Reactions of bis[dichloro(pentamethylcyclopentadienyl)rhodium(III) and -iridium(III)] with aromatic phosphine bearing a methoxy group at an ortho-position: Double insertion of 1-alkynes into a Rh-O bond

Article abstract of DOI:10.1016/S0020-1693(02)01021-6

Reactions of [Cp*MCl₂]₂ (1a: M = Rh, 1b: M = Ir; Cp* = C₅Me₅) with 2-methoxyphenylphosphines at room temperature gave the corresponding ¹η-P coordination complexes, [Cp*MCl₂(PPh_3-nR_n)] (2: n = 1; 4: n = 2; 6b: n = 3 for R = C₆H₄-2-MeO). Reaction of 1 with (2-methoxyphenyl)diphenylphosphine at reflux in diglyme underwent demethylation to afford Cp*MCl(MMMPP-P,O) (3) (M = Rh, Ir; MMMPP-P,O = PPh₂(C₆H₄-2-O)) with a (P,O) chelating ligand. In the reaction with bis(2-methoxyphenyl)phenylphosphine, Cp*MCl(BMMPP-P,O) (5) (M = Rh, Ir; BMMPP-P,O = PPh(C₆H₄-2-MeO)(C₆H₄-2-O)) was generated at reflux in a mixture of diglyme and MeOH. Tris(2-methoxyphenyl)phosphine reacted with 1a at reflux in MeOH to give Cp*RhCl(TMMPP-P,O) (7a) (TMMPP-P,O = P(C₆H₄-2-MeO)₂(C₆H ₄-2-O)), whereas the reaction with 1b at reflux in EtOH generated Cp*Ir(TMMPP-P,O,O′) (8b) (TMMPP-P,O,O′ = P(C₆H₄-2-MeO)(C₆H₄-2-O) ₂) with a (P,O,O′) tridentate ligand. Crystal structural analyses of 3a, 5a and 8b were carried out. Complex 3a underwent a double insertion of alkyne into a Rh-O bond on treatment with phenylacetylene or p-tolylacetylene in the presence of KPF₆, giving [Cp*Rh{PPh₂(C₆H₄-O-CR=CH-CH=CR}](PF ₆) (9a: R = p-MeC₆H₄; 9b: R = Ph) with a (P,O,C) tridentate ligand, in which X-ray crystal analysis of 9a was performed.

Full text of DOI:10.1016/S0020-1693(02)01021-6

Inorganica Chimica Acta 340 (2002) 21ꢃ28
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www.elsevier.com/locate/ica
Reactions of bis[dichloro(pentamethylcyclopentadienyl)rhodium(III)
and -iridium(III)] with aromatic phosphine bearing a methoxy group
at an ortho-position: double insertion of 1-alkynes into a Rhꢀ
/
O bond
Yasuhiro Yamamoto *, Kenichiro Sugawara, Masateru Kakeya
Department of Chemistry, Faculty of Science, Toho University, Miyama, 2-2-1, Funabashi, Chiba 274-8510 Japan
Received 10 December 2001; accepted 27 April 2002
Abstract
Reactions of [Cp*MCl2]2 (1a: Mꢀ
the corresponding 1h-P coordination complexes, [Cp*MCl2(PPh3ꢁnRn)] (2: nꢀ
Reaction of with (2-methoxyphenyl)diphenylphosphine at reflux in diglyme underwent demethylation to afford
Cp*MCl(MMMPP-P,O) (3) (MꢀRh, Ir; MMMPP-P,OꢀPPh2(C6H4-2-O)) with a (P,O) chelating ligand. In the reaction with
bis(2-methoxyphenyl)phenylphosphine, Cp*MCl(BMMPP-P,O) (5) (MꢀRh, Ir; BMMPP-P,OꢀPPh(C6H4-2-MeO)(C6H4-2-O))
was generated at reflux in a mixture of diglyme and MeOH. Tris(2-methoxyphenyl)phosphine reacted with 1a at reflux in MeOH to
give Cp*RhCl(TMMPP-P,O) (7a) (TMMPP-P,OꢀP(C6H4-2-MeO)2(C6H4-2-O)), whereas the reaction with 1b at reflux in EtOH
generated Cp*Ir(TMMPP-P,O,O?) (8b) (TMMPP-P,O,O?ꢀP(C6H4-2-MeO)(C6H4-2-O)2) with a (P,O,O?) tridentate ligand.
Crystal structural analyses of 3a, 5a and 8b were carried out. Complex 3a underwent a double insertion of alkyne into a RhꢀO bond
on treatment with phenylacetylene or p-tolylacetylene in the presence of KPF6, giving [Cp*Rh{PPh2(C6H4-O-CRꢁCHꢀCHꢁ
CR}](PF6) (9a: Rꢀp-MeC6H4; 9b: RꢀPh) with a (P,O,C) tridentate ligand, in which X-ray crystal analysis of 9a was performed.
# 2002 Elsevier Science B.V. All rights reserved.
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Rh, 1b: Mꢀ
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Ir; Cp*ꢀ
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C5Me5) with 2-methoxyphenylphosphines at room temperature gave
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1; 4: nꢀ2; 6b: nꢀ3 for RꢀC6H4-2-MeO).
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Keywords: 2-Methoxyphenylphosphines; Bis[dichloro(pentamethylcyclopentadienyl)rhodium(III) and -iridium(III)]; PꢀO chelating ligand; Double
/
insertion of alkyne
1. Introduction
P,O) and Cp*M(TDMPP-P,O,O?) (Mꢀ
Cp*ꢀ BDMPP-P,OꢀPPh{C6H3-2,6-
h5-C5Me5;
(MeO)2} (C6H3-2-O-6-MeO), TDMPP-P,O,O?ꢀ
P{C6H3-2,6-(MeO)2} (C6H3-2-O-6-MeO)2) with biden-
tate (h2-P,O) or tridentate (h3-P,O,O?) chelating phos-
phines, respectively.
Recently, we reported that these (h2-P,O) and (h3-
P,O,O?) chelating complexes of rhodium(III) and
iridium(III) reacted readily with strongly electron-defi-
cient olefin such as tetracyanoethylene and 7,7,8,8-
tetracyano-p-quinodimethane, which inserted into
/
Rh and Ir;
/
/
We have reported that one or two of the ortho-
methoxy groups in (2,6-dimethoxyphenyl)diphenylpho-
sphine, bis(2,6-dimethoxyphenyl)phenylphosphine, and
tris(2,6-dimethoxyphenyl)phosphine were demethylated
in the reactions with bis[dichloro(h6-arene)ruthenium-
(II)] [1] or bis[dichloro(h5-pentamethylcyclopentadie-
nyl)rhodium(III) or -iridium(III)] [2,3], giving (h6-arene)
RuCl(MDMPP-P,O), (h6-arene)RuCl(TDMPP-P,O)
/
(areneꢀ
and C6Me6; MDMPP-P,Oꢀ
TDMPP-P,O ꢀP {C6H3-2,6-(MeO)2}2(C6H3-2-O -6-
MeO)), Cp*MCl(MDMPP-P,O), Cp*MCl(BDMPP-
/p-cymene, 1,2,3-Me3C6H3, 1,3,5-Me3C6H3,
weakly activated Cꢀ/H bonds on the phenyl ring of the
/
PPh2(C6H3-2-O-6-MeO),
phosphine ligand [4]. In the reactions of alkynes with
(h2-P,O) chelating rhodium complexes in the presence
of KPF6, they underwent the single- or double insertion
/
of alkyne into a Rhꢀ
/
O bond to generate five-, six- and
seven-membered metallacycles, the transannular addi-
tion of alkyne between metal atom or ipso-carbon atom
of the phosphine, and the insertion of alkyne into a
* Corresponding author. Tel.: ꢂ
1855
E-mail address: yamamoto@chem.sci.toho-u.ac.jp (Y. Yamamoto).
/
81-474-72 5076; fax: ꢂ
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81-474-75
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 0 2 1 - 6

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Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ28
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metalꢀ
the metal atom and the chelating phosphine ligand [5ꢃ
7].
We were interested in chemistry of less bulky 2-
methoxyphenylphosphines in comparison with 2,6-di-
methoxyphenylphosphines. 2-Methoxyphenylpho-
sphines are known to lead to O- or C-metallation with
various metal complexes. Thus, 2-methoxyphenyl-di-t-
butylphosphine, PBu2t (C6H4OMe-2), in the reactions
with platinum(II) complexes is metallated much more
readily than PPh2(C6H4OMe-2), and PMe2(C6H4OMe-
2) could not be metallated [8,9]. These metallations are
promoted by steric effects.
We have now investigated the reactions of 2-methox-
yphenylphosphines with bis[dichloro(pentamethylcyclo-
pentadienyl)rhodium(III) or -iridium(III)], compared
with 2,6-dimethoxyphenylphosphines, and performed
the reaction of the resulting metallated complex with
alkyne.
/
P bond, depending on the nature of the alkyne,
31P{1H} NMR (CDCl3): d 0.56 (s). Anal. Calc. for
C29H32Cl2IrOP: C, 50.43; H, 4.67. Found: C, 50.06; H,
4.55%.
/
2.1.2. At reflux
A mixture of 1a (1.0 g, 1.62 mmol) and (2-methox-
yphenyl)diphenylphosphine (1.04 g, 3.56 mmol) in
diglyme (40 ml) was refluxed for 10 h. The solvent was
removed in vacuo and the residue was washed with
Et2O. The solid was recrystallized from CH2Cl2 and
Et2O to give brown crystals of [Cp* RhCl{PPh2(C6H4-
2-O)}] (3a) (1.34 g, 74.9%). UVꢃ
/
Vis (CH2Cl2): lmax 400
(sh), 334, 255 nm. H NMR (CDCl3): d 1.50 (d, JPH
3.0 Hz, Cp*, 15H), 6.9ꢃ
7.6 (m, ArH, 14H). 31P{1H}
NMR (CDCl3): d 49.3 (d, JRhP 142 Hz). Anal. Calc.
for C28H29ClOPRh: C, 61.05; H, 5.31. Found: C, 60.76;
H, 5.40%. Complex 3b (orange, 91.8%): UVꢃVis
(CH2Cl2): lmax 330 nm. H NMR (CDCl3): d 1.53 (d,
JPH 2.0 Hz, Cp*, 15H), 6.5ꢃ
8.0 (m, ArH, 14H). 31P
NMR (CDCl3): 26.7 (s). Anal. Calc. for
1
ꢀ
/
/
ꢀ
/
/
1
ꢀ
/
/
d
C28H29ClIrOP: C, 52.53; H, 4.57. Found: C, 52.23; H,
4.62%.
2. Experimental
All complexes were carried out under nitrogen atmo-
sphere. Dichloromethane was distilled over CaH2 and
Et2O was distilled over LiAlH4. 2-Methoxyphenylphos-
2.2. Reactions of 1a or 1b with bis(2-
methoxyphenyl)phenylphosphine
phines [10] and [Cp*MCl2]2 (Mꢀ
/
Rh [11], Ir [7]; Cp*ꢀ
/
2.2.1. At room temperature
C5Me5) were prepared according to the literature. The
IR and electronic absorption spectra were measured on
FT/IR-5300 and U-best 30 instruments, respectively.
NMR spectroscopy was carried out on a Bruker AC250.
The H NMR spectra were measured at 250 MHz, and
31P{1H} NMR spectra were measured at 100 MHz using
85% H3PO4 as an external reference.
A mixture of 1a (0.30 g, 0.486 mmol) and bis(2-
methoxyphenyl)phenylphosphine (0.356 mg, 1.10 mmol)
in CH2Cl2 (15 ml) was stirred for 5 h at room
temperature (r.t.) and the solvent was removed. The
residue was chromatographed on alumina (containing
10% water) using CH2Cl2 as an eluent after washing of
the residue with Et2O. The eluate was concentrated and
1
Et2O was added to form orangeꢃ
/
brown crystals of 4a
Vis (CH2Cl2):
lmax 408, 278 nm. H NMR (CDCl3): d 1.35 (d, JPH
2.5 Hz, Cp*, 15H), 3.40 (b, MeO, 6H), 6.8ꢃ8.0 (m, ArH,
13H). 31P NMR (CDCl3): d 26.0 (d, JRhP
146 Hz).
0.5CH2Cl2: C, 54.36;
2.1. Reaction of 1a with (2-
methoxyphenyl)diphenylphosphine
(0.486 g, 74.2%) contained CH2Cl2. UVꢃ
/
1
ꢀ
/
/
2.1.1. At room temperature
ꢀ
/
A mixture of 1a (0.300 g, 0.485 mmol) and (2-
methoxyphenyl)diphenylphosphine (0.350 g, 1.20
mmol) was stirred in CH2Cl2 (30 ml) for 5 h. The
solvent was removed in vacuo and the residue was
washed with Et2O. The solid was recrystallized from
CH2Cl2 and Et2O to give yellow crystals of
[Cp*RhCl2{PPh2(C6H4-2-MeO)}] (2a) (0.375 g,
Anal. Calc. for C30H34Cl2O2PRh×
/
H, 5.24. Found: C, 54.02; H, 5.30%. Complex 4b
(64.3%) was prepared according to a procedure similar
1
to 4a. UVꢃ
(CDCl3): d 1.32 (d, JPH
MeO, 6H), 6.8ꢃ
7.9 (m, ArH, 13H). 31P{1H} NMR
(CDCl3): d ꢁ1.50 (s). Anal. Calc. for C30H34Cl2IrO2P:
/Vis (CH2Cl2): lmax 322, 287 nm. H NMR
ꢀ2.0 Hz, Cp*, 15H), 3.38 (b,
/
/
/
64.3%). UVꢃ
NMR (CDCl3): d 1.32 (d, JPH
3.27 (s, MeO, 3H), 6.7ꢃ
8.2 (m, ArH, 14H). 31P{1H}
NMR (CDCl3): d 29.1 (d, JRhP 142 Hz). Anal. Calc.
/
Vis (CH2Cl2): lmax 408, 274 nm. 1H
4.0 Hz, Cp*, 15H),
C, 50.00; H, 4.76. Found: C, 50.02; H, 5.00%.
ꢀ
/
/
2.2.2. At reflux
ꢀ
/
A mixture of 1b (0.610 g, 0.766 mmol) and bis(2-
methoxyphenyl)phenylphosphine (0.538 mg, 1.699
mmol) was refluxed in diglyme (10 ml) and MeOH (30
ml) for 10 h. The solvent was removed in vacuo and the
residue was washed with Et2O. The solid was chroma-
for C29H32Cl2OPRh: C, 57.92; H, 5.36. Found: C, 58.16;
H, 5.44%.
Complex 2b (66.3%) was obtained according to a
procedure similar to 1a. UVꢃ
/
Vis (CH2Cl2): lmax 350,
289 nm. H NMR (CDCl3): d 1.32 (d, JPH 2.0 Hz,
Cp*, 15H), 3.27 (s, MeO, 3H), 6.7ꢃ8.0 (m, ArH, 14H).
1
ꢀ
/
tographed on alumina (10% water), using CH2Cl2ꢃ
/
/
MeOH (16:1) as an eluant. Yellow eluate was concen-

Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ
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28
23
trated to give yellow solid of 5b (0.683 mg, 66.5%). The
solid was recrystallized from CH2Cl2 and Et2O for
(CDCl3): d 34.5 (s). Anal. Calc. for C30H33ClIrO3P: C,
51.46; H, 4.75. Found: C, 51.47; H, 4.80%.
purification. 1H NMR (CDCl3): d 1.53 (d, JPH
ꢀ
/
2.5
7.9 (m, ArH,
The yellow solid [Cp*IrP(C6H4-2-MeO)(C6H4-2-
O)2}] (8b) (18.9%) was generated by refluxing in EtOH
for 0.5 h, followed by chromatography on alumina (10%
Hz, Cp*, 15H), 3.78 (s, MeO, 3H), 6.4ꢃ
/
13H). 31P NMR (CDCl3): d 35.0 (s). Anal. Calc. for
C29H31ClIrO2P: C, 51.97; H, 4.66. Found: C, 52.31; H,
1
water), using CH2Cl2 and C6H6 (4:1) as an eluant. H
4.59%. Reddishꢃ
/
brown complex of 5a (68.3%) were
Vis (CH2Cl2): lmax 338, 260
nm. H NMR (CDCl3): d 1.52 (d, JPH 3.0 Hz, Cp*,
15H), 3.81 (s, MeO, 1H), 6.4ꢃ
8.0 (m, ArH, 13H). 31P
NMR (CDCl3): d 48.7 (d, JRhP 141 Hz). Anal. Calc.
MNR (CDCl3): d 1.53 (d, JPH
(s, MeO, 3H), 6.4ꢃ
7.8 (m, ArH, 13H). 31P NMR
(CDCl3): d 20.8 (s). Anal. Calc. for C29H30IrO3P×
ꢀ2.0 Hz, Cp*, 15H), 3.20
/
obtained as well as 5b. UVꢃ
/
/
1
ꢀ
/
/
/
0.5CH2Cl2: C, 51.19; H, 4.51. Found: C, 51.60; H,
ꢀ
/
4.87%.
for C29H31ClO2PRh: C, 59.96; H, 5.38. Found: C, 60.02;
H, 5.31%.
2.5. Reaction of 3a with p-tolylacetylene
2.3. Reaction of 1a with tris(2-methoxyphenyl)phosphine
A mixture of 3a (0.050 mg, 0.091 mmol), tolylacety-
lene (0.10 ml, 0.91 mmol) and KPF6 (0.167 mg, 0.91
mmol) was stirred in CH2Cl2 (15 ml) and C3H6O (10 ml)
at r.t. After 48 h, the solvent was removed and the
residue was extracted with CH2Cl2 and the solution was
filtered with a glass filter. After the solvent was
removed, the residue was washed with Et2O and
A mixture of 1a (0.150 g, 0.243 mmol) and tris(2-
methoxyphenyl)phosphine (0.250 mg, 0.71 mmol) was
stirred for 4 h at reflux in MeOH (20 ml). The solvent
was removed in vacuo and the residue was washed with
Et2O. The solid was chromatographed on alumina (10%
water), using CH2Cl2 as an eluant. Brown eluate was
concentrated to give brown solid of [Cp*RhCl{P(C6H4-
recrystallized from CH2Cl2ꢃ
dishꢃbrown crystals of 9a (0.029 mg, 35.3%). FAB mass
(m/z): 747 [Mꢂ]. IR (Nujol): 1574 (Cꢁ
C), 841 (PF6)
cmꢁ1. UVꢃVis (CH2Cl2): lmax 365 nm. 1H MNR
(CDCl3): d 1.39 (d, JPH 2.5 Hz, Cp*, 15H), 2.15 (s,
p-Me, 3H), 2.44 (s, p-Me, 3H), 6.30 (d, JHH 7.5 Hz,
1H), 6.46 (d, JHH 7.5 Hz, 1H), 6.7ꢃ7.7 (m, ArH, 22H).
31P{1H} NMR (CDCl3): d 37.4 (d, JRhP
158 Hz), ꢁ
140.2 (sep, JPF 712 Hz). Anal. Calc. for
C46H45F6OP2Rh×0.5CH2Cl2: C, 59.72; H, 4.96. Found:
C, 59.25; H, 4.95%. Analogously, reddishꢃbrown com-
plex 9b was prepared by the reaction of 3a with
/
MeOHꢃ/Et2O, giving red-
/
2-MeO)2(C6H4-2-O)}] (7a) (0.683 g, 66.5%). UVꢃ
(CH2Cl2): lmax ca. 410 (sh), 366, 253 nm. 1H NMR
(CDCl3): d 1.53 (d, JPH 2.5 Hz, Cp*, 15H), 3.20 (bs,
OMe, 6H), 3.72 (bs, OMe, 3H), 6.5ꢃ8.0 (m, ArH, 14H).
31P{1H} NMR (CDCl3): d 40.9 (d, JRhP
155 Hz).
0.25CH2Cl2: C, 57.43;
/Vis
/
/
ꢀ
/
ꢀ
/
/
ꢀ
/
ꢀ
/
ꢀ
/
/
Anal. Calc. for C30H33ClO3PRh×
/
ꢀ
/
/
H, 5.37. Found: C, 57.98; H, 5.46%.
ꢀ
/
/
2.4. Reaction of 1b with tris(2-methoxyphenyl)phosphine
/
2.4.1. At room temperature
phenylacetylene. FAB mass (m/z): 719 [Mꢂꢁ
/
1]. IR
A mixture of 1b (0.230 g, 0.289 mmol) and tris(2-
methoxyphenyl)phosphine (0.250 mg, 0.710 mmol) was
stirred for 3 h at r.t. in CH2Cl2 (15 ml). The solvent was
removed in vacuo and the residue was washed with
Et2O. The residue was recrystallized from CH2Cl2 and
(Nujol): 1575 (Cꢁ
/
C), 839 (PF6) cmꢁ1
.
(CH2Cl2): lmax 257 nm. H NMR (CDCl3): d 1.39 (d,
UVꢃVis
/
1
JPH
6.44 (d, JHH
31P{1H} NMR (CDCl3): d 37.3 (d, JRhP
140.0 (sep, JPF 712 Hz). Anal. Calc. for
0.5CH2Cl2: C, 56.92; H, 4.56. Found:
ꢀ
/
2.7 Hz, Cp*, 15H), 6.31 (d, JHH
7.5 Hz, 1H), 6.8ꢃ7.7 (m, ArH, 24H).
163 Hz), ꢁ
ꢀ
/
7.5 Hz, 1H),
ꢀ
/
/
ꢀ
/
/
Et2O, giving yellow crystals of 6b (0.325 mg, 75%). UVꢃ
/
ꢀ
/
Vis (CH2Cl2): lmax ca. 360 (sh), ca. 310, 287 nm. Anal.
Calc. for C31H36Cl2IrO3P: C, 49.60; H, 4.83. Found: C,
49.62; H, 4.99%.
C44H41F6OP2Rh×
/
C, 56.94; H, 4.61%.
2.6. Data collection
2.4.2. At reflux
A mixture of 1b (0.150 g, 0.188 mmol) and tris(2-
methoxyphenyl)phosphine (0.250 mg, 0.710 mmol) was
stirred for 4 h at reflux in MeOH (20 ml). The solvent
was removed in vacuo and the residue was washed with
Et2O. The solid was chromatographed on alumina (10%
water), using CH2Cl2 as an eluant. Brown eluate was
concentrated to give brown solid of [Cp*IrCl{P(C6H4-
All complexes were recrystallized from C3H6O/Et2O
or CH2Cl2/ether. Cell constants were determined from
20 reflections on Rigaku four-circle automated diffract-
ometer AFC5S. The crystal parameters along with data
collections are summarized in Table 1S (see Section 5).
Data collection was carried out by a Rigaku AFC5S
refractometer at 27 8C. Intensities were measured by
2-MeO)2(C6H4-2-O)}] (7b) (0.149 mg, 56.6%). UVꢃ
/
Vis
(CH2Cl2): lmax 328, 289 nm. H NMR (CDCl3): d 1.55
(d, JPH 2.0 Hz, Cp*, 15H), 3.21 (s, OMe, 6H), 3.73 (s,
OMe, 3H), 6.4ꢃ
7.5 (m, ArH, 14H). 31P{1H} NMR
the 2u ꢃ
/
v scan method using Mo Ka radiation (lꢀ
/
1
˚
0.71069 A). Throughout the data collection the inten-
sities of the three standard reflections were measured
every 200 reflections as a check of the stability of the
ꢀ
/
/

24
Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ28
/
crystals and no decay was observed. Intensities were
corrected for Lp effects. The absorption correction was
made with the c scan methods. Atomic scattering
factors were taken from the usual tabulation of Cromer
and Waber [12]. Anomalous dispersion effects were
included in Fcalc [13]; the values of Df? and Dfƒ were
those of Creagh and McAuley [14]. All calculations were
performed using the TEXSAN crytallographic software
package [15].
(Table 1). The Rh(1)ꢀ
/
Cl(1), Rh(1)ꢀ
/
P(1) and Rh(1)ꢀ
/
˚
O(1) bond lengths are 2.368(7), 2.293(6) and 2.13(2) A,
respectively.
Reaction with bulky bis(2-methoxyphenyl)phenyl-
phosphine was carried out at room temperature, giving
a h1-P coordination complex, [Cp*MCl2{PPh(C6H4-2-
MeO)2}] (4a: Mꢀ
/
Rh; 4b: MꢀIr). The reaction at
/
reflux in dyglyme (10 ml) and MeOH (30 ml) generated
a (P,O)-chelating complexes [Cp*MCl{PPh(C6H4-2-
MeO)(C6H4-2-O)}] (5a: Mꢀ
1
Ir). The H
/
Rh; 5b: Mꢀ
/
2.7. Determination of the structures
NMR spectra of 4 showed two characteristic resonances
at d ca. 1.35 as a doublet and at d ca. 3.40 as a singlet,
assignable to Cp* and methoxy protons, respectively.
The 31P{1H} NMR spectra showed a doublet at d 26.0
The structures of 3a, 5a, 8b and 9a were solved by
Patterson methods (DIRDIF92 PATTY). The positions
of all non-hydrogen atoms of 8b and 9a were refined
with anisotropic thermal parameters by using full-
matrix least-square methods. Heteroatoms (four atoms)
and fifteen carbon atoms for 3a and heteroatoms (five
atoms) and sixteen carbon atoms for 5a were refined
anisotropically and other non-hydrogen atoms were
refined isotropically. All hydrogen atoms were calcu-
for 4a and a singlet at d ꢁ
shift values shifted to down-field by 52.9 ppm for 4a and
25.4 ppm for 4b from that (d ꢁ26.9) of the parent
phosphine.
/
1.50 for 4b. These chemical
/
Since the phosphine ligand of 5 is bidentate, binding
through P and s-bonded O atoms, the molecule has two
chiral centers (metal and P atoms). The detailed
structure was confirmed by X-ray analysis of 5a (Fig.
2 and Table 2). A priority order of the ligand is aromatic
lated at the ideal positions with the Cꢀ
/H distance of
˚
0.95 A. Complex 8b consists of two independent
molecules.
ringꢀ
/
Clꢀ
/
Pꢀ
/
O for a metal center and Rhꢀ
/
2-O-
C6H4ꢀ
/
2-MeOC6H4ꢀ/Ph for a P center. Fig. 2 showed
that the molecule is a RhRPR/RhSPS pair. The 1H NMR
spectrum of 5a showed the presence of only one
diastereomer. The 31P{1H} NMR spectrum also sup-
ported the presence of one diastereomer, showing a
doublet at d 48.7. These NMR spectra showed that the
structure in solution is similar to that in the solid state.
However, we cannot rule out occurrence of rapid
exchange between two diastereomers. A similar behavior
was observed for the iridium complex 5b.
When 1a was treated with much bulky tri(2-methox-
yphenyl)phosphine at reflux in MeOH, brown crystals
of [Cp*RhCl{P(C6H4-2-MeO)2(C6H4-2-O)}] (7a) were
obtained. The 1H NMR spectrum showed a doublet at d
1.52 and two singlets at d 3.20 and 3.72(b), assignable to
Cp* and methoxy protons, respectively. The inequiva-
lence for the methoxy protons is assumed to arise from
the presence of a chiral center of the P atom, however, it
cannot rule out the restricted rotation of the C6H3-2-
3. Results and discussion
3.1. Reactions of [Cp*MCl2]2 with 2-
methoxyphosphines
When 1a and 1b were treated with (2-methoxyphe-
nyl)diphenylphosphine in CH2Cl2 at room temperature,
the cleavage of bridged Cl atoms readily occurred to
give yellow complexes [Cp*MCl2{PPh2(C6H4-2-MeO)}]
(2a: Mꢀ
/
Rh; 2b: MꢀIr) in ca. 65% yield (Scheme 1).
/
1
The H NMR spectra showed two characteristic reso-
nances at approximately d 1.3 as a doublet and 3.3 as a
singlet, assignable to Cp* and methoxy protons, respec-
tively. The 31P{1H} NMR spectra showed a doublet at d
29.1 for 2a and a singlet at d 0.56 for 2b. These chemical
shift values shifted to down-field by 44.9 ppm for 2a and
16.4 ppm for 2b from that (d ꢁ15.8) of the parent
/
phosphine. Similar down-field shifts have been observed
in (2,6-dimethoxylphenyl)diphenylphosphine complexes
OMe) ring about the Pꢀ
/
C axis. Reaction with iridium
complex 1b at room temperature generated yellow
complex of [Cp*IrCl2{P(2-MeOC6H4)3}] (6b), whereas
reactions at reflux in MeOH or EtOH gave a (P,O)-
chelating complex [Cp*IrCl{P(C6H4-2-MeO)2(C6H4-2-
[1ꢃ3]. Treatment at reflux in diglyme led to demethyla-
/
tion of an ortho-methoxy group of aromatic phosphine
ligand, giving metal complexes with a (P,O)-chelating
phosphine, [Cp*MCl{PPh2(C6H4-2-O)}] (3a: Mꢀ
/
Rh;
1
Ir). The H NMR spectra showed a character-
O)}]
[Cp*Ir{P(C6H4-2-MeO)(C6H4-2-O)2}] (8b).
(7b),
and
a
(P,O,O?)-chelating
one,
The
3b: Mꢀ
/
istic signal at d ca. 1.50, assignable to Cp* protons. The
31P{1H} NMR spectra showed a doublet at d 49.3 for 3a
and a singlet at d 26.7 for 3b. The X-ray analysis of 3a
revealed that the rhodium atom is surrounded by P, Cl
and O atoms in addition to Cp* moiety (Fig. 1 and
31P{1H} NMR spectra of 7b and 8b showed singlets at
d 34.5 and 20.8, again shifting to down-field by 73.2 and
59.5 ppm from that (d ꢁ38.7) of free phosphine,
/
respectively. The structure of 8b was confirmed by X-
ray analyses (Fig. 3 and Table 3). The iridium atom is
coordinated by a tridentate (P,O,O?)-chelating ligand.
Table 1). The bite P(1)ꢀ
/
Rh(1)ꢀO(1) angle is 79.7(6)8
/

Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ
/
28
25
Scheme 1. Reactions of [Cp*MC12]2 with 2-methoxyphenylphosphines (R?ꢀC6H3-2-MeO).
/
Cl bond lengths are somewhat shorter than that
˚
A)
(2.281(3)
found
in
[Cp*Ir{P(C6H3-2,6-
(MeO)2)(C6H3-2-O-6-MeO)2}] bearing a similar struc-
ture [3].
In complexes 2ꢃ7, the chemical shift values of Cp*
/
protons and coordinated P atom in h2-complexes
appeared at lower fields than those of the corresponding
h1-P complexes, being a result of high electron-with-
drawing ability of the phenoxide-oxygen atom. The
difference of the 31P chemical shift value between
complex and free phosphine increased with the number
of 2-methoxyphenyl substituent of the phosphine for h1-
P complexes (2, 4 and 6) and (P,O)-chelating complexes
(3, 5 and 7), suggesting that the electron-donating ability
increases with the number of the methoxy group in the
phosphine. It is greater in rhodium(III) complexes than
iridium(III) ones, indicating that the rhodium atom is
greater in acceptability of electron pair than the iridium
atom.
Fig. 1. Molecular structure of 3a.
The Ir(1)ꢀ
/
P(1), Ir(1)ꢀ
/
O(1) and Ir(1)ꢀ
/O(2) bond lengths
˚
are 2.266(4), 2.10(1) and 2.09(1) A, respectively. The Irꢀ
/

26
Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ28
/
Table 1
˚
Selected bond lengths (A) and angles (8) of [Cp*RhCl{(MMMPP-P,O)] (3a)
Bond lengths
Rh(1)ꢀCl(1)
O(1)ꢀC(12)
2.368(7)
1.30(3)
Rh(1)ꢀP(1)
C(11)ꢀC(12)
2.293(6)
1.44(3)
Rh(1)ꢀO(1)
P(1)ꢀC(11)
2.13(2)
1.78(2)
Bond angles
Cl(1)ꢀRh(1)ꢀP(1)
Rh(1)ꢀO(1)ꢀC(12)
Rh(1)ꢀP(1)ꢀC(11)
89.5(2)
121.0(1)
101.0(8)
Cl(1)ꢀRh(1)ꢀO(1)
O(1)ꢀC(12)ꢀC(11)
83.3(6)
118.0(2)
P(1)ꢀRh(1)ꢀO(1)
P(1)ꢀC(11)ꢀC(12)
79.7(6)
114.0(1)
Fig. 3. Molecular structure of 8b. (Only one molecule for clarity.)
Fig. 2. Molecular structure of 5a.
MeO)}]×
/
(p-tolylCꢁ
/
CH)2×
/
PF6
(p-tolylꢀ4-MeC6H4)
/
3.2. Reaction of 3a with 1-alkyne
from elementary analysis and FAB mass spectrometry
were isolated (Scheme 2). The detailed structure was
determined by X-ray analysis (Fig. 4 and Table 4). A
rhodium atom is surrounded by a (P, O, C) tridentate
ligand resulting from a head-to-head double insertion of
Previously, we have reported that reaction of
[Cp*RhCl{PPh2(C6H3-2-O-6-MeO)}] bearing a (P,O)
chelating ligand with phenylacetylene in the presence of
KPF6 led to a head-to-head double insertion of phenyl-
1-alkyne into the Rhꢀ
/O bond (Fig. 4). Two carbon
acetylene into the Rhꢀ
complex
[Cp*Rh{PPh2(C6H3-2-(O ꢀ
CPh)ꢀ6-MeO)}](PF6) (10) bearing a (P,O,C) tridentate
/
O s-bond to generate the
atoms bearing a p-tolyl group are connected to the
rhodium and oxygen atoms. The molecule contains the
five- and six-membered rings through coordination of
/
CPhꢁCHꢀCHꢁ
/
/
/
/
ligand consisting of six- and five-membered rings
sharing the rhodium atom [5,7]. A similar reaction
with 3a bearing less bulky (P,O)-chelating ligand was
carried out. When 3a was treated with p-tolylacetylene
an ether-O atom. The Rh(1)ꢀ
/
O(1) coordination bond
˚
˚
length of 2.241(4) A is ca. 0.11 A longer than that of 3a,
as expected for ether coordination as opposed to a
phenoxide. The Rhꢀ
/
P(1) and Rhꢀ
/C(39) bond lengths
˚
are 2.301(2),and 2.104(6) A, respectively, not being
significantly different from the corresponding bond
in the presence of KPF6, reddishꢃbrown crystals 9a with
/
an empirical formula as [Cp*Rh{PPh2(C6H3-2-O-6-
Table 2
˚
Selected bond lengths (A) and angles (8) of [Cp*RhCl{(BMMPP-P,O)] (5a)
Bond lengths
Rh(1)ꢀCl(1)
O(1)ꢀC(111)
2.402(8)
1.35(3)
Rh(1)ꢀP(1)
C(11)ꢀC(16)
2.315(8)
1.47(4)
Rh(1)ꢀO(1)
P(1)ꢀC(16)
2.08(2)
1.87(3)
Bond angles
Cl(1)ꢀRh(1)ꢀP(1)
Rh(1)ꢀO(1)ꢀC(111)
Rh(1)ꢀP(1)ꢀC(16)
88.8(3)
123.0(1)
100.6(10)
Cl(1)ꢀIr(1)ꢀO(1)
O(1)ꢀC(11)ꢀC(16)
90.0(6)
118.0(2)
P(1)ꢀRh(1)ꢀO(1)
C(11)ꢀC(16)ꢀP(1)
83.2(6)
114.0(2)

Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ
/
28
27
Table 3
˚
Selected bond lengths (A) and angles (8) of [Cp*Ir(TMMPP-P,O,O?)]×2H2O 8b×2H2O
Bond lengths
Ir(1)ꢀP(1)
O(1)ꢀC(12)
O(2)ꢀC(18)
Ir(2)ꢀP(2)
O(4)ꢀC(41)
O(5)ꢀC(47)
2.266(4)
1.32(2)
1.33(2)
2.277(5)
1.30(2)
1.33(2)
Ir(1)ꢀO(1)
2.10(1)
1.44(2)
1.44(2)
2.11(1)
1.41(2)
1.38(2)
Ir(1)ꢀO(2)
P(1)ꢀC(11)
P(1)ꢀC(17)
Ir(2)ꢀO(5)
P(2)ꢀC(40)
P(2)ꢀC(46)
2.09(1)
1.80(2)
1.80(2)
2.11(1)
1.78(2)
1.82(2)
C(12)ꢀC(11)
C(18)ꢀC(17)
Ir(2)ꢀO(4)
C(40)ꢀC(41)
C(47)ꢀC(46)
Bond angles
P(1)ꢀIr(1)ꢀO(1)
Ir(1)ꢀO(1)ꢀC(12)
Ir(1)ꢀP(1)ꢀC(11)
O(2)ꢀC(18)ꢀO(17)
P(2)ꢀIr(2)ꢀO(4)
Ir(2)ꢀO(4)ꢀC(41)
Ir(2)ꢀP(2)ꢀC(40)
O(5)ꢀC(47)ꢀO(46)
81.7(3)
120.0(1)
102.3(6)
123.0(1)
80.1(3)
P(1)ꢀIr(1)ꢀO(2)
O(1)ꢀC(12)ꢀC(11)
Ir(1)ꢀP(1)ꢀC(17)
Ir(1)ꢀO(2)ꢀC(18)
P(2)ꢀIr(2)ꢀO(5)
O(4)ꢀC(41)ꢀC(40)
Ir(2)ꢀP(2)ꢀC(46)
Ir(2)ꢀO(5)ꢀC(47)
81.4(3)
121.0(1)
103.9(6)
119.0(1)
81.4(4)
O(1)ꢀIr(1)ꢀO(2)
C(12)ꢀC(11)ꢀP(1)
P(1)ꢀC(17)ꢀC(18)
C(11)ꢀP(1)ꢀC(17)
O(4)ꢀIr(2)ꢀO(5)
C(41)ꢀC(40)ꢀP(2)
P(2)ꢀC(46)ꢀC(47)
C(40)ꢀP(2)ꢀC(46)
86.1(5)
112.0(1)
110.0(1)
103.2(8)
87.6(5)
121.0(1)
101.8(7)
123.0(1)
119.0(1)
102.7(6)
119.0(1)
114.0(1)
112.0(1)
104.1(8)
than the C(37)ꢀ
/
C(38) single bond and in usual Cꢀ
/
C
double bonds.
1
The H NMR spectrum showed a doublet at d 1.39
due to Cp* protons and two singlets at d 2.16 and 2.44,
assignable to p-methyl protons. The CHꢁ
/
protons
appeared at d 6.29 and 6.46 as doublets. The 31P{1H}
NMR spectra showed a doublet at d 37.4. The PF6
anion was confirmed by 31P{1H} NMR and IR spectro-
metry.
Scheme 2. Reaction of 3a with alkyne.
Analogously, complex [Cp*Rh{PPh2(C6H3-2-(O-
CPh))}](PF6) (9b) was obtained in the
reaction of 3a with phenylacetylene.
CPhꢁ
/
CHꢀ
/
CHꢁ
/
4. Summary
2-Methoxyphenylphosphines underwent demethyla-
tion of one or two methyl groups on the phenyl rings
in the reactions with [Cp*MCl2]2. These reactions are
similar to the reactions with much more bulky 2,6-
dimethylphenylphosphines, however the reactivity of 2-
methyoxyphenyl phosphines are lower than that of 2,6-
dimethoxyphenylphosphines. Thus, demethylation is
promoted by steric effects. A double insertion of the
alkyne into a Rhꢀ
/
O bond was found to occur in spite of
Fig. 4. Molecular structure of 9a.
the presence or absence of the 6-methoxy substituent on
the phenyl rings. Reactions of small molecules for the
(P,O) chelating complexes are in progress.
length for 10. The P(1)ꢀ
five-membered ring were 79.5(1)8, and the O(1)ꢀ
C(39) bite angle of the six-membered ring are 81.4(2)8.
These angles are independent of the ring-size. The P(1)ꢀ
Rh(1)ꢀC(39) bond angle of 91.0(2)8 is wider by ca. 108
/
Rh(1)ꢀ/O(1) bite angle of the
/
Rh(1)ꢀ
/
/
/
5. Supplementary material
than those of five- and six-membered rings. Similar
trend has been noted in 10. The average length of two
A listing of atomic coordinates, thermal parameters,
bond lengths, angles and torsion angles, and Table 1S,
are available from the authors on request.
double bonds, C(29)ꢀ
/
C(37) and C(38)ꢀ
/
C(39), in the
metallacyclohexadiene rings is ca. 1.34 A, being shorter
˚

28
Y. Yamamoto et al. / Inorganica Chimica Acta 340 (2002) 21ꢃ28
/
Table 4
˚
Selected bond lengths (A) and angles (8) of [Cp*Rh{PPh2(C6H4-2-(O ꢀC(p-tolyl)ꢁCHꢀCHꢁC(p-tolyl))}](PF6) (9a)
Bond lengths
Rh(1)ꢀP(1)
O(1)ꢀC(29)
C(38)ꢀC(39)
O(1)ꢀC(24)
2.301(2)
1.452(7)
1.358(9)
1.416(7)
Rh(1)ꢀO(1)
C(29)ꢀC(37)
P(1)ꢀC(23)
2.241(4)
1.320(10)
1.819(6)
Rh(1)ꢀC(39)
C(37)ꢀC(38)
C(23)ꢀC(24)
2.104(6)
1.43(1)
1.375(8)
Bond angles
O(1)ꢀRh(1)ꢀP(1)
Rh(1)ꢀO(1)ꢀC(24)
Rh(1)ꢀP(1)ꢀC(23)
C(29)ꢀC(37)ꢀC(38)
79.5(1)
119.0(3)
102.8(2)
128.1(7)
O(1)ꢀRh(1)ꢀC(39)
O(1)ꢀC(24)ꢀC(23)
Rh(1)ꢀO(1)ꢀC(29)
C(37)ꢀC(38)ꢀC(39)
81.4(2)
116.9(5)
112.5(3)
129.5(7)
P(1)ꢀRh(1)ꢀC(39)
P(1)ꢀC(23)ꢀC(24)
O(1)ꢀC(29)ꢀC(37)
Rh(1)ꢀC(39)ꢀC(38)
91.0(2)
118.6(4)
114.5(6)
115.6(6)
[5] Y. Yamamoto, X.-H. Han, J.-F. Ma, Angew. Chem. 113 (2000)
2041; Angew. Chem., Int. Ed. Engl. 39 (2000) 1965.
[6] Y. Yamamoto, K. Sugawara, J. Chem. Soc., Dalton Trans. (2000)
2896.
Acknowledgements
The authors would like to thank Professor Sigetoshi
Takahashi and Dr. Fumie Takei of The Institute of
Scientific and Industrial Research, Osaka University for
performing the FAB mass spectroscopy measurement.
[7] Y. Yamamoto, K. Sugawara, X.-H. Han, J. Chem. Soc., Dalton
Trans. (2002) 195.
[8] C.E. Jones, B.L. Shaw, B.L. Turtle, J. Chem. Soc., Dalton Trans.
(1974) 992.
[9] H.D. Empsall, B.L. Shaw, B.L. Turtle, J. Chem. Soc., Dalton
Trans. (1976) 1500.
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