Synthesis, structure, spectroscopy, and reactivity of half-open rhodocenium and iridocenium with oxodienyl ligands

Article abstract of DOI:10.1021/om020400q

The synthesis, structure, spectroscopy, and reactivity of half-open rhodocenium and iridocenium with oxodienyl ligands were investigated. X-ray diffraction was used for the analysis. Exo-anti and exo-syn preferences were established for all synthesized rh

Full text of DOI:10.1021/om020400q

4696
Organometallics 2002, 21, 4696-4710
Syn th esis, Str u ctu r e, Sp ectr oscop y, a n d Rea ctivity of
Ha lf-Op en Rh od ocen iu m a n d Ir id ocen iu m w ith
Oxod ien yl Liga n d s
Irma Idalia Rangel Salas and M. Angeles Paz-Sandoval*
Departamento de Quı´mica, Centro de Investigacio´n y de Estudios Avanzados del IPN,
Apartado Postal 14-740, Me´xico 07000, D.F., Me´xico
Heinrich No¨th
Department Chemie, Universita¨t Mu¨nchen, Butenandstrasse 5-13 (Haus D),
81377, Mu¨nchen, Germany
Received J une 19, 2002
The syntheses of the oxopentadienyl complex [Cp*Rh(η5-CH2C(Me)CHC(Me)O)][BF4] (6)
and the iridaoxabenzene [Cp*IrAg2(µ2-OPF2O)2(1,5-η-CHC(CMe3)CHC(CMe3)O)] (9) are
reported. Compound 9 is an organometallic polymer, formed in competition with complex
[(Cp*Ir)2(µ2-OPF2O)3][PF6] (8). Treatment of [Cp*MCl2]2 (M ) Rh, Ir) with lithium 2-methyl-
4-oxopentadienide produces Cp*M(Cl)[η3-CH2C(Me)CHC(Me)(O)] (M ) Ir, 7; Rh, 10). 1H and
13C NMR, as well as IR spectra, indicate that the ligand acts as an η3-oxodienyl group with
an exo-syn conformation. The addition of phosphines, PR3 (R ) Ph, Me or PR3 ) PHPh2), in
acetone to compound [Cp*Ir(η5-CH2C(Me)CHC(Me)O)][PF6] (1) led to the formation of isomers
[Cp*Ir(1,5-η-CH2C(Me)CHC(Me)O)(L)][PF6] [L ) PMe3, 11; PPh3, 15] and [Cp*Ir(η3-CH2C-
(Me)CHC(Me)O)(L)][PF6] [L ) PMe3, 12; PHPh2, 14; PPh3, 16]. The 1,5-η and the η3 isomers
are the kinetic and thermodynamic products, respectively. The addition of phosphines PR3
(R ) Me, Ph) in methylene chloride to compound 6 led to the formation of compounds [Cp*Rh-
(η3-CH2C(Me)CHC(Me)O)(L)][BF4] [L ) PMe3, 18; PPh3, 20]. Compounds 18, 20, and [Cp*Rh-
(η3-CH2C(Me)CHC(Me)O)(PHPh2)][OTf] (21) can also be obtained by adding the corresponding
phosphine to compound 10, followed by the addition of AgOTf. The addition at room
temperature of acetonitrile to compound 1 led to the formation of [Cp*Ir(η3-CH2C(Me)CHC-
(Me)O)(NCMe)][PF6] (22), with an exo-anti conformation of the oxodienyl ligand. Facile
dissociation of MeCN became evident. The exo-anti isomer structure of 22 has unequivocally
been established by an X-ray diffraction study. The analogous rhodium exo-syn isomer
[Cp*Rh(η3-CH2C(Me)CHC(Me)O)(NCMe)][BF4] (23) has been established by 1H and 13C NMR
spectroscopy. Exo-anti and exo-syn preferences have been established for all synthesized
rhodium and iridium compounds. Compounds 1 and 6 did not suffer oxidative addition with
SnCl4 and I2. With I2 the bridged iodine compounds [(Cp*M)2(µ2-I)3][X] (M ) Ir, X ) PF6,
25; M ) Rh, X ) BF4, 26) were obtained. Crystal structures for iridium compounds 1, 9, 22,
and 25 and rhodium compounds 6, 10, 18, and [Cp*Rh(η3-CH2C(Me)CHC(Me)O)(H2O)][BF4]
(24) are described.
In tr od u ction
was demonstrated when compound 1 was prepared in
the presence of mesityl oxide and 2, in better yields
(Scheme 1).
Interest in the chemistry of cationic half-open rhodo-
cene- or iridium-containing oxodienyl ligands has re-
ceived additional impetus after the study of the neutral
half-open ruthenocene analogous complexes.1
Compound 1 can be slowly converted into the isomer
[Cp*Ir(η5-CH2C(Me)CHC(OH)CH2)][PF6] (3) in the pres-
ence of acid. There was no evidence for the formation
of a rhodium analogue to compound 1. In contrast to
the behavior of iridium compound 2, when the rhodium
Maitlis and co-workers2 were the first to describe
[Cp*Ir(η5-CH2C(Me)CHC(Me)O)][PF6] (1) from a seren-
dipitous reaction of the cationic [Cp*Ir(Me2CO)3]2+ (2)3
with 4-methylpent-3-en-2-one (mesityl oxide), which was
formed in situ by a catalyzed aldol condensation. This
acetone solvent complex [Cp*Rh(Me2CO)3]2+, 4, was
-
heated, the PF6- ion was partially solvolyzed to PO2F2
,
which coordinated in a bridging manner to two Cp*Rh
units, giving a crystalline compound, [(Cp*Rh)2(µ2-
OPF2O)3][PF6] (5).4
* To whom correspondence should be addressed: E-mail: mpaz@
mail.cinvestav.mx.
(1) Navarro, M. E.; J ua´rez Saavedra P.; Cervantes Va´squez, M.; Paz-
Sandoval, M. A.; Arif, A. M.; Ernst, R. D. Organometallics 2002, 21,
592.
(2) White, C.; Thompson, S. J .; Maitlis, P. M. J . Organomet. Chem.
1977, 134, 319.
(3) (a) White, C.; Thompson, S. J .; Maitlis, P. M. J . Chem. Soc.,
Dalton Trans. 1977, 1654. (b) White, C.; Yates, A.; Maitlis, P. M. Inorg.
Synth. 1992, 29, 228.
10.1021/om020400q CCC: $22.00 © 2002 American Chemical Society
Publication on Web 10/04/2002

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4697
Specifically, the anionic oxapentadienide17,18 reagents
as building blocks have been reported for iridium. The
formation of (1,2,5-η- or η3-5-oxopentadienyl)iridium
complexes,17 their protonation, or the corresponding
protonation of (2,5-η-oxairidacycles) gives iridafuran
complexes as the thermodynamic products.18
Sch em e 1
As mentioned before, isoelectronic half-open ru-
thenocenes of the type Cp*Ru(η5-oxopentadienyl) have
been prepared and their reactivity has been explored
toward oxidative addition or ligand addition reactions.1
The present studies center on the synthesis and
reactivity of [Cp*M(η5-CH2C(Me)CHC(Me)O)][X] [M )
Ir, X ) PF6 (1); M ) Rh, X ) BF4 (6)] and [Cp*IrAg2-
(µ2-OPF2O)2(1,5-η-CHC(CMe3)CHC(CMe3)O)] (9). Com-
pounds 1 and 6 and their reactions have been of special
interest as part of an effort to understand the reactivity
of the oxodienyl ligand. In particular, we would like to
compare with neutral isoelectronic Cp*Ru[η5-CH2C(R)-
CHC(R)O] [R ) Me, CMe3] complexes, which have
already been studied in detail.1
In the past, a few acyclic 1-oxopentadienyl transition
metal compounds were described as unexpected prod-
ucts from various chemical reactions, affording com-
Resu lts a n d Discu ssion
5
plexes, such as [Pd(µ-Cl)(η3-CH(R1)CHCH(R2)]2 (R1 )
Syn th esis a n d Sp ectr oscop y of Oxod ien yl Com -
pou n ds. The iridium-oxodienyl complex [Cp*Ir(η5-CH2C-
(R)CHC(R)O)][PF6] [R ) Me, 1] was most conveniently
prepared by replacement of the solvent in the labile tris-
acetone derivative 2 by mesityl oxide in 68% (64)2 yield.
This salt showed high solubility in chlorinated sol-
vents, acetone or nitromethane, but little in organic
solvents less polar than chloroform. While compound 1
is obtained pure, analogue compounds with R ) Ph or
t-Bu failed to give the η5-oxopentadienyl half-open
sandwich derivatives. Compound 1 was characterized
H, R2 ) CO2Et; R1 ) Me, R2 ) CO2Et); Pd(Cl)(η3-CH2C-
(Me)CHC(Me)O)(PPh3),6 Mn[η5-CH(R1)C(R2)CHC(R3)O]-
(CO)3 (R1 ) Ph, R2 ) Me, R3 ) CH2Ph;7 R1 ) Me, R2 )
H, R3 ) Ph;8 R1 ) Et, R2 ) H, R3 ) Ph9), and Re(η5-
CH2CHCHCHO)(CO)(PPh3)2.10 More recently, conve-
nient syntheses of oxodienyl complexes of several tran-
sition elements have been reported; some examples are
CpFe(L)(η3-CH2CHCHCOMe)[L )CO,PMe3,P(OMe)3],11
CpRu(CO)(η3-CH2CHCHCHO),12 Mn(η5-CH2CHCHCOR)-
(CO)3 (R ) OMe, Me), and derivatives, such as Mn(η3-
CH2CHCHCOR)(CO)3(L) [L ) MeCN, Me2CO, THF, CO]
or their phosphine complexes Mn(η5-CH2CHCHCOR)-
(CO)2(PR3) and Mn(η3-CH2CHCHCOR)(CO)3(PR3) (PR3
) PMe3, PPh3).13 The trimethylsilyloxy-buta-1,3-dienes
Me3SiOCHdCR1CHdCHR2 [R1 ) R2 ) H; R1 ) Me, R2
) H; R1 ) H, R2 ) Me] coordinate to the labile
acetonitrile complexes [(η5-L)Mo(NCMe)2(CO)2][BF4] (L
) C9H7 or Cp*) followed by a rapid desilylation, afford-
ing the corresponding oxodienyl derivatives (η5-L)Mo-
(η3-CR3R2CHCR1CHO)(CO)2 (R3 ) H, Me) as a mixture
of isomers.14 In 1991, the first homoleptic open ru-
thenocenes with non-hydrocarbon ligands were pub-
lished,15 and a systematic exploration of the synthesis
of (heterodienyl)metal complexes has been carried out
by Bleeke, using halo-metal-phosphine compounds.16
1
by its H, 13C, and 31P NMR spectra (Tables 1 and 2),
and the X-ray crystal structure determination was also
carried out (Figure 1).
Attempts to use AgPF6 in the reaction of [Cp*IrCl2]2
and the lithium 2,4-diphenyl-4-oxobutadienide complex
were unsuccessful.
Compound 1 can also be obtained at room tempera-
ture from Cp*Ir(Cl)(η3-CH2C(Me)CHC(Me)O) (7) in the
presence of AgPF6 within 30 min. However, it is always
isolated along with the isomeric hydroxypentadienyl
complex [Cp*Ir(η5-CH2C(Me)CHC(OH)CH2)][PF6] (3),
which is the corresponding enol form of compound 1
(Scheme 2). There was no evidence of formation of
compound [(Cp*Ir)2(µ2-OPF2O)3][PF6] (8) (vide infra).2
An analogous synthetic procedure, as described for
compound 1, was followed using compound 2 and the
corresponding 2,2,5,6,6-pentamethyl-4-hepten-3-one. In-
stead of the oxopentadienyl analogue, a novel polymeric
iridaoxabenzene complex [(Cp*IrAg2(µ2-OPF2O)2)(1,5-η-
(4) Thompson, S. J .; Bailey, P. M.; White, C.; Maitlis, P. M. Angew.
Chem., Int. Ed. Engl. 1976, 15, 490.
(5) Tsuji, J .; Imamura, S.; Kiji, J . J . Am. Chem. Soc. 1964, 86, 4491.
(6) Parshall, G. W.; Wilkinson, G. Inorg. Chem. 1962, 1, 896.
(7) Bennett, R. L.; Bruce, M. I. Aust. J . Chem. 1975, 28, 1141.
(8) Bannister, W. D.; Green, M.; Haszeldine, R. N. J . Chem. Soc.
(A) 1966, 194.
(9) Green, M.; Hancock, R. I. J . Chem. Soc. (A) 1968, 109.
(10) Baudry, D.; Daran, J .-C.; Dromzee, Y.; Ephritikhine, M.; Felkin,
H.; J eannin,Y.; Zakrzewski, J . J . Chem. Soc., Chem. Commun. 1983,
813.
(11) Cheng, M.-H.; Wu, Y.-J .; Wang, S. L.; Liu, R. S. J . Organomet.
Chem. 1989, 373, 119.
(12) Benyunes, S. A.; Day, J . P.; Green, M.; Al-Saadoon, A. W.;
Waring, T. L. Angew. Chem., Int. Ed. Engl. 1990, 29, 1416.
(13) Cheng, M.-H.; Cheng, C.-Y.; Wang, S.-L.; Peng, S.-M.; Liu, R.-
S. Organometallics 1990, 9, 1853.
(14) Benyunes, S. A.; Binelli, A.; Green, M.; Grimshire, M. J . J .
Chem. Soc., Dalton Trans. 1991, 895.
(16) (a) Bleeke, J . R.; Luaders, S. T.; Robinson, K. D. Organome-
tallics 1994, 13, 1592. (b) Bleeke, J . R.; Rohde, A. M.; Robinson, K. D.
Organometallics 1995, 14, 1674. (c) Bleeke, J . R.; Ortwerth, M. F.;
Chiang, M. Y. Organometallics 1992, 11, 2740. (d) Bleeke, J . R.;
Ortwerth, M. F.; Rohde, A. M. Organometallics 1995, 14, 2813.
(17) (a) Bleeke, J . R.; Haile, T.; New, P. R.; Chiang, M. Y. Organo-
metallics 1993, 12, 517. (b) Bleeke, J . R.; Haile, T.; Chiang, M. Y.
Organometallics 1991, 10, 19.
(18) Bleeke, J . R.; New, P. R.; Blanchard, J . M. B.; Haile, T.; Beatty,
A. M. Organometallics 1995, 14, 5127.
(19) (a) Bleeke, J . R.; Blanchard, J . M. B. J . Am. Chem. Soc. 1997,
119, 5443. (b) Bleeke, J . R.; Blanchard, J . M. B.; Donnay, E. Organo-
metallics 2001, 20, 324, and references therein.
(15) Schmidt T.; Goddard, R. J . Chem. Soc., Chem. Commun. 1991,
1427.
(20) Chen, J .; Daniels, L. M.; Angelici, R. J . J . Am. Chem. Soc. 1990,
112, 199.

4698 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Ta ble 1. 1H a n d 31P NMR Da ta a for Com p ou n d s 1, 6, 7, 9-12, 14-16, a n d 18-23
compound
H1 anti
3.09, s
H1 syn
4.15, s
H3
6.65, s
H(C5)
H(C6)
Cp*
L
31P
1
2.03, s,
2.44, s,
2.02, s
-143.7 PF6
J PF ) 714
(3.08)b
3.52, s
(4.12)
4.38, s
(6.65)
6.13, s
(2.00)
2.01, s
(2.41)
2.41, s
(2.00)
2.02, s
6-BF 4
6-P F 6
3.50, s
2.83, s
4.02, s
6.29, s
1.95, s
2.39, s
1.94, s
-143.5 PF6
J PF ) 715
7
3.21, s
9.61, d
2.5 Hz
3.57, s
6.83, d
2.5 Hz
2.00, s
1.27, s
2.17, s
1.39, s
1.64, s
2.05, s
9c
-13.1 PF2O2
J PF ) 949
10
11
3.20, s
n.a.
3.33, s
3.12, td
3.61, s
6.13, s
2.12, s
1.99, s
2.15, s
2.10, s
1.60, s
1.82, d
J ) 1.9
1.65, d
J ) 9.9
-44.3 PMe3
-143.2 PF6
J ) 16.5
J ≈ 2.0
12
2.74-2.81, m
2.74-2.81, m
2.74-2.81, m
2.04, s
1.67, s
2.43, s
2.28, s
1.81, d
J ) 1.5
1.76, d
J ) 2.2
1.63, d
-36.4 PMe3
-143.2 PF6
8.8, d
J PH ) 417
PHPh2
J ) 10.3
7.2-7.7,
6.49, d
14
exo-a n ti
3.10, d
J ) 19.3
3.52, s, br
4.82, s
J PH ) 421
-143.8PF6
-5.9 PHPh2
-143.8 PF6
14
exo-syn
2.08, d
J ) 10.6
3.05, d
J ) 2
2.26, d
J ) 15.9
1.86, s
1.95, s
2.45, s
2.02, s
1.72, d
J ) 2.9
7.07, d
J ) 407
7.3-7.7, m
7.3-7.7
15
2.90, d
J ) 15.8
4.32, td
J ) 16.1
J ) 1.8
3.06, d
J ) 1.6
2.86, d
J ≈ 2.0
5.84, s
1.35, d
J ) 2.0
-12.9 PPh3
-143.1 PF6
16
18
2.16, d
J ) 12.6
2.18, d
2.53, d
J ) 16.6
2.60, d
1.99, s
2.09, s
2.40, s
2.37, s
1.51, d
J ) 2.2
1.79, d
J ) 3.3
7.3-7.6
12.4PPh3
-143.1 PF6
3.05, d
J ) 148.8
PMe3
1.61, dd
J ) 9.9, 0.7
J ) 15.0
J ) 11.7
19
20
21
2.49, d
J ) 12.5
3.29, m
J ) 15.4
5.98, s
2.09, s
2.01, s
1.93, s
2.16, s
2.31, s
2.32, s
1.32, d
J ) 3.3
7.3-7.7
40.9, d
J ) 158.8
PPh3
48.4, d
J ) 153.8
PPh3
27.9, d
J ) 154
PHPh2
2.16, d
J ) 14.0
3.41, s, br
2.37, d
J ) 12.9
1.48, d
J ) 3.5
7.3-7.6
2.09, d
J ) 11.4
3.16, s, br
2.10, d
J ) 16.8
1.68, d
J ) 4.5
7.2-7.7
7.08, d
J ) 390
2.67, s
1.97, s
22 exo-a n ti
22
exo-syn
23
3.19, s
2.46, s, br
3.76, s
3.37, d
J ) 1.2
3.44, s
4.95, s
3.32, s
1.94, s
2.06, s
2.01, s
2.22, s
1.89, s
1.70, s
2.72, s
3.23, s
2.04, s
2.09, s
1.56, s
1.90, s, br
a
b
c
In CDCl3. δ values are in ppm and J values in hertz. For numbering, see oxodienyl ligand in any crystal structure figure. Ref 2. In
CD3CN.
CHC(CMe3)CHC(CMe3)O)] (9) was isolated in 34-65%
and the establishment of a ring current in the metal-
laoxabenzene compound 9. Similar chemical shifts have
been reported for the iridapyrylium complex [{IrCHC-
(Me)CHC(Me)O}(PEt3)3][BF4],19 other iridathiabenzenes
Cp*Ir[SC(Me)CHCHC(Me)],20 [{IrSCHCHCHCH}(PPh2-
CH2)3CCH3][BF4],21 and several related examples of
metallathiabenzenes,22 e.g., Cp*Rh[SCHCHCHCH].23
The single Cp* signal at δ ) 2.02 is unexpectedly broad
(ν1/2 ) 11.4 Hz). The 13C{1H} NMR spectrum of the ring
carbons shows resonances at δ(CD3CN) ) 189.9 (C4),
101.5 (C3), 171.4 (C2), 140.7 (C1, br, ν1/2 ) ∼25 Hz),
while those for the iridapyrylium compound [{IrCHC-
(Me)CHC(Me)O}(PEt3)3]+ are at δ(CD2Cl2) ) 170.7 (C4),
112.2 (C3), 147.3 (C2), and 162.2 (C1).19b The 19F and
31P NMR (δ ) 185.7, d, 950 Hz and -16.2, t, 950 Hz,
yield, depending on the experimental conditions (see
Experimental Section). Compound 9 is an organome-
tallic polymer, formed in competition with complex 8
(Scheme 3).
The reaction of 2 and the corresponding ketone
required 15-30 min at 50 °C, leading to the precipita-
tion of compound 8 in 35-66% yield. From the orange
mother liquor, red crystals of 9 were isolated after 3-5
h at room temperature. Yields for compounds 8 and 9
are quite time dependent. After 15 min at 50 °C,
compound 8 can be isolated in 66% yield. However,
when the reaction was performed for 30 min at the same
temperature, 9 is obtained in ∼65% yield. Longer
reaction times do not improve the yield of compound 9.
The solid state structure of the polymeric compound 9
(Figure 2) is described below in the crystal structure
(21) (a) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Frediani,
P.; Herrera, V.; Sa´nchez-Delgado, R. A. J . Am. Chem. Soc. 1993, 115,
2731. (b) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Moneti, S.;
Herrera, V.; Sa´nchez-Delgado, R. A. J . Am. Chem. Soc. 1994, 116, 4370.
(22) Bleeke, J . R. Chem. Rev. 2001, 101, 1205, and references
therein.
1
section, and examination of the H NMR spectrum of
compound 9 revealed the presence, in solution, of two
signals at high frequency, as doublets at δ ) 9.61, 4J H-H
4
) 2.5 Hz, and δ ) 6.81, J H-H ) 2.5 Hz. This shifting
(23) Chin, R. M.; J ones, W. D. Angew. Chem., Int. Ed. Engl. 1992,
31, 357.
indicates metal orbital participation in ring π-bonding

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4699
Ta ble 2. 13C NMR Da ta a for Com p ou n d s 1, 6, 7, 9-12, 14-16, a n d 18-23
compound
C1
C2
C3
C4
C5
C6
MeCp*
CCp*
L
1
59.9
111.9
86.3
158.7
(157.2)
171.4
22.9
(23.2)
24.2
21.6
(21.8)
22.7
8.9
(9.2)
9.6
96.6
(60.3)b
(111.7)
(86.2)
(96.6)
6
BF 4
72.3, d
J RhC ) 9.1
121.5, d
J RhC ) 5.9
85.2, d
J RhC ) 4.1
102.3,d
J RhC ) 7.9
102.4, d
102.4, d
J RhC ) 7.9
93.1
P F 6
72.4, d
J RhC ) 9.1
49.6
121.6, d
J RhC ) 5.9
97.4
85.1, d
J RhC ) 4.1
59.5
172.1
24.5
22.9
9.8
7
9
203.6
189.8
31.2
40.9
31.3
31.3
18.7
38.7
28.3
18.7
8.1
9.6
140.7
171.4
101.5
92.9
10
11
12
63.8, d
J RhC ) 9.2
9.4, d
J PC ) 8.5
37.4, d
J PC) 3.8
43.0
111.8 d,
J RhC ) 6.1
167.0
67.9, d
202.4
199.2
202.8
204.4
8.6
9.9
9.0
9.3
98.6, d
J RhC ) 6.9
98.3
J RhC ) 8.4
121.3
32.6
32.3
32.6
27.5
17.8
22.6
17.5, d
J PC) 40.2
16.2, d
J PC) 41.2
134.8,
132.8,
132.1,
129.3
92.5, d
J PC ) 3.0
93.3
46.2, d
98.5
J PC ) 2.6
14
exo-a n ti
49.2,d
99.5, d
J PC ) 2.0
J PC ) 4.2
14
37.4
94.2
51.0
202.9
202.6
203.0
32.1
31.3
33.0
17.3
30.9
17.4
8.3
9.5
8.6
98.6
93.4
99.7
134.6
exo-syn
133.6
132.5
129.8
15
16
10.9, d
J PC ) 6.9
179.7
124.3
134.0,
131.3,
128.8,
128.3
39.4,d
J PC ) 3.3
96.1, d
J PC ) 2.7
48.8,d
J PC ) 2.6
135.5,
134.3,
132.4,
129.6,
16.0, d
J PC ) 33.1
134.9
18
19
52.0, d
106.8
177.6
57.0, d
200.7
202.9
31.8
30.1
18.5
29.9
9.1
9.0
102.7, d
J RhC ) 11.5
J
RhC ) 9.2
J RhC ) 4.7
25.8, dd
123.1
99.5, d
J RhC ) 23.6
J PC ) 9.5
J RhC ) 5.7
131.4
129.4
128.6
20
21
54.4, d
J RhC ) 10.8
109.9
60.0, d
J RhC ) 10.7
201.2
201.5
32.3
32.1
18.0
18.4
9.0
8.9
104.1, d
J RhC ) 5.3
134.7,
132.2
129.2
128.5
51.8, dd
J RhC ) 9.6,
J PC ) 4.8
107.8, dd
J RhC ) 4.7
J PC ) 2.3
62.1, d
J RhC ) 8.9
103.3, dd
J RhC ) 5.0,
J PC )1.5
134.7
133.4
132.3
129.9
22
exo-a n ti
23
50.3
99.7
59.0
201.6
201.4
30.6
31.5
23.4
18.1
9.1
8.5
95.9
8.2
116.5
63.6, d
J RhC ) 9.3
114.7, d
J RhC ) 5.2
67.2, d
J RhC ) 8.3
100.7, d
J RhC ) 6.2
9.6,
116.7
a
In CDCl3. δ values are in ppm and J values in hertz. For numbering, see oxodienyl ligand in any crystal structure figure. bRef 2. c In
CD3CN.
Sch em e 2
respectively) showed the corresponding signals for a
POF2O ligand.
(Me)CHC(Me)(O)] (M ) Ir, 7; Rh, 10) in ∼20 and 75%
yield, respectively (Scheme 2). Compounds 7 and 10 can
be recrystallized from diethyl ether/pentane, giving
Treatment of [Cp*MCl2]2 (M ) Rh, Ir) with lithium
2-methyl-4-oxopentadienide produces Cp*M(Cl)[η3-CH2C-
brick-red and yellow crystals. According to H and 13C
1

4700 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Sch em e 3
F igu r e 2. Structure of [Cp*IrAg2{µ2-OPF2O)2{1,5-η-CHC-
(CMe3)CHC(CMe3)O}] (9). tert-Butyl groups are omitted for
clarity.
In solution and in the solid state, the oxodienyl ligand
in compound 10 has the exo-syn conformation. The high
stability of both oxodienyl ligand conformers in solution
1
was confirmed by an H NMR experiment in which the
F igu r e 1. Structure of [Cp*Ir{η5-CH2C(Me)CHC(Me)O}]-
[PF6] (1).
samples in CDCl3 were heated at 50 °C for 10 and 5
days; there was no evidence for rearrangement of the
ligands in 7 and 10, respectively, suggesting that these
isomers are the thermodynamic products (vide infra).
The ν(CO) absorption of the unbound carbonyl group of
7 and 10 is observed at 1658 and 1654 cm-1, respec-
tively.
Marked differences in the chemical shift allow the exo
and endo isomers to be distinguished for many metal
compounds.25 However, in the case of rhodium and
iridium there is scarce information in the literature,
which was not helpful for the assignment of the pre-
ferred isomer, when only one is present.
Similar trends in chemical shifts have been observed
for complexes 7 and 10 and the analogous Cp*M(η3-
allyl)X [M ) Rh, X ) I;26 M ) Ir, X ) Br;27 M ) Rh, Ir,
X ) Cl28,29]. Only the exo isomer could be detected for
the allylic compounds, as was observed for the oxodienyl
derivatives. This is probably because steric factors favor
NMR of both species, as well as GOESY experiments,
the oxodienyl ligand in complexes 7 and 10 is W-shaped.
The latter compound presents the exo-syn conformation
for the oxopentadienyl ligand in the solid state, as
determined by X-ray diffraction studies (Figure 3).
Compounds 7 and 10 are quite soluble in diethyl
ether, chloroform, or methylene chloride. As described
1
above, their H and 13C NMR, as well as the IR spectra,
indicate that the ligand adopts an η3-oxodienyl confor-
mation. The syn conformations were indicated by the
GOESY experiment, and there are some examples for
related pentadienyl24 and oxopentadienyl17 iridium spe-
cies. Differentiation of the syn and anti isomers was not
possible based on the absence of vicinal coupling con-
stants, but there was evidence of spatial interaction
between the H3 and Me(C5) and H1-syn with Me(C6)
for 7.
(25) Krivykh, V. V.; Gusev, O. V.; Petrovskii, P. V.; Rybinskaya, M.
I. J . Organomet. Chem. 1989, 366, 129, and references therein.
(24) Bleeke J . R.; Donaldson, A. J . Organometallics 1986, 5, 2401.

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4701
F igu r e 4. Structure of [Cp*Rh{η5-CH2C(Me)CHC(Me)O}]-
[BF4] (6).
F igu r e 3. Structure of [Cp*RhCl{η3-CH2C(Me)CHC-
(Me)O}] (10).
but the result depends on the THF/acetone ratio used.
This is due to the presence of a lithium complex in THF,
which may react with the acetone required for the
synthesis of 4-BF 4. The best synthetic procedure for
getting compound 6 is from 10 and AgBF4 (Scheme 2).
The molecular structure of 6 is described in the struc-
tural studies section (vide infra) (Figure 4).
the isomer with the allylic (C2) carbon pointing away
from the Cp* ligand.
Contrastingly, attempts to prepare the rhodium com-
pound [Cp*Rh(η5-CH2C(Me)CHC(Me)O)][PF6] in a man-
ner similar to that used for 1 were unsuccessful, giving
only the solvolysis product [(Cp*Rh)2(µ2-OPF2O)3][PF6]
(5) previously reported by Maitlis et al.4 However,
compound [Cp*Rh(η5-CH2C(Me)CHC(Me)O)][BF4] (6)
can be synthesized in moderate yield (41%), removing
1H and 13C NMR data of compound 1 in CDCl3 can
be compared to those reported by Maitlis in (CD3)2CO.2
For comparison, the 13C NMR data for both com-
pounds 1 and 6 were obtained in CDCl3, and one
interesting feature is the extreme high frequency of the
rhodium-bound CO carbon atom. In the 13C{1H} NMR
spectrum of 6 the signals for carbons C1 (δ ) 72.3), C2
(δ ) 121.5), and C3 (δ ) 85.2) are doublets with J )
9.1, 5.9, and 4.1 Hz, respectively. The coupling indicates
that C1, C2, and C3 are coordinated to the rhodium
atom, while C4 from the group CO showed a singlet at
δ ) 171.4. For compound 1 the carbon C4 resonates
quite differently (δ ) 158.7). This indicates that the
rhodium derivative experiences a strong inductive effect,
and C4 is distinctly the most positively charged carbon.
This fact could point to a contribution from a resonance
hybrid I in which there is an η3-allylic bond, as well as
the donation of the electron pair from the oxygen in 6,
while the resonance hybrid II is proposed for 1 (Scheme
4).
-
the chloride ion from compound 10 with AgBF4. If PF6
is used, a mixture of 6 and 5 is obtained in a ratio of
7.5:1. Separation of this mixture was not possible.
Treatment of compound [Cp*Rh(Me2CO)3][BF4]2 (4)3
with mesityl oxide afforded a yellow-orange solid of the
well-known [Cp*2Rh][BF4]30 in 50.3% yield. Finally,
trying to avoid the presence of acetone and PF6- ligands
with the Cp*Rh fragment, [Cp*Rh(MeCN)3][BF4]2 was
prepared as starting material, but the MeCN ligands
are not labile enough, and there was no displacement
of MeCN by mesityl oxide. In the case of [Cp*Rh(Me2-
CO)3][OTf]2 (4-OTf), the reaction mixture gave evidence
of isomerization of the mesityl oxide to the correspond-
ing 4-methylbut-4-en-2-one after 4 h at 50 °C, but this
isomerization did not progress any further, even within
2 days at the same temperature. After treatment with
1 equiv of mesityl oxide, most of the recovered product
was starting material.
Sch em e 4
An attempt to prepare compound 6 from 4-BF 4 and
lithium oxopentadienide afforded indeed, compound 6,
(26) Barabotti, P.; Diversi, P.; Ingrosso, G.; Lucherini, A.; Nuti, F.
J . Chem. Soc., Dalton Trans. 1984, 2517.
(27) Gill, D. S.; Maitlis, P. M. J . Organomet. Chem. 1975, 87, 359.
(28) Moseley, K.; Kang, J . W.; Maitlis, P. M. J . Chem. Soc. (A) 1970,
2875.
(29) (a) Lee H. B.; Maitlis, P. M. J . Chem. Soc., Chem. Commun.
1974, 601. (b) Lee H. B.; Maitlis, P. M. J . Chem. Soc., Dalton Trans.
1975, 2316.
(30) (a) Gusev, O. V.; Morozova, L. N.; Peganova, T. A.; Petrovskii,
P. V.; Ustynyuk; N. A.; Maitlis P. M. J . Organomet. Chem. 1994, 742,
359. (b) Buchholz, D.; Zsolnai, L.; Huttner, G.; Astruc, D. J . Organomet.
Chem. 2000, 593, 494.
However, on the basis of the X-ray diffraction studies
of both compounds (Figures 4 and 1, vide infra), there
is a similar interaction of the oxodienyl ligand for 6 and

4702 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Sch em e 5
1. In contrast, unexpectedly short C4-O interatomic
distances in the X-ray crystal structures of ruthenium
oxodienyl complexes have been found, for which con-
sistent high-frequency-shifted C4 chemical shifts has
been detected.31
B. Rea ction s w ith P h osp h in e Liga n d s. Ir id iu m
Com p lexes. The addition of phosphines, PR3 (R ) Ph,
Me or PR3 ) PHPh2), in acetone to compound 1 led to
the formation of compounds 11-16 as described in
Scheme 5.
our hands, the purification of this mixture was not
achieved. The 1H and 13C NMR data of iridium com-
plexes 11, 12, and 14-16 are summarized in Tables 1
and 2.
Rh od iu m Com p lexes. The addition of phosphines
PR3 (R ) Me, Ph) in methylene chloride to compound 6
led to the formation in good yield of [Cp*Rh(η3-CH2C-
(Me)CHC(Me)O)(PMe3)][BF4] (18) (83%), and in moder-
ate yield [Cp*Rh(η3-CH2C(Me)CHC(Me)O)(PPh3)][BF4]
(20) (54%) as described in Scheme 6. If the reaction
mixture, with PPh3, is evaporated to dryness after 1 h
at room temperature, the 31P NMR spectrum gives
evidence of compound 19, which is totally transformed
into compound 20, after 2 h in methylene chloride.
Compounds 18, 20, and [Cp*Rh(η3-CH2C(Me)CHC-
(Me)O)(PHPh2)][OTf] (21) can also be obtained in 19,
17, and 12% yield, respectively, by adding the corre-
sponding phosphine PR3 (R ) Me, Ph or R3 ) HPh2) in
acetone to compound 10, followed by the addition of
AgOTf. A significant improvement in yield is obtained
when the AgOTf is added to 10 first, followed by the
addition of PHPh2, affording 21 in ∼45% yield. The
former synthetic procedure using compound 10, gave 18,
[Cp*Rh(η3-CH2C(Me)CHC(Me)O)(PPh3)][OTf] (20), and
21, along with the corresponding subproducts Cp*RhCl-
(PMe3)2+ 32 and an unknown compound with a Cp* and
The complexes are air-stable in the solid state but
oxidize in solution after some time. The reactions
generally proceed at low temperature (-100 °C) and are
completed on slow warming to room temperature and
then stirring for 2 h at the same temperature. Com-
pounds [Cp*Ir(η3-CH2C(Me)CHC(Me)O)(PMe3)][PF6] (12)
and [Cp*Ir(η3-CH2C(Me)CHC(Me)O)(PHPh2)][PF6] (14)
were isolated after reducing the volume of acetone and
adding diethyl ether. They precipitated as pale yellow
solids in 95 and 77% yield, respectively. In the case of
PMe3 if the reaction mixture is immediately evaporated
to dryness, after the mixture has attained room tem-
perature the reaction showed by 31P NMR in a CDCl3
solution clear evidence for the presence of isomer [Cp*Ir-
(1,5-η-CH2C(Me)CHC(Me)O)(PMe3)][PF6] (11) as the
major compound at δ 31P ) - 44.1, along with the
corresponding signal of 12 at δ ) -36.4. After 4 h
compound 11 is a minor compound, and after 24 h 11
has been totally consumed with exclusive formation of
compound 12. Compound 11 has been characterized
only by the NMR data, while compound 13 was not even
detected. According to the 1H and 13C NMR spectra,
compounds 11 and 12 and 14 have the oxodienyl ligand
bonded to the iridium atom in a 1,5-η and η3 fashion,
respectively. Compound 14 adopts an anti conformation,
contrasting with the corresponding exo-syn ruthenium
species [Cp*Ru(η5-CH2C(Me)CHC(Me)O)(PHPh2)],1 whose
formation was carried out under cyclohexane refluxing
conditions. According to the chemical shifts, compound
12 appears to be the exo-syn isomer. This fact could be
explained by the higher reactivity of the basic PMe3
ligand. The reaction of compound 1 with PPh3 parallels
that of PMe3 and PHPh2, but this bulky PPh3 ligand
preferentially stabilizes the compound [Cp*Ir(1,5-η-
CH2C(Me)CHC(Me)O)(PPh3)][PF6] (15) (83% yield). Af-
ter heating 72 h at 40 °C, 15 in CDCl3 showed evidence
of formation of the exo-syn [Cp*Ir(η3-CH2C(Me)CHC-
(Me)O)(PPh3)][PF6] (16), which was detected by 1H NMR
spectroscopy. However, the reaction is not selective, and
there are other products along with compound 16. In
PPh3 ligand, tentatively assigned as Cp*RhCl(OTf)-
+ 34
(PPh3)33 and Cp*RhCl(PHPh2)2
.
The corresponding
ratios are 1:2.7, 4.5:1, and 1:1.1, respectively. However,
if compound 21 is prepared by first adding AgOTf to
10, followed by diphenylphosphine, a 10:1 ratio was
observed. In any case, there was no evidence of nucleo-
philic addition on the oxodienyl fragment.
1
The H and 13C NMR data for complexes 18-21 are
summarized in Tables 1 and 2.
1H NMR data demonstrate the exclusive formation
of the exo-syn derivatives 18, 20, and 21, as was also
observed for compounds 10 and 23.
Complex 18 was isolated as an air-stable yellow solid,
which after recrystallization from methylene chloride/
diethyl ether afforded single crystals, and the exo-syn
orientation of the η3-oxodienyl was confirmed by X-ray
crystallography (Figure 5, vide infra).
(32) Experimental: 1H (CDCl3) δ ) 1.81, t, 3.3 Hz; 1.65, dd, 5.7, 4.2
Hz; 31P δ ) 4.18, d, 132.6 Hz. Reported: [1H (CD3NO2): δ ) 1.80, t,
3.2 Hz, Cp*, 1.70, dd, 0.7, 11 Hz; 31P δ ) 0.8, d, 132.5 Hz]. Klingert,
B.; Werner, H. Chem. Ber. 1983, 116, 1450.
(33) CpRhCl(OTf)PPh3: 1H (CDCl3) δ ) 1.43, d, 3.5 Hz, 7.3-7.7, m.
31P δ ) 32.35, d, 143.5 Hz. 19F δ ) -78.68.
(34) Experimental: 1H (CDCl3) δ ) 1.45, t, 3.7 Hz, 6.37, d, 412 Hz,
7.3-7.8, m. 31P δ ) 13.43, d, 127.5 Hz. Reported: [1H (CDCl3) δ )
1.45, t, 3.8 Hz, 6.38, d, 411.1 Hz. 31P δ ) 13.3, d, 129.9 Hz). Esteban,
M.; Pequerul, A.; Carmona, D.; Lahoz, F. J .; Marin, A.; Oro, L. A. J .
Organomet. Chem. 1991, 402, 421.
(31) Paz-Sandoval, M. A.; J ua´rez-Saavedra, P.; Cervantes Vasquez,
M. Unpublished results.

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4703
Sch em e 6
can be present as a mixture, depending on the reaction
conditions.1
Allylic chemical shifts for compounds such as [Cp*M-
(η3-allyl)(L)]+ [M ) Rh, Ir, L ) PPh3;26,35 M ) Rh, L )
PPh3, P(OMe)3, MeCN, NH2Et;36 M ) Rh, L ) PPh3,
MeCN and M ) Rh, L ) PMe337] do not compared well
to the corresponding 14, 20, or 21.
C. Reaction with Aceton itr ile an d Water Ligan ds.
The addition at room temperature of acetonitrile to
compound 1 led to the formation of exo-anti [Cp*Ir(η3-
CH2C(Me)CHC(Me)O)(NCMe)][PF6] (22) as described in
1
Scheme 7. Through H NMR studies of pure compound
22 in CDCl3 the facile dissociation of MeCN became
evident after some minutes, along with the consequent
formation of compound 1.
The exo-anti isomer 22 structure (Figure 6) has
unequivocally been established by an X-ray diffraction
study, which will be discussed later. The analogous
rhodium compound [Cp*Rh(η3-CH2C(Me)CHC(Me)O)-
(NCMe)][BF4] (23) was also obtained in 55% yield as
the exo-syn isomer, resulting from the addition at room
temperature of acetonitrile to compound 6 (Scheme 7).
There is also dissociation of MeCN from 23, after 2 days
in methylene chloride solution. The higher stability of
the rhodium-acetonitrile bond shows that rhodium is
a hard atom compared to the soft iridium atom in
compound 22. The higher stability of the MeCN-Rh
bond is in agreement with the low reactivity observed
for [Cp*Rh(MeCN)3][BF4]2 as described above.
F igu r e 5. Structure of [Cp*Rh(PMe3){η3-CH2C(Me)CHC-
(Me)O}][BF4] (18).
Contrasting with the dominant exo-syn geometry of
the rhodium-phosphine complexes, as is the case for 21,
the corresponding iridium complex 14 exhibits prefer-
entially in solution an exo-anti (U-shaped) conformation
(Scheme 5), without evidence, at room temperature, of
the syn (W-shaped) isomer. However, slow conversion
1
from the exo-anti to exo-syn isomer was observed by H
It is interesting to compare the isomerization of 14
in CDCl3 (vide supra) and 22 in CD3CN. 14 is totally
transformed from the exo-anti to the exo-syn complex
(Table 1), while 22 under similar conditions afforded,
after 20, 46, and 88 h, an exo-anti:exo-syn ratio of 1:3.8;
1:4, and 1:4 (Table 1). The last results suggest an exo-
NMR spectroscopy, after heating the deuterated chlo-
roform solution of 14 at 50 °C. The ratio of exo-anti to
exo-syn isomers after 20, 46, and 88 h was 1:1.1, 1.0:
4.5, and 0:1, respectively.
The addition reactions of 1 and 6 (Schemes 5 and 6)
generally proceed much faster than those observed for
the corresponding neutral complex Cp*Ru(2,4-dimethyl-
η5-oxopentadienyl).1 The selectivity of rhodium and
iridium compounds is evident, and it is interesting to
contrast, as far as their conformations are concerned,
the strongly preferred exo-syn conformation for rhodium
complexes, and the exo-anti for some iridium complexes
(vide infra), while for ruthenium analogues both isomers
(35) Bertani, R.; Diversi, P.; Ingrosso, G.; Lucherini, A.; Marchetti,
F.; Adovasio, V.; Nardelli, M.; Pucci, S. J . Chem. Soc., Dalton Trans.
1988, 2983.Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1986,
108, 7346.
(36) Rigby, W.; Lee, H.-B.; Bailey, P. M.; McCleverty, J . A.; Maitlis,
P. M. J . Chem. Soc., Dalton Trans. 1979, 387.
(37) Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1986, 108,
7346.

4704 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Sch em e 7
F igu r e 7. Structure of [Cp*Rh(H2O){η3-CH2C(Me)CHC-
(Me)O}][BF4] (24).
F igu r e 6. Structure of [Cp*Ir(NCMe){η3-CH2C(Me)CHC-
(Me)O}][PF6] (22).
Attempts to synthesize 24 from 6 and CDCl3/H2O did
not give spectroscopic evidence of reaction, even after
20 days at room temperature. 6 and D2O affords
deuterated 24.
anti, exo-syn equilibrium, favored by the presence of
acetonitrile in compound 22.
The orientation of the allylic moiety with respect to
the other ligands has been studied for different allylic
derivatives, such as [Cp′M(η3-allyl)(CO)]+ [M ) Rh, Ir;
Cp′ ) Cp,38 Cp*]39 and [Cp*Ir(η3-allyl)(η2-CH2CH2)]+.40
A detailed study on the stereochemistry of metal-allyl
cationic complexes25 and theoretical studies of the
interconversion between endo and exo η3-allyl for [CpIr-
(η3-allyl)PH3]+ 41 has also been reported.
When recrystallization of complex 6 was carried out
in CH2Cl2/Et2O, red crystals of the η3-oxodienyl complex
[Cp*Rh(η3-CH2C(Me)CHC(Me)O)(H2O)][BF4] (24) were
obtained, according to an X-ray diffraction study. Traces
of water may have come from the diethyl ether or from
methylene chloride, producing serendipitously the new
complex 24 (Figure 7).
D. Attem p ted Oxid a tive Ad d ition Rea ction s. Few
examples exist of organometallic compounds of late
transition metals in high oxidation states. Comparison
with high-valent complexes of early transition metals
suggests that such compounds, especially those of
groups 8, 9, and 10, might be expected to possess unique
properties and reactivities. Recently, we studied η5-
oxopentadienyl ruthenium complexes that were found
to undergo oxidative addition of SnCl4, I2, and O2,
yielding Cp*Ru(IV)(η3-oxopentadienyl)(X1)(X2) derivatives
readily.1 Maitlis and co-workers demonstrated the ac-
cessibility of pentamethylcyclopentadienyl-substituted
organoiridium(V)42 and organorhodium(V)43 complexes.
44
Other examples reported in the literature are Cp*IrH4
and Cp*Ir(η2-2,5-Me2-thiophene)(H)2.45 As part of con-
tinuing studies of the synthesis and reactivity of oxo-
dienyl iridium and rhodium complexes, we decided to
The cationic structure in the solid state and in
solution afforded evidence of an exo-syn isomer. 1H
NMR data of the crystals afforded the spectrum of
compound 6 along with a broad signal at 3.05 ppm.
(42) Isobe, K,; Bailey, P. M.; Maitlis, P. M. J . Chem. Soc., Chem.
Commun. 1981, 808. (b) Fernandez, M. J .; Maitlis, P. M. Organome-
tallics 1983, 2, 164. (c) Isobe, K.; Andrews, D. G.; Mann, B. E.; Maitlis,
P. M. J . Chem. Soc., Chem. Commun. 1981, 809.
(43) Fernandez, M. J .; Maitlis, P. M. J . Chem. Soc., Chem. Commun.
1982, 310.
(44) Gilbert, T. M.; Bergman, R. G. Organometallics 1983, 2, 1458.
(45) Chen, J .; Daniels, L. M.; Angelici, R. J . Polyhedron 1990, 9,
1883.
(38) Krivykh, V. V.; Gusev, O. V.; Rybinskaya, M. I. J . Organomet.
Chem. 1989, 362, 351.
(39) Buchmann, B.; Piantini, U.; von Philipsborn, W.; Salzer, A.
Helv. Chim. Acta 1987, 70, 1487.
(40) (a) Wakefield, J . B.; Stryker, J . M. J . Am. Chem. Soc. 1991,
113, 7057. (b) Wakefield, J . B.; Stryker, J . M. Organometallics 1990,
9, 2428.
(41) Webster, C. E.; Hall, M. B. Organometallics 2001, 20, 5606.

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4705
Ta ble 3. Cr ysta l Da ta for Ir id iu m Com p ou n d s 1, 9, 22, a n d 25
1
9
22
25
C
16H24OPF6Ir
C22H35Ag2F4IrO5P2
925.38
P212121
9.92200(10)
14.2738(2)
20.6115(4)
90
C
20H30ON2PF6Ir
C20H30PF6I3Ir2
1180.51
P21/m
9.944(2)
12.134(2)
11.663(2)
90.0
95.43(3)
90.0
1400.9(4)
2
mol wt
cryst syst
a (Å)
569.52
651.63
P21/c
P21/n
7.9485(3)
16.5894(7)
14.8760(7)
90
14.5537(10)
9.3674(10)
18.6867(10)
90.0
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
101.9300(10)
90
1919.19(14)
4
90
90
103.392(10)
90.0
2478.3(3)
4
2919.10(8)
4
Z
cryst size (mm)
0.25 × 0.17 × 0.08
0.15 × 0.15 × 0.3
0.6 × 0.6 × 0.6
0.51 × 0.45 × 0.32
D
calc (g cm-3
)
1.971
2.106
1.746
2.799
limit 2θ (deg)
6.84-54.88
-10 e h e 10
0 e k e 21
0 e l e 19
4316
3.48-58.18
-8 e h e 13
-18 e k e 18
-25 e l e 25
16 896
4.90-60.66
-20 e h e 18
0 e k e 12
0 e l e 25
6464
5.66-49.92
-11 e he 11
0 e k e 14
0 e l e 13
5229
ranges h, k, l
total no. data
total no. unique data
total no. obsd data, F > 4σ(F)
final R1
4316
5699
5195
6284
3988
2391
2253
0.0422
0.0996
212
0.0288
0.0556
0.0849
final wR2
0.0697
0.1250
0.2302
no. variables
364
198
135
GOF
1.041
1.151
1.188
1.072
Analogous treatment of 6 with an acetone solution of
iodine afforded [(Cp*Rh)2(µ2-I)3][BF4] (26). Similar chlo-
ride- and hydroxide-bridged complexes are known, e.g.,
[(Cp*M)2(µ2-X)3]+ [M ) Rh, X ) Cl,46 OH;46,47 M ) Ir, X
) OH47].
E. Str u ctu r a l Stu d ies. Crystal data for iridium
compounds 1, 9, 22, and 25 and rhodium compounds 6,
10, 18, and 24 are provided in Tables 3 and 6, respec-
tively. The structures 1 and 6 are presented in Figures
1 and 4. These are generally similar to those of related
species.1 Some relevant data are provided in Tables 4
and 7.
The solid state structures of the η3-oxodienyl deriva-
tives 10, 18, 22, and 24 are presented in Figures 3, 5,
6, and 7, respectively, while various bonding para-
meters for iridium or rhodium compounds are contained
in Tables 4 and 7, respectively.
The solid state structure of the oxairidabenzene com-
pound 9 is presented in Figure 2, and bonding param-
eters are given in Table 5.
The crystalline structure of the complex [(Cp*Ir)2(µ2-
I)3][PF6] (25) is presented in Figure 8, and selected
bonding parameters are given in Table 8.
The bonding of the oxodienyl ligands in 1 and 6
appears similar, while the respective values for Cn-Cn+1
(n ) 1-3) and M-C(1-4) are comparatively longer,
because of weak π-back-bonding, than those for ruthen-
ium analogous species,1 while M-O bonds are quite
similar (∼2.163 Å). The corresponding atom distances
for 1 and 6 (Tables 4 and 7) reflect a significant charge
effect of the cationic iridium and rhodium complexes,
as the values for the ligand atoms (C1-C4) are length-
ened, while the bonds to O1 do not experience significant
lengthening. The O1-C4 distance in 6 is slightly shorter
[1.293(9) Å] than in 1 [1.312(10) Å] and the analogous
neutral Cp*Ru(2,4-dimethyl-η5-oxopentadienyl) [1.348(11)
Å].1
F igu r e 8. Structure of [(Cp*Ir)2(µ-I)3][PF6] (25).
explore the possibility of forming species in higher
oxidation states. However, all attempted reactions of
compounds 1 and 6 with SnCl4 and I2 afforded Cp*Ir-
(III) and Cp*Rh(III) species, losing in all cases the
oxodienyl ligand. This behavior contrasts with the
chemistry observed for the isoelectronic Cp*Ru(IV)
complexes.1
Treatment of 1 with an acetone solution of iodine or
1 M solution of SnCl4 in heptane at -110 and -78 °C
gives orange solids in 71 and 79% yield of [(Cp*Ir)2(µ2-
I)3][PF6] (25) (Figure 8) and the well-known dimer
1
[(Cp*IrCl)(µ2-Cl)]2, respectively. H NMR experiments
In general the structural parameters for the species
10, 18, and 24 correspond fairly closely to each other
and also to the neutral compound Cp*Ru[η3-CH2C(Me)-
CHC(Me)O](PPh3),1 despite the fact that the last one is
in Me2CO-d6 of both reactions show in the case of I2 that
in the initial reaction there is only evidence for the
formation of 25, while in the case of SnCl4 there is
evidence of an intermediate, which was not isolated and
which may correspond to an η3-oxodienyl species, but
is consumed later, giving only mesityl oxide and the
dimer [(Cp*IrCl)(µ2-Cl)]2.
(46) Kang, J . W.; Maitlis, P. M. J . Organomet. Chem. 1971, 30, 123.
(47) Nutton, A.; Bailey, P. M.; Maitlis, P. M. J . Chem. Soc., Dalton
1981, 1997.

4706 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles (d eg) for Com p ou n d s 1 a n d 22
1
22
1
22
Bond Distances
C11-C12
C14-C15
C11-C15
C15-C16
C11-C17
C12-C18
C13-C19
C14-C20
Ir-O1
Ir-C1
2.175(8)
2.204(7)
2.222(7)
2.245(8)
2.173(3)
2.171(3)
2.192(3)
2.206(3)
2.194(3)
1.412(11)
1.434(11)
1.443(11)
1.484(11)
1.509(12)
1.4227(11)
1.512(2)
2.212(9)
2.182(9)
2.183(9)
1.4227(19)
1.4228(19)
1.4227(19)
1.512(2)
1.512(2)
1.512(2)
1.512(2)
1.512(2)
2.159(6)
1.312(10)
1.498(10)
1.529(9)
1.510(8)
1.476(11)
1.540(8)
1.459(10)
C11-C16
1.481(18)
1.425(17)
1.411(16)
1.503(17)
1.460(17)
1.494(16)
1.498(18)
1.119(12)
2.045(7)
1.222(12)
1.491(12)
1.556(13)
1.570(10)
1.492(12)
1.431(13)
1.513(12)
Ir-C2
Ir-C3
Ir-C4
C12-C13
C12-C17
C13-C14
C13-C18
C14-C19
C7-N1
Ir-C11
Ir-C12
Ir-C13
Ir-C14
Ir-C15
C1-C2
C2-C3
C3-C4
C4-C5
C2-C6
C-C(Cp*)
C-Me(Cp*)
2.224(10)
2.180(10)
2.193(9)
2.183(9)
2.182(10)
1.439(14)
1.445(14)
1.478(14)
1.485(17)
1.521(14)
1.416(16)
1.497(17)
Ir-N1
O1-C4
F1-P1
F1-P2
F2-P2
F3-P2
F4-P2
F5-P2
F6-P2
F2-P1
F3-P1
F4-P1
F5-P1
F6-P1
Bond Angles
C4-C3-Ir
C1-C2-Ir
C3-C2-Ir
C6-C2-Ir
C5-C4-Ir
C1-C2-C3
C1-C2-C6
C2-C3-C4
C3-C2-C6
C3-C4-C5
O1-C4-C3
O1-C4-C5
O1-C4-Ir
121.7(8)
120.3(7)
124.6(7)
117.3(7)
120.6(7)
118.6(7)
120.8(8)
69.1(4)
118.3(9)
120.5(10)
125.2(9)
120.9(10)
116.9(10)
123.2(10)
119.9(11)
72.0(4)
70.1(4)
71.8(4)
123.3(6)
131.0(6)
111.8(6)
72.1(5)
70.7(5)
122.3(7)
96.5(4)
176.8(11)
104.3(3)
84.6(4)
N1-Ir-C14
N1-C7-C8
N1-Ir-C2
N1-Ir-C1
Ta ble 5. Bon d Len gth s (Å) a n d An gles (d eg) for
Com p ou n d 9
C1-C2 [1.439(14) Å] and Ir-C1 [2.212(9) Å] distances
for 22, which are longer than those of the corresponding
exo-syn [Cp*Ru(η3-oxodienyl)(PPh3)] [1.407(5), 2.189(3)
Å] and rhodium complex 24 [1.400(6), 2.164(4) Å]. The
η3-oxodienyl ligand for the rhodium and iridium com-
pounds coordinates preferentially through carbon atoms
rather than through an oxoallyl, as observed for the soft
Ru(II) analogue derivatives.1 The average CdO distance
is 1.221 Å. Typical bond distances for Ir-NCMe (2.045
Å) were observed for compound 22 and [Ir2(COD)2-
(NCMe)(Tcbiim)] (Tcbiim ) 4,4′,5,5′-tetracyano-2,2′-
biimidazole) [2.044(12) Å]48 and Rh-O (2.187(3) Å) for
24, similar to that found for [Cp*Rh(Me2CO)2(OH)]+ 31
(2.180(4) Å) and shorter and longer than those for
[Cp*Rh(H2O)3]2+ [2.213(8), 2.131(8), and 2.137(8) Å].49
The substituents L ) Cl, PMe3, and H2O for 10, 18, and
24 are opposite the carbonyl group, while for L ) MeCN
in 22 it is on the same side of the CdO group. This
arrangement is in accord with the exo-syn and exo-anti
conformations of the oxodienyl ligands in each case.
The solid state study of compound 9 shows disorder
in one of the tert-butyl groups with an occupancy of 50:
50. The structure confirms the metallabenzene structure
with an Ir(III) center. This inorganic polymer is bridging
the Ir and C1 through the dimer [Ag(O2PF2)]2. The
structure has two planar rings, the Cp* and the iri-
daoxabenzene, which are perpendicular (93.7°) to each
other. In the six-membered ring, the interior angle at
Ir is 88.15(13)°, and that at O is 131.9(2)°; the interior
angles at the four carbons range from 122.8(3)° to
125.2(4)°. The six-membered ring is nearly planar, with
no atom deviating by more than 0.079 Å from the best
mean plane. Bond distances also suggest that the ring
can be represented as an aromatic system. The bond
length of Ir-C1 (2.000(4) Å) is similar to those for
iridabenzenes [2.024(8) and 1.985(8) Å]50 and shorter
Bond Lengths
Ir-O1
1.998(3)
2.000(4)
2.142(6)
2.150(7)
2.228(9)
1.534(4)
1.530(4)
1.528(4)
1.517(5)
1.417(5)
1.412(5)
1.389(5)
1.535(5)
1.553(5)
1.309(5)
1.518(8)
1.373(8)
Ir1-Ag1
Ir1-Ag2
Ir1-C11
Ir1-C14
Ag1-O2
Ag2-O4
Ag1-O5A
Ag1-C1
Ag2-C1
P1-O2
2.7670(7)
2.7708(7)
2.146(4)
2.297(6)
2.278(6)
2.379(7)
2.116(7)
2.455(9)
2.296(9)
1.469(6)
1.418(8)
1.372(7)
1.487(8)
1.533(6)
1.512(11)
1.452(10)
1.581(11)
Ir-C1
Ir-C12
Ir-C13
Ir-C15
P1-F1
P1-F2
P2-F3
P2-F4
C1-C2
C2-C3
C3-C4
C4-C5
C2-C6
O1-C4
C11-C16
C13-C14
P1-O3
P2-O4
P2-O5
C5-C25
C6-C23
C12-C13
C12-C17
Bond Angles
O1-Ir-C1
88.15(3)
132.1(3)
168.18(15)
103.2(2)
162.5(3)
123.3(3)
103.67(16)
39.6(3)
136.4(4)
153.2(3)
63.7(2)
76.0(2)
80.0(2)
O1-Ir-Ag2
C1-Ir-Ag2
C11-Ir-Ag2
C1-Ag1-Ir
O1-Ir-Ag2
C12-Ir-Ag2
C15-Ir-Ag2
O1-C4-C3
C1-C2-C3
C3-C4-C5
C1-C2-C6
O4-Ag2-Ir
O3-P1-F1
F2-P1-F1
O4-P2-F4
F4-P2-F3
O2-Ag1-Ir
84.64(19)
54.7(3)
O1-Ir-C12
O1-Ir-C11
O1-Ir-C13
C1-Ir-C13
C1-Ir-C12
C1-Ir-C11
C12-Ir-C13
O1-Ir-C15
C1-Ir-C14
C12-Ir-C15
Ir-C1-Ag1
Ir-C1-Ag2
C2-C1-Ir
101.8(5)
44.53(10)
84.64(19)
142.16(18)
83.8(2)
123.3(4)
123.1(3)
122.8(3)
119.5(3)
101.19(17)
101.5(5)
98.9(3)
127.5(3)
89.8(6)
94.9(6)
C2-C1-Ag1
C2-C1-Ag2
Ag1-Ir-Ag2
106.6(5)
98.0(3)
146.43(16)
113.056(13)
a Ru(II) species, while others are Rh(III). Each complex
contains an η3-oxodienyl ligand as an exo-syn isomer,
contrasting with the crystalline structure of the cationic
Ir(III) complex 22, which contains an η3-oxodienyl ligand
in an exo-anti conformation. The bonding parameters
within the oxodienyl ligands are quite similar indepen-
dently of their conformations, except for the terminal
(48) Rasmussen, P. G.; Bailey, O. H.; Bayon, J . C. Inorg. Chem. 1984,
23, 338.
(49) Eisen, M. S.; Haskel, A.; Chen, H.; Olmstead, M. M.; Smith, D.
P.; Maestre, M. F.; Fish, R. H. Organometallics 1995, 14, 2806.

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4707
Ta ble 6. Cr ysta l Da ta for Rh od iu m Com p ou n d s 6, 10, 18, a n d 24
6
10
18
24
C
16H24BF4ORh
C16H24OClRh
370.71
C19H33OPBF4Rh
498.14
C16H26O2BF4Rh
440.09
mol wt
cryst syst
a (Å)
422.07
P22121
P21/n
P1h
P21/c
7.3972(3)
14.5614(6)
16.4645(7)
90
7.260(5)
27.038(5)
9.010(5)
90
113.498(5)
90
9.1825(2)
10.4846(2)
12.3365(3)
97.9940(10)
97.4550(10)
98.5480(10)
1149.29(4)
2
10.8608(4)
12.3331(4)
14.5758(5)
90
107.076(2)
90
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
90
90
1773.45(13)
4
1622.0(15)
4
1866.32(11)
4
Z
cryst size (mm)
0.1 × 0.08 × 0.03
0.45 × 0.39 × 0.25
0.5 × 0.2 × 0.05
0.1 × 0.05 × 0.1
D
calc (g cm-3
)
1.581
1.518
1.439
1.566
limit 2θ (deg)
7.40-59.94
-9 e h e 9
-18 e k e 16
-21 e l e 21
12 580
5.78-53.86
0 e h e 9
0 e k e 34
-11 e l e 10
4041
4.78-54.94
-11 e h e 11
-13 e k e 11
-15 e l e 16
8889
6.02-55.00
-14 e h e 14
-15 e k e 16
-18 e l e 18
23 814
ranges h, k, l
total no. data
total no. unique data
total no. obsd data, F > 4σ(F)
final R1
4031
3945
5231
4258
3096
2189
4822
2887
0.0573
0.0631
0.0395
0.0432
final wR2
0.1275
0.1691
0.1072
0.0839
no. variables
178
172
271
248
GOF
1.040
1.429
1.146
1.038
Ta ble 7. Selected Bon d Len gth s (Å) a n d An gles (d eg) for Com p ou n d s 6, 10, 18, a n d 24
6
10
18
24
Bond Lengths
Rh-O1
Rh-C1
Rh-C2
Rh-C3
Rh-C4
Rh-C10
Rh-C11
Rh-C12
Rh-C13
Rh-C14
O1-C4
C1-C2
C2-C3
C3-C4
C4-C5
C2-C6
C-C(Cp*)
C-Me(Cp*)
B1-F4
2.162(5)
2.188(8)
2.221(7)
2.194(7)
2.244(8)
2.172(3)
2.154(3)
2.152(3)
2.168(3)
2.180(3)
1.293(9)
1.391(14)
1.431(14)
1.438(12)
1.486(12)
1.488(12)
1.4216(17)
1.5112(18)
1.305a(14)
1.369(17)
Rh-Cl
2.422(3)
Rh-P2
2.3352(7)
2.190(3)
2.160(3)
2.206(3)
Rh-O2
2.187(3)
2.164(4)
2.186(5)
2.197(5)
2.189(12)
2.173(12)
2.193(11)
2.242(12)
2.185(11)
2.210(12)
2.161(12)
2.208(12)
1.221(17)
1.394(17)
1.435(16)
1.469(18)
1.51(2)
2.201(3)
2.220(3)
2.242(3)
2.258(3)
2.228(3)
1.222(5)
1.401(5)
1.423(5)
1.484(5)
1.498(6)
1.515(5)
1.4324(4)
1.4968(4)
1.288(9)
1.296(6)
1.358(6)
2.217(4)
2.191(4)
2.171(4)
2.155(4)
2.151(4)
1.222(5)
1.400(6)
1.423(6)
1.462(6)
1.496(7)
1.507(7)
1.4242(6)
1.5032(6)
1.368(6)
1.351(6)
1.361(6)
1.509(16)
1.421(15)
1.504(15)
B1-F2
B1-F3
Bond Angles
C1-C2-C3
C3-C2-C6
C2-C3-C4
C1-C2-C6
C1-C2-Rh
C3-C2-Rh
C4-C3-Rh
C6-C2-Rh
C2-C3-Rh
O1-C4-C3
O1-C4-C5
C2-Rh-C3
C1-Rh-C3
120.5(7)
117.4(11)
125.1(8)
121.0(11)
70.3(5)
115.0(11)
124.9(11)
125.6(12)
120.1(11)
72.0(7)
116.5(3)
124.5(3)
125.4(3)
119.0(3)
72.35(18)
72.71(17)
116.0(2)
123.7(2)
69.26(17)
123.8(3)
119.7(4)
38.03(14)
66.22(14)
88.13(9)
107.29(9)
115.3(4)
124.1(4)
127.3(4)
120.4(5)
70.4(3)
70.1(4)
73.0(4)
71.6(6)
71.5(3)
114.9(9)
122.9(10)
70.1(7)
125.7(14)
121.2(15)
38.4(4)
66.0(5)
85.2(4)
104.8(4)
118.4(3)
123.8(4)
70.6(3)
123.9(4)
119.6(4)
37.88(17)
66.27(18)
82.48(18)
101.04(17)
122.9(5)
72.1(5)
119.3(7)
121.5(8)
37.8(4)
68.0(4)
C1-Rh-Cl
C2-Rh-Cl
C1-Rh-P2
C2-Rh-P2
C1-Rh-O2
C2-Rh-O2
a
F1-B1.
than iridacyclohexadienes [2.161(11), 2.127(8), and
2.143(7) Å].51 Considering the planar, delocalized bond-
ing indicated by the X-ray results and the aromatic
characteristics of the NMR spectrum, complex 9 is
reasonably described as a metallaheterobenzene deriva-
tive, best described as an “iridaoxabenzene”, analogous
to the “iridathiabenzene” described by Angelici.20 Bond
distances between Ag1 and Ag2 with C1 are 2.455(9)
and 2.296(9) Å, respectively. These values are an
indication of the π nature of the silver-carbon bond, as
has been previously observed in other silver com-
pounds.52 To our knowledge, the only reported type of
similar ring is the iridapyrylium complex [{IrCHC(Me)-
CHC(Me)O}(PEt3)3]+,19 but the crystal structure has not

4708 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
Ta ble 8. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 25
points were determined using a Mel-Temp apparatus and are
not corrected.
Syn th esis of [Cp *Ir (η5-CH2C(Me)CHC(Me)O)][P F 6] (1).
To an acetone solution (10 mL) containing 200 mg of [Cp*IrCl2]2
(0.25 mmol) at room temperature was added AgPF6 (253 mg,
1.0 mmol) previously weighed in a drybox and dissolved in
acetone (3 mL). The solution was stirred for 15 min under
nitrogen atmosphere, and AgCl was then filtered. The addition
resulted in a change in color from orange to yellow. To the
filtered yellow solution, mesityl oxide (70 µL, 0.6 mmol) was
added. The solution was then warmed to 50 °C and stirred for
30 min. Afterward, the yellow solution was allowed to cool to
room temperature, the solvent was reduced, and diethyl ether
was added, precipitating compound 1 as a yellow powder,
which can be crystallized in chloroform/diethyl ether. 1 was
obtained in 68% yield (192 mg, 0.337 mmol) and decomposes
at ∼174 °C, without melting. X-ray quality crystals were
obtained by diffusion crystallization with nitromethane/diethyl
ether. Spectroscopic and physical properties have been previ-
ously reported.2
Bond Lengths
Ir1-C1
Ir1-C2
Ir1-C3
Ir1-I1
Ir1-I2
P1-F1
P1-F2
P1-F3
P1-F4
Ir2-I1
Ir2-I2
2.122(18)
2.185(19)
2.15(3)
2.7264(19)
2.7257(13)
1.58(2)
1.550(16)
1.571(19)
1.586(17)
2.7288(17)
2.7273(13)
Ir2-C1A
Ir2-C2A
Ir2-C3A
C1-C2
C2-C3
C3-C4
C1-C6
C2-C5
C3-C4
2.145(16)
2.160(16)
2.14(2)
1.40(3)
1.47(2)
1.44(4)
1.52(3)
1.48(3)
1.44(4)
Bond Angles
C1A-Ir1-C1
C1-Ir1-C3
C1-Ir1-C2A
C3-Ir1-C2
C2A-Ir2-I1
38.4(12)
65.5(8)
64.2(8)
39.6(6)
131.5(5)
C1-Ir1-I1
C1-Ir1-I2
Ir1-I1-Ir2
Ir1-I2-Ir2
I2-Ir2-I1
100.5(5)
120.2(6)
81.05(5)
81.09(4)
82.87(4)
been published. The difluorophosphate rhodium struc-
ture of [Rh2(Cp)2(µ-CO)(µ-dppm)(µ-AgOPF2O)] has been
published.53
The single-crystal X-ray structure determination of
[(Cp*Ir)2(µ2-I)3][PF6] (25) shows bond lengths and angles
similar to those previously reported for [(Cp*Ir)2I6]54 and
[(Cp*Ir)2I4].55 Each iridium atom has a distorted octa-
hedral coordination with a Cp* occupying three coordi-
nation sites and three iodine atoms surrounding the
cationic Ir(III).
Attem p ted Syn th esis of Com p ou n d 6. Syn th esis of
[(Cp *Rh )2(µ2-OP F 2O)3][P F 6] (5). To an acetone solution (10
mL) containing 100 mg of [Cp*RhCl2]2 (0.162 mmol) at room
temperature was added AgPF6 (163 mg, 0.648 mmol) previ-
ously weighed in a drybox and dissolved in acetone (3 mL).
The solution was stirred for 15 min under nitrogen atmo-
sphere, and AgCl was then filtered. The addition resulted in
a change in color from brick-red to yellow. To the filtered
yellow solution was added mesityl oxide (44 µL, 0.38 mmol).
The solution was then warmed to 50 °C and stirred for 40 min.
Afterward, the yellow solution was allowed to cool to room
temperature, the solvent was reduced, and diethyl ether was
added, precipitating compound 5 as an orange-yellow powder
in 92% yield (138 mg, 0.149 mmol). Mp: 219-221 °C. Spec-
troscopic and crystallographic data and physical properties
have been previously reported.2,4
Syn th esis of [Cp *Rh (η5-CH2C(Me)CHC(Me)O)][X] [X )
P F 6, BF 4] (6). To a CH2Cl2 solution (5 mL) containing 150
mg of compound 10 (0.40 mmol) at room temperature was
added AgPF6 (102 mg, 0.40 mmol) in 2 mL of CH2Cl2. The
addition resulted in a change in color from dark brown to
yellow and then red-brown. The amber suspension was stirred
at room temperature for 30 min and was then filtered. After
reducing the volume of the volatiles, diethyl ether (20 mL) was
added and the yellow-greenish solid that precipitated was
purified by fast chromatography through Celatom FW-50 (2
cm × 10 cm), eluting with CH2Cl2. Attempts to purify with
CH2Cl2/diethyl ether (0.5/20 mL) afforded compound 6-P F 6
mixed with 5 as a bright yellow powder (88 mg) in a ratio of
7.5:1, respectively. The synthesis of 6-BF 4 was carried out
similarly as described for 6-P F 6, using AgBF4 (80 mg, 0.40
mmol), and 69 mg (0.163 mmol, 40.8%) was isolated. Mp: 137-
139 °C. Anal. Calcd for C16H24BF4ORh: C, 45.53; H, 5.73.
Found: C, 45.83, H, 5.98. MS: 335(100) [M - BF4+], 237(10).
Syn th esis of Cp *Ir Cl[η3-CH2C(Me)CHC(Me)O] (7). Un-
der a nitrogen atmosphere, a n-BuLi (0.32 mL, 1.6 M, 0.5
mmol) solution was added to a cold (-78 °C) THF solution (1.0
mL) of diisopropylamine (70 µL, 0.5 mmol). The solution was
stirred with slow warming to room temperature. After 15 min
the solution was cooled to -78 °C, and mesityl oxide (57 µL,
0.5 mmol) was added dropwise. The solution was then warmed
to room temperature and stirred for 1 h, after which a light
yellow solution was observed. The resulting (oxopentadienyl)-
lithium salt was slowly added dropwise to a cold (-110 °C)
solution of [Cp*IrCl2]2 (200 mg, 0.25 mmol) in 4.0 mL of THF.
After the solution was warmed to room temperature and
stirred for 2 h, the volatiles were removed under vacuum.
Compound 7 was then extracted from the remaining residue
with diethyl ether, and the resulting solution was concentrated
and then chromatographed on a neutral Al2O3 (1.0 × 15 cm)
column with diethyl ether as the eluant. A yellow band was
Exp er im en ta l Section
Gen er a l P r oced u r es. Standard inert-atmosphere tech-
niques were used for all syntheses and sample manipulations.
The solvents were dried by standard methods (hexane and
pentane with CaH2, diethyl ether and THF with Na/benzophen-
one, CH2Cl2, CHCl3, and CH3NO2 with CaCl2, acetone with
K2CO3, benzene and toluene with Na, CH3CN with P2O5) and
distilled under nitrogen prior to use. Compounds [Cp*MCl2]2
[M ) Rh, Ir]3b and 2,2,5,6,6-pentamethyl-4-hepten-3-ona,56
were prepared according to literature procedures. All other
chemicals were used as purchased from Sigma-Aldrich, Strem
Chemicals, Merck, J . T. Baker, Isotec, and Cambridge Isotopes.
Elemental analyses were performed by Robertson Microlit
Laboratories, Inc., Madison, NJ , and Desert Analytics, Tucson,
AZ. Solution IR spectra were recorded on a Perkin-Elmer
6FPC-FT spectrophotometer using KBr or a CHCl3 solution
1
in NaCl plates. H, 13C, and 31P NMR spectra were recorded
on J EOL GSX-270, J EOL Eclipse+400 MHz, or Bruker 300
MHz spectrometers in deoxygenated, deuterated solvents.
NMR chemical shifts are reported relative to TMS and 31P
NMR chemical shifts relative to 85% H3PO4. Mass spectra were
obtained at Washington University, St. Louis, MO. Melting
(50) Bleeke, J . R. Acc. Chem. Res. 1991, 24, 271.
(51) Bleeke J . R.; Boorsma, D.; Chiang, M. Y.; Clayton, T. W., J r.;
Haile, T.; Beatty, A. M.; Xie, Y.-F. Organometallics 1991, 10, 2391.
(52) (a) Ning, G. L.; Wu, L. P.; Sugimoto, K.; Munakata, M.; Kuroda-
Sowa, T.; Maekawa, M. J . Chem. Soc., Dalton Trans. 1999, 2529. (b)
Munakata, M.; Wu, L. P.; Kuroda-Sowa, T.; Maekawa, M.; Suenaga,
Y.; Ning, G. L.; Kojima, T. J . Am. Chem. Soc. 1998, 120, 8610. (c)
Munakata, M.; Wu, L. P.; Sugimoto, K.; Kuroda-Sowa, T.; Maekawa,
M.; Suenaga, Y.; Maeno, N.; Fujita, M. Inorg. Chem. 1999, 38, 5674.
(d) J anssen, M. D.; Ko¨hler, K.; Herres, M.; Dedieu, A.; Smeets, W. J .
J .; Spek, A. L.; Grove, D. M.; Lang, H.; Van Koten, G. J . Am. Chem.
Soc. 1996, 118, 4817.
(53) Bruno, G.; Schiavo S. L.; Piraino P.; Faraone, F. Organometal-
lics 1985, 4, 1098.
(54) Millan, A.; Bailey, P. M.; Maitlis, P. M. J . Chem. Soc., Dalton
Trans. 1982, 73, and references therein.
(55) Churchill, M. R.; J ulis, S. A. Inorg. Chem. 1979, 18, 1215.
(56) Ernst, R. D.; Freeman, J . W.; Swepston, P. N.; Wilson, D. R. J .
Organomet. Chem. 1991, 402, 17.

Half-Open Rhodocenium and Iridocenium
Organometallics, Vol. 21, No. 22, 2002 4709
eluted. The solvent was removed in vacuo, and the crude
product was crystallized from diethyl ether/pentane at -20
°C to give 47 mg (0.1 mmol, 20%) of 7 as yellow crystals. Mp:
156-160 °C. Anal. Calcd for C16H24ClOIr: C, 41.77; H, 5.25.
Found: C, 42.03, H, 5.36. MS: 425(100) [M - Cl+], 363(16).
IR (CHCl3, cm-1): 1658 (CdO).
from amber to light yellow and then bright yellow. The solution
was allowed to warm slowly to room temperature and was
stirred for 1.5 h and then filtered. After removal of the
volatiles, the oily residue was dissolved in a minimum amount
of acetone, and diethyl ether was added, giving a pale yellow
precipitate in 77% yield (102 mg, 0.135 mmol). Mp: 118-120
°C. Anal. Calcd for C28H35F6IrOP2: C, 44.50; H, 4.66. Found:
C, 44.29, H, 4.40. MS: 611(100) [M - PF6+], 513(63), 425(35).
IR (CHCl3, cm-1): 1666 (CdO).
Syn th esis of [Cp *Ir (1,5-η-CH2C(Me)CHC(Me)O)P P h 3]-
[P F 6] (15). To an acetone solution (10 mL) containing 100 mg
of compound 1 (0.175 mmol) at -78 °C was added PPh3 (50.0
mg, 0.19 mmol) in acetone (2 mL). The addition resulted in a
change in color from amber to orange-yellow. The solution was
allowed to warm slowly to room temperature and was stirred
for 2 h and then filtered. After removal of the volatiles, the
oily residue was washed with pentane (2 × 20 mL). The yellow
solid was dissolved in a minimum amount of acetone, and
diethyl ether was added, affording a yellow precipitate in 83%
yield (122 mg, 0.146 mmol). Mp: 163-165 °C. Anal. Calcd for
Syn th esis of [(Cp *Ir )2(µ2-OP F 2O)3][P F 6] (8) a n d Cp *
Ir Ag2(µ2-OP F 2O)2[η1:1-CHC(CMe3)CHC(CMe3)O] (9). To an
acetone solution (10 mL) containing 200 mg of [Cp*IrCl2]2 (0.25
mmol) at room temperature was added AgPF6 (253 mg, 1.0
mmol) previously weighed in a drybox. The addition resulted
in a change in color from orange to yellow. The solution was
stirred for 15 min under nitrogen atmosphere, and AgCl was
then filtered. To the yellow filtrate was added dropwise
2,2,5,6,6-pentamethyl-4-hepten-3-one (0.12 mL, 0.6 mmol). The
solution was then warmed to 50 °C and stirred for 15 min.
Afterward, the amber solution was allowed to cool to room
temperature, the solvent was reduced, and diethyl ether was
added, precipitating compound 8 as a pale yellow powder in
66% yield (168 mg, 0.165 mmol). Mp: 173-175 °C, decomp.
Anal. Calcd for C20H30F12O6P4Ir2: C, 21.78; H, 2.74. Found:
C, 22.64, H, 2.88. MS: 957(65) [M - PF6+], 751(100), 701(60),
687(35), 671(30), 664(22).
C
34H39F6IrOP2: C, 49.09; H, 4.72. Found: C, 49.16, H, 4.62.
MS: 687(42) [M - PF6+], 589(52), 425(73). IR (CHCl3, cm-1):
1620 (CdO).
The remaining orange solution after a couple of hours at
room temperature afforded compound 9 as dark red crystals
in 65% yield (134 mg, 0.164 mmol). Mp: 167-171 °C. Crystals
suitable for X-ray analysis were obtained directly at room
temperature. Anal. Calcd for C22H35Ag2F4IrO5P2: C, 28.55; H,
3.81. Found: C, 27.98, H, 3.70. MS: 929 [M]+ (2.5), 835 (5),
615 (35), 505 (10), 1124 (100). HRMS: 929.2936. IR (KBr, cm
-1): 1530 (CdO), 1316 (PdO); 837 (P-F).
Syn th esis of [Cp *Rh (η3-CH2C(Me)CHC(Me)O)P Me3][X]
(X ) BF 4, OTf) (18). To a CH2Cl2 solution (10 mL) containing
100 mg of compound 6-BF 4 (0.237 mmol) at -110 °C was added
PMe3 (27 µL, 0.26 mmol). The addition resulted in a change
in color from orange to yellow and then amber. The solution
was allowed to warm slowly to room temperature and was
stirred for 2 h and then filtered. After removal of the volatiles,
the oily residue was washed with pentane (3 × 10 mL) and
diethyl ether (2 × 10 mL). The orange-yellow solid was
dissolved in a minimum amount of CH2Cl2 and purified by
chromatography on a Celatom FW-50 column (1 × 10 cm)
using methylene chloride as eluent. Evaporation of the solvent
under vacuum afforded a yellow compound 18-BF 4 in 83%
yield (101 mg, 0.197 mmol). Mp: 124-127 °C, decomp. Anal.
Calcd for C19H33OPBF4Rh: C, 45.81; H, 6.67. Found: C, 45.92,
H, 6.57. MS: 411(100) [M - BF4+]. IR (CHCl3, cm-1): 1670
(CdO).
Compound 18-OTf was obtained from an acetone solution
(10 mL) containing 100 mg of compound 10 (0.269 mmol) at
-110 °C. PMe3 (31 µL, 0.295 mmol) was added, the reaction
mixture was allowed to warm slowly to room temperature, and
AgOTf (69 mg, 0.269 mmol) was added previously dissolved
in acetone (2 mL), stirred for 2 h, and then filtered. After
removal of the volatiles, the oily residue was recrystallized
from chloroform/diethyl ether, affording an orange-yellow solid
(29 mg) as a mixture of 18 and [Cp*RhCl(PMe3)2]+ 32 in a ratio
of 1:2.7, respectively.
Syn th esis of [Cp *Rh (η3-CH2C(Me)CHC(Me)O)P P h 3][X]
[X ) BF 4, OTf] (20). To a CH2Cl2 solution (10 mL) containing
100 mg of compound 6-BF 4 (0.237 mmol) at -110 °C was added
PPh3 (62 mg, 0.237 mmol), dissolved in CH2Cl2 (2 mL). The
addition resulted in a change in color from orange to red and
then yellow. The solution was allowed to warm slowly to room
temperature and was stirred for 3 h and then filtered. After
removal of the volatiles, the oily residue was washed with
pentane (3 × 10 mL) and dissolved in a minimum amount of
methylene chloride, and addition of diethyl ether afforded a
yellow compound 20-BF 4 in 53.6% yield (87 mg, 0.127 mmol).
Mp: 119-121 °C. MS: 597(100) [M - BF4+], 695(10), 433(5).
IR (CHCl3, cm-1): 1670 (CdO).
Compound 20-OTf was obtained from an acetone solution
(10 mL) containing 100 mg of compound 10 (0.269 mmol) at
-110 °C. PPh3 (71 mg, 0.269 mmol) in acetone (2 mL) was
added. The reaction mixture was allowed to warm slowly to
room temperature, and AgOTf (69 mg, 0.269 mmol) was added
previously dissolved in acetone (2 mL). The amber solution
was stirred for 2 h and then filtered. After removal of the
volatiles, the oily residue was washed with pentane (3 × 10
Syn th esis of Cp *Rh Cl[η3-CH2C(Me)CHC(Me)O] (10).
Under a nitrogen atmosphere, a n-BuLi (1.0 mL, 1.6 M, 1.62
mmol) solution was added to a cold (-78 °C) THF solution (2.0
mL) of diisopropylamine (0.25 mL, 1.62 mmol). The solution
was stirred with slow warming to room temperature. After 15
min the solution was cooled to -78 °C and mesityl oxide (0.18
mL, 1.62 mmol) was added dropwise. The solution was then
warmed to room temperature and stirred for 1 h, after which
a light yellow solution was observed. The resulting (oxopen-
tadienyl)lithium salt was slowly added dropwise to a cold
(-110 °C) solution of [Cp*RhCl2]2 (500 mg, 0.81 mmol) in 5.0
mL of THF. After the solution was warmed to room temper-
ature and stirred for 2 h, the volatiles were removed under
vacuum. Compound 10 was then extracted from the remaining
residue with diethyl ether, and the resulting brick-red solution
was concentrated and then chromatographed on neutral Al2O3
(1.0 × 20 cm) column with diethyl ether as the eluant. A brick-
red band was collected. The solvent was removed in vacuo,
and the crude product was crystallized from diethyl ether/
pentane at -10° to give 449 mg (1.21 mmol, 74.8%) of 10 as
brick-red crystals that decompose at 105 °C. Anal. Calcd for
C
16H24ClORh: C, 51.84; H, 6.52. Found: C, 52.46, H, 6.53.
MS: 370(13) [M+], 335(100) [M - Cl+], 273(84), 237(46). IR
(CHCl3, cm-1): 1654 (CdO).
Syn th esis of [Cp*Ir (η3-CH2C(Me)CHC(Me)O)P Me3][P F6]
(12). To an acetone solution (10 mL) containing 100 mg of
compound 1 (0.175 mmol) at -110 °C was added PMe3 (20 µL,
0.19 mmol). The addition resulted in a change in color from
amber to light yellow and then amber. The reaction mixture
was allowed to warm slowly to room temperature and was
stirred for 2 h and then filtered. After removal of the volatiles,
the oily residue was dissolved in a minimum amount of
acetone, and diethyl ether was added, giving a pale yellow
precipitate in 95% yield (108 mg, 0.167 mmol). Mp: 202-205
°C. IR (CHCl3, cm-1): 1674 (CdO). LR/ESI: 501 (100) [M -
PF ] +, 446 (10), 425 (5), 278 (5).
6
Syn th esis of [Cp *Ir (η3-CH2C(Me)CHC(Me)O)P HP h 2]-
[P F 6] (14). To an acetone solution (10 mL) containing 100 mg
of compound 1 (0.175 mmol) at -110 °C was added PHPh2
(32 µL, 0.18 mmol). The addition resulted in a change in color

4710 Organometallics, Vol. 21, No. 22, 2002
Rangel Salas et al.
mL) and recrystallized from chloroform/diethyl ether, affording
a yellow solid (34 mg) as a mixture of compound 20 and
Cp*RhCl(OTf)(PPh3)33 in a 4.5:1 ratio, respectively.
into a saturated nitromethane solution. Anal. Calcd for
C20H30F6I3Ir2P: C, 20.34; H, 2.56. Found: C, 20.47; H, 2.43.
MS: 1035(100) [M - PF6+], 954(10), 908(28).
Syn th esis of [Cp *Rh (η3-CH2C(Me)CHC(Me)O)P HP h 2]-
[OTf] (21). The synthesis was carried out similarly as
described for 18-OTf (vide supra), using PHPh2 (51 µL, 0.295
mmol). After removal of the volatiles, the orange-yellow oily
solid was dissolved in a minimum amount of acetone, and
diethyl ether was added, precipitating a yellow solid that is a
mixture (21.6 mg) of compound 21 and [Cp*RhCl(PHPh2)2]+
(ratio 1:1.1, respectively). Also compound 21-OTf was obtained
from an acetone solution (10 mL) containing 100 mg of
compound 10 (0.269 mmol) at -110 °C, and AgOTf (69 mg,
0.269 mmol) was added previously dissolved in acetone (2 mL).
The reaction mixture was allowed to warm slowly to room
temperature and then stirred for 30 min. The yellow solution
was cooled again to -110 °C, and 31 µL (0.295 mmol) of PHPh2
was added. The reaction mixture was allowed to warm slowly
to room temperature and then stirred for 2 h and filtered. After
removal of the volatiles, the oily residue was recrystallized
from acetone/diethyl ether, affording an orange-yellow solid
that is a mixture of 21 and [Cp*RhCl(PHPh2)2]+ 34 (82 mg) in
a ratio of 10:1.
Syn th esis of [(Cp *Rh )2(µ2-I)3][BF 4] (26). The synthesis
was carried out similarly as described for 25 (vide supra), using
6-BF 4 (25 mg, 0.06 mmol) and 11.5 mg (0.05 mmol) of I2 in
acetone (2 mL). A red-brown precipitate in 78% yield (22 mg,
0.023 mmol) was isolated. It does not melt until 230 °C. MS:
856.9 [M - BF4+].
Syn th esis of [Cp *Ir Cl(µ2-Cl)]2. To an acetone solution (10
mL) containing 100 mg of compound 1 (0.175 mmol) at -78
°C was added a heptane solution of SnCl4 (1 M, 0.35 mL, 0.35
mmol). The addition resulted in a change in color from amber
to light yellow and then yellow-brown. The yellow-brown
solution was allowed to warm slowly to room temperature and
was stirred for 1 h and then filtered. After removal of the
volatiles, the oily residue was washed with pentane (3 × 10
mL) and diethyl ether (1 × 10 mL). The light yellow solid was
dissolved in a minimum amount of nitromethane, and diethyl
ether was added, affording an orange precipitate in 79% yield
(55 mg, 0.069 mmol), which did not melt below 230 °C.
Spectroscopic data and physical properties have been previ-
ously reported.3b
Syn th esis of [Cp *Ir (η3-CH2C(Me)CHC(Me)O)MeCN]-
[P F 6] (22). A MeCN solution (10 mL) containing 100 mg of
compound 1 (0.175 mmol) was stirred for 1 h at room
temperature. The volume of the yellow solution was reduced
to ∼0.5 mL, and diethyl ether was added (20 mL), giving a
pale yellow precipitate of 22 in 66% yield (70 mg, 0.12 mmol).
Mp: 97-99 °C. Crystals suitable for X-ray analysis were
deposited at -10 °C from acetonitrile solutions. Anal. Calcd
for C18H27F6IrNOP‚MeCN: C, 36.86; H, 4.64. Found: C, 36.47;
H, 4.68. MS: 467(4) [M - PF6+], 425(42), 313 (40). IR (CHCl3,
cm-1): 1677 (CdO).
Syn th esis of [Cp *2Rh ][BF 4]. To an acetone solution (10
mL) containing 200 mg of [Cp*RhCl2]2 (0.32 mmol) at room
temperature was added AgBF4 (252 mg, 1.3 mmol) in acetone
(3 mL). The solution was stirred for 15 min under nitrogen
atmosphere and AgCl was then filtered. To the yellow filtrate
was added dropwise mesityl oxide (90 µL, 0.78 mmol). The
solution was then warmed to 50 °C and stirred for 105 min.
Afterward, the yellow solution was allowed to cool to room
temperature, the solvent was reduced, and diethyl ether was
added, precipitating [Cp*2Rh][BF4] as an yellow-orange powder
in 53% yield (153 mg, 0.34 mmol), which did not melt below
230 °C. Spectroscopic and crystallographic data and physical
properties have been previously reported.19
X-r a y Str u ctu r e Deter m in a tion for 1, 6, 9, 10, 18, 22,
24, a n d 25. Crystal data and experimental details are given
in Tables 3 and 6. X-ray data were collected on Enraf-Nonius
four-circle or Siemens diffractometers using graphite-mono-
chromated Mo KR (λ ) 0.7107 Å) radiation. Final positional
parameters are available as Supporting Information.
Syn th esis of [Cp *Rh (η3-CH2C(Me)CHC(Me)O)MeCN]-
[BF 4] (23). The synthesis was carried out similarly as de-
scribed for 22 (vide supra), using compound 6 (50 mg, 0.12
mmol). A yellow precipitate in 55% yield (30.5 mg, 0.065 mmol)
was isolated. Mp: 109-111 °C. Anal. Calcd for C18H27BF4-
NORh: C, 46.68; H, 5.87. Found: C, 46.61; H, 5.63. MS: 376
(<1) [M - BF4+], 355(100). IR (CHCl3, cm-1): 1665 (CdO).
Syn th esis of [Cp*Rh (η3-CH2C(Me)CHC(Me)O)H2O][BF4]
(24). Compound 24 was obtained from a CH2Cl2 solution (0.5
mL) containing 53 mg of compound 6 (0.13 mmol). Diethyl
ether (20 mL) was added separately for a crystallization under
slow diffusion of the ether on the CH2Cl2 solution. Recrystal-
lization at -10 °C during 2 days yielded a few red crystals,
without a melting point.
Ack n ow led gm en t. M.A.P.S. would like to thank
Conacyt for financial support through the project 26352-
E, as well as for the X-ray diffractometer (No. F0084),
and Washington University Mass Spectrometry Re-
search Resource (NIH, No. P41RR0954) for recording
some of the mass spectra. I.I.R.S. thanks also Conacyt
for a scholarship. Thanks to Marco Antonio Leyva and
Ma. Esther Sa´nchez Castro for helping us with some
X-ray diffraction studies. We would like to thank Prof.
Peter M. Maitlis for crystallographic data of compound
[Cp*Rh]2(µ2-OPO2F2) and interesting comments.
Syn th esis of [(Cp *Ir )2(µ2-I)3][P F 6] (25). To an acetone
solution (10 mL) containing 100 mg of compound 1 (0.175
mmol) at -110 °C was added I2 (44 mg, 0.175 mmol) in acetone
(2 mL). The addition resulted in a change in color from amber
to brown and then orange. The orange solution was allowed
to warm slowly to room temperature and was stirred for 1 h
and then filtered. After removal of the volatiles, the oily
residue was washed with pentane (2 × 20 mL) and diethyl
ether (1 × 10 mL). The red solid was dissolved in the minimum
amount of nitromethane, and diethyl ether was added, afford-
ing an orange precipitate in 71% yield (74 mg, 0.062 mmol),
which decomposed at 155 °C. Red crystals suitable for X-ray
analysis were deposited after slow diffusion of diethyl ether
Su p p or tin g In for m a tion Ava ila ble: X-ray complemen-
tary data. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM020400Q