(η5-Pentamethylcyclopentadienyl)rhodium(III) complexes bearing η1-P and η2-phosphino-phenoxide coordinations derived from (2,6-dimethoxyphenyl)d iphenylphosphine: Their preparation and reactions with Lewis bases

Article abstract of DOI:10.1016/S0022-328X(98)00523-3

Reaction of [Cp*RhCl₂]₂ with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) gave Cp*RhCl₂(MDMPP-P) 2 and Cp*RhCl(MDMPP-P,O) 5, depending on the reaction conditions. Treatment of 2 with NaPF₆ formed the O-coordination complex, [Cp*RhCl(MDMPP-P,OMe)](PF₆) 3. Complex 3 was reconverted to 2 by treatment with [N(CH₂Ph)Et₃]Cl. Reactions of 3 with isocyanide, carbon monoxide or P(OCH₂)₃CMe eliminated the O-coordination to give the corresponding complexes [Cp*RhCl(MDMPP-P)(L)](PF₆) 4 (L=CO (a), 2,6-Me₂C₆H₃NC (b), p-TosCH₂NC (c), and P(OCH₂)₃CMe) (d). Complex 5 reacted with Lewis bases (L) in the presence of NaPF₆ to produce [Cp*Rh(MDMPP-P,O)(L)](PF₆) 6 and could be also obtained from 3 and MDMPP. The CO ligand of 4a or 6a was labile and was replaced with isocyanide or phosphine to produce the corresponding complexes, whereas its reverse reaction did not occur. Conversion of 4d to 6d was also observed, but conversion from 4 to 6 did not occur in other complexes. X-ray analyses of 2, 4a, 5 and 6a·C₆H₆ were performed and showed that the complexes have the piano-stool structure; 2: triclinic, P1 (no. 2), a=10.639(3), b=15.965(3), c=8.800(3) A, α=94.43(2), β=103.75(3), γ=88.62(2)°, V=1447.4(7) A³, Z=2, R=0.039, R_w=0.042; 4c (L=p-TosCH₂NC): orthorhombic, Pna2₁ (no. 33), a=26.817(4), b=17.662(5), c=8.673(4) A, V=4108(1) A³, Z=4, R=0.040, R_w=0.042; 5: orthorhombic, Pbca (no. 61), a=8.212(8), b=17.808(10), c=35.96(1) A, V=5259(4) A³, Z=8, R=0.040, R_w=0.042; 6a·C₆H₆ (L=CO): monoclinic, C2/c (no. 15), a=33.29(2), b=8.567(5), c=29.26(3) A, β=124.51(3)°, V=6877(7) A³, Z=8, R=0.040, R_w=0.042.

Full text of DOI:10.1016/S0022-328X(98)00523-3

Journal of Organometallic Chemistry 561 (1998) 157–165
(p5-Pentamethylcyclopentadienyl)rhodium(III) complexes bearing p1-P
and p2-phosphino-phenoxide coordinations derived from
(2,6-dimethoxyphenyl)diphenylphosphine: their preparation and
reactions with Lewis bases
Xiao-Hong Han, Yasuhiro Yamamoto *
Department of Chemistry, Faculty of Science, Toho Uni6ersity, Miyama 2-2-1, Funabashi, Chiba 274, Japan
Received 24 December 1997; received in revised form 25 February 1998
Abstract
Reaction of [Cp*RhCl2]2 with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) gave Cp*RhCl2(MDMPP-P) 2 and
Cp*RhCl(MDMPP-P,O) 5, depending on the reaction conditions. Treatment of 2 with NaPF6 formed the O-coordination
complex, [Cp*RhCl(MDMPP-P,OMe)](PF6) 3. Complex 3 was reconverted to 2 by treatment with [N(CH2Ph)Et3]Cl. Reactions
of 3 with isocyanide, carbon monoxide or P(OCH2)3CMe eliminated the O-coordination to give the corresponding complexes
[Cp*RhCl(MDMPP-P)(L)](PF6) 4 (L=CO (a), 2,6-Me2C6H3NC (b), p-TosCH2NC (c), and P(OCH2)3CMe) (d). Complex 5
reacted with Lewis bases (L) in the presence of NaPF6 to produce [Cp*Rh(MDMPP-P,O)(L)](PF6) 6 and could be also obtained
from 3 and MDMPP. The CO ligand of 4a or 6a was labile and was replaced with isocyanide or phosphine to produce the
corresponding complexes, whereas its reverse reaction did not occur. Conversion of 4d to 6d was also observed, but conversion
from 4 to 6 did not occur in other complexes. X-ray analyses of 2, 4a, 5 and 6a·C6H6 were performed and showed that the
˚
complexes have the piano-stool structure; 2: triclinic, P1 (no. 2), a=10.639(3), b=15.965(3), c=8.800(3) A, h=94.43(2),
3
˚
i=103.75(3), k=88.62(2)°, V=1447.4(7) A , Z=2, R=0.039, Rw=0.042; 4c (L=p-TosCH2NC): orthorhombic, Pna21 (no.
33), a=26.817(4), b=17.662(5), c=8.673(4) A, V=4108(1) A , Z=4, R=0.040, Rw=0.042; 5: orthorhombic, Pbca (no. 61),
a=8.212(8), b=17.808(10), c=35.96(1) A, V=5259(4) A , Z=8, R=0.040, Rw=0.042; 6a·C6H6 (L=CO): monoclinic, C2/c
(no. 15), a=33.29(2), b=8.567(5), c=29.26(3) A, i=124.51(3)°, V=6877(7) A , Z=8, R=0.040, Rw=0.042. © 1998 Elsevier
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Science S.A. All rights reserved.
Keywords: (2,6-Dimethoxyphenyl)diphenylphosphine; Bis[dichloro(pentamethylcyclopentadienyl) rhodium(II); Crystal structures;
P–O chelating ligand
1. Introduction
alkoxy groups at the 2- and 6-positions are one of the
categories in the ether–phosphine species. Tris(2,4,6-
trimethoxyphenyl)phosphine (TMPP) has produced the
complexes containing a variety of coordination modes
such as (p1-P), (p2-P,OMe), (p2-P,O), and (p3-
P,O,OMe) [2], because of its high basicity and large
cone angle [3]. Tris(2,6-dimethoxyphenyl)phosphine
(TDMPP) and its related phosphines such as bis(2,6-
dimethoxyphenyl)phenylphosphine (BDMPP) and (2,6-
dimethoxyphenyl)diphenylphosphine (MDMPP) also
showed interesting chemical behavior. Recently we have
The introduction of ether–phosphine species, instead
of classical phosphines, plays an important role as an
anchor to prepare intramolecular solvent complexes
which are much more stable than simple solvent
molecules [1]. A weak metal–oxygen bond provides as
a condition of valuable precursors in catalytically-oper-
ating process. Aromatic phosphines containing the
* Corresponding author. Fax: +81 474 751855.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00523-3

158
X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
carried out the systematic reactions of bis[dichloro(p6-
arene)ruthenium(II)] with these phosphines (TDMPP,
BDMPP, and MDMPP) [4]. We reported that the
reaction with TDMPP gave the complexes (p6-
arene)Ru[P(2-O-6-MeOC6H3)2(2,6-(MeO)2C6H3)] hav-
ing new type of trihapto-(P,O,O) coordination and that
the reaction with BDMPP or MDMPP formed the
for C30H34O2Cl2PRh: C, 57.07; H, 5.43. Found: C,
56.65; H, 5.12%.
2.2. Reaction of 2 with NaPF6
To a solution of 2 (125 mg, 0.198 mmol) in CH2Cl2
(10 ml)/acetone (5 ml) was added NaPF6 (60 mg, 0.357
mmol) at r.t. After 4 h, the solvent was removed and
the residue was extracted with CH2Cl2. The solvent was
removed to ca. 3 ml and hexane was added to give red
crystals of [Cp*RhCl(MDMPP-P,OMe)](PF6) 3 (132
dihapto-(P,O)
MeOC6H3)(2,6-(MeO)2C6H3)Ph] and the monohapto-
(P) one,
(p6-arene)RuCl2[PPh2(2,6-(MeO)2C6H3)],
complex,
(p6-arene)RuCl[P(2-O-6-
respectively. Complexes prepared in these reactions
have been obtained as a result of the direct formation.
Our research was extended to bis[dichloro(p5-pen-
tamethylcyclopentadienyl)rhodium(III)] [Cp*RhCl2]2 1,
which has an isoelectronic structure. In the reactions of
1 with MDMPP, we could isolate the (p1-P), (p2-
P,OMe) and (p2-P,O) coordinated complexes of (p5-
pentamethylcyclopentadienyl)rhodium(III). We found
that the stepwise conversion from the (p1-P) to the
phosphino–phenoxido complexes occurred and these
complexes showed versatile reactivities to Lewis bases.
Here we wish to report the preparations and reactions
of monohapto-(p1-P) and dihapto-(P,OMe) and (P,O)
chelated complexes derived from a MDMPP ligand.
mg, 86%). IR (nujol): 1585, 1537, 835 (PF6) cm−1
.
UV–vis (CH2Cl2): umax 365, 285 nm. 1H-NMR
(CDCl3): l 1.50 (d, JPH=3.0 Hz, C5Me5), 3.88 (s,
OMe), 6.7–7.7 (m, Ph) ppm. 31P{1H}-NMR (CDCl3):
l 37.8 (d, JRhP=146.5 Hz), −143.9 (sep, JPF=708.8
Hz) ppm. Anal. Calc. for C30H34O2ClF6P2Rh: C, 48.63;
H, 4.63. Found: C, 48.62; H, 4.32%.
This complex was also prepared from the stoichio-
metric reaction of 1 with MDMPP in the presence of
NaPF6.
2.3. Reaction of 3 with [(PhCH2)Et3N]Cl
A solution of 3 (16 mg, 0.022 mmol) and benzyltri-
ethylammonium chloride (4.6 mg, 0.025 mmol) in
CH2Cl2 (10 ml) was stirred at r.t. for 3 h. The precipi-
tate was filtered off and the solvent was removed to ca.
3 ml from the filtrate and ether was added to give 2
(6.42 mg, 78%).
2. Experimental
All reactions were carried out under nitrogen atmo-
sphere. Complex 1 [5], MDMPP [3], P(OCH2)3CMe [6],
and xylyl isocyanide [7] were prepared according to the
literature. p-TosCH2NC (p-Tos =p-MeC6H4SO2) and
(p-tolyl)3P (p-tolyl=p-MeC6H4) were available com-
mercially. Toluene, CH2Cl2 and other solvents were
distilled over CaH2. The IR and electronic absorption
spectra were measured on FT/IR-5300 and U-best 30
spectrometers, respectively. NMR spectroscopy was
2.4. Reaction of 3 with CO
Carbon monoxide was bubbled for 3 min through
a solution of 3 (61.5 mg, 0.083 mmol) in CH2Cl2
(10 ml) at r.t. After the mixture had been stirred for
2 h, the solvent was removed under reduced pres-
sure, and the residue was recrystallized from CH2Cl2
and hexane to give orange crystals (44.3 mg, 86%)
of [Cp*RhCl(MDMPP-P)(CO)](PF6)·0.5CH2Cl2 4a·
0.5CH2Cl2. IR (nujol): 2071 (CꢀO), 1583, 835 (PF6)
1
carried out on a Bruker AC250. H-NMR spectra were
measured at 250 MHz using tetramethylsilane as an
internal reference and 31P{1H}-NMR spectra were mea-
sured at 100 MHz using 85% H3PO4 as an external
reference.
1
cm−1. UV–vis (CH2Cl2): umax 366, 286 nm. H-NMR
(CDCl3): l 1.50 (d, JPH=3.0 Hz, C5Me5), 3.88 (s,
OMe), 5.27 (s, CH2Cl2), 6.7–7.7 (m, Ph) ppm. 31P{1H}-
NMR (CDCl3): l 20.2 (d, JRhP=121.8 Hz), −144.0
2.1. Reaction of 1 with MDMPP
To a solution of 1 (82.8 mg, 0.134 mmol) in CH2Cl2
(15 ml) was added MDMPP (108.2 mg, 0.334 mmol) at
room temperature (r.t.). After the mixture was stirred
for 2 h, the solvent was removed to ca. 3 ml under
reduced pressure and hexane was added to the solution
to give dark red crystals of [Cp*RhCl2(MDMPP-P)] 2
(150.4 mg, 89%). IR (nujol): 1575 cm−1. UV–vis
(CH2Cl2): umax 404 (log m 3.94), 278 (log m 4.46) nm.
1H-NMR (CDCl3): l 1.15 (d, JPH=3.5 Hz, C5Me5),
3.28 (s, OMe), 6.4–7.7 (m, Ph) ppm. 31P{1H}-NMR
(CDCl3): l 23.6 (d, JRhP=150.9 Hz) ppm. Anal. Calc.
(sep,
JPF=708.8 Hz) ppm. Anal. Calc. for
C31.5H35O3ClF6P2Ru: C, 48.76; H, 4.55. Found: C,
48.85; H, 4.39%.
2.5. Reaction of 3 with xylyl isocyanide
Xylyl isocyanide (18.2 mg, 0.138 mmol) was added to
a solution of 3 (54.3 mg, 0.086 mmol) in CH2Cl2 (10
ml) at r.t. After the mixture had been stirred for 2 h,
the solvent was removed to ca. 3 ml in vacuo and
diethyl ether was added to give orange crystals (75.4

X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
159
mg, 98%) of [Cp*RhCl(MDMPP-P)(XylNC)](PF6) 4b.
UV–vis (CH2Cl2): umax 340 nm. IR (nujol): 2168
(NꢀC), 1581, 839 (PF6) cm−1 1H-NMR (CDCl3): l
2.8. Reactions of 4a with xylyl isocyanide or
P(OCH2)3CMe
.
1.69 (d, JPH=3.75 Hz, C5Me5), 2.11 (s, o-Me), 3.37 (s,
OMe), 6.7–7.8 (c, Ph) ppm. 31P{1H}-NMR (CDCl3): l
21.7 (d, JRhP=130.5 Hz), −144.0 (sep, JPF=708.8 Hz)
ppm. Anal. Calc. for C39H43O2NF6ClP2Rh: C, 53.71;
H, 4.94; N, 1.61. Found: C, 53.72; H, 4.95; N, 1.64%.
Complex 4c (20.5 mg, 65%) was prepared from the
reaction of 3 (25.3 mg, 0.034 mmol) with p-TosCH2NC
(9.4 mg, 0.045 mmol). UV–vis (CH2Cl2): umax 337 nm.
A CH2Cl2 solution of 4a and xylyl isocyanide or
P(OCH2)3CMe was stirred for 2 h at r.t. The work-up
of the mixture gave the corresponding 4b or 4d.
2.9. Reaction of 5 with CO
Carbon monoxide was bubbled through a mixture of
5 (171.7 mg, 0.237 mmol) and excess NaPF6 in CH2Cl2
(10 ml) and acetone (5 ml) for 3 min at r.t. and the
mixture was kept stirring for 2 h. The solvent was
removed in vacuo, the residue was extracted with
CH2Cl2. The solvent was removed to ca. 3 ml and
diethyl ether was added to yield red crystals of
[Cp*Rh(MDMPP-P,O)(CO)](PF6)·0.75CH2Cl2
IR (nujol): 2214 (NaC), 1581, 850 (PF6) cm−1 1H-
.
NMR (CDCl3): l 1.63 (d, JPH=3.75 Hz, C5Me5), 2.51
(s, p-Me), 3.33 (s, OMe), 4.68 (a center value of a AB
type, JAB=13.9 Hz, wAB=4.7 Hz), 6.6–8.1 (c, Ph)
ppm. 31P{1H}-NMR (CDCl3): l 22.0 (d, JRhP=126.9
Hz), −144.0 (sep, JPF=708.8 Hz) ppm. Anal. Calc.
for C39H43O4NSClF6P2Rh: C, 50.04; H, 4.63; N, 1.49.
Found: C, 49.98; H, 4.58; N, 1.37%.
6a·0.75CH2Cl2 (131.2 mg, 78%). umax 366, 286. IR
(nujol): 2089 (CꢀO), 1583, 1545, 839 (PF6) cm−1. H-
1
Complex 4d·0.75CH2Cl2 (24.9 mg, 73%) was pre-
pared from the reaction of 3 (28 mg, 0.038 mmol) with
P(OCH2)3CMe (10.7 mg, 0.079 mmol). UV–vis
(CH2Cl2): umax 339, 233 nm. IR (nujol): 2110 (NꢀC),
NMR (CDCl3): l 1.68 (d, JPH=4.0 Hz, C5Me5), 3.39
(s, MeO), 6.7–7.9 (m, Ph) ppm. 31P{1H}-NMR
(CDCl3): l 46.8 (d, JRhP=111.9 Hz), −140.0 (sep PF6,
J
C
PF=708.8
30.75H32.5O3Cl1.5F6P2Rh: C, 47.22; H, 4.15. Found: C,
47.83; H, 3.91%.
Hz)
ppm.
Anal.
Calc.
for
1
1583, 837 (PF6) cm−1. H-NMR (CDCl3): l 0.75 (s,
CMe), 1.55 (dd, JPH=3.5 Hz, JPH=6.0 Hz C5Me5),
3.34 (s, o-Me), 4.15 (c, OCH2), 5.27 (s, CH2Cl2), 6.6–
7.6 (m, Ph) ppm. 31P{1H}-NMR (CDCl3): l 19.02 (dd,
2.10. Reaction of 5 with P(OCH2)3CMe
JRhP=135.7 Hz, JPP=89.0 Hz), 114.0 (dd, JRhP
=
223.5 Hz, PP=89.0 Hz) ppm. Anal. Calc. for
C34.75H44.5O5Cl2.5F6P3Rh: C, 44.37; H, 4.77. Found:
C,44.76;H, 4.55%.
J
A sample of P(OCH2)3CMe (11 mg, 0.081 mmol) was
added to a solution of 5 (25 mg, 0.046 mmol) and an
excess of NaPF6 in CH2Cl2 (10 ml) and acetone (5 ml)
at r.t. After 2 h, the solvent was removed to dryness
and the residue was extracted with CH2Cl2. The solvent
was removed to ca. 3 ml and diethyl ether was added to
2.6. Reaction of 3 with MDMPP
A solution of 3 (10.8 mg, 0.015 mmol) and MDMPP
(7.1 mg, 0.021 mmol) in CH2Cl2 (15 ml) was stirred at
r.t. After 2 h, the solvent was removed to dryness and
the residue was crystallized from CH2Cl2/hexane to
yield reddish orange crystals of Cp*RhCl(MDMPP-
yield
orange
crystals
of
[Cp*Rh(MDMPP-
P,O){P(OCH2)3CMe}](PF6) 6d (18.7 mg, 51%). UV–
vis (CH2Cl2): umax 309 nm. IR (nujol): 1583, 1548, 839
(PF6) cm−1. H-NMR (CDCl3): l 0.60 (s, CMe), 1.53
1
(dd, JPH=3.0 Hz, JPH=5.0 Hz, C5Me5), 3.32 (s,
MeO), 3.82 (m, CH2), 6.0–7.6 (m, Ph). 31P{1H}-NMR
(CDCl3): l 47.4 (dd, JRhP=121.5 Hz, JPP=85.0 Hz,
MDMPP-P), 115.4 [dd, JRhP=230.7 Hz, JPP=85.0
Hz, (p-tol)3P], −143.8 (sep PF6, JPF=708.8 Hz). Anal.
Calc. for C33H40O5F6P3Rh: C, 47.96; H, 4.88. Found:
C, 47.70; H, 4.62%.
P,O) 5 (7.1 mg, 84%). IR (nujol): 1585, 1537 cm−1
.
UV–vis (CH2Cl2): umax 331, 400(sh) nm. 1H-NMR
(CDCl3): l 1.48 (d, JPH=3.0 Hz, C5Me5), 3.34 (s,
OMe), 5.8–7.9 (m, Ph) ppm. 31P{1H}-NMR (CDCl3):
l 50.4 (d, JRhP=139.6 Hz) ppm. Anal. Calc. for
C29H31O2ClPRh: C, 59.95; H, 5.38. Found: C 59.65; H,
5.15%.
According to analogous procedures orange crystals
of 6e (37 mg, 86%) were prepared from 5 (25 mg, 0.046
mol) and tris(p-tolyl)phosphine (13.9 mg, 0.046 mmol)
in the presence of excess NaPF6. IR (nujol): 1583, 1548,
Complex 3 (26.2 mg, 0.041 mmol) in EtOH (10 ml)
was heated for 3 h in a sealed tube, and the solvent was
removed to dryness and the residue was crystallized
from CH2Cl2/hexane to yield 5 (11 mg, 42%).
839 (PF6) cm−1. UV–vis (CH2Cl2): umax 333 nm. H-
1
NMR (CDCl3): l 1.19 (t, JPH=JP%H=3.3 Hz, C5Me5),
2.40 (bs, p-Me), 3.11 (s, OMe), 5.8–7.6 (c, Ph) ppm.
31P{1H}-NMR (CDCl3): l 22.9 (dd, JRhP=142.1 Hz,
2.7. Heating of 4a in CH2Cl2
A solution of 4a (30 mg, 0.041 mmol) in CH2Cl2 (10
ml) was refluxed for 2 h. The work-up of the mixture
and recrystallization from CH2Cl2 and diethyl ether
gave 3 (24.5 mg, 81%).
J
J
PP=41.0 Hz, MDMPP-P), 51.1 [dd, JRhP=133.7 Hz,
PP=41.0 Hz, (p-tolyl)3P], −143.8 (sep PF6, JPF
=
708.8 Hz) ppm. Anal. Calc. for C50H52O2F6P3Rh: C,
60.37; H, 5.27. Found: C, 60.09; H, 5.00%.

160
X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
Table 1
Crystal data for (p5-C5Me5)RhCl2(MDMPP-P) 2, [(p5-C5Me5)RhCl(MDMPP-P)(p-TosCH2NC)](PF6) 4c, (p5-C5Me5)RhCl(MDMPP-P,O) 5 and
(p5-C5Me5)Rh(MDMPP-P,O)(CO)](PF6)·C6H6 6a·C6H6.
Compound
2
4c
5
6a·C6H6
Formula
MW
C30H34O2PCl2Rh
631.38
C39H43NO4ClSP2F6Rh
936.13
C29H31O2PClRh
580.90
C36H37O3P2F6Rh
896.53
Color
Brown
Orange
Orange
Orange
Crystal dimensions (mm)
Crystal system
Space group
0.50×0.25×0.20
Triclinic
P1 (no. 2)
0.50×0.30×0.20
Orthorhombic
Pna21 (no. 33)
0.2×0.1×0.4
Orthorhombic
Pbca (no. 61)
0.05×0.05×0.20
Monoclinic
C2/c (no. 15)
Lattice parameters
a
b
c
10.639(3)
15.965(3)
8.800(3)
94.43(2)
103.75(3)
88.62(2)
1447.4(7)
2
1.449
648
8.53
16
26.817(4)
17.662(5)
8.673(4)
90.0
90.0
90.0
4108(1)
4
1.513
1912
6.76
8.212(8)
17.808(10)
35.96(1)
90.0
90.0
90.0
5259(4)
8
1.467
2384
8.34
33.29(2)
8.567(5)
29.26(3)
90.0
124.51(3)
90.0
6877(7)
8
1.538
h
i
k
3
˚
V (A )
Z
Dcalc. (g cm−3
F(000)
)
3243
6.56
2
v (cm−1
)
Scan rate (° min−1
)
8
4
No. of reflections (qB50°)
No. of unique data
No. of variables
R, Raw
7013
4424 [I\3.0|(I)]
325
0.039, 0.042
1.25
4109
2061 [I\2.0|(I)]
466
0.052, 0.052
1.24
7245
2673 (I\3.0|(I)]
307
0.047, 0.048
1.22
5143
1531 (I\2.0|(I)]
368
0.072, 0.073
1.30
GOFb
a R=SꢀFoꢁ−ꢁFcꢀ/SꢁFoꢁ and Rw=[Sw(ꢁFoꢁ−ꢁFcꢁ)2/SwꢁFoꢁ ] [w=1/|2(Fo)].
2 1/2
b GOF=[Sw(ꢁFoꢁ−ꢁFcꢁ)2/(Nobs−Nparm)]1/2
.
parameters along with data collections are summarized
in Table 1. Data collection was carried out by a Rigaku
AFC5S refractometer at 25°C. Intensities were mea-
sured by the 2q−ꢀ scan method using Mo–Kh radia-
Complex 6b (42.6 mg, 55%) was obtained from 5
(54.3 mg, 0.093 mol) and xylyl isocyanide (18.4 mg,
0.139 mmol) in the presence of excess NaPF6. IR
1
(nujol): 2183 (NꢀC), 1583, 1545, 839 (PF6) cm−1. H-
˚
tion (u=0.71069 A). Throughout the data collection
NMR (CDCl3): l 1.68 (d, JPH=3.3 Hz, C5Me5), 1.84
(s, o-Me), 3.35 (s, OMe), 6.0–7.6 (c, Ph) ppm.
31P{1H}-NMR (CDCl3): l 47.8 (d, JRhP=116.0 Hz).
Anal. Calc. for C35H40O2NF6P2Rh: C, 55.55; H, 4.91;
N, 1.70. Found: C, 55.65; H, 4.97; N, 1.64%. This
complex 6b was also obtained from the reaction of 6a
with xylyl isocyanide at r.t.
the intensities of the three standard reflections were
measured every 200 reflections as a check of the stabil-
ity of the crystals and any decay was not observed.
Intensities were corrected for Lorentz and polarization
effects. The absorption correction was made. Atomic
scattering factors were taken from Cromer and Waber
[8]. Anomalous dispersion effects were included in Fcalc.
[9]; the values of Df% and Df%% were from Creagh and
McAuley [10]. All calculations were performed using
the teXsan crystallographic software package of Molec-
ular Structure Corporation (1985 and 1992).
2.11. Heating of 4d in EtOH
A solution of 4d (9.5 mg, 0.011 mmol) in EtOH (10
ml) was refluxed for 4 h. The solvent was removed and
the residue was crystallized from CH2Cl2 and diethyl
ether to give 6d (6.8 mg, 75%).
2.13. Determination of the structures
The structures of 2 and 5 were solved by direct
methods (SIR92) and 4c and 6a·C6H6 were solved by
Patterson methods (DIRDIF92 PATTY). The rhodium
atom was located in the initial E map, and subsequent
Fourier syntheses gave the positions of other non-H
atoms. Hydrogen atoms were calculated at the ideal
2.12. Data collection
Complexes 2, 4c and 5 were recrystallized from
CH2Cl2/hexane or CH2Cl2/ether. Complex 6a was re-
crystallized from CH2Cl2/benzene and contained a ben-
zene molecule as a solvated molecule. Cell constants
were determined from 25 reflections on Rigaku four-cir-
cle automated diffractometer AFC5S. The crystal
˚
positions with the C–H distance of 0.95 A, and were
not refined. The positions of the non-H atoms of 2, 4c

X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
161
Fig. 2. Crystal structure of [Cp*RhCl(MDMPP-P)(p-TosCH2-
NC)](PF6) 4c. PF6 is omitted for clarity.
3. Results and discussion
Overall reactions described here are depicted in
Scheme 1. Treatment of 1 with MDMPP at r.t. gave
dark red crystals 2 in a 89% yield, formulated as
Cp*RhCl2[PPh2{2,6-(MeO)2C6H3}]. In the 1H-NMR
spectrum the methyl protons showed a doublet at l
1.15 ppm (JPH=3.5 Hz) which was derived from a
coupling with a P atom because the methyl protons on
the Cp* ring of the starting complex 1 appeared as a
singlet. The methoxy protons appeared at l 3.28 ppm
as a singlet. The 31P{1H}-NMR spectrum showed a
doublet at l 23.5 ppm (JRhP=150.9 Hz). The IR
spectrum showed only one band (1575 cm−1) in the
range from 1500 to 1600 cm−1, suggesting the presence
of the p1-P coordination [4]. It was confirmed by an
X-ray analysis that the structure consists of a piano-
stool in which the rhodium atom is surrounded by a
phosphorus, two chloride atoms and Cp* ring (Fig. 1).
The salient feature of this complex is that the in-
Scheme 1. Reactions of [Cp*RhCl2(MDMPP-P) 2 and its related
complexes. (i) NaPF6. (ii) [N(PhCH2)Et3]Cl. (iii) L=4a: CO, 4b:
XylNC, 4c: p-TosCH2NC, 4d: P(OCH2)3CMe. (iv) L=CO, refluxed
in CH2Cl2. (v) Refluxed in in EtOH. (vi) MDMPP, r.t. in CH2Cl2.
(vii) L=6a: CO, 6b: XylNC, 6d: P(OCH2)3CMe, 6e: P(p-Tolyl)3.
(viii) 4d, refluxed in EtOH.
and 5 were refined with anisotropic thermal parameters
by using full-matrix least-squares methods. The F
atoms for 4c and the C1, C6, and F atoms and a
solvated benzene atoms (C31–C36) for 6c·C6H6 were
refined isotropically and other non-H atoms were
refined anisotropically by using full-matrix least-squares
methods. Final difference Fourier syntheses showed
−3
˚
peaks at heights up to 0.41–0.61 e A
.
Fig. 1. Crystal structure of [Cp*RhCl2(MDMPP-P)] 2.
Fig. 3. Crystal structure of [Cp*RhCl(MDMPP-P,O)] 5.

162
X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
˚
tramolecular Cl1···O1 distance is 3.247 A and the close
interaction between the methoxy group and Cl atom is
expected.
When complex 2 was treated with NaPF6 in an
acetone/CH2Cl2 solution at r.t., an elimination of a Cl
atom occurred readily to form the salt-like O-coordi-
nated complex 3, [Cp*RhCl(MDMPP-P,OMe)][PF6].
The IR spectrum showed two bands at 1585 and 1537
cm−1 in the range from 1500 to 1600 cm−1, indicative
of the presence of the P–O chelation [4]. The PF6 group
was found by a strong band at 835 cm−1. In the
1H-NMR spectrum the methoxy protons appeared at l
3.88 ppm as a broad singlet at ambient temperature,
indicating a rapid exchange between free and coordi-
nated MeO groups. The temperature-dependent NMR
spectra were measured. Two sharp singlets were ob-
served at l 3.34 and 4.43 ppm below ca. −20°C,
assignable to free and coordinated methoxy groups,
respectively. Two singlets became broader with the rise
of temperature and the chemical shift difference became
narrower. The two broad signals coalesced at ca. −
10°C, showing a rapid exchange between two methyl
groups. A coalesced signal became sharper with further
rise of temperature and a sharp singlet appeared at l
3.86 ppm at 50°C. The activation energy for this in-
tramolecular process could be evaluated using the
Eyring equation as ca. 35 kJ mol−1. For RhCl2(P–
O)(P–O)2 [11], RhCl(P–O)(P–O) [12] and RhCl3(P–
O)(P–O) [13] [P–O=R2PCH2CH2OMe (R=C6H11 or
Ph), Ph2PCH2CH2C(O)OEt] the values were 50–75 kJ
mol−1, thus indicating a weaker bonding for 3.
This weak interaction was revealed by the fact that
addition of excess NEt3(CH2Ph)Cl to 3 regenerated 2.
This labile O-coordination also led to the easy replace-
ment with Lewis bases such as CO, XylNC (Xyl=2,6-
Me2C6H3), p-TosCH2NC or P(OCH2)3CMe. When CO
was bubbled into a CH2Cl2 solution of 3 at r.t., com-
pound 4a, formulated as [Cp*RhCl(MDMPP-
P)(CO)][PF6], was formed by an elimination of an
O-coordinated methoxy group and the subsequent co-
ordination of an incoming CO molecule. The similar
complexes 4 (b: L=XylNC; c=p-TosCH2NC; d: L=
P(OCH2)3CMe) were isolated from 3 and the corre-
sponding Lewis bases. However the reaction with
tris(p-tolyl)phosphine recovered the starting material,
due to steric hindrance from the greater cone angle
(145°) of p-tolyl groups than that (101°) of
P(OCH2)3CMe [14].
Fig. 4. Crystal structure of [Cp*Rh(MDMPP-P,O)(CO)](PF6)·C6H6
6a·C6H6. PF6 is omitted for clarity.
1
In the H-NMR spectrum of 4c the methylene pro-
tons showed an AB quartet centered at l 4.68 ppm
arising from chemical inequivalence caused by the pres-
ence of the chiral center. The 31P{1H}-NMR spectrum
showed a doublet at l 22.0 (JRhP=126.9 Hz) ppm for
1
the phosphine ligand. In the H-NMR spectrum of 4d,
the Cp* protons appeared as a double doublet, with
separations of 3.5 and 6.0 Hz, the larger separation
being associated with the entering P(OCH2)3CMe lig-
and. The methoxy and methylene protons appeared at
l 3.34 and 4.15 ppm as a singlet and complex band,
respectively. In the 31P{1H}-NMR spectrum two double
doublets appeared at l 19.0 (JRhP=135.8 Hz, JPP
=
89.0 Hz) and 114.0 (JRhP=223.5 Hz, JPP=89.0 Hz)
ppm; the former is assignable to the MDMPP and the
latter to P(OCH2)3CMe. The X-ray analysis of 4c was
carried out as the representative compound in order
to determine the detailed structures of 4, and the
structure is a typical piano-stool one (Fig. 2). Reac-
tions with small molecules also have been reported in
Cp*Ru(P–O)(PSO)][BPh4]
complex
(P–O=p1-
Ph2PCH2CH2OMe, PSO=p2-Ph2PCH2CH2OMe) [15].
The CO ligand was very labile. When 4a was refluxed
in Ch2Cl2, the CO ligand was eliminated to regenerate
3, whereas heating of 4b in EtOH recovered the starting
material quantitatively, suggesting the stability of a
metal–isocyanide bond.
CO
3
_` 4
−CO/heat
The coordinated CO ligand could be replaced readily
The absence of the P–O chelation was confirmed by
observation of only one band in the range 1500–1600
cm−1 in the IR spectrum of each complex. The charac-
teristic bands of these complexes (4a–c) appeared at
2071 cm−1 for 4a, 2168 cm−1 for 4b and 2214 cm−1
for 4c; the former is assigned to a CO group and the
others to an NC group.
with other Lewis bases. When 4a was treated with
isocyanides or P(OCH2)3CMe in CH2Cl2 at r.t., the
corresponding complex 4b, 4c, or 4d was obtained,
whereas its reverse reaction and an interconversion
between 4b and 4d did not proceed. The difference in
the ligand substitution reactions is due to the fact that

X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
163
Table 2
Selected bond lengths (A) and angles (°) for 2
˚
˚
Bond lengths (A)
Rh-Cl1
O1-C12
O2-C18
Cl1···O1
2.392(1)
1.357(5)
1.405(6)
3.226(3)
Rh-C12
O1-C17
Rh-Cp*(av)
2.411(1)
1.409(6)
2.190
Rh-P
O2-C16
2.366(1)
1.347(6)
Bond angles (°)
Cl1-Rh-C12
89.00(4)
Cl1-Rh-P
93.05(4)
Cl2-Rh-P
90.02(4)
Although no reaction occurred between 3 and tris(p-
tolyl)phosphine, the complex 6e [L=(p-tolyl)3P] could
be obtained as orange crystals from the reaction of 5
with bulky tris(p-tolyl)phosphine. The presence of the
coordinated MeO group in 3 prevented the reaction
with tert-phosphine, which suggests a considerable
amount of steric hindrance encountered by an entering
ligand.
the rhodium atom in the high oxidation state prefers
isocyanide or phosphine ligands with their strong |-
donor ability to the CO ligand.
When 3 was treated with MDMPP in CH2Cl2at r.t.,
the phosphonium salt MDMPP·MeCl and a neutral
reddish–orange
phenoxido
complex
5
p5-
Cp*RhCl(MDMPP-P,O) were formed. Complex 5
could be prepared also by refuxing 2 in EtOH or
directly by refluxing a mixture of 1 and MDMPP in
EtOH. A similar elimination reaction of MeX from a
MDMPP ligand has been reported from the reaction of
a square-planar PtCl2(MDMPP)2 complex with NaI
under reflux in 2-methoxyethanol [16]. The IR spectrum
showed the presence of the characteristic P,O-chelation
at 1585 and 1537 cm−1. The 1H-NMR spectrum
showed a doublet at l 1.48 (JPH=3.0 Hz) and a singlet
at l 3.34 ppm, assignable to methyl protons of the Cp*
and methoxy groups, respectively. The X-ray analysis
confirmed that the configuration around the Rh atom is
not significantly different from that of (p6-
arene)RuCl(MDMPP-P,O) (Fig. 3) [4].
When a mixture of complex 5 in acetone and CH2Cl2
was treated under a CO atmosphere in the presence of
NaPF6 at r.t., replacement of a Cl anion occurred
readily to give reddish crystals 6a [Cp*Rh(MDMPP-
P,O)(CO)](PF6). Analogously, the reaction with XylNC
or P(OCH2)3CMe in the presence of NaPF6 produced
the corresponding orange salt-like complex 6 (b: L=
XylNC; d=P(OCH2)3CMe). Compound 6d was also
prepared by heating of 4d in EtOH, whereas heating of
4b recovered the starting material.
The IR spectrum of 6a showed a characteristic band
at 2089 cm−1 (due to a CꢀO) and that of 6b, at 2183
cm−1 , due to a CꢀN bond, appearing at higher fre-
quency by ca. 15 cm−1 than those of 4a and 4b,
respectively, due to the higher electronegativity of the O
1
atom than that of a Cl atom. The H-NMR spectrum
of 6d showed two singlets at l 0.60 and 3.32 ppm
assignable to the MeC and MeO protons and a broad
signal at l 3.82 ppm due to the CH2O groups. The Cp*
protons at l 1.53 ppm appeared as a double doublet
appearing at 5.5 and 3.0 Hz, respectively; based on
assignment of 4d, the former coupling constant is re-
sponsible for the P atom of P(OCH2)3CMe and the
latter for MDMPP-O ligand, respectively. The 31P{1H}-
NMR spectrum consisted of a double doublet at l 47.4
ppm (JRhP=121.5, JPP=85.0 Hz) due to MDMPP-O
ligand and l 115.4 (JRhP=230.7, JPP=85.0 Hz) ppm
due to P(OCH2)3CMe ligand. An analogous NMR
behavior was also observed for 6e. In the 1H-NMR
spectrum of 6e, the methyl protons of the Cp* ligand
appeared at l 1.19 ppm as a triplet, separated by
JPH=JP%H=3.3 Hz. The protons of p-methyl and
methoxy groups appeared at l 2.40 (bs) and 3.11 (s)
ppm. The 31P{1H}-NMR spectrum consisted of a dou-
Table 3
˚
Selected bond lengths (A) and angles (°) for 4c
˚
Bond lengths (A)
Rh-Cl1
C31-N1
O1-C12
O2-C18
2.383(4)
1.14(1)
1.36(1)
1.46(2)
Rh-P
S1-O3
O1-C17
Rh-Cp*(av)
2.353(3)
1.45(1)
1.43(2)
2.22
Rh-C31
S1-O4
O2-C16
1.95(1)
1.44(1)
1.34(1)
Bond angles (°)
XCl1-Rh-P
Rh-C31-N1
O3-S1-C32
91.9(1)
172.6(10)
107.5(7)
108.3(7)
Cl1-Rh-C31
C31-N1-C32
O4-S1-C32
88.0(4)
178(1)
107.5(7)
P1-Rh-C31
N1-C32-S1
O3-S1-O4
90.1(3)
109.1(8)
121.5(8)
C32-S1-C33

164
X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
Table 4
˚
Selected bond lengths (A) and angles (°) for 5
˚
Bond lengths (A)
Rh-Cl1
O1-Cl1
Rh-Cp*(av)
2.404(3)
1.284(8)
2.177
Rh-P(1)
O2-C15
2.302(2)
1.393(9)
Rh-O1
O2-C17
2.059(5)
1.39(1)
Bond angles (°)
Cl1-Rh-P
Rh-O1-Cl1
86.56(8)
121.6(5)
Cl1-Rh-O1
O1-Cl1-C16
86.6(2)
116.4(7)
P-Rh-O1
P-Cl1-C16
82.3(1)
113.7(6)
ble doublet at l 22.9 (JRhP=142.1, JPP=41.0 Hz) due
to tris(p-tolyl)phosphine and 51.1 (JRhP=133.7, JPP
41.0 Hz) ppm due to the MDMPP-O ligand. The
structure of this type of complexes was determined by
an X-ray analysis of 6a (Fig. 4).
some interaction between a Cl atom and a methyl
group, which is likely a driving force of an elimination
of MeCl. The Rh–C31 (isocyanide) length of 1.939(10)
=
˚
A in 4c is not significantly different from the Rh–C30
˚
(carbon monoxide) one of 1.96(2) A. The CꢀO and
The CO ligand of 6a could be eliminated readily, as
well as that of 4a. When 6a was treated with xylyl
isocyanide or P(OCH2)3CMe in CH2Cl2 at r.t., the
corresponding complex 6b or 6d was isolated in high
yield, respectively, but the reverse reactions did not
occur. An interconversion between 6b and 6d also did
not proceed.
CꢀN bond lengths fall in the range of the usual triple
bond distances. The Rh–C31–N1 and C31–N1–C32
bond angles in 4c are 172.6(10) and 177(1)°, respec-
tively. These values are not unusual. The Rh–C30–O3
angle in 6a·C6H6 is bent and measures 164(1)°.
4. Conclusion
3.1. Molecular structures
Complexes 2, 3 and 5 showed versatile reactivities for
Lewis bases such as CO, isocyanide and phosphines.
Some of the complexes are interconvertible and the
route from 2 to 6 proceeded stepwise. These complexes
can act as starting materials for chemistry of the
rhodium complexes bearing the P–O coordination. The
diversity of chemical reaction is expected for other
small molecules, such as acetylenes and olefins and
studies of these such molecules are currently in
progress.
The molecular structures of 2, 4c, 5, and 6a·C6H6 are
depicted in Figs. 1–4. The selected bond lengths and
angles are shown in Tables 2–5. All complexes have
piano-stool structures. Average bond angles (A–Rh–B)
among three ligands except the Cp* ring are ca. 90° for
2 and 4c, but ca. 86° for 5 and 6a·C6H6. The bond
angles of the complexes bearing the P–O chelation are
narrower than those of non-chelated complexes. Such
difference was also observed in the Rh–P bond lengths;
non-chelated complexes 2 and 4c are slightly longer
than the chelated complexes 5 and 6a·C6H6, minimiz-
ing the steric influence of tert-phosphine. The Rh–O
bond lengths in 5 and 6a·C6H6 are 2.059(5) and 2.08(1)
5. Supplementary material
˚
A, respectively, being not different significantly.
Tables of positional coordinates, anisotropic parame-
ters, bond lengths, and angles, and a listing of observed
and calculated structure factors are available from Y.
Yamamoto on request.
The salient feature in 2 is an intramolecular interac-
˚
tion of 3.226(3) A between Cl1 and O1 atoms, being
˚
close to a sum (3.20 A) of the van der Waals’ radii of
the two atoms. This value suggested the presence of
Table 5
˚
Selected bond lengths (A) and angles (°) for 6a·C6H6
˚
Bond length (A)
Rh-P
O1-C12
O3-C30
2.334(5)
1.35(2)
1.04(2)
Rh-O1
O2-C16
Rh-Cp*(av)
2.08(1)
1.38(2)
2.208
Rh-C30
O2-C17
1.96(2)
1.43(2)
Bond angle (°)
P1-Rh-O1
Rh-C30-O3
82.1(4)
164(1)
P1-Rh-C30
Rh-P1-Cl1
87.8(6)
99.7(6)
O1-Rh-C30
Rh-O1-C12
86.8(6)
118(1)

X.-H. Han, Y. Yamamoto / Journal of Organometallic Chemistry 561 (1998) 157–165
165
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Acknowledgements
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[8] D.T. Cromer, J.T. Waber, International Tables for X-ray Crys-
tallography, vol. IV, Kynoch Press, Birmingham, UK, Table
2.2A, 1974.
The authors would like to thank Professor Sigetoshi
Takahashi and Fumie Takei in Osaka University for
measurement of FAB mass spectroscopy.
[9] J.A. Ibers, W.C. Hamilton, Acta. Crystallogr. 17 (1964) 781.
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