diffrac-
tion studies, include the unique metal-bound η4-S-arylated
thiophene ligand, as shown in Figure 4. Selected bond
S-C1-C2
C1-C2-C3
C2-C3-C4
C3-C4-S
(C1-C2-C3-C4)-Sa
(C1-C2-C3-C4)-(C1-S-C4)b
(19) Chen, J.; Angelici, R. J. Organometallics 1990, 9, 849–852.
(20) (a) Ogilvy, A. E.; Skaugset, A. E.; Rauchfuss, T. B. Organome-
tallics 1989, 8, 2739–2741. (b) Skaugset, A. E.; Rauchfuss, T. B.; Stern, C. L.
J. Am. Chem. Soc. 1990, 112, 2432–2433. (c) Luo, S.; Ogilvy, A. E.;
Rauchfuss, T. B.; Rheingold, A. L.; Wilson, S. R. Organometallics 1991, 10,
1002–1009.
(21) (a) Chen, J.; Angelici, R. J. Organometallics 1989, 8, 2277–2279.
(b) Chen, J.; Daniels, L. M.; Angelici, R. J. J. Am. Chem. Soc. 1990, 112,
199–204. (c) Chen, J.; Angelici, R. J. Organometallics 1990, 9, 879–880. (d)
Chen, J.; Daniels, L. M.; Angelici, R. J. J. Am. Chem. Soc. 1991, 113, 2544–
2552. (e) Chen, J.; Young, V. G.; Angelici, R. J. Organometallics 1996, 15,
2727–2734. (f) Chen, J.; Angelici, R. J. J. Organomet. Chem. 2001, 621, 55–
65.
a Distances between the C1-C4 plane and the sulfur atom. b Inter-
plane angles.
distances and angles are summarized in Table 3. The bond
lengths and angles of the thiophene ligands are comparable
to those of previously reported η4-thiophene complexes,19-21
˚
˚
and the long M-S distances (2.7514(11) A (7a), 2.8134(10) A
(7b)) indicate the absence of a direct M-S bonding interaction.
The sulfur atom bends away from the metal atom and is

1766 Organometallics, Vol. 29, No. 7, 2010
Sakamoto et al.
Scheme 5. Possible Pathway for the Formation of 7
relevant to C, Cp*Ir{SC(Me)dCH-CHdC(Me)}, forms an
S-bound BH3 adduct, promoting ring closure to generate an
η4-thiophene complex.19 An alternative pathway to 7 may be
the initial formation of a metallacyclopentadiene intermedi-
ate via cycloaddition of two alkynes at the metal center,
followed by successive formation of two S-C bonds. How-
ever, we assume this latter pathway is less likely, because a
metallacyclopentadiene intermediate would be a relatively
uncommon Rh(V)/Ir(V) species.
Conclusions
Coordinatively unsaturated half-sandwich rhodium(III)
and iridium(III) complexes 2a and 2b carrying a bulky
thiolate ligand SDmp have been successfully synthesized.
These complexes feature the M-C(ipso) interaction, which
provides stability for the metal center by occupying the
reactive sites and by the relief of electron deficiency. These
complexes react with Lewis bases via dissociation of the ipso-
carbon from the metal centers, as demonstrated by the facile
formation of a series of 18-electron complexes with 2,20-
bipyridine, 1,10-phenanthroline, tert-butylisocyanide, and
carbon monoxide. The reactions of 2a and 2b with 1-pentyne
or phenylacetylene, which result in the formation of S-
arylated thiophenes, are a new class of coupling reactions
between metal-thiolates and alkynes. Interestingly, the reac-
tivity of 2a,b toward alkynes is different from that of isostruc-
tural complex Cp*Ru(SDmp). A possible reason for the
difference is the cationic charge of the rhodium and iridium
complexes, and the cationic charge probably prevents the
dissociation of the SDmp anion that is required for the
cyclotrimerization of alkynes mediated by Cp*Ru(SDmp).
This cationic charge also results in the less efficient RhfCO
π-back-donation, facilitating the dissociation of CO from 6a
under reduced pressure.
˚
displaced from the plane of thiophene carbons by 0.631(9) A
˚
(7a) and 0.712(8) A (7b). The angles between the planes defined
by C1-C2-C3-C4 and C1-S-C4 are 28.8(3)° (7a) and
32.6(2)° (7b). The S-arylated-thiphene sulfur is substantially
pyramidalized, and it may have some character of sulfonium
cation. If the cation center of 7a and 7b resides in the sulfur
atom, the oxidation state of rhodium and iridium is regarded
as þI. The S-C bond length varies from the long S-C5(Dmp)
˚
˚
distances (1.839(5) A (7a), 1.833(4) A (7b)), to the intermediary
˚
˚
S-C1 distances (1.803(5) A (7a), 1.814(5) A (7b)), to the short
˚
˚
S-C4 distances (1.757(5) A (7a), 1.763(5) A (7b)). A similar
long S-C distance is found in the analogous S-methylated
thiophene complex of iridium, [Cp*Ir(η4-2,5-Me2C4H2-
SCH3)]þ (S-CH3; 1.83(1) A).
21f
˚
A reaction pathway for the formation of 7 is proposed in
Scheme 5. The reaction is initiated by coordination of an
alkyne at the coordinatively unsaturated metal center (A).
The insertion of the η2-alkyne into the M-S bond follows,
where the substituent R of alkyne orients away from the
bulky Dmp group of thiolate, generating B selectively.
Another alkyne molecule is inserted into the M-C bond of
B, and a six-membered metallacycle is formed (C). This
reaction occurs regioselectively, in such a way that two
alkynes couple in a head-to-tail manner to avoid the steric
repulsion between two R groups of the alkynes. Attempts to
observe the intermediary species such as B or C have been
unsuccessful. The 1H NMR monitoring of the reaction
mixtures of 2a,b and 1-2 equiv of alkynes gave the signals
of only 7a-d other than those of 2a,b, probably because of
the relatively slow dissociation of the M-C(ipso) interaction
in 2a,b rather than the following steps. Formation of a six-
membered metallacycle analogous to C was observed for a
half-sandwich rhodium complex of 1,2-dicarba-closo-dode-
caborane-1,2-dithiolate, via the regioselective insertion of
two alkyne molecules into the Rh-S(thiolate) bond.22 At the
final step, the thioether sulfur of C forms a bond with the
metal-bound carbon atom, resulting in generation of 7.
Although the driving force for the C-S coupling is unclear,
it is interesting to note that a metallacycle complex of iridium
Experimental Section
General Procedures. All reactions were carried out under a
nitrogen or argon atmosphere using standard Schlenk techni-
ques. THF, toluene, Et2O, dichloromethane, and hexane were
purified by the method of Grubbs,23 where the solvents were
passed over columns of activated alumina and a supported
copper catalyst supplied by Hansen & Co. Ltd. CDCl3 was
dried over CaH2 and distilled prior to use. 1H and 13C{1H}
NMR spectra were acquired on a JEOL ECA-600 or Varian
1
INOVA-500. H NMR signals were referenced to the residual
proton peak of the deuterated solvent. The 13C chemical shifts
were relative to the carbon signals for the deuterated solvents.
Infrared spectra were recorded on a JASCO FT/IR-410 spectro-
meter. Elemental analyses were performed on a LECO-CHNS-
932 elemental analyzer where the crystalline samples were sealed
in silver capsules under nitrogen. X-ray diffraction data were
collected on a Rigaku AFC8 equipped with a CCD area detector
using graphite-monochromatized Mo KR radiation. Complexes
1a and 1b2b and NaBArF 10 were prepared according to the
4
literature procedures.
Synthesis of [Cp*Rh(SDmp)](BArF4) (2a). Complex 1a (85.1
mg, 0.138 mmol), NaBArF (122.1 mg, 0.138 mmol), and
4
dichloromethane (40 mL) were charged into a Schlenk tube,
and the mixture was stirred at room temperature for 2 h.
The solution was centrifuged to remove NaCl, and then the
solvent was removed under reduced pressure to afford a
green solid. After washing with hexane (3 mL), the product
(22) Herberhold, M.; Yan, H.; Milius, W.; Wrackmeyer, B. Chem.;
Eur. J. 2000, 6, 3026–3032.
(23) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518–1520.

Article
Organometallics, Vol. 29, No. 7, 2010 1767
was dissolved in Et2O and the solution was stored at -30 °C.
[Cp*Rh(SDmp)](BArF4) (2a) (183.8 mg, 0.123 mmol, 89%
yield) was obtained as green crystals. 1H NMR (CDCl3): δ
7.70 (bs, 8H, o-H of ArF), 7.53 (bs, 4H, p-H of ArF), 7.31 (t, J =
7.5 Hz, 1H, p-H of SC6H3Mes2), 7.52, 7.00 (s, 2H, m-H of Mes),
7.14, 6.41 (d, J = 7.5 Hz, 1H, m-H of SC6H3Mes2), 2.62, 2.38 (s,
3H, p-CH3 of Mes), 1.94, 1.73 (s, 6H, o-CH3 of Mes), 1.28 (s,
15H, Cp*). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.2 Hz,
ipso-C of ArF), 149.1, 145.2, 140.7, 137.7, 137.5, 136.0 (s, Ar),
135.5, 135.4 (s, m-C of Mes), 134.8 (s, o-C of ArF), 130.1 (s, p-C
of SC6H3Mes2), 129.0 (q, JFC = 30.9 Hz, m-C of ArF), 128.3,
126.0 (s, m-C of SC6H3Mes2), 124.5 (q, JFC = 271.4 Hz, CF3),
117.5 (s, p-C of ArF), 100.6 (d, JRhC = 8.0 Hz, C5(CH3)5), 21.8,
21.1 (s, p-CH3 of Mes), 20.4, 20.2 (s, o-CH3 of Mes), 9.3 (d,
SC6H3Mes2), 6.64 (s, 4H, m-H of Mes), 2.26 (s, 6H, p-CH3 of
Mes), 1.80 (s, 12H, o-CH3 of Mes), 0.92 (s, 15H, Cp*). 13C{1H}
NMR (CDCl3): δ 161.7 (q, JBC = 49.8 Hz, ipso-C of ArF), 154.5,
148.4, 140.8, 136.7, 135.5, 135.4 (s, Ar), 151.8, 138.6, 125.8,
122.3 (s, bpy), 134.7 (s, o-C of ArF), 130.0 (s, m-C of
SC6H3Mes2), 128.9 (q, JFC =31.1 Hz, m-C of ArF), 128.1 (s,
m-C of Mes), 127.5 (s, p-C of SC6H3Mes2), 124.5 (q, JFC = 272.7
Hz, CF3), 117.5 (s, p-C of ArF), 90.9 (s, C5(CH3)5), 21.6 (s, o-
CH3 of Mes), 20.9 (s, p-CH3 of Mes), 6.7 (s, C5(CH3)5). Anal.
Calcd for C76H60SN2F24BIr: C, 53.94; H, 3.57; N, 1.66; S, 1.89.
Found: C, 53.52; H, 3.59; N, 1.86; S, 1.92.
Synthesis of [Cp*Rh(SDmp)(phen)](BArF4) (4a). The synthetic
procedure is analogous to that of 3a. The reaction of 2a (113.6
mg, 0.076 mmol) with 1,10-phenanthroline (13.3 mg, 0.074
mmol) in toluene (30 mL) gave a brown solid, from which
brown crystals of [Cp*Rh(SDmp)(phen)](BArF4) (4a) (110.6
mg, 0.068 mmol, 89% yield) were obtained. 1H NMR
(CDCl3): δ 8.46 (d, J=5.5 Hz, 2H, phen), 8.33 (d, J = 8.3 Hz,
2H, phen), 7.84 (s, 2H, phen), 7.66 (m, 15H, phen þ o-H of ArF),
7.46 (bs, 4H, p-H of ArF), 6.94 (t, J = 7.6 Hz, 1H, p-H of
SC6H3Mes2), 6.59 (d, J = 7.6 Hz, 2H, m-H of SC6H3Mes2), 6.48
(s, 4H, m-H of Mes), 2.23 (s, 6H, p-CH3 of Mes), 1.55 (s, 12H, o-
CH3 of Mes), 0.88 (s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ
161.7 (q, JBC = 49.3 Hz, ipso-C of ArF), 154.5, 151.8, 137.7,
126.3, 125.9, 125.3 (s, phen), 148.1, 145.4, 140.9, 139.2, 135.3,
130.2 (s, Ar), 134.8 (s, o-C of ArF), 129.6 (s, m-C of SC6H3Mes2),
128.9 (q, JFC=28.6 Hz, m-C of ArF), 128.2 (s, p-C of SC6H3-
Mes2), 127.8 (s, m-C of Mes), 124.5 (q, JFC = 264.3 Hz, CF3),
117.4 (s, p-C of ArF), 97.3 (d, JRhC=7.5 Hz, C5(CH3)5), 20.9 (s,
o-CH3 of Mes), 20.8 (s, p-CH3 of Mes), 7.2 (s, C5(CH3)5). Anal.
Calcd for C78H60SN2F24BRh: C, 57.58; H, 3.72; N, 1.72; S, 1.97.
Found: C, 57.57; H, 4.06; N, 1.80; S, 1.84.
JRhC = 2.4 Hz, C5(CH3)5). Anal. Calcd for C66H52SF24BRh: C,
54.79; H, 3.62; S, 2.22. Found: C, 54.43; H, 3.62; S, 2.25.
Synthesis of [Cp*Ir(SDmp)](BArF4) (2b). The procedure is
similar to the one used for the synthesis of 2a. The reaction of
1b (65.1 mg, 0.092 mmol) with NaBArF4 (83.3 mg, 0.094 mmol)
in dichloromethane (40 mL) at room temperature afforded a
dark green solid. Dark green crystals of [Cp*Ir(SDmp)](BArF
)
4
(2b) (125.8 mg, 0.082 mmol, 89% yield) were grown from its
Et2O solution at -30 °C. 1H NMR (CDCl3): δ 7.67 (bs, 8H, o-H
of ArF), 7.51 (bs, 4H, p-H of ArF), 7.31 (t, J = 7.5 Hz, 1H, p-H of
SC6H3Mes2), 7.45, 6.98 (s, 2H, m-H of Mes), 7.10, 6.50 (d, J =
7.5 Hz, 1H, m-H of SC6H3Mes2), 2.76, 2.38 (s, 3H, p-CH3 of
Mes), 1.92, 1.64 (s, 6H, o-CH3 of Mes), 1.26 (s, 15H, Cp*).
13C{1H} NMR (CDCl3): δ 161.6 (q, JBC = 49.0 Hz, ipso-C of
ArF), 153.9, 148.5, 144.7, 142.4, 140.4, 137.7, 135.9 (s, Ar), 134.8
(s, o-C of ArF), 134.1, 128.3 (s, m-C of Mes), 130.6 (s, p-C of
SC6H3Mes2), 128.9 (q, JFC = 33.2 Hz, m-C of ArF), 128.5, 128.3
(s, m-C of SC6H3Mes2), 124.5 (q, JFC = 272.4 Hz, CF3), 117.4 (s,
p-C of ArF), 94.3 (s, C5(CH3)5), 21.6, 21.2 (s, p-CH3 of Mes),
21.0, 20.2 (s, o-CH3 of Mes), 9.1 (s, C5(CH3)5). Anal. Calcd for
C66H52SF24BIr: C, 51.60; H, 3.41; S, 2.09. Found: C, 51.26; H,
3.38; S, 2.19.
Synthesis of [Cp*Ir(SDmp)(phen)](BArF4) (4b). The synthetic
procedure is analogous to that of 3a. The reaction of 2b (101.5
mg, 0.066 mmol) with 1,10-phenanthroline (11.8 mg, 0.066
mmol) in toluene (20 mL) afforded a brown solid, from which
Synthesis of [Cp*Rh(SDmp)(bpy)](BArF4) (3a). Complex 2a
(481.4 mg, 0.322 mmol), 2,20-bipyridine (50.2 mg, 0.321 mmol),
and toluene (30 mL) were charged into a Schlenk tube, and the
mixture was stirred at room temperature for 3 h. The solvent was
removed under reduced pressure, and the residue was washed
with hexane (3 mL) to give a brown solid. Brown crystals of
[Cp*Rh(SDmp)(bpy)](BArF4) (3a) (438.8 mg, 0.274 mmol, 85%
yield) were grown at room temperature from a toluene solution
layered with hexane. 1H NMR (CDCl3): δ 8.13 (d, J = 4.8 Hz,
2H, bpy), 7.91 (d, J = 7.9 Hz, 2H, bpy), 7.86 (dt, J = 7.9, 1.4 Hz,
2H, bpy), 7.71 (bs, 8H, o-H of ArF), 7.50 (bs, 4H, p-H of ArF),
7.35 (dt, J = 7.6, 1.7 Hz, 2H, bpy), 7.02 (t, J = 7.6 Hz, 1H, p-H
of SC6H3Mes2), 6.69 (d, J = 7.3 Hz, 2H, m-H of SC6H3Mes2),
6.63 (s, 4H, m-H of Mes), 2.25 (s, 6H, p-CH3 of Mes), 1.78 (s,
12H, o-CH3 of Mes), 0.89 (s, 15H, Cp*). 13C{1H} NMR
(CDCl3): δ 161.6 (q, JBC = 50.0 Hz, ipso-C of ArF), 153.4,
148.1, 140.8, 139.1, 135.4 (s, Ar), 152.3, 152.2, 138.8, 122.3 (s,
bpy), 134.7 (s, o-C of ArF), 129.7 (s, p-C of SC6H3Mes2), 128.9
(q, JFC=30.7 Hz, m-C of ArF), 128.0 (s, m-C of Mes), 127.5 (s,
m-C of SC6H3Mes2), 124.5 (q, JFC = 272.7 Hz, CF3), 117.4 (s, p-
C of ArF), 97.4 (d, JRhC=4.8 Hz, C5(CH3)5), 21.4 (s, o-CH3 of
Mes), 20.9 (s, p-CH3 of Mes), 7.1 (s, C5(CH3)5). Anal. Calcd for
C76H60SN2F24BRh: C, 56.94; H, 3.77; N, 2.00; S, 1.75. Found:
C, 56.61; H, 3.61; N, 1.92; S, 1.82.
brown crystals of [Cp*Ir(SDmp)(phen)](BArF4) 1/2C6H14
3
(4b 1/2C6H14) (104.2 mg, 0.059 mmol, 90% yield) were ob-
3
tained. 1H NMR (CDCl3): δ 8.52 (d, J = 5.0 Hz, 2H, phen), 8.26
(d, J = 8.1 Hz, 2H, phen), 7.85 (s, 2H, phen), 7.69 (m, 10H,
phen þ o-H of ArF), 7.48 (bs, 4H, p-H of ArF), 6.93 (t, J = 7.6
Hz, 1H, p-H of SC6H3Mes2), 6.59 (d, J=7.6 Hz, 2H, m-H of
SC6H3Mes2), 6.51 (s, 4H, m-H of Mes), 2.25 (s, 6H, p-CH3 of
Mes), 1.57 (s, 12H, o-CH3 of Mes), 0.92 (s, 15H, Cp*). 13C{1H}
NMR (CDCl3): δ 161.7 (q, JBC = 49.8 Hz, ipso-C of ArF), 151.0,
137.8, 136.9, 135.2, 126.3, 125.7 (s, phen), 148.3, 147.0, 140.8,
135.3, 130.4 (s, Ar), 134.8 (s, o-C of ArF), 129.8 (s, p-C of
SC6H3Mes2), 129.0 (q, JFC = 31.1 Hz, m-C of ArF), 127.9 (s, m-
C of Mes), 127.6 (s, m-C of SC6H3Mes2), 124.9 (q, JFC=272.8
Hz, CF3), 117.5 (s, p-C of ArF), 90.9 (s, C5(CH3)5), 21.1 (s, o-
CH3 of Mes), 20.9 (s, p-CH3 of Mes), 6.8 (s, C5(CH3)5). Anal.
Calcd for C78H60SN2F24BIr: C, 54.58; H, 3.52; N, 1.63; S, 1.83.
Found: C, 54.57; H, 3.82; N, 1.72; S, 2.21.
Formation of [Cp*Rh(SDmp)(CNtBu)2](BArF4) (5a). (A)
NMR experiment: A 1.0 M CDCl3 solution of tert-butyl iso-
cyanide (20.7 μL, 0.021 mmol) was added to a CDCl3 (0.6 mL,
with 1% Si(SiMe3)4 as the internal standard) solution of 2a (15.5
mg, 0.010 mmol) at -40 °C, and the mixture was left at this
1
temperature for 3 h. The H NMR spectrum of the resultant
yellowish-brown solution revealed the disappearance of 2a and
the formation of [Cp*Rh(SDmp)(CNtBu)2](BArF4) (5a; 93%
yield based on the internal standard) together with a small
amount of unidentified products. (B) Preparative scale: A
1.0 M toluene solution of tert-butyl isocyanide (156.0 μL,
0.156 mmol) was added to a toluene (20 mL) solution of 2a
(117.0 mg, 0.078 mmol) at -40 °C, and the mixture was stirred
for 1 h. The volatile materials were removed under vacuum at
-40 °C, and the residue was washed with hexane (3 mL) to give a
Synthesis of [Cp*Ir(SDmp)(bpy)](BArF4) (3b). The synthetic
procedure is analogous to that of 3a. The reaction of 2b (198.2
mg, 0.114 mmol) with 2,20-bipyridine (19.8 mg, 0.127 mmol) in
toluene (20 mL) afforded a greenish-brown solid, from which
[Cp*Ir(SDmp)(bpy)](BArF4) (3b) (175.6 mg, 0.104 mmol, 91%
yield) was obtained as brown crystals. 1H NMR (CDCl3): δ 8.21
(d, J = 5.0 Hz, 2H, bpy), 7.90 (d, J = 7.9 Hz, 2H, bpy), 7.78 (t,
J = 7.7 Hz, 2H, bpy), 7.69 (bs, 8H, o-H of ArF), 7.50 (bs, 4H,
p-H of ArF), 7.32 (t, J = 5.6 Hz, 2H, bpy), 7.00 (t, J = 7.4 Hz,
1H, p-H of SC6H3Mes2), 6.68 (d, J = 7.4 Hz, 2H, m-H of
yellow solid (114.0 mg) of [Cp*Rh(SDmp)(CNtBu)2](BArF
)
4
(5a) with some impurities. We have been unable to obtain

1768 Organometallics, Vol. 29, No. 7, 2010
Sakamoto et al.
satisfactory elemental analysis on this compound. 1H NMR
(CDCl3, -40 °C): δ 7.66 (bs, 8H, ArF), 7.50 (bs, 4H, ArF), 7.17
(t, J = 7.4 Hz, 1H, p-H of SC6H3Mes2), 6.95 (m, 6H, m-H of
SC6H3Mes2 þ m-H of Mes), 2.31, 2.21 (bs, 6H, o-CH3 of Mes),
2.00 (br, 6H, p-CH3 of Mes), 1.37 (s, 15H, Cp*), 1.21 (bs, 18H,
CO via freeze-pump-thaw cycles, and the mixture was stirred
for 3 h at room temperature. Slow evaporation of the solvent
under reduced pressure gave pink crystals of [Cp*Ir-
(SDmp)(CO)2](BArF4) (C7H8) (6b C7H8) (108.2 mg, 0.064
3
3
mmol, 97% yield). H NMR (CDCl3): δ 7.66 (bs, 8H, ArF),
7.51 (bs, 4H, ArF), 7.41 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2),
7.11 (d, J=7.6 Hz, 2H, m-H of SC6H3Mes2), 6.95 (s, 4H, m-H of
Mes), 2.29 (s, 6H, p-CH3 of Mes), 2.07 (s, 12H, o-CH3 of Mes), 1.67
(s, 15H, Cp*). 13C{1H} NMR (CDCl3): δ 184.2 (s, CO), 161.6 (q,
1
CNtBu). 13C{1H} NMR (CDCl3, -40 °C): δ 161.4 (q, JBC
=
48.7 Hz, ipso-C of ArF), 149.8 (br, CNC(CH3)3), 141.1, 140.9,
137.6 (s, Ar), 134.5 (s, o-C of ArF), 130.0 (s, m-C of SC6H3Mes2),
128.5 (q, JFC = 28.4 Hz, m-C of ArF), 128.3 (s, m-C of Mes),
127.1 (s, p-C of SC6H3Mes2), 124.3 (q, JFC = 273.9 Hz, CF3),
117.3 (s, p-C of ArF), 104.3 (s, C5(CH3)5), 59.4 (s, CNC(CH3)3),
30.2 (s, CNC(CH3)3), 21.3 (bs, p-CH3 of Mes), 21.0 (s, o-CH3 of
Mes), 8.5 (s, C5(CH3)5). IR (KBr, cm-1): νCN = 2202, 2185.
Synthesis of [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b). A 1.0 M
toluene solution of tert-butyl isocyanide (143.8 μL, 0.144 mmol)
was added to a toluene (20 mL) solution of 2b (100.4 mg, 0.065
mmol), and the mixture was stirred for 3 h at room temperature.
The volatile materials were removed under reduced pressure,
and the residue was washed with hexane (3 mL) to give a yellow
solid. Yellow crystals of [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b)
(83.1 mg, 0.049 mmol, 75% yield) were obtained from a CH2Cl2
J
BC =49.8 Hz, ipso-C of ArF), 158.7, 149.0, 138.6, 137.6, 135.5,
133.8 (s, Ar), 134.7 (s, o-C of ArF), 131.0 (s, m-C of SC6H3Mes2),
130.0 (s, p-C of SC6H3Mes2), 128.9 (q, JFC=31.1 Hz, m-C of ArF),
128.9 (s, m-C of Mes), 124.5 (q, JFC=272.8 Hz, CF3), 117.5 (s, p-C
of ArF), 107.7 (s, C5(CH3)5), 20.8 (s, o-CH3 of Mes), 15.3 (s, p-CH3
of Mes), 8.1 (s, C5(CH3)5). IR (KBr, cm-1): νCO = 2119, 2084. IR
(CDCl3, cm-1): νCO=2116, 2083. Anal. Calcd for C68H52BF24O2-
SIr C7H8: C, 53.48; H, 3.59; S, 1.90. Found: C, 53.01; H, 3.60;
3
S, 1.84.
Synthesis of [Cp*Rh(η4-2,4-nPr2C4H2SDmp)](BArF4) (7a).
Complex 2a (101.8 mg, 0.070 mmol), 20 equiv of 1-pentyne
(138.7 μL, 0.141 mmol), and dichloromethane (20 mL) were
charged into a Schlenk tube, and the mixture was stirred at room
temperature for 3 h. The volatile materials were removed under
vacuum, and the residue was washed with hexane (3 mL) to give
a yellow solid. Yellow crystals of [Cp*Rh(η4-2,4-nPr2C4H2-
SDmp)](BArF4) (7a) (83.7 mg, 0.053 mmol, 75% yield) were
obtained from a CH2Cl2 solution layered with hexane at room
temperature. Carbon atoms of η4-2,4-R2C4H2SDmp are num-
bered as shown below. 1H NMR (CDCl3): δ 7.89 (bs, 8H, ArF),
7.59 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H, ArF),
7.09 (d, J=7.6 Hz, 2H, m-H of SC6H3Mes2), 7.02 (s, 4H, m-H of
Mes), 4.43 (s, 1H, H-C2 in SC4H2(C2H4CH3)2), 2.88 (s, 1H,
H-C4 in SC4H2(C2H4CH3)2), 2.37 (s, 6H, p-CH3 of Mes), 1.98,
1.93 (s, 6H, o-CH3 of Mes), 1.56 (s, 15H, Cp*), 2.13, 1.68, 1.43,
1.20 (m, 2H, SC4H2(C2H4CH3)2), 1.48, 0.87 (t, J=5.5 Hz, 3H,
1
solution layered with hexane at room temperature. H NMR
(CDCl3): δ 7.68 (bs, 8H, ArF), 7.52 (bs, 4H, ArF), 7.18 (t, J = 7.6
Hz, 1H, p-H of SC6H3Mes2), 6.92 (s, 4H, m-H of Mes), 6.87 (d,
J = 7.6 Hz, 2H, m-H of SC6H3Mes3), 2.32 (s, 6H, p-CH3 of
Mes), 2.16 (bs, 12H, o-CH3 of Mes), 1.49 (s, 15H, Cp*), 1.26 (s,
18H, CNtBu). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 49.8
Hz, ipso-C of ArF), 149.9 (s, CNC(CH3)3), 141.3, 138.9, 136.2 (s,
Ar), 134.8 (s, o-C of ArF), 130.5 (s, m-C of SC6H3Mes2), 129.0
(q, JFC = 31.1 Hz, m-C of ArF), 128.8 (s, m-C of Mes), 127.3 (s,
p-C of SC6H3Mes2), 124.5 (q, JFC =272.8 Hz, CF3), 117.4 (s,
p-C of ArF), 100.3 (s, C5(CH3)5), 59.8 (s, CNC(CH3)3), 30.0 (s,
CNC(CH3)3), 22.2 (bs, p-CH3 of Mes), 20.9 (s, o-CH3 of Mes),
7.9 (s, C5(CH3)5). IR (KBr, cm-1): νCN = 2198, 2173. Anal.
Calcd for C76H70BF24N2SIr: C, 53.62; H, 4.14; N, 1.65; S, 1.88.
Found: C, 53.53; H, 4.32; N, 1.79; S, 1.70.
SC4H2(C2H4CH3)2). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC
=
Formation of [Cp*Rh(SDmp)(CO)2](BArF4) (6a). An NMR
tube equipped with a J-Young valve was charged with 2a (10.0
mg, 0.007 mmol) and CDCl3 (0.6 mL, with 1% Si(SiMe3)4 as the
internal standard). After freeze-pump-thaw cycles, 1 atm of
CO was charged into the tube at room temperature. The color of
50.4 Hz, ipso-C of ArF), 141.0, 139.0, 136.1, 134.3 (s, Ar), 134.8
(s, o-C of ArF), 133.5 (s, p-C of SC6H3Mes2), 131.6 (s, m-C of
SC6H3Mes2), 128.9 (q, JFC = 30.3 Hz, m-C of ArF), 128.7, 128.6
(s, m-C of Mes), 124.5 (q, JFC=271.5 Hz, CF3), 117.4 (s, p-C of
ArF), 99.0 (C3 in SC4H2(C2H4CH3)2), 98.1 (d, JRhC=5.8 Hz,
C5(CH3)5), 75.3 (d, JRhC=5.8 Hz, C2 in SC4H2(C2H4CH3)2),
65.7 (d, JRhC = 13.0 Hz, C1 in SC4H2(C2H4CH3)2), 43.2 (d,
1
the solution immediately became lighter. The H NMR spec-
trum revealed the quantitative formation of [Cp*Rh(SDmp)-
(CO)2](BArF4) (6a). Removal of CO from the reaction mixture
by three freeze-pump-thaw cycles followed by purging with
N2 resulted in the regeneration of 2a (94%), leaving a small
amount of 6a (6%). Isolation of 6a has not been successful. 1H
NMR (CDCl3): δ 7.67 (bs, 8H, ArF), 7.51 (bs, 4H, ArF), 7.45 (t,
J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 7.11 (d, J = 7.6 Hz, 2H, m-
H of SC6H3Mes2), 6.95 (s, 4H, m-H of Mes), 2.29 (s, 6H, p-CH3
of Mes), 2.06 (s, 12H, o-CH3 of Mes), 1.54 (s, 15H, Cp*).
13C{1H} NMR (CDCl3): δ 179.2 (d, JRhC = 63.3 Hz, CO),
160.9 (q, JBC = 49.8 Hz, ipso-C of ArF), 148.4, 138.0, 136.8,
134.7 (s, Ar), 134.0 (s, o-C of ArF), 130.1 (s, m-C of SC6H3Mes2),
129.6 (s, p-C of SC6H3Mes2), 128.1 (q, JFC=32.1 Hz, m-C of
ArF), 128.0 (s, m-C of Mes), 123.7 (q, JFC =272.8 Hz, CF3),
116.7 (s, p-C of ArF), 110.7 (d, JRhC = 3.0 Hz, C5(CH3)5), 20.1
(s, o-CH3 of Mes), 20.0 (s, p-CH3 of Mes), 8.0 (s, C5(CH3)5). IR
(CDCl3, cm-1): νCO = 2125, 2100.
J
RhC = 14.4 Hz, C4 in SC4H2(C2H4CH3)2), 29.4, 28.8, 21.3, 20.6
(s, SC4H2(C2H4CH3)2), 21.2 (s, p-CH3 of Mes), 20.9, 20.8 (s,
o-CH3 of Mes), 13.9, 13.5 (s, SC4H2(C2H4(CH3)2), 9.3 (s, C5-
(CH3)5). Anal. Calcd for C78H76SF24BRh: C, 58.00; H, 4.74; S,
1.99. Found: C, 57.80; H, 4.41; S, 1.81.
Synthesis of [Cp*Ir(η4-2,4-nPr2C4H2SDmp)](BArF4) (7b). The
synthetic procedure is analogous to that of 7a. The reaction of 2b
(109.0 mg, 0.080 mmol) with 1-pentyne (139.9 μL, 1.42 mmol) in
dichloromethane (20 mL) afforded a yellow solid, from which
[Cp*Ir(η4-2,4-nPr2C4H2SDmp)](BArF4) (7b) (96.4 mg, 0.058
mmol, 72% yield) was obtained as yellow crystals (an Et2O/
hexane solution was used). See above for the numbering of the
η4-2,4-R2C4H2S-Dmp ligand. 1H NMR (CDCl3): δ 7.69 (bs, 8H,
ArF), 7.61 (t, J=7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs, 4H,
ArF), 7.03, 7.01 (s, 2H, m-H of Mes) 7.01 (d, J=7.6 Hz, 1H, m-H
of SC6H3Mes2), 4.32 (s, 1H, H-C2 in SC4H2(C2H4CH3)2), 3.05
(s, 1H, H-C4 in SC4H2(C2H4CH3)2), 2.36, 1.92 (s, 6H,
o-CH3 of Mes), 2.02 (s, 6H, p-CH3 of Mes), 1.66 (s, 15H,
Synthesis of [Cp*Ir(SDmp)(CO)2](BArF4) (6b). (A) NMR
experiment: An NMR tube equipped with a J-Young valve
was charged with 2b (10.3 mg, 0.007 mmol) and CDCl3 (0.60
mL, with 1% Si(SiMe3)4 as the internal standard). After freeze-
pump-thaw cycles, 1 atm of CO was charged into the tube at
room temperature. The color of the solution immediately turned
pink. The 1H NMR spectrum revealed the quantitative forma-
tion of [Cp*Ir(SDmp)(CO)2](BArF4) (6b). The NMR signals of
6b were retained after three freeze-pump-thaw cycles followed
by purging with N2. (B) Preparative scale: A toluene (20 mL)
solution of 2b (101.9 mg, 0.066 mmol) was exposed to 1 atm of

Article
Organometallics, Vol. 29, No. 7, 2010 1769
Table 4. Crystal Data for [Cp*M(SDmp)](BArF4) (2a, M = Rh; 2b, M = Ir), [Cp*M(SDmp)(bpy)](BArF4) (3a, M = Rh; 3b, M = Ir),
[Cp*M(SDmp)(phen)](BArF4) (4a, M = Rh; 4b, M = Ir), [Cp*Ir(SDmp)(CNtBu)2](BArF4) (5b), [Cp*M(η4-2,4-nPr2C4H2SDmp)]-
(BArF4) (7a, M = Rh; 7b, M = Ir), and [Cp*M(η4-2,4-Ph2C4H2SDmp)](BArF4) (8a, M = Rh; 8b, M = Ir)
2a
2b
3a
empirical formula
fw
C
66H52RhSF24
B
C66H52IrSF24
1536.19
green, block
triclinic
P1 (No. 2)
13.265(3)
14.381(3)
17.235(3)
89.267(7)
87.527(7)
75.296(4)
3177.1(11)
2
1.606
22.509
55
total: 25 274
unique: 13 941
(Rint = 0.086)
13 941
830
16.80
B
C76H60N2RhSF24
1603.06
brown, block
triclinic
P1 (No. 2)
14.345(4)
15.473(4)
17.581(5)
102.956(2)
110.459(4)
91.609(3)
3538.7(18)
2
1.504
3.789
55
total: 27 948
unique: 15 475
(Rint = 0.036)
15 475
977
15.84
0.0627
0.1732
1.058
B
1446.87
green, block
triclinic
P1 (No. 2)
13.2119(16)
14.4067(17)
17.253(2)
89.116(4)
87.236(4)
75.225(3)
3171.6(7)
2
1.515
4.127
55
total: 26 045
unique: 13 941
(Rint = 0.032)
13 941
cryst color, habit
cryst syst
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z value
Dcalcd (g cm-3
)
μ(Mo KR) (cm-1
max 2θ (deg)
no. of reflns measd
)
no. observations (all reflns)
no. variables
refln/param ratio
R1 (I > 2.00σ(I))a
wR2 (all reflections)b
GOFc on F2
833
16.74
0.0486
0.1394
1.059
0.0631
0.1488
0.916
3b
4a
4b 1/2C6H14
3
empirical formula
fw
C76H60N2IrSF24
1692.37
B
C78H60N2RhF24SB
1627.08
C81H67N2IrF24SB
1759.49
cryst color, habit
cryst syst
space group
brown, block
triclinic
brown, block
triclinic
brown, block
triclinic
P1 (No. 2)
14.362(3)
15.485(3)
17.547(3)
103.1680(19)
110.4260(17)
91.3870(15)
3537.8(11)
2
1.589
20.304
55
total: 27818
unique: 15434
(Rint = 0.034)
15 434
P1 (No. 2)
14.0447(18)
16.641(2)
17.788(2)
70.042(9)
67.269(8)
77.022(11)
3583.7(8)
2
1.508
3.754
55
total: 28163
unique: 15655
(Rint = 0.017)
15 655
P1 (No. 2)
12.803(3)
14.759(3)
21.882(5)
75.953(6)
82.947(8)
72.827(7)
3826.6(14)
2
1.527
18.804
55
total: 30187
unique: 16745
(Rint = 0.056)
16 745
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z value
Dcalcd (g cm-3
)
μ(Mo KR) (cm-1
max 2θ (deg)
no. of reflns measd
)
no. observations (all reflns)
no variables
refln/param ratio
R1 (I > 2.00σ(I))a
wR2 (all reflections)b
GOFc on F2
941
16.40
0.0402
0.1043
1.030
962
16.27
0.0461
0.1293
1.027
959
17.46
0.0677
0.1726
1.063
5b
6b C6H5CH3
3
7a
7b
empirical formula
fw
C76H74N2IrSF24
1706.49
B
C75H60O2IrF24SB
1684.35
C76H68RhF24SB
1583.11
C76H68IrF24SB
1672.42
cryst color, habit
cryst syst
space group
yellow, block
triclinic
pink, block
triclinic
yellow, block
triclinic
yellow, block
triclinic
P1 (No. 2)
14.072(4)
14.753(4)
20.935(5)
98.802(2)
100.479(2)
113.803(3)
3784.3(16)
2
1.497
18.986
55
total: 31 073
unique: 16 636
P1 (No. 2)
12.391(4)
14.593(4)
20.903(6)
92.797(5)
102.433(7)
97.229(3)
3650.6(19)
2
1.532
19.684
55
total: 29 442
unique: 16 081
P1 (No. 2)
12.497(4)
15.449(4)
20.125(6)
81.748(9)
77.176(9)
86.299(10)
3747.2(18)
2
1.403
3.560
55
total: 30 825
unique: 16 482
P1 (No. 2)
12.5495(18)
15.480(2)
20.139(2)
81.869(4)
77.328(4)
86.001(4)
3775.6(9)
2
1.471
19.007
55
total: 30 852
unique: 16 610
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z value
Dcalcd (g cm-3
)
μ(Mo KR) (cm-1
max 2θ (deg)
no. of reflns measd
)

1770 Organometallics, Vol. 29, No. 7, 2010
Sakamoto et al.
Table 4. Continued
5b
76H74N2IrSF24
1706.49
6b C6H5CH3
3
7a
7b
empirical formula
fw
C
B
C75H60O2IrF24SB
1684.35
C76H68RhF24SB
1583.11
C76H68IrF24SB
1672.42
cryst color, habit
cryst syst
space group
yellow, block
triclinic
P1 (No. 2)
14.072(4)
14.753(4)
20.935(5)
pink, block
triclinic
P1 (No. 2)
12.391(4)
14.593(4)
yellow, block
triclinic
P1 (No. 2)
12.497(4)
15.449(4)
yellow, block
triclinic
P1 (No. 2)
12.5495(18)
15.480(2)
˚
a (A)
˚
b (A)
˚
c (A)
20.903(6)
20.125(6)
20.139(2)
Cp*), 1.26, 1.10 (m, 2H, SC4H2(C2H4CH3)2), 1.20, 0.90 (t, J =
7.0 Hz, 2H, SC4H2(C2H4CH3)2), 0.95, 0.81 (t, J = 7.2 Hz, 3H,
(s, ipso-C of Ph), 129.4, 127.9 (s, p-C of Ph), 129.3, 129.2 (s, o-C
of Ph), 128.9, 128.7 (s, m-C of Mes), 128.9 (q, JFC=32.4 Hz, m-C
of ArF), 124.6, 124.4 (s, m-C of Ph), 124.5 (q, JFC = 287.9 Hz,
CF3), 117.4 (s, p-C of ArF), 93.5 (s, C5(CH3)5), 85.4 (s, C3 in
SC4H2Ph2), 77.2 (s, C2 in SC4H2Ph2), 62.8 (s, C4 in SC4H2Ph2),
52.2 (s, C1 in SC4H2Ph2), 25.4, 20.8 (s, o-CH3 of Mes), 21.1 (s, p-
CH3 of Mes), 8.1 (s, C5(CH3)5). Anal. Calcd for C84H72SF24BIr:
C, 56.59; H, 3.71; S, 1.84. Found: C, 56.69; H, 3.90; S, 1.75.
X-ray Structural Determination. Crystal data and refinement
parameters for complexes 2a, 2b, 3a, 3b, 4a, 4b, 5b, 6b, 7a, and 7b
are summarized in Table 4. Single crystals were coated with oil
(immersion oil, type B: code 1248, Cargille Laboratories, Inc.)
and mounted on loops. Diffraction data were collected at
-100 °C under a cold nitrogen stream on a Rigaku AFC8
equipped with a Saturn CCD detector (2a, 5b, 6b, 7a, 7b) or a
Rigaku AFC8 equipped with a Mercury CCD detector (2b, 3a,
3b, 4a, 4b) equipped with a graphite-monochromatized Mo KR
SC4H2(C2H4CH3)2). 13C{1H} NMR (CDCl3): δ 161.7 (q, JBC
=
49.7 Hz, ipso-C of ArF), 146.5, 140.2, 139.1, 136.3, 136.2, 134.3
(s, Ar), 134.8 (s, o-C of ArF), 133.1 (s, p-C of SC6H3Mes2), 131.7
(s, m-C of SC6H3Mes2), 128.8 (q, JFC=31.5 Hz, m-C of ArF),
128.7, 128.6 (s, m-C of Mes), 124.5 (q, JFC =271.9 Hz, CF3),
117.4 (s, p-C of ArF), 92.9 (s, C5(CH3)5), 89.3 (s, C3 in SC4H2-
(C2H4CH3)2), 77.0 (s, C2 in SC4H2(C2H4CH3)2), 66.8 (s, C4 in
SC4H2(C2H4CH3)2), 57.0 (s, C1 in SC4H2(C2H4CH3)2), 29.5,
29.2, 21.9, 20.7 (s, SC4H2(C2H4CH3)2), 21.3 (s, p-CH3 of Mes),
21.0, 20.9 (s, o-CH3 of Mes), 13.9, 13.4 (s, SC4H2(C2H4(CH3)2),
9.2 (s, C5(CH3)5). Anal. Calcd for C78H76SF24BIr: C, 54.58; H,
4.10; S, 1.92. Found: C, 54.96; H, 4.15; S, 1.92.
Synthesis of [Cp*Rh(η4-2,4-Ph2C4H2SDmp)](BArF4) (7c).
The synthetic procedure is analogous to that of 7a. The reaction
of 2a (101.6 mg, 0.070 mmol) with phenylacetylene (154.2 μL,
0.140 mmol) in dichloromethane (20 mL) gave a yellow solid,
from which [Cp*Rh(η4-2,4-Ph2C4H2SDmp)](BArF4) (7c) (96.4
mg, 0.057 mmol, 82% yield) was obtained as yellow crystals. See
above for the numbering of the η4-2,4-R2C4H2SDmp ligand. 1H
NMR (CDCl3): δ 7.70 (bs, 8H, ArF), 7.60 (t, J = 7.6 Hz, 1H, p-H
of SC6H3Mes2), 7.51 (bs, 4H, ArF), 7.41, 7.28 (t, J = 7.7 Hz, 2H,
m-H of Ph), 7.36, 7.22 (m, 1H, p-H of Ph), 7.11 (d, J = 7.6 Hz,
2H, m-H of SC6H3Mes2), 7.08, 6.79 (d, J = 7.7 Hz, 2H, o-H of
Ph), 6.91, 6.81 (s, 2H, m-H of Mes), 5.36 (s, 1H, H-C2 in
SC4H2Ph2), 3.67 (s, 1H, H-C4 in SC4H2Ph2), 2.36 (s, 6H, p-CH3
of Mes), 1.92, 1.62 (s, 6H, o-CH3 of Mes), 1.11 (s, 15H, Cp*).
13C{1H} NMR (CDCl3): δ 161.7 (q, JBC = 50.0 Hz, ipso-C of
ArF), 142.2, 139.7, 138.8, 136.4, 135.9 (s, Ar), 134.8 (s, o-C of
ArF), 134.1 (s, p-C of SC6H3Mes2), 131.5 (s, m-C of SC6H3-
Mes2), 130.1, 129.9 (s, ipso-C of Ph), 129.7, 128.0 (s, p-C of Ph),
129.4, 129.3 (s, o-C of Ph), 129.0, 128.6 (s, m-C of Mes), 128.8 (q,
˚
source (λ = 0.71070 A). Six preliminary data frames were
measured at 0.5° ω increments, to assess the crystal quality
and preliminary unit cell parameters. The intensity images were
also measured at 0.5° intervals of ω. The frame data were
integrated using the CrystalClear program package, and the
data sets were corrected for absorption using the REQAB
program. The calculations were performed with the Crystal-
Structure program package. Structures were solved by Patter-
son methods (2a, 2b, 4a, 4b, 5b, 6b, 7a, 7b) or direct methods (3a,
3b) and refined by full-matrix least-squares procedures on F2.
Anisotropic refinement was applied to all non-hydrogen atoms
except for disordered CF3 groups of BArF4 anions and crystal
solvents. All of the hydrogen atoms except for the 2,4-nPr2-
C4H2SDmp group in 7a and 7b were placed at calculated
positions. The hydrogen atoms in the 2,4-nPr2C4H2SDmp group
in 7a and 7b were located in each Fourier map and were refined
isotropically. The R value for 7a is relatively high (R1 = 9.20%)
owing to the disorders found for the propyl groups of the
J
FC = 33.3 Hz, m-C of ArF), 124.6, 124.4 (s, m-C of Ph), 124.5
(q, JFC = 272.7 Hz, CF3), 117.4 (s, p-C of ArF), 98.7 (d, JRhC
=
2,4-nPr2C4H2SDmp ligand and the CF3 groups of the BArF
5.8 Hz, C5(CH3)5), 95.3 (d, JRhC = 6.4 Hz, C3 in SC4H2Ph2),
71.1 (d, JRhC = 6.4 Hz, C2 in SC4H2Ph2), 63.0 (d, JRhC = 13.0
Hz, C1 in SC4H2Ph2), 40.0 (d, JRhC = 14.5 Hz, C4 in SC4H2-
Ph2), 21.4, 21.0 (s, o-CH3 of Mes), 20.8 (s, p-CH3 of Mes), 8.2 (s,
C5(CH3)5). Anal. Calcd for C84H72SF24BRh: C, 59.94; H, 4.31;
S, 1.90. Found: C, 59.91; H, 3.93; S, 1.97.
4
anion. The propyl groups of the 2,4-nPr2C4H2SDmp ligand in 7a
and 7b were disordered over two positions with occupancy
factors of 50:50. Two CF3 groups in 2a, 3a, 3b, 5b, and 7b, three
CF3 groups in 2b, one CF3 group in 4a and 7a, and five CF3
groups in 4b and 6b were disordered over two positions with
occupancy factors of 50:50. One of the CF3 groups in 4b and 7b
and three CF3 groups in 7a were disordered over two positions
with occupancy factors of 70:30. One of the CF3 groups in 5b,
two CF3 groups in 6b and 7a, and three CF3 groups in 7b were
disordered over three positions. The atomic coordinates are
available as a CIF file.
Synthesis of [Cp*Ir(η4-2,4-Ph2C4H2SDmp)](BArF4) (7d). The
synthetic procedure is analogous to that of 7a. The reaction of 2b
(115.5 mg, 0.075 mmol) with phenylacetylene (165.2 μL, 1.50
mmol) in dichloromethane (20 mL) afforded a yellow solid,
from which [Cp*Ir(η4-2,4-Ph2C4H2SDmp)](BArF4) (7d) (105.9
mg, 0.060 mmol, 79% yield) was obtained as yellow crystals (a
THF/hexane solution was used). See above for the numbering of
the η4-2,4-R2C4H2SDmp ligand. 1H NMR (CDCl3): δ 7.69 (bs,
8H, ArF), 7.63 (t, J = 7.6 Hz, 1H, p-H of SC6H3Mes2), 7.51 (bs,
4H, ArF), 7.39, 7.26 (t, J = 8.1 Hz, 2H, m-H of Ph), 7.34, 7.21
(m, 1H, p-H of Ph), 7.13 (d, J=7.6 Hz, 2H, m-H of SC6H3-
Mes2), 7.05, 6.75 (d, J = 8.0 Hz, 2H, o-H of Ph), 6.89, 6.86 (s,
2H, m-H of Mes), 5.23 (s, 1H, H-C2 in SC4H2Ph2), 3.93 (s, 1H,
H-C4 in SC4H2Ph2), 2.36 (s, 6H, p-CH3 of Mes), 1.92, 1.62
(s, 6H, o-CH3 of Mes), 1.21 (s, 15H, Cp*). 13C{1H} NMR
(CDCl3): δ 161.7 (q, JBC = 50.7 Hz, ipso-C of ArF), 143.8,
142.1, 138.9, 136.4, 136.0 (s, Ar), 134.8 (s, o-C of ArF), 133.9 (s,
p-C of SC6H3Mes2), 131.7 (s, m-C of SC6H3Mes2), 131.2, 130.5
Supporting Information Available: An X-ray crystallographic
information file (CIF) is available free of charge via the Internet
at http://pubs.acs.org.
Acknowledgment. This research was financially sup-
ported by a Grant-in-Aid for Scientific Research (Nos.
18GS0207, 18064009, and 20613004) from the Ministry
of Education, Culture, Sports, Science, and Technology,
Japan. We thank Prof. Roger E. Cramer at the University
of Hawaii for fruitful discussions and for careful reading
of the manuscript.