Reactions of bis[dichloro(η5-pentamethylcyclopentadienyl)iridium(III)] with bulky and highly basic aromatic phosphines containing ortho-methoxy groups

Article abstract of DOI:10.1016/S0022-328X(99)00271-5

Reaction of [Cp*IrCl₂]₂ 1 (Cp=C₅Me₅) with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) at room temperature gave a monohapto-complex [Cp*IrCl₂(MDMPP-P)] 2a, whereas the reaction with bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) led to loss of one molecule of CH₃Cl to give Cp*IrCl[P(C₆H₃-2-O-6-OMe){C₆H ₃-2,6-(MeO)₂} Ph] (=Cp*IrCl(BDMPP-κ²P,O) 3b with a chelated P,O coordination, in which the structure was confirmed by an X-ray analysis: a=15.994(3) A, b=10.471(2) A, c=17.727(3) A, β=94.12(1)°, monoclinic, P2₁/n, Z=4, R=0.032. Tris(2,6-dimethoxyphenyl)phosphine (TDMPP) reacted with 1 to afford Cp*Ir[P(C₆H₃-2-O-6-OMe)₂{C ₆H₃-2,6-(MeO)₂}] (=Cp*IrCl(TDMPP-κ³P,O,O′) 4c. It was confirmed by an X-ray analysis that the molecule has a trihapto coordination (P,O,O′) derived from demethylation of two molecules of CH₃Cl: a=17.55(1) A, b=21.22(3) A, c=15.92(2) A, orthorhombic, Pbcn, Z=8, R=0.044. Complex 1 was treated with MDMPP, BDMPP or TDMPP in acetone in the presence of a PF₆ anion to give salt-like complexes [Cp*IrCl(XDMPP-κ²P,OMe)][PF₆] 5 (X=M, B, T) with a P,O coordination. The structures of 5b and 5c·CHCl₃ were confirmed by X-ray analyses: for 5b (X=B), a=11.679(2) A, b=15.389(4) A, c=10.251(3) A, α=103.92(2)°, β=91.76(2)°, γ=105.15(2)°, triclinic, P1, Z=2, R=0.046; for 5c·CHCl₃ (X=T), a=14.730(7) A, b=18.55(2) A, c=15.753(9) A, β=91.76(2)°, γ=105.45(5)°, monoclinic, P2₁/n, Z=4, R=0.048. In complexes 5a and 5b the exchange between free and coordinated OMe groups was observed, whereas in 5c such exchange was not observed. Complex 2a readily reacted with Lewis bases (L) such as isocyanide and CO in the presence of a PF₆ anion to produce [Cp*IrCl(L)(MDMPP-P)][PF₆] 6.

Full text of DOI:10.1016/S0022-328X(99)00271-5

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 587 (1999) 49–57
Reactions of
bis[dichloro(h5-pentamethylcyclopentadienyl)iridium(III)] with
bulky and highly basic aromatic phosphines containing
ortho-methoxy groups
Yasuhiro Yamamoto *, Keisuke Kawasaki, Saho Nishimura
Department of Chemistry, Faculty of Science, Toho Uni6ersity, Funabashi, Chiba 274-8510, Japan
Received 17 April 1999; received in revised form 12 May 1999
Abstract
Reaction of [Cp*IrCl2]2 1 (Cp*=C5Me5) with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) at room temperature gave
a monohapto-complex [Cp*IrCl2(MDMPP-P)] 2a, whereas the reaction with bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP)
led to loss of one molecule of CH3Cl to give Cp*IrCl[P(C6H3-2-O-6-OMe){C6H3-2,6-(MeO)2} Ph] (=Cp*IrCl(BDMPP-k2P,O) 3b
,
,
with a chelated P,O coordination, in which the structure was confirmed by an X-ray analysis: a=15.994(3) A, b=10.471(2) A,
,
c=17.727(3) A, i=94.12(1)°, monoclinic, P21/n, Z=4, R=0.032. Tris(2,6-dimethoxyphenyl)phosphine (TDMPP) reacted with
1 to afford Cp*Ir[P(C6H3-2-O-6-OMe)2{C6H3-2,6-(MeO)2}] (=Cp*IrCl(TDMPP-k3P,O,O%) 4c. It was confirmed by an X-ray
analysis that the molecule has a trihapto coordination (P,O,O%) derived from demethylation of two molecules of CH3Cl:
,
,
,
a=17.55(1) A, b=21.22(3) A, c=15.92(2) A, orthorhombic, Pbcn, Z=8, R=0.044. Complex 1 was treated with MDMPP,
BDMPP or TDMPP in acetone in the presence of a PF6 anion to give salt-like complexes [Cp*IrCl(XDMPP-k2P,OMe)][PF6] 5
(X=M, B, T) with a P,O coordination. The structures of 5b and 5c·CHCl3 were confirmed by X-ray analyses: for 5b (X=B),
,
,
,
(
a=11.679(2) A, b=15.389(4) A, c=10.251(3) A, h=103.92(2)°, i=91.76(2)°, k=105.15(2)°, triclinic, P1, Z=2, R=0.046; for
,
,
,
5c·CHCl3 (X=T), a=14.730(7) A, b=18.55(2) A, c=15.753(9) A, i=91.76(2)°, k=105.45(5)°, monoclinic, P21/n, Z=4,
R=0.048. In complexes 5a and 5b the exchange between free and coordinated OMe groups was observed, whereas in 5c such
exchange was not observed. Complex 2a readily reacted with Lewis bases (L) such as isocyanide and CO in the presence of a PF6
anion to produce [Cp*IrCl(L)(MDMPP-P)][PF6] 6. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: (2,6-Dimethoxyphenyl)diphenylphosphine; Bis(2,6-dimethoxyphenyl)phenylphosphine; Tris(2,6-dimethoxyphenyl)phosphine; Bis-
[dichloro(pentamethylcyclopentadienyl)iridium(II)]; P-O and P,O,O% chelating ligands; Demethylation from phosphines
the complexes containing pentamethylcyclopentadienyl
or arene groups. Bis[dichloro(h6-arene) ruthenium(II)]
readily reacted with (2,6-dimethoxyphenyl)diphenyl-
1. Introduction
The chemistry of tris(2,4,6-trimethoxyphenyl)phos-
phine (TMPP) bearing the methoxy groups at the 2, 4
and 6-positions of the phenyl groups has been per-
formed by Dunbar’s groups [1]. This phosphine under-
goes demethylation from methoxy groups to form
various coordination modes. Tris(2,6-dimethoxyphenyl)-
phosphine (TDMPP), being less basic than TMPP ex-
hibits similar reaction behaviors. We have been inter-
ested in interactions of this and related phosphines with
phosphine
(MDMPP),
bis(2,6-dimethoxyphenyl)-
phenylphosphine (BDMPP), or TDMPP to give various
type of complexes bearing k1-P, k2(P,O) or k3(P,O,O%)
coordinations, depending on hydrocarbon ligands,
phosphines and reaction conditions [2]. We reported
that the reaction of bis[dichloro(h5-pentamethyl cy-
clopentadienyl)rhodium(III)] with MDMPP afforded
Cp*RhCl2(MDMPP-P) or Cp*RhCl(MDMPP-k2P,O)
(Cp*=h5-C5Me5; MDMPP-k2P,O=PPh2(C6H3-2-O-
6-MeO) [3]. We report the reactions of bis[dichloro(h5-
pentamethylcyclopentadienyl)iridium(III)], isoelectronic
* Corresponding author. Fax: +81-474-75-1855.
E-mail address: yamamoto@chem.sci.toho-u.ac.jp (Y. Yamamoto)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00271-5

50
Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
Table 1
Crystal data of [Cp*IrCl(BDMPP-P,O’)] 3b, [Cp*IrCl(TDMPP-P,O,O¦)] 4c, [Cp*IrCl(BDMPP-P,OMe)][PF6] 5b and [Cp*IrCl(BDMPP-
P,OMe)][PF6] 5c·CHCl3
Compound
3b
4c
5b
5c·CHCl3
Formula
Molecular weight
Color
C31H35ClO4PIr
730.26
Yellow
C32H36O6PIr
739.83
Yellow
C32H38ClO4P2F6Ir
890.26
Orange
C35H43P2O6Cl4F6Ir
1069.69
Orange
Crystal dimensions (mm)
Crystal system
Space group
0.40×0.30×0.20
Monoclinic
P21/n (No.14)
0.30×0.20×0.20
Orthorhombic
Pbcn (No. 60)
0.20×0.20×0.10
Triclinic
0.40×0.20×0.20
Monoclinic
P21/n(No. 14)
(
P1 (No. 2)
Lattice parameters
,
a (A)
15.994(3)
10.471(2)
17.727(3)
90.0
94.12(1)
90.0
2961.3(8)
4
8
17.55(1)
21.22(3)
15.92(2)
90.0
90.0
90.0
5930(11)
8
8
1.657
46.12
2944
11.679(2)
15.389(4)
10.251(3)
103.92(2)
91.76(2)
105.15(2)
1717.4(7)
2
16
1.721
41.36
880
14.730(7)
18.753(2)
15.753(9)
90.0
105.45(5)
90.0
4149(6)
4
8
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Scan rate (° min−1
)
Dcalcd (g cm−3
)
1.638
46.99
1448
1.712
36.30
2120
v (cm−1
F(000)
)
No. of reflections
5524
5785
6050
7562
No. of data (I\3.0|(I))
4041
2307
3776
3039
No. of variables
343
0.032; 0.078
1.98
361
0.044; 0.045
1.25
415
0.046; 0.057
1.62
487
0.048;0.048
1.16
a
R; Rw
GOF b
a R=SꢀꢀFoꢀ−ꢀFcꢀꢀ=SꢀFoꢀ and Rw=[S w(ꢀFoꢀ−ꢀFcꢀ)2=S wꢀFoꢀ ] (w=1/|2(Fo)).
2 1/2
b GOF=[Sw(ꢀFoꢀ−ꢀFcꢀ)2=S(No−Nv)]1/2, where No=number of data, Nv=number of variables.
Scheme 1.

Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
51
Scheme 2.
to ruthenium(II) and rhodium(III) complexes with
TDMPP, BDMPP or MDMPP and of the resulting
products with Lewis bases.
reduced pressure and the residue was chromatographed
on alumina. Yellow eluate with CH2Cl2 was concen-
trated to ca. 3 ml and hexane was added to give yellow
crystals of [Cp*IrCl(MDMPP-k2P,O)] 3a (57 mg,
41.7%). IR (Nujol): 1588, 1541 (P,O chelate) cm−1
.
2. Experimental
1H-NMR(CDCl3): l 1.51 (d, JPH=2.0 Hz, Cp*, 15H),
3.37 (s, MeO, 3H), 5.8–7.9 (m, Ph, 13H) ppm. 31P{1H}-
NMR (CDCl3): l 28.3 (s, 1P) ppm. Anal. Calc. for
C29H31O2ClPIr: C, 51.96; H, 4.66. Found: C, 51.65; H,
4.51.
All reactions were carried out under nitrogen atmo-
sphere.
Bis[dichloro(h5-pentamethyl
cyclopentadi-
enyl)iridium(III)] ([Cp*IrCl2]2) 1 was prepared by
refluxing a mixture of IrCl4·3H2O and pentamethylcy-
clopentadiene in MeOH. Phosphines [4] (MDMPP,
BDMPP and TDMPP) and isocyanides [5] (xylyl iso-
cyanide (XylNC) and mesityl isocyanide (MesNC))
were prepared according to the literature. p-TosCH2NC
was available commercially. Benzene, CH2Cl2 and other
solvents were distilled over CaH2. The infrared and
electronic absorption spectra were measured on FT/IR-
5300 and U-best 30 spectrometers, respectively. NMR
spectroscopy was carried out on a Bruker AC250.
1H-NMR spectra were measured at 250 MHz and
31P{1H}-NMR spectra were measured using 85%
H3PO4 as an external reference. The FAB mass spectra
were measured on a JMS-DX300 spectrometer.
2.2. Reaction of 1 with BDMPP
2.2.1. At room temperature in MeOH
A mixture of 1 (50 mg, 0.063 mmol) and BDMPP
(50.4 mg, 0.132 mmol) was stirred in MeOH (10 ml) at
r.t. After 80 min, the solvent was removed to dryness
and the residue was crystallized from CH2Cl2 and ben-
zene to yield colorless crystals (10 mg), identified as
phosphonium salt BDMPP·MeCl. The mother liquor is
2.1. Reaction of 1 with MDMPP
2.1.1. At room temperature
A mixture of 1 (70 mg, 0.088 mmol) and MDMPP
(57 mg, 0.174 mmol) was stirred in CH2Cl2 (10 ml) at
room temperature (r.t.). After 80 min, the solvent was
removed to ca. 3 ml and diethyl ether was added to give
orange crystals of [Cp*IrCl2(MDMPP-P)] 2a (43.8 mg,
34.9%). IR (Nujol): 1580 cm−1. UV–vis (CH2Cl2): umax
1
324, 295 nm. H-NMR (CDCl3): l 1.24 (s, Cp*, 15H),
3.28 (s, MeO, 6H), 7.1–7.5 (m, Ph, 13H) ppm. 31P{1H}-
NMR(CDCl3): l −4.67 (s, 1P) ppm. Anal. Calc. for
C30H34O2Cl2PIr: C, 50.00; H, 4.76. Found: C, 50.63; H,
4.84.
2.1.2. At reflux
A solution of 1 (81.0 mg, 0.102 mmol) and MDMPP
(74 mg, 0.23 mmol) in methanol (15 ml) was refluxed
for 3 h. The solvent was removed to dryness under
Fig. 1. The molecular structure of 3b (hydrogen atoms omitted for
clarity).

52
Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
Table 2
,
Selected bond lengths (A) and angles (°) of [Cp*IrCl(BDMPP-P,O%)] 3b
Complex
IrꢀP(1)
P(1)ꢀC(11)
O(2)ꢀC(12)
2.311(3)
1.80(1)
1.38(1)
IrꢀCl(1)
C(11)ꢀC(16)
O(3)ꢀC(23)
2.399(3)
1.41(2)
1.34(1)
IrꢀO(1)
O(1)ꢀC(16)
O(4)ꢀC(19)
2.084(8)
1.32(1)
1.38(2)
P(1)ꢀIrꢀCl(1)
86.9(1)
99.9(4)
120.2(7)
111.3(5)
Cl(1)ꢀIrꢀO(1)
P(1)ꢀC(11)ꢀC(16)
IrꢀP(1)ꢀC(18)
C(11)ꢀPꢀC(26)
86.5(3)
115.2(8)
114.6(4)
103.4(5)
P(1)ꢀIrꢀO(1)
C(11)ꢀC(16)ꢀO(1)
IrꢀP(1)ꢀC(26)
82.8(2)
121(1)
120.6(4)
106.1(5)
IrꢀP(1)ꢀC(11)
IrꢀO(1)ꢀC(16)
C(11)ꢀP(1)ꢀC(18)
C(18)ꢀP(1)ꢀC(26)
chromatographed on alumina. Yellow eluate with
CH2Cl2 (containing a trace amount of acetone) was
concentrated to dryness and the residue was recrystal-
lized from CH2Cl2–hexane to give orange crystals of
[Cp*IrCl(BDMPP-k2P,O)] 3b (44.4 mg, 43.2%). FAB
mass: m/z 730 (M+), 695 (M–Cl+). IR (Nujol): 1588,
ppm. 31P{1H}-NMR(CDCl3): l 18.6 (s, 1P). Anal. Calc.
for C32H36O6PIr·1/2CH2Cl2: C, 51.49; H, 4.91. Found:
C, 51.42; H, 4.61.
2.4. Reaction of 1 with phosphines in the presence of a
PF6 anion
1
1555 (P,O chelate) cm–1. H-NMR (CDCl3): l 1.54 (d,
JPH=1.8 Hz, Cp*, 15H), 3.09 (s, MeO, 3H), 3.25 (s,
2.4.1. With MDMPP
MeO, 3H), 3.72 (s, MeO, 3H), 5.23 (s, CH2Cl2, 1H),
5.6–7.5 (m, Ph, 11H) ppm. 31P{1H}-NMR(CDCl3): l
12.1 (s, 1P). Anal. Calc. for C32H35O4ClPIr·1/2CH2Cl2:
C, 49.74; H, 4.62. Found: C, 49.65; H, 5.19.
A similar reaction was carried out at reflux in MeOH
to give 3b (67.3%).
A mixture of 1 (50 mg, 0.063 mmol) and NaPF6 (22
mg, 0.132 mmol) in acetone–CH2Cl2 (10:5 ml) was
stirred at r.t. After 0.5 h, MDMPP (43 mg, 0.132
mmol) was added and the solution was stirred for 2 h.
The solvent was removed to dryness and the residue
was extracted with CH2Cl2. Orange crystals of
[Cp*IrCl(MDMPP-s2P,OMe)][PF6] 5a (38.8 mg, 44%)
were obtained by recrystallization from CH2Cl2–diethyl
ether. IR (Nujol): 835 (PF6) cm−1. UV–vis (CH2Cl2):
umax 295 nm. 1H-NMR(CDCl3): l 1.50 (d, JPH=2.5
2.3. Reaction of 1 with TDMPP
2.3.1. At room temperature
A mixture of 1 (50 mg, 0.063 mmol) and TDMPP
(66.5 mg, 0.132 mmol) was stirred in CH2Cl2 (10 ml) at
r.t. After 80 min, the solvent was dried and the residue
was crystallized from benzene–hexane to give pale yel-
low TDMPP·MeCl (12.8 mg). The mother liquor was
concentrated to dryness and recrystallization of the
residue from CH2CH2–benzene–hexane gave yellow
crystals of 4c (49 mg, 44.2%).
2.3.2. At reflux in MeOH
A mixture of 1 (118 mg, 0.148 mmol) and TDMPP
(269 mg, 0.607 mmol) was refluxed in MeOH (10 ml)
for 3 h. The solvent was removed to dryness and the
residue was crystallized from CH2Cl2–benzene to yield
very pale yellow crystals (133 mg), identified as a
phosphonium salt TDMPP·MeCl. The mother liquor is
chromatographed on alumina. Yellow eluate with
CH2Cl2 (containing a trace amount of acetone) was
concentrated to dryness and the residue was recrystal-
lized from CH2Cl2–benzene–hexane to give yellow
crystals of [Cp*IrCl(TDMPP-k3P,O,O%)] 4c (77 mg,
35.2%). FAB mass: m/z 740 (M+). IR (Nujol): 1584,
1
1553 (P,O chelate) cm−1. H-NMR (CDCl3): l 1.51 (d,
JPH=1.8 Hz, Cp*, 15H), 3.45 (s, MeO, 6H), 3.50 (s,
Fig. 2. The molecular structure of 4c (hydrogen atoms omitted for
MeO, 6H), 3.25 (s, CH2Cl2, 1H), 5.6–7.5 (m, Ph, 9H)
clarity).

Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
53
Table 3
Selected bond lengths (A) and angles (°) of [Cp*Ir(TDMPP-P,O,O%)] 4c
,
IrꢀP(1)
2.281(3)
1.784(10)
1.79(1)
1.34(1)
1.39(1)
IrꢀO(1)
2.080(7)
1.41(1)
1.41(2)
1.38(1)
IrꢀO(5)
2.063(7)
1.32(1)
1.33(1)
1.35(1)
P(1)ꢀC(11)
P(1)ꢀC(26)
O(2)ꢀC(16)
O6ꢀC31
C(11)ꢀC(12)
C(26)ꢀC27
O3ꢀC19
O(1)ꢀC(12)
O(5)ꢀC(27)
O(4)ꢀC(23)
O1···O5
P(1)ꢀIrꢀO(1)
IrꢀP(1)ꢀC(11)
IrꢀO(1)ꢀC(12)
C(26)ꢀC(27)ꢀO(5)
C(11)ꢀP(1)ꢀC(18)
83.1(2)
101.2(3)
118.5(6)
121(1)
P(1)ꢀIrꢀO(5)
80.8(2)
113.4(7)
101.3(4)
120.1(7)
114.2(5)
O(1)ꢀIrꢀO(5)
85.1(3)
123.2(9)
112.1(9)
105.5(5)
120.6(4)
P(1)ꢀC(11)ꢀC(12)
IrꢀP(1)ꢀC(26)
IrꢀO(5)ꢀC(27)
C(18)ꢀP(1)ꢀC(26)
C(11)ꢀC(12)ꢀO(1)
P(1)ꢀC(26)ꢀC(27)
C(11)ꢀP(1)ꢀC(26)
IrꢀP(1)ꢀC(18)
112.0(5)
Hz, Cp*, 15H), ca 3.90 (b, MeO, 6H), 7.2–7.4 (m, Ph,
13H) ppm. 31P{1H}-NMR (CDCl3): l 24.7 (s, 1P),
−143.9 (sep. JPF=713 Hz) ppm. Anal. Calc. for
C30H34O2ClF6P2Ir: C, 43.40; H, 4.13. Found: C, 42.82;
H, 4.34.
and the extraction of the residue with CH2Cl2 and
addition of diethyl ether yielded yellow crystals of
[Cp*IrCl(MDMPP-P)(XylNC)][PF6] 6a (13.8 mg,
1
32.1%). IR (Nujol): 2160 (NꢁC), 839 (PF6) cm−1. H-
NMR (CDCl3): l 1.71 (d, JPH=2.0 Hz, Cp*, 15H),
2.06 (s, o-Me, 3H), 3.36 (s, MeO, 6H), 6.6–7.7 (m, Ph,
16H) ppm. 31P{1H}-NMR(CDCl3): l −11.4 (s, 1P),
−144 (sep. JPF=712 Hz, PF6, 1P). Anal. Calc. for
C39H43NO2P2F6ClIr: C, 48.72; H, 4.51; N, 1.46. Found:
C, 48.45; H, 4.61; N, 1.56. Analogously, yellow crystals
of [Cp*IrCl(MDMPP-P)(L)][PF6] (6b: L=MesNC,
68.1%; 6c: L=TosCH2NC, 22.3%; 6d: L=CO, 48.5%)
were obtained by using a corresponding Lewis base (L).
2.4.2. With BDMPP
According to a procedure similar to that described
above,
orange
crystals
of
[Cp*IrCl(BDMPP-
k2P,OMe)][PF6] 5b (59.8 mg, 50.9%) were prepared by
the reaction of 1 (50 mg, 0.063 mmol) and BDMPP (52
mg, 0.132 mmol) in the presence of NaPF6 (22 mg,
0.132 mmol). IR (Nujol): 840 (PF6) cm−1. UV–vis
1
(CH2Cl2): umax 288 nm. H-NMR(CDCl3): l 1.44 (d,
1
6b: IR (Nujol): 2160 (NꢁC), 839 (PF6) cm−1. H-NMR
J
PH=2.0 Hz, Cp*, 15H), ca. 3.55 (b, MeO, 12H),
(CDCl3): l 1.70 (d, JPH=2.0 Hz, Cp*, 15H), 2.01 (s,
o-Me, 6H), 2.28 (s, p-Me, 3H), 3.28 (s, MeO, 6H),
6.6–7.7 (m, Ph, 15H) ppm. 31P{1H}-NMR(CDCl3): l
−11.4 (s, 1P), −144 (sep. JPF=712 Hz, PF6, 1P).
6.6–7.6 (m, Ph, 11H) ppm. 31P{1H}-NMR (CDCl3): l
21.1 (s, 1P), −144 (sep. JPF=713 Hz) ppm. Anal.
Calc. for C33H37O4ClF6P2Ir: C, 43.17; H, 4.30. Found:
C, 42.61; H, 4.27.
2.4.3. With TDMPP
Orange complex 5c (68%) was obtained by using
KPF6. FAB mass: m/z 805 (M+). IR (Nujol): 835 (PF6)
1
cm−1. H-NMR(CDCl3): l 1.44 (d, JPH=2.5 Hz, Cp*,
15H), 3.10 (s, MeO, 3H), 3.21 (s, MeO, 3H), 3.34 (s,
MeO, 3H), 3.50 (s, MeO, 3H), 3.72 (s, MeO, 3H), 4.56
(s, MeO, 3H), 6.3–7.5 (m, Ph, 9H) ppm. 31P{1H}-NMR
(CDCl3): l −7.08 (s, 1P), −144 (sep. JPF=713 Hz)
ppm. Anal. Calc. for C34H42O6ClF6P2Ir: C, 43.08; H,
4.46. Found: C, 43.12; H, 4.41.
Complex 5c was refluxed in MeOH for 2 h, and the
work-up of the reaction mixture recovered the starting
material.
2.5. Reaction of 2a with Lewis base in the presence of
NaPF6
The representative reaction is described. A mixture of
2a (30 mg, 0.045 mmol) and NaPF6 (7.6 mg, 0.045
mmol) in acetone–CH2Cl2 (4:4 ml) was stirred for 0.5 h
at r.t. and xylyl isocyanide (5.9 mg, 0.045 mmol) was
added. After 1.5 h, the solvent was removed to dryness
Fig. 3. The molecular structure of 5b (a PF6 anion and hydrogen
atoms omitted for clarity).

54
Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
C39H43NO4P2F6ClSIr: C, 45.68; H, 4.23; N, 1.37.
Found: C, 45.99; H, 4.07; N, 1.44. 6d: IR (Nujol): 2047
1
(NꢁC), 835 (PF6) cm−1. H-NMR (CDCl3): l 1.79 (d,
J
PH=2.5 Hz, Cp*, 15H), 3.35 (bs, MeO, 6H), 6.7–7.8
(m, Ph, 13H) ppm. 31P{1H}-NMR(CDCl3): l −12.9 (s,
1P), −144 (sep. JPF=712 Hz, PF6, 1P) Anal. Calc. for
C31H34O3P2F6ClIr: C, 47.42; H, 4.36. Found: C, 47.78;
H, 4.55.
Complex 6a (41.3 mg, 85.8%) was prepared from 5a
(42 mg, 0.050 mmol) and XylNC (10 mg, 0.076 mmol)
in CH2Cl2 (10 ml).
2.6. Crystal structure determination
Complexes (3b, 4c and 5b) were recrystallized from
CH2Cl2–ether. Complex 5c·CHCl3 was recrystallized
from CHCl3–ether. Data collection was carried out by
an AFC5S-Rigaku automatic diffractometer (26°C,
Mo–Ka radiation, graphite monochromator, u=
,
0.71069 A). Cell constants were determined from 20
high-angle reflections. The crystal parameters along
with data collection are summarized in Table 1. Intensi-
ties were measured by the 2q−ꢀ scan method and
corrected for Lorentz and polarization effects.
Throughout the data collection the intensities of the
three standard reflections were measured every 200
reflections as a check of the stability of the crystals and
any decay was not observed. Semiempirical absorption
correction („-scan method) was made. Atomic scatter-
ing factors were taken from the usual tabulation of
Cromer and Waber [6]. Anomalous dispersion effects
were included in Fcalc [7]; the values of Df % and Df ¦
were those of Creagh and McAuley [8]. All calculations
Fig. 4. The molecular structure of 5c (a PF6 anion and hydrogen
atoms omitted for clarity).
Anal. Calc. for C40H45NO2P2F6ClIr: C, 49.25; H, 4.65;
N, 1.44. Found: C, 49.45; H, 4.77; N, 1.49. 6c: IR
.
(Nujol): 2207 (NꢁC), 841 (PF6) cm−1 1H-NMR
(CDCl3): l 1.61 (d, JPH=2.5 Hz, Cp*, 15H), 2.47 (s,
p-Me, 3H), 3.28 (s, MeO, 6H), 4.71 (center of an AB
type quartet, J=15.4 Hz, 2H), 6.6–7.6 (m, Ph, 17H)
ppm. 31P{1H}-NMR(CDCl3): l −11.4 (s, 1P), −144
(sep.
JPF=712 Hz, PF6, 1P). Anal. Calc. for
Table 4
,
Selected bond lengths (A) and angles (°) of [Cp*IrCl(BDMPP-P,OMe)][PF6] 5b
IrꢀP(1)
P(1)ꢀC(11)
O(2)ꢀC(16)
2.319(3)
1.81(1)
1.38(1)
IrꢀCl(1)
C(11)ꢀC(12)
O(3)ꢀC(20)
2.364(3)
1.40(2)
1.35(1)
IrꢀO(1)
O(1)ꢀC(12)
O(4)ꢀC(26)
2.242(8)
1.42(1)
1.41(1)
P(1)ꢀIrꢀCl(1)
86.9(1)
102.8(4)
122.3(6)
111.9(5)
Cl(1)ꢀIrꢀO(1)
P(1)ꢀC(11)ꢀC(12)
IrꢀP(1)ꢀC(19)
82.4(2)
121.3(8)
115.5(3)
100.7(5)
P(1)ꢀIrꢀO(1)
C(11)ꢀC(12)ꢀO(1)
IrꢀP(1)ꢀC(27)
79.8(2)
113(1)
119.1(3)
105.9(5)
IrꢀP(1)ꢀC(11)
IrꢀO(1)ꢀC(12)
C(11)ꢀP(1)ꢀC(19)
C(11)ꢀP(1)ꢀC(27)
C(19)ꢀP(1)ꢀC(27)
Table 5
,
Selected bond lengths (A) and angles (°) of [Cp*ICl(TDMPP-P,OMe)][PF6]·CHCl3 5c
IrꢀP(1)
2.353(3)
1.81(1)
1.35(1)
1.36(1)
IrꢀCl(1)
2.386(3)
1.38(2)
1.39(1)
1.33(1)
IrꢀO(1)
O(1)ꢀC(12)
O(4)ꢀC(24)
2.320(8)
1.40(1)
1.34(1)
P(1)ꢀC(11)
O(2)ꢀC(16)
O(5)ꢀC(28)
C(11)ꢀC(12)
O(3)ꢀC(20)
O(6)ꢀC(32)
P(1)ꢀIrꢀCl(1)
88.1(1)
104.1(4)
120.6(6)
100.7(5)
Cl(1)ꢀIrꢀO(1)
P(1)ꢀC(11)ꢀC(12)
IrꢀP(1)ꢀC(19)
81.0(2)
120.2(10)
121.2(4)
110.3(6)
P(1)ꢀIrꢀO(1)
C(11)ꢀC(12)ꢀO(1)
IrꢀP(1)ꢀC(27)
77.3(2)
116(1)
109.5(4)
110.2(5)
IrꢀP(1)ꢀC(11)
IrꢀO(1)ꢀC(12)
C(11)ꢀP(1)ꢀC(19)
C(11)ꢀP(1)ꢀC(27)
C(19)ꢀP(1)ꢀC(27)

Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
55
Scheme 3.
were performed using the teXsan crystallographic soft-
ware package of Molecular Structure Corporation [9].
The structures were solved by Patterson methods
(DIRDIF92). The positions of iridium and other non-
hydrogen atoms were anisotropically refined by full-
matrix least-squares methods. Hydrogen atoms were
calculated at the ideal positions with the CꢀH distance
and 3.72 ppm consisting of a 1:1:1 ratio for the MeO
groups, suggesting that all methoxy groups are inequiv-
alent, probably resulted in steric demand. The X-ray
analysis indicated that the molecule has two chiral
centers (Ir and P atoms) (Fig. 1) (vide infra). A priority
order of the ligands is Cp* ring\Cl\P\O for a
metal
center
and
Ir\2-O–6-MeOC6H3\2,6-
,
of 0.95 A. Maximum and minimum peaks in the final
(MeO)2C6H3\Ph for a P center [2,10]. Fig. 1 showed
that the molecule is an IrRPR/IrSPS pair. Complex 3b
has a similar stereochemistry in solution and in the
solid state, whereas the ruthenium analog [(h6-
arene)RuCl(BDMPP-k2P,O)] is consistent of a RuRPR/
RuSPS pair in the solid state and of two pairs of
diastereomers in solution [2] (Table 2).
−3
,
difference Fourier maps were +0.74 and −0.86 e A
−3
,
for 3b, +1.16 and −0.90 e A
for 4c, and +0.91
for 5b, and +0.85 and −0.77 e
−3
,
and −0.84 e A
−3
,
A
for 5c·CHCl3, respectively.
When 1 was treated with much bulky TDMPP at r.t.
or at reflux in MeOH, the reaction underwent demethy-
lation of two methyl groups from the ortho-methoxy
groups to form yellow complex [Cp*Ir(TDMPP-
k3P,O,O%)] 4c, in addition to TDMPP·MeCl. Mono-
demethylated complex such as 3 was not obtained even
at r.t., due to sterically crowded TDMPP. It was confi-
rmed by an X-ray analysis that TDMPP acted as a
3. Results and discussion
3.1. Reactions with phosphines
The overall reactions are depicted in Schemes 1 and
2. Complex 1 reacted with MDMPP at r.t. to give an
orange complex 2a formulated as [Cp*IrCl2(MDMPP-
1
P)]. In the H-NMR spectrum the Cp* protons showed
1
a doublet at l 1.43 ppm due to a coupling with 31P
atom. The 31P{1H}-NMR spectrum appeared at l −
4.67 ppm, shifting upfield in comparison with that
found in the rhodium analog [3]. The IR spectrum
showed only one band (1580 cm−1) in the range from
1500 to 1600 cm−1, suggesting the presence of the h1-P
coordination [2]. When the reaction was refluxed in
MeOH, one of the ortho-methoxy groups in MDMPP
was demethylated to give [Cp*IrCl(MDMPP-k2P,O)]
3a with a P,O-chelating phosphine. In the IR spectrum
two peaks (1586 and 1555 cm−1) were found in the
range of 1600–1500 cm−1, suggesting the presence of a
P,O(s-) bidentate ligand [2].
P,O,O% tridentate ligand (Fig. 2). The H-NMR spec-
trum showed two singlets at l 3.43 and 3.50 ppm
consisting of a 1:1 intensity ratio and was in agreement
with the structure of solid state. Two absorption bands
appeared in the range from 1500 to 1600 cm−1 in the
infrared spectrum, again suggesting the presence of a
(P,s-O) coordination (Table 3).
Demethylation is assumed to proceed through a four-
centered intermediate which was suggested in the reac-
tions of [(h6-arene)RuCl2]2 with TDMPP [2].
Reaction of 1 with BDMPP in MeOH at r.t. under-
went demethylation from BDMPP to afford an orange
complex [Cp*IrCl(BDMPP-k2P,O)] 3b. The 31P{1H}-
NMR spectrum showed the only one resonance at l
1
12.1 ppm, suggesting the absence of isomers. The H-
NMR spectrum showed three singlets at l 3.09, 3.25,

56
Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
Reaction of 1 with MDMPP, BDMPP or TDMPP in
3
,
(2.353(3) A), due to difference between a k (P,O,O%)
the presence of a PF6 anion readily gave a salt-like
tridentate ligand and a k2(P,O) bidentate one. The IrꢀO
complex [Cp*IrCl(L-k2P,OMe)][PF6]
5
(a: L=
,
|-bond lengths in 3b (2.084(8) A for IrꢀO(1)) and 4c
MDMPP; b: L=BDMPP; c=TDMPP). The FAB
mass spectroscopy of 5c showed the m/z value of 803
which is in agreement with a molecular peak of a
cationic moiety. The PF6 group was found by a strong
band at ca. 840 cm−1. X-ray crystal analyses of 5b and
5c showed that phosphine acted as a P,O bidentate
ligand (Figs. 3 and 4). In the 1H-NMR spectra of
complexes 5a and 5b the methoxy protons showed only
one broad signal at l ca. 3.8 ppm, suggesting a rapid
exchange between free and coordinated MeO groups.
The weak IrꢀO(Me) interaction was revealed by the fact
that addition of [NEt3(CH2Ph)]Cl to a solution of 5a
regenerated 2a (Eq. (1)). A similar behavior has been
observed in the rhodium analog [Cp*RhCl(MDMPP-
k2P,OMe)][PF6] [3] (Tables 4 and 5).
,
,
(2.080(7) A for IrꢀO(1) and 2.063(7) A for IrꢀO(5)) are
shorter than the Ir’O(1) coordination lengths of
,
2.242(8) for 5b and 2.320(8) A for 5c depending on
bonding modes. Especially, these deferences were traced
back the IrꢀCl lengths for 3b, 5b and 5c; IrꢀCl length
(2.399(3) A) for 3b is slightly longer than those
(2.364(3) A and 2.386(3) A) for 5b and 5c. The
O(1)ꢀC(12) bond lengths of 1.42(1) A for 5b and of
1.40(1) for 5c were longer than those found in the
,
,
,
,
corresponding
OꢀC(aromatic)
lengths
in
3b
,
,
(O(1)ꢀC(16)=1.32A) and 4c (O(1)ꢀC(12)=1.32 A and
O(5)ꢀC(27)=1.33 A); this elongation being arised from
,
coordination of lone pair electrons to the metal atom.
The PꢀIrꢀO(|-bond) bite angles are in the range 83–
80°, being narrower than PꢀIrꢀCl (ꢀ87°), OꢀIrꢀCl
(87–82°) and OꢀIrꢀO (ꢀ85°) angles. The PꢀIrꢀO bite
angle-range (ꢀ82°) in five-membered rings appears to
be common to compounds with P,O chelating ligands
derived by demethylation from MDMPP, BDMPP or
TDMPP [2,3]; 82.50(9)° for [(h6-1,2,3,4-Me4C6H2)-
RuCl(MDMPP-k2P,O)], 82.2(2)° for [(h6-p-cymene)-
RuCl(BDMPP-k2P,O)], [(h6-arene)RuCl(TDMPP-k3P,-
O,O%)] (80.1–82.9°) ca. 82° for [Cp*RhCl(MDMPP-
k2P,O)] and [Cp*Rh(MDMPP-k2P,O)(L)][PF6] (L=p-
TosCH2NC).
In complexes of bis(diphenylphosphino)ethane con-
structing the five-membered chelating ring the PꢀMꢀP
bite angles are approximatly 85° [11] and are wider
than the average PꢀMꢀO bite angle of 82° in P,O-
chelating complexes, depending on the atomic radii;
0.74 A for an O atom and 1.10 A for a P atom. The
PꢀIr’O bite angles were narrower than those found in
PꢀIrꢀO (|-bond).
[Cp*IrCl(MDMPP-k2P,OMe)][PF6]
[NEt (CH Ph)]Cl
2
ꢀꢀꢀ3ꢀꢀꢀꢀꢀꢀꢀꢂCp*IrCl2(MDMPP-P)
(1)
1
The H-NMR spectrum of 5c showed six sharp sin-
glets at l 3.10, 3.21, 3.34, 3.50, 3,72 and 4.56 ppm for
six methoxy groups, showing the absence of an ex-
change between free and coordinated methoxy groups.
The last one is probably assigned for a coordinated
methoxy group. The inequivalence for six methoxy
groups showed a characteristic feature of bulky phos-
phine. When 5 was refluxed in methanol, the starting
compound was recovered quantitatively. The elonga-
,
tion of an Ir’O coordination length by ca. 0.25 A in
comparison with the PꢀO |-bond length prevented
approach between Cl and Me groups to undergo a
second demethylation.
,
,
3.2. Reactions with Lewis bases
Remarkable difference in complexes 5b and 5c was
observed around the iridium metals; the bond distances
IrꢀA (A=P, Cl, O) of 5c are longer than those of 5b,
due to the steric demand of TDMPP ligand
Complex 2a readily reacted with Lewis bases (L) such
as isocyanides or CO in the presence of a PF6 anion to
afford yellow complex formulated as [Cp*Ir(MDMPP-
P)(L)][PF6] 6 (Scheme 3). Complex 6 showed a sharp
band at ca. 2100 cm−1 due to w(NꢁC) or w(CꢁO) in the
infrared spectra. The molecule is assumed to have a
piano-stool structure surrounded by Cp*, Cl, phos-
4. Conclusions
1
phine and isocyanide (or CO). The H-NMR spectra
supported the proposed structure. In the 31P{1H}-NMR
spectra the signal appeared at l ca. −12 ppm, again
indicating h1-P coordination. Complex 6 was also pre-
pared by direct treatment of a salt-like complex 5a with
Lewis base. Similar reactions have been noted in
rhodium analogs [3].
MDMPP acted as a monohapto ligand in the reac-
tion with [Cp*IrCl2]2 1 at r.t., whereas a demethylation
of one methyl group for BDMPP occurred to give the
complex with a k2(P,O) chelating ligand. For much
bulky TDMPP two methyl groups were easily elimi-
nated to form the complex with a k3(P,O,O%) tridentate
ligand. These reactions depend on steric demand of
phosphines rather than basicity. For MDMPP,
BDMPP and TDMPP cationic complexes with a
P,OMe coordination mode were obtained in the pres-
ence of a PF6 anion, independent of phosphines.
3.3. X-ray structural analyses
,
The IrꢀP length of 2.281(3) A in 4c is shorter than
,
,
those for 3b (2.311(3) A), 5b (2.319(3) A) and 5c

Y. Yamamoto et al. / Journal of Organometallic Chemistry 587 (1999) 49–57
57
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1341 and therin.
5. Supplementary material
Listings of data collection, positional coordinates,
anisotropic thermal parameters, bond lengths and an-
gles (49 pages) are available from Y. Yamamoto on
request.
Acknowledgements
[2] (a) Y. Yamamoto, R. Sato, F. Matsuo, C. Sudoh, T. Igoshi,
Inorg. Chem. 35 (1996) 2329. (b) Y. Yamamoto, T. Tanase, C.
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The authors wish to thank Professor Shigetoshi
Takahashi and Ms Fumie Takei in The Institute of
Scientific and Industrial Research, Osaka University for
measurement of FAB mass spectra.
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